Multiple rotor, wide blade, axial flow pump

1. A blood pump, comprising:

a pump housing;

a plurality of rotors within said housing aligned along a common rotational axis;

each of said rotors having a plurality of discrete substantially axially directed flow channels which are spaced from each other and extend from one end of said rotor to the other end of said rotor, each of said flow channels having an approximate 90° offset along the axis of said rotor from an inlet entrance to an outlet exit;

each of said rotors having discrete non-channel portions intermediate said flow channels;

said flow channels being in a shape tending to drive blood in said channels through said housing in such axial direction when rotated;

said flow channels collectively having a total width at the radial periphery of the rotor that is equal to or substantially less than the collective total width of the non-channel portions of said rotor at said radial periphery; and

a motor comprising a plurality of magnetic poles carried by each of said rotors and a plurality of electromagnetic windings adjacent said magnetic poles for magnetic interaction therewith such that at least two of said rotors may be rotated in opposite directions.

2. The blood pump of claim 1 in which the overall width of said flow channels varies along their lengths.

3. The blood pump of claim 2 in which the flow channels are narrower at the inlet entrance to the flow channels than at the outlet exits from the flow channels.

4. The blood pump of claim 1 in which each of said rotors is axially spaced apart from each other rotor.

5. The blood pump of claim 4 in which said rotors are free of stationary blades positioned between them.

6. The blood pump of claim 1 in which each of said rotors is free to rotate at a different rate relative to each other rotor.

7. The blood pump of claim 1 in which more than two rotors are present and adjacent rotors rotate in opposite directions from each other.

8. The blood pump of claim 1 in which two rotors are present.

9. The blood pump of claim 1 comprising in addition at least one magnetic bearing system to maintain the axial position of each of said rotors within said housing.

10. The blood pump of claim 9 in which said at least one magnetic bearing system comprises permanent magnets mounted in said non-channel portion of each rotor, said motor is of a radial flux gap design type, and axially directed magnetic forces hold the rotor in position.

11. The blood pump of claim 1 in which the motor comprises at least one separate, hermetically sealed unit that slides over said pump housing into position and is secured thereto, said pump housing being tubular.

12. The blood pump of claim 11 in which said housing is cylindrical.

13. The blood pump of claim 1 in which said plurality of rotors positioned in said housing are positioned in series flow, for increased pumping pressure capacity.

14. The blood pump of claim 1 in which said non-channel portions of each rotor have substantially equal peripheral surface areas collectively defining a cylindrical periphery of the rotor; and

each of said peripheral surface areas comprises a first tapered surface adjacent an inlet entrance to a flow channel and a second tapered surface adjacent an outlet exit from said flow channel.

15. The blood pump of claim 14 in which each of said first and second tapered surfaces has an entrance portion defining a gap between said tapered surface and said housing, said gap being larger at said inlet entrance than at other portions of said tapered surfaces.

16. The blood pump of 1 in which each of said rotors comprises four of said flow channels.