Abstract: Magnetic bearing has no mechanical contact between the rotor and stator, and a rotary pump with magnetic bearing has therefore no mechanical wear and thrombosis. The available magnetic bearings, however, are devised with electric magnets, need complicated control and remarkable energy consumption. Consequently, it is difficult to apply an electric magnetic bearing to rotary pump, without affecting its simplicity, implantability and reliability. The author has developed a levitated impeller pump merely with permanent magnets. The rotor is supported by permanent magnetic forces radially. On one side of the rotor, the impeller is fixed; and on the other side of the rotor, the rotor magnets are mounted. Opposite to this rotor magnets, a driving magnets is fastened on the motor axis. Thereafter, the motor drives the rotor via magnetic coupling. In laboratory tests with saline, in case the rotor keeps still or rotates under 4 000 r/min, the rotor magnets have one-point contact axially with a spacer between the rotor magnets and the driving magnets. The contacting point is located in the center of the rotor. As the rotating speed increases gradually to over 4 000 r/min, the rotor will disaffiliate from the stator axially. Then the rotor will be fully levitated. Since the axial levitation is produced by hydraulic force and the rotor magnets have a gyro-effect, the rotor rotates very stably during levitation. As a left ventricular assist device, the pump works in a rotating speed range of 5 000~8 000 r/min, and the levitation of the impeller, hence, is assured by the practical use of the pump. The permanent maglev impeller pump retains the advantages of rotary pump but overcomes the disadvantages of the levitated pump with electric magnetic-bearing, and has actually met most of requirements of artificial heart blood pump, thus promises to be able to replace the donor heart for transplantation and to support the failing heart permanently.

Key words: Blood pump, Centrifugal pump, Gyro-effect, Magnetic bearing, 3-RPR, Inchworm locomotion, Over-constrainted, Serial-parallel mechanism