Axial flow rotor with downstream bearing wash flow
An implantable blood pump includes an impeller rotatable about a rotational axis, having a body with a bottom surface at a downstream end and a central opening centered about the axis extending at least partially through the body from the bottom surface. A projecting element, e.g., a shaft, extends from below the bottom surface into or through the opening to support the impeller. The body can be configured to drive a primary downstream blood flow along an exterior of the body to beyond a peripheral edge of the bottom surface, and to provide a secondary downstream blood flow through the opening and along the bottom surface to beyond the peripheral edge, the secondary flow improving washing of a bearing surface.
1. An impeller for a blood pump, comprising:
a ferromagnetic body having a bottom surface at a downstream end of the body and a central opening extending at least partially through the body from the bottom surface, the central opening centered about a rotational axis of the body, the rotational axis defining an axial direction; and
the body configured to rotate about an element projecting from a surface below the bottom surface into the central opening to drive a primary blood flow along an exterior of the body to beyond a peripheral edge of the bottom surface, and the body configured to drive a secondary blood flow through the central opening toward the bottom surface and then outwardly along the bottom surface to beyond the peripheral edge, the body including a bearing proximate a distal end of the element, the bottom surface undulates in a direction of a circumference of the bottom surface between troughs and respective elevations, the troughs and elevations of the bottom surface are configured to drive the secondary flow of the fluid towards the peripheral edge of the bottom surface.
2. The impeller of claim 1 , wherein the undulations of the body define a plurality of ridges protruding in an axial direction below portions of the bottom surface, the ridges defining a plurality of fluid channels for driving the secondary flow between the opening and the peripheral edge.
3. The impeller of claim 2 , wherein the ridges are blades elongated in a direction from the opening towards the peripheral edge.
4. The impeller of claim 3 , wherein the fluid channels have arcuate shape.
5. The impeller of claim 3 , wherein the ridges have straight walls defining the plurality of fluid channels.
6. The impeller of claim 5 , wherein the ridges taper in a direction from the peripheral edge towards the opening.
7. The impeller of claim 6 , wherein the walls of each fluid channel are parallel.
8. The impeller of claim 7 , wherein each fluid channel extends in a radial direction from the opening to the peripheral edge.
9. The impeller of claim 1 , wherein the impeller includes blades projecting from the exterior of the body for driving the primary flow.
10. An implantable blood pump, comprising:
a ferromagnetic impeller body having a bottom surface at a downstream end of the body and a central opening extending at least partially through the body from the bottom surface, the central opening centered about a rotational axis of the body, the rotational axis defining an axial direction;
the body being configured to rotate about an element projecting from below the bottom surface into the central opening to drive a primary downstream blood flow along an exterior of the body to beyond a peripheral edge of the bottom surface and axially downstream from the impeller, the body including a bearing proximate a distal end of the element; the body configured to drive a secondary downstream blood flow through the central opening toward the bottom surface and then outwardly along the bottom surface to beyond the peripheral edge, the bottom surface include a plurality of axially protruding ridges defining at least one fluid channel, the plurality of axially protruding ridges being configured to drive the secondary downstream blood flow from the opening towards the peripheral edge; and
the pump being configured to rotate the body about the axis and to drive the blood in a generally axial direction downstream from the impeller.
11. The pump of claim 10 , wherein each one of the plurality of axially protruding ridges is a blade elongated in a direction from the opening towards the peripheral edge, and the plurality of fluid channels have an arcuate shape.
12. The pump of claim 10 , wherein each one of the plurality of axially protruding ridge has straight walls defining the at least one fluid channel, the straight walls extending in a radial direction from the opening to the peripheral edge.
13. The pump of claim 10 , wherein the impeller comprises blades projecting from the exterior of the body for driving the primary flow.
14. The pump of claim 10 , wherein the body comprises a plurality of magnetic poles proximate the bottom surface, the body being configured to be rotationally driven by and the axial position of the body being secured by an external rotating magnetic field.