Axial flow blood pump
The invention generally relates to improved medical blood pump devices, systems, and methods. For example, blood pumps may be provided that include a housing defining a blood flow path between an inlet and an outlet. A rotor may be positioned in the blood flow path. A motor stator may be driven to rotate the rotor to provide the blood flow through the pump. Axial and/or tilt stabilization components may be provided to increase an axial and/or tilt stabilization of the rotor within the blood flow path. In some embodiments, biasing forces are provided that urge the rotor toward a bearing component. The biasing force may be provided by adjusting drive signals of the motor stator. Additionally, or alternatively, one or more magnets (e.g., permanent/stator magnets) may be provided to bias the rotor in the upstream and/or downstream direction (e.g., toward a bearing (chamfer, step, conical), or the like).
1. An axial flow mechanical circulatory support system, comprising:
a housing with an internal wall defining a flow path extending along an axis, an inlet upstream along the axis and an outlet downstream from the inlet along the axis;
an impeller positioned within a housing flow path, the impeller comprising a magnetic member and blades for pumping blood in a flow direction from the inlet to the outlet when the impeller rotates about an axis of rotation;
a stator positioned about the impeller for generating a magnetic field to rotate the impeller;
a bearing for stabilizing the impeller in an axial direction, the bearing comprising:
a bearing member for applying a bearing force against the impeller in a first axial direction, wherein the first axial direction is along the flow direction from the inlet towards the outlet; and
a biasing magnetic source for applying a biasing force configured to urge the impeller in a second axial direction opposite the first axial direction and opposite the flow direction from the inlet towards the outlet, wherein the biasing force comprises an attractive force between the biasing magnetic source and the impeller.
2. The axial flow mechanical circulatory support system of claim 1 , wherein the biasing force is greater than the bearing force when the impeller is at rest such that the impeller rests against the bearing member when at rest.
3. The axial flow mechanical circulatory support system of claim 1 , wherein the biasing magnetic source applies a passive biasing force.
4. The axial flow mechanical circulatory support system of claim 1 , wherein the bearing member applies a passive bearing force.
5. The axial flow mechanical circulatory support system of claim 1 , wherein the biasing force is only applied when the impeller is rotating.
6. The axial flow mechanical circulatory support system of claim 1 , wherein the stator forms a passive magnetic bearing by modifying a drive signal to apply the biasing force on the impeller.
7. The axial flow mechanical circulatory support system of claim 1 , wherein the bearing member comprises a chamfer bearing.
8. The axial flow mechanical circulatory support system of claim 1 , wherein the bearing member comprises a step bearing.
9. The axial flow mechanical circulatory support system of claim 1 , wherein the bearing member comprises one or more magnets around the impeller upstream of an axial center of the impeller.
10. The axial flow mechanical circulatory support system of claim 1 , wherein the biasing magnetic source applies a substantially constant axial force.
11. The axial flow mechanical circulatory support system of claim 1 , wherein the impeller is formed of a magnetic body.
12. The axial flow mechanical circulatory support system of claim 1 , wherein the inlet and the outlet are axially aligned.
13. The axial flow mechanical circulatory support system of claim 1 , wherein the biasing magnetic source comprises one or more magnets upstream and downstream of a center of the impeller.
14. The axial flow mechanical circulatory support system of claim 1 , wherein the biasing magnetic source comprises one or more magnets configured to be actively controlled to adjust the biasing force when a gap between the bearing member and a rotor changes.
15. The axial flow mechanical circulatory support system of claim 1 , wherein the biasing magnetic source comprises one or more magnets configured to be actively controlled to adjust the biasing force when an impeller speed changes.
16. The axial flow mechanical circulatory support system of claim 15 , wherein the biasing force is adjusted by adjusting a distance between the one or more magnets and the impeller.