Investigation On Emission Improvement Of LC188F Small Utility Engine

The small utility gasoline engine is widely used in garden machinery, agricultural machinery, stand-by power, and also used in industrial area, military area and as the small portable mechanical power for scientific researching. In recent years, the huge demanding for small utility gasoline engine develops very quickly, at same time, the emission problem also become more concerned.As the EPA third phase emission regulation put into effect, research for controlling emission has become a big problem for export. LC188F engine was picked in this topic, for researching the emission by after treatment technology.The author's first research is the thermal reaction condition on LC188F engine for reducing the emission, through changing the instrument of catalytic activity, testing the rule of the thermal reaction with different materials pipes in different oxygen content and temperature conditions. The research shows that when the oxygen content in exhaust gas is more than 4 ~ 6%, there will be obvious thermal reaction in the metal material pipe with CO & HC. And then test the emission on the bench by force the air into the exhaust pipe, studies show that when the air flow reached 40L/min, HC value began to reaction, when the air flow to 60L/min, the HC emission is lowest. But the tests indicates that the reduction does not get the expected value when use of the second air valve, which is natural aspiration. Next, by using the catalytic with second air valve instrument, we get the HC+NOx value to 3.4g/kWh, which is 56% below than the original testing, and meet the EPA tier three regulation.This paper deep introduces the LC188F engine and similar type of engine on thermal reaction condition and the catalyst reaction condition, which give the important preparatory on the after treatment technology using in small utility gasoline engine field.