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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 combustion simulation based on CFD (Computational Fluid Dynamics) was attempted in order to visualize in-cylinder combustion phenomena of a small displacement, high speed four-stroke SI engine for motorcycle applications. To verify the results of the simulation, the steady state flow in a cylinder, the fuel spray behavior and the flame propagation behavior in an actual engine were measured and compared. The results were that an adequate correlation was confirmed in each phenomenon, proving that the CFD was applicable as a means of visualization. As the result of the investigation of the combustion system applying this technique, improvements such as the specific fuel consumption and the extension of the lean combustion zone were attained, assuring effectiveness of this technique for actual engine development. This technique has been applied to the development of the world's first four-stroke 50cm3 PGM-FI (Programmed Fuel Injection) engine.

Lubricant contamination is a frequent hazard to bearing life in automotive transmissions. The “Sealed Clean” bearing concept uses dynamic, rubber seals to exclude significant contamination from transmission bearings. However there is often insufficient space in a roller bearing application to accommodate seals. HTF steel specifications and processing were developed for such applications. Debris within a rotating bearing will create indentations in the raceway. Contact stress is concentrated at the indentation edges and fatigue damage is accelerated. A indentation's diameter and edge radius determine the stress concentration between the ball and raceway. The HTF steel specification and tightly controlled heat treatment processing have been developed to provide long life despite the contamination hazard. Testing confirms the effectiveness of the new material.