US3208036A

US3208036A - Re-inforced lead wires

Info

Publication number: US3208036A
Application number: US143820A
Authority: US
Inventors: Harrison William Joseph
Original assignee: AMF Inc
Current assignee: AMF Inc
Priority date: 1961-10-09
Filing date: 1961-10-09
Publication date: 1965-09-21
Anticipated expiration: 1982-09-21

Description

P 21, 1965 w. J. HARRISON 3,208,036

RE-INFORCED LEAD WIRES Filed Oct. 9, 1961 INVENTOR 24 William J. Harrison mg zm ATTORNEY-5 United States Patent 3,208,036 REINFORCED LEAD WIRES William Joseph Harrison, Mount Carmel, 11]., assignor to American Machine & Foundry Co., a corporation of New Jersey Filed Oct. 9, 1961, Ser. No. 143,820 2 Claims. (Cl. 339-275) This invention relates to a re-inforced lead-out wire structure for fine wire electric coils and the like such as in relay coils, transformers, wirebound resistances, etc. and to methods and apparatus for making the same.

One of the weakest points in the structure of an electrical coil is adjacent the terminals where the delicate lead-out wire is brought from the ends of the coil to some type of terminal connection. With the fine sizes of wires utilized, this portion of the wire is particularly susceptible to breakage during manufacture of the coil and subsequent installation thereof. Furthermore, during operation of a relay or like device in which the coil is installed, the unit is generally subjected to a substantial amount of vibration, providing another possible cause of breakage.

The problem of re-inforcing the delicate lead-out wire has been recognized in the past and has been partially solved by one of several structures. For example, the lead-out wire can be wound about a heavy supporting wire for strength, or may be interlaced with a plurality of smaller wires to similarly provide a strengthened portion. In these structures, either the strengthening wires are uninsulated or else the end of the strengthening wire spaced from the terminal is bare and exposed. Additional insulation is therefore required, surrounding the lead-out structure to insulate the structure from the remaining portion of the coil. The requirement for this insulation adds expense, and causes a lump in the finished coil which substantially reduces the available winding space. Another disadvantage of prior structures of this type is that they often result in a stress concentration spaced from the terminal point, therefore creating a new weak spot in the lead-out wire.

This invention provides a lead-out structure, and a method of making the same, which avoids the problems encountered with lead-out wire arrangements re-inforced in accordance with prior art proposals. The reinforced portion of the lead-out wire is so arranged that no additional insulation is required and expense and space requirements are therefore reduced. Furthermore, the lead-out structure of this invention permits ease of manufacturing, further reducing the cost of this structure.

The unique results in accordance with this invention are achieved by employing an insulated reinforcing wire having an open loop configuration. This loop is interlaced with the lead-out wire in the form of a stable twisted structure. More specifically, the loop is twisted to form two identical helices side by side about the same center defining a continuous helical valley between adjacent convolutions. The lead-out wire nests in the helical valley so defined. The resulting structure has three loose ends, i.e., two ends from the loop and one from the leadout wire, with the bend of the loop spaced a substantial distance therefrom. The lead-out wire emerges from the structure by passing through the loop formed by the bend. This lead-out structure can then be completed by fastening all of the ends to a terminal connector by means of a single solder joint. A unique feature of this structure is that the reinforcing wire is completely insulated at all points spaced from the terminal connection and therefore no additional insulation is required for the strengthening structure.

The unique method for forming this re-inforced leadout structure includes the operational steps of first form- 32%,036 Patented Sept. 21, 1965 ing an open elongated loop of insulated Wire, the loose ends thereof being spaced from the center line of the loop. Next, the fine lead-out wire is positioned between adjacent sides of the loop somewhat off center. Then, while maintaining the spatial relationship between the three ends, i.e., the loose ends of the loop and one end of the lead-out wire, they are rotated relative to the bent portion of the loop. The resulting structure of intertwined wires forms a stable twisted configuration acting as a reinforced leadout wire.

The apparatus for carrying out the method in accordance with this invention is relatively inexpensive and simple. The basic components are a coil spring rotatable about its center and a stationary post member. The three ends are secured between adjacent coils of the spring with a friction grip, this grip supplying proper tension to the wires. The post member is adapted to retain the bend of the loop stationary when the spring rotates.

In order that the manner in which these and other objects are attained in accordance with the invention can be understood in detail, reference is had to the accompanying drawings, which form a part of this specification, and wherein:

FIG. 1 is a perspective view showing the forming of an elongated loop of insulated reinforcing wire;

FIG. 1a is a sideview of a portion of the unit of FIG. 1;

FIG. 2 is a similar perspective view illustrating the positioning of a lead-out wire with respect to the loop;

FIG. 3 is a perspective view showing the loop and lead-out wire after being intertwined;

FIG. 4 is a perspective view illustrating the completed lead-out structure;

FIG. 4a is an enlarged fragmentary perspective view of a portion of the leadout structure shown in FIG. 4'; and

FIG. 5 is a perspective view of the lead-out structure installed on a coil form preparatory to winding of the coil.

Suitable apparatus for constructing a re-inforoed leadout wire is shown in simplified form in FIGS. 1-3 and includes an electric motor 1 positioned on a mounting block 13a secured to a base member 13. The motor has a rotatable driven shaft 2. Securely fastened to shaft 2 is a rigid U-shaped member or yoke 3 adapted to maintain a coil spring 4 between the legs or extended portions 3a thereof. Member 3 is so mounted on shaft 2 by that of offset portion 2a that, when spring 4 extends between the legs of member 3 in straight line fashion, as illustrated in FIGS. 1 and la, the spring is centered on the axis of rotation of the shaft. Spring 4 is so dimensioned that, with its ends attached to the legs of member 3, the spring is substantially relaxed, so that its adjacent convolutions are closely adjacent to each other.

A stud member or post 5 is mounted on base member 13 at a point spaced axially a substantial distance from the end of shaft 2. Post 5 extends in a line which is at right angles to, and intersects, the axis of rotation of shaft 12. At its tip, the post has a portion 6 of reduced diameter to receive the bend of elongated wire loop 7.

Loop 7 is formed of a suitable insulated wire. Normally, this wire is of a somewhat larger diameter than the lead-out wire to be re-inforced and is preferably a multi-strand wire. The nature of the insulation on the wire of the loop depends mainly upon the contemplated use of the coil being constructed, the insulation being designed to withstand the potential and temperatures contemplated for the coil. One of the more advantageous types of wire which may be employed for the loop 7 is a multi-strand wire containing, for example, two or three strands approximately the same size as the lead-out wire, this multi-strand wire being coated by a continuous film of polyethylene, nylon, polytetrafluoroethylene or like resinous material. This type of multi-strand wire has the advantage of providing a twisted irregular outer surface providing space within which the lead-out wire may nest.

The open elongated loop 7 is substantially V-shaped and has two

adjacent sides

8 and 9. The rounded bend 10 of the loop is engaged about reduced tip portion 6 of stud 5, the free ends of the loop, i.e., ends 11 and 12, being each secured in spring 4 by pressing the wire between adjacent coils. Ends 11 and 12 are spaced at equal distances from the center of the spring, and thus from the axis of rotation of shaft 2.

Lead-out wire 14 is then placed over the center of the tip 6 of stud and secured in spring 4, as shown in FIG. 2. Lead-out wire 14 is located between adjacent sides 8 and'9 but is secured in spring 4 at a point somewhat off center, and, as shown in FIG. 2, is fastened closer to end 11 than to end 12. Lead-out wire 14 is usually a very small diameter wire and therefore cannot be forced into spring 4 as this would often cause breakage of the wire. Therefore, a suitable means (not shown) such as a lever or plunger arrangement is employed to bow out spring 4 into the position shown in FIG. 2. In this position, adjacent coils of spring 4 are separated somewhat on the upper surface of the spring (as viewed), this separation allowing the lead-out wire to be inserted between adjacent convolutions of the spring without danger of breakage. Spring 4 is then permitted to return to its normal position, so that the adjacent convolutions clamp the lead-out wire in a position aligned with ends 11 and 12.

Once the loop and the lead-out wire are positioned as shown in FIG. 2, motor 1 is turned on and permitted to rotate for a predetermined number of revolutions. Rotation of the motor rotates yoke 3 and spring 4 to twist the wires, this twisting resulting in a shortening of the distance between the

ends

11, 12 and 15 and the bend 10. As this shortening takes place, the ends slide through the spring, the friction grip of the spring maintaining the required tension on the wires. As shown in FIG. 3, the length of

ends

11, 12 and 15 is less after the twisting operation is completed.

FIG. 4a shows the resulting twisted configuration. The adjacent sides of the loop, being of the larger diameter stranded wire, form two

identical helices

16 and 17 side by side about the same center. The

helices

16 and 17 define two separate identical

helical valleys

18 and 19 between adjacent convolutions of

helices

16 and 17. The fine lead-out wire 14 nests in the helical valley 18. This twisted configuration of intertwined or interlaced wires is relatively stable and does not tend to unravel and therefore lead-out wire 14 cannot easily come free.

Once the twisting operation is completed, the bend is removed from stud 5 and the entire assembly merely pulled out of spring 4. The loose ends 11, 12 and are shortened and then securely fastened to a terminal lug 21 by means of a single solder joint 22, as shown in FIG. 4. v

The re-inforced lead portion 27 can then be positioned on a coil winding bobbin, as shown in FIG. 5. The bobbin on which the coil is to be formed includes ends 24 and 25 and a spindle 26 connecting the ends. The reinforced lead 27 is positioned adjacent end 25, reaching to the spindle 26. The re-inforced portion is maintained in position by a split washer 28 having a slot 29 which permits the washer to be slid into position around the bobbin spindle 26. Once the re-inforced lead-out wire is positioned and secured, the bobbin is rotated to wind a coil with the fine wire 30 which connects to terminal lug 31 via re-inforced lead portion 27. When the coil is completed, the other end of the coil is similarly re-inforced to provide the second strengthened lead-out wire.

While the most advantageous embodiment of the present invention has been shown, the scope of the invention is by no means limited thereto. The scope of the present invention is more specifically defined in the appended claims.

What is claimed is:

1. A re-inforced electrical coil lead comprising a coil lead wire of small diameter and terminating in a free end; a re-inforcing strand of substantially larger diameter than said coil lead wire and having two free ends, the central portion of said re-inforcing strand extending in the form of a small closed free loop and the portions of said re-inforcing strand between said loop and the free ends of said strand being twisted together in the form of two side-by-side helices having a common central axis, said helices defining a continuous helical valley, said coil lead wire extending from its free end along said continuous helical valley and being nested therein, said coil lead wire emerging through said closed free loop and said loop being adjacent to the emerging portion of said coil lead wire, said free ends of said re-inforcing strand and said free end of said coil lead wire all being mutually adjacent; and an electrical terminal member to which all of said free ends are physically attached and electrically connected.

2. A re-inforced electrical coil lead according to claim 1, wherein said re-inf-orcing strand is a multiple strand wire carrying a continuous film of electrical insulating material.

References Cited by the Examiner UNITED STATES PATENTS 605,930 6/08 Stauffer 140-90 1,442,648 1/23 Carter 338-322 X 1,672,866 6/28 Adams.

1,764,592 6/30 Adams 140-149 1,900,585 3/33 Reed 339275 2,694,419 11/54 Larsen 140149 2,760,178 8/56 Schaefer 339-275 2,829,226 4/58 Ripley. 2,835,283 5/58 Thone et a1. 140-149 2,943,135 6/ Bertling 174-79 X 7 FOREIGN PATENTS 584,027 1/47 Great Britain.

JOSEPH D. SEERS, Primary Examiner.

ALBERT H. KAMPE, Examiner.

Claims

1. A RE-INFORCED ELECTRICAL COIL LEAD COMPRISING A COIL LEAD WIRE OF SMALL DIAMETER AND TERMINATING IN A FREE END; A RE-INFORCING STRAND OF SUBSTANTIALLY LARGER DIAMETER THAN SAID COIL LEAD WIRE AND HAVING TWO FREE ENDS, THE CENTRAL PORTION OF SAID RE-INFORCING STRAND EXTENDING IN TGE FORM OF A SMALL CLOSED FREE LOOP AND THE PORTIONS OF SAID RE-INFORCING STRAND BETWEEN SAID LOOP AND THE FREE ENDS OF SAID STRAND BEING TWISTED TOGETHER IN THE FORM OF TWO SIDE-BY-SIDE HELICES HAVING A COMMON CENTRAL AXIS, SAID HELICES DEFINING A CONTINUOUS HELICAL VALLEY, SAID COIL LEAD WIRE EXTENDING FROM ITS FREE END ALONG SAID CONTINUOUS HELICAL VALLEY AND BEING NESTED THEREIN, SAID COIL LEAD WIRE EMERGING THROUGH SAID CLOSED FREE LOOP AND SAID LOOP BEING ADJACENT TO THE EMERGING PORTION OF SAID COIL LEAD WIRE, SAID FREE ENDS OF SAID RE-INFORCING STRAND AND SAID FREE END OF SAID COIL LEAD WIRE ALL BEING MUTUALLY ADJACENT; AND AN ELECTRICAL TERMINAL MEMBER TO WHICH ALL OF SAID FREE ENDS ARE PHYSICALLY ATTACHED AND ELECTRICALLY CONNECTED.