Abstract: A linear actuator includes permanent magnet annuli arranged about an armature core for axial movement in a tubular stator upon energization of coils arranged in concentric association with the armature. The stator has portions extending radially inwards of the coils and towards one another beneath each coil, which define a spacing between the coil and the armature. The annuli have a substantially radially magnetized structure and the coils are configured for single phase power input. In one embodiment (FIG. 6), two pairs of spaced annuli are arranged on the core, wherein the axial length of the outermost annuli is half the axial length of the inner annuli.

Abstract: In an electromagnetic driver according to the invention, electromagnetic units are arranged in the axial direction of a shaft, and a power supply change-over device is so formed that, when an attractive magnetic field arises between the coil unit and the magnetic unit of the one of the electromagnetic units, a repulsive magnetic field is generated between the coil unit and the magnet unit of the other of the electromagnetic units. As the polarity is alternately changed over by the power supply change-over device when a direct current is supplied to the exciting coils of the electromagnetic units, the coil unit or the magnetic unit reciprocates, and further the shaft reciprocates in the axial direction.

Abstract: In one embodiment described in the specification, a surgically implantable reciprocating pump employs a check valve as the piston, which is driven by a permanent magnet linear electric motor to assist either side of the natural heart. The pump is implanted in the aorta or pulmonary artery using vascular attachment cuffs such as flexible cuffs for suturing at each end with the pump output directly in line with the artery. The pump is powered by surgically implanted rechargeable batteries. In another embodiment, pairs of pumps are provided to replace or assist the natural heart or to provide temporary blood flow throughout the body, for example, during operations to correct problems with the natural heart.

Abstract: A driven paramagnetic member, located between two stationary magnetic members, is moved in opposite directions by alternately energizing intermediate magnets which are located between the stationary members and the driven member. To conserve electrical energy, the ampere-turns of the intermediate magnets are reduced gradually while the members are moving together to reduce the gap thicknesses therebetween.