Electric stroke sensor for use in primary piston of tandem master cylinder of e.g. hydraulic brake booster system in vehicle, has electrical circuit coupled to sleeve and ground to measure capacitance of capacitor formed by electrodes

摘要

The sensor (160) has a plastic dielectric sleeve (161) surrounding a primary piston (120) from an inlet side of a body (101) of a tandem master cylinder (100). The primary piston slides in the sleeve based on activation of the cylinder so as to form a capacitor plate. The plate covers an electrically conductive outer layer (163) of the sleeve. An electrical circuit is connected to the outer layer of the sleeve and ground for measuring capacitance of a capacitor formed by electrodes.