LOUISVILLE, Ky. – Cummins has developed a training module to help people (truck writers, for instance) to better understand the technology that will be required to meet the 2007 emissions standards.

Key among the new components is the aftertreatment system consisting of a diesel particulate filter (DPF). The DPF captures soot and burns it off at high temperatures through a process called regeneration.

Regeneration can occur passively under most driving conditions, but if the DPF isn’t able to attain high enough temperatures an active regeneration may be required. In this instance, a small amount of diesel fuel is dosed into the system to increase temperatures and spark the regeneration process.

Members of the trucking trade press recently had the opportunity to witness the regeneration process first-hand thanks to a Cummins training module.

The module consists of a standalone 2007 engine and aftertreatment system. With no chassis to get in the way, a number of editors were able to gather around and enjoy an unobstructed view of the components.

The demonstration was taking place at a Cummins distributorship near Louisville, Ky. just prior to the Mid-America Trucking Show.

As service training manager Fred Murphy fired up the engine, there was no sign of the customary puff of smoke usually emitted by today’s engines upon start-up.

Exhaust temperatures must reach about 600 F for regeneration to take place, and temperature gauges on the DPF allowed us to watch the temperature climb as the engine warmed up.

While we waited, service training manager Fred Murphy described what happens during the regeneratioin process.

“We’re actively putting hydrocarbons into the exhaust stream and creating a chemical reaction to burn off the soot,” he explained.

When the exhaust gas reached about 600 F, the regeneration process began. There was no smoke and only a very subtle smell as the process took place. Cummins officials insist the driver won’t even know when a regeneration is occurring as the process is completely transparent.

Exhaust temperatures continued to climb as regeneration continued, with outlet temperatures peaking at about 903 F. During an active regeneration, only about a quart of fuel is required, according to Cummins officials.

DPF cleaning

Having witnessed a DPF regeneration, the next logical question is what becomes of the soot that was just incinerated? Jeff Weikert, executive director, midrange engineering with Cummins, explained that the soot is turned to ash, which gets picked up by a non-flow-through section of the DPF.

Eventually, this ash must be removed from the filter. While the Environmental Protection Agency requires all DPFs be able to go 150,000 miles without service, Cummins says it has far surpassed that target. Cleaning will have to be performed between 200,000 and 400,000 miles and a special DPF cleaning machine has been developed for just that purpose.

The DPF is removed from the truck and placed on the machine, which then uses a typical shop air pressure system to remove the ash. Typically, only a few grams of ash will have accumulated in the filter.

Including the removal and re-attachment of the DPF, the entire cleaning process takes about an hour and it can be carried out during a regularly-scheduled oil change.