US2416253A - Switch - Google Patents

Description

Feb. 18, 1947. w. c. FURNAS 2,416,253

' SWITCH Filed Nov. 22, 1943 s Sheets-Sheet 1 INVENTOR.

. ATTORNEYS.

' Feb. 18 1947. FURNAS 2,416,253

SWITCH Filed Nov. 22, 1943 3 Sheets-Sheet 2 INVENTOR.

Feb. 18 1947. w. c. FuF'NAs 2,416,253

' Q v SWITCH Filed Nov. 22, 1943 s Sheets-Sheet s 3/ i a: !.3- a0 INVENTORY Patented Feb. 18, 1947 SWITCH William C. Furnas, Batavia,

111., assignor to Furnas Electric Company, Batavia, 111., a corporation of Illinois Application November 22, 1943, Serial No. 511,221

13 Gla-ims. (Cl. 290-424) This invention relates generally to improvements in switches, and relates more specifically to'improvements in the construction and operation of combined manually actuable and automaticaliy operable electric switch assemblages.

The primary object of-the present invention is to provide a: new and useful electric switch assemblage which is simple and compact in construction, and which is also extremely reliable and efficient in use.

Many different types of electric switch mechanisms for diverse purposes, have heretofore been proposed and used extensively, and in some of these prior switch structures provision has been made for automatically interrupting the electric circuits in case of dangerous overloading thereof. Thermal overload devices of various kinds, whereinthe circuit is broken under overload conditions,

' by means of a heating element or coil coacting with a solder pot and ratchet mechanism for releasing the movable contacts for quick opening, have also been previously used; and in some of these prior thermal overload switches, the overload release coacted with the same switch contacts which were normally manually actuable to open and close the circuit. While a number of these prior combined manually manipulable and thermal overload operable switch assemblages were quite satisfactory in use, most of them were unduly complicated unreliable in. operation, and. required: intricate and sensitive mechanisms which were costly to construct, diiiicult to assemble, and which could not be repeatedly operated for long: periods of time and under severe conditions. without requiring replacement of parts resuiting in loss of valuable till e. t is also necessary in. thermal overload sw ches of this class, to. provide means for promptly and safely restoring the. switch to normal by resetting the overload. device after actuation thereof, most of the; prior assemblages lacked simple and conveniently manipulable means for so doing, so that all of the previous thermal overlcad switch assemblies embodied one or more highly objectionable features.

It. is therefore a more specific object of my present invention to provide an improved combined' thermal overload and switch. device wherein all of the above mentioned objectionable features are eliminated, and which is always trip free?" for operation of the thermal overload mechanism.

Another specific object of this invention is to provide. a sturdy electric switch in which the same contacts are operable to control a circuit, both normally and under emergency ccnditions, with the aid of common actuating means, and wherein. the operating member need merely be pushedorstruck in order tointerrupt the circuit.

A further. specific object of the invention is to provide a combined manually actuable electric switch and thermal overload device, wherein the normal actuator for the switch is also utilized to effect prompt resetting of the overload device after operation thereof, and in which normal use of the switch actuator in no way interferes with proper functioning of the device.

Still another specific object of the present invention is to provide an improved overload tripped switch assemblage for electric circuits, which is extremely compact and durable in structure, and all parts of which are normally thoroughly concealed and protected while being readily accessible for inspection.

An additional specific object of my invention is to provide an improved electric switch which is shock resistant and water-proof, and which can be manufactured at moderate cost so as to withstand severe service for a long period of time.

These and other specific objects and advantages of the invention will be apparent from the following detailed description.

A clear conception of the several features constituting my present improvement, and of the construction and operation of a combined manually operable switch and thermal overload device ernbcdyin'g the invention, may be had by referring to the drawings accompanying and forming a part of this specification wherein like reference characters designate the same or similar parts in the various views.

Fig. 1 is a central section through the support ng bracket and enclosing casing and an offcenter scction through the overload device and contact mechanism, of one of the improved switches, showing the overload slide set and the switch contacts in closed position;

Fig. 2 is a similar section through the switch assemblage, showing the overload slide still set and the switch contacts in open position;

Fig. 3 is another similar view of the switch mechanism, showing the overload slide tripped so as to place the switch contacts in open position, while the normal switch actuating elements are in contact closed position;

Fig. 4 is a transverse section through the switch assembly, taken along the line l l of Fig. 1;

Fig. 5 is an inside View of the supporting bracket of the switch assemblage, showing the pivotal mounting for the actuating wedge in section;

Fig. 6 is an enlarged fragmentary transverse section through the latching and release mechanism of the thermal overload device;

Fig. '7 is a similarly enlarged fragmentary longitudinal section through the latching and release mechanism of the thermal overload device; and

Fig. 8 is a simple wiring diagram showing a typical electric circuit adapted to be opened and closed with the aid of the improved switch mechanism.

While the improved features have been shown and described herein as being embodied in a direct current switch assemblage, it is not my desire or intent to thereby unnecessarily restrict the scope or utility of the improvements which are adapted for more general application to alternating current control switches as well.

Referring to the drawings, the present improved electric switch mechanism comprises in general, a rigid mounting or supporting bracket I; a combined overload and switch contact carrier frame Ii detachably secured to the bracket I 0 by means of screws I2; two pairs of fixed contacts I3 rigidly secured to the frame II in laterally spaced relationship; two corresponding movable bridge contacts I4 formed of conducting material and biased toward the adjacent fixed contacts I3 by helical compression springs I5, and being mounted upon reciprocable parallel stems I6 formed of insulating material and slidably coacting with slots in the frame I I; a thermal overload device of the solder pot type also carried by the frame II and having a ratchet release cooperable with a slide I! which is movable along the frame II in a direction parallel to the contact carrier stems, the slide I1 being provided with transverse fingers I8 movable in alinement with the stems I6; a helical compression spring I9 coacting with an end of the slide I! and reacting against a transverse yoke 20 secured to the frame II, this spring constantly tending to urge the slide I'I toward contact opening position; a tapered element or wedge 2I movable into and out of the gap between the fingers I8 and the adjacent ends of the contact carrier stems It, by means of a reciprocable rod 22 and a manipulating knob 23; and a closure cover or housing 24 detachably secured to the bracket I 0 by screws 25.

The mounting or supporting bracket I0 may be formed by casting or otherwise, and is provided with threaded openings 26 adapted for attachment of the electrical conductor conduits, and also has integral attaching flanges 2'7, see Figs. 4 and 5. The main bracket I 0 is furthermore provided with a waterproof seal 28 embracing the rod 22, and with an annular sealing gasket 29 against which the housing 24 may be forced by the screws 25 so as to provide a moisture-proof enclosure for the thermal overload and switch mechanisms, as illustrated in Figs. 1 to 5, inclusive. The closure housing 24 is, however, readily removable so as to reveal the normally concealed mechanism for inspection, and the bracket I0 may obviously be suspended in any desired position.

The normally concealed frame movably attached to the bracket the screws I2, is formed of durable insulating material, and is provided with two separate chambers within which the two sets of fixed and movable switch contacts I3, I4 are confined. As previously indicated, the two movable bridge contacts I4 are constantly urged toward the adjacent stationary contacts I3 by means of helical II which is re- Ill by means of compression springs I5 as depicted in Figs. 1 to 4 inclusive, and these springs I5 surround the inner ends of the movable contact supporting bars I6 and are seated in sockets formed in the central transverse wall 30 of the frame II. The parallel contact supporting bars I6 are formed of bars of suitable insulating material and have their outer ends chamfered and pointed as shown 4 in Fig. 1, for proper cooperation with the slide fingers I 8 and with the wedge 2 I.

The thermal overload device which is also carried by the frame II, is of the type disclosed in Patent No. 2,296,157, granted September 15, 1942, being shown in detail in Figs, 1, 2, 3, 6 and 7, and comprises a ratchet wheel 3i having a solder pot 32 formed integral and concentric therewith; a heating coil 33 surrounding the solder pot 32 and being connected in series with one of the fixed contacts I3; a fixed shaft 34 permanently secured to the center wall 30 of the frame I and having therein annular grooves 35 containing solder slugs with which the pct 32 coacts; a pawl 36 cooper-able with the teeth of the ratchet wheel 3| and being resiliently mounted upon the reciprocable slide l1; and the compression spring I9 which is cooperable with the end of the slide I! as illustrated in said patent, so as to con stantly urge the fingers l8 toward the outer ends of the movable contact carrier bars or stems I3.

The ratchet wheel BI is normally retained within the path of movement of the pawl 36 by a retainer 37, and while the wheel 3i is normally soldered to the fixed shaft 3 1 by means of the solder slugs disposed within the grooves 35, the coil 33 will become heated under overload conditions and will melt the solder and thereby release the ratchet wheel 3I for free rotation about the fixed shaft 34. The pawl 36 is constantly urged toward the ratchet wheel 3| by means of a small spring 38 as shown in Figs. 6 and 7; and the slide I1 is formed of wear resistant material and is guided along the frame II for movement parallel to the switch contact carrying stems It by means of a removable plate 39. The fingers I8 and the transverse yoke 20 against which the tripping spring I 9 reacts, may be formed of metal stampings; and while the pawl 33 normally coacts with the fixed ratchet wheel 3| to compress the spring I9 and hold the fingers I8 out of the normal range of movement of the outer ends of the contact stems I6 as in Figs. 1 and 2, release of the wheel 3I due to overload conditions will cause the spring I3 to trip the slide I1 and will open both of the movable contacts I4 as shown in Fig. 3.

The tapered block or wedge 2| which is movable transversely of the direction of travel of the stems I6 and slide H, by means of the rod 22 and knob 23, may be formed of hard rubber or other suitable wear-resistant material, and has two oppositely inclined wedge surfaces of different lengths. This wedge 2I is disposed within a cavity in the bracket Ill and is normally movable into and out of the gap between the fingers I8 and the outer ends of the movable contact carrier stems I6, by means of the rod 22 and knob 23, as will be noted from Figs. 1 and 2. In order to shield the wedge H from the fixed contact terminal screws 40, an insulating shield 4I may be provided, see Figs. 1 to 4 inclusive. The wedge 2I coacts with helical compression springs 42 confined within recesses in the bracket I0, and is pivotally mounted upon the reduced inner end portion 43 of the actuating shaft 22 as indicated in Fig. 5. The shorter taper of the wedge 2I is normally adapted to coact with the outer chamfered ends of both contact stems I6 when the button or knob 23 is pushed inwardly, so as to simultaneously open both movable contacts I4, as shown in Fig. 2; and when the knob 23 and wedge 2I are pulled outwardly, the springs I5 will simultaneously close both of the movable contacts I4. However, when the wedge 2| is withdrawn and the overload device. becomes. active as in Fig. 3,- then the fingers: l8 are brought into. engagement withtheouter ends of both stems 1 [6, thereby automatically opening both movable contacts M and breaking the circuit: through both sets of-fiXed and: movable contacts l3, l4; and the longer taper of the wedge- 2| may thereafter be utilized toresetitheoverload device:

Theflexible. suspension of the. wedge 2| upon the actuating rod or shaft 22, will permit the wedge toa fioat and properly contact both of the stems lfi and fingers I8iwithout undesirably stress- 'tacts closed position, the rod is provided with an annular groove as as indicated in Figs. 1 and 3. The balls 45 are pressed. towardv the rod 22 by means of springs 47, and are removably confined within a'bored' socket in the bracket ill by a screw 48*. The bracket lb may'also be provided w th one or more index'plates 49 for indicating on and. off movement of the rod 22. and knob 23', and allassembly screws of the mechanism ma be provided withlock washersfor preventing loosening thereof. due to shock or'vibration.

-'l he improved two pole switch and overload protective assemblage maybeapplied to a direct current electric circuit in. the manner shown diagrammatically in Fig; 8', and the conductors leading to and from theswitch mechanism may be extended through moisture-proof conduits connected to the threaded bracket openings 26. After proper installationof the assemblage in an electric circuit, the manually manipulable knob 23- and rod 22 may be utilized to make or break 7 the circuit, without interference by the overload protective device, by merely pushing or pulling on the knob 23. When this knob'has been pulled out as in Fig. l, the springs it are active to close both sets of switch contacts 1% l4 and the overload mechanism is free to function if excessive overloading of the circuit should occur. If the knob 23 androd 22 are pushed inwardly to the position shown in Fig. 2, both sets of switch contacts It, 54 are opened tlius interrupting the circuit in two places and eliminating all possibility of overload. However, when the circuit is closed d-raival of the wedge 2|, and excessive overload conditions are established, then the heating coil 33 melts the solder slugs within the solder pot 32' thereby releasing the ratchet wheel ill for free rotation about'the fixed stub shaft 34, and the pawl 35 and slide H are quickly released and urged toward the extreme left as viewed in Fig. 3, thus causing. the fingers 18 to contact the outer ends of the stems l6 and quickly opening both sets of switch contacts 53, M. This movement of the overload slide I1. is' produced by the. spring 55-; and in order to thereafter reset the overload device, it is only necessary to await solidification oi the solder slugs and to subsequently push the knob 23 and wedge 21 inwardly until the wedge 21 coacting with the fingers iii has shifted the slide I! and the pawl 33 backinto engagement with the teeth of the relocked ratchet wheel 3i. It will thus be noted that the single wedge 2 l serves not only to effect normal actuation of the switch contacts, but is also utilized to reset the overload device, and this wedge in no manner interferes with the automatic functioning of the. overload protective mechanism.

From. the foregoing detailed description it must be apparent that my present invention provides an; lproved' combined electric switch and overloadprotective assemblage which is extremely s mple, compact and durable in construction, and which is moreover highly eiiicient in operation. The-thermal overload device while being free to function automatically and quickly when the switch is closed, can be just as rapidly resetwith the same simple wedge assembly which is normally employed to actuate the switch. The same sets of contacts are also utilized to make and break the oi uit during both manual and automatic operation, and additional protection is afforded by utilizing two sets of contacts which may be simultaneously either opened or closed. The improved wedge structure also performs its various functions in an effective manner without subjecting the various parts to undesirable stresses, and serves to equalize the pressures on both of the contact carrier stems by virtue of its improved construction and mounting. The switch assemblage is moreover shock-resistant, moisture-proof, of sturdy and durable construction, while all elements thereof are conveniently accessi le for inspection and operation. The ll 'oved switch while being quickly and conveniently operable cannot be accidentally placed in contacts closed position by shock or bumping of the assemblage. lfhe new switch mechanism can also be manufactured at moderate cost for use with either direct or alternating current, and has proven highly satisfactory and successful in actual use.

While the i roved switch actuating mechanism has been shown and described herein as being applied to a switch having only two sets of contacts, it is also applicable to switches having more than two sets of contacts and to thermal overload devices having more than one heater, such as shown Furnas Patent No. 2,296,157.

It should be understood that it is not desired to limit this invention to the exact details of construction or to the precise mode of use, herein shown and described, for various modifications within the scope of the appended claims may occur to persons skilled in the art.

I claim:

i. In combination, relatively movable switch c acts for closing and opening an electric circu a slide coacting with said contacts and being operable thermal overloading to separate said contacts and to thereby automatically open the circuit, and a wedge havin oppositely inclined wedge surfaces one of which is normally operable to selectively more said contacts in order to effect both c sing and opening or" said circuit, of said wedge surfaces being cooper 1 said slide to reset the latter af er said automatic opening of the circuit.

2. In combination, relatively movable switch contacts for clos ng and opening an electric circuit, a slid, enacting with said contacts and being e le by thermal overloading to separate said cts and to thereby automatically open the circuit, a wedhaving oppositely inclined wedge su ce one of i 'hlch is normally operable to selectively move contacts in order to effect both closing and opening of said circuit, the other of said wedge irfaces being cooperable with said slide to reset the latter after said automatic opening of the circuit, and manually operable means for reciprocating said wedge to effect both normal opening and closing of the circuit and return of said slide to inactive position.

3. In combination, two sets of fixed and movable contacts for simultaneously making and breaking the same electric circuit, a thermal overload device for automatically separating the contacts of both sets to break the circuit, and a single wedge having opposite Wedge surfaces one of which is normally movable to separate said contacts and the other of which is movable to reset said device after automatic operation thereof.

4. In combination, two sets of fixed and movable contacts for simultaneously making and breaking the same electric circuit, a thermal overload device for automatically separating the contacts of both sets to break the circuit, a single wedge having one wedge surface normally movable to separate said contacts and also having an opposite wedge surface movable to reset said device after automatic operation thereof, and manually actuable means for movin said wedge in like manner during both normal making and breaking of said circuit and during resetting of said device following automatic operation thereof. 5. In combination, two sets of fixed and movable contacts for simultaneously making and breaking the same electric circuit, the movable contacts of said sets havin reciprocal parallel guide stems, a slide movable parallel to said stems and being normally out of engagement with the stems but cooperable therewith to move said movable contacts and to break the circuit under overload conditions, and a wedge movable transversely of the direction of movement of said stems and slide to effect normal movement of said movable contacts and to also reset said slide.

-6. In combination, two sets of fixed and movable contacts for simultaneously making and breaking the same electric circuit, the movable contacts of said sets having reciprocal parallel guide stems, a slide movable parallel to said stems and being normally out of engagement with the stems but cooperable therewith to move said movable contacts and to break the circuit under overload conditions, a Wedge movable transversely of the direction of movement of said stems and slide to efiect normal movement of said movable contacts and to reset said slide, and a single wedge movable across said stems and slide to break said circuit and to also reset said slide after normal conditions have been restored.

7. In combination, two sets of fixed and movable contacts, the movable contacts of said sets having laterally spaced simultaneously movable reciprocable carrier stems, a wedge movable laterally of said stems to simultaneously move the latter in the same direction, and an actuating rod for said wedge upon which the wedge is pivotally mounted the pivotal axis of said rod being disposed transversely of and between said stems.

8. In combination, twosets of fixed and movable contacts, the movable contacts of said sets having laterally spaced simultaneously movable reciprocable carrier stems, a wedge movable laterally of said stems to simultaneously move the latter in the same direction, an actuating rod for said wedge upon which the wedge is pivotally mounted, and an overload protective device cooperable with the circuit controlled by said contacts and havin a tripping slide provided with fingers movable in the planes of reciprocation of said stems, said wedge also being cooperable with said fingers to reset said device.

9. In combination, two sets of fixed and movable contacts, the movable contacts of said sets having laterally spaced parallel and simultaneously reciprocable carrier stems and being spring biased toward closed position, and a pivotally suspendedwedge movable laterally of said stems and being cooperable therewith to simultaneously open said movable contacts the pivotal axis of said wedge being disposed transversely of and between said stems.

10. In combination, two sets of fixed and movable contacts, the movable contacts of said sets having laterally spaced parallel and simultaneously reciprocable carrier stems and being spring biased toward closed position, a pivotally suspended wedge movable laterally of said stems and being cooperable therewith to simultaneously open said movable contacts, and an overload protective device connected in series with said contacts and having a tripping slide provided with fingers movable in the planes of reciprocation of said stems, said wedge also being cooperable with said fingers to simultaneously reset said device and to open said movable contacts.

11. In combination, a'set of fixed and movable contacts, the movable contact of said set having a reciprocable carrier stem, a wedge cooperable with the end of said stem to move said movable contact, and an actuating element for moving said wedge, the wedge being pivotally suspended from said element and the pivotal axis being disposed transversely of said stem.

12. In combination, a set of fixed and movable contacts, the movable contact of said set having a reciprocable carrier stem, a wedge cooperable with the end of said stem to move said movable contact, an actuating element for moving said wedge, the wedge being pivotally suspended from said element, and an overload protective device connected in the same circuit with said contacts and having a tripping member provided with an element movable in'the plane of reciprocation of said stem, said wedge also being cooperable with said element to simultaneously reset said device and to open said movable contact.

13. In combination, a set of fixed and movable contacts, the movable contact of said set having a reciprocable carrier stem, a wedge cooperable with the end of said stem to move said movable contact, an actuating element for moving said wedge, the wedge bein pivotally suspended from said element, and an overload protective device connected in the same circuit with said contacts and having a tripping member provided with an element movable in the plane of reciprocation of said stem, said wedge also bein insertible between said stem and element to simultaneously move said member and said movable contact.

WILLIAM C. FURNAS.

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

UNITED STATES PATENTS Kuhn Jan. 22,

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