Fisher Controls International LLC

Fisher-rosemount Systems, Inc

Nile K Dielschneider

John Patrick Dilger

Donald Paul Pepperling

James Chester Hawkins

Ted Dennis Grabau

David Edward Woollums

Jerry Marvin Ceaser

Meredith D Miller

David E Woollums

John P Dilger

A magnet assembly is disclosed for use with a magnetic flux sensor to provide a position sensor adapted to detect a position of a moveable member. The magnet assembly comprises a magnet housing defining an inner surface. A magnet is provided that is sized for insertion into the magnet housing and adapted for movement with the moveable member, the magnet having a north pole and a south pole, wherein the magnet generates a magnetic flux. A centering ring is positioned between the magnet and the magnet housing, the centering ring including a biased wall acting to center the magnet in the magnet housing.

Self-centering magnet assembly for use in a linear travel measurement device

A displacement sensor includes a magnet assembly having a housing for mounting to one of first and second relatively moveable elements. A magnet assembly is mounted to one element and defines a longitudinal space having an axis along its length. The magnet assembly includes at least one magnet having a north and a south pole that supply fringing magnetic flux in the longitudinal space and a flux-shaping pole piece on each of the north and south poles. A magnetic field sensor assembly has a housing for mounting to the other of the first and second elements for movement along an axis in the space parallel to the magnet assembly. In one embodiment, each of the flux-shaping pole pieces has a pentagon shape in a plane of primary flux pattern, forming a first face confronting the longitudinal space between the first and second magnets. In another embodiment, the magnet is a cylindrical magnet adjacent the longitudinal space, and the first face of each flux-shaping pole piece is cylindrical and coaxial with the cylindrical magnet. Preferably, the pole piece has a frusto-conical face confronting the longitudinal space adjacent the cylindrical face.

Linearized magnetic displacement sensor

Fugitive emission sensing system

An electrical circuit and method for measuring small variations in a high frequency signal is disclosed. The circuit generates a coarse measurement of the input signal frequency and a reference signal having the same frequency as the frequency represented by the coarse measurement. The circuit measures the difference in frequency between the input signal and the reference signal, and adds the coarse measurement and the difference measurement to determine the frequency of the input signal. The circuit may be used in conjunction with a piezoelectric acoustic wave device and oscillator to provide an apparatus for accurately measuring low concentrations of a gas.

High frequency measuring circuit

A displacement sensor includes a magnet assembly having a housing for mounting to one of first and second relatively moveable elements. First and second magnets are mounted to the magnet assembly housing so that the north pole of one magnet confronts the south pole of the other magnet, and vice versa. The first and second magnets form a longitudinal space between them. A flux-shaping pole piece on each of the poles have configurations to sculpt fringing magnetic flux in the longitudinal space so that magnetic flux density in the longitudinal space varies substantially linearly along a line in the longitudinal space between the confronting poles of the magnets. A magnetic field sensor assembly has a housing for mounting to the other of the first and second elements. A magnetic flux sensor is mounted to the sensor housing on the line in the longitudinal space between the first and second magnets. In one embodiment, each of the flux-shaping pole pieces has a pentagon shape in a plane of primary flux pattern, forming a narrow face confronting the longitudinal space between the first and second magnets. The narrow face of each flux-shaping pole piece is wider across the primary flux pattern than along the length of the line in the longitudinal space.

Flux shaping pole pieces for a magnetic displacement sensor

A displacement sensor senses relative displacement between first and second members and includes a housing mounted to the first member. Magnet means having first and second pole tips is mounted to the housing. A flux sensor is mounted to the housing between the first and second pole tips. A target is mounted to the second member to form a flux path between the first and second pole tips having a reluctance that varies with displacement between the first and second members. The arrangement forms a first lossy flux path of fixed reluctance through the flux sensor and a primary flux path through the target. In one form the target has a surface configured to provide a gap height that varies with displacement. In another form the target has a surface configured to provide a target width that varies with displacement. The sensor may be used differentially by arranging two such sensors.

Growing community of inventors

Conrad, IA, United States of America

Nile K Dielschneider