US1404063A - Electric heat-producing element and applications thereof to apparatus or articles - Google Patents

Description

E c. H. mums. ELECTRIC HEAT PRODUCING ELEMENT AND APPLICATIONS THEREOF T0 APPARATUS 0R ARTICLES. APPLICATION FILED JUNE 29,1920.

1,404,063. Patented Jan. 17, 1922.

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C. H. RODDIS. moms HEAT rnooucms ELEMENT AND APPLICATIONS THEREOF T0 APPARATUS 08 ARTICLES. APPLICATION FILED JUNE 2911920- 1,4()4,063, Patented Jan. 17, 1922.

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UNITED STATES;

garsur OFFICE.

CHARLES HENRY RODDIS, OF BEDFORD, ENGLAND. i

ELECTRIC HEAT-PRODUCING ELEMENT AND APPLICATIONS THEREOF TO APPARATUS OR ARTICLES.

Specification of Letters Patent.

Patented Jan. 17, 1922.

Application filed June 29, 1920, Serial No. 392,631.

To all whom it may concern:

Be it known that I, CHARLES Hnnnv Robins, subject of the King of Great Britain,

residing at 66 Elstow Road, Bedford, in the county of Bedfordshire, England, electrical engineer, have invented certain new and useful Improvements in Electric Heat-Producing Elements and Applications Thereof to Apparatus or Articles, of which the following is a specification.

My invention provides an improvedelectric heat producing element'distinctive by the use of carborundum arranged in said element so that an electric'current is passed through it.

I have ascertained by experiment that commercial carborundum i. e. carborundum in crystal condition initially offers .very great resistance to the passage through it of an electric current, and that after becoming heated develops a negative co-efficient of resistance, that is to say offers less resistance, so that it very quickly heats up and can be maintained at a given temperature at a low cost of electric power. Said carborundum is preferably a one piece part,

that is to say a block of solid carborundum chipped and hammered to size and shape, but it may be composed of a number of fairly large pieces in crystal form suitably held or pressed together without a binding agent, as distinct from granular carborundum.

I have also ascertained that the carborundum block or the like, and the electrically conductive contacts therewith should be arranged so as to be capable of being relatively set up to each other either automatically as by a spring or by hand to always ensure effective conductivity between said contacts and the carborundum, such being very necessary where the co-eiiicients of ex pansion and contraction of the carborundum and the contacts are substantially different.

My invention has many applications, such as in a vapourising and ignition plug or device for a semi-Diesel engine, as a heat producing element for a soldering iron, tea-pot, kettle, oven and such like, and as a heat producing element for radiators.

Two applications of the invention are represented by the accompanying drawings, one as a vapourising and ignition plug suitable for a semi-Diesel engine, and the other rundum block 'a is the heat producing sub stance arranged within the one end 0 of a steel casing 0 providing the body of the plug, this casing forming one of the electrical conductors. The centre rod (Z is the other electrical conductor. Said carborundumbloc-k is fashioned to size and shape to fit within the end 0 of the body which is a closed end as indicated ate but may have a hole 0 through 1t, as indicated by the dotted lines, to partly open said end. Said block is substantially circular in cross section as shown in Fig. 3 and makes direct conductive contact with the end of the casing and with the centre rodrl, but it may have applied between its diameter andthe inner sides of the casing end a tubular insertion of mica or asbestos so that it is substantially insulated from the casing end except at the closed end wall of the casing or at the end where through the hole 0 is provided.

Th casing is adapted at 0 for screwing into a hole of the cylinder of the semi-Diesel engine in a manner earthing the circuit.

The casing of the plug has applied to its hollow interior a porcelain bush 6 to serve as a mounting for the centre rod (Z which is clamped to the bush between a. packed collared end (Z of the rod and a clamping nut (Z pulling up with washers cl against the outer end of said bush. Said bush may be of any insulating material able to withstand heat.

The latter is applied to the casing 0 so as to be advanced towards the carborundum a by the tubular nut which engages the easing and encircles the bush; a packing material 9 being provided between the bush and the tubular nut Therefore the porcelain bush 0 is clamped within the casing between the tubular nut f and the inner end of the carborundum a, by the inner end of the V centre rod abutting hard against the carboirundum block to in turn clamp the carborundum piece'between'its end and the closed orpartially closed end of the casing.

It will be clear from Fig. 1 that good electrical conductive contact between the rod 4, end 0 of the casing and the carborundum block can always be made by a slight screwing up of the tubular nut f.

' It will be obvious that if a spring washer is combined with the packing 9 said washer may operate for automatically setting up the conductive contacts to the carborundum in case any looseness should developin actual use due to differential expansion and eon- V traction of the materials in touch.

The lead wire is connected to the outer end of the centre rod d in the ordinary way with sparking plugs, it being the binding terminal-tor saidrlead wire. 7

:With reference to Figs. 4 and 5 the carborundum block a is located within a socketlike carrier 0 suitably attached to some suitable part'd of the heat producing element, but between this carrier and the carborundum are provided tubular mica or asbestos :lengths e and f, and within the bottom of the socket a mica or asbestos disc 9. One of the'conductive contacts is a wire it engaging between the disc 9 and the end of the carborundum block a this wire passing at k between'the tubular pieces 6 and f and threading through an insulating bush 2' applied to the socket 0; through which bush also passes the other conductive contact j which bears hard against the outer end of the carborundum block a and is set up to it by the action of a 'ringnut Z applied to the socket to traverse the bush inwardly and maint-ain efiective electrical connection between the wire it and'the rod j. c

Having now described my inventlon what 'I' claim and desire to secure by Letters Patent is 1. An electric rheostat comprising a cas- 7 ing, a carborundum block within said casing, an electrode making pressure contact with said carborundum block and means for varying the pressure of said contact.

2. An electric rheostat comprising a casing, a ca-rborundum block carried within said casing, an electrode making pressure trode being provided with a collar intermediate its ends, a bush of insulating material surrounding said electrode and in abutment with said collar, and a screw threaded gland engaging said receptacle and bush, said gland being adjustable for-varying the pressure between said electrode and carborundum block.

In testimony whereof I have hereunto-set my hand in presence oftwo subscribing witnesses. r

CHARLES HENRY RO'DDIS Witnesses:

GEO. T. F UERY, JOHN P. FUERY.

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