US2748214A - Switch - Google Patents

Description

May 29, 1956 R. B. lMMEL 2,748,214

SWITCH Filed April 21, 1951 2 Sheets-Sheet l Fig.|.

WITNESSES: INVENTOR Ralph B.I'mmel.

"* W y ow R. B. lMMEL May 29, 1956 SWITCH 2 Sheets-Sheet 2 Filed April 21, 1951 i O m m mm mm M w 2 2 Q O m B m m 7 I I m .@-8 M 4 SZm MBw 28 :3.

INVENTOR Ralph B.Imme|. @gfi/M X ATTORN WITNESSES ljnited States Patent SWITCH Ralph B. Immel, Williamsville, N. Y., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application April 21, 1951, Serial No. 222,203

7 Claims. (Cl. 200-67) This invention relates generally to electric switches, and more particularly to such switches which operate with a snap action.

There are many applications in industry for a small precision type of snap switch which will positively operate with a snap action, and which will reliably operate at precisely the same point in the path of travel of the switch operating member repeatedly.

Accordingly, one object of this invention is to provide a novel form of snap-acting switch which is economical to manufacture and yet is reliable in operation.

A more specific object of this invention is to provide a novel form of snap action switch having a movable contact member which is relatively light in weight, yet is substantially rigid and having good current carrying ability.

Another object of this invention is to provide a snap acting switch having a novel form of snap acting mechanism including an operating spring and relatively rigid toggle-like members connecting the handle to the movable contact of the switch.

Still another object of this invention is to provide a. novel form of push button operated snap action switch.

These and other objects of this invention will become more apparent upon consideration of the following detailed description of preferred embodiments thereof, when taken in connection with the attached drawings in which:

Figure 1 is a top view of a switch constructed in accordance with this invention;

F ig. 2 is a side view taken at the open side of the switch casing with the cover removed, and showing the bridging contact at its lower closed circuit position;

Fig. 3 is a view similar to Fig. 2, but showing the bridg-' ing contact at its upper closed circuit position;

Fig. 4 is an exploded view of certain parts of the switch, with such parts being shown in perspective;

Fig. 5 is a view similar to Figs. 2 and 3 but illustrating a modified form of switch;

Fig. 6 is an exploded view of certain parts of the switch operating mechanism shown in Fig. 5, with the parts there of shown in perspective;

Fig. 7 is a view similar to Figs. 2, 3 and 5 but illustrating a still further modified form of switch, and

Fig. 8 is an exploded view of certain parts of the switch mechanism illustrated in Fig. 7, with the parts thereof being shown in perspective.

Referring to the form of switch shown in Figs. 1-4, there is provided a base or open sided casing 2 of insulating material, preferably a molded insulating material, with a cover 4 for the open side of casing 2 adapted to be secured thereto by any desired securing means such as bolts or rivets passing through the holes 6 in the casing and corresponding holes in the cover.

Mounted in casing 2 through the open side thereof are upper and lower pairs of contact blocks 8 constructed of an electrical conducting material, which may be steel which is covered by a corrosion resistant good electrical conducting material, as by being silver plated; Although two pairs of such contact blocks are illustrated in Figs. 2 and 3, it will be understood as the description proceeds that either the upper pair or the lower pair may be omitted where but a single circuit is to be controlled by the switch. Each contact block 8 has an inwardly extending integral supporting rod 10 which is adapted to be received in a correspondingly shaped opening in casing 2, and each contact block has a contact 12 mounted thereon facing either upwardly or downwardly depending upon whether the particular contact block 8 forms one of the pair of upper terminals or one of the pair of lower terminals. The contacts 12 are preferably formed of some good electric conducting material such as silver or an alloy thereof. Each contact block 8 further has the corners thereof cut away at the outer end of the block to form shoulders 14 which are adapted to be engaged by cover 4 when it is secured in place on the casing to thereby hold the contact blocks in the casing. Furthermore, the outer end of each terminal block 8 is provided with a threaded opening 16, for receiving a threaded terminal screw 18.

A bridging contact 20 is adapated to be located between the upper and lower pair of contact blocks and contacts 12 thereof, with this bridging contact preferably being formed of a thin sheet of a resilient conducting material, for example, a copper alloy such as beryllium copper. While such a material is flexible and resilient the bridging contact is, for the most part, made relatively rigid by having at each side thereof down turned stiffening flanges 22 which are integral with the material of the bridging contact. Bridging contact 20 being made of relatively thin material is thereby light in weight, and yet the flanges 22 make it relatively rigid, to thereby reduce any sliding and wiping action of the contacts 24 on the bridging mem: her with respect to stationary contacts 12, because for optimum life of silver or silver alloy contacts it is essential to reduce all contact sliding and wiping action to a minimum. Another advantage obtained from using a light weight bridging contact member is that the operation diiferential in its movement from one position to another is reduced to a minimum. In other words, it is capable of extremely fast movement, having a low inertia, and consequently can be operated with an extremely fast snap action.

The contacts 24 rigidly secured on bridging contact 20 are preferably of the same material as stationary contacts 12, and the bridging contact 20 is provided with a central opening 26 for a purpose to be described, and substantially rectangular openings 28 and 30 at each end, also for a purpose to be described.

The switch operating member is illustrated as being a push button 32 formed of insulating material, preferably a molded insulating material, and being rectangular insection so as to be received in a notch 36 in the top of casing 2 to be guided for rectilinear movement therein. Push button 32 has an inner stop flange 34 which is adapted to engage stop shoulders 33 formed integral with casing 2 to limit outward movement of the push button. At its inner end push button 32 is provided with a guide pin 40, illustrated as being rectangular in cross section, and adapted to be received in a similarly shaped opening in the bottom of casing 2 for the purpose of assisting in guiding the rectilinear movement of push button 32. A coil compression return spring 42 is provided about guide rod 40, with both adapted to extend freely through central opening 26 of the bridging contact 20, and with return spring 42 reacting between the base of casing 2 and an operating spring 44,

holding the latter in engagement with the inner end of push button 32, and thereby biasing the push button 32 to its outermost position as defined by stop flange 34 and stop shoulders 38.

The operating spring 44 is a leaf type of spring having an intermediate apertured portion for receiving the guide pin 40 of push button 32, and in turn being received in a groove 46 provided at the inner end of push button 32 shaped to correspond with the shape of the intermediate portion of operating spring 44. At each end operating spring 44 is provided with downwardly extending legs 50 with each having at the inner side thereof a transversely extending pivot recess 48. Toggle links 52 are provided for operatively connecting the operating spring 44 with bridging contact 26. Each of these toggle links 52 is formed with an outer reduced end 54 adapted to be received in one of the pivot recesses 48 of operating spring 44 to be pivotally engaged there-. in, and each toggle link 52 further is provided with in-. tegral side flanges so that the links are relatively rigid, with these side flanges 56 having at the other end of each toggle link notches 58 formed therein for pivotally receiving the edges 59 or 6 1 of the openings 28 and 30 cut into bridging contact 20.

The distance between pivot recesses 48 of operating spring 44 is made to be less than the sum of twice the length of a toggle lever 52 and the width of the transverse onn Pa f br d ng cont t 2 having the p o edges 59 and A r i sly, i w l be appar h h p t n spr 44 a s mb e th push button 32 and toggle levers 52 connecting it; with bridging contact 20 in switch casing 2, that the operating spring will be stressed, and consequently the moving contact assembly will always be in unstable mechanical equilibrium except at the closed circuit positions shown in Figs. 2 and 3, respectively. In Fig. 2 the stress in operating spring 44 causes push button 32 to be projected upwardly until its stop flange 34 engages the stop shoulders 38, While at the same time it forces bridging contact 20 to a lower position where its contacts 24 engage the lower pair of fixed contacts 12 under predetermined contact pressure. pressed from the position shown in Fig. '2 the operating spring 44 will be moved downwardly and will be further stressed due to the outward movement of the outer ends of toggle levers 52 until the pivot recesses 48 go past a center line extending between pivot notches 58 and the point of engagement of contacts. 24 with the lower pair of contacts 12, whereupon the bridging contact 20 will move to the position shown in Fig. 2 with a rapid snap action. It will be observed that during this operation the outer ends of operating spring 44 and of toggle levers 52 have passed through the openings 28 and 30 in bridging contact 20. When the push button 32 is released, return spring 42 will return it'to its original position thus moving operating spring 44 and toggle levers 52 back over center to the position shown in Fig. 2, which will cause the bridging contact 20 to move into engagernent with the lower pair of stationary contacts 12 with a rapid snap action.

It will be observed that the moving parts of this switch are held in assembled relation by return spring 42 which holds the operating spring 44 in engagement with the inner end of push button 32 when cover 4 issecured to casing 2. While this particular design of switch is relatively simple, it can nevertheless perform a precision type of operation, the only critical dimensions being-the When push button 32 is de-v width of the central transverse part of bridging contact 20 carrying pivot edges 59 and 61, the lengths oftoggle levers 52, and the distance between pivot recesses- 48 of operating spring 44. Moreover, all parts of the snap acting mechanism are relatively rigid except for operating spring 44, although there will be some resiliencypresent in bridging contact 20, particularly in the outer end connecting parts thereof, so that contacts 24 may have some flexibility of their mounting.

Referring now to the modification shown in Figs. 5 and 6, it is similar to the design illustrated in Figs, 1 to 4 in that it is provided with an open, sided, baseor casing 60 formed of a material similar to that of easing 2, and is adapted to have the open side of casing 60 closed by a cover (not shown) which may be secured in position by bolts or rivets extending through openings 62 in the casing 60. Instead of having the switch terminals accessible at the open side of the casing, these are mounted in the base of the casing in the form of a switch shown in Fig. 5, there being one pair of terminals 64 at the extreme outer ends secured in suitable openings in the base of casing 60 and having secured to their inner ends U-shapcd terminal straps 66 which carry downwardly facing upper stationary contacts 68, of a material similar to the contacts 12 referred to previously. An inner pair of terminals 70 are secured in suitable openings in the bottom wall of casing 60, and have terminal straps 72 carrying at their outer ends upwardly facing relatively stationary contact 74 disposed in opposed relation, respectively, to stationary contacts 68.

The bridging contact 76 employed in this form of switch is preferably made of the same relatively thin material as bridging contact 20 shown in Figs. 1 to 4, and has a central opening 78 for a purpose to be described, and is formed with a pair of substantially U- shaped slots 80 at each end to form a pair of oppositely extending leaf spring members 82 integral with bridging contact 76 with these members actually comprising resilient toggle members formed integral with the central part of bridging contact 76. Each of the toggle members 82 is provided at its outer end with a projec tion 84. of reduced width, for a purpose to be described, and the bridging contact 76 further has slide stiffening flanges 86, and contacts 88 secured at each end thereof.

An operating spring 80 of the leaf type is provided with a central opening 92 for receiving a guide pin 94 secured to the inner end of a push button 96, which may be formed, of a material similar to that of the push button 32 shown in Figs. 1 to 4. Push button 96 is further formed with a groove 98 at its inner end in which operating spring is. received at a point intermediate its length, with opposite ends of operating spring 90 being downwardly inclined and bent to form notches 102 a their outer ends, with an opening 104 located centrally at the base of each notch.

In assembling the parts, bridging contact 76 and operating spring 90 are assembled together by bending the resilient toggle members 32 upwardly to fit the outer ends thereof in the notches 102 of operating spring 90 with the projections 84 on the resilient toggle members being located in openings 104. It is necessary to bend the rcsilienttoggle members 82 upwardly because the distance between notches 102 in operating spring' ti is less than the distance between the outer ends of resilient toggle members 82. This subassembly of operating spring 98 and. bridging contact 76 may then be mounted in casing 60 through the open side thereof with a coil compression return spring 109 receiving guide rod 94 of the push button 96, and both extending through the opening 78 in the bridging contact. Return spring 10! engages between the lower side of operating spring 90 and the bottom wall of casing 60. With push button 96 in the position shown in Fig. 5, it will be observed that return spring holds operating spring 90 in engagement with the slot 98 in the inner end' of push button 96, and the whole assembly is guided by the rectanguiar slot provided. in. the casing for push button 96 at its upper end, and by the guide pin 94 which is received in an opening provided in the'bottom of casing 60-.

In Fig; 5, pushbutton 96' is' held at its uppermost position by return spring 104), and the operating spring 90 and resilient toggle members 82 are stressed to provide engagement of bridging contacts 88 with the lower pair of stationary contacts 74 under predetermined contactpressure. When pushbutton 9,6 is depressed, operating spring 9,0,willbe further stressed andmove downwardly until the notches 102, in which the outer ends of resilient toggle members 82 have pivotal movement, are moved below a line connecting a central point of bridging contact 76 and the point of engagement of contacts 88 and 74, to a lower overcenter position, when bridging contact 76 will be rapidly moved with a snap action to an upper closed circuit position wherein its contacts 88 are engaged with the upper pair of stationary contacts 68. Upon release of push button 96, return spring 100 will move the push button and operating spring 90 upwardly over the center line previously mentioned, and bridging contact 76 will then return to its lower closed circuit position shown in Fig. with a snap action.

This particular form of switch assembly is somewhat simpler than that illustrated in Figs. 1 to 4 and can be made to operate in a precise manner with the only dimensions which need be made to close tolerances being the distance between pivot notches 102 of the operating spring, and the distance between the outer ends of resilient toggle members 82. Both this form of switch and that illustrated in Figs. 1 to 4 have the further advantage that the pivot points of the operating spring and toggle members are spaced a considerable distance apart so that there is little tendency for the bridging contact to rotate relative to the operating spring, thus preventing side thrust and friction between the push button and its guide surfaces formed in the switch casing.

Referring now to the form of this invention shown in Figs. 7 and 8, the casing is substantially identical with that shown in Figs. 1 to 3, as Well as the stationary contacts and their mode of mounting in the casing, so that like reference numerals have been applied to these parts and a detailed description thereof will not be repeated. The bridging contact 106 employed in this embodiment of this invention is formed of a light thin resilient conducting material as in the case of the bridging contacts 20 and 76 previously described, and has a single longitudinally extending rectangular opening 108 formed therein. Bridging contact 106 is formed, in effect, with a double channel section to supply the desired rigidity thereof. Thus, in addition to having side stiffening flanges 110, it has additional flanges 112 extending longitudinally along opposite inner sides of the opening 108. The double flanges act to increase the current carrying and thermal capacity of bridging contact 106, with the current carrying capacity being almost equal to that of the bridging contact before it is blanked out. As a matter of fact, only a narrow rectangular strip of material is blanked out in forming bridging contact 106 so that it actually has almost twice the cross sectional area for current carrying compared to that of the bridging contacts 20 and 76 previously described. Bridging contact 106 has secured thereto at each end, contacts 114 at the top and bottom sides thereof.

A push button operating member 116 is provided for the switch shown in Figs. 7 and 8, and may be formed of an insulating material as in the case of push buttons 32 and 96 previously described. Push button 116 has an inner stop flange 118 for limiting its outward movement in casing 2, and is formed with groove 120 at its inner end for receiving the intermediate part of a generally U-shaped operating spring 122, which has an opening 124 for receiving the guide pin 126 secured to the inner end of push button 116. The outer ends of the arms of operating spring 122 at their outer sides are formed with pivot grooves 128 for receiving the inner ends of'toggle levers 130. Each of toggle levers 130 is formed with opposite side flanges 132 to make these levers substantially rigid, with these flanges at the outer end of each toggle member being formed Withpivot notches 136 to receive one of the transverse edges at the outer ends'of opening 108 in the bridging'contact. Moreover, at the inner end of each toggle lever 130 the side flanges 132 are extended to lie on opposite sides of the arm of operating spring 122 which it engages.

When the parts are assembled in the manner shown in Fig. 7, operating spring 122 is under stress because the distance between its pivot recesses 128 is made to be greater than the distance between the inner pivot edges of toggle levers when they are pivotally assembled with bridging contact 106. Consequently, the operating spring will, in the position of the parts shown in Fig. 7 urge push button 116 to its outermost position where its stop flange 118 engages stop shoulders 38 formed in casing 2, and will bias bridging contact 106 downwardly to cause engagement of its contacts 114 with the lower pair of stationary contacts 12 under predetermined pressure. When push button 116 is depressed the operat ing spring 122 will be stressed until it moves over center which will occur substantially at the point where toggle levers 130 become aligned in opening 108, whereupon bridging contact 106 will move upwardly with a rapid snap action. As in the case of the embodiments of this invention previously described, when push button 116 is released, return spring 42 will return push button 116 and operating spring 122 to their upper position, wherein the spring again passes overcenter and operates the bridging contact to its lower closed circuit position shown in Fig. 7 with a rapid snap action.

The number of parts employed in this design is the same as are employed in the design shown in Figs. 1 to 4, and again the design is relatively simple and can be made to operate in a precise manner, with the only critical dimensions being the length of opening 108, the lengths of toggle levers 130, and the distance between pivot grooves 128 in operating spring 122.

In each of the embodiments of this invention which have been described there is provided a switch which is of relatively simple and economical construction adapted to be operated by an operating member in a manner to open and close the circuit with a snap action. This is accomplished in eachcase by the provision of an operating spring actuated by the operating member to go overcenter relative to pivot points located on a bridging contact member, and since all of the moving parts are made of relatively light construction an extremely rapid snap action movement is obtained as well as a precision type of operation, with respect to repeated operations occurring at the same point in the path of travel of the operating member is concerned.

Having described preferred embodiments of this invention in accordance with the patent statutes, it is desired to point out that the invention is not limited to the precise forms and constructions specifically disclosed herein inasmuch as it will be apparent to persons skilled in the art that various changes and modifications may be made therein without departing from the broad spirit and scope of this invention. Accordingly, it is desired that this invention be not restricted to the precise constructions herein disclosed, but that it be interpreted as broadly as possible and that it be limited only as required by the prior art.

I claim as my invention:

1. A switch comprising, a casing of insulating material, spaced contacts stationarily mounted in said casing, a bridging contact member mounted in said casing for movement toward and away from opposite sides of the easing into and out of engagement with said spaced contacts, said bridging contact member having a central opening therethrough, a push button operating member extending through an opening in one of said opposite sides of the casing and having stop means limiting its outward movement, operating spring means seated in a groove in the inner end of said push button and having spaced ends disposed externally of the push button, said spring means being held in stressed condition by toggle means interposed between the spaced ends of said spring means and said bridging contact member for operating said bridging contact member with a snap action, and return spring means acting directly between said push button and the other of said opposite walls of the casing to normally maintain said push button at extended position relative to said casing and said movable bridging contact member at one of its positions, said return spring means extending from the side of the casing opposite the push button through the opening in the bridging contact member and between the spaced ends of the spring means to the push button.

2. A switch comprising, a base of insulating material, spaced contacts stationarily mounted on said base, a bridging contact member mounted for movement on said base into and out of engagement with said spaced contacts, a push button operating member movably mounted on said base and having stop means limiting its outward movement, operating spring means abutting the inner end of said push button and having spaced ends disposed externally of the push button, said spring means being held in stressed condition by togglemeans interposed between said spring means and said bridging member for operating said bridging member with a snap action, and return spring means acting directly between said push button and said base to normally maintain said push button at extended position relative to said base and said movable bridging member at one of its positions, said return spring means extending from said base through the opening in the bridging member and between the spaced ends of the spring means to the push button.

3. A switch comprising, a base of insulating material, generally rectangular contact blocks stationarily mounted in the base in spaced relation, each contact block having a contact on one side and an opening in one end for receiving a terminal screw, said opening extending longitudinally of the contact block, said contact blocks being interchangeable in the base, a bridging contact member mounted for movement into and out of engagement with said spaced contacts, said bridging member having a central opening therethrough, an operating member mounted in said base for movement in substantially the same direction as said bridging contact member, operating spring means disposed in said operating member with spaced portions extending externally of the operating member, a pair of toggle levers pivotally engaging the bridging member and the spaced portions of the operating spring means to operate said bridging member to open and closed circuit positions with a snap action in response to movement of said operating member in opposite directions, and a coil spring for normally maintain ing the operating member at extended position relative to the base and the bridging contact member in engagement with part of said stationary contacts, said coil spring having one end engaging the base opposite the operating member and the other and acting on the operating member, said coil spring extending through said opening in the bridging contact member and between the spaced portions of said operating spring means.

4. A switch comprising, a base of insulating material. generally rectangular contact blocks stationarily mounted in the base in spaced relation, each contact block having a contact on one side and an opening in one end for receiving a terminal screw, said opening extending longitudinally of the block, said contact blocks being interchangeable in the base, a bridging contact member mounted for movement into and out of engagement with said spaced contacts, said bridging contact member having a longitudinally extending opening therein forming bearing parts at opposite ends of the opening, an operating member mounted in said base for movement in substantially the same direction as said bridging member, operating spring means disposed in said operating member with spaced portions extending toward said bridging member and having bearing parts adjacent their outer ends, a pair of toggle levers pivotally engaging the bearing parts of said bridging member and said spring means to operate said bridging member to open and closed circuit positions with a snap action in response to movement of said operating member in opposite directions, and a coil spring for normally maintaining the operating member at extended position relative to the base and the bridging member in engagement with part of said stationary contacts, said coil spring having one end engaging the base opposite the operating member and the other end acting on the operating member, said coil spring extending through said opening in the bridging contact member and between the spaced portions of said operating spring means.

5. A switch comprising, a base of insulating material, generally rectangular contact blocks stationarily mounted in the base in spaced relation, each contact block having a contact on one side and an opening in one end for receiving a terminal screw, said opening extending longitudinally of the contact block, said contact blocks being interchangeable in the base, a removable cover for retaining the contact blocks in the base, a generally rectangular bridging contact member mounted for movement into and out of engagement with said spaced contacts, said bridging contact member having a longitudinally extending opening therein forming bearing parts at opposite ends of the opening, an operating member mounted in said base for movement in substantially the same direction as said bridging member, operating spring means disposed in said operating member with spaced portions extending toward said bridging member and having bearing parts adjacent their outer ends, a pair of toggle levers pivotally engaging the bearing parts of said bridging member and said spring means to operate said bridging member to open and closed circuit positions with a snap action in response to movement of said operating member in opposite directions, and a coil spring for normally maintaining the operating member at extended position relative to the base and the bridging member in engagement with part of said stationary contacts, said coil spring having one end engaging the base opposite the operating member and the other end acting on the operating member, said coil spring extending through said opening in the bridging contact member and between the spaced portions of said operating spring means.

6. A switch comprising, a base of insulating material, spaced contacts stationarily mounted in the base, a generally rectangular bridging contact member mounted for movement into and out of engagement with said spaced contacts, said bridging contact member having a longitudinally extending opening therein forming bearing parts at opposite ends of the opening, an operating member mounted in said base for movement in substantially the same direction as said bridging member, operating spring means disposed in said operating member with spaced portions extending toward said bridging member and having bearing parts adjacent their outer ends, a pair of rigid toggle levers pivotally engaging the bearing parts of said bridging member and said spring means, said toggle levers being supported only at their pivot points to operate said bridging member to open and closed circuit positions with a snap action in response to movement of said operating member in opposite directions, and a coil spring for normally maintaining the operating member at extended position relative to the base and the bridging member in engagement with part of said stationary contacts, said coil spring having one end engaging the base opposite the operating member and the other end acting on the operating member, said coil spring extending through said opening in the bridging contact member and between the spaced portions of said operating spring means.

7. A switch comprising, a base of insulating material, spaced contacts stationarily mounted in the base, an elongated bridging contact member mounted for movement into and out of engagement with said spaced contacts, said bridging contact member having at least one open ing therein, an operating member mounted in said base for movement in substantially the same direction as said bridging member, operating spring means disposed in said operating member with spaced portions extending toward said bridging member and having bearing parts adjacent their outer ends, a pair of rigid toggle levers having ends pivotally engaging the bridging member and the bearing parts of the operating spring means, ends of said toggle levers passing through an opening in the bridging member to operate said bridging member to open and closed circuit positions with a snap action in response to movement of said operating member in opposite directions, and a coil spring for normally maintaining the operating member at extended position relative to the base and the bridging member in engagement with part of said stationary contacts, said coil spring having one end engaging the base opposite the operating member and the other end acting on the operating member, said coil spring extending through an opening in the bridging contact member and between the spaced portions of said operating spring means.

References Cited in the file of this patent

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