DEVICE COMPRISING A CYLINDER, A PISTON MOVABLE THEREIN AND A PISTON POSITION TRANSDUCER ARRANGED WITHIN THE CYLINDER

摘要

An apparatus containing a cylinder with a piston displaceably guided therein and positionally adjustable by a hydraulic fluid medium. A capacitive measuring transducer is arranged in the cylinder. The measuring transducer comprises a tube attached at the piston and arranged in a longitudinal opening thereof. The tube is electrically conductively connected with the cylinder. Apart from the tube, the measuring transducer further comprises a rod protruding into the tube and insulatingly secured at the cylinder. This rod is connected by means of an electrical bushing or lead with the input of an electronic unit attached externally at the cylinder. The electronic unit comprises an oscillator having a connection electrically coupled with the cylinder and a connection coupled with the non-inverting input of a capacitive feedback differential amplifier. The inverting input of the differential amplifier is electrically connected with the rod which is secured so as to be electrically insulated at the cylinder.