Four-way valve linkage control method, device, equipment and storage medium

Abstract

The application relates to the technical field of defrosting control, and discloses a four-way valve linkage control method, device, equipment and storage medium, which is used for solving the problem that the traditional four-way valve adjusting method is too rough, the defrosting mode is started in a low-temperature environment, stress concentration and liquid strike phenomena are prone to occur in the pipeline and the valve body, and the stability and service life of the low-temperature heat pump are affected. The four-way valve linkage control method comprises the following steps: in response to a defrosting mode starting instruction, it is judged whether the first heat pump operation parameter currently corresponding to the low-temperature heat pump meets the defrosting mode starting condition; if yes, the compressor is controlled to be reduced in frequency to a current high-low pressure differential pressure within a preset switching pressure differential range, and a target enthalpy increasing valve control strategy is determined according to the current environment temperature, the current water outlet temperature and a plurality of preset initial temperature enthalpy increasing valve control intervals; if not, the four-way valve is controlled to maintain a first target state; and the enthalpy increasing valve and the four-way valve are linkage controlled according to the target enthalpy increasing valve control strategy.

Description

Technical Field

[0001] The present application relates to the field of defrost control technology, and in particular to a four-way valve linkage control method, device, equipment and storage medium. Background Art

[0002] Low-temperature heat pumps can meet the heating needs of areas with low ambient temperatures. They generally use jet enthalpy increase technology, that is, by adding an air intake in the middle of the compressor and adjusting the refrigerant flow entering the compressor through an enthalpy increase valve to improve the energy efficiency of the unit, and changing the refrigerant flow direction through a four-way valve to achieve switching between cooling and heating. In the heating mode, the evaporator of the outdoor unit of the low-temperature heat pump is prone to frost and hinders the heat exchange. When the defrost conditions are met, the four-way valve is switched to run the defrost mode to restore the heat exchange efficiency of the evaporator and improve the overall heating performance of the system.

[0003] The switching control of traditional valves usually controls the switching of the four-way valve when the operating frequency of the variable-frequency compressor drops to a certain threshold. If it is a fixed-frequency compressor, the four-way valve is controlled to switch when the defrost conditions are met. However, the rapid switching of the four-way valve in the defrost mode will easily cause stress concentration inside the pipeline and valve body. In an ultra-low temperature environment, if the adjustment of the enthalpy increase valve fails to adapt to the sudden change in the refrigerant flow direction, the refrigerant will impact the four-way valve, causing component fatigue, cracking or even breakage under long-term operation, affecting the stability of the low-temperature heat pump and shortening its service life. Summary of the Invention

[0004] The present application provides a four-way valve linkage control method, device, equipment and storage medium, which are used in situations where the traditional four-way valve adjustment method is too rough. Entering the defrost mode in a low-temperature environment will easily cause stress concentration and liquid hammer inside the pipeline and valve body, affecting the stability of the low-temperature heat pump and shortening its service life.

[0005] The first aspect of the present application provides a four-way valve linkage control method, which is applied to a low-temperature heat pump, including: responding to a defrost mode start instruction, judging whether the first heat pump operating parameters currently corresponding to the low-temperature heat pump meet the defrost mode start conditions; if so, controlling the compressor to reduce the frequency to the current high and low pressure difference within the preset switching pressure difference range, and determining the target enthalpy increase valve control strategy based on the current ambient temperature, the current water outlet temperature and the preset multiple initial temperature enthalpy increase valve control intervals, otherwise controlling the four-way valve to maintain the first target state; based on the target enthalpy increase valve control strategy, the enthalpy increase valve and the four-way valve are linked and controlled, and the four-way valve is switched to the second target state; when the second heat pump operating parameters currently corresponding to the low-temperature heat pump meet the defrost mode exit conditions, controlling the four-way valve to switch to the first target state.

[0006] The second aspect of the present application provides a four-way valve linkage control device, including: a judgment module, used to respond to the defrost mode start instruction to determine whether the first heat pump operating parameters currently corresponding to the low-temperature heat pump meet the defrost mode start conditions; a processing module, used to, if so, control the compressor to reduce the frequency to the current high and low pressure difference within the preset switching pressure difference range, and determine the target enthalpy increase valve control strategy based on the current ambient temperature, the current water outlet temperature and the preset multiple initial temperature enthalpy increase valve control intervals, otherwise control the four-way valve to maintain the first target state; a linkage control module, used to linkage control the enthalpy increase valve and the four-way valve based on the target enthalpy increase valve control strategy, and the four-way valve switches to the second target state; an exit control module, used to control the four-way valve to switch to the first target state when the second heat pump operating parameters currently corresponding to the low-temperature heat pump meet the defrost mode exit conditions.

[0007] The third aspect of the present application provides a four-way valve linkage control device, comprising: a memory and at least one processor, wherein the memory stores instructions; the at least one processor calls the instructions in the memory so that the four-way valve linkage control device executes the above-mentioned four-way valve linkage control method.

[0008] A fourth aspect of the present application provides a computer-readable storage medium, wherein the computer-readable storage medium stores instructions, which, when executed on a computer, enable the computer to execute the above-mentioned four-way valve linkage control method.

[0009] In the technical solution provided in the present application, whether the operating parameters of the first heat pump meet the starting conditions of the defrost mode is determined to avoid stress concentration caused by starting the defrost when the frost layer is too thick or unevenly distributed. The current high and low pressure difference of the compressor is controlled by frequency reduction to be within the allowable switching pressure difference range, thereby ensuring the pressure stability of the refrigerant during the switching process and avoiding stress increase due to sudden pressure change. The target enthalpy increase valve control strategy is determined by the current ambient temperature and the current water outlet temperature to achieve joint control of the enthalpy increase valve and the four-way valve under extreme working conditions, avoid reducing the impact of the refrigerant switching on the four-way valve, and achieve precise control of the four-way valve under the defrost operation of the low-temperature heat pump, thereby reducing the probability of stress concentration and liquid hammer, extending the service life of the four-way valve, and improving the stability of the low-temperature heat pump. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a schematic diagram of an embodiment of the four-way valve linkage control method of the present application;

[0011] Figure 2 This is a schematic diagram of another embodiment of the four-way valve linkage control method of the present application;

[0012] Figure 3 This is a schematic diagram of an embodiment of the four-way valve linkage control device of the present application;

[0013] Figure 4 Fig. 4 is a schematic diagram of another embodiment of the four-way valve linkage control device of the present application.

[0014] Figure 5 Fig. 4 is a schematic diagram of another embodiment of the four-way valve linkage control device of the present application. DETAILED DESCRIPTION

[0015] The present application provides a four-way valve linkage control method, device, equipment and storage medium, for the traditional four-way valve adjustment method is too rough, low temperature environment, start defrosting mode, will lead to pipe and valve body inside easy to produce stress concentration and liquid strike phenomenon, affect the stability and service life of low temperature heat pump.

[0016] The terms "first", "second", "third", "fourth" and the like in the description and in the claims of the present application, if any, are used for distinguishing between similar objects talking about and do not necessarily have to follow a specific sequential order. It is to be understood that the use of these terms herein is merely used as a label to distinguish between the similar objects, and should in no way limit the scope of the application unless explicitly indicated. Moreover, the terms "comprising", "having", "including", and the like, if any, are used herein in their open-ended, non-limiting sense to encompass the presence of one or more elements, steps, or units, but do not preclude the presence or addition of one or more other elements, steps, or units not expressly listed or inherent to such process, method, system, product, or apparatus. Furthermore, these terms do not exclude the presence or addition of other diverse elements, steps, or units with respect to such processes, methods, systems, products, or apparatus.

[0017] For the sake of understanding, the specific flow of the embodiments of the present application is described below. Please refer to Figure 1 One embodiment of the four-way valve linkage control method in the embodiments of the present application includes:

[0018] 101, in response to the defrosting mode start instruction, judge whether the first heat pump operation parameter corresponding to the low temperature heat pump at present meets the defrosting mode start condition.

[0019] It can be understood that the execution subject of the present application can be a four-way valve linkage control device, but also a low temperature heat pump terminal or server, and the specific execution subject is not limited here. The embodiments of the present application take the low temperature heat pump as the execution subject for example.

[0020] The low-temperature heat pump of the embodiment comprises a heat exchanger, a compressor, a fan, a four-way valve and an enthalpy increasing valve, wherein the heat exchanger is used for heat transfer and exchange, for example, in the heating mode, the refrigerant evaporates by absorbing the heat of the outside (such as air or water) through the heat exchanger and releases heat to the target medium (such as hot water or indoor air), and in the low-temperature working condition, frost is easy to appear on the heat exchanger, especially the frost on the outdoor unit in the low-temperature working condition affects the heat exchange between the refrigerant and the outside, reduces the COP of the unit, and even causes damage to the unit. Therefore, in order to solve the negative effects caused by the frost, the heat pump unit usually needs to perform defrosting operation.

[0021] The compressor compresses the low-temperature and low-pressure refrigerant gas into high-temperature and high-pressure refrigerant gas to circulate the refrigerant, the fan is used to increase the air flow speed and improve the heat exchange efficiency of the heat exchanger, and the enthalpy increasing valve is used to adjust the flow of the refrigerant supplied to the air supplement port of the compressor to reduce the temperature of the intermediate cavity and improve the energy efficiency of the low-temperature heat pump. The four-way valve is used to change the circulation direction of the refrigerant, so that the heat pump can switch between the cooling and heating modes, and the defrosting mode is to control the four-way valve to switch from the heating mode to the cooling mode to realize the process of inverse circulation of the refrigerant and melting of the frost layer by using the heat of the refrigerant.

[0022] Specifically, the low-temperature heat pump acquires the first heat pump running parameter corresponding to the current time in response to the defrosting mode starting instruction, and judges whether the first heat pump running parameter meets the defrosting mode starting condition.

[0023] It needs to be further explained that the four-way valve linkage control method of the embodiment is a judgment executed in response to the defrosting mode starting instruction, that is, the defrosting operation needs to be performed at this time, and the above-mentioned defrosting mode starting condition is to avoid stress concentration caused by four-way valve switching in the case of too thick and unevenly distributed frost layer. That is, the defrosting mode starting condition of the embodiment can include appropriate frost layer thickness, and the defrosting mode starting condition can also include evenly distributed frost layer.

[0024] The first heat pump running parameter can be used to indicate the running state parameter of the current frost degree, that is, the heat pump state parameter used to judge whether the frost layer thickness is appropriate and / or the frost layer is evenly distributed. The first heat pump running parameter can include one or more of the first heat exchanger temperature, the first low-pressure pressure value, the first fan current, the first heat exchanger image, the first fan power and the like.

[0025] The above-mentioned first heat exchanger temperature can be collected by the temperature sensor arranged on the heat exchanger. The more serious the frost degree of the heat exchanger is, such as the thicker the frost layer is and the larger the frost layer coverage area is, the lower the collected heat exchanger temperature is.

[0026] The above-mentioned first low-pressure pressure value can be collected by the pressure sensor installed at the inlet of the compressor, that is, the low-pressure side pressure sensor. The more serious the frost degree is, the lower the low-pressure pressure value is.

[0027] The first fan current value can be collected by a current sensor connected to the fan, and the first fan power can be directly collected by a power sensor. If the degree of frost is more severe, the first fan current value and the first fan power will both increase.

[0028] The above-mentioned first heat exchanger image can be collected by an image acquisition device set on the heat exchanger, and can be used to indicate the frost situation on the heat exchanger through image processing technology, such as frost layer thickness, frost distribution, frost layer coverage area, etc.

[0029] It can be understood that the defrost mode start instruction can be manually triggered by the user or automatically triggered by the low-temperature heat pump according to the corresponding defrost control logic. The above-mentioned first heat pump operating parameters can also include other parameters, and the method of obtaining each parameter can also be collected according to actual conditions. This embodiment does not impose specific restrictions.

[0030] 102. If so, control the compressor to reduce frequency until the current high and low pressure difference is within the preset switching pressure difference range, and determine the target enthalpy increase valve control strategy based on the current ambient temperature, the current outlet water temperature and the preset multiple initial temperature enthalpy increase valve control intervals; otherwise, control the four-way valve to maintain the first target state.

[0031] Specifically, if the operating parameters of the first heat pump meet the starting conditions of the defrost mode, that is, the current frost layer thickness is moderate and the frost layer is evenly distributed, the compressor is controlled to reduce the frequency until the current high and low pressure difference is within the preset switching pressure difference range, and the target enthalpy increase valve control strategy is determined based on the current ambient temperature, the current water outlet temperature and the preset multiple initial temperature enthalpy increase valve control intervals; if the operating parameters of the first heat pump do not meet the starting conditions of the defrost mode, that is, the current frost layer is too thick and / or the frost layer is evenly distributed, the four-way valve is controlled to maintain the first target state.

[0032] In this embodiment, the first target state is used to indicate the state of the four-way valve when it is in the heating mode, that is, the four-way valve is not switched, and the second target state is used to indicate the state of the four-way valve when it is in the cooling mode. When the four-way valve is switched from the first target state to the second target state, the refrigerant flows back to realize the defrosting operation, and then switches from the second target state to the first target state to end the defrosting and continue to execute the heating mode.

[0033] The above-mentioned switching pressure difference range is used to indicate the high and low pressure difference interval from the lowest switching pressure difference to the highest switching pressure difference. When the current high and low pressure difference is within the preset switching pressure difference range, the four-way valve can switch smoothly and there will be no excessive stress. If the current high and low pressure difference is less than the lowest switching pressure difference, the four-way valve pressure difference will be insufficient and the switching will fail. If the current high and low pressure difference is greater than the highest switching pressure difference, stress concentration will occur.

[0034] It can be understood that in the process of compressor frequency reduction, the high and low pressure differential of the compressor gradually balances, that is, in the process of compressor frequency reduction, the high pressure of the compressor gradually decreases, and the low pressure of the compressor gradually increases. When the compressor stops, the high pressure of the compressor and the low pressure of the compressor are consistent, and the high and low pressure differential of the compressor is balanced. The time from the compressor frequency reduction to the stop is the balance time of the compressor. The high and low pressure differential of the compressor is positively correlated with the high and low of the operating frequency of the compressor. The higher the frequency, the greater the differential, and the more balance time is needed for high and low pressure balance. Too large differential will cause impact on the valve body of the four-way valve and increase the risk of hardware damage.

[0035] Optionally, the above determining the target enthalpy-increasing valve control strategy according to the current environment temperature, the current outlet water temperature and the preset plurality of initial temperature enthalpy-increasing valve control intervals comprises: screening according to the current environment temperature in the preset plurality of initial temperature enthalpy-increasing valve control intervals to obtain a plurality of candidate temperature enthalpy-increasing valve control intervals; and determining the target temperature enthalpy-increasing valve control interval according to the current outlet water temperature in the plurality of candidate temperature enthalpy-increasing valve control intervals.

[0036] Optionally, the plurality of initial temperature enthalpy-increasing valve control intervals can also be represented by a temperature enthalpy-increasing valve control table. For example, the temperature enthalpy-increasing valve control table shown in Table 1 includes six initial temperature enthalpy-increasing valve control intervals. The target temperature enthalpy-increasing valve control interval is determined according to the current environment temperature and the current outlet water temperature in the temperature enthalpy-increasing valve control table, and the target enthalpy-increasing valve control strategy is obtained.

[0037] Table 1

[0038]

[0039] wherein, T E is used to indicate the current environment temperature, T E_th is the set environment temperature threshold under low temperature working condition, T E_th is less than 0 degrees Celsius, which can be set to -20 degrees Celsius or other values, T out represents the outlet water temperature, T out_th is the set outlet water temperature threshold, t1>t2>t3, t4>t5, t1>t4, t5>t2, and t1 is less than or equal to the preset four-way valve switching period.

[0040] The embodiment adjusts the enthalpy-increasing valve under different environment temperatures and outlet water temperatures under low temperature working condition. The lower the outlet water temperature and the higher the environment temperature, the earlier the enthalpy-increasing valve can be closed to ensure system stability.

[0041] It should be further explained that the above temperature increase enthalpy valve control table is only an example, wherein the number of temperature increase enthalpy valve control intervals and the temperature increase enthalpy valve control strategy corresponding to each temperature increase enthalpy valve control interval can be set according to actual conditions, and the present embodiment is not specifically limited.

[0042] 103、Based on the target enthalpy valve control strategy, the enthalpy valve and the four-way valve are linked and controlled, and the four-way valve is switched to the second target state.

[0043] If the target enthalpy valve control strategy includes a target early closing period, the enthalpy valve is controlled to close early according to the running time of the compressor at the target frequency, the target early closing period and the preset switching period, and the four-way valve is switched to the second target state when the running time reaches the preset switching period. The target early closing period is the first preset time or the second preset time. If the target enthalpy valve control strategy is to maintain the current opening degree adjustment, the enthalpy valve is controlled to maintain the current opening degree, and the four-way valve is switched to the second target state when the running time reaches the preset switching period.

[0044] It can be understood that the target early closing period will be relative to the time when the enthalpy valve is controlled before the four-way valve is switched, and the time when the compressor runs at the target frequency will first reach the target early closing period to close the enthalpy valve, and then reach the switching period, that is, the time when the high-low pressure difference is within the preset switching pressure difference range, that is, the four-way valve can be switched for defrosting, so as to ensure the stability of the low-temperature heat pump and avoid frequent switching.

[0045] For ease of understanding, an example is provided, the target early closing period is 50 seconds, and the switching period is 60 seconds. The compressor of the low-temperature heat pump reaches the preset target frequency (such as 40 Hz) at 20:00:00 of the built-in clock, at this time, the high-low pressure difference of the compressor is within the preset switching pressure difference range;

[0046] According to the current time, the target early closing period and the switching period, the enthalpy valve closing time is determined to be 20:00:10, and the four-way valve switching time is determined to be 20:00:60;

[0047] The compressor continues to run at the target frequency until the built-in clock reaches 20:00:10 to control the enthalpy valve to close, and continues to run until the built-in clock reaches 20:00:60 to control the four-way valve to switch to the second target state.

[0048] 104、When the current second heat pump operating parameter of the low-temperature heat pump meets the defrosting mode exit condition, the four-way valve is controlled to switch to the first target state.

[0049] The second heat pump operating parameter of this embodiment is used to indicate the heat pump state parameter after the defrost operation is completed, and can be used to indicate the operating state parameter of the current frosting degree, that is, the second heat pump operating parameter is used to determine whether the defrost operation has been completed.

[0050] The second heat pump operating parameters and the first heat pump operating parameters are used to represent the operating state parameters before and after defrosting. The second heat pump operating parameters may be one or more of the first heat pump operating parameters, and this embodiment does not impose any specific restrictions.

[0051] In the embodiment of the present application, whether the operating parameters of the first heat pump meet the starting conditions of the defrost mode is determined to avoid stress concentration caused by starting the defrost when the frost layer is too thick or unevenly distributed. The current high and low pressure difference of the compressor is controlled by frequency reduction to be within the allowable switching pressure difference range to ensure the pressure stability of the refrigerant during the switching process and avoid stress increase caused by sudden pressure change. The target enthalpy increase valve control strategy is determined by the current ambient temperature and the current water outlet temperature to achieve joint control of the enthalpy increase valve and the four-way valve under extreme working conditions, avoid reducing the impact of the refrigerant switching on the four-way valve, and achieve precise control of the four-way valve under the defrost operation of the low-temperature heat pump, thereby reducing the probability of stress concentration and liquid hammer, extending the service life of the four-way valve, and improving the stability of the low-temperature heat pump.

[0052] See also Figure 2 Another embodiment of the four-way valve linkage control method in the embodiment of the present application includes:

[0053] 201. In response to a defrost mode start instruction, determine whether a first heat pump operating parameter currently corresponding to a low-temperature heat pump meets a defrost mode start condition.

[0054] Specifically, in response to the defrost mode start instruction, the first heat pump operating parameters currently corresponding to the low-temperature heat pump are obtained, and the first heat pump operating parameters include the first heat exchanger temperature, the first low-pressure value and the first fan current value; if the first heat exchanger temperature is greater than the preset first temperature threshold, the first low-pressure value is greater than the preset first low-pressure threshold, and the first fan current value is less than the preset first current threshold, it is determined that the defrost mode start condition is met, otherwise it is determined that the defrost mode start condition is not met.

[0055] If the temperature of the first heat exchanger is less than or equal to the preset first temperature threshold, and / or the first low-pressure value is less than or equal to the preset first low-pressure threshold, and / or the first fan current value is greater than or equal to the preset first current threshold, it is determined that the start-up conditions of the defrost mode are not met. At this time, the frost layer is too thick and it is not appropriate to perform defrost operation by switching the four-way valve.

[0056] It can be understood that in this embodiment, when the first heat exchanger temperature, the first low pressure value, and the first fan current value all meet the above settings, it is determined that the defrost mode start-up conditions are met. When any one parameter does not meet the above settings, it is determined that the defrost mode start-up conditions are not met. This can avoid entering the four-way valve switching when the frost layer is too thick or unevenly distributed, thereby improving the durability of the four-way valve.

[0057] 202. If so, control the compressor to reduce frequency until the current high and low pressure difference is within the preset switching pressure difference range, and determine the target enthalpy increase valve control strategy based on the current ambient temperature, the current outlet water temperature and the preset multiple initial temperature enthalpy increase valve control intervals; otherwise, control the four-way valve to maintain the first target state.

[0058] In this embodiment, the multiple initial temperature enthalpy increase valve control intervals include at least one enthalpy increase closing interval and at least one enthalpy increase maintaining interval, wherein the enthalpy increase valve control strategy in the enthalpy increase maintaining interval is to maintain the current enthalpy increase valve opening, and the enthalpy increase valve is adjusted according to other opening adjustment strategies. For example, the enthalpy increase valve is closed when the compressor is shut down, and the enthalpy increase valve control strategy in the enthalpy increase closing interval is to close the enthalpy increase valve before the four-way valve is closed. By adjusting the enthalpy increase valve in advance, the refrigerant circulation volume of the compressor is reduced, and the impact of the refrigerant switching on the four-way valve is reduced.

[0059] Specifically, when the first heat pump operating parameters meet the defrost mode start-up conditions, the compressor is controlled to reduce the frequency until the current high and low pressure difference is within the preset switching pressure difference range, and the timing is started when the compressor is reduced to the target frequency; if the current ambient temperature and the current outlet water temperature are in any enthalpy increase maintenance interval, the target enthalpy increase valve control strategy is determined to maintain the current opening adjustment; if the current ambient temperature and the current outlet water temperature are in any enthalpy increase closing interval, the target enthalpy increase valve control strategy is determined to close the enthalpy increase valve according to the target early closing cycle.

[0060] To facilitate understanding, an example is provided with multiple initial temperature enthalpy increase valve control intervals:

[0061] (1) When the ambient temperature is greater than 0°C and the outlet water temperature is less than or equal to 50°C, the enthalpy increasing valve is closed for a first preset time in advance, such as 60 seconds in advance;

[0062] (2) -25℃<ambient temperature≤0℃, outlet water temperature≤50℃, close the enthalpy increasing valve for a second preset time in advance, such as closing the enthalpy increasing valve 50 seconds in advance;

[0063] (3) When the ambient temperature is ≤-25°C and the outlet water temperature is ≤50°C, the enthalpy increasing valve is closed for a third preset time in advance, such as 40 seconds in advance;

[0064] (4) When the ambient temperature is greater than 0°C and the outlet water temperature is greater than 50°C, the enthalpy increasing valve is closed a fourth preset time in advance, such as 30 seconds in advance;

[0065] (5) When the ambient temperature is ≤0℃ and the outlet water temperature is >50℃, maintain the current opening adjustment.

[0066] This embodiment adjusts the enthalpy increasing valve in advance according to the ambient temperature and the outlet water temperature, reduces the refrigerant circulation volume of the compressor, and reduces the impact of the refrigerant switching on the four-way valve. The lower the outlet water temperature and the higher the ambient temperature, the easier it is to obtain liquid for enthalpy increasing and the exhaust control is difficult, so the enthalpy increasing valve can be closed a little in advance.

[0067] 203. Based on the target enthalpy increasing valve control strategy, the enthalpy increasing valve and the four-way valve are controlled in linkage, and the four-way valve is switched to the second target state.

[0068] Specifically, if the target enthalpy increasing valve control strategy includes a target early closing period, the enthalpy increasing valve is controlled to close in advance according to the operating time of the compressor at the target frequency, the target early closing period, and the preset switching period, and the four-way valve is controlled to switch to the second target state when the operating time reaches the preset switching period;

[0069] If the target enthalpy increasing valve control strategy is to maintain the current opening adjustment, the enthalpy increasing valve is controlled to maintain the current opening, and the four-way valve is controlled to switch to the second target state when the operating time reaches the preset switching cycle.

[0070] If the above-mentioned target enthalpy increasing valve control strategy includes a target early closing period, then the early closing of the enthalpy increasing valve is controlled according to the operating time of the compressor at the target frequency, the target early closing period and the preset switching period, including: determining the four-way valve switching moment according to the first moment corresponding to when the compressor is reduced to the target frequency and the preset switching period; determining the closing moment of the enthalpy increasing valve according to the four-way valve switching moment and the target early closing period; and controlling the enthalpy increasing valve to close when the closing moment of the enthalpy increasing valve is reached.

[0071] The above-mentioned target early closing period and switching period can be the same, that is, when the compressor drops to the target frequency, the enthalpy increasing valve is closed immediately, and when the compressor runs at the target frequency for a period of time equal to the switching period, the four-way valve is controlled to switch; the target early closing period and switching period can also be different. When the compressor drops to the target frequency and runs to the target early closing period, the enthalpy increasing valve is closed, and when the compressor is at the target frequency, it continues to run for a period of time equal to the switching period, and then the four-way valve is controlled to switch.

[0072] 204. When the second heat pump operating parameter currently corresponding to the low-temperature heat pump meets the defrost mode exit condition, control the four-way valve to switch to the first target state.

[0073] acquire a second heat pump operating parameter corresponding to the low-temperature heat pump currently, the second heat pump operating parameter includes at least one parameter of a second heat exchanger temperature, a second low-pressure pressure value and a second fan current value;If the second heat exchanger temperature is greater than a preset second temperature threshold value, and / or the second low-pressure pressure value is greater than a preset second low-pressure threshold value, and / or the first fan current value is less than a preset second current threshold value, then control the four-way valve to switch to a first target state.

[0074] In the embodiment, when one of the second heat exchanger temperature, the second low-pressure pressure value and the second fan current value meets the defrost mode exit condition, the four-way valve is controlled to switch to the first target state to exit the defrost mode.

[0075] 205、If the first heat pump operating parameter does not meet the defrost mode start condition, then control the four-way valve to maintain the first target state, and start an auxiliary defrost mode.

[0076] The low-temperature heat pump unit of the embodiment further includes an auxiliary heating device, and when the first heat pump operating parameter does not meet the defrost mode start condition, switching the four-way valve for defrosting will cause stress concentration, and the embodiment defrosts by starting the auxiliary heating device to prolong the service life of the four-way valve.

[0077] Specifically, if the first heat pump operating parameter does not meet the defrost mode start condition, then control the auxiliary heating device to defrost, and start timing;When the auxiliary heating time reaches a preset auxiliary heating time length, and / or the third heat pump operating parameter meets the defrost mode start condition, turn off the auxiliary heating device.

[0078] In the embodiment, whether the first heat pump operating parameter meets the defrost mode start condition is used to avoid switching the four-way valve when the frost layer is too thick or unevenly distributed, and defrosting is performed by starting the auxiliary heating device;When the first heat pump operating parameter meets the defrost mode start condition, the current high-low pressure difference of the compressor is controlled to be within the allowable switching pressure difference range by frequency reduction, to ensure the stability of the refrigerant pressure during switching, avoid stress increase due to pressure sudden change, and determine the target enthalpy valve control strategy according to the current environment temperature and the current water outlet temperature, to realize the joint control of the enthalpy valve and the four-way valve under extreme conditions, avoid the impact of refrigerant switching moment on the four-way valve, realize the precise control of the four-way valve under the low-temperature heat pump defrosting operation, reduce the probability of stress concentration and liquid knock, prolong the service life of the four-way valve, and improve the stability of the low-temperature heat pump.

[0079] The four-way valve linkage control method in the embodiment is described above, and the four-way valve linkage control device in the embodiment is described below, please refer to Figure 3 An embodiment of the four-way valve linkage control device in the embodiment includes:

[0080] The judgment module 301 is used to judge whether the first heat pump operating parameter currently corresponding to the low-temperature heat pump meets the defrost mode starting condition in response to the defrost mode starting instruction;

[0081] Processing module 302 is configured to, if yes, control the compressor to reduce frequency until the current high and low pressure differential is within a preset switching pressure differential range, and determine a target enthalpy increasing valve control strategy based on the current ambient temperature, the current outlet water temperature, and a plurality of preset initial temperature enthalpy increasing valve control intervals; otherwise, control the four-way valve to maintain the first target state;

[0082] A linkage control module 303 is configured to perform linkage control on the enthalpy increasing valve and the four-way valve based on the target enthalpy increasing valve control strategy, so that the four-way valve switches to a second target state;

[0083] The exit control module 304 is configured to control the four-way valve to switch to the first target state when the second heat pump operating parameter currently corresponding to the low-temperature heat pump meets the defrost mode exit condition.

[0084] In the embodiment of the present application, whether the operating parameters of the first heat pump meet the starting conditions of the defrost mode is determined to avoid stress concentration caused by starting the defrost when the frost layer is too thick or unevenly distributed. The current high and low pressure difference of the compressor is controlled by frequency reduction to be within the allowable switching pressure difference range to ensure the pressure stability of the refrigerant during the switching process and avoid stress increase caused by sudden pressure change. The target enthalpy increase valve control strategy is determined by the current ambient temperature and the current water outlet temperature to achieve joint control of the enthalpy increase valve and the four-way valve under extreme working conditions, avoid reducing the impact of the refrigerant switching on the four-way valve, and achieve precise control of the four-way valve under the defrost operation of the low-temperature heat pump, thereby reducing the probability of stress concentration and liquid hammer, extending the service life of the four-way valve, and improving the stability of the low-temperature heat pump.

[0085] See also Figure 4 Another embodiment of the four-way valve linkage control device in the embodiment of the present application includes:

[0086] The judgment module 301 is used to judge whether the first heat pump operating parameter currently corresponding to the low-temperature heat pump meets the defrost mode starting condition in response to the defrost mode starting instruction;

[0087] Processing module 302 is configured to, if yes, control the compressor to reduce frequency until the current high and low pressure differential is within a preset switching pressure differential range, and determine a target enthalpy increasing valve control strategy based on the current ambient temperature, the current outlet water temperature, and a plurality of preset initial temperature enthalpy increasing valve control intervals; otherwise, control the four-way valve to maintain the first target state;

[0088] A linkage control module 303 is configured to perform linkage control on the enthalpy increasing valve and the four-way valve based on the target enthalpy increasing valve control strategy, so that the four-way valve switches to a second target state;

[0089] The exit control module 304 is configured to control the four-way valve to switch to the first target state when the second heat pump operating parameter currently corresponding to the low-temperature heat pump meets the defrost mode exit condition.

[0090] Optionally, the processing module 302 is specifically configured to: when the operating parameters of the first heat pump meet the defrost mode start condition, control the compressor to reduce the frequency until the current high and low pressure difference is within a preset switching pressure difference range, and determine to start timing when the compressor frequency is reduced to the target frequency;

[0091] If the current ambient temperature and the current outlet water temperature are in any enthalpy increase maintenance interval, the target enthalpy increase valve control strategy is determined to maintain the current opening adjustment;

[0092] If the current ambient temperature and the current outlet water temperature are in any enthalpy increase closing interval, the target enthalpy increase valve control strategy is determined to close the enthalpy increase valve according to the target early closing period, and the first preset time is greater than the second preset time.

[0093] Optionally, the linkage control module 303 is specifically configured to: if the target enthalpy increasing valve control strategy includes a target early closing period, control the enthalpy increasing valve to close in advance according to the operating time of the compressor at the target frequency and the target early closing period, and control the four-way valve to switch to the second target state when the operating time reaches a preset switching period;

[0094] If the target enthalpy increasing valve control strategy is to maintain the current opening adjustment, the enthalpy increasing valve is controlled to maintain the current opening, and the four-way valve is controlled to switch to the second target state when the operating time reaches the preset switching period.

[0095] Optionally, the judgment module 301 is specifically configured to: in response to a defrost mode start instruction, obtain first heat pump operating parameters currently corresponding to the low-temperature heat pump, the first heat pump operating parameters including a first heat exchanger temperature, a first low pressure value, and a first fan current value;

[0096] If the first heat exchanger temperature is greater than the preset first temperature threshold, the first low pressure value is greater than the preset first low pressure threshold, and the first fan current value is less than the preset first current threshold, it is determined that the defrost mode start-up conditions are met; otherwise, it is determined that the defrost mode start-up conditions are not met.

[0097] Optionally, the exit control module 304 is specifically configured to: obtain a second heat pump operating parameter currently corresponding to the low-temperature heat pump, the second heat pump operating parameter including at least one of a second heat exchanger temperature, a second low pressure value, and a second fan current value;

[0098] If the second heat exchanger temperature is greater than the preset second temperature threshold, and / or the second low pressure value is greater than the preset second low pressure threshold, and / or the first fan current value is less than the preset second current threshold, the four-way valve is controlled to switch to the first target state.

[0099] Optionally, the four-way valve linkage control device further includes: an auxiliary defrost module 305, which is used to control the four-way valve to maintain the first target state and start the auxiliary defrost mode if the first heat pump operating parameters do not meet the defrost mode start conditions.

[0100] Optionally, the auxiliary defrost module 305 is specifically configured to control the auxiliary heating device to perform defrost and start timing if the operating parameters of the first heat pump do not meet the defrost mode start conditions;

[0101] When the auxiliary heating time reaches a preset auxiliary heating time, and / or the third heat pump operation parameter meets the defrost mode start condition, the auxiliary heating device is turned off.

[0102] In an embodiment of the present application, whether the first heat pump operating parameter meets the defrost mode start-up conditions is determined to avoid not switching the four-way valve when the frost layer is too thick or unevenly distributed, and defrosting is performed by starting the auxiliary heating device; when the first heat pump operating parameter meets the defrost mode start-up conditions, the current high and low pressure difference of the compressor is controlled by frequency reduction to be within the allowable switching pressure difference range, thereby ensuring the pressure stability of the refrigerant during the switching process, avoiding stress increase due to sudden pressure change, and determining the target enthalpy increase valve control strategy through the current ambient temperature and the current water outlet temperature to achieve joint control of the enthalpy increase valve and the four-way valve under extreme working conditions, avoiding reducing the impact of the refrigerant switching on the four-way valve, and realizing precise control of the four-way valve under the defrost operation of the low-temperature heat pump, reducing the probability of stress concentration and liquid hammer, extending the service life of the four-way valve, and improving the stability of the low-temperature heat pump.

[0103] above Figure 3 and Figure 4 The four-way valve linkage control device in the embodiment of the present application is described in detail from the perspective of modular functional entities, and the four-way valve linkage control device in the embodiment of the present application is described in detail from the perspective of hardware processing.

[0104] See also Figure 5 As shown, the four-way valve linkage control device includes a processor 500 and a memory 501. The memory 501 stores machine executable instructions that can be executed by the processor 500. The processor 500 executes the machine executable instructions to implement the above-mentioned four-way valve linkage control method.

[0105] Furthermore, Figure 5The four-way valve linkage control device shown further includes a bus 502 and a communication interface 503 , and the processor 500 , the communication interface 503 and the memory 501 are connected via the bus 502 .

[0106] Among them, the memory 501 may include a high-speed random access memory (RAM), and may also include a non-volatile memory (non-volatile memory), for example, at least one disk storage. The communication connection between the system network element and at least one other network element is realized through at least one communication interface 503 (which can be wired or wireless), and the Internet, wide area network, local area network, metropolitan area network, etc. can be used. The bus 502 can be an ISA bus, a PCI bus, or an EISA bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, Figure 5 Only one bidirectional arrow is used in the diagram, but this does not mean that there is only one bus or one type of bus.

[0107] The processor 500 may be an integrated circuit chip with signal processing capabilities. During implementation, each step of the above method can be completed by hardware integrated logic circuits or software instructions in the processor 500. The processor 500 may be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it may also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present disclosure. The general-purpose processor may be a microprocessor or any conventional processor. The steps of the method disclosed in conjunction with the embodiments of the present disclosure may be directly implemented and executed by a hardware decoding processor, or by a combination of hardware and software modules in the decoding processor. The software module may be located in a storage medium mature in the art, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, registers, etc. The storage medium is located in the memory 501 , and the processor 500 reads the information in the memory 501 and completes the method steps of the aforementioned embodiment in combination with its hardware.

[0108] The application further provides a computer readable storage medium, which can be a nonvolatile computer readable storage medium or a volatile computer readable storage medium, and the computer readable storage medium stores instructions, which, when executed on a computer, cause the computer to perform the steps of the four-way valve linkage control method.

[0109] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the above-described systems, devices and units can refer to the corresponding processes in the foregoing method embodiments, which will not be described here.

[0110] If the integrated units are implemented in the form of software function units and sold or used as independent products, the integrated units can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application or the entire or part of the technical solutions that essentially contribute to the prior art can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a plurality of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the embodiments of the method of the present application. The foregoing storage medium includes a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and various program code storage media.

[0111] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacements for some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A four-way valve linkage control method, characterized in that: Applied to a low-temperature heat pump, the four-way valve linkage control method includes: In response to a defrost mode start instruction, determining whether a first heat pump operating parameter currently corresponding to the low-temperature heat pump satisfies a defrost mode start condition; If so, the compressor is controlled to reduce frequency until the current high and low pressure differential is within the preset switching pressure differential range, and the target enthalpy increasing valve control strategy is determined according to the current ambient temperature, the current outlet water temperature, and a plurality of preset initial temperature enthalpy increasing valve control intervals; otherwise, the four-way valve is controlled to maintain the first target state, wherein the plurality of initial temperature enthalpy increasing valve control intervals include at least one enthalpy increasing closing interval and at least one enthalpy increasing maintaining interval; performing linkage control on the enthalpy increasing valve and the four-way valve based on the target enthalpy increasing valve control strategy, and switching the four-way valve to a second target state; When the second heat pump operating parameter currently corresponding to the low-temperature heat pump meets the defrost mode exit condition, controlling the four-way valve to switch to the first target state; The step of determining a target enthalpy increasing valve control strategy based on the current ambient temperature, the current outlet water temperature, and a plurality of preset initial temperature enthalpy increasing valve control intervals includes: If the current ambient temperature and the current outlet water temperature are in any enthalpy increase maintenance interval, determining the target enthalpy increase valve control strategy to maintain the current opening adjustment; If the current ambient temperature and the current outlet water temperature are in any enthalpy increase closing interval, the target enthalpy increase valve control strategy is determined to close the enthalpy increase valve according to the target early closing period.

2. The four-way valve linkage control method according to claim 1, characterized in that: If so, the compressor is controlled to reduce frequency until the current high and low pressure difference is within the preset switching pressure difference range, including: When the operating parameters of the first heat pump meet the start-up conditions of the defrost mode, the compressor is controlled to reduce the frequency until the current high and low pressure difference is within the preset switching pressure difference range, and the timing is started when the compressor frequency is reduced to the target frequency. The target frequency is the operating frequency of the compressor when the current high and low pressure difference is within the preset switching pressure difference range.

3. The four-way valve linkage control method according to claim 2, characterized in that: The step of controlling the enthalpy increasing valve and the four-way valve in a linkage manner based on the target enthalpy increasing valve control strategy, wherein the four-way valve is switched to a second target state, includes: If the target enthalpy-increasing valve control strategy includes a target early closing period, the enthalpy-increasing valve is controlled to close early according to the operating time of the compressor at the target frequency and the target early closing period, and the four-way valve is controlled to switch to the second target state when the operating time reaches a preset switching period; If the target enthalpy increasing valve control strategy is to maintain the current opening adjustment, the enthalpy increasing valve is controlled to maintain the current opening, and when the operating time reaches a preset switching cycle, the four-way valve is controlled to switch to the second target state.

4. The four-way valve linkage control method according to claim 1, characterized in that: The step of determining, in response to the defrost mode start instruction, whether the first heat pump operating parameter currently corresponding to the low-temperature heat pump satisfies the defrost mode start condition comprises: In response to a defrost mode start instruction, obtaining first heat pump operating parameters currently corresponding to the low-temperature heat pump, the first heat pump operating parameters including a first heat exchanger temperature, a first low-pressure value, and a first fan current value; If the first heat exchanger temperature is greater than the preset first temperature threshold, the first low-pressure value is greater than the preset first low-pressure threshold, and the first fan current value is less than the preset first current threshold, it is determined that the defrost mode start-up conditions are met; otherwise, it is determined that the defrost mode start-up conditions are not met.

5. The four-way valve linkage control method according to claim 1, characterized in that: When the second heat pump operating parameter currently corresponding to the low-temperature heat pump satisfies the defrost mode exit condition, controlling the four-way valve to switch to the first target state includes: Acquire a second heat pump operating parameter currently corresponding to the low-temperature heat pump, where the second heat pump operating parameter includes at least one parameter of a second heat exchanger temperature, a second low-pressure value, and a second fan current value; If the second heat exchanger temperature is greater than the preset second temperature threshold, and / or the second low pressure value is greater than the preset second low pressure threshold, and / or the second fan current value is less than the preset second current threshold, the four-way valve is controlled to switch to the first target state.

6. The four-way valve linkage control method according to any one of claims 1 to 5, characterized in that: If so, the compressor is controlled to reduce frequency until the current high and low pressure difference is within the preset switching pressure difference range, and the target enthalpy increasing valve control strategy is determined according to the current ambient temperature, the current outlet water temperature and the preset multiple initial temperature enthalpy increasing valve control intervals; otherwise, after the four-way valve is controlled to maintain the first target state, the method further includes: If the first heat pump operating parameter does not meet the defrost mode start condition, the four-way valve is controlled to maintain the first target state and the auxiliary defrost mode is started.

7. The four-way valve linkage control method according to claim 6, characterized in that: If the first heat pump operating parameter does not meet the defrost mode start condition, controlling the four-way valve to maintain the first target state and starting the auxiliary defrost mode includes: If the operating parameters of the first heat pump do not meet the defrost mode start conditions, the auxiliary heating device is controlled to perform defrost and the timing is started; When the auxiliary heating time reaches a preset auxiliary heating time, and / or the third heat pump operating parameter meets the defrost mode start condition, the auxiliary heating device is turned off.

8. A four-way valve linkage control device, characterized in that: Applied to low-temperature heat pumps, the four-way valve linkage control device includes: a judgment module, configured to judge, in response to a defrost mode start instruction, whether a first heat pump operating parameter currently corresponding to the low-temperature heat pump satisfies a defrost mode start condition; a processing module configured to, if so, control the compressor to reduce frequency until the current high and low pressure differential is within a preset switching pressure differential range, and determine a target enthalpy increasing valve control strategy based on the current ambient temperature, the current outlet water temperature, and a plurality of preset initial temperature enthalpy increasing valve control intervals; otherwise, control the four-way valve to maintain a first target state, wherein the plurality of initial temperature enthalpy increasing valve control intervals include at least one enthalpy increasing closing interval and at least one enthalpy increasing maintaining interval; a linkage control module, configured to perform linkage control on the enthalpy increasing valve and the four-way valve based on the target enthalpy increasing valve control strategy, so that the four-way valve switches to a second target state; an exit control module, configured to control the four-way valve to switch to a first target state when the second heat pump operating parameter currently corresponding to the low-temperature heat pump satisfies a defrost mode exit condition; The processing module is specifically configured to determine the target enthalpy increase valve control strategy to maintain the current opening adjustment if the current ambient temperature and the current outlet water temperature are in any enthalpy increase maintenance interval; If the current ambient temperature and the current outlet water temperature are in any enthalpy increase closing interval, the target enthalpy increase valve control strategy is determined to close the enthalpy increase valve according to the target early closing period.

9. A four-way valve linkage control device, characterized in that: The four-way valve linkage control device includes: a memory and at least one processor, wherein the memory stores control instructions; The at least one processor calls the control instruction in the memory to enable the four-way valve linkage control device to execute the four-way valve linkage control method according to any one of claims 1 to 7.

10. A computer-readable storage medium having control instructions stored thereon, characterized in that: When the control instruction is read and executed, the four-way valve linkage control method according to any one of claims 1 to 7 is executed.

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