JP2013096661A - Heat pump device and heat pump water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat pump device capable of suppressing the amount of liquid returning to a compressor without using a refrigerant container while unfreezing frost deposited on a bottom of a heat sink, and to provide a heat pump water heater.SOLUTION: A heat pump device includes: a main circuit 10 having an air heat exchanger 5 in which a compressor 1, a water heat exchanger 2, an expansion valve 4, and an air heat exchanger 5 are connected in order by a refrigerant pipe, and exchanging heat between a high-pressure refrigerant on an intake side of the expansion valve 4 and a low-tempreature refrigerant on an outlet side of the air heat exchanger 5; a main defrosting circuit 20 guiding the high-temperature refrigerant discharged from the compressor 1 to the intake of a low/high-pressure heat exchanger 3 in a state of a higher temperature than that in normal operation by reducing the heat radiation of the water heat exchanger 2; and an auxiliary defrosting circuit 30 branched from a clearance between the compressor 1 and the water heat exchanger 2 of the main circuit 10, and joined to an intake side of the air heat exchanger 5 through an auxiliary-side on/off-valve 30a and a refrigerant pipe of a bottom stage forming a flow passage independent of the main circuit 10 among refrigerant pipes of a plurality of stages of the air heat exchanger 5.

Description

  The present invention relates to a heat pump device and a heat pump water heater.

  Generally, a heat pump device used for hot water supply or air conditioning includes a refrigeration cycle in which a compressor, a radiator, an expansion valve, and a heat absorber are sequentially connected by a refrigerant pipe. In a heat pump device that uses the atmosphere as a heat source for a heat absorber, in order to improve the efficiency of the refrigeration cycle, it is possible to perform a defrosting operation of frost attached to the heat absorber (hereinafter referred to as an air heat exchanger). Often has become. Various proposals have been made to improve the efficiency of the defrosting operation.

  However, when the frost adhering to the air heat exchanger melts during the defrosting operation, some of the frost slides down and accumulates at the bottom of the air heat exchanger, or low-temperature melted water Similarly, it may accumulate in the lowermost part, and frost or the like accumulated in the lowermost part may remain undissolved.

  In order to prevent this, conventionally, a bypass pipe branched from between the compressor and the radiator is passed below the lowermost refrigerant pipe of the air heat exchanger, and is connected to the outlet side of the air heat exchanger. A combined refrigeration cycle apparatus has been proposed (see, for example, Patent Document 1). In this refrigeration cycle apparatus, the high-temperature gas refrigerant between the compressor and the radiator is passed through the lowest stage of the air heat exchanger by the bypass pipe so as to melt the frost accumulated at the lowermost part of the air heat exchanger. I have to.

  In the technique of Patent Document 1, the high-temperature gas refrigerant is cooled when it passes through the air heat exchanger by the bypass pipe, becomes a liquid refrigerant, and merges on the outlet side of the air heat exchanger with the refrigerant that has flowed out of the air heat exchanger. Then head to the compressor. If the liquid refrigerant directed to the compressor is sucked into the compressor as it is, so-called liquid return occurs, and in order to prevent this, an accumulator is provided on the suction side of the compressor.

JP 2008-138921 A (page 12, FIG. 1)

  In the conventional refrigeration cycle apparatus, by providing a bypass pipe through which high-temperature gas refrigerant flows at the bottom of the air heat exchanger, frost accumulated at the bottom of the air heat exchanger can be melted, while condensing in the bypass pipe Therefore, a refrigerant container such as an accumulator for storing the liquid refrigerant is required, which increases the cost.

  The present invention has been made to solve the above-described problems, and it is possible to melt the frost accumulated at the lowermost portion of the heat absorber, while reducing the amount of liquid returned to the compressor without using a refrigerant container. It aims at providing the heat pump apparatus and heat pump water heater which can be suppressed.

  In the heat pump device according to the present invention, a compressor, a radiator, a decompressor, and a heat absorber are sequentially connected by refrigerant piping, and a high-pressure refrigerant on the inlet side of the decompressor and a low-pressure refrigerant on the outlet side of the heat absorber are connected. Main circuit with high / low pressure heat exchanger for heat exchange and high temperature / low pressure heat exchanger inlet with high temperature refrigerant discharged from compressor with lower temperature than normal operation by reducing heat dissipation in radiator The main defrosting circuit for leading to the main circuit, the compressor and the radiator of the main circuit are branched from, and the auxiliary side on-off valve and the independent flow separate from the main circuit among the multi-stage refrigerant pipes of the heat absorber And an auxiliary defrosting circuit that merges with the inlet side of the heat absorber via the lowermost refrigerant pipe forming the path.

  According to the present invention, the refrigerant that has become liquid refrigerant and has flowed out of the auxiliary defrost circuit by heat exchange with frost can flow into the heat absorber and be stored in the heat absorber. In addition, since the amount of heat exchange in the high and low pressure heat exchanger can be increased by the main defrosting circuit, the refrigerant flowing out of the heat absorber can be sufficiently heated. As a result, the amount of liquid return to the compressor can be suppressed without generating excess refrigerant, that is, without using a refrigerant container. Moreover, the frost deposited on the lowest part of a heat absorber can be melt | dissolved by heating the lowest part of a heat absorber by an auxiliary defrost circuit.

It is a schematic block diagram which shows the whole structure of the heat pump water heater to which the heat pump apparatus in one embodiment of this invention is applied. It is an explanatory schematic diagram of the state where the 2nd bypass pipe 32 has been arranged in the lowest step part of the air heat exchanger 5 of FIG. It is a timing chart which shows the control timing of each apparatus in each operation mode. It is a Mollier diagram (PH diagram) showing a refrigerant state of main circuit 10 during hot water storage operation. It is a Mollier diagram (PH diagram) showing refrigerant states of the main circuit 10, the main defrost circuit 20, and the auxiliary defrost circuit 30 during the defrost preparation operation. It is explanatory drawing which shows an example of control of the rotation speed of the compressor 1, and the opening degree of the expansion valve 4. It is a figure which shows the example of control in a defrost preparation operation, and shows the example which made it increase in steps, after reducing the rotation speed of the compressor 1 stepwise and once reducing the opening degree of the expansion valve 4. FIG. It is a Mollier diagram (PH diagram) showing refrigerant states of the main circuit 10, the main defrost circuit 20, and the auxiliary defrost circuit 30 during the defrost main operation. It is a flowchart which shows the flow of the switching process of each driving | operation in the heat pump water heater 100 of FIG.

Hereinafter, a heat pump device according to an embodiment of the present invention will be described. In the embodiment, an example in which the heat pump device is applied to a heat pump water heater will be described. Further, it is assumed that carbon dioxide (hereinafter simply referred to as CO ₂ ) is used as the refrigerant.

FIG. 1 is a schematic configuration diagram illustrating an overall configuration of a heat pump water heater to which a heat pump device according to an embodiment of the present invention is applied. In FIG. 1 and the drawings to be described later, the same reference numerals denote the same or corresponding parts, which are common throughout the entire specification.
The heat pump water heater 100 is roughly provided with a heat pump device 60 and a hot water storage device 70. The heat pump device 60 includes a refrigerant circuit that circulates the refrigerant, and has a function as a heating unit that heats water in a hot water storage tank 71 (to be described later) of the hot water storage device 70 and boils it to hot water using the refrigerant circulating in the refrigerant circuit. Yes.

<Heat pump device>
Hereinafter, the configuration of the heat pump device 60 will be described.
The heat pump device 60 includes a compressor 1, an oil separator 1a, a water heat exchanger 2 as a radiator, a high and low pressure heat exchanger 3, an expansion valve 4 as a decompression device, and air heat as a heat absorber. The main circuit 10 of the refrigerant circuit connected to the exchanger 5 by the refrigerant pipe 11 is provided. The main circuit 10 is generally called a heat pump cycle, and transfers heat by circulating a refrigerant between the devices.

  The compressor 1 compresses a refrigerant into a high-temperature / high-pressure refrigerant. The water heat exchanger 2 increases the temperature of the water by exchanging heat between the high-temperature and high-pressure refrigerant discharged from the compressor 1 and hot water. That is, the water heat exchanger 2 is for boiling water into hot water. The expansion valve 4 is for reducing the pressure of the refrigerant after boiling water into a low-temperature / low-pressure refrigerant.

  The high-low pressure heat exchanger 3 exchanges heat between the high-pressure refrigerant on the inlet side of the expansion valve 4 and the low-pressure refrigerant at the outlet of the air heat exchanger 5. Hereinafter, in the high-low pressure heat exchanger 3, a pipe on the side through which the high-temperature / high-pressure refrigerant passes may be distinguished as a high-pressure pipe 3a, and a pipe on the side through which the low-temperature / low-pressure refrigerant passes may be distinguished as a low-pressure pipe 3b.

  The air heat exchanger 5 absorbs heat by evaporating the refrigerant supplied from the expansion valve 4 with the outside air supplied from a fan 5a as a blower arranged in the vicinity of the air heat exchanger 5, and evaporates the refrigerant. is there.

(Main defrosting circuit 20)
The heat pump device 60 branches from the oil separator 1 a of the main circuit 10 and the water heat exchanger 2 at the branch portion 21, and joins the junction 23 between the water heat exchanger 2 and the high and low pressure heat exchanger 3. The first bypass pipe 22 that joins the main circuit 10 is provided. The first bypass pipe 22 is provided with a main-side on-off valve 20a. By controlling the opening of the main-side on-off valve 20a, the high-temperature refrigerant from the compressor 1 flows directly from the first bypass pipe 22 into the high-low pressure heat exchanger 3 without going through the water heat exchanger 2, and the air heat The defrosting operation of the exchanger 5 is performed. That is, the main defrosting circuit 20 is formed by the refrigerant flowing into the first bypass pipe 22.

  The main defrosting circuit 20 guides the refrigerant discharged from the compressor 1 to the inlet of the high / low pressure heat exchanger 3 in a state where the temperature is higher than that during normal operation (hot water storage operation described later). The amount of heat exchange is increased to prevent liquid return during the defrosting operation.

  For the main-side on-off valve 20a, a main-side on-off valve 20a having a configuration in which the refrigerant flow rate flowing into the main-side on-off valve 20a is larger than the refrigerant flow rate flowing into the water heat exchanger 2 is selected. As a result, the flow rate of refrigerant flowing into the water heat exchanger 2 is reduced, and the amount of heat dissipated in the water heat exchanger 2 (heat exchange amount) can be reduced. Therefore, the high-temperature and high-pressure refrigerant discharged from the compressor 1 is reduced. The high-low pressure heat exchanger 3 can be allowed to flow while maintaining the high temperature and high pressure.

(Auxiliary defrost circuit 30)
The heat pump device 60 branches from the oil separator 1 a of the main circuit 10 and the water heat exchanger 2 at the branching portion 31, and passes through the lowermost stage portion of the air heat exchanger 5 to expand the expansion valve 4 of the main circuit 10. And a second bypass pipe 32 that joins the main circuit 10 at a junction 33 between the air heat exchanger 5 and the air heat exchanger 5. The second bypass pipe 32 is provided with an auxiliary side on-off valve 30a. This auxiliary-side on-off valve 30a is controlled to open, and the high-temperature refrigerant from the compressor 1 flows into the second bypass pipe 32 and passes through the lowermost stage of the air heat exchanger 5, thereby allowing air heat exchange during defrosting operation. The frost and low-temperature water that have flowed down from the upper part of the vessel 5 are reheated so that they are not frozen at the lowest stage of the air heat exchanger 5. That is, the auxiliary defrost circuit 30 is formed by the refrigerant flowing into the second bypass pipe 32.

FIG. 2 is an explanatory schematic view of a state in which the second bypass pipe 32 is arranged at the lowermost stage portion of the air heat exchanger 5 of FIG. 1, FIG. 2 (a) is a perspective view of the heat pump device, and FIG. 2A is a cross-sectional view taken along the line AA, and FIG. 2C is a perspective view of the air heat exchanger 5. The arrow in FIG.2 (c) has shown the flow direction of the refrigerant | coolant.
Although not shown in detail in FIG. 2, the air heat exchanger 5 has refrigerant pipes arranged in a plurality of stages in the vertical direction, and a part of the main circuit 10 is formed by a plurality of refrigerant pipes excluding the lowest stage. It is configured. That is, a flow path is formed in which the refrigerant flowing in from the expansion valve 4 flows out to the high-low pressure heat exchanger 3 after sequentially passing through a plurality of stages of refrigerant piping. The lowermost refrigerant pipe forms an independent flow path different from the flow path of the main circuit 10, and a part of the second bypass pipe 32 of the auxiliary defrost circuit 30 is formed by the lowermost refrigerant pipe. Is configured.

(Oil return bypass circuit 40)
The heat pump device 60 includes an oil return bypass circuit 40 that connects the high-low pressure heat exchanger 3 and the compressor 1 to return the oil separated by the oil separator 1 a of the main circuit 10 to the compressor 1. . During operation of the heat pump water heater 100, oil contained in the refrigerant discharged from the compressor 1 is always returned to the compressor 1 by the oil return bypass circuit 40. Although not shown in detail in FIG. 1, in the oil return bypass circuit 40, the flow rate is controlled and returned to the compressor 1.

(Heating auxiliary circuit 50)
The heat pump device 60 includes a third bypass pipe 52 connected in parallel to the oil return bypass circuit 40. The oil return bypass circuit 40 is a circuit that suppresses the oil return amount of the oil discharged from the compressor 1 and returns it to the compressor 1. However, the third bypass pipe 52 has a role of actively returning the oil. Therefore, the third bypass pipe 52 is formed with a flow resistance smaller than the oil return bypass circuit 40.

  The third bypass pipe 52 is provided with an oil return side on-off valve 50a. By controlling the opening of the oil return side on-off valve 50a, the oil separated by the oil separator 1a in the oil return bypass circuit 40 flows into the third bypass pipe 52, flows out of the high / low pressure heat exchanger 3 and is compressed. The low-temperature refrigerant that goes to the machine 1 is joined and heated, and flows into the compressor 1. That is, the heating auxiliary circuit 50 is formed by the oil flowing into the third bypass pipe 52. Although FIG. 1 shows a configuration in which the third bypass pipe 52 is connected in parallel to the oil return bypass circuit 40 and the merge portion 51 is provided on the oil return bypass circuit 40, the merge portion 51 is provided with the oil return bypass circuit. Not only on the circuit 40, it may be between the low pressure pipe 3 b of the high and low pressure heat exchanger 3 and the compressor 1.

(Sensor)
The heat pump device 60 includes an evaporating temperature detecting device 7a for detecting an inlet refrigerant temperature (evaporating temperature (Tei)) of the air heat exchanger 5, and an outside air temperature for detecting the ambient air temperature of the air heat exchanger 5. A detection device 7b is provided. Furthermore, the heat pump device 60 controls each device in each operation shown in FIG. 3 to be described later based on information from the evaporation temperature detection device 7a and the outside air temperature detection device 7b, and each operation shown in FIG. 9 to be described later. A control device 61 that performs switching control is provided. The control device 61 may be configured by a microcomputer or the like that can control the entire heat pump water heater 100.

  The evaporation temperature detecting device 7a and the outside air temperature detecting device 7b are not particularly limited as long as they can detect the evaporation temperature (Tei) and the outside air temperature, respectively. For example, a temperature sensor such as a thermistor or a thermometer may be used. Here, only the evaporation temperature detection device 7a and the outside air temperature detection device 7b are shown, but a humidity detection device for detecting the ambient air humidity, a pressure detection device for detecting the pressure of the refrigerant, and the like may be provided. . Further, a temperature detection device, a humidity detection device, and a pressure detection device may be provided in the vicinity of the water heat exchanger 2 and the high-low pressure heat exchanger 3.

<Hot water storage device>
Hereinafter, the configuration of the hot water storage device 70 will be described.
The hot water storage device 70 has a function of storing hot water boiled by the heat pump device 60 and supplying the hot water to the outside (faucet or bathtub). A hot water storage tank 71 that stores hot water heated by the water heat exchanger 2, a water pump 72 that supplies water to the water heat exchanger 2, and a water flow rate control valve 73 that adjusts the flow rate are sequentially connected to the hot water storage device 70. Is provided. The water pump 72 only needs to be able to feed water from the hot water storage tank 71 or the water supply device to the water heat exchanger 2. The water pump 72 and the water flow rate control valve 73 are also controlled by the control device 61 of the heat pump device 60.

<Operation mode>
Next, the hot water storage operation mode and the defrosting operation mode performed by the control device 61 of the heat pump device 60 will be described. The hot water storage operation mode is a mode in which water circulating through the hot water storage device 70 is heated to a predetermined temperature. The defrosting operation mode is a mode for melting frost adhering to the air heat exchanger 5 and includes a defrosting preparation operation and a defrosting main operation.

  In the defrosting preparation operation, the refrigerant flows through the main defrosting circuit 20, the auxiliary defrosting circuit 30, and the heating auxiliary circuit 50, and the evaporation temperature (Tei) of the refrigerant flowing into the air heat exchanger 5 is set to be higher than that in the hot water storage operation mode. This operation is performed mainly for the purpose of raising the temperature to be close to the outside temperature, and is performed for the purpose of shortening the time of the main defrosting operation performed thereafter. For example, when the outside air temperature is −10 ° C., the temperature of the frost is, for example, about −15 ° C., and by bringing the evaporation temperature of the refrigerant flowing into the air heat exchanger 5 close to the outside air temperature, so to speak, the piping of the air heat exchanger 5 The temperature is brought close to the outside air temperature, and the temperature of the frost itself adhering to the pipe is brought close to the outside air temperature.

  In the defrosting main operation, similarly to the defrosting preparation operation, the refrigerant is circulated through the main defrosting circuit 20, the auxiliary defrosting circuit 30, and the heating auxiliary circuit 50, and the refrigerant temperature of the air heat exchanger 5 is maintained at, for example, around 0 ° C. This operation is mainly intended to remove frost adhering to the air heat exchanger 5 so that the amount of heat exchange in the water heat exchanger 2 and the air heat exchanger 5 is not reduced.

  The control device 61 repeatedly executes the hot water storage operation mode and the defrosting operation mode alternately according to the state of the air heat exchanger 5.

  FIG. 3 is a timing chart showing the control timing of each device in each operation mode. (A) shows a hot water storage operation, (b) shows a defrost preparation operation, and (c) shows a defrost main operation. FIG. 3 shows each device (compressor 1, expansion valve 4, main side on / off valve 20a, auxiliary side on / off valve 30a, oil return side on / off valve 50a, water flow control valve 73, water pump 72 and fan 5a in each operation. ) Control. In addition, the control device 61 sets the rotation speed (rps) of the compressor 1, the opening degree (pulse) of the expansion valve 4, the opening / closing of the main side opening / closing valve 20a, the opening / closing of the auxiliary side opening / closing valve 30a, and the oil return side opening / closing valve 50a. The water flow rate (L / min) and the rotation speed (rpm) of the fan 5a are controlled by opening and closing, opening control of the water flow control valve 73, and rotation speed control of the water pump 72, respectively. Hereinafter, each operation will be sequentially described in detail using FIG. 3 and a PH diagram corresponding to each operation (hot water storage operation, defrost preparation operation, and defrost main operation).

(A) Hot Water Storage Operation FIG. 4A is a Mollier diagram (PH diagram) showing the refrigerant state of the main circuit 10 during the hot water storage operation. FIG.4 (b) is the figure which showed the location corresponding to each refrigerant | coolant state (1)-(6) of Fig.4 (a) on a refrigerant circuit diagram. In FIG. 4, the vertical axis represents absolute pressure (P) and the horizontal axis represents enthalpy (H). In FIG. 4, L301 indicates the refrigerant state transition, and L304 indicates the outside air temperature. Note that states (1), (5), and (6) are lower than the outside air temperature L304.

  In FIG. 4, the refrigerant is in a gas-liquid two-phase state in a portion surrounded by a saturated liquid line and a saturated vapor line, and is in a liquefied state on the left side of the saturated liquid line. On the right side, the gasified state is shown. That is, it can be seen that the refrigerant is in the stage of transition from the gas-liquid two-phase state to the gas state in the state (1), and that the state is above the critical pressure in the states (2) to (4). In (5) and state (6), it turns out that it is a gas-liquid two-phase state.

  The main purpose of the hot water storage operation is to boil the water circulating through the hot water storage device 70 to a predetermined temperature. Therefore, as shown in FIG. 3, the control device 61 closes the main side opening / closing valve 20 a, the auxiliary side opening / closing valve 30 a, and the oil return side opening / closing valve 50 a so that the refrigerant circulates only in the main circuit 10. Then, the compressor 1 is driven at a predetermined rotational speed (the maximum rotational speed in the present embodiment), the expansion valve 4 is opened to a predetermined opening degree, the fan 5a is driven at the predetermined rotational speed, and the water flow rate is increased. Thus, the opening control of the water flow control valve 73 and the rotation speed control of the water pump 72 are performed.

  With the above control, in the heat pump device 60, first, a high-temperature and high-pressure refrigerant (state (2)) equal to or higher than the critical pressure discharged from the compressor 1 flows into the water heat exchanger 2. In this water heat exchanger 2, the temperature of the refrigerant (state (2)) decreases while radiating a part of the water to the water circulating in the hot water storage device 70, and the refrigerant becomes a low-temperature / high-pressure refrigerant (state (3)). In other words, this water is boiled by passing the heat stored in the refrigerant to the water circulating in the hot water storage device 70. The refrigerant (state (3)) flowing out from the water heat exchanger 2 flows into the high / low pressure heat exchanger 3. This refrigerant (state (3)) becomes a low-temperature / high-pressure refrigerant (state (4)) in which heat is radiated by the high-low pressure heat exchanger 3 and the temperature is further reduced.

  Thereafter, the refrigerant (state (4)) flowing out from the high / low pressure heat exchanger 3 flows into the expansion valve 4. The refrigerant (state (4)) flowing into the expansion valve 4 is decompressed by the expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant (state (5)). This gas-liquid two-phase refrigerant (state (5)) flows into the air heat exchanger 5 and absorbs heat from the air sent from the fan 5a to evaporate and is a low-temperature / low-pressure gas-liquid two-phase refrigerant (state (6)). It becomes. The gas-liquid two-phase refrigerant (state (6)) flowing out from the air heat exchanger 5 flows into the low pressure pipe 3b of the high and low pressure heat exchanger 3, flows out of the water heat exchanger 2 and passes through the high pressure pipe 3a side. The refrigerant is heated by exchanging heat with the low-temperature and high-pressure refrigerant (state (3)) to be changed from a gas-liquid two-phase refrigerant to a gas refrigerant (that is, refrigerant in the state (1)). The refrigerant (state (1)) is sucked into the compressor 1 so that the main circuit 10 is formed.

  However, in the hot water storage operation mode under a condition where the outside air temperature is low, for example, 0 ° C. or less, frost may adhere to the surface of the air heat exchanger 5 because the surface temperature of the air heat exchanger 5 decreases. If it does so, while the heat exchange efficiency in the air heat exchanger 5 will fall, the refrigerant | coolant temperature in the air heat exchanger 5 will also fall. Further, if the hot water storage operation mode is continued, frost attached to the air heat exchanger 5 grows, and a sufficient amount of heat for efficient heating by the water heat exchanger 2 cannot be absorbed from the outside air. It will be.

  Therefore, when it is determined that the preset defrosting start timing has been reached, the control device 61 starts the defrosting operation mode. Here, the opening degree of the expansion valve 4 when starting the defrosting main operation in the defrosting operation mode is different from that in the hot water storage operation mode, as is apparent from FIG. For this reason, if the hot water storage operation is directly switched to the defrosting main operation and the opening degree of the expansion valve 4 is suddenly changed or the rotation speed of the compressor 1 is changed, the dryness of the refrigerant at the inlet of the compressor 1 is increased. The temperature becomes below the outside air temperature, and a large amount of liquid refrigerant flows into the compressor 1. Therefore, in the present embodiment, the defrost preparation operation is performed before the defrost main operation. Next, the defrost preparation operation will be described.

(B) Defrost preparation operation FIG. 5 is a Mollier diagram (PH diagram) showing refrigerant states of the main circuit 10, the main defrost circuit 20, and the auxiliary defrost circuit 30 during the defrost preparation operation. In FIG. 5, the vertical axis represents absolute pressure (P) and the horizontal axis represents enthalpy (H). In FIG. 5, L302 indicates the state transition of the refrigerant, and L304 indicates the outside air temperature. In addition, states (1) to (6) illustrated on L302 indicate the states of the refrigerant at the respective locations (1) to (6) illustrated in FIG. In addition, states (1), (5), (5 ′), (5 ″), and (6) are lower than the outside air temperature L304.

  In FIG. 5, the refrigerant is in a gas-liquid two-phase state in a portion surrounded by a saturated liquid line and a saturated vapor line, and is in a liquefied state on the left side of the saturated liquid line. On the right side, the gasified state is shown. That is, the refrigerant is found to be in a gas state in the state (1), is found to be in a state equal to or higher than the critical pressure in the states (2) to (4), and is in a liquid state and a state in the state (5 ″). In (5), (5 ') and (6), it turns out that it is a gas-liquid two phase state.

  As described above, the defrost preparation operation is mainly intended to shorten the time of the defrost main operation, that is, to make the evaporation temperature (Tei) faster than the outside air temperature. The operation is started by opening the main-side on-off valve 20a (see P1 in FIG. 3). That is, the hot-side storage operation is switched to the defrost preparation operation by controlling the opening of the main-side on-off valve 20a. Then, as shown in FIG. 3, the oil return side on-off valve 50a is controlled to open simultaneously with the start of the defrost preparation operation. Further, the opening control of the auxiliary opening / closing valve 30a is performed simultaneously with the start of the defrosting preparation operation (timing at which the opening control of the main opening / closing valve 20a) or thereafter. That is, in the defrost preparation operation, the refrigerant flows through all of the main defrost circuit 20, the auxiliary defrost circuit 30, and the heating auxiliary circuit 50.

  In the defrost preparation operation, the opening degree control of the expansion valve 4 is also characterized. However, the opening degree control and control of each device will be described later. Here, first, the main defrosting circuit 20 and the auxiliary defrosting are performed. The refrigerant flow and the change in the refrigerant state caused by flowing the refrigerant through all of the circuit 30 and the heating auxiliary circuit 50 will be described.

  By opening the main-side on-off valve 20a, the high-temperature and high-pressure refrigerant (state (2)) discharged from the compressor 1 flows not only to the main circuit 10 but also to the main defrosting circuit 20 (that is, the first bypass pipe 22). Thus, the defrost preparation operation is started. Note that the refrigerant separated into the main circuit 10 and the main defrosting circuit 20 at the branching portion 21 is merged at the inlet side (merging portion 23) of the high / low pressure heat exchanger 3, and the refrigerant (state ( 3)).

  At this time, the refrigerant (state (2)) flowing into the main defrosting circuit 20 side becomes a refrigerant (state (3 ″)) that maintains a relatively high temperature even though it flows through the main defrosting circuit 20. On the other hand, the refrigerant flowing through the main circuit 10 (state (2)) flows into the water heat exchanger 2 with the refrigerant flow rate decreased by opening the main-side on-off valve 20a. Therefore, the heat exchange amount in the water heat exchanger 2 is also reduced. That is, the amount of heat that can be transferred to the water circulating through the hot water storage device 70 is reduced. Therefore, the temperature of the refrigerant (state (3 ')) flowing out from the water heat exchanger 2 is not relatively lowered.

  The refrigerant flowing through the main circuit 10 (state (3 ′)) and the refrigerant flowing through the main defrosting circuit 20 (state (3 ″)) merge at the inlet side (merging portion 23) of the high / low pressure heat exchanger 3, The refrigerant becomes a relatively high temperature / high pressure refrigerant (state (3)). Although this refrigerant (state (3)) is lower than the temperature of the refrigerant (state (2)) at the branching section 21, as described above, high-low pressure heat exchange is performed while maintaining a relatively high temperature. Will flow into the vessel 3.

  That is, since the refrigerant (state (3)) after the main circuit 10 and the main defrosting circuit 20 merge at the junction 23 has a relatively high temperature, the heat exchange amount of the high-low pressure heat exchanger 3 is high. It will increase. The refrigerant (state (3)) that flows into the high-pressure pipe 3a side of the high-low pressure heat exchanger 3 decreases in temperature while partially radiating heat to the gas-liquid two-phase refrigerant (state (6)) that flows through the low-pressure pipe 3b side. Thus, the refrigerant becomes a low-temperature and high-pressure refrigerant (state (4)). The refrigerant (state (4)) that has flowed out from the high-pressure pipe 3 a side of the high-low pressure heat exchanger 3 flows into the expansion valve 4.

  The refrigerant (state (4)) flowing into the expansion valve 4 is decompressed by the expansion valve 4 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant (state (5 ')). On the other hand, by controlling the opening of the auxiliary side opening / closing valve 30a of the auxiliary defrosting circuit 30, the high-temperature refrigerant discharged from the compressor 1 flows through the lowermost flow path of the air heat exchanger 5, and the air heat exchanger After the lower part of 5 is heated, it becomes a state of low dryness (state (5 ″)) and joins at the merging portion 33 on the air heat exchanger inlet side of the main circuit 10 to become the state (5).

  This gas-liquid two-phase refrigerant (state (5)) flows into the air heat exchanger 5, absorbs heat from the air sent from the fan 5a and evaporates, and is a low-temperature and low-pressure gas-liquid two-phase refrigerant (state (6)). ) In addition, the heat exchange amount in the air heat exchanger 5 is reduced as the heat radiation amount (heat exchange amount) in the water heat exchanger 2 is reduced. Moreover, if the heat exchange amount in the air heat exchanger 5 decreases, the evaporation temperature (Tei) detected by the evaporation temperature detector 7a also rises higher than the evaporation temperature during hot water storage operation.

  The gas-liquid two-phase refrigerant (state (5 ′)) flowing out of the expansion valve 4 and flowing into the air heat exchanger 5 from the main circuit 10 (state (5 ′)) is a liquid refrigerant (state (state ( 5 ″)) and the merging section 33 and then flows into the air heat exchanger 5. For this reason, the gas-liquid two-phase refrigerant (state (6)) flowing out from the air heat exchanger 5 is compared with the case where the liquid refrigerant (state (5 ″) from the auxiliary defrost circuit 30 is not merged at the junction 33. The dryness will decrease.

  However, since the amount of heat exchange in the high / low pressure heat exchanger 3 is increased as described above by opening the main side opening / closing valve 20a of the main defrosting circuit 20, it flows out of the air heat exchanger 5. The gas-liquid two-phase refrigerant (state (6)) flowing into the high / low pressure heat exchanger 3 is sufficiently heated by the high / low pressure heat exchanger 3. The refrigerant that has flowed out of the high / low pressure heat exchanger 3 is stored in the outer or inner oil of the oil separator 1a at the discharge portion of the compressor 1 by opening control of the oil return side on-off valve 50a of the auxiliary heating circuit 50. The collected heat is recovered and further heated and sucked into the compressor 1.

  That is, the gas-liquid two-phase refrigerant in the state (6) passes through the high / low pressure heat exchanger 3 and further joins with the oil from the heating auxiliary circuit 50, so that it is sufficiently heated when sucked into the compressor 1. It becomes a gas refrigerant (state (1)).

  Here, compared with the technique of the conventional patent document 1, it corresponds to the structure which connected the edge part by the side of the refrigerant | coolant exit of the 2nd bypass pipe 32 of this Embodiment to the exit side of the air heat exchanger 5 conventionally. As described above, the refrigerant passing through the second bypass pipe 32 passes through the lowermost stage of the air heat exchanger 5 and thus has a low dryness. Since the refrigerant in such a low dryness state is joined to the outlet side of the air heat exchanger 5, liquid return to the compressor 1 cannot be avoided and an accumulator is necessary.

  On the other hand, by connecting the end of the second bypass pipe 32 on the refrigerant outlet side to the inlet side of the high / low pressure heat exchanger 3 as in the present embodiment, a low dryness state (state (5 '' )) Can be combined with the refrigerant from the main circuit 10 and then flowed into the air heat exchanger 5 to be stored in the air heat exchanger 5. By increasing the amount of heat exchange at, an accumulator can be made unnecessary.

  Next, a specific control example of each device in the defrost preparation operation will be described with reference to FIG.

  In the above description, the opening degree control of the expansion valve 4 and the rotation speed control of the compressor 1 have not been specifically described. However, in order to bring the evaporation temperature close to the outside temperature quickly, the rotation speed of the compressor 1 is set during hot water storage operation. And a method of increasing the opening degree of the expansion valve 4 than in the hot water storage operation. FIG. 3 shows an example in which both are performed, but either one of the methods may be adopted to raise the evaporation temperature. Although the opening degree of the expansion valve 4 is increased, in the present embodiment, as shown in FIG. 3, the opening degree of the expansion valve 4 is once decreased before being increased. The reason for this will be described later. First, the operation when the rotation speed of the compressor 1 is controlled to be lower than that during hot water storage operation and the opening degree of the expansion valve 4 is increased will be described.

  FIG. 6 is an explanatory diagram illustrating an example of control of the rotation speed of the compressor 1 and the opening degree of the expansion valve 4. As shown in FIG. 6, the rotational speed of the compressor 1 and the opening degree of the expansion valve 4 are greatly changed simultaneously with the start of the defrosting operation mode, that is, the rotational speed of the compressor 1 is suddenly decreased, If the value is suddenly increased, the amount of refrigerant flowing into the air heat exchanger 5 will increase rapidly. That is, the dryness of the refrigerant at the inlet of the compressor 1 becomes transiently below the outside air temperature L304, and the amount of liquid returned to the compressor 1 increases.

  Therefore, in the present embodiment, the defrost preparation operation is performed, the rotational speed of the compressor 1 is gradually decreased, and the opening degree of the expansion valve 4 is gradually increased so that the refrigerant flows into the air heat exchanger 5. The evaporation temperature (Tei) can be increased while the amount is gradually increased and the amount of liquid returned to the compressor 1 is kept small. At this time, by driving the fan 5a at the same rotational speed as in the hot water storage operation, the dryness of the refrigerant at the outlet of the air heat exchanger 5 is drastically reduced and liquid return to the compressor 1 occurs. Can be suppressed. Then, after a certain time (the time for which the refrigerant makes one cycle of the cycle, for example, from about 30 seconds to about 1 minute), the rotational speed of the compressor 1 gradually increases so as to become the same as the rotational speed in the hot water storage operation mode. Let The reason for the increase is to maintain the temperature of the high-pressure pipe 3a of the high-low pressure heat exchanger 3 at a high level, thereby increasing the capacity of the high-low pressure heat exchanger 3 and preventing the liquid from returning to the compressor 1. is there.

  Next, the reason why the opening degree of the expansion valve 4 is once lowered at the start of the defrost preparation operation will be described. The air heat exchanger 5 at the start of the defrost preparation operation holds liquid refrigerant that has been kept at a low temperature during the hot water storage operation. Therefore, if the opening degree of the expansion valve 4 is increased simultaneously with the start of the defrost preparation operation, the low-temperature liquid refrigerant in the air heat exchanger 5 may be released at a time and returned to the compressor 1. Therefore, in order to prevent this, at the same time when the defrost preparation operation is started, the opening degree of the expansion valve 4 is once reduced to reduce the refrigerant flowing out from the air heat exchanger 5 to the compressor 1.

  In addition, during the defrost preparation operation, the fan 5a is driven at the same rotational speed as in the hot water storage operation as shown in FIG. 3, so that the dryness of the refrigerant at the outlet of the air heat exchanger 5 is drastically reduced. As a result, liquid return to the compressor 1 can be suppressed. Further, the opening degree control of the water flow rate control valve 73 and the rotation speed control of the water pump 72 are performed to control the flow rate to be smaller than that in the hot water storage operation mode. The water pump 72 may be stopped.

  In order to gradually decrease the rotational speed of the compressor 1 and gradually increase the opening degree of the expansion valve 4, it may be continuous as shown in FIG. 3, or as shown in FIG. You may make it change in steps.

  FIG. 7 is a diagram showing an example in which the rotational speed of the compressor 1 is lowered stepwise and the opening degree of the expansion valve 4 is once reduced and then increased stepwise. As shown in FIG. 7, the opening degree of the expansion valve 4 is increased in steps at predetermined time intervals, or is controlled to increase continuously as shown in the previous figure. As described above, the amount of the refrigerant flowing into the air heat exchanger 5 is prevented from rapidly increasing. If it does so, the dryness of the refrigerant | coolant in the inlet_port | entrance of the compressor 1 will always become more than the external temperature L304, and it can switch to a defrost main operation, without increasing the liquid return amount to the compressor 1. FIG.

  And if this defrost preparation operation is continued, the temperature and evaporation temperature (tei) of the refrigerant | coolant (state (3 ')) in the exit of the water heat exchanger 2 will continue to rise, and the amount of heat in the compressor 1 will increase. The amount of heat exchange in the water heat exchanger 2 is smaller than that. Therefore, the heat of the gas-liquid two-phase refrigerant (state (5)) is radiated to the air side by the air heat exchanger 5, so that the air heat exchanger 5 starts to function as a condenser. When the evaporation temperature (tei) exceeds the outside air temperature, the control device 61 switches to the defrost main operation. Next, the defrost main operation will be described.

(C) Main Defrosting Operation FIG. 8 is a Mollier diagram (PH diagram) showing refrigerant states of the main circuit 10, the main defrosting circuit 20, and the auxiliary defrosting circuit 30 during the defrosting main operation. In FIG. 8, the vertical axis represents absolute pressure (P) and the horizontal axis represents enthalpy (H). In FIG. 8, L303 indicates the refrigerant state transition, and L304 indicates the outside air temperature. In addition, states (1) to (6) illustrated on L303 indicate the states of the refrigerant in the respective locations (1) to (6) illustrated in FIG. In any state, the temperature is higher than the outside air temperature L304.

  In FIG. 8, the refrigerant is in a gas-liquid two-phase state in a portion surrounded by a saturated liquid line and a saturated vapor line, and is in a liquefied state on the left side of the saturated liquid line. On the right side, the gasified state is shown. That is, the refrigerant is found to be in a gas state in the state (1), is found to be in a state equal to or higher than the critical pressure in the states (2) to (4), and is in a liquid state and a state in the state (5 ″). In (5), (5 ′), (5 ″) and (6), it can be seen that the gas-liquid two-phase state.

  The defrosting main operation is a mode started after the defrosting preparation operation, and the control device 61 keeps the main side opening / closing valve 20a, the auxiliary side opening / closing valve 30a, and the oil return side opening / closing valve 50a open. The defrosting main operation is started (see P2 in FIG. 3).

  The control of each device such as the compressor 1 and the expansion valve 4 will be described later. First, the refrigerant flow and the change in the refrigerant state during the defrosting main operation will be described.

  In the defrost main operation, similarly to the defrost preparation operation described above, the high-temperature and high-pressure refrigerant discharged from the compressor 1 (state (2)) is not only the main circuit 10 but also the main defrost circuit 20 and the auxiliary defrost circuit. The defrosting main operation is performed so as to flow to 30 and the heating auxiliary circuit 50. In the defrost main operation, the flow of state change of the refrigerant from state (1) to state (5) is the same as that in the defrost preparation operation.

  Since the low-temperature / low-pressure gas-liquid two-phase refrigerant (state (5)) is after the defrost preparation operation, the refrigerant temperature is equal to or higher than the outside air temperature L304. This gas-liquid two-phase refrigerant (state (5)) flows into the air heat exchanger 5, absorbs heat from the air sent from the fan 5a and evaporates, and is a low-temperature and low-pressure gas-liquid two-phase refrigerant (state (6)). ) In addition, the heat exchange amount in the air heat exchanger 5 is reduced as the heat radiation amount (heat exchange amount) in the water heat exchanger 2 is reduced. If the amount of heat exchange in the air heat exchanger 5 decreases, the evaporation temperature (Tei) detected by the evaporation temperature detector 7a also increases, which is higher than the evaporation temperature during the defrost preparation operation. And if evaporation temperature becomes 0 degreeC or more, the frost adhering to the air heat exchanger 5 can be melt | dissolved.

  Here, in the air heat exchanger 5, the evaporation temperature is higher than that during the defrost preparation operation, and the change from the state (5) to the state (6) during the defrost preparation operation shown in FIG. As is clear by comparing the change from the state (5) to the state (6) during the defrost main operation shown in FIG. 8, the defrost main operation is more dry than the defrost preparation operation. The lowered gas-liquid two-phase refrigerant comes out of the air heat exchanger 5. However, as the evaporation temperature in the air heat exchanger 5 rises, the pressure on the discharge side of the compressor 1 increases, so the amount of heat exchange in the high-low pressure heat exchanger 3 is higher than in the defrost preparation operation. doing. For this reason, the refrigerant flowing out of the high / low pressure heat exchanger 3 is sufficiently heated by the high / low pressure heat exchanger 3. The refrigerant flowing out of the high / low pressure heat exchanger 3 recovers the heat stored in the outer and inner oil of the oil separator 1a at the discharge portion of the compressor 1 by opening control of the oil return side on-off valve 50a. When further heated and sucked into the compressor 1, it is sufficiently heated to become a gas refrigerant (state (1)).

  And the refrigerant | coolant amount which exists in the air heat exchanger 5 increases rather than the time of hot water storage driving | running, an excess refrigerant | coolant is stored in the air heat exchanger 5, and it becomes possible to suppress the refrigerant | coolant pressure rise discharged from the compressor 1 now. Yes. Further, the gas-liquid two-phase refrigerant (state (6)) that has flowed out of the air heat exchanger 5 is heated by the high-temperature and high-pressure refrigerant (state (3)) flowing into the high-low pressure heat exchanger 3 to be gas refrigerant ( State (1)) is drawn into the compressor 1 to form a cycle.

Next, control of each device in the defrost main operation will be described.
The main purpose of the defrosting operation is to remove the frost adhering to the air heat exchanger 5 as described above and not to reduce the heat exchange amount in the water heat exchanger 2 and the air heat exchanger 5. Yes. Therefore, the control device 61 keeps the rotation speed of the compressor 1 constant at the maximum rotation speed and gradually decreases the opening degree of the expansion valve 4, thereby shortening the defrost main operation time and efficiently performing the defrost main operation. Can be executed.

  Moreover, the defrosting efficiency is improved by lowering the fan 5a from the rotational speed at the time of stopping or defrosting preparation operation, thereby further increasing the evaporation temperature (Tei). In addition, the water flow rate of the hot water storage device 70 is controlled so that the water pump 72 is stopped or the water flow rate control valve 73 is controlled to make the flow rate smaller than in the hot water storage operation, as in the defrost preparation operation. Defrosting efficiency can be improved by controlling each device as described above.

  In addition, although the opening degree of the expansion valve 4 is gradually reduced after entering the defrosting main operation, this is due to the following reason. If the opening degree of the expansion valve 4 remains the same as that in the defrost preparation mode, the discharge side pressure of the compressor 1 decreases, the suction side pressure of the compressor 1 increases, and the input of the compressor 1 is Decrease, defrosting ability decreases. Therefore, in order to prevent this, the opening degree of the expansion valve 4 is gradually reduced.

  Here, since the rotation speed of the compressor 1 reaches the same maximum rotation speed as that in the hot water storage operation mode at the start of the defrosting main operation, the rotation speed of the compressor 1 is kept constant at the maximum rotation speed. However, when the rotation speed of the compressor 1 does not reach the maximum rotation speed at the start of the defrost main operation, the rotation speed of the compressor 1 is gradually increased from the start of the defrost main operation, or The rotation speed may be the same as that in the hot water storage operation mode.

FIG. 9 is a flowchart showing the flow of the switching process of each operation in the heat pump water heater 100 of FIG. Hereinafter, switching of each operation mode will be described.
Usually, the heat pump water heater 100 is performing the hot water storage operation mode (S1). If frost adheres to the air heat exchanger 5 during the hot water storage operation mode, the evaporation temperature (Tei) is lowered. That is, the frosting state on the air heat exchanger 5 can be determined by the evaporation temperature (Tei). When the heat pump water heater 100 starts the hot water storage operation mode, the control device 61 compares the evaporation temperature (Tei) detected by the evaporation temperature detection device 7a with a predetermined value (T1) set in advance (S2).

  The controller 61 continues the hot water storage operation mode until the evaporation temperature (Tei) becomes equal to or lower than a predetermined value (T1). The predetermined value (T1) is a preset temperature at which it is assumed that frost will adhere to the air heat exchanger 5 and the heat exchange amount of the air heat exchanger 5 will decrease.

  When determining that the evaporation temperature (Tei) has become equal to or lower than the predetermined value (T1), the control device 61 determines the defrosting operation start timing, switches from the hot water storage operation mode to the defrosting operation mode, and starts the defrosting preparation operation first. (S3). Since the evaporation temperature (Tei) gradually increases as described above by starting the defrost preparation operation, the defrost preparation operation is performed while the increased evaporation temperature (Tei) is within a predetermined value (Tx). If it continues (S4) and exceeds predetermined value (Tx), the control apparatus 61 will switch to defrost main operation (S5). Although the predetermined value (Tx) has been described as the outside air temperature in the above, it may be a temperature equal to or higher than the outside air temperature, and may be 0 ° C. that is the melting point of ice.

  And if a defrost main operation is performed, since the frost adhering to the air heat exchanger 5 will melt | dissolve, evaporation temperature (Tei) will rise. Therefore, the control device 61 compares the evaporation temperature (Tei) with a predetermined value (T2) set in advance (S6). The controller 61 continues the defrost main operation until the evaporation temperature (Tei) becomes equal to or higher than a predetermined value (T2). That is, the control device 61 determines that the frost attached to the air heat exchanger 5 has not melted while the evaporation temperature (Tei) is lower than the predetermined value (T2), and continues the defrosting main operation. When the controller 61 determines that the evaporation temperature (Tei) has reached the predetermined value (T2) or more, it determines that it is time to return to the hot water storage operation mode when the frost melts, and switches from the defrost main operation to the hot water storage operation again. (S1). The predetermined value (T2) is a preset temperature at which it is assumed that the frost attached to the air heat exchanger 5 will melt and the heat exchange amount of the air heat exchanger 5 will not decrease.

  As described above, the heat pump water heater 100 has different cycle states between the hot water storage operation and the defrost main operation by opening the main side opening / closing valve 20a, the auxiliary side opening / closing valve 30a, and the oil return side opening / closing valve 50a. In addition, the cycle state can be efficiently changed from the hot water storage operation to the defrost main operation by executing the defrost preparation operation that connects the hot water storage operation and the defrost main operation.

  As described above, according to the heat pump device 60 of the present embodiment, a branch is made between the compressor 1 and the water heat exchanger 2 and below the lowermost refrigerant pipe of the air heat exchanger 5. Since the auxiliary defrosting circuit 30 that passes through and merges with the inlet side of the air heat exchanger 5 is provided, the refrigerant flowing out of the auxiliary defrosting circuit 30 as liquid refrigerant by heat exchange with the frost is converted into the air heat exchanger. 5 and can be stored in the air heat exchanger 5. In addition, since the amount of heat exchange in the high-low pressure heat exchanger 3 can be increased by the main defrosting circuit 20, the liquid return to the compressor 1 without generating surplus refrigerant, that is, without using a refrigerant container. The amount can be suppressed. Moreover, even if the air heat exchanger 5 is configured to have a height in the vertical direction by heating the lowermost part of the air heat exchanger 5 by the auxiliary defrosting circuit 30, the air heat exchanger 5 The frost accumulated at the bottom can be melted, and defective defrost such as residual ice can be prevented.

  Moreover, by performing defrost main operation after passing through defrost preparation operation, a liquid return can be suppressed and the efficient defrost main operation is implement | achieved. Further, in the defrost preparation operation and the defrost main operation, the defrosting can be further efficiently performed by controlling the rotation speed of the compressor 1, the opening degree of the expansion valve 4, and the rotation speed of the fan 5a, thereby shortening the defrosting time. Makes it possible to plan.

  In the above description, regarding the opening / closing control of the auxiliary side opening / closing valve 30a, an example in which complicated control is not performed and opening control is performed at the same time as the start of the defrost preparation operation is shown. The opening control may be performed after detecting that the amount of heat exchange in the heat exchanger 3 has increased (for example, by detecting the temperature at the inlet of the high / low pressure heat exchanger 3 and a predetermined value (Ty) or more). This is because even if the liquid refrigerant stays in the second bypass pipe 32 of the auxiliary defrost circuit 30 due to the hot water storage operation, the staying liquid refrigerant controls the opening of the auxiliary side opening / closing valve 30a. This is for preventing the air heat exchanger 5 and the high / low pressure heat exchanger 3 from flowing into the compressor 1 with a low dryness without being evaporated. Therefore, this control is more effective for suppressing liquid return.

  Note that the values of the predetermined value (T1), the predetermined value (Tx), the predetermined value (Ty), and the predetermined value (T2) shown in the present embodiment are not particularly limited. It is good to set based on conditions, such as a use of a heat pump device 60, an installation place, and performance. Further, it is preferable that these predetermined values can be changed.

  Moreover, in this Embodiment, although the heating auxiliary circuit 50 is provided, only the main defrosting circuit 20 and the auxiliary defrosting circuit 30 can fully heat the refrigerant discharged from the high-low pressure heat exchanger 3 and gasify it. The auxiliary heating circuit 50 can be omitted. However, it is more preferable to provide the heating auxiliary circuit 50.

Further, when CO ₂ is used as the refrigerant, CO ₂ has a small gas-liquid density difference, so that a large amount of refrigerant can be stored on the air heat exchanger 5 side. Moreover, since the temperature of the refrigerant discharged from the compressor 1 becomes high, CO ₂ also has an effect that the gas-liquid two-phase refrigerant flowing out from the air heat exchanger 5 is easily heated and gasified by the high-low pressure heat exchanger 3. . Furthermore, the evaporating temperature detection device 7a may be provided at an intermediate position of the refrigerant pipe that circulates through the air heat exchanger 5. Note that a low pressure detection device may be provided in the middle of the refrigerant pipe (low pressure) from the outlet of the expansion valve 4 to the inlet of the compressor 1, and the calculated saturation temperature may be used as the evaporation temperature (Tei).

Further, when CO ₂ is used as the refrigerant, the pressure difference between the front and rear of the second bypass pipe 32 is large, so that the pipe size of the second bypass pipe 32 portion in the air heat exchanger 5 can be reduced.

  Further, in the present embodiment, as a specific configuration of the main defrosting circuit 20 that guides the refrigerant discharged from the compressor 1 to the inlet of the high-low pressure heat exchanger 3 in a state where the temperature is higher than that during hot water storage operation, Although the example comprised with the 1st bypass piping 22 which has the side on-off valve 20a was shown, it is not restricted to this structure, You may make it the main circuit 10 itself serve as the main defrost circuit 20 as well. In this case, the opening degree of the water flow control valve 73 and the rotation speed of the water pump 72 may be adjusted. Specifically, the amount of heat exchange in the water heat exchanger 2 is reduced by stopping or reducing the water flow rate with the start of the defrost preparation operation, and the outlet refrigerant temperature of the water heat exchanger 2 is increased. That is, the inlet refrigerant temperature of the high / low pressure heat exchanger 3 can be increased.

  Also with this configuration, substantially the same effect that the amount of liquid return to the compressor 1 can be reduced is obtained. However, in order to prevent boiling of water in the water heat exchanger 2, when the temperature at the outlet of the water heat exchanger 2 is equal to or higher than a predetermined value (for example, 80 ° C.), the water flow rate is increased once and the water heat exchanger 2 After reducing the temperature of the water inside, it is necessary to reduce the water flow rate.

In the above embodiment, the case using the CO ₂ refrigerant as refrigerant shown in the example, not limited thereto. For example, a mixed refrigerant obtained by mixing CO ₂ with hydrocarbons having a high azeotropic property with CO ₂ , such as propane, cyclopropane, isobutane, butane and the like may be used. If such a mixed refrigerant is used, the critical pressure can be further reduced as compared with the case of a CO ₂ simple substance refrigerant.

  Moreover, in the said embodiment, although the case where the heat pump apparatus 60 was applied to the heat pump water heater was demonstrated to the example, it is not limited to this, For example, apparatus, such as a car air-conditioner, an air conditioning apparatus, a refrigerator, a refrigerator, etc. May be applied.

  1 Compressor, 1a Oil separator, 2 Water heat exchanger, 3 High / low pressure heat exchanger, 3a High pressure piping, 3b Low pressure piping, 4 Expansion valve, 5 Air heat exchanger, 5a Fan, 7a Evaporation temperature detector, 7b Outside air temperature detection device, 10 main circuit, 11 sequential refrigerant piping, 20 main defrost circuit, 20a main side opening / closing valve, 21 branching section, 22 first bypass pipe, 23 merge section, 30 auxiliary defrosting circuit, 30a auxiliary side opening / closing Valve, 31 branch section, 32 second bypass pipe, 33 merge section, 40 oil return bypass circuit, 50 heating auxiliary circuit, 50a oil return side on-off valve, 51 merge section, 52 third bypass pipe, 60 heat pump device, 61 control Apparatus, 70 hot water storage apparatus, 71 hot water storage tank, 72 water pump, 73 water flow control valve, 100 heat pump water heater.

Claims (9)

A compressor, a radiator, a decompressor, and a heat absorber are sequentially connected by a refrigerant pipe, and heat is exchanged between the high-pressure refrigerant on the inlet side of the decompressor and the low-pressure refrigerant on the outlet side of the heat absorber. A main circuit with an exchanger,
A main defrosting circuit for guiding the high-temperature refrigerant discharged from the compressor to a high-low pressure heat exchanger at a temperature higher than that during normal operation by reducing heat dissipation in the radiator;
Branching from between the compressor and the radiator of the main circuit, forming an independent flow path different from the main circuit among the auxiliary side on-off valve and the refrigerant piping of the plurality of stages of the heat absorber. A heat pump device comprising: an auxiliary defrosting circuit that merges with an inlet side of the heat absorber via a lowermost refrigerant pipe.   2. The defrosting operation in which the heat absorber is defrosted, a refrigerant flows through the main defrosting circuit, and the auxiliary side opening / closing valve of the auxiliary defrosting circuit is opened during the defrosting operation. The heat pump apparatus as described.   The heat pump apparatus according to claim 2, wherein the opening degree of the decompression device is once reduced immediately after the start of the defrosting operation.   A temperature detection device that detects the temperature of the high-low pressure heat exchanger inlet, and during the defrosting operation that performs defrosting of the heat absorber, when the detected temperature of the temperature detection device is equal to or higher than a predetermined value, The heat pump device according to any one of claims 1 to 3, wherein the auxiliary side opening / closing valve of the auxiliary defrosting circuit is opened. An oil separator for separating oil in the refrigerant discharged from the compressor;
A heating auxiliary circuit that is provided with an oil return side on-off valve, returns oil separated by the oil separator to the suction side of the compressor, and heats the refrigerant from the heat absorber toward the compressor by the oil. And
5. The heat pump device according to claim 1, wherein the oil return side opening / closing valve of the heating auxiliary circuit is opened during the defrosting operation. The defrosting operation is
A defrost preparation operation for increasing the evaporation temperature of the refrigerant flowing into the heat absorber;
A defrost main operation that is performed after the defrost preparation operation and melts frost adhering to the heat absorber. In the defrost main operation, the number of rotations of the compressor is increased compared to that during the defrost preparation operation. The heat pump device according to any one of claims 1 to 5, wherein the heat pump device is used. The defrosting operation is
A defrost preparation operation for increasing the evaporation temperature of the refrigerant flowing into the heat absorber;
A defrost main operation that is performed after the defrost preparation operation and melts frost adhering to the heat absorber, and the rotation speed of the compressor is maintained at a maximum rotation speed in the defrost main operation. The heat pump device according to any one of claims 1 to 5.   The heat pump device according to any one of claims 1 to 7, wherein carbon dioxide is used as a refrigerant. The heat pump device according to any one of claims 1 to 8,
A hot water storage device comprising a water pump for feeding water to the radiator and a hot water storage tank for storing water heated by the radiator;
The said control apparatus controls the drive of the said water pump, and performs hot water storage operation, defrost preparation operation, and defrost operation, The heat pump water heater characterized by the above-mentioned.