US2963539A - Insulator assembly for electric resistance heater - Google Patents

Description

Dec. 6, 1960 P. HYNES 2,963,539

INSULATOR ASSEMBLY FOR ELECTRIC RESISTANCE HEATER Filed Feb. 28, 1958 l INVENTOR United States Patent O 'INSULATOR ASSEMBLY FOR ELECTRIC RESISTANCE HEATER Lee P. Hynes, Haddonfield, N.J., assignor to The Hynes Electric Heating Co., Mountainside, N.J., a corporation of New Jersey Filed Feb. 28, 1958, Ser. No. 718,244 1 Claim. or. 174-138) The present invention relates to electric resistance heaters and particularly for improved insulator assemblies for such heaters.

A purpose of the invention is to permit ready replacement of an insulator in an electric resistor assembly without disassembling the resistors.

A further purpose is to permit the use of interchangeable parts forming at least two portions of each resistor assembly, simplifying the construction and rendering it less expensive.

A further purpose is to build up the insulator assemblies from stacks of insulators held by a clip which at one end extends through a longitudinal slot of a flexible metallic support and is anchored by bending over beyond the support, which intermediately extends through longitudinal slots in the insulator elements, and which beyond the topmost insulator element is bent over to secure the combination.

A further purpose is to anchor the insulator combination by clips consisting of multiple strips fastened together and bent at the ends in opposing relation.

Further purposes appear in the specification and in the claim.

In the drawings I have chosen to illustrate one only of the numerous embodiments in which my invention may appear, selecting the form shown from the standpoints of convenience in illustration, satisfactory operation and clear demonstration of the principles involved.

Figure 1 is a transverse section through an electric heater of the invention omitting the electric heater elements.

Figure 2 is a section on the line 2-2 of Figure 1, omitting the casing but including the electric heater elements.

Figure 3 is a top plan view of the structure of Figure 2.

Figure 4 is an exploded perspective of the insulator assembly.

Figure 5 is a fragment of Figure 1 showing a variation.

Figure 6 is a view corresponding to Figure 1 showing a further variation. The view is broken away to indicate that the column of insulator elements may be of any desired height.

Describing in illustration but not in limitation and referring to the drawings:

In my U.S. Patents 1,997,146, granted April 9, 1935, for Electric Heater; 2,536,747, granted June 2, 1951, for Electric Resistance Heater and Heated Vessel; and 2,750,487, granted June 12, 1956, for Electric Heater, I illustrate heaters of the character which can be employed for melting ice on hydroelectric dam gates or the like, for heating fluids, and generally for electric heating especially where the heater has an appreciable length.

The present invention includes an improved insulator assembly which offers several advantages. In the constructions of my prior inventions, if an insulator broke or if the heater required modification and an insulator needed "ice to be removed, it was usually necessary to remove the electric heater elements before removing the insulator. Also in the prior art construction, each of the insulators was a single element, and the cost of producing the same was considerable.

By the present invention, it is possible to replace an individual insulator or a part thereof without removing the resistors from the insulators. It is also possible in the present invention to replace only a part of an insulator.

The cost of production of the insulator is greatly reduced by making two of the three parts of each insulator from interchangeable elements which can be used alternatively either as the bottom or the top.

The assembly is greatly simplified in the device of the invention with respect to the prior art because if desired the lower resistors can be introduced before the insulators are fully assembled.

By means of clips having opposed bent ends, I am able to obtain a more sturdy and simple assembly of insulators.

As shown in the drawings, a flexible metallic supporting strip 20, suitably of steel, extends longitudinally of the resistor. The top of the strip engages the bottom of lower insulator element 2 1 which'in turn at its top en-' gages the bottom of middle insulator element 22, and the middle insulator element at its top engages the bottom of top insulator element 23, the insulator elements cooperatively forming a stack. The top and bottom surfaces of the insulator elements are suitably flat as best seen in Figures 1 and 4, the middle insulator element suitably has flat ends 24, and the top and lower insulator elements have arcuate or curved ends 25 which make the outer contour of the stack generally circular, so that the I two sets, an upper set 30, 31, and a lower set 32, 33..

All of the holes 36 for example of the various insulators are in line, and also each of the holes 30, 31, 32 and 33 has radial and longitudinal slots 35 at the horizontal sides which permit insertion and anchoring of strip resistors rather than helical resistors if these are preferred, and insertion of terminal strips.

At the middle and therefore offset from or out of line with the resistors and the resistor openings, each of the insulators has a transverse and longitudinally extending slot 36 in the top and lower insulator elements and 37 in the middle insulator elements, the slots all being in line from top to bottom and also in line with a lateral and longitudinally extending slot 38 in the metallic strip 20 at each insulator position.

The respective slots 38, 36, 37 and 36, when in line, receive a metallic clip 4t which is preferably formed of two metallic strips 41 suitably of steel, side by side throughout the intermediate portions of their length and united as by spot welding at 42 near the top and bottom. The clip extends beneath the flexible metallic strip 20 and has two opposed or oppositely bent ends 43 which anchor beneath the strip 20. Likewise the clip beyond the top insulator element has two opposed or oppositely bent ends 44. The top insulator element has recesses 45 on either side of the slot 36 and these recesses are tapered and become deeper progressively away from the slot 36. The opposed ends 44 thus are bent into acute angles and lie against the tapered portions of the recesses 45, thus protecting against springback which might cause the ends 44 to interfere with or engage the wall of the casing 26. This is important because the ends 43 will suitably be prebent but the ends 44 will be bent at assembly and the amount of pressure which should be applied to the ends 44 is somewhat limited by the fact that the insulator elements will suitably be formed of porcelain, ceramic material or the like. Thus it is possible to obtain a tight engagement which holds the insulator elements in place without danger of causing excessive pressure which would break the insulator elements.

In operation, the clip 40 is assembled through the bottom of the flexible metallic strip 20, the ends 43 suitably being prebent as shown. The insulator elements are then assembled by threading them on the clip 40 until the stack is formed, and then the top ends 44 are bent into the acute angled position shown in Figure 1, using either a suitable wedge tool or a suitable press. With the various insulators assembled, the resistors are threaded through the longitudinal holes and the resistors are electrically wired together. Then the entire resistor and insulator assembly is inserted in the casing,

Figure 5 shows an insulator stack at one end of the resistors which supports a terminal strip 46 in the edge slots 35 and across the opening 33, the terminal strip being welded or otherwise secured to the end of resistor 34. In some cases the element 46- may be a strip resistor.

Figure 6 shows a large stack of insulator elements 22 with elements 2 3 at the top and bottom, joined by a long strip '40" through the slots 36 and bent over at the top and below the strip 20. The opening 30' between the insulators receives resistors and/ or terminal strips as above described. A rectangular metallic jacket 26' may transfer heat to fluid flowing longitudinally or transversely on the outside of the jacket.

In some cases it may be preferable to insert two of the resistors when the lower insulator elements are assembled and before the middle insulator elements are put in place, and then insert the other two resistors before the top insulator elements are assembled.

Where for any reason an insulator must be disassembled, the ends 44 are bent out straight and the insulator elements can then be removed after withdrawing the clip 40. In this way broken insulator elements can be replaced, and other changes can be made.

In view of my invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of my invention without copying the structure shown, and I, therefore, claim all such insofar as they fall within the reasonable spirit and scope of my claim.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

In an electric heater, an elongated flexible metallic strip having a rectangular fastener slot therethrough which extends lengthwise of the metallic strip, a plurality of ceramic insulators arranged in a stack with adjoining sides engaging, including a top insulator, a bottom insulator and at least one intermediate insulator, said stack of insulators extending transversely of the metallic strip and the bottom insulator engaging the metallic strip, the insulators at their adjoining sides having slots which cooperate to form resistor receiving openings which extend longitudinally of the metallic strip, each of the insulators having in line across the stack a fastener slot of rectangular cross section positioned between the resistor receiving openings, the fastener slots being elongated lengthwise of the metallic strip, and the fastener slots in the stack of insulators being in line with the fastener slot in the metallic strip, the top insulator having on either side of its fastener slot, at the edge remote from the other insulators of the stack, recesses which are progressively tapered as they extend farther away from the fastener slot, and a fastener bar of rectangular cross section having its greatest cross sectional dimension extending longitudinally of the metallic strip, said fastener bar extending through the fastener slots in the stack of insulators and the fastener slot in the metallic strip, the fastener bar having prongs oppositely bent beyond the fastener slot in the metallic strip. and prongs oppositely bent beyond the fastener slot in the top insulator and extending into said tapered recesses, said prongs diverging from one another at acute angles to the fastener bar and engaging in the walls of the recesses and assisting in preventing the insulators from turning, said single fastener bar preventing the insulator stack from turning with respect to the metallic strip.

References Cited in the file of this patent UNITED STATES PATENTS 921,134 Maenche May 11, 1909 1,077,676 Cubitt Nov. 4, 1913 1,079,895 Talbot Nov. 25, 1913 1,677,313 Woodson July 17, 1928 1,680,404 Woodson Aug. 14, 1928 1,883,927 Ipsen et al. Oct. 25, 1932 2,128,058 Shaw Aug. 23, 1938 2,473,264 Stevens et a1. June 14, 1949 2,536,747 Hynes Jan. 2, 1951 2,627,099 Becker Feb. 3, 1953 2,750,487 Hynes June 12, 1956 FOREIGN PATENTS 1,055 Great Britain 1914 893,531 Germany Oct. 15, 1953 708,535 Great Britain May 5, 1954

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