Fork head damping system of three-way forklift

Abstract

The invention discloses a three-way forklift fork head damping system which comprises a lateral movement servo motor assembly, a rotary servo motor assembly, a servo control module, a position feedback module and a vehicle-mounted PLC. When the lateral moving servo motor assembly and the rotating servo motor assembly are used, the bridge frame can laterally move on the sliding frame, the pallet fork can rotate along the bridge frame, power is provided for lateral moving and rotating actions through a servo motor, and three-ring closed-loop control over a current ring, a speed ring and a position ring is achieved through a servo driver. The gear transmission return clearance is effectively eliminated, the control precision is improved, the response speed is increased, and the whole-process vibration-free operation of lateral movement and rotation of the pallet fork is conveniently achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial vehicles, and in particular to a three-way forklift fork head shock absorption system. Background Art

[0002] With the rapid development of the warehousing and logistics industry and the increasing cost of urban land, the forklift market is seeing a growing demand for narrow-aisle forklifts. Three-way stacker trucks, as efficient narrow-aisle forklifts, feature rotating and lateral shifting forks, enabling cargo reversal and loading and unloading from shelves, significantly increasing storage capacity and reducing land investment costs. However, existing technologies for using three-way stacker trucks for aisle operations present significant limitations in terms of their lateral shift and rotation mechanisms.

[0003] Currently, most three-way stackers on the market use hydraulic motors or brushless DC motors to drive the lateral movement and rotation of the forks. Hydraulic motors drive the lateral movement and rotation of the forks, but due to hydraulic shock, they experience significant vibration during rapid lateral movement and rotation, preventing smooth and quick starts and stops. While brushless DC motors offer stable and controllable speed, resulting in high speed, smooth, and impact-free rotation and lateral movement, they can also cause vibration during sudden starts and stops due to load inertia and the motor's acceleration and deceleration torque, leading to large following errors and poor linkage performance.

[0004] To address this issue, the traditional approach is to reduce the motor's acceleration and deceleration rates, ensuring smooth, impact-free transitions during lateral movement and rotational start and stop. However, while this approach can address the stability issues associated with lateral movement and rotational start and stop, it cannot effectively address the vibrations of the forkhead during these movements, significantly impacting vehicle control stability and operational efficiency. Summary of the Invention

[0005] The purpose of the present invention is to provide a three-way forklift fork head shock absorption system for solving the vibration problem of the fork head during the lateral movement and rotation movement during the rapid start and stop lateral movement and rotation operation of the traditional three-way forklift.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A three-way forklift fork head shock absorption system, comprising:

[0008] A lateral shift servo motor assembly is mounted on the bridge, the lateral shift servo motor assembly is connected to a gear shaft via a gear meshing transmission, and the gear shaft is connected to a rack on the slide via a gear meshing transmission, thereby achieving lateral shift of the bridge along the slide;

[0009] A rotary servo motor assembly is mounted on the bridge frame. The rotary servo motor assembly is connected to the front axle via a gear meshing transmission. The front axle is fixedly connected to the fork frame via screws. The fork frame is provided with a fork to achieve angular rotation of the fork.

[0010] A servo control module comprising a side shift servo driver and a rotation servo driver, wherein the side shift servo driver is electrically connected to the side shift servo motor assembly, and the rotation servo driver is electrically connected to the rotation servo motor assembly;

[0011] A position feedback module includes a lateral absolute encoder and a rotary absolute encoder. The lateral absolute encoder is used to provide real-time feedback on the lateral position data of the fork, and the rotary absolute encoder is used to provide real-time feedback on the rotation angle position data of the fork.

[0012] The vehicle-mounted PLC controller obtains feedback values ​​of the fork's lateral position data and the fork's rotation angle position data through CANopen communication. The vibration reduction algorithm module included in the vehicle-mounted PLC controller is based on the three-loop closed-loop control of the current loop, speed loop, and position loop, and uses an S-curve function to optimize the acceleration and deceleration pulse instructions to suppress the vibration of the fork end.

[0013] As a further solution of the present invention: the side shift servo driver receives the fork lateral side shift target position instruction from the on-board PLC controller through CANopen communication, calculates the position error in combination with the feedback value of the side shift absolute encoder, and dynamically adjusts the three-loop closed-loop parameters of the side shift motor current loop, speed loop and position.

[0014] As a further solution of the present invention: the rotary servo driver receives the fork rotation angle target position instruction from the on-board PLC controller through CANopen communication, calculates the position error in combination with the feedback value of the rotary absolute encoder, and dynamically adjusts the three-loop closed-loop parameters of the rotary motor current loop, speed loop and position.

[0015] As a further solution of the present invention: when the shock absorption algorithm module adopts the S-curve function to optimize the acceleration and deceleration pulse instructions, the load speed on the fork is positively correlated with the buffer distance, the greater the speed, the longer the buffer distance, and the lower the speed, the shorter the buffer distance.

[0016] As a further solution of the present invention: the side-shift servo motor assembly includes a speed sensor 1 and a current sensor 1, the speed sensor 1 is used to provide real-time feedback of the servo motor speed data in the side-shift servo motor assembly, and the current sensor 1 is used to provide real-time feedback of the servo motor current data.

[0017] As a further solution of the present invention: the rotary servo motor assembly includes a second speed sensor and a second current sensor. The second speed sensor is used to provide real-time feedback of the rotary motor speed data in the rotary servo motor assembly, and the second current sensor is used to provide real-time feedback of the rotary motor current data.

[0018] As a further solution of the present invention: a lateral movement into position sensing switch is provided on the bridge, and both ends of the slide are respectively provided with sensing plates that form an electronic limit structure with the lateral movement into position sensing switch.

[0019] As a further solution of the present invention: a rotation-in-place sensing switch is further provided on the bridge frame, and a rotation-in-place sensing plate is provided at the rear end of the front axle to form an electronic limit structure with the rotation-in-place sensing switch.

[0020] As a further solution of the present invention: a drag chain is provided on the slide, the drag chain moves synchronously with the bridge, and a power supply cable is arranged inside the drag chain.

[0021] As a further solution of the present invention: the three-closed-loop control of the shock absorption algorithm module is used to eliminate the gear meshing transmission return clearance, and the control accuracy error is ≤0.1mm.

[0022] Beneficial effects of the present invention:

[0023] (1) The present invention suppresses the vibration by outputting acceleration and deceleration pulse instructions, thereby alleviating the contradiction between the load inertia and the motor acceleration and deceleration torque when the load suddenly starts or stops, and can realize the rapid and stable start and stop of the rotation and lateral movement of the three-way forklift fork, so as to effectively suppress the terminal vibration and thus improve the steady-state accuracy of the servo system;

[0024] (2) The servo drive of the present invention covers the current loop, the speed loop and the position loop, and can realize true three-loop closed-loop control through the superior buffer S-curve function, effectively eliminating the gear transmission return clearance, making the control more precise, the response faster and more sensitive, and making the fork head of the three-way forklift run fast, smoothly and without vibration during the lateral movement and rotation, so as to realize the full vibration-free operation of the lateral movement and rotation of the fork. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The present invention will be further described below with reference to the accompanying drawings.

[0026] Figure 1 It is a framework diagram of a three-way forklift fork shock absorption system of the present invention;

[0027] Figure 2 This is a structural schematic diagram of a three-way forklift fork head shock-absorbing structure of the present invention;

[0028] Figure 3 This is a schematic diagram of a three-way forklift fork head shock absorption system according to the present invention;

[0029] Figure 4 It is a schematic diagram of the relationship between speed and distance in the S-curve function of the present invention;

[0030] Figure 5 It is a flow chart of the fork head vibration reduction method of the present invention.

[0031] In the figure: 1. Slide; 11. Rack; 12. Sensor plate; 13. Drag chain; 2. Bridge; 21. Side shift servo motor assembly; 22. Rotation servo motor assembly; 23. Side shift servo driver; 24. Rotation servo driver; 25. Side shift in-position sensor switch; 26. Rotation in-position sensor switch; 27. Rotation absolute encoder; 28. Side shift absolute encoder; 29. ​​Gear shaft; 210. Rotation in-position sensor plate; 211. Front axle; 3. Fork frame; 4. Fork; 5. Servo control module; 6. Vehicle-mounted PLC controller; 7. Shock absorption algorithm module; 8. Position feedback module. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0033] In the description of the present invention, it should be understood that the terms indicating orientation or positional relationship are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; in the description of the present invention, the meaning of "multiple" and "several" is at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0034] See also Figures 1 to 3As shown, the present invention is a three-way forklift forkhead shock absorption system, including a side shift servo motor assembly 21, a rotation servo motor assembly 22, a servo control module 5, a position feedback module 8 and an on-board PLC controller 6; the forkhead of the three-way forklift includes the side shift and rotation functions of the fork 4, and the power of the side shift servo motor assembly 21 and the rotation servo motor assembly 22 comes from the electronic control system of the on-board PLC controller 6, so that the side shift and rotation actions are realized by the motors with corresponding functions; at the same time, a hydraulic system composed of hydraulic components such as hydraulic motors can also be used to realize it. In the process of realizing the side shift and rotation functions of the fork 4 in this application, power is provided by the servo motors with corresponding functions. This application realizes three-loop closed-loop control of current loop, speed loop and position loop through the servo drivers with corresponding functions, which can effectively eliminate the gear transmission return clearance during the operation of the side shift servo motor assembly 21 and the rotation servo motor assembly 22, thereby improving the control accuracy and response speed, so as to suppress the vibration of the end of the fork 4.

[0035] When designing the side shift servo motor assembly 21 and the rotation servo motor assembly 22 in the shock absorption system of the present application, the side shift servo motor assembly 21 is installed on the bridge 2, and the side shift servo motor assembly 21 is connected to the gear shaft 29 through gear meshing transmission, and the gear shaft 29 is connected to the rack 11 on the slide 1 through gear meshing transmission, so that the bridge 2 can move laterally along the slide 1; the rotation servo motor assembly 22 is installed on the bridge 2, and the rotation servo motor assembly 22 is connected to the front axle 211 through gear meshing transmission, and the front axle 211 is fixedly connected to the fork frame 3 through screws, and the fork frame 3 is provided with a fork 4 to realize the angle rotation of the fork 4; the slide 1 is provided with a drag chain 13, which moves synchronously with the bridge 2, and a power supply cable is arranged inside it, and the power supply in the bridge 2 assembly is supplied through the vehicle body, and the cable is arranged in the drag chain 13 assembly after passing through mechanisms such as the gantry pulley, to ensure that the cable moves with the bridge 2 assembly.

[0036] During the use of the lateral shift servo motor assembly 21 and the rotation servo motor assembly 22 in the shock absorption system of the present application, a lateral shift position sensing switch 25 is provided on the bridge 2, and both ends of the slide 1 are respectively provided with sensing plates 12 that form an electronic limit structure with the lateral shift position sensing switch 25 to achieve limit control of the lateral shift end point of the bridge 2; a rotation position sensing switch 26 is also provided on the bridge 2, and a rotation position sensing plate 210 that forms an electronic limit structure with the rotation position sensing switch 26 is provided at the tail end of the front axle 211 in the rotation servo motor assembly 22 to achieve limit control of the end position of the rotation angle of the fork frame 3 driven by the front axle 211.

[0037] When designing the functional modules in the shock absorption system of the present application, the servo control module 5 includes a side shift servo driver 23 and a rotary servo driver 24. The side shift servo driver 23 is electrically connected to the side shift servo motor assembly 21, and the rotary servo driver 24 is electrically connected to the rotary servo motor assembly 22; the position feedback module 8 includes a side shift absolute encoder 28 and a rotary absolute encoder 27. The side shift absolute encoder 28 is used to provide real-time feedback on the lateral side shift position data of the fork 4, and the rotary absolute encoder 27 is used to provide real-time feedback on the rotation angle position data of the fork 4; the on-board PLC controller 6 obtains the feedback values ​​of the lateral side shift position data and the rotation angle position data of the fork 4 through CANopen communication. The shock absorption algorithm module 7 included in the on-board PLC controller 6 is based on the three-loop closed-loop control of the current loop, the speed loop, and the position loop, and adopts the S-curve function to optimize the acceleration and deceleration pulse instructions to suppress the end vibration of the fork 4.

[0038] When the bridge 2 moves laterally or the fork 4 rotates, the side-shifting servo motor assembly 21 includes a speed sensor 1 and a current sensor 1. The speed sensor 1 is used to provide real-time feedback on the servo motor speed data in the side-shifting servo motor assembly 21, and the current sensor 1 is used to provide real-time feedback on the servo motor current data, so as to facilitate real-time detection and feedback on the current and speed information of the motor corresponding to the side-shifting function; the rotating servo motor assembly 22 includes a speed sensor 2 and a current sensor 2. The speed sensor 2 is used to provide real-time feedback on the rotating motor speed data in the rotating servo motor assembly 22, and the current sensor 2 is used to provide real-time feedback on the rotating motor current data, so as to facilitate real-time detection and feedback on the current and speed information of the motor corresponding to the rotation function.

[0039] When the bridge 2 moves laterally or the fork 4 rotates, the side shift servo driver 23 receives the target position instruction of the fork 4 lateral movement from the onboard PLC controller 6 through CANopen communication, calculates the position error in combination with the feedback value of the side shift absolute encoder 28, and dynamically adjusts the three-loop closed-loop parameters of the side shift motor current loop, speed loop and position; the rotation servo driver 24 receives the target position instruction of the fork 4 rotation angle from the onboard PLC controller 6 through CANopen communication, calculates the position error in combination with the feedback value of the rotation absolute encoder 27, and dynamically adjusts the three-loop closed-loop parameters of the rotation motor current loop, speed loop and position; the present application can calculate the position corresponding to the side shift and rotation based on the absolute position feedback value of the current encoder of the corresponding position of the side shift and rotation. The side shift servo driver 23 controls the current loop, speed loop and position loop of the side shift servo motor according to the target position instruction of the on-board PLC controller 6; the rotation servo driver 24 controls the current loop, speed loop and position loop of the rotation motor according to the speed instruction of the on-board PLC controller 6. The current loop is used to monitor the motor torque fluctuation in real time and suppress instantaneous load impact; the speed loop dynamically adjusts the speed through encoder feedback to eliminate the gear return clearance; the position loop associates the side shift with the rotation position; when reaching the target position or stopping midway, the three closed-loop control of the shock absorption algorithm module 7 is used to eliminate the gear meshing transmission return clearance, and the control accuracy error is ≤0.1mm. The S-curve function can be used to optimize the acceleration and deceleration pulse instructions to suppress the vibration of the fork end 4.

[0040] When the bridge 2 moves laterally or the fork 4 rotates, the present invention aims to eliminate the vibration problem caused by the end of the three-way forklift fork head during the rapid start-stop positioning operation with load by optimizing the acceleration and deceleration rate curve. Specifically, Figure 4 As shown, when the shock absorption algorithm module 7 uses the S-curve function to optimize the acceleration and deceleration pulse instructions, the load speed on the fork 4 is positively correlated with the buffer distance. The greater the speed, the longer the buffer distance, and the smaller the speed, the shorter the buffer distance. Before the fork head of the three-way forklift reaches the final positioning point, a gradual acceleration and deceleration process is given for a period of time, which effectively resolves the contradiction between the load inertia and the acceleration and deceleration torque, and achieves fast starting and stopping without shaking.

[0041] like Figure 5 As shown, based on the above-mentioned shock absorption system, this application proposes a three-way forklift fork head shock absorption method, comprising the following steps:

[0042] S1. Obtain the position of the fork 4 in real time through the lateral absolute encoder 28 and the rotary absolute encoder 27.

[0043] S2 , the onboard PLC controller 6 calculates the lateral displacement position error based on the displacement target position function and the feedback value of the displacement absolute encoder 28 , and calculates the rotational angle position error based on the rotational target position function and the feedback value of the rotational absolute encoder 27 .

[0044] S3, the side shift servo driver 23 dynamically adjusts the three-loop closed-loop parameters of the side shift motor current loop, speed loop, and position loop according to the lateral side shift position error value, and the rotation servo driver 24 dynamically rotates the motor to adjust the three-loop closed-loop parameters of the current loop, speed loop, and position loop according to the rotation angle position error.

[0045] S4: Before lateral movement and rotation to the target position, an S-curve function is used to generate acceleration and deceleration pulse instructions to suppress the vibration of the fork end 4.

[0046] This method can effectively suppress terminal vibration and thus improve the steady-state accuracy of the servo system; by suppressing it through acceleration and deceleration pulse output instructions, the contradiction between the load inertia and the motor acceleration and deceleration torque when the load suddenly starts or stops is reduced, and the three-way forklift fork 4 rotation and lateral shift can be started and stopped quickly and stably. The servo driver covers the current loop, speed loop and position loop, and can realize true three-loop closed-loop control through the excellent buffer S curve function, effectively eliminating the gear transmission return clearance, making the control more precise, the response faster and more sensitive, and making the fork head of the three-way forklift run quickly, smoothly and without vibration during the lateral shift and rotation action, so as to realize the full vibration-free operation of the lateral shift and rotation of the fork 4.

[0047] The above is a detailed description of an embodiment of the present invention. However, the content described is only a preferred embodiment of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A three-way forklift fork head shock absorption system, characterized in that: include: A lateral shift servo motor assembly (21) is mounted on the bridge (2), wherein the lateral shift servo motor assembly (21) is connected to a gear shaft (29) through a gear meshing transmission, and the gear shaft (29) is connected to a rack (11) on the slide (1) through a gear meshing transmission, thereby realizing lateral shifting of the bridge (2) along the slide (1); A rotary servo motor assembly (22) is mounted on the bridge (2), wherein the rotary servo motor assembly (22) is connected to the front axle (211) via a gear meshing transmission, wherein the front axle (211) is fixedly connected to the fork frame (3) via screws, and the fork frame (3) is provided with a fork (4) to achieve angular rotation of the fork (4); A servo control module (5) includes a lateral servo driver (23) and a rotary servo driver (24), wherein the lateral servo driver (23) is electrically connected to the lateral servo motor assembly (21), and the rotary servo driver (24) is electrically connected to the rotary servo motor assembly (22); A position feedback module (8), comprising a lateral absolute value encoder (28) and a rotary absolute value encoder (27), wherein the lateral absolute value encoder (28) is used to provide real-time feedback of lateral lateral position data of the fork (4), and the rotary absolute value encoder (27) is used to provide real-time feedback of rotational angle position data of the fork (4); The vehicle-mounted PLC controller (6) obtains feedback values ​​of lateral position data of the fork (4) and rotation angle position data of the fork (4) through CANopen communication. The vehicle-mounted PLC controller (6) includes a vibration reduction algorithm module (7) based on a three-loop closed-loop control of a current loop, a speed loop, and a position loop, and uses an S-curve function to optimize acceleration and deceleration pulse instructions to suppress vibration at the end of the fork (4).

2. A three-way forklift fork head shock absorption system according to claim 1, characterized in that: The side shift servo driver (23) receives the lateral side shift target position instruction of the fork (4) from the vehicle-mounted PLC controller (6) through CANopen communication, calculates the position error in combination with the feedback value of the side shift absolute encoder (28), and dynamically adjusts the three-loop closed-loop parameters of the side shift motor current loop, speed loop and position.

3. A three-way forklift fork head shock absorption system according to claim 1, characterized in that: The rotary servo driver (24) receives the target position instruction of the rotation angle of the fork (4) from the vehicle-mounted PLC controller (6) via CANopen communication, calculates the position error in combination with the feedback value of the rotary absolute encoder (27), and dynamically adjusts the three closed-loop parameters of the rotary motor current loop, speed loop and position.

4. A three-way forklift fork head shock absorption system according to claim 1, characterized in that: When the shock absorption algorithm module (7) uses an S-curve function to optimize the acceleration and deceleration pulse instructions, the load speed on the fork (4) is positively correlated with the buffer distance. The greater the speed, the longer the buffer distance, and the lower the speed, the shorter the buffer distance.

5. The three-way forklift fork head shock absorption system according to claim 1, characterized in that: The side shift servo motor assembly (21) comprises a speed sensor 1 and a current sensor 1, wherein the speed sensor 1 is used for real-time feedback of servo motor speed data in the side shift servo motor assembly (21), and the current sensor 1 is used for real-time feedback of servo motor current data.

6. A three-way forklift fork head shock absorption system according to claim 1, characterized in that: The rotary servo motor assembly (22) comprises a second speed sensor and a second current sensor. The second speed sensor is used to feed back the rotary motor speed data in the rotary servo motor assembly (22) in real time, and the second current sensor is used to feed back the rotary motor current data in real time.

7. The three-way forklift fork head shock absorption system according to claim 1, characterized in that: The bridge (2) is provided with a side-moving-in-place sensing switch (25), and both ends of the slide (1) are respectively provided with sensing plates (12) that form an electronic limit structure with the side-moving-in-place sensing switch (25).

8. The three-way forklift fork head shock absorption system according to claim 1, characterized in that: The bridge frame (2) is also provided with a rotation-in-place sensing switch (26), and the rear end of the front axle (211) is provided with a rotation-in-place sensing plate (210) that forms an electronic limit structure with the rotation-in-place sensing switch (26).

9. The three-way forklift fork head shock absorption system according to claim 1, characterized in that: The slide (1) is provided with a drag chain (13), which moves synchronously with the bridge (2) and has a power supply cable arranged inside the drag chain (13).

10. The three-way forklift fork head shock absorption system according to claim 1, characterized in that: The three-closed-loop control of the vibration reduction algorithm module (7) is used to eliminate the gear meshing transmission return clearance, and the control accuracy error is ≤0.1mm.

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