Patent ID: 7475952
Filing Date: 2009-01-13
Classification: B60T

Abstract:
1. A hydraulic control system for a brake apparatus, the hydraulic control system comprising: a combination valve; an actuator connected to the combination valve such that output by the actuator in a first direction places the combination valve in a first configuration, and output by the actuator in a second direction opposite the first direction places the combination valve in a second configuration different from the first configuration; the combination valve including an actuator pin operatively connected to the actuator such that the actuator pin is retracted using the actuator to place the combination valve in the first configuration and is extended using the actuator to place the combination valve in the second configuration; a cam driven by the actuator and having an eccentric surface and a follower having an outer surface that engages the actuator pin, the outer surface of the follower configured to extend and retract the actuator pin as the follower is moved by the cam; a clutch assembly, wherein rotation of the cam is controlled, at least in part, by the clutch assembly and the clutch assembly is configured to couple the cam with the actuator such that the cam rotates within a range less than 360 degrees as an output shaft of the actuator rotates; a pedal-operated master cylinder; and a controller connected to the actuator; wherein, in the first configuration, the combination valve allows hydraulic fluid to flow along a first fluid path and, in the second configuration, the combination valve allows hydraulic fluid to flow along a second fluid path different from the first fluid path; wherein the first fluid path forms part of a pressure modulation circuit and the second fluid path forms part of a pressure build circuit; wherein the controller controls the actuator to place the combination valve in the second configuration to increase braking pressure to initiate a controlled braking operation independent of user actuation of the pedal-operated master cylinder.