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Method for Aligning Electromechanical Device in Magnetic Field

IP.com Disclosure Number: IPCOM000127671D
Publication Date: 2005-Sep-08
Document File: 3 page(s) / 126K

Publishing Venue

The IP.com Prior Art Database

Related People

Gregory L. Bradley: ATTORNEY

Abstract

A method for reducing the effects of external magnetic fields on the operation of electromechanical devices utilizing magnetic fields or ferromagnetic materials for their operation, and vice-versa.

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Technical Publication No. 05-002

Method for Aligning Electromechanical
Device in Magnetic Field



James A. Patterson, Bradley J. Adams, Chris L. Swenglish, Edward P. Liscio

A method for reducing the effects of external magnetic fields on the operation of electromechanical devices utilizing magnetic fields or ferromagnetic materials for their operation, and vice-versa.

SPECIFICATION

This method permits the electromechanical device to align itself with an external magnetic field in a preferred orientation such that the external magnetic field interference on the device (and vice-versa) is minimized. In this particular implementation, the device allows an electric motor to align itself such that the drive shaft centerline is parallel with the field lines of the external magnetic field.
Electric motors rely on an internal magnetic field to generate torque to turn the motor shaft. In the presence of a strong external magnetic field the available torque at a given input motor current level is decreased. This decrease is due primarily to the additive effects of the external field on the internal fields of the device. Depending on the orientation of the device relative to the external fields, the internal magnetic fields may be reduced or increased such that the net torque available deceases. Operationally, this is generally overcome by supplying higher levels of drive current to the motor in order to overcome the losses.
In the case of the electric motor, aligning the motor such that the internal fields are perpendicular to the field lines of the the external magnetic field results in reduced interference between the external and internal fields. In a particular case of a DC motor, this preferred orientation is such that the motor shaft is parallel to the external field lines.

The primary implementation of the device places the electric motor in a gimballed or gyroscope-style mount that allows rotational freedom of motion about three axes, i.e. the motor is free to pitch, roll, and yaw about its center point. The natural magnetic torque force of the external magnetic field on the electromechanical device causes the device to align with the field. In cases where the torque force on the device itself is insufficient to do so, a small amount of ferromagnetic material may be added to the device at a distance from the center of the device along the preferred axis of orientation to increase the effects of the external magnetic torque effect to allow alignment.
Variations to this device limit range of motion on one or more axes based on assumptions about the orientation of the external magnetic field and the orientation of the device.
An additional implementation of the device places the motor on the end of a flexible rod such as a spring, which allows limited freedom of motion about...