US2226772A - Electric switch - Google Patents

Description

Dec. 31, 1 940. A. A. JoHNsoN ELECTRIQ SWITCH Filed Sept. 13, 19:58

Patented Dec. 31, 1940 *UNITED STATES ELECTRIC SWITCH .Arthur A. Johnson, New Bedford, Mass., 'assignor to John I. Paulding, Inc., New Bedford, Mass. a corporation of Massachusetts Application September 13, 1938,'Serial No. 229,652

14 Claims. (C1. 173-355) This invention relates lto electric switches and more particularly to a switch 'of the push button type, and is exemplied herein in a switch adapted for use in an electric lamp socket.

Heretofore, in this type of switch, consider-able diiculty has been experienced because of ,undue arcing which shortens the life of the switch and prevents its use for high voltage currents. This excessive arcing is due to the fact that in the operation oi the switch there is a short interval of time during which the engagement of the switch member with the iiXed contact is a loose engagement, and this may occur when the switch is operated either to close or to open the circuit controlled by it. Such excessive arcing causes a corrosion of the switch member which, in time, renders'the switch inoperative. Furthermore, a switch which is open to this objection is not adapted for use in high Voltage circuits.

The particular object of my invention is the provision of a switch of the character described, which is of simple construction having a minimum number of parts,- which is eiilcient and durable, and which is adapted for use in high voltage circuits.

A more specic object of the invention is the provision of a switch mechanism in which the switch member is operated so rapidly to close and to open the circuit controlled by it that the time during which arcing may occur is reduced to a minimum, thereby eliminating any undue arcing Other objects of the invention will bein part obvious Vand in part set forth hereinafter'. l

My invention contemplates a switch mechanism in which a` switch member held by a reciprocable actuating member in. engagement with a resilient portion of one of two iiXed contacts is adapted to be oscillated thereon by the reciprocation of'said actuating member for opening and closing a circuit through saidr fixed contacts.

In the preferred embodiment of the invention, the actuating member is in the form of a push bar having a centrally disposed, peaked cam portion, which engages a switch member in the form of an elongated plate for holding it against a resilient portion of a fixed contact, which portion operates as a spring fulcrum, so that when the peaked cam is moved from one side of the fulcrum to the other, the switch plate is oscilla-ted on the resilient fulcrum either to close or to open the circuit by engagement with or disengagement from the other iixed contact.

One of the important features of my invention resides in the means provided for retarding the engagement or disengagement of the switch plate with or from the otherxed contact until the peaked cam of the push bar in its reciprocation is moved a .denite distancebe-yond the fulcrum. In the preferred` form'of this means,the,actuat ing` member isprovided with--a second cam on one side'of thepeaked cam, which-second cam has laterally projecting portions for .affording inner and outer c-am surfaces; and the tail portion of the switch member is recessed to t over this second cam and is provided with inwardly turned ears adapted to ride on one or the other ofthe outer orinner cam surfacesin order to hold the switch member from engagement with or disengagement from the other fixed contact, until the peaked cam of thepush bar .in its reciprocation has passed a deiinite. distance beyond the fulcrum, so increasing the lever arm Ithroughwhich the spring pressure acts when .the switch plate is released, thus causingit to move with a quick snap action. The switch plate is made of resilient material having spring qualities, so that when bent, it will return to its original straight form, and, by retarding its operation in the manner stated, a very rapid `movement of the switch member isv produced when it is released by the. second cam for engagement with or vdisengagement from the other contact. The quick snap action of the switch member thus produced shortens to a minimum the time duringwhich arcing may occur, and, thereby, reduces the arcing to a minimum. The elimination of undue arcing extends the life of the switch and permits its use in circuits of high voltage.

In the accompanying drawing showing one form of the invention, Figure l is a central, vertical, sectional view, partly in elevation, of a lamp socket of well-knownvform, equipped with a push button switch, constructed and adapted to be operated in accordance with my invention;

Fig. 2 is a transverse sectional View of the same on line 2-2`in Figure 1, looking upwardly,"

Fig. V3 is a central, sectional view online 3-3 in Figure2 lof the'insulating body, switch structure, and a portion of the lamp receiving screw shell',y the switch parts lbeing shown in sideV elevation and in open position; y

Figl iy is a view similar to Figure 3, but showing the switch member in retarded position just before it is snapped into closed position; l

Fig. 5 is a View similarfto Figure 3, but showing the switch in closed position, the switch member and its supporting contactl being shown, however, in longitudinal section;

Fig. 6y is aview `similar to Figure 5, but showing the switch member in retarded position just before it is released to be snapped into open position;

Fig. 7 is a view similar to Figure 5, showing the switch in open position;

Fig. 8 is a view in perspective of the insulating body in reversed position to disclose the switch chamber;

Fig. 9 is a perspective view of the center lamp contact;

Fig. 10 is a similar view of the switch member; and

Fig. 11 is a view in perspective of the push bar'.

In the drawing, I have shown the switch of my invention as being adapted for use in an electric lamp socket, but this is merely forthe purpose of illustrating the invention, since it is susceptible of use in other environments and for other purposes, and the invention is not' to bel limited to any particular use. y

Referring to the drawing, I5 indicates an insulating body of porcelain or other suitable insulating material in the form of a circular block having parallel top and bottom faces and adapted for use as an insulating body for a lamp socket. The body I5 is provided with a switch chamber I6 in the. form of a relatively `narrow diametrical recess opening out the' bottom face I1 and opposite sides of the body and having parallel walls and an inner end curved in crosssection. The form of the insulating body may be changed, however, to suit the particular use for which the switch is designed.

To the bottom face of the insulating body is fastened by screws I8 and I9 an insulating disk 20 and a lamp receiving screw shell 2I, the disk serving to close the switch chamber on the bottom face of the insulating body and to insulate the screw shell from the switch parts. The end of the shell which engages the disk is open, but

has opposite inwardly turned ears bored to re ceive the screws I8 and I9. The insulating body is provided with a longitudinal bore 22 (Fig. 8) for receiving the shank of the screw I9 (Fig. 1), which bore opens into a slot 23 opening out the top face of the insulating body. r In this slot is a plate 24 having its lower end provided with threaded bifurcations for meshing with the threaded shank of the screw I 9 to hold it in fastening position. The side of the body I5 is recessed at 25 to expose the upper end of the plate for mounting therein a binding screw 26, to which may be attache'd a lead wire 21. The plate 24 serves as the shell terminal in the lamp circuit. The other screw I8 is mounted in a similar bore 29 (Fig. 8) and is locked therein by the use of a bifurcated plate (not shown) similar in form to the plate 24 but smaller, 4which is positioned in a slot (not shown) opening out the top face of the body I 5.

Mounted in the chamber I6 is a switch mechanism for controlling a circuit between two fixed contacts 30 and 3I. 'I'he contact 30 (Fig. 9) is mounted in an olf-center slot 32 in the insulating body 20, and one portion of the, contact lies over the outer face of the disk`for providing a central lamp contact 33 within the screw shell; and the other portion lies over the inner face of the disk, having its free end 34 positioned approximately in the center ofthe switch chamber. This latter portion of the contact 30, after is passes through the slot 32, is turned in an outward direction in engagement with the face of the disk and then turned reversely so that the free end projects into the center of the chamber and serves as a resilient end hinged on the bend 35.

The other contact 3I, at its butt end, is fastened in a recess 36 (Fig. 2) in the bottom face of the insulating body by a screw 31, and its free end lies across the switch chamber in engagement with the inner face of the disk 20. I'he screw 31, which fastens the contact to the insulatingv body, is mounted in a longitudinal bore inthe `ody'and its threaded end meshes with the threaded bifurcations of a plate 38 mounted in a slot 39 opening out of the top face of the body. 'I'hs plate 38 serves to hold the screw fin fastened position and also serves as a contact the other lead wire 42 (Fig. 1) of the circuit.' "I'his construction is shown in dotted lines in Figs. 5, 6 and 7 of the drawing.

The switch mechanism comprises a switch member'45 and an actuating member 46. The switch'member is in the form of an elongated plate having one end .49 bent at a slight angle for adapting it for flat engagement with the contact 3l, and its other end is provided with a central, longitudinal'recess 50 opening out the end between two inwardly turned ears 53. The actuating member, which is preferably molded in one piece from suitable plastic material, is in the form of a push bar comprising a central peaked cam 55 of block form and two end portions 56 and 51 in the form of push buttons. On one side of the peaked cam 55, the push button 56 is cut away to permit the formation of a secondary cam 58 `consisting of a longitudinally projecting n carrying a pair of laterally projecting ears triangular in cross-section. 'I'he outer oblique and the inner faces of these ears act as cam surfaces.

These two members are mounted loosely in the switch chamber vwith the push bar in engagement with theinner, curved, end wall of the chamber and the switch plate intermediate the spring end 34 of the contact 30 and the peaked cam 55 of the push bar. vThe switch plate is thereby held by the peaked cam balanced upon the contact end 34 which serves as a spring fulcrum` for selectively oscillating the switch plate thereon when the peaked cam is moved from one side to the other side of the fulcrum in the reciprocation of the push bar. For limiting the reciprocation of the push bar. there is formed on the side walls and inner end of the switch chamber,` a continuous, projecting rib 60, and this rib projects in between the push buttons into loose engagement with the peaked cam block to act as a stop for limiting the reciprocation of the push bar. To hold the switch plate against longitudinal movement, its opposite sides are provided with recesses 62 into which the rib 60 projects loosely on each side. Although loosely mounted in the switch chamber, these two parts are held locked therein when the switch is assembled by the continuous rib.

In Figure 1 of the drawing, the foregoing parts are shown enclosed in a casing of ordinary and well-known construction, comprising a shell 65 and cap 66. The shell, at its top end, is provided with longitudinal slots 61 adapted to receive the projecting push buttons when the insulating body assembly is mounted in the casing. A cylinder 68 of insulating material is interposed between the shell and the insulating body assembly for insulating the latter from the shell, which is generally metallic.` The upper end of the shell is closed by the cap detachably mountedV thereon.

The operation of the switch mechanism is very simple. In Figure 3 of the drawing, the switch is shown in open position, with the push bar'at the extreme left. To operate the switch from this position, the push button isi-pressed inwardly, and as the peaked cam 55 passes over the fulcrum 34, the switch plate 45 is oscillated into the position shown in Figure 4. In the movement of the push bar thus far, the peaked cam has passed over the fulcrum, depressing it toward the disk 20, and has passed a denite distance beyond the fulcrum to the right, .but has not completed its full movement, In this position, the end 49 of the switch plate is held suiiciently far from the contact 3l to prevent arcing by the engagement of the ears 53 with the outer oblique cam surface of the cam 58. The completion of the movement from left to right of the push bar permits'the ears to slide orf the oblique surface of the secondary cam and that end of the switch to snap into the position shown in Figure 5, where it engages the straight shoulders of the cut-out portion of the push button 56 inside the cam; and, in this position, the end 49 of the switch plate makes a close, efficient engagement with the contact 3i. This final movement of the switch plate to close the circuit does not occur until after the peaked cam has passed a definite distance beyond the fulcrum, and the pressures exerted on the switch plate by the spring end of the contact 30 in an upward direction and by the cam 55 in a downward direction, brings about an exceedingly rapid snap action into closed position when the ears slip off the oblique cam surface.

To open the switch from the position shown in Figure 5, the push button 5l is pushed inwardly from right to left, and, in therst part of this movement, the peaked cam moves across and beyond the fulcrum a denite distance to the left, and the ears 53 on the switch plate engage the inner cam surface of the secondary cam which holds that end against outward movement. As a result, the peaked cam brings about a slight bending of the switch plate, as shown in Figure 6, and holds the end 49 in close engagement with the contact 3|; and this continues until the peaked cam has moved a denite distance to the left of the fulcrum. As the push bar completes its movement to the left, the rear end of the switch plate is released from the inner cam surface, an'd, due to the pressures in opposite directions exerted by the spring fulcrum and the cam 55, the plate is oscillated on the fulcrum in a very rapid, snap action into the position shown in Figure '7. This snap action is so rapid that any arcing which may ensue from the separation of the switch plate from the contact 3l is reduced to a minimum, so that the arcing is not appreciable. One factor in producing this snap action in opening the circuit is the increased tension of the spring portion of the contact 35 and of the switch plate as the cam 55 rides up the switch plate beyond its fulcrum, and another factor is the increased spacing between the engagement of the cam 55 on the switch plate and the fulcrum 34 which increases the effective lever arm through which the spring action is exerted to rock the switch plate out of engagement with the contact 3l in closing the circuit. While the lever arm increases as the actuator moves from the position of Figure 4 to that of Figure 5, the spring tension slightly decreases since the cam 55 is moving downwardly with reference to the switchplate. 4'Since' arcing is more likely on breaking the switch 'than on making it, the quick and increased magnitude of the snap motion is utilized in breaking rather than making the/circuit.

It will be observed that one of the features of my invention resides in the molding 'of the actuating member in one piece from any suitable plastic composition which will produce a structure which is hard and durable. I-Ieretofore, actuating members in the form of push bars have involved a combination of elements, somemetallic and others of insulating material, necessitating a number of operations for the production of the push bars which have materially increased the cost of these parts. By molding, the cost is greatly reduced and at the same time actuating members are produced which are uniform and accurate in shape and dimensions. Such accuracy and low cost are important considerations in devices of this character.

It may also be pointed out that my switch is of very simple construction employing a very small number of parts which conduces to a low cost of construction and assembly.

It is to be understood that my invention is not to be limited to the form herein shown and described since it may be embodied in various other forms within the purview of the following claims.

WhatI claim is:

1. A switch comprising a pair of fixed contacts, one of said contacts having av free end adapted to serve as a `spring iulcrum, a switch plate for controlling a circuit between said contacts, a push bar having a peaked cam for holding said switch plate in engagement with said iulcrum and for oscillating said plate thereon into and out of engagement with saidother contact when said push bar is reciprocated, said push bar being provided with means for retarding the operation of said switch plate until said peaked cam has passed a deiinite distance beyond said fulcrum.

2. A switch comprising a pair of fixed` contacts, one of said contacts having a free end adapted to serve as a spring fulcrum, an elongated resilient switch plate for rcontrolling a circuit between said contacts, a push bar having a peaked cam for holding said switch plate in engagement with said fulcrum and for oscillating said plate thereon into and out of engagement with said other contact when said push bar is reciprocated, said push bar being provided with means for retarding the operation of said switch plate until said peaked cam has passed a definite distance beyond said fulcrum.

3. A switch comprising a pair of fix-ed contacts, one of said contacts having a free end adapted to serve as a lspring fulcrum, a switch plate for controlling a circuit between said contacts, a push bar having a peaked cam for holding said switch plate in engagement with said fulcrum and for oscillating said plate thereon into and out of engagement with said other contact when said push bar is reciprocated, said push bar being provided with cam means for retarding the operation of said switch plate until sai'd peaked cam has passed a definite distance beyond said 'fulcrum.

4. A switch comprising a pair of xed contacts, one of said contacts lhaving a free end adapted to serve as a spring fulcr'um, a switch plate `for controlling a circuit between said contacts, a .push bar having a peaked cam for holding said switch plate in engagement with said fulcrum and for oscillating said plate thereon into and out of engagement with said other lcontact when said push bar is reciprocated, said push bar beingprovided with a secondary cam having outer and inner cam surfaces for retarding the operation of said switch plate until said peaked cam has passed a denite dis-tance beyond said fulcrum.

5. A switch comprising a pair of xed contacts, one of said contacts having afree end adapted to serve as a spring fulcrum, a switch plate for controlling a circuit between said contacts, means for preventing longitudinal movement of said plate, a push bar having a peaked cam for hold-l ing said switch member in engagement with said fulcrum and for oscillating said member thereon into and out of engagement with said other contact when said push bar is reciprocated, said push bar being provided with means for producing a rapid snap action of said switch member by retarding its operation until said peaked cam in the reciprocation of said push bar has passed a denite distance beyond said fulcrum.

6. A switch comprising a pair of Xed contacts, one of said cont-acts having Va free end adapted to serve as a spring fu1crum, a switch plate for controlling a circuit between said contacts, a push bar having a peaked cam for holding said switch. plate in engagement with said fulcrum and for oscillating said plate thereon into and out of engagement with said other contact when sa'id push bar is reciprocated, said push bar being provided with means operating on the tail end of said switch plate for producing a rapid snap action thereof by retarding the engagement with or disengagement from said other contact of its other end until said peaked cam in .the reciprocation of said push bar has .passed a definite distance beyond said fulcrum.

7. A switch comprising a pair of xed contacts, one of said contacts having a free end adapted to serve as a spring fulcrum, a switch plate having its forward end adapted for engagement with said other contact for controlling a circuit between said contacts and having its tail end provided with an open recess and a pair of inwardly projecting ears, a push bar having a peaked cam for holding said switch member in engagement with said fulcrum and for oscillating said member thereon into and out of engagement with said contact when said push bar is reciprocated, said push bar being provided with a secondary cam adapted to cooperate with the tail end of said switch for ret-arding its engagement with or disengagement from said other fixed Contact untl said push bar has passed a deiinite distance beyond said fulcrum.

8. A switch comprising a pair of xed `contacts, one of said contacts having a free end adapted to serve as a spring fulcrum, a switch plate having its forward end adapted for engagement with said other contact for controlling a circuit between said contacts and having its tail end provided with an open recess and Ia pair of inwardly projecting ears, a push bar having a peaked cam for holding said switch member in engagement with said fulcrum and for oscillatingsaid member Vthereon into and out of engagement with said contact when said push bar is reciprocated, said push bar being provided with a secondary cam having inner and outer cam surfaces adapted to cooperate with said ears on said switch for retarding its engagement with or disengagement from said other xed contact until said push| bar has passed a deiinite distance beyond said fulcrum.V

9; An electric switch comprising an insulating bodyrecessed to form a switch chamber, a xed contact mounted in said chamber, a central lamp contact having one end `projecting into said chamber and adapted to serve as a spring fulcrum, a switch plate supported centrally for oscillation on the end of said spring member and an actuator mounted in said chamber and having a peaked cam in engagement with said switch plate for throwing it into or out of engagement with said fixed contact when said actuator is reciprocated, said actuator being provided with means for preventing the operation of said switch plate to close or open the circuit until after said peaked cam has passed a denite distance beyond said fulcrum.

10. An electric switch comprising an insulating body recessed to form a switch chamber, a fixed contact mounted in said chamber, a central lamp contact having one end projecting into said chamber and adapted to serve .as a spring fulcrum, a switch plate supported for oscillation onj the end of said fulcrum, and an actuator mounted in said chamber and having a peaked camin engagement'withl said switch plate for throwing it into or out of engagement with said xed contact when said actuator is reciprocated, said .actuator being provided with a secondary cam adapted for engagement with the tail end of said plate to retard its operation to close or to open the circuit until after said peaked cam has passed a denite distance beyond said fulcrum.

11. An electric switch comprising an insulating body recessed to-form a switch chamber, a xed contact mounted in said chamber, a central lamp contact having one end projecting into said chamber .and adapted to serve as a spring fulcrum, a switch plate supported centrally for oscillation on the end of said fulcrum and an actuator mounted in said chamber and having a peaked cam in engagement with said switch plate for throwing it into or out of engagement with said xed contact when said actuator is reciprocated, said actuator being provided with a secondary cam having inner and outer cam surfacesand said plate having its tail end provided with ears adapted to ride on said cam surfaces for retarding the operation of said switch plate to close or open the circuit until after said peaked cam has passed a definite distance beyond said fulcrum.

12. In a switch of the character described, an actuating member in the form of a one piece push bar molded from suitable material and comprising `a central peaked cam 'block intermediate two push button end portions and a secondary cam adjacentA one side of said peaked cam and having inner and outer cam surfaces, said push `button portions having' their inner ends projecting laterally beyond the sides of said cam block to serve as stops to limit the reciprocation of said push bar when in use.

13. A device of the class described comprising a pair of xed contacts, one of saidcontacts having a spring portion, spring snap action switch means of which said spring portion is a part for controlling a circuit through said contacts, means for preventing motion of said switch means, and a control member manually movable in one or the other direction and having means to rst condition said snap action for operation to break the circuit and including means to then Uli said plate tending to cause pivotal motion thereof to make or break the circuit, said pressure effectively increasing as said control member continues its motion beyond said fulcrum, and means for preventing such selective pivotal motion releasablewhen said effective pressure has been increased by a substantial amount.

ARTHUR A. JOHNSON.

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