Supported line pressure power brake assembly

Claim 2

In a hydraulic power brake booster assembly having a housing with a pressure chamber therein and operator-actuated brake control means including a pedal rod means extending through said pressure chamber and a reaction piston, means including said reaction piston for producing sequential multistage reaction forces against said pedal in response to changes in pressurization in said pressure chamber comprising: said reaction piston being operably connected to said rod means to transmit reaction forces back to said pedal for providing the vehicle operator with a feeling of braking action; an elongated portion of said reaction piston extending into chamber means fluidly communicated with said pressure chamber and having surrounding wall means spaced from said elongated portion; said elongated portion having an end surface against which fluid pressure acts to produce a first level of reaction force opposing the operator''s force on said pedal; a reaction sleeve member reciprocally mounted on said elongated portion with seal means associated with one end and engaging the surrounding wall of the chamber means to present an annular area acted upon by said pressurized fluid to produce a supplemental reaction force and a resultant second level of reaction force upon said pedal; spring means engaging at one end of said reaction sleeve producing a force thereon opposing movement of the sleeve caused by pressurized fluid acting on said seal means; said spring means being supported at the other end in a noncommunicating manner with respect to said pedal so as not to impose a force thereon; means on said reduction piston adapted to be engaged by the second end of said reaction sleeve after a predetermined movement of the reaction sleeve against said spring whereby upon engagement the supplemental reaction force is added to the first level of reaction force to produce a second level of reaction force in response to increased pressurization of said pressure chamber.

Claim 3

In a hydraulic power brake booster assembly having a housing with a pressure chamber therein and operator-actuated brake control means including a pedal, rod means extending through said pressuRe chamber and a reaction piston, means including said reaction piston for producing sequential multistage reaction forces against said pedal in response to changes in pressurization in said pressure chamber comprising: said reaction piston being operably connectted to said rod means to transmit reaction forces back to said pedal for providing the vehicle operator with a feeling of braking action; an elongated portion of said reaction piston extending into chamber means fluidly communicated with said pressure chamber and having surrounding wall means spaced from said elongated portion; said elongated portion having an end surface against which fluid pressure acts to produce a first level of reaction force opposing the operator''s force on said pedal; a reaction sleeve member reciprocally mounted on said elongated portion and having a radially enlarged portion extending toward said surrounding wall means; an annular seal member adjacent said radially enlarged portion and engaging the surrounding wall means thereby presenting an annular area to be acted upon by pressurized fluid in said chamber means to produce a supplemental reaction force upon said pedal; spring means around said reaction sleeve having a first end engaging said radially enlarged portion to produce a force on said reaction sleeve opposing movement caused by pressurized fluid acting on said seal means; said spring being supported at its other end in a noncommunicating manner with respect to said pedal so as not to impose a force thereon; a shoulder portion of said reaction piston normally spaced a predetermined distance from the other end of said reaction sleeve when the pressure chamber and connected chamber means are unpressurized whereby increased fluid pressurization in said pressure chamber and connected chamber means produces a force on said sleeve causing it to initially compress said spring without applying a force on the pedal and subsequently when the sleeve engages the piston shoulder a supplemental reaction force is applied to the pedal in addition to the first level of reaction force to produce a second level of reaction force.

Claim 4

In a hydraulic power brake booster assembly having a housing with a pressure chamber therein and operator-actuated brake control means including a pedal, rod means extending through said pressuRe chamber and a reaction piston, means including said reaction piston for producing sequential multistage reaction forces against said pedal in response to changes in pressurization in said pressure chamber comprising: said reaction piston being operably connectted to said rod means to transmit reaction forces back to said pedal for providing the vehicle operator with a feeling of braking action; an elongated portion of said reaction piston extending into chamber means fluidly communicated with said pressure chamber and having surrounding wall means spaced from said elongated portion; said elongated portion having an end surface against which fluid pressure acts to produce a first level of reaction force opposing the operator''s force on said pedal; a reaction sleeve member reciprocally mounted on said elongated portion and having a radially enlarged portion extending toward said surrounding wall means; an annular seal member adjacent said radially enlarged portion and engaging the surrounding wall means thereby presenting an annular area to be acted upon by pressurized fluid in said chamber means to produce a supplemental reaction force upon said pedal; spring means around said reaction sleeve having a first end engaging said radially enlarged portion to produce a force on said reaction sleeve opposing movement caused by pressurized fluid acting on said seal means; said spring being supported at its other end in a noncommunicating manner with respect to said pedal so as not to impose a force thereon; a shoulder portion of said reaction piston normally spaced a predetermined distance from the other end of said reaction sleeve when the pressure chamber and connected chamber means are unpressurized whereby increased fluid pressurization in said pressure chamber and connected chamber means produces a force on said sleeve causing it to initially compress said spring without applying a force on the pedal and subsequently when the sleeve engages the piston shoulder a supplemental reaction force is applied to the pedal in addition to the first level of reaction force to produce a second level of reaction force.