ELECTROMECHANICAL LATCHING ACTUATOR

• US 3,772,540 A
• Filed: 07/19/1972
• Issued: 11/13/1973
• Est. Priority Date: 07/19/1972
• Status: Expired due to Term

• Current Assignee: Glendon M. Benson
• Original Assignee: Glendon M. Benson
• Inventors: Benson, Glendon M.
• Primary Examiner(s): Goldberg, Gerald
• Application Number:
  US05/273,062
• Time in Patent Office: 482 Days
• Field of Search: 310/12,13,14,24,30,34,36,38,156
• US Class Current: 310/14
• CPC Class Codes: H01F 7/122 by permanent magnets H01F7/1615, H01F7/1646 take precedence
• CPC Class Codes: H01F 7/124 by mechanical latch, e.g. detent
• CPC Class Codes: H01F 7/145 Rotary electromagnets with variable gap with fixed gap or torque motors H02K26/00
• CPC Class Codes: H01F 7/1615 Armatures or stationary parts of magnetic circuit having permanent magnet
• CPC Class Codes: H02K 37/18 of homopolar type
• CPC Class Codes: H02K 41/065 Nutating motors

Abstract

An electromechanical latching actuator for producing linear or rotary motion. The device includes one or more sets of permanent magnets and electric coils which annul and flux switch a magnetic field between adjacent magnetic poles thereby sequentially generating a force or torque that can be coupled to a suitable load. A fluid valve coupled to such actuator.

Claims

1. In an actuator of the type that has a housing and a driving element supported in said housing for movement between a first position and a second position, an improved system for controlling the movement and position of said element with respect to said housing, said system comprising a first magnetic member attached to the driving element, a second magnetic member rigid with said housing and arranged to form a magnetic circuit path with said first magnetic member, said magnetic circuit having a vairable reluctance first air-gap therein between said first and second magnetic members which first air-gap is relatively small in said first position, a permanent magnet interposed in said magnetic circuit path to establish in said magnetic circuit path a latching flux for latching said driving element in said first position relative to said housing, said permanent magnet having a magnetic length along the circuit path that is less than the square root of the transverse area of the circuit path, at least one electric coil fixed within said housing circumscribing at least one of said magnetic members, said coil producing a magnetic flux in resonse to electrical excitation thereof that opposes and nullifies the latching flux produced in said magnetic circuit by said permanent magnet to permit movement of said driving element relative to Said housing away from said first position thereby to increase the reluctance of said first air-gap, and a third magnetic member spaced from said second magnetic member and corresponding to said second position and being arranged to form with said permanent magnet and said first magnetic member a second latching flux path for latching said driving element in said second position.

2. An actuator according to claim 1 wherein said permanent magnet is attached to first magnetic member for movement therewith.

3. An actuator according to claim 1 wherein said permanent magnet is attached to said housing and said second magnetic member.

4. An actuator according to claim 1 wherein said permanent magnet is of annular form and defines a central opening and wherein said first magnetic member has a shape substantially similar to said opening and resides therein to define a low reluctance path therebetween.

5. In an electromagnetic latching actuator of the class having permanent magnet means for producing magnetic flux in at least two variable reluctance parallel magnetic circuits, electric coil means for switching said permanent magnet flux between said magnetic circuits, a movable high permeability element that flux links said magnetic circuits and that is moved by said flux switching so as to vary reluctance in said magnetic circuits, and means for attaching movable objects to said movable element, the improvement comprising means forming at least two variable reluctance magnetic circuits with variable air-gaps in which a permanent magnet having a short magnetic length and a large magnetic area is in series with said magnetic circuits, at least one electric coil means which alternately switches the permanent magnet induced flux between said magnetic circuits by being energized with alternating electrical voltage polarity without switching flux direction in the permanent magnet, and a movable high permeability element that flux links said magnetic circuits and that is moved by said flux switching so as to increase the reluctance of the magnetic circuit to which it was latched to and to decrease the reluctance of the magnetic circuit toward which it is attracted and subsequently latched to with said latching provided solely by the permanent magnet induced flux so that said movable element with said attached movable objects is unlatched from one position and is attracted to and passively latched at another position.

6. An electromagnetic latching actuator in accordance with claim 5 comprising two parallel magnet circuits with variable air-gaps in which a radially poled toroidal permanent magnet having a short magnetic length and a large magnetic area is in series with said magnetic circuits, an electric coil for each magnetic circuit which alternately switches the permanent magnet induced flux between said magnetic circuits without switching flux direction in the permanent magnet, the two electric coils being series energized with alternating voltage polarity, a movable high permeability element that flux links said magnetic circuits and that is moved by said flux switching so as to increase the reluctance of the magnetic circuit too which it was latched to and to decrease the reluctance of the magnetic circuit toward which it is attracted and subsequently latched to with said latching provided solely by the permanent magnet induced flux.

7. An electromagnetic latching actuator in accordance with claim 6 in which the permanent magnet is integral with the movable high permeability element.

8. An electromagnetic latching actuator in accordance with claim 6 in which the permanent magnet is integral with the common segment of the two stationary parallel magnetic circuits.

9. An electromagnetic latching actuator in accordance with claim 5 comprising two parallel magnetic circuits with variable air-gaps in which a radially poled toroidal permanent magnet having a short magnetic length and a large magnetic area is in series with said magnetic circuits, an electric Coil mounted in one magnetic circuit hich alternately switches the permanent magnet induced flux between said magnetic circuits without switching flux direction in the permanent magnet, a movable high permeability element that flux links said magnetic circuits and that is moved by said flux switching so as to increase the reluctance of the magnetic circuit to which it was latched and to decrease the reluctance of the magnetic circuit toward which it is attracted and subsequently latched to with said latching provided solely by the permanent magnet induced flux.

10. An electromagnetic latching actuator in accordance with claim 5 comprising a stator including at least three pairs of variable reluctance parallel magnetic circuits arranged in a circular array with each said circuit pair having two electric coils with one coil of each said circuit pair mounted in a planar circumferential circular array and with the second coil of each said circuit pair colinear with said first coil and mounted in a planar circumferential circular array parallel to and concentric with the first planar circular array but separated by a fixed axial distance wherein fixed axial distance is maintained by an annular ring of high permeability material and a rotor including a radially poled permanent magnet segment having a short magnetic length and a large magnetic area and means attached to said permanent magnet for forming a common return magnetic circuit in series with said magnetic circuit pairs and within said fixed axial distance, said rotor being in the form of a nutating wheel that acts as the movable high permeability element which is splined to and nutates about a splined shaft whose axis is normal to plane of said circular array, so that said wheel nutates in response to the sequential energization of diametrically opposite said electric coils so as to nutate said nutating wheel thereby rotating said output shaft.

11. An electromagnetic latching actuator in accordance with claim 10 in which said nutating wheel has a toothed flange and said stator has a gear thereby forming a nutating gear which nutates by engaging said wheel with said gear, said gear being coplanar to said circular array and said gear having a different number of teeth than said nutating wheel.

12. An electromagnetic latching actuator in accordance with claim 5 comprising a stator that includes first and second substantially identical sections, each said section including a toothed ring having inward extending teeth that are of uniform circumferential extent and are spaced from one another by an equal extent to define a space between each tooth that is equal in circumferential extent to that of the tooth, an electric coil disposed in each space and circumscribing the ring so that a magnetic path between adjacent teeth passes through the portion of the ring that is circumscribed by said coil, said first and second stator sections being joined to one another so that the coils of first section reside in axial alignment with the teeth in the second section, and a rotor supported for rotation within the toothed rings of said stator, said rotor having a plurality of permanent magnets at the periphery thereof, said permanent magnets each having a circumferential extent equal to that of the teeth on said stator and an axial extent at least as great as that of the combined stator sections, a magnetic wedge shaped spacer between each said permanent magnet, said spacer having a circumferential extent equal to that of the permanent magnets and the teeth, so that opposite energization of the coils in the first stator section and the coils in the second stator sections causes rotation of said rotor by an increment equal to the circumferential extent of the teeth.

13. An actuator in accordance with claim 5 in combination with a valve body, means for connecting the valve body to said moveable element, a valve seat mounted in alignment with said valve body and positioned with respect thereto so that the valve body is latched againSt said seat at one position of the actuator and latched in spaced apart relation to the seat in the other position of the actuator.

14. An actuator according to claim 13 wherein said valve body connecting means comprises a tubular resilient member, said tubular member having a plurality of diametrically opposed pairs of excisions, the excisions of adjacent pairs being circumferentially offset from one another.

15. An actuator according to claim 13 in combination with a rod attached to said moveable element, a conductive spring washer attached to said rod, a first pair of contacts disposed so as to be bridged by said spring washer at one position of said actuator and a second pair of contacts disposed so as to be bridged by said spring washer at the other position of said actuator.

16. An actuator according to claim 5 in combination with a rod attached to said moveable element, a conductive member attached to aid rod, a first pair of contacts disposed so as to be bridged by said conductive member at one position of said actuator and a second pair of contacts disposed so as to be bridged by said conductive member at the other position of said actuator.