MODULAR FUEL DELIVERY SYSTEM

Abstract: A canister (22) with an electric fuel pump therein is connected to a cover (46) for an access port (18) through which the canister (22) is installed on a fuel tank (10) of an automobile by three hollow struts (76A,76B,76C). Each strut (76A,76B,76C) has a first end (78) press-fitted into a socket (70) on the cover (46) and is telescopically received in a respective bore (82) in the canister (22). Coil springs (88A,88B,88C) around each strut (76A,76B,76C) urge relative separation between the strut (76A,76B,76C) and the cover (46) and a flare at a second end (80) of each strut (76A,76B,76C) defines a stop to limit said relative separation. A passage (74) in the cover (46) from a return fuel connection (60) on an exposed side of the cover (46) to one of the sockets (70) conducts low-pressure return fuel to the hollow strut (76A) press-fitted therein. The return fuel flows back to the canister (22) through that hollow strut (76A).

Description: This invention relates to modular fuel delivery systems for automobiles as specified in the preamble of claim 1, for example as disclosed in US-A-4,694,857. In the modular fuel delivery system disclosed in US-A-4,694,857, a biasing means between the canister and the cover of the system is provided by a piston-and-cylinder arrangement in a fuel delivery assembly of the system which applies a pressure bias between the canister and the cover which is derived from the output side of a fuel pump in the system. Manufacturing economies are achieved by grouping several functionally-related components into a module which is handled and installed as a unit. In automotive fuel systems, for example, modular fuel delivery systems have been proposed for direct installation on a fuel tank. Such modules are typically inserted through a hole in the top of the fuel tank and usually include a reservoir canister, a pump, a fuel level transducer attached to the canister, a cover, and elements for attaching the canister to the cover and for conducting high-pressure fuel and low-pressure fuel from the canister to the cover. The pump is located inside the canister to avoid momentary fuel starvation thereof during a vehicle in which it is mounted undergoing turns and the like movements when the fuel level in the fuel tank is low, and the cover is clamped to the top of the tank to close the hole through which the module is installed. Springs between the cover and the canister bias the latter against a bottom wall of the fuel tank so that fuel level is referenced from the bottom wall of the fuel tank. A modular fuel delivery system according to this invention incorporates novel connecting structure between the cover and the canister. A modular fuel delivery system according to the present invention is characterised by the features specified in the characterising portion of claim 1. This invention is a new and improved automotive modular fuel delivery system including a reservoir canister for installation in a fuel tank of a vehicle, an electric pump in the canister, a cover for closing an access hole in a top wall of the fuel tank, and a return fuel connector on the cover to which low-pressure excess fuel from the engine is conveyed. The fuel delivery system according to this invention further includes three hollow struts each having an upper end press-fitted into a respective one of three symmetrically-arrayed sockets in the cover and a lower end telescopically received in a respective one of three similarly symmetrically-arrayed bores in the canister. Coil springs are disposed around each strut and bias the canister away from the cover, relative separation between the canister and cover being limited by interference between the canister bores and stops at the bottom ends of the struts. The return fuel connector on the cover has an internal passage to one of the strut sockets so that return fuel is conveyed to the canister through the hollow strut. Each strut further includes an orifice near the cover which prevents backflow from the canister and which defines a flex-point where flexure of the strut under extraordinary column or beam loading is concentrated. The invention and how it may be performed are hereinafter particularly described 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 system according to this invention; Figure 2 is an enlarged perspective view of only the modular fuel delivery system according to this invention; and Figure 3 is a partially broken-away perspective view of a portion of Figure 2. As seen best in Figures 1 and 2, a fuel tank 10 of an automobile, not shown, defines a fuel chamber 12 bounded on top by a top wall 14 of the tank and at the bottom by a bottom wall 16 of the tank. The top wall 14 has a hole providing an access port 18 therein for installation of a modular fuel delivery system 20 according to this invention. The fuel delivery system 20 includes a reservoir canister 22 having a retainer top 24 and a cylindrical wall 26 with a flat side 28. A metal bracket 30 is rigidly attached to the canister 22 parallel to the flat side 28. A fuel level transducer 32 is rigidly attached to the bracket 30 between the latter and the flat side 28 and includes a float 34 on an arm 36 which pivots with changes in the surface level of the fuel in the fuel chamber 12. The transducer 32 may be connected to the bracket at various locations to accommodate different fuel tanks. A first high-pressure connector 38, Figure 2, is attached to the top 24 in a depression 40, see Figure 3, in the latter. A discharge port of a conventional electric fuel pump, not shown, in the canister 22 communicates with the first high-pressure connector 38 below the top 24. A lower end of an intermediate hose 42 is pressed into a barbed end of the connector 38 above the top 24. The electric pump is connected to the electrical system of the automobile through an in-tank portion 44 of the wiring harness of the vehicle. When the ignition of the vehicle is switched on, the pump pumps fuel from inside the canister into the intermediate hose 42. The fuel delivery system 20 further includes a cover 46 for closing the hole 18 in the top wall 14 of the tank. The cover 46 is a flat plastics disc having an integral depending flange 48 therearound. The disc has an annular shoulder 50 positioned radially outboard of the depending flange which seats against a seal, not shown, on the top wall 14 of the tank around the hole 18. Conventional means, not shown, clamp the cover 46 to the top wall 14 of the tank. The cover has a moulded-in, or otherwise sealingly attached, electrical connector 52 which defines a junction between the in-tank portion 44 of the wiring harness and an outside portion 54, Figure 2, of the wiring harness. The cover 46 has a plurality of moulded-in fluid connectors including a high-pressure connector 56, a vapor connector 58, and a low-pressure, return fuel connector 60. On the side of the cover facing the canister 22, the high-pressure connector 56 is attached to an upper end of the intermediate hose 42. On the opposite, exposed side of the cover, the high-pressure connector 56 has a barbed, tubular end 62 for attachment of a hose, not shown, through which the high-pressure fuel discharged from the pump to the intermediate hose 42 is transported to an engine of the vehicle. On the side of the cover 46 facing the canister 22, the vapor connector 58 is attached to a valve 64, Figure 2, which is open to the vapor space in the fuel chamber 12 above the fuel in the chamber. On the exposed side of the cover, the vapor connector 58 has a barbed, tubular end 66 for attachment of a hose, not shown, through which the vapors from the tank are transported to a charcoal canister, not shown. On the exposed side of the cover 46, the return fuel connector 60 has a barbed, tubular end 68 for attachment of a hose, not shown, through which low-pressure excess fuel from the engine is directed back to the fuel tank. On the side of the cover 46 facing the canister 22, the return fuel connector 60 has a cylindrical socket 70 in a boss 72 of the cover, see Figure 3. The socket 70 communicates with the tubular end 68 through a passage 74 of the return fuel connector 60. The modular fuel delivery system 20 further includes a plurality of identical hollow struts 76A-C. Each strut has an upset, rounded upper end 78 and a flared lower end 80. The strut 76A is telescopically received in a cylindrical bore 82, Figure 3, in a boss 84 located on an underside of the top 24 of the canister 22 within the cylindrical wall 26 of the latter. The upper end 78 of the strut 76A is press-fitted into the socket 70 of the return fuel connector 60, the rounded shape of the upper end 78 imparting a degree of angular flexibility to the joint between the strut and the cover so that the strut 76A has limited articulation relative to the cover 46. The struts 76B,76C are telescopically received in bores, not shown, in the top 24 of the canister 22 corresponding to the bore 82, the three bores being equally angularly spaced around the top. The upper ends of the struts 76B,76C are press-fitted in moulded-in sockets in the cover, not shown, corresponding to the socket 70, the three sockets likewise being equally angularly spaced around the cover 46. Each strut has a pair of cross-drilled holes 86 therein, Figure 3, below the corresponding socket in which the upper end of the strut is received. Respective ones of a plurality of springs 88A-C are disposed around the struts 76A-C, respectively, between the cover 46 and the top 24 of the canister and urge relative separation therebetween until stops defined by the flared lower ends 80 of the struts interfere with the bosses 84 around the bores 82. The lengths of the struts 76A-C are co-ordinated with the vertical depth of the fuel tank 10 between the top wall 14 and the bottom wall 16 so that the springs 88A-C are compressed when the cover 46 is clamped to the top wall. Accordingly, the springs maintain the canister 22 in contact with the bottom wall 16 so that the fuel level signal from the transducer 32 takes a reference point from the bottom wall 16 of the fuel tank 10. When the ignition of the vehicle is switched on, the fuel pump continuously circulates fuel at high pressure from the canister to the engine and then at low pressure back to the canister through the return fuel connector 60 and the hollow strut 76A. Should a condition exist in which the pressure in the reservoir 22 exceeds the pressure in the return fuel hose or should the canister 22 be filled to capacity, the cross-drilled holes 86 in the strut 76A prevent backflow of fuel by defining orifices through which excess fuel pours directly into the fuel chamber 12. The cross-drilled holes 86 in all of the struts 76A-C also define flex-points on the struts calibrated to concentrate flexure at the holes 86 at predetermined levels of compression and/or bending which might be encountered if the tank 10 is collapsed. The equal angular distribution of the sockets 70 in the cover 46 and the bores 82 in the top 24 is an important feature because it permits the cover to be angularly indexed through three positions relative to the canister. Thus, for example, a single modular fuel delivery system 20 can be used where one fuel tank is used in several different vehicle models having different fuel line routings and possibly even different tank locations. In each instance, the canister 22 assumes the same position relative to the tank so that re-calibration of the transducer 32 is unnecessary, whilst the cover 46 is angularly indexed relative to the canister 22 to achieve the most convenient hose routing.

Claims: A modular fuel delivery system (20) for an installation on a fuel tank (10) of an automotive vehicle, said modular fuel delivery system (20) including a canister (22) for disposition in said fuel tank (10); an electric pump disposed in said canister (22) for pumping fuel therefrom to an engine of said vehicle; and a cover (46) for closing an access port (18) in a wall (14) of said fuel tank (10), said cover (46) having an inside surface facing said canister (22), an exposed surface opposite said inside surface, and a low-pressure return fuel connector (60) on said exposed surface; said modular fuel delivery system (20) including a plurality of hollow struts (76A,76B,76C); a plurality of sockets (70) formed on said inside surface of said cover (46) corresponding in number to the number of said struts (76A, 76B, 76C) and evenly angularly arrayed around said inside surface, each socket (70) housing a first end (78) of a respective hollow strut; and a biasing means between the canister (22) and the cover (46); said struts (76A,76B,76C) forming a telescopic connection between the canister (22) and the cover (46) that allows relative movement between the canister (22) and the cover (46) and results in a second end (80) of each of said struts (76A,76B,76C) being exposed to the interior of said canister (22); and there is a passage (74) defined on said cover (46) from said return fuel connector (60) to one of said sockets (70) so that return fuel flows to the interior of said canister (22) through the corresponding strut (76A) that is housed in said one socket (70), said hollow struts (76A, 76B, 76C) being all identical hollow struts; characterised in that said sockets (70) are symmetrically arrayed around said inside surface of said cover (46); said first end (78) of each of said struts (76A,76B,76C) is press-fitted into a respective one of said sockets (70); said canister (22) is provided with a retainer top (24); a plurality of cylindrical bores (82) are defined in said retainer top (24) corresponding in number to the number of said struts (76A,76B,76C) and symmetrically arrayed around said retainer top (24), said cylindrical bores (82) communicating with the interior of said canister (22) and telescopically receiving therein respective ones of said struts (76A,76B,76C); said biasing means comprises spring means (88A,88B,88C) positioned around each of said struts (76A,76B,76C) between said cover (46) and said retainer top (24) urging relative separation therebetween; and there is a stop at said second end (80) of each of said struts (76A,76B,76C) which is engageable on said retainer top (24) to limit said relative separation between said retainer top (24) and said cover (46). A modular fuel delivery system according to claim 1, characterised in that each of said hollow struts (76A,76B,76C) has a flex-point defined thereon between said cover (46) and said canister (22) which is operative to concentrate flexure of said struts (76A,76B,76C) thereat under extraordinary bending and compression loading of said struts (76A,76B,76C). A modular fuel delivery system according to claim 2, characterised in that each flex-point comprises a pair of cross-drilled holes (86) in each of said struts (76A,76B,76C) adjacent the corresponding socket (70) into which each of said struts (76A,76B,76C) is press-fitted. A modular fuel delivery system according to any one of claims 1 to 3, characterised in that said spring means between said cover (46) and said retainer top (24) comprises coil springs (88A,88B,88C) disposed around respective ones of said hollow struts (76A,76B,76C) and seating at opposite ends thereof on said retainer top (24) and on said cover (46). A modular fuel delivery system according to any one of claims 1 to 4, characterised in that the stop at said second end (80) of each of said hollow struts (76A,76B,76C) comprises a flare at said second end (80) thereof.

Inventors: COHA, TIMOTHY FRANCIS, KOSTELIC, RICHARD FRANK, RASMUSSEN, GREGORY KELLER
Applicants: GENERAL MOTORS CORPORATION
Application year: 1990
Main classification: F02M37
IPC codes: F02M37