In a previous post, I discussed the infringement suit in which Kruse Technology Partnership (“Kruse”) accused several automakers, including Daimler, Mercedes-Benz USA, Volkswagen, Ford and Chrysler of infringing U.S. Patent Nos. 5,265,562 (“’562 patent”), 6,058,904 (“’904 patent”) and 6,405,704 (“’704 patent”) relating to higher efficiency and lower emission diesel engines.
The asserted patents are entitled “Internal combustion engine with limited temperature cycle” and directed to Kruse’s “Limited Temperature Cycle” technology, which limits peak combustion temperatures in direct injection gas and diesel engines.
The Court of Appeals for the Federal Circuit recently affirmed a district court grant of summary judgment of non-infringement of the ’562 and ’904 Patents in favor of Volkswagen.
According to the ’562 and ’904 Patents, fuel is injected in first and second fractions at different points in the operating cycle of the engine, resulting in a combustion process having “a constant volume (isochoric) phase and a constant temperature (isothermal) phase.”
The asserted claims recite “the combustion as a result of the introduction of the second fraction is a substantially isothermal process,” which was construed by the district court to require that the average cylinder temperature “remains substantially constant from the beginning until the end of the combustion.”
On appeal Kruse first argued this interpretation was incorrect and unduly narrow, but the Federal Circuit disagreed and said the district court’s construction is the “only permissible reading” of the term:
The only permissible reading of the limitation “the combustion . . . is a substantially isothermal process,” is that it requires a substantially constant temperature for the entire second fraction combustion. . . . [T]he combustion . . . is a substantially isothermal process,” does not indicate that only a portion of the combustion is isothermal.
Kruse also contended that the district court erred in holding that isothermal combustion of 23% – 48% of the second fraction in the Volkswagen products was not an infringing equivalent element of the claimed “substantially isothermal process” limitation. Specifically, Kruse argued that the difference in combustion is insubstantial and one of degree.
The Federal Circuit disagreed. While some deparature from the entirety of the second fraction combustion might be permissible, the court held that a 23% – 48% duration cannot be equivalent to combustion over the full duration of the fraction:
While the claim limitation, as construed, by no means precludes some departure from the entirety of the second fraction combustion, we find no error in the district court’s conclusion that the claim term is not flexible enough to allow the 23% to 48% duration of the second fraction combustion. Allowing such a percentage to be equivalent to combustion over the full duration is contrary to the meaning of the claim limitation and would render it meaningless. Isothermal combustion for less than half of the second fraction combustion cannot logically be considered insubstantially different from combustion from beginning to end; and . . . no reasonable juror could find otherwise.
Eric Lane is a patent attorney at McKenna Long & Aldridge LLP in San Diego and the author of Green Patent Blog. Mr. Lane can be reached at elane@mckennalong.com
