US1928638A - Electric switch - Google Patents

Description

Oct. 3, 1933. c, E. AVERY ELECTRIC SWITCH Filed July 22, 1929 37 mnntot dtozmq 5 Patented Oct. 3, 1933 UNITED STATES PATENT OFFICE ELECTRIC SWITCH Application July 22, 1929. Serial No. 379,954

4 Claims.

'I'his invention relates to electrical switches, and has for an object to provide a greatly simpliiied four way switch construction.

It is also an object of this invention to provide an improved construction of stationary and movable contacts in a switch which will give a better and more reliable contact at or immediately after closing a circuit when the current is the greatest to prevent undue sparking and injury to the contacts at this time.

It is a further object of this invention to provide an improved switch element which may be more easily constructed and with much less liability of short circuiting than in similar devices in the prior art, and to provide a corresponding contact element which will make a more positive contact than in the prior art devices.

With the foregoing and other objects in view, the invention consists in certain novel features oi construction and arrangementof parts as will be more fully described in connection with the -accompanaying drawing.

In this drawing,

Fig. 1 is a top plan view of a switch according to this invention showing a four way construction.

Fig. 2 is a longitudinal section thereof substantially on line 2-2 of Fig. 1.

Fig. 3 is a transverse section substantially on aoline 3-3 o1' Fig. 2.

Fig. 4 is a detail section substantially on line 4--4 of Fig. 1.

Fig. 5 is a side elevation of the two cross over supports for one set of contacts and shown in separated relation.

Fig. 6 is a`section similar to Fig. 3 showing how the improved cross over arrangement can be used with the old type of male stationary contacts.

Fig. 'l is a detail section substantially on line 4o '1 -'l Fig. 6, and

Fig. 8 is a top plan view of one side of a switch using the contacts of Fig. 6 and showing the female type of movable contact element.

The embodiment of my invention shown comprises an insulating body member 15 in the present case molded in one piece, with a pocket 16 in which the switch mechanism is mounted. I do not, however, wish to be limited to this specific construction of the body member as any of the usual forms may be employed, as for instance, where the body is made in two sections secured together. The switch mechanism is secured to the bottom wall of the pocket by means of suitable screws 17 threaded into the base 18 of the bracket 19, the bracket in the present case being (Cl. 20o-166) substantially U-shaped with spaced upright side members 20. Mounted in each side member 20 is a pivot 21 carrying a substantially U-shaped support 22 for either one or two switch members 23, there being two in the present showing so mounted on opposite sides of the frame 20. It

is carried to swing with the support on the pivot pins, and is insulated from the support by suitable fibre washers 24.

Mounted between the arms 20 of the bracket c5 and projecting through an opening in support 22 is a T-shaped rocker 26, shown in partly dotted outline in Fig. 2. About the stem of the rocker 26 is a coil spring 27, forming a part of a load and nre toggle switch device. In the top of the rocker 26 is a notch 28 in which projects the shoulder 29 of an oscillating lever 30 to which is affixed the toggle handle 31. Lever 30 is pivoted to bracket 20 at 32, and when handle 31 is pivoted, it moves rocker 26, compressing spring 27 until the 75 rocker is past dead center, whereupon the spring expands, completing the oscillation of the rocker and throwing the switch member 23. Although a particular toggle switch is described, the invention is not limited to use with this switch, but any other toggle switch or push button switch may be used.

The switch member 23 is a male switch element as at 33, and is beveled on its entering side as at 34. Shoulders 35 are provided by the body mem- 85 ber 15 to which are afxed the lead connections 36 by means of screws 37, while binding screws 38 provide means for attaching lead wires thereto. At the opposite end of the body block are mounted lead connections 58 and 59 carrying 90 binding screws 60 and secured to the body by screws 62. Attachedto the lead connections 36 are contacts. At one end of body l5 the lead connections 36 have depending straps 39, and have upper contacts 40 and lower contacts 41 at each 95 end of strap 39. These contacts comprise U- shaped spring member 42, preferably oi sheet metal, having inturned prongs 43, thereby providing female contact members, and flaring wings 44 on each contact provide a more certain en- 100 trance for the male switch element 23. This movable male switch element and stationary, flared wing female contact have a material advantage when the circuit is first closed over the old type of movable switch element and stationary contact.

A common construction of switch at the present time is to make the stationary contacts the male elements and construct the movable contact of two substantially at sheet metal spring members arranged side by side and insulated from the rocking support. When the movable switch element is shifted to engage the stationary contacts insuchaconstructionthespring platesofthe movable element are separated by the stationary contact moving in between them, and due to the length of the movable contact plates, their construction and means of mounting there is considerable lateral vibration of these plates at this time because the contacts move to closed position with a very rapid movement. For this reason there is not a good and reliable surface contact or engagement between the stationary and movable contacts when the circuit is nrst closed and for a short time immediately thereafter. This is because the vibration of the contacts breaks the continuity of the circuit. Furthermore, this happens at the time of greatest load and for the period when the greatest current is flowing. Therefore, considerable trouble has been experienced with these switches, particularly in the contacts buming and deteriorating and soon failing,andalso intheiirehamrd. This isparticularly true where the'switch is used in circuits employing the modern gas or nitrogen illled lamps. It is a characteristic of these lamps that when cold and first lighted they permit a very largecurrenttnpassoftenashighasten times the normal current required after they become heated. Thus, for example, in a circuit which normally requires ten amperes the current may beashighasonehundredamperes fortheshort time immediately after the circuit is clod while the lamps are heating up. While this heating requires only a short time, usually only a fractionofasecond,stilltheheavyloedandlarge current have a very injurious effect on the switch contacts, actually melting portions of their surfaces and causing sparks of molten metal when the switch is closed. with my new construction and arrangement of switch contacts shown I have greatly reduced and practically over-come this dimculty. Actual tests have shown that with my new contacts there is much less sparking at the contact surfaces when the switch is closed than intheoldtypeofswitcheswiththesameload and conditions, and that the switch can be operated much longer before failing. Ihere is also agreaterdangerintheoldswiichesofthesparks themovableswitchelemmtismerelyai'iatbar andthestationaryorfemalecontactsareonone piece. AlsoaswillbeseeninFig.1theouterarms 42areofgreaterlengthtbantheinnerarms43, si)` that these different lengths give dierent of vibration which tend to neutralize or otherendofthebody ltheleadconhave criss-crossed depending respectively so that the lower 52 and bushing 52' about the rivet. The straps 45 and 46 are preferably in one piece with the members 58 and 59 respectively, and these members have integral ears 83 and 64 extending laterally therefrom to which the upper contacta 4l and 50 are respectively connected.

When assembled, the cover 53 is held on the body 15 by the strap 54 which is screwed'thereto as at 55. Btrap 54 then provides means for holding the whole mechanism to the wall outlet box (not shown) and face plate 56 may be secured thereto by means of screws 57.

As shown, the upper and lower contacts provide a four way switch, but it may easily be converted into a one-way. two-way or three-way switch 'by the omission of appropriate upper and/or lower contacts, and by appropriate wiring. Or the four-way switch shown may be used with three-way switches for controlling the same lamp from three different floors. With this arrangement the lamp may be controlled from any floor regardless of the position of the switch on the other doors. and if there are more than three floors it is merely necessary to add an additional four-way switch for each additional floor.

Prom the foregoing description it will be seen that the depending straps with their upper and lower contacts provide a construction which may be easily assembled in the insulating body, while the new construction and arrangement of the male switch and female contacts is a material improvement over the old constructions in length of service, reliability. and decreased fire hazard. It will also be apparent that the same body elementmaybeusedforswitchesofothertypes and hence the diiferent types may be inabodymembermadefromasinglemold, thereby greatly simplifying manufacture. lh Figs. 6 to 8 is shown how the cross over straps 65 and 56, corresponding to straps 45 and 45 respectively, and the means for mounting them can be used to carry straight male stationary contacts 67, 68, B9 and 70 corresponding to the female contacts 47, 48, 49 and 50 respectively. These male contacts are preferably stamped from sheet metal in one piece with their respective strapsandthen bent to theproperpositionfor use. With this type of stationary contact is ordinarily used a female movable contact comprising two thin metal spring plates 7l carried by the rocking support 22 and insulated therefrom. When the switch is closed the two plates of the movable contact engage the opposite sides of the stationary male contacts as indicated in Fig. 5.

lll

Thisistoshowthatthecrossoverstrapsandm theirmeansofmountinginthebodyarenot limited to use with the specific contact construction shown in Figs. l to 5.

As the cross over straps or connections 45 and 46areinonepi'ecewiththemembers58andm lll wardly thereof substantially at right angles thereto and comprising a strip of resilient sheet metal of substantially U-shape with the free ends of the side portions extending inwardly adjacent each other and in the same general direction as the side members, said free end portions converging slightly toward each other and being adapted to receive the male switch element between them, contacting ilrst at their extreme tips and lying fiat against the male element after it is fully entered.

2. In a snap switch including a rocking member operated for a quick closing action by means of a spring in which energy is first stored and then released to give the quick action, said member being a substantially flat bar mounted to rock in the plane ot the bar, a stationary contact comprising a strip of resilient sheet metal of substantially U-shape with the opposite side portions curved inwardly toward each other and extending toward the connecting bar portion and providing substantially ilat opposing surfaces, and said side portions extending in the general direction of the movable bar so that the bar will enter between said opposing surfaces laterally from one side.

3. In a snap switch including a rocking member operated for a quick closing action by means of a spring in which energy is first stored and then released to give the quick action, said member being a substantially flat bar mounted to rock in the plane of the bar and having its edge portions flattened adjacent its ends to provide wedge-like portions, a stationary contact to cooperate therewith comprising a strip of resilient sheet metal of somewhat toward each other so as to be nearer together adjacent their free ends than at the curved portions, and said rocking member adapted to have its wedge-like edge portion enter between said free ends of the free-end portions of the stationary contact.

4. In a snap switch including a rocking member operated for a quick closing action by means of a spring in which energy is first stored and then released to give the quick action, said member being a substantially flat bar mounted to rock in the place of the bar, a stationary contact to cooperate therewith comprising a strip of resilient sheet metal of substantially U-shape with the free ends of the opposite side portions curved inwardly toward each other and extending toward the connecting bar portion, said end portions extending in the general direction of the movable bar so that the bar will enter between them laterally from one side, said end portions including ilat sides arranged in opposing relation to engage the sides of said rocking bar and said portions also converging toward each other so as to be nearer together adjacent their free ends then at the curved portions to engage the bar ilrstat a distance from said curved portions.

CHARLES E. AVERY.

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