| 摘要: | 研究期間：10108~10207;In order to conform to the requests of small-form-factor data storage drives and energy efficiency, the spindle motor requires stability, miniaturization, high rotational speed and low energetic consumption. For the spindle motor, the bearing is the most crucial component. However, the spindle motors using conventional sleeve bearings or ball bearings have reached the technical limit nowadays. Instead of sleeve bearing or ball bearing, the hydrodynamic journal bearings have emerged as an ideal solution for next-generation data storage drives characterized by requirements for low noise, low friction and an extended service life. It has been shown that the stiffness of hydrodynamic journal bearings can be improved via etching the surface of a hydrodynamic journal bearing with a herringbone-grooved pattern (HGJB), which spreads shock loads over the entire bearing area and therefore enhances the mechanical damping of the motor system. During operation, the herringbone grooves pump the lubricant in the inward direction, i.e. toward the center of the bearing. Therefore the herringbone grooves increase the pressure within the journal, and improve the bearing performances. In addition, the herringbone groove in a HGJB plays a crucial role in smoothing the pressure distribution within the bearing system. Thus, its design has a direct effect upon the load capacity of the bearing and its service life, shock resistance, and noise characteristics. Accordingly, the literature contains various investigations into the correlation between the load capacity of the conventional HGJB and the groove pattern parameters (i.e. the number of grooves, the groove width ratio, the groove depth ratio, the groove angle, the groove width, the groove depth, and the groove length) or the operating conditions (i.e. the eccentricity ratio, the rotational speed, the bearing clearance, and so on). However, the conventional HGJB has three chief drawbacks. One is that the structure of the herringbone grooves in a conventional HGJB has been claimed in patents, thus it has its use limit. Another is that the load capacity of the conventional HGJB decreases with decreasing dimension of the bearing, thus the spindle stiffness could be insufficient for miniaturized conventional HGJB. A third is that most studies in the past employed straight-line HGJB to improve their performance. However, very few studies has analyzed numerically or experimentally the improved effects of curved grooves. In order to overcome these drawbacks, this project will develop a newly designed curve-grooved multi-step journal bearing (CGMSJB) for data storage device applications. We aim to improve the load capacity and provide greater spindle stiffness by multi-step grooves with each groove comprising curved-grooved profile. The multi-step hydrodynamic grooves are designed in such a way as to fully utilize the limited surface area of the bearing and provide a total of multi-regions of peak pressure during its rotation, and therefore provide a more uniform support force than that provided by a conventional HGJB. Another advantage of the proposed CGMSJB is that the side leakage can be reduced due to the multi-turn structures of multi-step grooves and they can improve the stability and lifetime of the bearing. This project will utilize self-developed numerical analysis software to optimize the design parameters of the proposed CGMSJB. The performances of the proposed CGMSJB will be then investigated experimentally using a laboratory-built prototype spindle motor. We anticipate that the proposed CGMSJB will represent a suitable solution for both existing and emerging portable data storage applications. |
