Claims:WE CLAIM:
1. An engine assembly (100) for a motor vehicle (10), comprising:
a crankcase (110);
an oil sump (120) provided in a bottom region of the crankcase (110);
an oil pump (130) for transmitting oil from the oil sump (120) to one or more locations within the crankcase (110);
a gearbox (140) disposed inside the crankcase (110), the gearbox (140) having a plurality of gears;
an oil jet (150) for dispersing oil received from the oil pump (130); and
a guide member (160) for receiving the oil from the oil jet (150) and guiding the oil on the gears thereby lubricating the gears.

2. The engine assembly (100) as claimed in claim 1, wherein the oil jet (150) is positioned in the crankcase (110) such that it receives a part of the oil travelling in a channel between the oil sump (120) and a piston jet.

3. The engine assembly (100) as claimed in claim 1 or 2, wherein the crankcase (110) comprises a protrusion (112) having a hole provided for directing a part of the oil travelling in the channel between the oil sump (120) and the piston jet towards the oil jet (150).

4. The engine assembly (100) as claimed in claim 3, wherein the protrusion (112) is provided in a right-side portion of the crankcase (110).

5. The engine assembly (100) as claimed in claim 3, wherein the protrusion (112) is provided substantially above an opening (114) in the crankcase (110) for receiving a crankshaft.

6. The engine assembly (100) as claimed in claim 1, comprising a breather circuit (170) wherein the guide member (160) is substantially separated from an outer wall (172) of the breather circuit (170) to form a passage for oil from the oil jet (150) to fall on the gears.

7. The engine assembly (100) as claimed in claim 6, wherein an outlet (150B) of the oil jet (150) is disposed in the vicinity of the outer wall (172) of the breather circuit (170).

8. The engine assembly (100) as claimed in claim 7, wherein a first end (160A) of the guide member (160) is disposed below the outlet (150B) of the oil jet (150) thereby allowing the oil from the oil jet (150) to fall on to the guide member (160).

9. The engine assembly (100) as claimed in claim 1, wherein a second end (160B) of the guide member (160) is disposed above a transverse horizontal plane (X-X’) connecting a clutch shaft (142) of the gearbox (140), a drive shaft (146) of the gearbox (140) and the crankshaft, thereby allowing oil from the guide member (160) to fall on to the gears.

10. The engine assembly (100) as claimed in claim 1, wherein the second end (160B) of the guide member (160) is disposed substantially between a first longitudinal vertical plane (Y-Y’) passing through a crankshaft central axis and a second longitudinal vertical plane (Z-Z’) passing through a clutch shaft (142) central axis.

11. The engine assembly (100) as claimed in claim 9 or 10, wherein direction of oil flowing from the guide member (160) is along a direction of rotation of the clutch shaft (142), thereby allowing the oil from the guide member (160) to lubricate the gears.
, 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, especially saddle-type vehicles, gearbox is generally lubricated by a splash lubrication mechanism in which oil taken up from an oil sump by moving components is splashed around the gearbox in uncontrolled manner. In this type of lubrication mechanism, quantity of oil in the oil sump and orientation of the components in the engine assembly plays a vital role. As such, dependence of the mechanism on the volume of oil in the oil sump does not ensure efficient lubrication of the gearbox in all conditions. Further, the amount of oil being delivered to the gearbox is also critical. A greater than desired amount of oil increases drag loss in the gearbox and lower than desired amount of oil will result in uneven lubrication. Also, if the lubrication oil is of poor quality, the splash lubrication becomes furthermore ineffective.
[003] As mentioned before, the efficiency of splash lubrication is also dependent on orientation and size of the engine. For smaller sized engines of saddle-type vehicles, generally a dedicated lubrication mechanism for the gear box is not employed as they run at lesser torque and at lower temperature levels. For larger sized engines of saddle-type vehicles, which are operated at higher torque levels and temperature levels, a dedicated gearbox lubrication mechanism becomes important to ensure adequate lubrication for the gearbox to prevent long-term damage to the gearbox and ensure the smooth functioning and transitioning of the gear ratios of the gearbox.
[004] However, even in smaller sized engines, in certain running conditions, due to improper or harsh usage of the gearbox, for instance, continuous usage of a particular gear ratio at non-optimum RPMs instead of smoothly transitioning between various gear ratios depending on the engine RPM, leads to deterioration of the components of the gearbox and increases gearbox temperatures, which resultantly leads to damaging of the gearbox as splash lubrication mechanism does not ensure adequate lubrication of the gearbox.
[005] Thus, there is a need in the art for an engine assembly for a motor vehicle which addresses at least the aforementioned problems.

SUMMARY OF THE INVENTION
[006] In one aspect, the present invention is directed to an engine assembly for a motor vehicle. The engine assembly has a crankcase, an oil sump provided in a bottom region of the crankcase, an oil pump for transmitting oil from the oil sump to one or more locations within the crankcase, a gearbox having a plurality of gears disposed inside the crankcase, an oil jet for dispersing oil received from the oil pump, and a guide member for receiving the oil from the oil jet and guiding the oil on the gears thereby lubricating the gears.
[007] In an embodiment of the invention, the oil jet is positioned in the crankcase such that it receives a part of the oil travelling in a channel between the oil sump and a piston jet. Herein, the crankcase has a protrusion having a hole provided for directing a part of the oil travelling in the channel between the oil sump and the piston jet towards the oil jet.
[008] In another embodiment of the invention, the protrusion is provided in a right-side portion of the crankcase.
[009] In a further embodiment of the invention, the engine assembly has a breather circuit wherein the guide member is substantially separated from an outer wall of the breather circuit to form a passage for oil from the oil jet to fall on the gears.
[010] In a further embodiment of the invention, an outlet of the oil jet is disposed in the vicinity of the outer wall of the breather circuit.
[011] In another embodiment of the invention, a first end of the guide member is disposed below the outlet of the oil jet thereby allowing the oil from the oil jet to fall on to the guide member.
[012] In a further embodiment of the invention, a second end of the guide member is disposed above a transverse horizontal plane connecting a clutch shaft of the gearbox, a drive shaft of the gearbox and the crankshaft, thereby allowing oil from the guide member to fall on to the gears.
[013] In a further embodiment of the invention, the second end of the guide member is disposed substantially between a first longitudinal vertical plane passing through a crankshaft central axis and a second longitudinal vertical plane passing through a clutch shaft central axis.
[014] In a further embodiment of the invention, direction of oil flowing from the guide member is along a direction of rotation of the clutch shaft, thereby allowing the oil from the guide member to lubricate the gears.

BRIEF DESCRIPTION OF THE DRAWINGS
[015] 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 illustrates a side view of an exemplary motor vehicle, in accordance with an embodiment of the invention.
Figure 2 illustrates a side sectional view of an engine assembly in accordance with an embodiment of the invention.
Figure 3 illustrates a perspective sectional view of the engine assembly in accordance with an embodiment of the invention.
Figure 4 illustrates the side sectional view of the engine assembly in accordance with an embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION
[016] 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 providing a dedicated lubrication to a gearbox.
[017] 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 110 (shown in Figure 2). In an alternative embodiment, the IC engine 12 is mounted horizontally (not shown) with the cylinder block extending horizontally forwardly from the crankcase 110. In an embodiment, the cylinder block is disposed rearwardly of the down tube.
[018] 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 33 is disposed at the end of the motor vehicle 10 and at the rear of the seat assembly 18. A grab rail 35 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.
[019] 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.
[020] Figure 2 illustrates a side 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 the crankcase 110 having an opening 114 for housing a crankshaft (not shown). The crankshaft is driven by a crank mechanism (not shown) 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 has a central axis about which it rotates. In an embodiment, the IC engine 12 is a single cylinder engine, and one connecting rod is connected to one crankpin of the crankshaft.
[021] As further illustrated in Figure 2, the engine assembly 100 has an oil sump 120 provided in a bottom region of the crankcase 110, and an oil pump 130 for transmitting oil from the oil sump 120 to one or more locations in the crankcase 110 through various oil paths. The oil in its path, reaches various locations in the crankcase such as a cylinder head (not shown), one or more exhaust and intake valves (not shown) etc. from the oil sump 120 by means of the oil pump 130, and after lubricating the various engine parts, for example the reciprocating piston, and one or more exhaust and intake valves etc., returns to the oil sump 120.
[022] As further illustrated in Figure 2, the engine assembly 100 has a gearbox 140 which is disposed inside the crankcase 110 and the gearbox 140 has a plurality of drive gears 144 and driven gears 148. In that, the gearbox 140 has a clutch shaft 142 (shown in Figure 3) rotatably coupled with the crankshaft. The plurality of drive gears 144 are mounted on the clutch shaft 142. The gearbox 140 further has a drive shaft 146 (shown in Figure 3), on which the plurality of driven gears 148 are mounted, which mate with the plurality of drive gears 144, hence transmitting the crankshaft rotation to the drive shaft 146 via the clutch shaft 142. The drive shaft 142 is further connected to a drivetrain that transmits the rotation of drive shaft 142 to the wheels for driving the motor vehicle 10.
[023] As illustrated in Figure 3, and referenced in Figure 2, to provide a dedicated lubrication channel for the gearbox 140, the engine assembly 100 has an oil jet 150 for dispensing the oil received from the oil pump 130 towards the gearbox 140. The engine assembly 100 further has a guide member 160 for receiving the oil exiting the oil jet 150 and guiding the oil towards the gearbox 140, thereby providing a dedicated lubrication for the gearbox 140 and lubricating the gears.
[024] In an embodiment of the invention, to transmit the oil from the oil sump 120 to the oil jet 150, the oil jet 150 is positioned in the crankcase 110 such that the oil jet 150 receives a part of the oil that is travelling in an existing oil channel from the oil sump 120 to a piston jet (not shown). The existing oil channel from the oil sump 120 to the piston jet, transmits the oil for lubrication of reciprocating piston wherein the piston jet receives the oil from the oil sump 120 and delivers the oil to the reciprocating piston. The part of the oil traveling in this oil channel between the oil sump 120 and the piston jet, is directed towards the oil jet 150 for lubricating the gearbox 140. In an embodiment of the invention, the directing of the oil towards the oil jet 150 from the oil channel between the oil sump 120 and the piston jet is facilitated by a protrusion 112 in the crankcase 110, with the protrusion having a hole therein. The protrusion 112 is disposed in the crankcase 110 such that it diverts a portion of the oil towards the oil jet 150 through the hole. In this embodiment, an inlet 150A of the oil jet 150 is provided in the hole of the protrusion 112 in the crankcase 110, such that the oil so deflected by the protrusion 112, is received by the inlet 150A of the oil jet 150 through the hole. In an embodiment, the protrusion 112 in the crankcase 110 is provided on a right-side portion of the crankcase 110.
[025] In an embodiment of the invention as illustrated in Figures 2 and 3, the protrusion 112 in the crankcase 110, having the hole, is provided substantially above the opening 114 in the crankcase 110 for receiving the crankshaft.
[026] As further illustrated in Figure 3, and referenced in Figure 2, the engine assembly 110 further has a breather circuit 170 to remove unwanted gases, called as blow-by, from the crankcase 110. The guide member 160 is provided in the engine assembly 100 in a manner that the guide member 160 is substantially separated from an outer wall 172 of the breather circuit 170. This forms a passage for oil from the oil jet 150 to fall on to the gears, which is defined between the outer wall 172 of the breather circuit 170 on an upper side and the guide member 160 on a lower side. Herein, the guide member 160 runs substantially parallelly to the outer wall 172 of the breather circuit 170 and hence further defining the passage, for the oil to fall on to the gears. In an embodiment of the invention, an outlet 150B of the oil jet 150 is disposed in the vicinity of the outer wall 172 of the breather circuit 170, thereby allowing the oil from the outlet 150B of the oil jet 150 to be received by a first end 160A of the guide member 160, wherein the first end 160A is disposed below the outlet 150B of the oil jet 150 thereby allowing the oil from the oil jet 150 to fall on to the guide member 160.
[027] Figure 4 illustrates the side sectional view of the engine assembly 100. As can be seen in Figure 4, illustrated by arrows in the Figure, the oil enters the inlet 150A of the oil jet 150 from the protrusion 112 in the crankcase 110, and exits the oil jet 150 at the outlet 150B of the oil jet 150. The oil is then received by the first end 160A of the guide member 160, and the oil travels along the guide member 160, exiting the guide member 160 at a second end 160B. The oil from the second end 160B of the guide member 160 then falls on to the gearbox 140 lubricating the gears. The oil thus falling on the gearbox 140 lubricates mating surface of the drive gears 144 and the driven gears 148. In an embodiment of the present invention, to allow for the oil exiting the guide member 160 to fall on to the gearbox 140, the second end 160B of the guide member 160 is disposed above a transverse horizontal plane (X-X’) connecting the clutch shaft 142 of the gearbox 140, the drive shaft 146 of the gearbox 140 and the crankshaft 110, which results in oil from the guide member 160, assisted by gravity, to fall on to the gears. In a further embodiment, the second end 160B of the guide member 160 is disposed substantially between a first longitudinal vertical plane (Y-Y’) passing through the crankshaft central axis and a second longitudinal vertical plane (Z-Z’) passing through a clutch shaft 142 central axis about which the clutch shaft 142 rotates in operation, thereby ensuring that the oil exiting the second end 160B of the guide member 160, falls on to the gearbox 140.
[028] To further facilitate lubrication of mating surface of the drive gears 144 and driven gears 148, in an embodiment of the invention, direction of oil flowing from the guide member 160 is along a direction of rotation of the clutch shaft 142, thereby allowing the oil from the guide member 160 to travel to mating surface of drive gears 144 and driven gears 148 assisted by the rotation of the drive gears 144 on the clutch shaft 142, and hence lubricating the mating surface of the drive gears 144 and driven gears 148. For instance, as illustrated in Figure 4, the oil is travelling in the depicted direction when the clutch shaft 142 is rotating in a clockwise direction, and hence the oil falling on to the drive gears 144 is carried to mating surface of the drive gears 144 and driven gears 148, lubricating the gearbox 140.
[029] Advantageously, the engine assembly of the present invention ensures a dedicated lubrication for the gearbox, resultantly ensuring that adequate oil is supplied to the gearbox for lubrication in all conditions. The dedicated lubrication ensures that the durability of the gearbox is increased even on harsh usage as long-term wearing down of the gears is reduced.
[030] Further, adequate lubrication also ensures better heat transfer properties in the gearbox, preventing overheating of the gearbox and prolonging the life of the gearbox. Furthermore, the engine assembly of the present invention can be accommodated in saddle-type vehicles having both smaller sized engines such as 100cc, 110 cc etc. and larger sized engines.
[031] 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.