Inertia-type hydraulic brake pressure control valve

Claim 1

An inertia-type hydraulic brake pressure control valve for use in a vehicle braking system, said control valve comprising: a housing having therein first and second pressure chambers, an inlet communicating with said first pressure chamber and connectable to a vehicle source of hydraulic pressure, and an outlet communicating with said second pressure chamber and connectable to a vehicle rear wheel brake cylinder; a fluid passage connecting said first and second pressure chambers; inertia valve means positioned within said fluid passage for closing communication therethrough when deceleration of the vehicle exceeds a predetermined value; a plunger slidably positioned within a bore in said housing, said plunger having a first end exposed to pressure in said first pressure chamber and a second end exposed to pressure in said second pressure chamber; a piston separate from said plunger and slidably positioned within said housing, said piston having a first end always exposed to said pressure in said first pressure chamber during brake operation and a second end exposed to a predetermined reference pressure; first spring means mounted within said housing for urging said piston against the force thereon of said pressure in said first pressure chamber, said piston being movable against said first spring means when said pressure in said first pressure chamber exceeds a predetermined value; second spring means acting on said second end of said plunger for moving said plunger from a normal unactuated position in a first direction away from said second pressure chamber when said piston is moved against said first spring means and when said pressures in said first and second pressure chambers are equal; and means for limiting movement of said plunger in a second direction opposite to said first direction.