This content is not included in
your SAE MOBILUS subscription, or you are not logged in.
Cylinder-Pressure-Transducer Mounting Techniques to Maximize Data Accuracy
Annotation ability available
Sector:
Language:
English
Abstract
Engine cylinder-pressure data is generally acquired using piezoelectric pressure transducers because of the many advantages they offer. Unfortunately, a serious and difficult-to-detect disadvantage is variability introduced into the raw data by thermal shock occurring at the transducer face. Transducer manufacturers are aware of this problem and have produced special designs intended to minimize thermally-induced output drift. Although improvements have resulted, the problem continues to exist. However, thermal shock can be reduced by properly mounting the transducer. This study reviews the theoretical principles dictating performance of remote-mounted transducers and examines the influence of the mounting scheme on pressure-data quality.
The three feasible mounting schemes studied were flush mount, remote mount via a single passage, and remote mount via multiple slots. A fourth mounting scheme, namely remote mount via a sintered porous-metal interface, proved infeasible because of excessive pressure drop across the porous metal. The multiple-slot mounting adapter performed best. When properly designed, this adapter can maintain data accuracy while considerably reducing transducer-induced variability relative to flush mounting. For example, measured cyclic variability in indicated mean effective pressure is cut in half at a medium-load condition.
LACK OF ACCURACTE CYLINDER-PRESSURE measurement can produce erroneous trends in experimental correlations and/or limit the extent to which engine performance can be examined. Quartz piezoelectric transducers are generally used to measure cylinder pressure because they have a high frequency response, small size, light weight, low power consumption, and are relatively insensitive to environmental conditions [1]* . However, they are far from perfect devices. Their two main operational disadvantages are (1) variations in output during thermal transients (thermal shock) and (2) the necessity to relate all measurements to an absolute reference pressure. This paper examines strategies to reduce the effects of disadvantage (1), whereas disadvantage (2) is addressed in a separately reported study [2]. The analysis procedure consists of carefully examining experimental pressure data to isolate specifically how, when, where, and why intracycle pressure measurement is affected. Individual-cycle heat release is used to assess the effects of raw-data variability on combustion-performance parameters.
Recommended Content
Technical Paper | Methods of Processing Cylinder-Pressure Transducer Signals to Maximize Data Accuracy |
Technical Paper | Classical Combustion Diagnostics for Engine Research |
Technical Paper | Optimizing Race Engine Performance One Cylinder at a Time |
Authors
Topic
Citation
Randolph, A., "Cylinder-Pressure-Transducer Mounting Techniques to Maximize Data Accuracy," SAE Technical Paper 900171, 1990, https://doi.org/10.4271/900171.Also In
References
- Amann C. A. “Classical Combustion Diagnostics for Engine Research,” SAE Transactions 94 1975 Paper 850395
- Randolph A. L. “Cylinder-Pressure Transducer Signal-Processing Methods to Maximize Data Accuracy,” SAE 1990
- Lancaster D. R. Krieger R. B. Lienesch J. H. “Measurement and Analysis of Engine Pressure Data,” SAE Transactions 84 1975 Paper 750026
- 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
- Kach R. A. Adamczyk A. A. “Effects of Thermal Loading on Pressure Measurement in a Combustion Bomb,” The Combustion Institute Eastern States Section Clearwater, FL 1984
- Daniele G. D. “Pressure Measuring Techniques in I. C. E.,” Meccanica 12 3 September 1977
- Stein R. A. Mencik D. Z. Warren C. C. “Effect of Thermal Strain on Measurement of Cylinder Pressure,” SAE Transactions 96 1987 Paper 870455
- Busse D. W. “Quartz Transducers for Precision Under Pressure,” Mechanical Engineering 109 5 May 1987
- Schafer H. J. Krull O. Maege B. “Thermal Stress on a Piezoelectric Pressure Transducer in the Combustion Chamber of an SiEngine,” SAE Transactions 94 1985 Paper 850375
- Shi S. X. Sheng H. Z. “Numerical Simulation and Digital Signal Processing in Measurements of Cylinder Pressure of Internal Combustion Engines,” Proceedings of the Institution of Mechanical Engineers International Conference on Computers in Engine Technology March 1987
- Mijamoto N. Murayama T. “Improvement of the Dynamic Characteristics in the Connecting Passages for Measuring High Frequency Pressure Diagrams,” SAE Transactions 95 1986 Paper 861277
- Evers L. W. “Spark Plug Pressure Transducers for Measuring Indicated Work,” SAE Paper 780148 1978
- Van Aken C. “Adapter Errors in Indicator Diagrams of Combustion Engines,” Proceedings of the Institute of Mechanical Engineering 191 August 1977 125 134
- Martin H. K. Plee S. L. Remboski D. J. “Burn Modes and Prior-Cycle Effects on Cyclic Variations in Lean-Burn Spark-Ignition Engine Combustion,” SAE Paper 880201 1988
- Quader A. A. “What Limits Lean Operation in Spark Ignition Engines -- Flame Initiation or Propagation?” SAE Transactions 85 1976 Paper 760760
- N.A.C.A. Report 1300 “Basic Considerations in the Combustion of Hydrocarbon Fuels in Air,” National Advisory Committee for Aeronautics 1957
- Tse F. S. Morse I. E. Hinkle R. T. Mechanical Vibrations Allyn and Bacon Boston 1963
- Kanury A. M. Introduction to Combustion Phenomena Gordon and Breach Science Publishers New York 1975
- Lewis B. von Elbe G. Combustion, Flames and Explosions of Gases Academic Press New York 1961
- Lavoie G. A. “Correlations of Combustion Data for S. I. Engine Calculations - Laminar Flame Speed, Quench Distance and Global Reaction Rates,” SAE Paper 780229 1978
- Perry R. H. Chilton C. H. Chemical Engineers' Handbook McGraw-Hill Book Company New York 1973