US3632921A

US3632921A - Snap action construction

Info

Publication number: US3632921A
Application number: US3599A
Authority: US
Inventors: Tbeodore Y Korsgren
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-01-19
Filing date: 1970-01-19
Publication date: 1972-01-04
Anticipated expiration: 1989-01-04
Also published as: CA935667A; GB1315586A; FR2075729A5; DE2102218A1

Abstract

A snap blade construction comprising a generally rectangular flat blade having side strips interconnected at each end. Extending inwardly from the side strips are projections or fulcrums. A self-retaining post member is inserted between the projections to stress the blade so that it will assume either one of two stable states and will move with a snap action between the two states.

Description

United States Patent Inventor Theodore Y. Korsgren 464 Taulman Road, Orange, Conn. 06477 Appl. No. 3,599 Filed Jan. 19, 1970 Patented Jan. 4, 1972 SNAP ACTION CONSTRUCTION 21 Claims, 17 Drawing Figs.

U.S. Cl. 200/76, 200/67 D Int. Cl H0lh 15/18 Field of Search 200/67 D, 76; 74/100 P References Cited UNITED STATES PATENTS 7/1949 Martin 200/76 2,608,628 8/1952 Dietrich 200/76 2,624,819 1/1953 Spina et al. 200/67 D UX 2,734,959 2/ 1956 Immel 200/67 D UX 3,061,694 10/1962 Carlson 200/67 D UX 3,449,534 6/1969 Bauer 200/67 D UX FOREIGN PATENTS 450,521 4/ 1968 Switzerland 200/67 D UX Primary Examiner-David Smith, Jr. Attorney-Delia and Montgomery ABSTRACT: A snap blade construction comprising a generally rectangular flat blade having side strips interconnected at each end. Extending inwardly from the side strips are projections or fulcrums. A self-retaining post member is inserted between the projections to stress the blade so that it will assume either one of two stable states and will move with a snap action between the two states.

, I 0 39 T 4 "I'm 36 m 35 INVENTOF? Weed on: Y. Kovsqren PATENTED JAN 4 m2 SHEET 2 BF l Theo dare Kovsqvan Dex o W9 wwm PATENTEU JAN A I972 EHEET W []F Q m GE wwnw 0 K W o w 6 m ATTORNEYS W W W M m w SNAP ACTION CONSTRUCTION This invention relates to snap blade constructions.

The invention is particularly useful in the art of snap action electrical switches and, accordingly, will be disclosed in preferred embodiments in such environments. The prior art is replete with various designs of snap action switches, sometimes referred to as grass hopper switches which generally comprise a switch blade of substantially rectangular outline which is stressed longitudinally of the major dimension thereof and the switch is provided with some central actuating member such that when the actuating member is moved transversely to the blade and the ends of the blade are retained, the blade will snap from one direction of concavity to the opposite.

These devices have found wide use in various types of switching environments requiring a snap action. However, the blades have limitations that when actuated both ends thereof do not necessarily travel parallel and a cocking action between the extremities of the blade could occur. This possibility decreases the degree or probability of stability of such switches. The presently known switches of this general type also present some problem in assembly in that the blade and the actuating member are not mutually self-retaining when not in the housing.

Accordingly, the present invention is intended to overcome the limitations of these known switches and provide a stable snap switch having a pair of contact ends which may be symmetrically located with respect to an actuating member, may be asymmetrically located with respect to an actuating member to provide greater movement of one switch end with respect to the other, and may further be so arranged that the normal actuating member is held stationary and one end of the blade is snapped through actuation of the other end.

These results are achieved by providing a snap blade of generally rectangular outline to provide generally parallel arms tenninating at either end thereof in contact portions. In a normal symmetrical design where it would be used as a double-break switch an actuating member is mounted to the blade member in such a manner that the arms of the blade are stressed both in tension and in torsion. This stresses the switch blade such that in the construction described one end always moves symmetrically with the other and the blade will snap from one degree of concavity to another. Moreover, the construction is such that the actuator-to-blade construction is always selflretaining.

Accordingly, an object of this invention is to provide a new and improved snap blade construction.

Another object of this invention is to provide a new and improved snap blade construction of improved stability.

A further object of this invention is to provide a new and improved snap blade construction utilizing a blade which is stressed both in tension and in torsion to provide increased stability of operation.

A still further object of the invention is to provide new and improved snap acting switches and an improved method of making the same.

The features of the invention which are believed to be novel are particularly set forth and distinctly claimed in the concluding portion of this specification.

However, the invention both as to its organization and operation, together with further objects and advantages thereto, may best be appreciated by reference to the following detailed description taken in conjunction with the drawings, wherein:

FIG. 1 is a plan view of a blade construction embodying the invention;

FIG. 2 is a plan view of the blade of FIG. 1 with an actuating member assembled thereto;

FIG. 3 is a view seen in the plane of lines 3-3 of FIG. 2;

FIG. 4 is an end view of the assembly of FIG. 2 showing the blade in one stable condition;

FIG. 5 is an endview of the blade of FIG. 2 showing the blade in another stable condition;

FIG. 6 is an isometric exploded view, diagrammatically setting forth a switch construction embodying the invention;

FIGS. 7 and 8 are diagrammatic views of the switch blade of FIGS. 2 and 6 in a double-make, double-break arrangement in various stages of operation;

FIG. 9 is a perspective view partially in section of another snap action switch embodying the invention;

FIG. 10 is a view in section of still another snap action switch embodying the invention;

FIG. I] is a view seen in the plane: of lines 11-11 of FIG. 10;

FIG. 12 is a half section view through still another switch mechanism embodying the invention;

FIG. 13 is a bottom view of still another switch mechanism embodying the invention;

FIG. 14 is a view seen in the plane of lines 14-14 of FIG. 13, and

FIG. 15 is a view seen in the plane of lines 15-15 of FIG. 14.

FIG. 16 is a sectional view of a portion of a switch housing embodying the invention; and

FIG. 17 is a view seen in the plane of lines 17-17 of FIG. 16.

A snap blade embodying the invention in one form thereof is generally indicated by the reference numeral 10 and is of generally rectangular shape having spaced apart side strips or

margins

11 and 12 which are further defined as spaced apart pairs of

arms

11a, 11b, 12a, 12b and joined at either end by

end portions

13 and 14, respectively. Projecting from the margins towards each other intermediate of the ends are projections 15 having edges 16 spaced apart. a distance D when the blade 10 is in the relaxed position. Edges 16 may be relieved by cutouts 17 (shown in broken line) to define a substantially circular aperture. This permits the use of a tapered screw (not shown) to spread the arms 15 apart.

The blade 10 as shown in FIG. 1 is formed from a flat piece of metallic material and is so shaped that the

margins

11 and 12 are slightly bowed with elbows 18 in the medial portions thereof in the area of the projections 15. Blades utilized in the invention are one-piece structures which may be stamped, etched or otherwise formed from a flat flexible metallic sheet.

The blade 10 is assembled to a member which is hereinafter referred to as a post or spreader 19. The post may be utilized as, an actuating member when the assembly is used in one application and may also be utilized as an anchoring member in other applications. As shown more clearly in FIG. 3, the post is formed with indentations or notches 20 on opposite sides thereof which receive a portion of projection 15 and the edges 16 of projections 15 are preferably received on a flat 21 at the bottom of notch 20. The notch 20 is further defined by walls 22 and 23 which act to retain the projections 15 and further act to define the limits of motion. It has been determined that an angular relationship of approximately 30 degrees between the walls 22 and 23 is preferable. Alternatively, the bottom 21 of the notch could be formed in any manner as, for example, on a radius to be complimentary to the shape of the edge 16 of projection 15. The bottoms of the notches 20 are dimensioned so as to cause the arms and more precisely the edges 16 of projections 15 to spread apart to a distance d,. This produces a spreading action on side strips or

margins

11 and 12 which tends to increase the effective length L of each arm portion on either side of the projections 15 while each of the arm portions are restrained at their outer ends by the

end pieces

13 and 14. This spreading action further introduces a torsional stress in blade member 10. In the construction shown in FIG. 2 all of the arm portions are equal in length L and therefore the torsional stress in all four arm portions is equal.

This stressing causes a dishing of blade 10 as more clearly exemplified in FIGS. 4 and 5. The post 19 may be initially inserted by bending the strips or

margins

11 and 12 so as to move the edges 16 of projections 15 out of a coplanar relationship, then sliding the post member 19 therebetween until the projections 15 are received in the notches 20.

This construction permits the blade to be self-retaining in the post under all conditions and greatly enhances the assembly of the snap blade assembly into a housing. This selfretaining preassembly substantially reduces overall assembly time of a complete switch as shown in FIG. 6.

An embodiment of the invention in a so-called doublemake, double-break switch is shown in FIG. 6. The switch 30, as diagrammatically illustrated in FIG. 6, comprises a generally cylindrical housing 30a having

end walls

31 and 32. The end walls carry upper

terminal members

33 and 34 and lower

terminal members

35 and 36 which are shown as generally L-shaped and having

contacts

37, 38, 39 and 40 thereon adapted to be contacted by

contact pieces

41 and 42 carried by the blade 10. Defined in bottom wall 32 is a passage 43 adapted to act as a guide for an actuating plunger 43a. Extending downwardly from upper wall 31 is a spring guide 44 adapted to locate and retain a spring 45. Spring 45 is adapted to engage a seat 46 on a post 19. Actuator 19 at its upper end may be formed in any suitable manner as shown by the seat 46 and extension 47 to receive spring 45. Spring 45 functions toact as a return, as will hereinafter be described.

Each of the

terminal members

33, 34, 35 and 36 has a leg 49 adapted to extend through a slot 50 in one of the end walls and be supported therein in operative spaced relation to the upper terminal. It will be understood that other structures for locking the terminal members to the housing may be utilized. However, precise definitions of structure of switch housings are well known to those skilled in the art and are not required for a disclosure of the invention in this instance.

As shown in FIG. 6, the blade is in the position it would assume when it is in contact with

terminals

37 and 38 under the bias of spring 45.

When the operator or a sensing device acting upon post 19 as, for example, rod 43a moves upwardly against the bias of spring 45,

contact pieces

41 and 42 engage

contacts

37 and 38 as shown more clearly in FIG. 7 and movement of post 19 will then cause the projections which act as a fulcrum to snap over center to the position illustrated in FIG. 5. The blade thus snaps from the position shown in FIG. 4 to that shown in FIG. 5. At this

time contacts

41 and 42 will be snapped over to

terminals

39 and 40, respectively. When the force on rod 43a is removed, the energy stored in spring 45 will move post 19 downwardly as exemplified in FIG. 8. The

contacts

41 and 42 now engaging

terminals

39 and 40 are limited in movement. Upon further movement of post 19 under the bias of spring 45,

the blade will snap back from the condition shown in FIG. 8 to the condition shown in FIG. 4.

In this manner, the blade 10 snaps between its operating position when the end portions thereof are restrained from movement in one direction and the post 19 is moved in that direction a predetermined distance to snap over center the projections 15.

The stressed blade as thus far disclosed has only two conditions of stability, and must assume one of those two conditions due to the stresses in the arms and the interconnection thereof. The two ends of the blade must always be snapped in the same direction due to the stressing of the arms in both tension and torsion. There will be no cocking of the blade upon movement thereof from one operating position to another.

The blade 10 is, of course, of a conductive material and as illustrated in FIG. 6 is adapted to complete an electrical circuit between

contacts

37 and 38 or

contacts

39 and 40. The positive bi-stability of the switch blade assures that there will be no cocking and resultant crosscircuiting as by contacting

terminals

33 and 36 or 35 and 34.

The invention thus far has been illustrated in conjunction with a double-make, double-break switch adapted to make one of two circuits. It is apparent that one of the set of

terminals

33, 34 or 35, 36 could be eliminated an electrical conductors and some sort of stopping surface or abutment substituted therefor. For example, if the

terminals

37 and 38 were eliminated, or if no electrical connections were made thereto, the blade 10 under the influence of spring 45 would be in a normally closed position when the circuit made thereby could be interrupted by the occurrence of some condition which actuated rod 43a to open the circuit. For example, this type of application might be used in circuits with electric lights which is designed to be illuminated when a door was opened. For use in an application such as a starting circuit, the

terminals

39 and 40 might be eliminated or not connected to an external circuit. Then, upon application of a force to rod 43a the blade 10 would complete a circuit between

terminals

37 and 38 so long as the necessary pressure was exerted on post 19 through rod 43 a.

The invention may also be embodied in other snap acting applications, and where the post 19 is stationary and an actuating force is applied to one end of the blade.

In FIG. 9, a switch assembly comprising a blade 60 as shown in FIG. 1 is mounted to a post6l as shown in FIG. 2, which post is an extension of a terminal 62.

Terminals

63 and 64 are carried in a housing 65 of insulating material having a cover portion 66.

Terminals

63 and 64 have contact portions 69 and 70, respectively, disposed in spaced apart relation on either side of end 71 of blade 60. Mounted to blade 60 at end 71 is a contact 72. Disposed about a projection 73 on surface 74 is a spring 75, which through a spring end plate 76 acts on end 77 of blade 60. Spring 75 acts to urge blade 60 to this position shown.

An actuating button or plunger 78 extends through cover 66 and when depressed exerts a force on end 77 of blade 60 against the bias of spring 75. When plunger 78 is depressed, end 77 is forced downwardly against spring 75 while blade 60 is restrained at post 61. As the stresses in blade 60 are reversed, it snaps to its other stable state and contact 72 will engage contact portion 70. When the force is released from plunger 78, spring 75 will snap blade 60 back to the position shown.

In the assembly of FIG. 9 the distance of the

ends

71, 77 of the blade are asymmetrical with respect to post 61. Thus when an actuating force is applied to the shorter end, as shown, a magnified or amplified movement is obtained at the other end.

The spring 75, and also the spring 45 (FIG. 6) may be eliminated if the blades are given a permanent set in one degree of concavity. This may be accomplished by initially inserting a spreading device as shown in FIG. 2, and then heat treating the blade to impart the permanent set in one degree of concavity. Such blades will always return to the permanent set condition when an actuating force is removed. Accordingly, such a blade would be considered to be monostable.

An embodiment of the invention wherein the blade is preformed is shown in FIGS. 10 and 11. A switch 79 comprises a housing member 80 having a cover 81.

Terminal members

82, 83 and 84 are mounted in housing member 80. Terminal 82 has formed thereon a post 85 to which is mounted a blade 86 in a manner hereinbefore described. One end of blade 86 which carries a contact button 87 is adapted to make contact between either one of

terminals

83 or 84. The other end of blade 86 which may or may not carry a button 88 is captured between an abutment 89 on housing 80 and an abutment member 90 affixed to housing 80.

Blade 86 has been formed and mounted to post 85 and thereafter heat treated to impart a permanent set thereto as exemplified in FIG. 10. Alternatively, the blade might be heat treated on a first post and then transferred to post 85. The degree of prestressing will depend on the dimension by which the blade is spread during the heat treating operation. An actuating member 91 has projections 92 arranged to engage blade 86 on the margins or strip portion thereof at projections 93. Downward motion of actuating member 91 through actuation of button 94 will cause the blade to snap over to the position shown in broken line in FIG. 11. When the actuating force is released the preformed blade will snap back to the position shown in full line in FIGS. 10 and 11.

FIG. 12 shows another embodiment of the invention in cross section wherein the blade may be allowed to remain in either one of its two stable states. Blade 96 is mounted to a post 97 which may be a terminal member as shown in FIGS. 9 and 10. An actuating member 98 is formed to define pockets 99 which receive the outer edges of the side strips or margins of blade 96 adjacent the projections. Member 98 is provided with a recess 98a which slidably receives post 97. Connected to actuating member 98 is a button headed plunger 100 which permits the blade 96 to be pushed to one stable position or pulled to the other. The overall housing 101 and cover plate 102 may be otherwise formed as shown in FIG. 10, and also may be utilized as a double-make, double-break arrangement to provide connection from a center terminal to outer terminals.

Reference is now made to FIGS. 1 and 2 and in particular FIG. 2. FIG. 2 shows in broken line the areas of stress in the blade at its midpoint as it snaps from one position to the other. The areas indicated by T generally represent tension, the areas indicated by C generally indicate areas of compression and the areas marked S generally indicate areas of shear. It will be ap parent that with these stress distributions through the blade, the blade is in a very unstable condition and dependent on the direction of motion of the post, will snap from one of its stable positions to the other.

To minimize this stress concentration, the degree of curvature, or radii R and R are made large to decrease the stress concentrations which would be present about small radii or degrees of curvature. The radius R and indentation behind the projections serve an additional purpose in increasing or extending the working length L in the

arms

11a, 11b, 12a, 12b without increasing the overall length of the blade. This further permits the edges 16 of projections 15 to be elongated for additional stability when mounted to post 19. The degree of permissible stress concentrations at any point will depend on the application, size and material of blade, etc., and the blade may be shaped accordingly dependent on these parameters.

To overcome any adverse effects which may be due to the stress concentrations in the blade, a resilient post which will provide some stress relief as the blade snaps over may be utilized. An embodiment of the invention utilizing such a post is shown in FIGS. 13-15. The switch mechanism of FIGS. 13-15 may comprise a housing 104 of generally cylindrical shape having a bottom closure wall 105 which receives therethrough an actuator and post carrying member 106. A post 106a, as more clearly shown in FIG. 15, is formed of a resilient springy material to provide notches 107 for the projections 108 of blade 109. Post 106a is carried in a recess 110 in actuator 106. The actuator and carrier 106a has upstanding portions 110a which extend through blade 109 and receive thereupon a spring seat 111. Spring seat 111 is formed with a passage 112 designed to receive an upstanding portion 113 of post 106a. The mechanism further includes

terminal members

114 and 115 having contact portions 116 and 117, respectively, which are normally contacted by contact buttons 118 and 119, respectively, on the ends of blade 109. A spring 120 bears on seat 111 and at its upper end receives another seat 121. The blade 109 is normally in the position shown in FIG. 14 to complete a circuit between

terminals

115 and 116. However, if the post carrier and actuator 1060 is moved upwardly against the bias of spring 120, the upward movement of post 106a will cause blade 109 to snap through and the terminal buttons 118 and 119 to engage the projections 122 which may not have any electrical significance or may be electrical terminals (not shown). When the actuating force is removed from member 106, spring seat 111 under the bias of spring 120 and bearing on the projections 11011, 111 and/or shoulders 123 of post 106a will cause post 106a to move downwardly and cause the blade 109 to again snap through to the position shown in FIG. 14.

The post carrier and actuator 106 is designed to prevent any rotational movement of post 1060. The actuator 106 may have a tongue 124 thereon adapted to slidably be received in groove 125 in bottom wall member 105.

The resiliency of post 106a will permit it to be compressed at notches 107 as the blade 109 moves through its unstable position as exemplified in FIG. 2. This decreases the stress concentrations in the blade and will offer longer blade life. As the blade snaps through its center point, the resilience of post 106 will expand post 106 at notches 107 and aid in the snap action.

Another mechanism embodying the invention is shown in FIGS. 16 and 17. The mechanism of FIGS. 16 and 17 is the same as that of FIG. 14 except as otherwise shown. A housing 128 has a bottom wall 129 having an aperture 130 which receives an actuating member 131 therethrough. Member 131 has a recess or well 131a defined therein conforming to the cross-sectional dimensions of a post 132 and receiving one end of the post snugly therein. A snap blade 133 is mounted to post 132 as previously described. Carried on the upper end of post 132 is a cap-shaped member 134 providing a spring seat on a flange 135 upon which a return spring 136 is seated. Seat 134 defines a recess or well 137 shaped to conform to the cross-sectional dimensions of post 132. This provides a substantially rigid connection between post 132, actuator I31, and member 134 to prevent relative rotation or cocking between the members. Actuator 131 is maintained in predetermined position with respect to housing 128 by one or more torques 138 on member 131 received in grooves 139 in bottom wall 129.

The blade 133 will snap to its other stable position when a predetermined force is exerted on actuator 131. When the force is released, spring 136 acting upon member 134 will urge post 132 downwardly and blade 1133 will snap back to its original position.

In constructing the invention the blade is formed by one of the techniques that have previously been described. Suitable materials are No. 25 Beryllium copper and l77 Ph stainless steel, as well as spring materials known as Havar and Elgilloy, having a relatively high Cobalt content. The formed blade is then heat treated. In the case of l7-7 Condition C stainless steel, it may be heat treated for one hour at about 900 F. Where it is desired to preform the blade for a monostable construction, it is heat treated while mounted to a post.

By way of example only, blades having an overall length of 0.650 inches and a width of 0. l 85 inch have been constructed at a thickness of 0.004 and 0.006 inches in stainless steel and Beryllium copper. The dimension D, was 0.0l0 inches and dimension D varied to 0.035 inch giving a spreading ratio of up to 3.5 to l. The length of the edges 16 were 0.110 inch. This is substantially greater than the dimensions D and D which contributes to greater stability.

The foregoing dimensions are for illustrative purposes only to exemplify relative dimensioning of a blade constructed in accordance with the invention. The dimensions of any particular blade and its post will be determined by the specifications of the environment in which it is to work and the functions it must accomplish.

The posts or spreaders are preferably formed of four-sided stock with the notches defined in opposed sides. However, any post construction which may be mounted to the blade in a stable arrangement may be utilized. For example, a double lead tapered screw may be inserted into a cutout 17, FIG. 1, to obtain the desired degree of stressing of the blade.

While various embodiments of the invention showing appli' cations of the invention have been disclosed, it is to be understood that the switching construction embodying any of the features of the invention shown may be combined for a given application. The versatility of this switch blade construction is exemplified by the fact that the blade may be used in a sym metrical design merely as a circuit-breaking device with the post movable or stationary or in a double-make, double-break device, again with the post either movable by an actuating member or the post stationary and the actuating force applied to the blade.

Still further, the blade may be used in an asymmetrical design where one arm is longer than the other and additionally the post member may be conductive and form a portion of a terminal connector or be electrically connected to a terminal connector.

The invention is not limited to electrical applications. It may be used in control systems operating on pneumatic, fluidic and hydraulic principles. Fluid forces may be applied to the blade or post to achieve the desired result in the same manner that mechanical forces are applied.

It may thus be seen that the objects of the invention set forth as well as those made apparent from the preceding description are efficiently attained. Inasmuch as other embodiments of the invention may occur to others skilled in the art, the appended claims are intended to cover all modifications of the disclosed embodiments of the invention as well as other embodiments thereof which do not depart from the spirit and scope of the invention.

What is claimed is:

l. A snap action blade assembly comprising a generally flat blade member having spaced apart side strips joined at each end by end portions said strips being substantially longer than said end portions, said side strips having a dimension transverse to the length thereof substantially greater than the thickness of said blade, said strips having facing edges spaced apart a predetermined distance, a member having a dimension greater than said predetermined distance disposed between said strips and engaging said edges and spreading said strips apart transverse to the length thereof so as to tend to lengthen said strips and produce a torsional stress in said strips to produce concavity in one side of said blade.

2. The blade assembly of claim 1 wherein said strips include inwardly directed projections extending toward each other intermediate the ends of said strips, said projections defining said edges.

3. The blade assembly of claim 2 wherein said member is provided with notches on opposite sides thereof, said notches receiving said edges of said projections therein.

4. The assembly of claim 3 wherein said notches are defined in said member with a generally V-shape with the bottom of said notch being sized and shaped to be essentially complimentary to the edge of the projection received therein.

5. The assembly of claim 2 wherein said projections have essentially parallel spaced apart edges, the length of said edges contacting said member being substantially greater than said predetermined distance between the said edges.

6. The assembly of claim 3 wherein the walls defining said notches are angularly disposed at approximately thirty degrees.

7. The assembly of claim 2 wherein said projections have parallel spaced apart edges.

8. The assembly of claim 7 wherein said projections are relieved between said edges thereof and the area where said projections join said strips.

9. The assembly of claim 3 wherein said spreading member is formed of a resilient material, so that said spreading member may elastically deform as said blade snaps between positions.

10. A snap blade construction comprising a housing means, a snap blade carried by said housing means and having opposed end portions, said blade having two substantially longitudinally disposed side strips spaced from each other and integrally joined at each adjacent pair of ends thereof respectively to said end portions said side strips being substantially longer than said end portions, said side strips each having projections directed toward each other and defining facing edges spaced apart a predetermined distance, and a post member having a dimension greater than said predetermined distance disposed between said projections and bearing on the edges thereof to spread apart the projections and torsionally stress said side strips and produce concavity in one side of said blade, and means for applying an actuating force to one of said post member and said blade, whereby said blade will snap between opposed positions of concavity relative to said housing means as said actuating force moves said blade or said post member relative to said housing means.

11. The construction of claim 10 wherein said post is stationary with respect to said housing and said blade is snapped by afplication of a force to one end thereof.

l The construction of claim 10 wherein said post is stationary with respect to said housing and said blade is snapped by application of a force to said projections.

13. The constructions of claim 10 wherein said post is movable along its length, said housing member includes spaced apart abutments disposed on either side of the ends of said blade, and said blade is snapped by application of a force to said post.

14. The construction of claim 13 further including a spring carried by said housing and acting on said post so that said spring has energy stored therein when said switch is snapped by a force on said post and said spring will resnap said blade when the force on said post is released.

15. A snap blade construction as set forth in claim 10 wherein said side strips of said blade are substantially parallel to each other before said blade is assembled to said actuator member.

16. A snap blade construction as set forth in claim 15 wherein said projections extend from the medial portion of said side strips, said projections define parallel spaced apart edges, and the dimensional length of said edges are substantially greater than the dimension between said edges.

17. A snap blade construction as set forth in claim 14 wherein said projections define arms between said projections and said end portions on each of said strips and said projections are relieved between said edges and said strips to lengthen the effective length of said arms.

18. A snap blade construction as set forth in claim 10 wherein said side strips of said blade each has a bowed planar configuration with the elbow thereof being substantially medially disposed and facing the elbow of the other side strip before said blade is assembled to said actuator member.

19. A snap blade construction as set forth in claim 10 wherein said post has a substantially rectangular transverse cross-sectional configuration defined by four flat sides thereof, grooves being provided in opposed flat sides of said actuator member for receiving the edges of said projections, said projections having straight free edges received in said grooves.

20. The construction of claim 10 wherein said post is resilient between the lines of contact of said projections thereon.

21. The construction of claim 10 wherein said blade is electrically conductive and adapted to make and break electrical contacts. I

Claims

1. A snap action blade assembly comprising a generally flat blade member having spaced apart side strips joined at each end by end portions, said strips being substantially longer than said end portions, said side strips having a dimension transverse to the length thereof substantially greater than the thickness of said blade, said strips having facing edges spaced apart a predetermined distance, a member having a dimension greater than said predetermined distance disposed between said strips and engaging said edges and spreading said strips apart transverse to the length thereof so as to tend to lengthen said strips and produce a torsional stress in said strips to produce concavity in one side of said blade.

11. The construction of claim 10 wherein said post is stationary with respect to said housing and said blade is snapped by application of a force to one end thereof.

12. The construction of claim 10 wherein said post is stationary with respect to said housing and said blade is snapped by application of a force to said projections.

21. The construction of claim 10 wherein said blade is electrically conductive and adapted to make and break electrical contacts.