US2942232A - Electrical terminal - Google Patents

Description

June 21, 1960 L. 1'. KNOCKE 2,942,232

ELECTRICAL TERMINAL Filed June 25, 1956 INVENTOR. A0205 7' Kvacie Un ed Sta s. P t n V 2,942,2sz

Louis 'r. Knocke, s s-is Putnam, Birmingham, Mitt.

Filed June 25, 19,5 sen. stdssaszs '1 Claim; C1. saw- 25s This invention relates to terminals for electriccenductors such as may be used in various electrical circuits of an automobile, truck, or other vehicle or machine or in general. wherever a removable electric wire connection is needed.

It will be easily recognized that the most important requirement of an electrical connection, apart from its capacity to properly transmit current, is that it maintain The invention is illustrated in the accompanying drawings in which: I

Figure 1 is a plan-view partly broken away of a terminal block to which three electrical conductors having terminals constructed in accordance with my invention are attached;

Fig. 2 is a cross section along the line 2-2 of Fig.1;

Fig. 3 is a plan view of the blank from which a preferred form of electrical terminal in accordance with my invention is constructed;

Fig. 4 is a side elevation of the blank shown in Fig. 3;

Fig. 5 is a side elevation of the terminal after it has been formed from the blank but prior to its attachment to an electric conductor; Fig. 6 is a bottom plan view of the structure shown in Fig. 5; 1 1

Fig. 7 is an end elevation taken from the left of Fig. 5;

Fig. 8 is a cross section taken along the line 88 of Fig. 6; and

Fig. 9 is a cross section similar to Fig. 8 but showing a slightly modified form of the invention.

In Figure 1 the non-conducting block 1 is typical of a member to which electrical conductors can be physically connected. It has a series of threaded posts 3 mounted therein and on the posts are nuts 5. Embedded in the top of the member 1 around the posts 3 may be a metaltory for two reasons, viz., (1) itincludes the lock washer as an additional part which in itself adds expense to the assembly and which requires additional labor to introduce as part of the assembly and (2) experience has shown that the lock was'hers'are not fully satisfactory, since theydo not maintain tightness whenside loads are applied to the terminal or conductor and since they add no elasticity to the assembly which'can compensate for a' decrease-in grip thickness and a loss of tension :in' the post. v l

-In myinvention I eliminate the lock washer as'an extrapart andfthus overcome the trouble of assembling it and .re'ducef 'to' some extent the total cost of the assembly. When'it. is"realized'thatinillions of such connections; are made'each-year in the production of one make of automobile, for example, it will be appreciated that very small savings per connection can total up to very substantial cost reductions on a yearly basis.

In my invention I intentionally avoid the lock washer notion of biting into the mating surfaces so as to prevent their relative movement. Instead, my electric terminal is based on the principle of increasing the elasticity of the assembly and I do this in such' a way that the force of friction preventing rotation of the electric terminal is less than the frictional torque in the threads of the binding post meanssuch as a nut or screw. As a result the assembly does not tend to come loose if there is movement of the electric terminal. A further advantage of my invention is that it will automatically compensate for embedding, cold flow, or deformation of the various elements of the assembly, and the resultant decrease in its grip thickness, without any significant reductioniin the elastic forces holding the assembly in a tight condition.

In my invention I contemplate the use of a metal electric terminal in which the outlet end is conical and preferably comprises bent over washer shaped portions each of which are conical with aligned apertures located on the axis of the conical sections to receive the binding post.

lie conductor 7. These parts are standard and formno part of the present invention. It should also be noted that it is immaterial to the present invention what the precise construction and arrangement of these elements are. For example, the post? may be turned upside down so that its headed end would engage an electric terminal and its lower end threadrinto a suitable tapped opening provided in the member, 1. It will thus be assumed throughout the specification and claims that the word nu is to be interpreted broadly to comprehend any threaded means for holding the electric terminal in place on the member 1 and it therefore clearly includes areversal of the screw 3 so that the head thereof bears upon theterminal. 4

' The insulated electric wires for the conductor 9 are electrically and'physically connected to the post3 by means of the metal terminals 11, theouter ends of which areconstructed in accordance with my invention. 1 g .1 The terminals 11 may be secured by any suitable means to the conductor 9 and I have shown the con- I ventional usage of overlapping arms "13 which are clamped to the insulation of the conductor 9 and the turned over arms 15 which are clamped to the bared wire of the conductor 9.

The terminal 11 may most advantageously be stamped and formed from a flat sheet of suitable metal by progressive die techniques and the blank will appear as shown in Figure 3. It comprises an inner annular section or ring 17 and an outer annular section 19, the inner section 17 being connected to the arms 15 by a reduced section or neck 21 and to the outer ring 19 by neck 23. The rings 17 and 19 willbe conically formed with flat sides as seen at 25 in Fig. 4. The ring 19 is folded back above the section 17 so that the aperture 27 thereof is above and in alignment with'the aperture 29,

these apertures obviously fitting over the post 3.

The sides 25 of the rings 17 and 19 are preferably flat and conical or inclined as seen best in Fig. 8 and arranged so that the smaller diameters or apices of the cones are on the outside. When the terminal is mounted on the post 3, the bottom of ring 17 will engage the conductor 7 and the top of ring 19 will engage nut 5, though it will be appreciated that this can be reversed within the broad purview of the invention. Before the nut 5 is tightened there will be only circular line contact between the ring 17 and conductor 7 and between'ring 19 and nut and this condition will be maintained until the nut 5 is tightened completely so that the cones 25 are collapsed and the rings r17 and 19 flattened to provide .a large area of contact between the terminal, the nut Sfland the conductor 7. If desired, 'the,bent,over ring 19 may be formed so that it is spaced slightly above the .lower ring .17 asshown by the gap 31 to provide increased resilience. The neck or hinge, section 23 may also be provided with a radius as shown at 33 to facilitate folding of the one ring upon the other and to minimize the possibility of fracture upon repeated deflections of the terminal. The extruded edges 35 of'the holes 27 and 29 will cut through surface film on contacting parts and provide better electrical connection. I

As can be seen by comparing Figures 2 and .8, the .unstressed thickness of the terminal 11 is fairly great and that in attempting to return 'to this height from the'fiattened condition of Fig. 2 it will exert a continuou'sforce on the threads of the stud 3 throughout this height. The over-all height of the terminal is thus sufiicient 'to accommodate any embedding of edges of the terminal into the conductor 7 or the nut 5 without substantial or significant loss of elastic force holding the assembly tight. In the flattened position of Fig. 2 it will be seen that there is a substantial area of friction between the terminal 11 and the nut 5 and the conductor 7, both of which tend to resist rotation of the terminal 11 relative to the nut 5 or the conductor 7. The magnitude of the frictional resistance depends upon the areas of contact and upon the compressive forces in the sections 17 and 19 as they tend to expand to their unstressed position. At the same time there is a corresponding force acting on a somewhat smaller area of contact between the threads of the nut'7 and the post 3. As a consequence, when a side force is placed on the terminal 11 in a direction to unscrew the nut 5 the friction holding 'thering 27 to the nut 5 will be somewhat greater than the friction holding the nut 5 to the threads of post 3 and the nut will move relatively to the threads and tend to unscrew, thus reducing the compression on the terminal 11.

However, a very slight reduction in compression by nut '5 on the terminal 11 will allow the terminal to expand a slight amount and immediately the flat area contacts of the terminal will change to circular line contacts with the conduct0r7 and the bottom of the nut 5. 'Consequently, there will now be less friction between the terminal and the nut than there will be between the nut and the post '3 .so *that'further force on the terminal 11 will merely cause it to rotate about the axis of the post 3 but will not cause any loosening of the nut 5 on the post. Thus tightness is maintained with this terminal in sharp contrast to what occurs in standard types of connections of this sort wherein side loads would continue to unscrew the nut and thus eventually loosen the assembly so that the electrical connection is destroyed. It will be noted that the contacting portions in my terminal are annular and continuous and present no radial edges which would act as ratchet teeth to prevent pivotal movement of the terminal about the axis of the post 3.

Itwlill now be recognized that my design of electrical terminal fulfills three basic-requirements .of a highly effective locking or non lo'osening nature. First, it adds elasticity to the assembly. Second, it prevents any substantial decreases in grip thickness by providing large uninterrupted bearing areas. Third, it prevents the nut from turning and loosening of the assembly when the terminal is moved angularly.

I claim: 1 In an i electrical terminal adapted to connect a wire to a threadedbinding ,post of the type protruding from'a fiat-surfaced conductor and having a flat-surfaced securing nut, an elongated metal member, electrical conductor connecting means at one end of said member for securing a wire thereto, a first annular terminal portion of rela'- tively "flat conical shape formed at the other end of said member, a reversely bent neck of narrower width than said first terminal portion and formed at the outer edge thereof, and a second annular terminal portion of relatively flat conical shape overlapping said first terminal portion, the bases of said terminal portions facing each other, the cone .inclinations o'f said terminal portions being such that tightening of said nut will cause said. portions to flatten against each other and change from line contact to surface contact with both said conductor and said nut without exceeding the elastic limit of the metal, whereby slight loosening of said'nut will permit said terminal portions to expand, and reassume line contact with said conductor and nut.

References Cited in the file of this patent UNITED .srATEsI PATENTS

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