A gear shifting strategy of non-coal underground mine lithium battery trackless mine transport vehicle electro-hydraulic combined braking auxiliary

Abstract

A shifting strategy for an electro-hydraulic combined braking system in a lithium-ion battery-powered trackless mining vehicle for non-coal underground mines is disclosed. The system uses a vehicle controller to acquire inclinometer signals in real time. When the vehicle is on a downhill slope and its speed is within the shifting range, if a shifting request is received from the transmission controller, immediate shifting is prohibited, and an electro-hydraulic braking force switching procedure is initiated. The vehicle controller increases the current of the electro-proportional valve at a first rate, gradually engaging hydraulic braking force, while simultaneously decreasing the electro-braking force at a second rate, achieving a smooth replacement of electro-braking force by hydraulic braking force. Once the electro-braking force has been completely replaced by hydraulic braking force, the transmission is allowed to perform the shifting operation. After the shift is completed, the electro-proportional valve is closed, and the electro-braking force is restored. This invention links electro-hydraulic combined braking with automatic shifting, solving the problem of sudden speed increases or shifting failures caused by electro-braking failure during heavy-load downhill shifting, significantly improving the smoothness of vehicle shifting and operational safety.

Description

Technical Field

[0001] This invention belongs to the field of automatic transmission control technology for mining vehicles, specifically relating to a shifting strategy for electro-hydraulic combined braking assistance of a lithium battery trackless mining vehicle in a non-coal underground mine. Background Technology

[0002] Currently, lithium-ion battery-powered trackless mining vehicles used in non-coal underground mines generally employ speed-based multi-gear automatic mechanical transmissions to improve driving comfort and transmission efficiency. The vehicle control strategy typically prioritizes electric braking, meaning that when the vehicle is under heavy load and needs to decelerate downhill, the electric braking force generated by the traction motor is prioritized for braking.

[0003] However, when the vehicle speed reaches the shift trigger point, the transmission needs to shift gears. During the shift, the transmission disconnects the power connection between the traction motor and the drive wheels, causing the electric brakes to momentarily fail. Due to the lack of effective braking force, the vehicle will experience a rapid increase in speed under the influence of gravity, resulting in a "rollback" phenomenon. This not only affects the smoothness of gear shifts but may even lead to shift failures, and in severe cases, it can cause the vehicle to lose control, posing a significant safety hazard to underground transportation operations. In existing technologies, the electro-hydraulic combined braking system and the automatic mechanical transmission are controlled independently, lacking linkage. The hydraulic braking system does not provide effective assistance during the shift gap when the electric brakes fail. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a shifting strategy for a non-coal underground mine lithium battery trackless mining vehicle with electro-hydraulic combined braking assistance. Through the coordinated control of electro-hydraulic braking, the problem of sudden speed increase or shifting failure caused by power interruption during shifting under heavy load downhill electric braking conditions is solved, thereby improving the smoothness of vehicle shifting and operational safety.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a shifting strategy for electro-hydraulic combined braking assistance of lithium battery trackless mining vehicles in non-coal underground mines, comprising the following steps: Step 1: The vehicle controller acquires the inclinometer signal in real time to determine whether the vehicle is in a downhill condition; If the vehicle is not in a downhill condition, the vehicle controller allows the transmission controller to perform automatic gear shifting according to preset rules; If the vehicle is on a downhill slope, proceed to step 2; Step 2: The vehicle controller determines whether the current vehicle speed is within the preset shift speed range; If the current vehicle speed is not within the shift speed range, the vehicle controller will prohibit shifting and end the current control process. If the current vehicle speed is within the shift speed range, the vehicle controller will temporarily not allow shifting and will proceed to step 3. Step 3: The vehicle controller monitors whether the transmission controller sends a shift request signal; If there is no shift request, the vehicle controller will prohibit shifting and end the current control process; If there is a gear shift request, proceed to step 4; Step 4: The vehicle controller prevents the transmission controller from immediately performing a gear shift and simultaneously initiates the electro-hydraulic braking force switching procedure: Based on the current required braking force, the vehicle controller obtains the target current value of the electro-proportional valve corresponding to the required hydraulic braking force by looking up a table; the vehicle controller gradually increases the drive current of the electro-proportional valve to the target current value at a first rate, while controlling the traction motor to gradually reduce the electric braking force to zero at a second rate, achieving a smooth replacement of the electric braking force by the hydraulic braking force; when the electric braking force is completely replaced by the hydraulic braking force, the vehicle controller allows the transmission controller to perform a gear shift. Step 5: After the gear shift is completed, the vehicle controller closes the electric proportional valve and simultaneously controls the traction motor to gradually restore electric braking force at the second speed.

[0006] As an improvement, in step 4, the first rate is 0.2 mA / ms and the second rate is 200 N / s.

[0007] As an improvement, in step 5, if the gear shift fails, steps 4 and 5 are repeated to try shifting again; if the number of repeated gear shift failures reaches a preset threshold, the vehicle controller prohibits all gear shifting operations under the current downhill condition, controls the vehicle to lock gear operation, closes the electric proportional valve, and restores electric braking force.

[0008] As an improvement, the preset threshold is 3 times.

[0009] As an improvement, the vehicle controller is electrically connected to the inclinometer, the gearbox controller, the traction motor controller, and the electro-proportional valve, respectively.

[0010] The beneficial effects of this invention compared to the prior art are: 1. This invention links the electro-hydraulic combined braking system with the automatic mechanical transmission control system, and uses hydraulic braking to seamlessly replace the failed electric braking during gear shifting intervals, avoiding the "rolling" acceleration phenomenon caused by the interruption of braking force, and significantly improving the smoothness of the vehicle's gear shifting. 2. This invention ensures stable braking force during downhill gear shifting under heavy load by precisely controlling the switching of electro-hydraulic braking force, effectively avoiding the risk of sudden acceleration of the vehicle and greatly improving the operational safety of the vehicle under complex underground working conditions. 3. This invention provides a retry and gear lock protection mechanism after a gear shift failure, further enhancing the robustness and reliability of the control strategy. Attached Figure Description

[0011] Figure 1 This is a route diagram for the present invention. Detailed Implementation

[0012] The present invention will now be further described with reference to the accompanying drawings.

[0013] like Figure 1 As shown, a shifting strategy for electro-hydraulic combined braking assistance in a lithium battery-powered trackless ore transport vehicle for non-coal underground mines is based on the core principle of using the vehicle control unit (VCU) to coordinate the inclinometer, transmission control unit (TCU), and electro-proportional valve in the electro-hydraulic braking system to achieve smooth switching of braking force types. This strategy specifically includes the following steps: Step 1: The vehicle controller acquires the inclinometer signal in real time to determine whether the vehicle is in a downhill condition; If the vehicle is not in a downhill condition, the vehicle controller allows the transmission controller to perform automatic gear shifting according to preset rules; If the vehicle is on a downhill slope, proceed to step 2; Step 2: The vehicle controller determines whether the current vehicle speed is within the preset shift speed range; If the current vehicle speed is not within the shift speed range, the vehicle controller will prohibit shifting and end the current control process. If the current vehicle speed is within the shift speed range, the vehicle controller will temporarily not allow shifting and will proceed to step 3. Step 3: The vehicle controller monitors whether the transmission controller sends a shift request signal; If there is no shift request, the vehicle controller will prohibit shifting and end the current control process; If there is a gear shift request, proceed to step 4; Step 4: The vehicle controller prevents the transmission controller from immediately performing a gear shift and simultaneously initiates the electro-hydraulic braking force switching procedure: The vehicle controller looks up a table based on the current required braking force to obtain a target current value. Then, the vehicle controller linearly increases the current of the electro-proportional valve at a rate of 0.2mA / ms, gradually engaging the hydraulic braking force. At the same time, it sends a command to the traction motor controller to linearly decrease the electric braking force at a rate of 200N / s. This process ensures that the total braking force remains constant, avoiding vehicle impact. When the electric braking force completely drops to zero and the hydraulic braking force fully assumes the braking task, the vehicle controller sends a "gear shift permitted" command to the transmission controller, and the transmission begins to perform the gear shift operation. Step 5: After the transmission controller reports a successful shift, the vehicle controller immediately and linearly restores the electric braking force at a rate of 200 N / s, while simultaneously and quickly closes the electric proportional valve to disengage the hydraulic braking force. The vehicle then resumes its downhill deceleration state, primarily using electric braking.

[0014] To ensure successful gear shifts and prevent the system from looping indefinitely in a faulty state, this strategy also includes a retry mechanism and a gear lock protection mechanism. If the transmission controller reports a gear shift failure in step 5, the vehicle controller will repeat steps 4 and 5 to attempt the shift again. If three consecutive gear shifts fail, the vehicle controller determines that the system is abnormal. At this time, the vehicle controller will prohibit all gear shifting operations during the downhill journey, lock the transmission in the current gear, and forcibly close the electric proportional valve to fully restore electric braking force, ensuring the vehicle has basic downhill braking force and allowing it to safely travel to the maintenance area in the current gear.

[0015] The above control strategy is achieved by the vehicle controller communicating and coordinating with the inclinometer, transmission controller, traction motor controller, and electro-proportional valve in the electro-hydraulic braking system in real time through the controller area network (CAN bus).

Claims

1. A shifting strategy for electro-hydraulic combined braking assistance of lithium battery-powered trackless ore transport vehicles in non-coal underground mines, characterized in that, Includes the following steps: Step 1: The vehicle controller acquires the inclinometer signal in real time to determine whether the vehicle is in a downhill condition; If the vehicle is not in a downhill condition, the vehicle controller allows the transmission controller to perform automatic gear shifting according to preset rules; If the vehicle is on a downhill slope, proceed to step 2; Step 2: The vehicle controller determines whether the current vehicle speed is within the preset shift speed range; If the current vehicle speed is not within the shift speed range, the vehicle controller will prohibit shifting and end the current control process. If the current vehicle speed is within the shift speed range, the vehicle controller will temporarily not allow shifting and will proceed to step 3. Step 3: The vehicle controller monitors whether the transmission controller sends a shift request signal; If there is no shift request, the vehicle controller will prohibit shifting and end the current control process; If there is a gear shift request, proceed to step 4; Step 4: The vehicle controller prevents the transmission controller from immediately performing a gear shift and simultaneously initiates the electro-hydraulic braking force switching procedure: Based on the current required braking force, the vehicle controller obtains the target current value of the electro-proportional valve corresponding to the required hydraulic braking force by looking up a table; the vehicle controller gradually increases the drive current of the electro-proportional valve to the target current value at a first rate, while controlling the traction motor to gradually reduce the electric braking force to zero at a second rate, achieving a smooth replacement of the electric braking force by the hydraulic braking force; when the electric braking force is completely replaced by the hydraulic braking force, the vehicle controller allows the transmission controller to perform a gear shift. Step 5: After the gear shift is completed, the vehicle controller closes the electric proportional valve and simultaneously controls the traction motor to gradually restore electric braking force at the second speed.

2. The shifting strategy of electro-hydraulic combined braking assistance according to claim 1, characterized in that, In step 4, the first rate is 0.2 mA / ms and the second rate is 200 N / s.

3. The shifting strategy of electro-hydraulic combined braking assistance according to claim 1, characterized in that, In step 5, if the gear shift fails, steps 4 and 5 are repeated to try shifting again; if the number of repeated gear shift failures reaches a preset threshold, the vehicle controller prohibits all gear shifting operations under this downhill condition, controls the vehicle to lock gear operation, closes the electric proportional valve, and restores electric braking force.

4. The shifting strategy of electro-hydraulic combined braking assistance according to claim 3, characterized in that, The preset threshold is 3 times.

5. The shifting strategy of the electro-hydraulic combined braking assistance according to any one of claims 1 to 4, characterized in that, The vehicle controller is electrically connected to the inclinometer, gearbox controller, traction motor controller, and electro-proportional valve, respectively.

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