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Using a 1D simulation that transforms the 3D shape of intake-exhaust systems into one dimension and calculates the thermodynamics and fluid gas dynamics of internal combustion engines, a prediction technology of the output power and intake-exhaust noise for small- displacement single-cylinder motorcycles was established. Output power can be calculated accurately for various engines with different displacements and cooling systems by adjusting the boundary conditions in the calculation model. The intake-exhaust noise can be calculated accurately by clarifying some important points for accuracy when transforming the 3D shapes of the intake-exhaust system into the 1D model and by reflecting them in the calculation model. As for mufflers that have complicated internal structures, the calculation of exhaust-noise cannot be made with sufficient accuracy because 1D simulation does not calculate spatial flow behavior. But, improvement of accuracy is expected using a 1D-3D coupled simulation.

This paper investigates and describes the fatigue mechanism in bearings for automotive alternators. We have analyzed the peculiar microstructure change found in these bearings. We have also investigated the effects of grease properties, vibration, and elastic deformation of the outer ring. By analyzing the bearings used in actual engine tests and grease tests for fundamental characteristics, we were able to conclude that the fatigue causes were two-fold: load amplification caused by resonance and high bending stresses caused by elastic deformation of the outer ring. As a practical result, we were able to adopt a newly formulated grease which decreased the vibration level and the peak rolling element load. This led to the development of longer life bearings for automotive alternators.

The conventional rolling bearing life equation (1), which is based on the theory of Lundberg and Palmgren, has a problem in that it does not match the actual bearing life in all operating conditions. For instance, while the actual life of a bearing under clean lubrication is 20 times longer than the calculated life, actual life under contaminated lubrication is as low as one-tenth of the calculated life. To solve this problem, the following life equation (Eq. 1: Advanced Bearing Life Equation) was developed with the aNSK life modification factor: The new aNSK factor is based on data from bearing life aNSK tests involving over 450 roller bearings and over 550 ball bearings under a variety of operating conditions. The new life equation with the aNSK factor showed a satisfactory fit between calculated life and actual life.