Vehicle Braking Device Separator Seal Mounting Inversion
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Solution Overview
Problem
Conventional vehicle braking devices have a large axial size due to the need for a long separator to accommodate the seal member's sliding contact with the backup piston, increasing the overall device size.
Innovation Solution
The seal member for the annular passage is mounted to the inner periphery of the separator to repulsively contact the outer periphery of the backup piston, allowing the separator's axial length to be shortened, and the backup piston has a stepped cylindrical shape with a small and large diameter portion to facilitate the annular passage formation, reducing the device's axial length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the seal member is mounted to the outer periphery of the backup piston to seal the front side of the annular passage, then effective sealing is achieved, but the axial length of the separator must be set relatively long to secure the sliding contact portion, thereby increasing the axial length of the casing and the overall device size
Solution Approach 1:
The patent inverts the conventional mounting location of the seal member. Instead of mounting it to the outer periphery of the backup piston (conventional approach), the seal member is mounted to the inner periphery of the separator. This inversion allows the seal member to remain stationary on the separator while still achieving effective sealing against the backup piston's outer periphery, thereby eliminating the need for a long separator and reducing the axial length of the casing.
2Length of moving object
If the separator axial length is reduced to decrease device size, then compactness is improved, but the seal member may not have sufficient sliding contact length to maintain effective sealing during backup piston operation
Solution Approach 1:
By inverting the seal member's mounting location from the backup piston to the separator, the seal member becomes stationary while the backup piston moves against it. This allows the seal member to maintain continuous sliding contact with the backup piston's outer periphery throughout the entire stroke, ensuring effective sealing even with a shortened separator axial length.
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 reduces the axial size of the vehicle braking device while maintaining effective sealing and fluid pressure regulation, enhancing the device's compactness and efficiency.
Implementation Method 1
annular seal members for sealing front and rear sides of the annular passage being mounted between the separator and the backup piston, and between the sleeve and the backup piston
Implementation Method 2
a backup piston that has a closed front end facing the booster fluid pressure working chamber and is slidably housed in the casing so as to directly press the master piston from behind corresponding to an operation of the brake operation member when the output fluid pressure from the fluid pressure generation source is reduced
Implementation Method 3
pressure regulating valve means for regulating output fluid pressure from a fluid pressure generation source to fluid pressure corresponding to a brake operation input from a brake operation member to cause the fluid pressure to act on the booster fluid pressure working chamber
Data Source
AI summary
There is provided a vehicle braking device in which a front outer periphery of a backup piston that can directly press a master piston from behind when output fluid pressure from a fluid pressure generation source is reduced is fluid-tightly and slidably fitted to a short cylindrical separator, a sleeve forming an annular channel between itself and an outer periphery of the backup piston is placed backward of the separator, and annular seal members for sealing front and rear sides of the annular passage are mounted between the separator and the backup piston, and between the sleeve and the backup piston. The seal member for sealing a front side of the annular passage is mounted to an inner periphery of the separator so as to come into repulsive contact with the outer periphery of the backup piston. The seal member for sealing a rear side of the annular passage is mounted to the outer periphery of the backup piston so as to come into repulsive contact with an inner periphery of the sleeve. Thus, it is possible to reduce an axial size of the vehicle braking device.