Torque ratio concept for combustion phasing detection of a spark ignited engine
This paper presents a method for estimating combustion phasing of a five cylinder, four stroke, spark ignited engine, equipped with a crankshaft based torque sensor. A new measure for combustion phasing based on the torque signal is derived for a single cylinder engine. The measure is called 50% torque ratio. A validation of the measure is done by comparing to the related cylinder pressure based 50% pressure ratio measure. A method is also presented to apply the torque ratio measure to a multi-cylinder engine. A physical model for the instantaneous torque measurement is described handling the torque contributions from all individual cylinders in all combustion phases. The torque contribution from the combusting cylinder is isolated and analyzed by the torque ratio method to find the combustion phasing. The multi-cylinder algorithm is validated on torque and cylinder pressure data from a five cylinder Volvo V70 engine.
An Analytic Model for Cylinder Pressure in a Four Stroke SI Engine
An analytic model for cylinder pressures in spark ignited engines is developed and validated. The main result is a model expressed in closed form that describe the in-cylinder pressure development of an SI engine. The method is based on a parameterization of the ideal Otto cycle and takes variations in spark advance and air-to-fuel ratio into account. The model consists of a set of tuning parameters that all have a physical meaning. Experimental validation on two engines show that it is possible to describe the in-cylinder pressure of a spark ignited combustion engine operating close to stoichiometric conditions, as a function of crank angle, manifold pressure, manifold temperature and spark timing.
Closed Loop Ignition Control by Ionization Current Interpretation
The main result of this paper is a real-time closed loop demonstration of spark advance control by interpretation of ionization current signals. The advantages of such a system is quantified. The i ...