The evolution of diesel emissions control

The development of clean diesel has been a saga of evolution punctuated by occasional milestones.

The first EPA regulations started in on-highway in the mid-1970s and that's what then drove eventual changes in off-highway engines, with the first serious off-highway regulation taking effect in 1996, according to Bharat Vedak, Vice President of Industrial Customer Engineering at Cummins Engine. His group, which includes performance, mechanical, and electronics engineers, is responsible for making sure that the products delivered to agriculture and construction customers meet those customers' expectations. He said that the current lag between on-highway regulations and their off-highway corollaries has come down to about three years.

According to Vedak, the first significant improvement to the diesel combustion process was the turbocharger, followed by charge air cooling. The next big step was electronic engine controls. While electronic governors were seen in the 1970s, Vedak cites the period of the late 1980s to early 1990s as the introduction of full authority electronics. From this brief history emerge three concepts that still drive emissions compliance. First, on-highway applications play a major role in the development of off-highway technology. Second, controlling the combustion process is critical. Third, electronics is the key that unlocks everything else.