US2799766A - Electric heating unit - Google Patents

Description

July 16, 1 957 111V, TUTTLE n 2,799,766

ELECTRIC HEATNG UNVIT Filed March 31, 1955 l f7 f6 hired States Patent ELECTRIC HEATING UNIT Daniel V. rll`uttle, Kirkland, Ill., assignor, by mesne assignments, to Tuttle Electric Products, Inc., Kirkland, lll., a corporation of Illinois Application March 31, 1955, Serial No. 498,386

7 Claims. (CI. 219-37) This invention relates to electric heating units which are particularly adapted for use in electric ovens and for similar purposes and wherein the heating element thereof is supported by and extends lengthwise within a trough shaped shell which extends circuitously sidewise in the form of a at loop and has the opposite ends thereof secured to a bracket which supports the terminals through which current is supplied to the heating element.

The present heating unit is similar to that of my copending application Serial No. 436,469 which was tiled June 14, 1954, but contemplates improvements in the circuitous form of the ilat loop of the heating unit and the provision of facilities for reinforcing the loop to insure adequate strength and rigidity thereof.

The principal objects of the present invention are, to provide an improved form and construction of heating unit of the above mentioned type; to construct the unit with a single rectangular loop in which the trough shaped shell thereof may be made of thin sheet material with assurance of adequate strength and rigidity to retain the flat rectangular loop form; and to provide simple and convenient facilities for reinforcing the at rectangular loop, these and other objects being accomplished as pointed out more particularly hereinafter and as shown in the vaccompanying drawing, in which:

Fig. 1 is a plan view of the improved heating unit looking at the closed side thereof;

Fig. 2 is a side elevation of the heating unit;

Fig. 3 is a sectional elevation on an enlarged scale of the heating unit taken on line 3-13 of Eig. l, with an intermediate part thereof broken away;

' Fig. 4 is an enlarged fragmentary sectional view taken on the line 4-4 of Fig. l and showing a portion of the reflector unit with insulator and resistancewre therein; and

Fig. 5 is an `enlarged cross sectional view taken on the line 5--5 of Fig. l.

As shown in the drawing, which illustrates a preferred form of the invention, the heating unit is in the form of a at rectangular loop with an elongated trough shaped shell bent sidewise in the rectangular loop .form and serving as a supporting frame and reflector for an elongated heating element which is supported by and extends lengthwise in the trough shaped shell through insulators which are provided in the shell at spaced intervals throughout the length thereof. This trough shaped rectangular supporting frame, which -is indicated as a whole at 12, is composed of a series of sections of sheet metal of `arcuate 'cross section, as shown .n Fig. 5, Secured to one another in end to end relation, some of which said sections are straight lengths, as indicated at 10, and are used for the sides of the rectangular loop and others of which are elbows, as indicated at 11, and are interposed between straight lengths to form the corners of the rectangular loop.

These sections 1d and 11 do not form a complete loop, one side of the rectangular frame 12 being composed of `two straight sections 10 which extend 'toward one another tie ice

and have the inner ends thereof, indicated at 13, spaced apart so that the loop is incomplete at that place, and the inner ends 13 are secured to a pair of arcuate anges 14 of a bracket 15 which is interposed between the ends 13 and serves to complete the loop.

The ends 13 may be secured to the bracket 15 and 'the sections 10 and 11 to one another in any desired manner, as for example by telescoping the ends of the sections 10 inside the flanges 14 and inside the ends of the elbow sections 11 and brazing or welding the telescoped parts together, as indicated at 16. Preferably the sections 10 and 11 and the bracket 15 `are of stainless steel or other suitable metal the surface of which remains bright and heat rellective and does not rust or corrode as a result of heat and humidity.

The sections 10 and 11 are formed at 'appropriate ntervals with transverse corrugations or beads 17 of V-cross section to receive cermaic insulators 18 or the like by which the heating element, which is indicated at 21, is supported in the trough shaped frame 12, the corrugations or beads 17 of the elbow sections 11 being suiciently Vclose to one another to train the heating element safely through the bend, and each insulator 18 is V-edged, as indicated at 19, around the periphery to tit in the corrugations or beads 17 and has a central opening 22 through which the heating element 21 extends.

The arc of the cross section of the sections 10 and 11 is sufficiently greater than a semi-circle, for example ranging from to 230, so that the lateral edges of the said sections are inturned toward one another suffi ciently to retain .the insulators 18 in the corrugations or beads 17, the side walls of the sections 10 and 11 being suciently springy to be spread apart to install the insulators in and remove them from the corrugations or beads 17, it being important, however, that the arcof the cross section of the sections 10 and 11 be suiciently limited to leave a wide side opening from the sections 10 and 11 for exposure of the heating element, air circulation, and exit rof heat rays from the interior of said sections.

The bracket 15 not only serves to connect the inner ends 13 of the two sections 10 at that side of the loop and to complete the loop, but also serves as a support for terminals through which current is supplied to the heating element.

For the latter purpose a block 25 of ceramic or other suitable electrical insulating material is secured by bolts 26 to the bracket 15 between flanges 24 depending from the bracket and this block serves as a mounting for the heating unit terminals.

If the heating unit is to operate at 220 voltage, three terminals 28, 29 and 30 are employed which extend through separate openings in the block 25. The center terminal 29 is grounded to the bracket l5 and secured in its said opening of the block by a screw 31 which ex- 'tendspthrough a bolt hole in the bracket 1:3' and into an aligned bolt hole of the block 25 and is engaged in a threaded opening of the terminal 29. Y

The other two terminals 28 and 30 have the opposite vends of the heating element 21 connected respectively thereto by screws 32 at their inner ends and each terminal 28 and 30 has a struck 'out lug 33 at the outer end of the ,block 25 which cooperates with the respective screw 32 at the inner end of the block 25 to retain the terminal in the block 25, the screw k32 preventing withdrawal of the terminal in one direction from its opening in the block 25 and the lug 33 preventing such withdrawal thereof in the other direction.

For theppurpose of reinforcing the heating unit frame 12 to hold it rigidly in the llat rectangular loop form, a U-shaped brace 35 is provided which has an intermediate bent portion secured to the bracket 15 and a pair of legs extending 'from said bracket to the opposite side of the rectangular loop, as shown particularly in Fig. 1, and these legs are secured at their outer ends to the section at that opposite side ofthe loop by welding as at 38. g The outer ends ofthese legs are preferably groundaoiltoha curve asat 39 for the purpose of appearance. Y.

Another brace 36 extends crosswise of the legs of the U-shaped brace 35 and is secured to said legs by welding, as at 40, and this cross brace 36 is secured by welding, as indicated at 41, to straight sections 10 of the frame 12 which are at opposite sides of the U-shaped brace 35.

The opposite ends of the cross brace 36 are preferably extended downwardly at the outer side of the frame 12 below said frame and the insulators therein to provide legs 42 for supporting the heating unit on a surface 43, such, for example, as an oven bottom. Also, bolts Z6 are employed for fastening the insulating block 25 to the bracket 15, which said bolts are long` enough to project downwardly to the same level as the. legs 42, as shown in Figf2, and thus provide supports at the bracket 15 location which cooperate with the legs 42 to hold the heatin unit in a horizontal portion on the surface 43.

The surface 43 is representative of the bottom of an oven in which the above described heating unit is adapted to be used, land when so used the frame 12 not only serves to shield the heating element from drippings whichmay occur in the baking operation but also acts as a reflector to dissipate and distribute the heat throughout the entire oven.

This heating unit may also be used at the top of ran oven or at any other desired location therein and is also usable for many other purposes, as for example in clothes driers, space heaters, incubators, brooders, coffee roasters, furnaces, fruit ripening rooms, hot plates, broilers, enamel baking ovens, and for range burners.

The sectional construction of the frame 12 is particularly advantageous as the heating unit may be made in any desired size and rectangular shape and without requiring secured'to vsaid spacedapart ends to complete the loop and provided with a plurality of terminals thereon' through which current is suppliable to energize said heating element, said frame being composed of a series of elongated thin walled trough shaped sections secured to one another in end to end relation, the said terminal support being located at one of two opposite sides of the loop between two of said sections and having secured thereto one end of a brace which extends therefrom across the loop and is secured at the other one of said two opposite sides of the loop to another trough shaped section of the frame, and the said frame having two others of the said sections thereof located respectively at opposite sides of said brace and secured to another brace which extends crosswise of and is secured to the first mentioned brace.

3. An electrical heating unit of the class described Y comprising an elongated trough shaped frame fashioned any additional or special dies as all such sizes and shapes are made with the same elbows 11 and also with straight lengths 10 which are the same except for diiference in length.

Moreover, by reason of the particular bracing employed, unusually thin sheet material may be used for the frame sections 10 and 11 without danger of warping or distortion and thus the performance and efficiency of the heating unit is improved and the cost thereof minimized.

While I have shown and described my invention in a preferred form, I am aware that various changes and modifications may be made therein without departing from the principles of the invention, the scope of which is to be determined by the 'appended claims.

What is claimed is:

l. An electrical heating unit of the class described comprising an elongated trough shaped frame fashioned sidewise in the form of an incomplete loop with spaced apart ends and having an elongated electrical heating element mounted therein and extending lengthwise thereof, and a terminal support which is interposed between arid secured to said spaced apart ends to complete the loop and provided with a plurality of terminals thereon through which current is suppliable to energize said heating element, said frame comprising an assembly of a plurality of elongated thin walled trough shaped sections which are connected to one another in end to end relation to form the frame, the said terminal support being located at one of two opposite sides of the loop-between two of said sections and having attached thereto one end of an elongated brace which extends therefrom across the loop and is attached at the other one of said two opposite sides of the loop to another trough shaped section of the frame.

2. An electrical heating unit of the class described comprising an elongated trough shaped frame fashioned sidewise in the form of an incomplete loop with spaced apart ends and having an elongated electrical heating element mounted therein and extending-lengthwise thereof, and a terminal supportI which is interposed between and sidewise in the form of an incomplete loop with spaced apart ends and having an elongated electrical heating element mounted therein and extending lengthwise thereof, Vand a terminal support which is interposed between andsecured to said spaced apart ends to complete the loop and provided witha plurality of terminals thereon through which current is suppliable to energize said heating element, said .frame being composed of a series `of elongated thin walled troughshaped sections secured to one another in end to end relation, the said terminal support being located at one of two opposite sides of the loop between two of said sections and having secured thereto one end of .a brace which extends therefrom across the loop and is secured at the other one of said two opposite sides of the loop to another trough shaped section of the frame, and the said frame having two others of the said sections thereof located respectively at opposite sides of said brace and secured to another brace which extends crosswise of and is secured to the first mentioned brace, one of said' braces having the opposite ends thereof extending downwardly below the frame to form supporting legs for theheating unit.

4. An electricalheating of the class described comprising an elongated trough shaped shell shaped sidewise in the form of an incomplete at rectangular loop with spaced apart ends and having an elongated electrical heating element mounted therein and extending lengthwise thereof, and a terminal support which is interposed betweenand secured tosaid spaced apart ends to complete the loop and provided with a plurality of terminals thereon through which current is suppliable to energize said heating element, .said shell being composed of a series of elongated thin walled trough shaped sections secured to one another. inend 'to end relation, some of which said sections are straight lengths and others of which are elbow shaped .and .interposedbetween straight length sections to provide the rectangular form of the loop, the said terminal supportbeing secured between two o'f said straight lengths, and connected by a brace to another of said straight lengths at the opposite side of the loop, and said shell having two others of its straight lengths located re, spectively at opposite sides of and substantially equidistant from said'brace and' secured to a tie rod which extends crosswise of and is secured to said brace between the ends of the. latter.

5. An electrical heating unit of the class described comprising an elongated thin walled trough shaped shell shaped sidewise in the form of an incomplete flat rectangular loop with spaced apart ends and having an elongated electrical heating element mounted therein and extending lengthwise thereof, a terminal support which is interposed between and secured to said spaced apart ends to complete the loopand provided with a plurality of terminals thereon through which current is suppliable to energize said heating element, and means for reinforcingand maintaining the elongated thin walledtrough shaped shellin the :aforesaid ilat rectangular -loop form which said means comprises two braces which extend Crosswise of and are secured to one another and to the four sides of the rectangular loop with one end of one of said braces secured to the aforesaid loop completing terminal support thereof, the said shell having a series of insulators therein which have the heating element extending therethrough and are spaced apart at intervals throughout the length of the shell and the shell having opposed resiliently separable side walls by which the insulators are releasably retained individually in the shell.

6. An electrical heating unit of the class described comprising an elongated trough shaped shell extending sidewise in the form of an incomplete loop with spaced apart ends and having an elongated electrical heating element mounted therein and extending lengthwise thereof, and a terminal support interposed between and secured to said spaced apart ends to complete the loop and provided with a plurality of terminals thereon through which current is suppliable to energize said heating element, the said terminal support having secured thereto one end of a brace which extends therefrom across the loop to the opposite side thereof and is secured to the portion of the shell at that side of the loop, the said end of the brace being in the form of a loop and the terminal support being composed of two parts one of which is provided with a seat in which the loop of said brace is clamped bythe other one of said two parts.

7. An electrical heating unit of the class described comprising an elongated trough shaped sheet metal shell extending sidewise in the form of an incomplete loop with spaced apart ends and having an elongated electrical heating element mounted therein and extending lengthwise thereof, a sheet metal terminal support which s interposed between and secured to said spaced apart ends to complete the loop and has attached thereto a block of electrically non-conductive material provided with a plurality of electrically conductive terminals through which current is suppliable to energize said heating element, and a U-shaped brace which has a bent midportion secured to said sheet metal terminal support and two legs extending therefrom across the loop to the opposite side thereof and secured to the portion of the shell at that side of the loop, the said sheet metal terminal support being formed with a seat in which the bent midportion of the U-shaped brace is secured as aforesaid by said block of electrically conductive material.

References Cited in the file of this patent UNITED STATES PATENTS 2,619,780 Gough NOV. 5, 1935

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