Research on Crankshaft System Behavior Based on Coupled Crankshaft-Block Analysis

Achieving a multi-cylinder engine with excellent noise/vibration character sties and low friction at the main bearings requires an optimal design not only for the crankshaft construction but also for the bearing support system of the cylinder block. To accomplish that, it is necessary to understand crankshaft system behavior and the bearing load distribution for each of the main bearings. Crankshaft system behavior has traditionally been evaluated experimentally because of the difficulty in performing calculations to predict resonance behavior over the entire engine speed range. A coupled crankshaft-block analysis method has been developed to calculate crankshaft system behavior by treating vibration and lubrication in a systematic manner. This method has the feature that the coupled behavior of the crankshaft and the cylinder block is analyzed by means of main bearing lubrication calculations. This paper presents the results obtained with this method. The main bearing loads were measured experimentally and compared with the calculated results. Both sets of data showed good agreement. It was also observed that the main bearing of the crankshaft-flywheel system. If was found that the influence on friction of crankshaft bending and variation in the clearance between the main beatings increased with decreasing engine speed and load. Good agreement was seen between the calculated results and experimental data for the resonant behavior of the crankshaft-flywheel system at high engine speeds. The main journal center orbit at the main bearing in the vicinity of the flywheel was affected by this vibration.