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.
UKF-based estimation of indicated torque for IC engines utilizing nonlinear two-inertia model
The estimation of the indicated torque for internal combustion (IC) engines is important for control, diagnosis and performance evaluation. If adequate sensors were available for pressure measurement in each cylinder, the indicated torque estimation would be easier. Those sensors, however, cannot be utilized generally from cost and installation space viewpoints. Hence, this paper considers an indicated torque estimation method utilizing only the crank-shaft angle information, which can be obtained even for commercial cars, instead of pressure sensors. The use of the crankshaft angle causes a problem that an unexpected vibration contaminating the angle information deteriorates the torque estimation accuracy because vibration frequency is relatively close to the combustion cycle. Thus, the engine torque estimation can be formulated as an observer design under model uncertainty and nonlinearity. In addition, this observer design problem is classified into an unknown input observer design because the engine torque or the combustion pressure as input to the engine system cannot be measured directly. To solve the design problem, this paper proposes the introduction of a nonlinear two-inertia model to catch the unexpected vibration, and an UKF-based I-type disturbance observer to estimate the indicated torque and the system state. The effectiveness of the proposed method is verified through experiments.
Individual cylinder knock control by detecting cylinder pressure
To improve available power, tolerance to variation in fuel octane number and high engine speed knock control, an individual cylinder knock control has been developed. Knock are detected by spark plug washer transducers, which indicate individual cylinder pressures.) Last year the authors read a paper entitled ''Cylinder Pressure Vibration Analysis Indicates Accurate Knock Detection''. They read continuously on the following items. Spark plug washer transducers - These are piezoelectric ceramic rings which fit beneath individual spark plugs. These can detect knock at high engine speed, and are very durable. Knock detection and control algorithm - Knock is indicated by the transducer's cylinder pressure vibration signal. When knock occurs in the cylinder, the ignition timing of the cylinder is controlled. During the transient condition, control response is fast by learning control. Fail safe - At transducer trouble, the ignition timing of the cylinder is controlled by other transducer signals. Electric control unit - It is included in NISSANs Electronic Concentrated Engine Control System (ECCS). Effects of this control - It improved WOT torque by 7-15%, torelance to variation in fuel octane number, and high engine speed control performance.