Abstract: A piston pump comprises cylinder attached within a cavity of a pump housing. An outlet check valve seat is defined about an outlet of the cylinder. A piston is slidably received in a bore of the cylinder and has a first passageway formed therein. A cylinder head encloses the outlet of the cylinder and defines a second passageway therein. The first passageway has an inlet in fluid communication with the cavity of the pump housing, and an outlet in fluid communication with a pumping chamber defined in the pump housing. A first spring retains the piston to the cylinder. A first check valve member is a ball retained near a valve seat formed in the first passageway of the piston by a disk spring, and allows fluid to flow only from the inlet to the outlet of the piston.

Abstract: A piston pump comprises cylinder attached within a cavity of a pump housing. An outlet check valve seat is defined about an outlet of the cylinder. A piston is slidably received in a bore of the cylinder and has a first passageway formed therein. A cylinder head encloses the outlet of the cylinder and defines a second passageway therein. The first passageway has an inlet in fluid communication with the cavity of the pump housing, and an outlet in fluid communication with a pumping chamber defined in the pump housing. A first spring retains the piston to the cylinder. A first check valve member is a ball retained near a valve seat formed in the first passageway of the piston by a disk spring, and allows fluid to flow only from the inlet to the outlet of the piston.

Abstract: A pedal simulator utilizing springs to provide a brake pedal with a non-linear, progressively increasing response characteristic for pedal travel versus force exerted on the brake pedal similar to a conventional hydraulic braking system. In a preferred embodiment, the pedal simulator is integrated into the housing of an associated master cylinder. The non-linear, progressively increasing response characteristic is provided in one embodiment by a conical spring having a non-uniform helix angle. In second and third embodiments, the non-linear, progressively increasing response characteristic is provided by a plurality of cylindrical coil springs.

Abstract: A copy valve for an anti-lock brake system. The copy valve has a housing enclosing four chambers. A first and fourth chamber of the enclosed four chambers receives pressurized fluid directly from the first and second cylinders of a dual master brake cylinder. The third chamber receives the pressure of the controlled brake actuator while the second chamber is connectable to the uncontrolled brake actuator. In one embodiment, a single piston is enclosed in the housing and the first and second chambers are disposed at the opposite ends of the piston. The piston has an enlarged collar intermediate the two ends which is received in an annular recess provided in the housing. The third chamber is formed between a first face of the piston's enlarged collar and the annular recesses while the fourth chamber is formed between the opposite face of the piston's enlarged collar and the adjacent face of the housing. A throughbore is provided through the piston connecting the first and second chambers.

Abstract: An anti-lock braking system having an anti-lock braking control which periodically increases the speed of the engine during the anti-lock mode of operation. The anti-lock braking control detects the deceleration of the driven wheel speed when each periodic increase in engine speed is terminated, to detect the transition in the driven wheels from a low friction road surface to a high friction road surface. Upon the detection of the transition to a high friction road surface, the anti-lock brake control terminates the increased engine speed and increases the brake fluid pressure to the driven wheel actuators to maintain maximum anti-lock braking torque.

Abstract: An accumulator assembly for a vehicle anti-lock brake system receives and temporarily stores fluid during pressure reduction phases of the anti-lock operation, and maintains fluid stored therein substantially at or near zero pressure during anti-lock operation. The accumulator enables the fluid pressure to the controlled brakes to be reduced to substantially near zero pressure. The accumulator is further operative, after braking of the vehicle, to apply a predetermined pressure above zero pressure to the brake fluid stored therein to enable the fluid to be returned to the brake system. The accumulator is advantageously used in a pumpless anti-lock system which is operative to control the rear disc brakes of a light pick-up truck.

Abstract: A vehicle braking system such as an anti-lock brake system and/or a traction control utilizes a separate solenoid-actuated, two position, three-way valve in each controlled channel of the brake system for controlling the application of pressure to the respective wheel brake circuit. The valve includes a first port connected to the controlled wheel brake(s), a second port connected to an outlet of a hydraulic pump, and a third port connected to the inlet of the hydraulic pump. The valve is only moveable between a first position wherein the outlet of the pump is connected to the wheel brake to increase pressure to the wheel brake, and a second position wherein the wheel brake is connected to the inlet of the pump to decrease pressure to the wheel brake. An electronic control is provided for operating the valve to control the application of pressure to the selected wheel brakes.

Abstract: In accordance with the present invention, a normally open isolation valve is connected between a master cylinder and the selected wheel brakes, and a normally closed dump valve is connected between the selected wheel brakes and a fluid accumulator. A computer control module is connected to operate the isolation valve and the dump valve. In operation, when a slip condition of the controlled wheels is detected, the computer control module closes the isolation valve to hold fluid pressure to the controlled brakes at a relatively constant level. If the deceleration of the controlled wheels exceeds a predetermined amount, the computer control module will selectively open the dump valve to enable fluid to flow into the accumulator, thereby reducing the deceleration of the associated wheels.

Abstract: The present invention concerns a control valve for use in a vehicle anit-lock braking systm adapted to control the application of pressurized brake fluid to at least one selected vehicle brake. The valve includes an outer housing having an inlet coupled to receive pressurized brake fluid from the vehicle master cylinder and an outlet coupled to supply pressurized brake fluid to the selected vehicle brakes. A passageway is formed in the housing for connecting the inlet to the outlet. A normally open isolation valve is located in the passageway and is utilized to control the flow of fluid through the passageway between the inlet and the outlet. When an incipient wheel lock condition is detected, the isolation valve can be closed to prevent a further increase in pressure to the controlled brakes and to hold the pressure supplied to the controlled brakes at a relatively constant level.

Abstract: A vehicular skid control system for relieving the brake pressure when an incipient skid condition is sensed. The system includes a combined check and bleed valve that controls the flow of hydraulic actuating fluid from a master cylinder to the wheel brakes. An expansion chamber is positioned in the fluid circuit between the check and bleed valve and the wheel brakes. An ancillary source of fluid pressure, such as a power steering pump, normally holds the expansion chamber at a minimum volume condition and holds the check and bleed valve open for normal brake operation. When an incipient skid condition is sensed, the expansion chamber is permitted to increase in volume and the combination check and bleed valve is closed. Closure of the check and bleed valve isolates the master cylinder from the wheel brakes and prevents the application of further pressure to the wheel brakes. Expansion of the expansion chamber relieves the existing pressure in the wheel brakes to prevent skidding.