US1494940A

US1494940A - Electric heating unit

Info

Publication number: US1494940A
Application number: US595192A
Authority: US
Inventors: Charles C Abbott
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1922-10-17
Filing date: 1922-10-17
Publication date: 1924-05-20
Anticipated expiration: 1941-05-20
Also published as: FR28249E

Description

May 20, 1924. 1,494,940

C. C. ABBOTT ELECTRIC HEATING UNIT Filed (kit. 17, [922 Im/entoF: Cha ics C. Abbott,

yW M H is Att c nn e Patented May 20, 1924.

I UNITED SQIA-TES,

came s c. ABBOTT, or

rITTSFI'EmJ, MASSACHUSETTS, ASSIGNOB' To GENERAL mncmc COMPANY, COBPQBATION: OF NEW YORK.

nLncTmc HEATING UNIT.

Application filed October 1%, am. serm'm. 595,192.

To all whom it mag ceman:

Be it known that I, CHARLES C. ABBOTT,

a citizen of the United States, 'residin at- Pittsfield, in the county of Berkshire, tate of Massachusetts, have'invented certain new and useful Improvements in Electric Heating Units, of which the following is a specification.

My invention relates to electric heating units particularly to sheath wire heating unit s,.and has for its object the provision of simple, reliable and 'efiicient means for supporting the terminals thereof,

More specifically my invention relates to 1 improvements in sheath wire heating units of the helical core type, disclosed in my filed October 5, 1921, of which this application is a continuation inpart. In heat- 2 ing units of this typethe resistance conof granular insulating material enclosed in a metallic containing sheath. To the ends of the resistance gonductor are secured terminals which project from the sheath. In. the construction of the heating unit, the resistance conductor with the terminals attached is first temporarily secured centrally in the sheath,.for example, bysecuring the outer ends of the terminals. The sheath is then filled with granular insulating material and swaged to compact the insulatin material. I have found that it is advlsable' that meansbe provided for positively centering the inner ends of the terminals in the sheath during the construction of the unit, otherwise the terminals and resistance conductor may be displaced and grounded on the sheath.

In carrying out my invention, I provide insulating members on the inner ends of the terminals for holding theinner ends of the terminals centrally of the sheath.- In one form of my invention these insulating members are shaped as washers, while in a modified formof my invention the insulating members are square.

For a better understanding of my invention reference should be had to the accompanying drawing in which Fig. 1 isg, a view partially in section of an assembled heating unit embodying my invention before the swaging operation; ljig. 2 is a view partially in section. showmg'a comsuch bedded a helical resistance conductor 13' pleted heating unit embodying" my inven- Fig. 3 1s a sectional 'view similar to tion; Fig 1 showing-amodified form of my inventlon; while Fig...4='is a sectional view in the direction of the arrows. Referring to Figs. 1 and 2 of the draw ng, m one form'of my invention the heatmg unit 10 comprises a metallic cylindrica containing sheath 11 which is filled with a suitable granular insulating material 12, as magnesium oxide, inwhich is im-- taken along'the line 4'-4 of Fig. 3, looking having a terminal 14 secured to eachend. The inner end of each terminal 14 is pro-.

v vided with a threadedportion 15 on which copending application, Serial No. 505,588,.

is securedthe resistance conductor 13 and also aninsulating spacing member 16 made of a suitable insulating material, such as mical. In the assembly'of the heating unit, duc'tor is imbedded in a compacted mass a spacing member 16, shown in the form of a washer, is screwed on the threaded portion 15 of each terminal, and the terminals then secured to the ends of the helical resistance conductor by screwing their threaded ends into the convolutions of the resistance conductor as described and claimed in my copendin application, Serial No. 549,636, filed pril 4, 1922. Preferably the terminals are screwed into the turns of the resistance conductor until the latter engages the spacing washers.

The resistance conductor 13 with the ter minals 14 attached is then inserted in the sheath 11, the resistance conductor stretched to separate its turns, and the terminals secured against the longitudinal pull of the resistance conductor by means of washers 17, only one of which is shown, placed on the terminals and seated in the ends of the' sheath, which ends are counterbored to receive them, and a suitable clip 18 secured on each terminal so as to bear against the corresponding washer 17. One of the washers 17, for example the left-hand one, as shown,-is in the form of a star washer. The insulating spacing washers 16 on the inner ends of the terminal fit loosely in the sheath 11 and serve the, purpose of holding the inner ends of the terminals substantially central in the sheath, the

outer ends of the terminals being centered in the sheath by the washer 17. i

'In the next step in the construction of-the i unit the granular insulating material .ings' inthe star washer 17, the s he d 12 is filled in the sheath 11 through the, openeath being in a vertical position withv the star washer uppermost and vibrated so as to shake the insulating material -dbwn past the spacing .washers 16, which fit the sheath loosely enough to permit the insulating material to pass, and between the turns of the tends to'compact. the insulating material. After the sheath has been filled with the powdered insulating materialit is closed by means of a solid washer 17', which is inserted in the sheath'over the star ,washera'nd clip 18, and the ends of the sheath bent or pinched over at intervals 19 so asto secure the Washers at each endin place. The heating unit has now been assembled as shown in Fig. 1. r .M'The granular insulating material 12 1s next compacted to a hard dense mass by reducingtlrwdiamet'epotii sheath by sv vaging, after which the ends of the sheath are cut off to efi'ect the removal of the

washers

17 and 17 and expose the ends of terminals 14, and connecting lugs 20 of a suitable material, such as brass, secured to .the terminals. These connecting lugs may be secured as described and claimed in my aforesaid copending application, Serial No.549,636 by providing nicks 21 in the outer ends of the terminals, inserting the nicked ends in suitable recesses in\ the lugs 20 and then compressing the material of the lugs laterally into the nicks. Insulating washers 22 may be placed over the'ends of the'sheath against which central in the sheath vby the spacing washer 16 during both the filling and swagingmpera-tions. As a result the powdered insulating material 12 is distributed and com acted uniformly around the terminals where y the The spacing block 16 is of such size that its corners engage with the inner surface of the sheath 11, as shown in Fig. 4. Ample 7 space is thus provided around the flat sides of the blocks for the insulating material to befilled past the blocks into all parts of the sheath. The method of manufacture of this understood with reference to the description ofFlgs. 1 and 2. During the swaging operation the lava'block may cru nble and become a part of the giahular insulating material.

ductor are thus effectively centered in the .sheath so that the insulating material is compacted uniformly around them.

i It will be observed that by means of the square spacing members the inner ends of Y Iing members shown in Figs. 1 and 2, since the round spacing members must be sufli- "resistance conductor. This vibration also modified form ofmy invention will be The terminals and resistance con- 39 ciently loose to permit the granular insulat- .90

ing material to be filled past them into the sheath. I .have found that lava. is a material which is particularly adaptedfor the spacing members. Spacing members made of lava do not have the tendency to break up 01" flake oif during the vibration of the unit when insulating material is being filled in, which tendency is characteristic of the mica spacing members.

- While'I have described my invention as 10 embodied in concrete form and as operating in aspecific manner in accordance with the provislons of the patent statutes, it should be understood that I do not limit my invention thereto, since various modifications 1 thereof will suggest themselves to those skilled in the art without. departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

What I claim as new and desire to secure byLetters Patent of the United States, is 1. An electric heating unit comprising a sheath, compacted granular insulating material in said sheath, a resistance conductor terminals are thoroughly insulated fromthe embedded and supported in said insulat- 7 terminal by providing a flattened portion 23 in theterminal near the threaded portion 15. The spaci block is seated against the shoulders 23 formed by this flattened] poring material, a terminal for saidresistance conductor embedded and supported in said insulating material, and an insulating member for centering said terminal in said sheath while the insulating material is put 190 in and compacted to secure said terminal.

2. An electric heating unit comprising a heath, compacted insulating imaterial in said sheath, a resistance conductor embedded in said insulating material, terminals for said resistance conductor embedded in said insulating material projecting from the ends of said sheath, and insulating spacing members on the inner ends of said terminals for holding the resistance conductor and terminals central of said sheath while the insulating material is put in and compacted to secure them.

3. An electric heating unit comprising a sheath, granular insulating material in said sheath compacted by swaging to a hard and dense mass, a resistance conductor embedded in said insulating material, terminals for said resistance conductor embedded in said insulating material, and insulating spacing members'on the inner ends of'said terminals for holding the resistance conductor and terminals central of said sheath while the insulating material is put in and compacted by swaging the sheathwhereby the resistance conductor and terminals are secured. I

4. An electric heating, unit comprising a. sheath, compacted granular insulating materialin said sheath, a resistance conductorembedded in sa'id insulating material, terminals. for said 'resistance conductor embedded in said insulating material, and insulating spacing members on the inner ends of said terminals for holding the resistance conductor and terminals central of the sheath while the insulating material is put in and compacted, said spacing members being adapted to permit 'said insulating ma terialbeing filled into said sheath.

5. An electric heating unit comprising a cylindrical sheath, compacted-granular insulating material in saidsheath, a resistance conductor embedded in said insulating material, terminals for said resistance conductor embedded in said insulating material, and non-circular insulating spacing members-0n the inner ends of said terminals for holding the resistance conductor and the inner ends of said terminals central while the insulating-material is put in the sheath and compacted.

6. An electric heating unit comprising a cylindrical sheath, com acted granular insulating material in sai sheath, a resistance conductor embedded and supported in said insulating material, terminals for said resistance conductorembedded and supported in said insulating material, and insulating spacing members on the inner ends of said terminals for holding the resistance conductor and terminals central of the sheath while the insulating material is put in and compacted, said spacing members being provided with flat sides past which said insulating material may be filled into said sheath.

7. An electric heating unit comprising a sheath, compacted granular insulating material in said sheath, a resistance-conductor embedded in said insulating material, terminals for 7 said' resistance conductor embedded in said .insulating material, and square insulating spacing members secured to the inner ends of said terminals for holding the resistance conductor and terminals central of the sheath while the sheath is being filled with the insulating material and swaged to compact it.

8. An electric heating unit comprising a sheath, compacted granular insulating material in said sheath, a helical resistance conductor embedded in said insulating material, terminals for said resistance conductor embedded in said insulating material having threaded portions on which the ends of said resistance conductor are screwed so as to be secured thereto, flattened portions forming shoulders on said terminals adjacent said threaded portions, and insulating s acing members secured on said terminals etween said shoulders and the ends of said resistance conductor for holding the resistance conductor and terminals central of the sheath while the insulating material is put in and compacted whereby the resistance conductor and terminals are secured.

'In witness whereof, I have hereunto set my hand this 13th day ofOctober, 1922.

CHARLES E, ABBOTT.