US2370479A - Switch mechanism - Google Patents

Description

Feb. 27, 1945. E. P. MEYER 2,370,479

SWITCH MECHANISM Filed Jan. 28, 1944 Peieniedreb. 27, 1945 UNITED STATES PATENT OFFICE 2,31'02479 f SWITCH MECHANISM Edward P. Meyer, Freeport, Ill., assignor,A by mesne assignments, to First Industrial Corporation, Wilmington, Del., a corporation of Delaware Application January 28, 1944, Serial No. 519,985

3 Claims. (Cl. 20D- 67) This invention `relates to switch mechanisms and more particularly to switches of the precision type having low operating pressure and a, small.

operating movement. 'With switches 'of this type a serious prob-lem is that of producing a sharp and clean break of the contacts without bounce and with an unwavering and direct movement of the parts. This is particularly diflcult in" switches of the type having a switch spring mounted at one 'end in cantilever fashion with the other end movdependently thereof and are supported on an 'v auxiliary lspring support imparting a secondary movement to the contacts to maintain the` mobile contacts in engagement-with the stationary contacts a short interval after the start of movement of the main switch spring, and likewise to bring the contacts into engagement a short interval before the main switch spring completes its movement, and wherein the resilient mounting of the mobile contact is such thatv the aux iliary spring is completely unloaded at the time contact is made witheither an upper or a lower contact. i Other objects and advantages will appear from the description and the :accompanying drawing, in whichf vFigure 1 is a longitudinal section througha switch embodying my invention showing the mobile contacts engaging the upper contacts of the switch;

Fig. 2 is a View similar to Figure 1 showing the mobile contacts engaging the lower contacts Yof the switch;

Fig. 3 is a section substantially on the line 3-3 of Figure 1; n I Fig. 4 is a top View cover and the upper stationary contacts removed; and l Figs. 5 and 6 are enlarged views partly in 'section taken through the stationary and mobile contacts showing the relative positions, of the mobile contacts and the switch springs in the two positions of Figs. 1 and 2.

f The invention as herein shown is embodied in a molded plastic case having a body 8 and 4a I' sired electrical circuits.

withfthe operation of the switch mechanism. Carried in the cover is an actuating plunger I2 operated from an actuator button I3,lin this instancean over-travel mechanism being disposed therein butforming no part of the present invention.v The actuating pin I2 carries a plunger head Ill` preferably of insulating material adapted to engage :and operate the switch spring, as will presently be described. Fitted into the oppositeA end of the housing 48 are'ferrules I5 adapted forthe reception of screws I6 arrangedy at their lower ends to retain electrical connector brackets ll lagainst the bottom of the body il and at their uppery ends to secure stationary or vfixed upper contacts I8 and I9 in position against spacers QI disposedywithin the vchamber II against an abutting surface 22.i The screws I6 thus serve to secure theupper stationary contacts in position, to hold the brackets I1 in position and to form an electrical connection therebetween.

Likewise molded or otherwise suitably secured inthe bottom of the body 8 are ferrules 23 spaced transversely pf the housing adapted to receive screws y2,4 which hold lower stationary or xed contact members 25 and 2'5 in position, these lower stationaryy contact elements extending upwardly and outwardly into spaced relation with the lupperstationary contacts I8 and IS. The ferrules 26are also provided with screws 21 adapted k,for the connection thereto of electrical conductors for connecting the switch into the de- A femme 21a is molded into thebody s adjacent the end thereof opposite the ferrules I5, the upper end of the ferrulebeing flush with a shoulder 29 of the body. Seated on the upper end of the ferrule and against the shoulder 29 is of the switch showing the anlanchor plate indicated generally by the numeral 3Iy having spaced anchor legs 32 and 33 extending toward the center of the' chamber II alongopposite sides of the body, as wil1 be ap` parentfro-m Fig. 4. Positioned on the top of the anchor plate 3| is an end 34 of a tension member 35 presently tobe more fully described, a washer 36 being disposed above the end 34 and a screw or bolt 31 passing therethrough,

through the ferruie 2a and e. nut 39, e tab 4| cover 9 seated over the body in intertting relabeing disposed between the nutl 39 and the ferrule, the screw thus serving to hold these parts in iixed relationship with respect to each other and the bottom of. the body 8. The tab 4I serves for connection of the tension member k35 into an electric circuit if desired.

l The tension member 35 forms part of a main snap springsuch as that described ln McGall Patent 1,960,020,`mounted in cantilever fashion,`

this spring being formed of suitable metal such, for example, as beryllium copper and having in addition to the tension member 35, spaced cornpression members 42 and 43 of somewhat lesser length than the tension member 35, th'e compression members and the tension member being interconnected at the free endof thespring as shown at 44. The opposite ends of the compression members 42 and 43 are pivotally supported in notches in the ends of the anchor legs 32 and 33, as described in said McGall patent.

It will be seen that:4 with this construction, when the button I3-is depressed so as to force the head I4 downward and ,move `the tension member 35 through the axis of maximum compression of the spring system and beyond the point at which the compression members- 42 `and 43 are carried in the anchors, the free end 44 of this mainsprin'g system ,will snap from the position shown in Figure l to the position shown in Fig. 2.

As will be seen from Figs/1 and 2,'the yfree end 44 of the main spring is -disposed'between the stationary contacts I8 .and I9 and the stationary contacts 25 and 26,so that when the plunger isdepressedthe free'end snaps toward the contacts 25 and 26'and when the plunger is released the free end snaps back toward stationary contacts I8 and I9. "Carried on the free end 44 of the main snap spring isa trifurcated or W-shaped .auxiliary spring designated generally ,by the numeral 45 having a "central leg 46 and gradually stressed until the main spring seats against the back of the heads 54. The modulus of elasticity of the auxiliary spring is so related with respect to that of the main switch spring that when the contacts come into engagement, the auxiliary spring will flex suiiciently to maintain the contacts in engagement in spite of the rebound of the free end ofthe main spring. The precise value cannot be given because it will vary considerably with different switch designs and should be determined for each design by sample tests well known in the art. Thus, any bounce which may occur as a result of action in the `main switch spring will result simply in the main `spring leaving contact with the back of the heads 54 and its vibration will occur without the face of the mobile contacts being disengaged from the sides.

spaced side legs 41 and 48, the auxiliary spring extending backward in superimposed relationship'over the main spring, as will be apparent from the drawing.- The free end of the central leg 45 is vwelded, brazed orotherwise attached to the central portion of the free end 44 as shown l stationary contacts. The electrical circuit is maintained through any such movement by Way of the auxiliary spring. Wherefdouble contacts are lused 'so that. thefheads 53 and 54 function .to bridge between twofcontacts in each position (a contact construction Well known in the art) the auxiliary spring mounting of the mobile contacts functions to compensate for small irregularities in the level of the fixed contacts and insures substantially simultaneous break on the two Likewise it will be seen that the `auxiliary spring compensates for differences in the level of the contacts 25 and' 25 or-the contacts I8 and I9 by exing about a longitudinal axis through the switch, and likewise insures a substantially simultaneous break as between the two mobile contacts and their vrespective stationary contacts.

- I claim:

` l. The combination in an electric switch .of a ymain switch spring mounted at one enclin cantilever fashion having a free end, means for ilexbetween opposed positions with a snap action, an

. auxiliary `spring having a central leg xed to contacts being lixedto the legs and each of the contacts `comprising spaced heads 53 and 54 (Fig. 6l interconnected'by a'shank 55, the free end 44 of the main spring having openings of such size as to permit the freey passage of the `Shanks but of insufficient sizento permit the passage of the heads. It will thus be seen that the contacts 5I and 52 are supported on the `main spring y through the resilient side arms 41 and 48 and the central arm 46 so that the contacts have re-v 44 and with respect toeach other.

The auxiliary spring y45 is -so arranged 'and Y mounted that in its unstressed condition the 4free end`44 occupies Va 'position substantially midway between the contact heads-"53 and 54 'and such that the auxiliaryyspring is completelylunloaded As the Yplunger is depressed beyond '65 y l strained movement with -respect to the free end 53 and continues'to move with a continuous action during the snap, Vthe auxiliary spring maintaining the heads 'in engagement substantially until the auxiliary spring'isunstressed. Upon continued movementthemobile contacts ap? proach the stationary contacts 2'5` l'and`26 andas they reach these contacts the auxiliary spring is said free end and side legs disposed on `opposite rsides thereof, -said legs being interconnected,

`mobile contacts into engagement with said iix-ed `contacts While :the auxiliary spring is unstressed.

Y2. lThe combination in an'el'ectric switch of a main switch spring mounted at oneend 4in cantilever fashion and having a 'free yend, means lfor llexing said spring to cause the free end 'to ymove between opposed positions with a snap action, spaced iixed Acontacts yadacent said free `end de ining opposed positions of said free end, a forked auxiliary spring overlying said free end having a plurality ,ofl legs interconnected at one end,

'the unconnected end of one leg being attached to said ireeend, at least one mobile contact 'carried on the unconnected lend vof the other of said 'leg-s, V'said mobile contacthav-ing yspacedheads anda shank of greater length than the thickness of said f ree end vpassing freely through said free end and interconnecting said heads, sm'd faux- `ili`ary spring ibe'ing shaped, finunstre's'sed lcondi- `tion,`to support said heads-in spaced relation to opposite sides of said free end, for engagement mobile contacts each having spaced heads and a and disengagement of said mobile contact with said fixed contacts at points in the travel of said main spring at which said auxiliary spring is unistressed, in response to movement of said main spring to either of said positions, and means for.

actuating said main spring to cause said free end to move to said opposed positions bearing against the heads of said contacts to stress the auxiliary spring and hold the mobile and fixed contacts in engagement.

. 3. The combination in an electric switch of a main switch spring mounted at one end in cantilever fashion having va free end, means for flexing said spring to cause said yfree end to move between opposed positions with a snap action, an auxiliary spring having a central leg fixed to said free end and side legs disposed on opposite sides thereof, said legs being interconnected, mobile contacts carried on said side legs, said shank interconnecting said heads having passage through said free end and having a length greater vthan the thickness of said free end, one of said flex and thereby maintain said mobile contact in engagement with the xed contact upon rebound of said free end incidental to snap movement of said end into said opposed positions.

EDWARD P. MEYER.

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