Brake anti-locking modulator with reapplication control

Claim 1

Apparatus for braking a vehicle wheel comprising hydraulic fluid responsive braking means for braking a wheel, hydraulic fluid conduit means connected to said braking means, means operatively communicating with said conduit means for applying there through hydraulic fluid pressure for braking the wheel, first and second controllable one-way valve means in series flow relation in said conduit means and defining there between a controlled conduit portion, each of said valve means having a valve member for permitting relatively large volume rates of flow and a seal element cooperating with said valve member for accommodating relatively small volume rates of flow, valve actuator means operatively coupled to said valve means for normally conditioning said valve means for free flow of fluid therethrough and operable for controllably conditioning said valve means to close said valve means against flow of fluid therethrough toward said braking means, said valve means and said valve actuator means cooperating when there are high pressure differentials across said valve means for sequentially opening first said seal elements and then said valve members and thereby facilitating reduction in forces required for valve means actuation, expansible chamber means operatively communicating with said controlled conduit portion for intermittently expanding and contracting the volume thereof, and sensor means responsive to braking of the wheel and operatively connected to said valve actuator means and said expansible chamber means for operating said means to modulate hydraulic fluid pressure.