2-CYCLE ENGINE OF AN ACTIVE THERMOATMOSPHERE COMBUSTION TYPE

摘要

A 2-CYCLE ENGINE OF AN ACTIVE THERMOATMOSPHERE COMBUSTION TYPE Disclosed is a 2-cycle engine having a scavenging passage communicating the crank case with the combustion chamber. The scavenging passage comprises a first passage and a second passage. The first passage has a long length and a small cross-sectional area for causing a fresh combustible mixture to flow at a high speed. The second passage has a short length and a large cross-sectional area for causing a fresh combustible mixture to flow at a low speed. The vaporization of the fresh combustible mixture is promoted in the first passage and, in addition, the fresh combustible mixture flows into the combustion chamber at a low speed. As a result of this, an active thermoatmosphere combustion is caused in the combustion chamber.