Study On The Emission And The Air Fuel Ratio Control Strategy For A Honda EC2500C Engine Fuelling With LPG

This paper presents the experiment on Honda EC2500C engine fuelling with LPG. With the analysis of the engine emission of HC, NO, CO, the result showed that the emission of HC and NO decreased gradually with the increment of engine speed and increased with the increment of power. When the engine running at low speed, lean mixture was adapted. The air fuel ratio was controlled between 1. 05~1. 10, the emission of the HC was small; When the engine running in high speed, no matter whether the lean mixture was adapted, the emission of HC was always small. The emission of NO was high in conditions of low speed and heavy load and was small in conditions of high speed and light load. When the engine using LPG, the emission of CO was reduced greatly and continued decreasing with the increment of air fuel ratio. Basing on the result, the air fuel ratio control strategy is concluded: when the output power of engine is less than 70% of the rated power, the air fuel ratio between 1. 05~ 1. 10 is controlled; When the output power of engine is larger than 70% of the rated power, the engine running in high speed, the stoichiometric air fuel ratio running method is applied.