Claims:We Claim:
1. A vehicle (100) having frame includes,
an engine (106); said engine comprises
a crankcase (RH, LH) enclosing transmission assembly; said transmission assembly comprises:
a crankshaft (301),
a driven shaft (302),
a clutch (308), wherein said clutch (308) is installed on the crankshaft (301),
an oil pump cover (403), said oil pump cover (403) configured to have at least one extended boss (602),
a retainer (310), said retainer (310) configured to have side walls (603),
a housing (203) covering crankcase LH (204L),
wherein retainer (310) disposed between housing (203) and oil pump cover (403) such that said retainer (310) makes a predetermined angle ?A at the center of the clutch (308) when disposed at bottom half of the clutch (308).

2. The vehicle (100) having frame as claimed in claim 1, wherein said predetermined angle ?A ranges less than 180 degree at the center of the clutch (308) when disposed at bottom half of the clutch (308).

3. The vehicle (100) having frame as claimed in claim 1, wherein said retainer (310) is configured to have
a plurality of spaced apart yokes (604) along at least one side of the retainer (310) facing oil pump cover (403);
said yokes (604) configured to have a plurality of apertures for receiving respective mounting means to removably mount the retainer (310) on the extended boss (602) of the oil pump cover (403).

4. The vehicle (100) having frame as claimed in claim 1, wherein said retainer (310) is formed with an arcuate or concave shape.

5. The vehicle (100) having frame as claimed in claim 1, wherein said retainer (310) is mounted on at least one of the extended boss (602) of the oil pump cover (403) by suitable mounting means.

6. The vehicle (100) having frame as claimed in claim 1, wherein at least one extended boss (602) holds the retainer (310), said another boss (602) act as stopper to resist the rotational movement of the retainer (310).

7. The vehicle (100) having frame as claimed in claim 1, wherein said retainer (310) configured to have at least two yokes (604), said yokes (604) having mounting holes.

8. A vehicle (100) configured to have a frame comprising:
an engine (106);
a crankcase (RH, LH) enclosing transmission assembly (TA); said transmission assembly (TA) comprises:
a crankshaft (301),
a driven shaft (302),
a clutch (308), wherein said clutch is installed on the crankshaft (301),
an oil pump cover (403),
a housing (701), said housing (701) provided with retainer (703), wherein said retainer (703) configured to have two diverging edges (703A, 703B) joined to form a neck (703C) when moved from the bottom to top of the housing (701) to circumferentially cover the clutch (308).
9. The vehicle (100) as claimed in claim 7, wherein said retainer (310) configured to have an inner surface, said inner surface of the retainer (310) adapted to have at least 2 milli meter gap from the clutch (308). , Description:TECHNICAL FIELD
[0001] The present subject matter relates to transmission assembly. More particularly, the present subject matter relates to power train lubrication.
BACKGROUND
[0002] Conventionally, the saddle type vehicles are powered by an internal combustion (IC) engine. An internal combustion (IC) engine comprises a cylinder head, abutting a cylinder block to form a combustion chamber where the burning of air fuel mixture occurs. The forces generated due to combustion of air fuel mixture is transferred to a piston which is capable of reciprocating inside the cylinder block, and this reciprocating motion is transferred to rotary motion of the crankshaft through a connecting rod by the slider crank mechanism. Many saddle type two and three wheeled vehicles such as mopeds, scooters and other automobiles operate on single stage transmission system, wherein a crankshaft of the IC engine is connected to a wheel of the two wheeled vehicle through single stage reduction gear train. Additionally, IC engines can be with at least one cylinder.
[0003] As in automobiles, torque and speed are important parameters, these can vary as per different segment of the vehicle; likewise, the saddle type wheelers are designed by keeping these two parameters in mind. It is always a challenge for the automobile manufactures to have appropriate balance between both torque and speed, so in order to achieve different speed at varying loads similarly different torque at different loads requires transmission system or gearbox. Power generated from the power unit when transmitted directly to rear wheel will lead to inappropriate torque because direct drive results in uncontrolled speed or sub-optimal speed and operating conditions to achieve best engine performance i.e. torque and rpm (revolutions per minute), Therefore, for best vehicle performance and optimal operating conditions, to transmit power from the power unit to rear wheel of the vehicle a transmission or gear box is typically provided. However, a trade-off between torque requirement and fuel economy is difficult in a single speed power train since at higher torque requirements the fuel economy drops. The critical issues involved in the design of the transmission system are improving efficiency, better operability and reduce transmission losses and at the same time retain its attractive features of low cost and easy drivability. The gear box provides various kind of gear ratio as per user requirement. The gearbox is like a machine having controlled application, various gears of different sizes, shafts etc. The gear box has a multiple gear ratio with ability to switch between various speeds. There are many modes of switching like manually or automatically. Automatic transmission system and manual transmission system implemented in such two or three wheeled saddle vehicles such as scooters are known in art. Introducing automatic transmission systems in compact layout and small sized vehicles is difficult in view of the adverse impacts viz. size, layout, cost, weight, number of parts to accommodate the additional transmission components such as clutch, gear trains and one-way clutches. Such systems are more viable for a four wheeled vehicle owing to the feasibility of space & layout as well as the cost. However, for a saddle type two-wheeler or a three-wheeler, there exists a challenge to design a compact, low cost & efficient transmission system with good durability & reliability.
BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0005] Fig. 1A illustrates a left side view of an exemplary vehicle, where typically enlarged power and transmission mechanism having oil accumulated to one side during gradient is shown.
[0006] Fig. 1 illustrates a left side view of an exemplary vehicle, as per first embodiment of the present invention.
[0007] Fig. 2 illustrates a left side view of engine with wheel drive of the vehicle of Fig.1, as per first embodiment of the present invention.
[0008] Fig. 3 illustrates a left side perspective view of the engine where housing is omitted from the Fig. 2 as per first embodiment of the present invention.
[0009] Fig. 4 illustrates an exploded view of the engine and transmission assembly as per first embodiment of the present invention.
[00010] Fig. 5 illustrates a cut section of figure 3 taken along plane A-A’ of the engine and transmission assembly of Fig. 3 as per first embodiment of the present invention.
[00011] Fig. 6a illustrates a left side perspective view of the centrifugal clutch is shown with retainer as per first embodiment of the present invention.
[00012] Fig. 6b illustrates a left side perspective view of the retainer mounted on oil pump cover where other parts are omitted from the Figure as per first embodiment of the present invention.
[00013] Fig. 7 illustrates a partial sectioned top view to show the retainer as per second embodiment of the present invention.
[00014] Fig. 8 illustrates a perspective view of the housing with the retainer as per second embodiment of the present invention.

DETAILED DESCRIPTION
[00015] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder. According to an embodiment, the prime mover is an internal combustion (IC) engine, said internal combustion (IC) engine described here operates in four cycles. Such an internal combustion (IC) engine is installed in a step through type two or three wheeled vehicle. Also, the prime mover includes the traction motor and various other propelling means generally known in art. Further "front" and "rear", and "left" and "right" referred to in the ensuing description of the illustrated embodiment refer to front and rear, and left and right directions as seen from a rear portion of the two wheeled vehicle and looking forward. Furthermore, a longitudinal axis Y – Y’ unless otherwise mentioned, refers to a front to rear axis relative to the prime mover i.e. engine, while a lateral axis C – C’ unless otherwise mentioned, refers generally to a side to side, or left to right axis relative to the prime mover i.e. engine.
[00016] However, it is contemplated that the disclosure in the present invention may be applied to power train of any vehicle having without defeating the spirit of the present subject matter. The detailed explanation of the constitution of parts other than the present invention which constitutes an essential part has been omitted at suitable places.
[00017] Generally, in a saddle-wheeled vehicle with a step-through type, a step-through space is provided. The step-though space has a floorboard extending either side in the lateral direction C – C’ and may be used for carrying loads or for the rider to rest feet. In such vehicles, the frame structure starts from the head pipe, and extends downwards to the step-through space and again rises to form a driver seat, crosses a pillion seat and finishes at the rear lamp assembly to form a backbone frame structure. The IC engine is horizontally disposed type that is, a cylinder axis (the axis on which the piston of the IC engine reciprocates) is substantially parallel to the central longitudinal axis of the two wheeled vehicle. Typically, the frame assembly acts as a skeleton for the vehicle that supports the vehicle loads.
[00018] A transmission system for such a wheeled vehicle such as scooter type vehicle comprises a single speed transmission system. Such saddle type vehicles have common requirements of low weight, low cost, high efficiency, good controllability throughout the entire speed range. Typically, the transmission system includes a single transmission stage, a centrifugal clutch, and driven shaft having a sprocket at its end, through which the final drive to a rear wheel is connected. A multistage transmission typically adds to the cost of the vehicle making it undesirable for low cost commuting vehicles. The centrifugal clutch ensures that at low to idle speeds the power transmission from the IC engine is disengaged to the rear wheel. The final drive to the rear wheel of the saddle type wheeled vehicle is usually a positive drive such as sprocket and chain arrangement. Typically, in the two or three wheeled saddle vehicle, a kick-start mechanism or the like is used to crank the IC engine. The kick-start mechanism includes various components such as kick-rod, various gear(s), a return spring, and a ratchet arrangement.
[00019] Conventionally, in the two or three wheeled vehicle, there is a problem of low torque at low speeds. For example, when the two wheeled vehicle is climbing a gradient on the road or heavy load is to be pulled so there is requirement of high torque at the rear wheel to pull the vehicle, and the transmission assembly may not be able to provide the same. Further, moving at low speeds with less torque results in loss of fuel economy. Furthermore, at higher speeds, a fixed transmission ratio gives limitation to speeds the vehicle can travel and results in loss of fuel economy. Hence, the transmission assembly may not be able to provide sufficient torque and the internal combustion engine may get switched off. Hence, the design of IC engine known in the art and its related components disposed is critical as it is designed in optimizing the engine layout to make in less bulky, deliver optimal torque to revolution per minute performance and easy to assemble. Implementing transmission assembly in the existing layout involves extensive design and layout changes, which is not only difficult but also cumbersome and difficult to access. Further, a transmission assembly should be implementable with minimal changes in existing layout and minimum modification of frame component supporting the IC engine. Furthermore, there should be standardization of parts wherein single speed and two speeds can be introduced based on customer needs and requirements, different markets or variants as desired by the manufacturer. An automatic or variomatic transmission is the obvious choice as it can enable achieving reasonable mechanical efficiency, fuel consumption, but albeit at a cost penalty. It can accommodate the range of vehicle needs and can operate smoothly. In this regard, the there are many transmission mechanisms known in art.
[00020] Conventional transmission systems such as the automatic transmission systems have drawbacks wherein additional components are introduced causing layout constraints in designing a compact low weight power train as well as vehicle. Such additional components include the introduction of a new transmission stage in the existing single speed IC engine including gear train mechanism and multiple centrifugal clutches making the entire power train bulky and large in size. Such solution requires complete overhaul of the IC engine layout and involves extensive research and development and considerable investment to design a new IC engine with transmission system. The crankshaft of a compact powertrain and compact vehicle can accommodate only selected components, and hence any addition of new components for additional features are difficult. This also increases the cost of the vehicle extensively. Further, for having low weight IC engine, the current layout of IC engine has to been made compact, any changes in IC engine layout adversely affects its space occupied in the two wheeled vehicle and also involves complete redesign of frame assembly to support the IC engine as well as its location/mountings. Hence, there is a need to introduce transmission assembly with least and/or minimum changes in IC engine layout which can operate with single speed ratio and deliver optimal performance with good durability of the powertrain while overcoming all of the problems known in the art.
[00021] Further, the IC engine is functionally connected to a rear wheel of the vehicle such as by a sprocket and chain drive, which provides the forward motion to the vehicle. Further, the tension in the transmission means like belt or chain is a very essential parameter that determines engine performance. The chain transmission is a very important aspect in the effective design of the internal combustion (IC) engine and transmission assembly. Such configuration is primarily used because of higher center distance between crankshaft and driven shaft which results in reduced noise, low vibration operation and efficient working of the IC engine. Silent chain is often used in transmission in shaft drives on four cycle engines. The crankshaft location and number of sprocket teeth are usually decided when the engine is designed, since various factors determine the number of chain pitches and wrap angle and sprocket position. Thus, it is important to have appropriate wrap angle, which ensures proper load transfer between chain and sprocket, so there must be an adequate number of sprocket teeth engaging the chain, at large ratios, the number of teeth engaged on the small sprocket may not be enough. This will not be a problem if the chain drive is designed to provide a minimum wrap angle of 120 degrees, however larger wrap angle on other hand results into more heat generation. Thus, the silent chain life generally depends on lubrication conditions, the major functions of lubrication in the silent chain are to prevent wear by coating the pin and link apertures with an oil film, secondly, to dissipate friction heat that causes galling.
[00022] Moreover, one-way clutch in a single compact unit allows the internal combustion engine to be started by an electric motor and after the electric starter has started the internal combustion engine, the one-way clutch automatically goes into idling mode which is typically known. Further, the increasing requirements for reduced fuel consumption means that friction losses in the engine must also be continuously reduced. This is why the level of friction in the one-way clutch between the roller and shaft drops to minimum value using lubrication. Especially during idling speed range. Hence one-way clutches require efficient lubrication throughout the working range. Further, wet type centrifugal clutches are used where a centrifugal clutch mounted on the crankshaft at its end, the centrifugal clutch ensures that at low to idle speeds the power transmission from the IC engine is disengaged to the rear wheel. Wet type centrifugal clutch has been used for many years and a number of lubrication system for supplying oil from a sump in the transmission chamber to plates of centrifugal clutches are known in the art. The most common form of lubrication involves immersing of clutch casing in oil which is then splashed by rotation throughout the housing over the plates
[00023] The transmission system which includes a single transmission stage, a centrifugal clutch, and driven shaft having a sprocket at its end, through which the final drive to a rear wheel is connected is known in the art. The centrifugal clutch (10c) ensures that at low to idle speeds the power transmission from the IC engine is disengaged to the rear wheel. The final drive to the rear wheel of the saddle type wheeled vehicle is usually a positive drive such as sprocket and chain arrangement. Therefore, continues lubrication is required to have more heat dissipation. Further, In vehicular engineering, various two wheelers are rated for their ability to ascend terrain, so vehicle gradeability is ensured where vehicle can ascend while maintaining a particular speed during gradient stage, Further, footprints of roads have been widespread to areas which were previously inaccessible, especially hilly areas where grade, pitch, and slope are important components hence steep gradients were a serious problem besides capability of vehicle to take gradients even on full loads as the oil in transmission chamber tends to accumulate to one side of the transmission chamber which encloses one way clutches, centrifugal clutch and many other parts. Thus, during gradient (10b) the oil accumulates to one side of the transmission chamber which makes the centrifugal clutch (10c) to run in dry state and result in rough performance of the internal combustion (IC) engine accompanied by noise and vibration resembling a rattle which increases with speed of the internal combustion (IC) engine of the vehicle (10a) as shown in Fig. 1A. Further the oil is heated to such an extent that an oil cooler generally implemented to avoid overheating of clutch and transmission. This overheating is caused due to many reasons one of the reason is combination of energy expended during slippage of clutching elements and in splashing and churning the oil in transmission chamber, & this energy converted into heat. Thus, the energy lost is not only converted into heat but also results in more clutch wear which reduces clutch life, durability & reliability. Further, such vehicles need to have low cost, high efficiency, good control throughout the entire speed range.

[00024] Moreover, any attempt to increase the volume of the oil sump leads to reduced breathing space inside the transmission system, as temperature will remain same but area will be reduced which makes the oil seal to pop out because of high pressure, or leads to clogging of air filter or leakage from crankcase side wall etc. which are all undesirable. Moreover, such vehicles need to have low cost, high efficiency, good control throughout the entire speed range including gradeability. Providing separate oil pump leads to increased number of parts, cost and major layout changes. The major layout design aspect includes mounting and availability of sump whose oil inlet should be continuously dipped in oil else it leads to priming which can make the pump nonfunctional since will not suck oil effectively. So, the non-functionality of pump makes centrifugal clutch to run in dry state which can eventually lead to failure & stalling of the engine. Furthermore, any change in existing designs of oil sump leads to increase in the size of the crankcase and modifying the existing design leads to more cost to due complex machinability of intrinsic parts.
[00025] Thus, there is a need to have an improved transmission system for a vehicle overcoming all of the problems cited & other problems known in the art. Hence, there is need of efficient transmission system in order to alleviate one or more drawbacks highlighted above, Hence the present subject matter efficient transmission system is proposed in order to alleviate one or more drawbacks highlighted above.
[00026] It is therefore an object of the invention to provide a transmission system ensuring efficient lubrication.
[00027] It is therefore another object of the invention to provide a transmission system avoiding dry running of centrifugal clutch which leads to less wear and heat.
[00028] It is another object of the invention to provide transmission system with low cost, high efficiency, good control throughout the entire speed range including grade ability.
[00029] It is yet another object of the present invention to provide a transmission system having lubrication resulting in minimum loss of the oil and immediate pickup of oil.
[00030] It is another object of the present invention to provide a transmission system having lubrication without necessity of the oil cooler.
[00031] It is yet another objective of the present invention to provide a transmission system having continuous lubrication of clutch plates with the oil which avoids overheating due to dry engagement.
[00032] It is another objective of the present invention to provide lubrication system by avoiding the external system includes separate pump, reservoir etc.
[00033] It is yet another objective of the present invention to provide the lubrication system which requires less assembly time.
[00034] In accordance with the present invention, during non-gradient the centrifugal clutch is partially immersed on oil, so when centrifugal clutch is rotating a quantity of oil is always in suspension resulting in splashing, but during gradient a retainer is configured to have sidewalls carry oil around by a centrifugal force and discharge it to the inner edges of the clutch plates so that oil is thrown out between plates and lubricate them. Importantly the oil is directed through the clutch and flows into the retainer without necessity for repeated pick up from sump. The oil path is essentially an improvement feature with a closed circuit such that oil being picked up is directed through inner surface of retainer; guided by side walls; flows directly on the clutch plates, so it results in minimum losses of oil and immediate pickup during gradient. As per first embodiment the retainer is provided on the bottom half of the centrifugal clutch making a predetermined angle ?A. As per an embodiment, the range is less than 180 degrees at the centre. The retainer as per first embodiment configured to have an arcuate or concave shape mounted on the oil pump cover using mounting means.
[00035] The retainer as per second embodiment is integrated to the housing. The retainer configured to have two diverging edges joined to form a neck when moved from the bottom to top of the housing to circumferentially cover the clutch. The retainer configured to have an inner surface. The inner surface adapted to have at least 2 milli meter gap from the clutch.
[00036] The aforesaid and other advantages of the present subject matter would be described in greater detail in conjunction with the figures in the following description with an embodiment of a two wheeled vehicle and its powertrain.
[00037] Figure 1. Illustrates a left side view of a two-wheeled vehicle (100) typically called a scooter, in accordance with an embodiment of the present subject matter. A frontward direction is indicated by an arrow F, and a rearward direction indicated by an arrow R provided in the top center of first figure. The vehicle is extending from the front direction to the rear direction along the vehicle longitudinal axis (F-R). In an embodiment; the two-wheeled vehicle (100) of the present subject matter comprises a frame which is conventionally an under-bone chassis frame which provides a generally open central area to permit “step-through” mounting by a rider. The vehicle (100) illustrated, has a step-through type frame assembly. The step-through type frame assembly includes a head tube (103), a down tube (104) and a sub frame (105). The frame assembly extends from a front portion F to rear portion R of the vehicle. Further, the frame assembly extends downward from the anterior portion of the head tube (103) and then extends to a rear portion of the vehicle (100) in inclined manner. The pair of side-tubes (not shown) extends rearwardly from the other end of the main tube (not shown) and supports vehicular attachments such as a seat assembly (115), fuel tank assembly (not shown), a utility box (not shown) and a pillion hand rest (122). In the rear end of the two wheeled vehicle (100) a rear lamp assembly (119) and a rear mud-guard/rear fender (116) is provided. The rear guard (116) having reflector (113). The head tube (103) supports a steering tube (not shown) and further connected to the front suspension system (117) at the lower end. A handlebar support member (not shown) is connected to an upper end of the steering tube and supports a handlebar assembly (121) which is having a mirror (124). Two telescopic front suspension systems (117) (only one is shown) support a front wheel (113). The upper portion of the front wheel (120) is covered by a front fender (112) mounted to the lower portion of the steering shaft. There is a front brake (not shown) and a rear brake (not shown) arranged on the front wheel (120) and a rear wheel (108) respectively. The rear wheel (108) is supported towards the rear side of the frame assembly by a swing arm (123) which is horizontally coupled swingably to the rear of the frame assembly of the two wheeled vehicle (100) through a rear suspension system (118). The traction motor (107) integrated to a rear wheel (108). In a preferred embodiment, the traction motor (107) is hub mounted on the rear wheel (108). An on-board battery (not shown) drives the traction motor (107). The internal combustion (IC) engine (106) is mounted on a swing arm (123), which is swingably connected to the down tube (104) using a toggle link. The frame assembly is covered by plurality of body panels, mounted on the frame assembly and covering the frame assembly, including a front panel (102), a leg shield (109), an under-seat cover (110), and a left and a right side panel (111). A glove box may be mounted to a leg shield (109). Over the rear wheel (108) a body panel is disposed of to support the seat assembly (108). The internal combustion (IC) engine (106) transfers the drive to the rear wheel (108) as it is coupled to it. The internal combustion (IC) engine (106) comprises a transmission system, said system disposed leftward of the internal combustion (IC) engine (106) in the vehicle width direction.
[00038] A front fender (112) is covering the front wheel (113). A floorboard (114) is provided at the step-through space provide above the down tube (104). A seat assembly (115) is mounted to the sub frame (105). A utility box (not shown) is disposed below the seat assembly (115). A fuel tank (not shown) is positioned below the utility box. A rear fender (116) is covering at least a portion of the rear wheel (108) and it is positioned below the fuel tank (not shown). One or more rear suspension(s) (118) are provided in the rear portion of the vehicle (100) for comfortable ride. The vehicle (100) comprises of plurality of electrical and electronic components including a headlight (101), a rear lamp assembly (119), a transistor controlled ignition (TCI) unit (not shown), a starter motor (not shown).
[00039] Figure 2 illustrates a left side view of the rear portion of the two wheeled vehicle (100) illustrating a swingable internal combustion (IC) engine (106) in accordance with the embodiment of the present subject matter. The internal combustion (IC) engine (106) comprises a cylinder block (202) includes a cylinder bore (not shown), a piston (not shown) reciprocating in the cylinder bore (not shown), a cylinder head (207) located above the cylinder block (202) and a combustion chamber interposed between the cylinder head (207) and the cylinder block (202). The cylinder head (207) comprises intake valve (not shown) and outlet valve (not shown) which control the intake of air fuel mixture inside the combustion chamber, and controls the exit of exhaust gases after combustion respectively. The cylinder head (207) is covered by the cylinder head cover (201) during operation of the internal combustion (IC) engine (106), the burning of air fuel mixture occurs in the combustion chamber. The forces generated due to combustion of air fuel mixture is transferred to a piston (not shown) which is capable of reciprocating inside the cylinder block (202), and this reciprocating motion is transferred to rotary motion of the crankshaft (301) (as shown in Fig. 3) though a connecting rod (not shown) by the slider crank mechanism. Typically, in a two wheeled vehicle (100) such as a scooter, a swinging internal combustion (IC) engine (106) is located below the seat assembly (115) at a lower rear portion of the vehicle (100). The internal combustion (IC) engine (106) is swingably supported by and attached to the frame assembly of the two wheeled vehicle (100). A single speed transmission assembly forms a part of the internal combustion (IC) engine (106) and is disposed on the rear portion of the internal combustion (IC) engine (106) and mounted so as to be disposed on right or left of the two wheeled vehicle (100). In first embodiment, the transmission assembly is disposed so as to be oriented towards the left of the two wheeled vehicle (100) as viewed from the rear direction of the two wheeled vehicle (100). The transmission assembly is enclosed within a crankcase LH (204) on the rear side of the internal combustion (IC) engine (106) and the transmission assembly is enclosed by a housing (203) thus forming an enclosed space. The wheel sprocket (206) is disposed outside the housing (203) which receives rotary motion from the output/ driven shaft (302) (as shown in Figure 3) of the gear train mechanism on the rear wheel (108). The final drive to the rear wheel (108) of the two wheeled vehicle (100) is usually a positive drive such as sprocket and chain arrangement (205)
[00040] Figure 3 illustrates the left side view of the internal combustion (IC) engine (106) and transmission assembly where some constituent parts are omitted. The primary transmission is from the crankshaft (301) to the driven shaft (302) through transmission means (305). The transmission means (305) transfers power from the internal combustion (IC) engine (106) to driven shaft (302). The transmission guiding and tensioner assembly (307) is mounted on crankcase LH (204) using mounting means. The mounting means includes bolt (309). The guiding and tensioner assembly (307) is in slideable contact with the transmission means (305) which guide the transmission means (305) during its travel. Further the motor having pinion gear (not shown) rotates the back plate (505a) (as shown in fig. 5) through the intermediate gear (304) via ring gear (303). The back plate (505a) (as shown in fig. 5) enables the rotation of the crankshaft (301) for cranking the internal combustion (IC) (106) and an ignition system (not shown) enables delivering of spark. A retainer (310) is provided which is disposed between housing and oil pump cover such that it makes a predetermined angle ?A, at the central axis of the crankshaft (301) said angle is less than 180 degrees at the center of the clutch (308) when disposed at bottom half of the clutch (308). The predetermined angle ?A as per an embodiment ranges from 50 degrees to 180 degrees. Angle less than 50 degrees is inadequate in effective lubrication and angle more than 180 degrees in redundant & undesirable.
[00041] Figure 4 illustrates the exploded view of the present embodiment where it represents the crankcase (204R, 204L) in which transmission assembly is present which extends rightward (RH) and leftward (LH) in the internal combustion engine (106) width direction said crankcase (204R, 204L) comprising of a top surface, and a bottom surface, and a plurality of side surfaces of the crankcase, wherein the side surfaces are substantially vertical and configured to extend between the top surface and the bottom surface. The part extended in rightward (RH) direction is known as a crankcase RH (204R) and the part extended in leftward (LH) direction is known as a crankcase LH (204L). Similar to the crankcase (204R, 204L), a crank shaft (301) also extends rightward (RH) and leftward (LH) in the internal combustion (IC) engine (106) width direction. This extension results in two parts of the crankshaft (301), first one is known as a crankshaft RH as the crankshaft extends in rightward (RH) direction and second one is known as a crankshaft LH as the crankshaft (301) extends in leftward (LH) direction. The crankcase LH (204L) is covered by housing (203). This housing makes the system leak proof and enables effective lubrication. In the crankcase LH (204L), of horizontally disposed internal combustion engine (IC) engine (106) such as that of scooter-type two-wheeled vehicles (100), an oil sump (not shown) is provided in the bottom-side of the crankcase LH (204L) for continuous lubrication and cooling of a piston (not shown) and a plurality of piston cylinder wall (not shown) and other parts of the internal combustion (IC) engine (106). The lubrication and cooling of the piston (not shown), the plurality of piston cylinder wall (not shown) and other parts of the internal combustion (IC) engine (106) begins once an operation cycle of thermal energy conversion into mechanical energy begins. Once the operation cycle starts, rotation of the crankshaft (301) also starts. The transmission oil chamber ensures the continuous lubrication of the transmission means (305), Further the lubricant sump (not shown) is also provided in which desired lubricant level is maintained and to ensure that the components like transmission means (305) at least partially immersed in the lubricant. The motion of the transmission means (305) causes lubricant splashing and lubrication of the components. A gauge oil level (402) is also provided on the crankcase RH (204R) which enables the user to check the lubricant oil level. A spring-loaded centrifugal clutch (308) is fixedly attached to the crankshaft LH (301L) using fastening means. The fastening means includes nuts (401). The centrifugal clutch (308) ensures that at low to idle speeds the power transmission from the internal combustion (IC) engine (106) is disengaged to the rear wheel (108) (as shown in fig. 1) as spring loaded centrifugal shoe unit fixedly attached to the crankshaft (301) and capable of expanding and engaging with the outer hub (308a) on rotation of the crankshaft (301) beyond a predetermined speed thereby rotates drive sprocket (405). The drive sprocket (405) is welded with the outer hub (308a) known as drum. So on attaining certain rpm the drive sprocket (405) rotates the driven sprocket (306) through transmission means (305). The transmission means (305) connects the drive sprocket (405) to a corresponding driven sprocket (306). The direction of rotation of the transmission means (305) is made common with the internal combustion (IC) engine (106) and the rear wheel (108). To lubricate the centrifugal clutch (308) a retainer (310) is provided which is mounted on the rear side of the oil pump cover (403), further the retainer (310) is located on the bottom half of the centrifugal clutch (308).
[00042] Figure 5 illustrates cut section of figure 2 taken along plane A-A’ and represents the crankcase (204R, 204L) in which transmission assembly is present which extends rightward (RH) and leftward (LH) in the internal combustion engine (IC) engine (106) width direction, the cylinder head (207) is covered by the cylinder head cover (201) which is mounted on it using mounting means (501). During operation of the internal combustion (IC) engine (106), the burning of air fuel mixture occurs in the combustion chamber. The forces generated due to combustion of air fuel mixture is transferred to a piston (not shown) which is capable of reciprocating inside the cylinder block (202) and this reciprocating motion is transferred to rotary motion of the crankshaft (301) though a connecting rod (not shown) by the slider crank mechanism. Further, as per the internal combustion engine (IC) engine (106) construction, on the crank shaft LH a gear oil pump drive (GOPD) (510) is mounted and the gear oil pump drive (GOPD) (510) are mated with an oil pump assembly (not shown). Due to the rotation of the crankshaft (301), the gear oil pump drive (GOPD) (510) also starts rotating, since the gear oil pump drive (GOPD) (510) is in contact with the oil pump assembly (not shown) it results in the movement of lubricant oil from oil sump (not shown) to lubricate and cool the piston (not shown), the plurality of piston cylinder wall (not shown) and other parts of the internal combustion (IC) engine (106). The crankcase RH (204R) having cooling system mounted using fastening means on an extended portion of crankshaft (301) juxtaposes outside the crankcase RH (204R) over which the cooling system is operably secured. The cooling system in general comprises a shroud (not shown) with plurality of ribs (not shown), and a cooling fan (not shown). The cooling fan (not shown) operates at a same speed of crankshaft (301) and generates air flow. The cooling system efficiency is directly proportional to the air flow coming out from the cooling fan (not shown). The cooling fan (not shown) throws out more air coming out from the internal combustion (IC) engine (106). In order to increase the cooling rate, it is recommended to have higher fan air flow rate so shroud (not shown) is provided ahead of the cooling fan (not shown). The internal combustion (IC) engine (106) comprises the transmission assembly freely mounted on an extended portion of the crankshaft LH (301L). A portion of crankshaft (301) juxtaposes outside the crankcase LH (204L) over which the transmission assembly is operably secured. The transmission assembly is designed to have the centrifugal clutch (308) with two one-way clutches (505, 506). The first one-way clutch assembly (505) having back plate (505a). The first one-way clutch assembly (505) is held in position on the crankcase LH (204L). The crankcase LH (204L) is completely enclosed on its sides except for relevant opening for accommodating the crankshaft (301) and the output shaft/driven shaft (302). An oil pump cover (403) is supported by crankcase LH (204L).
[00043] A first one-way clutch assembly (505) comprises back plate (505a) mounted on crankshaft (301). Ahead of first one-way clutch assembly (505) a drive sprocket (405) is mounted on the crankshaft LH (301L). A spacer (509) is placed between the drive sprocket (405) and one-way clutch assembly (505) (as shown in Fig. 5) to maintain gap which avoids rotation. The motor having pinion gear (not shown) rotates the back plate (505a) through the intermediate gear (304) (as shown in fig. 3) via ring gear (303) (as shown in fig. 3). The back plate (505a) enables the rotation of the crankshaft (301) for cranking the internal combustion (IC) (106) and an ignition system (not shown) enables delivering of spark. The second one way clutch assembly (506) is mounted on the driven shaft (302) using fastening means. The fastening means includes nuts (401). The power is transmitted from the drive sprocket(405) to the second one way clutch (506) through driven sprocket(306) via transmission means(305), wherein said second one way clutch assembly (506) comprises back plate (506a) which is internally splined and mounted on external splines on the end of the driven shaft(302) disposed parallel to the crankshaft (301) towards the rear of the internal combustion (IC) engine (106) and is supported by roller bearings (507) on the rear portion of the crankcase LH (204L).The power from back plate(506a) is transmitted to the driven shaft(302) and then finally to the rear wheel(108) through second driven sprocket (508) where rear wheel sprocket (206) is connected to second driven sprocket (508) through the chain arrangement (205).The rear wheel sprocket (206) is mounted on the wheel axle (502).The first one way clutch assembly (505) ensures that, the drive is not transferred from the crankshaft (301) to the ring gear (303).The driven sprocket (306) engages with the rollers (504) of second one way clutch assembly (506) , where the second one way clutch assembly (506) transmit power to back plate (506a) as both are bolted. Moreover, the second one way clutch assembly (506) is configured to prevent the rotary motion drive from transferring back to the crankshaft (301) and the transmission assembly from the driven shaft (302) during the ideal running of vehicle on road and when vehicle is powered by motor. The crankshaft (301) is mounted with an electrical machine (503). In one embodiment, the electrical machine (503) is connected to the crankshaft (301). In a preferred embodiment, the electrical machine (503) includes magneto or integrated stator generator (ISG). The integrated stator generator (ISG) help in reduction of size of motor. Hereinafter, the terms electrical machine (503) and magneto (not shown) are interchangeably used. The magneto (not shown) includes a rotor (not shown) and a stator (not shown). The rotor (not shown) is connected to the crankshaft (301). The rotor (not shown) includes magnetic members and the stator (not shown) is provided with plurality of windings (not shown). The retainer (310) is disposed between the driven shaft (302) and crankshaft (301) and specifically said retainer (310) is disposed on the bottom half of the centrifugal clutch (308).
[00044] Figure 6 illustrates the perspective view as per present embodiment. The oil pump cover (403) configured to have two extended boss (602) with mounting holes where the retainer (310) is mounted using mounting means, the mounting means includes at least two bolts (601). The retainer assembly (310) configured to have side walls (603) where the side walls prevents spilling of oil from the retainer (310).
[00045] The retainer (310) is formed with an arcuate or concave shape. The retainer (310) as per present invention configured to have plurality of spaced apart yokes (604) along at least one side of the retainer (310) facing oil pump cover (403); said yokes (604) configured to have a plurality of apertures for receiving respective mounting means to removably mount the retainer (310) on the extended boss (602) of the oil pump cover (403).
[00046] The yokes (604) orient the retainer in predetermined angular range ?A. Where the retainer (310) is supported by at least one extended boss (602) such that it covers the bottom half of the centrifugal clutch (308). The inner surface of the retainer (310) adapted to have at least 2 milli meter gap from the centrifugal clutch (308) such that it ensures efficient lubrication during gradient stage. As various parts in power transmission are subject to various stresses, predominately thermal stress and residual stress. The residual stresses are internal stress. In transmission system various parts inside the crankcase (204L, 204R) interact with each other like chain and sprocket, where hardness of various components varies and because of that few parts subjected to premature erosion over a period of time. The eroded debris of eroded parts retained inside the transmission unit is in form of sludge which can only be removed during the overhauling of engine. Hence the retainer (310) as per first embodiment makes a predetermined angle ?A of not more than 180 degree at the bottom half of the centrifugal clutch (308). Moreover, the gap of at least 2 milli meter between the centrifugal clutch (308) and retainer (310) assures proper drainage of sludge, as less gap makes the sludge to remain intact inside the centrifugal plates which will dirt the new oil after servicing and also affects other mating parts like one-way clutch and back plate leading to poor durability & life.
[00047] Further as per another embodiment the oil pump cover (403) configured to have at least two extended boss (602) wherein one extended boss (602) provided with mounting holes where the retainer (310) is mounted using mounting means, another extended boss (602) configured to work as stopper to resist the rotational movement of the retainer (310). This stopper i.e. another extended boss ensures that retainer (310) is disposed in the predetermined angle ?A ranges less than 180 degree at the center of the clutch (308) when disposed at bottom half of the clutch (308).
[00048] Figure 7 illustrates the partial cut top view of the engine and transmission assembly and a perspective view of the housing which is configured to have retainer. As per figure 7(a) the housing (701) is attached to the crankcase LH (702). The housing (701) configured to have a retainer (703) which is integral part of the housing (701). The retainer (703) extends inwardly in the width direction (C-C’) of the vehicle (100) such that it resists the accumulation of oil and avoids dry running of the centrifugal clutch (308). The retainer (703) circumferentially covers major part of the centrifugal clutch (308).
[00049] Figure 8 illustrates a perspective view of the housing which is configured to have retainer (703). The retainer (703) extends from the top of the housing (701) to the bottom side of the housing (701) to cover major portion of the centrifugal clutch (308). The retainer (703) as per an embodiment is configured to have special profile where two diverging edges (703A) and (703B) joined to form a neck i.e. single edge (703C) when moved from the bottom to top of the housing (701). The diverging edges (703B) configured to retain the oil during splashing action by the rotation of parts. Further this special design ensures better rigidity to the retainer (703) and to the housing (701) as well.
[00050] The present invention as per first and second embodiment can also be implemented in existing transmission assembly without extensive design and layout changes, which is easily accessible.
[00051] The present invention as per first and second embodiment is also implementable with minimal changes in existing layout as it leads to minimum modification of frame component supporting the internal combustion (IC) engine. Furthermore, there can be standardization of parts wherein single speed and two speed can be introduced based on customer needs and requirements.
[00052] The present invention as per one and second embodiment ensures the transmission is compact, low cost & can be accommodated in an existing design of the internal combustion (IC) engine and transmission assembly since it results in reduced noise, and low vibration operation and efficient working of the internal combustion (IC) engine.
[00053] The present invention as per first and second embodiment ensures continuous lubrication excreting through the retainer which continuously lubricates the centrifugal clutch during gradient.
[00054] The present invention as per first and second embodiment counters the excess heat at large duration by avoiding dry engagement of clutch.
[00055] The present invention as per first embodiment can also be implemented without major change in design of the crankcase (204L, 204R) as in first case retainer (310) is introduced from the bottom of centrifugal clutch (308) without any significant modification of the existing design which further reduces the cost as less complex machinability of intrinsic parts is required.
[00056] The present invention as per first and second embodiment ensures ease of serviceability as the retainer can be removed from the transmission without detaching the whole assembly.
[00057] The present invention as per first and second assembly leads to less assembly time which leads to more production rate as the part count is reduced and the whole assemble remain within ergonomic reach of the workmen during assembly because as per first embodiment the retainer (310) can be mounted using only two bolt (601), Further as per second embodiment the retainer (703) is integrated to housing (701).
[00058] 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.

List of references
F- Front
R –Rear
C – C’ – Lateral axis
Y – Y’ – Longitudinal axis
10a – Vehicle
10b – Gradient
10c – Centrifugal clutch
100 – Vehicle
101 - Headlight
102 - Front panel
103 - Head tube
104 - Down tube
105 - Sub frame
106 - Internal combustion (IC) engine
107 - Traction motor
108 - Rear wheel
109 - Leg shield
110 - Under-seat cover
111 - A left and a right side panel
112 - Front fender
113 - Reflector
114 - Floorboard
115 - Seat assembly
116 - Rear fender
117 – Front suspension(s)
118 – Rear suspension
119 – Rear lamp assembly
120 – Front wheel
121 – Handle bar assembly
122 – Pillion handle rest
123 – Swing arm
124 – Mirror
201 – Cylinder head cover
202 – Cylinder block
203 – Housing
204L – Crankcase LH
204R - Crankcase RH
205 – Chain arrangement
206 – Wheel sprocket
207 – Cylinder head
301 – Crankshaft
301L – Crankshaft LH
302 – Driven shaft/output shaft
303 – Ring gear
304 – Intermediate gear
305 – Transmission means
306 – Driven sprocket
307 –Guide member assembly
308 – Centrifugal clutch
308a – Outer hub
309 – Bolt
401 – Nut
402- Gauge oil level
403 – Oil cover
404 – Bolt
405 – Drive sprocket
501 – Mounting means
502 – Second driven shaft
503 – Electrical machine
504 – Roller
505 – First one-way clutch
505a – Back plate
506 – Second one-way clutch
506a – Back plate
507 – Roller bearing
508 – Second driven sprocket
509 – Spacer
510 –Gear oil pump drive (GOPD)
601 – Bolt
602 – Extended boss
603 – Side wall
604 - Yoke
605 – Fastening means
606 – Electrical machine
607 – First one-way clutch assembly (Back plate 607a)
608 – Second one-way clutch (Back plate 608a)
609 – Roller bearing
701 – Housing
702 – Crankcase
703 – Retainer
703A, 703B – Diverging edge’s
703C - Neck