An off-highway wide-body dump truck automatic gear shifting control method

Abstract

The application provides an automatic gear shifting control method for off-highway wide-body dump trucks, which comprises the following steps: step S1, the gear shifting mode input received by the TCU is the automatic gear shifting mode D; step S2, the TCU searches the gear shifting up-down MAP diagram according to the throttle, brake pedal opening, left and right wheel speeds and motor speed information, and judges whether the gear shifting condition is met; step S3, when the TCU gear shifting permission signal is yes and the target gear position is different from the actual gear position, the TCU identifies the load and slope state of the vehicle; when the vehicle is identified as heavy load and uphill state, step S4 is executed; otherwise, step S5 is executed; step S4, the TCU enters the gear shifting up-down limiting state to limit the gear shifting up operation of the transmission; and step S5, the TCU enters the gear shifting control state. The application can better avoid the short-time frequent gear shifting up-down of the transmission under the automatic gear shifting mode in the heavy load uphill working condition.

Description

Technical Field

[0001] This invention belongs to the field of vehicle control technology, specifically relating to an automatic gear shifting control method for off-highway wide-body dump trucks. Background Technology

[0002] With the national push for the electrification and unmanned operation of off-highway wide-body dump trucks for mining, drive motors combined with AMT transmissions have become a common drive configuration for these trucks. As the load capacity of off-highway wide-body dump trucks gradually increases, some vehicles now weigh around 160 tons when fully loaded, while most AMT transmissions lack uninterrupted shifting capabilities. Vehicles with excessively heavy loads may experience noticeable shift jerking, power interruption during shifts, and gear skipping when climbing hills, which can severely damage the transmission.

[0003] The driver selects the mode via an electronic shifter in the cab. The AMT transmission has three modes: Manual Mode (M), Automatic Shift Mode (D), and Reverse Mode (R). The shifting strategy of existing AMT transmissions includes upshifting and downshifting in Manual Mode (M) and Automatic Mode (D). Existing pure electric off-highway wide-body dump trucks adopt the automatic shifting control logic of commercial vehicle AMTs. In Automatic Mode (D), the transmission controller (TCU) determines whether the vehicle meets the shifting conditions by recognizing information such as accelerator pedal opening, transmission output shaft speed, brake pedal depth, and motor speed. It also determines whether automatic shifting is needed by recognizing vehicle turning, braking, and coasting conditions.

[0004] For off-highway wide-body dump trucks used in mining, when the vehicle is heavily loaded and going uphill, the driver selects mode D. The automatic shift control process is as follows: The TCU (Transmission Control Unit) checks the transmission upshift and downshift MAP (Motor Transport Control Map) based on information such as throttle and brake pedal opening, left and right wheel speeds, and motor speed to determine whether the automatic shift conditions are met. During driving, as long as the motor speed rises to the motor speed corresponding to the transmission's upshift point, the control strategy of upshifting to the target gear by one level will be triggered. Similarly, when the motor speed decreases to the motor speed corresponding to the transmission's downshift point, pressing the accelerator during non-braking and non-turning conditions will also trigger the control strategy of downshifting to the target gear by one level.

[0005] Because power interruption occurs during gear shifting—specifically, the power supply is interrupted as the transmission moves from disengaged to neutral and then back to gear. If the transmission is intended to upshift, excessive vehicle load can cause a decrease in vehicle speed or rollback after upshifting, potentially triggering a downshift at the motor speed. Under specific conditions such as heavy-load uphill driving, the transmission may frequently upshift and downshift within a short period, affecting normal customer use and shortening the transmission's lifespan. Therefore, existing off-highway wide-body dump trucks require the use of manual mode (M) when heavily loaded uphill, and dynamic gear shifting is not permitted during this process.

[0006] Therefore, how to design an automatic shifting control method for off-highway wide-body dump trucks to better avoid frequent upshifting and downshifting in a short period of time when the transmission is under heavy load and going uphill in automatic shifting mode has become a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0007] The purpose of this invention is to provide an automatic gear shifting control method for off-highway wide-body dump trucks to solve the above-mentioned technical problems in the prior art.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] An automatic gear shifting control method for off-highway wide-body dump trucks includes the following steps:

[0010] Step S1: The shift mode input received by the TCU is automatic shift mode D;

[0011] Step S2: The TCU checks the transmission upshift / downshift MAP based on the throttle and brake pedal opening, left and right wheel speeds, and motor speed information to determine whether the shifting conditions are met.

[0012] Step S3: When the TCU shift permission signal is yes and the target gear is different from the actual gear, the TCU identifies the vehicle's load and gradient status. When the vehicle is identified as heavily loaded and uphill, step S4 is executed; otherwise, step S5 is executed.

[0013] Step S4: The TCU enters the upshift restriction state to restrict the upshift operation of the transmission;

[0014] Step S5: The TCU enters the shift control state.

[0015] Preferably, in step S3, the TCU determines whether the vehicle is under heavy load by using the vehicle load information provided by the load sensor installed on the vehicle.

[0016] Preferably, the method for determining whether a vehicle is under heavy load is as follows:

[0017] Let M be the unloaded mass of the off-highway wide-body dump truck;

[0018] Let m' be the upper limit of the measurement error of the load cell;

[0019] When the vehicle load value provided by the load sensor is greater than M+m', the vehicle is in a heavily loaded state.

[0020] Preferably, when the TCU does not receive information from the load sensor, it executes the same control method as when the vehicle is under heavy load.

[0021] Preferably, in step S3, the TCU determines whether the vehicle is in an uphill state by using the vehicle climbing angle information provided by the slope sensor installed on the vehicle.

[0022] Preferably, the method for determining whether a vehicle is in an uphill state is as follows:

[0023] Let α be the minimum gradient that needs to be restricted when the vehicle shifts gears;

[0024] When the angle provided by the slope sensor is positive and greater than α, the vehicle is in an uphill state.

[0025] Preferably, in step S4, the method by which the TCU performs the upshift restriction is as follows:

[0026] Let n be the motor speed corresponding to the upshift point of the transmission in the heavy-load climbing mode set by the TCU, where n < the maximum motor speed;

[0027] Let n' be the motor speed limit sent by the vehicle controller;

[0028] By setting n' < n, the motor speed is prevented from reaching the gearbox upshift point, thus limiting the gearbox upshifting.

[0029] Preferably, in step S5, the control method when the TCU enters the shift control state is as follows:

[0030] The TCU starts the torque mode and target torque, controls the vehicle controller to reduce the torque to the shift point, and the TCU enters the disengagement control;

[0031] The TCU controls the shifting mechanism to disengage from gear. After shifting from disengagement to neutral, the TCU enters speed regulation and gear selection control.

[0032] The TCU sends the target speed and speed mode to the vehicle controller, which then controls the drive motor to adjust the speed; the TCU also controls the gear selection mechanism to select the gear.

[0033] The TCU enters gear shift control, controls the gear shifting mechanism to engage gears, and simultaneously enters torque recovery control;

[0034] The TCU sends the torque mode and target torque, controls the motor controller to increase the torque to the required torque set in the vehicle controller, and then exits the shift control.

[0035] The beneficial effects of this invention are as follows:

[0036] The automatic gear shifting control method for off-highway wide-body dump trucks of the present invention can effectively avoid frequent upshifting and downshifting of the transmission in a short period of time when the transmission is under heavy load and going uphill in automatic gear shifting mode. It can also avoid the cumbersome operation of manually switching to manual mode M when the vehicle is under heavy load and going uphill, thus reducing human judgment and misoperation. Attached Figure Description

[0037] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly described below, and the specific embodiments of the present invention will be further described in detail with reference to the drawings, wherein...

[0038] Figure 1 A flowchart of an automatic gear shifting control method for off-highway wide-body dump trucks provided in an embodiment of the present invention;

[0039] Figure 2 A flowchart of the upshift restriction method under heavy-load climbing conditions provided in an embodiment of the present invention. Detailed Implementation

[0040] Various exemplary embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention.

[0041] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the invention or its application or use.

[0042] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0043] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0044] like Figure 1 and Figure 2 As shown, this embodiment of the invention provides an automatic gear shifting control method for off-highway wide-body dump trucks, which includes the following steps:

[0045] Step S1: The shift mode input received by the TCU is automatic shift mode D;

[0046] Step S2: The TCU checks the transmission upshift / downshift MAP based on the throttle and brake pedal opening, left and right wheel speeds, and motor speed information to determine whether the shifting conditions are met.

[0047] Step S3: When the TCU shift permission signal is yes and the target gear is different from the actual gear, the TCU identifies the vehicle's load and gradient status. When the vehicle is identified as heavily loaded and uphill, step S4 is executed; otherwise, step S5 is executed.

[0048] Step S4: The TCU enters the upshift restriction state to restrict the upshift operation of the transmission;

[0049] Step S5: The TCU enters the shift control state.

[0050] The automatic gear shifting control method for off-highway wide-body dump trucks provided in this embodiment of the invention can effectively avoid frequent upshifting and downshifting of the transmission in a short period of time when the transmission is under heavy load and going uphill in automatic gear shifting mode. It can also avoid the cumbersome operation of manually switching to manual mode M when the vehicle is under heavy load and going uphill, thus reducing human judgment and misoperation.

[0051] Furthermore, in step S3, the TCU determines whether the vehicle is under heavy load by using the vehicle load information provided by the load sensor installed on the vehicle.

[0052] Specifically, the method for determining whether a vehicle is under heavy load is as follows:

[0053] Let M be the unloaded mass of the off-highway wide-body dump truck, in tons;

[0054] Let m' be the upper limit of the measurement error of the load cell, in tons;

[0055] When the vehicle load value provided by the load sensor is greater than M+m', it is determined that the vehicle is not in an unloaded state, that is, the vehicle is in a heavily loaded state.

[0056] Furthermore, when the TCU fails to receive information from the load sensor, it assumes that the load sensor has malfunctioned. In this case, to avoid misjudgment, the same control method as when the vehicle is under heavy load is executed.

[0057] Furthermore, in step S3, the TCU determines whether the vehicle is in an uphill state by using the vehicle climbing angle information provided by the slope sensor installed on the vehicle.

[0058] Specifically, the method for determining whether a vehicle is going uphill is as follows:

[0059] Let α be the minimum gradient required to restrict vehicle gear shifting, in degrees;

[0060] When the angle provided by the slope sensor is positive and greater than α, the vehicle is in an uphill state.

[0061] Furthermore, in step S4, the TCU performs the upshift restriction as follows:

[0062] Let n be the motor speed corresponding to the upshift point of the transmission in the heavy-load climbing mode set by the TCU. n < the maximum motor speed, in rpm. This speed should be less than and as close as possible to the maximum motor speed.

[0063] Let n' be the motor speed limit sent by the vehicle controller (VCU), in rpm;

[0064] By setting n' < n, the motor speed cannot reach the gearbox upshift point. In this state, the gearbox cannot shift gears, and the motor speed will not exceed the maximum motor speed, thus preventing the motor controller (MCU) from overspeeding and achieving the purpose of limiting the gearbox upshift.

[0065] In other embodiments, when the vehicle is heavily loaded and climbing a hill, the motor speed can be controlled to drop to the downshift point of the transmission, and then the target gear can be downshifted by 1.

[0066] Specifically, in step S5, the control method when the TCU enters the shift control state is as follows:

[0067] The TCU starts the torque mode and target torque, controls the vehicle controller to reduce the torque to the shift point such as near 0, and the TCU enters the disengagement control;

[0068] The TCU controls the shifting mechanism to disengage from gear. After shifting from disengagement to neutral, the TCU enters speed regulation and gear selection control.

[0069] The TCU sends the target speed and speed mode to the vehicle controller, which then controls the drive motor to adjust the speed; the TCU also controls the gear selection mechanism to select the gear.

[0070] The TCU enters gear shift control, controls the gear shifting mechanism to engage gears, and simultaneously enters torque recovery control;

[0071] The TCU sends the torque mode and target torque, controls the motor controller MCU to increase the torque to the required torque set in the vehicle controller, and then exits the shift control.

[0072] This invention addresses the problem of frequent upshifts and downshifts in short periods under specific conditions, such as heavy-load uphill driving, in the automatic shifting mode of off-highway wide-body dump trucks by optimizing the control method in automatic transmission mode. By adding load and slope sensors, it can better identify whether the vehicle is under heavy load uphill driving. This invention, through optimized shifting control methods and logic, limits upshifting operations of the transmission under heavy load uphill driving conditions, while also resolving the problem of motor overspeed caused by the transmission not upshifting during high-speed vehicle operation, leading to overspeed faults in the motor controller. This invention also eliminates the cumbersome manual switching to manual mode M when the vehicle is heavily loaded uphill, reducing human judgment and operational errors.

[0073] This invention adds a judgment on the vehicle's heavy load and climbing conditions before shifting gears. By judging the current operating conditions of the vehicle, it determines whether the transmission should perform automatic shifting or upshift restriction. By restricting the upshifting of the transmission, the problem of frequent upshifting and downshifting of the transmission in a short period of time can be solved.

[0074] This invention determines whether a vehicle is in a heavy-load climbing condition by setting heavy-load judgment conditions and slope limits for the vehicle, and combining the current data from the load sensor and slope sensor. The specific settings can be set according to the vehicle's tonnage and the actual usage scenario.

[0075] The upshift restriction method of the present invention sets the motor speed and motor speed limit corresponding to the upshift point of the gearbox in heavy-load climbing mode, restricts the motor speed so that it cannot reach the upshift point of the gearbox, ensures that the gearbox cannot upshift, and also solves the risk of motor overspeed.

[0076] This invention targets off-highway wide-body dump trucks with a drive motor and AMT (Automated Manual Transmission) system, but it is also applicable to pure electric and range-extended vehicles. The AMT transmission involved in this invention is specifically designed for off-highway wide-body dump trucks and generally has no more than four gears. Transmissions with more gears can also use this control method, depending on the vehicle's calibration specifications.

[0077] While specific embodiments of the invention have been described in detail by way of examples, those skilled in the art should understand that the examples are for illustrative purposes only and not intended to limit the scope of the invention. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of the invention. The scope of the invention is defined by the appended claims.

Claims

1. An automatic gear shifting control method for off-highway wide-body dump trucks, characterized in that, It includes the following steps: Step S1: The shift mode input received by the TCU is automatic shift mode D; Step S2: The TCU checks the transmission upshift / downshift MAP based on the throttle and brake pedal opening, left and right wheel speeds, and motor speed information to determine whether the shifting conditions are met. Step S3: When the TCU shift permission signal is yes and the target gear is different from the actual gear, the TCU identifies the vehicle's load and gradient status. When the vehicle is identified as heavily loaded and uphill, step S4 is executed; otherwise, step S5 is executed. Step S4: The TCU enters the upshift restriction state to restrict the upshift operation of the transmission; Step S5: The TCU enters the shift control state.

2. The automatic gear shifting control method for off-highway wide-body dump trucks according to claim 1, characterized in that, In step S3, the TCU determines whether the vehicle is under heavy load by using the vehicle load information provided by the load sensor installed on the vehicle.

3. The automatic gear shifting control method for off-highway wide-body dump trucks according to claim 2, characterized in that, The method for determining whether a vehicle is under heavy load is as follows: Let M be the unloaded mass of the off-highway wide-body dump truck; Let m' be the upper limit of the measurement error of the load cell; When the vehicle load value provided by the load sensor is greater than M+m', the vehicle is in a heavily loaded state.

4. The automatic gear shifting control method for off-highway wide-body dump trucks according to claim 2, characterized in that, When the TCU does not receive information from the load sensor, it executes the same control method as when the vehicle is under heavy load.

5. The automatic gear shifting control method for off-highway wide-body dump trucks according to claim 1, characterized in that, In step S3, the TCU determines whether the vehicle is in an uphill state by using the vehicle climbing angle information provided by the slope sensor installed on the vehicle.

6. The automatic gear shifting control method for off-highway wide-body dump trucks according to claim 5, characterized in that, The method to determine whether a vehicle is going uphill is as follows: Let α be the minimum gradient that needs to be restricted when the vehicle shifts gears; When the angle provided by the slope sensor is positive and greater than α, the vehicle is in an uphill state.

7. The automatic gear shifting control method for off-highway wide-body dump trucks according to claim 1, characterized in that, In step S4, the TCU performs the upshift restriction as follows: Let n be the motor speed corresponding to the upshift point of the transmission in the heavy-load climbing mode set by the TCU, where n < the maximum motor speed; Let n' be the motor speed limit sent by the vehicle controller; By setting n' < n, the motor speed is prevented from reaching the gearbox upshift point, thus limiting the gearbox upshifting.

8. The automatic gear shifting control method for off-highway wide-body dump trucks according to any one of claims 1 to 7, characterized in that, In step S5, the control method when the TCU enters the shift control state is as follows: The TCU starts the torque mode and target torque, controls the vehicle controller to reduce the torque to the shift point, and the TCU enters the disengagement control; The TCU controls the shifting mechanism to disengage from gear. After shifting from disengagement to neutral, the TCU enters speed regulation and gear selection control. The TCU sends the target speed and speed mode to the vehicle controller, which then controls the drive motor to adjust the speed; the TCU also controls the gear selection mechanism to select the gear. The TCU enters gear shift control, controls the gear shifting mechanism to engage gears, and simultaneously enters torque recovery control; The TCU sends the torque mode and target torque, controls the motor controller to increase the torque to the required torque set in the vehicle controller, and then exits the shift control.

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