Degree of catch

The degree of catch is a dimensionless number in technology . It provides information about the proportion of a substance that was accepted after the offer was completed (how much substance was "captured"). The degree of trapping is also known as the degree of trapping (English: trapping efficiency ). ${\ textstyle \ lambda _ {z}}$ ${\ textstyle \ eta _ {tr}}$

Degree of catch for two-stroke engines

The trapping efficiency is mainly used in engine, the gas exchange goodness of a two-stroke engine to assess qualitatively. Here, the degree of capture denotes the ratio of the fresh cargo mass to the total inflowing cargo mass. Since, in the case of slot-controlled two-stroke engines, short-circuit flushing causes considerable amounts of unburned hydrocarbons (fuel) to escape into the environment through the outlet, the proportion of fresh charge trapped in the cylinder is of great importance. The degree of catch λ is calculated as follows:

{\ displaystyle \ lambda _ {f} = {\ frac {m_ {Fr}} {m_ {Fr} + m_ {Sp}}}}

${\ textstyle m_ {Fr}}$ is the fresh charge mass remaining in the cylinder after the charge cycle, which is described by the degree of delivery , and the flushing mass, i.e. the mass of fresh charge that escapes through the outlet. ${\ textstyle m_ {Sp}}$

The degree of capture can be calculated for both oxygen and hydrocarbons in the exhaust gas.

Degree of catch in the piston cooling

Another use of the key figure is to consider piston cooling. In reciprocating engines , oil is sprayed from below against the piston crown. Here the piston crown "catches" the oil offered for cooling.

literature

DIN 1940: 1976-12: Internal combustion engines; Reciprocating engines, terms, symbols, units
Günter P. Merker, Rüdiger Teichmann (Ed.): Basics of internal combustion engines . 9th edition. Springer Fachmedien, Wiesbaden 2019, ISBN 978-3-658-23556-7 , 25.2 Important parameters of the gas exchange (extract from DIN 1940), p. 671 ff .

Individual evidence

^ ^A ^b Rudolf Pischinger, Manfred Kell, Theodor Sams: Thermodynamics of the internal combustion engine . 3. Edition. Springer Verlag, Vienna 2009, ISBN 978-3-211-99276-0 , 4.2.6.1 Parameters of gas exchange, equation 4.165 .
↑ Günter P. Merker, Rüdiger Teichmann (Ed.): Fundamentals of internal combustion engines . 9th edition. Springer Fachmedien, Wiesbaden 2019, ISBN 978-3-658-23556-7 , 25.2 Important parameters of the gas exchange (extract from DIN 1940), p. 672 .
↑ Eduard Köhler, Rudolf Flierl: Internal combustion engines . Engine mechanics, calculation and design of the reciprocating engine. 6th edition. Vieweg + Teubner Verlag, Wiesbaden 2011, ISBN 978-3-8348-1486-9 , 4.2.6.2 Thermal stress on the piston.

[Pischinger-1] A ^b Rudolf Pischinger, Manfred Kell, Theodor Sams: Thermodynamics of the internal combustion engine . 3. Edition. Springer Verlag, Vienna 2009, ISBN 978-3-211-99276-0 , 4.2.6.1 Parameters of gas exchange, equation 4.165 .

[2] Günter P. Merker, Rüdiger Teichmann (Ed.): Fundamentals of internal combustion engines . 9th edition. Springer Fachmedien, Wiesbaden 2019, ISBN 978-3-658-23556-7 , 25.2 Important parameters of the gas exchange (extract from DIN 1940), p. 672 .

[3] Eduard Köhler, Rudolf Flierl: Internal combustion engines . Engine mechanics, calculation and design of the reciprocating engine. 6th edition. Vieweg + Teubner Verlag, Wiesbaden 2011, ISBN 978-3-8348-1486-9 , 4.2.6.2 Thermal stress on the piston.