A steering control system and a pallet jack

Abstract

This invention relates to the field of logistics handling equipment technology, specifically disclosing a steering control system and a pallet transport vehicle. The steering control system is used in a pallet transport vehicle, which includes a frame, a vehicle controller, drive wheels, and a gearbox connected to the drive wheels. The steering control system includes a mounting plate mounted on the frame, a steering motor mounted on the mounting plate and signal-connected to the vehicle controller, and a first gear fixed to the output shaft of the steering motor. The gearbox is rotatably mounted on the mounting plate; a second gear is coaxially mounted on the gearbox and meshes with the first gear, allowing the gearbox and drive wheels to rotate with the rotation of the second gear. This invention achieves integrated electric steering and drive structure by driving the meshing first and second gears with the steering motor, thereby rotating the gearbox and drive wheels as a whole. This results in a compact layout and saves installation space. The vehicle controller can flexibly adjust the steering force, improving operational comfort.

Description

Technical Field

[0001] This invention relates to the field of logistics handling equipment technology, and in particular to a steering control system and a pallet transport vehicle. Background Technology

[0002] Pallet trucks are a type of forklift and are one of the most basic and widely used loading and unloading equipment in the logistics handling field. They are mainly used for short-distance transport of palletized goods on flat ground.

[0003] There are two main types of steering mechanisms for existing pallet trucks. One is mechanical steering, which directly drives the steering wheels by turning a handle, but the steering force is relatively large, and the operator is prone to fatigue. The other is hydraulic steering, which relies on a gear pump to drive hydraulic oil as a medium. When the handle is turned left or right, the mechanical structure drives the opening and closing of the left and right oil circuits of the steering gear, which drives the steering wheels to rotate through the oil cylinder. However, it has problems such as larger installation space requirements and oil leakage. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a steering control system and a pallet truck that solves the problems of uncontrollable steering operation, large space requirements, and oil leakage in the prior art.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a steering control system for a pallet truck. The pallet truck includes a frame, a vehicle controller, drive wheels, and a gearbox connected to the drive wheels. The steering control system includes a mounting plate, a steering motor, a first gear, and a second gear. The mounting plate is mounted on the frame, the steering motor is mounted on the mounting plate and signal-connected to the vehicle controller, and the first gear is fixed to the output shaft of the steering motor. The gearbox is rotatably mounted on the mounting plate. The second gear is coaxially mounted on the gearbox and meshes with the first gear. The gearbox and the drive wheels can rotate with the rotation of the second gear.

[0006] This invention achieves integrated electric steering and drive structure by driving meshing gears one and two with a steering motor, thereby rotating the gearbox and drive wheels as a whole. The layout is compact and saves installation space. The vehicle controller can flexibly adjust the steering force to improve operating comfort. Compared with mechanical steering, the operating force is significantly reduced, and compared with hydraulic steering, the risk of oil leakage is avoided.

[0007] As a further improvement to the above-described solution of the present invention, the steering control system further includes an encoder connected to the vehicle controller signal. The encoder's reading head is mounted on a mounting plate, and the encoder's gear meshes with gear two. By adding an encoder meshing with gear two, the actual rotation angle of the drive wheels is acquired in real time and fed back to the vehicle controller, forming a closed-loop steering angle control.

[0008] As a further improvement to the above-described solution of the present invention, the steering control system further includes a position sensor connected to the vehicle controller. The position sensor is mounted on a mounting plate, and a sensing strip is provided on the gear two. The position sensor is used to detect the position of the sensing strip when the vehicle starts. When the position sensor does not detect the sensing strip, the vehicle controller controls the drive motor to start, thereby driving the gear two to rotate until the position sensor detects the sensing strip. Through the cooperation of the position sensor and the sensing strip on the gear two, the starting position of the drive wheels is automatically detected when the vehicle starts; if the sensing strip is not detected, the drive motor is controlled to adjust the rotation of the gear two until the sensing strip is detected, thereby achieving automatic alignment of the drive wheels, ensuring straight-line driving of the vehicle, and reducing driver correction operations.

[0009] As a further improvement to the above-described solution of the present invention, the diameter of gear two is larger than the diameter of gear one. The larger diameter of gear two creates a speed reduction and torque amplification transmission, increasing the steering torque output, reducing the load on the steering motor, and simultaneously improving the accuracy and response speed of steering control.

[0010] As a further improvement to the above-described solution of the present invention, the diameter of the encoder gear is smaller than the diameter of the second gear. The smaller diameter of the encoder gear allows the encoder to detect minute angular changes in the second gear at a higher resolution, thereby improving the accuracy of angle feedback and further optimizing the angular synchronization control effect.

[0011] As a further improvement to the above-described solution of the present invention, the steering control system further includes a handle control mechanism, which includes a handle, a mounting bracket, a rotating seat, a slewing bearing, a torque feedback device, a connecting rod, and a pin. The mounting bracket is mounted on the vehicle frame, the rotating seat is rotatably mounted on the mounting bracket via the slewing bearing, the torque feedback device is mounted on the inner ring of the slewing bearing and rotates synchronously with the rotating seat, the torque feedback device is signal-connected to the vehicle controller, and the vehicle controller drives the drive motor to start after receiving a signal from the torque feedback device; the connecting rod is rotatably mounted on the rotating seat via a horizontally arranged pin, and the handle is connected to the connecting rod. The handle control mechanism uses a slewing bearing to reduce steering friction and integrates a torque feedback device, which can adjust the handle control force in real time according to vehicle speed, steering angle, and speed, avoiding fatigue caused by excessive steering force or excessive force caused by insufficient steering force; the handle swings up and down via the pin, adapting to different operating postures (person in or out of the vehicle), improving the convenience of operation.

[0012] As a further improvement to the above-mentioned solution of the present invention, the torque feedback device includes a TFD body and a TFD rotary shaft. The TFD body is coaxially mounted within the inner ring of the rotary bearing and has a built-in steering position sensor for acquiring the rotation angle of the TFD body. The TFD rotary shaft is fixed on a mounting bracket, and the steering position sensor is signal-connected to the vehicle controller. The TFD body rotates with the inner ring of the rotary bearing, and the built-in steering position sensor accurately acquires the rotation angle of the steering handle and transmits it to the vehicle controller to drive the steering motor. The TFD rotary shaft is fixed to the mounting bracket, forming a stable relative motion, realizing steer-by-wire while providing variable feedback torque, allowing the operator to obtain a realistic road feel and improving driving safety and comfort.

[0013] As a further improvement to the above-mentioned solution of the present invention, an indexing plunger is provided on the rotating seat. When the handle is rotated downward to its limit, pressing the button on the indexing plunger causes its pin to extend and abut against the top of the connecting rod to limit the rotation of the connecting rod. By setting the indexing plunger, when the handle is rotated downward to its limit, pressing the button on the indexing plunger can lock the connecting rod and fix the handle angle. This structure is simple and reliable, suitable for picking operations, and prevents the handle from accidentally returning to its original position or being misoperated.

[0014] As a further improvement to the above-described solution of the present invention, a sensor for detecting the indexing plunger button is provided on the rotating base. The sensor is signal-connected to the vehicle controller, and the vehicle controller adjusts the rotation speed of the drive wheels when it receives the sensor signal. By providing a sensor for detecting the indexing plunger button on the rotating base, when the indexing plunger button is pressed, the sensor detects the button and sends a signal to the vehicle controller, automatically limiting the maximum speed of the drive wheels. This achieves graded speed limiting under different working conditions, significantly improving operational safety.

[0015] The present invention also provides a pallet truck including the steering control system described above. The pallet truck including the aforementioned steering control system integrates multiple functions such as electric steering, closed-loop feedback of steering angle, automatic centering, adjustable control force, and working condition speed limiting. It has a compact structure, no risk of hydraulic leakage, is easy to operate, safe and reliable, and significantly improves the overall vehicle's handling comfort and operational safety. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the steering operating system in an embodiment of the present invention; Figure 2 This is a partial structural diagram of the steering operating system in an embodiment of the present invention; Figure 3 for Figure 2 Side view; Figure 4 This is a schematic diagram of the handle operation mechanism in an embodiment of the present invention; Figure 5 This is a cross-sectional view of the handle operating mechanism in an embodiment of the present invention; Figure 6 This is a partial structural diagram of the handle operation mechanism in an embodiment of the present invention; Figure 7 A schematic diagram of the indexing plunger in an embodiment of the present invention.

[0017] Reference numerals: 1. Frame; 2. Drive wheel; 3. Gearbox; 4. Mounting plate; 5. Steering motor; 6. Gear 1; 7. Gear 2; 8. Encoder; 9. Position sensor; 10. Sensing strip; 11. Traction motor; 12. Handle; 13. Mounting bracket; 14. Rotary seat; 15. Slewing bearing; 16. Torque feedback device; 17. Connecting rod; 18. Pin; 19. Indexing plunger; 20. Sensor; 21. Nut. Detailed Implementation

[0018] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0020] Reference Figure 1 This embodiment proposes a pallet transport vehicle, which includes a frame 1, drive wheels 2, a gearbox 3, a vehicle controller, a traction motor 11 connected to the gearbox 3, and a steering control system. Combined with... Figure 2 The steering control system includes a mounting plate 4, a steering motor 5, a first gear 6 and a second gear 7, and also includes a handle control mechanism.

[0021] Mounting plate 4 is fixedly mounted on the vehicle frame 1. Steering motor 5 is fixedly mounted on mounting plate 4 and is connected to the vehicle controller for receiving steering commands. Gear 6 is coaxially fixed on the output shaft of steering motor 5.

[0022] The gearbox 3 is rotatably mounted on the mounting plate 4. Specifically, the upper end of the gearbox 3 is rotatably connected to the mounting plate 4 via a slewing bearing (not shown in the figure). The drive wheel 2 is mounted on the output end of the gearbox 3. Gear 2 7 is coaxially fixedly mounted on the upper part of the housing of the gearbox 3 and meshes with gear 6.

[0023] When the steering motor 5 rotates, gear 6 drives gear 7 to rotate, and gear 7 drives the gearbox 3 and drive wheel 2 to rotate together relative to the mounting plate 4, thereby realizing the steering action of the whole vehicle. Preferably, the diameter of gear 7 is larger than the diameter of gear 6 to form a speed reduction and torque increase transmission, thereby improving the steering torque.

[0024] To achieve synchronized control of the drive wheel rotation angle and the steering handle rotation angle, the steering control system also includes an encoder 8. The reading head of the encoder 8 is fixedly mounted on the mounting plate 4, and the gear of the encoder 8 meshes with gear 7. The encoder 8 is connected to the vehicle controller for signal acquisition of the rotation angle of gear 7 in real time, which is the actual steering angle of the drive wheel 2.

[0025] The vehicle controller compares the actual drive wheel rotation angle fed back by encoder 8 with the handle rotation angle fed back by the handle control mechanism (detailed below). If the two are inconsistent, the vehicle controller determines that the steering is out of sync and issues a fault code to the operator to avoid safety hazards caused by misjudgment. Preferably, the diameter of the gear of encoder 8 is smaller than the diameter of gear 7 to improve the resolution of angle detection.

[0026] To achieve automatic centering of the drive wheels during vehicle startup and ensure straight-line driving, combined with Figure 3 The steering control system also includes a position sensor 9 and a sensing strip 10. The position sensor 9 is fixedly mounted on the mounting plate 4 and connected to the vehicle controller. The sensing strip 10 is positioned at a predetermined starting position on gear 7. When the vehicle starts, the position sensor 9 detects whether the sensing strip 10 on gear 7 is within its sensing range. If the position sensor 9 does not detect the sensing strip 10, it indicates that the drive wheel 2 has deviated from its forward center position. The vehicle controller then controls the steering motor 5 to start, driving gear 7 to rotate until the position sensor 9 detects the sensing strip 10. At this point, the drive wheel 2 is parallel to the longitudinal centerline of the frame 1, completing automatic centering.

[0027] The handle control mechanism is used to receive the operator's steering intentions and adjust the control force. Combined Figure 4 , Figure 5 The handle control mechanism includes a handle 12, a mounting bracket 13, a rotating seat 14, a slewing bearing 15, a torque feedback device 16, a connecting rod 17, and a pin 18.

[0028] Mounting bracket 13 is fixedly mounted on the frame 1. Rotary seat 14 is rotatably mounted on mounting bracket 13 via slewing bearing 15. Slewing bearing 15 includes an inner ring and an outer ring, wherein the outer ring is fixed relative to mounting bracket 13, and the inner ring is fixedly connected to rotating seat 14 and can rotate synchronously with rotating seat 14.

[0029] The torque feedback device 16 (TFD) is installed in the inner ring of the slewing bearing 15 and rotates synchronously with the rotating seat 14. The torque feedback device 16 is connected to the vehicle controller and has a built-in steering position sensor (not shown in the figure) for acquiring its own rotation angle.

[0030] The connecting rod 17 is rotatably mounted on the rotating seat 14 via a horizontally arranged pin 18, allowing the connecting rod 17 to swing up and down around the pin 18. The handle 12 is fixedly connected to the upper end of the connecting rod 17.

[0031] Specifically, the torque feedback device 16 includes a TFD body and a TFD rotating shaft. The TFD body is coaxially mounted inside the inner ring of the slewing bearing 15, and the TFD rotating shaft is fixed on the mounting bracket 13. When the operator rotates the handle 12, the rotating seat 14, the inner ring of the slewing bearing 15, and the TFD body rotate together. The steering position sensor inside the TFD body sends the handle rotation angle signal to the vehicle controller, which then drives the steering motor 5 to drive the drive wheel 2 to steer according to the angle. The torque feedback device 16 (TFD) used in this invention is a mature existing technology in the field. Its basic working principle is as follows: based on the current input from the vehicle controller (the vehicle controller determines the output current to the TFD based on the vehicle speed and the handle rotation angle; the faster the vehicle speed and the greater the rate of change of the rotation angle, the greater the output current), different torques are output; the greater the current, the greater the torque. The internal structure, electromagnetic control method, and signal output method of this device are all known technologies, and therefore will not be described in detail here.

[0032] To facilitate picking operations by the operator under the vehicle, handle 12 needs to be fixed at its downward rotation limit, and the overall vehicle speed needs to be automatically limited. Therefore, in conjunction with... Figure 6 , Figure 7 The rotating seat 14 is provided with an indexing plunger 19. The indexing plunger 119 is a commercially available push-button indexing plunger with a locking function. When the handle 12 is rotated downward to the limit, the pin of the indexing plunger 19 is extended by pressing the button to abut against the top of the connecting rod 17 to limit the rotation of the connecting rod 17 and fix the angle of the handle 12.

[0033] When the operator rotates the connecting rod 17 downwards to the limit position (i.e., the handle 12 is rotated to the bottom), the indexing plunger 19 is inserted into the limiting hole, thereby locking the handle 12 and maintaining a fixed angle.

[0034] Furthermore, the rotating base 14 is also equipped with a sensor 20 (e.g., a proximity switch) for detecting the indexing plunger button. The sensor 20 is signal-connected to the vehicle controller. When the indexing plunger button is pressed, the sensor 20 detects it, indicating that the handle 12 is fixed in the picking position. The vehicle controller then controls the maximum speed of the traction motor 11, limiting the maximum vehicle speed to ensure the safety of personnel operating under the vehicle. Conversely, when the handle 12 is not fixed, the vehicle controller allows a higher maximum speed, suitable for transport conditions where personnel are on the vehicle.

[0035] The vehicle controller also adjusts the output torque of the torque feedback device 16 in real time based on the current vehicle speed, handle rotation angle, and rotation angular velocity. Specifically, the higher the vehicle speed, the larger the handle rotation angle, or the greater the rotation angular velocity, the greater the current output by the vehicle controller to the torque feedback device 16, and the greater the counter-torque (i.e., control force) output by the torque feedback device 16, allowing the operator to experience a damping sensation similar to hydraulic steering. Conversely, at lower vehicle speeds or smaller steering angles, the control force decreases accordingly. This function avoids excessive steering force leading to operator fatigue or excessively light steering force leading to overly sharp turns, significantly improving driving comfort and safety.

[0036] Based on the above components, the workflow of this invention is as follows: Vehicle start-up: Position sensor 9 detects sensor strip 10. If they do not match, the drive wheel 2 is automatically adjusted to the center position.

[0037] During operation: The operator turns the handle 12, and the torque feedback device 16 collects the handle rotation angle signal and sends it to the vehicle controller. The vehicle controller adjusts the resistance of the torque feedback device 16 according to the current vehicle speed and the size of the rotation angle. At the same time, it commands the steering motor 5 to rotate, which drives the drive wheel 2 to steer through gear 6 and gear 7.

[0038] Synchronous monitoring: Encoder 8 provides real-time feedback on the actual rotation angle of drive wheel 2, and the vehicle controller determines whether it is consistent with the rotation angle of the handle. If they are inconsistent, an alarm is triggered.

[0039] Picking operation: Turn the handle 12 down to the bottom, the indexing plunger 19 locks the handle 12, and the sensor 20 detects that the vehicle controller limits the speed.

[0040] At different vehicle speeds and turning angles, the vehicle controller automatically adjusts the steering force to provide a comfortable road feel.

[0041] It should be noted that when a component is said to be "installed on" another component, it can be directly on the other component or it may be in a component that is centered on it. When a component is said to be "set on" another component, it can be directly set on the other component or it may also be in a component that is centered on it. When a component is said to be "fixed to" another component, it can be directly fixed to the other component or it may also be in a component that is centered on it.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "or / and" as used herein includes any and all combinations of one or more of the associated listed items.

[0043] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0044] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A steering control system for a pallet truck, the pallet truck comprising a frame (1), a vehicle controller, drive wheels (2), and a gearbox (3) connected to the drive wheels (2); characterized in that, The steering control system includes a mounting plate (4), a steering motor (5), a first gear (6), and a second gear (7). The mounting plate (4) is mounted on the frame (1), the steering motor (5) is mounted on the mounting plate (4) and connected to the vehicle controller via signal. The first gear (6) is fixed on the output shaft of the steering motor (5). The gearbox (3) is rotatably mounted on the mounting plate (4). The second gear (7) is coaxially mounted on the gearbox (3) and meshes with the first gear (6). The gearbox (3) and the drive wheel (2) can rotate with the rotation of the second gear (7).

2. The steering control system according to claim 1, characterized in that, The steering control system also includes an encoder (8) that is connected to the vehicle controller signal. The reading head of the encoder (8) is mounted on the mounting plate (4), and the gear of the encoder (8) meshes with gear two (7).

3. The steering control system according to claim 1, characterized in that, The steering control system also includes a position sensor (9) connected to the vehicle controller. The position sensor (9) is mounted on the mounting plate (4). A sensing strip (10) is provided on the gear two (7). The position sensor (9) is used to detect the position of the sensing strip (10) when the vehicle is started. When the position sensor (9) does not detect the sensing strip (10), the vehicle controller controls the drive motor to start so as to drive the gear two (7) to rotate until the position sensor (9) detects the sensing strip (10).

4. The steering control system according to claim 1, characterized in that, The diameter of gear 2 (7) is greater than the diameter of gear 1 (6).

5. The steering control system according to claim 1, characterized in that, The diameter of the gear of encoder (8) is smaller than the diameter of gear two (7).

6. The steering control system according to claim 1, characterized in that, The steering control system also includes a handle control mechanism, which includes a handle (12), a mounting bracket (13), a rotating seat (14), a slewing bearing (15), a torque feedback device (16), a connecting rod (17), and a pin (18). The mounting bracket (13) is mounted on the vehicle frame (1), the rotating seat (14) is rotatably mounted on the mounting bracket (13) via the slewing bearing (15), the torque feedback device (16) is mounted on the inner ring of the slewing bearing (15) and rotates synchronously with the rotating seat (14), the torque feedback device (16) is signal-connected to the vehicle controller, and the vehicle controller drives the drive motor to start after receiving the signal from the torque feedback device (16); the connecting rod (17) is rotatably mounted on the rotating seat (14) via a horizontally arranged pin (18), and the handle (12) is connected to the connecting rod (17).

7. The steering control system according to claim 6, characterized in that, The torque feedback device (16) includes a TFD body and a TFD rotary shaft. The TFD body is coaxially mounted in the inner ring of the rotary bearing (15) and has a built-in steering position sensor for collecting the rotation angle of the TFD body. The TFD rotary shaft is fixed on the mounting bracket (13) and the steering position sensor is connected to the vehicle controller signal.

8. The steering control system according to claim 6, characterized in that, The rotating seat (14) is provided with an indexing plunger (19). When the handle (12) is rotated downward to the limit, the pin of the indexing plunger (19) is extended by pressing the button to abut the top of the connecting rod (17) to limit the rotation of the connecting rod (17).

9. The steering control system according to claim 8, characterized in that, A sensor (20) for detecting the button of the indexing plunger (19) is provided on the rotating seat (14). The sensor (20) is connected to the vehicle controller signal. When the vehicle controller receives the signal from the sensor (20), it adjusts the rotation speed of the drive wheel.

10. A pallet handling vehicle, characterized in that, It includes the steering control system as described in any one of claims 1-9.

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