Method for treating internal liquid leakage of electromagnetic valve for agricultural machinery

Abstract

The invention discloses a method for treating internal leakage of an electromagnetic valve for agricultural machinery. The method comprises the steps that a left-turning leakage rotating speed threshold value and a right-turning leakage rotating speed threshold value of the agricultural machinery are determined through a field test; performing an electromagnetic valve liquid leakage test on the agricultural machine in operation, in the test process, acquiring front wheel rotation angle data of the agricultural machine in real time at a set time interval to obtain rotation angle data corresponding to a plurality of acquisition moments, and further calculating to obtain a front wheel rotation angle change rate between adjacent acquisition moments; according to whether the front wheel of the agricultural machine continues to rotate when the PWM duty ratio sent by the controller is 50%, whether liquid leakage exists in the electromagnetic valve or not is judged; according to the method, the liquid leakage rotating speed threshold value, the liquid leakage judging condition of the electromagnetic valve and the PWM duty ratio optimal change delta PWM enabling a control valve element to return to the mechanical middle position are set, so that the internal liquid leakage of the electromagnetic valve is rapidly treated. The method has the advantages that the leakage rotating speed threshold value, the liquid leakage judging condition of the electromagnetic valve and the PWM duty ratio optimal change delta PWM enabling the control valve element to return to the mechanical middle position are set, and accordingly the internal liquid leakage of the electromagnetic valve can be quickly treated.

Description

Technical Field

[0001] The invention belongs to the technical field of solenoid valves and relates to a method for processing internal liquid leakage of a solenoid valve for agricultural machinery. Background Art

[0002] A solenoid valve is a device that uses the electromagnetic field as the principle to change the size and direction of hydraulic flow by controlling the position of the valve core. Solenoid valves for agricultural machinery are usually not as accurate as automotive-grade solenoid valves. In some use scenarios where precision is not required, such as agricultural machinery steering, the controller can send a PWM (Pulse Width Modulation) duty cycle to the solenoid valve to change the direction and flow of the steering hydraulic oil, thereby realizing the agricultural machinery steering function. The commonly used industrial-grade solenoid valve is a three-position four-way proportional directional solenoid valve, which consists of a valve body with a mounting surface, a control valve core, a compression spring, a solenoid coil, and an integrated amplifier. Under normal circumstances, after the solenoid coil is powered off, the control valve core will be kept in the mechanical center position by the compression spring; when the solenoid coil is powered on, the valve core begins to move. If the control valve core is not completely in the absolute mechanical center position after the solenoid coil is powered off, internal leakage of the solenoid valve will occur. During the use of solenoid valves for agricultural machinery, it is difficult to ensure that the valve core is completely in the absolute middle position through the electromagnetic coil and the spring. Therefore, internal leakage is inevitable during the use of the solenoid valves for agricultural machinery. As the years of use increase, the leakage will become more serious. Leakage will cause the front wheels of the agricultural machinery to be unable to maintain the same angle for a long time, affecting the steering effect. Therefore, it is very necessary to correctly identify the leakage condition and deal with it, but the existing technology lacks the corresponding treatment method. Summary of the invention

[0003] In view of the defects and shortcomings in the prior art, the present invention provides a method for processing internal liquid leakage of an electromagnetic valve for agricultural machinery, so as to solve the technical problem of poor steering effect caused by the lack of a method for processing internal liquid leakage of an electromagnetic valve for agricultural machinery in the prior art.

[0004] To achieve the above object, the present invention adopts the following technical scheme:

[0005] A method for processing internal liquid leakage of a solenoid valve for agricultural machinery comprises the following steps:

[0006] Step 1: Determine the left-turn leakage speed threshold and the right-turn leakage speed threshold of the agricultural machinery through field tests;

[0007] Step 2: Perform a solenoid valve leakage test on the agricultural machinery in operation. During the test, collect the front wheel angle data of the agricultural machinery in real time at a set time interval to obtain the angle data corresponding to multiple collection moments, and then calculate the front wheel angle change rate between adjacent collection moments;

[0008] Step 3: Determine whether there is leakage in the solenoid valve according to whether the front wheel of the agricultural machine continues to rotate when the PWM duty cycle sent by the controller is 50%;

[0009] If the front wheel of the agricultural machine does not continue to rotate, it is determined that there is no leakage in the solenoid valve;

[0010] If the front wheel of the agricultural machinery continues to rotate, it is determined that the solenoid valve is leaking, and internal leakage treatment is performed according to the set leakage treatment strategy, including:

[0011] If the front wheel of the agricultural machinery continues to turn left and the current front wheel angle change rate is greater than the left turn leakage speed threshold determined in step 1, it is determined to be a left turn leakage, and the PWM duty cycle is adjusted to 0.5-deltaPWM;

[0012] If the front wheel of the agricultural machinery continues to turn right and the current front wheel angle change rate is less than the right turn leakage speed threshold determined in step 1, it is determined to be a right turn leakage, and the PWM duty cycle is adjusted to 0.5+deltaPWM.

[0013] The present invention also has the following technical features:

[0014] Specifically, the time interval set in step 2 is 10 ms.

[0015] Furthermore, the front wheel turning angle change rate between adjacent collection moments in step 2 is determined by the following formula:

[0016] Y=(θ (i+1) -θ (i) ) / △ t

[0017] In the formula,

[0018] Y is the rate of change of the front wheel turning angle;

[0019] θ (i+1) is the front wheel steering angle data collected at the i+1th sampling time, in degrees, where i is a positive integer;

[0020] θ (i) is the front wheel steering angle data collected at the i-th sampling moment, in degrees;

[0021] △ t is the set time interval in ms.

[0022] Furthermore, △ PWM is determined by the following formula:

[0023]

[0024] In the formula,

[0025] deltaPWM is the change in PWM duty cycle;

[0026] Y(t) is the front wheel speed corresponding to the t-th sampling time point, in deg / s;

[0027] K1 is the proportional gain coefficient;

[0028] K2 is the integral gain coefficient;

[0029] K3 is the differential gain coefficient.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The method of the present invention first determines the left-turn leakage speed threshold and the right-turn leakage speed threshold of the agricultural machinery through field tests, and then obtains the front wheel angle data of the agricultural machinery in real time according to the set time interval, obtains the front wheel angle change rate between adjacent collection moments, and the set leakage judgment standard, determines whether the solenoid valve has leakage, and then performs progressive processing according to the set leakage processing strategy, determines the PWM duty cycle change required to repair the leakage under the current solenoid valve leakage condition, and then adjusts the PWM duty cycle to make the solenoid valve control valve core return to the mechanical middle position, so that the internal leakage phenomenon of the solenoid valve is significantly improved, and the operation is simple and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is a flow chart of the present invention;

[0033] Figure 2 This is the PWM and front wheel angle change trend diagram when the solenoid valve leaks;

[0034] Figure 3 It is a trend diagram of PWM and front wheel angle changes after the leakage treatment is performed using the method of the present invention.

[0035] The present invention is described in detail below with reference to the accompanying drawings and specific implementation methods. DETAILED DESCRIPTION

[0036] In accordance with the above technical scheme, the specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent changes made on the basis of the technical scheme of this application fall within the protection scope of the present invention. The present invention is further described in detail below in conjunction with the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work should belong to the scope of protection of the present invention.

[0037] It should be noted that the terms "including" and "having" and any variations thereof in the present invention are intended to cover non-exclusive inclusions. For example, a process, method, system, product or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products or apparatuses.

[0038] The following are explanations of the terms involved in the invention:

[0039] Front wheel angle change rate: the ratio between the difference in front wheel angles collected at adjacent sampling moments and the set data collection time interval.

[0040] Example 1

[0041] The prerequisite for dealing with leakage is to identify the working condition of leakage inside the solenoid valve during the steering process of agricultural machinery. In this embodiment, when the industrial-grade solenoid valve is applied to agricultural machinery, TAS (Torque Angle Sensor) is installed on the steering drive shaft or the front wheel of the agricultural machinery. The TAS is electrically connected to a controller. After preliminary calibration processing, the voltage signal output by the torque angle sensor can be converted into an angle signal to realize the collection of the front wheel angle data of the agricultural machinery. Then, based on the collected front wheel angle data, the front wheel angle change rate (front wheel speed) can be calculated.

[0042] Following the above technical solution, Figure 1 As shown, this embodiment provides a method for processing internal liquid leakage of a solenoid valve for agricultural machinery, comprising the following steps:

[0043] Step 1: Determine the left-turn leakage speed threshold and the right-turn leakage speed threshold of the agricultural machinery through field tests;

[0044] In the field test, the agricultural machinery is stopped in place. When the PWM duty cycle sent by the controller is 50% (i.e., the controller does not send a steering command), if the front wheel of the agricultural machinery is observed to turn left, it means that the valve core of the agricultural machinery solenoid valve is not in the mechanical neutral position at this time, and there is leakage inside the solenoid valve. The front wheel angle change rate (front wheel speed) when the PWM is 50% and the front wheel turns left is defined as the left turn leakage speed threshold; if the front wheel is observed to turn right, the angle change rate (front wheel speed) at this time is defined as the right turn leakage speed threshold. The front wheel angle change rate in the field test is determined by dividing the front wheel angle difference at adjacent moments by the time interval at adjacent moments.

[0045] Step 2: Perform a solenoid valve leakage test on the agricultural machinery in operation. During the test, collect the front wheel angle data of the agricultural machinery in real time at a set time interval to obtain the angle data corresponding to multiple collection moments, and then calculate the front wheel angle change rate between adjacent collection moments;

[0046] As a preferred solution of this embodiment, the time interval is set to 10 ms, that is, the front wheel angle data of the agricultural machine is collected every 10 seconds.

[0047] Preferably, the front wheel turning angle change rate between adjacent collection moments is determined by the following formula:

[0048] Y=(θ (i+1) -θ (i) ) / △ t

[0049] In the formula,

[0050] Y is the rate of change of the front wheel turning angle;

[0051] θ (i+1) is the front wheel steering angle data collected at the i+1th sampling time, in degrees, where i is a positive integer;

[0052] θ (i) is the front wheel steering angle data collected at the i-th sampling moment, in degrees;

[0053] △ t is the set time interval in ms.

[0054] Step 3: Determine whether there is leakage in the solenoid valve according to whether the front wheel of the agricultural machine continues to rotate when the PWM duty cycle sent by the controller is 50%;

[0055] If the front wheel of the agricultural machine does not continue to rotate, it is determined that there is no leakage in the solenoid valve;

[0056] If the front wheel of the agricultural machinery continues to rotate, it is determined that the solenoid valve is leaking, and internal leakage treatment is performed according to the set leakage treatment strategy, including:

[0057] If the front wheel of the agricultural machinery continues to turn left and the current front wheel angle change rate is greater than the left turn leakage speed threshold determined in step 1, it is determined to be a left turn leakage, and the PWM duty cycle is adjusted to 0.5-deltaPWM; until the valve core returns to the mechanical middle position and the PWM duty cycle is restored to 50%.

[0058] If the front wheel of the agricultural machinery continues to turn right and the current front wheel angle change rate is less than the right turn leakage speed threshold determined in step 1, it is determined to be right turn leakage, and the PWM duty cycle is adjusted to 0.5+deltaPWM. This makes the voltage difference between the two sides of the electromagnetic coil of the solenoid valve, so that the solenoid valve control valve core is offset in the opposite direction until the valve core returns to the mechanical neutral position, and the PWM duty cycle is restored to 50%.

[0059] Among them, deltaPWM is the optimal PWM duty cycle change that can make the control valve core return to the mechanical neutral position when the solenoid valve control valve core leaks. The PWM duty cycle sent by the controller will eventually drive the solenoid coil of the solenoid valve in the form of voltage differential pressure. For example, the solenoid valve power supply voltage is 12V. When the PWM duty cycle is equal to 50%, the voltages obtained by the left and right sides of the solenoid coil are 6V respectively, and the voltage differential pressure is 0. The solenoid coil will not attract the solenoid valve core; when the PWM duty cycle is not equal to 50%, a voltage differential pressure will be generated on both sides of the solenoid coil, and the voltage differential pressure will form a magnetic field inside the solenoid valve. The solenoid coil will attract the solenoid valve core at different proportions and different rates according to the sign and size of the voltage differential pressure, thereby controlling the flow direction and flow rate of the hydraulic oil. Therefore, it is necessary to dynamically determine the optimal PWM duty cycle change that meets the current working conditions and can make the control valve core return to the mechanical neutral position, so that the PWM duty cycle can be restored to 50%.

[0060] As a preferred solution of this embodiment, deltaPWM is determined by the following formula:

[0061]

[0062] In the formula,

[0063] deltaPWM is the change in PWM duty cycle;

[0064] Y(t) is the front wheel speed corresponding to the t-th sampling time point, in deg / s;

[0065] K1 is the proportional gain coefficient;

[0066] K2 is the integral gain coefficient;

[0067] K3 is the differential gain coefficient.

[0068] In actual operation, a PID controller storing a PID algorithm can be used to complete the above operation, wherein the proportional gain coefficient K1, the integral gain coefficient K2 and the differential gain coefficient K3 are all empirical values, and K2=0.4K1, K3=0.2K1.

[0069] In this embodiment, K1=1, K2=0.4, K3=0.2.

[0070] Figure 2 This is the trend of PWM and front wheel angle changes when the solenoid valve is leaking. As can be seen from the upper figure, the steering action is completed at 4.8s, when the PWM duty cycle is 0.5, that is, when the controller has no steering command, the solenoid valve core is in the mechanical middle position. However, as can be seen from the lower figure, the front wheel angle still changes at this time, that is, the front wheel is still turning, indicating that the solenoid valve is leaking.

[0071] The change trend of the front wheel turning angle after the leakage treatment by the method of the present invention is as follows: Figure 3 As shown. Figure 3 It can be seen from the above figure that after the steering action is completed at 6 seconds, the method of the present invention is executed, deltaPWM=-0.1, that is, the PWM duty cycle is 0.4, and then the PWM duty cycle is restored to 0.5, that is, when the controller does not issue a steering command, the solenoid valve core is located in the mechanical middle position, and at the same time, the front wheel steering angle does not continue to change, indicating that after the leakage treatment is performed using the method of the present invention, the front wheel no longer rotates, and the leakage phenomenon of the solenoid valve is improved.

[0072] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for treating internal leakage of a solenoid valve for agricultural machinery, characterized in that: The following steps are involved: Step 1: Determine the left-turn leakage speed threshold and the right-turn leakage speed threshold of the agricultural machinery through field tests; Step 2: Perform a solenoid valve leakage test on the agricultural machinery in operation. During the test, collect the front wheel angle data of the agricultural machinery in real time at a set time interval to obtain the angle data corresponding to multiple collection moments, and then calculate the front wheel angle change rate between adjacent collection moments; Step 3: Determine whether there is leakage in the solenoid valve according to whether the front wheel of the agricultural machine continues to rotate when the PWM duty cycle sent by the controller is 50%; If the front wheel of the agricultural machine does not continue to rotate, it is determined that there is no leakage in the solenoid valve; If the front wheel of the agricultural machinery continues to rotate, it is determined that the solenoid valve is leaking, and internal leakage treatment is performed according to the set leakage treatment strategy, including: If the front wheel of the agricultural machinery continues to turn left and the current front wheel angle change rate is greater than the left turn leakage speed threshold determined in step 1, it is determined to be a left turn leakage, and the PWM duty cycle is adjusted to 0.5-deltaPWM; If the front wheel of the agricultural machinery continues to turn right and the current front wheel angle change rate is less than the right turn leakage speed threshold determined in step 1, it is determined to be a right turn leakage, and the PWM duty cycle is adjusted to 0.5+deltaPWM.

2. The method for treating internal liquid leakage of an agricultural machinery solenoid valve according to claim 1, characterized in that: The time interval set in step 2 is 10ms.

3. The method for treating internal liquid leakage of a solenoid valve for agricultural machinery according to claim 1, characterized in that: The front wheel turning angle change rate between adjacent collection moments in step 2 is determined by the following formula: Y=(θ (i+1) -θ (i) ) / △ t In the formula, Y is the rate of change of the front wheel turning angle; θ (i+1) is the front wheel steering angle data collected at the i+1th sampling time, in degrees, where i is a positive integer; θ (i) is the front wheel steering angle data collected at the i-th sampling moment, in degrees; △ t is the set time interval in ms.

4. The method for treating internal liquid leakage of a solenoid valve for agricultural machinery according to claim 1, characterized in that: △ PWM is determined by the following formula: In the formula, deltaPWM is the change in PWM duty cycle; Y(t) is the front wheel speed corresponding to the t-th sampling time point, in deg / s; K1 is the proportional gain coefficient; K2 is the integral gain coefficient; K3 is the differential gain coefficient.

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