This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Cylinder Pressure Data Quality Checks and Procedures to Maximize Data Accuracy
Technical Paper
2006-01-1346
ISSN: 0148-7191, e-ISSN: 2688-3627
Annotation ability available
Sector:
Language:
English
Abstract
Cylinder pressure data is so completely integral to the combustion system development process that ensuring measurements of the highest possible accuracy is of paramount importance. Three main areas of the pressure measurement and analysis process control the accuracy of measured cylinder pressure and its derived metrics:
-
1)
Association of the pressure data to the engine's crankshaft position or cylinder volume
-
2)
Pegging, or referencing, the pressure sensor output to a known, absolute pressure level
-
3)
The raw, relative pressure output of the piezoelectric cylinder pressure sensor
Certain cylinder pressure-based metrics, such as mean effective pressures (MEP) and heat release parameters, require knowledge of the cylinder volume associated with the sampled pressure data. Accurate determination of the cylinder volume is dependent on knowing the rotational position of the crankshaft. New, objective methodologies for use with commercially available top dead center (TDC) location probes are presented. These allow precise and robust phasing of a crankshaft position sensor (encoder) to engine crankshaft rotational position.
While cylinder pressure pegging accuracy has no effect on calculated mean effective pressures or location of peak pressure, it does influence other critical combustion metrics such as burn durations and Polytropic coefficients. The influences of pegging errors on these metrics are compared, and the sensitivities of effected metrics are presented.
Many sources of error can that affect the raw, relative pressure signal of the piezoelectric sensor. Among these are thermal shock and variations in sensitivity as a function of the mean operating temperature and pressure of the transducer.
Thermal shock refers to a short term (effects exist within a single engine cycle) shift in sensor output brought about by high rates of heat flux to the sensing element.
While modern, high-end transducers incorporate design features to minimize these effects, they can still exhibit significant errors if they are not properly mounted and the data is not collected and analyzed with the proper care and techniques. Techniques and metrics which are useful for evaluating cylinder pressure data plausibility and quality are introduced. These metrics allow quick and robust identification of the presence of thermal shock.
Recommended Content
Authors
Citation
Davis, R. and Patterson, G., "Cylinder Pressure Data Quality Checks and Procedures to Maximize Data Accuracy," SAE Technical Paper 2006-01-1346, 2006, https://doi.org/10.4271/2006-01-1346.Also In
Combustion and Flow Diagnostics and Fundamental Advances in Thermal Fluid Sciences 2006
Number: SP-2015; Published: 2006-04-03
Number: SP-2015; Published: 2006-04-03
References
- Lancaster, D. R. Krieger, R. B. Lienesch, J. H. “Measurement and Analysis of Engine Pressure Data,” SAE 750026
- Randolph, A. “Methods of Processing Cylinder-Pressure Transducer Signals to Maximize Data Accuracy,” SAE 900170
- Randolph, A. “Cylinder-Pressure Transducer Mounting Techniques to Maximize Data Accuracy,” SAE 900171
- Rassweiler, G. M. Withrow, L. “Motion Pictures of Engine Flames, Correlated with Pressure Cards,” SAE Transactions 42 1938
- Amann, C. A. “Classical Combustion Diagnostics for Engine Research” SAE Paper 850395 1985
- Puzinauskas, P, V. Mathis, W. M. Dzieciuch, M. A. “Quantification and Modeling the Effects of Thermal Shock on Combustion Pressure Transducers”’ SAE Paper 2001-01-3491 2001
- Higuma, A. Suzuki, T. Yoshida, M. Oguri, Y. Minoyama, T. “Improvement of Error in Piezoelectric Pressure Transducer”’ SAE Paper 1999-01-0207 1999
- Schafer, H. J. Krull, O. Maege, B. Thermal Stress on piezoelectric Pressure Transducer in the Combustion Chamber of an SI-Engine,” SAE Paper 850375 1985
- Stein, R. A. Mencik, D. Z. Warren, C. C. “Effect of Thermal Strain on Measurement of Cylinder Pressure,” SAE Paper 870455 1987
- Daniele, G. D. “Pressure Measuring Techniques in I.C.E.,” Meccanica 12 3 September 1977
- Pischinger, R. Krassnig, G. Glaser, J. “Problems of Pressure Indication in Internal Combustion Engines,” International Symposium on Diagnostics and Modeling of Combustion in Reciprocating Engines, JSME, SAEJ, MESJ, COMODIA 1985 Tokyo 1985 539 549