US2533671A - Method and means for mounting snap action switch blades - Google Patents

Description

Dec. 12, 1950 JACOBS JR 2,533,671

P. C. METHOD AND MEANS FOR MOUNTING SNAP ACTION SWITCH BLADES Filed April 13, 1948 Patented Dec. 12, 1950 METHOD AND MEANS FOR MOUNTING SNAP ACTION SWITCH BLADES Philip 0. Jacobs, Jr., Newtonville, Mass assignor,

by mesne assignments. to The Acro Manufacturing 00., Columbus, Ohio 1 Application April 1a, 1948, Serial No. 20.656

8 China.

This invention relates to snap action switches and is particularly concerned with the provision of a mounting for a snap action switch blade which will permit the blade to be mounted'and adjusted for a desired operating force in a minimum time and with the required precision.

One of the difliculties in the manufacture of snap action switches has been to make the blades in quantity and still of such uniformity that their operating characteristics will be within the tolerances required. In switch blades of this type the snap action effect is obtained either by stamping the blade in a die to deform a certain critical area of the blade or by drawing the legs of the blade together a certain amount to produce a deformation in the body of the blade similar to that produced by stamping. 3'

However, even under the most carefully controlled conditions, it has been found to be a practical impossibility to produce switch bladesin quantity which, when mounted for use in the switches, will have the same operating characteristics. It has therefore been necessary to provide means for making individual adjustments to the switch blades after mounting so that switches of a given type or class will have uniform characteristics. In some instances it is impossible to make these adjustments, in which case the switch must be rejected, thereby raising the cost of the others. Another element contributing to non-uniformity in quantity'production is a. small variation in the metal from which the blades are made.

In any event, the problem of uniformity in operating characteristics is real and has proved expensive. It is therefore the object of the present invention to provide means for mounting a conventional switch blade of a type now in use in such manner that after mounting it may be adjusted to operate at any desired pressure. It will be understood by those familiar with this art that-the more the legs of a switch blade are toed in, the greater will be the required operating force. Therefore, the invention contemplates that the blade will flrst be mounted in a position where there is little or of the legs and thereafter thelegs may be progressively toed-in until the proper operating force is attained.

when the legs have reached a position giving the right characteristics to the blade, then the mounting and legs are left and no further change takes place. The means used for drawing the legs of the switch blade together is oi. a simple character, but nevertheno toe-in in that position,

less lends itself to great precision. Furthermore, the adjustment may be accomplished rapidly and at low cost, and blades which otherwise would give widely varying operating characteristics may be used in a line of switches with a uniformity that would otherwise be impossible.

The nature of the invention will be more clearly understood as the description proceeds with the aid of the accompanying drawings, in which Fig. 1 is a vertical cross-section of a switch utilizing the mounting means of the present invention.

Fig. 2 is a plan view of the switch mechanism shown in Fig. 1 with the housing cover removed.

Fig. 3 is a section on the line 3-3 of Fig. 2 but prior to the adjustment of the blade.

Fig. 4 is a section on the line 4-4 of Fig. 1, showing the mounting after adjustment has been completed.

Fig. 5 is an exploded view of the switch blade and mounting means, the assembled parts of which are shown in Fig, 3.

Fig.6 is a sectional elevation corresponding to Fig. 4, showing a modified form of the invention.

Fig. '7 is a vertical cross section on the line 1-4 of Fig. 2, showing a variation in the mounting means for modifying the contact pressures.

Referring to Fig. 1, the snap action switch shown therein comprises a housing having a base so 2 and a cover 4. Within this housing are mounted the elements of a snap action switch which consist of a blade 6, a pair of contacts 8 and It,

a mounting support generally referred to at l2 for the fixed end of the blade, and a push but- 35 ton l4 located where it may exert the necessary force on the blade to cause actuation.

The construction of the switch housing, blade and operating means is conventional, the inven- ,tion residing in the means by which the 40 is mounted and the adjusting mechanism that is included therein.

The switch blade 6 is plainly shown in Figs. 2 and 5. When mounted in the manner hereinafter described, the movable end contact l8 alternately comes into engagement with contacts 8 and Ill as the blade is actuated. In the present instance the normal position of the switch' blade will have contacts i0 and IS in engagement. When the operating button II is pressed downwardly the blade will snap up to an unbalanced position with contact IS in engagement with contact or stop 8. Thereafter, when push button it is released, the blade will return to the stable down position shown in Fig. 1.

In the particular blade construction shown blade herein, there are a pair or legs I. and 28 which extendirom the blade body to the support l2. A centrally located tongue 22 constitutes the operating lever against which button 14 is pressed. In order that the body of the blade may be suitably arched at the critical area 24, which area reverses itself by snap action upon pressure on tongue 22, it is necessary that legs i8 and 28 be toed-in, as shown in Fig. 2, a greater or less degree. The more these legs are toed-in, the more area 24 will be arched and the more the torce required against tongue 22 to cause the blade to snap. It will be noted in Fig. that blade 6 before assembly has legs I! and 20 in fiat untoed-in position, and there is, of course, no arched critical area as yet at 24.

The construction of the mounting support l2 in relation to the legs i8 and 20 constitutes that partoi' the invention that makes rapid adjustment possible. The base 2 has a projection 2| extending upwardly therei'rom shaped as a 1'. The crossbar 28 is merely a reinforcement for the base and is not concerned with the invention. The legs i8 and 20 are notched at their ends as at 28 and 22 to produce short fingers 24 and It. The blade 6 is positioned on support 26 with the fingers It and 86 overlying in part the short leg 28 01' support 28. A spacer 40 similar in shape to support 26 is placed on top of legs' I! and 28 with hole 42 aligned with hole 44 of support 28. A clamp 48 having a pair of partially downturned clamping members 48 and 80 is then placed on top of spacer 40 and the parts are all secured together in the present instance by the bolt 52 and nut 54, plainly shown in Figs. 1 and 2. It will be understood that other securing means, as a rivet, for example, may be used it 'lhusitisseenthatasimpleandconvenient mounting means has been provided whereby a spring bladehavingnosnapactioncharacteristics when initially mounted may be quickly and simply-adjusted to give it the characteristics required within any set tolerances.

The'object oi theincliulon of spacer ll is to makeitpossibleiorthemembergllandllto besqueeaedagainstfingersflandllinagenerally horizontal direction. It spacer II were omitted, it is apparent that the initial pressure of members 4| and II would be less eilective to move fingers 24 and II toward each other. However, by providing a modified form or clamp. such as is shown in Fig. 6, the spacer may be-omitted. Here the clamp 88 has clamping members It and II which are first turned upwardly as-at l2 and 04 before being bent down to blade-engaging position. By this construction the iulcrum about which the members 88 and II pivot is been contemplated that the 1888 i8 and 20 will preferred. When the nut is set up snugly but With the parts in this assembled position, the

legs i8 and 28 will be without any toe-in, and there will be as yet no snap action characteristic to spring blade 6. A suitable tool is then applied to members 48 and 58, squeezing them together to bring pressure to bear on fingers 34 and 38. This pressure is great enough to overcome the existing clamping force exerted on legs l8 and 20 by spacer 48 under the pressur exerted thereon by clamp 46. Thus the legs l8 and 20 are gradually drawn together, and as this occurs, arching of the critical area 24 commences and the blade develops snap action characteristics. When the toeing-in of the legs has proceeded only a slight distance, then only a very small force will be required against tongue 22 to cause blade actuation. As the legs are drawn together more and more, the force to operate the blade will increase. By suitable scales and other measuring devices it is possible to continue the drawing together of legs l8 and 28 until they reach a point where a desired predetermined force is required against tongue 22 to operate the blade. At this point the squeezing together of members 48 and ceases. The friction under which the legs find themselves at this time is adequate to maintain them in the final set position. Fig. 4 is illustrative of the position mem-- bers 48 and 50 may assume by the time the required toeing-in has reached completion.

be clamped initially in the same horizontal plane and that their movement toward each other as adjustment proceeds will likewise be in the sam plane.

A blade thus mounted and stressed has a stable position in which contact I! rests against contact l8 and an unstable position with contact it against contact 8 reached after button i 4 has been depressed sufilciently to cause blade actuation. The pressure between contacts I! and III in the stable position in normal mounting position is less than the pressure between contacts i8 and 8 in the unstable position. This condition may be undesirable in some instances, and accordingly the invention also includes a modified form of mounting means and blade formation which makes it possible to control or adjust the stable and unstable contact pressures as may be required. The variation may be brought to a point where the stable and unstable contact pressures are substantially equal.

The mounting and blade formation that achieve this result are shown in Fig. "l. The base 2 has a projection or supporting member 10 in general similar to support 26. The upper surface 12, however, instead of being fiat, slopes downwardly toward the sides at those areas against which the legs of the blade normally rest. The angle of the slope on each side as at 74 and 18 is substantially equal, so that the angle of twist of the blade legs will be equal and the parts otthe blade symmetrical. The clamp 18 corresponds to the clamp 86 shown in Fig. 6. It a spacer is .used, the clamp would correspond to clamp 46 shown in Fig. 5. In any event, clamp 18 is so shaped that when it is drawn downwardly to squeeze legs l8-and 28 against support I8 the legs will be twisted slightly, as shown. The clamping action between clamp 14 and support III will be spread over both surfaces of the legs 18 and 28 at the fiat areas of contact, so that the gripping of the legs will be just as secur A as in the forms heretofore described.

After the legs have been gripped in this twisted condition, the inwardly operating force is then applied to the leg extensions, so that the two legs, while being brought together, slide upwardly slonatheinclinedsurfaces'llandiiuntilthe desired operating characteristics are reached.

The effect of this construction is to cause the contacts in stable position to exert a greater pressure on each other and the contacts in unstable position to exert a less pressure on each achieving uniform operating characteristics in switches produced in quantity, but also permits varying of the relative contact pressures through the simple expedient of providing supporting blocks Ill having upper surfaces of varying slopes.

In general it is preferred that slopes H and It be equal, so that the twist in the blade legs will be equal and symmetrical. clamp 18 is pre-' formed to have an overall angulflrity that will be somewhat more acute than the angularity between faces II and 'Ilfso that as the clamp is drawn down against the top of the blade legs it will nex slightly until the compressive force is applied generally over the entire overlapping areas.

while preferred forms of the invention have been shown and described, it is to be understood that the invention is not to be limited thereby but only by the appended claims.

I claim:

1. A mounting for a snap action switch blade having a pair of legs which must be toed in to give the desired operative effect, said mounting comprising a base, a support on said base of sufllcient width to engage the under fiat areas of the ends of said legs when said blade is placed thereon, a clamp adapted to overlie the upper surfaces of the ends of said legs, said clamp having a pair of oppomtely disposed downturned members integral with said clamp for engaging the outer edges of the ends of said legs, and

means for drawing said clamp toward said support whereby said legs may be clamped therebetween and said' downturned members will be in a position to engage and move said leg ends toward each other.

, 2. A mounting for a snap action switch blade having a pair of legs which must be toed in to give the desired operative effect, said mounting comprising a base, a support on said base of sufficient width to engage the under flat areas of the ends of said legs when said blade is placed thereon, a clamp adapted to overlie the upper surfaces of the ends of said legs, said clamp having a pair of oppositely disposed downturned members integral with said clamp for engaging the outer edges of the ends of said legs, a portion of each of said members adjacent the body of said clamp being bent upwardly above the top surface of said clamp, and means for drawing said clamp toward said support whereby said legs may be clamped therebetween and said downturned members will be in a position to engage and move said leg ends toward each other.

3. A snap action switch comprising a base, a support on said base, said support being of nonuniform width, a snap action switch blade having a pair of legs which must be drawn together to give the required snap action characteristics to said blade, said legs positioned on said support and frictionally maintained in said position by a spacer blade positioned on the upper surface of the ends of said legs, a clamp above and resting on said spacer, means for compressively holding the parts together to secure said legs firmly in position. the outer edges of the ends of said legs when inunstressed position being farther apart than the width of that part of the support which they overlie, downturned members integral with said clamp positioned where they may engage the said outer edges of said legs whereby, upon the application of a superior force to said members, said members may be bent toward each other to engage and move said legs toward each other until the desired operating characteristic of the switch blade has I been obtained.

4. The combination of a mounting and a snap action switch blade having a pair of legs which must be toed in to produce the desired operative effect, said mounting comprising a clamp having two non-parallel engaging surfaces sloping toward each other for frictionally gripping said legs on their opposed surfaces and at a symmetrical angle to each other, so that said legs when gripped at their ends are slightly twisted, a portion of each of said legs extending beyond said clamping means, and means constituting part of said clamping means by which a compresSive force may be transmitted simultaneously to the said ends of the said legs in the direction of the plane of each clamped end of said blade, whereby when said force is suflicient to overcome the said clamping force, said legs may be moved toward each other while still being gripped by said clamp.

5. A snap action switch comprising a base, a support on said base, a clamp above said support, means for drawing said clamp and support together, a snap action switch blade having a pair of legs, said legs being positioned between said support and said clamp, the areas on said support and said clamp in contact with one of said legs being at an angle to the areas on said support and said clamp that are in contact with the other of said legs, means for applying sumcient clamping force to said support and clamp to maintain said legs wherever they may be set with respect to said clamp, said legs extending beyond the said clamping areas to provide por- .tions which may be-engaged bymeans of sumcient strength to move said legs toward each other by overcoming the gripping force of said clamp.

6. The method of adjusting a snap action blade of the type having legs that must be toed-in to give the required characteristics. said method comprising the steps of clamping said legs in symmetrical twisted positions with the clamped portions lying in non-parallel planes, applying to each leg at its outer edge near the end thereof a force in the direction of the plane of each clamped leg, said force being of sumcient degree to overcome said clamping force wherebytoe ing-in of said legs is progressively accomplished, testing for operating characteristics as the toeing-in of said legs progresses and thereafter, when the required characteristics have been reached,

' holding said legs with sumcient restraining force to prevent their subsequent displacement during normal use.

7. A mounting for a snap action switch blade of the type having a pair of legs which must be toed-in to ive the desired operative effect, said mounting comprising a base, a support on said base having spaced non-parallel areas sloping toward each other, said non-parallel areas positioned to engage the under flat areas of the ends of said legs when said blade is placed thereon, a

positely disposed downturned members intesral with said clamp iorvensaslns the outer edges oi sliding movement of said legs toward each other upon the application of a superior inward force to the ends or said legs, said srippins surfaces thereaiter maintaining said less in a position where said less are oppositely twisted and toed-in toward each other to produce a blade with snap action characteristics. a contact on a movable part of said blade and a contact on said base position for stable and separable engagement with said blade contact. said twisting and toeinsin of said less producing a greater pressure between ssid contacts in stable position for the amount or teed-in movement than would be ob- 10 with the lm in untwisted condition.

PHILIP C. JACOBS. Ja'.

summons mm The iollowins references are oi record in the 16 tile 0! this patent:

UNITED s'rn'ms ra'mn'ra Number Name Date 1,708,198 Sherwood Apr. 9, 1929 m 2,275,642 Nordbers Mar. 10. 1942 2,300,489 Deutschmann Nov. 3, 1942 2,324,798 Nordbers July 20; 1843

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