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Cummins rolls out its new ISX

COLUMBUS, Ind. - Cummins Engine Company says it is ready for the October release of its new heavy-duty diesel engines, and expects certification of its ISX 02 engine very soon.The first limited produc...

COLUMBUS, Ind. – Cummins Engine Company says it is ready for the October release of its new heavy-duty diesel engines, and expects certification of its ISX 02 engine very soon.

The first limited production of the ISX 02 engines is awaiting shipment to Navistar International as soon as Cummins gets certification.

“Cummins will be ready for Oct. 1. Our programs are on schedule. Very soon, our ISX will be the first certified engine at October ’02 standards. Cummins is not only committed to staying in the heavy truck engine business, let me assert now, we intend to be the undisputed leader in heavy duty engines, and will do so profitably,” says Joe Loughrey, executive vice-president and president of Engine Business for Cummins Inc.

He made the comment in a press conference at Cummins headquarters in Columbus, Ind. on Mar. 18.

Loughrey says the ISX certification will also include simple and clear approval of the engine’s AECDs or auxiliary emissions control devices.

Between now and October, Cummins’ ISX 02, ISM 02, and B series engines will all be certified.

“Our C and L series engines will continue to run in today’s form, using the ‘durable credits’ we’ve earned until late 2003 when we will then go to an engine that satisfies the requirements of the (EPA, Department of Justice) consent decree,” says Loughrey.

Cummins’ immediate challenge is to adapt passenger car technology to heavy-duty diesels.

Cummins has developed technologies in-house that are critical to EGR development, says John Wall, vice-president, and chief technical officer.

This includes Cummins’ own fuel systems, turbochargers and controls.

The EGR coolers were developed in partnership with another supplier, which is currently making some 1,500 EGR coolers a day in Germany for passenger cars.

Right now, it is beginning to make larger EGR coolers for commercial applications.

“One thing that you will hear here pretty consistently through discussions about our application and emissions control technology is that the right technology matters. We need to understand what our customers are doing with their product and how to optimize our emission control solution for them,” says Wall.

“We’ve got the advantage of having the critical technology within our company so that there are no proprietary boundaries,” he says.

“We have analytical tools and the critical components in-house that allow us to develop products across the board for the application of cooled EGR.”

It is without a doubt the best fuel economy increase, but it is also a foundation for 2002 emissions and beyond – to be able to get on the order of 2.5 g NOx with this kind of fuel economy and this kind of performance really sets the stage for us to be able to take the next step toward .2 g NOx, which will take some aggressive development, he also stresses.

In developing their EGR engine over 10 years, Cummins focused on cool exhaust gas recirculation technology at 2.5 g NOx + hydrocarbons for its heavy-duty products.

“It gives us and the customer the best combination of fuel economy, performance and maintenance intervals. People don’t buy low emissions technology because it has low emissions – they buy it because it has a better value for them,” he says.

The issue is controlling peak temperature at combustion in order to control NOx.

“We looked at retarding the injection timing, where combustion happens later in the cycle, but then fuel economy gets a lot worse,” he says.

With EGR, you’re taking some of the exhaust and it acts like dead weight during the combustion process.

“When the fire goes off, you’re not only heating up the air that’s in the cylinder but you’ve got this extra mass of material that’s relatively inert. Some of the energy goes into heating that up, but since you’ve got more stuff absorbing the energy, the peak temperatures don’t get as hot, so the NOx emissions won’t be as high. So that’s one thing we’re doing with EGR,” says Wall.

According to Sam Pringle, Cummins’ executive director, Air Handling Systems, another important element of all this is that the design requirements are mutually dependent.

“You’ve got to have higher peak cylinder pressure in the engine, because you’re putting more gas in, and with this recirculated exhaust gas, you’ve got more mass in the same body, so the pressures have to be higher, and you have to have higher peak cylinder pressure, higher peak injection pressure, higher turbocharger compressor pressure, and variable control of the pressure drop across the engine, so that you can have active control of the EGR over the cycle, and heat rejection capability not just on the engine but the vehicle as well,” says Pringle.

He says Cummins has been working with the OEMs to ensure the vehicle platforms have the capacity for increased heat rejection that goes along with EGR.

In terms of the effective reliability of the total truck, and whether the peripherals such as starters, seals, hoses, and alternators will be subjected to increased heat rejection, with increases in under hood temperatures, Wall says a 200 degree temperature rise is way off.

“These are big exhaust pipes, the radiators are larger. (The trucks are) being designed to accommodate EGR,” he says.

“High heat rejection used to mean bad fuel economy. It’s the other way around now with EGR,” says Pringle.

Though Wall says Cummins is working hard on aftertreatment systems for the next round of emissions regulations in 2007, and 2010, he says that NOx aftertreatments are just not ready for prime time, i.e. for the 2002, 2004 time frame.

“That’s a technology we’re investing in and developing for the future,” he says.

“It’s just not ready for commercial applications today. But if you’re running an ISX engine today, and you substitute an ISX with cooled EGR you’ll see a three, four to five per cent fuel economy.”

Cummins says it’s continuing to work on that, by the way, as part of its optimization to reduce the fuel economy disadvantage.

“So we’re feeling like going forward from a fuel economy standpoint for most of the people that are operating equipment out there today, they won’t see a difference in fuel economy compared to the engines that they are running today, compared to an ISX with EGR,” he says.

Cummins’ EGR engines have also been designed with some hardware changes, for example a variable geometry turbocharger, (instead of fixed geometry) that will allow for active control over the pressure drop across the engine.

Fixed geometry (and wastegated) turbochargers have performance which is fixed by casting and machining geometries, while variable-geometry turbochargers (VGT’s) use a simpler swing vane design.

“With the variable geometry turbocharger, a nozzle ring is placed before the turbine wheel, through which exhaust gas flows, and if the nozzle area is varied (by moving the nozzle axially), we can change the characteristics of the turbine, and the velocity of the gas passing through,” says Pringle.

The Holset VG Turbocharger (VGT) is currently the only heavy-duty VG turbocharger in high volume production

More than 50,000 are operating in Europe, and Pringle says this technology also offers improved transient response and ‘driveability,’ with improved engine warm-up, and enhanced engine compression braking capabilities.

“In this engine you can actually close the VGT down under braking conditions, and so not only do you have the compression but turbo rides faster when you close the VGT down under braking conditions – you’re seeing about 25-30 per cent increase in braking power, particularly in mid speed range around 1,500 RPM,” says Pringle.

The trick with EGR is how well it’s executed, he says.

“We think we’re going to have the best product,” says Pringle.

By October Cummins says it will have performed 115,000 hours of lab testing.

In total, Cummins will amass 6.4 million miles of testing, both in use and on the road, by the time the manufacturer ramps up to full production of its ISX with EGR in September.

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