Home/Sixth Circuit/General Electric Co. v. Bullock Electric Mfg. Co.

General Electric Co. v. Bullock Electric Mfg. Co.

152 F. 427, 81 C.C.A. 569, 1907 U.S. App. LEXIS 4299
CourtCourt of Appeals for the Sixth Circuit
DecidedMarch 21, 1907
DocketNo. 1,566
StatusPublished
Cited by4 cases

This text of 152 F. 427 (General Electric Co. v. Bullock Electric Mfg. Co.) is published on Counsel Stack Legal Research, covering Court of Appeals for the Sixth Circuit primary law. Counsel Stack provides free access to over 12 million legal documents including statutes, case law, regulations, and constitutions.

Bluebook
General Electric Co. v. Bullock Electric Mfg. Co., 152 F. 427, 81 C.C.A. 569, 1907 U.S. App. LEXIS 4299 (6th Cir. 1907).

Opinion

RICHARDS, Circuit Judge.

This was a suit in equity brought by the General Electric Company against the Bullock Electric Manufacturing Company and others, for an injunction, with the usual prayer for an accounting, for the infringement of claim 1 of letters patent No. 463,704, issued November 24, 1891, to Albert H. Par-celle, the assignor of the complainant, for improvements in an electric motor and dynamo. The answer set up want of novelty and invention and denied infringement. The court below in a short opinion held -that patentable invention was not shown and dismissed the bill. From .this decree an appeal has been taken.

.The Parcelle invention in suit relates to the field magnet of a dynamo and provides a method of firmly fastening the laminated pole piece to the solid yoke thereof. A dynamo consists of two parts, the field magnet and the armature; the one being rotated and the other stationary. In the stationary field machine ■ the armature is rotated within- the field magnet, while in the revolving one the field magnet is rotated within the armature. The field magnet consists of a yoke and pole pieces, the number of the latter varying, but being alternately north and south; the magnetic lines of force being projected from the tip of one pole through the armature core back into the tip of the adjacent and opposite pole, and thence through the yoke to the first pole. As the conductors on the surface of the armature move through these lines of force, a current of electricity i's generated. The armature is, of course, not in contact with the pole pieces of the field magnet, since the latter must rotate within the former, or the reverse, in order to generate electric energy. Yet at the same time the air gap which separates the two must be kept very small, in some cases not wider than one-eighth of an inch, in order not to interfere with the magnetic circuit. This intimate proximity of the pole pieces to the armature riecéssarily calls for careful and precise construction and adjustment of the former with respect to the latter. Early in the history of the art, as early as 1879, it was found to be desirable to use toothed arma[429]*429ture cores, and it was then ascertained that, in order to avoid Foucault or Eddy currents in the field magnet pole pieces, it was necessary to laminate the latter. This necessity, however, did 'not extend to the yoke of the field magnet. It was cheaper and equally effective to keep it of solid iron. The problem, then, was to fasten the laminated pole piece firmly and rigidly to the solid iron yoke, so as to subserve all magnetic and electric requirements, resist all centrifugal and magnetic strains, permit the ready removal of the pole piece sidewise for repairs, and secure and preserve an expanded tip. .

The court below, in its opinion, sought to limit the requirements of the problem solved by Parcelle to those of a purely mechanical nature. True, there was a mechanical problem, the firm fastening of the laminated pole piece to the iron yoke; but it was complicated by certain magnetic and electric conditions. These conditions brought about the necessity of the laminated pole piece, and the mechanical problem of fastening it to the yoke was varied by the magnetic and electric -requirements to be subserved. The pole piece had to be laminated, yet each laminae had to be clamped to the yoke so as to make a good magnetic joint. It was desirable to make the pole piece removable, in order to be able to use an expanded pole tip; and the side pieces could not in all cases be made thick enough to receive the bolts to hold the pole piece to the yoke without interfering with the magnetic and electric requirements of the problem. Before the necessity of laminating the pole pieces was known, solid pole pieces were attached to the yoke by bolts or screws. These pole pieces were readily removable sidewise. But with laminated pole pieces it became impracticable to do this, although the Dresskell patent, granted January 27, 1891, shows a method of tapping a bolt directly into the laminated plates; but this was a defective method, because of the fragile nature of the laminae.

Prior to the invention in suit, either the pole pieces were made integral with the yoke, and both laminated, as shown in the Jablochkoff, Zipernowsky, Schmidt, and other patents, or by casting the yoke around the laminated pole pieces, as in the, Schmidt patent of December, 1889, or by bolting the side plates of the pole piece to the core, they being thickened for that purpose, as in the Storey patent of 1890. None of these methods of fastening the pole piece to the yoke was esteemed successful. Laminating both the pole piece and the yoke was expensive, and the pole piece was integral with the yoke. The pole piece could not always be cast firmly within the yoke, and, besides, was irremovable; and to place the bolts in the side plates made them too thick and interfered with the preservation of the proper magnetic and electric conditions. Parcelle solved the mechanical problem of detachably fastening the laminated pole' piece to the solid yoke by anchoring into the laminated plates a supporting bar, into which the bolts which held the pole piece to the yoke were firmly screwed. We insert here figures 1 and 3 of the Parcelle patent, which, taken in connection with the appropriate extract from the specification, which follows, sufficiently explains the patented structure:

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Cite This Page — Counsel Stack

Bluebook (online)
152 F. 427, 81 C.C.A. 569, 1907 U.S. App. LEXIS 4299, Counsel Stack Legal Research, https://law.counselstack.com/opinion/general-electric-co-v-bullock-electric-mfg-co-ca6-1907.