Qian K X, Zeng P, Ru W M, Yuan H Y
Institute of Biomedical Engineering, Jiangsu University, Xue-fu Road 310, Zhenjiang, Jiangsu 212013, China.
Med Eng Phys. 2006 May;28(4):383-8. doi: 10.1016/j.medengphy.2005.07.007. Epub 2005 Sep 23.
According to tradition, permanent maglev cannot achieve stable equilibrium. The authors have developed, to the contrary, two stable permanent maglev impeller blood pumps. The first pump is an axially driven uni-ventricular assist pump, in which the rotor with impeller is radially supported by two passive magnetic bearings, but has one point contact with the stator axially at standstill. As the pump raises its rotating speed, the increasing hydrodynamic force of fluid acting on the impeller will make the rotor taking off from contacting point and disaffiliate from the stator. Then the rotor becomes fully suspended. The second pump is a radially driven bi-ventricular assist pump, i.e., an impeller total artificial heart. Its rotor with two impellers on both ends is supported by two passive magnetic bearings, which counteract the attractive force between rotor magnets and stator coil iron core. The rotor is affiliated to the stator radially at standstill and becomes levitated during rotation. Therefore, the rotor keeps concentric with stator during rotation but eccentric at standstill, as is confirmed by rotor position detection with Honeywell sensors. It concludes that the permanent maglev needs action of a non-magnetic force to achieve stability but a rotating magnetic levitator with high speed and large inertia can maintain its stability merely with passive magnetic bearings.
按照传统观点，永磁悬浮无法实现稳定平衡。然而，作者研发出了两款稳定的永磁悬浮叶轮血泵。第一款泵是轴向驱动的单心室辅助泵，其中带有叶轮的转子由两个被动磁轴承径向支撑，但在静止时轴向与定子有一个点接触。随着泵转速升高，作用在叶轮上的流体动力增加，会使转子从接触点脱离并与定子分离。然后转子完全悬浮。第二款泵是径向驱动的双心室辅助泵，即叶轮式全人工心脏。其两端带有两个叶轮的转子由两个被动磁轴承支撑，这两个磁轴承抵消了转子磁体与定子线圈铁芯之间的吸引力。转子在静止时径向与定子相连，旋转时悬浮。因此，通过霍尼韦尔传感器进行的转子位置检测证实，转子在旋转时与定子保持同心，但在静止时偏心。得出的结论是，永磁悬浮需要非磁力作用来实现稳定，而高速大惯量的旋转磁悬浮仅靠被动磁轴承就能维持其稳定性。
