Stroke ratio
The stroke ratio is the ratio of the piston stroke to the cylinder diameter in a reciprocating piston engine , especially in a reciprocating piston engine .
A distinction is made between
- Short stroke : stroke ratio <1 (stroke <cylinder diameter)
- Square Huber : stroke ratio ≈ 1 (≈ stroke cylinder diameter), also referred to as "square design"
- Long stroke : stroke ratio> 1 (stroke> cylinder diameter)
Short strokes are favorable for high speeds, since a shorter stroke causes lower linear speed and acceleration forces. They are typical for compact, high-speed reciprocating piston engines, especially gasoline engines .
Large, slow- running engines such as marine diesel engines , on the other hand, are designed as long-stroke engines . Their speed is limited by the cavitation on the directly driven screw. The long stroke results from the permissible mean piston speed . From a stroke ratio of 2 or more , the crank drive is designed with a connecting rod, crosshead guide, piston rod and disc piston instead of a connecting rod and plunger piston .
Typical stroke ratio values are between 0.4 for four-stroke racing engines and up to 5 for marine diesel engines such as the two-stroke MAN B&W 5G45ME diesel engine .
See also
literature
- DIN 1940 standard "Combustion Engines", various editions since July 1946.