An electronic expansion valve adjustment method based on the exhaust temperature limit

Abstract

The present invention relates to a method for regulating an electronic expansion valve based on the exhaust temperature limit; the method includes the following steps: the unit is started and operated, and a target exhaust temperature Pdo is set n ; the current maximum exhaust temperature Pdmax is obtained n and the current minimum exhaust temperature Pdmin n . By comparing the current maximum exhaust temperature Pdmax n and the current minimum exhaust temperature Pdmin n with the target exhaust temperature Pdo n respectively, the opening limit control of the electronic expansion valve is adjusted; the current maximum opening EXVmax of the electronic expansion valve is obtained n and the current minimum opening EXVmin of the electronic expansion valve n . When the following conditions are simultaneously satisfied, it is determined not to enter the opening limit control of the electronic expansion valve: Condition 1: EXVmax n‑2 - EXVmin n‑2 ≥ EXVmax n‑1 - EXVmin n‑1 ≥ EXVmax n - EXVmin n ; Condition 2: EXVmax n - EXVmin n ≤ a, where a is a constant and can be adjusted according to the requirements of different systems; to achieve precise regulation of the electronic expansion valve.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic expansion valves, and particularly to an adjustment method for an electronic expansion valve based on the exhaust temperature limit. Background Art

[0002] At present, in the field of air conditioners, the common control methods for electronic expansion valves are two types: target exhaust temperature and the combination of target exhaust temperature and target suction superheat:

[0003] The target exhaust temperature control determines the target exhaust temperature through a calculation formula. The electronic expansion valve determines the opening change amount of the electronic expansion valve based on the comparison between the actual exhaust temperature and the target exhaust temperature, usually using a calculation formula or a determined opening change amount table, so that the actual exhaust temperature reaches the target exhaust temperature.

[0004] The control method combining target exhaust temperature and target suction superheat compares the actual suction superheat with the determined target suction superheat to adjust the opening of the electronic expansion valve. When the actual suction superheat reaches the target suction superheat, it is then judged whether the actual exhaust temperature meets the target exhaust temperature. If it meets, the target suction superheat is not adjusted. If it does not meet, the target suction superheat is adjusted.

[0005] For these two control methods, due to the problems of inappropriate adjustment cycle, adjustment amount or adjustment range of the electronic expansion valve, the actual exhaust temperature will show periodic fluctuations around the target exhaust temperature, especially obvious during low ambient temperature heating. Moreover, considering reliability, it is very difficult to make the adjustment cycle and adjustment amount meet all working conditions. Therefore, the unit cannot be stable for a long time, there will be stage liquid return of the unit, and even the capacity fluctuation is very large, seriously affecting the product stability and reliability. Summary of the Invention

[0006] The purpose of the present invention is to provide an adjustment method for an electronic expansion valve based on the exhaust temperature limit to achieve precise control of the electronic expansion valve.

[0007] To achieve the above object, the main technical solution of the present invention is an adjustment method for an electronic expansion valve based on the exhaust temperature limit, which is characterized by including the following steps:

[0008] The unit starts to operate, and a target exhaust temperature Pdo is set n ;

[0009] Obtain the current maximum exhaust temperature Pdmax n and the current minimum exhaust temperature Pdmin n , and respectively compare the current maximum exhaust temperature Pdmax n and the current minimum exhaust temperature Pdmin n with the target exhaust temperature Pdon Compare to adjust the opening limit control of the electronic expansion valve;

[0010] Obtain the maximum opening EXVmax of the current electronic expansion valve n and the minimum opening EXVmin of the current electronic expansion valve n , and determine not to enter the opening limit control of the electronic expansion valve while satisfying the following conditions:

[0011] Condition 1: EXVmax n-2 -EXVmin n-2 ≥EXVmax n-1 -EXVmin n-1 ≥EXVmax n -EXVmin n ;

[0012] Condition 2: EXVmax n -EXVmin n ≤a.

[0013] In some instances, when the unit receives the first startup command, the electronic expansion valve resets and determines the initial opening of the electronic expansion valve based on the ambient temperature value. After the compressor starts, the electronic expansion valve maintains the initial opening for 3 minutes, and automatically adjusts the opening of the electronic expansion valve according to the exhaust target value after operation, and continuously detects and records the maximum opening EXVmax of the current electronic expansion valve n and the minimum opening EXVmin of the current electronic expansion valve n .

[0014] In some instances, each time entering the opening limit control of the electronic expansion valve, obtain the previous opening limit of the electronic expansion valve; adjust the current opening limit control of the electronic expansion valve based on the previous opening limit of the electronic expansion valve and the limit adjustment amount ΔEXV of the electronic expansion valve obtained through the calculation formula.

[0015] In some instances, determine the first opening limit of the electronic expansion valve: Take the maximum opening EXVmax of the current electronic expansion valve detected at the first startup n as the upper limit value EXVlimitmax of the first electronic expansion valve n , and take the minimum opening EXVmin of the current electronic expansion valve detected at the first startup n as the lower limit value EXVlimitmin of the first electronic expansion valve n , and the upper limit value EXVlimitmax of the first electronic expansion valve n and the lower limit value EXVlimitmin of the first electronic expansion valve n serve as the upper and lower limit values EXVlimitmax of the next basic electronic expansion valve n-1and EXVlimitmin n-1 。

[0016] In some instances, the calculation formula for the limit adjustment amount of the electronic expansion valve is

[0017]

[0018] In some instances, the specific control of the opening limit value of the electronic expansion valve includes the following control steps:

[0019] If Pdmin n ≥Pdo n , then EXVlimitmax n =EXVlimitmax n-1 +ΔEXV, EXVlimitmin n =EXVlimitmin n-1 +ΔEXV;

[0020] If Pdmax n >Pdo n >Pdmin n , then for the control under this condition, a constant value is introduced, and based on the upper and lower limit values of the previous electronic expansion valve, adjustment is made through the ratio of ΔEXV to the constant value;

[0021] If Pdmax n ≤Pdo n , then EXVlimitmax n =EXVlimitmax n-1 -ΔEXV, EXVlimitmin n =EXVlimitmin n-1 -ΔEXV.

[0022] In some instances, if Pdmax n >Pdo n >Pdmin n and Pdmax n -Pdo n >Pdo n -Pdmin n , then EXVlimitmin n =EXVlimitmin n-1 +(ΔEXV / b);

[0023] If Pdmax n >Pdo n >Pdmin n and Pdmax n -Pdo n =Pdon -Pdmin n , then EXVlimitmax n = EXVlimitmax n-1 × c, EXVlimitmin n = EXVlimitmin n-1 × c;

[0024] If Pdmax n > Pdo n > Pdmin n and Pdmax n - Pdo n < Pdo n - Pdmin n , then EXVlimitmax n = EXVlimitmax n-1 -(ΔEXV / b);

[0025] where b is a constant value determined according to different unit configurations; c is a variable, and the range of c is from 10% to 100%.

[0026] In some instances, after each entry into the opening limit control of the electronic expansion valve, the maximum exhaust gas temperature obtained last time is denoted as Pdmax n-1 , the minimum exhaust gas temperature obtained last time is denoted as Pdmin n-1 , after entering the control, clear Pdmax n-1 and Pdmin n-1 , and re - obtain the current maximum exhaust gas temperature Pdmax n and the current minimum exhaust gas temperature Pdmin n , and perform cyclic operations.

[0027] Due to the adoption of the above - mentioned technical solutions, the present invention achieves the following effects:

[0028] 1. The adjustment range of the electronic expansion valve changes in real time; 2. The targeted adjustment of the adjustment range of the electronic expansion valve enables the actual exhaust gas temperature to reach the target exhaust gas temperature more accurately and quickly. Brief Description of the Drawings

[0029] Figure 1 is the fluctuation curve graph of the current exhaust gas temperature and the target exhaust gas temperature of Control One,

[0030] Figure 2 is the fluctuation curve graph of the current exhaust gas temperature and the target exhaust gas temperature of Control Two.1,

[0031] Figure 3 is the fluctuation curve graph of the current exhaust gas temperature and the target exhaust gas temperature of Control Two.2,

[0032] Figure 4 is a fluctuation curve graph of the current exhaust gas temperature and the target exhaust gas temperature of Control II.3

[0033] Figure 5 is a fluctuation curve graph of the current exhaust gas temperature and the target exhaust gas temperature of Control III Specific Embodiments

[0034] The following description is used to disclose the present invention so that those skilled in the art can implement the present invention. The preferred embodiments in the following description are only examples, and those skilled in the art can think of other obvious variations. The basic principles defined in the following description of the present invention can be applied to other implementation schemes, variation schemes, improvement schemes, equivalent schemes, and other technical schemes without departing from the spirit and scope of the present invention

[0035] Those skilled in the art should understand that in the disclosure of the present invention, the orientation or positional relationships indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientation or positional relationships shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting the present invention

[0036] It can be understood that the term "one" should be understood as "at least one" or "one or more". That is, in one embodiment, the number of one element can be one, and in other embodiments, the number of this element can be multiple. The term "one" should not be construed as limiting the quantity

[0037] Embodiment 1

[0038] Referring to Figures 1 to 5 shown in the accompanying drawings of the specification of the present invention, a method for adjusting an electronic expansion valve based on an exhaust gas temperature limit according to a preferred embodiment of the present invention includes the following steps: The unit is started and operated, and a target exhaust gas temperature Pdo is set n ; Obtain the maximum value Pdmax of the current exhaust gas temperature n and the minimum value Pdmin of the current exhaust gas temperature n , and compare the maximum value Pdmax of the current exhaust gas temperature n and the minimum value Pdmin of the current exhaust gas temperature n with the target exhaust gas temperature Pdo respectively n to adjust the opening limit control of the electronic expansion valve; Obtain the maximum opening EXVmax of the current electronic expansion valve n and the minimum opening EXVmin of the current electronic expansion valven , and it is determined not to enter the opening limit control of the electronic expansion valve while meeting the following conditions: Among them, Condition 1: EXVmax n-2 -EXVmin n-2 ≥EXVmax n-1 -EXVmin n-1 ≥EXVmax n -EXVmin n ; Condition 2: EXVmax n -EXVmin n ≤a (a is a constant and can be adjusted according to the requirements of different system manufacturers). The main innovation of this technical solution is that by detecting the relationship between the change in the opening of the electronic expansion valve and the fluctuation range of the exhaust temperature, as well as the relationship between the actual exhaust temperature change state and the target exhaust temperature, the adjustment range of the electronic expansion valve is adjusted and narrowed in real time, so that the actual exhaust temperature quickly reaches the target exhaust temperature, enabling the unit to reach a stable state more quickly and efficiently, and avoiding the long-term large fluctuations of the electronic expansion valve, which may affect the performance and reliability of the unit; in this embodiment, as long as both Condition 1 and Condition 2 are met, the upper and lower limit control of the opening of the electronic expansion valve is exited or not entered. On the contrary, the opening limit control process of the electronic expansion valve is entered. After the opening limit control process of the electronic expansion valve is started, it is necessary to determine how to expand or narrow the adjustment range of the electronic expansion valve by comparing the current exhaust temperature range interval with the target exhaust temperature Pdo n . Among them, each time the opening limit control of the electronic expansion valve is entered, the maximum exhaust temperature Pdmax n-1 and the minimum exhaust temperature Pdmin n-1 obtained last time are cleared, and the current maximum exhaust temperature Pdmax n and the current minimum exhaust temperature Pdmin n are re-obtained, and the loop operation is performed to ensure the accuracy of the data, and thus the purpose of precise control is achieved.

[0039] Specifically, when the unit receives the first startup command, the electronic expansion valve is reset and the initial opening of the electronic expansion valve is determined based on the ambient temperature value. After the compressor starts, the electronic expansion valve maintains the initial opening for 3 minutes. After 3 minutes, the opening of the electronic expansion valve is automatically adjusted according to the exhaust target value, and at the same time, the current maximum opening EXVmax n of the current electronic expansion valve and the current minimum opening EXVmin n are continuously detected and recorded. The corresponding values of the ambient temperature and the initial opening are as follows:

[0040]

[0041] The currently detected maximum opening EXVmax of the electronic expansion valve during the first startupn As the upper limit value EXVlimitmax of the first electronic expansion valve n the current minimum opening EXVmin of the electronic expansion valve at the first startup is detected n as the lower limit value EXVlimitmin of the first electronic expansion valve n and the upper limit value EXVlimitmax of the first electronic expansion valve n and the lower limit value EXVlimitmin of the first electronic expansion valve n are used as the upper and lower limit values EXVlimitmax n-1 and EXVlimitmin of the next basic electronic expansion valve n-1 .

[0042] Among them, the specific steps for adjusting the opening limit of the electronic expansion valve are as follows:

[0043] Each time the opening limit control of the electronic expansion valve is entered, the opening limit value of the previous electronic expansion valve is obtained; based on the opening limit value of the previous electronic expansion valve and the limit adjustment amount ΔEXV of the electronic expansion valve obtained through the calculation formula, the opening limit control of the current electronic expansion valve is adjusted. Specifically, is the adjustment amount required for the electronic expansion valve for every 1°C change in the actual exhaust temperature is the difference between the middle value of the upper and lower limits of the actual exhaust temperature fluctuation and the target exhaust temperature

[0044] In this embodiment, if there is no requirement for precise control, the opening limit range of the electronic expansion valve is adjusted separately according to the following conditions:

[0045] Control 1: If Pdmin n ≥Pdo n , then EXVlimitmax n =EXVlimitmax n-1 +ΔEXV, EXVlimitmin n =EXVlimitmin n-1 +ΔEXV; under this condition, as Figure 1 shown, Pdmin n ≥Pdo n , it indicates that the actual minimum exhaust temperature is higher than the target temperature, and the electronic expansion valve is adjusted within a relatively small range. At this time, the unit is prone to overheating and malfunction, so it is necessary to increase the opening of the electronic expansion valve. In the traditional solution, based on the actual exhaust temperature, after increasing a certain value of the opening of the electronic expansion valve, this value is used as a fixed value. However, in this technical solution, the opening limit (range) of the electronic expansion valve is increased as a whole, and the valve step value can vary within this limit range

[0046] Control 2: If Pdmax n > Pdo n > Pdmin n , then for the control under this condition, a constant value is introduced, and based on the ratio of ΔEXV to the constant value, adjustments are made on the upper and lower limits of the previous electronic expansion valve; although the target exhaust temperature is within the minimum and maximum ranges of the actual exhaust temperature in this case, due to the fluctuation of the actual exhaust temperature, there may be liquid carry-back in the suction gas, large fluctuations in the unit capacity, high power consumption of the whole machine, and poor effects. In the traditional solution, after adjusting a fixed value of the opening of the electronic expansion valve based on the actual exhaust temperature, this fixed value is used as a constant value. However, since the exhaust temperature of the unit continues to fluctuate, it indicates that the adjustment change amount of the electronic expansion valve is not suitable for the current unit state; while in this technical solution, the upper limit (range) or lower limit (range) or upper and lower limits (range) of the adjustment limit of the electronic expansion valve are continuously adjusted, thereby making the electronic expansion valve gradually tend to be stable.

[0047] Control 3: If Pdmax n ≤ Pdo n , then EXVlimitmax n = EXVlimitmax n-1 - ΔEXV, EXVlimitmin n = EXVlimitmin n-1 - ΔEXV; This condition is exactly the opposite of the above Pdmin n ≥ Pdo n , so it is necessary to reduce the opening limit (range) of the electronic expansion valve.

[0048] For further optimization, to meet the requirement of precise control, on the basis of the condition that Pdmax n > Pdo n > Pdmin n , additional conditions are added to achieve it, specifically as follows:

[0049] Control 2.1: If Pdmax n > Pdo n > Pdmin n and Pdmax n - Pdo n > Pdo n - Pdmin n , then EXVlimitmin n = EXVlimitmin n-1 +(ΔEXV / b);

[0050] Control 2.2: If Pdmax n > Pdo n > Pdminn and Pdmax n -Pdo n = Pdo n -Pdmin n , then EXVlimitmax n = EXVlimitmax n-1 × c, EXVlimitmin n = EXVlimitmin n-1 × c;

[0051] Control Two.3: If Pdmax n > Pdo n > Pdmin n and Pdmax n -Pdo n < Pdo n -Pdmin n , then EXVlimitmax n = EXVlimitmax n-1 -(ΔEXV / b);

[0052] where b is a constant, the value determined according to different unit configurations (can be set to 1, 2, 3, 4... etc.); c is a variable, and the range of c is from 10% to 100%.

[0053] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are only examples and do not limit the present invention.

[0054] The object of the present invention has been fully and effectively achieved. The functions and structural principles of the present invention have been shown and described in the embodiments. Without departing from the said principles, the embodiments of the present invention can have any deformation or modification.

Claims

1. An electronic expansion valve adjustment method based on the exhaust temperature limit, characterized in that, Including the following steps: The unit starts up and runs, and a target exhaust gas temperature Pdo is set n ; Obtain the maximum current exhaust temperature Pdmax n and the minimum current exhaust temperature Pdmin n , through the maximum current exhaust temperature Pdmax n and the minimum current exhaust temperature Pdmin n are respectively compared with the target exhaust temperature Pdo n to adjust the opening limit control of the electronic expansion valve; Obtain the maximum opening EXVmax of the current electronic expansion valve n and the minimum opening EXVmin of the current electronic expansion valve n , and determine not to enter the opening limit control of the electronic expansion valve while meeting the following conditions: Condition 1: EXVmax n-2 -EXVmin n-2 ≥EXVmax n-1 -EXVmin n-1 ≥EXVmax n -EXVmin n ; Condition 2: EXVmax n -EXVmin n ≤ a, where a is a constant and can be adjusted according to the requirements of different systems.

2. The electronic expansion valve adjustment method according to claim 1, characterized in that, When the unit receives the first start-up command, the electronic expansion valve resets and determines the initial opening degree of the electronic expansion valve based on the ambient temperature value. After the compressor starts, the electronic expansion valve maintains the initial opening degree for 3 minutes. After operation, it automatically adjusts the opening degree of the electronic expansion valve according to the exhaust target value, and continuously detects and records the maximum opening degree EXVmax of the current electronic expansion valve at the same time n and the minimum opening degree EXVmin of the current electronic expansion valve n .

3. The electronic expansion valve adjustment method according to claim 2, characterized in that, Each time entering the opening limit control of the electronic expansion valve, obtain the previous opening limit of the electronic expansion valve; adjust the current opening limit control of the electronic expansion valve based on the previous opening limit of the electronic expansion valve and the limit adjustment amount ΔEXV of the electronic expansion valve obtained through the calculation formula.

4. The electronic expansion valve adjustment method according to claim 3, characterized in that, Determine the opening limit value of the first electronic expansion valve: Detect the maximum opening EXVmax of the current electronic expansion valve at the first startup n as the upper limit value EXVlimitmax of the first electronic expansion valve n , detect the minimum opening EXVmin of the current electronic expansion valve at the first startup n as the lower limit value EXVlimitmin of the first electronic expansion valve n , and the upper limit value EXVlimitmax of the first electronic expansion valve n and the lower limit value EXVlimitmin of the first electronic expansion valve n serve as the upper and lower limit values EXVlimitmax n-1 and EXVlimitmin n-1 of the basic electronic expansion valve for the next time.

5. The electronic expansion valve adjustment method according to claim 3, characterized in that, Among them, the calculation formula for the restricted adjustment amount of the electronic expansion valve is 6. The electronic expansion valve adjustment method according to claim 3, characterized in that, The specific opening limit control of the electronic expansion valve includes the following control steps: If Pdmin n ≥Pdo n , then EXVlimitmax n = EXVlimitmax n-1 +ΔEXV, EXVlimitmin n = EXVlimitmin n-1 +ΔEXV; If Pdmax n > Pdo n > Pdmin n , then for the control under this condition, a constant value is introduced, and based on the upper and lower limits of the previous electronic expansion valve, adjustment is made through the ratio of ΔEXV to the constant value; If Pdmax n ≤Pdo n , then EXVlimitmax n = EXVlimitmax n-1 -ΔEXV, EXVlimitmin n = EXVlimitmin n-1 -ΔEXV.

7. The electronic expansion valve adjustment method according to claim 6, characterized in that, If Pdmax n > Pdo n > Pdmin n and Pdmax n - Pdo n > Pdo n - Pdmin n , then EXVlimitmin n = EXVlimitmin n-1 +(ΔEXV / b); If Pdmax n > Pdo n > Pdmin n and Pdmax n - Pdo n = Pdo n - Pdmin n , then EXVlimitmax n = EXVlimitmax n-1 ×c, EXVlimitmin n = EXVlimitmin n-1 ×c; If Pdmax n > Pdo n > Pdmin n and Pdmax n - Pdo n < Pdo n - Pdmin n , then EXVlimitmax n = EXVlimitmax n-1 -(ΔEXV / b); where b is a constant, the value determined according to different unit configurations; c is a variable, and the range of c is from 10% to 100%.

8. The electronic expansion valve adjustment method according to claim 1, characterized in that, Each time the opening limit control of the electronic expansion valve is entered, the maximum value of the exhaust gas temperature obtained last time is recorded as Pdmax n-1 , the minimum value of the exhaust gas temperature obtained last time is recorded as Pdmin n-1 , after entering the control, Pdmax n-1 and Pdmin n-1 are cleared, and the current maximum value of the exhaust gas temperature Pdmax n and the current minimum value of the exhaust gas temperature Pdmin n are re-obtained, and the operation is repeated in a loop.

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