Two stage fuel pump
A fuel pump for an engine having an engine condition representative of engine speed is described comprising: a housing having a fuel inlet and a fuel outlet. The fuel inlet is open to a fuel inlet chamber formed in the housing, a first pump stage having an inlet open to the inlet chamber and an outlet open to an intermediate chamber formed in the housing, a second pump stage having an inlet open to the intermediate chamber and an outlet, wherein the first and second pump stages are vane pump stages and means for coaxially mechanically securing the vane pump stages together for rotation in unison with each other, means for fluidly connecting the second pump stage outlet to the fuel outlet, means for maintaining the pressure in the intermediate chamber below a predetermined maximum amount, wherein the maintaining means comprises means for fluidly connecting the intermediate chamber to the inlet chamber only when the pressure in the intermediate chamber exceeds the predetermined amount, means fluidly connected to the second pump stage output and responsive to the engine condition for variably fluidly connecting the second pump stage output to the inlet chamber, wherein the variable fluid connecting means comprises a return fluid passageway in the housing fluidly connecting the second stage outlet with the inlet chamber, an orifice in series with and at a midpoint of the return fluid passageway, an outlet fluid passageway fluidly connecting the orifice to the housing outlet, and movable valve means responsive to the engine condition for variably restricting the orifice so that fuel flow from the fluid passageway is variably divided between the return passageway and the outlet passageway as a function of the position of the valve means in amounts inversely proportional to each other.
- Assignee:
- Teledyne Industries, Inc., Los Angeles, CA
- Patent Number(s):
- US 4700680
- OSTI ID:
- 5777030
- Country of Publication:
- United States
- Language:
- English
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