Universal Elec. Co. v. A. O. Smith Corp.
| Decision Date | 15 April 1981 |
| Docket Number | No. 79-1342,79-1342 |
| Citation | 643 F.2d 1240 |
| Parties | UNIVERSAL ELECTRIC CO., Plaintiff-Appellant, v. A. O. SMITH CORPORATION, Defendant-Appellee. |
| Court | U.S. Court of Appeals — Sixth Circuit |
Basil C. Foussianes, William H. Francis, Barnes, Kisselle, Raisch & Choate, Detroit, Mich., for plaintiff-appellant.
Glenn O. Starke, Merl E. Sceales, Andrus, Sceales, Starke & Sawall, Milwaukee, Wis., Robert Boynton, Birmingham, Mich., for defendant-appellee.
Before LIVELY and MARTIN, Circuit Judges, and CECIL, Senior Circuit Judge.
Universal Electric Company (Universal) appeals from a judgment of the district court holding its patents 3,567,973 (973) and 3,732,616 (616) invalid. Patent 973 is a product patent and 616 is a method patent which sets forth the process by which the device in 973 is manufactured and assembled. The abstracts and specifications are identical in the two patents and the claims of 616 track some of those in 973, with added words to indicate that it is a method patent. Patent 973 was issued on March 2, 1971, and 616 was issued on May 15, 1973 as a division of 973. This action was filed by Universal on October 19, 1973, claiming infringement of both patents by A. O. Smith Corporation (Smith) and seeking an injunction, an accounting, triple damages and attorneys fees and costs. In its answer and counterclaim Smith denied infringement and sought a declaratory judgment that both of the patents in suit are invalid. The district court held both patents invalid for obviousness and held that 616 also lacks novelty. We agree with the conclusion that both are invalid for obviousness and affirm without considering the further findings of the district court with respect to infringement.
The concern of the inventors who obtained the 973 patent was to design a sheet metal casing or housing for small electric motors which would hold the components of the motor in their proper positions without the use of bolts. The inventors stated their purpose in the specification as follows:
This invention relates to electric motors and more particularly to the construction of the frame or housing of an electric motor.
In the construction of electric motors it is customary to provide a cylindrical steel sheel which encloses the stator and also to provide substantially flat circular end members or closures which support the The cylindrical shells are made by rolling a flat piece of sheet metal and welding the resulting seam together. Because of the nature of the process, it is impossible to assure that the ends of the cylinder so formed will be perpendicular to the cylindrical axis. In fact, the sheet metal may deviate as much as one sixty-fourth of an inch from a single plane thus forming a mismatch at the circumferential meeting of the ends of the sheet metal. This resulting mismatch and nonperpendicularity can only be corrected by a costly machining operation.
bearings of the motor and hold them in concentric relationship to the stator. It is customary to provide such end members with a precision machined male rabbet which nests into a female rabbet machined into the cylindrical shell, thus providing the necessary precision location of the bearing. Close tolerance is necessary to center the rotor into stator and to hold the end closures perpendicular to the shell. The end members are held in position on the shell by bolts which extend through both end members and the full length of the cylindrical shell.
There are several disadvantages to using bolts to hold the end members in place. First, because motors vary in length and because it is necessary to offer a large variety of bolt lengths for the motor for mounting purposes, an extremely large inventory of bolts must be maintained. Second, a hole must be provided in the stator for the bolt to pass through the stator. This creates an area of high reluctance to the passage of magnetic flux. This hole is also very difficult to keep free of integral insulation and varnish. Third, the bolt must be adequately insulated from the motor winding. This is done by either insulating the bolt, the winding, or by forming the winding such that there is an adequate air-gap clearance to the bolt.
Among the objects of the invention are to provide a low cost accurate means of locating and aligning the end members of an electrical motor and to secure such members to the shell of the motor in a novel manner; to provide securing means such that the process can be reversed to provide for disassembly of the motor for repairs; to have the end members secured such that there can be no relative movement to the motor shell; to provide a securing means for the end members which does not require holes, slots, or notches in the stator and does not require a special forming or insulating of either the winding or the securing means; to provide a securing means for the end members which will not require openings through either the end member or the shell which will remain open after the motor is assembled; to provide registering surfaces on the end members and shell which are not subject to distortion under impact loads.
Stated more simply, the entire purpose of 973 was to incorporate into the assembly of small electrical motors a fastening method for enclosing the ends of the cylindrical shell of the motor in a manner to prevent movement of the ends (and of components serviced by the ends), either by rotation or by displacement inward or outward. This had been accomplished previously by running "through bolts" from one end to the other. In addition to requiring a large inventory of bolts of different lengths, this method required the installation of "shimming" washers of different thicknesses in the assembly of each motor. What was sought was a way to mass produce the small motors typically used in fans and air conditioners while maintaining the efficiency and quiet operation which characterized electrical motors whose parts were secured by through bolts.
Patent 973 achieves this result by cutting notches at intervals around the end of the cylindrical housing and machining matching projections in the circular end pieces which enclose the motor. ("Circumferentially spaced" in the patent). When the end pieces are inserted into the cylinder, on a perpendicular plane to the axis of the cylinder The diagrams in attached plaintiff's exhibit 223 illustrate the operations described above. Fig. 1 shows an assembled motor, viewed from the side, with a partial cut-away to show the assembly. The cylindrical shell (16) encloses a stator (12) which is fixed and a rotor (13) on a shaft (14) which is supported by bearings (15). Fig. 2 is an end view of a motor with the circular end enclosure in place. Fig. 4 illustrates how the projections of the end pieces (22) fit into the notches (20) at the end of the cylindrical shell. Fig. 5 shows a slot in the shell (21) and the loop (23) created by the segment of the cylindrical shell which lies between the slot and the end of the shell. Fig. 6 shows how the end piece is secured against outward displacement by bending the segment inward (toward the center of the shell) and against the outer surface of the end piece.
the matching notches and projections prevent displacement inward and rotation of the end pieces. Displacement outward is prevented by a series of slots spaced at intervals around the end of the cylinder. When the end pieces are in place, the loops created by the slots are crimped or deformed downward, toward the inside of the cylinder, clamping the end pieces in place.
The specification of patent 973 requires the notches and slots to be accurately pierced in the cylindrical shell so that the distances between the base of the notches at opposite ends and the distances between the slots at opposite ends of the shell "are accurate longitudinally of the shell." When the end pieces are accurately positioned "circumferentially and axially with respect to the shells" the bearings which are supported by the end pieces will also be accurately positioned so that the longitudinal axis of the rotor will "coincide with the longitudinal axis of the shell." In other words, the rotor and shaft will lie squarely in the longitudinal axis of the cylindrical housing. To achieve this result the end pieces must be secured in a position which is perpendicular to the cylindrical shell.
It was stipulated that claims 1, 2, 3, 12, 13 and 17 through 24 of patent 973 were claimed to be infringed. Claims 1-3, 12 and 13 describe "an electric motor" combining the features described above and claims 17 through 24 describe "a dynamo-electric machine" incorporating the same basic features. The purpose of each embodiment of the claimed invention is the same and this purpose is achieved basically in the same manner in each. All claims refer to a means of securing the "end members" or "end frames" of an electric motor housing in such a manner as to prevent their rotation or displacement. The accused device of Smith incorporates notches and projections, together with slot-loops, to accomplish the same result as shown in attached exhibit 1, which pictures an assembled A. O. Smith motor.
NOTE: OPINION CONTAINS TABLE OR OTHER DATA THAT IS NOT VIEWABLE
For our purposes the only significant difference between the motor housings is that Smith uses self-aligning bearings, which require less accuracy in fabrication than those used by Universal.
The patent examiner cited three prior art references. All related to electric motors. In support of its claim of invalidity, Smith cited a number of patents relating both to electric motors and to other mechanisms where cylinder ends were held in place by notches and projections,...
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