TECHNICAL FIELD

[0001] The present subject matter relates generally to fuel supply system for three wheeled vehicles and more particularly, but not exclusively, to evaporative emission control system for three wheeled vehicles.

BACKGROUND

[0002] Generally, internal combustion (IC) engines require air intake, fuel, and spark ignition to achieve combustion. Atmospheric air is drawn in when a vacuum is created in cylinders during an intake stroke of the IC engine. Further, the atmospheric pressure outside also ensures that air is available as and when required by the IC engines. The air that is drawn in is appropriately mixed with the fuel from a fuel storage device, for example, a fuel tank, and the resulting air-fuel mixture is supplied to combustion chamber of the IC engine. A system that controls the air drawn in and the air supplied to the IC engine for combustion is commonly referred to as an air intake system, while a system that controls the fuel supplied to the IC engine is referred to as fuel supply system.

[0003] Generally, the fuel supply system of IC engines includes the fuel tank, a fuel pump, a fuel filter, plurality of hoses for routing fuel to the IC engine, and optionally a fuel injecting device for injecting the air-fuel mixture into an intake manifold of said IC engine.

[0004] For example, in case of spark ignition IC engines using gasoline or petrol as fuel, the fuel supply system is further enabled to control evaporative emissions. Generally, evaporative emission is caused by direct evaporation of hydrocarbon vapours from the plurality of components of the fuel supply system. Recently, the evaporative emission control system, also called as 'EVAP' gained significance after the introduction of regulations insisting for norms on evaporative emission across the globe.

[0005] Generally, such evaporative emissions caused due to direction evaporation of hydrocarbon vapours leads to smog formation, which have a direct impact on health effects. For example, formation of smog may cause damage to human respiratory system by causing choking, coughing, and by reducing lung capacity.

[0006] Conventionally, hydrocarbon evaporation from automobiles are caused due to a plurality of losses, for example, diurnal breathing loss that is caused due to variation in ambient temperature, hot soak loss that is caused due to transfer of heat from high temperature zones of an automobile such as an IC engine, especially when the vehicle is kept in parked condition after an end of a trip. Similar losses known in the art also includes running losses, which are due to generation of vapours when the IC engine is in running condition, and refuelling losses, that causes fuel vapours from the fuel tank to escape into the atmosphere during the process of refuelling of the fuel tank.

[0007] Conventional evaporative emission control measures are affected by various factors such as design of vehicle and particularly fuel supply system of the vehicle, variation in ambient temperature, volatility of gasoline, and other reasons including average trip distance, parking time, parking location, duration of parking under direct sunlight etc.

[0008] Generally, automobiles, in particular, four-wheeled vehicles are known to contain an EVAP system that prevents escape of hydrocarbon vapours into the atmosphere both during vehicle running and parking conditions. For example, such systems enable collection of emitted fuel vapours from the fuel tank followed by re-burning of collected fuel vapours by transmitting the fuel vapours to the IC engine so as to prevent atmospheric pollution caused due to emission of such hydrocarbon vapours. Generally known techniques of adsorption of emitted hydrocarbon vapors include use of devices such as a canister that contains activated carbon.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to reference like features and components.

[00010] FIG. 1 illustrates a perspective view of a frame structure of a three-wheeled vehicle, in accordance with an embodiment of the present subject matter.

[00011] FIG. 2 illustrates a top view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system in accordance with an embodiment of the present subject matter.

[00012] FIG. 3 illustrates a top view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system in accordance with another embodiment of the present subject matter.

[00013] FIG. 4 illustrates a top view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system in accordance with yet another embodiment of the present subject matter.

[00014] FIG. 5 illustrates a rear view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system in accordance with a further embodiment of the present subject matter.

[00015] FIG. 6 illustrates a rear view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system in accordance with a still further embodiment of the present subject matter.

DETAILED DESCRIPTION

[00016] Generally, the EVAP system prevents the escape of fuel vapors to the atmosphere under hot soak and even during engine off conditions by storing the fuel vapors in a fuel adsorbing device, typically known as canister. The system also controls the purging of the stored fuel vapors from the canister to the engine, where they are further burned in the combustion chamber and thereby enabling effective combustion of fuel.

[00017] Typically, canisters are devices found in automobiles enabling decrease of the amount of air pollution the vehicle creates while at the same time helping in enhancing the fuel efficiency of the vehicle. Even when the vehicle's engine is turned off, a certain minimal quantity of hydrocarbon in the form fuel vapors are produced. The canisters trap the fuel vapors rising out of the fuel tank rather than allow it to escape to the atmosphere. Further, the canisters are provided with features that enable them to feed the adsorbed fuel vapors back into the engine for further combustion.

[00018] The canister is characteristic of storing fuel vapors escaping out of the stored fuel inside the fuel tank during engine-off and engine-running conditions. For example, the same is achieved when the activated carbon particles stored inside the canister adsorbs the fuel vapors escaping from the fuel tank. After adsorption of fuel vapors, any quantity of air inside the canister is vented out to the atmosphere through a vent provided on the surface of the canister body. [00019] The canister is generally capable of storing fuel vapors for as long as required till a point they are purged out to the engine for further combustion. For example, during a suction stroke of the IC engine, the sudden suction created along the intake manifold of the IC engine causes purging of fuel vapors out from the canister and towards the IC engine for further burning. During purging, atmospheric air at ambient condition enters the canister through the vent provided on the surface of the canister body and carries the adsorbed hydrocarbon particles from the activated carbon.

[00020] Typically, working and performance of canisters are largely influenced by the design of vehicle that includes the layout of fuel supply system, in particular, the layout provided specifically keeping in mind the location and positioning of evaporative emission control system including canister of the fuel supply system in the vehicle. Most often, optimizing the location and position of the evaporative emission control system layout enables effective emission control and enhancing the fuel efficiency.

[00021] Further, providing an optimal location and position for the evaporative emission control system in the vehicle layout also ensures that the evaporative emission control system is not affected due to day to day variations in ambient temperature.

[00022] Furthermore, providing an optimal location and position of the elements of the evaporative emission control system, for example, the canister becomes increasingly important, as mounting the canister in very high temperature zones in the vehicle cabin may impact the proper functioning of the canister. For instance, very high temperature zones may lead to inadequate collection of fuel vapors in the canister during day to day variations in ambient temperature. This in turn will cause more emissions arising out of the system leading to the aforementioned problems.

[00023] The present subject matter provides an optimal location and positioning of the elements of the evaporative emission control system including the canister inside the vehicle layout and enable overcoming the above mentioned problems associated with mounting the canister in very high temperature zones. Further, the present subject matter, in particular, provides an optimal location and positioning of the canister ensuring mounting of the canister in optimal temperature zones ensuring effective adsorption of fuel vapors by the activated carbons provided within the canister. The same is achieved by ensuring that the canister is mounted in the vicinity of the fuel tank, in particular, towards rightward of the fuel tank, or on the seat base middle.

[00024] In an embodiment, mounting the canister in low temperature zones is possible by positioning the canister and the other devices of the evaporative emission control system in appropriate location inside the vehicle layout. For example, positioning the canister in the vicinity of the fuel tank helps in ensuring the canister remains in low temperature zones. In an embodiment, in the vehicle layout, for example, in a layout of a three-wheeled vehicle, the fuel tank is located on the top left end inside the cabin assembly of the three-wheeled vehicle, when viewed from rear of the three-wheeled vehicle.

[00025] In one implementation, the canister is mounted on the vicinity of the fuel tank that includes substantially rightward disposition, or substantially rearward disposition of the canister with respect to the position of the fuel tank when viewed from the rear side of the three-wheeled vehicle. In another implementation, the canister is capable of being mounted substantially upward of the fuel tank when viewed from the rear side of the three-wheeled vehicle. [00026] In an embodiment, the evaporative emission control system for a three-wheeled vehicle of the present subject matter includes an internal combustion engine that is mounted rearwardly of the three-wheel vehicle. The engine is disposed in a space substantially downwardly of one or more cabin mounting towers. In an implementation, the cabin mounting towers are U-shaped structural members that are mounted on longitudinal members of the three-wheeled vehicle frame. In one embodiment, the engine is substantially mounted between the two longitudinal members of the three-wheeled vehicle. Further, in one embodiment, the engine in the vehicle layout provided by the present subject matter is mounted substantially rearwardly of at least one cross member, which is disposed transversely to a longitudinal axis of the three-wheeled vehicle. Furthermore, in one embodiment, the engine of the present subject matter is mounted substantially rearwardly of an upwardly disposed frame member, for example, a seat base middle.

[00027] Further, in an embodiment, the control system further includes a fuel tank disposed substantially rearwardly of the seat base middle. In an implementation, the fuel tank is disposed substantially forwardly of the one or more cabin mounting towers.

[00028] In one embodiment, the evaporative emission control system further includes an evaporative emission control device; for example, the evaporative emission control device is a canister. In one embodiment, the canister enables treating of fuel vapors expelling from the fuel tank disposed substantially upward of the engine in a vicinity of the fuel tank. Further, in an embodiment, the canister is disposed substantially rightward or substantially rearward of the fuel tank. [00029] In an embodiment, the seat base middle includes at least one horizontal member disposed lengthwise along a vehicle width direction, and at least one vertical member connecting the at least one horizontal member and a longitudinal member of the vehicle in a vehicle up-down direction.

[00030] In another embodiment, the canister is mounted on a bottom surface of the horizontal member of the seat base middle. Further, a longitudinal axis of the canister is displaced substantially parallel to a ground surface in a vehicle length direction. The canister is disposed substantially upwardly of the fuel tank. [00031] In another embodiment, the canister is mounted on a rearward surface of the at least one vertical member of the seat base middle. The longitudinal axis of the canister is displaced substantially inclined to a transverse axis of the vehicle that is perpendicular to a ground surface in a vehicle up-down direction. Further, the canister is disposed substantially rightward of the fuel tank. [00032] In yet another embodiment, the canister is mounted on a rearward surface of the fuel tank facing at least one vertical member of the seat base middle. The longitudinal axis of the canister is displaced substantially inclined to a transverse axis of the vehicle that is perpendicular to a ground surface in a vehicle up-down direction.

[00033] In yet another embodiment, the canister is mounted on a rightward surface of the fuel tank facing an air cleaner of the vehicle. The longitudinal axis of the control device is displaced substantially parallel to a ground surface in a vehicle width direction. Further, at least a transistorized coil ignition (TCI) cover is disposed in a space between the canister and the air cleaner. [00034] In yet another embodiment, the canister is mounted on a rearward surface of the at least one vertical member of the seat base middle. The longitudinal axis of the canister is displaced substantially inclined to a transverse axis of the vehicle that is perpendicular to a ground surface in a vehicle up-down direction. Further, the transistorized coil ignition (TCI) cover is disposed in a space between the canister device and the air cleaner.

[00035] Further, in one embodiment, the evaporative emission control system further includes at least one roll-over valve for receiving fuel vapors expelling from the fuel tank through at least a first hose connecting the fuel tank to the roll¬over valve. The roll-over valve prevents passage of fuel along with the fuel vapors. Furthermore, the fuel vapors exiting out of the roll-over valve is expelled to the canister through at least a second hose connecting the roll-over valve to the canister.

[00036] Furthermore, in one embodiment, the fuel vapors from the canister are collected by at least a purge valve through at least a third hose connecting the canister to the purge valve. In an embodiment, the purge valve pulls the fuel from the canister during a suction stroke of the internal combustion engine and transfers to the internal combustion engine through at least a fourth hose. [00037] The present subject matter and its equivalent thereof offer many advantages, including those, which have been described henceforth. The evaporative emission control system of the present subject matter provides an optimal location and positioning of the canister and the other cooperative components of the evaporative emission control system including roll-over valve and purge valve. Further, the positioning of the components of the evaporative emission control system in optimal location, enables the vehicle layout to achieve mounting of the canister in optimal low temperature zones, which influences an enhanced fuel efficiency and reduced emission levels. Furthermore, the positioning of the canister around the vicinity of the fuel tank ensures ease of assembly of the other related components of the evaporative emission control system. It also enable achieving moderate hose lengths for transferring fuel vapors from the EVAP components of the vehicle to the IC engine. Moreover, the optimal location of the canister mounting is achieved without modifying the existing components in the cabin assembly of the three-wheeled vehicle. Furthermore, the optimized location of the canister also ensures that the fuel vapors are adsorbed and stored in a location that is away from high temperature zones.

[00038] These and other advantages of the present subject matter would be described in greater detail in conjunction with the figures in the following description.

[00039] FIG. 1 illustrates a perspective view of a frame structure of a three-wheeled vehicle, in accordance with an embodiment of the present subject matter. The frame structure 100 of the three-wheeled vehicle depicts a chassis 124 of the three-wheeled vehicle that includes a cabin assembly 112 on the rear side of the three-wheeled vehicle. In an embodiment, the frame structure 100 of the three-wheeled vehicle includes three compartments. A front compartment including a head tube 128 that mounts a handle bar assembly (not shown) of the three-wheeled vehicle, a main tube 126 that connects the head tube 128 and the chassis 124 and a driver seat assembly (not shown) that is housed on top of the chassis 124. In one embodiment, the frame structure 100 further includes a middle compartment that includes a seat base bottom housed on top of a plurality of longitudinal members 118. The seat base bottom of the middle compartment generally enables seating of passengers or occupants of the three-wheeled vehicle. Further, in one embodiment, the frame structure 100 also includes a rear compartment that houses the cabin assembly 112.

[00040] In one embodiment, the cabin assembly 112 of the present subject matter houses an internal combustion (IC) engine 102 and the other driving components of the three-wheeled vehicle. In an embodiment, the IC engine 102 is a spark ignition engine. Further, in one embodiment, the cabin assembly 112 includes a fuel tank 108 disposed upwardly leftward of the cabin assembly 112 when viewed from the rearside of the three-wheeled vehicle. [00041] In an embodiment, the evaporative emission control system of the present subject matter includes other ancillary components that are functionally interconnected with the fuel tank 108. These components include the canister (not shown). In an embodiment, the canister is mounted in the vicinity of the fuel tank 108. In an embodiment, the monting location and positioning of the canister impacts the evaporative emission control system of the present subject matter. Further, the cabin assembly 112 also includes an air cleaner 106 disposed upwardly and rightward of the IC engine 102.

[00042] In one embodiment, the cabin assembly 112 includes the longitudinal members 118 extending on both left and right sides of the cabin. In an embodiment, the cabin assembly 112 further includes a cabin mounting tower including at least one horizontal member 110 and one or more vertical members 116. For example, the one or more vertical members 116 extends vertically upwardly from the top surface of the one or more longitudinal members 118. The top ends of the vertical members 116 are connected by at least one horizontal member 110. In an embodiment, the seat base bottom of the middle compartment has an elongated member that extends inside the cabin assembly 112. The elongated member is a seat base middle 114.

[00043] In an embodiment, the fuel tank 108 and the air cleaner 106 are disposed on both left and right ends of the cabin assembly 112 respectively between the seat base middle 114 and the cabin mounting towers 110, 116. In one embodiment, the one or more longitudinal members 118 of the cabin assembly are horizontally connected by at least one cross member 122. Further, in one embodiemnt, the IC engine 102 is disposed underneath the horizontal member 110 of the one or more cabin mounting towers 110, 116 and placed in the space available between the two longitudinal members 118. In one embodiment, the IC engine 102 is located rearwardly of the cross member 122. [00044] FIG. 2 illustrates a top view of the cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system 200 in accordance with an embodiment of the present subject matter. In one embodiment, the evaporative emission control system 200 includes an evaporative emission control device, for example, a canister 212 is optimally located in the vicinity of the fuel tank 208. For instance, the canister 212 is disposed upwardly to the fuel tank 208 when viewed from the rearside of the three-wheeled vehicle.

[00045] In one embodiment, the canister 212 is mounted on the cabin seat base middle 226. In particular, the canister 212 is mounted on a horizontal member of the cabin seat base middle 226 in a direction that is substantially parallel to the ground surface and disposed with its longitudinal axis extending in vehicle length direction. Such a mounting location of the canister 212 enable optimal location that ensures the canister 212 is located in a low temperature zone in the vicinity of the fuel tank 208 and further enhances serviceability of the fuel supply system components.

[00046] In an embodiment, the fuel vapors escaping out of the fuel tank 208 are routed to a roll-over valve 216 through a first hose 214, for example, a hose connecting the fuel tank and the roll-over valve 216. The roll-over valve 216 is a one-way valve that prevents the passage of fuel further downstream into the canister 212 and allowing only fuel vapors to pass-by. In an embodiment, the roll-over valve 216 is mounted on to a vertical member of the cabin mounting tower 210 that is adjacent to the fuel tank 208.

[00047] Further, in one embodiment, the fuel vapors from the roll-over valve 216 are transmitted to the canister 212 through a second hose 218, for example, a hose connecting the roll-over valve 216 and the canister 212. In an embodiment, the canister 212 contains activated carbon that adsorbs the fuel vapors entering the canister 212. The positioning of the canister 212 adjoining the fuel tank 208 enables effective adsorption of escaping fuel vapors by the canister 212. [00048] In one embodiment, when the IC engine 202 begins suction of fuel, a purge valve 222, for example, a solenoid valve is activated for collection of fuel vapors from the canister 212. During this stage, the fuel vapors stored in the canister 212 are transmitted by an ambient air that is allowed to enter the canister 212 through at least one vent that is provided on the outer surface of the canister 212. The fuel vapors are carried by the incoming ambient air from the canister 212 through a third hose 220 that connects the canister 212 and the purge valve 222. The purge valve 222 opens up and pulls all the fuel vapors out of the canister 212 and sends across to an intake manifold of the IC engine 202 for futher combustion. In an embodiment, the fuel vapors are sent to the IC engine 202 from the purge valve 222 through a fourth hose 224 that connects the purge valve 222 and the engine 202, for example, to a carburettor 204. In one embodiment, the fuel from the purge valve 222 is sent as a mixture of both fuel vapors and fuel as a result of cooling of incoming fuel vapors at the purge valve 222. In another embodiment, an engine control module (not shown) controls the opening and closing of the purge valve 222 depending on the suction created along the intake manifold of the IC engine 202.

[00049] FIG. 3 illustrates a top view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system 300 in accordance with another embodiment of the present subject matter. In one embodiment, the evaporative emission control system 300 includes an evaporative emission control device, for example, a canister 312 that is optimally located in the vicinity of the fuel tank 308. For instance, the canister 312 is disposed rightwardly to the fuel tank 308 when viewed from the rearside of the three-wheeled vehicle. [00050] In one embodiment, the canister 312 is mounted towards a rightside of the fuel tank 308 on a vertical member of the cabin seat base middle 326. For example, the canister 312 is mounted on a rearward surface of the vertical member that extending downwardly from the horizontal member of the cabin seat base middle 326 that is facing the IC engine 302. In particular, the canister 312 is mounted on the rearward facing surface of the cabin seat base middle 326 in a direction that is substantially inclined to the transverse axis that is perpendicular to the ground surface and disposed with its longitudinal axis extending in vehicle up-down direction. Such a mounting location of the canister 312 enable optimal location that ensures low temperature vicinity for the canister 312 and that enhances functioning of the canister 312 and the serviceability of the fuel supply system components.

[00051] In an embodiment, the fuel vapors escaping out of the fuel tank 308 are routed to a roll-over valve 316 through a first hose 314, for example, a hose connecting the fuel tank and the roll-over valve 316. The roll-over valve 316 is a one-way valve that prevents the passage of fuel further downstream into the canister 312 and allowing only fuel vapors to pass-by.

[00052] Further, in one embodiment, the fuel vapors from the roll-over valve 316 are transmitted to the canister 312 through a second hose 318, for example, a hose connecting the roll-over valve 316 and the canister 312. In an embodiment, the canister 312 contains activated carbon that adsorbs the fuel vapors entering the canister 312. The positioning of the canister 312 adjoining the fuel tank 308 enables effective adsorption of escaping fuel vapors by the canister 312. [00053] In one embodiment, when the IC engine 302 begins suction of fuel, a purge valve 322, for example, a solenoid valve is activated for collection of fuel vapors from the canister 312. During this stage, the fuel vapors stored in the canister 312 are transmitted by an ambient air that is allowed to enter the canister 312 through at least one vent that is provided on the outer surface of the canister 312. The fuel vapors are carried by the incoming ambient air from the canister 312 through a third hose 320 that connects the canister 312 and the purge valve 322. The purge valve 322 opens up and pulls all the fuel vapors out of the canister 312 and sends across to an intake manifold of the IC engine 302 for futher combustion. In an embodiment, the fuel vapors are sent to the IC engine 302 from the purge valve 322 through a fourth hose 324 that connects the purge valve 322 and the engine 302, for example, to a carburettor 304. In one embodiment, the fuel from the purge valve 322 is sent as a mixture of both fuel vapors and fuel as a result of cooling of incoming fuel vapors at the purge valve 322. [00054] FIG. 4 illustrates a rear view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system 400 in accordance with yet another embodiment of the present subject matter. In one embodiment, the evaporative emission control system 400 includes an evaporative emission control device, for example, a canister 412 is optimally located in the vicinity of the fuel tank 408. For instance, the canister 412 is disposed rightwardly to the fuel tank 408 when viewed from the rearside of the three-wheeled vehicle. [00055] In one embodiment, the canister 412 is mounted on a surface extending rightwardly of the fuel tank 408. In particular, the canister 412 is mounted on a vertical surface of the fuel tank 408 in a direction that is substantially perpendicular to the ground surface with its longidutinal axis extending in a vehicle up-down direction. Further, the canister 412 is disposed facing the vertical member of the cabin seat base middle in such a manner that the canister 412 is sandwiched in a space formed between the rightward end of the fuel tank 408 and the vertical member sloping downwardly rearward from the horizontal member of the cabin seat base middle when viewed from the rearside of the three-wheeled vehicle. Such a mounting location of the canister 412 ensures that the canister 412 is stored in a very low temperature zone and the optimal location also enhances serviceability of the fuel supply system components and enable ease of assembly of the components of the fuel supply system within the cabin assembly. [00056] In an embodiment, the fuel vapors escaping out of the fuel tank 408 are routed to a roll-over valve 416 through a first hose 414, for example, a hose connecting the fuel tank and the roll-over valve. The roll-over valve 416 is a one¬way valve that prevents the passage of fuel further downstream into the canister 412 and allowing only fuel vapors to pass-by.

[00057] Further, in one embodiment, the fuel vapors from the roll-over valve are transmitted to the canister 412 through a second hose 418, for example, a hose connecting the roll-over valve and the canister 412. In an embodiment, the canister 412 contains activated carbon that adsorbs the fuel vapors entering the canister 412. The positioning of the canister 412 adjoining the fuel tank 408 enables effective adsorption of escaping fuel vapors by the canister 212. [00058] In one embodiment, when the IC engine 402 begins suction of fuel, a purge valve 422, for example, a solenoid valve is activated for collection of fuel vapors from the canister 412. During this stage, the fuel vapors stored in the canister 412 are transmitted by an ambient air that is allowed to enter the canister 412 through at least one vent that is provided on the outer surface of the canister 412. The fuel vapors are carried by the incoming ambient air from the canister 412 through a third hose 420 that connects the canister 412 and the purge valve 418. The purge valve 422 opens up and pulls all the fuel vapors out of the canister 412 and sends across to an intake manifold of the IC engine 402 for futher combustion. In an embodiment, the fuel vapors are sent to the IC engine 402 from the purge valve 422 through a fourth hose 424 that connects the purge valve 422 and the engine 402, for example, to a carburettor 404. In one embodiment, the fuel from the purge valve 422 is sent as a mixture of both fuel vapors and fuel as a result of cooling of incoming fuel vapors at the purge valve 422. [00059] FIG. 5 illustrates a rear view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system 500 in accordance with a further embodiment of the present subject matter. In one embodiment, the evaporative emission control system 500 includes an evaporative emission control device, for example, a canister 512 is optimally located in the vicinity of the fuel tank 508. For instance, the canister 512 is disposed rightwardly to the fuel tank 508 when viewed from the rearside of the three-wheeled vehicle and leftwardly of a TCI cover 528.

[00060] In one embodiment, the canister 512 is mounted on the fuel tank 508. In particular, the canister 512 is mounted on a rightwardly disposed vertical surface of the fuel tank 508 in a direction that is substantially parallel to the ground surface and disposed with its longitudinal axis extending in vehicle width direction. In one embodiment, the canister 512 is disposed rightwardly of the fuel tank 508 when viewed from the rear side of the three-wheeled vehicle. In one implementation, the canister 512 is sandwiched in a space existing between the fuel tank 508 and the TCI cover 528. Such a mounting location of the canister 512 ensures that the canister 512 is consistently maintained at low temperature and the proposed optimal location enhances serviceability of the fuel supply system components. The optimal location also enables easy assembly of components of the fuel supply system.

[00061] In an embodiment, the fuel vapors escaping out of the fuel tank 508 are routed to a roll-over valve 516 through a first hose 514, for example, a hose connecting the fuel tank and the roll-over valve 516. The roll-over valve 516 is a one-way valve that prevents the passage of fuel further downstream into the canister 512 and allowing only fuel vapors to pass-by. In an embodiment, the roll-over valve 516 is mounted on the fuel tank 508.

[00062] Further, in one embodiment, the fuel vapors from the roll-over valve 516 are transmitted to the canister 512 through a second hose 518, for example, a hose connecting the roll-over valve 516 and the canister 512. In an embodiment, the canister 512 contains activated carbon that adsorbs the fuel vapors entering the canister 512. The positioning of the canister 512 adjoining the fuel tank 508 enables effective adsorption of escaping fuel vapors by the canister 512. [00063] In one embodiment, when the IC engine 502 begins suction of fuel, a purge valve 522, for example, a solenoid valve is activated for collection of fuel vapors from the canister 512. During this stage, the fuel vapors stored in the canister 512 are transmitted by an ambient air that is allowed to enter the canister 512 through at least one vent that is provided on the outer surface of the canister 512. The fuel vapors are carried by the incoming ambient air from the canister 512 through a third hose 520 that connects the canister 512 and the purge valve 522. The purge valve 522 opens up and pulls all the fuel vapors out of the canister 512 and sends across to an intake manifold of the IC engine 502 for futher combustion. In an embodiment, the fuel vapors are sent to the IC engine 502 from the purge valve 522 through a fourth hose 524 that connects the purge valve 522 and the engine 502, for example, to a carburettor 504. In one embodiment, the fuel from the purge valve 522 is sent as a mixture of both fuel vapors and fuel as a result of cooling of incoming fuel vapors at the purge valve 522. [00064] FIG. 6 illustrates a rear view of a cabin assembly of a three-wheeled vehicle depicting an evaporative emission control system 600 in accordance with a still further embodiment of the present subject matter. In one embodiment, the evaporative emission control system 600 includes an evaporative emission control device, for example, a canister 612 is optimally located in the vicinity of the fuel tank 608. For instance, the canister 612 is disposed rightwardly to the fuel tank 208 when viewed from the rearside of the three-wheeled vehicle. [00065] In one embodiment, the canister 612 is mounted on a vertical member extending downwardly rearward from a horizontal member of the cabin seat base middle 626. In particular, the canister 612 is mounted on a rearward surface of the vertical member of the cabin seat base middle 626 that is facing the IC engine 602. in a direction that is substantially parallel to the ground surface and disposed with its longitudinal axis extending in vehicle width direction. Such a mounting location of the canister 612 ensures that the canister 612 is sandwiched between the fuel tank 608, the vertical member of the cabin seat base middle 626 and the TCI cover 628, thereby enabling the canister 612 to be consistently maintained in a low temperature zone and the optimal location also enhances serviceability of the fuel supply system components.

[00066] In an embodiment, the fuel vapors escaping out of the fuel tank 608 are routed to a roll-over valve 616 through a first hose 614, for example, a hose connecting the fuel tank and the roll-over valve 616. The roll-over valve 616 is a one-way valve that prevents the passage of fuel further downstream into the canister 612 and allowing only fuel vapors to pass-by. In an embodiment, the roll-over valve 616 is mounted on to a vertical member of the cabin mounting tower 610 that is adjacent to the fuel tank 608.

[00067] Further, in one embodiment, the fuel vapors from the roll-over valve 616 are transmitted to the canister 612 through a second hose 618, for example, a hose connecting the roll-over valve 616 and the canister 612. In an embodiment, the canister 612 contains activated carbon that adsorbs the fuel vapors entering the canister 612. The positioning of the canister 612 adjoining the fuel tank 608 enables effective adsorption of escaping fuel vapors by the canister 612. [00068] In one embodiment, when the IC engine 602 begins suction of fuel, a purge valve 622, for example, a solenoid valve is activated for collection of fuel vapors from the canister 612. During this stage, the fuel vapors stored in the canister 612 are transmitted by an ambient air that is allowed to enter the canister 612 through at least one vent that is provided on the outer surface of the canister 612. The fuel vapors are carried by the incoming ambient air from the canister 612 through a third hose 620 that connects the canister 612 and the purge valve 622. The purge valve 622 opens up and pulls all the fuel vapors out of the canister 612 and sends across to an intake manifold of the IC engine 602 for futher combustion. In an embodiment, the fuel vapors are sent to the IC engine 602 from the purge valve 622 through a fourth hose 624 that connects the purge valve 622 and the engine 602, for example, to a carburettor 604. In one embodiment, the fuel from the purge valve 622 is sent as a mixture of both fuel vapors and fuel as a result of cooling of incoming fuel vapors at the purge valve 622. [00069] Although the subject matter has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. It is to be understood that the appended claims are not necessarily limited to the features described herein. Rather, the features are disclosed as embodiments of the frame structure 100 of the three-wheeled vehicle and the evaporative emission control system 200, 300, 400, 500, 600.

1/ we claim:

1. An evaporative emission control system (200, 300, 400, 500, 600) for a three-wheeled vehicle comprising: an internal combustion engine (102) mounted rearwardly of said vehicle, said engine (102) disposed in a space substantially downwardly of one or more cabin mounting towers (110, 116), substantially between two longitudinal members (118) of said vehicle, substantially rearwardly of at least one cross member (1220 disposed transversely to a longitudinal axis of said vehicle, and substantially rearwardly of an upwardly disposed frame member (114) of said vehicle; a fuel tank (108) disposed substantially rearwardly of said upwardly disposed frame member (114), and substantially forwardly of said one or more cabin mounting towers (110, 116); and an evaporative emission control device (212, 312, 412, 512, 612) for treating fuel vapors expelling from said fuel tank (108) disposed substantially upward and farther from at least a top portion of said engine (102) in a vicinity of at least one upwardly disposed frame member (114), wherein said control device (212, 312, 412, 512, 612) is disposed in at least one of a substantially rightward, substantially rearward, and substantially upward direction of said fuel tank (108) when viewed from a rear side of the vehicle.

2. The evaporative emission control system (200, 300, 400, 500, 600) as claimed in claim 1, wherein said upwardly disposed frame member (114) includes a seat base middle (114) having at least one horizontal member disposed lengthwise along a vehicle width direction, and at least one vertical member connecting said at least one horizontal member of said seat base middle (114) and a longitudinal member (118) of said vehicle in a vehicle up-down direction.

3. The evaporative emission control system (200) as claimed in claim 2, wherein said control device (212) is mounted on a bottom surface of said horizontal member of said seat base middle (226), a longitudinal axis of said control device (212) is displaced substantially parallel to a ground surface in a vehicle length direction, said control device (212) is disposed substantially upwardly of said fuel tank (208).

4. The evaporative emission control system (300) as claimed in claim 2, wherein said control device (312) is mounted on a rearward surface of said at least one vertical member of said seat base middle (326), a longitudinal axis of said control device (312) is displaced substantially inclined to a transverse axis of said vehicle that is perpendicular to a ground surface in a vehicle up-down direction, and wherein said control device (312) is disposed substantially rightward of said fuel tank (308).

5. The evaporative emission control system (400) as claimed in claim 2, wherein said control device (412) is mounted on a rearward surface of said fuel tank (408) facing at least one vertical member of said seat base middle (426), a longitudinal axis of said control device (412) is displaced substantially inclined to a transverse axis of said vehicle that is perpendicular to a ground surface in a vehicle up-down direction.

6. The evaporative emission control system (500) as claimed in claim 1, wherein said control device (512) is mounted on a rightward surface of said fuel tank (508) facing an air cleaner (506) of said vehicle, a longitudinal axis of said control device (512) is displaced substantially parallel to a ground surface in a vehicle width direction, wherein at least a transistorized coil ignition (TCI) cover (528) is disposed in a space between said control device (512) and said air cleaner (506) of said vehicle.

7. The evaporative emission control system (600) as claimed in claim 2, wherein said control device (612) is mounted on a rearward surface of said at least one vertical member of said seat base middle (626), a longitudinal axis of said control device (612) is displaced substantially inclined to a transverse axis of said vehicle that is perpendicular to a ground surface in a vehicle up-down direction, wherein at least a transistorized coil ignition (TCI) cover (628) is disposed in a space between said control device (612) and said air cleaner (606) of said vehicle.

8. The evaporative emission control system (200, 300, 400, 500, 600) as claimed in one of the preceding claims further comprising: at least one roll-over valve (216) for receiving fuel vapors expelling from said fuel tank (208) through at least a first hose (214) connecting said fuel tank (208) to said roll-over valve (216), wherein said roll-over valve (216) prevents passage of fuel along with said fuel vapors, and wherein said fuel vapors from said roll-over valve (216) is expelled to said control device (212) through at least a second hose (218) connecting said roll-over valve (216) to said control device (212).

9. The evaporative emission control system (200, 300, 400, 500, 600) as claimed in claim 8, wherein said fuel vapors from said control device (212) is collected by at least a purge valve (222) through at least a third hose (220) connecting said control device (212) to said purge valve (222).

10. The evaporative emission control system (200, 300, 400, 500, 600) as claimed in claim 9, wherein said purge valve (222) pulls the fuel from said control device (212) during a suction stroke of said internal combustion engine (202) and transfers to said internal combustion engine (202) through at least a fourth hose (224)'