US2291019A - Snap action switch - Google Patents

Description

W. A. BIERMNN ETAL SNAI.l ACTION SWITCH Filed Hay 19, 1941 July 22, 1942.

Patented' July 2s, 1942 i'rEo STATES 'rN OFFICE mtime -s'NAP Ac'rroN swi'rc Application May 19, i941, Serial No. 394,066 y (Cl. wila-6T) a ola.

This invention relates to electric circuit interrupters, and more particularly to that type of interrupter commonly known in the art as a snap action switch and may be employed where a quick make and/or quick break of the electrical contacts is required.

Another object of the novel invention `is to provide a snap action switch which maintains 'a constant maximum contact pressure up to the breaking point.

A still further object of the device of this invention lies in the provisionof a circuit interrupter of the snap action type wherein the pivot point of the actuating member is moved when it is desired to break the circuit in order lto decrease the time interval between maximum contact pressure and rio-contact contact pressure to a minimum.

A further important improvement lies inthe use of a device of this invention using a 'floating pivot lwhere it is imperative that the actuating means overtravel -or go beyond the actualadistance required to snap the `switch from one posiwhich the time interval between maximum contact pressure and no-contact pressurewould be zero.. Of course, it is theoretically impossible to have suchk a condition of zero time but this time interval can be reduced to a minimum and it is a purpose of our invention to do this'. 'It isvwell lknown in the art that maximum contact pres- ,sure is desired at all times up to the break point to prevent frying or burning of the contacts.

Our invention further resides in the Vcombination, construction and arrangement of parts shown in the accompanying drawing; and while we have illustrated therein preferred embodi- Figure 3 is a vertical sectional view partly in elevation of a modified form ofthis invention.

Referring in detail to the drawing and more particularly to Figure 1, the illustrated embodimerit of our novel invention comprises a base YIII which may be made of kany insulating material or plastic composition such as Bakelite or the like. Removably secured to the base I0 is a` cover II which may be made of the same material as the base. A switch supporting bracket I2 is securely mounted to the base Ill by tubular rivets I3! which are drilled and tapped for the reception I of conductor holding screws I4. Contact supports I5 and it which are made of electrical conducting material are also rigidly ysecured to the base It by tubular rivets I3 which are tapped for the reception of screws I. Contacts Il which may be of 'any suitable material such as silver are riveted or otherwise securely fastened to the contact supports l5 and I6 in some conventional manner.

Two upstanding posts I8 disposed on either side of the supporting bracket I2 and integral therewith or fastened thereto carry the switch blade designated generally by the numeral I9. vThe switcliblade I9 which is in the form of a `leaf spring or resilient strip and which may be made of any suitable electrical conducting material is securely xed to the upstanding posts I8 by rivets 2li which are adapted to interengage the posts I8 and support I2. A washer disposed'between the head of the rivet 20 and the resilient stripl 1 i@ provides a more positive means for holding said resilient strip securely to the upstanding Y post i8. The switch blade or resilient strip I9 is comprised of a front cantilever member 22 which carries the contacts 23, and a second or rear cantilever member 24 which carries the center actuating member 25. The center member 25 is ments it is to be understood that the same are v susceptible of modification and change without departing from the spirit of our invention.

In the drawing:

; Figure 1` is a top plan view o f the preferred iform. ofthe device of this invention with the 'cover rexnoved;

FlgureiZv is a vertical crossLsectionfpartly in an integral part of the switch blade I9 in they present' embodiment but this is a matter of mechancal expedient or productional advantage. f The center actuating member 25 is reinforced with a substantially non-resilient element 26 to form a rigid center member 30. The non-resilient element 26 is secured to the member 25 in any suitable manner such as rivets 4.

' The non-resilient element 26 and the resilient member 2,5 pivot about an imaginary axis 8 of the rear cantilever member 24 and are free to move upwardly or downwardly, thereby providing a.

floating pivot for said member 30. Interpolated enlarged' button 42 having a conical element 43'.

integral its lower end is securely attached to the stem 40 and limits the upward movement of said stem. The conical element 43 may be made to contact the rigid member 30 and successfully actuate it,any place between a center line drawn,

transversely through the posts -I8 and the pivot point 6 of the rigid member on the rear cantilever arm. A compression spring 44 is disposed beneath the rigid actuating member 30 and'is in vertical axial alignment with the actuating stem 4I) and conical element 43. `The upper convolutions of the spring 44 abut the rigid member 30 and the lower convolutions abut the supportting bracket I2. Both the upper and lower convolutions of the spring encircle integral projections of the members 30 and I2 respectively to constrain the spring in position. Depressing the stem 40 moves the actuating arm 25 downwardly and compresses the spring 44 disposed beneath said arm. The force built up in the spring 44 urges the actuatingarm 25 upwardly to the position shown in Figure 2 when the external force is removed from the stem 40.

The modied form of this invention comprises a base I8, and a cover 5| having a slot 52 in one of its ends thru which a rigid actuating arm 54 extends. A supporting bracket I2, and contact supports I5 and I8 are mounted on the base I8 in the manner describedin the preferred embodiment of our invention. The supports I5 and I5 carry the contacts I1 which co-act with the contacts23 carried by the cantilever arm 22. Upstanding posts I8 which may be an integral part of the supporting arm I2, or riveted thereto, carry the switch blade I 8, said switch blade being fixed to the posts in the same manner as hereinbefore set forth. The switch blade or resilient strip I9 has a front cantilever member 22 and a rear cantilever member 24 to which is pivotally secured and integral therewith a4 center actuating resilient strip I9, to which the rigid member 54 is`l immovably connected rotates with the actuating arm 54 when a force is applied 'at any point between the pivot axis of said arm and an innite number of points to the left of said pivot axis as viewed in Figure 3. The pivot axis of this arm which pivots about the rear cantilever may be found mathematically or empirically. The stops 38 -and 39 are an integral part of the upturned element of the supporting arm I2 and limit the throw of the member 25 vertically.` A compression spring 32 is disposed between the end of member 25 and the cantilever member 22. The ends of the spring abut cupped shaped elements 33 which are recessed for the reception of bearings such as 38 and 31.

Many of the parts shown in the modified form are interchangeable with similar parts of the preferred embodiment as indicated by the parts having the same numeral in both forms of the invention. The major difference in the two devices lies in the point of application of the actuating force to the actuating arms.

. A force applied to a predetermined point on the actuating arm of either embodiment of our invention will (referring to Figures 2 and 3) first move the pivot4 point about which th'e actuating arm theoretically revolves and then the continued application of this force will bring the actuating arm and its supporting member into balance with the force components of the front cantilever member and the coiled spring. After equilibrium is reached the continued application of force will cause the switch to snap across center.

Moving the pivot point of the actuating lever enables us to maintain a maximum contact pressure up to the breaking point of the circuit. This is because the toggle action of the actuating arm is delayed until the final snap action over center is required. The force applied to the actuating arm may be in the form of a manually operated button as shown, temperature responsive element and etc.'

Having described the invention, we claim:

l. In a device of the character described, a supporting bracket, a resilient strip mounted on the supporting bracket beyond its mid-point, and electrical contacts carried by one end of said strip and a rigid actuating member carried by the other end of said strip, a center member fixed to said rigid actuating member, a spring interposed between said center member and the resilient strip, actuating means for said actuating spring, center member integrally related to saidV leaf spring and secured to the non-resilient member and adapted to rotate therewith, means providing -a floating pivot for said non-resilient member, current carrying contacts carried by the other end of said leaf spring, a compression spring interposed between' said center member 'and the other end of saidleaf spring, contact carrying supports having electrical contacts thereon, said electrical contacts co-operating with the current carrying `contacts on said leaf spring to complete an electrical circuit, stops associated with said supporting bracket.

3. A snap action switch comprising a supporting bracket having a leaf spring secured thereto, said leaf spring having ends free to move vertically, a non-resilient actuating member hingedly attached to one end of the leaf spring and free to rotate about one end of said leaf spring, a center member secured to the non-resilient member, one of said free ends of said leaf spring providing a floating pivot for saidv non-resilient member, current carrying contacts carried bythe other end of said leaf spring, a compression spring interposed between a point adjacent one end of said non-resilient member and said leaf spring, contact carrying supports having electrical contacts thereon, said electrical contacts cooperating with the current carrying contacts on said leaf spring to complete an electrical circuit, stops associated with said supporting bracket.

4, A switch blade provided with a center member hingedly connected thereto, a supporting bracket for said switch blade, a compression spring interposed between said center member and one end of said switch blade and normally biasing the center member away from the switch bladea non-resilient member carried by the other end of said switch blade and secured to said center member, said non-rilient member being free to rotate about a movable pivot axis and thereby provide a delayed toggle action for disposed and movable in the same direction when y cantilevers and free to move vertically to change the pivot axis of the actuating member, a spring interposed between 4 the actuating member and the other cantilever member whereby said cantilever member is biased to build up a vertical component of force' in said cantilever member, contact carrying supports cooperating with said last actuated with respect to said supporting bracket,

an actuating member carried by one of saidY different balanced coil connected to the free en`d of one of saidI canti-i levers and free to move vertically with said cantilever to change the pivot point of said non-resilient member, a center memr xed to said non-resilient member, external means for operating said actuating member, means disposed adjacent said actuating member tor returning said actuating member to normal position, current carrying contacts carried by the other cantilever, a spring interposed 'between the center member and said last named'cantilever member, contact .carrying supports having electrical contacts thereon which .cooperate with the contacts carried by one oi' said cantilevers, stops for said actuating member.

, 8. In a device oi' the class described, the combination of-a switch supporting bracket, a switch blade mounted on said supporting bracket and comprising two cantilever members acting -on opposite sides of the supporting bracket, an actuating member hingedly connectedto one of said cantilever members, a coiled spring interposed between said actuating member and the other of said cantilever members, means associated with said switch bladewto compensate for 'ings, electrical contacts carried by on of said cantilevers, contact carrying suppoijs having contacts amxed thereto and cooperating'with the contacts on said cantilever,stops for said actuating member;

named cantilever member. and stops iorlimiting the vertical movement of the actuating member, means for rotating the actuating member.

6. In a device of the class described, the com bination of a switch supporting bracket, a exible cantilever member on either side of said bracket the free ends of 'which are adapted to move vertically, a non-resilient actuating erinconnected 9. In a device of the class described, the combination. of a base, a cover having an opening therein and adapted to nt the base, a switch supporting bracket mounted on the base, a switch blade secured to the supporting bracket and forming a iront and a rearcantilever member, said front and rear cantilever being hingedly connected tol said switch supporting bracket, a

rigid actuating member. hingedly connected to the rear cantilever member and having a movable'pivot axis, a spring between the rigid actutothe free end of one of said cantilevers and free to move vertically with said cantilever to change the pivot point of said non-resilientA member, center member xed to said resilient member, current carrying contacts carried by theother cantilever, a spring interposed between said center member ,and the last named cantilever 7. In a device of the class described, the comating member andthe iront cantilever member,

contacts carried by the iront cantilever member,

an external actuating pin extending through said cover and terminating within said cover, means for returning said rigid actuating memberIto its normal position after the external actuating pin v is released, and stopsk for limiting the vertical .65 bination o! a switchsupporting bracket. a x'elsil-- ient cantilever member on either side ofrsaid travel oi said rigid actuating member,

1 WILLIAM -crznarc n. zARwnm.-

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