Browse Prior Art Database

NOISE SUPPRESSION IN ELECTRIC MOTORS

IP.com Disclosure Number: IPCOM000026464D
Original Publication Date: 1992-Apr-30
Included in the Prior Art Database: 2004-Apr-05
Document File: 2 page(s) / 69K

Publishing Venue

Xerox Disclosure Journal

Abstract

Mechanical motion in machines is typically achieved through the use of electric motors. In some instances, the speed of the motors is also electronically controlled, for example, DC servomotors and stepper motors. When used in office equipment environments, these motors can frequently be the source of acoustic vibration, giving rise to considerable noise.

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XEROX DISCLOSURE JOURNAL

NOISE SUPPRESSION IN

ELECTRIC MOTORS

Charles E. McPherson John A. Forrester

Proposed Classification
U.S. C1.181/296 Int. C1. FOlN, GOlK

Mechanical motion in machines is typically achieved through the use of electric motors. In some instances, the speed of the motors is also electronically controlled, for example, DC servomotors and stepper motors. When used in office equipment environments, these motors can frequently be the source of acoustic vibration, giving rise to considerable noise.

Accordingly, the present invention is directed towards reducing the amount of noise emanating from such equipment. The reduction in audible noise is achieved by introducing a sound transducer into the equipment housing from which the noise emanates, and generating inverse phase vibrational energy with the transducer. In general, the motor vibrations are canceled by the transducer vibrations, thereby resulting in a quieter machine. More specifically, the major harmonic characteristics of the motor and housing are compared to the electrical pulse train driving the motor to determine a relationship therebetween. Knowing the relationship, the transducer driving electronic circuit can be designed to produce an inverse waveform that best cancels the effects of the motor vibration. In this feedforward cancellation scheme, the inverse waveform would then be conditioned electronically and fed into the sound transducer. Finally, the transducer would be positioned...