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Four-Stroke Engine

Heat Engine

A four-stroke engine, also called a four-cycle engine, is an internal combustion engine in which the piston completes four separate strokes, intake, compression, combustion and exhaust, while turning the crankshaft through two full revolutions. Four-stroke engines are the most common internal combustion engine design for motorized land transport, used in automobiles, trucks, diesel trains, light aircraft and motorcycles; their major alternative design is the two-stroke cycle engine.

Facts
Technology Type
Internal combustion heat engine 1
Invented Year
1876 1
Year Nicolaus Otto and Eugen Langen completed the first internal combustion engine to compress the fuel mixture before combustion, per the cited source; several engineers including Etienne Lenoir worked toward the four-stroke principle earlier, so this date marks the first working compressed-charge four-stroke engine rather than a single uncontested moment of invention.
Classification
Maturity
TRL 9: Actual System Proven in Operational Environment 1
Sources
1. Wikipedia: Four-stroke engine
Wikipedia
  • Four-stroke engine, lead section, engine definition
    A four-stroke (also four-cycle) engine is an internal combustion (IC) engine in which the piston completes four separate strokes while turning the crankshaft.
  • Four-stroke engine, history of development section
    By 1876, Otto and Langen succeeded in creating the first internal combustion engine that compressed the fuel mixture prior to combustion for far higher efficiency than any engine created to this time.
  • Technology maturity, entity description (description property itself uncited on this atlas; cited against the entity's own live or freshly minted Wikipedia source instead)
    Four-stroke engines are the most common internal combustion engine design for motorized land transport, used in automobiles, trucks, diesel trains, light aircraft and motorcycles; their major alternative design is the two-stroke cycle engine.
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