US2268943A - Fused switch box - Google Patents

Description

Jan. 6, 1942. E, JQHANSSON 2,268,943

FUSED SWITCH BOX Filed June 11, 1958 2 Shets-Sheet l Jan. 6, 1942. JOHANSSQN 2,268,943

FUSED SWITCH BOX Filed June 11, 1938 -2 Sheets-Sheet 2 Patented Jan. 6, 1942 FUSED SWITCH BOX Ernest G. Johans son, Watertown, Mass., assignor to Anchor Manufacturing Company, Boston, Mass, a corporation of Massachusetts Application June 11,

Claims.

-This invention relates to a fused switch box which 'contains control switches and also fuses for apower circuit such as for a range and anumber of ordinary lighting circuits.

Since a power circuit must be capable of carrying a relatively heavy current, provision must be made for corresponding fuses, such fuses being commonly of the cartridge type. The customary fuses for lighting circuits which carry comparatively small currents are of the plug type.

According to the present invention, an im-- proved switch box is provided containing a mainswit'ch to which is connected a fused switch for apower circuit and a number of receptacles for plug fuses withterminals for lighting circuits.

It is an object of the present invention to prov-ide a main switch of improved design constructed to maintain the switch elements in firm contact for good electrical connection when the switch is closed, theswitch having an operating mechanism by which the movable switch elements are moved slowly from the stationary switch elements when the switch'is being opened,

but snap quickly into con-tact therewith when thes'w'it'c'h is being closed. The current-carrying parts'within the box are so arranged and designed as to minimize resistance-and consequent loss of voltage and power in the conductors within the box which carry heavy currents.

"Another object of the invention is to provide switches capable of carrying heavy currents but relatively compact in structure so as to leave ample room for line and load wiring when mounted in a switch box of ordinary size.

' It is 'afurther object of the invention to providean improved switch for controlling a power circuit, such switch having its movable "elements, together with suitable fuse holders, carried by a cover member which is hinged to the box. Ac-

cording 'to the invention, the elements of this switch, when the switch is closed, are pressed strongly against each other by their characteristic stiff resilience, the thrust of such pressure on the cover member being taken by a portion of the box itself against which the edge of the cover abuts for this purpose.

It is a further object of the invention to provide partition means which divide the interior of the box into a rear compartment and upper and lower front compartments. According to the invention, the partition means include a dead-front member of sheet metal carrying a block of insulating material part of which is in the upper front compartment and part in the 55 1938, Serial No. 2 13,2723

lower compartment. The part in the lower front compartment isprovided with apertures through which the movable switch elements carried by the lower cover are thrust with the stationary -5 switch elementsmounted in the rear compartment. The portion of the insulating member in the upper-compartment is provided with apertures through which test wires may be thrust for contact with conductors connected to the. stationary switch elements so that the fuses in the lower compartment can be tested without opening the fuse switch, that is, without swinging open the cover member which carries the fuses. The dead-front member is designed to prevent access to any charged parts-except the receptacles for the fuse plugs, such receptacles being shielded from manual contact when the fuses are in place. A-cover member which closes the upper front compartment is hinged to the deadfront member so as to be removable with'the dead-front member from the box. This upper front cover i-s provided with an aperture through which an operating handle for the main switch projects so that the 'main switch can be operated 2 from outside of the box when the upper front cover is open or closed. The contacting switch elements 'of the main switch are so arranged as tobevi'sible-for inspection when the dead-front cover isremoved, this member being removable without disturbing the main switch.

For other advantageous features of structure, reference may be had to the description of a switch b'ox embodying the invention which folparts are shown in a different view of operation. V Figure '7 is a fragmentary section view similar to Figure 3"but showing the parts in a different position. v p

Figure 8 isa fragmentary elevation of the box with the covers and dead-front member removed.

As showninFigure i, the box lili'tself may be of conventional size and shape and is preferably made of stamped sheet metal. Suitable knockouts I2 are provided in the side and end walls of the box, and also in the rear wall, for the admission of service and load wires as desired. The box is also provided with a dead-front member l4 which, as shown in Figure 2, is chief ly of stamped sheet metal but which also includes a block I6 of insulating material such as porcelain. The box is provided with two cover members, the upper cover member l8 being hinged to the dead-front member l4, the lower cover 20 being hinged to the box itself. The lower end of the dead-front member I4 is received and held by a pair of brackets 2| mounted on the inside of the lower end wall of the box. These brackets each have a notch 22 so shaped as to form a point 23. The notches 22 are readily entered by the lower end of the member I4 when it is inclined outward, but, when it is swung to its normal position parallel with the rear wall of the box, its lower end portion is gripped by the edges of the notches and the points 23 dig into the rear face of the member I4 so that it has a good electrical connection with the box. The upper end of the dead-front member I4 is secured to the box as by suitable screws 24. The dead-front member I4 is provided with an aperture 25 through which are exposed receptacles for plug fuses and an operating handle for the main switch, as hereinafter described. The upper cover [6 is also provided with an aperture 26 through which the handle for the main switch projects when the upper cover is closed so that the main-switch can be operated from outside of the box when the upper cover is either open or closed.

Each cover member is provided with a handle 21 hinged thereto. These handles may be sheet metal stampings and may carry legends to indicate the members protected by the corresponding covers, thus obviating the need of plates on the box for this purpose. a,

Mounted against the rear wall of the box is a block 36 of insulating material such as porcelain. This block carries the main switch and for this purpose is formed with a pair of channels 32 in its rear face and a central aperture 34 extending therethrough from front to rear. In each of the channels 32 is disposed a U-shapedswitch member '36. This member is preferably of hairpin shape, as indicated in Figures and 6, and is of stifily resilient strip metal. As indicated on the drawings, this member may be made of two or more strips of the same or different metals nested to provide greater strength and stiffness. Each member 36 is formed with a shorter leg 38 which is secured against the bottom of the corresponding channel 32 by a pair of screws 40 and a longer leg 41 which is free to move, the end of this leg projecting beyond the end of the channel so as to be visible for inspection when the deadfront member 14 is removed. The block 30 has an extension 42 on its base on which are mounted stationary switch elements 43. A suitable contact element 44 is preferably mounted at the end of the leg 4| of each switch for contact with the stationary element 43. The normal closed position of each switch is shown in Figure 6, the hairpin member 36 being so formed and arranged as to press the element 44 strongly against the stationary element 43 so as to ensure a good electrical connection. In the embodiment of the invention illustrated, the hairpin members 36 are current-carrying parts of the switch andconsist of heavy strips of suitable conducting material, but it is evident that the resilient and current-carrying functions of the members 36 could be separated by connecting the contacting elements 44 to an auxiliary conductor.

The front face of the block 36 is formed with four hollows 45 arranged in square array, two of these hollows being directly in front of each of the switch members 36. In each of these hollows is seated a fuse holder which, as illustrated, may be a socket 46 for a plug fuse, thesesockets being of conventional construction and being secured in place by the screws 46 which also serve as the central terminals of the respective sockets.

For the operation of the main switch, a tension link 50 is disposed in the central aperture 34 of the block 30. Secured to the rear end of the link 56 is a crosshead 52 which engages the rear faces of the legs 4| of the hairpin members 36. The member 52 is of insulating material such as vulcanized fiber. The link 50 is drawn forward to open the switch, suitable means for such movement of the link being illustrated in Figures 3 and 7. As shown, a handle 54 is mounted on a pivot pin 56 which rides in a notch 51 in the front of the block 30, this handle being pivotally connected to the forward end of the link 50 as at 58. The handle 54 thus acts as a lever rockable about the fulcrum 56 to move the pivot point 58 from the position shown in Figure '7 to the position shown in Figure 3. This toggle connection between the handle 54 and the link 56 results in a considerable mechanical advantage which enables the operator to move the contact elements 44 away from the stationary elements 43 against the strong restoring force of the spring hairpin members 36. It is evident that-the line of tensional force exerted on the link 50 is through the pivot 56 and the crosshead 52.

The pivot 58 is so arranged as to cross this line of force, so that when the handle 54 is in the position shown in Figure 3 the force of the springs 36 tends to retain it in this position. If, however, the handle 54 is rocked upwardly a small amount sufiicient to move the pivot 58 above the line of force through the pivot 56, the strong restoring force of the springs 36 snaps the switch elements quickly and powerfully to closed switch position. The mechanical advantage resulting from the toggle connection between the handle 54 and the link 50 also results in a slow movement of the contact elements 44 away from the stationary elements 43 when the switch is being opened. This slow separating movementis desirable and advantageous when the switch is employed in an alternating circuit since such slow separating movement tends to minimize arcing at the break.

The handle 54 may be made in any desired form or of any suitable materials. As shown, it consists of three plates of insulating material such as fiber cut to shape and secured together by suitable rivets or fasteners 60. The outer two of these plates are mounted on the pivot pin 56, the middle plate being cut away as at 62 to receive the link 56 which is preferably of sheet metal. This results in an eificient but economical switch-operating structure. The handlemay be provided with a suitable knob 64 readily engageable by the fingers of the operator as it projects through the opening 26 in the upper cover 18.

The square array of the hollows 45 with the narrow switch handle 54 between makes possible the use of a relatively small and compact block 30 which is only slightly wider than; the aper-' a acaeas 3 ture 25. in. the dead-:frontmember;leaving ample space for wiring on both: sideslof the. block as wellaswithinthe .ends of the box. The :block 38 and switchesymounted thereon can be :used as an independent unit or can be associated with the other apparatuses. shown on'the drawings. Mounted on the extension 42 oftheblocktl) are suitable terminals 88.. which. are adapted to. clamp tightly-the. ends of the service-wires, in the box and which are connected torespectiveswitch elements 43 by short heavy conductors 68. This arrangement is, not only. economical but isv-comparatively efficient .in that long conductors between the switch elements, andthe service wires are-avoided. In addition toitheterminals 6.8 for. the Switch elements, a third terminal is provided for aineutral bus member 18 which extends along the rear wall of the boX behind the bloickiqand, is provided with suitable tenninals 2 ool'lnettible with, var ous r n h ircu t 7 Below theblock asmallerblock M of insulating material-is secured, to the rear wall of the box, Mounted on this block are stationary range switchelements 88 which may be. made of stifily resilient metal strips bent to shape. These elements 88 are connectedas by screws 82 to corresponding conductors 84. As indicated in Figures Sand 6, these conductors 84 may be clamped tightly against the stationary legs .38 of respective. switch members 86 by means of; screws 48 so as to ensure good electrical connections between the main switch members 36 and the range switch elements 88 connected thereto. As indicated in Figure 8, the other two switch elements 88 areprovided with terminal clamps86 adaptedto receivethe ends of load wires for the power circuits. Cooperating with the stationary switch elements 88 area correspondingnumber of movable range switch elements 8], these elements also being preferably made of stillly resilient strip metal pieces bent to shape. The elements 81 are secured to a pair of blocks 88 of insulating material, such as porcelain, which in turn are mounted on the inner face of the lower .cover member 28. This cover member may be made, as indicated in Figure 3, of two plates 89 and 98 secured together face to faceby screws 9|. The blocks 88 are secured to the inner plate 89 by screws 92. The inner plate is hinged directly to the box and carries the cover plate 98, the latter having flanges 88 for the cover 28. Secured to each element 81 is a fuse-holding clip 94 having a pair of spring jaws adapted to receive a tocbe .parallelto theabuttingkportionsof the elementsclll'when'zthe switch .isclosed asaindicated in Figure 3 The .open switch position :of the cover f28rand' parts carried thereby is. illustrated indotted lines in ,Figurev3z As shown, Jthe'contact. elements. 8-1 are. disposed at a slightly. greater distance from the axis of the 4 cover :hin'ge .1 than are the stationary. elements .882. Hence, as'the elements '81. move .into Iclosed switch position,- it

.is necessary 'for them to-push the elements 88 awayfrom the hinge'axis and at the same'time to yield correspondinglytoward the hinge axis.

so that the contacting elements mayassume the positions shown in Figure 3. Hence theends 96 81 are mounted. The major component of this; thrust .will be in the plane of the cover28- As the combined thrust of; the four elements 81 is;

considerable, the box has been constructedso as ;to relieve the hinges of the cover member from this thrust. 'To this end, a front wall portion 98 cartridge fuse 95 in the usual manner. In the particular box illustrated on the drawings, provision is made for holding two cartridge fuses 85, these fuses thus connecting the inner switch elements 88 with the outer switch elements 88, as they appear in Figure 8, when the fuse switches are closed by the engagement of the ele-, ments 8,! with the corresponding elements 88. As the cover 28 is attached to the box itself, the fuse-supporting blocks 88 cannot be mislaid or dropped and broken as is the case where the blocks are completely detached from the box when the fused switch is open. Since the cover 28 is hinged to the box, it is evident that the movable switch elements 81 will describe arcuate paths about the axis of the hinge when the cover 28 is swung open or shut. The portions of the elements 81 which directly engage the elements 88 are therefore arranged so as to be substantially tangent to their arcs of swing about the axis of the cover hinge. The contacting portions of the stationary elements 88 are also arranged so as is providedthis portion having an edge-98 which is abutted by the loweredge of theplate'90 which is-a part of thecover 28. These abutting edges take the thrust of; the switch elements 8-Tirom the hinges so that the cover member 20 swing freelyon itshinges.

' The dead-front member 14 is providedwith a pairof transverse partition elements I88 and I1 2 between which the flanges of the upperand lowergcovers. may enter when the covers are closed: These elements also cooperate with the block 1-6 to form upper and lower front come partments. The switch and fuse elements carried by the cover member 28 are thus disposed in the lower front compartment when the lower cover is closed. The block I8 is provided with apertures I84, as indicated in Figure 2, through which the elements 8'l.p-roject when the fused switch is closed. The stationary switch elements 88 are arranged in the rear compartment in alinement with respective apertures I84 so as to be in position to be operatively engaged by the movable elements 81 when the latter project through the apertures. The apertures I84 are narrow so that the charged elements 88 are protected from contact by the fingers of the operator when the dead-front member [4 is in place. The blocks "5 and 14 together constitute a barrier between the fused switch in the lower portion of the box and the main switch in the upper middle portion of the box.

' tively with the ends of the fuses 95, and are normally concealed and protected by the upper cover member IS. The Inner pair of notches H8 are alined with the conductors 84 shown in Figure 8. Since the outer pair of notches 8. must be near to the inner notches so as to avoid being too close to the edges of the aperture 25, the

outer elements 80 are provided with conductors H2 portions of which are forwardly offset from the conductors 84 and project toward each other so as to be engageable by test wires thrust through the outer pair of the notches I I0. Thus, by means of an ordinary test lamp, either fuse maybe easily tested without opening the cover 20 or the fused switches carried thereby,

It is evident that various modifications and changes may be made in the embodiments of the invention herein shown and described without departing from the spirit or scope of the invention as defined in the following claims.

I claim:

1. In an electric switch, a block of insulating material having a central aperture therethrough and a pair of channels in the rear face thereof, a pair of hairpin-shaped spring metal members mounted in said channels with the front arms of said members bearing against said block, a pair of contact elements mounted on said block behind the rear arms of said sping members and normally engaged thereby, and means for separating said rear arms from said contact elements against the force of said spring, said means including a crosshead engaging said rear ams, a link extending through said aperture and connected to said crosshead, and a toggle element connected to said link.

2. In an electric switch, a block of insulating materialy having hollows in its front face and a pair of channels in its rear face, U-shaped switch elements of spring metal seated in said channels, sockets for plug fuses seated in said hollows, each said socket having a metallic contact element secured to one of said switch elements whereby said sockets and switch elements are held in place and electrically connected, stationary switch elements mounted on said block and normally in contact with said U-shaped switch elements, and operating means mounted on said block and actuable to distort said U-shaped switch elements so as to separate them from said stationary switch elements.

3. In an electric switch, a block of insulating material having a pair of channels in its rear face, a pair of U-shaped members of spring metal seated in said channels, each said member having a shorter leg secured to said block and a longer leg projecting beyond the end of its channel so as to be visible from the front of the block, a switch element mounted on said block behind the visible portion of each said member and normally in contact therewith, and operating means for moving the visible portions of said members away from the contacting switch elements to open the switch against the resilient force of said members, said operating means including a tension element extending through said block from front to rear and a handle connected to said tension element.

4. In an electric switch, a member comprising a pair of nested U-shaped metal strips, the inner strip being of spring metal, a pair of fixed conductors, means securing said member to one of said conductors with one arm of the outer metal strip in direct contact with said one conductor, said other conductor being normally engaged directly by the other arm of said outer strip, and means for forcing said other arm of the outer strip away from said other conductor against the restoring force of the inner strip.

5. In a heavy-duty electric switch, a block of insulating material having a pair of parallel channels in the rear face thereof, a central aperture through the block between said channels, conductors and switch elements mounted in said channels, switch-operating means extending through said aperture, and holders for fuses overload disconnect means on the front face of said block directly in front of said channelsv and electrically connected with said conductors.

ERNEST G. JOHANSSON.

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