AN OPPOSED-PISTON DIESEL-ENGINE

Typical conventional diesel engine designs are based on arrangements o f single piston and cylinder sets placed sequentially either in-line o r offset (''V'') along the crank-shaft. The development of other engin es, such as the opposed piston type, has been motivated by potential a dvantages seen in such designs, which may not be viable in conventiona l in-line or V engine arrangements. Several alternatives to convention al engine design have been investigated in the past and some aspects o f these designs have been utilized by engine manufacturers. The design and development of a proof-of-concept opposed piston diesel engine is summarized in this paper. An overview of opposed-piston engines is pr esented from early developments to current designs. The engine develop ed in this work is a two stroke and uses four pistons, which move in t wo parallel cylinders that straddle a single crankshaft. A prechamber equipped with a single fuel injector connects the two cylinders, formi ng a single combustion chamber. The methodology of the engine developm ent process is discussed along with details of component design. Exper imental evaluations of the assembled proof-of-concept engine were used for determining feasibility of the design concept. An electric dynamo meter was used to motor the engine and for loading purposes. The dynam ometer is instrumented for monitoring both speed and torque. Engine pa rameters measured include air flow rate, fuel consumption rate, inlet air and exhaust temperatures, and instantaneous cylinder gas pressure as a function of crank position. The results of several testing runs a re presented and discussed.