Impeller suspension mechanism for heart pump

Abstract

A centrifugal blood pump includes a housing that defines an inlet passage, a chamber, and an outlet passage. The pump includes an impeller rotatably positioned in the chamber to transfer blood from the inlet passage through the chamber and to the outlet passage and magnetic members embedded in the impeller such that the impeller and the magnetic members rotate together within the chamber. The pump includes a motor to control movement of the impeller in the chamber. The motor is adjacent the chamber and separated from the chamber by a partition member. The pump includes an inner annular magnetic member and an outer annular magnetic member embedded in a side of the housing opposite the partition member. A first net magnetic force between the inner annular magnetic member and the magnetic members exhibits greater attraction than a second net magnetic force between the outer annular member and the magnetic members.

1 . A blood pump comprising:
 an impeller disposed within a housing, wherein the impeller comprises an inner magnet and an outer magnet relative to an axis of the impeller; and   an inner annular magnetic member and an outer annular magnetic member disposed in a wall of the housing relative to the axis of the impeller, wherein:
 the inner annular magnetic member attracts the inner magnet; 
 the outer annular magnetic member repels the outer magnet; and 
 the outer annular magnetic member extends radially beyond the outer magnet. 
   
     
     
         2 . The blood pump of  claim 1 , wherein:
 a distance between the outer magnet and the outer annular magnetic member is greater than a distance between the inner magnet and the inner annular magnetic member.   
     
     
         3 . The blood pump of  claim 1 , wherein:
 the inner annular magnetic member produces a greater magnetic force than the outer annular magnetic member.   
     
     
         4 . (canceled) 
     
     
         5 . The blood pump of  claim 1 , wherein:
 at least a portion of the inner annular magnetic member extends radially inward of the inner magnet.   
     
     
         6 . The blood pump of  claim 1 , further comprising:
 a ferromagnetic ring disposed between the inner annular magnetic member and the inner magnet.   
     
     
         7 . (canceled) 
     
     
         8 . The blood pump of  claim 1 , wherein:
 at least one of the inner annular magnetic member or the outer annular magnetic member comprises an electromagnet.   
     
     
         9 . A blood pump comprising:
 an impeller disposed within a housing, wherein the impeller comprises a plurality of magnets; and   at least one annular magnetic member disposed in a wall of the housing, wherein:
 the at least one annular magnetic member attracts a first portion of the plurality of magnets proximate to an axis of the impeller; 
 the at least one annular magnetic member repels a second portion of the plurality of magnets distal to the axis of the impeller; and 
 the at least one annular magnetic member extends radially beyond the plurality of magnets. 
   
     
     
         10 . The blood pump of  claim 9 , wherein:
 the plurality of magnets comprises an inner magnet and an outer magnet relative to an axis of the impeller.   
     
     
         11 . (canceled) 
     
     
         12 . The blood pump of  claim 9 , wherein:
 the at least one annular magnetic member comprises an inner annular magnetic member and an outer annular magnetic member relative to an axis of the impeller.   
     
     
         13 . The blood pump of  claim 9 , wherein:
 at least a portion of the at least one annular magnetic member extends radially beyond the plurality of magnets.   
     
     
         14 . The blood pump of  claim 9 , wherein:
 at least a portion of the at least one annular magnetic member extends radially inward of the plurality of magnets.   
     
     
         15 . The blood pump of  claim 9 , further comprising:
 a ferromagnetic ring disposed between the at least one annular magnetic member and the plurality of magnets.   
     
     
         16 . A blood pump comprising:
 an impeller disposed within a housing, wherein the impeller comprises a inner portion and an outer portion relative to an axis of the impeller; and   at least one annular magnetic member disposed in a wall of the housing, wherein:
 the at least one annular magnetic member attracts the inner portion of the impeller; 
 the at least one annular magnetic member repels the outer portion of the impeller; and 
 the at least one annular magnetic member extends radially beyond an outermost magnet of a plurality of magnets within the impeller. 
   
     
     
         17 . The blood pump of  claim 16 , wherein:
 the inner portion of the impeller comprises an inner magnet.   
     
     
         18 . The blood pump of  claim 17 , wherein:
 at least a portion of the at least one annular magnetic member extends radially inward of the inner magnet.   
     
     
         19 . (canceled) 
     
     
         20 . The blood pump of  claim 16 , further comprising:
 a ferromagnetic ring disposed between the at least one annular magnetic member and the impeller.   
     
     
         21 . The blood pump of  claim 9 , wherein:
 the at least one annular magnetic member comprises an inner annular magnetic member and an outer annular magnetic member relative to the axis of the impeller; and   a distance between the second portion of the plurality of magnets and the outer annular magnetic member is greater than a distance between the first portion of the plurality of magnets and the inner annular magnetic member.   
     
     
         22 . The blood pump of  claim 9 , wherein:
 the at least one annular magnetic member comprises an inner annular magnetic member and an outer annular magnetic member relative to the axis of the impeller;   the inner annular magnetic member produces a greater magnetic force than the outer annular magnetic member.   
     
     
         23 . The blood pump of  claim 9 , wherein:
 the at least one annular magnetic member comprises an electromagnet.   
     
     
         24 . The blood pump of  claim 16 , wherein:
 the at least one annular magnetic member comprises an inner annular magnetic member and an outer annular magnetic member relative to the axis of the impeller; and   a distance between the second portion of the plurality of magnets and the outer annular magnetic member is greater than a distance between the first portion of the plurality of magnets and the inner annular magnetic member.   
     
     
         25 . The blood pump of  claim 16 , wherein:
 the at least one annular magnetic member comprises an inner annular magnetic member and an outer annular magnetic member relative to the axis of the impeller;   the inner annular magnetic member produces a greater magnetic force than the outer annular magnetic member.