DESC:TECHNICAL FIELD
[0001] The present subject matter relates generally to an internal combustion engine for a two wheeled vehicle. More particularly, the present subject matter relates to an electric start system to crank the internal combustion engine of the two wheeled vehicle.
BACKGROUND
[0002] An internal combustion (IC) engine converts thermal energy obtained from burning of a fuel with an oxidizer (air) into mechanical energy, which can be employed to provide motive force for movement of an automobile. The main parts of the internal combustion (IC) engine include a cylinder head, a reciprocating piston on a cylinder block and a connecting rod which connects the piston to a crankshaft which rotates due to the corresponding reciprocating motion of the piston due to slider crank mechanism. During starting of the internal combustion (IC) engine, the crankshaft needs to be cranked in order to bring the internal combustion (IC) engine into operating mode. There are various methods by which cranking of the internal combustion (IC) engine can be achieved. One of the common methods of the cranking is to use an electric motor to provide the necessary cranking revolutions to the crankshaft required to bring the internal combustion (IC) engine to operating mode. Another method fast emerging is to use an integrated starter generator (ISG) system to provide cranking revolutions to the crankshaft. The ISG functions both as a generator to generate power and charge a battery and start the internal combustion (IC) engine based on different operating conditions. The internal combustion (IC) engine comprising the ISG systems can also perform multiple functions such as starting, charging the battery, internal combustion (IC) engine stop and start to conserve fuel, and provides regenerative braking. In order to implement the electric start system or the ISG system, each requires different parameters of internal combustion (IC) engine design. In case of electric motor, the position and location of the electric motor and taking into account the necessary gearing mechanism required to realise the operation of cranking is a very important parameter in the design of the Internal combustion (IC) engine. This design requirement is especially important for the internal combustion (IC) engines of two wheeled vehicles, as they are smaller in dimensions, compact in nature and constrained in their packaging in internal combustion (IC) engine layout when accommodating various components. Due to technology advancement, ease of assembly and requirement to meet various customer needs, it is necessary to develop an internal combustion (IC) engine capable of accommodating many alternate solutions such as implementing an ISG system to crank the internal combustion (IC) engine with minimal changes in internal combustion (IC) engine layout. Keeping in light of the following aspects, it is a desirable to provide a starting system and a corresponding crankcase for the Internal combustion (IC) engine which is easy to assemble or dis-assemble giving flexibility of having same Internal combustion (IC) engine with both ISG system variant and electric start system/magneto assembly variant. But, such design systems often involves critical design changes which is crucial while manufacturing the internal combustion (IC) engine. Hence, with an aim to achieve interoperability it is desirable to provide an internal combustion (IC) engine which can accommodate both electric start system and ISG system without any major change in design and manufacturing set-up of the internal combustion (IC) engine.

BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0004] Fig. 1. illustrates a side view of a two wheeled vehicle employing an embodiment of the present subject matter.
[0005] Fig. 2. illustrates a perspective view of an Internal combustion (IC) engine with a detachable electric start system according to the embodiment of the present subject matter.
[0006] Fig. 3. illustrates a perspective view of the Internal combustion (IC) engine with a first cover and detachable electric start system disassembled according to the embodiment of the present subject matter.
[0007] Fig. 4. illustrates an enlarged cut sectional view (X-X) illustrating the detachable electric start system and the RH crankshaft according to the embodiment of the present subject matter.
[0008] Fig. 5. illustrates a perspective view of the detachable electric start system according to the embodiment of the present subject matter.
[0009] Fig. 6. illustrates an exploded view of the detachable electric start system according to the embodiment of the present invention.
[00010] Fig. 7. illustrates a perspective view of the Internal combustion (IC) engine with the first cover and a cap covering the opening according to the embodiment of the present subject matter.
[00011] Fig. 8. illustrates a perspective view of the Internal combustion (IC) engine with the first cover with the cap and a spacer disposed on the crankshaft replacing a ring gear and a one way clutch according to the embodiment of the present subject matter.
[00012] Fig. 9. illustrates a perspective view of the assembly of the spacer disposed on the crankshaft according to the embodiment of the present subject matter.

DETAILED DESCRIPTION
[00013] Various features and embodiments of the present subject matter here will be discernible from the following further description thereof, set out hereunder. According to an embodiment, an internal combustion engine (IC) described here operates in four cycles. Such an Internal combustion (IC) engine is installed in a step through type two wheeled vehicle. It is contemplated that the concepts of the present invention may be applied to other types of vehicles such as straddle type vehicle having vertical oriented cylinder axis 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 Internal combustion (IC) engine and looking forward. Furthermore, a longitudinal axis unless otherwise mentioned, refers to a front to rear axis relative to the engine, while a lateral axis unless otherwise mentioned, refers generally to a side to side, or left to right axis relative to the engine. 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.
[00014] Typically, an Internal combustion (IC) engine comprises a cylinder block having a cylinder bore, a piston reciprocating in the cylinder bore, a cylinder head located above the cylinder block and a combustion chamber interposed between the cylinder head and cylinder block. Air fuel mixture is ignited in the combustion chamber which expands imparting motion to the piston which reciprocates and is converted to rotary motion of a crankshaft through a connecting rod. Further, the motion from the crankshaft is transmitted to wheels of a two wheeled vehicle through a transmission system. Generally, the internal combustion (IC) engine comprises of a magneto assembly disposed at one end of the crankshaft. However recent advances in technology have given rise to integrated starter generator (ISG) which can function as a magneto assembly generating power and charging the battery during operation of Internal combustion (IC) engine, and function as an electric motor capable of providing initial revolutions to the crankshaft to start the Internal combustion (IC) engine. Additionally, the ISG system is used for performing multiple functions such as starting, charging the battery, Internal combustion (IC) engine stop and start to conserve fuel, and provides regenerative braking. ISG systems have advantages such as, they can eliminate the use of separate electric start system as only a passive component during engine operation, can charge the battery, helps in reducing fuel consumption, quick response, reduction in emissions, have extremely compact dimensions, eliminate the slip rings and the brushes in starter motor and hence eliminate noise. The engine can be designed suitably to eliminate separate electric start components and allied internal combustion (IC) engine components which are present in the internal combustion (IC) engine on introduction of ISG system.
[00015] However, ISG system is expensive and the cost of two wheeled vehicle can increase to substantial amount. This is because, we need to substantially increase the size and capacity of the battery as ISG requires high starting torque, operating at wide magnetic field and requires extremely intricate design changes which involve use of additional copper wiring and larger metal cores which cumulatively increase weight, operation of ISG requires expensive electronic circuitry and specialized power systems which add to cost, and in addition ISG requires frequent serviceability and many times frequent replacement. Also, modern ISG comes with additional features such as engine start –stop during the internal combustion (IC) engine idling conditions, and all of these factors cumulatively add to increased cost of the two wheeled vehicle. The percentage cost increase in implementing the ISG system as compared to normal electric start system is around 10% increase in cost, and in addition cost of frequent servicing make it an expensive addition to the two wheeled vehicle. It is undesirable to transfer the burden of increased cost to the customer. In that scenario, electric motor start systems have an edge over greater technologically advanced ISG systems as they are cost effective and affordable. Hence, it is desirable to design the internal combustion (IC) engine and the electric start system to achieve interoperability and flexibility during manufacturing of the internal combustion (IC) engine, such that the internal combustion (IC) engine can be inter-operably assembled to have the electric start system variant and ISG system variant. Hence, it is a primary objective of the present invention to provide the Internal combustion (IC) engine design wherein there are two variants of the two wheeled vehicle available which offer the customer a choice to choose between a more expensive ISG variant and a less expensive electric start variant.
[00016] To achieve the above objective, it is necessary to design the Internal combustion (IC) engine having the electric start system such that, it at the time of manufacturing and assembly one can easily and interchangeably assemble the ISG system or the electric start system. But, adopting such flexibility involves considerable design challenges. A mounting location should be provided on the internal combustion (IC) engine crankcase for the electric start system. But, in case the Internal combustion (IC) engine assembled with the ISG, additional components such as intermediate gear, ring gear and one-way clutch need not to be provided on the crankshaft which occupies weight and incurres unnecessary wastage of material which adds to manufacturing cost. Also, design of the internal combustion (IC) engine is such that involves exposure of crankcase components if the electric start system is removed in normal internal combustion (IC) engines having electric start. Further, additional machining operations are required to accommodate electric start. Hence, it is not practically feasible and financially not viable to offer two variants based on existing design.
[00017] To achieve the aim of designing an Internal combustion (IC) engine and providing the electric start system which can also implement an ISG, it is proposed a detachable type electric start system wherein, the electric motor can be easily attached and detached to the Internal combustion (IC) engine, such that interoperability between implementing electric start system and ISG system is obtained. The solution proposed is simple in construction, reliable and effective in operation. Further, the crankcase of the internal combustion (IC) engine is suitably designed to provide provision for attaching the electric start system and mounting slots are provided to enable ease of attachment and detachment.
[00018] With the above design changes, the following advantages can be obtained such as simple in construction, reliable and effective in operation, ease of interoperability, avoiding use of additional elements such as additional brackets, and easy to remove and mount giving rise to improved serviceability.
[00019] According to the present subject matter to attain the above mentioned objectives, a first characteristic of the present invention is the Internal combustion (IC) engine comprising: a crankcase, said crankcase enclosing a crankshaft; a detachable electric start system configured to transmit drive to the crankshaft during starting of the Internal combustion (IC) engine; wherein, said detachable electric start system configured to be detachably attached to the crankcase assembly; said crankcase assembly comprising plurality of mounting slots to receive said electric start system; said crankcase comprising an opening to receive the electric start system to transmit drive to the crankshaft; and said electric start system comprising: an electric motor; an intermediate gear operably connected to the electric motor and operably meshed with the crankshaft through the opening; a right-hand crankcase cover configured to enclose the electric motor, and at least part of the intermediate gear.
[00020] In addition to the configuration of the first characteristic, the second characteristic of the present subject matter is the Internal combustion (IC) engine, wherein the crankcase assembly extends rightward and leftward in the Internal combustion (IC) engine width direction, said crankcase assembly comprising a top surface, and a bottom surface, and a plurality of side surfaces of the crankcase, wherein the side surfaces are substantially vertical and configured to extend between the top surface and the bottom surface, and said opening is disposed on the top surface in the rightward part of the crankcase assembly.
[00021] The Internal combustion (IC) engine as described above can now be implemented to be used in two variants namely in electric start mode wherein, the detachable electric start system in detachably attached to the crankcase assembly. Further, if it is desired to be used in ISG mode, then the detachable electric start system can be detached (or need not be assembled during manufacturing as the case maybe) and the opening on the crankcase assembly is covered with a cap, said cap matching the exact contours of the opening, and said cap mounted on plurality of mounting slots on the crankcase assembly. Furthermore during usage in ISG mode, the ring gear and the one way clutch can be removed and replaced with a spacer having width equal to that of the ring gear and the one way clutch.

[00022] The present subject matter along with all the accompanying embodiments and their other advantages would be described in greater detail in conjunction with the figures in the following paragraphs.
[00023] The present subject matter envisages an Internal combustion (IC) engine comprising the detachable electric start system which can be detachably attached and hence provide ease of assembly and one common single design to implement both electric start system and ISG system in a single Internal combustion (IC) engine. Further, the design enables any person to replace the electric start system with the ISG system whenever one desires. Furthermore, if it is decided at the time of manufacturing and assembly to implement ISG system, then it is possible to implement in the same internal combustion (IC) engine and also save on manufacturing cost. Fig. 1 to Fig. 6 illustrates the Internal combustion (IC) engine having detachable electric system, Fig. 7 describes the detachment of the detachable electric start system and covering the opening with a cap to cover the opening to prevent its exposure and entry of contaminants and also prevent leakage of lubricating oil, Fig. 8 & Fig. 9 illustrates the same Internal combustion (IC) engine but manufactured by assembling the ISG system within it.
[00024] Fig. 1 illustrates a two wheeled vehicle, having an Internal combustion (IC) engine (101) having an automated manual transmission (AMT) system according to one embodiment of the present subject matter. It is to be noted that, the present embodiment is by no means a limitation and the invention can be implemented in any Internal combustion (IC) engine (101) other than the AMT engine which substantially has a similar engine layout, without deviating from the scope of the present invention and will be apparent to a person skilled in the art. The two wheeled vehicle is a step through vehicle with the internal combustion (IC) engine (101) swingably connected below a frame assembly. The frame assembly comprises of a head tube (102), a down tube (107), a step-through through structure (117), a pair of side frame tubes (109) (only one shown), and a swing arm assembly. The head tube (102) supports a steering shaft (not shown) with two brackets – upper bracket (not shown) and lower bracket (not shown) at each end. Two telescopic front suspension (121) (only one shown) is attached to the lower bracket (not shown) on which is supported the front wheel (119). The upper portion of the front wheel (119) is covered by a front fender (103) mounted to the lower portion of the steering shaft. A handlebar assembly (124) is fixed to steering shaft on the upper portion of the upper bracket (not shown) and can rotate to both sides. The handlebar assembly (124) comprises of a visor assembly (not shown) which encloses the handlebar (106), mirror assembly (105), instrument cluster (not shown) and a headlight (104). The down tube (107) extends downwardly from an upper portion of the head pipe (102) and joins the step-through structure (117). The pair of side frame tubes (109) (only one shown) extends upwardly and rearwardly forming a substantially horizontal direction from the step-through structure (117) as seen from the side view of the two wheeled vehicle. A plurality of cross brackets (not shown) is secured in between the pair of side-tubes (109) to support vehicular attachments including a utility box (not shown), a seat (108), a pillion hand-rest (118) and a fuel tank assembly (not shown).
[00025] A left and right rear swing arm bracket (not shown) is pivoted on the frame assembly at the rear of the step-through structure (117), and supports a swing arm assembly. The swing arm assembly comprises of the left and right swing arms (115) (only one shown) pivoted to the left and right rear swing arm brackets (not shown), and is capable of swinging vertically about the pivot and supported through two rear wheel suspensions (111) arranged of the rear of the swing arm assembly. The Internal combustion (IC) engine (101) is swingably supported on the swing arm assembly. The rear wheel (113) is connected to rear end of the swing arm assembly and configured to rotate by the driving force of the Internal combustion (IC) engine (101) transmitted through a chain drive (not shown) from the Internal combustion (IC) engine (101). A rear fender (110) is covering at least a portion of the rear wheel (113) and it is positioned below the fuel tank (not shown). The Internal combustion (IC) engine (101) also comprises a kick-starter system which when actuated by the kick-lever helps in cranking the Internal combustion (IC) engine during start. The automated manual transmission (AMT) Internal combustion (IC) engines usually have a stepped transmission system such as that of constant mesh gear transmission system having plurality gear shifts which automatically change speed ratios based on power and torque requirements. The two wheeled vehicle also comprises of plurality of electrical and electronic components including a headlight (104), a taillight (112), and a transistor controlled ignition (TCI) unit (not shown).
[00026] Fig. 2 illustrates the enlarged isometric rearward view of the internal combustion (IC) engine (101). The Internal combustion (IC) engine (101) is made up of a cylinder head (201), a cylinder block (202), a cover oil filter (204), a cover clutch (205) and a crankcase assembly (203). The cylinder head (201) is covered by a cylinder head cover (201a). The crankcase assembly (203) is made up of left-hand crankcase (203a) (hereafter LH crankcase), right-hand crankcase (203b) (hereafter RH crankcase), and one or more crankcase covers (203c, 203d). The one or more crankcase covers (203c, 203d) include at least a first cover (203c) and a second cover (203d). For instance, in an embodiment, the first cover (203c) is interchangeably used as a right-hand crankcase cover (203c) (RH cover) and the second cover (203d) is interchangeably used as a left-hand crankcase cover (203d) (LH cover). In embodiment the internal combustion (IC) engine (101) used the automated manual transmission (AMT) system. The Internal combustion (IC) engine (101) having the automated manual transmission (AMT) system comprises of a clutch actuation system (207), a gear actuation system (206), a clutch sensor (207a), a magneto sensor pulsar coil (not shown), a gear sensor (not shown), a throttle sensor (not shown) located on the throttle body (not shown) and a vehicle speed measuring sensor (not shown). The clutch actuation system (207) is operably connected such that, when it is powered, it engages or disengages a clutch (not shown) with the aid of the clutch actuation motor based on inputs by the clutch sensor (207a). Additionally, there is a mechanically operated clutch lever (207b) which is provided for safety, which can be operated by the driver incase the clutch actuation system fails. The gear actuation system also comprises of a gear actuation motor (206), which is connected to a gear-shifting cam (not shown) and configured to execute gear shifts based on inputs from the gear sensor (not shown). Fig. 2a. also illustrates the detachable electric start system according to the embodiment of the present subject matter is shown, arranged to cover a part of the Internal combustion (IC) engine (101). In the present embodiment, it is disposed on the upper surface of the first cover (203c).
[00027] Fig. 3. illustrates an exploded view of the Internal combustion (IC) engine (101) with the removal of the first cover (203c) and the mounting of the detachable electric start system (301) according to the embodiment of the present subject matter. The detachable electric start system (301) in one embodiment is mounted on the first cover (203c) disposed substantially on the upper portion of the first cover (203c). The detachable electric start system (301) comprises an electric motor which is preferably mounted with the electric start system (301) main body facing the left direction in the vehicle width direction as seen from the vehicle rear to effectively utilize the space above the crankcase assembly (203) and additionally, due the presence of additional components required for the automated manual transmission (AMT) engine such as gear motor, the main body of the electric motor (301a) if facing right in the vehicle width direction could foul with some of the components. Hence, preferably it is oriented towards the left side. The first cover (203c) comprises various components to accommodate automatic manual transmission system components and when separated from the crankcase assembly (203) exposing the right hand side of the crankshaft (304).
[00028] The first cover (203c) in the Fig. 3 is removed to expose the internal components. The Internal combustion (IC) engine (101) comprises the crankshaft (304) through which a drive is obtained. The RH portion of the crankshaft (304) currently exposed, further comprises a ring gear (302) and a one-way clutch (303). The one-way clutch (303) comprises an outer portion and an inner portion, and the ring gear (302) is integrally attached to the outer portion and mounted on it. The inner portion of the one-way clutch (303) is integrally mounted on the crankshaft (304). When the vehicle is to be cranked, the detachable electric start system (301) provides rotary motion which is transmitted to the ring gear (302). The one-way clutch (303) permits rotary motion from the ring gear (302) to the crankshaft (304) through the outer portion and inner portion, but not from the crankshaft (304) back to the ring gear (302). Hence, when the detachable electric start system (301) transmits rotary motion to the ring gear (302), the one-way clutch (303) transmits the motion to the crankshaft (304) and consequently this rotary motion is used to crank the internal combustion (IC) engine (101). Once, the speed of the Internal combustion (IC) engine (101) picks up and the rotational speed of the internal combustion engine (101) exceeds the rotary speed of the detachable electric start system (301), the one-way clutch (303) prevents transmission of this rotary motion back to the detachable electric start system (301), and enables it to be disengaged.
[00029] The first cover (203c) comprises an opening (305), approximately having suitable dimensions such that, when first cover (203c) is assembled the geared teeth of the ring gear (302) is exposed and consequently accessible through this opening (305). The opening (305) permits access for any gear mechanism to partially enter the opening (305) and mesh with the ring gear (302) with an aim to aid in starting of the Internal combustion (IC) engine (101). In the present embodiment, the detachable electric start system (301) is mounted on the first cover (203c) such that an intermediate gear (501) of the detachable electric start system (301) meshes with the ring gear (302). Fig. 4 illustrates an enlarged cut sectional view of a section (X-X) of the internal combustion (IC) engine (101) which illustrates the meshing of the intermediate gear (501) of the detachable electric start system (301) with the ring gear (302). Preferably in an embodiment, the opening (305) is approximately in the rectangular in shape with presence of four corners. A plurality of mounting slots (345) having internal threading are drilled approximately on each of the four corners around the areas of cylinder bosses formed integrally on the first cover (203c). The detachable electric start system (301) is mounted on the first cover (203c) over the opening (305) using fasteners (308) connecting the detachable electric start system (301) to the plurality of mounting slots (345). An oil gasket (307) is disposed between the detachable electric start system (301) and the opening (305) during mounting to prevent the leak of lubricating oil which has a tendency to splash from the interior portions of the crankcase assembly (203).
[00030] As seen in Fig. 4, the one-way clutch (303) is mounted on the right hand portion of the crankshaft (304) and the ring gear (302) is mounted on the outer portion of the one-way clutch (303). An inner portion of the one-way clutch (303) extends axially towards the centre of the crankshaft (304). The inner portion is mounted integrally to the crankshaft (304) by a key joint by inserting keys. The first cover (203c) is assembled and the opening (305) located on the upper side of the outer surface of the first cover (203c) such that, the ring gear (302) has its teeth positioned just below the opening (305). The detachable electric start system (301) has the intermediate gear (501) projecting just outside a motor sheath (301b) such that, when placed over the opening (305) and assembled the intermediate gear (501) can perfectly mesh with the ring gear (302). Based on the measured tolerances of various components used for assembly, the degree of meshing can be adjusted by applying suitable torque to locking nuts (309) used to tighten the fasteners (308) during assembly. This arrangement ensures that, during starting of the Internal combustion (IC) engine (101), starting is made possible by the transfer of rotary motion from the detachable electric start system (301) to the ring gear (302) which rotates the Internal combustion (IC) engine (101). Once, the internal combustion (IC) engine (101) is started and in operation, the number of revolutions of the inner portion of the one-way clutch (303) is greater than the outer portion which disengages the ring gear (302) from rest of the crankshaft (304).
[00031] Fig. 5 and Fig. 6 illustrates the isometric view and the exploded view of the detachable electric start system (301) according to an embodiment of the present subject matter. The detachable electric start system (301) comprises, the electric motor (301a), an electric motor output drive (505) emerging from the electric motor (301a), the intermediate gear (501), an idler shaft (504), a bush (506), and the motor sheath (301b). The bush (506) is provided to control axial movement of the intermediate gear (501). The electric motor output drive (505) is meshed to the intermediate gear (501) which is freely supported on the idler shaft (504). The idler shaft (504) has its one end (504a) attached on the inner side of the motor sheath (301b) and the other end is tightened by a locking nut (310) and washer arrangement (311) such that the entire assembly is assembled to lie on an axis (Y-Y). The motor sheath (301b) is configured to house and support the above arrangement. Further, on another axis (Z-Z) located below axis (Y-Y) as viewed from the top towards the hollow direction of the motor sheath (301b), the electric motor (301a) is inserted on another opening (520) on the motor sheath (301b) to mount an electric motor (301a). The electric motor (301a) is inserted and mounted such that, the electric motor output drive (505) is enveloped by the motor sheath (301b) and is capable of meshing with the intermediate gear (501). The electric motor (301a) has an integral bracket (502) comprising threaded bores which are capable of mating with corresponding bosses present on the motor sheath (301b). In an embodiment, the intermediate gear (501) is an idler gear (501). The intermediate gear (501) comprises of two sets of gear portions (501a & 501b) having different set of teeth located adjacent to each other. The second gear portion (501b) is meshed with the electric motor output drive (505) while the first gear portion (501a) is meshed with the ring gear (302). The intermediate gear (501) comprising two gear portions serving two different functions. Firstly, the ring gear (302) and the electric motor output drive (505) have different sized gear teeth having different pitch, and hence it is impossible by design to provide a single gear portion to transmit the drive from the electric motor output drive (505) to the ring gear (302). Secondly, the difference is diameters of the first gear portion (501a) and the second gear portion (501b) aids in obtaining optimum revolutions desirable to provide starting revolutions and torque to the internal combustion (IC) engine (101) to start it. For instance, in an embodiment, during starting of the Internal combustion (IC) engine (101), starting is made possible by the transfer of rotary motion from the electric motor (301a) of the detachable electric start system (301) through the electric motor output drive (505) to the second gear portion (501b) of the intermediate gear (501) to the ring gear (302), which is meshed with the first gear portion (501a) of the intermediate gear (501). This enables rotation of the crankshaft (304) allowing the internal combustion engine (101) to start.
[00032] Fig. 7 illustrates another variant of the embodiment of the present subject matter. In case it is desirable to implement the Internal combustion (IC) engine (101) wherein, suitable attachments are provided to accommodate both detachable electric start system (301) and if desired detach the detachable electric start system (301) and insert the ISG. Further, the opening (305) on the first cover (203c) can be closed by a cap (341) having its outer contours matching to that of the opening (305). The oil gasket (307) is disposed between the cap (341) and the opening (305) and rigidly sealed with the aid of fasteners (342) on the plurality of mounting slots (345) on the crankcase assembly (203). Further, the plurality of mounting slots (345) is provided to enable ease of attachment and detachment of the electric start system (301). Hence, with this arrangement, the internal combustion (IC) engine (101) can be used interchangeably to implement both electric start system and ISG system. Whenever, ISG system is desired to installed, the detachable electric start system (301) can be removed and covered with the cap (341).
[00033] Referring to Fig. 8 and Fig. 9, these figures illustrate details of the second embodiment wherein an ISG-Internal combustion (IC) engine (101) comprises the ISG system in use to start the internal combustion (IC) engine (101). As discussed, the detachable electric start system (301) is not required in these cases, and the ISG-Internal combustion (IC) engine (101) can be assembled without the need of expensive design modifications and by just replacing the one way clutch (302) and ring gear (303) and covering the opening (305) with a cap (341), one can manufacture the Internal combustion (IC) engine with the ISG system which is another important advantage of the present subject matter. Some components of the ISG-Internal combustion (IC) engine (101) can vary; however, where components of this embodiment are the same as embodiment previously described, they have been identified by the same reference numerical to facilitate easy understanding of the different embodiments. Fig. 8. illustrates an isometric view of an Internal combustion (IC) engine (101) comprising a spacer (320) mounted on the crankshaft (304) according to an embodiment of the present subject matter. The Internal combustion (IC) engine (101) also comprises of an integrated starter generator (ISG) which can perform the functions of both magneto coil assembly during operation to recharge a battery (not shown) and as a starter when the Internal combustion (IC) engine (101) is attempted to be started. During assembly, as illustrated in Fig. 9 the spacer (320) is inserted to the right side of the crankshaft (304) replacing the width on the crankshaft (304) occupied by the one-way clutch (303) and the ring gear (302) if the detachable electric start system (301) was used.
[00034] The methodology for the manufacture and assembly of the internal combustion (IC) engine (101) in order to fully realize the present subject matter during manufacturing can be envisaged as follows. The process for manufacture and assembly is started at the assembly line for manufacture of the internal combustion (IC) engine (101). Initially, during assembly a decision is made to manufacture Internal combustion (IC) engine (101) having electric start system or ISG system. For manufacturing of the internal combustion (IC) engine (101) with electric start system, the one-way clutch (303) and ring gear (302) is inserted into the crankshaft (304) projecting from the rest of the crankcase assembly (203) before the first cover (203c) is assembled. After the sub-assembly of the one-way clutch (303) and the ring gear (302), the first cover (203c) is inserted and assembled on the crankcase assembly (203) and the right side of the crankshaft (304). Now, the detachable electric start system (301) is assembled on the upper portion of the first cover (203c) and mounted over the opening (305). If ISG mode system is to be assembled in the internal combustion (IC) engine (101), the spacer (320) is inserted into the right side of the crankshaft (304) projecting from the rest of the crankcase assembly (203) before the first cover (203c) is assembled. Further, the ISG system is mounted on the LH side of the crankshaft (not shown). After the sub-assembly of the spacer (320), a crankshaft nut (313) is inserted on the right side of the crankshaft (304) to lock the spacer (320) on the crankshaft (304). Later the first cover (203c) is now inserted and assembled to cover the exposed crankcase assembly (203) and the right side of the crankshaft (304). Further, the cap (341) is inserted to cover the opening (305) and prevent it from exposure. Fasteners (342) are used to secure the cap (341) over the opening and prevent any contaminants from entering the crankcase assembly (203) and also prevent any lubricating oil from leaking outside. The internal combustion (IC) engine (101) assembly is completed as no further starting system is required to be assembled.
[00035] Another related embodiment can be envisaged in light of the above subject matter. During assembly of the first cover (203c), the opening (305) portion need not be subjected to machining operation to accommodate the detachable electric start system (301), and further threaded holes need not be drilled further avoiding machining operation. Hence, during manufacturing of the Internal combustion (IC) engine, the first cover (203c) which is manufactured by casting process, the additional machining process of making opening (305) and drilling the holes for putting the fasteners can be avoided at this stage and only those first cover (203c) is sent for assembly in the internal combustion (IC) engine (101) for employing ISG system.
[00036] Many modifications and variations of the present subject matter are possible in the light of above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.
,CLAIMS:We claim:
1. An internal combustion (IC) engine (101) comprising:
a crankcase assembly (203) enclosing a crankshaft (304) and comprising one or more crankcase covers (203c, 203d) includes at least a first cover (203c); and
an electric start system (301) comprising:
an electric motor (301a) configured to transmit drive to said crankshaft (304) during starting of said internal combustion (IC) engine (101); and
an intermediate gear (501) operably connected to said electric motor (301a), and operably meshed with said crankshaft (304) through said opening (305);
said first cover (203c) configured to detachably mount said electric start system (301).
2. The internal combustion (IC) engine (101) as claimed in claim 1, wherein the electric start system (301) further comprises an electric motor output drive (505) emerging from the electric motor (301a), the intermediate gear (501), an idler shaft (504), a bush (506), and a motor sheath (301b), wherein the intermediate gear (501) mounted on the idler shaft (504) and configured to obtain drive from the electric motor output drive (505).

3. The internal combustion (IC) engine (101) as claimed in claim 1, wherein the electric start system (301) is inserted and mounted such that, the electric motor output drive (505) is enveloped by the motor sheath (301b) and is capable of meshing with the intermediate gear (501).

4. The internal combustion (IC) engine (101) as claimed in claim 1, wherein the intermediate gear (501) comprises of two sets of gear portions (501a & 501b) with different set of teeth located adjacent to each other. The second gear portion (501b) is meshed with the electric motor output drive (505) while the first gear portion (501a) is meshed with the ring gear (302).

5. The internal combustion (IC) engine (101) as claimed in claim 1, wherein the part of the intermediate gear (501) which is exposed is configured to mesh with the ring gear (302) mounted on the crankshaft (304).

6. The internal combustion (IC) engine (101) as claimed in claim 1, wherein said electric start system (301) is configured to be detachably attached to said crankcase assembly (203) through an opening (305) formed therein, said opening (305) on the crankcase assembly (203) is covered with a cap (341) when the electric start system (301) is detached, said cap (341) matching the exact contours of the opening (305).

7. The internal combustion (IC) engine (101) as claimed in claim 6, wherein said cap (341) mounted on a plurality of mounting slots (345) on the crankcase assembly (203).

8. The internal combustion (IC) engine (101) as claimed in claim 1, wherein the intermediate gear (501) is an idler gear (501).

9. A crankcase assembly (203) enclosing:
a crankshaft (304);
a ring gear (302) freely mounted to said crankshaft (304) and attached to a one-way clutch (303); and
said one-way clutch (303) securely mounted on said crankshaft (304) to transmit motion to said crankshaft (304);
wherein a spacer (320) having width equal to that of said ring gear (302) and said one-way clutch (303), said ring gear (302) and said one-way clutch (303) are replaced by said spacer (320) when said electric start system (301) is detached.

10. A method for assembling an internal combustion (IC) engine (101) comprising:
detaching an electric start system (301) mounted through an opening (305) provided on a first cover (203c) of a crankcase assembly (203) of said internal combustion (IC) engine (101);
replacing a ring gear (302) and a one-way clutch (303) mounted within said crankcase assembly (203) by a spacer (320) having width equal to that of the ring gear (302) and the one-way clutch (303);
closing said opening (305) of said crankcase assembly (203) by a cap (341), said cap (341) matching the exact contours of the opening (305) provided on said first cover (203c) of the crankcase assembly (203); and
mounting an ISG system within said crankcase assembly (203) of said Internal combustion (IC) engine (101) for employing ISG system.