US2882515A - Spiral terminal - Google Patents

Description

April 14, 1959 J. P. WATSON SPIRAL TERMINAL Filed May 23. 1955 w MR M m M mm w I A 5 w United States Patent SPIRAL TERMINAL James P. Watson, Whittier, Calif.

Application May 23, 1955, Serial No. 510,190

7 Claims. (Cl. 339-278) This invention relates to terminals, or securing posts, and more particularly to electrical terminals adapted to be engaged by flexible conductors such as wires.

In the wiring of small apparatus, such as small appliances and electronic equipment, loose ends of wire, where the wire connects from one element to the other, are most objectionable. It is accordingly an object of the present invention to provide a terminal which will eliminate loose wire ends.

In the connecting of a wire to a terminal, as in a small appliance or electronic chassis, it is customary to solder or otherwise bond the wire to the terminal. During the soldering operation, it is necessary to hold the wire firmly against the terminal, and in close quarters this procedure is often quite diificult. It is an object of this invention to provide a terminal to which the wire may be firmly secured physically, following which it may be bonded to the terminal, if desired.

It is a further object of this invention to provide a terminal having no moving parts, so that a wire may be readily engaged with the terminal with only one hand.

It is another object of this invention to provide an electrical terminal to which a wire may be connected and which provides satisfactory electric contact without the employment of solder, but which is adaptable to the application of solder if desired.

It is a further object of this invention to provide a terminal which may be readily engaged by a wire with good electrical contact between the terminal and the wire.

It is another object of this invention to provide a terminal, or securing post adapted to receive a wire and so designed that after the wire is secured to the terminal, the entire assembly is symmetrical, thereby adapting the terminal particularly well for use in confined quarters;

It is'another object of this invention to provide an electrical terminal especially suited for the reception of a sleeve of insulation over both the end of the wire connected to the terminal and the terminal itself, whereby the entire joint may be quickly and effectively insulated.

It is another object 'of this invention to provide a terminal which has a recess to receive a Wire so that the terminal assembly is not appreciably enlarged by the securement of the wire.

It is a further object of this invention to provide a terminal adapted to receive a wide range of wire sizes, thereby minimizing the number of different sized terminals which must be carried in stock.

In accordance with these and other objects which will become apparent hereinafter, preferred embodiments of the present invention will now be described with reference to the accompanying drawing wherein:

Fig. l is a view of one form of the terminal with a wire engaged therewith.

Fig. 2 is a view of the terminal of Fig. 1 without the wire in place.

Fig. 3 is a view similar to Fig. 2 and showing another form of thepresent invention.

Patented Apr. 14, 1959 Fig. 4 is a perspective view showing still another form of the present invention with a wire connected to the terminal, and

Fig. 5 is a plan view looking down on a plurality of terminals constructed according to the present invention and illustrating the particular suitability of the present invention for use in a terminal block having a plurality of terminals.

Referring to the drawing, the terminal is shown comprised of a post 11, which when the invention is employed as an electrical terminal is made of conductive material. Around the post 11 extends a spiral or helical groove 12. The groove 12 may be of any extent desired; it has been found in practice that a groove extending substantially completely around the post once, i.e., through 360, is satisfactory for most applications.

In the embodiment shown in Fig. 3, the entire post 11a is round, while in the embodiment shown in Figs. 1 and 2 only the upper portion, in which the groove 12 is located, is round, the bottom portion being square. It will be readily apparent that if desired the entire post may be made square like the bottom portion of Fig. 2, although it is preferred to make at least the upper portion wherein the groove 12 resides round. At one end, in this case the upper end, post 11 is provided with an axial bore 13 intersecting the groove 12, so that the bore 13 communicates with the groove 12 and leaves or forms a horn 14 at the upper end of the terminal. It is preferred to make the bore 13 exactly equal in diameter to the root diameter of the post 11, i.e., the diameter of the internal portion 16 formed by the base of the groove 12. However, the diameter of the bore 13 may be made somewhat larger than the diameter of the portion 16, if desired, since this would also cause an intersection between the bore and the groove and allow the bore to communicate with the groove as shown in the drawing.

Adjacent the bottom or other end of the groove 12 and generally transverse of the groove, is provided an anchor hole 17. In the embodiments shown in Figs. 2 and 3 the anchor hole 17 extends obliquely into the post 11 and is positioned at the bottom end of the groove 12.

The terminal thus described is adapted to receive a wire 18, the end of the wire being placed in the anchor hole 17 and the wire then being spiraled around the terminal in the groove 12, as shown in Fig. 1. At the upper end of the terminal, the wire passes or is tucked under the horn 14, so that the wire leaves the terminal substantially axially thereof.

The wire 18 may be either solid or stranded as shown in Fig. 1. The diameter of the wire is preferably chosen to be substantially equal to or only slightly smaller than the width of the groove 12, so that the wire substantially fills the groove. In passing at least once completely around the terminal, as shown in Fig. 1, the wire is caused to engage the post 11 with good electrical 'contact, such contact being provided not only at the bottom of the groove, i.e., the root diameter of the post 11, but also at each side of the groove, assuming that the wire diameter is, as preferred, approximately equal to the width of the groove 12.

The insertion of the end of the wire 18 into the hole 17 eliminates any loose ends which might be troublesome and which might stick out to engage an undesired conducting part and cause a short circuit. After the wire has been secured physically to the post 11 as shown in Fig. 1, solder may be run in through the crevices between the wire and the post, thereby enhancing the physical and electrical bond between the'post and the wire; although in many cases it has been found that secure ment both electrically and physically is adequate without 3 any solder or other bonding material. The electrical securement or contact is effected by the large aggregate area of contact between the wire and the post, as explained hereinbefore; and the physical securement is effected by the anchoring action of the end 'of the wire in the transverse hole 17, by the 'snubbing action of the wire 18 as it is wound around the post 11 in the groove 12, and by bending of the wireas it passes under the horn 14 and departs axially from the post 11. All of these factors contribute to provide a firm physical securement between the wire 18 and post 11 which resists a considerable separating pull between the wire and thepost. In order to minimize space requirements and at the same time fortify the snubbing action of the groove 12, it is preferred to make the depth of the groove 12 at least equal to one-quarter of the thickness or outer diameter of the post 11, that is, the depth of the groove 12 is preferably at least equal to one-halfof the diamtiter 'of the internal portion 16.

The other or bottom end ofthe post 11 ma take several forms and functions. Fo'r'example, the post 'll may be anchored in or formed integral with a conducting base or plate 19 which forms a terminal block 'to which the wire 18 is electrically connected. The base 19 may, if desired, have a plurality of 11 posts thereon, as shown in Fig. 5, in which case the base constitutes a common terminal for several wires, each of which is secured to an individual post 11. The post 11 may be continued through on to the opposite side of the base 19, and be duplicated so that wires may be connected to both sides of the base.

The base 19, if desired, may be made of insulating material, both in the form shown in Fig. 4 and the form shown in Fig. 5. To complete the circuit from the post 11, the post is preferably passed through to the under side of the insulating base 19 where it is duplicated and another wire is taken off in similar manner. Thus two wires may be connected together through the intermediacy of a single terminal post 11 extending on both sides of the base 19. It will be readily seen that when an insulating base 19 is used the circuit may be completed by means other than a duplication of the post 11, such other means taking any form of terminal desired.

Where a base 19 is employed, either conductive ornonconductive, it may be desirable in some instances to provide the anchor hole in the base 19 rather than in the post 11, as shown at 17a. In either event, however, the hole 17 or 17a as the case may be, is preferably transverse of the end of the groove 12, so that a bending of the wire 18 at the juncture is effected, thereby enhancing the physical securement of the wire to the terminal. Where a plurality of posts 11 are provided on a single base 19, as shown in Fig. 5, it is preferred to place the several anchor holes 17a facing toward the outside of the base 19, thereby eliminating any danger of accidental contact between wires connected to the various terminal posts 11. This expedient is particularly desirable where the base 19 is of insu lating material.

An especially strong securement may 'be effected by making the post 11 of two parts. One part is the internal portion 16, and separate from this part is the spiral or helical portion 21, both of the parts 16 and 21 being either connected to or formed integrally with the bottom portion of the post 11 or to the base 19. Where this structure is employed, the groove 12 is made slightly smaller than the wire 18 which it is to receive; thus as the wire 18 is pressed into the groove, the helical portion 21 is caused to extend longitudinally slightly, and to this end, it is preferred to make the portion 21 of a somewhat springy material. The separation between the parts 16 and 21 permits longitudinal resilient springing of the helical portion 21, and the resiliency of the portion 21 provides a longitudinal clamping action against the wire 18 and firmly secures it in place without any requirement of soldering or other bonding.

Where the parts 16 and 21-ar'e made separate as de- 4. scribed above, the diameter of the part 16 is made sulficiently smaller than the internal diameter of the helix 21 to permit the necessary longitudinal movement of the helix 21 without excessive clearance.

If desired, the internal part 16 may be completely eliminated, this being equivalent to making the axial bore 13 the full height of the helical portion 21. In this event, care must be taken when pressing the wire 18, which is slightly larger than the groove 12, into the groove, to insure that it does not pass completely into the bore 13. In order to insure against this, it is preferred in such as case to form the groove 12 with outwardly diverging sides so as to eifect a wedging action as the wire is pressed in and prevent its passage completely into the 'bore 13.. After the wire 18 has been secured to the terminal post 11, a sleeve of insulation 22 may, by virtue of the axial departure of the wire 18 from the post 11, be readily slipped over the juncture, as shown in Fig. 1. This is made particularly facile by the recessin'g of the wire 18 in the "groove 12, whereby the overall size of the 'terminal-and-wire assembly is not increased over'that of the terminal alone.

While Fig. 1 shows astranded wire 18 which 'is large enough to substantially fill the groove 12, it has been found in practice that the snubbing action is sufficient to retain even a single strand of the wire. Thus a given post 11 can accommodate a wide range of Wire sizes with resulting saving in the number of different sized terminals which must be kept in stock.

While the instant invention has been shown and described herein in what is conceived to be the most practical and preferred embodiments, it is recognized that departures may be made therefrom within the scope of the invention which is therefore not to be limited to the details disclosed herein, but is to be accorded the full scope of the claims.

What is claimed is:

1. Electrical terminal comprising a post made of conductive material and having a helical groove extending therearound and adapted to receive a Wire, said terminal including a dead end anchor hole positioned adjacent one end of said groove into which the end of said wire may be inserted, said post having an axial bore at the opposite end of said groove communicating with said groove along the length of said bore, through which said wire may axially enter said groove at the bottom of said bore, said helical groove overlapping said bore a sufficient extent to provide a born to engage the wire.

2. Electrical terminal comprising a conducting post having a helical groove formed therein, said groove being of a depth at least equal to one quarter of the thickness of said post, said post having at one end an axial bore communicating with said groove along the length of said bore, said helical groove overlapping said bore a sutficient extent to provide a horn to engage a wire, said terminal being adapted to receive the wire wound in said groove and departing from the terminal through said axial bore.

3. Electrical terminal comprising a conducting post having a helical groove formed therein, said post having at "one end an axial bore communicating with said groove along the length of said bore, said helical groove overlapping said bore a suflicient extent to provide a born to engage a wire, said terminal being adapted to receive the wire wound in said groove and departing from the terminal through said axial bore.

"4. Electrical terminal comprising a base member, a cylindrical post secured to said base member, said post having helical groove means for receiving a wire secured to said terminal, said groove means having adepth at least equal to one quarter of the outer diameter of said post said terminal having a dead end anchor hole adjacent the base end of said helical groove means for receiving the end of a wire, said post having an axial bore atthe-opposite end of said groove means communicating with said groove means along the length'of -s'aid bore, said helical groove means overlapping said bore a sufiicient extent to provide a horn to engage the wire, said wire being adapted to be placed in said bore and groove for physical securement with good electrical contact.

5. Electrical terminal comprising a conductive post having a helical groove adapted to receive a wire, and an axial bore intersecting said groove, said helical groove overlapping said axial bore at least one-half a turn, whereby said bore communicates with said groove to form a horn under which the wire may be tucked as it engages the terminal axially, said terminal including an anchor hole positioned adjacent the end of said groove opposite said horn and generally transverse of said groove into which the end of the wire may be inserted.

6. Terminal comprising a post having a helical groove extending therearound adapted to receive a wire, an axial bore at one end thereof extending thereinto for only a portion of the longitudinal extent of said groove, intersecting said groove and having a diameter at least as great as the internal diameter of said groove, said groove communicating with said bore along the length of said bore, said groove overlapping the bore a sufficient extent to provide a horn under which the wire may be tucked as it axially enters the groove from the bore.

7. Electrical terminal comprising a post made of conductive material, having a helical strip surrounding a core, the turns of the helical strip spaced to provide a wire-receiving helical groove, said core terminating short of one end of said post a suflicient distance to form an axial bore, said axial bore communicating with said helical groove along the length of said bore, whereby said helical strip provides a horn to engage a wire passing from said bore into said groove.

References Cited in the file of this patent UNITED STATES PATENTS 670,552 Brown Mar. 26, 1901 1,122,351 Adickes Dec. 29, 1914 1,584,533 Hands May 11, 1926 1,875,241 Idank Aug. 30, 1932 FOREIGN PATENTS 5508/27 Australia Jan. 11, 1927 104,417 Switzerland Apr. 16, 1924 220,731 Great Britain Aug. 26, 1924

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