Pump arrangements for pumping fluid
A pump comprising a housing and a rotor rotatably accommodated in the housing and having an axis of rotation. The housing comprises a resilient seal member, an inlet and an outlet for fluid. The rotor comprises first and second surface areas, and the rotor and housing are cooperatively configured such that the second surface area is radially recessed from the first surface area, forming a chamber with an interior surface of the housing, and the first surface area seals against the interior surface. The seal member is located azimuthally between the outlet and the inlet. The seal member will engage the first and second surface areas, operative to prevent the passage of fluid from the outlet to the inlet as the rotor rotates. An edge of the seal member is coterminous with an aperture through which the fluid can flow.
1. A pump comprising:
a housing and
a rotor rotatably accommodated in the housing and having a longitudinal axis of rotation;
the housing comprising:
a resilient seal member,
an inlet and
an outlet for fluid;
the rotor comprising first and second surface areas;
the rotor and housing cooperatively configured such that the second surface area is radially recessed from the first surface area, a second surface and an interior surface of the housing defining a chamber,
the first surface area having a sealing engagement against the interior surface to contain the fluid within the chamber;
the seal member is located azimuthally between the outlet and the inlet; the seal member sized and shaped to engage the first and second surface areas as the rotor rotates about the longitudinal axis of rotation to prevent the passage of fluid from the outlet to the inlet;
wherein an unattached edge of the seal member defines an aperture with the housing.
2. The pump as claimed in claim 1 , wherein the seal member comprises a diaphragm having a rotor-facing surface, and an under-surface opposite the rotor-facing surface; the unattached edge connecting the rotor-facing surface and the under-surface.
3. The pump as claimed in claim 1 , wherein the aperture is substantially circular or square, or shaped as a substantially rectangular slot.
4. The pump as claimed in claim 1 , wherein the unattached edge connects opposite ends of the seal member.
5. The pump as claimed in claim 1 , wherein the aperture extends azimuthally over an aperture width, and the seal member extends azimuthally over a seal width, wherein the aperture width is less than the seal width.
6. The pump as claimed in claim 1 , wherein the seal member is configured such that at least a section of the unattached edge can travel through a greater radial distance than any other part of the seal member in response to the seal member being flexed as the rotor rotates through a full revolution.
7. The pump as claimed in claim 1 , wherein at least a section of the unattached edge travels the radial distance from the outermost radius of the first surface area to the innermost radius of the second surface area of the rotor as the rotor rotates.
8. The pump as claimed in claim 1 , wherein the housing is configured such that the fluid is expelled from the chamber through the aperture to the outlet.
9. The pump as claimed in claim 1 , wherein the seal member is formed in one piece with the housing, the seal member and the housing comprising the same material.
10. The pump as claimed in claim 1 , wherein the entire aperture is defined by the edge of the seal member.
11. The pump as claimed in claim 1 , wherein the seal member comprises elastomer material.
12. The pump as claimed in claim 1 , wherein the seal member has a mean radial thickness of from 0.1 to 3.0 mm.
13. The pump as claimed in claim 1 , wherein the seal member comprises an under-surface opposite a surface of the seal member contacted by the rotor, and the housing and pump are configured such that a second fluid contacts the under-surface to urge the seal member against the rotor.
14. The pump as claimed in claim 1 , comprising a resilient biasing member configured to urge the seal member against the rotor, wherein the resilient biasing member comprises a fluid-tight bulkhead to prevent the outlet from being in fluid communication with the under-surface of the seal member, and is configured to force fluid in the outlet towards the inlet between the seal member and the rotor if the pressure of the fluid in the outlet exceeds a contact pressure maintained by the resilient biasing member.
15. The pump as claimed in claim 1 , comprising a resilient biasing member configured to urge the seal member against the rotor; wherein the resilient biasing member and the seal member are configured such that the resilient biasing member variably flexes the seal member in response to the rotation of the rotor, and at least a section of the unattached edge remains adjacent the surface of the rotor as it rotates through a full revolution.
16. The pump as claimed in claim 1 ,
wherein the seal member comprises:
a diaphragm having a rotor-facing surface configured to engage; and
an under-surface opposite the rotor-facing surface;
wherein the unattached edge places the rotor-facing surface and the under-surface in fluid flow communication.