US2264271A - Grounding connection - Google Patents

Description

. 2, 1941. A. BARNsTr-:INER

GROUNDING CONNECTION Filed Dec. 29, 1939 2 Sheets-Sheet l 2, 1941. A. BARNs-rr-:INER

GROUNDING CONNECTION 2 Sheets-Sheet 2 ril,...

Fin...

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ATTORNEY Patented Dec. 2, 1941 2,264,271 GIIOUNDING CONNECTION Alion: Barmteiner, Manleld, Ollio, signor to Westinghouse Electric Manufacturing Ccmpany, East Pittsburgh, Pa., a corporation of Pennsylvania Applicaon December 29, 1939, Serial No. 311,831

4 Claiml. (Cl. 21B-37) My invention relates to range heaters and more particularly vto a method of grounding such heaters.

Enameled supporting structures have been and are being used to a great extent for various types of heating units, such as range surface units and oven heaters, or the like. Safety requirements demand that such structures be grounded. A satisfactory grounding of such enameled structures requires that the grounding connection be rmly connected to the metallic base or understructure which, by necessity, due to the enamel protective coating thereon is formed of a corrosive metal.

Such connection has heretofore been made directly with the corrosive metallic structure, and although various methods have been employed to make the necessary grounding connection, in all cases a portion of the enamel protective coating was required to bc removed from the corrosive understructure. Quite frequently, the enamel has not been properly removed, thus leaving a portion of the base about the grounding connection without a covering of protective enamel. The corrosive metal is thus free to deteriorate, resulting in the possibility of the grounding connection becoming disengaged or electrically disconnected from the supporting structure. Such ungrounded structure is then a very dangerous hazard capable, under some conditions, of serious injury to an operator contacting it. y I

To overcome this serious hazard which has retarded the use of enameled heating unit supporting structures, I propose to utilize a non-corrosive electrically conducting grounding or contact member which may be rigidly attached to the corrosive supporting structure without the need of removing the protective coating from that structure.

' It is, therefore, an object of my invention to `provide a grounding device ior enameled structures which may be rigidly attached to such structures before applying the enameling coating thereto.

A further object of my invention is to provide a corrosive metallic enamel-adhering heatingunit-supporting structure with a metallic, noncorrosive, non-oxidizing, electrically conducting grounding or connecting device to which an enamel coating will not adhere, as a grounding device therefor.

Another object of my invention is to provide a method of grounding an enameled structure by attachingv a non-corrosive metallic member to such structure exclusive of such member and then connecting the desired grounding device to such member.

Still a further object of my invention is to provide a grounding member for an enameling structure which may be subjected to the usual enameling spray or dipping process but which will not retain the enamel coating during the baking operation whereby such coating will automatically be removed from the grounding member during such baking operation.

Other objects of my invention will either be pointed out specifically in the course of the following description of a device embodying my invention, or will be apparent from such description.

In the accompanying drawings:

Figure l is a bottom plan view of a heating unit embodying my invention;

Fig. 2 is a sectional view taken along the line II-II o! Fig. l;

Fig. 3 is a fragmentary, enlarged sectional view similar to Fig. 2;

Fig. 4 is a top plan view of an oven heating structure embodying my invention; and

Fig. 5 is an enlarged sectional view taken along the line V-V of Fig. 4.

Referring to Figs. l, 2 and 3 of the accompanying drawings, in which like reference characters indicate like parts in the several figures, I show a range surface unit heating structure Iii comprising an enameled supporting structure I2 and a heating element I4 rigidly attached to the structure I2, the enameled supporting structure I2 having non-corrosive metallic members I6a and I6b attached thereto for permitting the structure I0 to be adequately grounded.

The heating unit I0 is, in this instance, of a well-known structure in which the heating element I4 is formed of a plurality oi' complementary plates with electric resistors insulatedly positioned therebetween and is rigidly attached to a supporting pan-like structure I2 by means of a suitable bolt-like member I8. It is to be understood that any desired heating element may be used in lieu of element Il. The bolt-like member I8 is rigidly attached to or integral with the heating element I4 and depends'therefrom, at substantiallythe mid-point thereof. The bolt I8 is adapted to pass downwardly through a suitable insulating member 20 positioned within the pan I2 and through a centrally located aperture 22 in such pan structure I2. A suitable nut 24 is then positioned upon the lower end of bolt IB drawing the heating elesuch structure. applying a coating of enamel to ment Il down against the insulating member and pan structure I2 to form a functionally integral heating unit I0.

The enameled supporting structure I2 is formed of an oxidizing or corrosive enamel-adhering metallic sheet I3 in a well-known manner. Such metal is preferably a commercial vitreous enamel iron of rather high purity. By having the pan structure I2 formed of an enamel-adhering metal, such structure may be readily enameled in any well known manner. However, if the pan structure I2 be wholly enameled, it follows that the heating element I4 will be electrically insulated therefrom. Accordingly, to adequately ground the element and pan structure, it is necessary to provide electrically connecting means therebetween, as herein described. Suitable depending ears 26 are formed within the lower surface of pan structure I2 to permit a 'terminal block 28 to be rigidly attached theretoin a well-known manner. The terminal block 28 retains three ends of suitable terminal straps which are l onnected to terminals 32 of the heating element I4. The depending ears 26 are integral with the pan structure I2 and are `enameled therewith in the usual manner. These ears 26` retain the insulating block 28 by means of suitable through bolts 34 which pass therethrough.

Suitable non-corrosive, non-oxidizing, enamel-non-adhering, electrically conducting, washerllke members |6a and. I 6b are rigidly attached to the corrosive metallic sheet I3 used in forming the pan structure I2. These non-oxidizing washers are preferably of a high temperature copper nickel alloy which are lowin iron content such as is sold under the trade name Monel. The washers 16a and I6b are rigidly attached to the pan structure I 2in any desired manner. However, it is preferred that they be spot Welded thereto. One washer I6a is positioned about the aperture 22 coaxial therewith. A second washer I6b is positioned on one of the depending ears 26 of the pan structure I2 to provide means for connecting, say, grounding means to such structure.

After rigidly attaching the non-oxidizing enamel-non-adhering washers to the corrosive metallic base metal I3 of the supporting structure I2, such structure is enameled, usually by the spraying method, so as to provide a suitable enameled coating therefor. The enamel is then baked on in a well-known manner to provide a suitable non-corrosive, electrically non-conductive coating for the supporting structure I2. Some of the enamel coating will be deposited upon the washers during the spraying operation. However, inasmuch as the washers I6a and I6b are non-oxidizing and enamel-non-adhering, the enamel coating unintentionally sprayed upon the washers will not adhere thereto. Such enamel is drawn off the washers during the baking or ring operation because of the non-oxidizing and enamel-non-adhering characteristic of the washers by the surface tension of such enamel coating prior to solidication thereof. Accordingly, there will be no corrosive coating positioned upon the washers after the baking operation.

It therefore'follows that there will be an electrical connection between the uncoated, nonattached to the supporting structure I2 by means of the electrically conducting bolt I8, it follows that such element I4 is electrically associated with the metallic supporting structure I2, due to the bolt I8 being intimately associated with such element I4 at one end thereof and operatively associated with the metallic washer I 6 through nut 24 at the other end thereof. The heating element I4 is thus grounded to or electrically associated with the enamel coated structure I2.

The pan structure I2 is grounded by means of one of the elongated bolts 34 which rigidly attach the terminal block 28 to the supporting structure. The elongated bolt 34 passing through the washer I6b and terminal block 28 is rigidly attached thereto by means of a suitable ,wing-nut 36. A suitable grounding wire 38 may thus be positioned between the terminal block 28 and wing-nut36, so as to make electrical contact therewith. vThe enamel supporting structure I2 is thus grounded by means of wing-nut 36, elongated bolt 34 and non-corrosive washer I6b, which is rigidly attached thereto.

The heating element I4 is thus electrically associated with or grounded to the enamel coated supporting structure I2 by means of non-corrosive washer IIa. The combination structure of the supporting member I2 and heating element I4 is then grounded by means of the second washer I6b and wing-nut connection 36 to the grounding wire 38.

It is therefore obvious that I have provided an article of manufacture comprising an oxidizing, corrosive, enamel-adhering, metallic structure with a vnon-oxidizing, non-corrosive, electrical conducting, enamel-ncn-adhering member rigidly attached to said structure, and in electrical contact therewith, for providing means for grounding-the corrosive metallic structure or for attaching an electrical connection thereto, such structure but not said member being covered with a non-corrosive, electrically non-conducting, protecting coating.

Referring to Figs. 4 and 5, I show a second form of a protectively coated heating unit. Such yheating unit 40 comprises a Vmain structure 42 and a suitable heating element 44 insulatedly attached thereto. The heating unit 40 herein described and illustrated is more fully described and claimed in a copending application Serial No. 311,617, filed December 29, 1939, of E. H. Lockwood, assgned to the assignee of this application. The structure 42 is likewise formed of a corrosive enamel-adhering metallic sheet 46,-

l terial as washers I6a and I6b) is rigidly attached to the corrosive sheet 46 about 'the aperture 48 in electrical communication therewith.

The corrosive enamel-adhering sheet 46, with the metallic washer 50 attached thereto, is then enameled in any desired manner, such as by spraying. However, due to the washer 50 being enamel-non-adhering, the en'amel coating 52 will not remain upon such washer, as hereinabove described. Such enamel coating Will, however, extend down within the aperture 48 adjacent the washer 5U. l

It, therefore, follows that any desirable and suitable grounding member 54 may be rigidly attached to the washer 50 so as to be in electrical communication with or ground the enameled supporting structure 42 of the heating unit Il).

It is, therefore, obvious that I have provided a method of grounding an enameled or protectively coated corrosive metallic structure which permits such structures to be grounded without the need of wiping or removing the protective coating therefrom at any stage of the process of coating such structures. Further, that such grounding member will permit any desired or necessary grounding structure to be rigidly attached to the corrosive metallic structure without harming the protective coating thereon.

It is to be understood that the electrical connection with the enameled structures, through the medium of the enamel-non-adhering members attached thereto, need not be for grounding purposes alone but may be used for making any desired electrical connection with an enameled structure,

Various further modifications may be made in devices embodying my invention without departing from the spirit and scope thereof, and I desire, therefore, that only such limitations shall be placed thereon as areimposed by the prior art and the appended claims.

I claim as my invention:

1` An article of manufacture comprising a corrosive metallic structure, a non-corrosive member rigidly attached to such structure and in electrical contact therewith, said structure alone being covered with a non-corrosive protecting coating, and contact means attached to said member for making electrical contact with the structure.

2. An article of manufacture comprising a grounding member, a corrosive metallic structure, having an aperture therethrough for permitting the grounding member to pass therethrough, a non-corrosive electrical conducting member attached to said structure adjacent the aperture and in electrical contact therewith, said structure alone being covered with a non-corrosive electrically non-conducting protecting coating, and said grounding member passing through the aperture and engaging the non-corrosive member rigidly attached to the structure for ground- .ing such non-corrosively coated structure.

3. A heating unit comprising, in combination, a heating element, a corrosive metallic supporting pan structure, a plurality of non-corrosive metallic members rigidly attached to the pan structure in electrical contact therewith, a non-corrosive electrically non-conducting enamel coating covering such pan structure alone,v means for attaching the heating element to such pan struc-4 ture, said means engaging one of the non-corrosive members for grounding such element to the pan, and means comprising a second noncorrosive member for grounding the pan structure and heating element. A

4. A heating unit comprising, in combination, a heating element, a corrosive metallic heat shield adapted to' support such element, a non-corrosive metallic washer rigidly attached to the shield coaxially with an aperture therethrough, a noncorrosive electrically non-conducting enamel coating covering the shield alone, a grounding bolt passing through the washer and aperture,4

and nuts threaded upon such bolt for rigidly attaching it to the shield and washer for providing electrical connection from such bolt to the washer and shield.

ALFONS BARNSTEINER.

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