Heat pump system and controller for controlling operation of the heat pump system

Abstract

Provided is a heat pump system (100) having a compressor (210), a liquid-side on-off valve (420), a gas-side on-off valve (460), and a controller (600). The controller is configured to execute a refrigerant recovery operation for recovering refrigerant from a utilization-side pipe section (102) to a heat-source-side pipe section (101) by operating the compressor while the liquid-side on-off valve is closed and the gas-side on-off valve is open, and control the system such that the gas-side on-off valve starts to close (S2100) when a predetermined valve closing condition is satisfied during operation of the compressor to recover refrigerant, and such that operation of the compressor to recover refrigerant is stopped (S2400) after the start of closing of the gas-side on-off valve.

Description

Technical Field

[0001] The present invention relates to a heat pump system and a controller for controlling the operation of the heat pump system. Background Technology

[0002] EP3115714A1 discloses a heat pump system configured to perform refrigerant recovery operation. During refrigerant recovery operation, the compressor is operated while the on / off valve located in the liquid refrigerant line is closed and the on / off valve located in the gaseous refrigerant line is opened, thereby recovering refrigerant from the utilization side piping section to the heat source side piping section. In the above system, the on / off valve located in the gaseous refrigerant line is closed after the refrigerant recovery operation.

[0003] However, with the above configuration, before the switching valve is closed, the refrigerant in the heat source side pipeline section will flow back to the utilization side pipeline section through the gaseous refrigerant pipe.

[0004] Reference List

[0005] Patent documents

[0006] [Patent Document 1] EP3115714A1 Summary of the Invention

[0007] The purpose of this invention is to provide a heat pump system and a controller for controlling the operation of the heat pump system, which can prevent refrigerant that has been recovered to the heat source side pipe section through refrigerant recovery operation from flowing back to the utilization side pipe section.

[0008] A first aspect of the present invention provides a heat pump system, comprising: a compressor; a heat source-side heat exchanger configured such that a refrigerant flowing in the heat source-side heat exchanger exchanges heat with a fluid passing through the heat source-side heat exchanger; a utilization-side heat exchanger configured such that a refrigerant flowing in the utilization-side heat exchanger exchanges heat with a fluid passing through the utilization-side heat exchanger; a high-pressure refrigerant line connected to a discharge port of the compressor and each of the heat source-side heat exchangers; a liquid refrigerant line connected to each of the heat source-side heat exchangers and the utilization-side heat exchangers; a low-pressure refrigerant line connected to each of the utilization-side heat exchangers and the suction port of the compressor; a liquid-side switching valve disposed in the liquid refrigerant line; and an expansion mechanism disposed in the liquid refrigerant line. A gas-side switching valve disposed in the low-pressure refrigerant line; and a controller configured to control the heat pump system by simultaneously operating the compressor while the liquid-side switching valve is closed and the gas-side switching valve is open, to perform refrigerant recovery operation for recovering refrigerant from a utilization-side pipeline section to a heat source-side pipeline section, the utilization-side pipeline section extending between the liquid-side switching valve and the gas-side switching valve and including at least the utilization-side heat exchanger, the heat source-side pipeline section extending between the gas-side switching valve and the liquid-side switching valve and including at least the compressor, wherein the controller is configured to control the heat pump system in the refrigerant recovery mode such that when a predetermined valve closing condition is met during the operation of the compressor to recover refrigerant, the gas-side switching valve begins to close, and the operation of the compressor for recovering refrigerant stops after the closure of the gas-side switching valve begins.

[0009] Once the compressor used for refrigerant recovery stops operating, the pressure at the compressor's suction port begins to increase, and this pressure increase propagates through the low-pressure refrigerant line. Therefore, if the compressor used for refrigerant recovery stops operating while the gas-side switching valve is still fully open, refrigerant can easily flow back to the utilization side section via the low-pressure refrigerant line. In this respect, the heat pump system with the above-described structure stops the compressor operation after the gas-side switching valve begins to close. Therefore, it is possible to prevent the refrigerant recovered through the refrigerant recovery operation from flowing back to the utilization side section.

[0010] According to the preferred embodiment of the heat pump system described above, the heat pump system further includes a refrigerant leak detector configured to detect refrigerant leaks occurring in the utilization side piping section, wherein the controller is configured to control the heat pump system to perform refrigerant recovery operation when a refrigerant leak is detected.

[0011] With the above-described structure, when a refrigerant leak occurs in the utilization side piping section, the refrigerant can be vented from the utilization side piping section. This prevents further refrigerant leaks and allows for safe repair of the leak point.

[0012] According to another preferred embodiment of the heat pump system described above, the gas-side switching valve is an electric valve.

[0013] The electric valve is configured to rotate an electric motor to move a needle within the valve and close the passage. Therefore, while the timing and speed of the electric valve's closure can be easily controlled, completing the closure takes a relatively long time. In this respect, the heat pump system according to the invention can begin closing the gas-side switching valve much earlier. Therefore, refrigerant backflow through the gas-side switching valve can be effectively prevented.

[0014] According to another preferred embodiment of any of the heat pump systems described above, at least the utilization-side heat exchanger is configured in the utilization-side unit; and at least the compressor, gas-side switching valve, and controller are configured in a heat source-side unit separate from the utilization-side unit.

[0015] A heat pump system with components separated into a utilization-side unit and a heat source-side unit is advantageous for various situations, such as air conditioning systems used in multiple target spaces. With the above configuration, the compressor, gas-side on / off valve, and controller are arranged in the same unit. Therefore, even if the heat pump system is divided into utilization-side and heat source-side units, the controller can control the gas-side on / off valve and compressor from a nearby location. This reliably prevents refrigerant recovered to the heat source-side unit from flowing back to the utilization-side unit.

[0016] According to another preferred embodiment of any of the heat pump systems described above, the Cv value of the gas-side switching valve is greater than the Cv value of the liquid-side switching valve.

[0017] Typically, the diameter of the low-pressure refrigerant line is larger than that of the liquid refrigerant line; therefore, the Cv value of the gas-side switching valve is greater than that of the liquid-side switching valve. Furthermore, the larger the Cv value of the valve, the longer it takes for the valve to fully close. In this respect, the heat pump system according to the present invention can begin closing the gas-side switching valve earlier. Therefore, refrigerant backflow through the gas-side switching valve can be effectively prevented.

[0018] According to another preferred embodiment of any of the heat pump systems described above, the heat pump system further includes: a bypass pipe connected to a liquid refrigerant line at a point between the heat source-side heat exchanger and the liquid-side switching valve, and connected to a low-pressure refrigerant line at a point between the gas-side switching valve and the compressor; a bypass expansion mechanism disposed in the bypass pipe; and a storage tank inserted into the low-pressure refrigerant line at a point between the bypass pipe and the compressor, wherein the controller is configured to open the bypass expansion mechanism during refrigerant recovery operation.

[0019] With the above-described structure, refrigerant can be drawn from the utilization-side piping section to the heat source-side piping section, and the drawn refrigerant can circulate within the heat source-side piping section. Furthermore, the refrigerant can be stored not only in the heat source-side heat exchanger but also in a storage tank. Therefore, the amount of refrigerant to be recovered can be increased. Moreover, the volume of the heat source-side heat exchanger can be determined based on its required heat exchange capacity, regardless of the amount of refrigerant to be recovered. Therefore, the size and design of the heat source-side heat exchanger can be optimized.

[0020] According to another preferred embodiment of any of the heat pump systems described above, the controller is configured to control the heat pump system during refrigerant recovery operation such that the operation of the compressor used for refrigerant recovery stops after the gas-side switching valve is closed.

[0021] With the above structure, even if the compressor stops running quickly and the low-pressure refrigerant pipe on the heat source side is short, refrigerant backflow can be prevented.

[0022] According to another preferred embodiment of any of the heat pump systems described above, the heat pump system further includes an intake pressure detector configured to detect the pressure of the refrigerant flowing in the low-pressure pipe, wherein a predetermined valve closing condition includes the pressure of the refrigerant flowing in the low-pressure pipe being lower than a first predetermined intake pressure value.

[0023] With the above structure, when the pressure in the low-pressure refrigerant line decreases—that is, assuming that most of the refrigerant has been recovered from the utilization side piping section to the heat source side piping section—the flow of refrigerant in the low-pressure refrigerant line can be cut off. Therefore, while recovering most of the refrigerant, the gas-side switching valve can be closed earlier, thereby stopping the compressor operation earlier.

[0024] According to another preferred embodiment of any of the heat pump systems described above with a low-pressure gas state detector, the predetermined valve closing condition further includes that the pressure of the refrigerant flowing in the low-pressure pipe has been maintained below a first predetermined suction pressure value for a second predetermined time.

[0025] With the above structure, the flow of refrigerant in the low-pressure refrigerant line can be cut off when the low pressure in the low-pressure refrigerant line becomes sufficiently low, that is, when the refrigerant has been fully recovered from the utilization side pipeline section to the heat source side pipeline section. Therefore, the gas-side switching valve can be closed earlier while fully recovering the refrigerant, thereby stopping the compressor operation earlier.

[0026] According to another preferred embodiment of any of the heat pump systems described above, the controller is configured to control the refrigerant compressor during refrigerant recovery operation such that the operation of the refrigerant compressor stops when a predetermined compressor stop condition is met after the gas-side switching valve has begun to close. The predetermined compressor stop condition includes at least one of a first condition, a second condition, a third condition, and a fourth condition: In the first condition, the rate of change of pressure of the refrigerant flowing in the high-pressure refrigerant line is lower than a first predetermined rate of change value, and the rate of change of pressure of the refrigerant flowing in the low-pressure refrigerant line is lower than a second predetermined rate of change value that is equal to or different from the first predetermined rate of change value; In the second condition, the pressure of the refrigerant flowing in the low-pressure refrigerant line is lower than a second predetermined suction pressure value that is lower than a first predetermined suction pressure value; In the third condition, a third predetermined time has elapsed after the gas-side switching valve has completed closing; In the fourth condition, a fourth predetermined time has elapsed after the gas-side switching valve has begun to close.

[0027] With the above-described configuration, the compressor can be stopped to complete refrigerant recovery at an appropriate timing. For example, the compressor can be stopped when the heat pump system is in a state that prevents refrigerant from flowing back from the heat source side pipe section to the utilization side pipe section via the low-pressure refrigerant line. As mentioned above, the gas-side switching valve begins to close before the compressor stops operating, regardless of the timing of the compressor stoppage.

[0028] A second aspect of the invention provides a controller for controlling the operation of a heat pump system, the heat pump system comprising: a compressor; a heat source-side heat exchanger configured such that a refrigerant flowing in the heat source-side heat exchanger exchanges heat with a fluid passing through the heat source-side heat exchanger; a utilization-side heat exchanger configured such that a refrigerant flowing in the utilization-side heat exchanger exchanges heat with a fluid passing through the utilization-side heat exchanger; a high-pressure refrigerant line connected to the discharge port of the compressor and each of the heat source-side heat exchangers; a liquid refrigerant line connected to each of the heat source-side heat exchangers and the utilization-side heat exchangers; a low-pressure refrigerant line connected to each of the utilization-side heat exchangers and the suction port of the compressor; a liquid-side switching valve disposed in the liquid refrigerant line; and an expansion mechanism. The system comprises: a liquid refrigerant line; and a gas-side switching valve disposed in the low-pressure refrigerant line; the controller being configured to control the heat pump system by simultaneously operating the compressor while the liquid-side switching valve is closed and the gas-side switching valve is open, to perform refrigerant recovery operation for recovering refrigerant from the utilization-side pipeline section to the heat source-side pipeline section, the utilization-side pipeline section extending between the liquid-side switching valve and the gas-side switching valve and including at least the utilization-side heat exchanger, and the heat source-side pipeline section extending between the gas-side switching valve and the liquid-side switching valve and including at least the compressor; wherein the controller is configured to control the heat pump system in the refrigerant recovery mode such that when a predetermined valve closing condition is met during the operation of the compressor to recover refrigerant, the gas-side switching valve begins to close, and the operation of the compressor for recovering refrigerant stops after the closure of the gas-side switching valve begins.

[0029] Once the compressor used for refrigerant recovery stops operating, the pressure at the compressor's suction port begins to increase, and this pressure increase propagates through the low-pressure refrigerant line. Therefore, if the compressor used for refrigerant recovery stops operating while the gas-side switching valve is still fully open, refrigerant can easily flow back to the utilization-side piping section via the low-pressure refrigerant line. In this regard, the controller with the above-described structure stops the compressor operation after the gas-side switching valve begins to close. Therefore, it is possible to prevent the refrigerant recovered through the refrigerant recovery operation from flowing back to the utilization-side piping section. Furthermore, the above-described effect can also be achieved in existing heat pump systems simply by applying the controller according to the invention. Attached Figure Description

[0030] Figure 1This is a schematic structural diagram of a heat pump system according to a preferred embodiment of the present invention.

[0031] Figure 2 It means Figure 1 The block diagram shown illustrates the functional structure of the controller.

[0032] Figure 3 This is the first part of a flowchart indicating the refrigerant recovery operation performed by the controller.

[0033] Figure 4 This is the second part of the flowchart indicating the refrigerant recovery process.

[0034] Figure 5 This is a table representing examples of conditions used as compressor stop conditions.

[0035] Figure 6 This is a schematic structural diagram of a first modified example of a heat pump system according to a preferred embodiment.

[0036] Figure 7 This is a schematic structural diagram of a second variation of a heat pump system according to a preferred embodiment. Detailed Implementation

[0037] A preferred embodiment of the heat pump system according to the present invention (hereinafter referred to as "this embodiment") will be described with reference to the accompanying drawings. For example, the heat pump system according to this embodiment is an air conditioning system capable of both cooling and heating operation using R32 refrigerant.

[0038] <System Loop Construction>

[0039] Figure 1 This is a schematic diagram of the heat pump system according to this embodiment.

[0040] like Figure 1 As shown, the heat pump system 100 includes a compressor 210, a mode switching mechanism 220, a heat source-side heat exchanger 230, a utilization-side heat exchanger 240, and a storage tank 250. The heat source-side heat exchanger 230 may be equipped with a heat source-side fan 231, and the utilization-side heat exchanger 240 may be equipped with a utilization-side fan 241.

[0041] The heat pump system 100 also includes a discharge-side refrigerant pipe 310, a first gaseous refrigerant pipe 320, a liquid refrigerant pipe 330, a second gaseous refrigerant pipe 340, and a suction-side refrigerant pipe 350. The discharge-side refrigerant pipe 310 is connected to each of the discharge port of the compressor 210 and the mode switching mechanism 220. The first gaseous refrigerant pipe 320 is connected to each of the mode switching mechanism 230 and the heat source-side heat exchanger 230. The liquid refrigerant pipe 330 is connected to each of the heat source-side heat exchanger 230 and the utilization-side heat exchanger 240. The second gaseous refrigerant pipe 340 is connected to each of the utilization-side heat exchanger 240 and the mode switching mechanism 220. The suction-side refrigerant pipe 350 is connected to each of the mode switching mechanism 240 and the suction port of the compressor 210. A storage tank 250 is inserted into the suction-side refrigerant pipe 350.

[0042] The heat pump system 100 further includes a heat source-side expansion mechanism 410, a liquid-side on / off valve 420, a liquid-side shut-off valve 430, a utilization-side expansion mechanism 440, a gas-side shut-off valve 450, and a gas-side on / off valve 460. The heat source-side expansion mechanism 410, liquid-side on / off valve 420, liquid-side shut-off valve 430, and utilization-side expansion mechanism 440 are sequentially arranged in the liquid refrigerant pipe 330 along the direction from the heat source-side heat exchanger 230 toward the utilization-side heat exchanger 240. The gas-side shut-off valve 450 and gas-side on / off valve 460 are sequentially arranged in the second gas refrigerant pipe 340 along the direction from the utilization-side heat exchanger 240 toward the mode switching mechanism 220. The heat source-side expansion mechanism 410 and the utilization-side expansion mechanism 440 correspond to the expansion mechanisms according to the present invention.

[0043] The heat pump system 100 also includes a refrigerant heat exchanger 260, a bypass pipe 360, and a bypass expansion mechanism 470. The refrigerant heat exchanger 260 is arranged in the liquid refrigerant pipe 330 at a location between the heat source-side expansion mechanism 410 and the liquid-side switching valve 420. The bypass pipe 360 ​​connects to each of the liquid refrigerant pipe 330 and the suction-side refrigerant pipe 350, and is connected in parallel with the utilization-side heat exchanger 240. More specifically, the bypass pipe 360 ​​connects to the liquid refrigerant pipe 330 at a point between the heat source-side expansion mechanism 410 and the refrigerant heat exchanger 260, and connects to the suction-side refrigerant pipe 350 at a point between the mode switching mechanism 220 and the storage tank 250. A portion of the bypass pipe 360 ​​is arranged within the refrigerant heat exchanger 260. The bypass expansion mechanism 470 is arranged in the bypass pipe 360 ​​at a point between the liquid refrigerant pipe 330 and the refrigerant heat exchanger 260.

[0044] The heat pump system 100 also includes a discharge-side refrigerant status detector 510, an ambient temperature detector 520, a refrigerant leak detector 530, and a suction-side refrigerant status detector 540. The discharge-side refrigerant status detector 510 is attached to the discharge-side refrigerant line 310. The ambient temperature detector 520 is located near the heat source-side heat exchanger 230. The refrigerant leak detector 530 is located near the utilization-side heat exchanger 240. The suction-side refrigerant status detector 540 is attached to the suction-side refrigerant line 350 at a point between the storage tank 250 and the compressor 210. The suction-side refrigerant status detector 540 corresponds to each of the evaporation temperature detector and the suction pressure detector according to the invention.

[0045] The heat pump system 100 also includes a controller 600. The controller 600 is connected to each of the aforementioned machines via a wired / wireless communication path (not shown).

[0046] The heat pump system 100 may have a heat source side unit 110 and a utilization side unit 120 as separate units. For example, the heat source side unit 110 is an externally located unit, and the utilization side unit 120 is a unit located in or near the target space to be air-conditioned. In this case, at least the compressor 210, the gas-side on / off valve 460, the liquid-side on / off valve 420, and the controller 600 are located in the heat source side unit 110, and at least the utilization side heat exchanger 240 is located in the utilization side unit 120.

[0047] In this embodiment, the liquid refrigerant pipe 330 and the second gaseous refrigerant pipe 340 extend between the heat source side unit 110 and the utilization side unit 120. The utilization side expansion mechanism 440, utilization side heat exchanger 240, utilization side fan 241, and refrigerant leak detector 530, as described above, are arranged in the utilization side unit 120, while other equipment is arranged in the heat source side unit 110. The controller 600 can be connected to the equipment in the utilization side unit 120 via a sub-controller (not shown) arranged in the utilization side unit 120. The sub-controller in the utilization side unit 120 can be considered part of the controller 600.

[0048] <Functions of Machines and Equipment>

[0049] The compressor 210 has an intake port and a discharge port, and is configured to draw in refrigerant through the intake port, compress the drawn-in refrigerant internally, and discharge the compressed refrigerant through the discharge port.

[0050] The mode switching mechanism 220 is configured to switch between a cooling mode connection and a heating mode connection. In cooling mode connection, the mode switching mechanism 220 connects the discharge-side refrigerant pipe 310 to the first gaseous refrigerant pipe 320 to form a high-pressure refrigerant pipe, and connects the suction-side refrigerant pipe 350 to the second gaseous refrigerant pipe 340 to form a low-pressure refrigerant pipe. In heating mode connection, the mode switching mechanism 220 connects the discharge-side refrigerant pipe 310 to the second gaseous refrigerant pipe 340 to form a high-pressure refrigerant pipe, and connects the suction-side refrigerant pipe 350 to the first gaseous refrigerant pipe 320 to form a low-pressure refrigerant pipe. Here, the high-pressure refrigerant pipe is a piping (flow path) connected to the discharge port of the compressor 210 and each of the heat source-side heat exchangers 230, and the low-pressure refrigerant pipe is a piping (flow path) connected to each of the utilization-side heat exchangers 240 and the suction port of the compressor 210. The mode switching mechanism 220 may be a four-way reversing valve.

[0051] The heat source-side heat exchanger 230 is configured to allow refrigerant to flow therein from the first gaseous refrigerant line 320 to the liquid refrigerant line 330 and vice versa. The heat source-side heat exchanger 230 is also configured to allow heat exchange between the refrigerant flowing therein and the fluid passing through it. In this embodiment, the heat source-side heat exchanger 230 is configured to allow outdoor air to pass through it. The heat source-side fan 231 is configured to facilitate the flow of air through the heat source-side heat exchanger 230.

[0052] The side heat exchanger 240 is configured to allow refrigerant to flow therein from the liquid refrigerant line 330 to the second gaseous refrigerant line 340 and vice versa. The side heat exchanger 240 is also configured to allow heat exchange between the refrigerant flowing therein and the fluid passing through it. In this embodiment, the side heat exchanger 240 is configured to allow indoor and / or outdoor air in the target space to pass through it. The side fan 241 is configured to facilitate the flow of air passing through the side heat exchanger 240. The air that has passed through the side heat exchanger 240 is supplied to the target space.

[0053] The storage tank 250 is configured to separate gaseous refrigerant from the refrigerant flowing into the tank and to transport the separated gaseous refrigerant forward. The storage tank 250 is also configured to store excess refrigerant in the heat pump circuit of the heat pump system 100.

[0054] The refrigerant heat exchanger 260 is configured to exchange heat between the refrigerant flowing in the liquid refrigerant line 330 and the refrigerant that has flowed into the bypass line 360 ​​and has been depressurized and expanded by the bypass expansion mechanism 470. The refrigerant heat exchanger 260 may have two flow channels that respectively form a portion of the liquid refrigerant line 330 and a portion of the bypass line 360, and heat conduction exists between them.

[0055] The heat source-side expansion mechanism 410 is configured to depressurize and expand the refrigerant flowing through it when the heat source-side expansion mechanism 410 is partially open. More specifically, the heat source-side expansion mechanism 410 is configured, under the control of the controller 600, to depressurize and expand the refrigerant flowing from the utilization-side heat exchanger 240 to the heat source-side heat exchanger 230 in the liquid refrigerant line 330 during heating operation of the heat pump system 100. The heat source-side expansion mechanism 410 may be an electrically operated expansion valve.

[0056] The liquid-side switching valve 420 is configured to regulate the flow of refrigerant therethrough. More specifically, the liquid-side switching valve 420 is configured, under the control of the controller 600, to cut off the flow of refrigerant in at least a portion of the liquid refrigerant line 330 when the liquid-side switching valve 420 is fully closed. The liquid-side switching valve 420 may be an electrically operated expansion valve.

[0057] The liquid-side shut-off valve 430 is configured to stop refrigerant flow when manually closed. The liquid-side shut-off valve 430 remains fully open unless manually closed. The liquid-side shut-off valve 430 may be a service valve configured to switch between open and closed states, allowing refrigerant to be charged into and discharged from the heat pump circuit.

[0058] The side expansion mechanism 440 is configured to depressurize and expand the refrigerant flowing through it when the side expansion mechanism 440 is partially open. More specifically, the side expansion mechanism 440 is configured, under the control of the controller 600, to depressurize and expand the refrigerant flowing from the heat source side heat exchanger 230 to the utilization side heat exchanger 240 in the liquid refrigerant line 330 during the cooling operation of the heat pump system 100. The side expansion mechanism 440 can be an electrically operated expansion valve.

[0059] The gas-side shut-off valve 450 is configured to stop refrigerant flow when manually closed. The gas-side shut-off valve 450 remains fully open unless manually closed. The liquid-side shut-off valve 430 may be a service valve configured to switch between open and closed states, allowing refrigerant to be charged into and discharged from the heat pump circuit.

[0060] The gas-side switching valve 460 is configured to regulate the flow of refrigerant therethrough. More specifically, the gas-side switching valve 460 is configured, under the control of the controller 600, to cut off the flow of refrigerant in at least a portion of the liquid refrigerant line 330 when the gas-side switching valve 460 is fully closed. The gas-side switching valve 460 may be an electrically operated expansion valve.

[0061] Typically, the diameter of the second gaseous refrigerant pipe 340 is larger than the diameter of the liquid refrigerant pipe 330. Therefore, the Cv value of the gas-side switching valve 460 is greater than the Cv value of the liquid-side switching valve 420. For example, the Cv value of the gas-side switching valve 460 is more than five times greater than the Cv value of the liquid-side switching valve 420. The Cv value of the gas-side switching valve 410 can be 5, and the Cv value of the liquid-side switching valve 420 can be 0.6. In this case, the Cv value of the heat source-side expansion mechanism 410 can be 0.3.

[0062] The bypass expansion mechanism 470 is configured to depressurize and expand the refrigerant flowing through it when the bypass expansion mechanism 460 is partially open. More specifically, the bypass expansion mechanism 470 is configured, under the control of the controller 600, to depressurize and expand the refrigerant flowing from the liquid refrigerant line 330 to the suction-side refrigerant line 350 in the bypass line 360 ​​during operation of the heat pump system 100 in refrigeration operation and refrigerant recovery operation (described later). The bypass expansion mechanism 470 may be an electrically operated expansion valve.

[0063] In the following description, the heat source-side expansion mechanism 410, the liquid-side switching valve 420, the utilization-side expansion mechanism 440, the gas-side switching valve 460, and the bypass expansion mechanism 470 are collectively referred to as "control valves" as needed.

[0064] The discharge-side refrigerant status detector 510 is configured to detect the pressure and / or temperature of the refrigerant flowing in the discharge-side refrigerant line 310, and to continuously or periodically transmit discharge-side refrigerant information, indicating the detected pressure (hereinafter referred to as "discharge pressure Pc") and / or the detected temperature (hereinafter referred to as "discharge temperature Tdi"), to the controller 600. Alternatively or additionally, the discharge-side refrigerant status detector 510 may transmit discharge-side refrigerant information when the detected discharge pressure Pc and / or discharge temperature Td changes by a predetermined amount, and / or upon receiving a request from the controller 600. The discharge-side refrigerant status detector 510 may be a capacitive pressure sensor and / or a thermistor.

[0065] An ambient temperature detector 520 is configured to detect the temperature of the fluid (outdoor air) passing through the heat source-side heat exchanger 230 and continuously or periodically send ambient temperature information indicating the detected temperature (hereinafter referred to as "ambient temperature Ta") to the controller 600. Alternatively or additionally, the ambient temperature detector 520 may send ambient temperature information when the detected temperature Ta changes by a predetermined amount and / or when a request is received from the controller 600. The ambient temperature detector 520 may be a thermistor configured in the airflow path of the outdoor air flowing through the heat source-side heat exchanger 230, located upstream of the heat source-side heat exchanger 230. In other words, the ambient temperature detector 520 is configured to detect the temperature of the fluid undergoing heat exchange with the refrigerant in the heat source-side heat exchanger 230.

[0066] The refrigerant leak detector 530 is configured to detect the occurrence of refrigerant leaks in the utilization-side unit 120 and continuously or periodically send refrigerant leak information to the controller 600. The refrigerant leak information is information indicating whether a refrigerant leak (hereinafter simply referred to as "refrigerant leak") has occurred in the utilization-side unit 120. Alternatively or additionally, the refrigerant leak detector 530 may send refrigerant leak information when a refrigerant leak has occurred.

[0067] The refrigerant leak detector 530 may be a semiconductor gas sensor that reacts to the refrigerant used in the heat pump system 100. In this case, the refrigerant leak detector 520 detects the refrigerant concentration in the air surrounding the refrigerant leak detector 540 and outputs a detection value indicating the detected concentration as refrigerant leak information. Whether the detection value is greater than a predetermined threshold indicates whether a refrigerant leak has occurred. The refrigerant leak detector 530 is disposed in the utilization-side unit 120 or the target space. In the case of a refrigerant heavier than air, such as R32 refrigerant, the refrigerant leak detector 530 is preferably disposed on or near the inner bottom surface of the air chamber (not shown) where the utilization-side heat exchanger 240 is arranged.

[0068] The suction-side refrigerant status detector 540 is configured to detect the pressure of the refrigerant flowing in the suction-side refrigerant line 350 and the evaporation temperature of the refrigerant flowing in the suction-side refrigerant line 350. The suction-side refrigerant status detector 540 is also configured to continuously or periodically transmit suction-side refrigerant information, representing the detected pressure (hereinafter referred to as "suction pressure Pe") and the detected evaporation temperature TeS, to the controller 600. Alternatively or additionally, the suction-side refrigerant status detector 540 may transmit suction-side refrigerant information when the detected suction pressure Pe and / or evaporation temperature TeS changes by a predetermined amount, and / or upon receiving a request from the controller 600.

[0069] The suction-side refrigerant status detector 540 may include: a capacitive pressure sensor configured to detect the pressure of the refrigerant flowing in the suction-side refrigerant line 350; and a thermistor configured to detect the temperature of the refrigerant flowing in the suction-side refrigerant line 350. The suction-side refrigerant status detector 540 may also include a storage medium and a calculator. In this case, the storage medium pre-stores table information indicating a known correlation between the refrigerant pressure and the refrigerant evaporation temperature TeS at that pressure. The calculator calculates the refrigerant evaporation temperature TeS based on the detected pressure and the table. However, this calculation may be performed by the controller 600.

[0070] In the following description, the discharge-side refrigerant status detector 510, the ambient temperature detector 520, the refrigerant leak detector 530, and the suction-side refrigerant status detector 540 are collectively referred to as "sensors" as needed.

[0071] The controller 600 is configured to switch the mode switching mechanism 220 between cooling mode connection and heating mode connection according to instructions made by the user or an external controller, and to control the cooling and heating operation of the heat pump system 100.

[0072] During refrigeration operation, the controller 600 controls the equipment of the heat pump system 100 so that the refrigerant discharged from the compressor 210 flows sequentially through each of the heat source side heat exchanger 230, the utilization side heat exchanger 240 and the bypass pipe 360 ​​and the storage tank 250, and is drawn into the compressor 210. Figure 1 The arrows shown indicate the direction of refrigerant flow during cooling operation of the heat pump system 100. During cooling operation, the heat source side unit 110 functions as a condenser, and the utilization side unit 120 functions as an evaporator.

[0073] During heating operation, the controller 600 controls the equipment, causing the refrigerant discharged from the compressor 210 to flow sequentially through the utilization-side heat exchanger 240, the heat source-side heat exchanger 230, and the storage tank 250, and then be drawn into the compressor 210. Specifically, when the mode switching mechanism 220 is in heating mode, the first gaseous refrigerant pipe 320 is part of the suction-side refrigerant pipe 350, and the second gaseous refrigerant pipe 340 is part of the discharge-side refrigerant pipe 310. During heating operation, the heat source-side unit 110 functions as an evaporator, and the utilization-side unit 120 functions as a condenser.

[0074] The controller 600 is also configured to control the heat pump system 100 to perform refrigerant recovery operation when a refrigerant leak is detected. Refrigerant recovery operation is performed by operating the compressor 210 simultaneously with the liquid-side switching valve 420 closed and the gas-side switching valve 460 open, recovering refrigerant from the utilization-side piping section 102 to the heat source-side piping section 101. Here, the heat source-side piping section 101 is a piping section extending between the gas-side switching valve 460 and the liquid-side switching valve 420 and including at least the compressor 210. The heat source-side piping section 101 also includes a heat source-side heat exchanger 230. The utilization-side piping section 102 is a piping section extending between the liquid-side switching valve 420 and the gas-side switching valve 460 and including at least the utilization-side heat exchanger 240.

[0075] In this embodiment, the heat source side piping section 101 includes: a portion of the second gaseous refrigerant pipe 340 connected to the mode switching mechanism 220; the mode switching mechanism 220; the suction side refrigerant pipe 350; the storage tank 250; the compressor 210; the discharge side refrigerant pipe 310; the first gaseous refrigerant pipe 320; the heat source side heat exchanger 230; a portion of the liquid refrigerant pipe 330 connected to the heat source side heat exchanger 230; the heat source side expansion mechanism 410; the refrigerant heat exchanger 260; the bypass pipe 360; and the bypass expansion mechanism 470. The utilization side piping section 102 includes: a portion of the liquid refrigerant pipe 330 connected to the utilization side heat exchanger 240; a liquid side shut-off valve 430; the utilization side expansion mechanism 440; a portion of the second gaseous refrigerant pipe 340 connected to the utilization side heat exchanger 240; and a gas side shut-off valve 450.

[0076] During refrigerant recovery operation, the controller 600 controls the equipment of the heat pump system 100, causing the refrigerant present in the utilization side piping section 102 to be drawn into the suction port of the compressor 210 via the second gaseous refrigerant pipe 340, and then flows through the heat source side heat exchanger 230, bypass pipe 360, and storage tank 250 within the heat source side piping section 101. During the flow of the refrigerant within the heat source side piping section 101, it mainly accumulates in the storage tank 250 and the heat source side heat exchanger 230.

[0077] The controller 600 is also configured to control the compressor 210 during refrigerant recovery operation such that the rate of increase in compressor speed when the ambient temperature Ta is higher than or equal to a predetermined ambient temperature value Tath is lower than the rate of increase in compressor speed when the ambient temperature Ta is lower than a predetermined ambient temperature value Ta_th. Here, "compressor speed" refers to the rotational speed of the compressor 210, for example, in terms of the number of rotations per minute. The rate of increase in compressor speed is, for example, the increase in compressor speed per unit time.

[0078] The controller 600 is also configured to control the heat pump system 100 during refrigerant recovery operation such that the gas-side switching valve 460 begins to close when a predetermined valve closing condition is met during operation of the compressor 210 to recover refrigerant. The controller 600 is also configured to control the heat pump system 100 such that operation of the compressor 210 for refrigerant recovery stops after the closure of the gas-side switching valve 460 begins. Details regarding the controller 600 will be described below.

[0079] <Functional Composition of the Controller>

[0080] The controller 600 includes: arithmetic circuitry, such as a CPU (Central Processing Unit); working memory used by the CPU, such as RAM (Random Access Memory); a recording medium storing control programs and information used by the CPU, such as ROM (Read-Only Memory); and timers, although they are not shown. The controller 600 is configured to perform information processing and signal processing by executing control programs through the CPU to control the operation of the heat pump system 100. Therefore, the function of the controller 600 is implemented by executing programs.

[0081] Figure 2 This is a block diagram representing the functional structure of controller 600.

[0082] like Figure 2 As shown, the controller 600 includes a storage unit 610, an information input unit 620, a normal operation controller 630, an information output unit 640, and a refrigerant recovery controller 650.

[0083] The storage unit 610 stores information in a form readable by the refrigerant recovery controller 650. The stored information may include conditions and values ​​used by the normal operation controller 630 and the refrigerant recovery controller 610. The stored information may be prepared in advance based on experiments, etc.

[0084] The information input unit 620 is configured to acquire information from sensors required for controlling the operation of the heat pump system 100 and transmit the acquired information to the refrigerant recovery controller 650. The information input unit 620 may further transmit the acquired information to the normal operation controller 630. The information to be acquired includes, as described above, emission-side refrigerant information, ambient temperature information, refrigerant leakage information, and suction-side refrigerant information. The information input unit 620 may include a wired / wireless communication interface for communicating with each sensor. Under the control of the refrigerant recovery controller 650, the information input unit 620 may send requests to the sensors requesting information.

[0085] The conventional operation controller 630 is configured to control both cooling and heating operations of the heat pump system 100. For cooling operation, the conventional operation controller 620 is configured to switch the control mode switching mechanism 220 to or maintain a cooling mode connection, fully opening the heat source-side expansion mechanism 410, the liquid-side switching valve 420, and the gas-side switching valve 460, and partially opening the utilization-side expansion mechanism 440 and the bypass expansion mechanism 470. For heating operation, the conventional operation controller 630 is configured to switch the control mode switching mechanism 220 to or maintain a heating mode connection, fully opening the gas-side switching valve 460, the utilization-side expansion mechanism 440, and the liquid-side switching valve 420, partially opening the heat source-side expansion mechanism 410, and fully closing the bypass expansion mechanism 470. The conventional operation controller 630 is also configured to control the compressor 210, the heat source-side fan 231, and the utilization-side fan 241 to operate in both cooling and heating operations. The conventional operation controller 630 may include a wired / wireless communication interface for communicating with each of the mode switching mechanism 220, control valve, compressor 210, heat source side fan 231, and utilization side fan 241.

[0086] Regarding the control of compressor 210, the conventional operation controller 630 is configured to control the compressor speed so that the evaporating temperature TeS is close to the target evaporating temperature value TeS_tgt. The target evaporating temperature value TeS_tgt is used regardless of whether the heat pump system 100 is in cooling operation or refrigerant recovery operation, but the value of the target evaporating temperature value TeS_tgt differs, as described below. The conventional operation controller 630 is also configured to monitor whether the discharge pressure Pc remains below a predetermined threshold, and to reduce the compressor speed (i.e., perform droop control) when the discharge pressure Pb has exceeded the predetermined threshold.

[0087] The conventional operation controller 630 can also be configured to control the heat pump system 100 under the control of the refrigerant recovery controller 650 during refrigerant recovery operation.

[0088] The information output unit 640 is configured to output information to the user of the heat pump system 100 or to external devices such as information output devices under the control of the refrigerant recovery controller 650. The information output unit 640 may include a display device, a light, a speaker, and a wired / wireless communication interface for transmitting information to external devices. Therefore, the information output unit 640 is configured to output information via images, light, sound, communication signals, etc.

[0089] The refrigerant recovery controller 650 is configured to perform refrigerant recovery operation, for example, by using a conventional operation controller 630. The refrigerant recovery controller 650 includes a leak detection unit 651, a temperature detection unit 652, an acceleration switching unit 653, and a timing control unit 654.

[0090] The leak detection unit 651 is configured to detect the occurrence of a refrigerant leak based on refrigerant leak information from the refrigerant leak detector 530. For example, the leak detection unit 651 is configured to determine that a refrigerant leak has occurred when the concentration of refrigerant detected by the refrigerant leak detector 530 is greater than a predetermined concentration value. However, this determination can be performed by the refrigerant leak detector 530 or the information input unit 620. The moving average of the time series data of the detected concentration can be used for the above determination. The leak detection unit 651 can passively receive refrigerant leak information continuously or periodically sent by the refrigerant leak detector 530, or actively acquire refrigerant leak information by periodically sending requests to the refrigerant leak detector 520.

[0091] The temperature detection unit 652 is configured to acquire ambient temperature information from the ambient temperature detector 520. The temperature detection unit 652 can passively receive ambient temperature information continuously or periodically sent by the ambient temperature detector 520, or actively acquire ambient temperature information by sending a request to the ambient temperature detector 520 when the leak detection unit 651 determines that a refrigerant leak has occurred.

[0092] The acceleration switching unit 653 is configured to set the target rate of increase value Rv_tgt based on whether the acquired ambient temperature Ta is higher than or equal to a predetermined ambient temperature value Ta_th. More specifically, when the ambient temperature Ta is higher than or equal to the predetermined ambient temperature value Ta_th, the acceleration switching unit 653 is configured to set the target rate of increase value Rv_tgt to be lower than the target rate of increase value Rv_tgt when the ambient temperature Ta is lower than the predetermined ambient temperature value Ta_th.

[0093] The timing control unit 654 is configured to perform refrigerant recovery operation and control the timing of events during the refrigerant recovery operation. Specifically, the timing control unit 654 is configured to control the compressor 210 to increase the compressor speed by a set target increase rate value Rv_tgt, control the gas-side switching valve 460 to close, and control the compressor 210 to stop the operation for refrigerant recovery after the gas-side switching valve 460 begins to close. The function of the timing control unit 654 is described in detail in the following description of the operation of the controller 600.

[0094] <Controller Operation>

[0095] The leak detection unit 651 of the controller 600 repeatedly checks whether a refrigerant leak has occurred during periods when the compressor 210 is not running, during cooling operation, and during heating operation. When a refrigerant leak is detected, the controller 600 initiates refrigerant recovery operation.

[0096] If a refrigerant leak is detected while the compressor 210 is not operating and the mode switching mechanism 220 is not in cooling mode, the controller 600 controls the mode switching mechanism 200 to switch to cooling mode and then initiates refrigerant recovery operation. If a refrigerant leak is detected during cooling operation, the controller 600 controls the compressor 210 to stop and then initiates refrigerant recovery operation. If a refrigerant leak is detected during heating operation, the controller 600 controls the mode switching mechanism 220 to switch to cooling mode and controls the compressor 210 to stop and then initiates refrigerant recovery operation. In any case, the controller 600 is configured to control the mode switching mechanism 220 to maintain cooling mode connection during refrigerant recovery operation.

[0097] When a refrigerant leak is detected, the refrigerant recovery controller 650 can output an alarm message via the information output unit 640 to notify the user of the refrigerant leak. Preferably, the refrigerant recovery controller 650 sends a signal to the user-side unit 120, so that the alarm message is also output from the user-side unit 110's display device, light, speaker, etc. (not shown).

[0098] Figure 3 This is the first part of a flowchart illustrating the refrigerant recovery operation performed by the controller 600. Figure 4 This is the second part of the flowchart.

[0099] In step S1100, the timing control unit 654 of the controller 600 controls the heat source-side expansion mechanism 410 to be fully open, and also controls the bypass expansion mechanism 470 to be fully open. At this point, the gas-side switching valve 460 should already be open, and the compressor 210 should still be stopped. Therefore, when the compressor 210 subsequently starts operating, the refrigerant can flow smoothly within the heat source-side pipe section 101.

[0100] In step S1200, the timing control unit 654 controls the liquid-side switch valve 420 to close. This prevents refrigerant from flowing into the utilization-side pipe section 102 via the liquid refrigerant pipe 330 when the compressor 210 starts operating.

[0101] In step S1300, the timing control unit 654 sets the target evaporating temperature value TeS_tgt used to control the compressor speed to a value lower than that normally used in refrigeration operation. More specifically, the timing control unit 654 changes the target evaporating temperature value TeS_tgt from a first target evaporating temperature value TeS_1 to a second target evaporating temperature value TeS_2. The first target evaporating temperature value TeS_1 is the default value, and the second target evaporating temperature value TeS_2 is a value lower than the first target evaporating temperature value TeS_1. For example, the first target evaporating temperature value TeS_1 used in normal refrigeration operation is -6 degrees Celsius, and the second target evaporating temperature value TeS_2 is -30 degrees Celsius. Thus, even if the evaporating temperature TeS becomes lower, the compressor 210 can continue to operate in refrigerant recovery operation. However, the measures for maintaining the operation of the compressor 210 are not limited to this.

[0102] In step S1400, the timing control unit 654 controls the utilization-side expansion mechanism 440 to open. Therefore, when the compressor 210 starts operating, the refrigerant can flow smoothly from the utilization-side pipe section 102. Preferably, the utilization-side expansion mechanism 440 opens gradually.

[0103] In step S1500, the timing control unit 654 controls the compressor 210 to start operation. This allows the refrigerant present in the utilization side pipe section 102 to begin being drawn into the heat source side pipe section 101 via the second gaseous refrigerant pipe 340. Preferably, the operation of the compressor 210 begins only after a first predetermined time T_1 has elapsed since the compressor 210 stopped operating. For example, the first predetermined time T_1 is 1 minute. This ensures that the control valve is reliably prepared before the compressor 210 begins operation.

[0104] Through the steps S1100 to S1500 described above, the compressor can start operating with the liquid-side switching valve closed and the heat source-side expansion mechanism 410, bypass expansion mechanism 470, utilization-side expansion mechanism 440, and gas-side switching valve 460 open. However, the measures for preparing the control valve to this state are not limited to the steps S1100 to S1400 described above.

[0105] In step S1600, the temperature detection unit 652 acquires the ambient temperature Ta, and the acceleration switching unit 653 determines whether the acquired ambient temperature Ta is lower than a predetermined ambient temperature value Ta_th. The moving average of the time series data of the detected ambient temperature Ta can be used for the above determination. If the ambient temperature Ta is lower than the predetermined ambient temperature value Ta_th (S1600: Yes), the process proceeds to step S1700. If the ambient temperature Ta is higher than or equal to the predetermined ambient temperature value Ta_th (S1600: No), the process proceeds to step S1800. For example, the predetermined ambient temperature value Ta_th is 35 degrees Celsius.

[0106] In step S1700, the acceleration switching unit 653 sets the first predetermined acceleration rate value Rv_1 to the target acceleration rate value Rv_tgt.

[0107] In step S1800, the acceleration switching unit 653 sets the second predetermined increase rate value Rv_2 to the target increase rate value Rv_tgt. Here, the second predetermined increase rate value Rv_2 is lower than the first predetermined increase rate value Rv_1.

[0108] In step S1900, the timing control unit 654 controls the compressor 210 so that the compressor speed begins to increase at a target increase rate value Rv_tgt with a set value. The timing control unit 654 can control the compressor 210 to start rotating at a predetermined frequency, and then increase the compressor speed by increasing the frequency by a predetermined step at predetermined intervals. The predetermined step can be determined for each interval based on the evaporation temperature TeS, etc. In this case, the target increase rate value Rv_tgt can be used as an upper limit for the increase step in each interval. In other words, the timing control unit 654 can set an upper limit for the step of the frequency to be increased in each interval in step S1800, while essentially not setting an upper limit in step S1700.

[0109] Compressor 210 is controlled to gradually increase its frequency so that the evaporating temperature TeS approaches the target evaporating temperature value TeS_tgt as described above. However, during refrigerant recovery operation, the evaporating temperature TeS will not reach the target evaporating temperature value TeS_tgt because the target evaporating temperature value TeS_tgt has already decreased in step S1300. Therefore, compressor 210 continues to operate while increasing its speed. When the process proceeds to step S1800, the time taken until the compressor speed reaches the same speed is longer than when the process proceeds to step S1700.

[0110] Through the steps S1600 to S1900 described above, the compressor speed can be increased while the rate of increase is slower when the ambient temperature Ta is relatively high.

[0111] In step S2000, the timing control unit 654 determines whether a predetermined valve closing condition has been met. The predetermined valve closing condition indicates that the refrigerant has been sufficiently recovered from the utilization side piping section 102 to the heat source side piping section 101.

[0112] In this embodiment, the predetermined valve closing condition is that the inhalation pressure Pe has been maintained below a first predetermined inhalation pressure value Pe_1 for a second predetermined time T_2. For this determination, the timing control unit 654 acquires the inhalation pressure Pe and determines whether the predetermined valve closing state is met. The moving average of the time series data of the detected inhalation pressure Pe can be used for this determination. For example, the first predetermined inhalation pressure value Pe_1 is 3.0 kPa, and the second predetermined time T_2 is 30 seconds. However, the duration of the second predetermined time T_2 can be excluded from the predetermined valve closing condition described above.

[0113] If the inhalation pressure Pe is not lower than the first predetermined inhalation pressure value Pe_1, or if the inhalation pressure Pe is lower than the first predetermined inhalation pressure value Pe_1 but is not maintained for the second predetermined time T_2 (S2000: No), then the judgment in step S2200 is repeated. If the inhalation pressure Pe remains lower than the first predetermined inhalation pressure value Pe_1 for the second predetermined time T_2 (S2000: Yes), then the process proceeds to step S2100.

[0114] In step S2100, the timing control unit 654 controls the gas-side switching valve 460 to begin closing. This closes the gas-side switching valve 460 to prevent refrigerant from flowing back from the heat source side piping section 101 to the utilization side piping section 102 via the second gas refrigerant pipe 340, even if the compressor 210 subsequently stops operating. Preferably, the gas-side switching valve 460 closes gradually. For example, the timing control unit 654 controls the gas-side switching valve 460 to begin closing by sending a cut-off signal to the gas-side switching valve 460. This cut-off signal can be a pulse signal with the pulse count decreasing to zero.

[0115] In step S2200, the timing control unit 654 determines whether a predetermined compressor stop condition is met. The predetermined compressor stop condition indicates a condition that prevents refrigerant from flowing back from the heat source side pipe section 101 to the utilization side pipe section 102 via the second gas refrigerant pipe 340 even if the compressor 210 stops operating, and / or a condition that the compressor 210 needs to stop operating for safety reasons, etc. If the predetermined compressor stop condition is not met (S2200: No), the determination in step S2200 is repeated. If the predetermined compressor stop condition is met (S2200: Yes), the process proceeds to step S2300.

[0116] Figure 5This is a table showing examples of compressor stop conditions. For example, compressor stop conditions include... Figure 5 At least one of the first to fourth conditions shown.

[0117] The first condition is as follows: the rate of change of emission pressure Pc (hereinafter referred to as "emission pressure change rate |Rpc|") is lower than a predetermined emission pressure change rate value Rpc_th, and the rate of change of intake pressure Pe (hereinafter referred to as "intake pressure change rate |Rpe|") is lower than a predetermined intake pressure change rate value Rpe_th. The predetermined intake pressure change rate value Rpe_th may be equal to or different from the predetermined emission pressure change rate value Rpc_th. Here, the emission pressure change rate |Rpc| can be the absolute value of the change in emission pressure Pc per unit time, and the intake pressure change rate |Rpe| can be the absolute value of the change in intake pressure Pe per unit time. For example, both the predetermined emission pressure change rate value Rpc_th and the predetermined intake pressure change rate value Rpe_th are 0.2 kgf / cm² / s. 2 The moving average of the time series data of the detected emission pressure Pc and the moving average of the time series data of the detected inhalation pressure Pe can be used to determine this condition.

[0118] The second condition is as follows: the inhalation pressure Pe is lower than a second predetermined inhalation pressure value Pe_2, which is lower than a first predetermined inhalation pressure value Pe_1 used in step S2000. For example, the second predetermined inhalation pressure value Pe_2 is 1.0 kPa. The moving average of the time series data of the detected inhalation pressure Pe can be used to determine this condition.

[0119] The third condition is as follows: a third predetermined time T_3 has elapsed after the gas-side switching valve 460 has been closed. For example, the third predetermined time T_3 is 2 minutes. However, the third predetermined time T_3 can be zero. The timing control unit 654 can detect the completion of the closure of the gas-side switching valve 460 by using a sensor.

[0120] The fourth condition is as follows: a fourth predetermined time T_4 has elapsed since the gas-side switching valve 460 began closing in step S2100. Preferably, the fourth predetermined time T_4 is longer than the time period required for the gas-side switching valve 460 to close.

[0121] The timing control unit 654 may use only one of the first to fourth conditions described above. Alternatively, the timing control unit 654 may use any combination of two or more of the first to fourth conditions as an AND condition (logical AND) or an OR condition (logical OR). However, the predetermined compressor stop condition is not limited to these. In any case, the timing control unit 654 is configured to acquire the information required to determine the predetermined compressor stop condition.

[0122] exist Figure 4 In step S2300, the timing control unit 654 will be controlled to close using the side expansion mechanism 440.

[0123] In step S2400, the timing control unit 654 controls the compressor 210 to stop operating and controls the heat source side expansion mechanism 410 and the bypass expansion mechanism 470 to close. For example, the timing control unit 654 controls the compressor 210 to stop operating by controlling the power supply to the compressor 210.

[0124] Through steps S2000 to S2400 described above, when the refrigerant recovery operation can be completed or should be completed, the operation of the compressor 210 can be stopped and the control valve closed. Then, the refrigerant recovery operation terminates. When the refrigerant recovery operation is about to end, the gas-side switching valve 460 begins to close before the compressor 210 starts operating. The timing control unit 654 can terminate the refrigerant recovery operation when predetermined termination conditions have been met, regardless of the predetermined valve closing conditions and predetermined compressor stopping conditions described above. However, even in this case, it is desirable for the timing control unit 654 to control the compressor 210 to stop after the closing of the gas-side switching valve 460 has begun, or more preferably after the closing of the gas-side switching valve 460 has been completed.

[0125] When the refrigerant recovery operation has terminated, the refrigerant recovery controller 650 can output termination information via the information output unit 640 to notify the user of the termination of the refrigerant recovery operation. Preferably, the refrigerant recovery controller 650 sends a signal to the user-side unit 120, so that the termination information is also output from the user-side unit's display device, light, speaker, etc.

[0126] After the refrigerant recovery operation has ended, the user or maintenance personnel of the heat pump system 100 can repair the refrigerant leak point in the utilization side unit 120. Since most of the refrigerant has been vented from the utilization side piping section 102, the repair can be performed safely.

[0127] <Beneficial Effects>

[0128] As described above, the heat pump system 100 is configured to be controlled during refrigerant recovery operation such that when a predetermined valve closing condition is met during compressor 210 operation to recover refrigerant, the gas-side switching valve 460 begins to close, and the operation of compressor 210 for refrigerant recovery stops after the gas-side switching valve 460 begins to close. This prevents refrigerant recovered to the heat source side piping section 101 from flowing back to the utilization side piping section 102.

[0129] <Variation Example>

[0130] The construction and operation of the heat pump system 100 are not limited to the construction and operation described above, and / or the configuration and operation of the controller 600 are not limited to the configuration and operation described above, unless departing from the scope of the invention as defined in the appended claims. For example, some components of the heat pump system 100 and some operating steps performed by the controller 600 may be omitted.

[0131] For example, in the case of a refrigeration system, i.e., when heating operation is not required, the mode switching mechanism 220 and the heat source-side expansion mechanism 410 can be omitted. If the required performance of the heat pump system 100 is not high, the refrigerant heat exchanger 260 can be omitted. If there is no bypass pipe connected to each of the liquid refrigerant pipe 330 and the suction-side refrigerant pipe 350 and connected in parallel with the utilization-side heat exchanger 240, the storage tank 250 can be omitted. If sufficient airflow is ensured through the heat source-side heat exchanger 230 and / or the utilization-side heat exchanger 240, the heat source-side fan 231 and / or the utilization-side fan 241 can be omitted. If the heat pump system 100a is formed as a single unit, the liquid-side shut-off valve 430 and the gas-side shut-off valve 450 can be omitted.

[0132] The controller 600 can perform the determination of whether a refrigerant leak has occurred only when predetermined conditions are met. For example, the controller 600 can repeat this determination only when the compressor 210 is not operating. If the occurrence of a refrigerant leak is indicated by user operation, the refrigerant leak detector 530 can be omitted. Furthermore, refrigerant recovery operation can be triggered by other events, such as inputting an instruction to request the start of refrigerant recovery operation, regardless of whether a refrigerant leak has occurred. Steps of the controller 600 related to the omitted components can be omitted. One or more sensors that are not required for the processing of the controller 600 can be omitted.

[0133] Figure 6 This is a schematic structural diagram of a heat pump system, which is a first variation of the heat pump system 100 according to this embodiment.

[0134] like Figure 6As shown, the heat pump system 100a includes: a compressor 210; a heat source-side heat exchanger 230; a utilization-side heat exchanger 240; a storage tank 250 disposed at a location between a bypass pipe 360 ​​and the compressor 210; a discharge-side refrigerant pipe 310 connected to the heat source-side heat exchanger 230; a liquid refrigerant pipe 330; a suction-side refrigerant pipe 350 connected to the utilization-side heat exchanger 240; a bypass pipe 360; a utilization-side expansion mechanism 440; a gas-side on / off valve 460; a bypass expansion mechanism 470; an ambient temperature detector 520; and a controller 600a corresponding to a controller 600. The utilization-side expansion mechanism 440 can be disposed at a location between the heat source-side heat exchanger 230 and the bypass pipe 360. In this configuration, the discharge-side refrigerant pipe 310 corresponds to the high-pressure refrigerant pipe according to the invention, and the suction-side refrigerant pipe 350 corresponds to the low-pressure refrigerant pipe according to the invention. Furthermore, as mentioned above, the heat pump system 100a need not be included in this embodiment. Figure 1 Other components are described. Furthermore, other components can be omitted.

[0135] Figure 7 This is a schematic structural diagram of a heat pump system, which is a second variation of the heat pump system 100 according to this embodiment.

[0136] like Figure 7 As shown, compared to the first modified example, the heat pump system 100b does not have the bypass pipe 360, bypass expansion mechanism 470, and storage tank 250. Even without these components, refrigerant can be drawn from the utilization side pipe section 102 to the heat source side pipe section 101, and the drawn refrigerant can be mainly stored in the heat source side heat exchanger 230. The controller 600b of the heat pump system 100b, corresponding to the controller 600, requires fewer steps to perform.

[0137] Other variations of this embodiment are also possible. For example, the controller 600 may be set with three or more different predetermined rate of increase values ​​Rv_1, Rv_2, Rv_3, ... corresponding to different predetermined ambient temperature values ​​Ta_th1, Ta_th2, ... . The ambient temperature detector 520 can acquire the outdoor air temperature from an external device such as a weather information server via wired / wireless communication. In this case, the ambient temperature detector 520 does not need to be arranged near the heat exchanger 230 on the heat source side. If the discharge pressure is unlikely to be too high during refrigerant recovery operation, it is not necessary to change the target rate of increase value Rv_tgt according to the ambient temperature T1. In this case, the ambient temperature detector 520 can be omitted.

[0138] The refrigerant leak detector 530 can be configured to detect the occurrence of refrigerant leaks in any part of the utilization-side piping section 102. The controller 600 can be configured externally to the heat source-side piping section 101. The controller 600 can also be located away from other parts of the heat pump system 100. The fluid passing through the heat source-side heat exchanger 230 and the fluid passing through the utilization-side heat exchanger 240 can be fluids other than air, such as water. Refrigerants other than R32 can be used.

[0139] Multiple utilization-side units 120 can be connected to the heat source-side unit 110. In this case, the liquid-side switching valve 420 can be configured for each of the sub-liquid refrigerant lines branching from the liquid refrigerant line 330 to the utilization-side unit 120, and the gas-side switching valve 460 can be configured for each of the sub-gas refrigerant lines branching from the second gas refrigerant line 340 to the utilization-side unit 120. Preferably, the liquid-side switching valve 420 and the gas-side switching valve 460 are configured within or near the heat source-side unit 110. When a refrigerant leak is detected in any of the utilization-side units 120 or any of the corresponding utilization-side piping segments 102, a refrigerant recovery operation is performed. Preferably, of the liquid-side switching valve 420 and the gas-side switching valve 460, only the gas-side switching valve 460 corresponding to the utilization-side unit 120 where a refrigerant leak has occurred is opened during the refrigerant recovery operation.

[0140] Although only selected embodiments and variations of the invention have been described, it will be apparent from this disclosure to those skilled in the art that various changes and modifications can be made without departing from the scope of the invention as defined by the appended claims. For example, unless otherwise specifically stated, the size, shape, position, or orientation of various components may be varied as needed and / or desired, provided that such changes do not substantially affect their intended function. Unless otherwise specifically stated, directly connected or contacting components may have intermediate structures configured between them, provided that such changes do not substantially affect their intended function. Unless otherwise specifically stated, the function of one element may be performed by two elements, and vice versa. The structure and function of one embodiment may be employed in another embodiment. All advantages need not occur simultaneously in a particular embodiment. Therefore, the foregoing description of embodiments of the invention provided is for illustrative purposes only.

[0141] [List of reference numerals]

[0142] 100, 100a, 100b: Heat pump system;

[0143] 101: Pipeline section on the heat source side;

[0144] 102: Utilize the side pipe section;

[0145] 110: Heat source side unit;

[0146] 120: Utilizing side units;

[0147] 210: Compressor;

[0148] 220: Mode switching mechanism;

[0149] 230: Heat source side heat exchanger;

[0150] 231: Heat source side fan;

[0151] 240: Utilizing a side heat exchanger;

[0152] 241: Utilize a side fan;

[0153] 250: Storage tank;

[0154] 260: Refrigerant heat exchanger;

[0155] 310: Discharge side refrigerant pipe (high-pressure refrigerant pipe);

[0156] 320: First gas refrigerant line (high-pressure refrigerant line, low-pressure refrigerant line);

[0157] 330: Liquid refrigerant line;

[0158] 340: Second gas refrigerant pipe (low-pressure refrigerant pipe, high-pressure refrigerant pipe);

[0159] 350: Suction-side refrigerant line (low-pressure refrigerant line);

[0160] 360: Bypass pipe;

[0161] 410: Expansion mechanism on the heat source side (expansion mechanism);

[0162] 420: Liquid-side switching valve;

[0163] 430: Liquid-side shut-off valve;

[0164] 440: Utilizing a side expansion mechanism (expansion mechanism);

[0165] 450: Gas-side shut-off valve;

[0166] 460: Gas-side switching valve;

[0167] 470: Bypass expansion mechanism;

[0168] 510: Discharge-side refrigerant status detector;

[0169] 520: Ambient temperature detector;

[0170] 530: Refrigerant Leak Detector;

[0171] 540: Suction-side refrigerant status detector (evaporation temperature detector, suction pressure detector);

[0172] 600, 600a, 600b: Controller;

[0173] 610: Storage Department;

[0174] 620: Information Input Department;

[0175] 630: Normal operation controller;

[0176] 640: Information Output Department;

[0177] 650: Refrigerant recovery controller;

[0178] 651: Leak Detection Department;

[0179] 652: Temperature Detection Department;

[0180] 653: Acceleration rate switching unit;

[0181] 654: Timing Control Department.

Claims

1. A heat pump system, comprising: compressor; A heat source-side heat exchanger, the heat source-side heat exchanger being configured such that a refrigerant flowing in the heat source-side heat exchanger exchanges heat with a fluid passing through the heat source-side heat exchanger. A side heat exchanger is used, which is configured such that heat exchange occurs between the refrigerant flowing in the side heat exchanger and the fluid passing through the side heat exchanger. A high-pressure refrigerant line, which is connected to the discharge port of the compressor and each of the heat source-side heat exchangers; A liquid refrigerant pipe, the liquid refrigerant pipe being connected to each of the heat source-side heat exchanger and the utilization-side heat exchanger; A low-pressure refrigerant line, the low-pressure refrigerant line being connected to each of the utilization-side heat exchanger and the suction port of the compressor; A liquid-side switching valve, wherein the liquid-side switching valve is disposed in the liquid refrigerant line; An expansion mechanism, which is disposed in the liquid refrigerant pipe; A gas-side switching valve, wherein the gas-side switching valve is disposed in the low-pressure refrigerant line; A suction pressure detector configured to detect the pressure of the refrigerant flowing in a low-pressure refrigerant line; as well as A controller configured to operate the heat pump system by simultaneously closing the liquid-side switching valve and opening the gas-side switching valve, to perform a refrigerant recovery operation to recover refrigerant from the utilization-side piping section to the heat source-side piping section. The utilization-side piping section extends between the liquid-side switching valve and the gas-side switching valve, and includes at least the utilization-side heat exchanger. The heat source-side piping section extends between the gas-side switching valve and the liquid-side switching valve, and includes at least the compressor. in, The controller is configured to control the heat pump system in the refrigerant recovery mode such that when a predetermined valve closing condition is met during compressor operation to recover refrigerant, the gas-side switching valve begins to gradually close, and the operation of the compressor for refrigerant recovery stops after the gas-side switching valve begins to close. The predetermined valve closing condition includes a refrigerant pressure flowing in the low-pressure refrigerant line that is lower than a first predetermined suction pressure value. The controller is configured to control the compressor during the refrigerant recovery operation, such that the compressor stops operating when a predetermined compressor stop condition is met after the gas-side switching valve has begun to close. The predetermined compressor stop condition includes at least a first condition. In the first condition, the rate of change of pressure of the refrigerant flowing in the high-pressure refrigerant pipe is lower than a first predetermined rate of change value, and the rate of change of pressure of the refrigerant flowing in the low-pressure refrigerant pipe is lower than a second predetermined rate of change value that is equal to or different from the first predetermined rate of change value.

2. The heat pump system as described in claim 1, characterized in that, It also includes a refrigerant leak detector configured to detect the occurrence of a refrigerant leak in the utilization-side piping section. in, The controller is configured to control the heat pump system to perform the refrigerant recovery operation when a refrigerant leak is detected.

3. The heat pump system as described in claim 1 or 2, characterized in that, The gas-side switching valve is an electric valve.

4. The heat pump system as described in claim 1 or 2, characterized in that, At least the utilization-side heat exchanger is configured in the utilization-side unit. At least the compressor, the gas-side switching valve, and the controller are configured in a heat source-side unit that is separate from the utilization-side unit.

5. The heat pump system as described in claim 1 or 2, characterized in that, The Cv value of the gas-side switching valve is greater than the Cv value of the liquid-side switching valve.

6. The heat pump system as described in claim 1 or 2, characterized in that, Also includes: A bypass pipe is connected to the liquid refrigerant pipe at a point between the heat exchanger on the heat source side and the liquid-side switching valve, and to the low-pressure refrigerant pipe at a point between the gas-side switching valve and the compressor. A bypass expansion mechanism is disposed in the bypass pipe; as well as A storage tank is inserted into the low-pressure refrigerant line at a point between the bypass pipe and the compressor. in, The controller is configured to open the bypass expansion mechanism during the refrigerant recovery operation.

7. The heat pump system as described in claim 1 or 2, characterized in that, The controller is configured to control the heat pump system during the refrigerant recovery operation, such that the operation of the compressor used for refrigerant recovery stops after the gas-side switching valve is closed.

8. The heat pump system as described in claim 1 or 2, characterized in that, The predetermined valve closing condition also includes that the pressure of the refrigerant flowing in the low-pressure refrigerant line has been kept below the first predetermined suction pressure value for a second predetermined time.

9. A controller for controlling the operation of a heat pump system, characterized in that, The heat pump system includes: compressor; A heat source-side heat exchanger, the heat source-side heat exchanger being configured such that a refrigerant flowing in the heat source-side heat exchanger exchanges heat with a fluid passing through the heat source-side heat exchanger. A side heat exchanger is used, which is configured such that heat exchange occurs between the refrigerant flowing in the side heat exchanger and the fluid passing through the side heat exchanger. A high-pressure refrigerant line, which is connected to the discharge port of the compressor and each of the heat source-side heat exchangers; A liquid refrigerant pipe, the liquid refrigerant pipe being connected to each of the heat source-side heat exchanger and the utilization-side heat exchanger; A low-pressure refrigerant line, the low-pressure refrigerant line being connected to each of the utilization-side heat exchanger and the suction port of the compressor; A liquid-side switching valve, wherein the liquid-side switching valve is disposed in the liquid refrigerant line; An expansion mechanism, which is disposed in the liquid refrigerant pipe; A suction pressure detector configured to detect the pressure of refrigerant flowing in a low-pressure refrigerant line; and A gas-side switching valve, wherein the gas-side switching valve is disposed in the low-pressure refrigerant line. The controller is configured to, upon detecting a refrigerant leak, control the heat pump system by simultaneously operating the compressor while the liquid-side switching valve is closed and the gas-side switching valve is open, to perform a refrigerant recovery operation to recover refrigerant from the utilization-side piping section to the heat source-side piping section. The utilization-side piping section extends between the liquid-side switching valve and the gas-side switching valve, and includes at least the utilization-side heat exchanger. The heat source-side piping section extends between the gas-side switching valve and the liquid-side switching valve, and includes at least the compressor. in, The controller is configured to control the heat pump system in the refrigerant recovery mode such that when a predetermined valve closing condition is met during compressor operation to recover refrigerant, the gas-side switching valve begins to gradually close, and the operation of the compressor for refrigerant recovery stops after the gas-side switching valve begins to close. The predetermined valve closing condition includes a refrigerant pressure flowing in the low-pressure refrigerant line that is lower than a first predetermined suction pressure value. The controller is configured to control the compressor during the refrigerant recovery operation, such that the compressor stops operating when a predetermined compressor stop condition is met after the gas-side switching valve has begun to close. The predetermined compressor stop condition includes at least a first condition. In the first condition, the rate of change of pressure of the refrigerant flowing in the high-pressure refrigerant pipe is lower than a first predetermined rate of change value, and the rate of change of pressure of the refrigerant flowing in the low-pressure refrigerant pipe is lower than a second predetermined rate of change value that is equal to or different from the first predetermined rate of change value.

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