US2558851A - Fastening means for switch terminals - Google Patents

Description

July 3, 1951 E. N. JACOBI FASTENING MEANS FOR SWITCH TERMINALS Filed June 2 948 Patented July 3, 1951 11,-1.2:

FASTENING MEANS FOR SWITCH TERMINALS Edward N. Jacobi, Milwaukee, Wis., assignor to Briggs &

Stratton Corporation, Milwaukee,

Wis., a corporation of Delaware Application June 24, 1948, Serial No. 35,047

5 Claims.

This invention relates to electrical switches and refers more particularly to switches of the typ having terminal studs with portions thereof providing stationary switch contacts.

In switches of this type the terminal studs are usually embedded in an insulative terminal plate which closes the rear of the switch case and the stems of the studs project rearwardly from the plate and are adapted to have electrical conductors connected to them. The heads of the studs are commonly made larger than the remainder thereof and they are usually recessed into wells in the inner face of the terminal plate, having their tops exposed and substantially flush with theinner surface of the plate to provide stationary contacts adapted to be engaged or bridged by a movable contactor in the switch case.

Ordinarily the terminal plate is provided with holes into .each of which a stud is driven with a press fit, and the shank portions of the studs under their enlarged heads are knurled to cooperate with the material of the plate in securing the studs in the plate and against rotation relative to the plate. The free end portion of the stem of each stud, which projects rearwardly from the terminal plate, is usually threaded to receive one or more terminal nuts by means of which a wire connector is secured to the rear of the stud.

Frequently switches of the type under consideration have a cylindrical metal case the rear rim of which is clinched over the periphery of the terminal plate to hold the plate assembled at the rear of the case. In such switches, a plurality of washers is customarily placed on each stud, between the rear face of the terminal plate and the terminal nuts, in order to space the conductors secured to the terminals a distance outwardly Of the plane of the rear edge of the switch case, thereby minimizing the possibility of short circuiting between the terminal wires and the switch case. This past practice of using a number of washers in combination with a pair of terminal nuts is obviously unhandy and costly, and therefore objectionable.

Moreover, in assembly of the switch the washers are first placed on the studs and one terminal nut is then threaded onto each stud, being tightened by means-of a power wrench. The power Wrench operator must exercise a high degree Of caution to prevent the application of excessive tightening torque to the nuts, since the knurling on the shanks is insufficient to prevent rotation of the studs when excessive turning force isapplied to them and the knurled surface would tend to chew up the sides of the holes in the.

terminal plate, thus enlarging them. Since it is extremely difiicult for the operator of a power wrench to determine the proper amount of tightening torque to apply to the terminal nuts, the terminal studs are frequently torn loose from the plate in which they are seated, necessitating the scrapping of an entire switch just at the point where its assembly is about to be completed.

It is therefore an object of this invention to provide simple and inexpensive means for anchoring terminal studs to the terminalplate ofan electric switch, which means will provide a rigidly secure nonrotatable joint between the studs and the plate.

More specifically it is an object of this invention to provide locking means for the terminal studs of an electrical switch capable of clinching. and compacting the insulative material surrounding the knurled portion of the terminal stud and forcing it toward the stud when increased tightening torque is applied to the terminal nut.

Another object of this invention resides in the provision of convenient and inexpensive locking means for terminal studs which is .also useful for spacing the wire or other conductors secured to the studs asubstantial distance beyond the plane of the edge of the switch case.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being understood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawing illustrates one complete example of the physical embodiments of the invention constructed according to the best mode so far devised-for the practical application of the principles thereof, and in which:

Figure 1 is a side 'elevational View of a lock switch having terminal studs secured in place on the terminal plate by meansof the device of this invention, portions being shown cut "away;

Figure 2 is a detail perspective view showing the terminal plate of an electrical switch and-its associated terminal studs and their respective holding devices, with twoof .the studs assembled to the terminal plate and the third prepared for assembly thereto;

Figure 3 is a longitudinal sectional view showing .a terminal stud mountedin a terminal plate and secured by 'means of the device of this invention;. and

Figure 4 is an enlarged cross-sectional view of a modified form of the device of this invention.

Referrin now more particularly to the accompanying drawing in which like numerals designate like parts throughout the several views, the numeral designates generally the case of an electrical switch. Theswitch here shown by way of illustration is part of-an ignition switch-lock assembly of the type adapted to be mounted on the instrument panel 6 of an automobile. The bore 1 of the case opens to the rear of the case through a counterbore 8, and an insulative terminal plate 9 is seated in the counter-bore to close the back of the case. the terminal plate is secured in place, with its As is customary,-

front face abutting the shoulder ll defined by the bottom of the counterbore, by clinching the rear end or rim l2 of the case around the rear face of the terminal plate, at the periphery thereof.

- A plurality of terminal studs ID are embedded in the terminal plate, and the stems I 3 of the studs, which protrude rearwardly from the terminal plate, are threaded to receive one or more terminal nuts M. The head l5 of each stud is enlarged and is recessed into a well in the inner face of the terminal 'plate so that its top I5 is exposed and substantially flush with the front surface of the plate to form one of the stationary contacts of the switch. These contacts are engageable by a movable bridging contactor I6 inside the lock case actuated by means of a conventional key operated lock cylinder (not shown) rotated by means of a key ll.

The medial portion l8 of each stud, from a point directly back of the head to a point a short distance to the rear of the terminal plate, is provided with knurling; preferably in the form of longitudinal ridges and grooves. Since the aperture in the plate through which this knurled portion of the stud passes is of such a size as to provide apress fit for the stud, it will be seen that these ridges in effect provide a series of teeth which cooperate with the material around the aperture to preclude rotation of the stud.

It will also be seen, however, that if any considerable turning force is applied to the stud these teeth will chew or scrape the sides of the aperture, enlarging it and permitting the stud to turn virtually unhindered.

Inprevious devices of this character a group of washers was'slipped over the stem of the stud, and a terminal nut threaded down over them to secure the stud in place against longitudinal shifting, a second terminal or jam nut being used to secure the conductor to the stud. Frequently, as noted above, the installation of this first nut resulted in the application ofsufiicient torque to the stud to damage the terminal plate, necessitating discard of the switch.

By the present invention, however, a spacer sleeve I9 is provided for each stud. Each of the sleeves is press fitted over the knurled medial portion I8 of its stud and has its front end in engagement'with the rear face of the terminal plate.- The rear of the sleeve is provided with an annular'shoulderwhich provides a bearing for a lock washer. 2| interposed between the sleeve I9 andjthe terminal nut M, or preferably a seat for a terminal conductor (not shown).

It will be understood that the lock washer may be omitted in cases where two terminal nuts are to bethreadedonto each stud, and the in-.

ner terminal nut permitted to abut the shoulder 20 directly, or the terminal conductor may be interposed between a single terminal nut l4 and the shoulder 20 but the use of a lock washer is obviously desirable since it tends to prevent the nut from loosening under the influence of vibration.

The front end portion of each of the sleeves is outwardly flared, as at 22. This flared portion in effect forms a hollow cone on the front end of the sleeve which is adapted to be pressed into the rear face of the terminal plate as the sleeve is urged forward in consequence to tightening of the nut 14; and as the sleeve moves forwardly this cone compacts the material of the terminal plate radially inwardly, into the grooves in the medial knurled portion I8 of the stud. In this manner the stud is tightly restrained against turning by the cooperation between the compressed material of the plate and the ridges on the stud, and the application of increased tightening torque to the nut [4, as it causes the nut (and thus the sleeve) to move forwardly, will increase the compacting effect of the fiareand thereby cause the stud to be more securely held against rotation.

It will also be obvious that the provision of the sleeve l9 eliminates the need for spacer washers to hold the terminal conductor spaced from the plane of the rear rim l2 of the case, particularly where it is not desired to use a check nut between the rear face of the plate and the conductor. 1

While the sleeve alone, by virtue of its press fit over the knurled portion of the stud, is normally adequate to hold the stud in place, even without the use of a securement nut, itmay in some cases be desirable to secure the stud. more tightly in. place to insureagainst any tendency for it to come loose when the conductor is dis-i connected from it, and in that event the modification illustrated in Figure 4 may be employed. In this the sleeve is squeezed together ,at diametrically opposite sides, as at 23, by means of a die, the sleeve and stud being both deformed, with the material of thesleeve being embedded in the knurling of the stud. In this modification the cone shaped front portion 22 also servesv to compact the material of the terminal plate into secure binding engagement with the knurling on the medial portion of the stud.

From the foregoing description togetherwith the accompanying drawings it will be readily apparent that this invention provides a spacer sleeve for a terminal stud of a switch of the character described which insures that a conductor secured to the terminal stud will be spaced sufiiciently far from the plane of the rear rim of the switch case to preclude short circuiting engagement therewith; and that the spacer sleeve of this invention secures the stud in position in the terminal plate before the securementnut is put in place thereon during assemblyof .the switch and holds the stud against undesired rota-- tion during installation of the nut even though excessive tightening torque may be applied thereto.

I claim:

1 In an electric switch: an insulative terminal plate; a-terminal stud having an enlarged head exposed at the front face of the platetopr'ovide one of the fixed contacts for the switch and havinTg its stem extending through a close fitting aperture in the plate to project rearwardly from the rear face of the plate, the portion of .the stem which passes through the plate -'-bei'ng knurled and the rear portion thereof being threaded to receive a terminal nut for securing a conductor to the terminal; and means for radially inwardly compacting the material of the terminal plate into binding engagement with the knurling on the terminal stud so as to preclude rotation of the stud in its aperture upon tightening of the terminal nut, said means comprising a tightly fitting sleeve surrounding the knurled portion of the stem of the terminal stud and having its rear end so disposed that the sleeve will be driven forwardly upon the stud when the terminal nut is tightened, and an outwardly flared front end portion on said sleeve engaged with the rear face of the terminal plate and adapted to be forced into the terminal plate upon tightening of the terminal nut.

2. In an electrical switch of the character described: an insulating terminal plate; a terminal stud having an enlarged head exposed at one side of the terminal plate and having its stem projecting through a close fitting aperture in the plate to the opposite side thereof to receive a terminal nut, the portion of the stem adjacent to the head of the stud being longitudinally grooved;

and means for precluding rotation of the terminal stud in consequence to the application of large tightening torque to the terminal nut, said means comprising a sleeve-like spacer on said stud adjacent to said opposite side of the terminal plate so as to be interposed between the plate and a terminal nut on the stud, said spacer having a wire supporting shoulder at its end remote from the plate and having an annular outwardly flared end portion pressed into said opposite face of the terminal plate and adapted to compress the material of the plate radially inwardly into the grooves in the stud in consequence to an increase of the force with which said flared portion is pressed into the terminal plate as a result of tightening of the terminal nut. 3. In an electric switch: an insulative terminal plate; a terminal stud having an enlarged head at the front face of the terminal plate and a threaded stem projecting from the rear face of the terminal plate and adapted to have a nut threaded thereon to secure a conductor to the terminal stud, the medial portion of said stud passing through a closely fitted aperture in the plate and having a plurality of longitudinal grooves which define ridge-like teeth adapted to cooperate with the material of the plate to preclude rotation of the stud in the plate; and means to preclude chewing of the plate by the teeth of the stud and turning of the stud in the plate in consequence to tightening of a nut on the stud, said means comprising a spacer sleeve telescoped over the rear of the stud, said sleeve having an annular shoulder at its rear end against which a conductor connected to the stud is adapted to be supported for spacing from the plane of the rear face of the plate, said sleeve also having an annular outwardly flared front end in engagement with the rear face of the plate and adapted to compress the material of the plate radially inwardly into said grooves in the medial portion of the stud upon forward movement of the sleeve.

4. In an electric switch: an insulative terminal plate; a terminal stud having an enlarged head at its front end exposed at one face of the plate and having its rear end portion projecting from the other face of the plate and threaded to receive a nut adapted to secure a conductor to the terminal stud, the medial portion of said stud ex tending through a close fitting aperture in the plate and being ridged to cooperate with the material of the plate to preclude rotation of the stud; and means for precluding rotation of the stud in consequence to excessive tightening of the terminal nut, said means comprising a sleeve telescoped over tie medial portion of the stud, a portion at the front end of said sleeve outwardly flared and pressed into engagement with said other face of the plate to compress the material of the plate radially inwardly into rotation-precluding engagement with the ridges of the stud, said sleeve also having a shoulder at its rear against which a conductor is adapted to be retained by tightening of the nut at the rear end portion of the stud, said sleeve having substantially diametrically opposite sides pinched to the stud to securely engage the ridges on the stud and hold the sleeve against endwise motion away from the plate.

5. In an electric switch: an insulative terminal plate; a terminal stud having an enlarged head the front face of the terminal plate and a threaded stem projecting from, the rear face of the terminal plate and adapted to have a nut threaded thereon to secure a conductor to the terminal stud, the medial portion of said stud passing through a closely fitted aperture in the plate and having a plurality of longitudinal grooves which define ridge-like teeth adapted to ooperate with the material of the plate to preclude rotation of the stud in the plate; and means to preclude chewing of the plate bythe teeth of the stud and turning of the stud in the plate in consequence to tightening of a nut on the stud, said means comprising an annular conical member having its outwardly flared rim in engagement with the rear face of the plate and adapted to compact the material of the plate radially inwardly into said longitudinal grooves in the medial portion of the stud upon forward movement of the member, and a shoulder at the rear of said member adapted to receive the forward thrust of a nut as the same is tightened upon the stud.

EDWARD N. JACOBI.

REFERENCES CITED The following references are of record in the file of, this patent:

UNITED STATES PATENTS Number Name Date 1,660,560 Jacobi Feb. 28, 1928 1,894,327 Schellenger Jan. 17, 1933 1,995,420 Fisher Mar. 26, 1935 2,431,951 Mauerer Dec. 2, 1947 FOREIGN PATENTS Number Country Date 160,306 Germany Mar. 2, 1905 284,897 England Feb. 9, 1928 571,930 England Sept. 14, 1945

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