Rotary kinetic fluid motors or pumps – With means for re-entry of working fluid to blade set – Turbine regenerative pump
Reexamination Certificate
2000-01-13
2001-10-23
Kwon, John (Department: 3745)
Rotary kinetic fluid motors or pumps
With means for re-entry of working fluid to blade set
Turbine regenerative pump
Reexamination Certificate
active
06305900
ABSTRACT:
TECHNICAL FIELD
The present invention relates to vehicle fuel pumps and more particularly to a non-corrosive regenerative fuel pump housing for use in an automobile.
BACKGROUND
Conventional tank-mounted automotive fuel pumps typically have a rotary-pumping element, such as an impeller with a plurality of grooves encased within a pump housing. Rotation of the impeller draws fuel into a pumping chamber within the pump housing. The rotary pumping action of the vanes and the vane grooves of the impeller causes the fuel to exit the housing at high-pressure. Regenerative turbine fuel pumps are commonly used to pump fuel in automotive engines because they have a more constant discharge pressure than, for example, positive displacement pumps. In addition, regenerative turbine pumps typically cost less and generate less audible noise during operation.
As fuel pumps get smaller and smaller to achieve higher pressures, the housing that contains the pumps have tighter tolerances. To achieve these tolerances, the current housings are made of anodized aluminum. Anodized aluminum works well in pure gasoline systems, but has a tendency to corrode when gasoline is mixed with flex fuels or other aggressive fuels such as methanol/gasoline or ethanol/gasoline mixtures.
Various solutions have been attempted to replace anodized aluminum in fuel pump housing. One solution is to coat the anodized aluminum, however this is very costly. Another possible solution uses a thermoplastic or thermosetting material to replace the anodized aluminum housing designs. However, conventional housing using thermoplastic or thermosetting materials typically experience one of two problems. First, thermoplastic or thermosetting housings having narrow seal surfaces between the cover and the housing cannot be used in high-pressure applications (greater than 100 kpa) because their narrow seal surfaces tend to creep. Second, where the seal surface width is increased to combat creep and allow the housings to be used in higher pressure (300-500 kpa) applications, the friction generated between the housing and the impeller increases.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to introduce a new pump housing to replace anodized aluminum housings in regenerative fuel pumps. The present invention overcomes the present obstacles by introducing a non-corrosive, lower cost pump housing made of thermoplastic or thermoset materials that can be used in higher pressure (300-500 kpa) applications. The present invention reduces leakage associated with creep compared to other thermoplastic or thermoset housings by introducing new designs for the cover and the body of the housing that have a double sealing surface. The present invention also eliminates corrosion of the housing due to flex fuel or other aggressive fuel systems as compared with conventional anodized aluminum housings. In addition, the present invention limits friction as compared with other thermoset or thermoplastic conventional housings used in higher-pressure applications.
A preferred embodiment of the improved fuel pump for use in high-pressure applications with aggressive or flex fuels consists of a non-corrosive pump housing having a pump cover and pump body, a motor mounted within the pump housing having a shaft, and an impeller located between the pump cover and pump body connected to the shaft for rotatably pumping fuel. The pump body and pump cover are each comprised of a narrow seal ring, a cavity core, and a tapered seal ring extending radially between the narrow seal ring and the cavity core.
The narrow seal rings prevent appreciable leakage between the pump cover or pump body and the impeller. Further, the tapered seal ring provides a secondary protection against leakage should the narrow seal rings creep slightly.
The narrowness of the narrow seal rings, preferably around 1-3 millimeters wide (substantially less than presently available non-corrosive pump covers and pump bodies used in high pressure applications, which are typically around 8 millimeters in width), decreases the friction between the pump housing and the impeller, which increases turn increases the efficiency pumping action.
The increased taper ratios (3-5 times greater than typical anodized aluminum designs) along the tapered seal ring results in a decrease in friction between the pump cover and impeller and the pump body and impeller, respectively, as compared with anodized aluminum housings.
Further, the new design of the narrow seal ring in the pump covers and pump bodies does not creep appreciably, and thus can be used in higher-pressure applications (300-500 kpa) that are standard for present-day automotive fuel pump systems.
Other objects and advantages of the present invention will become apparent upon considering the following detailed description and appended claims, and upon reference to the accompanying drawings.
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Kajander John E.
Kwon John
Visteon Global Technologies Inc.
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