WASHINGTON — A 78 year-old retired chemist from Georgia says he invented Caterpillar’s low emission ACERT technology for diesel engines — and for the second time, a US Patent and Trademark Office examiner agrees.

According to the New York Times, Clyde Bryant, a retired Centers for Disease Control and Prevention chemist, has been in a patent battle with the heavy-duty enginemaker over rights to the ACERT technology.

Last year, Bryant requested a “reexamination” a 2004 patent awarded to two Caterpillar engineers for the ACERT system, which injects a charge of cooled air into a diesel engine at a critical point in the combustion cycle. He claimed the patent was a restatement of a system that he patented in 2001, and the Patent Office agreed.

In the next phase, the Patent Office again sided against Caterpillar which argued that its patent should not be withdrawn and submitted statements from experts who said Bryant’s invention is too vague to have merited a patent, the Times reports.

“We are disappointed that the Examiner’s current decision is contrary to the earlier decision of the U.S. Patent and Trademark Office, which resulted in a patent granted to Caterpillar,” the company said in a statement. “Caterpillar is proud of the hard work and ingenuity of our inventors, and we will be studying in greater detail the technical reasons given for this change in position by the U.S. Patent and Trademark Office in order to determine our next steps.”

Cat has 30 days to decide whether to contest the recent declaration, which the Times states was virtually identical to the December finding. Cat can also appeal to federal court.

Cat first introduced ACERT as its solution in meeting an Environmental Protection Agency mandate to significantly reduce NOx and PM emissions from diesel engines in 2002. The move to go to ACERT was considered controversial at the time since all other major engine manufacturers elected to meet the standard with exhaust gas recirculation (EGR).

In order to meet even tougher 2007 standards, Cat stayed with ACERT but also incorporated a form of EGR, where exhaust gas is drawn from downstream of the diesel particulate filter and returned to the engine upstream of the twin turbos and aftercooler.

Last year two Caterpillar engineers, Jim Weber and Scott Leman, were named the National Inventors of the Year for 2004 by the Intellectual Property Owners Association for their work on the team that produced ACERT.

— with files from the New York Times newswire, via the Detroit News