Venting tubing system for a fuel tank

A fuel tank comprising at least one fuel vapor accessory articulately coupled with a fuel tubing extending within the fuel tank. The tubing extends from a field end of the tank towards an outlet end thereof, and is formed with at least one aperture between the field end and the outlet end. The fuel vapor accessory is disposed between the field end and the outlet end. The tubing is secured to an inside upper wall of the fuel tank.

FIELD OF THE INVENTION

This invention generally relates to venting systems for vehicle fuel tanks and more particularly it is concerned with a venting tubing system for vehicle fuel tanks.

BACKGROUND OF THE INVENTION

Vehicle fuel systems comprise, among others, a fuel tank fitted with a filler neck, a variety of fuel valves, a tubing for supplying fuel to the ignition system and a fuel vapor treating system (typically a carbon filter recovery system often referred to as a carbon canister) to which fuel vapor from the fuel tank flows and is then used for enriching the fuel mixture fed to the ignition system.

Fuel fluid (in the form of liquid, droplets, spray and vapor) from the fuel tank flows via the one or more valves which are connected, via suitable tubing, to a liquid trap intermediate the fuel vapor recovery system and the tank.

The liquid trap receives fuel fluid flowing from the fuel tank which flow at a relatively high velocity owing to pressure and temperature changes, and thus vapor flowing from the fuel tank carries along with it also a considerable amount of fuel liquid in the form of droplets. The liquid trap entraps the fuel liquid and allows fuel vapor flow towards the vapor recovery system. The fuel liquid then returns back to the fuel tank, upon pressure decrease within the fuel tank.

An important factor in attaching accessories to a fuel tank is maintaining a fuel-impermeability so as to comply with strict environmental regulations. One common practice to connect a valve to a fuel tank is by performing an aperture of a size comfortably accommodating the valve's housing, and fixedly attaching the valve by various means, e.g. welding, heat welding, different fasteners, etc. However, according to these methods, there is a need to provide special sealing means between the valve's housing and the tank.

According to another technique fuel valves are attached to the fuel tank by fusion welding the valve to the inside upper surface of the fuel tank. Alternatively, a coupler element is securely attached to the upper surface of the fuel tank and the valve is fixed to said coupler element.

The external surface of a tank holding one or more valves also carries at least a portion of an outlet nozzle and tubing connected thereto, as well as, in some cases, also some electrical wiring. This requires special space design of the fuel tank, and other considerations.

Another consideration concerned with connection of valves to tanks is the effective operation level of the valves, namely the level at which the valve closes (at times referred to as cut-off or shut-off and the level at which the valve reopens. One of the considerations governing the operative level is space consuming which is of significant importance in particular in vehicles. It is thus a requirement that the “dead space” i.e. the space between “maximum fuel level” and the top wall of the fuel tank, be reduced to minimum. However, by inserting the valve into the tank, care has to be taken not to increase the dead space.

Another parameter of concern is the time required for assembling and attaching each individual fuel vapor accessory to the fuel tank and to the articulated coupling tubing, and the costs involved therewith.

The ever-growing requirement of environment concerned organizations and authorities that the rate of fuel permeability from the fuel tank and its accessories be minimal. The outcome of this requirement is that new connection means are now required for ensuring essentially permeation-free connection between the valves and the fuel tank.

It is thus a growing trend to form as little as possible openings in the tank (ideally only one), and accordingly a venting system with its associated valves and connections are relocated as far as possible into the tank.

It is an object of the present invention to provide a concept for attaching fuel vapor accessories within a fuel tank in a substantially fuel impermeable manner. It is a further object of the invention to provide a fuel-flow coupling system interconnecting the various fuel vapor accessories. These and other objects are carried out in a substantially fuel impermeable manner, which is considered to be substantially fast and cost effective.

SUMMARY OF THE INVENTION

According to the present invention there is provided a vehicle fuel vapor system comprising tubing interconnecting various fuel vapor accessories within a fuel tank, where the tubing is continues and where the fuel vapor accessories are integral with or snappingly articulated to the tubing.

The term ‘fuel vapor accessory’ as used herein the specification and claims is used to denote any of a variety of devices/fittings commonly attached within fuel tanks (i.e. fuel system components), such as valves of different types (vent valves, roll-over valves, over filling intermitting valves, over pressure relief valves, check valves, etc), liquid traps and drains, gauges, filters, etc. and also a seating/carrier attached to the fuel tank and which in turn various valve members are attached thereto. However the invention is not limited to any particular type of fuel vapor accessory.

The term tubing as used herein the specification and claims is used to denote any tubing/tubing interconnecting between fuel vapor accessories as aforementioned.

The continuously extending tubing according to any of the embodiments of the invention, saves time and expected expenses in assembling the fuel system within the fuel tank, as compared with conventional systems where a separate tube segment extends between each fuel vapor accessory.

The invention thus calls for a fuel tank comprising at least one fuel vapor accessory articulately coupled with a fuel tubing extending from the fuel tank, said tubing secured to an inside upper wall of the fuel tank.

Any one of the following features may apply to the present invention:The at least one fuel vapor accessory may be integrated within the tubing;The at least one fuel vapor accessory may be snap-coupled to the tubing;The tubing is a continuous tube interconnecting at least two fuel vapor accessories within said fuel tank;The continuous tube envelopes the at least one fuel vapor accessory, with functional openings formed at segments corresponding with said at least one fuel vapor accessory;The tubing extends between the at least one fuel vapor accessory and a common hub member;The tubing is made of a rigid though pliable material;The tubing is pre-formed at a shape corresponding with a contour of the inside upper wall of the fuel tank, to which it is secured;The tubing is secured to the fuel tank by snap-type fasteners;Fluid flow through the tubing is facilitated through the tubing regardless the operative state of at least one fuel vapor accessory. Thus, the fuel vapor accessory occupies only a portion of the section through which it extends, leaving a free flow path;The diameter of the tubing is substantially homogeneous.The fuel vapor accessory axially extends within the tubing.

The fuel tank is typically fitted with a flange sealingly and impermeably receiving the outlet of the tubing for transfer of fuel vapor towards the canister.

The invention is further concerned with tubing and a fuel vapor accessory of the aforementioned type.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

Attention is first directed toFIGS. 1 to 3illustrating a fuel tank generally designated10comprising a venting tubing system in accordance with the present invention generally designated12. The fuel tank has a saddle or spectacle-like shape as known per se, suited for mounting within a vehicle as known in the art.

The venting tubing system12comprises a continuous tube14made of a rigid material e.g. plastic, which in accordance with an embodiment of the present invention may also be pliable or even resilient. The tubing14generally follows the shape of the fuel tank10formed with an uppermost portion18and two side lowermost portions20A and20B, interconnected by the continuous tubing, as mentioned hereinabove.

The tube14extends from a field end thereof22towards an outlet end thereof24extending into a outlet coupler26which in turn is connected via suitable tubing (not shown) to a fuel vapor treating system-canister (not shown) as known in the art.

The tubing14is integrally formed with a plurality of fuel vapor accessories generally designated30A-30F. These fuel vapor accessories may be any one or more of different valves such as vent valves, rollover valves, overfilling intermitting valves, liquid traps, liquid drains, gauges, filters, etc. However more likely, the fuel vapor accessory designated30G is a check valve (i.e. one-way flow valve) and one or both of the fuel vapor accessories designated30E and30B are liquid carry over drain valves (LCO). The fuel vapor accessories designated30D and30C are likely to be rollover valves and overfilling intermitting valves, as known in the art and for that purpose these valves are positioned at or adjacent to uppermost portions of the fuel tank10.

As can be seen in the drawings, the tubing14is substantially of equal diameter though it may be somewhat thicker at those portions of the different fuel vapor accessories. It is noticed that the fuel vapor accessories axially extend within the tubing14and whereby the tubing envelopes the respective fuel vapor accessories, however leaving necessary apertures formed therein for operation of the valves, as required. A method of manufacturing tubing in accordance with the present invention is substantially similar to that known in the art in connection with inline drip irrigation wherein the drip units (liquid emitters) are integrated into the tubing during the process of manufacturing in a continuous extrusion process.

The diameter of the tubing in accordance with the present invention may be similar to existing tubing segments used nowadays for connecting between different valve accessories or may be slightly larger, as may be required.

The tubing14may be attached to the upper wall of the fuel tank10upper ends of side Walls thereof by different fastening means, however without the need to form any apertures in the fuel tank, apart from the outlets at22. Securing the tubing14to the fuel tank may be for example by snap-type couplers generally designated38comprising a flange portion40for attaching to a respective wall portion of the fuel tank and a tube gripping portion42for snappingly arresting the tubing14. Attaching the flanged portion40to the fuel tank10may be for example by using an adhesive agent, by heat welding, fusion welding, by snap type fasteners, etc.

Turning now toFIGS. 4 and 5there is a schematic section taken along line IV-IV inFIG. 3illustrating a rollover vent valve30D integrally embedded within the tubing14. The ROV occupies a portion of the section of the tubing14, however leaving a significant free flow passage designated at46whereby fluid flow is facilitated therethrough, regardless of the position of the respective fuel valve. Accordingly, fuel flow is facilitated through the passage46regardless if the fuel vapor accessory (30B in the particular embodiment) is in its open or closed position or even in case of malfunction thereof. The rollover vent30B comprises an encapsulating body48formed with a valve inlet50and a valve outlet52, said inlet50extending above an aperture56of the tube14. A float member60is received within the body48accommodates a float member60displaceable within the space62of the valve30B, with a resilient sealing member64extending thereabove and fitted for sealing engagement with the outlet52.

In the embodiment in which the fuel vapor accessory is secured within the tubing, there is a sealing engagement therebetween so as to ensure that fuel vapor passes only through the respective accessory. Accordingly, in the example disclosed hereinabove, the body48of the valve is sealingly attached to the tubing14such that fluid flow is restricted only through the path extending through aperture56and valve inlet50.

The arrangement is such that at the inadvertent case of rollover of the vehicle or at steep traveling thereof, the float member60is displaced against the outlet52whereby the sealing member64sealingly engages the outlet52preventing fuel flow into the flow passage46. In the event of overfilling of the fuel tank the float member60is forced, by buoyancy forces, in an upward direction such that the sealing member64sealingly engages the outlet52again, preventing liquid flow into the flow passage46.

Turning now toFIG. 6there is illustrated a liquid carryover drain valve30E comprising a housing70integrated into the tubing14and extending at a lowermost portion thereof, the housing70comprises a plurality of inlet apertures72and a plurality of outlet apertures74coaxial with apertures76formed in the tubing14. Received within the housing70there is a bed78supporting a flexible diaphragm82extending below the inlet apertures72however at a normally disengaged position as illustrated inFIG. 5. The arrangement is such that at the normal course of operation liquid flow in the direction from the tubing14into the fuel tank is facilitated through apertures72, into the chamber84of the LCO drain valve and out through apertures74and76into the fuel tank. However flow in an opposite direction is not facilitated as fluid pressure within the fuel tank will cause deformation of the diaphragm82into sealing engagement of the apertures72. This is important also in case of refueling to ensure pressure build up in the fuel tank for cut-off of a refueling nozzle.

InFIG. 7there is illustrated a schematic section of a check valve30G comprising a coaxial housing88integrated within the tubing14formed with an inlet port90and an outward port92with a piston94axially displaceable therewithin and fitted at its inlet facing and with a sealing member96fitted for sealing engagement with a sealing seat98formed at the housing88. The piston94is spring biased into sealing engagement, as in the position ofFIG. 7, by means of a coiled compression spring100bearing at one end against a shoulder102of piston94and at an opposite end thereof against a packing member104fixed to the casing88. The piston94is formed with a plurality of apertures108sealing by the sealing member96in the direction from the inlet port90towards the outlet92however which apertures will open under pressure in the event of pressurizing in the direction of outlet port92to thereby deform the sealing member96to facilitate flow through apertures108towards the inlet port90. However, the apertures108remain sealed in flow in the direction from inlet port90towards outlet port92whereby flow in this direction is facilitated only upon pressure increase overcoming the biasing affect of the coiled spring100, to facilitate fluid flow at substantially high flow rates.

Turning now to the embodiment ofFIGS. 8 to 10there is illustrated a fuel tank110, similar to fuel tank10of the previous embodiment, however fitted with a venting tubing system in accordance with the somewhat different embodiment generally designated120.

The tubing system120comprises a continuously extending venting tube124fitted within the space of the fuel tank110in a similar manner as disclosed in connection with the previous embodiment, however with only one outlet formed in the fuel tank, at116, in a manner which ensures fuel impermeability.

Whilst in the previous embodiments, the fuel vapor accessories were enveloped by the tubing14, in accordance with the present embodiment, the fuel vapor accessories130A through130F are external to the tubing124and are fixedly secured to the tubing, e.g. in a snap-type connection as illustrated inFIG. 11. This arrangement is suitable for fast and efficient coupling of different fuel vapor accessories, as discussed hereinabove, in a snap-type manner to be distributed within the fuel tank at desired locations.

The rollover vent valve130E illustrated inFIG. 11comprises a snap shank portion140formed with a shoulder142such that when it is snapped into an aperture formed into the tubing124it is sealingly arrested thereby preventing its retraction and firmly positioning it. The ROV130E comprises a housing144formed with an outlet146, one or more inlets148, a float member150supporting a sealing member152fitted for sealing engagement with a sealing shoulder154of the outlet146.

The float member150is displaceable between an open position, as inFIG. 11, wherein the valve130E facilitates venting of the fuel tank through inlet ports148, via space156and through outlet146into the flow passage158of the tubing124. However, upon filling the fuel tank, liquid level within the tank causes the float member150to displace upwardly such that the sealing member152engages the sealing shoulder154to shut the outlet146. Similarly, in case of turnover of the vehicle, the float member150displaces such that the sealing member152sealingly engages the outlet shoulder154preventing fuel flow through the outlet146into the flow passage158.

Whilst some particular embodiments have been described and illustrated with reference to some drawings, the artisan will appreciate that many variations are possible which do not depart from the general scope of the invention, mutatis, mutandis. This refers, for example, to the different fuel vapor accessories which may be used and the modifications of the tubing, however with a continues tube as discussed.