Browse Prior Art Database

Laminated Linear Voice Coil Actuator

IP.com Disclosure Number: IPCOM000076300D
Original Publication Date: 1972-Feb-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 51K

Publishing Venue

IBM

Related People

Dost, MH: AUTHOR [+2]

Abstract

Use of solid iron permits eddy currents to flow internally in such a manner that flux changes are counteracted, causing heat to be generated unnecessarily (i.e., requiring extra cooling capacity), and demanding more electrical power than necessary to counteract inductive effects due to eddy currents. For these reasons, rotating machinery is always constructed with laminated iron and high-power efficiency is typically attained.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 53% of the total text.

Page 1 of 3

Laminated Linear Voice Coil Actuator

Use of solid iron permits eddy currents to flow internally in such a manner that flux changes are counteracted, causing heat to be generated unnecessarily
(i.e., requiring extra cooling capacity), and demanding more electrical power than necessary to counteract inductive effects due to eddy currents. For these reasons, rotating machinery is always constructed with laminated iron and high- power efficiency is typically attained.

Lamination of linear actuators in the direction of magnetic flux is quite impractical for actuators with cylindrical gaps, but not for straight gaps. This necessitates coils with straight sides which can be produced almost as easily as round ones. Figs. 1a and 1b show the basic configurations possible with laminated iron paths.

Depending on the application, the open ended design (1a) or the closed circuit design (1b) may be preferable. The first has the advantage of easier coil access, the second features reduced stray magnetic field outside the motor envelope.

In both cases, the flux in the return path encounters no unnecessary gaps as between plates and rings in the cylindrical designs. Instead of the permanent magnets, shown with their directions of magnetization indicated by arrows, electromagnets are possible which may cost less and produce greater field strength in the gap. They could be produced by energizing stationary coils around extensions of the lamination stacks in lieu of the permanent magnets.

Note that the stampings for actuators with permanent magnets would have an E shape as shown in standard lamination catalogs, offered in many sizes and thicknesses by various suppliers. Also, note that mounting holes are located in places of low-flux density, causin...