FLUID BRAKE BOOSTER

摘要

A hydraulic brake booster includes a pressure piston 18 within a housing 12 movable in response to pressurized fluid within a pressure chamber 17 to effect a brake application. The piston encloses an auxiliary accumulator or storage chamber 60 and forms a bore 76 communicating the storage chamber 60 with the pressure chamber. A valve member 74 is disposed within the bore 76 to control communication between the storage chamber 60 and the pressure chamber 17. An operator operated actuator 40 cooperates with a control valve spool 30 to normally communicate pressurized fluid from a pump to the pressure chamber but a finger 100 is actuated by the operator actuator to engage the valve member 74, thereby opening communication between the storage chamber and the pressure chamber on pump failure. The valve member (Figure 2) comprises a unitary assembly having a sleeve 78 sealingly engaging the wall of the piston bore 76, a seat member 84 biased into engagement with a shoulder 82 defined by a stepped bore on the sleeve, and a stem 90 extending through a bore on the seat member and engageable by the finger 100.