Recently, diesel engine manufacturers have been improving the tolerance of fuel injection quantity and timing in response to the strengthening of emissions regulations and the introduction of various kinds of diesel fuels. This paper describes the Intelligent Accuracy Refinement Technology (i-ART) system, which has been developed as a way of achieving substantially improved tolerances.
The i-ART system consists of a fuel pressure sensor installed in the injectors. It calculates the injection quantity and timing at high speed using a dedicated microcomputer designed for pressure waveform analysis. As the injector can directly measure the fuel injection pressure waveform for each injection, it can compensate the injection quantity and timing tolerance at any time.
Toyota Motor Corporation has introduced this system in Brazilian market vehicles. In Brazil, the PROCONVE L6 emissions regulations will be introduced in 2012, and the market also uses various kinds of diesel fuels. The i-ART system enables diesel engines to satisfy these new regulations, and drastically improves fuel consumption by adopting a low compression ratio and 3-pilot injection control. A cetane number detection control has also been developed using the i-ART system characteristics. As a result, even if a vehicle is driven using low or high cetane number diesel fuel, the same level of combustion noise is achieved by adjusting the engine calibration based on the detected cetane number. Engines equipped with this system have successfully passed the new emissions regulations and are compatible with the various kinds of diesel fuels used in Brazil.