US1648169A - Electric iron - Google Patents

Description

Nov. s, 1927. l 1,648,169

F A. FAHRENWALD ELECTRIC IRON FraK r\ Falwenwcnd BY I ATTORNEY.

Nov. 8, 1927. 1,648,169'

y F. A. FAHRENWALD ELECTRIC IRON Filed Feb. e, 1922 2 sheets-sheet 2 INVENTOR.

f1 BY HFhrerfd Patented Nm). 8, 1927.

UNITED" STATES i-.xrlazNTv OFFICE.

Aii'iauwx A. FAHRENWLLD, or cLEvELANnrmIen'rs, omo.A

ELECTRIC IRON.

This invention relates to electric laundry irons and has for its objects the provision of a new, improved, and simplified device of this nature which shall be more cheaply and 6 easily constructed more economical in current; less liable to burn out and more easily repaired in case of a burn-outthan other devices. Another object of my -invention is the provision in connection with such an iron of a heating element made of a material having physical E and chemical properties not heretofore united in any known substance and co-operating with the peculiar design of through a complete iron containing my im-A provements; Fig. 2 is a topk plan viewof the base of the iron; Fig. 3 is a, bottom plan view of the insulating plate 'together with the resistance member; Figs. 4, 5, and 6 are views similar to Fig.l 3 but showing diiferent designs of winding, and Figs.l 7, 8, 9, 10, `and 11, are detail views illustrating different modes of aiixing the-resistance element to its supporting member. y

DescribingI by reference characters the parts shown in the drawings 1 represents the 'base of an iron which is made in the Y usual or any desired shape, of cast iron or other suitable alloy, its top being recessed as shown at 2 and the bottom of the recess preferably being formed with suitable ribs 3 arranged according to any desired pattern,

l in order to increase the heat absorbing surface. To this base I-secure in any suitable manner, as by the screw 4, a top vcomprising a sheet-metal shell 5 shaped to fit snugly upon the base and having therein an insulating block 6 which depends into the recess 2a suitable distance. The shell 5 is preferably lined with some insulating substance 7 Isuch as asbestos, and I have further shown a space 8 iilled with some substance as min- 5 eral wool at the upper side of the block 6, the better t0 retain the heat Where needed..

Application med February 6,1922. serial nojsvaaau.

A Suitable handle eis attached to the shell 5 I by arms 10-10.in the usual or any suitable manner. Y

Secured to the lower face of the block 6 and projecting into close radiating relation l with the base is a resistance element 12, preferably made in the formof a small helical 4coil of suitable wire, wound in any suitable,

or desired pattern to afford a uniform distribution of heatV while at? the same time affording sufficient length to produce the necessary resistance."` Four different patterns or designs are shown in Figs. 3, 4, 5 and 6, and many others can be devised. The terminals are attached in any desire way, one ofthe best being. as shown in Fig. 1 wherein each end of the coil is attached to a bolt 13 of highly conducting material such as brass, whose upper end is secured by the flexible lead 14 with a stud 15 fastened to the shell 5 by the insulated nuts 16 .in such fashlon as to receive the removable cord-terminal 17. TheV wire coil is held in place in any suitable manner, one mode being to loop itV back and forth around the headed studs 2O carried by the insulating block, these studs being either integral as shown in Figs. 7

and. 8- or separable as shown in Fig. 9. In`

the last named case the bodytb of the block is formed with suitably locatedapertures 21 merging with counterfbores 22 at'the upper surface,the apertures receiving the Shanks 23 of the blocks 20b which are held in place by suitable cement 24 introduced into the counter-bores and interlocking with the grooves 25. `Another modev nfl-securing the resistance element is shown in Figs. 10 and 11 wherein the block 6b'is similarly formed with apertures 21 receiving the shanks of suitable staples 26 which embrace the coil y12, `the legs of the staples being outturned as shown at 27 and subsequently covered by an lnsulating layer 28. The body of the block is preferably formed with a depending Hange 3() which fits inside the recess and tends to shield the Walls from becoming overheated while directing theheat more vparticularly against the bottom of thev recess. The thickness of the ,bottom must be so chosen as to enable the iron to be quickly heated Without at the same time becoming ltoo uickly cooled and also to effect an even distribution of the heat, notwithstanding the vnecessary Spacing of the convolutions of the resistance elemert, The essence of my inventlon consists 1n,

lll() substance isfalmost unknown since most sublstances which are good conductors of heat are also rgood conductors of electricity, and the poor conductors of electricity are generally oor conductors of heat.V In addition practlcally all the substances possessing the .combined properties desired have a very brittle nature and possess a co-eflicient of 4expansion which is far different from both the resistance element and from the iron base. Accordingly an element so constructed is very brittle subject to mechanical breakage, deteriorates rapidly upon repeated heating and cooling and generally gives rise to hot spots, which cause an early burning put of the element. However it is easy to lnd a substance which has both electrically-insu-v lating, heat-insulating, and heat-reflecting properties, and any such substance will serve for the coil support in my improved iron. I

prefer a good grade of porcelain owing to the fact that it possesses the necessary mecha-nicaFstrength, electric resistance, and'percent e of reflection. By reason of the fact that 1t overlies the coil 1ts high heat-resistance becomes an advantage instead of a dis.-

advantage in coniining the heat eect to the bottom-of the iron where it is needed.l

However it is well known that the transfer of heat by radiation varies with a higher ower of the absolute temperature where-4 ore the iron works best when the element is maintained at a white heat, and owing to its exposure to the atmosphere and its suspension from above at spaced points, no substance has heretofore been known which was capable of producing such an element; owing `to the fact that it must both withstand atmosphericV oxidation and deformation dueto sagging. Such a substance has been discovlered b me in the form of certain alloys of `ehromlum with iron, and one or more additional metals adjacent to iron in the periodic table of elements. The alloy used contains at least about 70 percent of iron, with about It has longy 20 percent of chromium, and a small proportion, say one to 3 percent of either or both of the materia-ls manganese or 4titanium (or carbon and silicon being present as impurities to an amount of not above .5 percent each and preferably below labout .4 percent each. Wires of this alloy' drawn approximately to 28 gauge can be wound on a coil of pencil size supported as herein shown, and heated to incandescence for many hundreds of hours withoutexhibiting any observable sagging between their points of attachment. For the best effect it is desirable that the wires be shielded from below to the smallest possible extent thus :ermitting the maximum Aof radiation with the minimum number of supports.

I-t will be understood however that I do not limit myself to any details except as recited in the annexed claims.

Having thus described my invention what I claim is:

1. An electric iron comprising: a metallic base having a marginal upstanding flange.

defining a recess, upstanding ribs carried by the bottom of said recess, a; cover portion havlng a flange fitting outside saidlupstanding flange, a lining of heat insulating material'disposed in said cover portion, a block of non-conducting material disposed inwardly of said linin an unconfned resistance element carrie Aby said block spaced from but in radiating relation with the bottom' of said recess, and'means for securing together said base and said cover.

2. An electric iron comprising: a metallic base having a marginal upstanding flange defining a recess, upstanding ribs carried by the bottom of said recess, a heat insulated v cover portion carrying a block of non-conducting material having'l a groove therein,

an unconfined4 resistance ement supported FRANK A.. FAHRENWALD.

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