Browse Prior Art Database

Electromagnetic Devices

IP.com Disclosure Number: IPCOM000076028D
Original Publication Date: 1971-Dec-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 3 page(s) / 56K

Publishing Venue

IBM

Related People

Malmros, GV: AUTHOR

Abstract

Electromagnetic actuators such as relays, solenoids, print magnet hammers, etc. are characterized by the use of two elements in the actuator system: 1) A magnetic path closure system. 2) A spring return element.

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Electromagnetic Devices

Electromagnetic actuators such as relays, solenoids, print magnet hammers, etc. are characterized by the use of two elements in the actuator system: 1) A magnetic path closure system. 2) A spring return element.

These are separate elements, since the purpose and characteristics of the two differ. The magnetic path closure system element (the actuator or armature) is usually of a high-permeability material requiring adequate magnetic cross- section to carry the necessary magnetic fields, and generally is of a soft ferrous material--not hardened. The spring return element is usually of spring steel, hardened, and has poorer magnetic qualities, having appreciable residual magnetic properties and higher coercive force strength. The cross-section is usually much smaller than that of the armature, in order to provide the generally needed spring characteristics.

In combining these two elements to make an electromagnetic actuator, two air gaps usually result: 1) The working air gap, across which the actuator travels

to perform its work motion.

2) The sliding or minor air gap necessary to complete the

magnetic path between the main or static magnetic structure

and the armature or moving element.

Thus, two air gaps result, one of which does not contribute to the efficiency of the total magnetic system. In fact, the second, or minor air gap is usually a sliding gap, wherein friction and wear result.

Described is a technique which eliminates the second or sliding air gap by changing the method of construction of the armature or moving magnetic element. Instead of the armature being made in one solid piece, it is made up of laminations of magnetic material, whereby the equivalent required magnetic cross-section of the solid armature element is obtained by the several laminations. These magnetic laminations are separated from each other in terms of the magnetic material itself, but may be coated with a low-friction surface. The laminations may be bonded together with a thin layer of elastomeric material, etc. The laminations may, in fact, be so arranged that they do not touch each other. A number of different arrangements may be considered, which will allow the optimum of slippage of one lamina with respect to another.

To provide another form of damping, the laminae may be made up of different thicknesses, some thinner or thicker than others, in order to minimize ringing or vibration. What is accomplished by this arrangement is that the necessary magnetic cross-section is provided, yet the flexibility of this cross- section is such that it will provide...