Browse Publications Technical Papers 2000-01-0933
2000-03-06

Closed-Loop Control of Spark Advance and Air-Fuel Ratio in SI Engines Using Cylinder Pressure 2000-01-0933

The introduction of inexpensive cylinder pressure sensors provides new opportunities for precise engine control. This paper presents a control strategy of spark advance and air-fuel ratio based upon cylinder pressure for spark ignition engines. In order to extend the cylinder pressure based engine control to a wide range of engine speeds, the appropriate choice of control parameters is important as well as essential.
For this control scheme, peak pressure and its location for each cylinder during every engine cycle are the major parameters for controlling the air-fuel ratio and spark timing. However, the conventional method requires the measurement of cylinder pressure at every crank angle degree to determine the peak pressure and its location. In this study, the peak pressure and its location were estimated, using a multi-layer feedforward neural network, which needs only five cylinder pressure samples at -40°, -20°, 0°, 20°, and 40° after TDC.
The neural network plays an important role in mitigating the A/D conversion load of an electronic controller by increasing the sampling interval from 1°crank angle (CA) to 20°CA. The estimated location of the peak pressure can be regarded as a good index for combustion phasing, and can also be used as an MBT control parameter. The peak pressure reflects the air-fuel ratio from rich mixture to lean mixture near the lean misfire limit, and can be used as an air-fuel ratio control parameter as well.
The feasibility of this methodology was closely examined through steady and transient engine operations to control spark advance and air-fuel ratio. Moreover, a commercial two-liter four-cylinder engine was employed in this experiment. The experimental results revealed a favorable agreement between the real MBT and target air-fuel ratio.

SAE MOBILUS

Subscribers can view annotate, and download all of SAE's content. Learn More »

Access SAE MOBILUS »

Preview Document Add to Cart
Members save up to 16% off list price.
Login to see discount.
Special Offer: Download multiple Technical Papers each year? TechSelect is a cost-effective subscription option to select and download 12-100 full-text Technical Papers per year. Find more information here.
We also recommend:
TECHNICAL PAPER

Correlation of Air Fuel Ratio with Ionization Signal Metrics in a Multicylinder Spark Ignited Engine

2009-01-0584

View Details

TECHNICAL PAPER

Robust Tuning of Individual Cylinders AFR in SI Engines with the Ion Current

2005-01-0020

View Details

TECHNICAL PAPER

Estimation of Air Fuel Ratio of a SI Engine from Exhaust Gas Temperature at Cold Start Condition

2002-01-1667

View Details

X