Electrical generator or motor structure – Dynamoelectric – Rotary
Patent
1991-02-19
1994-03-29
Skudy, R.
Electrical generator or motor structure
Dynamoelectric
Rotary
310 17, 310254, 310266, H02K 106, H02K 127, H02K 2112
Patent
active
052988252
DESCRIPTION:
BRIEF SUMMARY
This invention pertains to a single phase electro-magnetic actuator which is equipped with a rotor that is arranged inside an armature of a statoric structure comprised of an initial magnetic circuit which includes 2N poles and at least one excitation coil, and a second magnetic circuit. The magnetic circuits are executed with a material that has high magnetic permeability. The rotor displays a thin magnetized section which is comprised of 2N pair of thin magnetized poles crosswise in opposite direction. The magnetization is nearly uniform and extends along a length Y.sub.A that is measured according to the displacement path. These types of actuators are designed especially for rotating actuators or even control panel indicators. These actuators display the peculiarity of possessing a large area wherein the force is constant. Hence, it is possible to execute actuators which possess high reproducibility and extremely high angular accuracy through servo-control. These actuators display nevertheless a disadvantage for applications where advanced miniaturization is sought. Indeed, the constant force zone only exists, according to what we learn from the state of the art, when the magnetic circuit is closed. For this to occur, the initial magnetic circuit and the second magnetic circuit are united in all instances by a magnetic part which is placed outside the path traveled by the mobile organ. This magnetic part which unites the magnetic circuits must display a size that is sufficient to enable the passage of magnetic flows and therefore embodies an additional prejudicial cumbersomeness.
The purpose of this invention is to execute a single phase electro-magnetic actuator which displays the same reproducibility and angular accuracy qualities, at reduced overall dimensions.
This invention is characterized by the fact that the two magnetic circuits are connected solely by non magnetic braces, and in that N is less than ##EQU1## E being the thickness of the distance armature between the two magnetic circuits and D being the average diameter of the statoric structure. Under those circumstances, the applicant was able to execute, surprisingly and contrary to any lesson derived from the state of the art, an electro-magnetic actuator in which an extended zone exists at a constant force.
According to an initial implementation mode, the actuator includes a tubular rotor which is radially magnetized and that displays 2N pairs of staggered poles, the ratio between the thickness E of the armature and the length Y of said poles being less than 0.25. The statoric structure is comprised of an initial magnetic circuit that surrounds the rotor and displays 2N polar sections which are excited by electrical coils, and by a second magnetic circuit comprised of a full cylinder placed inside the rotor, the rotor and the two magnetic circuits being coaxial, we can execute, by selecting very low height cylinders, extremely flat indicators or actuators with very low obstruction.
According to an advantageous variant, the pairs of magnetic poles of the rotor are attached to the second magnetic circuit. The second magnetic circuit thus comprises a support for the rotor, which is fairly fragile, and can support the utilization axis of the actuator.
According to another implementation mode, the rotor is comprised of a thin disk which is divided into 2N angular sectors that are magnetized crosswise in staggered directions, whereby the rotor can turn around a central axis between an initial magnetic circuit that is comprised of 2N angular sectors surrounded by excitation coils and by a second magnetic circuit comprised of a disk that is coaxial with the rotor and the second magnetic circuit.
Preferably, the thickness of the second magnetic circuit is at least equal to ##EQU2## BO represents the induction of the magnet, B.sub.s at represents the saturation induction inside the iron, D represents the outer diameter of the magnetized part of the magnet, d represents the internal diameter of the magnetized part located inside the armature, and D.s
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Oudet Claude
Prudham Daniel
Haszko D. R.
Moving Magnet Technologies SA
Skudy R.
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