Rotor stability of a rotary pump

Abstract

A rotary pump including an impeller rotatable within a housing. A load is imposed on the impeller as it rotates, in a direction that is substantially parallel to the axis of rotation and wherein the load stabilises the motion of the impeller. The load may be achieved by magnetically biasing the impeller.

1 . A rotary pump including an impeller rotatable within a housing; wherein a load is imposed on said impeller as it rotates, in a direction that is substantially parallel to the axis of rotation and wherein said load stabilises the motion of the impeller.  
     
     
         2 . The rotary pump as claimed in  claim 1 , wherein said load is achieved by magnetically biasing said impeller.  
     
     
         3 . The rotary pump as claimed in  claim 2 , wherein said pump includes a set of stators positioned below the impeller and said set of stators generates said load.  
     
     
         4 . The rotary pump as claimed in  claim 2 , wherein magnetically biasing said impeller is achieved by at least one yoke.  
     
     
         5 . The rotary pump as claimed in  claim 1 , wherein an angle formed between the upper and/or lower axial surfaces of the impeller are not parallel with the respective corresponding surface of the inner wall of the housing.  
     
     
         6 . The rotary pump as claimed in  claim 1 , wherein said impeller is not circular and the inner walls of the housing are generally circular.  
     
     
         7 . The rotary pump as claimed in  claim 1 , wherein said load prevents or limits the impeller from contacting the housing, when in use.  
     
     
         8 . The rotary pump as claimed in  claim 6 , wherein said impeller is generally square shaped.  
     
     
         9 . The rotary pump as claimed in  claim 1 , wherein said impeller includes a hydrodynamic bearing.  
     
     
         10 . The rotary pump as claimed in  claim 8 , wherein said hydrodynamic bearing is formed by a taper on the surface of the impeller of between 10 μm and 50 μm.  
     
     
         11 . The rotary pump as claimed in  claim 1 , wherein a gap of less than 250 μm is formed between the impeller and the housing, when in use.  
     
     
         12 . A rotary pump as claimed in  claim 1 , wherein said pump is for pumping blood.  
     
     
         13 . A rotary pump as claimed in  claim 13 , wherein said pump is implantable within the body of a patient.  
     
     
         14 . A rotary pump including an impeller rotatable within a housing; wherein impeller is hydrodynamically suspended and wherein an angle formed between the upper and/or lower axial surfaces of the impeller are not parallel with the respective corresponding surface of the inner wall of the housing.