阅读说明：本技术 板式热交换器以及热泵装置 (Plate heat exchanger and heat pump device ) 是由 南迫博和 于 2019-10-04 设计创作，主要内容包括：该板式热交换器具备：多个传热板,它们分别设置有沿一个方向贯通的第一贯通孔、第二贯通孔、第三贯通孔以及第四贯通孔,并且在一个方向上重叠来划分第一流路和第二流路；和一对端板,它们设置有与第一贯通孔相连且向第一流路导入第一流体的第一导入口、与第二贯通孔相连且从第一流路导出第一流体的第一导出口、以及与第三贯通孔相连且向第二流路导入第二流体的第二导入口、与第四贯通孔相连且从第二流路导出第二流体的第二导出口、以及与第二贯通孔相连并从第一流路分支的连接口,在一个方向上夹住多个传热板,所述连接口与和该板式热交换器分开设置的泄压阀连接。(The plate heat exchanger includes: a plurality of heat transfer plates that are provided with a first through hole, a second through hole, a third through hole, and a fourth through hole that penetrate in one direction, and that overlap in one direction to define a first channel and a second channel; and a pair of end plates provided with a first inlet port connected to the first through hole and introducing the first fluid into the first flow path, a first outlet port connected to the second through hole and discharging the first fluid from the first flow path, a second inlet port connected to the third through hole and introducing the second fluid into the second flow path, a second outlet port connected to the fourth through hole and discharging the second fluid from the second flow path, and a connection port connected to the second through hole and branched from the first flow path, the plurality of heat transfer plates being sandwiched in one direction, and the connection port being connected to a relief valve provided separately from the plate heat exchanger.)

1. A plate heat exchanger is characterized by comprising:

a plurality of heat transfer plates that are provided with a first through-hole, a second through-hole, a third through-hole, and a fourth through-hole that penetrate in one direction, respectively, that overlap in the one direction, that divide a first channel through which a first fluid flows and a second channel through which a second fluid flows, and that exchange heat between the first fluid in the first channel and the second fluid in the second channel; and

a pair of end plates provided with: a first introduction port that is connected to the first through-hole and introduces the first fluid into the first flow path, a first discharge port that is connected to the second through-hole and introduces the first fluid from the first flow path, a second introduction port that is connected to the third through-hole and introduces the second fluid into the second flow path, a second discharge port that is connected to the fourth through-hole and introduces the second fluid from the second flow path, and a connection port that is connected to either one of the first through-hole and the second through-hole and branches from the first flow path, and the plurality of heat transfer plates are sandwiched in the one direction,

the connection port is connected to a pressure relief valve provided separately from the plate heat exchanger.

2. A plate heat exchanger according to claim 1,

the plate heat exchanger is provided with a temperature sensor that detects a temperature of the first fluid flowing through the plate heat exchanger.

3. A plate heat exchanger according to claim 2,

the temperature sensor is installed on an end plate provided with the connecting port.

4. A plate heat exchanger according to claim 3,

at least one of the first introduction port, the first discharge port, the second introduction port, and the second discharge port is provided in an end plate provided with the connection port,

the distance between the connection port and the temperature sensor is smaller than the distance between the first introduction port, the first outlet port, the second introduction port, or the second outlet port, which is provided in the end plate provided with the connection port, and the temperature sensor, respectively.

5. A plate heat exchanger according to claim 3 or 4,

the temperature sensor is provided between the connection port and an end portion of the end plate when viewed from a direction perpendicular to a surface of the end plate on which the connection port is provided, and the first introduction port, the first discharge port, the second introduction port, and the second discharge port are not provided between the connection port and the end portion of the end plate.

6. A plate heat exchanger according to claim 2,

the temperature sensor is mounted to the heat transfer plate located on a side surface of the plate heat exchanger.

7. A plate heat exchanger according to claim 6,

the distance between the connection port and the temperature sensor is smaller than the distance between the first introduction port and the temperature sensor, the distance between the first discharge port and the temperature sensor, the distance between the second introduction port and the temperature sensor, and the distance between the second discharge port and the temperature sensor.

8. A plate heat exchanger according to any of claims 1-7,

the flow path cross-sectional area of the connection port is larger than the flow path cross-sectional area of the first lead-out port.

9. A heat pump device is characterized by comprising:

a refrigerant circuit in which a compressor, a plate heat exchanger, an expansion mechanism, and a heat source side heat exchanger are connected via refrigerant pipes, and in which a refrigerant circulates;

a heat medium circuit in which a pump, the plate heat exchanger, and a use-side heat exchanger are connected via heat medium pipes, and in which a heat medium circulates; and

and a relief valve connected to a connection port branched from the heat medium circuit in the plate heat exchanger and provided separately from the plate heat exchanger.

10. The heat pump apparatus according to claim 9,

the plate heat exchanger has:

a plurality of heat transfer plates that are provided with a first through hole, a second through hole, a third through hole, and a fourth through hole that penetrate in one direction, respectively, and that overlap in the one direction, and that divide a first flow path through which the heat medium flows and a second flow path through which the refrigerant flows, and that cause the heat medium in the first flow path to exchange heat with the refrigerant in the second flow path; and

a pair of end plates provided with: a first introduction port that is connected to the first through hole and introduces the heat medium from the heat medium pipe into the first flow path, a first discharge port that is connected to the second through hole and introduces the heat medium from the first flow path to the heat medium pipe, a second introduction port that is connected to the third through hole and introduces the refrigerant from the refrigerant pipe into the second flow path, a second discharge port that is connected to the fourth through hole and introduces the refrigerant from the second flow path to the refrigerant pipe, the connection port that is connected to the first through hole and is disposed at a position facing the first introduction port or the second through hole and is disposed at a position facing the first discharge port, and the plurality of heat transfer plates are sandwiched in the one direction.

11. The heat pump device according to claim 9 or 10, comprising:

a temperature sensor that detects a temperature associated with the heat medium flowing in the plate heat exchanger; and

a control device communicatively connected to the temperature sensor and the compressor,

the control device stops the compressor when the temperature detected by the temperature sensor is lower than a preset threshold value.

12. The heat pump apparatus according to any one of claims 9 to 11,

the relief valve is opened when the pressure of the heat medium circuit exceeds a preset set value, and is closed when the pressure of the heat medium circuit is equal to or less than the set value after the relief valve is opened.

13. The heat pump apparatus according to any one of claims 9 to 12,

the pressure release valve is arranged outdoors.

14. The heat pump apparatus according to any one of claims 9 to 12,

a release pipe for releasing the fluid discharged from the relief valve to the outside is connected to the relief valve.

15. The heat pump apparatus according to any one of claims 9 to 14,

in the heat medium circuit, a check valve is provided between the pump and the plate heat exchanger.

Technical Field

The present invention relates to a plate heat exchanger and a heat pump device.

Background

Conventionally, as a heat pump device using a heat pump cycle, a heat pump device that heats water to supply hot water and performs air conditioning is known. In such a heat pump device, heat exchange between the refrigerant circulating in the refrigerant circuit and water flowing through the water circuit is performed in a plate-type water-refrigerant heat exchanger, and the water in the water circuit is heated. Here, since the water may expand by heating, a relief valve may be provided in the water circuit (see, for example, patent document 1).

Patent document 1: japanese patent No. 5246041 (paragraph 0017, FIG. 2)

When the water circuit (first flow path, heat medium circuit) and the refrigerant circuit (second flow path) communicate with each other due to damage to the water refrigerant heat exchanger (plate heat exchanger), the refrigerant (second fluid) having a higher pressure than the water (first fluid, heat medium) leaks into the water circuit. In general, when the refrigerant leaks into the water circuit, the pressure of the water circuit rises, and therefore, a relief valve of the water circuit is opened to protect components and pipes of the water circuit, and water and the refrigerant are discharged from the relief valve. At this time, the pressure of the refrigerant leaking to the water circuit becomes the same as the pressure of the water circuit, and the pressure of the water circuit becomes the set pressure of the relief valve. Here, depending on the set pressure of the relief valve, the temperature of the refrigerant flowing into the water circuit and adiabatically expanded may be lower than the freezing point of water. In this case, the refrigerant of a temperature lower than the freezing point of water is mixed with water, whereby the water becomes ice. Further, the pressure of the refrigerant is decreased, and the refrigerant receives heat from water, so that the refrigerant is vaporized. As a result, the fluid in which the fine ice is mixed with the refrigerant gas is discharged from the relief valve. Since this state continues, ice gradually adheres to the flow path in the relief valve, and the relief valve may be closed, and water and the refrigerant may not be discharged from the relief valve.

Disclosure of Invention

The present invention has been made in view of the above circumstances, and an object thereof is to provide a plate heat exchanger and a heat pump device that can prevent a relief valve from being closed and can more reliably discharge a second fluid that has leaked to a first flow path from the first flow path through the relief valve.

According to a first aspect of the present invention, a plate heat exchanger includes: a plurality of heat transfer plates that are provided with a first through-hole, a second through-hole, a third through-hole, and a fourth through-hole that penetrate in one direction, respectively, that overlap in one direction, that divide a first flow path through which a first fluid flows and a second flow path through which a second fluid flows, and that exchange heat between the first fluid in the first flow path and the second fluid in the second flow path; and a pair of end plates provided with: the first inlet port connected to the first through hole and configured to introduce the first fluid into the first flow path, the first outlet port connected to the second through hole and configured to discharge the first fluid from the first flow path, the second inlet port connected to the third through hole and configured to introduce the second fluid into the second flow path, the second outlet port connected to the fourth through hole and configured to discharge the second fluid from the second flow path, and the connection port connected to either one of the first through hole and the second through hole and branched from the first flow path, and the connection port is connected to a relief valve provided separately from the plate heat exchanger, with the plurality of heat transfer plates interposed therebetween in one direction.

According to a second aspect of the present invention, a heat pump device includes: a refrigerant circuit in which a compressor, a plate heat exchanger, an expansion mechanism, and a heat source side heat exchanger are connected via refrigerant pipes, and in which a refrigerant circulates; a heat medium circuit in which a pump, a plate heat exchanger, and a use-side heat exchanger are connected via heat medium pipes, and in which a heat medium circulates; and a relief valve connected to a connection port branched from the heat medium circuit in the plate heat exchanger and provided separately from the plate heat exchanger.

According to the plate heat exchanger described above, when the plate heat exchanger is damaged and the first channel and the second channel communicate with each other, the second fluid leaks into the first channel, whereby the pressure in the first channel increases, and the relief valve opens. The relief valve is connected to a connection port branched from the first flow path, separately from a first introduction port for introducing the first fluid into the first flow path and a first discharge port for discharging the first fluid from the first flow path. Therefore, the second fluid leaking to the first flow path is not mixed with the first fluid but is collectively discharged from the relief valve. Therefore, since the relief valve can be prevented from being closed by the solidification of the first fluid, the second fluid leaking to the first flow path can be more reliably discharged from the first flow path through the relief valve.

Further, according to the heat pump device described above, when the plate heat exchanger is damaged and the refrigerant circuit and the heat medium circuit communicate with each other, the refrigerant leaks into the heat medium circuit, whereby the pressure in the heat medium circuit increases, and the relief valve opens. Since the relief valve is connected to a connection port provided in a branch of the heat medium circuit in the plate heat exchanger, the refrigerant leaking to the heat medium circuit is not substantially mixed with the heat medium, and is collectively discharged from the relief valve. Therefore, the relief valve can be prevented from being closed by the solidification of the heat medium, and the refrigerant leaking into the heat medium circuit can be more reliably discharged from the heat medium circuit through the relief valve.

Drawings

Fig. 1 is a diagram showing a schematic configuration of a heat pump device according to embodiment 1 of the present invention.

Fig. 2 is an exploded perspective view schematically showing a plate heat exchanger according to embodiment 1 of the present invention.

Fig. 3 is a front view schematically showing the plate heat exchanger.

Fig. 4 is a cross-sectional view taken along line IV-IV of fig. 3.

Fig. 5 is a view schematically showing the flow of fluid in the plate heat exchanger.

Fig. 6 is a view schematically showing the flow of fluid in the plate heat exchanger in the case of refrigerant leakage.

Fig. 7 is a diagram showing a schematic configuration of a heat pump device according to embodiment 2 of the present invention.

Fig. 8 is a sectional view taken along line IV-IV of fig. 3 with the relief valve installed.

Fig. 9 is a front view schematically showing a plate heat exchanger according to embodiment 4 of the present invention.

Fig. 10 is a cross-sectional view taken along line X-X of fig. 9.

Fig. 11 is a cross-sectional view taken along line X-X in fig. 9 of a plate heat exchanger according to a modification of embodiment 4.

Detailed Description

(embodiment mode 1)

Embodiment 1 of the present invention will be described below with reference to fig. 1 to 6. The same or corresponding portions are denoted by the same reference numerals in the drawings.

Fig. 1 is a diagram showing a schematic configuration of a heat pump device 1 according to the present embodiment. As shown in fig. 1, the heat pump apparatus 1 includes: a refrigerant circuit 10 that circulates a refrigerant, a water circuit (heat medium circuit) 20 that circulates water (heat medium), and a relief valve 30.

The refrigerant circuit 10 has a structure in which a compressor 12, a plate heat exchanger 40, an expansion valve (expansion mechanism) 13, and an air heat exchanger (heat source side heat exchanger) 14 are connected via a refrigerant pipe 11.

As the refrigerant circulating through the refrigerant circuit 10, a refrigerant having properties of low Ozone depletion Potential (hereinafter referred to as "ODP") and low Global Warming Potential (hereinafter referred to as "GWP") is used in consideration of the load on the environment. Specifically, HFO (hydrofluoroolefin) refrigerants such as R32, HFO-1234yf, and HFO-1234ze, which have a GWP lower than that of R410A or R407C, and HC (hydrocarbon) refrigerants such as propane and butane, are used as such refrigerants. The above-mentioned refrigerants have low ODP and low GWP properties, but also have flammability. The refrigerant may be used as a single refrigerant, or may be used as a mixed refrigerant in which two or more kinds are mixed.

The compressor 12 compresses a low-pressure refrigerant sucked thereinto and discharges the compressed refrigerant as a high-pressure refrigerant. In the present embodiment, the compressor 12 is provided with an inverter device or the like, and the capacity (the amount of refrigerant sent per unit time) of the compressor 12 can be changed by arbitrarily changing the drive frequency.

The plate heat exchanger 40 performs heat exchange between the refrigerant flowing through the refrigerant circuit 10 and the water flowing through the water circuit 20. The detailed structure of the plate heat exchanger 40 will be described later.

The expansion valve 13 adjusts the flow rate of the refrigerant, for example, adjusts the pressure (reduces the pressure) of the refrigerant flowing into the air heat exchanger 14. In the present embodiment, an electronic expansion valve capable of changing the opening degree based on an instruction from a control device not shown is used as the expansion valve 13.

The air heat exchanger 14 exchanges heat between the refrigerant flowing through the refrigerant circuit 10 and air (outside air) blown by a fan. In the present embodiment, the air heat exchanger 14 is a fin-tube heat exchanger made of copper, aluminum, or the like, for example.

In the present embodiment, the heat pump device 1 is configured to be able to perform a normal operation in which the refrigerant circuit 10 heats water flowing through the water circuit 20, and a defrosting operation in which the refrigerant flows in the opposite direction to the normal operation to defrost the air heat exchanger 14. When the normal operation is performed in an environment where the outside air is at a low temperature, the water condensed in the air heat exchanger 14 may freeze and frost may adhere to the surface of the air heat exchanger 14. This frost grows as the normal operation continues, and decreases the heat exchange efficiency of the air heat exchanger 14. Therefore, the defrosting operation is required in a low-temperature environment.

Specifically, the four-way valve 15 is provided in the refrigerant circuit 10 so as to enable the normal operation and the defrosting operation. The four-way valve 15 functions as a flow path switching device that switches the flow direction of the refrigerant in the refrigerant circuit 10 between the normal operation and the defrosting operation. The plate heat exchanger 40 functions as a radiator (condenser) that heats water flowing through the water circuit 20 during the normal operation, and functions as a heat absorber (evaporator) that absorbs heat from the water in the water circuit 20 during the defrosting operation. The air heat exchanger 14 functions as a heat absorber (evaporator) during the normal operation and functions as a radiator (condenser) during the defrosting operation.

In the present embodiment, the heat pump device 1 is provided with an outdoor unit 51 that houses the compressor 12, the four-way valve 15, the plate heat exchanger 40, the expansion valve 13, and the air heat exchanger 14 of the refrigerant circuit 10. The outdoor unit 51 is installed outdoors. The outdoor unit 51 is provided with a control device, not shown, which controls the operation of the refrigerant circuit 10. The control device controls, for example, driving of the compressor 12, switching of the flow path of the four-way valve 15, opening degree of the expansion valve 13, and blowing of the fan of the air heat exchanger 14.

Next, an example of the operation of the refrigerant circuit 10 will be described with reference to fig. 1. In fig. 1, the flow direction of the refrigerant during the normal operation in the refrigerant circuit 10 is shown by solid arrows, and the flow direction of the refrigerant during the defrosting operation is shown by broken arrows.

During a normal operation, the four-way valve 15 switches the flow path of the refrigerant as indicated by the solid line, and the refrigerant circuit 10 is configured such that the high-temperature and high-pressure refrigerant flows into the plate heat exchanger 40. That is, during the normal operation, the refrigerant circulates through the refrigerant circuit 10 in the order of the compressor 12, the four-way valve 15, the plate heat exchanger 40, the expansion valve 13, the air heat exchanger 14, the four-way valve 15, and the compressor 12.

The high-temperature high-pressure gas refrigerant (hereinafter referred to as "gas refrigerant") discharged from the compressor 12 flows into the refrigerant flow path (second flow path) of the plate heat exchanger 40 through the four-way valve 15. In the plate heat exchanger 40, heat exchange is performed between the refrigerant flowing through the refrigerant flow path and the water flowing through the water flow path (first flow path) of the plate heat exchanger 40, and the heat of condensation of the refrigerant is dissipated to the water. Thereby, the refrigerant flowing into the plate heat exchanger 40 condenses into a high-pressure liquid refrigerant (hereinafter, referred to as a "liquid refrigerant"). The water flowing through the water flow path of the plate heat exchanger 40 is heated by heat radiated from the refrigerant.

The high-pressure liquid refrigerant condensed in the plate heat exchanger 40 flows into the expansion valve 13, and is decompressed to become a low-pressure two-phase refrigerant (hereinafter, referred to as a "two-phase refrigerant"). The low-pressure two-phase refrigerant flows into the air heat exchanger 14. The air heat exchanger 14 performs heat exchange between the refrigerant flowing through the inside thereof and air (outside air) blown by the fan. As a result, the refrigerant flowing into the air heat exchanger 14 absorbs heat from the air and evaporates, becoming a low-pressure gas refrigerant. The low-pressure gas refrigerant is sucked into the compressor 12 through the four-way valve 15. The refrigerant sucked into the compressor 12 is compressed into a high-temperature high-pressure gas refrigerant. In the normal operation, the above cycle is repeated.

During the defrosting operation, the refrigerant circuit 10 is configured such that the flow path of the refrigerant is switched by the four-way valve 15 as indicated by the broken line, and the high-temperature and high-pressure refrigerant flows into the air heat exchanger 14. That is, during the defrosting operation, the refrigerant circulates through the refrigerant circuit 10 in the order of the compressor 12, the four-way valve 15, the air heat exchanger 14, the expansion valve 13, the plate heat exchanger 40, the four-way valve 15, and the compressor 12.

The high-temperature and high-pressure gas refrigerant discharged from the compressor 12 flows into the air heat exchanger 14 through the four-way valve 15. The refrigerant flows through the air heat exchanger 14, and frost adhering to the surface of the air heat exchanger 14 is heated and melted by the heat of condensation of the refrigerant. The refrigerant flowing into the air heat exchanger 14 condenses into a high-pressure liquid refrigerant. The liquid refrigerant flowing out of the air heat exchanger 14 flows into the expansion valve 13, becomes a two-phase refrigerant, and flows into the plate heat exchanger 40. The two-phase refrigerant flowing into the plate heat exchanger 40 absorbs heat from the water flowing through the water flow path in the plate heat exchanger 40 and evaporates, thereby becoming a gas refrigerant. The gas refrigerant is sucked into the compressor 12 through the four-way valve 15, and is compressed into a high-temperature and high-pressure gas refrigerant. In the defrosting operation, the above cycle is repeated.

The water circuit 20 has a structure in which a pump 22, the plate heat exchanger 40, and a heating terminal (use side heat exchanger) 23 are connected to each other through a water pipe (heat medium pipe) 21. The water circulating through the water circuit 20 is, for example, pure water or tap water.

The pump 22 is a device that applies pressure to the water in the water circuit 20 to circulate the water in the water circuit 20. The heating terminal 23 is installed indoors (indoors) to warm a space 60 to be air-conditioned. In the present embodiment, the heating terminal 23 is, for example, a plate heater, a floor heating plate, or the like, and has a heat exchange unit therein. The water in the water circuit 20 heated in the plate heat exchanger 40 flows into the heat exchange portion. The heat exchange between the water flowing into the heat exchange portion of the heating terminal 23 and the air in the space 60 is performed, and the heat is radiated from the water to the air in the space 60. Thereby warming the space 60 and cooling the water.

In the present embodiment, the water circuit 20 is further provided with an expansion tank 24 and a relief valve 25. The expansion tank 24 is a device for controlling the pressure, which varies with the volume change of the water in the water circuit 20 due to heating or the like, within a certain range. The expansion tank 24 is connected to a pipe branched from the water pipe 21 connecting the pump 22 and the heating terminal 23. The safety valve 25 is provided as a protection device. The relief valve 25 releases the water in the water circuit 20 to the outside when the pressure of the water circuit 20 rises beyond the pressure control range of the expansion tank 24. The safety valve 25 is connected to a pipe branching from the water pipe 21 connecting the plate heat exchanger 40 and the heating terminal 23.

In the present embodiment, the heat pump device 1 is provided with an indoor unit 52 that houses the pump 22, the expansion tank 24, and the relief valve 25 of the water circuit 20. The indoor unit 52 is installed indoors (indoors). The indoor unit 52 is provided with a control device, not shown, that controls the operation of the water circuit 20 such as driving of the pump 22.

The pressure relief valve 30 is connected to the plate heat exchanger 40. More specifically, the relief valve 30 is connected to a connection port 48 of the plate heat exchanger 40 described later. The connection port 48 is branched from the water circuit 20 in the plate heat exchanger 40. In the present embodiment, the relief valve 30 is housed in the outdoor unit 51 together with the plate heat exchanger 40, and is disposed outdoors. The relief valve 30 automatically opens to release fluid such as water or refrigerant to the outside when the pressure of the water circuit 20 exceeds a preset set value due to leakage of refrigerant from the refrigerant circuit 10 to the water circuit 20 in the plate heat exchanger 40, for example. When the pressure of the water circuit 20 becomes equal to or lower than the set value due to the release of the fluid, the relief valve 30 automatically closes to stop the release of the fluid.

Next, the structure of the plate heat exchanger 40 will be described with reference to fig. 2 to 6. Fig. 2 is an exploded perspective view schematically showing the plate heat exchanger 40. Fig. 3 is a front view schematically showing the plate heat exchanger 40. Fig. 4 is a cross-sectional view taken along line IV-IV of fig. 3.

As shown in fig. 2 and 4, the plate heat exchanger 40 includes a plurality of heat transfer plates 41 and a pair of end plates 43A and 43B.

The plurality of heat transfer plates 41 are stacked in a predetermined one direction (hereinafter referred to as a "stacking direction"), and are configured to divide a water flow path (first flow path) through which water (heat medium, first fluid) flows and a refrigerant flow path (second flow path) through which a refrigerant (second fluid) flows, and exchange heat between the water in the water flow path and the refrigerant in the refrigerant flow path. Each heat transfer plate 41 is provided with a first through hole 42A, a second through hole 42B, a third through hole 42C, and a fourth through hole 42D, which are four through holes penetrating in the stacking direction. In the present embodiment, the heat transfer plate 41 is formed in a substantially rectangular plate shape when viewed from the stacking direction, and a first through hole 42A, a second through hole 42B, a third through hole 42C, and a fourth through hole 42D are provided at four corners of the substantially rectangular shape, respectively. A plurality of rows of corrugated heat transfer surfaces for heat exchange, which are displaced in the stacking direction, are formed in a V shape, for example, on the surface of the heat transfer plate 41. The heat transfer plate 41 is manufactured by press working a metal plate such as a stainless steel plate.

The pair of end plates 43A, 43B sandwich the plurality of heat transfer plates 41 in the stacking direction. The pair of end plates 43A and 43B are provided with a first introduction port 44, a first discharge port 45, a second introduction port 46, a second discharge port 47, and a connection port 48. The first inlet 44 is connected to the first through hole 42A of the heat transfer plate 41 and introduces water from the water pipe 21 to the water channel. The first outlet port 45 is connected to the second through hole 42B of the heat transfer plate 41, and is used for leading water from the water flow path to the water pipe 21. The second introduction port 46 is connected to the third through hole 42C of the heat transfer plate 41, and introduces the refrigerant from the refrigerant pipe 11 into the refrigerant flow path. The second lead-out port 47 is connected to the fourth through hole 42D of the heat transfer plate 41, and leads out the refrigerant from the refrigerant flow path to the refrigerant pipe 11. The relief valve 30 is connected to the connection port 48. The connection port 48 is connected to the second through hole 42B of the heat transfer plate 41 and branched from the water channel. In the present embodiment, the connection port 48 is connected to the second through hole 42B of the heat transfer plate 41 and is disposed at a position facing the first lead-out port 45. In the above description, for the sake of easy explanation, the flows of the refrigerant and water are described with reference to the normal operation. Therefore, for example, during the defrosting operation, the refrigerant is introduced from the second lead-out port 47 into the plate heat exchanger 40 and is led out from the second lead-in port 46.

In the present embodiment, as shown in fig. 2 to 4, the pair of end plates 43A, 43B are formed in a substantially rectangular plate shape when viewed from the stacking direction. In the end plate 43A, the second introduction port 46, the second discharge port 47, and the connection port 48 are provided at three corners corresponding to the positions of the third through hole 42C, the fourth through hole 42D, and the second through hole 42B of the heat transfer plate 41, among the four corners of the substantially rectangular shape. In the end plate 43B, the first introduction port 44 and the first discharge port 45 are provided at two corners corresponding to the positions of the first through hole 42A and the second through hole 42B of the heat transfer plate 41, among the four corners of the substantially rectangular shape. Therefore, the connection port 48 is provided in an end plate different from the first introduction port 44 and the first discharge port 45. Further, cylindrical nozzles are provided in the first inlet 44, the first outlet 45, the second inlet 46, the second outlet 47, and the connection port 48, respectively.

The plurality of heat transfer plates 41 and the pair of end plates 43A and 43B are overlapped with each other so that their outer peripheral edges overlap each other, and are joined by brazing or the like. Thereby, a water flow passage and a refrigerant flow passage are formed between the adjacent heat transfer plates 41. In a state where the plurality of heat transfer plates 41 are stacked, the water flow path and the refrigerant flow path are alternately arranged, the first through hole 42A and the second through hole 42B communicate with the water flow path, and the third through hole 42C and the fourth through hole 42D communicate with the refrigerant flow path.

Fig. 5 is a diagram schematically showing the flow of fluid in the plate heat exchanger 40. In fig. 5, the flow of water in the plate heat exchanger 40 is shown by solid lines, and the flow of refrigerant is shown by broken lines. During normal operation, as shown in fig. 5, water in the water circuit 20 is introduced into the plate heat exchanger 40 through the first inlet port 44, flows through the water flow path formed between the heat transfer plates 41, and is discharged through the first outlet port 45. The refrigerant in the refrigerant circuit 10 is introduced into the plate heat exchanger 40 through the second introduction port 46, flows through the refrigerant flow paths formed between the heat transfer plates 41, and is discharged through the second discharge port 47. At this time, heat is exchanged between the water flowing through the water flow path and the refrigerant flowing through the refrigerant flow path.

Next, the operation in the case where the refrigerant leaks into the water flow path in the plate heat exchanger 40 will be described with reference to fig. 6. Fig. 6 is a diagram schematically showing the flow of fluid in the plate heat exchanger 40 when the refrigerant leaks. In the plate heat exchanger 40, for example, the heat transfer plate 41 may be damaged by metal fatigue fracture or the like due to corrosion or aging of the heat transfer plate 41. In addition, for example, in the defrosting operation, the refrigerant absorbs heat from water in the plate heat exchanger 40, and thus the water is cooled. At this time, when the water temperature is low, there is a possibility that water flowing through the water circuit of the plate heat exchanger 40 freezes. In this case, it is considered that the heat transfer plate 41 may be deformed or broken due to volume expansion when water freezes.

During normal operation, for example, the pressure of the water in the water circuit 20 is about 0.3MPa, and the pressure of the refrigerant in the refrigerant circuit 10 when the refrigerant flows into the plate heat exchanger 40 is about 1.0 MPa. Therefore, since the pressure of the refrigerant is higher than the pressure of water, when the heat transfer plates 41 are broken and the water flow path and the refrigerant flow path communicate with each other at the communication portion a as shown in fig. 6, the refrigerant flowing through the refrigerant flow path flows into the water flow path through the communication portion a. This increases the pressure in the water flow path. When the pressure of the water flow path exceeds a set value of the relief valve 30 connected to the connection port 48, the relief valve 30 opens.

The refrigerant flowing into the water flow path from the communication portion a flows toward the relief valve 30 while pushing the water existing between the communication portion a and the relief valve 30, and is discharged from the relief valve 30. After the discharge of the water is completed, the refrigerant is discharged from the relief valve 30. At this time, the refrigerant flowing into the water flow path from the communication portion a may flow into the water circuit 20 from the first introduction port 44 or the first discharge port 45. However, since water is incompressible, the flow of the refrigerant to the first introduction port 44 or the first discharge port 45 is inhibited by the water. Even if the relief valve 25 is opened and the water or the refrigerant can be released from the relief valve 25, the path from the communication portion a to the relief valve 25 through the first lead-out port 45 is much longer than the path from the communication portion a to the relief valve 30, and the pressure loss increases, so that the refrigerant is less likely to flow toward the relief valve 25. Therefore, after the relief valve 30 is opened, almost all of the refrigerant is discharged from the relief valve 30. On the other hand, since the connection port 48 to which the relief valve 30 is connected is provided separately from the first introduction port 44 and the first discharge port 45, the water in the water circuit 20 flowing into the water flow path can flow from the first introduction port 44 to the first discharge port 45 through the water flow path even after the relief valve 30 is opened. Further, since the pressure of the water is lower than the pressure of the refrigerant flowing toward the relief valve 30, the flow of the water to the relief valve 30 is hindered by the refrigerant. Therefore, when the relief valve 30 is opened, the water existing between the communication portion a and the relief valve 30 is discharged from the relief valve 30, and the other water is hardly discharged from the relief valve 30 and flows from the first lead-out port 45 to the water circuit 20. In this way, the refrigerant flowing into the water flow path from the communication portion a is not mixed with water but is collectively discharged from the relief valve 30.

As in the conventional configuration, for example, when a relief valve is provided in the water circuit downstream of the plate heat exchanger, the refrigerant flowing into the water flow path flows from the first lead-out port to the water pipe together with the water in the water flow path and then flows toward the relief valve, and therefore the refrigerant is discharged from the relief valve along with the water. Therefore, the refrigerant cools the water, so that the water turns into ice and gradually adheres to the flow path of the relief valve, thereby closing the relief valve. On the other hand, in the configuration of the present embodiment, as described above, the refrigerant flowing from the communication portion a into the water flow path is not substantially mixed with water, and is collectively discharged from the relief valve 30. Further, since the amount of water discharged from the relief valve 30 is small, even if the refrigerant flowing into the water flow path from the communication portion a adiabatically expands to a temperature lower than the freezing point of water, the relief valve 30 is not closed. Therefore, since the relief valve 30 can be prevented from being closed, the refrigerant leaked to the water flow path can be more reliably discharged from the water flow path through the relief valve 30.

The heat pump device 1 of the present embodiment includes: a refrigerant circuit 10 that circulates a refrigerant by connecting a compressor 12, a plate heat exchanger 40, an expansion valve 13, and an air heat exchanger 14 to each other via a refrigerant pipe 11; a water circuit 20 that circulates water by connecting a pump 22, a plate heat exchanger 40, and a heating terminal 23 via a water pipe 21; and a relief valve 30 connected to a connection port 48 branched from the water circuit 20 in the plate heat exchanger 40.

According to the above configuration, when the plate heat exchanger 40 is damaged and the refrigerant circuit 10 and the water circuit 20 communicate with each other, the refrigerant leaks into the water circuit 20, the pressure in the water circuit 20 increases, and the relief valve 30 opens. Since the relief valve 30 is connected to the connection port 48 branched from the water circuit 20 in the plate heat exchanger 40, the refrigerant leaked to the water circuit 20 is collectively discharged from the relief valve 30 without being mixed with water. Therefore, the relief valve 30 can be prevented from being closed by ice generated by the water being cooled by the refrigerant, and the refrigerant leaking to the water circuit 20 can be more reliably discharged from the water circuit 20 via the relief valve 30.

Further, the plate heat exchanger 40 of the present embodiment includes: a plurality of heat transfer plates 41 that are provided with a first through hole 42A, a second through hole 42B, a third through hole 42C, and a fourth through hole 42D, respectively, that penetrate in the stacking direction, that overlap in the stacking direction, and that divide a water flow path through which water flows and a refrigerant flow path through which a refrigerant flows, and that exchange heat between the water in the water flow path and the refrigerant in the refrigerant flow path; and a pair of end plates 43A, 43B provided with a first introduction port 44 connected to the first through hole 42A for introducing water into the water flow path, a first discharge port 45 connected to the second through hole 42B for discharging water from the water flow path, a second introduction port 46 connected to the third through hole 42C for introducing the refrigerant into the refrigerant flow path, a second discharge port 47 connected to the fourth through hole 42D for discharging the refrigerant from the refrigerant flow path, and a connection port 48 connected to the second through hole 42B and branched from the water flow path for connecting to the relief valve 30, and sandwiching the plurality of heat transfer plates 41 in the stacking direction.

According to the above configuration, when the plate heat exchanger 40 is damaged and the water flow path communicates with the refrigerant flow path, the refrigerant leaks into the water flow path, the pressure in the water flow path increases, and the relief valve 30 opens. The relief valve 30 is connected to a connection port 48 branched from the water flow path, separately from a first introduction port 44 for introducing water into the water flow path and a first discharge port 45 for discharging water from the water flow path. Therefore, the refrigerant leaking to the water flow path is not mixed with water at all, and is discharged from the relief valve 30 collectively. Therefore, the relief valve can be prevented from being closed by ice generated by cooling water with the refrigerant, and the refrigerant leaking to the water flow path can be more reliably discharged from the water flow path through the relief valve 30.

The relief valve 30 is disposed outdoors. Therefore, when the refrigerant is discharged from the relief valve 30, the refrigerant is released to the outside without flowing into the room where the heating terminal 23, the indoor unit 52, and the like are installed, and therefore the possibility of suffocation caused by the refrigerant gas in the room can be reduced. Further, when the refrigerant is flammable, the refrigerant does not flow into the room, and therefore the possibility of burning of the refrigerant gas in the room can be reduced. Therefore, the safety in the room can be improved.

In the present embodiment, the connection port 48 is connected to the second through hole 42B of the heat transfer plate 41 and is disposed at a position facing the first lead-out port 45, but the present invention is not limited thereto. The connection port 48 may be connected to the first through hole 42A and disposed at a position facing the first introduction port 44. The end plate 43A is provided with the second introduction port 46, the second discharge port 47, and the connection port 48, and the end plate 43B is provided with the first introduction port 44 and the first discharge port 45, but the arrangement of the introduction ports and the discharge ports is not limited to this. For example, only the connection port 48 may be provided in the end plate 43A, and the first introduction port 44, the first discharge port 45, the second introduction port 46, and the second discharge port 47 may be provided in the end plate 43B.

The plate heat exchanger 40 is housed in the outdoor unit 51 and disposed outdoors, but is not limited thereto. The plate heat exchanger 40 may be disposed outdoors alone without being housed in the outdoor unit 51. The plate heat exchanger 40 may be disposed indoors. In this case, the relief valve 30 connected to the plate heat exchanger 40 need not be disposed outdoors, and a relief pipe for releasing the fluid such as the refrigerant discharged from the relief valve 30 to the outside may be connected to the relief valve 30.

The heat medium circulating through the heat medium circuit is water, but the present invention is not limited to this. The heat medium may be an antifreeze such as ethylene glycol, or may be water mixed with an antifreeze. The use-side heat exchanger connected to the heat medium circuit is the heating terminal 23, but the present invention is not limited to this. The use-side heat exchanger may be, for example, a hot water storage tank or the like that has a heat exchange unit therein to generate and retain hot water.

Further, the safety valve 25 is provided in the water circuit 20, but the present invention is not limited to this, and the safety valve 25 may not be provided in the water circuit 20. In this case, as shown in fig. 1, since the relief valve 30 is connected to the water circuit 20, the relief valve 30 can also function as the relief valve 25. That is, for example, even when an abnormal pressure increase occurs in the water circuit 20 due to a factor other than leakage of the refrigerant in the plate heat exchanger 40, the relief valve 30 is opened to release the water in the water circuit 20 to the outside, so that the components, equipment, and the like of the water circuit 20 can be protected from the water pressure. In addition, when the safety valve 25 is provided in the water circuit 20, the water circuit 20 is protected by both the relief valve 30 and the safety valve 25 against hydraulic pressure failure. Therefore, the reliability of the water circuit 20 against the water pressure failure can be improved. For example, even when one of the relief valve 30 and the relief valve 25 fails, the other can protect the water circuit 20. In this case, for example, the set value of the relief valve 25 may be set slightly higher than the set value of the relief valve 30, and when the pressure rises due to leakage of the refrigerant in the plate heat exchanger 40, not the relief valve 25 but the relief valve 30 may be more reliably opened.

(embodiment mode 2)

Next, a heat pump apparatus 2 according to embodiment 2 of the present invention will be described with reference to fig. 7. Fig. 7 is a diagram showing a schematic configuration of the heat pump device 2. Note that the same reference numerals are given to parts having the same configurations as those of the heat pump apparatus 1 according to embodiment 1 described above, and detailed description thereof is omitted.

The heat pump device 2 of the present embodiment is different from the heat pump device 1 of embodiment 1 in that a check valve 26 is provided in the water circuit 20. As shown in fig. 7, a check valve 26 is provided in the water circuit 20 between the pump 22 and the plate heat exchanger 40. The check valve 26 keeps the flow of water in the water circuit 20 always in the direction from the pump 22 toward the plate heat exchanger 40, preventing reverse flow. In the present embodiment, the check valve 26 is housed in the indoor unit 52.

In the plate heat exchanger 40, when the heat transfer plate 41 is damaged and the water flow passage communicates with the refrigerant flow passage, the refrigerant flows into the water flow passage and the pressure in the water flow passage is increased. This generates a pressure in the reverse flow direction in the check valve 26 of the water circuit 20. At this time, the check valve 26 is closed to prevent the water in the water circuit 20 from flowing in the reverse direction, and to stop the flow of the water. Therefore, the refrigerant flowing into the water flow path becomes more difficult to flow from the first introduction port 44 to the water circuit 20, and therefore the refrigerant flowing into the water flow path can be discharged from the relief valve 30 more intensively.

In the heat pump device 2 configured as described above, the same effects as those of the heat pump device 1 according to embodiment 1 can be obtained.

(embodiment mode 3)

Next, a heat pump apparatus 1 according to embodiment 3 of the present invention will be described with reference to fig. 8. Fig. 8 is a sectional view taken along line IV-IV of fig. 3 in a state where the relief valve is mounted. In embodiment 3, the connection between the relief valve 30 and the plate heat exchanger 40 of the heat pump device 1 described in embodiment 1 will be described in more detail. Therefore, the same reference numerals are given to those parts having the same configurations as those of the heat pump apparatus 1 according to embodiment 1 described above, and detailed description thereof will be omitted.

The relief valve 30 includes a first opening portion 30a, a second opening portion 30b, an in-valve passage portion 30c, and a valve body 30 d. The first opening 30a is connected to a connection port 48 of the plate heat exchanger 40. The second opening 30b serves as a discharge port for discharging water or refrigerant in the water circuit 20 when the relief valve 30 is opened. When the relief pipe is connected to the relief valve 30, the relief pipe is connected to the second opening 30 b. The in-valve flow path portion 30c forms a flow path that communicates the first opening portion 30a and the second opening portion 30 b. The valve body 30d is provided midway in the valve internal flow path portion 30 c. The valve body 30d closes the flow path formed by the internal flow path portion 30c when the pressure of the water circuit 20 is equal to or lower than a preset set value. That is, when the pressure in the water circuit 20 is equal to or lower than the set value, the relief valve 30 is in a closed state, the second opening 30b is not communicated with the water circuit 20, and the water or the refrigerant in the water circuit 20 is not discharged from the second opening 30 b. The valve body 30d opens the flow path formed by the internal flow path portion 30c when the pressure of the water circuit 20 exceeds a set value. That is, when the pressure in the water circuit 20 exceeds the set value, the relief valve 30 is in an open state, the second opening 30b communicates with the water circuit 20, and the water or the refrigerant in the water circuit 20 is discharged from the second opening 30 b. Further, the valve body 30d is configured to return to a state of closing the flow path formed by the flow path portion 30c in the valve when the pressure of the water circuit 20 drops to be equal to or lower than the set value after the pressure of the water circuit 20 becomes open in excess of the set value.

The connection port 48 extends from the end plate 43A toward the outside of the plate heat exchanger 40. The first opening 30a of the relief valve 30 is connected to the distal end of the connection port 48. That is, the connection port 48 is connected to the relief valve 30 provided separately from the plate heat exchanger 40. And the relief valve 30 is located entirely outside the plate heat exchanger 40 with respect to the end plate 43A.

As described above, the plate heat exchanger 40 according to embodiment 3 includes: a plurality of heat transfer plates 41 each having a first through-hole 42A, a second through-hole 42B, a third through-hole 42C, and a fourth through-hole 42D that penetrate in one direction, and that are stacked in one direction, and that divide a first flow path (heat medium circuit) through which a first fluid (heat medium) flows and a second flow path (refrigerant circuit) through which a second fluid (refrigerant) flows, and that exchange heat between the first fluid in the first flow path and the second fluid in the second flow path; and a pair of end plates 43 each having a first introduction port 44 connected to the first through hole 42A for introducing the first fluid into the first channel, a first discharge port 45 connected to the second through hole 42B for discharging the first fluid from the first channel, a second introduction port 46 connected to the third through hole 42C for introducing the second fluid into the second channel, a second discharge port 47 connected to the fourth through hole 42D for discharging the second fluid from the second channel, and a branch connection port 48 connected to either one of the first through hole 42A and the second through hole 42B and connected to the first channel branch connection port 48 so as to sandwich the plurality of connection ports 41 in one direction, and the connection port 48 is connected to the relief valve 30 provided separately from the plate heat exchanger 40. This structure is a structure in which the relief valve 30 provided separately from the plate heat exchanger 40 is connected to the connection port 48, and therefore, the range of selection of the relief valve 30 is widened, and the degree of freedom in design is increased. For example, unlike the structure of the present embodiment, when the relief valve and the plate heat exchanger are integrated by using a rubber plug that is elastically deformed and fitted into the connection port, an aluminum band that is attached to the connection port, or the like for the relief valve, adjustment of the set pressure is difficult. However, in the configuration in which the relief valve 30 provided separately from the plate heat exchanger 40 is connected to the connection port 48 as in the present embodiment, a valve having a configuration in which the set pressure can be adjusted can be used as the relief valve 30.

The heat pump device 1 according to embodiment 3 is configured to include: a refrigerant circuit 10 in which a compressor 12, a plate heat exchanger 40, an expansion mechanism 13, and a heat source side heat exchanger are connected via refrigerant pipes 11, and in which a refrigerant circulates; a heat medium circuit in which the pump 22, the plate heat exchanger 40, and the use-side heat exchanger are connected via heat medium pipes and in which a heat medium circulates; and a relief valve 30 connected to a connection port 48 branched from the heat medium circuit in the plate heat exchanger 40 and provided separately from the plate heat exchanger 40. This structure is provided with the relief valve 30 provided separately from the plate heat exchanger 40, and therefore, the range of selection of the relief valve 30 is widened, and the degree of freedom in design is increased.

The heat pump apparatus 1 according to embodiment 3 has, as an additional configuration, a configuration in which the plate heat exchanger 40 includes: a plurality of heat transfer plates 41 each having a first through-hole 42A, a second through-hole 42B, a third through-hole 42C, and a fourth through-hole 42D that penetrate in one direction, and that are stacked in one direction, and that divide a first flow path (heat medium circuit) through which a first fluid (heat medium) flows and a second flow path (refrigerant circuit) through which a second fluid (refrigerant) flows, and that exchange heat between the first fluid in the first flow path and the second fluid in the second flow path; and a pair of end plates 43 each having a first introduction port 44 connected to the first through hole 42A for introducing the first fluid into the first channel, a first discharge port 45 connected to the second through hole 42B for discharging the first fluid from the first channel, a second introduction port 46 connected to the third through hole 42C for introducing the second fluid into the second channel, a second discharge port 47 connected to the fourth through hole 42D for discharging the second fluid from the second channel, and a connection port 48 connected to either one of the first through hole 42A and the second through hole 42B and branched from the first channel, and sandwiching the plurality of heat transfer plates 41 in one direction. With this additional configuration, the heat pump apparatus according to embodiment 3 can prevent the relief valve from being closed by ice generated by cooling water with the refrigerant as described in embodiment 1, and therefore has an effect of being able to more reliably discharge the refrigerant leaking into the water flow path from the water flow path through the relief valve 30.

The heat pump device 1 according to embodiment 3 has, as an additional configuration, a configuration in which the relief valve 30 is opened when the pressure in the heat medium circuit exceeds a preset set value, and is closed when the pressure in the heat medium circuit is equal to or less than the set value after the relief valve 30 is opened. With this additional configuration, the heat pump device according to embodiment 3 has an effect of being able to reduce the amount of the heat medium or the refrigerant flowing out. In particular, when the refrigerant is flammable, the amount of the refrigerant flowing out is reduced, thereby achieving an effect of suppressing the accumulated refrigerant from becoming flammable.

The heat pump apparatus 1 according to embodiment 3 has, as an additional configuration, a configuration in which the entire relief valve 30 is located outside the plate heat exchanger 40. When a part of the relief valve is located inside the plate heat exchanger, the relief valve may interfere with the flow of the fluid flowing through the heat transfer plate, thereby reducing the heat exchange efficiency of the plate heat exchanger. However, with this additional configuration, the relief valve of the heat pump device according to embodiment 3 does not obstruct the flow of the fluid flowing through the heat transfer plate, and a decrease in heat exchange efficiency can be prevented.

The heat pump device 1 according to embodiment 3 has, as an additional configuration, a configuration in which the relief valve 30 is disposed outdoors. With this additional configuration, the heat pump device 1 according to embodiment 3 has an effect of reducing the possibility of suffocation caused by refrigerant gas indoors as described in embodiment 1. In particular, when the refrigerant is flammable, the refrigerant does not flow into the room, and therefore, the possibility of burning of the refrigerant gas in the room can be reduced.

As an additional configuration, the heat pump device 1 according to embodiment 3 has a configuration in which a relief pipe for releasing the fluid discharged from the relief valve 30 to the outside is connected to the relief valve 30. With this additional configuration, the heat pump device 1 according to embodiment 3 has an effect of reducing the possibility of suffocation caused by refrigerant gas indoors as described in embodiment 1. In particular, when the refrigerant is flammable, the refrigerant does not flow into the room, and therefore, the possibility of burning of the refrigerant gas in the room can be reduced.

A modification of embodiment 3 will be described.

The heat pump device 1 according to embodiment 3 may be provided with the check valve 26 described in embodiment 2. That is, the heat pump device according to the modification of embodiment 3 has, as an additional configuration, a configuration in which a check valve is provided between the pump and the plate heat exchanger in the heat medium circuit. With this additional configuration, the heat pump device according to the modification of embodiment 3 has an effect that the refrigerant flowing into the heat medium flow path can be discharged from the relief valve more intensively as described in embodiment 2.

In addition, in the heat pump device 1 according to embodiment 3, the flow path cross-sectional area of the first opening 30a, the flow path cross-sectional area of the second opening 30b, and the flow path cross-sectional area of the flow path formed by the in-valve flow path portion 30c are preferably larger than the flow path cross-sectional area of the connection port 48. The flow path cross-sectional area herein refers to a cross-sectional area of a plane perpendicular to a flow direction of water or refrigerant flowing through the flow path. The flow direction of the water or the refrigerant flowing through the flow path formed by the first opening 30a, the second opening 30b, and the intra-valve flow path portion 30c is the direction in which the water or the refrigerant discharged from the second opening 30b flows in a state where the relief valve 30 is open. That is, the heat pump device according to the modification of embodiment 3 has, as an additional configuration, a configuration in which the relief valve includes a first opening portion connected to the connection port, a second opening portion for discharging the heat medium or the refrigerant, and an intra-valve flow path portion for forming a flow path that communicates the first opening portion and the second opening portion, and a flow path cross-sectional area of the first opening portion, a flow path cross-sectional area of the second opening portion, and a flow path cross-sectional area of the flow path formed by the intra-valve flow path portion are larger than a flow path cross-sectional area of the connection port. With this additional structure, even if ice adheres to the flow path in the relief valve, the relief valve is less likely to be closed.

In the heat pump device 1 according to embodiment 3, the connection port 48 is directly connected to the relief valve 30, but the present invention is not limited thereto. For example, the connection port and the relief valve may be connected via a connection pipe. That is, the heat pump device according to the modification of embodiment 3 has, as an additional configuration, a configuration in which the connection port and the relief valve are connected via a connection pipe. With this additional configuration, the heat pump device according to the modification of embodiment 3 has an effect of expanding the degree of freedom in the disposition of the relief valve. In particular, when the refrigerant is flammable, the relief valve can be disposed at a location separate from a component that becomes an ignition source, such as an electric circuit, and therefore, there is an effect that the possibility of the refrigerant burning can be reduced.

It is preferable that the cross-sectional area of the flow path of the connection pipe is larger than the cross-sectional area of the flow path of the connection port 48. That is, the heat pump device according to the modification of embodiment 3 has, as an additional configuration, a configuration in which the flow path cross-sectional area of the connection pipe is larger than the flow path cross-sectional area of the connection port. With this additional structure, even if ice adheres to the flow path in the relief valve, the relief valve is less likely to be closed.

In the heat pump device 1 according to embodiment 3, the flow path cross-sectional area of the connection port 48 is substantially the same as the flow path cross-sectional area of the first lead-out port 45, but the present invention is not limited thereto. The cross-sectional area of the flow path of the connection port may be larger than the cross-sectional area of the flow path of the first lead-out port. That is, the plate heat exchanger or the heat pump device according to the modification of embodiment 3 has a structure in which the flow passage cross-sectional area of the connection port is larger than the flow passage cross-sectional area of the first lead-out port as an additional structure. In general, the refrigerant easily flows out from the outlet having a large flow path cross-sectional area. That is, when the flow path cross-sectional area of the connection port is larger than the flow path cross-sectional area of the first lead-out port, the refrigerant leaking into the heat medium circuit is more likely to flow out to the connection port having a larger flow path cross-sectional area than the first lead-out port having a smaller flow path cross-sectional area. Therefore, with this additional configuration, the plate heat exchanger or the heat pump device according to the modification of embodiment 3 has an effect that, when the refrigerant leaks into the heat medium circuit, the leaked refrigerant easily flows out to the connection port 48, and the leaked refrigerant can be quickly discharged to the outside.

(embodiment mode 4)

Next, a heat pump apparatus 3 according to embodiment 4 of the present invention will be described with reference to fig. 9 and 10. Fig. 9 is a front view schematically showing a plate heat exchanger according to embodiment 4 of the present invention. Fig. 10 is a cross-sectional view taken along line X-X of fig. 9. Note that the same reference numerals are given to parts having the same configurations as those of the heat pump apparatus 1 according to embodiment 1 described above, and detailed description thereof is omitted.

The heat pump device 3 according to embodiment 4 is different from the heat pump device 1 according to embodiment 1 in that: the plate heat exchanger 40 is provided with a temperature sensor 31. The temperature sensor 31 is, for example, a thermistor.

The temperature sensor 31 is provided on the surface of the end plate 43A. As described in embodiment 1, the end plate 43A is provided with a connection port 48 to which the relief valve 30 is connected, a second introduction port 46, and a second discharge port 47. The temperature sensor 31 is provided near the connection port 48. Therefore, the distance between the temperature sensor 31 and the connection port 48 is smaller than the distance between the temperature sensor 31 and the second introduction port 46 and the distance between the temperature sensor 31 and the second discharge port 47. In addition, when the first introduction port 44 or the first discharge port 45 is provided in the end plate 43A, the distance between the temperature sensor 31 and the connection port 48 is smaller than the distance between the temperature sensor 31 and the first introduction port 44 and the distance between the temperature sensor 31 and the first discharge port 45.

Further, the temperature sensor 31 is provided between the connection port 48 and the end 43A1 of the end plate 43A when viewed from the direction perpendicular to the surface of the end plate 43A. In addition, the second introduction port 46 and the second discharge port 47 are not located between the connection port 48 and the end portion 43A1 of the end plate 43A. That is, the temperature sensor 31 is positioned between the connection port 48 and the end 43A1 of the end plate 43A, and the other introduction port or discharge port provided in the end plate 43A is not positioned between the connection port 48 and the end 43A1 of the end plate 43A.

The temperature sensor 31 detects the temperature of the surface of the end plate 43A. The temperature sensor 31 detects the temperature of the water flowing through the plate heat exchanger 40 because the temperature of the surface of the end plate 43A increases or decreases as the temperature of the water flowing through the plate heat exchanger 40 increases or decreases.

The temperature sensor 31 is connected to a control device, not shown, so as to be able to communicate with the control device. Information relating to the temperature detected by the temperature sensor 31 is sent to the control device. The control device is communicatively connected to at least the compressor 12. The control device can control the compressor 12 based on the received temperature detected by the temperature sensor 31. When the received temperature detected by the temperature sensor 31 is lower than a preset threshold value, the control device stops the operation of the compressor 12. Further, the control device finally stops the pump, the fan, and other elements included in the heat pump device. Preferably, the control device includes a notification unit configured to notify a user of detection of refrigerant leakage. The control device includes a processor for executing a control program, a memory for storing the control program executed by the processor, and a hardware interface for communicably connecting the processor or the memory to the temperature sensor 31 and the compressor 12.

As described above, the plate heat exchanger 40 according to embodiment 4 includes: a plurality of heat transfer plates 41 that are provided with a first through hole 42A, a second through hole 42B, a third through hole 42C, and a fourth through hole 42D that penetrate in one direction, respectively, that overlap in one direction, and that divide a first flow path (heat medium circuit) through which a first fluid (heat medium) flows and a second flow path (refrigerant circuit) through which a second fluid (refrigerant) flows, and that exchange heat between the first fluid in the first flow path and the second fluid in the second flow path; and a pair of end plates 43 each having a first introduction port 44 connected to the first through hole 42A for introducing the first fluid into the first flow path, a first discharge port 45 connected to the second through hole 42B for discharging the first fluid from the first flow path, a second introduction port 46 connected to the third through hole 42C for introducing the second fluid into the second flow path, a second discharge port 47 connected to the fourth through hole 42D for discharging the second fluid from the second flow path, and a connection port 48 connected to either one of the first through hole 42A and the second through hole 42B and branched from the first flow path for connecting to the relief valve 30, and sandwiching the plurality of heat transfer plates 41 in one direction. With this configuration, the plate heat exchanger 40 according to embodiment 4 has an effect of suppressing the closing of the relief valve by ice generated by cooling water with the refrigerant as described in embodiment 1.

As an additional configuration, the plate heat exchanger 40 according to embodiment 4 includes a temperature sensor that detects a temperature of the heat medium flowing through the plate heat exchanger 40. With this additional configuration, the plate heat exchanger 40 according to embodiment 4 has an effect that the temperature sensor 31 can detect the temperature related to the temperature of the refrigerant flowing through the plate heat exchanger 40. When the plate heat exchanger 40 is damaged and refrigerant leakage occurs, the leaked refrigerant is discharged to the outside from the relief valve 30 attached to the plate heat exchanger 40. Therefore, the temperature of the water flow path in the plate heat exchanger 40 drops at the earliest in the entire path of the water circuit 20 in the heat pump device 1. Therefore, with this additional structure, the plate heat exchanger 40 according to embodiment 4 has an effect of being able to detect early when refrigerant leakage occurs.

As an additional configuration, the plate heat exchanger 40 according to embodiment 4 has a configuration in which the temperature sensor 31 is attached to the end plate 43A provided with the connection port 48. When the refrigerant leakage occurs, the leaked refrigerant is discharged to the outside from the relief valve 30 connected to the connection port 48. Therefore, with this additional configuration, the temperature of the end plate 43A provided with the connection port 48 is significantly lower than the temperature of the other end plate 43B, and therefore the plate heat exchanger 40 according to embodiment 4 can more reliably detect refrigerant leakage.

As an additional configuration, the plate heat exchanger 40 according to embodiment 4 has a configuration in which at least one of the first introduction port 44, the first lead-out port 45, the second introduction port 46, and the second lead-out port 47 is provided in the end plate 43A provided with the connection port 48, and the distance between the connection port 48 and the temperature sensor 31 is smaller than the distance between each of the first introduction port 44, the first lead-out port 45, the second introduction port 46, and the second lead-out port 47 provided in the end plate 43A provided with the connection port 48 and the temperature sensor 31. With this additional structure, the temperature detected by the temperature sensor 31 is less susceptible to the temperature of the fluid flowing through the other inlet port or the outlet port, and there is an effect that the influence of the temperature of the fluid in the vicinity of the connection port 48, which is lowered by the leakage of the refrigerant, becomes large. Therefore, the plate heat exchanger 40 according to embodiment 4 can detect the refrigerant leakage more reliably.

As an additional configuration, the plate heat exchanger 40 according to embodiment 4 has a configuration in which the temperature sensor 31 is provided between the connection port 48 and the end 43A1 of the end plate 43A, and the first introduction port 44, the first lead-out port 45, the second introduction port 46, or the second lead-out port 47 is not provided between the connection port 48 and the end 43A1 of the end plate 43A, when viewed in a direction perpendicular to the surface of the end plate 43A on which the connection port 48 is provided. With this additional structure, the temperature detected by the temperature sensor 31 is less likely to be affected by the temperature of the fluid flowing through the other inlet port or the outlet port, and the effect of increasing the influence of the temperature of the fluid near the connection port 48 that is lowered by the refrigerant leakage is obtained. Therefore, the plate heat exchanger 40 according to embodiment 4 can detect the refrigerant leakage more reliably.

The additional configuration of the plate heat exchanger 40 according to embodiment 4 described above may be combined with the heat pump apparatus 1 having the following configuration. The heat pump device 1 is configured to include: a refrigerant circuit 10 in which a compressor 12, a plate heat exchanger 40, an expansion mechanism 13, and a heat source side heat exchanger are connected via refrigerant pipes 11, and in which a refrigerant circulates; a heat medium circuit in which the pump 22, the plate heat exchanger 40, and the use-side heat exchanger are connected via heat medium pipes, and in which a heat medium circulates; and a relief valve 30 connected to a connection port 48 branched from the heat medium circuit in the plate heat exchanger 40.

The heat pump device 1 according to embodiment 4 additionally includes a control device communicably connected to the temperature sensor 31 and the compressor 12, and the control device stops the compressor 12 when the temperature detected by the temperature sensor 31 is lower than a predetermined threshold value. With this additional structure, the compressor can be automatically stopped when refrigerant leakage occurs, and the effect of the refrigerant leakage can be reduced. As an additional configuration, there is a configuration in which the control device finally stops each element included in the pump, the fan, and the other heat pump devices. With this additional structure, the heat pump device can be automatically stopped when refrigerant leakage occurs, and the effect of the refrigerant leakage can be reduced. In addition, as an additional configuration, the control device preferably includes a notification unit configured to notify a user of detection of refrigerant leakage. With this additional configuration, it is possible to notify the user of the occurrence of refrigerant leakage.

A modification of embodiment 4 will be described.

The heat pump apparatus 1 according to embodiment 3 may be configured in the manner described in embodiment 4. The additional configuration described in embodiment 4 may be added to the plate heat exchanger 40 or the heat pump apparatus 1 having the following configuration. The plate heat exchanger 40 includes: a plurality of heat transfer plates 41 each having a first through-hole 42A, a second through-hole 42B, a third through-hole 42C, and a fourth through-hole 42D that penetrate in one direction, and that are stacked in one direction, and that divide a first flow path (heat medium circuit) through which a first fluid (heat medium) flows and a second flow path (refrigerant circuit) through which a second fluid (refrigerant) flows, and that exchange heat between the first fluid in the first flow path and the second fluid in the second flow path; and a pair of end plates 43 provided with a first introduction port 44 connected to the first through hole 42A for introducing the first fluid into the first flow path, a first discharge port 45 connected to the second through hole 42B for discharging the first fluid from the first flow path, a second introduction port 46 connected to the third through hole 42C for introducing the second fluid into the second flow path, a second discharge port 47 connected to the fourth through hole 42D for discharging the second fluid from the second flow path, and a connection port 48 connected to either one of the first through hole 42A and the second through hole 42B and branched from the first flow path, wherein the plurality of connection ports 41 are sandwiched in one direction, and the connection port 48 is connected to the relief valve 30 provided separately from the plate heat exchanger 40. The heat pump device 1 is configured to include: a refrigerant circuit 10 in which a compressor 12, a plate heat exchanger 40, an expansion mechanism 13, and a heat source side heat exchanger are connected via refrigerant pipes 11, and in which a refrigerant circulates; a heat medium circuit in which a pump 22, a plate heat exchanger 40, and a use-side heat exchanger are connected via heat medium pipes, and in which a heat medium circulates; and a relief valve 30 connected to a connection port 48 branched from the heat medium circuit in the plate heat exchanger 40 and provided separately from the plate heat exchanger 40.

Fig. 11 is a cross-sectional view taken along line X-X in fig. 9 of a plate heat exchanger according to a modification of embodiment 4. As shown in fig. 11, the temperature sensor 31 may be provided on the heat transfer plate 41 located on the side surface of the plate heat exchanger 40. That is, the plate heat exchanger according to the modification of embodiment 4 has a structure in which the temperature sensor is attached to the heat transfer plate located on the side surface of the plate heat exchanger as an additional structure. With this additional configuration, the plate heat exchanger according to the modification of embodiment 4 can directly detect the temperature of the surface of the heat transfer plate 41 without passing through the end plate 43A, and therefore, it has an effect that it can be detected early when refrigerant leakage occurs. Further, the temperature sensor 31 is preferably provided on the heat transfer plate 41 located close to the connection port 48 among the plurality of laminated heat transfer plates 41. The temperature of the surface of the heat transfer plate 41 can be directly detected, and the temperature of the outflow side of the leaking refrigerant and water can be detected, so that the detection can be performed at an earlier stage.

The plate heat exchanger according to the modification of embodiment 4 has, as additional components, a configuration in which the distance between the connection port 48 and the temperature sensor 31 is smaller than the distance between the first introduction port 44 and the temperature sensor 31, the distance between the first lead-out port 45 and the temperature sensor 31, the distance between the second introduction port 46 and the temperature sensor 31, and the distance between the second lead-out port 47 and the temperature sensor 31. With this additional structure, the temperature detected by the temperature sensor 31 has an effect that the influence of the temperature of the fluid flowing through the other inlet port or the outlet port is small, and the influence of the temperature of the fluid in the vicinity of the connection port 48, which is lowered by the leakage of the refrigerant, is large. Therefore, the plate heat exchanger 40 according to the modification of embodiment 4 can detect the refrigerant leakage more reliably.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. Addition, omission, replacement, and other changes in configuration may be made within the scope not departing from the spirit of the present invention.

Industrial applicability of the invention

According to the plate heat exchanger and the heat pump device described above, the second fluid leaking to the first flow path can be more reliably discharged from the first flow path through the relief valve while preventing the relief valve from being closed.

Description of the reference numerals

1. 2 … heat pump device; 10 … refrigerant circuit; 11 … refrigerant piping; 12 … compressor; 13 … expansion valve (expansion mechanism); 14 … air heat exchanger (heat source side heat exchanger); 15 … four-way valve; 20 … water circuit (heat medium circuit); 21 … water piping (heat medium piping); 22 … pump; 23 … heating terminal (use side heat exchanger); 24 … expansion tank; 25 … safety valve; 26 … check valve; 30 … pressure relief valve; 30a … first opening; 30b … second opening; 30c … in-valve flow path portion; 30d … valve core; 31 … temperature sensor; 40 … plate heat exchanger; 41 … heat transfer plates; 42A … first through hole; 42B … second through hole; 42C … third through hole; 42D … fourth through hole; 43A, 43B … end plates; 44 … a first inlet; 45 … first outlet port; 46 … second inlet; 47 … second outlet port; port 48 …; 51 … outdoor unit; 52 … indoor unit; a space of 60 …; a … communicating parts.