MODULAR FUEL DELIVERY APPARATUS

Abstract: A modular fuel delivery apparatus including a reservoir (20) in a fuel tank (10), an electric high pressure fuel pump (40) in the reservoir fed only from inside the reservoir, and a jet pump (52) fed only from the fuel tank and discharging into the reservoir to keep the latter filled and energized from the high pressure fuel pump. A check valve is disposed between the jet pump inlet (58) and the fuel tank to prevent backflow into the fuel tank. A partition (88) on the bottom (36) of the reservoir separates the jet pump discharge (60) from the high pressure pump inlet and defines a standpipe around and above the jet pump discharge so that the jet pump discharge stays submerged in fuel when the high pressure pump empties the reservoir. The pumping efficiency of the jet pump when submerged is better than when dry so that the delay in restarting the engine after both the fuel tank and the reservoir are pumped empty is minimized.

Description: This invention relates to automotive modular fuel delivery apparatus including an in-tank reservoir, a high pressure fuel pump in the reservoir, and a jet pump for filling the reservoir. In automotive modular fuel delivery apparatus such as described in US-A-4,945,884, a canister-like reservoir in a fuel tank encloses an electric, high pressure fuel pump fed only from inside the reservoir. Advantages of such apparatus include modular handling and installation of fuel system components and minimization of the likelihood of fuel starvation at the high pressure fuel pump inlet when the vehicle turns a corner. Various proposals have been advanced for keeping the reservoir full. In US-A-4,860,714, for example, a jet pump at the bottom of the reseroivr pumps fuel from the fuel tank into the reservoir and is powered by a fraction of the discharge of the high pressure fuel pump. The delay in restarting the engine with a limited quantity of fuel after the jet pump pumps the fuel tank dry and the high pressure fuel pump pumps the reservoir dry is undesirably maximized if, as in the aforesaid US-A-4,860,714, the jet pump is dry at the beginning of the restart sequence. The preambule of claim 1 corresponds to an apparatus according to this document. Another form of fuel delivery apparatus incorporating a jet pump is disclosed in EP-A-0,314,068. In a device according to this document, the jet pump is also dry at the beginning of the restart sequence. A modular fuel delivery apparatus in accordance with the present invention comprises a reservoir in a fuel chamber of a fuel tank adjacent a bottom wall of the fuel tank; a high pressure fuel pump in the reservoir having an inlet fed only from inside the reservoir; a jet pump in the reservoir having an inlet section fed only from the fuel chamber and a discharge section feeding only into the reservoir; means for energizing the jet pump with a fraction of the output of the high pressure fuel pump so that the jet pump is supplied with fuel when the high pressure fuel pump is operating primed and supplied with vapour when the high pressure fuel pump is operating unprimed; means defining a check valve between the inlet section of the jet pump and the fuel chamber for preventing backflow from the jet pump into the fuel chamber; and means in the reservoir defining a standpipe comprising a partition on a bottom of the reservoir having an upper edge above the discharge section of the jet pump thereby separating the discharge section of the jet pump from the inlet of the high pressure fuel pump so that the discharge section of the jet pump remains submerged in fuel when the reservoir is emptied of fuel by the high pressure fuel pump. In a modular fuel delivery apparatus according to this invention, the jet pump is maintained submerged to minimize the delay in restarting the engine. This invention is a new and improved modular fuel delivery apparatus including a reservoir in a fuel tank, a high pressure fuel pump in the reservoir fed only from inside the reservoir, and a jet pump for pumping fuel from the fuel tank into the reservoir. In the modular fuel delivery apparatus according to this invention, a check valve prevents backflow from the jet pump into the fuel tank and the discharge of the jet pump is located in a standpipe the top of which is above the discharge so that jet pump stays submerged when the reservoir is emptied. The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:- Figure 1 is a partially broken-away elevational view of an automobile fuel tank having installed thereon a modular fuel delivery apparatus according to this invention; Figure 2 is a partially broken-away perspective view of the modular fuel delivery apparatus according to this invention; Figure 3 is a plan view taken generally along the plane indicated by lines 3-3 in Figure 2; Figure 4 is a view taken generally along the plane indicated by lines 4-4 in Figure 3; and Figure 5 is a view taken generally along the plane indicated by lines 5-5 in Figure 3. Referring to Figures 1 and 2, a fuel tank 10 of an automobile, not shown, has an internal volume or fuel chamber 12 defined between a top wall 14 and a bottom wall 16 of the tank. The top wall 14 has a hole or access port therein for installation of a modular fuel delivery apparatus 18 according to this invention. The modular fuel delivery apparatus 18 includes a (canister-like plastic) reservoir 20 and a (plastic) cover 22. The cover 22 closes the access port in the fuel tank 10 and has a plurality of fluid connectors 24A-C thereon for attachment, respectively, to a high pressure hose to the engine, a vapour purge, and a low pressure return hose from the engine. A plurality of tubular struts 26 attached to the cover 22 are telescopically received in the reservoir 20 so that the reservoir and the cover are movable toward and away from each other. One of the tubular struts 26 is connected through the cover 22 to the fluid connector 24C and defines a fuel return duct to the reservoir 20. A plurality of springs 28 around the struts 26 urge relative separation between the cover 22 and the reservoir 20. When the cover 22 is attached to the top wall 14, the springs 28 hold the reservoir 20 against the bottom wall 16. A bottom referenced fuel level sensor 30 is mounted on a side bar 32 attached to the reservoir 20. The reservoir 20 has a cylindrical side wall 34 and a generally flat bottom 36. A (plastic) retainer 38, Figure 2, closes the reservoir 20. A schematically represented electric, high pressure fuel pump 40, Figure 3, is suspended inside the reservoir 20 from a high pressure connector 42, Figure 2, on the retainer 38. Near the bottom of the reservoir 20, the high pressure fuel pump 40 has an inlet, not shown, covered by a secondary screen 44, Figure 3. The inlet of the high pressure fuel pump 40 is fed through the secondary screen 44 only from inside the reservoir 20. An intermediate wiring harness 46 connects the high pressure fuel pump 40 and the fuel level sensor 30 to the main wiring harness, not shown, of the vehicle through an electrical connector 48 on the cover 22. A high pressure hose 50 extends between the high pressure connector 42 and the fluid connector 24A on the cover 22. The modular fuel delivery apparatus 18 further includes a jet pump 52 in the reservoir 20. A (plastic) housing 54 of the jet pump 52 has a cylindrical mounting flange 56, Figure 4, an inlet section 58 substantially perpendicular to the flat bottom 36 of the reservoir 20, and a discharge section 60 substantially parallel to the flat bottom 36. The cylindrical mounting flange 56 fits in an aperture 62 in a raised portion of the flat bottom 36 of the reservoir 20 and is welded or otherwise sealingly attached to the reservoir. A primary screen 64 is attached to the cylindrical mounting flange 56 and rests on the bottom wall 16 of the fuel tank 10. The inlet section 58 has an internal passage 66 which opens into a valve chamber 68 in the housing 54. The discharge section 60 has an internal, expanding diameter venturi passage 70 therein extending from the valve chamber 68 to a discharge end 72 at the end of the discharge section 60. A perforated, plastic check valve seat 74 is rigidly connected to the cylindrical mounting flange 56 of the jet pump housing and supports a reciprocating or equivalent check valve element 76. The valve element 76 has a closed position, Figure 4, covering the perforations in the valve seat 74 and an open position, not shown, exposing the perforations. In the open position of the valve element 76, fuel flows from the fuel chamber 12 into the valve chamber 68 through the primary screen 64 and through the perforations in the valve seat 74. In the closed position of the valve element 76, backflow from the valve chamber 68 into the fuel chamber 12 is foreclosed. A fluid connector 78 is press fitted onto the upper end of the inlet section 58 of the housing 54 and supports a strainer 80 in the internal passage 66. A jet pump tube 82 extends between the fluid connector 78 and the high pressure connector 42 on the retainer 38 and conducts a fraction of the discharge of the high pressure fuel pump 40 to the internal passage 66 of the jet pump 52. A brass nozzle 84 with an orifice 86 therein is press fitted in the housing 54 at the lower end of the internal passage 66 with the orifice 86 facing the venturi passage 70. The fraction of the discharge of the high pressure fuel pump 40 conducted to the internal passage 66 by the jet pump tube 82 exits the orifice 86 into the venturi passage 70 as a high velocity stream substantially parallel to the flat bottom 36 of the reservoir 20. In conventional jet pump fashion, the high velocity stream entrains and conducts fuel from the valve chamber 68 into the reservoir 20 through the venturi passage 70. In appropriate applications, the jet pump could be energized by return flow from the engine as described in GB Patent No. 1,591,978. As seen best in Figures 3-5, the primary screen 64 and the inlet to the high pressure fuel pump 40 are separated from the discharge end 72 of the discharge section of the jet pump 52 by a partition 88 integral with the flat bottom 36 and side wall 34 of the reservoir 20. The partition 88 has an upper edge 90 above the discharge end 72 and cooperates with the side wall 34 of the reservoir 20 in defining a fluid standpipe around the discharge section 60 of the jet pump 52 higher than the discharge end 72. Normally, the jet pump 52 pumps enough fuel to keep the reservoir 20 filled regardless of the flow rate out of the reservoir 20 from the high pressure fuel pump 20. Without refuelling, however, the jet pump 52 empties the fuel chamber 12 to below the lower edge of the cylindrical mounting flange 56. Thereafter, the high pressure fuel pump 40 empties the reservoir 20 to below the inlet to the high pressure fuel pump, a level below the upper edge 90 of the partition 88. The standpipe defined by the partition 88 and side wall 34 of the reservoir 20 traps or captures a pool of fuel around the discharge section 60 of the jet pump 52 to a level above the discharge end 72. The check valve element 76 prevents the captured fuel in the standpipe from draining back into the fuel chamber 12. When the engine stops after the reservoir 20 and fuel tank 10 are emptied as described above, only 3.75 litres or less of fuel is usually available to restart the engine. That small quantity of fuel is not usually sufficient for self-migration past the check valve element 76 into the reservoir 20 to a level above the inlet to the high pressure fuel pump 40. Accordingly, a delay is experienced in restarting the engine until enough fuel is pumped by the jet pump 52 into the reservoir 20 to prime the high pressure fuel pump 40. The partition 88 minimizes the delay in restarting the engine. More particularly, the unprimed high pressure fuel pump 40 discharges vapour into the high pressure connector 42 and, through the jet pump tube 82, into the internal passage 66 in the inlet section 58 of the jet pump 52. The vapour exits the orifice 86 into the venturi passage 70 as a vapour jet. The vapour jet is submerged in the fuel captured in the standpipe defined by the partition 88 and, therfore, virtually immediately commences entraining or pumping fuel into the reservoir 20, albeit at reduced efficiency. The fuel overflows the upper edge 90 of the partition 88 and rises in the remainder of the reservoir 20 until the high pressure fuel pump 40 is primed. Then, the high pressure fuel pump 40 commences pumping fuel to the engine for restart and to the jet pump 52 which thereupon achieves full pumping efficiency for rapid filling of the reservoir 20 to sustain the engine. In the absence of the partition 88, the delay in restarting engine is longer. That is, without the partition 88, the high pressure fuel pump 40 empties the reservoir 20 to below the discharge end 72 of the discharge section 60 of the jet pump 52 after the jet pump empties the fuel chamber 12. Therefore, the jet pump 52 is essentially dry at the commencement of the restart sequence described above and operating at minimum efficiency because the vapour jet emanating from the orifice 86 defines a high velocity vapour stream into essentially only vapour rather than into liquid fuel as occurred with the partition 88 in place. Tests comparing a modular fuel delivery apparatus without a standpipe-defining partition in place to an identical modular fuel delivery apparatus according to this invention with a partition 88 in place demonstrated about a ten-fold improvement. After adding 450 ml of fuel to a pumped-empty fuel tank, the delay in restarting the engine was about 47 seconds for the modular fuel delivery apparatus having a reservoir without a partition as compared to 4.7 - 6.0 seconds for an otherwise identical modular fuel delivery apparatus wherein the reservoir 20 included the partition.

Claims: A modular fuel delivery apparatus comprising a reservoir (20) in a fuel chamber (12) of a fuel tank (10) adjacent a bottom wall (16) of the fuel tank; a high pressure fuel pump (40) in the reservoir having an inlet fed only from inside the reservoir; a jet pump (52) in the reservoir having an inlet section (58) fed only from the fuel chamber and a discharge section (60) feeding only into the reservoir; means (82) for energizing the jet pump with a fraction of the output of the high pressure fuel pump so that the jet pump is supplied with fuel when the high pressure fuel pump is operating primed and supplied with vapour when the high pressure fuel pump is operating unprimed; and means defining a check valve (76) between the inlet section of the jet pump and the fuel chamber for preventing backflow from the jet pump into the fuel chamber; characterised by means (88) in the reservoir defining a standpipe comprising a partition (88) on a bottom (36) of the reservoir having an upper edge (90) above the discharge section of the jet pump thereby separating the discharge section of the jet pump from the inlet of the high pressure fuel pump so that the discharge section of the jet pump remains submerged in fuel when the reservoir is emptied of fuel by the high pressure fuel pump. A modular fuel delivery apparatus as claimed in claim 1, wherein the partition (88) on the bottom (36) of the reservoir has opposite ends sealingly connected to a side wall (34) of the reservoir. A modular fuel delivery apparatus as claimed in claim 2, wherein the reservoir (20) and the partition (88) are plastic and moulded integrally.

Inventors: COHA, TIMOTHY F., MCGRATH, DENNIS P., SAWERT, ULF
Applicants: GENERAL MOTORS CORPORATION
Application year: 1991
Main classification: F02M37
IPC codes: F02M37