Clarage Fan Co. v. B. F. Sturtevant Co.

148 F.2d 786, 65 U.S.P.Q. (BNA) 203, 1945 U.S. App. LEXIS 4508
CourtCourt of Appeals for the Sixth Circuit
DecidedApril 4, 1945
DocketNo. 9757
StatusPublished
Cited by6 cases

This text of 148 F.2d 786 (Clarage Fan Co. v. B. F. Sturtevant 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
Clarage Fan Co. v. B. F. Sturtevant Co., 148 F.2d 786, 65 U.S.P.Q. (BNA) 203, 1945 U.S. App. LEXIS 4508 (6th Cir. 1945).

Opinion

FUCKS, Circuit Judge.

Suit by B. F. Sturtevant Company (herein called Sturtevant or appellee) against Clarage Fan Company (herein called Clarage or appellant) for infringement of patent No. 1,846,863 (herein called No. 863), for “Fan and Method of Operating the same” issued to Hagen, February 23, 1932, and for infringement of patent No. 1,989,413 (herein called No. 413) issued to Hagen, January 29, 1935, for a “Centrifugal Fan.”

In an amended complaint Sturtevant based its suit on claim 2 of No. 863 and the four claims of No. 413 and sought to hold Clarage bound from contesting these claims because of a decree of validity and infringement thereof by the Circuit Court of Appeals for the First Circuit in B. F. Sturtevant v. Mass. Hair & Felt Co., 1 Cir., 122 F.2d 900, and 1 Cir., 124 F.2d 95.

The chief defenses to the original complaint were invalidity, anticipation and non-infringement, and to the amended complaint that Clarage’s Exhibits B and C charged to infringe were not substantially identical with the apparatus held to infringe in the First Circuit case, herein called the Massachusetts case, and in evidence in this case as Sturtevant’s Exhibit 3, and that the claims were so limited in the Massachusetts case as not to cover the apparatus illustrated in Exhibit B.

The District Court held that the validity of the patents in suit and their infringement by Exhibit 3 was res adjudícala; and adjudged that claim 2 of No. 863 and claims 1 to 4 inclusive of Nó. 413 were infringed by said Exhibit 3 and by Clarage’s Exhibits B and C which represented only slight modifications of the apparatus (identical with Exhibit 3) held to infringe in the Massachusetts case.

In the Massachusetts case the Master and Court both found No. 863 valid and infringed as to claim 2 and invalid as to claim 1 and No. 413 invalid. The Court of Appeals upheld the holding as to No. 863 but reversed the decree as to No. 413 and adjudged the four claims thereof to be valid and infringed. Following the decree of the Court of Appeals, Sturtevant disclaimed claim 1 of No. 863 and that claim is not involved here. All claims in suit are for apparatus.

Patent No. 863 calls for “a fan and method in which the power may be varied at constant speed while maintaining a high efficiency.”

Patent No. 413, a refinement of No. 863, calls for a centrifugal fan “in which the fluid may be admitted directly from the atmosphere and which has provision for imparting a controllable spin velocity to regulate the output of the fan.”

In systems, in which fans either forced or pulled air through passageways, it was often desirable to vary the air pressure. [788]*788This had been achieved in the past by the use of controls or dampers within the passageways themselves, but this involved wastage because the fans would continue to develop maximum pressures.

Another system used a variable speed motor and was efficient only if the motor operated on direct current or if a steam turbine was used to drive the fan. But where an alternating current was used, pressure control required auxiliary electrical control apparatus to change the speed of the motor, and a motor so equipped was costly and inefficient.

The Hagen patents, however, utilized a third principle, called spin control. The principle of spin control was very old and in the Massachusetts case, claim 1 of No. 863, a method claim (not in'issue here), embodying an extension of the principle to a commercial situation, was held invalid for anticipation.

The Hagen patents used a constant speed motor in connection with a fan having an arrangement of vanes at its inlet which could be adjusted to impart a spinning motion to the entering air in such manner that the pressure of the air in the system could be varied to meet shifting needs. As the vanes were adjusted to vary the spin of the air, the power input of the motor also varied, even though it continued to run at constant speed. (By analogy, a boy pulling a wagon at constant speed, exerts more energy on a hill than on level ground.) The savings in power by motor and fan assemblies using vane control were appreciable and undisputed.

PATENT No. 863.

This patent revealed an induced draft fan with a scroll-shaped inlet at each side of the impeller, around which was arranged a circular collar of curved, movable vanes which overlapped in closed position and were mounted parallel to the axis of the fan. In the wide open position of the blades the air tended to enter the eye of the fan largely in a radial and axial direction. In that position the operation was similar to that of the ordinary centrifugal fan, and the maximum force was exerted by its blades on the air. It was the position used when the maximum demand for air volume was placed on the fan. As the vanes were moved from the open toward the closed position, they imparted an increasing spin velocity to the air, which tended to approach the linear velocity of the blades themselves and reduced the work done by them and by the motor. If the spin velocity equalled the linear velocity, the work done by the fan would be zero. However, even to approach such identity of velocities would require careful machining and adjustment of the fan blades, and such nicety was not demanded by industry. Hagen’s testimony was that, if by spin control, the action of the fan was reduced to 30% of its capacity, that minimum would be commercially acceptable.

The specification of No. 863 states that when the vanes are completely closed, they overlap in such a way as to form a practically continuous surface — ■

“In other words, the fluid directing surfaces of two adjacent vanes overlap in closed position and are substantially parallel for all other positions, that is, they are as nearly parallel as they can be made having regard for the angular displacement of the vanes about the periphery of the eye. As the vanes close, the fluid directing surfaces come into closer parallelism until when completely closed, they form a complete ring about the eye of the fan. The practical parallelism of the surfaces of adjacent vanes forms between them a fluid directing throat of substantially uniform cross-sectional area, which assures the entrance of fluid into the fan with the proper and definite angle approaching tangential admission as the vanes are closed.”

Claim 2 follows, to wit:

“The combination with a constant speed motor, of a centrifugal fan having a rotor, an inlet, a plurality of vanes in the inlet forming fluid directing passages to admit fluid to the rotor with a spin component of velocity in the direction of rotation of the rotor, the vanes being adjustable to vary the output of the fan through a range from maximum capacity with the vanes open to a minimum capacity with a substantially tangential admission of fluid when the vanes are closed, adjacent vane surfaces continuously approaching parallelism and hazing extended overlapping portions shaped to define passages of substantially uniform cross-section as the vanes are moved toward closed position." (Italics ours.)

Exhibit 3, held to infringe in the Massachusetts case, was a forced draft fan with a necessarily different arrangement of vanes. There was no scroll at the end of a series of ducts as in No. 863, but conical [789]

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148 F.2d 786, 65 U.S.P.Q. (BNA) 203, 1945 U.S. App. LEXIS 4508, Counsel Stack Legal Research, https://law.counselstack.com/opinion/clarage-fan-co-v-b-f-sturtevant-co-ca6-1945.