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EP-4232726-B1 - A POWER TRANSMISSION LAYOUT FOR A SADDLE TYPE VEHICLE

EP4232726B1EP 4232726 B1EP4232726 B1EP 4232726B1EP-4232726-B1

Inventors

  • SHASHANKA, P Gajjarahalli
  • P, Kumaresan
  • SUMITH, JOSEPH
  • MOHAN, Umate

Dates

Publication Date
20260506
Application Date
20211020

Claims (11)

  1. A power transmission system (111) for a saddle type vehicle (100), the power transmission system (111) comprising: a transmission unit (113) comprising an outer casing (132) disposed aligned to a crankcase (120); wherein the outer casing (132) is configured with a plurality of covers (133, 134) detachably attached to form the outer casing (132), and the plurality of covers (133, 134) comprising a first cover (133), and a second cover (134), the first cover (133) being configured to cover one or more components of the transmission unit (113) and the second cover (134) being configured to mount a kick starter assembly (135), wherein the first cover (133) comprising a mounting space (136) to accommodate the second cover (134), an inner surface (138) of the first cover (133) comprising a laterally inward extending projection (137) surrounding the mounting space (138), the inward extending projection (137) comprising one or more mounting means (139) facilitating mounting of the second cover (134) with the first cover (133), and wherein the second cover (134) is adapted to receive a direct force from the kick starter assembly generated during kick starting, (133) , characterized in that the first cover (133) is made up of a resin material, and the second cover (134) is made up of metal, the second cover (134) adapted to transfer a resultant force on the first cover (133).
  2. The power transmission system (111), as claimed in claim 1, wherein the power transmission system comprising an engine (112) configured to generate power for traction, at least a portion of the engine (112) being disposed in a crankcase (120); and the kick starter assembly being coupled to the at least a portion of the engine (112) disposed in the crankcase (120).
  3. The power transmission system (111), as claimed in claim 1, wherein the first cover (133) comprises an outer periphery wall (147), the outer periphery wall (147) comprising: a first portion (147a) and a second portion (147b) configured to overlap to leave a space in between defining at least one air passage (148) formed at-least at one location, wherein the at least one air passage (148) being configured to facilitate air flow within the transmission unit (113) and, wherein at least a corresponding portion aligned to the at least one air passage (148) being formed on the crankcase (120) to increase a lateral width for increased air circulation.
  4. The power transmission system (111), as claimed in claim 1, wherein the first cover (133) and the second cover (134) comprising co-axially aligned openings (141a, 141b), co-axially aligned with a kickstarting drive means (144) of the kick starter assembly (135) which passes through both the openings (141a, 141b) and gets connected with a kick start lever (142) for facilitating user operation.
  5. The power transmission system (111), as claimed in claim 4, wherein the opening (141a) being provided on the second cover (134), the opening (141a) being configured to accommodate one end of the kick starter lever (142).
  6. The power transmission system (111), as claimed in claim 4, wherein the second cover (134) comprising a first housing space (143) to house the kickstarting drive means (144), and a second housing space (145) to house a kickstarting driven means (146).
  7. The power transmission system (111), as claimed in claim 6, wherein the kickstarting driven means (146) being coupled to at least a portion of a crankshaft of the engine (112), and a central axis (ZZ') of the kickstarting driven means (146) being coaxial and parallel to an axis of the crankshaft (CC'); and, wherein torque generated during kickstarted being transferred from the central axis (Z-Z') of the kickstarting driven means (146) to the central axis (C-C') of the crankshaft (124) such that a reaction torque being transferred to the second cover (134) facilitating elimination of direct stress transfer on the first cover (133).
  8. The power transmission system (111), as claimed in claim 1, wherein the transmission unit (113) comprises a resin drain pipe (149) configured to facilitate one-way flow of the water accumulated in the transmission unit (113).
  9. The power transmission system (111) as claimed in claim 1, the power transmission system (111) comprising an engine (112), and a transmission unit (113); the engine (112) comprising: a crankcase (120); an integrated starter-generator (125); an oil pump (150); and an oil pump cover (151); wherein the integrated starter-generator (125) being mounted directly on at least a portion of the crankcase (120), the integrated starter-generator (125) being disposed on an opposite side of the transmission unit (113), the oil pump (150) being mounted on the same side of the integrated starter-generator (125), and the oil pump cover (151) being configured to cover the oil pump (150) exclusively.
  10. The power transmission system (111), as claimed in claim 9, wherein one end (117) of a breather hose (116) being connected to an air cleaner (115) and an other end (118) of the breather hose (116) being attached on a cylinder head cover (119) of the engine (112).
  11. The power transmission unit (111), as claimed in claim 9, wherein a fan housing (127) being disposed directly on at least a part of the crankcase (120) in proximity of the integrated starter-generator (125).

Description

TECHNICAL FIELD The present invention relates generally to a saddle type vehicle and more particularly, to a power transmission layout for the saddle type vehicle BACKGROUND Generally, in saddle type vehicles, IC engines are used as a power source and the generated power is transferred to a rear wheel for traction through a transmission system. The transmission unit includes a plurality of components to connect a crankshaft of the IC engine to the wheel and transmits power by changing the ratio between the crankshaft rotational speed and the rotational speed of a wheel to provide speed as well as torque conversions of the saddle type vehicles. Regular geared transmission system requires rider of the saddle type vehicles to manually perform gearshifts. Whereas, CVT based transmission systems eliminates the need of performing manual gearshifts by providing automatic change in gear ratios between the crankshaft rotational speed and the rotational speed of the wheel. The CVT system comprises a front pulley operably attached to the crankshaft housed in a crankcase, a rear pulley operably connected to the wheel and a belt rests between them, all of which are enclosed within a crankcase of the IC engine. The front pulley comprises a variator mechanism and the rear pulley comprises a centrifugal clutch. Different gear ratios are obtained by changing the effective diameter of the front pulley and the rear pulley while the belt is engaged on the front pully and the rear pully. In the saddle type vehicle layouts, the CVT system is disposed on effectively one side of the saddle type vehicles, mainly on left hand side, an exhaust system on right hand side, and the IC engine is disposed between the CVT system and the exhaust system. In such layout when the CVT system is disposed adjacent to the crankcase housing the crankshaft, the left-hand side of the system becomes bulky. For overall vehicle balance and dynamic stability in the saddle type two-wheeler, wherein the crankcase also acts as a swing arm, and is surmounted by the rear wheel, the center of gravity point of the engine needs to lie on or near to the Rear wheel's center plane disposed perpendicular to the axis of wheel rotation. However, generally in the scooter engines surmounted by the rear wheel, the engine's mass distribution is more skewed towards one side of the vehicle due to placement of crankcase, and CVT system on the same side. Engine is one of the major contributors to the vehicle in terms of the overall vehicle weight. Hence, achieving the engine mass distribution to be more centred towards the rear wheel center plane becomes important from vehicle's "Body balance" perspective. Also, when redistributing the engine parts' location to achieve the balance between the vehicle RH side and LH side, the overall width of the engine is difficult to be contained within narrow limits. JP H03 271090 A discloses the preamble of claim 1. BRIEF DESCRIPTION OF THE DRAWINGS The detailed description is described with reference to a saddle type saddle type vehicle along with the accompanying figures. The same numbers are used throughout the drawings to reference like features and components. Fig. 1 illustrates the side view of a saddle type vehicle employing an embodiment of the present subject matter.Fig. 2 illustrates a top view of the power transmission system with the air intake structure according to the embodiment of the present subject matter.Fig. 3a, and 3b illustrates a top cut section of the engine and the transmission unit of the power transmission unit according to the embodiment of the present subject matter.Fig. 4 illustrates an exploded view of an outer casing of the transmission unit according to the embodiment of the present subject matter. DETAILED DESCRIPTION In current times automobile customers are demanding high efficiency, compact and lighter vehicle and appealing visual requirement, which has increased the competition in automotive sector. In addition, with growing environmental concern, emission requirements are getting more and more stringent. Due to mentioned requirements, new technologies and mechanisms are being explored constantly. Generally, heavier the vehicle is, more energy it needs for traction and results in lower efficiency. Heavier vehicles have greater inertia and greater rolling resistance, both of which contribute to an increased fuel consumption. Further, reducing vehicle weight is a very effective way to improve a vehicle's efficiency. Vehicle weight and engine power are two of the most important parameters that influence a vehicle's fuel consumption and carbon dioxide emissions. Weight reduction of the vehicle, yields benefit in fuel economy by virtue of reduction in load carried by the vehicle. Generally, known arts are achieving weight reduction by substituting lighter materials, such as aluminum and advanced composites, as well as making vehicle design changes. However, the use of lighter materials poses issues such as d