Two-Position Three-Way Valve for Brake Fluid Pressure Control
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Solution Overview
Problem
In brake-by-wire systems, the sudden change in brake fluid pressure when the electric motor is turned off can cause discomfort to the driver due to altered pedal feel, as the slave pistons are forced backward, increasing the fluid pressure chamber volume and leading to communication between the master cylinder, slave cylinder, and wheel cylinders.
Innovation Solution
A brake fluid pressure control system incorporating a two-position three-way valve that switches between states to prevent brake fluid from flowing into the second brake fluid line when the motor is shut off, allowing controlled communication between the master cylinder, slave cylinder, and wheel cylinders, and utilizing solenoid valves to manage power consumption and fluid pressure detection for optimal pedal feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is turned off while slave pistons are displaced toward the return side, then the slave pistons are forced backward increasing fluid pressure chamber volume, but this causes brake fluid to flow into the second brake fluid line altering pedal feel and giving discomfort to the driver
Solution Approach 1:
A two-position three-way valve is introduced as an intermediary component between the master cylinder and wheel cylinder. This valve selectively controls fluid communication paths: in a first position it allows direct communication for backup braking, and in a second position it routes fluid through the motor cylinder device. The valve prevents unwanted fluid flow into the second brake fluid line that would otherwise occur when the motor cylinder device is deactivated, thereby maintaining consistent pedal feel while preserving the backup brake function.
2Ease of operation
If the two-position three-way valve is used to prevent brake fluid flow into the second brake fluid line, then pedal feel consistency is maintained, but the device complexity increases
Solution Approach 1:
The two-position three-way valve is designed to switch positions automatically based on the operational state of the motor cylinder device. When the motor cylinder device is deactivated, the valve self-switches to a position that prevents fluid flow into the second brake fluid line, eliminating the need for complex external control mechanisms and reducing overall system complexity while maintaining pedal feel consistency.
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 system effectively maintains consistent pedal feel by preventing uncomfortable pressure changes, reducing power consumption, and ensuring smooth operation by controlling fluid flow based on detected pressures and system conditions.
Implementation Method 1
a brake hydraulic pressure control device that controls for regulating a brake hydraulic pressure; a master cylinder that generates a master cylinder pressure as a brake hydraulic pressure; a motor cylinder device that is arranged between the master cylinder and a wheel cylinder and generates a brake hydraulic pressure in response to an operation amount of the brake activator
Implementation Method 2
the two-position three-way valve may be switched from the second state to the first state on the condition that the operation of the brake activator is released. With this operation, when the brake activator is not operated, the master cylinder communicates with the wheel cylinder. For example, when the two-position three-way valve is formed of a solenoid valve, the two-position three-way valve is in the second state when the solenoid is on, and is in the first state when the solenoid is off
Data Source
AI summary
A brake fluid pressure control system for a vehicle is provided with: a master cylinder activated by the operation of a brake pedal; a motor cylinder device that generates brake hydraulic pressure in response to an operation amount of the brake pedal; first brake fluid flow lines that allow the master cylinder to communicate with wheel cylinders; two-position three-way valves arranged at connection points between the first brake fluid lines and second brake fluid lines. The two-position three-way valves switch between a state in which the master cylinder communicates with the wheel cylinder and a state in which the motor cylinder device communicates with the wheel cylinder.