Abstract: An electrically actuated hydraulic power cylinder for use in a vehicle braking system. The power cylinder includes an electric motor, a rotary-to-linear actuator for converting rotary motion of the electric motor to a linear motion, and a hydraulic cylinder. In a preferred embodiment, the rotary-to-linear actuator is a roller screw assembly. The roller screw assembly converts rotational motion generated by the motor into axial movement of a piston which is disposed within the hydraulic cylinder. The movement of the piston pressurizes a volume of fluid. The pressurized fluid flows through an outlet port connected to either a single wheel brake cylinder or a plurality of wheel brake cylinders, thereby actuating the associated wheel cylinder. In a specific embodiment of the invention, the roller screw assembly is incorporated into the internal structure of the motor for compactness and weight reduction.

Abstract: A pedal simulator for a vehicle braking system. The pedal simulator is coupled to a brake pedal, and includes an electrical actuator operatively coupled to the brake pedal to selectively exert a force on the brake pedal. A position sensor is provided for generating a position signal indicative of the position of the brake pedal. A force sensor is provided for generating a force signal indicative of the force exerted upon the brake pedal by a driver. An electronic control unit is provided which has programmed therein a desired relationship between the position signal and the force signal. The electronic control unit determines an actual relationship between the position signal and the force signal and compares the actual relationship thus determined with the desired relationship. The electronic control unit controls the electrical actuator to selectively exert a force on the brake pedal to conform the actual relationship to the desired relationship.

Abstract: An improved electro-hydraulic brake system having features for improving the pedal feel of the system, while further having design features which contribute to the economy of manufacture of certain components of the system. The system provides for an electrically powered normal source of pressurized hydraulic brake fluid, and a manually powered backup source of pressurized hydraulic brake fluid to the vehicle brakes in the event of failure of the normal source. During normal braking, fluid from the backup source is redirected from the vehicle brakes to a pedal simulator. The pedal simulator preferably includes arrangements of spring loaded pistons, expansion volumes, and damping orifices, together with valves selectively controlling the flow of fluid to and from the pedal simulator which provides for an improved pedal feel during vehicle braking.

Abstract: An improved structure for an electrical actuation mechanism adapted for use in a disc brake assembly includes an electrical actuation mechanism adapted to be secured to an inboard leg of the caliper of the disc brake assembly. The electrical actuation mechanism includes a housing, an electrical motor disposed in the housing, and a spindle disposed in the housing and operatively coupled to the motor by a conversion gear assembly which is effective to convert rotary motion generated by the motor into axial movement of the piston. The spindle includes a shaft and a piston which can be coupled to the shaft by a dampening structure. The shaft is operatively connected to the motor for axial motion thereof, and the piston is operatively connected to a friction pad for engaging a rotor attached to a wheel of a vehicle in which the disc brake assembly is installed. The dampening structure can be comprised of elastomeric material or a fluid filled chamber defined between the piston and the shaft.