US2946036A - Electric switch with terminal plate and wire grip therefor - Google Patents

Description

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B-vwrw, www ma@ T. R. Bt-:TTENcoUR-r AND WIRE GRIP THEREFOR Filed June 22, 1956 ELECTRIC SWITCH WITH TERMINAL PLATE July 19, 1960 50 26 H W ,g Z7 r-r IL `\I'Ul l i T l l1 United safes Patent o s claims. (creas-L95) s This invention relates to terminal plates and wire'grips particularly intended for use in connection with electric switches. lt has for an object to'provide a gripping engagement with the wire whichtavoids any necessity for the use of terminal screws, and it also provides a terminal vplate particularly adapted for cooperation with the grip and which may carry selectively either a rivet for securfing a switch arm or la terminal button. A particular object of the grip constructionis to provide for the entire v'gripping action to be produoedby a spring arm which is rigidly anchored in the insulating casing.

' .A further object of the invention is to provide a construction by which the wire may be readily released from the grip when desired.

vFor a more complete understanding of this invention reference may be had to the accompanying drawing in which- Figure l is a side elevation of a switch embodying the invention; t

Figure 2 is a detail sectional view'onthe line 2.2 of Figure 1;

Figure 3 is abottom elevation of the switch;

Figure 4 is an exploded perspective view showing the terminal grip and plate, the plate being shown as having .riveted theretoa switch arm;

Figure 5 is a section on a larger scale on line 6- 6 rof Figure 1 butshowing the switch as lirst assembled and with thegrip unclamped; t

Figure 6 isa view similar to Figure 5 but showing Vthe grip secured rigidly in position and with a terminal Wire in gripped position; Figure7 is a sectional View on the line 7-7 of Figure l, on a larger scale, showing the wire released from gripping engagement by the use ofa second wire or tool;

Figure 8 is a sectional view on line 8-8 of Figures 1 and6; EL"

Figure `9,-is a sectional view` on line9-9 of Figure 7; am

Figure 10 is an enlarged perspective View of one of the terminal plates.

Referring to the drawings, 1 indicates a casing which houses the switch mechanism, the terminal plates and the necessary grips for the terminal wires. The walls, bottom and inner partitions of the casing 1 may conveniently be a single piece of molded insulating material, the top member being preferably but not necessarily a metal plate.

Referring to Figure 4, each terminal wire grip comprises a strip of spring metal having a pair of angularly related legs 2 and 4. From the leg 4 there extends a reversely curved porti-on 5, constituting a spring arm which extends diagonally toward the free end of the leg 2 and'then is bent backward as at `6 to form an end portion 7 extending toward the leg 4. The legs 2 and 4 are initially formed with an angle between them greater than 90 eg., 100 more or less, as shown best in Figure 5.

The casing 1 contains two similar rectangular chambers 10 and 10 for the grips, formed by Walls and partitions of the casing 1. Two opposed walls of the chamber 10 area partition 11 and a casing w'all 12. The Walls of the chamber are integral with the bottom 13 of the casing which forms the base of the chamber. The walls 11 Yand l 12. are provided with oppositely disposed guideways'lS and 16. The `guidewaylrreceives lateral extensions v17 and 18 of the leg 4 of the grip.V When the switch is being assembled, the grip is inserted into the chamber l0 Ythrough the open top thereof and is pushed into position as hereinafter described, the lateral extensions 17 and 18 sliding in the 'guideway 15 and the leg 4 of the grip bearing against thepartition wall 11. The leg 2 extends toward the guideway 16 and is engaged at the end of its upper face by a central rtab 20 struck up from a terminal plate 21 which is slidable in the guidewayl. The plate 21 has an embossment 22 below the tab 20 with a central groove24 therein to receive arterminal wire as will later appearl p The embossment 22 is of suicient height to keep the portion indented to form the groove 24 vfrom projecting beyond the plane of the rear face of the terminal plate 21. The plane portionsV of the'rear face of the plate thus bear directlyagainst the wall 12.

`Above the .terminal plate 21,A mounted to slidel in the guideway 16, is a flat piece of insulation 25. This insulation 25 extends above the level of the top of the chamber when the terminal grip is in normal unstressed condition as indicated in Figure 5. .When pressed downward to the position shown in Figure 6, it pushes the terminal plate 21 to its seated positionvat the bottom of the guidewayrl.

The location of the tabr20 is such that when the plate 21 i moves down to its seated position, the tab llexes the leg 2 to an approximately horizontal position, thus anchoring theleg 2 rigidly in position and causing the leg 4 to press strongly against the partition wall 11. If the length of the leg 2 is exactly equal to the distance between the partition wall 11 and the front face of the terminal plate V21, there will be a slight clearance between the end of the leg 2 and the face of the plate 21 when the parts are assembled unstressed as in Figure 5. In such case, the grip can Vbe dropped into the chamber through the open top thereof,'together with a terminal plate 21, and screws 26 which extend through a metal top plate 27 into the casing walls may be employed to press the piece 25iand plate 21 down to the seated position, andthe leg 2 will then be rigidly anchored. However, on account of `slight unavoidable variations inthe inner dimensions of the molded casing 1, the grip may be made so that the leg 2 is long enough to touch the front face of. the terminal and 4 immovable under rigid tension so that operational flexing of the grip is confined to the extension 5.

The bottom 13 is provided with a perforation 30 through which the bared end 31 of the conductor wire may be thrust. The grip is made with a hole 32 at the bend 6, a short lip 35 being formed at the lower edge of the hole. The outer edge of this lip is nearer to the terminal plate 21 than the `diameter of the wire to be inserted. On insertion of such a wire, the extension 5 and the end portion 7 of the grip are forced toward the left (Figure 6) by the Wire and when thus distorted press the wire against the face of the terminal plate within the groove 24, thus providing a firm electric contact therewith. Anyy attempt to withdraw the wire is resisted by the edge of the lip 35 grippingthe wire, which edge may. be slightly rounded so as not to cut too deeply into the wire if force is used in an attempt to withdraw the wire extension 5 to be engaged A'by :the extension 15 `ifthevvire l`3l 4'is`pulled with suicientforce. The bolster 36 then actsas `a stop to support the extension 5 'before'.the grip is distortedsutiiciently to be injured.

For each grip chamber, the`bottom13 is also provided with a second perforation 40 which is shown in 'Figures 3 and9 as oval in cross section and through which a wire or tool 41 may be thrust to engage the spring Aarm ata point on the bend oisetfrom the Ihole 32,*this'acting to wedge the spring arm 5 away fromthe wire3'1soas 'to release the wire therefrom. It will 4be noted 'that the leg 2 of the grip may act as a stop'when a wire 31 or a tool 41 is inserted into the chamber to `prevent the wire'or tool from being thrusttoo far into the casing. When a wire or `tool 41 is inserted to Vreelase the terminal wire 31, the

spring arm 5 is flexed so that the extremity of the end portion 7 approaches the leg 4. If thetool 41 is inserted at a skew angle, the arm 5 is additionally ilexedybutthe end portion 7 is made'long enough to engagethe arm 4 as a stop before the arm 5 can be flexed sufliciently'to damage the grip.

As shown in Figure 4 the terminal plate 21 has riveted thereto as at 45 a switch arm 46 carrying a terminal button 47 at its other end. This switch arm 46 extends into vthe chamber 10' and is arranged sothat its button 47 normally presses against a button 47' on a terminal plate 21 mounted in the chamber 10.

To open the switch, the arm 46 vis sprung to `separate the buttons 47 and 47' by any suitable means such `as a cam 52 carried by a toggle lever 50 which is fulcrumed at 51. The cam 52 moves from a-portion 53'to a portion 54 of the arm 46, these portions being mutually offset as indicated in Figures 2 and 4.

"I'he terminal plates 21 and 21 are each symmetrical with respect to the central wire-engaging portion, ise., the groove Z4. They are therefore interchangeable and can be used in switches containing more than two terminals.

From the foregoing description of an embodiment of this invention, it should be evident to those skilled in the art that various changes and modifications may be madetherein without departing from its spirit or scope.

I claim:

1. An electric switch lcomprising an insulating casing having a chamber, opposed walls and a base, Ya wire grip comprising a pair of angularly related legs one of which is rigidly pressed against one of `said walls, the other leg extending toward the opposite wall and being rigidly anchored imposition, and Va spring portion extending diagonally from said one legr toward the other leg and opposite wall and having an end portion bent back toward said one leg, and a terminal plate slidable against said the end of said `other leg and springing said other leg to Va bowed shape, said casing "having a hole through said bottom for insertion therethrough of a terminal wire between said spring portion and terminal plate to be gripped therebetween and means pressing said terminal plate downwardly to distort said other leg from its unstressed shape and to clamp said grip and plate in seated position againstthe Vbase ofsaid chamber.

2. In combination, a casing 'having .a .chamber provided with wallsand verticalpguideways at opposite walls thereof, a .wireggp comprisingta spring member .having a pair 'of anglaly related legs, .one .ofsid ulegs-being in one of said guideways and against one of said walls, the other of said legsextendingracross said .chamber toward the other of said walls, said iirstrnentioned leg having an extension projecting diagonally toward the free end of the other leg, said extension having an end portion bent back toward .said rst mentioned leg, said chamber 'having aba'se providedY with aholetherethroughadjacent to said other guideway through which a wire may be extended intogripping contact with said extension adjacent .tothe bend thereof, said "base having a raised bolster adjacent to said `extension to limit downward flexing thereof, 5a terminal plate slidably engaged in said other guideway, said plate having a projecting element overlying and engaging .the end of said other leg, Aan insulating member slidable in said other guideway and engaging with said plate, and means pressing said insulator and plate along said other guideway toseat said plate on saidbase, said overlying portion forcing the'legs ofsaid lgrip into a rigidly `fixed position, the bend of said `extension being normally closer to `said plate than the diameter of the 'wire for'engagement therewith.

3. The `combination as in claim 2, the bent-back :end portion of .said extension being constructed ,to approach said one'leg when said extension is flexed by Aa tool and .to engage said one leg as a stop before said extension can be 'excessively flexed by said tool.

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