FIGS. 8a, 8b, 8c, 8d and 8e are a perspective view showing a tank unit within the artificial heart driving apparatus, a horizontal sectional view of the tank unit, a sectional view taken along the like VIIIc--VIIIc in FIG. 8b, a partial enlarged sectional view showing the connection between a terminal and a tank, and a partial enlarged sectional view showing the connection between a pressure senso