US3151309A

US3151309A - Electrical trimming connector

Info

Publication number: US3151309A
Application number: US73652A
Authority: US
Inventors: Arthur H Kuriloff
Original assignee: NON LINEAR SYSTEMS Inc
Current assignee: NON LINEAR SYSTEMS Inc
Priority date: 1960-12-05
Filing date: 1960-12-05
Publication date: 1964-09-29
Anticipated expiration: 1981-09-29

Description

Sept. 29, 1964 u o 3,151,309

ELECTRICAL TRIMMING CONNECTOR Filed Dec. 5, 1960 INVENTOR.

ARTHUR 6 Kan/z. arr

Asewr 3,151,309 1C6 P t nted Sept. 29, 1964 3,151,309 ELECTRHCAL TRIMMING CQNNECTOR Arthur H. Kurilofi, San Diego, Calif., assignor to Non- Linear Systems Inc, Del Mar, Calif, a corporation of California Filed Dec. 5, 19663, Ser. No. 73,652 9 Claims. (Cl. 338-269) This invention relates to an electrical trimming connector and it is particularly concerned with the trimming of the terminal end of a resistance conductor and with the securement thereof for the conduction of current, it being a general object of this invention to provide a practical connector by which the last point of contact with the conductor can be adjustably carried as circumstances require.

In electronics the exact length of a conductor is a critical factor in many instances. For example, in a resistance winding it is necessary to carefully trim the terminal end or ends of the conductor element and to carefully secure said ends to electrical leads. Any deviation from the required length of said conductor element will result in discrepancies in the resistance afforded thereby, and one turn, more or less, cannot be permitted. Further, the problems involved are augmented by the fact that resistance wires are very often extremely fine and delicate, and the unit that is finally produced is therefore very small. Thus, a connection for use with fine resistance wires and in the manufacture of small sized units must be small, light-weight, and capable of manipulation when engaged with said wire for trimming and securement.

An object of this invention is to provide a solder connector for use in trimming and securing a resistance wire to a lead wire. Generally, the current carrying capacity of the lead wire is far greater than that of the resistance wire and the present invention contemplates supporting or carrying of the connector or said lead wire, said connector being characterized by its bushing formation.

Another object of this invention is to provide a connector of the character referred to that is selectively adjustable in order to adjust the point of contact between the resistance wire and the connect or bushing, and to thereby selectively vary the length of said resistance wire. More particularly, the bushing is spool-shaped and such that it can be turned and to the end that the resistance wire extends tangentially therefrom at any selected peripheral point of contact.

it is still another object of this invention to provide a connector of the character referred to that provides a heat-sink for the absorption of heat when the lead wire of the finished unit is connected in a circuitry. Obviously, when heat is applied to the lead wire, even when remote, there is the danger that said heat will be conducted via said lead wire to enter the resistance unit and thereby to alter the same.

The various objects and features of my invention will be fully understood from the following detailed description of the typical preferred form and application of my invention, throughout which description reference is made to the accompanying drawings, in which:

FIG. 1 is a perspective view of a typical embodiment of the present invention and an electrical resistor. FIG. 2 is an enlarged perspective view of the connector or termination bushing as provided by the invention. MG. 3 is an enlarged longitudinal sectional view of the resistor of FIG. 1 and showing the installation of a pair of termination bushings of FIG. 2. FIG. 4 is an enlarged sectional view of the entire resistor of FIGS. 1 and 3, without the encompassing body thereof and taken as indicated by line d-4 on FIG. 3. FIG. 5 is an end view of the structure taken as indicated by line 55 on PEG. 4,

and FIG. 6 is an enlarged detailed sectional view taken as indicated by line 66 on FIG. 5.

The connector bushing herein disclosed is particularly useful in the manufacture of electronic components or units, such as, for example, in the manufacture of resistors wherein a conductor of precise length is involved. Therefore, I will describe my invention as it is particularly related to the manufacture of resistors, or the like, and in which case the connector will be referred to specificially as a termination bushing. It is to be understood, however, that the connector is useful in any like situation where one electrical conductor is secured to another for conduction of current.

in FIG. 1 of the drawings I have shown an electric component in the form of a resistor A and such as to include the termination bushing of the present invention, said component being shown substantially full scale. In FIG. 2 a termination bushing B is shown as it appears by itself and removed from the structure of the resistor A. As is illustrated, the resistor A is an elongate cylindrical component having lead wires C projecting therefrom, and in the case illustrated there is a pair of lead wires C, each projecting oppositely on a common central axis. In accordance with common practice, the resistance wire D is an elongate filament that is carried by winding it upon or around a bobbin E, said bobbin forming the frame element of the component. The entire component is shown as being encapsulated or molded within an encompassing body F of epoxy material that protects it.

In FIG. 4 of the drawings I have shown the entire component less the encompassing body F, this being the stage of assembly when the connector or connectors in the form of the termination bushing B are secured to the wires to be joined electrically. As clearly illustrated, the two lead wires C project from opposite ends of the bobbin E, centrally thereof, and the resistance wire D is wound onto the bobbin with its opposite terminal ends secured to a termination bushing B, respectively. In practice, the bobbin E is an elongate part formed on a central axis and it has a core N with

end flanges

11 and 12 projecting radially from the said core. Further, it is preferred that there be a central flange 13 in order to establish two separate winding areas, the flanges being of uniform diameter. The bobbin E is made of dielectric insulating material, the two opposite lead wires C being mounted by their inner end portions that are enlarged by upsetting and which are embedded in the opposite end portions of the core Ill. In practice, the enlarged inner ends of the leads C are pressed in a bore that extends through the bobbin E. With the bobbin E thus formed, the resistance wire D is wound in one direction of rotation in the area at one side of the flange l3 and in the other direction at the other side of said flange. As shown in FIGS. 4 and 5 the flanges ll, 12 and 13 are slotted in order to pass the resistance wire D from and between the said winding areas.

The lead wires C, above referred to, are round in crosssection and are made of soft metal adapted particularly to the making up of soldered connections with other condoctors, for example of soft oxygen free copper. The

opposite ends

15 and 16 of the bobbin E are flat and parallel and normal to the axis of the lead wires C, respectively. In accordance with the invention, the termination bushing B is a spool-shaped element that is engaged over the lead wire C, in this instance there being a pair of bushings B, one adjacent the end 15 and one adjacent the end 16. As best illustrated in FIGS. 5 and 6, the resistance wire D, or filament, is connected to the lead wire C by securernent to the bushing B.

In accordance with the invention, the termination bushing B is a metallic part, preferably made of a soft metal of high conductivity, for example of a free-machiningbrass. As shown, the spool-shaped bushing B is of circular configuration and is therefore adapted tobe turned, having a drum-shaped body with

end flanges

21 and 22. The body 20 is cylindrical with concentric bore 23 extending axially therethrough to freely pass the diameter of the lead wire C. The flanges are at opposite ends of the bushing B and are flat and parallel and normal to the axis of the body 20. The said

flanges

21 and 22 are as thin, in axial dimension, as is practical to machine them, they are spaced axially from each other a distance to accommodate several turns of resistance wire D, and they are of a diameter approximately twice that of the body 20. A typical bushing B has a total axial extent of .040 of an inch and an outside diameter of .070 of an inch.

In carrying out the invention the termination end portion of the resistance wire D is stripped of insulation, common to such wire, and said termination end portion 30 is drawn through the slot in the end flange of the bobbin E (see FIG. 5). The attachment or securement of the opposite ends of the who D can be alike, or identical, and therefore a description of one suffices for both. In FIGS. 5 and 6 I have shown the manner in which the wire D wraps onto the body 20 and extends tangentially therefrom. The bushing B is rotatable on the lead wire C facilitating the wrapping of several turns of the Wire D onto the cylindrical body 20. In carrying out the invention the bared end portion of the resistance wire D is held engaged laterally against the inner face of the

flange

21 or 22, this being readily accomplished manually or by lateral pressure exerted by wrapping several turns of wire D onto the body 20, as shown. In any case, the last point of contact will be established at X at the periphery of the flange which is engaged laterally by the wire D.

With the parts and relationship thereof, as above described, the last point of contact X is readily adjusted relative to the length of the resistance wire D by wrapping or unwrapping the wire D on the body 2 3, with said wire engaged laterally against the

flange

21 or 22, as the case may be. For example, in fabricating precision wire-wound resistors, the last point of contact is determined by reading the total resistance from lead to lead with a sensitive wheatstone bridge or galvanometer type instrument. This reading is performed continuously in the trimming operation and the percise point for terminating is established readily by incremental adjustment. Having made the precise adjustment desired, as measured by suitable instruments, the final and permanent securement is made by the application of a body of solder. It is preferred therefore, that the bushing B be tin-plated and only that amount or volume of solders is applied such as to bridge or fill between the flanges 2i and 2-2, and also between the body 20 and lead wire C. Thus, the last point of contact X is not altered by the soldering process and as a result the electrical connection is precisely accomplished with simultaneous attachment of the bushing B in working position on the lead wire C adjacent the end of the bobbin B.

From the foregoing it will be understood how the bared end portion of the resistance wire is adjustably secured to an externally projecting lead wire. In practice, a relative high melting point solder can be employed in securement of the resistance wire D to the lead wire C through the termination bushing B, to the end that subsequent soldering applied to the lead wire C when the resistor is employed in an electronic circuit will not advertently loosen said connection. However, a feature of the bushing B is that it affords protection against remelting of the first mentioned solder connection by establishing a heat-sink that absorbs substantial heat, thereby materially lessening the danger of disturbing said last point of contact X between the wire D and bushing B.

Having described only a typical preferred form and application of my invention, I do not wish to be limited 4i or restricted to the specific details herein set forth, but I wish to reserve to myself any variations or modifications that may appear to those skilled in the art and fall within the scope of the following claims.

Having described my invention, I claim:

1. An electrical connector for adjustably trimming the end of a first conductor and for securement thereof to a second conductor, and including, a spool-shaped bushing of electrically conductive material and haying a bore therethrough to pass the second conductor and having a cylindrical body upon which the first conductor is wrapped and having a flange to laterally engage the said first conductor to extend tangentially from a selected peripheral point of contact with said flanges.

2. An electrical conector for adjustably trimming the end of a first conductor and for securement thereof to a second conductor, and including, a spool-shaped bushing of electrically conductive material and having a bore therethrough to pass the second conductor and having a cylindrical body upon which the first conductor is wrapped and having a pair of spaced end flanges to laterally engage the said first conductor to extend tangentially from a selected peripheral point of contact.

3. An electrical connector for adjustably trimming the end of a first conductor and for securement thereof to a second conductor, and including, a spool-shaped bushing of electrically conductive material and having a bore therethrough to rotatably pass the second conductor and having a cylindrical body upon which the first conductor is wrapped and having a flange to later-ally engage the said first conductor to extend tangentially from a selected peripheral point of contact with said flanges.

4. An electrical connector for adjustably trimming the end of a first conductor and for securement thereof to a second conductor, and including, a spool-shaped bushing of electrically conductive material and having a bore therethrough to rotatably pass the second conductor and having a cylindrical body upon which the first conductor is wrapped and having a pair of spaced end flanges to laterally engage the said first conductor to extend tangentially from a selected peripheral point of contact.

5. In combination with an electrical resistor comprising a bobbin with a projecting lead conductor and with a resistance conductor wound on said bobbin for trimmed connection to said lead conductor, a spool-shaped bushing of electrically conductive material rotatably engaged over said lead conductor and upon which the said resistance conductor is Wrapped to extend tangentially from a selected peripheral point of contact.

6. in combination with an electrical resistor comprising a bobbin with a projecting lead conductor and with a resistance conductor wound on said bobbin for trimmed connection to said lead conductor, a spool-shaped bushing of electrically conductive material rotatably engaged over said lead conductor and having a cylindrical body upon which the said resistance conductor is wrapped to extend tangentially from a selected peripheral point of contact.

7. In combination with an electrical resistor comprising a bobbin with a projecting lead conductor and with a resistance conductor wound on said bobbin for trimmed connection to said lead conductor, a spool-shaped bushing of electrically conductive material rotatably engaged over said lead conductor and having a cylindrical body upon which the said resistance conductor is wrapped and having a flange to laterally engage the said resistance conductor to extend tangentially from a selected peripheral point of contact with said flange.

8. In combination with an electrical resistor comprising a bobbin with a projecting lead conductor and with a resistance conductor wound on said bobbin for trimmed connection to said lead conductor, a spool-shaped bushing of electrically conductive material rotatably engaged over said lead conductor and having a cylindrical body upon which the said resistance conductor is wrapped and having a pair of spaced end flanges to laterally engage the said resistance conductor to extend tangentially from a selected peripheral point of contact with one of said flanges.

9. In combination with an electrical resistor compris- 5 ing a bobbin of dielectric material with at least one projecting lead conductor and with a. resistance conductor wound on said bobbin for trimmed connection to said projecting lead conductor, a spool-shaped termination bushing of electrically conductive material with a 1 bore therethrough so as to engage rotatably over said lead conductor and having a cylindrical body upon which References Cited in the file of this patent UNITED STATES PATENTS 2,487,057 Kohring Nov. 8, 1949 2,547,405 Mitchell et a1. Apr. 3, 1951 2,985,951 Solow May 30, 1961