US2651690A - Electric snap switch - Google Patents

Description

sept. s, 1953 E. c. RANEY ELECTRIC lSNAP SWITCH Filed June 17, 195o ma www# INVEN TOR. 557-51. C'. Pa/sy Patented Sept. 8, 1953 2,651,690 ELECTRIC SNAPv SWITCH Estel C. Raney, Delaware, Ohio,

assgnor to Ranco Incorporated, Columbus, Ohio, a corporation of Ohio Application .Tune 17, 195o, serial No. 168,747

The present invention relates to snap acting mechanisms and more particularly to a double throw electric snap acting switch mechanism.

An object of the present invention is to provide a new and improved overcenter type snap acting electric switch mechanism having acontact carrying member which moves with a snap movement in opposite directions between spaced xed contacts and in which a substantial contact pressure is maintained against the respective fixed contacts until the instant of movement of the movable Contact to the other fixed contact. 1

Another object of the invention is to provide a new and improved snap acting electric switch having a contact carrying strip urged to one or the other of two spaced fixed contacts by a spring, the force of which is applied to the contact strip through a toggle arm or lever which is snap operated by the spring and which arm is adapted to carry the spring with a snap movement through the dead center position of the spring and the contact strip to cause the spring to snap move the strip from one of the contacts to the other in opposite directions without gradual reduction in contactpressures.

Another object of the invention is to provide a novel, relatively compact snap electric switch structure having a snap acting contact carrying member which is snap actuated in opposite directions by relatively short movements of an actuating member and in which a substantial contact pressure is maintained until the instant of movement of the contact carrying member.

Other objects and advantages of invention will be apparent from the following description of a preferred form of the invention, reference being made to the accompanying drawings where- 1n:

Fig. 1.is a plan view of a double throw electric switch embodying the invention; Y

Fig. 2 is a sectional view taken substantially on line 2 2 of Fig. 1; and

'Figs 3, 4, 5, 6 and "I are diagrammatic views illustrating the relationships of various parts of the snap switch during operating movements of thc switch mechanism.

'Ivhe invention is particularly useful as ernbodied in double throw switches in which it is desirable to have a movable contact powered by a relatively slow moving actuator through a snap mechanism to snap the contact between two spaced xed contacts to maintain a positive contact pressure until the instant of snap movement. The present invention contemplates a 2 Claims. (Cl. 200-67) contactstrip pivoted at a relatively fixed point at one end and having a Contact member at the opposite end movable between two spaced fixed contacts by shifting of the far end of the contact strip. A toggle lever or arm is pivoted on the strip adjacent to the Contact carrying end and extends generally toward the pivoted end of the strip. A spring is connected at one end to the unpivoted end of the toggle arm and continually urges the arm in the direction of its pivot, and the unpivoted end of the toggle arm has limited movement in the direction of movement of the strip so that the part of the spring connected thereto is shifted by the toggle arm to change its component of force on the contact strip to move the strip from one fixed contact to the other. The spring is connected at its other end to an actuating member which has the part to which the spring is connected movable in the direction of movement of the stripv so that the actuating member may move relatively slowly to shift the center of force of the spring on the toggle arm from one side to the other of the dead center position of the spring and toggle arm, which dead center position is passed prior to the establishment of the dead center condition of the spring force and the Contact strip so that the latter condition occurs only after the toggle arm has passed its dead center position and is moving with a snap action. By this construction the contact strip is maintained biased to either of the fixed contacts and is moved from one contact to the other by shifting of the spring by a snap movement imparted thereto by the toggle arm. The contact pressure is constant and substantial up to the instant the contact strip is moved in the opposite direction although the actuator may have an extremely slow or unsteady movement.

Referring now to the drawings, for the purpose of illustrating the invention, I have shown a double throw electric switch which may be actuated by any suitable means, such as a manually operated button, a pressure responsive ele- Y ment or a thermostat, or other suitable devices. As shown, the switch mechanism comprises a base l0, which is formed of a suitable insulating material having a conductor bar Il attached thereto and which bar carries a fixed contact member I2. The bar Il preferably extends through a slot in the base member to :facilitate connection of the contact I2 in one electric circuit controlled by the switch but which is not shown.

A second contact l5 is supported in spaced re- 3 lation and immediately opposite contact I2 on an inverted U-shaped bracket I6 suitably attached to the base I and having one leg II thereof extending through the base similarly to the bar II for connection in another circuit, not shown.

A contact carrying strip 20 is attached at one end to a metal bracket `2i which -is secured to the base IS and the opposite or outer end 'of the Strip extends between the fixed contacts I2 and I5, and a double contact 22 is attached to the outer end, which Contact is adapted to alternately engage contacts I2 and I5 as the strip `oscillates vertically as viewed in the drawings. The bracket 21 has a leg 23 extending through #an opening through the base for connecting one end of the contact strip in a circuit common to the circuits of contacts l2 and f5, but not shown. The strip 28 is preferably formed of a .-flexible, U-shaped resilient member adapted to flex about the end attached .to bracket 2.I so that .the .contact carrying end may shift between Acontacts I2, I5. Preferably, `opposite sides of the strip 20, except adjacent to its pivoted fend, havedownwardlyextending flanges, one of whichis shown at 24, to stifen .the .majorportion of the Astrip. As fan alternate construction, the .strip 20 could be relatively rigid and pivoted tothe bracket 2-I by a knife -edge bearing structure to cause the free -end to be swung between the contacts I2, .E rather than iiexing the member to achieve this end, as shown. It is lto :be runderstood that .although the strip 2G is .shown as -exible at lits secured end, it nevertheless pivots .at that end.

The contact carrying end of the strip 2b is adapted lto besnap actuated 'between the contacts I2 and I5 by Ya toggle -arm :25 `and a spring ,26. The toggle arm 25 comprises a `U-shaped member having the outer ends -of .the two legs thereof notched'as vindicated at -21 fand .,pivotedon beveled end lugs `28'iormed opposite edges of the opening through the strip v2l) and adjacent .to .the contact 2-2 and'engaging inthe-apexes of the .notches to provide knife -edge bearings for-the toggle arm. The toggle arm extends generally toward the anchored end `of the strip 2B and is ,provided with upper and .lower flanges 2.9, 30 which .are adapted to 'abut opposite sides of `va tongue .3.-I forming a part of bracket -2-I to limit .oscillation of the toggle about its pivot.

The toggle arm -25 is adapted .to be snap-actuated between its limit of lmovement-by the spring 26, -one end of which is attached to an actuating member 32 at a point beyond the ypivot for the legs of the toggle arm and the other end `of which is attached to the yoke portion 5oi .the ztoggle arm and intermediate the flanges 29 3i). Theactuating member 32 comprises a ysheet metal l:member having two parallel web portions 33, 4:iii projecting from opposite sides thereof and notched as at '35 to receive lugs 33 formed integral with the bracket 2| and forming pivots for the actuating member. The opposite end of the member 32 has 'a tongue portion 39 projecting laterally therefrom to which the spring 2-6 is attached `by extending -a hook portion of the spring through an opening in the tongue. The tongue -39 is adapted to be swung in the direction of movement Vof the lcontact strip r20 and to move from one side to the other of a plane extending through the .strip 2U and normal to the direction of movement of the latter.

When the line of force of the tensionspring A26 is inclined relative to a line through the ,point of connection of the spring with the toggle arm Afloracket 2l, the spring force urges the contact carrying strip 20 to contacts I2 or I5, as the case 'may be.

Asthevactuating member 32 is moved from the position-shown in Fig. 3, to that shown in Fig. 5, for example, i.the line of force of spring 26 will come into coincidence with the line (1 -c, as seen in Fig. 4, at'whichtime the force of the spring tending to urge the toggle member to one or the other of its limiting positions is in equilibrium or deadcenter., andalthough the .pressureof thestop fiange 3U on the .tongueI isnil, Ithe component o force .of .spring 2.5 tending -to close'contact .22 on .contact .1.2 remains .unchanged and -oi .a substantial .nature .since the line of .force remains above .the :pivot .point on -point of fiexure of the strip 2D as indicated bythe line a-a. Continued downward .movement .of theactuating vmember 32 causes .spring -26 to pass its dead lcenter `position relative to the toggle arm, at which .instant `the toggle arm .is snapped .downwardly to bring yilange 29 .into .engagement with .tongue -3 I. This movement instantly passes the spring through its dead center .position .relative .to the -contact .strip .20 since .the -toggle .arm is beyond .its dead center position .and .traveling .under torce of vthe spring. This condition is .shown .in .-F'ig. 5. As thetcggle arm snaps to the .position vshown -in Fig. .6, .it changes lthe component of Aforce of .the spring A2li on the contact .strip .28, illustrated b-y the broken line a-c of Fig. A6, .and the .contactcarrying end of thestrip-Z .is snapped .upwardly to move `contact .24 againstcontact I5.

For lthe sake or clarity, in the dra-wings., the actuatorSZ -is shown to Ymove througha considerable angle to operate the contact str-ip 2S, but actually it need ymove through .an-angle only sufficiently to 'move the outer end of the spring 2B slightly outside the limits-defined r`by Athe strip 2U in its alternate positions.

The operation of the switch in the opposite direction is similar and the str-ip 2B :is snapped downwardly :instantaneously and without a :gradual reduction Iin contact pressure.

VBy my novel combination a Aheavy contact pressure is maintained on either of the contacts I2, Il5 until the instant 'of shifting of 'the contacts and :regardless of the gradual movement of the actuating member so that a minimum Vor arclng results which Veffects long life of the contacts and positive control of Athe rcircuit in which the switch is connected.

In addition to `the operating advantages of the switch mechanism, the .arrangements of the various elements thereof .permit inexpensive manufacture of the mechanism. For example, the tension of .spring 26 maintains the notches 21 of the toggle .arm in pivotal engagement with the lugs 2B of the vstrip 20 and the notches 35 of the actuating -member 32 in pivotal engagement with lugs 3l' of the bracket 2|. In the embodiment .of the .invention shown, the spring 26 tends to urge the actuating .member yclockwise about its pivot, .but .by relocating the position of lugs 3l,

38, the actuating member could be biased in the switch operating position shown in Fig. 6.

By my invention, I have provided a compact, positive acting double throw switch which can be operated by a relatively small actuating force as compared to the amount of contact pressure provided thereby and which is particularly useful for operation by thermostatic or pressure responsive elements.

Although I have described but one form of the invention, it is to be understood that other forms could be adapted all falling within the scope of the claims which follow.

Having thus described my invention, I claim:

1. In a snap switch, supporting structure, a contact carrying strip supported at one end and and having the legs thereof pivoted at one end on said strip adjacent to said opposite end of said strip, the yoke end of said toggle arm being swingable through the opening in said strip, an actuating member having a part movable through the opening in said strip, a spring interconnecting part of said actuating member and the yoke of said toggle arm and arranged to urge the toggle arm in the said spring with said cluding two spaced stops associated with said toggle arm for limiting swinging of said toggle arm to cause said point of connection of the spring therewith to swing between positions on opposite sides of a plane through the said strip and normal to the strip.

2. In a snap switch, a supporting structure, a contact carrying strip supported at one end by said supporting structure and adapted to have its opposite end move between two spaced stops, said strip having a central, longitudinally extending opening, a relatively rigid U-shaped toggle arm disposed in said opening and having the legs thereof pivoted at one end on said strip adjacent to said opposite end of said strip, the yoke end of said toggle arm being swingable through the opening in said strip, an actuating member having a part movable through the opening in said direction of movement of said strip, a spring interconnecting said part of said actuating member and the ESTEL C. RANEY.

References Cited in the le 0f this patent UNITED STATES PATENTS Number Name Date Re. 17,646 Johnsson Apr. 22, 1930 2,228,523 Johnson Jan. 14, 1941 2,508,040 Ransome May 16, 1950

Images