永磁减载耐久性叶轮血泵的研制

The Development of Durable Impeller Blood Pumpwith Novel Permanent Magnetic Bearing for Load Reduction

为了延长血泵使用寿命 ,目前除了电磁磁浮还没有更好的解决办法 ,但是电磁磁浮需要位置检测和反馈控制 ,而且增加能耗、可靠性差 ,因此提出了永磁减载的新方法。介绍了一种新颖的永磁轴承 ,它具有径向支承和轴向弹簧的双重作用。在血泵驱动电机的两端安装两个永磁轴承 ,既可以为转子提供径向减载 ,又可以使转子轴向悬浮。为了减小定子与转子之间的摩擦 ,除了提高轴承的径向支承力以外 ,还要减小定子铁心对转子磁钢的径向吸引力 ,解决的办法是适当减小铁心和转子磁钢的用量 ,同时增大定子与转子间的气隙。通过实验研究转子磁钢参数和气隙的变化对电机效率的影响 ,可以确定转子磁钢的尺寸和气隙值 ,从而使电机保持高效率运转 ,同时又实现了永磁减载。通过永磁减载方法设计的耐久性叶轮血泵已连续稳定运转八个月 ,振动小 ,噪音低 。

The ideal to achieve durability of impeller blood pump through passive load reduction was put forward and brought into reality. It was achieved by using a special magnetic bearing, which functions both like a bearing, radially, and like a spring, axially. Its radial repulsive force was used to counteract the attractive force between the motor iron core and the rotor magnets, and its axial resilient force was used to achieve axial suspension of the rotor. The effect of load reduction could be enhanced by enlarging the air gap between the magnets and the iron core, while reducing the volume of rotor magnets and the length of iron core. In order to retain high efficiency of the device, experimental research was carried out to identify the minimum volume of magnets and the maximum value of air gap for pump performance. Based on the above analysis, a durable impeller blood pump through passive load reduction was developed in our lab. The endurance test has been on going for about 8 months with the vibration and noise greatly reduced. This novel device can replace the other available blood pumps which are devised with mechanical bearings or electromagnetic bearings.