Check valve for internal combustion engine fuel tank filler pipe

Abstract: A fuel tank and filler system for an internal combustion engine includes a fuel tank (14), a filler pipe (12) extending into the fuel tank (14), and a check valve (10) comprising a collapsible, normally open tube secured around the outlet (16) of the fuel filler pipe (12) within the tank (14). Fuel entering the tank (14) passes through the filler pipe (12) and collapsible tube (10) unimpeded. The collapsible tube (10) has sufficient flexibility, however, to collapse upon itself in the event that fuel begins to flow outwardly through the filler pipe (12), thereby preventing fuel from leaving the tank (14) through the filler pipe(12).

Description: Automotive fuel system designers have used a variety of structures for preventing the backflow of fuel from fuel tank filler pipes. These devices are generally held closed by a spring, a counterweight, or, in the case of a duckbill device, the inherent stiffness of the material from which the device is constructed. Unfortunately, each of these devices introduce a restriction into the path of fuel moving through the filler pipe. And, such devices are costly and may be subject to functional problems such as sticking. There has been a marked need, therefore, for a simple, rugged device for preventing backflow of fuel through fuel tank filler pipes, while at the same time allowing higher fuel fill rates. U.S. 4,760,933 discloses a duckbill type check valve according to the preamble of claim 1 for controlling backflow from the filling orifice of a fuel tank. The duckbill functions as a resilient valve which is normally closed, but which opens when pressure is created in the filler pipe by a column of fuel as well as by the insertion of a fuel nozzle. It has been found, however, that duckbills having sufficient rigidity to prevent backflow have the undesirable trait described above of limiting the flow of fluid into the tank such that rapid filling is not possible. With a view to mitigating the foregoing disadvantages, the present invention provides a fuel tank and filler system for an internal combustion engine, comprising a fuel tank, a filler pipe extending into the fuel tank and having an outlet situated within the tank, and a backflow controller secured to the outlet of the fuel filler pipe; wherein the backflow controller comprises a normally open valve means for allowing fuel to enter the tank through the filler pipe and for blocking fuel from leaving the tank through the filler pipe. Preferably, the backflow controller comprises a collapsible film membrane formed into a tube. Advantageously, the collapsible tube may be formed as a skirt of a thin film membrane that extends to within a few centimetres of the bottom of the fuel tank. It is an advantage of the present invention that fuel may easily be introduced into the tank below the liquid level. This minimises the aeration of fuel within the tank, thereby minimising the quantity of fuel vapour generated during filling. The invention will now be described further by way of example, with reference to the accompanying drawings, in which: Figure 1 is a schematic representation of a fuel tank and filler system of the invention, showing the check valve in its normally open position, Figure 2 is a schematic representation similar to Figure 1, but showing the check valve in its normally open position, Figure 3 is a sectional view of a fuel filler pipe and check valve, Figure 4 is a plan view of a filler pipe grid taken along the line 4-4 of Figure 2. As shown in Figure 1, a fuel filler pipe, 12, having a cap, 18, and an outlet, 16, extends into a fuel tank, 14. A collapsible thin film check valve 10 is secured around outlet 16 and extends further into fuel tank 14. During refuelling, fuel flows through fuel filler pipe 12 to outlet 16, where the fuel enters check valve 10. Fuel then flows unimpeded through cylindrical check valve 10 and into the main volume of tank 14. Because check valve 10 is normally open, fuel is free to flow unrestricted through check valve 10 into tank 14. This permits high flow rates without annoying pump nozzle cut-off. It has been determined that aeration of the fuel within tank 14 will be minimised if the bottom of check valve 10 is brought to within a few centimetres of the bottom of tank 14. This will help to prevent the generation of excessive amounts of fuel vapour during refuelling. Figures 3 and 4 show additional details of check valve 10, which preferably comprises either a seamless or a wrapped skirt type of cylindrical tube of flexible, substantially impermeable material such as polytetrafluoroethylene film sold under the trademark "Tefzel". It has been determined that a cylinder formed of material having a thickness of approximately 1 millimetre performs satisfactorily as a check valve. As shown in Figure 3, check valve 10 may be attached to outlet 16 by means of a band, 22, which clamps check valve 10 to the filler pipe. Those skilled in the art will appreciate in view of this disclosure that other types of attachment means could be employed for fastening check valve 10 to filler pipe 12. Also, different types of tube cross sections materials are available for practising the present invention. Figure 4 illustrates a grid, 20, extending across filler pipe outlet 16. Grid 20 prevents check valve 10 from moving into fuel filler tube 12 while in the collapsed state. As shown in Figure 2, when the vapour pressure within fuel tank 14 is greater than atmospheric pressure, the removal of cap 18 may be accompanied by the onset of reverse fuel flow. In other words, fuel may begin to flow outwardly through fuel filler pipe 12. In this situation, check valve 10 serves as a backflow controller by collapsing upon itself so as to block the fuel from leaving the tank through the fill pipe. Figure 2 thus shows check valve 10 collapsed upon itself so as to prevent the backflow of fuel through fuel filler pipe 12. Check valve 10 responds to reverse flow by collapsing before any significant volume of fuel has flowed into filler pipe 12. Because check valve 10 has low mass and high flexibility, fuel flowing in the reverse direction quickly collapses the check valve.

Claims: A fuel tank and filler system for an internal combustion engine, comprising: a fuel tank (14), a filler pipe (12) extending into the fuel tank and having an outlet (16) situated within the tank (14), and a backflow controller (10) secured to the outlet (16) of the fuel filler pipe (12); characterised in that said back flow controller comprises a normally open valve means (10) for allowing fuel to enter the tank (14) through the filler pipe (12) and for blocking fuel from leaving the tank (14) through the filler pipe (12). A fuel tank and filler system as claimed in Claim 1, wherein said backflow controller comprises a collapsible film membrane formed into a tube (10). A fuel tank and filler system as claimed in Claim 2, wherein the tube (10) constituting the check valve extends to within a few centimetres of the bottom of the tank (14). A fuel tank and filler system as claimed in Claim 2 or 3, further comprising means (20) for preventing the collapsible tube (10) from being drawn into the fuel filler pipe (12) A fuel tank and filler system as claimed in Claim 4, wherein said means for preventing the collapsible tube (10) from being drawn into the fuel filler pipe (12) comprises a grid (20) extending across the outlet (16) of the fuel filler pipe (12). A fuel tank and filler system as claimed in any preceding claim, wherein said collapsible tube (10) comprises a substantially impermeable cylinder.

Inventors: GRYC WILLIAM STANLEY, GRYC, WILLIAM STANLEY
Applicants: FORD MOTOR CO, FORD WERKE AG, FORD MOTOR COMPANY, FORD MOTOR COMPANY LIMITED, FORD-WERKE AKTIENGESELLSCHAFT
Application year: 1993
Main classification: B60K15
IPC codes: B60K15