US250175A - Elihu thomson - Google Patents

Description

(No Model.) v

E. THOMPSON.

ELECTED MAGNETIG DBVIGEQ No. 250,175. Patented Nov. 29.13%.

UNITED S'rAT s PA ENT FFICE.

nurse 'rnonson, on NEW entrain, connncrrcutr, ASSIGNOR To run AMERICAN ELECTRIC COMPANY, OF SAME PLAcE- E scTRo-M'AeNET -o Device.

srscrrrcn'rroiv forming part of see Patent No. 250,175, dated November 29,1881.

Application flied February 9,1881. (No model.)

To all whom it may concern.- Beit kno'wn'that I, ELIHU Tnon'rsoiv, a citizen of the United States, rosidin g at New Britain, county of Hartford,"'State of Connecticut, have invented a new and useful Electro-Magnet-ic Device, of which the following is a specitlcation'.

- The object of my invention is to obtain a greatly-increased attractive energy in electro. magnetic 'coils with movable cores, and also to construct a coil which when traversed by an electric current shall exert an axial attraction upon amovable core partially inclosed thereby, which attraction shall be practically constantjor a constant current, independently of changes of position within certain limits.

I apply my invention to all cases where great attractive energy is to be exerted through a considerable range of position of the moving core, and where the tendency olfa, core to enters coil is required to be the samcin various positions when a constant current circulates.

My invention is adapted to operate regulators for electric currents, electric-lamp mechanism, signal apparatus, &c.

Briefly, my invention consists .of a coil-of insulated conductor, through whichan electric current can be sent, surrounded by an iron casing'and inclosing a. movable core, having certain relations to a conical extension ofiron, ssherein described.

Figure 1 is a side view of the device, where Q is a helix or coilof wire; I I, a lateral outer 'cusin g of iron P, an iron base-plate, and conical extension'l- H, a movable. iron tube or hollow eore. Fig. 2 is in all respects similar to Fig. 1, except that the parts are inverted.

Referring to Fig. 1, 0 is a coil through n hich a current of electricity is passed, which causes an axial attraction of the core, H, of iron, into the-interior of said coil; but this attractive force is very feeble when coil and core only are used.

My improvement consists in adding an external iron casingextendin from the top of the coil 0 over its sides an tothe iron. plate P. I am thus enabled to obtain from; a 'given core from four to five times the mechanical energy in entering'the coil 0 as would be obtained without the casing; but to further base-plate P.

improve my device and enable it to be readily adapted to its various uses, 1 procure an attractive energy constant for the some current strength, notwithstanding chan geso'f position 'of the core H with respect to the coil 0, by the introduction of an' iron extension, P, extending upward-in the center of the coil from the A central rod is attached to the. core H, by means of which its force may be transmitted. A weight, W, issoinetimes used to counterbaiancc,either'partly or entirely,

the weight of the core H. Ahrass tube, J,

surrounds the movable core H, and it is preferably filled with oil or glyccrine, in order to damp or check sudden motions of the core.

The casing need not cover the coil-(loompletely, but may consist otany mashrbf mag. netic substance serving to join and convey. the" magnetic polarization around the exterior of the coil O, and from end to end cxteriorly.

Fig. 2 shows the parts inverted, and this is sometimes a convenientdisposition.

The object of the cone P is to compensate for the diminished axial force of the coil 0 It is well known that when a plain iron-core is attracted into a helix the magnetic efi'ect rises to a maximum, then falls to a minimum or zero, when the center of the coil is in the same position as the center of the core, and various devices have been attempted to overcome this changing force and render it.more uniform. The coil itself has been wound tapering, the core has had various outlines given to it, counterbalancing devices I used to increaseand diminish their effect upon the core, and thus obtain uniformity of action in various positions;

but I do not find that by any other device than my present invention, or its manifest equivalent, powerful attractive energy and uniform attraction in'various positions have been rea'b ized, and I attribute my results to the casing or closed magnetic circuit outside the coil opcr sting in-conjunetion with the'annular core ,H and conical extension P. The motion of the core H toward the base of the cone P brings the sides of the cone or taper P! nearer the core H, and there results an increased attractive force, which is greater as'the direct'axial force of the coil 0 upon the core H is less, and

by properly shaping the parts, the variations of the one being opposite to those of the other, a uniform tendency of the core H to move within its coil 0 axially is produeed with the same current.

With various dimensions of parts experiment will determine the proper proportions to be enrployed to obtain all the effects desired;

bit for the guidance of those skilled in the art a single example will be given. I have made the coil live inches in length, five inches cxternal diameter, three inches internal diameter; the core H five inches long, two and three-fourths extt -nal diameter, and two and one-fourth internal diameter; the cone 1 two and three-fourths inches high, two inches wide at base, and tapering upward nearly to a point. With a casing about one-fourth inch thick an attractive forceis obtained practica'llyunit'orm for arange of one and one-fourth inch movement of the core when a constant current is flowing through the coil. An equivalent arrangement isto provide the core H with atapering conical extension and cut a circular opening in the base-plate I, through which the taper extremity of the core may pass as said core is drawn into the coil 0. It is thus that the iron of the core gradnall y gains proximity to the base-plate and uniformity of action is obtained.

I claim as my invention---' 1. In combination with a hollow movable core placed in the interior of a coil of wire or helix, an external casing and tapering exten' sion connected to said casing for the purpose of'obtaining an axial attraetiveforce constant foraconstantourrent,independentlyof changes of position of said core with respectto said coil within practicable-limits.

2. A movable core, H, surrounded by a coil of insulated wire and immersed in avessel ofoil or glycerine, and whereby said core is checked in its movement, in consequence of the resistance to the passage of said oil or glycerine from a position above said core to a position below it, and vice versa.

3. The combination, in an improved electro' magnetic device, of the following elements, viz: a coil or helix, a. movable core, a vessel of oil or glycerine in which said core moves, an exterior iron casing, and tapering extension of the same interior to said coil or helix.

ELIHU THOMSON. Witnesses:

E. W. RICE, E. F. PECK.

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