Working area (piston machine)
In piston machines, the working space denotes the maximum total volume that is limited by the piston . In the case of internal combustion engines , it corresponds to the expansion space that is reached as the maximum volume when the piston passes through bottom dead center (BDC), especially in the case of a reciprocating engine . Its volume ratio to the minimum compression volume or residual volume (at top dead center OT) results in the geometric compression ratio ε.
In contrast, the displacement describes the difference between the total volume in BDC and compression volume in TDC.
The combustion chamber , on the other hand, is the variable volume that is determined by the time-dependent piston position and is only identical to the working chamber at bottom dead center.
Especially as a combustion chamber in the narrower sense, only the remaining volume at top dead center OT, in which ignition takes place, is sometimes understood. However, this point of view only ideally fits the gasoline engine ( constant space process ). At least for the diesel engine ( equal pressure process ), the combustion only begins here and continues a long way with the downward movement of the piston during the expansion phase.
literature
- DIN 1940 standard "Combustion Engines", various editions since July 1946