An Experimental Development of a New U-Cylinder Uniflow Scavenged Engine 850181
The U-cylinder uniflow scavenged engine is a type of two-stroke cycle engine in which the scavenging medium proceeds along a one-way, inverted U-shaped path. Engines of this kind were invented by Lucas in 1905 and produced as commercial engines also in Japan since about 1955. But these engines have disappeared from production all over the world.
A new engine has been made by modifying one of the above-mentioned commercial engines. The performance of the new engine is better than the Schnuerle scavenged engines and the concentration of HC is less than one-half of that of the latter.
Furthermore, the following items were clarified by the experiments:
The throttling ratio and required velocity as defined in this paper are useful for the port design.
It has been confirmed that U-cylinder uniflow scavenging is one of the best systems for scavenging.
Although it seems better to precede the crankangle of the exhaust side piston by 10 deg. relative to the scavenging side piston, this was, however, not proved by the experiments.