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Moving Magnet Technologies (s.a.)

Mmt Sa

Moving Magnet Technologie Sa

Matsushita Electric Works, Ltd.

Societe De Recherches En Matiere De Micromoteurs Electriques

Claude Oudet

Daniel Prudham

Pierre Gandel

Didier Frachon

Danielle Regnier

Norbert Veignat

Gilbert Drey

Masao Tanahashi

Yasuo Ibuki

Ryo Motohashi

Toyokatsu Okamoto

Hidetoshi Amaya

Takio Maekawa

Christophe Besson

Georges Stcherbatcheff

Jean-Fran&ccedil;ois Urwyler

Yves Guerin

Daniel Prudhamm

Didier Angleviel

The invention concerns a position sensor, designed in particular for detecting a steering column torsion, consisting of a first magnetic structure including a plurality of magnets and a second magnetic structure including two ferromagnetic rings () having a plurality of teeth () and defining an air gap wherein is placed at least a magneto-sensitive element (), the two magnetic structures being respectively integral with two parts in relative rotation. The invention is characterised in that the two ferromagnetic rings () are nested and have each a substantially tubular part forming axially oriented teeth () connected by a flux-closing zone (), the detecting air gap being delimited by said flux-closing zones.

Position sensor, designed in particular for detecting a steering column torsion

An electromagnetic device, specifically a linear or rotary single- or multi-phase motor or generator comprising, for each phase, at least two relatively-movable sets of teeth of soft magnetic material, one set of teeth being associated with the stator and the other with the rotor, the size of the device being such as to enable it to generate a maximum magnetic potential U of at least 1.7&times;10 J/&mgr; ampere turns. The width E of the minimum air-gap between teeth of the rotor and of the stator as measured in the direction perpendicular to the degree of freedom is approximately equal to or greater than 0.7 &mgr; U /J where &mgr; is the permeability of free space, U is the maximum generated magnetic potential difference for causing the magnetic field to pass through the air-gap E, and where J is the maximum polarization of the soft magnetic material used for making the teeth.

Motor or generator type electromagnetic devices

The invention concerns a magnetic position sensor for delivering an electric signal proportional to the position, including of a mobile part having at least a thin permanent magnet movable in a main air gap. The air gap is defined by two ferromagnetic parts and, the ferromagnetic parts defining between them a secondary air gap including a sensor sensible to magnetism. The mobile part is arranged such that penetration on the magnetic part into the main air gap is partial over part of the useful travel so that the sensor sensible to magnetism delivers a signal proportional to the degree of engagement of the magnetic parts in the main air gap.

Magnetic sensor for delivery of an electrical signal proportional to position

An electromagnetic actuator including a fixed stator having two poles. The stator includes one or two excitation coils. The actuator further includes a mobile part provided with thin permanent magnets magnetized along an air gap direction. The mobile member includes at least two independent elements which are each mobile along directions parallel to the air gap plane intersection and the fixed stator median plane, in opposite directions. Each of the mobile parts has three thin magnets alternately magnetized, which are either integral or not with a yoke made of soft material. The thin magnets of the mobile elements are magnetized along a direction opposite to the corresponding thin magnets of the second mobile element or of the adjacent element, the yokes defining with a fixed stator part a yoke.

Electromagnetic actuator with two mobile parts in phase opposition

A linear uniphase polarized electromagnetic actuator. The actuator includes a coiled stator and one part which is movable in the direction OX with the useful travel of Xc. The movable part is moved according to the current traveling in the coil and the direction of travel depends on the direction of the current. The movable part includes a yoke of soft magnetic material having at least one magnet coupled with the yoke. The magnet is partially set inside a cavity of the mobile yoke on the side of the stator poles at a depth e such that 0.1 L<e<0.9 L, where E is the distance measured perpendicularly to OX between the stator poles and the cavity end pole.

Linear actuator

This invention pertains to an incremental sensor of position and/or speed, of the type which includes a moving component made of a soft material that has at least one moving tooth in a direction OZ with respect to a permanent magnet magnetized along the direction OY, which is approximately perpendicular to the OZ axis, and a probe which is sensitive to the direction and strength of the magnetic field, such as a Hall-effect gaussmeter, arranged in the air gap between the magnet and the tooth of the moving component so that its axis of greatest sensitivity is approximately oriented along the OZ axis. The Hall-effect gaussmeter is located near a singular point of the OZ axis where the average value of the magnetic field is weak and preferably less than .+-.20 mT and approximately equal to the average value of the alternating field of the integrated circuit connected to the Hall-effect gaussmeter. The permanent magnet can also be laser trimmed to achieve the desired operation in the Hall-effect gaussmeter.

Incremental sensor of speed and/or position for detecting low and null

This invention relates to a position sensor featuring a stator defining an air gap inside of which a mobile magnet integral with a coupling shaft moves. The sensor features a Hall probe for measuring the variation of the induction in an air gap. The stator is formed of a first stationary part and a second part which is either stationary or mobile, the two parts defining between them a main air gap in which the part of the mobile element moves. The mobile element exhibits at least two adjacent thin parts magnetized crosswise in alternate directions, the magnetized parts being made of a material exhibiting in the entire working area a practically linear demagnetization characteristic and reversible permeability close to that of the air. The stationary part exhibits at least two secondary air gaps approximately perpendicular to the main air gap in which the mobile element moves. The Hall probe is housed in one of the secondary air gaps. The L/E ratio is greater than 6, L designation the width of a magnetic pole and E designating the width of main air gap.

Magnetic position and speed sensor having a hall probe

Monophase, short travel, electromagnetic actuator having a good electric

A movable member of the present driving device comprises a magnetized part, or more than one magnetized parts having all the same direction of magnetization, which is perpendicular to the direction of movement. Each magnetized part is moving in at least two air-gaps of a closed magnetic circuit coupled with en energizing coil. The material of the magnetized parts has a linear demagnetization characteristic up to temperatures at least equal to 100.degree. C. and at least up to a negative value of the flux density equal, in absolute value, to 0.5 times the remanence of the magnetic material. The driving device is dimensioned so that the mean operating point of each magnetized part lies at a flux density value smaller than 0.5 times the value of the remanence of the magnetic material used. The volume of magnetic material can be substantially reduced for a given force or torque to be delivered.

Electromagnetic driving device with a movable permanent magnet

This invention pertains to an incremental sensor of position and/or speed, of the type which includes a moving component made of a soft material that has at least one moving tooth in a direction OZ with respect to a permanent magnet magnetized along the direction OY, which is approximately perpendicular to the OZ axis, and a probe which is sensitive to the direction and strength of the magnetic field, such as a Hall-effect gaussmeter, arranged in the air gap between the magnet and the tooth of the moving component so that its axis of greatest sensitivity is approximately oriented along the OZ axis. The Hall-effect gaussmeter is located near a singular point of the OZ axis where the average value of the magnetic field is weak and preferably less than .+-.20 mT and approximately equal to the average value of the alternating field of the integrated circuit connected to the Hall-effect gaussmeter.

A magnetic position sensor having a thin tubular-shaped permanent magnet that is integral with a coupling shaft. The permanent magnet is mobile in rotation in a main air gap between two parts made of a soft magnetic material. One of the parts is formed by a stator having a secondary air gap in which a Hall probe is housed. The stator is placed coaxially on the inside of the tubular-shaped permanent magnet, with the other magnetic part including a coaxial tubular yoke with the tubular-shaped permanent magnet and defining, with the stator, a cylindrical main air gap.

Magnetic position sensor with hall probe formed in an air gap of a stator

A linear oscillating motor capable of assuring a consistent and effective feedback control of keeping a constant oscillation amplitude with varying load conditions. The linear oscillating motor comprises an oscillator carrying a permanent magnet, and a stator with an electromagnet. The electromagnet is supplied with an electric power to develop an electromagnetic drive force of moving the oscillator in a linear direction relative to the stator. A spring is provided to apply a restoring force to the oscillator for providing a linear oscillating motion to the oscillator. A photo-sensor monitors the linear motion of the oscillator and outputs a signal to a reverse-point detector which determines right and left reverse points of the oscillator. A controller applies the electric power to the electromagnet at the drive points respectively defined subsequent in time to the reverse points and in a varying amount for keeping a constant oscillation amplitude of the oscillator. The photo-sensor outputs a train of pulses appearing each time the oscillator passes its oscillation center. The reverse-point detector determines the reverse points based upon a time period between the two preceding pulses. Since the photo-sensor can monitor an oscillation cycle of the oscillator without being affected by the magnetic field developed by the electromagnet for driving the oscillator, it provides a reliable basis for accurately determining the reverse points and therefore the drive points. Accordingly, the driving force can be applied at an optimum timing to make the feedback control accurately and reliably.

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Besancon, France

Claude Oudet