LINEAR ACTUATOR AND POSITION SENSING APPARATUS THEREFOR

摘要

A linear actuator such as a hydraulic cylinder has linear position sensing apparatus. At least one magnet is provided in a recess in outer surface of the piston for generating a magnetic field that passes through the wall of the cylinder housing. A magnetic sensor arrangement determines the axial position of the piston relative to the housing and comprises at least a pair of magnetic sensor elements arranged at spaced apart locations along the external surface of the wall for sensing the strength of the magnetic field passing through the wall of the housing. The recess in the piston is axially positioned between the first and second end surfaces of the piston and the at least one magnet is disposed between axially spaced north and south pole pieces.