Patent attributes
A master cylinder includes a piston received in a cylinder body and formed with piston ports. An annular groove is formed in the inner periphery of the piston in its area where the piston ports are formed. An arcuate plate is received in the annular groove. A sleeve is inserted into the arcuate groove to retain the arcuate plate in the annular groove. A gap as a fluid passage is defined between the arcuate plate and the inner surface of the annular groove. A pressure chamber defined in the cylinder body communicates with a communication passage communicating with a reservoir through the above gap, cutouts of holes formed in the arcuate plate and holes formed in the sleeve. When hydraulic fluid flows rapidly from the pressure chamber toward the reservoir, the arcuate plate is adapted to elastically and radially expand, thus closing some of the piston ports.
