EP3987168A2

EP3987168A2 - An engine

Info

Publication number: EP3987168A2
Application number: EP20742512.5A
Authority: EP
Inventors: Kandregula SRINIVASA RAO; Thangaraj BOOPATHI RAJ
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2019-06-18
Filing date: 2020-06-16
Publication date: 2022-04-27
Also published as: WO2020255162A2; CN113994086A; CN113994086B; WO2020255162A3

Abstract

The present invention relates to an engine having a crankcase enclosing a transmission assembly including a crankshaft and a clutch member, and a crank torque actuation device (A). The cranking torque actuation device includes at least one driven shaft (311) mounted on a cover having a lubrication path, at least one axially movable ratchet gear (310) mounted on said driven shaft (311), at least one ratchet nut (312), said ratchet nut (312) mounted on the crankshaft (302), at least one oil seal member (313) disposed between the ratchet nut (312) and the driven shaft (311), and at least one idler gear (309) drivingly connecting a drive gear (306) and the ratchet gear (310). Said ratchet gear (310) rotates about an axis of driven shaft (311) with a predetermined movement to engage with a complementary shaped ratchet portion (312a).

Description

AN ENGINE

TECHNICAL FIELD

[0001] The present subject matter relates to a vehicle. More particularly, the present subject matter relates to a cranking torque actuation device and lubrication system of the vehicle.

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 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.

[0003] Foot operated starters for internal combustion engines are known in the art, for instance, in starting motorcycles and scooters. Such starters are operated by the rider's foot and leg wherein a rapid "kick' of the operating lever by the leg creates the starting torque. Such starters have commonly been known as“kick starter” which are directly connected to the engine crankcase, and integrally form a portion of the engine structure.

[0004] It is known in the art to have a kick start assembly coupled with the internal combustion engine that requires a large space to functionally integrate both units. With a growing trend of downsizing or compacting overall layout of the vehicle, it becomes challenging to dispose all elements of kick start assembly and the internal combustion engine in a compact layout and still avail the desired efficiency of the system. For example, lubrication of the kick start assembly and the internal combustion engine in a compact layout becomes an issue, as a lubrication system also to be disposed with the overall assembly, thereby increasing overall size of the assembly. Owing to the above challenges, manufacturers end up having kick start mechanism incurring high cost. Thus, there is a need to provide an improved kick-started system/starter torque actuation device overcoming one or more problems in known art.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] The detailed description is described with reference to an embodiment of a two wheeled saddle type moped vehicle with the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.

[0006] Fig 1A (prior art) is a top cut section view of a powertrain with transmission assembly with starter torque actuation device.

[0007] Fig. 1 is a left side view of an exemplary vehicle, as per preferred embodiment of the present invention.

[0008] Fig. 2 is a left side view of a powertrain with transmission assembly with cranking torque actuation device, as per preferred embodiment of the present invention.

[0009] Fig. 3 is a top cut section view of a powertrain with transmission assembly accompanied with a local isometric view of the starter torque actuation device, as per preferred embodiment of the present invention.

[00010] Fig. 4 is a sectional perspective view of the powertrain with transmission assembly showing oil path and an enlarged view of the injection and ejection holes as per preferred embodiment of the present invention.

DETAILED DESCRIPTION

[00011] 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, an internal combustion (IC) engine described here operates in four cycles. Such an internal combustion (IC) engine is installed in three or four wheeled vehicle. It is contemplated that the concepts of the present invention may be applied to other types of vehicles employing the similar transmission within the spirit and scope of this invention. 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 unless otherwise mentioned, refers to a front to rear axis relative to the vehicle, while a lateral axis unless otherwise mentioned, refers generally to a side to side, or left to right axis relative to the vehicle. The detailed explanation of the constitution of parts other than the present subject matter which constitutes an essential part has been omitted at suitable places. As per an aspect of the present subject matter, the word powertrain has been interchangeably used for engine throughout the specification in light of scope and spirit of the invention.

[00012] As in automobiles torque and speed are important parameters, these can vary as per different segment of the vehicle; likewise, the saddle type vehicles 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 powertrain since at higher torque requirements the fuel economy drops. The critical issues involved in the design of the transmission system are to consider 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 multiple gear ratio with ability to switch between various speeds. There are many modes of switching like manually or automatically. It is known in the art (as shown in Fig. 1A) where cranking torque actuation device comprises the actuation shaft (701) which is connected to a ratchet mechanism (703a, 703b). The ratchet mechanism (703a, 703b) is mounted on the actuation shaft (701). When the kick lever (707) is actuated by foot of a rider, the ratchet (703a) moves and engages with kick starter gear (703b) having ratchet face, which meshes with the ratchet (703). The kick starter gear (703b) is operably connected to the crankshaft (700) via idler gear (704). Force from kick starter gear (703b) is transmitted to the idler gear (704), wherein said idler gear (704) is freely rotatably mounted on the drive shaft (706). The force is transmitted from the idler gear (704) to the crankshaft (700) via a gear pump oil drive (705), where gear pump oil drive (705) is mounted on the crankshaft (700). Typically, a specified gear ratio is maintained to get desired torque to crank the powertrain. On withdrawal of pressure from the foot, the return spring (702) withdraws the kick lever (707) to starting position. In the specified layout the idler gear (704) continuously rotates with the drive shaft (706) even after starting operation, this phenomenon of continuous rotation of the idler gear (704) results in excess wear, cost, higher inertia losses for the powertrain, and also require higher number of parts. Further any change in size of the idler gear (704) leads to rattling or winning noise. The rattling is caused due to more center distance between idler gear

(704) and gear pump oil drive (705). In order to overcome the rattling issue, when the center distance is decreased between idler gear (704) and gear pump oil drive

(705), another issue related to winning sound arises. In order to overcome above mentioned issues high grade material may be used that ensures better rigidity resulting in low wear thereby reducing rattling and winning issues. However, idler gear (704) of high-grade material leads to more weight and cost.

[00013] Hence there exists a challenge to design a compact power unit layout which is compact laterally, address one or more of above mentioned and related issues, while still ensuring required function of kick start with single speed transmission.

[00014] In addition, the crank pin and crankshaft area as well as the bearings require lubrication for good performance, low friction losses and durability, the cranking actuation mechanism is disposed on the side of the magneto which enables the lubrication path to be routed through a bore passage passing through the crankshaft from the wet clutch side. Such powertrains typically have a dry magneto implemented on one side & this necessitates the kick start to be disposed on the opposite side in combination with a wet clutch to effectively lubricate the system as well as achieve compact width & packaging. However, configuring the cranking actuation mechanism on the side of the dry magneto which ideally would be preferable since it has an intermediate operation and it needs to disengage preferably through a lateral sliding movement. In such ideal scenario, after completing starting action, the cranking system will lead to a gap in the continuity of the crankshaft, thereby making it unviable to achieve lubrication & thus making it highly undesirable choice by design. Also achieving compact layout posed additional difficulties. Owing to the above conflicting challenges, manufacturers end up having a compromise of using an idle gear type starting torque mechanism incurring high cost and other drawbacks like excess inertia losses in powertrain owing to the compromise. There exists a challenge of designing a compact powertrain layout with lower inertia, friction losses, a smaller number of parts, while ensuring adequate lubrication for the crank pin, crankshaft, clutch & the bearings. There is a need for an efficient & compact starter torque actuation device which can enable torque transfer over to the powertrain at intermittent interval while still enabling lubrication of being supplied to the rotating friction elements cutting across the same torque actuating device or system while the actuating device is operated with dry lubrication.

[00015] Furthermore, in a vehicle to start the engine of a conventional moped the rider put the vehicles on stand and goes to the other side i.e. conventionally kick lever is disposed on right hand side (as shown in fig. la) and side stand on the left-hand side, hence it makes kicking operation uncomfortable. Due to this arrangement, it becomes difficult for the rider to apply the maximum push on the foot pedal while simultaneously balancing the vehicle with one hand while astride the same. With an engine difficult to start, it is possible to cause back injuries, during starting, and the use of a kick-starting on left side does not have the appeal of a kick starter to operators and especially to old people and female riders.

[00016] Moreover, the vehicles configured to have centrifugal clutch, said centrifugal clutch having clutch drum, so typically at 3,000 rpm (revolutions per minute) only a small portion of the centrifugal weights touch the clutch drum and the torque transmitted is small. As a result, the centrifugal clutch may slip over a wide rpm range, typically between 2,500 and 6,500 rpm for a 100-cc vehicle. The slipping range of the centrifugal clutch is very important as the centrifugal clutch is in the slipping mode frequently in slow corners or at the start of the vehicle. A broad slipping range results in loss of powertrain power in heat, excessive clutch wear and less efficient acceleration. This heat generation leads to more temperature inside the crankcase necessitating more cooling and lubrication. However, any paucity of adequate lubrication and cooling further leads to less durability of parts. Hence it is a challenge for automobile players to design a kick starter assembly which assures efficient lubrication and more rider comfort within a compact layout of the vehicle and at the same time to keep the design compact and lightweight while overcoming all above stated problems & other problems from known art.

[00017] Hence the present powertrain with the starter torque actuation device is proposed in the present subject matter in order to alleviate one or more drawbacks highlighted above.

[00018] It is therefore an aspect of the invention to provide a starter torque actuation device ensuring required function of the starter torque actuation device with single speed transmission, and which is compact and is configured to provide efficient lubrication.

[00019] It is yet another aspect of the invention to provide a shorter route for the lubrication which results in less complex machining of the parts.

[00020] It is an aspect of the invention to provide starter torque actuation device configured to have less weight and cost.

[00021] It is an aspect of the present of the invention to reduce the higher inertia losses for the powertrain which results in more fuel economy and less power loss.

[00022] It is yet another aspect of the present invention to provide a starter torque actuation device which gives more comfort to the operator while kicking operation.

[00023] The present invention relates to the starter torque actuation device. As per an aspect of the present subject matter a foot pedal is disposed outwardly operable by the rider manually on the left side of the vehicle so this action rotates the operating lever which is connected to the exterior end of the actuation shaft, hence the force is transmitted from the actuation shaft to drive gear. The drive gear (preferably spur gear type) is in direct contact with the spur gear portion of idler gear. The idler gear is a hybrid type gear having spur gear portion and helical gear portions. The helical gear portion of idler gear being operatively associated with the helical gear portion of the ratchet gear. The ratchet gear is adopted to rotate about the axis of driven shaft with a predetermined movement when force is transmitted to the ratchet gear. The force from idle gear which is in helical - helical teeth meshing with the ratchet gear causes the ratchet gear to rotate which is resisted by guide spring. The guide spring resist the rotation of ratchet gear which makes the ratchet gear to move forward, resulting which the ratchet gear engages with the ratchet nut which is having complementary shaped ratchet portion. The ratchet gear substantially compresses an oil seal member which is disposed between driven shaft and ratchet nut. So, when ratchet nut is subjected to rotational force, it in turn rotates the crankshaft to crank the powertrain. On withdrawal of pressure from the foot pedal, the return biasing member withdraws the operating lever to starting position which creates a gap between the driven shaft and crankshaft. In order to overcome this technical challenge n oil seal member configured to be disposed between the driven shaft and ratchet nut which ensures continuous lubrication, through a lubrication path, after disengagement of the ratchet gear and ratchet nut. The oil seal is so configured to circumscribe & form an enclosure sealing around a predetermined operative gap between the two torque transferring shafts such that it has adequate land to permit lateral movement of the actuation shaft drive shaft from the crankshaft after completing the cranking to successfully disengage the kick starting system/starter torque actuation mechanism while still enabling the lubrication oil from the oil pump which is typically disposed on the wet clutch side, to be supplied to the crankshaft & the crankpin thereby ensuring supply of lubrication to the critical areas which otherwise would run dry & fail in no time. Gears like the drive gear and the idler gear becomes stationary after kicking operation, that results in lower inertia losses for the powertrain thereby reducing the power consumption by the gears. Moreover, the rattling and wining noises are also reduced because of the proposed layout. As per another embodiment of the present subject matter the starting system can be actuated by an electrical device like a starter motor or an ISG (Integrated Starter Generator) or an ISS (Integrated Start Stop) device or the like. As per another embodiment, the current starting torque actuation system or device can be implemented in different types of powertrains e.g. IC engine, Hybrid etc. having a challenge of compact layout, torque transfer over intermittent intervals with continuous lubrication transfer across the same shaft axis while the torque transfer is disengaged.

[00024] The aforesaid and other advantages of the present subject matter will be described in greater detail, in conjunction with exemplary embodiments of a saddle type two wheeled vehicle with reference to the figures 1-4, in the following description.

[00025] Fig. 1. illustrates a left side view of an exemplary two-wheeled type-through type vehicle, in accordance with an embodiment of present invention. The vehicle (100) has a mono-tube type frame assembly (102) extending from a front portion (F) to a rear portion (R) in a longitudinal axis (F-R) of the two wheeled vehicle (100), which acts as the skeleton for bearing the loads. The frame assembly (102) extends from a head tube (103) in the front portion (F) of the vehicle till the vehicle rear portion (R). A steering shaft (not shown) is inserted through the head tube (103) and a handle bar assembly (105) is pivotally disposed on it. The steering shaft is connected to a front wheel (104) by one or more front suspension(s) (106). A front fender (107) is disposed above the front wheel (104) for covering at least a portion of the front wheel (104). A fuel tank (115) is mounted on the downward portion of the frame assembly (102) and it is disposed in the front portion (F). The frame assembly (102) forms a substantially horizontal step-through portion (114) with a floorboard to enable step-through mounting of a rider and to assist in carrying heavy loads. The powertrain (101) is mounted on the frame assembly (102) below the step-through portion (114) forming a low slung powertrain mounting. As per an embodiment, the powertrain is a single speed transmission power unit. In an embodiment, a piston axis of the engine is horizontal i.e. parallel to a longitudinal axis of the vehicle (100). A swing arm (108) is swingably connected to the frame assembly (102). A rear wheel (109) is rotatably supported by the swing arm (108). One or more rear suspension(s) (110) are connecting the swing arm (108) at an angle, to sustain both the radial and axial forces occurring due to wheel reaction, to the frame assembly (102). A rear fender (111) is disposed above the rear wheel (109). A seat assembly (112A, 112B) is disposed at a rear portion (R) of the step-through portion for seating of the rider. In an embodiment, the seat assembly (112A, 112B) includes a rider seat (112A) and a pillion seat (112B). Further, the seat assembly (112) is positioned above the rear wheel (109). The vehicle is supported by a center stand (113) mounted to the frame assembly (102). The powertrain (101) is connected to the rear wheel (109) through a transmitting means, such as in the present embodiment sprockets (not shown) linked to each other through a chain drive.

[00026] Fig. 2 illustrates the side view of the powertrain (101). The powertrain is made up of a cylinder head (202), cylinder block (203), crankcase (206) and a cylinder head cover (201). The crankcase (206) is made up RH crankcase (206R) (as shown in Fig 3), LH crankcase (206L), and a cover (204). The cover (204) is disposed on the left-hand side of the powertrain (101) adjacent to the LH crankcase (206L) and encloses a transmission assembly. The powertrain (101) includes an, an air intake system (not shown), an exhaust system (not shown), and a starter torque actuation device (A) using an operating lever (205) having foot pedal (207).

[00027] Fig. 3 illustrates the cross-sectional view (X-X) of the powertrain (101) and a transmission assembly according to the embodiment of the present subject matter accompanied with a local isometric view. The powertrain (101) comprises a reciprocating piston (301) reciprocating within the cylinder block (203), and a rotatable crankshaft (302). Combustion occurs when air fuel mixture is burnt in the combustion chamber (303) which transfers the pressure created during combustion to the reciprocating piston (301). The reciprocating motion of the piston (301) is converted to the rotary motion of the crankshaft (302) by a connecting rod (304) through a slider crank mechanism. The rotary motion of the crankshaft (302) is transferred to an engine sprocket (not shown) through the transmission assembly and a gear train mechanism (317, 318). The powertrain (101) comprises the transmission assembly freely mounted on an extended portion of the LH crank shaft (302L). An output shaft (315) is disposed parallel to the crankshaft (302) towards the rear of the powertrain (101) and is supported by two roller bearings (316). A driving gear member (317) is freely mounted on the LH crank shaft (302L) obtaining rotary motion from the transmission assembly and this rotary motion is transferred to the driven gear (318). The driving gear member (317) is meshed with a first driven gear (318) mounted on said output shaft (315), and the transmission ratio between the driving gear member (317) and first driven gear (318) provides a gear ratio multiplication. One half of a crankshaft (302) juxtaposes outside the LH crankcase (206L) over which the transmission assembly is operably secured. The LH crankcase (206L) is completely enclosed on its sides except for relevant opening for accommodating the crankshaft (302) and the output shaft (315). In an embodiment, the crankshaft (302) is configured to have an oil path. Typically, the transmission assembly includes a spring-loaded centrifugal clutch (319) fixedly attached to the LH crankshaft (302L) using fastening means. The RH crankcase (206R) encloses a dry magneto assembly (314) disposed on the right-hand side of the crankshaft (302). The dry magneto assembly (314) is configured to rotate along with the crankshaft (302) to generate power which recharges a battery (not shown). Further, as per an embodiment, a centrifugal fan (not shown) is disposed in front of the magneto assembly (314) forming part of a cooling system to cool the powertrain (101). The centrifugal fan (not shown) rotates along with the crankshaft (302) and draws atmospheric air inside and circulates it throughout the interior portions of the shroud (not shown).

[00028] The clutch member (319) i.e. centrifugal clutch (319) ensures that at low to idle speeds the power transmission from the powertrain (101) is disengaged to the rear wheel (109) (as shown in fig. 1) as spring loaded centrifugal shoe unit (not shown) fixedly attached to the LH crankshaft (302L) and capable of expanding and engaging with a clutch drum (319a) on rotation of the crankshaft (302) beyond a predetermined speed thereby rotating driving gear member (317). The driving gear member (317) is integrally formed with the clutch drum (319a) i.e. welded with the clutch drum (319a). It is contemplated that the driving gear member (317) could be a separate part connected to the clutch drum (319a). On attaining a certain rpm the driving gear member (317) rotates the first driven gear (318) which in turn rotates the rear wheel (109). The engine sprocket (not shown) is disposed outside the cover

(204) which receives rotary motion from the output shaft (315) of the gear train mechanism. The engine sprocket (not shown) is internally splined and mounted on external splines on the end of the output shaft (315) juxtaposing outside the rear portion of the LH crankcase (206L). A chain (not shown) connects the engine sprocket to a corresponding wheel sprocket (not shown) on the rear wheel (109) (as shown in Fig. 1). This way rotary motion is transferred to the rear wheel (109). The final drive to the rear wheel (109) of the two wheeled vehicle is usually a positive drive such as sprocket and chain arrangement but includes other drive means also which is generally known in the art.

[00029] A starter torque actuation device (A) configured to have a lubrication path attached to LH crankcase (206L), said starter torque actuation device (A) comprises a cover (204) configured to have the lubrication path (401, 402), and a actuation shaft

(305) rotatably mounted upon said cover (204) having an end exteriorly accessible from outside of the cover (204). The actuation shaft (305) configured to have a drive gear (306) disposed within said cover (204). As per an embodiment, the drive gear

(306) is a sector type gear having straight teeth (spur type gear). An operating lever

(205) is attached to exteriorly accessible end of the actuation shaft (305). A return biasing member (307) e.g. a torsional spring is provided within the cover (204) which is disposed about said actuation shaft (305). Said return biasing member (307) having an exterior end fixed to the cover (204) and an interior end connected to the drive gear (306) exerting a rewinding force on said actuation shaft (305). An idler shaft (308) disposed parallel to the actuation shaft (305). The idler shaft (308) is configured to have an idler gear (309) which is drivingly connecting the drive gear (306) and a axially movable ratchet gear (310). The ratchet gear (310) axially moveable on driven shaft (311). The driven shaft (311) configured to have the lubrication path (3 I IP). The drive gear (306) is mounted on the actuation shaft (305) which is drivingly connected to the idler gear (309). The idler gear (309) is mounted on the idler shaft (308). In a preferred embodiment, the idler gear (309) is integrated type hybrid gear having spur gear portion (309a) and helical gear portion (309b). The diameter of spur gear portion (309a) is smaller than the helical gear portion (309b) of the idler gear (309). The ratchet gear (310) is provided on the LH crank shaft (302L) and is adapted to transmit torque from the idler gear (309) to a ratchet nut (312). The ratchet gear (310) consists of two parts i.e. gear teeth on one side of an external radial portion and ratchet teeth on other side. As shown, the ratchet gear (310) has a helical gear portion (310a) that defines the receiving portion for receiving a force from helical gear portion (309b) of idler gear (309). The ratchet portion (310b) of ratchet gear (310) engages and rotates the ratchet nut (312) with force transmitted from the idler gear (309) to the ratchet gear (310). The ratchet nut (312) is fixedly mounted on LH crankshaft (302L). The ratchet nut (312) configured to have oil seal member (313) to provide leak proof lubrication from the driven shaft (311) to crankshaft (302) while enabling the starter system or device to run with dry lubrication. As per an aspect of the present subject matter, the word kick starter assembly has been interchangeably used for starter torque actuation device or system or cranking torque actuation device. As per alternate embodiments, the actuation device may run dry or with dry lubrication or with wet lubrication.

[00030] A foot pedal (207) is disposed outwardly operable by the rider manually. The rider places his foot upon foot pedal (207) and applies force on the foot pedal (207) downwardly to initiate kicking operation, to crank the powertrain (101). This action rotates the operating lever (205) which is connected to the exterior end of the actuation shaft (305), hence the force is transmitted from the actuation shaft (305) to drive gear (306). The drive gear (306) is in direct contact with the spur gear portion (309a) of idler gear (309). The helical gear portion (309b) of idler gear (309) being operatively associated with the helical gear portion (310a) of the ratchet gear (310). The ratchet gear (310) configured to have recess or annular groove (310c) provision which acts as receiving portion for guide spring (321). The ratchet gear (310) is adopted to rotate about the axis of driven shaft (311) with a predetermined movement when force is transmitted to the ratchet gear (310). The guide spring (321) is configured to move within guide groove (not shown) where guide spring (321) guided by a guide groove is provided within cover (204). The guide groove (not shown) is integrated with the cover (204) itself as single casted member thereby enabling a laterally compact layout of the power unit. The resistance is produced by guide spring (321) in form of frictionally gripping on recess portion (310c) on ratchet gear (310). The force from idler gear (309) which is in helical - helical teeth meshing with the ratchet gear (310) causes the ratchet gear (310) to rotate which is resisted by guide spring (321). The guide spring (321) resist the rotation of ratchet gear (310) which makes the ratchet gear (310) to move forward, but on further force applied on operating lever (205) by the rider, the ratchet gear (310) rotates on its own axis, as the force applied overcomes the resistance of guide spring (321). Further, the face width of helical gear portion (309b) of the idler gear (309) is larger than the helical gear portion (310a) of the ratchet gear (310). Hence despite of forward movement of the ratchet gear (310) the force is continuously transmitted from helical gear portion (309b) of idler gear (309) to the helical gear portion (310a) of the ratchet gear (310) as both remains in a meshing relationship. Moreover, the rotation of ratchet gear (310) occurs at extreme end of the driven shaft (311) which makes the ratchet gear (310) to engage with the ratchet nut (312) which is having complementary shaped ratchet portion (312a). The ratchet gear (310) compresses the oil seal member (313) which is disposed in the ratchet nut (312). So, when ratchet nut (312) subject to rotational force, it in turn rotates the crankshaft (302) to crank the powertrain (101). On withdrawal of pressure from the foot pedal (207), the return biasing member (307) withdraws the operating lever (205) to starting position. This creates a desirable operating gap between the driven shaft (311) and crankshaft (302) once the torque transfer is completed as an intermittent requirement which however can potentially lead to leak of the lubricant., To eliminate this consequential problem, an oil seal member (313) is disposed between the driven shaft (311) and ratchet nut (312) which ensures continuous & unhindered supply of lubrication after disengagement of the ratchet gear (310) and ratchet nut (312) from the starting drive shaft to the crankshaft area & its peripheral parts. Moreover, gears like drive gear (306), the idler gear (309) becomes stationary after kicking operation, resulting in reduced power consumption leading to low inertia losses for the powertrain. Moreover, the rattling and wining noise is also reduced because of the proposed layout. [00031] Fig. 4 illustrates the cross-sectional perspective view of the powertrain (101) and a transmission assembly according to the embodiment of the present subject matter and a local enlarged view. Referring to Fig. 4 in view of fig. 2 and fig. 3, the cylinder head (202) (as shown in fig. 2) houses various components such as camshafts (405), rocker arms (406) etc. Generally, the cylinder head (202) (as shown in fig. 2) components are synchronized using suitable camshaft transmission assembly which convert the movements of the crankshaft (302) to drive the camshaft (405). The camshaft transmission assembly includes cam chain (409), sprocket (410) which drives the camshaft (405) which in turn actuates at least one pair of rocker arms (406) supported on two rocker shafts respectively. The rocker arms (406) operate a sleeve each for each cylinder bore to open and close the inlet and exhaust apertures using valves (408) to access the common combustion chamber (303) (as shown in fig. 3).

[00032] In the LH crankcase (206L), of horizontally disposed powertrain (101), an oil sump (not shown) is provided for continuous lubrication and cooling, via. The lubrication path, of a piston (not shown) and a plurality of piston cylinder wall and other parts of the powertrain (101). The lubrication and cooling of the piston (301), the plurality of piston cylinder wall and other parts of the powertrain (101) begins once an operation cycle of thermal energy conversion into mechanical energy begins. Once the operation cycle starts, rotation of the crankshaft (302) also starts. On the LH crankshaft (302L), a gear oil pump drive (GOPD) (407) is mounted on crankcase (206) and the gear oil pump drive (GOPD) (407) are mated with an oil pump assembly (not shown). All above-mentioned parts are disposed on the LH crankshaft (302L). Due to rotation of the LH crankshaft (302L), the gear oil pump drive (GOPD) (407) starts rotating, since the gear oil pump drive (GOPD) (407) is in contact with the oil pump assembly (not shown) which results the movement of lubricant oil from sump (not shown) to lubricate and cool the clutch member (319) i.e. centrifugal clutch (319), piston (301), the plurality of piston cylinder wall and other parts of the powertrain (101). An oil reservoir (R) being formed by the cover (204) and the LH crankcase (206L) halves which are mated together. The oil pump (407a) draws the lubricating oil through inlet and into the filter housing, (not shown) where the oil is filtered in the filter housing (not shown) and then drawn into the oil pump (407a) through the pump shaft (not shown). As per an embodiment, the oil can be any lubricant & can also serve the function of being a coolant. Thus the words oil & lubricant are used interchangeably.

[00033] Said lubrication path includes a first distributor passage (401), a second distributor passage (402), a third distributor passage (3 I IP), and fourth distributor passage (302P). The first distributor passage (401) formed within cover (204) to continuously receive oil from the reservoir (R); said first distributor passage (401) extends from reservoir (R) to connect with the second distributor passage (402). Further the second distributor passage (402) receives oil from the first distributor passage (401). The second distributor passage (402) feeds lubricant / oil to the third distributor passage (3 I IP) via cross hole (404). The third distributor passage (3 I IP) is formed within driven shaft (311) which extends from the cross hole (404) to connect with the fourth distributor passage (302P). The fourth distributor passage (302P) is formed within the crankshaft (302) to feed oil to the crankpin. Said fourth distributor passage (302P) includes plurality of holes. The plurality of holes includes at least one ejection hole (404a), at least one injection hole (404b) and at least one oil hole (404c) in radial direction. The no gap situation between crankshaft (302) and driven shaft (311) after kicking operation, is maintained because of oil seal member (313). As per an embodiment, the Oil seal member (313) is subjected to partial desirable compression during kicking operation. The oil is ejected from the ejection holes (404a) to the centrifugal clutch (319). The oil is purified through clutch member (319) i.e. centrifugal clutch (319) member as it works like centrifugal separator. The blur or dirt particles are accumulated on one side of centrifugal clutch (319). The purified oil thereafter flows into crankshaft (302) through injection holes (404b), where the oil is fed to the crank pin to cool the piston (301), piston rings (403) etc. In the lubrication path an oil hole (404c) is provided to lubricate a bearing / bush (320). The centrifugal clutch (319) is disengaged when the powertrain (101) is running at idle speed such that the crankshaft (302) does not rotate at engine idle. When the engine speed is increased to a predetermined speed, the centrifugal clutch (319) engages to drive the crankshaft (302). The clutch drum (319a) is disposed over the inner rotor and is supported on the crankshaft (302) by bearings. With an increase in the engine speed, a corresponding centrifugal force of the centrifugal weights eventually bend the centrifugal weights outward until they frictionally engage the clutch drum (319a) and is connected to the powertrain (101). The driving gear member (317) is operatively connected to driven gear (318). Therefore, for centrifugal clutch (319), the clearance between the centrifugal weights i.e. series of stacked disks and the clutch drum (319a) determines the engine speed at which the centrifugal weights engage the clutch drum (319a) and allows the powertrain (101) to reach sufficiently high speed (and therefore power) before the centrifugal clutch (319) engages. In a typical centrifugal clutch (319), at low rpm only a small portion of the centrifugal weights touches the clutch drum (319a) and the torque transmitted is small. As a result, the centrifugal clutch (319) may slip over a wide range, typically between 2,500 and 6,500 rpm in an embodiment. The slipping range of the centrifugal clutch (319) is very important as the centrifugal clutch (319) is in the slipping mode frequently in slow corners or at the start of the vehicle (100). A broad slipping range results in loss of engine power in heat, excessive clutch wear and less efficient acceleration. This heat generation leads to more temperature inside the crankcase (206) which further leads to less durability of parts. Hence the lubrication path (401, 402, 3 I IP, 302P) ensures lubrication to bush (320) and crankshaft (302) mounted zone.

[00034] Further the continuous and leak proof as well as clean lubrication is assured because of seal member which is disposed between the driven shaft (311) and ratchet nut (312).

[00035] In addition, the present subject matter assures the shorter path for lubrication because the lubrication path (401, 402, 3 I IP, 302P) is positioned in proximity to the oil sump (not shown).

[00036] 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 302P- Fourth distribution passage

A - Cranking torque actuation 303 -Combustion chamber device/ kick starter assembly/starter 304 - Connecting rod

torque actuation device or system 35 305- Actuation shaft

F - Front portion 306- Drive gear

R - Rear portion 307 -Return biasing member

100 -Vehicle 308- Idler shaft

101 -Powertrain/engine 309- Idler gear

102 - Frame assembly 40 309a -Spur gear portion

103 - Head tube 309b -Helical gear portion

105 - Handle bar assembly 310- Ratchet gear

104 - Front wheel 310a -Helical gear portion

106 - Front suspension(s) 310b- Ratchet portion

107 - Front fender 45 310c - Recess

108 - Swing arm 311- Driven shaft

109 - Rear wheel 31 IP -Third distribution passage

110 - Rear suspension(s) 312 -Ratchet nut

111 - Rear fender 312a -Ratchet portion

112 - Seat assembly (112A, 112B) 50 312b- Nut portion

113 - Centre stand 313 -Oil seal member

114 - Step-through portion 314- Dry magneto clutch

115- Fuel tank 315 -Output shaft

201 - Cylinder head cover 316- Roller bearing

202 - Cylinder head 55 317 -Driving gear member

203 - Cylinder block 318 -First driven gear

204 - Cover 319 -Centrifugal clutch/Clutch

205 - Operating lever member

206 - Crankcase 319a -Clutch drum

207 - Foot pedal 60 320 -Bush

301 -Piston 321 -Guide spring

302- Crankshaft 401- First distributor passage 402- Second distributor passage 700 - Crankshaft

403 -Piston ring 15 701 - Actuation shaft

404 -Cross holes 702 -Return spring 404a - Ejection holes 703 -Ratchet mechanism 404b -Injection holes 703a- Ratchet

404c -Oil hole 703b -Ratchet starter gear

405- Cam shaft 20 704- Idler gear

406- Rocker arms 705 -Gear pump oil drive

407 -Gear oil pump drive (GOPD) 706- Drive shaft

407a -Oil pump 707 -Kick lever

408- Valves 708 -Dry magneto 409 -Cam chain 25 709- Wet clutch

410- Sprocket

Claims

We Claim:

1. A powertrain (101) having a crankcase (206) enclosing a transmission assembly; said transmission assembly comprising: a crankshaft (302), said crankshaft (302) extends substantially rightward and leftward in the powertrain (101) width direction, and a clutch member (319), said clutch member (319) installed on the crankshaft (302); and a starter torque actuation device (A), said starter torque actuation device(A) configured to have a lubrication path connected to the crankcase (206), said starter torque actuation device (A) comprising: at least one driven shaft (311) configured to have the lubrication path, said driven shaft (311) rotatably mounted within a cover (204) of starter torque actuation device (A), at least one axially movable ratchet gear (310), said ratchet gear

(310) mounted on said driven shaft (311), at least one ratchet nut (312), said ratchet nut (312) mounted on the crankshaft (302), at least one oil seal member (313), said oil seal member disposed between the ratchet nut (312) and the driven shaft

(311), and at least one idler gear (309) drivingly connecting a drive gear (306) and the ratchet gear (310), the ratchet gear (310) is adopted to rotate about a longitudinal axis of driven shaft (311) with a predetermined movement to engage with a complementary shaped ratchet portion (312a) of the ratchet nut (312) & the two shafts are separated by a predetermined distance.

2. The powertrain (101) as claimed in claim 1, wherein said driven shaft (311) is coaxial to the crankshaft (302). 3. The powertrain (101) as claimed in claim 1, wherein the cranking torque actuation device (A) includes an actuation shaft (305), said actuation shaft (305) being rotatably mounted within the cover (204), said actuation shaft (305) having an end exteriorly accessible from outside of the cover (204), the end exteriorly accessible supports an operating lever (205).

4. The powertrain (101) as claimed in claim 3, wherein the actuation shaft (305) supports a return biasing member (307) such that the return biasing member (307) being disposed about the actuation shaft (305), said return biasing member (307) having an exterior end fixed to the cover (204) and an interior end connected to the actuation shaft (305) exerting a rewinding force on the actuation shaft (305).

5. The powertrain (101) as claimed in claim 1, wherein said idler gear (309) installed on an idler shaft (308), said idler shaft (308) disposed parallel to the actuation shaft (305).

6. The powertrain (101) as claimed in claim 1, wherein ratchet gear (310) axially movable on the driven shaft (311) configured to have a helical gear portion (310a) and a ratchet portion (310b).

7. The powertrain (101) as claimed in claim 1, wherein said ratchet gear (310) configured to have recess or annular groove (310c) provision which acts as receiving portion for a guide spring (321). 8. The powertrain (101) as claimed in claim 1, wherein said ratchet nut (312) fixedly mounted on the crankshaft (302), said ratchet nut (312) comprises a nut portion (312b), and a ratchet portion (312a) having engagement teeth. 9. The powertrain (101) as claimed in claim 1, wherein said ratchet gear (310) moves axially to rotate the ratchet nut (312) during starting operation such that the ratchet portion (310b) of the ratchet gear (310) engage directly with the complementary shaped ratchet portion (312a) of axially fixed ratchet nut (312).

10. A powertrain (101) having a crankcase (206) enclosing a transmission assembly; said transmission assembly comprising: a crankshaft (302), said crankshaft (302) extends rightward and leftward in the powertrain (101) width direction, and a clutch member (319), said clutch member (319) installed on the crankshaft (302); and a cranking torque actuation device (A), said cranking torque actuation device (A) configured to have a lubrication path connected to the crankcase (206), said cranking torque actuation device (A) includes a lubrication path, said lubrication path is configured to allow smooth & continuous flow of lubrication from a supply side pump to the crankshaft & its peripheral areas.

11. The powertrain (101) as claimed in claim 10, wherein said lubrication path includes a first distributor passage (401), a second distributor passage (402), a third distributor passage (3 I IP), and a fourth distributor passage (302P).

12. The powertrain (101) as claimed in claim 11, wherein said first distributor passage (401) being formed within a cover (204) of the cranking torque actuation device (A) to receive oil from a reservoir (R), said first distributor passage (401) extends from the reservoir (R) to connect with the second distributor passage (402).

13. The powertrain (101) as claimed in claim 11, wherein said second distributor passage (402) formed within the cover (204) to receive oil from the first distributor passage (401), said second distributor passage (402) feed oil to the third distributor passage (31 IP) via a cross hole (404).

14. The powertrain (101) as claimed in claim 11, wherein the third distributor passage (3 I IP) is formed within a driven shaft (311) of the cranking torque actuation device (A), said third distributor passage (3 I IP) extends from the cross hole (404) to connect with the fourth distributor passage (302P).

15. The powertrain (101) as claimed in claim 11, wherein fourth distributor passage (302P) is formed with the crankshaft (302) to feed oil to a crankpin (not shown), said fourth distributor passage (302P) includes a plurality of holes.

16. The powertrain (101) as claimed in claim 15, wherein plurality of holes includes at least one ejection hole (404a), at least one injection hole (404b), and at least one oil hole (404c).

17. The powertrain (101) as claimed in claim 16, wherein said at least one ejection hole (404a) is formed within the crankshaft (302) in radial direction, said ejection hole (404a) ejects to a clutch member (319) of the transmission assembly for oil purification.

18. The powertrain (101) as claimed in claim 16, wherein said at least one injecting hole (404b) formed within crankshaft (302) in radial direction, wherein said injection holes (404b) introduces purified at least one of a lubricant or coolant to the crankshaft (302) from clutch member (319).

19. The powertrain (101) as claimed in claim 16, wherein said at least one oil hole (404c) is formed within crankshaft (302) in radial direction, said oil hole (404c) feeds lubricant to a bush (320) connected to the clutch member (319).

20. A cranking torque actuation device (A) configured to have a lubrication path comprising: a cover (204), an actuation shaft (305), said actuation shaft (305) configured to have a drive gear (306) disposed within said cover (204), an operating lever (205) coupled with actuation shaft (305) a return biasing member (307), said return biasing member (307) being disposed about the actuation shaft (305), an idler shaft (308), said idler shaft (308) configured to have an idler gear (309), said idler gear (309) drivingly connecting the drive gear (306) and a axially movable ratchet gear (310), said ratchet gear (310) installed on a driven shaft (311), and a ratchet nut (312) including a ratchet portion (312a), wherein said ratchet portion (312a) of ratchet nut (312) configured to have an oil seal member (313) configured to circumscribe & form an enclosure sealing the area around the predetermined gap formed between the two parts.

21. The cranking torque actuation device (A) as claimed in claim 20, wherein said cover (204) is configured to have the lubrication path, lubrication path includes a first distributor passage (401), a second distributor passage (402) formed within the cover (204), a third distributor passage (3 I IP) formed within the driven shaft (311), and a fourth distributor passage (302P) with the crankshaft (302) of an powertrain (101).

22. The cranking torque actuation device (A) as claimed in claim 20, wherein said actuation shaft (305) is rotatably mounted on said cover (204) having an end exteriorly accessible from outside of said cover (204), coupled with said operating lever.

23. The cranking torque actuation device (A) as claimed in claim 20, wherein said return biasing member (307) includes an exterior end fixed to said cover (204) and an interior end connected to said actuation shaft (305) exerting a rewinding force on said actuation shaft (305).

24. The cranking torque actuation device (A) as claimed in claim 20, wherein said idler shaft (308) is disposed parallel to the actuation shaft (305). 25. The cranking torque actuation device (A) as claimed in claim 20, wherein said ratchet gear (310) comprises a helical gear portion (310a) and a ratchet portion (310b).

26. The cranking torque actuation device (A) as claimed in claim 20, wherein said ratchet nut (312) axially fixedly mounted on crankshaft (302) comprises a nut portion (312b) and a ratchet portion (312a).

27. The cranking torque actuation device (A) as claimed in claim 20, wherein said ratchet portion (310b) of the ratchet gear (310) is engaged with ratchet portion (312a) of ratchet nut (312).