Deceleration-sensitive brake pressure control device

Claim 1

A deceleration-sensitive brake pressure control device for a vehicle, comprising: a valve body having a proportioning valve chamber for receiving brake fluid under pressure and supplying it to a brake; a pressure proportioning valve in said proportioning valve chamber and having a valve seat and a plunger means movable relative to said valve seat in response to the pressure of the brake fluid; said valve body having an inertia body chamber communicating with said proportioning valve chamber; said valve body having a sealing chamber having an opening thereinto from said inertia body chamber; an inertia body movable in said inertia body chamber in response to deceleration of the vehicle for closing the opening to said sealing chamber; a piston means communicating with said sealing chamber and movable in response to the pressure in said sealing chamber; a spring cage movably positioned between said plunger means and said piston means and normally spaced from said piston means a predetermined distance; stop means for limiting the movement of said spring cage away from said plunger means; a first spring having one end engaging said plunger means and the other end engaging said spring cage and normally in compression when said spring cage is engaged with said stop means for urging said plunger means in the valve opening direction; and a second spring having one end engaged with said piston means and having the other end blocked against movement relative to said valve body for resisting movement of said piston means toward said plunger means, whereby said piston means is moved to abut said spring cage and urge said spring cage and said plunger means to compress said first spring in the valve opening direction only after said piston means has moved toward said plunger means through the space between said piston means and said cage by compressing said second spring.