JP2008096051A - Coolant charged amount determining method and coolant leakage detecting method for multiple type air conditioning system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a coolant charged amount determining method and a coolant leakage detecting method for a multiple type air conditioning system providing charging of coolant of a proper amount matching respective multiple type air conditioning systems by accurately judging a gas low and/or overcharging of a coolant charged amount. <P>SOLUTION: The coolant charged amount determining method is for the multiple type air conditioning system 1 composed of an outdoor unit 2, and a plurality of indoor units 7A, 7B connected in parallel with each other to the outdoor unit 2. A four-way selector valve 23 is switched to a cooling cycle, a low pressure and a high pressure in the cycle are fixed, a coolant overheating degree of an indoor heat exchanger 71 outlet is fixed to carry out cooling operation in all of the indoor units 7A, 7B, and when an opening of an indoor expansion valve 71 and/or a supercooling expansion valve 28 is a predetermined value or more in this state, it is determined that the coolant charged amount is a gas low state. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a refrigerant filling amount determination method for a multi-air conditioning system that determines whether or not an appropriate amount of refrigerant is sealed in a multi-type air conditioning system, and a refrigerant leakage detection method that detects the presence or absence of refrigerant leakage from the system. Is.

  In the case of a multi-type air conditioning system configured by connecting multiple indoor units in parallel to one outdoor unit, the unit is shipped from the factory with a certain amount of refrigerant sealed in the outdoor unit, and indoors Installation is performed by connecting the unit and the outdoor unit with refrigerant piping. In this case, the length of the refrigerant pipe connecting the indoor unit varies for each multi-air conditioning system, and the model, capacity, and the like of the indoor unit to be connected also vary. For this reason, after installation at the site, the refrigerant pipe length, the type of indoor unit to be connected, the amount of refrigerant commensurate with the capacity, etc. are additionally enclosed.

  As a result, the total amount of refrigerant in the multi-air conditioning system is the amount of refrigerant added at the factory plus the amount of refrigerant additionally enclosed locally, and it is determined whether this is the appropriate amount of refrigerant. The fact is that the technology is not yet well established. For this reason, there are many troubles due to excess or deficiency in the amount of refrigerant, such as failure of air conditioning performance as prescribed, or abnormal operation such as abnormal increase in pressure. In particular, the refrigerant that is additionally encapsulated in the field is a procedure for obtaining the charged amount by calculation based on the refrigerant pipe length between the indoor unit and the outdoor unit and the pipe size, etc., and charging the meter, but this is not protected, or Piping specifications are unclear and accurate calculations cannot be made, which is the main cause of trouble.

  Therefore, on the assumption that the required refrigerant amount during cooling operation is larger than the required refrigerant amount during heating operation, all the usage units are cooled, and the superheat degree control by the usage side expansion valve and the evaporation pressure control by the compressor are performed. A refrigerant amount determination operation mode for detecting the degree of supercooling of the refrigerant at the outlet of the heat source side heat exchanger and determining whether or not the amount of refrigerant charged in the refrigerant circuit is appropriate is proposed. (For example, refer to Patent Document 1).

JP 2006-23072 A

  However, what is described in Patent Document 1 does not consider the influence of the volume of the heat exchanger on the required refrigerant amount. In the multi-air conditioning system, as described above, not only the refrigerant pipe length but also the types and capacities of the connected indoor units vary, so whether the amount of refrigerant required for either cooling or heating is large Depends on the refrigerant pipe length / indoor / outdoor combination. Therefore, there is a face that cannot be determined from the above determination method alone that the refrigerant is always contained in an appropriate amount.

  The present invention has been made in view of such circumstances, so that it is possible to accurately determine a gas low and / or overcharge of the refrigerant filling amount and to enclose an appropriate amount of refrigerant that matches each multi-air conditioning system. An object of the present invention is to provide a refrigerant filling amount determination method and a refrigerant leakage detection method for a multi-air conditioning system.

In order to solve the above-described problems, the refrigerant filling amount determination method and refrigerant leakage detection method of the multi-air conditioning system of the present invention employ the following means.
That is, the refrigerant enclosing amount determination method for a multi-air conditioning system according to the present invention includes a compressor that compresses a refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and outside air, and a refrigerant An outdoor expansion valve for heating, a receiver for storing the refrigerant, a supercooling heat exchanger for imparting supercooling to the refrigerant, and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger And an outdoor unit in which a gas side pipe and a liquid side pipe are led out from the outdoor side refrigerant circuit and heat exchange between the refrigerant and the room air. An indoor heat exchanger and a cooling indoor expansion valve for expanding the refrigerant, between a plurality of sets of indoor side branch gas pipes and indoor side branch liquid pipes branched from the gas side pipe and liquid side pipe, Connect to each other in parallel A plurality of indoor units, and a method for determining the amount of refrigerant enclosed in a multi-air conditioning system, wherein the four-way switching valve is switched to a cooling cycle, and the low pressure and high pressure in the cycle are made constant, All the indoor units are cooled by cooling with the refrigerant superheat degree at the outlet of the indoor heat exchanger being constant, and when the opening degree of the indoor expansion valve and / or the supercooling expansion valve is a predetermined value or more in this state, It is characterized by determining that the refrigerant filling amount is in a gas low state.

In the multi-air conditioning system, when the four-way switching valve is switched to the cooling cycle and all the indoor units are operated, a certain amount of refrigerant is held in all the indoor units, so that the required amount of refrigerant in the cycle is maximized. In the present invention, during the trial operation after the installation of the multi-air conditioning system, the low pressure and high pressure in the cycle are kept constant in this state, and the cooling operation is performed with the refrigerant superheat degree at the outlet of the indoor heat exchanger being constant. And / or when the opening degree of the supercooling expansion valve is equal to or larger than a predetermined value, the refrigerant filling amount is determined to be in the gas low state. That is, by this operation, when an appropriate amount of refrigerant is sealed in the cycle, an appropriate amount of refrigerant is held in each indoor heat exchanger, and the opening degree of each indoor expansion valve is controlled within a predetermined range. Thus, the refrigerant superheat degree at the outlet of the indoor heat exchanger can be controlled to be constant. However, when the refrigerant charging amount is in the gas low state, the refrigerant hold amount in the indoor heat exchanger decreases, and accordingly the opening of the indoor expansion valve gradually increases, eventually becoming fully open and the indoor heat exchanger The refrigerant superheat degree at the outlet cannot be controlled to be constant. In this case, the degree of refrigerant superheat at the outlet of the indoor heat exchanger increases, and the cooling capacity decreases. Accordingly, when even one of the indoor units has an opening of the indoor expansion valve equal to or larger than a predetermined value, it can be determined that the refrigerant is in a gas low state where the amount of refrigerant filled is insufficient, and additional refrigerant is charged to fill the refrigerant. Correct the amount. As a result, it is possible to enclose an appropriate amount of refrigerant that matches each multi-air conditioning system, and to prevent troubles caused by excessive or insufficient refrigerant amounts. In this case, the gas low state can be determined directly from the opening of the indoor expansion valve, but since communication between the indoor unit and the outdoor unit is required, there is a slight time delay in recognizing the gas low.
Similarly, when an appropriate amount of refrigerant is sealed in the supercooling expansion valve, the opening degree is controlled within a predetermined range, and the degree of supercooling of the liquid refrigerant in the liquid side pipe at the outlet of the supercooling heat exchanger Can be controlled to a predetermined value. However, when the refrigerant charging amount is in a gas low state, the gas phase is mixed with the refrigerant in the liquid side pipe, and accordingly the opening degree of the expansion valve for supercooling gradually increases and eventually becomes fully open. It becomes impossible to maintain the degree of supercooling of the liquid refrigerant in the liquid side pipe at a predetermined value. Also in this case, since the amount of refrigerant passing through the indoor expansion valve is reduced, the cooling capacity is lowered. Therefore, even when the opening degree of the supercooling expansion valve is equal to or larger than a predetermined value, it can be determined that the gas low state is established, and the refrigerant filling amount is corrected by additionally filling the refrigerant. As a result, an appropriate amount of refrigerant matching the individual multi-air conditioning system can be sealed, and troubles caused by excessive or insufficient refrigerant amounts can be prevented. In addition, since the expansion valve for supercooling is provided in the outdoor unit, the outdoor unit controller can immediately recognize the gas low state.

  Furthermore, the refrigerant filling amount determination method for the multi-air conditioning system according to the present invention includes a compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, and a refrigerant An outdoor expansion valve for heating, a receiver for storing the refrigerant, a supercooling heat exchanger for imparting supercooling to the refrigerant, and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger And an outdoor unit in which a gas side pipe and a liquid side pipe are led out from the outdoor side refrigerant circuit and heat exchange between the refrigerant and the room air. An indoor heat exchanger and a cooling indoor expansion valve for expanding the refrigerant, between a plurality of sets of indoor side branch gas pipes and indoor side branch liquid pipes branched from the gas side pipe and liquid side pipe, Connected in parallel to each other A plurality of indoor units, and a method for determining the amount of refrigerant enclosed in a multi-air conditioning system, wherein the four-way switching valve is switched to a cooling cycle, and the low pressure and high pressure in the cycle are made constant, One indoor unit is cooled with the refrigerant superheat degree at the outlet of the indoor heat exchanger being constant, and when the refrigerant supercooling degree at the outlet of the outdoor heat exchanger is equal to or higher than a predetermined value in this state, the refrigerant filling amount is over. The charging state is determined.

  In the multi-air conditioning system, when the four-way switching valve is switched to the cooling cycle and one indoor unit is operated, the refrigerant is not held in the other indoor units, so that the required amount of refrigerant in the cycle is minimized. In the present invention, during the trial operation after installing the multi air conditioning system, the low pressure and high pressure in the cycle are kept constant in this state, the cooling operation is performed with the refrigerant superheat degree at the outlet of the indoor heat exchanger being constant, When the refrigerant supercooling degree at the outlet of the container is equal to or greater than a predetermined value, the refrigerant charging amount is determined to be in an overcharged state. That is, in this operation, when an appropriate amount of refrigerant is sealed, the liquid piping from the outdoor heat exchanger to the indoor expansion valve is filled with liquid refrigerant, and an appropriate amount of refrigerant is placed in the outdoor heat exchanger. Since it is held, the refrigerant supercooling degree at the outlet of the outdoor heat exchanger is maintained at a predetermined supercooling degree. However, when the amount of refrigerant charged is overcharged, excess refrigerant accumulates in the outdoor heat exchanger, the degree of refrigerant supercooling at the outlet of the outdoor heat exchanger gradually increases, and eventually the outdoor expansion valve opens. Therefore, the refrigerant supercooling degree at the outlet of the outdoor heat exchanger cannot be maintained at the predetermined supercooling degree. Therefore, when the degree of refrigerant supercooling at the outlet of the outdoor heat exchanger is equal to or greater than a predetermined value, it can be determined that the refrigerant charging amount is in an overcharged state, and the refrigerant is recovered to correct the refrigerant charging amount. As a result, an appropriate amount of refrigerant matching the individual multi-air conditioning system can be sealed, and troubles caused by excessive or insufficient refrigerant amounts can be prevented.

  Furthermore, the refrigerant filling amount determination method for the multi-air conditioning system according to the present invention includes a compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, and a refrigerant An outdoor expansion valve for heating, a receiver for storing the refrigerant, a supercooling heat exchanger for imparting supercooling to the refrigerant, and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger And an outdoor unit in which a gas side pipe and a liquid side pipe are led out from the outdoor side refrigerant circuit and heat exchange between the refrigerant and the room air. An indoor heat exchanger and a cooling indoor expansion valve for expanding the refrigerant, between a plurality of sets of indoor side branch gas pipes and indoor side branch liquid pipes branched from the gas side pipe and liquid side pipe, Connected in parallel to each other A plurality of indoor units, and a method for determining the amount of refrigerant enclosed in a multi-air conditioning system, wherein the four-way switching valve is switched to a heating cycle, and the low pressure and high pressure in the cycle are made constant, One of the indoor units is heated and operated with the refrigerant superheat degree at the outlet of the outdoor heat exchanger being constant, and in this state, the opening degree of the outdoor expansion valve is not less than a predetermined value or the opening degree of the indoor expansion valve is not more than a predetermined value. Sometimes, it is determined that the refrigerant filling amount is in a gas low state.

In the multi-air conditioning system, when the four-way switching valve is switched to the heating cycle and one indoor unit is operated, all the other indoor units are liquid-sealed with the refrigerant. In the present invention, during the trial operation after the installation of the multi-air conditioning system, the low pressure and high pressure in the cycle are kept constant in this state, the heating operation is performed with the refrigerant superheat degree at the outlet of the outdoor heat exchanger being constant, and the outdoor expansion valve When the opening degree is equal to or larger than a predetermined value or the opening degree of the indoor expansion valve is equal to or smaller than the predetermined value, the refrigerant filling amount is determined to be in the gas low state. That is, in this operation, when an appropriate amount of refrigerant is sealed, the appropriate amount of refrigerant is held in the outdoor heat exchanger, and the outdoor expansion valve is controlled within an open range so that the outdoor heat exchange is performed. The degree of refrigerant superheat at the outlet of the vessel can be controlled to be constant. However, when the refrigerant charging amount is in a gas low state, the refrigerant hold amount in the outdoor heat exchanger decreases, the degree of refrigerant superheating at the outlet of the outdoor heat exchanger increases, and accordingly the opening of the outdoor expansion valve increases. It gradually increases and eventually becomes fully open, and the degree of refrigerant superheat at the outlet of the outdoor heat exchanger cannot be controlled to be constant. Therefore, when the degree of opening of the outdoor expansion valve is equal to or greater than a predetermined value, it can be determined that the refrigerant is in a gas low state in which the refrigerant filling amount is insufficient, and the refrigerant filling amount is corrected by additionally charging the refrigerant. As a result, an appropriate amount of refrigerant that matches the individual multi-air conditioning system can be sealed, and troubles due to excessive or insufficient refrigerant amounts can be prevented.
Similarly, when an appropriate amount of refrigerant is sealed, the indoor expansion valve holds a predetermined amount of refrigerant in the indoor heat exchanger, so that the refrigerant subcooling degree at the outlet of the indoor heat exchanger has a predetermined subcooling. Held every time. However, when the refrigerant charging amount is in a gas low state, the refrigerant hold amount in the indoor heat exchanger decreases, the refrigerant subcooling degree at the outlet of the indoor heat exchanger decreases, and accordingly the opening of the indoor expansion valve Gradually becomes smaller and eventually becomes fully closed, and the refrigerant supercooling degree at the outlet of the indoor heat exchanger cannot be controlled to a predetermined supercooling degree. Therefore, when the opening degree of the indoor expansion valve is equal to or less than the predetermined value, it can be determined that the gas low state is insufficient in the refrigerant filling amount, and the refrigerant filling amount is corrected by additionally charging the refrigerant. As a result, an appropriate amount of refrigerant matching the individual multi-air conditioning system can be sealed, and troubles caused by excessive or insufficient refrigerant amounts can be prevented.

  Furthermore, the refrigerant filling amount determination method for the multi-air conditioning system according to the present invention includes a compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, and a refrigerant An outdoor expansion valve for heating, a receiver for storing the refrigerant, a supercooling heat exchanger for imparting supercooling to the refrigerant, and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger And an outdoor unit in which a gas side pipe and a liquid side pipe are led out from the outdoor side refrigerant circuit and heat exchange between the refrigerant and the room air. An indoor heat exchanger and a cooling indoor expansion valve for expanding the refrigerant, between a plurality of sets of indoor side branch gas pipes and indoor side branch liquid pipes branched from the gas side pipe and liquid side pipe, Connected in parallel to each other A plurality of indoor units, and a method for determining the amount of refrigerant enclosed in a multi-air conditioning system, wherein the four-way switching valve is switched to a heating cycle, and the low pressure and high pressure in the cycle are made constant, All the indoor units are heated with the refrigerant superheat degree at the outlet of the outdoor heat exchanger being constant, and when the refrigerant supercooling degree at the outlet of the indoor heat exchanger is equal to or higher than a predetermined value in this state, the refrigerant filling amount is over. The charging state is determined.

  In the multi-air conditioning system, when the four-way switching valve is switched to the heating cycle and all the indoor units are operated, a certain amount of refrigerant is held in all the indoor units, so that the required refrigerant amount for the cycle is minimized. In the present invention, during the trial operation after installing the multi air conditioning system, in this state, the low pressure and high pressure in the cycle are kept constant, the heating operation is performed with the refrigerant superheat degree at the outlet of the outdoor heat exchanger being constant, and the indoor heat exchange When the refrigerant supercooling degree at the outlet of the vessel is greater than or equal to a predetermined value, the refrigerant charging amount is determined to be in an overcharged state. That is, when an appropriate amount of refrigerant is sealed by this operation, the appropriate amount of refrigerant is held in the indoor heat exchanger, so the refrigerant subcooling degree at the outlet of the indoor heat exchanger is set to a predetermined degree of subcooling. Maintained. However, when the refrigerant charge amount is overcharged, excess refrigerant accumulates in the indoor heat exchanger, the degree of refrigerant supercooling at the outlet of the indoor heat exchanger gradually increases, and eventually the opening of the indoor expansion valve Becomes fully open, the refrigerant supercooling degree at the outlet of the indoor heat exchanger cannot be maintained at the predetermined supercooling degree. Accordingly, when the degree of refrigerant supercooling at the outlet of the indoor heat exchanger is equal to or greater than a predetermined value, it can be determined that the refrigerant charging amount is in an overcharged state, and the refrigerant is recovered to correct the refrigerant charging amount. As a result, it is possible to enclose an appropriate amount of refrigerant that matches each multi-air conditioning system, and to prevent troubles caused by excessive or insufficient refrigerant amounts.

  Furthermore, the refrigerant filling amount determination method for the multi-air conditioning system according to the present invention includes a compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, and a refrigerant An outdoor expansion valve for heating, a receiver for storing the refrigerant, a supercooling heat exchanger for imparting supercooling to the refrigerant, and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger And an outdoor unit in which a gas side pipe and a liquid side pipe are led out from the outdoor side refrigerant circuit and heat exchange between the refrigerant and the room air. An indoor heat exchanger and a cooling indoor expansion valve for expanding the refrigerant, between a plurality of sets of indoor side branch gas pipes and indoor side branch liquid pipes branched from the gas side pipe and liquid side pipe, Connected in parallel to each other A refrigerant entrapment amount determination method for a multi-air conditioning system comprising a plurality of indoor units, wherein the gas low determination in the cooling cycle and the overrun in the cooling cycle in the multi-air conditioning system refrigerant entrapment amount determination method described above The charge determination, the gas low determination in the heating cycle, and the overcharge determination in the heating cycle are collectively performed in an appropriate order.

  In a multi-air conditioning system, the refrigerant pipe length, the types of indoor units to be connected, the capacity, etc. vary, so whether the amount of refrigerant required for cooling or heating is large depends on the refrigerant pipe length / room It depends on the combination of external units. In the present invention, the refrigerant filling amount can be checked and corrected by operating in both cooling and heating, and performing gas low determination and overcharge determination in each of them. Refrigerant can be sealed without shortage. Therefore, it is possible to enclose an appropriate amount of refrigerant in consideration of the refrigerant pipe length, model, capacity, number, etc. of the indoor unit connected to the outdoor unit. As a result, troubles caused by excess or deficiency of the refrigerant amount can be solved and the reliability of the product can be improved.

  Furthermore, the refrigerant enclosing amount determination method for a multi-air conditioning system according to the present invention is the same as the refrigerant enclosing amount determination method for the multi-air conditioning system described above, wherein in summer the gas low determination and the overcharge determination are performed in the cooling cycle. In the winter, the gas low determination and the overcharge determination in the heating cycle are performed in preference to the gas low determination and the overcharge determination in the cooling cycle.

  According to the present invention, the gas low determination and overcharge determination in the cooling cycle are preferentially performed in summer, and the gas low determination and overcharge determination in the heating cycle are preferentially performed in winter. The operation in the cooling cycle and the operation in the heating cycle for determining the refrigerant charging amount can be performed by high load operation. For this reason, the compressor can be operated at high Hz, and the refrigerant filling amount can be determined quickly. In particular, when the refrigerant circuit has an accumulator, it is necessary to expel the refrigerant accumulated in the accumulator. However, since the refrigerant can be expelled quickly from the accumulator by the high Hz operation of the compressor, it is possible to determine the amount of refrigerant enclosed. It can be implemented as quickly as possible.

  Furthermore, the refrigerant leakage detection method for a multi-air conditioning system according to the present invention determines the refrigerant charging amount by the above-described refrigerant charging amount determination method during trial operation after installation of the multi-air conditioning system, and stores the result as initial operation data. Then, it is characterized by detecting the presence or absence of refrigerant leakage by performing the same refrigerant filling amount determination at an appropriate time thereafter and comparing the operation data with the initial operation data.

  According to the present invention, during the trial operation after installation of the multi-air conditioning system, the refrigerant filling amount is determined, the result is stored as initial operation data, and the same refrigerant filling amount determination is performed at an appropriate time thereafter, and the operation is performed. By comparing the data with the initial operation data, it is possible to easily detect the presence or absence of refrigerant leakage. Therefore, if the refrigerant is leaked, necessary measures can be taken promptly, which can lead to trouble prevention and environmental protection due to gas low.

According to the method for determining the amount of refrigerant enclosed in the multi-air conditioning system according to the present invention, the amount of refrigerant enclosed can be easily and appropriately determined by a method that matches the individual multi-air conditioning system. This can be prevented beforehand. In particular, the amount of refrigerant can be determined in consideration of the volume of the heat exchanger, the length of the refrigerant pipe, the model of the connected indoor unit, the capacity, etc., and as a result, an appropriate amount of refrigerant can be sealed. .
Further, according to the refrigerant leakage detection method of the multi-air conditioning system according to the present invention, the initial operation data of the refrigerant charging amount determination acquired during the trial operation, and the operation data acquired by performing the similar refrigerant charging amount determination at an appropriate time thereafter, By comparing the above, it is possible to easily detect the presence or absence of refrigerant leakage, which can lead to trouble prevention and environmental protection due to gas low.

Embodiments according to the present invention will be described below with reference to the drawings.
[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.
(Configuration of multi air conditioning system)
FIG. 1 shows a cooling cycle diagram of the multi-air conditioning system 1 according to the present embodiment.
The multi air conditioning system 1 includes one outdoor unit 2, a gas side pipe 4 and a liquid side pipe 5 led out from the outdoor unit 2, and a branching device 6 between the gas side pipe 4 and the liquid side pipe 5. And a plurality of indoor units 7A and 7B connected in parallel.

  The outdoor unit 2 exchanges heat between the inverter-driven compressor 21 that compresses the refrigerant, the oil separator 22 that separates the lubricating oil from the refrigerant gas, the four-way switching valve 23 that switches the circulation direction of the refrigerant, and the refrigerant and the outside air. An outdoor heat exchanger 24 for heating, an outdoor electronic expansion valve (EEVH) 25 for heating, a receiver 26 for storing liquid refrigerant, a supercooling heat exchanger 27 for imparting supercooling to the liquid refrigerant during cooling, and supercooling A supercooling electronic expansion valve (EEVSC) 28 that controls the amount of refrigerant that is diverted to the heat exchanger 27, an accumulator 29 that separates liquid from refrigerant gas sucked into the compressor 21, and a gas side operation valve 30. And a liquid side operation valve 31, as known in the art, such as a discharge pipe 32A, a gas pipe 32B, a liquid pipe 32C, a gas pipe 32D, a suction pipe 32E, and a supercooling Pibus pipe 32F. Are connected via a medium pipe, constitute the outdoor refrigerant circuit 33. The outdoor unit 2 is provided with an outdoor fan 34 that blows outside air to the outdoor heat exchanger 24. Note that a predetermined amount of refrigerant is normally enclosed in the refrigerant circuit 33 of the outdoor unit 2 and is shipped from the factory in that state.

  The gas side pipe 4 and the liquid side pipe 5 are refrigerant pipes connected to the gas side operation valve 30 and the liquid side operation valve 31 of the outdoor unit 2, and are connected to the outdoor unit 2 and to it during installation on site. The length is appropriately determined depending on the distance between the indoor units 7A and 7B. An appropriate number of branching devices 6 are provided in the middle of the gas side piping 4 and the liquid side piping 5, and an appropriate number of indoor units 7 </ b> A and 7 </ b> B are connected via the branching devices 6.

  The indoor units 7A and 7B exchange indoor air through an indoor heat exchanger 71 that exchanges heat between the refrigerant and room air for indoor air conditioning, an indoor electronic expansion valve (EEVC) 72 for cooling, and the indoor heat exchanger 71. An indoor fan 73 to be circulated, and is connected to the branching device 6 through the indoor branch gas pipe 4A and the indoor branch liquid pipe 5A. In the present embodiment, an example in which two indoor units 7A and 7B are connected is shown, but the number of connected indoor units may be three or more.

  The multi air conditioning system 1 includes an outdoor unit 2, indoor units 7A and 7B, a gas side pipe 4, a liquid side pipe 5, branch gas pipes 4A and 4B, branch liquid pipes 5A and 5B, branch pipes 6 and the like. Are separately carried into the installation site, and the outdoor unit 2 and the indoor units 7A and 7B are connected and constructed through the refrigerant pipe at the site. In general, the outdoor unit 2 is installed on the rooftop or outside the building, and the indoor units 7A and 7B are arranged in each air conditioning zone or each room. For this reason, the pipe lengths of the gas side pipe 4, the liquid side pipe 5, the branch gas pipes 4A and 4B, the branch liquid pipes 5A and 5B, etc., connecting the outdoor unit 2 and the indoor units 7A and 7B vary greatly depending on the installation environment. . Also, indoor units 7A and 7B are often connected in a mixture of indoor units of different types (models) and capacities. For these reasons, after installing the multi-air conditioning system 1, the refrigerant pipe length, the indoor unit type (model), and the amount of refrigerant corresponding to the difference in capacity are additionally charged locally, and an appropriate amount of refrigerant is enclosed in the system. To be.

(Cooling cycle operation)
In the multi air conditioning system 1 described above, the cooling cycle operation is performed as follows.
In the cooling cycle operation, the refrigerant is circulated in the direction of the solid line arrow shown in FIG. Further, FIG. 3 shows a Mollier diagram during the cooling cycle operation, and points A to F on the Mollier diagram correspond to positions A to F on the refrigerant circuit shown in FIG.
The high-temperature and high-pressure refrigerant gas compressed by the compressor 21 is discharged to the discharge pipe 32A, and after the lubricating oil contained in the refrigerant is separated by the oil separator 22, it is circulated to the gas pipe 32B side by the four-way switching valve 23. The outdoor heat exchanger 24 exchanges heat with the outside air blown by the outdoor fan 34 to be condensed and liquefied. This liquid refrigerant passes through the outdoor electronic expansion valve 25 via the liquid pipe 32C, is temporarily stored in the receiver 26, and the circulation amount is adjusted. The liquid refrigerant that has passed through the receiver 26 is partially passed through the bypass pipe 32F in the process of passing through the supercooling heat exchanger 27, is heat-exchanged with the refrigerant adiabatically expanded by the supercooling electronic expansion valve 28, is cooled, and is cooled. After the subcooling degree is given (from the point B to the point C on the Mollier diagram shown in FIG. It is led out to the pipe 5. The liquid refrigerant led out to the liquid side pipe 5 is diverted to the branch liquid pipes 5A and 5B of the indoor units 7A and 7B by the branching unit 6.

  The liquid refrigerant divided into the branch liquid pipes 5A and 5B flows into the indoor units 7A and 7B, is adiabatically expanded by the indoor electronic expansion valve 72 for cooling, and becomes a gas-liquid two-phase flow. Is flowed into. In the indoor heat exchanger 71, the indoor air circulated by the indoor fan 73 and the refrigerant are heat-exchanged, and the indoor air is cooled and provided for indoor cooling. On the other hand, the refrigerant is vaporized and reaches the branching device 6 through the branch gas pipes 4A and 4B, and is merged with the refrigerant gas from the other indoor units in the gas side pipe 4. The refrigerant gas merged in the gas side pipe 4 returns to the outdoor unit 2 again, reaches the suction pipe 32E through the gas side operation valve 30, the gas pipe 32D, and the four-way switching valve 23, and merges with the refrigerant gas from the bypass pipe 32F. Is introduced into the accumulator 29. The accumulator 29 separates the liquid component contained in the refrigerant gas, sucks only the gas component into the compressor 21, and the refrigerant is compressed again in the compressor 21. The cooling operation is performed by repeating the above cycle.

(Gas low judgment in the cooling cycle)
The gas low determination in the cooling cycle is performed in order to determine whether or not an appropriate amount of refrigerant is sealed in the refrigeration cycle of the multi air conditioning system 1 after the multi air conditioning system 1 is installed.
In order to determine the gas low, the four-way switching valve 23 is switched to the cooling cycle, and all the indoor units 7A and 7B are operated in the cooling cycle. When all the indoor units 7A and 7B are operated, as shown in FIG. 1, a certain amount of refrigerant is held in the indoor units 7A and 7B. This is because the required amount of refrigerant is the largest in the cooling cycle, and the gas low determination is performed in this state.

In the operation state of all the indoor units 7A and 7B, the low pressure and high pressure in the cooling cycle are controlled to be constant, and the refrigerant superheat degree (SH) at the outlet of the indoor heat exchanger 71 is controlled to be constant. Stabilize. The low pressure pressure stabilization control is performed by, for example, the capacity control (rotational speed control) of the compressor 21, and the high pressure pressure constant control is performed by, for example, the rotational speed control of the outdoor fan 34. The control of the refrigerant superheat degree at the outlet 71 can be controlled by the opening degree control of the indoor electronic expansion valve (EEVC) 72.
When the opening degree of the indoor electronic expansion valve (EEVC) 72 and / or the supercooling electronic expansion valve (EEVSC) 28 is equal to or greater than a predetermined value (fully opened) in this state of transfer, the refrigerant filling amount is in the gas low state. judge.

  That is, when an appropriate amount of refrigerant is sealed in the multi-air conditioning system 1 by the above operation, an appropriate amount of refrigerant is held in each indoor heat exchanger 71 as shown in FIG. The opening degree of the expansion valve 72 is controlled within a predetermined range, and the degree of refrigerant superheat at the outlet of the indoor heat exchanger 71, that is, the F position on the refrigerant circuit shown in FIG. 1 (the F point on the Mollier diagram of FIG. 3). (SH) can be controlled to be constant. However, when the refrigerant charging amount is in the gas low state, the refrigerant hold amount in the indoor heat exchanger 71 decreases, and accordingly, the opening degree of the indoor electronic expansion valve 72 keeps the above refrigerant superheat degree (SH) constant. Therefore, it gradually increases and eventually becomes fully open, and the refrigerant superheat degree at the outlet of the indoor heat exchanger 71 cannot be controlled to be constant. In this case, the refrigerant superheat degree (SH) at the outlet of the indoor heat exchanger 71 is increased, and the cooling capacity is reduced.

As described above, the opening degree of the indoor electronic expansion valve 72 of all the indoor units 7A and 7B is equal to or greater than the predetermined value when the refrigerant filling amount is insufficient and the gas low state is established. Judgment can be made. Therefore, in this case, the refrigerant filling amount can be corrected by additionally filling the refrigerant. As a result, an appropriate amount of refrigerant matching the individual multi-air conditioning system 1 can be sealed, and troubles due to excessive or insufficient refrigerant amounts can be prevented in advance.
In this case, the gas low state can be determined directly from the opening degree of the indoor electronic expansion valve 72, but it is necessary to confirm it on the outdoor unit 2 side by communication between the indoor units 7A and 7B and the outdoor unit 2. Therefore, there will be a slight time delay in the recognition of gas low.

  Similarly to the above, when an appropriate amount of refrigerant is sealed in the multi-air conditioning system 1, the degree of opening of the supercooling electronic expansion valve 28 is controlled within a predetermined range, and the supercooling heat exchanger The supercooling degree of the liquid refrigerant at the liquid outlet pipe 32C at the 27 outlet, that is, the C position on the refrigerant circuit shown in FIG. 1 (C point on the Mollier diagram of FIG. 3) can be controlled to a predetermined value. However, when the refrigerant charging amount is in the gas low state, the gas phase is mixed with the refrigerant in the liquid side pipe 32C, and the supercooling degree is controlled to a predetermined value accordingly. The opening gradually increases and eventually becomes fully open, and it becomes impossible to maintain the subcooling degree of the liquid refrigerant at the liquid side pipe 32C, that is, the position C on the refrigerant circuit shown in FIG. In this case as well, the amount of refrigerant passing through the indoor electronic expansion valve 72 is reduced, so that the cooling capacity is reduced.

Therefore, as described above, even when the opening degree of the supercooling electronic expansion valve 28 is equal to or larger than the predetermined value, it can be determined that the gas low state is established, and the refrigerant charging amount can be corrected by additionally charging the refrigerant. it can. As a result, an appropriate amount of refrigerant matching the individual multi-air conditioning system 1 can be sealed, and troubles due to excessive or insufficient refrigerant amounts can be prevented in advance.
In addition, since the electronic expansion valve 28 for supercooling is provided in the outdoor unit 2, the gas low state can be immediately recognized by the controller on the outdoor unit 2 side.

(Overcharge judgment in cooling cycle)
Overcharge determination in the cooling cycle is performed in order to determine whether or not an appropriate amount of refrigerant is sealed in the refrigeration cycle of the multi air conditioning system 1 after the multi air conditioning system 1 is installed, as in the above-described gas low determination. To be done.
In order to determine overcharge, the four-way switching valve 23 is switched to the cooling cycle, and only one indoor unit 7A, 7B is cooled in the cooling cycle. This is because when only one indoor unit 7A, 7B is cooled, as shown in FIG. 2, a certain amount of refrigerant is held in the operated indoor unit 7A. However, since the indoor electronic expansion valve 72 is fully closed, the other indoor units 7B are not supplied with refrigerant and are in an empty state. This is because the required refrigerant amount is the smallest in the cooling cycle, and the overcharge determination is performed in this state.

In the single unit operating state of this indoor unit 7A, the low pressure and high pressure in the cooling cycle are controlled to be constant, and the refrigerant superheat degree (SH) at the outlet of the indoor heat exchanger 71 is controlled to be stable. Let The low pressure pressure, the high pressure pressure, and the refrigerant superheat degree (SH) are controlled in the same manner as in the case of the gas low determination described above, the capacity control (rotational speed control) of the compressor 21, the rotational speed control of the outdoor fan 34, It can be controlled by opening degree control of the electronic expansion valve (EEVC) 72.
In this operation state, when the refrigerant supercooling degree (SC) at the outlet of the outdoor heat exchanger 71 is equal to or greater than a predetermined value, it is determined that the refrigerant charging amount is in the overcharge state.

  That is, when an appropriate amount of refrigerant is sealed by the above operation, the liquid pipe 32C, the liquid side pipe 5, and the chamber from the outdoor heat exchanger 24 to the indoor electronic expansion valve (EEVC) 72 Since the inner branch liquid pipe 5A is filled with liquid refrigerant and an appropriate amount of refrigerant is held in the outdoor heat exchanger 24, the outlet of the outdoor heat exchanger 24, that is, the refrigerant circuit shown in FIG. The refrigerant supercooling degree (SC) at the upper B position (point B on the Mollier diagram of FIG. 3) is maintained at a predetermined supercooling degree. However, when the amount of refrigerant enclosed is overcharged, excess refrigerant accumulates in the outdoor heat exchanger 24, and the degree of refrigerant supercooling at the outlet of the outdoor heat exchanger 24 gradually increases, and eventually the outdoor electronic expansion occurs. Since the opening degree of the valve (EEVH) 25 is fully opened, the refrigerant supercooling degree (SC) at the outlet of the outdoor heat exchanger 24 cannot be maintained at a predetermined supercooling degree.

  As described above, the refrigerant supercooling degree at the outlet of the outdoor heat exchanger 24 becomes equal to or greater than a predetermined value when the refrigerant charging amount is excessive and it can be determined that the refrigerant is in an overcharged state. In this case, the refrigerant can be recovered to correct the refrigerant filling amount. As a result, an appropriate amount of refrigerant matching the individual multi-air conditioning system can be sealed, and troubles due to excessive or insufficient refrigerant amounts can be prevented.

(Heating cycle operation)
In the multi air conditioning system 1 described above, the heating cycle operation is performed as follows.
During the heating cycle operation, the refrigerant is circulated in the direction of the solid line arrow shown in FIG. FIG. 6 shows a Mollier diagram at the time of heating cycle operation, and a to e on the Mollier diagram correspond to positions a to e on the refrigerant circuit shown in FIG.
The high-temperature and high-pressure refrigerant gas compressed by the compressor 21 is discharged to the discharge pipe 32A, and after the lubricating oil contained in the refrigerant is separated by the oil separator 22, it is circulated to the gas pipe 32D side by the four-way switching valve 23. The This refrigerant is led out from the outdoor unit 2 through the gas side operation valve 30 and the gas side pipe 4, and is further introduced into the indoor units 7A and 7B through the branch unit 6 and the indoor side branch gas pipes 4A and 4B. The high-temperature and high-pressure refrigerant gas introduced into the indoor units 7A and 7B is heat-exchanged with the indoor air circulated by the indoor fan 73 in the indoor heat exchanger 71, and the indoor air is heated and used for indoor heating. On the other hand, the condensed and liquefied liquid refrigerant passes through the indoor electronic expansion valve (EEVC) 72, reaches the branching device 6 through the indoor side branch liquid pipes 5A and 5B, and is joined here. After that, it returns to the outdoor unit 2.

  The refrigerant that has returned to the outdoor unit 2 passes through the liquid side operation valve 31 and the supercooling heat exchanger 27, reaches the receiver 26, is temporarily stored in the receiver 26, and the circulation amount is adjusted. This liquid refrigerant is adiabatically expanded by the outdoor electronic expansion valve (EEVH) 25 for heating through the liquid pipe 32C, and flows into the outdoor heat exchanger 24 as a gas-liquid two-phase refrigerant. In the outdoor heat exchanger 24, heat is exchanged between the outside air blown by the outdoor fan 34 and the refrigerant, and the refrigerant absorbs heat from the outside air and is evaporated and gasified. This refrigerant is introduced from the outdoor heat exchanger 24 into the accumulator 29 through the gas pipe 32B, the four-way switching valve 23, and the suction pipe 32E. In the accumulator 29, the liquid component contained in the refrigerant gas is separated and only the gas component is sucked into the compressor 21, and the refrigerant is compressed again by the compressor 21. A heating operation is performed by repeating the above cycle.

(Gas low judgment in heating cycle)
As for the gas low determination in the heating cycle, is the appropriate amount of refrigerant sealed in the refrigeration cycle of the multi air conditioning system 1 after the multi air conditioning system 1 is installed, as in the gas low and overcharge determination in the cooling cycle described above? This is done to determine whether or not.
In order to determine the gas low, the four-way switching valve 23 is switched to the heating cycle, and only one indoor unit 7A, 7B is operated in the heating cycle. As a result, as shown in FIG. 4, a certain amount of refrigerant is held in the indoor unit 7A to be operated, and in all the other indoor units 7B, the indoor expansion valve 72 is fully closed (slightly opened). It will be in the state sealed with the liquid refrigerant. This is because the required amount of refrigerant is the largest in the heating cycle, and the gas low determination is performed in this state.

In the single unit operation state of the indoor unit 7A, the low pressure and high pressure in the heating cycle are controlled to be constant, and the refrigerant superheat degree (SH) at the outlet of the outdoor heat exchanger 24 is controlled to be stable. Let The low pressure pressure stabilization control is performed by, for example, the rotational speed control of the outdoor fan 35, and the high pressure pressure stabilization control is performed by, for example, the capacity control (rotational speed control) of the compressor 21. The refrigerant superheat degree control of the 24 outlets can be controlled by, for example, opening degree control of the outdoor electronic expansion valve (EEVH) 25.
And in this driving | running state, when the opening degree of the outdoor electronic expansion valve (EEVH) 25 is more than a predetermined value, or the opening degree of the indoor electronic expansion valve 72 is less than a predetermined value, it can determine with refrigerant | coolant enclosure amount being a gas low state. .

  That is, when an appropriate amount of refrigerant is sealed by the above operation, an appropriate amount of refrigerant is held in the outdoor heat exchanger 24, and the outdoor electronic expansion valve (EEVH) 25 has an opening within a predetermined range. The refrigerant superheat degree (SH) at the outlet of the outdoor heat exchanger 24, that is, the e position on the refrigerant circuit shown in FIG. 4 (point e on the Mollier diagram shown in FIG. 6) is controlled to be constant. Can do. However, when the refrigerant charging amount is in a gas low state, the refrigerant hold amount in the outdoor heat exchanger 24 decreases, and the refrigerant superheat degree (SH) at the outlet of the outdoor heat exchanger 24 increases, and accordingly, the outdoor electron The opening degree of the expansion valve (EEVH) 25 gradually increases, eventually becomes fully open, and the refrigerant superheat degree (SH) at the outlet of the outdoor heat exchanger 24 (the above-mentioned e position and e point) cannot be controlled to be constant. .

  As described above, the opening degree of the outdoor electronic expansion valve 25 is equal to or larger than a predetermined value when the refrigerant filling amount is insufficient and it can be determined that the gas low state is set. In this case, it is possible to correct the amount of refrigerant filled by additionally filling the refrigerant. As a result, an appropriate amount of refrigerant matching the individual multi-air conditioning system can be sealed, and troubles due to excessive or insufficient refrigerant amounts can be prevented.

  Similarly to the above, since the indoor electronic expansion valve (EEVC) 72 holds a predetermined amount of refrigerant in the indoor heat exchanger 71 when an appropriate amount of refrigerant is sealed, the indoor heat exchanger 71. 4, that is, the refrigerant supercooling degree (SC) at the position b on the refrigerant circuit shown in FIG. 4 (point b on the Mollier diagram shown in FIG. 6) is maintained at a predetermined supercooling degree. However, when the refrigerant charging amount is in a gas low state, the refrigerant hold amount in the indoor heat exchanger 71 decreases, and the refrigerant subcooling degree (SC) at the outlet of the indoor heat exchanger 71 (b position and b point above). ) Becomes smaller, and accordingly, the opening degree of the indoor electronic expansion valve (EEVC) 72 gradually becomes smaller, eventually becomes fully closed, and the degree of refrigerant supercooling at the outlet of the indoor heat exchanger 71 (the above b position and b point) (SC) cannot be controlled to a predetermined degree of supercooling. Therefore, even when the opening degree of the indoor electronic expansion valve (EEVC) 72 is equal to or smaller than the predetermined value, it can be determined that the gas low state is insufficient in the refrigerant filling amount. In this case, it is possible to correct the amount of refrigerant filled by additionally filling the refrigerant. As a result, it is possible to enclose an appropriate amount of refrigerant that matches each multi-air conditioning system, and to prevent troubles caused by excessive or insufficient refrigerant amounts.

(Overcharge judgment in heating cycle)
Whether the overcharge determination in the heating cycle is the same as the gas low determination in the heating cycle described above, whether or not an appropriate amount of refrigerant is sealed in the refrigeration cycle of the multi air conditioning system 1 after the multi air conditioning system 1 is installed. Done to judge.
In order to determine overcharge, the four-way switching valve 23 is switched to the heating cycle, and all the indoor units 7A and 7B are operated in the heating cycle. If it carries out like this, as shown in FIG. 5, a fixed quantity of refrigerant | coolant will be hold | maintained at indoor unit 7A, 7B, respectively. This is because the required refrigerant amount is the smallest in the heating cycle, and the gas low determination is performed in this state.

In the operation state of all the indoor units 7A and 7B, the low pressure and high pressure in the heating cycle are controlled to be constant, and the refrigerant superheat degree (SH) at the outlet of the outdoor heat exchanger 24 is controlled to be constant. Stabilize. The constant control of the low pressure, the high pressure, and the superheat degree of the refrigerant is performed in the same manner as in the above-described gas-low determination. It can be controlled by opening degree control of (EEVH) 25.
In this operating state, when the refrigerant supercooling degree (SC) at the outlet of the indoor heat exchanger 71 is equal to or greater than a predetermined value, the refrigerant charging amount can be determined to be an overcharged state.

  That is, when an appropriate amount of refrigerant is sealed by this operation, the appropriate amount of refrigerant is held in the indoor heat exchanger 71, so the outlet of the indoor heat exchanger 71, that is, the refrigerant shown in FIG. The refrigerant supercooling degree (SC) at the position b on the circuit (point b on the Mollier diagram shown in FIG. 6) is maintained at a predetermined degree of supercooling. However, when the refrigerant charging amount is in an overcharged state, excess refrigerant accumulates in the indoor heat exchanger 71, and the refrigerant supercooling degree at the outlet of the indoor heat exchanger 71 (the above b position and b point) ( SC) gradually increases, and eventually, the opening degree of the indoor electronic expansion valve (EEVC) 72 is fully opened, and the refrigerant supercooling degree (SC) at the outlet of the indoor heat exchanger 71 (the above b position and b point) Cannot be maintained at a predetermined degree of supercooling.

  As described above, the refrigerant supercooling degree (SC) at the outlet of the indoor heat exchanger 71 is equal to or higher than a predetermined value when the refrigerant charging amount is excessive and it can be determined that the refrigerant is in an overcharged state. In this case, the refrigerant can be recovered to correct the refrigerant filling amount. As a result, an appropriate amount of refrigerant matching the individual multi-air conditioning system 1 can be sealed, and troubles due to excessive or insufficient refrigerant amounts can be prevented.

  As described above, according to the present embodiment, it is possible to accurately determine whether the gas is low or overcharge in each of the cooling cycle operation and the heating cycle operation. Based on this determination, it is possible to enclose an appropriate amount of refrigerant in each of the multi-air conditioning systems 1 having different refrigerant pipe lengths, connected indoor unit models, capacities, and the like. Therefore, it is possible to prevent troubles caused by excess or deficiency of the refrigerant amount and improve the reliability of the product.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.
In the first embodiment, the case where the gas low determination in the cooling cycle, the overcharge determination in the cooling cycle, the gas low determination in the heating cycle, and the overcharge determination in the heating cycle are individually performed has been described. On the other hand, in the present embodiment, these four determinations are collectively executed in an appropriate order or in a specific order.

  The first method includes the above-described four determinations, that is, the gas low determination in the cooling cycle, the overcharge determination in the cooling cycle, the gas low determination in the heating cycle, and the overcharge determination in the heating cycle. By a similar method, the processes are executed collectively in an appropriate order, and whether or not the refrigerant charging amount is gas low or overcharge is determined based on the result. In the multi-air-conditioning system 1, the refrigerant pipe length, the types of indoor units 7A and 7B to be connected, the capacity, and the like are as described above. The amount of refrigerant required for either cooling or heating is as described above. Whether it becomes large or not depends on the combination of refrigerant pipe length / indoor / outdoor unit. In the present embodiment, the operation is performed in both the cooling cycle and the heating cycle, and the gas low determination and the overcharge determination are performed in each of them to determine whether or not the gas is low or overcharged.

As described above, by checking the suitability of the refrigerant filling amount by four determinations, it is possible to accurately determine the suitability of the refrigerant filling amount regardless of whether the required refrigerant amount is large for cooling or heating. In case of overcharge, it can be corrected. For this reason, a refrigerant | coolant can be enclosed with respect to each multi air-conditioning system 1 without each excess and deficiency.
Therefore, it is possible to enclose an appropriate amount of refrigerant in consideration of the refrigerant pipe length, model, capacity, number, etc. of the indoor units 7A and 7B connected to the outdoor unit 2. As a result, troubles caused by excessive or insufficient refrigerant amounts can be solved, and the reliability of the product can be improved.
In addition, the method of performing the above four determinations in a batch as appropriate without deciding the order is effective in intermediate periods such as spring and autumn.

  In the second method, the above four determinations are executed in a specific order. That is, in summer, the gas low determination and overcharge determination in the cooling cycle are performed in preference to the gas low determination and overcharge determination in the heating cycle described above, and in the winter, the gas low determination in the heating cycle described above are performed. In addition, the overcharge determination is performed in preference to the gas low determination and the overcharge determination in the above-described cooling cycle.

In this way, in the summer season, priority is given to the gas low determination and overcharge determination in the cooling cycle, and in the winter season, priority is given to the gas low determination and overcharge determination in the heating cycle, thereby determining the refrigerant filling amount. The operation in the cooling cycle and the operation in the heating cycle can be respectively performed at a high load. This high load operation causes the compressor 21 to operate at a high Hz and the refrigerant circulation amount is increased, so that the refrigerant filling amount can be quickly determined. In particular, when the refrigerant circuit has the accumulator 29, it is necessary to expel the refrigerant accumulated in the accumulator 29. However, the refrigerant can be quickly expelled from the accumulator 29 by the high-frequency operation of the compressor 21, and the amount of refrigerant enclosed can be determined. Can be carried out quickly.
Therefore, the time required for determining the refrigerant charging amount can be shortened as much as possible, and the working efficiency can be improved.

[Third Embodiment]
Next, a third embodiment of the present invention will be described.
While the first embodiment and the second embodiment relate to the refrigerant filling amount determination method for determining whether the refrigerant filling amount of the multi-air conditioning system 1 is gas low or overcharge, The embodiment is different in that the leakage of the refrigerant is detected using the refrigerant filling amount determination method.
The refrigerant sealed in the refrigeration cycle of the multi-air conditioning system 1 may leak for some reason during use. In this case, not only the specified air conditioning performance cannot be obtained, but also the environment is affected. Therefore, it is very useful to be able to easily detect the leakage of the refrigerant sealed in the refrigeration cycle.

  The above-described refrigerant filling amount determination method of the multi-air conditioning system is executed during a trial operation after installation of the multi-air conditioning system 1 to determine whether the refrigerant filling amount is appropriate. In the present embodiment, refrigerant leakage is detected by using the determination result of the refrigerant filling amount. That is, the suitability determination result of the refrigerant filling amount at the time of trial operation after installation of the multi air conditioning system 1 is stored in the storage unit of the controller as initial operation data. Then, the same refrigerant filling amount determination is performed at an appropriate time thereafter, for example, at the time of periodic inspection, etc., and similar operation data is acquired and compared with the initial operation data acquired during the trial operation stored in the storage unit. Thus, it is possible to detect the presence or absence of refrigerant leakage.

  In this way, during the trial operation after installing the multi air conditioning system, the suitability of the refrigerant filling amount is determined, the result is stored as initial operation data, the similar refrigerant filling amount determination is performed at an appropriate time thereafter, and the operation data is stored. By comparing with the initial operation data, it is possible to easily detect the presence or absence of refrigerant leakage. For this reason, if a refrigerant leak is detected, it is possible to take necessary measures promptly, leading to trouble prevention and environmental protection due to gas low.

  In the above-described embodiment, the overcharge determination in the cooling cycle is performed by operating only one indoor unit 7A, 7B, but is performed by operating all the indoor units 7A, 7B. Also good. In this case, it is necessary to set the threshold value of the refrigerant supercooling degree at the outlet of the outdoor heat exchanger 71 for determining whether or not it is overcharged to a value different from that in the case of single-unit operation.

It is a driving | running state figure at the time of the gas low determination in the cooling cycle of the refrigerant | coolant enclosure amount determination method of the multi air conditioning system which concerns on 1st Embodiment of this invention. It is a driving | running state figure at the time of the overcharge determination in the cooling cycle of the refrigerant | coolant enclosure amount determination method of the multi air conditioning system which concerns on 1st Embodiment of this invention. It is a Mollier diagram in a cooling cycle of a refrigerant enclosure amount judging method of a multi air-conditioning system concerning a 1st embodiment of the present invention. It is a driving | running state figure at the time of the gas low determination in the heating cycle of the refrigerant | coolant enclosure amount determination method of the multi air conditioning system which concerns on 1st Embodiment of this invention. It is a driving | running state figure at the time of the overcharge determination in the heating cycle of the refrigerant | coolant enclosure amount determination method of the multi air conditioning system which concerns on 1st Embodiment of this invention. It is a Mollier diagram in the heating cycle of the refrigerant | coolant enclosure amount determination method of the multi air conditioning system which concerns on 1st Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multi air-conditioning system 2 Outdoor unit 4 Gas side piping 4A, 4B Indoor side branch gas piping 5 Liquid side piping 5A, 5B Indoor side branch liquid piping 7A, 7B Indoor unit 21 Compressor 23 Four-way switching valve 24 Outdoor heat exchanger 25 Outdoor Electronic expansion valve (EEVH)
26 Receiver 27 Supercooling heat exchanger 28 Supercooling electronic expansion valve (EEVSC)
32A, 32B, 32C, 32D, 32E, 32F Refrigerant piping 33 Outdoor refrigerant circuit 71 Indoor heat exchanger 72 Indoor electronic expansion valve (EEVC)

Claims (7)

A compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, an outdoor expansion valve for heating that expands the refrigerant, and a receiver that stores the refrigerant An outdoor refrigerant circuit configured by sequentially connecting a supercooling heat exchanger for imparting supercooling to the refrigerant and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger by refrigerant piping An outdoor unit from which the gas side pipe and the liquid side pipe are led out from the outdoor refrigerant circuit,
A plurality of sets of indoor side branch gas pipes that are provided with an indoor heat exchanger that exchanges heat between the refrigerant and room air and an indoor expansion valve for cooling that expands the refrigerant, and are branched from the gas side pipe and the liquid side pipe And a plurality of indoor units connected in parallel with each other between the indoor branch liquid pipes, and a refrigerant sealing amount determination method for a multi air conditioning system,
The four-way switching valve is switched to a cooling cycle, the low pressure and high pressure in the cycle are made constant, and the indoor units are all cooled with the refrigerant superheat degree at the outlet of the indoor heat exchanger being made constant,
In this state, when the opening degree of the indoor expansion valve and / or the subcooling expansion valve is equal to or greater than a predetermined value, the refrigerant filling amount is determined to be in the gas low state, and the refrigerant filling amount determining method for the multi-air conditioning system is characterized. . A compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, an outdoor expansion valve for heating that expands the refrigerant, and a receiver that stores the refrigerant An outdoor refrigerant circuit configured by sequentially connecting a supercooling heat exchanger for imparting supercooling to the refrigerant and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger by refrigerant piping An outdoor unit from which the gas side pipe and the liquid side pipe are led out from the outdoor refrigerant circuit,
A plurality of sets of indoor side branch gas pipes that are provided with an indoor heat exchanger that exchanges heat between the refrigerant and room air and an indoor expansion valve for cooling that expands the refrigerant, and are branched from the gas side pipe and the liquid side pipe And a plurality of indoor units connected in parallel with each other between the indoor branch liquid pipes, and a refrigerant sealing amount determination method for a multi air conditioning system,
The four-way switching valve is switched to a cooling cycle, and the low pressure and high pressure in the cycle are made constant, and the cooling of the indoor unit is performed by cooling one indoor unit with a constant refrigerant superheat degree at the outlet of the indoor heat exchanger,
In this state, when the refrigerant supercooling degree at the outlet of the outdoor heat exchanger is equal to or greater than a predetermined value, the refrigerant filling amount is determined to be an overcharged state. A compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, an outdoor expansion valve for heating that expands the refrigerant, and a receiver that stores the refrigerant An outdoor refrigerant circuit configured by sequentially connecting a supercooling heat exchanger for imparting supercooling to the refrigerant and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger by refrigerant piping An outdoor unit from which the gas side pipe and the liquid side pipe are led out from the outdoor refrigerant circuit,
A plurality of sets of indoor side branch gas pipes that are provided with an indoor heat exchanger that exchanges heat between the refrigerant and room air and an indoor expansion valve for cooling that expands the refrigerant, and are branched from the gas side pipe and the liquid side pipe And a plurality of indoor units connected in parallel with each other between the indoor branch liquid pipes, and a refrigerant sealing amount determination method for a multi air conditioning system,
The four-way switching valve is switched to a heating cycle, the low pressure and high pressure in the cycle are made constant, and one indoor unit is heated and operated with a constant refrigerant superheat degree at the outlet of the outdoor heat exchanger,
In this state, when the opening degree of the outdoor expansion valve is equal to or greater than a predetermined value or when the opening degree of the indoor expansion valve is equal to or less than a predetermined value, it is determined that the refrigerant charging amount is a gas low state. Quantity judgment method. A compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, an outdoor expansion valve for heating that expands the refrigerant, and a receiver that stores the refrigerant An outdoor refrigerant circuit configured by sequentially connecting a supercooling heat exchanger for imparting supercooling to the refrigerant and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger by refrigerant piping An outdoor unit from which the gas side pipe and the liquid side pipe are led out from the outdoor refrigerant circuit,
A plurality of sets of indoor side branch gas pipes that are provided with an indoor heat exchanger that exchanges heat between the refrigerant and room air and an indoor expansion valve for cooling that expands the refrigerant, and are branched from the gas side pipe and the liquid side pipe And a plurality of indoor units connected in parallel with each other between the indoor branch liquid pipes, and a refrigerant sealing amount determination method for a multi air conditioning system,
The four-way switching valve is switched to a heating cycle, the low pressure and high pressure in the cycle are made constant, and the indoor unit is heated by heating all the indoor units with a constant refrigerant superheat degree at the outdoor heat exchanger outlet,
In this state, when the refrigerant subcooling degree at the outlet of the indoor heat exchanger is equal to or greater than a predetermined value, the refrigerant charging amount is determined to be an overcharged state. A compressor that compresses the refrigerant, a four-way switching valve that switches a refrigerant circulation direction, an outdoor heat exchanger that exchanges heat between the refrigerant and the outside air, an outdoor expansion valve for heating that expands the refrigerant, and a receiver that stores the refrigerant An outdoor refrigerant circuit configured by sequentially connecting a supercooling heat exchanger for imparting supercooling to the refrigerant and a supercooling expansion valve for expanding the bypass refrigerant led to the supercooling heat exchanger by refrigerant piping An outdoor unit from which the gas side pipe and the liquid side pipe are led out from the outdoor refrigerant circuit,
A plurality of sets of indoor side branch gas pipes that are provided with an indoor heat exchanger that exchanges heat between the refrigerant and room air and an indoor expansion valve for cooling that expands the refrigerant, and are branched from the gas side pipe and the liquid side pipe And a plurality of indoor units connected in parallel with each other between the indoor branch liquid pipes, and a refrigerant sealing amount determination method for a multi air conditioning system,
The gas low determination in the cooling cycle according to claim 1, the overcharge determination in the cooling cycle according to claim 2, the gas low determination in the heating cycle according to claim 3, and the heating according to claim 4. A method for determining a refrigerant filling amount of a multi-air conditioning system, wherein overcharge determination in a cycle is collectively performed in an appropriate order.   In summer, gas low judgment and overcharge judgment in the cooling cycle are given priority over gas low judgment and overcharge judgment in the heating cycle, and in winter, gas low judgment and overcharge judgment in the heating cycle are performed in the cooling cycle. 6. The method for determining the amount of refrigerant enclosed in a multi-air conditioning system according to claim 5, wherein the determination is performed with priority over the gas low determination and overcharge determination. During trial operation after installation of the multi air conditioning system, the refrigerant charging amount is determined by the refrigerant charging amount determination method according to any one of claims 1 to 6, the result is stored as initial operation data, and the same is performed at an appropriate time thereafter. A refrigerant leakage detection method for a multi-air-conditioning system, wherein the presence or absence of refrigerant leakage is detected by performing a refrigerant filling amount determination and comparing the operation data with the initial operation data.

Images