Claims:WE CLAIM:
1. An engine assembly (100) for a motor vehicle, comprising:
a crankshaft (110) housed in a crankcase (120);
a cam chain window (130) through which an oil path passes from a cylinder head to an oil sump in the crankcase (120); and
an Integrated Starter Generator (ISG) (200) having a rotor (210) rotatably mounted on one end of the crankshaft (110), the rotor having a plurality of protrusions (212) on circumferential surface; wherein the circumferential surface of the rotor (210) receives oil from the cylinder head through the cam chain window (130) and the plurality of protrusions (212) splash the oil towards inner wall (122A) of a cover crankcase (122) adjacent to the ISG (200) thereby cooling the oil.

2. The engine assembly (100) as claimed in claim 1, wherein the rotor (210) is aligned with the cam chain window (130).

3. The engine assembly (100) as claimed in claim 1, comprising of a deflector positioned below the cam chain window (130) to direct the oil on to the circumferential surface of the rotor (210) of the ISG..

4. The engine assembly (100) as claimed in claim 1, comprising a bearing (140) mounted on the crankshaft (110); and a cam chain sprocket (150) sandwiched along the length of the crankshaft (110) between the bearing (140) and the ISG (200).

5. The engine assembly (100) as claimed in claim 1, wherein the crankcase (120) is downsized in a vehicle width direction.

6. An Integrated Starter Generator (ISG) (200) for a motor vehicle, the ISG comprising: a rotor (210) having a plurality of protrusions (212) on its circumferential surface and configured to be mounted on one end of a crankshaft (110).

7. The integrated Starter Generator (ISG) (200) as claimed in claim 6, wherein the plurality of protrusions (212) on the rotor (210) act as a crank-position sensing device.
, Description:FIELD OF THE INVENTION
[001] The present invention relates to an engine assembly for a motor vehicle.

BACKGROUND OF THE INVENTION
[002] In conventional motor vehicles, magnetos, also referred to as ignition magnetos, provide current to ignition system of a spark ignition engine. A magneto is a rotating auxiliary device in the nature of an electric generator with permanent magnets that produces periodic pulses of alternating current. In spark ignition engines, magneto provides pulses of high voltages to spark plugs.
[003] In these conventional motor vehicles consisting of a magneto, a starter motor is also required for cranking of the engine. For cranking the engine, the starter motor is connected to a ring gear mounted on a crankshaft for multiplying the torque input and an adjoining starter drive one way clutch to transmit the torque from the starter motor to the ring gear. The need for accommodating ring gear and starter drive one way clutch in addition to the magneto and the starter motor, leads to an extended length of the crankshaft and resultantly, a wider crankcase especially on the magneto side.
[004] In such conventional motor vehicles, the return path of the engine oil begins at cylinder head of the engine where the engine oil provides lubrication to the piston, and in some cases air and fuel valves, and terminates at an oil sump provided in the crankcase and passing through a window provided for the cam chain. While the departure path of the oil from the oil sump to the cylinder head is established through an oil pump, the return path is generally gravity assisted. The engine oil in the return path is cooled by the atmospheric air flowing over the crankcase.
[005] However, the oil return path in the conventional motor vehicles does not allow for an efficient cooling of the oil as the atmospheric air comes in contact with the outer surface of the crankcase, and in the traditional oil return paths, the oil path is distant from the outer surface of the crankcase while returning from the cylinder head to the oil sump.
[006] This not only affects the oil temperatures but also the engine performance as the oil operating at higher temperatures lose their lubrication properties over time and cannot provide the necessary heat exchange and lubrication at the cylinder head.
[007] This kind of conventional design also has a higher number of mechanical parts such as ring gear and starter drive one way clutch which leads to a higher overhang in crankshaft, resulting into more end deflection and noise.
[008] Also, the heating issues caused by such conventional designs may cause the engine oil to operate beyond the Toxic Air Contaminants (TACS) limit.
[009] Thus, there is a need in the art for an engine assembly which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[010] In one aspect of the invention, the present invention is directed to an engine assembly for a motor vehicle. The assembly has a crankshaft housed in a crankcase; a cam chain window through which an oil path passes from a cylinder head to an oil sump in the crankcase; and an Integrated Starter Generator (ISG). The ISG has a rotor rotatably mounted on one end of the crankshaft wherein the rotor has a plurality of protrusions on circumferential surface. The circumferential surface of the rotor receives oil from the cylinder head through the cam chain window and the plurality of protrusions splash the oil towards inner wall of a cover crankcase adjacent to the ISG thereby cooling the oil.
[011] In an embodiment of the invention, the rotor of the ISG is vertically aligned with the cam chain window.
[012] In another embodiment of the invention, the engine assembly has a deflector positioned below the cam chain window to direct the oil on to the circumferential surface of the rotor of the ISG.
[013] In another embodiment of the invention, the engine assembly comprises of a bearing mounted on the crankshaft, and a cam chain sprocket sandwiched along the length of the crankshaft between the bearing and the ISG. In an embodiment of the invention, the crankcase is downsized in a vehicle width direction.
[014] In another aspect of the invention, the present invention is directed to an Integrated Starter Generator for a motor vehicle. The ISG has a rotor having a plurality of protrusions on its circumferential surface, configured to be mounted on one end of a crankshaft.
[015] In an embodiment of the invention, the rotor of the Integrated Starter Generator the plurality of protrusions act as a crank-position sensing device.

BRIEF DESCRIPTION OF THE DRAWINGS
[016] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 shows an exemplary motor vehicle in accordance with an embodiment of the invention.
Figure 2 is a sectional view of an engine assembly for a motor vehicle in accordance with an embodiment of the invention.
Figure 3 shows an Integrated Starter Generator in accordance with an embodiment of the invention.
Figure 4 shows the Integrated Starter Generator in accordance with an embodiment of the invention.
Figure 5 is a sectional view of a part of the engine assembly for a motor vehicle in accordance with an embodiment of the invention.
Figure 6 shows a comparison between engine running temperature in conventional configuration versus engine running temperature in the current configuration in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[017] The present invention relates to an engine assembly for a motor vehicle. More particularly, the present invention relates to an engine assembly for a motor vehicle to provide efficient cooling of oil.
[018] Figure 1 illustrates an exemplary motor vehicle 10, in accordance with an embodiment of the invention. The motor vehicle 10 comprises an IC engine 12 that is vertically disposed. Preferably, the IC engine 12 is a single-cylinder type IC engine. The motor vehicle 10 comprises a front wheel 14, a rear wheel 16, a frame member, a seat assembly 18 and a fuel tank 20. The frame member includes a head pipe 22, a main tube 24, a down tube (not shown), and seat rails (not shown). The head pipe 22 supports a steering shaft (not shown) and two telescopic front suspensions 26 (only one shown) attached to the steering shaft through a lower bracket (not shown). The two telescopic front suspensions 26 support the front wheel 14. The upper portion of the front wheel 14 is covered by a front fender 28 mounted to the lower portion of the telescopic front suspension 26 at the end of the steering shaft. A handlebar 30 is fixed to upper bracket not shown and can rotate to both sides. A head light 32, a visor guard (not shown) and instrument cluster (not shown) is arranged on an upper portion of the head pipe 22. The frame member comprises a down tube that may be located in front of the IC engine 12 and extends slantingly downward from head pipe 22. The main tube 24 of the frame member is located above the IC engine 12 and extends rearward from head pipe 22. The IC engine 12 is mounted at the front to the down tube and a rear of the IC engine 12 is mounted at the rear portion of the main tube 24. In an embodiment, the IC engine 12 is mounted vertically, with a cylinder block extending vertically above a crankcase. In an alternative embodiment, the IC engine 12 is mounted horizontally (not shown) with the cylinder block extending horizontally forwardly from the crankcase. In an embodiment, the cylinder block is disposed rearwardly of the downtube.
[019] The fuel tank 20 is mounted on the horizontal portion of the main tube 24. Seat rails are joined to main tube 24 and extend rearward to support a seat assembly 18. A rear swing arm 34 is connected to the frame member to swing vertically, and the rear wheel 16 is connected to rear end of the rear swing arm 34. Generally, the rear swing arm 34 is supported by a mono rear suspension 36 (as illustrated in the present embodiment) or through two suspensions on either side of the motor vehicle 10. A taillight unit (not shown) is disposed at the end of the motor vehicle 10 and at the rear of the seat assembly 18. A grab rail (not shown) is also provided on the rear of the seat rails. The rear wheel 16 arranged below seat 18 rotates by the driving force of the IC engine 12 transmitted through a chain drive (not shown) from the IC engine 12. A rear fender 38 is disposed above the rear wheel 16.
[020] Further, an exhaust pipe 40 of the vehicle extends vertically downward from the IC engine 12 up to a point and then extends below the IC engine 12, longitudinally along the vehicle length before terminating in a muffler 42. The muffler 42 is typically disposed adjoining the rear wheel 16.
[021] Figure 2 illustrates a sectional view of an engine assembly 100 for a motor vehicle 10 in accordance with an embodiment of the invention. As illustrated, the engine assembly 100 has a crankshaft 110 housed in a crankcase 120. The crankshaft 110 is driven by a crank mechanism consisting of a series of crankpins attached to connecting rod of a piston to convert the reciprocating motion of the piston into rotational motion. The crankshaft 110 has a linear axis 112 about which it rotates. In the present embodiment, the IC engine 12 being a single cylinder engine, one connecting rod is connected to one crankpin of the crankshaft 110.
[022] As further illustrated in the figure, the engine assembly 100 further has a cam chain window 130. The cam chain window 130 is an aperture in the crankcase 120 provided to allow the connection of the crankshaft 110 to a camshaft via a cam chain. The camshaft driven by the crankshaft 110 operates intake and exhaust valves in the IC engine 12 via a plurality of cam pins. In the present invention, the return path of oil from a cylinder head of the IC engine 12 to an oil sump in the crankcase 120, is directed through the cam chain window 130. The oil in its departure path, reaches the cylinder head from the oil sump by means of an oil pump and after lubricating the reciprocating piston and exhaust and intake valves in the cylinder head, returns to the oil sump through the cam chain window 130.
[023] As further illustrated in the figure, the engine assembly 100 further has an Integrated Starter Generator (ISG) 200 mounted on one end of the crankshaft 110. As illustrated in Figure 3 and 4, the ISG 200 has a rotor 210 having a plurality of protrusions 212 on its circumferential surface, which rotates with a crankshaft 110, in the same axis 112 as the crankshaft 110. In an embodiment of the invention, the protrusions 212 on the rotor 210 act as a crank-position sensing device, wherein a crank position angle sensor (not shown) detects the position of the crankshaft 110 based on the rotation of the protrusions 212. The ISG is configured to provide torque to the engine 12 during cranking and harnessing the energy from the crankshaft 110 as a generator when the engine 12 is running. The ISG 200 is also configured to provide pulsating signals to spark plugs for ignition, thereby replacing a traditional magneto and starter motor configuration. The replacement of the magneto and starter motor configuration by the ISG 200 also negates the requirement of mechanical components such as a ring gear and starter drive one way clutch, which allows for the crankshaft 110 length to be reduced. In an embodiment of the invention, the crankshaft 110 length is reduced by up to 15-20 mm over the conventional configuration. Reduction in length of the crankshaft 110 has resulted in the reduction in the width of the crankcase 120 and thereby the engine assembly 100.
[024] Reference is made to Figure 2 wherein, the reduction of the crankshaft 110 length in the present invention allows for the oil in its return path from the cam chain window 130 assisted by gravity to fall on to the circumferential surface of the rotor 210. When the oil falls on to the circumferential surface of the rotor 210, the impingement of the oil on to the rotating protrusions 212 creates a splash effect owing to the break in the flow of the oil by the protrusions 212 and the centrifugal force imparted by the rotation of the rotor 210.
[025] The splash effect makes the oil splash outwards relative to the axis 112 of rotation of the crankshaft 110 and on to an inner surface 122A of cover crankcase 122 adjacent to the ISG 200. The falling of the oil on the circumferential surface of the rotor 210 and the subsequent splash effect has been depicted by arrows as illustrated in the figure. An outer surface 122B of said cover crankcase 122 is exposed to the atmospheric air, and as the vehicle is running, atmospheric air passes over the outer surface 122B of said cover crankcase 122. The travelling air meeting the outer surface 122B of said cover crankcase 122 thereby cools said cover crankcase 122 and resultantly, cools the oil coming in contact with the inner surface 122A of said cover crankcase 122. In an embodiment of the invention, said cover crankcase 122 is made of aluminium providing effective cooling of said cover crankcase 122 by the traveling atmospheric air.
[026] The oil that is cooled on being splashed on to the inner surface 122A of said cover crankcase 122 flows to the oil sump in the crankcase 120 assisted by gravity, hence completing its return path from where it can be pumped towards the cylinder head again by an oil pump.
[027] In an embodiment of the invention, the rotor 210 of the ISG 200 is vertically aligned with the cam chain window 130 such that the oil in its return path from the cam chain window 130 assisted by gravity directly falls on to the circumferential surface of the rotor 210.
[028] In an embodiment of the invention, the engine assembly 100 further has a deflector (not shown) positioned below the cam chain window 130 to direct the oil towards the circumferential surface of the rotor 210 with greater effectiveness to further enhance the splash effect.
[029] Figure 5 illustrates the engine assembly 100 in accordance with an embodiment of the invention. As illustrated, the engine assembly 100 further has a bearing 140 which supports the crankshaft 110 and allows rotation of the crankshaft 110 during the engine 12 operation. The engine assembly 100 further has a cam chain sprocket 150 which is a profiled wheel with cogs/ teeth which mesh with the cam chain. The cam chain sprocket 150 is coupled to the crankshaft 100 such that it rotates with the crankshaft 110 and thereby rotates the camshaft. In the present configuration, the cam chain sprocket 150 is sandwiched between the bearing 140 and the ISG 200 along the length of the crankshaft 110.
[030] Crankshaft overhang 160 is defined by the length of the crankshaft 110 between the cam chain sprocket 150 and the ISG 200. As illustrated in Figure 5, the present configuration allows for crankshaft overhang 160 to be minimised, which further reduces crankshaft 110 end deflection and thereby reducing noise, vibration and harshness while the engine is running.
[031] A smaller crankshaft overhang 160 also allows for the crankcase 120 to be downsized a vehicle width direction, meaning that the rider foot is further away from the crankcase 120, which creates a better air flow path for traveling atmospheric air and hence making the cooling even more efficacious.
[032] As illustrated in Figure 6, the engine 12 running temperature in the present configuration is substantially reduced as compared to the engine running temperature in conventional configurations. A temperature difference of as much as 3 degree Celsius can be achieved by the present invention, bringing the average engine 10 running temperature down from 110 degree Celsius to 107 degree Celsius.
[033] Advantageously, the present invention provides an engine assembly which allows for the crankshaft length to be reduced, allowing the rotor of the ISG to be aligned with the cam chain window and thereby allowing a more efficient cooling of the oil in its return path. Such efficient cooling of the oil prolongs the life cycle of the oil and improves engine performance by maintaining the engine operating temperature at a lower level, while also keeping the oil within the TACS limits.
[034] Further, the present configuration eliminates the requirement of additional mechanical elements such as the magneto, ring gear and one way clutch, reducing the crankshaft overhang and reducing the noise, vibration and harshness during engine running.
[035] The said cover crankcase in the present configuration is downsized when compared to a conventional cover crankcase covering the magneto, and hence the present configuration allows for a more compact engine and better air flow path for the traveling air providing more effective cooling.
[036] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.