EFFECTS OF STRUCTURAL DEFORMATIONS OF THE CRANK-SLIDER MECHANISM ON THE ESTIMATION OF THE INSTANTANEOUS ENGINE FRICTION TORQUE

✍ Scribed by N.G. CHALHOUB; H. NEHME; N.A. HENEIN; W. BRYZIK

• Book ID: 102607300
• Publisher: Elsevier Science
• Year: 1999
• Tongue: English
• Weight: 208 KB
• Volume: 224
• Category: Article
• ISSN: 0022-460X
• DOI: 10.1006/jsvi.1999.2192

✦ Synopsis

The focus on the current study is to assess the e!ects of structural deformations of the crankshaft/connecting-rod/piston mechanism on the computation of the instantaneous engine friction torque. This study is performed in a fully controlled environment in order to isolate the e!ects of structural deformations from those of measurement errors or noise interference. Therefore, a detailed model, accounting for the rigid and #exible motions of the crank-slider mechanism and including engine component friction formulations, is considered in this study. The model is used as a test bed to generate the engine friction torque, ¹ D?

, and to predict the rigid and #exible motions of the system in response to the cylinder gas pressure. The torsional vibrations and the rigid body angular velocity of the crankshaft, as predicted by the detailed model of the crank-slider mechanism, are used along with the engine load torque and the cylinder gas pressure in the (P} ) method to estimate the engine friction torque, ¹ DC . This method is well suited for the purpose of this study because its formulation is based on the rigid body model of the crank-slider mechanism. The digital simulation results demonstrate that the exclusion of the structural deformations of the crank-slider mechanism from the formulation of the (P! ) method leads to an overestimation of the engine friction torque near the top-dead-center (TDC) position of the piston under "ring conditions. Moreover, for the remainder of the engine cycle, the estimated friction torque exhibits large oscillations and takes on positive numerical values as if it is inducing energy into the system. Thus, the adverse e!ects of structural deformations of the crank-slider mechanism on the estimation of the engine friction torque greatly di!er in their nature from one phase of the engine cycle to another.