Abstract: An improved absolute position detection method is provided for a stroke sensing cylinder which includes a magnetic scale detecting step for obtaining a plurality of sine wave form voltages having different phases using a magnetic sensor unit in accordance with a driving operation of the cylinder. A wave form generation step is also provided for converting the sine wave form voltage obtained in the magnetic scale detection step into a square wave form and generating a triangle wave form having the same period as the thusly converted square wave form. A first absolute position value detection and stroke direction judging step is then provided for judging a first absolute position value and stroke direction of the cylinder using a pair of square and triangle wave forms generated in the wave form generation step.

Abstract: A structure for mounting an actuating rod stroke sensor to a hydraulic cylinder is disclosed. The sensor mounting structure has a sensor holder which is mounted to a predetermined portion of a cylinder head. A circuit board is tightly set in the sensor holder and holds the stroke sensor in the sensor holder. The above structure improves the operational precision of the stroke sensing operation and effectively fixes the sensor to the cylinder. The structure also protects the stroke sensor from the frictional heat generated during the reciprocating motions of the actuating rod, thereby lengthening the expected life span of the stroke sensor.