REDUCTION OF SHAFT VIBRATION BY PRESSURE CONTROL OF EXTERNALLY PRESSURIZED GAS JOURNAL BEARINGS WITH ASYMMETRIC GAS SUPPLY (EXPERIMENTS OF SINGLE DIRECTION CONTROL)

Externally pressurized gas journal bearings can contactlessly support shafts by gas pressure. This provides advantages such as high precision rotation, low frictional loss, and high rotational speeds. However, the load capacity of gas bearings is very small compared to mechanical rolling contact bearings, so they are mainly applied to small size rotating machinery. In order to support larger load shaft loads, we have developed an externally pressurized gas journal bearing with an symmetric gas supply. With this bearing, high and low pressure gases are supplied to the loading and to the counter-loading side bearing surfaces, respectively. This mechanism provides a large load capacity and small gas flow rate compared with conventional gas journal bearings. In this research, we made the test bearing and a rig for our experiments. In order to verify the availability of the bearing, a program to control pressure was created to conduct the test. Pressurized gas was supplied to the test bearing by feed forward control. In this study, single direction control test was carried out. The test results showed that the shaft amplitude decreases compared with a conventional bearing. The availability of the proposed bearing characteristics are verified.