Four-motor pure electric land leveler driving system and driving control method

Abstract

The invention relates to the field of land levelers, and particularly discloses a four-motor pure electric land leveler driving system and a driving control method.The four-motor pure electric land leveler driving system comprises four electric driving mechanisms, each electric driving mechanism is connected with a wheel, each wheel is provided with a rotating speed sensor for detecting the rotating speed of the wheel, and each rotating speed sensor is electrically connected with a main controller; the main controller is electrically connected with each electric driving mechanism; the main controller controls the vehicles on the two sides to operate synchronously through the electric driving mechanism according to the rotating speed of each wheel. The rotating speed of each wheel is allowed to be independently controlled, so that more accurate driving force adjustment is provided, wheel synchronization is guaranteed, and stability and working efficiency are improved.

Description

Technical Field

[0001] The present invention relates to the field of motor graders, and in particular to a four-motor pure electric motor grader drive system and a drive control method. Background Art

[0002] In today's rapidly changing technological field, pure electric motor graders, as an important member of construction machinery, have shown great potential in environmental protection and energy conservation with their advantages such as zero emissions, low noise and high efficiency.

[0003] Pure electric graders mainly use motor drive to achieve their motion functions. However, related technologies generally use a single motor to drive the grader vehicle, that is, one drive motor is used to control four vehicles through the drive axle. This single motor drive method may lead to uneven distribution of driving force, affecting operating efficiency and machine stability. Especially on uneven or complex terrain, traditional graders are difficult to maintain a constant and synchronous speed, affecting work performance and safety. Summary of the invention

[0004] To solve the above problems, the present invention provides a four-motor pure electric grader drive system and drive control method, which allows independent control of the speed of each wheel, thereby providing more precise driving force adjustment, ensuring wheel synchronization, and improving stability and work efficiency.

[0005] In a first aspect, the technical solution of the present invention provides a four-motor pure electric grader drive system, including four electric drive mechanisms, each of which is connected to a wheel, and a speed sensor for detecting the wheel speed is installed at each wheel, each speed sensor is electrically connected to a main controller, and the main controller is electrically connected to each electric drive mechanism; the main controller controls the synchronous operation of the vehicles on both sides through the electric drive mechanisms according to the speed of each wheel.

[0006] In an optional embodiment, the electric drive mechanism includes a drive motor, a reducer and a motor drive controller. The output end of the motor is connected to the wheel through the reducer, the drive motor is electrically connected to the motor drive controller, and the motor drive controller is electrically connected to the main controller. The motor drive controller adjusts the drive motor current according to the instructions of the main controller to control the synchronous operation of the vehicles on both sides.

[0007] In an optional embodiment, it also includes a power battery for supplying power to each electric drive mechanism, and the power battery is equipped with an external charging interface.

[0008] In an optional embodiment, it also includes a steering component connected to the front wheels, the steering component includes a steering motor, a steering pump, a proportional electromagnetic reversing valve and a steering hydraulic cylinder, and a steering hydraulic cylinder position sensor is arranged at the steering hydraulic pump; the steering hydraulic cylinder position sensor and the proportional electromagnetic reversing valve are electrically connected to the main controller respectively; the main controller controls the proportional electromagnetic reversing valve current according to the detection signal of the steering hydraulic cylinder position sensor to control the steering angle of the front wheels.

[0009] In an optional embodiment, the main controller is also used to perform electronic differential steering control according to the actual steering angle when the vehicle turns.

[0010] In a second aspect, the technical solution of the present invention provides a four-motor pure electric grader drive control method, including a synchronous control process, specifically including the following steps: Read the wheel speeds on both sides. The wheel speed on each side is the average of the two wheel speeds on the same side. Detect whether the synchronization control button is activated; If it is not started, the synchronization control will not be executed. If it is started, the next step will be executed; Calculate the difference in wheel speed between the left and right sides; Set a small motor control current adjustment amount, recorded as the first small adjustment amount; Determine whether the difference in wheel speeds on the left and right sides is less than a preset differential threshold; If yes, then end the synchronization control; if no, proceed to the next step; Determine whether the left side has a fast rotation speed; If so, the driving motor current of the left wheel is controlled to decrease by the first adjustment amount, the driving motor current of the right wheel is increased by the first adjustment amount, and the left and right wheel speeds are re-read; otherwise, the driving motor current of the left wheel is controlled to increase by the first adjustment amount, the driving motor current of the right wheel is decreased by the first adjustment amount, and the left and right wheel speeds are re-read.

[0011] In an optional embodiment, a front wheel steering angle control process is also included, which specifically includes the following steps: A small current adjustment amount of the proportional electromagnetic reversing valve is pre-configured and recorded as the second small adjustment amount; Read the wheel speeds on both sides. The wheel speed on each side is the average of the two wheel speeds on the same side. Detect whether the back button is in neutral; If yes, proceed to the next step directly. If no, check whether the wheel speeds on both sides are zero. If yes, proceed to the next step. Otherwise, end. Read the left handle voltage signal U1 and the steering hydraulic cylinder position sensor voltage signal U2; Calculate the desired steering angle θ0 according to the voltage signal U1, and calculate the actual steering angle θ according to the voltage signal U2; Determine whether θ<θ0; If yes, the control current of the left electromagnet of the proportional electromagnetic reversing valve is set to 0, and the control current of the right electromagnet is increased by a second small adjustment amount; If not, determine whether θ>θ0; If yes, the right electromagnet control current of the proportional electromagnetic reversing valve is set to 0, and the left electromagnet control current is increased by a second small adjustment amount; If not, then end.

[0012] In an optional embodiment, an electronic differential steering control process is also included, which specifically includes the following steps: Step 1, reading the actual steering angle θ and the current driving speed of the grader; Step 2, calculate the rear wheel speeds on the left and right sides by the following formula;

[0013] In the formula, is the rear left wheel speed, is the rear right wheel speed, is the front and rear wheelbase, For left and right wheelbase; Step 3, calculating the speed increment of the driving motors of the two rear wheels by the following formula;

[0014]

[0015] In the formula, is the rear left wheel drive motor speed, is the transmission ratio from the rear left wheel drive motor to the rear left wheel, is the rear right wheel drive motor speed, is the transmission ratio from the rear right wheel drive motor to the rear right wheel, is the wheel circumference; Step 4: Output instructions to the drive motors of the left and right wheels.

[0016] A four-motor pure electric grader drive system and drive control method provided by the present invention have the following beneficial effects compared with the prior art: each wheel is driven by an electric drive mechanism and is equipped with a speed sensor. The main controller independently and cooperatively controls each wheel according to each speed, thereby realizing independent driving and independent speed regulation of the four motors, thereby providing more accurate driving force adjustment, ensuring wheel synchronization, and improving stability and work efficiency. BRIEF DESCRIPTION OF THE DRAWINGS In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 The present invention provides a schematic diagram of a four-motor pure electric grader drive system structure.

[0018] Figure 2 It is a schematic diagram of the structure of the front wheel steering components.

[0019] Figure 3 It is a schematic diagram of synchronous control flow.

[0020] Figure 4 It is a schematic diagram of the front wheel steering angle control process.

[0021] Figure 5 Schematic diagram of electronic differential control principle.

[0022] Figure 6 It is a schematic diagram of the electronic differential steering control process.

[0023] Figure 7 This is a simplified diagram of the steering principle of a grader.

[0024] Figure 2 Among them, 1- hydraulic oil tank; 2- steering pump; 3- steering motor; 4- proportional solenoid reversing valve; 5- steering hydraulic cylinder; 6- safety valve. DETAILED DESCRIPTION

[0025] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0027] Embodiment 1 Figure 1 FIG. 1 is a schematic diagram of a four-motor pure electric grader drive system provided by an embodiment of the present invention. Figure 1As shown, the system includes four electric drive mechanisms, each of which is connected to a wheel. A speed sensor for detecting the wheel speed is installed at each wheel. Each speed sensor is electrically connected to a main controller, and the main controller is electrically connected to each electric drive mechanism. The main controller controls the synchronous operation of the vehicles on both sides through the electric drive mechanism according to the speed of each wheel. Among them, the electric drive mechanism includes a drive motor, a reducer and a motor drive controller. The output end of the motor is connected to the wheel through the reducer. In this embodiment, the reducer and the drive motor are integrated into a whole and directly installed on the tire to provide power, so that the transmission chain is shorter and more efficient. The drive motor is electrically connected to the motor drive controller, and the motor drive controller is electrically connected to the main controller. The motor drive controller adjusts the drive motor current according to the instructions of the main controller to control the synchronous operation of the vehicles on both sides.

[0028] In this embodiment, each electric drive mechanism is powered by a power battery, which is a battery pack composed of multiple battery packs, and is equipped with an external charging interface to support a fast charging function. The power battery is connected to the drive motor through a motor drive controller to drive the motor of each drive mechanism.

[0029] The motor drive controller of this embodiment is connected to the main controller of the whole machine and can receive the adjustment signal from the operation control system. The motor drive controller of each mechanism can adjust the AC signal strength input to the motor, thereby controlling the speed and torque output by the motor to achieve synchronous control, steering control, etc.

[0030] like Figure 2 As shown, the driving system of this embodiment also includes a steering component connected to the front wheel. The steering component includes a steering motor 3, a steering pump 2, a proportional electromagnetic reversing valve 4 and a steering hydraulic cylinder 5. A steering hydraulic cylinder 5 position sensor is provided at the steering hydraulic pump; the steering hydraulic cylinder 5 position sensor and the proportional electromagnetic reversing valve 4 are electrically connected to the main controller respectively; the main controller controls the current of the proportional electromagnetic reversing valve 4 according to the detection signal of the steering hydraulic cylinder 5 position sensor to control the front wheel steering angle. The front wheel steering angle control process is described in detail below and will not be repeated here.

[0031] In addition, the main controller is also used to perform electronic differential steering control according to the actual steering angle when the vehicle is turning. The wheel electronic differential steering control process is described in detail below and will not be repeated here.

[0032] Embodiment 2 Based on the four-motor pure electric grader drive system provided in the first embodiment above, this embodiment provides a four-motor pure electric grader drive control method corresponding to the drive system, including a synchronization control process, a front wheel steering angle control process and an electronic differential steering control process.

[0033] Figure 3 It is a synchronous control flow diagram, such as Figure 5 As shown, the following steps are included.

[0034] S101, reading the rotation speeds of the wheels on the left and right sides, where the rotation speed of the wheel on each side is the average of the rotation speeds of the two wheels on the same side.

[0035] S102, detecting whether the synchronization control button is activated; if not activated, the synchronization control is not executed and the process is terminated; if activated, the next step is executed.

[0036] S103, calculating the difference in wheel speeds on the left and right sides.

[0037] S104, setting a small motor control current adjustment amount, recorded as a first small adjustment amount.

[0038] S105, determining whether the difference in wheel speeds on the left and right sides is less than a preset differential threshold; if so, ending the synchronous control; if not, executing the next step.

[0039] S106, determining whether the left side has a high rotation speed.

[0040] S107, if yes, then control the driving motor current of the left wheel to decrease by a first adjustment amount, the driving motor current of the right wheel to increase by a first adjustment amount, and re-read the left and right wheel speeds; otherwise, control the driving motor current of the left wheel to increase by a first adjustment amount, the driving motor current of the right wheel to decrease by a first adjustment amount, and re-read the left and right wheel speeds.

[0041] The speed sensor collects the speed of the vehicles on both sides. When the driver activates the synchronous control button, the two drive motors on the same side calculate the average speed to get the speed of that side, and divide the left and right sides into the faster side and the slower side according to the speed. Set a small amount (can be set in advance), and the main controller will reduce the speed of the faster side by a small amount and increase the speed of the slower side by a small amount after each scanning cycle. Repeat this process until the speed difference between the two sides is less than the preset allowable error value. Since the scanning cycle of the controller is usually very short, only 10ms, it can unify the speed of both sides in a short time, and the adjustment amount each time is very small, which can avoid over-adjustment and oscillation.

[0042] If the "small amount" value is too small, the adjustment speed will be very slow and will diverge due to the long adjustment time; if the value is too large, it may cause over-adjustment of the motors on both sides, causing the adjustment process to oscillate left and right. The small amount adjustment method selected in this design is bidirectional adjustment. If unidirectional adjustment is used, when the slow side unidirectionally follows the fast side adjustment method, if the power of the slow side has reached the maximum value, it will lose the ability to adjust; when the fast side unidirectionally follows the slow side adjustment method, if the motors on both sides cannot reach a higher speed at the same time, the whole machine will be limited by the speed of the slow side, and the speed loss will be large. The bidirectional adjustment method can avoid the shortcomings of the two unidirectional methods and is more conducive to the control and adjustment of straight-line driving.

[0043] Figure 4 It is a schematic diagram of the front wheel steering angle control process, such as Figure 4 As shown, the specific steps include the following steps.

[0044] A small current adjustment amount of the proportional electromagnetic reversing valve 4 is pre-configured, which is recorded as the second small adjustment amount; S201, reading the rotation speeds of the wheels on the left and right sides, where the rotation speed of the wheel on each side is the average of the rotation speeds of the two wheels on the same side.

[0045] S202, detecting whether the back key is in neutral.

[0046] S203, if yes, directly execute the next step, if not, check whether the wheel speeds on both sides are zero, if yes, execute the next step, otherwise end.

[0047] S204, reading the left handle voltage signal U1 and the steering hydraulic cylinder 5 position sensor voltage signal U2.

[0048] S205 , calculating the desired steering angle θ0 according to the voltage signal U1 , and calculating the actual steering angle θ according to the voltage signal U2 .

[0049] S206, determine whether θ<θ0.

[0050] S207, if so, the left electromagnet control current of the proportional electromagnetic reversing valve 4 is set to 0, and the right electromagnet control current is increased by a second small adjustment amount.

[0051] S208, if not, determine whether θ>θ0.

[0052] S209, if yes, make the right electromagnet control current of the proportional electromagnetic reversing valve 4 0, and increase the left electromagnet control current by a second small adjustment amount; if no, end.

[0053] The control of the steering angle of the grader is determined by two factors: the voltage signal U1 (0.5V~4.5V) of the control handle and the voltage signal U2 of the position sensor of the front wheel steering hydraulic cylinder 5. The voltage signal of the control handle is used as the input signal for steering control. 0.5V~2.4V indicates left turn, 2.4V~2.6V indicates middle position, and 2.6V~4.5V indicates right turn. The voltage signal U2 of the steering hydraulic cylinder 5 position is used as the feedback signal. The main controller calculates the actual steering angle θ of the current vehicle through the voltage value of U2, compares it with the expected steering angle θ0 corresponding to the input signal U1, and then sends an action current signal to the proportional electromagnet to adjust the current actual steering angle to the expected steering angle. , To control the current of the electromagnets on the left and right sides of the steering proportional electromagnet, In order to adjust the proportional electromagnet current in a small amount, the N gear represents neutral gear. When switched to neutral gear, the main controller stops sending signals to the motor controller, and the drive motor rotates freely driven by the wheels.

[0054] Figure 5 This is a schematic diagram of the electronic differential control principle. The electronic differential uses the speed difference between the inner and outer wheels to achieve different arc distances. When turning left, the left wheel speed can be reduced so that the left wheel speed is lower than the right wheel speed; when turning right, the right wheel speed can be reduced so that the right wheel speed is lower than the left wheel speed. The vehicle calculates the drive wheel speed difference based on the steering angle given by the control handle, and then calculates the speed difference of the drive wheel motors on both sides.

[0055] Figure 6 Schematic diagram of the electronic differential steering control process, which specifically includes the following steps.

[0056] S301, reading the actual steering angle θ and the current driving speed of the grader.

[0057] S302, calculating the rotation speeds of the left and right rear wheels using the following formula.

[0058] like Figure 7 As shown, θ is the vehicle turning angle θ1, θ2——front wheel steering angle; a, b——left and right wheelbase and front and rear wheelbase; v——speed of the grader when turning; r1, r2, r3, r4 – turning radius of the four wheels; v1, v2, v3, v4 – the rotation speeds of the four wheels.

[0059] From the figure, we can see that the relationship between θ, θ1 and θ2 is

[0060] The relationship of the turning radius is shown in formula (4.2).

[0061] When turning, the angular velocity of each wheel around point O must be the same, and the ratio of the wheel speeds is the ratio of the turning radius. The relationship between the wheel speeds of the driving wheels when turning is shown in formula (4.3).

[0062] Combining equations (4.2) and (4.3), we can get the speed of the driving wheels on the left and right sides: , The relationship is shown in formula (4.4).

[0063]

[0064]

[0065]

[0066] In the formula, is the rear left wheel speed, is the rear right wheel speed.

[0067] S303, calculating the rotation speed of the driving motors of the two rear wheels by the following formula.

[0068]

[0069]

[0070] In the formula, is the rear left wheel drive motor speed, is the transmission ratio from the rear left wheel drive motor to the rear left wheel, is the rear right wheel drive motor speed, is the transmission ratio from the rear right wheel drive motor to the rear right wheel, is the wheel circumference.

[0071] S304: Output instructions to the drive motors of the left and right rear wheels.

[0072] Step S303 calculates and obtains the rotation speeds of the driving motors of the two rear wheels, obtains the rotation speed increments of the two motors according to the current rotation speeds of the motors, and sends the motor rotation speed increment generation instruction to the driving motors.

[0073] The above disclosure is only a preferred embodiment of the present invention, but the present invention is not limited thereto. Any non-creative changes that can be thought of by a person skilled in the art, as well as several improvements and modifications made without departing from the principle of the present invention, should fall within the protection scope of the present invention.

Claims

1. A four-motor pure electric grader drive system, characterized in that: It includes four electric drive mechanisms, each of which is connected to a wheel. A speed sensor for detecting the wheel speed is installed at each wheel. Each speed sensor is electrically connected to a main controller, and the main controller is electrically connected to each electric drive mechanism. The main controller controls the synchronous operation of the vehicles on both sides through the electric drive mechanisms according to the speed of each wheel.

2. The four-motor pure electric grader drive system according to claim 1, characterized in that: The electric drive mechanism includes a drive motor, a reducer and a motor drive controller. The output end of the motor is connected to the wheel through the reducer, the drive motor is electrically connected to the motor drive controller, and the motor drive controller is electrically connected to the main controller. The motor drive controller adjusts the drive motor current according to the instructions of the main controller to control the synchronous operation of the vehicles on both sides.

3. The four-motor pure electric grader drive system according to claim 2, characterized in that: It also includes a power battery for supplying power to each electric drive mechanism, and the power battery is equipped with an external charging interface.

4. The four-motor pure electric grader drive system according to any one of claims 1 to 3, characterized in that: It also includes a steering component connected to the front wheels, which includes a steering motor, a steering pump, a proportional electromagnetic reversing valve and a steering hydraulic cylinder. A steering hydraulic cylinder position sensor is arranged at the steering hydraulic pump; the steering hydraulic cylinder position sensor and the proportional electromagnetic reversing valve are electrically connected to a main controller respectively; the main controller controls the proportional electromagnetic reversing valve current according to the detection signal of the steering hydraulic cylinder position sensor to control the steering angle of the front wheels.

5. The four-motor pure electric grader drive system according to claim 4, characterized in that: The main controller is also used to perform electronic differential steering control according to the actual steering angle when the vehicle is turning.

6. A four-motor pure electric grader drive control method, characterized in that: Including a synchronous control process, specifically including the following steps: Read the wheel speeds on both sides. The wheel speed on each side is the average of the two wheel speeds on the same side. Detect whether the synchronization control button is activated; If it is not started, the synchronization control will not be executed. If it is started, the next step will be executed; Calculate the difference in wheel speed between the left and right sides; Set a small motor control current adjustment amount, recorded as the first small adjustment amount; Determine whether the difference in wheel speeds on the left and right sides is less than a preset differential threshold; If yes, then end the synchronization control; if no, proceed to the next step; Determine whether the left side has a fast rotation speed; If so, the driving motor current of the left wheel is controlled to decrease by the first adjustment amount, the driving motor current of the right wheel is increased by the first adjustment amount, and the left and right wheel speeds are re-read; otherwise, the driving motor current of the left wheel is controlled to increase by the first adjustment amount, the driving motor current of the right wheel is decreased by the first adjustment amount, and the left and right wheel speeds are re-read.

7. The driving control method of a four-motor pure electric grader according to claim 6, characterized in that: It also includes a front wheel steering angle control process, which specifically includes the following steps: A small amount of current adjustment of the proportional electromagnetic reversing valve is pre-configured, which is recorded as the second small amount of adjustment; Read the wheel speeds on both sides. The wheel speed on each side is the average of the two wheel speeds on the same side. Detect whether the back button is in neutral; If yes, proceed to the next step directly. If no, check whether the wheel speeds on both sides are zero. If yes, proceed to the next step. Otherwise, end. Read the left handle voltage signal U1 and the steering hydraulic cylinder position sensor voltage signal U2; Calculate the desired steering angle θ0 according to the voltage signal U1, and calculate the actual steering angle θ according to the voltage signal U2; Determine whether θ<θ0; If yes, the control current of the left electromagnet of the proportional electromagnetic reversing valve is set to 0, and the control current of the right electromagnet is increased by a second small adjustment amount; If not, determine whether θ>θ0; If yes, the right electromagnet control current of the proportional electromagnetic reversing valve is set to 0, and the left electromagnet control current is increased by a second small adjustment amount; If not, then end.

8. The driving control method of a four-motor pure electric grader according to claim 7, characterized in that: It also includes an electronic differential steering control process, which specifically includes the following steps: Step 1, reading the actual steering angle θ and the current driving speed of the grader; Step 2, calculate the rear wheel speeds on the left and right sides by the following formula; In the formula, is the rear left wheel speed, is the rear right wheel speed, is the front and rear wheelbase, For the left and right wheelbase; Step 3, calculating the speed of the driving motors of the two rear wheels by the following formula; In the formula, is the rear left wheel drive motor speed, is the transmission ratio from the rear left wheel drive motor to the rear left wheel, is the speed of the rear right wheel drive motor, is the transmission ratio from the rear right wheel drive motor to the rear right wheel, is the wheel circumference; Step 4: Output instructions to the drive motors of the left and right wheels.

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