Browse Publications Technical Papers 2002-01-1941
2002-06-03

Extended, and Variable, Stroke Reciprocating Internal Combustion Engines 2002-01-1941

A description is given, with a supporting thermodynamic analysis, of a four-stroke Diesel engine concept with the expansion and exhaust strokes exceeding the induction and compression strokes due to the use of a novel linkage connecting the piston to the crankshaft. The advantage of such an arrangement, after allowing for engine internal friction losses, is a reduction of about 8% in specific fuel consumption relative to an otherwise similar conventional Diesel engine. There is also a corresponding reduction of emissions. An extension of the concept, incorporating a slightly more complex linkage, is applicable to spark-ignition engines. In this case the arrangement can be operated more flexibly since the expansion ratio can be adjusted with the engine running. This capability also allows a constant compression ratio to be maintained independently of the selected expansion ratio. Reducing, for spark-ignition engines, the induction and compression strokes while extending the expansion and exhaust strokes correspondingly allows the brake specific fuel consumption to be reduced by about 20% at 30 % of full load. This conclusion was also supported by detailed thermodynamic studies with due allowance being made for engine friction losses.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Members save up to 43% off list price.
Login to see discount.
Special Offer: With TechSelect, you decide what SAE Technical Papers you need, when you need them, and how much you want to pay.
X