US2156902A - Electric switch - Google Patents

Description

May 2, 1939.

R. POPP ELECTRIC SWITCH Filed Sept. 9, 1955 Patented May Z, 1939 PATENT OFFICE ELECTRIC SWITCH Rudolf Popp, Valparaiso, Ind., assignor to McGill Manufacturing Company, Valparaiso, Ind., a

corporation of Indiana Application September 9, 1935, Serial No. 39,743

9 Claims.

My invention relates in general to electrical switches and more in particular to a high capacity pull chain switch, as an improvement over the structure of my Patent No. 1,879,822.

Ordinarily the current supply in a house, ofce or the like requires a small capacity pull chain switch designed for approximately three to six amperes. However, there is a rather extended need for a higher capacity switch for an eight to ten ampere line. rPhe switches designed for this purpose in use at the present time are heavy, bulky, and very expensive, particularly in comparison to the small capacity switches. In operating the high capacity switch it is necessary to provide positive contact pressure between the bridging contact member and stationary contacts, and also to design a Switch to guard against excessive arcing which, in such a high current, might easily short across the switch, burning out the switch and possibly causing considerable damage in the line, or even a lire.

It is an object of my invention to provide an improved high capacity electrical pull chain switch.

A further object is to provide a switch mechanism including contact members which will effect a clean, positive Contact in making and breaking a circuit through the switch.

A still further object is to provide a switch constructed to prevent excessive arcing and the mechanism insulated to protect the switch against short-circuiting and nre.

Another object is to provide such a high capacity switch which is compact, sturdy and inexpensive.

Other objects and advantages will be apparent from the following description taken with the drawing, in which:

Fig. l is a top plan view of the switch mechanism removed from the covering housing.

Fig. 2 is a cross-sectional View along the line 2--2 of Fig. 1.

Fig. 3 is a sectional view along the line 3--3 of Fig. 2.

Fig. 4 is a perspective View of the stationary contact blade of the switch of my invention; and

Fig. 5 is an exploded view of the terminal post and insulator therefor.

In practicing my invention` I provide a switch mechanism including a pair of spaced-apart parallel insulating plates having a pair of combination terminal posts and spacers on the outside thereof, a heavy yet resilient stationary contact on each of said posts including a pair of comparatively thin spring leaves riveted together and (Cl. ZOU-64) mounted on a post with a heavier contact portion rigidly carried on said spring leaves for engaging a bridging contact member rotated between said contacts by an actuator which in turn is operated by a reciprocating pawl of the type disclosed in my Patent No. 1,879,822 noted above. I further provide a removable insulating plate carried on the inside of each of said terminal posts` and retained against the post by the terminal screw extending through an aperture in said insulating plate, and a pair of ears extending upwardly and downwardly from the body portion thereof to engage behind corresponding shoulders in the upper and lower insulating plates for the switch mechanism. An enlarged insulating disc is carried between the bridging contact member and reciprocating pawl for preventing any possible arcing which might occur at the Contact blades from jumping to the remainder of the switch mechanism.

Referring now to the drawing, I provide a switch mechanism for mounting in a suitable housing, which mechanism is mounted in a frame including a pair of insulating covers I and II spaced apart and retained in fixed position by terminal posts I 2 and I3. A switch mounting bracket I4 such as that shown in the patent mentioned above, has lugs I6 extending upwardly and downwardly through corresponding apertures in said covers as shown in Fig. l. The terminal posts I2 and I3 are identical and constructed in accordance with the illustration of Fig. which, for convenience, I will describe as post I2. This includes integral lugs I'I on the top and bottom extending through corresponding apertures in the insulating covers as can be understood from Figs. 1 and 2, which together with lugs I6 may be upset upon the nal assembly to hold the frame in xed position.

An actuator I8 such as shown in the above patent is journalled in the frame plates I9 and I! with a ratchet wheel I9 rigidly secured thereto, to be carried in elongated slots 2l in a U- shaped pawl member 22. This pawl in turn is spring mounted in the member I4 and is moved forwardly and backwardly by a universal lever 23. The movement of the actuator I8 in turn causes the rotation of a disc 24 formed of insulating material and carrying a spider-like bridging contact member 2li with integral Contact arms mounted against ratchet teeth 2'I as shown particularly in Figs. 2 and 3.

The stationary contact blades shown in Patent No. 1,879,822 and those ordinarily used in the present day switches, do not aiord such a posi- Cil tive contact with the bridging contact member as to preclude excessive arcing in a high amperage line with the resulting serious damage to the switch and possible re in the vicinity of the switch mounting. In a high capacity switch there are other factors to be considered in eliminating arcing, Such as a sharp make and break action and a wiping action on the contact blades so as to maintain a bright, clean surface. As previously mentioned, the prior art has tried to overcome these difficulties in a large, cumbersome and expensive switch. In the commercial embodiment of my invention, however, I have very satisfactorily eliminated danger of excessive arcing or in fact any appreciable arcing at all in the structure including the two stationary contact members 28 and 29. These members are identical but simply mounted in opposite position as illustrated in Fig. 4.

Each contact member includes a pair of relatively thin leaves 3| and 32 lying together in a substantially laminated form and having a mounting portion 33 with apertures 34 for mounting on the terminal posts I2 and I3, as will be hereinafter described. The leaves 3| and 32 are stamped from sheets or strips of a resilient metal conductor and when assembled as described, provide a very compact, sturdy member, with considerably greater life than a single leaf as heavy as the laminated member. Each leaf includes a curved arm portion 36 in which the greater portion of the bending and spring motion of the contact member is centered. The laminated member provides the necessary resiliency, and exerts a continued greater pressure on the contact mechanism, without the danger of crystallizing with use as has, been found to occur in the heavy one-piece arms of the prior art. In this connection I aline the leaves and obtain a tight engagement between the same upon the assembly thereof, and then with the mounting portion rmly pressed against a terminal post, secure the leaves thereto by relatively soit rivets 35. The apertures 34 are provided slightly larger than the shank of the rivets 35, and by employing a soft metal rivet I am able to accommodate the same to the aperture 34 and extend through an aperture 45 in the post, even though two corresponding apertures 34 might be slightly out of alinement.

The arm portion 26 has an enlarged end, apertured to receive a rivet 31 for securing the contact blade 38 itself to the arm. The blade is arcuate in shape and corresponds substantially with one of the contact portions of the bridging Contact member 26 through which it makes the necessary electrical connection. The blade is formed to a iiange 39 at right angles thereto, and the flange ts over the end of the arm 35 to insure against rotary movement of the blade about the rivet 31. Satisfactory performance is obtained with the blade 38 approximately twice as heavy as each one of the leaves 3l and 32, and more rigid. The metal is stiff enough to retain its shape under the rather heavy spring pressure of the arm 36. This combination of the loi-part member 28 provides a rather heavy snapping action between the bridging contact member and stationary contact to make a sharp electrical connection and keep the engaging surfaces of the two members clean so as to reduce arcing to a minimum.

In insulating the contact mechanism of the switch from the remainder of the switch, and particularly to prevent short circuiting between the terminal posts, should arcing occur, I provide removable insulating plates 4I and 42 for fitting on the inside of the terminal posts I2 and I3 respectively, adjacent the spot where arcing would occur. I use any desirable relatively stiif insulating fiber punched out in the form shown in Fig. 5, with a plate portion corresponding to a body portion of the terminal post, and upwardly and downwardly extending ears 42a tting into corresponding notches 43 in the upper and lower fra-me plates I0 and II.

An aperture 44 is provided corresponding with the threaded aperture 46 in the terminal post, but slightly smaller than the aperture 46 so that the insulating plate may be forced over a terminal screw 4l and be frictionally retained thereby against the inside of each of the posts I2 and I3. It is recognized, however, that I do not depend solely upon the terminal screw 4'? to retain the insulating plate in position, inasmuch as the ears 2 extending into the notches as described are retained as shown in Fig. 2. The shoulders IEB on the insulating plates engage the inside surface of the frame plates to also cooperate in positioning the plates 4I and 42.

The contact mechanism is further insulated by a removable circular insulating disc 49 centered on the actuator and axis I8, and carried on the toothed disc 2l. The disc 49 is large enough to extend substantially between each of the insulating plates 4I and 42. This disc in combination with the insulating plates 4I and 42 provides in effect a spark-proof cover for the contact portions of the switch mechanism.

Although I have described and illustrated my invention in its preferred embodiment, it is understood that I am not limited thereby, but limit my invention only by the scope of the appended claims.

I claim:

l. A high capacity switch mechanism comprising a pair of frame plates spaced apart and supported on a pair of at metal terminal plates, a multi-leaf stationary contact member mounted on each terminal plate and having a portion extending inwardly to lie between said frame plates, a bridging contact member rotatably mounted between the contacts, and an insulating member corresponding substantially with the shape of a terminal plate removably mounted on the inside surface of each terminal plate adjacent the point of contact between the bridging contact member and stationary contact to insulate each metal terminal plate at the inside thereof.

2. A switch mechanism as described in claim l, with each of said insulating members including a body portion corresponding with the body portion of the terminal plate and ears extending upwardly and downwardly from the body portion to fit into corresponding notches in the frame plates to retain the insulating member in position against said terminal plate.

3. A high capacity switch mechanism comprising a pair of frame plates spaced apart and supported on a pair of metal terminal plates, to provide an open frame for the movable switching mechanism, a stationary contact member rigidly mounted on each terminal plate and supported solely by said terminal plate and a bridging contact member rotatably mounted between said stationary contact members in said open frame, insulating means on the inside surface of each of said terminal plates adjacent the point of engagement between the bridging contact member and stationary contact, and an insulating disc on the top of the bridging contact member extending substantially between the insulating means to provide in effect a spark proof cover for the contact mechanism.

4. A switch mechanism as described in claim 3 with said insulating means comprising a flat plate having an apertured body portion corresponding with one of said terminal plates for mounting on the inside of each of said terminal plates, a terminal screw for each terminal plate, with said aperture in each of said insulating plates smaller than a corresponding terminal screw whereby said insulating plate is retained on said terminal plate upon forcing said aperture over said screw.

5. A switch mechanism as described in claim 3 including a terminal screw in each terminal plate, and with said insulating means including a plurality of ilat insulating plates, each apertured to fit over a corresponding terminal screw and be frictionally retained thereon against the terminal plate for said screw, and having downwardly and upwardly extending ears fitting into corresponding notches in the frame plates of said switch mechanism.

6. A switch mechanism comprising a pair of frame plates and terminal posts for supporting said plates to provide an open frame for the movable switching mechanism, a bi-portion stationary contact mounted on each post, comprising a laminated spring portion and a one-piece spring blade contact arm, a bridging contact member rotatably mounted between said stationary contacts and insulating means adjacent the point of contact between each stationary contact and the bridging contact member to provide in effect a spark-proof covering over said contact mechanism in said open frame, said means including an insulating plate on the inside of each terminal post and an insulating disc carried on top of said bridging contact member of greater diameter than the diameter of said bridging contact member.

7. In a high capacity electric switch, a pair of frame plates with each plate having a cutout portion adjacent the edge at two oppositely disposed points thereon, a pair of terminal plates for supporting and spacing apart said frame plates and engaging said frame plates adjacent said cut-out portions, a stationary contact on each terminal plate, bridging contactmeans rotatable between said stationary contacts, and an insulatmg plate for positioning against the inside surface of each terminal plate and corresponding substantially in size therewith, each insulating plate having an ear extending upwardly and one downwardly therefrom to t in the corresponding cut-out portions of said frame plates to retain said insulating plates against said terminal plates.

8. A high capacity electric switch mechanism including in combination a pair of frame discs, a bridging contact rotor mounted between said discs, a plurality of terminal units between said discs and within the contines of the frame defined by said discs, and a contact assembly rigidly secured on each terminal unit and lying within said frame for connection between the contact rotor and its corresponding terminal unit, each of said contact assemblies comprising a pair of similar spring leaves nested upon one another and with the two together rigidly secured at one end in nested relationship upon a terminal unit and floating free of a stationary mounting at the other end, a single spring leaf non-rotatably secured to said pair of leaves at their floating end and doubling back on the pair-leafed portion with the free end thereof lying opposite the terminal unit and in position for engagement with the contact rotor.

9. A high capacity electric switch mechanism comprising in combination, an insulating frame including a pair of spaced apart discs, a contact rotor and a terminal post between said ldiscs and within said frame, a stationary brush assembly for making electrical connection between the terminal post and contact rotor, said assembly comprising a laminated spring unit having a ilat mounting portion for rigid mounting on said terminal post and extending laterally within the confines of the frame in a substantially arcuate-shaped arm to a non-mounted end, a single spring member secured to said non-mounted end against rotation with respect thereto and extending from said end in an arcuate shape doubled back on said laminated spring arm to a non-secured end, with such latter end of said single spring member adapted for engagement with said contact rotor, and with said laminations of said unit fixed with respect to one another at each end but exing with respect to one another intermediate the ends and acting with said spring member to provide a sharp break and make between the stationary brush and the contact rotor,

RUDOLF POPP.

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