2203 MEMS 技術を用いたマイクロターボ機械 MEMS-BASED TURBO MACHINERY

This paper describes the design, fabrication and test of a MEMS-based micro turbo machinery. In this device, a compressor and a turbine are formed on the same side of the rotor to escape miss-alignment during bonding process. The rotor is supported by hydrostatic journal and thrust bearings. The device rotated only at low rotation speed up to 2500 rpm, and the rotation speed did not remarkably changed by adjusting air supplies to the hydrostatic bearings. From the test results, we found important problems to be solved for high speed rotation. Concerning to fabrication, flat and smooth bearing surfaces is difficult to fabricate, and a bearing gap is difficult to precisely control due to spikes on etched surfaces and the warp of the devices induced by anodic bonding. The other concerning is bearing design. The journal bearing has a very low L/D number(length divided by diameter). As a result, the journal bearing has a small journal surface, and it is difficult to install the restriction on the journal bearing. Additionally, there is interference between the journal and thrust bearing due to air leakage.