Low Exhaust Emission System for Small Two-Stroke Cycle Engines,Mitsubishi Heavy Industries Technical Review Vol.38 No.3(2001)

Emission regulations for small utility, lawn, and garden equipment engines went into effect in 1995 in the U.S. Tier 2 standards of the California Air Resource Board (CARB) went into effect in 2000. Reducing emission of small two-stroke cycle engines is thought to be difficult due to incomplete scavenging. Two-stroke cycle engines have many features favoring handheld equipment, so we studied new scavenging system to meet emission standards. We found that hydrocarbon (HC) emission could be reduced to about one third that of conventional engines, meeting the standard. This paper describes the new scavenging technology and the development of 5 new TLE series engine models.