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Measurement of Engine Friction Power by Using Inertia Tests
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English
Abstract
A simple yet reliable method to evaluate the overall friction power of an internal combustion engine is proposed. The method is based on the measurement of the angular deceleration of the engine speed. The tested engine is coupled to a flywheel having a known high moment of inertia, fired and accelerated to a high engine speed. The system is kept running until steady conditions are attained. Then, the ignition system is shut-off, and the engine speed deceleration vs. time, α, is recorded. The total friction-mean-effective-pressure, tfmep vs. time, may then be evaluated from the fundamental relationship between the two (tfmep=2πIα/Vd, where, Vd is the engine displacement volume, and I is the moment of inertia of the integrated system).
The proposed method, is a modification of the direct motoring method, in which the engine is motored by an external means under conditions as close as possible to firing. In the present method, the inertia method, there is no need for an external means for motoring, the test is performed under realistic piston, cylinder and lubricant temperatures, the total friction mep curve vs. engine speed is readily obtained by a single test, and the upper speed is limited only by the speed limit of the engine itself.
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Citation
Harari, R. and Sher, E., "Measurement of Engine Friction Power by Using Inertia Tests," SAE Technical Paper 950028, 1995, https://doi.org/10.4271/950028.Also In
References
- Heywood, J.B. Internal Combustion Engine Fundamentals McGraw-Hill 1988
- Gish, R.E. McCullough, J.D. Retzloff, J.B. Mueller, H.T. “Determination of True Engine Friction” SAE Trans. 66 649 661 1958
- Brown, W.L. “The Caterpillar IMEP Meter and Engine Friction” SAE paper No. 730150 1973
- Sher, E. “Scavenging the Two-Stroke Engine” Prog. in Energy and Combust. Sci. 16 95 124 1990
- Patton, K.J. Nitschke, R.G. Heywood, J.B. “Development and Evaluation of a Friction Model for Spark-Ignition Engines” SAE paper No. 890836 1989
- Barnes-Moss, H.W. “A Designer's Viewpoint” IMechE Conference on Passenger Car Engines London 133 147 1975
- Sher, E. “Flattening the Torque Curve of a Two-Stroke Engine with a Fluid Diode Installed at the Scavenge Port” SAE paper No. 830092 1983