Exhaust Gas Recirculation (EGR) is an emission control strategy that offers significant reduction in NOX emissions from internal combustion engines. EGR was applied in light-duty gasoline and diesel-fueled vehicles in the mid-1970s and has transferred over to heavy-duty diesel engines from the early 2000s.
As of the 2008 model year, Yanmar has implemented EGR technology as part of its strategy for engines above 56 kW (75 hp) to meet the Tier 3 and Stage IIIA emissions regulations.
EGR is a method by which a portion of the engine’s exhaust gas is reintroduced to the combustion chamber through the intake system. The primary of effect of EGR, reduction of NOX, is created by reduction in combustion temperatures. Reduction of NOX does come with an increase to other exhaust constituents: PM, HC and CO emissions. However, Yanmar has taken the effort to implement additional engine modifications: electronically-controlled fuel injection, combustion and fuel injection optimization. Yanmar’s efforts also minimize the impact EGR would normally have on fuel economy and power density in order to provide you the same platform for all applications and ensuring compliance to the most stringent emissions regulations in effect.
The figure above is a representative schematic of a standard EGR System. Some engines employ the engine’s coolant to reduce the exhaust gas temperature prior to reintroduction to the combustion system further reducing NOX emissions.