AN INTERNAL COMBUSTION ENGINE WITH AUTOMATIC
TRANSMISSION

TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates generally to an internal combustion
engine, and more particularly, but not exclusively, to an internal combustion engine provided with automatic and manual transmission.

BACKGROUND OF THE INVENTION

[0002] Straddle type vehicles such as motorcycles generally have a
manual transmission system to carry the power generated by an internal combustion engine, in a controllable way, to a wheel of the vehicle. The manual transmission system comprises a system of interlocking gears such that by operating a gear shift lever manually, the driver can choose one of the several ratios of speed between the input shaft and the output shaft. To allow smooth and gradual shifting of gears, a clutch is provided to isolate the engine from the transmission momentarily. When the driver releases the clutch lever manually, the discs in the clutch assembly are squeezed with each other and thus the transmission is engaged with the engine.

[0003] . Automatic transmission (AMT) systems have come into use for
ease of operation of clutch actuation and gearshift. In these systems, the operation of gear shift and clutch actuation is solely accomplished by electronic means powered by a battery and controlled by a micro controller. Therefore, the ride on such vehicle is less tiring for the vehicle rider. However, in the event of

malfunction of the controller or during battery discharge or any other electrical fault, shifting of gears and clutch operation is disabled compromising the safety of the vehicle rider in certain conditions. These conditions include the riding of the vehicle on slope or while descending down from a hilly terrain.

BRIEF DESCRIPTION OF THE DRAWINGS
[0004] The present invention will now be briefly described with reference to the accompanying drawings in which:

FIG. 1 shows an isometric view of an AMT engine according to the present invention.

FIG. 2 shows an exploded view of the AMT engine of FIG. 1 according to the present invention.

FIG. 3 shows a detailed illustrative view of a clutch disengagement mechanism disposed internal to the AMT engine according to the present invention.
FIG. 4 shows a side view of the AMT engine in a condition with a transmission cover removed.

FIG. 5 shows a detailed exploded view of a gear shift mechanism disposed internal to the AMT engine according to the present invention.

FIG. 6 shows a sectional view of the crankcase of the AMT engine along an A-A axis of FIG. 4

FIG. 7 shows a side view of a crankcase right member of the AMT engine.

FIG.8 shows an isomteric view of a crankcase right member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] Conventionally, a fully automatic AMT engine has electrically
controlled clutch operation and gearshift operation. Due to this, the engine is not equipped to tackle any electrical failure issues. For example, it is probable that the vehicle may get stuck in the clutch engaged position. On occurrence of this event, the vehicle would come to a stop and it would not be possible for the driver, due to clutch engagement, to push the vehicle to the nearby service centre for vehicle check-up or maintenance to bring it into operable condition again. In another condition, the battery may be discharged completely thereby halting the electrical operations.

[0006] Therefore, it is fruitful to also have a manual control over the AMT
engine to ride through any unexpected electrical failure events, for example, when the vehicle is on upslope or while descending from the hilly areas. However, there are layout constraints in providing the option of manual control in an AMT engine because the engine has to accommodate various other components to make the manual control and automatic control feasible in one AMT engine. Further, while doing this, fouling between different components of engine is observed due to lack of space. Very close positioning of components may affect its proper working due to insufficient clearance between the components and lead to safety and reliability issues. The present invention tries to solve one or more problems and obviate a lacunae in the known art.

[0007] It is, therefore, an object of the present invention to provide an IC
engine having. an automatic and manually controllable gear shift and clutch

actuation without major design changes in the engine. Hence, the present invention discloses an AMT engine provided with a manual control of gear shift and clutch actuation. The manual components are assembled in the engine without major design changes so that the engine remains fully operational and can be operated manually during instances of electrical failure.

[0008] The invention is explained in detail by way of FIGs. 1 -8. It is to
be noted that "front" and "rear", unless mentioned otherwise, refer to front and rear directions as seen in a state of being seated on a seat of the vehicle carrying the present invention and looking forward. The vehicle is installed with the engine with its cylinder head facing towards the front. Further, "left" and "right", unless mentioned otherwise, refer to left and right directions of an onlooker standing in . front of the vehicle and looking towards it. A lateral axis refers generally to a side to side, or left to right axis relative to the vehicle. Various other features of the present subject matter here will be discernible from the following further description thereof, set out hereunder.

[0009] FIG. 1 shows an isometric view of an AMT engine, hereinafter
'engine' according to the present invention. The engine 1 comprises of a cylinder head 11, a cylinder head cover 12 and a cylinder block 13. The cylinder block 13 is coupled to a crankcase and the cylinder head is coupled to the cylinder block. In a horizontal engine like the one shown here, the cylinder head 11 is coupled to a front portion of the cylinder block 13. The cylinder head 11 is located forwardly of the cylinder block 13 and the crankcase is located rearwardly of the cylinder block 13, with the cylinder block 13 located between the cylinder head 11 and the

crankcase. FIG. 1 shows a horizontal type engine where the cylinder block 13 is forwardly titled and disposed in such a way that the long axis of the cylinder block 13 is approximately perpendicular to the longitudinal axis of a crankshaft 26 (shown in FIG.4). However, the concepts disclosed herein are equally applicable on a vertical engine where the cylinder block is vertical.

[00010] In an embodiment, the crankcase comprises of a crankcase left
member 14, and a crankcase right member 16 coupled to the crankcase left member 14. A transmission cover 18 is joined to the outer profile of the crankcase right member 16. It is located laterally to and adjacent to the engine 1 on a clutch side. A clutch actuation system and a gearshift actuation system are disposed internal to the AMT engine 1 supported on the crankcase and covered by the transmission cover 18. The transmission cover 18 also supports a gear shift motor 22 enabling gear shift actuation and a clutch actuation motor 20 for enabling clutch actuation electrically.

[00011] FIG. 2 shows an exploded view of the engine 1 showing the clutch
actuation system 30 and the gearshift actuation system 40 in detail. The clutch actuation system 30 actuates the clutch engagement and disengagement and comprises of a clutch 31 connected to the engine. The clutch actuation system 30 is both electrically and manually operable and is shown in further detail in FIG. 3. The clutch actuation system 30 includes the clutch actuation motor 20 with a -reduction gear box, a power transmission mechanism which transmits the rotational driving force of the clutch actuation motor 20 and a clutch position sensor 21 (shown in FIG.2) which detects the actuation of the clutch. The clutch

actuation motor 20 is mounted and secured to an outer surface of the transmission cover 18 and sealed against ingress of oil. It is electrically connected to a controller (not shown) which may be programmed to control the direction of . rotation of the clutch actuation motor 20 as well as the time duration of its operation.

[00012] The clutch 31 is electrically operated through the clutch actuation
motor 20 via the power transmission mechanism. In an embodiment, the power transmission mechanism comprises of a worm gear 32 operatively meshed with a worm wheel 33. The worm wheel 33 in turn is connected to an actuator plunger 36. In a preferred embodiment, the actuator plunger 36 is a circular structure engaged on its one side with the worm wheel 33 through a ramped ball mechanism, and on its other side with a clutch release pin (not shown). A plurality of ramped balls are caged in a ball carrying member 34 disposed between the actuator plunger 36 and worm wheel 33. In this way, the actuator plunger 36 takes rotational driving force from the worm wheel 33 through the ramped ball mechanism and operates the clutch release pin (not shown) thereby engaging and . disengaging the clutch 31 without any manual intervention. The clutch 31 is rotatably mounted on the clutch shaft 43 (shown in FIG.4) and works with the help of a clutch plate assembly through which it is engaged to and disengaged from a primary driven gear 44 taking its drive from a crankshaft 26 of the engine.

[00013] When the clutch actuation system for clutch disengagement fails
due to any reason by way of any electrical failure and the vehicle is stuck on road, the clutch is manually controlled manually which helps the rider to manually

disengage the automatic clutch. To this end, the clutch actuation system further comprises of a clutch release lever 24 operatively connected to the actuator plunger 36. The clutch release lever 24 rotatably operates a clutch release shaft 35b having an end portion 39 configured to engage with an engaging portion 37 of the actuator plunger 36. The engaging portion 37 of the actuator plunger 36 is extended centrally from one side of the actuator plunger 36 engaged with the clutch release pin. The engaging portion 37 engages with the end portion 39 of the clutch release shaft 35b. It also operates the clutch release pin when the need to manually disengage the clutch arises. The clutch release shaft 35b is preloaded by a return spring 35a to bring the clutch release shaft 35b to its original position after the withdrawal of manual force on the clutch release lever 24. One end of the return spring 35a is held on an inner surface of the transmission cover 18. The transmission cover 18 further supports the clutch release shaft 35b.

[00014] In an embodiment, the actuator plunger 36 and the clutch release
shaft 35b are operatively engaged through a rack and pinion, arrangement. The engaging portion 37 of the actuator plunger 36 comprises a rack and the end portion 39 of the clutch release shaft 35b comprises a pinion having a plurality of grooves that intermesh with the grooves of the rack. A guide-cum-holder member
38 having grooves is provided which partially covers and supports the end portion
39 and the engaging portion 37, and keeps them guided towards their intended path. It keeps the end portion 39 of the clutch release shaft 35b and engaging portion 37 of the actuator plunger 36 in contact with each other for transfer of input from the clutch release lever 24. The guide-cum-holder member maintains

the central distance between the rack and pinion arrangement of the clutch release shaft and the actuator plunger. It protects the mechanism from misalignment between the rack and pinion arrangement. It guides the plunger to move axially and also provides rigidity to the system. During the operation of the clutch actuation mechanism, the rotatory motion of the clutch release shaft 35b is converted to the axial motion of the actuator plunger 36.

[00015] The clutch release lever 24 is manually operable and is provided
external to the transmission cover 18 for ease of access to the rider of the vehicle. The clutch release lever 24 is rotatably connected to the clutch release shaft 35b. However, the extent of rotation of the clutch release lever 24 is predetermined. It rotates only to that extent as the axial movement required by the engaging portion 37 of the actuator plunger to operate the clutch release pin. In another embodiment, the clutch release lever 24 may' be operated by the rider of the vehicle through a cable connected to another lever placed in close proximity of the handle bar of the vehicle. Further, the actuator plunger 36, the clutch release shaft 35b, the guide-cum-holder member 38 are housed internal to the transmission cover 18. Thus, the same AMT engine has a clutch which can be electrically or manually controlled depending upon the requirement.

[00016] The crankcase also supports the gearshift actuation system 40
which is now explained. The gearshift actuation system 40 enables the power transmission from the gearshift motor 22 to a shift drum 25 (shown in FIG.6) to enable gear shifting from one gear ratio to other gear ratio. In an embodiment, this power transmission is carried through the use of gearing system comprising a set

of gears internal to a transmission cover 18 and supported on crankcase. FIG. 5 illustrates the gearshift actuation system 40. A drive gear 55 of the gear shift motor 22 drives an idler gear 56 in contact with driven gear 57 on the crank facing side. The driven gear 57 is sandwiched between the shift drum 25 and a star index 45 (shown in FIG.6). The star index 45 is located anterior to the driven gear 57 and is connected to the shift drum 25 through pins. The gear shift motor 22 is connected to the controller through which the motor is run in both directions. The extent of rotation of the star index 45 determines the extent of the gear shift. A stopper 47 is provided proximately to the star index 45 to keep the star index in the chosen position i.e. in the selected gear ratio. The stopper 47 is supported on the crankcase and is held interior to the transmission cover 18.

[00017] When the gearshift actuation system for shifting of gears fails due
to any reason by way of any electrical failure and the vehicle is stuck on road, the gearshift is controlled manually. To this end, the gearshift actuation system further comprises of a gearshift lever 41 supported on the crankcase left member 14, a gearshift shaft 42 connected to the gearshift lever 41, a gearshift arm 53 mounted on the gearshift shaft 42 and a pawl 51. The gearshift lever 41 is manually operable and turnably supports plurality of gears on parallel shafts in a gear box supported on the crankcase enabling selecting one of the several gear ratios. The gears are in constant mesh and free running when in neutral. The gearshift lever 41 drives the gearshift arm 53 connected to the star index 45 through the pawl 51. After the clutch is disengaged, the gearshift lever 41 eventually drives the shift drum 25 through the star index 45 thereby effecting a

gear shift and locks free running gears to their shaft. The rotatory motion of the gearshift arm 53 is converted into an axial motion through the pawl 51 which operates the star index 45. In an embodiment of the AMT engine, the gearshift lever 41 and the gearshift motor 22 are on the opposite side of the crankcase.
[00018] In an embodiment, the pawl 51 is located in the clearance between
the idler gear 56 and the star index 45.The star index 45 is thus manually rotatable and electrically rotatable.

[00019] FIG. 4 shows a side view of the AMT engine in a condition with
the transmission cover 18 removed wherein the crankcase right member 16 is visible. The gearshift actuation system is majorly supported on the crankcase right member. The shift drum axis is represented by the numeral 61 and the clutch shaft . by 43. The stopper 47 is supported on the crankcase right member 16 through a stopper boss 60 (shown in FIG.6). One end of the stopper 47 is received in the stopper boss 60 and is secured to it through a fastener 49 shown in FIG. 6. The stopper 47 is spring loaded so that it can be contained at its stopping position on the outer profile of the star index 45.

[00020] The stopper 47 is disposed so that the axis of the one end of the
stopper 47 is located above the shift drum axis 61. Acording, to an aspect, the stopper boss 60 is located between the vertical axis of the clutch shaft 43 and the long axis of the gearshift arm 53. Further, the crankcase right member 16 is protruded upwardly at a location above the axis of the clutch shaft 43. The protruded portion 23 is formed integrally with the crankcase right member 16 and its contour is integral with an outer contour 17 (shown in FIG.4) of the crankcase

right member 16. An uppermost tip of the protruded portion 23 lies along the straight line joining the axis of the idler gear shaft 58 and axis of the clutch shaft 43. The protruded portion 23 is curved and ensures that the stopper 47 during its operation is prevented from its contact with the boundary of the crankcase right member 16.

00021] FIG. 8 shows a perspective view of the crankcase right member
16. The crankcase right member 16 comprises of a shift drum opening 27 receiving and supporting the shift drum 25, a clutch shaft opening 46 receiving and supporting the clutch shaft 43 and a crankshaft opening 28 forwardly of the clutch shaft opening 46 receiving and supporting the crankshaft 26. The stopper boss 60 is formed integrally with the rest of the crankcase right member 16. The profile of the crankcase left member 14 is modified according to the crankcase right member 16 to ensure homogeneity.

[00022] To prevent fouling between different components of the AMT
engine 1 belonging to manual and electrical controls, the clutch 31 is laterally moved along the lateral axis of the engine. This ensures better clearance between different components and makes available space.

[00023] It will be appreciated that the present invention and its equivalent
thereof offers many advantages, including those which have been described forthwith. The present invention provided manual and electric control of the clutch actuation and gearshift actuation in a single AMT engine. The engine combines the functionality of an automatic control along with the safety of a

manual control in case of any undesirable event. It is extremely simple in construction and function and does not require any complex structures.

[00024] The present invention is thus briefly described. It will be obvious
that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as .would be obvious to one skilled in the art are intended to be included within the scope of the present invention.
[00025] 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

We claim:

1. An AMT engine (1) for a vehicle, said AMT engine (1) having a clutch
actuation system (30), a gear, actuation system (40), a crankcase
comprising a crankcase left member (14) and a crankcase right member
(16), the crankcase right member (16) comprising a stopper boss (60)
located between a vertical axis of a clutch shaft (43) and a long axis of a
gearshift arm (53),
wherein the crankcase right member (16) is protruded upwardly at a location above said axis of the clutch shaft (43) and having an uppermost tip lying along a straight line joining axis of an idler gear shaft (58) and an axis of the clutch shaft (43).
2. The AMT engine (1) as claimed in claim 1, wherein the crankcase right member (16) supports one end of a stopper (47) through the stopper boss (60).
3. The AMT engine (1) as claimed in claim 2, wherein the stopper boss (60) is formed integrally with the crankcase right member (16).
4. The AMT engine (1) as claimed in claim 1, wherein the crankcase right member (16) comprises a clutch shaft opening (46) for receiving and supporting the clutch shaft (43).
5. The AMT engine (1) as claimed in claim 4, wherein the crankcase right member (16) further comprises a shift drum opening (27) for receiving and

supporting a shift drum (25), and a crankshaft opening (28) for receiving and supporting a crankshaft (26).
6^ The AMT engine (1) as claimed in claim 5, wherein the crankshaft opening (28) is located forwardly of the clutch shaft opening (46).
7. The AMT engine (1) as claimed in claim 1, wherein the gear actuation system (40) comprises of a gearshift lever (41) supported on the crankcase . left member (14), a gearshift shaft (42) connected to the gearshift lever (41), a gearshift arm (43) mounted on the gearshift shaft (42) and a pawl (51) operating a star index (45).
8. The AMT engine (1) as claimed in claim 1, wherein the clutch actuation system (30) .comprises a clutch release lever (24), a clutch release shaft (35b), and an actuator plunger (36).
9. The AMT engine (1) as claimed in claim 8, wherein said clutch release shaft (35b) rotatably connected to the clutch release lever (24) is configured to engage with an engaging portion (37) of the actuator plunger (36). ■
10. The AMT engine (1) as claimed in claim 1 or claim 9, wherein the clutch
release lever (24) is adapted to be operated through a cable connected to a
lever placed in proximity of a handle bar of the vehicle.