US1828635A - Electric heater - Google Patents

Description

Oct. 20, 1931. c. c, ABBOTT 1,828,635

ELECTRI C HEATER Filed April 29, 1929 Inventor: Charles C. AbbOt't,

His Attorney.

Patented Oct. 20, 1931 UNITED STATES PATENT. oF lcE cannon. or rrrrsrman, msa cnusn'rrs, ASSIGNOB r GENERAL ELEG- 'rmc comm, a conrona'rron or mew Yoax ELEGI'BIC imam Application filed April as, 1929. Serial llo. averse.

My invention relates to electric heaters and has for its object the provision of a simple,

eflicient and inexpensive electric heater and method of making it.

L Although it obviously has other applications, my invention is particularly use connection with electric heaters provided for relatively low temperature work. More specifically, my invention is particularly useful in connection with electric. heaters employed to heat the lubricating oil of refrigerator apparatus.

In carrying my invention into effect in one form thereof, I provide a heating unit which comprises a supporting member upon which the resistance conductor is wound. Preferably, the supporting member will be formed from a suitable heat resistant material, such as asbestos. Each end of the resistance unit will be secured to a suitable lead by means of a terminal member which will be compressed, as by a swagin operation, about a portion of the turns of t e coiled resistance conductor and the end ortion of the lead. An electrically insulating sheath is provided to house the heating unit. Preferably, the sheath will be provided with a passageway shaped so that the heating unit when positioned within the sheath will have a substantially hairpin shape. Thus, in the finished electric heater,

. the heating unit carrym the terminals are adjacent each other. Odiviously, however, the heater may be formed in any suitable as shape. Thus, the sheath may be substantially straight with the leads projecting from the opposite ends.

For a more complete understanding of my invention, reference should be had to the 40 accompanying drawings in which Fig. 1 is an elevation partly in section of an electric heater embodying my invention, and Fig. 2 is a part sectional view illustrating themanner in which one end of the resistance conductor is connected to its lead, the view beingktaken to a larger scale than Fig. 1.

eferring to the drawings, I have shown my invention in connection with an electric heater comprising a heating unit 10 which is provided with an electrically insulating v ulin the end portions of sheath or housing 11 and a pair of leads 12. It will be understood that m service these leads will serve to connect the heating unit with a suitable source of electrical supply, (not shown).

As shown, the heating unit 10 comprises an electrical resistance conductor or wire 14, which will be wound or coiled upon a suitable supporting member or core 15. Preferably, this supporting member will be madeof a so suitable heat insulating, flexible and slightly yielding material such as asbestos. A flexible and yielding asbestos cord may be used conveniently for the supporting member.

Thus, the resistance conductor may be wound 66 continuously upon a relatively long length of the asbestos cord, after which the cord with the conductor wound thereon may be cut into portions of the required lengths for the heatmg units.

The provision of the heat resistant, flexible supporting member 15 is an important feature of my invention. It will be appreciated that in an electric heater adapted for low temgerature work, it is desirable to use a very 76 neresistance conductor in order to secure the required resistance. In order to use satisfaetorily a very fine resistance conductor, I." have provided the conductor with a heat resistantcore which serves both to support so the turns of'the resistance conductor and to retain the various turns in their proper spaced relation. It will be observed that since the conductor is provided with a support which is slightly yielding, the conductor as it is 35 being wound will slightly depress the outer surface of the support so that each turn of I the conductor will form its own recess. By reason of this construction any displacement of the'turns is prevented. It will e understood, however,,that the asbestos supporting member'15 is sufiiciently hard to provide a com aratively stron and firm support for the 'ght conductor, 1t being yielding mere- 1y to the extent of ermitting the resistance 96 conductor to slight depress its outersurface. In other wor s, the, sup orting member 15 will be one possessing su stantlal mechanical strength.

Each end of the heating unit will be suit- 100 till 2 saaose ably connected with its lead member 12. In order to secure the end portion of the resistance conductor to its lead 12 in good mechanical and electrical relation therewith, 1 provide suitable terminal members 16. As shown (Fig. 2), each terminal member 16 is tubular in form and is provided with a stepped bore, one portion 16a of which will serve to receive the end or" the supporting member upon which the resistance conductor is coiled while the other portions 166 and 160 of which will serve to receive the terminal end of the cooperating lead 12.

in assembling the terminal, it will be understood that the end of the support 15 will be inserted in the larger bore 16a of the terminal 16. The second step in assembling the terminal is to slightly compress or crimp the receiving or inner edge of the terminal. 'lhis insures that the terminal will be held in proper position with respect to the coiled resistance conductor during the subsequent swaging operation. Then the end portion of the lead 12'which, of course, will have been bared of its insulation 12a will be inserted in the smaller portions 16?) and 160 of the here. The terminal member 16 will then be subjected to a swaging or like process whereby its diameter will be reduced to such an extent that the terminal will be compressed into firm mechanical and good electrical contact with the end turns of the coiled resist ance unit and the bared end portion or the lead 12. it will be observed, by reference to Fig. 2, that the terminal will be compressed about the end turns of the coiled conductor so that they will be depressed into the yielding surface of the asbestos support. As a matter of fact, it is preferable that the diameter of the asbestos supporting member itself be slightly reduced by the compressed terminal. It also will be observed that the smallest portion 160 of the bore will be compressed tightly about the bared lead while the end of the lead will be received in the slightly larger portion 16b of the bore, Thus, the extreme end portion of the lead will form a head which together with the compressed portion 160 of the terminal will practically prevent thelead from being pulled out. It will be understood that if it is desired, the terminal member 16 may be swaged to such an extent that its outer diameter will be substantially that of the outside diameter hi the coiled conductor. Preferably, and as shown, the resistance end of the terminal will be rounded or hell mouthed so as to prevent injury to the resistance conductor during the swaging operation.

After both oi the leads have been connected to the resistance conductor in the manner just described, the conductor is bent or otherwise shaped in the form or a hairpin so that in the finished heating unit the (Fig. 1).

As has been pointed out, the heating unit will be provided with a suitable electrically insulating sheath or housing l1. Preferably, this sheath will be made of a suitable ceramic compound such as porcelain. In order to adapt the porcelain sheath for a ready assembly with the hairpin shaped heating unit, 1 provide the porcelain sheath with a pair'of substantially parallelspaced passageways 11a and 11b, and on one end with a recess 110 into which the passageways open. As shown, the passageways extend from this recess longitudinally through the sheath to its opposite end where they open to the ex- Ierior of the sheath. In assembling the heating unit with the sheath, the heating unit will be drawn through the passageways 11a and lib, respectively, so that the leg portions a and 10?) will be received in the parallel passageways while the bent or U-shaped portion of the heating unit will be received in therecess llc. it will be observed that in the assembled heater the leads '12 will be projected from the open ends of the passageways. Preferably, before the heating unit is positioned within the sheath, it will be dipped in a suitable liquid cement such as liquid porcelain cement. It will be understood that the entire heating unit including the terminal portions will be dipped in the liquid cement. T his cement when hardened serves to anchor the windings and terminals within the sheath. Thus, in the event the asbestos support becomes charred or weakened by reason of excessively high temperatures, the turns of the wound conductor and likewise the terminals will be held in place.

After the heating unit has been assembled with its sheath 11, the recess 110 will be completely filled with a suitable liquid cement, such'as liquid porcelain cementi After the recess has thus been filled, the heater will be placed into an oven and heated to a suitable temperature and for a suitable length of time so that the entire sheath casing will be dried until it becomes a hard porcelain mass.

It will be observed that I have formed an electric heater which not only will be mechanically strong and durable, but also will be of a comparatively inexpensive construction. The fine resistance conductor is rigidly supported upon the comparatively rigid core member while the leads 12 will be efi'ectively secured both mechanically and electrically with the resistance conductor. The asbestos support 15 will withstand relatively high temperatures without danger of'deterioration or destruction.

It is to be noted that while I have described my invention specifically with reference to a heating unit adapted to low temperature work, the invention is equally useful in connection with high temperature heating units.

terminals are adjacent each other What I claim as new and desire to secure by Letters Patent of the United States is: Y 1. A heating unit comprising a supporting member, a resistance conductor wound upon said supporting member and a terminal member compressed about a portion of saidsupportingmember in contact with the conductor turns wound upon said portion.

2. A heating unit comprising a yielding supporting member, a resistance conductor wound upon said supporting member anda terminal member compressed about said yielding supporting member so as to be in electrical contact w1th a ortion of the turns of said coiled conductor.

3. A heating unit comprising a heat resistant supporting member, a'resistance conductor wound upon said supporting member, a lead for said resistance conductor and an electrical conducting member compressed about a portion of the turns of said wound conductor and about a portion of said lead whereby said lead is secured to said resistance conductor.

4. An electrical heater comprising a heating unit having a yielding supporting memher, a resistance conductor colled about said tion of said lead:

supporting'membema lead for said resistance conductor and means for electrically connecting said resistance conductor and said lead comprising a tubular member compressed about a portion of the turns of said coiled-resistance conductor and an end porcontact with an end portionof said coiled resistance conductor, said tubular terminal member being compressed about the. adjacent end of said lea whereby the-lead is secured to said resistance conductor.

- ance conductor wound upon sa1 7. A heating unit comprising a substantially cylindrical asbestos sup ort, a resistsupport substantially to one end thereof, a lead for said resistance conductor positioned with one end adjacent said end of the cylindrical support and a tubular terminal member for electrically connecting said lead to said resistance conductor compressed upon the adjacent ends of said cylindrical support andsaid lead.

8, An electrical heating unit comprising a substantially cylindrical, yielding support, a

resistance conductor wound upon said su port Substantially throughout its length, a lead for each end of said coiled resistance conductor, each lead having one'end'positioned in substantial alignment with the as sociated end of the cylindrical support, and a tubular terminal for each end of said resistance conductor whereby said end is mechanically and electrically connected with the adjacent end of its associated lead, saidterminal havin a stepped bore, one portion of said bore icing compressed about said end of the cylindrical support, while another portion of said bore is compressed about a portioniof said lead whereby the adjacent end of said lead isprovided with a head for preventing the withdrawal of said lead.

9. An electrical heater comprising an electrically insulating sheath having an o" n end, a supporting member mounted wit in said sheath, a resistance conductor mounted upon said supporting member, a lead projecting into said sheath through its open end and a terminal mounted within said sheath for electrically connectin said resistance con-' ductor with said lea said terminal being compressed about said supportin so as to be in electrical contact w1th a portion of said electrical, conductor.

10. A. heating unit com rising an electrically insulating sheath liaving an open end, a yielding supporting member mounted within said sheath, a resistance conductor wound upon said supporting member and a terminal mountedwithin said sheath, said terminal being compressed about said yielding supporting member so as to be in electrical contact with aportion of said electrical l conductor. a 11. A heatingunit comprising an electrically insulating sheath having an open end. a yielding supporting member mounted within said sheath, a resistance conductor co1led ,abou t said supporting member, a lead for said resistance conductor projecting from necting said resistance conductor an said lead comprising a tubular member mounted within said sheath -and compressed about a portion of the end turns of said coiled resistance conductor and the end portion of said lead.

12. An electrical heater comprising a pormember said open end and means for electricall concelain sheath having a passageway shaped in I I I the form of a hairpin, the ends of said passageway being open to the exterior of'the sheath, an asbestos supporting member mounted within said sheath so as to assume a substantially hairpin shape, a resistance conductor coiled about said supporting member, substantially throughout its length, a lead for each end of'said'coiled resistance conductor, said leads being projected into the open end portions of said passageway so as to be in substantial alignment withthe corlar terminal member mounted within each leg 7 of said passageway so as to receive the associated adjacent ends of said support and said leads, each terminal member being compressed about said adjacent ends so as to provide a firm mechanical and good electrical connection between the end turns of said resistance conductor and its leads.

13. The method of forming a heating unit which comprises winding a resistance conductor upon a yielding supporting member and then securing said resistance conductor to a lead by compressing a tubular terminal member about a portion of the resistance conductor and'a portion of said lead.

14:. The method of forming a heating unit which comprises coiling a resistance conductor upoma substantially cylindrical supporting member, then connecting a terminal member to the end of said coiled resistance unit and a lead by placing the adjacent ends of the supporting member and lead in a passageway formed in said terminal member whereby the terminal embraces the end turns of said coiled conductor and the end por tion of said lead and then swaging said terminal into firm mechanical and good electricalcontact with said resistance conductor and said lead.

15. The method of forming a heating unit which comprises winding a resistance conductor upon a yielding supporting member, then securing said resistance conductor to a lead by compressing a tubular terminal member about a portion of the resistance conductor and a portion of said lead and then surrounding said supporting member, resistance conductor and terminals with an electrically insulating covering.

16. The method of forming a heating unit which comprises coiling a resistance conductor upon a substantially cylindrical supporting member, then connecting a terminal member to the end of said coiled resistance unit and to a lead by placing the adjacent ends of the supporting member and lead in a passageway formed in said terminal member whereby the terminal embraces the end turns of said coiled conductor and the end portion of said lead, then swaging said terminal into ,Way of hairpin form is provided in said sheath for said heating unit.

In witness whereof, I have hereunto set my hand this 25th day of April, 1929.

CHARLES C. ABBOTT.

firm mechanical and good electrical contact with said resistance conductor and said lead, and then placing said support together with the coiled resistance conductor and its terminals into an electrically insulating porcelain sheath.

17. The method of forming an electrical heater which comprises providin a heating unit by winding a resistance con uctor upon a flexible supporting member, then shaping said heating unit to the form of a hairpin, then drawing the legs of said heating unit into an electrically insulating sheath having a recess in one end and a pair 'of spaced

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