JP2015083895A - Refrigeration unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration unit capable of preventing overheating operation of a heat exchanger at a downstream side during heating operation.SOLUTION: An air-conditioning device 1 comprises a cooling medium circuit where a 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, a gas injection pipe 18, a gas injection valve 19, a control device 5 and an outdoor air temperature measuring device 6. The gas injection pipe 18 connects the receiver 15 and a cooling medium intake side of the compressor 11. The control device 5 controls an opening-closing state of the gas injection valve 19 installed on the gas injection pipe 18. The control device 5 closes the gas injection valve 19 when a control condition is met during heating operation. The control condition requires an outdoor air temperature measured by the outdoor air temperature measuring device 6 to be lower than a first temperature.

Description

  The present invention relates to a refrigeration apparatus.

  Conventionally, a receiver that temporarily stores liquid refrigerant compressed by a compression mechanism and cooled by a heat exchanger, and gas injection for intermittently injecting gas refrigerant separated by the receiver to the suction side of the compression mechanism A refrigeration apparatus having a flow path is used. In such a refrigeration apparatus, for example, as disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2006-200890), a throttle mechanism capable of adjusting the opening degree is provided on each of the upstream side and the downstream side of the receiver, A two-way valve that can be opened and closed is provided in the middle of the injection flow path. In the refrigeration apparatus disclosed in Patent Document 1, in order to prevent performance deterioration due to liquid return, which is a phenomenon in which liquid refrigerant stored in a receiver is injected into the suction side of the compression mechanism, the outside air temperature is a predetermined value during cooling operation. When the temperature is lower, or when the outside air temperature is higher than a predetermined value during heating operation, control is performed to close the two-way valve of the gas injection flow path. In addition, this refrigeration apparatus has a downstream throttling mechanism in order to ensure a difference between the refrigerant evaporation temperature in the downstream heat exchanger and the outside air temperature when the outside air temperature is low during heating operation. The control which suppresses the opening degree of is performed.

  However, if the opening of the downstream throttle mechanism is suppressed, the opening of the two-way valve in the gas injection flow path becomes larger than the opening of the downstream throttle mechanism, and the refrigerant in the receiver flows through the gas injection flow path. It becomes easy. As a result, the amount of refrigerant supplied to the downstream heat exchanger decreases, and the downstream heat exchanger may overheat. In order to secure the amount of refrigerant supplied to the downstream heat exchanger, it is necessary to close the two-way valve of the gas injection flow path. However, in the refrigeration apparatus disclosed in Patent Document 1, the outside air temperature is low. Even in this case, the two-way valve may be open, and there is a possibility that the overheat operation of the downstream heat exchanger cannot be avoided.

  An object of the present invention is to provide a refrigeration apparatus that can prevent an overheating operation of a downstream heat exchanger during a heating operation.

  A refrigeration apparatus according to a first aspect of the present invention is a refrigeration apparatus including a refrigerant circuit to which a compression mechanism, a first heat exchanger, a first throttle mechanism, a receiver, a second throttle mechanism, and a second heat exchanger are sequentially connected. is there. The refrigeration apparatus includes a switching mechanism, a gas injection flow path, a gas injection valve, a control unit, and an outside air temperature measurement unit. The switching mechanism switches the flow direction of the refrigerant circulating in the refrigerant circuit. 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. The control unit controls the open / closed state of the gas injection valve. The outside air temperature measurement unit measures the outside air temperature. The control unit closes the gas injection valve when the control condition is satisfied during the heating operation. The control condition is that the outside air temperature measured by the outside air temperature measurement unit is lower than the first temperature.

  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 throttle mechanism, the receiver, the second throttle mechanism, 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 throttle mechanism, the receiver, the first throttle mechanism, the first heat exchanger, and the compression mechanism. The gas injection channel is a channel for intermittently injecting the refrigerant in the receiver to the suction side of the compression mechanism. The gas injection flow path is a pipe that connects the receiver and the suction pipe of the compression mechanism.

  This refrigeration apparatus performs control to close the gas injection valve when the outside air temperature is lower than a predetermined first temperature during heating operation. When the outside air temperature is low during the heating operation, it is necessary to lower the evaporation temperature of the refrigerant in order to ensure the difference between the evaporation temperature of the refrigerant flowing through the first heat exchanger and the outside air temperature. In order to lower the evaporation temperature of the refrigerant, it is necessary to reduce the amount of refrigerant supplied to the first heat exchanger by lowering the opening of the first throttle mechanism. Therefore, when the outside air temperature is low during the heating operation, the refrigerant in the receiver is hardly supplied to the first heat exchanger due to the decrease in the opening degree of the first throttle mechanism. However, this refrigeration apparatus controls the gas injection valve to close when the outside air temperature is lower than a predetermined value during heating operation, so that the refrigerant in the receiver is sucked into the compression mechanism via the gas injection flow path. To prevent being supplied to the side. Thereby, the refrigerant | coolant in a receiver becomes easy to flow toward the 1st heat exchanger located in the downstream of a receiver. Therefore, this refrigeration apparatus can prevent the first heat exchanger from being overheated due to an abnormal decrease in the amount of refrigerant supplied from the receiver to the first heat exchanger during the heating operation.

  Therefore, the refrigeration apparatus according to the first aspect of the present invention can prevent overheating operation of the downstream heat exchanger during heating operation based on the outside air temperature.

  The refrigeration apparatus according to the second aspect of the present invention is the refrigeration apparatus according to the first aspect, further comprising a first refrigerant temperature measurement unit and a second refrigerant temperature measurement unit. The first refrigerant temperature measurement unit measures the temperature of the refrigerant flowing into the low pressure side heat exchanger. The second refrigerant temperature measurement unit measures the temperature of the refrigerant flowing downstream from the refrigerant whose temperature is measured by the first refrigerant temperature measurement unit. The low pressure side heat exchanger is a heat exchanger that is a first heat exchanger or a second heat exchanger and is located in a low pressure portion of the refrigerant circuit. The control condition is that the outside air temperature measured by the outside air temperature measuring unit is lower than the first temperature, and the refrigerant temperature measured by the first refrigerant temperature measuring unit is measured by the second refrigerant temperature measuring unit. Is lower.

  In the refrigeration apparatus, during the heating operation, the first refrigerant temperature measurement unit measures the temperature of the refrigerant flowing into the first heat exchanger, and the second refrigerant temperature measurement unit has the temperature measured by the first refrigerant temperature measurement unit. The temperature of the refrigerant flowing downstream from the measured refrigerant is measured. A 2nd refrigerant | coolant temperature measurement part measures the temperature of the refrigerant | coolant which flows through a 1st heat exchanger, for example.

  In this refrigeration apparatus, during the heating operation, the outside air temperature is lower than a predetermined first temperature, and the upstream refrigerant temperature, which is the temperature of the refrigerant flowing into the first heat exchanger, flows downstream from the refrigerant. Control is performed to close the gas injection valve when the temperature is lower than the downstream refrigerant temperature, which is the temperature of the gas. When the amount of refrigerant passing through the first heat exchanger is appropriate, the temperature of the refrigerant decreases due to pressure loss inside the first heat exchanger, so the upstream refrigerant temperature becomes higher than the downstream refrigerant temperature. However, when the refrigerant in the receiver flows to the suction side of the compression mechanism via the gas injection flow path, the amount of refrigerant passing through the first heat exchanger decreases, and the refrigerant immediately flows inside the first heat exchanger. As a result, the downstream refrigerant temperature gradually approaches the outside air temperature. If this tendency continues, the downstream refrigerant temperature becomes higher than the upstream refrigerant temperature. In the refrigeration apparatus, the refrigerant in the receiver is controlled by closing the gas injection valve when the outside air temperature is lower than the first temperature and the downstream refrigerant temperature is higher than the upstream refrigerant temperature during the heating operation. Is prevented from being supplied to the suction side of the compression mechanism via the gas injection flow path. Thereby, the refrigerant | coolant in a receiver becomes easy to flow toward the 1st heat exchanger located in the downstream of a receiver. Therefore, this refrigeration apparatus can prevent the first heat exchanger from being overheated due to an abnormal decrease in the amount of refrigerant supplied from the receiver to the first heat exchanger during the heating operation.

  Therefore, the refrigeration apparatus according to the second aspect of the present invention can prevent the overheating operation of the downstream heat exchanger during the heating operation based on the outside air temperature and the temperature of the refrigerant passing through the heat exchanger. it can.

  A refrigeration apparatus according to a third aspect of the present invention is a refrigeration apparatus including a refrigerant circuit to which a compression mechanism, a first heat exchanger, a first throttle mechanism, a receiver, a second throttle mechanism, and a second heat exchanger are sequentially connected. is there. The refrigeration apparatus includes a switching mechanism, a gas injection flow path, a gas injection valve, a control unit, a first refrigerant temperature measurement unit, and a second refrigerant temperature measurement unit. The switching mechanism switches the flow direction of the refrigerant circulating in the refrigerant circuit. 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. The control unit controls the open / closed state of the gas injection valve. The first refrigerant temperature measurement unit measures the temperature of the refrigerant flowing into the low pressure side heat exchanger. The second refrigerant temperature measurement unit measures the temperature of the refrigerant flowing downstream from the refrigerant whose temperature is measured by the first refrigerant temperature measurement unit. The low pressure side heat exchanger is a heat exchanger that is a first heat exchanger or a second heat exchanger and is located in a low pressure portion of the refrigerant circuit. The control unit closes the gas injection valve when the control condition is satisfied during the heating operation. The control condition is that the temperature of the refrigerant measured by the first refrigerant temperature measuring unit is lower than the temperature of the refrigerant measured by the second refrigerant temperature measuring unit.

  This refrigeration apparatus controls the gas injection valve to close when the downstream refrigerant temperature is higher than the upstream refrigerant temperature during heating operation, so that the refrigerant in the receiver passes through the gas injection flow path. Prevents supply to the suction side. Therefore, this refrigeration apparatus can prevent the first heat exchanger from being overheated due to an abnormal decrease in the amount of refrigerant supplied from the receiver to the first heat exchanger during the heating operation.

  Therefore, the refrigeration apparatus according to the third aspect of the present invention can prevent the overheating operation of the downstream heat exchanger during the heating operation based on the temperature of the refrigerant passing through the heat exchanger.

  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 further includes a rotation speed measurement unit. The rotation speed measurement unit measures the rotation speed of the compression mechanism. The control unit closes the gas injection valve when the control condition is satisfied during the heating operation. The control condition further includes that the rotational speed of the compression mechanism measured by the rotational speed measurement unit is lower than the first rotational speed.

  This refrigeration apparatus performs control to close the gas injection valve when the rotation speed (frequency) of the compression mechanism is lower than a predetermined first rotation speed during heating operation. When the rotation speed of the compression mechanism is low, the amount of refrigerant supplied from the receiver to the suction side of the compression mechanism via the gas injection flow path becomes excessive as compared with the capacity of the compression mechanism to compress the refrigerant. In this case, the amount of refrigerant circulating through the refrigerant circuit is not appropriate, and the performance of the refrigeration apparatus may be reduced. In the refrigeration apparatus, when the rotation speed of the compression mechanism is lower than the first rotation speed during heating operation, the refrigerant in the receiver is controlled via the gas injection flow path by performing control to close the gas injection valve. To prevent excessive supply to the suction side.

  Therefore, the refrigeration apparatus according to the fourth aspect of the present invention can suppress the performance degradation during the heating operation based on the rotation speed of the compression mechanism.

  The refrigeration apparatus according to the fifth aspect of the present invention is the refrigeration apparatus according to any one of the first aspect to the fourth aspect, and the control unit continuously satisfies the control conditions for at least the first time. If so, close the gas injection valve.

  In the refrigeration apparatus, the control unit performs control to close the gas injection valve when each of the above control conditions is satisfied continuously for a predetermined first time. When there are a plurality of control conditions, the control unit can set the first time for each control condition. This refrigeration apparatus can suppress the number of times of performing control for opening and closing the gas injection valve.

  Therefore, the refrigeration apparatus according to the fifth aspect of the present invention can suppress the deterioration of the gas injection valve.

  The refrigeration apparatus according to the first aspect can prevent the overheat operation of the downstream heat exchanger during the heating operation based on the outside air temperature.

  The refrigeration apparatus according to the second aspect can prevent the overheating operation of the downstream heat exchanger during the heating operation based on the outside air temperature and the temperature of the refrigerant passing through the heat exchanger.

  The refrigeration apparatus according to the third aspect can prevent the overheating operation of the downstream heat exchanger during the heating operation based on the temperature of the refrigerant passing through the heat exchanger.

  The refrigeration apparatus according to the fourth aspect can suppress performance degradation during heating operation based on the rotation speed of the compression mechanism.

  The refrigeration apparatus according to the fifth aspect can suppress the deterioration of the gas injection valve.

It is a block diagram of the air harmony device concerning a 1st embodiment. It is a Mollier diagram of a refrigerant showing the refrigerating cycle of an air harmony device. It is a block diagram of the air conditioning apparatus which concerns on 2nd Embodiment. It is a block diagram of an air harmony device concerning modification B.

-First embodiment-
(1) Configuration of Air Conditioner The refrigeration apparatus according to the first 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, a control device 5, and an outside air temperature measuring device 6. 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, an indoor heat exchanger 17, a gas injection pipe 18, It consists of a gas injection valve 19 and a capillary tube 21. 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, a gas injection pipe 18, a gas injection valve 19, and a capillary. The tube 21, the outdoor fan 4, the control device 5, and the outside air temperature measuring device 6 are included. 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 to become liquid refrigerant. In the heating operation mode, the outdoor heat exchanger 13 performs heat exchange between the refrigerant that has been decompressed through the first electric expansion valve 14 and outdoor air. In the heating operation mode, the refrigerant flowing in the outdoor heat exchanger 13 is heated and evaporated to become a gas refrigerant.

  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 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 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 performs heat exchange between the refrigerant that has been decompressed through the second electric expansion valve 16 and the air in the room in which the indoor unit 20 is installed. In the cooling operation mode, the 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 11 a 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 to become a liquid refrigerant, and is 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 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 shown in FIG. 1, 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.

  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 communicates with the compressor 11, the four-way switching valve 12, the first electric expansion valve 14, the second electric expansion valve 16, the gas injection valve 19, the indoor fan 3, the outdoor fan 4, the outdoor air temperature measuring device 6, and the like. A computer connected via a 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 opening degree of the gas injection valve 19, and the indoor fan 3. The rotational speed, the rotational speed of the outdoor fan 4 and the like 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. The control device 5 acquires the outside air temperature measured by the outside air temperature measuring device 6.

  The outside temperature measuring device 6 is a thermometer attached to the casing of the outdoor unit 10, for example. The outside air temperature measuring device 6 measures the outside air temperature that is the temperature of the outdoor air in which the outdoor unit 10 is installed. The outdoor temperature measuring device 6 may be a device independent from the outdoor unit 10 as long as it is a device for measuring the temperature of outdoor air.

(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. The refrigerant states at A to H shown in FIG. 2 respectively correspond to the refrigerant states in the cooling operation mode shown at A to H 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. E → H represents the evaporation process of the refrigerant. The air conditioner 1 repeats the refrigeration cycle of A-> B-> C-> D1-> D2-> E-> H-> 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.

  In FIG. 2, F represents a gas-liquid two-phase refrigerant that flows out from the receiver 15. F is located on the dry saturated vapor line L1. F → G indicates a refrigerant evaporation process in the gas injection valve 19. The refrigerant evaporated in the outdoor heat exchanger 13 or the indoor heat exchanger 17 (symbol H in FIG. 2) joins the refrigerant evaporated in the gas injection valve 19 (symbol G in FIG. 2), and the suction pipe of the compressor 11 It becomes the gas refrigerant (symbol A in FIG. 2) supplied to 11a.

(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 decompressed 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.

  In the cooling operation mode, an increase in the temperature of the compressor 11 can be suppressed by increasing the amount of the refrigerant flowing through the gas injection pipe 18 and lowering the temperature of the refrigerant sucked by the compressor 11.

(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 decompressed 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.

  In the heating operation mode, the flow rate of the refrigerant passing through the indoor heat exchanger 17 is increased as much as possible while suppressing the amount of refrigerant flowing through the gas injection pipe 18 so as not to decrease the temperature of the refrigerant sucked by the compressor 11 as much as possible. By doing so, the efficiency of heat exchange of the indoor heat exchanger 17 can be improved.

(2-3) Control of Refrigerant Circuit Before the operation of the air conditioner 1 is started, the first electric expansion valve 14, the second electric expansion valve 16, and the gas injection valve 19 are closed. At the start of the operation of the air conditioner 1, the control device 5 first fully opens the high-pressure side motor-operated valve located in the high-pressure part of the refrigerant circuit 2, and then is located in the low-pressure part of the refrigerant circuit 2. Control to fully open the low-pressure side motorized valve. 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. The control device 5 performs control to open the gas injection valve 19 after a predetermined time has elapsed after the operation of the air conditioner 1 is started and the state of the refrigerant circulating in the refrigerant circuit 2 is stabilized.

  During the operation of the air conditioner 1, the control device 5 periodically acquires the outside air temperature measured by the outside air temperature measuring device 6. The control device 5 stores a first temperature that is a predetermined temperature. The first temperature is set in advance by, for example, an administrator of the air conditioner 1. In the heating operation mode, the control device 5 periodically compares the outside air temperature and the first temperature, and when the first control condition that the outside air temperature is lower than the first temperature is satisfied, the control device 5 switches the gas injection valve 19. Close control is performed.

  The refrigerant circuit 2 is circulated until a predetermined time has elapsed since the start of the operation of the air conditioner 1 and until a predetermined time has elapsed since the start of the defrost operation of the air conditioner 1. Since the state of the refrigerant is not stable, the control for closing the gas injection valve 19 is not performed.

(3) Features The air conditioner 1 includes a receiver 15 for temporarily storing a gas-liquid two-phase refrigerant. During operation of the air conditioner 1, when the gas injection valve 19 is open, the gas refrigerant stored in the receiver 15 is injected into the suction pipe 11 a of the compressor 11 through the gas injection pipe 18.

  In the heating operation mode, the air conditioner 1 performs control to close the gas injection valve 19 when the outside air temperature measured by the outside air temperature measuring device 6 is lower than a predetermined first temperature. When the gas injection valve 19 is closed, the gas refrigerant stored in the receiver 15 is not injected into the suction pipe 11 a of the compressor 11 through the gas injection pipe 18. Thereby, the refrigerant in the receiver 15 easily flows toward the outdoor heat exchanger 13 located on the downstream side of the receiver 15.

  In the heating operation mode, the lower the outside air temperature, the smaller the difference between the refrigerant evaporation temperature in the outdoor heat exchanger 13 and the outside air temperature. Therefore, in the heating operation mode, when the outside air temperature is low, in order to secure the difference between the refrigerant evaporation temperature in the outdoor heat exchanger 13 and the outside air temperature, and to improve the heat exchange efficiency in the outdoor heat exchanger 13, It is necessary to lower the evaporation temperature of the refrigerant. In order to reduce the evaporation temperature of the refrigerant in the outdoor heat exchanger 13, it is necessary to reduce the amount of refrigerant supplied to the outdoor heat exchanger 13 by reducing the opening degree of the first electric expansion valve 14. At this time, if the gas injection valve 19 is open, a part of the refrigerant in the receiver 15 flows through the gas injection pipe 18 and is injected into the suction pipe 11a of the compressor 11, so that the refrigerant in the receiver 15 is It becomes difficult to be supplied to the outdoor heat exchanger 13.

  However, in the heating operation mode, the air conditioner 1 performs control to close the gas injection valve 19 when the outside air temperature is lower than the first temperature, so that the refrigerant in the receiver 15 flows through the gas injection pipe 18 and is compressed. The supply to the suction pipe 11a of the machine 11 is prevented. Therefore, the air conditioning apparatus 1 can prevent the outdoor heat exchanger 13 from being overheated due to an abnormal decrease in the amount of refrigerant flowing through the outdoor heat exchanger 13 in the heating operation mode.

  Therefore, the air conditioning apparatus 1 according to the present embodiment can prevent the overheating operation of the outdoor heat exchanger 13 in the heating operation mode based on the outside air temperature.

-Second embodiment-
A refrigeration apparatus according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 3 is a block diagram of an air conditioner 101 that is a refrigeration apparatus according to the present embodiment. In FIG. 3, the same reference numerals as those shown in FIG. 1 are given to the components common to the air conditioner 1 of the first embodiment. Hereinafter, differences between the air conditioner 101 and the air conditioner 1 of the first embodiment will be mainly described.

  The air conditioning apparatus 101 is an apparatus that performs a cooling operation and a heating operation by using a chlorofluorocarbon refrigerant such as R410A and R32 as a refrigerant. The air conditioner 101 mainly includes a refrigerant circuit 2, an indoor fan 3, an outdoor fan 4, a control device 5, a first refrigerant temperature measuring device 7, and a second refrigerant temperature measuring device 8. 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, an indoor heat exchanger 17, a gas injection pipe 18, And a gas injection valve 19. 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, a gas injection pipe 18, a gas injection valve 19, and an outdoor unit. The fan 4, the control device 5, the first refrigerant temperature measuring device 7, and the second refrigerant temperature measuring device 8 are included. The indoor unit 20 mainly includes the indoor heat exchanger 17 and the indoor fan 3. As shown in FIG. 3, the outdoor unit 10 is connected to the indoor unit 20 via a first communication pipe 31 and a second communication pipe 32. The compressor 11 is connected to a suction pipe 11a and a discharge pipe 11b that are part of the refrigerant pipe. The operation of the air conditioner 101 in the cooling operation mode and the heating operation mode is the same as the operation of the air conditioner 1 of the first embodiment.

  The first refrigerant temperature measuring device 7 measures the temperature of the refrigerant flowing into the outdoor heat exchanger 13. The 1st refrigerant | coolant temperature measuring apparatus 7 is attached to the outer periphery of the refrigerant | coolant piping connected to the outdoor heat exchanger 13, for example.

  The second refrigerant temperature measuring device 8 measures the temperature of the refrigerant flowing downstream from the refrigerant whose temperature is measured by the first refrigerant temperature measuring device 7. In this embodiment, the 2nd refrigerant | coolant temperature measuring apparatus 8 measures the temperature of the refrigerant | coolant which flows through the upstream of the refrigerant | coolant flow path in the outdoor heat exchanger 13, as FIG. 3 shows. The 2nd refrigerant | coolant temperature measuring apparatus 8 is attached to the outer periphery of the heat exchange part of the outdoor heat exchanger 13, for example.

  The control device 5 includes a compressor 11, a four-way switching valve 12, a first electric expansion valve 14, a second electric expansion valve 16, a gas injection valve 19, an indoor fan 3, an outdoor fan 4, a first refrigerant temperature measuring device 7, and The computer is connected to the second refrigerant temperature measuring device 8 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 opening degree of the gas injection valve 19, and the indoor fan 3. The rotational speed, the rotational speed of the outdoor fan 4 and the like 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. The control device 5 obtains the first refrigerant temperature that is the refrigerant temperature measured by the first refrigerant temperature measurement device 7 and the second refrigerant temperature that is the refrigerant temperature measured by the second refrigerant temperature measurement device 8. To do.

  During the operation of the air conditioner 101, the control device 5 periodically determines the first refrigerant temperature measured by the first refrigerant temperature measurement device 7 and the second refrigerant temperature measured by the second refrigerant temperature measurement device 8. To get to. In the heating operation mode, the control device 5 periodically compares the first refrigerant temperature and the second refrigerant temperature, and when the second control condition that the first refrigerant temperature is lower than the second refrigerant temperature is satisfied. The gas injection valve 19 is controlled to be closed.

  In the air conditioner 101, in the heating operation mode, when the amount of refrigerant passing through the outdoor heat exchanger 13 is appropriate, the temperature of the refrigerant decreases due to pressure loss inside the outdoor heat exchanger 13, so the first refrigerant The temperature is higher than the second refrigerant temperature. However, if the refrigerant in the receiver 15 excessively flows into the suction pipe 11a of the compressor 11 via the gas injection pipe 18, the amount of refrigerant supplied to the outdoor heat exchanger 13 decreases, and the outdoor heat exchanger 13 Since the refrigerant evaporates immediately inside the second refrigerant temperature, the second refrigerant temperature gradually approaches the outside air temperature. If this tendency continues, the first refrigerant temperature will eventually become lower than the second refrigerant temperature. In the heating operation mode, the air conditioner 101 performs control to close the gas injection valve 19 when the first refrigerant temperature is lower than the second refrigerant temperature, so that the refrigerant in the receiver 15 passes through the gas injection pipe 18. The flow to the suction pipe 11a of the compressor 11 is prevented. Therefore, in the air conditioning apparatus 101, in the heating operation mode, it is possible to prevent the amount of refrigerant flowing through the outdoor heat exchanger 13 from being abnormally reduced and the outdoor heat exchanger 13 from being overheated.

  Therefore, the air conditioning apparatus 101 according to the present embodiment can prevent the overheating operation of the outdoor heat exchanger 13 in the heating operation mode based on the temperature of the refrigerant passing through the outdoor heat exchanger 13.

  Note that the second control condition may be another control condition based on the first refrigerant temperature and the second refrigerant temperature, depending on the type of refrigerant, the mounting position of the second refrigerant temperature measuring device 8, and the like. Specifically, when the value obtained by adding a predetermined temperature to the first refrigerant temperature is lower than the second refrigerant temperature, the control unit 5 may determine that the second control condition is satisfied.

-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.

(1) Modification A
In the air conditioner 1 of the first embodiment, the control device 5 performs control to close the gas injection valve 19 when the first control condition that the outside air temperature is lower than the first temperature is satisfied in the heating operation mode. . In the air conditioner 101 of the second embodiment, the control device 5 closes the gas injection valve 19 when the second control condition that the first refrigerant temperature is lower than the second refrigerant temperature is satisfied in the heating operation mode. Take control.

  However, the control device 5 of the air conditioner 1 may perform control to close the gas injection valve 19 when both the first control condition and the second control condition are satisfied. In this case, the air conditioning apparatus 1 includes an outside air temperature measuring device 6, a first refrigerant temperature measuring device 7, and a second refrigerant temperature measuring device 8.

  Note that the control device 5 of the air conditioner 1 may perform control to close the gas injection valve 19 when one of the first control condition and the second control condition is satisfied.

(2) Modification B
The control device 5 of the air conditioner 1 of the first embodiment further satisfies the third control condition that the first control condition is satisfied and that the rotation speed (frequency) of the compressor 11 is lower than the first rotation speed. In such a case, the gas injection valve 19 may be closed. In this case, the air conditioner 1 further includes a rotation speed measurement unit 9 that measures the rotation speed of the compressor 11. As the first rotation speed, for example, the value of the reference frequency of the compressor 11 in the heating operation mode is used.

  FIG. 4 is a block diagram of an air conditioner 201 that is a refrigeration apparatus according to this modification. In FIG. 4, the same reference numerals as those shown in FIG. 1 are given to the components common to the air conditioner 1 of the first embodiment. As shown in FIG. 4, a rotation speed measuring unit 9 is attached to the compressor 11. The control device 5 is connected to the rotational speed measurement unit 9 via a communication line, and acquires the current rotational speed of the compressor 11 measured by the rotational speed measurement unit 9.

  In the air conditioning apparatus 201, in the heating operation mode, when the rotation speed of the compressor 11 is lower than a predetermined first rotation speed, control is performed to close the gas injection valve 19. When the rotation speed of the compressor 11 is low, the amount of refrigerant supplied from the receiver 15 to the suction pipe 11a of the compressor 11 via the gas injection flow path 18 is excessive compared to the compressor 11's ability to compress the refrigerant. become. In this case, the amount of refrigerant circulating through the refrigerant circuit 2 is not appropriate, and the performance of the air conditioner 201 may be degraded. The air conditioner 201 performs control to close the gas injection valve 19 when the third control condition is satisfied in the heating operation mode, so that the refrigerant in the receiver 15 passes through the gas injection flow path 18 and the compressor 11. The excessive supply to the suction pipe 11a is prevented. Therefore, the air conditioning apparatus 201 can suppress performance degradation in the heating operation mode based on the rotation speed of the compressor 11.

  Moreover, the air conditioning apparatus 101 of the second embodiment may further include a rotation speed measurement unit 9. In this case, the control device 5 may perform control to close the gas injection valve 19 when both the second control condition and the third control condition are satisfied.

  In addition, the air conditioner 1 of Modification A may further include a rotation speed measurement unit 9. In this case, the control device 5 may perform control to close the gas injection valve 19 when all of the first control condition, the second control condition, and the third control condition are satisfied.

  Further, the air conditioning apparatus 201 of the present modification may perform control to close the gas injection valve 19 when only the third control condition is satisfied.

(3) Modification C
The control device 5 of the air conditioner 1 of the first embodiment may perform control to close the gas injection valve 19 when the first control condition is continuously satisfied for at least a predetermined time. For example, the control device 5 may perform control to close the gas injection valve 19 when a state in which the outside air temperature is lower than the first temperature continues continuously for a predetermined time.

  Further, the control device 5 of the air conditioner 101 of the second embodiment may perform control to close the gas injection valve 19 when the second control condition is continuously satisfied for at least a predetermined time. For example, the control device 5 may perform control to close the gas injection valve 19 when a state in which the first refrigerant temperature is lower than the second refrigerant temperature continues continuously for a predetermined time.

  Further, the control device 5 of the air conditioner 201 of the modified example B is configured so that the gas injection valve 19 is satisfied when the first control condition is satisfied and the third control condition is continuously satisfied for at least a predetermined time. You may control to close. For example, the control device 5 determines the gas injection valve when the state in which the outside air temperature is lower than the first temperature and the state in which the rotational speed of the compressor 11 is lower than the first rotational speed continue continuously for a predetermined time. Control to close 19 may be performed.

  In addition, the control apparatus 5 of each air conditioning apparatus as described in the modified examples A and B closes the gas injection valve 19 based on at least two of the first control condition, the second control condition, and the third control condition. Control is in progress. In this case, a predetermined time to be satisfied at least continuously may be set for each control condition. For example, the control device 5 of the air conditioner 1 of the modified example A is configured such that when the first control condition is satisfied continuously for a predetermined time and the second control condition is satisfied continuously for a predetermined time, the gas Control to close the injection valve 19 may be performed. In addition, the control device 5 of the air conditioner 201 of the modified example B is configured so that the first control condition is satisfied continuously for a predetermined time and the third control condition is satisfied continuously for a predetermined time. Control to close the injection valve 19 may be performed.

(4) Modification D
In the present embodiment and the modifications A to C, the control device 5 performs control to close the gas injection valve 19 when a predetermined condition is satisfied, and prevents the outdoor heat exchanger 13 from being overheated. . However, in a state where the gas injection valve 19 is closed, the control device 5 may further perform control to open the gas injection valve 19 when a predetermined condition is satisfied. By opening the gas injection valve 19 and supplying the refrigerant in the receiver 15 to the suction pipe 11 a of the compressor 11, the temperature of the refrigerant sucked into the compressor 11 is lowered and the temperature rise of the compressor 11 is suppressed. be able to. Thereby, the compression efficiency of the compressor 11 can be improved.

  As a specific example of the first embodiment, the control device 5 may further perform control to open the gas injection valve 19 when a fourth control condition that the outside air temperature is equal to or higher than the second temperature is satisfied. The second temperature under the fourth control condition is preferably higher than the first temperature under the first control condition. For example, the control device 5 closes the gas injection valve 19 when the outside air temperature falls below a predetermined first temperature, and then gas when the outside air temperature rises to a predetermined second temperature higher than the first temperature. Open the injection valve 19. By setting the second temperature to a value higher than the first temperature, chattering of the gas injection valve 19 is prevented. Moreover, the control apparatus 5 may adjust the opening degree of the gas injection valve 19 according to the difference of external temperature and 2nd temperature. For example, the control device 5 may increase the opening of the gas injection valve 19 as the difference between the outside air temperature and the second temperature increases.

  As a specific example related to the second embodiment, the control device 5 may further perform control for opening the gas injection valve 19 when the fifth control condition that the first refrigerant temperature is equal to or higher than the second refrigerant temperature is satisfied. Good. When the fifth control condition is satisfied, the first refrigerant temperature is preferably higher than the first refrigerant temperature when the second control condition is satisfied. For example, the control device 5 closes the gas injection valve 19 when the first refrigerant temperature is less than 3 ° C. lower than the second refrigerant temperature, and then the first refrigerant temperature rises to the second refrigerant temperature. Open the gas injection valve 19. By setting the second control condition and the fifth control condition in this way, chattering of the gas injection valve 19 is prevented. Moreover, the control apparatus 5 may adjust the opening degree of the gas injection valve 19 according to the difference of 1st refrigerant | coolant temperature and 2nd refrigerant | coolant temperature. For example, the control device 5 may increase the opening of the gas injection valve 19 as the difference between the first refrigerant temperature and the second refrigerant temperature increases.

  As a specific example related to the modified example B, the control device 5 may further perform control to open the gas injection valve 19 when the sixth control condition that the rotational speed of the compressor 11 is equal to or higher than the second rotational speed is satisfied. . The second rotational speed of the sixth control condition is preferably higher than the first rotational speed of the third control condition. For example, the control device 5 closes the gas injection valve 19 when the frequency of the compressor 11 becomes 0 Hz (first rotation speed), and then the frequency of the compressor 11 reaches a predetermined value (second rotation speed). When rising, the gas injection valve 19 is opened. By setting the second rotational speed to a value higher than the first rotational speed, chattering of the gas injection valve 19 is prevented. Moreover, the control apparatus 5 may adjust the opening degree of the gas injection valve 19 according to the difference of the present rotation speed of the compressor 11, and 2nd rotation speed. For example, the control device 5 may increase the opening of the gas injection valve 19 as the difference between the current rotation speed of the compressor 11 and the second rotation speed is larger.

  The refrigeration apparatus according to the present invention can prevent the overheating operation of the downstream heat exchanger during the heating operation.

1 Air conditioning equipment (refrigeration equipment)
2 Refrigerant circuit 5 Control device (control unit)
6 Outside temperature measuring device (outside temperature measuring unit)
7 First refrigerant temperature measuring device (first refrigerant temperature measuring unit)
8 Second refrigerant temperature measuring device (second refrigerant temperature measuring unit)
9 Rotational speed measuring device (Rotational speed measuring 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 throttle mechanism)
15 Receiver 16 Second electric expansion valve (second throttle mechanism)
17 Indoor heat exchanger (second heat exchanger)
18 Gas injection pipe (gas injection flow path)
19 Gas injection valve 101 Air conditioner (refrigeration equipment)

JP 2006-200890 A

Claims (5)

A refrigerant in which the compression mechanism (11), the first heat exchanger (13), the first throttle mechanism (14), the receiver (15), the second throttle mechanism (16), and the second heat exchanger (17) are sequentially connected. A refrigeration apparatus comprising a circuit (2),
A switching mechanism (12) for switching the flow direction of the refrigerant circulating in the refrigerant circuit;
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;
A control unit (5) for controlling the open / closed state of the gas injection valve;
An outside air temperature measurement unit (6) for measuring the outside air temperature;
With
The control unit closes the gas injection valve when a control condition is satisfied during heating operation,
The control condition is that the outside air temperature measured by the outside air temperature measuring unit is lower than a first temperature.
Refrigeration equipment (1). Regarding the low-pressure side heat exchanger that is the first heat exchanger or the second heat exchanger and is a heat exchanger located in the low-pressure part of the refrigerant circuit, the refrigerant flowing into the low-pressure side heat exchanger A first refrigerant temperature measuring unit (7) for measuring temperature;
A second refrigerant temperature measuring section (8) for measuring the temperature of the refrigerant flowing downstream from the refrigerant whose temperature is measured by the first refrigerant temperature measuring section;
Further comprising
The control condition is that the outside air temperature measured by the outside air temperature measuring unit is lower than the first temperature, and the refrigerant temperature measured by the first refrigerant temperature measuring unit is measured by the second refrigerant temperature measuring unit. Lower than the temperature of the cooled refrigerant,
The refrigeration apparatus according to claim 1. A refrigerant in which the compression mechanism (11), the first heat exchanger (13), the first throttle mechanism (14), the receiver (15), the second throttle mechanism (16), and the second heat exchanger (17) are sequentially connected. A refrigeration apparatus comprising a circuit (2),
A switching mechanism (12) for switching the flow direction of the refrigerant circulating in the refrigerant circuit;
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;
A control unit (5) for controlling the open / closed state of the gas injection valve;
Regarding the low-pressure side heat exchanger that is the first heat exchanger or the second heat exchanger and is a heat exchanger located in the low-pressure part of the refrigerant circuit, the refrigerant flowing into the low-pressure side heat exchanger A first refrigerant temperature measuring unit (7) for measuring temperature;
A second refrigerant temperature measuring section (8) for measuring the temperature of the refrigerant flowing downstream from the refrigerant whose temperature is measured by the first refrigerant temperature measuring section;
With
The control unit closes the gas injection valve when a control condition is satisfied during heating operation,
The control condition is that the temperature of the refrigerant measured by the first refrigerant temperature measurement unit is lower than the temperature of the refrigerant measured by the second refrigerant temperature measurement unit.
Refrigeration equipment (101). A rotation speed measurement unit (9) for measuring the rotation speed of the compression mechanism;
The control condition further includes that the rotational speed of the compression mechanism measured by the rotational speed measurement unit is lower than the first rotational speed.
The refrigeration apparatus according to any one of claims 1 to 3. The control unit closes the gas injection valve when the control condition is continuously satisfied for at least a first time.
The refrigeration apparatus according to any one of claims 1 to 4.

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