Alcor Aviation, Inc. v. Radair, Inc.

• Decision Date: 10 September 1975
• Docket Number: No. 72--2708,72--2708
• Citation: 527 F.2d 113
• Parties: ALCOR AVIATION, INC., Plaintiff-Appellant, v. RADAIR INCORPORATED, a corporation, Successor to Radair, Inc., and Uniwest, Inc., Defendant-Appellee.
• Court: U.S. Court of Appeals — Ninth Circuit

Page 113

527 F.2d 113

188 U.S.P.Q. 549

ALCOR AVIATION, INC., Plaintiff-Appellant, v. RADAIR INCORPORATED, a corporation, Successor to Radair Inc., and Uniwest, Inc., Defendant-Appellee.

No. 72--2708.

United States Court of Appeals Ninth Circuit.

Sept. 10, 1975.

As Amended on Denial of Rehearing and Rehearing

En Banc Feb. 2, 1976.

Edward B. Gregg (argued), San Francisco, Cal., for plaintiff-appellant.

Benjamin F. Berry (argued), Seattle, Wash., for defendant-appellee.

OPINION

Before WRIGHT and WALLACE, Circuit Judges, and LYDICK, ^* District Judge.

WALLACE, Circuit Judge:

Alcor Aviation, Inc. (Alcor) is the assignee of Patent No. 3,154,060, filed in 1962 and granted in 1964, which relates to an apparatus and method for manually setting the fuel-air mixture of internal combustion gasoline engines by reference to exhaust gas temperature. Alcor sued Radair Incorporated (Radair) for infringement and infringement was admitted if the patent was valid. The district court held all six claims under the patent invalid for obviousness, 35 U.S.C. § 103, and lack of novelty, 35 U.S.C. § 102(a), (b). Alcor appeals only the ruling on the validity of claim 6, which relates to a method of controlling the fuel-air mixture of an engine on a flying aircraft. ¹ Alcor has disclaimed apparatus claims 1 and 2, as well as method claims 3, 4 and 5. We affirm the district court's holding that claim 6 lacked inventiveness because it would have been obvious to one having ordinary skill in the pertinent art. ² Thus we need not consider other grounds also used by the district court upon which the patent was found to be invalid.

Gasoline piston engines ignite a mixture of air and gasoline for combustion and proper performance depends upon a correct ratio of gas to air. Because the conditions of combustion vary as an aircraft increases or decreases speed and altitude, the proper mixture setting changes during flight. Although some general aviation planes have automatic devices which control mixture, most have a control by which pilots can manually readjust the mixture setting when a plane changes altitude or speed. Methods to determine the proper mixture control setting include: leaning to roughness, leaning to maximum power (as measured by rpm), leaning by reference to a fuel flow indicator, leaning by reference to the color of the exhaust flame, leaning by reference to a device which analyzes the exhaust gases and leaning by reference to the torque of the engine shaft measured by the brake mean effective pressure. Alcor's patented method of setting the fuel mixture is by reference to the engine exhaust gas temperature (EGT). The method was marketed in conjunction with unpatentable EGT measuring devices and the package was a great commercial success. It is now the most popular mixture control method for general aviation aircraft.

The scientific basis of Alcor's method is that an engine runs hottest when the ratio of fuel to air is such that all of the mixture is burned, leaving no excess of air or fuel. This occurs at a fuel-air ratio of .067, called the 'stoichiometric ratio.' A rich mixture, more fuel to air than in the stoichiometric ratio, will give greater power; and a slightly lean mixture, less fuel to air than in the stoichiometric ratio, will give greater economy. Either a rich or lean mixture will cause the engine to run cooler, which minimizes mechanical problems associated with hot engines. The EGT of the engine can be measured by a probe in the exhaust which the pilot reads on a meter in the cockpit. The patented method of mixture control is quite simple: as a plane flies at a constant speed and altitude, the pilot merely varies the manual mixture control until the maximum EGT is reached; the mixture is then either leaned or enriched to produce an EGT having a predetermined relation to peak EGT.

The first question is whether the district court properly rejected the statutory presumption of validity of the patent. 35 U.S.C. § 282. A presumption of non-obviousness dissipates upon a showing that the prior art was not brought to the attention of the patent examiner. Hewlett-Packard Co. v. Tel-Design, Inc., 460 F.2d 625, 628 (9th Cir. 1972); Jacuzzi Bros. v. Berkeley Pump Co., 191 F.2d 632, 634 (9th Cir. 1951). The district court made findings as to what the prior art included. Those findings are not clearly erroneous. None of the cited examples of prior art was considered by the examiner. For instance, the 1941 Minter patent, No. 1,251,751, is a device for controlling the fuel-air mixture in airplanes. The district court found that the Minter patent not only discloses the basic relationship between fuel-air ratio and engine exhaust gas temperature, it also teaches a method of using this relationship for automatically controlling fuel mixture by use of a temperature probe in the exhaust gas stream.

Absent the presumption, the next question is whether the district court erred in determining obviousness. Whether the subject matter of a patent was obvious is decided by considering the scope and content of the prior art, the differences between the prior art and the disputed claim, and the level of ordinary skill in the pertinent art. Graham v. John Deere Co., 383 U.S. 1, 17, 86 S.Ct. 684, 15 L.Ed.2d 545 (1966); Walker v. General Motors Corp., 362 F.2d 56, 59 (9th Cir. 1966). The district court correctly determined that the art of internal combustion engine thermodynamics was the art pertinent to Alcor's patent. Alcor admits that the probes and meters were used in the prior art to measure EGT. It was also textbook knowledge that EGT varies with the fuel-air ratio and peaks at the stoichiometric ratio. In addition, it was known that best power or best economy is achieved by a mixture setting either richer or leaner than the stoichiometric ratio, as represented by peak EGT. Although Alcor's patent does not mention specific relationships, even the exact EGT drop for many engines was known in the prior art, readily available in pilot manuals and test studies.

Moreover, these EGT devices and theories were utilized together in the prior art. EGT probes and indicators were used in testing new airplane engines, both on the ground and in the air. Examples discussed during the trial included the Curtiss-Wright test stand practices in the 1940's and the Lockheed Constellation and Douglas DC--7 in-flight tests in the early 1950's. Under constant conditions the fuel-air mixture was varied and all changes in engine performance noted, including such variables as cylinder head temperature, power (as measured by brake mean effective pressure), fuel consumption and, of course, exhaust gas temperature. Indeed, it was from these tests...