Brake Failure Response Control for 4WD EV Torque Redistribution
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Solution Overview
Problem
Four-wheel-drive electric vehicles lack technology to ensure stability when the brake system fails, leading to unpredictable braking force loss and unstable vehicle behavior, particularly in two-wheel-drive mode.
Innovation Solution
A control device that detects brake system failures and switches the vehicle from two-wheel-drive to four-wheel-drive mode by engaging a disconnector to redistribute torque between main and auxiliary driving wheels, using a controller to manage motor torque and limit vehicle speed to maintain stability during acceleration, coasting, and braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the vehicle travels in two-wheel-drive mode to reduce drag loss, then energy efficiency is improved, but vehicle stability deteriorates when brake system failure occurs
Solution Approach 1:
The system dynamically switches between two-wheel-drive and four-wheel-drive modes based on brake system status. The disconnector enables the auxiliary driving wheel to be disconnected during normal two-wheel-drive operation to reduce drag loss, but can be engaged when brake failure is detected to switch to four-wheel-drive mode and improve vehicle stability
2Reliability
If the disconnector is engaged to switch to four-wheel-drive mode upon brake failure, then vehicle stability is improved, but device complexity increases
Solution Approach 1:
The disconnector serves multiple functions: it acts as a power switch to reduce drag loss during normal two-wheel-drive operation, and simultaneously serves as a safety mechanism to switch to four-wheel-drive mode when brake failure is detected. This multi-functionality reduces the need for separate dedicated components
3Reliability
If brake system failure is detected in two-wheel-drive mode, then vehicle safety is improved, but torque distribution capability deteriorates
Solution Approach 1:
The system dynamically adjusts torque distribution by switching the disconnector state. When brake failure is detected, the system transitions from two-wheel-drive mode (torque to main driving wheel only) to four-wheel-drive mode (torque to both main and auxiliary driving wheels), thereby adapting torque distribution to the failure condition and improving both safety and torque distribution capability
Data Source
AI summary
A control device may be configured for responding to failure for ensuring the stability of a vehicle by switching from a two-wheel-drive mode to a four-wheel-drive mode when detecting failure of the brake system in a two-wheel-drive mode.