US3051802A

US3051802A - Simplified snap-action contact switch

Info

Publication number: US3051802A
Application number: US64412A
Authority: US
Inventors: Hugh E Riordan
Original assignee: General Precision Inc
Current assignee: General Precision Inc
Priority date: 1960-10-24
Filing date: 1960-10-24
Publication date: 1962-08-28
Anticipated expiration: 1979-08-28

Description

Aug. 28, 1962 H. E. RIOR DAN SIMPLIFIED SNAP-ACTION CONTACT SWITCH Filed Oct. 24, 1960 r QQ 3,51,8d2 Patented Aug. 28, 1962 ambu- 3 051 802 SlTvRLlFaIEl) SNAP-AQZTEON CONTACT SWITCH Hugh Riordan, Wycltolf, Ni, assignor to General Precision Inc, Little Falls, NJ, a corporation of Delaware Filed Oct. 24, 1960, Ser. No. 64,412 8 Claims. (Cl. 20(367) This invention relates to electrical contact switches; more particularly, to a simple snap-action positive-locking contact switch whose parameters may easily be adjusted.

In many applications of electrical contact switches, such as in missiles and aircraft, it is required that the switch be insensitive to vibration and shock or acceleration, both to the switch itself and to vibratory components in the actuating force. This is especially necessary where the actuating force of the switch is desired to be very small. Vibration of the switch and vibratory components in the actuating force cause chatter between the movable contact and the fixed contact resulting in deleterious arcing. Shock or acceleration causes the contacts to separate, likewise resulting in arcing and sparking. The deposits formed by such arcing greatly diminish the life of the switch and make it unreliable.

Furthermore, accurate switches which can be actuated by small forces must incorporate some adjusting means whereby the actuating force necessary may be precisely set after assembly, or else the manufacture of the switch must suifer the consequential evils of close tolerances and more skillful assembly.

Attempts to construct such switches have resulted in complicated and expensive devices having fixed operational parameters. Once a switch was assembled, it was impossible to reduce or increase the minimum force necessary to actuate the switch. Moreover, while the switches overcame the effects of the vibration, they still remained inherently sensitive to shock or acceleration.

Briefly stated, in accordance with one aspect of the invention, there is provided a single movable element, one portion of which serves as the actuating member and another portion of which serves as the contact carrying and locking element. This movable element is constructed such that it is insensitive to acceleration and is positively locked against any motion which might be caused by vibrations or vibratory components in the actuating force. Also provided are simple means by which the operational parameters of the switch can readily and easily be adjusted.

It is therefore an object of this invention to provide a simple, light weight, snap-acting contact switch, which is insensitive to vibration or to vibratory components of the actuating force or to acceleration.

A further object of this invention is the provision of a snap-acting contact switch whose operational parameters can easily and readily be adjusted.-

The exact nature of this invention as well as other objects and advantages thereof will be readily apparent from consideration of the following specification relating to the annexed drawing in which:

FIGURE 1 is a plan view of a preferred embodiment of the invention showing the switch in its closed position;

FIGURE 2 is a side elevation of the preferred embodiment showing particularly, the adjusting screws;

FIGURE 3 is a frontal sectional view of the preferred embodiment showing the contacts and contact supports taken through line 33 in FIGURE 1;

FIGURE 4 is a view of the movable members in its unassembled form; and

FIGURE 5 is a plan view of another embodiment of the invention.

Generally speaking, the present invention contemplates an electrical contact switch comprising a base, having resilient spring support means and fixed contact means mounted thereon, said support means having an aperture therethrough, a notched spring disposed with its length partially contained within the aperture, the contained length being longer than the length of the aperture, contact means located along the contained portion of the spring and operationally disposed with the fixed contact means, and adjusting means by which to adjust the length of the containing aperture.

Referring now to the drawings there is illustrated a preferred embodiment 10 comprising five primary parts; a base, a resilient spring support, spring means, a fixed contact support and adjusting means.

The base can assume any appropriate shape. In the embodiment shown, it is a rectangular solid 12 composed of some electrical non-conducting material, such as a phenolic resin or the like.

The spring support shown is a ribbon 13 of resilient electrical conducting material, e.g., beryllium copper, steel, etc., with its ends 14- and 15 bent at right angles to its midsection 16. Located centrally in the mid-section 16 of the spring support 13, is aperture 17, having two

sharp vertices

18 and 19 as a part thereof. The spring support is affixed to the base 12 using

ends

14 and 15 as supports, the ends being preferably imbedded in the base, such that the mid-section 16 of spring support 13 is spaced from base 12 and parallel to it. One of the ends 15 of spring support 13 extends through base 12, so that the over-extension may be used as an electrical terminal as hereinafter disclosed.

The spring means shown, is a thin fiat strip 20 of a resilient electrical conducting material, such as that used in the construction of spring support 13, having a notch 21 at one end and a cut out 22 along one of its edges, the cutout 22 having a V-shaped portion 23. The vertices 24- and 25 of V-shaped portion 23 of cutout 22 and of notch 21 are inverted with respect to each other and lie along a line 26 parallel to the edge of the spring 20. End 27 of spring 20 takes on a curved shape such that the width of spring 20 remains relatively constant over its complete length up until taper 28, the center line 26 of the taper being the same line upon which

vertices

24 and 25 are located.

As assembled spring 20 is supported by spring support 13 with

vertices

24 and 25

abutting vertices

18 and 19. In this manner, spring 20 takes on a bowed configuration since the length of spring 20 between

vertices

24 and 25 is purposely made greater than the distance between

vertices

18 and 19 of spring support 13. In its bowed position, the curved plane of spring 20 is substantially perpendicular to the plane of mid-section 16 of spring support 13.

The fixed support, in the preferred embodiment shown, is a strip 49 of electrical conducting material, having a stepped shape and being rigidly aflixed to the base 12 by means of screws or rivets 30.

In its assembled position, one end 31 of fixed contact support 29 extends through base 12, the extension serving as an electrical terminal as hereinafter disclosed. The other step of fixed contact 29 reaches over spring support 13 and bends down through aperture 17, terminating before it reaches the upper surface of base 12. Over its whole length, fixed contact support 29 touches nothing except the non-conducting base 12 and the rivet 31 therethrough.

In the embodiment shown, the adjusting means comprise screws 32 which pass through holes 33 in spring support 13 (the holes having a larger diameter than the body diameter of screws 32) and thread into locking nuts 34 embedded in base 12.

Located on surface 35 of fixed contact support 29 on surface 36 of spring 20, which surfaces face each other, are electrical contact means, such as contact members or

discs

37 and 38, the discs being cooperatively disposed so as to abut each other when the contained portion of spring 20 assumes its bowed position toward fixed contactsupport 29. The

contact discs

37 and 38 are composed of an appropriate contact material, such as gold, silver, platinum, or the like afiixed in any way which will allow for electrical conduction through the discs to their respective supports, such as welding, soldering or the like.

By soldering small droplets of solder or by afiixing, welding or glueing small weights to end 27, the spring 20 is balanced such that its center of gravity is located substantially at vertex 25. Since spring 2t] is restrained against any motion except rotation around vertex 24, the static balancing of spring 24 as hereinbefore described results in the fact that the motion of the spring is insensitive to accelerations in any direction, and, since the spring is the only movable element of the switch, the switch itself is inherently insensitive to acceleration or shock.

In operation, the switch is actuated by a force F applied at end 27 of spring 20 somewhere substantially along the centerline 26 of taper 28. This causes a bending moment in end 27 which is transmitted through Vertex 18 to that portion of the spring 20 which is contained between

vertices

18 and 19 of spring support 13. It should be noted here that the contained portion originally has a bending moment impressed upon it due to the fact that it is longer than the aperture in which it is contained. The actuating force F rotates end 27 about vertex 18 continually building a larger moment about that point. Consequently, the contained portion of spring 20 experiences a larger moment opposite in direction to its originally impressed moment. At the instant when the actuating moment becomes greater than the original moment, the contained portion of the spring suddenly snaps out of its original bowed configuration and into its mirrorimage bowed configuration. Depending on its original configuration, this motion either makes or breaks the electrical contact between

contact discs

37 and 38, since these discs, as previously disclosed, are cooperatively disposed to abut or disengage when the spring so moves. It is to be noted that the original bending moment impressed on the contained portion of spring 20 and its consequent locking of that portion of the spring in its original position prevents any unwarranted fiexure of the contained portion. Thus the contacts are restrained from opening and closing due to vibration of the switch or to vibratory components in the actuating force.

As can readily be seen, the switch in its closed position allows current to flow between terminal end 31 of fixed contact supports 29 and end; of spring support 13, assuming there is a voltage gradient impressed therebetween, by presenting a solid conducting path through fixed support 29, through contact member 37, through contact member 38 to spring 20, thence through spring support 13 to its terminal end 15. In its open position, since there is no longer an abutment between

contact members

37 and 38, the electrical path between

terminals

31 and 15 is broken and the switch will not conduct.

Adjustment of the operational parameters of the switch is accomplished by tightening or loosening the adjusting screws 32 thereby shortening or lengthening the free length of the screws and urging the central portion of midsection 16 of spring support closer to base 12 or allowing the midsection 16 to spring back further away from the base 12. As a result, the linear distance between

vertices

18 and 19 correspondingly diminishes or increases causing the original locking moment impressed upon the contained portion of spring 20 to likewise increase or decrease. The actuating force necessary to open or close the switch increases or decreases in like manner, since the actuating bending moment necessary has increased or decreased accordingly. Although it is not shown in the preferred embodiment disclosed, provision for over travel of the actuating body can be incorporated by reducing the width of spring 20 somewhere along cut out 22, making end 27 a relatively soft spring which will flex a relatively large distance without breaking ing, collapsing or failing in any way.

It should be noted here that increasing or decreasing the original bending moment impressed on the contained portion of spring 20, besides increasing or decreasing the necessary minimum value of the actuating force, also increases or decreases the speed at which the switch will act because a larger bending moment causes a more powerful springing action which in turn creates a faster acceleration of the spring body as it moves from one position to the other.

Embodiment 11 of the invention incorporates two supports 39 and 40 mounted on a U-shaped base 41.' The spring means now takes the shape of a symmetric elongated strip 42 having two

notches

43 and 44 at one end and two cutouts 45 and 46 along the lateral edges of-spring 42. Adjusting means here comprise two

screws

47 and 48 which extend through the legs of the base and thread into tapped holes inthe supports 39 and 40.

It is obvious that other modifications and variations may be resorted to without departing from the spirit and scope of the invention. For example, another contact pair on the opposite side of the spring may be incorporated to make a double-throw rather than a single-throw switch, as in the preferred embodiment. The spring member 20 could be designed to overhang both sides of the switch to provide two locations for applying the actuating force.

It should be understood of course, that the foregoing disclosure relates to only a preferred embodiment of the invention and that it is intended to cover all changes and modifications of the examples of the invention herein chosen for the purposes of the disclosure which do not constitute departures from the spirit and scope of the invention as set forth in the appended claims.

What is claimed is:

1. An electrical contact switch, comprising; a base; first support means mounted upon said base, said first support means having an aperture therein; spring means partially contained within two points of support on the circumference of said aperture, the portion of said spring means contained in said aperture being longer in length than said aperture in which it is contained, so that said contained portion of said spring means is retained arcuately within said aperture; first contact means located along the arcuately contained portion of said spring means; second support means afiixed to said base; and second contact means, mounted upon said second support, adapted to cooperate with said first contact means such that movement of said portion of said spring means contained within said aperture will cause said first and second contact means to engage or disengage, and a plurality of adjusting screws inserted through said first support means, the screws being threadably fitted to the base, the adjusting screws urging the first support means toward the base, the adjusting screws being adapted when rotated in one direction to elongate the aperture through the first support means, and when rotated in the opposite direction to shorten the aperture through the first support means.

2. An electrical contact switch as claimed in claim 1 in which said spring means is statically balanced about one of said points of support on said circumference of said aperture.

3. An electrical contact switch, comprising; a base; first support means mounted upon said base and having an aperture therein; spring means, partially contained within said aperture, the portion of said spring means contained in said aperture being longer in length than said aperture in which it is contained, so that said contained portion of said spring means is retained arcuately within said aperture; first contact means located along the arcuately contained portion of said spring means; second support means affixed to said base; second contact means mounted upon said second support means, adapted to cooperate with said first contact means such that movement of said portion of said spring means contained within said aperture of said first support means will cause said first and second contact means to engage or disengage; and adjusting means, adapted when adjusted in one direction to elongate said aperture of said first support means and when adjusted in the opposite direction to shorten said aperture of said first support means.

4. An electrical contact switch as in claim 3 in which the adjusting means consist of screws urging said first support means toward said base.

5. An electrical contact switch, comprising in combination; a non-conductive base; a support, mounted upon said base, said support having a portion spacedly disposed from said base, said portion having an aperture therein; an elongated resilient spring member having a notch at one end and a cutout along one edge, said spring member being supported by said support member by the abutment of said notch and said cutout against two points on the circumference of the aperture, the length of said portion of said spring between said notch and said cutout being greater than the distance between the two points on the circumference of the aperture wherein said portion of said spring member is contained; a contact member located upon said spring member, and electrically affixed thereto; a second support member, affixed to said second support member, and cooperatively disposed with said first contact member such that motion of said spring member will cause said first contact member and said second contact member to engage or disengage.

6. An electrical contact switch as in claim 5 in which said resilient spring member is statically balanced about at least one of said abutting points.

7. An electrical contact switch, comprising in combination; a mounting base; a resilient spring support member mounted thereon, a portion of said spring member being spacedly disposed from said mounting base, said portion having an aperture therein; a resilient spring member, having a notch at one end and a cutout along one edge, said spring member being supported by said support member by having a point in said groove and a point in said cutout abut two points on the circumference of said aperture, the length of the portion of said spring member between said point in said groove and said point in said cutout being greater than the distance between said two points on the circumference of said aperture which said points in said groove and said cutout abut; a contact member afiixed to said spring member between said groove and said cutout; a second support member afiixed to said base; a second contact member afiixed to said second support member, and cooperatively disposed with said first contact member, such that movement of said portion of said spring member between said groove and said cutout will cause said first contact member and said second contact member to engage or disengage; and an adjusting member adapted when adjusted in one direction to diminish the distance between the said two points on said circumference of said aperture against which said point on said groove and said point in said cutout of said spring member abut, and when adjusted in the opposite direction to elongate said distance between said two points upon said circumference of said aperture against which said point in said .groove and said point in said cutout of said spring member abut.

8. An electrical contact switch comprising; a base having two legs; resilient first support members opposedly mounted upon said legs, said resilient support members each having apertures therein; a resilient spring member having two notches at one end and cutouts on each side, each said cutout being at equal distance from its respec tive notch, said spring members being partially contained within said apertures, a point on each of said notches and each of said cutouts abutting against two points on the circumference of their respective apertures, said distance between said abutting points of said spring member being longer in length than the distance between said points of abutment on said circumference of said aperture; first contact means aflixed to said spring member; a second support mounted on said base; second contact means mounted on said second support and cooperatively disposed with said first contact means so that they will engage or disengage upon movement of said contained portion of said spring member; and screws urging said first support members toward their said respective legs of said base.

References Cited in the file of this patent UNITED STATES PATENTS 1,694,569 Walsh Dec. 11, 1928 1,695,103 Hook Dec. 11, 1928 2,773,145 Immel Dec. 4, 1956 FOREIGN PATENTS 956,154 France July 18, 1959