Piston-cylinder arrangement with a travel-measuring sensor

Abstract

The invention relates to a piston-cylinder arrangement, in particular for use in a hydraulic system for activating a clutch in a motor vehicle, having a piston which is arranged in an axially movable fashion in the cylinder, wherein an inductive sensor is arranged on the cylinder and has at least one primary coil for generating a magnetic field and at least two secondary coils which are arranged inside the primary coil and have the purpose of sensing the target positions, wherein the coil axes are arranged perpendicularly with respect to the direction of movement of the piston, and the secondary coils are formed with crossed windings, wherein a first secondary coil is embodied in such a way that a first loop covers approximately a quarter of the sensor length, a second adjoining loop; covers approximately half the sensor length and a third adjoining loop covers approximately the remaining quarter of the sensor length, and a second secondary loop is embodied in such a way that a first loop covers approximately the first half of the sensor length, and a second loop covers approximately the second half of the sensor length, characterized in that at least two targets composed of an electrically conductive material are arranged on the piston, and the targets are spaced apart axially from one another and the targets have different electrical conductivity and / or are of a different size, and the sensor has at least one assignment coil which extends over the entire sensor length.

Description

technical field

[0001] The invention relates to a piston-cylinder arrangement, in particular for use in a device for actuating a clutch in a motor vehicle, which has a sensor for determining the position of the piston in the cylinder. Background technique

[0002] Early recognition of the driver's wishes is advantageous, for example, in order to maintain a customary driving style in a motor vehicle with a stop-start system. A displacement sensor, for example in the clutch master cylinder, fulfills this requirement and additionally assumes an auxiliary function, which is to be performed, for example, by an electrical position switch in the pedal. Furthermore, such sensors use the Hall effect or are implemented with one or more external coils in which a voltage is induced by a magnet attached to the piston. What all of these systems have in common is that they rely on magnets fixed to the piston for maneuvering. Since considerable costs are incurred for the manufacture of th...

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