DESC:Technical Field
[1] The present subject matter described herein generally relates to a body frame for a two-wheeled vehicle and particularly relates to construction of a main frame member of said body frame for accommodating a steering assembly of said two-wheeled vehicle.

Background
[2] Conventionally, two-wheeled vehicles make use of metal tubes or tubes composed of metal alloys such as steel for forming a body frame thereof. Said tubes typically form a closed framework to interconnect various parts such as body covers, seat, engine etc. Besides, said tubes act as load bearing members which serve to take the impact while riding on bad roads in full load conditions.
[3] However, conventional body frames are prone to having weak joints, said joints acting as points of stress. Especially, points of stress are developed between a head tube and a main tube of the body frame. As a result, typically a joint between said head tube and the main tube is reinforced by providing additional gussets. However, providing additional gussets leads to an increase in the number of parts, thereby leading to an overall increase in weight of the two-wheeled vehicles.
[4] In light of the above circumstances, there is a need to provide lighter frames with optimised load and weight distribution. Vehicle body frames are being increasingly replaced by light weight body frames made of composite materials such as fibre reinforced resin. Particularly, in light weight body frames it is important to optimise load and weight distribution since certain parts of the body frame are subject to greater stress and load and it is necessary to reinforce such parts. Moreover, in two-wheeled vehicles having a body frame made of light weight material such as fibre reinforced resin, there is a need to provide structural members which serve to receive or guide components of the vehicle such as the front fork. Typically, since the steering assembly including a front fork is composed of hard material such as steel tubes and the like, care must be taken while assembling said front fork into a head tube of said body frame to ensure that there is no damage to the resin fibres of said head tube. Further, there is also a need to provide steering bearings for reducing friction around the front fork, without causing fatigue damage to said head tube. Moreover, the head tube must also be able to withstand compression load due to tightening torque exerted while securing the steering assembly to the head tube.
[5] There is therefore a need to ensure proper accommodation of the steering assembly including the front fork and the bearings in a body frame of a two-wheeled vehicle made of light weight material such as fibre reinforced resin without involving damage to portions of said body frame.

Summary of the Invention
[6] The present invention has been made in view of the above circumstances.
[7] It is an object of the present invention to provide a body frame including a main frame member for a two-wheeled vehicle, said body frame being light in weight, yet whose strength is uncompromised.
[8] It is yet another object of the present invention to provide a body frame including a main frame member made of composite material such as fibre reinforced resin.
[9] It is another object of the present invention to provide a body frame including a main frame member which is adapted to receive a steering assembly including a front fork without involving damage to a constituent material of said main frame member.
[10] It is yet another object of the present invention to provide a body frame including a main frame member which integrally includes a bent first portion adapted to function as a head tube of the body frame.
[11] With the above and other objects in view, the present invention provides a two-wheeled vehicle including a body frame made of composite material such as fibre reinforced resin. The body frame extending from a front to a rear portion of said vehicle includes a main frame member extending rearwards from a foremost end of said body frame, a pair of side frames connected to a side portion of said main frame and extending rearwards towards a rear side of said vehicle. Particularly, the main frame member includes a bent first portion and an extended second portion. Particularly, while the bent front portion serves to function as a head tube, the extended second portion serves to function as the main tube.
[12] As per the present invention, the bent first portion of the main frame is adapted to receive a steering assembly including a front fork of the two-wheeled vehicle. As per an aspect of the present invention, the bent first portion is enmoulded with an insert member which extends from a top section of said bent first portion up to a section below the bent first portion. In other words, while a substantial portion of the insert member is contained within the bent first portion of the main frame member, a portion of the insert member extends outside the bent first portion of the main frame member. Different layouts are chosen for enmoulding said insert member to the bent first portion of the main frame. The construction of the main frame as per the present disclosure allows the front fork to be inserted into the insert member enmoulded with the bent first portion of the main frame member. As per an aspect of the invention, the insert member is composed of a rigid material such as steel. Presence of the insert member enmoulded with the bent first portion of the main frame member enables convenient insertion of the front fork into the main frame member without involving any damage to said main frame member composed of fibre reinforced resin. Thus, the insert member serves as a guide for the front fork of the two-wheeled vehicle. Moreover, since the insert member is made of steel, assembly of a pair of steering bearings for the lubrication of the front fork into said insert member is conveniently facilitated. Further, the present construction of the main frame member also aids in ensuring that no damage occurs thereto since the pair of steering bearings are not directly inserted into the bent first portion of the main frame member.
[13] Summary provided above explains the basic features of the invention and does not limit the scope of the invention. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings.

Brief Description of Drawings
[14] The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description and accompanying drawings where:
[15] FIG.1 illustrates a side view of a two-wheeled vehicle in accordance with an embodiment of the present invention.
[16] FIG.2 illustrates a perspective view of a body frame of said two-wheeled vehicle in accordance with an embodiment of the present invention.
[17] FIG.3 illustrates a detailed view of a main frame member of said body frame in accordance with an embodiment of the present invention.
[18] FIG.3a illustrates a cross sectional view showing details of said main frame member in accordance with an embodiment of the present invention.
[19] FIG.4 illustrates a sectional view of an extended second portion of the main frame member taken along a line A-A’ shown in FIG.3 in accordance with an embodiment of the present invention.
[20] FIG.5a illustrates a sectional view of a bent first portion of the main frame member taken along a line B-B’ shown in FIG.3 in accordance with a first embodiment of the present invention.
[21] FIG.5b illustrates a sectional view of the bent first portion of the main frame member in accordance with a second embodiment of the present invention.
[22] FIG.5c illustrates a sectional view of the bent first portion of the main frame member in accordance with a third embodiment of the present invention.
[23] FIG.5d illustrates a sectional view of the bent first portion of the main frame member in accordance with a fourth embodiment of the present invention.
[24] FIG.6 illustrates a main frame member for a body frame of a two-wheeled vehicle having a step over frame structure.
[25] FIG.7 illustrates a perspective view of the main frame member as per another embodiment of the present invention.

Detailed Description
[26] Exemplary embodiments detailing features of the body frame including a main frame member thereof, in accordance with the present invention will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present invention will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Further, it is to be noted that terms “upper”, “lower”, “right”, “left”, “front”, “forward”, “rearward”, “downward”, “upward”, “top”, “bottom” and like terms are used herein based on the illustrated state or in a standing state of a two-wheeled vehicle with a driver riding thereon unless otherwise elaborated. Furthermore, a longitudinal axis refers to a front to rear axis relative to said vehicle, while a lateral axis refers to a side to side, or left to right axis relative to the two-wheeled vehicle.
[27] Firstly a description is made of an entire schematic structure of a two-wheeled vehicle 10, with reference to FIG.1.
[28] FIG.1 is a side view of the vehicle (10). The invention disclosed herein has been exemplified for a two wheeled vehicle such as a scooter type motorcycle. As shown in FIG.1, said vehicle (10) includes a body frame (11) (shown in FIG.2), for example an underbone body frame, made of a composite material such as fibre reinforced resin. For example, the material chosen for the fibre may be either glass fibre or carbon fibre and the like.
[29] Said body frame (11) which forms a skeleton of the vehicle (10), is covered by different body covers. A front cover (1) is provided to cover a forward facing side of the body frame (11) and is disposed above a front fender (2). A headlamp cover (3) is disposed above the front cover (1) to encompass a headlamp (not shown) and a handle bar (5) at least partially.
[30] Further, a leg shield (6) is disposed on a rear side of the front cover (1), which serves to protect a rider’s legs from running wind. From a front lower portion of the leg shield (6), a floorboard (7) extends in a vehicle longitudinal direction towards a central cover member (4) of the vehicle (10).
[31] Left and right side covers (8) are disposed to cover left and right side surfaces of a rear portion of the body frame (11).
[32] A seat (20) is disposed above the left and right side covers (8). A fuel tank (not shown) is arranged in the rear portion of the body frame (11) with its sides covered by the left and right side covers (8). Further, a utility box (not shown) supported between a pair of side frame members (13) (shown in FIG.2) of the body frame (11), is disposed in front of the fuel tank and above a power unit (22). The vehicle 10 is powered by the power unit (22) including at least one of an internal combustion engine or a traction motor. Power from the power unit (22) is transmitted through a transmission system to a rear wheel (35). The transmission system may include a fixed gear chain drive or continuously variable transmission (CVT) or an automatic manual transmission (AMT) or the like.
[33] The internal combustion engine of the power unit (22) is supplied with an air fuel mixture sent in by a throttle body (not shown) to a combustion chamber thereof. In the present embodiment the throttle body is a carburettor. However, in another embodiment, the throttle body can be an electronic fuel injection device.
[34] Further, combustion gases generated by the engine are let out as exhaust from a muffler (not shown).
[35] A toggle link (17) (shown in FIG.2) is supported swingably between a rear portion of the pair of side frame members (13). The rear wheel (35) is connected to the toggle link (17) via the power unit (22), said power unit (22) being an internal combustion engine.
[36] Further, the vehicle (10) comprises a power source (not shown) that may include a battery or a fuel cell or the like. For example, the power source may be used for propulsion of the vehicle and for powering lighting systems or other electrical and electronic parts of the vehicle such as a vehicle control unit, an anti-lock braking system or a synchronous braking system.
[37] Furthermore, said vehicle 10 also includes various electronic and electrical systems such as a vehicle control unit, an anti-lock braking system, or a synchronous braking system.
[38] FIG.2 perspective view of the body frame (11) of said vehicle (10) in accordance with an embodiment of the present invention.
[39] As may be seen in FIG.2, the body frame (11) includes a main frame member (12) extending rearwardly and downwardly from a foremost end of said body frame (11) up to a floorboard portion of said body frame (11). The body frame (11) further includes the pair of side frame members (13) connected to the main frame member (12) and extending rearwardly and inclinedly upwardly up to a rear end of said two wheeled vehicle (10). In the present embodiment, the pair of side frame members (13) is connected to said main frame member (12) by means of a pair of floorboard panels (14). Thus, in the present embodiment, the floorboard portion of the body frame (11) is defined by at least a portion of the main frame member (12) being encompassed between the pair of floorboard panels (14) in a vehicle longitudinal direction, and between a portion of the pair of side frame members (13) in a vehicle lateral direction. In the present embodiment, the body frame (11) including the main frame member (12), the pair of side frame members (13), and the pair of floorboard panels (14) is made of light weight material such as fibre reinforced resin or polymeric material such as plastic. Owing to the use of light weight material, substantial reduction in overall weight of the body frame (11) is achieved. However, use of appropriate support structures at the joints renders sufficient strength for the body frame (11). Moreover, use of light weight material also aids in lowering NVH transmission through the body frame (11) to a rider.
[40] As per an aspect of the present invention and as may be seen in FIG.3, the main frame member (12) is an integrated member which serves to receive a steering assembly including a front fork (40) of said two-wheeled vehicle (10). In other words, the main frame member (12) also serves to function as a head tube of the two-wheeled vehicle in order to support the front fork (40). Particularly, the main frame member (12) includes a bent first portion (12a), and an extended second portion (12b). While the bent first portion (12a) constitutes a foremost portion of the main frame member (12), the extended second portion (12b) extending rearwardly and inclinedly downwardly from the bent first portion (12a) towards the pair of floorboard panels (14); constitutes a latter portion/terminating portion of the main frame member (12). In the present embodiment and as per an aspect of the present invention, the bent first portion (12a) of the main frame member (12) is enmoulded with an insert member (12aa). In the present embodiment, the insert member (12aa) is made of a material different from that of the main frame member (12). Preferably, the insert member (12aa) is made of steel. Further, preferably the insert member (12aa) is disposed centrally in the bent first portion (12a) of the main frame member (12). In the present embodiment, the insert member (12aa) extends from a top section (12at) of the bent first portion (12a), up to a bottom section (12al) below and outside said bent first portion (12a). Presence of the insert member (12aa) in the main frame member (12) ensures that the front fork (40) can be easily guided into the bent first portion (12a) of the main frame member (12) without causing damage to fibres constituting said bent first portion (12a). Particularly, the front fork (40) is inserted into said insert member (12aa) through a central shaft (45) thereof. Further, presence of the insert member (12aa) also facilitates the convenient insertion of at least two steering races (50) of the steering assembly including ball bearings (50a) and a bearing cup (50b) typically made of steel or any other alloy. Therefore, it ensured that no damage is caused to the structure of the main frame member (12) during insertion of the steering race (50). The steering race (50) is provided to ensure lubrication of the front fork (40).
[41] As per another embodiment of the present invention and as may be seen in FIG.3a, said insert member (12aa) is press fitted with two or more metal insert elements (12ad) for accommodating at least two steering races (50). For example, while at least one metal insert element of said two or more metal insert elements is press fitted in a top portion (12aat) of said insert member (12aa), another metal insert element is press fitted in a bottom portion (12aal) of said insert member (12aa). In the present embodiment, said two or more metal insert members are made of a material different from that of insert member (12aa). For example, while said insert member (12aa) may be made of Aluminium, said two or more metal insert elements (12ad) may be made of stainless steel. Further, in one embodiment, said metal insert element provided in the bottom portion of the insert member (12aa) may be encasted with a stopper member (12as) to enable restricted pivotal motion of a steering shaft about said bent first portion (12a).
[42] With reference to FIG.4-FIG.5d, construction of the main frame member (12) is elaborated. FIG.4 denotes a cross sectional view of the extended second portion (12b) of the main frame member (12) taken along a line A-A’ shown in FIG.3. For example, as seen in FIG.4, the extended second portion (12b) of the main frame member (12) comprises a plurality of first inner layer members (12bi) joined together to form an outer layer member (12bo). A method of manufacturing said plurality of first inner layer members (12bi) involves forming/moulding each inner layer member of the plurality of first inner layer members (12bi) individually, followed by placing said plurality of first inner layer members (12bi) in a required pattern and pouring a layer of fibre reinforced resin around and between said plurality of first inner layer members (12bi), and moulding them together in order to obtain a solid structure. In other words, the outer layer (12bo) of the fibre reinforced resin holds said plurality of first inner layer members (12bi) in place. Particularly, each first inner layer member of the plurality of first inner layer members (12bi) comprises a first core (12bc) each which is filled with a foam material at the time of moulding. Further, each first inner layer member is formed by pouring fibre reinforced resin around the foam material. The foam material may or may not be retained in the main frame member (12) based on manufacturing requirements. Whereas in one embodiment, said first core of each first inner layer member (12bi) includes the foam material, in another embodiment, each first core of each first inner layer member (12bi) does not include foam material. In the present embodiment, and as may be seen in FIG.4, the main frame member (12) in the extended second portion (12b) has a first cross section (A-A’) which is square shaped. However, the first cross section (A-A’) of the extended second portion (12b) of the main frame member (12) may be varied based on requirements by altering the shape of each first inner layer member or that of a mould holding said plurality of first inner layer members together. In the present embodiment, the first cross section (A-A’) of the main frame member (12) is maintained throughout the length of the extended second portion (12b).
[43] In the present embodiment and as per an aspect of the present invention, the main frame member (12), in the bent first portion (12a) is formed having a second cross section (B-B’) which is non identical to that of the first cross section (A-A’) in order to accommodate the insert member (12aa). A method of enmoulding the insert member (12aa) along with the bent first portion (12a) of the main frame member (12), involves placing the insert member (12aa) surrounded at least partially by a plurality of second inner layer members (12ai) in a mould, followed by pouring fibre reinforced resin around and between said insert member (12aa) and the plurality of second inner layer members (12ai), and baking or moulding them together.
[44] FIG.5a-FIG.5d denotes the various layouts that may be obtained while enmoulding the insert member (12aa) with the bent first portion (12a) of the main frame member (12). For example as per a first embodiment of the present invention, and as may be seen in FIG.5a, the second cross section (B-B’) is obtained by placing the insert member (12aa) centrally, surrounded by the plurality of second inner layer members (12ai) from all sides, followed by pouring fibre reinforced resin around said plurality of second inner layer members (12ai) surrounding the insert member (12aa) and between said plurality of second inner layer members (12ai) and the insert member (12aa). Subsequent to pouring of the fibre reinforced resin, baking or moulding is performed to obtain a solid structure.
[45] Similar to the extended second portion, each second inner layer member includes a second core (12ac); and each of said second core (12ac) may or may not include the foam material. Further, each second inner layer member of the plurality of second inner layer members (12ai) is obtained by moulding in a manner such that at least geometry/shape of an inner periphery (12aip) thereof conforms to a geometry/shape of at least a portion of outer periphery of the insert member (12aa), so that the inset member (12aa) is accurately enmoulded when each of the second inner layer member of the plurality of second inner layer members (12ai) is placed surrounding the insert member (12aa) and the fibre reinforced resin is poured around the same. Moreover, based on the shape of the mould, the geometry/shape of an outer periphery X of said plurality of second inner layer members (12ai) in the second cross section (B-B’) may vary. Preferably, the geometry of at least two faces of said outer periphery X is either hemispherical or orthogonal.
[46] For example, FIG.5a denotes the second cross section (B-B’) as per a first embodiment, obtained by placing the insert member (12aa) centrally surrounded by the plurality of second inner layer members (12ai). In the present embodiment, the outer periphery X includes at least two faces having a hemispherical geometry and at least two faces having an orthogonal geometry. FIG.5b denotes the second cross section (B-B’) as per a second embodiment of the present invention and includes the outer periphery X having a square geometry. FIG.5c denotes the second cross section (B-B’) as per a third embodiment of the present invention and includes the outer periphery X having a circular geometry. FIG.5d denotes the second cross section (B-B’) as per a fourth embodiment of the present invention. In the second cross section (B-B’) as per the fourth embodiment, the insert member (12aa) is placed off set with respect to the multiple inner layer members (12ai), unlike the first three embodiments where the insert member (12aa) is placed centrally with respect to the plurality of second inner layer members (12ai). Further, the outer periphery X as per the fourth embodiment includes at least two faces forming an orthogonal geometry. As may be seen in FIG.5d a gusset member (12g) to externally support said insert member (12aa) to the bent first portion (12a) of the main frame member (12a) is provided. The second cross section (B-B’) extends throughout length of the bent first portion (12a).
[47] The bent first portion (12a) having the second cross section (B-B’) as described above is allowed to blend with the extended second portion (12b) having the first cross section (A-A’), thus resulting in the formation of the main frame member (12) having an integrated structure made of fibre reinforced resin. Presence of the insert member (12aa) ensures that no impairment/damage occurs to fibres in the main frame member (12) while the front fork is assembled, as the insert member (12aa) serves to guide the front fork during assembly. Moreover, since the insert member (12aa) is enmoulded along with the main frame member (12), no additional parts are required to support the insert member (12aa), thereby easing assembly operations.
[48] FIG.6 denotes the use of the main frame member (12) including the bent first portion (12a), and the extended second portion (12b) as per the present invention for a step over type body frame for use in motorcycles; constituting another embodiment of the present invention. Further, the bent first portion (12a) is enmoulded with the insert member (12aa) for receiving the front fork.
[49] The main frame member (12) may also have a split upper portion (12c), said split upper portion (12c) being adapted to receive the insert member (12aa) as per an embodiment of the present invention and as may be seen in FIG.7.
[50] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention.
,CLAIMS:We claim:
1. A two-wheeled vehicle (10) comprising:
a body frame (11) operable to support components of the two-wheeled vehicle (10), said body frame (11) comprising a main frame member (12), a pair of side frame members (13) and a pair of floorboard panels (14); and
a steering assembly, said steering assembly including a front fork (40) of said two-wheeled vehicle (10);
wherein the main frame member (12) integrally includes a bent first portion (12a)and an extended second portion (12b), wherein the bent first portion (12a)of the main frame member (12) is enmoulded with an insert member (12aa), said insert member (12aa)being adapted to receive the steering assembly of the two-wheeled vehicle.
2. The two-wheeled vehicle (10) as claimed in claim 1, wherein the bent first portion (12a) is disposed on the foremost end of the body frame (11), and wherein the extended second portion (12b) extends rearwardly and downwardly from said bent first portion(12a) upto said pair of floorboard panels (14), and wherein the material of the mainframe member (12) is one of fibre-reinforced resin and polymer.

3. The two-wheeled vehicle (10) as claimed in claim 1, wherein the insert member (12aa) made of a rigid material is centrally disposed in said bent first portion (12a), the insert member (12aa) having a length extending from a top section (12at) of the bent first portion (12a) and beyond a bottom section (12al) of said bent first portion(12a).

4. The two-wheeled vehicle (10) as claimed in claim 1, wherein said insert member (12aa)is press fitted with at least two insert elements (12ad), at least one each being fitted in a bottom portion (12aat) and top portion (12aal) respectively of said insert member(12aa), said insert elements (12ad) adapted to accommodate at least two steering races(50).

5. The two-wheeled vehicle (10) as claimed in claim 4, wherein one of said insert element (12ad) disposed in a bottom portion (12aat) of said insert member (12aa) is encasted with a steering stopper member (12as).

6. The two-wheeled vehicle (10) as claimed in claim 1, wherein the extended second portion (12b)of the main frame member (12) comprises a first cross-section (A-A’) defined by a plurality of first inner layer members (12bi), said plurality of first inner layer members (12bi) being joined together to form an outer layer member (12bo).

7. The two-wheeled vehicle (10) as claimed in claim 6, wherein each first inner layer member of the plurality of first inner layer members (12bi) is individually moulded to have a pre-determined pattern and comprise a first core (12bc) each, and wherein said outer layer member (12bo) is formed by pouring fibre reinforced resin interstitial the plurality of first inner layer members (12bi) and around said plurality of first inner layer members (12bi).

8. The two-wheeled vehicle (10) as claimed in claim 7, wherein each first core (12bc) includes a foam material.

9. The two-wheeled vehicle (10) as claimed in claim 1, wherein said bent first portion (12a) comprises a second cross section (B-B’) defined by a plurality of second inner layers (12ai) at least partially surrounding said insert member (12aa).

10. The two-wheeled vehicle (10) as claimed in claim 9, wherein said second cross section (B-B’) is obtained by placing said insert member (12aa) surrounded at least partially by said plurality of second inner layer members (12ai) in a mould followed by pouring fibre reinforced resin around and interstitial said insert member (12aa) and the plurality of second inner layer members (12ai).