Regenerative Brake Force Staging for Stable Vehicle Posture
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Solution Overview
Problem
Conventional vehicle brake systems with regenerative brake devices cause significant changes in vehicle posture due to uneven distribution of braking forces between front and rear wheels, leading to undesirable nose-diving or squatting postures during braking.
Innovation Solution
A brake system that, after reaching an allowable regenerative braking force, increases the friction braking force on one side to a level less than the actual braking-force distribution line, and then gradually increases both front and rear friction braking forces to align with the actual braking-force distribution line, thereby stabilizing the vehicle posture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the friction braking force of rear wheels is increased rapidly to reach the actual braking-force distribution line after regenerative braking force reaches allowable limit, then the braking force distribution reaches the target line faster, but the vehicle posture changes significantly in the front-rear direction causing nose-diving or squatting
Solution Approach 1:
The patent applies partial action by increasing the friction braking force of rear wheels to only 80-90% of the target braking-force distribution line value in the first stage, rather than reaching the full target value. This partial increase prevents excessive posture change while still providing substantial braking force. In the second stage, both front and rear wheel braking forces are increased together to reach the actual braking-force distribution line, completing the braking force distribution gradually and smoothly.
2Manufacturing precision
If the friction braking force of front wheels is increased simultaneously with rear wheels to reach the actual braking-force distribution line, then the braking force distribution follows the target line accurately, but the vehicle posture changes significantly due to uneven force distribution
Solution Approach 1:
The patent segments the braking force distribution process into two distinct stages: (1) First stage where only rear wheel friction braking force is increased to a controlled level (80-90% of target) while front wheel braking force remains minimal, and (2) Second stage where both front and rear wheel braking forces are increased together to reach the actual braking-force distribution line. This segmentation allows precise control over the rate and pattern of braking force application, preventing sudden posture changes while achieving accurate final distribution.
Solution Approach 2:
The patent applies preliminary action by first increasing the rear wheel friction braking force to a predetermined level (80-90% of target) before initiating the simultaneous increase of both front and rear wheel braking forces. This preliminary adjustment prepares the braking system for smooth transition, preventing abrupt posture changes when the full braking-force distribution line is eventually reached.
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 reduces the change in vehicle posture in the front-rear direction and prevents excessive front wheel lock by gently bringing the braking forces closer to the actual distribution line, enhancing braking stability.
Implementation Method 1
a motor generator 22 configured to function as a drive source for the drive wheels 4 or 6 and as a regenerative brake device
Implementation Method 2
a front-wheel brake device 38 configured to apply a friction braking force to the front wheels 2 and a rear-wheel brake device 40 configured to apply a friction braking force to the rear wheels 4
Data Source
AI summary
A vehicle brake system including a regenerative cooperative control device configured to control a regenerative brake device that applies a regenerative braking force to one of front and rear wheels and/or a friction brake device that applies a friction braking force to the front and rear wheels. After the regenerative braking force reaches an allowable regenerative braking force, the friction braking force applied to the other of the front and rear wheels is increased by the friction brake device up to a first friction braking force less than a braking force on an actual braking-force distribution line determined by the regenerative braking force at a time when it reaches the allowable regenerative braking force, and the friction braking forces applied to the one and the other of the front and rear wheels are subsequently increased so as to bring the friction braking forces close to the actual braking-force distribution line.