US3291931A - Oblong end opening switch construction - Google Patents

Description

Dec. 13, 1966 G. ROGERS 3,291,931

OBLONG END OPENING SWITCH CONsTRUCTION Filed July 12, 1965 5 Sheets-Sheet 1 INVENTOR.

GILBERT ROGERS BY MW HIS ATTORNEYS Dec. 13, 1966 5. ROGERS 3,291,931

} OBLONG END OPENING SWITCH CONSTRUCTION Filed July 12, 1965 v I 5 Sheets-Sheet 2 INVENTOR.

GILBERT ROGERS HIS ATTORNEYS Dec. 13, 1966 ROGERS 3,291,931

OBLONG END OPENING SWITCH CONSTRUCTION Filed July 12, 1965 I5 Sheets-Sheet 5 v FIG-l2 INVENTOR. FIG |4 GILBERT ROGERS AB m7- HIS ATTORNEYS Uite States Patent C P Filed July 12, 1965, Ser. No. 471,310 Claims. (Cl. 20067) This invention relates to a rolling spring switch construction.

One of the features of this invention includes the use of an arcuate, flexible, thin, hard metal, elongated, leaf spring which is free of local stress producing sharp bends, notches and internal corners and including tongue receiving openings each of which is free of local stress producing sharp bends, notches and internal corners.

This invention greatly improves the operation and effective life of a snap acting leaf spring switch construction which is provided with a thin, elongated leaf sna spring made of high tensile strength metal, such as is disclosed in the patents to E. F. Kohl, 2,237,705, granted April 8,1941; 2,458,518, granted January 11, 1949;

2,558,219, and granted June 26, 1951; and 2,558,258,

granted June 26, 1951; and the patent to V]. E. Rhodes, 2,927,171, granted March 1, 1960.

Elongated high tensile strength metal snap springs have been successfully made for many years, in accordance with said patents. Switch constructions using such snap springs have been and are being very favorably accepted in commerce.

One of the outstanding features of such previously and presently produced snap springs, made in accordance with said patents, is their flexible, thin, hard metal, leaf construction which provides long life and accurate switch operation. However, their tongue receiving openings do not have the features of this invention, and therefore do not have the surprisingly long life attained by the snap springs of this invention.

The improvements provided by this invention retain the accuracy of such previously and presently produced leaf snap springs according to said patents and surprisingly increase their previously long life of operation.

Extensive comparative tests have established as much as a 10 or to 1 increase in the mechanical life of switch constructions having leaf springs made and operated according to this invention in comparison with the previously and presently produced commercial switch constructions made according to said patents, but having leaf springs which do not embody the present invention.

Other features of this invention will become apparent from this description, the appended claimed subject matter, and/ or the accompanying drawings, in which:

FIGURE 1 is a bottom view of a switch construction according to this invention and shown in actual scale.

FIGURE 2 is a plan view of a switch construction which embodies this invention, such as is shown in FIG- URE 1, but drawn in an enlarged scale.

FIGURE 3 is a diagrammatic plan view of an unarched leaf spring and cooperating fulcrum members, according to this invention, and shown in unassembled condition.

FIGURE 4 is an enlarged diagram of a tongue receiving opening, according to this invention.

FIGURE 5 is a view, somewhat similar to FIGURE 3, and showing another embodiment of an unarched leaf spring, and cooperating fulcrum members, according to this invention, in unassembled condition.

FIGURE 6 is an enlarged cross section of an arched leaf spring member as shown in FIGURES 3 and 5, and showing tongues of the cooperating fulcrum members inserted in the tongue receiving openings.

FIGURE 7 is an upward cross section taken along the line 7-7 of FIGURE 6.

FIGURE 8 is a diagrammatic view of an end of a leaf spring, such as shown in FIGURES 3 and 5, and showing another embodiment of the tongue receiving opening, according to this invention.

FIGURE 9 is a view somewhat similar to FIGURE 8, and showing a further embodiment of a tongue receiving opening, according to this invention.

FIGURE 10 is a view somewhat similar to FIGURES 8 and 9 and showing a further embodiment of a tongue receiving opening, according to this invention.

FIGURE 11 is a diagrammatic view taken substantially along the line 11- 11 of FIGURE 2, and showing a tongue of suitable width and thickness.

FIGURE 12 is a diagrammatic cross section taken along the line 12-12 of FIGURE 11.

FIGURE 13 is a view similar to FIGURE 11, and showing another tongue of suitable width and thickness.

FIGURE 14 is a diagrammatic cross section taken along line 14-14 of FIGURE 13.

FIGURE 15 is a reduced scale cross section taken along line 1515 of FIGURE 2.

FIGURE 16 is an inside view of the cover for the switch.

Certain words are used in this specification and in the claimed subject matter which indicate direction, relative position, and the like. However, it is to be understood that such words are used in connection with the illustrations in the drawings, and that, in actual use, such parts may have entirely different direction, relative position and the like. Examples of such words are upper, lower, vertical, horizontal, etc.

As disclosed in said Kohl and Rhodes patents, an arcuate leaf spring, for snap acting switches, may be made from a thin flat piece of resilient metal, which, when in use, has a relatively high tensile strength, and forms a flexible, thin, hard metal, elongated leaf spring. Examples of conditions which may prevail in such a leaf spring are described in the said Rhodes patent, column 5, lines 31+, such as follows:

The principal limiting conditions on the arcuate spring for snap-acting switches such as here involved, include the following: 4 (a) Maximum Width 0.5 inch. (b) Minimum width-0.093 inch. (c) Maximum thickness0.008 inch.

(d) Minimum thickness-0.00l5 inch.

(e) Maximum tensile strength300,000 p.s.i.

(f) Minimum tensile strength-160,000 p.s.i.

(g) Radius of the rolling spring in different switches usually varies from about 0.1 to about 0.25 inch but could be larger for large size switches.

(h) Spring materials usually used include: beryllium copper; 17-7 PH stainless steel; high carbon spring steel; and Elgiloy.

A typical thin ribbon or strip of stock, from which such rolling springs may be cut by stamping or the like, may be substantially inch wide, .0025 inch thick, and in the order of from 180,000-250,000 p.s.i. tensile strength. Such a strip or ribbon, if folded substantially to 180 and pressed by a finger to form a crease and then is opened, substantially to flat condition, will break at the crease and be completely severed. This is a test of high strength. Notwithstanding such high tensile strength, leaf springs made from such stock material, and formed with end openings, according to the disclosures of the Kohl patents and the Rhodes patent, and used in arched constructions, as disclosed in said patents, have been tested between 1,000,000 and up to 5,000,000 flexing cycles, in switches of the character herein shown in FIGURE 2, with up to failure at the 5,000,000 mark. Leaf springs made of similar material, and similar construction, except that the end tongue receiving openings have been made according to this invention, have been tested in similar switches, and have run up to and over 65,000,000 cycles without failure.

This remarkable improvement has been achieved by constructions embodying this invention. One of such embodiments will now be described in connection with FIGURES 1-4, 6 and 7 of this application.

By way of example, and merely typical of many switches within which this invention may be used, a switch construction according to this invention may be embodied in a switch construction 10, as indicated in FIGURES 1 and 2. Such a switch construction is shown in actual size in FIGURE 1, of applicants application drawings. That is, the entire casing main body may be approximately 1 inches long, 35 inch wide, and inch thick excluding the outside electrical connectors, and the actuating plunger.

Such a switch construction may have a main outer casing 12 with a removable cover 13. A- more detailed disclosure of the casing 12, and of its cover, may be found in the patent to Wodtke, 3,176,109, granted March 30, 1965.

Such a casing 12 may contain a leaf spring actuating and first fulcrum member 14, which may have a first protruding tongue 16, and a respective leaf spring engaging edge shoulder 18, 18 on eachside of the tongue 16.

A leaf spring actuated second fulcrum member 20 may have a second protruding tongue 22 aligned with the first tongue 16. Su-ch second fulcrum member 20 may have a respective leaf spring engaging shoulder 24, 24 on each side of the second tongue 22.

A flexible, thin, hard metal, elongated leaf spring 26 may be provided, which is free of local stress producing sharp ends, notches and corners. Such leaf spring 26 may have a main body 28, which is shown in its arcuate condition in FIGURES 6 and 7, and in flat condition in FIGURE 3. The leaf spring member 26 also may have rocking end portions 30 and 32 which engage the respective ones of the edge shoulders 18, 18 and 24, 24. The end portions 30 and 32 are free of line fold deformation and engage the shoulders 18, 18 and 24, 24 with substantially straight surfaces which are extensions of said arcuate main body 28, as shown in FIGURE 6.

The end portions 30 and 32 each have a respective tongue receiving oblong opening 34 which is free of local stress producing sharp bends, notches and internal corners. Each of said openings 34 loosely confines the sidewise and endwise movement of the leaf spring 26 to maintain such elongated leaf spring 26 substantially aligned between the fulcrum members 14 and 20.

Each opening 34 may be an elongated, oblong opening, and, for example, may be substantially elliptical in shape, as shown in FIGURES 3 and 4. Such openings 34 may be elliptical, within the meaning of the usual draftsmans ellipse. That is, the ellipse may be drawn or produced by two opposite circle arcs 36, 36, each having a relatively long radius 38, 38. Each ellipse 34 may also have opposite short circle arcs 40, 40, which form the ends of the ellipse, and each of which has a short radius 42, 42. The ends of the arcs 36, 36 merge with the ends of the arcs 40, 40, to form the complete ellipse, as is well known in drafting practice. For all practical purposes, such draftsmans ellipse may be considered the equivalent of a true mathematical ellipse, or any ellipse-like construction that may be used, in accordance with this disclosure.

The space encompassed by the long circle arcs 36 may loosely contain the tongue 16 (or 22 as the case may be). The width of the ellipse at the endsof the merged arcs 36 and 40 may be a sufiicient distance, loosely to cooperate with the thickness of the tongue 16 (or 22, as the case may be) to maintain the leaf spring aligned between the fulcrums 14 and 20. The corner edges of the fulcrum pieces 14 and 20, and of the openings 34 all burs, so that the parts may cooperate without damage.

The general relationships of the elliptical openings 34 to the width and thickness of the tongues 16 and 32 are more fully shown and described elsewhere in connection with FIGURES 11-14.

The elongated leaf spring 26, may, if desired, be made in accordance with the disclosure in the Rhodes Patent 2,927,171, with the exception that the openings 58, shown in FIGURE 4 of the Rhodes patent, are to be made in accordance with this invention, such as is illustrated and described herein.

As a specific example, the leaf spring shown in FIG- URES 3 and 4 (and FIGURES 6 and 7) when made in accordance with the Rhodes patent, may have a thickness of .0025 inch and may be made from a ribbon or strip with a stock width of 1 inch and may be made of 17-7 PH stainless steel as specified in the Rhodes patent and may have from 210,000-235,000 psi. tensile strength. The radius of curve 48 may be .312 inch, and the radius of curve 50 may be .015 inch. The width 52 may be .125 inch. The length 54 of the ellipse 34 may be .050 inch and the width 56 of the ellipse may be .022 inch. The length 58 of the leaf spring may be .492 inch and the distance 60 between the inner edges of the lips of the ellipse at each end may be .390 inch more or less.

The long radius 38 of the draftsmans ellipse may be .050 inch in length, while the short radius 42 may be substantially .005-.006 inch in length, more or less, so that the short and long radii may be merged to form a draftsmans ellipse, as is well known.

The shape of the openings in the leaf spring is an important feature of this invention. Various types of tongues may be used with such openings. FIGURES 11-14 show some of such various tongues to be used with the openings 34.

FIGURES 11 and 12 show the opening 34 of the leaf spring 28 receiving a relatively thin tongue 22A which has a suitable tongue width and thickness to be used with the elliptical openings 34, 34 at either end of the leaf springs herein disclosed, such as leaf spring 26 of FIG- URES 2-4 and 6, 7.

The tongue 22A is emblematic of either tongue 16 or 22, and may have a width and thickness that allows sufiicient tolerances to permit proper play between the tongue and the leaf spring 26 during the snap actions. The opening 34 in the leaf spring 26 loosely confines the sidewise and endwise movement of the leaf spring 26 to maintain such leaf spring substantially aligned between the fulcrum pieces 14 and 20.

For example, the tongue 22A may have a width 57A equal to the distance between the centers 59 of the short radii 42, which distance 57A may be .040, more or less in the typical size herein given. The thickness 61 of the tongue 22A may be .003 inch, more or less. Such thickness has been found to be a suitable minimum sufliciently thick for the puropses of this invention.

The angle X between the planes of the leaf spring 28 and tongue 22A may be as much as 82 to receive the tongue 22A and the tongue 22B herein disclosed.

In FIGURES 13 and 14 a relatively thick tongue 22B is shown, which may have a width 57B which is equal to the distance between the centers 59 of the short radii of the ellipse, such as .040 inch, more or less. The tongue 22B may have a thickness just slightly less than double the short radius length of .005-.006, such as from .009-.01l inch, more or less. Such thickness has been found to be a suitable maximum for the purposes of this invention.

Such tongue 22B permits the proper play between the tongue 22B and the leaf spring 26 which has been described in connection with tongue 22A.

The sizes herein given are intended to be typical for the illustrative embodiment described.

The tongue width and thickness of the tongue at one end of the leaf spring 26 may be diiferent from the tongue width and thickness at the other end of the leaf spring 26. For example, a tongue as thin as 22A may be used at one end of the spring 26 and a tongue as thick as 22B may be used at the other end of the spring 26.

The first fulcrum member 14 may be a spring actuating member 62 which may be bent to produce the fulcrum member 14, and which may be actuated by the plunger 64. The actuated second fulcrum member 20 may be an actuated blade of spring material, which carries the movable contact buttons 66 and 68. These movable contact buttons 66 and 68 respectively contact the stationary contacts 70 and 72. The blade 20 may be connected to the external line connector 74, and the stationary contacts 70 and 72 may be connected to relatively rigid conductor bars 76 and 78, which may extend outside the casing to provide line connectors, as indicated.

This invention may also be applied to leaf spring members of the character disclosed in the Kohl patents, in which the leaf snap spring members are more or lesss rectangular in shape, such as is illustrated at 26' in FIG- URE 5 of this application. These thin elongated leaf spring members 26, of FIGURE 5 of this application, may cooperate with first fulcrum member 14' and second fulcrum member 20'. The openings 34' may be made in the same manner and embody the same principles as has been disclosed in connection with FIGURES 3, 4, 6 and 7. This is, the openings 34 may be elongated openings, which may be substantially elliptical as heretofore described, and may cooperate with the tongues 16' and 22 substantially in the same manner as the correspondingly indicated members of FIGURES 3, 4, 6 and 7.

It is believed unnecessary to repeat the detailed decription concerning FIGURE 5, which has been given concerning the illustrations of FIGURES 3, 4, 6 and 7. The arcuate shape 28, shown in FIGURES 6 and 7 is applicable also to the leaf spring 26' and all other disclosures in these FIGURES 3, 4, 6 and 7 also apply to FIGURE 5, modified only with regard to the rectangular shape of the snap spring 26. It will be readily apparent that the same principles which have been described in connection with the leaf spring of the Rhodes patent, may be used in connection with the leaf springs which have been disclosed in the Kohl patents, without further description.

In FIGURE 8, the elongated opening 34" may be substantially rectangular in form, but may be provided with relatively long radius corner arcs 80, which will remove the local stress producing sharp notches and corners which were present in the Kohl patent construction of the slots therein disclosed, and which in the Kohl construction produced stresses so that the long life of this invention could not be obtained in the Kohl construction. Likewise, in FIGURE 9, the elongated opening 34 may be substantially rectangular, or may be an opening with parallel sides. However, the ends may be arc shaped, or semicircular at 82. The radius of this semicircle 82 may be sufficiently large, so that there are no local stress producing notches and internal corners in the openings 34", to produce the rupturing effect which was produced by the previous constructions.

In the embodiment of FIGURE 10, the opening 34" may be made substantially circular, and in which the opening 34" is formed in the unbent end of the snap spring, so that it lies in a plane which is free of sharp bends. be spaced only far enough away from the circumference of the circular opening 34 to maintain the leaf spring 26 or 26 substantially aligned with the fulcrum members 14 and 20 and yet provide the necessary clearance of the tongue 16 within the opening. This embodiment may be used in switches that do not require as much accuracy in snapping point as is maintained in the other embodiments herein disclosed.

The tongue edges 35" of tongue 16 (or 22) may In connection with all of the embodiments, the previous openings in the leaf springs which were disclosed and used in connection with embodiments of the Kohl patents, and the Rhodes patent, included sharp internal corners at the notches, which produced local stresses at such corners. These sharp internal corners would produce a rupturing effect at these corners of the slots and which would cause ruptures at the slots, so that the limit of the life of the previous springs of the patents was much less than the leaf springs of this invention, as was indicated by the tests herein referred to. These were extensive tests, and were applied to many corresponding constructions in which the previous slot constructions were compared with the slot constructions according to this invention. In all of these comparative tests, the slot constructions of this invention provided the much longer spring life, as has been disclosed.

It is to be understod that the specific slot constructions herein disclosed, and the specific leaf spring constructions herein disclosed have been disclosed by way of example, and that other constructions may be used, which embody the advantages herein disclosed, and which come within the scope of the claimed subject matter of this application.

The snap spring may be made as described in the Kohl patent, 2,237,705, page 1, column 2, lines 45+, in which a metal strip of the desired width is rolled to a predetermined thickness and heat treated to give it the desired temper. Apertures are then punched in the strip at the desired distance apart in accordance with the length of the spring desired and the metal strip is then cut to provide a spring of the proper length.

The snap spring may be formed, if desired, to give it arcuate form, as described in the Kohl Patent 2,558,258, column 3, line 55 to column 4, line 6, and in Kohl, 2,558,- 219, column 4, lines 10+, to produce snap springs of rectangular shape, with apertures at the end thereof, and preformed into arcuate shape, or used flat and then given their arcuate shape when assembled in the switch. Also, the snap springs may be made as described in the Rhodes patent in which the snap spring is normally fiat until assembled, and has the shape substantially as shown in FIGURE 3 of this application.

Regardless of whether the snap spring is of rectangular form, or of the form shown in FIGURE 3, the use of the openings to receive the tongues, in accordance with this invention, increases the life of the previous construction very substantially.

The looseness of the tongue in the aperture of the snap spring may be made in accordance with well established practice of the commercial use of switches made in accordance with the Kohl patents and the Rhodes patent. The arcs which are produced at the ends of the elongated openings of this invention are sufficiently close to the edges of the tongues, so that the tongues are automatically maintained and substantially aligned between the fulcrum members. During the oscillation of this snap spring, the spring automatically aligns itself between the fulcrum members, without undue stresses being placed at the ends of the apertures.

It is thus to be seen that a new, useful and unobvious rolling spring switch construction has been provided by this invention.

While the form of the invention now preferred has been disclosed as required by the statutes, other forms may be used, all coming within the scope of the claims which follow.

What is claimed is:

1. In combination:

an actuating and first fulcrum member having a first protruding tongue and a respective leaf spring engaging edge shoulder on each side of said tongue;

a second fulcrum member having a second protruding tongue aligned with said first tongue and having a respective leaf spring engaging shoulder on each side of said second tongue;

a flexible, thin, hard metal, elongated leaf spring which is free of local stress producing sharp bends, notches and internal corners and having an arcuate main body with rocking end portions free of line fold deformation engaging respective ones of said edge shoulders with substantially straight surfaces which are extensions of said arcuate main body, said end portionseach having a respective tongue receiving oblong opening having arc shaped end portions, which opening is free of local stress producing sharp bends, notches and internal corners, said opening loosely limiting the turning movement of a respective tongue in said opening and confining the sidewise and endwise movement of said leaf spring to maintain said leaf spring substantially aligned between said fulcrum members.

2. A combination according to claim 1, in which both of said respective tongue receiving openings are substantially elliptical in shape.

3. A combination according to claim 2 in which said respective tongue receiving openings have opposite short radius circle arcs merged with opposite long radius circle arcs and the widths of said tongues are encompassed by said long radius circle arcs.

4. A combination according to claim 3, in which the thicknesses of said tongues are less than double the lengths of the radii of said short circle arcs.

5. A combination according to claim 4 in which the ends of said substantially elliptical opening provide sufficient clearance for the metal thickness of said tongues.

6. A combination according to claim 1, in which one of said respective tongue receiving openings is an opening which is substantially rectangular in shape with rounded corners and free of local stress producing internal corners.

7. A combination according to claim 6 in which the rounded corners provide sufiicient clearance for the tongue thickness.

8. A combination according to claim 1 in which one of said respective tongue receiving openings which has substantially parallel sides and arc shaped ends.

9. A combination according to claim 8 in which said are shaped ends are semicircular.

It A combination according to claim 8 in which said are shaped ends provide sufiicient clearance for the tongue thickness.

References Cited by the Examiner UNITED STATES PATENTS 2,816,195 12/1957 Holmes. 2,927,171 3/1960 Rhodes.

ROBERT K. SCHAEFER, Primary Examiner.

D. SMITH, JR., Assistant Examiner.

Claims (1)

1. IN COMBINATION: AN ACTUATING AND FIRST FULCRUM MEMBER HAVING A FIRST PROTRUDING TONGUE AND A RESPECTIVELY LEAF SPRING ENGAGING EDGE SHOULDER ON EACH SIDE OF SAID TONGUE; A SECOND FULCRUM MEMBER HAVING A SECOND PROTRUDING TONGUE ALIGNED WITH SAID FIRST TONGUE AND HAVING A RESPECTIVE LEAF SPRING ENGAGING SHOULDER ON EACH SIDE OF SAID SECOND TONGUE; A FLEXIBLE, THIN, HARD METAL, ELONGATED LEAF SPRING WHICH IS FREE OF LOCAL STRESS PRODUCING SHARP BENDS, NOTCHES AN INTERNAL CORNERS AND HAVING AN ARCUATE MAIN BODY WITH ROCKING END PORTIONS FREE OF LINE FOLD DEFORMATION ENGAGING RESPECTIVE ONES OF SAID EDGE SHOULDERS WITH SUBSTANTIALLY STRAIGHT SURFACES WHICH ARE EXTENSIONS OF SAID ARCUATE MAIN BODY, SAID END PORTIONS EACH HAVING A RESPECTIVE TONGUE RECEIVING OBLONG OPENING HAVING ARC SHAPED END PORTIONS, WHICH OPENING IS FREE OF LOCAL STRESS PRODUCING SHARP BENDS, NOTCHES AND INTERNAL CORNERS, SAID OPENING LOOSELY LIMITING THE TURNING MOVEMENT OF A RESPECTIVE TONGUE IN SAID OPENING AND CONFINING THE SIDEWISE AND ENDWISE MOVEMENT OF SAID LEAF SPRING TO MAINTAIN SAID LEAF SPRING SUBSTANTIALLY ALIGNED BETWEEN SAID FULCRUM MEMBERS.

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