Brake Pedal Reaction Force Design Without Hydraulic Feedback
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Solution Overview
Problem
Conventional brake devices do not effectively enhance the operational feeling of the brake pedal, as the reaction force is generated through hydraulic pressure, which can lead to a less direct and less intuitive feedback for the driver.
Innovation Solution
A brake device configuration that includes a pedal operation detection section, a tank section, an actuator, a master cylinder with a piston rod, and a reaction force generating section with an elastic member, which directly transmits the reaction force to the brake pedal without relying on hydraulic pressure, allowing for improved operational feeling by eliminating the presence of brake fluid between the pedal and the reaction force generating section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If hydraulic pressure is used to generate reaction force on the brake pedal, then the braking function is achieved, but the operational feeling of the brake pedal becomes less direct and less intuitive
Solution Approach 1:
The system separates the reaction force generation function from the hydraulic braking function. The elastic member (spring) is dedicated to generating reaction force on the brake pedal, while the hydraulic system handles the actual braking. This segmentation allows each component to optimize its specific function, improving pedal feel without compromising braking performance.
Solution Approach 2:
The elastic member acts as an intermediary between the brake pedal and the hydraulic system. It provides direct mechanical feedback to the driver's foot while allowing the hydraulic system to handle the force multiplication and braking application. This intermediary component translates hydraulic pressure into intuitive mechanical feedback without requiring the driver to directly sense hydraulic pressure changes.
2Reliability
If brake fluid is present between the brake pedal and reaction force generating section, then hydraulic braking is enabled, but air may enter the system and affect reaction force generation
Solution Approach 1:
The reaction force generating section is extracted from the hydraulic system and positioned upstream, before the brake fluid flow path. The elastic member generates reaction force directly on the brake pedal without being in contact with brake fluid. This extraction eliminates the risk of air bubbles interfering with reaction force generation, as the elastic member operates in a separate mechanical domain rather than the hydraulic domain where air contamination is possible.
3Ease of operation
If the reaction force generating section is connected directly to the brake pedal, then operational feeling is improved, but the system becomes more complex
Solution Approach 1:
The reaction force generating section is merged with the master cylinder assembly, forming an integrated unit. The elastic member is positioned within the master cylinder housing and connected to the brake pedal through the existing mechanical linkage. This merging approach allows direct reaction force transmission without adding separate independent components, thereby improving pedal feel while minimizing the increase in overall system complexity.
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 the operational feeling of the brake pedal by providing a direct and intuitive reaction force, reducing the likelihood of air entering the system and maintaining the reaction force generation, even in malfunctioning states, thereby ensuring reliable braking performance.
Implementation Method 1
a reaction force generating section that is connected to the brake pedal and includes an elastic member that generates a reaction force on the brake pedal by elastically deforming according to the amount of operation of the brake pedal
Implementation Method 2
an actuator that pressurizes the brake fluid stored in the tank to a brake fluid pressure corresponding to the amount of operation of the brake pedal
Data Source
AI summary
A brake device includes a brake pedal, a pedal operation detection section, a tank section, an actuator, a master cylinder, a brake fluid path and a reaction force generating section. The master cylinder includes a cylinder section that forms a storage chamber for storing brake fluid and a piston rod that connects to the brake pedal and pushes out the brake fluid stored in the storage chamber and discharges the brake fluid to an outside of the cylinder section by moving a distance corresponding to an amount of operation of the brake pedal. The brake fluid flow path guides the brake fluid discharged from the storage chamber by being pushed out by the piston rod to the tank section. The reaction force generating section includes an elastic member that generates a reaction force on the brake pedal by elastically deforming according to the amount of operation of the brake pedal.