US2782277A

US2782277A - Snap-action switch

Info

Publication number: US2782277A
Application number: US258655A
Authority: US
Inventors: Ralph B Immel
Original assignee: Westinghouse Electric Corp
Current assignee: CBS Corp
Priority date: 1951-11-28
Filing date: 1951-11-28
Publication date: 1957-02-19
Anticipated expiration: 1974-02-19

Description

Feb. 19, 1957 R. B. IMMEL 2,782,277

SNAP-ACTION SWITCH Filed Nov. 28, 1951 v Insulation 28 2 6 52 1 1/5 5| Fig.2.

INVENTOR Rqlph B.Imme|. BY

' ATTORNEY United States Patent v 2,782,277 SNAP-ACTIONSWITH :RalpheB. I mmel, winiams nie, 'N. Y; assignorto- Westinghouse vElectric. CorporationQEast PittsburghfPa a corporation Pennsylvania ApplicatiomNovember 28, 1951,1e'riafNo.25iii655 13 Claims. (Cl.1200-f-67) My invention '-relates, --generally, to electric switches sand, -more pa'r'ticularly,to switches er 'a type *which operate witha snap-action.

3 Relatively small control switches and limit switches -are -frequently-' required insystems-for automatically con- -trolling the-operation of machinery. "For such industrial =-applications, reliability "and "precision of operation at the same "point-in 'the travel'of theswitch-operating "member are important features.

An object-of my invention, generally statcL-is-to provide a snap-acting switch which is' simple and reliable Inaccordance with one embodiment of my invention .the bridging contact member of.a snap-action. switch 'is connected to a pusl1'-button operator bytoggle' levers whichalso function 'asi spring members under stress to ,provide a'forceforlholdinglthe moving contacts against "the stationary contacts, thereby insuringa relatively high contact pressure. When'the push button' is actuated, .the

'springmem'bers arefstressed'further until they go overcenter, thereby operating "the bridging contact member 'zwith a snap "action.

'For a better understanding of "the naturev and objects .of .the. invention, reference may be ha'dtdthefollowing "detailed description,'taken in conjunction with'the accompanyingflrawing in which:

*Figure '1 isa'viewjin'sideelevation, of a switch.em- I'bodying the p'rincipal features of the invention,.the switch 1casing cover being removed;

Fig. 2' is anenlarge'd .andexplode'd view of certain parts of the switchfthe parts being showninperspective;

Fig.3 is a view,-in 'side elevation,-.of amodifiedfform of switch, with .part of the casing'being'broken away;

arid I "Fig. 4 ..is a view, similar toFig. .2, ..of.parts of the switch shown in 'Fig. 3.

FRferring to ...the .drawing, and ..particularly -toiEigs. 1-.-and,2, ..the -switch structure -shown thereincomprises a' base. It), which maybe moldedtfrom asuitable insulating material and a .cover.(not.shown) which maybe attached to "the base '10 by bolts or .rivets inserted through'openings 111 providedinthe base '10. Asshown, the. base 310'. has an opening 12 therein for .a. reciprocating operating member. 13 Lfonactuating the. switch mechanism, as'w'ill be described more fully'. hereinafter.

2 Two pairs of oppositely-'disposed cont-act blocks-14 'aremounte'd in the base 10. The contact' blo'cks 14' may be" composed of any" suitable electrical conducting 'ma- -'terial. -Each contact blockhas-an integrally formed-pin '15=w-hich is-in'serte'd -in--a suitable opening provided in the base 10. As shown, th'frontcorners of each block are cut away to provide shoulders ld which are engaged by the cover of the casing to retain the contact blocks in position. A contact 17 is provided on-each contact'block 14. The contacts 17=arejpreferably composed of" silver -or 'asilver alloy. -A threadedopehing 18"isprovided in 'the"front" eridof each contact block "for'receiving a threaded screw 19 for'making'an electrical "connection to the contact block.

A' bridging contact member "21 is movably disposed between the "upper"- pair of contact "blocks 14 and "the lowerpair of contactblocks. As shown most clearly in Pig. 2, the bridging contact member 21 is generally rectangularin'fshape and has a generally rectangular '-opening"22itherein. The"member"21 may be 'formed from a reiativ'elyi'thinl sheet ofconducting material, such as berylliumJcopper. 'The rigidity of'the .member "21 may' be increased by. providing'downwardly turned flanges '23 at 'itsfouter edges and similar flanges 24 at the sides oflthe rectangular opening'22. 'In. this mannerjthe contact member fii may'be relativelylight in weight'but at the same time relatively rigid. "Thus; the contact member 21 has a low inertia and can be operatedwith a fast snap action. The bridging contact member 21 is provided withupper andlower contacts 25 at eachend which are disposed to engage the contacts. 17-011 the contact blocksld. L'Thecontacts 2 5 areprferablycomposed of the samematerial 'as the contacts 17.

As shown, ..the switch-operating member13-is in the form .of .a push button,.-and it may be moldedfrom a suitable .insi1latingmaterial. .The top of the push but- .-ton .is rectangular in section, and the reciprocating .movement off-thepushbutton is guided bythe sides of :the. rectangular openingw 12in the baselil- A flange-26 .is. provided.at thenbase of -the1push button to-engage .shoulders 27 onethe base It? to limit the upward movement of the push button13. -A guide pin 28 extends downwardly from the push button :13 intoan opening "291 in the :base 10, thereby also .-.guiding the movement of. the push-ibutton.

Ascoilspring-31*s-urrounds the guidepin 28 and :both members extendthrough the opening -22.'in the bridgingcontact member 21. The lower "end of the spring 31 rests'on shoulders 32 on the base/10, and :the UPper nd of the spring'lal' engages a clevis33 which is also m0unted-0n th guide pin 28. The clevis 33 has Janopening :34 therein for receiving the :guide pin- 28. In this mannerthetsprin'g 31 is compressed when the push-buttoni1-3 :is pressed downwardly, and it returns thetpush button liito its uppermost" position when it is released.

As shownmost clearly :in'Fig. :2, the clevis33 has two downwardly extending spaced arms 35 each of which :has a-=bearing:notch-36 near its lower end. Two resilient spring toggle levers 37 are disposed between the arms 35 50151116 clevis 33-andtheends ofthe rectangu- .lar opening 22 intbe bridging contact member Zl. 'As shown most clearly -in Fig. 2,:each ofthe toggle mem- .bers 37 isggenerallyzof a U-shape and may be'-formed from a relatively thick piece of resilient spring material, :suchas spring steel.

One leg of "therU-shaped member'37 has a flange 38 thereon having ar notch 39 therein. The other leg'has ia.notch1'41 in each lside edge of the leg. .A notch 42 is gprovidedin each end of-the opening 22in thebridging :contact member -21. The *switch mechanism may. be assembled by placing the notches 41 of the toggle members in the notches 42 in the bridging member 21 and placing the notches 36 in the clevis 33 in the notches 39 in the toggle members 37. Since the distance Z between the bearing notches 42 is'less than the sum of the dimensions X +21, the spring toggle members 37 are stressed when assembled in the switch mechanism. As shown, the dimension X is the distance between the arms 35 of the clevis 33 at the bases of notches 36, and the dimension Y is the distance between the bearing

notches

39 and 41 in the legs of each U-shaped toggle 37.

As shown in Fig. l, the push button 13 is normally biased to its uppermost position by the spring 31 and the bridging contact member 21 is normally biased to its lowermost position by the spring toggle members 37 which, as previously explained, are stressed at all times when assembled in the switch mechanism. Thus, the contacts 25 on the bridging member 21 are held against the lower contacts 17 with suflicient contact pressure to enable the contact members to conduct relatively heavy currents. 7

When the push button 13 is depressed, the spring toggle levers 37 are stressed still further until the ends of the levers which are engaged by the arms 35 of the clevis 33 pass overcenter, thereby causing the bridging contact member 21 to be actuated upwardly with a fast snap action. The upward movement of the bridging contact member 21 is limited by the upper contacts 25 engaging the upper contacts 17. The spring toggle levers 37 are still under stress, thereby maintaining a good contact pressure between the upper contact members.

When the push button 13 is released, the return spring 31 returns it to the position shown in Fig. 1, thereby actuating the bridging contact member 21 downwardly by stressing the toggle members 37 until they pass overcenter. Thus, a snap action is obtained during operation of the bridging contact member 21 in either direction.

It will be observed that the knife-edge bearings 42 in I the member 21 are sutficiently far apart to overcome any tendency of the member 21 to rotate about the guide pin 28 as a center, thereby reducing friction between the moving parts of the switch mechanism. Furthermore, the parts of the switch mechanism are relatively simple in structure and require that only the X, Y, and Z dimensions be maintained with relatively close tolerances during the manufacture of the parts.

The switch shown in Figs. 3 and 4 is somewhat similar in structure to the one shown in Figs. 1 and 2. A base 50, which may be molded from a suitable insulating material,

has openings 51 therein for attaching a cover (not shown) to the base. A rectangular opening 52 is provided in the base for receiving a push button 53. Contact terminals 54 are so mounted in the base as to be accessible from the bottom of the switch instead of from the side as in the switch shown in Fig. 1. As shown, each outer terminal 54 has a U-shaped bracket 55 attached thereto. The bracket carries a contact 56. Each inner terminal 54 has a bracket 57 attached thereto which supports a contact 58 disposed below a corresponding contact 56. Terminal screws 59 are provided in the terminals 54 for making electrical connections to the terminals.

A generally rectangular bridging contact member 61 has a generally rectangular opening 62 therein. The member 61 is preferably composed of the same material as the member 21, and it may be provided with flanges 63 at its outer edges to increase its rigidity. Upper and lower contacts 65 are attached near the ends of the bridging member 61. The contacts 65 are preferably composed of silver or a silver alloy as are the contacts 56 and 58.

As shown, the push button 53 is rectangular in shape and has a flange 66 at its base. The flange 66 engages shoulders 67 in the base 59 to limit the upward movement of the push button. A guide pin 68 extends downwardly from the push button. An opening 69 is provided in the base 50 for the lower end of the guide pin 68. Thus, the

4. reciprocating movement of the push button is guided by the sides of the

openings

52 and 69 provided in the base 50.

A coil spring 71 surrounds the guide pin 68 with the lower end of the spring resting on shoulders 72 in the base 50. The upper end of the spring 71 engages a connecting bar 73 which connects the inner legs of generally U-shaped spring toggle members 74. A guide plate 75 having downwardly extending flanges 76 may be disposed between the connecting bar 73 and the push button 53. The push button 53 may be provided with a groove 77 for receiving the guide plate 75. The guide plate 75 has an opening 78 therein, and the bar 73 has an opening 79 therein through which the guide pin 68 extends.

As shown most clearly in Fig. 4, the U-shaped spring toggle members 74 are formed integrally with the connccting bar 73. Bearing notches 81 are provided in the :outer legs of the Ushaped members 74. A bearing notch 82 is provided in each end of the opening 62 in the bridging contact member 61. The toggle members are assembled with the bearing notches 81 placed in the notches 82. Since the dimension Y, which is the distance between the outer ends of the U-shaped toggle members, is greater than the dimension Z, which is the distance between the ends of the opening 62, the toggle members are stressed at all times when assembled in the switch. Thus, they function in the same manner as the toggle members 37 to maintain contact pressure between the contact members of the switch.

The guide plate 75 holds the moving assembly in alignment with the stationary contacts. Small pivot surfaces or ridges 83 are provided on the underside of the guide plate 75 to permit the moving contact assembly to align itself with the stationary contacts. If desired, the guide plate 75 may be omitted and the push button 53 permitted to rest directly on the bar 73 with the bar 73 disposed in the groove 77. The ridges 83 could be molded on the underside of the push button 53.

The operation of the switch shown in Figs. 3 and 4 is similar to the one shown in Figs. 1 and 2. When the push button 53 is depressed, the stress on the spring toggle members 74 is increased until the connecting bar 73 passes overcenter, thereby causing the bridging contact member 61 to be moved upwardly with a snap action. The upward movement of the bridging member is limited by the upper contacts 65 engaging the contact 56. The spring toggle members 74 are still stressed to maintain a relatively high contact pressure between the

contacts

56 and 65. When the push button 53 is released, the return spring 71 actuates the push button to its uppermost position, thereby causing the spring toggle members 74 to return the bridging contact member 61 to its lowermost position.

The switch shown in Figs. 3 and 4 is relatively simple in structure. Most of the metal parts may be stamped from sheet metal, and the insulating parts may be molded. The only dimension which must be maintained with relatively close manufacturing tolerances are the dimensions Y and Z. Furthermore, the parts may be easily assembled in the switch casing.

From the foregoing description, it is apparent that I have provided switch structures which are simple in construction and economical to manufacture and assemble. The moving contact members are actuated with a snap action at substantially the same point in the travel of the operating member. Relatively high contact pressure is obtained by maintaining the spring members of the switch under stress at all times, and the simplicity of structure i obtained by utilizing toggle-connecting levers which also function as the spring members for obtaining the snap action and/or maintaining the contact pressure. The switch may be operated manually, or it may be utilized in the automatic control of machinery and operated by parts of the machines being controlled.

Since numerous changes may be made in the above- .disposed, :pairs; of spaced stationary; contacts, a bridging toggle; members pivotallyrconnectedto the bridging contact member eandjoined together by a connecting:.bar, rsaid bar 'connecting the 'operating member .to the toggle l15 screw threaded into theend-of each block, a substantially .tween the oppositely disposed-contacts, said spring toggle ,members being stressed'when assembled inthe switch to :ibias the bridging contact :member against-cone. pair ;of

:operativelyconnected to the operating member tow-actudisposed pairs of spaced stationary; contacts,v a .bridging ment'with-said stationary contacts, a reciprocating operating member, :and a :one-piece springmember-having in- 5 *tegra lly formed generally U,-shaped toggle armspivotally .connected to the operating member to actuate the bridg- .ing contact memberybetween the oppositely disposedconagainst-one pair of stationary contacts.

- erally rectangular recess therein; generally oblong cont-act blocks disposed at the corners of said recess, ca-contact Ofthe recess and havmga s p y deposed 'rigidbridging contact member movable into'andout' of the recess and having a guide pin slidably disposed at the opposite-side of the recess, and separately mounted spring l a toggle members connecting the Operating member and the 55 e movable m onedlrectlon y an external force, and aendsof the rectangular opening in .the bridging pacontact :member, portions of said toggle members beingzdisposed at one side of the bridging contact member torpass through -actuation of the bridging contact member by:reciproca- 232333277 5 wdescribed construction {and diiiferent embodiments of and;.1the-ends ofgthe rectangular opening .in. the bridging :the; invention may-be :madewithout. ,departingtiromethe .contactimember, portions of said. toggle. membersbeing spirit 'and--sc0pet;thereof,- it is, intended that-tallzimatter -.-disposed at one sidecoftthe bridging contact member to .;co ntained in,the;foregoingdescription-r01:,showneinuthe dpasslthrough theopening in thebridging contactmember accompanying drawingshall be interpretedtas i lu trati 5 from one side V-ofzthe bridgingcontactxmember' turthe candznot-in -a-limiting.sense. other'duringactuation of the bridging.contact member by I' claim as :my invention: ,reciprocation .of the operating :member, said operating l.- lnsan electric-switch, in combination, oppositely '-member being movable in one direction by an external I force, and a return spring tormoving theoperating menicontactmemberrmovableiinto and 101111 ofabridging enher in the oppositedirection, ;gagement-.with said stationary contacts, a reciprocating 6, A l tri switch comprisinga-base having-a gener- ;operating member, ,a pair ofigenerally -U-shape1d:- p1'i g ally; rectangularrecess therein, generally oblong contact 1b1ocks, disposed *at-the corners of: said recess, acontact .::member on one side of each contact block, a terminal members to aactuatethe"bridging contact member be- "rigid bridging contact member movable into and out of bridging engagement with oppositely disposed pairs 'of said contact ;members,-said bridging contactmember having a. generally rectangular opening .thereima reciprocat- ..20 wing operating member slidably disposed at one side of the :recess and having-a guide. pin-slidably :disposed at the opposite side of the recess, separately mounted spring toggle members connecting-the operating member and .athe endsof the rectangularcopeningin the bridging, constationary contacts.

'2.:In an electric i switch, in ;combination, oppositely disposed pairs. of spaced, stationarycontacts, 2 a :bridging 'contactcmember movable into and out .of bridging engagementuwith said stationary contacts a reciprocating operating memben'anda. oneepiece spring-member .hav- 1125 ;;tact member,.portions of said toggle members being dising integrally formed generally .U-shaped :toggle arms :posed at one side of the bridging contact member to pass through the opening in the bridging contact'mernber from one -.side ofv-the bridging contact member to the other during actuationof the bridging contact member by'recip- "330 rocation of the operatingmember, said operating-member :being movable in one directionubyan-external force, and a return spring for moving the operating member in the :opposite direction, -:said return spring surrounding said guide-pin.

.7. An electric switch comprisinga base having a generally rectangular, recess therei-n general-ly oblong contact blocks ,disposedtat: the. corners of said recess, a contact :memberononeside of-each contact-bl0ck,-atterminal screw"v threaded intouthe endofeach block, a substantacts, said spring toggle arms'being-stres edzwhentassem-s40 tially rigid bridging contactdmember movable into; and 'bled in theswitch. to bias the bridging contact member bout of bridging engagement with oppositely disposed pairs of said contact members, saidflbridgingcontact member having, agenerally rectangular. opening therein,--a-reciprocating operating member slidablydisposed :at one side pivotally connected to: the:' bridging contact member and ate the bridging contact member. between the oppositely disposed contacts.

3.?In an electric switch, in combination, oppositely contact member movable into and out of bridging engageconnected to the bridging contact member and operatively 4. An electric switch comprising abase-having a genat the opposite side of the recess, separately-mounted spring toggle members connecting the operating member and the. ends of the rectangular opening in the bridging bridging engagement with oppositely disposed-pairs of Contact Portions of Said toggle-mfimbels being said contact members, said bridging contact member havp e at ne side of thebridg n Contact member? to ing a generally rectangular opening therein, a reciprocat- 61 through the p ind o membfil ing ti mb v lid bl di d one id f from one side of the bridging. contact member to the other during actuation of the bridging contact member byrecip- :rocation of the operating member, said operating member member on one side of each contact block, a terminal screw threaded into the end of each block, a substantially a returnspring for moving theoperating member in the oppositedirection,,said return spring surrounding said .guide pin andextending through the. opening in the bridging contact member.

8. An electric, switch comprising a base having a generally rectangular, recess therein, generally oblong contact blocks disposed at the corners of said recess, a contact 5 An electric switch comprising a base having a genmember 011 One Side Of each contact block, 3. terminal erally rectangular recess therein, generally oblong co Screw threaded into the end of each block, a substantially tact blocks disposed at the corners of said recess, a con- 65 rigid bridging Contact member le into and out of tact member on one side of each contact block, a termibridging engagement With pp y disposed Pairs of nal screw threaded into the end of each block, a substan- Said C a members, Said bridging Contact member 115W- tially rigid bridging contact member movable into and g a g y rectangular p g thfil'fiin, a reciprocatout of bridging engagement with oppositely disposed ing operating member slidably disposed at one side of pairs of said contact members, said bridging contact the recess and having a guide pin slidably disposed at member having a generally rectangular opening therein, a the opposite side of the recess, separately mounted spring reciprocating operating member slidably disposed at one toggle members connecting the operating member and side of the recess and having a guide pin slidably disposed the ends of the rectangular opening in the bridging contact at the opposite side of the recess, separately mounted member, portions of said toggle members being disposed spring toggle members connecting the operating member atone side of the bridging contact member to pass through the opening in the bridging contact member from one side of the bridging contact memberto the other during 60 tion of the operating member.

the opening in the bridging contact member from one side of the bridging contact member to the other during actuation of the bridging contact member by reciprocation of the operating member, said operating member being movable in one direction by an external force, and a return spring for moving the operating member in the opposite direction, said return spring surrounding said guide pin and having one end engaging said base below the bridging contact member and the other end engaging the operating member above the bridging contact member.

9. An electric switch comprising a base having a generally rectangular recess therein, generally oblong contact blocks disposed at the corners of said recess, a contact member on one side of each contact block, a terminal screw threaded into the end of each block, a substantially rigid bridging contact member movable into and out of bridging engagement with oppositely disposed pairs of said contact members, said bridging contact member having a generally rectangular opening therein, a reciprocating operating member slidably disposed at one side of the recess and having a guide pin slidably disposed at the opposite side of the recess, toggle levers engaging the ends of the rectangular opening in the bridging contact member, and spring arms connecting the toggle levers and the operating member, portions of said toggle levers being disposed at one side of the bridging contact member to pass through the opening in the bridging contact member from one side of the bridging contact member to the other during actuation of the bridging contact member by reciprocation of the operating member.

10. An electric switch comprising a base having a recess therein, spaced stationary contacts disposed in said recess, a substantially rigid bridging contact member movable into and out of bridging engagement with said stationary contacts, said bridging contact member having a generally rectangular opening therein, a reciprocating operating member slidably disposed at one side of the recess, a guide pin for the operating member engaging the opposite side of said recess, and spring toggle members connecting the ends of the rectangular opening in the bridging contact member and the operating member, portions of said toggle members being disposed at one side of the bridging contact member to pass through the opening in the bridging contact member from one side of the bridging contact member to the other during actuation of the bridging contact member by reciprocation of the operating member.

11. An electric switch comprising a base having a recess therein, spaced stationary contacts disposed in said recess, a substantially rigid bridging contact member movable into and out of bridging engagement with said stationary contacts, said bridging contact member having a generally rectangular opening therein, a reciprocating operating member slidably disposed at one side of the recess, a guide pin for the operating member disposed in said recess, spring toggle members connecting the ends of the rectangular opening in the bridging contact member and the operating member, portions of said toggle members being disposed at one side of the bridging contact member to pass through the opening in the bridging contact member from one side of the bridging contact member to the other during actuation of the bridging 7 contact member by reciprocation of the operating memher, said operating member being movable in one direction by an external force, and a return spring for moving the operating member in the opposite direction, said return spring surrounding said guide pin.

12. An electric switch comprising a base having a recess therein, spaced stationary contacts disposed in said recess, a substantially rigid bridging contact member movable into and out of bridging engagement with said stationary contacts, said bridging contact member having a generally rectangular opening therein, a reciprocating operating member slidably disposed at one side of the recess, a guide pin for the operating member engaging the opposite side of said recess, a spring-seating member movable with said operating member, said spring-seating member having an opening therein for said guide pin and oppositely disposed spring seats thereon, and spring toggle members connecting the ends of the rectangular opening in the bridging contact member and the spring seats on said spring-seating member, portions of said toggle members being disposed at one side of the bridging contact member to pass through the opening in the bridging contact member from one side of the bridging contact member to the other during actuation of the bridging contact member by reciprocation of the operating member.

13. An electric switch comprising a base having a recess therein, spaced stationary contacts disposed in said recess, a substantially rigid bridging contact member movable into and out of bridging engagement with said stationary contacts, said bridging contact member having a generally rectangular opening therein, a reciprocating operating member slidably disposed at one side of the recess, a guide pin for the operating member disposed in said recess, a spring-seating member movable with said operating member, said spring-seating member having an opening therein for said guide pin and oppositely disposed spring seats thereon, spring toggle members connecting the ends of the rectangular opening in the bridging contact member and the spring seats on said springseating member, portions of said toggle members being disposed at one side of the bridging contact member to pass through the opening in the bridging contact member from one side of the bridging contact member to the other during actuation of the bridging contact member by reciprocation of the operating member, said operating member being movable in one direction by an external force, and a return spring for moving the operating member in the opposite direction, said return spring surrounding said guide pin.

References Cited in the file of this patent UNITED STATES PATENTS 2,125,432 Du Brie Aug. 2, 1938 2,332,911 Hausler Oct. 26, 1943 2,412,119 Bentley Dec. 3, 1946 2,476,056 Martin July 12, 1949 2,519,297 Stump et a1. Aug. 15, 1950 2,608,628 Dietrich Aug. 26, 1952 FOREIGN PATENTS 546,135 Great Britain June 29, 1942