Electric stacker crane mast lifting control method and system

Abstract

The application discloses a kind of electric stacker gantry hoisting control method and system, it is related to industrial vehicle technical field;The system includes: hoisting cylinder, hydraulic oil tank, hydraulic pump, oil pump motor, solenoid valve, pressure sensor, proximity switch, inductive plate and controller;Proximity switch judges whether fork reaches gantry high position by detecting inductive plate position, reaches when controller cooperates control oil pump motor speed and solenoid valve opening, slows down gantry hoisting speed;Pressure sensor is provided with the preset value less than the overflow pressure of hydraulic system, when hoisting oil circuit oil pressure reaches the preset value, controller controls oil pump motor to stop, so that gantry is accurately parked at the highest position.The application effectively solves the problems of traditional stacker gantry hoisting inertia, gantry shaking and inaccurate positioning, improves operation safety and logistics turnover efficiency, and has simple structure and low modification cost.

Description

Technical Field

[0001] This invention relates to the field of industrial vehicles and warehousing and handling equipment, and in particular to a method and system for controlling the lifting of an electric stacker truck gantry. Background Technology

[0002] Electric stacker trucks are core cargo handling and stacking equipment in modern logistics and warehousing systems. Powered by batteries, they integrate walking drive, hydraulic lifting and safety electronic control systems. With advantages such as energy saving and environmental protection, flexible operation and high efficiency, they are widely used in manufacturing production lines, commercial distribution warehouses, e-commerce logistics centers and other scenarios, and can realize short-distance transfer of palletized goods and high-rise rack stacking operations.

[0003] As the warehousing and logistics industry continues to demand higher space utilization rates, the maximum lifting height of electric stacker truck masts has gradually increased from the traditional 3 meters to 6 meters or even higher. Simultaneously, to meet the demands of fast-paced logistics turnover, the industry generally improves operational efficiency by increasing mast lifting speed. However, this dual increase in lifting height and speed has made the shortcomings of traditional mast lifting control methods increasingly apparent. 1) Inertial impact and overshoot risk: When the forks carrying goods approach the top dead center of the mast at high speed, the huge inertia makes it difficult for traditional mechanical limit and hydraulic overflow brake to achieve instantaneous and smooth stopping. Overshoot and overshoot are very likely to occur, which will cause severe impact on the top structure of the mast. Long-term use will cause mast deformation, weld cracking and reduce the service life of the equipment. 2) Gantry swaying and safety hazards: A sudden stop after high-speed lifting will cause significant swaying of the gantry and the entire vehicle, which not only affects the stability of cargo stacking and poses a major safety risk of cargo slipping and injuring people, but also leads to driver fatigue and reduces operating comfort. 3) Low positioning accuracy and reduced operating efficiency: Under the traditional control method, the stop position error of the forks is large, and the driver needs to make repeated fine adjustments to align with the shelf, which significantly increases the single operation time and reduces the overall logistics turnover efficiency.

[0004] In summary, how to achieve smooth deceleration and precise stopping of the gantry during high-level lifting while ensuring the gantry lifting speed, thereby eliminating inertial impact and improving operational safety and positioning accuracy, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and system for controlling the lifting of an electric stacker truck gantry. Through a dual closed-loop control strategy of "proximity switch high-position pre-deceleration + pressure sensor precise stopping", it effectively solves the problems of inertial overshoot, gantry swaying, inaccurate positioning and significant safety hazards that exist in the lifting process of traditional electric stacker truck gantry.

[0006] The present invention adopts the following technical solution: On one hand, the present invention provides an electric stacker gantry lifting control system for electric stackers, which includes: lifting cylinder, hydraulic oil tank, hydraulic pump, oil pump motor, solenoid valve, pressure sensor, proximity switch, sensing plate and controller.

[0007] The lifting cylinder is used to drive the outer and inner masts of the stacker truck to perform lifting actions, and the return port of the lifting cylinder is connected to the hydraulic oil tank; the inlet of the hydraulic pump is connected to the hydraulic oil tank, the outlet of the hydraulic pump is connected to the solenoid valve, and the outlet of the solenoid valve is connected to the inlet of the lifting cylinder; the oil pump motor is connected to the hydraulic pump drive and is used to drive the hydraulic pump to operate.

[0008] The pressure sensor is connected to the lifting oil circuit and is used to detect the oil pressure in the lifting oil circuit in real time; the sensing plate is fixed on the inner gantry, and the proximity switch is arranged and installed on the outer gantry corresponding to the sensing plate; the oil pump motor, solenoid valve, proximity switch, and pressure sensor are all electrically connected to the controller.

[0009] The proximity switch is used to sense the position of the sensing plate and send a position sensing signal to the controller. The controller determines whether the forks have reached the high position of the mast based on the position sensing signal. When it is determined that the forks have reached the high position of the mast, the controller reduces the mast lifting speed by adjusting the speed of the oil pump motor and the opening of the hydraulic oil flow of the solenoid valve.

[0010] The pressure sensor is set with a preset pressure value, which is less than the overflow pressure of the hydraulic system. When the oil pressure in the lifting oil circuit reaches the preset pressure value, the pressure sensor sends a pressure trigger signal to the controller. After receiving the pressure trigger signal, the controller controls the oil pump motor to stop, so that the gantry stops lifting and stops at the highest position.

[0011] Furthermore, a check valve is provided between the solenoid valve and the inlet of the lifting cylinder, and the inlet of the check valve is connected to the outlet of the solenoid valve; the outlet of the check valve is divided into two paths, one path connecting to the inlet of the lifting cylinder and the other path connecting to the relief valve; the pressure sensor is installed on the connecting oil passage between the outlet of the check valve and the inlet of the lifting cylinder, and the outlet of the relief valve is connected to the hydraulic oil tank.

[0012] Furthermore, it also includes an upper buffer bracket, which is fixed to the edge of the upper crossbeam of the outer gantry, and the proximity switch is fixedly installed on the upper buffer bracket.

[0013] Furthermore, it also includes an integrated handle, which is mounted on the stacker truck's steering arm and electrically connected to the controller. The integrated handle is used to issue lifting operation commands to the controller, and the controller controls the oil pump motor and solenoid valve to work together according to the lifting operation commands to realize the lifting operation control of the forks.

[0014] Furthermore, it also includes a battery, which is connected to the power supply input terminal of the controller. The controller supplies power to the oil pump motor, solenoid valve, proximity switch and pressure sensor through an internal power supply circuit.

[0015] On the other hand, the present invention provides an electric stacker gantry lifting control method, applied to the electric stacker gantry lifting control system described in any one of the above-mentioned methods, comprising the following steps: When the stacker truck is performing gantry lifting operations, the proximity switch senses and detects the position of the sensing plate on the inner gantry in real time. When the sensing plate enters the sensing range of the proximity switch, the proximity switch outputs a position sensing signal to the controller.

[0016] The controller monitors in real time whether it receives a position sensing signal from the proximity switch. If no position sensing signal is received, the controller controls the oil pump motor and solenoid valve to work normally according to the preset instructions, and the mast lifts normally at the rated set speed. If a position sensing signal is received, it is determined that the forks have reached the mast high position, and the controller adjusts the mast lifting speed according to the preset control parameters, that is, the mast lifting speed is reduced.

[0017] After the gantry enters the low-speed lifting stage, the pressure sensor collects the oil pressure of the lifting oil circuit in real time and compares it with its own preset pressure value. If the oil pressure in the oil circuit does not reach the preset pressure value, the pressure sensor continues to detect the oil pressure, and the gantry continues to lift at a low speed. If the oil pressure in the oil circuit reaches the preset pressure value, the pressure sensor sends a pressure trigger signal to the controller.

[0018] After receiving the pressure trigger signal, the controller stops the oil pump motor and closes the solenoid valve, cutting off the hydraulic oil supply circuit of the lifting cylinder. The gantry immediately stops lifting and locks itself in the highest position.

[0019] Furthermore, the specific control method for reducing the gantry lifting speed is as follows: the controller reduces the opening of the solenoid valve to reduce the hydraulic oil flow rate in the lifting cylinder, and at the same time, the operating speed of the oil pump motor is reduced simultaneously. The two work together to achieve a smooth, uniform, and low-speed lifting of the gantry.

[0020] Furthermore, the specific method for gantry termination and lifting lock is as follows: the controller stops the oil pump motor and the solenoid valve is completely closed, disconnecting the hydraulic oil supply path between the lifting cylinder and the hydraulic pump, so that the lifting cylinder is locked, achieving precise positioning of the gantry and forks at rest.

[0021] In another aspect, the present invention provides an electric stacker truck equipped with the electric stacker truck gantry lifting control system described in any of the above claims.

[0022] Compared with the prior art, the present invention has the following beneficial effects: 1) Dual closed-loop control to completely solve the overshoot problem: This invention adopts a two-stage control strategy of "proximity switch pre-deceleration + pressure sensor precise shutdown". First, the proximity switch reduces the lifting speed in advance before the forks reach the high position, eliminating most of the motion inertia; then, the pressure sensor precisely triggers the shutdown when the mast reaches the mechanical top stop, avoiding the pressure shock when the traditional overflow valve overflows, and fundamentally eliminating the overshoot and over-rush phenomenon. 2) Improve operational safety and stability: Through smooth deceleration and soft stop control, the swaying amplitude of the gantry and the whole vehicle is significantly reduced, avoiding the safety risk of goods slipping due to swaying. At the same time, it reduces fatigue damage to the gantry structure and extends the service life of the equipment. 3) Improve positioning accuracy and work efficiency: Precise stop control keeps the fork stop position error within ±5mm, eliminating the need for the driver to repeatedly fine-tune the alignment. The time for a single stacking operation can be shortened by 15%-20%, greatly improving logistics turnover efficiency. 4) Simple structure and low modification cost: This invention only adds proximity switches, sensing plates and pressure sensors to the existing hydraulic system. It does not require large-scale modification of the main structure of the gantry, and is easy to promote and apply to existing products with low modification cost. Attached Figure Description

[0023] To better illustrate the implementation examples of this application, the accompanying drawings used in the implementation examples will be briefly described below. Obviously, the accompanying drawings used for the illustration below are only some implementation examples of this application. For those skilled in the art, other drawings can be obtained from these drawings without any creative effort.

[0024] Figure 1 This is a schematic diagram of the overall structure of the electric stacker truck described in an embodiment of the present invention; Figure 2 This is a partial structural schematic diagram of the electric stacker gantry described in an embodiment of the present invention; Figure 3 This is a control logic block diagram of the electric stacker gantry lifting control system described in an embodiment of the present invention; Figure 4 This is a flowchart illustrating the electric stacker gantry lifting control method according to an embodiment of the present invention; In the diagram: 1. Outer mast; 2. Inner mast; 3. Lifting cylinder; 4. Hydraulic oil tank; 5. Hydraulic pump; 6. Pump motor; 7. Solenoid valve; 8. Pressure sensor; 9. Proximity switch; 10. Sensing plate; 11. Controller; 12. Upper buffer bracket; 13. Upper crossbeam; 14. Forks. Detailed Implementation

[0025] The technical solutions in the embodiments of this application will be described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the protection scope of this application.

[0026] The core of this application is to provide a method and system for controlling the movement stability of an electric stacker truck mast, so as to solve the problem that the current electric stacker truck masts sway greatly during movement due to high speed, which can easily cause goods to slip off, affect the stability of the whole vehicle, and cause accidents.

[0027] To enable those skilled in the art to better understand the embodiments of this application, further detailed descriptions will be provided below in conjunction with the accompanying drawings and specific implementation details.

[0028] This invention provides an electric stacker gantry lifting control system, such as... Figures 1-3 As shown, it includes: lifting cylinder 3, hydraulic oil tank 4, hydraulic pump 5, oil pump motor 6, solenoid valve 7, pressure sensor 8, proximity switch 9, sensing plate 10, controller 11, upper buffer bracket 12, integrated handle and battery.

[0029] Solenoid valve 7: It is a basic component of automation used to control fluid. Functionally, the solenoid valve in this embodiment belongs to the category of directional control valve and speed regulating valve. In this embodiment, it is used to control the direction and speed of hydraulic oil and is a type of proportional directional solenoid valve.

[0030] Pressure sensor 8: is a detection device that converts the pressure signal applied by a fluid or solid into a measurable electrical signal; in this embodiment, the pressure sensor converts the sensed oil pressure into an electrical signal and transmits it to the controller 11.

[0031] Controller 11: This refers to a device that controls the voltage, current, and speed of a motor by changing the wiring of the main circuit or control circuit and changing the resistance value in the circuit according to user operation commands and in accordance with certain rules. It integrates signal logic processing, commutation control, electromagnetic brake drive, and protection logic such as overcurrent, overvoltage, undervoltage, and runaway prevention; it realizes the conversion and control of electrical control signals such as vehicle movement and lifting actions into mechanical power. In this implementation case, the controller is used to receive signals from proximity switches and pressure sensors, and transmit output commands and information according to the received signals and operator operations.

[0032] Oil pump motor 6: This is a dedicated drive device that provides power to hydraulic equipment. In this implementation case, it provides power to hydraulic pump 5, converting electrical energy into hydraulic energy to power the lifting and lowering of the forks. In this example, hydraulic pump 5 is a gear pump.

[0033] Proximity switch 9 is a sensor that can detect the position of an object without mechanical contact. It senses the approach of an object through principles such as electromagnetic induction and photoelectricity, and converts the sensed information into an electrical signal or other form of signal output to meet the requirements of information transmission, processing, display, recording, and control. In this embodiment, proximity switch 9 converts the sensed position information into an electrical signal and transmits it to controller 11.

[0034] Induction plate 10: It is a metal plate with no specific requirements for installation method and shape. In this embodiment, the mounting plate is used to provide the proximity switch with fork position information.

[0035] It should be noted that the placement of proximity switch 9 and sensor plate 10 is not specifically limited in this embodiment. It can be understood that the placement of proximity switch 9 and sensor plate 10 on the electric stacker truck is not restricted, and is not limited by any other factors. Figure 2 The structure shown in the figure constitutes a limitation on this implementation example.

[0036] The stacker mast includes an outer mast 1 and an inner mast 2. The outer mast 1 is a fixed support structure for the mast system. The inner mast 2 is nested inside the outer mast 1 and can slide up and down along the guide rail of the outer mast 1. The forks 14 are fixedly installed on the inner mast 2 and rise and fall synchronously with the inner mast 2. The lifting cylinder 3 is vertically installed between the outer mast 1 and the inner mast 2. The bottom end of its cylinder body is fixed to the bottom of the outer mast 1, and the top end of its piston rod is connected to the top of the inner mast 2. The lifting and lowering actions of the inner mast 2 and the forks 14 are achieved by extending and retracting the piston rod.

[0037] Hydraulic system components: Hydraulic oil tank 4 stores hydraulic oil. The inlet of hydraulic pump 5 is connected to hydraulic oil tank 4 via a suction pipe, and the outlet of hydraulic pump 5 is connected to the inlet of solenoid valve 7. Solenoid valve 7 is a proportional directional control valve, and its outlet is connected to the inlet of lifting cylinder 3 via a check valve. The return port of lifting cylinder 3 is connected to hydraulic oil tank 4 via a return pipe. The check valve prevents hydraulic oil backflow and ensures that lifting cylinder 3 will not descend on its own under load. The outlet of the check valve is divided into two paths: one path is connected to the inlet of lifting cylinder 3, and the other path is connected to the inlet of relief valve. The outlet of relief valve is connected to hydraulic oil tank 4. The relief valve serves as a system safety protection element, and its set pressure is the maximum working pressure of the hydraulic system (relief pressure). When the system oil pressure exceeds the relief pressure, the relief valve opens to relieve the load and protect the hydraulic system from damage.

[0038] Pressure sensor 8 is installed on the connecting oil passage between the oil outlet of the one-way valve and the oil inlet of the lifting cylinder 3 to detect the working oil pressure of the lifting oil circuit in real time; the signal output terminal of pressure sensor 8 is electrically connected to the signal input terminal of controller 11; the pressure sensor 8 has a preset trigger pressure value, which is less than the overflow pressure of the relief valve, and ensures that a stop signal is triggered before the relief valve is opened.

[0039] Position detection section: The sensing plate 10 is a rectangular metal plate, which is installed on the inner wall of the inner gantry 2 by welding or bolting. Its installation height corresponds to the position of the high-position deceleration point of the gantry. The proximity switch 9 is an inductive proximity switch, which is fixedly installed on the edge of the upper crossbeam 13 of the outer gantry 1 by the upper buffer bracket 12. The sensing head of the proximity switch 9 faces the inner gantry 2 and corresponds to the movement trajectory of the sensing plate 10. The signal output terminal of the proximity switch 9 is electrically connected to the signal input terminal of the controller 11. When the sensing plate 10 rises with the inner gantry 2 into the sensing range of the proximity switch 9, the proximity switch 9 is activated and sends a position sensing signal to the controller 11.

[0040] Control and Operation Section: Controller 11 is the core control unit of the vehicle, integrating functions such as signal processing, logic operation, motor drive and solenoid valve control; the integrated handle is installed on the rudder arm of the stacker truck, and has operation buttons such as lifting, lowering, forward and reverse. The signal output terminal of the integrated handle is electrically connected to the signal input terminal of controller 11, and is used to input the driver's operation commands to controller 11; the battery is the power source of the vehicle, and its positive and negative terminals are connected to the power supply input terminal of controller 11. Controller 11 supplies power to oil pump motor 6, solenoid valve 7, proximity switch 9, pressure sensor 8 and other electrical components through internal power supply circuit.

[0041] This invention also provides a method for controlling the lifting of an electric stacker truck gantry, such as... Figure 4 As shown, the specific working process of the electric stacker truck gantry lifting control system described above is as follows: During normal lifting phase: The operator issues a lifting operation command to the controller 11 via the integrated handle. Upon receiving the command, the controller 11 starts the oil pump motor 6 and operates it at the rated speed, while simultaneously controlling the solenoid valve 7 to open to the corresponding degree. Driven by the oil pump motor 6, the hydraulic pump 5 pressurizes the hydraulic oil in the hydraulic oil tank 4 and delivers it to the solenoid valve 7. The hydraulic oil enters the rodless chamber of the lifting cylinder 3 through the check valve, pushing the piston rod to extend and driving the inner mast 2 and forks 14 to rise at the rated speed. At this time, the sensing plate 10 has not yet entered the sensing range of the proximity switch 9, the controller 11 has not received the position sensing signal, and the mast maintains normal lifting speed.

[0042] High-position deceleration stage: When the inner mast 2 drives the sensing plate 10 to rise into the sensing range of the proximity switch 9, the proximity switch 9 immediately sends a position sensing signal to the controller 11; after receiving the signal, the controller 11 determines that the fork 14 has reached the high-position deceleration point of the mast, and then adjusts the speed of the oil pump motor 6 according to the preset control parameters, and simultaneously reduces the flow opening of the solenoid valve 7; by reducing the flow and pressure of the hydraulic oil, the lifting speed of the mast is smoothly reduced from the rated speed to a low speed, eliminating most of the motion inertia.

[0043] Precise shutdown phase: After the gantry enters the low-speed lifting phase, the pressure sensor 8 collects the oil pressure signal of the lifting oil circuit in real time and transmits it to the controller 11; when the oil pressure rises to the preset pressure value of the pressure sensor 8, the pressure sensor 8 sends a pressure trigger signal to the controller 11; after receiving the signal, the controller 11 immediately controls the oil pump motor 6 to stop running and completely closes the solenoid valve 7, cutting off the hydraulic oil supply circuit of the lifting cylinder 3; at this time, the lifting cylinder 3 forms a locked state under the action of the check valve, and the gantry and forks 14 immediately stop lifting and precisely stop at the highest position.

[0044] The lifting sequence is as follows: the forks are lifted to the top individually first, and then the inner mast 2 drives the forks to continue lifting. When the inner mast 2 rises to the mechanical top dead center, the entire vehicle has stopped lifting, and the hydraulic pressure in the lifting circuit will no longer change.

[0045] This invention also provides an electric stacker truck equipped with the aforementioned electric stacker truck gantry lifting control system, which has the advantages of smooth gantry lifting, precise stopping, and safety and reliability.

[0046] The above provides a detailed description of an electric stacker truck gantry lifting control method provided in this application. The specific examples used herein are merely preferred embodiments of the invention, but the scope of protection of this invention is not limited thereto. For those skilled in the art, several equivalent improvements, modifications, and substitutions can be made to this application without departing from the principles of this application, and these improvements, modifications, and substitutions also fall within the scope of protection of the claims of this application.

[0047] It should also be noted that, in this specification, terms such as "comprising," "including," or any other variations are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

Claims

1. A lifting control system for an electric stacker truck gantry, characterized in that, Applications in electric stacker trucks include: Lifting cylinder, hydraulic oil tank, hydraulic pump, oil pump motor, solenoid valve, pressure sensor, proximity switch, sensing plate and controller; The lifting cylinder is used to drive the outer mast and inner mast of the stacker truck to perform lifting actions. The oil outlet of the lifting cylinder is connected to the hydraulic oil tank. The oil inlet of the hydraulic pump is connected to the hydraulic oil tank. The oil outlet of the hydraulic pump is connected to the solenoid valve. The oil outlet of the solenoid valve is connected to the oil inlet of the lifting cylinder. The oil pump motor is connected to the hydraulic pump drive and is used to drive the hydraulic pump to operate. The pressure sensor is connected to the lifting pressure detection port of the solenoid valve and is used to detect the oil pressure in the lifting oil circuit in real time. The sensing plate is fixedly mounted on the inner gantry, and the proximity switch is arranged and installed on the outer gantry corresponding to the sensing plate; The oil pump motor, solenoid valve, proximity switch, and pressure sensor are all electrically connected to the controller. The proximity switch is used to detect the position of the sensing plate and send a position sensing signal to the controller. The controller determines whether the forks have reached the high position of the mast based on the position sensing signal. When it is determined that the forks have reached the high position of the mast, the controller reduces the mast lifting speed by adjusting the speed of the oil pump motor and the opening of the solenoid valve hydraulic oil flow. The controller is set with a preset pressure value, which is less than the overflow pressure of the hydraulic system. When the oil pressure in the lifting oil circuit reaches the preset pressure value, the pressure sensor sends a pressure trigger signal to the controller. After receiving the pressure trigger signal, the controller controls the oil pump motor to stop, so that the gantry stops lifting and stops at the highest position.

2. The electric stacker gantry lifting control system according to claim 1, characterized in that, A check valve is provided between the solenoid valve and the inlet of the lifting cylinder, and the inlet of the check valve is connected to the outlet of the solenoid valve. The outlet of the check valve is divided into two paths, one of which is connected to the inlet of the lifting cylinder and the other of which is connected to the relief valve. The pressure sensor is installed on the lifting pressure detection port of the oil passage connecting the outlet of the check valve and the inlet of the lifting cylinder, and the outlet of the relief valve is connected to the hydraulic oil tank.

3. The electric stacker gantry lifting control system according to claim 1, characterized in that, The pressure sensor feeds back the oil pressure signal to the controller, which then coordinates the start and stop of the oil pump motor and the opening of the solenoid valve based on the oil pressure signal to achieve fork lifting and stopping control.

4. The electric stacker gantry lifting control system according to claim 1, characterized in that, It also includes an upper buffer bracket, which is fixed to the edge of the upper crossbeam of the outer gantry, and the proximity switch is fixedly installed on the upper buffer bracket.

5. The electric stacker gantry lifting control system according to claim 1, characterized in that, It also includes an integrated handle, which is mounted on the stacker truck's steering arm and electrically connected to the controller. The integrated handle is used to input lifting operation commands to the controller, which drives the oil pump motor and solenoid valve to operate according to the lifting operation commands, thereby controlling the lifting operation of the forks.

6. The electric stacker gantry lifting control system according to claim 1, characterized in that, It also includes a battery, which is connected to the power supply terminal of the controller. The controller supplies power to the oil pump motor, solenoid valve, proximity switch and pressure sensor through an internal power supply circuit.

7. A method for controlling the lifting of an electric stacker truck gantry, characterized in that, The electric stacker gantry lifting control system according to any one of claims 1 to 6 includes the following steps: When the stacker truck performs gantry lifting operations, the proximity switch detects the position of the sensing plate in real time. When the sensing plate approaches the proximity switch, the proximity switch sends a position sensing signal to the controller. The controller determines in real time whether it receives a position sensing signal from the proximity switch. If no position sensing signal is received, the controller controls the oil pump motor and solenoid valve to operate according to the set instructions, and the mast maintains a normal lifting speed. If a position sensing signal is received, it is determined that the forks have reached the high position of the mast, and the controller limits the mast lifting speed according to preset parameters, that is, the mast lifting speed is reduced. After the gantry enters the low-speed lifting stage, the pressure sensor collects the lifting oil pressure of the solenoid valve in real time and compares it with the built-in preset pressure value. If the oil pressure in the oil circuit does not reach the preset pressure value, the pressure sensor continues to detect the oil pressure and the gantry maintains low-speed lifting; if the oil pressure in the oil circuit reaches the preset pressure value, the pressure sensor sends a pressure trigger signal to the controller. After receiving the pressure trigger signal, the controller stops the oil pump motor and closes the solenoid valve, cutting off the hydraulic oil supply to the lifting cylinder. The gantry then stops lifting and locks in the highest position.

8. The electric stacker gantry lifting control method according to claim 7, characterized in that, The specific method for slowing down the gantry lifting speed is as follows: the controller reduces the opening of the solenoid valve, reduces the hydraulic oil flow rate in the lifting cylinder, and at the same time matches and lowers the speed of the oil pump motor to achieve uniform and low-speed lifting of the gantry.

9. The electric stacker gantry lifting control method according to claim 7, characterized in that, The specific method for terminating the lifting of the gantry is as follows: the controller stops the oil pump motor, the solenoid valve is completely closed, the hydraulic oil circuit between the lifting cylinder and the hydraulic pump is disconnected, the lifting cylinder is locked, and the gantry and forks are stationary.

10. An electric stacker truck, characterized in that, It is equipped with the electric stacker gantry lifting control system as described in any one of claims 1 to 6.

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