US 3032602 A
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Description (OCR text may contain errors)
May 1, 196 s. J. FARNELL ELECTRICAL CONNECTOR Original Filed Sept. 19, 1957 INVENTOR. SAMUEL J. FAB/Vfll H15 ATTORNEY 2 Sheets-Sheet l May 1, 1962 s. J. FARNELL ELECTRICAL CONNECTOR Original Filed Sept. 19, 1957 2 Sheet-Sheet 2 INVENTOR. .S/HVUH. J. FA HNELI.
BY Q .2
H15 ATTOH/Vii United States Patent ELECTRICAL CONNECTOR Samuel J. Farnell, Warren, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Continuation of application Ser. No. 684,991, Sept. 19, 1957. This application Dec. 16, 1959, Ser. No. 859,906 3 Claims. (Cl. 174-90) This invention relates to a terminal or electric connector, and particularly to a terminal having attachment means for applying the terminal to the end of a stranded conductor.
This application is a continuation of application S.N. 684,991 filed September 19, 1957, now abandoned.
An object of the invention is to provide an attachment means for mechanically securing a terminal to a stranded conductor by crimping or clamping a ferrule portion of a terminal onto the stranded wire of a conductor in a manner to provide a high resistance to pull out of the conductor from the terminal and also provide low electrical resistance in the mechanical connection of the terminal to the wire and also enclose the strands of the wire at the mechanical attachment of the terminal to the wire to reduce oxidation of the wire and terminal surfaces within the area of attachment which thereby avoids increase of resistance by aging.
Further objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.
In the drawings:
FIGURE 1 is an elevational view of a terminal having the mechanical attachment feature of this invention.
FIGURE 2 is a side elevational view of the terminal of FIGURE 1.
FIGURE 3 is a perspective elevational view illustrating a terminal in position for attachment to the end of a conductor.
.FIGURE 4 is a perspective elevational view showing the completed mechanical attachment of the terminal to a conductor.
FIGURE 5 is across-sectional view of the mechanical attachment taken along line 55 of FIGURE 1.
FIGURE 6 is across-sectional view taken along line 6-6 of FIGURE 1.
FIGURE 7 is a cross-sectional view taken along line 77 of FIGURE 1.
FIGURE 8 is a side elevational view of a modified form of the mechanical attachment for attaching the terminal to a conductor.
FIGURE 9 is a cross-sectional view of the terminal attachment of FIGURE 8.
FIGURE 10 is a cross-sectional view taken along line 1010 of FIGURE 9.
FIGURE 11 is a cross-sectional view taken along line 11-11 of FIGURE 5.
FIGURE 12 is an elevational view of a sheet metal blank from which the terminal of FIGURE 1 is formed.
.The terminal illustrated in FIGURE 1 is a spade type terminal that is adapted to be formed from sheet metal,
usually of brass or copper. The terminal 10 consists of a terminal end portion 11 adapted for attachment to an electrical appliance. A ferrule portion 12 i provided for mechanical attachment to the stranded conductor 13 that has any conventional insulation covering 14 thereon. Only the stranded wire conductor 13 is disposed within the ferrule 12.
The ferrule portion 12 which is mechanically crimped or clamped upon the conductor 13 is initially formed as 3,032,602 Patented May 1, 1962 "ice the U-shaped trough arrangement shown in FIGURE 3,
consists of a bottom wall portion 15 that is generally flat or planar, as more specifically shown in FIGURES 5, 6 and 7. From the bottom wall portion 15, there rise opposite side wall portions 16 and 17 from the sides of the trough. The side wall portion 16 terminates in the upper edge portions 18 and 19 that are spaced apart by an upwardly extending ear 20 that is integral with the side wall portion 16.
The side wall portion 17 terminates in an upper edge portion 21 that is spaced between a pair of ears 22 and 23 that extend upwardly relative to the edge portion 21 of the side wall 17.
As will be seen from FIGURES 3 and 12, the cars 22, 20 and 23 are arranged alternately on opposite sides of the through-like ferrule portion so that the ears 22 and 23 substantially transversely align with the edge portions 18 and 19 respectively of the wall portion 16 whereas the ear 20 of the wall 16 substantially transversely aligns with the edge portion 21 of the opposite wall 17.
.When a conductor 13,having the insulation 14 is to be attached to a terminal 10, the one end of the conductor 13 is stripped of insulation, as shown in FIGURE 3, and the bared end of the conductor 13 is positioned within the ferrule portion 12 of the terminal and supported upon the bottom wall portion 15 thereof. The bottom wall portion 15 of the ferrule is supported upon an anvil or lower die 25. An upper die 30 has a formed recess 31 therein adapted to slide down over the outer surfaces of the walls 16 and 17 of the ferrule 12. The recess 31 of the die 30 has a contoured upper surface consisting of the arcuate wall portions 32 and 33 that are formed inwardly from the outer walls 34 and 35 of the recess 31, the arcuate wall portions 32 and 33 meeting in a sharp edge 36.
When the upper die 30 is moved downwardly upon the ferrule 12, the ears 22, 20 and 23 are curled inwardly along an arcuate path controlled by the arcuate surfaces 32 and 33 of the die 30. While the ears are the first portion of the ferrule to move through the arcuate path, yet the upper edge of the portions 18, 19 and 21 of the wall portions 16 and 17 also follow the arcuate path controlled by the walls 32 and 33 of the die until the ferrule is closed and fully crimped or clamped upon the stranded conductor 13, as shown in FIGURE 4.
As more specifically shown in FIGURES 5 and 7, the ears 22 and 23 of the wall portion 17 curl inwardly until the'end surfaces 40 and 41 of the respective ears are pointed toward the inner surface of the bottom wall 15 of the ferrule, these end surfaces 40 and 41 of the respective ears being spaced from the inner surface of the bottom wall 15 and bear against strands of the conductor that are retained between the cars 22 and the wall 15. Also, the ears 22 and 23, when curled inwardly from the position shown in FIGURE 3 to that shown in FIGURES 5 and 7, encompass certain of the strands of the conductor and retain the strands between the respective ears and the side walls'17.
With the ears 22 and 23 being disposed in alternate arrangement relative to the ear 20, when the edge surfaces 42 and 43 respectively of the edges 18 and 19 of the wall 16 are curled inwardly, these surfaces 42 and 43 engage the outer surfaces of the cars 22 and 23 re- Similarly, when the ear 20 of the wall 16 is curled intudinally extending serpentine wardly, as shown in FIGURE 6, the end surface 45 thereof bears upon strands of wire between the ear and the bottom wall of the ferrule. Also, the edge portion 21 has the end surface 46 thereof engaging the outer surface of the ear 2b to close the ferrule longitudinally, as more specifically shown in FIGURE 1. The cars 22, Ztl and 23 are thus disposed in substantial longitudinal arrangement, as shown in FIGURE 11 to provide a longitudinally extending portion which bears against strands of the conductor. 7
When the ears 22, 2d and 23 are curled inwardly simultaneously by downward movement of the die 36, these cars follow a sweeping path, and because of their alternately arranged positions engage the strands of the conductor 13 beyond the longitudinal center line of the conductor at their initial engagement with the conductor and then sweep backwardly toward their respective side walls so that at least some of the strands in the conductor 13 are imparted with a longitudinally extending serpentine bend, as shown in FIGURE 11, which provides a crimp in the wire strands which resists longitudinal pull out of the Wire from the ferrule. Also since the ferrule is crimped tightly against the strands of the conductor, there is a cold working of the strands of the conductor which compress or forge the strands into a relatively solid mass within the confines of the ferrule so that the strands as encompassed by the ferrule will be substantially closed against entry of air into the area of mechanical attachment of the ferrule to the conductor and thereby reduce the rate of oxidation of thewire strands which maintains a low electrical resistance factor between the conductor and the terminal over an extended period of time. 7
In FIGURES 8, 9 and 10, there is illustrated a slightly modified form of ferrule in which the bottom wall portion 15a is provided with a raised portion 50 that extends into the interior of the trough of the terminal. This raised portion is substantially transversely aligned with the ear 20a and the edge portion 21a of the ferrule. Thus, when the ferrule of FIGURE 8 is crimped or clamped upon the conductor 13a, the raised portion 50 causes a longitudinally extending serpentine bend or crimp in the conductor 13a which provides resistance to pull out of the conductor from the ferrule, this longibend being normal to that illustrated in FIGURE 11 so that, whenthe terminal of FIGURES 8, 9 and 10 is used, there will be an added resistance to pull out of the conductor from the terminal.
It is to be understood that the foregoing description is'directed to preferred embodiments of the invention and will be forthcoming under ideal conditions. In production activities, however, one or more of the conditions required to obtain optimum results are sometimes not present. Cross sections taken through this type of crimp sometimes show that the ends 42, 43 and 46 of the ears I8, 19 and 21 respectively do not make actual contact with the facesof the opposed cars 22, 23 and as shown'in FIGURES 5,6 and 7. Furthermore, it has sometimes'been noted that cross sections of said crimps show the ends 40, 41 and 45 of the ears 22, 23 and 20 respectively 'in direct contact with the bottom wall of the ferrule 15, rather than spaced therefrom by strands of the wire conductor.
These deviations from optimum conditions are created by several factors.
In production activities, it is economreally necessary to utilize a single crimping die and a single ferrule for at least two gauge sizes of wire. For this reason, the same ferrule is generally used for a #14 and a #16 gauge wire while another size ferrule and crimping die will be used in connection with a #18 and a #20 gauge wire, etc. This means that the ferrule will either be dimensioned to properly crimp on one wireor the other of the two sizes or the ferrule will be dimensioned as a'compromise between the exact dimensions for either of the two sizes. Under these conditions, it
7 often do not separate equally.
rather large bundle will fall under there is a tendency looser as the surfaces of Wall portions 32 and .33 of In these instances, as soon as wear is apparent, the dies must necessarily be reset is apparent that the crimp, in certain instances, will not be the optimum crimp for the given wire size.
Similarly, since the wires being crimped are stranded wires, the number of strandshave a marked bearing on the form of the crimp. in this connection, as the ears bend over into crimping engagement with the wire, the
, several strands separate and it has been found that they In some instances, a one ear and relatively few strands will be left for the other car to engage. This means that the ear engaging the large bundle will not fold to its proper position but that it will become deformed and the wire therebeneath will be deformed heavily while the other ear will have no resistance toward forming due to the fact that insufficient wire isthereunder to present any impediment to crimping. In this instance, therefore, the crimp will not be completely uniform in cross section nor will it be centered with re spect to the longitudinal axis of the terminal. The number of strands in the'stranded wire also has bearing on the crimp. This varies with the gauge size of the wire and may even be different in a given size of wire, according to the specific gauge ofv the individual strands used to make up the wire.
Another factor that contributes to deviations in the crimp is directed to the crimping dies per se. As these dies are used, the surfaces thereof begin to wear and for the crimp to become slightly FIGURE 3 begin to wear.
and/or reworked slightly in order to bring them back to their original condition.
The die variations from wear and the several other variables noted above will all have effect on the uniformity of the crimp. It is to be understood that these slight deviations from the preferred forms, while affecting the appearance of the crimp, do not affect the electrical or the mechanical efficiency thereof since, in all cases, the wire being attached to the terminal is heavily forged and tightly gripped to provide a satisfactory electrical and mechanical connection.
While the forms of embodiment of the present invention as. herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.
What is claimed is as follows:
1. An electrical connection, comprising; a connector conductor disposed longitudinally therein, one portion of the ferrule surrounding the conductor with integral ears extending from opposite sides thereof alternately and curled inwardly to dispose the ends of the alternately arranged ears in a generally longitudinal arrangement with the end surfaces of the ears positioned generally centrally of the ferrule and facing the inner bottom surface of said ferrule, the said sides of said ferrule opposite respectively to the position of the said ears having longitudinally extending straight-edged portions curled inwardly toward the said ears with the end surfaces of the said edge portions facing the outer surfaces of the said ears and contacting said outer surfaces substantially to'close thereby the ferrule longitudinally and generally centrally to effect a low resistance electrical connection.
2. An electrical connection, comprising, a connector including a ferrule having the based conductor disposed longitudinally therein, one portion of the ferrule surrounding the conductor with integral ears extending from opposite sides thereof alternately and curled inwardly to disposed the ends of the alternately arranged ears in a generally longitudinal arrangement with the end surfaces of the ears positioned generally centrally of the ferrule and facing the inner bottom surface of said ferrule, said alternate ears alternately transversely displacing strands of said conductor encompassed thereby to effect a longitudinally extending laterally disend of a stranded 3. Arielectrical connection as defined in claim 1 which 10 2,818,632
6 includes a raised portion located centrally and extending longitudinally in the bottom surface of the ferrule beneath the said ears against which strands of the conductor are forced by the ears and retained therebetween.
References Cited in the file of this patent UNITED STATES PATENTS Macy June 19, 1951 Broske Mar. 19, 1957 Hamrnell Ian. 7, 1958