US1312777A - burnham - Google Patents

Description

G. A. BURNHAM.

ELECTRIC SWITCH.

APPLICATION FILED MAR. 24. 1915;

1,812,777. Patented 411 12, 1919.

2 SHEETS-SHEET 1.

G. A. BURNHAM.

ELECTRIC SWITCH.

APPLICATION FILED MAR. 24. 19w.

1,812,777. Patented Aug. 12,1919.

' 2SHEETSSHEET 2.

Jr?? .J.

,Zivverz 207*;

k f imm GEORGE A. BURNHAM, 0F

SAI TGUS, MASSACHUSETTS, ASSIGNOR T0 S, B. CONDIT, J'B.,

OF BRQOKLINE, MASSACHUSETTS.

ELECTRIC SWITCH.

Specification of Letters Patent.

Application filed March 24, 1915. Serial No. 16,773.

To all whom it may concern:

Be it known that I, GEoReE A. BURNHAM, a citizen ofthe United States, residing at Saugus, in the county of Essex and State of Massachusetts, have invented an Improvement in Electric Switches, of which the following is a specification.

This invention relates to electric-switches and although especially designed for use as a starting-switch formotors, yet many of the novel features may be employed in switches for other purposes, either double 0 single throw.

One of the objects of the invention is the construction of the movable switch-members, whereby they may be composed of resilient flat strips of metal having permanent bends of the desired form and adapted to be flexed through a wide range without breaking, for engagement with the starting and running-contacts, which contacts are widely spaced apart.

Another object is the provision of operating-means for the resilient switch-members, which operate to flex them to cause their engaging portions to engage the fixed contacts upon an initial movement thereof, and to reversely flex them to cause their engaging-portions to rock and slide on the fixed contacts upon a final movement thereof.

Another object is the construction of the switch-contacts, whereby they may be cheaply manufactured and easily applied, and when desired may be detachably secured, and also may be reversible.

Another object is the arrangement of switch-contacts on the extremities of resili ent switch-members, whereby they maybe rocked and slid on the fixed contacts, and engaging-surfaces of a gradually increasing area produced during the rocking movement. Another object is the construction of the operating-means for the movable switchmembers, having associated with it a spring which is compressed when operated to move said members into engagement with the starting-contacts, to store up energy which will be expended to assist in quickly moving said members to disengage said contacts when said operating-means is operated to move said members into engagement with the running-contacts, although said spring has other functions, as will be described.

Another object is the construction of an improved form of gravity latch for the handle of the operating-means, which is arranged to lock said handle in its neutral position, and to prevent it from being moved into running position, but to permit it to be moved into starting position, and which will subsequently permit it to be moved from starting to running position, providing such movement is quickly performed. Otherwise it will engage and lock it Another object is the provision of a closed or isolated compartment for the fuse-connections; and in view of the fact that the operating-means for the switch-member extends through a hole in the plate carrying the fuse-connections, another object is the provision of means for maintaining said hole closedin all positions of the switch operating-means.

Figure 1, is a front elevation of an electrio-switch embodying this invention.

Fig. 2, is a longitudinal vertical section.

Fig. 3, is a plan View, the cover being removed.

Figs. 4 and 5, are transverse vertical sections taken, respectively, on the dotted lines 44 and 55 Fig. 2.

Fig. 6, is a fragmentary detail showing a pair of fixed switch-members, a movable switch-member arranged for engagement therewith, and a portion of the operatingmeans.

Fig. 7 is a detail of the'operating-handle and gravity latch associated therewith.

The box-like structure containing the switch-elements, ashere shown, consists of a compartment 12, and cover 13 therefor, and an oil-containing receptacle 10. The oilreceptacle 10 has an open top, and an inside rabbet arranged around its upper edge. The compartment has an open top, and its bottom wall consists of a heavy plate 14, of insulating material,'such as slate, to which the side wall is secured, and said plate is made substantially co-extensive with the top opening of the oil receptacle to fit the rabbet, thereby tightly closing the top of said receptacle; and securing means are further rovided for holding said receptacle in Xed relation with respect to the compartment, which, as here shown, consists of eye-bolts 15, connected with the receptacle and extended up through slotted ears 16, on the side wall of the compartment. These bolts admit of the removal of the receptacle from the compartment. The cover 13 is arranged Patented Aug. 12, 1919.

' side-wall of the compartment 12.

As a double-throw is here shown, suitable for use as a motor-starting swltch, fuseconnections, such as clips, are arranged on the upper side of the carrying-plate to rethe fixed switch-members.

ceive the fuses, which are readil accessibleupon removal of the cover. These clips consist of strips 20, of resilient metal, bent permanently to receive the cylindrical endportions of fuses of ordinary construction, and have flat seats 21 formed with dovetail recesses. The flat crowns rest on top of the plate and the dovetail recesses receive blocks 22, and screws 23 extend up through the plate which pass through the crowns and enter threaded holes in the blocks, thereby to rigidly secure the clips. These screws also serve as a means for holding As here shown, the fixed switch-members consist of angularly formed strips of metal 25, their upper ends being perforated to receive the screws, and the lower ends carrying the switchcontacts 26. One of the strips 25, is made much longer than the other, and its lower end-portion extends forward a greater distance, so that the lower ends of both strips terminate in approximately the same vertical plane, thus supporting the switch-contacts 26, in substantially the same vertical plane and widely spaced apart.

' The switch-contacts each consist of a block, having a rounded end-portion and large fiat engaging-surfaces 27, upon its upper and under sides, in continuation thereof, and a shank 28 extended from one end of theblock, preferably substantially midway its thickness, with an abrupt shoulder 29, formed at the junction of the block and shank. The shank is adapted to be placed against the lower end-portion of a strip 25, and to be secured thereto by screws or bolts. This construction of switch-contacts admits of its being reversed, thereby admitting of either of its fiat engagingsurfaces being arranged to be engaged by a movable switch-member. Switch-contacts of this description may be employed on all of the switch-members, and in fact may be used generally.

Beneath the'crown or seat of one of the clips a conducting-plate 30, is arranged, which'extends laterally therefrom and has a binding-screw 31 above the plate for the connection therewith of a circuit-wire.

The movable switch-member consists of a resilient strip 35 of sheet metal, one endportion 36, of which is reflexed to form a loop, and the other end-portion of which carries a switch-contact, and said strip is given a permanent bend to enable its looplike end-portion to be secured to the underside of the carrying-plate, and its contactforce and stiffen the attaching end-portion of the strip, so that the strip may be flexed by a force exerted upon it, but will readily return to normal, and the strip may be given a considerable movement without breaking at itspoint of attachment with the carrying-plate. The switch-contact borne by said strip is or may be made the same as the switch -contacts 26, it having a rounded nose 40 and flat engaging-surfaces =11, 41 at its opposite sides, both in continuation of the rounded nose, and a shank 4:2.

The switch, here shown, has a plurality of movable switch-members, arranged for engagement with a plurality of pairs of fixed switch-contacts 26, and the movable switclrmemb'ers are connected together at points intermediate their length and in front of their bends, by a clamp comprising two strips of wood 45, arranged above and below them, which strips are connected together by bolts. The clamp has secured to its upper edge a plate 47, having an ear 48, with a perforation arranged to receive the hooked end of a rod 49, which extends upwardly through a hole 65, in the carrying-plate, and vertical movement of said rod is employed to move the clamp and flex all of the strips 35, thereby to move the switch-contacts borne by them into engage ment with one or the other switch-contact 26, and to cause them to rock and slide thereon.

The rod 19, is a component part of the operating-means for the switch, and, ias here shown, its upper end has an eye 50, which receives the crank-portion 51, of a shaft 52, arranged horizontally in the top part of the compartment, and having bearings at its ends in the side-walls thereof. A rocking movement of the shaft operates to move the rod 49 vertically.

A rocking movement of the shaft moves said rod downward and upward, and in the upward movement said rocking movement is continuous until the upper end of the rod passes the center of the crank-shaft, whereupon the switch-members become locked in closed osition. Movement of the rod in either irection is sufficient first to flex the resilient arm in one direction to move its engagingrtion into engagement with the correspon ing stationary switch-member, and then to reversely flex said arm, whereupon the engaging portion is caused to rock and slide along on the stationary switchmember, and herein such movements o the rod, when arranged for the accomplishment of these functions in sequence, are referred to as the initial and final movements.

A spring 53 is arranged on the rod 49, between the eye 50 and the carrying-plate, which is normally inert, but which is comprgssed upon a downward movement of the ro The lower end of said spring rests on a cover-plate 66, for the hole 65, and the rod extends through a hole in said cover-plate, and the spring acts to hold said plate in engagement with the carrying-plate. As the rod is moved by the crank-shaft'in avertical direction, it is also moved to and fro a short distance in the hole 65, and consequently said cover-plate will be slid along on the carrying-plate and also on .the rod, but in all positions it may occupy, it still entirely covers the hole, so that the chamber containing the switch-elements is entirely separated from the compartment in which the operating-means is arranged, and in which the fuses also may be arranged. To more fully isolate the fuses from the oilwell a partition-wall 70, may be arranged in the compartment 12, which, as here shown, is connected with the cover and said partition-wall is located between the fuse supports and the operating-means.

One end of the crank-shaft projects through the side-wall of the compartment, and a crank-arm or handle 55 is secured to its projecting end by which to rock the shaft, and limiting stops 56, 57, are arranged in the path of movement of said handle to limit its movement when the switch-elements have been moved, respectively, into starting and running position. The handle has extended inward from it a. lug 60, which is en gaged by a gravity-latch 61. Said latch consists of a plate having a semi-circularly formed lower edge for engagement with the lug 60, and has a shallow notch intermediate its length to receive said lug and hold the handle in neutral position. Said plate is pivoted at one side of the shaft-bearing, between said bearing and the stop which limits movement of the handle in running position, hence is eccentric to theshaft.

The shallow notch in said plate holds the lug against movement in one direction, and permits movement in the other direction, as for instance, the lug will be held to prevent movement of the handle in a direction to move the switch elements into running position, but will permit movement of the switch-elements into startingposition. When the handle is moved in the direction to start, the lug disengages the notch and slides along the lower edge of the latch, gradually lifting it. When the handle is moved from starting to running position, by a quick movement, the lug slides along the lower edge of the latch and passes by the notch, but in case such movement is slow, then the lug will enter the notch and movement of the handle will be checked. During movement of the lug from starting to running posit-ion the latch falls by gravity, and such movement being relatively slow enables the quickly moving lug to pass the notch. It will be observed that by the structure and relative arrangementof the parts, the handle must be raised into starting position and also into running position, and if it should fall, for any reason, it will immediately resume its normal position, and become locked. Furthermore, the latch here shown has an easy movement through a short arc, and is not arranged to be thrust suddenly out of engagingposition as most forms of latches heretofore employed. It rests by gravity on the pin at all times, and has a short moderate movement.

The spring necessitates the operator holding the crank positively in starting position, and also assists in a quick return movement, particularly at the start, thereby insuring a quick break of the circuit.

I claim 7 1. In an electric switch, a stationary and a movable switch-member, contact-members detachably carried thereby, said switch-members having contact-member receiving portions arranged to interchangeably receive said contact members, said contact-members being identical in construction and interchangeably attachable to each of said switch-members, and each contactmember carried by either switch-member arranged to properly coiiperate with the other contact-member for the control of an electric circuit.

2. In an electric switch, a movable switch member comprising a resilient strip supported at one end, and a detachable contact carried by the other end of'said strip, said strip having a permanent bend near its supported end and flexing means intermediate its length, said strip being so actuated by the flexing means that the contact carried by the end thereof is moved into contact with a stationary switch member and rocked and caused to slide on the stationary member to a final contact 'engaging position, and said detachable contact having a cylindrically formed end-portion adapted to rock and slide upon the stationary member for initial engagement therewith.

3. An oil switch including an insulating carrying plate, astationary switch member secured thereto and de ending therefrom, a detachable contact blocfi carried by said stationary switch member, a second stationary switch member secured to and depending from said carrying plate, a detachable con tact block carried by said latter "switch member and disposed beneath the contact block carried by the first named switch member, a movable switch member secured to and depending from said carrying plate, said movable member comprisinga resilient strip secured at one end to the carrying plate, a detachable contact block carried by said strip disposed between the contact blocks carried by said stationary switch members, and operating means or said movable switch member adapted to flex said resilient strip to move the contact block carried thereby into' engagement with one or the other of the contact blocks of said stationar switch members, the contact block carrie by the resilientstrip being formed with two opposed, similar contact faces for such engagement with the contactblocks of both switch members and the contact blocks of all switch members being identical in construction.

4. In double throw-switches, an insulating carrying-plate, a pair of stationary switch-arms secured to and depending from said carrying-plate and havin contact portions one of which is dispose beneath the other, a switch-member comprising a block having two engaging-portions normallyarranged between the contact portions of said stationary switch-members, a crank-shaft,-a rod connecting said crank-shaft with said movable switch-member, a spring arranged on said rod adapted-to be compressed upon a downward movement thereof, and means for rocking said crank-shaft.

5. In an electric-switch, an insulating carrying-plate havin a hole through it and bearing the switc -elements; a plate supported on said carryin plate and arranged to cover said hole, having a hole through it,

i switch operating means including a rod which is extended through the hole in the carryingplate and through a hole in the cover-plate, and a'crank-shaft to which said rod is connected, said cover-plate being slidable on the carrying-plate and on said rod, upon a movement of said rod caused by a turnin movement of the crank-shaft, yet arranged to cover the hole in the carrying-plate in all positions it occupies.

6. In an electric-switch, an insulating carrying-plate having a hole through it and bearing the switch-elements, a plate arranged to cover said hole, having a hole through it, switch operating-means including a rod which is extended through the hole in the carrying-plate and through a hole in thecover-plate, and a crank-shaft to which said rod is connected, said cover-plaicbeing slidable on the carrying-plate and on said rod, upon aniovement of said rod caused by a turnin movement of the crank shaft, yet arrange to cover the hole in the carrying-plate in all positions it occupies,

and a spring arranged on said rod for holdcarrying-plate.

7. In an electric switch, a movable switch ing the cover-plate in engagement with the member having a handle movable both ways from a neutral position, and a lug on said handle, stops for limiting, movement of the handle in said twopositions, and a pivoted latch having a shallow recess to receive the lug on the handle and prevent movement of the handle into the final position, but permit movement thereof into the initial position, and means whereby said latch is adapted to be progressively moved in an upward direction by the handle while the handle is being moved into said initial osition, said handle adapted to be moved romc the initial to final position independently of the latch with such anangular velocity that the downward velocity component of the lug on the handle is greater than that of the latch which is adapted to fall by ravity independently of the handle, to ena%le the lug to pass by the recess of the latch before the latch has engaged the lug and permit the handle to be removed to said final position.

8. In an electricswitch,a movable switch member having a handle movable both ways from a neutral position, respectively, into starting and running positions, and a lug on said handle, stops for limiting movement of the handle in starting and runnin positions, and a pivoted latch having a sha low recess to receive the lug on the handle when in neutral position and prevent movement of the handle into running position, but permit movement thereof into starting position, and means whereby said latch is adapted to be progressively moved in an upwarddirection by the handle while the handle is being moved into starting position, and to be held in elevated position by the handle while in starting position, said handle adapted to be moved from starting to running position independently of the latch permitting said latch to fall by gravity, such movement of the handle, when quickly performed, enablin its lug to pass by the recess in the latch be ore the latch has recngaged the lug.

9. In an electric-switch, a movable switch member having a handle movable both ways from a neutral position, respectively, into starting and running positions, and a lug on said handle, stops for limiting movement of the handle in starting and running posi tions, and a pivoted latch of semi-circular formation having a shallow recess in its outer edge to receive the In on the handle when in neutral position and prevent movement of the handle into running position, but permit movement thereof into starting position, and means whereby said latch is adapted to 'be progressively moved in an upward direction by the handle while the handle is being moved into starting position, and to be held in elevated position by the handle while in starting position, said handle adapted to be moved from starting to running position independently of the latch permitting said latch to fall by gravity, such movement of the handle, when quickly performed, enabling its lug to pass by the recess in the latch before the latch has rengaged the lug.

10. In an electric-switch, a movable switch member having a handle movable both ways from a neutral position, respectively, into starting and running positions, a lug on said handle, a pivoted latch engaging said lug to prevent movement of the handle into running position and permit movement thereof into starting position, and means whereby said latch is progressively movable in an upward direction by said handle while the handle is being moved into starting position, said handle adapted to be moved independently of the latch from starting to running position during which movement the latch is adapted to fall by gravity, such movement of the handle, when quickly performed, enabling its lug to pass by the recess in the latch before the latch has reengaged the lug.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing witnesses.

GEORGE A. BURNHAM.

Witnesses:

B. J. NOYES, H. B. DAVIS.

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