Eaton Corp.’s Internal Exhaust Gas Recirculation (iEGR) technology enables automakers to meet stringent regulations on diesel engine emissions by providing direct control over the thermal management of the exhaust system. The iEGR technology also provides superior cold start characteristics over hydraulic solutions, whatever the engine condition.
How It Works
Diesel exhaust leaves the engine following combustion with pollutants nitrogen oxides (NOx) and particulate matter (PM), which includes soot particles primarily made up of carbon, ash, metallic abrasion particles, sulfates, and silicates.
The particulate matter is trapped in a diesel particulate filter (DPF) and diesel exhaust fluid is sprayed into the exhaust, where it hydrolyzes into an ammonia gas (NH3).
From there, the ammonia and nitrogen oxides travel to a selective catalytic reduction (SCR) system where a reaction turns them into harmless nitrogen and water. In order for the reaction to occur, however, temperatures of 250–500°C are needed.
iEGR is used to generate hotter exhaust gas, and therefore heat the catalyst to the proper operating temperature, by slightly opening one exhaust valve during the piston’s intake stroke to draw hot exhaust gas directly from the exhaust manifold into the cylinder.
Unlike competitive systems, Eaton’s iEGR technology uses a switchable roller rocker arm on each cylinder that can be electromechanically actuated. Systems that rely on hydraulic pressure to provide iEGR functionality take longer to generate heat, whereas Eaton’s system provides the needed heat nearly instantaneously, helping to eliminate harmful emissions during cold starts.
Some competitor systems can generate instant heat, including those that use electric heaters, more complex after-treatment systems, or bigger NOx traps. However, those solutions add weight, complexity, and cost.
Conversely, valvetrain solutions such as Eaton’s iEGR system require little space and utilize existing engine heat to increase temperature output.
Eaton’s latest generation of switchable roller rocker arm also features significant improvements regarding friction. Instead of using a high friction sliding pad on either the main or secondary valve-lift event, Eaton uses lower friction rollers to improve the overall engine efficiency.
Edited by Motorized Vehicle Yearbook Editor Bill Koenig from Information supplied by Eaton Corp.