HYDROPNEUMATIC PISTON ACCUMULATOR

A hydropneumatic piston accumulator, with an accumulator housing (1), which comprises a cylindrical tube (3) defining a longitudinal axis (11), wherein the cylindrical tube (3) is closed at both ends by a housing cover (5, 7) at each end and wherein a piston (9) is longitudinally movable in the cylindrical tube (3) and, in the housing, separates a working chamber (13) for a compressible medium, such as a working gas, from a working chamber for an incompressible medium, such as hydraulic fluid, and with a displacement measuring device for determining the position of the piston (9) in the housing in a contact-free manner. The invention is characterised in that the displacement measuring device comprises a non-magnetic measuring tube (29), which extends along the longitudinal axis (11) from one housing cover (5) to the other housing cover (7) through a passage (31) formed in the piston (9) and is sealed against the interior of the housing (1), and in that in the tube (29) a position sensor (57) is movably guided and follows the piston movements in the measuring tube (29) using a magnetic force acting between the piston sensor (57) and the piston (9), and in that a transmitter/receiver (65) for the displacement measuring device is positioned on one of the housing covers (5, 7) and emits a measurement beam through the open end (25, 26) of the measuring tube (29) to the position sensor (57) and receives reflected radiation from same.