TAMPA, Fla. – With more than 350,000 EGR-equipped engines already on the road, Cummins says it’s ready for the impending 2007 emissions standards.
Like most of its competitors, Cummins will opt for increased use of EGR to meet the new standards, coupled with a diesel particulate filter (DPF).
A crankcase ventilation system will also be used to meet the stringent new EPA emissions standards.
Cummins, which is coming off a record year for engine sales and North American earnings, says its experience with EGR makes it the right solution for 2007.
“What was right for 2002, we feel is also right for 2007,” Jim Kelly, president of the Cummins engine business and vice-president of Cummins Inc., confirmed at a press conference at the recent Technology and Maintenance Council meetings in Florida. Cummins has racked up more than 30 billion miles of experience with EGR, added Ed Pence, Cummins vice-president and general manager of heavy-duty engine business.
Cummins reps said field testing of the ’07 engines is progressing ahead of schedule.
“Field tests have been jointly conducted with OEMs and end customers,” Pence explained. “So we are able to validate performance of the entire system in real-world conditions and duty cycles. Under all conditions, performance has been impressive.”
The Cummins DPF is a key piece of the 2007 aftertreatment puzzle, and it features a diesel oxidation catalyst (DOC).
While the 2007 engines must run on ultra low-sulfur diesel (ULSD) fuel, Dr. Steve Charlton, executive director of heavy-duty engineering says concerns about poisoning the DPF with regular fuel may have been initially overstated.
“Catalysts are not poisoned … there’s no permanent effect for picking up a tankload or more of 500 PPM fuel,” he said, adding some Cummins test engines have been running on 500 PPM fuel to test its sensitivity to the sulfur. The DPF, however, will require more frequent cleaning if it’s running 500 PPM fuel. It may be a moot point, however, as Cummins officials expect 95 per cent of U.S. retail outlets will offer ULSD by October 15.
The DPF’s job is to reduce particulate matter by 90 per cent. Jeff Weikert, executive director, midrange engineering with Cummins, said the oxidation catalyst is the heart of the particulate filter.
“It allows the DPF to regenerate with passive regeneration in almost all duty cycles,” he said. That’s the key to providing equal fuel mileage to today’s engine, as active regeneration requires a shot of diesel fuel to help increase temperatures to the point where regeneration can occur.
The filter section of the DPF captures carbon and soot from the exhaust stream and holds it there until regeneration occurs. At this point, the soot is burned off at extremely high temperatures.
While Cummins officials didn’t comment on the anticipated price increase of the ’07 engines, a large chunk of the extra cost can be attributed to the DPF – and more specifically the DOC. It’s coated with costly precious metals, Weikert said.
When active regeneration is required, a dosing injector shoots diesel fuel into the system to prompt regeneration.
The DPF must must reach about 550 C to regenerate, “about the temperature a self-cleaning oven operates at,” explained Weikert.
Duty cycles that involve stop-and-go applications, light loads or extremely cold ambient temperatures may require more frequent active regeneration, Weikert said. However, he added Cummins “worked hard at maximizing the DPF’s passive regeneration capabilities.”
The driver will not notice when a regeneration is taking place, he pointed out, since there is no impact on torque, speed, noise or horsepower.
If you’re driving a 2007 tractor with Cummins power, you’ll find a DPF lamp on the dash.
If, for some reason, regeneration cannot occur during operation, this lamp will indicate that it’s necessary to perform a manual regeneration.
The driver will have to take the truck into the shop and have a mechanic trigger the regeneration process manually.
This could take 20-30 minutes and must occur within six to eight hours of receiving the warning.
“We haven’t had to use that yet in all of our field tests,” Weikert added.
The EPA requires all DPFs be able to operate for 150,000 miles before they require cleaning, but Cummins says its filters can go well beyond that target. Weikert said the Cummins DPFs can run 200,000-400,000 miles before requiring service, depending on the duty cycle.
Cummins will be making an ash cleaning machine available to fleets and shops. The DPF must be removed from the tractor and then placed in the machine, which back-flushes the filter to remove any ash accumulated inside. The cleaning machine will be available from Cummins starting in June, and will be able to clean all makes of DPFs.
Another key component to the 2007 aftertreatment system is a coalescing filter, which captures and filters crankcase emissions, then returns the oil directly to the sump.
The filters will have to be replaced every third or fourth oil change, said Weikert.
Cummins’ mid-range engines – the ISL, ISC and ISB – will be equipped with EGR systems for the first time in 2007 as well as a DPF and crankcase ventilation system, the company said.
Officials said field testing on the EGR mid-range engines has been going well.