Fuel system for a vehicle

Internal-combustion engines – Charge forming device – Fuel flow regulation between the pump and the charge-forming...

Reexamination Certificate

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C123S518000, C123S519000, C137S587000

Reexamination Certificate

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06634342

ABSTRACT:

The present invention relates to a fuel system for a vehicle.
In vehicles with a heat engine, in particular in motor vehicles, the tanks currently used for retaining liquid or gaseous fuel often consist mainly of plastic, because of the advantages of weight, mechanical strength, chemical stability and ease of use, in particular when they have complex external shapes, A large number of accessories for these tanks forming part, like the latter, of the components providing the fuel function of vehicles are also, increasingly, made entirely or partly of plastic. These accessories include, among other things, the fuel feed pipes, the vent valves, the canisters with activated carbon for absorbing vapours, the fuel filters and pumps and the filler nozzles.
The recent increase in the strictness of standards in respect of the environment, in particular those relating to hydrocarbon emissions by vehicles with a heat engine, has made it necessary to further improve the impermeability of on-board tanks, and also of Their accessories and connections. This is because it is not unusual for the overall evaporative losses of all of the latter to be of the same order of magnitude as, or even in some cases to exceed, those which are strictly due to the tank itself. The prospect of drastic strengthening, scheduled for the short term, of the restrictive nature of these environmental standards leads to the imperative need to develop orginal overall solutions, the impermeability and sewn, performances of which far exceed the values currently required at present
Various techniques are known to make the surfaces of objects made of plastic impermeable. Two different approaches have led to proposing solutions which have been implemented in the methods for manufacturing these objects. The first is based on the surface treatment of the object by means of a plasma or of a chemical reagent such as sulphuric anhydride or fluorine gas capable of altering the molecules of the plastic located at the surface of the object Another approach consists in inserting, within the thickness of the plastic forming the object, a layer consisting of a particular material, often a thermoplastic, with a barrier property with respect to one or several gases or liquids. In the latter case, broad use has been made of implementary techniques using co-extrusion.
Patent Application JP-A-08/118971 describes a fuel tank, the lower part of which has a two-layer structure separated by an empty space. Two orifices drilled in the outer layer allow ambient air to enter over the face of the tank located at the front end of the vehicle. When the vehicle is moving, the air enters the orifices, flows between the two layers and exits by means of two other orifices drilled in its outer layer, in Me direction of the rear of the vehicle. The flow of air between the two layers when the vehicle is moving cools the tank and its contents and keeps it at a moderate temperature, which has the effect of reducing the generation of hydrocarbon vapours by the tank
However, the hydrocarbon losses by evaporation are not eliminated by this fuel tank configuration, This is because the air discharged to the atmosphere which leaves the double layer is loaded with an amount of vapour which corresponds to the evaporative losses of the tank.
Moreover, no cooling occurs when the vehicle is stationary and the generation of vapours is then at a maximum.
French Patent Application FR-2697892-A1 discloses a triple pipe with four concentric walls in which the inner pipe and the intermediate pipe transport fuel from a tank towards an engine and back. In the outermost pipe, gases are withdrawn from the tank and are injected into the pipe which transports them to a treatment device.
In this document, no mention is made of any flushing of vapours which would pass through the inner walls.
German Patent Application DE-4142016-A1, which constitutes the closest prior art, relates to a system in which a fuel tank is surrounded by a second skin, thereby defining a space which is filled with material absorbing the fuel vapours. However, in this system, no mention is made of a partial jacket around the tank made by a wall of the vehicle.
To this end, the invention relates to a fuel system for a vehicle with a heat engine, comprising a hollow body made of metal or of plastic, designed to contain or to transport fuel, and means of covering this hollow body, in which at least part of the outer surface of the hollow body is surrounded by a rigid jacket, the hollow body and the rigid jacket defining, at least in part, at least one confined space around the hollow body, and according to which the confined space is fitted with a device for flushing by means of a gas intended to be subjected subsequently to a physical or chemical treatment, this confined space being defined, at least in part, by the jacket and by a wall of the vehicle.
The term “fuel” denotes any chemical composition which can be burnt in the presence of an oxidant, generally the oxygen in air, which can be used in a heat engine equipping a vehicle. The fuels may be at ambient temperature in any of the three, solid, liquid or gaseous, states. In vehicles, fuels which are liquid or gaseous at room temperature and under atmospheric pressure or greater are generally preferred. Liquid fuels such as petrol and diesel are most particularly preferred.
The fuel system according to the invention is intended for any vehicle with a heat engine, in particular for motor vehicles such as tracks, cars and motor cycles. The term “heat engine” is intended to designate any engine converting the chemical energy contained in a fuel into mechanical energy. It may consist of any type of internal combustion engine, piston-type engines or rotary engines, using liquid fuels (such as, for example, petrol, fuel oil, alcohol, etc.) or gaseous fuels (such as, for example, petroleum gas, natural gas, lean gas, hydrogen, methane, etc.).
By extension, the term “heat engine” is also intended to designate one or more electrical engines supplied by at least one fuel cell in the case where this fuel comprises at least a hydrocarbon and/or an alcohol,
The fuel system designates any device incorporated in the vehicle, the function of which is to store, purify, measure or transport a fuel intended to supply the heat engine. The fuel system comprises at least one tank and a pipe supplying the motor with fuel. It may also comprise, in a non-limiting manner, one or more of the following accessories: pipe and valve for venting the tank, filler nozzle, canister comprising a material which retains the hydrocarbon vapours, fuel filter, fuel pump, tank gauge, electrical connector, closure cap and any member, in general, through which the fuel passes in the liquid or gaseous state.
The term “hollow body” denotes any object whose surface has at least an empty or concave part
The hollow body of the fuel system according to the invention is made of metal or of plastic. In the latter case, it comprises at least one synthetic polymer which is in the solid state under ambient conditions. Hollow bodies made of plastic are preferred, because of Their better elasticity and their greater ability to be formed into complex shapes. The term “plastic” denotes both the generally homogeneous material of a monolayer structure and the heterogeneous material of a multilayer structure. In particular, the hollow body advantageously comprises at least one thermoplastic polymer, that is to say, a polymer which, under the influence of heat, melts or softens enough to enable it to be shaped.
The term “means of covering” the hollow body denotes any device or system associated with the hollow body and providing, or at least improving, the insulation of the hollow body from the atmosphere external to the vehicle and/or stresses of a physical or chemical nature which arise from this external atmosphere. By way of example, mention may be made, among others, of thermal insulation devices, acoustic insulation devices, shields, cladding and jackets of various types and shells for mechanical protection
A

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