US 4,440,454 AGranted

Pressure control arrangement for vehicle braking system with antiskid control equipment

AssigneeITT Industries, Inc.

InventorsJuan Belart, Jochen Burgdorf, Dieter Kircher, Lutz Weise

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Abstract

An antiskid control arrangement of a hydraulic vehicle braking system includes a master cylinder device and a throttling valve device arranged between the master cylinder device and the brake pedal. The throttling valve device is incorporated in a circulating circuit which includes a hydraulic pump operated exclusively during antiskid control operation. During normal braking operation without antiskid control action, the braking system operates in a static manner. During antiskid control braking operation, the drive of the hydraulic pump is energized while the throttling valve device remains closed until the dynamic pressure generated by the hydraulic pump has risen to the level to the static pressure then prevailing in the working compartments of the master cylinder device. Thereafter, the throttling valve device opens to relieve excess pressure. The pressurized hydraulic fluid from the auxiliary energy source is fed from the secondary side to the working side of the master piston to operate the wheel brake actuating cylinders in a dynamic manner during the antiskid control operation. An annular positioning piston is provided which becomes effective only during operation in the antiskid control mode as an abutment for the throttling valve so that the brake pedal is brought into a defined position during the antiskid control operation. A shutoff valve which is controlled in response to the movement of the positioning piston is interposed in the return conduit and prevents escape of hydraulic fluid from the master cylinder device when the hydraulic pump is out of operation.

Claims17

Dependent claims

An arrangement for controlling the pressure of a hydraulic braking fluid supplied to wheel brake actuating cylinders interposed between supply and return conduits of a vehicle braking system provided with antiskid control equipment and with a supply reservoir in dependence on the position of a brake pedal, comprising a master cylinder device including a housing defining an elongated bore, and at least one master piston received in said bore for longitudinal movement in and opposite to a working direction and delimiting in said bore a working compartment for the hydraulic braking fluid that communicates with at least one of the supply conduits;

means for transmitting the brake pedal force to said master piston to move the same in said working direction and thus to pressurize the hydraulic braking fluid present in said working compartment;
an auxiliary source of a pressurized hydraulic braking fluid, means for admitting the pressurized hydraulic braking fluid from said auxiliary source into said working compartment only during antiskid control operation of the antiskid control equipment, including a circulating conduit for pressurized fluid;
and means for controlling the pressure in said circulating conduit, and a throttling valve interposed at the output of said circulating conduit and arranged between said brake pedal and said master piston to constitute at least a part of said transmitting means, and said throttling valve responsive to pressurized fluid from said circulating conduit for permitting flow from said circulating conduit only after the pressure in said circulating conduit has exceeded a value having a predetermined ratio to the brake pedal force to provide pressurized fluid from said admitting conduit to said working compartment.

Dependencies are inferred from the claim text.