US1925612A - Snap switch - Google Patents

Description

J. C. SNELL Sept. A5, 1933.

SNAP SWITCH Filed July 25, 1927 a H m M mi 2 M 3 3 Ww 9 ln@ nd L y C va M y?. /Aun? d I. ad ...E

ATTORNEY.

Patented Sept. 5, 1933 UNITED STATES PATENT OFFICE Clum Manufacturing Company,

Milwaukee,

Wis., a corporation of Wisconsin Application July 25, 1927. Serial No. 208,115

25 Claims.

This invention relates to improvements in snap switches.

It is the primary object of the invention to provide a novel and improved construction of snap switch which will be free of spring breakage while possessing the desirable characteristics of quick, positive operation, wiping contact and simplicity.

In the drawing:

Figure 1 is a vertical central section through a double throw snap switch embodying the invention.

Figure 2 is a plan view of the switch mechanism shown in Figure 1, the actuating lever being broken away and the switch casing cover removed to expose the contacts.

Figure 3 is a transverse vertical section through the switch device shown in Figures 1 and 2.

Figures 4 and 5 are detailed views showing 20 fragmentary sections in the plane of Figure l, and illustrating successive positions of the parts during switch operation.

Like parts are identified by the same reference characters throughout the several views.

The switch casing may be of any desired construction. In the present device the casing comprises a stamping of generally rectangular outline forming a box open at its top and provided at its upper margin with outstanding anges 11. The casing cover 12 has depending flanges 13 at its sides which t over anges 11 of the casing. Portions of the flanges 13 comprise tongues which are folded inwardly at 14 (see Figure 3) to engage about anges 11 of the casing and thereby to secure the cover in place thereon. A central opening 15 in the cover receives the switch lever which is fulcrumed upon a bearing pin 21 extending transversely through the aperture 22 of the switch case and conned at its ends through the flanges 13 of the cover. The switch cover 12 may be provided if desired with mounting screws at 23.

The switch mechanism will now be described. In this particular device the switch mechanism is duplex and in reality involves two separate switches controlled by thesame lever. It,l will be obvious, however, that either switch may be used independently if desired.

Terminal contacts 25 are preferably designed in the form of tubular rivets. The bottom wall 26 of the switch case is apertured at 27 to receive the dielectric bushings 28. Sheets of dielectric material at 29 and 30 are provided with registering openings through which the reduced portions 31 of the contact rivets pass. Each rivet is shouldered as indicated for engagement with the upper dielectric sheet 29 and each rivet is upset upon a Washer 32 engaged with the lower sheet of dielectric 30. Thus the contacts themselves are arranged to anchor the dielectric ma- 69 terial whereby each contact is insulated from the switch casing. Each tubular rivet 25 is preferably tapped internally to receive a suitable terminal screw 33.

Centrally disposed intermediate the contacts 25 65 and in the plane of the bearing pin 21 is a connector or stop block 35 of rectangular outline with plane opposed surfaces 36. This block, like contacts 25, comprises the head of a tubular rivet, reduced portion 31 of which extends through the 70 opening 27 in the bottom of the switch casing and is suitably insulated from the switch casing by a bushing 28 and the dielectric sheets 29 and 30 as previously described. In addition to washer 32, however, connector device 35 is preferably pro- 75 vided with a washer 37 disposed upon the dielectric strip 29 and providing a seat for the spring contacts 40.

Each of the contacts is preferably formed to the shape indicated from a flat strip of spring 8 material such as spring bronze or the like. Each contact includes a relatively straight leg portion 41 normally in faced contact with the flat surface 36 of the central connector block 35. Each contact leg 37 rises vertically above block 35 in operative proximity to the lower extremity of actuating lever 20, and is thence curved outwardly and downwardly in a broad bend at 38 which merges into the arm 39 leaning to the substantially at contact surface at 42. In the normally open position of the switch each of the contact surfaces 42 is spaced from the upper endof its corresponding contact head 25, the planes of the contact surfaces being convergent toward the central block 35.

The contact devices 40 are not only resilient in themselves but they are also resiliently supported by means of the helical compression springs 43 and a oating spring guide 44 which is reciprocable freely to a transverse aperture 45 in the central contact block 35 and is headed at its ends at 46 to retain the springs 43. Each spring is provided with an aperture registering with hole 45 through the central block 35 and loosely receiving the spring guide 44. The lower end of each of the spring contact -devices 40 is square cut and rides upon the washer 37. No other means is provided for guiding the spring contact devices or fixing their normal positions. The helical compression springs 43 are constantly acting against 11 the relatively straight leg portions 41 of the spring contacts to maintain such contacts in the positions in which they appear in full lines in Figure 1.

The lower extremity 48 of the hand lever 20 fits rather closely between the upper portions of spring legs 41 and is also closely adjacent to the curvilinear spring portions 38. It will be obvious that whenever the lever 20 is oscillated about its fulcrum pin 21 its extremity 48 will engage one of the spring contact legs 41 in a direction tending to thrust the contact out of engagement with block 35.

The resistance or compression of each spring 43 is preferably lower than the resistance to exion of the contact spring 40. As a result the effect of the initial movement of actuating lever 20 will be to displace contact spring 40 bodily to the position in which such spring is illustrated in Figure 4. It will be noted that the spring has oscillated bodily away from block 25, pivoting about its point of engagement in the angle between such block and the washer 37. In the course of this pivotal movement of the contact spring 40 one or both of the compression springs 43 has been compressed, the spring guide 44 being axially movable to allow the displacement to occur in both springs. It will be noted furthermore that the angle of contact surface 42 on the moving contact devices 40 is so chosen with reference to the plane of the upper face of xed contact head 25 that the surface 42 will lie flat upon contact head 25 as a result of the initial movement of the lever.

During the continued movement of lever 2O toward one of its dotted line positions in Figure 1 the rounded corners of the extremity 48 of such lever will be caused to ride upon the arcuately bowed portions 38 of the contact with which the lever is engaged. It will be obvious that if the surface 42 has contact with the upper surface of head 25 no further bodily pivotal movement of the spring contact device 40 can occur. Consequently, in the final movement of the actuating lever7 the device 40 is caused to ex throughout its curved portion 38, the pressure tending to flatten the curve as a result of the continued movement of the lever. The parts ultimately reach the position in which they are illustrated in Figure 5.

As a result of the flattening of the curvature of the bowed portion 38 of the contact device, such device has been caused to increase to some extent its length as measured from the end of surface 42 to the fulcrum point at the lower end of leg 41. This increase in the overall length of the device results in a sliding movement of contact surface 42 across the top of contact head 25. This produces the desired wiping contact which keeps the contact surfaces free of corrosion and insures a good electrical connection through the switch.

It will further be noted that when the actuating lever reaches its ultimate position as shown in full lines in Figure 5 and in dotted lines in Figure l the under surface of extremity 48 of the lever will be approximately tangential to vthe curve of the bowed portion 38 of contact device 40. Furthermore, the resilient thrust exerted by the compressed contact device and springs 43 will be substantially along the radius of the lever which intersects the point of tangent. The movement of the lever beyond this position is preferably restricted by engagement of the lever with the extremities of the opening 15 in which it moves. Accordingly the parts will readily remain balanced in the Figure 5 position for as long a time as may be desired.

When the switch is to be opened lever 20 will be moved toward is central position in which it is shown in full lines in Figure l. As soon as the center line of the lever no longer corresponds with the line of thrust exerted through the contact device, a condition of unbalance will be found to exist in which the lever will be actuated with considerable force toward its off position. Obviously the contactbetween parts 40 and 25 will not be broken as long as part 40 is subject to distortion. In other words the contact will be maintained until the switch lever reaches its Figure 4 position at which time the pressure tending to restore it to its central or off position is at a maximum. At this time also the lever will normally have reached a relatively rapid rate of oscillation. Consequently the final break or opening movement of the switch will be rapid and decisive and will produce a-minimum pitting of the contact surfaces.

It is found that the design of switch herein disclosed operates very effectively to break any arc which tends to be formed upon the separation of the contacts, as when the switch lever is returned to its central position. This result is achieved due to the engagement of the moving contact with the positive stop which, in the case of the present device, is furnished by the mounting block 35. As a result of the sudden engagement of the moving contact with this block, it is found that the resiliently supported free end of the contact arm whips outwardly beyond its normal open position thereby achieving momentarily a much greater separation than would be the case but for the effect of momentum following the i sudden cessation of the bodily movement of the arm. The greater separation thus achieved readily destroys any arc which may tend to be formed under normal operating circumstances.

It will be observed that the construction hercin disclosed is particularly adapted for use in connection with a double throw switch as illustrated. The organization of the actuating lever with the contact device 40 is such as to lend itself to a duplex switch mechanism. As above indicated, however, either switch may bel used singly if desired.

Due to the peculiar formation and mounting of the spring contact device 40 `it will be apparent that a relatively great wiping movement and a relatively decisive snap action may be accomplished with comparatively slight distortion of the contact spring. Experiments with the device have demonstrated an exceptional freedom from spring crystallization or breakage and an equally exceptional freedom from pitting or corrosion of the contact surface.

I attribute the freedom from breakage to the fact that there is no sharply dened point at which exion or distortion of the spring contact 40 occurs. The contact device is not anchored anywhere and is free to move at all times and at all points under the pressure to which it is subject. If it were riveted or otherwise made fast to block 35 it would tend to bend Linder pressure of lever 20 at the point of leaving such block. Due, however, to the open pivotal bearing of the contact device, and its yieldable connection with the block, no point of weakness is defined and when the spring is called upon to flex it may do so throughout its entire length.

Of course, the freedom from corrosion is due to the wiping contact between surfaces 42 and their respective contact heads 25, while a face to face engagement exists between these parts.

lill) Freedom from pitting is attributable to the fact that the wiping action is repeated during the opening movement of the Switch, thecontacts remaining in engagement until the switch lever has acquired a comparatively rapid rate of movement and the parts have assumed a position such that they will separate with comparatively high speed.

I claim:

1. In a device of the character described, the combination with a contact and a support, of a curvilinear contact member, fulcrumed adjacent said support, and comprising a resiliently flexible arm terminating in a contact portion normally spaced from said contact, a spring normally holding said member to said support, and a lever pivoted to act upon said member in a direction to oscillate it against the compression of said spring in a direction to bring said portion into engagement with said contact, said lever being adapted to act upon said flexible arm whereby to wipe said portion upon said contact, and said arm being adapted to spring beyond its normal position subject to shock of engagement with said support whereby to break any arc formed upon separation of said contact portion from said contact.

2. In a. device ofthe character described, the combination with a contact and -a movable contact member comprising a flexible arm and a contact portion, of a stop adjacent which said member is fulcrumed, a spring pressing said member toward said stop, and a lever provided with an extremity normally positioned laterally adjacent said arm and oscillatable toward said arm in a direction to press said member from said stop bodily about its fulcrum and to engage said portion with said contact, the said arm being disposed in the path of continued movement of said lever in a position to be flexed thereby, whereby to move said portion against the face of said contact subsequently to engagement of said portion therewith.

3. In a device of the character described, the combination with a relatively fixed contact and a movable contact member provided with a contact engaging portion and pivoted for movement in a direction to effect engagement of said portion with said contact,V of stop means normally defining the position of said member, a spring normally holding said member to said stop means, and a lever pivoted in proximity to said stop means and normally disposed adjacent said member, said lever being oscillatory against said member in oppo-v sition to said spring, whereby to be adapted to adjust said member in a direction to effect engagement between said portion and said contact, said member being curved and flexible adjacent saidlever, whereby the continued movement of said lever is adapted to ex said member and thereby to move said portion with respect to said contact subsequent to such engagement.

4. In a device of the character described, the combination with a relatively xed contact, of a movable contact member provided with a contact engaging portion, a stop means providing an open pivotal bearing for said member, and a resiliently yieldable supporting mechanism urging said member toward said stop means out of engagement with said contact, and comprising, with said stop means, the only mounting and guide for said member.

5. In a device of the character described, the

combination with a relatively xed contact, of a movable contact member provided with a Contact engaging portion, a stop means providing an open pivotal bearing for said member, and a resiliently yieldable supporting mechanism urging said member toward said stop means out of engagement with said contact, and comprising, with said stop means, the only mounting and guide for said member, together with a lever fulcrumed for engagement with said member in opposition to said resiliently yieldable supporting mechanism.

6. In a device of the character described, the combination with a contact, of a stop means, a flexible contact member mounted for oscillation between said stop means and said contact and provided with a portion adapted for at face engagement with said contact and a curved arm supporting said portion, and a lever provided with an extremity normally disposed adjacent a part of said arm and adapted to act laterally upon said arm across the curved surface thereof whereby initially to adjust said portion into face engagement with said contact and subsequently to flex said arm whereby to adjust said portion in wiping engagement with said contact.

'7. The combination with a relatively xed contact and a stop block spaced therefrom, of a contact member having its extremity pivotally seated adjacent said stop block and provided with a flexible curved arm supporting a contact portion adapted for engagement with said contact in the pivotal movement of said member, a spring normally supporting said member against said block with said portion out of engagement with said contact, and a lever normally positioned adjacent said ilexible arm and engageable therewith in a direction adapted to oppose said spring and to oscillate said member to bring said portion into engagement with said contact, said lever and said arm being formed and disposed for interaction in the subsequent movement of said lever in a direction to ex said arm and to adjust said portion in engagement with said contact.

8. In a device of the character described, the combination with a contact and a stop block, of a spring guide projecting from said stop block toward said contact, a compression spring carried by said guide and acting toward said block, a movable contact member including a leg portion seating adjacent said block and interposed between said spring and said block for pivotal movement to and from said block under compression of said spring, and a eXible arm connected with said leg portion and carrying a contact portion adapted for engagement with said contact in the pivotal movement of said leg from said block, and a single means for moving said member pivotally to effect said engagement and for subsequently flexing said arm.

9. In a device of the character described, the combination with a contact and a stop block, of a spring guide projecting from said stop block toward said contact, a compression spring carried by said guide and acting toward said block, a movable contact member including a leg portion seating adjacent said block and interposed between said spring and said yblock for pivotal movement to and from said block under the compression of said spring, and a flexible arm connected with said leg portion and carrying a contact portion adapted for engagement with said contact in the pivotal movement of said leg from said block, and a single means for moving said fio member pivotally to effect said engagement and for subsequently flexing said arm, said means comprising a lever pivoted for movement between an off position adjacent said arm and an on position in which the central radius of said lever is substantially aligned with the thrust of said arm thereon.

10. In a device of the character described'a combination with a relatively xed contact and a stop means spaced therefrom, of a contact member normally seating against said stop means and including a floating leg portion and curved flexible arm and a contact portion carried by said arm in a position for engagement with said contact, a spring normally pressing said member into engagement with said stop means, and a lever adapted to act upon said arm to effect an initial bodily pivotal movement of said lever in a direction to engage said portion with said contact and a subsequent wiping movement of said portion on said contact, said lever being pivoted adjacent said arm for oscillatory movement between an off position in which itsextremity is laterally disposed with reference to said arm, and an on position in which the extremity of said lever is substantially aligned with the thrust of said arm thereupon.

11. In a device of the character described, the combination comprising a relatively iixed contact, a flexible member provided with a floating mounting and having a portion engageable with said contact in the bodily movement of said member, a stop with which said member is normally engaged, means opposing the movement of said member from said stop in a direction to effect such engagement, and a lever oscillatably adjacent .to an intermediate portion of said member and adapted initially to displace such portion, and subsequently to flex it, the contact portion of said member being adapted to whip away from the fixed contact when said member encounters said stop upon release of the engagement of said lever therewith.

12. In a device of the character described, the

combination with a pair of spaced contacts and an intermediate terminal block, of a pair of contact members normally seated against said block, including portions normally in spaced relation to said contacts, spring means pressing said members toward said block at opposite sides thereof, and a switch lever pivoted intermediate said members adjacent said block alternatively engageable with either member in a direction to force its said portion into engagement with the respective contact.

13. In a device of the character described, the combination with spaced contacts and an intermediate stop means, of a pair of oppositely disposed switch members normally abutting said stop means and pivoted for oscillatory movement to engage said contacts, a spring means pressing said members toward said stop means. a guide for said spring means. and an actuating lever positioned intermediate said members and alternatively engageable therewith to oscillate either member selectively to engagement with its respective contact.

14. The combination with a pair of spaced contacts and an intermediate block, of a lever adjacent said block, oating switch members posi- ,tioned at opposite sides of said block and engageable with respective contacts, each of said members including a leg portion normally abutting said block in face contact therewith and extending therebeyond into proximity to said lever, a.

curvilinear arm in a position to be acted on by said lever and extending from said leg portions to contact portions normally spaced from their respective contacts and engageable selectively therewith when said lever acts upon the respective arms.

15. The combination with a single actuating lever and relatively fixed contacts at either sid thereof, of a central terminal intermediate said contacts, movable contact members pivoted at said terminal and disposed in spaced relation at either side of said lever with laterally extending arms curved adjacent said lever for interaction therewith, stop means between said members adapted to define a normally open position in which said members are out of engagement with their respective contacts, and spring means urging said members to said stop means, each of said members being bodily yieldable in opposition to said spring means under the action of said lever to the point of engagement with the respective contact and being subsequently flexible under the continued action of said lever whereby to wipe said contact.

16. The combination with a single actuating lever and relatively fixed contacts at either side thereof, of a central terminal intermediate said contacts, movable contact members pivoted at said terminal and disposed in spaced relation at either side of said lever with laterally extending arms curved adjacent said lever for interaction therewith, stop means between said members adapted to dene a normally open position in which said members are out of engagement with their respective contacts, and spring means urging said members to said stop means, each of said members being bodily yieldable in opposition to said spring means under the action of said lever to the point of engagement with the respective contact and being subsequently flexible under the continued action of said lever whereby to wipe said contact, said members and said lever being so formed that in the ultimate position of said lever the reaction of either member thereon will be substantially aligned with the central radius of said lever.

17. A device of the character described including a switch casing, a pair oi' spaced terminal contacts in saidcasing and an intermediate terminal therein, said contacts and said terminals being mutually insulated, a pair of movable contact members engageable with respective conltacts and comprising conductors having leg portions in open pivotal bearing upon said terminal and laterally projecting resiliently flexible arms carrying contact portions engageable with respective contacts, stop means normally abutted by said leg portions, a lever fulcrumed with respect to said casing and provided with an extremity interposed between said arms and adapted selectively to engage either upon oscillation of said lever, and spring means supporting said leg portions normally against said stop means with said contact portions out of engagement with their respective contacts.

18. A device of the character described including a switch casing, a pair of spaced terminal contacts in said casing and an intermediate terminal therein, said contacts and said terminals being mutually insulated, a pair of movable contact members engageable with respective contacts and comprising conductors having leg portions in open pivotal bearing upon said terminal and laterally projecting resiliently flexible arms carrying contact portions engageable with respective contacts, stop means `normally abutted by said leg portions, a lever fulcrumed with respect to said casing and provided with an extremity interposed between 'said arms and adapted selectively to engage either upon oscillation of said lever, a spring means supporting said leg portions normally against said stop means with said contact portions out of engagement with their respective contacts, said spring means being more freely yieldable under the action of said lever than said arm, whereby said members will move bodily when acted upon by said lever until their respective contact portions engage the respective contacts, the length of the lever and the formation of each member being such that the continued movement of the lever will flex the respective arms to wipe the respective contact portions across the respective contacts.

19. A device of the character described including a switch casing, a pair of spaced terminal contacts insaid ,casing and an intermediate terminal therein, said contacts and said terminals being mutually insulated, a pair of movable contact members engageable with respective con,

tacts and comprising conductors having leg portions in open pivotal bearing upon said terminal and laterally projecting resiliently flexible arms carrying contact portions engageable with respective contacts, stop means normally abutted by said leg portions, a lever fulcrumed with respect to said casing and provided with an extremity interposed between said arms andadapttively xed contact of a mounting block, a relatively movable contact fulcrumed for non-flexing movement for oscillation with respect to said block into engagement with said xed contact, spring means urging said .movable contact in a direction of oscillation away from said fixed contact, and an actuating member arranged to act upon said movable contact at a point between said spring means and said xed contact, said movable contact being ilexible adjacent that point.

21. In a switch, the combination with amounting block, ofv a relatively movable contact having a portion mounted for oscillation with respect to said block, a spring carrier reciprocable with reference to said block, a spring mounted on said carrier in opposition to the oscillation of -said movable contact portion and a second spring opposing the reciprocation of said carrier whereby to supplement the action of said first spring in opposing oscillation of said portion, together with a relatively xed contact adapted to be engaged by said portion in the course of its oscillation.

22. In a device of the character described, the combination with a fixed contact and a support, of a movable contact having one end' pivotally mounted on said support and its other end engageable with said fixed contact, an'actuating lever for said movable contact, and a resilient support for the movable contact engaged with the latter at a pointv intermediate the pivotal point of the movable contact andthe point of engagement between the actuator and the movable contact.

23. In a device of the character described, the

combination with a xed contact and a support, of a resilient movable contact having one end pivotally mounted on said support to permit nonflexing movement of said contact and its other vend engageable with said fixed contact, and an actuating lever for said movable contact engageable with the latter intermediate the ends thereof.

24. In a device of the `character described, the

combination with a fixed contact and a support, of a stop on said support, a movable contact having one end pivotally mounted on said support adjacent said stop and its other end engageable with said fixed contact, an intermediate portion abutting said stop, and an actuating lever for said movable contact engageable with the latter intermediate the ends thereof.

25. In a device of the character described, the combination with a xed contact and a support,

of a stop on said support, a movable contact

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