Stößzyklus

Stößzyklus is a term used in some German-language technical writings to describe the mechanical sequence of a reciprocating piston engine as the piston moves within a cylinder during one complete cycle. The term emphasizes the piston’s motion (Stößel) relative to the crankshaft, but it is less common than other expressions such as Hubzyklus or Arbeitszyklus.

In a four-stroke engine, a single Stößzyklus comprises four distinct strokes performed over two revolutions of the crankshaft: Einlass (intake), Kompression (compression), Arbeit (power/expansion), and Auspuff (exhaust). The intake stroke brings the air–fuel mixture into the cylinder, the compression stroke raises the pressure, the power stroke releases energy from combustion, and the exhaust stroke expels combustion gases. In a two-stroke engine, these processes occur over two strokes per crankshaft revolution, with scavenging and charging often integrated through ports or auxiliary means.

Mechanically, the cycle is governed by the piston, connecting rod, crankshaft, valves or ports, and the timing mechanism (camshaft or electronic control). Valve timing and fuel delivery shape the actual thermodynamic path, which engineers often describe using standard cycles such as the Otto cycle for spark-ignition engines or the Diesel cycle for compression-ignition engines. Real-world efficiency and emissions are influenced by compression ratio, ignition timing, air handling, and exhaust scavenging—elements that belong to the broader Arbeitszyklus of the engine.

Terminology: While Stößzyklus appears in some sources, it is not universally used in modern engineering literature. More common terms include Hubzyklus, Arbeitszyklus, or the specific four-stroke or two-stroke cycle names. See also Otto cycle, Diesel cycle, internal combustion engine, piston.