Fault diagnosis and downgrade method for pressure closed loop of tracked vehicle controlled by solenoid valve

Abstract

The present invention belongs to the technical field of hydraulic control for special vehicles, and specifically relates to a method for diagnosing and downgrading pressure closed-loop faults in solenoid-controlled tracked vehicles. The method introduces current closed-loop control, adjusting the duty cycle based on the actual solenoid valve current to ensure current stability. Simultaneously, the method also introduces pressure closed-loop control to adjust the solenoid valve current in real time to ensure pressure stability and improve shifting smoothness. On the one hand, the method implements fault diagnosis and fault location determination under dual closed-loop pressure and current control; on the other hand, it ensures a downgraded strategy that takes into account sensor or signal source anomalies, ensuring vehicle safety.

Description

Technical Field

[0001] The present invention belongs to the technical field of special vehicle hydraulic control, and in particular relates to a method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve. Background Art

[0002] Special vehicle transmission systems typically use solenoid valves for shift control. These valves control oil filling in the hydraulic cylinder to adjust friction plate engagement, thereby enabling gear shifts. Proportional solenoid valves, commonly used in special vehicles, control the valve core position by controlling the current flowing through the coil, adjusting the amount of oil flowing through it. This in turn controls the oil pressure in the hydraulic cylinder and, in turn, the degree of friction plate engagement. Compared to on-off solenoid valves, proportional solenoid valves can further control the oil filling process, effectively mitigating shift shock. A common current control method uses PWM modulation, outputting a PWM modulation signal at a specific frequency and adjusting the duty cycle to control the current through the solenoid valve. Factors such as coil heating and oil temperature can cause variations in solenoid current for the same duty cycle. In this case, current closed-loop control is necessary to adjust the duty cycle based on the actual solenoid current to ensure current stability. However, even with the same solenoid current, variations in oil viscosity can cause variations in hydraulic pressure output from the hydraulic cylinder, affecting the degree of friction plate engagement. Therefore, pressure closed-loop control is also necessary to adjust the solenoid current in real time to ensure pressure stability and improve shifting smoothness. Summary of the Invention

[0003] (1) Technical issues to be solved

[0004] The technical problem to be solved by the present invention is: how to provide a method for diagnosing and degrading pressure closed-loop faults of tracked vehicles based on solenoid valve control.

[0005] (2) Technical solution

[0006] To solve the above technical problems, the present invention provides a method for diagnosing and degrading a pressure closed-loop fault of a tracked vehicle controlled by a solenoid valve, the method being as follows:

[0007] Step 1: First, determine the oil pump speed status and confirm that the oil source has built up pressure;

[0008] Step 2: Calculate the pressure mean square error σ based on the sensor pressure sampling value P P ;

[0009] Step 3: If the pressure mean square error σ P If the pressure is less than the set threshold, the control mode is adjusted to the constant pressure mode, the pressure is controlled to be constant, and the expected current value is calculated according to the pressure PID algorithm;

[0010] Step 4: If the pressure mean square error σ PNot less than the set threshold, and then calculate the current mean square error σ based on the current sampling value I I ; In this case, it is judged that the pressure sensor or valve block is faulty;

[0011] Step 5: If the current mean square error σ I If the current is less than the set threshold, the control mode is adjusted to the constant current mode to control the current to be constant, and the expected PWM duty cycle is calculated according to the current PID algorithm;

[0012] Step 6: If the current mean square error σ I If the value is not less than the set threshold, the control mode is adjusted to the stable PWM output mode, and the PWM output value is set to a fixed value; at the same time, the mean square error σ of the actual PWM output value is calculated. PWM ; At this time, it is judged that the current sampling hardware is faulty;

[0013] Step 7: If the mean square error σ of the actual PWM output value PWM If it is less than the set threshold, the preset PWM duty cycle is output; otherwise, the output control mode is faulty and the PWM function is turned off; in this case, the fault is judged to be a microcontroller function failure.

[0014] According to the pressure closed loop fault diagnosis and degradation method, write the single chip microcomputer control program:

[0015] Step A: Program starts running;

[0016] Step B: Execute fault degradation strategy judgment, input the oil pump speed status, pressure sampling value, current sampling value, and PWM actual output value, and obtain the control mode and output;

[0017] Step C: Determine whether the control mode is a constant pressure mode, perform a pressure closed loop using the desired pressure value to obtain a current value, perform a current closed loop using the current value to obtain a PWM duty cycle, and output the PWM duty cycle;

[0018] Step D: Determine whether the control mode is a constant current mode, use a preset current value to perform a current closed loop to obtain a PWM duty cycle, and output the PWM duty cycle;

[0019] Step E: Determine that the control mode is stable PWM output and use a preset PWM duty cycle for output;

[0020] Step F: Determine that the control mode is faulty and turn off the PWM function;

[0021] Step G: The program is executed in a cyclical cycle.

[0022] (3) Beneficial effects

[0023] Compared with the existing technology, the present invention provides a method for pressure closed-loop fault diagnosis and degradation of tracked vehicles based on solenoid valve control. On the one hand, it realizes fault diagnosis under dual closed-loop control of pressure and current and determines the fault location; on the other hand, it can ensure the degradation strategy in the case of abnormal sensor or signal source to ensure vehicle safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a flow chart of the fault diagnosis and downgrade method of the present invention.

[0025] Figure 2 This is a flow chart of the single chip microcomputer software execution method in the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, content, and advantages of the present invention more clear, the specific implementation methods of the present invention are further described in detail below with reference to the accompanying drawings and examples.

[0027] To solve the above technical problems, the present invention provides a method for diagnosing and degrading a pressure closed-loop fault of a tracked vehicle controlled by a solenoid valve, the method being as follows:

[0028] Step 1: First, determine the oil pump speed status and confirm that the oil source has built up pressure;

[0029] Step 2: Calculate the pressure mean square error σ based on the sensor pressure sampling value P P ;

[0030] Step 3: If the pressure mean square error σ P If the pressure is less than the set threshold, the control mode is adjusted to the constant pressure mode, the pressure is controlled to be constant, and the expected current value is calculated according to the pressure PID algorithm;

[0031] Step 4: If the pressure mean square error σ P Not less than the set threshold, and then calculate the current mean square error σ based on the current sampling value I I ; In this case, it is judged that the pressure sensor or valve block is faulty;

[0032] Step 5: If the current mean square error σ I If the current is less than the set threshold, the control mode is adjusted to the constant current mode to control the current to be constant, and the expected PWM duty cycle is calculated according to the current PID algorithm;

[0033] Step 6: If the current mean square error σ I If the value is not less than the set threshold, the control mode is adjusted to the stable PWM output mode, and the PWM output value is set to a fixed value; at the same time, the mean square error σ of the actual PWM output value is calculated. PWM ; At this time, it is judged that the current sampling hardware is faulty;

[0034] Step 7: If the mean square error σ of the actual PWM output value PWM If it is less than the set threshold, the preset PWM duty cycle is output; otherwise, the output control mode is faulty and the PWM function is turned off; in this case, the fault is judged to be a microcontroller function failure.

[0035] According to the pressure closed loop fault diagnosis and degradation method, write the single chip microcomputer control program:

[0036] Step A: Program starts running;

[0037] Step B: Execute fault degradation strategy judgment, input the oil pump speed status, pressure sampling value, current sampling value, and PWM actual output value, and obtain the control mode and output;

[0038] Step C: Determine whether the control mode is a constant pressure mode, perform a pressure closed loop using the desired pressure value to obtain a current value, perform a current closed loop using the current value to obtain a PWM duty cycle, and output the PWM duty cycle;

[0039] Step D: Determine whether the control mode is a constant current mode, use a preset current value to perform a current closed loop to obtain a PWM duty cycle, and output the PWM duty cycle;

[0040] Step E: Determine that the control mode is stable PWM output and use a preset PWM duty cycle for output;

[0041] Step F: Determine that the control mode is faulty and turn off the PWM function;

[0042] Step G: The program is executed in a cyclical cycle.

[0043] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve, characterized in that: The method is as follows: Step 1: First, determine the oil pump speed status and confirm that the oil source has built up pressure; Step 2: Calculate the pressure mean square error σ based on the sensor pressure sampling value P P ; Step 3: If the pressure mean square error σ P If the pressure is less than the set threshold, the control mode is adjusted to the constant pressure mode, the pressure is controlled to be constant, and the expected current value is calculated according to the pressure PID algorithm; Step 4: If the pressure mean square error σ P Not less than the set threshold, and then calculate the current mean square error σ based on the current sampling value I I ; In this case, it is judged that the pressure sensor or valve block is faulty; Step 5: If the current mean square error σ I If the current is less than the set threshold, the control mode is adjusted to the constant current mode to control the current to be constant, and the expected PWM duty cycle is calculated according to the current PID algorithm; Step 6: If the current mean square error σ I If the value is not less than the set threshold, the control mode is adjusted to the stable PWM output mode, and the PWM output value is set to a fixed value; at the same time, the mean square error σ of the actual PWM output value is calculated. PWM ; At this time, it is judged that the current sampling hardware is faulty; Step 7: If the mean square error σ of the actual PWM output value PWM If it is less than the set threshold, the preset PWM duty cycle is output, otherwise the output control mode is faulty and the PWM function is turned off; in this case, the fault is judged to be a microcontroller function failure.

2. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: According to the pressure closed loop fault diagnosis and degradation method, write the single chip microcomputer control program: Step A: Program starts running; Step B: Execute fault degradation strategy judgment, input the oil pump speed status, pressure sampling value, current sampling value, and PWM actual output value, and obtain the control mode and output; Step C: Determine whether the control mode is a constant pressure mode, perform a pressure closed loop using the desired pressure value to obtain a current value, perform a current closed loop using the current value to obtain a PWM duty cycle, and output the PWM duty cycle; Step D: Determine whether the control mode is a constant current mode, use a preset current value to perform a current closed loop to obtain a PWM duty cycle, and output the PWM duty cycle; Step E: Determine that the control mode is stable PWM output and use a preset PWM duty cycle for output; Step F: Determine that the control mode is faulty and turn off the PWM function; Step G: The program is executed in a cyclical cycle.

3. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: The method belongs to the technical field of special vehicle hydraulic control.

4. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: The method introduces current closed-loop control and adjusts the duty cycle according to the actual solenoid valve current to ensure current stability.

5. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: The method introduces pressure closed-loop control to adjust the solenoid valve current in real time to ensure pressure stability and improve shifting smoothness.

6. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: The method realizes fault diagnosis under pressure and current dual closed-loop control and determines the fault location.

7. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: The method can ensure that a degraded usage strategy is taken into account in the event of abnormality of a sensor or signal source, thereby ensuring vehicle safety.

8. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: In step 5, the desired PWM duty cycle is calculated according to the current PID algorithm.

9. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: In step 3, the expected current value is calculated according to the pressure PID algorithm.

10. The method for diagnosing and degrading pressure closed-loop faults of a tracked vehicle controlled by a solenoid valve as claimed in claim 1, wherein: In step 7, if the mean square error σ of the actual PWM output value PWM If it is less than the set threshold, the preset PWM duty cycle is output; otherwise, the output control mode is faulty and the PWM function is turned off; in this case, the fault is judged to be a microcontroller function failure.

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