US2558739A - Box cover switch - Google Patents

Description

y 3, 1951 v. R. DESPARD 2,558,739

BOX COVER SWITCH I Filed Sept. 15, 1947 2 Sheets-Sheet 1 INVENTOR. VICTOR R. DESPj-KRD By wgzrgh ATTORNEYS July 3, 1951 V.-R. DESPARD 2,558,739

BOX COVER SWITCH INVENTOR. VICTOR R. "DESPBRD v BY F p QZ QM ATTORNEYS Patented July 3, 1951 OFFICE BOX COVER SWITCH Victor R. Despard, Syracuse, N. Y., assignor to Pass & Seymour, Inc., Syracuse, N. Y., a corporation of New York Application September 15, 1947, Serial No. 774,015

4 Claims.

This invention relates to electric snap switches, and more particularly to such snap switches incorporated in covers for junction boxes and the like.

It is a general object of the present invention to provide a novel and improved box cover switch wherein the switch mechanism operates in a plane parallel to the face of the box.

An important object of the invention comprises the combination of box cover and snap switch wherein substantially all of the switch is housed in the cover outside of the chamber of the box itself, leaving the whole interior of the box clear and free for the making of connections, splices and the like.

Another important object of the invention consists in the construction of the box cover and switch housing from one piece of molded plastic adapted to receive and hold the stationary contacts, the movable contact assembly and the operating lever and handle with a minimum of fastening elements and assembly procedure.

Still another important object of the invention consists in the arrangement of a central integral projection on the front face of the box cover for housing all of the switch parts, the operating toggle for the switch being arranged to extend through the lower wall of this projection and be largely protected by the latter from accidental bumping by moving objects which might tend to break the relatively fragile operating handle.

Among the important features of the invention may be enumerated the simple mounting means for the stationary contacts; the integral construction of the stationary contacts, connectors and terminals; the novel arrangement and mounting of the movable contact and snuffer assembly; the construction, assembly and mounting of the operating handle and spring carrier; and the arrangement of an internal cover and insulating member for holding a majority of the parts in their assembled position.

Other and further objects and features of the invention will be more apparent to those skilled in the art upon a consideration of the accompanying drawings and following specification wherein is disclosed a single exemplary embodiment of the invention, with the understanding that such changes and modifications may be made therein as fall within the scope of the appended claims without departing from the spirit of the invention.

In said drawings:

Fig. 1 is a front elevation of a box cover switch 2 adapted to be mounted on a standard 3%" junction or outlet box, the same being shown in full size;

Fig. 2 is a rear elevation, shown in double size, with the rear cover and insulating plate shown in dot-and-dash lines to illustrate the manner in which it holds the parts in assembled relationship, the switch being shown in one of its on positions;

Fig. 3 is a view similar to Fig. 2 but illustrating the switch operating handle moved almost to the dead center position and showing the positive kick off just cooperating and ready to insure positive throwing of the movable contact assembly;

Fig. 4 is a central vertical section taken on the substantially vertical line 4-4 of Fig. 3;

Fig. 5 is a view on an enlarged scale of the movable contact assembly shown without the snuffer plate; and

Fig. 6 is a perspective view of the movable contact and snufi'er carrier element prior to assembly with the contacts and snuffer.

Where snap switches have been combined with boxe covers heretofore, the cover has in most cases been metal to support a snap switch of the conventional wall type wherein the toggle extends through a slot in the plate and operates in a vertical or horizontal plane bisecting the box and the main body of the switch extended entirely within the chamber of the box. Since the principal purpose of junction boxes is to house the connections of a number of conductors and their splices, there has been some complaint that such switches seriously interfere with and curtail the amount of wiring and splicing which can be done in these boxes. To overcome this difficulty the present invention proposes an extremely shallow type of switch incorporated in a unitary housing and box cover wherein the plane of operation of the switch is vertical and parallel to the face of the box and no portion of the switch mechanism extends into the box. Several further advantages flow from this construction as will appear as the description proceeds.

Referring now to the drawings and first to Fig. 1, it will be seen that the invention comprises a switch housing or projection Ill formed integral with a box cover ll molded from plastic material. radial ribs l2 to provide stiffness and lightness. A circumferential bead l4 reinforces the edge and merges with bosses l5 perforated at [6 and countersunk from the front face at I! to accom- The back of the cover is reinforced by modate a pair of fastening screws for mounting on the ears of a standard 31/4" junction box.

As seen in Fig. 4 the projection 10 is substantially cylindrical in form with a pleasingly rounded outer end I8. For about one-half of its circumference it is surrounded at its junction with the plate H by a shoulder 20, which serves to house portions of the terminals. The circumferential wall of the projection I is radially slotted at the bottom as shown at 2| to permit the operating handle 22 to project downwardly where it moves close along the flat surface of the plate II, as seen in Figs. 1 and 4. A portion of the rounded surface [8 may be cut away as at 24 to the peculiar shape shown to expose off and on markings on the handle where desired. The switch shown is of the three way type, however, and is not provided with such markings. By merely omitting one of the end stationary contacts and its assembled terminal the switch may be made of the true "on and off type and may have position designating means on the handle.

The projection I0 is hollow and open at the rear to provide a chamber 25 to accommodate the switch mechanism. That part of the circumferential wall of the chamber which merges into the shoulder 20 is provided with a plurality of longitudinal grooves 2! cut through the wall for substantially its full height. Radially outwardly of the inner surface of the circumferential wall each groove is widened as at 28 to accommodate that portion 29 of a connector strap extending between the terminal 30 and the stationary triangular contact 3|, all formed integral. The contact 3| projects at right angles to the portion 29 to extend into chamber 25 through groove 21 and the outer portion is widened as at 32. The narrower portion of contact 3| which extends through groove 21 rests on the bottom of this groove for accurate vertical location of the contact for cooperation with the movable contact assembly about to be described. Also the terminal tab 30 or a portion thereof may rest on the surface or back face of the cover plate as seen at 33 in Fig. 3. Spacing here is seen to be obtained by a spigot 34 formed integrally with the part 30 to give additional depth for threading. The terminal 30 is drilled and threaded to accommodate the attachment screw 35 for securing the conductors thereto and the end of the screw is accommodated in extension 36 of slot 27.

For holding the contact and terminal assemblies in position, after they are slid into the accommodating slots and grooves, an insulating back cover plate 31 is supplied, fitting inside of the inner circumferential bead 38 which reinforces the cover plate a short distance radially beyond the circumferential wall of the recess 25. This back cover plate is formed of some tough insulating material such as vulcanized fiber, fits closely within the bead 38, has portions cut out as shown in dotted lines to clear the heads of screws 35, but otherwise rests on a major portion of each of the terminal tabs 30 to hold them in place. The insulating back cover is attached to the main plastic cover by a pair of drive screws 39 passing through openings 39 as viewed in Figs. 2 and 3.

All of the several stationary contacts 3| are in the same plane parallel to the face of the cover and in the three-way switch here shown are three in number. A movable bridging contact assembly is arranged to selectively connect the center and either of the outer stationary contacts, while in a true on and off switch only the central and one outer contact is used, which are either bridged or unbridged by the movable contact assembly. Such an assembly is capable of breaking the circuit at both engaged contacts and comprises a pair of generally U-shaped integral contact springs having arms 40 and all formed of bronze Or the like and held superimposed on each other, as later described, to permit the outer tips 4| of arms 40 to clasp the opposite faces of the stationary contacts with which they are in engagement. Suitable lateral, flaring lips 42 on tips 4| provide for ready sliding over the tapered edges of the stationary contacts in a manner well understood in this art.

The two contact springs are adapted to be held assembled by a contact carrier 43 shown in Fig. 6. It is a stamping of sheet metal having a body and a plurality of tongues or arms, the one indicated by reference character 44 being bent up at right angles to the plane of the body and being bent to roof shape at its outer end and perforated through the ridge at 45 to receive one end of the operating spring. A tab 46 opposite the journal opening 41 in the carrier body from the spring arm 45, provides for accommodating the positive kick-off forks on the handle assembly. to be later described. The substantially radial arms 48 are in the plane of the body and cooperate with parts of the housing to limit the throw of the contact assembly, as will appear later. The short lugs 49 are intended to be bent over, as seen in Fig. 5, to clamp the contact springs to the carrier. These springs are perforated at 50 with an opening co-axial with 4'! and the spacing between the contact arms 40 is such that the arm 44 is received tightly between them, making a very rigid assembly when the tabs are bent down. A snuffer plate 5| of vulcanized fiber or the like, having the same radius about its matching bore as the arms 40, is provided and assembled over the arm 44 as shown in Fig. 4 to snuff out any incipient arcs which may start during the operation of the switch. It is cut away at 52 over the tips of each contact spring and is of slightly less arcuate extent than the larger angle between arms 48.

The contact and snuifer assembly is journalled on the shoulder 54 of a screw passing the holes in the snuifer, spring blades and carrier and positioned centrally in the recess or chamber 25 and received in the thickened bolster portion 55 in the central bottom part of the housing projection. This provides a fiat surface 56 for the body portion of the contact carrier to bear on so that smooth rotation is effected while holding the contact spring tip in the proper plane to pass onto or off the stationary contacts 3|. The throw of the contact assembly so that it will bridge first the middle and one outer contact and then the middle and the other outer contact is limited by means of a stop wedge 51 integral with the switch housing and having the edges 58 and 59 adapted to contact alternately with one of the arms 48 on the contact carrier. In both Figs. 2 and 3 the right hand lug is in engagement with the right hand face 59 of this stop wedge 51. The angle between the other face 58 and the opposite stop leg 48 indicates the total throw of the switch contact assembly.

The stop triangle 51 has an elevated fiat surface 60, considerably higher than the surface on which the contact assembly travels, providing a base for the operating handle assembly which is fulcrumed on pin 8| having a head 62 resting on top of the inner end of handle 22. To prevent the accidental withdrawing of this pinv its head is substantially engaged by the insulating back plate 3?. The handle 22 is a plastic part of the shape seen in Figs. 2, 3 and 4, and is recessed on its inner face to the form shown at 63 to receive the inner end of the spring operator 64 comprising a strip of metal whose inner end is sized to closely fit in recess 63 and perforated to accommodate pin 6|. The outer end of the spring operator is narrowed and offset to give it clearance above the head of the pivot screw for the contact assembly. The outer rounded end is provided with a perforation 65. Between this perforation and that numbered 45 in the contact carrier arm 44 is biased the helical spring '61 having tangential ends 68 each provided with a right angled terminal member 69. One of these terminal members fits beneath the spring operator 64 with only the arm 68 engaging in its opening 65 while the other terminal member passes through the opening 45 in the arm 44 with the arm C 8 bearing against the inner side of the arm 44 in the V groove therein as seen in Fig. 4.

The operation of this type of switch will be clear to those skilled in the art because the compression and mounting of the coil spring is such that it forces the contact carrier to move its full stroke whenever the spring operating arm 64 passes slightly beyond the dead center alignment of the pin 62, the hole 65 in the spring operator and the hole 45 in the arm 44 on the contact removable carrier. This action takes place because the hole 65 is closer to the arm 44 than is its fulcrum 54.

Snap switches of the type described are sometimes inclined to stick, because of tightness of the movable and stationary contacts, because of slight arcing and burningor the like, and it is desired to provide what is termed a positive kickoff for insuring movement of the contact assembly in the event action of the spring is not sufiiciently strong to break the engaged contacts apart. Such action is conveniently provided by the forked end of the plastic operating handle, the furcations 12 on the inner end of this lever, spaced about the width of the main portion of the spring operator, are of just suflicient length to engage the arm 46 of the contact carrier. In Fig. 3 a portion of the spring operator is broken away to expose this arm and indicates the handie at the limit of its movement toward the left from the position shown in Fig. 2 before providing positive kickoff. The spring is about lined up to cause throw of the movable contact assembly and now the left hand furcation 12 is engaging the left edge of arm 46 on the carrier so that further movement of the handle to the left causes this furcation to move to the right and kick the contact assembly counterclockwise. The initial movement of the carrier loosens the contacts and the spring then takes over to complete the snap. On the reverse operation the other furcation performs the same operation.

It will be seen that the above assembly arrangement provides a minimum of parts and securing means and insures a smooth and sure acting switch of minimum depth and entirely outside of the confines of the box on which the cover is applied.

I claim:

1. In a box-cover switch unit of the type described, in combination, a substantially flat cover member of insulating material adapted to be secured over the face of a junction box, a hollow projection on the front face of said cover to house a switch assembly and open through the back of said cover, terminals resting on the back of said cover radially outwardly of the opening and having contacts extending along the walls of the opening and into said projection, a movable con tact assembly pivoted within the hollow of said projection for cooperation with said contacts and a handle-operator assembly pivoted in said projection and extending out through a circumferential wall thereof.

2. The box-cover switch unit as defined in claim 1 in which the movable contact assembly and the handle-operator assembly are pivoted about spaced axes normal to the plane of the cover.

3. In a box-cover switch unit, in combination, a unitary cover and switch housing of insulating material including a disc of a size to act as a box cover and a hollow protuberance on the front of said disc open for access to the chamber therein atthe rear face of the disc; a plurality of wiring terminals mounted on the rear face of said disc along the periphery of said opening, each terminal having a contact extending into the said chamber; a movable contact assembly pivoted centrally of said contacts for cooperation therewith; a handle-operator assembly pivoted eccentrically to said contacts; means operatively associating said assemblies to provide snap operation of the former on movement of the latter; said protuberance having an opening in its peripheral wall through which the handle extends for access at the front of the disc.

4. In a box-cover switch unit, in combination, a molded housing and box-cover of insulating material including a substantially flat cover disc and a centrally disposed switch housing protuberance entirely on the front face of the disc and having a chamber open to the rear of the disc; a switch wholly confined in said chamber and including a movable contact assembly pivoted for oscillation at the bottom of the chamber, a switch operator pivoted in said chamber above the said assembly, means connecting the assembly and operator to effect snap action of the former upon movement of the latter, a handle secured to said operator and extending through an opening in the protuberance side Wall, a plurality of wiring terminals overlying the rear face of the disc at the periphery of said chamber, and a stationary contact connected to each terminal and positioned Within and adjacent the chamber wall for engagement by said assembly.

VICTOR R. DESPARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 482,936 Wright Sept. 20, 1892 945,969 Marshall Jan, 11, 1910 1,339,847 Harvey May 11, 1920 1,593,927 Bissell July 27, 1926 1,738,968 Selah Dec. 10, 1929 1,778,676 Kempton Oct. 14, 1930 2,085,217 Hart June 29, 1937 2,236,344 Meuer Mar. 25, 1941 2,240,196 Solenthaler Apr. 29, 1941 2,269,171 Benander Jan. 6, 1942 2,279,065 Schellenger Apr. 7, 1942 2,314,714 Kouyoumjian Mar. 23, 1943

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