Heat pump system and control method thereof

Abstract

The application relates to a heat pump system and a control method thereof, which is provided with a liquid injection enthalpy increasing branch, can branch the refrigerant in a refrigerant circulation loop between a first throttling element and an economizer main path, flow into a gas supplement inlet of a compressor through an auxiliary path of the economizer for gas supplement and enthalpy increase. A gas supplement throttling element is arranged on the liquid injection enthalpy increasing branch, an exhaust gas superheat degree is obtained according to an exhaust gas temperature and an exhaust gas pressure, an optional adjustment mode of the opening degree of the gas supplement throttling element is determined according to the exhaust gas superheat degree, an economizer superheat degree is obtained according to an auxiliary path inlet temperature and an auxiliary path outlet temperature, a target adjustment mode is determined from the optional adjustment mode based on the economizer superheat degree, and the opening degree control of the gas supplement throttling element is carried out in the target adjustment mode. The reliability of the compressor can be ensured while the exhaust gas temperature is reduced and the refrigerating and heating capacity is improved. The heat exchange capacity of the economizer can be fully utilized, the refrigerant can be sufficiently supercooled to improve the evaporation capacity of the evaporator.

Description

Technical Field

[0001] This application relates to the field of heat pump technology, and in particular to a heat pump system and its control method. Background Technology

[0002] With the advancement of technology, there are increasingly more technologies for heating and cooling indoor environments. Among them, heat pump technology can efficiently utilize low-temperature heat energy and is used in various fields such as domestic hot and cold water, air conditioning, and heating. It has been widely applied in the current situation of tight energy supply and increasingly stringent environmental protection requirements.

[0003] In traditional technologies, adding gas to the compressor of a heat pump system to increase its enthalpy and improve its cooling and heating capacity is a product of the expansion of heat pump technology into the low-temperature field. This effectively reduces the compressor's exhaust temperature, enabling the system to operate reliably for a long time. However, in this process, the problem of liquid carryover during suction still exists, posing a safety hazard to the operation of the heat pump system. Summary of the Invention

[0004] This application provides a heat pump system and its control method to solve the technical problem of liquid carryover during the process of replenishing gas and increasing enthalpy of the compressor.

[0005] In a first aspect, some embodiments provide a heat pump system, including:

[0006] The refrigerant circulation loop allows the refrigerant to circulate in a loop consisting of a compressor, a four-way valve, an outdoor heat exchanger, a first throttling element, an economizer, and an indoor heat exchanger.

[0007] The liquid injection enthalpy-increasing branch allows the refrigerant diverted from the refrigerant circulation loop to flow from the first throttling element and the main circuit of the economizer, through the auxiliary circuit of the economizer, into the compressor's gas inlet. The liquid injection enthalpy-increasing branch is also equipped with a gas inlet throttling element.

[0008] A temperature sensing component is used to acquire the discharge temperature of the compressor, the auxiliary inlet temperature of the economizer, and the auxiliary outlet temperature.

[0009] A pressure sensing element is used to obtain the discharge pressure of the compressor;

[0010] The controller is configured as follows:

[0011] The exhaust superheat is obtained based on the exhaust temperature and the exhaust pressure, and an optional adjustment method for the opening of the air-injection throttling element is determined based on the exhaust superheat. The adjustment method includes at least increasing, decreasing, and maintaining. The economizer superheat is obtained based on the auxiliary road inlet temperature and the auxiliary road outlet temperature. A target adjustment method is determined from the optional adjustment methods based on the economizer superheat, and the opening of the air-injection throttling element is controlled using the target adjustment method.

[0012] The heat pump system comprises a refrigerant circulation loop, and the refrigerant circulates in the loop composed of a compressor, a four-way valve, an outdoor heat exchanger, a first throttling element, an economizer and an indoor heat exchanger. The system further comprises a liquid injection enthalpy increasing branch, which can divert the refrigerant in the refrigerant circulation loop between the first throttling element and the main path of the economizer, and the refrigerant in the auxiliary path of the economizer flows into the charge port of the compressor to increase the enthalpy. Further, the liquid injection enthalpy increasing branch is provided with a charge throttling element, and the controller can be connected with a temperature sensing assembly and a pressure sensing element to obtain the discharge temperature and discharge pressure of the compressor, and the inlet temperature and outlet temperature of the auxiliary path of the economizer. Further, the controller obtains the discharge superheat degree according to the discharge temperature and discharge pressure, and determines the optional adjustment mode of the opening degree of the charge throttling element according to the discharge superheat degree, and the adjustment mode at least includes increasing, decreasing and keeping; the economizer superheat degree is obtained according to the inlet temperature and outlet temperature of the auxiliary path, and the target adjustment mode is determined from the optional adjustment mode based on the economizer superheat degree, and the opening degree of the charge throttling element is controlled in the target adjustment mode.

[0013] The optional adjustment mode of the opening degree of the charge throttling element is limited according to the discharge superheat degree, and the target adjustment mode is determined from the optional adjustment mode in combination with the economizer superheat degree, which can reduce the discharge temperature and improve the refrigeration and heating capacity while ensuring the reliability of the compressor. For example, in the case of high discharge superheat degree, which represents high discharge temperature and increased load of the compressor, the optional adjustment mode of the charge throttling element can be limited to increasing, so that more refrigerant circulation amount is obtained by the liquid injection enthalpy increasing branch, the heat exchange performance of the economizer is fully utilized, and the discharge temperature of the compressor is reduced to ensure that the discharge superheat degree of the compressor returns to the normal level. For the case of excessively low discharge superheat degree, which represents excessively low discharge temperature and insufficient refrigerant circulation amount in the refrigerant circulation loop, the liquid return phenomenon may occur, and the optional adjustment mode of the charge throttling element can be limited to decreasing, so as to reduce the refrigerant circulation amount obtained by the liquid injection enthalpy increasing branch, and ensure that there is sufficient refrigerant circulation amount in the refrigerant circulation loop to maintain stable operation of the compressor. On the basis of the above, the economizer superheat degree is used as a reference basis for selecting the target opening degree mode of the charge throttling element, which can ensure that the heat exchange capacity of the economizer is fully utilized, and the refrigerant can obtain sufficient supercooling degree after passing through the main path of the economizer to improve the heat absorption capacity of the evaporator. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related art, the drawings needed in the description of the embodiments of the present application or the related art will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other related drawings can be obtained by those skilled in the art without creating any inventive labor.

[0015] Figure 1 A schematic diagram of refrigerant flow paths in a heat pump system in a heating mode according to one embodiment;

[0016] Figure 2 A schematic diagram of refrigerant flow paths in a heat pump system in a cooling mode according to one embodiment;

[0017] Figure 3 A schematic diagram of a heat pump system according to one embodiment;

[0018] Figure 4 A schematic diagram of a heat pump system according to another embodiment;

[0019] Figure 5 A schematic diagram of a heat pump system according to yet another embodiment;

[0020] Figure 6 A schematic diagram of a heat pump system according to still another embodiment;

[0021] Figure 7 A schematic diagram of a heat pump system according to yet another embodiment;

[0022] Figure 8 A schematic diagram of a control method for a heat pump system according to one embodiment;

[0023] Figure 9 A schematic diagram of a control method for a heat pump system according to another embodiment;

[0024] Figure 10 A schematic diagram of a control method for a heat pump system according to yet another embodiment;

[0025] Figure 11 A schematic diagram of a control method for a heat pump system according to still another embodiment;

[0026] Figure 12 A schematic diagram of a control method for a heat pump system according to yet another embodiment. DETAILED DESCRIPTION

[0027] Embodiments will be described in detail below with reference to the attached drawings. The description below refers to the accompanying drawings, which show embodiments by way of example. The description below is not intended to be limited to the embodiments described below. Rather, the description below is intended to be illustrative of systems and methods consistent with the present application, which are set out in the claims below.

[0028] It is to be understood that the phrases "first," "second," "third," and the like in the present application do not necessarily imply a specific order or sequence, unless otherwise specified. It is to be understood that such terms are used herein, for illustrative purposes only and can be interchanged with each other, as appropriate, to describe various embodiments of the present application.

[0029] The terms "first," "second," "third," and the like in the present application do not necessarily imply a specific order or sequence, unless otherwise specified. It is to be understood that such terms are used herein, for illustrative purposes only and can be interchanged with each other, as appropriate, to describe various embodiments of the present application.

[0030] The terms "include," "includes," and "including" are intended to be inclusive and mean for example that a product or device that is encompassed by the term includes, but is not limited to, all components clearly listed, but also includes other components not clearly listed or inherent to such product or device.

[0031] The term "module" refers to any known or later developed hardware, software, firmware, artificial intelligence, fuzzy logic, or combination of hardware and / or software code that is capable of performing the functions associated with that element.

[0032] Referring to Figure 1 An internal structure diagram of a heat pump system provided in an embodiment of the present application is shown in FIG. 1. The internal components of the heat pump system include a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, a first throttling element 4, an economizer 5, and an indoor heat exchanger 6. The above components can be connected via pipes to form a refrigerant circulation loop for circulating and flowing refrigerant to achieve the refrigeration and heating functions of the heat pump system.

[0033] It can be understood that the heat pump system can switch between the cooling mode and the heating mode by reversing the four-way valve 2. For example, Figure 1As shown, in heating mode, low-temperature, low-pressure gaseous refrigerant is drawn into compressor 1 through the suction port and pressurized into a high-temperature, high-pressure gas. This high-temperature, high-pressure gas then enters indoor heat exchanger 6 (used as a condenser) via four-way valve 2. Here, the refrigerant releases heat through condensation and liquefaction, which is transferred to the indoor air, thus raising the indoor air temperature. The condensed and liquefied liquid refrigerant is then depressurized by the first throttling element 4, reducing its pressure and temperature to prepare for the subsequent evaporation process. At this point, the liquid refrigerant can also be subcooled again by economizer 5 to achieve higher cooling efficiency when it enters the evaporator. The depressurized liquid refrigerant then enters outdoor heat exchanger 3 (used as an evaporator). In the evaporator, the refrigerant absorbs heat from the outdoor air through evaporation and vaporization, becoming a low-temperature, low-pressure gaseous refrigerant, which is then drawn back into compressor 1 to begin the next cycle. This process is repeated, and through continuous liquefaction and vaporization cycles, heat is transferred from the outside to the inside, achieving the purpose of heating.

[0034] like Figure 2 As shown, in cooling mode, low-temperature, low-pressure gaseous refrigerant is drawn into compressor 1 through the suction port and pressurized into a high-temperature, high-pressure gas. This high-temperature, high-pressure gas then enters the outdoor heat exchanger 3 (which functions as a condenser) via the four-way valve 2. In the condenser, heat exchange effectively releases the heat carried by the hot vapor, which is then blown out of the unit through the outdoor unit's air outlet. The condensed, low-temperature, high-pressure liquid refrigerant can then be subcooled again by the economizer 5 to achieve higher cooling efficiency when it enters the evaporator. The subcooled high-pressure liquid refrigerant then passes through the first throttling element 4 to reduce its pressure and temperature, preparing for the subsequent evaporation process. The low-temperature, low-pressure liquid refrigerant then enters the indoor heat exchanger 6 (which functions as an evaporator). In the evaporator, the liquid refrigerant vaporizes, absorbing a large amount of heat. Due to this heat absorption, the air temperature around the evaporator decreases, and the indoor unit's fan then blows this low-temperature air into the room through the air outlet, thereby lowering the indoor air temperature. The refrigerant, after vaporizing in the evaporator, reverts to a low-temperature, low-pressure gaseous state and is drawn back into compressor 1 to begin the next cycle. This process repeats continuously, transferring heat from the indoor to the outdoor environment through the constant cycle of liquefaction and vaporization, thus achieving the purpose of cooling.

[0035] It should be noted that, based on the different heat exchange principles of the outdoor heat exchanger 3 and the indoor heat exchanger 6 when used as condensers, such as air cooling, water cooling or other heat exchange methods, the heat pump system can correspond to different forms of heat pump system, and the embodiments of this application do not limit this.

[0036] In one exemplary embodiment, please continue to refer to Figure 1 and Figure 2, the heat pump system further comprises: a liquid injection enthalpy increasing branch, the refrigerant branched from the refrigerant circulation loop flows into the air supplement port of the compressor 1 through the auxiliary path of the economizer 5 between the first throttling element 4 and the main path of the economizer 5, and the air supplement throttling element 7 is arranged on the liquid injection enthalpy increasing branch.

[0037] The liquid injection enthalpy increasing branch is connected with the air supplement port of the compressor, and the medium pressure cavity of the compressor 1 is supplemented with the refrigerant to increase the circulation amount of the high temperature and high pressure refrigerant output by the compressor 1. Specifically, the economizer 5 comprises a main path (lower path) and an auxiliary path (upper path). The inlet of the main path is connected with the condenser side, and the outlet of the main path is connected with the evaporator side, and is used for supercooling the low temperature refrigerant after heat release in the condenser to a liquid state. The inlet of the auxiliary path is connected with the first throttling element 4 and the economizer 5 through the air supplement throttling element 7, and the outlet of the auxiliary path is connected with the air supplement port of the compressor 1. The air supplement throttling element 7 is used for throttling and cooling the refrigerant branched from the refrigerant circulation loop. The throttled refrigerant enters the auxiliary path of the economizer 5, exchanges heat with the main path, is evaporated into medium pressure superheated steam by absorbing heat, and enters the compressor 1 to increase the enthalpy, so as to improve the refrigeration and heating energy efficiency of the heat pump system.

[0038] Exemplarily, a one-way valve is arranged on the pipeline connecting the outlet of the auxiliary path of the economizer 5 with the air supplement port of the compressor 1. The one-way valve is used for ensuring that the refrigerant can only flow from the auxiliary path of the economizer 5 to the air supplement port of the compressor 1, and effectively avoids the reverse flow of the refrigerant in the pipeline, which causes the economizer 5 to be overheated and damaged.

[0039] In an exemplary embodiment, the heat pump system further comprises a temperature sensing assembly for obtaining the exhaust temperature of the compressor, the inlet temperature and the outlet temperature of the auxiliary path of the economizer, and a pressure sensing element for obtaining the exhaust pressure of the compressor.

[0040] Please continue to refer to Figure 1 and Figure 2 The temperature sensing assembly can comprise a first temperature sensor 8, a second temperature sensor 9 and a third temperature sensor 10. The first temperature sensor 8 can be arranged at any position on the pipeline connecting the compressor 1 with the condenser, for example, the first temperature sensor 8 can be arranged at the exhaust port of the compressor 1 to detect the exhaust temperature of the compressor 1. The second temperature sensor 9 is arranged at the inlet of the auxiliary path of the economizer 5 to detect the inlet temperature of the auxiliary path of the economizer 5. The third temperature sensor 10 is arranged at the outlet of the auxiliary path of the economizer 5 to detect the outlet temperature of the auxiliary path of the economizer 5. The pressure sensing element is a pressure sensor 11, which can be arranged at the exhaust port of the compressor 1 to detect the exhaust pressure of the compressor 1.

[0041] Exemplarily, the specific device selection of the above-mentioned temperature sensor and pressure sensor is not limited, and the person skilled in the art can select according to the actual technical requirements.

[0042] In an exemplary embodiment, the heat pump system further comprises a controller (not shown in the figure). The controller is the master control center of the heat pump system, which can be used to connect various types of sensing elements arranged in the heat pump system to analyze the operating state and control the operating parameters of the core devices such as the compressor 1, the outdoor heat exchanger 3 and the indoor heat exchanger 6. At the same time, the controller can also be used to control the opening and closing state of various pumps and valve elements in the refrigerant circulation loop and branch to ensure more efficient circulation of heat by the refrigerant.

[0043] In an exemplary embodiment, please continue to refer to Figure 1 and Figure 2 The controller is configured to: obtain the exhaust gas superheat degree according to the exhaust gas temperature and the exhaust gas pressure, and determine the optional adjustment mode of the opening degree of the supplementary air throttling element 7 according to the exhaust gas superheat degree, the adjustment mode at least including increasing, decreasing and keeping; obtain the economizer superheat degree according to the auxiliary road inlet temperature and the auxiliary road outlet temperature, determine the target adjustment mode from the optional adjustment mode based on the economizer superheat degree, and control the opening degree of the supplementary air throttling element 7 in the target adjustment mode.

[0044] The exhaust gas superheat degree is used to measure the degree to which the temperature of the refrigerant gas discharged by the compressor 1 is higher than the saturation temperature corresponding to its pressure, which is crucial for ensuring the stable operation of the compressor and the heat pump system. Specifically, the exhaust gas superheat degree can be determined by the exhaust gas temperature of the compressor and the outlet temperature of the condenser, or by the exhaust gas temperature of the compressor and the saturation temperature corresponding to the exhaust gas pressure. In an exemplary embodiment of the present application, the saturation temperature corresponding to the exhaust gas pressure of the compressor 1 is first calculated, and then the difference between the exhaust gas temperature and the saturation temperature corresponding to the exhaust gas pressure is calculated, which is the exhaust gas superheat degree of the compressor 1.

[0045] It can be understood that if the exhaust gas superheat degree is too high, it means that the exhaust gas temperature is too high, which may cause the compressor load to increase and the power consumption to increase, which may cause equipment damage or safety accidents. Therefore, in this case, the supplementary air throttling element 7 can be effectively adjusted to make the liquid injection enthalpy increase branch divert more refrigerant circulation amount, fully exert the heat exchange performance of the economizer 5, and at the same time reduce the compressor exhaust gas temperature to ensure that the compressor exhaust gas superheat degree returns to normal level. Exemplarily, the effective adjustment of the supplementary air throttling element 7 to make the liquid injection enthalpy increase branch divert more refrigerant circulation amount can be to limit the optional adjustment mode of the opening degree of the supplementary air throttling element 7 to increasing.

[0046] The exhaust gas superheat is too low, which indicates that the exhaust gas temperature is lower than the saturation temperature corresponding to the pressure of the exhaust gas, and the refrigerant circulating amount in the refrigerant circulating loop is insufficient, which leads to the exhaust gas temperature being too low and further leads to the liquid return phenomenon, affecting the oil separation effect, and even damaging the compressor. Correspondingly, in this case, the gas supplement throttling element 7 can be effectively adjusted to reduce the refrigerant circulating amount obtained by the liquid injection enthalpy increase branch shunt, so as to ensure that there is sufficient refrigerant circulating amount in the refrigerant circulating loop to maintain stable operation of the compressor. For example, the effective adjustment of the gas supplement throttling element 7 to reduce the refrigerant circulating amount obtained by the liquid injection enthalpy increase branch shunt can be to limit the optional adjustment mode of the opening degree of the gas supplement throttling element 7 to be adjusted smaller.

[0047] Of course, in the case where the exhaust gas superheat is within the normal range, the optional adjustment mode of the opening degree of the gas supplement throttling element 7 can be any mode without limitation, for example, the adjustment mode can be adjusted larger, or adjusted smaller, or kept unchanged.

[0048] After determining the optional adjustment mode of the opening degree of the gas supplement throttling element 7 based on the exhaust gas superheat, the target adjustment mode is determined from the determined optional adjustment mode based on the economizer superheat, so as to adjust the opening degree of the gas supplement throttling element 7 according to the selected target adjustment mode.

[0049] The economizer superheat is the difference between the inlet temperature of the auxiliary path and the outlet temperature of the auxiliary path. Taking the economizer superheat as the reference basis for controlling the opening degree of the gas supplement throttling element 7 can ensure that the heat exchange capacity of the economizer is fully utilized, and after passing through the main path of the economizer, the refrigerant can obtain sufficient supercooling degree to improve the evaporator heat absorption capacity.

[0050] The above heat pump system limits the optional adjustment mode of the opening degree of the gas supplement throttling element according to the exhaust gas superheat, and determines the target adjustment mode from the optional adjustment mode in combination with the economizer superheat, which can reduce the exhaust gas temperature and improve the refrigeration and heating capacity while ensuring the reliability of the compressor.

[0051] In an exemplary embodiment, the controller is further configured to: if the exhaust gas superheat is greater than a first exhaust gas superheat threshold, determine that the optional adjustment mode of the opening degree of the gas supplement throttling element includes increasing and keeping; if the exhaust gas superheat is less than a second exhaust gas superheat threshold, determine that the optional adjustment mode of the opening degree of the gas supplement throttling element includes decreasing and keeping; if the exhaust gas superheat is between the second exhaust gas superheat threshold and the first exhaust gas superheat threshold, determine that the optional adjustment mode of the opening degree of the gas supplement throttling element includes increasing, decreasing and keeping; wherein the first exhaust gas superheat threshold is greater than the second exhaust gas superheat threshold.

[0052] Specifically, the first exhaust gas superheat threshold is an upper threshold of the compressor exhaust gas superheat, and exceeding the threshold represents that the exhaust gas superheat is high. The second exhaust gas superheat threshold is a lower threshold of the compressor exhaust gas superheat, and being lower than the threshold represents that the exhaust gas superheat is too low. The specific values of the first exhaust gas superheat threshold and the second exhaust gas superheat threshold are not limited, and can be determined comprehensively according to the type, working environment and load condition of the compressor. For example, in the embodiment of the present application, the first exhaust gas superheat threshold can be set to 40°C, and the second exhaust gas superheat threshold can be set to 35°C.

[0053] Further, if the exhaust gas superheat is greater than the first exhaust gas superheat threshold, it represents that the exhaust gas temperature exceeds the saturation temperature corresponding to its pressure to a high degree, that is, the exhaust gas temperature is high, which can cause the compressor load to increase and the power consumption to increase, and can cause equipment damage or safety accidents. Further, the optional adjustment mode of the opening of the supplementary gas throttling element can include increasing and keeping, so that the liquid injection enthalpy increasing branch obtains more refrigerant circulation amount, fully plays the heat exchange performance of the economizer, and at the same time reduces the compressor exhaust gas temperature to ensure that the compressor exhaust gas superheat returns to the normal level.

[0054] If the exhaust gas superheat is less than the second exhaust gas superheat threshold, it represents that the exhaust gas temperature exceeds the saturation temperature corresponding to its pressure to a low degree, which represents that the refrigerant circulation amount in the refrigerant circulation loop is insufficient, causing the exhaust gas temperature to be too low, which can further cause the liquid return phenomenon, affect the oil separation effect, and even damage the compressor. Further, the optional adjustment mode of the opening of the supplementary gas throttling element can include decreasing and keeping, so as to reduce the refrigerant circulation amount obtained by the liquid injection enthalpy increasing branch, and ensure that there is enough refrigerant circulation amount in the refrigerant circulation loop to maintain stable operation of the compressor.

[0055] If the exhaust gas superheat is between the second exhaust gas superheat threshold and the first exhaust gas superheat threshold, it belongs to the normal range, and the optional adjustment mode of the opening of the supplementary gas throttling element can be any mode, which does not need to be limited, that is, it can include increasing, decreasing and keeping.

[0056] In an exemplary embodiment, the controller is further configured to: determine the current adjustment mode based on the comparison result of the economizer superheat and the target economizer superheat; if the current adjustment mode belongs to the optional adjustment mode, determine that the current adjustment mode is the target adjustment mode; otherwise, determine that the target adjustment mode is keeping.

[0057] Specifically, the target economizer superheat is a target value at which the desired economizer superheat is maintained, and can be set based on considerations such as the efficiency, stability, and avoidance of the risk of compressor liquid knock of the heat pump system. In this embodiment, based on the comparison result of the economizer superheat and the target economizer superheat, the current adjustment mode can be determined, that is, it is determined whether the opening adjustment of the supplementary air throttling element is needed at present and how to adjust the opening of the supplementary air throttling element to achieve the purpose of maintaining the economizer superheat at the target economizer superheat.

[0058] For example, the controller is further configured to: if the economizer superheat meets the target economizer superheat, determine that the current adjustment mode is to maintain; if the economizer superheat exceeds the target economizer superheat, determine that the current adjustment mode is to increase; and if the economizer superheat is lower than the target economizer superheat, determine that the current adjustment mode is to decrease.

[0059] If the economizer superheat exceeds the target economizer superheat, it indicates that the circulating amount of refrigerant obtained by the liquid injection enthalpy increasing branch is insufficient, and therefore, in order to improve the heat exchange performance of the economizer, the current adjustment mode can be determined to be increased. If the economizer superheat is lower than the target economizer superheat, it indicates that the circulating amount of refrigerant obtained by the liquid injection enthalpy increasing branch exceeds the heat exchange demand, and therefore, the current adjustment mode can be determined to be decreased.

[0060] For example, the way to determine whether the economizer superheat meets the target economizer superheat can be to calculate the difference between the economizer superheat and the target economizer superheat to obtain an economizer superheat difference. If the economizer superheat difference is within a preset difference range, it indicates that the economizer superheat meets the target economizer superheat. If the economizer superheat difference is greater than the preset difference range, it indicates that the economizer superheat exceeds the target economizer superheat. If the economizer superheat difference is less than the preset difference range, it indicates that the economizer superheat is lower than the target economizer superheat.

[0061] Further, after determining the current adjustment mode according to the economizer superheat, it needs to be matched with the optional adjustment mode to obtain a target adjustment mode, so as to ensure that the target adjustment mode meets the limitation requirement of the exhaust gas superheat. Specifically, if the current adjustment mode belongs to the optional adjustment mode, it is determined that the current adjustment mode is the target adjustment mode; otherwise, it is determined that the target adjustment mode is to maintain. It can be understood that if the adjustment mode determined according to the economizer superheat does not meet the limitation requirement of the exhaust gas superheat, the opening of the supplementary air throttling element needs to be maintained unchanged to avoid affecting the operation reliability of the compressor. If the adjustment mode determined according to the economizer superheat meets the limitation requirement of the exhaust gas superheat, the opening adjustment of the supplementary air throttling element can be directly performed according to the current adjustment mode.

[0062] It needs to be explained that in the case that the determined target adjustment mode is to increase or decrease, the gas supplement throttling element can be adjusted by a fixed adjustment step until the economizer overheat degree meets the target economizer overheat degree. Among them, if the target adjustment mode is to increase, and the opening degree of the gas supplement throttling element has reached the maximum opening degree threshold, the current opening degree can be maintained; if the target adjustment mode is to decrease, and the opening degree of the gas supplement throttling element has reached the minimum opening degree threshold, the current opening degree can be maintained.

[0063] In addition, after adjusting the gas supplement throttling element, the above-mentioned temperature and pressure parameters can be obtained again after waiting for an adjustment interval time, and the exhaust gas overheat degree and the economizer overheat degree are analyzed to further determine whether the gas supplement throttling element needs to be adjusted. In this embodiment, during the adjustment of the gas supplement throttling element, the adjustment interval time is set, which can avoid frequent fluctuations of the system due to the adjustment of the opening degree of the throttling element, and is beneficial to ensure the operation stability of the heat pump system.

[0064] In one exemplary embodiment, as shown in Figure 3 The liquid injection enthalpy increasing branch is also provided with a gas-liquid separation element 12 and a first electromagnetic valve 13. The refrigerant flowing out of the auxiliary path of the economizer 5 enters the gas-liquid separation element 12, the separated gaseous refrigerant is supplemented into the gas supplement port of the compressor 1, and the separated liquid refrigerant flows into the suction port of the compressor 1 through the first electromagnetic valve 13.

[0065] Specifically, the refrigerant flowing out of the auxiliary path of the economizer 5 can enter from the middle part of the gas-liquid separation element 12. Under the action of gravity, the gaseous refrigerant will be output from the upper part of the gas-liquid separation element 12, supplemented into the gas supplement port of the compressor 1 through the one-way valve, realizing the gas supplement and enthalpy increase of the compressor 1. While the liquid refrigerant will flow out from the lower part of the gas-liquid separation element 12, flow into the suction port of the compressor 1 through the first electromagnetic valve 13, avoiding the risk of liquid compression, and also realizing the liquid injection cooling of the compressor. Exemplarily, a throttling element such as a capillary tube can also be arranged on the pipeline through which the liquid refrigerant flows into the suction port of the compressor 1 through the first electromagnetic valve 13, to throttle and cool the refrigerant exchanged out of the auxiliary path of the economizer 5.

[0066] In one exemplary embodiment, the controller is also configured to: if the exhaust gas overheat degree is between the second exhaust gas overheat degree threshold and the first exhaust gas overheat degree threshold, and the economizer overheat degree is lower than the target economizer overheat degree, open the first electromagnetic valve.

[0067] Specifically, when the exhaust gas superheat degree is between the second exhaust gas superheat degree threshold value and the first exhaust gas superheat degree threshold value, it indicates that the exhaust gas superheat degree is in the normal exhaust gas superheat degree range, and the economizer superheat degree is lower than the target economizer superheat degree, which indicates that the refrigerant circulation amount obtained by the liquid injection enthalpy increasing branch splitting is excessive. In order to avoid the risk of liquid compression caused by liquid from the liquid injection enthalpy increasing branch returning to the compression chamber of the compressor, the first electromagnetic valve 13 needs to be opened to return the separated liquid refrigerant to the suction port of the compressor 1.

[0068] In an exemplary embodiment, the controller is further configured to: record a first time when the operating frequency of the compressor is greater than a preset operating frequency; and open the air supplement throttling element and adjust the opening degree of the air supplement throttling element to a minimum opening degree threshold value when the first time exceeds a preset time length.

[0069] Specifically, the controller can determine whether to open the air supplement throttling element to supplement and increase the enthalpy of the compressor through the liquid injection enthalpy increasing branch according to the operating state of the compressor. The operating state of the compressor can be described by the operating frequency of the compressor, or can be described by the combination of the exhaust pressure and the suction pressure of the compressor.

[0070] For example, the present embodiment can set the preset operating frequency as the opening condition of the air supplement throttling element. Specifically, the operating frequency of the compressor can be obtained in real time, and when it is detected that the operating frequency of the compressor is greater than the preset operating frequency, it indicates that the heating and cooling energy efficiency of the compressor at this time is low and cannot meet the current heating or cooling demand. Then, the first time can be recorded to determine whether the condition that the operating frequency of the compressor is greater than the preset operating frequency reaches a preset time length. When the first time exceeds the preset time length, the air supplement throttling element is opened to supplement and increase the enthalpy of the compressor through the refrigerant obtained by the liquid injection enthalpy increasing branch splitting, thereby improving the heating and cooling capacity of the heat pump system. The specific values of the preset operating frequency and the preset time length can be selected according to actual technical requirements. For example, in the present embodiment, the preset operating frequency is set to 35 Hz, and the preset time length is set to 10 minutes.

[0071] In an exemplary embodiment, as shown in Figure 4 The heat pump system further includes a liquid bypass branch through which the refrigerant split from the refrigerant circulation loop flows into the suction port of the compressor 1 between the indoor heat exchanger 6 and the main path of the economizer 5, and a second electromagnetic valve 14 is arranged on the liquid bypass branch. The controller is further configured to open the second electromagnetic valve 14 when the exhaust gas temperature is greater than an exhaust gas temperature threshold value.

[0072] Specifically, the liquid bypass branch is only opened when the compressor discharge temperature is too high. The discharge temperature threshold is the temperature value at which the discharge temperature is too high. When the discharge temperature is greater than the discharge temperature threshold, the controller can open the second electromagnetic valve 14 to make the liquid refrigerant directly return to the suction port of the compressor 1 through the liquid bypass branch, cool the compressor, quickly reduce the discharge temperature, and ensure stable operation of the heat pump system.

[0073] The specific value of the discharge temperature threshold can be selected according to actual technical requirements. For example, in the present embodiment, the discharge temperature threshold is set to 100°C.

[0074] When the heat pump system is in a heating mode, the liquid refrigerant condensed and liquefied in the indoor heat exchanger 6 can directly flow back to the suction port of the compressor 1 through the liquid bypass branch, quickly reduce the discharge temperature, and reduce the flashing of the refrigerant during the circulation process from the indoor heat exchanger 6 to the outdoor heat exchanger 3, thereby avoiding the attenuation of the heating capacity of the heat pump system and expanding the use range of the system.

[0075] When the heat pump system is in a cooling mode, the liquid refrigerant subcooled by the economizer 5 can directly flow back to the suction port of the compressor 1 through the liquid bypass branch, quickly reduce the discharge temperature, and reduce the flashing of the refrigerant during the circulation process from the outdoor heat exchanger 3 to the indoor heat exchanger 6, thereby avoiding the attenuation of the cooling capacity of the heat pump system and expanding the use range of the system.

[0076] In an exemplary embodiment, as shown in Figure 5 As shown in Figure 6 The heat pump system further comprises a second throttling element 15 located between the indoor heat exchanger 6 and the main path of the economizer 5. The first throttling element 4 and the second throttling element 15 are both one-way throttling valves.

[0077] The one-way throttling valve is a valve that controls the flow of fluid by changing the throttling section or the throttling length. Fluid can flow freely when flowing through the one-way throttling valve from one direction, but has a throttling effect when flowing from the other direction, i.e., the flow of fluid can be limited. The one-way throttling valve is usually composed of a valve body, a valve core, a spring and other components. When fluid flows from the inlet end, the valve core is moved by the pressure and opens the channel to allow the fluid to flow through. At this time, the one-way throttling valve functions as a one-way valve, allowing fluid to flow in only one direction. When fluid flows from the other direction (i.e., the outlet end), the valve core blocks part of the channel, functioning as a throttling effect. By adjusting the gap between the valve core and the valve seat, the flow of fluid can be controlled.

[0078] Specifically, referring to Figure 5When the heat pump system is in the cooling mode, the refrigerant flows from the outdoor heat exchanger 3 to the main passage of the economizer 5 through the first throttling element 4, at this time the first throttling element 4 is in the open state, and the refrigerant can flow freely through the first throttling element 4. When the refrigerant completes heat exchange in the main passage of the economizer 5, it flows into the indoor heat exchanger 6 through the second throttling element 15, at this time the second throttling element 15 is in the throttling state, and the refrigerant can be throttled and reduced in pressure and temperature by the second throttling element 15.

[0079] With reference to Figure 6 When the heat pump system is in the heating mode, the refrigerant flows from the indoor heat exchanger 6 to the main passage of the economizer 5 through the second throttling element 15, at this time the second throttling element 15 is in the open state, and the refrigerant can flow freely through the second throttling element 15. When the refrigerant completes heat exchange in the main passage of the economizer 5, it flows into the outdoor heat exchanger 3 through the first throttling element 4, at this time the first throttling element 4 is in the throttling state, and the refrigerant can be throttled and reduced in pressure and temperature by the first throttling element 4.

[0080] In the present embodiment, by arranging the one-way throttling valves at both ends of the economizer, it can be ensured that, in either the heating mode or the cooling mode, the refrigerant is not throttled before being subcooled in the economizer, but is throttled after being subcooled in the economizer, so as to improve the subcooling capacity of the economizer and the heating and cooling capacity of the heat pump system.

[0081] Exemplarily, the controller is further configured to control the opening degree of the first throttling element when the operation mode of the heat pump system is the heating mode, and control the opening degree of the second throttling element when the operation mode of the heat pump system is the cooling mode.

[0082] Specifically, the controller can control the opening degree of the first throttling element / second throttling element during the operation of the heat pump system according to the operating state of the compressor, so as to adjust the circulation amount of the refrigerant in the refrigerant circulation loop and ensure stable operation of the system in the cooling and heating modes. The data basis for controlling the opening degree of the first throttling element / second throttling element is not unique, and can be the suction superheat degree of the compressor and the target suction superheat degree, the discharge superheat degree of the compressor and the target discharge superheat degree, the operating parameters of the indoor heat exchanger 3 or the outdoor heat exchanger 6, or any combination of the above operating parameters. The data basis can be selected according to technical requirements, as long as it can adjust the circulation amount of the refrigerant in the refrigerant circulation loop to ensure stable operation of the system in the cooling and heating modes.

[0083] In one exemplary embodiment, as Figure 7As shown, the heat pump system further comprises: a gas bypass branch, the refrigerant branched from the refrigerant circulation loop flows into the suction port of the compressor 1 from the exhaust port of the compressor 1, and a third electromagnetic valve 16 is arranged on the gas bypass branch. The controller is further configured to open the third electromagnetic valve 16 if the exhaust pressure is greater than the exhaust pressure threshold.

[0084] Specifically, the gas bypass branch is only opened in the case that the exhaust pressure of the compressor is too high. The exhaust pressure threshold is the pressure value at which the exhaust pressure is too high. When the exhaust pressure is greater than the exhaust pressure threshold, the controller can open the third electromagnetic valve 16 to intercommunicate the suction port and the exhaust port of the compressor 1, so as to quickly reduce the exhaust pressure and ensure stable operation of the heat pump system.

[0085] The specific value of the exhaust pressure threshold can be selected according to actual technical requirements. For example, in the embodiment, the exhaust pressure threshold is set to 3.8 Mpa.

[0086] It should be noted that after the liquid bypass branch is turned on by the controller, the controller can close the second electromagnetic valve 14 when the exhaust temperature drops to a closing temperature threshold, so as to shut off the liquid bypass branch. The closing temperature threshold is less than the exhaust temperature threshold. Similarly, after the gas bypass branch is turned on by the controller, the controller can close the third electromagnetic valve 16 when the exhaust pressure drops to a closing pressure threshold, so as to shut off the gas bypass branch. The closing pressure threshold is less than the exhaust pressure threshold.

[0087] In one exemplary embodiment, as shown in Figure 8 A heat pump system control method is provided, which is suitable for the heat pump system described in any of the above embodiments, and is executed by the controller in the heat pump system. The method comprises the following steps 202 to 208, wherein:

[0088] Step 202: obtaining an exhaust overheating degree according to the exhaust temperature and the exhaust pressure;

[0089] Step 204: determining an optional adjustment mode of the opening degree of the supplementary air throttling element according to the exhaust overheating degree, the adjustment mode at least comprising increasing, decreasing and keeping;

[0090] Step 206: obtaining an economizer overheating degree according to the auxiliary path inlet temperature and the auxiliary path outlet temperature;

[0091] Step 208: determining a target adjustment mode from the optional adjustment mode based on the economizer overheating degree, and controlling the opening degree of the supplementary air throttling element in the target adjustment mode.

[0092] The exhaust gas superheat degree is used to measure the degree to which the temperature of the compressed refrigerant gas is higher than the saturation temperature corresponding to the pressure thereof, and is crucial to ensuring stable operation of the compressor and the heat pump system. Specifically, the exhaust gas superheat degree can be determined by the exhaust gas temperature of the compressor and the outlet temperature of the condenser, or by the exhaust gas temperature of the compressor and the saturation temperature corresponding to the exhaust gas pressure. In the embodiments of the present application, for example, the saturation temperature corresponding to the exhaust gas pressure of the compressor can be calculated first, and then the exhaust gas superheat degree can be determined by the difference between the exhaust gas temperature and the saturation temperature corresponding to the exhaust gas pressure.

[0093] It can be understood that, if the exhaust gas superheat degree is too high, it indicates that the exhaust gas temperature is too high, i.e., the exhaust gas temperature is higher than the saturation temperature corresponding to the pressure thereof, which can cause an increase in the load of the compressor and an increase in power consumption, and can cause damage to the equipment or safety accidents. In this case, the supplementary gas throttling element can be effectively adjusted to make the liquid injection enthalpy-increasing branch divert more refrigerant circulation quantity, fully exert the heat exchange performance of the economizer, and reduce the exhaust gas temperature of the compressor to ensure that the exhaust gas superheat degree returns to the normal level. For example, the effective adjustment of the supplementary gas throttling element to make the liquid injection enthalpy-increasing branch divert more refrigerant circulation quantity can be limited to an increase in the opening degree of the supplementary gas throttling element.

[0094] If the exhaust gas superheat degree is too low, it indicates that the exhaust gas temperature is too low, i.e., the exhaust gas temperature is lower than the saturation temperature corresponding to the pressure thereof, which can cause a lack of refrigerant circulation quantity in the refrigerant circulation loop, and can cause the liquid return phenomenon, affect the oil separation effect, and even damage the compressor. Correspondingly, in this case, the supplementary gas throttling element can be effectively adjusted to reduce the refrigerant circulation quantity diverted by the liquid injection enthalpy-increasing branch, to ensure that there is sufficient refrigerant circulation quantity in the refrigerant circulation loop to maintain stable operation of the compressor. For example, the effective adjustment of the supplementary gas throttling element to reduce the refrigerant circulation quantity diverted by the liquid injection enthalpy-increasing branch can be limited to a decrease in the opening degree of the supplementary gas throttling element.

[0095] Of course, if the exhaust gas superheat degree is within the normal range, the optional adjustment mode of the opening degree of the supplementary gas throttling element can be any mode, and need not be limited. For example, the adjustment mode can be an increase, a decrease, or no change.

[0096] After determining the optional adjustment mode of the opening degree of the supplementary gas throttling element based on the exhaust gas superheat degree, the target adjustment mode is determined from the determined optional adjustment modes based on the economizer superheat degree, to adjust the opening degree of the supplementary gas throttling element according to the selected target adjustment mode.

[0097] The economizer superheat is the difference between the inlet temperature of the auxiliary path and the outlet temperature of the auxiliary path. Taking the economizer superheat as the reference basis for controlling the opening degree of the supplementary gas throttling element can ensure that the heat exchange capacity of the economizer is fully utilized, and can ensure that the refrigerant after passing through the main path of the economizer can obtain sufficient supercooling degree to improve the heat absorption capacity of the evaporator.

[0098] In one example embodiment, as shown in Figure 9 The heat pump system control method further includes the following steps 302 to 306, wherein:

[0099] In step 302, if the exhaust gas superheat is greater than a first exhaust gas superheat threshold, the optional adjustment mode of the opening degree of the supplementary gas throttling element includes increasing and maintaining.

[0100] In step 304, if the exhaust gas superheat is less than a second exhaust gas superheat threshold, the optional adjustment mode of the opening degree of the supplementary gas throttling element includes decreasing and maintaining.

[0101] In step 306, if the exhaust gas superheat is between the second exhaust gas superheat threshold and the first exhaust gas superheat threshold, the optional adjustment mode of the opening degree of the supplementary gas throttling element includes increasing, decreasing, and maintaining.

[0102] The first exhaust gas superheat threshold is greater than the second exhaust gas superheat threshold.

[0103] Specifically, the first exhaust gas superheat threshold is an upper threshold of the compressor exhaust gas superheat, and exceeding the threshold indicates that the exhaust gas superheat is high. The second exhaust gas superheat threshold is a lower threshold of the compressor exhaust gas superheat, and falling below the threshold indicates that the exhaust gas superheat is too low. The specific values of the first exhaust gas superheat threshold and the second exhaust gas superheat threshold are not limited, and can be determined comprehensively according to the type of the compressor, the working environment, and the load condition. For example, in the embodiments of the present application, the first exhaust gas superheat threshold can be set to 40℃, and the second exhaust gas superheat threshold can be set to 35℃.

[0104] Further, if the exhaust gas superheat is greater than the first exhaust gas superheat threshold, it indicates that the exhaust gas temperature exceeds the degree of the corresponding saturation temperature of the pressure, i.e., the exhaust gas temperature is high, which can cause the compressor load to increase and the power consumption to increase, which can cause equipment damage or safety accidents. Further, the optional adjustment mode of the opening degree of the supplementary gas throttling element includes increasing and maintaining, so that the liquid injection enthalpy increase branch obtains more refrigerant circulation amount, fully utilizes the heat exchange performance of the economizer, and reduces the compressor exhaust gas temperature to ensure that the compressor exhaust gas superheat returns to a normal level.

[0105] If the exhaust gas superheat degree is less than the second exhaust gas superheat threshold value, indicating that the exhaust gas temperature is lower than the saturation temperature corresponding to its pressure, it is determined that the refrigerant circulation amount in the refrigerant circulation loop is insufficient, which causes the exhaust gas temperature to be too low, and may cause the liquid return phenomenon, affecting the oil separation effect, and even damaging the compressor. Further, the optional adjustment mode of the opening of the charge throttling element can include reducing and maintaining, to reduce the refrigerant circulation amount obtained by the liquid injection enthalpy increase branch, and ensure that there is sufficient refrigerant circulation amount in the refrigerant circulation loop to maintain stable operation of the compressor.

[0106] If the exhaust gas superheat degree is between the second exhaust gas superheat threshold value and the first exhaust gas superheat threshold value, it is within the normal range, and the optional adjustment mode of the opening of the charge throttling element can be any mode without limitation, which can include increasing, decreasing, and maintaining.

[0107] In one exemplary embodiment, as shown in Figure 10 The heat pump system control method further includes steps 402 to 404, wherein:

[0108] Step 402, determining the current adjustment mode based on the comparison result of the economizer superheat degree and the target economizer superheat degree;

[0109] Step 404, if the current adjustment mode belongs to the optional adjustment mode, determining that the current adjustment mode is the target adjustment mode; otherwise, determining that the target adjustment mode is maintaining.

[0110] Specifically, the target economizer superheat degree is a target value that the desired economizer superheat degree maintains, which can be set based on the efficiency, stability, and risk of avoiding compressor liquid strike of the heat pump system. In this embodiment, the current adjustment mode can be determined based on the comparison result of the economizer superheat degree and the target economizer superheat degree, that is, whether the opening of the charge throttling element needs to be adjusted and how to adjust the opening of the charge throttling element to maintain the economizer superheat degree at the target economizer superheat degree.

[0111] Exemplarily, the controller is further configured to: if the economizer superheat degree meets the target economizer superheat degree, determining that the current adjustment mode is maintaining; if the economizer superheat degree exceeds the target economizer superheat degree, determining that the current adjustment mode is increasing; and if the economizer superheat degree is lower than the target economizer superheat degree, determining that the current adjustment mode is decreasing.

[0112] If the economizer superheat degree exceeds the target economizer superheat degree, it indicates that the refrigerant circulation amount obtained by the liquid injection enthalpy increase branch is insufficient, and to improve the heat exchange performance of the economizer, the current adjustment mode can be determined to be increasing. If the economizer superheat degree is lower than the target economizer superheat degree, it indicates that the refrigerant circulation amount obtained by the liquid injection enthalpy increase branch exceeds the heat exchange demand, and the current adjustment mode can be determined to be decreasing.

[0113] For example, the manner of determining whether the economizer superheat degree meets the target economizer superheat degree can be to calculate the difference between the economizer superheat degree and the target economizer superheat degree to obtain an economizer superheat degree difference. If the economizer superheat degree difference is within a preset difference range, it indicates that the economizer superheat degree meets the target economizer superheat degree. If the economizer superheat degree difference is greater than the preset difference range, it indicates that the economizer superheat degree exceeds the target economizer superheat degree. If the economizer superheat degree difference is less than the preset difference range, it indicates that the economizer superheat degree is lower than the target economizer superheat degree.

[0114] Further, after determining the current adjustment manner according to the economizer superheat degree, it is also necessary to match it with the optional adjustment manner to obtain the target adjustment manner, so as to ensure that the target adjustment manner meets the limitation requirement of the exhaust gas superheat degree. Specifically, in the case that the current adjustment manner belongs to the optional adjustment manner, the current adjustment manner is determined as the target adjustment manner; otherwise, the target adjustment manner is determined as maintaining. It can be understood that, if the adjustment manner determined according to the economizer superheat degree does not meet the limitation requirement of the exhaust gas superheat degree, the opening degree of the supplementary gas throttling element needs to be kept unchanged to avoid affecting the operation reliability of the compressor. If the adjustment manner determined according to the economizer superheat degree meets the limitation requirement of the exhaust gas superheat degree, the opening degree of the supplementary gas throttling element can be adjusted according to the current adjustment manner.

[0115] It needs to be noted that, in the case that the determined target adjustment manner is to increase or decrease, the supplementary gas throttling element can be adjusted by a fixed adjustment step until the economizer superheat degree meets the target economizer superheat degree. If the target adjustment manner is to increase and the opening degree of the supplementary gas throttling element has reached the maximum opening degree threshold, the current opening degree can be kept unchanged; if the target adjustment manner is to decrease and the opening degree of the supplementary gas throttling element has reached the minimum opening degree threshold, the current opening degree can be kept unchanged.

[0116] In addition, after adjusting the supplementary gas throttling element, the above-mentioned temperature and pressure parameters can be obtained again after waiting for an adjustment interval time length, and the exhaust gas superheat degree and the economizer superheat degree are analyzed to further determine whether the supplementary gas throttling element needs to be adjusted. In this embodiment, the adjustment interval time length is set during the adjustment of the supplementary gas throttling element, which can avoid frequent fluctuations of the system due to the opening degree adjustment of the throttling element, and is beneficial to ensure the operation stability of the heat pump system.

[0117] In an exemplary embodiment, the heat pump system control method further comprises: in the case that the exhaust gas superheat degree is between the second exhaust gas superheat degree threshold and the first exhaust gas superheat degree threshold and the economizer superheat degree is lower than the target economizer superheat degree, opening the first electromagnetic valve.

[0118] Specifically, when the exhaust gas superheat degree is between the second exhaust gas superheat threshold and the first exhaust gas superheat threshold, it indicates that the exhaust gas superheat degree is in the normal exhaust gas superheat degree range, and the economizer superheat degree is lower than the target economizer superheat degree, which indicates that the refrigerant circulation amount obtained by the liquid injection enthalpy increasing branch splitting is excessive, so as to avoid the risk of liquid compression caused by liquid from the liquid injection enthalpy increasing branch returning to the compression chamber of the compressor, the first electromagnetic valve needs to be opened to return the separated liquid refrigerant to the suction port of the compressor.

[0119] In one exemplary embodiment, the heat pump system control method further comprises: when the operation mode of the heat pump system is the heating mode, adjusting the opening degree of the second throttling element to the maximum opening degree threshold, and controlling the opening degree of the first throttling element; when the operation mode of the heat pump system is the cooling mode, adjusting the opening degree of the first throttling element to the maximum opening degree threshold, and controlling the opening degree of the second throttling element.

[0120] Specifically, the controller can control the opening degree of the first throttling element / second throttling element during the operation of the heat pump system according to the operating state of the compressor, so as to adjust the refrigerant circulation amount in the refrigerant circulation loop and ensure stable operation of the system in refrigeration and heating. The data basis for controlling the opening degree of the first throttling element / second throttling element is not unique, which can be controlled according to the suction superheat degree of the compressor and the target suction superheat degree, or according to the discharge superheat degree of the compressor and the target discharge superheat degree, or according to the operating parameters of the indoor heat exchanger or the outdoor heat exchanger, or according to any combination of the above operating parameters. It can be selected according to technical requirements as long as it can adjust the refrigerant circulation amount in the refrigerant circulation loop to ensure stable operation of the system in refrigeration and heating.

[0121] It should be understood that, although each step in the flowchart involved in each of the above-described embodiments is shown in sequence according to the arrow, these steps are not necessarily executed in sequence according to the arrow. Unless otherwise specified herein, the execution of these steps is not strictly limited in sequence, and these steps can be executed in other sequences. Moreover, at least part of the steps in the flowchart involved in each of the above-described embodiments can include multiple steps or stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution sequence of these steps or stages is not necessarily sequential, but can be executed alternately or alternately with at least part of other steps or steps or stages in other steps.

[0122] In one specific embodiment, as Figure 11 indicated, a heat pump system control method is provided to be applied to a heat pump system as Figure 12 indicated. Figure 7 indicated.

[0123] Specifically, the heat pump system comprises a refrigerant circulation loop formed by a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, a first throttling element 4, an economizer 5, and an indoor heat exchanger 6 connected by pipelines. It also comprises a liquid injection enthalpy-increasing branch, which makes the refrigerant branched from the refrigerant circulation loop flow into the gas supplement port of the compressor 1 through the auxiliary path of the economizer 5 between the main path of the economizer 5 and the first throttling element 4, and the liquid injection enthalpy-increasing branch is also provided with a gas supplement throttling element 7. It also comprises a first temperature sensor 8, a second temperature sensor 9, and a third temperature sensor 10 for obtaining the discharge temperature of the compressor 1, the inlet temperature and outlet temperature of the auxiliary path of the economizer 5, and a pressure sensor 11 for obtaining the discharge pressure of the compressor 1. The liquid injection enthalpy-increasing branch is also provided with a gas-liquid separation element 12 and a first electromagnetic valve 13, the refrigerant flowing out of the auxiliary path of the economizer 5 enters the gas-liquid separation element 12, the gaseous refrigerant obtained by separation is supplemented into the gas supplement port of the compressor 1, and the liquid refrigerant obtained by separation flows into the suction port of the compressor 1 through the first electromagnetic valve 13. The heat pump system also comprises a liquid bypass branch, which makes the refrigerant branched from the refrigerant circulation loop flow into the suction port of the compressor 1 between the indoor heat exchanger 6 and the main path of the economizer 5, and the liquid bypass branch is also provided with a second electromagnetic valve 14. The heat pump system also comprises a second throttling element 15 located between the indoor heat exchanger 6 and the main path of the economizer 5, wherein the first throttling element 4 and the second throttling element 15 are both one-way throttling valves. The heat pump system also comprises a gas bypass branch, which makes the refrigerant branched from the refrigerant circulation loop flow into the suction port of the compressor 1 from the discharge port of the compressor 1, and the gas bypass branch is also provided with a third electromagnetic valve 16.

[0124] Referring to Figure 11 With Figure 12 After the heat pump system is started in the refrigeration mode or the heating mode, the discharge pressure is first detected. If the discharge pressure is greater than 3.8 Mpa, the electromagnetic valve 1 (the third electromagnetic valve 16) is opened for gas bypassing to reduce the discharge pressure. Further, when the operating frequency of the compressor 1 is greater than a preset operating frequency (A) and reaches a preset time length (X), the discharge temperature is judged. When the discharge temperature is greater than a discharge temperature threshold value (100℃), the electromagnetic valve 2 (the second electromagnetic valve 14) is opened for liquid bypassing, and then the auxiliary electronic expansion valve (the gas supplement throttling element 7) is opened for liquid injection enthalpy-increasing to reduce the discharge temperature and improve the refrigeration and heating capacity. If the discharge temperature is less than or equal to the discharge temperature threshold value (100℃), the electromagnetic valve 2 is kept in the closed state, and the auxiliary electronic expansion valve is still opened to the minimum opening degree.

[0125] Then, the exhaust gas superheat degree of the compressor is judged. If the exhaust gas superheat degree is greater than a first exhaust gas superheat threshold (D, 40℃), the auxiliary electronic expansion valve is adjusted according to the economic superheat degree, but the auxiliary electronic expansion valve is only allowed to be opened, and the maximum value is the set maximum value. If the exhaust gas superheat degree is less than a second exhaust gas superheat threshold (C, 35℃), the auxiliary electronic expansion valve is adjusted according to the economic superheat degree, and is only allowed to be closed, and the minimum value is the set minimum value. If the exhaust gas superheat degree is between the second exhaust gas superheat threshold and the first exhaust gas superheat threshold, the auxiliary electronic expansion valve is freely adjusted according to the economic superheat degree.

[0126] In the process of adjusting the opening degree of the auxiliary electronic expansion valve according to the economic superheat degree, the difference between the current economic superheat degree and the target economic superheat degree can be first judged. If the difference between the current economic superheat degree and the target economic superheat degree is ≤-1, the opening degree of the current auxiliary electronic expansion valve is reduced and the electromagnetic valve 3 (the first electromagnetic valve 13) is opened. If the difference between the current economic superheat degree and the target economic superheat degree is ≥1, the opening degree of the current auxiliary electronic expansion valve is increased. If the difference between the current economic superheat degree and the target economic superheat degree is -1≤1, the opening degree of the current auxiliary electronic expansion valve is kept unchanged.

[0127] In the present embodiment, in the heat pump system, by setting the one-way main throttling element at both ends of the economizer and cooperating with the air supplement throttling element, the compressor is supplemented with air and the enthalpy is increased, and at the same time, the on-off of the second electromagnetic valve is used to spray liquid and gas to reduce the exhaust and improve the refrigeration and heating capacity. The opening degree of the air supplement throttling element is controlled by the exhaust superheat degree combined with the economizer superheat degree, which reduces the exhaust and improves the refrigeration and heating capacity while ensuring the reliability of the compressor. The heat pump system provided in the present application expands the use range of the system by combining the air bypass, liquid bypass and gas injection enthalpy control, and meets the user's comfort demand for refrigeration and heating.

[0128] The technical features of the above embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present application.

[0129] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be pointed out that for ordinary skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A heat pump system, characterized in that, The heat pump system includes: The refrigerant circulation loop allows the refrigerant to circulate in a loop consisting of a compressor, a four-way valve, an outdoor heat exchanger, a first throttling element, an economizer, and an indoor heat exchanger. The liquid injection enthalpy-increasing branch allows the refrigerant diverted from the refrigerant circulation loop to flow from the first throttling element and the main circuit of the economizer, through the auxiliary circuit of the economizer, into the compressor's gas inlet. The liquid injection enthalpy-increasing branch is also equipped with a gas inlet throttling element. A temperature sensing component is used to acquire the discharge temperature of the compressor, the auxiliary inlet temperature of the economizer, and the auxiliary outlet temperature. A pressure sensing element is used to obtain the discharge pressure of the compressor; The controller is configured as follows: The exhaust superheat is obtained based on the exhaust temperature and the exhaust pressure, and an optional adjustment method for the opening of the air-injection throttling element is determined based on the exhaust superheat. The adjustment method includes at least increasing, decreasing, and maintaining. The economizer superheat is obtained based on the auxiliary road inlet temperature and the auxiliary road outlet temperature. A target adjustment method is determined from the optional adjustment methods based on the economizer superheat, and the opening of the air-injection throttling element is controlled using the target adjustment method.

2. The heat pump system according to claim 1, characterized in that, The controller is also configured to: If the exhaust superheat is greater than the first exhaust superheat threshold, the selectable adjustment methods for the opening of the air supply throttling element include increasing and maintaining. If the exhaust superheat is less than the second exhaust superheat threshold, the selectable adjustment methods for the opening of the air supply throttling element include reducing and maintaining. If the exhaust superheat is between the second exhaust superheat threshold and the first exhaust superheat threshold, the selectable adjustment methods for the opening of the air supply throttling element include increasing, decreasing, and maintaining. Wherein, the first exhaust superheat threshold is greater than the second exhaust superheat threshold.

3. The heat pump system according to claim 2, characterized in that, The controller is also configured to: Based on the comparison between the overheating of the economizer and the target overheating of the economizer, the current adjustment mode is determined; If the current adjustment method belongs to the optional adjustment method, the current adjustment method is determined to be the target adjustment method; Otherwise, the target adjustment method is set to maintain.

4. The heat pump system according to claim 3, characterized in that, The controller is also configured to: If the overheat of the economizer meets the target overheat of the economizer, the current adjustment mode is determined to be maintenance. If the overheating of the economizer exceeds the target economizer overheating, the current adjustment mode is determined to be increased; If the overheating of the economizer is lower than the target economizer overheating, the current adjustment mode is determined to be reduced.

5. The heat pump system according to claim 2, characterized in that, The liquid injection enthalpy-increasing branch is also equipped with a gas-liquid separation element and a first solenoid valve. The refrigerant flowing out of the auxiliary circuit of the economizer enters the gas-liquid separation element. The separated gaseous refrigerant is added to the gas inlet of the compressor, and the separated liquid refrigerant flows into the suction port of the compressor through the first solenoid valve. The controller is also configured to: If the exhaust superheat is between the second exhaust superheat threshold and the first exhaust superheat threshold, and the economizer superheat is lower than the target economizer superheat, then the first solenoid valve is opened.

6. The heat pump system according to claim 1, characterized in that, The controller is also configured to: When the operating frequency of the compressor is greater than the preset operating frequency, the first time is recorded; When the first time exceeds the preset duration, the air supply throttling element is opened, and the opening degree of the air supply throttling element is adjusted to the minimum opening threshold.

7. The heat pump system according to claim 1, characterized in that, The heat pump system also includes: A liquid bypass branch allows refrigerant diverted from the refrigerant circulation loop to flow into the compressor's suction port between the indoor heat exchanger and the main economizer circuit. A second solenoid valve is also provided on the liquid bypass branch. The controller is also configured to: If the exhaust temperature is greater than the exhaust temperature threshold, the second solenoid valve is opened.

8. The heat pump system according to claim 1, characterized in that, The heat pump system also includes: The second throttling element is located between the indoor heat exchanger and the main circuit of the economizer, wherein both the first throttling element and the second throttling element are one-way throttling valves; The controller is also configured to: When the heat pump system is in heating mode, the opening degree of the first throttling element is controlled. When the heat pump system is operating in cooling mode, the opening degree of the second throttling element is controlled.

9. A heat pump system control method, applicable to the heat pump system as described in any one of claims 1 to 8, wherein the method is executed by the controller, characterized in that, The method includes: The exhaust superheat is obtained based on the exhaust temperature and exhaust pressure. The selectable adjustment method for the opening of the air supply throttling element is determined based on the exhaust superheat. The adjustment method includes at least increasing, decreasing, and maintaining. The superheat of the economizer is obtained based on the inlet and outlet temperatures of the auxiliary road. Based on the superheat of the economizer, a target adjustment mode is determined from the selectable adjustment modes, and the opening of the air supply throttling element is controlled according to the target adjustment mode.

10. The heat pump system control method according to claim 9, characterized in that, The method further includes: If the exhaust superheat is greater than the first exhaust superheat threshold, the selectable adjustment methods for the opening of the air supply throttling element include increasing and maintaining. If the exhaust superheat is less than the second exhaust superheat threshold, the selectable adjustment methods for the opening of the air supply throttling element include reducing and maintaining. If the exhaust superheat is between the second exhaust superheat threshold and the first exhaust superheat threshold, the selectable adjustment methods for the opening of the air supply throttling element include increasing, decreasing, and maintaining. Wherein, the first exhaust superheat threshold is greater than the second exhaust superheat threshold.

11. The heat pump system control method according to claim 10, characterized in that, The method further includes: Based on the comparison between the overheating of the economizer and the target overheating of the economizer, the current adjustment mode is determined; If the current adjustment method belongs to the optional adjustment method, the current adjustment method is determined to be the target adjustment method; Otherwise, the target adjustment method is set to maintain.

12. The heat pump system control method according to claim 10, characterized in that, The method further includes: If the exhaust superheat is between the second exhaust superheat threshold and the first exhaust superheat threshold, and the economizer superheat is lower than the target economizer superheat, then the first solenoid valve is opened.

13. The heat pump system control method according to claim 9, characterized in that, The method further includes: When the heat pump system is in heating mode, the opening degree of the first throttling element is controlled. When the heat pump system is operating in cooling mode, the opening degree of the second throttling element is controlled.

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