Patent ID: 6079208
Filing Date: 2000-06-27
Classification: B60T

Abstract:
A master cylinder with hydraulic reaction for a pneumatic brake booster, comprising:a body pierced with a main bore;a cylindrical main piston pierced with a stepped secondary bore, said main piston being located in said main bore with a first end which is located outside of said body, said main piston receiving a boost force directed in a first direction, said main piston sliding in said main bore to delimit a working chamber, said working chamber being subjected to a hydraulic pressure developed by said main piston sliding in said main bore; anda reaction piston having a first end which is located outside of said body and a second end located in said secondary bore to define a reaction chamber, said reaction piston receiving an actuation force directed in said first direction such that said second end slides in said secondary bore to delimits a reaction chamber, said reaction chamber being in communication with said working chamber, said reaction piston moving with respect to said main piston as a function travel with a non-zero minimum amplitude for an actuation force gradient that exceeds a given threshold; said reaction piston being characterized by a push-rod element, an annular element surrounding said push rod element, and a tubular element extending from said push rod element in said first direction, a first shut-off seat formed on a front face of said tubular element; a second shut-off seat mounted at a first end of a seat support integral with said main piston and located in said reaction chamber; said second shut-off seat being located at a distance from said first shut-off seat that is approximately equal to said travel of said minimum amplitude; and at least a first spring which urges said reaction piston in a direction to move said first shut-off seat away from said second shut-off seat.