Patent Publication Number: US-3876928-A

Title: Power transformer

Description:
United States Patent 1 Wheeler et a1.  
 [ POWER TRANSFORMER Inventors: Ernest E. Wheeler; David C.  
 Wheeler, both of 5938 Eton CT., San Diego, Calif. 92122 Filed: Sept. 30, 1974 Appl. No.: 510,449  
 Related US. Application Data Continuation of Ser. No. 382,922, July 26, 1973, abandoned.  
 US. Cl 323/43.5 R; 336/83; 336/150 Int. Cl. H011 21/12 Field of Search 336/83, 105, 150, 90, 92  
 [ Apr. 8, 1975 517.770 4/1894 Shaw 336/150 X 1,085,616 2/1914 Lennox 336/83 X 1,302,308 4/1919 Cavanagh 336/83 X 1,367,957 2/1921 Garretson 336/83 1,550,889 8/1925 Doran 336/83 X 2,179,661 11/1939 Jones 336/150 X 2,801,293 7/1957 Howell et a1 336/83 X 3,293,729 12/1966 Morrill 336/83 X Primary ExaminerThomas J. Kozma [57] ABSTRACT A power transformer having a single ferrous laminated core with primary and secondary windings surrounding the laminated core and a ferrous housing, the ends of the laminated core in abutting relationship with the side of the ferrous housing completing the magnetic path for the transformer.  
 1 Claim, 4 Drawing Figures POWER TRANSFORMER RELATED APPLICATION This application is a continuation of Ser. No. 382,922 filed July 26, 1973, now abandoned, by Ernest E. Wheeler, et al., for a POWER TRANSFORMER.  
 BRIEF DESCRIPTION OF THE INVENTION The present invention relates to a power transformer and more particularly to a power transformer enclosed in a ferrous housing for completion of a magnetic loop.  
  According to the invention, a power transformer is provided having a single laminated core in abutting relationship with a ferrous housing. The housing is preferably filled with transformer oil to a level for submerging the laminated core and the windings thereon. It has been found empirically that the magnetic circuit which surrounds the entire laminated core and windings lends a highly improved efficiency without core saturation.  
 I The particular embodiment shown has its utility as a welding transformer with a multi-tapped secondary for selecting the proper current and voltage condition dependent upon a welding application.  
  An object of the present invention is the provision of an improved power transformer.  
  Another object of the invention is the provision of a power transformer having a unique magnetic path.  
  A further object of the invention is the provision of a power transformer which is highly efficient without core saturation.  
  Yet another object of the invention is the provision of a power transformer which is extremely compact and inexpensive to manufacture.  
  Other objects and many of the attendant advantages will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing in which like reference numerals designate like parts throughout the FIGS. thereof and wherein:  
 FIG. 1 is a perspective view partially broken away of .the preferred embodiment of the present invention;  
  FIG. 2 is a partially sectioned view taken along lines 22 of FIG. 1;  
  FIG. 3 is a top view of the output switch of the embodiment of FIG. 1; and  
  FIG. 4 is a schematic representation of the embodiment of FIG. 1.  
 DETAILED DESCRIPTION OF THE DRAWING Referring to the drawings, a power transformer is shown generally at l 1 having an outside ferrous case 12 with a laminated core 13 in abutting relationship with an inside surface thereof. A plurality of windings (not shown) are carried within a plastic enclosure 14 around laminated core 13. A ferrous shelf 16 is also in abutting relationship with an inside surface of ferrous housing 12. A primary winding of transformer 11 is coupled to input terminals 17, 18, and 19. A tapped secondary winding of transformer 11 is coupled to the stationary contacts 21, 22, 23, 24, 26, 27, 28, 29, 31, 32, 33, and  
 former 11. The center arm 37 of rotary switch 36 is mechanically coupled to selector dial 42 which has a pointer 43 in proximity with calibrated top plate 44. A mechanical stop 46 is at one end of counterclockwise rotation of switch arm 37 indicating an off position. A plurality of electrical components 47, 48, and 49 are carried by ferrous shelf 16 beneath rotary switch 36. Rotary switch 36 also has a detent ring 51 for mechanically orienting rotor arm 37 on any one of the stationary contacts. Mechanical stop 46A stops the rotor at the upper limit or its extreme clockwise position which would be contact 33. A welding electrode 52 together with a workpiece 53 are shown coupled to output terminals 39 and 38, respectively (FIG. 4).  
  It can be seen by referring to the above description and FIGS. 1 and 2 that ferrous case 12 which is shown as cylindrical or circular is in abutting contact with the ends of laminated core 13 which form a magnetic circuit completely surrounding the windings of the transformer and hence lend a completely enclosed magnetic circuit. This again has been found to improve the overall efficiency of the transformer without core saturation. It is pointed out that ferrous housing 12 could be any desired geometric shape such as a square in which case the ends of laminated core 13 would be geometrically shaped to cooperate therewith in a full abutting relationship.  
  It should be understood, of course, that the foregoing disclosure relates to only a preferred embodiment of the present invention and that it is intended to cover all changes and modifications of the example of the invention herein chosen for the purposes of the disclosure which do not constitute departures from the spirit and scope of the invention.  
 The invention claimed is:  
 l. A power transformer comprising:  
 at least one ferrous core;  
 a primary winding and a secondary winding carried by said ferrous core, said secondary winding having a plurality of taps thereon;  
 a ferrous housing disposed outside of said primary winding and secondary winding, said ferrous core in abutting relationship on at least two ends thereof with said ferrous housing, said ferrous housing completely surrounding said primary winding and said secondary winding, said ferrous core being a single laminated stack, and said housing being a right circular cylinder having a closed top and bottom;  
 a rotary switch, said rotary switch having a plurality of stationary contacts each coupled to a different one of said taps and a center arm for contacting any one of said contacts, said rotary switch being disposed within said housing above said ferrous core and said primary winding and said secondary winding and sealed therefrom, said ferrous core and said primary winding and said secondary winding being immersed in oil; and  
 a plurality of electrical components disposed beneath said rotary switch and above and sealed from said primary winding and secondary winding and being sealed therefrom, each of said electrical components being connected in series with a different one of said taps.