Fuel pump having electrically biased shell
View Patent ↗A fuel pump is provided that is submersible within a fuel, for example, within a fuel tank of an automotive vehicle and is particularly suited for use with high alcohol content fuels that tend to contain ionic species. The fuel pump comprises an electric motor that includes a commutator and a negative brush electrode that is connected to a negative terminal of an external power supply. The electric motor is at least partially disposed within a metal shell that is in contact with the fuel. The metal shell is also connected to the negative terminal of the external power supply. During operation, a negative electrical potential is applied to the metal shell to preferentially react with ions within the fuel. In this manner, the metal shell serves as a anode to reduce the concentration of ionic species in the fuel, thereby decreasing reactions with the brush electrode and extending the useful life of the fuel pump.
1. A fuel pump submersible within a fuel inside a fuel tank, the fuel pump comprising:
an outer housing defined in part by a metal shell adapted for contact with the fuel, the outer surface of the metal shell contacting fuel in the fuel tank, the inner surface of the metal shell contacting fuel in the fuel pump;
an electric motor comprising a commutator and a negative brush electrode adapted for connection to a negative terminal of an external power supply; and
means for connecting the metal shell to the negative terminal to apply a negative electrical potential to said metal shell effective to preferentially react with ions within the fuel located in the fuel tank and in the fuel pump to reduce the concentration of ionic species in the fuel and decrease reactions with the negative brush.
2. A fuel pump in accordance with claim 1 wherein the brush electrode is composed of high purity carbon material.
3. A fuel pump in accordance with claim 2 wherein the high purity carbon material does not contain a metal element in an amount greater than 600 ppm.
4. A fuel pump in accordance with claim 2 wherein the metal shell is formed of steel.
5. A fuel pump in accordance with claim 2 wherein the metal shell defines an internal cavity for pumping fuel through the fuel pump.
6. A fuel pump submersible in a high alcohol fuel within a fuel tank of an automotive vehicle and comprising:
a metal shell adapted for contact with said high alcohol fuel;
an outlet housing closing off one end of the metal shell, the outlet housing constructed of a non-conductive material;
an electric motor at least partially disposed within the metal shell, said electric motor including a commutator and a negative electrode assembly comprising a carbon brush electrode slideably contacting the commutator, said carbon brush electrode being formed of substantially metal-free carbon material and connected to a negative terminal of an external power supply, the negative electrode assembly extending through the outlet housing; and
an electrically conductive pathway formed within the outlet housing for electrically connecting the metal shell to the negative electrode assembly for applying a negative electrical potential to the metal shell effective to reduce ions within the high alcohol fuel.
7. A fuel pump in accordance with claim 6 wherein a metallic connector connecting the negative electrode assembly to the metal shell.
8. A fuel pump in accordance with claim 6 wherein said carbon brush is composed of a high purity carbon metal containing no metal in an amount greater than 600 ppm.
9. A fuel pump in accordance with claim 7 , wherein the metal connector is embedded in the outlet housing.
10. A fuel pump in accordance with claim 9 , wherein the metal connector has a first end contacting the metal shell, the first end defining a spring loop.
11. A fuel pump in accordance with claim 10 , wherein the outlet housing defines a slot receiving the spring loop of the first end.
12. A fuel pump in accordance with claim 10 , wherein an edge of the metal shell engages the outlet housing, the spring loop at the first end of the metal connector being deformed by the edge of the metal shell.
13. A fuel pump in accordance with claim 12 wherein the edge of the metal shell is a rolled edge that engages the outlet housing.
14. A fuel pump in accordance with claim 9 , wherein the metal connector has a second end contacting the negative electrode assembly, the second end having on annular shape extending around the periphery of the negative electrode assembly.
15. A fuel pump in accordance with claim 6 , wherein the outer surface of the metal shell contacts fuel within the fuel tank, and wherein the inner surface of the metal shell contacts fuel with an internal cavity defined by the metal shell.
16. A fuel pump in accordance with claim 1 , wherein the outer housing is further defined by an outlet housing dosing off an end of the metal shell, the outlet housing being formed of a non-conductive material.
17. A fuel pump in accordance with claim 16 , wherein the means for connecting includes a metal strip embedded within the outlet housing.
18. A fuel pump in accordance with claim 17 , wherein the metal shell is connected to the outlet housing by rolling an edge of the metal shell, and wherein the metal strip has a first end defining a spring loop, the spring loop being deformed by the rolled edge of the metal shell.
19. A fuel pump in accordance with claim 18 , wherein the outlet housing defines a slot receiving the spring loop of the first end.
20. A fuel pump in accordance with claim 19 , wherein the metal strip has a second end contacting the negative electrode assembly, the second end having an annular shape extending around the periphery of the negative electrode assembly.
21. A fuel pump in accordance with claim 1 , wherein the metal shell is connected in series to the negative terminal.