DESC:TECHNICAL FIELD
[0001] The present subject matter relates generally to an engine assembly of a two-wheeled vehicle and more particularly but not exclusively, to a crankshaft assembly for the engine assembly of the two-wheeled vehicle.
BACKGROUND
[0002] A two-wheeled vehicle is powered by an internal combustion engine comprising a crankshaft assembly rotatably supported by a crankcase assembly. Generally, an internal combustion engine for a two-wheeled vehicle includes a crankcase assembly divided into two crankcase halves, a crank chamber being defined and formed by the crankcase halves, a crankshaft housed in the crank chamber and a cylinder block connected to the crankcase. A crankshaft is rotatably attached on a crankcase through a pair of rotary bearings each disposed on a LH and a RH crankcase, a piston slidable in a cylinder bore is connected to a crank pin of the crankshaft through a connecting rod. The crankcase houses the crankshaft assembly, clutch assembly, starter assembly and gearbox assembly and other ancillary systems, which include lubrication system, cooling system and exhaust system, all housed in the main engine body. The crankcase is made of know metals like aluminium.
[0003] The crankcase assembly further includes a sump containing fluid essential for lubrication of movable parts inside the internal combustion engine, and for cooling of the different parts of the engine. Further, the crankshaft assembly comprises one or more sealing members to prevent oil from entering into particular regions inside the engine. The crankshaft assembly includes a crankshaft comprising one or more sealing members disposed around it. The one or more sealing members used are generally stationary members. However, a movable sealing member capable of rotating along with the rotating crankshaft is also in use.

BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The detailed description of an air filter assembly of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.
[0005] FIG. 1 shows a perspective view of an internal combustion engine according to an embodiment of the present invention.
[0006] Fig. 2 illustrates a sectional view of the engine assembly taken along ab and xy axis as shown in Fig. 1.
[0007] Fig. 3 illustrates a detailed view of the encircled portion of the engine assembly as shown in Fig. 2.
[0008] Fig. 4 illustrates a crankshaft assembly according to an embodiment of the proposed invention.
[0009] Fig. 5a illustrates a perspective view of a sprocket member according to an embodiment of the present invention.
[00010] Fig. 5b illustrates a top view of the sprocket member.
[00011] Fig. 5c illustrates a sectional view of the sprocket member according to an embodiment of the present intention.
[00012] Fig. 6a illustrates a perspective view of at least one sealing member according to an embodiment of the present invention.
[00013] Fig. 6b illustrates a sectional view of the at least one sealing member taken along pq axis as shown in Fig. 6a.
DETAILED DESCRIPTION
[00014] Generally, a conventional two wheeled vehicle is powered by an internal combustion engine disposed at a lower half of the vehicle. The engine converts chemical energy into mechanical energy by combustion of air-fuel mixture within a combustion chamber of the engine. The engine, among other components, has a cylinder comprising a cylinder head atop or in front of the cylinder and receiving a reciprocating piston from the bottom or the rear. On combustion of the air-fuel mixture, the piston transfers the energy generated during combustion to a crankshaft through a connecting rod thereby driving the crankshaft. In this way, the reciprocatory motion of the piston is converted to rotatory motion of the crankshaft. The crankshaft is housed inside a crankcase beneath or behind the cylinder block. In order to set the vehicle into motion, the power supplied to the crankshaft of the internal combustion engine is carried to a wheel of the vehicle, in a controllable way, through a transmission system. The transmission system in the conventional vehicle employs a clutch and a gearbox with plurality of gears, wherein gear shift is achieved manually which enables gears to be selected only in an ascending or descending sequence. A gear-less transmission system, called a continuously variable transmission system, is also known where the gearshift is achieved by centrifugal forces.
[00015] Conventionally, the internal combustion engines are provided with an engine lubrication channel that enables lubrication of the moving engine components during engine operation. The lubrication channel involves transmission of oil through a particular channel for achieving the desired lubrication and cooling of the engine components. The lubrication oil functions as a lubricating agent and a cooling agent in an internal combustion engine. The oil used for this purpose may be stored in an oil sump, which also acts as a repository for the oil expelled from the engine components as a result of their working. The oil pump is utilized to draw and deliver the lubrication oil to desired locations within the engine for lubrication and cooling purposes under low, medium or high engine speed conditions. The circulating lubrication oil reduces the wear and tear of the engine components and also ensures that the engine is consistently maintained under optimal temperatures and thereby enhancing engine performance, life of engine components, and the service intervals of the lubricants.
[00016] Conventionally, the oil sump is formed within a crankcase assembly. The lubrication oil is carried from the oil sump to a right casing of the crankcase assembly through a left casing. The lubrication oil is prevented from entering into unwanted areas by incorporating one or more sealing members that prevent oil from entering into particular regions. For example, it is not desirable to have oil entry into the region containing plurality of rollers in a movable drive.
[00017] Further, the oil may leak out of the crankcase and may be visible to the user, which is generally not desirable. The oil leakage is again prevented by the one or more sealing members.
[00018] Generally, one or more sealing members, being oil seals are placed inside the engine assembly to prevent leakage of oil or movement of oil into particular regions inside the engine assembly. Further, the oil seal is disposed in close proximity to the crankshaft assembly; particularly the one or more oil seals are disposed around the crankshaft of the crankshaft assembly. Generally, a movable member or a fixedly attached member is disposed in between the one or more oil seals and the crankshaft assembly. The movable member or the fixedly attached member is capable of substantially supporting the one or more oil seals.
[00019] The fixedly attached member is configured to rotate along with the crankshaft of the crankshaft assembly. Whereas, the one or more oil seals are generally stationary members. During higher engine speeds, the rotating stationary member gets worn off due to constant friction with the one or more oil seals. A well-defined annular ring is formed on an outer diametrical surface of the stationary member. The annular ring may become bigger upon further usage of the crankshaft assembly. The annular ring formed creates a gap between the rotating stationary member and the one or more oil seals. The gap so formed serves as a disadvantage by allowing the oil to leak outside of the oil seal. The leaked oil affects the efficiency of other associated parts and other parts inside the engine assembly. Further, the engine assembly may require frequent servicing due to loss of oil inside the engine assembly.
[00020] Furthermore, it is not desirable to have the oil seals with a bigger inner diameter and a bigger outer diameter. The leakage of oil is greater with greater diameter of the oil seal. Hence, one or more oil seals disposed on an another member on the crankshaft have bigger diameters as compared to the oil seals disposed on the crankshaft without any intermediary member.
[00021] According to an embodiment of the present invention, the intermediary members upon which the one or more oil seals rest or come in contact with are eliminated. Instead, the one or more oil seals are disposed on the crankshaft assembly such that the inner diametrical surface of the one or more oil seals is in contact with the crankshaft of the crankshaft assembly. Thereby reducing the number of parts in the crankshaft assembly resulting in reduction of the cost of the engine assembly. Furthermore, the serviceability and durability of the engine assembly is increased because of reduction of number of parts inside the engine assembly.
[00022] Furthermore, according to an embodiment of the present invention, the one or more oil seals are configured to be accommodated on the crankshaft of the crankshaft assembly. Such an oil seal which is disposed such that it comes in contact with the crankshaft has a small diameter compared to a conventional oil seal. The small diameter of the oil seal accounts to reduced friction between the crankshaft and the inner diameter of the crankshaft, this helps in reducing the leakage of oil through it. Therefore, according to the present invention, the leakage of oil through the oil seal as in the conventional crankshaft assembly is substantially reduced by controlling the diameter of the oil seal.
[00023] Furthermore, due to elimination of intermediary parts that exist between the one or more oil seal and the crankshaft, friction between the oil seal and the member coming in contact with the oil seal is substantially prevented. Therefore, durability of the oil seal as well as the crankshaft assembly is increased and a more reliable and durable engine assembly is achieved.
[00024] Furthermore, according to an embodiment, since the intermediary parts between the oil seal and the crankshaft is eliminated, the crankshaft of the crankshaft assembly does not involve any supporting portions to support the intermediary members. Therefore, without supporting portions, the stress received by the crankshaft is reduced and a stiffer and stable crankshaft assembly is achieved and the efficiency of the engine assembly is achieved.
[00025] Furthermore, according to an embodiment of the present invention, the crankshaft assembly is rotatably supported inside the crankcase assembly by a pair of bearing assembly. A cam chain is disposed inside the engine assembly and is disposed in close proximity to the bearing assembly. The cam chain is supported by a toothed member. The toothed member for example, is a sprocket member. The sprocket member is also disposed in close proximity to a ball bearing assembly of the pair of ball bearings. According to an embodiment of the present invention, the sprocket member includes a shoulder portion capable of abutting against the ball bearing assembly. Furthermore, according to an embodiment of the present invention, the sprocket member is disposed posterior to the oil seal when viewed from left side of the engine.
[00026] According to an embodiment of the present invention, the crankshaft includes one or more accommodating portions to accommodate the ball bearing assembly and the rollers of the movable drive. The first accommodating portion and the second accommodating portion include a well-defined gap there between capable of accommodating the oil seal and the sprocket member. The well-defined gap between the first accommodating portion and the second accommodating portion does not involve any irregular surfaces, in other words, the crankshaft portion in the well-defined gap is stiff and is more reliable.
[00027] According to an embodiment of the present invention, the one or more oil seals include a number of deflecting portions. The deflecting portions are aligned in any of one direction. The deflecting portions allow the flow of oil in one direction only.
[00028] According to an embodiment of the present invention, the one or more oil seals include at least one axial ridge.
[00029] These and other advantages of the present subject matter would be described in greater detail in conjunction with the figures in the following description.
[00030] FIG. 1 shows a perspective view of an internal combustion engine assembly 100 according to an embodiment of the present invention. The engine assembly 100 comprises a cylinder assembly 101 and a crankcase assembly 102, the engine assembly 100 rotatably supports a rear wheel of a vehicle. The rear portion of the crankcase assembly 102 includes a power transmission system 105 comprising a continuously variable transmission made by using a belt and a pulley. The engine assembly 100 includes an air cleaner mounted on the upper surface side of the crankcase assembly 102 positioned on the rear side of the engine assembly 100. Further, the crankcase assembly 102 is covered by a variator cover 104 which seals the crankcase assembly 102 from the left side and supports the components of the continuously variable transmission. During operation of the engine assembly 100, the components of the power transmission system 105 become hot and hence are air cooled. The air enters the crankcase assembly 102 from a front portion of the left side thereof through an inlet tube 103. The variator cover 104 comprises of an opening (not shown) for receiving the incoming air.
[00031] Fig. 2 illustrates a sectional view of the engine assembly taken along ab and xy axis as shown in Fig. 1. The engine assembly 100 includes a crankshaft assembly 201 housed and rotatably supported by the crankcase assembly 102. In particular, the crankshaft assembly 201 is rotatably supported by a pair of bearing assembly 202 disposed around at least a portion of the crankshaft assembly 201 and inside the crankcase assembly 102. The crankshaft assembly 201 includes a pair of laterally extending arms 201a, 201b, the pair of laterally extending arms 201a, 201b including a RH arm 201a and a LH arm 201b extending laterally from a connecting rod (not shown). The pair of bearing assembly 202 is disposed on either side of the connecting rod to rotatably support the pair of laterally extending arms 201a, 201b. Further, a covering member 203 is disposed around the LH arm 201b. A cam chain 209 is disposed posterior to the covering member 203. Hence, by accessing the covering member 203, the cam chain 209 can be accessed.
[00032] According to an embodiment of the present invention, the covering member 203 is configured to be detachably attachable. The covering member 203 according to the present invention enables easier and quicker access to the cam chain 209 during servicing conditions. The encircled portion in the figure illustrates a part of the crankshaft assembly 201 supporting one or more sealing members according to the present invention.
[00033] Fig. 3 illustrates a detailed view of the encircled portion of the engine assembly as shown in Fig. 2. The encircled portion depicts a LH arm 201b capable of accommodating the proposed invention. The LH arm 201b includes one or more accommodating portions 201ba and 201bb capable of accommodating a movable drive 204 and a LH bearing assembly 202a of the pair of bearing assembly 202. The one or more accommodating portions 201ba and 201bb include a first accommodating portion 201ba disposed anterior to the covering member 203. The first accommodating portion 201ba is capable of accommodating the movable drive 204. Further, the one or more accommodating portions 201ba and 201bb include the second accommodating portion 201bb capable of supporting the LH bearing assembly 202a of the pair of bearing assembly 202. Further, the LH arm 201b does not include any accommodating portions in between the first accommodating portion 201ba and the second accommodating portion 201bb. Further, there is no stress experienced by that portion of the crankshaft assembly 201 due to absence of members that are to be accommodated. This makes the surface of the LH arm 201b between the first accommodating portion 201ba and the second accommodating portion 201bb uniform and stiffer. Therefore, a stable operation of the crankshaft assembly 201 is achieved.
[00034] Further, according to an embodiment of the present invention, the first accommodating portion 201ba and the second accommodating portion 201bb includes a well-defined gap 201bc there between. Furthermore, an at least one sealing member 206 and a sprocket member 205 are disposed in the well-defined gap 201bc. The at least one sealing member 206 is capable of being seated on the LH arm 201b of the crankshaft assembly 201. The sprocket member 205 is disposed posterior to the at least one sealing member 206. An inner diametrical surface of the at least one sealing member 206 is configured to have a contact with an outer diametrical surface of the LH arm 201b. The at least one sealing member 206 is supported by the inner diametrical surface of the covering member 203. Further, the sprocket member 205 is capable of abutting against the LH bearing assembly 202a of the pair of bearing assembly 202 (not shown).
[00035] According to an embodiment of the present invention, the first accommodating portion 201ba includes a first diameter ?1 of approximately 17mm, the second accommodating portion 201bb includes a second diameter ?2 of approximately 23mm, and the well-defined space 201bc includes a third diameter ?3 of approximately 6mm.
[00036] Fig. 4 illustrates a crankshaft assembly according to an embodiment of the proposed invention. The crankshaft assembly 201 includes a RH arm 201a and the LH arm 201b each extending laterally from a piston rod 207. The crankshaft assembly 201 is configured to accommodate the movable drive 204, the at least one sealing member 206, the sprocket member 205 and the pair of bearing assembly 202. The crankshaft assembly 201 being a rotatable structure is configured to support the at least one sealing member 206. The at least one sealing member is stationary with respect to the rotating LH arm 201b. Further, the well-defined gap 201bc is configured to accommodate the at least one sealing member 206 and the sprocket member 205. Since, the inner diametrical surface of the at least one sealing member 206 is in direct contact with the outer diametrical surface of the LH arm 201b, the diameter of the at least one sealing member 206 is smaller and the smaller surface area has resulted in reduced friction between the at least one sealing member 206 and the LH arm 201b. Further, the movable drive 204 is supported by a movable-drive plate 204a disposed on the crankshaft assembly 201. In order to prevent the breakage of the crankshaft assembly 201 due to the load exerted by the movable-drive plate 204a, the crankshaft assembly 201 is configured with an angular portion R1 to appropriately accommodate the movable-drive plate 204a. The angular portion R1 is provided to prevent sharp edges on the crankshaft assembly 201, because the sharp edges are more prone to breakage. According to an embodiment of the present invention, the angular portion has a radius of approximately in the range of 0.5-0.8mm.
[00037] Further, the sprocket member 205 is capable of abutting against the LH bearing assembly 202a.
[00038] Fig. 5a illustrates a perspective view of a sprocket member according to an embodiment of the present invention. The sprocket member 205 comprises a shoulder portion 205a disposed at a peripheral surface of the sprocket member 205. Further, the sprocket member 205 comprises a plurality of toothed members 205b capable of getting engaged with accommodating portions of the cam chain. In other words, in particular, the cam chain is supported on the plurality of toothed members 205b of the sprocket member 205. Furthermore, the shoulder portion 205a is configured to abut against the LH bearing assembly 202a. The shoulder portion 205a enables proper support to the sprocket member 205 for stable operation of the sprocket member 205.
[00039] Fig. 5b illustrates a top view of the sprocket member. It is evident from the figure that the plurality of toothed members 205b extends radially outwardly from another periphery 205p and defining a gap between two adjacent teeth.
[00040] Fig. 5c illustrates a sectional view of the sprocket member according to an embodiment of the present intention. The shoulder portion 205a extends annularly in one periphery 205o. The diameter of the shoulder portion 205a is lesser than the outer diameter of the plurality of toothed members 205b. This distinction in the diameter ensures that the cam chain (not shown) is never allowed to interfere with the shoulder portion 205a of the sprocket member 205, thereby protecting the stable operation of the sprocket member 205.
[00041] Fig. 6a illustrates a perspective view of an at least one sealing member according to an embodiment of the present invention. The at least one sealing member 206 includes an axial ridge 206a for having a desired contact surface with the outer diametrical surface of the crankshaft assembly (not shown). Fig. 6b illustrates a sectional view of the at least one sealing member taken along pq axis as shown in Fig. 6a. The at least one sealing member 206 includes a plurality of deflecting portions 206b. The plurality of deflecting portions 206b prevents minute particles of oil from entering into particular regions of the engine assembly. Further, the plurality of deflecting portions 206b are aligned in one particular direction only, so that, the oil particles are streamlined in one single direction only and are not allowed scattering around in other directions.
[00042] According to an embodiment of the present invention, the at least one sealing member 206 includes an outer diameter OD of the outer diametrical surface 206d including a diameter of approximately 40mm, an inner diameter ID of the inner diametrical surface 206c including a diameter of approximately 22.8mm, and a thickness T of approximately 6mm.
[00043] According to another embodiment of the present invention, the at least one sealing member 206 includes a ratio between an outer diametrical surface 206d of said at least one sealing member 206 and said inner diametrical surface 206c of said at least one sealing member 206 varying in the range of approximately 1.15~2.4.
[00044] According to another embodiment of the present invention, the at least one sealing member is configured to accommodate an O-ring 208.
[00045] Although the subject matter has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein.
,CLAIMS:We claim:
1. An engine assembly (100) for a step-through scooter type motorcycle, said engine assembly (100) comprising:
a crankcase assembly (102);
a crankshaft assembly (201) housed within said crankcase assembly (102); and
a bearing assembly (202) including a LH bearing assembly (202a) and a RH bearing assembly (202b), said RH bearing assembly (202b) is disposed on one side of said crankshaft assembly (201) and the LH bearing assembly (202a) is disposed on another side of said crankshaft assembly (201), said bearing assembly (202) rotatably supports said crankshaft assembly (201),
wherein,
said crankshaft assembly (201) includes one or more accommodating portions (201ba, 201bb) including a first accommodating portion (201ba) and a second accommodating portion (201bb) to accommodate at least one moveable drive (204) and a bearing assembly (202) respectively and wherein, said crankshaft assembly (201) includes a well-defined space (201bc) disposed between said first accommodating portion (201ba) and said second accommodating portion (201bb) and wherein said well-defined space (201bc) is configured to accommodate at least a portion of an inner diametrical surface (206c) of at least one sealing member (206).
2. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1, wherein said well-defined space (201bc) is capable of accommodating a sprocket member (205), said sprocket member (205) is disposed between said at least one sealing member (206) and said bearing assembly (202).
3. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1, wherein said at least one sealing member (206) includes an axial ridge (206a) configured to abut against an outer diametrical surface of said crankshaft assembly (201), a plurality of deflecting portions (206b) disposed angularly in one direction only to enable streamlining of oil particles in said one direction.
4. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1, wherein said at least one sealing member (206) is configured to accommodate an elastic member (208).
5. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1, wherein said first accommodating portion (201ba) includes a first diameter (?1) of approximately 17mm, a second accommodating portion (201bb) includes a second diameter (?2) of approximately 23mm, and said well-defined space (201bc) includes a third diameter (?3) of approximately 22.8mm.
6. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1, wherein said at least one sealing member (206) includes an outer diameter (OD) of said outer diametrical surface (206d) including a diameter of approximately 40mm, an inner diameter (ID) of said inner diametrical surface (206c) including a diameter of approximately 22.8mm, and a thickness (T) of approximately 6mm.
7. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1, wherein said crankshaft assembly (201) includes an angular portion (R1) to accommodate a movable drive- plate (204a) capable of supporting said at least one movable drive (204), said angular portion (R1) includes a radius approximately in the range of 0.5-1.0 mm.
8. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1 or claim 2, wherein said at least one sealing member (206) is at a proximity to said movable drive (204) and said sprocket member (205) is at a proximity to said LH bearing assembly (202a).
9. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1 or claim 2, wherein said sprocket member (205) includes a shoulder portion (205a) extending annularly at one periphery (205o), said shoulder portion (205a) is capable of abutting against at least a portion of said LH bearing assembly (202a) and a plurality of toothed members (205b) extending radially outwardly from an another periphery (205p) of said sprocket member (205), said plurality of toothed members (205b) are capable of driving a cam chain (209).
10. The engine assembly (100) for a step-through scooter type motorcycle as claimed in claim 1 or claim 6, wherein said at least one sealing member (206) includes a ratio between said outer diameter (OD) of said outer diametrical surface (206d) and inner diameter (ID) of said inner diametrical surface (206c) varying in the range of approximately 1.0~2.5.