| Active liquid cooling technology is the mainstream way of heat dissipation in the future.For the liquid cooling system,micro pump is the most vulnerable part to failure.Therefore,the life and reliability of the micro pump determine the life and reliability of the whole system.Our laboratory developed a hydraulic suspension micro pump with a long theoretical service life and long theoretical reliability.However,the true service life and reliability of the hydraulic suspension micro pump are unknown and have not been proven,posing a huge obstacle to market application.Therefore,it is of great significance to carry out life test and reliability research on this hydraulic suspension micro pump.In this thesis,the accelerated life testing method was used to predict the service life of the hydraulic suspension micro pump.Meanwhile,the reliability problems found in the test process were studied and improved.The specific work and achievements are as follows:1)The fault tree analysis method was used to conclude and qualitatively analyze that the failure of the hydraulic suspension micropump was mainly caused by the failure of the radial dynamic sliding bearing and the impeller.The influence mechanism of three kinds of environmental stress on the reliability of hydraulic suspension micropump was analyzed,which provides a theoretical basis for the selection of acceleration stress in accelerated life testing;2)A set of accelerated life testing scheme for rotating hydraulic machinery such as the hydraulic suspension micro pump was designed and put forward.Meanwhile,a test bench was built and an accelerated life testing was carried out.The service life of the hydraulic suspension micro pump was calculated to be 68055 h under rated working conditions.At the same time,the reliability problems and weak links of the hydraulic suspension micro pump were found accurately through the test: the bearing capacity of the radial dynamic sliding bearing is insufficient,the rotor magnet is corroded and the impeller wear or fracture;3)The liquid film bearing capacity of the radial dynamic sliding bearing was calculated by numerical simulation method.The influence law of four important parameters on the liquid film bearing capacity of radial dynamic sliding bearing was analyzed.After the analysis,we found: increasing the bearing eccentricity,increasing the shaft speed,decreasing the viscosity of the fluid,increasing the width to diameter ratio can increase the bearing capacity,and can improve or avoid bearing scratch wear phenomenon,improve the suspension performance of the radial dynamic sliding bearing;4)The parameters of the radial dynamic sliding bearing of the hydraulic suspension micro pump were improved and a new prototype was manufactured.A laser displacement test system was designed and built to test the suspension performance of the radial dynamic sliding bearing of the hydraulic suspension micro pump before and after the improvement.After the test,we found: at the rotating speed of 20,000 rpm,the fluctuation range of the center of the rotor magnet of the improved bearing is 35μm,which decreased by 35.2% compared with that before the improvement,indicating that the suspension performance of the improved radial dynamic sliding bearing has been significantly improved. |
