Two New Engines For Avensis | Part Two

Like the advances in hybrid power technology in the new generation Prius, the introduction of D-CAT demonstrates Toyota’s continuing commitment to engineering vehicle powertrains that have a less harmful impact on the natural environment.

The four-cylinder 2.4 Di engine is the largest capacity direct injection petrol engine in the European D segment and is matched to a new, lightweight five-speed multi-mode automatic transmission. It is the first time Toyota has combined a five-speed automatic with a four-cylinder engine, achieving useful gains in torque from a transmission that is lighter and more compact than the four-speed unit.

New Levels Of Clean Diesel Performance

The Toyota D-CAT system was first shown as a concept in 2000. In early 2004 it will become a production reality with D-CAT making its debut in the new Avensis range and offering new low levels of exhaust emissions for a production diesel engine.

Toyota D-CAT achieves its ground-breaking clean performance through the integration of a series of advanced engine technologies. In creating the engine, Toyota took the existing 2.0-litre D-4D and modified or added 30 key components. The advances made are witnessed by Toyota being granted 1,622 new patents for the development of the system.

At the heart of the D-CAT engine is the DPNR (Diesel Particulate NOx Reduction) four-way catalyst. This marks a world first in achieving continuous and simultaneous filtering of nitrogen oxides and particulate matter in exhaust emissions.

The DPNR catalyst was created by incorporating a particulate filter into the three-way NOx catalyst used in Toyota’s lean-burn petrol engine. Its effective operation relies on the engine management system being able to vary the fuel-air ratio in the exhaust gases. This has been made possible with the addition of a fifth injection nozzle, located in the exhaust port. At a critical moment, fuel is injected downstream of the exhaust manifold to create the right operating conditions in the DPNR catalyst. This ‘rich’ spike allows the DPNR catalyst to release and reduce the NOx it has stored.

continues... | Part Three
Published 23 September 2003 Melanie Carter

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