System Estimation of Linear Pulse Motor-Driven Artificial Heart

The authors selected a linear pulse motor from among eight kinds of linear motors, because it had the highest thrust/input (N/W) ratio. This paper summarizes the calculated and experimental results of applying this linear pulse motor to an artificial heart drive. The configuration and drive control unit of a linear pulse motor (LPM) — driven total artificial heart are described and the life of a LPM is defined by calculation and experiment. The investigation revealed that the calculated LPM life was 137 days, but that the measured value was 32 days in the case of accelerated-life testing. Both values fall far short of the life required for a total artificial heart, i.e., 365 days (1 year). Calculation and experiment revealed that the major cause of the short life was the degradation of the linear bearings. The formula used to calculate the life indicates that reducing the vertical thrust currently achieves nearly 170 N, which is effective for improving linear bearing durability.