JP7097762B2 - Heat pump, heat pump control method - Google Patents

Description

The present invention relates to a heat pump provided with a refrigerant circuit and a control method for the heat pump.

Conventionally, there has been known a refrigeration cycle, that is, a heat pump, which is provided with a refrigerant circuit in which a refrigerant repeatedly compresses and expands to circulate. In such a heat pump, for example, as described in Patent Document 1, a low-stage compressor that compresses the refrigerant and a high-stage compressor that further compresses the refrigerant discharged from the low-stage compressor are used. The refrigerant may be compressed in two stages.

Such a heat pump is provided with an evaporator that evaporates the refrigerant on the upstream side of the low-stage compressor. The evaporator is a heat exchanger that exchanges heat between, for example, a refrigerant and a heat medium such as water or air.

Japanese Unexamined Patent Publication No. 2016-90102

Here, in the heat pump of Patent Document 1, the refrigerant from the evaporator is introduced into the low-stage compressor and then introduced into the high-stage compressor.
However, the amount of heat exchange in the evaporator is not always constant and may fluctuate due to environmental factors and the like. Therefore, the temperature of the refrigerant introduced from the heat exchanger into the low-stage compressor is not constant, and the refrigerant introduced into the low-stage compressor is not in the optimum state for compression in the low-stage compressor. Therefore, it may not be possible to operate the heat pump efficiently as a whole.

Therefore, the present invention provides a heat pump capable of efficiently operating by introducing a refrigerant in an optimum state for compression into a low-stage compressor and a high-stage compressor, and a heat pump control method.

The heat pump according to the first aspect of the present invention is from a low-stage compressor that compresses the refrigerant, a high-stage compressor that further compresses the refrigerant from the low-stage compressor, and the high-stage compressor. From the condenser that condenses the refrigerant, the expansion section that decompresses the refrigerant from the condenser, the evaporator that is connected to the expansion section and evaporates the refrigerant from the expansion section, and the high-stage compressor. The first path for introducing the refrigerant of the above into the condenser and introducing the refrigerant from the evaporator into the low-stage compressor, and introducing the refrigerant from the high-stage compressor into the evaporator. In addition, a four-way switching valve that can select a second path for introducing the refrigerant from the condenser to the low-stage compressor and a low-stage refrigerant from the evaporator without passing through the four-way switching valve. It is possible to selectively introduce the refrigerant from the evaporator to the high-stage compressor without passing through the four-way switching valve and the low-stage compressor. It is equipped with a bypass flow path, which can be performed in .

In the evaporator, the amount of heat exchange fluctuates and the temperature of the refrigerant changes, so that the state of the refrigerant toward the low-stage compressor and the high-stage compressor changes in these low-stage compressors and high-stage compressors. It may not be optimal for compression. Here, in this embodiment, the provision of the bypass flow path not only introduces the refrigerant from the evaporator to the low-stage compressor, but also bypasses the low-stage compressor and directly feeds the refrigerant to the high-stage compressor. Can be introduced. Therefore, the path of the refrigerant can be switched to the compressor capable of optimum compression according to the state of the refrigerant flowing out from the evaporator.
Further, the refrigerant from the evaporator can be introduced into the low-stage compressor or directly into the high-stage compressor without going through the four-way switching valve. Therefore, even if the heat pump has a four-way switching valve and can change the flow path of the refrigerant, the bypass flow path can be easily introduced into the compressor capable of optimal compression of the refrigerant from the evaporator. It is possible to add a new one.

Further, the heat pump may further include an on-off valve provided in the bypass flow path to open and close the bypass flow path, and a control unit for operating the on-off valve and the four-way switching valve.

By providing the control unit, the path of the refrigerant can be automatically switched so as to introduce the refrigerant into the compressor capable of optimum compression according to the state of the refrigerant flowing out from the evaporator.

Further, in the above heat pump, the evaporator is provided in parallel with the first heat exchanger for heat exchange between the refrigerant and the first heat medium, and the refrigerant and the second heat medium. It has a second heat exchanger that exchanges heat between the two, and the bypass flow path is a first heat exchange low-stage bypass portion that connects the first heat exchanger and the low-stage side compressor. , The first heat exchange high-stage bypass portion that connects the first heat exchanger and the high-stage side compressor without going through the low-stage side compressor, and the second heat exchanger and the low-stage side. Second heat exchange height that connects the second heat exchanger and the high-stage side compressor without going through the second heat exchange low-stage bypass section that connects the side compressor and the low-stage side compressor. The on-off valve has a stage bypass portion, and the on-off valve includes a first valve provided in the first heat exchange low stage bypass portion, a second valve provided in the first heat exchange high stage bypass portion, and the above. It may have a third valve provided in the second heat exchange low-stage bypass portion and a fourth valve provided in the second heat exchange high-stage bypass portion.

Since the bypass flow path has each bypass portion connecting between the first heat exchanger and the second heat exchanger and each compressor, from the first heat exchanger and the second heat exchanger, The refrigerant can be directly introduced into any compressor. Therefore, more optimum compression of the refrigerant becomes possible according to various states of the refrigerant.

Further, the heat pump is provided with a flow path connecting the second heat exchanger and the four-way switching valve, and the second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion are described. It is provided so as to branch from the flow path, and is located on the four-way switching valve side in the flow path from the branch positions of the second heat exchange low-stage bypass section and the second heat exchange high-stage bypass section from the flow path. It may further be provided with a check valve that is provided and allows only the flow of refrigerant from the four-way switching valve to the second heat exchanger.

With such a check valve, when introducing the refrigerant from the second heat exchanger to each compressor via the bypass flow path without passing through the four-way switching valve, all the refrigerant from the second heat exchanger is introduced. Can flow into the bypass flow path. Therefore, the bypass flow path can be fully functioned.

Further, in the above heat pump, the control unit causes the four-way switching valve to select the second path, and operates the first valve, the second valve, the third valve, and the fourth valve. By closing the bypass flow path, the refrigerant from the high-stage compressor may be introduced into the second heat exchanger via the check valve.

In such a heat pump, by introducing the refrigerant from the high-stage compressor into the second heat exchanger, the defrost operation for removing the frost adhering to the second heat exchanger becomes possible. Further, in this defrost operation, after the refrigerant is absorbed by the condenser to evaporate the refrigerant, the refrigerant is compressed by the low-stage compressor and the high-stage compressor, and then the high-temperature and high-pressure refrigerant is exchanged for the second heat. Can be introduced into the vessel. Therefore, the second heat exchanger can effectively defrost in a short time. As a result, the second heat exchanger can be used in a wide operating range.

Further, in the above heat pump, a valve device is further provided between the condenser and the expansion portion, and the control unit stops the flow of the refrigerant from the condenser to the expansion portion by operating the valve device. The four-way switching valve is made to select the second path, and the first valve is operated to open the first heat exchange low-stage bypass portion, and the second valve, the third valve, and the third valve are opened. The fourth valve may be operated to close the first heat exchange high-stage bypass portion, the second heat exchange low-stage bypass portion, and the second heat exchange high-stage bypass portion.

In such a heat pump, by introducing the refrigerant from the high-stage compressor into the second heat exchanger, the defrost operation for removing the frost adhering to the second heat exchanger becomes possible. Further, in this defrost operation, the first heat exchange low-stage bypass portion is opened by the first valve, so that the refrigerant absorbs heat in the first heat exchanger to evaporate the refrigerant, and then the low-stage compressor and the high stage side compressor are used. The refrigerant can be compressed by the stage compressor, and then the high temperature and high pressure refrigerant can be introduced into the second heat exchanger. Therefore, in the second heat exchanger, defrosting can be effectively performed in a short time. As a result, the second heat exchanger can be used in a wide operating range.

Further, in the above heat pump, the expansion portion is parallel to the first expansion valve provided at the inlet of the first heat exchanger between the condenser and the first heat exchanger and the first expansion valve. It has a second expansion valve provided at the inlet of the second heat exchanger between the condenser and the second heat exchanger, the second heat exchanger and the second. A hot gas circuit provided so as to be able to communicate between the expansion valve and the inlet of the lower stage side compressor, a fifth valve provided in the hot gas circuit, and the hot gas circuit provided in the hot gas circuit. Further provided with a check valve that allows only the flow of refrigerant from the inlet of the second heat exchanger to the inlet of the lower stage compressor, the control unit operates the second expansion valve to condense the condensate. By stopping the flow of the refrigerant from the device to the second expansion valve and operating the fifth valve to open the hot gas circuit, the second heat exchanger can be opened via the check valve. The refrigerant may be introduced into the lower stage side compressor.

With such a configuration, so-called hot gas operation can be performed by the control unit. By performing the hot gas operation, the refrigerant can circulate between the second heat exchanger and the low-stage compressor and the high-stage compressor without passing through the condenser.

Further, in the above heat pump, the control unit causes the four-way switching valve to select the first path, and the temperature of the refrigerant flowing out of the first heat exchanger is higher than the temperature of the refrigerant flowing out of the second heat exchanger. If it is also small, the first valve opens the first heat exchange low-stage bypass portion, the second valve closes the first heat exchange high-stage bypass portion, and the third valve closes the second. The heat exchange low-stage bypass portion is closed, the second heat exchange high-stage bypass portion is opened by the fourth valve, and the temperature of the refrigerant flowing out of the first heat exchanger is measured from the second heat exchanger. When the temperature is higher than the temperature of the outflowing refrigerant, the first valve closes the first heat exchange low-stage bypass portion, and the second valve opens the first heat exchange high-stage bypass portion. The second heat exchange low-stage bypass portion may be opened by the three valves, and the second heat exchange high-stage bypass portion may be closed by the fourth valve.

According to such a configuration, when the temperature of the refrigerant flowing out from the first heat exchanger is smaller than the temperature of the refrigerant flowing out from the second heat exchanger, the refrigerant from the first heat exchanger is placed on the lower stage side. It can be introduced into the compressor, and the refrigerant from the second heat exchanger can be directly introduced into the high-stage compressor. Further, when the temperature of the refrigerant flowing out from the first heat exchanger is higher than the temperature of the refrigerant flowing out from the second heat exchanger, the refrigerant from the first heat exchanger is directly introduced into the high-stage compressor. And the refrigerant from the second heat exchanger can be introduced into the lower stage compressor. That is, each of the refrigerants of the refrigerant from the first heat exchanger and the refrigerant from the second heat exchanger can be introduced into the compressor suitable for compression among the low-stage side compressor and the high-stage side compressor.

Further, in the above heat pump, the control unit causes the four-way switching valve to select the first path, the temperature of the refrigerant flowing out of the condenser, the temperature of the refrigerant flowing out of the first heat exchanger, and the above. When the temperature of the refrigerant flowing out of the second heat exchanger is the same, the first valve closes the first heat exchange low-stage bypass portion, and the second valve closes the first heat exchange height. The stage bypass portion may be opened, the second heat exchange low stage bypass portion may be closed by the third valve, and the second heat exchange high stage bypass portion may be opened by the fourth valve.

According to such a configuration, when the temperature of the refrigerant flowing out of the condenser, the temperature of the refrigerant flowing out of the first heat exchanger, and the temperature of the refrigerant flowing out of the second heat exchanger are equal to each other. Can directly introduce the refrigerant from the first heat exchanger into the high-stage side compressor, and can directly introduce the refrigerant from the second heat exchanger into the high-stage side compressor. That is, each of the refrigerants of the refrigerant from the first heat exchanger and the refrigerant from the second heat exchanger can be introduced into the compressor suitable for compression among the low-stage side compressor and the high-stage side compressor.

Further, in the above heat pump, the control unit causes the four-way switching valve to select the first path, and the temperature of the refrigerant flowing out from the first heat exchanger and the temperature of the refrigerant flowing out from the second heat exchanger. , And the temperature between the temperature of the refrigerant flowing out of the first heat exchanger and the temperature of the refrigerant flowing out of the second heat exchanger and the temperature of the refrigerant flowing out of the condenser. If there is a difference, the first valve opens the first heat exchange low-stage bypass portion, the second valve closes the first heat exchange high-stage bypass portion, and the third valve closes the first heat exchange high-stage bypass portion. The second heat exchange low-stage bypass portion may be opened and the second heat exchange high-stage bypass portion may be closed by the fourth valve.

According to such a configuration, the temperature of the refrigerant flowing out from the first heat exchanger and the temperature of the refrigerant flowing out from the second heat exchanger are equal to each other, and from the first heat exchanger. If there is a temperature difference between the temperature of the outflowing refrigerant and the temperature of the refrigerant flowing out of the second heat exchanger and the temperature of the refrigerant flowing out of the condenser, the refrigerant from the first heat exchanger Can be introduced into the low-stage side compressor, and the refrigerant from the second heat exchanger can be introduced into the low-stage side compressor. That is, each of the refrigerants of the refrigerant from the first heat exchanger and the refrigerant from the second heat exchanger can be introduced into the compressor suitable for compression among the low-stage side compressor and the high-stage side compressor.

In the heat pump control method according to the second aspect of the present invention, the four-way switching valve is made to select the first path, and the temperature of the refrigerant flowing out of the first heat exchanger flows out from the second heat exchanger. When the temperature is lower than the temperature of the refrigerant, the first valve opens the first heat exchange low-stage bypass portion, the second valve closes the first heat exchange high-stage bypass portion, and the third valve. The second heat exchange low-stage bypass portion is closed by the fourth valve, and the second heat exchange high-stage bypass portion is opened by the fourth valve, and the temperature of the refrigerant flowing out of the first heat exchanger is the second. When the temperature is higher than the temperature of the refrigerant flowing out of the heat exchanger, the first valve closes the first heat exchange low-stage bypass portion, and the second valve opens the first heat exchange high-stage bypass portion. Then, the second heat exchange low-stage bypass portion is opened by the third valve, and the second heat exchange high-stage bypass portion is closed by the fourth valve.

Further, in the heat pump control method according to the third aspect of the present invention, the four-way switching valve is made to select the first path, the temperature of the refrigerant flowing out of the condenser, and the temperature of the refrigerant flowing out of the first heat exchanger. When the temperature of the refrigerant and the temperature of the refrigerant flowing out of the second heat exchanger are equal, the first valve closes the first heat exchange low-stage bypass portion, and the second valve closes the first heat exchange low-stage bypass portion. The first heat exchange high-stage bypass portion is opened, the second heat exchange low-stage bypass portion is closed by the third valve, and the second heat exchange high-stage bypass portion is opened by the fourth valve. ..

Further, in the heat pump control method according to the fourth aspect of the present invention, the four-way switching valve is made to select the first path, the temperature of the refrigerant flowing out from the first heat exchanger, and the second heat exchanger. The temperature of the refrigerant flowing out of the heat exchanger is the same as the temperature of the refrigerant flowing out of the first heat exchanger, the temperature of the refrigerant flowing out of the second heat exchanger, and the temperature of the refrigerant flowing out of the condenser. When there is a temperature difference between the temperature and the temperature, the first valve opens the first heat exchange low-stage bypass portion, and the second valve closes the first heat exchange high-stage bypass portion. The second heat exchange low-stage bypass portion is opened by the third valve, and the second heat exchange high-stage bypass portion is closed by the fourth valve.

According to the above heat pump and the heat pump control method, the refrigerant in the optimum state for compression can be introduced into the low-stage compressor and the high-stage compressor, and efficient operation becomes possible.

It is the whole block diagram of the heat pump of embodiment of this invention, and shows the operation pattern 1. In addition, the place where the refrigerant flows is indicated by a thick line. It is the whole block diagram of the heat pump of embodiment of this invention, and shows the operation pattern 2. In addition, the place where the refrigerant flows is indicated by a thick line. It is the whole block diagram of the heat pump of embodiment of this invention, and shows the operation pattern 3. In addition, the place where the refrigerant flows is indicated by a thick line. It is the whole block diagram of the heat pump of embodiment of this invention, and shows the operation pattern 4. In addition, the place where the refrigerant flows is indicated by a thick line. It is the whole block diagram of the heat pump of embodiment of this invention, and shows the operation pattern 5. In addition, the place where the refrigerant flows is indicated by a thick line. It is the whole block diagram of the heat pump of embodiment of this invention, and shows the defrost operation pattern 1. In addition, the place where the refrigerant flows is indicated by a thick line. It is the whole block diagram of the heat pump of embodiment of this invention, and shows the defrost operation pattern 2. In addition, the place where the refrigerant flows is indicated by a thick line. It is an overall block diagram of the heat pump of embodiment of this invention, and shows a hot gas operation pattern. In addition, the place where the refrigerant flows is indicated by a thick line.

Hereinafter, the heat pump 1 according to the embodiment of the present invention will be described.
As shown in FIG. 1, the heat pump 1 according to the present embodiment includes a refrigerant circuit 2 that operates in a two-stage compression cycle. The refrigerant circuit 2 has a low-stage compressor 3, a high-stage compressor 4, a condenser 5, an expansion unit 6, and an evaporator 7, and these components are connected in this order by a pipe 10 (flow path). Has been done. Then, a refrigerant such as carbon dioxide circulates in the refrigerant circuit 2. Here, the refrigerant is not particularly limited to carbon dioxide.

Further, the refrigerant circuit 2 has a four-way switching valve 11 provided between the high-stage compressor 4 and the condenser 5. Further, the refrigerant circuit 2 introduces the refrigerant from the evaporator 7 into the low-stage compressor 3 without passing through the four-way switching valve 11 or into the high-stage compressor 4 without passing through the low-stage compressor 3. It has a bypass flow path 12 that enables it. Further, the refrigerant circuit 2 has an on-off valve 13 provided in the bypass flow path 12 for opening and closing the bypass flow path 12, and a control unit 14 for operating the on-off valve 13 and the four-way switching valve 11.

The low-stage compressor 3 sucks in the refrigerant and compresses the refrigerant. In the present embodiment, the low-stage compressor 3 includes a low-stage accumulator 3a that separates the gas and liquid of the refrigerant, a low-stage compressor main body 3b that compresses the gas phase of the refrigerant from the low-stage accumulator 3a, and low-stage compression. It has a low-stage oil separator 3c that removes the lubricating oil in the refrigerant discharged from the machine body 3b.

The high-stage compressor 4 is connected in series with the low-stage compressor 3 and further compresses the refrigerant discharged from the low-stage compressor 3 at a higher pressure. More specifically, in the present embodiment, the high-stage compressor main body 4b that further compresses the refrigerant that has passed through the low-stage oil separator 3c and the high-stage compressor that removes the lubricating oil in the refrigerant discharged from the high-stage compressor main body 4b. It has an oil separator 4c.
The high-stage compressor main body 4b is connected to the low-stage oil separator 3c by an interstage pipe 10a. The high-stage compressor main body 4b further has a high-stage accumulator 4a that is connected to the accumulator pipe 10c that joins in the middle of the interstage pipe 10a and separates the gas and liquid of the refrigerant flowing from the upstream. The high-stage compressor main body 4b is adapted to compress the gas phase of the refrigerant from the high-stage accumulator 4a in addition to the refrigerant from the low-stage oil separator 3c.

The condenser 5 exchanges heat between the high-temperature and high-pressure refrigerant discharged from the high-stage compressor main body 4b of the high-stage compressor 4 and a heat medium such as air or water to cool and condense the refrigerant. .. The condenser 5 is an indoor heat exchanger installed indoors.

The expansion unit 6 adiabatically expands the refrigerant from the condenser 5 and reduces the pressure of the refrigerant. The expansion unit 6 has a plurality of expansion valves 6a, 6b, 6c (three in the present embodiment), and corresponds to the three heat exchangers of the evaporator 7 described later, and is on the upstream side (inlet side) of the evaporator 7. ). A valve device 15 is provided in the connection pipe 10b between the expansion valve 6 and the condenser 5. The valve device 15 opens and closes the flow path of the connecting pipe 10b. A capillary tube or the like may be used instead of the expansion valve 6.

In the present embodiment, the evaporator 7 has a water heat exchanger (first heat exchanger) 31 and an air heat exchanger (second heat exchanger) 32 provided in parallel with the water heat exchanger 31. ing. The evaporator 7 is an outdoor heat exchanger installed outdoors.

The water heat exchanger 31 introduces a refrigerant that has flowed out of the condenser 5 and has passed through the expansion valve (first expansion valve) 6c, and causes heat exchange between the refrigerant and water (first heat medium).

The air heat exchanger 32 introduces the refrigerant that has flowed out of the condenser 5 and has passed through the expansion valves (second expansion valves) 6a and 6b, and exchanges heat between the refrigerant and the air (second heat medium). Let me. Further, in the present embodiment, the air heat exchanger 32 has a first air heat exchange unit 32a and a second air heat exchange unit 32b provided in parallel with each other.

The four-way switching valve 11 is a valve having four ports A, B, C, and D. The port D is connected to the high-stage oil separator 4c by a discharge pipe 10d. Further, the port A and the condenser 5 are connected by a condenser connecting pipe 10e. The port B is connected to the low-stage accumulator 3a by the introduction pipe 10f. The port C is connected to the first air heat exchange section 32a and the second air heat exchange section 32b of the air heat exchanger 32 by a heat exchange connection pipe 10g. The heat exchange connection pipe 10g is provided with a check valve 16 that allows only the flow of the refrigerant from the four-way switching valve 11 to the air heat exchanger 32.

The bypass flow path 12 includes a water heat exchange low-stage bypass portion 41 that connects the water heat exchanger 31 and the low-stage compressor 3, and the water heat exchanger 31 without passing through the low-stage compressor 3. A water heat exchange high-stage bypass section 42 that connects the high-stage side compressor 4, an air heat exchange low-stage bypass section 43 that connects the air heat exchanger 32 and the low-stage side compressor 3, and a low-stage side compression. It has an air heat exchange high-stage bypass portion 44 that connects the air heat exchanger 32 and the high-stage side compressor 4 without going through the machine 3.

The water heat exchange low-stage bypass portion 41 is a pipe that connects the water heat exchanger 31 and the middle of the introduction pipe 10f extending from the port B of the four-way switching valve 11. The water heat exchange low-stage bypass portion 41 can introduce the refrigerant from the water heat exchanger 31 to the low-stage accumulator 3a of the low-stage side compressor 3.

The water heat exchange high-stage bypass portion 42 is a pipe 10 that branches from the middle of the water heat exchange low-stage bypass portion 41 and connects the water heat exchanger 31 and the high-stage accumulator 4a of the high-stage side compressor 4. The water heat exchange high-stage bypass portion 42 can directly introduce the refrigerant from the water heat exchanger 31 to the high-stage accumulator 4a.

The air heat exchange low-stage bypass portion 43 is a pipe that branches from the middle of the heat exchange connection pipe 10g and connects the air heat exchanger 32 and the low-stage accumulator 3a. As a result, the air heat exchange low-stage bypass portion 43 can introduce the refrigerant from the air heat exchanger 32 to the low-stage accumulator 3a. Therefore, the check valve 16 is located in four directions from the branch position of the air heat exchange low stage bypass portion 43 from the heat exchange connection pipe 10 g, that is, the connection point of the air heat exchange low stage bypass portion 43 with the heat exchange connection pipe 10 g. It is provided on the switching valve 11 side.

The air heat exchange high-stage bypass portion 44 is a pipe that branches from the middle of the heat exchange connection pipe 10g and connects the air heat exchanger 32 and the high-stage accumulator 4a. As a result, the air heat exchange high-stage bypass portion 44 can directly introduce the refrigerant from the air heat exchanger 32 to the high-stage accumulator 4a. In the present embodiment, the air heat exchange high-stage bypass portion 44 is branched from the heat exchange connection pipe 10 g on the side closer to the air heat exchanger 32 than the air heat exchange low-stage bypass portion 43. Therefore, the check valve 16 is located in four directions from the branch position of the air heat exchange high-stage bypass portion 44 from the heat exchange connection pipe 10 g, that is, the connection point of the air heat exchange high-stage bypass portion 44 with the heat exchange connection pipe 10 g. It is provided on the switching valve 11 side.

The on-off valve 13 is provided in the first valve 21 provided in the water heat exchange low stage bypass portion 41, the second valve 22 provided in the water heat exchange high stage bypass portion 42, and the air heat exchange low stage bypass portion 43. It has a third valve 23 provided and a fourth valve 24 provided in the air heat exchange high-stage bypass portion 44. Each valve 21, 22, 23, 24 is a two-way valve, and opens and closes the flow path of each bypass portion 41, 42, 43, 44.

The control unit 14 changes the flow direction of the refrigerant in the refrigerant circuit 2 by operating the expansion valve 6, the on-off valve 13, the four-way switching valve 11, and the valve device 15.

Here, the heat pump 1 of the present embodiment further includes a hot gas circuit 50.
The hot gas circuit 50 includes a heat exchanger inter-pipe pipe 51 connecting between the first air heat exchange unit 32a and the expansion valve 6a and between the second air heat exchange unit 32b and the expansion valve 6b, and the heat thereof. It has a hot gas pipe 52 branched from the heat exchanger pipe 51 and connected to the accumulator pipe 10c between the low-stage accumulator 3a and the four-way switching valve 11. That is, the hot gas circuit 50 is provided between the first air heat exchange unit 32a and the expansion valve 6a (and between the second air heat exchange unit 32b and the expansion valve 6b) and at the inlet of the low-stage compressor 3. Is provided so that communication is possible.

In the heat exchanger inter-pipe pipe 51, a fifth valve 25 and a check valve 27 are provided between the branch position of the hot gas pipe 52 from the heat exchanger inter-pipe pipe 51 and the first air heat exchange unit 32a. A sixth valve 26 and a check valve 27 are provided between the branch position of the hot gas pipe 52 from the heat exchanger inter-pipe pipe 51 and the second heat exchanger 32b. The fifth valve 25 and the sixth valve 26 are also operated by the control unit 14 to open and close the flow path of the heat exchanger inter-pipe pipe 51. The check valve 27 allows the refrigerant to flow from the first air heat exchange unit 32a and the second air heat exchange unit 32b to the hot gas pipe 52 through the heat exchanger inter-pipe pipe 51, and conversely, the first from the hot gas pipe 52. The gas does not flow to the air heat exchange section 32a and the second air heat exchange section 32b. The sixth valve 26 may be exactly the same as the fifth valve 25.

Next, a procedure for switching each valve by the control unit 14 when the heat pump 1 is operated according to the operation patterns 1 to 5 shown in FIGS. 1 to 5 will be described.

[Operation pattern 1]
As shown in FIG. 1, in the operation pattern 1, the control unit 14 operates the four-way switching valve 11 to communicate the port D and the port A. Further, the port B and the port C are communicated with each other. As a result, the refrigerant from the high-stage compressor 4 is introduced into the condenser 5, and the refrigerant from the evaporator 7 is introduced into the low-stage compressor 3. The flow path of the refrigerant in this case is the first path.

Further, the control unit 14 operates the first valve 21 to the fourth valve 24 to close the water heat exchange low stage bypass unit 41, close the water heat exchange high stage bypass unit 42, and close the air heat exchange low stage bypass unit 42. The portion 43 is opened, and the air heat exchange high-stage bypass portion 44 is closed. As a result, all the refrigerant from the air heat exchanger 32 is introduced into the low-stage accumulator 3a of the low-stage side compressor 3 without passing through the four-way switching valve 11. Then, the refrigerant from the air heat exchanger 32 is compressed by the low-stage compressor main body 3b, then further compressed by the high-stage compressor main body 4b, passes through the four-way switching valve 11, and is introduced into the condenser 5. The water heat exchanger 31 is not used in the operation pattern 1.

[Operation pattern 2]
As shown in FIG. 2, in the operation pattern 2, the control unit 14 operates the four-way switching valve 11 and sets the flow path of the refrigerant as the first path.

Further, the control unit 14 operates the first valve 21 to the fourth valve 24 to open the water heat exchange low stage bypass unit 41, close the water heat exchange high stage bypass unit 42, and air heat exchange low stage bypass. The portion 43 is opened, and the air heat exchange high-stage bypass portion 44 is closed. As a result, all the refrigerants from the water heat exchanger 31 and the air heat exchanger 32 are introduced into the low-stage accumulator 3a of the low-stage side compressor 3 without passing through the four-way switching valve 11. Then, the refrigerant is compressed by the low-stage compressor main body 3b, then further compressed by the high-stage compressor main body 4b, passes through the four-way switching valve 11, and is introduced into the condenser 5.
In the operation pattern 2, the temperature of the refrigerant flowing out from the water heat exchanger 31 and the temperature of the refrigerant flowing out from the air heat exchanger 32 are the same, and the temperature of the refrigerant flowing out from the water heat exchanger 31 and the temperature of the refrigerant flowing out from the water heat exchanger 31 This is performed when there is a temperature difference of a predetermined value or more between the temperature of the refrigerant flowing out of the air heat exchanger 32 and the temperature of the refrigerant flowing out of the condenser 5. Hereinafter, the “temperature of the refrigerant flowing out of the water heat exchanger 31” is the temperature of the refrigerant after the refrigerant flowing out from the first air heat exchange unit 32a and the refrigerant flowing out from the second air heat exchange unit 32b merge. Means.

[Operation pattern 3]
As shown in FIG. 3, in the operation pattern 3, the control unit 14 operates the four-way switching valve 11 and sets the flow path of the refrigerant as the first path.

Further, the control unit 14 operates the first valve 21 to the fourth valve 24 to close the water heat exchange low stage bypass unit 41, open the water heat exchange high stage bypass unit 42, and open the air heat exchange low stage bypass unit 42. The portion 43 is opened, and the air heat exchange high-stage bypass portion 44 is closed. As a result, the refrigerant from the water heat exchanger 31 is introduced into the high-stage accumulator 4a of the high-stage side compressor 4 without passing through the four-way switching valve 11 and the low-stage side compressor 3. Then, the refrigerant from the water heat exchanger 31 is compressed by the high-stage compressor main body 4b, passes through the four-way switching valve 11, and is introduced into the condenser 5. Further, all the refrigerant from the air heat exchanger 32 is introduced into the low-stage accumulator 3a of the low-stage side compressor 3 without passing through the four-way switching valve 11. Then, the refrigerant from the air heat exchanger 32 is compressed by the low-stage compressor main body 3b, then further compressed by the high-stage compressor main body 4b, passes through the four-way switching valve 11, and is introduced into the condenser 5.
The operation pattern 3 is implemented when the temperature of the refrigerant flowing out of the water heat exchanger 31 is higher than the temperature of the refrigerant flowing out of the air heat exchanger 32.

[Operation pattern 4]
As shown in FIG. 4, in the operation pattern 4, the control unit 14 operates the four-way switching valve 11 and sets the flow path of the refrigerant as the first path.

Further, the control unit 14 operates the first valve 21 to the fourth valve 24 to open the water heat exchange low stage bypass unit 41, close the water heat exchange high stage bypass unit 42, and air heat exchange low stage bypass. The portion 43 is closed, and the air heat exchange high-stage bypass portion 44 is closed. As a result, all the refrigerant from the water heat exchanger 31 is introduced into the low-stage accumulator 3a of the low-stage side compressor 3 without passing through the four-way switching valve 11. Then, the refrigerant from the water heat exchanger 31 is compressed by the low-stage compressor main body 3b, then further compressed by the high-stage compressor main body 4b, passes through the four-way switching valve 11, and is introduced into the condenser 5. The air heat exchanger 32 is not used in the operation pattern 4.

[Operation pattern 5]
As shown in FIG. 5, in the operation pattern 5, the control unit 14 operates the four-way switching valve 11 and sets the flow path of the refrigerant as the first path.

Further, the control unit 14 operates the first valve 21 to the fourth valve 24 to open the water heat exchange low stage bypass unit 41, close the water heat exchange high stage bypass unit 42, and air heat exchange low stage bypass. The portion 43 is closed, and the air heat exchange high-stage bypass portion 44 is opened. As a result, all the refrigerant from the water heat exchanger 31 is introduced into the low-stage accumulator 3a of the low-stage side compressor 3 without passing through the four-way switching valve 11. Then, the refrigerant from the water heat exchanger 31 is compressed by the low-stage compressor main body 3b, then further compressed by the high-stage compressor main body 4b, passes through the four-way switching valve 11, and is introduced into the condenser 5. Further, the refrigerant from the air heat exchanger 32 is introduced into the high-stage accumulator 4a without passing through the four-way switching valve 11 and the low-stage side compressor 3. Then, the refrigerant from the air heat exchanger 32 is compressed by the high-stage compressor main body 4b, passes through the four-way switching valve 11, and is introduced into the condenser 5.
The operation pattern 4 is implemented when the temperature of the refrigerant flowing out of the water heat exchanger 31 is smaller than the temperature of the refrigerant flowing out of the air heat exchanger 32.

Next, a procedure for switching each valve by the control unit 14 when the heat pump 1 is operated in the defrost operation patterns 1 and 2 shown in FIGS. 6 and 7 will be described.

[Defrost operation pattern 1]
As shown in FIG. 6, in the defrost operation pattern 1, the control unit 14 operates the four-way switching valve 11 to communicate the port D and the port C. Further, port B and port A are communicated with each other. As a result, the refrigerant from the high-stage compressor 4 is introduced into the evaporator 7, and the refrigerant from the condenser 5 is introduced into the low-stage compressor 3. The flow path of the refrigerant in this case is the second path.

Further, the control unit 14 operates the first valve 21 to the fourth valve 24 to close the water heat exchange low stage bypass unit 41, close the water heat exchange high stage bypass unit 42, and close the air heat exchange low stage bypass unit 42. The portion 43 is closed, and the air heat exchange high-stage bypass portion 44 is closed. As a result, the high-temperature and high-pressure refrigerant from the high-stage compressor 4 passes through the four-way switching valve 11 and is introduced into the air heat exchanger 32 through the heat exchange connection pipe 10 g and the check valve 16. Then, the refrigerant passes through the air heat exchanger 32 to defrost the air heat exchanger 32, and the refrigerant is sent to the expansion valves 6a and 6b provided in the first air heat exchange section 32a and the second air heat exchange section 32b. Inflows. After that, the refrigerant is introduced into the condenser 5, passes through the four-way switching valve 11, and is introduced into the low-stage accumulator 3a of the low-stage compressor 3. At this time, the water heat exchanger 31 is not used.

[Defrost operation pattern 2]
As shown in FIG. 7, in the defrost operation pattern 2, the control unit 14 operates the four-way switching valve 11 and sets the flow path of the refrigerant as the second path. Further, the control unit 14 operates the valve device 15 to close the connection pipe 10b.

Further, the control unit 14 operates the first valve 21 to the fourth valve 24 to open the water heat exchange low stage bypass unit 41, close the water heat exchange high stage bypass unit 42, and air heat exchange low stage bypass. The portion 43 is closed, and the air heat exchange high-stage bypass portion 44 is closed. As a result, the high-temperature and high-pressure refrigerant from the high-stage compressor 4 passes through the four-way switching valve 11 and is introduced into the air heat exchanger 32 through the heat exchange connection pipe 10 g. Then, when the refrigerant passes through the air heat exchanger 32, the air heat exchanger 32 is defrosted to the expansion valves 6a and 6b provided in the first air heat exchange unit 32a and the second air heat exchange unit 32b. The refrigerant flows in. After that, the refrigerant is introduced into the water heat exchanger 31 and introduced into the low stage accumulator 3a of the low stage side compressor 3 through the water heat exchange low stage bypass portion 41. At this time, the condenser 5 is not used.

[Hot gas operation pattern]
As shown in FIG. 8, in the hot gas operation pattern, the control unit 14 operates the four-way switching valve 11 and sets the flow path of the refrigerant as the second path. Further, the control unit 14 operates the expansion valves 6a and 6b to close the connection pipe 10b.

Further, the control unit 14 operates the first valve 21 to the fourth valve 24 to close the water heat exchange low stage bypass unit 41, close the water heat exchange high stage bypass unit 42, and close the air heat exchange low stage bypass unit 42. The portion 43 is closed, and the air heat exchange high-stage bypass portion 44 is closed. Further, the control unit 14 operates the fifth valve 25 and the sixth valve 26 to open the heat exchanger inter-heat exchanger piping 51. As a result, the high-temperature and high-pressure refrigerant from the high-stage compressor 4 passes through the four-way switching valve 11 and is introduced into the air heat exchanger 32 through the heat exchange connection pipe 10 g. Then, the refrigerant passes through the air heat exchanger 32 to defrost the air heat exchanger 32, and the refrigerant flows into the heat exchanger inter-pipe pipe 51. After that, the refrigerant is introduced into the low-stage accumulator 3a of the low-stage compressor 3 through the hot gas pipe 52. At this time, the air heat exchanger 32 and the water heat exchanger 31 are not used.

In the heat pump 1 of the present embodiment described above, the state of the refrigerant toward the low-stage compressor 3 and the high-stage compressor 4 due to the change in the heat exchange amount in the evaporator 7 and the change in the temperature of the refrigerant. However, there are cases where the optimum state for compression by the low-stage compressor 3 and the high-stage compressor 4 is not achieved. In particular, the evaporator 7 has an air heat exchanger 32 having a first air heat exchange unit 32a and a second air heat exchange unit 32b, and a water heat exchanger 31. Therefore, it is highly possible that the temperature of air or water, which is a medium for heat exchange, fluctuates due to changes in the environment, and the amount of heat exchange of the refrigerant also fluctuates.

By providing the bypass flow path 12 here, not only the refrigerant from the evaporator 7 is introduced into the low-stage compressor 3, but also the refrigerant from the evaporator 7 is bypassed by the low-stage compressor 3. It can be directly introduced into the high-stage compressor 4. Therefore, the path of the refrigerant can be switched to the compressor capable of optimum compression according to the state of the refrigerant flowing out from the evaporator 7. Therefore, the operating efficiency of the heat pump 1 can be improved.

Further, by providing the bypass flow path 12, the refrigerant from the evaporator 7 can be introduced directly into the low-stage compressor 3 or the high-stage compressor 4 without passing through the four-way switching valve 11. There is. Therefore, even if the heat pump has a four-way switching valve 11 and can change the flow path of the refrigerant, the bypass flow path 12 can introduce the refrigerant from the evaporator 7 into a compressor capable of optimum compression. It will be easier to add the

Further, by providing the control unit 14, the path of the refrigerant can be automatically switched so as to introduce the refrigerant into the compressor capable of optimum compression according to the state of the refrigerant flowing out from the evaporator 7.

Further, by providing the check valve 16 in the heat exchange connection pipe 10 g, the refrigerant is transferred from the air heat exchanger 32 via the bypass flow path 12 without passing through the four-way switching valve 11, respectively. All the refrigerant from the air heat exchanger 32 can be made to flow into the bypass flow path 12 (air heat exchange low-stage bypass section 43, air heat exchange high-stage bypass section 44). Therefore, the bypass flow path 12 can be fully functioned.

Further, in the configuration of the present embodiment, either the defrost operation pattern 1 or the defrost operation pattern 2 can be selected by the control unit 14. The defrost operation patterns 1 and 2 enable effective defrosting in a short time in the air heat exchanger 32. Further, the hot gas operation pattern can be selected by the control unit 14. By performing the hot gas operation, the refrigerant can circulate between the air heat exchanger 32 and the low-stage side compressor 3 and the high-stage side compressor 4 without passing through the condenser 5.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the configurations and combinations thereof in each embodiment are examples, and the configurations may be added or omitted within a range not deviating from the gist of the present invention. , Replacement, and other changes are possible. Further, the present invention is not limited to the embodiments, but only to the scope of claims. For example, if the temperature of the refrigerant flowing out of the condenser 5, the temperature of the refrigerant flowing out of the water heat exchanger 31, and the temperature of the refrigerant flowing out of the air heat exchanger 32 are equal, the control unit 14 However, the four-way switching valve 11 is made to select the first path, the first valve 21 closes the water heat exchange low-stage bypass portion 41, and the second valve 22 opens the water heat exchange high-stage bypass portion 42. The air heat exchange low-stage bypass portion 43 may be closed by the valve 23, and the air heat exchange high-stage bypass portion 44 may be opened by the fourth valve 24. By performing such an operation, the temperature of the refrigerant flowing out of the condenser 5, the temperature of the refrigerant flowing out of the water heat exchanger 31, and the temperature of the refrigerant flowing out of the air heat exchanger 32 are equivalent. In this case, the refrigerant from the water heat exchanger 31 can be directly introduced into the high-stage side compressor 4, and the refrigerant from the air heat exchanger 32 can be directly introduced into the high-stage side compressor 4. .. That is, each of the refrigerants of the refrigerant from the water heat exchanger 31 and the refrigerant from the air heat exchanger 32 is introduced into the compressor suitable for compression among the low-stage side compressor 3 and the high-stage side compressor 4. can.

For example, the control unit 14 does not necessarily have to be provided. In this case, each valve may be operated manually.

Further, the evaporator 7 is not limited to the case where the combination of the water heat exchanger 31 and the air heat exchanger 32 is provided, and the number of heat exchangers is not limited to the above case. For example, the evaporator 7 may not have the air heat exchanger 32 and may have two water heat exchangers in parallel.

Further, in the above-mentioned refrigerant circuit 2, various valves may be provided in addition to the above-mentioned various valves.

1 ... Heat pump 2 ... Refrigerant circuit 3 ... Low-stage compressor 3a ... Low-stage compressor 3b ... Low-stage compressor body 3c ... Low-stage oil separator 4 ... High-stage side compressor 4a ... High-stage accumulator 4b ... High-stage compressor Main body 4c ... High-stage oil separator 5 ... Compressor 6 ... Expansion parts 6a, 6b ... (Second) Expansion valve 6c ... (First) Expansion valve 7 ... Evaporator 10 ... Piping (flow path)
10a ... Interstage piping 10b ... Connection piping 10c ... Accumulator piping 10d ... Discharge piping 10e ... Condenser connection piping 10f ... Introduction piping 10g ... Heat exchange connection piping 11 ... Four-way switching valve 12 ... Bypass flow path 13 ... On / off valve 14 ... Control Part 15 ... Valve device 16 ... Check valve 21 ... First valve 22 ... Second valve 23 ... Third valve 24 ... Fourth valve 25 ... Fifth valve 26 ... Sixth valve 27 ... Check valve 31 ... Water heat exchange Vessel (first heat exchanger)
32 ... Air heat exchanger (second heat exchanger)
32a ... First air heat exchange unit 32b ... Second air heat exchange unit 41 ... Water heat exchange low stage bypass unit 42 ... Water heat exchange high stage bypass unit 43 ... Air heat exchange low stage bypass unit 44 ... Air heat exchange high stage Bypass 50 ... Hot gas circuit 51 ... Heat exchanger inter-pipe pipe 52 ... Hot gas pipe

Claims (13)

A low-stage compressor that compresses the refrigerant,
A high-stage compressor that further compresses the refrigerant from the low-stage compressor, and
A condenser that condenses the refrigerant from the high-stage compressor,
An expansion part that reduces the pressure of the refrigerant from the condenser,
An evaporator connected to the expansion portion to evaporate the refrigerant from the expansion portion,
The first path for introducing the refrigerant from the high-stage compressor into the condenser and introducing the refrigerant from the evaporator into the low-stage compressor, and the refrigerant from the high-stage compressor. A four-way switching valve capable of selecting a second path to be introduced into the evaporator and to introduce the refrigerant from the condenser into the low-stage compressor.
The refrigerant from the evaporator can be introduced into the low-stage compressor without passing through the four-way switching valve, and the evaporator does not pass through the four-way switching valve and the low-stage compressor. A bypass flow path that can selectively introduce the refrigerant of the above to the high-stage compressor, and
A heat pump equipped with. An on-off valve provided in the bypass flow path to open and close the bypass flow path,
A control unit that operates the on-off valve and the four-way switching valve,
The heat pump according to claim 1. The evaporator is
A first heat exchanger that exchanges heat between the refrigerant and the first heat medium,
A second heat exchanger, which is provided in parallel with the first heat exchanger and exchanges heat between the refrigerant and the second heat medium,
Have,
The bypass flow path is
The first heat exchange low-stage bypass section that connects the first heat exchanger and the low-stage compressor,
A first heat exchange high-stage bypass section that connects the first heat exchanger and the high-stage compressor without going through the low-stage compressor.
A second heat exchange low-stage bypass section connecting the second heat exchanger and the low-stage compressor,
A second heat exchange high-stage bypass section that connects the second heat exchanger and the high-stage compressor without going through the low-stage compressor.
Have,
The on-off valve
The first valve provided in the first heat exchange low-stage bypass part,
The second valve provided in the first heat exchange high-stage bypass portion and
The third valve provided in the second heat exchange low-stage bypass portion and
The fourth valve provided in the second heat exchange high-stage bypass section and
The heat pump according to claim 2. A flow path connecting the second heat exchanger and the four-way switching valve is provided.
The second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion are provided so as to branch from the flow path.
It is provided on the four-way switching valve side in the flow path from the branch position of the second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion from the flow path, and the four-way switching valve is used to display the second. (Ii) The heat pump according to claim 3, further comprising a check valve that allows only the flow of refrigerant toward the heat exchanger. The control unit causes the four-way switching valve to select the second path, and operates the first valve, the second valve, the third valve, and the fourth valve to close the bypass flow path. The heat pump according to claim 4, wherein the refrigerant from the high-stage compressor is introduced into the second heat exchanger via the check valve. A valve device is further provided between the condenser and the inflatable portion.
The control unit operates the valve device to stop the flow of the refrigerant from the condenser to the expansion unit, causes the four-way switching valve to select the second path, and operates the first valve. The first heat exchange low-stage bypass section is opened, and the second valve, the third valve, and the fourth valve are operated to operate the first heat exchange high-stage bypass section and the second heat exchange low. The heat pump according to claim 4, which closes the stage bypass portion and the second heat exchange high stage bypass portion. The expanded portion is
A first expansion valve provided at the inlet of the first heat exchanger between the condenser and the first heat exchanger,
A second expansion valve arranged in parallel with the first expansion valve and provided at the inlet of the second heat exchanger between the condenser and the second heat exchanger.
Have,
A hot gas circuit provided so as to allow communication between the second heat exchanger and the second expansion valve and the inlet of the lower stage compressor.
The fifth valve provided in the hot gas circuit and
A check valve provided in the hot gas circuit that allows only the flow of refrigerant from the inlet of the second heat exchanger to the inlet of the lower stage compressor.
Further prepare
The control unit operates the second expansion valve to stop the flow of the refrigerant from the condenser to the second expansion valve, and operates the fifth valve to open the hot gas circuit. The heat pump according to claim 5, wherein the refrigerant from the second heat exchanger is introduced into the low-stage compressor via the check valve. The control unit
Let the four-way switching valve select the first path.
When the temperature of the refrigerant flowing out of the first heat exchanger is lower than the temperature of the refrigerant flowing out of the second heat exchanger, the first valve opens the first heat exchange low-stage bypass portion. The second valve closes the first heat exchange high-stage bypass portion, the third valve closes the second heat exchange low-stage bypass portion, and the fourth valve closes the second heat exchange high-stage. Open the bypass part and
When the temperature of the refrigerant flowing out of the first heat exchanger is higher than the temperature of the refrigerant flowing out of the second heat exchanger, the first valve closes the first heat exchange low-stage bypass portion. The second valve opens the first heat exchange high-stage bypass portion, the third valve opens the second heat exchange low-stage bypass portion, and the fourth valve opens the second heat exchange high-stage. The heat pump according to any one of claims 4 to 7, which closes the bypass portion. The control unit
Let the four-way switching valve select the first path.
When the temperature of the refrigerant flowing out of the condenser, the temperature of the refrigerant flowing out of the first heat exchanger, and the temperature of the refrigerant flowing out of the second heat exchanger are equal, the first. The first heat exchange low-stage bypass portion is closed by the valve, the first heat exchange high-stage bypass portion is opened by the second valve, and the second heat exchange low-stage bypass portion is closed by the third valve. The heat pump according to any one of claims 4 to 8, wherein the second heat exchange high-stage bypass portion is opened by the fourth valve. The control unit
Let the four-way switching valve select the first path.
The temperature of the refrigerant flowing out of the first heat exchanger and the temperature of the refrigerant flowing out of the second heat exchanger are equal to each other, and the temperature of the refrigerant flowing out of the first heat exchanger and the first heat exchanger. (Ii) If there is a temperature difference between the temperature of the refrigerant flowing out of the heat exchanger and the temperature of the refrigerant flowing out of the condenser, the first valve opens the first heat exchange low-stage bypass portion. The second valve closes the first heat exchange high-stage bypass portion, the third valve opens the second heat exchange low-stage bypass portion, and the fourth valve opens the second heat exchange. The heat pump according to any one of claims 4 to 9, which closes the high-stage bypass portion. A low-stage compressor that compresses the refrigerant,
A high-stage compressor that further compresses the refrigerant from the low-stage compressor, and
A condenser that condenses the refrigerant from the high-stage compressor,
An expansion part that reduces the pressure of the refrigerant from the condenser,
An evaporator connected to the expansion portion to evaporate the refrigerant from the expansion portion,
The first path for introducing the refrigerant from the high-stage compressor into the condenser and introducing the refrigerant from the evaporator into the low-stage compressor, and the refrigerant from the high-stage compressor. A four-way switching valve capable of selecting a second path to be introduced into the evaporator and to introduce the refrigerant from the condenser into the low-stage compressor.
The refrigerant from the evaporator can be introduced into the low-stage compressor without passing through the four-way switching valve, or the high-stage compressor can be introduced without passing through the four-way switching valve and the low-stage compressor. Bypass flow path that can be introduced into the side compressor,
An on-off valve provided in the bypass flow path to open and close the bypass flow path,
Equipped with
The evaporator is
A first heat exchanger that exchanges heat between the refrigerant and the first heat medium,
A second heat exchanger, which is provided in parallel with the first heat exchanger and exchanges heat between the refrigerant and the second heat medium,
Have,
The bypass flow path is
The first heat exchange low-stage bypass section that connects the first heat exchanger and the low-stage compressor,
A first heat exchange high-stage bypass section that connects the first heat exchanger and the high-stage compressor without going through the low-stage compressor.
A second heat exchange low-stage bypass section connecting the second heat exchanger and the low-stage compressor,
A second heat exchange high-stage bypass section that connects the second heat exchanger and the high-stage compressor without going through the low-stage compressor.
Have,
The on-off valve
The first valve provided in the first heat exchange low-stage bypass part,
The second valve provided in the first heat exchange high-stage bypass portion and
The third valve provided in the second heat exchange low-stage bypass portion and
The fourth valve provided in the second heat exchange high-stage bypass section and
Have,
Further provided with a flow path connecting the second heat exchanger and the four-way switching valve.
The second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion are provided so as to branch from the flow path.
It is provided on the four-way switching valve side in the flow path from the branch position of the second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion from the flow path, and the four-way switching valve is used to display the second. (Ii) A method for controlling a heat pump that further includes a check valve that allows only the flow of refrigerant toward the heat exchanger.
Let the four-way switching valve select the first path.
When the temperature of the refrigerant flowing out of the first heat exchanger is lower than the temperature of the refrigerant flowing out of the second heat exchanger, the first valve opens the first heat exchange low-stage bypass portion. The second valve closes the first heat exchange high-stage bypass portion, the third valve closes the second heat exchange low-stage bypass portion, and the fourth valve closes the second heat exchange high-stage. Open the bypass part and
When the temperature of the refrigerant flowing out of the first heat exchanger is higher than the temperature of the refrigerant flowing out of the second heat exchanger, the first valve closes the first heat exchange low-stage bypass portion. The second valve opens the first heat exchange high-stage bypass portion, the third valve opens the second heat exchange low-stage bypass portion, and the fourth valve opens the second heat exchange high-stage. A heat pump control method that closes the bypass section. A low-stage compressor that compresses the refrigerant,
A high-stage compressor that further compresses the refrigerant from the low-stage compressor, and
A condenser that condenses the refrigerant from the high-stage compressor,
An expansion part that reduces the pressure of the refrigerant from the condenser,
An evaporator connected to the expansion portion to evaporate the refrigerant from the expansion portion,
The first path for introducing the refrigerant from the high-stage compressor into the condenser and introducing the refrigerant from the evaporator into the low-stage compressor, and the refrigerant from the high-stage compressor. A four-way switching valve capable of selecting a second path to be introduced into the evaporator and to introduce the refrigerant from the condenser into the low-stage compressor.
The refrigerant from the evaporator can be introduced into the low-stage compressor without passing through the four-way switching valve, or the high-stage compressor can be introduced without passing through the four-way switching valve and the low-stage compressor. Bypass flow path that can be introduced into the side compressor,
An on-off valve provided in the bypass flow path to open and close the bypass flow path,
Equipped with
The evaporator is
A first heat exchanger that exchanges heat between the refrigerant and the first heat medium,
A second heat exchanger, which is provided in parallel with the first heat exchanger and exchanges heat between the refrigerant and the second heat medium,
Have,
The bypass flow path is
The first heat exchange low-stage bypass section that connects the first heat exchanger and the low-stage compressor,
A first heat exchange high-stage bypass section that connects the first heat exchanger and the high-stage compressor without going through the low-stage compressor.
A second heat exchange low-stage bypass section connecting the second heat exchanger and the low-stage compressor,
A second heat exchange high-stage bypass section that connects the second heat exchanger and the high-stage compressor without going through the low-stage compressor.
Have,
The on-off valve
The first valve provided in the first heat exchange low-stage bypass part,
The second valve provided in the first heat exchange high-stage bypass portion and
The third valve provided in the second heat exchange low-stage bypass portion and
The fourth valve provided in the second heat exchange high-stage bypass section and
Have,
Further provided with a flow path connecting the second heat exchanger and the four-way switching valve.
The second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion are provided so as to branch from the flow path.
It is provided on the four-way switching valve side in the flow path from the branch position of the second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion from the flow path, and the four-way switching valve is used to display the second. (Ii) A method for controlling a heat pump that further includes a check valve that allows only the flow of refrigerant toward the heat exchanger.
Let the four-way switching valve select the first path.
When the temperature of the refrigerant flowing out of the condenser, the temperature of the refrigerant flowing out of the first heat exchanger, and the temperature of the refrigerant flowing out of the second heat exchanger are equal, the first. The first heat exchange low-stage bypass portion is closed by the valve, the first heat exchange high-stage bypass portion is opened by the second valve, and the second heat exchange low-stage bypass portion is closed by the third valve. A method for controlling a heat pump that opens the second heat exchange high-stage bypass portion by the fourth valve. A low-stage compressor that compresses the refrigerant,
A high-stage compressor that further compresses the refrigerant from the low-stage compressor, and
A condenser that condenses the refrigerant from the high-stage compressor,
An expansion part that reduces the pressure of the refrigerant from the condenser,
An evaporator connected to the expansion portion to evaporate the refrigerant from the expansion portion,
The first path for introducing the refrigerant from the high-stage compressor into the condenser and introducing the refrigerant from the evaporator into the low-stage compressor, and the refrigerant from the high-stage compressor. A four-way switching valve capable of selecting a second path to be introduced into the evaporator and to introduce the refrigerant from the condenser into the low-stage compressor.
The refrigerant from the evaporator can be introduced into the low-stage compressor without passing through the four-way switching valve, or the high-stage compressor can be introduced without passing through the four-way switching valve and the low-stage compressor. Bypass flow path that can be introduced into the side compressor,
An on-off valve provided in the bypass flow path to open and close the bypass flow path,
Equipped with
The evaporator is
A first heat exchanger that exchanges heat between the refrigerant and the first heat medium,
A second heat exchanger, which is provided in parallel with the first heat exchanger and exchanges heat between the refrigerant and the second heat medium,
Have,
The bypass flow path is
The first heat exchange low-stage bypass section that connects the first heat exchanger and the low-stage compressor,
A first heat exchange high-stage bypass section that connects the first heat exchanger and the high-stage compressor without going through the low-stage compressor.
A second heat exchange low-stage bypass section connecting the second heat exchanger and the low-stage compressor,
A second heat exchange high-stage bypass section that connects the second heat exchanger and the high-stage compressor without going through the low-stage compressor.
Have,
The on-off valve
The first valve provided in the first heat exchange low-stage bypass part,
The second valve provided in the first heat exchange high-stage bypass portion and
The third valve provided in the second heat exchange low-stage bypass portion and
The fourth valve provided in the second heat exchange high-stage bypass section and
Have,
Further provided with a flow path connecting the second heat exchanger and the four-way switching valve.
The second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion are provided so as to branch from the flow path.
It is provided on the four-way switching valve side in the flow path from the branch position of the second heat exchange low-stage bypass portion and the second heat exchange high-stage bypass portion from the flow path, and the four-way switching valve is used to display the first. (Ii) A method for controlling a heat pump that further includes a check valve that allows only the flow of refrigerant toward the heat exchanger.
Let the four-way switching valve select the first path.
The temperature of the refrigerant flowing out of the first heat exchanger and the temperature of the refrigerant flowing out of the second heat exchanger are equal to each other, and the temperature of the refrigerant flowing out of the first heat exchanger and the first heat exchanger. (Ii) If there is a temperature difference between the temperature of the refrigerant flowing out of the heat exchanger and the temperature of the refrigerant flowing out of the condenser, the first valve opens the first heat exchange low-stage bypass portion. The second valve closes the first heat exchange high-stage bypass portion, the third valve opens the second heat exchange low-stage bypass portion, and the fourth valve opens the second heat exchange. A heat pump control method that closes the high-stage bypass section.

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