Control method of heat pump system, heat pump system and storage medium

Abstract

The invention discloses a control method of a heat pump system, the heat pump system and a storage medium. The heat pump system comprises a refrigerant main path and a refrigerant branch path, the refrigerant main path comprises a compressor, an indoor unit, an outdoor heat exchanger and a reversing assembly, the refrigerant branch path comprises an energy storage device and a first control valve, one end of the refrigerant branch path communicates with an exhaust port of the compressor, and a pipeline between the indoor unit and the outdoor heat exchanger communicates with the other end of the refrigerant branch path; the method comprises the steps that when the heat pump system is in an oil return mode, a first control valve is controlled to be opened, and a reversing assembly is controlled to operate, so that an outdoor heat exchanger communicates with an exhaust port of a compressor, and an indoor unit communicates with an air return port of the compressor; the supercooling degree of the energy storage device is obtained; and the opening degree of the first control valve is controlled according to the supercooling degree, so that compressor oil in the refrigerant branch flows back to the compressor. The oil return effect of the pipeline where the energy storage device is located is improved, and the compressor is prevented from being damaged due to oil shortage.

Description

Technical Field

[0001] The present invention relates to the technical field of heat pumps, and in particular to a control method for a heat pump system, a heat pump system and a storage medium. Background Art

[0002] In addition to using energy to regulate the indoor environment, heat pump systems also have energy storage devices such as water tanks to provide the energy required for other needs. Among them, the energy storage device of some heat pump systems will be connected to the exhaust port of the compressor. The pipeline where the energy storage device is located is maintained at a high pressure state. After the compressor oil and refrigerant are mixed and flow into the pipeline where the energy storage device is located, only a small amount is brought back to the compressor through the high-speed gaseous refrigerant. The oil return effect is poor, which can easily lead to oil shortage and damage to the compressor. Summary of the invention

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

[0004] To achieve the above object, the present invention provides a control method for a heat pump system, the heat pump system comprising a refrigerant main circuit and a refrigerant branch circuit, the refrigerant main circuit comprising a compressor, an indoor unit, an outdoor heat exchanger and a reversing assembly, the refrigerant branch circuit comprising an energy storage device and a first control valve, one end of the refrigerant branch 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 refrigerant branch circuit, the control method of the heat pump system comprises the following steps:

[0005] When the heat pump system is in the oil return mode, the first control valve is controlled to open and the reversing assembly is controlled to operate so that the outdoor heat exchanger is connected to the exhaust port of the compressor, and the indoor unit is connected to the return port of the compressor;

[0006] Obtaining a degree of supercooling 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 circuit flows back to the compressor.

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

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

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

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

[0012] Determining a first opening adjustment value according to a first difference between the preset subcooling degree and the subcooling degree, and controlling the first control valve to reduce the opening according to the first opening adjustment value;

[0013] When the degree of subcooling is greater than the preset degree of subcooling, the step of controlling the first control valve to increase its opening degree comprises:

[0014] A second opening adjustment value is determined according to a second difference between the subcooling degree and the preset subcooling degree, and the first control valve is controlled to increase its opening according to 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 according to the first difference between the preset supercooling degree and the supercooling degree includes:

[0016] Acquire a first target correspondence between a subcooling degree difference and an opening adjustment value according to the current superheat of the indoor heat exchanger, and determine the first opening adjustment value corresponding to the first difference according to the first target correspondence;

[0017] And / or, the step of determining the second opening adjustment value according to a second difference between the supercooling degree and the preset supercooling degree includes:

[0018] A second target correspondence between a subcooling degree difference and an opening adjustment value is obtained according to the current superheat of the indoor heat exchanger, and the second opening adjustment value corresponding to the second difference is determined according to the second target correspondence.

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

[0020] Obtaining a superheat degree of the indoor heat exchanger;

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

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

[0023] When the superheat is greater than a first preset superheat, controlling the second control valve to increase its opening;

[0024] When the superheat is less than or equal to a second preset superheat, controlling the second control valve to reduce the opening degree;

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

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

[0027] Obtaining the refrigerant temperature flowing out of the energy storage device and the condensing temperature of the heat pump system;

[0028] The degree of subcooling is determined according to a temperature difference between the condensing 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 exhaust port of the compressor and the indoor unit is connected to the return air port of the compressor when the heat pump system is in the oil return mode, the step further includes:

[0030] Controlling the first control valve to open, controlling the reversing assembly to operate so that the outdoor heat exchanger and the indoor unit are both connected to the return air port of the compressor, and controlling the second control valve to close;

[0031] When the heat pump system runs to meet a preset oil return condition, the heat pump system is controlled to start an oil return mode.

[0032] In addition, in order to achieve the above-mentioned purpose, the present application also proposes a heat pump system, the heat pump system includes a control device, a refrigerant main circuit and a refrigerant branch circuit, the refrigerant main circuit includes a compressor, an indoor unit, an outdoor heat exchanger and a reversing component, the refrigerant branch circuit includes an energy storage device and a first control valve, one end of the refrigerant branch 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 refrigerant branch circuit;

[0033] The reversing assembly and the first control valve are both connected to the control device, which includes: a memory, a processor, and a control program for the heat pump system stored in the memory and executable on the processor, wherein the control program for the heat pump system implements the steps of the control method for the heat pump system as described in any one of the above items when executed by the processor.

[0034] In addition, in order to achieve the above-mentioned purpose, the present application also proposes a storage medium, on which a control program of a heat pump system is stored. When the control program of the heat pump system is executed by a processor, the steps of the control method of the heat pump system as described in any of the above items are implemented.

[0035] The present invention proposes a control method for a heat pump system. In addition to a refrigerant main circuit including a compressor, an indoor unit, an outdoor heat exchanger and a reversing component, the heat pump system is also provided with a refrigerant branch circuit including an energy storage device and a first control valve. During the operation of the heat pump system in an oil return mode, the outdoor heat exchanger is switched to a high-pressure state and the indoor unit is switched to a low-pressure state through the reversing component. During this process, the opening of the first control valve is controlled according to the supercooling degree of the energy storage device, so that the refrigerant branch circuit can produce 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 indoor unit on the low-pressure side and then flow back to the compressor, thereby 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. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 A schematic diagram of the refrigerant pipeline structure and a schematic diagram of the refrigerant flow direction in the first mode in an embodiment of the heat pump system of the present invention;

[0037] Figure 2 A schematic diagram of the refrigerant pipeline structure in an 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 A schematic diagram of the refrigerant pipeline structure in an 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 A schematic diagram of the refrigerant pipeline structure in an embodiment of a heat pump system of the present invention and a schematic diagram of the refrigerant flow direction in a fourth mode;

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

[0041] Figure 6 A schematic flow chart of an embodiment of a control method for a heat pump system of the present invention;

[0042] Figure 7 A schematic flow chart of another embodiment of a control method for a heat pump system of the present invention;

[0043] Figure 8 A schematic flow chart of another embodiment of a control method for a heat pump system of the present invention;

[0044] Fig. 9 This is a flow chart of another embodiment of a control method for a heat pump system of the present invention.

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

[0046] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0047] An embodiment of the present invention provides a heat pump system.

[0048] In the embodiment of the present invention, refer to Figures 1 to 5 The heat pump system includes a control device 100, a refrigerant main circuit and a refrigerant branch circuit. The refrigerant main circuit includes a compressor 1, an indoor unit, an outdoor heat exchanger 3, a throttling device 4 and a reversing component 5. The refrigerant branch circuit includes 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 component 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, the number of the indoor unit is one. In other embodiments, the number of the indoor unit may be more than one, and more than one indoor unit may 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 . The control device 100 can be used to control the flow rate of refrigerant passing through the indoor heat exchanger 21 .

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

[0056] Through the regulation of the first reversing valve 51, the second reversing valve 52, the first control valve 8 and the second control valve 22, the operation 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 at the first valve position, the second reversing valve 52 operates at the fourth valve position, the second control valve 22 is closed, and the first control valve 8 is opened. All the refrigerant discharged from the compressor 1 flows into the refrigerant branch. The heat of the refrigerant flowing into the refrigerant branch is stored in the energy storage device 7 when flowing 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 and then flows back to the compressor 1. In the first mode, the indoor heat exchanger 21 stops heat exchange, the outdoor heat exchanger 3 is in an evaporating state, and all heat is used to store heat in the energy storage device 7. In the first mode, the energy storage device 7 can store heat separately.

[0058] In the second mode, refer to Figure 2, the first reversing valve 51 operates at the first valve position, the second reversing valve 52 operates at the third valve position, the first control valve 8 is opened, and the second control valve 22 is opened. A part of the refrigerant discharged by the compressor 1 flows through the outdoor heat exchanger 3 and the throttling device 4 in sequence, and another part of the refrigerant discharged by the compressor 1 flows into the refrigerant branch. The heat of the refrigerant flowing into the refrigerant branch is stored in the energy storage device 7 when flowing 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 then flows into the indoor unit for evaporation and then flows back 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 demand, 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; in the second mode, when the indoor space regulated by the indoor unit does not have a heat exchange demand, 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 indoor environment can be cooled while the energy storage device 7 stores heat, or the compressor 1 oil 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 at the first valve position, the second reversing valve 52 operates at the fourth valve position, the first control valve 8 is opened, and the second control valve 22 operates in throttling. All the refrigerant discharged from the compressor 1 flows into the refrigerant branch. The heat of the refrigerant flowing into the refrigerant branch is stored in the energy storage device 7 when flowing through the energy storage device 7. A part of the refrigerant flowing out of the refrigerant branch flows through the throttling device 4 and the outdoor heat exchanger 3 in sequence and then flows back to the compressor 1. The other part of the refrigerant flowing out of the refrigerant branch flows through the second control valve 22 and the indoor heat exchanger 21 in sequence and then flows back to the compressor 1. In the third mode, the indoor heat exchanger 21 and the outdoor heat exchanger 3 are both in an evaporating state. In the third mode, when the indoor space regulated by the indoor unit has a heat exchange demand, 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; in the third mode, when the indoor space regulated by the indoor unit does not have a heat exchange demand, the indoor fan in the indoor unit can be turned off. In the third mode, the heat absorbed by the indoor heat exchanger 21 and the outdoor heat exchanger 3 from the environment in which they are located 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 4, the first reversing valve 51 operates at the first valve position, the second reversing valve 52 operates at the third valve position, the first control valve 8 is closed, and the second control valve 22 is opened. The refrigerant discharged from the compressor 1 flows through the outdoor heat exchanger 3, the throttling device 4, the second control valve 22, and the indoor heat exchanger 21 in sequence and then flows back to the compressor 1. In the fourth 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 demand, 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; in the fourth mode, when the indoor space regulated by the indoor unit does not have a heat exchange demand, 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, and the exhaust port of the compressor 1, the return air port of the compressor 1, the indoor heat exchanger 21 and the outdoor heat exchanger 3 are respectively connected to different valve ports of the third four-way valve.

[0062] Further, see Figures 1 to 5 The heat pump system further includes a pressure sensor 01 , which can be disposed 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] Further, see Figure 5 The heat pump system further includes a temperature detection module 02, which is connected to the control device 100. The temperature detection module 02 includes a first temperature sensor, which is disposed 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, which are respectively disposed at both ends of the indoor heat exchanger 21 to detect the inlet temperature of the indoor heat exchanger 21 and the outlet temperature of the indoor heat exchanger 21.

[0064] In the embodiment of the present invention, refer 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. Among them, these components are connected and communicated through a communication bus. The memory 1002 can be a high-speed RAM memory or a stable memory (non-volatile memory), such as a disk memory. 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 in the figure does not constitute a limitation of the device, and may include more or less components than shown in the figure, or combine certain components, or arrange the components differently.

[0066] like Figure 5 As shown, the memory 1002 as a computer storage medium may include a control program for the 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 step operations of the control method of the heat pump system in the following embodiment.

[0068] An embodiment of the present invention further provides a control method for a heat pump system, which is applied to the above-mentioned heat pump system.

[0069] Reference Figure 6 , an embodiment of a control method of a heat pump system of the present application is proposed. In this embodiment, the control method of the heat pump system includes:

[0070] Step S10, when the heat pump system is in the oil return mode, controlling the first control valve to open and controlling the reversing assembly to operate so that the outdoor heat exchanger is connected to the exhaust port of the compressor, and the indoor unit is connected to the return port of the compressor;

[0071] The oil return mode can be started when it is detected that the heat pump system has reached the oil return condition, or it can be started when a preset instruction input manually is received.

[0072] When the outdoor heat exchanger is connected to the exhaust port of the compressor, the outdoor heat exchanger is in a high-pressure state, and when the indoor unit is connected to the return air port of the compressor, the indoor unit is in a low-pressure state.

[0073] The first control valve may be opened at a preset initial opening (eg, a maximum opening, etc.), or may be opened at an initial opening determined according to actual operation of the heat pump system.

[0074] In the 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 be opened, and the second control valve is controlled to be opened. A part of the refrigerant discharged by the compressor flows through the outdoor heat exchanger and the throttling device in sequence, and another part of the refrigerant discharged by the compressor flows into the refrigerant branch. The heat of the refrigerant flowing into the refrigerant branch is stored in the energy storage device when flowing through 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 for evaporation and then flows back to the compressor. In the 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, obtaining the supercooling degree of the energy storage device;

[0076] The degree of subcooling can accurately reflect the condensation effect during the heat storage process of the energy storage device.

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

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

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

[0080] In one implementation, an opening adjustment parameter may be determined according to the supercooling, and the first control valve may be controlled to adjust the opening according to the opening adjustment parameter. In another implementation, a target opening of the first control valve may be determined according to the supercooling, and the first control valve may 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 of compressor oil mixed with the gaseous refrigerant. Based on this, when the opening of the first control valve is adapted to the supercooling degree for control, 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, thereby avoiding the accumulation of compressor oil in the refrigerant branch.

[0082] A control method for a heat pump system is proposed in an embodiment of the present invention. In addition to the main refrigerant circuit including a compressor, an indoor unit, an outdoor heat exchanger and a reversing assembly, the heat pump system is also provided with a refrigerant branch circuit including 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 1, so that the energy storage device is always connected to the high-speed gaseous refrigerant and the energy storage device is in a state of high pressure. During the oil return mode of the heat pump system, the outdoor heat exchanger is switched to a high-pressure state and the indoor unit is switched to a low-pressure state through the reversing assembly. In this process, the opening of the first control valve is controlled according to the supercooling degree of the energy storage device, so that the refrigerant branch circuit (energy storage device) can produce 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 indoor unit on the low-pressure side and then flow back to the compressor, thereby improving the oil return effect of the pipeline where the energy storage device is located and avoiding oil shortage and damage to the compressor.

[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 degree of supercooling according to the temperature difference between the condensation temperature and the refrigerant temperature.

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

[0085] In this embodiment, the condensing temperature can be calculated by the pressure detected by the pressure sensor. In other embodiments, the condensing temperature can also be detected by a temperature sensor provided at the exhaust side of the compressor.

[0086] In this embodiment, the temperature difference value is determined as the supercooling degree. In other embodiments, it can also be determined according to the actual state parameters of the heat pump system.

[0087] In this embodiment, determining the degree of subcooling in the above manner is beneficial to improving the accuracy of the subcooling in representing the actual amount of liquid refrigerant in the refrigerant branch, ensuring that after the opening of the first control valve is adjusted to adapt to the degree of subcooling, the refrigerant branch has sufficient refrigerant 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] Further, based on the above embodiment, another embodiment of the control method of the heat pump system of the present application is proposed. In this embodiment, referring to Figure 7 , the step S30 comprises:

[0089] Step S31, when the supercooling degree is less than a preset supercooling degree, controlling the first control valve to reduce the opening degree.

[0090] The preset subcooling degree is the maximum subcooling degree of the energy storage device allowed when the system is set to operate reliably and the oil return effect is better.

[0091] The first control valve may be reduced in the process of reducing its opening according to a preset fixed opening adjustment value, or may be reduced according to an opening adjustment value determined by the actual operating state of the heat pump system.

[0092] Step S32: when the degree of supercooling is greater than the preset degree of supercooling, controlling the first control valve to increase its opening.

[0093] The first control valve may increase its opening degree according to a preset fixed opening degree adjustment value during the process of increasing its opening degree, or may increase its opening degree adjustment value determined by the actual operating state of the heat pump system.

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

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

[0096] The first difference is a calculation result obtained by subtracting the supercooling degree from the preset supercooling degree. 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 may be a pre-set fixed relationship, and the correspondence may 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, or the interval in which the first difference is located can be determined, and the opening adjustment value having 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 a subcooling difference and an opening adjustment value is obtained according to the current superheat of the indoor heat exchanger, and the first opening adjustment value corresponding to the first difference is determined according to the first target correspondence. Different superheats may correspond to different first target correspondences, wherein a numerical interval in which the superheat is located may be determined, and a preset correspondence between the difference associated with the numerical interval and the opening adjustment value is used as the first target correspondence. The first target correspondence may include a calculation formula, a mapping relationship, and the like. Based on the first target relationship, the first opening adjustment value may be obtained by calculation, table lookup, and the like.

[0099] In this embodiment, the above method is conducive to ensuring that the supercooling degree of the refrigerant branch can accurately reach the preset supercooling degree after the opening degree of the first control valve is reduced, thereby further effectively improving the oil return effect. Among them, the first opening adjustment value corresponding to the first difference is determined according to the corresponding first target corresponding relationship of the superheat of the indoor heat exchanger, which is conducive to ensuring that the opening adjustment of the first control valve can match the actual evaporation effect of the indoor heat exchanger, and ensure that the refrigerant mixed with compressor oil flowing out of the refrigerant branch can carry as much compressor oil as possible to flow back to the compressor after evaporation through the indoor heat exchanger, thereby further improving the oil return effect of the compressor oil in the refrigerant branch.

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

[0101] The second difference is a calculation result obtained by subtracting the preset supercooling degree from the supercooling degree. 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 may be a pre-set fixed relationship, and the correspondence may include a calculation formula, a mapping relationship, etc. Based on the correspondence, the second opening adjustment value can be calculated by substituting the second difference into the formula, or the interval in which the second difference is located can be determined, and the opening adjustment value having 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 between the subcooling difference and the opening adjustment value is obtained according to the current superheat of the indoor heat exchanger, and the second opening adjustment value corresponding to the second difference is determined according to the second target correspondence. Different superheats may correspond to different second target correspondences, wherein a numerical interval in which the superheat is located may be determined, and a preset correspondence between the difference associated with the numerical interval and the opening adjustment value is used as the second target correspondence. The second target correspondence may include a calculation formula, a mapping relationship, and the like. Based on the second target relationship, the second opening adjustment value may be obtained by calculation, table lookup, and the like.

[0104] In this embodiment, the above method is conducive to ensuring that the supercooling degree of the refrigerant branch can accurately reach the preset supercooling degree after the opening degree of the first control valve is increased, thereby further effectively improving the oil return effect. Among them, the second opening adjustment value corresponding to the second difference is determined according to the corresponding second target corresponding relationship of the superheat of the indoor heat exchanger, which is conducive to ensuring that the opening adjustment of the first control valve can match the actual evaporation effect of the indoor heat exchanger, and ensure that the refrigerant mixed with compressor oil flowing out of the refrigerant branch can carry as much compressor oil as possible to flow back to the compressor after evaporation through the indoor heat exchanger, thereby further improving the oil return effect of the compressor oil in the refrigerant branch.

[0105] Further, based on any of the above embodiments, another embodiment of the control method of the heat pump system of the present application is proposed. Figure 8 , while or after the step of controlling the opening of the first control valve according to the degree of subcooling is performed, it also includes:

[0106] Step S40, obtaining the superheat degree of the indoor heat exchanger;

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

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

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

[0110] In one implementation, an opening adjustment parameter may be determined according to the superheat, and the second control valve may be controlled to adjust the opening according to the opening adjustment parameter. In another implementation, a target opening of the second control valve may be determined according to the superheat, and the second control valve may be controlled to operate at the target opening.

[0111] In this embodiment, in the process of controlling the opening of the first control valve according to the degree of subcooling, the opening of the second control valve is controlled according to the superheat of the indoor heat exchanger, which is beneficial 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 all flow back 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] Further, in this embodiment, step S50 includes: when the superheat is greater than a first preset superheat, controlling the second control valve to increase the opening; when the superheat is less than or equal to a second preset superheat, controlling the second control valve to reduce the 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, and the first preset superheat and the second preset superheat are used as critical values ​​to form a preset superheat interval, and the preset superheat interval represents the target value interval that the evaporation effect of the indoor heat exchanger can ensure that all the compressor oil flowing through the refrigerant is returned to the compressor and the system is running reliably, and the superheat of the indoor heat exchanger needs to reach. In other embodiments, the second preset superheat is equal to the first preset superheat, and the second preset superheat or the first preset superheat represents the target superheat that the evaporation effect of the indoor heat exchanger can ensure that all the compressor oil flowing through the refrigerant is returned to the compressor and the system is running reliably, and the superheat of the indoor heat exchanger needs to reach.

[0114] The second control valve may be reduced in the process of reducing its opening according to a preset fixed opening adjustment value, or may be reduced according to an opening adjustment value determined by the actual operating state of the heat pump system.

[0115] The second control valve may increase its opening degree according to a preset fixed opening degree adjustment value during the process of increasing its opening degree, or may increase its 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 the opening includes: determining a third opening adjustment value according to a third difference between the superheat and the first preset superheat, and controlling the second control valve to increase the opening according to 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 a second preset superheat, the step of controlling the second control valve to reduce the opening includes: determining a fourth opening adjustment value according to a fourth difference between the second preset superheat and the superheat, and controlling the second control valve to reduce the opening according to 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 not good. At this time, controlling the second control valve to reduce the opening is beneficial to increasing the superheat, thereby improving the evaporation effect of the indoor heat exchanger, ensuring that there is enough liquid refrigerant to bring the compressor oil back to the compressor, thereby 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 bring the compressor oil back to the compressor, but the superheat is too high and the system is prone to reliability problems. At this time, controlling the second control valve to increase the opening is beneficial to reducing the superheat, ensuring the oil return effect while improving the reliability of the compressor operation.

[0119] Further, based on any of the above embodiments, another embodiment of the control method of the heat pump system of the present application is proposed. In this embodiment, referring to Fig. 9 , before step S10, it also includes:

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

[0121] When the first control valve is opened and both the indoor unit and the outdoor heat exchanger are connected to the return air port of the compressor, all the refrigerant discharged from the compressor can flow through the energy storage device to store heat.

[0122] In this embodiment, when the heat pump system starts the separate heat storage mode (that is, 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 be closed, and the first control valve is controlled to be opened, and 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 when it flows through the energy storage device, and the refrigerant flowing out of the refrigerant branch flows through the throttling device and the outdoor heat exchanger in turn and then flows back to the compressor. In the heat storage mode, the indoor heat exchanger stops heat exchange, the outdoor heat exchanger is in an evaporating state, and all heat is used for heat storage in the energy storage device.

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

[0124] Step S02, when the heat pump system runs to meet a preset oil return condition, controlling the heat pump system to start an oil return mode.

[0125] When the first control valve is opened, the reversing assembly is operated to connect the outdoor heat exchanger and the indoor unit to the return air port of the compressor, and the second control valve is closed, the state parameters of the heat pump system (such as the compressor operation frequency, etc.) are monitored, and when the state parameters meet the preset oil return conditions, the heat pump system is controlled to start the oil return mode, and the above step S10 is executed. When the state parameters do not meet the preset oil return conditions, the heat pump system can be controlled to maintain the current state operation.

[0126] In this embodiment, when the heat pump system is in the separate heat storage mode, the refrigerant discharged from all compressors flows into the refrigerant branch. The compressor oil is easily discharged to the refrigerant branch along with the refrigerant and accumulates in the refrigerant branch. The risk of the compressor running out of oil is relatively high. At this time, when it is monitored that the heat pump system meets the oil return conditions, the oil return mode is started, which is beneficial to improve the timeliness of the oil return in the refrigerant branch, thereby further reducing the risk of damage to the compressor due to oil shortage in the separate heat storage mode of the heat pump system.

[0127] In addition, an embodiment of the present invention further proposes a storage medium, on which a control program of a heat pump system is stored. When the control program of the heat pump system is executed by a processor, the relevant steps of any embodiment of the control method of the heat pump system are implemented.

[0128] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or system including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or system. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or system including the element.

[0129] The serial numbers of the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0130] Through the description of the above implementation methods, those skilled in the art can clearly understand that the above-mentioned embodiment methods can be implemented by means of software plus a necessary general hardware platform, and of course by hardware, but in many cases the former is a better implementation method. Based on such an understanding, the technical solution of the present invention is essentially or the part that contributes to the prior art can be embodied in the form of a software product, and the computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) as described above, including a number of instructions for a terminal device (which can be a mobile phone, computer, server, heat pump system, or network device, etc.) to execute the methods described in each embodiment of the present invention.

[0131] The above are only preferred embodiments of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A control method for a heat pump system, characterized in that: The heat pump system comprises a refrigerant main circuit and a refrigerant branch circuit, wherein the refrigerant main circuit comprises a compressor, an indoor unit, an outdoor heat exchanger and a reversing assembly, wherein the refrigerant branch circuit comprises an energy storage device and a first control valve, wherein one end of the refrigerant branch circuit is connected to an exhaust port of the compressor, and a pipeline between the indoor unit and the outdoor heat exchanger is connected to the other end of the refrigerant branch circuit, and the control method of the heat pump system comprises the following steps: When the heat pump system is in the oil return mode, the first control valve is controlled to open and the reversing assembly is controlled to operate so that the outdoor heat exchanger is connected to the exhaust port of the compressor, and the indoor unit is connected to the return port of the compressor; Obtaining a degree of supercooling of the energy storage device; The opening degree of the first control valve is controlled according to the subcooling degree so that the compressor oil in the refrigerant branch circuit flows back to the compressor.

2. The control method of the heat pump system according to claim 1, characterized in that: The step of controlling the opening of the first control valve according to the degree of subcooling so that the compressor oil in the refrigerant branch circuit flows back to the compressor comprises: When the degree of subcooling is less than a preset degree of subcooling, controlling the first control valve to reduce its opening degree; When the degree of supercooling is greater than the preset degree of supercooling, the first control valve is controlled to increase its opening degree.

3. The control method of the heat pump system according to claim 2, characterized in that: When the degree of subcooling is less than a preset degree of subcooling, the step of controlling the first control valve to reduce the opening degree comprises: Determining a first opening adjustment value according to a first difference between the preset subcooling degree and the subcooling degree, and controlling the first control valve to reduce the opening according to the first opening adjustment value; When the degree of subcooling is greater than the preset degree of subcooling, the step of controlling the first control valve to increase its opening degree comprises: A second opening adjustment value is determined according to a second difference between the subcooling degree and the preset subcooling degree, and the first control valve is controlled to increase its opening according to the second opening adjustment value.

4. The control method of the heat pump system according to claim 3, characterized in that: The indoor unit includes an indoor heat exchanger, and the step of determining a first opening adjustment value according to a first difference between the preset supercooling degree and the supercooling degree includes: Acquire a first target correspondence between a subcooling degree difference and an opening adjustment value according to the current superheat of the indoor heat exchanger, and determine the first opening adjustment value corresponding to the first difference according to the first target correspondence; And / or, the step of determining the second opening adjustment value according to a second difference between the supercooling degree and the preset supercooling degree includes: A second target correspondence between a subcooling degree difference and an opening adjustment value is obtained according to the current superheat of the indoor heat exchanger, and the second opening adjustment value corresponding to the second difference is determined according to the second target correspondence.

5. The control method of the heat pump system according to claim 1, characterized in that: The indoor unit includes an indoor heat exchanger and a second control valve. While or after the step of controlling the opening of the first control valve according to the supercooling degree is performed, the step further includes: Obtaining a superheat degree of the indoor heat exchanger; The opening degree of the second control valve is controlled according to the superheat degree.

6. The control method of the heat pump system according to claim 5, characterized in that: The step of controlling the opening of the second control valve according to the superheat comprises: When the superheat is greater than a first preset superheat, controlling the second control valve to increase its opening; When the superheat is less than or equal to a second preset superheat, controlling the second control valve to reduce the opening degree; Wherein, the second preset superheat degree is less than or equal to the first preset superheat degree.

7. The control method of the heat pump system according to claim 1, characterized in that: The step of obtaining the supercooling degree of the energy storage device comprises: Obtaining the refrigerant temperature flowing out of the energy storage device and the condensing temperature of the heat pump system; The degree of subcooling is determined according to a temperature difference between the condensing temperature and the refrigerant temperature.

8. The control method of a heat pump system according to any one of claims 1 to 7, characterized in that: 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 exhaust port of the compressor and the indoor unit is connected to the return air port of the compressor when the heat pump system is in the oil return mode, the step further includes: Controlling the first control valve to open, controlling the reversing assembly to operate so that the outdoor heat exchanger and the indoor unit are both connected to the return air port of the compressor, and controlling the second control valve to close; When the heat pump system runs to meet a preset oil return condition, the heat pump system is controlled to start an oil return mode.

9. A heat pump system, characterized in that: The heat pump system includes a control device, a refrigerant main circuit and a refrigerant branch circuit, wherein the refrigerant main circuit includes a compressor, an indoor unit, an outdoor heat exchanger and a reversing assembly, and the refrigerant branch circuit includes an energy storage device and a first control valve, one end of the refrigerant branch 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 refrigerant branch circuit; The reversing assembly and the first control valve are both connected to the control device, which includes: a memory, a processor, and a control program for the heat pump system stored in the memory and executable on the processor, wherein the control program for the heat pump system implements the steps of the control method for the heat pump system as described in any one of claims 1 to 8 when executed by the processor.

10. A storage medium, characterized in that: The storage medium stores a control program of the heat pump system, and when the control program of the heat pump system is executed by the processor, the steps of the control method of the heat pump system according to any one of claims 1 to 8 are implemented.

Images