Control method and device of electronic expansion valve, readable storage medium and heat pump system

Abstract

The present application relates to a kind of electronic expansion valve control method, device, readable storage medium and heat pump system.Electronic expansion valve control method, comprising the following steps: starting heat pump unit, the opening degree of electronic expansion valve is adjusted to initial step P0, and the return air temperature T1 of evaporator is detected;Start compressor, and in the 0-1 min time period of compressor opening, electronic expansion valve automatically adjusts step P1;The calculation formula of step P1 is P1=K1*T1+P0;Wherein, K1 is coefficient;After 1 min of compressor opening, electronic expansion valve automatically adjusts step P2 according to superheat degree.The present application ingeniously solves the situation that heat pump system high-temperature start is prone to failure by using return air temperature and adjusting electronic expansion valve initial opening degree in time, so that electronic expansion valve can accurately control the flow of refrigerant, to realize accurate temperature control.Compared with traditional single initial opening degree, the mode of using return air temperature can more flexibly adapt to various scenes, and adapt to the needs of cold and hot start to system.

Description

Technical Field

[0001] This invention relates to the field of heat pump system technology, and in particular to a control method, device, readable storage medium, and heat pump system for an electronic expansion valve. Background Technology

[0002] The opening degree of the electronic expansion valve is a measure of the refrigerant flow through it, usually expressed in "steps." A larger opening degree means a greater amount of refrigerant passes through the valve. In existing heat pump systems, the electronic expansion valve is adjusted after the system is started. By default, the valve opens to the initial opening degree first, and then the compressor is started to adjust according to the superheat level.

[0003] Existing heat pump systems use the same initial opening degree for both cold and hot starts, but the amount of refrigerant required for the two starts is different. Fixing the initial opening degree and relying solely on superheat adjustment obviously cannot meet the daily start-up requirements.

[0004] When a heat pump system is shut down normally during operation, if it needs to be restarted within a short period (half an hour to one hour), the compressor is prone to triggering a high-pressure alarm, preventing the equipment from starting normally. This may be because the oven temperature in the heat pump system is too high, requiring a large amount of refrigerant during hot start-up, and the electronic expansion valve opening may not meet the demand, leading to potential malfunctions. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a control method for an electronic expansion valve, which uses the return air temperature to adjust the initial opening degree of the electronic expansion valve in a timely manner, thereby avoiding the situation where existing heat pump systems are prone to malfunctions during hot start-up, and is applicable to both cold and hot start-up of heat pump systems.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for controlling an electronic expansion valve includes the following steps:

[0008] Turn on the heat pump unit, adjust the opening of the electronic expansion valve to the initial step number P0, and detect the return air temperature T1 of the evaporator;

[0009] The compressor is turned on, and during the 0-1 minute period after the compressor is turned on, the electronic expansion valve automatically adjusts the number of steps P1; the formula for calculating the number of steps P1 is P1=K1*T1+P0; where K1 is a coefficient;

[0010] One minute after the compressor starts, the electronic expansion valve automatically adjusts the superheat step P2.

[0011] The electronic expansion valve control method described in this invention adjusts the initial opening degree of the electronic expansion valve in a timely manner by detecting the return air temperature T1 of the evaporator of the heat pump system, so that it can take into account both the low opening degree required for cold start and the high opening degree required for hot start, avoiding the use of the same initial opening degree for both cold and hot start.

[0012] In addition, the initial opening degree is adjusted based on the return air temperature T1 within 1 minute. The duration of this adjustment is relatively reasonable. If the time is too short or too long, it will affect the stability of the heat pump system. Then, after 1 minute, the system automatically switches to adjusting the opening degree based on the superheat. The combination of these two methods allows the electronic expansion valve to precisely control the refrigerant flow, thereby achieving precise temperature control.

[0013] As a preferred method, the formula for calculating the number of steps P1 is P1 = 8 * T1 + 80. Through extensive experiments, this invention has shown that adjusting the opening using the formula P1 = 8 * T1 + 80 yields the best results for different return air temperatures.

[0014] As a preferred method, the formula for calculating P2 is: P2 = P1 + ΔP, where ΔP is the change in the opening degree of the electronic expansion valve.

[0015] As a preferred method, the formula for calculating ΔP is: ΔP = K P *(SH 平均 -TSH); where K P SH is a coefficient. 平均 The actual average superheat during the test period is represented by TSH, which represents the target superheat.

[0016] As a preferred method:

[0017] When SH 平均 When K ≤ -1 P =3;

[0018] When -1 <SH 平均 When K ≤ 0 P =2;

[0019] When SH 平均 When K > 0, P =1.

[0020] As a preferred method: SH 平均 This represents the average actual superheat over 30 seconds, with samples taken every 5 seconds.

[0021] Furthermore, the formula for calculating the actual superheat SH in each sample is: SH = T S -T C T S T represents the compressor return gas temperature. C This refers to the coil temperature.

[0022] The present invention also provides a control device for an electronic expansion valve, comprising:

[0023] The acquisition module is used to acquire the initial step number P0 of the electronic expansion valve and detect the return air temperature T1 of the evaporator;

[0024] The processing module is used to automatically calculate and control the number of steps P1 of the electronic expansion valve adjustment based on the detected evaporator return air temperature T1 during the 0-1 minute period after the compressor starts, according to the formula P1=K1*T1+P0; it is also used to automatically switch to the number of steps P2 of the electronic expansion valve adjustment based on superheat control after the compressor starts for 1 minute.

[0025] The present invention also provides a readable storage medium storing a computer program, which is read and executed by a processing module to implement the control method of the electronic expansion valve as described above.

[0026] The present invention also provides a heat pump system, including any of the above-described readable storage media and any of the above-described electronic expansion valve control devices; when the processing module reads and runs the computer program, it implements any of the above-described electronic expansion valve control methods.

[0027] The beneficial effects of this invention are as follows:

[0028] The present invention relates to an electronic expansion valve control method, apparatus, readable storage medium, and heat pump system. By utilizing return air temperature to adjust the initial opening degree of the electronic expansion valve in a timely manner, it cleverly solves the problem of frequent malfunctions during high-temperature startup of heat pump systems. This allows the electronic expansion valve to precisely control the refrigerant flow, thereby achieving accurate temperature control. Compared with the traditional single initial opening degree, the method of using return air temperature can more flexibly adapt to various scenarios and adaptively meet the system's requirements for cold and hot startups.

[0029] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

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

[0031] Figure 2 This is a schematic diagram of a control device for an electronic expansion valve according to the present invention;

[0032] The components are as follows: 1. First heat pump unit; 11. Heat pump unit (specifically, sludge drying box); 12. Evaporator; 13. Condenser; 2. Second heat pump unit; 21. Compressor; 22. Plate heat exchanger; 23. Electronic expansion valve; 3. Control device for electronic expansion valve; 31. Acquisition module; 311. Return air temperature sensor; 32. Processing module. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0034] It should be understood that the described embodiments are only some embodiments of the embodiments of this application, and not all embodiments.

[0035] Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the embodiments in this application.

[0036] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0037] Furthermore, in the description of this application, unless otherwise stated, "multiple" means two or more. "And / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A alone, A and B simultaneously, or B alone. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0038] It should be understood that the embodiments of this application are not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from their scope. The scope of the embodiments of this application is limited only by the appended claims.

[0039] Please see Figure 1 This invention provides a heat pump system, specifically a dryer heat pump system, including a first heat pump unit 1 and a second heat pump unit 2, an electronic expansion valve control device 3, and a readable storage medium (not shown).

[0040] The first heat pump unit 1 has an airflow structure that connects the heat pump unit 11, evaporator 12, and condenser 13 through pipelines to form a loop. In this embodiment, the heat pump unit 11 is a sludge drying box. The second heat pump unit 2 has a refrigerant flow structure that connects the compressor 21, plate heat exchanger 22, condenser 13, electronic expansion valve 23, and evaporator 12 through pipelines to form a loop. The above description of the first heat pump unit 1 and the second heat pump unit 2 only lists some of the structures and is not intended to limit the scope of the heat pump system of the present invention. Those skilled in the art will know from their knowledge that the first heat pump unit 1 and the second heat pump unit 2 may also include other devices, which will not be described in detail here.

[0041] The heat pump unit 11 dries materials such as sludge, and the air after drying returns to the evaporator 12 for heat exchange with refrigerant. This invention has found that when the heat pump system is normally shut down during operation, if it needs to be restarted within a short time (half an hour to one hour), the compressor 21 of the heat pump system is prone to high-pressure alarms, preventing the equipment from starting normally. This is because the temperature of the heat pump unit 11 (i.e., the sludge drying chamber) is too high, and the evaporator 12 requires a large amount of refrigerant during hot start-up. Consequently, the compressor 21 requires a large amount of refrigerant, and the existing control method for adjusting the opening of the electronic expansion valve 23 cannot meet the demand, leading to frequent malfunctions.

[0042] Therefore, this invention designs and develops a control method, device, and readable storage medium for an electronic expansion valve. The control method for the electronic expansion valve of this invention will be described below based on the exemplified heat pump system. It should be understood that the first heat pump unit 1 and the second heat pump unit 2 of the above heat pump system are not intended to limit this invention. Those skilled in the art can apply the control method, device, and readable storage medium of this invention to other heat pump systems, which also falls within the scope of this invention.

[0043] The invention also provides a control method for an electronic expansion valve, comprising the following steps:

[0044] Turn on the heat pump unit 11, adjust the opening of the electronic expansion valve 23 to the initial step number P0, and detect the return air temperature T1 of the evaporator 12;

[0045] The compressor 21 is turned on, and during the 0-1 minute period after the compressor is turned on, the electronic expansion valve automatically adjusts the number of steps P1; the formula for calculating the number of steps P1 is P1=K1*T1+P0; where K1 is a coefficient;

[0046] One minute after the compressor starts, the electronic expansion valve automatically adjusts the superheat step P2.

[0047] The return air is the substance closest to the evaporator 12 in the entire heat pump unit 11. The return air temperature T1 can provide feedback on the temperature of the air returning to the evaporator 12 after the heat pump unit 11 has dried the material. By detecting the return air temperature T1, the initial opening degree of the electronic expansion valve 23 is adjusted to ensure that the opening degree of the electronic expansion valve 23 meets the requirements, so that the heat pump system can meet the start-up requirements of different scenarios. In some embodiments, the return air temperature T1 can be detected on the pipe between the heat pump unit 11 and the evaporator 12.

[0048] As a preferred implementation, the formula for calculating the number of steps P1 is P1 = 8 * T1 + 80. Adjusting the opening according to the formula P1 = 8 * T1 + 80 can meet the required number of steps for different return air temperatures, resulting in good adjustment performance.

[0049] As a preferred implementation, after adjusting the opening degree according to P1 = 8*T1 + 80 for 1 minute, the heat pump system automatically switches to automatic adjustment step P2 according to the superheat.

[0050] During the conversion to superheat adjustment step P2, the heat pump system calculates the actual opening of the electronic expansion valve by detecting the compressor return gas temperature and coil temperature, and then controls the electronic expansion valve.

[0051] The specific control methods are as follows:

[0052] The formula for calculating P2 is: P2 = P1 + ΔP, where ΔP is the change in the opening of the electronic expansion valve.

[0053] The formula for calculating ΔP is: ΔP = K P *(SH 平均 -TSH); where K P SH is a coefficient. 平均 SH represents the actual average superheat during the test period, and TSH represents the target superheat. 平均 This represents the average actual superheat over 30 seconds, with samples taken every 5 seconds. The formula for calculating the actual superheat SH in each sample is: SH = T S -T C T S T represents the compressor return gas temperature. C This refers to the coil temperature.

[0054] Therefore, the heat pump system controls the electronic expansion valve 23 every 30 seconds.

[0055] In this embodiment: when SH 平均 When K ≤ -1 P =3; when -1 <SH 平均 When K ≤ 0 P =2; when SH 平均 When K > 0, P =1.

[0056] In this embodiment, after adjusting the opening degree by P1 = 8*T1 + 80 for 1 minute, the heat pump system automatically switches to automatic adjustment based on the superheat level. The method of adjusting based on superheat level can also refer to existing methods and techniques, which will not be elaborated here.

[0057] As those skilled in the art will know, the coil temperature is the corresponding evaporation temperature calculated from the compressor's low-pressure reading measured by the pressure sensor. Therefore, in this embodiment of the invention, the compressor pressure value measured by the pressure sensor can also be used to calculate and adjust the superheat. When the pressure sensor fails, the coil temperature detected by the coil temperature sensor is used instead. Therefore, in this embodiment of the invention, superheat adjustment calculation is performed in two ways, which can increase the stability of superheat adjustment. In this embodiment, when both the pressure sensor and the coil temperature sensor fail simultaneously, or when the compressor return gas temperature detection fails, the electronic expansion valve returns to its initial opening.

[0058] As a specific approach, the overall process of controlling the electronic expansion valve when starting a heat pump system can be summarized as follows:

[0059] After the heat pump system is powered on, the electronic expansion valve 23 first resets and closes at 550N (the operating range is 0-480N). Then, the opening of the electronic expansion valve 23 jumps to the initial opening. The heat pump unit 11 is started, the compressor 21 is started, and the electronic expansion valve 23 is adjusted according to P1 = 8 * T1 + 80 steps. After maintaining this for 1 minute, it switches to automatic adjustment based on superheat.

[0060] To achieve the above method, embodiments of the present invention also provide a control device for an electronic expansion valve, comprising:

[0061] The acquisition module 31 is used to acquire the initial step number P0 of the electronic expansion valve and detect the return air temperature T1 of the evaporator 12;

[0062] The processing module 32 is used to automatically calculate and control the number of steps P1 of the electronic expansion valve 23 according to the formula P1=K1*T1+P0 (specifically P1=8*T1+80) based on the detected return air temperature T1 of the evaporator 12 during the 0-1 minute time period after the compressor is turned on; it is also used to automatically switch to the step number P2 of the electronic expansion valve 23 controlled by superheat control after the compressor is turned on for 1 minute.

[0063] In this embodiment, the acquisition module 31 includes a return air temperature sensor 311 disposed on the pipe between the heat pump unit 11 and the evaporator 12, preferably disposed near the evaporator 12, so as to accurately feed back the return air temperature T1.

[0064] This invention also provides a readable storage medium storing a computer program. When the computer program is read and executed by a processing module, it implements the electronic expansion valve control method described in this invention.

[0065] The electronic expansion valve control method described in this invention adjusts the initial opening degree of the electronic expansion valve in a timely manner by detecting the return air temperature of the evaporator in the heat pump system. This ensures that the valve can accommodate both the low opening value required for cold starts and the high opening value required for hot starts, avoiding the use of the same initial opening degree for both cold and hot starts. The initial opening degree is adjusted based on the return air temperature T1 over a 1-minute period, which is a relatively reasonable duration; too short or too long a period would affect the stability of the heat pump system. After another 1-minute period, the valve automatically switches to adjusting the opening degree based on superheat. This combination allows the electronic expansion valve to precisely control the refrigerant flow, thereby achieving precise temperature control.

[0066] The present invention relates to an electronic expansion valve control method, apparatus, readable storage medium, and heat pump system. By utilizing return air temperature to adjust the initial opening degree of the electronic expansion valve in a timely manner, it cleverly solves the problem of frequent malfunctions during high-temperature startup of heat pump systems. This allows the electronic expansion valve to precisely control the refrigerant flow, thereby achieving accurate temperature control. Compared with the traditional single initial opening degree, the method of using return air temperature can more flexibly adapt to various scenarios and adaptively meet the system's requirements for cold and hot startups.

[0067] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and the present invention also intends to include these modifications and variations.

Claims

1. A control method for an electronic expansion valve, characterized in that: The electronic expansion valve is an electronic expansion valve in a heat pump system. The heat pump system includes a first heat pump unit and a second heat pump unit. The first heat pump unit has an airflow structure that connects the heat pump unit, evaporator, and condenser through pipelines to form a loop. The second heat pump unit has a refrigerant flow structure that connects the compressor, plate heat exchanger, condenser, electronic expansion valve, and evaporator through pipelines to form a loop. The control method for the electronic expansion valve includes the following steps: Turn on the heat pump unit, adjust the opening of the electronic expansion valve to the initial step number P0, and detect the return air temperature T1 of the evaporator; The compressor is turned on, and during the 0-1 minute period after the compressor starts, the electronic expansion valve automatically adjusts by a step number P1; the formula for calculating the step number P1 is P1=K1. T1+P0; where K1 is the coefficient; After the compressor is turned on for 1 minute, the electronic expansion valve automatically switches to adjusting according to the superheat step P2.

2. The control method for the electronic expansion valve according to claim 1, characterized in that: The formula for calculating the number of steps P1 is P1=8. T1+80.

3. The control method for the electronic expansion valve according to claim 1, characterized in that: The formula for calculating P2 is P2 = P1 + ΔP, where ΔP is the change in the opening degree of the electronic expansion valve.

4. The control method for the electronic expansion valve according to claim 3, characterized in that: The formula for calculating ΔP is ΔP=K P (SH) 平均 -TSH); where K P SH is a coefficient. 平均 The actual average superheat during the test period is represented by TSH, which represents the target superheat.

5. The control method for the electronic expansion valve according to claim 4, characterized in that: When SH 平均 When K ≤ -1 P =3; When -1 <SH 平均 When K ≤ 0 P =2; When SH 平均 When K > 0, P =1.

6. The control method for the electronic expansion valve according to claim 4, characterized in that: SH 平均 This represents the average actual superheat over 30 seconds, with samples taken every 5 seconds.

7. The control method for the electronic expansion valve according to claim 4, characterized in that: The formula for calculating the actual superheat SH in each sample is: SH = T S -T C T S T represents the compressor return gas temperature. C This refers to the coil temperature.

8. A control device for an electronic expansion valve, characterized in that: The control device for the electronic expansion valve is used to implement the control method for the electronic expansion valve as described in any one of claims 1-7; the control device for the electronic expansion valve includes: The acquisition module is used to acquire the initial step number P0 of the electronic expansion valve and detect the return air temperature T1 of the evaporator; The processing module is used to, during the 0-1 minute period after the compressor starts, calculate the return air temperature T1 of the evaporator according to the formula P1=K1. T1+P0 automatically calculates and controls the step number P1 of adjusting the electronic expansion valve; it is also used to automatically switch to adjusting the electronic expansion valve according to superheat control P2 1 minute after the compressor is turned on.

9. A readable storage medium storing a computer program that is read and executed by a processing module to implement the control method of the electronic expansion valve as described in any one of claims 1-7.

10. A heat pump system, characterized in that: The system includes a first heat pump unit and a second heat pump unit; the first heat pump unit has an airflow structure that connects the heat pump unit, evaporator, and condenser through pipelines to form a loop; the second heat pump unit has a refrigerant flow structure that connects the compressor, plate heat exchanger, condenser, electronic expansion valve, and evaporator through pipelines to form a loop; the heat pump system further includes a readable storage medium as described in claim 9 and a control device for the electronic expansion valve as described in claim 8; when the processing module reads and runs the computer program, it implements the control method for the electronic expansion valve as described in any one of claims 1-7.

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