US2755353A

US2755353A - Overcenter snap switch

Info

Publication number: US2755353A
Application number: US372862A
Authority: US
Inventors: Robert W Bachi
Original assignee: SORENG PRODUCTS CORP
Current assignee: SORENG PRODUCTS Corp
Priority date: 1953-08-07
Filing date: 1953-08-07
Publication date: 1956-07-17
Anticipated expiration: 1973-07-17

Description

July 17, 1956 R. w. BACHI OVERCENTER SNAP SWITCH 3 Sheets-Sheet 1 Filed Aug. 7, 1953 2w m/ 3 u 7 v B 5 0 4 Z 3 3 W x Ill 6 I 2.0 5 5 f a 3 a. g

a 7( ea 5 :ikll v J Bllv l July 17, 1956 R. w. BACHI OVERCENTER SNAP SWITCH 3 Sheets-Sheet 2 Filed Aug. 7, 1953 3440M 1201792"? H Zia/21 July 17, 1956 R. w. BACHI 2,755,353

OVERCENTER SNAP SWITCH Filed Aug. '7, 1953 s Sheets-Sheet s s /////7/////A if United States Patent OVERCENTER SNAPSWITCH Robert W. Bachi, Itasca, IlL, assignor to Soreiig Products Corporation, Schiller Park, 111., a corporation of Delaware "Application-August 7, 1953,. Serial No. 372,862

. 11 Claims. -(l. mil-+67) This invention relates to snap switches and has more particular reference to snap switches of the overcenter or toggle action type.

Switches of this type generally comprise a flexible contact blade having a fixed end and a movable end portion cooperable with a stationary contact, a tripping --arrn-mounted flatwise alongside the contact blade and capable of fiexure to one side or the other of the plane *of the contact' blade, and an overcenter compression spring connected between the tripping arm and the blade to effect snap actuation of the movable end portion of the blade in one direction with respect to its stationary contact in consequence of motion of the arm in the opposite direction past the plane of the blade.

The snap switch of this invention is disclosed in part,

.butnot claimed, inthe copending application of Robert '-W.- Bachi, SerialNo. 347,437yfiled April 8, 1953.

One of the objects of 'thisin'vention resides in the provision of a-relatively small overcenter snap switch of the-character described featuring arigid trip -link or -lever having an unusually longstrokefor switches of this type, and employing a stronger overcenter compression spring'than was hitherto used to efiect snapping of -the-free end-portion of the contact blade between the two positions of the switch.

Theadvantage of providing a relatively strong overcenter spring and a rigid trip link'having a relatively long operating stroke is that not only can'exceptionally good contact pressure he maintained between the contact bladeand-its cooperating stationary contact even though the switch mechanism maybe subjected to shocks or vibration; but the initial engagement of the contact ;blade with its cooperating statonary contact during 'tripping of theswitch will be eifected under exceptionally good contact-pressure to-preclude any arcing duringsuch initial engagement ofthe'switch contacts.

A further advantage is that ininstances where the free end portion of the contact blade operates between spaced stationary contactstobreak one circuit and make another circuit,-when the switch is tripped, the stationary contactsmay be spaced farther apart than was possible heretofore in switches of this type, and the spacing of these contacts is far less critical than was the case when the movable;end of'thecontact blade travelled but a short distance from one switch position-to the other. withthisuarrangement, also, it will be appreciated that vthe increasedinitial contact-pressure as well as final contact pressure between the movable end: portion of: the contact blade .and. thestationary contact or. contacts substantially eliminates bounce which. hashitherto presented a problern whenever overcenter-snap switches, of comparable size but of shorter throw were provided.

A related'object resides in the provision of an overcenter snap switch of the character describedwhich will not requireinspection to. make sure that close tolerances .are held'in the manufacture of the operating parts of the switch,;and which will. operate entirely. satisfactorily without such inspections.

I 2,755,353 :litatented July 17; 1:956

Still another object resides in the provision ='of-n'ovel spring seats on the trip link and contactblade which assure unusual stability for the relatively'strong overcen-ter spring by eliminating any tendency for the spring-to "buckle during tripping of the switch.

A- further object of the invention resides in theprovision of a unique housing for the snap switch. I

With the above'and' other objects in view,--Whii:h=-Will appear as the description proceeds, this inventionaesides inthe novel construction, combinationand'arrangement of parts substantially as hereinafterdescribed,*and*rnore particularly defined by theappended claims, it"being understood that such changes in the precise-embodiment :iofi'the herein disclosed invention may be made-as'come *within the scope of the claims.

The accompanying drawings illustratetwo complete examples of the physical embodiments of 'the invention constructed in accordance with 'the bestmodes so 'far devisedfor' the practical application ofthe-principles thereof, and in which:

"Figure l is a perspective view of the' -housing for'the switch of this invention;

"Figure 2 is a longitudinal sectional view through the housing to illustrate its construction and 'showing'the snap switch of this invention in place therein;

" Figure 3 is a cross.sectional'viewtaken throu'gHFigure'2'along the plane of'the line'3-"3;

Figure 4 is a separated perspective view of the two housing sections showing "the switchmechanism'mou'nted on'one of the housing sections; V

Figure 5 is a separated'perspective view of'therigid operating'link and thecontactblide of the-switch-of this invention;

Fignre 6 is adiagrammatifideta'il view showing 'the type-ofspring seats which are employed to'rnost advantageouslyconnect the overcenter spring between-the t'rip 'link" andcontact blade;

--Figure 7 is alongitudinal sectional view on"the order of Figure 2 'showinga modified embodiment of'the'inventionyand Figure 8 =is'a' cross sectional view through'l igure"7 taken along the plane of the line 88.

Referring-n0w moreparticula'rly to the accompanying' drawings, in' which like reference characters indicate like-parts throughout the several viewsfthe 'numer'al 5 generally designates the housing and 6 the overce'nter snap-switchpf this invention. The housing comprises upper and'lower' housing sections 7- and '8, respectively, of insulative material, and the switch6 is-"mounted upon the lower housing section'8 in a'manner -to "be described hereinafter.

'The'lower housing section 3 comprises 'an elongated switch base of= generally rectangular outline, having upright-side'and end edges 9, and a substantially flat un'derside-10. The top of the base has a cavity" 11 therein"defininga highlevel support 12 adjacent to one end=of the base, -a low'level supportlli adjacent tothe other end ofrthe base, and rails'or shoulders'15 along'the longitudinal sides of *the'base having their upwardlyfacing surfaces lying in a common plane a slightdistance' above .that of: the high level support-12.

-The upper'housing section 7 'providesa cover which -Medially-of their ends the longitudinal-;sidewalls lof thecover are-provided with relatively large rectangular notches-2.0 therein, opening to the underside of the'fcover, and having a depth substantially corresponding to the maximum thickness of the base. These notches are normally closed by mating pads 21 projecting outwardly from the longitudinal edges of the base with their outer surfaces flush with those of the cover sides. Elongated shoulders 22 projecting downwardly from the under surface of the top wall along the longitudinal sides of the housing and having their surfaces flush with the bottoms of the notches in the cover sides abut the shoulders 15 on the base to hold the housing sections in proper positions relative to one another with the top of the base spaced from the top wall of the housing and the switch 6 accommodated in said space.

Aligning holes

24 and 25 in the cover and base extending vertically through the pads 21 and the bottoms of the notches in the cover provide for securement of the housing sections together as by means of the rivets 26 or other equivalent fastening means.

The top wall of the housing is provided with a boss 28 projecting upwardly from its center and having a bore 29 which communicates with the interior of the housing through a counterbore 30. The junction between the bore and counterbore defines an abrupt annular shoulder 31 facing the interior of the housing.

The boss slidingly accommodates an actuating member in the form of a control button 32. The control button has an enlarged cylindrical intermediate portion 33 slidable in the counterbore 20, a shank 34 projecting upwardly in the bore 29 to extend a distance beyond the upper end of the boss, and a reduced stem 35 projecting downwardly from the intermediate portion 33 into the interior of the switch housing to provide for actuation of the switch mechanism.

As shown in Figure 2, the switch may be provided with two

stationary contacts

36 and 37, the contact 36 being carried by the top wall of the housing and the contact 37 being carried by the base. It should be understood, however. that for many uses, only one stationary contact need be provided. The contact 37 is mounted on the low level support on the base, and the contact 36, of course, is mounted directly above the contact 37, in spaced relation thereto. Each of the stationary contacts is provided by the head of a rivet 38, and these rivets are employed to fix a pair of

terminals

39 and 40 to the upper and lower housing sections, respectively, in good electrical contact with the

stationary contacts

36 and 37.

Each of the terminals is bent to substantially right angle shape from flat strip metal stock to provide an upright leg and a horizontal leg integral with the upright leg. Referring to Figure 3 it will be noted that the upright leg 41 of the terminal 40 is received in a recess or groove 42 in one longitudinal edge of the switch base adjacent to the low level support 13, the groove or recess having a depth substantially equal to but not greater than the thickness of the leg 41 so that its outer surface will lie flatwise against the inner surface of the adjacent cover side wall and substantially flush with the edge of the base adjacent to the groove. The horizontal leg 43 of the terminal 40 projects inwardly over the low level support 13 and seats flatwise thereon, to be held securely on the low level support by the rivet 38 which passes through the low level support and provides the stationary contact 37.

The upright leg 44 of the terminal 39 extends along the opposite longitudinal edge of the base and may likewise be fiatwise received in a shallow recess or groove therein. In this case, however, the groove 45 has been shown provided in the side wall of the cover, and it also has a depth substantially corresponding to but preferably slightly less than the thickness of the upright leg 44 of the terminal 39 so that the outer surface of the leg 44 will lie substantially flush with the inner surface of the side wall of the cover and will fiatwise abut the adjacent edge of the base. Again referring to Figure 3 it will be noted that the upright legs of the terminals 39 4 l and 40 substantially embrace the longitudinal edges of the base 8, and this arrangement is desirable since it pro vides maximum electrical clearance between the downwardly projecting exposed ends of the terminals. While the downwardly projecting leg of the terminal for the lower stationary contact could just as well extend over the end edge of the base, it is desirable to locate it as shown for the reason that when so disposed the same switch base and snap switch thereon can be used for switch units having either one or two stationary contacts.

The horizontal leg 46 of the terminal 39 lies flat against the underside of the top wall 18 of the housing, and is securely fixed thereto by the upper rivet 38 which provides the stationary contact 36.

The switch mechanism 6 comprises a flat elongated contact blade 48, of resilient spring stock having one end fiatwise secured on the high support 12 by a rivet 49 passing therethrough, and having its free end portion extending between the

stationary contacts

36 and 37 for cooperation with one of them in either position of the switch. As shown best in Figure 5 the contact blade 48 has an elongated central cutout 50 therein, one edge 51 of which lies closely adjacent to the high level support and faces the free end of the blade. The other edge 52 of the cutout is at the free end portion of the blade and faces the fixed end thereof. A tongue 53 on the mid portion of the edge 52 and projecting inwardly there from toward the edge 51 provides one of the seats for the overcenter spring, and it will be noted that the opposite edges 54 of the tongue converge toward its extremity.

The outer end of the spring blade is capable of fiatwise ficxure downwardly into engagement with the stationary contact 37 (as seen in Figure 2) or upwardly away from the stationary contact 37 and into engagement with the stationary contact 36. Preferably a contact rivet 55 having heads exposed at both faces of the contact blade is fixed to its outer end portion for cooperation with the stationary contacts.

The opening 50 in the contact blade accommodates a trip link 57 which according to this invention comprises a rigid lever stamped from sheet metal stock. The inner end portion 58 of the lever is received in the opening 50 of the contact blade and is provided with a crease 59 into which the bearing edge 51 on the fixed end of the blade projects to fulcrum the lever for back and forth swinging motion through the opening in a path substantially normal to the plane of the blade and intersecting said plane. The outer end portion 60 of the lever comprises a substantially flat arm radial to the hinge or fulcrum axis of the lever, and is joined to the curved inner end portion 58 by means of a substantially flat inner arm 61 on the lever disposed at a relatively large obtuse angle with respect to its outer arm 60.

The rigid lever or trip link 57 has a lengthsubstantially shorter than that of the contact blade, and in fact shorter than the longitudinal dimension of the opening 50 in the blade, so that when it is seated on the knifeedged bearing 51 at the fixed end of the blade the extremity of the lever will travel in an are which is spaced a distance from the spring seat defined by the edge 52 of the opening and the tongue 53 which projects therefrom. The outer end of the lever is also provided with a square-cut shoulder 62 and a tongue 63 projecting outwardly therefrom and having converging sides 64 similar to those on the tongue 53 of the contact blade. The shoulder 62 and the tongue 63 also define a spring seat on the lever which is cooperable with the spring seat on the contact blade to retain the overcenter compression spring 66 connected between the outer end of the lever and the outer end portion of the contact blade.

The compression spring 66 may be an ordinary helically wound spring, but it has been found preferable to employ a barrel-shaped spring as shown best in Figure 2.

As thereinseen, the intermediate. convolutions of the .spring have substantially, greater diameter than those at the opposite ends .of the spring, and it is important to note that the end convolutions 67 are groundto provide .end surfaces on the spring which lie in planes normal to the axis of the spring. Moreover, these end convolutions have. a diameter such that they will snugly embrace the tapered sides of the

tongues

53 and 63 near their bases ...as seen in Figure6.

These wedge-like connections between the ends of the spring. and the

tapered tongues

53 and 63 provide exceptionally good rocking seats for the overcenter spring .and unusual stability to prevent buckling of the spring as might be the case if the tapered tongues were to fit .,loosely in the end convolutions of the spring.

.The barrel spring 66, of course, -will always be under substantial compression when confined between the spring .-seats on the trip link and contact blade, and this assures thatineither the upwardly or downwardly flexed condi- ...tion..of..the contact blade its contact will be held in engagement-with one or the other of the stationary con- .tacts withexceptionally good contact pressure therebetween.

I It willbe noted that with the barrel spring 66 properly connected between the outer end portions of the trip link and contact blade, the latter is placed in tension by .the spring while, the trip link is placed in compression. .lnother words, the barrel spring exerts a force upon the trip link tending to move the same endwise toward the fixed. end of the contact blade to thus assure that the .creased inner end of the trip link will remain properly seated or fulcrumed upon the bearing edge 51.

.Attention is also directed to the fact that the inner end, portion. 58 of the trip link has a width greater than .tjhatof. the opening 50 in the contact blade, and is pro- ,vided with relatively. narrow notches 69 in its opposite .side edges in line with the crease 59 vto receive the edge ,portionsof the contact blade which define the longitudinal Iedges. ,of the opening-50 therein. The purpose of this inte rlocking connection between the inner end portion of the trip link and the fixed end portion of the contact blade is to assure that the link willremain properly seated upon the bearing edge 51 during switch assembly operationsorduring. the applicationof any abnormal high im- {pact forces onto the link which would tend to unseat the .same.

,The fswitch. illustrated in Figure 2 is-further provided with a compression spring 71.having one end portion .received in an upwardly opening well 72 in the base i; of the housipgand its upper end bearing against the underside of. the arm 60. of the trip link closely adjacent to. the junction of its inner and outer armsto bias the trip link upwardly toward, the top wall of the housing. In order to assure against disengagement of the biasing spting71 from the underside of the lever a tongue 73 is struck downwardly from the arm 66 to engage in the convolutions at the upper end of the spring and thereby prevent shifting of the spring with respect .to the lever.

As seen in Figure 2 the biasing spring 7l'holds the trip link or lever 57 swung upwardly in one of the two positions of the snap switch mechanism, which position is defined by the. engagement of the outer arm 64) of the linkwith the adjacent. end of the stem 35 on the actuat- ,ing button 32. In this position of the parts the actuatingbutton32 is held by the spring '71 at. its upward limit .oftraveldefined by the engagement of the enlarged medial portion 33 on. the button withthe. downwardly facing j'shoulder 31 at the bottom of the counterbore in theboss28 in which the actuating button is slidably mounted.

Attention isdirected to the fact that in the position of theswitch illustrated.in Figure 2 the outer arm 6% of ,the triplink or lever. is. held spaced a substantial distancfrom. the plane. of the contact bladetd-by the combined forces of the spring 71 and the barrel spring 66. The

' hitherto possible.

overcenter spring 66 also exerts a substantial downward .force on the contact blade to hold the same flexed away from the arm 69 of the trip link and maintain the movable. contact 55 on the blade engaged with the stationary contact 37 with exceptionally good contact pressure therebetween.

It will also be noted that the lever must be. swung downwardly on its fulcrum through an arc of substantial length, by inward depression of the actuating button, before the arm60 of the trip link will reach a position coinciding with the plane of the contact blade and which position represents dead center ofthe toggle-connected link and. blade. Downwardswinging of the, trip link beyond the dead-center position, of course, effects tripping of the switch by the overcenter barrel spring 66Yto snap the contact end of the blade upwardly into engagement with the upper stationary contact 36 of theswitch.

This second position of the switchparts is indicated in construction lines in Figure 2, and willobtain as long as the actuating button 32 is held depressed. Upon release of the actuating button the biasing spring 71 returns the switch to the position shown inv full lines in Figure 2, and it will be thus appreciated that the biasing spring '71 has a force great enough to overcome that of the overcenter barrel spring 66. The trip link or lever 57, of course, will remain properly seated on its bearing edge or fulcrum 51 despite the application of downward force thereto by the actuating button, and despite the force exerted thereon bythe biasing spring. This results from the fact that for all normal operation of the switch, the crease S9 ,in the link is deep enough to prevent unseating of the link.

As stated previously, the limit of upward swinging motion of the trip link or lever 57 is defined by. theengagement of the outer arm 60 with the stern of the actuating button. Downward swinging motion of the triplink may be. limited to the stroke of the actuating button '32. or, in other words, the distance the shank portion of the buttonnormally projects from the top ofthe boss' 28 on the top of the switch housing. Alternatively. the downward limit of swinging motion of the lever canbe defined by the engagement of its outer arm 69 with a ledge 75 in the recess- 11 in the top of the switch base, directly beneath the actuating button.

- It will be seen that in swinging between its upper and lower limits, the-arm 6t? on the trip link or lever travels through an arc of relatively great length for small snap switches of thisv type, and this is one of the features of the switch of this invention. Since the lever. must swing relatively far before it reaches thedead-center position coinciding with the plane of the contact .blade, the stationary contacts may be located fartherapart than was in addition the overcenter barrel spring 66 can be relatively strong to effect engagement, both initial and final, between the movable contact and either stationary contact under greater pressure than has been possible in the past insmall overcenter snap switches of the type herein concerned.

This is an exceptionally valuable feature wherever the snap switch is. to be used in environments where it might be subjected to vibration or shocks, in that it eliminates substantially. all tendency of the contacts to bounce or to are either during their initial engagement or after their engagement under the full force of the overcenter spring. This assures long life of the contacts and of the spring mechanism generally in such installations as that shown and described in the copending application of Robert W. Bachi, Serial No. 347,437 filed 'April 8, 1953, wherein the switch forms part of a powerful electromagnetically operated latch mechanism of the type used on refrigerator doors.

The third terminal 77 of the switch is similar to the terminals 39 and 4d and has one leg 78 thereof flatwise overlying the high level support 12 in superimposed relation with the fixed end of the contactblade,-and-is secured to the base by the same rivet used to anchor the contact blade to the switch base. Its downwardly projecting leg 79 is received in a shallow groove or notch 80 in the adjacent end edge of the base so that the outer surface of the leg 79 will lie substantially fiush with or leven project slightly from the adjacent end edge of the ase.

Accordingly, the outer surfaces of all of the downwardly depending legs of the

terminals

39, 40 and 77 are disposed in the telescoping joint between the cover and the base and do not interfere with sliding of the cover over the base at the time the two housing sections are secured together. Moreover, since the depending legs of the terminals are held snugly engaged in shallow grooves in the housing by the telescoping engagement of the housing sections, any lateral forces exerted upon the terminals tending to bend the same will not be transmitted to the riveted connections between their inner ends and the switch base; and these rivets will remain tight at all times.

In the assembly of the switch device all of the switch parts are assembled on the base 8 of the switch housing. The trip link or lever 57 may then be held swung downwardly part way toward or near dead center position (not shown) by a tool projected laterally across the top of the base over one of the two pads 21 which project from its longitudinal sides. This is done to maintain the barrel-shaped overcenter compression spring 66 properly connected between the trip link or lever and the contact blade until such time as the cover is in position on the base completing the housing. While the trip link or lever is held thus depressed, the cover is slipped downwardly over the base while the actuating button 32 is held depressed, and with one of the notches 20 in the opposite longitudinal sides of the cover accommodating the tool by which the trip link or lever is held depressed. Before the cover reaches its final position fully enclos ing the base, the stem 35 on the actuating button will engage the outer arm 60 of the trip link or lever and the tool may be withdrawn from either notch in the cover, and the cover thereafter pushed down to its final position and riveted or otherwise secured to the base in the manner described.

It will be seen, therefore, that the interlocking connection between the cover and the base afforded by the notches 20 in the cover sides and the pads 21 on the sides of the base not only provides stability for the telescoped joint between the cover and the base, but these notches also provide access ports to enable the overcenter spring 66 to be held properly connected between the lever and contact blade by a tool accommodated in one of these notches during the application of the cover to the switch base.

While the switch shown and described thus far is of the type which is biased to return to one of its two positions following tripping thereof by means of the actuating button, the switch shown in Figures 7 and 8 is of the type wherein the contact blade will remain in either one of its two positions until it is actuated in the opposite direction. In other words, there is no biasing spring for returning the trip link or lever to the same position following actuation of the switch.

The construction of the switch mechanism in this case may be exactly the same as previously described, but an actuating lever 82 is provided instead of the actuating button to swing the trip link or lever 57 from one position to the other. The actuating lever is pivotally munted on the exterior of one longitudinal side of the switch housing, as by a pivot pin 83, to swing about an axis extending lengthwise of the contact blade of the switch and closely adjacent to the plane thereof. The lever may conveniently comprise a relatively flat thin piece of insulative material pivotally supported on the pin 83 and having a handle 84 projecting outwardly therefrom to provide for swinging of the lever.

The lever has a jaw portion 85 formed thereon projecting through a slot 86 in the adjacent longitudinal side of the switch housing, with the opposite fingers 87 of the jaw reaching around the adjacent longitudinal edge of the contact blade and loosely embracing the outer arm 60 of the trip link or lever 57 near its extremity.

In this case the two switch positions of the trip link or lever are defined by the actuating lever 82 which has inwardly facing shoulders 88 on its upper and lower side edges alternatively cooperable with a stop plate 89 on the adjacent side of the switch housing to limit the extent of rocking motion of the actuating lever. Thus, as illustrated in Figure 7, the barrel-shaped overcenter spring 66 is shown reacting upwardly against the outer arm 6%) of the trip link and through said arm against the upper finger 87 on the actuating lever to hold the same in its clockwise limit of rocking motion seen in Figure 8, defined by the engagement of its lower shoulder 88 with the stop plate 89. When the actuating lever 82 is swung in a counterclockwise direction as seen in Fig ure 8 the upper finger 87 on the actuating lever moves the trip link downwardly on its fulcrum past dead center and the switch snaps to its second position at which the barrel spring 66 reacting through the outer arm 60 of the trip link and the lower finger 87 on the actuating lever holds its upper shoulder 88 engaged with the stop plate 89.

With the exception of its housing and terminals, the switch shown in Figures 7 and 8 has all of the features of the switch shown in Figure 2.

From the foregoing description taken together with the accompanying drawings it will be readily apparent to those skilled in the art that this invention provides an improved overeenter snap switch featuring exceptionally good contact pressure even upon initial engagement of the contacts during tripping of the switch, and wherein no close inspection for tolerances of the switch parts is required; and that the arrangement of terminals and the housing construction generally greatly facilitates the znsembly of the housing sections and enables the parts of the switch mechanism to be properly engaged during such assembly of the switch mechanism.

What I claim as my invention is:

1. In an overcenter snap switch of the type including can elongated flatwise flexible contact blade having a fixed end portion and a free end portion movable toward and from engagement with a stationary contact, a housing for the switch comprising: an elongated base of insulative material having upright edges and having a recess in its top defining a low level support adjacent to one end of the base and a high level support adjacent to the opposite end of the base; a pair of terminals for the switch, each bent to substantially right angle shape from flat strip metal stock and each having one leg thereof fiatwise supported on one of said supports on the base and its other leg projecting downwardly through a notch in an adjacent edge of the base to the exterior of the housing so that the outer faces of said downwardly projecting legs of the terminals lie substantially fiush with the surfaces of said edges adjacent to the notches therein; rivets passing through said supports and the legs of the terminals thereon to fix said terminals to the base, the rivet through the low level support having a head providing a stationary contact exposed at the top of the base; the fixed end portion of the contact blade of the switch being secured fiatwise on said high level support in electrical contact with the leg of the terminal thereon by the other of said rivets, and the free end portion of the contact blade overlying and being cooperable with said stationary contact; and a cover for the housing secured over the base to enclose the switch mechanism thereon, said cover having a wall overlying the top of the base in spaced relation thereto, and having side walls closely telescoped over the upright edges of the base and the outer surfaces of the downwardly projecting legs of the terminals thereon.

i9 2. In an overcenter snap switch of .thetypeincluding an, elongated flexible contact bladehaving a'fixed end portion and a free endportioxi movable toward andfrom engagement with a stationary contact,.a.housing=for the switch comprising: cooperating upper. and lower elongated housing sections, theupper housing section providing a cover open at its bottom and having a top v.wall and downwardly projecting side walls, and the lower housing section 'cornprising a switch base telescoped into the open bottom of the coverv and having upright edges relatively closely slidingly engaged withthe inner surfaces ofthe cover side walls; means securingsaidhousingsections together .with the top of the base spaced from the top .wall of the housing; the baserhaving a recess in its-top defining a low level support adjacent to one end-of the housing and a high level support adjacent to the opposite end of the housing; a pair of terminals for the switch, each bent substantially to right angle shape fromfiat strip metal stock and each having one leg thereof ,flatWisereceived in a relatively shallow upright groove in one of said housing sections at the telescoping joint therebetween and projecting to'the exterior of 'the housing from the'underside thereof, and having its other leg flatwise seated on one of said supports on the bas and riyets passing through saidsupports and said other legs of the terminals thereon to fix said terminalsto:the--base,zthe rivet through the low level support having a head providing a. stationary contact exposed 'atthetop of'the base; the fixed end portion of the contact bladeof the switch being secured flatwise onsaidhigh-level support in electrical contact with the leg of the terminal thereon by the other of said rivets,- andthe free-end portionof' the blade being cooperable with said stationary contact.

3. The overcenter snap switch set forth in claim 2 further characterized by the provision of a second stationary contact fixed to the top wall of the housing directly over but in spaced relation to the first designated stationary contact and likewise cooperable with the free end portion of the contact blade, and a third terminal bent to substantially right angle shape from flat strip metal stock and having one leg secured to the top wall of the housing in electrical engagement with said second stationary contact and having its other leg extending downwardly through a relatively shallow groove in one of the housing sections at the telescoping joint therebetween to the exterior of the housing at its bottom.

4. The overcenter snap switch set forth in claim 3 wherein said second stationary contact comprises the head of a rivet by which the third terminal is secured to the top wall of the housing.

5. A switch device of the character described, comprising: an elongated housing of insulative material including a cover section open at its bottom and comprising a top wall and downwardly extending side walls, and a bottom section telescoped into the open bottom of the cover section to close the same, said bottom section comprising a switch base having a recess in its top defining a high level support adjacent to one end of the housing and a low level support adjacent to the other end of the housing; cooperating shoulders on the base and the cover section engaging one another to hold the top of the base in spaced relation to the top wall of the housing, said base having a pad projecting from one longitudinal edge, and the corresponding longitudinally side of the cover having a notch therein opening to the bottom of the cover to accommodate said pad on the base during telescoping of the cover onto the base and which notch is closed by said pad when the cover is properly positioned on the base with said shoulders on the housing sections in engagement with one another; means securing said housing sections together with said shoulders thereon in abutting engagement with one another; an overcenter snap switch mounted on the top of said base in the space between it and the top wall of the housing, said snap switch including a flatwise flexible contact blade having one end ,seate'dflatwise on and tfixedto said highlevel support anditsrother end portion overlying the low. level support,

.rnounted onthe cover section of-the housing witha por- ,tion normallybearingagainst thetriplinkto limit swingingmotion. thereof in one direction under theinfluence of said overcenter spring-so as to thereby preventdetachment of the spring fromthe trip link, said actuator having a portion extending through the cover .section of the housing and accessible at the exterior thereof; and-said notch in the side ofthe cover. accommodating a tool-by which the trip linkmay be held connected with the overcenter spring during'telescoping of the cover section onto the switch base to. a position atiwhich, said portion of the actuator is brought to bear upon the trip link.

-6.v In anovercenter snap switch: an elongated contact blademounted at one .end for. substantially fiatwisernotion of itsopposite end. portion along a defined path into .and .out of engagement with a stationary contact, said blade having an elongated opening intermediate its ends; a lever fulcrumedvat one end. adjacentto the mounted end of said contact blade andextending in substantially the same direction as the blade, said lever beingshorter than.-the contact blade and its outerend portion being movable along said path of travelof: the contact blade back. and forth through said .opening-inthe blade; an overcenter expansion spring confinedunder compression betweenvspaced outer end portions of the contact blade and said lever to yieldingly urge the blade in one direction and the lever in the opposite direction; and opposing spaced apart spring seats on the outer end portions of the blade and lever to receive the ends of the spring and hold the same operatively connected with the blade and lever, each of said spring seats comprising a tongue projecting into an aperture in the adjacent end of the spring and having opposite tapering side surfaces both of which are at ali times engaged by the adjacent end of the spring, said surfaces on the tongue diverging to a dimension larger than that of said aperture into which the tongue projects so that engagement of the spring ends with the blade and lever is limited to contact thereof with the tapering side surfaces of each of said tongues.

7. The overcenter snap switch set forth in claim 6 wherein said overcenter spring is a helically coiled expansion spring having annular end convolutions which provide said apertures into which the tapered tongues project to minimize the danger of the spring buckling during operation of the switch.

8. In an overcenter snap switch: an elongated substantially flat contact blade mounted at one end upon a support, and being fiatwise flexible to enable its outer end portion to be moved into and out of engagement with a stationary contact, said blade having an elongated opening intermediate its ends defining a bearing edge adjacent to but facing away from the mounted end of the blade and a spring seat adjacent to the outer end of the blade facing said bearing edge; a lever fulcrumed at one end upon said bearing edge for back and forth rocking motion through said opening in the blade so as to enable the outer end portion of the lever to be moved between alternate positions spaced to one side or the other of the plane of the blade, said lever being shorter than the blade and having a spring seat on its outer end in spaced opposing relationship to said spring seat on the blade, the fulcrumed end of the lever being wider than the opening in the contact blade and having notches in its opposite side edges into which edge portions of the blade along the longitudinal dimension of said opening project to provide an interlocking connection between the lever and blade to prevent accidental displacement of the lever from its fulcrum; and overcenter expansion spring confined under compression between said spring seats on the lever 11 and blade to yieldingly hold the blade flexed in one direction and the lever swung in the opposite direction; and means for moving the lever from one toward the other of said alternate positions thereof.

9. The overcenter snap switch set forth in claim 8, wherein said lever is stamped from a flat piece of sheet metal and said fulcrumed end thereof is rigid and has a crease therein into which the bearing edge on the blade projects to fulcrum the lever from the mounted end portion of the blade, said lever having a substantially flat outer portion which is substantially parallel and radial to the axis about which the lever swings, and said notches in the fulcrumed end of the lever extending into the opposite side edges of the creased end portion of the lever in line with the crease therein.

10. In an overcenter snap switch: an elongated con tact blade mounted at its rear end for flatwise up and down motion of its front end portion into and out of engagement with a stationary contact, said blade having an elongated opening in an intermediate portion thereof, the rear transverse edge of said opening providing a bearing facing toward the front end of the blade; means on the forward transverse edge of said opening defining a spring seat; a rigid lever formed as a stamping separate from the contact blade and having a short arm adjacent to the mounted end portion of the contact blade and projecting downwardly through the opening in the contact blade from one side thereof, said short arm having a transverse crease therein in which said bearing edge of the contact blade projects to fulcrum the lever for pivotal motion about a transverse axis parallel to the plane of the contact blade,

said lever having a long arm projecting forwardly from said short arm toward the forward transverse edge of the opening in the contact blade but terminating short of the spring seat thereon, and said long arm of the lever being movable up and down through the opening in the contact blade during swinging motion of the lever about its pivot axis to alternate positions at which the outer end portion of said long arm of the lever is disposed at one side or the other of the contact blade; means on the outer end of said long arm of the lever defining a spring scat opposing that on the contact blade; an overcenter spring connected between and confined under compression by said spring seats on the lever and the contact blade, for yieldingly urging the contact blade in one direction and the long lever arm in the opposite direction; and means for swinging the lever from one toward the other of said alternate positions of the long arm thereof.

11. The overcenter snap switch set forth in claim 10 further characterized by the fact that said long arm of the lever has an outer end portion offset downwardly and lying substantially in a radial plane containing the pivot axis of the lever.

References Cited in the file of this patent UNITED STATES PATENTS 2,556,216 Raney June 12, 1951 2,657,288 Hubbell Oct. 27, 1953 FOREIGN PATENTS 551,021 Great Britain Feb. 4, 1943