JP2015083894A - Refrigeration unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration unit capable of preventing an occurrence of backflow of a cooling medium during pressure equalization in a cooling medium circuit when starting up the unit.SOLUTION: An air-conditioning device 1 comprises a cooling medium circuit 2 where a capacity variable type compressor 11, an outdoor heat exchanger 13, a first electric expansion valve 14, a receiver 15, a second electric expansion valve 16 and an indoor heat exchanger 17 are sequentially connected. The air-conditioning device 1 also has a four-way switching valve 12 and a control device 5. The four-way switching valve 12 switches flow directions of a cooling medium circulating the cooling medium circuit 2. The control device 5 controls opening-closing states of the first electric expansion valve 14 and the second expansion valve 16. When starting up the air-conditioning device 1, the control device 5 determines which of the two electric expansion valves, the first electric expansion valve 14 and the second electric expansion valve 16, is a high voltage side electric valve positioned in a high voltage section of the cooling medium circuit 2 and fully opens the high voltage side electric valve.

Description

  The present invention relates to a refrigeration apparatus.

  Conventionally, a refrigeration apparatus including a receiver that temporarily stores liquid refrigerant compressed by a compression mechanism and cooled by a heat exchanger has been used. As an example, Patent Document 1 (Japanese Patent Laid-Open No. 9-72620) discloses a refrigeration apparatus in which motorized valves are provided on the upstream side and the downstream side of a receiver, respectively. The refrigeration apparatus further includes a gas injection channel for intermittently injecting the gas refrigerant separated by the receiver to the suction side of the compression mechanism. This refrigeration apparatus can prevent an abnormal increase in the discharge pressure of the compression mechanism accompanying an increase in the suction pressure of the compression mechanism due to gas injection by fully opening both of the two motor-operated valves immediately after startup.

  However, in this refrigeration apparatus, when both of the two motor-operated valves are fully opened in order to equalize the refrigerant circuit at the time of startup, the liquid refrigerant stored in the receiver does not evaporate and the compression mechanism passes through the motor-operated valve. There is a risk of liquid return, which is a phenomenon that is inhaled by the water.

  An object of the present invention is to provide a refrigeration apparatus capable of preventing the occurrence of liquid return when the refrigerant circuit is equalized during startup.

  The refrigerating apparatus according to the first aspect of the present invention is a refrigerant circuit in which a variable capacity compression mechanism, a first heat exchanger, a first electric valve, a receiver, a second electric valve, and a second heat exchanger are sequentially connected. It is a freezing apparatus provided with. The refrigeration apparatus includes a switching mechanism and a control unit. The switching mechanism switches the flow direction of the refrigerant circulating in the refrigerant circuit. A control part controls the opening-and-closing state of the 1st electric valve and the 2nd electric valve. The control unit determines whether the first motor-operated valve or the second motor-operated valve is the high-pressure side motor-operated valve located in the high-pressure unit of the refrigerant circuit when the refrigeration apparatus is started, and fully opens the high-pressure side motor-operated valve. To.

  This refrigeration apparatus includes a receiver for temporarily storing a refrigerant in a gas-liquid two-phase state. In the gas-liquid two-phase state, liquid refrigerant and gas refrigerant are mixed. Here, it is assumed that the first heat exchanger is a heat exchanger installed outdoors, and the second heat exchanger is a heat exchanger installed indoors. The switching mechanism switches between the cooling operation mode and the heating operation mode. In the cooling operation mode, the refrigerant circulates in the order of the compression mechanism, the first heat exchanger, the first electric valve, the receiver, the second electric valve, the second heat exchanger refrigerant, and the compression mechanism. In the heating operation mode, the refrigerant circulates in the order of the compression mechanism, the second heat exchanger, the second electric valve, the receiver, the first electric valve, the first heat exchanger, and the compression mechanism. The high pressure side motor operated valve is the first motor operated valve in the cooling operation mode, and is the second motor operated valve in the heating operation mode.

  In this refrigeration system, the refrigerant stored in the heat exchanger located in the high-pressure part of the refrigerant circuit is opened by fully opening the high-pressure side motor-operated valve and keeping the motor-operated valve that is not the high-pressure side motor-operated valve closed. The liquid refrigerant stored in the receiver is prevented from being sent to the suction side of the compression mechanism through the heat exchanger located in the low pressure portion of the refrigerant circuit. Therefore, this refrigeration apparatus can prevent the occurrence of liquid return, which is a phenomenon in which the liquid refrigerant stored in the receiver is sucked into the compression mechanism when equalizing the refrigerant circuit at the time of startup.

  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, based on the state of the switching mechanism, at the time of starting the refrigeration apparatus, It is determined which of the valves is a high pressure side motor operated valve.

  This refrigeration apparatus obtains the state of the switching mechanism and determines which of the first motor-operated valve and the second motor-operated valve is the high-pressure side motor-operated valve based on the state of the switching mechanism. The switching mechanism is, for example, a four-way switching valve for switching the flow direction of the refrigerant in the refrigerant circuit. This refrigeration apparatus can prevent occurrence of liquid return by equalizing the refrigerant circuit based on the state of the switching mechanism at the time of startup.

  The refrigeration apparatus according to the third aspect of the present invention is the refrigeration apparatus according to the first aspect or the second aspect, and the first motor-operated valve and the second motor-operated valve are in a closed state before the refrigeration apparatus is started. ing.

  In this refrigeration apparatus, since the first motor-operated valve and the second motor-operated valve are in a closed state before activation, the refrigerant is confined in the receiver.

  A refrigeration apparatus according to a fourth aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the third aspect, and the control unit fully opens the high-pressure side electric valve when the refrigeration apparatus is activated. Until this happens, the low-pressure side motor-operated valve located in the low-pressure part of the refrigerant circuit is closed.

  In this refrigeration system, at the time of start-up, the liquid refrigerant stored in the receiver passes through the low pressure side motorized valve by keeping the low pressure side motorized valve closed until the high pressure side motorized valve is fully opened. Inhalation by the compression mechanism can be prevented.

  A refrigeration apparatus according to a fifth aspect of the present invention is the refrigeration apparatus according to the fourth aspect, wherein the control unit gradually opens the low-pressure side electric valve after fully opening the high-pressure side electric valve when the refrigeration apparatus is started. Open to.

  At the time of start-up, this refrigeration apparatus opens the high-pressure side motor-operated valve and then gradually opens the low-pressure side motor-operated valve to equalize the refrigerant circuit. This refrigeration apparatus prevents the occurrence of liquid return by starting to open the low-pressure side electric valve after the high-pressure side electric valve is fully opened. In addition, this refrigeration system gradually opens the low-pressure side electric valve to gradually reduce the pressure difference between the heat exchanger located in the low-pressure part of the refrigerant circuit and the receiver, and is stored in the receiver. The liquid refrigerant is prevented from flowing suddenly toward the compression mechanism via the low pressure side electric valve.

  A refrigeration apparatus according to a sixth aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the fifth aspect, and the controller increases the capacity of the compression mechanism when the refrigeration apparatus is started. After starting, open the high pressure side motorized valve.

  At the time of startup, this refrigeration system sends as much refrigerant remaining in the refrigerant circuit as possible to the receiver before starting by opening the high-pressure side motorized valve after the refrigerant discharge capacity of the compression mechanism starts to increase from zero. Can do.

  A refrigeration apparatus according to a seventh aspect of the present invention is the refrigeration apparatus according to any one of the first to sixth aspects, further comprising a gas injection flow path and a gas injection valve, wherein the gas injection valve is The refrigeration apparatus is closed before the start-up. The gas injection flow path connects the receiver and the refrigerant suction side of the compression mechanism. The gas injection valve is provided in the gas injection flow path.

  In this refrigeration apparatus, the liquid refrigerant stored in the receiver is prevented from flowing into the suction side of the compression mechanism through the gas injection flow path by closing the gas injection valve before starting.

  A refrigeration apparatus according to an eighth aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the seventh aspect, wherein a predetermined time has elapsed after the start of the refrigeration apparatus, or from a compression mechanism Normal operation is started after the temperature of the discharged refrigerant reaches the first temperature.

  This refrigeration apparatus can start normal operation after the refrigerant circuit is sufficiently equalized at the time of startup.

  The refrigeration apparatus according to the first aspect can prevent the occurrence of liquid return when the refrigerant circuit is equalized during startup.

  The refrigeration apparatus according to the second aspect can prevent the occurrence of liquid return by equalizing the refrigerant circuit based on the state of the switching mechanism at the time of startup.

  The refrigeration apparatus according to the third aspect can be in a state where the refrigerant is confined in the receiver before activation.

  The refrigeration apparatus according to the fourth aspect can prevent the liquid refrigerant stored in the receiver from being sucked into the compression mechanism through the low-pressure side electric valve during startup.

  In the refrigeration apparatus according to the fifth aspect, the liquid refrigerant stored in the receiver suddenly flows toward the compression mechanism via the low-pressure side motor-operated valve by gradually opening the low-pressure side motor-operated valve at the time of startup. To prevent.

  The refrigeration apparatus according to the sixth aspect can send as much refrigerant remaining in the refrigerant circuit as possible to the receiver before activation.

  The refrigeration apparatus according to the seventh aspect can prevent the liquid refrigerant stored in the receiver from flowing into the suction side of the compression mechanism through the gas injection flow path before startup.

  The refrigeration apparatus according to the eighth aspect can start normal operation after the refrigerant circuit is sufficiently equalized at the time of startup.

It is a block diagram of the air harmony device concerning an embodiment. It is a Mollier diagram of a refrigerant showing the refrigerating cycle of an air harmony device. It is a graph showing the time change of the opening degree of a high voltage | pressure side electric valve and a low voltage | pressure side electric valve. It is a graph showing the time change of the opening degree of the high voltage | pressure side motor operated valve and the low voltage | pressure side motor operated valve in the modification A. It is a graph showing the time change of the opening degree of the high voltage | pressure side motor operated valve and the low voltage | pressure side motor operated valve in the modification D. It is a block diagram of an air harmony device in modification E.

(1) Configuration of Air Conditioner A refrigeration apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an air conditioner 1 that is a refrigeration apparatus according to the present embodiment. The air conditioner 1 is a device that performs a cooling operation and a heating operation using a chlorofluorocarbon refrigerant such as R410A and R32. The air conditioner 1 mainly includes a refrigerant circuit 2, an indoor fan 3, an outdoor fan 4, and a control device 5. The refrigerant circuit 2 mainly includes a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, a first electric expansion valve 14, a receiver 15, a second electric expansion valve 16, and an indoor heat exchanger 17. Each apparatus which comprises the refrigerant circuit 2 is connected through refrigerant | coolant piping.

  The air conditioner 1 is a separation-type air conditioner that includes an outdoor unit 10 and an indoor unit 20. The outdoor unit 10 mainly includes a compressor 11, a four-way switching valve 12, an outdoor heat exchanger 13, a first electric expansion valve 14, a receiver 15, a second electric expansion valve 16, an outdoor fan 4, and a control device 5. The indoor unit 20 mainly includes the indoor heat exchanger 17 and the indoor fan 3. As shown in FIG. 1, the outdoor unit 10 is connected to the indoor unit 20 via a first communication pipe 31 and a second communication pipe 32. Next, each device constituting the refrigerant circuit 2 will be described.

  The compressor 11 is connected to a suction pipe 11a and a discharge pipe 11b that are part of the refrigerant pipe. The compressor 11 sucks and compresses low-pressure gas refrigerant from the suction pipe 11a, and discharges high-temperature and high-pressure refrigerant to the discharge pipe 11b. The compressor 11 is a variable capacity compressor that can control the rotation speed of the motor.

  The four-way switching valve 12 is a valve for switching the flow direction of the refrigerant in the refrigerant circuit 2 according to the operation mode. The operation mode includes a cooling operation mode for performing a cooling operation and a heating operation mode for performing a heating operation. In the four-way switching valve 12 shown in FIG. 1, the solid line represents the flow path in the cooling operation mode, and the dotted line represents the flow path in the heating operation mode. The four-way switching valve 12 connects the discharge pipe 11b of the compressor 11 and the outdoor heat exchanger 13 and connects the suction pipe 11a of the compressor 11 and the indoor heat exchanger 17 in the cooling operation mode. The four-way switching valve 12 connects the discharge pipe 11b of the compressor 11 and the indoor heat exchanger 17 and connects the suction pipe 11a of the compressor 11 and the outdoor heat exchanger 13 in the heating operation mode.

  In the cooling operation mode, the refrigerant is the compressor 11, the four-way switching valve 12, the outdoor heat exchanger 13, the first electric expansion valve 14, the receiver 15, the second electric expansion valve 16, the indoor heat exchanger 17, and the four-way switching valve 12. And the compressor 11 are circulated in this order. In the heating operation mode, the refrigerant is the compressor 11, the four-way switching valve 12, the indoor heat exchanger 17, the second electric expansion valve 16, the receiver 15, the first electric expansion valve 14, the outdoor heat exchanger 13, and the four-way switching valve 12. And the compressor 11 are circulated in this order.

  The outdoor heat exchanger 13 performs heat exchange between the high-temperature and high-pressure refrigerant discharged from the compressor 11 and outdoor air in which the outdoor unit 10 is installed in the cooling operation mode. In the cooling operation mode, the high-temperature and high-pressure refrigerant flowing through the outdoor heat exchanger 13 is cooled. In the heating operation mode, the outdoor heat exchanger 13 performs heat exchange between the liquid refrigerant that has been decompressed through the first electric expansion valve 14 and outdoor air. In the heating operation mode, the liquid refrigerant flowing through the outdoor heat exchanger 13 is heated and evaporates.

  The first electric expansion valve 14 decompresses the refrigerant flowing in from the outdoor heat exchanger 13 in the cooling operation mode. The first electric expansion valve 14 decompresses the liquid refrigerant flowing from the receiver 15 in the heating operation mode.

  The receiver 15 stores a surplus refrigerant for the refrigerant circuit 2 according to the operation mode and the air conditioning load.

  The second electric expansion valve 16 decompresses the liquid refrigerant flowing from the receiver 15 in the cooling operation mode. The second electric expansion valve 16 depressurizes the refrigerant flowing from the indoor heat exchanger 17 in the heating operation mode.

  The indoor heat exchanger 17 is connected to the second electric expansion valve 16 via the first communication pipe 31 and is connected to the four-way switching valve 12 via the second communication pipe 32.

  In the cooling operation mode, the indoor heat exchanger 17 exchanges heat between the liquid refrigerant that has been decompressed through the second electric expansion valve 16 and the air in the room where the indoor unit 20 is installed. In the cooling operation mode, the liquid refrigerant flowing through the indoor heat exchanger 17 is heated by heat exchange to become a gas refrigerant and is sent to the suction pipe 11a of the compressor 11. In the cooling operation mode, the indoor air is cooled by heat exchange in the indoor heat exchanger 17 and becomes conditioned air.

  In the heating operation mode, the indoor heat exchanger 17 exchanges heat between the high-temperature and high-pressure refrigerant flowing from the discharge pipe 11b of the compressor 11 and the indoor air in which the indoor unit 20 is installed. In the heating operation mode, the high-temperature and high-pressure refrigerant flowing through the indoor heat exchanger 17 is cooled by heat exchange and sent to the receiver 15. In the heating operation mode, indoor air is heated by heat exchange in the indoor heat exchanger 17 to become conditioned air.

  The indoor fan 3 is installed in the vicinity of the indoor heat exchanger 17 inside the indoor unit 20. The indoor fan 3 is a fan for sending indoor air into the indoor unit 20 and exhausting the air exchanged with the refrigerant flowing through the indoor heat exchanger 17 into the room. The air exhausted indoors by the indoor fan 3 is conditioned air cooled in the cooling operation mode and heated conditioned air in the heating operation mode.

  The outdoor fan 4 is installed in the vicinity of the outdoor heat exchanger 13 inside the outdoor unit 10. The outdoor fan 4 is a fan for sending outdoor air into the outdoor unit 10 and exhausting the air heat-exchanged with the refrigerant flowing through the outdoor heat exchanger 13 to the outside.

  The control device 5 is a computer connected to the compressor 11, the four-way switching valve 12, the first electric expansion valve 14, the second electric expansion valve 16, the indoor fan 3, the outdoor fan 4, and the like via a communication line. . The control device 5 includes the capacity of the compressor 11, the state of the four-way switching valve 12, the opening degree of the first electric expansion valve 14, the opening degree of the second electric expansion valve 16, the rotational speed of the indoor fan 3, and the outdoor fan 4. The number of rotations can be acquired and controlled. The capacity of the compressor 11 is, for example, the refrigerant discharge amount per unit time or the rotation speed of the motor provided in the compressor 11. The state of the four-way switching valve 12 is information indicating whether the air conditioner 1 is in the cooling operation mode or the heating operation mode. The control device 5 acquires various types of data from each device constituting the refrigerant circuit 2 and controls the opening degree of the first electric expansion valve 14 and the opening degree of the second electric expansion valve 16.

(2) Operation of Air Conditioner The operation of the air conditioner 1 in the cooling operation mode and the heating operation mode will be described with reference to FIGS. 1 and 2. FIG. 2 is a Mollier diagram (pressure-enthalpy diagram) of the refrigerant representing the refrigeration cycle of the air conditioner 1. FIG. 2 shows a dry saturated vapor line L1 of the refrigerant and a saturated liquid line L2 of the refrigerant. Refrigerant states indicated by reference signs A to E shown in FIG. 2 respectively correspond to refrigerant states in the cooling operation mode indicated by reference signs A to E in FIG.

  In FIG. 2, A → B represents the compression stroke of the gas refrigerant, B → C represents the cooling stroke of the refrigerant, C → D1 represents the first expansion stroke of the refrigerant, and D2 → E represents the second expansion stroke of the refrigerant. Where E → A represents the evaporation process of the refrigerant. The air conditioner 1 repeats the refrigeration cycle of A → B → C → D1 → D2 → E → A during operation.

  In FIG. 2, D <b> 1 and D <b> 2 represent the state of the refrigerant in the receiver 15. D1 represents the gas-liquid two-phase refrigerant flowing into the receiver 15. D2 represents a saturated liquid refrigerant that is stored in the receiver 15 and flows out of the receiver 15. D2 is located on the saturated liquid line L2.

(2-1) Cooling Operation Mode In the cooling operation mode, the four-way switching valve 12 is in a state indicated by a solid line in FIG. That is, the discharge side of the compressor 11 is connected to the high temperature side of the outdoor heat exchanger 13, and the suction side of the compressor 11 is connected to the high temperature side of the indoor heat exchanger 17.

  In the cooling operation mode, when the compressor 11 is started, the low-pressure gas refrigerant is sucked into the compressor 11 and compressed, and the high-temperature and high-pressure gas refrigerant is discharged from the compressor 11. Next, the high-temperature and high-pressure gas refrigerant is sent to the outdoor heat exchanger 13 via the four-way switching valve 12 and is cooled in the outdoor heat exchanger 13 to become a liquid refrigerant. Next, the liquid refrigerant passes through the first electric expansion valve 14 and is depressurized to become a gas-liquid two-phase refrigerant. Next, the gas-liquid two-phase refrigerant is sent to the receiver 15, and a part of the refrigerant is stored in the receiver 15 as a liquid refrigerant. Next, the liquid refrigerant that has flowed out of the receiver 15 passes through the second electric expansion valve 16 and is reduced in pressure to become a gas-liquid two-phase refrigerant. Next, the gas-liquid two-phase refrigerant is heated and evaporated in the indoor heat exchanger 17 to become a gas refrigerant. In the indoor heat exchanger 17, the indoor air is cooled by heat exchange between the refrigerant and the indoor air. Next, the gas refrigerant is sucked into the compressor 11 again via the four-way switching valve 12. The control device 23 controls each device of the air conditioner 1 in order to execute the above control in the cooling operation mode.

(2-2) Heating operation mode In the heating operation mode, the four-way switching valve 12 is in a state indicated by a dotted line in FIG. That is, the discharge side of the compressor 11 is connected to the high temperature side of the indoor heat exchanger 17, and the suction side of the compressor 11 is connected to the high temperature side of the outdoor heat exchanger 13.

  In the heating operation mode, when the compressor 11 is started, the low-pressure gas refrigerant is sucked into the compressor 11 and compressed, and the high-temperature and high-pressure gas refrigerant is discharged from the compressor 11. Next, the high-temperature and high-pressure gas refrigerant is sent to the indoor heat exchanger 17 via the four-way switching valve 12 and is cooled in the indoor heat exchanger 17 to become a liquid refrigerant. In the indoor heat exchanger 17, the indoor air is heated by heat exchange between the refrigerant and the indoor air. Next, the liquid refrigerant passes through the second electric expansion valve 16 and is depressurized to become a gas-liquid two-phase refrigerant. Next, the gas-liquid two-phase refrigerant is sent to the receiver 15, and a part of the refrigerant is stored in the receiver 15 as a liquid refrigerant. Next, the liquid refrigerant that has flowed out of the receiver 15 passes through the first electric expansion valve 14 and is reduced in pressure to become a gas-liquid two-phase refrigerant. Next, the gas-liquid two-phase refrigerant is heated and evaporated in the outdoor heat exchanger 13 to become a gas refrigerant. Next, the gas refrigerant is sucked into the compressor 11 again via the four-way switching valve 12. The control device 23 controls each device of the air conditioner 1 in order to execute the above control in the heating operation mode.

(2-3) Control of the first electric expansion valve and the second electric expansion valve Before the air conditioning apparatus 1 is activated, the first electric expansion valve 14 and the second electric expansion valve 16 are closed. At the start of operation of the air conditioner 1, the control device 5 fully opens the high-pressure side motor-operated valve located in the high-pressure portion of the refrigerant circuit 2, and the low-pressure side electric motor located in the low-pressure portion of the refrigerant circuit 2. Control to keep the valve closed. The high-pressure side electric valve is an electric expansion valve through which high-temperature and high-pressure refrigerant passes. The high pressure side electric valve is the first electric expansion valve 14 in the cooling operation mode, and the second electric expansion valve 16 in the heating operation mode.

  When the air conditioner 1 is activated, the control device 5 determines which one of the first electric expansion valve 14 and the second electric expansion valve 16 is the high-pressure side electric valve, and fully opens the high-pressure side electric valve. . Specifically, the control device 5 acquires the state of the four-way switching valve 12 and determines whether the air conditioner 1 is in the cooling operation mode or the air conditioner 1 is in the heating operation mode. At the start of operation of the air conditioner 1, the control device 5 determines that the air conditioner 1 is in the cooling operation mode when the four-way switching valve 12 is in the state indicated by the solid line in FIG. The first electric expansion valve 14 which is an electric valve is fully opened, and the second electric expansion valve 16 which is a low pressure side electric valve is kept closed. Conversely, when the four-way switching valve 12 is in the state indicated by the dotted line in FIG. 1, the control device 5 determines that the air conditioner 1 is in the heating operation mode, and the second electric motor that is the high-pressure side motor operated valve. The expansion valve 16 is fully opened, and the first electric expansion valve 14 that is a low-pressure side electric valve is kept closed.

  Further, at the time of starting the operation of the air conditioner 1, the control device 5 keeps the low-pressure side motor-operated valve closed until the high-pressure side motor-operated valve is fully opened, and after the high-pressure side motor-operated valve is fully opened. Control to gradually open the low-pressure motorized valve. In the cooling operation mode, the control device 5 keeps the second electric expansion valve 16 closed until the first electric expansion valve 14 is fully opened, and after the first electric expansion valve 14 is fully opened, 2. Control to gradually open the electric expansion valve 16 is performed. In the heating operation mode, the control device 5 keeps the first electric expansion valve 14 closed until the second electric expansion valve 16 is fully opened, and after the second electric expansion valve 16 is fully opened, 1 Control is performed to gradually open the electric expansion valve 14. FIG. 3 is a graph showing temporal changes in the opening degrees of the high-pressure side motor-operated valve and the low-pressure side motor-operated valve when the air conditioner 1 is activated. The upper graph of FIG. 3 represents the time change EV1 of the opening degree of the high-pressure side electric valve. The lower graph of FIG. 3 represents the time change EV2 of the opening degree of the low pressure side electric valve. In FIG. 3, the horizontal axis represents time, and the vertical axis represents the opening degree (%) of the high-pressure side motor-operated valve and the low-pressure side motor-operated valve. Both graphs in FIG. 3 have a common horizontal axis. The high-pressure side electric valve and the low-pressure side electric valve are completely closed when the opening degree is 0%, and are fully opened when the opening degree is 100%. The time point t1 when the opening degree of the high-pressure side electric valve becomes 100% is a time point when the opening degree of the low-pressure side electric valve starts to increase from 0%. The opening degree of the low-pressure side electric valve increases stepwise from 0% to 100%. The time point t2 when the opening of the low-pressure side electric valve becomes 100% is the time point when the pressure equalization of the refrigerant circuit 2 is completed.

(3) Features In the refrigerant circuit 2 of the air conditioner 1, the receiver 15 is sandwiched between the first electric expansion valve 14 and the second electric expansion valve 16. The first electric expansion valve 14 and the second electric expansion valve 16 are closed when the operation of the air conditioner 1 is stopped. Therefore, when the air conditioner 1 is activated, the refrigerant circuit 2 includes a portion with a high refrigerant pressure and a portion with a low refrigerant pressure. The air conditioner 1 needs to equalize the refrigerant circuit 2 at the start of operation in order to avoid a sudden change in the refrigerant pressure of the refrigerant circuit 2 at the start of operation.

  The air conditioner 1 fully opens the first electric expansion valve 14 that is a high-pressure side electric valve and keeps the second electric expansion valve 16 that is a low-pressure side electric valve closed when the operation is started in the cooling operation mode. As a result, the refrigerant stored in the outdoor heat exchanger 13 is sent to the receiver 15, and the liquid refrigerant stored in the receiver 15 passes through the indoor heat exchanger 17 and is sent to the suction pipe 11 a of the compressor 11. To prevent it. On the other hand, when the air conditioner 1 is activated in the heating operation mode, the second electric expansion valve 16 that is the high-pressure side electric valve is fully opened and the first electric expansion valve 14 that is the low-pressure side electric valve is closed. By leaving the liquid refrigerant stored in the indoor heat exchanger 17 to the receiver 15, the liquid refrigerant stored in the receiver 15 passes through the outdoor heat exchanger 13 and sucks the suction pipe of the compressor 11. It is prevented from being sent to 11a. When liquid return occurs, which is a phenomenon in which the liquid refrigerant stored in the receiver 15 is sucked into the compressor 11, it causes a failure of the compressor 11. Therefore, the air conditioner 1 can prevent the occurrence of liquid return when the refrigerant circuit 2 is equalized when the operation is started.

  Further, the control device 5 of the air conditioner 1 determines which of the first electric expansion valve 14 and the second electric expansion valve 16 is a high-pressure side electric valve based on the state of the four-way switching valve 12. Therefore, the control device 5 fully opens the high-pressure side electric valve when starting the operation of the air conditioner 1 without having to memorize whether the current operation mode is the cooling operation mode or the heating operation mode. The opening degree control can be performed to keep the side electric valve closed.

  Further, immediately after the operation mode is switched using a remote controller or the like that controls the air conditioner 1, the state of the four-way switching valve 12 corresponding to the operation mode stored in the remote control or the like and the actual state of the four-way switching valve 12 May not match. However, the control device 5 acquires the actual state of the four-way switching valve 12, and determines which of the first electric expansion valve 14 and the second electric expansion valve 16 is the high-pressure side electric valve. The opening degree control can be reliably performed. Therefore, the air conditioning apparatus 1 can reliably prevent the occurrence of liquid return at the start of operation.

  Further, the control device 5 keeps the refrigerant in the receiver 15 by closing both the first electric expansion valve 14 and the second electric expansion valve 16 before starting the operation of the air conditioner 1. be able to.

  In addition, when the air conditioner 1 is activated, the control device 5 starts opening the low-pressure side motor valve after fully opening the high-pressure side motor valve, so that the receiver 15 in the process of pressure equalization of the refrigerant circuit 2 It is possible to prevent the stored liquid refrigerant from being sucked into the compressor 11 via the low-pressure side electric valve.

  In addition, the control device 5 gradually opens the low-pressure side electric valve after fully opening the high-pressure side motor-operated valve when starting the operation of the air conditioner 1, so that the receiver 15 in the process of pressure equalization of the refrigerant circuit 2 is performed. It is possible to prevent the liquid refrigerant stored in the tank from abruptly flowing toward the compressor 11 via the low-pressure electric valve. Since there is a refrigerant pressure difference between the upstream and downstream piping of the low-pressure side motorized valve, sudden opening of the low-pressure side motorized valve will cause a large amount of refrigerant to be There is a risk of liquid return passing through the motor-operated valve. The control device 5 can prevent the occurrence of liquid return by performing control to increase the opening degree of the low pressure side electric valve in a stepwise manner.

(4) Modification The specific configuration of the present embodiment can be changed without departing from the gist of the present invention. Hereinafter, modified examples applicable to the present embodiment will be described.

(4-1) Modification A
In the present embodiment, the control device 5 increases the opening degree of the low-pressure side electric valve stepwise from 0% to 100% after fully opening the high-pressure side electric valve. However, the control device 5 may gradually increase the opening degree of the low-pressure side electric valve from 0% to 100% after fully opening the high-pressure side electric valve. FIG. 4 is a graph showing temporal changes in the opening degrees of the high-pressure side electric valve and the low-pressure side electric valve in the present modification. The upper graph of FIG. 4 represents the time change EV1 of the opening degree of the high-pressure side electric valve. The lower graph of FIG. 4 represents the time change EV2 of the opening degree of the low pressure side electric valve. In FIG. 4, the horizontal axis represents time, and the vertical axis represents the opening degree (%) of the high-pressure side motor-operated valve and the low-pressure side motor-operated valve. Both graphs in FIG. 4 have a common horizontal axis. The time point t1 when the opening degree of the high pressure side electric valve becomes 100% is a time point when the opening degree of the low pressure side electric valve starts to increase from 0%. The opening degree of the low-pressure side electric valve gradually increases from 0% to 100%. The time point t2 when the opening of the low-pressure side electric valve becomes 100% is the time point when the pressure equalization of the refrigerant circuit 2 is completed.

(4-2) Modification B
In the present embodiment, the control device 5 may further perform control to fully open the high-pressure side electric valve after the capacity of the compressor 11 starts to increase when the air conditioner 1 is activated. For example, the control device 5 performs control to fully open the high-pressure side electric valve after the time when the rotation speed of the motor of the compressor 11 starts to increase from zero or after the time when high-pressure refrigerant starts to be discharged from the compressor 11. You may go.

  In this modification, the refrigerant remaining in the refrigerant circuit 2 is increased as much as possible before the operation of the air conditioner 1 is started by fully opening the high-pressure electric valve after the refrigerant discharge capacity of the compressor 11 starts to increase. It can be sent to the receiver 15.

(4-3) Modification C
In the present embodiment, the control device 5 further, after the operation of the air conditioner 1 is started, after a predetermined time has elapsed or after the temperature of the refrigerant discharged from the compression mechanism 11 has increased to a predetermined target value. In addition, control for starting normal operation may be performed. The normal operation is an operation in which the air conditioner 1 harmonizes indoor air. Thereby, the control apparatus 5 can start a normal driving | operation after the refrigerant circuit 2 is fully equalized at the time of the driving | running start of the air conditioning apparatus 1. FIG.

  Further, the control device 5 may perform control to reduce the opening degree of the high-pressure side electric valve from 100% to a predetermined opening degree when the pressure equalization of the refrigerant circuit 2 is completed and the normal operation is started. Here, the predetermined opening is an operating mode of the air conditioner 1 or an opening set in advance according to a target value of the degree of supercooling of the refrigerant or an operating condition of the air conditioner 1. Accordingly, the opening is appropriately determined, and is a value greater than 0% and less than 100%.

  In addition, after fully opening the high pressure side electric valve, the control device 5 increases the opening degree of the high pressure side electric valve from 100% to a predetermined opening degree while increasing the opening degree of the low pressure side electric valve from 0%. You may perform control to reduce to. Here, the predetermined opening is an opening that is preset according to the operation mode of the air conditioner 1 or an opening that is appropriately determined according to the operating conditions of the air conditioner 1. , Greater than 0% and less than 100%.

(4-4) Modification D
In the present embodiment, the control device 5 performs control to increase the opening degree of the low-pressure side electric valve stepwise from 0% to 100% after fully opening the high-pressure side electric valve. However, the control device 5 may perform control to gradually increase the opening degree of the low-pressure side electric valve from 0% to a predetermined opening degree after the high-pressure side electric valve is fully opened. Here, the predetermined opening degree corresponds to the operation mode of the air conditioner 1, the opening degree set in advance according to the target value of the dryness of the refrigerant, or the operating condition of the air conditioner 1. The opening is appropriately determined and is a value greater than 0% and less than 100%. In this case, when the pressure equalization of the refrigerant circuit 2 is completed and normal operation is started, the opening of the low-pressure side electric valve is a predetermined opening smaller than 100%. The control device 5 may perform control to gradually increase the opening degree of the low pressure side electric valve from 0% to a predetermined opening degree after fully opening the high pressure side electric valve.

  Further, the opening degree control of the present modification may be combined with the opening degree control of Modification C. FIG. 5 is a graph showing temporal changes in the opening degrees of the high-pressure side motor-operated valve and the low-pressure side motor-operated valve as an example. The upper graph in FIG. 5 represents the time change EV1 of the opening degree of the high-pressure side electric valve. The lower graph of FIG. 5 represents the time change EV2 of the opening degree of the low pressure side electric valve. In FIG. 5, the horizontal axis represents time, and the vertical axis represents the opening degree (%) of the high-pressure side motor-operated valve and the low-pressure side motor-operated valve. Both graphs in FIG. 5 have a common horizontal axis. The time point t1 when the opening degree of the high-pressure side electric valve becomes 100% is a time point when the opening degree of the low-pressure side electric valve starts to increase from 0%. The opening degree of the low-pressure side electric valve increases stepwise from 0% to 40%. In FIG. 5, a time point t2 when the opening of the low-pressure side electric valve becomes 40% is a time point when the pressure equalization of the refrigerant circuit 2 is completed. At the time t2, the opening degree of the high-pressure side electric valve decreases from 100% to 60%.

  It should be noted that the time when the pressure equalization of the refrigerant circuit 2 is completed may not coincide with the time when the opening of the low-pressure side electric valve becomes a predetermined opening. For example, in FIG. 5, the time point t <b> 2 when the opening of the low-pressure electric valve becomes 40% may not be the time point when the refrigerant circuit 2 is equalized.

(4-5) Modification E
In the present embodiment, the refrigerant circuit 2 may further include a gas injection flow path for injecting a gas refrigerant into the suction pipe 11 a of the compressor 11. FIG. 6 is a block diagram of the air conditioning apparatus 101 in the present modification. The air conditioner 101 further includes a gas injection pipe 18, a gas injection valve 19, and a capillary tube 21 in addition to the devices included in the air conditioner 1 of the present embodiment. In FIG. 6, the same reference numerals as those shown in FIG. 1 are given to the components common to the air conditioner 1 of the present embodiment. Hereinafter, the difference between the air conditioning apparatus 101 and the air conditioning apparatus 1 of the present embodiment will be mainly described.

  The gas injection pipe 18 is a pipe that connects the receiver 15 and the suction pipe 11 a of the compressor 11. The gas injection pipe 18 is a pipe for injecting the gas refrigerant stored in the receiver 15 into the suction pipe 11 a of the compressor 11. By injecting the refrigerant through the gas injection pipe 18, it is possible to adjust the refrigerant amount in the receiver 15 and the dryness and superheat degree of the refrigerant sucked into the compressor 11.

  The gas injection valve 19 is an electromagnetic valve attached to the gas injection pipe 18. During the operation of the air conditioner 1, the pressure of the gas refrigerant stored in the receiver 15 is higher than the pressure of the gas refrigerant flowing through the suction pipe 11 a of the compressor 11. When the gas injection valve 19 is open, the gas refrigerant stored in the receiver 15 is supplied to the suction pipe 11 a of the compressor 11 via the gas injection pipe 18 and the capillary tube 21. When the gas injection valve 19 is closed, the gas refrigerant stored in the receiver 15 is not supplied to the suction pipe 11 a of the compressor 11. Before the operation of the air conditioner 1 is started, the gas injection valve 19 is closed in order to prevent the refrigerant stored in the receiver 15 from returning to the compressor 11.

  The capillary tube 21 is a thin tube attached to the gas injection tube 18. As illustrated in FIG. 6, the capillary tube 21 is attached between the gas injection valve 19 and the suction pipe 11 a of the compressor 11. The capillary tube 21 acts as the expansion of the refrigerant and the resistance of the refrigerant flow. The pressure of the refrigerant decreases as it passes through the capillary tube 21.

  In the cooling operation mode, the opening of the gas injection valve 19 is increased to increase the amount of refrigerant flowing through the gas injection pipe 18. Thereby, the temperature of the refrigerant sucked by the compressor 11 can be lowered, and the temperature rise of the compressor 11 can be suppressed. On the other hand, in the heating operation mode, the opening of the gas injection valve 19 is decreased to reduce the amount of refrigerant flowing through the gas injection pipe 18. Accordingly, the flow rate of the refrigerant passing through the indoor heat exchanger 17 is increased as much as possible while preventing the temperature of the refrigerant sucked by the compressor 11 from being reduced as much as possible, thereby improving the efficiency of heat exchange of the indoor heat exchanger 17. Can be made.

  In this modification, the control device 5 can further control the opening degree of the gas injection valve 19. The control device 5 keeps the gas injection valve 19 closed before the air conditioner 101 is activated. This prevents the liquid refrigerant stored in the receiver 15 from passing through the gas injection pipe 18 and flowing into the suction pipe 11a of the compressor 11. Therefore, the air conditioning apparatus 101 can prevent the occurrence of liquid return when the refrigerant circuit 2 is equalized when the operation is started.

  The refrigeration apparatus according to the present invention can prevent the occurrence of liquid return when the refrigerant circuit is equalized during startup.

1 Air conditioning equipment (refrigeration equipment)
2 Refrigerant circuit 5 Control device (control unit)
11 Compressor (compression mechanism)
12 Four-way switching valve (switching mechanism)
13 Outdoor heat exchanger (first heat exchanger)
14 First electric expansion valve (first electric valve)
15 Receiver 16 Second electric expansion valve (second electric valve)
17 Indoor heat exchanger (second heat exchanger)
18 Gas injection pipe (gas injection flow path)
19 Gas injection valve

JP-A-9-72620

Claims (8)

The compression mechanism (11), the first heat exchanger (13), the first electric valve (14), the receiver (15), the second electric valve (16) and the second heat exchanger (17), which are variable capacity types, are provided. A refrigeration apparatus comprising a refrigerant circuit (2) connected in sequence,
A switching mechanism (12) for switching the flow direction of the refrigerant circulating in the refrigerant circuit;
A control unit (5) for controlling an open / closed state of the first electric valve and the second electric valve;
With
The control unit determines whether the first motor-operated valve or the second motor-operated valve is a high-pressure side motor-operated valve located in a high-pressure unit of the refrigerant circuit at the time of starting the refrigeration apparatus, Fully open the high pressure side motorized valve,
Refrigeration equipment (1). The control unit determines which of the first motor-operated valve and the second motor-operated valve is the high-pressure side motor-operated valve based on the state of the switching mechanism when the refrigeration apparatus is activated.
The refrigeration apparatus according to claim 1. The first electric valve and the second electric valve are in a closed state before the refrigeration apparatus is started.
The refrigeration apparatus according to claim 1 or 2. The control unit closes the low-pressure side motor valve located in the low-pressure part of the refrigerant circuit until the high-pressure side motor valve is fully opened when the refrigeration apparatus is started.
The refrigeration apparatus according to any one of claims 1 to 3. The control unit gradually opens the low-pressure side electric valve after fully opening the high-pressure side electric valve at the time of starting the refrigeration apparatus,
The refrigeration apparatus according to claim 4. The control unit opens the high-pressure side electric valve after the capacity of the compression mechanism starts to increase at the time of starting the refrigeration apparatus,
The refrigeration apparatus according to any one of claims 1 to 5. A gas injection flow path (18) connecting the receiver and the refrigerant suction side of the compression mechanism;
A gas injection valve (19) provided in the gas injection flow path;
Further comprising
The gas injection valve is in a closed state before the refrigeration apparatus is activated,
The refrigeration apparatus according to any one of claims 1 to 6. After starting the refrigeration apparatus, after a predetermined time has elapsed, or after the temperature of the refrigerant discharged from the compression mechanism reaches the first temperature, normal operation is started.
The refrigeration apparatus according to any one of claims 1 to 7.

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