Abstract:
A fuel tank comprising at least one fuel vapor accessory articulately coupled with a fuel tubing extending from the fuel tank. The tubing is secured to an inside upper wall of the fuel tank.

Description:
FIELD OF THE INVENTION 
       [0001]    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 
       [0002]    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. 
         [0003]    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. 
         [0004]    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. 
         [0005]    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&#39;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&#39;s housing and the tank. 
         [0006]    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. 
         [0007]    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. 
         [0008]    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. 
         [0009]    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. 
         [0010]    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. 
         [0011]    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. 
         [0012]    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 
       [0013]    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. 
         [0014]    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. 
         [0015]    The term tubing as used herein the specification and claims is used to denote any tubing/tubing interconnecting between fuel vapor accessories as aforementioned. 
         [0016]    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. 
         [0017]    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. 
         [0018]    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.       
 
         [0030]    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. 
         [0031]    The invention is further concerned with tubing and a fuel vapor accessory of the aforementioned type. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0032]    In order to understand the invention and to see how it may be carried out in practice, some embodiments will now be described, by way of non-limiting examples only, with reference to the accompanying drawings, in which: 
           [0033]      FIG. 1  is an isometric view of a fuel tank fitted with a fuel piping system in accordance with a first embodiment, the fuel tank being transparent for visualizing the tubing system; 
           [0034]      FIG. 2  is a rear view of the fuel tank of  FIG. 1 ; 
           [0035]      FIG. 3  is a bottom view of the fuel tank of  FIG. 1 ; 
           [0036]      FIG. 4  is schematic section of a roll over valve of the first embodiment taken along line IV-IV in  FIG. 3 ; 
           [0037]      FIG. 5  is an enlargement of a section of an ROV valve marked V in  FIG. 3 ; 
           [0038]      FIG. 6  is an enlargement of a drain valve of the tubing segment marked VI in  FIG. 3 ; 
           [0039]      FIG. 7  is an enlargement of the segment marked IV in  FIG. 3 , illustrating a check valve integrated into the tubing system; 
           [0040]      FIG. 8  is an isometric view of a fuel tank fitted with a venting tubing system in accordance with another embodiment of the invention, the fuel tank being made transparent for visualizing the venting system; 
           [0041]      FIG. 9  is a rear view of the fuel tank seen in  FIG. 8 ; 
           [0042]      FIG. 10  is a bottom view of the fuel tank seen in  FIG. 8 ; and 
           [0043]      FIG. 11  is a section along line XI-XI in  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0044]    Attention is first directed to  FIGS. 1 to 3  illustrating a fuel tank generally designated  10  comprising a venting tubing system in accordance with the present invention generally designated  12 . 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. 
         [0045]    The venting tubing system  12  comprises a continuous tube  14  made 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 tubing  14  generally follows the shape of the fuel tank  10  formed with an uppermost portion  18  and two side lowermost portions  20 A and  20 B, interconnected by the continuous tubing, as mentioned hereinabove. 
         [0046]    The tube  14  extends from a field end thereof  22  towards an outlet end thereof  24  extending into a outlet coupler  26  which in turn is connected via suitable tubing (not shown) to a fuel vapor treating system-canister (not shown) as known in the art. 
         [0047]    The tubing  14  is integrally formed with a plurality of fuel vapor accessories generally designated  30 A- 30 F. 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 designated  30 G is a check valve (i.e. one-way flow valve) and one or both of the fuel vapor accessories designated  30 E and  30 B are liquid carry over drain valves (LCO). The fuel vapor accessories designated  30 D and  30 C 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 tank  10 . 
         [0048]    As can be seen in the drawings, the tubing  14  is 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 tubing  14  and 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. 
         [0049]    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. 
         [0050]    The tubing  14  may be attached to the upper wall of the fuel tank  10  upper 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 at  22 . Securing the tubing  14  to the fuel tank may be for example by snap-type couplers generally designated  38  comprising a flange portion  40  for attaching to a respective wall portion of the fuel tank and a tube gripping portion  42  for snappingly arresting. the tubing  14 . Attaching the flanged portion  40  to the fuel tank  10  may be for example by using an adhesive agent, by heat welding, fusion welding, by snap type fasteners, etc. 
         [0051]    Turning now to  FIGS. 4 and 5  there is a schematic section taken along line IV-IV in  FIG. 3  illustrating a rollover vent valve  30 D integrally embedded within the tubing  14 . The ROV occupies a portion of the, section of the tubing  14 , however leaving a significant free flow passage designated at  46  whereby fluid flow is facilitated therethrough, regardless of the position of the respective fuel valve. Accordingly, fuel flow is facilitated through the passage  46  regardless if the fuel vapor accessory ( 30 B in the particular embodiment) is in its open or closed position or even in case of malfunction thereof. The rollover vent  30 B comprises an encapsulating body  48  formed with a valve inlet  50  and a valve outlet  52 , said inlet  50  extending above an aperture  56  of the tube  14 . A float member  60  is received within the body  48  accommodates a float member  60  displaceable within the space  62  of the valve  30 B, with a resilient sealing member  64  extending thereabove and fitted for sealing engagement with the outlet  52 . 
         [0052]    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 body  48  of the valve is sealingly attached to the tubing  14  such that fluid flow is restricted only through the path extending through aperture  56  and valve inlet  50 . 
         [0053]    The arrangement is such that at the inadvertent case of rollover of the vehicle or at steep traveling thereof, the float member  60  is displaced against the outlet  52  whereby the sealing member  64  sealingly engages the outlet  52  preventing fuel flow into the flow passage  46 . In the event of overfilling of the fuel tank the float member  60  is forced, by buoyancy forces, in an upward direction such that the sealing member  64  sealingly engages the outlet  52  again, preventing liquid flow into the flow passage  46 . 
         [0054]    Turning now to  FIG. 6  there is illustrated a liquid carryover drain valve  30 E comprising a housing  70  integrated into the tubing  14  and extending at a lowermost portion thereof, the housing  70  comprises a plurality of inlet apertures  72  and a plurality of outlet apertures  74  coaxial with apertures  76  formed in the tubing  14 . Received within the housing  70  there is a bed  78  supporting a flexible diaphragm  82  extending below the inlet apertures  72  however at a normally disengaged position as illustrated in  FIG. 5 . The arrangement is such that at the normal course of operation liquid flow in the direction from the tubing  14  into the fuel tank is facilitated through apertures  72 , into the chamber  84  of the LCO drain valve and out through apertures  74  and  76  into the fuel tank. However flow in an opposite direction is not facilitated as fluid pressure within the fuel tank will cause deformation of the membrane  82  into sealing engagement of the apertures  72 . This is important also in case of refueling to ensure pressure build up in the fuel tank for cut-off of a refueling nozzle. 
         [0055]    In  FIG. 7  there is illustrated a schematic section of a check valve  30 G comprising a coaxial housing  82  integrated within the tubing  14  formed with an inlet port  90  and an outward port  92  with a piston  94  axially displaceable therewithin and fitted at its inlet facing and with a sealing member  96  fitted for sealing engagement with a sealing seat  98  formed at the housing  88 . The piston  94  is spring biased into sealing engagement, as in the position of  FIG. 7 , by means of a coiled compression spring  100  bearing at one end against a shoulder  102  of piston  94  and at an opposite end thereof against a packing member  104  fixed to the casing  88 . The piston  94  is formed with a plurality of apertures  108  sealing by the sealing member  96  in the direction from the inlet port  90  towards the outlet  92  however which apertures will open under pressure in the event of pressurizing in the direction of outlet port  92  to thereby deform the sealing member  96  to facilitate flow through apertures  108  towards the inlet port  90 . However, the apertures  108  remain sealed in flow in the direction from inlet port  90  towards outlet port  92  whereby flow in this direction is facilitated only upon pressure increase overcoming the biasing affect of the coiled spring  100 , to facilitate fluid flow at substantially high flow rates. 
         [0056]    Turning now to the embodiment of  FIGS. 8 to 10  there is illustrated a fuel tank  110 , similar to fuel tank  10  of the previous embodiment, however fitted with a venting tubing system in accordance with the somewhat different embodiment generally designated  120 . 
         [0057]    The tubing system  120  comprises a continuously extending venting tube  124  fitted within the space of the fuel tank  110  in a similar manner as disclosed in connection with the previous embodiment, however with only one outlet formed in the fuel tank, at  116 , in a manner which ensures fuel impermeability. 
         [0058]    Whilst in the previous embodiments, the fuel vapor accessories were enveloped by the tubing  14 , in accordance with the present embodiment, the fuel vapor accessories  130 A through  130 F are external to the tubing  124  and are fixedly secured to the tubing, e.g. in a snap-type connection as illustrated in  FIG. 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. 
         [0059]    The rollover vent valve  130 E illustrated in  FIG. 11  comprises a snap shank portion  140  formed with a shoulder  142  such that when it is snapped into an aperture formed into the tubing  124  it is sealingly arrested thereby preventing its retraction and firmly positioning it. The ROV  130 E comprises a housing  144  formed with an outlet  146 , one or more inlets  148 , a float member  150  supporting a sealing member  152  fitted for sealing engagement with a sealing shoulder  154  of the outlet  146 . 
         [0060]    The float member  150  is displaceable between an open position, as in  FIG. 11 , wherein the valve  130 E facilitates venting of the fuel tank through inlet ports  148 , via space  156  and through outlet  146  into the flow passage  158  of the tubing  124 . However, upon filling the fuel tank, liquid level within the tank causes the float member  150  to displace upwardly such that the sealing member  152  engages the sealing shoulder  154  to shut the outlet  146 . Similarly, in case of turnover of the vehicle, the float member  150  displaces such that the sealing member  152  sealingly engages the outlet shoulder  154  preventing fuel flow through the outlet  146  into the flow passage  158 . 
         [0061]    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.