Electric loader travel control method, control device and loader

Abstract

The present invention relates to an electric loader. To solve the problem of travel control for a four-wheel independent drive electric loader, the present invention constructs a travel control method, a control device, and a loader for the electric loader. The control method comprises the following steps: detecting the depth of the accelerator pedal, determining the total drive torque of the loader based on the accelerator pedal depth, and distributing the drive torque of each wheel according to the total drive torque; detecting the rotational speed of the front and rear four-wheel drive motors and inferring whether each wheel is slipping; the drive torque distribution value of two of the front or rear wheels where the slipping wheel is located is proportionally reduced based on the current drive torque distribution value of the corresponding wheel until the slipping wheel does not slip; and after maintaining the distribution value for a predetermined time, the drive torque distribution value of each wheel is restored to the value before the reduction; and controlling the drive motor of each wheel based on the drive torque distribution value of each wheel. When the drive wheel of the electric loader slips, the present invention adjusts the drive torque of the front and rear wheels while combining automatic control of the working device to reduce slippage and improve the drive efficiency of the electric wheel.

Description

Technical Field

[0001] The present invention relates to an electric loader, and more particularly to an electric loader travel control method, a control device and a loader. Background Art

[0002] Electric loaders, especially four-wheel independent drive loaders, do not require a gearbox or drive axle, resulting in a simple transmission system structure and high transmission efficiency. Without the technical limitations of gearboxes and drive axles, loaders can more easily develop into larger tonnage. However, due to the complexity of four-wheel independent drive technology itself and the complexity of loader operating conditions, traditional electric vehicle travel control methods are difficult to fully adapt to the needs of four-wheel independent drive travel control of loaders. How to better control the loader's travel and improve its driving performance is an ongoing problem. Summary of the Invention

[0003] The technical problem to be solved by the present invention is the control problem of a four-wheel independent drive electric loader when it slips while traveling, and provides an electric loader travel control method, a control device and a loader.

[0004] The technical solution of the present invention to achieve its purpose is as follows: constructing a travel control method for an electric loader, wherein each of the four wheels of the loader is equipped with a mutually independent drive motor, and the control method includes the following steps:

[0005] S1: Detect the accelerator pedal depth, determine the total driving torque of the loader based on the accelerator pedal depth, and distribute the driving torque of each wheel according to the total driving torque;

[0006] S2: Detecting the rotational speeds of the drive motors of the front and rear four wheels and inferring whether each wheel is slipping, gradually reducing the drive torque distribution value of the two front or rear wheels where the slipping wheel is located in proportion to the current drive torque distribution value of the corresponding wheel until the slipping wheel stops slipping. After maintaining this state for a predetermined time, the drive torque distribution value of each wheel is restored to the value before the reduction;

[0007] S3: Controlling the driving motors of each wheel according to the driving torque distribution value of each wheel.

[0008] In the electric loader travel control method of the present invention, the loader state is detected and the weight of the material in the bucket is calculated based on the boom cylinder pressure during the shoveling and transporting phase, and the shoveling adjustment value of the driving torque is determined based on the calculated result of the weight of the material in the bucket;

[0009] In step S1, the driving torque allocated to each wheel is the average value of the total driving torque allocated to each wheel. When it is detected that the loader is in the shoveling and transporting stage, the front wheel driving torque distribution value is adjusted to the sum of the current driving torque distribution value and the shoveling adjustment value, and the rear wheel driving torque distribution value is adjusted to the difference between the current driving torque distribution value and the shoveling adjustment value.

[0010] In the electric loader travel control method of the present invention, the steering angle of the loader is detected, and the steering adjustment value of the inner and outer wheel driving torque is determined according to the steering angle;

[0011] In step S1, when the loader is in a steering state, the driving torque distribution value of the inner steering wheel is adjusted to the difference between the current driving torque distribution value of the wheel and the steering adjustment value, and the driving torque distribution value of the outer steering wheel is adjusted to the sum of the current driving torque distribution value of the wheel and the steering adjustment value.

[0012] In the electric loader travel control method of the present invention, in step S2, when it is detected that only the front wheel or the rear wheel has wheel slip, the reduced driving torque distribution values ​​of the two front wheels or the rear wheels where the slipping wheel is located are added equally to the driving torque distribution values ​​of the other two wheels.

[0013] In the electric loader travel control method of the present invention, the rate at which the driving torque of the slipping wheel decreases is in direct proportion to the rate at which the rotational speed of the driving motor of the slipping wheel increases.

[0014] In the electric loader travel control method of the present invention, in step S2, when it is detected that only the front wheel or the rear wheel has wheel slip and the accelerator pedal depth is detected, the increase in the total driving torque generated by deepening the accelerator pedal is added to the driving torque distribution value of the two wheels without slipping wheels among the front wheels or the rear wheels. When it is detected that both the front wheels and the rear wheels have wheel slip, the total driving torque does not increase with the accelerator pedal depression depth; when it is detected that the front wheels or the rear wheels have wheel slip, the driving torque of the front wheels and the rear wheels decreases synchronously with the decrease in the accelerator pedal depression depth.

[0015] In the electric loader travel control method of the present invention, when the loader is in the shoveling stage and the rear wheel slip is detected, accompanied by the bucket retraction action, the bucket solenoid valve group is controlled to automatically increase the current corresponding to the bucket retraction action to a set value, and the bucket solenoid valve group is intermittently controlled to increase and decrease the current corresponding to the bucket retraction action, and the automatic control of the bucket solenoid valve group current is exited after the set time; when the loader is in the shoveling stage and the front wheel slip is detected, the boom solenoid valve group is controlled to automatically raise the boom to a set height and then exit the boom automatic lifting control.

[0016] In the electric loader travel control method of the present invention, in step S2, when the difference between the driving motor speed of the driving wheel and the average speed of all driving motors is greater than a set value, or the difference between the driving motor speed of the driving wheel and the set upper limit value of the driving motor speed corresponding to the current driving torque of the driving wheel is greater than a predetermined value, it is inferred that the driving wheel is slipping.

[0017] The technical solution for achieving the purpose of the present invention is as follows: constructing a control device, which includes a processor and a memory, wherein the memory stores a control program, and the control program is loaded and executed by the processor to implement the electric loader travel control method as described above.

[0018] The technical solution for achieving the purpose of the present invention is as follows: construct a loader having the above-mentioned control device.

[0019] Compared with the prior art, the present invention adjusts the front and rear wheel drive torques when the electric loader drive wheels slip, while combining automatic control of the working device to reduce slippage and improve the electric wheel drive efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a block diagram of the electric loader travel control system of the present invention.

[0021] Figure 2 It is a flow chart of the electric loader travel control method of the present invention.

[0022] Figure 3 It is a block diagram of the electric loader travel control device of the present invention.

[0023] Parts names and serial numbers in the figure:

[0024] Controller 1, bucket solenoid valve group 2, boom solenoid valve group 3, pressure sensor 4, working device position sensor 5, accelerator pedal sensor 6, drive motor controller 7, drive motor 8. DETAILED DESCRIPTION

[0025] The specific implementation scheme is described below with reference to the accompanying drawings.

[0026] like Figure 1 As shown, the travel control system of the electric loader of the present invention includes a controller 1, a pressure sensor 4, a working device position sensor 5, an accelerator pedal sensor 6, a travel system, a hydraulic system, etc.

[0027] The pressure sensor 4 is electrically connected to the controller 1 and is used to measure the pressure of the large and small chambers of the boom cylinder.

[0028] The working device position sensor 5 is electrically connected to the controller 1 and is used to detect the rotation angle and / or position of the bucket and boom;

[0029] The accelerator pedal sensor 6 is electrically connected to the controller 1 and is used to detect the accelerator pedal's depression depth.

[0030] The traveling system is electrically connected to the controller and is used to receive control instructions from the controller to control the vehicle to move forward or backward;

[0031] The hydraulic system is electrically connected to the controller and is used to control the movement of the working device.

[0032] The travel system includes a drive motor 8, a drive motor reducer, and a drive motor controller 7. The drive motor controller 7 receives instructions from the controller 1 to control the operation of the drive motor 8 and sends speed and torque information to the controller 1. The electric loader is a four-wheel travel device, with each wheel equipped with a drive motor 8 to drive the four wheels, achieving independent drive travel.

[0033] The hydraulic system includes: a bucket solenoid valve group 2 and a boom solenoid valve group 3. The controller 1 controls the bucket solenoid valve group 2 to realize the bucket retracting and unloading actions, and the controller 1 controls the boom solenoid valve group 3 to realize the lifting and lowering actions of the boom.

[0034] The drive motor 8 is controlled by a torque mode. The controller 1 sends a corresponding torque instruction to the drive motor controller 7 according to the accelerator pedal's stepping depth and the loader's state to control the drive motor 8 to work.

[0035] The steps of the electric loader walking control method of the present invention are as follows: Figure 2 As shown, the details are as follows:

[0036] S1: Detects the accelerator pedal depth, determines the loader's total driving torque, T0, based on the accelerator pedal depth, and distributes the driving torque to each wheel based on the total driving torque. The accelerator pedal depth corresponds to the total driving torque, and the loader's total driving torque can be determined based on the depth of the accelerator pedal.

[0037] S2: Detecting the rotational speeds of the drive motors of the front and rear four wheels and inferring whether each wheel is slipping, gradually reducing the drive torque distribution value of the two front or rear wheels where the slipping wheel is located in proportion to the current drive torque distribution value of the corresponding wheel until the slipping wheel stops slipping. After maintaining this state for a predetermined time, the drive torque distribution value of each wheel is restored to the value before the reduction;

[0038] S3: Controlling the driving motors of each wheel according to the driving torque distribution value of each wheel.

[0039] In one embodiment, in step S1, the loader status is detected to determine the loader's current state. There are three loader states: pre-shovel loading phase, shovel loading phase, and shovel loading and transport phase. The loader determines the loader's state by detecting the working device's posture, such as the boom lift angle or boom cylinder extension, bucket cylinder extension or rocker arm rotation angle, boom cylinder main chamber pressure, and travel gear position.

[0040] If the loader is in forward gear and the working device is in the shoveling posture, and then the bucket is retracted or the boom is raised, it is determined that the loader has entered the shoveling stage, and it is not determined until the bucket retraction angle is greater than the predetermined angle, then it is determined to have exited the shoveling stage. The shoveling posture means that the loader's bucket is flat on the ground, and the boom angle and rocker arm angle are in the corresponding range. When the loader exits the shoveling stage, and when the boom and bucket are not moving, if the boom cylinder large chamber pressure is greater than the set value, then it is determined that the loader is in the shoveling and transportation stage, and it is not determined until the unloading operation occurs and the boom cylinder large chamber pressure is less than the set value, then it is determined to have exited the shoveling and transportation stage. When the loader is not in the shoveling stage and is not in the shoveling and transportation stage, it is determined that the loader is in the pre-shoveling travel stage.

[0041] When the loader detects that it is in the loading and transport phase, the weight of the material in the bucket is estimated based on the boom cylinder pressure. This estimated weight determines the shoveling adjustment value T2 for the drive torque. When the bucket is loaded with material, the loader's center of gravity shifts forward. During the loading and transport phase, distributing a greater amount of drive torque to the front wheels relative to the rear wheels maximizes the loader's performance. In the present invention, the shoveling adjustment value T2 is determined based on the weight of the material in the bucket, and this value is used to adjust the drive torque distribution between the loader's front and rear wheels. The greater the weight of the material in the bucket, the greater the shoveling adjustment value.

[0042] In one embodiment, in step S1, the steering angle of the loader is detected, and a steering adjustment value T3 for the driving torque of the inner and outer wheels is determined based on the steering angle. When the loader is turning, the inner wheels experience less driving resistance than the outer wheels. To ensure more efficient steering, a greater driving torque is allocated to the outer wheels relative to the inner wheels. The greater the steering angle, the greater the steering adjustment value for adjusting the driving torque of the inner and outer wheels.

[0043] In step S1, the driving torque of the loader's four driving wheels is distributed based on the total driving torque T0 and the loader's state. Specifically, the average value of the total driving torque T0 distributed to each wheel is used as the base value T1 of the driving torque distribution value for each driving wheel. Based on the base value T1, the corresponding addition and subtraction are performed to obtain the driving torque distribution value TC for each wheel. The details are as follows:

[0044] When the loader is in the pre-loading and loading phases and has no steering, the drive torque distribution value for each front and rear wheel is the same, serving as the base value. That is, the drive torque distribution value TC for each wheel is equal to the base value T1 (equal to T0 / 4). If the loader has steering, the drive torque distribution value for the wheel on the outside of the front or rear wheel is the base value T1 plus the steering adjustment value T3 (i.e., the drive torque distribution value TC for the outside wheel = T1 + T3). The drive torque distribution value TC for the wheel on the inside of the front or rear wheel is the base value T1 minus the steering adjustment value T3 (i.e., the drive torque distribution value TC for the outside wheel = T1 - T3).

[0045] If it is detected that the loader is in the shoveling and transporting stage, without steering, the driving torque distribution value TC of the two front wheels is the same, both of which are obtained by adding the shoveling adjustment value T2 to the basic value T1 (the driving torque distribution value TC of the front wheels = T1 + T2), and the driving torque distribution value TC of the two rear wheels is the same, both of which are obtained by subtracting the shoveling adjustment value T2 from the basic value T1 (the driving torque distribution value TC of the rear wheels = T1 - T2).

[0046] If the loader is in the loading and transporting phase and in a steering state, for the front wheels, the driving torque distribution value TC for the outer-turning wheels is obtained by adding the shoveling adjustment value T2 to the base value T1 and then adding the steering adjustment value T3 (driving torque distribution value TC for the outer-turning front wheels = T1 + T2 + T3). The driving torque distribution value TC for the inner-turning wheels is obtained by adding the shoveling adjustment value T2 to the base value T1 and then subtracting the steering adjustment value T3 (driving torque distribution value TC for the inner-turning front wheels = T1 + T2 - T3). For the rear wheels, the driving torque distribution value TC for the outer-turning wheels is obtained by subtracting the shoveling adjustment value T2 from the base value T1 and then adding the steering adjustment value T3 (driving torque distribution value TC for the outer-turning rear wheels = T1 - T2 + T3). The driving torque distribution value TC for the inner-turning wheels is obtained by subtracting the shoveling adjustment value T2 from the base value T1 and then subtracting the steering adjustment value T3 (driving torque distribution value TC for the outer-turning rear wheels = T1 - T2 - T3).

[0047] After the driving torque distribution value TC of each wheel is determined in step S1, in step S2, the driving torque distribution value TC of each wheel is dynamically adjusted based on the driving torque distribution value according to whether the vehicle is slipping.

[0048] In step S2, the speed of the drive motors of the four front and rear wheels is detected, and whether each wheel is slipping is estimated. The first scenario for estimating drive wheel slippage is when the difference between the drive motor speed of a drive wheel and the average speed of all drive motors is greater than a set value. The second scenario for estimating drive wheel slippage is when the difference between the drive motor speed of a drive wheel and the set upper limit of the drive motor speed corresponding to the current drive torque of that drive wheel is greater than a predetermined value. Specifically, when the loader vehicle is not slipping, the drive motor speed should be within a predetermined range to output a certain drive torque. If the drive motor speed exceeds this range, it is estimated that the vehicle corresponding to that drive motor is slipping.

[0049] When a drive wheel is presumed to be slipping, the drive torque distribution value to the relevant drive wheel is adjusted according to the position of the slipping wheel, as follows:

[0050] When the slipping wheel is any one or both of the two rear wheels, the driving torque distribution value of the two driving wheels in the rear wheels is gradually reduced in proportion to the value determined in step S1 until the slipping wheel stops slipping. After maintaining the non-slip state for a predetermined time, the driving torque distribution value of the two driving wheels in the rear wheels is restored to the value before the reduction.

[0051] The rate at which the pulley drive torque decreases is directly proportional to the rate at which the speed of the pulley drive motor increases, that is, the faster the speed of the drive motor increases, the greater the rate at which the pulley drive torque decreases (the faster the drive torque decreases).

[0052] Similarly, when the slipping wheel is any one or both of the two front wheels, the driving torque distribution value of the two driving wheels among the front wheels is gradually reduced in proportion based on the value determined in step S1 until the slipping wheel stops slipping. After maintaining the non-slip state for a predetermined time, the driving torque distribution value of the two driving wheels among the front wheels is restored to the value before the reduction.

[0053] In one embodiment, if only one of the front wheels is detected to be slipping (the rear wheels are not slipping), or only one of the rear wheels is detected to be slipping (the front wheels are not slipping), then while reducing the driving torque distribution value of the two driving wheels among the front wheels or rear wheels where the slipping wheel is located, the driving torque distribution value of the other two driving wheels is increased, and the reduced value of the driving torque distribution value of the slipping wheel is added equally to the other two driving wheels without slipping, so that the total driving torque distribution value of the four driving wheels of the loader remains unchanged.

[0054] In one embodiment, in step S2, when wheel slip is detected in only one of the front or rear wheels and an increase in the accelerator pedal's depression depth is detected, the increase in total driving torque resulting from deepening the accelerator pedal is added to the driving torque distribution value for the front or rear wheels that are not slipping. When wheel slip is detected in both the front and rear wheels, the total driving torque does not increase with the accelerator pedal's depression depth.

[0055] If wheel slip is detected on one of the front wheels or the rear wheels, the driving torque distribution value of the front and rear wheels will be reduced synchronously with the decrease in the depth of the accelerator pedal.

[0056] After the driving torque distribution value of each wheel is adjusted in step S2, the driving motor of each wheel is controlled according to the adjusted driving torque distribution value of each wheel.

[0057] In the above-mentioned electric loader travel control method, when the loader is in the shoveling phase and rear wheel slippage is detected, accompanied by bucket retraction, the bucket solenoid valve assembly is controlled to automatically increase the current corresponding to bucket retraction to a set value. The current of the bucket solenoid valve assembly corresponding to bucket retraction is then intermittently increased and decreased for a set period of time before automatic control of the bucket solenoid valve assembly current is terminated. If front wheel slippage is detected, the boom solenoid valve assembly is controlled to automatically raise the boom to a set height, after which automatic boom lift control is terminated.

[0058] An embodiment of the present application further provides a control device, which includes a processor and a memory, wherein a control program is stored in the memory, and the control program is loaded and executed by the processor to implement the aforementioned electric loader travel control method.

[0059] An embodiment of the present application also provides a loader having the aforementioned control device.

Claims

1. A method for controlling the travel of an electric loader, characterized in that: Each of the four wheels of the loader is equipped with independent drive motors. The control method includes the following steps: S1: Detect the accelerator pedal depth, determine the total driving torque of the loader based on the accelerator pedal depth, and distribute the driving torque of each wheel according to the total driving torque; S2: Detecting the rotational speeds of the drive motors of the front and rear four wheels and inferring whether each wheel is slipping, gradually reducing the drive torque distribution value of the two front or rear wheels where the slipping wheel is located in proportion to the current drive torque distribution value of the corresponding wheel until the slipping wheel stops slipping. After maintaining this state for a predetermined time, the drive torque distribution value of each wheel is restored to the value before the reduction; When the loader is in the shoveling stage and detects rear wheel slippage accompanied by bucket retraction, the bucket solenoid valve group is controlled to automatically increase the current corresponding to the bucket retraction action to the set value, and the bucket solenoid valve group is intermittently increased and decreased. After the set time, the automatic control of the bucket solenoid valve group current is exited. When the loader is in the shoveling stage and detects front wheel slippage, the boom solenoid valve group is controlled to automatically raise the boom to the set height and then exit the boom automatic lifting control. S3: Controlling the driving motors of each wheel according to the driving torque distribution value of each wheel.

2. The electric loader travel control method according to claim 1, characterized in that: Detect the loader status and calculate the weight of the material in the bucket according to the boom cylinder pressure during the shoveling and transporting stage, and determine the shoveling adjustment value of the driving torque based on the calculated result of the material weight in the bucket; In step S1, the driving torque allocated to each wheel is the average value of the total driving torque allocated to each wheel. When it is detected that the loader is in the shoveling and transporting stage, the front wheel driving torque distribution value is adjusted to the sum of the current driving torque distribution value and the shoveling adjustment value, and the rear wheel driving torque distribution value is adjusted to the difference between the current driving torque distribution value and the shoveling adjustment value.

3. The electric loader travel control method according to claim 2, characterized in that: Detecting the steering angle of the loader and determining the steering adjustment value of the inner and outer wheel drive torque according to the steering angle; In step S1, when the loader is in a steering state, the driving torque distribution value of the inner steering wheel is adjusted to the difference between the current driving torque distribution value of the wheel and the steering adjustment value, and the driving torque distribution value of the outer steering wheel is adjusted to the sum of the current driving torque distribution value of the wheel and the steering adjustment value.

4. The electric loader travel control method according to any one of claims 1 to 3, characterized in that: In step S2, when it is detected that only one of the front wheels or the rear wheels has wheel slip, the reduced driving torque distribution value of the two front wheels or the rear wheels where the slipping wheel is located is added to the driving torque distribution value of the other two wheels by an equal amount.

5. The electric loader travel control method according to any one of claims 1 to 3, characterized in that: In step S2, the rate at which the driving torque of the slipping wheel decreases is directly proportional to the rate at which the rotational speed of the driving motor of the slipping wheel increases.

6. The electric loader travel control method according to any one of claims 1 to 3, characterized in that: In step S2, when it is detected that only one of the front wheels or the rear wheels has wheel slip and the accelerator pedal depth is detected, the increase in the total driving torque generated by deepening the accelerator pedal is added to the driving torque distribution value of the two wheels without slipping, either the front wheel or the rear wheel. When it is detected that both the front and rear wheels have wheel slip, the total driving torque does not increase with the increase in the accelerator pedal's depression depth; when it is detected that one of the front wheels or the rear wheels has wheel slip, the driving torque of the front and rear wheels decreases synchronously with the decrease in the accelerator pedal's depression depth.

7. The electric loader travel control method according to claim 1, characterized in that: In step S2, when the difference between the driving motor speed of the driving wheel and the average speed of all driving motors is greater than a set value, or the difference between the driving motor speed of the driving wheel and the set upper limit value of the driving motor speed corresponding to the current driving torque of the driving wheel is greater than a predetermined value, it is inferred that the driving wheel is slipping.

8. A control device comprising a processor and a memory, wherein a control program is stored in the memory, characterized in that: The control program is loaded and executed by the processor to implement the electric loader travel control method according to any one of claims 1 to 7.

9. A loader, characterized in that: A control device according to claim 8 is provided.

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