Patent ID: 7104059
Filing Date: 2006-09-12
Classification: B60T

Abstract:
1. A master cylinder comprising a cylinder body, a primary cup received in a groove defined in an inner periphery of said cylinder body by a front end wall, a rear end wall and a radially outer wall connecting said front and rear end walls together, a piston received in said cylinder body so as to be slidably guided by said primary cup, said cylinder body having a pressure chamber in which is stored a brake fluid adapted to be pressurized by said piston when said piston advances, said primary cup comprising a radially inner portion having a front end and kept in sliding contact with said piston, a radially outer portion having a front end and kept in sliding contact with said radially outer wall of said groove, and a base portion connecting said radially inner and outer portions together, said radially inner portion having at least one projection that protrudes forwardly from said front end of said radially inner portion to define a first fluid passage between said primary cup and said front end wall of said groove when said projection is in contact with said front end wall of said groove, whereby brake fluid from a reservoir can flow into said pressure chamber through a gap between a rear surface of said base portion of said primary cup and said rear end wall of said groove, through a gap formed between said radially outer portion of said primary cup and said radially outer wall of said groove, and through said first fluid passage.