US1321682A - Zigzag carbon electric resister. - Google Patents

Description

J. THOMSON.

Patented Nov. 1l, 1919.

)TOEN THOMSON, or NEW YORK, N. Y.

-ZIGZAG CARBON ELECTRIC RESISTER.

Specication of Letters Patent.

Patented Novi 11, 1919.

Application inea october 7, 191s. serial No. 257,216.

To all 'whom it may concern:

Be it known that I, JOHN TiroMsoN, a. citizen of the United States, and a resident `of the borough of Manhattan, city of Newl York, county and State of New York, have invented certain new and useful Improvements in Zigzag Carbon Electric Resistere, of which the following is a speeilicatlon.

'l`he invention particularly relates to zig-zag, carbon, electric resistors for use 1n furnaces. Important objects of the invention are, to so form the resister and so dispose the alternating members which connect the zig-zags that a surtace, or surfaces, of the resister will bemaintained at a higher temperature than another surface, or surfaces; and to effect, in a. single carbon body of given lineal dimensions, a 'greater resistivity than has hitherto been realizable.

In the drawings,

Figure 1 shows a resister 1n plan;

Fig. 2 is a side elevation thereof;

Fig. 3 is an end elevation, as viewed from the bottom of Figs. l and 2;

Fig. t is a transverse section, as on the line A; and

Fig. 5 is a view similar to Fig. 4 but of modified design.-

The resister, B, is formed as from a carbon bar, whose, original cross-section would preferably be square, and two of its opposing sides are planed to angles C, D, forming a. wedge-like cross-section. The tapered side portions are then nearly entirely separated by forming a vertically land longitudinally extending central slot, E, passing from one end of the barI toward the other end, leaving thereat a relatively narrow portion, F; The zig-zags are p roduced by cutting alternating slits, H, which pass crosswise of the said central slot. The slits, H.-extend vertically and transversely. A, part of the. slits'll, extends downwardly from the top surlaee of the 'resister toward but short of the bottom surfaceof the resister leaving material, as at h', while the remainder of the slits Hextends upwardly from the bottom surface, toward but short of the. upper surface of the resister leaving material, as4 at h. In this wise each limb of the bar b 1, ,o||u-sa` distinct resister connected in series hy the end-section. or emmeetor, F. The resister, as a whole, thus simulates in its appearance the prongs of a tuning forli', each prong 4having a. similar number of '/.ig-zags. It may also be referred to as a U-shaped resister each leg of said U-shaped portion having a number of-zig-zags. Its separated ends ma be provided with copper terminals, as I, which are symbolically denoted 'as connected to a poner-circuit, K.

i The object of forming the angular sides is to produce a progressive increase of current density, and a corresponding intensity of temperature. Thus, which is best illustrated by Fig. 4, as"Y the electric current,

passes from the top, r, to theI bottom s, the cross-sectional area, due to the, taper, is ronstantly diminishing, where-by the lowersurface ofthe resister will be the. hotter. This condition can be advantageously availed of in-many cases, as by so setting or disposing the resister'that its hotter portion is presented toward the body to be heated. This effect has been previously realized by the present applicant, in the manner shown in his patent of August 8, 1916, No. 1,193,633, being therein paiticularly illustrated by Figs. 5, 6 and 7. In that case, however, the increase of current-density is obtained by causing the current to traverse the connecting portion of a zig-zag along lines of different lengths, the section traversed by the eurrent being uniform, Whilein the present ease the lines of current-traverse are of thesame length but the cross-sectional area progressively increases or decreases.

The. same densitying effect ican lbe attained in a resister which is not centrally separated, as is shown in F ig. 5, whose sideangles are sharper than in Fig-i. F or example, in this case the maximum increase of current-density, and the eorreslmmling heating efl'ect along its bottom surface, would be about 50 per centum greater than along its upper surface, with a progressive inerezise or decrease'throughout thc mass, as thecase. may be, from one surface to the other.

In the central slotted resister, as shown in the first four figures of the drawings, it is in fact a. member`having a compound cireuit formed from a monolithic bar or block, possessing the advantages of the utmost colnpzu-tn-ess, efliciency and endurance.

Obviously, where a wedge-like or other form (if eross-seetion whereby to produce a progressively increasing or decreasing current-density, would not be advantageous,

a carbon bar of square or rectangular secy tion may be centrally slottedand crosscuit, having a. restricted sectional area, with slated in the manner ,hei-ein" described, thereby realizmg'the advantage in singular of obtaining the utmost length of cirthe utmost compactness of structure.

What I. claim is:

1.' A zig-zag, carbon, 'electric resister having a longitudinal centrally disposed slot separating two contiguous series of zig-zags,

the said slot assing from one end of the l carbon bar or lock towardbut not entirely the other end thereof,

. zig-zag, carbon, electric resister, wedge-like in cross-section, in which the slits which produce the zg-zags pass crosswise of the wedge, whereby the area of the connecting portions progressively increases or decreasesv in the direction traversed by the current.

3. A monolithic, compound, zigzag, carbon, electric resister, formed by a a ,ranged slots that extend vertically and transversely of the resister member.

This sperilicution signed and witnessed this 21st day of August, 198.- i

JOHN THOMSON? Signed in the presence of- RALPH M. THOMSON, H. O. Wmo. y

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