Master cylinder having a proportioning and metering valve encapsulated in separate outlet ports

Claim 1

A proportioning valve apparatus for use in an outlet boss of a housing of a master cylinder comprising: a tubular housing located in said outlet boss and having a stepped bore with a first diameter section, a second diameter section and a third diameter section, said first diameter section being connected to a wheel brake and said third diameter receiving fluid from a pressurizing chamber in the master cylinder, said tubular housing having a radial bore for connecting the second diameter section to a passageway located in said housing of the master cylinder and connected to a reservoir, said tubular housing having first and second annular grooves located on the outer peripheral surface thereof on opposite sides of said radial bore; first and second seals located in said first and second grooves to prevent fluid communication along the stepped bore into said passageway, and said radial bore; a sleeve having a first peripheral surface which engages said second diameter section and a smaller second peripheral surface which extends into said third diameter section of the tubular housing, said sleeve having a first pressure surface adjacent the end of said first peripheral surface and a second pressure surface adjacent the end of said second peripheral surface, said first pressure surface having a larger effective area than said second pressure surface; seal means surrounding said second peripheral surface of said sleeve to prevent fluid communication from said third diameter section of said stepped bore to said passageway through said radial bore while allowing unrestricted fluid communication between said second diameter section and said passageway to establish a flow path to the reservoir for any fluid that may flow past said seal means in order to retain said any fluid within the master cylinder; a retainer connected to said smaller second peripheral surface of said sleeve; resilient means located in said third diameter section of said stepped bore for engaging said retainer and urging said sleeve toward said first diameter section of said stepped bore; and poppet mean located in said third diameter section for engaging said sleeve whenever a differential force generated by the fluid under pressure communicated to said third diameter of the bore from the pessurizing chamber acts on the first and second pressure surfaces of the sleeve in a manner to overcome the biasing force of the resilient means and move said sleeve toward said poppet means to interrupt the fluid communication between said third diameter section and said first diameter section, said sleeve responding to further increases in the pressure of the fluid in the pressurizing chamber by moving away from said poppet to allow the fluid pressure to the wheel brake to increase as a function of the ratio of the first pressure surface to the second pressure surface.