Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Turbine regenerative pump
Reexamination Certificate
1999-10-08
2001-04-03
Look, Edward K. (Department: 3745)
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Turbine regenerative pump
C416S23600R
Reexamination Certificate
active
06210102
ABSTRACT:
BACKGROUND OF THE INVENTION
1) Field of the Invention
This invention relates generally to pumps, and in particular to a regenerative fuel pump having a vaned impeller. Such a pump is useful as an electric-motor-operated fuel pump for an automotive vehicle to pump liquid fuel from a fuel tank through a fuel handling system to an engine that powers the vehicle.
2) Background Information
In an automotive vehicle that is powered by an internal combustion engine, fuel may be pumped through a fuel handling system of the engine by an in-tank, electric-motor-operated fuel pump.
Examples of fuel pumps are shown in various patents, including U.S. Pat. Nos. 3,851,998; 5,310,308; 5,409,357; 5,415,521; 5,551,875; and 5,601,398. Commonly owned U.S. Pat. Nos. 5,310,308; 5,409,357; and 5,551,835 disclose pumps of the general type to which the present invention relates, and such pumps provide certain benefits and advantages over certain other types of pumps.
For developing pressures suitable for a vehicle fuel system, the impeller of a regenerative pump may have very close running tolerances to the walls of the pump parts that axially confront opposite faces of the impeller internally of the pump. Hence, dimensional stability of materials is an important design consideration, and certain materials have been found particularly suitable for the impeller and for the parts of the pump (a pump cover and a pump body, for example) that confront it. PPS and phenolic are examples of suitable impeller materials; those two materials, as well as aluminum, are suitable for the pump cover and pump body.
A representative pump is a wet pump that comprises an inlet in the pump cover and an outlet in the pump body. The inlet and the outlet are open to an annular pumping chamber that runs around the perimeter of the pump. The impeller comprises vanes that rotate within the pumping chamber to move fluid from the inlet to the outlet. When the pump is disposed within a fuel tank with its axis generally vertical and the cover facing a bottom wall of the tank, the inlet is open to liquid fuel in the tank. When the pump is operated by an associated electric motor, some pressure difference is developed across those portions of the impeller faces which are disposed radially inward of the annular pumping chamber and which have close running fits to confronting wall surfaces of the pump cover and the pump body, thus creating a force imbalance that acts on the impeller in a downward direction. The force of gravity is additive to that downward force imbalance. Force imbalance may act on an impeller in ways that increase running friction. Such friction may decrease pump efficiency and accelerate wear that leads to even further loss of pumping efficiency.
Various solutions have been proposed to minimize, and ideally eliminate, force imbalance acting on the impeller. Examples are found in U.S. Pat. Nos. 3,768,920; 4,586,877; 4,854,830; 4,872,806; 5,137,418; and 5,607,283.
SUMMARY OF THE INVENTION
Through continuing development, it has been discovered the inclusion of certain features in an impeller can provide a better solution to the force imbalance problem described above.
Because those features are incorporated in the impeller, they can be inherently created when an impeller that embodies them is fabricated by known impeller fabrication methods. Hence, the solution provided by the present invention is significantly cost-effective.
Briefly, the invention relates to the inclusion of what the inventors have called “lifting tail grooves” in association with force-balance through-holes that extend between opposite impeller faces. The lifting tail grooves are provided in the face of the impeller that is toward the pump inlet, sometimes herein called the down-face for convenience because it faces down when the pump is mounted inside a fuel tank in the manner mentioned above. Each lifting tail groove comprises a shaped cavity that adjoins a respective force-balance through-hole, and runs a short distance circumferentially in a sense that is opposite the sense in which the impeller is rotating. Hence each groove “tails away” from the respective through-hole.
Importantly, each lifting tail groove comprises a fluid reaction surface that is non-parallel to the plane of the impeller down-face. It is believed that as the impeller rotates, fluid lamina between the impeller down-face and the confronting wall surface of the pump cover tends to rotate in the same sense as the impeller, but at a slower velocity because of its inherent viscosity. Hence, it is believed that the fluid lamina tends to rotate counter-clockwise relative to the impeller.
After the fluid lamina has passed across a force-balance through-hole and begins to encounter the respective lifting tail groove, it acts on the fluid reaction surface of the lifting tail groove in a manner that has been found to create a useful upward component of force that is opposite the pressure-induced force imbalance acting on the impeller. This effect significantly improves force-balancing of the impeller.
A representative impeller may have a number of identical force-balance through-holes distributed in a uniform pattern with respect to the impeller axis. Identical lifting tail grooves are associated with the force-balance through-holes.
One general aspect of the present invention relates to a pump comprising: a pump housing comprising an internal pumping chamber and a fluid inlet to, and a fluid outlet from, the pumping chamber spaced arcuately apart about an axis; and a pumping element that is disposed within the housing for rotation about the axis and that has a body comprising a vaned periphery operable with respect to the pumping chamber to pump fluid from the inlet to the outlet when the pumping element is rotated, the pumping element body further having mutually parallel opposite faces circumferentially bounded by its vaned periphery. The pump housing comprises wall surfaces confronting the opposite faces of the pumping element body with close running clearance, the inlet being proximate one wall surface and the outlet being proximate the other wall surface. The pumping element body comprises a pattern of through-holes extending between its faces with the one face that confronts the wall surface to which the inlet is proximate further comprising in association with each through-hole, a groove that adjoins and tails circumferentially away from the respective through-hole in a sense opposite the sense in which the pumping element rotates to pump fluid from the inlet to the outlet and that inclines from the through-hole to end by merging with the one face of the pumping element body at a location spaced circumferentially from the respective through-hole.
Another general aspect relates to a pump comprising: a pump housing comprising an internal pumping chamber and a fluid inlet to, and a fluid outlet from, the pumping chamber spaced arcuately apart about an axis; and a pumping element that is disposed within the housing for rotation about the axis and that has a body comprising a vaned periphery operable with respect to the pumping chamber to pump fluid from the inlet to the outlet when the pumping element is rotated, the pumping element body further having mutually parallel opposite faces circumferentially bounded by its vaned periphery. The pump housing comprises wall surfaces confronting the opposite faces of the pumping element body with close running clearance, the inlet being proximate one wall surface and the outlet being proximate the other wall surface. The pumping element body comprises a pattern of through-holes that have wall surfaces extending parallel to the pump axis between its faces with the one face that confronts the wall surface to which the inlet is proximate further comprising in association with each through-hole, a groove that adjoins and tails circumferentially away from the respective through-hole along an arc that is concentric with the pump axis in a sense opposite the sense in which the pumping element rotates to pump fluid from the inlet to the outlet, and
Verkleeren Ronald Luce
Yu Dequan
Look Edward K.
Mollon Mark
Visteon Global Technologies Inc.
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