Master Cylinder Piston Indentation Sealing Member Damage
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Solution Overview
Problem
Existing master cylinder designs often damage the sealing member due to contact with the entrance of communication holes, particularly due to the slanted surfaces of the indentation portions on the piston's outer surface.
Innovation Solution
The master cylinder features a piston with an indentation portion on its outer surface, where multiple first communication holes are radially disposed on a planar surface perpendicular to the piston's longitudinal direction, and a second communication hole is formed on the rear wall of the indentation portion, which is also slanted, reducing the angle of collision with the sealing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If communication holes are formed in the planar surface of the piston with slanted front and rear walls, then the piston can effectively communicate between pressure chamber and hydraulic supplying chamber, but the sealing member contacts the entrance of the passageway and gets damaged
Solution Approach 1:
The patent applies local quality by creating a localized recess structure on the piston surface where communication holes are formed. The recess provides a specific local geometry with a bottom surface and rear wall that differs from the surrounding planar surface, allowing the sealing member to contact the recess bottom rather than the sharp edges of communication holes, thus protecting the sealing member while maintaining effective fluid communication
Solution Approach 2:
The recess structure acts as an intermediary between the communication holes and the sealing member. By introducing this intermediate geometric feature, the sealing member is redirected to contact the recess bottom surface instead of directly contacting the communication hole entrances, thereby mediating the interaction and preventing damage to the sealing member
Data Source
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AI summary
A master cylinder includes: a cylinder housing; a piston which is movably disposed in the cylinder housing so as to form a pressure chamber and a hydraulic fluid supplying chamber; and a sealing member which is interposed between the cylinder housing and the piston. An indentation portion is provided on an outer circumferential surface of the piston, and wherein a rear wall of the indentation portion is formed as a slanted surface. A plurality of first communication holes are formed on a bottom surface of the indentation portion and a second communication hole is formed on the rear wall of the indentation portion. According to the present invention, since the second communication holes which act as drag prevention passageway are formed on the rear walls which are slanted surfaces, an angle with which the sealing members collide with the edges of the second communication holes is reduced, so the damage of the sealing members can be reduced.