JP6695033B2 - Heat pump device - Google Patents

Description

  The present invention relates to a technique for suppressing an increase in low-pressure side pressure of a heat pump device.

  2. Description of the Related Art Conventionally, as this type of heat pump device, there is known a heat pump device including two refrigeration circuits, an air conditioning refrigeration cycle and a hot water supply refrigeration cycle.

  The refrigeration cycle for air conditioning includes an air conditioning compressor, an outdoor heat exchanger, an outdoor heat exchanger opening / closing means, an outdoor heat exchanger throttling means, an indoor heat exchanger, an indoor heat exchanger opening / closing means, and an indoor heat exchanger throttling means. Are connected in series. The refrigerant-refrigerant heat exchanger and the hot-water supply heat source throttling means are connected in series. The refrigerant-refrigerant heat exchanger and the hot-water supply heat source throttle means are connected in parallel to the indoor heat exchanger, the indoor heat exchanger opening / closing means, and the indoor heat exchanger throttle means. The air conditioning refrigeration cycle circulates an air conditioning refrigerant.

  The hot-water supply refrigeration cycle is configured by connecting a hot-water supply compressor, a heat medium-refrigerant heat exchanger, a hot-water supply expansion means, and a refrigerant-refrigerant heat exchanger in series. The hot water supply refrigeration cycle circulates a hot water supply refrigerant.

  The refrigeration cycle for air conditioning and the refrigeration cycle for hot water supply are refrigerant-refrigerant heat exchangers, and are connected so as to exchange heat between the refrigerant for air conditioning and the refrigerant for hot water supply, thereby performing cooling or heating in the refrigeration cycle for air conditioning. It is possible to simultaneously perform the operation and the heating operation of the hot-water supply heat medium in the hot-water supply refrigeration cycle (see, for example, Patent Document 1).

  However, in the above conventional configuration, the condensation temperature of the air conditioning refrigeration cycle becomes high when the heating load is high in the air conditioning refrigeration cycle or when the cooling operation is performed under the condition that the outside air temperature is high. Therefore, the evaporation temperature of the hot-water supply refrigeration cycle in the refrigerant-refrigerant heat exchanger also rises, and the low-pressure side pressure rises. When a carbon dioxide refrigerant is used in the hot water supply refrigeration cycle, the low-pressure side pressure becomes equal to or higher than the critical pressure and becomes a supercritical refrigerant. When the supercritical refrigerant is sucked into the hot water supply compressor, there is a problem that the sealability of oil in the hot water supply compressor deteriorates, and the reliability of the compressor deteriorates.

International Publication No. 2009/098751

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat pump device capable of suppressing an increase in the low-pressure side pressure of a hot water supply refrigeration cycle.

In order to achieve the above object, a heat pump device according to the present invention is a hot water supply refrigeration system in which a first compressor, a first condenser, a first throttle means, and a first evaporator are annularly connected to circulate a first refrigerant. A first refrigeration circuit as a cycle, a second refrigeration circuit as an air conditioning refrigeration cycle that circulates a second refrigerant, and exchanges heat with the first refrigeration circuit in the first evaporator, and a control unit. .. The control section reduces the flow rate of the second refrigerant circulating in the second refrigeration circuit and reduces the opening degree of the first throttle means so that the low-pressure side pressure of the first refrigeration circuit becomes a predetermined value or less. It has a refrigeration circuit low pressure suppression mode.

  As a result, the flow rate of the second refrigerant decreases, the refrigerant density on the low pressure side of the first refrigeration circuit decreases, and the flow rate of the first refrigerant flowing through the first refrigeration circuit also decreases. Therefore, the amount of heat exchange from the second refrigerant to the first refrigerant in the evaporator is reduced. Therefore, the evaporation amount of the first refrigerant is reduced, and the low pressure side pressure of the first refrigeration circuit is lowered.

  According to the present invention, the pressure on the low pressure side of the first refrigeration circuit can be reduced, and the first refrigerant can be sucked into the first compressor at a pressure equal to or lower than the critical pressure of the first refrigerant. Thereby, the reliability of the first compressor can be improved.

  Further, by decreasing the pressure on the low pressure side of the first refrigeration circuit, the enthalpy difference of the first refrigerant in the evaporator can be increased. As a result, a high heating capacity can be output from the initial state of operation.

FIG. 1 is a refrigeration cycle diagram according to an embodiment of the present invention. FIG. 2 is a diagram for explaining the same operation. FIG. 3 is a diagram for explaining the same operation. FIG. 4 is a diagram for explaining the same operation. FIG. 5 is a diagram for explaining the same operation. FIG. 6 is a diagram showing a control flow. FIG. 7 is a diagram showing a control flow of another embodiment. FIG. 8 is a diagram showing a control flow of another embodiment.

  A heat pump device according to a first aspect of the present invention includes a first refrigeration circuit that connects a first compressor, a first condenser, a first throttle means, and a first evaporator in an annular shape, and circulates a first refrigerant, and a second refrigerant. And a second refrigerating circuit that heat-exchanges with the first refrigerating circuit in the first evaporator, and a control unit. The control unit reduces the flow rate of the second refrigerant circulating in the second refrigeration circuit so that the low-pressure side pressure of the first refrigeration circuit becomes equal to or lower than a predetermined value, and reduces the opening degree of the first throttle means. It has a circuit low voltage suppression mode.

  According to the first aspect, the flow rate of the second refrigerant decreases, the refrigerant density on the low pressure side of the first refrigeration circuit decreases, and the flow rate of the first refrigerant flowing through the first refrigeration circuit also decreases. Therefore, the amount of heat exchange from the second refrigerant to the first refrigerant in the evaporator is reduced. Therefore, the evaporation amount of the first refrigerant is reduced, and the low pressure side pressure of the first refrigeration circuit can be reduced.

  In the heat pump device according to the second aspect of the present invention, the second refrigeration circuit has an outdoor unit having a second compressor, an outdoor heat exchanger, and a second expansion means, an indoor unit having an indoor heat exchanger, and a first evaporator. And a circulation circuit for circulating the second refrigerant. The circulation circuit is provided with a third throttle means for controlling the circulation amount of the second refrigerant, and in the first refrigeration circuit low pressure suppression mode, the third refrigeration circuit is controlled so that the low pressure side pressure of the first refrigeration circuit becomes a predetermined value or less. The opening of the throttle means is reduced and the opening of the first throttle means is reduced.

  According to the second aspect, the flow rate of the second refrigerant decreases, the refrigerant density on the low pressure side of the first refrigeration circuit decreases, and the flow rate of the first refrigerant flowing through the first refrigeration circuit also decreases. Therefore, the amount of heat exchange from the second refrigerant to the first refrigerant in the evaporator is reduced. Therefore, the evaporation amount of the first refrigerant is reduced, and the low pressure side pressure of the first refrigeration circuit can be reduced.

  A heat pump device according to a third aspect of the present invention includes pressure detection means for detecting the low pressure side pressure of the first compressor. The control unit executes the first refrigeration circuit low pressure suppression mode when the low pressure side pressure becomes equal to or lower than a predetermined value.

  According to the third aspect of the invention, the pressure detecting means detects the low pressure side pressure of the first compressor and executes the first refrigeration circuit low pressure suppression mode when the low pressure side pressure becomes equal to or lower than a predetermined value. 1 The refrigeration circuit low pressure suppression mode can be accurately executed.

  Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited to this embodiment.

  FIG. 1 is a refrigeration cycle diagram showing an embodiment of a heat pump device of the present invention.

  The heat pump device shown in FIG. 1 includes two refrigerating circuits, a first refrigerating circuit 5 as a hot water supply refrigerating cycle and a second refrigerating circuit 15 as an air conditioning refrigerating cycle.

  The first refrigeration circuit is a circuit that constitutes the heat generation unit 40, and the hot water supply refrigerant (first refrigerant) is circulated. The second refrigeration circuit includes an outdoor unit 10, an indoor unit 30, and a circulation circuit 20 that is piped across the first refrigeration circuit 5, and an air-conditioning refrigerant (second refrigerant) is circulated. The circulation circuit 20 is a circuit that connects a gas pipe 25 and a liquid pipe 27, which will be described later, via the evaporator 4 (first evaporator) of the heat generation unit 40.

  As the hot-water supply refrigerant and the air-conditioning refrigerant, natural refrigerants such as carbon dioxide (CO2) are used in addition to CFC-based refrigerants such as R22, R410A, R407C, R32, and R134a. In particular, R407C, R134a and carbon dioxide (CO2), which are widely used for high temperature applications, are preferable as the hot water supply refrigerant.

  In this embodiment, two indoor units 30 and one heat generation unit 40 are connected to one outdoor unit 10, respectively. The refrigeration cycle configuration is not limited to that shown in FIG. For example, two or more outdoor units 10, one or three indoor units 30 and two or more heat generation units 40 can be connected in parallel. In the present embodiment, the control unit 116 is provided as a control unit for the first refrigeration circuit 5 and the second refrigeration circuit 15.

  The heat generation unit 40 that constitutes the first refrigeration circuit includes a hot water supply compressor (first compressor) 1 and a condenser (first condenser) that exchanges heat with a hot water supply refrigerant and a heat medium containing water as a main component. 2, a throttle means (first throttle means) 3, and an evaporator (first evaporator) 4 for exchanging heat between a refrigerant for air conditioning and a refrigerant for hot water supply which are supplied from a gas pipe 25 described later by refrigerant pipes. It is configured to be connected in series to circulate the hot water supply refrigerant. The evaporator 4 is a plate-type heat exchanger.

  A first refrigeration circuit low pressure detection means (pressure detection means) 6 for detecting the pressure of the hot water supply refrigerant sucked into the hot water supply compressor 1 is provided between the hot water supply compressor 1 and the evaporator 4. There is.

  The condenser (first condenser) 2 is connected to a pipe 2a for a heat medium that exchanges heat with the hot water supply refrigerant, and the pipe 2a is connected to a circulation pump 2b.

  Note that tap water is generally used as the heat medium, but in the case of a cold region, an antifreeze solution obtained by dissolving a predetermined amount of ethylene glycol or alcohol in water may be used.

  The heat medium boiled up to 70 to 90 ° C. in the condenser 2 is stored in a hot water storage tank (not shown). When the heating medium is drinking water, it is used directly for hot water supply. On the other hand, when the heat medium is not drinking water such as antifreeze, it is supplied to a radiator or the like installed in the room and used for heating, or heat is transferred to drinking water in a hot water storage tank and used for hot water supply.

  The second refrigeration circuit will be described.

  The outdoor unit 10 and the indoor unit 30 include a gas pipe 25 through which a high-temperature and high-pressure gasified air-conditioning refrigerant flows, a suction pipe 26 through which a low-pressure air-conditioning refrigerant flows, and a liquid pipe 27 through which a high-pressure liquefied air-conditioning refrigerant flows. Connected with and. When there are two indoor units 30 as shown in FIG. 1, the indoor units 30 are connected in parallel to the three pipes. On the other hand, the outdoor unit 10 and the heat generation unit 40 are connected in parallel to the pipes like the indoor unit 30, but are connected by two pipes of a gas pipe 25 and a liquid pipe 27.

  The outdoor unit 10 includes an air conditioning compressor (second compressor) 7, an outdoor heat exchanger 11, an outdoor gas pipe opening / closing means 12b disposed at one inlet of the outdoor heat exchanger 11, and an outdoor suction pipe opening / closing. Means 12a and outdoor heat exchanger throttling means (second throttling means) 13 arranged at the other inlet of the outdoor heat exchanger 11 are provided.

  The air conditioning compressor 7 compresses the air conditioning refrigerant. The outdoor heat exchanger 11 is configured to exchange heat between the air sent by the outdoor blower fan 17 and the air conditioning refrigerant. As the outdoor heat exchanger 11, a fin-tube type or microtube type heat exchanger is generally applied. The outdoor gas pipe opening / closing means 12b controls the flow rate of the air-conditioning refrigerant in the gas pipe 25. The outdoor suction pipe opening / closing means 12 a controls the flow rate of the air conditioning refrigerant in the suction pipe 26. The outdoor heat exchanger throttling means 13 adjusts the flow rate of the air-conditioning refrigerant supplied to the outdoor heat exchanger 11.

  An accumulator 12 that supplies a gas refrigerant to the air conditioning compressor 7 is connected to the suction side of the air conditioning compressor 7. An oil separator 16 that separates refrigerating machine oil contained in the discharged gas-state refrigerant for air conditioning is connected to the discharge side of the air conditioning compressor 7. The refrigeration oil separated by the oil separator 16 is returned to the air conditioning compressor 7 through the oil return pipe 114. The communication of the oil return pipe 114 is controlled by opening and closing the oil return pipe opening / closing valve 115.

  The indoor unit 30 includes indoor heat exchangers 8a and 8b, indoor gas pipe opening / closing means 9b and 9d and indoor suction pipe opening / closing means 9a and 9c, which are arranged at one inlet of the indoor heat exchangers 8a and 8b. The indoor heat exchanger throttling means 10a and 10b arranged at the other inlets of the heat exchangers 8a and 8b. The indoor heat exchangers 8a and 8b are configured such that the air sent by the indoor blower fan 32 and the air-conditioning refrigerant exchange heat with each other. Generally, the fin-tube type or the microtube type heat exchanger is used. Is applied. The indoor gas pipe opening / closing means 9b and 9d control whether or not the air-conditioning refrigerant flows through the gas pipe 25. The indoor suction pipe opening / closing means 9a, 9c control whether or not the air-conditioning refrigerant flows through the suction pipe 26. The indoor heat exchanger throttling means 10a, 10b adjust the flow rate of the air conditioning refrigerant supplied to the indoor heat exchangers 8a, 8b.

  The discharge side of the air conditioning compressor 7 is connected to one end of the outdoor heat exchanger 11 by a refrigerant pipe via the outdoor gas pipe opening / closing means 19. The liquid pipe 27 connected to the other end of the outdoor heat exchanger 11 branches outside the outdoor unit 10 via the outdoor heat exchanger throttling means 13, and one of the branched liquid pipes 27 is connected in parallel. In the indoor unit 30, the refrigerant is connected to one end of each of the indoor heat exchangers 8a and 8b through the refrigerant heat pipes 10a and 10b.

  The other ends of the indoor heat exchangers 8a and 8b are connected by refrigerant pipes branched in two directions, one is connected to the gas pipe 25 through the indoor gas pipe opening / closing means 9b and 9d, and the other is open / close the indoor suction pipe. It is connected to the suction pipe 26 via means 9a, 9c.

  The other of the branched liquid pipes 27 is connected to one end of the evaporator 4 via the evaporator throttle means 14 (third throttle means). A gas pipe 25 is connected to the other end of the evaporator 4.

  The operation and action will be described below.

  First, a case where the indoor heat exchangers 8a and 8b are used as condensers to perform the heating operation of the second refrigeration circuit 15 and also the first refrigeration circuit 5 will be described. As shown in FIG. 2, the second refrigerant discharged from the air conditioning compressor 7 flows into the indoor heat exchangers 8a and 8b through the indoor gas pipe opening / closing means 9b and 9d in the open state, and becomes the indoor air. Dissipate heat. In the first refrigeration circuit 5, the first refrigerant discharged from the hot water supply compressor 1 radiates heat in the condenser 2, is squeezed by the expansion means 3 and flows into the evaporator 4, and absorbs heat from the second refrigerant. Is sucked into the hot water supply compressor 1.

  Then, the second refrigerant absorbed in the first refrigerant in the evaporator 4 and the second refrigerant flowing out from the indoor heat exchangers 8a and 8b are the evaporator throttle means 14 and the indoor heat exchanger throttle means 10a. Merge after passing through 10b with almost no restriction. The combined second refrigerant is throttled by the outdoor heat exchanger throttling means 13 and flows into the outdoor heat exchanger 11. The second refrigerant flowing into the outdoor heat exchanger 11 absorbs heat from the outdoor air, passes through the outdoor suction pipe opening / closing means 12a in the open state, and is sucked into the air conditioning compressor 7.

  The indoor suction pipe opening / closing means 9a, 9c and the outdoor gas pipe opening / closing means 12b are closed so that the second refrigerant does not flow.

  Next, a case will be described in which the indoor heat exchangers 8a and 8b are used as evaporators to perform the cooling operation of the second refrigeration circuit 15 and also operate the first refrigeration circuit 5. As shown in FIG. 3, the second refrigerant discharged from the air conditioning compressor 7 flows into the outdoor heat exchanger 11 through the open outdoor gas pipe opening / closing means 12b and radiates heat to the outdoor air. In the first refrigeration circuit 5, as in the heating operation of the second refrigeration circuit 15, the first refrigerant discharged from the hot water supply compressor 1 radiates heat in the condenser 2 and is squeezed by the throttle means 3 to be evaporated. Flows in, is absorbed by the second refrigerant, and is sucked into the hot water supply compressor 1.

  Then, the second refrigerant that has absorbed the first refrigerant in the evaporator 4 and the second refrigerant that has flowed out of the outdoor heat exchanger 11 pass through the evaporator throttle means 14 and the outdoor heat exchanger throttle means 13. It passes without being throttled, is throttled by the indoor heat exchanger throttling means 10a, 10b, flows into the indoor heat exchangers 8a, 8b, and absorbs heat from the indoor air. The second refrigerant that has exchanged heat with the indoor heat exchange air 8a, 8b is sucked into the air conditioning compressor 7 through the indoor suction pipe opening / closing means 9a, 9c in the open state. The indoor gas pipe opening / closing means 9b and 9d and the outdoor suction pipe opening / closing means 12a are closed so that the second refrigerant does not flow.

  Further, a case will be described in which the indoor heat exchanger 8a is used as a condenser and the indoor heat exchanger 8b is used as an evaporator to perform the cooling / heating simultaneous operation of the second refrigeration circuit 15 and also operate the first refrigeration circuit 5. As shown in FIG. 4, the second refrigerant discharged from the air conditioning compressor 7 flows into the indoor heat exchanger 8a through the indoor gas pipe opening / closing means 9b in the open state, and radiates heat to indoor air. In the first refrigeration circuit 5, the first refrigerant discharged from the hot water supply compressor 1 radiates heat in the condenser 2, is squeezed by the expansion means 3 and flows into the evaporator 4, and absorbs heat from the second refrigerant. Is sucked into the hot water supply compressor 1.

  Then, the second refrigerant that has absorbed the first refrigerant in the evaporator 4 and the second refrigerant that has flowed out of the indoor heat exchanger 8a substantially pass through the evaporator throttle means 14 and the indoor heat exchanger throttle means 10a. It passes without being throttled, and is throttled by the indoor heat exchanger throttling means 10b and the outdoor heat exchanger throttling means 13 and flows into the indoor heat exchanger 8b and the outdoor heat exchanger 11. The second refrigerant flowing into the indoor heat exchanger 8b and the outdoor heat exchanger 11 absorbs heat from the indoor air and the outdoor air, and the indoor suction pipe opening / closing means 9c and the outdoor suction pipe opening / closing means 12a are in an open state. And is sucked into the air conditioning compressor 7. In this case, the indoor suction pipe opening / closing means 9a, the indoor gas pipe opening / closing means 9d, and the outdoor gas pipe opening / closing means 12b are closed so that the second refrigerant does not flow.

  A case will be described in which the indoor heat exchanger 8a is used as an evaporator and the indoor heat exchanger 8b is used as a condenser to perform the cooling / heating simultaneous operation of the second refrigeration circuit and also the first refrigeration circuit 5. As shown in FIG. 5, the indoor suction pipe opening / closing means 9a and the indoor gas pipe opening / closing means 9d are in the open state, and the indoor gas pipe opening / closing means 9b and the indoor suction pipe opening / closing means 9c are in the closed state. Operate without changing the opening / closing of the exchange opening / closing means.

  In the above operating state, when the second refrigeration circuit 15 requires a large amount of heat radiation to the indoor air in the heating operation (for example, the indoor temperature is 5 ° C. and the set temperature is 30 ° C.), or the cooling operation is performed. When the temperature of the outdoor air is high (for example, 40 ° C.) and the temperature of the second refrigerant flowing into the outdoor heat exchanger 11 must be equal to or higher than the temperature of the outdoor air, the high pressure side pressure of the second refrigeration circuit 15 becomes high. .. Therefore, the pressure of the second refrigerant flowing into the evaporator 4 also becomes high, so that the condensation temperature becomes high and the amount of heat exchange from the second refrigerant to the first refrigerant increases. As a result, the pressure on the low pressure side of the first refrigeration circuit 5 increases.

  Particularly, when the first refrigerant is carbon dioxide (CO2), the critical point (31.1 ° C, 7.4 MPa) is low, and when the condensation temperature of the second refrigeration circuit 15 becomes high as described above, the first refrigeration circuit The low-pressure side of 5 may be sucked into the hot-water supply compressor 1 in a supercritical state. Then, when it becomes supercritical refrigerant and is taken into the hot water supply compressor 1, the sealability of the oil in the hot water supply compressor 1 deteriorates, and the reliability of the hot water supply compressor 1 decreases.

  In the present embodiment, as shown in FIG. 6, the control unit 116 determines whether the pressure Ps1 detected by the first refrigeration circuit low pressure detection means 6 is equal to or higher than a predetermined value α (for example, 5.5 Mps) (S1). ). If the pressure Ps1 is equal to or higher than the predetermined value α, the first refrigeration circuit low pressure suppression mode is set. When the first refrigeration circuit low pressure suppression mode is set, the valve opening degree of the evaporator throttle means 14 is reduced and the second refrigeration circuit 15 is circulated so that the low pressure side pressure Ps1 becomes equal to or lower than the predetermined value α. The flow rates of the two refrigerants are reduced and the valve opening degree of the first throttle means 3 is reduced (S2).

  When the valve opening degree of the first throttle means 3 decreases, the refrigerant density on the low pressure side of the first refrigeration circuit 5 decreases, and the flow rate of the first refrigerant flowing through the first refrigeration circuit 5 also decreases. Therefore, the amount of heat exchange from the second refrigerant to the first refrigerant in the evaporator 4 decreases. Therefore, the evaporation amount of the first refrigerant is reduced, and the low pressure side pressure of the first refrigeration circuit 5 is reduced.

  Further, since the heat medium in the condenser 2 has a large heat capacity and a low temperature (for example, water at 10 ° C.), the condensation temperature of the condenser 2 does not rise in the initial operation state of the first refrigeration circuit 5, The pressure on the low pressure side of the first refrigeration circuit 5 of the evaporator 4 is high and the heating capacity is low.

  In the initial operation state of the first refrigerating circuit 5, the low-pressure side pressure of the first refrigerating circuit 5 decreases, so that the enthalpy difference of the first refrigerant in the evaporator 4 can be increased. As a result, a high heating capacity can be output from the initial state of operation.

  Further, when the superheat degree of the first refrigerant drawn into the hot water supply compressor 1 is high, the low-pressure side pressure of the first refrigeration circuit 5 is reduced, so that the superheat degree of the first refrigerant at the outlet of the evaporator 4 is increased. Can be made smaller. As a result, it is possible to suppress the efficiency decrease due to the increase in the degree of superheat of the first refrigerant drawn into the hot water supply compressor 1 and the excessive temperature rise of the first refrigerant discharged from the hot water supply compressor 1.

  Further, in the present embodiment, the opening degree of the evaporator throttle means 14 is reduced as a means for reducing the flow rate of the second refrigerant in the second refrigeration circuit 15, but the invention is not limited to this. To reduce the flow rate of the second refrigerant in the second refrigeration circuit 15 by reducing the transport amount of the air conditioning compressor 7, for example, lowering the frequency of the air conditioning compressor 7 (S2), and reducing the evaporator throttle means 14. It is also possible to reduce the opening degree and the transport amount of the air conditioning compressor 7 to reduce the flow rate of the second refrigerant in the second refrigeration circuit 15.

  Further, in the present embodiment, the first refrigeration circuit low pressure detection means 6 used as a means for detecting the low pressure side pressure of the first refrigeration circuit 5 is arranged between the hot water supply compressor 1 and the evaporator 4. However, it is also possible to arrange it between the throttle means 3 and the evaporator 4.

  Further, in the present embodiment, the evaporator 4 is composed of a plate type heat exchanger. By using the evaporator 4 as a plate-type heat exchanger, it is possible to reduce the amount of the first refrigerant held on the low pressure side and suppress a rapid increase in the high pressure side pressure due to an increase in the transport amount to the high pressure side.

  In addition, in the present embodiment, when the superheat degree of the first refrigerant drawn into the hot water supply compressor 1 is high, the pressure on the low pressure side of the first refrigeration circuit 5 is reduced to reduce the first refrigerant at the outlet of the evaporator 4. Of the first refrigerant can be reduced, and the efficiency decrease due to the increase of the superheat degree of the first refrigerant drawn into the hot water supply compressor 1 and the excessive temperature rise of the first refrigerant discharged from the hot water supply compressor 1 can be suppressed. be able to.

  In the present embodiment, the first refrigeration circuit low pressure detection means 6 is used as the pressure detection means for detecting the low pressure side pressure of the first refrigeration circuit 5, but as shown in FIG. You may use the evaporator inlet temperature detection means 117 which detects temperature.

  In this case, the control flow is shown in FIG. In the control flow of FIG. 7, the determination of (S11) is different when compared with the control flow of FIG. The other steps are the same as those in the control flow of FIG.

  That is, it is determined whether the temperature Tein detected by the evaporator inlet temperature detecting means 117 is, for example, 20 ° C. or higher (S11).

  Then, for example, when the temperature is 20 ° C. or higher, the control is performed so as to shift to step S2, similarly to the control flow of FIG.

  Therefore, the amount of heat exchange from the second refrigerant to the first refrigerant in the evaporator 4 decreases, the evaporation amount of the first refrigerant decreases, and the low-pressure side pressure of the first refrigeration circuit 5 decreases.

  Therefore, the first refrigerant can be drawn into the compressor at a critical pressure or less, and the reliability of the compressor can be improved at a lower cost.

  Further, in the present embodiment, as shown in FIG. 1, an air conditioning compressor discharge pressure detecting means 118 for detecting the discharge pressure of the air conditioning compressor 7 may be used as another form.

  In this case, the control flow is shown in FIG. In the control flow of FIG. 8, the determination of (S12) is different when compared with the control flow of FIG. The other steps are the same as those in the control flow of FIG.

  That is, it is determined whether or not the pressure detected by the air-conditioning compressor discharge pressure detecting means 118 is, for example, 3.7 MPa or more (S11).

  Then, for example, in the case of 3.7 Mbps, the control is performed so as to shift to step S2, similarly to the control flow of FIG.

  According to this, the pressure on the low pressure side of the first refrigeration circuit 5 decreases regardless of the temperature on the heat absorption side of the evaporator 4. Therefore, the low-pressure side pressure of the first refrigeration circuit 5 can be reduced to the critical pressure or less and sucked into the hot water supply compressor 1 regardless of the temperature on the heat absorption side of the evaporator 4, and the compressor of a simpler configuration can be used. The reliability can be improved.

  The present invention has been described above based on the present embodiment, but the present invention is not limited to this embodiment. Since the embodiments of the present invention are merely illustrated, the present invention can be arbitrarily modified and applied without departing from the spirit of the present invention.

  As described above, the heat pump device according to the present invention can suppress an increase in the low-pressure side pressure of the hot water supply refrigeration cycle, and can be applied to a heat pump device having a hot water supply function or a heating function.

Compressor for hot water supply (first compressor)
2 Condenser (first condenser)
3 Drawing means (first drawing means)
4 Evaporator (first evaporator)
5 Refrigeration cycle for hot water supply (first refrigeration circuit)
6 First refrigeration circuit low pressure detection means (pressure detection means)
7 Air-conditioning compressor (second compressor)
10 outdoor unit 11 outdoor heat exchanger 13 outdoor heat exchanger throttling means (second throttling means)
14 Evaporator throttle means (third throttle means)
15 Air conditioning refrigeration cycle (second refrigeration circuit)
116 control unit 20 circulation circuit 30 indoor unit

Claims (3)

A first refrigeration circuit as a hot water supply refrigeration cycle in which a first compressor, a first condenser, a first throttle means, and a first evaporator are annularly connected, and a first refrigerant is circulated;
A second refrigeration circuit as an air conditioning refrigeration cycle in which a second refrigerant is circulated and heat is exchanged with the first refrigeration circuit in the first evaporator;
And a control unit,
The control unit reduces the flow rate of the second refrigerant circulating in the second refrigeration circuit so that the low-pressure side pressure of the first refrigeration circuit becomes a predetermined value or less, and reduces the opening degree of the first throttle means. A heat pump device having a first refrigeration circuit low-pressure suppression mode to perform. The second refrigeration circuit circulates the second refrigerant through the second compressor, the outdoor heat exchanger, the outdoor unit having the second expansion means, the indoor unit having the indoor heat exchanger, and the first evaporator. And a circulation circuit,
The circulation circuit is provided with a third throttle means for controlling the circulation amount of the second refrigerant,
In the first refrigeration circuit low pressure suppression mode, the opening degree of the third throttle means is decreased and the opening degree of the first throttle means is decreased so that the low pressure side pressure of the first refrigeration circuit becomes a predetermined value or less. The heat pump device according to claim 1, which is reduced in size. The pressure detecting means for detecting the low pressure side pressure of the first compressor is provided, and the control unit executes the first refrigeration circuit low pressure suppression mode when the low pressure side pressure becomes equal to or lower than a predetermined value. The heat pump device according to item 2.

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