A four-motor pure electric grader drive system and drive control method

Abstract

The application relates to the field of land levelers, and particularly discloses a four-motor pure electric land leveler driving system and a driving control method, which comprises four electric driving mechanisms, each of which is connected with a wheel, a rotating speed sensor for detecting the rotating speed of the wheel is installed at each wheel, each rotating speed sensor is electrically connected with a main controller, and the main controller is electrically connected with each electric driving mechanism; the main controller controls the synchronous operation of the two sides of the vehicle through the electric driving mechanism according to the rotating speed of each wheel. The application allows the rotating speed of each wheel to be independently controlled, so that more accurate driving force adjustment is provided, the wheels are guaranteed to be synchronous, and the stability and working efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of motor graders, and specifically to a four-motor pure electric motor grader drive system and drive control method. Background Technology

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

[0003] Electric graders primarily function through motor drive; however, most technologies employ a single motor to control four vehicles via a drive axle. This single-motor drive method can lead to uneven force distribution, affecting operational efficiency and machine stability. Especially on uneven or complex terrain, traditional graders struggle to maintain constant and synchronized speeds, impacting work performance and safety. Summary of the Invention

[0004] To address the aforementioned issues, this 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 drive 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 electric drive mechanism being connected to a wheel, and a speed sensor for detecting wheel speed being 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 one 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 current of the drive motor according to the instructions of the main controller to control the synchronous operation of the vehicles on both sides.

[0007] In an alternative implementation, a power battery is also included to supply power to each electric drive mechanism, and the power battery is equipped with an external charging interface.

[0008] In an optional embodiment, a steering component connected to the front wheels is also included. The steering component includes a steering motor, a steering pump, a proportional solenoid valve, and a steering hydraulic cylinder. A steering hydraulic cylinder position sensor is installed at the steering hydraulic pump. The steering hydraulic cylinder position sensor and the proportional solenoid valve are electrically connected to the main controller. The main controller controls the current of the proportional solenoid valve 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 implementation, the main controller is also configured to perform electronic differential steering control based on the actual steering angle when the vehicle is turning.

[0010] Secondly, the technical solution of the present invention provides a drive control method for a four-motor pure electric grader, including a synchronous control process, specifically including the following steps:

[0011] Read the rotational speeds of the left and right wheels. The rotational speed of each wheel is the average of the rotational speeds of the two wheels on the same side.

[0012] Check if the synchronization control button is activated;

[0013] If not started, synchronization control will not be performed; if started, proceed to the next step.

[0014] Calculate the difference in rotational speed between the left and right wheels;

[0015] Set a small adjustment amount for the motor control current, denoted as the first adjustment amount;

[0016] Determine whether the difference in rotational speed between the left and right wheels is less than a preset differential threshold.

[0017] If yes, then end synchronization control; otherwise, proceed to the next step.

[0018] Determine if the left side rotates faster;

[0019] If so, the drive motor current of the left wheel is reduced by a first adjustment amount, the drive motor current of the right wheel is increased by a first adjustment amount, and the rotation speeds of both wheels are read again; otherwise, the drive motor current of the left wheel is increased by a first adjustment amount, the drive motor current of the right wheel is reduced by a first adjustment amount, and the rotation speeds of both wheels are read again.

[0020] In an optional implementation, a front wheel steering angle control process is also included, specifically comprising the following steps:

[0021] A small amount of current adjustment for the proportional solenoid directional valve is pre-configured and denoted as the second adjustment amount.

[0022] Read the rotational speeds of the left and right wheels. The rotational speed of each wheel is the average of the rotational speeds of the two wheels on the same side.

[0023] Check if the back button is in neutral.

[0024] If yes, proceed directly to the next step; otherwise, check if the rotational speeds of both left and right wheels are zero. If yes, proceed to the next step; otherwise, end.

[0025] Read the voltage signal U1 of the left handle and the voltage signal U2 of the steering hydraulic cylinder position sensor;

[0026] The desired steering angle θ0 is calculated based on voltage signal U1, and the actual steering angle θ is calculated based on voltage signal U2.

[0027] Determine if θ < θ0;

[0028] If so, make the control current of the left electromagnet of the proportional solenoid valve 0, and increase the control current of the right electromagnet by the second adjustment amount.

[0029] If not, determine whether θ > θ0;

[0030] If so, make the control current of the right electromagnet of the proportional solenoid valve 0, and increase the control current of the left electromagnet by the second adjustment amount.

[0031] If not, then the process ends.

[0032] In an optional implementation, an electronic differential steering control process is also included, specifically comprising the following steps:

[0033] Step 1: Read the actual steering angle θ and the current speed of the grader;

[0034] Step 2: Calculate the rotational speed of the left and right rear wheels using the following formula;

[0035]

[0036] In the formula, The speed of the rear left wheel. The speed of the rear right wheel. This refers to the wheelbase between the front and rear wheels. The wheelbase is the distance between the left and right wheels.

[0037] Step 3: Calculate the speed increment of the drive motors for the two rear wheels using the following formula;

[0038]

[0039]

[0040] In the formula, This refers to the speed of the rear left wheel drive motor. This refers to the transmission ratio from the rear left wheel drive motor to the rear left wheel. This refers to the speed of the rear right wheel drive motor. This refers to the transmission ratio from the rear right wheel drive motor to the rear right wheel. The circumference of the wheel;

[0041] Step 4: Send commands to the drive motors of the left and right wheels.

[0042] The present invention provides a four-motor pure electric grader drive system and drive control method, which has the following advantages compared with the prior art: each wheel is driven by an electric drive mechanism and equipped with a speed sensor. The main controller independently and collaboratively controls each wheel according to each speed, realizing independent driving and independent speed adjustment of the four motors, thereby providing more precise drive force adjustment, ensuring wheel synchronization, and improving stability and work efficiency. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 This is a schematic diagram of a four-motor pure electric grader drive system provided in an embodiment of the present invention.

[0045] Figure 2 This is a schematic diagram of the front wheel steering component.

[0046] Figure 3 This is a schematic diagram of the synchronous control process.

[0047] Figure 4 This is a schematic diagram of the front wheel steering angle control process.

[0048] Figure 5 This is a schematic diagram of the electronic differential control principle.

[0049] Figure 6 This is a schematic diagram of the electronic differential steering control process.

[0050] Figure 7 This is a simplified diagram of the steering principle of a grader.

[0051] Figure 2 In the middle, 1-hydraulic oil tank; 2-steering pump; 3-steering motor; 4-proportional solenoid directional valve; 5-steering hydraulic cylinder; 6-safety valve. Detailed Implementation

[0052] To enable those skilled in the art to better understand the present invention, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0054] Example 1

[0055] Figure 1 This is a schematic diagram of a four-motor pure electric grader drive system provided in an embodiment of the present invention, as shown below. Figure 1 As shown, the system includes four electric drive mechanisms, each connected to a wheel. A speed sensor is installed at each wheel to detect its rotational speed. Each speed sensor is electrically connected to a main controller, which in turn is electrically connected to each electric drive mechanism. The main controller controls the synchronous operation of the vehicles on both sides based on the rotational speed of each wheel through the electric drive mechanisms. Each electric drive mechanism includes a drive motor, a reducer, and a motor drive controller. The motor's output is connected to the wheel via the reducer. In this embodiment, the reducer and drive motor are integrated into a single unit, directly mounted on the tire to provide power, resulting in a shorter transmission chain and higher efficiency. The drive motor is electrically connected to the motor drive controller, which is in turn electrically connected to the main controller. The motor drive controller adjusts the drive motor current according to the main controller's commands to control the synchronous operation of the vehicles on both sides.

[0056] In this embodiment, a power battery supplies power to each electric drive mechanism. The power battery is a battery pack composed of multiple battery packs, equipped with an external charging interface that supports fast charging. The power battery is connected to the drive motor via a motor drive controller, thereby driving the motors of each drive mechanism.

[0057] In this embodiment, the motor drive controller is connected to the main controller of the overall machinery and can receive adjustment signals from the operation control system. The motor drive controllers of each mechanism can adjust the strength of the AC signal input to the motor, thereby controlling the speed and torque output by the motor to achieve synchronization control, steering control, etc.

[0058] like Figure 2As shown, the drive system in this embodiment also includes a steering component connected to the front wheels. The steering component includes a steering motor 3, a steering pump 2, a proportional solenoid valve 4, and a steering hydraulic cylinder 5. A position sensor for the steering hydraulic cylinder 5 is installed at the steering hydraulic pump. The position sensor for the steering hydraulic cylinder 5 and the proportional solenoid valve 4 are electrically connected to the main controller. The main controller controls the current of the proportional solenoid valve 4 based on the detection signal from the position sensor for the steering hydraulic cylinder 5 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.

[0059] In addition, the main controller is also used to perform electronic differential steering control based on the actual steering angle when the vehicle is turning. The electronic differential steering control process of the wheels will be described in detail below, and will not be repeated here.

[0060] Example 2

[0061] Based on the four-motor pure electric grader drive system provided in Embodiment 1 above, this embodiment provides a four-motor pure electric grader drive control method corresponding to the drive system, including a synchronous control process, a front wheel steering angle control process, and an electronic differential steering control process.

[0062] Figure 3 This is a schematic diagram of the synchronous control flow, such as... Figure 5 As shown, it includes the following steps.

[0063] S101, read the rotational speed of the left and right wheels. The rotational speed of each wheel is the average of the rotational speeds of the two wheels on the same side.

[0064] S102, check if the synchronization control button is activated; if not activated, do not perform synchronization control and terminate the process; if activated, proceed to the next step.

[0065] S103, calculate the difference in rotational speed between the left and right wheels.

[0066] S104, set the motor control current adjustment to a small value, denoted as the first adjustment value.

[0067] S105, determine whether the difference in rotational speed between the left and right wheels is less than the preset differential threshold; if yes, end the synchronization control; otherwise, proceed to the next step.

[0068] S106, determine if the left side rotates faster.

[0069] S107, if yes, then control the drive motor current of the left wheel to decrease by the first adjustment amount, the drive motor current of the right wheel to increase by the first adjustment amount, and reread the rotation speed of the left and right wheels; otherwise, control the drive motor current of the left wheel to increase by the first adjustment amount, the drive motor current of the right wheel to decrease by the first adjustment amount, and reread the rotation speed of the left and right wheels.

[0070] The speed sensors collect the speeds of the vehicles on both sides. When the driver activates the synchronization control button, the two drive motors on the same side calculate the average speed to obtain the speed of that side. Based on the speed, the left and right sides are distinguished as the faster side and the slower side. A small amount (which can be preset) is set. Every time the main controller completes a scan cycle, the speed of the faster side decreases by a small amount, while the speed of the slower side increases by a small amount. This process is repeated until the speed difference between the two sides is less than the preset allowable error value. Since the controller's scan cycle is usually very short, only 10ms, the speed of both sides can be unified in a short time, and the adjustment amount each time is very small, which can avoid over-adjustment and oscillation.

[0071] If the "small" value is too small, the adjustment speed will be very slow, and it may diverge due to excessive adjustment time; if the value is too large, it may cause over-adjustment of both motors, resulting in left-right oscillation during the adjustment process. The small adjustment method chosen in this design is bidirectional adjustment. If unidirectional adjustment is used, when the slow side unidirectionally follows the fast side adjustment, if the power of the slow side has reached its maximum value, it will lose its adjustment capability; when the fast side unidirectionally follows the slow side adjustment, if both motors cannot reach a higher speed simultaneously, the whole machine will be limited by the speed of the slow side, resulting in a significant speed loss. The bidirectional adjustment method avoids the disadvantages of the two unidirectional methods and is more conducive to the control and adjustment of straight-line driving.

[0072] Figure 4 This is a schematic diagram of the front wheel steering angle control process, such as... Figure 4 As shown, the specific steps include:

[0073] The current adjustment of the proportional solenoid directional valve 4 is pre-configured as a small amount, denoted as the second adjustment amount;

[0074] S201, read the rotational speed of the left and right wheels. The rotational speed of each wheel is the average of the rotational speeds of the two wheels on the same side.

[0075] S202, check if the back button is in neutral.

[0076] S203, if yes, proceed directly to the next step; if no, check if the rotational speeds of both left and right wheels are zero. If yes, proceed to the next step; otherwise, end.

[0077] S204, read the voltage signal U1 of the left handle and the voltage signal U2 of the position sensor of the steering hydraulic cylinder 5.

[0078] S205 calculates the desired steering angle θ0 based on voltage signal U1 and the actual steering angle θ based on voltage signal U2.

[0079] S206, determine whether θ < θ0.

[0080] S207, if so, make the control current of the left electromagnet of the proportional solenoid directional valve 4 0, and increase the control current of the right electromagnet by the second adjustment amount.

[0081] S208, if not, determine whether θ>θ0.

[0082] S209, if yes, set the control current of the right electromagnet of the proportional solenoid directional valve 4 to 0, and increase the control current of the left electromagnet by the second adjustment amount; if no, then end.

[0083] The grader's steering angle is determined by two factors: the voltage signal U1 (0.5V~4.5V) from the control handle and the voltage signal U2 from the position sensor of the front wheel steering hydraulic cylinder 5. The control handle voltage signal serves as the input signal for steering control: 0.5V~2.4V indicates left turn, 2.4V~2.6V indicates center position, and 2.6V~4.5V indicates right turn. The voltage signal U2 from the steering hydraulic cylinder 5 position sensor serves as the feedback signal. The main controller calculates the actual steering angle θ of the vehicle based on the U2 voltage value, compares it with the desired steering angle θ0 corresponding to the input signal U1, and then sends an actuating current signal to the proportional electromagnet to adjust the current actual steering angle to the desired angle. , The current is controlled by the electromagnets on the left and right sides of the proportional steering electromagnet. The proportional electromagnet current is adjusted by a small amount. The N position indicates neutral. When switched to neutral, the main controller stops sending signals to the motor controller, and the drive motor rotates freely under the drive of the wheels.

[0084] Figure 5 This is a schematic diagram of the electronic differential control principle. Electronic differential control utilizes the speed difference between the inner and outer wheels to traverse different circular distances. When turning left, the speed of the left wheel is reduced, making it lower than the speed of the right wheel; when turning right, the speed of the right wheel is reduced, making it lower than the speed of the left wheel. The vehicle calculates the speed difference between the drive wheels based on the steering angle given by the control lever, and then calculates the speed difference between the motors of the two drive wheels.

[0085] Figure 6 This is a schematic diagram of the electronic differential steering control process, which includes the following steps.

[0086] S301, read the actual steering angle θ and the current speed of the grader.

[0087] S302, calculate the speed of the left and right rear wheels using the following formula.

[0088] like Figure 7 As shown, θ is the turning angle of the entire vehicle.

[0089] θ1, θ2 — Front wheel steering angles;

[0090] a, b — Left and right track width and front and rear wheelbase;

[0091] v — the speed at which the grader turns;

[0092] r1, r2, r3, r4 — the turning radius of the four wheels;

[0093] v1, v2, v3, v4 — the rotational speeds of the four wheels.

[0094] From the graph, we can see that the relationship between θ, θ1, and θ2 is as follows:

[0095]

[0096] The relationship of the turning radius is shown in equation (4.2).

[0097] When turning, the angular velocities of each wheel around point O must be the same, and the ratio of wheel velocities is the ratio of turning radii. Therefore, the relationship of wheel velocities of the drive wheels when turning is shown in equation (4.3).

[0098] By combining equations (4.2) and (4.3), the speeds of the left and right drive wheels can be obtained. , The relationship is shown in equation (4.4).

[0099]

[0100]

[0101]

[0102] In the formula, The speed of the rear left wheel. This refers to the rotational speed of the rear right wheel.

[0103] S303, the drive motor speeds of the two rear wheels are calculated using the following formula.

[0104]

[0105]

[0106] In the formula, This refers to the speed of the rear left wheel drive motor. This refers to the transmission ratio from the rear left wheel drive motor to the rear left wheel. This refers to the speed of the rear right wheel drive motor. This refers to the transmission ratio from the rear right wheel drive motor to the rear right wheel. This refers to the circumference of the wheel.

[0107] S304 outputs commands to the drive motors of the left and right rear wheels.

[0108] Step S303 calculates the speed of the drive motors of the two rear wheels, obtains the speed increment of the two motors based on the current motor speed, and sends the motor speed increment generation command to the drive motor.

[0109] The above-disclosed embodiments are merely preferred embodiments of the present invention, but the present invention is not limited thereto. Any non-creative variations that can be conceived by those skilled in the art, as well as any improvements and modifications made without departing from the principles of the present invention, should fall within the protection scope of the present invention.

Claims

1. A four-motor pure electric motor grader drive control method, characterized by, The application relates to a four-motor pure electric motor grader driving system, which comprises the following: Four electric drive mechanisms, each of which is connected with a wheel, a rotating speed sensor for detecting the rotating speed of each wheel is arranged at each wheel, each rotating speed sensor is electrically connected with a main controller, and the main controller is electrically connected with each electric drive mechanism; the main controller controls the synchronous operation of the two sides of the vehicle through the electric drive mechanisms according to the rotating speeds of the wheels; The electric drive mechanism comprises a driving motor, a speed reducer and a motor drive controller, the output end of the motor is connected with the wheel through the speed reducer, the driving motor is electrically connected with the motor drive controller, the motor drive controller is electrically connected with the main controller, and the motor drive controller adjusts the driving motor current according to the instruction of the main controller to control the synchronous operation of the two sides of the vehicle; The application further comprises a power battery for supplying power to each electric drive mechanism, and the power battery is provided with an externally-attached charging interface; The application further comprises a steering component connected with the front wheels, the steering component comprises 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 with the main controller; the main controller controls the current of the proportional electromagnetic reversing valve according to the detection signal of the steering hydraulic cylinder position sensor to control the steering angle of the front wheels; The main controller is further used for executing electronic differential steering control according to the actual steering angle when the vehicle is steering; The method comprises a synchronous control process, which specifically comprises the following steps: Reading the rotating speeds of the left and right wheels, and the rotating speed of each side of the vehicle is the average value of the rotating speeds of the two wheels on the same side; Detecting whether the synchronous control button is started or not; If the synchronous control button is not started, the synchronous control is not executed, and if the synchronous control button is started, the next step is executed; Calculating the rotating speed difference value of the left and right wheels; Setting a motor control current adjustment small amount, which is recorded as a first adjustment small amount; Judging whether the rotating speed difference value of the left and right wheels is smaller than a preset differential speed threshold value; If yes, the synchronous control is ended, and if no, the next step is executed; Judging whether the rotating speed of the left side is faster; If yes, the driving motor current of the left wheel is reduced by the first adjustment small amount, the driving motor current of the right wheel is increased by the first adjustment small amount, and the rotating speeds of the left and right wheels are read again; otherwise, the driving motor current of the left wheel is increased by the first adjustment small amount, the driving motor current of the right wheel is reduced by the first adjustment small amount, and the rotating speeds of the left and right wheels are read again; The application further comprises a front wheel steering angle control process, which specifically comprises the following steps: Pre-configuring a proportional electromagnetic reversing valve current adjustment small amount, which is recorded as a second adjustment small amount; Reading the rotating speeds of the left and right wheels, and the rotating speed of each side of the vehicle is the average value of the rotating speeds of the two wheels on the same side; Detecting whether the back key is in the neutral position or not; If yes, the next step is directly executed, if no, whether the rotating speeds of the left and right wheels are both zero is detected, if yes, the next step is executed, and if no, the process is ended; Reading a left handle voltage signal U1 and a steering hydraulic cylinder position sensor voltage signal U2; Calculating an expected steering angle theta 0 according to the voltage signal U1, and calculating an actual steering angle theta according to the voltage signal U2; Judging whether theta is smaller than theta 0 or not; If yes, the left electromagnet control current of the proportional electromagnetic reversing valve is 0, and the right electromagnet control current is increased by the second adjustment small amount; If no, judge whether θ> θ0; If yes, make the right side electromagnet control current of the proportional electromagnetic commutation valve 0, and increase the left side electromagnet control current by a second adjustment amount; If no, end.

2. The four-motor pure electric motor grader drive control method according to claim 1, characterized by, Also include electronic differential steering control process, specifically including the following steps: Step 1, read the actual steering angle θ and the current speed of the motor grader; Step 2, calculate the left and right rear wheel speeds by the following formula; In the formula, is the rotational speed of the left rear wheel, is the rotational speed of the right rear wheel, is the wheelbase of the front and rear wheels, is the track of the left and right wheels; Step 3, calculate the drive motor speed of the two rear wheels by the following formula; In the formula, is the rotational speed of the rear left wheel drive motor, is the transmission ratio of the rear left wheel drive motor to the rear left wheel, is the rotational speed of the rear right wheel drive motor, is the transmission ratio of the rear right wheel drive motor to the rear right wheel, is the wheel circumference; Step 4, output the command to the drive motors of the left and right wheels.

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