CN-121974274-A - Lifting control method and device of electric forklift

CN121974274ACN 121974274 ACN121974274 ACN 121974274ACN-121974274-A

Abstract

The invention discloses a lifting control method and device of an electric forklift. The method comprises the steps of determining the current target rotating speed of the lifting motor according to the current voltage, the middle voltage, the first voltage, the second voltage, the maximum rotating speed of the lifting motor and the preset middle rotating speed after a vehicle leaves a factory, determining the current quadrature axis target current of the lifting motor according to the current target rotating speed of the lifting motor and the actual lifting rotating speed, and controlling the lifting motor to operate according to the current quadrature axis target current after the current voltage of the lifting potentiometer is larger than the first voltage and smaller than the second voltage and the lifting trigger signal is smaller than the second voltage. The technical scheme of the invention improves the lifting control of the electric forklift more accurately.

Inventors

LI YUHONG
ZHANG PINGHUA
MENG FANJI

Assignees

凡己科技(苏州）有限公司

Dates

Publication Date: 20260505
Application Date: 20260408

Claims (11)

1. The lifting control method of the electric forklift is characterized in that the electric forklift comprises a lifting motor, a lifting oil way, a lifting operation rod, a lifting potentiometer and a lifting switch, wherein one end of the lifting operation rod is connected with a valve core of a multi-way valve in the lifting oil way, one end of the lifting potentiometer is connected with the valve core of the multi-way valve, and the lifting switch comprises a travel switch; The method comprises the following steps: After the vehicle leaves the factory, in the current lifting motor rotating speed control period, if the current voltage of the lifting potentiometer is larger than the first voltage and smaller than or equal to the intermediate voltage, and the lifting switch sends out a lifting trigger signal, the current target rotating speed of the lifting motor is a preset intermediate rotating speed; After the vehicle leaves the factory, in a current lifting motor rotating speed control period, if the current voltage is larger than the intermediate voltage and smaller than the second voltage, and the lifting switch sends out a lifting trigger signal, determining a current target rotating speed of the lifting motor according to the current voltage, the intermediate voltage, the first voltage, the second voltage, the maximum rotating speed of the lifting motor and the preset intermediate rotating speed; Determining a current quadrature axis target current of the lifting motor according to the current target rotating speed and the actual lifting rotating speed of the lifting motor, and controlling the lifting motor to operate according to the current quadrature axis target current.
2. The method of claim 1, wherein said controlling operation of said lift motor in accordance with said current quadrature target current comprises: After the rotation speed of the lifting motor is stable, taking a preset rotation speed command as the current target rotation speed of the lifting motor, updating the current cross shaft target current according to the preset rotation speed command, and controlling the lifting motor to operate according to the updated current cross shaft target current until the lifting operation rod is released, wherein the preset condition is that the current cross shaft target current of the lifting motor is larger than the product of the preset cross shaft current and a preset heavy load threshold value, and the maintenance time of the current target rotation speed being larger than the preset heavy load rotation speed is longer than a first preset time period; and if the preset condition is not met, controlling the lifting motor to run according to the current quadrature axis target current until the lifting operation rod is released.
3. The method of claim 1, wherein prior to determining a present quadrature axis target current of the lift motor based on a present target rotational speed and an actual lift rotational speed of the lift motor, the method further comprises: If the current voltage of the lifting potentiometer is smaller than or equal to the first voltage, the current target rotating speed of the lifting motor is zero; if the current voltage of the lifting potentiometer is greater than or equal to the second voltage and the lifting switch sends out a lifting trigger signal, the current target rotating speed of the lifting motor is the maximum rotating speed of the lifting motor.
4. The method of claim 1, wherein after the vehicle leaves the factory, in a current lifting motor rotation speed control period, if the current voltage of the lifting potentiometer is greater than the first voltage and less than or equal to the intermediate voltage, and the lifting switch sends a lifting trigger signal, before the current target rotation speed of the lifting motor is the preset intermediate rotation speed, the method further comprises: Before the delivery of the vehicle, when the lifting operation rod is pushed, taking the voltage of the lifting potentiometer corresponding to the moment of receiving the lifting trigger signal as the first voltage, wherein the stroke of the lifting operation rod corresponding to the first voltage is zero; And determining the second voltage according to the voltage of the lifting potentiometer corresponding to the maximum stroke of the lifting operation rod, wherein the stroke of the lifting operation rod corresponding to the second voltage is 100%.
5. The method of claim 4, wherein after determining the second voltage from the voltage of the lifting potentiometer corresponding to when the stroke of the lifting lever is maximum, the method further comprises: And taking the product of the second voltage and a second preset proportionality coefficient as the intermediate voltage, wherein the second preset proportionality coefficient is larger than zero and smaller than or equal to 30%.
6. The method of claim 4, wherein determining the second voltage from the voltage of the lifting potentiometer corresponding to when the stroke of the lifting lever is maximum comprises: Taking the product of the voltage of the lifting potentiometer corresponding to the maximum stroke of the lifting operation rod and a first preset proportionality coefficient as the second voltage, wherein the first preset proportionality coefficient is larger than 100%.
7. The method of claim 1, wherein the electric fork-lift truck further comprises a travel motor, the method further comprising: When the actual running rotating speed of the running motor is larger than a first rotating speed threshold value, controlling the current target rotating speed of the lifting motor to be zero; when the actual running rotating speed of the running motor is smaller than or equal to a first rotating speed threshold value, the lifting switch sends out the lifting trigger signal again, and the voltage of the lifting potentiometer is larger than the first voltage, the current target rotating speed of the lifting motor is controlled to be not zero.
8. The method of claim 7, wherein before the actual walking speed of the walking motor is less than or equal to a first speed threshold, and the lift switch again sends the lift trigger signal, and the voltage of the lift potentiometer is greater than the first voltage, controlling the current target speed of the lift motor to be non-zero, the method further comprises: when the actual running rotating speed of the running motor is larger than a second rotating speed threshold and smaller than or equal to the first rotating speed threshold and the turning angle of the electric forklift is larger than a preset angle threshold, controlling the current target rotating speed of the lifting motor to be zero.
9. The method of claim 1, wherein the method further comprises, at a current lift motor speed control cycle after shipment of the vehicle: when the maintenance time length of the difference value of the current voltage less than the first voltage minus the first preset threshold value is longer than the second preset time length, a prompt message is sent; when the maintaining time period of the current voltage larger than the sum of the second voltage and a second preset threshold value is longer than the second preset time period, sending out prompt information; And when the current voltage is greater than or equal to the intermediate voltage and the lifting trigger signal of the lifting switch is not received, sending out prompt information.
10. The method of claim 1, wherein determining the current target rotational speed of the lift motor from the current voltage, the intermediate voltage, the first voltage, the second voltage, the maximum rotational speed of the lift motor, and the preset intermediate rotational speed comprises: and dividing the difference value of the current voltage minus the intermediate voltage by the difference value of the second voltage minus the first voltage, multiplying the difference value of the maximum rotating speed and the preset intermediate rotating speed, and adding the preset intermediate rotating speed to obtain the current target rotating speed.
11. The lifting control device of the electric forklift truck is characterized by being used for executing the lifting control method of the electric forklift truck, wherein the electric forklift truck comprises a lifting motor, a lifting oil path, a lifting operation rod, a lifting potentiometer and a lifting switch, one end of the lifting operation rod is connected with a valve core of a multi-way valve in the lifting oil path, one end of the lifting potentiometer is connected with the valve core of the multi-way valve, and the lifting switch comprises a travel switch; the lifting control device of the electric forklift comprises: the first target rotating speed determining module is used for determining the current target rotating speed of the lifting motor to be the preset middle rotating speed in the current lifting motor rotating speed control period after the vehicle leaves the factory if the current voltage of the lifting potentiometer is larger than the first voltage and smaller than or equal to the middle voltage and the lifting switch sends out a lifting trigger signal; The second target rotating speed determining module is used for determining the current target rotating speed of the lifting motor according to the current voltage, the intermediate voltage, the first voltage, the second voltage, the maximum rotating speed of the lifting motor and the preset intermediate rotating speed if the current voltage is larger than the intermediate voltage and smaller than the second voltage and the lifting switch sends out a lifting trigger signal in the current lifting motor rotating speed control period after the vehicle leaves the factory; The motor control module is used for determining the current intersecting axis target current of the lifting motor according to the current target rotating speed and the actual lifting rotating speed of the lifting motor, and controlling the lifting motor to operate according to the current intersecting axis target current.

Description

Lifting control method and device of electric forklift Technical Field The invention relates to the field of control of electric forklifts, in particular to a lifting control method and device of an electric forklifts. Background The lifting function of the electric forklift is an important function, and the lifting mechanism of the electric forklift can lift cargoes from the ground to the target height. The lifting mechanism is a hydraulic mechanism. The lifting mechanism can comprise a lifting motor (namely an oil pump motor), a valve core of a multi-way valve (a multi-way reversing valve) in a lifting oil way of the lifting mechanism is connected with a lifting operation rod, and a lifting potentiometer is connected with the valve core, and when a driver operates the lifting operation rod, the valve core is driven to move, so that the multi-way valve is opened, an oil cylinder can be used for feeding oil, and a piston rod in the oil cylinder can push a fork to lift. In the process of moving the valve core, the movable end of the lifting potentiometer is driven to move, so that the voltage of the lifting potentiometer changes, and the movement amount of the lifting operation rod can be determined according to the voltage of the lifting potentiometer, so that the rotation speed of the lifting motor can be controlled according to the voltage of the lifting potentiometer, and the rotation speed of the lifting motor is matched with the movement amount of the lifting operation rod. In the operation of the existing lifting motor, the rotating speed of the motor and the voltage of the lifting potentiometer are in linear relation, and the larger the voltage of the lifting potentiometer is, the larger the rotating speed of the motor is. However, when the voltage of the lifting potentiometer is smaller, if the rotating speed of the motor is too small, the oil is filled too slowly, the lifting speed is too slow, the lifting speed is not matched with the moving amount of the lifting operation rod, and the lifting control cannot be accurately performed. Disclosure of Invention The invention provides a lifting control method and device for an electric forklift, which solve the problem that the electric forklift cannot accurately perform lifting control. According to one aspect of the invention, the lifting control method of the electric forklift is provided, the electric forklift comprises a lifting motor, a lifting oil way, a lifting operation rod, a lifting potentiometer and a lifting switch, wherein one end of the lifting operation rod is connected with a valve core of a multi-way valve in the lifting oil way, one end of the lifting potentiometer is connected with the valve core of the multi-way valve, and the lifting switch comprises a travel switch; The method comprises the following steps: After the vehicle leaves the factory, in the current lifting motor rotating speed control period, if the current voltage of the lifting potentiometer is larger than the first voltage and smaller than or equal to the intermediate voltage, and the lifting switch sends out a lifting trigger signal, the current target rotating speed of the lifting motor is a preset intermediate rotating speed; After the vehicle leaves the factory, in a current lifting motor rotating speed control period, if the current voltage is larger than the intermediate voltage and smaller than the second voltage, and the lifting switch sends out a lifting trigger signal, determining a current target rotating speed of the lifting motor according to the current voltage, the intermediate voltage, the first voltage, the second voltage, the maximum rotating speed of the lifting motor and the preset intermediate rotating speed; Determining a current quadrature axis target current of the lifting motor according to the current target rotating speed and the actual lifting rotating speed of the lifting motor, and controlling the lifting motor to operate according to the current quadrature axis target current. Optionally, the controlling the lifting motor to operate according to the current quadrature axis target current includes: After the rotation speed of the lifting motor is stable, taking a preset rotation speed command as the current target rotation speed of the lifting motor, updating the current cross shaft target current according to the preset rotation speed command, and controlling the lifting motor to operate according to the updated current cross shaft target current until the lifting operation rod is released, wherein the preset condition is that the current cross shaft target current of the lifting motor is larger than the product of the preset cross shaft current and a preset heavy load threshold value, and the maintenance time of the current target rotation speed being larger than the preset heavy load rotation speed is longer than a first preset time period; and if the preset condition is not met, controlling the lifting motor to run according to the c