Dump Truck Braking Control for Rear Wheel Slip on Uneven Roads
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Solution Overview
Problem
Dump trucks experience uneven load distribution between front and rear wheels, leading to rear wheel slippage, especially on uneven roads, which deteriorates hydraulic brakes and requires frequent use of retard and service brakes, exacerbating slippage.
Innovation Solution
A dump truck with drive and driven wheels, controlled by an electric motor and hydraulic brakes, uses a controller to reduce regenerative torque when rear wheels slip, and activates driven wheel brakes to maintain overall braking torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If regenerative braking is used for normal braking, then energy recovery is improved, but drive wheel slippage occurs on uneven roads
Solution Approach 1:
The controller continuously monitors drive wheel peripheral velocity and calculates slip ratios. When slip ratio exceeds a threshold, the system automatically adjusts the regenerative torque command value to prevent slippage, creating a closed-loop feedback control system that balances energy recovery with wheel stability
Solution Approach 2:
The braking system dynamically switches between regenerative braking and friction braking modes based on real-time wheel slip conditions. The controller adjusts the inverter's regenerative torque command value dynamically, transitioning from pure regenerative braking to a hybrid mode that incorporates friction braking when slippage is detected
2Reliability
If service brake pedal is operated to stop drive wheel slippage, then braking effectiveness is improved, but brake shoe deterioration accelerates
Solution Approach 1:
The controller acts as an intermediary that manages the transition between regenerative braking and friction braking. It selectively applies friction braking only to the extent necessary to correct wheel slippage, rather than relying on full service brake application, thereby extending brake shoe life while maintaining braking effectiveness
Solution Approach 2:
The system changes the operational parameters of the braking system by adjusting the regenerative torque command value in response to slip conditions. This parameter adjustment reduces the need for friction braking intervention, thereby reducing wear on brake shoes while maintaining overall braking performance
3Reliability
If retad brake pedal operation amount is increased to prevent slippage, then drive wheel grip is improved, but rear wheel slippage is aggravated
Solution Approach 1:
The system applies different braking strategies to different wheel groups. When slip is detected, the controller selectively manages braking torque distribution, applying friction braking primarily to front driven wheels while maintaining regenerative braking on rear drive wheels, thereby addressing slippage locally without aggravating it
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Reduces drive wheel locking and ensures overall braking torque by adjusting regenerative torque and activating driven wheel brakes, minimizing brake wear and maintaining stability.
Implementation Method 1
a controller 13 for outputting a regenerative torque command value for generating a braking torque corresponding to an operation amount of the retard brake pedal 8 to the inverter 11 and for causing the inverter 11 to regeneratively control the electric motor 10
Implementation Method 2
a hydraulic valve 15 for generating a hydraulic pressure corresponding to an operation amount of the service brake pedal 9
Implementation Method 3
a solenoid proportional valve 18 for generating a hydraulic pressure
Implementation Method 4
a plurality of drive wheel peripheral velocity sensors 20 that sense respective peripheral velocities of the plurality of drive wheels
Implementation Method 5
a plurality of drive wheel brakes 16 combined with the plurality of respective drive wheels 6 and actuated according to the hydraulic pressure generated by the hydraulic valve 15
Data Source
AI summary
A dump truck reduces drive wheel braking torques to avoid locking drive wheels during slipping and generates braking torques for driven wheels to ensure an overall braking torque using a controller that outputs a regenerative torque command value, corresponding to a brake pedal operation amount, to an inverter that regeneratively controls electric motors. The controller reduces the regenerative torque command value and outputs a drive command value, corresponding to a regenerative torque command value reduction amount, to a solenoid proportional valve, when the controller determines that slip ratios of rear wheels equal or exceed a predetermined value. A hydraulic pressure generated by a hydraulic valve based on the brake pedal operation amount actuates rear wheel brakes. A hydraulic pressure selected by a higher-pressure selecting valve that selects the higher of the hydraulic pressure from the hydraulic valve and the hydraulic pressure from the solenoid proportional valve actuates front wheel brakes.