Design Investigation of Linear Motor for Artificial Heart Driving

Abstract

The authors have been considering to use a linear pulse motor (LPM) as a driving source of a totally implantable artificial heart (TAH), and have developed a series of artificial heart models that incorporate such a motor. The newly developed linear-type TAH (linear TAH) has two blood pumps, which are inflated and deflated alternately by the LPM, causing a pusher plate to pulsate the blood.
This paper deals with the performance calculation of the LPM using the loading ratio. Then some motors manufactured for driving TAHs were selected to compare their machine parameters. The selected motors were LPMs, linear oscillatory actuator, brushless dc motors, and ultrasonic motor. Two parameters were selected for the comparison: the mechanical output/volume ratio and the motor constant. The results may be summarized as follows:
1. the LPM was designed based on the loading ratio, and the kinetic thrust and velocity were obtained at the range of 77 newtons, 80mm/s respectively;
2. the loading ratio of the LPMs were more than eight times larger in comparison with the rotary motors which were used in industrial machines;
3. the motor constants of the LPMs were recognized one figure larger than that of the bnrshless dc motors.
In order to reduce the volume of the linear TAN, it is necessary to increase the drive velocity of the LPMs. Application of the linear motor to a nonpulsatile artificial heart will be one way to achieve this.