Control methods for heat pump systems, heat pump systems and storage media

Abstract

This invention discloses a control method for a heat pump system, the heat pump system itself, and a storage medium. The heat pump system includes a main refrigerant circuit and refrigerant branch circuits. The main refrigerant circuit includes a compressor, an indoor unit, an outdoor heat exchanger, and a reversing assembly. The refrigerant branch circuits include an energy storage device and a first control valve. One end of the refrigerant branch circuit is connected to the compressor's exhaust port, and the pipeline between the indoor unit and the outdoor heat exchanger is connected to the other end of the refrigerant branch circuit. The method includes: when the heat pump system is in oil return mode, controlling the first control valve to open and controlling the reversing assembly to connect the outdoor heat exchanger to the compressor's exhaust port and the indoor unit to the compressor's return port; obtaining the subcooling degree of the energy storage device; and controlling the opening degree of the first control valve based on the subcooling degree to allow compressor oil in the refrigerant branch circuit to flow back to the compressor. This invention aims to improve the oil return effect of the pipeline containing the energy storage device and avoid compressor damage due to oil shortage.

Description

Technical Field

[0001] This invention relates to the field of heat pump technology, and more particularly to a control method for a heat pump system, a heat pump system, and a storage medium. Background Technology

[0002] In addition to regulating the indoor environment, heat pump systems also include energy storage devices such as water tanks to provide energy for other needs. In some heat pump systems, the energy storage device is connected to the compressor's exhaust port. The pipeline containing the energy storage device is maintained at high pressure. After the compressor oil mixes with the refrigerant and flows into the pipeline containing the energy storage device, only a small amount is carried back to the compressor through the high-speed gaseous refrigerant. This poor oil return effect can easily lead to compressor oil shortage and damage. Summary of the Invention

[0003] The main objective of this invention is to provide a control method for a heat pump system, a heat pump system, and a storage medium, which aims to improve the oil return effect of the pipeline where the energy storage device is located and avoid damage to the compressor due to oil shortage.

[0004] To achieve the above objectives, the present invention provides a control method for a heat pump system. The heat pump system includes a main refrigerant circuit and a branch refrigerant circuit. The main refrigerant circuit includes a compressor, an indoor unit, an outdoor heat exchanger, and a reversing assembly. The branch refrigerant circuit includes an energy storage device and a first control valve. One end of the branch refrigerant circuit is connected to the exhaust port of the compressor, and the pipeline between the indoor unit and the outdoor heat exchanger is connected to the other end of the branch refrigerant circuit. The control method for the heat pump system includes the following steps:

[0005] When the heat pump system is in oil return mode, the first control valve is opened and the reversing assembly is operated to connect the outdoor heat exchanger with the exhaust port of the compressor and the indoor unit with the return port of the compressor.

[0006] Obtain the subcooling degree of the energy storage device;

[0007] The opening degree of the first control valve is controlled according to the subcooling degree so that the compressor oil in the refrigerant branch flows back to the compressor.

[0008] Optionally, the step of controlling the opening of the first control valve according to the subcooling degree to allow the compressor oil in the refrigerant branch to flow back to the compressor includes:

[0009] When the subcooling degree is less than the preset subcooling degree, the first control valve is controlled to reduce its opening degree;

[0010] When the subcooling degree is greater than the preset subcooling degree, the first control valve is controlled to increase its opening degree.

[0011] Optionally, the step of controlling the first control valve to reduce its opening degree when the subcooling degree is less than the preset subcooling degree includes:

[0012] A first opening adjustment value is determined based on the first difference between the preset subcooling and the subcooling, and the first control valve is controlled to reduce its opening based on the first opening adjustment value.

[0013] The step of controlling the first control valve to increase its opening degree when the subcooling degree is greater than the preset subcooling degree includes:

[0014] A second opening adjustment value is determined based on the second difference between the subcooling degree and the preset subcooling degree, and the first control valve is controlled to increase its opening based on the second opening adjustment value.

[0015] Optionally, the indoor unit includes an indoor heat exchanger, and the step of determining the first opening adjustment value based on the preset subcooling degree and the first difference between the subcooling degree includes:

[0016] Based on the current superheat of the indoor heat exchanger, a first target correspondence is obtained between the subcooling difference and the opening adjustment value, and the first opening adjustment value corresponding to the first difference is determined based on the first target correspondence.

[0017] And / or, the step of determining the second opening adjustment value based on the second difference between the subcooling and the preset subcooling includes:

[0018] The second target correspondence between the subcooling difference and the opening adjustment value is obtained based on the current superheat of the indoor heat exchanger, and the second opening adjustment value corresponding to the second difference is determined based on the second target correspondence.

[0019] Optionally, the indoor unit includes an indoor heat exchanger and a second control valve, and the step of controlling the opening of the first control valve according to the subcooling degree is performed simultaneously or afterward, further comprising:

[0020] Obtain the superheat of the indoor heat exchanger;

[0021] The opening degree of the second control valve is controlled according to the superheat.

[0022] Optionally, the step of controlling the opening degree of the second control valve according to the superheat includes:

[0023] When the superheat is greater than the first preset superheat, the second control valve is controlled to increase its opening.

[0024] When the superheat is less than or equal to the second preset superheat, the second control valve is controlled to reduce its opening.

[0025] Wherein, the second preset superheat is less than or equal to the first preset superheat.

[0026] Optionally, the step of obtaining the subcooling of the energy storage device includes:

[0027] The temperature of the refrigerant flowing out of the energy storage device and the condensation temperature of the heat pump system are obtained.

[0028] The subcooling degree is determined based on the temperature difference between the condensation temperature and the refrigerant temperature.

[0029] Optionally, the indoor unit includes an indoor heat exchanger and a second control valve. Before the step of controlling the first control valve to open and controlling the reversing assembly to operate so that the outdoor heat exchanger is connected to the compressor's exhaust port and the indoor unit is connected to the compressor's return port when the heat pump system is in oil return mode, the method further includes:

[0030] The first control valve is opened, the reversing assembly is operated so that both the outdoor heat exchanger and the indoor unit are connected to the return port of the compressor, and the second control valve is closed.

[0031] When the heat pump system operates to the point where the preset oil return conditions are met, the heat pump system is controlled to start the oil return mode.

[0032] In addition, to achieve the above objectives, this application also proposes a heat pump system, which includes a control device, a refrigerant main line and a refrigerant branch line. The refrigerant main line includes a compressor, an indoor unit, an outdoor heat exchanger and a reversing assembly. The refrigerant branch line includes an energy storage device and a first control valve. One end of the refrigerant branch line is connected to the exhaust port of the compressor, and the pipeline between the indoor unit and the outdoor heat exchanger is connected to the other end of the refrigerant branch line.

[0033] Both the reversing assembly and the first control valve are connected to the control device, which includes a memory, a processor, and a control program for a heat pump system stored in the memory and executable on the processor. When the control program for the heat pump system is executed by the processor, it implements the steps of the control method for the heat pump system as described in any of the preceding claims.

[0034] In addition, to achieve the above objectives, this application also proposes a storage medium storing a control program for a heat pump system, which, when executed by a processor, implements the steps of the control method for the heat pump system as described in any of the preceding claims.

[0035] This invention proposes a control method for a heat pump system. In addition to a main refrigerant circuit including a compressor, indoor unit, outdoor heat exchanger, and reversing assembly, the heat pump system also includes a refrigerant branch circuit comprising an energy storage device and a first control valve. During the oil return mode operation of the heat pump system, the reversing assembly switches the outdoor heat exchanger to a high-pressure state and the indoor unit to a low-pressure state. During this process, the opening of the first control valve is controlled according to the subcooling of the energy storage device, allowing the refrigerant branch circuit to generate a sufficient amount of liquid refrigerant to mix with the compressor oil in the branch circuit. The liquid refrigerant mixed with a large amount of compressor oil can flow through the low-pressure side of the indoor unit and then return to the compressor, thereby improving the oil return effect of the pipeline containing the energy storage device and preventing compressor damage due to oil shortage. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the refrigerant piping structure in one embodiment of the heat pump system of the present invention and a schematic diagram of the refrigerant flow direction in the first mode;

[0037] Figure 2 This is a schematic diagram of the refrigerant piping structure in one embodiment of the heat pump system of the present invention and a schematic diagram of the refrigerant flow direction in the second mode;

[0038] Figure 3 This is a schematic diagram of the refrigerant piping structure in one embodiment of the heat pump system of the present invention and a schematic diagram of the refrigerant flow direction in the third mode;

[0039] Figure 4 This is a schematic diagram of the refrigerant piping structure in one embodiment of the heat pump system of the present invention and a schematic diagram of the refrigerant flow direction in the fourth mode;

[0040] Figure 5 This is a schematic diagram of the hardware structure involved in the operation of an embodiment of the heat pump system of the present invention;

[0041] Figure 6 This is a flowchart illustrating an embodiment of the control method for the heat pump system of the present invention;

[0042] Figure 7 This is a schematic flowchart of another embodiment of the control method for the heat pump system of the present invention;

[0043] Figure 8 This is a flowchart illustrating another embodiment of the control method for the heat pump system of the present invention;

[0044] Figure 9 This is a flowchart illustrating another embodiment of the control method for the heat pump system of the present invention.

[0045] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0046] It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0047] This invention provides a heat pump system.

[0048] In this embodiment of the invention, reference is made to Figures 1 to 5 The heat pump system includes a control device 100, a main refrigerant circuit, and refrigerant branch circuits. The main refrigerant circuit includes a compressor 1, an indoor unit, an outdoor heat exchanger 3, a throttling device 4, and a reversing assembly 5. The refrigerant branch circuits include an energy storage device 7 and a first control valve 8. One end of the refrigerant branch circuit is connected to the exhaust port of the compressor 1, and the pipeline between the indoor unit and the outdoor heat exchanger 3 is connected to the other end of the refrigerant branch circuit. The indoor unit, the reversing assembly 5, the compressor 1, the throttling device 4, and the first control valve 8 are all connected to the control device 100.

[0049] In this embodiment, the energy storage device 7 includes a water tank. In other embodiments, the energy storage device 7 may also include other types of devices with energy storage functions. When the refrigerant in the refrigerant branch flows through the energy storage device 7, it can exchange heat with the energy storage material therein, and the energy storage material can absorb and store the energy flowing through the refrigerant.

[0050] In this embodiment, there is one indoor unit. In other embodiments, there may be more than one indoor unit, and the more than one indoor unit can be connected in parallel.

[0051] The indoor unit includes an indoor heat exchanger 21 and a second control valve 22 connected in series with the indoor heat exchanger 21. The second control valve 22 is connected to a control device 100, which can be used to control the refrigerant flow through the indoor heat exchanger 21.

[0052] The indoor unit, throttling device 4, and outdoor heat exchanger 3 are connected in sequence. The pipe between the throttling device 4 and the indoor unit is connected to one end of the refrigerant branch. The exhaust port of the indoor unit, outdoor heat exchanger 3, and compressor 1, as well as the return port of compressor 1, are all connected to the reversing assembly 5. The reversing assembly 5 can be used to switch the connection status between the indoor unit and outdoor heat exchanger 3 and the exhaust port and return port of compressor 1.

[0053] In this embodiment, the reversing assembly 5 includes a first reversing valve 51 and a second reversing valve 52. The exhaust port of the compressor 1, the return port of the compressor 1, and the indoor unit are respectively connected to different valve ports of the first reversing valve 51, and the exhaust port of the compressor 1, the return port of the compressor 1, and the outdoor heat exchanger 3 are respectively connected to different valve ports of the second reversing valve 52. In one implementation of this embodiment, the first reversing valve 51 is a first four-way valve, and the second reversing valve 52 is a second four-way valve. In another implementation of this embodiment, the first reversing valve 51 is a first three-way valve, and the second reversing valve 52 is a second three-way valve.

[0054] The first reversing valve 51 has a first valve position and a second valve position. In the first valve position, the return port of the compressor 1 is connected to the indoor heat exchanger 21, and the exhaust port of the compressor 1 is blocked from the indoor heat exchanger 21. In the second valve position, the return port of the compressor 1 is blocked from the indoor heat exchanger 21, and the exhaust port of the compressor 1 is connected to the indoor heat exchanger 21.

[0055] The second reversing valve 52 has a third valve position and a fourth valve position. In the third valve position, the exhaust port of the compressor 1 is connected to the outdoor heat exchanger 3, and the return port of the compressor 1 is blocked from the outdoor heat exchanger 3. In the fourth valve position, the exhaust port of the compressor 1 is blocked from the outdoor heat exchanger 3, and the return port of the compressor 1 is connected to the outdoor heat exchanger 3.

[0056] Through the adjustment of the first reversing valve 51, the second reversing valve 52, the first control valve 8, and the second control valve 22, the operating modes of the heat pump system include, but are not limited to, the following modes:

[0057] In the first mode, refer to Figure 1 The first reversing valve 51 operates in the first valve position, the second reversing valve 52 operates in the fourth valve position, the second control valve 22 is closed, and the first control valve 8 is open. All the refrigerant discharged from the compressor 1 flows into the refrigerant branch. The refrigerant flowing into the refrigerant branch stores heat in the energy storage device 7 as it flows through the energy storage device 7. The refrigerant flowing out of the refrigerant branch flows through the throttling device 4 and the outdoor heat exchanger 3 in sequence before returning to the compressor 1. In the first mode, the indoor heat exchanger 21 stops exchanging heat, and the outdoor heat exchanger 3 is in an evaporating state. All heat is used for heat storage in the energy storage device 7. In the first mode, the energy storage device 7 can store heat independently.

[0058] In the second mode, refer to Figure 2In the first reversing valve 51, the first reversing valve 52 operates in the first valve position; the second reversing valve 52 operates in the third valve position; the first control valve 8 is open; and the second control valve 22 is open. A portion of the refrigerant discharged from the compressor 1 flows sequentially through the outdoor heat exchanger 3 and the throttling device 4. Another portion of the refrigerant discharged from the compressor 1 flows into the refrigerant branch. The refrigerant flowing into the refrigerant branch stores heat in the energy storage device 7 as it passes through the energy storage device 7. The refrigerant flowing out of the refrigerant branch merges with the refrigerant flowing out of the throttling device 4 and flows into the indoor unit for evaporation before returning to the compressor 1. In the second mode, the indoor heat exchanger 21 is in an evaporating state, and the outdoor heat exchanger 3 is in a condensing state. In the second mode, when the indoor space regulated by the indoor unit has a heat exchange requirement, the indoor fan in the indoor unit can be turned on to drive the indoor air to exchange heat with the indoor heat exchanger 21; when the indoor space regulated by the indoor unit does not have a heat exchange requirement, the indoor fan in the indoor unit can be turned off. In the second mode, the heat absorbed by the outdoor heat exchanger 3 from its environment can be stored in the energy storage device 7. In the second mode, the energy storage device 7 can store heat during the cooling process of the indoor environment, or the oil in the compressor 1 in the refrigerant branch can be returned to the compressor 1 while the energy storage device 7 stores heat.

[0059] In the third mode, refer to Figure 3 The first reversing valve 51 operates in the first valve position, the second reversing valve 52 operates in the fourth valve position, the first control valve 8 is open, and the second control valve 22 operates in a throttling mode. All the refrigerant discharged from the compressor 1 flows into the refrigerant branch. When the refrigerant flowing into the refrigerant branch passes through the energy storage device 7, heat is stored in the energy storage device 7. A portion of the refrigerant flowing out of the refrigerant branch flows through the throttling device 4 and the outdoor heat exchanger 3 in sequence before returning to the compressor 1. Another portion of the refrigerant flowing out of the refrigerant branch flows through the second control valve 22 and the indoor heat exchanger 21 in sequence before returning to the compressor 1. In the third mode, both the indoor heat exchanger 21 and the outdoor heat exchanger 3 are in an evaporating state. In the third mode, when the indoor space regulated by the indoor unit has a heat exchange requirement, the indoor fan in the indoor unit can be turned on to drive the indoor air to exchange heat with the indoor heat exchanger 21; when the indoor space regulated by the indoor unit does not have a heat exchange requirement, the indoor fan in the indoor unit can be turned off. In the third mode, the heat absorbed by both the indoor heat exchanger 21 and the outdoor heat exchanger 3 from their respective environments can be stored in the energy storage device 7. In the third mode, the indoor environment can be cooled while the energy storage device 7 stores heat.

[0060] In the fourth mode, refer to Figure 4In the fourth mode, the first reversing valve 51 operates in the first valve position, the second reversing valve 52 operates in the third valve position, the first control valve 8 is closed, and the second control valve 22 is open. The refrigerant discharged from the compressor 1 flows sequentially through the outdoor heat exchanger 3, the throttling device 4, the second control valve 22, and the indoor heat exchanger 21 before returning to the compressor 1. In this mode, the indoor heat exchanger 21 is in an evaporating state, and the outdoor heat exchanger 3 is in a condensing state. In the fourth mode, when the indoor space regulated by the indoor unit has a heat exchange requirement, the indoor fan in the indoor unit can be turned on to drive the indoor air to exchange heat with the indoor heat exchanger 21; when the indoor space regulated by the indoor unit does not have a heat exchange requirement, the indoor fan in the indoor unit can be turned off. In the fourth mode, the indoor environment can be cooled while the energy storage device 7 stops storing heat.

[0061] In other embodiments, the reversing assembly 5 may also include a third four-way valve, with the exhaust port of the compressor 1, the return port of the compressor 1, the indoor heat exchanger 21 and the outdoor heat exchanger 3 respectively connected to different ports of the third four-way valve.

[0062] Furthermore, refer to Figures 1 to 5 The heat pump system also includes a pressure sensor 01, which can be located on the exhaust side of the compressor 1 to detect the condensing pressure of the heat pump system. The pressure sensor 01 is connected to the control device 100.

[0063] Furthermore, refer to Figure 5 The heat pump system also includes a temperature detection module 02, which is connected to the control device 100. The temperature detection module 02 includes a first temperature sensor located at the refrigerant outlet of the energy storage device 7 to detect the temperature of the refrigerant flowing out of the energy storage device 7. The temperature detection module 02 may also include a second temperature sensor and a third temperature sensor, respectively located at both ends of the indoor heat exchanger 21 to detect the inlet temperature and outlet temperature of the indoor heat exchanger 21.

[0064] In this embodiment of the invention, reference is made to Figure 5 The control device 100 of the heat pump system includes a processor 1001, such as a CPU, a memory 1002, and a timer 1003. These components communicate with each other via a communication bus. The memory 1002 can be a high-speed RAM or a stable, non-volatile memory, such as a disk drive. Optionally, the memory 1002 can also be a storage device independent of the aforementioned processor 1001.

[0065] Those skilled in the art will understand that Figure 5 The device structure shown does not constitute a limitation on the device and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0066] like Figure 5 As shown, the memory 1002, which serves as a computer storage medium, may include a control program for a heat pump system.

[0067] exist Figure 5 In the device shown, the processor 1001 can be used to call the control program of the heat pump system stored in the memory 1002 and execute the relevant steps of the control method of the heat pump system in the following embodiments.

[0068] This invention also provides a control method for a heat pump system, applied to the aforementioned heat pump system.

[0069] Reference Figure 6 This application proposes an embodiment of a control method for a heat pump system. In this embodiment, the control method for the heat pump system includes:

[0070] Step S10: When the heat pump system is in oil return mode, control the first control valve to open and control the reversing assembly to connect the outdoor heat exchanger with the exhaust port of the compressor and the indoor unit with the return port of the compressor.

[0071] The oil return mode can be activated when the heat pump system is detected to be operating under oil return conditions, or when a preset command is received manually.

[0072] When the outdoor heat exchanger is connected to the compressor's exhaust port, the outdoor heat exchanger is under high pressure; when the indoor unit is connected to the compressor's return port, the indoor unit is under low pressure.

[0073] The first control valve can be opened at a preset initial opening degree (such as the maximum opening degree) or at an initial opening degree determined according to the actual operating conditions of the heat pump system.

[0074] In oil return mode, the first reversing valve is controlled to operate at the first valve position, the second reversing valve is controlled to operate at the third valve position, the first control valve is controlled to open, and the second control valve is controlled to open. A portion of the refrigerant discharged from the compressor flows sequentially through the outdoor heat exchanger and the throttling device, while the other portion of the refrigerant discharged from the compressor flows into the refrigerant branch. The refrigerant flowing into the refrigerant branch stores heat in the energy storage device as it flows through it. The refrigerant flowing out of the refrigerant branch merges with the refrigerant flowing out of the throttling device and flows into the indoor unit for evaporation before returning to the compressor. In oil return mode, the indoor heat exchanger is in an evaporating state, and the outdoor heat exchanger is in a condensing state.

[0075] Step S20: Obtain the subcooling degree of the energy storage device;

[0076] Subcooling can accurately reflect the condensation effect during the heat storage process of an energy storage device.

[0077] The degree of subcooling can be determined by temperature detection data related to the energy storage device, or by pressure detection data related to the energy storage device.

[0078] Step S30: Control the opening of the first control valve according to the subcooling degree so that the compressor oil in the refrigerant branch flows back to the compressor.

[0079] Compressor oil can be used to lubricate compressors and reduce wear during compressor operation.

[0080] In one implementation, the opening adjustment parameter can be determined based on the subcooling, and the opening of the first control valve can be adjusted according to the opening adjustment parameter. In another implementation, the target opening of the first control valve can be determined based on the subcooling, and the first control valve can be controlled to operate at the target opening.

[0081] When the amount of liquid refrigerant is the same as the amount of gaseous refrigerant, the amount of compressor oil mixed with the liquid refrigerant is greater than the amount mixed with the gaseous refrigerant. Based on this, when the opening degree of the first control valve is adapted to control the subcooling, the amount of liquid refrigerant in the refrigerant branch can be adjusted to ensure that there is enough liquid refrigerant to mix with the compressor oil in the refrigerant branch, thus preventing compressor oil from accumulating in the refrigerant branch.

[0082] This invention discloses a control method for a heat pump system. Besides a main refrigerant circuit including a compressor, indoor unit, outdoor heat exchanger, and reversing assembly, the system also includes a refrigerant branch circuit comprising an energy storage device and a first control valve. One end of the refrigerant branch circuit is directly connected to the exhaust port of the compressor, ensuring the energy storage device is always connected to high-speed gaseous refrigerant and operates at a high pressure. During the oil return mode operation of the heat pump system, the reversing assembly switches the outdoor heat exchanger to a high-pressure state and the indoor unit to a low-pressure state. In this process, the opening of the first control valve is controlled according to the subcooling of the energy storage device, allowing the refrigerant branch circuit (energy storage device) to generate a sufficient amount of liquid refrigerant to mix with the compressor oil in the branch circuit. The liquid refrigerant mixed with a large amount of compressor oil flows through the low-pressure side of the indoor unit and then returns to the compressor, thereby improving the oil return effect of the pipeline containing the energy storage device and preventing compressor damage due to oil shortage.

[0083] Furthermore, in this embodiment, step S20 includes: obtaining the temperature of the refrigerant flowing out of the energy storage device and the condensation temperature of the heat pump system, and determining the subcooling degree based on the temperature difference between the condensation temperature and the refrigerant temperature.

[0084] The refrigerant temperature can be detected by the aforementioned first temperature sensor.

[0085] In this embodiment, the condensing temperature can be calculated from the pressure detected by the aforementioned pressure sensor. In other embodiments, the condensing temperature can also be detected by a temperature sensor installed on the compressor exhaust side.

[0086] In this embodiment, the temperature difference is determined to be the subcooling. In other embodiments, it can also be determined based on the actual state parameters of the heat pump system.

[0087] In this embodiment, determining the subcooling in the above manner helps to improve the accuracy of the subcooling in representing the actual amount of liquid refrigerant in the refrigerant branch. It ensures that after adjusting the opening of the first control valve according to the subcooling, there is enough refrigerant in the refrigerant branch to carry away the compressor oil in the refrigerant branch and return it to the compressor, further improving the oil return effect of the pipeline where the energy storage device is located and avoiding damage to the compressor due to lack of oil.

[0088] Furthermore, based on the above embodiments, another embodiment of the control method for the heat pump system of this application is proposed. In this embodiment, reference is made to... Figure 7 Step S30 includes:

[0089] Step S31: When the subcooling degree is less than the preset subcooling degree, control the first control valve to reduce its opening degree.

[0090] The preset subcooling is the maximum subcooling of the energy storage device that is allowed when the system is operating reliably and the oil return effect is good.

[0091] During the process of reducing the opening degree of the first control valve, it can be reduced according to a pre-set fixed opening degree adjustment value, or it can be reduced according to the opening degree adjustment value determined by the actual operating state of the heat pump system.

[0092] Step S32: When the subcooling degree is greater than the preset subcooling degree, control the first control valve to increase its opening degree.

[0093] During the process of increasing the opening degree of the first control valve, it can be increased according to the preset fixed opening degree adjustment value, or it can be increased according to the opening degree adjustment value determined by the actual operating state of the heat pump system.

[0094] In this embodiment, when the subcooling is less than the preset subcooling, it indicates that the amount of liquid refrigerant in the refrigerant branch is insufficient. At this time, controlling the first control valve to reduce the opening is beneficial to increasing the amount of liquid refrigerant in the refrigerant branch, ensuring that there is enough liquid refrigerant to carry the compressor oil back to the compressor, thereby effectively improving the oil return effect of the refrigerant branch. When the subcooling is greater than the preset subcooling, it indicates that the amount of liquid refrigerant in the refrigerant branch is sufficient, but the system is prone to reliability problems if the superheat is too high. At this time, controlling the first control valve to increase the opening is beneficial to ensuring the oil return effect while improving the reliability of compressor operation.

[0095] Furthermore, in this embodiment, the step of controlling the first control valve to reduce its opening when the subcooling degree is less than the preset subcooling degree includes: determining a first opening adjustment value based on a first difference between the preset subcooling degree and the subcooling degree, and controlling the first control valve to reduce its opening degree based on the first opening adjustment value.

[0096] The first difference is the calculated result obtained by subtracting the subcooling from the preset subcooling. In this embodiment, the first difference is positively correlated with the first opening adjustment value.

[0097] In one implementation of this embodiment, the correspondence between the first difference and the first opening adjustment value can be a pre-set fixed relationship. The correspondence can include a calculation formula, a mapping relationship, etc. Based on the correspondence, the first opening adjustment value can be calculated by substituting the first difference into the formula. Alternatively, the interval in which the first difference is located can be determined, and the opening adjustment value that has a mapping relationship with the interval can be used as the first opening adjustment value.

[0098] In another implementation of this embodiment, a first target correspondence between the subcooling difference and the opening adjustment value is obtained based on the current superheat of the indoor heat exchanger. The first opening adjustment value corresponding to the first difference is then determined based on this first target correspondence. Different superheats can correspond to different first target correspondences. The numerical range of the superheat can be determined, and a preset correspondence between the difference associated with this numerical range and the opening adjustment value is used as the first target correspondence. The first target correspondence may include calculation formulas, mapping relationships, etc. Based on this first target relationship, the first opening adjustment value can be obtained through calculation, table lookup, etc.

[0099] In this embodiment, the above method helps ensure that the subcooling of the refrigerant branch can accurately reach the preset subcooling after the opening of the first control valve is reduced, thereby further improving the oil return effect. Specifically, determining the first opening adjustment value corresponding to the first difference based on the superheat of the indoor heat exchanger helps ensure that the opening adjustment of the first control valve matches the actual evaporation effect of the indoor heat exchanger. This ensures that the refrigerant mixed with compressor oil flowing out of the refrigerant branch can carry as much compressor oil as possible back to the compressor after evaporation in the indoor heat exchanger, thereby further improving the oil return effect of the compressor oil in the refrigerant branch.

[0100] Furthermore, in this embodiment, the step of controlling the first control valve to increase its opening degree when the subcooling degree is greater than the preset subcooling degree includes: determining a second opening degree adjustment value based on a second difference between the subcooling degree and the preset subcooling degree, and controlling the first control valve to increase its opening degree based on the second opening degree adjustment value.

[0101] The second difference is the calculated result obtained by subtracting the preset subcooling from the subcooling. In this embodiment, the second difference is positively correlated with the second opening adjustment value.

[0102] In one implementation of this embodiment, the correspondence between the second difference and the second opening adjustment value can be a pre-set fixed relationship. The correspondence can include a calculation formula, a mapping relationship, etc. Based on this correspondence, the second opening adjustment value can be calculated by substituting the second difference into the formula. Alternatively, the interval in which the second difference is located can be determined, and the opening adjustment value that has a mapping relationship with the interval can be used as the second opening adjustment value.

[0103] In another implementation of this embodiment, a second target correspondence is obtained between the difference between the superheat and the subcooling value and the opening adjustment value based on the current superheat of the indoor heat exchanger. The second opening adjustment value corresponding to the second difference is then determined based on this second target correspondence. Different superheats can correspond to different second target correspondences. The numerical range of the superheat can be determined, and a preset correspondence between the difference associated with this numerical range and the opening adjustment value is used as the second target correspondence. The second target correspondence may include calculation formulas, mapping relationships, etc. Based on this second target relationship, the second opening adjustment value can be obtained through calculation, table lookup, etc.

[0104] In this embodiment, the above method helps ensure that the subcooling of the refrigerant branch can accurately reach the preset subcooling after the opening of the first control valve is increased, thereby further improving the oil return effect. Specifically, determining the second opening adjustment value corresponding to the second difference based on the corresponding second target relationship of the indoor heat exchanger helps ensure that the opening adjustment of the first control valve matches the actual evaporation effect of the indoor heat exchanger. This ensures that the refrigerant mixed with compressor oil flowing out of the refrigerant branch can carry as much compressor oil as possible back to the compressor after evaporation in the indoor heat exchanger, thereby further improving the oil return effect of the compressor oil in the refrigerant branch.

[0105] Furthermore, based on any of the above embodiments, another embodiment of the control method for the heat pump system of this application is proposed. In this embodiment, reference is made to... Figure 8 The step of controlling the opening degree of the first control valve according to the subcooling degree is performed simultaneously or after the following steps:

[0106] Step S40: Obtain the superheat of the indoor heat exchanger;

[0107] In this embodiment, the inlet and outlet temperatures of the indoor heat exchanger are detected by the second and third temperature sensors, and the superheat of the indoor heat exchanger is determined based on the temperature difference obtained by subtracting the inlet temperature from the outlet temperature.

[0108] In other embodiments, the superheat of the indoor heat exchanger can also be determined using pressure detection data related to the indoor heat exchanger.

[0109] Step S50: Control the opening degree of the second control valve according to the superheat.

[0110] In one implementation, the opening adjustment parameter can be determined based on the superheat, and the second control valve can be controlled to adjust its opening according to this parameter. In another implementation, the target opening of the second control valve can be determined based on the superheat, and the second control valve can be controlled to operate at this target opening.

[0111] In this embodiment, while controlling the opening of the first control valve according to the subcooling, the opening of the second control valve is controlled according to the superheat of the indoor heat exchanger. This helps to effectively improve the evaporation effect of the indoor heat exchanger, thereby ensuring that the refrigerant mixed with compressor oil flowing out of the refrigerant branch can be completely returned to the compressor after passing through the second control valve and the indoor heat exchanger, thereby further improving the oil return effect of the compressor oil in the refrigerant branch.

[0112] Furthermore, in this embodiment, step S50 includes: when the superheat is greater than the first preset superheat, controlling the second control valve to increase its opening; when the superheat is less than or equal to the second preset superheat, controlling the second control valve to decrease its opening; wherein the second preset superheat is less than or equal to the first preset superheat.

[0113] In this embodiment, the second preset superheat is less than the first preset superheat. The first and second preset superheats are used as threshold values ​​to form a preset superheat range. This preset superheat range characterizes the target superheat range required for the indoor heat exchanger to achieve the desired evaporation effect, ensuring that all compressor oil flowing through the refrigerant returns to the compressor while the system operates reliably. In other embodiments, the second preset superheat is equal to the first preset superheat. Either the second or first preset superheat characterizes the target superheat required for the indoor heat exchanger to achieve the desired evaporation effect, ensuring that all compressor oil flowing through the refrigerant returns to the compressor while the system operates reliably.

[0114] During the process of reducing the opening degree of the second control valve, it can be reduced according to a pre-set fixed opening degree adjustment value, or it can be reduced according to the opening degree adjustment value determined by the actual operating state of the heat pump system.

[0115] During the process of increasing the opening degree of the second control valve, it can be increased according to the preset fixed opening degree adjustment value, or it can be increased according to the opening degree adjustment value determined by the actual operating state of the heat pump system.

[0116] When the superheat is greater than a first preset superheat, the step of controlling the second control valve to increase its opening includes: determining a third opening adjustment value based on a third difference between the superheat and the first preset superheat, and controlling the second control valve to increase its opening based on the third opening adjustment value. The third difference is a calculation result obtained by subtracting the first preset superheat from the superheat. In this embodiment, the third difference is positively correlated with the third opening adjustment value.

[0117] When the superheat is less than or equal to the second preset superheat, the step of controlling the second control valve to reduce its opening includes: determining a fourth opening adjustment value based on a fourth difference between the second preset superheat and the superheat, and controlling the second control valve to reduce its opening based on the fourth opening adjustment value. The fourth difference is a calculation result obtained by subtracting the superheat from the second preset superheat. In this embodiment, the fourth difference is positively correlated with the fourth opening adjustment value.

[0118] In this embodiment, when the superheat is less than or equal to the second preset superheat, it indicates that the evaporation effect of the indoor heat exchanger is poor. At this time, controlling the second control valve to reduce the opening degree helps to increase the superheat, thereby improving the evaporation effect of the indoor heat exchanger and ensuring that there is enough liquid refrigerant to carry the compressor oil back to the compressor, thus effectively improving the oil return effect of the refrigerant branch. When the superheat is greater than the first preset superheat, it indicates that the evaporation effect of the indoor heat exchanger is better and there is enough liquid refrigerant to carry the compressor oil back to the compressor. However, if the superheat is too high, the system is prone to reliability problems. At this time, controlling the second control valve to increase the opening degree helps to reduce the superheat, ensuring the oil return effect while improving the reliability of compressor operation.

[0119] Furthermore, based on any of the above embodiments, another embodiment of the control method for the heat pump system of this application is proposed. In this embodiment, reference is made to... Figure 9 Before step S10, the procedure further includes:

[0120] Step S01: Control the first control valve to open, control the reversing assembly to operate so that both the outdoor heat exchanger and the indoor unit are connected to the return port of the compressor, and control the second control valve to close.

[0121] When the first control valve is open, and both the indoor unit and the outdoor heat exchanger are connected to the compressor's return port, all the refrigerant discharged by the compressor can flow through the energy storage device for heat storage.

[0122] In this embodiment, when the heat pump system starts the standalone heat storage mode (i.e., the first mode mentioned above), the first reversing valve is controlled to operate at the first valve position, the second reversing valve is controlled to operate at the fourth valve position, the second control valve is controlled to close, and the first control valve is controlled to open. All the refrigerant discharged from the compressor flows into the refrigerant branch. The heat of the refrigerant flowing into the refrigerant branch is stored in the energy storage device as it flows through the energy storage device. The refrigerant flowing out of the refrigerant branch flows through the throttling device and the outdoor heat exchanger in sequence before returning to the compressor. In the heat storage mode, the indoor heat exchanger stops exchanging heat, and the outdoor heat exchanger is in an evaporation state. All the heat is used for heat storage in the energy storage device.

[0123] In this embodiment, the first control valve is opened at its maximum opening degree. In other embodiments, the first control valve may also be opened at other opening degrees smaller than the maximum opening degree.

[0124] Step S02: When the heat pump system operates to the point where the preset oil return conditions are met, control the heat pump system to start the oil return mode.

[0125] During the processes of the first control valve opening, the reversing assembly operating to connect both the outdoor heat exchanger and the indoor unit to the compressor's return port, and the second control valve closing, the status parameters of the heat pump system (e.g., compressor operating frequency) are monitored. If the status parameters meet the preset oil return conditions, the heat pump system is controlled to start the oil return mode, and step S10 is executed as described above. If the status parameters do not meet the preset oil return conditions, the heat pump system can be controlled to maintain its current operation.

[0126] In this embodiment, in the standalone heat storage mode, all the refrigerant discharged from the heat pump system flows into the refrigerant branch. The compressor oil is easily discharged into the refrigerant branch along with the refrigerant and accumulates in the refrigerant branch, which poses a significant risk of compressor oil shortage. At this time, when the heat pump system is detected to meet the oil return conditions, the oil return mode is activated, which helps to improve the timeliness of oil return in the refrigerant branch, thereby further reducing the risk of compressor damage due to oil shortage in the standalone heat storage mode.

[0127] Furthermore, embodiments of the present invention also propose a storage medium storing a control program for a heat pump system. When the control program for the heat pump system is executed by a processor, it implements the relevant steps of any embodiment of the control method for the heat pump system described above.

[0128] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or system. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or system that includes that element.

[0129] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0130] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, and includes several instructions to cause a terminal device (which may be a mobile phone, computer, server, heat pump system, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0131] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A control method for a heat pump system, characterized in that, The heat pump system includes a main refrigerant circuit and a branch refrigerant circuit. The main refrigerant circuit includes a compressor, an indoor unit, a throttling device, an outdoor heat exchanger, and a reversing assembly. The branch refrigerant circuit includes a series-connected energy storage device and a first control valve. One end of the branch refrigerant circuit is connected to the exhaust port of the compressor, and the pipeline between the indoor unit and the outdoor heat exchanger is connected to the other end of the branch refrigerant circuit. The indoor unit includes an indoor heat exchanger. The control method of the heat pump system includes the following steps: When the heat pump system is in oil return mode, the first control valve is opened and the reversing assembly is operated to connect the outdoor heat exchanger with the exhaust port of the compressor and the indoor unit with the return port of the compressor. Obtain the subcooling degree of the energy storage device; When the subcooling is less than the preset subcooling, a first target correspondence between the subcooling difference and the opening adjustment value is obtained based on the current superheat of the indoor heat exchanger. Based on the first target correspondence, the first opening adjustment value corresponding to the first difference between the preset subcooling and the subcooling is determined by calculation or table lookup. Based on the first opening adjustment value, the first control valve is controlled to reduce its opening. When the subcooling degree is greater than the preset subcooling degree, a second target correspondence between the subcooling degree difference and the opening adjustment value is obtained based on the current superheat of the indoor heat exchanger. Based on the second target correspondence, the second opening adjustment value corresponding to the second difference between the subcooling degree and the preset subcooling degree is determined by calculation or table lookup. Based on the second opening adjustment value, the first control valve is controlled to increase its opening. In the oil return mode, a portion of the refrigerant discharged from the compressor flows sequentially through the outdoor heat exchanger and the throttling device, while another portion of the refrigerant discharged from the compressor flows into the refrigerant branch. When the refrigerant flowing into the refrigerant branch passes through the energy storage device, heat is stored in the energy storage device. The refrigerant flowing out of the refrigerant branch merges with the refrigerant flowing out of the throttling device and flows into the indoor unit, evaporates, and then flows back to the compressor.

2. The control method for a heat pump system as described in claim 1, characterized in that, The indoor unit also includes a second control valve, and after the step of obtaining the subcooling degree of the energy storage device, it further includes: Obtain the superheat of the indoor heat exchanger; The opening degree of the second control valve is controlled according to the superheat.

3. The control method for a heat pump system as described in claim 2, characterized in that, The step of controlling the opening degree of the second control valve based on the superheat includes: When the superheat is greater than the first preset superheat, the second control valve is controlled to increase its opening. When the superheat is less than or equal to the second preset superheat, the second control valve is controlled to reduce its opening. Wherein, the second preset superheat is less than or equal to the first preset superheat.

4. The control method for a heat pump system as described in claim 1, characterized in that, The step of obtaining the subcooling degree of the energy storage device includes: The temperature of the refrigerant flowing out of the energy storage device and the condensation temperature of the heat pump system are obtained. The subcooling degree is determined based on the temperature difference between the condensation temperature and the refrigerant temperature.

5. The control method for a heat pump system as described in any one of claims 1 to 4, characterized in that, The indoor unit further includes a second control valve. Before the step of controlling the first control valve to open and controlling the reversing assembly to operate so that the outdoor heat exchanger is connected to the compressor's exhaust port and the indoor unit is connected to the compressor's return port when the heat pump system is in oil return mode, the method further includes: The first control valve is opened, the reversing assembly is operated so that both the outdoor heat exchanger and the indoor unit are connected to the return port of the compressor, and the second control valve is closed. When the heat pump system operates to the point where the preset oil return conditions are met, the heat pump system is controlled to start the oil return mode.

6. A heat pump system, characterized in that, The heat pump system includes a control device, a refrigerant main line and refrigerant branch lines. The refrigerant main line includes a compressor, an indoor unit, a throttling device, an outdoor heat exchanger and a reversing assembly. The refrigerant branch lines include an energy storage device and a first control valve connected in series. One end of the refrigerant branch line is connected to the exhaust port of the compressor. The pipeline between the indoor unit and the outdoor heat exchanger is connected to the other end of the refrigerant branch line. The indoor unit includes an indoor heat exchanger. Both the reversing assembly and the first control valve are connected to the control device, which includes a memory, a processor, and a control program for a heat pump system stored in the memory and executable on the processor. When the control program for the heat pump system is executed by the processor, it implements the steps of the control method for the heat pump system as described in any one of claims 1 to 5.

7. A storage medium, characterized in that, The storage medium stores a control program for a heat pump system, which, when executed by a processor, implements the steps of the control method for a heat pump system as described in any one of claims 1 to 5.

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