Monophase electromagnetic rotary actuator of travel between 60 and 120 degrees

• US 5,334,893 A
• Filed: 02/26/1993
• Issued: 08/02/1994
• Est. Priority Date: 02/28/1992
• Status: Expired due to Term

• Current Assignee: Moving Magnet Technologies SA (Société industrielle de Sonceboz SA)
• Original Assignee: Moving Magnet Technologies SA (Société industrielle de Sonceboz SA)
• Inventors: Prudham, Daniel, Oudet, Claude
• Primary Examiner(s): Voeltz, Emanuel T.
• Assistant Examiner(s): JONES, JUDSON
• Application Number:
  US08/022,916
• Time in Patent Office: 522 Days
• Field of Search: 310/36, 310/15, 310/17, 310/37, 310/38, 310/39, 318/122, 318/123, 318/124
• US Class Current: 310/38
• CPC Class Codes: H01F 7/145 Rotary electromagnets with variable gap with fixed gap or torque motors H02K26/00
• CPC Class Codes: H02K 26/00 Machines adapted to function as torque motors, i.e. to exert a torque when stalled

Abstract

This invention relates to a monophase electromagnetic rotary actuator of angular travel between 70/N and 110/N degrees exhibiting a high torque/mass ratio and a torque that is approximately independent of the angular position of the rotor. A relation between the magnetized width Y_a measured on the mean diameter of the magnets, the width of the angular arc C through which the rotor passes on the mean diameter of the magnets, the width S measured on the mean diameter of the magnets between two adjacent stator poles, the radial length of the magnets L, and the constant length E of the air gap is:

Y.sub.a =C+S +2 E'"'"'

where E'"'"' is between E/2 and E. Furthermore, C+2 E'"'"'/E >6 and L/E>0.75.

Claims

1. A monophase electromagnetic rotary actuator of angular travel between 70/N and 110/N degrees comprising:

a rotor exhibiting 2N magnets, N being equal to 1 or to 2, and a core of a material of high magnetic permeability;

a stator exhibiting two pole pieces joined by at least one connecting part supporting at least one coil, the two pole pieces and the core of the rotor defining between them an air gap of constant length E, wherein the 2N magnets have a reversible permeability close to 1 and wherein a relation between a magnetized width Y_a of one of the 2N magnets measured on a mean diameter of the magnets, a width of an angular arc C through which the rotor passes on the mean diameter of the magnets, a width S measured on the mean diameter of the magnets between two adjacent stator poles and a constant length E of the air gap is

space="preserve" listing-type="equation">Y.sub.a =C+S+2 E'"'"'

where;

E'"'"' is between E/2 and E

and wherein;

space="preserve" listing-type="equation">C+2 E'"'"'/E

and wherein

space="preserve" listing-type="equation">L/E>

0.75;

L designating a radial length of one of the 2N magnets;

to obtain a high torque/mass ratio and a torque that is approximately independent of the angular position of the rotor.

2. The monophase electromagnetic rotary actuator according to claim 1, wherein the 2N magnets of the rotor comprise radially magnetized magnets in a shape of cylindrical tiles with the peripheral width Y_a measured on the mean diameter D_m of the magnets, wherein said 2N magnets extend over angular sections between 80/N degrees and 130/N degrees, and wherein the stator part has 2N pole pieces cooperating with the magnet, connected by a U-shaped connecting part.

3. The monophase electromagnetic rotary actuator according to claim 1, wherein the 2N magnets of the rotor comprise transversely magnetized magnets in a shape of disk sectors extending over angular sections between 80/N and 130/N degrees, and wherein the stator part has 2N pole pieces cooperating with the magnet, connected by a U-shaped connecting part.

4. The monophase electromagnetic rotary actuator according to either of claims 2 or 3, wherein a median section plane of the U-shaped connecting part is perpendicular to an axis of rotation of the rotor.

5. The monophase electromagnetic rotary actuator according to either of claims 2 or 3, wherein a median section plane of the U-shaped connecting part is parallel to a plane of symmetry of the pole pieces and contains an axis of rotation of the rotor.

6. The monophase electromagnetic rotary actuator according to any one of claims 1-3, wherein the stator part has two coils each surrounding one of the two pole pieces, said two pole pieces being joined by at least one connecting part.

7. The monophase electromagnetic rotary actuator according to any one of claims 2 or 3, wherein the two pole pieces of the stator are joined by two diametrically opposite connecting parts each carrying an excitation coil.

8. The monophase electromagnetic rotary actuator according to any one of claims 1-3, wherein the width S measured on the mean diameter D_m of the magnets between two consecutive stator poles is between E/2 and E, and wherein the peripheral width Y_a of the magnets measured on the mean diameter D_m of the magnets is:

space="preserve" listing-type="equation">Y.sub.a =C+2 E'"'"'+S≈

C+3 E'"'"',

and wherein the two magnets extend over arcs less than 180°

/N.

9. The monophase electromagnetic rotary actuator according to any one of claims 1-3, wherein a width Y_s of a stator pole measured on the mean diameter D_m of the magnets is equal to:

space="preserve" listing-type="equation">Y.sub.s =C+2 E'"'"'+T ≈

C+3 E'"'"',

where T designates a transition zone between two adjacent magnets of the rotor, T being less than E,

and wherein the 2N magnets extend over arcs less than 180°

/N.

10. The monophase electromagnetic rotary actuator according to either of claims 2 or 3, wherein a section of the stator connecting part is approximately equal to C×

Z, where;

Z designates a height of the magnets, measured according to a dimension perpendicular to their displacement and to their direction of magnetization.

11. The monophase electromagnetic rotary actuator according to either of claims 2 or 3, wherein the stator structure comprises two parallel lamination packets, said packets being assembled perpendicularly, the first of said lamination packets defining the stator pole pieces comprising laminations placed perpendicularly to the axis of rotation, the second lamination packet defining the U-shaped connecting part and comprising laminations parallel to a plane of symmetry of the stator passing through the middle of the stator poles and containing the axis of rotation of the rotor and passing through the stator poles, the laminations exhibiting cutouts for the relative fitting and positioning of said lamination packets.

12. The monophase electromagnetic rotary actuator according to claim 11, wherein the first lamination packet defining pole pieces comprises two series of pole laminations with a shape that is symmetrical in relation to the median plane of the actuator and has at each end a single lamination corresponding to said pole laminations joined by 2N saturable isthmuses.