JP5448897B2 - Water heater - Google Patents

Description

  The present invention relates to a heat pump type water heater.

A heat pump type water heater is a heat exchanger that heats water by exchanging heat between the refrigerant circulating in the refrigeration cycle and the water flowing through the water cycle in a water heat exchanger. It is attracting attention for its energy saving in comparison.
In order to improve the efficiency of the heat pump type water heater, it is important to improve the heat exchange efficiency in the water heat exchanger, and to improve the efficiency of the refrigeration cycle, in particular, the compressor that compresses the refrigerant.

Various things which improve the heat exchange efficiency in a water heat exchanger, such as what is shown by patent document 1, are proposed, for example.
What is shown in Patent Document 1 is that which branches a part of the circulating refrigerant, injects all of it into the compressor, increases the amount of refrigerant discharged from the compressor, and increases the amount of water heated It is.
In addition, it is known to use a compressor having a two-stage (or multistage) compression mechanism in order to improve the efficiency of the compressor.

It can be expected that the efficiency of the water heater will be improved by using a two-stage compressor and using the injection together to increase the efficiency and capacity of the compressor.
The injection in the two-stage compressor is performed by, for example, branching a part of the refrigerant from the water heat exchanger, depressurizing it, and heating it with the main-stream refrigerant passing through one of the double pipe heat exchangers. And an intermediate pressure portion that is between the high-stage compression mechanism.
The two-stage compressor has an optimum compression ratio (ratio of displacement amounts) between the low-stage side compression mechanism and the high-stage side compression mechanism. When injection is used, this compression ratio is designed to be efficient at intermediate pressure after injection.

JP 2008-256281 A

By the way, in the water heat exchanger, since the gas refrigerant discharged from the compressor and the water in the water cycle are generally opposed to each other, the temperature of the refrigerant coming out of the water heat exchanger is introduced into the water heat exchanger. Will approach the temperature of the water. The temperature of the water introduced into the water heat exchanger varies greatly depending on the season and operating conditions.
For example, when injection is performed using the above-described double pipe heat exchanger, if the water temperature at the inlet side of the water heat exchanger becomes low, the refrigerant temperature at the outlet side of the refrigerant circuit decreases, so The temperature of the refrigerant introduced into the exchanger decreases. For this reason, since the temperature of the refrigerant for injection heated by the double pipe heat exchanger is also lowered, the pressure becomes smaller than the pressure of the intermediate pressure portion in the two-stage compressor. For this reason, since the injection cannot be performed, the compressor is in a pure two-stage compression state.
As a result, the compression ratio between the low-stage side and the high-stage side in the two-stage compressor changes, and the optimal compression ratio that has been set is destroyed, resulting in a decrease in the efficiency of the two-stage compressor and a decrease in performance. .

  In view of such circumstances, the present invention can suppress a significant decrease in compressor performance even when the temperature of the water introduced into the water heat exchanger decreases, and can perform an efficient operation over a wide range of conditions. The purpose is to provide a water heater.

In order to solve the above problems, the present invention employs the following means.
That is, according to one aspect of the present invention, a two-stage compressor having an injection port between a low stage and a high stage, a first radiator, a second radiator, a main flow rate adjustment valve, and an evaporator are sequentially provided by a refrigerant pipe. Heat exchange between the refrigeration cycle connected so that the refrigerant flows and water flowing from the second radiator through the first radiator and flowing through the first radiator and the second radiator water cycle with a water pipe that is, the branch pipe connecting the confluence between the branch point and the main flow control valve and the evaporator between the first radiator and the second radiator in the refrigerant pipe the a injection circuit having the injection pipe for supplying coolant to the injection port from the branch pipe, a first valve member to flow selectively the refrigerant into the branch pipe, and the second radiator mains A first one-way pipe that is branched from between the quantity adjusting valve and that can supply the refrigerant only toward the upstream side of the injection pipe in the branch pipe, and the refrigerant selectively to the first one-way pipe. And a second valve member for flowing water.

In the water heater according to this aspect, the high-temperature and high-pressure refrigerant from the two-stage compressor flows from the first radiator (water heat exchanger) to the second radiator (water heat exchanger). The water flowing through the water cycle is heated by exchanging heat with the high-temperature and high-pressure refrigerant while flowing from the second radiator through the first radiator. On the other hand, the refrigerant cooled by the water flowing through the water cycle is throttled by the main flow rate adjusting valve to a low pressure and introduced into the evaporator. The refrigerant is cooled to a low temperature and a low pressure by an evaporator, and introduced into a two-stage compressor to a high temperature and a high pressure.
At this time, a part of the refrigerant is branched from the branch point between the first radiator and the second radiator by the injection circuit, and merges at the junction between the main flow rate adjusting valve and the evaporator, and the refrigerant flows into the injection port. Supplied.

Since the refrigerant passing through the first radiator exchanges heat with the water heated by the second radiator, the outlet of the first radiator even when the temperature of the water introduced into the second radiator is low The refrigerant temperature is relatively high. Thereby, since the temperature fall of the refrigerant | coolant injected is suppressed, it can prevent that the pressure becomes smaller than the pressure of the intermediate pressure part in a two-stage compressor.
Therefore, since injection can be performed, the intermediate pressure of the compressor can be adjusted to some extent, and a decrease in efficiency of the two-stage compressor under conditions where the incoming water temperature is low can be avoided. Even if the temperature of the water introduced into the second radiator decreases, a significant decrease in compressor performance can be suppressed, and an efficient operation can be performed over a wide range of conditions.
The sizes of the first radiator and the second radiator are preferably determined depending on how many times the refrigerant outlet temperature of the first radiator is set.

In the embodiment, the branch pipe, through one tube section and the branch flow adjusting valve of the double pipe heat exchanger and connecting the joining point and the branch point, the injection pipe, the said branch pipe 2 branched from the upstream side of the heavy-tube heat exchanger, it may be configuration that is connected to the through within the other tube of the injection expansion valve and the double pipe heat exchanger injection port.

A part of the refrigerant from the first radiator is branched at a branch point, flows through the branch pipe, passes through the inside of one pipe of the double pipe heat exchanger and the branch flow rate adjusting valve, and flows to the junction. At this time, a part of the refrigerant passing through the branch pipe is introduced into the injection pipe branched from the upstream side of the double pipe heat exchanger of the branch pipe. The refrigerant branched into the injection pipe is expanded by the injection expansion valve, and when passing through the other pipe of the double pipe heat exchanger, the refrigerant is heated by the refrigerant passing through the inside of the one pipe and supplied to the injection port.
On the other hand, since the refrigerant joining through the branch pipe is cooled, the temperature difference from the refrigerant passing through the second heat radiating pipe can be reduced.
Further, since the branch flow rate adjusting valve is installed in the branch pipe, the amount of refrigerant flowing in the branch pipe can be adjusted by adjusting the opening degree of the main flow rate adjusting valve and the branch flow rate adjusting valve.

One aspect of the present invention is such that the injection pipe in the branch pipe is branched from between the first valve member for selectively flowing the refrigerant to the branch pipe, the second radiator, and the main flow rate adjusting valve. a first one-way pipe capable of supplying the refrigerant only toward the upstream side of the second valve member to flow selectively the refrigerant into said first unidirectional pipes, is that feature.

If it does in this way, the refrigerant which came out of the 1st radiator by switching the 1st valve member can be made to flow either into the branch piping. Further, by switching the second valve member, a part of the refrigerant exiting the second radiator can be supplied or not supplied to the upstream side of the injection pipe in the branch pipe.
For example, when the temperature of the water introduced into the second radiator is low, the first valve member is operated so that the refrigerant flows through the branch pipe, and a relatively high-temperature refrigerant is supplied to the branch pipe. To do. Thereby, since the temperature fall of the refrigerant | coolant injected is suppressed, it can prevent that the pressure becomes smaller than the pressure of the intermediate pressure part in a two-stage compressor. Since the injection can be performed in this way, the intermediate pressure of the compressor can be adjusted to some extent, and a decrease in the efficiency of the two-stage compressor under a condition where the incoming water temperature is low can be avoided.
At this time, since the first one-way pipe can supply the refrigerant only toward the upstream side of the injection pipe, the refrigerant supplied to the branch pipe does not flow.

Further, when the temperature of water introduced into the second radiator is normal or high, the first valve member is operated so that the refrigerant does not flow into the branch pipe, and the second valve member is moved to the first valve member. Operate to branch into one-way piping. Part of the refrigerant exiting the second radiator is supplied to the upstream side of the injection pipe in the branch pipe through the first one-way pipe. Since the refrigerant exiting the first radiator is supplied to the injection pipe as compared with the refrigerant supplied to the injection pipe, the refrigeration cycle performance (COP) is deteriorated. Can be suppressed.
In this way, even if the temperature of the water introduced into the second radiator is lowered or raised, a significant decline in compressor performance or refrigeration cycle performance can be suppressed, and the efficiency can be improved over a wide range of conditions. Good driving can be done.

In this case, the first valve member is a three-way valve installed in the branch point, said second valve member includes a said second radiator in refrigerant piping the main flow control valve it may be a installed three-way valve between.
The first valve member may be an on-off valve such as an electromagnetic valve that opens and closes a branch pipe installed on the upstream side of the first one-way pipe in the branch pipe. The second valve member may be an on-off valve such as an electromagnetic valve that opens and closes the first one-way pipe installed in the first one-way pipe.

  In the above aspect, the injection circuit is provided with a branch expansion valve in a branch pipe from the branch point and a receiver for separating gas and liquid, and a liquid refrigerant separated by the receiver is introduced into the junction. The gaseous refrigerant separated by the receiver may be introduced into the injection port.

If it does in this way, some refrigerants which came out of the 1st radiator will be introduced into branch piping. The refrigerant introduced into the branch pipe is decompressed by the branch expansion valve, and a saturated liquid and a saturated gas are generated by the pressure and temperature. The saturated liquid and the saturated gas are introduced into the receiver and separated, the gaseous refrigerant is introduced into the injection port, and the liquid refrigerant is supplied to the junction, so that the gaseous liquid is reliably supplied to the injection port of the two-stage compressor. The refrigerant can be supplied.
Since the refrigerant passing through the first radiator exchanges heat with the water heated by the second radiator, the outlet of the first radiator even when the temperature of the water introduced into the second radiator is low The refrigerant temperature is relatively high. Thereby, since the temperature fall of the refrigerant | coolant injected is suppressed, it can prevent that the pressure becomes smaller than the pressure of the intermediate pressure part in a two-stage compressor.
Therefore, since injection can be performed, the intermediate pressure of the compressor can be adjusted to some extent, and a decrease in efficiency of the two-stage compressor under conditions where the incoming water temperature is low can be avoided. Even if the temperature of the water introduced into the second radiator decreases, a significant decrease in compressor performance can be suppressed, and an efficient operation can be performed over a wide range of conditions.

  In the above configuration, a third valve member that selectively flows the refrigerant to the branch pipe, a branch from between the second radiator and the main flow rate adjusting valve, and upstream of the injection pipe in the branch pipe A second one-way pipe that can supply the refrigerant only toward the second direction and a fourth valve member that selectively allows the refrigerant to flow to the second one-way pipe may be provided.

If it does in this way, the refrigerant which came out of the 1st radiator by switching a 3rd valve member can be made to flow either to flow into a branch piping. Further, by switching the fourth valve member, it is possible to supply or not supply a part of the refrigerant exiting the second radiator to the upstream side of the injection pipe in the branch pipe.
For example, when the temperature of the water introduced into the second radiator is low, the third valve member is operated so that the refrigerant flows through the branch pipe, and a relatively high-temperature refrigerant is supplied to the branch pipe. To do. Thereby, since the temperature fall of the refrigerant | coolant injected is suppressed, it can prevent that the pressure becomes smaller than the pressure of the intermediate pressure part in a two-stage compressor. Since the injection can be performed in this way, the intermediate pressure of the compressor can be adjusted to some extent, and a decrease in the efficiency of the two-stage compressor under a condition where the incoming water temperature is low can be avoided.
At this time, since the second one-way pipe can supply the refrigerant only toward the upstream side of the injection pipe, the refrigerant supplied to the branch pipe does not flow.

When the temperature of the water introduced into the second radiator is normal or high, the third valve member is operated so that the refrigerant does not flow through the branch pipe, and the fourth valve member is Operate to branch into one-way piping. Part of the refrigerant exiting the second radiator is supplied to the upstream side of the injection pipe in the branch pipe through the second one-way pipe. Since the refrigerant exiting the first radiator is supplied to the injection pipe as compared with the refrigerant supplied to the injection pipe, the refrigeration cycle performance (COP) is deteriorated. Can be suppressed.
In this way, even if the temperature of the water introduced into the second radiator is lowered or raised, a significant decline in compressor performance or refrigeration cycle performance can be suppressed, and the efficiency can be improved over a wide range of conditions. Good driving can be done.

In this case, the third valve member is a third three-way valve installed at the branch point, and the fourth valve member is the second radiator and the main flow rate adjustment in the refrigerant pipe. It may be a fourth three-way valve installed between the valves.
The third valve member may be an on-off valve such as an electromagnetic valve that opens and closes the branch pipe installed on the upstream side of the second one-way pipe in the branch pipe. The fourth valve member may be an on-off valve such as an electromagnetic valve that opens and closes the first one-way pipe installed in the second one-way pipe.

  According to the present invention, a part of the refrigerant exiting the first radiator is branched from the branch point between the first radiator and the second radiator, and joins at the junction between the main flow rate adjusting valve and the evaporator. At the same time, since the refrigerant is supplied to the injection port, even if the temperature of the water introduced into the second radiator decreases, it is possible to suppress a significant decrease in the compressor performance and perform an efficient operation over a wide range of conditions. be able to.

It is a block diagram which shows the circuit structure of the water heater concerning 1st embodiment of this invention. It is a block diagram which shows the circuit structure of the water heater concerning 2nd embodiment of this invention. It is a block diagram which shows the circuit structure of the water heater concerning 3rd embodiment of this invention. It is a block diagram which shows the circuit structure of the water heater concerning 4th embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[First embodiment]
Hereinafter, a heat pump type water heater 1 according to a first embodiment of the present invention will be described with reference to FIG.
FIG. 1 is a block diagram showing a circuit configuration of a water heater 1 according to the first embodiment.

The water heater 1 is provided with a refrigeration cycle 3 that serves as a heating source and a water cycle 5 that generates hot water.
The refrigeration cycle 3 includes a two-stage compressor 7 that compresses the refrigerant into a high-temperature / high-pressure refrigerant, and a first gas cooler (first radiator) 9 that cools the high-temperature / high-pressure refrigerant from the two-stage compressor 7. And a second gas cooler (second radiator) 11, a first flow rate adjustment valve (main flow rate adjustment valve) 13 that squeezes and depressurizes the cooled refrigerant from the second gas cooler 11, and cools the reduced refrigerant. An air heat exchanger (evaporator) 15 for gasification, an accumulator 17 that supplies gas refrigerant to the two-stage compressor 7 by performing gas-liquid separation, the two-stage compressor, the first gas cooler 9, and the second gas cooler 11, a first flow rate adjustment valve 13, an air heat exchanger 15, and a refrigerant pipe 19 that connects the accumulator 17 in this order. Carbon dioxide (CO ₂ ) is used as the refrigerant.

The two-stage compressor 7 includes a low-stage side compression mechanism and a high-stage side compression mechanism (not shown), and further compresses the intermediate-pressure refrigerant compressed by the low-stage side compression mechanism by the high-stage side compression mechanism. Are discharged. As the low-stage compression mechanism and the high-stage compression mechanism, those having a known structure such as a rolling piston type or swing type rotary compression mechanism and scroll compression mechanism are used.
The intermediate pressure portion of the two-stage compressor 7 is provided with an injection port P through which a part of the circulating refrigerant is injected. The injection decreases the temperature of the intermediate pressure portion and increases the amount of refrigerant, thereby increasing the amount of refrigerant discharged from the two-stage compressor 7.

  The refrigeration cycle 3 is provided with an injection circuit 21. The injection circuit 21 branches from a branch point A located between the first gas cooler 9 and the second gas cooler 11 in the refrigerant pipe 19, passes through the inside of one pipe of the double pipe heat exchanger 25, and the first in the refrigerant pipe 19. A branch pipe 23 that joins a junction B located between the flow rate adjusting valve 13 and the air heat exchanger 15, and a branch pipe 23 that branches from the upstream side of the double pipe heat exchanger 25. An injection pipe 29 that is connected to the injection port P of the two-stage compressor 7 through the other pipe of the pipe heat exchanger 25 is provided. The branch pipe 23 is provided with a second flow rate adjustment valve (branch flow rate adjustment valve) 31 on the downstream side of the double pipe heat exchanger 25.

The first gas cooler 9 and the second gas cooler 11 exchange heat between the refrigerant and water circulating in a water cycle 5 described later, and heat the water by radiating heat from the refrigerant to the water, thereby cooling the refrigerant. is there.
The refrigerant passing through the evaporator 15 is heat-exchanged with air blown by an evaporator fan (not shown), and absorbs heat from the air to be evaporated.
The second flow rate adjustment valve 31 has a function of reducing the pressure by restricting the refrigerant passing through the branch pipe 23. Further, the ratio of the refrigerant amount passing through the second gas cooler 11 and the refrigerant amount passing through the branch pipe 23 can be adjusted by adjusting the opening degree of the first flow rate adjustment valve 13 and the second flow rate adjustment valve 31.

The water cycle 5 includes a heat storage tank 33 that stores water, a water supply pump 35 that supplies water, a second gas cooler 11, a first gas cooler 9, and a heat storage tank 33, a water supply pump 35, a second gas cooler 11, A water pipe 37 is provided that forms a circulation flow path that returns to the heat storage tank 33 through the one gas cooler 9.
By the operation of the water supply pump 35, the water in the heat storage tank 33 passes through the second gas cooler 11 and the first gas cooler 9 in this order, and the first gas cooler 9 and the second gas cooler 11 always flow with the refrigerant flowing in the order of the first gas cooler 9 and the second gas cooler 11. It is designed to be a counter flow.

Operation | movement of the water heater 1 concerning this embodiment comprised as mentioned above is demonstrated.
In the refrigeration cycle 3, the supercritical refrigerant compressed by the two-stage compressor 7 to a high temperature and high pressure flows through the first gas cooler 9 and the second gas cooler 11 through the refrigerant pipe 19. On the other hand, in the water cycle 5, the water in the heat storage tank 33 flows in the order of the second gas cooler 11 and the first gas cooler 9 through the water pipe 37 by the operation of the water supply pump 35. During this time, the water flowing through the water pipe 37 is heated by heat exchange with the high-temperature and high-pressure refrigerant flowing through the refrigerant pipe 19 and returned to the heat storage tank 33. The heated water (hot water) stored in the heat storage tank 33 is sent to a place where it is separately required and used. In addition, you may make it supply the water which left the 1st gas cooler 9 to the place where it is needed directly, without returning to the thermal storage tank 33. FIG.

  On the other hand, the cooled high-pressure refrigerant cooled by the water passing through the water pipe 37 in the first gas cooler 9 and the second gas cooler 11 is depressurized by the first flow rate adjustment valve 13, and the low-temperature low-pressure gas-liquid two-phase refrigerant and Then, the air heat exchanger 15 exchanges heat with external air to evaporate and vaporize. The refrigerant vaporized by the air heat exchanger 15 is separated from gas and liquid by the accumulator 17. The vaporized refrigerant that has been gas-liquid separated by the accumulator 17 is again introduced into the two-stage compressor 7 and compressed.

At this time, a part of the refrigerant exiting the first gas cooler 9 is branched at the branch point A, passes through the branch pipe 23, passes through the one pipe inside the double pipe heat exchanger 25 and the second flow rate adjustment valve 31, It flows to the junction B.
A part of the refrigerant passing through the branch pipe 23 is introduced into the injection pipe 29 branched from the upstream side of the double pipe heat exchanger 17 of the branch pipe 23. The refrigerant branched into the injection pipe 29 is expanded by the injection expansion valve 27, and when passing through the other pipe inside the double pipe heat exchanger 25, the refrigerant is heated by the refrigerant passing through one pipe and supplied to the injection port P. The

On the other hand, the refrigerant that merges through the branch pipe 23 is cooled by the injected refrigerant that is expanded by the injection expansion valve 27 in the double pipe heat exchanger 25. Therefore, the temperature difference from the refrigerant passing through the second gas cooler 11 that merges at the merge point B can be reduced.
In addition, since the second flow rate adjustment valve 31 is installed in the branch pipe 23, the amount of refrigerant flowing through the branch pipe 23 is adjusted by adjusting the opening degree of the first flow rate adjustment valve 13 and the second flow rate adjustment valve 31. be able to.
In addition, it is preferable that the size of the 1st gas cooler 9 and the 2nd gas cooler 11 is determined by setting exit temperature of the 1st gas cooler 9 of a refrigerant | coolant so that it may become.

Since the refrigerant passing through the first gas cooler 9 exchanges heat with the water heated by the second gas cooler 11, the outlet portion of the first gas cooler 9 is in a state where the temperature of the water introduced into the second gas cooler 11 is low. The refrigerant temperature is relatively high. Thereby, since the temperature fall of the refrigerant | coolant injected is suppressed, it can prevent that the pressure becomes smaller than the pressure of the intermediate pressure part in the two-stage compressor 7. FIG.
Therefore, since the injection can be performed reliably, the intermediate pressure of the two-stage compressor 7 can be adjusted to some extent, and a decrease in the efficiency of the two-stage compressor 7 under conditions where the incoming water temperature is low can be avoided. . Even if the temperature of the water introduced into the second gas cooler 11 is lowered, the significant performance degradation of the two-stage compressor 7 can be suppressed, and an efficient operation can be performed over a wide range of conditions.

[Second Embodiment]
Next, the water heater 1 according to the second embodiment of the present invention will be described with reference to FIG. The water heater 1 according to the present embodiment is different from that of the first embodiment in the configuration of the injection circuit 21, so here, this different part will be mainly described, and the same part as that of the first embodiment described above will be duplicated. The description that was made is omitted.
In addition, the same code | symbol is attached | subjected to the same member as 1st embodiment.

FIG. 2 is a block diagram illustrating a circuit configuration of the water heater 1 according to the present embodiment.
In the present embodiment, a branching three-way valve (first valve member, first three-way valve) 39 is installed at the branch point A. The branch three-way valve 39 has two ports connected to the refrigerant pipe 19 and one port connected to the branch pipe 23. The branch three-way valve 39 is configured to be able to select communication of only the refrigerant pipe 19 and communication of both the refrigerant pipe 19 and the branch pipe 23 by switching the ports. In other words, the branch three-way valve 39 is configured to selectively flow the refrigerant to the branch pipe 23.

A main three-way valve (second valve member, second three-way valve) 41 is installed between the second gas cooler and the first flow rate adjustment valve. The main three-way valve 41 has two ports connected to the refrigerant pipe 19 and one port connected to the reflux pipe (first one-way pipe) 43.
The other end of the reflux pipe 43 communicates with the upstream side of the branch point of the injection pipe 29 in the branch pipe 23. A check valve 45 is installed in the reflux pipe 43 so that the refrigerant flows only from the main three-way valve 41 toward the branch pipe 23.
The main pipe three-way valve 41 is configured to be able to select communication of only the refrigerant pipe 19 and communication of both the refrigerant pipe 19 and the reflux pipe 43 by switching the ports. In other words, the main three-way valve 41 is configured to selectively flow the refrigerant to the reflux pipe 43.

Operation | movement of the water heater 1 concerning this embodiment comprised as mentioned above is demonstrated.
The refrigerant that has exited the first gas cooler 9 by switching the branch three-way valve 39 may or may not flow to the branch pipe 23. In addition, by switching the main three-way valve 41, a part of the refrigerant exiting the second gas cooler 11 can be supplied to the upstream side of the injection pipe 29 in the branch pipe 23 through the reflux pipe 43 or not.

For example, when the temperature of water introduced into the second gas cooler 11 is in a low state, the port of the branch three-way valve 39 is switched so that the refrigerant flows through the branch pipe 23, and a relatively high temperature refrigerant is supplied to the branch pipe 23. Supply. Since the operation of the water heater 1 in this state is the same as that of the water heater 1 of the first embodiment, a duplicate description is omitted here.
If it does in this way, since the temperature fall of the refrigerant | coolant injected is suppressed, it can prevent that the pressure becomes smaller than the pressure of the intermediate | middle pressure part in the two-stage compressor 7. FIG. Since injection can be performed in this manner, the intermediate pressure of the two-stage compressor 7 can be adjusted to some extent, and a decrease in the efficiency of the two-stage compressor 7 under conditions where the incoming water temperature is low can be avoided.
At this time, the refrigerant supplied to the branch pipe 23 by the check valve 45 does not flow into the reflux pipe 43.

Further, when the temperature of the water introduced into the second gas cooler 11 is normal or high, the port of the branch three-way valve 39 is switched so that the refrigerant does not flow into the branch pipe 23 and the port of the main three-way valve 41 is switched. Is switched so that the refrigerant flows through the reflux pipe 43.
A part of the refrigerant exiting the second gas cooler 11 is supplied from the main three-way valve 41 to the upstream side of the injection pipe 29 in the branch pipe 23 through the reflux pipe 43.
A part of the refrigerant passing through the branch pipe 23 is introduced into an injection pipe 29 branched from the upstream side of the double pipe heat exchanger 17 of the branch pipe 23. The refrigerant branched into the injection pipe 29 is expanded by the injection expansion valve 27, and when passing through the other pipe inside the double pipe heat exchanger 25, the refrigerant is heated by the refrigerant passing through one pipe and supplied to the injection port P. The

In this way, the refrigerant that has exited the second gas cooler 11 having a relatively low temperature is supplied to the injection pipe 29 as compared with the refrigerant that has exited the first gas cooler 9, so that Deterioration of performance (COP) can be suppressed.
In this way, even if the temperature of the water introduced into the second gas cooler 11 is lowered or raised, it is possible to suppress a significant performance degradation of the two-stage compressor 7 or a performance degradation of the refrigeration cycle 3, and to meet a wide range of conditions. Thus, efficient operation can be performed.

In the present embodiment, the branch three-way valve 39 and the main pipe three-way valve 41 configured as described above are used as the first valve member and the second valve member, but the present invention is not limited to this.
For example, the first valve member may be an on-off valve such as an electromagnetic valve that is installed upstream of the return pipe 43 in the branch pipe 23 and opens and closes the branch pipe 23. The second valve member may be an open / close valve such as an electromagnetic valve that opens and closes the return pipe 43 installed in the return pipe 43.

[Third embodiment]
Next, a water heater 1 according to a third embodiment of the present invention will be described with reference to FIG. The water heater 1 according to the present embodiment is different from that of the first embodiment in the configuration of the injection circuit 21, so here, this different part will be mainly described, and the same part as that of the first embodiment described above will be duplicated. The description that has been made will be omitted.
In addition, the same code | symbol is attached | subjected to the same member as 1st embodiment.

FIG. 3 is a block diagram illustrating a circuit configuration of the water heater 1 according to the present embodiment.
The injection circuit 21 of the present embodiment includes a branch pipe 47 branched from a branch point A located between the first gas cooler 9 and the second gas cooler 11 in the refrigerant pipe 19 and a branch expansion valve 49 installed in the branch pipe 47. A receiver 51 connected to the branch pipe 47 for gas-liquid separation, a liquid pipe 53 for supplying the liquid refrigerant separated by the receiver 51 to the junction B, and a gaseous refrigerant separated by the receiver 51 for injection. And an injection pipe 53 to be supplied to the port P.
A main expansion valve 57 is installed between the junction B and the air heat exchanger 15.

Operation | movement of the water heater 1 concerning this embodiment comprised as mentioned above is demonstrated.
Since the basic operations of the refrigeration cycle 3 and the water cycle 5 are the same as those of the first embodiment described above, the redundant description is omitted here, and the operation of the injection circuit 21 will be mainly described.
In the present embodiment, the main flow rate adjusting valve 13 mainly performs a flow rate adjusting function, and the refrigerant that has joined the liquid pipe 53 is decompressed by the main expansion valve 57 and is adiabatically expanded.

A part of the refrigerant exiting the first gas cooler 9 is introduced into the branch pipe 47. The refrigerant introduced into the branch pipe 47 is decompressed by the branch expansion valve 49, and a saturated liquid and a saturated gas are generated by the pressure and temperature. The saturated liquid and saturated gas are introduced into the receiver 51 and separated.
The gaseous refrigerant separated by the receiver 51 is introduced into the injection port P. On the other hand, the liquid refrigerant separated by the receiver 51 is supplied to the junction B. Thus, since the gaseous refrigerant separated by the receiver 51 is supplied to the injection port P of the two-stage compressor 7, the gaseous refrigerant can be reliably supplied to the injection port P.

Since the refrigerant passing through the first gas cooler 9 exchanges heat with the water heated by the second gas cooler 11, the outlet portion of the first gas cooler 9 is in a state where the temperature of the water introduced into the second gas cooler 11 is low. The refrigerant temperature is relatively high. Thereby, since the temperature fall of the refrigerant | coolant injected is suppressed, it can prevent that the pressure becomes smaller than the pressure of the intermediate pressure part in the two-stage compressor 7. FIG.
Therefore, since the injection can be performed reliably, the intermediate pressure of the two-stage compressor 7 can be adjusted to some extent, and a decrease in the efficiency of the two-stage compressor 7 under a condition where the incoming water temperature is low can be avoided. Even if the temperature of the water introduced into the second gas cooler 11 is lowered, the significant performance degradation of the two-stage compressor 7 can be suppressed, and an efficient operation can be performed over a wide range of conditions.

[Fourth embodiment]
Next, a water heater 1 according to a fourth embodiment of the present invention will be described with reference to FIG. Since the water heater 1 according to the present embodiment is different in the configuration of the injection circuit 21 from that of the third embodiment, this different part will be mainly described here, and the first embodiment and the third embodiment described above. A duplicate description of the same part is omitted.
In addition, the same code | symbol is attached | subjected to the same member as 1st embodiment and 3rd embodiment.

FIG. 4 is a block diagram illustrating a circuit configuration of the water heater 1 according to the present embodiment.
In the present embodiment, a branch three-way valve (third valve member, third three-way valve) 57 is installed at the branch point A. The branch three-way valve 57 has two ports connected to the refrigerant pipe 19 and one port connected to the branch pipe 47. The branch three-way valve 57 is configured to be able to select communication of only the refrigerant pipe 19 by switching ports and communication of both the refrigerant pipe 19 and the branch pipe 47. In other words, the branch three-way valve 57 is configured to selectively flow the refrigerant to the branch pipe 47.

A main three-way valve (fourth valve member, fourth three-way valve) 59 is installed between the second gas cooler 11 and the first flow rate adjusting valve 13. The main three-way valve 59 has two ports connected to the refrigerant pipe 19 and one port connected to the reflux pipe (second one-way pipe) 61.
The other end of the reflux pipe 61 communicates with the upstream side of the branch expansion valve 49 in the branch pipe 47. A check valve 63 is installed in the reflux pipe 61 so that the refrigerant flows only from the main three-way valve 59 toward the branch pipe 47.
The main pipe three-way valve 59 is configured to be able to select communication of only the refrigerant pipe 19 and communication of both the refrigerant pipe 19 and the reflux pipe 61 by switching ports. In other words, the main three-way valve 59 is configured to selectively flow the refrigerant to the reflux pipe 61.

Operation | movement of the water heater 1 concerning this embodiment comprised as mentioned above is demonstrated.
The refrigerant that has exited the first gas cooler 9 by switching the branch three-way valve 57 may or may not flow to the branch pipe 47. In addition, by switching the main three-way valve 59, a part of the refrigerant exiting the second gas cooler 11 can be supplied to the upstream side of the branch expansion valve 49 in the branch pipe 47 through the reflux pipe 61 or not. .

For example, when the temperature of the water introduced into the second gas cooler 11 is low, the port of the branch three-way valve 57 is switched so that the refrigerant flows through the branch pipe 47, and a relatively high-temperature refrigerant is supplied to the branch pipe 47. Supply. Since the operation of the water heater 1 in this state is the same as that of the water heater 1 of the first embodiment and the third embodiment, a duplicate description is omitted here.
If it does in this way, since the temperature fall of the refrigerant | coolant injected is suppressed, it can prevent that the pressure becomes smaller than the pressure of the intermediate | middle pressure part in the two-stage compressor 7. FIG. Since injection can be performed in this manner, the intermediate pressure of the two-stage compressor 7 can be adjusted to some extent, and a decrease in the efficiency of the two-stage compressor 7 under conditions where the incoming water temperature is low can be avoided.
At this time, the refrigerant supplied to the branch pipe 47 by the check valve 63 does not flow into the reflux pipe 61.

Further, when the temperature of the water introduced into the second gas cooler 11 is normal or high, the port of the branch three-way valve 47 is switched so that the refrigerant does not flow into the branch pipe 47 and the port of the main three-way valve 59 is switched. Is switched so that the refrigerant flows through the reflux pipe 61.
A part of the refrigerant exiting the second gas cooler 11 is supplied from the main three-way valve 59 to the upstream side of the branch expansion valve 49 in the branch pipe 47 through the reflux pipe 61.
The refrigerant introduced into the branch pipe 47 is decompressed by the branch expansion valve 49, and a saturated liquid and a saturated gas are generated by the pressure and temperature. The saturated liquid and saturated gas are introduced into the receiver 51 and separated.
The gaseous refrigerant separated by the receiver 51 is introduced into the injection port P. On the other hand, the liquid refrigerant separated by the receiver 51 is supplied to the junction B. Thus, since the gaseous refrigerant separated by the receiver 51 is supplied to the injection port P of the two-stage compressor 7, the gaseous refrigerant can be reliably supplied to the injection port P.

In this way, since the refrigerant that has exited the first gas cooler 9 is supplied to the injection pipe 55 as compared to the refrigerant that has exited the first gas cooler 9, the refrigerant that has exited the relatively cool second gas cooler 11 is supplied to the injection pipe 55. Deterioration of performance (COP) can be suppressed.
In this way, even if the temperature of the water introduced into the second gas cooler 11 is lowered or raised, it is possible to suppress a significant performance degradation of the two-stage compressor 7 or a performance degradation of the refrigeration cycle 3, and to meet a wide range of conditions. Thus, efficient operation can be performed.

In the present embodiment, the branch three-way valve 57 and the main pipe three-way valve 59 configured as described above are used as the third valve member and the fourth valve member, but the present invention is not limited to this.
For example, the third valve member may be an on-off valve such as an electromagnetic valve that is installed upstream of the return pipe 61 in the branch pipe 47 and opens and closes the branch pipe 47. The fourth valve member may be an open / close valve such as an electromagnetic valve that is installed in the return pipe 61 and opens and closes the return pipe 61.

The present invention is not limited to the embodiments described above, and various modifications may be made without departing from the spirit of the present invention.
For example, although carbon dioxide is used as the refrigerant in each embodiment, the invention is not limited to this, and a known refrigerant such as an alternative chlorofluorocarbon such as an HFC refrigerant can be used.

DESCRIPTION OF SYMBOLS 1 Water heater 3 Refrigeration cycle 5 Water cycle 7 Two-stage compressor 9 1st gas cooler 11 2nd gas cooler 13 1st flow control valve 15 Air heat exchanger 19 Refrigerant piping 21 Injection circuit 23 Branch piping 25 Double pipe heat exchanger 27 Injection expansion valve 29 Injection pipe 31 Second flow rate adjustment valve 37 Water pipe 39 Branch three-way valve 41 Main pipe three-way valve 43 Return pipe 47 Branch pipe 49 Branch expansion valve 51 Receiver 57 Branch three-way valve 59 Main three-way valve 61 Return pipe A Branch Point B Junction point P Injection port

Claims (4)

A two-stage compressor having an injection port between a low stage and a high stage, a first radiator, a second radiator, a main flow rate adjusting valve, and an evaporator are connected so that the refrigerant sequentially flows through the refrigerant pipe. A refrigeration cycle;
A water cycle having water piping through which water flows from the second radiator through the first radiator and heat exchanged between the first radiator and the refrigerant flowing through the second radiator;
A branch pipe connecting the confluence between the first radiator and the branch point between the second radiator the main flow control valve and the evaporator in the refrigerant pipe, the refrigerant from the branch pipe to the injection port An injection circuit having an injection pipe for supplying
A first valve member for selectively flowing the refrigerant to the branch pipe;
A first one-way pipe that is branched from between the second radiator and the main flow rate regulating valve, and that can supply the refrigerant only toward the upstream side of the injection pipe in the branch pipe;
A second valve member for selectively flowing the refrigerant to the first one-way pipe;
A water heater characterized by being provided with. The branch pipe, through one tube section and the branch flow adjusting valve of the double pipe heat exchanger and connecting the joining point and the branch point,
The injection pipe branches from the upstream side of the double pipe heat exchanger of the branch pipes, is connected through the interior other tube of the injection expansion valve and the double pipe heat exchanger to said injection port Turkey The water heater according to claim 1, wherein: Wherein the injection circuit, the previous SL min岐配pipe branch expansion valve, a receiver for separating gas and liquid, is provided, the refrigerant liquid separated by said receiver is introduced into the confluence, separated by the receiver The hot water heater according to claim 1, wherein the gaseous refrigerant is introduced into the injection port. It said first valve member is a three-way valve installed in the branch point,
Said second valve member, one of claims 1, wherein a three-way valve disposed between the second radiator in the refrigerant pipe and the main pipe flow regulating valve according to claim 3 The water heater described in item 1 .

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