Pipes and tubular conduits – Flexible – Distinct layers
Reexamination Certificate
1999-11-12
2001-01-09
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
Flexible
Distinct layers
C138S140000, C138S141000
Reexamination Certificate
active
06170535
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to multi-layered laminate structures which may be used to handle volatile, explosive liquids. In particular, the invention relates to a multi-layered laminated structure useful as a filler pipe for adding hydrocarbon containing fluids such as gasoline to a storage tank as may be carried in a vehicle having an internal combustion engine.
BACKGROUND OF THE INVENTION
Hydrocarbon containing fluids such as gasoline are the most common power source for internal combustion engines. Gasoline must be carried by the vehicle, usually in a fuel tank. The fuel tank is located at some convenient location within the structure of the vehicle. Often the fuel tank is contained within a reinforced area so as to provide crash protection for the fuel tank.
In order to provide a convenient access to the tank, the vehicle is typically fitted with a fuel filler inlet. Thus, there is required a conduit to extend between the fuel filler inlet and the tank. That conduct may be long or short and may be of convoluted configuration depending upon the relative location of the tank and the filler inlet.
Most hydrocarbon containing fuels are relatively volatile. Accordingly, the fuel filler conduit must contain at least one layer to substantially inhibit, if not totally prevent, passage of vapours from the liquid fuel to ambient atmosphere outside the filler pipe.
Previously fuel tanks and fuel filler pipes have been made of metal. However, for cost and other reasons, more recently fuel tanks have been manufactured of plastic materials. Fuel tanks being relatively large hollow structures are particularly suited to be made in blow molding procedures. With the advent of plastic rather than metallic fuel tanks, it is now desirable to use plastic fuel filler pipes.
It is well understood by those familiar with the handling and storage of fuels such as gasoline, that static electricity can be generated during the filling procedure. Static electricity in fuel storage systems is dependent primarily on the rate of fill, the amount of turbulence in the fuel as it passes along the conduit and the amount of charge present in the fuel before contacting the vehicle. As fuel is passed along the conduit there is a good likelihood that a static electricity charge will build up. If that charge is permitted to increase until a spark is generated there is a danger of explosion of fuel vapours. Such explosions can be catastrophic not only to the fuel system but the entire vehicle and those in the vicinity of the vehicle.
In the past when fuel tanks were manufactured from metals and fuel filler pipes were also metallic, the natural conductivity of the metal served to bleed off any static electricity as it was generated thus preventing an increase in charge to the point where there was a spark.
In almost all systems, the part of the filler head which touches the refuelling nozzle is made of a conductive material and that is connected directly to the vehicle ground. This effectively prevents a difference in electrical potential between the refuelling nozzle and the filler head and the vehicle. Thus, there is no spark discharge. However, when a plastic fuel filler pipe is desired, because of the normal insulative value of most plastic resins, there will be no readily available way to bleed off or ground the static electricity which may be built up along the filler pipe itself.
It is also desirable that fuel filler pipes when made of plastic be capable of being joined to related structure. At one end this means connection to the tank. At the other end this conduit will be joined to a filler coupling. Such connection at one or both ends may be made by welding, particularly where two similar thermoplastic materials are involved. Such welding is commonly done by raising the temperature of the two surfaces to be joined and then bringing the two molten surfaces into contact to enable fusion to occur as cooling occurs.
Connections may also be required or desired at points along the conduit and it may be especially desirable that one or more of such connections are electrically connected to assist in bleeding off static electricity.
Thus, there is need for a fuel filler conduit which may be economically manufactured from plastic resins which inhibits the passage of vapours through the conduit to the surrounding atmosphere and which at the same time provides an electrically conductive path sufficient to prevent the build up of static electricity by fuel passing along the conduit.
SUMMARY OF THE INVENTION
In accordance with the present invention a multi-layer conduit suitable for use as a filler conduit for hydrocarbon containing fuels includes a plurality of layers. The layers include an inner layer which is comprised of electrically conductive high density polyethylene based material. The layers also include a barrier material which acts as a barrier to reduce passage of hydrocarbons through the walls of the conduit.
In a first embodiment of the invention, the layers include an inner layer which is comprised of electrically conductive high density polyethylene based material. The conduit also includes an outer layer comprised of high density polyethylene. The conduit further includes a barrier layer of ethylene vinyl alcohol copolymer (EVOH) and two layers of adhesive, one on either side of the EVOH barrier layer for the purpose of bonding the EVOH layer to layers which are radially adjacent to the barrier layer. Advantageously, scrap regrind polyethylene based material may be used next to the conductive layer. In a particular advantageous embodiment, the first two layers comprise at least 50% of the weight per unit length of the conduit.
In another embodiment of the invention, advantageously, the conduit may be made from two layers, a radially inward layer which will be in contact with hydrocarbon fuel passing along the conduit which is electrically conductive high density polyethylene based material and a second, outward layer comprising Dupont SELAR, a blend of nylon copolymer, a proprietary adhesive for nylon and a high density polyethylene.
Advantageously, in another aspect of the invention a filler conduit, preferably incudes at least one tab for structurally attaching the conduit to a vehicle. The tab is located between the ends of the conduit and includes an electrically conductive portion for contacting a fastener. A portion of the tab is electrically conductive. This portion of the tab is electrically connected to the inner, electrically conductive layer of the conduit to assist in conducting static electricity.
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patent: 4675780 (1987-06-01), Barnes et al.
patent: 4705708 (1987-11-01), Briggs et al.
patent: 5373870 (1994-12-01), Derroire et al.
patent: 5472754 (1995-12-01), Douchet et al.
patent: 5514299 (1996-05-01), Kalwara
patent: 0 638 749 A1 (1995-02-01), None
patent: 0 730 115 A1 (1996-09-01), None
patent: 0 754 897 A1 (1997-01-01), None
patent: PCT/US90/07327 (1991-07-01), None
Sadr Changize
Shafiee Sam
Bereskin & Parr
Brinson Patrick
Salflex Polymers Ltd.
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