DESC:FIELD OF INVENTION
[0001] The present subject matter described herein generally relates to an internal combustion engine, and particularly but not exclusively relates to a starting system for an internal combustion engine of a saddle-type vehicle.
BACKGROUND OF INVENTION
[0002] An internal combustion engine, hereinafter ‘engine’, typically includes either a first type of starting system comprising a constant meshing type gear system including a starter motor with a pinion gear, an idler gear, a driven gear, and a one-way clutch attached to a rotor of a magneto assembly; or a second type of starting system comprising a starter motor with an integrated one way clutch which includes a pair of reduction gears & a driven gear typically attached to the rotor of the magneto assembly. While the first type of starting system is typically silent during engine starting, the second type of starting system is noisy during starting operation.
[0003] Operation of the starting system typically involves transmitting rotational force of the starter motor to a crankshaft of the engine through the one-way clutch, thereby starting the internal combustion engine. Particularly, rotational motion is transmitted from the starter motor to the idler gear and from the idler gear to the driven gear, which in turn is held in contact with the one-way clutch. Presence of the one-way clutch ensures that the crankshaft rotates in a single direction only.
[0004] In a known art, especially in a scooter type vehicle, the one-way clutch is coupled to a magneto assembly. However, coupling the one-way clutch to the magneto assembly entails the magneto assembly to be enclosed within the engine so that the one-way clutch coupled thereto is sufficiently lubricated with engine oil. In other words, coupling the one-way clutch to the magneto assembly demands a wet type magneto assembly which involves higher costs. Moreover, the engine of the scooter-type vehicle being typically enclosed by covers and not being directly exposed to on coming air stream while running, requires additional cooling which is typically achieved by providing a cooling fan. However, presence of a wet type magneto assembly does not permit a cooling fan to be attached thereto, requiring the cooling fan to be disposed elsewhere. Therefore, there is a need to overcome above mentioned problems.
[0005] Further, in the second type of starting system where the driven gear fitted on the rotor of the magneto assembly comes into contact with the idler gear by the forward motion during engine starting, an unpleasant noise is often generated. Also, typically a larger driven gear has to be provided for mounting on the rotor, thereby entailing higher costs.
[0006] In another known art, especially for a single speed constant ratio hybrid vehicle provided with engine & traction motor which are capable of driving the vehicle independently, the engine is provided with an automatic centrifugal clutch. However, in such vehicles using an automatic centrifugal clutch, it is unfeasible to mount the starting system over a clutch drum due to free rotation of the clutch drum over the crankshaft during idling. Therefore, an alternative location needs to be provided for mounting the starting system.
[0007] An integrated starter generator is typically provided to solve the problems associated with the above mentioned known arts. However, providing an integrated starter generator proves to be a costly affair. There is therefore a need to provide an optimum location for arrangement of the starting system while ensuring that the arrangement is compact, and that it does not generate noise during engine starting, while ensuring that cost of manufacturing is low. Moreover, it is also desirable to ensure sufficient lubrication around the one-way clutch.
[0008] It is therefore desired to address the problems encountered in the prior arts as discussed above.

BRIEF DESCRIPTION OF DRAWINGS
[0009] The detailed description of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.
[00010] Figure 1 illustrates a side view of a saddle-type vehicle in accordance with an embodiment of the present invention.
[00011] Figure 2 illustrates a side view of an internal combustion engine coupled to a transmission assembly of said saddle-type vehicle in accordance with an embodiment of the present invention.
[00012] Figure 3 illustrates a cross sectional view of the transmission assembly including a starting system in accordance with an embodiment of the present invention.
[00013] Figure 4 illustrates a detailed cross sectional view of the starting system in accordance with an embodiment of the present invention.
[00014] Figure 5 illustrates an exploded view depicting the starting system in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
[00015] The present invention has been devised in view of the above stated problems.
[00016] It is an object of the present invention to provide an internal combustion coupled to a transmission assembly, said transmission assembly comprising a starting system with a one-way clutch, the mounting of said starting system ensuring silent engine operation during starting.
[00017] It is another object of the present invention to provide a starting system including a one-way clutch, a mounting location of which ensures sufficient lubrication around parts of the starting system including the one-way clutch.
[00018] It is yet another object of the present invention to provide a starting system, the manner and location of mounting of which ensures durability of said starting system.
[00019] It is one more object of the present invention to provide a starting system which permits greater load to be transmitted to the crankshaft without causing damage to the crankshaft.
[00020] It is still another object of the present invention to provide a starting system which is compact and does not entail higher costs.
[00021] Accordingly, the subject matter described herein relates to an internal combustion engine, hereinafter ‘engine’ for a saddle type vehicle such as a scooter-type vehicle and a hybrid scooter-type vehicle, said engine being coupled to a transmission assembly disposed within a crankcase and adapted to transmit output of said engine to a rear wheel of the saddle-type vehicle. Particularly, the subject matter described relates to a starting system forming part of the transmission assembly. The starting system as per the present invention includes a starter motor, an idler gear, a driven gear, and a one-way clutch. Power/torque from the starter motor is transmitted to the driven gear through the idler gear, and from the driven gear to a crankshaft of the internal combustion engine through the one-way clutch. Particularly, as per an aspect of the present invention, the torque from the one-way clutch is transmitted to the crankshaft through a flange member in direct contact with the crankshaft.
[00022] As per an aspect of the present invention, the crankshaft is provided with a taper surface, which allows positive clamping of the flange member with the crankshaft, said flange member in turn being provided with a corresponding taper surface. Particularly, said taper surface enables axial clamping of the flange member with the crankshaft. However, torque transfer to the crankshaft from said flange member is achieved through a key member which is used to secure said flange member to the crankshaft. In the present embodiment, the one way clutch is not in direct contact with the crankshaft and is connected to the crankshaft through the flange member. As per one aspect of the present invention, the one-way clutch is detachably attached to the flange member. Clamping of the flange member with the crankshaft ensures better torque transfer without causing damage to the crankshaft. Thus, in the present embodiment, load transfer to the crankshaft is achieved through surface contact of the flange member with the crankshaft.
[00023] As per another aspect of the present invention, the starting system including the one-way clutch is arranged on a clutch side of the crankshaft and away from a magneto assembly arranged on a magneto side of the crankshaft. Providing the starting system on the clutch side of the crankshaft ensures that there is availability of sufficient lubricant around parts of the starting system including the one-way clutch, unlike in the case where the one-way clutch is assembled on a rotor of the magneto assembly, while ensuring that there is no splashing of the lubricant towards the outside due to presence of a cooling fan on the magneto side of the crankshaft. Thus, arrangement of the starting system on the clutch side of the crankshaft also allows a cooling fan to be conveniently arranged on the magneto side of the crankshaft.
[00024] Summary provided above explains the basic features of the invention and does not limit the scope of the invention. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to the accompanying drawings.
[00025] Exemplary embodiments detailing features of the starting system, in accordance with the present invention will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present invention will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. Further, it is to be noted that terms “upper”, “lower”, “right”, “left”, “front”, “forward”, “rearward”, “downward”, “upward”, “top”, “bottom” and like terms are used herein based on the illustrated state or in a standing state of the saddle-type vehicle with a driver sitting thereon unless otherwise elaborated. Furthermore, a longitudinal axis refers to a front to rear axis relative to said vehicle, defining a vehicle longitudinal direction; while a lateral axis refers to a side to side, or left to right axis relative to said vehicle, defining a vehicle lateral direction. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. Further, although the present invention has been exemplified for a hybrid scooter-type vehicle, the present invention is also applicable for conventional scooter-type vehicles powered by a CVT engine.
[00026] Arrows provided in the top right corner of each figure depicts direction with respect to the motorcycle, wherein an arrow F denotes front direction, an arrow R indicates rear direction, an arrow Up denotes upward direction, an arrow Dw denoted downward direction, an arrow Rh denotes right side, an arrow Lh denoted left side, as and where applicable.
[00027] With reference to FIG. 1, a description is made of a saddle-type vehicle (10) such as a hybrid scooter-type vehicle. As shown in FIG.1, said vehicle (10) includes a body frame (11), for example an underbone body frame. Said body frame (11) which forms a skeleton of said vehicle (10), is covered by different body covers. A front cover (1) is provided to cover a forward facing side of the body frame (11) and is disposed above a front fender (2). A headlamp cover (3) is disposed above the front cover (1) to encompass a headlamp (9) and a handle bar (5) at least partially.
[00028] Further, a leg shield (6) is disposed on a rear side of the front cover (1), which serves to protect a rider’s legs from running wind. From a lower portion of the leg shield (6), a floorboard (7) extends in a vehicle longitudinal direction towards a central cover member (4) of said vehicle (10). A side cover (8) each extending rearwardly towards a rear end of said vehicle (10) is disposed on either sides of a seat (12) and serves to cover internal parts of said vehicle and prevent foreign particles from internal entering parts of said vehicle. Further, said side cover (8) disposed on either sides of the seat (12) serves to enhance the overall aesthetics of said vehicle (10).
[00029] Suspension systems are provided for comfortable steering of said vehicle (10) on the road. A front fork assembly (23), which forms the front suspension system, serves as rigidity component just like the body frame (11). The front fork assembly (23) clamped to a head pipe (not shown) is capable of being moved to the left and right. Further, a rear suspension system (24), which is a hydraulic damped arrangement, is connected to the body frame (11) at a rear portion thereof. Particularly, at the rear portion of the body frame (11), a rear wheel (20) is suspended by the rear suspension system (24).
[00030] In the present embodiment, said vehicle (10) is powered either by an internal combustion engine (15) or by a traction motor (not shown) independently or by both the engine (15) and the traction motor simultaneously. The traction motor is mounted on a hub of a rear wheel (20). A battery (not shown) is also provided to supply power to the traction motor. However, in another embodiment, said vehicle (10) may be powered only by the internal combustion engine (15). Further, power from said engine (15) and the traction motor is transmitted by a transmission assembly (25) (shown in FIG.2) to the rear wheel (20). The transmission assembly (25) may include a fixed gear chain drive.
[00031] In another embodiment, say said vehicle (10) is a normal fuel powered vehicle like a saddle-type scooter or a saddle-type motorcycle, in such a case said vehicle (10) may be powered by the internal combustion engine (15) alone, and power from the internal combustion engine (15) to the rear wheel (20) may be transmitted by the transmission assembly (25) including a CVT or a gear transmission respectively.
[00032] For example, as may be seen in FIG.2, the internal combustion engine (15) is connected to the transmission assembly (25), said transmission assembly (25) being housed within a crankcase (25a). The crankcase (25a) also supports a crankshaft (16) of the engine (15). The transmission assembly (25) as per the present embodiment and as may be seen in FIG.2 includes a primary drive system comprising suitable power transmission elements such as an input gear (17) for transferring power from a crankshaft (16) of the internal combustion engine (15) to an input shaft (not shown) of the transmission assembly (25). Further, an output shaft (not shown) disposed parallel to the input shaft, and on which is journaled an output gear, transmits power to a shaft of the rear wheel, for driving the rear wheel.
[00033] Further, the transmission assembly (25) as per the present embodiment and as may be seen in FIG.3 may be divided into four chambers formed along a length of the crankshaft (16), namely a dry chamber (DC) for housing a magneto assembly (26), a crank chamber (CC) for housing at least a portion of the crankshaft (16), an oil pump chamber (OC) for accommodating an oil pump, and a clutch operating chamber (LC) for accommodating a clutch assembly (CA). In the present embodiment, the clutch assembly (CA) comprises an automatic centrifugal clutch.
[00034] As per an aspect of the present invention, the transmission assembly (25) also includes a starting system (30) for starting the engine (15). Particularly, the starting system (30) as may be seen is disposed within the clutch operating chamber (LC) and besides the oil pump chamber (OC) on a clutch side of the crankshaft (16) and disposed away from magneto assembly (26) housed in the dry chamber (DC). Disposing the starting system (30) away from the magneto assembly (26) and the provision of the dry chamber (DC) for accommodating the magneto assembly (26), allows a cooling fan (27) to be mounted/ disposed near the magneto assembly (26). Since, the dry chamber (DC) is provided for the magneto assembly (26), it is ensured that no splashing of lubricant occurs to the outside during the operation of the cooling fan (27). Moreover, disposing the starting system (30) including a one-way clutch (34) (shown in FIG.4) besides the oil pump chamber (OC) inside the crankcase ensures that sufficient lubrication is available for the lubrication of the starting system (30). For example, the starting system (30) including the one-way clutch (34) is lubricated by splash lubrication. Availability of sufficient lubrication around the starting system (30) ensures durability and optimal functioning of the starting system (30).
[00035] With reference to FIG.4 and FIG.5, a detailed explanation is made of the starting system (30). FIG.4 and FIG.5 depict parts of the starting system (30) and an arrangement thereof in accordance with an embodiment of the present invention. As may be seen in FIG.5, the starting system (30) as per the present embodiment includes a starter motor (31), an idler gear (32) operatively connected to said starter motor (31), a driven gear (33) meshing with the idler gear (32), the one-way clutch (34) operatively connected to said driven gear (33), and a flange member (35) detachably attached to the one-way clutch (34) and in direct contact with the crankshaft (16) of the engine (15). Thus, parts of the starting system (30) are disposed over at least a portion of length of the crankshaft (16). Moreover, detachably attaching the one-way clutch (34) with the flange member (35) rather than with the starter motor aids in ensuring that compactness of the starting system is achieved.
[00036] As per an aspect of the present invention and as may be seen in FIG.4, the crankshaft (16) is provided with a taper surface (16a). The starting system (30) is disposed over the crankshaft (16), with the flange member (35) being held over the taper surface (16a) of the crankshaft (16). Particularly, while the driven gear (33) is held in contact with the crankshaft (16) through a needle bearing (36), the flange member (35) is held in direct contact with the taper surface (16a) of the crankshaft (16) through a corresponding taper surface (35a) provided therein. In the present embodiment, the flange member (35) is secured to the crankshaft (16) by a key member (37), said key member (37) being held in a cavity (16b) provided in the taper surface (16a) of the crankshaft (16). While the corresponding taper surface (35a) of the flange member (35) aids in axial clamping of the flange member (35) with the crankshaft (16), the key member (37) aids in torsional clamping of the flange member (35) with the crankshaft (16). Providing the taper surface (16a) for the crankshaft (16) ensures that torque transfer to the crankshaft (16) is through the key member (37) in contact with the taper surface (16a) rather than splines conventionally provided on the crankshaft (16). Provision of the taper surface (16a) ensures better torque transfer to the crankshaft (16) without causing breakage of the crankshaft (16), which is specifically useful for application in hybrid vehicles. In other words, load transfer through surface contact with the crankshaft (16) ensures higher load carrying capacity of the crankshaft (16). Moreover, manufacture of a crankshaft having a taper surface rather than a splined surface is easier and is not prone to manufacturing defects arising due to manufacturing variations.
[00037] The operation of the starting system (30) in accordance with the present invention is now elaborated with reference to FIG.4 and FIG.5. When the starter motor (31) is actuated, driving force or rotational force of the starter motor (31) is transmitted to the idler gear (32), and from the idler gear (32) to the driven gear (33). The driven gear (33) in turn rotates the one-way clutch (34) which is disposed on a hub (33a) thereof. The one-way clutch (34) being attached to the flange member (35) rotates the flange member (35), which in turn rotates the crankshaft (16). Presence of plurality of rollers (34a) in the one-way clutch (34) ensures that the one-way clutch rotates in a single direction only. Moreover, since the one-way clutch (34) is attached to the flange member (35), the flange member (34) is also made to rotate in a single direction only. Particularly, as may be seen in FIG.5, the one-way clutch (34) is detachably attached to the flange member (35) by means of fasteners (38) and disposed over the hub (33a) of the driven gear (33). Thus, torque transfer to the crankshaft (16) occurs through the flange member (35) which in turn ensures that the crankshaft (16) rotates in a single direction only. In the present embodiment, the key member (37) serves to transfer torque to the crankshaft (16) and also serves to align the flange member (35) with the crankshaft (16).
[00038] Once the crankshaft (16) starts rotating, and the power to the starter motor (31) is cut off, the driven gear (33) becomes stationary. At the same time, radius of the plurality of rollers (34a) of the one–way clutch (34) increases from a crankshaft axis (C), thereby resulting in loss of contact between the one-way clutch (34) and the driven gear (33), and the one-way clutch (34) starts rotating on the hub (33a) freely.
[00039] Thus, as is apparent from the above teaching, since sufficient lubrication of the starting system is ensured by disposing the starting system besides the oil pump chamber and within the clutch operating chamber and since there is constant meshing between the idler gear and the driven gear, silent operation is ensured during starting of the engine. Moreover, since the elements of the starting system including one-way clutch are not integrated with the starter motor, compactness of the starting system is also achieved. Also, since the splined surface in the crankshaft is eliminated, variations in the elements constituting starting system can be avoided, thereby preventing frequent replacement of parts and associated costs. Moreover, elimination of the splined surface also aids in noise reduction in the starting system. Further, presence of the taper surface also ensures that the load carrying capacity of the crankshaft is improved.
[00040] 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 as defined in the appended claims: ,CLAIMS:We Claim:
1. An internal combustion engine (15) for a saddle type vehicle (10), said internal combustion engine (15) being coupled to a transmission assembly (25) disposed within a crankcase (25a), and comprising a crankshaft (16) supported by said crankcase (25a);
wherein the transmission assembly (25) includes a dry chamber (DC), a crank chamber (CC), an oil pump chamber (OC) and a clutch operating chamber (LC) disposed along a length of the crankshaft (16), and wherein the transmission assembly (25) includes a starting system (16) comprising a driven gear (33), and a one-way clutch (34) for starting the internal combustion engine (15);
characterized in that, the starting system (34) is disposed over the crankshaft (16) besides said oil pump chamber (OC) and within the clutch operating chamber (LC).
2. The internal combustion engine (15) as claimed in claim 1, wherein the crankshaft (16) is formed with a taper surface (16a), said taper surface (16a) being in direct contact with at least a portion of the starting system (30).
3. The internal combustion engine (15) as claimed in claim 1 or claim 2, wherein the starting system (30) includes a flange member (35) held in direct contact with said taper surface (16a) of the crankshaft (16).
4. The internal combustion engine (15) as claimed in claim 3, wherein said flange member (35) includes a corresponding taper surface (35a) for direct contact with said taper surface (16a) of the crankshaft (16).
5. The internal combustion engine (15) as claimed in claim 3, wherein said flange member (35) is secured to said taper surface (16a) of the crankshaft (16) by a key member (37).
6. The internal combustion engine (15) as claimed in claim 5, wherein said taper surface (16a) includes a cavity (16b) for receiving said key member (37).
7. The internal combustion engine (15) as claimed in claim 4, wherein said corresponding taper surface (35a) enables axial clamping of said flange member (35) with the crankshaft (16).
8. The internal combustion engine (15) as claimed in claim 5, wherein said key member (37) enables torsional clamping of said flange member (35) to the crankshaft (16).
9. The internal combustion engine (15) as claimed in claim 3, wherein said flange member (35) is detachably attached to the one-way clutch (34).
10. A saddle-type vehicle (10) comprising the internal combustion engine (15) as claimed in claims 1-9.