Haldex Brake Corporation

Midland Brake, Inc.

Robert J McMullen

Roger D Hanaway

Joseph G Baalmann

Scot C Reeder

A system for electrically detecting different positions of a movable piston within a piston housing of a hydraulic system is provided. The system includes at least two electrically conductive pads mounted on the piston housing at different locations along the path of movement of the piston, an electrically conductive segment mounted on the piston housing along the path of movement of the piston adjacent the conductive pads, and an electrical coupler, such as a spring-loaded conductor, attached for movement with the piston to provide an electrical connection between each conductive pad and the conductive segment as the piston moves along within the piston housing. The system also includes an electronic control unit, which may be a microprocessor, coupled to each conductive pad and the conductive segment to detect electrical connection between each conductive pad and the conductive segment. Each electrical connection corresponds to a specific position of the piston.

System for electrically detecting piston positions in a hydraulic system

A hydraulic system for accommodating fluid pressure variations is provided. The system includes a housing for an actuating piston with the housing having a first end with a hydraulic fluid port and a second end. The actuating piston includes a body portion, having a face, and a rod portion. A first resilient member is confined between the actuating piston and the second end of the housing. A second resilient member is confined between the body portion and the face of the actuating piston. The face of the actuating piston is preferably a pressure accommodating piston which moves relative to the body portion of the actuating piston. Preferably, the second resilient member has a tension force greater than the tension force of the first resilient member. As the actuating piston moves against the bias of the first resilient member toward the second end of the housing in response to hydraulic fluid entering the housing through the fluid port, the movement of the actuating piston is limited by a stop. If there is an increase in hydraulic fluid pressure with the actuating piston in the stopped position, the additional pressure is accommodated by compression of the second resilient member.

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Kansas City, MO, United States of America

Robert J McMullen