This report is described the study on the measurement of the oil film thickness between shaft and bearing in porous sintered oilless bearing as a DC spindle motor’s bearing system by using ultrasonic wave. Generally, the thickness of oil film generated between shaft and bearing is so thin that the direct measurement of its thickness is very difficult. Therefore, in this study, the ultrasonic method is proposed to measure the oil film thickness for the establishment of quantitative measuring. As a basic experiment, immersion ultrasonic technique is applied. Moreover, it is confirmed experimentally that there are approximately proportional relationship between the oil film thickness and the echo ratio of reflected ultrasonic amplitude. However, by the generation of heat at oil film under shaft rotating condition, the temperature of oil film and bearing are raised, and the measurement of the oil film thickness might become difficult because these acoustic properties are changed. Then, in this report, it is proposed to examine for the improvement in measuring accuracy with thermal correction system.

Tamura has been developing the bio-methane recirculation generating system by the technology as called GET system. This system is the bio-methane generation system from sustainable energy resources in fallow paddy fields and rice straw. In the varying environmental conditions, a conventional small gas engine could not be adapted. We try to develop a better control law for the electric governor of small engine by Model-Based Development method. We show the results of comparing the performance of control laws designed by MBD and MFD in simulation and experiment.