The mechanism performance of improved oil pump with micro-structured vanes

The wear of oil pump vanes easily leads to the noise and vibration, even results the decrease of volume efficiency and total efficiency. In order to reduce the friction and improve the lubrication between the vane and the pump inner wall, the micro-machining of micro-structure on the oil pump vanes is proposed. First, the micro-V-grooves with the depth ranging from 500μm to 50μm were micro-grinding on the top of the vanes by a diamond grinding wheel. Secondly, the experiments were conducted to test the actual flow rate, the output power and the overall efficiency of the oil pump with and without the micro-groove vanes. Then, the computational fluid dynamics (CFD) method was adopted to simulate the pump internal flow field. Finally, the micro-flow field between the internal wall of the oil pump and the top of micro-grooved vanes was analyzed. The results shows that the pump overall efficiency increased as the decrease of micro-groove depth from 500 μm to 50μm and not be affected by the rotate speed and working frequency of the pump rotator. Especially the micro-groove with depth of 50μm, the actual flow rate, the output power and the overall efficiency reached to the maximum. From CFD simulation, the velocity of the micro-flow between the surfaces of the vane and inner wall was larger than the pump linear velocity when the microstructure depth is larger than 50μm, leading to an internal leakage. When the micro-groove depth is between10-50μm, the velocity of the micro-flow was less than the pump linear velocity and no internal leakage was found, but the oil film thickness is too small to be beneficial to lubrication according to the fluid dynamic characteristics. Thus, for the oil pump equipping with micro-grooved vane with the depth of 50 μm, the internal leakage not only is avoided but the lubrication efficiency is improved and the oil pump efficiency is also enhanced. (paper)