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Abstract |
Spark Advance for Optimal Efficiency
Most of todays spark-advance controllers operate in open loop but
there are several benefits of using feed-back or adaptive schemes
based on variables deduced from the cylinder pressure. A systematic
study of how different engine conditions change the deduced variables,
at optimal ignition timing, is performed. The analysis is performed
using a one-zone heat-release model and varying the model parameters.
The deduced variables that are studied are: position of the pressure
peak, mass fraction burned levels of 30\%, 45\%, 50\%, and 90\%, and
the pressure ratio.
For MBT timing the position for 45\% mass fraction burned changed
least under a large variety of changes in burn rate. Cycle-to-cycle
variations do not have a significant effect and it suffices to
evaluate the mean values for the burn rate parameters. The pressure
ratio produces values similar to the mass fraction burned and requires
no separate treatment.
Lars Eriksson
1999
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Senast uppdaterad: 2021-11-10
