Browse Prior Art Database

Brushless Tachometer System

IP.com Disclosure Number: IPCOM000079350D
Original Publication Date: 1973-Jun-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 41K

Publishing Venue

IBM

Related People

Kripl, JF: AUTHOR

Abstract

Fig. 1 is a front view of a tachometer essentially showing the electrical parts of the system. Fig. 2 is an axial cross section essentially showing the mechanical parts of the system.

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Brushless Tachometer System

Fig. 1 is a front view of a tachometer essentially showing the electrical parts of the system. Fig. 2 is an axial cross section essentially showing the mechanical parts of the system.

The tachometer structure includes frame 1 containing bearings 2 which support shaft 3. Shaft 3 is driven by the device which is to have its motion velocity and direction indicated by the tachometer. Shaft 3 supports a nonmagnetic conductive coupling 4 which may be an aluminum disk.

Frame 1 also includes four extensions which supports ferrite cores 5a, 5b, 6a and 6b, respectively. Input coils 7a, 7b are mounted on ferrite cores 5a, 5b, respectively, which extend on one side of disk 4, and output coils 8a, 8b are mounted on coils 6a, 6b, respectively, which extend on the other side of disk 4.

Disk 4 passes through air gaps in the ferrite cores to couple induced currents from coils 7a, 7b, to coils 8a, 8b when shaft 3 is rotating.

Oscillator 9 drives input coils 7a, 7b with a high-frequency current in the range of 20kHz to 100 kHz, which generates magnetic fields in the circuitry of disk 4, whose relative directions are as indicated by the dot and the X in Fig. 1,
i.e., in opposition of phase.

When disc 4 is rotating, the electric currents induced by those magnetic fields in the disc induce magnetic fields in output coils 8a, 8b, which are in opposition of phase. The phase relation with respect to the primary magnetic fields and the magnitude depend upon the...