Rolls-Royce, PLC v. United Techs. Corp.

Rolls-Royce, PLC v. United Techs. Corp.

Opinion

 [***1098]  [*1327]   RADER, Circuit Judge.

In an appeal under 35 U.S.C. § 146 from a patent interference proceeding, the United States District Court for the Eastern District of Virginia held the claims of U.S. Patent No. 6,071,077 (the "'077 patent") patentable over Reissue Application No. 09/874,931 (the "'931 application"). See Rolls-Royce, PLC v. United Techs. Corp., No. 05-362, 730 F. Supp. 2d 489, 2009 U.S. Dist. LEXIS 127214 (E.D. Va. Mar. 31, 2009). Because the district court correctly determined that Rolls-Royce, PLC's ("Rolls-Royce") '077 patent would not have been obvious in light of United Technologies Corp.'s  [**2] ("UTC") '931 application, this court affirms.

The technology in Rolls-Royce's '077 patent and UTC's '931 application relates to swept fan blades used on turbofan jet engines. The fan generally consists of a cascade of fan blades that are attached to, and extend radially outward from, a central rotatable hub. The fan blades rotate around the hub to provide propulsive thrust to air entering the engine by increasing the pressure and momentum of that air. A cylindrical-shaped cover, known as a casing, encloses the fan and the rest of the engine.

Shockwaves contribute to engine noise and cause inefficiencies. This technology addresses two types of shock: endwall shock and passage shock. Endwall shock arises when pressure waves reflect off the engine casing and into the air flow. Passage shock arises from the supersonic flow of air over the fan blades. UTC's '931 application notes that the leading edge of the fan blade creates passage shock upon initial contact with the air flow. Endwall shock and passage shock bear no relation to each other and, in fact, arise in different places within the fan.

To reduce shockwaves, the prior art teaches to sweep blades either rearward or forward. A blade  [**3] bent toward the relative velocity vector is swept forward; a blade bent away from the relative velocity vector is swept rearward. The relative velocity vector is the magnitude and direction of the air flow that hits the leading edge of a fan blade. The relative velocity vector is a combination of axial and circumferential air flow. The axial air flow is the flow of air toward the engine as it engages air along its path during flight. The circumferential air flow is the flow of air in the direction of the rotation of the blades caused by the blades themselves.

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