DESC:TECHNICAL FIELD
[0001] The present subject matter relates generally to a transmission system for a saddle type two-wheeled or three wheeled vehicle, and more particularly to a transmission cover assembly for said vehicle.
BACKGROUND
[0002] Generally, in a two-wheeled vehicle a body frame extends rearward from a head tube. The body frame acts as a skeleton for the vehicle that supports the vehicle loads. A front portion of the body frame connects a front wheel through one or more front suspension(s). Further, the body frame extends towards a rear portion of the vehicle. A rear wheel is connected to a frame assembly through one or more rear suspension(s). A power train like internal combustion engine or a traction motor or a combination is mounted to the frame assembly of the vehicle. The engine assembly is functionally connected to the rear wheel, which provides the forward motion to the vehicle. Typically, plurality of panels is mounted to the frame assembly of the vehicle that covers various vehicle parts mounted thereon.
[0003] Typically, the internal combustion engine is functionally coupled to a rear wheel of the vehicle. Furthermore, the vehicle is provided with a transmission system which connects the internal combustion engine and the rear wheel. The transmission system for the vehicle can either be chain driven or belt driven. The transmission system of the vehicle is continuously driven and transfers power from the engine to the rear wheel. Thus, the transmission system operates at a very high temperature and needs a constant cooling mechanism.
[0004] Hence, the present subject matter aims to provide a cooling mechanism for the transmission system of the two-wheeled vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The detailed description of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.
[0006] Fig. 1 illustrates a left side view of an exemplary two-wheeled saddle ride-type vehicle, in accordance with an embodiment of the present subject matter.
[0007] Fig. 2 illustrates a side view of a lower portion of the exemplary two-wheeled vehicle as shown in Fig. 1, in accordance with an embodiment of the present subject matter.
[0008] Fig. 3 illustrates an exploded view of a transmission system in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION
[0009] Typically, a two-wheeled vehicle is provided with an internal combustion engine to provide the vehicle with the required power. The two-wheeled vehicle comprises of a frame assembly to provide a support to the vehicle and act as a skeleton. The vehicle body (external fiber/metallic body) and parts are mounted onto the frame structure. Generally, the internal combustion engine is also mounted onto the frame structure.
[00010] Generally, the internal combustion engine comprises of a cylinder bore and a cylinder head. The combustion process occurs in the cylinder head which results in a to-and-fro motion of a piston accommodated in the cylinder bore. The to-and-fro motion of the piston is sent and converted into a rotational motion of a crankshaft which drives the vehicle. Moreover, the power generated by the internal combustion engine is transferred to the rear wheel of the vehicle. A transmission system is provided which transfers the power from the engine to the rear wheel. However, the transmission system continuously works at a high temperature and needs a constant cooling mechanism.
[00011] In order to achieve such purpose some of the known arts implement an external source of cooling systems being mounted on the vehicle. Such a system makes the vehicle heavy and bulky. In addition to it, it increases the complexity and serviceability issues. Furthermore, such inclusion of external mechanisms for cooling makes the transmission system heavy and complex which results in its constant failures. If constant lubing is not done it leads to generation of friction which then results in wear and tear of the transmission system. The heat generated from engine in cooperation with the generated frictional heat may further promote overheating of the transmission system which can result in a shortened life of the transmission system. Thus, the present subject matter is aimed at providing a low weight, cost effective, easy to manufacture, assemble & service type cooling mechanism for the transmission system. Moreover, decreasing the weight of the vehicle increases the power to weight ratio of the vehicle as well as increases the fuel economy of the vehicle. As per the present subject matter, the cooling mechanism is simple, light and easy to manufacture with less cost. It enhances the serviceability and maintenance of the vehicle as well.
[00012] In an embodiment, the vehicle is provided with a frame structure comprising of head tube disposed in a front portion of the vehicle. The frame structure comprises of a down tube connected to the head tube, extending in a downward and rearward fashion. In addition to it, the frame structure comprises of a main tube extending from the head tube in a straight and rearward fashion. A rear sub frame assembly is provided which is partially connected to the main tube and down tube. The internal combustion engine is functionally connected to the rear wheel through a transmission system. A transmission cover assembly is provided to cover said transmission system. In an embodiment, the transmission cover assembly comprises of openings formed at regular intervals. The rear sub frame assembly is configured with a predetermined profile to direct the atmospheric air in an inward and downward fashion towards the transmission cover assembly. The transmission cover assembly comprises of openings through which the atmospheric air enters and helps in cooling of the transmission system. Hence, the present subject matter also aims to provide a transmission system which is equipped with a guided cooling mechanism adapted to direct the path of the ambient air circulation within the transmission cover assembly so as to cause effective conduction of the heat generated due to friction and stress in the transmission system, and therefore achieves a high degree of heat radiation to the outside and consequently a longer effective life of the transmission system as well as a higher power transmission efficiency as compared with a conventional system. Thus, through such a cooling system the transmission system is effectively cooled without any requirement of any extra parts or element.
[00013] Arrows provided in the top right corner of each figure depicts direction with respect to the vehicle, wherein an arrow F denotes front direction, an arrow R indicates rear direction, an arrow Up denotes upward direction, and an arrow Dw denotes downward direction.
[00014] Fig. 1 illustrates a left side view of an exemplary motor vehicle (100), in accordance with an embodiment of the present subject matter. The said vehicle (100) includes a frame assembly (105) that extends from a head tube (105A), which is disposed in the front portion of said vehicle (100), towards a rear portion of said vehicle (100). Further, said frame assembly (105) extends in longitudinal direction F-R of said vehicle (100). Furthermore, said frame assembly (105) may further comprise a sub-frame formed by a pair of rear tubes (not shown) that extend obliquely rearward from the main frame. An engine assembly (110) is fixedly mounted to said frame assembly (105).
[00015] Moreover, a front portion of a swing arm (115) is swingably connected to said frame assembly (105) and a rear portion of said swing arm (115) rotatably supports a rear wheel (120). Further, said rear wheel (120) is functionally coupled to said engine assembly (110) through a transmission system (205). Said transmission system (205) includes a drive mechanism, a variable gear ratio system, or an automatic type transmission. In one of the embodiment of the present subject matter said transmission system (205) may include a belt drive mechanism. In another embodiments of the present subject matter said transmission system (205) may include a chain drive mechanism. A rear fender (125) disposed upwardly of said rear wheel (120) covers at least a portion of said rear wheel (120). Further, said swing arm (115) is coupled to said frame assembly (105) through one or more rear suspension(s) (not shown). In the present embodiment, a mono-shock type rear suspension connects said swing arm (115) to said frame assembly (105). Similarly, a pair of front forks (130) supports a front wheel (135) and is steerably supported by a head tube (105A). A handlebar assembly (140) is connected to an upper portion of said pair of front forks (130). Further, a front fender (145) covers at least a portion of said front wheel (135) and said front fender (145) is mounted to said front forks (130).
[00016] A fuel tank assembly (150) is mounted to said frame assembly (105) and is disposed rearwardly of said handlebar assembly (140). A seat assembly (155) including a rider seat is disposed rearwardly of said fuel tank assembly (150) and is supported by said frame assembly (105). Further, said seat assembly (155) may include a pillion seat. Further, a pair of rider foot pegs (165) mounted to said frame assembly (105) of said vehicle (100) that enable in supporting the rider’s foot.
[00017] Further, said engine assembly (110) includes an air-fuel supply system (not shown) that supplies air and fuel to said engine assembly (110). An exhaust pipe (not shown) extends from said engine assembly (110) towards a muffler (not shown) that is disposed adjacently of said rear wheel (120). Plurality of panels (170) covers at least a portion of said frame assembly (105) and one or more vehicle parts.
[00018] Furthermore, said vehicle (100) includes various electrical and electronic systems including a starter system (not shown), a headlamp (175), a vehicle control unit, and a tail lamp (180). In addition, said vehicle (100) includes safety systems including a synchronous braking system (not shown), and an anti-lock braking system. In furtherance to it, the present subject matter is applicable for a two-wheeled vehicle and three-wheeled vehicle. Hence, the term vehicle has been used interchangeably in the application which comprises of both two-wheeled and three-wheeled vehicle. Another embodiment of present invention involves a vehicle comprising a frame assembly, and engine assembly, at least one front wheel and at least one rear wheel attached steerably with the frame assembly.
[00019] Fig. 2 illustrates a side view of a lower portion of the exemplary two-wheeled vehicle (100) as shown in Fig. 1, in accordance with an embodiment of the present subject matter. In an embodiment, said frame assembly (105) comprises of a down tube (105B) (not shown) extending in a downward and rearward fashion from said head tube (105A) (not shown). In addition to it, said frame assembly (105) also comprises of a main tube (105C) (not shown) extending in a straight rearward direction from said head tube (105A) (not shown). A holder (not shown) connects said main tube (105C) (not shown) and said down tube (105B) (not shown). In an embodiment, a rear sub frame assembly (105D) is partially attached to said down tube (105B) and said main tube (105C). In embodiment, said transmission system (205) is provided which functionally connects said engine assembly (110) and said rear wheel (120) of said vehicle (100). As per the present subject matter, a transmission cover assembly (210) is provided to cover said transmission system (205) of said vehicle (100) wherein said transmission cover assembly (210) comprises of plurality of openings (215) provided on it at regular intervals at a predetermined range of 45 mm to 60 mm. Further, said transmission cover assembly (210) is arranged in a fashion so as to permit an easy assembly procedure without sacrificing the easiness of serviceability. The ease of serviceability further assures a smooth operation of said transmission system (205) for a lengthened period of time as compared to the technology/mechanism adapted in conventional systems. As per an embodiment of the present subject matter, said rear sub frame assembly (105D) is profiled in manner which diverts the atmospheric air in an inward and rearward fashion towards said transmission cover assembly (210). The flow path of atmospheric air in a laminar fashion, especially in a thin layer just adjacent to the surface is illustrated as FF’ in the present figure. The atmospheric air FF’ being diverted enters said transmission system (205) through said plurality of openings (215) provided on said transmission cover assembly (210). Further, said rear sub frame assembly (105D) is profiled to curve and bend inwards which allows the atmospheric air FF’ to be directed along it towards said transmission cover assembly (210). Thus, the atmospheric air FF’ entering said transmission cover assembly (210) helps in cooling of said transmission system (205).
[00020] Fig. 3 illustrates an exploded view of said transmission system (205) in accordance with an embodiment of the present subject matter. In an embodiment, said transmission system (205) is provided to functionally connect said engine assembly (110) and said rear wheel (120). Further, said transmission system (205) is provided with either of a chain drive or a belt drive mechanism. In an embodiment, said transmission system (205) is covered by said transmission cover assembly (210). As per an embodiment of the present subject matter, said transmission cover assembly (210) is provided with said plurality of openings (215) to allow an entry for atmospheric air FF’ for cooling of said transmission system (205). As illustrated in Fig. 2, the ambient air is circulated into said transmission cover assembly (210) through said plurality of openings (215), circulated about to cool said transmission system (205), and passes out through said plurality of openings (215) on said transmission cover assembly (210). As per an aspect of the present invention, at least one or more (3 in the current embodiment) openings (215) are provided on a top portion (210A) of said transmission cover assembly (210) and one or more (3 in current embodiment) on a bottom portion (210B). In one embodiment of the current invention said transmission cover assembly (210) may include said top portion (210A) and said bottom portion (210B). As per another embodiment of the present subject matter said transmission cover assembly (210) includes either said top portion (210A) or said bottom portion (210B). While along with cooling air, there is high possibility of mud, dust, water etc. getting inside the system and getting collected, leading to early failure of the system and low durability. Thus, plurality of openings (215) is specifically disposed partially on the vertical wall of said transmission cover assembly (210) and partially disposed on the lateral wall as can be seen in Fig, 3. This enables the collected foreign contamination like mud & undesirable water to flow out under gravity. Further, said openings (215) in said transmission cover assembly (210) is arranged such that the ambient air travels through said transmission system (205), always in a direction which is most efficient to achieve an enhanced degree of heat radiation from these parts, thereby cooling them appropriately.
[00021] Additionally in an embodiment of the current invention, the cross section of said plurality of openings (215) is in form of trapezoidal shape with longer edge being disposed on the horizontal surface of said transmission cover assembly (210) both at said top portion (210A) & said bottom portion (210B). This enables lower passage size for entry of mud, water etc. & higher passage for exit under gravity. Furthermore, the shape of said openings (215) has a predetermined range of angle from 45 degrees to 55 degrees, which enables effective heat radiation through air flow. Said plurality of openings (215) is disposed at a predetermined pitch P in the range of 45 mm to 65 mm from each other. In one embodiment of the present invention said pitch P varies throughout said transmission cover assembly (210) in said top portion (210A), said bottom portion (210B) and said arc portion (210C). In an additional aspect of the present invention, similar plurality of openings (215), at least one or more, are provided on an arc portion (210C) of said transmission cover assembly (210) towards the driven end i.e. rear wheel end which enables the hot air to escape. In another embodiment of the present invention, said plurality of openings (215) have a width W in the range starting from 50 mm to 70 mm. Further, said width W of said plurality of openings (215) is such that it is parallel to the lateral wall of said top portion (210A) of said transmission cover assembly (210) when located on said top portion (210A). Furthermore, said width W of said plurality of openings (215) is such that it is parallel to the lateral wall of said bottom portion (210 B) of said transmission cover assembly (210) when located on said bottom portion (210B). In one of the embodiments of the present invention, similar plurality of openings (215), have a length L in the range starting from 10 mm to 20 mm where said length L of said plurality of openings (215) is such that it is perpendicular to the lateral wall of said top portion (210A) when located on said top portion (210A). Furthermore, said length L of said plurality of openings (215) is such that it is perpendicular to the lateral wall of said bottom portion (210 B) of said transmission cover assembly (210) when located on said bottom portion (210B). It is to be noted that the area of said openings (215) for the air inlet is substantially equal to the exit opening which ensures effective flow of cooling air to cool the transmission system & deliver good durability. Additionally, the area of said plurality of openings (215) permits easiness in the servicing (e.g. oiling) and maintenance of said transmission system (205) through them. Also, in one of the embodiment of the present invention the length of a line TT’ which is drawn from the center CA of said arc portion (210C) and center CT of ends of said top portion (210A) and said bottom portion (210B) of said transmission cover assembly (210) falls in the range starting from 500 mm to 600 mm, wherein the radius R of said arc portion (210C) falls within a range of 150 mm to 170 mm. This range of length of line TT’ and radius R enables said transmission cover assembly (210) to accommodate said transmission system (205) in a manner isolating it from the outside, so as to avoid any intrusion of dust, mud, water, etc. into said transmission cover assembly (210) for protection of said transmission system (205) and also, to provide sufficient space for said transmission system (205) to function efficiently and smoothly without causing any wear and tear of said transmission cover assembly (210).
[00022] Thus, the present subject matter presents a cooling mechanism for said transmission system (205). Further, said transmission system (205) is covered by said transmission cover assembly (210) comprising of said plurality of openings (215). Said plurality of openings (215) is provided on said transmission cover assembly (210) to allow an entry of atmospheric air FF’ being diverted by said rear sub frame assembly (105D). Thus, the atmospheric air FF’ entering through plurality of openings (215) provided on said transmission cover assembly (210) enable cooling of said transmission system (205).
[00023] It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein. Many modifications and variations of the present subject matter are possible in the light of above disclosure.

List of Reference Signs

100 Saddle type vehicle
105 Frame Assembly
105A Head tube
105B Down tube
105C Main tube
105D Rear sub frame Assembly
110 Engine Assembly
115 Swing arm
120 Rear wheel
125 Rear fender
130 Front forks
135 Front wheel
140 Handlebar Assembly
145 Front Fenders
150 Fuel tank Assembly
155 Seat Assembly
160 Pillion Rider Foot Pegs
165 Rider Foot Pegs
170 Panels
175 Head lamp
180 Tail lamp
205 Transmission System
210 Transmission cover assembly
210A Top portion
210B Bottom Portion
210C Arc portion
215 Openings
,CLAIMS:We Claim:
1. A saddle type vehicle (100) comprising:
an engine assembly (110) to provide required power to said saddle type vehicle (100);
a frame assembly (105) wherein said frame assembly (105) includes a rear sub frame assembly (105D); and
a transmission system (205) including at least one of a chain-drive or belt-drive mechanism to functionally connect said engine assembly (110) and at least one rear wheel (120) wherein said transmission system (205) is covered by a transmission cover assembly (210) comprising of series of openings (215) formed therein along the length of said saddle type vehicle (100).
2. The saddle type vehicle (100) as claimed in claim 1, wherein said rear sub frame assembly (105D) is configured with a predetermined profile to guide the atmospheric air in an inward and downward direction FF’ towards said transmission cover assembly (210).
3. The saddle type vehicle (100) as claimed in claim 1, wherein transmission cover assembly (210) comprises of at least one of top portion (210A), bottom portion (210B) and arc portion (210C).
4. The saddle type vehicle (100) as claimed in claim 1, wherein said transmission cover assembly (210) has a radius R of said arc portion (210C) in a range from 150 mm to 170 mm.
5. The saddle type vehicle (100) as claimed in claim 1, wherein a series of openings (215) are formed at regular intervals on said transmission cover assembly (210).
6. The saddle type vehicle (100) as claimed in claim 1, wherein said series of openings (215) are positioned at regular intervals of pitch P.
7. The saddle type vehicle (100) as claimed in claim 1, wherein said intervals of pitch P falls within a range of 45 mm to 65 mm from each other on said transmission cover assembly (210).
8. The saddle type vehicle (100) as claimed in claim 1, wherein said series of openings (215) has said pitch P varying throughout said transmission cover assembly (210) in said top portion (210A), said bottom portion (210B) and said arc portion (210C).
9. The saddle type vehicle (100) as claimed in claim 1, wherein said transmission cover assembly (210) has at least one of the said series of openings (215) on said arc portion (210C) towards the driven end i.e. rear wheel end of said saddle type vehicle (100).
10. The saddle type vehicle (100) as claimed in claim 1, wherein said series of openings (215) have a predetermined width W in the range of 50 mm to 70 mm.
11. The saddle type vehicle (100) as claimed in claim 1, wherein said width W of said plurality of openings (215) is parallel to the lateral wall of said at least one of said top portion (210A) or bottom portion (210B) of said transmission cover assembly (210) when positioned on said top portion (210A) or said bottom portion (210B).
12. The saddle type vehicle (100) as claimed in claim 1, wherein said series of openings (215), have a length L in the range starting from 10 mm to 20 mm.
13. The saddle type vehicle (100) as claimed in claim 12, wherein said length L of said plurality of openings (215) is perpendicular to the lateral wall of said top portion (210A) when positioned on said top portion (210A).
14. The saddle type vehicle (100) as claimed in claim 12, wherein said length L of said plurality of openings (215) is perpendicular to the lateral wall of said bottom portion (210 B) of said transmission cover assembly (210) when positioned on said bottom portion (210B).
15. The saddle type vehicle (100) as claimed in claim 1, wherein shape of said series of openings (215) has a groove with a predetermined range of angle from 45 degrees to 55 degrees.
16. The saddle type vehicle (100) as claimed in claim 1, wherein the area of said openings (215) for the air inlet is substantially equal to the area of said openings (215) for the air outlet.
17. The saddle type vehicle (100) as claimed in claim 1, wherein the length of a line TT’ drawn from the center CA of said arc portion (210C) and center CT of ends of said top portion (210A) and said bottom portion (210B) of said transmission cover assembly (210) falls in the range starting from 500 mm to 600 mm.