Booster Reaction Force Distribution for Consistent Brake Feel
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Solution Overview
Problem
The existing brake control apparatuses using fluid pressure control units for regenerative cooperative control experience variations in brake fluid pressure, leading to inconsistent brake pedal operation feelings due to changes in reaction force during regenerative braking.
Innovation Solution
A booster system is introduced, comprising an input member, an assisting member, an actuator, a reaction force distribution mechanism, and a reaction force application member, which delays the application of reaction force to the input member until a predetermined stroke is reached, ensuring consistent brake pedal operation by combining thrusts and distributing reaction forces effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If regenerative cooperative control is implemented using a fluid pressure control unit, then braking force distribution between friction braking and regenerative braking is improved, but brake fluid pressure varies causing inconsistent brake pedal operation feeling
Solution Approach 1:
A master cylinder is introduced as an intermediary component between the brake pedal and the fluid pressure control unit. The master cylinder absorbs pressure variations by storing excess brake fluid when pressure increases and releasing it when pressure decreases, thereby maintaining stable brake fluid pressure and consistent pedal operation feeling while enabling regenerative cooperative control
Solution Approach 2:
The system changes the operational parameters of the master cylinder by controlling the idle stroke position dynamically. By adjusting when the master cylinder starts generating pressure (idle stroke position) based on regenerative braking status, the system maintains stable pedal feel during regenerative cooperative control while preserving normal braking performance
2Productivity
If fluid pressure is increased or reduced by the fluid pressure control unit during regenerative cooperative control, then regenerative braking performance is improved, but the reaction force to the brake pedal operation varies
Solution Approach 1:
The master cylinder acts as a buffer between the fluid pressure control unit and the brake pedal, absorbing reaction force variations caused by fluid pressure adjustments during regenerative braking. This intermediary function maintains consistent reaction force to the pedal while enabling effective regenerative braking control
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
The booster system reduces variation in brake pedal reaction force during regenerative cooperative control, thereby enhancing the brake pedal operation feeling and maintaining a consistent braking experience.
Implementation Method 1
an actuator arranged to propel the assisting member in response to the movement of the input member
Implementation Method 2
a reaction force distribution mechanism arranged to combine thrust of the input member and thrust of the assisting member into a combined thrust and transmit the combined thrust to a piston of a master cylinder
Implementation Method 3
a piston of a master cylinder... keeps the master cylinder from generating a fluid pressure
Data Source
AI summary
An input rod is operated by a brake pedal to introduce the air into a variable-pressure chamber through a control valve to propel a power piston, thereby advancing a primary piston to generate a brake fluid pressure in a master cylinder. A part of the reaction force from the fluid pressure is transmitted to the input rod through a reaction member. The primary piston is provided with an idle stroke in which no fluid pressure is generated, and the reaction force to be transmitted to a plunger is limited by a reaction force adjusting spring. In the region of the idle stroke, a fluid pressure is supplied to a wheel cylinder through a fluid pressure control unit to perform regenerative cooperative control, and a reaction force from a reaction spring is applied to the input rod.