US2470613A - Electric cam snap switch - Google Patents

Description

May 17, 1949. A. c. GAYNoR 2,470,613

ELECTRIC CAM SNAP SWITCH Filed April 18, 1945 2 Sheets-Sheet l l f7 .e @ik f7 ,am 7143- if NVENTOR BWM Md `d ATTORNEYS May 17, 1949. A. c. GAYNOR 2,470,613

ELECTRIC CAM SNAP SWITCH Filed April 18, 1945 2 sheet's-sheet 2 |NvENToR xxmwmgmx' )5 AM77/ur (f G'aymgff 25 24 27 2625292322 V20/Z www ZZA@ ATTORNEYS Patented May 17, 1.949

UNITED ,STATES PATENT OFFICE L'TR-IC SWTGII Joseph F. Gaynor, Milford, Conn. ppl-cth I8, 1945, S'/l N0. 589,026

11 Claims. 1

This invention relates to electric switches', `and more particularly to switches -o'f th'e type fknown vas `slow-breaking, wherein the contacts are not abruptly separated or snapped apart.

In everyday usage, lever-opera-ted Vswitches Ifor household appliances, drop and extension cords 'and the like are almost universally made with snap-operating contacts, the thought being that such switches may nd application in inductive circuits which, particularly in connection with direct current, are commonly know-n to produce troublesome arcing. While these snap-acting switches have in the past proved to begenerally satisfactory, their mechanisms were limited as to useful life, and `current capacity for 4a ygiven size.

In the past, in a large majority of cases, Asnap switches were employed in connection with alternating current circuits of the type which presented no problem of excessive rarcing, and therefore the abrupt or snap separation of 'the contacts was unnecessary, and indeed 'undesirable in that it tended to create a large or elongate arc. However, the feel of the snap movement of the levers rof such switches, and the sound of the snap were desirable characteristics which fou-nd public acceptance, and therefore widespread usage.

According tothe present invention a lever-type switch mechanism is provided, suitable for use with wiring devices, appliances and the like, which retains the snap or detent action of the lever, but has a long lived extremely simple and economically prod-ucible, slow-acting conta-ct mechanism advantageous for the great -majority of alternating current uses wherein substantial Aarcing does not occur. When the slow-opening contacts of the present switch fare separated,` the arc produced is Very small, not elongate `as in the case where abrupt sepa-ration of contacts `is effected by snap-acting mechanisms. l

4I have found that under ordinary conditions, when the switch `of the present invention is lemployed in 'an alternating current tcircuit, the arc at the contacts ybecomes extinguished .before the separation of the latter reaches approximately .005, due to the voltage passing through zero during some part of that movement.

The arc is extremely l"small, never being greater than .005, as `'compared with the elongate or drawn-outgarcs which may occur when the contacts yare abruptly separated and moved apart by snap-action. p l

I In the specific illustrated embodiment of the invention, 4the contact structure includes a specially-shaped, resilient, biased Vmetal contact-carrying blade acted on at one side by a compression coil spring and at the other side 4by a crank -or lever jcor-nprising the switch operator. The parts are -thus =ew in number, and may be of small dimension yet of large current capacity. Due to the simplicity yof the contact and operating mechanisms, and the action of the same,- the switch is trouble-free in operation, and has a long useful life.

The shape of the resilient blade or arm, and arrangement of the crank or lever operator is such that the latter when moved has imparted to it a snap action, especially pronounced when closing the contacts, and the re-engagement o'f the latter with each other is accompanied by a certain amount of impact, which functions 'to -dislodge'any dirt particles from between the contacts, and insures a positive electrical juncture.

lThere is thus achieved a slow-break switch of simple and economical construction which has desirable electrical characteristics well adapted -for `alternating current circuits, and which li'as a snap-acting lever operator convenient lin use.

A novel organization is provided in connection with the operating lever of the switch vwhereby the llatter maybe mounted in an extremely simple and economical manner for pivotal mbt/'ement withinthe switch casing. The mounting is such that the casing may Abe molded Ato the desired finished form without the necessity' of additional operations such as drilling and the like. Instead, the molding equipment for the casing may be' of the usual construction providing recesses 'and apertures in the molded part which do not Vprevent the latter lfrom being readily Withdrawn from the mold.

In accomplishing this, the operating lever f 'the switch .is provided with bearing plates a't each side,` in which the lever is pivoted, andthe casing provided with recesses which receive and l'nest the bearing plates, :positioning and .preventing the `latter from turning. The assembly o'f the operating 4lever to Athe casing is thus a matter'aof merely pressing into l place the lever and bearing 3 plates. In addition, the plates are provided with lugs which act as stops for limiting the movement oi the opera-ting lever.

Other features and advantages will hereinafter appear.

In the accompanying drawings:

Figure 1 is longitudinal section taken through the center of the switch of this invention, showing the parts in open-circuit position.

Fig. 2 is an underside or inside plan view of the upper half of the switch of Fig. 1.

Fig. 3 is a plan view of the lower half of the switch of Fig. 1.

Fig. 4 is a longitudinal section similar to Fig. 1 but showing the parts in closed-circuit position.

Fig. 5 is an exploded perspective view of the operating lever assembly, bottom side up, and

Fig. 6 is a longitudinal section similar to Fig. 1, but showing the contacts about to separate.

Referring to Fig. 1, the switch of the present invention comprises a two-part casing Ill having separable recessed halves or shells II and I2 which may be formed of the usual molded insulating material. The casing III, in addition to housing the switch elements, functions as a base on which the various elements are mounted for cooperation with each other. The switch shown is of the type used in connection with electric cords or lines, or used at the end of a pendant drop cord, and therefore the casing I at its ends is provided with channels I3 and I4 through which the electric wires may pass.

The casing halves II and I2 may be secured together in any suitable manner, that shown comprising screws I extending through apertures in the casing half I2 and threading into metal inserts I6 which are molded into the upper casing half II.

In the specic embodiment of the invention illustrated herein the upper casing half I I of the switch is adapted to carry an operating lever I1, together with associated bearing and force-transmitting instrumentalities, and the lower casing half I2 adapted to carry the switching mechanism which is responsive to the movements of the lever I1.

According to the invention, a novel simplified switching and operating mechanism is provided in the casing III whereby a comparatively slow break or separation of the switch contacts is elected by operation of the manually engageable lever I1, the make or re-engagement of the conta-cts being much faster than the break, and having a speed wherein there is a degree of impact for causing positive re-establishment of the connection. The mechanism is such that, with the stated contact action, a definite desirable detent and snap action of the lever is produced enabling a user to determine by touch and hearing as well as by sight the functioning of the switch.

Considering again Fig. 1, the switching mechanism carried by the casing half I2 comprises a stationary contact in the form of a resilient metal strip or arm I8 having at one end a contact disk I9, the other end of the arm being secured to a metal insert molded in the casing half I2. The insert 2B is of tubular structure, and is internally threaded to carry a binding screw ZI by means of which electrical connection is made to the arm I8.

For cooperation with the stationary contact disk I9 a movable contact disk 22 is provided, secured to the end of an elongate resilient metal strip or arm 23, the other end of which is fastened to a metal insert 24 molded in the casing half I2.

Like the linsert zu, the insert 24 is tubular and 75 4 internally threaded to receive a binding screw 25 by means of which electrical connection is effected between a wire conductor and the arm 23.

The resilient arm 23 is biased so that it tends to continually yieldably hold the contact disk 22 carried thereby against the stationary contact disk le. In addition, according to the present invention, a spiral coil spring 25 of the compression type is provided for engagement with the underside of the arm 23 and with the casing half I2 to augment the pressure of the contact disks I9 and 22, the total pressure being suiiicient to cause a slight yielding of the stationary arm I8 when the parts are in the position of Fig. 4. As shown in Figs. 1 and 3, the casing half I2 is recessed to provide space and clearance for the switching mechanism comprising the arms I8 and 23, and the coil spring 2B.

For the purpose of operating the switching mechanism of the casing half I2 whereby a slow separation of the contact disks I9 and 22 is efected, the resilient switch arm 23 is formed intermediate its ends with a plurality of reverse bends so that the arm has the shape of a flattened lvl. The center or depressed portion 21 of the M is engaged by the coil spring 26, as shown in Figs. 1 and 4, and the right-hand portion functions as a projection or protuberance, providing a sloping camming surface 28 and a tip portion 29.

Cooperating with the sloping portion 28 and tip 29 of the arm 23 and carried by the lever I1 is a force-transmitting means comprising a pair of rollers Eli mounted on a shaft or pin 3| which latter is carried by a T-shaped plate 32 nesting in a recess 33 of the lever I1. As shown in Figs. 2 and 5, the rollers 3Q are disposed on each side of the supporting plate 32, and the latter has an aperture 34 aligning with apertures 35 in the central portion of the lever I1 so that a pin 36 may be extended through all apertures to secure the plate and lever together.

For the purpose of conveniently and economically mounting the lever I1 and associated forcetransmitting instrumentalities in the upper casing half II, a pair of T-shaped bearing plates 31 is provided, having apertures 3B through which the pin 36 may also extend. The lever I1 is therefore pivotally connected to the bearing plates 31.

Referring to Figs. 1 and 2, the upper casing half I I is provided with an elongate central aperture 39 to accommodate the operating lever I1, and in the opposite walls of the aperture 39 recesses 4B are provided, adapted to receive and nest the bearing plates 31. rEhe recesses 4I] do not extend to the outer wall .fil of the casing, but terminate in walls d2, as shown by the dotted lines in Figs. 1 and 4. By this construction the lever I1, bearing plates 31 and roller supporting plate B2 may be secured together by the pin 3S, and the entire assemblage pressed into place in the casing half il, where they will be held by the rictional engagement between the plates 31 and the casing.

When the lever assembly is thus pivotally supported in the casing half II, the rollers 3G will be in position to engage and operate the resilient switch arm 23, as shown in Figs. 1 and 4, this engagement also preventing the lever and mounting assembly from sliding out of the recesses in the casing half.

Preferably the bearing plates 31 have portions 31a which extend alongside the rollers 3l] and past the ends oi the pin 3l on which the rollers are carried. The extensions 31a therefore limit endwise movement of the 'pin 3l, and insure the latter properly carrying the rollers 3B at all times. For the purpose of limiting the arc of movement of the lever H the bearing plates 3l' are pro vided with lugs 43 extended inward laterally for engagement with the undersurface 44 of the lever. Referring to Fig. 1 Vthe lever I1 is shown engaging at its undersurface a lug 43 which latter therefore determines the extreme counterclockwise limit of movement of the lever. In Fig. 4 the clockwise limit of movement of the lever il is shown, this limit being determined by the other lug 43, of the opposite bearing plate 31.

The voperation of theswitch is as follows: Referring to Fig. 4, the switch is shown in closedcrcuit position, the contact disks I9 and 22 engaging each other under pressure from the spring 26 and also fromI the bias given the resilient arm 23. The rollers 3@ carried by the operating lever il may or may not rest against the sloping surface 28 of the resilient arm 23; if they do rest against the surface 28 there will .be comparatively little pressure exerted, so that a maximum pressure exists between the contact disks. When operating pressure is rst applied to the left-hand end of lever Il', the lever will have moved an extent as shown, moving the arm 23 slightly, and the latter will be followed by the contact la for a short distance without separation of the contacts. This action is possible due to the resiliency of the arm I8.

When the lever H is moved further, to the position shown in Fig. 1, the rollers 3Q will cammingly operate and depress the arm 23 by traversing the inclined surface 28, thereby comparatively slowly separating the disks i9 and 22, the nal position of the rollers being somewhat over the tip portion 29 of the arm. For this final position the pin 3| carrying the rollers 3U will have passed a line drawn through the pivot pin 3 and through the point of engagement between the rollers 3D and the tip portion 29, so that a detent is thereby provided for the lever. The open-circuiting movement of the lever il causes a slow separation of the contact disks I9 and 22, the speed of break being proportional to the speed of movement of the lever, and being comparatively slow due `to the camming effect obtained. As shown in Fig. l, the f spring 2S is compressed an extent, and the arm 23 depressed by the movement of the lever ll and rollers 3U. Due to the slow separation of the contacts, the are occurring between the latter will be of small size, not over .005 long, and will be extinguished before a greater separation of the contacts occurs, due to the voltage `passing through zero immediately after the ini-tial break or during a subsequent voltage reversal. The small arc causes less burning of the contacts than would occur with a large arc such as results from a quick separation of contacts.

'I'he detent action obtained when -the pin 3l passes the center line common to the pivot 36 and the point of engagement between the rollers 30 and the arm 23 also tends to complete, with `Aa slight click, theV movement of the lever il to its final, limited position, because of the pressure on the rollers by` the arm. Thus a definite feel is imparted to a user, indicating that the switch is in full open-circuit position.

When the lever l1 is moved against the detent for the purpose of closing the switch circuit, the pressure of the spring 2B 'and' resilient arm 23 on the rllers will 'ca's'e ya snap a'ctioh 4of the lever to been". itf a "irai amnent di fte lever.. it will b duklif'r iifrieii 't6 the einem closed-circuit positin shtv'i Fig. 4 with a distinct snap. y,

As a result of 'thisjaw willstrike the disk' l9` ne certain ambunt of mpact, dislodgihg vany and breaking down l'llm which might been the coritacts, s`o` l'as to insure positive electrical ciiifiectioi'i.

There is thus provided the invention a switch having a sl'vv'r operi rig and fast closing contact mechanism wl'iili suitable and advantageous where hon-inductive, alternating current circuits are t be cofritblled, and having a distinct det'ent arid snap Aaction of the operating lever.

variations nd inodintiqns may be made within the scope of invention and portions of the improvements mai7 be used Without others.

, l. An electric switch oomprising a basel a stationary cntactmountel the base; a movable contact forvengagement with the stationfa'lfS7 contact; a resilientarm carrying the movable contact, said arm at one end being anchored to the base and being biased to "ielda'bly hold the contacts together; resilient means engaging the base and resilientarm, for lpieseing against the latter in a directionlto also holdnthe contacts tgether; an operating lever pivotally mounted on the base movablebetween on and off positions; and linkage means for flexing the arm and opposing said resilient I 'ne'ar'rs to separate the said contacts when the lever is-ino'ved from on to off position, including detent means 'for yieldably holding the lever 'in off position, said linkage means operating, kin response to force from the arm and resilient means, to snapvthe lever to on posi-tion so that Vcontacts may re-engage after the lever has rst been moved to overcome said detent means.

2. An electric switch comprising a base; a stationary contact mounted on the base; a movable contact for engagement with the stationary contact; a resilient army carryingl the movable contact, said arm at one endbeing anchored to the base and being biased to yieldably hold the contacts together; a Acoilspring engaging the bas-e and resilient arm, andv pressing against the latterin a direction to also hold4 the contacts together; anv operating lever lpivotally mounted on the base, movable between on tooi positions; and linkage means for flexing the arm and compressing the coil spring to separate the said contacts when the lever is moved from on to orf position, including detent means foryieldably holding the lever in off position, said linkage means operating, in response to force from the arm and spring, to snap the lever to on position so that the contacts may re-engage after the lever has rst been moved to overcome said detent means. l

3. An electric switch comprising a base; a pair of metal arms anchored each at one end to the base, said arms extending in line with and toward each other, the adjacent ends overlapping for making electrical Contact, and one of said arms being resilient and biased for engagement with the other arm and the other arm being limitedly yieldable in the direction of movement of said rst arm during movement thereof to engaged position; an operating lever extending alongside the arms, said lever being pivotally mounted at its center on tliebase, and having fa projection e'i'ite'i'diiig from atli'e pivet toward the resilient arm; and a projection on the resilient arm for camming reversible driving engagement with the projection of the lever` whereby opposite movements of the latter causes the said arm to flex and respectively engage and disengage the other arm, closing and opening the circuit of the switch, the said projections being so located that the lever may be moved, when open-circuiting the switch, to cause the centers of the projections to pass each other and prevent automatic return of the lever and reclosing of the switch.

4. An electric switch comprising a base; a pair of metal arms, anchored each at one end to the base, said arms extending in line with and toward each other, the adjacent `ends overlapping for making electrical contact, and one of said arms being resilient and biased for engagement with the other arm; a coil spring engaging the base and resili-ent arm for urging the end of the latter in engagement with the other arm; an operating lever extending alongside the arms, said lever being pivotally mounted at its center on the base, and having a projection extending from the pivot toward the resilient arm; and a projection on the resilient arm for camming reversible driving engagement with the projection of the lever Whereby opposite movements of the latter causes the said arm and the coil spring to flex so that the arm respectively engages and disengages the other arm, closing and opening the circuit of the switch.

5. An electric switch comprising a base; a pair of metal arms, anchored each at one end to the base, the other ends of the arms overlapping and touching for making electrical contact, one of said arms being formed with an inclined surface, said arm being resilient and biased for engagement with the other arm; a compression coil spring interposed between the base and the resilient arm, bearing against the latter adjacent the inclined surface thereof for yieldably holding the arms in engagement; and an operating lever pivotally mounted on the base, having a portion engaging the inclined surface of the resilient arm opposite the coil spring for camming operation of the latter whereby opposite movements of the lever and arm-engaging portion thereof cause the said arm and spring to ex so that the arm respectively engages and dis- -engages the other arm, the inclined spring surface and engaging portion of the lever being shaped to provide a detent for yieldably holding the lever in open-circuit position.

6. An electric switch comprising a casing having two separable halves; a pair of metal arms, anchored each at one end to one half of the casing, the other ends of the arms overlapping; contact buttons carried by the overlapping ends of the arms, for making electrical contact between the latter, one of said arms being resilient and biased to yieldably hold the buttons in engagement; a sloping projection on the resilient arm; and an operating lever pivotally mounted on the other casing half and projecting through the same, said lever having a portion engaging the projection of the resilient arm for camming operation of the latter whereby opposite movements of the lever and arm-engaging portion thereof cause the said arm to flex and respectively engage and disengage the contacts.

7. An electric switch comprising a casing having two separable halves; a contact iixedly mounted in one half of the casing; a metal arm mounted in the said casing half, the arm being movable and adapted to engage and disengage the said Contact, and being yieldably maintained in engagement with the latter; a sloping projection on the arm; and an operating lever pivotally mounted on the other casing half and projecting through same, said lever having a portion engaging the projection of the arm for camming operation oi the latter whereby opposite movements of the lever and arm-engaging portion thereof cause said arm to respectively engage and disengage the contact.

8. In an electric switch, a support having an opening therethrough; an operating lever extending in said opening, having pivots on each side; a pair of apertured bearing plates carrying said pivots in the apertures thereof, the Walls of the opening of the support being recessed to slidably receive and nest the bearing plates and prevent the latter from turning; and lugs on the bearing plates positioned in the path of move-v ment of said lever for engagement by the lever whereby movement of the latter is confined between two limits.

9. in an electric switch, a support having an opening therethrough; an operating member extending into said opening; bearing plates on opposite sides of the operating member, pivotally cnnected to latter, the walls of the openg oi the support being recessed to slidably reeive and nest the bearing plates and prevent the eine from turning; means associated with the earing plates and operating member for preventing movement of the latter beyond either ci two limits; a roller Carried by the operating member, for transmitting force therefrom, said member having a sha-it on which the roller is rotatable, the said bearing plates extending on opposite sides of the roller and past the ends of the sh it for limiting endwise movement of the latter.

iii. [en electric switch comprising a casing having two separabie halves, one oi said halves having an opening therethrough; an operating lever extending through the opening of the said one casing haii; bearing plates on opposite sides of the operating lever pivotally connected to the latter, the walls of the opening of the said casing being recessed to slidably receive and nest the bearing plates and prevent the same from earning; means associated with the bearing plates and operating lever for preventing movement of the latter beyond either of two limits; and contact means carried by the other casing half and operable by the lever whereby when the latter is at one or the other of said limits the contact means are engaged or disengaged respectively.

il. An electric switch comprising a casing having two separable halves, one of said halves having an opening therethrough; a contact xedly mounted in the other half oi the casing; a metal arm mounted in the contact-carrying half oi the casing, the arm being movable and adapted to engage and disengage the said contact, and being yieldably maintained in engagement with the latter; a sloping projection on the arm; an operating member extending into the opening of the said one casing half for pivotal movement therein, said member having a portion engaging the projection of the arm for camming operation of the latter whereby opposite movements of the lever and arm-engaging portion thereof cause the said arm to respectively engage and disengage the contact; bearing plates on opposite sides of the operating member, pivotally connected to the latter, the walls of the opening of 9 the said one casing half being recessed to slidably receive and nest the bearing plates and prevent the same from turning; and means associated with the bearing plates and operating member for preventing movement of the latter beyond either of two limits at which the arm respectively engages and disengages the contact.

ARTHUR C. GAYNOR.

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

UNITED STATES PATENTS Number Name Date 692,825 Carliss Feb. 11, 1902 1,424,402 Hartman Aug. 1, 1922 Number Number Name Date Tregoning Aug. 29, 1933 Tamsitt Dec. 5, 1933 Gaynor July 10, 1934 Schellenger Jan. 26, 1937 Brown Sept. 17, 1940 Benander Jan. 6, 1942 Dettar Jan. 20, 1942 FOREIGN PATENTS Country Date Great Britain July 31, 1924 Great Britain Oct. 22, 1928 Great Britain Oct. 3, 1939 France Jan. 22, 1929

Images