Fluid power assist method and apparatus

摘要

An apparatus for driving a piston with fluid power is disclosed. The apparatus includes a fluid filled cylinder having an inner and an outer wall and defining a longitudinal axis. A piston is slidably positioned in the cylinder to move along a path of travel parallel to the longitudinal axis. A magnet is coupled to the piston for movement with the piston, The apparatus further includes a pump in fluid communication with the cylinder and being selectively actuated to intermittently pump pressurized fluid into the cylinder to apply force to and move the piston in a first direction along the path of travel. A fluid releasing apparatus is provided to release fluid from the cylinder to move the piston in a direction opposite the first direction. The apparatus also includes a Hall effect sensor situated at a location along the outer wall of the cylinder for sensing a position of the piston by sensing a magnetic field associated with the magnet at the location of the sensor. Control circuitry is coupled to an output from the Hall effect sensor for actuating the pump.