US1143574A - Electric resistance element. - Google Patents

Description

H. W. DENHARD.

ELECTRIC RESISTANCE ELEMENT.1

APPLICATION FILED OCT. 31.1911.

Patented June 15, 1915.

UNITED STATES PATENT OFFICE.

HARRY W. DENHARD, OF SAN FRANCISCO, CALIFORNIA, ASSIGNOR TO THE CUTLER- HAMMER MFG. (30., OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN.

ELECTRIC RESISTANCE ELEMENT.

To all whom it may concern:

Be it known that I, HARRY IV. DENHABD,

a citizen of the United States, residing at San Francisco, in the county of San Francisco and State of California, have invented new and useful Improvements in Electric Resistance Elements, of which the following is a full, clear, concise, and exact description, referene being had to the accompanying drawing, forming a part of this specification.

My invention relates to electric resistance elements.

It is especially adapted for use in connection with electric heating devices, such as electric laundry irons, and it is in this connection that I shall describe the same in this application. My invention is not however, limited in its use to this specific adaptation.

My invention has among its objects to provide an improved electric resistance element which may be manufactured at very small expense and assembled in a very compact form, so that the heat generatedby the same is distributed in proper proportion to the object to be heated.

A further object of my invention is to provide an improved electric resistance element adapted to use in connection with an electric iron, which is formed of aplurality of strips of resistance material which are so made as to permit them to be assembled in the. form of a unit which conforms to the shape of an iron and which distributes the heat generated in the desired proportion tp the "arious parts of the iron.

Other objects and advantages of my improved construction will hereinafter appear.

In the accompanying drawings I have illustrated one form which my invention may assume in practice. My invention is not however, limited to this specific form.

In the view of these drawings :Figure 1 shows av plan view of a blank from which the resistance element is formed. Fig. 2 shows a plan view of an assembled unit. Fig. 3 shows a sectional view of the unit in position in an iron.

In the construction shown in the drawings, a blank 1, of a resistance material, preforabiy metallic, is made up in the form of a strip and punched as illustrated in Fig. 1. This blank-is preferably slotted throughout the greater part of its length as at 2, (Fig.

Specification of Letters Patent.

Application filed October 31, 1911.

Patented June 15, 1915.

Serial No. 657,802.

1) in the well known manner and. one side of the same is tapered toward a point near the middle 3, which when the blank is bent into the shape of a unit, forms the tipof the same. In order that the heat may be greater at the tip of the iron, due to the fact that the heat is more readily dissipated at the tip, I so arrange the unit that a greater heat developing surface is present at the tip. This I do by bending the blank along a horizontal line at the point 3, until the two halves of'the same lie in horizontal planes. Since it is unnecessary to heat the back 'of the iron, to the high temperature required at the tip, I preferably leave one end of the blank unslotted, as shown at thedower part of Fig. 1.. In order to enable the unit to be held in position in the iron, I preferably provide suitable perforations 4, which when the unit is assembled, are arranged concentrically. In order to enable suitable electric connections to be made, I provide each of the blanks with an extension 5, at one of its ends, which is preferably stamped out with the blank, and I also preferably provide a perforation 6, at the opposite end, so that the terminals may be connected to the unit as by riveting if desired.

When the unit is assembled it assumes the form shown in Fig. 2, wherein the two halves of the blank shown in Fi g. 1 are folded upon each other along the line 3, so that when the two halves are placed together with their straight edges in parallel relation, a unit is formed which will conform to the shape of an iron, in which it is desired to place the same. When in this position, the lower flap of the blank shown in Fig. 1 rests upon the flap shown at the top, and the perforations 4, register with each other, while the perforations 6 are brought close together at the back of the iron. The extensions 5, at the back of the units. are connected together in any suitable manner as by crimping or if desired, by brazing or welding, so that a complete unitary structure is provided. In order to insulate the parts, the two flaps which are bent over upon each other mayv be suitably spaced from each other by a sheet of insulation 7. If desired I may use mica as this insulation.

In 3, I have shown one manner in which the unit may be placed in position in an. iron. For purposes of illustration, the

, I-employ mica as this insulation. When placed between these sheets K of insulation the unit is then placed between the storage plate 9, and the body portion 10,- of the iron,

' as shown' in Fig.- 3. As usual in such constructions, the plate 9 may be brought down .very tightly upon the unit by means of suitable screws, or bolts 11 so that the unit is clamped between the surface of the plate and the body portion of the iron. Since this form of clamping. the unit within the-iron is well known, I have not illustrated the same in detail in the drawing.

By my improved construction, I am able to produce a unit whichmay be made up into very thin form, so that it may be brought into intimate relationwith the sur face to be heated, and thus reduce the amount of heat lost through radiation or otherwise. Further, by the use of the slotted resistance material, I am able to provide a unit of high heating capacity. By my improved means .of arranging the unit, I am able to distribute the heat to the parts of the iron where it ismost needed, and in the desired proportion, so that a practically uni form temperature may be. maintained. Further, I am ableto-providean ellicient unit .of high heat developing capacity which may be' manufactured very cheaply and be readily placed in'position.

While I have, in this application, described one form which my invention may assume in practice, my invention may assume other forms than that shown, and I accordingly wish to cover within the scope of this application all of these forms of my invention falling within its spirit.

hat I'claim as new and desire to secure by Letters Patent isz 1. An electric resistancev unit formed of a pair of strips of slotted resistance ribbon each bent back. on itself to form parallel portions, said portions being of similar shape and conforming to the outline of the object to be heated, the lower portion having slots throughout its length and the upper portion having slots for a portion of its length whereby the maximum quantity .of heat is developed at one end of the unit, the

. adapted to each bent back .onitself to form parallel portions, insulating means between the portions, said portions being of similar-shape and of an area substantially equal to half the area of the base of the iron, the lower portions of each strip being connected to gather electrically at their free-ends and.

slotted throughout their l'en -th, the upper portions of cach'strip beings otted near the bent-ovcr .end whereby the maximum quantity of heat is generated atone endjof the un t, the free end of the upper portionsof the strips being adapted to be connected to electric terminals.

- -3. An electriehoating unit having a pair strips of slottcd'resistance ribbon adapted to conform .to the outline of the object to be heated and each having an area substan tially equal to the areaof one-half of the base of said object, each of saidstrips havmg a terminal portion which is bentback on the strip and insulated therefrom, said ter-- minal portions. being slotted adjacent theirbcnt-orer ends whereby the unit has amaX1-' mum heat developing capacity near one-end,

the free ends of said terminal portions being be connected ito an electr1ccir-- cuit. 4; An electric resistance unit formed of a single length. ofslotted-T- resistance J ribbon.

having a body portion and a partiallyslot- 'tcd terminal. portion-bent over-upon one surface of the'body portion andinsulated therefrom, whereby the unit has a maximum heat developing capacity near one end,

the-outline of said terminal portionbeing shaped to coincide with the outline of said body portion and both conforming to the shape of thesurface to .be heated.

5. An electric. resistance unit formed of a single length of slottedresistance ribbon having one'edge of the same tapered toward the center of the strip,said strip being tolded substantially at its middle line to form two layers, the end ofone of said layers being left unslotted. 1

In witness whereof, I have-hereunto subscribed my name in the presence of two witnesses. Y J e HARRY WFDENHARD. Witnesses: 7

F. L. ROCKWELL, Geo. B. Jones.

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