FUEL PUMP APPARATUS

Abstract: A fuel pump apparatus (20) for maintaining fuel flow when the surface of the fuel in a fuel tank (l0) is below a minimum level. The fuel pump apparatus includes a reservoir (54) in the fuel tank and a pump (60) in the reservoir. A motor in the pump drives a first pump (78) which draws fuel from a secondary chamber (l29) of the pump and discharges it to the engine. The motor also drives a second pump (76) which draws fuel from the tank through a primary chamber (l36) and discharges it to the secondary chamber. The excess of fuel discharged by the second pump over the first pump is discharged through a flow orifice (l32) in the pump to the reservoir. At fuel levels below the minimum, a float (l48) controlled solenoid (l56) closes an inlet port (l42) to the primary chamber causing fuel to back-flow through the flow orifice to the secondary chamber to supply the first pump.

Description: This invention relates generally to automotive fuel apparatus and, more particularly, to fuel pump apparatus for maintaining fuel flow when tank fuel level temporarily recedes below a predetermined minimum level. Automotive fuel injectors require a constant supply of pressurized fuel from the fuel pump. Consequently, fuel pump intakes are usually located very low in the fuel tank with baffles provided to minimize the likelihood that the intake will be exposed during cornering or other vehicle manoeuvres which tend to displace fuel in the fuel tank. In a more elaborate, prior art arrangement described in US Patent No 3,443,5l9, a reservoir is provided within the fuel tank and a submerged fuel pump is disposed in the reservoir. The fuel pump has an electric motor which drives the impeller of one pump which draws from the fuel tank and discharges directly into the reservoir at one flow rate. The electric motor simultaneously drives another pump which draws only from the reservoir and discharges fuel to the fuel injection apparatus at a flow rate which is less than the flow rate of the one pump. The fuel injectors are thus continuously supplied with fuel as long as there is fuel in the reservoir regardless of whether or not the intake of the one pump is submerged. A fuel pump apparatus according to this invention is a new and improved alternative to the prior art arrangement just described. Further, the present invention can provide a submerged fuel pump having superior vapour separation capability during normal operation which is also protected against transient fuel starvation when the level of fuel in the tank momentarily drops below the pump intake such as might occur when the vehicle rounds a corner at high speed. According to the present invention, fuel pump apparatus for an engine of an automotive vehicle having a fuel tank thereon defining a fuel chamber therein comprises a reservoir chamber fuel pump apparatus for an engine of an automotive vehicle having a fuel tank thereon defining a fuel chamber therein, the fuel pump apparatus including a reservoir chamber mountable within the fuel chamber; a fuel pump in the reservoir chamber having an electric motor simultaneously driving at a normal operating speed of the electric motor a first pump having an inlet port and a discharge port and a second pump having an inlet port and a discharge port, the first pump at the normal operating speed of the electric motor providing a first fuel flow rate and the second pump at the normal operating speed of the electric motor providing a second fuel flow rate exceeding the first fuel flow rate, and the discharge port of the first pump being connectable to the engine; a secondary chamber connected to the inlet port of the first pump and connected to the discharge port of the second pump; a primary chamber having an inlet port connectable with the fuel chamber, the primary chamber and the inlet port of the second pump being connected so that the second pump can normally draw fuel from the fuel chamber through the primary chamber and discharge fuel to the secondary chamber; a flow orifice between the secondary chamber and the reservoir chamber allowing flow of fuel in opposite directions between the secondary and the reservoir chambers, the excess of the second fuel flow rate of the second pump over the first fuel flow rate of the first pump being discharged through the flow orifice from the secondary chamber to the reservoir chamber; and level responsive means connected to the primary chamber, responsive to the level of the surface of the fuel in the fuel chamber and operable to close the inlet port of the primary chamber when the surface of the fuel is below a predetermined minimum level, the first pump thereupon creating a vacuum in the secondary chamber so that fuel back-flows through the flow orifice from the reservoir chamber to the secondary chamber to maintain a supply of fuel at the inlet port (of the first pump. The fuel pump apparatus according to this invention is a new and improved reservoir-type system wherein a fuel pump submerged in an in-tank reservoir includes one pump which normally draws fuel from the main tank through a primary chamber and discharges the fuel at one flow rate to a secondary chamber and further includes another pump which draws fuel from the secondary chamber and discharges it to the fuel injectors at a flow rate less than the flow rate of the one pump, the excess fuel from the one pump being discharged from the secondary chamber into the reservoir to maintain the reservoir in a fuel-filled condition. The primary chamber has an inlet port which is open when tank fuel level is above a pre­ determined minimum and is sealed by level responsive valving at lower fuel levels, the other pump thereupon creating a vacuum in the secondary chamber so that fuel back-flows from the reservoir into the secondary chamber. In a preferred embodiment of the fuel pump apparatus according to this invention, the primary chamber is opened and closed by a solenoid operated valve responsive to tank fuel level and the one pump is an open vane regenerative pump which, in addition to supplying fuel to the secondary chamber, also separates vapour from the fuel so that the other pump is normally supplied with only vapour-free fuel. The present invention is now described, by way of example, with reference to the accompanying drawings, in which:- Figure l is a schematic elevational view of a fuel tank of an automobile having a fuel pump apparatus according to this invention disposed therein; Figure 2 is an enlarged view of a portion of Figure l showing the fuel pump apparatus according to this invention; Figure 3 is an enlarged, partially broken away view of a portion of Figure 2; and Figure 4 is a sectional view taken generally along the plane indicated by lines 4-4 in Figure 3. Referring now to Figures l and 2 of the drawings, a fuel chamber 8 of a fuel tank l0 of an automobile is defined on top by an upper panel l4 of the fuel tank and on the bottom by a lower panel l6 of the fuel tank. The upper panel l4 has a circular aperture l8 therein, Figure 2, through which a fuel pump apparatus 20 of the reservoir type according to this invention is introduced into the fuel chamber 8 and whereat the fuel pump apparatus is secured to the fuel tank l0. As seen best in Figure 2, the fuel pump apparatus 20 includes a reservoir housing 22. The reservoir housing 22 includes a cylindrical wall portion 24 which is open at a lower edge 26 and a circular upper end wall 28 integral with the cylindrical wall portion 24. A coil spring 30 bears at one end against a seat 32 and at the other end against the circular upper end wall 28 around a pilot flange 34 on the latter. The seat 32 is connected to a closure plate 36 through a plurality of posts 38. The peripheral edge of the closure plate 36 overlaps the radially innermost edge of an annular attaching plate 40 and is separated from the latter by an elastomeric ring 42. Fasteners, not shown, clamp the closure plate 36 to the annular attaching plate 40 and squeeze the elastomeric ring 42 therebetween so that a vapour tight seal is defined between the closure plate and the annular attaching plate. Additional fasteners, not shown, secure a radially outer portion of the annular attaching plate 40 to the upper panel l4 of the fuel tank l0. A plurality of tubes traverse the closure plate 36 through appropriate vapour-tight grommets or gaskets, the tubes including a main fuel supply tube 44, a fuel return tube 46, a vapour purge tube 48 and an electrical conduit 49. The main fuel supply tube 44 is typically connected to the fuel injection apparatus of the vehicle, not shown, to supply fuel to the latter. The fuel return tube 46 is typically connected to an appropriate overflow device in the fuel injection apparatus and conducts excess fuel from the fuel injection apparatus back to the fuel tank l0. The vapour purge tube 48 is typically connected to a charcoal canister or like device which captures fuel vapours when the vehicle is parked. The electrical conduit 49 typically has conductors therein for energizing the electric motor of the fuel pump apparatus. With continued reference to Figure 2, an end assembly 50 of the fuel pump apparatus 20 includes a circular wall 52 which closes the lower end of the cylindrical wall portion 24. The circular wall 52 cooperates with the upper end wall 28 and the cylindrical wall portion 24 in defining a reservoir chamber 54 within the fuel chamber 8. Inboard of the closure plate 36, the main fuel supply tube 44 extends into the reservoir chamber 54 through a flanged aperture 56 in the circular upper end wall 28. The inner end of the fuel return tube 46, not shown, likewise extends into the reservoir chamber 54. The inner end of the main fuel supply tube 44 is connected to an appropriate fuel discharge nipple 58 on an electric fuel pump 60. A perforated partition 62 in the reservoir chamber 54 supports the upper end of the electric fuel pump 60 and maintains the latter in a vertical orientation. At the lower end of the electric fuel pump 60, a cylindrical flange 64 on an inlet body 66 of the electric fuel pump, Figure 3, is connected to the circular wall 52 through a cushioning bushing 68 in an aperture 70 in the circular wall. The cushioning bushing 68, in addition to supporting the lower end of the electric fuel pump 60, isolates the latter from the reservoir housing 22 for vibration and noise control. Appro­ priate electrical conductors in the electrical conduit 49 are connected to appropriate terminals on the electric fuel pump 60, not shown, whereby operation of the electric fuel pump is synchronized with the state of the ignition apparatus of the vehicle. Referring particularly to Figures 2, 3, and 4, the electric fuel pump 60, except as otherwise indicated, is generally conventional and includes a tubular, cylindrical housing 74 in which are disposed a low pressure regenerative pump 76, a roller vane pump 78, of the high-pressure, positive displacement type, and an electric motor, not fully illustrated, for simultaneously driving both the low pressure regenerative pump and the roller vane pump. The electric motor includes a cylindrical flux ring 80 within the tubular cylindrical housing 74 and an armature shaft portion 82. The armature shaft portion 82 is rotatable about a longitudinal axis of the electric fuel pump 60 as a unit with a drivefork 86. Roller vane pump 78 defines a first pump, and low pressure regenerative pump 76 defines a second pump. The roller vane pump 78 includes a circular discharge plate 88 abutting an edge 89 of cylindrical flux ring 80. The circular discharge plate 88 has a discharge port 90 opening into an internal chamber 92 of the tubular cylindrical housing 74 around the armature shaft portion 82. The roller vane pump 78 further includes a circular inlet plate 94 having an inlet port 96 therein and a pump ring 98 captured between the circular discharge plate 88 and the circular inlet plate 94. These two plates 88,94 and the pump ring 98 are rigidly interconnected by axially extending fasteners, not shown. An eccentric rotor l00 of the roller vane pump 78 is disposed within the pump ring 98 and is drivingly connected to the drivefork 86. A plurality of cylindrical rollers l02 are carried in appropriate pockets of the eccentric rotor l00 and ride against an inner surface l03 of the pump ring 98 when the eccentric rotor is rotated by the electric motor through the drivefork 86. The spaces between the cylindrical rollers l02 define variable volume chambers which operate to pump fuel from the inlet port 96 to the discharge port 90 when the eccentric rotor rotates. At a normal operating speed of the electric motor, the roller vane pump 78 provides fuel at a first predetermined fuel flow rate at the discharge port 90 sufficient to meet all of the fuel requirements of the fuel injection apparatus. Referring to Figures 3 and 4, the low pressure regenerative pump 76 includes, in addition to the inlet body 66, a discharge body l04, which is generally cylindrical, disposed between the inlet body 66 and the circular inlet plate 94 of the roller vane pump 78. An end surface l06 of the discharge body l04 is disposed in a plane perpendicular to the axis of rotation of the armature shaft portion 82 and abuts a corresponding end surface l08 on the inlet body 66. A key ll0 integral with the discharge body l04 extends into an appropriate notch in the inlet body 66 whereby relative rotation between the inlet and discharge bodies 66,l04 is prevented. A shallow annular groove ll2 in the inlet body 66 is aligned with a deeper annular groove ll4 in the discharge body l04 and cooperates with the latter in defining an annular pumping chamber ll5 around the peripheral edge of an open vane, regenerative pump impeller ll6. The regenerative pump impeller ll6 is loosely captured between the inlet and discharge bodies 66,l04 and is drivingly connected to the distal end of armature shaft portion 82. An inlet port ll8 in the inlet body 66 provides communication between the interior of the cylindrical flange 64 on the inlet body and the annular pumping chamber ll5. A discharge port l20 in the discharge body l04 defines a channel between the annular pumping chamber ll5 and a cavity l2l in an end wall l22 of the discharge body. The cavity l2l faces, and is closed by, the circular inlet plate 94 of the roller vane pump 78 and overlies the inlet port 96 to the latter. Appropriate stripper walls, not shown, on the inlet and discharge bodies 66 and l04 operate in conventional fashion to prevent leakage of fuel from the discharge port l20 back to the inlet port ll8 of the low pressure regenerative pump 76. A flapper valve l23 on the inlet body 66 loosely seals a vapour discharge port l24 and permits escape of vapours from the annular pumping chamber ll5 while preventing both vapour and liquid back-flow in the opposite direction. Vapours separate in the low pressure regenerative pump 76 as the regenerative pump impeller ll6 rotates because the liquid fuel, being heavier than the vapours, is propelled radially out and forces the vapours in the opposite direction toward the vapour discharge port l24. Regenerative pump impeller ll6 and vapour discharge port l24 define vapour separating means. At the normal rotating speed of the electric motor, the low-­ pressure regenerative pump 76 provides vapour-free fuel to the cavity l2l at a second fuel flow rate which exceeds the first fuel flow rate of the roller vane pump 78 so that when the electric motor is on, the low pressure regenerative pump 76 always provides more fuel at the inlet port 96 than the roller vane pump 78 discharges. As seen best in Figures 3 and 4, the low pressure regenerative pump 76 departs from heretofore known pump structures in that the outer cylindrical surface of the discharge body l04 has an external groove l26 therein which extends for less than the axial length of the outer cylindrical surface. When the discharge body l04 is disposed within the tubular cylindrical housing 74, the external groove l26 cooperates with the tubular cylindrical housing in defining an annular chamber around the discharge body which communicates with the cavity l2l through a radial slot l28 in the end wall l22 of the discharge body. The cavity l2l, the radial slot l28 and the external groove l26 together form a secondary chamber l29 between the discharge port l20 of the low pressure regenerative pump 76 and the inlet port 96 of the roller vane pump 78. A flow orifice l32 in the tubular cylindrical housing 74 provides communication between the secondary chamber l29 and the reservoir chamber 54. Referring to Figures 2 and 3, the end assembly 50 has a circular cover l34 thereon which cooperates with the circular wall 52 in defining a primary chamber l36. A flexible screen l38 is attached to a flange l40 on the circular cover l34 and rests against the lower panel l6 of the fuel tank l0. An inlet port l42 in the circular cover l34 inside the flange l40 normally permits fuel to flow from the fuel chamber 8 in the fuel tank l0, through the flexible screen l38, and into the primary chamber l36. Fuel in the primary chamber l36 flows within the cylindrical flange 64 of the inlet body 66 and into the inlet port ll8 of the low pressure regenerative pump 76. The coil spring 30 bearing against the reservoir housing 22 cooperates with the natural resilience of the flexible screen l38 in supporting the fuel pump apparatus 20 in the fuel chamber 8 in the fuel tank l0. A float housing l44 integral with the end assembly 50 has an internal chamber l46 in which a float l48 is slidably disposed. A perforated retainer l50 at the lower end of the internal chamber l46 keeps the float l48 in the internal chamber but permits fuel to enter from below so that the float l48 can ride on the surface of the pool in the fuel chamber 8 when the surface of the pool is at the level of the float housing l44. A Reed switch l52 is disposed within a centre tube l54 of the float housing l44 and is responsive to the position of the float l48. When the surface of the pool in the fuel chamber 8 exceeds a predetermined minimum level above the lower panel l6 the float l48 is above the perforated retainer l50 and the Reed switch l52 is open. When the surface of the pool recedes below the predetermined minimum level, the float l48 moves down toward the perforated retainer l50 and closes the Reed switch l52. As seen best in Figure 2, the Reed switch l52 in the float housing l44 controls a solenoid l56 mounted on circular wall 52. The solenoid l56 has a linearly shiftable armature l58 which extends down through the inlet port l42 of the primary chamber l36 and carries at its distal end a valve plate l60. When no current is supplied to the solenoid l56, i.e., when the solenoid is deenergized, the valve plate l60 is positioned by the linearly shiftable armature l58 in an open position, Figure 2, remote from the inlet port l42. When current is supplied to the solenoid l56 the linearly shiftable armature l58 is withdrawn into the solenoid and positions the valve plate l60 in a closed position sealing the inlet port l42. Accordingly, with the Reed switch l52 connected to a power source and to the solenoid l56, when the surface of the pool in the fuel chamber 8 of the fuel tank l0 exceeds the predetermined minimum level the Reed switch l52 is open, the solenoid l56 is deenergized, and the inlet port l42 is open. Conversely, when the surface of the pool is below the predetermined minimum level, the Reed switch l52 is closed, the solenoid l56 is energized, and the valve plate l60 seals the inlet port l42. Float housing l44, solenoid l56, linearly shiftable armature l58, valve plate l60, Reed switch l52 and float l48 define level responsive means. The fuel pump apparatus 20 operates as follows. As the fuel chamber 8 in the fuel tank l0 is filled from empty the surface of the pool therein rises from the lower panel l6. Normally, the ignition is off during the fueling process so that the solenoid l56 is deenergized and the inlet port l42 is open. Accordingly, the fuel rises up through the inlet port l42 and fills the primary chamber l36. Simultaneously, the float l48 moves upward until it engages the upper surface of the internal chamber l46 and is then submerged as fuel filling continues. When the ignition is turned on the electric motor in electric fuel pump 60 is energized and drives both the eccentric rotor l00 of the roller vane pump 78 and the regenerative pump impeller ll6 of the low pressure regenerative pump 76. Fuel is drawn from the primary chamber l36 by the low pressure regenerative pump 76 and discharged into the secondary chamber l29. Roller vane pump 78 draws fuel from the secondary chamber l29 and discharges it to the main fuel supply tube 44 for delivery to the fuel injection apparatus of the vehicle. The excess of fuel delivered to the secondary chamber l29 by the low pressure regenerative pump 76 over the amount drawn off by roller vane pump 78 is discharged into the reservoir chamber 54 through the flow orifice l32 to fill the reservoir chamber with fuel. Simultaneously, excess fuel not consumed at the engine of the vehicle pours into the reservoir chamber 54 from fuel return tube 46. A plurality of vents l62 in the circular upper end wall 28 permit air and vapour escape as the fuel fills the reservoir chamber 54 and also permits any excess fuel in the reservoir chamber to escape into the fuel chamber 8. As the quantity of fuel in the fuel chamber 8 diminishes, the surface of the pool therein approaches the predetermined minimum level. If the vehicle experiences an extended cornering manoeuvre during which the fuel in the fuel tank l0 migrates to one side or the other the surface of the pool on which the float l48 rides may recede below the predetermined minimum value. At that instant, the Reed switch l52 closes, the solenoid l56 is energized, and valve plate l60 is shifted to the closed position sealing the inlet port l42. With the primary chamber l36 thus sealed, low pressure regenerative pump 76 no longer supplies fuel at the second fuel flow rate described above to the secondary chamber l29. However, because roller vane pump 78 continues to operate normally, a vacuum is created in the secondary chamber l29 and fuel is drawn in back-flow fashion from the reservoir chamber 54, through the flow orifice l32, through the external groove l26 and the radial slot l28, and then into the inlet port 96 of the roller vane pump. The supply of fuel to the roller vane pump 78 thus continues uninterrupted even though the inlet port ll8 of the low pressure regenerative pump 76 is effectively blocked. At the end of the cornering manoeuvre, the surface of the pool in the fuel chamber 8 rises above the predetermined minimum level and the Reed switch l52 opens to deenergize the solenoid l56. The valve plate l60 then shifts to the open position and low pressure regenerative pump 76 resumes normal operation with fuel being supplied from the primary chamber l36 and the excess being directed to the reservoir chamber 54 through the flow orifice l32 to replenish the amount drawn off during the period when the valve plate l60 was in the closed position. While the fluid level responsive means for opening and closing the primary chamber l36 of the preferred embodiment include the Reed switch l52 and the (electrically operated) solenoid l56, other arrangements are possible. For example, the Reed switch and solenoid of the preferred embodiment could be replaced by a mechanical float arrangement, not shown, wherein a float on the surface of the pool in the fuel chamber 8 closes and opens the inlet port to the primary chamber directly as the surface of the pool rises and falls relative to the predetermined minimum level.

Claims: 1. Fuel pump apparatus (20) for an engine of an automotive vehicle having a fuel tank (l0) thereon defining a fuel chamber (8) therein, the fuel pump apparatus including a reservoir chamber (54) mountable within the fuel chamber; a fuel pump (60) in the reservoir chamber having an electric motor simultaneously driving at a normal operating speed of the electric motor a first pump (78) having an inlet port (96) and a discharge port (90) and a second pump (76) having an inlet port (ll8) and a discharge port (l20), the first pump at the normal operating speed of the electric motor providing a first fuel flow rate and the second pump at the normal operating speed of the electric motor providing a second fuel flow rate exceeding the first fuel flow rate, and the discharge port (90) of the first pump being connectable to the engine; a secondary chamber (l29) connected to the inlet port (96) of the first pump and connected to the discharge port (l20) of the second pump; and a primary chamber (l36) having an inlet port (l42) connectable with the fuel chamber, the primary chamber and the inlet port (ll8) of the second pump being connected so that the second pump can normally draw fuel from the fuel chamber through the primary chamber and discharge fuel to the secondary chamber; characterised by a flow orifice (l32) between the secondary chamber and the reservoir chamber allowing flow of fuel in opposite directions between the secondary and the reservoir chambers, the excess of the second fuel flow rate of the second pump over the first fuel flow rate of the first pump being discharged through the flow orifice from the secondary chamber to the reservoir chamber; and by level responsive means (l44,l56,l58,l60) connected to the primary chamber, responsive to the level of the surface of the fuel in the fuel chamber and operable to close the inlet port (l42) of the primary chamber when the surface of the fuel is below a predetermined minimum level, the first pump thereupon creating a vacuum in the secondary chamber so that fuel back-flows through the flow orifice from the reservoir chamber to the secondary chamber to maintain a supply of fuel at the inlet port (96) of the first pump. 2. Fuel pump apparatus as claimed in claim l wherein the second pump is an open vane regenerative pump (76) having vapour separating means (ll6,l24) therein operative to separate vapours from fuel drawn from the primary chamber (l36) so that only essentially vapour-free fuel is delivered to the secondary chamber (l29) and to the inlet port (96) of the first pump (78). 3. Fuel pump apparatus as claimed in claim l or claim 2 wherein the level responsive means includes a float housing (l44) exposed to the fuel in the fuel chamber (8); a float (l48) in the float housing riding on the surface of the fuel in the fuel chamber; a solenoid (l56) having a linearly shiftable armature (l58); a valve member (l60) connected to the linearly shiftable armature and movable thereby between an open position remote from the inlet port (l42) of the primary chamber (l36) and corresponding to a deenergized state of the solenoid, and a closed position closing the inlet port of the primary chamber and corresponding to an energized state of the solenoid; and an electrical switch (l52) connected to the solenoid and responsive to the position of the float, the float actuating the electric switch to energize the solenoid when the surface of the fuel in the fuel chamber is below the predetermined minimum level and to deenergize the solenoid when the surface of the fuel in the fuel chamber is above the predetermined minimum level.

Inventors: FALES, IVAN DOUGLAS, ROTH, ROBERT ALBERT
Applicants: GENERAL MOTORS CORPORATION
Application year: 1987
Main classification: F02M37
IPC codes: F02M37, F04C15, F04C14, F04C11