US 3427418 A
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A. R. NORDEN 3,427,418 SWITCH UTILIZING A COIL SPRING COACTING WITH Feb. II, 1969 SILENT A.C
ABUTMENT TO PROVIDE A CUSHIONED EFFECT Sheet Filed June 22, 1967 I INVENTOR ALEXANDER R. NORDEN BY Q M V aToRNsvs z Feb. 11, 1969 N E 3,427,418
SILENT A.C. swmcn UTILIZING A COIL SPRING COACTING WITH ABUTMENT TO PROVIDE A CUSHIONED EFFECT Sheet 2 of 2 Filed June 22, 1967 (0 0 an a g 1 m l w w INVENTOR ALEXANDER R. NORDEN ATTORNEYQ BY%*M United States Patent York Filed June 22, 1967, Ser. No. 648,006 US. Cl. 200-166 C Int. Cl. H0111 9/02 laims ABSTRACT OF THE DISCLOSURE This disclosure describes a switch of the silent A.C. type for use as a wiring device in building wiring circuits with a coil spring over-center toggle action wherein silencing is provided by virtue of a structure which contacts the sides of and distorts the coil spring in the extreme positions of the operating lever movement so that the coil spring acts as a cushion preventing abrupt contact of moving parts at the extremes of the movement and reduces the noise. The coil spring is subjected to two forms of distortion, the usual axial distortion responsible for the off-center bias of the operating lever and a nonaxial distortion for cushioning at the extremes of movement.
The switch of the present invention represents an improvement over existing switches of the silent A.C. type.
A.C. type switches are characterized by having a relaswitches relatively silent in their operation and various expedients have been employed such as the use of rubber bumpers for cushioning the operating lever or handle at the extremes of its movement. Prior successful expedients for providing silent action have typically required additional parts in the switch which add to the materials cost and also complicate the assembly operation and increase labor costs.
According to the present, invention a silent switch movement is provided wherein cushioning and silencing action is obtained by distortion of the coil spring which is already present for the purpose of biasing the operating lever off center. The structure for contacting and causing distortion of the coil spring may be molded into the switch housing so that virtually no extra material and no additional parts are required. The structure of the invention is equally effective as prior silencing expedients, and in addition to being simpler and cheaper, it is more durable than such structures as rubber bumpers which may in time become hardened and less effective.
In addition to providing the advantages described above, it is an object of the present invention to provide a silent A.C. switch wherein the silencing means requires an insignificant increase in materials and requires no additional parts to be assembled.
It is another object of the invention to provide such a switch wherein the cushioning and silencing is provded by distortion of the over-center coil spring and in which no bumpers of rubber or like material are required.
3,427,418 Patented Feb. 11, 1969 Other objects and advantages will be apparent from a consideration of the following description in conjunction with the appended drawings in which:
FIG. 1 is a vertical sectional view of a switch according to the invention;
FIG. 2 is a sectional view of the switch of FIG. 1 taken along the line 2--2 in FIG. 1; and
FIG. 3 is a sectional view of the switch of FIG. 1 taken along the line 33 in FIG. 1.
Referring to the drawings, a silent A.C. switch is shown having a housing 12 and a cover 14 shaped and adapted to provide an enclosure for the switch mechanism with an opening 15 for the operating lever portion 24 of handle 22. A conventional metal mounting strap 16 is provided and the housing 12, cover 14, and strap 16 are secured together in any suitable manner such as by rivets 18 passing through holes 20 in the housing 12 and through appropriate openings in cover 14 and strap 16.
A handle 22 comprises an operating lever portion 24 and a pair of cylindrical extensions 26 for pivotally mounting handle 22. The cylindrical extensions 26 rest in a depression between pillars 28 formed integrally with housing 12 and handle 22 is further retained with freedom of pivotal movement between humps 30 formed in the cover 14. A projection 32 with a camming surface 33 is formed on the handle 22.
The handle 22 is generally restrained at the extremes of its movement by the over-center spring 36 as will later be described in detail. However, posts 38 are provided in housing 12 to prevent in cooperation with the oblique faces 37 over travel of handle 22.
The toggle handle 22 is provided at its lower end with a. projection 34 which is engaged by a compressed coil spring 36. The lower end of the coil spring 36 rests on a post 35 formed in the housing 12 and which is of a shape generally similar to that of projection 34.
Both projection 34 and post 35 have their greater dimension parallel to the axis about which handle 22 pivots; this may be seen, for example, in FIG. 2. This provides substantially two-point contact between spring 36 and projection 34 and post 35 respectively so that the distortion of spring 36 due to the relative movement of projection 34 and post 35 would be only axial compression.
Since the spring 36 is compressed to the greatest extent for the center position of handle 22, an over-center action is provided whereby the handle 22 is urged to the two extremes of its movement by the action of spring 36 in conjunction with projection 34 and post 35.
From the description of those portions of the device set forth thus far, it would be expected that the handle 22 would be subjected to an over-center bias which would cause it to be accelerated rapidly from its center position to an extreme position where it would come to a sudden stop either by virtue of a face 37 striking a pillar 38 or due to the lever 24 striking the side of the hole 15 in cover 14. Such action would result in a substantial noise or snap which previous switch designs endeavored to avoid by rubber bumpers or other expedients.
A cushioning effect is provided in the present device by abutments 40 and 42 of arcu-ate shape which come in contact with and distort the spring 36 as the handle 22 approaches its extremes of motion.
The distortions caused in the spring 36 by the arcuate abutments 40 and 42 are such as to decelerate the motion towards its extreme position of the handle 22 in gradually increasing degree. The action of spring 36 against abutments 40 and 42 is highly effective to cushion the handle 22 at its extremes of movement so that it is decelerated to a stop with substantially no noise and little rebound.
It should be noted that the deceleration of handle 22 as a function of its position may be determined accurately by the shape and position of abutments 40 and 42. These abutments may take the form of arcs of circles or other curves providing the desired functional relation between deceleration and position. It is desirable that decelerating force from spring distortion be applied gradually after closure of contacts 70 and 76 thereby permitting the application of the total force of leaf spring 66. It will be noted that such is the case in the arrangement of FIG. 1 wherein the cam follower portion 68 of leaf spring 66 is lifted well clear of camming surface 33 by the time handle 22 has been decelerated to rest in the on position.
The electrical circuit of the switch is best seen by reference to FIGURE 2. A first contact member 44 is provided in housing 12 and may be formed with a wire gripping portion 46 to rovide a push-wire type terminal permitting electrical connection to terminal member 44 by insertion of a bared conductor wire through Opening 48 in housing 12. A conventional terminal screw 50 is also provided to permit electrical connection of a conductor wire to terminal member 44 in the conventional manner by being wrapped around and tightened under screw 50. The terminals which are illustrated form no part of the present invention and other forms of terminals may be substituted for use with the operating portion of the switch movement according to the present invention.
Terminal 44 has a rigid extension 64 to which there is connected a leaf spring 66 by a rivet or other suitable means. Terminal 44 may be secured in the housing 12 by being captured in slots 52 provided in housing 44.
Disposed in housing 12 substantially symmetrically to terminal member 44 is a second terminal member 54 having a wire gripping portion 56 adapted to capture a conductor wire inserted through hole 58 in housing 12 and also having a conventional terminal screw 60 all of which are secured in housing 12 by engagement of terminal member 54 with slot 62 in housing 12. Terminal member 54 has a rigid extension 74 on which is mounted a contact 76 preferably made of silver or other appropriate contact metal or alloy. Contact 76 cooperates with a similar contact secured to the end of leaf spring 66.
Leaf spring 66 is bent to form a cam follower portion 68 which cooperates with the camming surface 33 of handle 22. When lever 24 is operated to the left in FIG. 1, camming surface 33 depresses cam follower portion 68 of leaf spring 66 separating contacts 70 and 76 and opening the electrical circuit controlled by the switch. The handle 22, when in the position shown in FIG. 1, creates no downward displacement of the leaf spring 66 so that the contact 70 and 76 are pressed together by the resilience of leaf spring 66 thereby completing the electrical circuit between the two terminals 44 and 54 of the wiring device.
It may be noted that the reaction of the leaf spring on the camming surface 33 produces some bias urging handle 22 to the right. While this bias is small compared to the bias provided by coil spring 36, it may be desired to counteract the effect of leaf spring 66 by an asymmetric placement or shaping of arcuate abutment 40 with respect to arcuate abutment 42. Thus, abutment 40 may be shaped or positioned to give greater central thrust on spring 36 than does abutment 42, so there will be a tendency to compensate for the bias due to leaf spring 66. In some cases leaf spring 66 may be arranged to provide most or all of the cushioning effect for travel of handle 22 in one direction and in the latter case abutment 42 may be omitted.
It should be noted that the shape and position of abutments 40 and 42 is subject to wide variation commensurate with the function of creating non-axial distortion of spring 36 which will impart a force to handle 22 at the end of its travel substantially counteracting the acceleration due to axial compression of spring 36.
It will be obvious to those skilled in the art that a single pole single throw switch is illustrated for simplicity only and by way of example and that the invention may readily be applied to double throw and/or double pole switches.
Further variations and modifications of the invention will be apparent to those skilled in the art and accordingly the scope of the invention is not to be limited to the particular embodiment shown by way of example but is to be defined by reference to the appended claims.
What is claimed is:
1. A switch comprising a switch body, an operating member movably mounted in said switch body, two contacts in said switch body at least one of which is movable between closed and open positions by said operating member, a coil compression spring mounted between said operating member and said switch body for maximum compression at a point between the extremes of movement of said operating member representing fully open and fully closed positions of sai contacts, and a spring distorting member positioned to exert a distorting force on said spring to produce non-axial distortion thereof for positions of said operating member and spring near an extreme of movement of said operating member, said non-axial distortion of said spring producing a force on said operating member opposing that produced by the axial compression of said spring.
2. A switch as claimed in claim 1 wherein the movable one of said two contacts is mounted on a leaf spring biased to urge the movable contact against the other of said two contacts, the last said contact being fixed.
3. A switch as claimed in claim 2 wherein said leaf spring has a cam follower portion and said operating member has a camming surface portion cooperating therewith to move said movable contact in response to movement of said operating member.
4. A switch as claimed in claim 1 wherein said spring distorting member is an abutment with an arcuate surface over which said spring is bent as said operating member approaches an extreme of movement.
5. A switch as claimed in claim 1 further including a second similar spring distorting member for distorting said spring at the other extreme of movement of said operating member.
6. A switch as claimed in claim 5 wherein said spring distorting member and said second spring distorting member are asymmetrical with respect to said spring thereby providing unequal spring distorting forces.
7. A wiring device of the silent A.C. switch type comprising an enclosure including a housing and a housing cover, a handle member including an operating lever extending outwardly through an opening in said cover, means for pivotally mounting said handle member about an axis extending between opposite sides of said housing, a movable electrical contact controlled by movement of said handle member and a second electrical contact cooperating therewith, means for biasing said handle member away from a central position and toward two opposite off-center positions including a coil spring in a compressed position between said housing and a projection on said handle inwardly extending from the handle axis, at least One spring distorting element comprising a rigid abutment formed as a unitary part of said housing positioned to produce non-axial distortion of said spring as said handle approaches an extreme of its movement thereby gradually decelerating the handle in a relatively noiseless manner, and two terminals, each electrically connected to a respective one of said contacts for connecting said switch in an electrical wiring circuit.
8. A wiring device as cla irned in claim 7 further in- Referen es Cited a leaf spring on which one of sa1d contacts 1s UNITED STATES PATENTS 9. A wiring device as claimed in claim 8 wherein said 1,645,387 10/1927 Kinneyleaf spring has a cam follower portion and said handle 5 FOREIGN PATENTS meember has a cammmg surface portion cooperating 529,866 9/1956 Canada.
therewith to move the contact afiixed to said leaf spring in response to movements of said handle member. ROBERT K. SCHAEFER Primary Examiner 10. A switch as claimed in claim 1 wherein said spring distorting member comprises a rigid abutment formed 10 BURKS, ASSiSfant Examinerintegrally with said switch body over which said spring is us CL XR. bent as said operating member approaches an extreme of movement.