US2721247A - Multiple electric heater assembly - Google Patents

Description

I. G. GLENN MULTIPLE ELECTRIC HEATER ASSEMBLY Oct. 18, 1955 5 Sheets-Sheet 1 Filed April 1, 1953 INVENTOR.

IRVING G. GLEN/V A TTOR/VEV Oct. 18, 1955 l. s. GLENN MULTIPLE ELECTRIC HEATER ASSEMBLY I5 Sheets-Sheet 2 Filed April 1 1955 FIG. 4

INVENTOR.

IRV/NG 6. 6L E/VN i/lzzer H pm J ATTORNEY Oct. 18, 1955 1. G. GLENN MULTIPLE ELECTRIC HEATER ASSEMBLY 3 Sheets-Sheet 5 Filed April 1 1953 8 G I F INVENTOR.

lRV/NG G. GLENN ATTORNEY United States Patent MULTIPLE ELECTRIC HEATER ASSEMBLY Irving G. Glenn, New York, N. Y.

Application April 1, 1953, Serial No. 346,137

6 Claims. (Cl. 201--67) This invention relates to a flexible electric heating unit assembly, in which a plurality of electric heating elements, eifectively insulated, individually, from each other, are assembled in close, compact relation, against displacement, in a single metallic sheath. This application is a continuation in part, of my co-pending application, Serial No. 248,197, filed September 25, 1951, which matured in U. S. Patent No. 2,639,359, granted May 19, 1953.

The object of the invention is to provide, in a single flexible sheathed unit of minimized cross sectional dimensions, that enables it to be safely bent cold into any form desired to meet all structural use requirements, means for obtaining better electric heat control, such for example, as three phase, when required, or by switching to series or multiple, high-low and other variations. To facilitate assembly and insure maintenance of effective insulation against hot spots, shorts or burn-outs, particularly when the unit is bent cold on short radius, for which it is flexibly adapted, the heating elements before assembly, are fitted snugly, individually or collectively, in a preformed tubular insulator of chalky porcelain or like frangible material which, as preformed, is of maximum dimensions attained in its use.

The tubular insulators are externally ribbed lengthwise and may be preformed as single tubes, to serve separately for each single heater element or multitubular, to serve for a number of the elements. When a plurality of the assembled heater elements, insulated, as described, are entered in the metallic sheath, they fill the greater portion of the bore thereof and the ribs of the single tube insulators intermesh in interlocked relation, at the point of meeting, securing the several assemblies against individual or collective displacement.

In addition to the interlocking action, above memtioned, between the ribbed single tube insulators, the

sheath closely encircles a portion of each insulator, opposite the intermeshed ribs of the same and aids materially in maintaining them properly positioned against displacement and resulting destructive shorts, burn-outs, etc. With the multitubular insulator, the heating elements are held in definite, fixed relation against possible movement or displacement.

As assembled, two ribbed walls of the single tube insulators are interposed between each pair of adjoining heater elements, thereby insuring ample insulation in the unit.

With the essential elements of the unit assembled, as described, the unoccupied space, within the sheath, is filled with powdered or granular insulating material, such as magnerite or the like and, after the sheath is sealed about the projecting terminals of the electric heating elements, in a conventional manner, the unit is completed by machine swaging, rolling mill, press or other pressure operation, which crushes and compacts the insulating material employed solidly in and about the heating elements and the unit is ready for use.

As the circuit wiring connections and control switch for utilizing the unit to obtain desired current variations are conventional, they will not be further described.

The accompanying drawings will serve to illustrate several constructions, suitable for carrying the invention into effect, but it will be understood that no limitations upon the invention are intended by this showing, other than are imposed by the scope of the appended claims.

It will be noted that the drawings are on a greatly enlarged scale and that relative proportions are considerably exaggerated, as believed necessary, for clearness of illustration.

In the drawings-- Fig. 1 is a perspective view of a short length of a twoelement heater unit assembly, before being pressure processed, with portions broken away to show the compact relation of the parts and the intermeshing ribs of the single tube insulators.

Fig. 2 is a cross section of the same, on the line S S of Fig. 1.

Fig. 3 is a view similar to Fig. 2, showing a threeheater element assembly.

Fig. 4 is a top plan view of Fig. 1, showing a modification, in which the helically-wound heating elements are formed of ribbon wire, instead of round wire, as in the other views.

Fig. 5 is a cross section showing three heater elements arranged in triangular formation.

Fig. 6 is a view similar to Fig. 1, showing a further modification, which consists in preforming the insulator as a multitubular member, for use instead of the single tube insulators, shown in the other views.

Fig. 7 is a cross sectional view of the same, on the line S S of Fig. 6.

Fig. 8 is a similar view, showing a three-heater element form, and

Fig. 9 is a like view, showing of the three elements.

Referring now to the drawings, 1 indicates the heating elements, of which there are at least two and more may be employed if desired. They are ordinarily of conventional form, that is to say, helically wound or otherwise formed of round or ribbon wire, preferably the latter, as shown in Fig. 5 and are provided, in the usual manner with terminals for connection in circuit with a suitable control switch (not shown).

Each heating element, as shown in Figs. 1 to 5, is individually enclosed in a preformed tubular insulator 2 of chalky porcelain or like frangible material and, as preformed, is of maximum dimensions attained in use. EX- ternally, each insulator is ribbed lengthwise, as indicated at 3, and when a heating element is entered in a tubular insulator, it snugly fits the bore thereof.

Two, three or more of the heater element and tubular insulator assemblies are enclosed in closely associated relation, in a metal sheath or jacket 4, filling the greater portion of the same and leaving comparatively little unoccupied space therein.

The close association of the several assemblies within the sheath, results in the ribs of the insulators intermeshing and interlocking, in co-operative relation, as indicated at 5, to securely bind the assemblies together and against any movement or displacement, likely to cause hot spots, shorts, burn-outs or other damage.

The firm anchorage of the several assemblies, individually and collectively, within the sheath, is especially important, particularly when the unit is bent cold on a short radius and contributing to the safety factor, under such circumstances, the metal sheath is shaped to closely embrace and partially encircle each ribbed insulator opposite the meeting point of the intermeshing ribs, as indicated at 6.

a triangular assembly As assembled in the sheath, two ribbed walls of the insulators are interposed between adjoining heating elements, which eflectively isolates and insulates them from each other, without appreciatively reducing the flexibility of the completed unit.

After the unoccupied space within the sheath is filled with granular or powdered magnerite, or like material, as indicated at 7, and the sheath is closed and sealed about the projecting terminals of the heating elements, in a conventional manner, the completely assembled unit is subjected to a machine pressure operation.

The final step results in crushing the preformed insulatorsand compacting them and the granular magnerite solidly in and about the several heating elements and the unit is ready for use.

The modification shown in Figs. 6 to 9, consists in providing a multitubular insulator 8, preformed in one piece, as a substitute for the single tube insulators above described.

'The tubular openings for the insertion of the heater elements are indicated at 9 and the insulator, as preformed of the material above described, is ribbed lengthwise, as indicated at 10.

The sheath 11 fits snugly around the ribbed surface of the insulator and the unoccupied space within the sheath is filled with granular insulating material, indicated at 12. The completed assembly is then subjected to a machine pressure operation, with a result as above described.

Among the prominent features of the invention may be mentioned the following:

The employment of a plurality of heating elements in a single sheath, enabling any desired current variations to be obtained at will.

The arrangement of the heating elements in such close relation, that with several elements active, they mutually co-operate to effect rapid heating of the unit at less expenditure of current than would be possible with a single element and, any approach to instantaneous heating, is highly desirable.

With several elements available and active for quick initial heating of the unit, it may thereafter be maintained at the required temperature by a single element, with a resulting saving of current.

With one element active, it will raise the temperature of the other closely associated element or elements sufficiently to cause it or them, when connected in circuit, to reach maximum temperature almost instantaneously and save considerable time and current in heating the unit as required.

If, for any reason, one element fails to heat up, another or others are available, so the unit is not seriously in- 'capacitated and may be continued in effective use.

The close association of the heating elements gives rise to the further advantage that the overall cross sectional dimensions of the unit are reduced to a minimum and its flexibility maintained, which enables it to be bent cold on any radius to meet structural use requirements.

Preforming the insulator in one piece, as a multitubular member, saves time and labor in manufacture, as well as in assembly of the unit and gives rise to many other advantages, that will be obvious.

I claim:

1. A flexible electric heating unit assembly, comprising a plurality of electric heating elements, frangible insulating material preformed externally ribbed and internally shaped to receive, conform to and completely enclose the several heating elements in separated relation at definite distances apart but leaving the terminals thereof exposed for circuit connection, a metal sheath smooth surfaced internally and externally and closely fitted to the ribbed surface of the aforesaid preformed insulating material and a filling of granular insulating material in the unoccupied space within the sheath, the ends of which are sealed for subsequent pressure procmaterial in and about several electric heating elements enclosed in a metal sheath, comprising a plurality of electric heating elements, frangible insulating material preformed externally ribbed and internally shaped to receive, conform to and completely enclose the several heating elements in separated relation at definite distances apart but leaving the terminals thereof exposed for circuit connection, a metal sheath smooth surfaced internally and externally and closely fitted to the ribbed surface of the aforesaid preformed insulating material and a filling of granular insulating material in the unoccupied space within the sheath,- the ends of which are sealed for subsequent pressure processing of the unit, the unit when completed being flexible and permitting cold bending on any radius without displacing the heating elements.

3. A flexible electric heater unit assembly, comprising a plurality of electric heating elements, a tubular liner preformed externally ribbed lengthwise of frangible insulating material for each of the heating elements, through the bore of which the said elements extend snugly fitted therein with the ends thereof projecting from the liners, the said liners as preformed ribbed lengthwise being for temporary use of the same in assembling and positioning the elements of the heater and adapted in the completed assembly to be thereafter crushed and compacted about the heating elements, an outer tubular jacket in the bore of'which the several heater element and liner assemblies are entered filling the greater portion of the same, with the external ribs of the liners intermeshing and interlocking to positively position the assemblies in definite spacedapart relation from each other therein, a filling of granularinsulating material in the unoccupied space within the jacket and suitable closures for the ends of the jacket, the unit when completed being flexible and permitting cold bending of the same on any radius without displacing the heating elements.

4. A flexible electric heater unit assembly, comprising a plurality of electric heating elements, a tubular liner preformed externally ribbed lengthwise of frangible insulating material for each of the heating elements, through the bore of which the said elements extend snugly fitted therein with the ends thereof projecting from the liners, the said liners as preformed ribbed lengthwise being for temporary use of the same in assembling and positioning the elements of the heater and adapted in the completed assembly to be thereafter crushed and compacted about the heating elements, an outer tubular jacket in the bore of which the several heater element and liner assemblies are entered filling the greater portion of the same, with the cxternal'ribs of the liners intermeshing and interlocking at their meeting surfaces to positively position the aforesaid'assemblies in definte spaced-apart relation from each other therein and being closely encircled partially at their outer surfaces opposite the meshed ribs by the wall of the tubular jacket, a filling of granular insulating material in the unoccupied space within the jacket and suitable closures for the ends of the jacket, the unit when completed being flexible and permitting cold bending of the same on any radius without displacing the heating elements.

5. A flexible electric heater unit assembly, comprising a plurality of electric heating elements, a tubular liner preformed externally ribbed lengthwise of frangible insulating material for each of the heating elements, through the bore of which the said elements extending snugly fitted therein with the ends thereof projecting from the liners, the said liners as preformed ribbed lengthwise being for temporary use of the same in assembling and positioning the elements of the heater and adapted in the completed assembly to be thereafter crushed and compacted about the heating elements, an outer tubular jacket in the bore of which the several heater element and liner assemblies are entered filling the greater portion of the same, the external ribs of the liners intermeshing and interlocking at their contacting surfaces to position the aforesaid assemblies in definite spaced-apart relation therein from each other with the two ribbed walls of the meeting liners interposed between the heating elements, a filling of granular insulating material in the unoccupied space within the jacket and suitable closures for the ends of the jacket, the unit when completed being flexible and permitting cold bending of the same on any radius without displacing the heating elements.

6. An assembly for forming a flexible electric heating unit preliminary to processing the same by a pressure operation to crush and compact the contained insulating material employed solidly in and about a plurality of electric heating elements and permanently position the same positively in definite spaced-apart relation from each other and from a metallic sheath enclosing the unit, the said assembly comprising a plurality of helically-wound electric heating elements, a tubular liner preformed externally ribbed lengthwise of frangible insulating material for each of the heating elements through the bore of which the said elements extend snugly fitted therein with the ends thereof projecting from the liners, an outer tubular jacket in the bore of which the several heater element and liner assemblies are entered filling the greater portion of the same, with the external ribs of theliners intermeshing and interlocking to positively position the assemblies in definite spaced-apart relation from each other, a filling of granular insulating material in the unoccupied space within the jacket and suitable closures for the ends of the jacket, the unit when completed, being flexible and permitting cold bending of the same on any radius without displacing the heater elements.

References Cited in the file of this patent UNITED STATES PATENTS 1,905,232 Kercher et al. Apr. 25, 1933 1,927,035 Hicks Sept. 19, 1933 1,982,885 Stupakoff Dec. 4, 1934 2,577,080 Glenn Dec. 4, 1951 2,639,359 Glenn May 19, 1953 FOREIGN PATENTS 503,495 Great Britain Apr. 5, 1939 528,718 Great Britain Nov. 5, 1940

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