US 873253 A
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No. 873,253. PATENTED DEC. V10, 1907.
COIL FOR ELECTRICAL APPARATUS. APPLIGATION FILED 00118, 1905.
yWITNESSES: INV NTOR Z QJ a@ ATTORNEY PAUL MACGAHAN, OF PITTSBURG, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC MANUFACTURING COMPANY, A
CORPORATION OF PENNSYLVANIA.
COIL FOR ELECTRICAL APPARATUS.
Specification of Letters Patent.-
Patented Dec. 10, 1907.
Application filed October 18, 1905. Serial No. 283\338.
My inventlon relates to electrical apparatus and, particularly to helical coils for such apparatus.
he object of my invention is to provide a helical coil of'a small number ofturns which shall exert a uniform, magnetic pull.
In the operation of a solenoid, as ordinarily constructed7 that comprises only one or but a few convolutions of a large conductor it has been found that a non-uniform magnetic field is roduced in the interior space occu ied by t e core, the denser'portions of the eld being produced in proximity to the sides of the lsolenoid where the larger number of conductors occur. For instance, in a solenoid having but a single convolution the denser portion of the field occurs near the side where theconductor crosses ,itself at the beginning and ending of the convolution, f If a magnetizable core movable longitudinally in the interiorspace it will be drawn to one side so as to operate in the denser portion of the field. This displacement from an vaxial position is objectionable in many devices, such, for example, as measuring instruments. .f A solenoidfconstructed inaccordance with my invention comprises a plurality of inter-I v leaved and symmetricajly disposed helices the corresponding ends, of which are uniformly spaced apart and connected to suitable ring-shaped terminal pieces. Thenumber of conductors adjacent all sides of the opening is substantially the same and the field, consequently, is uniform.
My invention permits of the construction of solenoids having less than a single convolution'or any full or fractional numbers of convolutions which will produce substantiallyuniform fields throughout their interior spaces.
Figure 1 of the accom anying drawing is l a front elevation of an e ectrical measuring instrument having a coil that embodies m f invention. Fig. 2 is a plan view of the coil v shown in Fig. 1 and Fig. 3 is a side elevation of one section of the coil shown in Figs. '1 and 2.y
in the county of Allegheny and" The casing 1 of the instrument may have a suitable back or base plate 2 upon which are supported the operating parts of the instrument, these parts comprising a solenoid 3, a core 4, a liexible support 5 for the core, a segmental block 6 to which the flexible support 5 is connected 'and with the curved face of which it engages, an ad`ustable counter weight 7 for the block 6 an a pointer 8, the free end of which moves over a suitable scale 9. The parts just referred to may be of any well known construction except the solenoid 3, the novel, structural features of which constitute my present invention. The coil 3, instead kof being composed of a single continuous helix, as is usual, comprises a plurality of helices 10, 11` .and 12 that are mterleaved y and symmetrically .disposed and the ends of which are .uniformly spaced apart and .connected to suitable conducting Vrings 13 and 14.
While I have here shown the compound helix as composed of three constituent helices may be greater or less than three if desired, it being essential, however, 1n order to secure thoughout the area of the opening in the solenoid, to uniformly space t e constituent iortions', and obviously the greater. the number of members iemployed' the closer will be the ap roximation to uniformity in the magnetic field.
I claim as my invention: 1. A solenoid comprising a plurality of in'- terleaved single layer helices of substantially 4equal diameter and-length and connected-in parallel relation. f
2. A solenoid comprising a plurality of interleaved, equally spaced helices of equal lengthI and conducting rings connecting corresponding ends together.
l3. An actuating coil for electrical measuring instruments comprising a plurality of interleaved, helices ofthe same diameter and separated throughout by air spaces and means for electrically connecting corresponding ends together.
4. A multiple solenoid comprising a plurality of helical strap coils symmetrically disposed and separated from each other by uniform air spaces, and means for connectlng corres onding ends together.
5. n solenoid comprising a plurality of interleaved helices uniformly separated from I desire it to be understood that the number substantial uniformity of the `magnetic'ield each other by air spaces and connected in In testimony whereof,A l llave hereunto parallelrelation. subscribed my name this 13th day of Octo- 6. A solenoid comprising a plurality of inber, 1905. terleaved and symmetrically disposed helices PAUL MACGAHAN 5 the corresponding ends of which are spaced Wvitnesses:
apart and connected to suitable ring-shaped I S. M. TRUXAL,
terminal nieces. i BIRNEY HINEs.