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Coaxial Magnetic Actuator with Snap Action Rotary Motion

IP.com Disclosure Number: IPCOM000081023D
Original Publication Date: 1974-Mar-01
Included in the Prior Art Database: 2005-Feb-27
Document File: 3 page(s) / 73K

Publishing Venue

IBM

Related People

Vinal, AW: AUTHOR

Abstract

Fig. 1 illustrates a schematic cross-sectional view of a snap-action rotary motion actuator. The housing 1 is made from nonmagnetic material and preferably is made of molded plastic. A shaft 2 which may be of magnetic or nonmagnetic material, is supported in recesses 3 to allow rotation. Shaft 2 carries two fixed cylindrical magnets 4 and 5. A coaxial ring magnet 6 is placed about housing 1 and is free to move upwards and downwards in the axial direction, or it may be fixed in any desired position.

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Coaxial Magnetic Actuator with Snap Action Rotary Motion

Fig. 1 illustrates a schematic cross-sectional view of a snap-action rotary motion actuator. The housing 1 is made from nonmagnetic material and preferably is made of molded plastic. A shaft 2 which may be of magnetic or nonmagnetic material, is supported in recesses 3 to allow rotation. Shaft 2 carries two fixed cylindrical magnets 4 and 5. A coaxial ring magnet 6 is placed about housing 1 and is free to move upwards and downwards in the axial direction, or it may be fixed in any desired position.

Magnets 4, 5, and 6 are all punched or machined from a strip of PLASTIFORM* 1-H material. It is important that the magnets be machined from a strip of material oriented, such as shown in Fig. 4. Orientation notches, as shown, are provided in the magnetic parts during the machining operation, to control the orientation of these magnets with respect to one another when they are in place.

A stable configuration for each of the shaft magnets 4 and 5 in relation to the coaxial ring magnet 6 is shown in Fig. 5, in a plan view taken from above or below Fig. 1, with the magnet 4 or magnet 5 in the same plane as magnet 6. The stable positions of magnets 4 and 5 are governed by the north and south magnetic pole configurations provided in each magnet, as shown. One or more magnets such as 4 and 5 can be fitted to the shaft 2 to be rotated. Preferably, one shaft magnet 4 or 5, etc., for each stable shaft position angle desired would be used.

Fig. 1 illustrates the configuration where two stable shaft angle positions are derived. The relative thicknesses of the ring and shaft magnets 6, 4, and 5 respectively, combined with the separation distance between the shaft magnets 4 and 5, governs the type of angular rotation experienced by the shaft in response to axial motion of ring magnet 6. For many applications, it is desirable to obtain snap-action angular rotations as illustrated in Figs. 2A through 2D. A useful tactile property is experienced by the ring magnet 6, in response to sudden angular motion of shaft member 2 when magnet 6 is moved axially along housing 1, and conversely if ring magnet 6 is fixed in position and the housing 1 is moved axially through magnet 6. Figs. 2A-2D illustrate the angular attitude of shaft 2 as an...