Acert To Be Emissions Path

Diesel Progress North American Edition, April, 2001 by Mike Osenga

New HEUI system, maybe VGT, new combustion chamber techno1ogy more powerful electronics, but no cooled EGR

It is ironic that at a time when some have come to view the diesel engine as a commodity and see little technological difference between manufacturers, that a new global engine technology battle is about to be joined.

The endgame is the Tier 3, 2007 U.S. on-road emissions regulations, which by requiring 0.2 g [NO.sub.x], 0.14 NMHC and 0.01 PM, will significantly alter the world of diesel technology. Between now and then, most of the on-highway engine manufacturers face the 2002 compliance agreement standards, essentially the early implementation of the 2004 emissions regulations, negotiated as part of the industry's settlement with the EPA. Then there are the actual 2004, Tier 2 standards, with its 2.4 g/bhp-br, NMHC [NO.sub.x] number. All of which are no easy task.

The debate between engine manufacturers over the right roads to take to reduce [NO.sub.x], PM, NMHC and all the rest to their regulated levels has just begun. And while there will undoubtedly be similar technical roads taken, there will also be differences, with each engine manufacturer seeking to differentiate itself from the others in emissions reduction technology. We're already past the opening public relations shots. Now we start getting down to specifics, which technology which engines, at what time.

In early March, Caterpillar Inc.'s truck engine group fired its salvo by announcing that beginning in the fourth quarter of 2003, all of its midrange and heavy-duty truck engines, from the model 3126 through to the C-16, will employ its ACERT (advanced combustion emissions reduction technology) system.

Saying "we'll tell you what we're going to do, but not how we're going to do it," Cat announced ACERT and in the process revealed some of what it thinks will, and will not work, in meeting the regulations facing the Peoria, Ill., manufacturer.

One popular emissions related technology Caterpillar is dismissing, is cooled exhaust gas recirculation (EGR). John Campbell, director, Truck Engine Products, said Cat would not use cooled EGR, but would not rule out the use of some other sort of EGR system. "We just don't think cooled EGR is in the best solution of our customers," he said.

What Cat did say was that its new ACERT system, which will also form the basis of its off-road emissions strategy, is made up of a number of components:

* A new, heretofore unannounced HEUI common rail fuel system -- HEUI-C as it were.

* Expanded capabilities for its ADEM electronic control package, beyond the ADEM2000 system now being used, that will include double the computing power and memory.

* What Cat labeled a "revolutionary combustion system technology."

* The probable use of variable geometry turbochargers (VGT) along with other air handling changes.

* Passive exhaust aftertreatment technologies.

A major advantage, Campbell said, is the technologies are, "cost effective to install. ACERT requires minimal new hardware, which lowers the overall cost and greatly simplifies installation for the truck manufacturer." He added that ACERT, which in many cases will use existing or new generations of current technology, will make the transition to ACERT engines "almost unnoticeable to the customer."

Further, David Semlow, marketing manager Caterpillar Truck Engine Division, said the reliability and durability of ACERT engines would be the same as existing engines. Also, horsepower ratings will likely be the same as on existing models, and changes in heat rejection will be minimal, within 2 to 3 percent, meaning existing cooling systems could be used with ACERT engines, he said.

Campbell added that the fuel economy of ACERT equipped engines is expected to be unchanged from current models, but he also dangled the intriguing possibility of a 50 percent reduction in noise with the new package. Campbell said about half of the noise reduction would come from the use of the new HEUT fuel system versus the mechanically injection system currently used, with the other half coming from structural changes to the engine itself.

Thus it seems that Cat will comply with the terms of the 2002 settlement with existing technology and banking and trading, and launch the new technology in time for the 2004 standards. Campbell said ACERT will also position Cat to meet the very, very stringent 2007 standards.

Semlow and Campbell added that ACERT engines would operate on any diesel fuels used today and that no additional service tooling will be required, with life to overhaul and oil changes at the same levels as on existing engines.

Prototype engines have not yet been placed in customer vehicles for testing, though an undetermined number of ACERT engines have been operating in trucks "under Caterpillar control."

Previewing its technology path for the 2004 diesel emissions standards and laying the groundwork for the tough 2007 regulations, Caterpillar has announced its ACERT (advanced combustion emissions reduction technology) system. ACERT will combine new electronic capabilities, with a new HEUI fuel system, possibly variable geometry turbochargers, passive aftertreatment, with a new, "revolutionary combustion system technology."