Board of Patent Appeals and Interferences Rules on Indefiniteness of the Term “Substantially Filled,” Prima Facie Obviousness in an Engine Cooling Method

By Charles Pierce

In Ex Parte Evans et al. (Appeal 2011-004119; Application serial no. 11/823,993), the Board of Patent Appeals and Interferences reversed examiner rejections under 35 U.S.C. § 112 for indefiniteness, and 35 U.S.C. § 103(a) for obviousness.

Claim 1 of the patent states:

A method for cooling an internal combustion engine using a reduced toxicity, ethylene glycol and water based heat transfer fluid, said method comprising the steps of:

(a) formulating a heat transfer fluid comprising (1) a glycol component consisting of ethylene glycol and propylene glycol, wherein the weight of the propylene glycol is between 5% less to less than 30% of the total weight of the glycol component and wherein the glycol component is less toxic than 10,000 mg/kg on an acute LD50(rat) oral toxicity basis, and (2) water, wherein the water comprises between 40% and 70% by weight of the total weight of the heat transfer fluid; and

(b) substantially filling the cooling system of the internal combustion engine with the heat transfer fluid such that the heat transfer fluid absorbs heat that is produced by the internal combustion engine and releases the absorbed heat to the atmosphere. (emphasis added).

The examiner rejected this claim reasoning that because the term “substantially” is not defined, the specification does not sufficiently describe the invention such that a person of ordinary skill in the art would be reasonably apprised of its scope.  The board disagreed.  They noted that “substantially” was used to describe how much a cooling system should be filled, and any person skilled in the art would know what can be considered substantially filled.  The term “substantially” was used to avoid a strict measurement,  because slight variations in the amount of fluid may still be considered to have filled a cooling system.  The board decided that the claim was sufficiently definite.

The board also disagreed with the examiner’s obviousness rejections.  The examiner’s rejection was that the claims were prima facie obvious.  The board noted that no reference disclosed the weight range of the propylene glycol in the glycerol component, or the weight range of the glycerol in the polyhydric alcohol component.  Because the references also disclosed only the components of the invention, the board ruled that they were not enough for a person of ordinary skill in the art to create the claimed cooling method.

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