700025554

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FrELD OF INVENTION
[0001] The present invention relates to an apparatus for tapping fuel vapors from a fuel tank and more particularly to an apparatus for tapping fuel vapors, which is integrated with a roll over valve.
5 BACKGROUND OF INVENTION
[0002] In an evaporative emission control (EVAP) system, the fuel vapour
generated in the fuel tank is tapped and passed to the carbon canister through a
discharge tube. The vapors get,..ads_o_rbed ,on..the surface of carbon granules packed
inside the canister.. The adsorbed vapors are in turn sent to the throttle body of the
10 induction system by purging action. A vapour tapper is installed preferably in the upper
region of the fuel tank to tap vapours generated due to evaporation of volatile fuel. A separate part called roll-over valve is required mostly outside the fuel tank to restrict the liquid fuel entry in to the canister in case of vehicle falling on the ground or due to' banking or road gradients.
15 [0003] The arrangement of these parts namely, a vapor tapper, a roll over valve, and
a hose routing to the canister, occupies ample space, requires more numbers of parts like hoses, guides and mounting brackets. A probable solution to the above problem is to install the vapour tapper mechanism installed inside the tank, which will reduce the capacity of the fuel tank of the vehicle. In addition, such a system apart from reduction
20 in fuel tank capacity, will-lead to difficult packaging and layout clearance of EVAP
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parts, increased EVAP system cost, more number of holes in the fuel tank, manufacturing difficulties and liquid-vapour separation difficulty.
SUMMARY OF THE INVENTION
[0004] Hence, to obviate the problems associated with the above systems for
5 tapping vapors in an EVAP system, a new vapor tapping mechanism is proposed
wherein the vapor tapper is integrated with the roll over valve and this integrated system of tapping vapours and roll over valve is situated on top of the fuel tank. The vapour tapper unit as disclosed in the current invention is performing several important functions with various advantages.
10 [0005] First, venting of tapped air or vapour when fuel is filled to its maximum
capacity; second, tapping of vapours and channeling the same to the canister. Thirdly, the current invention restricts passage of liquid fuel due to fuel slosh in vehicle running condition and allows only vapours to pass to canister. Fourthly, the current system restricts fuel entry to the canister during vehicle roll-over, leaning, tipping, banking or
15 on road gradient, thereby, performing the function of roll-over, valve and lastly the
present system establishes and maintains minimum volume for fuel expansion in fuel tank, thereby avoiding pressure build-up, which if not done can lead to rise in fuel level towards inlet and may result in fuel leakage.
[0006] By implementing the vapour tapping system as disclosed in the current
20 invention, the rollover valve is eliminated; hence, reduction in number of parts like
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hoses, guides, brackets and boots is achieved. This reduction in number of parts further
reduces the cost and layout packaging problem. The vapour tapper arrangement as
disclosed in the current invention is not inside the fuel tank; hence, fuel tank capacity is
not reduced. Also, installing a vapour tapper inside a plastic tank has got manufacturing
5 constraints and hence it is difficult to manufacture, the problem is solved by the current
proposed invention. The current invention being for vapour tapper housing using a separate housing for. vapour tapping, no major changes are required in the fuel tank design.
BRIEF QESCRIPTION OF DRAWINGS
10 Figure lillustrates a typical fuel tank of a two-wheeler.
Figure 2illustratesa the sectional view of a typical two-wheeler fuel tank.
Figure 3 illustrates the integrated vapor tapper and roll over mechanism proposed in the current invention.
Figure 4 illustrates the process flow of vapor tapping from the fuel tank to the canister.
15 DETAILED DESCRIPTION OF THE INVENTION
[0007] An evaporated fuel contained in the fuel tank is absorbed by a canister which is connected to the fuel tank through a hose. A fuel vapour tapping arrangement is made on top of the tank using the EW (extra vapour vent) projection on the upper surface of the tank. A vapour tapping housing is placed over EVV portion in such a
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way that there is a space created between the EVV and the vapour tapping housing to
collect vapours and a nipple is also provided to channelize fuel vapour to the canister.
The vapour tapping housing is equipped with a steel ball, which is used to close a
tapered opening and restrict fuel going out of the fuel tank during vehicle roll over /
5 banking /falling/ ride through gradients. Two holes are provided in the bottom region of
the vapour tapper housing arrangement to ensure the drainage of liquid fuel which might enter the vapour tapping housing due to slosh or vehicle jerks, hence, separating the fuel vapours from liquid fuel.
[0008] The vapour tapping housing is coupled to the extra vapor vent projection to ,.
10 ensure proper positioning and tightness of the joint so that no vapour leaks from this
coupling. A vapour outlet is provided on the periphery of vapour tapping housing which is connected to a hose which will guide the vapours from vapour tapper housing to the external canister. The canister is connected to the air-fuel metering system through the purge hose.
15 [0009] Figure 1 shows a typical fuel tank 1. Figure 1 shows a fuel tank cap inlet 2,
fuel tank inner 3, an extra vapour vent 4, fuel tank outer body 5 and fuel tank outlet 6 which delivers fuel to the carburetor of the vehicle. The fuel level is shown by a datum line 7. The volume below the datum line 7 is filled with fuel and the volume above the datum line 7 is empty but filled with fuel vapour and air. During normal running
20 condition of the vehicle, when fuel level goes down, it is required that the fuel tank 1
breathes some air in so as not to create vacuum for which the extra vapour vent 4 is
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used. Also, there shall be no pressure build up inside the fuel tank 1, hence, the fuel tank 1 must vent out the extra vapour to the outer atmosphere to release the pressure and avoid pressure building inside the fuel tank.
[00010] Figure 2 shows the section view of the fuel tank 1 shown in Figure 1. The fuel tank inlet 2, fuel tank inner 3, vapour tapper housing 4 is shown. The Figure shows inner construction of the vapour tapping housing 4 which is more explained in Figure 3.
[00011] Figure 3 illustrates the vapour tapping housing and its mechanism dealt in with more detail. Figure 3 shows the fuel tank inner 3, vapour tapping housing 4, fuel tank top surface 5, vapour tapping housing top surface 31, vapour tapper housing top empty space 32, roll over ball 10, conical roll over profile 33, vapour tapper housing outlet 34, vapour tapping housing length 35 and vapour travelling path 36. The vapour stored in the fuel tank inner 3 top portion travels inside the vapour tapping housing 4 through the vapour tapping housing length 35 passing through the gap between the roll over ball 10, travelling through the vapour tapper housing top empty space 32 and finally exits through the vapour tapper housing outlet 34.
[00012] The roll over ball 10 functions as to inhibit the flow of fuel in the liquid form from the fuel tank inner 3 side to the vapour tapper housing outlet 34. For this to take place, whenever the vehicle falls or topples or bends on curves, the roll over ball 10 is lifted upwards and blocks the fuel passage flow by seating on the conical roll over profile 33. In normal vehicle running condition, the roll over ball 10 sits at the bottom portion of the vapour tapping housing length 35 and allows vapours to travel towards
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the vapour tapper housing outlet 34 following the vapour travelling path 36. The vapour
tapper housing top surface has a press fit profile 37A, 37B which covers the said
vapour tapper housing top surface's periphery to provide ample sealing effect so as no
vapour is allowed to leak through the gap between the fuel tank top surfaces 5 and
5 vapour tapping housing length 35.
[00013] Figure 4 illustrates the mechanism of tapping the fuel vapours and its
application to provide the fuel vapours to the canister. The fuel vapours tapped into the
vapour'tapping mechanism 4 is sent to the evaporative emission canister 42 through
fuel vapour hose 41. The fuel vapours from the .evaporative, emission, canister 42 are
10 then fed further to the engine. Thus this way the vapours are controlled not to be vented
out into the atmosphere but are used as fuel into the internal combustion engine.
[00014] The proposed invention for tapping fuel vapours is applicable to two
wheelers both scooter and motorcycle and also to.three wheelers. In all the applications,
the proposed vapour tapping mechanism 4 is preferably placed on top surface of the
15 fuel tank and outside the fuel tank. The vapour tapping housing as disclosed in the
current invention is simple in construction and reduces number of parts and hoses for routing the vapour lines.


700025553

We claim:
1. A system for vapour trapping (4) comprising:
a fuel tank (1) wherein the said fuel tank (1) stores fuel and fuel vapours;
an extra vapour vent (4) with a converging profile (33) to vent the vapours
5 formed and accumulated in the said fuel tank (1) top portion;
a vapour trapping housing (31) with a vapour vent (4);
a roll over mechanism comprising of a ball (10) which sits at bottom portion
of the converging profile (33) to allow the vapours to vent out in normal
vehicle condition and block passage of fuel through the said converging
10 profile (33) in vehicle roll over case;
wherein the said extra vapour vent (4) is integrated with and is enveloped by the said vapour trapping housing (31) and the roll over mechanism along with the said vapour trapping housing (31) being placed on top portion of the said fuel tank (1).
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2. The roll over mechanism as claimed in Claim 1 has atleast one hole (38) on lower
• portion to allow fuel to fall back into fuel tank (1) during jerking or sudden break.
3. The vapour trapping housing (31) as Claimed in Claim 1 is preferably made of an
20 elastic material.

?amiah Member-R&D
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