Control device for outdoor unit, outdoor unit, heat pump system, and outdoor unit control method

Abstract

The present invention provides an outdoor unit control device that can minimize refrigerant leakage even in heat pump systems equipped with a water exchanger. [Solution] An outdoor unit control device for controlling an outdoor unit 1 comprising a compressor 17, an outdoor heat exchanger 30, a water heat exchanger 19, an expansion valve 45, a four-way valve 49, and a water circuit W that sends water that has undergone heat exchange in the water heat exchanger 19 to the indoor unit, has a cooling mode in which the four-way valve 49 is switched to operate the water heat exchanger 19 as an evaporator and the outdoor heat exchanger 30 as a condenser, and a heating mode in which the four-way valve 49 is switched to operate the water heat exchanger 19 as a condenser and the outdoor heat exchanger 30 as an evaporator, and when a leak of refrigerant into the water circuit W is detected, the device switches to the cooling mode and completely closes the expansion valve 45.

Description

Technical Field

[0006] , , , ,

[0007] , ,

[0001] The present disclosure relates to a control device for an outdoor unit, an outdoor unit, a heat pump device, and a method for controlling an outdoor unit.

Background Art

[0002] R290, which is propane, a natural refrigerant, is being promoted for use as a refrigerant in heat pump devices because of its low GWP (global warming potential). However, R290 is classified as a highly flammable refrigerant and there is a risk of ignition if it leaks.

[0003] Patent Document 1 discloses that when a refrigerant leak is detected, the user is notified and the refrigerant is recovered in the outdoor unit. The air conditioner of Patent Document 1 is a direct expansion type (direct expansion method) in which the refrigerant is led to the indoor unit for indoor air conditioning.

[0004] <00000,15>For the above direct expansion type, there is known a heat pump device in which a refrigerant circuit is formed in an outdoor unit and a water heat exchanger for exchanging heat between the refrigerant and water (heat medium) is provided in this refrigerant circuit (see Patent Document 2). The water heat-exchanged by the water heat exchanger is sent to the indoor unit, which is the heat utilization destination, via a water circuit.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] In Patent Document 1, since it is a direct expansion type, when the refrigerant leaks indoors, the refrigerant is recovered from the indoor unit to the outdoor unit.

[0007] In contrast, the heat pump device described in Patent Document 2 separates the refrigerant circuit and the water circuit using a water heat exchanger, and is not configured to allow refrigerant to flow to the indoor unit. Furthermore, the water circuit connecting the water heat exchanger and the indoor unit is often equipped with a gas separator to separate and discharge any gas mixed in with the water. This prevents refrigerant from being guided to the indoor unit via the water circuit even if it leaks into the water.

[0008] However, even if a gas separator is installed, there is a risk that refrigerant may leak into the water due to some malfunction and be guided to the indoor unit. Therefore, even with a heat pump system equipped with a water heat exchanger, it is necessary to minimize refrigerant leakage into the water circuit.

[0009] This disclosure has been made in view of these circumstances and aims to provide an outdoor unit control device, an outdoor unit, a heat pump system, and an outdoor unit control method that can minimize refrigerant leakage into the heat transfer medium circuit even in a heat pump system equipped with a heat transfer medium heat exchanger. [Means for solving the problem]

[0010] A control device for an outdoor unit according to one aspect of the present disclosure includes: a compressor for compressing a refrigerant; a refrigerant circuit through which the refrigerant discharged from the compressor circulates; an outdoor heat exchanger provided in the refrigerant circuit for exchanging heat between the refrigerant and outside air; a heat exchanger provided in the refrigerant circuit for exchanging heat between the refrigerant and a liquid heat transfer medium; an expansion valve provided in the refrigerant circuit for expanding the refrigerant; a switching valve for switching the flow of the refrigerant discharged from the compressor to the outdoor heat exchanger or the heat exchanger; and heat exchange in the heat exchanger. An outdoor unit control device for controlling an outdoor unit comprising a heat transfer circuit that sends a heated heat transfer medium to a heat utilization destination, having a cooling mode in which the switching valve is switched to operate the heat transfer medium heat exchanger as an evaporator and the outdoor heat exchanger as a condenser, and a heating mode in which the switching valve is switched to operate the heat transfer medium heat exchanger as a condenser and the outdoor heat exchanger as an evaporator, wherein when a leak of refrigerant into the heat transfer circuit is detected, the device switches to the cooling mode and completely closes the expansion valve.

[0011] An outdoor unit according to one aspect of the present disclosure includes a compressor for compressing a refrigerant, a refrigerant circuit through which the refrigerant discharged from the compressor circulates, an outdoor heat exchanger provided in the refrigerant circuit for exchanging heat between the refrigerant and outside air, a heat exchanger provided in the refrigerant circuit for exchanging heat between the refrigerant and a liquid heat transfer medium, an expansion valve provided in the refrigerant circuit for expanding the refrigerant, a switching valve for switching the flow of the refrigerant discharged from the compressor to the outdoor heat exchanger or the heat exchanger, a heat transfer medium circuit for sending the heat transfer medium that has been heat-exchanged in the heat exchanger to a heat utilization destination, and the above-mentioned control device for the outdoor unit.

[0012] A heat pump system according to one aspect of this disclosure comprises the above-mentioned outdoor unit and a heat utilization unit connected to the outdoor unit.

[0013] An outdoor unit control method according to one aspect of the present disclosure includes: a compressor for compressing a refrigerant; a refrigerant circuit through which the refrigerant discharged from the compressor circulates; an outdoor heat exchanger provided in the refrigerant circuit for heat exchange between the refrigerant and outside air; a heat exchanger provided in the refrigerant circuit for heat exchange between the refrigerant and a liquid heat transfer medium; an expansion valve provided in the refrigerant circuit for expanding the refrigerant; a switching valve for switching the flow of the refrigerant discharged from the compressor to the outdoor heat exchanger or the heat exchanger; and heat exchange in the heat exchanger. An outdoor unit control method for controlling an outdoor unit comprising a heat transfer circuit that sends a heated heat transfer medium to a heat utilization destination, comprising: a cooling mode in which the switching valve is switched to operate the heat transfer medium heat exchanger as an evaporator and the outdoor heat exchanger as a condenser; and a heating mode in which the switching valve is switched to operate the heat transfer medium heat exchanger as a condenser and the outdoor heat exchanger as an evaporator, wherein when a leak of refrigerant into the heat transfer circuit is detected, the system is switched to the cooling mode and the expansion valve is fully closed. [Effects of the Invention]

[0014] Even in heat pump systems equipped with a heat transfer medium heat exchanger, refrigerant leakage into the heat transfer medium circuit can be minimized. [Brief explanation of the drawing]

[0015] [Figure 1] This is a perspective view showing an outdoor unit according to one embodiment of the present disclosure. [Figure 2] Figure 1 is a vertical cross-sectional view of the outdoor unit. [Figure 3] This is a schematic diagram of the refrigeration cycle of a heat pump system. [Figure 4] This is a flowchart illustrating refrigerant leakage suppression control. [Modes for carrying out the invention]

[0016] An embodiment relating to this disclosure will be described below with reference to the drawings. FIG. 1 shows an outdoor unit 1 used in a heat pump device. The outdoor unit 1 in FIG. 1 is shown in a state where the panel of the machine room 7 is removed.

[0017] The outdoor unit 1 is connected to an indoor unit (heat utilization unit) via a water circuit using a water pipe (heat medium pipe) not shown in the figure. Water circulates between the outdoor unit 1 and the indoor unit through the water pipe. Thereby, the warm or cold heat generated in the outdoor unit 1 is sent to the indoor unit through the water pipe to provide warm or cold heat indoors.

[0018] As shown in FIG. 1, the outdoor unit 1 includes a substantially rectangular parallelepiped housing 3. The bottom of the housing 3 is a sheet metal base 4. The base 4 includes base legs 4a provided on both sides along the longitudinal direction, and a substantially flat plate portion 4b provided between the upper ends of the base legs 4a on both sides. The flat plate portion 4b extends substantially horizontally, and various devices are installed above it. The flat plate portion 4b has concavities and convexities formed by press working.

[0019] As shown in FIG. 1, inside the housing 3, above the base 4, there are provided a fan chamber 5 and a machine room 7 partitioned left and right by a partition wall 9.

[0020] The fan chamber 5 is located on the left side in FIG. 1. Inside the fan chamber 5, an outdoor fan and an outdoor heat exchanger 30 (see FIG. 2) not shown in the figure are provided. The outdoor heat exchanger 30 has a shape bent in an L shape so as to form the side and back surfaces of the fan chamber 5. The outside air taken in by the outdoor fan exchanges heat with the refrigerant flowing through the outdoor heat exchanger 30. The outside air after heat exchange with the refrigerant is discharged to the outside from the fan opening 11.

[0021] The machine room 7 is located on the right side in FIG. 1. In the machine room 7, a sub-base 13 in the form of a plate-like body is provided on the base 4 (specifically, the flat plate portion 4b). The sub-base 13 is rectangular in plan view and has a size that covers substantially the entire area below the machine room 7. However, a predetermined gap is formed between the four sides of the sub-base 13 and the opposing side walls and partition wall 9 of the housing 3.

[0022] As shown in Fig. 2, between the base 4 and the sub-base 13, a plurality of sub-base support members 15 provided with vibration isolators are provided. The sub-base 13 is supported by the base 4 by each sub-base support member 15.

[0023] As shown in Fig. 1, in the machine room 7, above the sub-base 13, a compressor 17, a water heat exchanger 19, a gas separator 21, a control box 23, etc. are provided.

[0024] The compressor 17 is, for example, a rotary compressor and compresses a refrigerant having flammability such as R290. As shown in Fig. 2, at the lower part of the compressor 17, a compressor leg 17a provided with a vibration isolator is provided. The compressor leg 17a is attached onto the sub-base 13. The vibration of the compressor 17 transmitted to the sub-base 13 is mitigated by the compressor leg 17a provided with a vibration isolator. The sub-base 13 does not have unnecessary through-holes except for holes for attaching devices such as the sub-base support members 15 and the compressor leg 17a. Therefore, basically, there are no through-holes in the sub-base 13 after attaching the devices.

[0025] The refrigerant compressed by the compressor 17 is sent to the water heat exchanger 19 or the outdoor heat exchanger 30 via a four-way valve (not shown). A refrigerant circuit in which the refrigerant circulates is formed by the compressor 17, the four-way valve (not shown), the water heat exchanger 19, the outdoor heat exchanger 30, an expansion valve (not shown), and the refrigerant pipes connecting them.

[0026] The water heat exchanger 19 exchanges heat between the refrigerant and water (heat medium). The water that has exchanged heat with the refrigerant is separated from gas (such as air and refrigerant) by the gas separator 21 and then guided to the indoor unit through the water supply pipe 25. The water after exchanging heat with the indoor air in the indoor unit is returned to the water heat exchanger 19 through the water return pipe 26. Thereby, the water circulates between the water heat exchanger 19 and the indoor unit through the water circuit. <0000​A water connection pipe 46 is connected to the side of the gas separator to guide water from the water heat exchanger 19, and a water supply pipe 25 is connected to the bottom of the gas separator 21. Water flowing in through the water connection pipe 46 is separated into gas and liquid within the gas separator 21, and the treated water is discharged into the water supply pipe 25.

[0028] The gas separator 21 has an ejection port 21a that protrudes upward from the top of the gas separator 21 to eject the separated gas (such as refrigerant or air). The ejection port 21a is equipped with a check valve, and when the separated gas exceeds a predetermined pressure, the check valve opens and the gas is ejected to the outside. The direction of gas ejection is horizontal, as indicated by arrow A1.

[0029] A water relief outlet 21b is provided on the side of the gas separator, which has a pressure relief valve that opens when the pressure of the incoming water exceeds a predetermined value. A water discharge pipe that leads water to the outside of the outdoor unit 1 is connected to the water relief outlet 21b, although it is not shown in the figure.

[0030] The control box 23 has a sealed structure that houses electrical equipment such as capacitors and coils inside. Furthermore, the control box 23 is equipped with a terminal block that has electrical terminals for receiving power from an external source.

[0031] Figure 2 also shows the same compressor 17, water heat exchanger 19, and gas separator 21 as in Figure 1. An accumulator 28 is shown to the side of the compressor 17. An outdoor heat exchanger 30 is also shown on the right side of Figure 2. The outdoor heat exchanger 30 is installed in the fan room 5 (see Figure 1) as described above.

[0032] Although not shown in the diagram, the base 4 is provided with a drain hole in a position corresponding to the fan chamber 5. The drain hole is, for example, circular in shape, with a diameter of, for example, 20 mm. The drain hole is located on the lower surface, which is the lowest position on the flat plate portion 4b of the base 4. The lower surface extends continuously across the machine chamber 7. The lower surface is inclined so that the drain hole faces downwards. This allows condensed water to adhere to equipment such as the outdoor heat exchanger 30 inside the housing 3 and flow downwards, so that the drain water can be discharged to the outside through the drain hole via the lower surface.

[0033] As shown in Figure 2, the base 4 is provided with a refrigerant discharge port 34 at a position corresponding to the machine room 7. Through the refrigerant discharge port 34, the refrigerant released into the machine room 7 is discharged to the outside (atmosphere).

[0034] The refrigerant discharge hole 34 is, for example, circular in shape, with a diameter of 30 mm or more, preferably about 60 mm. In other words, the area of ​​the refrigerant discharge hole 34 is larger than the area of ​​the drain hole.

[0035] As shown in Figure 2, the refrigerant discharge hole 34 is provided with a resin mesh 40 to prevent insects and other small animals from entering the inside of the housing 3 from the outside.

[0036] A refrigerant detection sensor 42 is installed below the machine room 7. The refrigerant detection sensor 42 detects refrigerant leaking into the machine room 7. The detection output of the refrigerant detection sensor 42 is transmitted to a control unit (not shown). The control unit determines that a refrigerant leak has occurred when the concentration of refrigerant detected by the refrigerant detection sensor 42 exceeds a predetermined value. The refrigerant detection sensor 42 is installed below the gas separator 21.

[0037] The control unit is an outdoor unit control device that controls each component of the outdoor unit 1, and is provided, for example, in the control box 23. The control unit consists of, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and a computer-readable storage medium. A series of processes for realizing various functions are stored in the storage medium in the form of a program, for example, and the CPU reads this program into the RAM and performs information processing and calculations to realize the various functions. The program may be pre-installed in ROM or other storage media, provided in a state where it is stored in a computer-readable storage medium, or distributed via wired or wireless communication means. Computer-readable storage media include magnetic disks, magneto-optical disks, CD-ROMs, DVD-ROMs, semiconductor memory, etc.

[0038] Figure 3 shows a schematic configuration of the refrigeration cycle of a heat pump system using the outdoor unit 1 with the above configuration. Note that the same components shown in Figures 1 and 2 are indicated by the same reference numerals.

[0039] The refrigerant circuit C, which constitutes the refrigeration cycle, includes a compressor 17, a water heat exchanger 19, an expansion valve 45, and an outdoor heat exchanger 30. A four-way valve (switching valve) 49 is provided downstream of the discharge pipe 47 connected to the discharge port of the compressor 17. An accumulator 28 and a suction pressure sensor 29 are provided upstream of the suction port of the compressor 17. The output of the suction pressure sensor 29 is transmitted to the control unit.

[0040] A liquid refrigerant piping 51 between the expansion valve 45 and the water heat exchanger 19 has a liquid pipe temperature sensor 53 installed in close proximity to the water heat exchanger 19. The output of the liquid pipe temperature sensor 53 is transmitted to the control unit.

[0041] A water circuit W is connected to the water heat exchanger 19. The water circuit W includes an indoor unit (heat utilization unit) (not shown), a gas separator 21, and a water pump (heat transfer medium pump) 55. The gas separator 21 is located on the water outlet side of the water heat exchanger 19, and the water pump 55 is located on the water inlet side of the water heat exchanger 19. A water inlet temperature sensor 57 is located on the water inlet side of the water heat exchanger 19, and a water outlet temperature sensor 59 is located on the water outlet side of the water heat exchanger 19. The output of each temperature sensor 57 is transmitted to the control unit.

[0042] The heat pump system shown in Figure 3 operates as follows. <Cooling mode> In cooling mode, the control unit switches the four-way valve 49 according to its command, and it operates as shown by the solid arrow. The high-pressure refrigerant discharged from the compressor 17 passes through the four-way valve and is sent to the outdoor heat exchanger 30. In the outdoor heat exchanger 30, the refrigerant condenses as it releases heat to the outside air. The condensed and liquefied refrigerant is sent to the expansion valve 45, where the expansion valve 45 reduces the pressure of the refrigerant to a predetermined level. The opening degree of the expansion valve 45 is controlled by the control unit.

[0043] The refrigerant, depressurized by the expansion valve 45, is sent to the water heat exchanger 19, where it absorbs heat from the water flowing through the water heat exchanger 19 and is evaporated. The refrigerant evaporated in the water heat exchanger 19 is then guided through the four-way valve 49 and the accumulator 28 to the suction side of the compressor 17.

[0044] The chilled water generated in the water heat exchanger 19 by the latent heat of vaporization of the refrigerant flows to the gas separator 21 via the water pump 55. In the gas separator 21, the refrigerant and other gases such as air contained in the chilled water are separated, and the chilled water after separation is sent to the indoor unit. After the indoor unit has finished cooling, the chilled water is returned to the water pump 55 and guided back to the water heat exchanger 19.

[0045] <Heating mode> In heating mode, the control unit switches the four-way valve 49 according to its command, and it operates as shown by the dashed arrow. The high-pressure refrigerant discharged from the compressor 17 passes through the four-way valve and is sent to the water heat exchanger 19. In the water heat exchanger 19, heat is released to the water supplied from the water circuit W, heating the water and turning it into hot water.

[0046] The refrigerant, which has condensed and liquefied in the water heat exchanger 19, is sent to the expansion valve 45, where the refrigerant is reduced to a predetermined pressure. The opening degree of the expansion valve 45 is controlled by the control unit.

[0047] The refrigerant, depressurized by the expansion valve 45, is sent to the outdoor heat exchanger 30, where it absorbs heat from the outside air and evaporates. The refrigerant evaporated in the outdoor heat exchanger 30 is then guided through the four-way valve 49 and the accumulator 28 to the suction side of the compressor 17.

[0048] The hot water generated in the water heat exchanger 19, heated by the latent heat of condensation of the refrigerant, flows to the gas separator 21 via the water pump 55. In the gas separator 21, gases such as refrigerant and air contained in the hot water are separated, and the separated hot water is sent to the indoor unit. After heating in the indoor unit, the hot water is returned to the water pump 55 and then guided back to the water heat exchanger 19.

[0049] <Refrigerant Leakage Suppression Control> Next, we will explain the operation when refrigerant leaks into the water circuit W. The gas separator 21 separates gases such as refrigerant and air contained in the water introduced from the water heat exchanger 19. If a large amount of gas leaks into the water due to some malfunction, the pressure of the gas separated by the gas separator 21 increases, and the gas is ejected into the outdoor unit 1 from the ejection port 21a (see Figure 2). The refrigerant contained in the ejected gas has a higher specific gravity than air, so it flows downward due to its own weight, passes the side of the sub-base 13 to the base 4, and is discharged to the outside from the refrigerant discharge hole 34 formed in the base 4. As the refrigerant flows downward inside the outdoor unit 1, it reaches the refrigerant detection sensor 42, which detects the refrigerant concentration and transmits it to the control unit. The control unit determines that there is a refrigerant leak when the refrigerant concentration exceeds a predetermined value and performs the following refrigerant leak suppression control.

[0050] As shown in Figure 4, when refrigerant leakage into the water flowing through the water circuit W is detected (step S1), the mode is changed to cooling mode (step S2). If it is in heating mode, the four-way valve 49 is switched to change to cooling mode, and if it is in cooling mode, the cooling mode is continued.

[0051] Then, the expansion valve 45 is completely closed (step S3). As a result, the refrigerant in the water heat exchanger 19 is drawn into the compressor 17 and recovered in the outdoor heat exchanger 30, and the refrigerant pressure in the water heat exchanger 19 decreases.

[0052] The refrigerant pressure in the water heat exchanger 19 is controlled to be less than or equal to the water pressure in the water heat exchanger 19 (step S4). Specifically, the refrigerant pressure in the water heat exchanger 19 is calculated based on the measurement value of the suction pressure sensor 29 (see Figure 3), and the rotational speed of the compressor 17 is controlled and / or the compressor 17 is started and stopped to keep it less than or equal to the water pressure flowing through the water circuit W (the set value of the water pressure, for example, 0.1 MPa (gauge pressure)). However, the refrigerant pressure is controlled so that it does not fall below atmospheric pressure so that air does not enter the refrigerant circuit C. Alternatively, a pressure sensor may be installed in the water circuit W and the control may be performed using the measured value of the water pressure.

[0053] After the refrigerant pressure in the water heat exchanger 19 reaches the desired value, the expansion valve 45 may be opened from the fully closed position to maintain that refrigerant pressure, and the degree of opening may be adjusted as appropriate.

[0054] Next, the discharge flow rate of the water pump 55 is reduced (step S5). This reduces the amount of refrigerant supplied to the indoor unit. In addition, reducing the water flow rate improves the refrigerant separation efficiency of the gas separator 21. However, the water pump 55 is controlled not to stop in order to prevent the water in the water heat exchanger 19 from freezing.

[0055] Next, the refrigerant temperature of the water heat exchanger 19 is calculated based on the liquid pipe temperature sensor 53, and freeze prevention control is performed in the water heat exchanger 19 to prevent the water from freezing (step S6). Specifically, the rotational speed of the compressor 17 is controlled, and / or the compressor 17 is started and stopped to control it.

[0056] Then, after a predetermined time has elapsed, the operation of the outdoor unit 1 is stopped (step S7), the user is notified (step S8), and the refrigerant leakage suppression control is terminated.

[0057] The effects and advantages of this embodiment, as described above, are as follows. If a refrigerant leak into the water circuit W is detected, it is highly likely that the refrigerant leaked into the water in the water heat exchanger 19. Therefore, by setting the system to cooling mode and completely closing the expansion valve 45, the refrigerant pressure in the water heat exchanger 19, which is acting as an evaporator, is reduced. This minimizes the leakage of refrigerant into the water in the water heat exchanger 19.

[0058] The refrigerant separated from the water by the gas separator 21 is detected by the refrigerant detection sensor 42, and the leakage of refrigerant into the water circuit W is determined. This allows for accurate detection of refrigerant leakage into the water.

[0059] Since the refrigerant pressure in the water heat exchanger 19 is controlled to be less than or equal to the water pressure, mixing of the refrigerant with the water can be avoided. While it is preferable to set the target value of the refrigerant pressure lower than the water pressure, it may also be controlled to remain within a predetermined differential pressure range.

[0060] If the expansion valve 45 is fully closed and the cooling mode is operated, the pressure in the water heat exchanger 19 will drop, causing the circulating water to freeze, which may lead to damage in some cases. Therefore, the temperature of the water heat exchanger 19 is controlled to prevent the water from freezing.

[0061] When a refrigerant leak into the water circuit W is detected, the discharge flow rate of the water pump 55 that circulates the water through the water circuit W is reduced. This reduces the amount of refrigerant supplied to the indoor unit. Furthermore, reducing the water flow rate improves the refrigerant separation efficiency in the gas separator 21.

[0062] The outdoor unit control device, outdoor unit, heat pump device, and outdoor unit control method described in each embodiment above can be understood, for example, as follows.

[0063] A control device for an outdoor unit according to a first aspect of this disclosure includes a compressor (17) for compressing a refrigerant, a refrigerant circuit (C) through which the refrigerant discharged from the compressor circulates, an outdoor heat exchanger (30) provided in the refrigerant circuit for exchanging heat between the refrigerant and outside air, a heat transfer medium heat exchanger (19) provided in the refrigerant circuit for exchanging heat between the refrigerant and a liquid heat transfer medium, an expansion valve (45) provided in the refrigerant circuit for expanding the refrigerant, a switching valve (49) for switching the flow of the refrigerant discharged from the compressor to the outdoor heat exchanger or the heat transfer medium heat exchanger, and the heat transfer medium An outdoor unit control device for controlling an outdoor unit (1) which includes a heat transfer medium circuit (W) that sends a heat transfer medium that has been heat-exchanged in a heat exchanger to a heat utilization destination, has a cooling mode in which the switching valve is switched to operate the heat transfer medium heat exchanger as an evaporator and the outdoor heat exchanger as a condenser, and a heating mode in which the switching valve is switched to operate the heat transfer medium heat exchanger as a condenser and the outdoor heat exchanger as an evaporator, and when a leak of refrigerant into the heat transfer medium circuit is detected, the device switches to the cooling mode and closes the expansion valve completely.

[0064] If refrigerant leakage into the heat transfer circuit is detected, it is highly likely that refrigerant has leaked into the heat transfer medium in the heat transfer heat exchanger. Therefore, by switching to cooling mode and completely closing the expansion valve, the refrigerant pressure in the heat transfer heat exchanger, which is acting as the evaporator, is reduced. This minimizes refrigerant leakage into the heat transfer medium in the heat transfer heat exchanger.

[0065] In the first embodiment, the outdoor unit control device according to a second aspect of the present disclosure includes a gas separator (21) provided in the heat transfer medium circuit for separating gaseous refrigerant from the heat transfer medium, and a refrigerant detection sensor (42) capable of detecting the refrigerant separated from the gas separator, wherein the refrigerant detection sensor detects leakage of refrigerant into the heat transfer medium circuit.

[0066] The gas separator separates the refrigerant that has leaked into the heat transfer medium. The refrigerant separated by the gas separator is detected by a refrigerant detection sensor, and the leakage of refrigerant into the heat transfer medium circuit is determined. This allows for accurate determination of refrigerant leakage into the heat transfer medium.

[0067] In the third aspect of this disclosure, the control device for an outdoor unit controls the refrigerant pressure of the heat exchanger to approach the heat transfer fluid pressure of the heat exchanger, in the first or second aspect.

[0068] By controlling the refrigerant pressure in the heat exchanger to approach the heat transfer fluid pressure, the pressure difference between the heat transfer fluid and the refrigerant is reduced. This reduces the amount of refrigerant mixed into the heat transfer fluid. The target value of the refrigerant pressure is preferably small relative to the heat transfer fluid pressure, but it may also be controlled to maintain a differential pressure within a predetermined range. Refrigerant pressure can be controlled, for example, by controlling the compressor's rotational speed or by starting and stopping it. After the refrigerant pressure in the heat exchanger reaches the desired value, the opening of the expansion valve may be adjusted to maintain that refrigerant pressure.

[0069] In any of the first to third embodiments, the control device for an outdoor unit according to the fourth aspect of this disclosure controls the temperature of the heat exchanger so that the heat transfer medium flowing through the heat exchanger does not freeze.

[0070] If the expansion valve is fully closed and the cooling mode is operated, the pressure in the heat transfer fluid heat exchanger will drop, causing the circulating heat transfer fluid to freeze, which may lead to damage in some cases. Therefore, we decided to control the temperature of the heat transfer fluid heat exchanger to prevent the heat transfer fluid from freezing. Temperature control of the heat transfer fluid heat exchanger is performed, for example, by controlling the rotational speed and starting / stopping the compressor.

[0071] In any of the first to fourth embodiments of the present disclosure, the control device for an outdoor unit reduces the discharge flow rate of the heat transfer pump (55) that circulates the heat transfer medium through the heat transfer circuit when it detects a leak of refrigerant into the heat transfer circuit.

[0072] When a refrigerant leak into the heat transfer circuit is detected, the discharge flow rate of the heat transfer pump that circulates the heat transfer fluid through the circuit is reduced. This reduces the amount of refrigerant supplied to the heat utilization site. Furthermore, if a gas separator is provided in the heat transfer circuit, reducing the flow rate of the heat transfer fluid can improve the refrigerant separation efficiency. Furthermore, the heat transfer fluid pump will ensure a discharge flow rate above a predetermined level to prevent the heat transfer fluid from freezing in the heat transfer fluid heat exchanger. Therefore, the heat transfer fluid pump will be controlled to prevent it from stopping.

[0073] An outdoor unit according to a first aspect of this disclosure includes a compressor for compressing a refrigerant, a refrigerant circuit through which the refrigerant discharged from the compressor circulates, an outdoor heat exchanger provided in the refrigerant circuit for exchanging heat between the refrigerant and outside air, a heat exchanger provided in the refrigerant circuit for exchanging heat between the refrigerant and a liquid heat transfer medium, an expansion valve provided in the refrigerant circuit for expanding the refrigerant, a switching valve for switching the refrigerant discharged from the compressor to flow to the outdoor heat exchanger or the heat exchanger, a heat transfer medium circuit for sending the heat transfer medium that has been heat-exchanged in the heat exchanger to a heat utilization destination, and an outdoor unit control device as described in any of the above.

[0074] A heat pump system according to a first aspect of this disclosure comprises the above-mentioned outdoor unit and a heat utilization unit connected to the outdoor unit.

[0075] An outdoor unit control method according to a first aspect of this disclosure includes: a compressor for compressing a refrigerant; a refrigerant circuit through which the refrigerant discharged from the compressor circulates; an outdoor heat exchanger provided in the refrigerant circuit for exchanging heat between the refrigerant and outside air; a heat exchanger provided in the refrigerant circuit for exchanging heat between the refrigerant and a liquid heat transfer medium; an expansion valve provided in the refrigerant circuit for expanding the refrigerant; a switching valve for switching the flow of the refrigerant discharged from the compressor to the outdoor heat exchanger or the heat exchanger; and heat exchange in the heat exchanger. An outdoor unit control method for controlling an outdoor unit comprising a heat transfer circuit that sends a heated heat transfer medium to a heat utilization destination, comprising: a cooling mode in which the switching valve is switched to operate the heat transfer medium heat exchanger as an evaporator and the outdoor heat exchanger as a condenser; and a heating mode in which the switching valve is switched to operate the heat transfer medium heat exchanger as a condenser and the outdoor heat exchanger as an evaporator, wherein when a leak of refrigerant into the heat transfer circuit is detected, the system is switched to the cooling mode and the expansion valve is fully closed. [Explanation of Symbols]

[0076] 1 Outdoor unit 3 cabinets 4 bases 4a Base Legs 4b Flat plate part 5. Fan Room 7 Machine room 9 Partition wall 11 Fan opening 13 Sub-base 15 Subbase support member 17 Compressor 17a Compressor legs 19 Water heat exchanger 21 Gas Separator 21a Spout part 21b Water relief outlet 23 Control Box 25 Water supply piping 26 Water return piping 28 Accumulator 29. Suction pressure sensor 30 Outdoor heat exchanger 34 Refrigerant discharge hole 40 mesh 42 Refrigerant detection sensor 45 Expansion valve 47 Discharge pipe 49. Four-way valve (switching valve) 51 Liquid refrigerant piping 53 Liquid tube temperature sensor 55 Water pump (heat transfer pump) 57 Water Inlet Temperature Sensor 59 Water outlet temperature sensor C Refrigerant circuit W Water circuit (heat medium circuit)

Claims

1. A compressor that compresses the refrigerant, A refrigerant circuit through which the refrigerant discharged from the compressor circulates, An outdoor heat exchanger is provided in the refrigerant circuit and exchanges heat between the refrigerant and the outside air, A heat exchanger is provided in the refrigerant circuit and exchanges heat between the refrigerant and a liquid heat transfer medium, An expansion valve is provided in the refrigerant circuit for expanding the refrigerant, A switching valve that switches the refrigerant discharged from the compressor to flow to the outdoor heat exchanger or the heat transfer medium heat exchanger, A heat transfer circuit that sends the heat transfer medium, which has undergone heat exchange in the aforementioned heat transfer heat exchanger, to a heat utilization destination. An outdoor unit control device for controlling an outdoor unit equipped with the following: Switching the aforementioned switching valve to operate the heat transfer fluid heat exchanger as an evaporator and the outdoor heat exchanger as a condenser creates a cooling mode, Switching the aforementioned switching valve, a heating mode is provided in which the heat transfer medium heat exchanger operates as a condenser and the outdoor heat exchanger operates as an evaporator, It has, A control device for an outdoor unit that, upon detecting a refrigerant leak into the heat transfer medium circuit, switches to the cooling mode and completely closes the expansion valve.

2. The outdoor unit is provided in the heat transfer medium circuit and includes a gas separator that separates the gaseous refrigerant from the heat transfer medium, A refrigerant detection sensor capable of detecting the refrigerant separated from the gas separator, Equipped with, The control device for an outdoor unit according to claim 1, wherein the refrigerant detection sensor detects leakage of refrigerant into the heat transfer medium circuit.

3. The control device for an outdoor unit according to claim 1 or 2, wherein the refrigerant pressure of the heat exchanger is controlled to approach the heat transfer fluid pressure of the heat exchanger.

4. The control device for an outdoor unit according to claim 1 or 2, which controls the temperature of the heat transfer medium heat exchanger so that the heat transfer medium flowing through the heat transfer medium heat exchanger does not freeze.

5. The control device for an outdoor unit according to claim 1 or 2, wherein when a leak of refrigerant into the heat transfer circuit is detected, the discharge flow rate of a heat transfer pump that circulates the heat transfer fluid through the heat transfer circuit is reduced.

6. A compressor that compresses the refrigerant, A refrigerant circuit through which the refrigerant discharged from the compressor circulates, An outdoor heat exchanger is provided in the refrigerant circuit and exchanges heat between the refrigerant and the outside air, A heat exchanger is provided in the refrigerant circuit and exchanges heat between the refrigerant and a liquid heat transfer medium, An expansion valve is provided in the refrigerant circuit for expanding the refrigerant, A switching valve that switches the refrigerant discharged from the compressor to flow to the outdoor heat exchanger or the heat transfer medium heat exchanger, A heat transfer circuit that sends the heat transfer medium, which has undergone heat exchange in the aforementioned heat transfer heat exchanger, to a heat utilization destination. An outdoor unit control device according to claim 1 or 2, An outdoor unit equipped with this feature.

7. The outdoor unit according to claim 6, A heat utilization unit connected to the aforementioned outdoor unit, A heat pump device equipped with the following features.

8. A compressor that compresses the refrigerant, A refrigerant circuit through which the refrigerant discharged from the compressor circulates, An outdoor heat exchanger is provided in the refrigerant circuit and exchanges heat between the refrigerant and the outside air, A heat exchanger is provided in the refrigerant circuit and exchanges heat between the refrigerant and a liquid heat transfer medium, An expansion valve is provided in the refrigerant circuit for expanding the refrigerant, A switching valve that switches the refrigerant discharged from the compressor to flow to the outdoor heat exchanger or the heat transfer medium heat exchanger, A heat transfer circuit that sends the heat transfer medium, which has undergone heat exchange in the aforementioned heat transfer heat exchanger, to a heat utilization destination. An outdoor unit control method for controlling an outdoor unit equipped with, Switching the aforementioned switching valve to operate the heat transfer fluid heat exchanger as an evaporator and the outdoor heat exchanger as a condenser creates a cooling mode, Switching the aforementioned switching valve, a heating mode is provided in which the heat transfer medium heat exchanger operates as a condenser and the outdoor heat exchanger operates as an evaporator, It has, An outdoor unit control method that, upon detecting a leak of refrigerant into the heat transfer medium circuit, switches to the cooling mode and completely closes the expansion valve.

Images