Master Cylinder Valve Unit for Brake Fluid Flow Control
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Solution Overview
Problem
The existing master cylinder for brake systems experiences 'lost travel' and unintended braking pressure due to inefficient control of brake liquid flow, leading to a delay in braking operation and potential pressure generation irrespective of the driver's intention.
Innovation Solution
Incorporation of a valve unit with a check valve and fluid resistance holes in the brake liquid port to control unidirectional flow and reduce fluid velocity, ensuring prompt pressure increase during braking and preventing abnormal expansion of brake liquid.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the brake liquid port simply functions as a passage for brake liquid between the master cylinder and the reservoir, then the structure is simple, but the braking operation is delayed due to lost travel and unintended braking pressure may be generated
Solution Approach 1:
A valve unit is introduced as an intermediary component in the brake liquid port. This valve unit includes a check valve and a fluid resistance hole, which together control the flow of brake liquid between the reservoir and the liquid pressure chamber. The check valve allows brake liquid to flow in one direction while preventing reverse flow, and the fluid resistance hole restricts flow rate to prevent unintended pressure generation, thereby improving braking responsiveness without requiring complete structural redesign
Solution Approach 2:
The brake liquid port structure is modified by changing the flow parameters through the introduction of the valve unit. The check valve changes the flow direction parameter, allowing bidirectional control (supply and return), while the fluid resistance hole changes the flow rate parameter, restricting it to prevent drag. These parameter changes enable the system to achieve prompt braking operation while maintaining a relatively simple structure
2Productivity
If the brake liquid in the liquid pressure chamber is substantially discharged to the reservoir, then the liquid pressure chamber is not sealed, but a braking operation cannot be performed in the piston movement section
Solution Approach 1:
The check valve acts as a mediator that controls the discharge of brake liquid from the liquid pressure chamber to the reservoir. It allows brake liquid to be discharged when the piston moves backward (reducing lost travel) while preventing discharge when the piston moves forward (maintaining pressure for braking). This selective mediation enables the system to reduce lost travel without compromising braking efficiency
Solution Approach 2:
The valve unit introduces dynamic control into the previously static brake liquid port. The check valve dynamically opens and closes based on piston movement direction, and the fluid resistance hole dynamically adjusts flow rate based on pressure differential. This dynamic behavior allows the system to adapt to different operational phases (braking vs. return) and eliminate the fixed lost travel distance
3Reliability
If a caliper pad is moved rearwards or peripheral temperature rises, then brake liquid may abnormally expand, but braking pressure is generated irrespective of the driver's intention
Solution Approach 1:
The fluid resistance hole serves as a flow restriction intermediary that prevents abnormal expansion of brake liquid from causing unintended braking pressure. By restricting the flow rate of brake liquid into the liquid pressure chamber, it dampens pressure spikes caused by thermal expansion or caliper pad movement, thereby maintaining reliable braking control
Solution Approach 2:
The fluid resistance hole provides beforehand cushioning by pre-restricting the flow of brake liquid into the pressure chamber. This restriction acts as a buffer that absorbs and dampens sudden pressure increases before they can translate into unintended braking force, protecting the system against thermal expansion and abnormal fluid behavior
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 reduces lost travel and enhances braking reaction speed by increasing initial brake liquid flow, while preventing unintended braking pressure generation, thereby improving braking feeling and control.
Implementation Method 1
a valve unit including a check valve for controlling unidirectional flows of the brake liquid introduced from the reservoir to the liquid chamber
Implementation Method 2
a fluid resistance hole opened in two directions that is smaller than the size of the brake liquid discharge opening
Data Source
AI summary
Disclosed is a master cylinder for a brake system. The master cylinder includes a cylinder body that has a bore therein; at least one piston provided in the bore to be moved forwards and rearwards; a liquid pressure chamber compressed by the piston; a brake liquid port that is connected to a reservoir and configured to supply brake liquid to the liquid pressure chamber; and a brake liquid discharge opening for discharging the brake liquid in the liquid pressure chamber to a wheel brake of a wheel. A valve unit that includes a check valve to control the unidirectional flow of the brake liquid that is introduced from the reservoir to the liquid chamber and a fluid resistance hole opened in two directions and is smaller than the size of the brake liquid discharge opening is provided in the brake liquid port.