US2931996A - Ballast resistor with sealed terminal means - Google Patents

Description

April 5, 1960 K. E. BRANDEBURG BALLAST REsrs'roR wml SEALED TERMINAL MEANS Filed July 28, 195e JNVENToA KENNETH E. BRANDEBURG ATTORNEYS United States Patent O BALLAST RESISTOR WITH SEALED TERMINAL MEANS Kenneth E. Brandeburg, Williston, Ohio Application July 28, 1958, Serial No. 751,508

7 Claims. (Cl. 3258-164) This invention relates generally to electrical apparatus, and, in its more specific aspects, to resistance units of the type that has particular utility as a ballast resistor in the primary or low voltage circuit of ignition systems for variable speed internal combustion engines.

The invention embraces a method and means for supporting, in non-conductive relation with respect to a metallic member, a current-consuming device, as well as holding in fixed and scaled relation to said member, two terminals of the device operating at different potentials.

This invention contemplates an integrated construction designed to provide a sealed terminal connector assembly at the point of passage through its enclosure, as well as holding the assembly, in non-conductive relation, with no physical connection at such point between the enclosure and the terminal.

This invention comprehends a terminal connector assembly for electrical apparatus wherein insulating means serves to effectively support, in non-conductive relation with the housing, the electrical device and its terminals and concurrently seals at their point of passage through the housing against the admission of moisture and other foreign matter, thereby producing a high temperature resistant, shock, and moisture-proof construction.

The invention is concerned with a unitary assembly for holding, in sealed non-conductive relation, two terminals of a current-conductive device operating at different'potentials, as well as supporting the device within an enclosure by single insulating means by properly spacing the device and terminals from the enclosure whereby physical connection therewith is provided solely by the ysaid insulating means.

According to the foregoing summary of the invention,

indicating its nature and substance, one of the main purposes is to solve the mechanical and electrical problems relating to a trouble-proof means for supporting and holding, in non-conductive relation with reference to a metallic enclosure, an electrical device and its terminals and maintaining the same in xed and sealed position, as well as preventing performance failures due to high temperature or vibration, as well as by operators establishing circuit connections therewith.

An object of this invention is to provide a resistance unit wherein its terminals are fixed to an insulator which is attached to the housing at points spaced from the terminals to thereby effectively prevent turning of the insulator when torque is applied to establish circuit connection with the terminals.

Another object of the invention is to provide a currentconducting unit wherein a one-piece insulator is the sole support for the unit and its terminals and is fixed to the housing at points spaced from the terminals to thereby constantly maintain in position the parts supported thereby, effectively preventing their relative motion with respect to insulator and housing.

Another object of the invention is to provide a resistance unit wherein the terminals are supported and-insu- ICC lated from the housing by a one-piece insulator having apertures mating non-circular sections of the terminals to thereby prevent the turning of the terminals with respect to the insulator when torque is applied to establish circuit connections therewith.

Another object of the invention is to provide a resistance unit wherein a one-piece insulator, provided with an interlocking connection with its terminals, effectively supports the unit within the housing and the terminals in non-conductive relation therewith, and, in addition, performs the function of sealing the assembly against the admission of moisture and other foreign matter.

Another object of the invention is to provide a terminal connector assembly for electrical apparatus wherein the enclosure is provided with raised ribs to allow circulation of air between the insulator and the enclosure whereby the insulator operates at a lower temperature, and thereby permits the use of low cost insulation.

Another object of the invention is to provide a terminal assembly in which the terminals of a currentconducting device are solely connected to the housing by the insulator and a part of the terminals is the sole means used for holding the terminals and insulator against axial movement.

Another object of the invention is to provide a unitary assembly wherein the terminals of a current-carrying device project through the housing, are supported and locked to an insulator against axial movement by the inclusion of a member arranged to provide spring pressure when compressed whereby the terminals and insulator are permanently maintained in non-relaxing, fixed relation.

Another object of the invention is to provide an integrated assembly for electrical apparatus adapted to operate at high temperatures wherein a one-piece insulator forms the sole connection of the apparatus with the housing which is dimensioned to bridge the distance .between the openings of the housing through which the terminals project and has a reduced intermediate section to thereby expose more area of the housing for improved heat transfer.

A further object of the invention is to provide an electric device wherein a one-piece nonconductive member functions in a fourfold manner: (l) as means to insulatingly hold two terminals of the current-conducting device operating at different potentials, (2) as means to maintain the terminals in fixed spaced relation with respect to the enclosure, (3) as means to prevent rotary movement of the terminals when torque is applied to establish circuit connection therewith by an operator, and (4) as means to provide an effective seal at the *point of their passage through the housing.

A further object of the invention is the provision of a terminal connector assembly wherein a one-piece insu- 'lator and the terminals have an interlocked connecticut including a member having a configuration which imparts springiness thereto to thereby hold the insulator and Vterminal in non-relaxing, fixed relation, compensating Y several views. i

Referring to the drawings: l

Fig. I is an isometric view of a resistance device illusf trating a form of the invention;

Fig. Il is a longitudinal, sectional view of the device shown in Fig. I; v

Fig. IH is a sectional view taken substantially in .lines IlI-III of Fig. Il looking in thev direction ofthe arrows;

Fig. IV is a sectional view taken substantially in lines V-1Vof Fig. Il looking inthe direction or" the arrows;

Fig. V is a bottom plan ViewV of the device shown in Fig. I with the lower member of the housing removed;

Fig. V1 is an enlargedsectional view of the terminal connector assembly; and

Fig. VII` is an enlarged sectional view of a modified form of .the .terminal connector assembly.

T he .invention may be incorporated in any type of electrical apparatus and vfor practicalapplication of its principles the same is illustrated as embodied in a resistance unitsuch as a ballast resistor used to reduce, under predetermined conditions, the primary or input current or" ignition systems for variable speed internal combustion engines. However, it is understood that the invention is not limited to the particular form illustrated and .that it is contemplated to use the same whenever. its

principles may be foundto .have utility.

Referring to the drawings, and particularly to Figs. 1I and V, it can be seen that the housing for a currentcarrying device such as the Yresistance unit ttl comprises two .metallic members .12 and 13 of complementary contour clamped together forming an elongated hollow case of rectangular shape, dimensioned to enclose the resistance unit. The .member 12, constituting the main support and enclosure is preferably fabricated of sheet metal comprising a uniplanar top wall 14 and the vertically depending parallel side Walls 15 and 16 forming an elongated channel. The end of each of the side walls 15 and 16, as shown in Fig. V, has a set of integrally formed spaced projections or clamping tabs 17, 18, and 19, respectively. These four tabs are inwardly bent to clamp and retain, in abutting engagement, the side walls with the planar section 21 of the closure or base member 13, as well as placing its upwardly directed legs 23 and 24 within the channel section of member 10 closing each end thereof.

in the form shown, the closure r13 has an extension 25 serving ask a fastening bracket vfor the unit, and is 'provided'with an opening 26 dimensioned and arranged to allow the passage `of the clamping tab 17 in order to aid lclamping the members together to P fOduce a. fluidtight housing.

The planar wall`14 of the main supporting member is pierced or formed with spaced openings 28 and 29, each dimensioned to allow the free passage of the electrical terminal connectors Si) and 31 of the resistance unit 10, providing an air space therebetween. The outer surface of the wall 14 ris provided with outwardly extending surfaces 32 and 33 adjacent to and surrounding each ofthe openings 28 and 29 which, as shown in Figs.

il and Vl, are in the form of integrally .struck up annular raised portions, each constituting a continuous projecting rib. -The wall 14 is also provided with outwardly directed conicalsections or projecting surfaces 34 and 36 terminating substantially Vin the same plane of the raised projecting surfaces 32 and 33, and Ythus provide supporting and Vfastening pads for a non-conducting member 37 disposed. in spaced relation between the openings 28 and 29.

rThe non-conductive member 37, which provides the main insulating and supporting means for the electric device-and its terminals operating at different potentials, is made as a single unit of a moisture-proof, high temperature, Vand llame-resistant insulating material. I have found, in practice, that effective performance is obtained by forming the member 37 as a one-pieceinsulator fabricated rom a laminated, thermosetting plasticnhavilg'an asbestos glass or synthetic fiber base. Moreover, that molded sheet insulation of the type vavailable under Athe trademarks Synthane or Spauldite, have the properties required to produce the non-conducting member 37, which not only serves as insulating and supporting means for the electrical components of the currentcarrying device, but which also functions in the fourfold manner set forth as an object of the invention.

The one-piece insulator 37 is dimensioned to bridge the distance between the openings 28 and 29, and extends over the projecting surfaces or raised annular portions 32 and 33, so that when the insulator 37 is fixed to the wail 14 of the housing by suitable means, such as rivets 38 and 39 projecting .through the fastening pads 34 and 36, its lower face is forced into tight engagement with the annular raised portions 32 and 33 to thereby seal the openings 28 and 29.

The insulator 37 is formed with an intermediate .portion'itt of reduced width in order to expose more area of the wall 14 for improved heat .transfer and to enhance the circulation of air in the space separating the insulator 37 from Ithe housing. The end sections of the insulator 37 are pierced .by non-circular apertures 41 and 42 disposed in axial alignmentv with the openings 28 and 29 which, as 'shown in Fig. III, are of a square contour. These square lapertures form a component of the nonrelaxing interlocked connection between the insulator 37 and each of the electrical terminals 30 and 31, which connection not only prevents relative rotary movement, but, in addition, axially maintains under constant spring pressure the insulator and terminals, preventing relative longitudinal movement therebetween.

The electrical terminals 30 and 31 are made of a suitable current-conducting material and, consistent with economical manufacture, have substantially the same shouldered configuration and, therefore, a detailed description of one terminal will only be necessary. As can be seen by examination of Fig. VI, where one terminal is shown in detail, the terminal includes a shoulder or horizontally disposed iange 43 located between 'a threaded top end 45 and an inner connector or terminal stud of suitable length and width to project within the housing through either of the openings 28 or 29, providing a substantial airspace therebetween. The shoulder 43 and threaded end 45 provide the external connector. or binding p'osts'used to establish circuit connections 4with the current-carrying device 1t? by means of the vterminal stud which support the device within the housing. The terminal stud comprises a shank 46 of noncircular configuration and a reduced cylindrical hollow tenon or tubular end section 47. The shank 46 is shaped to a contour complementary to mate the non-circular 'aperture of the insulator which, as shown in Fig. lll', is

formedV to a'square contour providing, in their interlocked connection, the means which prevents the turning of the terminal when torque is applied in establish- Ying circuit connections therewith.

Each one of the electrical terminals 30 and 31 is attached to the one-piece insulator 37 by means of a nonrelaxing, liquid-tight, sealed, interlocked connectiom'in which the non-relaxing feature is provided by interposing between the shoulder 43 of the terminalV and the upper face of the insulator 37 a ring-'like member 50 surrounding the shank 46. The member 50 has a congurationwhich imparts a springiness thereto and thereby provides a spring pressure when placed in compression, so that spring take-up is always present to compensate for possible looseness which may result from different eX- pansion of the terminal and insulator due to the operationof the unit under different temperature conditions, as `well as wide tolerances in their manufacture. I have found that the non-relaxing lfunction of member 50 can be effectively performed by the use of a lock washer and thus the non-relaxing function is securcdat very low As shown in Fig. VI, the terminal is fixed to the insulator 37, as well as to the resistance unit by swedging or flaring the end 51 of the hollow tenon 47 while placing under direct compression the lock washer S0 through the spacing bushing S3 interposed between the lower face 54 of the insulator and the upper face of the eyelet connector 56 of the resistance unit 10. Thus it can be seen that each one of the terminals and 31 is secured to the insulator 37 solely by an integral part of the respective terminals, and that such part also acts as means to anchor and electrically connect the :resistance unit 10 to the terminal proper. In this form of the invention, the spacing bushing 53, which surrounds the current-conducting tenon 47 of the terminal, is dimensioned with respect to the openings 28 or 29 of the housing to provide an air space therebetween. Examination of Fig. VI clearly shows that the insulator 37 is the sole support for both terminals and current-conducting unit, and serves to maintain the same in fixed nonconducting relation, providing the only physical connection of the electrical components with the housing, preventing the relative motion with respect to the insulator and housing. The resistance unit 10 is formed of two identical members or resistances 58 and 59 held in opposed relation, each comprising a pair of terminal eyelets, to which is attached the ends of a resistance wire 60 which takes the form of a coil having its convolutions wound on a ame and high temperature resistant insulating core 61.

In the modified form of the invention shown in Fig. VII, the housing for the current-carrying unit 10 is fashioned in the same manner as the one previously described and comprises two metallic members 70 and 71 in complementary contour clampedtogether. The metallic member 70, to which the one-piece insulator 72 is attached, has an opening 73 surrounded by an annular continuous rib 74 by which the opening is sealed by being directly engaged by the lower face of the insulator 72. In the modfied form of the invention, the terminal assembly incorporates the liquid-tight, sealed, non-relaxing, interlocked connection between the electrical terminal 75 and the insulator 72 which is identical in construction and configuration to insulator 37 hereinbefore described and which is also attached in the same manner to the housing wall 70.

The terminal connector 75 in this form of the invention comprises a shoulder 76 located between the threaded upper end or binding post 77 and the depending stud section which is dimensioned to project through the opening of the housing providing an air space therebetween. The terminal stud section co-mprises a shank 78 and a hollow tubular tenon 79. The shank 78 is shaped to a square contour adapted to be received in mating relationship with the square opening 80 piercing the insulator 72. A lock washer 81 is interposed between the shoulder 76 of the terminal 75 and the upper face ofthe insulator 72 to provide a permanent spring take-upto compensate for possible looseness resulting from different coeiiicientof expansion of the currentconducting material of the terminal 75 and the laminated synthetic thermosetting plastic from which the insulator 72 is fabricated.

In themodied form of the invention shown in Fig. VII, the terminal connector 75 is fixed to the one-piece insulator 72 by swaging or ring-staking portions 82 of the square contour 78 of the terminal over the spacing and retaining washer 83 which is in direct engagement with the lower face of the insulator 72. Thus the means for clamping the terminal 75 and the insulator 72 together with lock washer 81 compressing the same are provided solely by portions 82 of the terminal 75. The lower portion of the tubular tenon 79 of the terminal is formed with shoulder 84 which has a reduced end dimensioned to receive the terminal eyelet 85 and which, in turn, is ring-staked or swedged over the surface of the 6 eyelet to maintain the resistance unit l0 in fixed relation. The stud section of the terminal in this form of the invention has a suitable length to support the unit 10' in spaced relation with respect to the walls of the housing, and its overall width is dimensioned with respect to theV opening 73, so that an air space is provided therebetween. This air space, as well as the opening 73, is effectively sealed by the direct engagement of the insulator 72 with the raised portions or continuous rib 74 surrounding the opening 73. In this form of the invention the resistance unit 10 is identical in construction and arrangement to the resistance unit previously described.

The foregoing clearly shows that in the embodiments of the invention disclosed either of the one-piece, nonconducting members 37 or 72 not only serves as the sole support for the electrical components of the unit but, in addition, functions in a four-fold manner: (1) as means to insulatingly hold two terminals of the currentconducting device operating at different potentials, (2) as means to maintain the terminals in xed spaced relation with respect to the enclosure, (3) as means to prevent rotary movement ofthe terminals when torque is applied to establish circuit connection therewith by an operator, and (4) as means to provide an effective seal at the point of their passage through the housing.

It is to be understood that the above detailed description of the present invention is intended to disclose an embodiment thereof to those skilled in the art, but that the invention is not to be construed as limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of being practiced and carried out in various ways without departing from the spirit of the invention. The language used in the specification relating to the operation and function of the elements of the invention is employed for purposes of description and `not of limitation, and it is not intended to limit the scope of the following claims beyond the requirements of the prior art.

What is claimed:

1. A device of the class described comprising a housing having one of its walls provided with spaced openings, raised portions formed on the outer surface of the wall of said housing surrounding said openings, a resistance unit located within the housing having spaced terminals arranged and dimensioned to project through the openings of said housing providing an air space therebetween, said terminals having a non-circular section, a one-piece insulator dimensioned to bridge the distance between the said openings and extend over said raised portions, forming an air space between said housing wall and said insulator, non-circular apertures piercing said insulator arranged to receive the non-circular section of said terminals in their passage through the openings of said housing, means forming integral parts of said terminals permanently holding said terminals and insulator in non-relaxing fixed relation including a resilient member held under compression, and means spaced from the said openings for holding said one-piece insulator externally of said housing in tight engagement with said raised portions to thereby seal the air space between said terminals and the openings of said housing and concurrently maintain the terminals and resistance unit in non-conductive relation with the housing.

2. A device of the class described comprising a housing having a wall of sheet metal pierced by spaced openings, raised portions formed on the external surface of the sheet metal wall of said housing surrounding the said openings, the terminals of a current-carrying unit arranged to project through the openings of said housing, said terminals having a shank provided with a non-circular section, a uniplanar insulator formed with non-circular apertures arranged to receive the non-circular section of the shank of said terminals and being dimensioned to bridge the distance .between said openings and extend angliae@ over said raised portions forming .an airspace between to said insulator, and means exterior of ysaid openingsy for holding said insulator externally of saidhousing in direct engagement with the said raised portions to there-k by seal theopenings of said housing and maintain Vthe terminals in non-conductive relation with the housing.

3. A device of the class described comprising a Vhousing having a metallic wall pierced by spaced openings, surfaces extending outwardly from the external surface of the metallic wall of said housing adjacent to said openings, the terminal connectors of a current-carrying unit provided with a horizontally disposed flange and a depending section arrangedand dimensioned to project through the openings of the metallic wall of said housing in spaced relation therewithV forming an air space therebetween, va non-circular portion provided on the depending section of said terminals, an insulating member of substantially uniform thickness formedwith non-circular apertures arranged to receivethe noncircular portion of said terminals andv being dimensioned to bridge the disg tance betwee-n said openings and to extend over said outwardly extending surfaces forming an air space between saidmetallic wall and saidv insulating member, means including the horizontally disposed flange and a portion of the depending section of said terminal holding in non-` relaxing iixed relation each one of said terminals to said insulator, and means including outwardly extending fastenand,` a shank, the shank of said terminals projecting through said openings and through said insulator, meansrv includingthe kshoulder and an integral part of said termi; nals holding said terminals and insulator against relative axialandV rotary movements, and means including outwardly extending fastening pads securing said insulator to said member in engagement with said outwardly exf tending surfaces sealing thereby the openings of said` member. l

6. In combination, a current-conducting member having a .uniplanar surface pierced by an opening, integrally formed outwardly projecting surfaces adjacent to said opening, an insulator having a uniplanar surface of sub1 stantially uniform thickness dimensioned to cover said opening and engage said projecting surfacesV forming an air space between said uniplanar surfaces a terminalconfing pads exteriorrof said openings for holdng said insulating member externally of said housing in dIrect engagement with said outwardly extending surfaces to thereby seal the space between said terminals and the openings of said housing and maintain the terminal connectors in non-conductive relation with the housing.

4. A device of the class described comprising a metallic housing pierced by spaced openings, `the terminals of a current-carrying unit having a shoulder and a depending shank arranged to project through the openings of said `housing forming an air space therebetween, a non-circular section providedon the shank of said terminals, an insulating member formed with non-circular` apertures arrangedvto receive the non-circular section` of said terminals, said'insulator insulating member having a uniplanar surface being dimensioned to bridge the distance between the opening of said housing and extended over the same, means provided by the shoulder and a distorted portion of the shank of Isaid terminals for holding in axial xed relation the non-circular section of each one of said terminals in the non-circular apertures of said insulating member, and means spaced from the openings of said housing holding said insulating member externally of said housing covering the openings of the housing to thereby seal the said openings and maintain the terminals innonconductive relation with the housing.

5. In combination, a metallic member pierced by spaced openings, outwardly extending surfaces surrounding said l openings, an insulator of flame-resistant sheet material dimensioned-to bridge the distancebetween said openings and tofengage said outwardlyextending surfaces forming an. air space between said member and said insulator, terminalsv of a current-carryingdevice having a shoulder nector having a shoulder and a depending shank passing through said insulator and dimensioned to project 'through` said opening providing a space therebetween, an inter? locked connection between said terminal and insulator, a member having a configuration which imparts springf4 iness thereto placed under compression between the shoulder andk a portion of the shank of Vsaid terminals forming a part of said connection, and means comprising an outwardly projecting fastening pad terminating substantially in the plane of said` outwardly projecting surfaces securing said insulator in engagement with said projecting surfaces to thereby seal the space between said terminal and opening.

7. A device of the class described comprising a housing having one of its walls provided with an opening, raised portions formed on the outer surface of the wa 11 of said housing surrounding said opening, a resistance unit located within the housing, a shouldered terminal of said resistance unit having a depending section arranged and dimensioned to project through the opening of said housing providing an air space therebetween, a non-circular reduced portion formed on the section depending from the shoulder of said terminal, an insulator dimensioned to cover the said opening and extend over said raised portions, a non-circular aperture piercing said insulator arranged to receive the non-circular reduced section of said terminal in its passage through the said opening, a member surrounding said non-circular section located between the said shoulder of said terminal and said insulator, lsaid member having a configuration which provides spring pressure when placed in compression, means including a part of the depending section of said terminal for holding said insulator and member under compression against axial movementwhereby said termi'- nal and insulator are constantly maintained under spring pressure, and means for holding said insulator in tight engagement with said raised portions to thereby seal the air space between said insulator and said opening and con'- currently maintain the said terminal in non-conductive relation with the housing,

References Cited in the tile of this patent UNITED STATES PATENTS 1,321,873y Ziegler Nov. 18, 1919 2,747,071 Schlumbohm May 22, 1956 2,808,152 Kaufman Oct. 1, 1957 UNITED STATES PATENT OFFICE l CERTIFICATE OF CORRECTION Patent Not, 2,93li996 April 5, 1960 Kenneth Eo Brandeburg It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 7, line 45, after "said" strike out "'insulater"a Signed and sealed this lst day of November 1960o (SEAL) Attest:

KARL H.. AXLINE ROBERT C. WATSON Attesting Officer Commissioner of Patents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTIUN Patent Nm` 2,93li996 April 5, 1960 Kenneth E Brandeburg It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should -readas corrected below.

Column 7, line l5i after "said" strike out "'insuleltort2 Signed and sealed this lst day of November l960 SEAL) Attest:

KARL Hb AXLINE ROBERT C. WATSON Attesting cer Commissioner of Patents

Images