Brake Pressure Split Control Under External Fluid Leakage
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Solution Overview
Problem
Existing braking control devices for vehicles face challenges in suppressing vehicle deflection and ensuring appropriate deceleration when external leakage of brake fluid occurs.
Innovation Solution
A braking control device that includes a master cylinder, an electrically driven fluid unit, and a controller that determines if external leakage has occurred, pressurizing the front wheel cylinder with the master cylinder and the rear wheel cylinder with the fluid unit to maintain stability and deceleration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the S-system wheel cylinders are pressurized by a fluid pressure source (pump) different from the master cylinder, then the braking force response is improved, but vehicle deflection occurs due to fluid pressure difference between P-system and S-system wheel cylinders
Solution Approach 1:
The braking system is divided into two independent subsystems: P-system (connected to master cylinder) and S-system (connected to pump). This segmentation allows each system to operate independently, enabling the patent to detect fluid pressure differences between systems and apply compensatory braking forces to prevent vehicle deflection while maintaining rapid response through the pump-driven S-system
Solution Approach 2:
The control unit continuously monitors the fluid pressure in both P-system and S-system wheel cylinders, comparing the pressures to detect imbalances. When a pressure difference is detected that would cause vehicle deflection, the control unit adjusts the braking force distribution between left and right wheels to compensate for the imbalance, thereby preventing vehicle deflection while maintaining the improved response characteristics
2Reliability
If the fluid surface level decreases in the reservoir tank, then the fluid pressure source can compensate by pressurizing, but vehicle deflection occurs due to unequal pressurization between P-system and S-system
Solution Approach 1:
The control unit continuously monitors fluid pressure in both systems and detects imbalances caused by fluid level changes. When the S-system experiences fluid level decrease, the control unit compensates by adjusting braking forces on individual wheels to maintain balance and prevent vehicle deflection
Solution Approach 2:
The system dynamically adjusts braking force parameters based on real-time fluid pressure conditions. When fluid level decreases affect S-system pressure, the control unit modifies the braking force distribution to maintain equilibrium between left and right sides, preventing vehicle deflection while ensuring reliable pressure maintenance
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 solution effectively prevents vehicle deflection and secures sufficient vehicle deceleration by managing brake fluid pressure distribution between the front and rear wheel cylinders during external leakage events.
Implementation Method 1
a master cylinder CM capable of pressure feeding brake fluid BF in conjunction with the movement of a brake operating member BP
Implementation Method 2
a secondary piston 32S having a shorter maximum stroke amount with respect to the primary piston 32P is moved to generate a brake fluid pressure in a first fluid path 11S connecting a secondary fluid pressure chamber 31S of the master cylinder 3 that generates a brake fluid pressure and S-system wheel cylinders 8b and 8c by a fluid pressure source (pump 7) different from the master cylinder 3
Implementation Method 3
the wheel cylinders 8a and 8d of the left front wheel and the right rear wheel, which are P systems, are pressurized by the master cylinder according to the brake pedal operation of the driver
Data Source
AI summary
A braking control device includes a “master cylinder CM capable of pressure feeding brake fluid BF in conjunction with the movement of a brake operating member BP of a vehicle”, an “electrically driven fluid unit HU”, “front wheel and rear wheel cylinders CWf, CWr that are provided on the front wheel and rear wheel WHf, WHr of the vehicle and are pressurized by either one of the master cylinder CM and the fluid unit HU”, and a “controller ECU that controls the fluid unit HU”. The controller ECU determines whether or not external leakage of a brake fluid BF has occurred in the braking control device, and when the external leakage has occurred, pressurizes the front wheel cylinder CWf by the master cylinder CM, and pressurizes the rear wheel cylinder CWr by the fluid unit HU.