Fluid handling – Diverse fluid containing pressure systems – Fluid separating traps or vents
Reexamination Certificate
2002-02-26
2004-05-25
Michalsky, Gerald A. (Department: 3753)
Fluid handling
Diverse fluid containing pressure systems
Fluid separating traps or vents
C123S519000, C137S043000, C137S587000
Reexamination Certificate
active
06739350
ABSTRACT:
Current tanks for liquid or gaseous fuel need to meet a collection of safety standards because of the highly inflammable and often toxic nature of the fuel they contain. Fuel leaks through defective sealing and losses through evaporation have been the particular subject of increasingly tight regulations, particularly in applications to motor vehicles. In addition to the actual tank itself, a great many accessories associated with it may also contain fuel, for example: the conduits, various connections, pumps, filters, canisters for removing vapours, valves and safety devices, etc. These accessories often play a not insignificant part in fuel leaks of all kinds. They are sometimes even responsible for most losses of fuel from the overall system containing them together with the tank with which they are associated.
There has therefore been a search, in parallel with the reducing of the leaks caused by the tank itself, to minimize also those caused directly by each of these acessories and by the devices that interconnect them.
U.S. Pat. No. 4,852,761 discloses a tank equipped with a canister for retaining fuel vapours which is arranged inside the tank and comprises a safety valve preventing liquid from leaving the tank if the latter is inverted. This arrangement makes it possible to dispense with the conduit connecting the tank to the canister and to shorten the conduit connecting the refuelling vapour recovery device to this same canister.
According to this state of the art, the canister is not, however, associated with an OP device and the risk of evaporative losses due to the connections between this device and the canister are not insignificant.
Furthermore, the complexity of the mounting of this canister incorporated into the tank and of the independent OP device is still high. The same is true of other devices fulfilling the other function often encountered in fuel systems involving the presence of a tank (ORVR, OBD, etc.).
Furthermore, in the canister described in U.S. Pat. No. 4,852,761, the maximum fuel level permitted in the tank is relatively low, given the need not to exceed the level fixed by the position of the orifice situated at the lower end of the inclined tube internal to the canister and intended to return the liquid fuel to the tank, otherwise the separation of liquid fuel from vapours will be inhibited. Finally, a canister of this type may find itself immersed in the fuel if the tank is inclined at an exaggerated angle, when the valve which closes the tank off in the event of rolling-over has remained open because there is still a resultant force, of gravity which keeps the dense part of the valve in its lowered position. This situation may result in leaks of liquid fuel from the tank and in the composition with which the canister is filled ceasing its fuel-gas-retaining activity.
It is an object of the invention to overcome the drawbacks of the known tanks by providing a tank which cancels or very greatly limits the leaks of liquid and gaseous fuel to the external atmosphere while at the same time fulfilling the safety functions generally accomplished by modern fuel systems and very greatly simplifying the complexity of the mounting of the tank.
To this end, the invention relates to a fuel tank comprising a canister containing a composition capable of retaining fuel vapours, in which the canister is associated with an overfill prevention (OP) device preventing the tank from being overfilled and also located, at least partially, inside this tank.
A “tank” is to be understood as meaning a closed chamber, of varying shapes, generally sealed against the outside, which may be equipped with various internal accessories or accessories passing through the wall of the chamber.
The tank according to the invention may be made of any composition or material compatible with the fuels and the habitual conditions of use. It may, for example, by made of a material the composition of which contains at least one metal or one plastic. Tanks made up of at least one plastic are preferred.
A “plastic” is to be understood as meaning any synthetic polymeric material which is in the solid state under ambient conditions. Tanks made of plastic according to the invention may be in the form of single-layer or multilayer tanks. Tanks comprising one or more layers of high-density polyethylene are particularly preferred.
A “fuel” is to be understood as meaning any chemical composition capable of being burnt in the presence of an oxidizing agent, generally the oxygen in the air, which can be used in a combustion engine. Fuels may at ambient temperature be in any one of three states solid, liquid or gaseous. In vehicles, preference is generally given to fuels which are liquid or gaseous at ordinary temperature and at atmospheric pressure or higher. Liquid fuel such as petrol and diesel are particularly preferred.
An “engine” is to be understood as meaning any engine that converts the chemical energy contained in a fuel into mechanical energy. This may be any type of internal combustion engine, of the piston or rotary type, using liquid fuel (such as petrol, heavy oil, alcohol, etc.) or gaseous fuel (such as petroleum gas, natural gas, lean gas, hydrogen, methane, etc.). By extension, a “combustion engine” is also intended to cover one or more electric motors powered by at least one fuel cell when this fuel contains at least one hydrocarbon and/or an alcohol.
The canister contained in the tank according to the invention is a receptacle containing a composition, generally solid and granular, capable of retaining the fuel vapours of a gaseous stream. By way of an example of such a composition, mention may be made of granulated active charcoal. The canister may be made of any material or composition of materials compatible with the liquid and gaseous fuels with which it is intended to come into prolonged contact under the varying temperature and pressure conditions likely to be encountered inside fuel tanks. As a preference, the canister is at least partially made of plastic.
“Plastic” here has the same meaning as above. Thermoplastics and thermosets are particularly suitable. Thermoplastics have given good results.
According to the invention, the canister is contained in the tank, that is to say it is arranged completely or partially inside the latter. As a preference, it is arranged completely inside the tank.
When it is arranged completely inside the tank, the canister may be fixed to the tank by any known fixing means. Examples of possible fixing means are, non-limitingly: bottom, side or top wall in common with one wall of the tank, bottom, side or top wall welded to a wall of the tank, protrusion from a wall of the canister bolted onto a wall or an internal part secured to a wall of the tank, clipping of a wall of the canister into one or more glideways borne by or hollowed into an interior wall of the tank.
When it is arranged partially inside the tank, the canister penetrates a wall of the tank, for example the top wall. In this case, it is preferably closed in a sealed way by a cover carrying the gas inlet conduits containing the vapours that are to be purified and the clean-gas outlet conduits. In addition, it is advantageous for the cover to be made of at least one material which is practically impermeable to the fuels.
According to the invention, the canister is associated with an overfill prevention device preventing the overfilling of the tank.
An “OP device” is to be understood as meaning any device whose function is to fix the useful volume of the tank and prevent the liquid in the tank exceeding a predetermined level during the filling operation. It may be chosen from all known devices for fulfilling this function. The particular OP device with a dense ball which, by gravity, blocks off the gas outlet conduit of a capacity intended to receive liquid fuel has given good results. It is of particular benefit when the fuel vapours are discharged from the end external to the tank of the filling pipe.
The OP device according to the invention is also located, at least partially, insi
Gerard Yannick
Leonard Stéphane
Op De Beeck Joël
Perez-Perez Rufino
Van Schaftingen Jules-Joseph
Larson & Taylor PLC
Michalsky Gerald A.
Solvay ( Societe Anonyme)
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