"Toyota Diesel Clean Advanced Technology (D-CAT) combines various elements working together to deliver significant gains in emission control; these include the maintenance-free Diesel Particulate and NOx Reduction system (DPNR)."
How does it work?
The DPNR is the only catalyst in the world that simultaneously reduces Nitrogen Oxide and Particulate Matter from diesel engines. The operation of the DPNR catalyst relies on the D-CAT engine management system varying the air-fuel ratio in the exhaust gasses.
To do this, an Exhaust Port Injector (EPI) is fitted which, at the critical moment, injects fuel into the exhaust gas flow to create a ‘rich spike’ aiding the DPNR catalyst in reducing Nitrogen Oxide and Particulate Matter. The EPI is also used to perform the sulphur discharge control.
A high-efficiency Exhaust Gas Recirculation cooler (EGR) is used to reduce the temperature of the exhaust gasses being re-circulated into the combustion chamber, and so increases their density. This uses an electrically-activated valve that takes only 50 milliseconds to open for more accurate control from the engine ECU.
The recirculation of a small amount of exhaust gases into the next combustion cycles helps to prevent the generation of harmful emission gases.