US2804600A - Cores for electrical induction apparatus - Google Patents

Description

1957 c. G. DUENKE CORES FOR ELECTRICAL INDUCTION APPARATUS Filed Aug. 28, 1953' QLARENcE G. DU'ENKE FIG. 5.

Unite States Patent CORES FOR ELECTRICAL INDUCTION APPARATUS Clarence G. Duenke, Webster Groves, Mo., assignor to Moloney Electric Company, St. Louis, Mo., a corporation of Delaware Application August 28, 1953, Serial No. 377,093 4 Claims. (Cl. 336210) This invention relates generally to cores for electrical induction apparatus and more specifically to a core of the type having a pair of yokes between which legs are extended which contact at the opposite ends thereof with said yokes, the predominant object of the invention being to provide such a core with laminated legs, the laminations of each of which are capable of slipping slightly with respect to each other in order to avoid the necessity for providing precisely prepared faces on the opposite ends of the legs for contact with face portions on the yokes, as was the case heretofore where no slipping of the leg laminations was provided for.

Fig. 1 is a top, plan view of a core constructed in accordance with this invention.

Fig. 2 is a side elevation of the core shown in plan in Fig. 1.

Fig. 3 is a vertical section taken on line 3-3 of Fig. l, a part being shown in elevation.

Fig. 4 is a top, plan view of a modified form of the invention.

Fig. 5 is a vertical section taken on line 55 of Fig. 4.

Fig. 6 is a fragmentary section taken on line 66 of Fig. 5.

In the drawing, wherein are shown for purposes of illustration, merely, two embodiments of the invention, A designates the core shown in Figs. 1, 2 and 3. The core A comprises a pair of loops 1 and 2 which provide the core with yokes, said yokes being preferably formed from grain oriented steel, which is wound spirally to the required dimensions, and annealed and bonded, with face portions 3 ground fiat and plane. It is to be noted that there is no necessity to remove burrs caused by grinding of the face portions 3 on the yokes 1 and 2, as the laminations of the yokes are shorted only on one side, normal interlaminar resistance being maintained.

The core A includes also a plurality of legs 4 made up of grain oriented steel laminations cut to the required size and annealed and stacked. The laminations of each leg may be held together by tape material 5, wound about each leg, and the opposite ends of each leg contact, respectively, with face portions 3 of the yokes 1 and 2. The yokes and legs may be held together to provide a unitary core unit by bands 6 which embrace the two yokes 1 and 2 at the legs 4 and and whose opposite end portions are joined by suitable clips 7, said bands being drawn taut so as to make good electrical contact between the opposite ends of the legs and the face portions of the yokes.

When assembled as shown in Figs. 1, 2 and 3 with normal clamping pressure applied by bands 6, or other mechanical clamping means, a low average value of air gap is obtained at the points where the opposite ends of the legs 4 contact with the prepared face portions 3 of the yokes 1 and 2. Also, laminations of the legs 4 are so held in place in the leg structures that these laminations may slip relative to each other slightly and hence the necessity for providing six faces at the opposite ends 2,804,600 Patented Aug. 27, 1957 of the legs which are exactly perpendicular and parallel with..respect to each other is eliminated, thus making assembly of the core practical from a manufacturing standpoint.

In Figs. 4, 5, and 6 a slightly different form of the invention is illustrated. According to this form of the invention a pair of loops 8 and 8 are employed which provide the core B with yokes, these yokes being preferably formed from grain oriented steel which is wound spirally to the required dimensions and annealed and bonded, with face portions 9 ground flat and plane. Here, also, it is not necessary to remove burrs caused by grinding the face portions 9 on the yokes 8 and 8, as the laminations of the yokes are shorted only on one side with normal interlaminar resistance being maintained. The core B of Figs. 4, 5 and 6 includes a plurality of legs 10 made up of grain oriented steel laminations, cut to the required size and annealed and stacked, the opposite end faces of said legs being disposed in contact with ground face portions 9 of the yokes 8 and 8. The laminations of each of the legs 10 are held together in a manner to allow for slight movement of said laminations relative to each other by a rod and nut assembly 11, which is shown to good advantage in Fig. 5. The rod and nut assembly 11 of each leg comprises a rod 12 which is screwthreaded at its opposite ends and extends through a tube 13 formed of fiber, or other good electrical insulating material, this tube being extended through an opening 14 formed transversely through each leg and which is of considerable greater diameter than the tube 13 so as to provide an annular space 15 between the outer face of the tube and the wall of the opening 14. The rod of the rod and nut assembly of each leg has screwed on its opposite screwthreaded end portions, nuts 16 which engage against the outer faces of the outer laminations at opposite sides of the leg.

The loops 8 and 8' which provide the yokes of the core B are each disposed within a frame 17 which is of angular cross-section, as is shown to good advantage in Fig. 5, and at each leg of the core B a clamping structure 18 is provided. This clamping structure 18 comprises a U-shaped member 19 having a bridge portion 19 at its bottom, and spaced legs 19 extending upwardly from the opposite ends of said bridge portion, the yokes and legs of the core B being disposed between said spaced legs with the lower leg of lower frame 17 contacting with the bridge portion 19 of the U-shaped member of the clamping structure 18. The spaced legs of the U-shaped member 19 of the clamping structure 18 have formed therethrough adjacent to their upper ends apertures 20 through which extensions 21 of a plate 22 project, said plate 22 being extended transversely of the U-shaped member from the upper portion of one spaced leg thereof to the upper portion of the opposite spaced leg of said U-shaped member and being held in place by the projection of the extensions 21 of said plate 22 through the apertures 20 of the upper portions of the spaced legs of said U-shaped member. Also, a clamping screw 23 is provided which extends screwthreadedly through an opening formed through the plate 22 and clampingly engages the horizontal, upper leg of the upper frame 17 so as to clamp the core B between said clamping screw and the bridge portion 19* of the U-shaped member 19 of the clamping structure 18.

Thus, the laminations of the legs 10 of the core B are capable of slight slipping movement with respect to each other and hence the necessity for providing faces at the opposite ends of said legs which are exactly perpendicular and parallel with respect to each other is eliminated.

I claim:

1. A core for electrical induction apparatus comprising a plurality of parallel legs, and laminated yokes at opposite ends of the legs, each leg comprising a stack of laminations extending lengthwise of the leg, each leg having generally flat end faces, each yoke having portions wherein its laminations are generally coplanar with the laminations of the legs, said portions having flat inner faces in contact with the end faces of the legs, only said flat inner faces of the yokes being prepared to have the edges of the yoke laminations therein all flat and coplanar and lying in a plane at right angles to the length of the legs and thereby being adapted for intimate contact with the ends of the legs, insulating materialwound around each leg for holding its laminations together while permitting endwise slippage of its laminations relative to one another, and means for clamping the yokes against the end faces of the legs.

2. A core as set forth in claim 1 wherein said insulating material comprises tape wound spirally around the leg.

3. A core for electrical induction apparatus comprising a plurality of parallel legs, and laminated yokes at opposite ends of the legs, each leg comprising a stack of laminations extending lengthwise of the leg, each leg having generally flat end faces, each yoke having portions wherein its laminations are generally coplanar with the laminations of the legs, said portions having flat inner faces in contact with the end faces of the legs, only said fiat inner faces of the yokes being prepared to have the edges of the yoke laminations therein all flat and coplanar and lying in a plane at right angles to the length of the legs and thereby being adapted for intimate contact with the ends of the legs, each leg being provided with means for holding its laminations together while permitting endwise slippage of its laminations relative to one another, said means holding said laminations of each leg comprising a fastener extending transversely through the leg, and means for clamping the yokes against the end faces of the legs.

4. A core for electrical induction apparatus comprising a plurality of parallel legs, and laminated yokes at opposite ends of the legs, each leg comprising a stack of laminations extending lengthwise of the leg, each leg having generally fiat end faces, each yoke having portions wherein its laminations are generally coplanar with the laminations of the legs, said portions having flat inner faces in contact with the end faces of the legs, only said flat inner faces of the yokes being prepared to have the edges of the yoke laminations therein all flat and coplanar and lying in a plane at right angles to the length of the legs and thereby being adapted for intimate contact with the ends of the legs, each leg being provided with means for holding its laminations together while permitting endwise slippage of its laminations relative to one another, said means holding said laminations of each leg comprising a tube extending through an opening formed transversely through the leg, a fastener extending through the tube, said tube being of smaller diameter than said opening, and means for clamping the yokes against the end faces of the legs.

References Cited in the file of this patent UNITED STATES PATENTS 1,145,551 Burke July 6, 1915 1,406,246 Thordarson Feb. 14, 1922 1,834,898 Boyajian Dec. 1, 1931 2,522,244 Vienneau Sept. 12, 1950 FOREIGN PATENTS 103,750 Switzerland Mar. 1, 1924 540,662 Great Britain Oct. 24, 1941 637,142 Great Britain May 14, 1950 472,541 Italy June 23, 1952 1,040,678 France Oct. 16, 1953

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