Husco International, Inc.

Parker-hannifin Corporation

Kayaba Industry Company, Ltd.

Rollin C Christianson

Raud A Wilke

Leif Pedersen

Clyde Bennett Stevens

Christopher John Kolbe

Hiroshi Kobata

An displacement measurement device and associated method where displacement measurements of a movable member are obtained by an electromagnetic field sensor that need not move relative to the magnet or other electromagnetic field source. The electromagnetic field sensor senses disruptions in the electromagnetic field caused by movement of the movable member to provide an output indicative of the position of the actuator.

Displacement measurement device

Cushion chambers () disposed in the vicinity of both ends of a hydraulic cylinder () to throttle inflow or outflow of an operating oil caused by a piston () moving close to a piston stroke end, pressure sensors () to detect pressures in the cushion chambers (), and a control valve () disposed in a passage to supply/drain the operating oil to and from oil chambers () of the hydraulic cylinder () for varying a flow amount of the operating oil are provided. A controller () varies an opening degree of the control valve () within a piston stroke end range based upon outputs of the pressure sensors (), adjusts a cushion pressure and controls a moving speed of the piston (). Thereby deceleration degrees of the piston () can be freely adjusted within the piston stroke end range based upon a change of the operating conditions of the hydraulic cylinder ().

Control apparatus for hydraulic cylinder

A hydraulic control valve has a spool slidably received in a bore of the valve body. The spool can be moved in opposite directions to control flow fluid to and from a pair of workports. A sensor assembly has a coupling attached to the spool and holds a permanent magnet. A Hall effect sensor produces an electrical signal indicating the position of the permanent magnet and thus the spool. A double acting spring assembly biases the coupling and spool with respect to the housing of the sensor when the spool moves in one direction, and biases the coupling and spool with respect to the valve body when the spool moves in the other direction.

Hall effect valve spool position sensor

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Delafield, WI, United States of America

Rollin C Christianson