US350957A - Electro-magnet - Google Patents

Description

I (No Model.)

B. THOMSON.

ELEOTRO MAGNET.

No 350,957. Patented Oct. 19, 1886.

WITNESSES: 1 IIVVEIVTOI? W:: /5@/w BY A 770mm N. PETER3. Pholc-lilhcgnpher. washm wn. D. c.

UNITED STATES PATENT Grricn.

EL'IHU THOMSON, OF LYNN, MASSACHUSETTS.

ELECTRO-MAGNET.

SEOIFICATION forming part of Letters Patent No. 350,957, dated October 19, 1886.

Serial No. 190,405. (X0 model.)

To ctZZ whom it may concern:

Be it known that I, ELIHU THOMSON, a citi zen of the United States, and a resident of Lynn, in the county of Essex and State of Massachusetts, have invented certain. new and useful Improvements in Electro-Magnets, of which the following is a specification.

Myinvention relates to electro-magncts; and its objects are, first, to secure by a very simple construction a practically uniform attraction in the various positions of the parts for any given magnetic excitation.

A further object of myinvention is to cause the parts to move step by step, or in such way that equilibrium shall be attained at certain definite points only in the range of movement of the parts, and at any intermediate point the want of equilibrium shall cause the parts to move in one direction or the other to one of their definite positions.

The latter part of my invention is especially applicable to the kinds of magnet in which the two polar or magnetic portions do not move directly toward one another-as, for instance in a line perpendicular to the pole-face of the magnet-corcas is the case with an ordinary electro-magnet, but at an angle to one anotherthat is to say, in such way that the line of movement of one part prolonged would cut the plane surface of the other extended or not. The class of magnets to which I here specially refer might be also defined as onein which the movement of bodily translation of one or the other of the two polar or attracting portions, either backward or forward, under variations of magnetic influence, is always greater for any given movement of translation than is the extent of approach or recession of the polar or attracting surfaces.

In the accompanying drawings, Figure 1 is a perspective view of an electro-magnet embodying my invention. Fig. 2 is aside elevation of the same with the magnet-coil removed. Fig. 3 shows in detail the two polar or attracting portions of the eleetro-magnet-to wit, the pole end of the magnet-core and the iron armature in the field of said pole end. Figs. at, 5, 6, 7, 8, 9, 10, and 11 illustrate in side view and front elevation various forms of my invention.

Referring to Fig. 1, C 0 indicate the coils of an electromagnet, ill M, of the ordinary form, and Y the usual iron yoke connecting the rear ends of the two cores or legs of the magnet.

A indicates the armature, which is mounted on two arms, 13 B, extending along the sides of the magnets, and pivoted 011 suitable bearings or pivots, P P, mounted on the yoke Y Y or adjacent thereto in about the positions shown. he armature, it will be evident, will move transversely to the magnetic axes of the magnetcorcs, and, with proper arrangement of the parts, will move by the pole ends. The magnet-pole M is cut away or formed at its lower portion or side in such way that when the armature is retracted or in the position shown the distance between the polar or attracting surfaces of the core and armature shall be at a maximum, while as the armature rises the distance shall decrease, as indicated by the dotted lines, the outline or curve of the pole-face being, however, such that its curve shall become more and more nearly (proceedthe path described by the armature. The outline or shape of the pole-face of the core (or of the armature, as will be presently seen) can be readily made such that a practically uniform pull or attraction exists throughout the range of motion of the armature, at the same time that the force of the attraction very considerable and the swing of the armature large. To secure this result it is only necessary that the curved surfaces of the pole and armature presented to each other shall c011- tinue to approach but never touch, and at the same time that the direction of the lines of contour of the pole shall approach more and more nearly to parallelism with the curve of the swing of the armature. This is indicated in alarger way in Fig. 3. It is not necessary that the armature A be a round bar, as it can be shaped in many other ways, one of which is indicated in Fig. l, where its nearest side presented to the magnet M is rounded, while its remote side is square.

For many purposes it is desirable that the magnet shall not only possess uniform or nearly uniform power throughout its range of 1 movement, but that it shall also move in such ing upwardly) parallel to the curve indicating range step by step. I secure this action by notching or grooving the face of the magnetpole or armature, when suitably arranged, so

that the magnet-faces opposed shall not present a continuous line, but shall have depressions and elevations, while the general contour of the faces is preserved. One of the ways of securing this is indicated in Fig. 5, where a number of small grooves, V V V, are cut across the face of the magnet, as shown. The grooves at that portion of the pole toward which the armature approaches very closely must be very small and shallow, while those at the portion where the armature is more distant can be quite large in comparison. If we now assume that a certain degree of energization exists in the magnet-pole M, the armature, being in equilibrium below the lower groove, should, if the parts are properly shaped, be capable of remaining in equilibrium between any two grooves or above the upper groove with the same energization or power of the pole M. It will not, however, remain in equilibrium opposite any one of the grooves, but will pass either above or below the same. I call this a step-by-step magnet because in exerting its attraction it imparts motion of a step-by-step character.

Fig. 7 shows a modification of the magnetpole and armature in which the face of the pole M is itself rounded and the shape of the opposing face of the armature is made such that in the latters passage over the pole by a swing in an are, as before, the lower portions of the armature come gradually nearer and nearer to the projecting surface of the magnet pole and give the same effects as in the arrangement shown in Figs. 3 and 4, except that the shape of the magnet-pole has now been conferred upon the armature and the shape of the armature has been conferred upon the magnetpole. The grooves for the step-by-step action can likewise be given to the armature, as seen in'Fig. 8.

As an illustration of the utility of astep-bystep magnet, I have shown it in Fig. 9 applied to adjusting a variable resistance, R, in which a series of contact-plates are traversed by a contact carried by the armature A. Now, it is oftentimes desirable that the contact-plate J should not rest on the break between any of the contact-plates of the variable resistance, as from such action uncertain contact may result and a burning of the plates or the traveling piece J may follow. If, now, the positions of equilibrium of the armature A before the magnet-pole M correspond to the positions at which the piece J is resting upon the contactplates, singly, it is evident that the magnet will serve to adjust the resistance R during the movement of its armature step by step, and will not permit the contact J to make uncertain contact with one or two plates.

It is obvious that by simply grooving the pole-face, as indicated in Figs. 5 and 6, the portions of the pole-face between said grooves constitute attracting projections systematically disposed so as to cause the armature to come to rest at certain definite positions in its range of movement, which positions depend upon the number and location of the attracting projections. In other words, the attract ing projections give an increased pull upon the armature in certain definite positions, while in those portions of the range of movement of said armature between said positions there is a lesser pull, &c., the result being that the armature cannot rest in the latter positions, but will be caused to take positions corresponding to the location of the attracting projections.

Instead of forming grooves in the pole-face, it is obvious that the same effect may be attained by forming upon the pole a series of very slight projecting studs or knobs, as indicated in Figs. 10 and 11, which of themselves are sufficient to cause the armature to hesitate or stop in its motion slightly at different points in its swing.

It will be evident that numerous changes in the configuration of the face of the magnet or its armature to secure the result described may be made, and that, so far asthe feature of step-by-step action of the magnet goes, it might be applied without change of principle to many existing forms of magnets giving a prolonged range of action.

What I claim as my invention is l. The combination, with an electro-magnet, of a reciprocating armature having a rounded face and moving transversely to the axes of the cores, a frame sustaining said armature and pivoted at or near the yoke of the magnet, the poles of the magnet being formed, as described, with a curve gradually approaching the line of swing of the armature and gradually becoming more nearly but not quite parallel thereto, as and for the purpose described.

2. A magnet-pole having a series of elevations or projections, arranged as described, for the purpose of'locating the position of the armature and securing a step-by-step action of the same.

3. The combination, with an electro-magnet whose attracting polar surfaces of core and armature approach to or recede from one another during movement to an extent less than the maximum movement of the translation of the parts, of a pole-surface having a series of attracting projections for giving a step-by-step movement to the armature, as and for the purpose described.

4.. In an electro-magnet having a substantially uniform pull upon its armature through its range of movement, an attracting-surface having systematically-formed attracting projections, arranged as described, to give a stepby-step movement of the parts, while at the same time serving to hold them in equilibrium in the various positions corresponding to the said elevations and depressions.

5. The combination, with an electro-magnet having its parts properly mounted to permit the core and armature to gradually approach, i as described, of a pole-surface having a series of attracting projections, as and for the purpose set forth.

6. The combination of an elcetro-niagnct having a curved polar face', an armature mounted so as to gradually approach said core, and a series of attracting projections systematically disposed on the attracting-surfaces of core or armature, as set forth.

'7. Thecon1l1 inatio11, with an electro-magnet, of a series of attracting projections systematically disposed, as described, and of progressively less magnitude, as and for the purpose described.

S. The combination, with an electro-magnet, of a series of attracting projections systematic ally disposed, as described, whereby the moving parts may be caused to move step by step or to assume certain definite positions through out the range of movement, depending upon the location of the several projections of the series.

Signed at Lynn, in the county of Essex and State of Massachusetts, this 27th day of Jan- 25 nary, A. D. 1886.

ELIHU THOMSON.

lvitnesses:

M. L. THOMSON, J XV. GIBBONEY.

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