JP2015197255A - Refrigeration cycle device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a refrigeration cycle device capable of suppressing deterioration of heating capacity of a heating object fluid caused by frost formation in an evaporator without causing increase in noise.SOLUTION: When it is determined that frost has been formed in an outdoor heat exchanger 14, which is an evaporator, a throttle opening of an electric type expansion valve 13, which is decompression means, is increased so as to become a target throttle opening stored in target value storage means 40c of a control device 40, and refrigerant discharge capacity (rotational frequency) of a compressor 11 is increased so as to become a target refrigerant discharge capacity stored in the target value storage means 40c. Thereby, while suppressing frost formation in the outdoor heat exchanger 14 by increasing refrigerant evaporation temperature in the outdoor heat exchanger 14, deterioration of heating capacity for hot water for supply, which is a heating object fluid, is suppressed.

Description

  The present invention relates to a vapor compression refrigeration cycle apparatus.

  Conventionally, Patent Document 1 discloses a vapor compression refrigeration cycle apparatus that is applied to a heat pump type hot water heater and heats hot water as a fluid to be heated.

  This type of refrigeration cycle apparatus includes an outdoor heat exchanger (evaporator) that evaporates the low-pressure refrigerant by exchanging heat between the low-pressure refrigerant and the outside air. When operated at low outdoor temperature and high humidity conditions, There is a risk of frost formation on the outdoor heat exchanger. When such frost formation occurs, the outdoor air passage of the outdoor heat exchanger is blocked by frost, so the amount of heat absorbed by the refrigerant in the outdoor heat exchanger is reduced, and the heating capacity of the hot water in the refrigeration cycle apparatus is increased. It will decline.

  In contrast, in the refrigeration cycle apparatus of Patent Document 1, when the temperature of the outdoor heat exchanger becomes equal to or lower than a predetermined reference temperature, the rotational speed of the blower that blows outside air toward the outdoor heat exchanger (air blowing) Ability). As a result, the amount of heat absorbed by the refrigerant in the outdoor heat exchanger is increased to prevent frost formation on the outdoor heat exchanger, and the heating capacity of hot water (heating target fluid) of the refrigeration cycle apparatus is reduced. Is suppressed.

JP 2008-39289 A

  However, like the refrigeration cycle apparatus of Patent Document 1, when the temperature of the outdoor heat exchanger becomes equal to or lower than the reference temperature, if the rotational speed of the blower is increased, frost formation occurs in the outdoor heat exchanger. However, the operating noise (noise) of the blower increases, and this operating noise may be annoying to the user.

  An object of this invention is to provide the refrigerating-cycle apparatus which can suppress the fall of the heating capability of the heating target fluid by the frost formation of an evaporator, without causing the increase in noise in view of the said point.

The present invention has been devised in order to achieve the above object. In the invention according to claim 1, the compressor (11) compresses and discharges the refrigerant, and the compressor (11) discharges the refrigerant. A heat radiator (12) that heats the fluid to be heated by exchanging heat between the high-pressure refrigerant and the fluid to be heated, a decompression means (13) that decompresses the refrigerant flowing out of the radiator (12), and a decompression means (13) An evaporator (14) for evaporating the low-pressure refrigerant by exchanging heat between the decompressed low-pressure refrigerant and the outside air, a discharge capacity control means (40a) for controlling the refrigerant discharge capacity of the compressor (11), and a decompression means ( 13) throttle opening control means (40b) for controlling the throttle opening, and frost determination means (S11) for determining whether or not frost is generated in the evaporator (14),
When the frost formation determination means (S11) determines that frost formation has occurred in the evaporator (14), the discharge capacity control means (40a) increases the refrigerant discharge capacity and the throttle opening degree control means (40b). Is characterized by a refrigeration cycle device that increases the throttle opening of the decompression means (13).

  According to this, when the frosting determination means (S11) determines that frost formation has occurred in the evaporator (14), the throttle opening degree control means (40b) determines the throttle opening degree of the pressure reduction means (13). Therefore, the pressure of the low-pressure refrigerant flowing into the evaporator (14) can be increased, and the refrigerant evaporation temperature in the evaporator (14) can be increased. Therefore, it can suppress that frost formation arises in an evaporator (14) or frost formation of an evaporator (14) advances.

  Further, when the frost determination means (S11) determines that frost is generated in the evaporator (14), the discharge capacity control means (40a) increases the refrigerant discharge capacity. The flow rate of the circulating refrigerant can be increased. Therefore, even if the refrigerant evaporation temperature in the evaporator (14) is increased and the heat absorption amount of the low-pressure refrigerant in the evaporator (14) is decreased, the heating capacity of the heating target fluid of the refrigeration cycle apparatus is decreased. This can be suppressed.

  In other words, according to the invention described in this claim, a refrigeration cycle apparatus capable of suppressing a decrease in the heating capacity of the fluid to be heated due to frost formation of the evaporator (14) without causing an increase in noise as in the prior art. Can be provided.

  Here, the heating capability of the fluid to be heated of the refrigeration cycle apparatus in the present claims is the heating capability of the fluid to be heated in the radiator (12). Therefore, the heating capacity of the fluid to be heated includes the enthalpy difference obtained by subtracting the enthalpy of the radiator (12) outlet side refrigerant from the enthalpy of the radiator (12) inlet side refrigerant, and the flow rate of the high-pressure refrigerant flowing through the radiator (12). It can be defined using a value obtained by integrating (mass flow rate).

  Further, the frosting determination means (S11) in this claim is not limited to the determination means for determining whether or not frost formation has actually occurred in the evaporator (14), and the frosting determination means (S11) is attached to the evaporator (14). It is determined whether or not the operating conditions can cause frost, and when it is determined that the operating conditions can cause frost formation in the evaporator (14), it is determined that frost formation has occurred in the evaporator (14). It is determined whether there is a possibility that frost formation has occurred in the determination means or the evaporator (14), and when it is determined that frost formation may have occurred in the evaporator (14), the evaporator (14) includes determination means for determining that frost formation has occurred.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a whole lineblock diagram of the heat pump type hot water heater of a 1st embodiment. It is a flowchart which shows the principal part of the control processing of the heat pump type water heater of 1st Embodiment. It is a control characteristic figure for determining the target refrigerant discharge capacity of the compressor of the heat pump type hot water supply machine of a 1st embodiment, and the target throttle opening of an electric expansion valve. It is a control characteristic diagram for determining the range of the target refrigerant | coolant discharge capability of the compressor of the heat pump type water heater of 2nd Embodiment, and the range of the target throttle opening degree of an electric expansion valve. It is a flowchart which shows the principal part of the control processing of the heat pump type water heater of 3rd Embodiment. It is a control characteristic diagram for determining the target refrigerant | coolant discharge capability of the compressor of the heat pump type water heater of 3rd Embodiment, and the target throttle opening degree of an electric expansion valve.

(First embodiment)
1st Embodiment of this invention is described using FIGS. 1-3. In the present embodiment, a refrigeration cycle apparatus (heat pump cycle) 10 according to the present invention is applied to a heat pump type hot water heater 1. Furthermore, the heat pump type hot water heater 1 includes a hot water storage tank 20, a water circulation circuit 30 and the like in addition to the refrigeration cycle apparatus 10, as shown in the overall configuration diagram of FIG.

  The refrigeration cycle apparatus 10 fulfills a function of heating hot water as a fluid to be heated in the heat pump hot water heater 1. The hot water storage tank 20 is hot water storage means for storing hot water heated by the refrigeration cycle apparatus 10. Further, the water circulation circuit 30 is a water circuit that circulates hot water between the water-refrigerant heat exchanger 12 and the hot water storage tank 20 of the refrigeration cycle apparatus 10.

  More specifically, the refrigeration cycle apparatus 10 is configured by sequentially connecting a compressor 11, a water-refrigerant heat exchanger 12, an electric expansion valve 13, and an outdoor heat exchanger 14 by piping.

  Further, in the refrigeration cycle apparatus 10 of the present embodiment, carbon dioxide is adopted as the refrigerant, and the high-pressure side refrigerant pressure in the cycle from the discharge port side of the compressor 11 to the inlet side of the electric expansion valve 13 is the criticality of the refrigerant. It constitutes a supercritical refrigeration cycle that exceeds the pressure. This refrigerant is mixed with refrigerating machine oil for lubricating the compressor 11, and a part of the refrigerating machine oil circulates in the cycle together with the refrigerant.

  The compressor 11 sucks refrigerant in the refrigeration cycle apparatus 10 and compresses and discharges the refrigerant until the pressure becomes equal to or higher than the critical pressure. The electric compressor drives a fixed capacity type compression mechanism with a fixed discharge capacity by an electric motor. It is. Specifically, various compression mechanisms such as a scroll type compression mechanism and a vane type compression mechanism can be adopted as the fixed capacity type compression mechanism.

  The electric motor has its rotational speed controlled by a control signal output from the control device 40 to be described later, and may employ either an AC motor or a DC motor. And the refrigerant | coolant discharge capability of the compressor 11 is changed by this rotation speed control. Therefore, the electric motor of the present embodiment constitutes the discharge capacity changing means of the compressor 11.

  A refrigerant passage 12 a inlet side of the water-refrigerant heat exchanger 12 is connected to the discharge port of the compressor 11. The water-refrigerant heat exchanger 12 has a refrigerant passage 12a for circulating the high-pressure refrigerant discharged from the compressor 11, and a water passage 12b for circulating hot water circulating through the water circulation circuit 30, and circulates through the refrigerant passage 12a. It is a radiator that heats the hot water by exchanging heat between the high-pressure refrigerant and the hot water flowing through the water passage 12b.

  As a specific configuration of such a water-refrigerant heat exchanger 12, a configuration in which a water passage 12b is arranged on the outer periphery of the refrigerant passage 12a to exchange heat between the refrigerant and the cooling water, or a meandering passage through which refrigerant flows as the refrigerant passage 12a. Or a plurality of tubes, a water passage 12b is formed between adjacent tubes, and a corrugated fin or a plate fin that promotes heat exchange between the refrigerant and the cooling water is used. May be.

  Further, in the present embodiment, the water-refrigerant heat exchanger 12 is a counter flow type heat exchanger in which the flow direction of the refrigerant flowing through the refrigerant passage 12a and the flow direction of hot water flowing through the water passage 12b are counterflows. Is adopted.

  In such a counter-flow heat exchanger, heat is exchanged between the refrigerant on the refrigerant passage 12a inlet side and the hot water on the water passage 12b outlet side, and the refrigerant on the refrigerant passage 12a outlet side and the hot water on the water passage 12b inlet side. Therefore, it is possible to secure a temperature difference between the hot water and the refrigerant over the entire heat exchange region and improve the heat exchange efficiency.

  In addition, since the refrigeration cycle apparatus 10 of the present embodiment constitutes a supercritical refrigeration cycle as described above, the refrigerant is not condensed in the refrigerant passage 12a of the water-refrigerant heat exchanger 12 in a supercritical state. Dissipate heat.

  The inlet side of the electric expansion valve 13 is connected to the outlet side of the refrigerant passage 12 a of the water-refrigerant heat exchanger 12. The electric expansion valve 13 is a decompression unit that decompresses the refrigerant flowing out of the refrigerant passage 12a.

  More specifically, the electric expansion valve 13 is configured by a variable throttle mechanism having a valve body that can change the throttle opening degree and an electric actuator that changes the throttle opening degree of the valve body. The operation of the electric actuator is controlled by a control signal output from the control device 40.

  The refrigerant inlet side of the outdoor heat exchanger 14 is connected to the outlet side of the electric expansion valve 13. The outdoor heat exchanger 14 evaporates the low-pressure refrigerant and exhibits an endothermic effect by exchanging heat between the low-pressure refrigerant decompressed by the electric expansion valve 13 and the outside air (outdoor air) blown by the blower fan 14a. This is an evaporator. The blower fan 14 a is an outside air blower whose rotation speed (amount of blown air) is controlled by a control voltage output from the control device 40.

  The refrigerant outlet of the outdoor heat exchanger 14 is connected to the suction port side of the compressor 11. In addition, the gas-liquid of the refrigerant | coolant which flowed out from the outdoor heat exchanger 14 is isolate | separated into the refrigerant path from the refrigerant | coolant exit side of the outdoor heat exchanger 14 to the suction inlet side of the compressor 11, and the isolate | separated gaseous-phase refrigerant | coolant is compressor. 11 and an accumulator that stores the separated liquid-phase refrigerant as an excess refrigerant.

  In addition, each component apparatus 11-14 of the refrigerating-cycle apparatus 10 enclosed with the broken line of FIG. 1, the ventilation fan 14a, etc. are accommodated in one housing | casing, and are comprised integrally as the heat pump unit 100. FIG. Furthermore, the heat pump unit 100 is disposed outdoors.

  The hot water storage tank 20 is formed of a metal having excellent corrosion resistance (for example, stainless steel), and has a heat insulating structure in which the outer periphery is covered with a heat insulating material or a vacuum heat insulating structure with a double tank, and keeps hot hot water hot for a long time. It is a hot water tank that can. Moreover, the hot water storage tank 20 of this embodiment is formed in the hollow cylinder shape, and is formed in the vertically long shape where an axial direction extends in a substantially vertical direction.

  Connected to the upper side of the hot water storage tank 20 are an outflow pipe 21 through which hot water stored in the hot water storage tank 20 flows out and a high temperature side water pipe 32 constituting the water circulation circuit 30. On the other hand, on the lower side of the hot water storage tank 20, a water supply pipe 22 into which tap water is introduced and a low temperature side water pipe 31 constituting the water circulation circuit 30 are connected.

  A temperature control valve (not shown) is connected to the outlet side of the outflow pipe 21. And by this temperature control valve, the hot water supply water which flowed out of the hot water storage tank 20 and the low temperature tap water are mixed, and the hot water supply water adjusted to the target hot water temperature is arranged in a kitchen, a bathroom, etc. Hot water is discharged from hot water supply terminals such as taps and showers.

  Note that the hot water storage tank 20, a part of the outflow pipe 21, a part of the water supply pipe 22, and the like surrounded by the one-dot chain line in FIG. 1 are housed in one housing and integrally configured as a tank unit 200. ing. Further, the tank unit 200 is disposed outside the room, similarly to the heat pump unit 100.

  The water circulation circuit 30 includes a low temperature side water pipe 31 and a high temperature side water pipe 32. The low temperature side water pipe 31 is a low temperature side water passage that guides the low temperature hot water flowing out of the hot water storage tank 20 to the water passage 12 b inlet side of the water-refrigerant heat exchanger 12. The high temperature side water pipe 32 is a high temperature side water passage that guides hot hot water flowing out from the outlet side of the water passage 12b of the water-refrigerant heat exchanger 12 to the hot water storage tank 20 side.

  A water circulation pump 34 is disposed in the low temperature side water pipe 31. The water circulation pump 34 is water pressure feeding means that sucks hot water flowing out from the lower side of the hot water storage tank 20 and pumps it to the water passage 12b side of the water-refrigerant heat exchanger 12. The rotation speed (water pressure feeding capacity) of the water circulation pump 34 is controlled by a control voltage output from the control device 40.

  When the control device 40 operates the water circulation pump 34, the hot water flowing out from the lower side of the hot water storage tank 20 is converted into the low temperature side water pipe 31 → the water circulation pump 34 → the water passage 12 b of the water-refrigerant heat exchanger 12 → high temperature. It flows in the order of the side water piping 32 and flows into the upper side of the hot water storage tank 20. In the present embodiment, the water circulation pump 34 disposed in the water circulation circuit 30 is accommodated in the housing of the heat pump unit 100 as indicated by a broken line in FIG.

  Next, an outline of the electric control unit of the present embodiment will be described. The control device 40 is composed of a well-known microcomputer including a CPU, a ROM, a RAM and the like and its peripheral circuits. Then, various calculations and processes are performed based on the control program stored in the ROM, and the operation of various control target devices connected to the output side is controlled.

  Various control target devices such as an electric motor of the compressor 11, an electric actuator of the electric expansion valve 13, a blower fan 14 a, and a water circulation pump 34 are connected to the output side of the control device 40.

  On the other hand, a tank internal temperature sensor 41, an incoming water temperature sensor 42, a boiling temperature sensor 43, an evaporator temperature sensor 44, an outside air temperature sensor 45, a high pressure side pressure sensor 46, and the like are connected to the input side of the control device 40. The detection signals of the sensor groups are input to the control device 40.

  The tank internal temperature sensor 41 is a tank internal temperature detection means for detecting the temperature of hot water stored in the hot water storage tank 20. More specifically, the in-tank temperature sensor 41 of the present embodiment is composed of a plurality of (in this embodiment, five) temperature sensors arranged in the vertical direction in the hot water storage tank 20. Thereby, in the control apparatus 40, the temperature of the hot water supply according to the water level in the hot water storage tank 20, and the temperature distribution in the hot water storage tank 20 can be detected by the output signals of the plurality of tank internal temperature sensors 41.

  The incoming water temperature sensor 42 is an incoming water temperature detecting means for detecting an incoming water temperature Twi which is a hot water supply water temperature on the inlet side of the water passage 12 b of the water-refrigerant heat exchanger 12.

  The boiling temperature sensor 43 is a boiling temperature detection means for detecting a boiling temperature Two which is the temperature of hot water supply water on the outlet side of the water passage 12b.

  The evaporator temperature sensor 44 is an evaporator temperature detection unit that detects an evaporator temperature Te that is the temperature of the outdoor heat exchanger 14 (corresponding to the refrigerant evaporation temperature in the outdoor heat exchanger 14). More specifically, the evaporator temperature sensor 44 of the present embodiment detects the refrigerant temperature in the outdoor heat exchanger 14. Of course, as the evaporator temperature detecting means, a temperature detecting means for detecting the heat exchange fin temperature of the outdoor heat exchanger 14 may be adopted, or a temperature detecting means for detecting the temperature of other parts of the outdoor heat exchanger 14. May be adopted.

  The outside air temperature sensor 45 is an outside air temperature detecting unit that detects an outside air temperature Tam that is the temperature of the outside air that exchanges heat with the low-pressure refrigerant in the outdoor heat exchanger 14.

  The high pressure side pressure sensor 46 is high pressure side pressure detection means for detecting the high pressure side refrigerant pressure Pd of the cycle discharged from the discharge port side of the compressor 11 to the inlet side of the electric expansion valve 13. In FIG. 1, for the sake of clarity, the high pressure side pressure sensor 46 is connected to the refrigerant in the refrigerant passage from the outlet side of the refrigerant passage 12 a of the water-refrigerant heat exchanger 12 to the inlet side of the electric expansion valve 13. Although an example is shown in which the pressure is detected, the refrigerant pressure in the refrigerant passage from the discharge port side of the compressor 11 to the inlet side of the refrigerant passage 12a may be detected.

  Further, a remote controller (operation panel) 50 disposed in the room is connected to the input side of the control device 40. The remote controller 50 includes an operation switch for outputting an operation request signal for requesting the operation of the heat pump type hot water heater 1 and a stop request signal for requesting a stop, and the temperature of hot water discharged from each hot water supply terminal (target hot water temperature). Temperature setting switches for setting are provided, and operation signals of these switches are input to the control device 40.

  Note that the control device 40 of the present embodiment is configured integrally with control means for controlling various control target devices connected to the output side of the control device 40. The configuration (hardware and software) for controlling the operation constitutes a control means for controlling the operation of each control target device.

  For example, in the control device 40, the configuration for controlling the refrigerant discharge capacity (rotation speed) of the compressor 11 constitutes the discharge capacity control means 40 a and the configuration for controlling the throttle opening of the electric expansion valve 13. The aperture opening control means 40b is configured. Further, among the storage circuits of the control device 40, a circuit that stores a target refrigerant discharge capacity and a target throttle opening degree, which will be described later, constitutes a target value storage means 40c.

  Further, the discharge capacity control means 40a, the throttle opening degree control means 40b, and the like may be configured by another device with respect to the control device 40, or the control for controlling the operation of the components of the refrigeration cycle device 10 in the control device 40. You may comprise an apparatus with another apparatus with respect to the control apparatus 40 as a heat pump side control apparatus.

  Next, the operation of the heat pump type water heater 1 of the present embodiment having the above configuration will be described. When the operation switch of the remote controller 50 is turned on in a state where power is supplied to the heat pump hot water heater 1 from the outside, the control device 40 executes a control process (control program) stored in advance in the storage circuit.

  In this control process, a boiling operation control process for storing hot water heated in the hot water storage tank 20 by the water-refrigerant heat exchanger 12 of the refrigeration cycle apparatus 10 is executed.

  In the boiling operation, the control device 40 reads the operation signal of the remote controller 50 and the detection signal detected by the sensor groups 41 to 46 and the like, and performs various controls of the refrigeration cycle apparatus 10 based on the read operation signal and detection signal. The control signal or control voltage output to the target devices 11, 13, 14a and the water circulation pump 34 is determined.

  For example, the control signal output to the compressor 11 (specifically, the electric motor of the compressor 11) is stored in the control device 40 in advance based on the detected outside air temperature Tam detected by the outside air temperature sensor 45. Determined with reference to the control map. More specifically, the target rotational speed (target refrigerant discharge capacity) of the compressor 11 is determined to increase as the outside air temperature Tam decreases.

  The control signal output to the electric expansion valve 13 (specifically, the electric actuator of the electric expansion valve 13) is detected by the high pressure side pressure sensor 46 using a feedback control method or the like. The refrigerant pressure Pd is determined to be the target high pressure. The target high pressure is set so that the coefficient of performance (COP) of the refrigeration cycle apparatus 10 becomes a maximum value with reference to a control map stored in advance in the control apparatus 40 based on the outside air temperature Tam, the high-pressure side refrigerant pressure Pd, and the like. To be determined.

  The control voltage output to the blower fan 14a is determined with reference to a control map stored in advance in the control device 40 based on the outside air temperature Tam.

  Moreover, about the control voltage output to the water circulation pump 34, using the feedback control method etc., the boiling temperature Two detected by the boiling temperature sensor 43 is set to the target boiling temperature Tw (in this embodiment, 90 degreeC). To be determined. This target boiling temperature Tw can suppress the temperature of hot water stored in the hot water storage tank 20 by the boiling operation to a temperature at which Legionella bacteria in the hot water storage tank 20 can be killed or the growth of Legionella bacteria. It is set to be above the temperature.

  And the control apparatus 40 outputs the control signal and control voltage which were determined as mentioned above to various control object apparatus. After that, until a predetermined boiling end condition is satisfied, a control routine such as reading a detection signal and an operation signal → determining a control state of various control target devices → outputting control voltages and control signals to various control target devices Is repeated.

  Therefore, during the boiling operation, the high-temperature and high-pressure refrigerant discharged from the compressor 11 of the refrigeration cycle apparatus 10 flows into the refrigerant passage 12a of the water-refrigerant heat exchanger 12, and is pumped to the water passage 12b by the water circulation pump 34. Exchange heat with hot water. Thereby, the hot water flowing into the water passage 12b is heated so as to reach the target boiling temperature Tw.

  The high-pressure refrigerant flowing out of the water-refrigerant heat exchanger 12 is decompressed by the electric expansion valve 13. The refrigerant decompressed by the electric expansion valve 13 flows into the outdoor heat exchanger 14, absorbs heat from the outside air blown from the blower fan 14a, and evaporates. The refrigerant flowing out of the outdoor heat exchanger 14 is sucked into the compressor 11 and compressed again.

  On the other hand, the hot water heated by the water-refrigerant heat exchanger 12 flows into the upper side of the hot water storage tank 20 via the high temperature side water pipe 32 and is stored in the hot water storage tank 20. As described above, since the hot water storage tank 20 of the present embodiment is formed in a vertically long shape whose axial direction extends in a substantially vertical direction, the hot water in the hot water storage tank 20 when the boiling operation is finished is A temperature distribution is generated in which the temperature gradually decreases from the side toward the lower side.

  Further, in the control device 40 of the present embodiment, using the timer means or the like, the boiling operation is executed in the midnight power time zone (for example, from 23:00 to 7:00 the next morning) in which inexpensive commercial power can be used at night. Yes. Thereby, in the heat pump type hot water heater 1 of this embodiment, the electric power cost required in order to boil the hot water stored in the hot water storage tank 20 is reduced.

  Here, as in the refrigeration cycle apparatus 10 of the present embodiment, in the configuration in which the low-pressure refrigerant is evaporated by exchanging heat between the low-pressure refrigerant and the outside air in the outdoor heat exchanger 14, the refrigerant evaporation temperature in the outdoor heat exchanger 14 is If the frosting temperature (specifically, 0 ° C.) or less is reached, frosting may occur in the outdoor heat exchanger 14.

  Such frosting blocks the outdoor air passage of the outdoor heat exchanger 14 and significantly reduces the heat exchange performance of the outdoor heat exchanger 14, thereby reducing the heat absorption amount of the refrigerant in the outdoor heat exchanger 14. End up. As a result, the heating capacity of hot water in the refrigeration cycle apparatus 10, that is, the heating capacity of hot water in the water-refrigerant heat exchanger 12 is reduced.

  The heating capacity of the hot water supply in the water-refrigerant heat exchanger 12 of the present embodiment is the enthalpy obtained by subtracting the enthalpy of the refrigerant passage 12a outlet side refrigerant from the enthalpy of the refrigerant passage 12a inlet side refrigerant of the water-refrigerant heat exchanger 12. It is defined by a value obtained by integrating the difference and the flow rate (mass flow rate) of the high-pressure refrigerant flowing through the water-refrigerant heat exchanger 12.

  Therefore, in the refrigeration cycle apparatus 10 of the present embodiment, when it is determined that frost formation has occurred in the outdoor heat exchanger 14 by the control device 40 executing the control process shown in the flowchart of FIG. The frost formation on the heat exchanger 14 or the frost formation on the outdoor heat exchanger 14 is prevented from proceeding.

  The control process shown in FIG. 2 is executed at predetermined control cycles as a subroutine of the boiling operation control process that is the main routine. Further, each control step in the flowchart of FIG. 2 constitutes various function realizing means possessed by the control device 40.

  First, in step S11, it is determined whether or not frost formation has occurred in the outdoor heat exchanger 14. Specifically, in step S11, when the temperature difference (Tam−Te) obtained by subtracting the evaporator temperature Te detected by the evaporator temperature sensor 44 from the outside air temperature Tam is equal to or greater than a predetermined reference temperature difference. Then, it is determined that frost formation has occurred in the outdoor heat exchanger 14.

  Therefore, this step S11 comprises the frost formation determination means described in the claims. Furthermore, in step S11 of this embodiment, in order to determine whether or not frost formation has actually occurred in the outdoor heat exchanger 14, whether or not the outdoor heat exchanger 14 has operating conditions that can cause frost formation. Judging. In other words, in Step S11, it can be expressed that it is determined whether or not there is a possibility that frost formation has occurred in the outdoor heat exchanger 14.

  And when it determines with the frost formation having arisen in the outdoor heat exchanger 14 in step S11, it progresses to step S12 and it is not determined with the frost formation having occurred in the outdoor heat exchanger 14 Return to the main routine.

  In step S12, the discharge capacity control means 40a of the control device 40 gradually increases the refrigerant discharge capacity (rotation speed) of the compressor 11 so that the target refrigerant discharge capacity stored in the target value storage means 40c is obtained. Further, the throttle opening degree control means 40b of the control device 40 gradually increases the throttle opening degree of the electric expansion valve 13 so that the target throttle opening degree stored in the target value storage means 40c is obtained.

  Here, the target value storage means 40c stores the target refrigerant discharge capacity and the target throttle opening corresponding to the evaporator temperature Te as shown in the control characteristic diagram of FIG. Details of this control characteristic diagram will be described later. Further, in step S12, the process returns to the main routine after a predetermined standby time has elapsed.

  Next, when hot water from the various hot water supply terminals is requested in a state where hot hot water is stored in the hot water storage tank by the boiling operation, the control device 40 causes the hot water to be discharged from the various hot water terminals. The operation of the temperature adjustment valve is controlled so that the temperature becomes the target hot water temperature of each hot water supply terminal set by the temperature setting switch of the remote controller 50. Note that “when hot water is requested from various hot water supply terminals” in the present embodiment corresponds to “when a user performs hot water operation (opening operation) such as a faucet or shower”.

  As described above, in the heat pump type hot water heater 1 of the present embodiment, hot water is stored in the hot water storage tank 20 by performing the boiling operation. Then, by mixing the tap water with the hot hot water stored in the hot water storage tank 20 by the temperature adjustment valve, the hot water adjusted to the user's desired temperature can be discharged from each hot water terminal.

  Furthermore, according to the refrigeration cycle apparatus 10 of the present embodiment, when it is determined in control step S11 that constitutes the frost determination means that frost formation has occurred in the outdoor heat exchanger 14, the control step S12 is performed. Thus, the throttle opening of the electric expansion valve 13 is increased.

  Thereby, the pressure of the low-pressure refrigerant flowing into the outdoor heat exchanger 14 can be increased, and the refrigerant evaporation temperature in the outdoor heat exchanger 14 can be increased. Therefore, it can suppress that frost formation arises in the outdoor heat exchanger 14, or that frost formation of the outdoor heat exchanger 14 advances.

  In addition to this, when it is determined in control step S11 that frost formation has occurred in the outdoor heat exchanger 14, the refrigerant discharge capacity (rotation speed) of the compressor 11 is increased in control step S12. Therefore, the flow rate of the refrigerant flowing through the refrigerant passage 12a of the water-refrigerant heat exchanger 12 can be increased.

  Thereby, even if the refrigerant | coolant evaporation temperature in the outdoor heat exchanger 14 is raised and the heat absorption amount of the low-pressure refrigerant | coolant in the outdoor heat exchanger 14 is reduced, the heating capability of the hot water supply in the water-refrigerant heat exchanger 12 is sufficient. It can suppress that it falls.

  As a result, according to the refrigeration cycle apparatus 10 of the present embodiment, it is possible to suppress a decrease in the heating capacity of the hot water supply due to frost formation of the outdoor heat exchanger 14 without causing an increase in noise of the blower fan 14a.

  Here, when it is determined in control step S11 that frost formation has occurred in the outdoor heat exchanger 14, if the throttle opening of the electric expansion valve 13 is greatly increased, the outdoor temperature Tam and the outdoor heat exchange are increased. There is a possibility that the temperature difference from the refrigerant evaporating temperature in the condenser 14 is reduced, and the heat absorption amount of the refrigerant in the outdoor heat exchanger 14 is greatly reduced.

  Furthermore, if the throttle opening degree of the electric expansion valve 13 is unnecessarily increased, the saturation temperature of the refrigerant in the outdoor heat exchanger 14 becomes higher than the outdoor temperature Tam, and the low-pressure refrigerant is discharged from the outdoor heat exchanger 14 to the outside air. Will not be able to absorb heat. Therefore, when it is determined that frost formation has occurred in the outdoor heat exchanger 14, the throttle opening of the electric expansion valve 13 is increased so as not to greatly reduce the heat absorption amount of the refrigerant in the outdoor heat exchanger 14. It is desirable to make it.

  On the other hand, when it is determined that frost formation has occurred in the outdoor heat exchanger 14, if the refrigerant discharge capacity of the compressor 11 is greatly increased, the operating noise (noise) of the compressor 11 increases, and this operating noise is increased. May be annoying to the user. Therefore, when it is determined that frost formation has occurred in the outdoor heat exchanger 14, it is desirable to increase the refrigerant discharge capacity of the compressor 11 so that the noise of the compressor 11 does not increase.

  Therefore, in the present embodiment, the target value storage means 40c stores the target throttle opening and the target refrigerant discharge capacity corresponding to the evaporator temperature Te as shown in the control characteristic diagram of FIG. Both the heat absorption amount of the refrigerant in the heat exchanger 14 is greatly reduced and the noise of the compressor 11 is increased.

  More specifically, in the control characteristic diagram of FIG. 3, a broken line extending from the lower left side to the upper right side represents a change in the evaporator temperature Te. Further, the horizontal axis in FIG. 3 represents the target refrigerant discharge capacity corresponding to the evaporator temperature Te, and the vertical axis in FIG. 3 represents the target throttle opening corresponding to the evaporator temperature Te.

For example, the evaporator temperature Te when it is determined that frost formation has occurred in the outdoor heat exchanger 14 is −5 with respect to the normal time when it is not determined that frost formation has occurred in the outdoor heat exchanger 14. If it is ° C., the target refrigerant discharge capacity is increased to N ₅ and the target throttle opening is increased to O ₅ . Further, if the evaporator temperature Te when it is determined that frost formation has occurred in the outdoor heat exchanger 14 is −10 ° C., the target refrigerant discharge capacity is increased to N ₁₀ and the target throttle opening is set to O Increase to ₁₀ .

Furthermore, as shown in FIG. 3, since N ₅ <N ₁₀ and O ₅ <O ₁₀ , the target value storage unit 40c of the present embodiment has a reduction in the evaporator temperature Te. The target refrigerant discharge capacity and the target throttle opening are stored so as to increase.

  Thus, it is determined that frost formation has occurred in the outdoor heat exchanger 14 because the target value storage unit 40c stores in advance the target throttle opening and the target refrigerant discharge capacity corresponding to the evaporator temperature Te. When this is done, it is possible to reliably prevent both the throttle opening of the electric expansion valve 13 and the refrigerant discharge capacity of the compressor 11 from being unnecessarily increased. As a result, it is possible to reliably suppress both the heat absorption amount of the refrigerant in the outdoor heat exchanger 14 from greatly decreasing and the noise of the compressor 11 from increasing.

(Second Embodiment)
This embodiment demonstrates the example which changed the control aspect of control step S12 of FIG. 2 with respect to 1st Embodiment.

  In control step S12 of the present embodiment, the discharge capacity control means 40a gradually increases the refrigerant discharge capacity (rotation speed) of the compressor 11 within the range of the target refrigerant discharge capacity stored in the target value range storage means 10d. Further, the throttle opening degree control means 40b gradually increases the throttle opening degree of the electric expansion valve 13 within the range of the target throttle opening degree stored in the target value range storage means 10d.

  That is, the target value range storage means 10d stores a target refrigerant discharge capacity range and a target throttle opening range corresponding to the evaporator temperature Te as shown in the control characteristic diagram of FIG. Further, in the range of the target refrigerant discharge capacity and the range of the target throttle opening, the amount of heat absorbed by the refrigerant in the outdoor heat exchanger 14 is greatly reduced and the noise of the compressor 11 is the same as in the first embodiment. Is a range determined so as to be able to suppress both of the increase.

  More specifically, in the control characteristic diagram of FIG. 4, the alternate long and short dash line and the broken line extending from the lower left side to the upper right side represent changes in the evaporator temperature Te. Furthermore, the upper one-dot chain line indicates the lower limit value of the target refrigerant discharge capacity range and the upper limit value of the target throttle opening degree according to the evaporator temperature Te. On the other hand, the lower broken line indicates the upper limit value of the target refrigerant discharge capacity range and the lower limit value of the target throttle opening degree according to the evaporator temperature Te.

  Therefore, in the region between the upper one-dot chain line and the lower dashed line in FIG. 4, the heat absorption amount of the refrigerant in the outdoor heat exchanger 14 is greatly reduced, and the noise of the compressor 11 is increased. This is a region where both of these can be suppressed.

  Further, in the region above the upper one-dot chain line in FIG. 4 (the region indicated by hatching in FIG. 4), the throttle opening of the electric expansion valve 13 becomes large, and the heat absorption amount of the refrigerant in the outdoor heat exchanger 14 is increased. This is a region where there is a risk of a significant decrease. On the other hand, in the region below the broken line on the lower side in the drawing (the region indicated by hatching in FIG. 5), the refrigerant discharge capacity of the compressor 11 increases, and the noise of the compressor 11 may increase. There will be an area.

For example, the evaporator temperature Te when it is determined that frost formation has occurred in the outdoor heat exchanger 14 is −5 with respect to the normal time when it is not determined that frost formation has occurred in the outdoor heat exchanger 14. If it is ° C., the range of the target refrigerant discharge capacity is N _{5 min} or more and N _{5 max} or less shown in FIG. Similarly, the range of the target throttle opening is O _{5 min} or more and O _5max or less shown in FIG.

Furthermore, if the evaporator temperature Te is −10 ° C., the range of the target refrigerant discharge capacity is N _{10 min} or more and N _{10 max} or less shown in FIG. Similarly, the range of the target throttle opening is O _{10 min} or more and O _10max or less shown in FIG.

Furthermore, as shown in FIG. 4, N _5min <N _10min, and N _5max <has become a relation of N _10Max, it has a relationship of O _5min <O _10min, and O _5max <O _10max. Accordingly, the target value range storage means 10d increases the lower limit value and upper limit value of the target refrigerant discharge capacity range and the lower limit value and upper limit value of the target throttle opening range as the evaporator temperature Te decreases. I remember that.

  Further, in the control step S12 of the present embodiment, when it is determined that frost formation has occurred in the outdoor heat exchanger 14 during the boiling operation performed in the late-night power time period, the upper one-dot chain line is used. The target refrigerant discharge capacity and the target throttle opening are determined. Further, even in the late-night power time zone, when a high heating capacity is required as in a low outside air temperature, the target refrigerant discharge capacity and the target throttle opening are determined using the lower broken line.

  Other configurations and operations are the same as those in the first embodiment. Therefore, also in the refrigeration cycle apparatus 10 of the present embodiment, as in the first embodiment, it is possible to suppress a decrease in the heating capacity of the hot water supply due to frost formation of the outdoor heat exchanger 14 without causing an increase in noise. it can.

  Furthermore, in the refrigeration cycle apparatus 10 of the present embodiment, when it is determined that frost formation has occurred in the outdoor heat exchanger 14 during the boiling operation performed in the late-night power hours, the upper one-dot chain line is used. Thus, the target refrigerant discharge capacity and the target throttle opening are determined.

  That is, the throttle opening degree control means 40b increases the throttle opening degree of the electric expansion valve 13 so that the upper limit value is within the range of the target throttle opening degree, and the discharge capacity control means 40a is within the range of the target refrigerant discharge capacity. The refrigerant discharge capacity of the compressor 11 is increased so that the lower limit value is reached. Therefore, it is possible to effectively suppress the noise of the compressor 11 from increasing during the midnight power hours.

  Also, when the outside air temperature is lower than the predetermined reference outside air temperature even in the late-night power hours and a high heating capacity is required, the target refrigerant discharge capacity and the target throttle are used using the lower broken line. Determine the opening.

  That is, the throttle opening degree control means 40b increases the throttle opening degree of the electric expansion valve 13 so that the lower limit value is within the range of the target throttle opening degree, and the discharge capacity control means 40a is within the range of the target refrigerant discharge capacity. The refrigerant discharge capacity of the compressor 11 is increased so that the upper limit value is reached. Therefore, when a high heating capacity is required, it is possible to effectively suppress a decrease in the heat absorption amount of the refrigerant in the outdoor heat exchanger 14.

  As described above, according to the refrigeration cycle apparatus 10 of the present embodiment, the heat absorption amount of the refrigerant in the outdoor heat exchanger 14 is greatly reduced by changing the target refrigerant discharge capacity and the target throttle opening according to the operating conditions. It is possible to appropriately obtain the effect of suppressing the noise and the effect of increasing the noise of the compressor 11.

  Of course, the target refrigerant discharge capacity and the target throttle opening are not limited to the upper limit value or the lower limit value, but are within the target refrigerant discharge capacity range and target throttle opening range shown in the control characteristic diagram of FIG. You may decide by.

  Furthermore, although FIG. 4 demonstrated the control characteristic figure from which the inclination of the upper dashed-dotted line and the lower broken line differed, these inclinations are not limited to this. That is, the slopes of the upper one-dot chain line and the lower dashed line may be determined according to the operating characteristics of the refrigeration cycle apparatus 10, and the upper one-dot chain line and the lower dashed line may have the same slope.

(Third embodiment)
In the present embodiment, compared to the first embodiment, a subroutine for suppressing the frost formation in the outdoor heat exchanger 14 or the frost formation of the outdoor heat exchanger 14 proceeds. An example in which the control mode is changed as shown in the flowchart of FIG. 5 will be described.

  In step S11 of the present embodiment, it is determined whether frost formation has occurred in the outdoor heat exchanger 14 as in the first embodiment. When it is determined in step S11 that frost formation has occurred in the outdoor heat exchanger 14, the process proceeds to step S13, and when it has not been determined that frost formation has occurred in the outdoor heat exchanger 14 Return to the main routine.

  In step S13, the driving torque of the compressor 11 when it is determined that frost formation has occurred in the outdoor heat exchanger 14 is calculated. Specifically, the driving torque of the compressor 11 is calculated using the refrigerant evaporating pressure (low-pressure side refrigerant pressure) in the outdoor heat exchanger 14 obtained from the high-pressure side refrigerant pressure Pd and the evaporator temperature Te, and the process proceeds to step S14. move on. Therefore, step S13 of the present embodiment constitutes a torque calculation means described in the claims.

  In step S14, the throttle opening degree control is performed so that the driving torque of the compressor 11 calculated in step S13 is maintained (that is, the driving torque of the compressor 11 calculated in step S13 does not change). The means 40b gradually increases the throttle opening of the electric expansion valve 13, and the discharge capacity control means 40a gradually increases the refrigerant discharge capacity (rotation speed) of the compressor 11.

  Specifically, in step S14, the target throttle opening degree of the electric expansion valve 13 is determined based on the evaporator temperature Te with reference to the control map stored in the target value storage means 40c. Further, based on the determined target throttle opening, the target refrigerant discharge capacity of the compressor 11 is determined as shown in the control characteristic diagram of FIG.

  More specifically, in the control characteristic diagram of FIG. 6, a solid line extending from the lower left side toward the upper right side indicates a line where the driving torque of the compressor 11 is constant. In FIG. 6, three solid lines are illustrated, but these lines represent different drive torques Ta, Tb, and Tx, respectively, and there is a relationship of Ta <Tx <Tb. Further, the broken lines on both sides of the solid line indicating the driving torque Tx indicate the allowable error range of the driving torque.

For example, when the evaporator temperature Te when it is determined that frost formation has occurred in the outdoor heat exchanger 14 is −X ° C. and the driving torque of the compressor 11 is Tx, an ideal target. The refrigerant discharge capacity is determined to be Nx shown in FIG. 6, and Nx is determined to be Nx _min or more and Nx _max or less from the allowable error range.

  Then, the throttle opening of the electric expansion valve 13 is increased so that the target throttle opening determined as described above becomes Ox, and the target refrigerant discharge capacity determined as described above is set to Nx. The refrigerant discharge capacity (rotation speed) of the compressor 11 is increased. Other configurations and operations are the same as those in the first embodiment.

  Therefore, also in the refrigeration cycle apparatus 10 of the present embodiment, as in the first embodiment, it is possible to suppress a decrease in the heating capacity of the hot water supply due to frost formation of the outdoor heat exchanger 14 without causing an increase in noise. it can.

  More specifically, in the refrigeration cycle apparatus 10 of the present embodiment, when it is determined that frost formation has occurred in the outdoor heat exchanger 14, an increase in driving torque that causes a noise increase in the compressor 11 is increased. The refrigerant discharge capacity of the compressor 11 is increased so as to suppress it. Therefore, it can suppress effectively that the noise of the compressor 11 becomes large.

  Here, “the driving torque of the compressor (11) is maintained” described in the claims is limited to the meaning of “the driving torque of the compressor 11 is maintained so as not to change at all”. It also means that the driving torque of the compressor (11) is maintained within a predetermined allowable error range as in this embodiment.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present invention.

  (1) In the above-described embodiment, whether or not frost formation has occurred in the outdoor heat exchanger 14 is determined based on the temperature difference (Tam-Te) in the control step S1 constituting the frost determination means. Although the example was demonstrated, the specific determination conditions in a frost determination means are not limited to this. For example, the frost determination means may determine that frost is generated in the outdoor heat exchanger 14 when the outside air temperature Tam is 0 ° C. or less, and the evaporator temperature Te is predetermined. When the temperature is equal to or lower than the reference frost temperature, it may be determined that frost is generated in the outdoor heat exchanger 14.

  (2) In the above-described embodiment, details of the end condition of the boiling operation are not described. However, as the end condition of the boiling operation, for example, the temperature sensor 41 in the tank constituted by a plurality of temperature sensors may be used. Of these, the boiling operation may be terminated when the temperature detected by a predetermined temperature sensor (for example, the temperature sensor disposed on the lowermost side) reaches a predetermined boiling operation end temperature.

  Further, the total amount of heat supplied to the hot water supply in the hot water storage tank 20 calculated from the boiling temperature Two detected by the boiling temperature sensor 43, the water pressure feeding capacity of the water circulation pump 34, the operating time of the refrigeration cycle apparatus 10, and the like. The boiling operation may be terminated when becomes equal to or greater than a predetermined reference total heat quantity. Further, the boiling operation may be terminated when a predetermined time elapses from the start of the boiling operation.

  (3) In the third embodiment described above, the drive torque of the compressor 11 is calculated in the control step S13, and the compressor 11 and the electric expansion valve 13 are operated so that the calculated drive torque is maintained. However, the torque detection means may be provided by detecting the driving torque of the compressor 11, and the detection signal of the torque detection means may be read in the control step S13.

  Furthermore, in 3rd Embodiment, the target refrigerant | coolant discharge capability of the compressor 11 was determined using the target throttle opening determined based on the evaporator temperature Te so that the drive torque of the compressor 11 may be maintained. Although the example has been described, conversely, the target throttle opening degree of the electric expansion valve 13 is maintained such that the driving torque of the compressor 11 is maintained using the target refrigerant discharge capacity determined based on the evaporator temperature Te. May be determined.

  (4) In the above-described embodiment, the example in which the electric compressor is adopted as the compressor 11 has been described, but the compressor 11 is not limited to this. For example, an engine-driven compressor driven by a rotational driving force transmitted from an internal combustion engine (engine) via a pulley, a belt, or the like may be employed as the compressor. As the engine-driven compressor, a variable capacity compressor that can adjust the refrigerant discharge capacity by changing the discharge capacity can be adopted.

  (5) In the above-described embodiment, an example in which a faucet, a shower, and the like are provided as a hot water supply terminal has been described. However, as a hot water supply terminal, a hot water terminal for a bathtub that discharges hot water to the bathtub, a hot water panel for floor heating, or A hot water panel for wall heating may be provided.

  (6) In the refrigeration cycle apparatus 10 of the above-described embodiment, carbon dioxide is used as a refrigerant to constitute a supercritical refrigeration cycle. However, the present invention is not limited to this, and a chlorofluorocarbon refrigerant, an HC refrigerant, or the like is used as the refrigerant. Thus, a subcritical refrigeration cycle in which the high-pressure side refrigerant pressure of the cycle does not exceed the critical pressure of the refrigerant may be configured.

11 Compressor 12 Water-refrigerant heat exchanger (heat radiator)
13 Electric expansion valve (pressure reduction means)
14 Outdoor heat exchanger (evaporator)
40a discharge capacity control means 40b throttle opening control means

Claims (8)

A compressor (11) for compressing and discharging the refrigerant;
A radiator (12) that heats the fluid to be heated by exchanging heat between the high-pressure refrigerant discharged from the compressor (11) and the fluid to be heated;
Decompression means (13) for decompressing the refrigerant flowing out of the radiator (12);
An evaporator (14) for exchanging heat between the low pressure refrigerant decompressed by the decompression means (13) and the outside air to evaporate the low pressure refrigerant;
Discharge capacity control means (40a) for controlling the refrigerant discharge capacity of the compressor (11);
Throttle opening control means (40b) for controlling the throttle opening of the pressure reducing means (13);
Frosting determination means (S11) for determining whether or not frost is generated in the evaporator (14),
When the frosting determination means (S11) determines that frost formation has occurred in the evaporator (14), the discharge capacity control means (40a) increases the refrigerant discharge capacity and the throttle opening degree. The refrigeration cycle apparatus characterized in that the control means (40b) increases the throttle opening of the pressure reducing means (13). Evaporator temperature detecting means (44) for detecting the temperature of the evaporator (14);
Target value storage means (40c) for storing the target refrigerant discharge capacity and target throttle opening corresponding to the evaporator temperature (Te) detected by the evaporator temperature detection means (44),
The target value storage means (40c) stores the target refrigerant discharge capacity and the target throttle opening so as to increase as the evaporator temperature (Te) decreases.
When the frosting determination means (S11) determines that frost formation has occurred in the evaporator (14), the refrigerant discharge capacity is set so that the discharge capacity control means (40a) becomes the target refrigerant discharge capacity. The refrigeration cycle apparatus according to claim 1, wherein the throttle opening degree is increased so that the throttle opening degree control means (40b) reaches the target throttle opening degree. Evaporator temperature detecting means (44) for detecting the temperature of the evaporator (14);
A target value range storage means (10d) for storing a target refrigerant discharge capacity range and a target throttle opening range corresponding to the evaporator temperature (Te) detected by the evaporator temperature detection means (44);
The target value range storage means (10d) has a lower limit value and an upper limit value of the range of the target refrigerant discharge capacity, and a lower limit value of the range of the target throttle opening as the evaporator temperature (Te) decreases. And remember to increase the upper limit,
When the frost determination means (S11) determines that frost is generated in the evaporator (14), the discharge capacity control means (40a) is within the range of the target refrigerant discharge capacity. The refrigeration cycle apparatus according to claim 1, wherein the throttle opening control means (40b) increases the throttle opening within a range of the target throttle opening.   When the frosting determination means (S11) determines that frost formation has occurred in the evaporator (14), the discharge capacity control means (40a) becomes an upper limit value within the range of the target refrigerant discharge capacity. The refrigeration cycle apparatus according to claim 3, wherein the refrigerant discharge capacity is increased as described above.   When the frosting determination means (S11) determines that frost formation has occurred in the evaporator (14), the throttle opening degree control means (40b) has an upper limit value within the range of the target throttle opening degree. The refrigeration cycle apparatus according to claim 3, wherein the throttle opening is increased so as to become.   When the frosting determination means (S11) determines that frost formation has occurred in the evaporator (14), the discharge capacity control means (so that the driving torque of the compressor (11) is maintained. The refrigeration cycle apparatus according to claim 1, wherein 40a) increases the refrigerant discharge capacity, and the throttle opening control means (40b) increases the throttle opening of the pressure reducing means (13). High pressure side pressure detecting means (46) for detecting the pressure of the high pressure side refrigerant from the discharge port of the compressor (11) to the inlet side of the pressure reducing means;
Torque calculating means (S13) for calculating the driving torque of the compressor (11) using at least the high pressure side refrigerant pressure (Pd) detected by the high pressure side pressure detecting means (46). The refrigeration cycle apparatus according to claim 6.   The refrigeration cycle apparatus according to claim 6, further comprising torque detection means for detecting a drive torque of the compressor (11).

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