FIELD OF INVENTION

[0001] The present invention relates to a vapour tapping mechanism and more particularly to a vapour tapping mechanism integrated with a roll over protection in a fuel tank of a two-wheeler.

BACKGROUND OF INVENTION

[0002] In an evaporative emission control (EVAP) system, the fuel vapour generated in the fuel tank is tapped and directed to the carbon vapour canister through a discharge tube. The vapours are adsorbed onto the activated carbonjnsi.de the canister.

[0003] The performance of the carbon vapour canister gets significantly affected if liquid fuel enters the canister. To prevent this phenomenon, a very common practice is to use a rollover valve (ROV) which blocks the liquid fuel entry to the canister when the vehicle falls, banks or negotiates a steep gradient.

[0004] Normally the rollover valve is installed externally in the EVAP system. This arrangement occupies ample amount of space for mounting the rollover valve and for pipe routing and its guiding brackets. A rollover valve integrated with the tank cap that also has a provision for replacing ROV without replacement of the entire cap in case of any failure is also well known. In other known arrangements normally an external pipe for carrying the vapors from the fuel tank is connected to roll over valve and then to the canister. Hence, number of parts and time required for assembly/disassembly is increased. Hence a simple cost effective design solution for replacing the rollover valve and its associated parts are proposed which will need lesser number of parts and will take lesser time for assembly.

SUMMARY OF THE INVENTION

[0005] The invention discloses the usage of two (or more) identical polymer inserts instead of a separate rollover valve and its associated pipe connections, mounting brackets and guiding brackets and thereby enhancing the cost effectiveness & reduction in part count of EVAP system. Due to elimination of ROV & associated parts & connections, vehicle layout becomes simpler. This is a significant advantage, in case of two wheeler as vehicle layout is normally densely packed.
[0006] This design reduces the number of pipe connections which are potential vapour leak paths in the EVAP system, and hence serves as prevention design control for leakage in the system. Such a mechanism doesn't use any external pipe for carrying the vapors from the fuel tank to roll over valve and then to the canister since the roll over valve is eliminated. Hence, number of parts and time required for assembly is decreased. In the proposed invention a simple low cost alternative design solution for replacing the rollover valve and its associated parts are described which will need lesser number of parts and will take lesser time for assembly.

BRIEF DESCRIPTION OF DRAWINGS

Figure lillustrates a typical two-wheeler.

Figure illustrates a typical fuel tank of a two-wheeler.

Figure 3 illustrates the vapour,tapping housing in the fuel tank.

Figure 4 illustrates the location and float arrangement in the vapour tapping housing.

Figure 5 illustrates the fins of the float.

Figure 6 illustrates the float insertion in vapour tapping housing of the fuel tank.

Figure 7 illustrates the inserted float in the vapour tapping housing in the fuel tank.

• Figure 8 illustrates the float mechanism inside vapour tapping housing in the fuel tank during normal ride.

Figure 8 illustrates the float mechanism inside vapour tapping housing in the fuel tank during banking.

DETAILED DESCRIPTION OF THE INVENTION

[0007] A typical fuel tank.of a two wheeled vehicle comprises of a fuel tank outer body sandwiched with a fuel tank inner body so as the space in between the fuel tank outer body and fuel tank contains the fuel. Fuel tank outer and fuel tank-inner are welded together and a fuel inlet/neck is joined (welded) to the said fuel tank outer for filling fuel inside the fuel tank. A fuel vapour discharge pipe which runs from top inside of the said fuel tank to the outside of the fuel tank through a hole in the fuel tank. inner and is connected to a canister containing activated carbon for adsorbing fuel . vapour.

[0008] A vapour tapping enclosure/chamber covers the top of the vapour'discharge tube and it has an opening through which the vapour discharge tube is inserted in such a way that at-least a portion of the vapour discharge tube is inside the said enclosure, leaving a small air-gap. The vapour tapping enclosure/chamber has flat base and the base having one or more openings/holes towards the vertically downward direction for communication between the fuel tank and the chamber. In such a vapour tapping chamber, a set of polymer inserts/floats is pressed inside each of the breather holes. The design of float / polymer inserts is finalized, such that they freely float during vehicle tilt.

[0009] The insert has a set of arms (in this case four) in the top and which extends to a tapered stem and a conical bottom supported by a flat base. The arms flex during insertion of the float into the breather hole. After insertion the" arms rest on the inside flat surface of the chamber. The communication between tank and the chamber is provided through the annular opening created there-of between the stem of the float and the breather hole.

[00010] If vehicle is upright on flat road without any gradient, the inserts hang down with their arms resting at the flat face of the vapour tapper. The fuel vapours generated in the fuel tank enters the vapour separation chamber via the annular opening between the stem of the float insert and the breather holes in the vapour separation chamber.

[00011] When the vehicle tilts beyond a pre-determined angle or rolls over, the fuel inside the fuel tank approaches the upper surface of the tank and in such a case, the inserts act as a float. The lifting of float closes the path between the fuel tank and the vapour tapping enclosure due to float's periphery which is in shape of the cone. The floats remain vertical during normal conditions and vapours are allowed to the vapour tapper'enclosure from the fuel tank. In case of vehicle rollover or tilt beyond a predetermined angle, the fuel level in the fuel tank approaches the breather hole. When the fuel level touches the insert, the insert act as float and lifts up due to buoyancy to close the annular opening by the periphery of the conical bottom provided in the float.

[00012] Thereby, the liquid fuel entry is prevented from entering the chamber and hence to the. canister. This f phenomenon occurs whenever the fuel level comes in.,, contact with the float inserts. Thus the arrangement prevents the liquid fuel entry not only during vehicle banking and rollover but also in the other undesirable conditions like vehicle inclination in gradient i.e., tilt w.r.t vehicle transverse (pitch axis) and overfilling of fuel beyond declared max capacity. Thus, the disclosed design arrangement prevents the liquid fuel entry into the vapour tapping chamber in all circumstances and thereby serves as a better alternate design for rollover valve in the EVAP system.

[00013] As shown in Figure 1, a two wheeled vehicle 10 is shown. The two wheeled vehicle 10 has a rider seat 1, fuel tank 2, canister 3, main pipe 4, head pipe 5, front shock absorber 6, front wheel 7, engine 8 and a rear wheel 9.The fuel is stored inside, the fuel tank 2. The vapours from the fuel tank 2 reach the canister 3. through a vapour transmission system involving pipes and roll over valve. It is necessity of the system that the .liquid fuel shall not pass into the canister.

[00014] As shown in Figure 2, figure 2 shows the fuel tank 2, fuel tank outer 21, vapour trapper 22, vapour pipe 33, fuel tank inner 24 and fuel tank inside 25. The fuel is stored between the fuel tank inner 24 and the fuel tank outer 21. The volume 25 is created by the space in-between the fuel tank inner 24 and the fuel tank outer 21 which is the volume where fuel resides. The vapour trapper 22 is situated at the topmost portion' of the volume 25. A pipe is attached to the vapor tapping mechanism 22 to tap r.. the. vapor from..the fuel tank and bring it out of the fuel tank for transmitting to_.the.„„ canister.

[00015] As shown in Figure 3, figure 3 shows the vapour trapper 22, vapour inlet to vapour tapper chamber 31, vapour chamber 32, vapour pipe 33, and float 34, vapour tapper lower surface 35.Under normal vehicle running conditions, the floats 34 sit on the lower surface 35 of the vapour tapper mechanism 22 in such a way that a small gap is there in-between the float 34 and the surface 35 through which vapours can easily pass to the vapor tapper mechanism 22 from the fuel tank which has been described in a more detail in Figure 4. The vapours from the fuel tank enters the vapor tapper chamber 22 through gap 31 and the vapours further travel to the vapour-pipe 33 which is connected to the canister. Thus the cycle of vapour tapping and vapor flow to the canister from the fuel tank gets completed.

[00016] As shown in Figure 4, figure 4 shows the vapour trapper 22, vapour chamber 32, vapour travel direction 41, float stem 42, surface vapour chamber 43, vapour pipe 33 and float fins 44.The mechanism of passing off of vapor from the vapor chamber 32 to the vapour pipe 33 is in detail explained in the magnified view of portion containing float 34. The float 34 sits on lower surface 43 of vapour chamber 32 aiid comprises of atleast two fins 44 wherein the two adjacent fins 44 are separated with gap through which the vapours can vent from vapour chamber 32and travel to the canister through the vapour pipe 33.

- [00017] As shown in Figure 5 the float used in Figure 4 has be&n-illustrated-in-.more detail. Figure 5 shows a float stem 42, floats fins 44, fin gaps 51 and float base 52. The end tip of the float fins 44 sits on the lower surface 43 of the vapour housing 32. The vapour from the fuel tank top travels to the vapour housing 32 through the gap between two adjacent fins namely the float fin 44. It must be observed that the stem 42 of the float is conical in shape with higher diameter near base and lesser diameter near top.

[00018] As shown in Figure 6, figure 6 shows the sectional view of vapour trapper 22, vapour tapper housing 32, vapour pipe 33, first float gap 61, second float gap 62, first float 63 and a second float 64.The floats 63 and 64 are to be inserted in the float gaps 61 and 62.

[00019] As shown in Figure 7, figure 7 illustrates the floats inserted into the lower surface of the vapour housing 32. Figure 7 vapour trapper 22, vapour tapper housing 32, vapour pipe 33, second float gap 62 and first float 63.

[00020] As shown in Figure 8, figure 8 shows the fuel tank 2 in normal vehicle running condition. Under normal vehicle running condition, the fuel tank remains vertical and does so the floats due to which the passage between the fuel tank top and the vapour housing 32 is maintained. Figure 8 shows vapour trapper 22, fuel tank inner 24, fuel tank inside 25, fuel tank inside top 81, vapour flow path 82 and vapour flow to canister 83. As seen in the magnified view of the vapour trapper 22, the vapours are free to pass from the fuel tank top 81 to the vapour housing through the passage 82.

[00021] As shown in Figure 9, figure 9 shows the fuel tank 2 during banking turning • or roll over. During these three conditions, the fueLtankTinstead-:of-being vertical, tilts with respect to vertical with' an angle due to which one of the floats comes in contact with the liquid fuel. As soon as the float comes in contact with the liquid fuel, due to Archimedes principle the floats experience a buoyant force and are lifted upwardly.

[00022] Due to the conical profile of the float, when the floats are lifted upwards, the diameter of the conical float matches with the diameter of the float holes 61 and fuel is restricted from passing from the fuel tank to the vapour housing 32 of the vapor tapping mechanism 22. As shown in the Figure 9, it can be seen that the Float doesn't allow the fuel vapours to pass through the float into the vapor housing 32 and the liquid fuel is returned to the fuel tank 92.

[00023] ■ Figure 9 shows vapour trapper 22, fuel tank inner 24, fuel tank inside 25, fuel tank inside top 81, vapour blocking illustration 92 and vapour passage illustration 93. In this case of banking, turning or roll over the vapours still can pass to the vapour housing 32 through the path 93. Thus the current invention describes a low .cost and simple system of vapor tapping which integrates the roll over mechanism into the vapor tapping housing.

We claim:

1. A system for vapour tapping for a two-wheeled vehicle (10) comprising:
a fuel tank (2) which stores fuel inside it and fuel vapours on its top portion;"

a vapor trapper (22) on top for trapping the fuel vapours;

characterized in that:

the said vapour trapper further comprises of a vapour chamber (32) and has atleast one float (34) inserted through atleast one gap on the lower surface (43) of the said vapour chamber (32); the said plurality of floats (34) slid-able inside the said gaps; the gaps allowing vapours to get collected in the said vapour chamber (32) during normal vehicle running condition;

and the said plurality of floats (34) when in contact with liquid fuel during vehicle roll over, get buoyed, and block the said gap to inhibit flow of liquid fuel to the said vapour chamber (32).

2. The system for vapour tapping as claimed in Claim 1 has a plurality of floats (34) inserted through plurality of gaps on the lower surface (43) of the said vapour chamber (32).

3. The system for vapour tapping as claimed in Claim 1 wherein the said float (34) has preferably a flat base (52), a conical stem (42); and plurality of fins (44); the fins (44) further being separated by a fin gap (51).

4. The system for vapour tapping Claimed in Claim 1 and Claim 3 has preferably a conical stem (42); the conical stem (42) has a greater diameter near base (52) and lesser diameter on fin end (44).

5. The system for vapour tapping as claimed in Claim 1 wherein the said vapor trapper (22) is preferably in top portion of the said fuel tank and transfers the vapours to a canister through'a hose (33).