Claims:We claim:
1. A vehicle (100) comprising:
a frame assembly (105), said frame assembly (105) comprising:
a pair of side tubes (410, 420) extending rearwardly and upwardly from a portion of a cross tube (430),
a pillion foot rest assembly (210) fluidically connected to said pair of side tubes (410,420), said pillion foot rest assembly (210) to communicate cooling air comprising:
one or more pillion foot rest tube (530), and
one or more connecting tube (510);
wherein a first end of said connecting tube (510) being fluidically attached to at least a portion of one of said pillion foot rest tube (530) and a second end of said connecting tube (510) being operatively connected to a CVT cover (220).
2. The vehicle (100) as claimed in claim 1, wherein the frame assembly (105) comprises a head tube (106), and a main tube (107) extending rearwardly and downwardly from said head tube (106) being connected to the cross tube (430).
3. The vehicle (100) as claimed in claim 1, wherein a front-end portion of said pillion foot rest tube (530) being connected to one of said side tube (410) and extending in a lateral direction of said vehicle (100).
4. The vehicle (100) as claimed in claim 3, wherein said front end portion of said pillion foot rest tube (530) attached to a portion of one of said side tube (410) being configured to have one or more openings to allow ingress of fresh air from said side tube (410) towards said pillion foot rest tube (530).
5. The vehicle (100) as claimed in claim 1, wherein said first end of said connecting tube (510) being connected to a portion of said pillion foot rest tube (530) being configured to have one or more openings to allow ingress of fresh air from pillion foot rest tube (530) towards the CVT cover (220) through said connecting tube (510).

6. The vehicle (100) as claimed in claim 1, wherein said second end of said connecting tube (510) being connected to a bellow (303) through an attachment means (305) to connect with said CVT cover (220).
7. The vehicle (100) as claimed in claim 1, wherein said frame assembly (105) includes one or more reinforcement structure (520), said reinforcement structure (520) being connected to a portion of at least one of said pair of side tubes (410, 420).
8. The vehicle (100) as claimed in claim 8, wherein said reinforcement structure (520) being connected to a portion of at least one of said pillion foot rest tube (530).
9. The vehicle (100) as claimed in claim 1, wherein a rear end portion of one of said side tube (410) being configured to have an angular cut opening (540) and a front-end portion of said side tube (410) being connected to a portion of said cross tube (430).
10. The vehicle (100) as claimed in claim 1, wherein said one of said pair of side tubes (410), said one or more pillion footrest tube (530) and said one or more connecting tube (510) is configured to create a fresh air circulation passage to allow ingress of fresh air to the CVT cover (220).
, Description:TECHNICAL FIELD
[0001] The present subject matter generally relates to a cooling arrangement for a continuously variable transmission (CVT) system, and more particularly, relates to a natural cooling arrangement for continuously variable transmission system in a two-wheeled vehicle.

BACKGROUND
[0002] A continuously variable transmission (CVT) system is usually adopted in internal combustion (IC) engines wherein mechanically shifting gears by a rider of a two-wheeled vehicle can be avoided. The CVT system replaces the gear shift transmission mechanism in the IC engine. Generally, IC engine of all two-wheeled vehicles have a transmission system between a crankshaft and the final drive to the wheel of the two-wheeled vehicle to change the ratio between the crankshaft rotational speed and the rotational speed of a wheel to provide speed and torque conversions of the two-wheeled vehicle. While regular geared transmission system requires that the rider of the two-wheeled vehicle manually perform gearshifts, CVT system eliminates this need of performing manual gearshifts by providing automatic change in gear ratios between the crankshaft rotational speed and the rotational speed of the wheel. The CVT system provides almost infinite gear ratios which makes driving very easy, smooth and efficient. The CVT system comprises a driving pulley operably attached to the crankshaft, a driven pulley operably connected to the wheel and a belt that rests between them all of which are enclosed within a crankcase of the IC engine. The driving pulley comprises a variator mechanism and the driven pulley comprises a centrifugal clutch. Different gear ratios are obtained by changing the effective diameter of the driving pulley and the driven pulley while the belt is sitting on them and moving.

BRIEF DESCRIPTION OF DRAWINGS
[0003] The detailed description is described with reference to the accompanying figures, which is related to a two-wheeled vehicle being one embodiment of the present subject matter. However, the present subject matter is not limited to the depicted embodiment(s). In the figures, the same or similar numbers are used throughout to reference features and components.
[0004] Fig. 1 depicts a left-side view of an exemplary two-wheeled vehicle in accordance with an embodiment of the present subject matter.
[0005] Fig. 2 illustrates an enlarged left-side general assembly view of the two-wheeled vehicle in accordance with an embodiment of the present subject matter.
[0006] Fig. 3 illustrates an exploded left-side general assembly view of the essential components of the two-wheeled vehicle in accordance with an embodiment of the present subject matter.
[0007] Fig. 4 illustrates an exploded left-side view of the two-wheeled vehicle in accordance with an embodiment of the present subject matter.
[0008] Fig. 5 illustrates an exploded left-side perspective view of the frame assembly in accordance with an embodiment of the present subject matter.
[0009] Fig. 6 shows an enlarged left-side view of a portion of the frame assembly illustrating the air flow circulation in accordance with an embodiment of the present subject matter.
[00010] Fig. 7 illustrates a right-side perspective view of the frame assembly illustrating the air flow circulation in accordance with an embodiment of the present subject matter.
[00011] Fig. 8 illustrates an enlarged perspective view of a hugging provision in accordance with an embodiment of the present subject matter.
[00012] Fig. 9 illustrates a schematic view of the air flow circulation inside the frame assembly directing air to CVT cover in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION
[00013] Various features and embodiments of the present subject matter here will be discernible from the following further description thereof, set out hereunder. According to an embodiment, an internal combustion (IC) engine described here operates in four cycles. The IC engine is installed in a step through type two-wheeled vehicle colloquially called as scooter. It is pertinent to note that the IC engine may be mounted in two-wheeled vehicles in different arrangements such as in transverse and longitudinal fashion. However, in the ensuing description, such engine is transversely mounted at a lower portion of the step through type two-wheeled vehicle. It is contemplated that the concepts of the present subject matter may be applied to other types of vehicles and other types of IC engine such as that of the two-stroke type within the spirit and scope of this subject matter. The detailed explanation of the constitution of parts other than the present subject matter which constitutes an essential part has been omitted at suitable places.
[00014] Conventionally, two-wheeled vehicle such as a scooter have tubular frames including a front frame and a rear frame. The front frame is used to carry the steering & front suspension and also enables providing stiffness and strength to the two-wheeled vehicle. It generally consists of the main tube running downward and rearward from the housing steering pivot which forms the under-bone zone of the front frame by extending rearward till the rear frame.
[00015] Typically, a swinging IC engine is located below the seat at a lower rear portion of the vehicle. The IC engine is swingably supported by rear suspension system and attached to the frame of the two-wheeled vehicle and the other end of the IC engine is connected to a second wheel of the two-wheeled vehicle. A CVT system forms a part of the IC engine and is disposed on the rear portion of the IC engine and mounted so as to be disposed on right or left of the two-wheeled vehicle. Generally, it is disposed in such a manner so as to be oriented towards the left of the two-wheeled vehicle as viewed from the rear direction of the two-wheeled vehicle. The CVT system is enclosed within a crankcase of the IC engine on the rear side of the IC engine and the CVT system is enclosed by a crankcase cover also called as a CVT cover, thus forming an enclosed space within the CVT cover.
[00016] Further, the rear frame accommodates the powertrain including the engine, the CVT system or a transmission system (hereinafter CVT and transmission system have been used interchangeably) that withstands the payload and rear axle loads. It generally consists of a pair of side tubes extended upwards and rearwards from the end of the front frame. The main tube & the side tubes of the frame are the major load bearing members in the front and rear frame zones of the vehicle and hence requires to possess higher strength & stiffness so as to carry the load of the entire two-wheeled vehicle.
[00017] Herein, the CVT system comprises a driving pulley operably attached to a crankshaft (via gear-train), a driven pulley operably connected to the second wheel (again via another set of gear-train) and a belt that rests between them. The driving pulley and the driven pulley each is made up of two sliding halves with an elastic member applying a positive bias force restricting movement of the rear half of the pulleys. The belt having a fixed length is set between the two halves of the driving pulley and the driven pulley.
[00018] The driven pulley is provided with an inner cylinder coaxially encircling the output shaft so that the output shaft can be relatively rotated on an outer cylinder with which the inner cylinder is slidably engaged so that relative turning around the axis and axial relative movement is possible. The driven pulley is also provided with a fixed pulley half fixed to the inner cylinder; a movable pulley half fixed to the outer cylinder opposite to the fixed pulley half. The V-belt is wound onto a belt groove formed between the fixed pulley half and a movable pulley half of both the pulleys.
[00019] In vehicles with V-belt Continuously Variable Transmission (CVT), frictional heat is generated by frictional contact between the V-belt and the pulleys, namely the driving pulley and the driven pulley during gear changing that takes place with constant movement of the belt on the pulleys which are rotating in themselves. The contact between V-belt sidewalls and the pulleys is the main source of heat generation in CVT systems. Due to generation of this frictional heat, temperature inside the transmission system increases which leads to expansion of the V-belt, which further leads to a desired gear change ratio not being obtained. Frictional heat also leads to deterioration of the V-belt and further affects the service life of pulley and belt due to material degradation. Expansion of belt due to heating results in loss of transmission efficiency and less durability of CVT parts. Moreover, since lubricating the CVT belt and pulleys cannot be an option as the belts would start slipping on the said pulleys and the effective gear ratio would not be achieved, the CVT engines are provided with air cooling from inside.
[00020] Therefore, effective cooling of a V-Belt CVT is necessary to obtain the desired gear ratio as well as to improve the durability of parts of the CVT especially the V-belt.
[00021] Cooling arrangement for CVT systems known in the art generally has its air inlet at the side of the transmission case, towards the engine, near the cooling cowl of the engine. In such an arrangement, due to heat radiated from the engine, the cooling air entering the inlet of the CVT cooling arrangement gets heated up leading to reduction in cooling efficiency. Further, in such an arrangement, dust and muddy water raised by the second wheel can easily enter the air outlet.
[00022] Conventional air intake structures on the CVT cover are generally provided and is a very important criterion as it leads to determining the effective performance and efficiency of the forced air-cooling system. However, the location of the air intake structure on the two-wheeled vehicle as seen from the side view, it is observed that, the air intake structure is disposed very close to the cylinder head, cylinder block and crankcase and utilizes a bellow to let the air pass to the CVT. As it is known that one of the major heat sources in the two-wheeled vehicle is the IC engine, hence, the air around the IC engine main body crankcase is always at an elevated temperature. The positioning of the air intake structure close to the IC engine main body crankcase, facilitates the drawing of this hot air into the CVT system by the cooling fan to cool the CVT components.
[00023] Further, the air intake structure opens into the atmosphere enabling direct access of air entry inside the CVT system. This can allow entry of foreign matter into the CVT system. The foreign matter can include water, mud, and other debris which can cause the belt to slip and wear out faster. Further, the air intake structure comprises an air filter foam disposed slightly downstream of the conventional air intake structure which filters the air. But, entry of water, mud and large particles can damage this air filter foam which results in frequent replacement and damage to CVT components. Since, the air intake structure is located at a point on the two-wheeled vehicle which is very close to the ground level, on movement of the two-wheeled-vehicle over a puddle of water or through areas having lot of mud, the probability of entering the mud and water is higher, which in turn results in increased service intervals of the two-wheeled vehicle.
[00024] Further, such complex arrangement of air intake structures placed near the rear frame of the two-wheeled vehicle utilize multiple elements such as bellows and clamping structures to provide for air flow to the CVT system which results in an overall increase in the weight of the two-wheeled vehicle, thereby increasing the cost of the two-wheeled vehicle as well. Such air intake structures occupy considerable amount of space in the vehicles and further result into interference of CVT air intake structures with nearby parts, thereby affecting the smooth functioning of such surrounding parts and posing the problem of complex packaging of the CVT system. Moreover, arrangements wherein, the cooling system and/or air intake structure is provided in side tubes of the rear frame results in reduced durability of the frame as the rear frame and the side tubes have to withstand the payload and rear axle loads of the two-wheeled vehicle.
[00025] Further, certain attempts have been made to enable ingression of fresh air from frame assembly including side tubes which is connected to the CVT system so that fresh air can circulate in the CVT system using bellows, connecting means such as clips, clamps, attachments and various mounting brackets. However, in such said frame structure, the front frame contains main-tube running downward and rearward from the housing steering pivot and further forms the under-bone zone of front frame by extending rearward till the front end of the rear frame. The rear frame contains, two side tubes which run parallel to each other from rearward of under-bone zone of front frame. The rear frame carries the payload and rear axle load. In such a design, providing additional setup/arrangement with bellows, connecting means, brackets etc. in side tubes for cooling reduces the durability and stiffness of the frame.
[00026] Thus, there arises a need for providing a natural cooling arrangement for efficient cooling of CVT systems that allows fresh air from the atmosphere without the need of any air suction mechanism and prevents entry of water and/or mud inside the CVT system, that further addresses the aforementioned and other problems of the prior art.
[00027] The present subject matter along with all the accompanying embodiments and their other advantages would be described in greater detail in conjunction with the figures in the following paragraphs.
[00028] The present subject matter discloses a vehicle comprising a frame assembly wherein the frame assembly further comprises a head tube, a main tube which is extending rearwardly and downwardly from the head tube. Such main tube is further connected to a cross tube. The frame assembly further comprises a pair of side tubes extending rearwardly and upwardly from a portion of the cross tube and a pillion foot rest assembly fluidically connected to said pair of side tubes to communicate cooling air including one or more pillion foot rest tube, and one or more connecting tube wherein the side tubes is connected to the pillion footrest assembly. The vehicle further comprises a power train including an engine and a transmission assembly. In an embodiment, a first end of the connecting tube is attached to at least a portion of one of the pillion foot rest tube and a second end of the connecting tube is operatively connected to the transmission assembly.
[00029] Further, a front-end portion of said pillion foot rest tube is connected to one of said side tubes wherein the one of the side tubes has one or more openings to allow ingression of fresh air towards the pillion footrest tube. The first end of the connecting tube is further connected to a portion of the pillion foot rest tube which has one or more openings to allow ingression of fresh air from pillion foot rest tube towards the transmission assembly through the connecting tube. The second end of the connecting tube is connected to a bellow through an attachment means to connect with the transmission assembly. Herein, the attachment means includes one or more clamps.
[00030] In another embodiment, the vehicle further includes one or more reinforcement structures connected to a portion of at least one of said pair of side tubes and is also connected to at least one of the pillion foot rest tube. The vehicle also includes one or more toggle link bracket which is connected to a portion of at least one of said pair of side tubes. Moreover, a rear end portion of one of the side tubes have an angular cut opening and a front-end portion of one of the side tubes is connected to a portion of the cross tube.
[00031] Further, according to an embodiment, the present subject matter discloses a frame assembly wherein the frame assembly further comprises a head tube, a main tube which is extending rearwardly and downwardly from the head tube. Such main tube is further connected to a cross tube. The frame assembly further comprises a pair of side tubes extending rearwardly and upwardly from a portion of the cross tube and a pillion foot rest assembly including one or more pillion foot rest tube, and one or more connecting tube. Herein, a first end of the connecting tube is attached to at least a portion of one of the pillion foot rest tube and a second end of the connecting tube is operatively connected to a transmission assembly.
[00032] The present subject matter aims to provide an efficient cooling arrangement for CVT systems that allows dust free air inside the transmission system that further helps in reducing the damage to the CVT parts due to heating, thereby reducing the requirement of frequent servicing of the CVT parts, thus improving the engine performance and increasing the overall service life of the vehicle. Moreover, the present subject matter aims to provide efficient cooling during both driving and stationary mode of the vehicle. The present subject matter achieves the objectives even when the vehicle is operated in minimum velocity or is at rest position since the air present in the vehicle frame body is sufficient enough to cool the CVT system which is circulated through the frame assembly.
[00033] Moreover, it aims to increase the durability of the frame assembly and the pillion footrest assembly of the entire vehicle to possess sufficient stiffness to withstand the payload and rear axle load of the vehicle by providing a simple, light weight frame assembly with non-circular cross section as opposed to circular cross section. Such non-circular cross section results in providing a bigger diameter frame assembly with reduced thickness that results in more amount of fresh air to be channeled inside the CVT system.
[00034] It further aims to provide a compact packaging structure of the entire vehicle by reducing the interference of CVT air intake structures with nearby parts, thereby enabling the smooth functioning of such surrounding parts and eliminating the problem of complex packaging of the CVT system.
[00035] The present subject matter is further described with reference to accompanying figures. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00036] The frame assembly may be implemented in any two-wheeled vehicle or a three-wheeled vehicle. However, for the purpose of explanation and by no limitation, the frame assembly system, and corresponding additional advantages and features are described through the following embodiments. Arrows wherever provided on top right corner of the figure represent direction with respect to vehicle. Arrow F represents forward direction, arrow R represents rearward direction, arrow UW represents upward direction and arrow DW represents downward direction.
[00037] Fig. 1 illustrates a left-side view of an exemplary two-wheeled vehicle (100), in accordance with an embodiment of the present subject matter. The vehicle (100) includes a frame assembly (105) (shown schematically by dotted line) comprising a head tube (106), and a main frame (not shown in figure). In the depicted embodiment, the main frame (not shown in figure) comprises a main tube (107) extending rearwardly downward from the head tube (106), and one or more rear tubes (110) extending inclinedly rearward from a rear portion of the main tube (107). In the depicted embodiment, the frame assembly (105) defines a step-through portion (151), which is used by rider to rest his/her feet or to load luggage thereat. In another embodiment, a main tube (107) may be adapted to extend rearward from the head tube (106) and subsequently downward defining a space below the main tube (107), for supporting a powertrain (135). A first wheel (101) and a second wheel (102) are rotatably supported by a front suspension system (131) and a rear suspension system (134), respectively. In one embodiment, the second wheel (102) may be additionally supported by a swingarm (not shown). As per one aspect of present invention, a cross member termed as rear bridge structure connects the pair of rear frame members. Further, as per one aspect of the present invention, the main frame is mounted to a steering head member of the vehicle and extends downwardly where a step-through portion is connected to the main frame of the vehicle. Further, as per one aspect of the present invention, a cross member step-through portion (151) is mounted in between the pair of step-through portion (151) to provide the strength to the mounting of step-through portion (151).
[00038] In accordance with the present embodiment, a powertrain (135) is swingably connected to the frame member (105) and is disposed substantially below a seat assembly (155) and rearward to the step-through portion (151). The powertrain (135) includes a transmission system (145) for transferring power to the second wheel (102) and an engine (140). The transmission system (145) may include a continuously variable transmission, an automatic manual transmission, a belt/chain drive. In one embodiment, the powertrain (135) is an internal combustion engine. In another embodiment, the powertrain (135) is an electric prime mover. In one another implementation, the powertrain (135) is fixedly mounted to the frame assembly (105) of the vehicle (100).
[00039] The transmission system (145) comprises a driving pulley operably attached to the crankshaft, a driven pulley operably connected to the wheel and a belt connecting the driving pulley and driven pulley wherein said driving pulley, said driven pulley and the beltbeing enclosed within a crankcase of the IC engine. The driving pulley comprises a variator mechanism (not shown in figure) and the driven pulley comprises a centrifugal clutch. According to an embodiment of the present subject matter, a cut-out (not shown in figure) is provided on the cover variator to access a plurality of fasteners. The cut-out on the cover variator is covered by using a cap. Such cap results in easy accessibility of the fasteners as by removing the cap, one is able to access the plurality of fasteners through the cut-out provided on the cover variator.
[00040] The rear zone includes a subframe (not shown in figure) that supports the vehicle parts including the powertrain (135), the second wheel (102), and the rear suspension system (134) connected thereof. Therefore, the rear zone and the front zone are subject to various forces from the second wheel (102) through the suspension and from the powertrain (135) and from the first wheel (101) in addition to the payloads arising out the occupants & goods. Further, the impacts from the road like bumps and vibration from the powertrain (135) are also acting on the frame assembly (105).
[00041] Moreover, the rear suspension assembly utilizes the laws of mechanical physics to dissipate forces acting on the wheels, in order to provide a smooth and stable ride. Each system’s unique geometry and components allow them to function to specific user needs. While the function of suspension is quite clear, the best design to achieve this goal is hardly so apparent. Rear suspension assembly is a mechanical or hydraulic device designed to absorb and damp shock impulses. It does this by converting the kinetic energy of the shock into another form of energy which is then dissipated. The transformation of kinetic energy into heat takes place when a damper piston moves up and down in a cylinder filled with oil. A spring is needed most when driving over an obstacle.
[00042] In an embodiment of the present subject matter, a gas canister (not shown in figure) is mounted on the bottom of the rear shock absorber (not shown in figure). Such gas canister (not shown in figure) can be integrated to the shock absorber (not shown in figure) or fastened to the shock absorber at the bottom of the rear shock absorber. The gas canister enhances the damping performance of the shock absorber and further enhances the style of the vehicle (100) as well.
[00043] Further, the temperature around the cylinder head (not shown in figure) is quite high. The travelling air from the underside of the step-through portion (151) helps in directing the hot air around the cylinder head towards a utility box resulting in heating of said utility box and at times creates discomfort to the driver and pillion rider. Thus, to stop the flow of air from the underside step-through portion (151) to reach the engine, according to an embodiment of the present subject matter, a pair of ribs are provided below the step-through portion (151) to prevent the hot air around the cylinder head (not shown in figure) from reaching to the utility box.
[00044] In yet another embodiment, a flange portion (not shown in figure) is provided on a cover bottom (not shown in figure) of the step-through portion (151) to redirect outside air that falls on the cylinder head. Such cover bottom of the step-through portion (151) is placed below the fuel tank to effectively dissipate the heat generated from the cylinder head that results in heating up of the utility box.
[00045] Moreover, in another embodiment, an air deflector (not shown in figure) is located in the space below the step-through portion (151) and the fuel tank. Such air deflector is mounted on the fuel tank and serves as an air channel to direct the outside air to the cylinder head (not shown in figure) to effectively cool the cylinder.
[00046] Further, the first wheel (101) is pivotally supported by the frame assembly (105) and a handle bar assembly (150) is functionally connected to the first wheel (101) for maneuvering and steering the vehicle (100). The handle bar assembly (150) may support an instrument cluster, vehicle controls including throttle, clutch, or electrical switches. Further, a seat assembly (155) is supported by the frame assembly (105) and the rider can operate the vehicle (100) in a seated position on the seat assembly (155). Moreover, in the depicted embodiment, the vehicle (100) includes the step-through portion (151) formed between the handle bar assembly (150) and the seat assembly (155).
[00047] The vehicle (100) is provided with plurality of panels (170A, 170B, 170C) mounted to the frame assembly (105) and covering the frame assembly (105) and/or parts of the vehicle (100). The plurality of panels includes a front panel (170A) and a leg-shield (170B) covering the head tube (106) of the frame assembly (105) in forward and rearward direction, respectively. Further, a rear panel assembly (170C) is disposed substantially below the seat assembly (155). The rear panel assembly (170C) substantially covers the utility box (not shown) disposed below the seat assembly (155) and also, covering at least a portion of the powertrain (135).
[00048] In addition, a front fender (165) is covering at least a portion of the first wheel (101). In the present embodiment, the front fender (165) is integrated with the front panel (170A). A utility box (not shown) is disposed below the seat assembly (155) and is supported by the frame assembly (105). A fuel tank (not shown) is disposed adjacently to the utility box (not shown). A rear fender (175) is covering at least a portion of the second wheel (102) and is positioned below the fuel tank and upwardly of the second wheel (102).
[00049] According to an embodiment, a telematics unit (not shown in figure) is mounted to a bracket (not shown in figure) wherein the bracket is further mounted to the vehicle (100) using a plurality of bolts. Such bracket is already used for mounting the fuel tank (not shown in figure).
[00050] In another embodiment, a bracket (not shown in figure) is assembled using a plurality of fasteners on the fuel tank (not shown in figure). The step-through portion (151) rests on said bracket and provides support to the step-through portion during usage by the driver.
[00051] In yet another embodiment, a horn is located on the right-side of the main tube of the frame assembly. The horn is mounted on a bracket which is welded to the main frame with the help of fasteners. The location of the horn on the right-side of the main tube of the frame assembly results into improved accessibility during servicing and further provides ease of packaging of other parts in front of the head tube.
[00052] Fig.2 and Fig. 3 illustrates an enlarged left-side general assembly view and an exploded left-side general assembly view of the essential components of the two-wheeled vehicle, according to an embodiment of the present subject matter. The frame assembly (105) includes a pillion footrest assembly (210) fluidically connected to said pair of side tubes (410,420) wherein said pillion foot rest assembly (210) communicates cooling air, further wherein the pillion rider puts his/her foot and a CVT cover (220) that covers the transmission system (145) to protect it from dust, mud and water. The pillion footrest tube (210) is connected to the transmission system (145) through a front end of a clip (301), while the rear end of the clip (301) is fitted to a front portion of a bellow (303). Such rear portion of the bellow (303) is further connected to an attaching means (305) which may be a clamp. Moreover, the attaching means (305) is connected to the transmission system (145) through a top rectangular opening in the CVT cover (220).
[00053] Fig. 4 illustrates an exploded left-side view of a portion of the vehicle and Fig. 5 illustrates an exploded left side perspective view of the frame assembly (105) including a pair of side tubes with left side tube (410) and a right-side tube (420) parallelly connected to each other through a cross tube (430). The frame assembly (105) further includes a toggle link bracket (440) supported directly to the pair of side tubes (410,420) rigidly attached to each side tube to the pair of side tubes (410,420) by welding. As per an embodiment of the present subject matter, the cross tube (430) integrally includes left and right-side arms, left and right inclined arms extending inclinedly rearwardly from said left and right-side arms, and a central arm bridging said left and right inclined arms. The cross tube (430) support said pair of side tubes (410,420). Particularly, said pair of side tubes (410,420) is rigidly supported on end integrally formed on each side arms of said left and right-side arms of the cross tube (430). The frame assembly (105) further comprises of a reinforcement structure (520) which is placed below a pillion footrest tube (530), that is the part of a pillion footrest assembly (210) and a connecting tube (510). A front end of the connecting tube (510) is connected to the pillion footrest tube (530).
[00054] Fig. 6 shows an enlarged left-side view of a portion of the frame assembly (105) illustrating the air flow circulation, according to an embodiment of the present subject matter. The cross tube (430) is securely welded onto a lower portion of one of the side tubes (410) with the reinforcement structure (520) being rigidly welded below the cross tube (430) and onto one of the side tubes (410), thereby forming an overlapped reinforcement structure (610). Such overlapped reinforcement structure is further connected to the pillion footrest assembly (210).
[00055] Further, as per an embodiment of the present subject matter, the pair of side tubes (410) is provided with an opening at the lower end wherein one or more pillion footrest tube may be welded with the toggle link bracket (440) and hence with the pillion footrest assembly (210). The pillion foot rest tube (530) further has an opening wherein it is connected to a first end of the connecting tube (510). Further, the pair of side tubes (410,420) is reliably secured to the cross tube (430) which can be further rigidly secured to the pillion footrest assembly (210) through welding.
[00056] In another embodiment, the pair of side tubes (410,420) may have a circular cross section. Even while using the pair of side tubes (410,420) having a circular cross section, the accuracy of welding is maintained because of the presence of the toggle link bracket (440) and a reinforcement structure (520). The presence of the reinforcement structure (520) along with the toggle link bracket (440) aids in increasing the overall welding accuracy, since the toggle link bracket (440) is welded on the inner surface of the one pair of side tubes (410) and the reinforcement structure is welded on the outer surface of the one of the pair of side tubes (410), thereby improving the stiffness and durability of the frame assembly (105).
[00057] In another embodiment, the toggle link bracket (440) may also be in the form of a cylindrical bush. Providing a cylindrical cross section aids in increasing the length to diameter ratio of the bush. Thus, the welding of the reinforcement structure (520) with the each side tube of the pair of side tubes (410,420) and the toggle link bracket (440) aids to increase the strength of the pair of side tubes (410,420) locally, thereby enhancing rigidity and sturdiness of the pair of side tubes (410,420), hence increasing the stiffness and durability of the entire frame assembly. Such arrangement of the toggle link bracket (440) along with the reinforcement structure (520) is used to support the frame assembly reliably without yielding due to higher load.
[00058] Fig. 7 illustrates a right-side perspective view of the frame assembly (105), illustrating the air flow circulation, according to an embodiment of the present subject matter. The rear end angular cut opening (540) shown in Fig 5 is designed to have bigger cross section than the cross section of side tube (410). The said side tube (410) has a hole (not explicitly shown in figure), which allows the dust free air from angular cut opening (540) of said side tube (410) to enter the pillion footrest assembly (210) in the pillion foot rest tube (530) which also has an opening (not shown in figure) and passes through the connecting tube (510) to the CVT cover (220). The said side tube (410) and the pillion footrest assembly (210) are connected by means of welding, which enables a leak free assembly. The axis of said side tube (410) hole and the pillion footrest tube (530) are collinear, which ensures the smooth air flow into the CVT cover (220) through the connecting tube and bellow (303).
[00059] In another embodiment, the air inside the side tube (410) travels in a circular motion till the end of the side tube (410) and then flows towards pillion footrest tube (510). From the pillion footrest tube (510), the air flows towards the front-end portion of the connecting tube (530) and then travels to the transmission system (145). In another aspect of the invention, there may be a stopping element (not shown in figure) in the pillion footrest tube (510) so as to redirect the air directly towards the connecting tube (530) instead of the air circulating completely inside the pillion footrest tube (510).
[00060] In yet another embodiment, the present subject matter enables providing cooling through circulation of fresh air to the transmission system (145) along with an air intake structure that includes an air cleaner which helps in cooling of the transmission system (145) through air-suction mechanism or with the help of cooling fans. Moreover, the transmission system (145) may be further cooled with the help of liquid coolants along with the present subject matter.
[00061] Fig. 8 illustrates an enlarged perspective view of a hugging provision 520 wherein one portion of the hugging provision is a pillion footrest tube hugging provision (810) and the other portion is a side tube hugging provision (820). Such hugging provision aids to further increase the strength of the pair of side tubes (410,420) locally as it provides support to the frame and the pillion footrest tube assembly (210), thereby enhancing rigidity and sturdiness of the pair of side tubes (410,420), hence increasing the stiffness and durability of the entire frame assembly.
[00062] Fig.9 illustrates a schematic view of the air flow circulation inside the frame assembly (105) directing air to the CVT cover (220) or to the transmission assembly (145), according to an embodiment of the present subject matter. The fresh air present inside the vehicle flows through the opening (540) in one of the side tubes (410), passing through the reinforcement structure (520) towards the pillion footrest tube (530) and subsequently reaches to the CVT cover (220) through the connecting tube (510) and the bellow (303) connected through the attaching means (305). Herein, the fresh air which is drawn and flows inside the frame assembly (105) is channeled to the CVT cover (220) through a longer path which results into a dust-free air entering inside the CVT cover (220). Since, the fresh air is travelling a longer path, the amount of dust reduces for every millimeter that the fresh air travels.
[00063] Moreover, the present subject matter further eliminates the need of any suction mechanism to suck the air inside and pass it to the CVT cover (220) and provides for entry of fresh air inside the CVT cover (220) even when the two-wheeled vehicle (100) is driven with a minimum velocity. In an embodiment, due to rotation of the driving pulley, the driven pulley and the belt that rests between them, a centrifugal force (910) is created in the transmission assembly (145) at an opening of the CVT cover (220) which is connected to the bellow (303) that naturally sucks the fresh air from the atmosphere present in and around the vehicle body inside the transmission assembly (145) through one of the pair of side tubes (410). Inside the transmission assembly (145) having the CVT cover (220), the shape of the transmission assembly (145) guides the air around the belt and sheaves to cool such rotating parts. The fresh air runs through the CVT cover (220) and is blown out through a rear opening (not shown) from the transmission assembly (145).
[00064] Further, according to an embodiment of the present subject matter, the pillion footrest tube (530) is manufactured in such a way that the diameter of the pillion footrest tube (530) is bigger, thereby reducing the thickness, thus enabling more amount of fresh air to be channeled inside the frame assembly as bigger the diameter, more the amount of air that could be channeled inside the frame assembly (105). Further, since the thickness of the pillion footrest tube (530) has been reduced as compared to conventional footrest tubes, hence the overall weight of the frame assembly (105) has also been reduced.
[00065] Thus, the present subject matter enables a frame assembly (105) carved out with an angular cut opening cross section instead of a circular cross section that helps in increasing the service life of the frame assembly (105) and the CVT cover (220) by providing a bigger diameter to the pillion footrest tube (530), thus enabling more amount of fresh air inside the CVT cover (220), which further helps in efficient cooling of the CVT systems while providing sufficient stiffness and durability to the frame assembly (105) to withstand the payload and rear axle loads.
[00066] While certain features of the claimed subject matter have been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those skilled in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the claimed subject matter.


List of reference signs:
100 vehicle
101 first wheel
102 second wheel
105 frame assembly
106 head tube
107 main tube
110 rear tubes
131 front suspension system
134 rear suspension system
135 powertrain
140 engine
145 transmission assembly
150 handle bar assembly
151 step-through portion
155 seat assembly
165 front fender
170A, 170B, 170C plurality of panels
175 rear fender
210 pillion footrest assembly
220 CVT cover
301 clip
303 bellow
305 attaching means
410, 420 pair of side tubes
430 cross tube
440 toggle link bracket
510 connecting tube
520 reinforcement structure
530 pillion footrest tube
540 angular cut opening
610 overlapped reinforcement
810 pillion footrest tube hugging provision
820 side tube hugging provision
910 centrifugal force