Abstract:

A two-valve CN-III diesel engine was improved by designs and tests to meet the CN (China)-IV
emission regulation. The improved designs involved upgrading the electronic control system, redesigning the
combustion chamber, optimizing the injector and the turbocharger, adopting the exhaust gas recirculation (EGR)
and the advanced after-treatment technology. The turbocharger, the combustion chamber, the fuel supply
advance angle, the rail pressure and EGR were optimized and calibrated. The performance tests, the emission
tests and the noise tests were completed. The EGR system and the calibration strategy were confirmed by
measuring and analyzing the parameters ofpower, torque, fuel consumption, smoke, emission, EGR rates,
and the idle speed noise. The vehicle was calibrated by OBD (on-board diagnostic). The results show that the
diesel engine meets the CN-IV emission regulation, and the idle speed noise decreased from 74 dB to 70 dB by
improving emission and performance.

Key words: diesel engines, emission regulations of CN-IV, exhaust gas recirculation (EGR), combustion room;
injector, turbocharger, on-board diagnostic (OBD)