Lift Axle Control During Recuperation to Prevent Drive Wheel Slip
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Solution Overview
Problem
Existing motor vehicles face challenges in maintaining traction and optimizing energy recuperation during downhill travel, particularly due to wheel slip, which reduces the efficiency of electric energy generation and braking performance.
Innovation Solution
A motor vehicle equipped with a steering axle, drive axle, and lift axle, where the electric machine can operate as both a motor and generator, connected to an accumulator and control device, which detects wheel slip and adjusts the lift axle to redistribute load, ensuring better traction and energy generation during recuperation mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the motor vehicle uses a purely mechanical friction-based braking system, then braking performance is reliable, but energy recuperation efficiency is reduced
Solution Approach 1:
The patent combines the mechanical friction-based braking system with the electric machine operating in generator mode during recuperation. The control device coordinates both systems to work together, allowing energy recuperation through electrical generation while maintaining reliable braking capability through the mechanical system, thus resolving the contradiction between energy efficiency and braking reliability
Solution Approach 2:
The control device monitors the operational state of both the electric machine and mechanical braking system, dynamically adjusting their coordination based on real-time conditions. This feedback mechanism ensures optimal energy recuperation while maintaining sufficient braking performance across varying driving conditions
2Reliability
If the lift axle remains loaded during recuperation mode, then vehicle stability is maintained, but wheel slip occurs reducing traction
Solution Approach 1:
The patent makes the lift axle configuration dynamic by enabling it to be switched between loaded and relieved states depending on operating conditions. During recuperation mode, the control device can relieve the load on the lift axle to prevent wheel slip and improve traction on the drive axles, while maintaining vehicle stability through coordinated control of the electric machine and braking system
3Reliability
If the lift axle is relieved of load to improve traction, then wheel slip is prevented, but vehicle control complexity increases
Solution Approach 1:
The control device is designed with multi-functionality, integrating control of the electric machine, mechanical braking system, and lift axle into a single coordinated system. This universal control approach manages the complexity of coordinating multiple systems while achieving improved traction through lift axle relief during recuperation mode
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
This configuration enhances traction on the drive axle wheels, increases electrical energy generation, and maintains reliable braking and lane-keeping capabilities by variably adjusting the load on the lift axle, preventing wheel slip and improving the overall efficiency of the recuperation mode.
Implementation Method 1
the electric machine being further configured, when the motor vehicle is in a recuperation mode, to drive as a generator
Implementation Method 2
at least one actuator configured to lift and lower the at least one lift axle
Data Source
AI summary
A motor vehicle has a steering axle, a drive axle and a lift axle having an actuator for lifting and lowering the same. The wheels of the drive axle can be electrically driven, at least in a supporting manner, via an electric machine operable as an electric motor and as a generator, and the wheels can be driven in a generating manner in a recuperation operation. The electric machine is connected to an accumulator and to a control and/or regulation device to control the operation of the lift axle. The device is connected to sensors for wheel slip detection at the drive axle. The device is configured such that, during a recuperation operation, it can send a command to the actuator to lift the lift axle and thereby unload the wheels thereof, if there is wheel slip at least at one wheel of the drive axle.