JP2008111585A - Air conditioner - Google Patents

Abstract

An air conditioner capable of accurately determining the amount of refrigerant even when the temperature around the refrigerant circuit changes in a two-stage compression refrigeration cycle.
In an refrigeration cycle in which heating operation can be performed by switching between one-stage compression and two-stage compression, an outdoor expansion valve is connected to a discharge side of a low-stage compressor. When it becomes a refrigerant | coolant condenser, it arrange | positions in the downstream of the outdoor heat exchanger 23, and adjusts the amount of passage liquid refrigerant | coolants. The liquid level detection sensor 39 detects the amount of liquid refrigerant upstream of the outdoor expansion valve 38. The refrigerant in the bypass refrigerant pipe 70 in which the high stage compressor 71 is provided communicates with the suction side of the low stage compressor 21 via the refrigerant recovery circuit 75.
[Selection] Figure 11

Description

  The present invention relates to an air-conditioning apparatus that makes a determination regarding whether or not the amount of refrigerant in a refrigerant circuit is appropriate.

  Conventionally, with respect to the refrigerant amount in the refrigerant circuit of the air conditioner, in order to determine whether or not an appropriate amount of refrigerant according to the scale, the length of the connection pipe of the refrigerant circuit, and the like is filled, Is operating the air conditioner. In the operation of the air conditioner under the predetermined condition, for example, the degree of supercooling of the refrigerant condensed in the condenser while performing the operation of controlling the degree of superheat of the refrigerant evaporated in the evaporator to be a predetermined value. Is detected to determine whether or not an appropriate amount of refrigerant is filled.

  However, in such operation, even if the degree of superheat can be set to a predetermined value, the temperature of the indoor air that performs heat exchange with the refrigerant in the use side heat exchanger or the heat exchange with the refrigerant in the heat source side heat exchanger. Depending on the temperature or the like of outdoor air as a heat source to be performed, the pressure of each part in the refrigerant circuit changes, and the target value of the degree of supercooling when determining the appropriateness of the refrigerant amount changes. For this reason, it is difficult to improve the determination accuracy when determining the suitability of the refrigerant amount.

On the other hand, in the following Patent Document 1, by detecting the degree of supercooling of the refrigerant at the outlet of the heat source side heat exchanger by performing superheat degree control by the use side expansion mechanism and evaporation pressure control by the compressor. The determination accuracy of the amount of refrigerant charged in the refrigerant circuit is improved.
Japanese Patent Application No. 2004-173839

  However, in the determination of the refrigerant amount described in Patent Document 1 described above, as the operating condition for determining the refrigerant amount, it is necessary to perform superheat degree control by the use side expansion mechanism or evaporative pressure control by the compressor. This is complicated. In addition, for example, the error may increase due to the pressure on the condenser side fluctuating due to a change in the outside air temperature condition, and as an operation condition for more appropriately determining the refrigerant amount, a constant operation state is always set. It is difficult to maintain it stably.

  Further, when the refrigerant amount is determined in a so-called two-stage compression refrigeration cycle in which two compressors are connected in series, the operating conditions for determining the refrigerant amount are further weighted, and control that satisfies the respective operating conditions is performed. There is a need to do this, and it is more complicated.

  The present invention has been made in view of the above points, and an object of the present invention is to simplify the conditions necessary for determining an appropriate refrigerant amount in a two-stage compression refrigeration cycle. An object of the present invention is to provide an air conditioner capable of performing

  An air conditioner according to a first aspect of the present invention includes a main refrigerant circuit, a bypass refrigerant circuit, an operation switching mechanism, a bypass switching mechanism, a refrigerant recovery circuit, a shut-off valve, and a refrigerant detector. The main refrigerant circuit is configured by connecting a first compressor, a heat source side heat exchanger, a use side expansion mechanism, and a use side heat exchanger in order by a refrigerant pipe. The bypass refrigerant circuit has one end with respect to one end of the bypassed portion that is a part of a portion connecting the first compressor and the use side heat exchanger of the main refrigerant pipe, and the other end with respect to the other end of the bypassed portion. Are respectively connected and have a second compressor and a discharge check mechanism in the middle. This discharge check mechanism only allows the flow toward the main refrigerant circuit side to the discharge side of the second compressor. The operation switching mechanism is a first operation in which the heat source side heat exchanger functions as a refrigerant condenser and the use side heat exchanger functions as a refrigerant evaporator, and the heat source side heat exchanger functions as a refrigerant evaporator. The second operation for switching the side heat exchanger to function as a refrigerant condenser is switched. The bypass switching mechanism switches between flowing the refrigerant to the bypassed portion side or the bypass refrigerant circuit side in a state where the operation switching mechanism is set to the second operation. The refrigerant recovery circuit includes a part on the downstream side of the bypassed part and a part of the bypass refrigerant circuit in the second operation in a part connecting the first compressor and the use side heat exchanger in the main refrigerant pipe. Tied. This refrigerant recovery circuit has a suction check mechanism that allows only a flow from the bypass refrigerant circuit side toward the main refrigerant circuit side. The shut-off valve is disposed downstream of the heat source side heat exchanger in the flow direction of the refrigerant in the first operation, and can block the passage of the refrigerant. A refrigerant | coolant detection part performs the detection regarding the quantity of the liquid refrigerant | coolant which exists in the upstream of a flow control mechanism in the flow direction of a refrigerant | coolant. Note that the shutoff valve here may be configured to serve as a use-side expansion mechanism in the refrigerant circuit, or may be present alone in the refrigerant circuit. Here, the heat source side heat exchanger functioning as a refrigerant condenser is not limited to a phase change from a gas state refrigerant to a liquid state, but also, for example, when carbon dioxide is used as the refrigerant. Although it does not change, what changes the refrigerant density by heat exchange is also included. In addition, the use-side heat exchanger functioning as the refrigerant evaporator here does not only change the phase of the liquid refrigerant to the gas state, but also, for example, when carbon dioxide is used as the refrigerant. Although it does not change, what changes the refrigerant density by changing heat is also included.

  Here, the first operation and the second operation can be switched by switching the operation switching mechanism. Further, in the second operation, by switching the bypass switching mechanism, the one-stage compression refrigeration cycle in which the refrigerant flows through the bypassed portion and is compressed only by the first compressor, and the refrigerant flows through the bypass refrigerant circuit to the first compressor. On the other hand, a two-stage compression refrigeration cycle for compression including the second compressor connected in series by the bypass refrigerant circuit can be switched and operated.

  Here, since the bypass refrigerant circuit has a discharge check mechanism, when the bypass switching mechanism is in a switching state in which the refrigerant flows through the bypassed portion, the refrigerant does not flow into the interior. A one-stage compression refrigeration cycle can be realized. The refrigerant recovery circuit connects a part downstream of the bypassed part in the second operation and a part of the bypass refrigerant circuit, and only flows from the bypass refrigerant circuit side to the main refrigerant circuit side. Since the suction check mechanism is allowed, when the operation switching mechanism and the bypass switching mechanism are switched to the two-stage compression refrigeration cycle in the second operation, the suction check mechanism is reversed to perform one-stage compression. This can prevent the refrigerant shortcut. Accordingly, the one-stage compression refrigeration cycle in the first operation, the one-stage compression refrigeration cycle in the second operation, and the two-stage compression refrigeration cycle in the second operation can be appropriately switched and operated.

  In the refrigerant circuit capable of switching between the one-stage compression refrigeration cycle in the first operation, the one-stage compression refrigeration cycle in the second operation, and the two-stage compression refrigeration cycle in the second operation, the one-stage compression refrigeration cycle in the first operation When operating the first compressor in the switching state, if the shutoff valve provided on the downstream side of the heat source side heat exchanger is closed and the flow of the refrigerant is shut off, for example, the heat source side that functions as a condenser The liquid refrigerant condensed in the heat exchanger accumulates mainly in the heat source side heat exchanger upstream of the shutoff valve because the circulation of the refrigerant is interrupted. On the other hand, when the first operation is performed and the first compressor is driven, a portion of the main refrigerant circuit that is downstream of the shutoff valve and upstream of the first compressor (for example, a use-side heat exchanger or the like) ) Is depressurized so that there is almost no refrigerant. Furthermore, since the bypass refrigerant circuit is entirely connected to the suction side of the first compressor in the main refrigerant circuit via the refrigerant recovery circuit, the bypass refrigerant circuit is also decompressed and almost no refrigerant exists. It will not be in a state. For this reason, the refrigerant in the main refrigerant circuit and the bypass refrigerant circuit is intensively collected upstream of the shut-off valve as condensed liquid refrigerant, and the refrigerant detection unit uses the concentrated liquid refrigerant as a target refrigerant. Detection of quantity can be performed.

  Thereby, in the two-stage compression refrigeration cycle, it is possible to determine an appropriate amount of refrigerant while simplifying the conditions for determining the amount of refrigerant.

  An air conditioner according to a second aspect is the air conditioner according to the first aspect, further comprising a memory and a control unit. The memory stores in advance data of a required refrigerant amount that is necessary for appropriately performing the first operation and the second operation. The control unit sets the operation switching mechanism to the first operation based on the detection result by the refrigerant detection unit and the required refrigerant amount, sets the bypass switching mechanism to the bypassed part side, and controls the shutoff valve to be closed, The operation of the second compressor is stopped and the first compressor is operated.

  Here, the controller sets the operation switching mechanism to the first operation, sets the bypass switching mechanism to the bypassed portion side, controls the shutoff valve to close, stops the operation of the second compressor, and performs the first compression. While operating the machine, the required refrigerant amount data stored in the memory is compared with information on the refrigerant amount accumulated on the upstream side of the shutoff valve determined by the refrigerant determination unit.

  Thereby, it becomes possible to automatically determine the excess or deficiency of the refrigerant existing in the refrigerant circuit.

  An air conditioner according to a third aspect of the present invention is the air conditioner according to the first or second aspect of the present invention, further comprising a gas-liquid separator, a gas phase branch expansion mechanism, and a liquid layer branch check mechanism. Yes. The gas-liquid separator branches to the gas phase side from a portion connecting the suction side circuit extending from the suction side of the second compressor in the bypass refrigerant circuit and the use side expansion mechanism and the heat source side heat exchanger in the main refrigerant circuit. The air-layer branch circuit is in communication. In the gas-liquid separator, a liquid layer branch circuit branched from a portion connecting the utilization side expansion mechanism and the heat source side heat exchanger in the main refrigerant circuit is communicated with the liquid layer side. The gas phase branch expansion mechanism is provided in the middle of the gas layer branch circuit. The liquid layer branch check mechanism is provided in the middle of the liquid layer branch circuit and allows only the refrigerant flow from the bypass refrigerant circuit side to the main refrigerant circuit side.

  Here, intermediate pressure refrigerant is generated in the refrigerant circuit during the two-stage compression operation, and the gas phase of the intermediate pressure refrigerant and the discharge gas refrigerant of the low-stage compressor are merged and supplied to the high-stage compressor. Can do.

  As a result, the economizer effect can be exhibited, the oil can be prevented from being deteriorated due to an excessive increase in the discharged refrigerant temperature, and the refrigerant can be prevented from being decomposed, thereby improving the reliability and improving the COP (coefficient of performance) by improving the efficiency.

  An air conditioner according to a fourth aspect of the present invention includes a main refrigerant circuit, a bypass refrigerant circuit, an operation switching mechanism, a bypass switching mechanism, a shut-off valve, a refrigerant detector, a memory, a bypass state quantity detector, and a control. Department. The main refrigerant circuit is configured by connecting a first compressor, a heat source side heat exchanger, a use side expansion mechanism, and a use side heat exchanger in order by a refrigerant pipe. The bypass refrigerant circuit has one end with respect to one end of the bypassed portion that is a part of a portion connecting the first compressor and the use side heat exchanger of the main refrigerant pipe, and the other end with respect to the other end of the bypassed portion. Are connected to each other. The bypass refrigerant circuit includes a second compressor and a discharge check mechanism that allows only the flow toward the main refrigerant circuit on the discharge side of the second compressor. The operation switching mechanism is a first operation in which the heat source side heat exchanger functions as a refrigerant condenser and the use side heat exchanger functions as a refrigerant evaporator, and the heat source side heat exchanger functions as a refrigerant evaporator. The second operation for switching the side heat exchanger to function as a refrigerant condenser is switched. The bypass switching mechanism switches between flowing the refrigerant to the bypassed portion side or the bypass refrigerant circuit side in a state where the operation switching mechanism is set to the second operation. The shut-off valve is disposed downstream of the heat source side heat exchanger in the flow direction of the refrigerant in the first operation, and can block the passage of the refrigerant. A refrigerant | coolant detection part performs the detection regarding the quantity of the liquid refrigerant | coolant which exists in the upstream of a flow control mechanism in the flow direction of a refrigerant | coolant. The bypass state quantity detection unit detects data related to the state quantity of the refrigerant in the bypass refrigerant circuit. The control unit operates the second switching mechanism after the second compressor is operated until the value detected by the bypass state quantity detection unit satisfies a predetermined condition in a state where the bypass switching mechanism is set to the bypassed portion side. The bypass switching mechanism is set to the bypassed portion side, and the first compressor is operated while closing the shutoff valve. Note that the shutoff valve here may be configured to serve as a use-side expansion mechanism in the refrigerant circuit, or may be present alone in the refrigerant circuit. Here, the heat source side heat exchanger functioning as a refrigerant condenser is not limited to a phase change from a gas state refrigerant to a liquid state, but also, for example, when carbon dioxide is used as the refrigerant. Although it does not change, what changes the refrigerant density by heat exchange is also included. In addition, the use-side heat exchanger functioning as the refrigerant evaporator here does not only change the phase of the liquid refrigerant to the gas state, but also, for example, when carbon dioxide is used as the refrigerant. Although it does not change, what changes the refrigerant density by changing heat is also included.

  Here, the first operation and the second operation can be switched by switching the operation switching mechanism. Further, in the second operation, by switching the bypass switching mechanism, the one-stage compression refrigeration cycle in which the refrigerant flows through the bypassed portion and is compressed only by the first compressor, and the refrigerant flows through the bypass refrigerant circuit to the first compressor. On the other hand, a two-stage compression refrigeration cycle for compression including the second compressor connected in series by the bypass refrigerant circuit can be switched and operated.

  Here, since the bypass refrigerant circuit has a discharge check mechanism, when the bypass switching mechanism is in a switching state in which the refrigerant flows through the bypassed portion, the refrigerant does not flow into the interior. A one-stage compression refrigeration cycle can be realized. Further, when the second switching operation is performed in the two-stage compression refrigeration cycle when the bypass switching mechanism is switched to flow the refrigerant through the bypass refrigerant circuit, the refrigerant circuit always passes through the second compressor. It is possible to prevent a refrigerant shortcut that would result in one-stage compression. Accordingly, the one-stage compression refrigeration cycle in the first operation, the one-stage compression refrigeration cycle in the second operation, and the two-stage compression refrigeration cycle in the second operation can be appropriately switched and operated.

  In the refrigerant circuit that can be operated by switching between the one-stage compression refrigeration cycle in the first operation, the one-stage compression refrigeration cycle in the second operation, and the two-stage compression refrigeration cycle in the second operation, the control unit has the bypass switching mechanism bypassed. The second compressor is operated until the value detected by the bypass state quantity detection unit satisfies the predetermined condition in the state set in the section side. As a result, one end side of the bypass refrigerant circuit that is the suction side of the second compressor is not in communication with the main refrigerant circuit, and the other end side of the bypass refrigerant circuit that is the discharge side of the second compressor is the main side. Since the refrigerant communicates with the refrigerant circuit, the refrigerant present in the bypass refrigerant circuit is discharged to the main refrigerant circuit, and there is almost no refrigerant in the bypass refrigerant pipe. And since the discharge check mechanism is provided in the other end side of the bypass refrigerant circuit which is the discharge side of the 2nd compressor, the refrigerant once discharged from the bypass refrigerant pipe to the main refrigerant pipe is bypass refrigerant pipe I can't return to the side.

  Furthermore, when the value detected by the bypass state quantity detection unit satisfies a predetermined condition, the control unit operates the first compressor in the switching state of the one-stage compression refrigeration cycle in the first operation. Thereby, when the shutoff valve provided on the downstream side of the heat source side heat exchanger is closed and the flow of the refrigerant is shut off, for example, the liquid refrigerant condensed in the heat source side heat exchanger functioning as a condenser is Since the circulation of the refrigerant is interrupted, the refrigerant mainly accumulates in the heat source side heat exchanger upstream from the shutoff valve. On the other hand, when the first operation is performed and the first compressor is driven, the refrigerant discharged from the bypass refrigerant circuit to the main refrigerant circuit is sucked into the first compressor and condensed in the heat source heat exchanger. A portion of the refrigerant circuit that is downstream of the shutoff valve and upstream of the first compressor (for example, a use-side heat exchanger) is depressurized so that almost no refrigerant is present. For this reason, the refrigerant in the main refrigerant circuit and the bypass refrigerant circuit is intensively collected upstream of the shut-off valve as condensed liquid refrigerant, and the refrigerant detection unit uses the concentrated liquid refrigerant as a target refrigerant. Detection of quantity can be performed.

  Thereby, in the two-stage compression refrigeration cycle, it is possible to determine an appropriate amount of refrigerant while simplifying the conditions for determining the amount of refrigerant.

  The air conditioner according to the fifth aspect of the present invention further includes a memory that stores in advance data of a required refrigerant amount that is necessary for appropriately performing the first operation and the second operation. The control unit operates the second compressor until a value detected by the bypass state amount detection unit satisfies a predetermined condition in a state where the bypass switching mechanism is set to the bypassed portion side, and then the detection result by the refrigerant detection unit Based on the required amount of refrigerant, the operation switching mechanism is set to the first operation, the bypass switching mechanism is set to the bypassed portion side, and the first compressor is operated while closing the shutoff valve.

  Here, after the control unit operates the second compressor until the value detected by the bypass state quantity detection unit satisfies a predetermined condition with the bypass switching mechanism set to the bypassed portion side, the detection by the refrigerant detection unit Based on the result and the required amount of refrigerant, the operation switching mechanism is set to the first operation, the bypass switching mechanism is set to the bypassed portion side, the shut-off valve is controlled to close, and the first compressor is operated, The required refrigerant amount data stored in the memory is compared with information on the refrigerant amount accumulated on the upstream side of the shutoff valve determined by the refrigerant determination unit.

  Thereby, it becomes possible to automatically determine the excess or deficiency of the refrigerant existing in the refrigerant circuit.

  An air conditioner according to a sixth aspect of the present invention is the air conditioner according to the fifth aspect of the present invention, further comprising a gas-liquid separator, a gas phase branch expansion mechanism, and a liquid layer branch check mechanism. The gas-liquid separator branches to the gas phase side from a portion connecting the suction side circuit extending from the suction side of the second compressor in the bypass refrigerant circuit and the use side expansion mechanism and the heat source side heat exchanger in the main refrigerant circuit. The air-layer branch circuit is in communication. In the gas-liquid separator, a liquid layer branch circuit branched from a portion connecting the utilization side expansion mechanism and the heat source side heat exchanger in the main refrigerant circuit is communicated with the liquid layer side. The gas phase branch expansion mechanism is provided in the middle of the gas layer branch circuit. The liquid layer branch check mechanism is provided in the middle of the liquid layer branch circuit and allows only the refrigerant flow from the bypass refrigerant circuit side to the main refrigerant circuit side.

  Here, intermediate pressure refrigerant is generated in the refrigerant circuit during the two-stage compression operation, and the gas phase of the intermediate pressure refrigerant and the discharge gas refrigerant of the low-stage compressor are merged and supplied to the high-stage compressor. Can do.

  As a result, the economizer effect can be exhibited, the oil can be prevented from being deteriorated due to an excessive increase in the discharged refrigerant temperature, and the refrigerant can be prevented from being decomposed, thereby improving the reliability and improving the COP (coefficient of performance) by improving the efficiency.

  An air conditioner according to a seventh aspect of the present invention includes a main refrigerant circuit, a bypass refrigerant circuit, an operation switching mechanism, a bypass switching mechanism, a bypass recovery circuit, a shut-off valve, and a refrigerant detector. The main refrigerant circuit is configured by connecting a first compressor, a heat source side heat exchanger, a use side expansion mechanism, and a use side heat exchanger in order by a refrigerant pipe. The bypass refrigerant circuit has one end with respect to one end of the bypassed portion that is a part of a portion connecting the first compressor and the use side heat exchanger of the main refrigerant pipe, and the other end with respect to the other end of the bypassed portion. Are connected to each other. This bypass refrigerant circuit has a discharge check mechanism that allows only the flow toward the main refrigerant circuit side on the discharge side of the second compressor and the second compressor in the middle. The operation switching mechanism is a first operation in which the heat source side heat exchanger functions as a refrigerant condenser and the use side heat exchanger functions as a refrigerant evaporator, and the heat source side heat exchanger functions as a refrigerant evaporator. The second operation for switching the side heat exchanger to function as a refrigerant condenser is switched. The bypass switching mechanism switches between flowing the refrigerant to the bypassed portion side or the bypass refrigerant circuit side in a state where the operation switching mechanism is set to the second operation. The bypass recovery circuit connects the suction side and the discharge side of the second compressor in the bypass refrigerant pipe, and has a bypass opening / closing mechanism in the middle. The shut-off valve is disposed downstream of the heat source side heat exchanger in the flow direction of the refrigerant in the first operation, and can block the passage of the refrigerant. A refrigerant | coolant detection part performs the detection regarding the quantity of the liquid refrigerant | coolant which exists in the upstream of a flow control mechanism in the flow direction of a refrigerant | coolant. Note that the shutoff valve here may be configured to serve as a use-side expansion mechanism in the refrigerant circuit, or may be present alone in the refrigerant circuit. Here, the heat source side heat exchanger functioning as a refrigerant condenser is not limited to a phase change from a gas state refrigerant to a liquid state, but also, for example, when carbon dioxide is used as the refrigerant. Although it does not change, what changes the refrigerant density by heat exchange is also included. In addition, the use-side heat exchanger functioning as the refrigerant evaporator here does not only change the phase of the liquid refrigerant to the gas state, but also, for example, when carbon dioxide is used as the refrigerant. Although it does not change, what changes the refrigerant density by changing heat is also included.

  Here, the first operation and the second operation can be switched by switching the operation switching mechanism. Further, in the second operation, by switching the bypass switching mechanism, the one-stage compression refrigeration cycle in which the refrigerant flows through the bypassed portion and is compressed only by the first compressor, and the refrigerant flows through the bypass refrigerant circuit to the first compressor. On the other hand, a two-stage compression refrigeration cycle for compression including the second compressor connected in series by the bypass refrigerant circuit can be switched and operated.

  Here, since the bypass refrigerant circuit has a discharge check mechanism, when the bypass switching mechanism is in a switching state in which the refrigerant flows through the bypassed portion, the refrigerant does not flow into the interior. A one-stage compression refrigeration cycle can be realized. Further, since the bypass recovery circuit has a bypass opening / closing mechanism in the middle of connecting the suction side and the discharge side of the second compressor, the operation switching mechanism and the bypass switching mechanism are switched to the two-stage compression refrigeration cycle in the second operation. When the is switched, it is possible to prevent a refrigerant shortcut that causes one-stage compression by closing the bypass opening / closing mechanism. Accordingly, the one-stage compression refrigeration cycle in the first operation, the one-stage compression refrigeration cycle in the second operation, and the two-stage compression refrigeration cycle in the second operation can be appropriately switched and operated.

  In the refrigerant circuit capable of switching between the one-stage compression refrigeration cycle in the first operation, the one-stage compression refrigeration cycle in the second operation, and the two-stage compression refrigeration cycle in the second operation, the one-stage compression refrigeration cycle in the first operation When operating the first compressor in the switching state, if the shutoff valve provided on the downstream side of the heat source side heat exchanger is closed and the flow of the refrigerant is shut off, for example, the heat source side that functions as a condenser The liquid refrigerant condensed in the heat exchanger accumulates mainly in the heat source side heat exchanger upstream of the shutoff valve because the circulation of the refrigerant is interrupted. On the other hand, when the first operation is performed and the first compressor is driven, a portion of the main refrigerant circuit that is downstream of the shutoff valve and upstream of the first compressor (for example, a use-side heat exchanger or the like) ) Is depressurized, and there is almost no refrigerant. Further, with respect to the bypass refrigerant circuit, the bypass refrigerant circuit is entirely sucked by the first compressor in the main refrigerant circuit via the discharge side of the second compressor by opening the bypass opening / closing mechanism. Since the bypass refrigerant circuit is depressurized, the refrigerant is hardly present. For this reason, the refrigerant in the main refrigerant circuit and the bypass refrigerant circuit is intensively collected upstream of the shut-off valve as condensed liquid refrigerant, and the refrigerant detection unit uses the concentrated liquid refrigerant as a target refrigerant. Detection of quantity can be performed.

  Thereby, in the two-stage compression refrigeration cycle, it is possible to determine an appropriate amount of refrigerant while simplifying the conditions for determining the amount of refrigerant.

  An air conditioner according to an eighth aspect is the air conditioner according to the seventh aspect, further comprising a memory and a control unit. The memory stores in advance data of a required refrigerant amount that is necessary for appropriately performing the first operation and the second operation. The control unit sets the operation switching mechanism to the first operation based on the detection result by the refrigerant detection unit and the required refrigerant amount, sets the bypass switching mechanism to the bypassed part side, opens the bypass opening / closing mechanism, Is closed, and the operation of the second compressor is stopped and the first compressor is operated.

  Here, the control unit sets the operation switching mechanism to the first operation, sets the bypass switching mechanism to the bypassed portion side, opens the bypass opening / closing mechanism, and controls the shutoff valve to close, and operates the second compressor. While the operation is stopped and the first compressor is operated, the required refrigerant amount data stored in the memory is compared with information on the refrigerant amount accumulated on the upstream side of the shutoff valve determined by the refrigerant determination unit.

  Thereby, it becomes possible to automatically determine the excess or deficiency of the refrigerant existing in the refrigerant circuit.

  An air conditioner according to a ninth aspect is the air conditioner according to the seventh aspect or the eighth aspect, further comprising a gas-liquid separator, a gas phase branch expansion mechanism, and a liquid layer branch check mechanism. Yes. The gas-liquid separator branches to the gas phase side from a portion connecting the suction side circuit extending from the suction side of the second compressor in the bypass refrigerant circuit and the use side expansion mechanism and the heat source side heat exchanger in the main refrigerant circuit. The air-layer branch circuit is in communication. In the gas-liquid separator, a liquid layer branch circuit branched from a portion connecting the utilization side expansion mechanism and the heat source side heat exchanger in the main refrigerant circuit is communicated with the liquid layer side. The gas phase branch expansion mechanism is provided in the middle of the gas layer branch circuit. The liquid layer branch check mechanism is provided in the middle of the liquid layer branch circuit and allows only the refrigerant flow from the bypass refrigerant circuit side to the main refrigerant circuit side.

  Here, intermediate pressure refrigerant is generated in the refrigerant circuit during the two-stage compression operation, and the gas phase of the intermediate pressure refrigerant and the discharge gas refrigerant of the low-stage compressor are merged and supplied to the high-stage compressor. Can do.

  As a result, the economizer effect can be exhibited, the oil can be prevented from being deteriorated due to an excessive increase in the discharged refrigerant temperature, and the refrigerant can be prevented from being decomposed, thereby improving the reliability and improving the COP (coefficient of performance) by improving the efficiency.

  In the air conditioner according to the first aspect of the present invention, in the two-stage compression refrigeration cycle, it is possible to determine the appropriate refrigerant amount while simplifying the conditions for performing the determination regarding the refrigerant amount.

  In the air conditioner of the second invention, it becomes possible to automatically determine the excess or deficiency of the refrigerant present in the refrigerant circuit.

  In the air conditioner of the third invention, an economizer effect is obtained.

  In the air conditioner according to the fourth aspect of the present invention, in the two-stage compression refrigeration cycle, it is possible to determine an appropriate refrigerant amount while simplifying the conditions for performing the determination relating to the refrigerant amount.

  In the air conditioner of the fifth invention, it becomes possible to automatically determine the excess or deficiency of the refrigerant existing in the refrigerant circuit.

  In the air conditioner of the sixth invention, an economizer effect is obtained.

  In the air conditioner according to the seventh aspect of the present invention, in the two-stage compression refrigeration cycle, it is possible to determine the appropriate refrigerant amount while simplifying the conditions for performing the determination relating to the refrigerant amount.

  In the air conditioner according to the eighth aspect of the present invention, it becomes possible to automatically determine the excess or deficiency of the refrigerant present in the refrigerant circuit.

  In the air conditioner according to the ninth aspect of the invention, an economizer effect is obtained.

  Hereinafter, embodiments of an air-conditioning apparatus according to the present invention will be described based on the drawings.

(1) Configuration of Air Conditioner FIG. 1 is a schematic configuration diagram of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 is an apparatus used for air conditioning in a room such as a building by performing a vapor compression refrigeration cycle operation. The air conditioner 1 mainly includes an outdoor unit 2 as a single heat source unit, an option unit 3, an indoor unit 4 as a utilization unit connected thereto, an outdoor unit 2, an optional unit 3, and an indoor unit 4. A liquid refrigerant communication pipe 6 and a gas refrigerant communication pipe 7 are provided as refrigerant communication pipes for connecting the two. That is, in the vapor compression refrigerant circuit 10 of the air conditioner 1 of the present embodiment, the outdoor unit 2, the option unit 3, the indoor unit 4, the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7 are connected. Is made up of.

<Indoor unit>
The indoor unit 4 is installed by being embedded or suspended in a ceiling of a room such as a building, or by wall hanging on a wall surface of the room. The indoor unit 4 is connected to the outdoor unit 2 via the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7 and constitutes a part of the refrigerant circuit 10.

  Next, the configuration of the indoor unit 4 will be described.

  The indoor unit 4 mainly has an indoor refrigerant circuit 10a that constitutes a part of the refrigerant circuit 10. The indoor refrigerant circuit 10a mainly includes an indoor expansion valve 41 as an expansion mechanism and an indoor heat exchanger 42 as a use side heat exchanger.

  In the present embodiment, the indoor expansion valve 41 is an electric expansion valve connected to the liquid side of the indoor heat exchanger 42 in order to adjust the flow rate of the refrigerant flowing in the indoor refrigerant circuit 10a.

  In the present embodiment, the indoor heat exchanger 42 is a cross-fin type fin-and-tube heat exchanger composed of heat transfer tubes and a large number of fins, and functions as a refrigerant evaporator during cooling operation. It is a heat exchanger that cools indoor air and functions as a refrigerant condenser during heating operation to heat indoor air.

  In the present embodiment, the indoor unit 4 sucks indoor air into the unit, exchanges heat with the refrigerant in the indoor heat exchanger 42, and then supplies the indoor fan 43 as a blower fan to be supplied indoors as supply air. have. The indoor fan 43 is a fan capable of changing the air volume supplied to the indoor heat exchanger 42. In this embodiment, the indoor fan 43 is a centrifugal fan or a multiblade fan driven by a motor 43m formed of a DC fan motor. It is.

  The indoor unit 4 is provided with various sensors. On the liquid side of the indoor heat exchanger 42, a liquid side temperature sensor 44 that detects the temperature of the refrigerant (that is, the refrigerant temperature corresponding to the condensation temperature during heating operation or the evaporation temperature during cooling operation) is provided. A gas side temperature sensor 45 that detects the temperature of the refrigerant is provided on the gas side of the indoor heat exchanger 42. An indoor temperature sensor 46 that detects the temperature of indoor air flowing into the unit (that is, the indoor temperature) is provided on the indoor air inlet side of the indoor unit 4. In this embodiment, the liquid side temperature sensor 44, the gas side temperature sensor 45, and the room temperature sensor 46 are thermistors. The indoor unit 4 also has an indoor control unit 47 that controls the operation of each part constituting the indoor unit 4. And the indoor side control part 47 comprises a part of control part 8 of the air conditioning apparatus 1, has a microcomputer, memory, etc. provided in order to control the indoor unit 4, Control signals and the like are exchanged with a remote controller (not shown) for individually operating the unit 4, and control signals and the like are exchanged with the outdoor unit 2 via a transmission line (not shown). Can be done.

<Outdoor unit>
The outdoor unit 2 is installed outside a building or the like and is connected to the indoor unit 4 via a liquid refrigerant communication pipe 6 and a gas refrigerant communication pipe 7, and constitutes a refrigerant circuit 10 between the indoor units 4. ing.

  Next, the configuration of the outdoor unit 2 will be described. The outdoor unit 2 mainly has an outdoor refrigerant circuit 10 c that constitutes a part of the refrigerant circuit 10. The outdoor refrigerant circuit 10c mainly includes a low-stage compressor 21 as a first compressor, a four-way switching valve 22, an outdoor heat exchanger 23 as a heat source side heat exchanger, and an outdoor as an expansion mechanism. An expansion valve 38, an accumulator 24, a supercooler 25 as a temperature adjusting mechanism, a liquid side closing valve 26, a gas side closing valve 27, a charging pipe 16 for charging refrigerant, and a charging electromagnetic valve 17 And have.

  The low-stage compressor 21 is a compressor whose operating capacity can be varied. In the present embodiment, the low-stage compressor 21 is a positive displacement compressor driven by a motor 21m whose rotation speed is controlled by an inverter.

  The four-way switching valve 22 is a valve for switching the direction of the refrigerant flow. During the one-stage compression cooling operation (first operation), the outdoor heat exchanger 23 is condensed by the refrigerant compressed by the low-stage compressor 21. In order for the indoor heat exchanger 42 to function as an evaporator for the refrigerant condensed in the outdoor heat exchanger 23, the discharge side of the low-stage compressor 21 and the gas side of the outdoor heat exchanger 23 are In addition to being connected, the suction side (specifically, accumulator 24) of the low-stage compressor 21 and the gas refrigerant communication pipe 7 side can be connected (see the solid line of the four-way switching valve 22 in FIG. 1). In the first-stage compression heating operation (second operation) and the two-stage compression heating operation (second operation), the indoor heat exchanger 42 is used as a refrigerant condenser compressed by the low-stage compressor 21 and the outdoor heat. In order for the exchanger 23 to function as an evaporator for the refrigerant condensed in the indoor heat exchanger 42, the discharge side of the low stage compressor 21 and the gas refrigerant communication pipe 7 side are connected and the low stage compressor 21. Can be connected to the gas side of the outdoor heat exchanger 23 (see the broken line of the four-way switching valve 22 in FIG. 1).

  In the present embodiment, as shown in FIG. 2, the outdoor heat exchanger 23 includes a header 11, a branch capillary 12, and a plurality of flats that connect the header 11 and the branch capillary 12 in parallel with each other at an interval. This is a so-called fin-and-tube heat exchanger having a tube 13. The heat exchanger of the refrigerant circuit to which the present invention is applied is not limited to such a fin & tube type, and may be, for example, a shell & tube type or a plate type. (For example, see FIG. 13). The outdoor heat exchanger 23 functions as a condenser for liquefying the gas refrigerant flowing from the header 11 during the cooling operation by exchanging heat with the air supplied by the outdoor fan 28, and from the branch capillary 12 during the heating operation. It is a heat exchanger that functions as an evaporator that vaporizes the flowing liquid refrigerant. The outdoor heat exchanger 23 has a gas side connected to the low-stage compressor 21 and the four-way switching valve 22 side, and a liquid side connected to the outdoor expansion valve 38 and the liquid refrigerant communication pipe 6 side.

  Further, as shown in FIGS. 2 and 3, a liquid level detection sensor 39 for detecting the amount of condensed liquid refrigerant is provided on the side surface of the outdoor heat exchanger 23. The liquid level detection sensor 39 is a sensor for detecting the amount of liquid refrigerant accumulated in the outdoor heat exchanger 23, and is constituted by a tubular detection member. Here, for example, as shown in FIG. 3, in the case of the cooling operation, the high-temperature gas refrigerant flowing from the low-stage compressor 21 is supplied by the outdoor fan 28 in the outdoor heat exchanger 23. By heat exchange with air, the sensible heat changes, and it is cooled by the outside air temperature while maintaining the gas state. The gas refrigerant then changes in latent heat by further heat exchange with the air supplied by the outdoor fan 28, and condenses at the condensation temperature while keeping the temperature constant, and passes through a gas-liquid two-phase state. It becomes a liquid refrigerant. The liquid level detection sensor 39 detects the boundary between the region where the refrigerant exists in the gas state and the region where the refrigerant exists in the liquid state as the liquid level. Here, the liquid level detection sensor 39 is not limited to the above-described tubular detection member. For example, the liquid level detection sensor 39 is a sensor that detects the amount of liquid refrigerant accumulated in the outdoor heat exchanger 23, and is used for outdoor heat exchange. The liquid refrigerant which is comprised by the thermistor arrange | positioned in multiple places so that the height direction of the container 23 may be met, and is a temperature comparable as a condensing temperature as mentioned above and the superheated part of the gas refrigerant higher than a condensing temperature The boundary between this part and the part may be detected as a liquid level.

  In the present embodiment, the outdoor expansion valve 38 is an electric expansion valve connected to the liquid side of the outdoor heat exchanger 23 in order to adjust the pressure and flow rate of the refrigerant flowing in the outdoor refrigerant circuit 10c. It can also be completely closed.

  In the present embodiment, the outdoor unit 2 has an outdoor fan 28 as a blower fan for sucking outdoor air into the unit, exchanging heat with the refrigerant in the outdoor heat exchanger 23, and then discharging the air outside. ing. The outdoor fan 28 is a fan capable of changing the air volume of air supplied to the outdoor heat exchanger 23. In the present embodiment, the outdoor fan 28 is a propeller fan or the like driven by a motor 28m formed of a DC fan motor.

  The accumulator 24 is connected between the four-way switching valve 22 and the low-stage compressor 21, and can store excess refrigerant generated in the refrigerant circuit 10 in accordance with fluctuations in the operating load of the indoor unit 4. It is a possible container.

  In this embodiment, the subcooler 25 is a double-pipe heat exchanger, and is provided to cool the refrigerant sent to the indoor expansion valve 41 after being condensed in the outdoor heat exchanger 23. . In the present embodiment, the subcooler 25 is connected between the outdoor expansion valve 38 and the liquid side closing valve 26.

  In the present embodiment, a supercooling refrigerant circuit 61 is provided as a cooling source of the supercooler 25. In the following description, a portion obtained by removing the supercooled refrigerant circuit 61 from the refrigerant circuit 10 will be referred to as a main refrigerant circuit for convenience.

  The supercooling refrigerant circuit 61 is connected to the main refrigerant circuit so that a part of the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valve 41 is branched from the main refrigerant circuit and returned to the suction side of the low-stage compressor 21. Has been. Specifically, the supercooling refrigerant circuit 61 is connected so that a part of the refrigerant sent from the outdoor expansion valve 38 to the indoor expansion valve 41 is branched from a position between the outdoor heat exchanger 23 and the supercooler 25. And the junction circuit 65 connected to the suction side of the low-stage compressor 21 so as to return from the outlet of the supercooler 25 on the supercooling refrigerant circuit 61 side to the suction side of the low-stage compressor 21. And have. The branch circuit 64 is provided with a supercooling expansion valve 62 for adjusting the flow rate of the refrigerant flowing through the supercooled refrigerant circuit 61. Here, the supercooling expansion valve 62 is an electric expansion valve. Thereby, the refrigerant sent from the outdoor heat exchanger 23 to the indoor expansion valve 41 is cooled by the refrigerant flowing through the supercooling refrigerant circuit 61 after being depressurized by the supercooling expansion valve 62 in the supercooler 25. That is, the capacity control of the supercooler 25 is performed by adjusting the opening degree of the supercooling expansion valve 62.

  The liquid side shutoff valve 26 and the gas side shutoff valve 27 are valves provided at connection ports with external devices and pipes (specifically, the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe 7). The liquid side closing valve 26 is connected to the outdoor heat exchanger 23. The gas side closing valve 27 is connected to the four-way switching valve 22.

  The outdoor unit 2 is provided with various sensors in addition to the liquid level detection sensor 39 described above. Specifically, the outdoor unit 2 includes a suction pressure sensor 29 that detects the suction pressure of the low-stage compressor 21, a discharge pressure sensor 30 that detects the discharge pressure of the low-stage compressor 21, and a low-stage side. An intake temperature sensor 31 that detects the intake temperature of the compressor 21 and a discharge temperature sensor 32 that detects the discharge temperature of the low-stage compressor 21 are provided. The suction temperature sensor 31 is provided at a position between the accumulator 24 and the low-stage compressor 21. The outdoor heat exchanger 23 includes a heat exchange temperature sensor 33 that detects the temperature of the refrigerant flowing in the outdoor heat exchanger 23 (that is, the refrigerant temperature corresponding to the condensation temperature during the cooling operation or the evaporation temperature during the heating operation). Is provided. On the liquid side of the outdoor heat exchanger 23, a liquid side temperature sensor 34 for detecting the temperature Tco of the refrigerant is provided. A liquid pipe temperature sensor 35 that detects the temperature of the refrigerant (that is, the liquid pipe temperature) is provided at the outlet of the subcooler 25 on the main refrigerant circuit side. The merging circuit 65 of the supercooling refrigerant circuit 61 is provided with a supercooling temperature sensor 63 for detecting the temperature of the refrigerant flowing through the outlet of the supercooler 25 on the supercooling refrigerant circuit 61 side. An outdoor temperature sensor 36 for detecting the temperature of the outdoor air flowing into the unit (that is, the outdoor temperature) is provided on the outdoor air inlet side of the outdoor unit 2. In the present embodiment, the suction temperature sensor 31, the discharge temperature sensor 32, the heat exchange temperature sensor 33, the liquid side temperature sensor 34, the liquid pipe temperature sensor 35, the outdoor temperature sensor 36, and the supercooling temperature sensor 63 are composed of thermistors. The outdoor unit 2 also has an outdoor control unit 37 that controls the operation of each unit constituting the outdoor unit 2. And the outdoor side control part 37 comprises a part of control part 8 of the air conditioning apparatus 1, the microcomputer provided in order to control the outdoor unit 2, memory, the inverter circuit which controls the motor 21m, etc. And control signals and the like can be exchanged with the indoor side control unit 47 of the indoor unit 4 via a transmission line (not shown). That is, the control unit 8 that controls the operation of the entire air conditioner 1 is configured by the indoor side control unit 47, the outdoor side control unit 37, and a transmission line (not shown) that connects the control units 37 and 47. Yes.

<Refrigerant communication piping>
Refrigerant communication pipes 6 and 7 are refrigerant pipes constructed on site when the air conditioner 1 is installed at an installation location such as a building, and installation conditions such as the installation location and a combination of an outdoor unit and an indoor unit. Those having various lengths and tube diameters are used. For this reason, for example, when a new air conditioner is installed, the air conditioner 1 is filled with an appropriate amount of refrigerant according to the installation conditions such as the length and pipe diameter of the refrigerant communication pipes 6 and 7. There is a need to.

<Option unit>
The option unit 3 is installed outside a building or the like, and connects the indoor unit 4 and the outdoor unit 2 via a part of the liquid refrigerant communication pipe 6 and a part of the gas refrigerant communication pipe 7. A refrigerant circuit 10 is configured.

  Next, the configuration of the option unit 3 will be described.

  The option unit 3 mainly has a two-stage compression side refrigerant circuit 10 b that constitutes a part of the refrigerant circuit 10. The two-stage compression side refrigerant circuit 10b mainly includes a bypass pipe 72B that is a part of the liquid refrigerant communication pipe 6, a bypass refrigerant circuit 70 that bypasses both ends of the bypass pipe 72B, and a gas refrigerant communication pipe 7. , A liquid outflow pipe 74B branched from the outdoor unit 2 side of the gas refrigerant communication pipe 7, a liquid inflow pipe 78B branched from the indoor unit 4 side of the gas refrigerant communication pipe 7, a gas outflow pipe 71B, A communication circuit 76B, a high-stage compressor 71 as a second compressor, a three-way valve 72, a high-stage close valve 76, an intermediate close valve 73, an optional expansion valve 78, and a gas-liquid separator 74 And a refrigerant recovery circuit 75.

  The gas-liquid separator 74 separates the gas-liquid two-phase refrigerant into a liquid refrigerant and a gas refrigerant. Specifically, the gas-liquid separator 74 is composed of a sealed container formed in a vertically long cylindrical shape. A liquid inflow pipe 78B and a liquid outflow pipe 74B are connected to the gas-liquid separator 74.

  When the connection state is switched, the three-way valve 72 passes through the bypass pipe 72B (a state indicated by a solid line in FIG. 1) and the bypass refrigerant circuit 70 to pass through the high-stage compressor 71. To switch the state in which the two-stage compression refrigeration cycle is performed (the state indicated by the wavy line in FIG. 1). The high stage compressor 71 is provided with a discharge gas pressure sensor 79H that detects the pressure of the discharge gas and a suction gas pressure sensor 79L that detects the pressure of the suction gas, the frequency of which is controlled by the motor 71m. In the bypass refrigerant circuit 70, a second check valve CV <b> 2 that allows only the refrigerant flow from the bypass refrigerant circuit 70 toward the gas refrigerant communication pipe 7 is provided on the discharge side of the high-stage compressor 71.

  The gas outflow pipe 71B for leading the gas refrigerant from the gas-liquid separator 74 is always in communication with the suction side of the high-stage compressor 71 of the bypass refrigerant circuit 70.

  The intermediate communication circuit 76 is provided with a high-stage stop valve 76 that is an electromagnetic valve, and is provided in parallel so as to connect the suction side and the discharge side of the high-stage compressor 71 in the bypass refrigerant circuit 70. It has been.

  An optional expansion valve 78 is provided in the liquid inflow pipe 78B, and connects the indoor unit 4 side of the liquid refrigerant communication pipe 6 and the gas phase portion of the gas-liquid separator 74.

  The liquid outflow pipe 74 </ b> B connects the outdoor unit 2 side of the liquid refrigerant communication pipe 6 and the liquid phase portion of the gas-liquid separator 74, and the refrigerant flows from the liquid layer of the gas-liquid separator 74 toward the liquid refrigerant communication pipe 6. A third check valve CV3 that allows only flow is provided.

  The liquid refrigerant communication pipe 6 is in a state in which the indoor expansion valve 41 and the outdoor heat exchanger 23 are directly connected by opening the intermediate stop valve 73 that is an electromagnetic valve and closing the optional expansion valve 78 of the liquid inflow pipe 78B. Become. Further, the liquid refrigerant communication pipe 6 closes the intermediate stop valve 73 and opens the optional expansion valve 78 of the liquid inflow pipe 78 </ b> B, so that the refrigerant flows from the indoor unit 4 side of the liquid refrigerant pipe 6 to the gas-liquid separator 74. The liquid phase of the gas-liquid separator 74 flows to the outdoor unit 2 side of the liquid refrigerant communication pipe 6 via the liquid outflow pipe 74B.

  The refrigerant recovery circuit 75 connects the suction side of the high-stage compressor 71 of the bypass refrigerant circuit 70 and the outdoor unit 2 side of the bypass pipe 72B of the gas refrigerant communication pipe 7 across the three-way valve 72. ing. The refrigerant recovery circuit 75 is provided with a first check valve CV1 that allows only a refrigerant flow from the bypass refrigerant circuit 70 toward the outdoor unit 2 side of the gas refrigerant communication pipe 7.

  In this optional unit 3, a gas outflow pipe 71B connecting the gas-liquid separator 74 and the suction side of the high-stage compressor 71 of the bypass refrigerant circuit 70, an option-side expansion valve 78, a gas-liquid separator 74, and a liquid inflow pipe 78B. The liquid outflow pipe 74B and the third check valve CV3 reduce the refrigerant in the high-pressure liquid line to an intermediate pressure and supply it to the gas-liquid separator 74 during the two-stage compression operation, and supply the gas refrigerant in the gas-liquid separator 74 The economizer circuit supplied to the high stage compressor 71 together with the discharge gas refrigerant of the low stage compressor 21 is configured. As a result, the economizer effect is exhibited, the oil is not deteriorated and the refrigerant is decomposed due to an excessive increase in the discharged refrigerant temperature, thereby improving the reliability and improving the COP (coefficient of performance) by improving the efficiency.

  The option unit 3 includes an option control unit 77 that controls the operation of each unit constituting the option unit 3. The two-stage compression side control unit 77 constitutes a part of the control unit 8 of the air conditioner 1, and is an inverter circuit that controls a microcomputer, a memory, and a motor 71m provided to control the option unit 3. Etc., and exchange of control signals and the like can be performed between the indoor side control unit 47 of the indoor unit 4 and the outdoor side control unit 37 of the outdoor unit 2 via a transmission line (not shown). It is like that. That is, the overall operation of the air conditioner 1 is controlled by the indoor side control unit 47, the outdoor side control unit 37, the option control unit 77, and a transmission line (not shown) connecting the control units 37, 47, 77. The control part 8 to perform is comprised.

  As shown in FIG. 4, the control unit 8 is connected so that it can receive detection signals of various sensors 29 to 36, 39, 44 to 46, 63, and various types based on these detection signals and the like. It is connected so that apparatus and valve 21,22,28m, 38,41,43m, 62,71,71m, 72,73,76,78 can be controlled. As shown in FIG. 4, a memory 19 is connected to the control unit 8, and data stored in the memory 19 is read when various controls are performed. Here, the data stored in the memory 19 includes, for example, appropriate refrigerant amount data of the refrigerant circuit 10 of the air conditioner 1 for each property in consideration of the pipe length after construction in the building. As will be described later, the control unit 8 reads out these data when performing the refrigerant automatic charging operation or the refrigerant leakage detection operation, and in the refrigerant circuit 10, the one-stage compression cooling operation, the one-stage compression heating operation, and the two-stage compression heating operation. Are filled with an amount of refrigerant necessary to appropriately perform both of the above. In addition to the appropriate refrigerant amount data (appropriate refrigerant amount Z), the memory 19 stores liquid pipe determined refrigerant amount data (liquid pipe determined refrigerant amount Y) and outdoor heat exchange collected refrigerant amount data (outdoor heat exchange collection). Refrigerant amount X) is stored, and the relationship of Z = X + Y is satisfied. Here, the liquid pipe determined refrigerant amount Y reaches the indoor expansion valve 41 from the downstream side of the outdoor heat exchanger 23 through the outdoor expansion valve 38, the subcooler 25, and the liquid refrigerant communication pipe 6 in the operation described later. (And to the front of the optional expansion valve 78 of the liquid suction pipe 78B branched from the liquid refrigerant communication pipe 6 and to the front of the third check valve CV3 of the liquid outlet pipe 74B branched from the liquid refrigerant communication pipe 6), And when the portion from the branch portion downstream of the outdoor expansion valve 38 to the supercooling expansion valve 62 is sealed with a liquid refrigerant at a constant temperature, the amount of refrigerant fixed to this portion (note that The volume of the portion from the outdoor expansion valve 38 to the subcooler 25 is designed to be small, and the influence on the determination error is small). The outdoor heat exchange collected refrigerant amount X is a refrigerant amount obtained by subtracting the liquid pipe fixed refrigerant amount Y from the appropriate refrigerant amount Z. Further, the memory 19 stores a relational expression that can calculate the amount of refrigerant accumulated from the outdoor expansion valve 38 to the outdoor heat exchanger 23 based on the liquid level height data of the outdoor heat exchanger 23.

  The control unit 8 is connected to a warning display unit 9 including an LED or the like for notifying that a refrigerant leak has been detected in the refrigerant leak detection operation described later. Here, FIG. 4 is a control block diagram of the air conditioner 1.

(2) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 1 of this embodiment is demonstrated.

  As the operation mode of the air conditioner 1 of the present embodiment, the normal operation mode in which the outdoor unit 2 and the constituent devices of the indoor unit 4 are controlled according to the operation load of each indoor unit 4, and the constituent devices of the air conditioner 1 When the test operation is performed after the installation of the refrigerant circuit, the refrigerant circuit 10 is charged with an appropriate amount of refrigerant in the appropriate refrigerant amount automatic charging operation mode, and after such a test operation is finished and the normal operation is started, the refrigerant circuit There is a refrigerant leak detection operation mode in which the presence or absence of refrigerant leak from 10 is determined.

  Hereinafter, the operation | movement in each operation mode of the air conditioning apparatus 1 is demonstrated.

<Normal operation mode>
In the normal operation mode, there are three operation modes including a one-stage compression cooling operation, a one-stage compression heating operation, and a two-stage compression heating operation.

(One-stage compression cooling operation)
First, the one-stage compression cooling operation in the normal operation mode will be described with reference to FIG.

  During the one-stage compression cooling operation, the option unit 3 does not substantially function, and the four-way switching valve 22 is in the state indicated by the solid line in FIG. 5, that is, the discharge side of the low-stage compressor 21 is the gas of the outdoor heat exchanger 23. And the suction side of the low-stage compressor 21 is connected to the gas side of the indoor heat exchanger 42 via the gas-side stop valve 27 and the gas refrigerant communication pipe 7. Further, the three-way valve 72 of the option unit 3 is in the state shown by the solid line in FIG. 5, that is, the bypass refrigerant circuit 70 is connected so that the refrigerant does not flow and the bypass pipe 72B flows. Here, the outdoor expansion valve 38 and the supercooling expansion valve 62 are fully opened, and the liquid side closing valve 26 and the gas side closing valve 27 are also opened. Further, the intermediate closing valve 73 is fully opened. Note that the optional expansion valve 78 is closed.

  In the state of the refrigerant circuit 10, when the low-stage compressor 21, the outdoor fan 28, and the indoor fan 43 are started without driving the high-stage compressor 71, the low-pressure gas refrigerant is transferred to the low-stage compressor 21. It is sucked and compressed to become a high-pressure gas refrigerant. Thereafter, the high-pressure gas refrigerant is sent to the outdoor heat exchanger 23 via the four-way switching valve 22, exchanges heat with the outdoor air supplied by the outdoor fan 28, and condenses to form a high-pressure liquid refrigerant. Become. Then, the high-pressure liquid refrigerant passes through the outdoor expansion valve 38 and flows into the supercooler 25, and is further cooled by performing heat exchange with the refrigerant flowing through the supercooling refrigerant circuit 61 to be in a supercooled state. At this time, a part of the high-pressure liquid refrigerant condensed in the outdoor heat exchanger 23 is branched to the supercooling refrigerant circuit 61 and decompressed by the supercooling expansion valve 62, and then is introduced to the suction side of the low-stage compressor 21. Returned. Here, a part of the refrigerant passing through the supercooling expansion valve 62 is evaporated by being reduced to near the suction pressure of the low-stage compressor 21. And the refrigerant | coolant which flows toward the suction | inhalation side of the low stage side compressor 21 from the exit of the supercooling expansion valve 62 of the supercooling refrigerant circuit 61 passes the supercooler 25, and the outdoor heat exchanger by the side of the main refrigerant circuit Heat exchange is performed with the high-pressure liquid refrigerant sent from 23 to the indoor unit 4.

  Then, the high-pressure liquid refrigerant in a supercooled state is sent to the indoor unit 4 via the liquid-side closing valve 26 and the liquid refrigerant communication pipe 6.

  The high-pressure liquid refrigerant sent to the indoor unit 4 is reduced to near the suction pressure of the low-stage compressor 21 by the indoor expansion valve 41 to become a low-pressure gas-liquid two-phase refrigerant and the indoor heat exchanger 42. The heat is exchanged with indoor air in the indoor heat exchanger 42 and evaporated to become a low-pressure gas refrigerant.

  This low-pressure gas refrigerant is sent to the outdoor unit 2 via the gas refrigerant communication pipe 7 and flows into the accumulator 24 via the gas-side closing valve 27 and the four-way switching valve 22. Then, the low-pressure gas refrigerant that has flowed into the accumulator 24 is again sucked into the low-stage compressor 21.

  Here, the refrigerant distribution state of the refrigerant circuit 10 during the one-stage compression cooling operation flows as shown by a thick line along with an arrow in the refrigerant circuit in FIG. It is distributed in each phase state and gas state.

  Specifically, upstream of the outdoor expansion valve 38 and downstream of the outdoor heat exchanger 23, the upstream side of the indoor expansion valve 41 including the subcooler 25 of the main refrigerant circuit and the liquid refrigerant communication pipe 6. (And before the optional expansion valve 78 of the liquid suction pipe 78B branched from the liquid refrigerant communication pipe 6 and before the third check valve CV3 of the liquid outflow pipe 74B branched from the liquid refrigerant communication pipe 6) And the upstream side of the supercooling expansion valve 62 is filled with the refrigerant in the liquid state.

  Then, from the indoor expansion valve 41 to the downstream side of the indoor heat exchanger 42, from the supercooling expansion valve 62 to the downstream side in the supercooling refrigerant circuit 61 of the supercooler 25, and upstream of the outdoor heat exchanger 23, Filled with a liquid two-phase refrigerant.

  Furthermore, the other part of the refrigerant circuit 10, that is, the gas refrigerant communication pipe 7 (including the bypassed pipe 72 </ b> B) of the main refrigerant circuit, and the branched part from the gas refrigerant communication pipe 7, starting from the upstream side of the indoor heat exchanger 42. To the front of the second check valve CV2 on the discharge side of the high-stage compressor 71 of the bypass refrigerant circuit 70, from the branch portion of the liquid refrigerant communication pipe 6 to the front of the first check valve CV1 of the refrigerant recovery circuit 75, From the upstream side of the subcooler 25 of the supercooling refrigerant circuit 61 to the downstream, the downstream side of the outdoor heat exchanger 23 including the accumulator 24 and the low-stage compressor 21 includes the downstream side of the supercooling refrigerant circuit 61. Filled with refrigerant.

  In the normal one-stage compression cooling operation, the refrigerant is distributed in the refrigerant circuit 10 in such a distribution, but in the one-stage compression cooling operation in the proper refrigerant amount automatic charging operation and the refrigerant leakage detection operation described later, the liquid refrigerant is used. The liquid refrigerant is collected in the communication pipe 6 and the outdoor heat exchanger 23.

(Heating operation)
(One-stage compression heating operation)
Next, the one-stage compression heating operation in the normal operation mode will be described.

  During the one-stage compression heating operation, the option unit 3 does not substantially function, and the four-way switching valve 22 is in the state shown by the solid line in FIG. 6, that is, the discharge side of the low-stage compressor 21 is the gas-side closing valve 27 and the gas. The refrigerant is connected to the gas side of the indoor heat exchanger 42 via the refrigerant communication pipe 7, and the suction side of the low-stage compressor 21 is connected to the gas side of the outdoor heat exchanger 23. Further, the three-way valve 72 of the option unit 3 is in a state shown by a solid line in FIG. 6, that is, a state in which no refrigerant flows through the bypass refrigerant circuit 70 and is connected so that the refrigerant flows through the bypass pipe 72B. The degree of opening of the outdoor expansion valve 38 is adjusted so as to reduce the refrigerant flowing into the outdoor heat exchanger 23 to a pressure at which the refrigerant can evaporate in the outdoor heat exchanger 23 (that is, evaporation pressure). . Moreover, the liquid side closing valve 26 and the gas side closing valve 27 are opened. The opening of the indoor expansion valve 41 is adjusted so that the degree of supercooling of the refrigerant at the outlet of the indoor heat exchanger 42 is constant. In this embodiment, the degree of supercooling of the refrigerant at the outlet of the indoor heat exchanger 42 is calculated by converting the discharge pressure of the low-stage compressor 21 detected by the discharge pressure sensor 30 into a saturation temperature value corresponding to the condensation temperature, It is detected by subtracting the refrigerant temperature value detected by the liquid side temperature sensor 44 from the saturation temperature value of the refrigerant. Further, the supercooling expansion valve 62 and the optional expansion valve 78 are closed. Further, the intermediate closing valve 73 is fully opened. Although the refrigerant recovery circuit 75 connects the gas refrigerant communication pipe 7 and the bypass refrigerant circuit 70, the refrigerant flow from the gas refrigerant communication pipe 7 side is not allowed by the first check valve CV1. The refrigerant does not flow into the refrigerant circuit 70.

  When the low-stage compressor 21, the outdoor fan 28, and the indoor fan 43 are activated in the state of the refrigerant circuit 10, the low-pressure gas refrigerant is converted into the low-stage compressor 21 as indicated by the arrows and thick lines in FIG. 6. And is compressed into high-pressure gas refrigerant, and is sent to the indoor unit 4 via the four-way switching valve 22, the gas-side closing valve 27, and the gas refrigerant communication pipe 7.

  The high-pressure gas refrigerant sent to the indoor unit 4 undergoes heat exchange with the indoor air in the indoor heat exchanger 42 to condense into a high-pressure liquid refrigerant, and then passes through the indoor expansion valve 41. Further, the pressure is reduced according to the opening degree of the indoor expansion valve 41.

  The refrigerant that has passed through the indoor expansion valve 41 is sent to the outdoor unit 2 via the liquid refrigerant communication pipe 6 and further reduced in pressure via the liquid side closing valve 26, the subcooler 25, and the outdoor expansion valve 38. Later, it flows into the outdoor heat exchanger 23. The low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 23 exchanges heat with the outdoor air supplied by the outdoor fan 28 to evaporate into a low-pressure gas refrigerant. And flows into the accumulator 24. Then, the low-pressure gas refrigerant that has flowed into the accumulator 24 is again sucked into the low-stage compressor 21.

(Two-stage compression heating operation)
Furthermore, the two-stage compression heating operation in the normal operation mode will be described.

  During the two-stage compression heating operation, while the option unit 3 is functioning, the four-way switching valve 22 is in the state shown by the solid line in FIG. 7, that is, the discharge side of the low-stage compressor 21 is the gas-side closing valve 27 and the gas refrigerant. It is connected to the gas side of the indoor heat exchanger 42 via the connecting pipe 7, and the suction side of the low-stage compressor 21 is connected to the gas side of the outdoor heat exchanger 23. Further, the three-way valve 72 of the option unit 3 is in a state indicated by a solid line in FIG. 7, that is, a state in which the refrigerant flows through the bypass refrigerant circuit 70 and is switched and connected so that the refrigerant does not flow into the bypass pipe 72B. The The degree of opening of the outdoor expansion valve 38 is adjusted so as to reduce the refrigerant flowing into the outdoor heat exchanger 23 to a pressure at which the refrigerant can evaporate in the outdoor heat exchanger 23 (that is, evaporation pressure). . Moreover, the liquid side closing valve 26 and the gas side closing valve 27 are opened. The opening of the indoor expansion valve 41 is adjusted so that the degree of supercooling of the refrigerant at the outlet of the indoor heat exchanger 42 is constant. In this embodiment, the degree of supercooling of the refrigerant at the outlet of the indoor heat exchanger 42 is calculated by converting the discharge pressure of the low-stage compressor 21 detected by the discharge pressure sensor 30 into a saturation temperature value corresponding to the condensation temperature, It is detected by subtracting the refrigerant temperature value detected by the liquid side temperature sensor 44 from the saturation temperature value of the refrigerant. The supercooling expansion valve 62 is closed. Moreover, the high stage side closing valve 76 is also closed. Further, the optional expansion valve 78 is opened while the intermediate closing valve 73 is closed.

  When the low-stage compressor 21, the high-stage compressor 71, the outdoor fan 28, and the indoor fan 43 are activated in the state of the refrigerant circuit 10, the low-pressure gas refrigerant is as shown by arrows and thick lines in FIG. Then, the refrigerant is sucked into the low-stage compressor 21 and compressed to become an intermediate-pressure gas refrigerant, and is passed through the four-way switching valve 22, the gas-side shut-off valve 27, the gas refrigerant communication pipe 7, and the bypass refrigerant circuit 70. The refrigerant is combined with the gas refrigerant from the gas outflow pipe 71 </ b> B of the separator 74, compressed into high-pressure gas in the high-stage compressor 71, and sent to the indoor unit 4.

  The high-pressure gas refrigerant sent to the indoor unit 4 undergoes heat exchange with the indoor air in the indoor heat exchanger 42 to condense into a high-pressure liquid refrigerant, and then passes through the indoor expansion valve 41. Further, the pressure is reduced according to the opening degree of the indoor expansion valve 41.

  The refrigerant that has passed through the indoor expansion valve 41 passes through the liquid refrigerant communication pipe 6, and the intermediate stop valve 73 is closed and the optional expansion valve 78 is opened. It flows into the gas phase part of the separator 74. And it is sent to the outdoor unit 2 from the liquid phase part of the gas-liquid separator 78 via the liquid outflow pipe 74B.

  The refrigerant sent to the outdoor unit 2 is further depressurized via the liquid side closing valve 26, the subcooler 25 and the outdoor expansion valve 38, and then flows into the outdoor heat exchanger 23. The low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 23 exchanges heat with the outdoor air supplied by the outdoor fan 28 to evaporate into a low-pressure gas refrigerant. And flows into the accumulator 24. Then, the low-pressure gas refrigerant that has flowed into the accumulator 24 is again sucked into the low-stage compressor 21.

  The operation control in the normal operation mode as described above is performed by the control unit 8 (more specifically, functioning as normal operation control means for performing normal operation including one-stage compression cooling operation, one-stage compression heating operation, and two-stage compression heating operation. , A transmission line connecting between the indoor side control unit 47, the outdoor side control unit 37, and the control units 37, 47, 57).

<Appropriate refrigerant amount automatic charging operation mode>
Here, the proper refrigerant amount automatic charging operation mode will be described.

  The proper refrigerant amount automatic charging operation mode is an operation mode that is performed during a trial operation after installation of the components of the air conditioner 1, and the liquid refrigerant communication pipe 6 and the gas refrigerant communication pipe in a state where the optional refrigerant circuit 70 does not function. The refrigerant circuit 10 is automatically filled with an appropriate amount of refrigerant corresponding to the volume of 7.

  First, the liquid side shut-off valve 26 and the gas side shut-off valve 27 of the outdoor unit 2 are opened to fill the refrigerant circuit 10 with the refrigerant that has been filled in the outdoor unit 2 in advance.

  Next, an operator who performs an appropriate refrigerant amount automatic charging operation connects the refrigerant cylinder 15 for additional charging to the charging electromagnetic valve 17 of the refrigerant circuit 10. As a result, the charging electromagnetic valve 17 is in a state of being connected to the suction side of the low-stage compressor 21 and the high-stage compressor 71 via the charging pipe 16, and is capable of charging the refrigerant circuit 10 with the refrigerant. . The charging electromagnetic valve 17 is connected to the outdoor side control unit 37 so that the opening amount of the valve is controlled so that the charging amount from the refrigerant cylinder 15 can be controlled. At the stage of connection to 17, the filling electromagnetic valve 17 is in a closed state.

  In addition, the filling point in a refrigerant circuit is not restricted to this, For example, you may make it install the service port which can be filled from the gas side closing valve 27 vicinity at the time of filling. Further, the filling electromagnetic valve 17 here is either a case where it is configured to be capable of opening and closing only as a solenoid valve or a case where the flow rate adjustment is also configured as an electric valve. Good.

  When the operator issues a command to start the appropriate refrigerant amount automatic charging operation directly or through a remote controller (not shown) or the like to the control unit 8, the control unit 8 causes steps S11 to S11 shown in FIG. The process of step S19 is performed. Here, FIG. 8 is a flowchart of the proper refrigerant amount automatic charging operation.

  Hereinafter, each step will be described in order.

  In step S <b> 11, the control unit 8 fully opens the filling electromagnetic valve 17 when the connection of the refrigerant cylinder 15 to the filling electromagnetic valve 17 is completed.

  In step S12, the control unit 8 performs the same operation as the one-stage compression cooling operation in the normal operation mode described above. That is, in the state where the four-way switching valve 22 of the outdoor unit 2 is shown by the solid line in FIG. 1, the three-way valve 72 of the option unit 3 is switched to the bypass pipe 72B so that the refrigerant flows, The indoor expansion valve 41, the intermediate closing valve 73, and the outdoor expansion valve 38 are opened, the optional expansion valve 78 is closed, the low-stage compressor 21, the outdoor fan 28, and the indoor fan 43 are activated, and the indoor unit 4 Forcibly perform all-stage compression cooling operation. Accordingly, the refrigerant sealed in the refrigerant cylinder 15 is positively charged into the refrigerant circuit 10 via the filling electromagnetic valve 17 and the filling pipe 16.

  Moreover, in step S12, the control part 8 performs liquid temperature constant control simultaneously with performing the one-stage compression cooling operation mentioned above. In this liquid temperature constant control, condensing pressure control and liquid pipe temperature control are performed.

  In the condensation pressure control, the air volume of the outdoor air supplied to the outdoor heat exchanger 23 by the outdoor fan 28 is controlled so that the condensation pressure of the refrigerant in the outdoor heat exchanger 23 becomes constant. Since the condensing pressure of the refrigerant in the condenser changes more greatly than the influence of the outdoor temperature, the air volume of the indoor air supplied from the outdoor fan 28 to the outdoor heat exchanger 23 is controlled by the motor 28m. For this reason, the condensation pressure of the refrigerant in the outdoor heat exchanger 23 becomes constant, and the state of the refrigerant flowing in the condenser is stabilized. Thereby, the flow path including the outdoor expansion valve 38 from the outdoor heat exchanger 23 to the indoor expansion valve 41, the portion on the main refrigerant circuit side of the subcooler 25, and the liquid refrigerant communication pipe 6 (bypass pipe 72B) and the outdoor heat. A high-pressure liquid refrigerant flows through the flow path from the exchanger 23 to the supercooling expansion valve 62 of the supercooling refrigerant circuit 61. Therefore, the pressure of the refrigerant in the portion from the outdoor heat exchanger 23 to the indoor expansion valve 41 and the supercooled expansion valve 62 is also stabilized and sealed with the liquid refrigerant to be in a stable state. In the control of the condensation pressure, the discharge pressure of the compressor 21 detected by the discharge pressure sensor 30 or the temperature of the refrigerant flowing in the outdoor heat exchanger 23 detected by the heat exchange temperature sensor 33 is used.

  In the liquid pipe temperature control, the capacity of the supercooler 25 is controlled so that the temperature of the refrigerant sent from the supercooler 25 to the indoor expansion valve 41 is constant. Thereby, the refrigerant density in the refrigerant pipe including the liquid refrigerant communication pipe 6 extending from the supercooler 25 to the indoor expansion valve 41 can be stabilized. Here, the capacity control of the supercooler 25 is control for increasing or decreasing the flow rate of the refrigerant flowing through the supercooling refrigerant circuit 61 so that the temperature of the refrigerant detected by the liquid pipe temperature sensor 35 is constant. Thereby, the amount of exchange heat between the refrigerant flowing on the main refrigerant circuit side of the subcooler 25 and the refrigerant flowing on the bypass refrigerant circuit side is adjusted. In addition, increase / decrease in the flow volume of the refrigerant | coolant which flows through this supercooling refrigerant circuit 61 is performed because the control part 8 adjusts the opening degree of the supercooling expansion valve 62. FIG.

  In step S13, the controller 8 determines whether or not the liquid temperature has been stabilized by performing the liquid temperature constant control in step S12. If it is determined that the liquid temperature is constant, the process proceeds to step S14. On the other hand, if it is determined that the liquid temperature is not yet constant, the process returns to step S12 to continue the liquid temperature constant control.

  When the liquid temperature is controlled to be constant by the constant liquid temperature control, the outdoor portion of the refrigerant circuit 10, that is, the outdoor expansion valve 38, the subcooler 25, and the liquid refrigerant communication pipe 6 from the downstream side of the outdoor heat exchanger 23. To the indoor expansion valve 41 (and to the front of the optional expansion valve 78 of the liquid suction pipe 78B branched from the liquid refrigerant communication pipe 6 and the liquid outflow pipe 74B branched from the liquid refrigerant communication pipe 6). 3 (before 3 check valve CV3) and from the branch portion downstream of the outdoor expansion valve 38 to the supercooling expansion valve 62 are stably sealed by the liquid refrigerant at a constant temperature. Accordingly, the one-stage compression cooling operation in the refrigerant circuit 10 is stably performed while the refrigerant amount of the liquid pipe determined refrigerant amount Y stored in the memory 19 is always maintained in the portion sealed with the liquid refrigerant. It will be in a state that has been broken.

  In step S14, since it is confirmed that the liquid temperature is constant, the control unit 8 closes the indoor expansion valve 41, closes the supercooling expansion valve 62, and closes the outdoor expansion valve 38. . Thereby, while the refrigerant amount of the liquid pipe determined refrigerant amount Y is maintained, the circulation of the refrigerant can be stopped, and the accurate refrigerant of the liquid pipe determined refrigerant amount Y can remain in the portion. Note that the operation of the low-stage compressor 21 and the outdoor fan 28 is continued even after each expansion valve is closed. Thereby, the part from the indoor expansion valve 41 to the suction side of the low-stage compressor 21 is depressurized, and the indoor heat exchanger 42, the gas refrigerant communication pipe 7, and the accumulator 24 are in a state in which almost no refrigerant exists. It will become. Further, as shown in FIG. 10, the refrigerant discharged from the discharge side of the low-stage compressor 21 performs heat exchange with outdoor air sent from the outdoor fan 28 in the outdoor heat exchanger 23, and is in a gaseous state. The liquid refrigerant accumulates from the upstream side of the outdoor expansion valve 38 to the outdoor heat exchanger 23.

  Here, as the outdoor fan 28 continues to rotate, the outdoor heat exchanger 23 continuously performs heat exchange with the outdoor air sent from the outdoor fan 28. For this reason, first, the high-temperature gas refrigerant flowing from the low-stage compressor 21 is cooled to the condensation temperature while maintaining the gas state in the outdoor heat exchanger 23 by heat exchange with the outdoor air. (Sensible heat change). The gas refrigerant then condenses at the condensation temperature and becomes a liquid refrigerant (latent heat change). Further, since the circulation of the refrigerant is interrupted, actually, the refrigerant in a liquid state accumulates from the upstream side of the outdoor expansion valve 38 to the lower side of the outdoor heat exchanger 23 as shown in FIG.

  In step S <b> 15, the control unit 8 detects the liquid level of the refrigerant accumulated in the outdoor heat exchanger 23 by the liquid level detection sensor 39. Here, the liquid level detection sensor 39 detects the liquid level of the liquid refrigerant. As a result, the control unit 8 substitutes the height h of the liquid level obtained by the liquid level detection sensor 39 (see FIG. 10) into the relational expression stored in the memory 19, so that the outdoor expansion valve 38 The amount of refrigerant accumulated over the heat exchanger 23 is calculated.

In step S16, the controller 8 determines that the amount of refrigerant calculated in step S15 is
It is determined whether or not the outdoor heat exchange collected refrigerant amount X stored in the memory 19 has been reached. Here, when the outdoor heat exchange collected refrigerant amount X has not been reached, the process returns to step S14 and the refrigerant circuit 10 is continuously charged with the refrigerant. On the other hand, when it is determined that the outdoor heat exchange collected refrigerant amount X has been reached, the process proceeds to step S17.

  In step S <b> 17, the control unit 8 determines that the refrigerant circuit 10 has been filled with an appropriate amount of refrigerant, and closes the charging electromagnetic valve 17 in order to stop charging the refrigerant from the refrigerant cylinder 15 into the refrigerant circuit 10. . As a result, the refrigerant circuit 10 is filled with the appropriate refrigerant amount Z that is the sum of the liquid pipe determined refrigerant amount Y and the outdoor heat exchange collected refrigerant amount X. Then, the charging electromagnetic valve 17 is closed, the refrigerant cylinder 15 is removed, and the proper refrigerant amount automatic charging operation is ended.

<Refrigerant leak detection operation mode>
Next, the refrigerant leak detection operation mode will be described.

  In the present embodiment, the refrigerant leakage detection operation mode is, for example, periodically (such as a time zone in which air conditioning is not required during holidays or midnight), and the refrigerant does not leak to the outside from the refrigerant circuit 10 due to an unexpected cause. This is an operation performed when detecting whether or not.

  The refrigerant leakage detection operation mode is shown in FIG. 9 by the control unit 8 when the operator issues a command to start the refrigerant leakage detection operation to the control unit 8 directly or through a remote controller (not shown). Steps S21 to S28 are performed. Here, FIG. 9 is a flowchart of the refrigerant leak detection operation.

  Hereinafter, each step will be described in order.

  In step S21, the control unit 8 performs the same operation as the one-stage compression cooling operation in the normal operation mode described above. That is, the control unit 8 switches the three-way valve 72 of the option unit 3 to the bypass pipe 72B so that the refrigerant flows in the state where the four-way switching valve 22 of the outdoor unit 2 is indicated by the solid line in FIG. The indoor expansion valve 41, the intermediate closing valve 73, and the outdoor expansion valve 38 of the indoor unit 4 are opened, the optional expansion valve 78 and the high stage side closing valve 76 are closed, and the low stage side compressor 21 and the outdoor fan 28 are closed. And the indoor fan 43 is started and the one-stage compression cooling operation is forcibly performed for all the indoor units 4.

  Accordingly, as shown in FIG. 11, from the downstream side of the outdoor heat exchanger 23 in the refrigerant circuit 10 to the indoor expansion valve 41 via the outdoor expansion valve 38, the subcooler 25, and the liquid refrigerant communication pipe 6. (And to the front of the optional expansion valve 78 of the liquid suction pipe 78B branched from the liquid refrigerant communication pipe 6 and to the front of the third check valve CV3 of the liquid outlet pipe 74B branched from the liquid refrigerant communication pipe 6), And the part from the branch part downstream of the outdoor expansion valve 38 to the supercooling expansion valve 62 is filled with the liquid refrigerant.

  On the other hand, as shown by a thick line in FIG. 11, the refrigerant scattered in the option unit 3 is sucked into the low-stage compressor 21 and discharged to the gas refrigerant communication pipe 7. Specifically, when the low-stage compressor 21 is operated, the pressure of the gas refrigerant communication pipe 7 decreases, and the discharge side of the high-stage compressor 71 of the bypass refrigerant circuit 70 (the high level of the intermediate communication circuit 76B). The refrigerant scattered in the discharge side pipe (including the discharge side pipe from the stage side stop valve 76) passes through the second check valve CV2 in the passage permission direction and is discharged toward the gas refrigerant communication pipe 7. The Further, the operation of the low-stage compressor 21 causes the pressure of the gas refrigerant communication pipe 7 to decrease, and the liquid inflow pipe 78B option from the third check valve of the liquid outflow pipe 74B to the gas-liquid separator 74 is optional. From the expansion valve 78 to the gas-liquid separator 74, in the gas-liquid separator 74, the gas outflow pipe 71B, the suction side of the high-stage compressor 71 of the bypass refrigerant circuit 70 (from the high-stage side closing valve 76 of the intermediate communication circuit 76B) The refrigerant dispersed in the refrigerant recovery circuit 75 is discharged toward the gas refrigerant communication pipe 7 by passing in the direction of allowing passage of the first check valve CV1. . Note that the liquid refrigerant present in the liquid inflow pipe 78B, the liquid outflow pipe 74B, and the gas-liquid separator 74 becomes a gaseous state by being depressurized, and is discharged through the gas outflow pipe 71B.

  Moreover, in step S21, the control part 8 performs liquid temperature constant control simultaneously with performing the one-stage compression cooling operation mentioned above. In this liquid temperature constant control, condensing pressure control and liquid pipe temperature control are performed. The condensing pressure control and the liquid pipe temperature control here are the same as in the above-described proper refrigerant amount automatic charging operation, and the description thereof will be omitted.

  In step S22, the controller 8 determines whether or not the liquid temperature has been stabilized by performing the liquid temperature constant control in step S21. If it is determined that the liquid temperature is constant, the process proceeds to step S23. On the other hand, if it is determined that the liquid temperature is not yet constant, the process returns to step S21 and the liquid temperature constant control is continued.

  When the liquid temperature is controlled to be constant by the constant liquid temperature control, the outdoor portion of the refrigerant circuit 10, that is, the outdoor expansion valve 38, the subcooler 25, and the liquid refrigerant communication pipe 6 from the downstream side of the outdoor heat exchanger 23. To the indoor expansion valve 41 (and to the front of the optional expansion valve 78 of the liquid suction pipe 78B branched from the liquid refrigerant communication pipe 6 and the liquid outlet pipe 74B branched from the liquid refrigerant communication pipe 6). 3 (before 3 check valve CV3) and from the branch portion downstream of the outdoor expansion valve 38 to the supercooling expansion valve 62 are stably sealed by the liquid refrigerant at a constant temperature. Accordingly, the one-stage compression cooling operation in the refrigerant circuit 10 is stably performed while the refrigerant amount of the liquid pipe determined refrigerant amount Y stored in the memory 19 is always maintained in the portion sealed with the liquid refrigerant. It will be in a state that has been broken.

  In step S23, since it is confirmed that the liquid temperature is constant, the control unit 8 closes the indoor expansion valve 41, closes the supercooling expansion valve 62, and closes the outdoor expansion valve 38. . As a result, the refrigerant amount of the liquid pipe determined refrigerant amount Y is determined, the refrigerant circulation is stopped, and the accurate liquid pipe determined refrigerant amount Y of refrigerant can remain in the portion. Note that the operation of the low-stage compressor 21 and the outdoor fan 28 is continued even after each expansion valve is closed. Thereby, the part from the indoor expansion valve 41 to the suction side of the low-stage compressor 21 is depressurized, and almost no refrigerant is contained in the indoor heat exchanger 42, the gas refrigerant communication pipe 7, the accumulator 24, and the option unit 3. It will be in a state that does not exist. Further, as shown in FIG. 10, the refrigerant discharged from the discharge side of the low-stage compressor 21 performs heat exchange with outdoor air sent from the outdoor fan 28 in the outdoor heat exchanger 23, and is in a gaseous state. The liquid refrigerant accumulates from the upstream side of the outdoor expansion valve 38 to the outdoor heat exchanger 23.

  Here, as the outdoor fan 28 continues to rotate, the outdoor heat exchanger 23 continuously performs heat exchange with the outdoor air sent from the outdoor fan 28. For this reason, first, the high-temperature gas refrigerant flowing from the low-stage compressor 21 is cooled to the condensation temperature while maintaining the gas state in the outdoor heat exchanger 23 by heat exchange with the outdoor air. (Sensible heat change). The gas refrigerant then condenses at the condensation temperature and becomes a liquid refrigerant (latent heat change). Further, since the circulation of the refrigerant is interrupted, actually, the refrigerant in a liquid state is accumulated from the upstream side of the outdoor expansion valve 38 to the lower side of the outdoor heat exchanger 23 as shown in FIGS. To go.

  In step S24, the control unit 8 detects the liquid level of the refrigerant accumulated in the outdoor heat exchanger 23 by the liquid level detection sensor 39 and detects the liquid level detected by the liquid level detection sensor 39, as shown in FIG. It is determined whether the height h is maintained unchanged for a predetermined time. If the detected liquid level height h has not changed for a predetermined time, it is determined that all the refrigerant in the refrigerant circuit 10 has been collected, and the process proceeds to step S25. When the detected liquid level height h changes, the operation is continued for a while.

  In step S25, the control unit 8 acquires the detected liquid level height h that does not change.

  In Step S <b> 26, the control unit 8 substitutes the detected liquid level height h that does not change into the relational expression stored in the memory 19, thereby determining liquid refrigerant that has accumulated from the outdoor expansion valve 38 to the outdoor heat exchanger 23. The quantity X ′ is calculated. Then, the control unit 8 determines whether or not the refrigerant leaks in the refrigerant circuit 10 depending on whether or not the value obtained by adding the liquid pipe determined refrigerant amount Y to the calculated determination liquid refrigerant amount X ′ becomes the appropriate refrigerant amount Z. Judgment is made. When the value obtained by adding the liquid pipe fixed refrigerant amount Y to the calculated determination liquid refrigerant amount X ′ is smaller than the appropriate refrigerant amount, the control unit 8 determines that leakage has occurred and proceeds to step S27. Transition. If it is equal to the appropriate refrigerant amount Z, the controller 8 determines that no leakage has occurred, and proceeds to step S28.

  In step S27, in order to notify the occurrence of refrigerant leakage, the control unit 8 notifies the warning display unit 9 that leakage has occurred.

  In step S28, after acquiring the data of the liquid level height h without changing the liquid level height h for a predetermined time, the operation of the low-stage compressor 21 is quickly stopped. Thereby, the refrigerant leakage detection operation is terminated.

  Further, the determination of the refrigerant leakage detection here is not limited to the method of calculating the determination liquid refrigerant amount X ′ as described above. For example, the reference liquid level height H corresponding to the optimal refrigerant amount is calculated in advance. By storing in the memory 19, it is not necessary to calculate the determination liquid refrigerant amount X ′ as described above, and the detected liquid level height h is directly compared with the reference liquid level height H as an index. Thus, refrigerant leakage detection may be performed.

(3) Features of the air conditioner The air conditioner 1 of the present embodiment has the following features.

(A)
In the refrigerant circuit 10 of the air conditioning apparatus 1 of the present embodiment, the one-stage compression cooling operation, the one-stage compression heating operation, and the two-stage compression heating operation are switched by switching the four-way switching valve 22 and the three-way valve 72. Can do.

  And since the refrigerant circuit 10 which can perform such various operation | movements is provided with the refrigerant | coolant collection circuit 75 which has 1st non-return valve CV1, appropriate refrigerant | coolant amount automatic filling operation and refrigerant | coolant leak detection are carried out. Conditions for performing the operation can be simplified, and the refrigerant amount can be accurately determined by collecting the existing refrigerant in a liquid state in one place.

(B)
In the refrigerant circuit 10 of the air conditioning apparatus 1 of the present embodiment, since the second check valve CV2 is provided in the bypass refrigerant circuit 70, the switching state is such that the three-way valve 72 allows the refrigerant to flow through the bypass pipe 72B. In this case, the refrigerant does not flow into the bypass refrigerant circuit 70, and the one-stage compression refrigeration cycle can be realized accurately.

  In addition, since the refrigerant recovery circuit 75 has the first check valve CV1, when the two-stage compression heating operation is performed, a refrigerant that flows into the bypass refrigerant circuit 70 and becomes one-stage compression. Shortcuts can be prevented.

(C)
In the air conditioner 1 of the present embodiment, an intermediate-pressure refrigerant is generated in the refrigerant circuit during the two-stage compression heating operation, and the gas phase of the intermediate-pressure refrigerant and the discharge gas refrigerant of the low-stage compressor are merged. Supply to the stage side compressor 71. Thereby, the economizer effect can be exhibited, the oil can be prevented from being deteriorated due to the excessive increase in the discharged refrigerant temperature, and the refrigerant can be prevented from being decomposed, thereby improving the reliability and improving the COP (coefficient of performance) by improving the efficiency.

(4) Other Embodiments Although the embodiments of the present invention have been described with reference to the drawings, the specific configuration is not limited to these embodiments and can be changed without departing from the scope of the invention. It is.

(A)
In the air conditioner 1 of the present embodiment, in the refrigerant leakage detection operation, the refrigerant dispersed in the option unit 3 is recovered and the gas refrigerant communication pipe 7 is decompressed by operating the low-stage compressor 21. The case where the process is performed through the refrigerant recovery circuit 75 or the like has been described as an example.

  However, the present invention is not limited to this. For example, as shown in FIG. 14, a circuit configuration in which the above-described refrigerant recovery circuit 75 is not provided may be employed. In the case of this circuit configuration, as indicated by a thick line in the refrigerant circuit 10 of FIG. 14, the control unit 8 is configured to perform three-way compression before or simultaneously with the one-stage compression cooling operation in step S21 in the flow of the refrigerant leakage detection operation. The valve 72 is switched to the bypassed pipe 72b side, the high stage side closing valve 76 is closed, the optional expansion valve 78 is closed, and the high stage side compressor 71 is operated. Thereby, the effect similar to the said embodiment can be acquired.

  That is, as shown by a thick line in the refrigerant circuit of FIG. 14, when the high stage side stop valve 76 is in the closed state, the high stage side compressor 71 operates so that the refrigerant scattered in the option unit 3 is bypassed. The refrigerant passes through the second check valve CV2 from the discharge side of the high-stage compressor 71 of the refrigerant circuit 70 in the passage permission direction, and is discharged to the gas refrigerant communication pipe 7. Specifically, the suction side of the high-stage compressor 71 is depressurized so that the gas from the third check valve CV3 of the liquid outflow pipe 74B to the gas-liquid separator 74 and from the optional expansion valve 78 of the liquid inflow pipe 78B. Up to the liquid separator 74, in the gas-liquid separator 74, in the gas outflow pipe 71B, the suction side of the high-stage side opening / closing valve 76 of the intermediate communication circuit 76B, and the suction side of the high-stage side compressor 71 of the bypass refrigerant circuit 70 The scattered refrigerant is sucked by the high stage compressor 71 and is discharged toward the gas refrigerant communication pipe 7 by passing in the direction of allowing passage of the second check valve CV2. The liquid refrigerant existing in the liquid inflow pipe 78B, the liquid outflow pipe 74B, and the gas-liquid separator 74 becomes a gaseous state as the pressure is reduced, and is discharged through the gas outflow pipe 71B.

  Thus, after the refrigerant | coolant scattered in the option unit 3 is discharged | emitted toward the gas refrigerant communication piping 7, the operation | movement similar to the 1st compression cooling operation mentioned above is performed. Thereby, the refrigerant in the refrigerant circuit 10 is stored in a liquid state in the outdoor heat exchanger 23, and refrigerant leakage detection can be performed.

  As in the above embodiment, since the second check valve CV2 is provided in the bypass refrigerant circuit 70, when the three-way valve 72 is in a switching state in which the refrigerant flows through the bypass pipe 72B. The refrigerant does not flow into the bypass refrigerant circuit 70 and can accurately realize the one-stage compression refrigeration cycle.

  Furthermore, here, when the two-stage compression heating operation is performed in a switching state in which the three-way valve 72 flows the refrigerant to the bypass refrigerant circuit 70, the refrigerant circuit always passes through the high-stage compressor 71. Therefore, it is possible to prevent a refrigerant shortcut that would result in one-stage compression.

(B)
In the air conditioner 1 of the present embodiment, in the refrigerant leakage detection operation, the refrigerant dispersed in the option unit 3 is recovered and the gas refrigerant communication pipe 7 is decompressed by operating the low-stage compressor 21. The case where the process is performed through the refrigerant recovery circuit 75 or the like has been described as an example.

  However, the present invention is not limited to this. For example, as shown in FIG. 15, a circuit configuration in which the above-described refrigerant recovery circuit 75 is not provided may be employed. Even in such a circuit configuration, as indicated by a thick line in the refrigerant circuit 10 of FIG. 15, the control unit 8 connects the three-way valve 72 to the bypass pipe 72b side in step S21 in the flow of the refrigerant leakage detection operation. The optional expansion valve 78 is closed, the high-stage side stop valve 76 of the intermediate communication circuit 76B is opened, and the low-stage compressor 21 is operated. Thereby, the effect similar to the said embodiment can be acquired.

  That is, as shown by a thick line in the refrigerant circuit of FIG. 15, when the high-stage side stop valve 76 is in the open state, the low-stage side compressor 21 is operated, whereby the pressure of the gas refrigerant communication pipe 7 is lowered. The refrigerant scattered in the option unit 3 passes through the second check valve CV2 in the passage permission direction from the discharge side of the high-stage compressor 71 of the bypass refrigerant circuit 70 to the gas refrigerant communication pipe 7. It will be discharged. Specifically, from the third check valve CV3 of the liquid outflow pipe 74B to the gas-liquid separator 74, from the optional expansion valve 78 of the liquid inflow pipe 78B to the gas-liquid separator 74, the gas outflow in the gas-liquid separator 74 The refrigerant scattered on the suction side of the high-stage compressor 71 of the pipe 71B and the bypass refrigerant circuit 70 passes through the intermediate communication circuit 76B (the high-stage side stop valve 76 is controlled to be open), and the second reverse By passing toward the passage permission direction of the stop valve CV2, it is discharged toward the gas refrigerant communication pipe 7. The liquid refrigerant existing in the liquid inflow pipe 78B, the liquid outflow pipe 74B, and the gas-liquid separator 74 becomes a gaseous state as the pressure is reduced, and is discharged through the gas outflow pipe 71B.

  Thus, after the refrigerant | coolant scattered in the option unit 3 is discharged | emitted toward the gas refrigerant communication piping 7, the operation | movement similar to the 1st compression cooling operation mentioned above is performed. Thereby, the refrigerant in the refrigerant circuit 10 is stored in a liquid state in the outdoor heat exchanger 23, and refrigerant leakage detection can be performed.

  As in the above embodiment, since the second check valve CV2 is provided in the bypass refrigerant circuit 70, when the three-way valve 72 is in a switching state in which the refrigerant flows through the bypass pipe 72B. The refrigerant does not flow into the bypass refrigerant circuit 70 and can accurately realize the one-stage compression refrigeration cycle.

  Further, since the intermediate communication circuit 76B includes the high stage side opening / closing valve 76 in the middle of connecting the suction side and the discharge side of the high stage side compressor 71, when performing the two-stage compression heating operation, the intermediate communication circuit 76B By closing the high-stage on-off valve 76 of the circuit 76B, it is possible to prevent a refrigerant shortcut that causes one-stage compression.

(C)
In the air conditioner of the above embodiment, the air conditioner 1 in which one indoor unit 4 is connected to one outdoor unit 2 has been described as an example.

  However, the present invention is not limited to this. For example, a refrigerant circuit having a configuration in which a plurality of indoor units are connected in parallel to a single outdoor unit 2 may be used.

  Furthermore, the refrigerant circuit of the structure by which the several outdoor unit was connected in parallel with respect to the indoor unit may be sufficient.

  Even in these cases, the appropriate refrigerant amount automatic charging operation and the refrigerant leakage detection operation can be performed by the same control as the above-described flow.

(D)
Moreover, in this invention, the structure by which the bypass valve was provided in the hot gas bypass circuit which connects the discharge side and suction | inhalation side of the low stage side compressor 21, for example may be sufficient. Here, the bypass valve is connected to the outdoor control unit 37 and is intermittently controlled to open and close, and through this hot gas bypass circuit, the refrigerant can be guided to the suction side of the low-stage compressor 21, and the low-stage compressor It is possible to secure at least a certain amount of refrigerant discharged from 21.

  Thus, in each of the embodiments described above, when the proper refrigerant amount automatic charging operation is performed or when the refrigerant leakage detection operation is performed, the pressure on the suction side of the low-stage compressor 21 rapidly decreases, and the discharge side The problem of overheating can be avoided.

  If the present invention is used, conditions necessary for determining an appropriate amount of refrigerant in the two-stage compression refrigeration cycle can be simplified, and particularly, the refrigerant circuit of the two-stage compression refrigeration cycle is charged. The present invention can be applied to an air conditioner that determines the amount of refrigerant that has been used.

It is a schematic block diagram of the air conditioning apparatus concerning one Embodiment of this invention. It is the schematic of an outdoor heat exchanger. It is a conceptual diagram which shows the refrigerant | coolant which accumulates in an outdoor heat exchanger. It is a control block diagram of an air conditioning apparatus. It is a state explanatory view of the refrigerant circuit in the case of performing one-stage compression cooling operation. It is a state explanatory view of the refrigerant circuit in the case of performing one-stage compression heating operation. It is state explanatory drawing of the refrigerant circuit in the case of performing a two-stage compression heating operation. It is a flowchart of a proper refrigerant | coolant amount filling operation. It is a flowchart of a refrigerant | coolant leak detection driving | operation. It is a figure which shows a mode that a liquid refrigerant is stored in an outdoor heat exchanger. It is a figure which shows the driving | running state which collect | recovers the refrigerant | coolant scattered in the option unit. It is a schematic diagram which shows the state of the refrigerant | coolant at the time of collect | recovering refrigerant | coolants to an outdoor heat exchanger. The figure which shows another example of an outdoor heat exchanger. It is a figure which shows the refrigerant | coolant collection | recovery driving | operation of the air conditioning apparatus which concerns on other embodiment (A). It is a figure which shows the refrigerant | coolant collection | recovery driving | operation of the air conditioning apparatus which concerns on other embodiment (B).

Explanation of symbols

1 Air conditioner 2 Outdoor unit (heat source unit)
4 Indoor units (units used)
6 Liquid refrigerant communication piping (refrigerant communication piping)
7 Gas refrigerant communication pipe (refrigerant communication pipe)
8 Control Unit 10 Refrigerant Circuit 19 Memory 21 Low Stage Compressor (First Compressor)
22 Four-way switching valve (operation switching mechanism)
23 Outdoor heat exchanger (heat source side heat exchanger)
38 Outdoor expansion valve (shutoff valve)
39 Liquid level detection sensor (refrigerant detection part)
41 Indoor expansion valve (expansion mechanism)
42 Indoor heat exchanger (use side heat exchanger)
43 Indoor fans (fans)
70 Bypass refrigerant circuit 71 High stage compressor (second compressor)
71B Gas outflow pipe (suction side circuit)
72 Three-way valve (Bypass switching mechanism)
72B Bypassed piping (bypassed part)
74 Gas-liquid separator 74B Liquid outflow pipe (liquid layer branch circuit)
75 Refrigerant recovery circuit 78 Optional expansion valve (gas phase branch expansion mechanism)
78B Liquid inflow pipe (Air-layer branch circuit)
CV1 first check valve (suction check mechanism)
CV2 Second check valve (Discharge check mechanism)
CV3 Third check valve (Liquid layer branch check mechanism)

Claims (9)

A main refrigerant configured by sequentially connecting a first compressor (21), a heat source side heat exchanger (23), a use side expansion mechanism (41), and a use side heat exchanger (42) by a refrigerant pipe. A circuit (10);
One end of the main refrigerant pipe (10) with respect to one end of the bypassed portion (72B) that is a part of a portion connecting the first compressor (21) and the use side heat exchanger (42), The other end is connected to the other end of the bypassed portion (72B), and the main refrigerant circuit (10) side is connected to the discharge side of the second compressor (71) and the second compressor (71) in the middle. A bypass refrigerant circuit (70) having a discharge check mechanism (CV2) that allows only a flow toward
A first operation in which the heat source side heat exchanger (23) functions as a refrigerant condenser and the use side heat exchanger (42) functions as a refrigerant evaporator, and the heat source side heat exchanger (23) is a refrigerant. An operation switching mechanism (22) for switching between a second operation for functioning as an evaporator and a function for causing the use side heat exchanger (42) to function as a refrigerant condenser;
In the state where the operation switching mechanism (22) is set to the second operation, the bypass for switching whether the refrigerant flows to the bypassed part (72B) side or the bypass refrigerant circuit (70) side. A switching mechanism (72);
Of the portion connecting the first compressor (21) and the use side heat exchanger (42) in the main refrigerant pipe (10), part of the downstream side of the bypassed portion (72B) in the second operation. And a part of the bypass refrigerant circuit (70), and a suction check mechanism (CV1) that allows only a flow from the bypass refrigerant circuit (70) side to the main refrigerant circuit (10) side. A refrigerant recovery circuit (75);
A shut-off valve (38) disposed downstream of the heat source side heat exchanger (23) in the flow direction of the refrigerant in the first operation and capable of blocking the passage of the refrigerant;
A refrigerant detector (39) for detecting the amount of liquid refrigerant existing upstream of the flow rate adjusting mechanism (38) in the flow direction of the refrigerant;
An air conditioner (1) comprising: A memory (19) that stores in advance data of a required refrigerant amount that is necessary for properly performing the first operation and the second operation;
Based on the detection result by the refrigerant detection unit (39) and the required refrigerant amount, the operation switching mechanism (22) is set to the first operation, and the bypass switching mechanism (72) is set to the bypassed part (72B). And a control unit (8) for stopping the operation of the second compressor (71) and operating the first compressor (21) while closing the shut-off valve (38).
Further equipped with,
The air conditioner (1) according to claim 1. On the gas phase side, a suction side circuit (71B) extending from the suction side of the second compressor (71) in the bypass refrigerant circuit (70), and the use side expansion mechanism (41) in the main refrigerant circuit (10) A gas layer branch circuit (78B) branched from a portion connecting the heat source side heat exchanger (23) communicates with the use side expansion mechanism (41) in the main refrigerant circuit (10) on the liquid layer side. A gas-liquid separator (74) to which a liquid layer branch circuit (74B) branched from a portion connecting the heat source side heat exchanger (23) is communicated;
A gas phase branch expansion mechanism (78) provided in the middle of the gas layer branch circuit (78B);
A liquid layer branch check mechanism (CV3) that is provided in the middle of the liquid layer branch circuit (74B) and allows only a refrigerant flow from the bypass refrigerant circuit (70) side to the main refrigerant circuit (10) side;
Further equipped with,
The air conditioner (1) according to claim 1 or 2. A main refrigerant configured by sequentially connecting a first compressor (21), a heat source side heat exchanger (23), a use side expansion mechanism (41), and a use side heat exchanger (42) by a refrigerant pipe. A circuit (10);
One end of the main refrigerant pipe (10) with respect to one end of the bypassed part (72B) which is a part of a portion connecting the first compressor (21) and the use side heat exchanger (23), The other end is connected to the other end of the bypassed portion (72B), and the main refrigerant circuit (10) side is connected to the discharge side of the second compressor (71) and the second compressor (71) in the middle. A bypass refrigerant circuit (70) having a discharge check mechanism (CV2) that allows only a flow toward
A first operation in which the heat source side heat exchanger (23) functions as a refrigerant condenser and the use side heat exchanger (42) functions as a refrigerant evaporator, and the heat source side heat exchanger (23) is a refrigerant. An operation switching mechanism (22) for switching between a second operation for functioning as an evaporator and a function for causing the use side heat exchanger (42) to function as a refrigerant condenser;
In the state where the operation switching mechanism (22) is set to the second operation, the bypass for switching whether the refrigerant flows to the bypassed part (72B) side or the bypass refrigerant circuit (70) side. A switching mechanism (72);
A shut-off valve (38) disposed downstream of the heat source side heat exchanger (23) in the flow direction of the refrigerant in the first operation and capable of blocking the passage of the refrigerant;
A refrigerant detector (39) for detecting the amount of liquid refrigerant existing upstream of the flow rate adjusting mechanism (38) in the flow direction of the refrigerant;
A bypass state quantity detector (79H, 79L) for detecting data relating to the state quantity of the refrigerant in the bypass refrigerant circuit (70);
In the state where the bypass switching mechanism (72) is set on the bypassed part (72B) side, the second compressor (until the value detected by the bypass state quantity detecting part (79H, 79L) satisfies a predetermined condition ( 71) is operated, the operation switching mechanism (22) is set to the first operation, the bypass switching mechanism (72) is set to the bypassed part (72B) side, and the shut-off valve (38) is set. A control unit (8) for operating the first compressor (21) while performing closing control;
An air conditioner (1) comprising: A memory (19) that stores in advance data of a required amount of refrigerant necessary for properly performing the first operation and the second operation;
The control unit (8) is configured so that a value detected by the bypass state quantity detection unit (79H, 79L) satisfies a predetermined condition in a state where the bypass switching mechanism (72) is set to the bypassed part (72B) side. After operating the second compressor (71) until it is satisfied, the operation switching mechanism (22) is set to the first operation based on the detection result by the refrigerant detector (39) and the required refrigerant amount. The bypass switching mechanism (72) is set on the bypassed part (72B) side, and the first compressor (21) is operated while the shutoff valve (38) is controlled to be closed.
The air conditioner (1) according to claim 4. On the gas phase side, a suction side circuit (71B) extending from the suction side of the second compressor (71) in the bypass refrigerant circuit (70), and the use side expansion mechanism (41) in the main refrigerant circuit (10) A gas layer branch circuit (78B) branched from a portion connecting the heat source side heat exchanger (23) communicates with the use side expansion mechanism (41) in the main refrigerant circuit (10) on the liquid layer side. A gas-liquid separator (74) to which a liquid layer branch circuit (74B) branched from a portion connecting the heat source side heat exchanger (23) is communicated;
A gas phase branch expansion mechanism (78) provided in the middle of the gas layer branch circuit (78B);
A liquid layer branch check mechanism (CV3) that is provided in the middle of the liquid layer branch circuit (74B) and allows only a refrigerant flow from the bypass refrigerant circuit (70) side to the main refrigerant circuit (10) side;
Further equipped with,
The air conditioner (1) according to claim 4 or 5. A main refrigerant configured by sequentially connecting a first compressor (21), a heat source side heat exchanger (23), a use side expansion mechanism (41), and a use side heat exchanger (42) by a refrigerant pipe. A circuit (10);
One end of the main refrigerant pipe (10) with respect to one end of the bypassed portion (72B) that is a part of a portion connecting the first compressor (21) and the use side heat exchanger (42), The other end is connected to the other end of the bypassed portion (72B), and the main refrigerant circuit (10) side is connected to the discharge side of the second compressor (71) and the second compressor (71) in the middle. A bypass refrigerant circuit (70) having a discharge check mechanism (CV2) that allows only a flow toward
A first operation in which the heat source side heat exchanger (23) functions as a refrigerant condenser and the use side heat exchanger (42) functions as a refrigerant evaporator, and the heat source side heat exchanger (23) is a refrigerant. An operation switching mechanism (22) for switching between a second operation for functioning as an evaporator and a function for causing the use side heat exchanger (42) to function as a refrigerant condenser;
In the state where the operation switching mechanism (22) is set to the second operation, the bypass for switching whether the refrigerant flows to the bypassed part (72B) side or the bypass refrigerant circuit (70) side. A switching mechanism (72);
A bypass recovery circuit (76B) connecting the suction side and the discharge side of the second compressor (71) in the bypass refrigerant pipe (70) and having a bypass opening / closing mechanism (76) in the middle;
A shut-off valve (38) disposed downstream of the heat source side heat exchanger (23) in the flow direction of the refrigerant in the first operation and capable of blocking the passage of the refrigerant;
A refrigerant detector (39) for detecting the amount of liquid refrigerant existing upstream of the flow rate adjusting mechanism (38) in the flow direction of the refrigerant;
An air conditioner (1) comprising: A memory (19) that stores in advance data of a required refrigerant amount that is necessary for properly performing the first operation and the second operation;
Based on the detection result by the refrigerant detection unit (39) and the required refrigerant amount, the operation switching mechanism (22) is set to the first operation, and the bypass switching mechanism (72) is set to the bypassed part (72B). ) Side, the bypass opening / closing mechanism (76) is opened, the shutoff valve (38) is controlled to be closed, and the operation of the second compressor (71) is stopped to stop the first compressor (21). A control unit (8) for operating
Further equipped with,
The air conditioning apparatus (1) according to claim 7. On the gas phase side, a suction side circuit (71B) extending from the suction side of the second compressor (71) in the bypass refrigerant circuit (70), and the use side expansion mechanism (41) in the main refrigerant circuit (10) A gas layer branch circuit (78B) branched from a portion connecting the heat source side heat exchanger (23) communicates with the use side expansion mechanism (41) in the main refrigerant circuit (10) on the liquid layer side. A gas-liquid separator (74) to which a liquid layer branch circuit (74B) branched from a portion connecting the heat source side heat exchanger (23) is communicated;
A gas phase branch expansion mechanism (78) provided in the middle of the gas layer branch circuit (78B);
A liquid layer branch check mechanism (CV3) that is provided in the middle of the liquid layer branch circuit (74B) and allows only a refrigerant flow from the bypass refrigerant circuit (70) side to the main refrigerant circuit (10) side;
Further equipped with,
The air conditioner (1) according to claim 7 or 8.

Images