Electric forklift driving direction control method, system and mechanical equipment

Abstract

The present application relates to the field of industrial vehicle control, in particular to a forklift driving direction control method, system and mechanical equipment. The system comprises a signal acquisition unit, a control unit, an execution unit and a display unit. The gear handle switch and electronic level of the signal acquisition unit respectively acquire gear signals and vehicle body inclination signals. The vehicle controller and motor controller of the control unit dynamically adjust the direction switching speed threshold value according to the above signals and preset logic: the first threshold value group is used when reversing, the second threshold value group is used when on a slope, and the third threshold value group is used in other cases. The traction motor of the execution unit adjusts the steering according to the motor controller signal. The display unit can configure parameters such as speed threshold value and slope triggering angle. The control method dynamically adjusts the speed threshold value by detecting the gear signal and vehicle body inclination, and realizes direction control. The problems of large reversing impact and difficult slope starting caused by the fixed speed setting value in the prior art are solved, and the driving comfort and safety are improved.

Description

Technical Field

[0001] This invention relates to the field of industrial vehicle control technology, and in particular to an electric forklift driving direction control system and method based on dynamically adjusting the direction switching speed threshold according to vehicle status. It is applicable to mechanical equipment such as electric forklifts and stackers that require precise direction control. Background Technology

[0002] As a core piece of equipment in modern logistics, electric forklifts have undergone an upgrade in their directional control technology, evolving from mechanical linkage to electronic control. Early control schemes (such as gear-fork linkage mechanisms) relied on physical levers to directly switch transmission gears, resulting in cumbersome operation and response delays. With the development and widespread adoption of electric motor drive technology, electronic control schemes based on fixed thresholds have become the industry mainstream: the vehicle controller (VCU) outputs directional commands by comparing the vehicle speed with a preset threshold. Typical logic is as follows: Set forward gear shift speed threshold V F (Negative value) and reverse gear threshold V R (Positive value); When the gear is forward and the vehicle speed V>V F When V is active, output a forward signal; when V is active, output a forward signal. <V R Output a back signal at that time.

[0003] While electronic control improves response speed, fixed threshold settings raise two conflicting technical problems: Commutation shock problem: To reduce mechanical shock during commutation, it is necessary to reduce the mechanical shock during commutation. F | and |V R | Set to a smaller value, such as ±0.5km / h. This is because the smaller the threshold, the lower the system's tolerance for changes in vehicle speed, the smoother the motor torque switching, and the higher the passenger comfort.

[0004] Hill start failure: When a vehicle is in neutral on a slope and then shifts back into drive, if it rolls backward, the vehicle speed V will be negative. In this case, if |V| < V, then the vehicle speed will be negative. F | Too small (e.g., V) F =-0.5km / h), the backward slip speed V=-1km / h will not satisfy V>V F Under certain conditions, the VCU may refuse to send a forward signal, preventing the vehicle from starting and moving forward normally, which could easily lead to safety risks.

[0005] In essence, the shortcomings of fixed threshold systems stem from a lack of scenario adaptability. Specifically, low thresholds are needed to ensure comfort during directional changes, while high thresholds are required to ensure safety during ramp operations. A single parameter cannot accommodate dynamically changing work scenarios. Therefore, there is an urgent need for a driving direction control method that can achieve dynamic threshold setting while ensuring both comfort and safety. Summary of the Invention

[0006] I. Technical problems to be solved This invention provides a method, system, and mechanical device for controlling the driving direction of an electric forklift, which simultaneously achieves low impact during reversing and anti-slippage on ramps by setting a dynamic speed threshold.

[0007] II. Technical Solution In a first aspect, the present invention provides a driving direction control system for an electric forklift, comprising: Signal acquisition unit, control unit, execution unit and display unit; The signal acquisition unit includes a gear shift lever switch and an electronic level, used to acquire gear shift signals and vehicle tilt angle signals; The control unit includes a vehicle controller and a motor controller, and the vehicle controller is communicatively connected to the signal acquisition unit, the display unit, and the motor controller. The execution unit includes a traction motor, which is controlled by the output signal of the motor controller; The vehicle controller is configured as follows: Determine whether the vehicle is in a reversing state based on the edge change of the gear shift signal; Determine whether the vehicle is on a slope by checking if the vehicle body tilt angle signal is greater than the set angle D. When in a reversing state, the first threshold group VF1 and VR1 are used as the direction switching speed thresholds; When in a ramp state, the second threshold group VF2 and VR2 are used as the direction switching speed thresholds, and |VF2|>|VF1|, |VR2|>|VR1|. When neither in a reversing state nor in a ramp state, the third threshold group VF3 and VR3 are used as the direction switching speed thresholds in this default state.

[0008] Preferably, the commutation state includes: Switch to forward direction state: Triggered when the falling edge of the neutral signal on the gear lever and the rising edge of the forward gear signal are detected; Switch to reverse direction: Triggered when the falling edge of the neutral signal on the gear lever and the rising edge of the reverse gear signal are detected.

[0009] Preferably, in the slope state, the vehicle controller subdivides the slope state into multiple sub-states according to the vehicle body tilt angle, and each sub-state corresponds to different VF2 and VR2 values, and the larger the vehicle body tilt angle, the larger the absolute values ​​of VF2 and VR2.

[0010] Preferably, the display unit is configured with the following parameters: VF1 and VR1 in commutation state; VF2 and VR2 in each sub-state of the ramp condition; VF3 and VR3 in their default states; The ramp status trigger angle is D.

[0011] Preferably, the first threshold group satisfies: VF1 is negative and -1km / h≤VF1≤-0.2km / h, VR1 is positive and 0.2km / h≤VR1≤1km / h; The third threshold group satisfies: |VF3|>|VF1| and |VR3|>|VR1|.

[0012] Secondly, the present invention provides a method for controlling the travel direction of an electric forklift, which is applicable to the electric forklift travel direction control system described in the first aspect above, and includes the following steps: S1: Obtain the gear shift signal through the gear lever switch and the vehicle body tilt angle signal through the electronic level. S2: Determine whether to enter the reversing state based on the edge change of the gear shift signal; If so, execute S3: Use the first threshold group VF1 and VR1 as the direction switching speed threshold; If not, execute S4: Determine if the vehicle body tilt angle is greater than the set angle D; If so, execute S5: enter the ramp state and use the second threshold group VF2 and VR2 as the direction switching speed threshold, and satisfy |VF2|>|VF1|, |VR2|>|VR1|; If not, execute S6: Use the third threshold group VF3 and VR3 as the direction switching speed threshold; S7: Generates a direction control signal based on the comparison between the current vehicle speed and the direction switching speed threshold, and controls the operation of the traction motor.

[0013] Preferably, the determination of the commutation state in step S2 includes: When the falling edge of the neutral signal and the rising edge of the forward gear signal are detected, it is determined that the gear lever has been switched to the forward direction. When the falling edge of the neutral signal and the rising edge of the reverse gear signal are detected on the gear lever, it is determined that the gear has switched to the reverse direction.

[0014] Preferably, in step S5, the values ​​of VF2 and VR2 are further selected according to the vehicle body tilt angle, wherein for every 5° increase in the vehicle body tilt angle, the absolute values ​​of VF2 and VR2 increase by 1 km / h.

[0015] Preferably, the first threshold group satisfies: VF1 = -0.5 km / h, VR1 = 0.5 km / h; The third threshold group satisfies: VF3 = -3 km / h, VR3 = 3 km / h.

[0016] Thirdly, the present invention also provides a mechanical device equipped with an electric forklift driving direction control system as described in the first aspect.

[0017] III. Beneficial Effects This invention achieves compatibility between low-impact reversal and anti-rollback on slopes for the first time by dynamically setting the direction switching speed threshold. Specifically, a small absolute value threshold group is used in the reversal state to narrow the tolerance range of vehicle speed judgment, make the motor torque switching smoother, and reduce the reversal impact force; a large absolute value threshold group is used in the slope state to greatly improve the tolerance of backward roll speed, thereby increasing the success rate of starting on slopes.

[0018] Furthermore, this invention employs a slope-based threshold dynamic adjustment strategy, enabling a significant upgrade in the system's adaptability to complex working conditions. Within a slope range of 5°-20°, the system automatically matches the optimal threshold, avoiding the lag of manual switching. For heavy-load steep slope conditions, such as inclination angles >15°, |VF2| can be extended to 4km / h, effectively suppressing the risk of slippage under heavy loads.

[0019] Most importantly, this invention requires no new hardware and can directly reuse existing vehicle sensors, such as electronic levels, gear switches, and controllers, achieving functionality solely through software algorithm upgrades. Furthermore, the display serves as a parameter configuration interface, supporting on-site debugging and adapting to the load and road condition requirements of different vehicle models. This means that this invention can be seamlessly transferred to industrial vehicles such as electric forklifts and tractor units, driving the upgrading of industry safety standards. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the driving direction control system of the present invention.

[0021] Figure 2 This is a schematic diagram of the electrical control principle of the driving direction control system of the present invention.

[0022] Figure 3 This is a flowchart illustrating the control process during the commutation state of the present invention.

[0023] Figure 4 This is a flowchart illustrating the control process under ramp conditions according to the present invention.

[0024] Figure 5 This is a control flowchart for distinguishing between the commutation state and the default state in this invention.

[0025] Figure 6 The control flowchart for distinguishing between reversing state and ramp state in this invention is shown below. Detailed Implementation

[0026] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0027] Example 1: like Figure 1 and Figure 2 As shown, this embodiment provides a driving direction control system for an electric forklift. This system can dynamically adjust the direction switching speed threshold according to different driving states of the vehicle, thereby achieving precise control of the vehicle's driving direction and improving driving safety and comfort. The system consists of a signal acquisition unit, a control unit, an execution unit, and a display unit, all connected via a CAN bus.

[0028] Optionally, the signal acquisition unit includes a gear shift lever switch and an electronic level. The gear shift lever switch is installed on the steering gear inside the driver's cab and has three positions: N (neutral), R (reverse), and F (drive). It is used to acquire the driver's operation signals and is connected to the vehicle controller via a hardwired connection, enabling real-time transmission of gear shift signals to the vehicle controller. The electronic level is installed at the center of the longitudinal beam of the chassis and is used to measure the vehicle body tilt angle. It is connected to the vehicle controller via a bus and sends the vehicle body tilt angle signal to the controller at a millisecond frequency.

[0029] The control unit includes a vehicle controller and a motor controller. The vehicle controller is hardwired to the gear shift lever switch, receives gear shift signals, and communicates with the electronic level via a bus to obtain the vehicle body tilt angle signal. Simultaneously, the vehicle controller interacts with the motor controller via a CAN bus, sending direction control signals to the motor controller. The motor controller can precisely control the operation of the traction motor according to the instructions from the vehicle controller.

[0030] The actuator is a traction motor, mounted on the drive axle of the forklift and connected to the wheels via a drive shaft. The traction motor is controlled by the output signal of the motor controller, enabling rapid and smooth switching between forward and reverse rotation, thereby driving the forklift forward and backward.

[0031] The display unit is a touch-screen LCD monitor installed in the driver's cab, facilitating parameter configuration and vehicle status viewing for the driver. It connects to the vehicle controller via a CAN bus and displays configuration parameters such as VF1 and VR1 in reversing mode, VF2 and VR2 in various sub-states of ramp mode, VF3 and VR3 in default mode, and ramp trigger angle D to the driver. It also transmits the driver's settings to the vehicle controller in real time.

[0032] Specifically, the system first determines whether the vehicle is in a reversing state based on the edge changes of the gear shift signal. When a falling edge of the neutral signal and a rising edge of the forward gear signal are detected within ±50ms, the forklift is determined to have switched to the forward direction; when a falling edge of the neutral signal and a rising edge of the reverse gear signal are detected within ±50ms, the forklift is determined to have switched to the reverse direction.

[0033] Secondly, based on whether the vehicle tilt angle signal is greater than a set angle D, in this embodiment, D=5° is set to determine whether the vehicle is on a slope. If it is in a reversing state, the first threshold group VF1 and VR1 are used as the direction switching speed thresholds, where VF1 is -0.5km / h and VR1 is 0.5km / h. If it is on a slope, the second threshold group VF2 and VR2 are used as the direction switching speed thresholds, and |VF2|>|VF1|, |VR2|>|VR1| are satisfied. When the tilt angle is <5° and there is no reversing operation, the default state is entered. For example, when the vehicle tilt angle is 6°, VF2 is set to -2km / h and VR2 is set to 2km / h; when the vehicle tilt angle increases to 10°, VF2 is set to -3km / h and VR2 is set to 3km / h. If the vehicle is neither in a reversing state nor on a ramp, then the third threshold group VF3 and VR3 are used as the default direction switching speed thresholds, with VF3 being -3km / h and VR3 being 3km / h.

[0034] Optionally, the vehicle controller compares the vehicle body tilt angle signal with a set angle D=5° to determine whether the vehicle is on a slope. When the vehicle body tilt angle is greater than or equal to 5°, it is determined to be on a slope, and the slope state is further subdivided into multiple sub-states based on the magnitude of the vehicle body tilt angle.

[0035] The specific sub-state divisions are as follows: Slope condition 1: When the vehicle body tilt angle is within the range of [5°, 10°), the corresponding second threshold group VF2 is -2km / h and VR2 is 2km / h; Slope condition 2: When the vehicle body tilt angle is within the range of [10°, 15°), the corresponding second threshold group VF2 is -3km / h and VR2 is 3km / h; Slope condition 3: The vehicle body tilt angle is within the range of [15°, 20°), and the corresponding second threshold group VF2 is -4km / h and VR2 is 4km / h.

[0036] As the vehicle body tilt angle increases, the absolute values ​​of VF2 and VR2 gradually increase, which can adapt to the driving needs of the vehicle under different slopes.

[0037] During operation, the vehicle controller receives gear shift signals and vehicle tilt angle signals in real time, and determines the vehicle's state based on preset logic, thereby selecting the corresponding speed threshold. For example, when the forklift is traveling on level ground, and the driver shifts the gear lever from neutral to drive, the vehicle controller detects the falling edge of the neutral signal and the rising edge of the drive signal, determining it to be a reversing state. In this case, VF1 and VR1 are used as speed thresholds. If the current vehicle speed V is greater than or equal to VF1, the vehicle controller sends a forward direction signal to the motor controller, and the traction motor drives the forklift forward; if the current vehicle speed V is less than VR1, it sends a reverse direction signal, and the traction motor drives the forklift backward. As another example, when the forklift is parked on an 8° slope, and the driver shifts from neutral to drive, the vehicle controller determines it is on a slope based on the electronic level signal. In this case, the corresponding VF2 and VR2 are used as speed thresholds. Since starting on a slope may result in rollback, a larger speed threshold effectively avoids the problem of not being able to shift to drive due to the vehicle speed V rolling back to less than VF2, ensuring a smooth start for the vehicle.

[0038] The aforementioned speed thresholds and ramp trigger angle D, among other parameters, can all be flexibly configured via the display unit. Manufacturers set a set of default values ​​based on the forklift model and performance parameters at the factory. These default values ​​have been rigorously tested and verified to meet the needs of most working conditions. However, for specific working environments or individual user requirements, drivers can adjust these parameters via the display unit. For example, in warehouse environments where high stability is crucial, drivers can appropriately reduce the absolute values ​​of VF1 and VR1; while in construction site environments where steep slopes are frequently required, the values ​​of VF2 and VR2 under ramp conditions can be appropriately increased to adapt to different working conditions.

[0039] Example 2: like Figures 2 to 6 As shown, this embodiment provides a control method based on the electric forklift driving direction control system described in Embodiment 1 above.

[0040] Specifically, S1: The gear shift signal is obtained through the gear shift lever switch, and the vehicle body tilt angle signal is obtained through the electronic level. The gear shift lever switch monitors the driver's gear operation in real time and transmits the corresponding electrical signal to the vehicle controller; the electronic level continuously measures the vehicle body tilt angle and sends the angle signal to the vehicle controller via the bus.

[0041] S2: The vehicle controller determines whether to enter the reversing state based on the edge change of the gear shift signal. The specific judgment logic is as follows: detect whether the neutral signal of the gear lever has a falling edge, and at the same time detect whether the forward or reverse gear signal has a rising edge. If so, enter the reversing state and execute step S3; otherwise, execute step S4.

[0042] S3: When in a reversing state, the vehicle controller uses the first threshold group VF1 and VR1 as the direction switching speed thresholds. VF1 is negative and -1km / h ≤ VF1 ≤ -0.2km / h, while VR1 is positive and 0.2km / h ≤ VR1 ≤ 1km / h. For example, if VF1 is set to -0.5km / h and VR1 to 0.5km / h, when the current vehicle speed V is greater than or equal to VF1, the vehicle controller determines it as a forward direction; when the current vehicle speed V is less than VR1, it determines it as a reverse direction.

[0043] S4: If not in a reversing state, the vehicle controller determines whether the vehicle body tilt angle is greater than the set angle D=5°. If yes, proceed to step S5; otherwise, proceed to step S6.

[0044] S5: Entering the ramp state, and using the second threshold group VF2 and VR2 as the direction switching speed thresholds, satisfying |VF2|>|VF1|, |VR2|>|VR1|. The vehicle controller selects the corresponding VF2 and VR2 values ​​according to the vehicle tilt angle. For example, for every 5° increase in vehicle tilt angle, the absolute values ​​of VF2 and VR2 increase by 1 km / h. When the vehicle tilt angle is 5°, VF2 is -2 km / h and VR2 is 2 km / h; when the vehicle tilt angle is 10°, VF2 is -3 km / h and VR2 is 3 km / h.

[0045] S6: When neither in a reversing state nor on a ramp, the third threshold group VF3 and VR3 are used as the direction switching speed thresholds, and |VF3|>|VF1| and |VR3|>|VR1| are satisfied. For example, VF3 is set to -3km / h and VR3 is set to 3km / h.

[0046] S7: The vehicle controller generates a direction control signal and sends it to the motor controller by comparing the vehicle speed calculated from the motor speed fed back by the current motor controller with the selected direction switching speed threshold (VF1 and VR1, VF2 and VR2, or VF3 and VR3). The motor controller then controls the traction motor to rotate forward or backward according to the received direction control signal, thereby enabling the vehicle to move forward or backward.

[0047] In practical operation, this control method can respond quickly based on the vehicle's real-time status. For example, when the forklift is traveling on level ground and the driver suddenly shifts the gear lever from forward to reverse, the vehicle controller quickly detects the edge change of the gear shift signal, determines that a reversing state has been entered, and immediately uses VF1 and VR1 as speed thresholds for direction determination, ensuring a smooth transition during the reversing process and avoiding shocks caused by excessively rapid speed changes. As another example, when the forklift is traveling on a gradually increasing slope, the vehicle controller, based on changes in the vehicle's tilt angle detected by the electronic level, promptly switches to the corresponding slope state and adjusts the speed thresholds to ensure the stability and safety of the vehicle while traveling on the slope.

[0048] Example 3: This embodiment also provides a mechanical device equipped with the electric forklift driving direction control system described in Embodiment 1 above. This mechanical device can be a common industrial vehicle such as a stacker. It is understood that the implementation methods of the direction control system and control method of this mechanical device can refer to Embodiments 1 and 2 above, and will not be repeated in this embodiment.

[0049] In summary, the electric forklift driving direction control system and its control method provided by this invention, by dynamically adjusting the direction switching speed threshold, fully consider the vehicle's needs under different driving conditions, effectively improving the forklift's driving comfort and safety. At the same time, the system's intelligent design and human-machine interaction functions improve the forklift's ease of use and maintainability, possessing broad market application prospects and significant economic benefits.

Claims

1. An electric forklift travel direction control system, characterized in that, include: Signal acquisition unit, control unit, execution unit and display unit; The signal acquisition unit includes a gear shift lever switch and an electronic level, used to acquire gear shift signals and vehicle tilt angle signals; The control unit includes a vehicle controller and a motor controller, and the vehicle controller is communicatively connected to the signal acquisition unit, the display unit, and the motor controller. The execution unit includes a traction motor, which is controlled by the output signal of the motor controller; The vehicle controller is configured as follows: Determine whether the vehicle is in a reversing state based on the edge change of the gear shift signal; Determine whether the vehicle is on a slope by checking if the vehicle body tilt angle signal is greater than the set angle D. When in a reversing state, the first threshold group VF1 and VR1 are used as the direction switching speed thresholds; When in a ramp state, the second threshold group VF2 and VR2 are used as the direction switching speed thresholds, and |VF2|>|VF1|, |VR2|>|VR1|. When neither in a reversing state nor in a ramp state, the third threshold group VF3 and VR3 are used as the direction switching speed thresholds in this default state.

2. The electric forklift driving direction control system according to claim 1, characterized in that, The commutation state includes: Switch to forward direction state: Triggered when the falling edge of the neutral signal on the gear lever and the rising edge of the forward gear signal are detected; Switch to reverse direction: Triggered when the falling edge of the neutral signal on the gear lever and the rising edge of the reverse gear signal are detected.

3. The electric forklift driving direction control system according to claim 1, characterized in that: In the slope state, the vehicle controller subdivides the slope state into multiple sub-states according to the vehicle body tilt angle. Each sub-state corresponds to different VF2 and VR2 values, and the larger the vehicle body tilt angle, the larger the absolute values ​​of VF2 and VR2.

4. The electric forklift driving direction control system according to claim 1, characterized in that, The display unit is used to configure the following parameters: VF1 and VR1 in commutation state; VF2 and VR2 in each sub-state of the ramp condition; VF3 and VR3 in their default states; The ramp status trigger angle is D.

5. The electric forklift travel direction control system according to claim 1, characterized in that: The first threshold group satisfies: VF1 is negative and -1km / h≤VF1≤-0.2km / h, VR1 is positive and 0.2km / h≤VR1≤1km / h; the third threshold group satisfies: |VF3|>|VF1| and |VR3|>|VR1|.

6. A control method for the electric forklift travel direction control system according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1: Obtain the gear shift signal through the gear lever switch and the vehicle body tilt angle signal through the electronic level. S2: Determine whether to enter the reversing state based on the edge change of the gear shift signal; If so, execute S3: Use the first threshold group VF1 and VR1 as the direction switching speed threshold; If not, execute S4: Determine if the vehicle body tilt angle is greater than the set angle D; If so, execute S5: enter the ramp state and use the second threshold group VF2 and VR2 as the direction switching speed threshold, and satisfy |VF2|>|VF1|, |VR2|>|VR1|; If not, execute S6: Use the third threshold group VF3 and VR3 as the direction switching speed threshold; S7: Generates a direction control signal based on the comparison between the current vehicle speed and the direction switching speed threshold, and controls the operation of the traction motor.

7. The electric forklift driving direction control method according to claim 6, characterized in that: The determination of the commutation state in step S2 includes: When the falling edge of the neutral signal and the rising edge of the forward gear signal are detected, it is determined that the gear lever has been switched to the forward direction. When the falling edge of the neutral signal and the rising edge of the reverse gear signal are detected on the gear lever, it is determined that the gear has switched to the reverse direction.

8. The electric forklift driving direction control method according to claim 6, characterized in that: In step S5, the values ​​of VF2 and VR2 are further selected based on the vehicle body tilt angle. For every 5° increase in vehicle body tilt angle, the absolute values ​​of VF2 and VR2 increase by 1 km / h.

9. The electric forklift driving direction control method according to claim 6, characterized in that: The first threshold group satisfies: VF1 = -0.5 km / h, VR1 = 0.5 km / h; the third threshold group satisfies: VF3 = -3 km / h, VR3 = 3 km / h.

10. Mechanical equipment, characterized in that, The electric forklift is equipped with a driving direction control system as described in any one of claims 1-5.

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