US2173387A - Transformer - Google Patents

Description

G W. BALE TRANSFORMER Sept. 19, 1939.

Filed May 18, 1936 2 Sheets-Sheet 1 s im I nlmll G. w. BALE TRANSFORMER Filed May 18, 1936 2 Sheets-Sheet 2 a 1 Z M a, M 5 z z j W a Q 0 m M fi, i.

M M m Patented Sept. 19, 1939 PATENT OFFICE TRANSFORMER George W. Bale, Springfield, Ill., assignor, by mesne assignments, to Hogan Oliver, Little Rock, Ark.

Application May 18, 1936, Serial No. 80,366

1 Claim.

This invention relates to electric welding and cutting devices and more especially to transformers for electric arc welders.

This application is a continuation in part of my application for patent on Electric welding and cutting devices, Serial No. 41,727, filed in the United States Patent Office on September 23, 1935.

It is well known that in the use of arc welding and cutting devices it is desirable to supply an electric current of high intensity or amperage and at the same time to keep the voltage across the are at a minimum. Machines and devices for producing such a result have heretofore necessariiy been large, bulky and expensive to manufacture. It is the general purpose of the present invention to obviate these objections by producing a machine which is small and compact and therefore inexpensive to manufacture.

It is therefore an object of my invention to provide a simple, practical, and inexpensive device of the character described.

Another object is to provide a device of the character described which is more efficient and more easily handled for portable use than heretofore.

A further object is to provide a device as described which has practically no movable parts.

A further object is to provide a device of the character described in which a considerable variation in the welding current can be provided in a simple and efficient manner.

An additional object is to provide a device which is adapted to be used on a primary source of power of either high or low voltage.

Further objects and advantages will be apparent and brought out more fully in the following specification, reference being had to the accompanying drawings forming a part thereof, wherein:

Fig. l is a partly broken away plan view with the cover removed of a preferred embodiment of my invention;

Fig. 2 is a sectional elevation of the same taken along the line 22 of Fig. 1;

Fig. 3 is an elevation of the primary switch element taken along the line 33 of Fig. 2;

Fig. 4 is a sectional view of the same taken along the line 44 of Fig. 3;

Fig. 5 is a front end View of the casing, showing the various switches and terminal connections;

Fig. 6 is a rear end view showing apertures for the circulation of cooling air;

Fig. 7 is a sectional view taken along the line 7-1 of Fig. 1; and

Fig. 8 is a schematic wiring diagram showing electrical circuits and connections.

Referring more particularly to the drawings, I show a cabinet or casing it generally of rectangular shape and preferably of sheet metal or an equivalent material, having the usual bottom ll, sides 12, rear end wall 13, and front end wall l4, and provided with handles l5 for convenience in moving the device from place to place. A number of apertures 16 are arranged in the side and end walls to facilitate the circulation of cooling air into and out of the casing 10. Within the casing I0 is located a transformer I! which is suitably secured to angle irons 18 by bolts l9 and to the bottom of the casing by bolts 20. The transformer which is shown as being of the shell type is provided with a central core 2| (Fig. 7) on which are wound a secondary winding 22 and a primary winding 23, the core having the usual external portions of laminated iron, of which one end section 2|a is of somewhat larger section than the opposite end portion in order to provide for the dissipation of the additional heat generated therein, inasmuch as the secondary winding 23 has more of its coils Wound near the end Zla than the opposite end, as will be fully understood and appreciated by those skilled in the art. An important feature of my invention consists of a strip 2 lb of mica or equivalent material embedded in the center of the central core 2|. This strip is preferably fifteen thousandths approximately of an inch in thickness and extends in the core the length of the windings and is of the same width as the laminations of the core. The secondary winding 22 is preferably wound with 88 turns and has its end terminals brought out through terminal conductors 24 and 25, which are connected to binding posts designated G and H respectively, which protrude through the front wall 14 but are insulated therefrom. At a point 47 turns from the end of the secondary which connects with the G terminal is an intermediate terminal conductor 26 connected to a binding post L, and similarly at turn 57 is another terminal conductor 21 connected to a binding post I. The primary winding 23 has one of its end coils terminating in a lead 28 which is connected to one terminal of a power switch to be described more fully hereinafter, and its opposite end coil terminating in a lead 29 connected to the 220 volt No. 4 contact of a rotary selector switch also to be described more fully hereinafter. Other intermediate tap leads 30,

3f, 32, and 33 are brought out from the primary winding, and these taps are connected to contacts l, 2, 3, and 4 respectively of the volt portion of the selector switch hereinafter referred to and designated as 43. Additional intermediate primary taps 3d, 35, and 36 are brought out and connected to contacts I, 2, and 3 respectively of the 220 volt portion of switch 43. One layer of turns of the primary winding is next to the core after which comes the secondary, and outside of the latter the remaining primary turns are laid. A double-pole singlethrow switch 3'! is provided and is connected to the leads 38 and 39 which may be connected to an alternating current supply source of either 110 or 220 volts. A lead 60 is connected to one of the terminals of the switch 31 and to a fuse block and fuse 4!, and from the fuse block 4! a lead 42 connects to the center contact of the switch 43. Switch 43 is of the rotary type and is provided with an insulated plate 44 having an aperture aligned with an aperture in front plate [4, through which apertures the plate i l and the switch 43 are secured to the front wall 14 by utilizing a bushing 45 which passes through said apertures and is secured to wall I4 by lock nut 46. Bushing 45 has a central bore 2'! in which is located a rotatable shaft 58, at one end of which is secured an operating lever 49. An insulated contact plate 5i] having a central aperture is secured to the bushing 45 by a lock nut 5|, and it is provided with 110 volt contacts numbered l, 2, 3, and 4 respectively and 220 volt contacts numbered I, 2, 3, and 4 respectively. A switch blade 53 is secured to the shaft 45 and is adapted to make successive contacts with the contacts I, 2, 3, and 4 respectively of the 110 volt and 220 volt portions of the switch, and stops 54 are provided to limit the movement of the contact plate of the switch blade 53.

In Fig. 8 I show an article of work 55 which is to be welded or cut, and a lead 56 is connected thereto and to the secondary binding post G. A lead 5'! is connected to a hand piece 58 which in turn holds a welding rod 59, between which and work 55 the necessary are is made. Lead 57 is adapted to be connected to one or the other of the secondary binding posts designated L, I, or H, as desired and depending upon whether low, intermediate, or high amperage current is desired for this particular piece of work being operated upon.

It is believed that the operation of the device is obvious without any extended comment. When the switch 3! is closed, the primary winding 23 becomes energized through lead 28 and leads if! and 42, the switch blade 53 being in contact with one of the switch contacts. Assuming that the supply power is of 110 volt potential, the switch blade 53 may be placed on either contacts I, 2, 3, or 4 of the 110 volt portion of the switch 43, and in these various positions the 110 volt supply may be impressed upon the different windings of the primary coil of the transformer. These variations will result successively in an increase in the magnetic intensity of the core, and the secondary current will therefore be increased with each successive increase in the primary voltage as determined by these variations from switch connection contacts l, 2, 3, and 4 respectively. The primary winding turns between the end winding connected to lead 28 and the 110 volt No. l are preferably and up to contact No. 2, 220 turns; No. 3, 270 turns; and No. l, 3A5 turns. A similar ratio of turns is provided for connection with the switch contacts I, 2, 3, and 4 of the 220 volt portion of the transformer, the arrangement being such that practically the same secondary current will result from the No. 1 switch contact when used either on 110 or 220 volts, and similarly for the contacts 2, 3, and 4 of each voltage arrangement.

It is thus obvious that variations in the secondary winding of the transformer or output can be obtained either by shifting the switch blade to the different switch contacts or by connecting the lead 51 to either L, I, or II bindin posts or by various combinations of these arrangements. For instance, I have found that with wire 51 on binding post L and moving the switch from contacts I to 4, the secondary voltage will be 38, 28, 1'7, and 10 respectively, with secondary current at 66 amperes with the switch on No. 1 position, the amperage increasing to 178 when the switch is on No. 4 position. When the wire 51 is on the intermediate or binding post I, this voltage variation was 30, 17, 9, and '7 with the switch being shifted from contacts I, 2, 3, 4, with the amperage increasing from 2'70 to 390. Finally, with wire 51 on binding post H the voltage variation was 18, 9, 5, and 3, with the current variation between 420 and 560 amperes.

It is obvious that the decrease of secondary voltage with the increase of secondary output amperage is a necessary consequence of the potential drop or loss to the resistance of the secondary winding with the increase of current, this reduction in voltage being proportional to the square of the increase of current. From the foregoing it will be apparent that variations in output current are possible in gradual steps varying between 66 amperes and 560, which range is satisfactory to cover practically all arc welding and cutting requirements, and that the same may be achieved without the necessity of any cumbersome equipment or movable parts.

I have found that by winding one layer of the primary next the core and by the inclusion of the mica strip 21b in the core as described that a much improved arc is provided, and one that is perfectly satisfactoryfor all types of welding and cutting. The mica strip 2H) produces a condenser-like action in the core and produces a much hotter and more sustaining arc than otherwise. As is well known there is a strong tendency of alternating current arcs to go out and this tendency is very largely overcome by the foregoing features of my invention.

It is further apparent that the various objects heretofore mentioned have been achieved in this novel device.

While I have illustrated and described the preferred form of construction for carrying my invention into effect, this is capable of variation and modification without departing from the spirit of the invention. I, therefore, do not wish to be limited to the precise details of construction set forth, but desire to avail myself of such variations and modifications as come within the scope of the append-ed claim.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

A power transformer for raising the amperage of a source of alternating current adapted to be used with apparatus drawing a heavy current comprising a laminated core including sheets of ferrous material positioned each against the next adjacent sheet and each having a central leg and two outer legs forming when assembled a 75 closed magnetic circuit, a single relatively thin sheet of dielectric material of the character of mica having a length and width substantially equal to the central leg of one of said sheets of ferrous material positioned in the laminated central leg of the core substantially midway between the laminations thereof, and a coil of wire having a length equivalent to the length of said centra1 core leg including concentric primary coils and a secondary coil wound around said composite leg substantially enveloping said dielectric material.

GEORGE W. BALE.

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