LiU startsida
Abstract |
Cylinder volume function for SVC engines
One of the features of the SAAB Variable Compression engine (SVC) is
its possibility to change the compression by tilting the top of
the engine. Due to the change in geometry, the standard equation used to
calculate the cylinder volume as function of crank angle may not give
sufficiently accurate result. A new cylinder volume function, that is specially designed for the
SVC, is derived and described. It is written on the form V(theta,v) =
V_c(v)+V_d(theta,v), where theta is the crank angle, v the tilt
angle, V_c the clearance volume, and V_d the volume displaced by
the piston. It is shown that the biggest relative deviation between the
standard volume function and the SVC volume function is approximately
6\%. It is also shown that by adjusting the crank angle input to the
standard volume function so that the TDC coincide with the actual TDC,
that is V(theta,v) = V_c(v)+V_{std}(theta-theta_{TDC}), the
relative error caused by using the standard volume function is reduced
by a factor 10.
Ylva Nilsson
2001
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Last updated: 2021-11-10
