Patent Application
20070074770
The invention relates to a modular fuel reservoir assembly in a motor vehicle fuel tank.
Present day vehicle fuel systems may include an assembly commonly referred to as a “modular fuel reservoir” (MFR) assembly in the fuel tank of the motor vehicle. A typical MFR includes a tank cover, a cup-shaped plastic reservoir, a plurality of guide rods on the tank cover slidably connected to the reservoir, and a spring urging relative separation between the tank cover and the reservoir. The MFR is inserted into the fuel tank through an access port in the top of the fuel tank which is sealed closed by the tank cover and a rubber seal. The spring biases the reservoir against the bottom of the fuel tank. A plastic retainer on the top of the plastic reservoir locates a fuel pump and fuel filter in the reservoir. The electric motor of the fuel pump is turned on and off through a wiring harness of the motor vehicle. When the electric motor is on, the pump pumps fuel at elevated pressure from the reservoir through the filter, ultimately leading through the fuel lines to the vehicle engine. Vertical tubes positioned in the reservoir direct fuel from the tank, as well as fuel that has bypassed the fuel outlet of the MFR, to the reservoir wherein the pump is located. This ensures fuel surrounds the pump until the tank is close to being fully depleted of fuel.
In commonly assigned prior U.S. Pat. No. 6,216,671, a MFR is disclosed that establishes electrical connection between an electrically conductive retainer, fuel regulator and fuel pump sheath leading to vehicle ground. As seen in
Since the time of the '671 patent, it is now required that the vertical return and fill tubes themselves be electrically conductive and/or dissipative. One solution would be to make the integrally formed reservoir and tubes of the '671 device from an electrically conductive plastic material, however, this would undesirably add to material cost. Conductive plastic is more expensive than non-conductive plastic and there is no requirement for the reservoir walls to be conductive and/or dissipative. Therefore, there exists a need for an improved MFR having conductive and/or dissipative supply and fill tubes and which maintains a low pick-up point for the jet pump and does not sacrifice cost and quality.
The present invention addresses the above need by providing an improved MFR having a reservoir and retainer for locating the pump and fuel filter in the reservoir. The reservoir includes a bottom wall leading to an inner, vertically extending wall structure defining an open, vertical column extending from an opening in the bottom wall to an opening located adjacent or just below the top perimeter of the reservoir. The reservoir may be made of non-conductive plastic, for example. The retainer is made from an electrically conductive material such as, for example, an electrically conductive resin. The retainer is configured to attach to the top perimeter of the reservoir and securely locate the pump, filter and other desired components in the reservoir. The retainer further includes integrally formed vertical supply and fill tubes which are received within the open vertical column of the reservoir with the open bottom ends of the tubes exposed at the bottom opening of the reservoir column for attachment of a jet pump thereto. A low pick-up point for the jet pump is therefore maintained in the inventive design. The retainer and vertical supply and fill tubes are preferably integrally molded in one piece from the same conductive material.
The present invention will now be described, by way of example, with reference to the accompanying drawings, in which:
A seen best in
Reservoir 14 includes a side wall 34 and a bottom wall 36 leading inwardly to an open, vertically extending wall structure defining a column 35 having an open top defined by the column top edge 37, and an open bottom defined by the column bottom edge 39. Reservoir 14 is open at a top edge 38 thereof, and optionally flattened on a side wall 40 thereof to assist in securing any desired additional components thereto.
A retainer 76 of the MRA 10 (shown in section in
A venturi jet pump 46 includes an inlet port 48 which connects to open bottom end 42′ of supply tube 42 adjacent reservoir bottom wall 36 (see
Retainer 76, including integrally formed tubes 42 and 44, is formed (e.g., by injection molding) as a unitary piece from an electrically conductive material such as, for example, Celcon EC90PLUS, an acetal copolymer available commercially from Ticona, a division of Celanese Corporation. A fuel pump 90 of the MFR 10 (see
The fuel pump 90 is supported outside of the tubular chamber 35 on a fuel strainer 108 having an opening 110 that aligns with a fuel inlet (not shown) at the bottom end housing 94 of the pump 90. The retainer 76 bears directly against the metal shell 92 of the fuel pump 90 and establishes an electrically conductive interface therebetween. A discharge passage 114 extending from the fuel pump is connected to the fuel inlet 116 on fuel filter 93 via conduit 118.
Thus, when the electric motor of the fuel pump 90 is on, pump 90 pumps fuel from the reservoir 14 to the fuel filter 93. The fuel passes through the filter 93 and exits at outlet 122, continuing through conduit 124 to discharge fluid connector 28 on cover 16, ultimately leading to the vehicle engine. A pressure control valve 126 is positioned near the bottom wall of filter 93 to allow excess fuel to flow through outlet 128 back into reservoir 14. In this way, valve 126 ensures proper pressure is maintained in the fuel lines.
Fuel may be drawn into the reservoir 14 in the following additional ways. First, a feed connector 120 includes a fitting 121 which press fits into the open top end 42″ of supply tube 42. The opposite end 123 thereof fits into a connector 125 which taps into fuel inlet 116 of fuel filter 93. Thus, as fuel is pumped to the fuel filter inlet 116, a fraction of the fuel is diverted through the feed connector 120 and into the supply tube 42. The diverted fuel in the supply tube 42 enters the motive fluid inlet 48 of the jet pump and is discharged into the fill tube 44 as a jet which acts to aspirate fuel from the fuel tank 12 into the reservoir 14 to maintain the reservoir filled with fuel until the fuel tank is completely depleted. Fuel traveling through fill tube 44 is ejected at the top opening 44″ thereof, striking deflector 119 of connector 120 and is thereby directed back into reservoir 14. Fuel may also enter reservoir 14 through inlet 15 located at the bottom wall 36 thereof. An umbrella valve 17 is located at inlet 15 and operates by passively opening due to the head pressure differences in the fuel tank 12 and reservoir 14, and closing when head pressure in reservoir 14 exceeds pressure in fuel tank 12. Valve 17 is required for initial vehicle starts to get the fuel into the reservoir before the system is primed.
In the fully assembled condition of the MFR 10, all electrically conductive parts are grounded through pump 90 to which conductors 102, 106 attach as explained above. In the preferred embodiment, this is accomplished through mutual contact of the conductive parts. Thus, retainer 76 (including integral tubes 42, 44), which itself is made of an electrically conductive material, makes contact with the pump metal shell 92 and is therefore both conductive and grounded. Jet pump 46 is also formed of an electrically conductive material and makes contact with tube 42. Jet pump 46 is therefore also both conductive and grounded. Fuel filter 93 includes a conductive outer shell and end cap 95 which contacts the retainer 76. Filter 93 is therefore also both conductive and grounded. The fuel conduit and connectors 118, 120, 124, 116 and 122 are also all formed of a conductive material and, since they all make contact with fuel filter end cap 95, are all both conductive and grounded. All required and appropriate electrical grounding is therefore maintained by MFR 10.
