US1333542A - Lifting-magnet - Google Patents

Description

" )STAInspra-TENT'- oFFicn :naar acmssmenn, or New vonk, n. Y.

Lrrrmnaanm. 1,333,542. Speculation el Lettmlatent. i Patented Mar. 9, 1920.

' 'I l Application llled .'Tuly l, 191B. Serial No.2'42,95. p To all 'inkom'. it may concern: polar extensions. in the ordinary 'forms of Be it known that I, Hannr G. Gnxsemonn, a citizen of the United States, residing at New, York, in4 thencounty of New York and State offNew York, have invented certain new and useful Improvements in Lifting- Magnets, of which t e following is a specication.

This invention relates to lifting or pulling magnets provided with an armature thle movement of which through a predlltermined air gap is utilized to perform work.

Everyelectro-magnet has two airgaps in the magnetic circuit and in the majority of cases,"r'e resented by the Vplunger type, only one of e gaps is utilized to exert a tractive e'ort but the other gap, due to its magnetic reluctance, absorbs ai certainproportion of. the energy of t'flemagnetizing`"coil.

The .bbject of my inventiofn is -toxprvide a construction. which greatly re uces the magnetic reluctance of the idle prior constructions and to secure t e greatest tractive ellortpwith the minimum expend itune-of electrical energynf 'j Y,

The tractive elifort exerted between "two poles or across a variabl gap,with the number of lines of force fer unit area. r'emaining the same, depends "upon the square of themagnetio force across the gap and the square-of the diameter of the gap. If the reluctance of the idleV gap is equal to that ofthe tractive gap, the magnetic force actin across the active" a would be represented` by 0.5, and the traciive eil'ort by 0.25 of the pull, which would beexerted if there ,were no idle gap, neglectin `of course the slight amount absorbed by t c reluctance of the iron of the magnetic circuit. This represents the best practice in magnetic structures. If the re uctance of the idle gap is reduced to one quarter o f'that of the active ga the magnetic force at the active fpole wiil be 0.8 and the tractive e'ort 0.64 o theoretical magnetic structure..

From lthe vfore oing facts re arding magnetic 4structures 1t is evident t at the tractive ell'ort is increased by increasing ythe diameter ofitlie pole or lines of force per unit area remaining the same. `@wing to mechanical diiculties of increasing the area of the polesby means of p :over

the

gap, the number of weight. These several advantageous features are of importance where small forces arc available.

Myrinvention will be understood from thc following detailed description in connection with the'aocompanying drawing, which rcpi rcscnts a longitudinal vertical sectional vicw of a lifting or traction magnet vembodying the features claimed.'

a Aminimum of space and permits the use of an amature of mlnlmum The manietic .structure4 comprises a, cylindrical she l or casing 2, having an aperture in its closed end intov which the core `3 is threaded or otherwise secured, the lower or polar end having an extension 3. The base 5,.also of magnetic material, is preferabl threaded to theouterannular rim of the sliiell and is rovided with an inwardly projecting cylin rical extension 6, which is cupped or hollowed out to form an annular lip or ring portion7 said cylindrical extension forming with the throat portion 2 of the shell, an annular air p -9. The arma,- ture 10 may be convenlently formed by drawing a disk of magnetic material into the shape of a shallow cup, the annular flange portion 10' extending gap 9, which constitutes the'idle gap of the ma ctic circuit. The armature may be attache to a boss 12, carried by an operating stem 14. The stem may be connected in any suitablemanner to a valve, switch, or any other mechanism to be actuated. It

into the annular a1r- :s shown as sliding through the core 3 and base member 5, but it is evident thatit may only slide within the'co're if desired, depending upon the duty of the magnet. In fact, this ma nctic structure can be readily made air tigt and the armature stem may act as the valve stem where the valve seat is made e. part of the magnetic structure. The energizing coil or winding '15 surrounds the core usual and may be supported upon the polar extension 3. The terminals o the'coil may be connected to binding posts or bolts 17,4 which pase through in-l sulating bushinps locatedin apertures in the wall of the shel It will be understood by those familiar with magnetic devices that the lines of force or magnetic tlux generated bv the current ilowing in the energizing coi 15, traverse the core, spread out through the gole piece 3', bridge the active ga 8, an thereby create a stress or pull w ich results in lifting the armature to the le. piece. The lines of force spread out ra ially in the armature,

assing into the annular llangel and then ]umping the double gap in opposite directions to the cylindrical base extension and the neck of the shell respectively, the lines completing the circuit through the shell to the core.

It is apparent that the degree of saturation of the armature is uniform throughout the diameter of the pole and only decreases to zero in the annular flange or liplO, and

hence the mass or weight of the armature is A ellectively used in carrying the ilux lines.

In 'actual constructionY the armature may readilyl be formed with the flange or li portion about equal in height bo one-thir of the diameter of the top or main body pottion, or to provide a flange area within the annular idle gap between the base and shell,

about equal to twice the area of the pctive polar gap between the top of the' rmature and th pole piece. The clearance between the annular lip of the armature andthe opposite walls of the annulargap can usually be reduced to one half the lengthi ofthe active polar gap: so that, as in the example taken above, the reluctance of the idle gap would be one quarter of that of the active gap, The oppositely acting stresses in the annular idle gap arobalanced and therefore neither add to nor subtract from the trartive eli'ort of the magnet. The

small stressin the gap between the top-edge 7 of the cylindrical lip of the base extension and the under side of 'the armature is so slight as to be practically negligible as will be -apparent from a consideration of the relation of parts. The distance between the magnetic reluctance ofthe several paths or' lip edge 7 and the armature is at least twice as great as the distance laterally or radially in the annular gap from the armature flange to the walls of the gap. ANow, the distribution of ux is inversely as the length of the gap. If the vertical gap distancebe twice the radialgap distance and the edge surface 7'* of the lip is one-eighth of the' armature surface extending within the annular gap, than the proportion of linxv lines between the lip edge and the lowerside l or lith of that of the active of the armature would be one-sixteenth of that passing through the annular gap or the active ga The pull o f the magnet is in proportion to the square of the lux lines area ol the gap As the area of the li edge gap is one-quarter of that of the wor ing gap, the dowpward,

or negative pull wouldbe equal to and changesv may be made" without-'depart ing from my invention; I claim 1.I A liftingor magnetic structure provided with-an active gap across which thetractive eort is exerted and an idle-gap, and 'an 'armature operative traction magnet having a within the active gap`and having Ian o'set44 portion extending within .the idle gap.v 's 2. A liftingor traction migmet 'havmgal rovded ,with anactive magnetic structure gap across which t atractiva eil'ort-isen erted and an annular idle gap` and an artig ture operative within the active gapjaiid having an 'annular oil'set lip portion orfiange proiecting into the idle php5.

B. A lifting ortraction magnetliaying Y magnetic structure provided 4with a. shell portion constituting-the return for the maig-- netic circuit` a pole piece extending inwardly `from the closed rinner volte end ofthe shell;i

and an armature operative in theamctivegap in front of the pole piece andiifli'aving an odset lip portion extending' adjacent the inner wall of the outer end ofthe shell, the

ins

space between said lip and said inner shell wall constituting an idle gap.

4'. A traction inagnethavim! structure provided with a 4shell portion. a core portion extendinginwardlv from the inner yoke end cnt .the' shell and having-iin enlarged pole niece. an' energizing winding 'sm-rounding'the core portion,a p' ber fitting within the outer end of the shell and having an inwardlvproiecting part ex 4tending adiacentthe inner shell wall. the

annular space therebetween constituting the a maimeti base themidle gap` and an armature operative'in front 1,sss,a42 8 of the pole piece and having a anged anand a cup-sha ed armature having the annular lip or skirt portion extending within nular side or iip portion extending Within said idle gap. l said annular space and the main body por- 10 5. A traction magnet of the shell type tion operative within the activegap. 5 having a closed magnetic circuit provided In testimony whereof I affix my signature.

"With" interior active and idle gaps, the laty ter being in the form of an annnlai` space, HARRY G. GEISSINGER.

Images