US2602130A - Electrical heating element - Google Patents

Description

July,1, 1952 H. N. SHAW 2,602,130

ELECTRICAL HEATING ELEMENT v Filed Sept. 2s, 1950 IN VEN TOR. add 7 Patented July 1, 1952 UNITED STATES PATENT OFFICE Harold N. Shaw,:Erie, Pa.

Application September 26, 1950, Serial No. 186,733

This invention relates to improvements in electrical heating elements and more particularly to the type of heating elements shown in my Patents Nos. 2,217,296 and 2,265,549.

In thepatents above referred to electrical heating elements of both helical and flat conformation are disclosed, each of which is adapted for use in a particular application. The helical struc ture shown in Fig. 12 of my Patent 2,265,549, while very satisfactory in use, has nevertheless required a relatively large amount of labor in the assembly thereof rendering the unit relatively expensive. The simpler construction shown in Fig. 19 of my Patent 2,217,296 is less expensive to manufacture, but this construction is not entirely satisfactory when used for elements of small diameter because in the smaller sizes there is danger of short circuiting through the supporting channels due to the small clearances permitted. With respect to the 'fiattype of element shown in Figs. 20m 21 of my Patent 2,217,296 the channel shaped clips I i, being relatively'ex pensiva'also make the cost Tof jconstruction of this unit higher than is desired. .1

" With the'above in mindg'a principal object of the present invention is to provide} an improved" helical heating element having relatively few in-'- sulators to" thereby reduce. the bulk of the unit as well as the cost thereof. Q f

A further object of the invention is to provide an improved helical heating element having in sulators of improved construction mounted on an improved axially extending supporting member, said insulators and supporting member being so constructed that positive clearance between th element and supporting member is at alltimes provided. g i

A furthenmore specific object of the invention is to provide an improved helical heating element of the class described, wherein the axially extending supporting member isformed with a: plurality of radially projecting, longitudinally extending flanges on which the improved insulators are mounted, said insulators being slotted at their inner ends to receive said flanges.

A further object of the invention is to provide animproved helical heating element of the classdescribed having a pair oflinsulating end blocks, w c b oc ed-.xwithm ell extending slots to .permit theendeiportions "of them! p g m ber to p oj t th re h oush, e ntire unit beingheld in. assembled condition by bending over the flan fis, pf the supportingmem \ber: at the ends thereof outwardly of said end block slots. 7 I 1 14 Claims. (01. 2o174) A further object of the invention i to provide an improved flat type of electrical heating element having insulators of similar construction to the insulators used on the helical elements, said insulators being held in assembled condition by an inexpensive clip made of wire.

A further object of the invention is to provide improved electrical heating elements of the class described which are light in weight, which are constructedso as not to store appreciable amounts of heat, and which are therefore capable of relatively fast action both in heating up and in cooling off. V

A further object of the invention is to provide improved heating elements which are inexpensive in construction, not only because of the use of inexpensive materials. but also because the im proved construction readily adapts itself to mass production methods.

With the above and other objects in view, the invention consists of the improved electrical heating elements, and all of their parts and combinations, as set forth in the claims and all equivalents thereof.

In the drawing accompanying and forming a part of this specification, wherein are shown two embodiments of the invention, and wherein like characters of reference indicate the same parts in all of the views:

Fig. 1 is a fragmentary side elevational view of an improved helical heating element embodying the principles of the invention; ":Fig.'2 is a'left hand end elevational view of the element shownin Fig. 1;

Fig. 3 is a'right hand end elevational view of the element shown in Fig. l;

Fig. 4 is a transverse vertical sectional view taken approximately along the line 4-4 of Fig. 1;

Y Fig. 5 is an enlarged perspectiveview of one of the insulators embodied in the improved helical heating element;

Fig. 6- is a fragmentary side elevational view of a flat type electrical heating element embodying the principles of the invention, one of the wire clips being removed and parts of said,

elementlbeing broken away;

Fig. 'Iis a transverse vertical sectional view taken approximately along the line 1-1 of Fig,- 6; Fig. 8 is aside elevational view: showing the wire clip removed from the-element .shown in Fig.6; I 1 I I Fig. 9. is.a perspective view of one of the in:

heating element shown in Fig. 6; e v v k Fig. l0 is a side elevational viewof-a modie sulators embodied in the improved electrical v v fled form of clip adapted for use with the improved heating element shown in Fig. 6; and

Fig. 11 is a transverse sectional plan view taken along the line IIII of Fig. 10, one of the insulators with which the clip is adapted to be associated being shown in dot and dash lines.

Referring more particularly to Figs. 1 to of the drawing, the numeral I5 indicates an elongated supporting member or spider, preferably formed of thin metal and having a plurality of radially projecting longitudinal flanges I6, I! and IS. The preferred form of spider I5 is Y-shaped in cross section and may be formed of two pieces of metal V-shaped in cross section and spot welded together as shown. At one end of the spider an electrical connection member I9 is formed integral therewith, said member projecting axially from the end of the spider.

A helix 20 of channel shaped metal of the type having metallurgical qualities commonly present in electrical heating elements surrounds the supporting member or spider I5 so that the latter extends coaxially within the helix 20. A plurality of insulators 2| are mounted on the supporting member I5 and arepositioned between adjacent turns of the helix 20. The insulators 2| project radially inwardly from between the turns of the helix 20- and are each formed with an enlarged inner end 22 which overlaps the adjacent turns of the helix 20 and which is formed with a slot 23 for receiving one of the flanges of the supporting member or spider I5, as shown. As also shown in the drawing, all of the insulators mounted on one of the flanges of the spider I5 are in longitudinal alignment. The insulators 2! are formed with enlarged outer ends 24 which also overlap adjacent turns of the helix 2!] and which project radially outwardly from the helix 20 a predetermined distance. The enlarged outer portions of adjacent insulators on aflange of the spider I5 may abut each, other as may the enlarged inner portions 22. I

An electrical connection member 25 is fixed to the end of the helix 20 adjacent the connection member I9. An insulating end-block 26, preferably cylindrical in form and having a radius substantially equal to the radial" distance from the axis of the spider to the outer tips of the insulators; is formed with. a central aperture 21 and preferably withthree slots 28 extending radially outwardly from the aperture 21. The block 26 is also formed with a rectangular ape'r ture 29 therethrough. The end of the. supporting member or spider I SadjacentJth'e connectors I9 and 25 projects through the aperture 21 and slots 28 as shown in Fig. 3. The connector 25 projects'through the aperture 29. The block' 26 is preferably formed with a circular recess 39 in its outer end face; said recess having a radius which is preferably equal to the radius of the slots 28, and said recess also communicating with the aperture 29. "The end block 26 abuts the adjacent end of the helix 20', and the ends of the flanges I6, I! and IB are bent over within the recess 30 as shown in Fig. 3130, prevent movement of said block away from the helix 20.

Ametal connection member 3I connects the left hand-end of thehelix 20 (as viewed; in Fig. 1') with the adjacent end of the spider' I5. An insulating end'block'32, preferably identical with the end block 26, is mounted on the end of the spider'I5 oppositethe block 26.1 The adjacent ends of flanges I6, I1 and I8 project-through the block 32 and into the endf-recessthereof, said ends of said flanges'bingbentover, as 'shownln 4 Fig. 2, to prevent outward movement of the block 32. The block 32 preferably abuts the adjacent end of the helix 20.

The blocks 26 and 32 may be formed with suitable radially extending bosses 33 and 34 to provide means for conforming the abutting surfaces of said end blocks to the curvature of the helix 20. Each of the end blocks 26 and 32 is also preferably formed with a recess 35 (see Fig. 4) for receiving one end of the helix 20, the recess 35 and the bosses 34 and 33 cooperating to provide the end blocks 26 and 32 with means for conforming to the shape of the end of the helix 29.

It will be apparent from the drawing that the improved helical heating element is adapted to be positioned in a metal tube and that all metal portions of said element will be completely insulated from the side and end walls of said tube. Itis also apparent that the improved insulators 2| and the improved spider I5 coact to provide positive clearance between said spider and the helix 29 with the result that short circuiting between the helix and the spider is positively prevented even when the improved heating element is made in a small size.

The improved spider I5, while being light in weight, is inherently'strong, and its lack of bulk preventsit from storing up appreciable quantities ofheat. Thefree radiation of heat from the helix 29 which is permitted by the improved construction, combined with the lack of bulk in the spider and in the insulators, provides for very quick heating and coolingof the helix. While the im-- proved spider I5 is shown as having three radially projecting longitudinal flanges, it is obvious that it is within the concept of the invention to provide a spider having radial flanges other than three in number in order tosuit requirements; Referring to Figssfi and 7, the improved flat form of the invention comprises an elongated extent of channel shaped metal; preferably having thesame metallurgical characteristics-as the helix 20 ofthe form of the invention shown in Fig. 1. The extent 36' is arrange'dwith reverse bends 3], as shown in :Fig. 6'," Ithechannel's' being compressed as illustrated to 'ernfiitthe formation ofsaid reverse bends. A plurality .of improved insulators 38 are positioned in the spaces 39.between adjacent extents of the channel 39 'andare alignedin rows as shown. ,7 V V, v

Referring to Fig.9 the insulators 38 are in the general form of a rectangular block havingfpar allel end walls .4I, parallel side walls 40, and parallel top andbottom walls 42. The insulators 38 are preferably formed in each of their top and bottom wall 42 with a central transversely extending groove .43. The side walls oft-he grooves 43 diverge outwardly ateach end as shown at 44. The insulators 38 are also formed in each of: their opposite end walls H with a central, vertically extending groove 45. The depth of the grooves 43 is preferably slightly less than half of the width of the-channel 36, the'reason for. which will be pointed out hereinafter; 1 J 1 As shown in Figs. 6 and 7,:when the insulators 38 are in aligned position,- t'he to'p wall of one insulatorisin-abutment with the bottom WaZHOf the insulator thereabove. The' insulators 38 are preferably-held in alignment by thense ofis'pring wire clips- 46 0f generally- LI -shaped h'onformation, the legs' 'of 'said clips being positionable in the grooves 45 of the aligned insulators; as shown in Figs. Sand 7'. Since the channel 36 is slightly wider than the space provided by a pair of regis 5 tering grooves 43 in adjacent insulators 38, the wire clips 46, in pulling the insulators 38 together, compress thechannel transversely where said channel passes through said grooves. This prevents the rows of insulators from moving longitudinally of the channels, and thus the insulator are secured in their proper spaced relationship. Figs. and 11 illustrate a modified form of clip 41 which may be used in lieu of the clip 46 of Figs. 6 to 8. The clip 41 may have its leg portions 48 and 49 formed of material which is T-shaped in cross section, the leg 48 having an inwardly projecting flange 50 and the leg 49 having an inwardly projecting flange 5|. As shown in Fig. 11, the clip 41 is adapted to be positioned around a row of insulators with'the flanges 50 and 5| positioned in the grooves 45 of said insulators, the remainder of the leg portions 48 and 49 being adapted to contact the end walls 4| of the insulators to provide additional support.

The structure of the form of the invention illustrated in Figs. 6 to 10 insures positive clearance between the channel 36 and the wire clips 46 or 41, in much the same manner that the structure of the form of the invention shown in Figs. 1 to 4 insures positive clearance between the spider l5 and the helix 20. The divergent conformation of the ends of the grooves 43 of the insulators 38 insures maximum radiation of heat from the channel 36, and the simple construction of the clips 46 and 41 not only reduces the cost, but also reduces the bulk of the unit. As previously stated, any reduction in the bulk of a heating unit of this type lowers the ability of the element to store heat and correspondingly increases the speed with which the element can heat up or cool down.

While, only a few forms of the invention have been shown. and described, it is obvious that variousother changes and modifications may be made Without departing from the spirit of the invention, and all of such changes arecontemplated as may come within the scope of the claims.

,. What I claim as new is: U

l.' In an electric heating unit: an element formed of an elongated continuous extent of metal arranged in circuitous form; insulating members carried at intervals by the element between side portions thereof, each of said insulating members having opposite ends overlapping adjacent element portions said insulating members extending in rows with the overlapping end portion of one member projecting toward the overlapping end portion of an adjacent insulating member to retain the element therebetween, one of said ends of each of the insulating members being formed with a slot; and a supporting memher-encircling said insulating members and holding said insulating members and said element in assembled condition, said supporting member having portions positioned in the slots of said insulating members.

2. In an electric heating unit: an element .formed of an elongated continuous extent of metal arranged in circuitous form; insulating zmembers carried at intervals by the element between side portions thereof, said insulating members'having opposite ends overlapping adjacent element portions and projecting beyond the sides thereof, said projecting ends of the insulating 1=members each being formed with a slot; and a supporting member generally T-shaped in cross section encircling said holding said insulating members and insulating members and said element in assembled condition, said T-shaped cross jecting. end being: slotted projecting jradially outwardly 6 section including a flange positioned in the slots of said insulating members. v 7

3. In an electric heating unit: anll e lment formed of an elongated continuous, extent er metal arranged. in circuitous form-j. insulating members carried, at intervalsloy. the 'elementbetween side portions thereotsaid insulating'members having opposite endsoverlapping adjacent element portions and projecting beyondlthe sides thereof, said projecting ends oi the insulating members each-being rormed with a slot; and a wire encirclingsaid insulatingmembers and holding said insulating members and said elementin assembled condition, said wire beinglaccommo dated in the slots of said insulating members.

4. In an electrical heating unit: an elongated helix of metal; an elongated supportingmember extending axially within said helix, saidmember being formedwitha plurality ,of radially projectf ing longitudinally extending flanges; and a plurality of insulating members positioned between adjacent turns of saidhelix, said insulating members each having an enlarged end projecting radially inwardly from said helix and overlapping adjacent turns oflsaid-he lix, said inwardlyfjpriojecting end being slotted to receive one of the flanges of said elongated supporting member, and said insulating members having enlarged ends projecting radially outwardly from the helix and overlapping adjacent turns, with ends of said overlapping portions of vinsulating members which are on opposite sides of a turn projecting toward one another. d,

5. In an electrical heatingunit: an elongated helix of metal; an elongated supporting member extending axially within said helix, said'member being formed. with a plurality of radially projecting longitudinally extending flangesaa p111- rality of insulating members positioned between adjacent turns of said helix, said insulating members each having an enlarged end projecting radially inwardly from said helix and overlapping adjacent turns of said helix, said inwardly proto receive e 91t flanges of.,said elongated supporting member, and said insulating members having enlarged-ends from --the.helix and overlapping adjacent turns, with ends of said overlapping portions of insulating members which are on opposite sidesof a turn projecting toward one another, and. a pair of endblocks made of electrical insulating material. each. of said end blocks being formed with radial slots to permit projection therethrough of an end portion of said elongated supporting memberzay 6. In an electrical heating unit: an elongated helix of metal; an elongated supporting member extending axially withinsaid -helix,-s-aid-imember being iormed witha plur'alityof radially'projecting longitudinally extending flanges; a plurality "of insulating members positioned between adjacent turns of said helix, said insulating members each having an enlarged endpro ecting radially inwardly from said helix andove'rlapp'ing adjacent turns'of said helix, saidinwardly projectingend] being slotted to rece veone] of 'the flanges of said. elongated supporting member, and said'ins'ulating" members having enlarged ends and are on opposite sides of a turn projecting toward one anothenand a pair of end blocks'made'of electrical insulating. mater m each pi sa d end blocks being formed with radial slots to permit projection therethrough of an end portion of said elongated supporting member; the flanges atthe ends of said supporting member outwardly of said'end block slots being bent over-to preventremoval of said: end blocks and to hold the unit in assembled condition.

'7". In an electrical heating unit: an elongated helix of metal; an elongated supporting member extending. axially within saidhelix, said member beingformed with a plurality of radially project in}; longitudinally extending" flanges; aplurality of insulating members positioned between adjacent. turns-of said helix, saidinsulating members each having an enlarged endprojecting radi'ally'lnwardlyfrom said helix and" overlapping adjacent turns of said helix, said inwardly projecting end being slotted to receive one-of the flanges or saidelongated. supporting member, and said, insulating. members having enlarged ends projecting radially outwardly from the helix and overlapping adjacent turns, "with ends of said overlapping portions of insulating members which are-on opposite sides of a turn projecting toward one another, and a pair of end blocks made of electrical insulating material each of said end blocks being formed with radial slots to permit" projection therethrough of an end portion of said elongated supporting member, the

flanges at the ends of said supporting member outwardly of said end block slots being bent over toprevent removal of said end blocks and to hold the unit in assembled condition, and one of said end blocks being formed with an outwardly facing recess in its. outerend' face for accom-modating the adjacentend of said supporting member inwardly of the outer face of said end block.

" 8i In anelectricalheating unit: an elongated helix of metal; an elongated metallic supporting member extending axially within saidhelix, said member being formed with a plurality of radially projecting longitudinally extending flanges; a plurality of insulating members positioned between adjacent turns of'sai'd helix, said insulating members each having an: enlarged" end projecting radially inwardly from said helix and overlapping adj acent turns of said. helix said inwardly projecting end being. slotted to receive one of theflanges of'said elongated supportingrmemher; an electricalconnection member on one end of said supporting; member; an electrical connection member on. the adjacent end of said helix;

and" an. electrical connection between said helix and said. supporting, member at the opposite end of the. unit;

9'. In an; electrical heating unit: an elongated helix of metal; an elongated supporting member extending axially within said helix, said member being formed witlra plurality of radially projecting; longitudinally extending flanges; a plurality of insulating members positioned" between adjacent turnsot said-helix, said insulating members each. having an enlarged end projecting radially inwardly from saidhel-ixandoverlapping adjacent turns of said helix said. inwardly projecting end being; slottedto. receive one of the flanges of said elongated, supporting member; ands'ai'd insulating members eachhaving ajportion'projecting radially outwardly or said? h'el'ix andoverlapping ad'jacent turns of said helix, adjacent insulating members on Opposite sides of" the same turn of said'hell'x having their inwardly and outwardly overlapping portions abutting;and a pair'of end blocks 'made. of electricalinsulating material, each of said end" blocks being formed with radial 8 slots to permit projection therethrough of'an end portion of said elongated supporting member.

10. In an electrical heating unit: an elongated helix of metal; an elongated metallic supporting member extending axiallywithin said helix, said member being formed with a plurality of radially projecting longitudinally extending flanges; a plurality of insulating members positioned between adjacent turns of said helix, said insulating members each having an enlarged end projecting' radially inwardly from said helix and overlapping adjacent turns of' said helix, said inwardly projecting end being slotted to receive one of the flanges of said elongated supporting member; a pair of end blocks made of electrical insulating material, each of said end blocks being formed with radial slots to permit projection therethrough of an end portion of said elongated supporting member; a first electrical connection member on one end of said supporting member outwardly of the adjacent end block; a second electrical connection member on the helixat said end, the adjacent end block being'formed with an opening to permit said second connection member to pass therethrough; and an electrical connection between said supporting member and said helix at the opposite end of the unit.

1'1. In an electrical heating unit: an elongated helix of metal; anelongated supporting'member extending axially within said helix, said member being formed with a plurality of radially project'- ing. longitudinally extending flanges; a plurality of insulating members positioned between ad jacent turns of said helix, said insulating members each having an enlarged end projecting radially inwardly from said helix and overlapping adjacent turns of said helix, said inwardly projecting end being slotted to receive one of the flanges of'said elongated supporting member, and said, insulating members each having a portion projecting radially outwardly of said helix a predetermined distance, adjacent insulating members which are on opposite sides of the same turn of the helix having portions projecting toward one another to retain the helix; and a pair of circular end'blocks made of electrical insulating material, each of said end blocks beingformed with radial slots to permit projection therethrough of an end portion of said elongatedsupporting member, and said end blocks being of such size that the peripheries thereof are spaced radially outwardly from said helix the same dis came as the outer ends of said insulating members.

12; In an electrical heating unit: an elongated helix of metal; an elongated supporting member extending axially within said helix, said member being formed with a plurality of radially proj'ecting longitudinally extending flanges; a plurality of insulating members positioned between adjacent turns of said helix, said insulating members each having an enlarged end projecting radially inwardly from said helix and overlapping adjacent turns of said helix, said inwardly projecting end being slotted to receive one of the fiangesof said elongated supporting member, and

said insulating members each having a portion projecting radiallyoutwardly of said helix a predetermined dlstance; said outwardly projecting portions overlapping adjacent turns of said helix and adjacent insulating members extending in rows longitudinally of the helix and'havi'ng ends of their overlapping: portions abutting onv both sides 01 the helix; andla pair of circular end blocks made ofele'c'tri'cal insulating material,

each of said end blocks being formed with radial slots to permit projection therethrough of an end portion of said elongated supporting member, and said end blocks being of such size that the peripheries thereof are spaced radially outwardly from said helix the same distance as the outer ends of said insulating members.

13. In an electric heating unit: an element formed of an elongated continuous extent of metal arranged in circuitous form, individual insulating members carried at intervals in the circuitous extent of the element between side portions thereof, each of said insulating members having its ends overlapping adjacent element portions, said individual insulating members extending in rows with the overlappin end portions of one member projecting toward the overlapping end portions of an adjacent insulating member in the row to retain the element therebetween, at least one of the ends of each insulating member being formed with a slot, and a supporting member having a portion positioned in the slots of said insulating members to hold the latter and the element in assembled condition.

14. In an electric heating unit, an element formed of an elongated continuous channelshaped ribbon arranged in circuitous form, insu- 10 lating members carried at intervals by the element between the turns thereof, said insulating members having projecting portions at both ends which overlap opposite sides of adjacent element portions, said projecting portions at at least one of said ends of the insulators having a slot extending at right angles to the element turns, and a member extending along and engaging said slots to hold the insulators in assembled condi- HAROLD N. SHAW.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,706,014 Whittingham Mar. 19, 1929 2,217,296 Shaw Oct. 8, 1940 2,265,549 Shaw Dec. 9, 1941 FOREIGN PATENTS Number Country Date 235,993 Great Britain July 2, 1925 411,162 Great Britai June 4, 1934

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