JP5082865B2 - Heat pump device, hot water supply device including the same, and control device therefor - Google Patents

Description

  The present invention relates to a heat pump device, a hot water supply device including the heat pump device, and a control device therefor.

Patent Document 1 discloses a conventional heat pump device. In this heat pump device, the defrosting operation of the refrigerant evaporator is performed as follows. That is, when frost accumulates in the refrigerant evaporator and starts the defrosting operation, first, the rotational speed of the compressor is increased to f1. Thereafter, when the piping temperature TA on the refrigerant evaporator outlet side rises and exceeds the first set temperature T2, the rotation speed of the compressor is reduced to f2 (f2 <f1). When the pipe temperature TA further increases and exceeds the second set temperature T0 (T0> T2), the defrosting operation is terminated. In this heat pump device, since the rotation speed of the compressor is reduced during the defrosting operation, noise from the compressor and power consumption in the compressor can be reduced.
JP-A-63-273750 (4th page, FIG. 7 and FIG. 8)

  However, the flow rate of the high-temperature refrigerant that needs to flow into the refrigerant evaporator during the defrosting operation differs depending on the outside air temperature. For this reason, if the rotation speed of the compressor is reduced during the defrosting operation, depending on the outside air temperature, the flow rate of the high-temperature refrigerant may be insufficient, and it may take a long time for the defrosting, or frost may remain unmelted. There is a problem.

  The objective of this invention is providing the heat pump apparatus which can reduce the noise from the compressor during a defrost operation, and can prevent the frost from being melt | dissolved, a hot-water supply apparatus provided with the heat pump apparatus, and its control apparatus.

  In order to achieve the above object, the present invention employs the following technical means.

The invention described in claim 1 includes at least a compressor (30), a high-pressure side heat exchanger (40), and a low-pressure side heat exchanger (60), a heat pump cycle (20) for circulating the refrigerant, and a low-pressure side heat. Refrigerant temperature sensors (63, 64) for detecting the refrigerant temperature of the refrigerant flowing out from the exchanger (60), and an outside air temperature sensor (62) for detecting the outside air temperature of the outside air blown to the low-pressure side heat exchanger (60 ). And a control unit (10) that performs defrost control for defrosting the frost attached to the low-pressure side heat exchanger (60), and the control unit (10) includes a compressor when performing the defrost control. When the rotational speed of (30) is set to the first rotational speed (RCa) and the refrigerant temperature is equal to or higher than the second temperature (TFa) , the pressure is increased when the outside air temperature is equal to or higher than the first temperature (TGa). The rotation speed of the compressor (30) is changed from the first rotation speed (RCa) to the first rotation speed (RCa). When the outside air temperature is lower than the first temperature (TGa), the rotation speed of the compressor (30) is maintained at the first rotation speed (RCa). This is a heat pump device.

Accordingly, when the outside air temperature is relatively high, the rotation speed of the compressor (30) during the defrosting operation can be reduced from the first rotation speed (RCa) to the second rotation speed (RCb). Noise from the machine (30) can be reduced. On the other hand, when the outside air temperature is relatively low,
A sufficient amount of high-temperature refrigerant can be caused to flow into the low-pressure heat exchanger (60) while maintaining the rotation speed of the compressor (30) at the first rotation speed (RCa), thereby preventing frost from remaining unmelted. it can. Furthermore, when the outside air temperature is relatively low, a high-temperature refrigerant having a sufficient flow rate can be caused to flow into the air refrigerant heat exchanger 60, so that frost can be prevented from being melted and defrosting can be completed in a short time.

In the invention according to claim 2 , the compressor (30) is provided so as to suck the refrigerant flowing out from the low-pressure side heat exchanger (60), and the refrigerant temperature sensor (64) is provided in the compressor (30). It is provided on the suction side. Since the refrigerant temperature on the suction side of the compressor (30) is substantially equal to the refrigerant temperature on the outlet side of the low-pressure side heat exchanger (60), the same effect as the above-described invention can be obtained.

As in the third aspect of the invention, carbon dioxide may be used as the refrigerant.

In each of the above inventions, as in the invention described in claim 4 , a heat pump device, a hot water storage tank (70) for storing hot water heated by the heat pump device, and hot water in the hot water storage tank (70) are supplied to the outside. The present invention can be applied to a hot water supply device having a hot water supply channel (72).

The invention according to claim 5 includes at least a compressor (30), a high pressure side heat exchanger (40), and a low pressure side heat exchanger (60), a heat pump cycle (20) for circulating the refrigerant, and a low pressure side heat. A refrigerant temperature sensor (63) for detecting the refrigerant temperature of the refrigerant flowing out from the exchanger (60), and an outside air temperature sensor (62) for detecting the outside air temperature of the outside air blown to the low-pressure side heat exchanger (60). The heat pump device (2) includes a heat pump device control device that performs defrosting control for defrosting frost adhering to the low-pressure side heat exchanger (60). the rotational speed of 30) is set to a first rotational speed (RCa), the refrigerant temperature becomes the second temperature (TFa) above, when the outside air temperature is above a first temperature (TGa) is compressed The number of revolutions of the machine (30) is the first number of revolutions (RCa) When the outside air temperature is lower than the first temperature (TGa), the rotational speed of the compressor (30) is decreased to the second rotational speed (RCb) lower than the first rotational speed (RCa). It is a control device for a heat pump device, characterized in that it is maintained at a rotational speed of 1 (RCa).

Thus, similarly to the first aspect of the invention, when the outside air temperature is relatively high, the rotation speed of the compressor (30) during the defrosting operation is changed from the first rotation speed (RCa) to the second rotation speed ( RCb), the noise from the compressor (30) can be reduced. On the other hand, when the outside air temperature is relatively low, a sufficient amount of high-temperature refrigerant is allowed to flow into the low-pressure side heat exchanger (60) while maintaining the rotation speed of the compressor (30) at the first rotation speed (RCa). Therefore, it is possible to prevent frost from remaining unmelted. Furthermore, when the outside air temperature is relatively low, a high-temperature refrigerant having a sufficient flow rate can be caused to flow into the air refrigerant heat exchanger 60, so that frost can be prevented from being melted and defrosting can be completed in a short time.

  In addition, the code | symbol in the bracket | parenthesis of each said means has shown an example of the corresponding relationship with the specific means as described in embodiment mentioned later.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 schematically shows a schematic configuration of a hot water supply apparatus 1 in the present embodiment. As shown in FIG. 1, the hot water supply device 1 includes a heat pump device 2 that heats water by heat exchange with a high-temperature and high-pressure refrigerant. In the heat pump device 2, a compressor 30, a water refrigerant heat exchanger (high-pressure side heat exchanger) 40, an expansion valve 50, and an air refrigerant heat exchanger (low-pressure side heat exchanger) 60 are sequentially connected in an annular manner through a refrigerant pipe. And a heat pump cycle 20 for circulating the refrigerant. Carbon dioxide (CO ₂ ) is used as the refrigerant.

  The compressor 30 is an electric fluid device that compresses and discharges the refrigerant in the heat pump cycle 20 to a high temperature and a high pressure. The number of rotations of the compressor 30 is variably set by an inverter device (not shown) based on a control signal from the control device 10 described later. The water-refrigerant heat exchanger 40 has a water flow path and a refrigerant flow path, and heat exchange heats water flowing through the water flow path by heat exchange with a high-temperature and high-pressure refrigerant discharged from the compressor 30 and flowing through the refrigerant flow path. It is a vessel.

  The expansion valve 50 is a decompression unit that decompresses and expands the refrigerant that has flowed out of the water-refrigerant heat exchanger 40 in an enthalpy manner. The throttle opening of the expansion valve 50 is variably set based on a control signal from the control device 10. The air refrigerant heat exchanger 60 is a heat exchanger that evaporates the low-pressure refrigerant decompressed by the expansion valve 50 by heat exchange with the outside air blown by the blower fan 61. The low-pressure refrigerant that has flowed out of the air-refrigerant heat exchanger 60 flows into the suction side of the compressor 30.

  An outside air temperature sensor 62 is provided on the upstream side of the air flow from the air refrigerant heat exchanger 60. The outside air temperature sensor 62 detects the temperature of the outside air blown to the air refrigerant heat exchanger 60 by the blower fan 61 and outputs a detection signal to the control device 10.

  A refrigerant temperature sensor 63 is provided on the refrigerant outlet side of the air refrigerant heat exchanger 60. The refrigerant temperature sensor 63 detects the temperature of the refrigerant flowing out of the air refrigerant heat exchanger 60 and outputs a detection signal to the control device 10.

  The hot water supply device 1 has a hot water storage tank 70 that stores hot water heated by the water refrigerant heat exchanger 40 of the heat pump device 2. The hot water storage tank 70 is made of metal having excellent corrosion resistance and has a vertically long shape. A heat insulating material (not shown) is provided on the outer peripheral portion of the hot water storage tank 70 so that the hot water stored in the hot water storage tank 70 is kept warm for a long time. A predetermined temperature stratification is formed in the hot water storage tank 70 due to the difference in specific gravity of water due to the difference in temperature. The higher temperature hot water is stored in the upper part, and the lower temperature hot water (or water) is stored in the lower part.

  An inlet 70 a is provided on the bottom surface of the hot water storage tank 70. A water supply pipe 71 for introducing tap water having a predetermined pressure into the hot water storage tank 70 is connected to the introduction port 70a. A lead-out port 70 b is provided on the upper surface portion of the hot water storage tank 70. A hot water supply pipe (hot water supply flow path) 72 for supplying hot water in the hot water storage tank 70 to the outside is connected to the outlet 70b. Hot water mixing means (not shown) is connected to the downstream side of the hot water supply pipe 72. In the hot water mixing means, hot water having a predetermined temperature is generated by mixing hot hot water supplied via the hot water supply pipe 72 and tap water.

  The bottom surface of the hot water storage tank 70 is provided with a suction port 70c for sucking water in the hot water storage tank 70 from the outside. On the upper surface of the hot water storage tank 70, a discharge port 70d for discharging hot hot water into the hot water storage tank 70 is provided. The suction port 70c and the discharge port 70d are connected via a circulation circuit 73 that passes through the water flow path of the water-refrigerant heat exchanger 40. The circulation circuit 73 is provided with a circulation pump 74 that circulates water in the circulation circuit 73. The water in the circulation circuit 73 circulates in the water / refrigerant heat exchanger 40 so as to be opposed to the circulating refrigerant in the heat pump cycle 20. The circulation pump 74 operates based on a control signal from the control device 10 and outputs an operation state signal to the control device 10. The water sucked from the suction port 70 c and circulated through the circulation circuit 73 is boiled by heat exchange with the high-temperature refrigerant in the water-refrigerant heat exchanger 40 to become hot water, and returns to the upper part in the hot water storage tank 70.

  The control device (control unit) 10 includes a central processing unit (CPU) that performs various controls and operations, a read-only storage device (ROM) that stores various control programs and control constants, and an arbitrary storage area. 1 has a storage device (RAM) capable of writing and reading data, and an input / output port for inputting / outputting signals to / from the outside. Based on detection signals from various sensors including the outside air temperature sensor 62 and the refrigerant temperature sensor 63, the control device 10 includes the heat pump device 2 including the compressor 30, the expansion valve 50, the blower fan 61, the circulation pump 74, and the hot water supply. The operation control of the device 1 is performed.

  Next, the control method of the hot water supply apparatus 1 in the present embodiment will be described. The control device 10 controls the compressor 30, the expansion valve 50, the blower fan 61, the circulation pump 74, and the like based on detection signals from various sensors. Thus, normal boiling operation control is performed in which the water in the lower part of the hot water storage tank 70 is heated by the water / refrigerant heat exchanger 40 and returned to the upper part of the hot water storage tank 70 to store hot water of a predetermined amount of heat in the hot water storage tank 70.

  Moreover, the control apparatus 10 determines at any time whether the defrost operation for defrosting the frost adhering to the air refrigerant heat exchanger 60 is required during boiling operation control. For example, when the difference between the outside air temperature detected by the outside air temperature sensor 62 and the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60 detected by the refrigerant temperature sensor 63 exceeds a predetermined threshold, the control device 10 removes the air. Defrost control is performed by determining that frost operation is necessary.

  FIG. 2 is a flowchart showing an example of the flow of defrost control. As shown in FIG. 2, when the defrost control is started, the control device 10 stops the circulation pump 74 (step S1), and sets the opening of the expansion valve 50 to a predetermined opening (for example, fully open) (step S1). S2). Next, the control device 10 sets the rotational speed of the compressor 30 to a predetermined defrosting rotational speed RCa (first rotational speed) (step S3). By these steps S1 to S3, the high-temperature and high-pressure refrigerant discharged from the compressor 30 flows into the air refrigerant heat exchanger 60 while maintaining a high temperature, and the frost attached to the air refrigerant heat exchanger 60 is gradually melted. . When the amount of frost in the air refrigerant heat exchanger 60 decreases, the amount of heat released from the high-temperature refrigerant decreases, so the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60 increases with the progress of defrosting.

  When the above-described defrosting operation is started, the control device 10 performs compressor deceleration control for reducing the rotation speed of the compressor 30 when the compressor 30 can be decelerated in order to reduce noise and power consumption. Do. That is, the control device 10 is configured to reduce the rotational speed of the compressor 30 when it is determined that both of two conditions described later are satisfied.

  First, the controller 10 compares the outside temperature detected by the outside temperature sensor 62 with a predetermined threshold temperature TGa (first temperature; for example, −5 ° C.) (step S4). If the outside air temperature is equal to or higher than the threshold temperature TGa (outside air temperature ≧ TGa), the control device 10 determines that the outside air temperature condition for decelerating the compressor 30 is satisfied, and stores it in a predetermined flag storage area in the RAM. A compressor deceleration flag is set (step S5). On the other hand, if the outside air temperature is lower than the threshold temperature TGa (outside air temperature <TGa), the control device 10 determines that the outside air temperature condition is not satisfied, and proceeds to step S6.

  In step S6, the control device 10 compares the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60 detected by the refrigerant temperature sensor 63 with a predetermined threshold temperature TFa (second temperature; for example, 0 ° C.). If the refrigerant temperature is equal to or higher than the threshold temperature TFa (refrigerant temperature ≧ TFa), the control device 10 determines that the refrigerant temperature condition indicating that defrosting has progressed to a predetermined stage is satisfied, and proceeds to step S7. On the other hand, if the refrigerant temperature is lower than the threshold temperature TFa (refrigerant temperature <TFa), the control device 10 determines that the refrigerant temperature condition is not satisfied, and proceeds to step S9.

  In step S7, the control device 10 determines whether or not there is a compressor deceleration flag in the flag storage area in the RAM. If there is a compressor deceleration flag in the flag storage area, the control device 10 determines that both the outside air temperature condition and the refrigerant temperature condition are satisfied, and proceeds to step S8. In step S8, the control apparatus 10 changes the rotation speed of the compressor 30 from RCa to RCb (second rotation speed; RCa> RCb) smaller than RCa. On the other hand, if there is no compressor deceleration flag in the flag storage area in step S7, the control device 10 determines that at least the outside air temperature condition is not satisfied, and proceeds to step S9.

  In step S9, the control device 10 detects the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60 detected by the refrigerant temperature sensor 63, and the threshold temperature TFb higher than the threshold temperature TFa (for example, 5 ° C .; TFa <TFb). And compare. If the refrigerant temperature is equal to or higher than the threshold temperature TFb (refrigerant temperature ≧ TFb), the control device 10 determines that the defrosting of the air refrigerant heat exchanger 60 is completed, ends the defrosting operation, and returns to the normal boiling operation. Return. If the refrigerant temperature is lower than the threshold temperature TFb (refrigerant temperature <TFb), the process returns to step S6, and steps S6 to S9 are repeated.

  As described above, in this embodiment, when the outside air temperature is equal to or higher than the threshold temperature TGa, the compressor deceleration flag is set, and the rotation speed of the compressor 30 is controlled based on the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60. Is done. FIG. 3 is a graph showing changes in the rotational speed of the compressor 30 set by the control device 10 when the compressor deceleration flag is set. The horizontal axis of the graph represents the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60, and the vertical axis represents the rotational speed of the compressor 30. As shown in FIG. 3, when the compressor deceleration flag is set, when the refrigerant temperature rises and exceeds the threshold temperature TFa, the rotation speed of the compressor 30 immediately decreases from RCa to RCb. Thereby, when the outside air temperature is relatively high, the number of rotations of the compressor 30 during the defrosting operation can be reduced, so that noise from the compressor 30 and power consumption in the compressor 30 can be reduced.

  On the other hand, when the outside air temperature is lower than the threshold temperature TGa, the compressor deceleration flag is not set, and the rotation speed of the compressor 30 is maintained at RCa. When the outside air temperature is low, the amount of heat required for defrosting increases. Therefore, if the rotation speed of the compressor 30 is decreased during the defrosting operation, it takes a long time for defrosting or unmelted frost. May occur. However, according to this embodiment, when the outside air temperature is lower than TGa, the rotational speed of the compressor 30 is maintained at a relatively high speed until the defrosting is completed. Therefore, when the outside air temperature is relatively low, a high-temperature refrigerant having a sufficient flow rate can be caused to flow into the air refrigerant heat exchanger 60, so that frost can be prevented from being melted and defrosting can be completed in a short time.

  Moreover, in this embodiment, since the setting of the rotation speed of the compressor 30 in defrost control is two steps of RCa and RCb, said effect is acquired by simple control.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. Compared with the first embodiment, the present embodiment is characterized in that the rotational speed of the compressor 30 when the compressor deceleration flag is set is set stepwise based on the refrigerant temperature. Yes. FIG. 4 is a graph showing changes in the rotational speed of the compressor 30 set by the control device 10 when the compressor deceleration flag is set in the present embodiment. As shown in FIG. 4, in this embodiment, when the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60 rises and becomes equal to or higher than the threshold temperature TFa, the rotation speed of the compressor 30 is changed from RCa to RCc (RCa>RCc> RCb). ). Then, when the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60 further rises and becomes equal to or higher than the threshold temperature TFc (TFc> TFa), the rotation speed of the compressor 30 is switched from RCc to RCb.

  In the present embodiment, the number of revolutions of the compressor 30 is set to multiple stages (three stages in this example) based on the refrigerant temperature, so that the number of revolutions of the compressor 30 is necessary for performing defrosting without unmelted. It can approach the minimum number of rotations. Accordingly, the effect of reducing noise from the compressor 30 and power consumption in the compressor 30 is improved.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG. Compared with the first embodiment, the present embodiment is characterized in that the rotation speed of the compressor 30 when the compressor deceleration flag is set is continuously set based on the refrigerant temperature. Yes. FIG. 5 is a graph showing a change in the rotational speed of the compressor 30 set by the control device 10 when the compressor deceleration flag is set in the present embodiment. As shown in FIG. 5, in this embodiment, when the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60 rises and becomes equal to or higher than the threshold temperature TFa, the rotation speed of the compressor 30 is continuously increased as the refrigerant temperature rises. And it decreases monotonously. For example, the ROM of the control device 10 stores the rotational speed data corresponding to several refrigerant temperatures including the rotational speed RCa data corresponding to the refrigerant temperature TFa and the rotational speed RCb data corresponding to the refrigerant temperature TFb. Has been. The rotational speed at an arbitrary refrigerant temperature between TFa and TFb is calculated by the control device 10 by linear interpolation.

  In this embodiment, the rotation speed of the compressor 30 is continuously set based on the refrigerant temperature, so that the rotation speed of the compressor 30 is made closer to the minimum rotation speed necessary for performing defrosting without remaining unmelted. be able to. Accordingly, the effect of reducing noise from the compressor 30 and power consumption in the compressor 30 is further improved.

(Fourth embodiment)
Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 6 schematically shows a schematic configuration of the heat pump device 5 and the hot water supply device 4 in the present embodiment. As shown in FIG. 6, the heat pump device 5 of the present embodiment has a refrigerant temperature sensor 64 provided on the suction side of the compressor 30. The refrigerant temperature sensor 64 detects the temperature of the refrigerant that flows out of the air refrigerant heat exchanger 60 and is sucked into the compressor 30, and outputs a detection signal to the control device 10.

  In the first to third embodiments, the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60 detected by the refrigerant temperature sensor 63 is used as the refrigerant temperature flowing out from the air refrigerant heat exchanger 60. In the embodiment, the refrigerant temperature on the suction side of the compressor 30 detected by the refrigerant temperature sensor 64 is used. The control device 10 performs the same defrosting control as in any of the first to third embodiments based on the refrigerant temperature on the suction side of the compressor 30. Since the refrigerant temperature on the suction side of the compressor 30 is substantially equal to the refrigerant temperature on the outlet side of the air refrigerant heat exchanger 60, the present embodiment can provide the same effects as those of the first to third embodiments.

(Other embodiments)
In the above embodiment, the high-temperature and high-pressure refrigerant discharged from the compressor 30 is caused to flow into the air refrigerant heat exchanger 60 by stopping the circulation pump 74 and fully opening the expansion valve 50, for example. A hot gas bypass channel for allowing the high-temperature and high-pressure refrigerant to flow into the air refrigerant heat exchanger 60 may be separately provided. The hot gas bypass channel bypasses the water refrigerant heat exchanger 40 and the expansion valve 50 and is provided between the discharge side of the compressor 30 and the upstream side of the air refrigerant heat exchanger 60. The hot gas bypass channel is provided with an electromagnetic valve that opens and closes the channel. In this case, the control device 10 sets the electromagnetic valve to a closed state during normal boiling operation, and sets the opening of the expansion valve 50 to a low opening and sets the electromagnetic valve to an open state during defrosting operation. Thus, when the defrosting operation is started, the high-temperature and high-pressure refrigerant discharged from the compressor 30 flows into the air refrigerant heat exchanger 60 via the hot gas bypass flow path, and the defrosting of the air refrigerant heat exchanger 60 is performed. Is done.

  Moreover, in the said embodiment, although the expansion valve cycle provided with the expansion valve 50 was mentioned as an example as the heat pump cycle 20, it is applicable also to the ejector cycle provided with the ejector.

Further in the above embodiment uses CO ₂ as the refrigerant circulating through the heat pump cycle 20, may be a mixed refrigerant or other coolant such as R410.

  In the above-described embodiment, the heat pump type hot water supply apparatuses 1 and 4 are exemplified. However, the present invention can be applied to a heat pump type air conditioner and the like.

It is a figure which shows typically schematic structure of the heat pump apparatus and hot water supply apparatus in 1st Embodiment. It is a flowchart which shows the flow of defrost control. It is a graph which shows the change of the number of rotations of the compressor set up by a control device, when the compressor deceleration flag is set up in a 1st embodiment. It is a graph which shows the change of the number of rotations of the compressor set up by a control device, when the compressor deceleration flag is set up in a 2nd embodiment. It is a graph which shows the change of the number of rotations of the compressor set up by a control device, when the compressor deceleration flag is set up in a 3rd embodiment. It is a figure which shows typically schematic structure of the heat pump apparatus and hot water supply apparatus in 4th Embodiment.

Explanation of symbols

1, 4 Hot-water supply device 2, 5 Heat pump device 10 Control device (control unit)
20 Heat pump cycle 30 Compressor 40 Water refrigerant heat exchanger (high pressure side heat exchanger)
50 Expansion valve 60 Air refrigerant heat exchanger (low pressure side heat exchanger)
62 Outside air temperature sensors 63 and 64 Refrigerant temperature sensor 70 Hot water storage tank 72 Hot water supply pipe (hot water supply flow path)

Claims (5)

A heat pump cycle (20) including at least a compressor (30), a high-pressure side heat exchanger (40), and a low-pressure side heat exchanger (60), and circulating a refrigerant;
Refrigerant temperature sensors (63, 64) for detecting the refrigerant temperature of the refrigerant flowing out of the low pressure side heat exchanger (60);
An outside air temperature sensor (62) for detecting the outside air temperature of the outside air blown to the low pressure side heat exchanger (60) ;
A controller (10) for performing defrost control for defrosting frost adhering to the low pressure side heat exchanger (60),
The controller (10) sets the rotational speed of the compressor (30) to a first rotational speed (RCa) when performing the defrost control,
When the refrigerant temperature is equal to or higher than the second temperature (TFa),
When the outside air temperature is the first temperature (TGa) above is less than the previous SL said first rotational speed to the rotational speed of the compressor (30) from said (RCa) first rotational speed (RCa) Reduce to the second rotational speed (RCb),
When the outside air temperature is lower than the first temperature (TGa), the heat pump device maintains the rotation speed of the compressor (30) at the first rotation speed (RCa). The compressor (30) is provided so as to suck in refrigerant that has flowed out of the low-pressure side heat exchanger (60),
The heat pump device according to claim 1 , wherein the refrigerant temperature sensor (64) is provided on a suction side of the compressor (30). The heat pump apparatus according to claim 1 or 2, characterized in that carbon dioxide is used as refrigerant. The heat pump device according to any one of claims 1 to 3 , a hot water storage tank (70) for storing hot water heated by the heat pump device, and a hot water supply flow for supplying hot water in the hot water storage tank (70) to the outside A hot water supply device comprising a passage (72). A heat pump cycle (20) including at least a compressor (30), a high-pressure side heat exchanger (40), and a low-pressure side heat exchanger (60), and circulating a refrigerant;
A refrigerant temperature sensor (63) for detecting the refrigerant temperature of the refrigerant flowing out of the low-pressure side heat exchanger (60);
Frost adhering to the low pressure side heat exchanger (60) in the heat pump device (2) including an outside temperature sensor (62) for detecting the outside temperature of the outside air blown to the low pressure side heat exchanger (60) A control device for a heat pump device that performs defrost control for defrosting,
When performing the defrost control, the rotation speed of the compressor (30) is set to the first rotation speed (RCa),
When the refrigerant temperature is equal to or higher than the second temperature (TFa),
When the outside air temperature is the first temperature (TGa) above is less than the previous SL said first rotational speed to the rotational speed of the compressor (30) from said (RCa) first rotational speed (RCa) Reduce to the second rotational speed (RCb),
When the outside air temperature is lower than the first temperature (TGa), the compressor (30) maintains the rotational speed of the compressor (30) at the first rotational speed (RCa). .

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