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Estimating Instantaneous Losses Within a Firing IC Engine Using Synthetic Variables
Technical Paper
2011-01-0611
ISSN: 0148-7191, e-ISSN: 2688-3627
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English
Abstract
A new method for instantaneous friction estimation in firing internal combustion engines has been developed in the Powertrain Control Research Laboratory (PCRL) at the University of Wisconsin - Madison. This Synthetic Variable approach, which has previously been used for combustion quality diagnostics, focuses on carefully measuring instantaneous engine speed and other easily measurable engine variables and combining them with dynamic models of other engine processes. This approach numerically strips away the dynamic effects that mask friction effects on engine speed and reveals friction estimates with clarity. This information could be useful for engine designers and developers to assist in accurately understanding the sources of instantaneous friction within the running engine.
The friction results from these studies have been very encouraging. Accuracy was found to be within 0.5% on average in the data sets where friction was based on measurable engine variables, with this decreasing to within about 5% when the friction applied was more arbitrary. The exception to these numbers occurs in the immediate vicinity of piston TDC, where errors in crankshaft acceleration estimation (due to the steep transients at combustion) carry through the model and degrade the friction estimation. A statistical analysis method that was used to determine the relative contribution to overall friction from individual components or locations within the engine is also presented.
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Citation
Neu, A., Moskwa, J., and Robinson, P., "Estimating Instantaneous Losses Within a Firing IC Engine Using Synthetic Variables," SAE Technical Paper 2011-01-0611, 2011, https://doi.org/10.4271/2011-01-0611.Also In
References
- Moskwa, J.J. Wang, W. “Simplified Engine Combustion Diagnostics Using ‘Synthetic’ Variables,” SAE Technical Paper 2000-01-0364 2000 10.4271/2000-01-0364
- Neu, A.K. “Applying the Synthetic Variable Approach to the Estimation of Instantaneous Friction in a Running Engine,” M.S. thesis Mechanical Engineering Department, University of Wisconsin Madison, Wisconsin 2010
- Wang, W. “Dynamic Powertrain System Modeling and Simulation with Applications for Diagnostics, Design, and Control,” Ph.D. thesis Mechanical Engineering Department, University of Wisconsin Madison, Wisconsin 2000
- Porter, F.P. “Harmonic Coefficients of Engine Torque Curves” Journal of Applied Mechanics March 1943