Heat pump device

Abstract

To provide a heat pump device that can detect that a refrigerant in a refrigerant circuit has entered a water circuit due to damage of a water heat exchanger, etc. without being affected by fluctuations in water temperature and water pressure in the water circuit.SOLUTION: A heat pump device comprises an outdoor heat exchanger 14, a water heat exchanger 17, an indoor heat exchanger 21, a refrigerant pipe 11, a water pipe 30, a pump 18, and an air vent valve 40 capable of discharging gas in the water pipe 30 to the outside. The water pipe 30 comprises an approach passage water pipe 31 through which water flows toward the indoor heat exchanger 21 from the water heat exchanger 17, and a return passage water pipe 32 through which water flows toward the water heat exchanger 17 from the indoor heat exchanger 21. The air vent valve 40 is provided in the approach passage water pipe 31. The heat pump device also comprises a flowmeter 50 provided in the approach passage water pipe 31 between the water heat exchanger 17 and the air vent valve 40, and a refrigerant entry detection unit 120 for detecting the entry of a refrigerant into the water pipe 30 on the basis of a detection result of the flowmeter 50.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a heat pump device. [Background technology]

[0002] In a heat medium circulation system that includes a heat pump cycle (refrigerant circuit) in which a refrigerant circulates, a heating cycle (water circuit) in which a heat medium (water) heated in the heat pump cycle circulates between the heat pump cycle and a heating terminal, a pressure sensor that detects the pressure of the heat medium in the heating cycle, and a control device, the control device is known to determine that refrigerant has leaked from the heat pump cycle into the heating cycle when the detection value of the pressure sensor in the heat medium circulation system is equal to or greater than a predetermined value (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2023-041134 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a heat pump apparatus such as that disclosed in Patent Document 1, the water pressure in the water circuit increases as the water temperature in the water circuit increases. When the water pressure increases due to the increase in water temperature in the water circuit, there is a risk of false detection that refrigerant has entered the water circuit from the refrigerant circuit. Furthermore, if the pressure sensor's judgment reference value is set high to avoid such false detection, it takes time for the pressure sensor's detection value to exceed the judgment reference value, particularly when the water temperature in the water circuit is low, to be detected.

[0005] The present disclosure has been made to solve such problems, and its purpose is to provide a heat pump apparatus that can detect when refrigerant in a refrigerant circuit has entered the water circuit due to damage to a water heat exchanger or the like, without being affected by fluctuations in water temperature and water pressure in the water circuit. [Means for solving the problem]

[0006] A heat pump device according to the present disclosure includes a first heat exchanger that exchanges heat between a refrigerant and air, a second heat exchanger that exchanges heat between the refrigerant and water, a third heat exchanger that exchanges heat between the water and air, a refrigerant pipe that connects the first heat exchanger and the second heat exchanger in a ring shape and has the refrigerant inside, a water pipe that connects the second heat exchanger and the third heat exchanger in a ring shape and has the water inside, a pump that circulates water in the water pipe, and an air vent valve that can discharge gas inside the water pipe to the outside. The water piping includes an outward water piping through which the water flows from the second heat exchanger to the third heat exchanger, and a return water piping through which the water flows from the third heat exchanger to the second heat exchanger, and the air vent valve is provided in the outward water piping, and is provided between the second heat exchanger and the air vent valve in the outward water piping, and further includes a flow meter that detects the flow rate of water in the outward water piping, and a refrigerant intrusion detection unit that detects the intrusion of the refrigerant into the water piping based on the detection result of the flow meter.

[0007] Alternatively, the heat pump device according to the present disclosure includes a first heat exchanger that exchanges heat between a refrigerant and air, a second heat exchanger that exchanges heat between the refrigerant and water, a third heat exchanger that exchanges heat between the water and air, a refrigerant pipe that connects the first heat exchanger and the second heat exchanger in a ring and has the refrigerant inside, a water pipe that connects the second heat exchanger and the third heat exchanger in a ring and has the water inside, a pump that circulates the water in the water pipe, and an air vent valve that can discharge gas in the water pipe to the outside, wherein the water pipe has an outward water pipe through which the water flows from the second heat exchanger to the third heat exchanger, and a return water pipe through which the water flows from the third heat exchanger to the second heat exchanger, and the air vent valve is provided in the outward water pipe and further includes a bubble detection means that detects air bubbles in the water in the outward water pipe between the second heat exchanger and the air vent valve. [Effects of the Invention]

[0008] The heat pump device according to the present disclosure has the advantage of being able to detect when refrigerant in the refrigerant circuit has entered the water circuit due to damage to the water heat exchanger, etc., without being affected by fluctuations in water temperature and water pressure in the water circuit. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the configuration of a primary circuit and a secondary circuit of an air conditioner to which a heat pump device according to a first embodiment is applied. [Figure 2] 1 is a diagram schematically illustrating a configuration of a main part of a heat pump device according to a first embodiment. [Figure 3] 1 is a block diagram showing the configuration of a control system of a heat pump device according to a first embodiment. [Figure 4] 1 is a block diagram showing a configuration of a control device for a heat pump device according to a first embodiment. [Figure 5] 5 is a diagram showing an example of a change over time in a flow meter measurement value when a refrigerant enters a water pipe of the heat pump device according to the first embodiment. FIG. [Figure 6]FIG. 3 is a diagram illustrating an example of setting the length of water pipes in the heat pump device according to the first embodiment. [Figure 7] FIG. 4 is a diagram schematically illustrating a configuration of a main part of a first modified example of the heat pump device according to the first embodiment. [Figure 8] FIG. 10 is a diagram schematically illustrating a configuration of a main part of a second modified example of the heat pump device according to the first embodiment. [Figure 9] FIG. 10 is a diagram schematically illustrating a configuration of a main part of a third modified example of the heat pump device according to the first embodiment. [Figure 10] 3 is a diagram illustrating an example of a configuration for realizing the functions of a control unit of the heat pump device according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Embodiments of a heat pump apparatus according to the present disclosure will be described with reference to the accompanying drawings. In each drawing, identical or corresponding parts are designated by the same reference numerals, and redundant descriptions will be appropriately simplified or omitted. For convenience, the following description may express the positional relationship of each structure based on the illustrated state. Note that the present disclosure is not limited to the following embodiments, and any combination of the embodiments, any modification of any component of each embodiment, or any omission of any component of each embodiment are possible within the scope of the present disclosure.

[0011] Embodiment 1 A first embodiment of the present disclosure will be described with reference to FIGS. 1 to 10. FIG. 1 is a diagram illustrating the configuration of a primary circuit and a secondary circuit of an air conditioner to which a heat pump device is applied. FIG. 2 is a diagram schematically illustrating the configuration of a main part of a heat pump device. FIG. 3 is a block diagram illustrating the configuration of a control system of a heat pump device. FIG. 4 is a block diagram illustrating the configuration of a control device of a heat pump device. FIG. 5 is a diagram illustrating an example of time changes in flow meter measurement values ​​when refrigerant enters the water piping of a heat pump device. FIG. 6 is a diagram illustrating an example of setting the water piping length of a heat pump device. FIG. 7 is a diagram schematically illustrating the configuration of a main part of a first modified example of a heat pump device. FIG. 8 is a diagram schematically illustrating the configuration of a main part of a second modified example of a heat pump device. FIG. 9 is a diagram schematically illustrating the configuration of a main part of a third modified example of a heat pump device. FIG. 10 is a diagram illustrating an example of a configuration that realizes the functions of a control unit of a heat pump device.

[0012] The following describes an example in which a heat pump device according to this disclosure is applied to an air conditioner. This disclosure can be applied to air conditioners including room air conditioners and commercial packaged air conditioners, as well as water heaters, showcases, refrigerators, chiller systems, etc., and can be used in heat pump devices that have a primary circuit (refrigerant circuit) through which a refrigerant circulates and a secondary circuit (heat medium circuit) through which a liquid heat medium (for example, water) circulates.

[0013] As shown in Fig. 1, an air conditioner to which a heat pump device according to this embodiment is applied includes an outdoor unit 10 and an indoor unit 20. The indoor unit 20 is installed inside the room 2 to be air-conditioned. The outdoor unit 10 is installed outside the room 1. The outdoor unit 10 includes refrigerant piping 11, a compressor 12, a four-way valve 13, an outdoor heat exchanger 14, an outdoor fan 15, an expansion valve 16, a water heat exchanger 17, and a pump 18. The indoor unit 20 includes an indoor heat exchanger 21 and an indoor fan 22.

[0014] Refrigerant piping 11 is provided in a circulating manner between the outdoor heat exchanger 14 and the water heat exchanger 17 of the outdoor unit 10. A refrigerant is sealed in the refrigerant piping 11. From the viewpoint of protecting the global environment, it is desirable to use a refrigerant with a small global warming potential (GWP) as the refrigerant sealed in the refrigerant piping 11. This refrigerant has a larger average molecular weight than air (it has a higher density than air), and has the property of sinking downward in the direction of gravity (vertical direction) in the air.

[0015] Specific examples of such refrigerants that can be used include (mixed) refrigerants made of one or more refrigerants selected from tetrafluoropropene (CFCF=CH:HFO-1234yf), difluoromethane (CHF:R32), propane (R290), propylene (R1270), ethane (R170), butane (R600), isobutane (R600a), and 1.3.3.3-tetrafluoro-1-propene (CF-CH=CHF:HFO-1234ze). Specific examples of refrigerant mixtures include R516A, R445A, R444A, R454C, R444B, R454A, R455A, R457A, R459B, R452B, R454B, R447B, R447A, R446A, R459A, R474A, R479A, etc. These refrigerants include those that are flammable (slightly flammable or highly flammable).

[0016] The refrigerant piping 11 connects the compressor 12, the four-way valve 13, the outdoor heat exchanger 14, the expansion valve 16, and the water heat exchanger 17 in a ring shape. This forms a refrigerant circuit in which the refrigerant circulates between the outdoor heat exchanger 14 and the water heat exchanger 17.

[0017] The compressor 12 is a device that compresses the supplied refrigerant to increase the pressure and temperature of the refrigerant. The compressor 12 may be, for example, a rotary compressor or a scroll compressor. The four-way valve 13 is a valve that switches whether the discharge side of the compressor 12 is connected to the outdoor heat exchanger 14 or the water heat exchanger 17. By switching the four-way valve 13, the circulation direction of the refrigerant in the refrigerant circuit can be reversed.

[0018] The expansion valve 16 expands the refrigerant that has flowed in, thereby reducing the pressure of the refrigerant. In other words, the expansion valve 16 is a pressure reducing device that reduces the pressure of the refrigerant. In the configuration example described here, the expansion valve 16 is a linear electric expansion valve (LEV). Therefore, by closing the expansion valve 16, the flow of the refrigerant can be prevented.

[0019] The outdoor heat exchanger 14 is a heat source-side air heat exchanger that exchanges heat between the refrigerant that flows into the outdoor heat exchanger 14 and the air. The outdoor fan 15 generates an airflow in an air passage in the outdoor unit housing, which will be described later, and blows the outside air so that it passes around the outdoor heat exchanger 14. The outdoor heat exchanger 14 evaporates or condenses the flowing refrigerant, thereby exchanging heat with the outdoor air 1 sent from the outdoor fan 15 and cooling or heating the air. In this way, the outdoor fan 15 is a blower fan that generates an airflow that passes around the outdoor heat exchanger 14, which is a heat source-side air heat exchanger.

[0020] The outdoor unit 10 and the indoor unit 20 are connected by a water pipe 30. The water pipe 30 is provided in a circulating manner between the water heat exchanger 17 of the outdoor unit 10 and the indoor heat exchanger 21 of the indoor unit 20. Water, which is a liquid heat medium, is sealed inside the water pipe 30. In other words, the water pipe 30 is a heat medium pipe in which water, which is a liquid heat medium, is placed. Water is one example of a liquid heat medium. Other liquid heat mediums such as brine can also be used.

[0021] The water heat exchanger 17 is a liquid heat exchanger that exchanges heat between the refrigerant that has flowed into the water heat exchanger 17 and water (liquid heat medium). For example, a plate heat exchanger or a double-pipe heat exchanger, which have high heat exchange efficiency, is used as the water heat exchanger 17.

[0022] The pump 18 is provided in the water piping 30. The pump 18 is used to cause water, which is a liquid heat medium, to flow through the water heat exchanger 17. The water piping 30 connects the indoor heat exchanger 21, the water heat exchanger 17, and the pump 18 in a ring shape. Therefore, a water circuit is formed in which water is circulated between the indoor heat exchanger 21 and the water heat exchanger 17 by the pump 18.

[0023] The pump 18 causes water (liquid heat medium) to flow in a predetermined circulation direction through the water piping 30 (heat medium piping) formed in a ring shape in this way. This circulation direction is the direction in which the water, which is the liquid heat medium, passes through the pump 18, the water heat exchanger 17, which is a liquid heat exchanger, and the indoor heat exchanger 21, which is a load-side air heat exchanger, in that order.

[0024] The indoor heat exchanger 21 is a load-side air heat exchanger that exchanges heat between water (liquid heat medium) that flows into the indoor heat exchanger 21 and air. The indoor fan 22 generates an airflow in an air path inside the indoor unit housing, which will be described later, and sends the air so that it passes around the indoor heat exchanger 21. The indoor heat exchanger 21 heats or cools the air in the room 2 by exchanging heat between the high-temperature or low-temperature water that flows into the indoor heat exchanger 21 and the air in the room 2 that is sent from the indoor fan 22.

[0025] The outdoor heat exchanger 14 in this embodiment is an example of a first heat exchanger that exchanges heat between a refrigerant and air. The water heat exchanger 17 in this embodiment is an example of a second heat exchanger that exchanges heat between a refrigerant and water. The indoor heat exchanger 21 in this embodiment is an example of a third heat exchanger that exchanges heat between water and air. The refrigerant piping 11 connects the first heat exchanger and the second heat exchanger in a circular configuration.

[0026] Furthermore, the water piping 30 connects the second heat exchanger and the third heat exchanger in a ring shape. The water piping 30 has an outgoing water piping 31 and a return water piping 32. The outgoing water piping 31 is a piping through which water flows from the water heat exchanger 17, which is the second heat exchanger, to the indoor heat exchanger 21, which is the third heat exchanger. The return water piping 32 is a piping through which water flows from the third heat exchanger, i.e., the indoor heat exchanger 21, to the second heat exchanger, i.e., the water heat exchanger 17. In the configuration example described here, the outgoing water piping 31 is arranged vertically above the return water piping 32.

[0027] The outdoor unit 10 includes an outdoor unit housing. The outdoor unit housing is a heat source side housing. Inside the outdoor unit housing, refrigerant piping 11, a compressor 12, a four-way valve 13, an outdoor heat exchanger 14, an outdoor fan 15, an expansion valve 16, a water heat exchanger 17, a pump 18, and part of the water piping 30 are housed. The indoor unit 20 includes an indoor unit housing. Inside the indoor unit housing, an indoor heat exchanger 21, an indoor fan 22, and part of the water piping 30 are housed.

[0028] The outdoor unit housing has an air inlet and an air outlet that connect the inside of the outdoor unit housing with the outside. Inside the outdoor unit housing, an air path is formed that runs from the air inlet through the outdoor heat exchanger 14 and the outdoor fan 15 to the air outlet. This air path is for releasing air taken in from outside the outdoor unit housing to the outside of the outdoor unit housing after heat exchange in the outdoor heat exchanger 14. Note that the indoor unit housing also has an air inlet, an air outlet, and an air path formed therein.

[0029] The refrigerant circuit and water circuit configured in this manner function as a heat pump that transfers heat between the indoor unit 20 and the outdoor unit 10 by performing heat exchange between the refrigerant and air in the outdoor heat exchanger 14, heat exchange between the refrigerant and water in the water heat exchanger 17, and further heat exchange between water and air in the indoor heat exchanger 21. In other words, this is an indirect type air conditioner that uses a primary circuit (refrigerant circuit) in which a flammable refrigerant circulates and a secondary circuit in which a non-flammable heat medium (water in this case) circulates.

[0030] By switching the four-way valve 13, the direction of refrigerant circulation in the refrigerant circuit can be reversed to switch between cooling operation and heating operation. In cooling operation, the four-way valve 13 connects the discharge side of the compressor 12 to the outdoor heat exchanger 14. In the present disclosure, connecting the discharge side of the compressor 12 to the outdoor heat exchanger 14 using the four-way valve 13 is also referred to as "setting the four-way valve 13 for cooling." On the other hand, in heating operation, the four-way valve 13 connects the discharge side of the compressor 12 to the water heat exchanger 17 using the four-way valve 13. In the present disclosure, connecting the discharge side of the compressor 12 to the water heat exchanger 17 using the four-way valve 13 is also referred to as "setting the four-way valve 13 for heating."

[0031] During cooling operation, in the primary refrigerant circuit, the refrigerant is heated to a high temperature and pressure by the compressor 12, passes through the four-way valve 13, and flows into the outdoor heat exchanger 14. At this time, the outdoor heat exchanger 14 functions as a condenser and condenses the refrigerant that has flowed in. That is, the high-temperature refrigerant that has flowed into the outdoor heat exchanger 14 exchanges heat with the low-temperature outside air, condenses, and becomes liquid refrigerant.

[0032] The liquid refrigerant expands through expansion valve 16, becoming a two-phase gas-liquid refrigerant at low temperature and low pressure, where the gas and liquid phases are mixed. This low-temperature two-phase gas-liquid refrigerant flows into water heat exchanger 17, where it exchanges heat with the water circulating in the water circuit and evaporates to become gas refrigerant. This heat exchange cools the water in the water circuit. That is, water heat exchanger 17 acts as a heat absorber that absorbs heat from the water in the water circuit, cooling the water. The gas refrigerant passes through four-way valve 13 and flows back into compressor 12, becoming a high-temperature, high-pressure refrigerant.

[0033] In the water circuit, water is circulated by the pressure generated by the pump. The water cooled in the water heat exchanger 17 and cooled to a low temperature flows from the water pipe 30 in the outdoor unit housing to the water pipe 30 in the indoor unit housing while remaining at a low temperature. The low-temperature water flowing through the water pipe 30 in the indoor unit housing flows into the indoor heat exchanger 21.

[0034] The water that flows into the indoor heat exchanger 21 exchanges heat with the indoor air and is heated. During this process, the indoor air is cooled. The heated water flows into the water piping 30 inside the outdoor unit housing, passes through the pump 18, and flows back into the water heat exchanger 17 where it is cooled and becomes low-temperature water.

[0035] During heating operation, in the primary refrigerant circuit, the refrigerant is heated to a high temperature and pressure by the compressor 12 and flows through the four-way valve 13 into the water heat exchanger 17. The refrigerant that flows into the water heat exchanger 17 exchanges heat with the water circulating in the water circuit, condensing and becoming liquid refrigerant. At this time, the water circulating in the water circuit is heated. In other words, the water heat exchanger 17 functions as a radiator and heats the water flowing in the water circuit.

[0036] The liquid refrigerant passes through expansion valve 16 and expands to become a low-temperature, low-pressure two-phase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flows into outdoor heat exchanger 14. At this time, outdoor heat exchanger 14 functions as an evaporator and evaporates the refrigerant that has flowed in. That is, the two-phase gas-liquid refrigerant that has flowed into outdoor heat exchanger 14 exchanges heat with outside air and evaporates to become gas refrigerant. The gas refrigerant flows back into compressor 12 through four-way valve 13 and becomes a high-temperature, high-pressure refrigerant.

[0037] In the water circuit, water is circulated by the pressure generated by the pump 18. First, low-temperature water cooled by the water heat exchanger 17 flows, while still at high temperature, from the water piping 30 in the outdoor unit housing to the water piping 30 in the indoor unit housing. The high-temperature water flowing through the water piping 30 in the indoor unit housing flows into the indoor heat exchanger 21.

[0038] The water that flows into the indoor heat exchanger 21 exchanges heat with the indoor air and is cooled. During this process, the indoor air is heated. The cooled water flows into the water piping 30 inside the outdoor unit housing, passes through the pump 18, and flows back into the water heat exchanger 17 where it is heated and becomes high-temperature water.

[0039] The water pipe 30 is provided with a pressure valve 33. The pressure valve 33 is a control valve that opens the water pipe 30 when the internal pressure of the water pipe 30 reaches or exceeds a preset operating pressure, thereby making the internal pressure of the water pipe 30 constant. The pressure valve 33 does not have to be provided directly on the water pipe 30, but may also be provided on a pipe branching off from the water pipe 30. In the illustrated configuration example, the pressure valve 33 is provided on the return water pipe 32, which is located inside the room 2.

[0040] The heat pump device according to this embodiment includes an air vent valve 40. The air vent valve 40 is provided in a portion of the water piping 30 that is housed in the outdoor unit housing. In other words, the air vent valve 40 is housed inside the housing of the outdoor unit 10.

[0041] The air vent valve 40 is a valve that can discharge gases such as air inside the water piping 30 to the outside. For example, a float-type automatic air vent valve is used as the air vent valve 40. A float-type automatic air vent valve has a sealing function that prevents backflow of air using a float, and can discharge only gases in the water. More specifically, under normal circumstances, the inside of the air vent valve 40 is filled with water, and the opening and the float are tightly sealed. When air accumulates inside the air vent valve 40, the float floats on the water and descends to the water surface, creating a gap between the opening and the float, allowing only the air to be discharged to the outside.

[0042] The air vent valve 40 is provided on the outflow water pipe 31. The pump 18 is provided on the return water pipe 32. The presence of air in the water pipe 30 of the water circuit, etc., hinders the smooth flow of water. Furthermore, if air enters the pump 18, it may run idle (so-called "air trapping"), making it impossible to circulate water. If air enters the water circuit, the air circulates through the water circuit along with the water, which serves as a heat medium, when the air conditioner is in cooling or heating operation. When the air circulating through the water circuit passes through the air vent valve 40 provided on the outflow water pipe 31, the air is expelled from the air vent valve 40 to the outside of the water circuit. In this way, air is prevented from entering the pump 18, and the pump 18 can be prevented from running idle.

[0043] As shown in Fig. 2, the heat pump device includes a flow meter 50. The flow meter 50 is provided in the outflow water piping 31 between the water heat exchanger 17 and the air vent valve 40. The flow meter 50 is an instrument or sensor that detects the flow rate of water in the outflow water piping 31.

[0044] The air conditioner, which is a heat pump device, is equipped with a control device 100. Fig. 3 is a block diagram showing the configuration of a control system for the heat pump device according to this embodiment. The control device 100 controls the overall operation of the air conditioner, including the operation of the compressor 12, four-way valve 13, outdoor fan 15, expansion valve 16, pump 18, and indoor fan 22. Furthermore, the control device 100 in this embodiment particularly controls the operation of the compressor 12, expansion valve 16, and pump 18 based on the detection results of a flow meter 50.

[0045] 4, the control device 100 includes a control unit 110 and a refrigerant intrusion detection unit 120. The control unit 110 controls the operations of the compressor 12, four-way valve 13, outdoor fan 15, expansion valve 16, pump 18, and indoor fan 22. The refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into the water piping 30 based on the detection result of the flow meter 50.

[0046] In the heat pump device configured as described above, when the air conditioner is in cooling operation, low-temperature refrigerant flows into the water heat exchanger 17. At this time, refrigerant below 0 degrees Celsius (the freezing point of water) may flow into the water heat exchanger 17, causing the water circulating in the water circuit to freeze, and the volume of the water to expand due to freezing may damage the water heat exchanger 17. In addition, the water heat exchanger 17 may also be damaged due to, for example, aging, external stress, etc.

[0047] If the water heat exchanger 17 is damaged, the refrigerant flow path and the water flow path may become connected in the water heat exchanger 17. In this case, the internal pressure of the refrigerant pipe 11 is higher than the internal pressure of the water pipe 30, and therefore, the refrigerant in the refrigerant pipe 11 of the refrigerant circuit may enter the water pipe 30 of the water circuit.

[0048] The refrigerant that flows into the water heat exchanger 17 during heating operation is a high-temperature, high-pressure gas refrigerant compressed by the compressor 12. Therefore, if the water heat exchanger 17 is damaged during heating operation and the refrigerant flow path and water flow path in the water heat exchanger 17 become connected, the refrigerant in a gaseous state will enter the water piping 30 of the water circuit, and the entered refrigerant will flow in the water circuit in its gaseous state.

[0049] Furthermore, the refrigerant that flows into the water heat exchanger 17 during cooling operation is a low-temperature two-phase gas-liquid refrigerant. Therefore, if the water heat exchanger 17 is damaged during cooling operation and the refrigerant flow path and the water flow path in the water heat exchanger 17 become connected, the two-phase gas-liquid refrigerant will enter the water piping 30 of the water circuit. Of these, the liquid phase refrigerant is heated by the water and vaporizes when it enters the water piping 30. On the other hand, the gas phase refrigerant remains in gas form. Therefore, even during cooling operation, the refrigerant that enters the water piping 30 flows in the water circuit in gaseous form. In other words, during both heating operation and cooling operation, the refrigerant that enters the water piping 30 flows in gaseous form within the water circuit.

[0050] The refrigerant gas that has entered the water circuit in the water heat exchanger 17 flows together with water through the outgoing water piping 31 from the water heat exchanger 17 toward the indoor heat exchanger 21 due to the pressure generated by the pump 18. In the outgoing water piping 31, a gas-liquid two-phase flow is formed, in which liquid-phase water and gas-phase refrigerant flow simultaneously. The flow pattern of the gas-liquid two-phase flow in the horizontal flow path changes depending on the liquid-phase flow velocity in the region where the gas-phase flow velocity is approximately slower than 1 m / s. In particular, bubbly flow is dominant at the liquid-phase flow velocity when the pump 18 is operating normally. In bubbly flow, the gas phase exists as bubbles that are evenly distributed throughout the liquid phase.

[0051] FIG. 5 shows an example of the flow rate detection result by the flow meter 50 when the flow in the outbound water pipe 31 changes from a purely liquid-phase flow (i.e., a flow of only water without air bubbles) to a two-phase gas-liquid bubbly flow. As shown in the figure, when air bubbles enter the water flow, the flow rate detected by the flow meter 50 drops significantly, even though the speed of the water flow itself does not decrease significantly. Therefore, in this configuration example, as described above, the refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into the water pipe 30 based on the detection value of the flow meter 50. More specifically, for example, the refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into the water pipe 30 when the flow rate detected by the flow meter 50 falls below a preset reference flow rate. When the refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into the water pipe 30, it may output a refrigerant intrusion detection signal. The refrigerant intrusion detection signal is a signal indicating that the intrusion of refrigerant into the water pipe 30 has been detected.

[0052] With the heat pump apparatus configured as described above, when bubbles of refrigerant gas that have entered the water piping 30 reach the flow meter 50 between the water heat exchanger 17 and the air vent valve 40, it is possible to detect that refrigerant has entered the water circuit. This makes it possible to detect that refrigerant has entered the water circuit without being affected by fluctuations in water temperature and water pressure in the water circuit. This also makes it possible to improve the accuracy of detection when refrigerant has entered the water circuit and shorten the time required for detection.

[0053] When refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into water piping 30, control unit 110 performs preset refrigerant intrusion detection control. In refrigerant intrusion detection control, control unit 110, for example, stops pump 18. By stopping pump 18, the flow rate of water in water piping 30, i.e., the flow rate of the liquid phase, is slowed, or the flow rate in water piping 30 is set to 0 m / s, resulting in a state where there is no water flow and gas and liquid are separated, and refrigerant gas present in the gas phase in water piping 30 can be efficiently discharged to the outside of water piping 30 through air vent valve 40.

[0054] In addition, for example, the control unit 110 stops the compressor 12 in the refrigerant intrusion detection control. At this time, if the expansion valve 16 is an LEV as described above, the control device 100 may stop the compressor 12 and close the expansion valve 16. In this way, the flow of refrigerant in the refrigerant pipe 11 can be blocked. Note that the means for blocking the flow of refrigerant is not limited to the expansion valve 16, which is an LEV. A shut-off valve may be provided in the refrigerant pipe 11 separately from the expansion valve 16. According to this refrigerant intrusion detection control, the flow of refrigerant in the refrigerant pipe 11 can be stopped, thereby suppressing further intrusion of refrigerant into the water pipe 30. Note that the control unit 110 may stop the operation of the heat pump device itself in the refrigerant intrusion detection control.

[0055] FIG. 6 illustrates an example of setting the length of the water pipe 30 from the flowmeter 50 to the air vent valve 40 in the heat pump apparatus of this embodiment. The time when refrigerant gas bubbles that have entered the water pipe 30 in the water heat exchanger 17 reach the flowmeter 50 is defined as T0. Then, the time when the refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into the water pipe 30 as the bubbles reach the flowmeter 50 is defined as T1. A certain time lag T (= T1 - T0) occurs between T0 and T1. The length L of the water pipe 30 from the flowmeter 50 to the air vent valve 40 should be equal to or greater than the product of this time lag T and the maximum flow velocity V of water in the water pipe 30 when the pump 18 is operating. That is, the locations of the flowmeter 50 and the air vent valve 40 should be determined so that the following equation (1) holds:

[0056] L ≥ T × V (1)

[0057] In this way, the pump 18 can be stopped by the refrigerant intrusion detection control before the refrigerant gas bubbles that have infiltrated into the water piping 30 in the water heat exchanger 17 reach the air vent valve 40. Therefore, the refrigerant gas bubbles that have infiltrated into the water piping 30 can be discharged from the air vent valve 40 to the outside of the water piping 30. The maximum flow velocity V in the water piping 30 can be determined from the specifications of the heat pump device, such as the performance of the pump 18.

[0058] 6, the air vent valve 40 is provided at the highest point (vertically above) of the outflow water piping 31. In this manner, gas-phase refrigerant that has entered the water circuit can be guided to the air vent valve 40 and efficiently discharged from the air vent valve 40. In the example shown in the figure, the outflow water piping 31 is disposed vertically above the return water piping 32. For this reason, the air vent valve 40 is provided at the highest point not only of the outflow water piping 31 but also of the entire water piping 30.

[0059] Next, modified examples of the heat pump apparatus according to this embodiment will be described with reference to Figs. 7 to 9. First, Fig. 7 shows a first modified example of this embodiment. In this first modified example, two flow meters, a first flow meter 51 and a second flow meter 52, are provided. The first flow meter 51 corresponds to the flow meter 50 described above. That is, the first flow meter 51 is provided in the outgoing water piping 31, between the water heat exchanger 17 and the air vent valve 40. The first flow meter 51 is an instrument or sensor that detects the flow rate of water in the outgoing water piping 31.

[0060] The second flow meter 52 is provided in the water piping 30 downstream of the air vent valve 40. That is, the second flow meter 52 is provided in the outflow water piping 31 between the air vent valve 40 and the indoor heat exchanger 21, in the return water piping 32 between the indoor heat exchanger 21 and the pump 18, or in the return water piping 32 between the pump 18 and the water heat exchanger 17. In the illustrated example, the second flow meter 52 is provided in the return water piping 32 between the pump 18 and the water heat exchanger 17.

[0061] In this first modified example, the refrigerant intrusion detection unit 120 of the control device 100 detects the intrusion of refrigerant into the water piping 30 based on the detection values ​​of the first flow meter 51 and the second flow meter 52. More specifically, for example, the refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into the water piping 30 when the flow rate detected by the first flow meter 51 is equal to or less than the reference flow rate and the flow rate detected by the second flow meter 52 is not equal to or less than the reference flow rate.

[0062] On the other hand, if the flow rate detected by the first flow meter 51 and the flow rate detected by the second flow meter 52 are both equal to or lower than the reference flow rate, the refrigerant intrusion detection unit 120 does not detect the intrusion of refrigerant into the water piping 30. In this case, the control device 100 detects an abnormality other than the intrusion of refrigerant into the water piping 30, such as the intrusion of foreign matter into the water piping 30 or an extreme decrease in the flow rate of the water piping 30 due to clogging of the water piping 30. According to this first modified example, it is possible to distinguish between the intrusion of refrigerant into the water piping 30 and other flow rate abnormalities in the water piping 30 and detect them.

[0063] Next, Fig. 8 shows a second modified example of this embodiment. In this second modified example, an ultrasonic sensor 60 is provided instead of the flow meter 50. As in the case of the flow meter 50, the ultrasonic sensor 60 is provided in the outflow water piping 31, between the water heat exchanger 17 and the air vent valve 40. The ultrasonic sensor 60 includes an ultrasonic transmitter 61 and an ultrasonic receiver 62. The ultrasonic transmitter 61 and the ultrasonic receiver 62 are arranged opposite each other with the outflow water piping 31 in between.

[0064] The ultrasonic transmitter 61 emits ultrasonic waves toward the water in the outflow water pipe 31. The frequency of the ultrasonic waves emitted by the ultrasonic transmitter 61 is set in advance. The ultrasonic receiver 62 receives ultrasonic waves at the frequency emitted by the ultrasonic transmitter 61. If there are no air bubbles in the water in the outflow water pipe 31, the ultrasonic waves emitted from the ultrasonic transmitter 61 reach the ultrasonic receiver 62 with almost no scattering.

[0065] On the other hand, if air bubbles are present in the water in the outflow water piping 31, the ultrasonic waves emitted from the ultrasonic transmitter 61 are scattered by the air bubbles. Therefore, when air bubbles are present in the water in the outflow water piping 31, the intensity of the ultrasonic waves received by the ultrasonic receiver 62 is reduced compared to when no bubbles are present. Therefore, the presence or absence of bubbles in the water in the outflow water piping 31 can be detected based on the intensity of the ultrasonic waves received by the ultrasonic receiver 62. The ultrasonic sensor 60 is a bubble detection means that detects air bubbles in the water in the outflow water piping 31 between the water heat exchanger 17 and the air vent valve 40.

[0066] In this second modified example, the refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into the water pipe 30 based on the detection result of the ultrasonic sensor 60. As described above, if the refrigerant in the refrigerant pipe 11 of the refrigerant circuit intrudes into the water pipe 30 of the water circuit due to damage to the water heat exchanger 17, the intruding refrigerant flows in a gaseous state through the water pipe 30, and refrigerant bubbles are present in the water flow in the water pipe 30. If the intensity of the ultrasonic waves received by the ultrasonic receiver 62 of the ultrasonic sensor 60 is equal to or less than a predetermined reference ultrasonic intensity, the refrigerant intrusion detection unit 120 detects the presence of bubbles in the water in the water pipe 30 and the intrusion of refrigerant into the water pipe 30. This second modified example also makes it possible to detect the intrusion of refrigerant into the water pipe 30 without being affected by fluctuations in the water temperature and water pressure in the water circuit.

[0067] Next, Figure 9 shows a third modified example of this embodiment. In this third modified example, an optical sensor 70 is provided instead of the flow meter 50. As in the case of the flow meter 50, the optical sensor 70 is provided in the outflow water piping 31, between the water heat exchanger 17 and the air vent valve 40. The optical sensor 70 includes a light-emitting unit 71 and a light-receiving unit 72. The light-emitting unit 71 and the light-receiving unit 72 are arranged opposite each other with the outflow water piping 31 in between.

[0068] The light-emitting unit 71 irradiates light toward the water in the outflow water pipe 31. The wavelength (or frequency) of the light emitted by the light-emitting unit 71 is set in advance. The light-emitting unit 71 irradiates, for example, visible light. The light-receiving unit 72 receives the light of the wavelength emitted by the light-emitting unit 71.

[0069] In this third modified example, the portion of the water pipe 30 where the optical sensor 70 is provided is the transparent pipe section 34. The transparent pipe section 34 is transparent to the light of the wavelength emitted by the light-emitting section 71, that is, it is made of a material that has the property of transmitting light of the wavelength emitted by the light-emitting section 71. The light-emitting section 71 irradiates light onto the water in the outflow water pipe 31 through the transparent pipe section 34. The light-receiving section 72 irradiates the light irradiated from the light-emitting section 71 through the transparent pipe section 34. Note that the transparent pipe section 34 may have transparent window sections only at the portions facing the light-emitting section 71 and the light-receiving section 72. Note that if the light-emitting section 71 and the light-receiving section 72 are provided inside the water pipe 30, the transparent pipe section 34 may be omitted.

[0070] When there are no air bubbles in the water in the outflow water pipe 31, the light emitted from the light-emitting unit 71 reaches the light-receiving unit 72 with almost no scattering. On the other hand, when there are air bubbles in the water in the outflow water pipe 31, the light emitted from the light-emitting unit 71 is scattered by the air bubbles. Therefore, when there are air bubbles in the water in the outflow water pipe 31, the intensity of the light received by the light-receiving unit 72 is lower than when there are no air bubbles. The presence or absence of air bubbles in the water in the outflow water pipe 31 can be detected based on the light-receiving unit 72's received light intensity. The optical sensor 70 is a bubble detection means that detects air bubbles in the water in the outflow water pipe 31 between the water heat exchanger 17 and the air vent valve 40.

[0071] In this third modified example, refrigerant intrusion detection unit 120 detects the intrusion of refrigerant into water pipe 30 based on the detection result of optical sensor 70. That is, when the light receiving intensity of light receiving unit 72 of optical sensor 70 is equal to or less than a preset reference light receiving intensity, refrigerant intrusion detection unit 120 detects that air bubbles are present in the water inside water pipe 30 and that refrigerant has intruded into water pipe 30. This third modified example also makes it possible to detect the intrusion of refrigerant into water pipe 30 without being affected by fluctuations in water temperature and water pressure in the water circuit.

[0072] FIG. 10 is a diagram showing an example of a configuration for realizing the functions of the control device 100 in this embodiment. The functions of the control device 100 are realized by, for example, a processing circuit. The processing circuit may include a processor 101 and a memory 102. The processing circuit may be dedicated hardware 103. A part of the processing circuit may be formed as dedicated hardware 103, and the processing circuit may further include a processor 101 and a memory 102. In the example shown in the figure, a part of the processing circuit is formed as dedicated hardware 103. Furthermore, in the example shown in the figure, the processing circuit further includes a processor 101 and a memory 102.

[0073] The processing circuitry, part of which is at least one dedicated hardware 103, may be, for example, a single circuit, a multiple circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof. If the processing circuitry comprises at least one processor 101 and at least one memory 102, the functionality of the control device 100 may be realized by software, firmware, or a combination of software and firmware.

[0074] The software and firmware are written as programs and stored in memory 102. Processor 101 realizes the functions of each unit by reading and executing the programs stored in memory 102. Processor 101 is also called a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. Memory 102 may include, for example, non-volatile or volatile semiconductor memory such as RAM, ROM, flash memory, EPROM, and EEPROM, or a magnetic disk, flexible disk, optical disk, compact disk, minidisk, DVD, etc.

[0075] In this way, the processing circuit of the control device 100 can realize each function of the control device 100 by hardware, software, firmware, or a combination of these. When the processing circuit of the control device 100 includes at least the processor 101 and the memory 102, the processor 101 executes a program stored in the memory 102 in the control device 100, and the hardware and software of the control device 100 work together to realize the functions of each unit of the control device 100. Note that the heat pump device is not limited to a configuration in which the operation is controlled by a single control device 100. The operation of the heat pump device may be controlled by cooperation between multiple devices. [Explanation of symbols]

[0076] 1 outdoor 2 indoors 10 Outdoor unit 11 Refrigerant piping 12 Compressor 13 Four-way valve 14 Outdoor heat exchanger 15 Outdoor fan 16 Expansion valve 17 Water heat exchanger 18 Pump 20 Indoor unit 21 Indoor heat exchanger 22 Indoor fan 30 Water piping 31 Outgoing water piping 32 Return water piping 33 Pressure valve 34 Transparent piping section 40 Air vent valve 50 flow meter 51 1st flow meter 52 2nd flow meter 60 Ultrasonic Sensor 61 Ultrasonic transmitter 62 Ultrasonic receiver 70 Optical Sensor 71 Light-emitting part 72 Light receiving part 100 control device 101 processors 102 memory 103 Dedicated Hardware 110 control section 120 Refrigerant intrusion detection unit

Claims

1. a first heat exchanger that exchanges heat between the refrigerant and air; a second heat exchanger that exchanges heat between the refrigerant and water; a third heat exchanger for exchanging heat between the water and air; a refrigerant pipe annularly connecting the first heat exchanger and the second heat exchanger and containing the refrigerant; a water pipe annularly connecting the second heat exchanger and the third heat exchanger and containing the water; a pump that circulates water in the water pipe; an air vent valve capable of discharging gas from the water pipe to the outside, The water piping includes a forward water piping through which the water flows from the second heat exchanger to the third heat exchanger, and a return water piping through which the water flows from the third heat exchanger to the second heat exchanger, The air vent valve is provided in the outflow water pipe, a flow meter provided in the outflow water piping between the second heat exchanger and the air vent valve, the flow meter detecting a flow rate of water in the outflow water piping; The heat pump device further includes a refrigerant intrusion detection unit that detects intrusion of the refrigerant into the water pipe based on a detection result of the flow meter.

2. Further, a control unit is provided to control the operation of the pump. The heat pump apparatus according to claim 1 , wherein the control unit stops the pump when the refrigerant intrusion detection unit detects the intrusion of the refrigerant into the water pipe.

3. The heat pump device of claim 2, wherein the length of the outward water piping from the flow meter to the air vent valve is equal to or greater than the product of the time from when the refrigerant that has entered the water piping passes through the flow meter to when the control unit stops the pump and the maximum flow velocity of the water in the water piping when the pump is operating.

4. a first heat exchanger that exchanges heat between the refrigerant and air; a second heat exchanger that exchanges heat between the refrigerant and water; a third heat exchanger for exchanging heat between the water and air; a refrigerant pipe annularly connecting the first heat exchanger and the second heat exchanger and containing the refrigerant; a water pipe annularly connecting the second heat exchanger and the third heat exchanger and containing the water; a pump that circulates water in the water pipe; an air vent valve capable of discharging gas from the water pipe to the outside, The water piping includes a forward water piping through which the water flows from the second heat exchanger to the third heat exchanger, and a return water piping through which the water flows from the third heat exchanger to the second heat exchanger, The air vent valve is provided in the outflow water pipe, The heat pump apparatus further comprises a bubble detection means for detecting air bubbles in the water in the outflow water pipe between the second heat exchanger and the air vent valve.

5. The bubble detection means an ultrasonic wave irradiation unit that irradiates ultrasonic waves to the water in the outflow water pipe; The heat pump device according to claim 4 , further comprising: an ultrasonic wave receiving unit that receives the ultrasonic waves.

6. The bubble detection means a light irradiation unit that irradiates light onto the water in the outflow water piping; The heat pump device according to claim 4 , further comprising: a light receiving section that receives the light.

7. a part of the outgoing water piping is a transparent piping portion that is transparent to the light, The heat pump apparatus according to claim 6 , wherein the light irradiating section irradiates the light onto the water in the outflow water pipe through the transparent pipe section.

8. Further, a control unit is provided to control the operation of the pump. The heat pump apparatus according to any one of claims 4 to 7, wherein the control unit stops the pump when the bubble detection means detects bubbles in the water in the outflow water pipe.

9. The heat pump device described in claim 8, wherein the length of the outward water piping from the bubble detection means to the air vent valve is greater than or equal to the product of the time from when the refrigerant that has entered the water piping passes through the bubble detection means to when the control unit stops the pump and the maximum flow velocity of the water in the water piping when the pump is operating.

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