In-Tank Fuel Reservoir With Fuel Vapor Separation

The invention, together with additional objects, features and advantages thereof, will be best understood from the following description, the appended claims and the accompanying drawing which is a fragmentary sectional view in side elevation of a fuel delivery module in accordance with a presently preferred embodiment of the invention.

The drawing illustrates a fuel delivery module 10 in accordance with a presently preferred embodiment of the invention as comprising a substantially cylindrical canister 12 having an open top and bottom. A canister support 14 encircles the open lower edge of canister 12 and is adapted to rest on the bottom of a fuel tank 18. An internal wall 20 within canister 12 forms and separates a lower chamber 22 at the open bottom of canister 12 from an upper chamber 24. A circumferential opening 16 in support 14 admits fuel to lower chamber 22 from the surrounding fuel tank. An electric-motor fuel pump 26 is positioned within upper chamber 24. Pump 26 has an inlet 28 which extends through wall 20 to draw fuel from lower chamber 22, and has a primary outlet 30 for delivering fuel under pressure through a suitable fuel line 32 to an engine or other fuel consumer. Excess fuel from the engine is returned through a line 34 to upper canister chamber 24.

A mesh filter 36 spans the open lower end of canister 12, being ultrasonically welded around its periphery to an annular shoulder 38 on wall 20. A lever 40 has a central portion pivotally mounted to wall 20 within lower chamber 22 and is coupled at one end to a web 42 centrally carried by filter 36. A spring 43 is captured in compression between lever 40 and wall 20 for urging lever 40 and web 42 in the downward direction. The opposing end of lever 40 is coupled to a valve element 44 positioned within an opening or passage 46 in wall 20. Filter 36 is characterized by permitting free passage of liquid fuel therethrough, while being closed by surface tension of liquid fuel to restrict passage of air therethrough. Thus, in the event of absence of fuel available through opening 16, suction pressure of pump 26 pulls filter 36 upwardly against the force of spring 43, with lever 40 thus moving valve 44 downwardly and thereby permitting flow of fuel from upper chamber 24 into lower chamber 22 and thence to pump inlet 28. On the other hand, as long as fuel is available at opening 16, valve element 44 is urged by spring 43 to the closed position illustrated in the drawing. To the extent thus far described, fuel module 10 is essentially similar to the those disclosed in the aboveidentified applications, to which reference may be had for further detailed discussion.

In accordance with the present invention, pump 26 has a secondary outlet 50 which extends downwardly therefrom adjacent and parallel to inlet passage 28. With the exception of secondary fuel outlet 50, pump 44 is as disclosed in U.S. Pat. No. 4,596,519 assigned to the assignee hereof and incorporated herein by reference. Secondary outlet 50 is formed in the pump of the referenced disclosure as a passage which extends to the case or volume which surrounds the pump rotor and is at pump outlet pressure. Secondary outlet 50 delivers fuel under pressure at a lesser volume than primary outlet 30. A fluid conduit 52 includes an inlet portion 54 which extends upwardly from lower chamber 22 parallel to pump inlet 28, and an outlet portion 56 which extends laterally or radially from inlet portion 54 into upper chamber 24. A nozzle in the form of an orifice 58 extends through the wall of fluid conduit 52 in axial opposed alignment with conduit outlet portion 56 and couples conduit 52 to secondary pump outlet 50. It will be noted that the inlet portion 54 of conduit 52 is in the form of an enlarged chamber positioned laterally adjacent to pump inlet 28. A standpipe 60 extends from conduit outlet portion 56 upwardly within canister upper chamber 24 to a position corresponding to the maximum desired level of fuel within canister chamber 24.

In operation, fuel is drawn by pump 26 through inlet 28 and fed through outlet 30 to the engine as previously described. In the meantime, a lesser quantity of fuel supplied at secondary pump outlet 50 is fed under pressure through nozzle orifice 58 and thereby jet-aspirates vapor and fuel from within lower chamber 22 through standpipe 60 to the top of upper chamber 24. Any vapors entrained in fuel entering opening 16 are thereby expelled through standpipe 60 at the upper end of canister 12. The location of the top of standpipe 60 at the maximum fuel level of the canister prevents any backflow of fuel into the standpipe.