JP2014119220A - Refrigeration device - Google Patents

Abstract

In a refrigeration apparatus using an R32 refrigerant, there is provided a refrigeration apparatus capable of injection for suppressing a discharge temperature even when an excessive operating capacity is output in intermediate injection.
An air conditioner 10 using an R32 refrigerant includes a compressor 20, an outdoor heat exchanger 30 and an indoor heat exchanger 50 as a condenser and an evaporator, an outdoor expansion valve 41, an indoor expansion valve 42, and a first injection. A flow path 65, a second injection flow path 67, and a control unit 90 are provided. The first injection flow path guides a part of the refrigerant flowing from the condenser toward the evaporator to the compressor in a gas phase or a gas-liquid two-phase state. The second injection flow path guides a part of the refrigerant flowing from the condenser toward the evaporator to the suction flow path 27 of the compressor in a liquid phase state. The control unit switches between first injection control for flowing a refrigerant through the first injection flow path and second injection control for flowing the refrigerant through the second injection flow path.
[Selection] Figure 1

Description

  The present invention relates to a refrigeration apparatus, and more particularly to a refrigeration apparatus that uses R32 as a refrigerant.

  Conventionally, a refrigerating apparatus such as an air conditioner that uses R32 as a refrigerant has been proposed. When R32 is used as a refrigerant, the discharge temperature of the compressor tends to be higher than when R410A or R22 is used as a refrigerant. An air conditioner that recognizes this problem and uses the R32 refrigerant to reduce the refrigerant discharge temperature is described in Patent Document 1 (Japanese Patent Laid-Open No. 2009-127902). In this air conditioner, a part of the liquid refrigerant exiting the gas-liquid separator arranged in the high-pressure line is bypassed to the compressor, and the bypass refrigerant is changed to a flash gas state by the internal heat exchanger. . And the bypass refrigerant | coolant used as flash gas is injected, the enthalpy of the refrigerant | coolant of the intermediate pressure state of a compressor is lowered | hung, and the refrigerant | coolant discharge temperature of a compressor is lowered | hung.

  In the air conditioner of Patent Document 1 (Japanese Patent Laid-Open No. 2009-127902), the bypass refrigerant that has become flash gas is injected into the intermediate-pressure refrigerant in the compressor, and the discharge temperature of the compressor is lowered. However, when it is necessary to operate the compressor at a low rotational speed, an operation capacity more than necessary may be output by performing the intermediate injection, and it may be difficult to continue the operation. In such a case, it is conceivable to stop the intermediate injection, but in that case, the discharge temperature of the compressor rises and it may be difficult to continue the operation.

  An object of the present invention is to provide a refrigeration apparatus that uses R32 as a refrigerant, and that can perform injection for suppressing the discharge temperature even when an intermediate injection outputs excessive operating capacity. is there.

  A refrigeration apparatus according to a first aspect of the present invention is a refrigeration apparatus that uses R32 as a refrigerant, and includes a compressor, a condenser, an expansion mechanism, an evaporator, a first injection flow path, and a second injection flow. A road and a control unit. The compressor sucks low-pressure refrigerant from the suction flow path, compresses the refrigerant, and discharges high-pressure refrigerant. The condenser condenses the high-pressure refrigerant discharged from the compressor. The expansion mechanism expands the high-pressure refrigerant that has exited the condenser. The evaporator evaporates the refrigerant expanded by the expansion mechanism. The first injection flow path guides a part of the refrigerant flowing from the condenser toward the evaporator to the compressor in a gas phase or a gas-liquid two-phase state. The second injection flow path guides a part of the refrigerant flowing from the condenser toward the evaporator to the suction flow path in a liquid phase state. The control unit switches between first injection control for flowing a refrigerant through the first injection flow path and second injection control for flowing the refrigerant through the second injection flow path.

  In the refrigeration apparatus according to the present invention, the intermediate injection (first injection control) to the compressor and the liquid injection (second injection control) to the suction flow path of the compressor can be switched and executed. By performing liquid injection into the suction flow path, the discharge temperature can be lowered without increasing the operating capacity. That is, here, even when the intermediate injection outputs an excessive driving capability, the injection for suppressing the discharge temperature is possible. On the other hand, since the intermediate injection to the compressor can also be executed, the driving capacity can be improved by the intermediate injection depending on the situation.

  The refrigeration apparatus according to the second aspect of the present invention is the refrigeration apparatus according to the first aspect, and the control unit switches between the first injection control and the second injection control based on the rotational speed of the compressor. .

  Here, according to the rotation speed of the compressor, intermediate injection (first injection control) to the compressor and liquid injection (second injection control) to the suction passage of the compressor can be executed in a switchable manner.

  The refrigeration apparatus according to the third aspect of the present invention is the refrigeration apparatus according to the second aspect, wherein the control unit switches the first injection control to the second injection control when the rotational speed is smaller than the rotational speed threshold. .

  Here, when the rotation speed of the compressor is smaller than the rotation speed threshold value, in other words, when it is required to suppress the operating capacity to a low level, the liquid injection (second injection control) to the intake passage of the compressor is performed. It is executed and the discharge temperature can be lowered without increasing the driving ability.

  A refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to the third aspect, wherein the control unit includes the second injection flow in the first injection control, the second injection control, and the first injection flow path. Switching to non-injection control in which the refrigerant does not flow in the road. The control unit switches to non-injection control when the discharge temperature of the compressor is lower than the temperature threshold.

  Here, when the discharge temperature of the compressor is lower than the temperature threshold and it is not necessary to lower the temperature of the compressor, injection is not performed, so an unexpected increase in operating capacity and a decrease in operating efficiency are suppressed. Cheap.

  A refrigeration apparatus according to a fifth aspect of the present invention is the refrigeration apparatus according to any one of the first to fourth aspects, further comprising a branch flow path, an opening degree adjusting valve, and an injection heat exchanger. Prepare. The branch channel branches from the main channel connecting the condenser and the evaporator. The opening adjustment valve is provided in the branch flow path and can adjust the opening. The heat exchanger for injection exchanges heat between the refrigerant flowing through the main flow path and the refrigerant passing through the opening adjustment valve of the branch flow path. The first injection channel guides the gas phase or gas-liquid two-phase refrigerant flowing through the branch channel and exiting the heat exchanger for injection to the compressor.

  Here, at the time of intermediate injection (at the time of first injection control), the refrigerant branched from the main flow path connecting the condenser and the evaporator is decompressed by the opening adjustment valve, heated by the injection heat exchanger, and compressed. It is injected into the machine. Therefore, by adjusting and controlling the opening degree of the opening degree adjusting valve, the refrigerant in a desired state (gas-liquid two-layer state or gas phase state (saturated gas or superheated gas)) can be injected into the compressor. In other words, when it is desired to lower the discharge temperature, a wet gas-liquid two-phase refrigerant is injected into the compressor, and when it is desired to improve operating capacity, a superheated gas-phase refrigerant is injected into the compressor. can do.

  A refrigeration apparatus according to a sixth aspect of the present invention is the refrigeration apparatus according to any one of the first to fifth aspects, wherein a gas-liquid separator is provided in the suction flow path. The liquid phase refrigerant guided from the second injection flow path to the suction flow path is supplied between the compressor and the gas-liquid separator.

  Here, at the time of liquid injection into the suction passage of the compressor (during the second injection control), the liquid phase refrigerant is injected downstream from the gas-liquid separator, so the discharge temperature of the compressor is quickly reduced. Can be made.

  In the refrigeration apparatus according to the first aspect of the present invention, the intermediate injection (first injection control) to the compressor and the liquid injection (second injection control) to the suction passage of the compressor can be switched and executed. By performing the liquid injection into the suction passage of the compressor, the discharge temperature can be lowered without increasing the operation capacity. That is, here, even when the intermediate injection outputs an excessive driving capability, the injection for suppressing the discharge temperature is possible. On the other hand, since the intermediate injection to the compressor can also be executed, the driving capacity can be improved by the intermediate injection depending on the situation.

  In the refrigeration apparatus according to the second aspect of the present invention, the intermediate injection into the compressor and the liquid injection into the suction passage of the compressor can be executed in a switchable manner according to the rotation speed of the compressor.

  In the refrigeration apparatus according to the third aspect of the present invention, when the rotation speed of the compressor is smaller than the rotation speed threshold, in other words, when it is required to suppress the driving capacity low, without increasing the driving capacity, The discharge temperature can be lowered.

  In the refrigeration apparatus according to the fourth aspect of the present invention, since injection is not performed when there is no need to lower the temperature of the compressor, an unexpected increase in operating capacity and a decrease in operating efficiency are likely to be suppressed.

  In the refrigeration apparatus according to the fifth aspect of the present invention, the compressor is in a desired state (gas-liquid two-layer state or gas phase state (saturated gas or superheated gas)) during intermediate injection (first injection control). A refrigerant can be injected.

  According to the refrigeration apparatus according to the sixth aspect of the present invention, the discharge temperature of the compressor can be quickly reduced at the time of liquid injection into the suction passage of the compressor (during the second injection control).

It is a figure which shows the refrigerant | coolant piping system | strain of the air conditioning apparatus which concerns on one Embodiment of this invention. It is a control block diagram of the control part of the air conditioning apparatus which concerns on FIG. It is a figure which shows the control flow of the injection control of the air conditioning apparatus which concerns on FIG. It is a figure which shows the refrigerant | coolant piping system | strain of the air conditioning apparatus which concerns on the modification A. It is a figure which shows the refrigerant | coolant piping system of the air conditioning apparatus which concerns on the modification C.

  A refrigeration apparatus according to an embodiment of the present invention will be described with reference to the drawings. Note that the following embodiments can be appropriately changed without departing from the gist of the present invention.

(1) Whole structure of air conditioning apparatus FIG. 1: is a figure which shows the refrigerant | coolant piping system | strain of the air conditioning apparatus 10 which is the freezing apparatus which concerns on one Embodiment of this invention. The air conditioner 10 is a distributed type air conditioner using a refrigerant piping system, and air-conditions each room in a building by performing a vapor compression refrigeration cycle operation. The air conditioner 10 includes an outdoor unit 11 as a heat source unit, an indoor unit 12 as a large number of utilization units, a liquid refrigerant communication tube 13 as a refrigerant communication tube connecting the outdoor unit 11 and the indoor unit 12, and a gas refrigerant. And a communication pipe 14. That is, the refrigerant circuit of the air conditioner 10 shown in FIG. 1 is configured by connecting the outdoor unit 11, the indoor unit 12, and the refrigerant communication tubes 13 and 14.

  The refrigerant circuit shown in FIG. 1 is filled with refrigerant. As will be described later, the refrigerant is compressed, cooled / condensed, decompressed, heated / evaporated, and then compressed again. Cycle operation is performed. R32 is used as the refrigerant. R32 is a low GWP refrigerant with a small global warming potential, and is a kind of HFC refrigerant. Further, as the refrigerating machine oil, an ether-based synthetic oil having some compatibility with R32 is used.

(2) Detailed Configuration of Air Conditioner (2-1) Indoor Unit The indoor unit 12 is installed on the ceiling or side wall of each room, and is connected to the outdoor unit 11 via the refrigerant communication tubes 13 and 14. . The indoor unit 12 mainly includes an indoor expansion valve 42 that is a decompressor and an indoor heat exchanger 50 that is a use-side heat exchanger.

  The indoor expansion valve 42 is an expansion mechanism for decompressing the refrigerant, and is an electric valve capable of adjusting the opening degree. The indoor expansion valve 42 has one end connected to the liquid refrigerant communication tube 13 and the other end connected to the indoor heat exchanger 50.

  The indoor heat exchanger 50 is a heat exchanger that functions as a refrigerant evaporator or a condenser. The indoor heat exchanger 50 has one end connected to the indoor expansion valve 42 and the other end connected to the gas refrigerant communication pipe 14.

  The indoor unit 12 includes an indoor fan 55 for sucking indoor air into the unit and supplying it to the room again, and exchanges heat between the indoor air and the refrigerant flowing through the indoor heat exchanger 50.

  In addition, the indoor unit 12 includes an indoor control unit 92 that controls various sensors and the operation of each unit constituting the indoor unit 12. The indoor control unit 92 includes a microcomputer, a memory, and the like provided for controlling the indoor unit 12, and controls with a remote controller (not shown) for individually operating the indoor unit 12. Exchange of a signal etc. is performed, and exchange of a control signal etc. is performed via the transmission line 93 with the outdoor control part 91 of the outdoor unit 11 mentioned later.

(2-2) Outdoor unit The outdoor unit 11 is installed outside the building where the room where the indoor unit 12 is located or in the basement of the building, and is connected to the indoor unit 12 via the refrigerant communication pipes 13 and 14. Has been. The outdoor unit 11 mainly includes a compressor 20, a four-way switching valve 15, an outdoor heat exchanger 30, an outdoor expansion valve 41, a bridge circuit 70, a high-pressure receiver 80, and a first injection motor operated valve 63. The injection heat exchanger 64, the second injection motor-operated valve 68, the accumulator 28, the liquid side shut-off valve 17, and the gas side shut-off valve 18 are provided.

  The compressor 20 is a hermetic compressor driven by a compressor motor. The compressor 20 (compressor motor) is inverter-controlled. The number of the compressors 20 is only one in the present embodiment, but is not limited to this, and two or more compressors may be connected in parallel according to the number of indoor units 12 connected. The compressor 20 sucks the gas refrigerant from the suction passage 27 via the accumulator 28 as a gas-liquid separator. A discharge pressure sensor for detecting the discharge refrigerant pressure and a discharge temperature sensor 95 for detecting the discharge refrigerant temperature are attached to the refrigerant pipe 29 on the discharge side of the compressor 20. In addition, a suction temperature sensor that detects the temperature of the refrigerant sucked into the compressor 20 is attached to the suction flow path 27. The compressor 20 includes an intermediate injection port 23. The intermediate injection port 23 will be described later.

  The four-way switching valve 15 is a mechanism for switching the direction of refrigerant flow. During the cooling operation, the outdoor heat exchanger 30 functions as a refrigerant condenser compressed by the compressor 20 and the indoor heat exchanger 50 functions as a refrigerant evaporator cooled in the outdoor heat exchanger 30. In addition, the four-way switching valve 15 connects the refrigerant pipe 29 on the discharge side of the compressor 20 and one end of the outdoor heat exchanger 30, and the suction flow path 27 (including the accumulator 28) on the suction side of the compressor 20. Are connected to the gas-side closing valve 18 (see the solid line of the four-way switching valve 15 in FIG. 1). Further, during the heating operation, the indoor heat exchanger 50 functions as a refrigerant condenser compressed by the compressor 20, and the outdoor heat exchanger 30 functions as a refrigerant evaporator cooled in the indoor heat exchanger 50. For this purpose, the four-way switching valve 15 connects the refrigerant pipe 29 on the discharge side of the compressor 20 and the gas-side shut-off valve 18 and connects the suction flow path 27 and one end of the outdoor heat exchanger 30 ( (Refer to the broken line of the four-way switching valve 15 in FIG. 1). In the present embodiment, the four-way switching valve 15 is a four-way valve connected to the suction flow path 27, the refrigerant pipe 29 on the discharge side of the compressor 20, the outdoor heat exchanger 30, and the gas side shut-off valve 18.

  The outdoor heat exchanger 30 is a heat exchanger that functions as a refrigerant condenser or evaporator. One end of the outdoor heat exchanger 30 is connected to the four-way switching valve 15, and the other end is connected to the outdoor expansion valve 41.

  The outdoor unit 11 has an outdoor fan 35 for sucking outdoor air into the unit and discharging it to the outdoor again. The outdoor fan 35 exchanges heat between the outdoor air and the refrigerant flowing through the outdoor heat exchanger 30, and is driven to rotate by an outdoor fan motor. The heat source of the outdoor heat exchanger 30 is not limited to outdoor air, and may be another heat medium such as water.

  The outdoor expansion valve 41 is an expansion mechanism for decompressing the refrigerant, and is an electric valve capable of adjusting the opening degree. One end of the outdoor expansion valve 41 is connected to the outdoor heat exchanger 30, and the other end is connected to the bridge circuit 70.

  The bridge circuit 70 has four check valves 71, 72, 73 and 74. The inlet check valve 71 is a check valve that allows only the flow of refrigerant from the outdoor heat exchanger 30 toward the high-pressure receiver 80. The outlet check valve 72 is a check valve that allows only the flow of refrigerant from the high-pressure receiver 80 toward the indoor heat exchanger 50. The inlet check valve 73 is a check valve that allows only the flow of refrigerant from the indoor heat exchanger 50 toward the high-pressure receiver 80. The outlet check valve 74 is a check valve that allows only a refrigerant flow from the high-pressure receiver 80 to the outdoor heat exchanger 30 via the outdoor expansion valve 41. In other words, the inlet check valves 71 and 73 function to flow a refrigerant from one of the outdoor heat exchanger 30 and the indoor heat exchanger 50 to the high-pressure receiver 80, and the outlet check valves 72 and 74 are connected to the outdoor from the high-pressure receiver 80. It fulfills the function of flowing the refrigerant to the other of the heat exchanger 30 and the indoor heat exchanger 50.

  The high-pressure receiver 80 is a container that functions as a refrigerant storage tank, and is provided between the outdoor expansion valve 41 and the liquid-side closing valve 17. The high-pressure receiver 80 into which high-pressure refrigerant flows during both the cooling operation and the heating operation keeps the temperature of the surplus refrigerant stored therein relatively high. Therefore, the surplus refrigerant including the refrigerating machine oil is separated into two layers and the refrigerating machine oil is placed on the upper part. There is no problem of gathering.

  An injection heat exchanger 64 is provided between the outlet of the high pressure receiver 80 and the outlet check valves 72 and 74 of the bridge circuit 70. A branch pipe 62 is branched from a part of the main refrigerant flow path 11a that connects the outlet of the high-pressure receiver 80 and the heat exchanger 64 for injection. Furthermore, a second injection flow path 67 is branched from a part of the main refrigerant flow path 11a that connects the downstream side of the heat exchanger for injection 64 and the bridge circuit 70. The main refrigerant flow path 11 a is a main flow path for liquid refrigerant that connects the outdoor heat exchanger 30 and the indoor heat exchanger 50. The high-pressure receiver 80 is provided between the outdoor expansion valve 41 and the liquid side shut-off valve 17 in the main refrigerant flow path 11a.

  The branch pipe 62 is provided with a first injection motor-operated valve 63 whose opening degree can be adjusted. The branch pipe 62 is connected to the second flow path 64 b of the injection heat exchanger 64. That is, when the first injection motor-operated valve 63 is open, the refrigerant branched from the main refrigerant channel 11 a to the branch pipe 62 is decompressed by the first injection motor-operated valve 63, and the injection heat exchanger 64 has the first pressure. It flows into the two flow paths 64b. Note that the second flow path 64 b of the heat exchanger for injection 64 constitutes a part of the branch pipe 62.

  The refrigerant that has been depressurized by the first injection motor-operated valve 63 and has flowed into the second flow path 64b of the injection heat exchanger 64 exchanges heat with the refrigerant that flows through the first flow path 64a of the injection heat exchanger 64. The first flow path 64a of the heat exchanger for injection 64 constitutes a part of the main refrigerant flow path 11a. The refrigerant heat-exchanged by the injection heat exchanger 64 is guided to the compressor 20 by the first injection flow path 65. The first injection flow path 65 is a pipe that connects a portion of the branch pipe 62 on the downstream side of the heat exchanger 64 for injection and the intermediate injection port 23 of the compressor 20. An injection temperature sensor 96 that detects the temperature of the refrigerant after heat exchange that has passed through the second flow path 64 b of the injection heat exchanger 64 is attached to the first injection flow path 65.

  The heat exchanger for injection 64 is an internal heat exchanger adopting a double tube structure, and as described above, from the refrigerant flowing through the main refrigerant channel 11a that is the main channel, and the main refrigerant channel 11a for injection. Heat exchange is performed with the refrigerant for injection flowing through the branched branch pipe 62. One end of the first flow path 64 a of the injection heat exchanger 64 is connected to the outlet of the high-pressure receiver 80, and the other end is connected to the outlet check valves 72 and 74 of the bridge circuit 70.

  The second injection flow path 67 connects the main refrigerant flow path 11 a and the suction flow path 27 of the compressor 20. More specifically, the second injection flow path 67 includes a part of the main refrigerant flow path 11 a connecting the downstream side of the injection heat exchanger 64 and the bridge circuit 70, and a downstream side of the accumulator 28 of the suction flow path 27. Connect. The second injection flow path 67 is provided with a second injection motor-operated valve 68 whose opening degree can be adjusted. When the second injection motor-operated valve 68 is open, part of the liquid-phase refrigerant flowing through the main refrigerant channel 11a is guided to the suction channel 27 via the second injection channel 67, and the compressor 20 is inhaled.

  The liquid side closing valve 17 is a valve to which a liquid refrigerant communication tube 13 for exchanging refrigerant between the outdoor unit 11 and the indoor unit 12 is connected. The gas-side closing valve 18 is a valve to which a gas refrigerant communication pipe 14 for exchanging refrigerant between the outdoor unit 11 and the indoor unit 12 is connected, and is connected to the four-way switching valve 15. Here, the liquid side closing valve 17 and the gas side closing valve 18 are three-way valves provided with service ports.

  The accumulator 28 is an example of a gas-liquid separator and is disposed in the suction flow path 27 between the four-way switching valve 15 and the compressor 20. The accumulator 28 functions to separate the liquid component and the gas component of the refrigerant therein and prevent the liquid refrigerant from being sucked into the compressor 20.

  As described above, the compressor 20 is provided with the intermediate injection port 23. The intermediate injection port 23 is a refrigerant introduction port for flowing a refrigerant from the outside into an intermediate pressure refrigerant in the middle of compression in the compressor 20. A first injection flow path 65 is connected to the intermediate injection port 23. The first injection flow path 65 is a pipe that connects a portion of the branch pipe 62 on the downstream side of the heat exchanger for injection 64 and the intermediate injection port 23. When the first injection solenoid valve 63 is open, the refrigerant that has flowed through the branch pipe 62 and has undergone heat exchange by the injection heat exchanger 64 is guided to the intermediate injection port 23 by the first injection flow path 65. Intermediate injection is performed. The first injection flow path 65 is connected to a refrigerant pipe connecting the discharge port of the low-stage compressor and the suction port of the high-stage compressor, instead of replacing the compressor 20 with two compressors arranged in series. It is also possible to adopt a configuration in which

  The outdoor unit 11 includes various sensors and an outdoor control unit 91. The outdoor control unit 91 includes a microcomputer, a memory, and the like provided to control the outdoor unit 11, and controls signals and the like via a transmission line 93 with the indoor control unit 92 of the indoor unit 12. Exchange. As the various sensors, the above-described discharge pressure sensor, discharge temperature sensor 95, suction temperature sensor, injection temperature sensor 96, and the like are provided.

(2-3) Refrigerant communication pipes The refrigerant communication pipes 13 and 14 are refrigerant pipes that are constructed on site when the outdoor unit 11 and the indoor unit 12 are installed at the installation location.

(2-4) Control Unit A control unit 90 as a control unit that performs various operation controls of the air conditioning apparatus 10 is performed by an outdoor control unit 91 and an indoor control unit 92 that are connected via a transmission line 93 as illustrated in FIG. It is configured. As shown in FIG. 2, the control unit 90 receives detection signals from the various sensors 95, 96,..., And based on these detection signals, the various devices 20, 35, 41, 55, 63, 68. , ... are controlled.

  The control unit 90 includes a cooling operation control unit 90a for performing a cooling operation using the indoor heat exchanger 50 as an evaporator, and a heating operation control for performing a heating operation using the indoor heat exchanger 50 as a condenser. The unit 90b includes an injection control unit 90c for performing injection control in the cooling operation and the heating operation.

(3) Operation | movement of an air conditioning apparatus Next, operation | movement of the air conditioning apparatus 10 which concerns on this embodiment is demonstrated. In addition, control in various operations described below is performed by the control unit 90 that functions as an operation control unit.

(3-1) Basic operation of cooling operation At the time of cooling operation, the four-way switching valve 15 is in the state indicated by the solid line in FIG. 1, that is, the discharged gas refrigerant from the compressor 20 flows to the outdoor heat exchanger 30, and Then, the suction flow path 27 is connected to the gas side closing valve 18. The outdoor expansion valve 41 is fully opened, and the opening degree of the indoor expansion valve 42 is adjusted. The closing valves 17 and 18 are in an open state.

  In this state of the refrigerant circuit, the high-pressure gas refrigerant discharged from the compressor 20 is sent to the outdoor heat exchanger 30 that functions as a refrigerant condenser via the four-way switching valve 15, and is sent by the outdoor fan 35. It is cooled by exchanging heat with the supplied outdoor air. The high-pressure refrigerant that has been cooled and liquefied in the outdoor heat exchanger 30 becomes supercooled by the injection heat exchanger 64 and is sent to each indoor unit 12 via the liquid refrigerant communication tube 13. The refrigerant sent to each indoor unit 12 is reduced in pressure by the indoor expansion valve 42 to become a low-pressure gas-liquid two-phase refrigerant, and exchanges heat with indoor air in the indoor heat exchanger 50 functioning as an evaporator of the refrigerant. Then, it evaporates and becomes a low-pressure gas refrigerant. Then, the low-pressure gas refrigerant heated in the indoor heat exchanger 50 is sent to the outdoor unit 11 via the gas refrigerant communication pipe 14 and is sucked into the compressor 20 again via the four-way switching valve 15. . In this way, the room is cooled.

  When only some of the indoor units 12 are in operation, the indoor expansion valve 42 of the stopped indoor units 12 is set to a stop opening (for example, fully closed). In this case, the refrigerant hardly passes through the indoor unit 12 that is not operating, and only the indoor unit 12 that is operating is cooled.

(3-2) Basic Operation of Heating Operation During the heating operation, the four-way switching valve 15 is in the state indicated by the broken line in FIG. 1, that is, the refrigerant pipe 29 on the discharge side of the compressor 20 is connected to the gas side shut-off valve 18. In addition, the suction flow path 27 is connected to the outdoor heat exchanger 30. The opening degree of the outdoor expansion valve 41 and the indoor expansion valve 42 is adjusted. The closing valves 17 and 18 are in an open state.

  In the state of this refrigerant circuit, the high-pressure gas refrigerant discharged from the compressor 20 is sent to each indoor unit 12 via the four-way switching valve 15 and the gas refrigerant communication pipe 14. The high-pressure gas refrigerant sent to each indoor unit 12 passes through the indoor expansion valve 42 after being cooled by exchanging heat with indoor air in the indoor heat exchanger 50 functioning as a refrigerant condenser. Then, it is sent to the outdoor unit 11 via the liquid refrigerant communication tube 13. When the refrigerant is cooled by exchanging heat with room air, the room air is heated. The high-pressure refrigerant sent to the outdoor unit 11 becomes a supercooled state in the injection heat exchanger 64 and is decompressed by the outdoor expansion valve 41 to become a low-pressure gas-liquid two-phase state refrigerant as a refrigerant evaporator. It flows into the functioning outdoor heat exchanger 30. The low-pressure gas-liquid two-phase refrigerant flowing into the outdoor heat exchanger 30 is heated by exchanging heat with the outdoor air supplied by the outdoor fan 35 and evaporated to become a low-pressure refrigerant. The low-pressure gas refrigerant exiting the outdoor heat exchanger 30 is again sucked into the compressor 20 via the four-way switching valve 15. In this way, the room is heated.

(3-3) Injection Control in Each Operation The injection control unit 90c, which is one of the functional units of the control unit 90, reduces the discharge temperature Tdi of the compressor 20 and improves the operation capability during cooling operation and heating operation. For this purpose, intermediate injection or inhalation injection is performed.

  In the intermediate injection, a part of the refrigerant flowing in the main refrigerant flow path 11a from the condenser toward the evaporator is branched and flowed to the first injection flow path 65 to compress the refrigerant in a gas phase or a gas-liquid two-phase state. Injection into the intermediate injection port 23 of the machine 20. In the suction injection, a part of the liquid-phase refrigerant flowing through the main refrigerant flow path 11a from the condenser toward the evaporator is branched, flows into the second injection flow path 67, and is injected into the suction flow path 27. It is. Both the intermediate injection and the suction injection have an effect of lowering the discharge temperature Tdi in the compressor 20 in which the discharge temperature Tdi tends to increase because R32 is used as a refrigerant. Further, the intermediate injection further has an effect of increasing the driving ability.

  The injection control unit 90c switches and executes the first injection control for performing the intermediate injection or the second injection control for performing the suction injection according to the rotation speed (or frequency) of the compressor 20 controlled by the inverter. .

  Further, when neither the first injection control nor the second injection control is necessary, the injection control is stopped. That is, the injection control unit 90c does not perform the first injection control, the second injection control, and the injection at all (no refrigerant flows through either the first injection flow path 65 or the second injection flow path 67). Is selectively performed.

  FIG. 3 shows a flow of injection control by the injection control unit 90c. First, in step S1, it is determined whether the rotational speed of the compressor 20 is larger or smaller than a predetermined rotational speed threshold. The predetermined rotation speed threshold value is, for example, a considerably small rotation speed that cannot be set to a lower rotation speed, or a value that reduces the efficiency of the compressor motor when the rotation speed is decreased. Set to

  When it is determined in step S1 that the rotation speed of the compressor 20 is equal to or higher than the rotation speed threshold value, the first injection control is performed. In the first injection control, the first injection motor-operated valve 63 is opened, and the second injection motor-operated valve 68 is closed. The opening degree of the first injection motor-operated valve 63 will be described later.

  In the first injection control, in step S2, it is determined whether or not the discharge temperature Tdi of the refrigerant discharged from the compressor 20 detected by the discharge temperature sensor 95 is higher than the first upper limit value. For example, the first upper limit value is set to 95 ° C.

  When the discharge temperature Tdi is lower than the first upper limit value, in step S3, based on the temperature Tsh of the injection refrigerant downstream of the injection heat exchanger 64 detected by the injection temperature sensor 96, The opening degree of the first injection motor-operated valve 63 is adjusted. The injection control unit 90c is arranged so that the intermediately injected gas refrigerant becomes a superheated gas, that is, a gas-phase gas refrigerant with a superheat degree of several degrees C. flows into the first injection flow path 65. The opening degree of the electric valve 63 for 1 injection is controlled. Thereby, appropriate capability improvement is achieved.

  On the other hand, when it is determined in step S2 that the discharge temperature Tdi is higher than the first upper limit value, in step S4, based on the discharge temperature Tdi of the refrigerant discharged from the compressor 20, the first injection motor-operated valve 63 is operated. The opening is controlled. Here, the wetness control for moistening the gas refrigerant to be subjected to the intermediate injection is performed so that the discharge temperature Tdi is lower than the first upper limit value. That is, the injection control unit 90c controls the opening degree of the first injection motor-operated valve 63 so that the intermediately injected gas refrigerant becomes a gas-liquid two-phase flash gas in order to enhance the cooling effect of the intermediate injection.

  When the rotational speed of the compressor 20 is lower than the rotational speed threshold in step S1, the process proceeds to step S5, and it is determined whether or not the discharge temperature Tdi of the refrigerant discharged from the compressor 20 is higher than the first upper limit value. .

  Here, when the discharge temperature Tdi is lower than the first upper limit value, it is not necessary to cool the compressor 20 and there is no merit of further reducing the rotation speed of the compressor 20, so that the intermediate injection is also sucked. No injection is performed (the description is omitted in the flow of FIG. 3). That is, when the discharge temperature Tdi is lower than the first upper limit value, the injection control unit 90c closes both the first injection motor-operated valve 63 and the second injection motor-operated valve 68, and performs non-injection control.

  On the other hand, if it is determined in step S5 that the discharge temperature Tdi is higher than the first upper limit value, the second injection control is performed. In the second injection control, the first injection motor-operated valve 63 is closed, and the second injection motor-operated valve 68 is opened.

  The opening degree of the second injection motor-operated valve 68 is controlled based on the discharge temperature Tdi of the refrigerant discharged from the compressor 20. Here, the amount of the liquid phase refrigerant to be sucked and injected is adjusted so that the discharge temperature Tdi is lower than the first upper limit value. The opening degree of the second injection motor-operated valve 68 is adjusted so that the compressor 20 does not cause liquid compression.

  When the discharge temperature Tdi of the refrigerant discharged from the compressor 20 detected by the discharge temperature sensor 95 exceeds a second upper limit value that is higher than the first upper limit value, the drooping control of the compressor 20 starts and the rotation speed is forced. When the detected temperature Tdi exceeds the third upper limit value that is higher than the second upper limit value, the control unit 90 issues a stop command for the compressor 20.

(4) Features of the air conditioner (4-1)
The air conditioning apparatus 10 according to the present embodiment is an air conditioning apparatus 10 as a refrigeration apparatus that uses R32 as a refrigerant. The air conditioner 10 includes a compressor 20, an outdoor heat exchanger 30 and an indoor heat exchanger 50 as a condenser or an evaporator, an outdoor expansion valve 41 and an indoor expansion valve 42 as an expansion mechanism, and a first injection flow path. A first injection flow path 65 as a second injection flow path 67 as a second injection flow path, and a control unit 90. The compressor 20 sucks the low-pressure refrigerant from the suction flow path 27, compresses the refrigerant, and discharges the high-pressure refrigerant. The outdoor heat exchanger 30 (cooling) or the indoor heat exchanger 50 (heating) as a condenser condenses the high-pressure refrigerant discharged from the compressor 20. The outdoor expansion valve 41 and the indoor expansion valve 42 as expansion mechanisms expand the high-pressure refrigerant that has exited the outdoor heat exchanger 30 or the indoor heat exchanger 50 as a condenser. The indoor heat exchanger 50 (during cooling) or the outdoor heat exchanger 30 (during heating) as an evaporator evaporates the refrigerant expanded by the expansion mechanism (outdoor expansion valve 41, indoor expansion valve 42). The first injection flow path 65 flows from the condenser toward the evaporator (from the outdoor heat exchanger 30 to the indoor heat exchanger 50 during cooling and from the indoor heat exchanger 50 to the outdoor heat exchanger 30 during heating). A part of the refrigerant is guided to the compressor 20 in a gas phase or a gas-liquid two-phase state. The second injection channel 67 guides a part of the refrigerant flowing from the condenser toward the evaporator to the suction channel 27 in a liquid phase state. The control unit 90 switches between first injection control for flowing the refrigerant through the first injection flow path 65 and second injection control for flowing the refrigerant through the second injection flow path 67.

  Here, the intermediate injection (first injection control) to the compressor 20 and the liquid injection (second injection control) to the suction flow path 27 of the compressor 20 can be switched and executed. By performing the liquid injection into the flow path 27, the discharge temperature Tdi can be lowered without increasing the operating capacity. That is, in this case, even when an excessive operating capacity is output in the intermediate injection, the injection for suppressing the discharge temperature Tdi is possible, and the protection control (the drooping control) of the compressor 20 due to the increase in the discharge temperature Tdi. , Forced stop) can be suppressed. On the other hand, since the intermediate injection to the compressor 20 can also be executed, the driving capacity can be improved by the intermediate injection depending on the situation.

(4-2)
In the air conditioning apparatus 10 according to the present embodiment, the control unit 90 switches between the first injection control and the second injection control based on the rotation speed of the compressor 20.

  Thereby, according to the rotation speed (operation capability) of the compressor 20, the intermediate injection (1st injection control) to the compressor 20, and the liquid injection (2nd injection control) to the suction flow path 27 of the compressor 20 are carried out. Can be executed in a switchable manner.

(4-3)
In the air conditioning apparatus 10 according to the present embodiment, the control unit 90 switches the first injection control to the second injection control when the rotational speed is smaller than the rotational speed threshold.

  Here, when the rotation speed of the compressor 20 is smaller than the rotation speed threshold value, in other words, when it is required to suppress the operation capacity to be low, liquid injection (second injection control) into the suction flow path 27 of the compressor 20 is required. ) Is executed, and the discharge temperature Tdi can be lowered without increasing the driving capability.

(4-4)
In the air conditioning apparatus 10 according to the present embodiment, the control unit 90 performs the first injection control, the second injection control, and the non-injection in which the refrigerant does not flow into the first injection flow path 65 and the second injection flow path 67. Switch between control. The controller 90 switches to non-injection control when the discharge temperature Tdi of the compressor 20 is smaller than the first upper limit value as the temperature threshold.

  Here, when the discharge temperature Tdi of the compressor 20 is lower than the temperature threshold value and it is not necessary to lower the temperature of the compressor 20, it is possible to switch to non-injection control without performing injection.

  Further, here, the control unit 90 performs non-injection control when the discharge temperature Tdi of the compressor 20 is smaller than the first upper limit value as the temperature threshold value and the rotational speed of the compressor 20 is smaller than the rotational speed threshold value. Switch.

  That is, when it is not necessary to lower the temperature of the compressor 20 and it is not necessary to increase the operating capacity, injection is not performed, so that an unexpected increase in operating capacity and a decrease in operating efficiency are easily suppressed. .

(4-5)
The air conditioner 10 according to the present embodiment includes a branch pipe 62 as a branch flow path, a first injection motor operated valve 63 as an opening adjustment valve, and an injection heat exchanger 64. The branch pipe 62 branches from the main refrigerant flow path 11a that connects the condenser (the outdoor heat exchanger 30 or the indoor heat exchanger 50) and the evaporator (the indoor heat exchanger 50 or the outdoor heat exchanger 30). The first injection motor-operated valve 63 is provided in the branch pipe 62, and the opening degree can be adjusted. The heat exchanger for injection 64 exchanges heat between the refrigerant flowing through the main refrigerant flow path 11 a and the refrigerant that has passed through the first injection motor-operated valve 63 of the branch pipe 62. The first injection flow path 65 guides the gas-phase or gas-liquid two-phase refrigerant flowing through the branch pipe 62 and exiting the injection heat exchanger 64 to the compressor 20.

  Here, at the time of intermediate injection into the compressor (at the time of the first injection control), the condenser and the evaporator are connected (the outdoor heat exchanger 30 and the indoor heat exchanger 50 are connected), and the main refrigerant flow path 11a is branched. The refrigerant is decompressed by the first injection solenoid valve 63, heated by the injection heat exchanger 64, and injected into the compressor 20. Therefore, by adjusting and controlling the opening degree of the first injection solenoid valve 63, the compressor 20 is injected with a refrigerant in a desired state (gas-liquid two-layer state or gas phase state (saturated gas or superheated gas)). be able to. That is, in particular, when it is desired to lower the discharge temperature, a humid gas-liquid two-phase refrigerant is supplied to the compressor 20, and when an improvement in operating capability is desired, a superheated gas-phase refrigerant is supplied to the compressor 20. Can be injected.

(4-6)
In the air conditioning apparatus 10 according to the present embodiment, the suction flow path 27 is provided with an accumulator 28 as a gas-liquid separator. The liquid phase refrigerant guided from the second injection channel 67 to the suction channel 27 is supplied between the compressor 20 and the accumulator 28.

  Here, at the time of liquid injection into the suction flow path 27 of the compressor 20 (during the second injection control), liquid phase refrigerant is injected downstream from the accumulator 28. That is, since the liquid-phase refrigerant is directly injected into the compressor, the compressor 20 can be quickly cooled.

  Here, at the time of liquid injection into the suction passage of the compressor (during the second injection control), the liquid phase refrigerant is injected downstream from the accumulator 28, so that the liquid phase refrigerant is immediately supplied to the compressor 20. Is done. As a result, the discharge temperature of the compressor 20 can be quickly reduced.

(5) Modifications Modifications of the present embodiment are shown below. A plurality of modified examples may be appropriately combined.

(5-1) Modification A
In the air conditioning apparatus 10 of the above-described embodiment, a configuration in which the refrigerant for intermediate injection is supplied to the first injection flow path 65 from the branch pipe 62 branched from the main refrigerant flow path 11a is adopted. Instead, as in the air conditioner 110 (see FIG. 4), the gas component of the refrigerant accumulated in the high-pressure receiver 180 provided in the main refrigerant flow path 111a is taken out by the bypass flow path 182 and is extracted from the bypass flow path 182. A configuration in which a refrigerant for injection is supplied to the first injection flow path 65 can also be adopted.

  Moreover, in the air conditioning apparatus 10 of the said embodiment, although the structure which supplies the refrigerant | coolant for liquid injection from the 2nd injection flow path 67 branched from the main refrigerant flow path 11a is taken, it replaces with this and air-conditioning is carried out. Like the device 110, the liquid-phase refrigerant accumulated in the high-pressure receiver 180 can be taken out by the second injection flow path 167 and used for suction injection (see FIG. 4).

  In addition, the air conditioning apparatus 110 which concerns on the modification A replaces the outdoor unit 11 of the air conditioning apparatus 10 of the said embodiment with the outdoor unit 111. FIG. The outdoor unit 111 removes the bridge circuit 70, the high-pressure receiver 80, the branch pipe 62, the first injection motor-operated valve 63, and the injection heat exchanger 64 from the above-described outdoor unit 11, and instead, the high-pressure receiver 180, bypass flow A path 182 and a first injection bypass electric valve 184 are provided. In the outdoor unit 111, the devices having the same reference numerals as those of the outdoor unit 11 are the same as the devices of the above-described embodiment, and thus the description thereof is omitted.

  The high-pressure receiver 180 is a container provided in a part of the main refrigerant flow path 111 a that connects the outdoor expansion valve 41 and the liquid side closing valve 17. The main refrigerant flow path 111 a is a main flow path for liquid refrigerant that connects the outdoor heat exchanger 30 and the indoor heat exchanger 50. The high-pressure receiver 180 into which high-pressure refrigerant flows during both the cooling operation and the heating operation keeps the temperature of the excess refrigerant stored therein relatively high. There is no problem of gathering. In the internal space of the high-pressure receiver 180, liquid refrigerant is normally present in the lower portion and gas refrigerant is present in the upper portion, and a bypass flow path 182 extends from the upper portion of the internal space toward the compressor 20. A second injection flow path 167 extends from the lower part of the internal space toward the compressor 20.

  The bypass flow path 182 is a pipe that plays a role of guiding the gas component of the refrigerant accumulated in the high-pressure receiver 180 to the compressor 20. The bypass passage 182 is provided with an injection bypass electric valve 184 whose opening degree can be adjusted. During the first injection control, the injection bypass electric valve 184 is opened (the second injection electric valve 68 is closed), and intermediate injection is performed.

  The second injection flow path 167 is a pipe that plays a role of guiding the liquid component of the refrigerant accumulated in the high-pressure receiver 180 to the suction flow path 27 of the compressor 20. At the time of the second injection control, the second injection motor-operated valve 68 provided in the second injection channel 167 is opened (the injection bypass motor-operated valve 184 is closed), and a liquid-phase refrigerant flows into the second injection channel 167, Inhalation injection is made.

  In the air conditioner 110 according to Modification A, the refrigerant guided to the compressor 20 via the first injection flow path 65 becomes the gas component of the refrigerant that accumulates inside the high-pressure receiver 180. That is, the saturated gas of the refrigerant in the high-pressure receiver 180 flows to the compressor 20. In the air conditioner 110, in the same way as the air conditioner 10 of the above embodiment, the first injection control and the second injection control can be selectively used, and the injection heat exchanger 64 of the above embodiment becomes unnecessary. The manufacturing cost of the air conditioner 110 can be kept small. On the other hand, since the wet gas cannot be subjected to intermediate injection and is basically injected by saturated gas, the effect of reducing the discharge temperature Tdi of the compressor 20 by the intermediate injection cannot be expected so much.

(5-2) Modification B
In the above embodiment, if the rotation speed of the compressor 20 is equal to or higher than the rotation speed threshold value, intermediate injection is performed regardless of the magnitude relationship between the discharge temperature Tdi and the first upper limit value. However, the present invention is not limited to this. When the discharge temperature Tdi is smaller than the first upper limit value (in the case of step S3 in FIG. 3), the intermediate injection may not be performed and the non-injection control may be performed.

  That is, both the intermediate injection and the suction injection may be executed mainly for cooling the compressor 20.

(5-3) Modification C
In the above embodiment, during the second injection control (inhalation injection), the liquid-phase refrigerant is injected downstream of the accumulator 28. However, the present invention is not limited to this, and the air conditioner 210 in FIG. In addition, a liquid-phase refrigerant may be injected upstream of the accumulator 28.

  In addition, the air conditioning apparatus 210 which concerns on the modification C replaces the outdoor unit 11 of the air conditioning apparatus 10 of the said embodiment with the outdoor unit 211. FIG. The outdoor unit 211 is different only in the connection position between the outdoor unit 11 and the suction flow path 27 of the second injection flow path 267. In the outdoor unit 211, the devices denoted by the same reference numerals as those of the outdoor unit 11 are the same as the devices of the above-described embodiment, and thus description thereof is omitted.

  Here, since the liquid-phase refrigerant flowing through the second injection flow path 267 is sucked into the compressor 20 through the accumulator 28, the possibility of causing liquid compression in the compressor 20 can be reduced. However, in order to cool the compressor 20 quickly, it is desirable that the refrigerant is supplied to the downstream side of the accumulator 28.

(5-4) Modification D
In the above embodiment, the accumulator 28 is provided in the suction flow path 27, but the present invention is not limited to this, and the accumulator 28 may not be provided.

10, 110, 210 Air conditioning equipment (refrigeration equipment)
11a Main refrigerant channel (main channel)
20 Compressor 27 Suction channel 28 Accumulator (gas-liquid separator)
30 Outdoor heat exchanger (condenser, evaporator)
41 Outdoor expansion valve (expansion mechanism)
42 Indoor expansion valve (expansion mechanism)
50 Indoor heat exchanger (evaporator, condenser)
62 Branch pipe (branch flow path)
63 Electric valve for first injection (opening adjustment valve)
64 Heat Exchanger 65 for Injection First Injection Channel 67, 167, 267 Second Injection Channel 90 Control Unit

JP 2009-127902 A

Claims (6)

In a refrigeration system using R32 as a refrigerant,
A compressor (20) for sucking low-pressure refrigerant from the suction flow path (27), compressing the refrigerant, and discharging high-pressure refrigerant;
A condenser (30, 50) for condensing the high-pressure refrigerant discharged from the compressor;
An expansion mechanism (41, 42) for expanding the high-pressure refrigerant exiting the condenser;
An evaporator (50, 30) for evaporating the refrigerant expanded by the expansion mechanism;
A first injection flow path (65) for guiding a part of the refrigerant flowing from the condenser toward the evaporator to the compressor in a gas phase or a gas-liquid two-phase state;
A second injection flow path (67, 167, 267) for guiding a part of the refrigerant flowing from the condenser toward the evaporator to the suction flow path in a liquid phase state;
A control unit (90) for switching between a first injection control for flowing a refrigerant through the first injection flow path and a second injection control for flowing a refrigerant through the second injection flow path;
A refrigeration apparatus (10, 110, 210). The refrigeration apparatus according to claim 1, wherein the control unit switches between the first injection control and the second injection control based on a rotation speed of the compressor. The controller switches the first injection control to the second injection control when the rotational speed is smaller than a rotational speed threshold;
The refrigeration apparatus according to claim 2. The control unit switches between the first injection control, the second injection control, and the non-injection control in which the refrigerant does not flow into the first injection channel or the second injection channel,
When the discharge temperature of the compressor is lower than the temperature threshold, switch to non-injection control,
The refrigeration apparatus according to claim 3. A branch channel (62) branched from a main channel (11a) connecting the condenser and the evaporator;
An opening adjustment valve (63) provided in the branch flow path and capable of adjusting the opening;
An injection heat exchanger (64) for exchanging heat between the refrigerant flowing through the main flow path and the refrigerant that has passed through the opening adjustment valve of the branch flow path;
Further comprising
The first injection flow path guides the gas-phase or gas-liquid two-phase refrigerant flowing through the branch flow path and exiting the injection heat exchanger to the compressor.
The refrigeration apparatus (10, 210) according to any one of claims 1 to 4. The suction flow path is provided with a gas-liquid separator (28),
Liquid phase refrigerant guided from the second injection flow path to the suction flow path is supplied between the compressor and the gas-liquid separator.
The refrigeration apparatus (10, 110) according to any one of claims 1 to 5.

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