A control method for a vehicle air conditioning system

Abstract

The present invention discloses a method for controlling a vehicle air conditioning system. The method comprises: calculating the system's optimal operating high-pressure pressure using an optimal pressure formula; setting a lower limit, an upper limit, and an initial operating opening of an electronic expansion valve; and adjusting the electronic expansion valve opening using integral control calculations. When the actual operating pressure of the refrigeration and air conditioning system is adjusted to the optimal operating high-pressure pressure, electronic expansion valve regulation is stopped, and it is determined whether the electronic expansion valve opening is within an interval between the upper and lower limits. By combining formula-fitting and calculation of the optimal system operating high-pressure pressure control with ambient temperature interval control, the present invention achieves stable operation of a carbon dioxide air conditioner at optimal energy efficiency in different ambient temperature intervals. By setting the lower limit, upper limit, and initial operating opening of the throttling element in different ambient temperature intervals, reliable operation under extreme operating conditions is ensured.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle variable frequency air conditioning control, and in particular to a vehicle air conditioning system control method. Background Art

[0002] The current refrigeration industry is increasingly mature. The damage to the ozone layer and the greenhouse effect caused by conventional refrigerants are urgent problems that need to be solved. Most synthetic refrigerants have different degrees of damage to the ozone layer and their global warming potential is also at a high level. Carbon dioxide, as a natural refrigerant, is the most ideal refrigerant substitute. Carbon dioxide refrigerant has the advantages of being safe, non-toxic, non-flammable, with an ozone depletion potential of 0 and a global warming potential of 1. Carbon dioxide air conditioners are becoming more and more popular in the industry.

[0003] Most of the existing carbon dioxide air conditioners on the market can only perform a single cooling function, have a single control function, adapt to a limited number of working conditions, and cannot give full play to the advantages of carbon dioxide refrigerant in ultra-low temperature heating.

[0004] Typically used in small air conditioning systems such as passenger cars, CO2 is rarely used in large air conditioning systems. Therefore, a new control method is needed to ensure that the unit can operate normally without protection issues even under extreme operating conditions. Summary of the Invention

[0005] In order to solve the above problems, a vehicle air conditioning system control method is provided.

[0006] The object of the present invention is achieved in the following manner:

[0007] A vehicle air conditioning system control method, the method comprising:

[0008] S1: Calculate the optimal operating high pressure of the system through the optimal pressure formula;

[0009] S2: Divide the ambient temperature range in which the air conditioning system can operate into multiple groups of ambient temperature sub-ranges; set the lower limit, upper limit and initial operating opening of the electronic expansion valve in different ambient temperature sub-ranges;

[0010] S3: The system adjusts the opening of the electronic expansion valve through integral control calculation to adjust the actual operating pressure of the refrigeration and air conditioning system to the optimal operating high pressure. When the actual operating pressure matches the optimal operating high pressure, the electronic expansion valve adjustment is stopped and it is determined whether the opening of the electronic expansion valve is within the upper and lower limits of the electronic expansion valve opening set in the current ambient temperature sub-range;

[0011] S4: If the pressure exceeds the upper limit or falls below the lower limit, the electronic expansion valve is controlled to adjust to the range between the upper limit and the lower limit.

[0012] The optimal pressure formula includes an optimal pressure formula for cooling mode and an optimal pressure formula for heating mode.

[0013] The optimal pressure formula for the cooling mode is: P 优 =AT 环 +BP 频 +CT 内 +D, where T 环 Indicates the ambient temperature, P 频 Indicates the compressor frequency, T 内 represents the temperature inside the car. A, B, C, and D are constants obtained through test fitting.

[0014] The optimal pressure formula for heating mode is P 优 =ET 环 +FT 冷出 +GP 频 +HT 内 +I, where T 环 Indicates the ambient temperature, T 冷出 Indicates the air cooler outlet temperature, P 频 Indicates the compressor frequency, T 内 represents the temperature inside the car. E, F, G, H, and I are constants obtained through test fitting.

[0015] Beneficial effects of the present invention: The present invention combines the high-pressure control of the optimal system operation by fitting the formula and the control of the ambient temperature division interval, so as to realize the stable operation of the carbon dioxide air conditioner with the optimal energy efficiency in different ambient temperature ranges, and ensures the reliable operation under extreme working conditions by setting the lower limit, upper limit and initial operating opening of the throttling element in different ambient temperature ranges. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a control flow chart of the present invention. DETAILED DESCRIPTION

[0017] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] It should be noted that the following detailed description is illustrative and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same technical meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0019] like Figure 1 As shown, a vehicle air conditioning system control method includes:

[0020] S1: Calculate the optimal operating high pressure of the system through the optimal pressure formula;

[0021] S2: Divide the ambient temperature range in which the air conditioning system can operate into multiple groups of ambient temperature sub-ranges; set the lower limit, upper limit, and initial operating opening of the electronic expansion valve within each ambient temperature sub-range; the initial operating opening is confirmed by measuring parameters related to the middle temperature of the temperature range (for example, in the 20°C-30°C range, 25°C is used as the test temperature for confirming the initial opening and other parameters). The confirmation method is to determine the optimal operating frequency and operating opening based on the actual vehicle load at this ambient temperature, and this optimal opening is used as the initial operating opening for this temperature range;

[0022] S3: The system adjusts the opening of the electronic expansion valve through integral control calculation to adjust the actual operating pressure of the refrigeration and air conditioning system to the optimal operating high pressure. When the actual operating pressure matches the optimal operating high pressure, the electronic expansion valve adjustment is stopped and it is determined whether the opening of the electronic expansion valve is within the upper and lower limits of the electronic expansion valve opening set in the current ambient temperature sub-range;

[0023] S4: If the pressure exceeds the upper limit or falls below the lower limit, the electronic expansion valve is controlled to adjust to the range between the upper limit and the lower limit.

[0024] The optimal pressure formula for cooling mode is: P 优 =AT 环 +BP 频 +CT 内 +D, where T 环 Indicates the ambient temperature, P 频 Indicates the compressor frequency, T 内 represents the temperature inside the vehicle, A, B, C, and D are constants obtained through test fitting. The compressor is a variable frequency compressor.

[0025] A, B, C, and D are obtained through test fitting. Specifically, the corresponding positions are marked in the coordinates according to the actual test data, and the coefficient values ​​in the formula are adjusted to obtain the curve that is closest to the measured data, thereby determining the best fitting coefficient.

[0026] The actual test data refers to the best heat transfer, energy efficiency and temperature point data at the selected ambient temperature in each interval. The pressure under this state is determined as the optimal pressure, and then the coefficients are fitted one by one according to the data, such as P 频 The coefficient is calculated by adjusting the frequency under the same operating conditions while keeping other parameters constant to determine how much the measured pressure changes every 5Hz or 10Hz. The coefficient is then determined based on the change, and the coefficient reflects the rate of pressure change. Simply put, the coefficient is determined one by one while keeping other parameters constant. The test data is the measured pressure, frequency, and temperature. After determining the coefficient, the optimal pressure is inferred from the formula to verify whether it is consistent with the measured data. Based on the actual test situation, the coefficient is then fine-tuned to ensure that the measured data matches the calculated data.

[0027] After determining the formula coefficient, use the formula to calculate by substituting the current sensor detection data into the formula, and the actual ambient temperature T tested by the sensor is obtained. 环 , Current actual operating frequency P 频 、Current actual temperature in the car T 内 .

[0028] The optimal pressure formula for heating mode is P 优 =ET 环 +FT 冷出 +GP 频 +HT 内 +I, where T 冷出 Indicates the outlet temperature of the external heat exchanger, P 频 Indicates the compressor frequency, T 内 represents the temperature inside the car. E, F, G, H, and I are constants obtained through test fitting.

[0029] E, F, G, H, and I are constants obtained through test fitting. Specifically, the corresponding positions are marked in the coordinates according to the actual test data, and the curve closest to the measured data is obtained by adjusting the coefficient values ​​in the formula, thereby determining the best fitting coefficient.

[0030] Actual test data refers to debugging the optimal heat transfer, energy efficiency, and data at each temperature point under the ambient temperature selected in each interval. The pressure under this state is determined as the optimal pressure. Then, the coefficients are fitted one by one according to the data. For example, the coefficient of P frequency is determined by adjusting the frequency to determine how much the measured pressure changes every 5Hz or 10Hz while other parameters remain unchanged under the same working conditions. The size of the coefficient is determined based on the change. The coefficient reflects the size of the pressure change rate. In simple terms, the coefficients are determined one by one while the other parameters remain unchanged. The test data are the measured pressure, frequency, and temperature. After the coefficients are determined, the optimal pressure is reversed according to the formula to verify whether it is consistent with the measured data. Based on the actual test situation, the coefficients are fine-tuned to match the measured data with the calculated data.

[0031] After determining the formula coefficients, the formula is used to calculate by substituting the current sensor detection data into the formula, and the sensor tests the actual ambient temperature Tring, the current actual operating frequency Pfrequency, the current actual temperature inside the vehicle Tinner, and the actual test air cooler outlet temperature Tcoldout.

[0032] Cooling mode control is as follows:

[0033] By monitoring the current operating condition data through sensors, the above formula calculates the optimal operating pressure of the system under the current operating conditions. The opening of the electronic expansion valve is adjusted through integral control calculation to adjust the actual operating pressure of the air-conditioning system to the optimal pressure calculated by the formula fitting. When the calculated pressure matches the actual operating pressure, the electronic expansion valve adjustment is stopped to maintain stable operation in the current state.

[0034] The ambient temperature is divided into several intervals according to the difference, T1~T2, T2~T3 to T N-1 ~T N Equal interval, when T1≤T 环 When T2 is less than the opening of the electronic expansion valve, the opening degree is [K 11 ~K12】, where the lower limit opening is the minimum opening, the upper limit opening is the maximum opening, and the initial opening is the startup opening. During normal operation, the system ensures that the actual operating pressure matches the calculated optimal pressure by integrally adjusting the electronic expansion valve. The upper and lower limits of the interval opening are to ensure that the unit can operate normally without protection under special harsh conditions. The setting control is shown in the following table:

[0035] interval Lower limit opening / B Upper limit opening / B Initial opening / B <![CDATA[T 环 ≥T N+1 ]]> <![CDATA[K N11 ]]> <![CDATA[K N12 ]]> <![CDATA[K N13 ]]> <![CDATA[T N-1 ≤T 环 <T N ]]> <![CDATA[K N1 ]]> <![CDATA[K N2 ]]> <![CDATA[K N3 ]]> … … … … <![CDATA[T1≤T 环 <T2]]> <![CDATA[K 21 ]]> <![CDATA[K 22 ]]> <![CDATA[K 23 ]]> <![CDATA[T 环 <T1]]> <![CDATA[K 11 ]]> <![CDATA[K 12 ]]> <![CDATA[K 13 ]]>

[0036] Heating mode control is as follows:

[0037] By monitoring the current operating condition data through sensors, the above formula calculates the optimal operating pressure of the system under the current operating conditions. The opening of the electronic expansion valve is adjusted through integral control calculation to adjust the actual operating pressure of the air-conditioning system to the optimal pressure calculated by the formula fitting. When the calculated pressure matches the actual operating pressure, the electronic expansion valve adjustment is stopped to maintain stable operation in the current state.

[0038] The ambient temperature is divided into several intervals according to the difference, T1~T2, T2~T3 to T M-1 ~T M In the same interval and with the same refrigeration control, the opening of the electronic expansion valve is in the set range. During normal operation, the system ensures that the actual operating pressure matches the calculated optimal pressure by integrally adjusting the electronic expansion valve. The upper and lower limits of the interval opening are to ensure that the unit can operate normally without protection under special harsh conditions. The setting control is shown in the following table:

[0039] interval Lower limit opening / B Upper limit opening / B Initial opening / B <![CDATA[T 环 ≥T M+1 ]]> <![CDATA[K M11 ]]> <![CDATA[K M12 ]]> <![CDATA[K M13 ]]> <![CDATA[T M-1 ≤T 环 <T M ]]> <![CDATA[K M1 ]]> <![CDATA[K M2 ]]> <![CDATA[K M3 ]]> … … … … <![CDATA[T1≤T 环 <T2]]> <![CDATA[K 21 ]]> <![CDATA[K 22 ]]> <![CDATA[K 23 ]]> <![CDATA[T 环 <T1]]> <![CDATA[K 11 ]]> <![CDATA[K 12 ]]> <![CDATA[K 13 ]]>

[0040] The above is only a preferred embodiment of the present invention. It should be pointed out that for those skilled in the art, several changes and improvements can be made without departing from the overall concept of the present invention, and these should also be regarded as the scope of protection of the present invention.

Claims

1. A vehicle air conditioning system control method, characterized in that: The method comprises: S1: Calculate the optimal operating high pressure of the system through the optimal pressure formula; The optimal pressure formula includes the optimal pressure formula for cooling mode and the optimal pressure formula for heating mode; The optimal pressure formula for the cooling mode is: P 优 =AT 环 +BP 频 +CT 内 +D, where T 环 Indicates the ambient temperature, P 频 Indicates the compressor frequency, T 内 represents the temperature inside the car, A, B, C, and D are constants obtained through test fitting; The optimal pressure formula for heating mode is: P 优 =ET 环 + FT 冷出 +GP 频 +HT 内 +I, where T 环 Indicates the ambient temperature, T 冷出 Indicates the air cooler outlet temperature, P 频 Indicates the compressor frequency, T 内 represents the temperature inside the car, E, F, G, H, and I are constants obtained through test fitting; S2: Divide the ambient temperature range in which the air conditioning system can operate into multiple groups of ambient temperature sub-ranges; set the lower limit, upper limit and initial operating opening of the electronic expansion valve in different ambient temperature sub-ranges; S3: The system adjusts the opening of the electronic expansion valve through integral control calculation to adjust the actual operating pressure of the refrigeration and air conditioning system to the optimal operating high pressure. When the actual operating pressure matches the optimal operating high pressure, the electronic expansion valve adjustment is stopped and it is determined whether the opening of the electronic expansion valve is within the upper and lower limits of the electronic expansion valve opening set in the current ambient temperature sub-range; S4: If the pressure exceeds the upper limit or falls below the lower limit, the electronic expansion valve is controlled to adjust to the range between the upper limit and the lower limit.

Images