Cummins Engine Company says its programs are on schedule for the October 1 release of its new heavy-duty diesel engines, and expects certification of its ISX 02 engine very soon.Cummins has developed ...
Cummins Engine Company says its programs are on schedule for the October 1 release of its new heavy-duty diesel engines, and expects certification of its ISX 02 engine very soon.
Cummins has developed technologies in-house that are critical to EGR development, said John Wall, Vice President, and Chief Technical Officer.
“We have analytical tools and the critical components in-house to develop products across the board for the application of cooled EGR,” he said.
The key issue with EGR technology is controlling peak temperature at combustion in order to control NOx.
“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,” said Wall.
“Another important element of all this is that the design requirements are mutually dependent: higher peak cylinder pressure in the engine, 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,” said Sam Pringle, Cummins’ Executive Director, Air Handling Systems.
He says Cummins has been working closely with the OEMs to ensure that the vehicle platforms have the capacity for increased heat rejection that goes along with EGR.
“If you’re running an ISX engine today, and you substitute an ISX with cooled EGR you’ll see a three, four to five percent fuel economy. We’re continuing to work on that as part of our 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,” said Wall.
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.
“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. The VGT is there primarily to generate EGR under different operating conditions. However, it does give you additional benefits in low-speed torque,” said Pringle.
He says the VGT also offers improved transient response and ‘driveability’, with improved engine warm-up, and enhanced engine compression braking capabilities.
“Drivers will hear something different as the exhaust pressure drops and the turbo speed drops and so drivers will be able to hear the turbo which tends to be in sync with the rest of the engine. It’s not quite completely mutually exclusive now-drivers will hear something aside from what they are used to hearing,” said Pringle.
By October Cummins says they will have performed 115,000 hours of lab testing, with 30 vehicles set aside for the ISX field test alone. In total Cummins will amass 6.4 million miles of testing in use and on the road, in vehicles, by the time they ramp up to full production of their ISX with EGR in September.