Patent ID: 6038857
Filing Date: 2000-03-21
Classification: B60T

Abstract:
A control apparatus for a brake system, said control apparatus comprising: a housing with a stepped bore therein; divider means for separating said stepped bore into a first chamber and a second chamber, said first chamber being connected with a source of fluid under pressure through an inlet port, a hydraulically operated device through a gear port, a reservoir through a relief port and a brake booster through an outlet port, said second chamber being connected to said reservoir; spool means located in said first chamber and having a peripheral surface with first and second grooves separated by lands and a operational bore, said operational bore being connected to said second groove by at least one radial passage and to said outlet port; cap means secured to said housing for sealing said stepped bore; first return spring means for positioning said spool valve within said first chamber such that pressurized fluid is communicated to said hydraulically operated device by way of said inlet port, first groove and said gear port; and actuation means located in said second chamber for moving said spool valve to restrict communication between said first groove and said gear port and divert pressurized fluid to said outlet port by way of said operational bore to effect a brake application, said actuation means being characterized by an input piston positioned in said second chamber by second return spring means and a plunger located in said second chamber, said plunger being connected to said input piston by an actuation spring, said input piston responding to an input force after overcoming said second return spring means by moving to allow said actuation spring to provide said plunger with a corresponding input force to move said spool valve and divert pressurized fluid to said operational bore to effect a brake application, said input piston movement being modified as a function of restricted fluid flow from said second chamber to limit the application of said input force from said plunger to said spool valve.