US2672578A - Transformer construction - Google Patents

Description

March 16, 1954 L. VERKUIL TRANSFORMER CONSTRUCTION Filed Feb. 24, 1951 Patented Mar. 16, 1954 UNITED STATES PATEN T FICE TRANSFORMER CONSTRUCTION Leo L. verkuil, Norwalk, Conn., assignor to Edwards =Qompany, :Inc., Nor-walk, Conn, a-cor- ;poration.of.New.Yor-k Application=Eebruary 24, 1951, Serial No.212,609

27 rGlaims. (Cl. 317-) :TIZhis invention relates'rtorthe construction and mounting ;of electrical :t-ransformers .and :to .casings :thereior. .application iis :a zrcontinuation-in-part 'of my application 'Serial :Number 'LBGOZ; filed January 19, 319,49, now abandoned.

;More :panticularly, it relates ftO (that itype .of transformer which is :adapted :to :be secured to an toutlet .box 101' ,to be 'TSEOUIBd tO a bracket or cleat on -.a :wall. Generally speaking, the :type of :transformer forzwh-ich the present .invention is :particularlyiuseful :is :the type used to :reduce the voltage :o'f, 'illustratively, the rordinary house lighting supply circuit (1 15 :or '23!) volts) to a lower moltage say, i 6 ivolts or .24 -yolts, for use in a bell-ringing or other signalling system or other low avoltage utility.

:Erior art transformers of the tt-ype with which the present invention .is generally concerned are subject to a number of serious .defects. :Such prior art transformers have been :designed with pedestals attached Lthereto Yfor amounting on a wall bracket or cleat, and expedients have been attemptedso "that, without use -='of the :pedes'tals, the "transformer :may he attached to a standard outlet lbOX and secured "thereto. However, when attached :in this -manner Iit has ibeemposs'ible that some portion of the'itransformer is closer *to the wall or other structure-on which the outlet box is mounted 2 than isconsistent with: safety, I-having in consideration .the hazard from lfire. For example,Underwriters Laboratories,Inc., th'e recognized; authority son the construotion and installation of :olevioes *which under some circumstances may :become fire .ha-zards, has specified a minimum distance .fromanytpart'ofia transformer so mounted to the :nearest -wal1. l hat authority prescribes :the :standard :minimum distance for transformers rofithe above-described type as onequarter of an inch.

An object of the ;present inven'tion is to pro-, vide :a transformer construction which has a mounting :pedestal iintegral with :the casing :02? the transformer and which is -.capable of being readily interrelated with a standard outlet box, but cann'ot be :mounted 'or secured ito it in any position with-out maintaining a :minimum predetermined clearance between the transformer :itself and the wall upon which the :outlet :box is mounted.

.iAnother object is to :provide .a transformer construction in which theam'eans for mounting it on :an outlet box 531 8 of simple land readily Efabricated {construction and -simp1e.=and 'JCOIIVBHTEIIC to manipulate, and, edesirably, have mo parts such as =bdlts :or muts which must :be removed Gil 2 when 'cmounting it, yet assures that ithe :transformer is tightly and positively secured Eto rthe outlet box.

.Another ObjGCtzlS to :provide suchrattransformer construction which is easy :and economical ito construct and .to install and \which has Einherent safety in use. Another object :is to ":provide a transformer construction :in which the meavy lead wires, such as those that :are to be connected inside the outlet box, are strongly :and dependably anchored and well :adapted :to :resist pulling thereof or strains :thBI'BOIl. .AIIUthEriOb' ject is to provide atransformer of athe just-unentioned ttype embodying, in a compact :manner and capable of ease of assembly, :a temperatureresponsive cut-out which :may also :be 'adapted to serve as :a lead-in anchorage :and which may be ;constructed in a 'manner readily to :compensate for possible strain :imposed ithereon during assembly.

:Other objects will :be in part tobvious :or 'in part pointed (out "hereinafter.

The invention "accordingly :consists in the zfeatures ;of construction, combinations ooi elements, and arrangements of :parts as will she aexemplified in the structure :to the :hereinafter described and the scope of the application :of which will be indicated iinithe following claims.

:In the accompanying :drawing in which :is shown an illustrative embodiment of ithis invention and in which similar reference characters :re'fer .170 :similar "parts throughout,

Figure ,1 .is a perspective view :of :the transformerstructure :and :of an outlet :box, showing the .iformer in .a position ready to be secured to the :outlet 'zb'ox;

.Ei'gure i2 is :a plan :view :as seen along the zline 2-+2 of Figure :1, with the 'outlet .b'ox :shown tin horizontal section, showing the transformer structure assembled to wthe outlet .abox, an .in relation :to the "wall or other supporting -surfaoe to which the :outlet bnx is secured;

Figure .3 :is ansendoelevation zof the transformer structure .as it would rbe seen from the :left iin Eigure 2 :prior =.to its assemblageito the "outlet ib'ox';

Figure A is a plan :view 50f sthe transformer structure as .seen with :a portion of tits ceasing structure zremoved;

rzli'igures *5 and 61are transverse :sectional 'aviews as seen a1ong'the;line;AxA :ofsFigure lpfihowing by way of illustration two forms iofspreader aarrangements for icertainof the transformer idasing parts;

anigures :7 and 1:81am yplan views mes,pectmelt of ea sheetemetal -.conductor rclamping plate and of a coacting insulating plate which are assembled and related to the core and winding as shown in Figure 4;

Figure 9 is a detached side elevation, seen from the left of Figure 4,. of a temperature-responsive switch structure, and

Figure 10 is a vertical sectional view as seen on the line 8--8 of Figure 9.

The transformer comprises a core C, illustratively laminated and of any usual form, generally rectangular in outline as shown in Figures 1, 2, and 3, and a casing AB Which-has bulges in its sides to accommodate the interior windings associated with the core C. Illustratively, the windings, as in known constructions, can extend about a middle leg of the core and through core windows, as indicated in Figure 5, where the windings are indicated by the reference character W.

The transformer casing A-B is preferably made of sheet metal, thus to facilitate stamping operations to produce and shape it, and in the illustrative embodiment it comprises two halfhousings generally indicated by the respective reference characters A and B. Each half-housing is stamped or shaped to the respective conformations hereinafter described and they can rest, as shown in Figures 1 to 3, against the rcspective side faces of the core C; half-housings A and B and the laminations forming the transformer core C are clamped together by any suitable means, such as bolts Ill and nuts I I, which enable the casing to be taken apart if desired. Rivets or clamps may be used instead of bolts and nuts for this purpose.

Half-housing A, as is better seen in Figures 2 and 3, has a bulging or dished-out central portion l2 of substantially rectangular configuration, with rounded edges and corners, and as seen in Figures 2 and 3, the central portion It extends upwards from a flat marginal or base portion I3 which rests against one side face of the core C. As shown in Figures 1 to 3, the bolts pass through this marginal or base portion of using A. In Figure 2 is indicated a dimension a which indicates the maximum depth of the bulging or dished-out portion l2, being the distance from the inside face of the base portion l3 to the outside surface of the dishedout portion [2, which surface (Figures 2 and 3) is flat.

Half-housing A has an extension H, to the left in Figures 1 and 2 and toward the observer in Figure 3, which is formed integrally with and as part of half-housing A, is slightly tapered as shown, and it ends in a substantially semi-circular ring-like flange [8; as shown in Figure 2, it overhangs one end face of the core C; its lower overhanging edges (Figures 2 and 3) are substantially in the plane of the inside face of the base portion l3, which plane is coincident with the plane of the core face against which the half-housing A rests. Also, as appears in Figure 3, the extension ll overhangs an end of the core C substantially at its midpoint. The center or axis of the semi-circular ring-like flange [8, while falling substantially in a vertical plane through the center of the core C as viewed in Figure 3, is displaced or offset vertically from the horizontal plane through the center of core C.

The right-hand portion of the tapering extension I! as seen in Figure 2 overlies the upper face of the left-hand leg of the core C, providing ample passageway for the input leads [6-46, usually heavily insulated as shown, and they can thus overlie that transformer leg, as is shown also in Figure 5; these leads, in the illustrative embodiment, are the ones that are to be connected to the building lighting circuit, usually of about volts, and they are connected in any suitable manner to the high voltage coil of the windings W, illustratively as indicated in Figure 5.

Just behind the half-ring flange I8 as viewed in Figure 3 and to the right as viewed in Figures 1 and 2, the extension H has a semi-circular depressed portion I! (Figure 2) which is of lesser radius than the portions of the extension l1 to either side of it.

Half-housing B has a dished-out portion l9, in general similar to the dished-out portion I2 of half-housing A, having a base or marginal portion 23 that rests against a side face of the core C where it is held by thebolts II]. In the dishedout portion is is a generally centrally located opening adapted to securely hold a flat piece of insulating material which serves as a terminal panel 20 provided with binding posts or screws 22, illustratively two in number, to which output leads 2| may be attached; the binding posts 22 are connected internally of the transformer structure and in any suitable manner to the low voltage coil of the windings W, that coil supplying lower voltage, illustratively 6 volts or 24 volts.

In Figure 2, on the half-housing B, is indicated a dimension b, which represents the depth of the dished-out portion 19, that is, the distance from the inside face of base or marginal portion I3 to the outside face of the flat wall of the dishedout portion l2.

At the left-hand end of half-housing B as viewed in Figures 1 and 2 and at the forward end as viewed in Figure 3, half-housing B has a tapered extension 26 formed integrally with and as part thereof; similarly to extension I! of half housing A, extension 26 terminates in a semicircular ring-like flange 21 and adjacent the latter it has a depressed portion zfi -of lesser radius than those parts of the extension that are to either side of it. The lengths of extensions l1 and 26 are the same so that they project beyond an end face (the left-hand face in Figure 2) of the core C by the same distance.

Unlike extension I! of half-housing A, which is attached to the latter throughout its semicircumference, extension 26 of half-housing B is cut away from half-housing B except for a small portion of its semi-circumference, and because of the above-described offset of extension I! of half-housing A (see Figures 2 and 3), this relatively small uncut portion is left, as indicated'at 39 in Figures 2 and 3, along the line of the-outer edge of the base or marginal portion 23 of the half-housing B, so that the semi-circular tapered extension 26 can occupy a position where it is complementary to the extension l1, namely, in the angle (see Figure 2) between the end face of the core C and the overhanging extension I! of half-housing A. When the parts are thus assembled, semi-circular or half-ring flanges l8' and 21 form a complete circular opening (see Figure 3); together, the-extensions l1 and '26 form a tubular projection from the bulk of the assembled structure, of substantially circular cross-section, and because of the above-described taper in each extension, this tubular projection decreases in diameter as its length increases and it terminates in a subdivided annular flange made up of the semi-circular flanges l8 and 21 with the intervening short section of reduced radius which is :made .up of the two above-described miepii'essed semi-circular portions 11 and 2 6 which together, in effect, form an annular :groove. Moreover, the center line or axis (of this tubular projection or tube-like extension 1-4-6 is offset ("see Figure 13) from "the horizontal 1midplane of the transformer structure (see :also Figure 2)..

,Moreover, the complementary extensions H and '26 dorm a substantially circular channel through which the input leads l B-ilt may pass from the inside of the casing "to the exterior thereof. ltn the circular opening formed :by the flanges It and 2? is placed an insulating .disc as with holes to accommodate the input leads :15; as shown in Figure 2, the semi-circularnanges i 8 and 21 are externally convex, forming a smooth rounded-over exterior and, being externally coonvex, the hang-es 1B and 2-1 arethereby internally recessed throughout theirrespectiv-e arcuate extents, each about ltlo'degrees as shown Figure 3, and insulating disc 2%, as is better shown in Figures '2 and 3, is seated in these complementary arcuate recesses which thus coact to hold the insulating disc 29 transversely of the axis of the tapered tubular ex-tension formed by the comfilamentary extensions I'l' and 2'6. Also, as shown in Figure 3, the holes -indisc 29 are "spaced apart by a substantial distance and they thus, also, insulating-1y hold the "input leads -l-E-lil correspondingly spaced apart.

The sma il'uncut portion 39 (Figure "3) through which the extension 26 remains joined to the halt-housing B, acts like a hing-e and allows the half-ring flange 21'1'20 be displaced substantially radially a direction in line with its "vertical radius as seen in FigureB), relative to C02. p'lementary half-ring flange 18 on the compile mentary extension 11. The complementary extensions i7 "and 26 may thus be spread apart and the tubular extension -I!'2-6, in effect, expanded at its outermost end, and in "the specific illustrative embodiment above described, the connecting portion 38 "between extension 26 and halfhousing 33 being flexible, the "expansion takes place in the direction of the vertical diameter as seenin Figure 3.

Suitable spreader means are provided, preferablyin the former a-screw-or'bol't 3-! that passes through a threaded hole 2t inex'tension Z5 and which is anchored at a point in extension i"! that is opposite the threaded hole in the extension 26, whereby "upon turning of the screw 'or bolt, as by ascrew-driver Where it has a slotted head as shown, the extensions are "spread apart, the tubular extension 15-26 being deformed, at its outer end, by enlargement along -the vertical diameter as viewed in Figure 3. Enterioriy or" the tube-like extension FF-2t, the boil: or screw 3"] is sheathed "in a sleeve '32 of insulating material as shown in Figure '2 "(seealso Figures '4, 5, and in order, as appears from Figure 3, "to insulatingly by-pass the insulated input leads l6-*l5 and between which the bolt '31 extends, the spaced holes in the insulating disc rs enacting to hold the insulated conductors "it-4t spread apart so that, within the tubular extensions Ill- 26, each can :pass -to one side "of the bzciltfBl.

For purposes of assembly in course "of "marmfa'cture, there are many "advantages 'in offsetting the tubular extension I l'26 so 'thatits horizontal median plane as viewed in Figures 2 and 3 coincides with the plane of the upper face or the core (I; as seenin Figure 4, assembly and conneotion oi the heavyiihighvol tage leads l s-4 6 are greatly facilitated; However, :a disadvantage lies in the that :a direct :pull, to :the flight in Figure 4, :on the external ends of leads iii-16 might impose an undesired and detrimental strain on the internal electrical connections with the usually very thin wires of the high-voltage winding, with .the risk of :nupturing them. Accordingly I make provision for overcoming such risk so that pulling on the leads tit-iii to make the cormection :to "the parts Within the outlet box D can be safely eflec'ted, and this I carry out in a manner 'to achieve anchorage even though the transformer structure has embodied it a temperature-responsive safety cutout as it at times desirable or "prescribed.

in Figures '4 land 9, I have shown :a preferred form of temperature-responsive cut-out. comprises :a heavy "fiber plate-like support All having a downward extension 42 that extends into the left-hand core window 43 o'f'the core C. The latter is of the shell type, having a middle core leg 34 which passes snugly through the windings W and the heavy fiber winding end plates 45--4B that are substantially octagonal, shapedso their right-hand vertical-edge faces, as seen in Figure 4, abut against the inside fac'e'or" the right-hand core leg and their left-hand vertical edge faces are spaced from the inside face of the left core leg by a distance equal to the thickness of the fiber support 4'1; the latter rests against the left-hand vertical ends of winding plates 15-45 with its downward extension 42 snugly fitted into the space between the left core leg and these vertical plate ends. "Ihefiber support M is thus mounted and held to resist forces transversely of its plane, particularly forces to the right in Figure 4. Its ends overlie the core C and its upper edge (Figure 9) may be conformed to the shape of the inside face of the bulging part of half-housing A so that when the latter is assembled to the core!) and its counterpart half-housing B, as by the bolts Iii-H3, fiber support 41 'is securely clamped between housing part A and thecore C.

Fiber support t! carries 'a'thermally-responsive switch structure which comprises two elongated flat metal parts it and it, each on one side of support' ii, to which they areclamped at one end by a hollow rivet or eyelet 5d so as to extend toward the other end where they overlie an aperture 5| (Figures 9 and 10). A combination Washer and bushing ll of insulating material insulates part it from the eyelet do and part 48. One of the parts, 4?, has an area or portion 47 illustratively circular, that is stamped or pressed out of its plane so as toprojectinto the aperture 51, acting as a guide to resist any tendency of part ill to swing, about the rivet 59, out of juxtaposition to the other switch part &8. The latter is prevented from swinging about the rivet 5'!) by an extension til that is bent into a cut-out ll in'support ii. The free ends of parts ll' l8 are thus maintained opposite each -other,at the aperture at, where each, as shown in Figure 1 0, has a "contact'point of suitable alloy for engagement with each other to close an electrical circuit. Intermediate its ends, support M has a large aperture '52 which extends above and below the plane of the upper face of core C as viewed in Figures '3 and i and thereby substantial lengths of the switch parts ii-58 are insured of-exposure to the temperature created inside the housing A--B by the operation of the windings Wand .by heatloss es in thacore. 0.

{one "of the switch parts, such as part :48, is

bimetallic so that, being clamped by eyelet 50 at one end, it bows, upon increase in temperature, in a direction to move its other end away from the plane of support 4| and hence away from and out of contact with the end of companion switch part 41 exposed in aperture 5|, thus breaking the circuit at the contact points. When connected in circuit with the high-voltage coil of windings W, the circuit can thus be broken upon temperature rise due to overloading. Switch part 41 is provided with a tab 41 to which the thin lead wire from one end of the high-voltage winding is secured, as by wrapping and soldering, after passing it through a hole in end plate 45 of the windings W. One of the heavy lead-in conductors IE, after stripping its end of insulation, is projected through the eyelet 50, then bent over, and soldered to the eyelet. Pull or stress exerted on that lead-in conductor I6 is resisted by the rigidly clamped fiber support 4| and is not exerted on the thin lead from the coil; were plate 41 to yield, it would yield to the right in Figure 4 and could not tension the thin lead-in from thecoil. However, provision is also made to relieve the fiber support 4| from substantial stresses in that the lead-in connected thereto may be held in a manner about to be described.

Resting upon the upper face of middle leg M (Figures 4 and 3) is a suitably heavy sheet-metal plate 54 (Figure 7 provided with end tongues 55-55 and overlying it is an I-shaped plate (Figure 8) of insulating material, of the same width but longer, being cut out at Ii"! and 51 both are tightly held and anchored between the leg 45 and windings W, being put in place upon assembly of pre-formed windings W to the middle leg M1 with the fiber sheet 51 toward the inside of windings W. Tongues 55--55 are bent upwardly into the cut- outs 51 and 51 of the insulating plate 51, preventing relative displacement between the two.

Where the transformer includes a cutout 41-48 as above described, and to which one of the heavy input-leads |t is anchored, that lead is passed over the insulating plate 51 and between the tongue or lug 55 and winding end plate 45, as shown in Figure l, whence the tongue 55 is bent over it to clamp it tightly against the anchored metal plate insert 54, with the fiber plate 51 interposed. Thus the fiber support is protected against the effect of substantial stress that might be imposed on th lead-in. The other input-lead iii. or, in case the structure does not include the cut-out switch 414t, both inputleads |"5-|6 are secured in the manner now described with respect to the lower lead H; as seen in Figure 4.; the heavy lead is first bent back upon itself to form a hook H, the short end of which is inserted between the then-upstanding tongue 56 and winding end plate is, whence the tongue 55 is bent over it and forced home toward the metal insert plate 54 to clamp the short end between tongue 56 and the metal plate 54 with the insulating plate 51 interposed therebetween. The resultant anchorage is strong and does not slip, for the heavy lead is hooked around the tongue and the tongue clamps and holds the short end of the hook against unbending and without unbending no slipping takes place. No stress is transmitted to the thin high-voltage coil lead wire which, after passing through a hole in end plate 46, is soldered to the bared wire of short end of the hook H.

When the fiber support 4| is clamped between the core C and half-housing A, strains are frequently set up in the part 4| and it is sometimes distorted so that an initial setting of its bimetallic part for functioning to open the circuit at the desired temperature is disturbed. This is in part counteracted by the provision of the apertures 5|-52 which remove a major part of the fiber support 4| from inbetween the switch arms 41--48, giving their major portions a sort of freefloating effect. Upon final test-checking, however, when assembly is completed, any departure in setting is corrected by an arrangement that does not require taking the half-housings apart. In switch part 48 is threaded a screw 58 whose free end abuts the fiber support 4| (Figures 4 and 9), and in half-housing A I provide a small round hole 59 (Figures 2 and l) which is coaxial with the axis of the screw 58. A small screw-driver inserted through the hole 59 serves to turn screw 58, which is close to the eyelet support 50, to strain the switch part 48 in a direction toward or away from its companion switch part 41, as the case may be, to effect circuit-opening at the de sired temperature. The structure is then ready for installation.

The above-described floating form of support for the coacting ends of the parallel switch elements 41-48, furthermore, serves to tend to preserve the temperature setting should the lead-in wire l6 anchored to the composition fiber or plastic support 4| strain the latter; any stress causing such strain is imposed on support 4| at the eyelet 50 by which elements 41-48 are secured, and such strain does not disturb either element relative to the other and, at the most, shifts the two as a unit, and this action is aided in that the intervening portions of support plate 4| are cut away so as not to impede such shifting.

The inner end of the spreader bolt 3| bears against the rigid extension H at a point opposite the threaded hole 26 in the movable extension 26 and is suitably anchored in the extension |1. In one form the bolt 3|, at the end opposite its head, is anchored in extension [1 part-way along its length so that turning the bolt 3| spreads extension 26 away from extension H or draws it toward extension |1, depending on which way the bolt is turned. An illustrative arrangement of this kind is shown in Figure 6, where an intermediate portion of the bolt passes through a hole, which thus forms a seat or socket, in a depression in the wall of extension l1, its end is externally headed over, and such arrangement anchors the free end of the bolt against sidewise displacement under the stress of spreading one extension away from the other. Or the bolt may be anchored against such sidewise displacement, by simply having its inner end portion seated in an internal recess or seat in the wall of extension H at a point opposite the threaded hole 26 in the extension 26, as indicated in Figure 5, where the internal seat or socket is formed in a depressed portion of the sheet metal of the extension l1.

Standard outlet boxes, such as is shown at D (Figures 1 and 2), consist of a back wall 33, four side walls 34, 35, 36, and 31, and a cover plate (not shown). The walls are provided with knock-outs seated in the several openings 33 that are usually provided in each wall (only one is shown in the back wall in the interest of simplicity); these are of the usual type and, as is.

known, any one or more knock-outs may be removed to expose and make available the desired hole or holes through which the wiring a scissa oi the1'building: circuit; or circuits is usually brought into: the: outletbox. for electrical interconnection. In standard outlet boxes, the dis.- tances: from. each of the: openings or holes 38 in. the. side-walls 34', (E'r,. 3 t.,v and 31* to: the back of the backwall. 33- is; fixedi and invariable, and when the: box. is. secured with; its back wall 33 against a. wall surface. or wall; 39; as. by screws 40 (Figure. 2);, these openings 38 in; the; side walls are all spaced; from. the face. of; the wall Bit by the. same. invariable distancev which, from the. center i of. the. hole 38. to. the face of" the wall 38-, indicated. in Figure 2 by the dimension or Safety rules against fire hazards require that in. mounting atransformer in relation to,.a surfacemounted. outlet. or panel box for connection of its high voltage terminals to. circuit conductors within the box, the transformer must not, be given a position relativev to: the wall 39', which is: not infrequently a wood panel, less. than a prescribed minimum, for example, one-quarter of an: inch. In Figure-2 a. dimension d indicates: a spacing of the. transformer from the wall 39 bya distance not less than the required minimum for safety. Illustratively, the distance 0, beingthe spacing of the. centers. of the side Wall holes 38 from the face of wall 39, may be seven-eighths of an inch. According to. certain features of this-invention, it. is possible to make certain that the transformer cannot be. assembled to the outlet-or panel box without meeting at least the minimum safety requirement of spacing of the transformer fromthe wall 39.

As above noted, the depressed halfecircular portions H and ZEi of the extensions. I51: and I 25 together form an external annular groove or neck, and as appears from Figures 1 and 2, the radius of' this annular groove is commensurate with the radius ofa hole 35 in the outlet box, one of which holes (the center one in the wall 35' of Figure 1) is shown with its-knock-out removed and hence with its ring-shaped wall exposed, the width of the latter being about the same as the thickness of the metal of the side wall 35.

The longitudinal axis of the tube-like extension Il'--2'5 lies substantially in the plane of the upper face of the core C, as viewed in Figures 2 and 3-, and against which face the half-housing'A rests;- as'appears clearly in Figures 2- and 3', all parts of the transformer structure that extend upwardly from or beyond this upper face of core C and hence extend upwardly from the longitudinal axis of the tubular extension IT-26, fall within the dimension :1 (Figure 2) which, where dimension 0 is illustratively seveneighths of.v an inch and the minimum value of the spacing dimension d is one-quarter of an inch, is five-eighths of an inch. But, as seen in Figure 3, all parts that extend to theright or to the left of the vertical plane through this longitudinal axis of the tubular extension 26, extend; beyond that axis materially more than the sum of the dimensions a and 01. Also, all parts that extend below, in Figures 2 and 3, the horizontal plane through this longitudinal axis of. the tubular extension, have an extent greater thanthe sum of the dimensions a and d. Though, because of symmetry of internal construction in the illustrative embodiment, dimensions a and b in- Figure 2,, being the respective depths of the dished-out, portions. 12 and IQ of the half-housings. A and B, respectively, are equal, the offsettingof; the. half-circular extension I! upwardly toward the. horizontal plane of the fiat face:- of the. dishedeout, portion. l2 and the oft: setting upwardly. and in: the same direction. (Figures 3; and. Z) of, the half-circular extension 2.5 from the fiat face of the, dished-out: portion l9 are such, that, in the illustration, the dimen: sion. a; (Figure- 2) is less than the dimension 0 by at least the dimension, ti, and the dimension 1 (Figure- 2-)-. exceeds dimension 0.

Accordingly, and asrseen; in- Figure 3, the long i tudinalaxis of. the tube-litre extension H72 6, is spaced. from. thetwo-pa-rallel sides of the structure (being, inI effect, the left. and right-hand side-faces-of the coreC. in. Figure 3) by adistance greater than the dimension. 0, and. is spaced; from the. plane of the bottom face of the dished out portion. t9 of the housing part B alsoby adis-tance greater than the dimension 0, butis spaced. fIom the-opposite-or upper, parallel face of the dishedoutportion l2 of thehousing part A by: a distance that. is less than the me si 0.- by an. amou t at least equal to. the; safety dimension d. 'Ijhat means that. the transformer structure can have its tube-like, extension l-'I2B. entered into the open; hole- 38; in thesidewall 35 of the outlet box I) only when the. half-housing part A; with its half-circular extension I"! is brought to, face the wall 39.

The input leads. LET-t6, arefirst entered through the; open hole; 331 and thereupon the sub-dimmed tube-like extension, 6 1725. is entered into the open hole 3118: through which the half-circular roundedmver flanges t8, and. 21 just about, pass, withthe extension Minot spread, away. from extension 55?, which; is-.-the position of the 13. 1. 28 as shown; in Figure. 3: nd. in which position the flanges l8 and, 21 form. a complete circle, as above noted. As indicated. in Figure 2, the tapered Walls oftha extension; lite-216. are such that they limit, the entry;- of the; tubular extension lp1-.--2-6 into the hole 38,. to a point where the annular groove f med by e. d p ss d p io e and 2 6? are in; juxtaposition to the ring-likev wall of the hole. 3.8, whereupon the bolt 3| is; turned. to spread extensions, H- and 2,6.so. thatthe dehressed or grooved portio s tl andzfi are forced; radially apart and against the edge-like wall of thev hole 3.8-. he p ea i act on: us-ac iered expand the roundedrover flanges t8, and 2 1., to, the left or on the inside or the, outlet box wall to (Figure to.v a dimension greater than. the fixed, dimension of, the hole: 38:. The transformer structure is; thus; firmly.- secured; to; the wall 35. of the box and is firmly heldplace. Thereafter the necessary wire connections are. made tothe input leads l(i|tf. It is to-be-noted that the transformer structure may thus. be mounted in position quickly andwith; a mining-um of manual operations and that what. operations are performed to. secure. it in place are carried on outside of the box D, excepting: for making. the wire connections. Moreover, at least the minimum required spacingof the strueture'from the wall 39 is practically automatically achieved.

he appears from Figures-v 1 and 2, the head of thescrew 3 I; is exposed at'that face or side of the transformer structure that is opposite that face which, for safety reasons, it is desired to have spaced from though facing toward. the wall 39,

and. thus theonly position from which the screw head. is most conveniently accessible for spreading the sub-divided gripping parts is the one which gives the desired spacing of the structure from the. Wall.

The amount of spreading, at the outer end portions of the tube-like extension I'm-26; to

, l1 tightly secure the structure against the walls of the hole 38, need not be very great, as appears upon comparing Figure 3 (unspread) with Figure 2 (where the parts are spread apart), and the spreading action, which takes place by a slight counter-clockwise pivoting of the extension 26 about the hinge-like bending of the portion 30, is accompanied by a tilting of the plane of the half-circular flange 21 out of alignment with the plane of the companion half-circular flange [8, as shown in Figure 2; the insulating disc 29 thus remains dependably held within the companion half-circular recesses in the flanges 18 and 21, being in effect gripped by the side walls of these arcuate recesses because of the justmentioned relative tilting that takes place, all as shown in Figure 2.

The transformer structure, however, is adaptable for alternative methods of mounting independently of the outlet box and also within known safety regulations, and accordingly halfhousing A is provided with a downward extension (Figure 1) below the core C, being integral with the base or marginal portion l3 and at its lower end being bent outwardly at approximately a right angle to form a flange or pedestal 14 provided with holes or slots IE to accommodate screws, bolts, or other fastening devices. Companion to the pedestal I4 is a similar and juxtaposed downward extension (Figure 1) of halfhousing B, from the base or marginal portion 23 thereof, being bent outwardly at right angles to form a pedestal 24 with holes or slots 25. Pedestals I4 and 24 are in the same plane, and

as better appears in Figures 2 and 3, they extend 1.-

from the base parts I3 and 23, respectively, by a distance approximately the same as the depth of the dished-out portion l2 and dished-out portion 19, respectively, of the housing parts A and B. By means of these pedestals the transformer structure may be secured to any suitable support.

These pedestals do not interfere with the desired mounting of the transformer structure to an outlet box as above described, and they can simply be disregarded when such mounting is effected. Desirably, and as above indicated, where the transformer structure has a face toward the wall 39 that is flat and of substantial area, as is the case with the flat portion of the dished-out portion 12 of the housing part A, such face is parallel to the wall face 39 so that the spacing distance d is uniform throughout, and thus a safety spacing from the wall face 39 at all internal parts of the transformer that generate heat is brought about. As is known, it is the windings and the core C which can become unduly heated, as from overloading or a defect in a circuit somewhere.

I may, however, make provision to guard against installing the transformer initially with its back face out of parallelism with the wall 39, or to guard against possible shift of the structure out of such parallelism. Thus I may provide the transformer structure with suitable relatively small and spaced elements that are engageable with the face of the wall 39; these may comprise lateral tongue-like extensions l4 and l4 near the respective ends of the right-angled ange i4, and as shown in Figure 2 they extend beyond the dimension 1: by a distance which need not be greater than the minimum safety dimension d. Spaced upwardly from the plane of these extensions I4 and l4 are two extensions [3 and l3 that are integrally formed with a right-angled extension l3 (see Figure 1) of the upper portion of the base or marginal portion 23 of the halfhousing B and which overlies the upper face of the core C; extensions I3 and 13 project beyond the rear face of the core C by a distance equal to the sum of dimension 0. and safety dimension d.

The outer edges of all four extensions I4, I4 i3, and l3 fall in a plane which is parallel to the axis of the extension "-26, being spaced therefrom by the distance 0; this plane substantially coincides with the face of the wall 39 when the transformer structure is secured to the outlet box D and the extensions engage the face of wall 39 at sufficiently spaced points to insure that no such tilting of the transformer structure about the longitudinal axis of the tubular extension I126 can take place as will make the spacing of any heat-generating part of the structure less than the desired safety distance. These extension members can be brought safely into contact with the wall 39, for the purposes just described, because they are not directly subjected to any heat that might be generated internally of the transformer, and being preferably made integral with the sheet metal of the transformer casing or housing and extending away from the latter, they are relatively thin and in effect act to radiate or dissipate to the atmosphere any heat that might reach them by conduction.

These four tongue-like extensions are scored along the lines indicated at S, whereby they can be broken off if they are not needed in particular installations.

It will thus be seen that there has been provided in this invention a transformer construction and mounting therefor in which the various objects of this invention, together with many thoroughly practical advantages, are successfully achieved. Economy and ease of manufacture of the transformer housing and of its assemblage to the core structure are achieved; for example, the casing or housing may be made up in the form of the two half-housings A and B, utilizing two pieces of metal stock, such as steel or any other suitable metal, and each of these is subjected to a simple series of appropriate stamping operations and assemblage thereof to the other parts as above described effected to complete the transformer structure. In installing it, the operations are simple and speedy and can be carried on with complete safety, having the additional advantage, also, that installation can be effected without having to contend with loose parts.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing is to be interpreted as illustrative and not in a limiting sense.

I claim:

1. In construction of the character described, in combination, an outlet box having a back wall to rest against a supporting surface and side walls and having a round aperture in a side wall thereof spaced from the center of the aperture to the plane of the back wall of the outlet box by a distance r, a transformer structure having a core and coacting windings and an enclosing casing therefor presenting four side faces, said casing having a tubular extension the axis of which is parallel to said four side faces of the transformer structure and is displaced from three of said side faces by a distance greater than a: and from the fourth side face by a distance less than a: by an amount providing a factor of safety against fire hazard whereby the axis of said tubular extension half housings and has conductors extending therethrough to said winding means, and an apertured insulating disc substantially closing off said tubular extension and having said conductors passing therethrough, each of said half-circular extensions having axially spaced means of substantially 180 degrees extent for respectively receiving therebetween opposed peripheral portions of said insulating disc, each of substantially 180 degrees extent.

14. A transformer construction for mounting in the round aperture of a support such as an outlet box or the like comprising a core and coacting winding means and a casing therefor, said casing having a tubular extension communicating with the interior of said casing and having conductors extending therethrough from said winding means, said tubular extension being subdivided into opposed arcuate end portions whereby the latter are receivable in the round aperture of a support and being substantially closed by an apertured insulating disc through which said conductors pass, said end portions having flange-like means directed inwardly for holding said insulating disc, and means for spreading apart opposed arcuate portions that are at opposite ends of a diameter without material spreading. apart of arcuate portions thereof at opposite ends of a diameter that makes a right angle with said firstmentioned diameter and thereby maintain the holding action on said disc by said flange-like means.

15. In construction of the character described, in combination, a transformer core of the shell type having windings thereabout, a casing comprising two half-housings for enclosing said core and windings from opposite sides of said core, a thermally-responsive switch comprising an insulating support and two substantially parallel opposed conductive switch elements with means insulatingly securing one end of each at one point in and to said insulating support whereby the other ends thereof are free for relative circuit-controlling movement, said support having means securing it in fixed relation to said core and said half-housings having juxtaposed complementary half-circular extensions which together form a tubular extension for the passage of a conductor therethrough, and a conductor extending through said tubular extension and anchored to said insulating support at a point substantially coincident with the point at which said switch elements are secured thereto.

16. A transformer construction as claimed in claim 15, in which said insulating support comprises a plate-like member having a portion extending between said windings and a part of said core with its plane at right angles to the axis of said tubular extension, said switch elements being on opposite sides of said plate-like member and the securing means for said switch elements comprising a hollow clamping means having said conductor extending thereinto and secured thereto, said plate-like member having portions thereof in between said switch elements cut away whereby the free ends of said switch elements can move as a unit under straining of said plate-like member at said securing means.

17. In construction of the character described, in combination, a transformer core of the shell type having windings thereabout, a casing comprising two half-housings for enclosing said core and windings from opposite sides of said core, said half-housings having complementary half- .circular extensions forming a tubular mounting extension, and a relatively heavy conductor passing through said tubular extension and having its inner end bent into a hook, said core and windings having secured thereto a clamping lug that is bent over the short end of the hook with the axis of bending substantially parallel to the axis of said tubular mounting extension and to the line of said conductor.

18. In construction of the character described, in combination, a transformer core of the shell type having windings thereabout, a casing comprising two half-housings for enclosing said core and windings from opposite sides of said core, said half-housings having complementary half-circular extensions forming a tubular mounting extension, the axis of said tubular extension extending at right angles to the axis of said windings and the core portion therein, and two relatively heavy lead-in conductors extending axially through said tubular extension and transversely of the axis of said windings and terminating in hooks at the respective ends of said windings, said windings and said core portion having interposed therebetween a sheet-metal strap terminating at the respective ends of said windings in bendable lugs respectively bent over the short ends of said hooks with the axis of bending substantially parallel to the axis of said tubular mounting extension and to the line of the conductors therethrough.

19. A transformer construction comprising a transformer core having windings thereabout and enclosing casing means therefor, with means for clamping the latter and said core together, a thermally-responsive switch comprising an insulating plate-like support having an edge portion seated against said core and an opposed edge portion engaged by said casing means whereby said insulating support is clamped between the two, asid insulating plate-like support having two relatively long substantially parallel opposed conductive switch elements in circuit with said windings and having means insulatingly secured one end of each to said insulating support at substantially the same point in the plate-like support and having the free ends thereof juxtaposed to each other for relative circuit controlling movement therebetween, whereby, should said plate-like support be strained and the portion thereof at which said switch element ends are secured be distorted out of normal relation to the rest of the support, said other ends of said long switch elements are shifted together substantially as a unit.

20. A transformer construction as claimed in claim 19 in which said parallel switch elements are on opposite sides of said plate-like support, the latter having portions thereof in between said switch elements cut away to provide clearance space for relative circuit controlling movement between said free ends of said switch elements and for movement thereof as a unit.

21. A transformer construction comprising a core and windings and having mounting means projecting therefrom comprising two substantially half-circular sheet material parts which together form a hollow annulus and means supporting said two half-circular parts in complementary juxtaposed relation to form a hollow annulus comprising means rigidly mounting one of them from said core and means supporting the other from said core and having hinge-like connecnection to said other part thereby to permit movement thereof toward or away from the other halfcircuiar part to change the spacing therebetween and to enlarge or shorten a diametrical dimension of said annulus, a conductor extending from said windings through said hollow annulus, and means coacting between said two parts for con trolling the spacing therebetween, whereby said annulus with said conductor may be entered into a round aperture in a support and clamped against the peripheral walls thereof.

22. A transformer as claimed in claim 21 in which said last-mentioned means comprises a screw having threaded connection with one of said half-circular part and engaging the other.

23. A transformer as claimed in claim 22 in which said screw extends substantially diametrically of said annulus and is by-passed by said conductor, said screw having thereabout an insulating sleeve.

24. A transformer constructed comprising sheet-metal casing means having therein a transformer core and windings with a conductor extending from the latter, said casing means having means for mechanically connecting it to a support, said means comprising an external sheetmetal annulus projecting from said casing means,

said annulus having a peripheral flange at its outer end and both said flange and said end being subdivided into opposed relatively movable arouate portions by slit means extending lengthwise of the axis of the annulus and toward the inner end thereof whereby the resultant arcuate portions thereof are relatively displaceable in a direction toward or away from the axis of said annulus to dimensionally lessen the outer end and said flange of said annulus for passage of the flange through a round aperture of a support and to dimensionally enlarge said flange after passage through a round aperture of the support, said conductor extending through said annulus and outwardly through the outer end thereof.

25. In construction of the character described,

in combination, an outlet box having a back wall to rest against a supporting surface and side walls and having a round aperture in a side wall thereof spaced from the center of the aperture to the plane of the back Wall of the outlet box by a dis tance x, a transformer structure having a core and coacting windings and an enclosing casing therefor presenting four side faces, said casing having mounting means receivable in said round aperture, said mounting means having an axis which is parallel to said four side faces of the transformer structure and is displaced from three of said side faces by a distance greater than x and from the fourth side face by a distance less than as by an amount providing a factor of safety against fire hazard whereby said axis and the axis of said round hole in the outlet box can be brought into coincidence only when said fourth side face is toward the plane of said supporting surface, said mounting means having end portions that terminate at points on a circle that is of a diameter commensurate with the diameter of said round aperture and are thereby received in the latter when said fourth side face of the transformer structure faces toward the plane of said supporting surface, and means for securing said mounting means to said outlet box side wall with the said end portions thereof received in said round aperture and with said two axes substan tially coincident.

26. In construction of the character described, in combination, an outlet box having a round aperture in a wall thereof, a transformer structure comprising a core and windings and a casing therefor, said casing having a tubular extension communicating with the interior of said casing and having conductors extending therethrough to said windings, said tubular extension having a sub-divided end portion presenting two relatively movable clamping parts spaced substantially on a diameter commensurate with the diameter of said round aperture and receivable in said round aperture in the wall of said outlet box for substantially juxtaposing said two clamping parts within said round aperture to substantially diametrically opposite peripheral points of the latter, and means for moving one of said two clamping parts relative to the other in a substantially diametrical direction away from the other and thereby expanding the diametric spacing of said two clamping parts of said sub-divided portion of said tubular extension to clamp them against the inside periphery of said aperture.

27. In construction of the character described, in combination, an outlet box having a round aperture in a wall thereof, a transformer structure comprising a core and windings and a casing therefor, said casing having a tubular extension communicating with the interior of said casin and having conductors extending therethrough to said windings, said tubular extension having a sub-divided end portion comprising two relatively movable clamping parts spaced substantially on a diameter commensurate with the diameter of said round aperture, said extension having secured thereto adjacent said clamping parts a transverse apertured insulating plate through which said conductors extend for passage through said aperture and into said box, said two clamping parts being receivable in said round aperture in the wall of said outlet box substantially in juxtaposition to substantially diametrically opposite peripheral points of the aperture and with said transverse insulating plate positioned substantially at said aperture for insulating passage of said conductors into the outlet box, and means for moving one of said two clamping parts relative to the other in a substantially diametrical direction away from the other and thereby expanding the diametric spacing of said two clamping parts of said subdivided portion of said tubular extension to clamp them against the inside periphery of said aperture and for thereby fixing the position of said insulating plate relative to said aperture.

LEO L. VERKUIL.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,964,945 Helgason et a1. July 3, 1934 2,156,461 Rittenhouse May 2, 1939 2,246,890 Miller June 24, 1941 2,433,511 Goddard Dec. 30, 1947

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