Forklift gantry proportional valve control method and system

Abstract

The invention discloses a forklift portal proportional valve control method and system, and relates to the technical field of forklifts.The forklift portal proportional valve control method comprises the steps that a portal acts on the basis of a tilting target current needing to be achieved during forward tilting or backward tilting, and the target control current of a forward tilting or backward tilting proportional valve is calculated; the forward inclination maximum angle value and the backward inclination maximum angle value of the portal frame after forward inclination or backward inclination in place are collected; when the current portal frame is in the inclination process, the real-time inclination angle of forward inclination or backward inclination of the portal frame and the feedback current of the proportional valve are collected, and the real-time internal resistance value of the forward inclination or backward inclination proportional valve is calculated according to the real-time inclination angle and the feedback current of the proportional valve in combination with the target control current of the proportional valve; based on the target control current, the real-time internal resistance value, the rated resistance value, the proportional valve power supply voltage and the buffer current, the square wave duty ratio controlled and output by a forward-tilting or backward-tilting proportional valve is calculated, and the forward-tilting or backward-tilting proportional valve controls the portal frame to tilt based on the square wave duty ratio; according to the proportional valve control method and system, the accuracy and comfort of forklift portal frame inclination control are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of forklifts, and in particular, to a control method and system for a forklift mast proportional valve. Background Art

[0002] During the operation of a forklift, it is necessary to perform the forward or backward tilt operation of the mast to control the picking and placing of goods. The forklift performs the forward and backward tilt actions through the forward or backward tilt proportional valve. In the actual operation process of the driver, the control of the proportional valve is often affected by various factors such as the change of the power supply voltage at the valve end, the temperature and internal resistance change of the proportional valve, resulting in a large error in the control angle. The driver's operation comfort is relatively low, and there are potential safety hazards.

[0003] In the existing forklift technology, there is still a lack of precise control technology for the forward and backward tilt proportional valve of the forklift mast, and no measures are taken to reduce or eliminate the error of the forward or backward tilt control of the forklift mast proportional valve, which not only brings a very bad operation experience to the forklift operator, but also causes potential safety hazards due to the tilt angle error during the picking and placing of goods. Summary of the Invention

[0004] Based on the technical problems existing in the background art, the present invention proposes a control method and system for a forklift mast proportional valve, which improves the accuracy and comfort of the forklift mast tilt control.

[0005] A control method for a forklift mast proportional valve proposed by the present invention includes:

[0006] The mast acts based on the target tilt current required when tilting forward or backward, calculates the target control current of the forward or backward tilt proportional valve, and collects the maximum forward tilt angle value and the maximum backward tilt angle value after the mast tilts forward or backward in place;

[0007] When the current mast is in the tilting process, collect the real-time tilt angle of the mast tilting forward or backward and the feedback current of the proportional valve, and calculate the real-time internal resistance value of the forward or backward tilt proportional valve based on the combination of the target control current of the proportional valve;

[0008] Based on the target control current, the real-time internal resistance value, the rated resistance value, the power supply voltage of the proportional valve, and the buffer current, calculate the duty cycle of the square wave output by the forward or backward tilt proportional valve control, and the forward or backward tilt proportional valve controls the mast tilt based on the duty cycle of the square wave.

[0009] Further, the calculation formula of the target control current target i is as follows:

[0010]

[0011] wherein, in prince is the tilt thumb switch signal, is the minimum tilt thumb switch signal, ioutmax is the rated maximum current value output by the proportional valve, iout min is the minimum current value measured for the proportional valve to control the mast tilting action.

[0012] Furthermore, the proportional valve feedback current is specifically:

[0013] The proportional valve controls the mast to perform forward or backward tilting actions through the forward or backward tilting target control current;

[0014] The current value generated during the action execution of the proportional valve is used as the proportional valve feedback current.

[0015] Furthermore, when the absolute value of (target i -back i ) is less than the limited parameter current variable i ltd , the calculation formula of the real-time internal resistance relality res is as follows:

[0016]

[0017] where, rated res is the rated resistance value of the proportional valve, back i is the proportional valve feedback current value, V in is the supply voltage of the proportional valve, iout max is the rated maximum current value output by the proportional valve, target i is the target control current, and * represents multiplication.

[0018] Furthermore, in the calculation of the square wave duty cycle controlled by the proportional valve, when the mast tilts forward or backward, when the target control current target i is less than the buffer current iout buffer for the proportional valve to control the mast, the calculation formula of the square wave duty cycle is as follows:

[0019]

[0020] where, target i is the target control current, rated res is the rated resistance value of the proportional valve, V in is the supply voltage value of the proportional valve, and * represents multiplication.

[0021] Furthermore, when the mast tilts forward, when the target control current of the mast target i is greater than or equal to the buffer current iout buffer for the proportional valve to control the mast, and the maximum forward tilt angle value The difference between the real-time tilt angle Angle collected by the mast inclination sensor In is greater than the buffer angle value buffer angle ;

[0022] Or when the mast is tilted backward, the target control current target i is greater than or equal to the buffer current iout of the proportional valve controlling the mast buffer , and the maximum backward tilt angle value The difference from the real-time tilt angle Angle collected by the mast inclination sensor In is greater than the buffer angle value buffer angle ;

[0023] The square wave duty cycle The calculation formula is as follows:

[0024]

[0025] Among them, relality res is the real-time internal resistance.

[0026] Furthermore, when the mast is tilted forward, the target control current target of the mast i is greater than or equal to the buffer current iout of the proportional valve controlling the mast buffer , and the maximum forward tilt angle value The difference from the real-time tilt angle Angle collected by the mast inclination sensor In is less than or equal to the buffer angle value buffer angle ;

[0027] Or, when the mast is tilted backward, the target control current target of the mast i is greater than the buffer angle value buffer angle , and the maximum backward tilt angle value The difference from the real-time tilt angle Angle collected by the mast inclination sensor In is less than or equal to the buffer angle value buffer angle ;

[0028] The square wave duty cycle The calculation formula is as follows:

[0029]

[0030] Among them, iout buffer is the proportional valve buffer current, and relality res is the real-time internal resistance.

[0031] A forklift mast proportional valve control system includes a proportional valve control unit, a proportional valve power supply voltage module, a mast inclination sensor, a mast calibration switch, a thumb switch, and a proportional valve;

[0032] The proportional valve power supply voltage module is used to feedback the power supply voltage of the proportional valve;

[0033] The mast inclination sensor is used to obtain the real-time inclination angle of the mast when it tilts forward or backward;

[0034] The mast calibration switch is used to calibrate the maximum and minimum values of the mast inclination angle;

[0035] The thumb switch is used to represent the current value corresponding to the forklift driver pressing the forward tilt thumb switch or the backward tilt thumb switch, that is, the target control current of the forward tilt or backward tilt proportional valve;

[0036] The forward tilt or backward tilt proportional valve controls the forward tilt or backward tilt action of the mast and feedbacks the proportional valve feedback current to the proportional valve control unit;

[0037] The proportional valve control unit is used to obtain the feedback data of the proportional valve power supply voltage module, the mast inclination sensor, the mast calibration switch, and the thumb switch signal, and calculate the real-time internal resistance value of the forward tilt or backward tilt proportional valve based on this. At the same time, based on the target control current, the real-time internal resistance value, the rated resistance value, the proportional valve power supply voltage, and the buffer current, calculate the square wave duty ratio output by the forward tilt or backward tilt proportional valve control;

[0038] The forward tilt or backward tilt proportional valve controls the mast tilt based on the square wave duty ratio.

[0039] Furthermore, the proportional valve feedback current is specifically:

[0040] The proportional valve controls the forward tilt or backward tilt action of the mast through the forward tilt or backward tilt target control current;

[0041] The current value generated during the action execution of the proportional valve is used as the proportional valve feedback current.

[0042] Furthermore, when the absolute value of (target i -back i ) is less than the limited parameter current variable i ltd , the calculation formula of the real-time internal resistance relality res is as follows:

[0043]

[0044] Among them, rated res is the rated resistance value of the proportional valve, back i is the proportional valve feedback current value, V in is the proportional valve power supply voltage, ioutmax is the rated maximum current value output by the proportional valve, target i is the target control current, and * represents multiplication.

[0045] The advantages of a forklift mast proportional valve control method and system provided by the present invention are as follows: The proportional valve control method solves the control error caused by various factors such as the change of the valve-end power supply voltage, the change of the proportional valve temperature and internal resistance during the use of the proportional valve for the forklift mast, improves the accuracy and comfort of the forklift mast tilt control, and solves the practical problem of the proportional valve in the forklift mast controller system. Brief Description of the Drawings

[0046] Figure 1 is a schematic flow chart of the control method;

[0047] Figure 2 is a structural block diagram of the control system;

[0048] Figure 3 is a curve graph showing the relationship between the target control current and the front and rear tilt thumb switch signal amounts, where the coordinates of points A and B are known. Detailed Embodiment

[0049] Next, the technical solution of the present invention will be described in detail through specific embodiments. Many specific details are set forth in the following description in order to fully understand the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0050] As Figures 1 to 3 shown, a forklift mast proportional valve control method proposed by the present invention includes:

[0051] The mast acts based on the tilt target current to be achieved during forward or backward tilt, calculates the target control current of the forward or backward tilt proportional valve, and collects the maximum forward tilt angle value and the maximum backward tilt angle value after the mast is in place for forward or backward tilt;

[0052] When the current mast is in the tilt process, collect the real-time tilt angle of the mast during forward or backward tilt and the proportional valve feedback current, and calculate the real-time internal resistance value of the forward or backward tilt proportional valve based on the target control current of the proportional valve;

[0053] Based on the target control current, the real-time internal resistance value, the rated resistance value, the proportional valve supply voltage, and the buffer current, calculate the duty cycle of the square wave output by the forward or backward tilt proportional valve control. The forward or backward tilt proportional valve controls the mast tilt based on the duty cycle of the square wave.

[0054] In this embodiment, the proportional valve control unit collects the system logic control signal, and the forklift mast tilt sensor collects the real-time tilt angle of the forklift mast when it tilts forward or backward; the forward tilt thumb switch or the backward tilt thumb switch respectively collects the target control current that the driver needs to reach when performing the forward tilt or backward tilt action; by collecting the feedback current of the forward tilt or backward tilt proportional valve, the difference between the actual forward tilt or backward tilt current of the mast (i.e., the proportional valve feedback current) and the target control current of the forward tilt or backward tilt proportional valve that needs to be reached is further calculated; further combined with the proportional valve supply voltage value, the forklift mast tilt control is realized through the proportional valve control method; in this embodiment, the proportional valve control method solves the control error caused by various factors such as the change of the valve end supply voltage, the temperature and internal resistance of the proportional valve when using the proportional valve to control the forklift mast, improves the accuracy and comfort of the forklift mast tilt control, and solves the practical problem of the proportional valve in the forklift mast controller system.

[0055] In this embodiment, the implementation of the forklift mast proportional valve control method relies on the forklift mast proportional valve control system, as Figure 2 shown, this system specifically includes a proportional valve control unit, a proportional valve supply voltage module, a mast inclination sensor, a mast calibration switch, a thumb switch, and a proportional valve;

[0056] The proportional valve supply voltage module is used to feedback the supply voltage of the proportional valve;

[0057] The mast inclination sensor is used to obtain the real-time tilt angle of the mast when it tilts forward or backward;

[0058] The mast calibration switch is used to calibrate the maximum and minimum values of the mast tilt angle;

[0059] The thumb switch is used to represent the current value corresponding to the driver pressing the forward tilt thumb switch or the backward tilt thumb switch, that is, the target control current of the forward tilt or backward tilt proportional valve; the forward tilt or backward tilt proportional valve controls the forward tilt or backward tilt action of the mast and feeds back the proportional valve feedback current to the proportional valve control unit; the proportional valve control unit is used to obtain the feedback data of the proportional valve supply voltage module, the mast inclination sensor, the mast calibration switch, and the thumb switch signal, and calculate the real-time internal resistance value of the forward tilt or backward tilt proportional valve based on this, and at the same time calculate the square wave duty ratio of the forward tilt or backward tilt proportional valve control output based on the target control current, the real-time internal resistance value, the rated resistance value, the proportional valve supply voltage, and the buffer current; the forward tilt or backward tilt proportional valve controls the mast tilt based on the square wave duty ratio.

[0060] In this embodiment, in order to eliminate the error of the proportional valve control output caused by various factors such as the change of the proportional valve end voltage, the temperature and internal resistance of the proportional valve, it is necessary to calculate the duty ratio of the proportional valve control output in combination with relevant parameters. The implementation steps of the proportional valve control method are as follows:

[0061] S1: Define variables to store the values of the influencing factors;

[0062] During the process of calculating the duty cycle output control of the tilt forward or backward proportional valve, there are multiple influencing factors. For the convenience of calculation, first define some quantities: the rated resistance value of the proportional valve is rated res and the rated maximum current value iout output by the proportional valve max the minimum current value iout measured for the proportional valve to control the mast tilting action min the buffer current of the proportional valve is iout buffer the forward and backward tilt buffer angle value is buffer angle the limited parameter current variable is i ltd the supply voltage value of the proportional valve is V in the real-time tilt angle collected by the mast inclination sensor is Angle In the maximum forward tilt angle value is the maximum backward tilt angle value is the real-time internal resistance value of the tilt forward or backward proportional valve is relality res the target control current value variable is target i and the feedback current value of the tilt forward or backward proportional valve is back i the control output duty cycle value variable is

[0063] S2: The proportional valve control unit combines the rated maximum current value iout output by the proportional valve max the minimum current value iout for the proportional valve to control the mast tilting action min and the rated resistance value rated of the proportional valve res to calculate and determine the limited parameter current variable i ltd and its calculation formula is as follows:

[0064]

[0065] S3: The proportional valve control unit collects the maximum forward tilt angle value and the maximum backward tilt angle value after the mast tilts forward or backward in place through the mast calibration switch and the mast inclination sensor;

[0066] Specifically, close the mast calibration switch and operate the forward tilt thumb switch signal to the maximum value. At this time, the proportional valve control unit collects the forward tilt signal in of the forward tilt thumb switch prince and the proportional valve control unit controls the forward tilt proportional valve to output a current of the rated maximum value iout min to perform the mast forward tilt action. When the mast tilts forward in place, the proportional valve control unit collects the maximum forward tilt angle value of the mast inclination sensor at this time and stores it in the inclination variable. The proportional valve control unit will The value is saved in the external FLASH and will not be lost after power-off and restart.

[0067] Specifically, after the operation, tilt the thumb switch signal to the maximum value. At this time, the proportional valve control unit collects the backward tilt signal of the thumb switch in prince , and controls the output current of the backward tilt proportional valve to the rated maximum value iout max , and performs the mast backward tilt action. When the mast backward tilt is in place, the proportional valve control unit collects the maximum backward tilt angle value of the mast tilt sensor at this time and stores it in the tilt variable. The proportional valve control unit will The value is saved in the external FLASH and will not be lost after power-off and restart.

[0068] S4: The proportional valve control unit combines the forward tilt thumb switch signal in_price and calculates the target control current target of the forward tilt proportional valve according to the curve change rule shown in the appendix Figure 3 based on the coordinate values of points A and B i . The calculation formula is as follows:

[0069]

[0070] where in prince is the tilt thumb switch signal, is the minimum tilt thumb switch signal.

[0071] S5: During the operation of the forward tilt and backward tilt proportional valves, the proportional valve control unit collects the proportional valve supply voltage value V in , the real-time tilt angle Angle collected by the mast tilt sensor In , the feedback current bacl of the forward tilt or backward tilt proportional valve i . At the same time, combined with the rated resistance value rated of the forward tilt or backward tilt proportional valve res , the rated maximum current value iout max , the minimum current value iout for setting the proportional valve to control the mast tilt action min , the target control current target calculated in step S4 i , calculates the real-time internal resistance relality res . The specific calculation formula is as follows:

[0072]

[0073] S6: The proportional valve combines the target control current target of the forward tilt or backward tilt proportional valve calculated in step S4 i , the real-time internal resistance relality calculated in step S5 res , and the proportional valve supply voltage value V in, the minimum current value iout for measuring the proportional valve to control the mast tilt action min , the maximum forward tilt angle value the maximum backward tilt angle value the buffer angle value buffer angle , the buffer current value iout buffer , calculate the duty cycle of the output control square wave of the forward or backward tilt proportional valve

[0074] When calculating the duty cycle of the square wave Among them, according to the mast tilt action, tilt angle, control current, etc., set the following three calculation methods, specifically:

[0075] (1) When the mast tilts forward or backward, the target control current target i is less than the buffer current iout of the proportional valve to control the mast buffer , the duty cycle of the square wave The calculation formula is as follows:

[0076]

[0077] (2) The target control current target of the mast is satisfied i is greater than or equal to the buffer current iout of the proportional valve to control the mast buffer , and the maximum forward tilt angle value and the difference between the real-time tilt angle Angle collected by the mast tilt sensor In is greater than the buffer angle value buffer angle ;

[0078] Or when the mast tilts backward, the target control current target is satisfied i is greater than or equal to the buffer current iont of the proportional valve to control the mast buffer , and the maximum backward tilt angle value and the difference between the real-time tilt angle Angle collected by the mast tilt sensor In is greater than the buffer angle value buffer angle ;

[0079] The duty cycle of the square wave The calculation formula is as follows:

[0080]

[0081] (3) The target control current target of the mast is satisfied i is greater than or equal to the buffer current iout of the proportional valve to control the mast buffer , and the maximum forward tilt angle value and the real-time tilt angle Angle collected by the mast tilt sensorIn The difference is less than or equal to the buffer angle value buffer angle When;

[0082] Or, when the mast tilts backward, the target control current target of the mast is satisfied i Both are greater than the buffer angle value buffer angle And the maximum backward tilt angle value The difference from the real-time tilt angle Angle collected by the mast inclination sensor In Is less than or equal to the buffer angle value buffer angle When;

[0083] Square wave duty cycle The calculation formula is as follows:

[0084]

[0085] Through the above proportional valve control method, combining the real-time inclination angle, maximum inclination angle, power supply voltage and real-time current value of the mast, etc., eliminates the proportional valve tilt angle output control error caused by various factors such as the change of the proportional valve terminal voltage, the temperature of the proportional valve and the change of the internal resistance, greatly improves the driver's operation comfort, and reduces the potential safety risks in the forward and backward tilt operations of the mast.

[0086] As mentioned above, it is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and should be covered by the protection scope of the present invention.

Claims

1. A forklift mast proportional valve control method, characterized in that: include: The gantry moves based on the target tilt current that needs to be achieved when tilting forward or backward, calculates the target control current of the forward or backward proportional valve, and collects the maximum forward tilt angle value and the maximum backward tilt angle value after the gantry tilts forward or backward in place; When the gantry is in the process of tilting, the real-time tilt angle of the gantry forward or backward and the proportional valve feedback current are collected, and the real-time internal resistance value of the forward or backward proportional valve is calculated based on the proportional valve target control current; The square wave duty cycle of the forward or backward tilt proportional valve control output is calculated based on the target control current, the real-time internal resistance value, the rated resistance value, the proportional valve supply voltage and the buffer current. The forward or backward tilt proportional valve controls the gantry tilt based on the square wave duty cycle.

2. The forklift mast proportional valve control method according to claim 1, characterized in that: Target control current target i The calculation formula is as follows: Among them, prince For the thumb switch signal, is the minimum tilt thumb switch signal, iout max is the rated maximum current value of the proportional valve output, iout min It is the minimum current value for measuring the proportional valve controlling the gantry tilt action.

3. The forklift mast proportional valve control method according to claim 1, characterized in that: The proportional valve feedback current is specifically: The proportional valve controls the gantry to perform forward or backward tilting action through the forward or backward tilting target control current; The current value generated during the proportional valve execution process is used as the proportional valve feedback current.

4. The forklift mast proportional valve control method according to claim 1, characterized in that: When (target i -back i ) is less than the absolute value of the limiting parameter current variable i ltd When the real-time internal resistance is res The calculation formula is as follows: Among them, rated res is the rated resistance value of the proportional valve, back i is the proportional valve feedback current value, V in Supply voltage for proportional valve, iout max The rated maximum current value of the proportional valve output, target i is the target control current, and * indicates the product.

5. The forklift mast proportional valve control method according to claim 1, characterized in that: In the calculation of the square wave duty cycle of the proportional valve control output, when the gantry tilts forward or backward, the target control current target is met. i Less than the buffer current iout of the proportional valve control gantry buffer , square wave duty cycle The calculation formula is as follows: Among them, target i is the target control current, rated res is the rated resistance value of the proportional valve, V in It is the power supply voltage value of the proportional valve, and * indicates the product.

6. The forklift mast proportional valve control method according to claim 5, characterized in that: When the gantry tilts forward, the gantry target control current target is met i Greater than or equal to the buffer current iout of the proportional valve control gantry buffer , and the maximum forward tilt angle Real-time tilt angle Angle collected by the gantry tilt sensor In The difference is greater than the buffer angle value buffer angle ; Or when the gantry tilts backward, the target control current target is met i Greater than or equal to the buffer current iout of the proportional valve control gantry buffer , and the maximum tilt angle Real-time tilt angle Angle collected by the gantry tilt sensor In The difference is greater than the buffer angle value buffer angle ; Square wave duty cycle The calculation formula is as follows: Among them, relality res It is the real-time internal resistance.

7. The forklift mast proportional valve control method according to claim 5, characterized in that: When the gantry tilts forward, the gantry target control current target is met i Greater than or equal to the buffer current iout of the proportional valve control gantry buffer , and the maximum forward tilt angle Real-time tilt angle Angle collected by the gantry tilt sensor In The difference is less than or equal to the buffer angle value buffer angle hour; Or, when the gantry tilts backward, the gantry target control current target is met i Both are greater than the buffer angle value buffer angle , and the maximum tilt angle Real-time tilt angle Angle collected by the gantry tilt sensor In The difference is less than or equal to the buffer angle value buffer angle hour; Square wave duty cycle The calculation formula is as follows: Among them, iout buffer Buffer current for proportional valve, relality res It is the real-time internal resistance.

8. A forklift mast proportional valve control system, characterized in that: It includes a proportional valve control unit, a proportional valve power supply voltage module, a mast inclination sensor, a mast calibration switch, a thumb switch, and a proportional valve; The proportional valve power supply voltage module is used to feed back the power supply voltage of the proportional valve; The mast inclination sensor is used to obtain the real-time inclination angle of the mast when the mast is tilted forward or backward; The mast calibration switch is used to calibrate the maximum mast tilt angle and the minimum mast tilt angle; The thumb switch is used to indicate the current value corresponding to the forklift driver pressing the forward tilt thumb switch or the backward tilt thumb switch, that is, the target control current of the forward tilt or backward tilt proportional valve; The forward tilt or backward tilt proportional valve controls the mast forward tilt or backward tilt and feeds back proportional valve feedback current to the proportional valve control unit; The proportional valve control unit is used to obtain the feedback data of the proportional valve power supply voltage module, the mast inclination sensor, the mast calibration switch, and the thumb switch signal, and calculate the real-time internal resistance value of the forward or backward proportional valve based on the data, and at the same time calculate the square wave duty cycle of the forward or backward proportional valve control output based on the target control current, the real-time internal resistance value, the rated resistance value, the proportional valve power supply voltage, and the buffer current; The forward or backward tilt proportional valve controls the mast tilt based on a square wave duty cycle.

9. The forklift mast proportional valve control system according to claim 8, characterized in that: The proportional valve feedback current is specifically: The proportional valve controls the gantry to perform forward or backward tilting action through the forward or backward tilting target control current; The current value generated during the proportional valve execution process is used as the proportional valve feedback current.

10. The forklift mast proportional valve control system according to claim 8, characterized in that: When (target i -back i ) is less than the absolute value of the limiting parameter current variable i ltd When the real-time internal resistance is res The calculation formula is as follows: Among them, rated res is the rated resistance value of the proportional valve, back i is the proportional valve feedback current value, V in Supply voltage for proportional valve, iout max The rated maximum current value of the proportional valve output, target i is the target control current, and * indicates the product.

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