US2584460A - Snap action switch - Google Patents

Description

Feb.5, l195;.

P. c. JACOBS, JR 2,584,460

SNAP, ACTION SWITCH Filed De. 24, 1947 46 Eig-a.

55 44 /0 E8 ao law c. Jag.,

Patented F eb. 5,- 1952 SNAP ACTION SWITCH Philip C. Jacobs, Jr., Newtonville, Mass., assignor,

by mesne assignments, to The Acro Manufacturing Co., Columbus, Ohio Application December 24, 1947, Serial No. 793,687

(Cl. 20u-67) 7 Claims.

This invention relates to electrical snap action switches.

In snap action switches of the type herein disclosed it is desirable in certain installations that the force required to actuate a switch be very small, not more than an ounce or two. It is also desirable thatthe switch construction be such that after the blade has snapped from stable to unstable position, the amount of retreat of the operating button necessary to cause the blade to reverse itself,vmoving from unstable to stable position, be a very short distance.

In the switches now available in this art it will be found that the pressure that must be applied to the blade in order to cause actuation will be somewhere between four and twelve ounces. After the blade has snapped to unstable position, the operating lever must then be backed off at least .002 to .003 of an inch from initial actuation position before reverse movement of the blade to stable position will occur.

The invention herein disclosed provides a switch having all of the electrical characteristics of switches of the prior art but which can be operated on pressures as little as two ounces or less, with the general range being between one to four ounces. At the same time, the blade is so constructed that by backing olf the operating lever as little as .0005 inch',f'blade reversal will take place.

The novelty of the present invention resides in both the particular construction oi the blade and the combination of the blade with the supporting housing and electrical contacts.

The invention will be more clearly understood with the aid of the accompanying drawings, in

which Fig. 1 is a vertical sectional elevation showing the operating button in maximum depressed position and the switch blade in raised unstable position.

Fig. 2 is a vertical sectional elevation similar to Fig. 1, in which the operating button is in vmaximum upward position and the switch blade blade is mounted instill a different manner.

Fig. 7 is'an end elevation of Fig. 6, looking from the right.

, 2 Fig. 8 is a somewhat exaggerated view of the blade as shown in Fig. 2.

Fig. 9 is a somewhat exaggerated perspective view of the blade as shown in Fig. 1.

Fig. 10 is a side elevation of a blade similar to that shown in Fig. 5 but having a diierent point of support. a different position for the contacts,

perspective .and a different position for the force applying button.

Referring to Figs. 1-4, the switch comprises a housing 2 of insulating material, having a base 4 and a removable cover 6. These two parts are held rmly together by the nut and bolt 8, with the bolt passing through centrally aligned aperterminals 22 and 24, to which is secured the.

switch blade 26. This switch blade is of novel construction, and comprises a main body portion 28 having a hole 38 therethrough, through which passes bolt 8. The right hand end of the body of the switch blade has ailixed thereto upper and lower contacts 32 and 34, which are adapted to engage with contacts 20 and I8, respectively, as the body end of the blade may be moved up and down.

The left hand end of blade 26 has a pair of legs 36 and'38 extending from the body 28, which legs are drawn together or toed in and secured to an end plate 40 which in turn is rigidly ailixed to the terminals 22 and 24. Between legs 36 and 38 is a tongue or operating lever 42 extending from the body 28 and of such length thatV when moved vertically it will not be interfered with by plate 40.

The toed-in character of legs 36 and 38 produces a stressed area in the region indicated at 44. The more the legs are toed in, the more the blade will be stressed and .buckled at the area 44. The nature of this curvature is illustrated in Fig. 3, which is a section on the line 3-3 of Fig. 1, showing that when the operating lever 42 is in down position, as in Fig. l, the legs at section 3-3 and the stressed area 44 will be concave upwardly and the contact 32 in engagement with contact 20. The blade in the position in Fig. 1 is in 4 2 and thehole 39.--

When tongue-42 `as shown inFigs. 42 and 8 is 3 conditionandwill a sufllcient distance so that operating lever 42 moves upwardly past thecriticalfpoint, the

stressedl area u will cause the sides' of me body and adjacent portion of the legs to snap down# wardly, so that the blade at the stressed area 44 is l now, convex on 4its upper side andsimultaneously causing the right hand end of the bladeto snap remain there only so long as operating button 46 is held'ina' suf-' flciently depressed position. When the operating button is released or allowed to move upwardly 1.

l force has been applied to the operating lever downwardly, putting contact I4 in engagement with contact I8, as shownin Fig. 2.

vReference to Figs. 8 and 9 will aid in a better understanding of the character of the stressed area. The legs 361 and 3 9', being toed in, 'produce a normal Ainner edge' buckling and an outer edge tension condition over the general area where they connect Awith the body. At the Sametime,

thetoed-in legs cause the body inthe immediate.

vicinity to be arched upwardly 'or downwardly according to the stressed position the blade has been placed in. The tongue or:lever 42 is on the convex side ofthe body.

L It will be understood that the toeingin of the legs causes a stressing of the area of the body adjacent theends of the legs and tongue 42. This area is generally indicated as -at-44' and, as illustrated infFig. 8, will be convex on itsfu'pper side 'and concave on itsunderside. AThe entire area which includes` the stressed area of the legs and the body will be formedwith a compound curvaturewith the center of the relatively flat arch so formed some place between the end o f tongue pressed downwardlmthe stressed area at the end of the tongue Vbe forcedv through neutral position, thereby changing the direction of the stresses'so that the blade substantially instantaneously'reverses'itself to assume the position shown in'Flgs. 1, 3 and 9. In lthis position the upper side of the blade is concave'and the lower side convex at the stressed area. The blade, when in this position, will presenta flat dished area extendingaway fron'i the center of area 44 to forma compoundcurved section in the nature ofV an inverted shallow arched member which resists deformation inall directions. v

It be understood that the Aexact limits of 42v other than the weight of button 46, will be in stable position, with contacts v34 and i8 in engagement, as shown iriFig. 2. When operating button. has-been depressed a maximum amount,

with operating lever'42 in contact with stop 48.

I as shown in Fig. 1. blade 26 will be in raised unquired will be reduced.

stable position, so that upcn release of operating lever 4 2 the blade can -r'eassume normal stable position shown in Fig. 2.

Operating button 48, generally hemispherical at the engagingyarea and having a stem 41 which extends through a suitable opening in cover 6. is shown as engaging operating lever 42 at a point an appreciable distance to the right of the left end of the operating lever. It will4 be understood, however, that this position of en- If it is moved toward the end of lever 42 the total over- 'all movement of button 4i required to effect actuation will be increased but the pressure re- Conversely, if the point of engagement is moved toward the stressed area 44, the extent of the required movement of the button will be less before actuation occurs, but more force will be required. In switches that have been tested, the force required to cause actuation, when applied at the left end of operating lever 42 will bein the order of 50 per cent of "the force required at the base of operating lever 42.

After'actuation of the blade, the extent of the .retreat necessary to cause the blade to return the tongue, decreasing gradually as the point at which the force of the operating button is moved the stressed area cannot be.accurately dened as the limits .vary with the degree thejlegs arev toed-in. Themore thelegs are toed-fin, the

greater the stress and the greater the area over f which the stress isapplied, 'and a correspondingly vgreaterffor'ce vwill be. required to cause reversal of the blade from the position of Fig.A 8 to the toward the free end of the tongue.

. If the point of application of the force is gradually moved in the direction of the stressed area. it will be found that a point will be reached where the blade will not function to snap upwardly, but, on vthe contrary, contacts 34 and I8 will be forceably maintained in engagement, even though the stressed area 44 is depressed and has snapped a to .a position-in which the concavesideis upposition of Fig. 9. In allcases,however, the ve'tfec-` -In a typical switch construction, `the vblade I 'will be limited in its movement in one direction by a stop. or contact sothat when actuated, it cannot reach the second stable position. Thus in the arrangement shown in Figs;v 1 and 2, contact 20 checks upward movement of blade 26' an upward stable position be reached for if thisl i. tive center of the stressedarea in the body porl tion be relatively close4 to the end of tongueV ward.

. From the foregoing description it will be unv struction disclosed results in thev return 0f the switch to stable .position upon'very slight upward movementof lever 42 from the position which caused initial actuation. Thatis to'say, if we consider theposition of the Darts shown in'Fig. 2 as the starting position, then'lever 42 will be increasingly deflected downwardly as pressure is exerted on button 46 until a certain critical point were the case, the blade would not return of its. own volition to"v the initial stable position against contact AIl upon release of operating butis reached. At this point, the blade will snap to and remain at the position' of Fig. 1 without further movement of button' 40. If button 4I' is maintained in this position,thevswitch blade will continue in the positionof Fig. 1, with the contacts in suitable engagement for proper passage of current..

When button 48 is moved in the reverse vdirection, that is, upwardly, itwill be found that upward movement oi' the button of less than .001 inch will be suilicient to cause the switch blade to reverse itself and snap to the stable position of Fig. 2. i

Stated in other words, button 48 may be actuated up and down over a distance of not more than .001 inch to produce complete actuation of theblade. As can be understood by those familiar with this field, this is a substantial advance in the sensitivity of snap action switches of this general type. v

The distance that the button must move to cause actuation in both directions will vary somewhat as the applied force is shifted along the tongue. The movement will be greater toward the body end and less toward the free end. The force required to move operating lever 42 to the critical point at which the blade snaps to up position is likewise reduced below that of switches of the prior art. This force may be in the order of one or two o'uncesdepending on the blade construction and point of force application. After actuation, the force required to hold the switch blade in unbalanced position may be as little as half of the force originally required to cause actuation.

The stressed portion 44 of blade Y28 shown in Figs. 1-4 has been produced by toeing in legs 38 and 38 and holding them in that position by plate 40. If desired, however, the blade may be made ilat without any toe-in to the legs. Thereafter the blade may be struck with a concavoconvex die so as to deform and stress the area 44 to produce a condition substantially the same as that obtained by toeing in the legs. Both methods are equally effective in creating a satisfactory snap action in the blade. Furthermore, the blade may be of one piece throughout with the end plate l40 being integral with the legs 38 and 38. End plate 40, partially split as at 43 as shown in Fig. 4, has the desirable. characteristic of being capable of being squeezed together or spread apart to vary the toe-in of the legs and thereby vary the stressing of area. 44 and thus varying the force required against operating lever 42 to cause actuation.

In Figs. 1-4, the blade is shown as being anchored at the ends of legs 38 and 38 with the contacts 32 and 34 on the opposite movable end of the body 28 and with actuation caused by pressure against operating lever 42. If desired, however, this arrangement may be reversed, as illustrated in Fig. 5. Here the contacts 50 and 52 are xed to the end of what in Figs. 1-4 was operating lever 42, while button 48 is arranged to press against the end of body 28. The toed-in legs are mounted as in Figs. '1-4 on contacts 22 and 24. The stressed area 44 is in the same relative position' between the end 54 of the body which formerly carried contacts 32 and 34 and the former operating lever 42 which now carries the contacts.

The construction of Fig. 5 could be used Where it is desired to reduce the operating force lrequired still more, although the overall movement of operating button 48 will necessarily be somewhat greater.

A further modification of the supporting arlegs.

6 rangement is illustrated in Figs. 6 and 1. in which the blade is mounted by afllxing the operating lever 42 of Figs. 1-4 to the housing by a supporting contact 58. The contacts, of which there may be one or two sets, as illustrated at 88 and 88, are placed on the 4ends of the legs 38 and 38, while the operating button presses against the far end of the body as at position 82. The blade otherwise is the Vsame as that illustrated in Figs. 1-5. having the usual stressed area at 44.

Another modication is illustrated in Fig. 10. In this form, the blade is similar to that shown in Figs. 1 to 7 b'ut diers as to the positions of the mounting, contacts and operating button. The

button 12 is pressed downwardly, operating lever A 42 will likewise be moved downwardly to cause the legs 'to reverse their positions bysnapping upwardly, thereby shifting contacts 88 and 88 from down to up position. The blade 'has the usual stressed area 44 located at the junction of the operating lever 42 with the body 28.

Thus, in all of the figures the blade is the same, having a body, a stressed area in the body, two legs and a tongue, or operating lever, between the The contacts may be placed either on' the body end of the blade, as in Figs. l-4, the operating lever, as in Fig. 5, or the end connecting the legs, as in Figs. 6 and 10. If the contacts are on the end of the body, the blade may be supported at the ends of the legs and the pressure applied to the operating lever, as shown in Figs. 1-4, or the blademay be supported at the end of the operating lever and the -pressure applied to the end plate or cross bar that connects the. ends of the legs.

. If the contacts are positioned on the ends of the operating lever, then the blade may be supported by the end plate, as in Fig. 5, and the force of the button applied to the end of the body, 01 the free end of the body may be supported and the force applied to the end plate connecting the legs.

If the contacts are attached to the end plate that connects the legs, then the blade may be supported at the end of the body and the force applied to the operating lever, as in Fig.-10, vor the blade may be supported at the end of the operating lever and the force applied to the end of the body, as in Fig. 6.

In all three situations the snap action will occur, the force required will be very small, and the return to stable position will take place upon very small return movement ofthe force applying button.

It will also be understood that the length of the operating lever 42 may be varied within reasonable limits Without affecting the principle of operation, so long as the stressed area 44 is present.

Also, the presence of hole 30 does not aiect the operation so long as there is adequate surface to form a suitably stressed area 44. If dsired, the housing may be assembled in a different manner, so that bolt 8 may be omitted, with hole 30 in the blade likewise omitted.

While preferred forms of the invention havel 7 been described and shown will be understood that I do not intend to be limited thereby, but only by the appended claims.

I claim:A

l. A snap action switch comprising a base, a pair ofy spaced contacting members at one end of said base, a support at the other end of said base, said support having rigidly amxed thereto a switch blade, said blade comprising a movable elongated body portion having contacts on opposite sides of the end thereof, which contacts are positioned between said spaced contacting members; a pair of legs extending from said body portion, the ends of said legs being secured to said support, a tongue extending from ,said body between 'said legs and being movable at its free end,'said body having a single stressed area with a compound curvature adjacent said tongue and extending into said legs a limited distance, said stressed area being remote from said contacts so that in stable position one of the said contacts on the end of said body will press against one of Asaid spaced contacting members' means for applying a 'force against that side of the tongue which is opposite the contact and contacting memberthat are normally in engagement wherein the drawings. le

between saidlegs, said body. portion having a single stressed area with a compoundcurvature by said tongue may be moved to cause said stressed area to reverse itself and to cause said normally engaged contact and contacting mem- -berto separate and the other of said contacts on said body to engage the other of said spaced contacting'members, said other of said spacca contacting members being located to hold said body portion in unstable position, lwhereby when said forcev is partially removed from said tongue said stressed area and body of the blade will reends of' saidlegs being securedto said support, I

a tongue' extending from said body between said legs, said tongue having contacts on opposite immediately adjacent said tongue and extending sidesof the free end thereof, which contacts are positioned between said spaced contacting members, said body having a single stressedarea with adjacent said tongue 4and extending into said legs a limited distance so that instable position tact and contacting member to separate and the vother of said contacts on said legs to engage the other of ,saidspacedv contacting members, said other of said spaced contacting members being located to hold said legs in unstable position, whereby when said force-is partially removed from said tongue, said stressed area and said legs will return to stable position.

4. A snap action switch comprising a base, a

switch blade secured in a stable position on said base with-partthereof movable, a pair of spaced ilx'ed members of which at least one is a contact straddling a movable part of said switch blade,

said switch bladecomprsing three parts, said parts being an elongated body portion, apair of legs extending from said body portion and a tongue extending from said body between said legs and terminating in a free end, said blade having a single stressed area with a compound curvature in said body portion, said stressed area being relatively small in relation 'to theA total area of said body portion, said area being located fromv side to side of said body portion and into said-legs-a limited distance, a contact on that part of saidy blade that is between said spaced fixed membersand in engagement with one o f said xed members, and means for applying a force to that part of said bladeV that isnot secured to said base and does not include vsaid contact whereby upon applicationof said force said stressed area and that `partf of the blade including said contact will be'caused to snap `from stable position to unstable position -wt'n acompound curvature adjacent said tongue and extending into said legs a limited distance so that in stable position one of the said contacts on the end. of said tongue will press against one of said spaced-contacting members, means for applying a force; against that side of said body portion'which is opposite thev contact and contacting said contact in engagement with the other of saidxed members. f 5. A blade for use 'in' a snap'action switch',l

. comprisingan elongated body portion, a pair vof memberthat are normally in engagement. whereby said body portion maybe moved to cause said stressed area to reverse itself and to cause said normally engaged contact and contacting member to separate and the other of said contacts on said tongue to engage the other of -said spaced contacting members, said other of said spaced contacting members being' located to hold said tongue in unstable position whereby when said force is partially removed from said body portion,

rigidly afiixed v thereto `a switch blade, said blade legsextending therefrom'with the outer edges Y of said legs forming a continuation of the side edges of said body portion, a movable ,tongue free end, aL-'single reversible stressed area'with a compound curvature in said body portion adja- -cent the body portion endoi said tongue, said stressed area extendinginto said legs a limited distance, said stressed area being subject to re'- versal fromconvex to concave upon the movefm1 te the plane of theblade and beyond a erin.-

* cal" point, said tongue in its movement with respect 4to said legs always being inthe direction' of theconvex side of saidstressedrarea.

comprising abody portion which isgsecured to said support, apair of movable legs extending from said body portion having contacts on oppo- 6. Avblade for use in a snap action switch, as set forth in claim 5, in which said legs have been drawn together at theirend's beyond the/position they would normally'assume and secured by 'u a' connecting plate, thereby deiorming part of ment of either the body portion, legs vor tongue l. relative to the'two in a direction generally -norsaid body portion to produce said stressed area adjacent said tongue.

7. A blade for use in a ,snap action switch, comprising an elongated body portion, a pair or legs extending therefrom with their outer edges forming a continuation of the side edges of said body portion, a connecting portion comprising an end plate adapted to serve as means for mounting said blade joining the ends of said legs, a tongue extending from said body portion between said legs and terminating short o1 said connecting portion, a stressed area in said body portion commencing at the body end of said tongue and extending laterally to the edges of said body portion and away from said tongue toward the remote end of said body portion for a limited distance and into the said legs for a limited distance, said stressed area being dshed and having in normal position curvature both longitudinally and transversely, the stressed area tapering into an unstressed area at the remote end of said body portion, said stressed area being subject to reversal from convex to concave upon the movement of either the body portion, legs or tongue relative to the other two in a.l direction generally normal to the plane of the blade and beyond a critical point.

L PHILIP C. JACOBS, Jn.

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

UNITED STATES PATENTS

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