Stochastic Knock Control for Improved Efficiency
Increasing the efficiency and performance of internal combustion engines is always of interest in
the automotive industry. One limiting factor to achieve this in gasoline combustion engines is the
ignition timing which can not always be set where optimal ignition efficiency and performance is
obtained. This is due to the knock phenomenon which is an abnormal combustion process that
can damage the engine. Due to knock, a feedback controller which sets the ignition timing at
the best possible value without the risk of harming the engine is required. In this thesis, a statistically driven knock intensity simulation environment based on the Burr Type XII distribution
model was set up. In the simulation environment, different stochastic knock feedback controllers
were implemented along with background noise estimation techniques used in the knock detection system. The feedback controllers were evaluated against the conventional knock controller
commonly used in today’s engines in terms of ignition angle and transient response. The results from the simulation environment showed that a more advanced mean ignition angle can be
achieved with stochastic based knock control strategies with the same knock-rate and without
lessening the fast transient response achieved from the conventional strategy. To evaluate the
results, some of the controllers were implemented in a four cylinder two-liter four stroke Volvo
engine with similar results.
Jonas Vedin and Robert Widén
2019
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Senast uppdaterad: 2021-11-10
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