Electric forklift driving direction control method and system and mechanical equipment

Abstract

The invention relates to the field of industrial vehicle control, in particular to a forklift driving direction control method and system and mechanical equipment. The system comprises a signal acquisition unit, a control unit, an execution unit and a display unit. And a gear handle switch and an electronic level meter of the signal acquisition unit respectively acquire a gear signal and a vehicle body inclination angle signal. A vehicle controller and a motor controller of the control unit dynamically adjust direction switching speed threshold values according to the signals and preset logic, a first threshold value group is adopted during reversing, a second threshold value group is adopted during rampway, and a third threshold value group is adopted under other conditions. A traction motor of the execution unit adjusts the steering direction according to signals of a motor controller. The display unit can be configured with parameters such as a speed threshold value and a ramp triggering angle. According to the control method, the speed threshold value is dynamically adjusted by detecting gear signals and the vehicle body inclination angle, and direction control is achieved. The problems that in the prior art, due to the fact that the speed set value is fixed, reversing impact is large, and hill starting is difficult are solved, and the driving comfort and safety are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of industrial vehicle control, in particular to a driving direction control system and method of an electric forklift based on dynamic adjustment of direction switching speed threshold, which is suitable for electric forklifts, stackers and other mechanical equipment that require precise direction control. BACKGROUND

[0002] As the core equipment of modern logistics, the driving direction control technology of electric forklifts has experienced an upgrading process from mechanical linkage to electronic control. The early control scheme (such as gear shift fork linkage mechanism) relies on physical shift lever to directly switch the transmission gear, which has problems such as cumbersome operation and delayed response. With the development and popularization of motor drive technology, the electronic control scheme based on fixed threshold has become the industry mainstream: the vehicle controller (VCU) outputs the direction instruction by comparing the vehicle speed with the preset threshold. The typical logic is as follows: Set the forward gear switching speed threshold V F (negative value) and the reverse gear threshold V R (positive value); When the gear is forward and the speed V>V F , output forward signal; when V<V R , output reverse signal.

[0003] Although electronic control improves the response speed, the fixed threshold setting causes two contradictory technical problems: The problem of reverse impact: in order to reduce the mechanical impact during switching, ∣V F ∣ and ∣V R ∣ are set to small values, such as ±0.5km / h. Because the smaller the threshold value, the lower the tolerance of the system to speed changes, the smoother the motor torque switching, and the higher the passenger comfort.

[0004] Slope starting failure: when the vehicle is in neutral gear on the slope and then switches to forward gear, if it slips backward, the vehicle speed V is negative. At this time, if ∣V F ∣ is too small (for example, V F =-0.5km / h), the slip speed V=-1km / h will not meet the condition V>V F , causing the VCU to refuse to issue a forward signal, the vehicle cannot start and move forward normally, and safety risks are easily caused.

[0005] In essence, the defect of the fixed threshold system is due to the lack of scene adaptability, that is, the switching condition requires a small threshold to ensure comfort, and the slope condition requires a large threshold to ensure safety, and a single parameter cannot be compatible with dynamic and variable working conditions. Therefore, there is an urgent need for a driving direction control method that can realize dynamic threshold setting and ensure comfort and safety. SUMMARY

[0006] I. Technical problems solved The application provides an electric forklift driving direction control method, system and mechanical equipment, which realizes low-impact reversing and slope anti-sliding through dynamic speed threshold setting.

[0007] II. Technical solutions In a first aspect, the application provides an electric forklift driving direction control system, comprising: a signal acquisition unit, a control unit, an execution unit and a display unit; The signal acquisition unit comprises a gear handle switch and an electronic level, and is configured to acquire gear switching signals and vehicle body inclination angle signals. The control unit comprises a vehicle controller and a motor controller, wherein the vehicle controller is in communication connection with the signal acquisition unit, the display unit and the motor controller. The execution unit comprises a traction motor, which is controlled by the output signal of the motor controller. The vehicle controller is configured to: determine whether the vehicle is in a reversing state according to the edge change of the gear switching signal; determine whether the vehicle is in a slope state according to whether the vehicle body inclination angle signal is greater than a set angle D; when the vehicle is in the reversing state, a first threshold group VF1 and VR1 is used as the direction switching speed threshold; when the vehicle is in the slope state, a second threshold group VF2 and VR2 is used as the direction switching speed threshold, and |VF2|>|VF1| and |VR2|>|VR1| are satisfied; when the vehicle is neither in the reversing state nor in the slope state, a third threshold group VF3 and VR3 is used as the direction switching speed threshold in the default state.

[0008] Preferably, the reversing state comprises: switching to a forward direction state: triggered when the gear handle neutral signal falling edge and the forward gear signal rising edge are detected; switching to a backward direction state: triggered when the gear handle neutral signal falling edge and the backward gear signal rising edge are detected.

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

[0010] Preferably, the display unit is configured to configure the following parameters: VF1 and VR1 in the reversing state; VF2 and VR2 in each sub-state in the slope state. VF3, VR3 in the default state; D, the trigger angle of the ramp state.

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

[0012] In a second aspect, the present application provides a driving direction control method of an electric forklift, which is applicable to the electric forklift driving direction control system of the first aspect, and comprises the following steps: S1: obtaining a gear switching signal through a gear handle switch and obtaining a vehicle body inclination angle signal through an electronic level; S2: judging whether to enter a reversing state according to the edge change of the gear switching signal; If yes, performing S3: using the first threshold group VF1 and VR1 as the direction switching speed threshold; If no, performing S4: judging whether the vehicle body inclination angle is greater than a set angle D; If yes, performing S5: entering a ramp state and using the second threshold group VF2 and VR2 as the direction switching speed threshold, and satisfying |VF2|>|VF1| and |VR2|>|VR1|; If no, performing S6: using the third threshold group VF3 and VR3 as the direction switching speed threshold; S7: generating a direction control signal according to the comparison result of the current vehicle speed and the direction switching speed threshold, and controlling the traction motor to operate.

[0013] Preferably, the judgment of the reversing state in step S2 comprises: when the gear handle neutral signal falling edge and the forward gear signal rising edge are detected, it is determined that the direction is switched to the forward direction state; when the gear handle neutral signal falling edge and the reverse gear signal rising edge are detected, it is determined that the direction is switched to the reverse direction state.

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

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

[0016] In a third aspect, the present application also provides a mechanical device, which is installed with the electric forklift driving direction control system as described in the first aspect.

[0017] III. Advantages The present application realizes the compatibility of reversing low impact and slope anti-slip by dynamically setting the direction switching speed threshold, specifically, in the reversing state, a small absolute value threshold group is used, which narrows the speed judgment tolerance range, and the motor torque switching is more gentle, reducing the reversing impact force; in the slope state, a large absolute value threshold group is enabled, which greatly improves the inclusiveness of the rear slip speed, and the slope starting success rate is improved.

[0018] Further, the present application is based on the threshold dynamic adjustment strategy based on slope grading, which makes the system adapt to complex working conditions in a leapfrog manner. In the 5°-20° slope range, the system automatically matches the optimal threshold to avoid the hysteresis of manual switching; for heavy load steep slope conditions, such as an angle > 15°, |VF2| can be extended to 4km / h, effectively inhibiting the risk of heavy load slip.

[0019] What is particularly important is that the present application does not need to add new hardware, and can directly reuse the existing sensors of the vehicle, such as the electronic level meter, gear switch and controller, and only needs to upgrade the function through the software algorithm; and the display as a parameter configuration interface supports on-site debugging, and adapts to the load and road condition requirements of different vehicle models. This means that the present application can be seamlessly migrated to electric stackers, tractors and other industrial vehicles, and promote the upgrading of industry safety standards. BRIEF DESCRIPTION OF DRAWINGS

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

[0021] Figure 2 It is an electric control principle diagram of the driving direction control system of the present application.

[0022] Figure 3 It is a control flowchart in the reversing state of the present application.

[0023] Figure 4 It is a control flowchart in the slope state of the present application.

[0024] Figure 5 It is a control flowchart for distinguishing the reversing state and the default state of the present application.

[0025] Figure 6 It is a control flowchart for distinguishing the reversing state and the slope state of the present application. DETAILED DESCRIPTION

[0026] The application will be described in detail below with specific examples. The following examples will help those skilled in the art to further understand the application, but do not limit the application in any form. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the application. These are within the scope of protection of the application.

[0027] Example 1 As shown in Figure 1 and Figure 2 , the embodiment provides a driving direction control system for electric forklifts. The system can dynamically adjust the direction switching speed threshold according to different driving states of the vehicle, thereby achieving precise control of the driving direction of the vehicle and improving the safety and comfort of driving. The system consists of a signal acquisition unit, a control unit, an execution unit, and a display unit, which are connected through a CAN bus.

[0028] Optionally, the signal acquisition unit includes a gear handle switch and an electronic level. The gear handle switch is installed on the steering machine inside the cab and has three gears: N (neutral), R (reverse), and F (forward), which are used to collect the operator's operation signals. It is connected to the vehicle controller through a hard wire and can transmit the gear switching signals to the vehicle controller in real time. The electronic level is installed at the center of the vehicle frame longitudinal beam to measure the inclination angle of the vehicle body. It is connected to the vehicle controller through a bus and sends the vehicle body inclination angle signal to the controller at a millisecond level.

[0029] The control unit includes a vehicle controller and a motor controller. The vehicle controller is connected to the gear handle switch through a hard wire and receives the gear switching signal. It communicates with the electronic level through a bus and obtains the vehicle body inclination angle signal. At the same time, the vehicle controller exchanges data with the motor controller through a CAN bus and sends the direction control signal to the motor controller. The motor controller can accurately control the operation of the traction motor according to the instructions of the vehicle controller.

[0030] The execution unit is a traction motor installed on the drive axle of the forklift and connected to the wheels through a transmission shaft. The traction motor is controlled by the output signal of the motor controller and can realize fast and smooth forward and reverse switching to drive the forklift forward and backward.

[0031] The display unit is a touch liquid crystal display installed in the cab for the driver to configure parameters and view the vehicle status. It is connected to the vehicle controller through a CAN bus and can display the configuration interface of VF1, VR1 in the reversing state, VF2, VR2 in each sub-state of the ramp state, VF3, VR3 in the default state, and the ramp state trigger angle D to the driver. The driver's setting parameters are transmitted to the vehicle controller in real time.

[0032] Specifically, the vehicle is determined to be in the reversing state according to the edge change of the gear shift signal. When the gear handle neutral signal falling edge and the forward gear signal rising edge are detected within ±50 ms, the forklift is determined to switch to the forward direction state; when the gear handle neutral signal falling edge and the reverse gear signal rising edge are detected within ±50 ms, the forklift is determined to switch to the reverse direction state.

[0033] Secondly, the vehicle is determined to be in the slope state according to whether the vehicle body inclination signal is greater than the set angle D, which is set to 5° in this embodiment. If the vehicle is in the reversing state, the first threshold group VF1 and VR1 are used as the direction switching speed threshold, wherein VF1 is -0.5 km / h and VR1 is 0.5 km / h. If the vehicle is in the slope state, the second threshold group VF2 and VR2 are used as the direction switching speed threshold, and |VF2|>|VF1| and |VR2|>|VR1| are satisfied. When the inclination is less than 5° and there is no reversing operation, the default state is entered. For example, when the vehicle body inclination is 6°, VF2 is set to -2 km / h and VR2 is set to 2 km / h; when the vehicle body inclination increases to 10°, VF2 is set to -3 km / h and VR2 is set to 3 km / h. If the vehicle is neither in the reversing state nor in the slope state, the third threshold group VF3 and VR3 are used as the direction switching speed threshold in the default state, wherein VF3 is -3 km / h and VR3 is 3 km / h.

[0034] Alternatively, the vehicle controller compares the vehicle body inclination signal with the set angle D=5° to determine whether the vehicle is in the slope state. When the vehicle body inclination is greater than or equal to 5°, the slope state is determined, and the slope state is further subdivided into multiple sub-states according to the size of the vehicle body inclination.

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

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

[0037] During operation, the vehicle controller receives real-time gear shift signals and body tilt angle signals, and based on pre-set logic, determines the vehicle's current state and selects the appropriate speed threshold. For example, when a forklift is traveling on flat ground and the driver shifts the shift lever from neutral to forward, the vehicle controller detects the falling edge of the neutral signal and the rising edge of the forward gear signal, identifying a direction change. 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, causing the traction motor to drive the forklift forward. If the current vehicle speed V is less than VR1, a reverse direction signal is sent, causing the traction motor to drive the forklift backward. For another example, when a forklift is parked on an 8° slope and the driver shifts from neutral to forward, the vehicle controller determines the vehicle is on a slope based on the signal from the electronic level gauge. In this case, VF2 and VR2 are used as speed thresholds. Since starting on a slope can result in the vehicle rolling away, a larger speed threshold effectively prevents the vehicle from being unable to shift into forward gear due to a speed V less than VF2, ensuring a smooth vehicle start.

[0038] The aforementioned speed thresholds, as well as parameters such as the ramp trigger angle D, can be flexibly configured through 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 verified through extensive experimentation and meet the requirements of most operating conditions. However, for specialized working environments or individual user needs, the driver can adjust these parameters through the display unit. For example, in warehouse environments where driving smoothness is extremely important, the driver can appropriately reduce the absolute values ​​of VF1 and VR1. On construction sites where operations on steep slopes are common, the VF2 and VR2 values ​​in the ramp state can be appropriately increased to accommodate different working conditions.

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

[0040] Specifically, S1: Receives a gear shift signal from the gear lever switch and a vehicle body tilt angle signal from the electronic level. The gear lever switch monitors the driver's gear position 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 to detect whether the neutral signal of the gear lever has a falling edge, and simultaneously detect whether the forward gear signal or the reverse gear signal has a rising edge. If so, the reversing state is entered and step S3 is executed; otherwise, step S4 is executed.

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

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

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

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

[0046] S7: The vehicle controller generates a direction control signal according to the comparison result of the vehicle speed converted from the motor speed feedback of the current motor controller and the selected direction switching speed threshold (VF1 and VR1, VF2 and VR2, or VF3 and VR3), and sends it to the motor controller. The motor controller controls the forward or reverse rotation of the traction motor according to the received direction control signal, thereby realizing the forward or reverse movement of the vehicle.

[0047] In actual work process, the control method can quickly respond according to the real-time state of the vehicle. For example, when the forklift is driving on the flat ground, the driver suddenly switches the gear handle from forward gear to reverse gear, the vehicle controller quickly detects the edge change of the gear switching signal, determines to enter the reversing state, immediately uses VF1 and VR1 as the speed threshold for direction judgment, ensures the smooth transition of the vehicle in the reversing process, and avoids the impact caused by the too fast speed change. For another example, when the forklift is driving on the slope with gradually increasing slope, the vehicle controller switches to the corresponding slope state in time according to the change of the body inclination angle detected by the electronic level, and adjusts the speed threshold, to ensure the stability and safety of the vehicle when driving on the slope.

[0048] Embodiment three: The embodiment also provides a mechanical equipment, which is installed with the electric forklift driving direction control system of the above-mentioned embodiment one. The mechanical equipment can be a common industrial vehicle such as a stacker. It can be understood that the implementation of the direction control system and the control method of the mechanical equipment can refer to the above-mentioned embodiment one and embodiment two, and will not be described here in this embodiment.

[0049] In summary, the electric forklift driving direction control system and the control method thereof provided by the present application fully consider the vehicle demand under different driving states by dynamically adjusting the direction switching speed threshold, effectively improve the driving comfort and safety of the forklift. At the same time, the intelligent design and human-computer interaction function of the system improve the usability and maintainability of the forklift, and have broad market application prospect and significant economic benefits.

Claims

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

2. The electric forklift driving direction control system according to claim 1, characterized in that: The switching state includes: Switch to forward direction state: triggered when the falling edge of the neutral signal of the gear handle and the rising edge of the forward gear signal are detected; Switch to the reverse direction state: triggered when the falling edge of the neutral signal of the gear handle 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 ramp state, the vehicle controller subdivides the ramp state into multiple sub-states according to the body inclination angle. Each sub-state corresponds to a different VF2 and VR2 value. The greater the body inclination angle, the greater 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 the reversing state; VF2 and VR2 in each sub-state of the ramp state; VF3 and VR3 in default state; Slope state trigger angle D.

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

6. The control method of the electric forklift driving direction control system according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: obtains the gear shift signal through the gear handle switch and the vehicle body inclination signal through the electronic level; S2: Determine whether to enter the reversing state according to the edge change of the gear switching signal; If yes, execute S3: adopt the first threshold value group VF1 and VR1 as the direction switching speed threshold; If not, execute S4: determine whether the vehicle body tilt angle is greater than the set angle D; If yes, execute S5: enter the ramp state and use the second threshold value group VF2 and VR2 as the direction switching speed threshold, and satisfy |VF2|>|VF1|, |VR2|>|VR1|; If not, execute S6: adopt the third threshold value group VF3 and VR3 as the direction switching speed threshold; S7: Generate a direction control signal based on the comparison result between the current vehicle speed and the direction switching speed threshold to control the operation of the traction motor.

7. The method for controlling the driving direction of an electric forklift according to claim 6, wherein: The determination of the commutation state in step S2 includes: When the falling edge of the neutral position signal of the gear lever and the rising edge of the forward gear position signal are detected, it is determined to be switched to the forward direction state; When the falling edge of the neutral position signal of the shift handle and the rising edge of the reverse position signal are detected, it is determined to be switched to the reverse direction state.

8. The method for controlling the driving direction of an electric forklift according to claim 6, wherein: In step S5, the values ​​of VF2 and VR2 are further selected according to the magnitude of the vehicle body inclination angle, wherein the absolute values ​​of VF2 and VR2 increase by 1 km / h for every 5° increase in the vehicle body inclination angle.

9. The method for controlling the driving direction of an electric forklift according to claim 6, wherein: The first threshold value group satisfies: VF1=-0.5km / h, VR1=0.5km / h; the third threshold value group satisfies: VF3=-3km / h, VR3=3km / h.

10. Mechanical equipment, characterized in that An electric forklift driving direction control system according to any one of claims 1 to 5 is installed.

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