US2202535A - Wall box switch - Google Patents

Description

May 28, 1940. F. PEDATELLA WALL BOX SWITCH Filed March 25, 1937 ELECTRIC SUFTQY Patented May 28, 1940 PATENT ogFPlca WALL BOX SWI'IGH Frank Pedatella, New Xeon, Pa.

Application March 25, 1937, Serial No. l325? 4 Claims.

My invention relates to the electrical wiring systems of homes and other buildings, and consists in a particularly eiective organization of' circuit-controlling and circuit-protecting means in a unitary structure.

The object of the invention is to eliminate the necessity of circuit-protecting fuses in such systems.

A further object is to provide with each of the circuit-controlling switches of such systems means for protecting the individual load circuits, so that a failure in one or another of the several load circuits will not interfere with normal operation of the others. In other words, I aim to provide a combined circuit-controlling and ci'rcuit-protecting unit for each room of a building, say each room oi a "nome, whereby a defect in the electric circuit of one room will not im- .pair normal service of the circuits of the other rooms.

I am aware that others have hitherto proposed means for automatically opening a switch uponv 'the occurrence of a short-circuit or other overload in the controlled circuit, and I know that lock-out relays have been used to prevent damage in case the automatically opened circuit be manually reclosed while the overload still prevails. (Note Letters Patent, No. 2,080,502, granted to me May 18, 1937.) However, to these known ends no one has provided structure which may be arranged in compact, unit assembly within a small switch-box, oi the sort now commonly installed within the walls of dwellings, nor has` anyone provided an automatic lcircuit-breaker and lock-out relay assembly which is serviceable with a snap-action switch mechanism of the type which the laws of the various localities speciiy for use in the home. More specifically, my invention consists in particularly eiective organization of circuit-protecting means with a snap-action switch. My structure is compact; the several instrumentalities of the organization are of simplified and economical construction, and are assembled within the relatively small ccnnes of an outlet-box, in such manner asito meet the usual municipal construction codes.

. In the accompanying drawing Fig. I is a sectional view of an outlet-box, showingthe internal organization of the invention in front elevation; Fig. Il.' is a view in cross-section of the box, showing certain parts of the assembly partly in side elevation and partly in vertical section. The broken plane of section of Fig. I is indicated by the lines I-I in Fig. II, and the plane of section of Fig. II is indicated at II-II in Fig. I.

(Cil. Elin-294i Fig. 1U is a View in side` elevation of the relay device embodied in the structure. And Fig. IV is a wiring diagram.

Referring to the drawing, the reference numeral i is applied to a box, a so-called outlet-box, or switch-box, of the sort commonly in use at the present time for housing switches or other electrical devices within the walls of buildings. The box i is made of sheet metal, and in accordance with known practice its side-walls are provided with knock-out openings (not shown) for the introduction of circuit wires a and b. In usual manner the terminals oi exible metal conduits 2 for the circuit wires are secured to the side walls of the box, and it will be understood 'that in service the box l and conduits 2 are embodied within the walls (not shown) of the building. Over the mouth oi the installed box, the usual 'cover plate 3 is secured.

Within the box i, i mount asnap-action switch mechanism. Such mechanisms are known to the art, and the particular type I use need not be considered in detail herein. Suilice. it to say that the mechanism is arranged withinl a housing 4 of hard rubber or other insulating material. and comprises snap-action means, which are responsive to the movement of an arm 9 between its full-line and dotted line positions in Fig.'II, electrically to open and close circuit wire b. The housed switch mechanism 4 is secured in the box, by means of an L-shaped bracket 5.

A switch-operating lever or trigger l is pivotally mounted on a bridge member 6, secured across the mouth of the box I, as shown in Fig. il. The trigger includes a portion that extends into the box and is articulated to the end of switch arm 9, by means of a link 8, and a portion that extends through a slot l0 in the cover-plate 3, whereby in known way the trigger may be snapped between on and o positions, and the switch mechanism shifted between circuitclosing and circuit-interrupting positions. This articulation or iiexible connection of the trigger 'i to the arm 9 of the switch mechanism is an important feature of my construction.

Between the housed switch mechanism C and the trigger i, 'i organize in compact assembly within the box l an electromagnetic plunger il.

The plunger il is provided with a slot Ml through which the switch-operating arm 8 exv tends, and, when the trigger 'i is snapped be tween on" or oir positions and in consequence the arm 9 swings, the plungerI ii slides to or fro in the sleeve I3 and. coil I2. In Fig. JI the trigger 'I and switch arm 9 are shown in the positions in which they rest when a nominal electrical load is closed across the circuit a, b, and, as will presently appear in greater detail, the actuating coil I2 is effective, when a short-circuit or other overload occurs in the circuit, to draw the plunger II downward, with the consequence and eiect that the switch arm 9 is instantaneously swung clockwise, shifting the switch mechanism into circuit-interrupting position, and simultaneously swinging the trigger 1 into olf position. Thus, the 'circuit a, b is automatically opened when an overload occurs.

In compact assembly with the above-described automatic switch mechanism, I organize in the box I a relay device I5 and an electric glow lamp I6, to safeguard the circuit in case the trigger 'I be inadvertently thrown into on position and the automatically interrupted circuit a, b, reclosed While the overload conditions still prevail. The relay device consists of a base I1 of insulating material, which is secured to the inner, vertical Wall of the box I. A high-resistance electromagnet or actuating coil I8 is mounted on base I1, andacross the usual core of the electromagnet or coil an armature I9 extends. The armature is pivotally supported at the upper end of a standard upstanding from the base I'I; the distal end of the armature lies between two contacts 2| and 22 that are mounted in electric isolation from one another on the said base Il; and a tension spring I9a is organized with the proximal end of the armature, such spring tending to maintain the distal end of the armature in engagement with contact 2|, as shown in Fig. III. It will be understood that in this position of the parts the armature I9 stands in circuit-closing position `in the circuit a, b. In the event that the circuit a, b is overloaded, the low-resistance electromagnet or coil I2 attracts the armature II and opens the switch mechanism 4, before the high-resistance electromagnet or coil I8 is adequately energized to swing the relay armature I8 away from contact 2I. If, then, the automaticallyI opened switch mechanism 4 is manually reclosed, the high-resistance electromagnet I8 operates to draw the armature I 9, against the tension of spring Isa, away from contact 2I, and into engagement with contact 22, thereby opening the load circuit a, b and closing lan auxiliary circuit through the glow lamp I8. The lamp I6 is thus energized and provides a visual indication that an overload prevails in the load circuit. The electromagnet I8 is effective to hold the armature in its emergency, circuitguarding position, so long as the switch mechanism remains closed in the overloaded circuit. It will be understood, of course, that the coverplate 3. includes a window (not shown) through which the warning light of the lamp I8 may-be seen.

The tension of spring I 9a may be regulated by adjusting the position of screw I 9b in the proximal end of the armature, and, by so regulating the tension of the spring, the armature may be made delicately sensitive in its operation to currents of predetermined magnitude.

'I'he electrical hook-up of the several elements of my unit is illustrated in Fig. IV. It will be aaoasae observed that the normal load of the circuit a, b comprises in exemplary way a plurality of lamps 23. -The low-resistance electro-magnet or actuating coil I2 that is adapted automatically to open the switch mechanism 4 is connected in the 5 circuit wire b in series with the terminals c, d

of such switch mechanism. The armature I9 of the relay device I5, in its normal position, engages the contact 2| and stands in series with the actuating coil I2 and switch contacts c, d. 10 Accordingly, subject to the manual operation of the snap-action switch mechanism 4, the energizing circuit a, b o1' the lamps 23 may be normally opened and closed. And it will be understood that the operating current for the nor- 15 mal load (lamps 23) is inadequate to energize the low-resistance coil I2 to such degree that the switch-operating plunger II is disturbed. When, however, a short circuit S or other overload occurs in the Vclosed circuit a, b, the abl0 normal current flowing in the circuit energizes the coil I2 far in excess of its normal value, with the result that the plunger II is immediately shifted and the switch mechanism simultaneously shifted into circuit-interrupting position. When the switch mechanism 4 is thus operated automatically to open the overloaded circuit, the armature I9 of the relay I5 remains in engagement with contact 2l.

If the switch mechanism 4 is manually'reclosed, while the overload S still exists, the highresistance coil I8 of the relay device is energized and swings armature I9 into engagement with contact 22, thereby opening the normal circuit through the coil I2 and switch contacts c, d, 85

and closing an auxiliary circuit 24 through the warning light I6. Considering the organization of the relay device more speciiically, it will be noted that one terminal of the high-resistance electromagnet or coil I8 of the relay device is by a lead 25 connected to the circuit wire b at a point between the source of electric supply and the relay contact 2|, while the other terminal of such electromagnet is by a lead 26 connected to circuit line b at a point between the switch mechanism 4 and the actuating coil I2; that is, the coil I8 of the relay is connected in shunt across the actuating coil I2 of switch 4 and the contact member or armature I9 of the relay. When the circuit a, b is operating under normal conditions, the current leaking through the high resistance electromagnet I8 is substantially nil, and the power of attraction of such magnet upon the armature I9 is insignificant. When the circuit is overloaded, however, and the automatically opened switch mechanism 4 is inadvertently reclosed, a circuit b, 25, I8, 28, c, d, S, a is closed, and the abnormally high current flowing therein, because of the short circuit or overload, eiectively energizes the electromagnet I8, whereupon the armature I9 is instantly attracted into its safety position, immediately closing the circuit a, b through the warning lamp I6. And as already mentioned the electromagnet Il remains energized and the armature I 9 is held in its safety or emergency position so long as the switch mechanism 4 is closed in the overloaded circuit. Thus, it will be perceived that my structure is fool-proof; it provides all the protection that the usual fuses aiord, and in addition presents many practical advantages which will be at once apparent to those skilled in the art.

I claim as my invention: 1. In a unit switch structure including a snapaction switch mechanism for controlling an electrical load circuit, a manually operable trigger an auxiliary circuit-protecting device including arranged in conventional organization with said an actuating coil; the improvement herein deswitch mechanism and movable between on scribed in which the actuating coil of said auxiland o positions for throwing said mechanism iary circuit-protecting device is connected in between circuit-closing and circuit-interrupting shunt across the actuating coil of the device rst 5 positions, a circuit-protecting device, including mentioned, whereby, when an overload prevails an actuating coil, adapted upon an electrical in said circuit, with the switch mechanism in overload in said circuit to throw said switch closed position, the voltage drop across the acmechanism from circuit-closing to circuit-intertuating coil of the rst circuit-protecting device rupting position, while simultaneously shifting produces an eilective energizing of the actuating 10 said trigger from on to oiP position; the coil of the auxiliary circuit-protecting device. improvement herein described that consists in 3. The structure of claim 2, in which said an auxiliary circuit-protecting device including auxiliary circuit-protecting device includes an an actuating coil electrically connected in shunt armature, said armature being connected with across the actuating coil of the device rst menthe actuating coil of the rst-mentioned circuit- 15 tioned, with the effect that, when said trigger is protecting device between the terminals of said thrown into on position while an overload exshunt connection of the coil of the auxiliary cirists, the actuating coil of said auxiliary device cuit-protecting device. is eectively energized to produce a circuit-pro- 4. The structure of claim 2, in which said tecting operation of such auxiliary device. auxiliary circuit-protecting device includes an 20 2. In a unit switch structure including a armature, said armature being connected with switch mechanism adapted to control an electhe `actuating coil of the mst-mentioned circuittrical load circuit, manually operable means for protecting device between the terminals o1' said shifting said switch mechanism between circuitshunt connection of the coil of the auxiliary closing'and circuit-interrupting positions, a circircuit-protecting device, and a normally open 25 cuit-protecting device,'inc1uding an actuating signal circuit arranged to be connected across coil connected in service to said circuit, effective said load circuit and subject to said amature. upon an overload in said circuit to move said mechanism into circuit-interrupting position, and FRANK PEDA'IELLA.

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