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Shaft Speed Detector

IP.com Disclosure Number: IPCOM000092084D
Original Publication Date: 1968-Aug-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 27K

Publishing Venue

IBM

Related People

Cuzner, DE: AUTHOR [+3]

Abstract

Reed switch 1 closes when shaft 2 reaches a predetermined speed of rotation. Reed switch 1 is mounted in soft iron circuit 3 having pole pieces 4 and 5 positioned one on each side of aluminum disk 6 which rotates with shaft 2. U-shaped permanent magnets 7 and 8 are similarly located with respect to disk 6 on either side of circuit 3. The polarities of magnets 7 and 8 are arranged such that a neutral zone exists between them in the region of circuit 3. Rotation of shaft 1 generates eddy currents in disk 6 as it passes between magnets 7 and 8 which shifts the neutral zone. Reed switch 1 closes when the magnetic field between magnets 6 and 8 reaches a predetermined magnitude which in turn is directly dependent on the speed of rotation of shaft 2.

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Shaft Speed Detector

Reed switch 1 closes when shaft 2 reaches a predetermined speed of rotation. Reed switch 1 is mounted in soft iron circuit 3 having pole pieces 4 and 5 positioned one on each side of aluminum disk 6 which rotates with shaft 2. U- shaped permanent magnets 7 and 8 are similarly located with respect to disk 6 on either side of circuit 3. The polarities of magnets 7 and 8 are arranged such that a neutral zone exists between them in the region of circuit 3. Rotation of shaft 1 generates eddy currents in disk 6 as it passes between magnets 7 and 8 which shifts the neutral zone. Reed switch 1 closes when the magnetic field between magnets 6 and 8 reaches a predetermined magnitude which in turn is directly dependent on the speed of rotation of shaft 2.

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