Since the beginning of combustion engine design, the need for higher power output and at the same time lower weight is mandatory. More severe exhaust emission regulations and a higher customer sensibility regarding the environmental friendliness of internal combustion engines lead to an implementation of the four-stroke technology into most of the applications of spark ignition engines. In comparison with the conventional two-stroke operation cycle the four stroke working principle produces less hydrocarbon and particulate exhaust emissions. A disadvantage of four stroke engines is the low power and torque output, comparing the same engine displacement, that is restricted to a wide range of applications. The four stroke process must be enhanced by boosting the delivery ratio with supercharging methods, to reach the high end emission and performance values that are required for a new scooter drive unit. An efficient and economic method to increase the performance of four stroke engines can be crankcase supercharging. This paper describes the development history beginning with the first idea up to a running research prototype of a 50 cc scooter engine. The major target in this research program was to develop a supercharged four-stroke engine with a closed loop lubrication system. The thermodynamic layout of the engine and the development of an oil separating system have been carried out with the help of simulation tools and development work on a flow test bench. By use of donor parts from serial engines available on the market, a prototype engine was set up and the simulation results were verified on the engine test bench. Finally the prototype engine was implemented in a scooter and tested in comparison with modern scooters. The crankcase supercharging of a single cylinder engine seems to be a smart solution for increasing the performance of an engine in a displacement restricted market field. The performance and emission results promise a good market chance for this concept.
Crankcase supercharging a solution for small capacity four stroke engines
Development Trends of Motorcycles II, International Conference Development Trends of Motorcycles, 3 ; 156-180
2005
25 Seiten, 30 Bilder, 13 Quellen
Conference paper
English
Crankcase Supercharging - a Solution for Small Capacity Four Stroke Engines
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