DESC:TECHNICAL FIELD
[0001] The present invention generally relates to an internal combustion engine of an automobile. More particularly, the present invention relates to a system for measuring the output speed of the internal combustion engine.

BACKGROUND
[0002] Many factors affect an automobile safety, out of which speed is the most important factor as it gives the driver proper control of the automobile. Measuring the speed of the internal combustion engine is necessary, as the driver needs to be aware of the accurate speed in which the automobile is moving on the road enabling him to perform various operations and maneuvers. Additionally, automobile speed measurement is used as input data by controllers and/or electronic control unit to perform a wide variety of functions in automobile vehicle diagnostics control such as using speed governor devices, steering control, and control of braking systems. One such very important system where measurement of accurate vehicle speed is required is the working of automated manual transmission system.

BRIEF DESCRIPTION OF THE DRAWINGS
[0001] 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.
[0002] Fig. 1 illustrates the side view of a two wheeled vehicle according to an embodiment of the present invention.
[0003] Fig. 2a illustrates the side view of an internal combustion engine according to the embodiment of the present invention.
[0004] Fig. 2b illustrates the rear perspective view of an internal combustion engine according to the embodiment of the present invention.
[0005] Fig. 3a illustrates the cross-sectional view (X-X) of the internal combustion engine showing the output shaft along with the rotating member according to the embodiment of the present invention.
[0006] Fig. 3b illustrates the cross-sectional view (X-X) of the internal combustion engine with the AMT transmission system enlarged.
[0007] Fig. 4a illustrates the exploded view of the output shaft according to the embodiment of the present invention.
[0008] Fig. 4b illustrates the exploded view of the output shaft according to another embodiment of the present invention.
[0009] Fig. 5a illustrates the front view of the rotating member according to the embodiment of the present invention.
[00010] Fig. 5b illustrates the side view of the rotating member according to the embodiment of the present invention.

DETAILED DESCRIPTION
[00011] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder. In the ensuing exemplary embodiments, the vehicle is a two wheeled vehicle. However it is contemplated that the disclosure in the present invention may be applied to any automobile capable of accommodating the present subject matter without defeating the spirit of the present invention. The detailed explanation of the constitution of parts other than the present invention which constitutes an essential part has been omitted at suitable places.
[00012] Measuring the vehicle speed is necessary, as the driver needs to be aware of the accurate speed at which his automobile is running. This is especially important from the safety point of view as, knowledge of the vehicle speed will aid in keeping the automobile in control and help the driver to avoid excessive speed and dangerous turns, and as a requirement of governmental norms. Additionally, knowledge of accurate speed will help the driver to be aware at which speed, he can manually shift gear for greater fuel economy and efficiency. Additionally, accurate measurement of vehicle speed is required during internal combustion engine testing as a reference from which we calibrate the automobile and the internal combustion engine in order to meet governmental norms. Additionally, vehicle speed measurement is used as input data by controllers to perform a wide variety of functions in automobile vehicle diagnostics control such as using speed governor devices, steering control, and control of braking systems. One such very important system where measurement of accurate vehicle speed is required is the working of automated manual transmission system.
[00013] A transmission system of an internal combustion engine is essential as it transmits rotary motion from the crankshaft to the wheel(s) to drive the automobile. Typically, the transmission system of the internal combustion engine includes transmission stages, drive shafts, and the final drive to the wheel(s). The AMT system is a transmission system that performs manual gear shifts automatically. This system eliminates the need of mechanical actuation of a clutch lever by the driver and eliminating the need to shift the gears manually. It uses various sensors, a controller unit and actuators to continuously control the operation of the clutch and manual gear shifts by the controller unit, based on various inputs received such as engine speed, gear position, clutch position, throttle position and vehicle speed. In this regard, the measurement of vehicle speed plays a critical role when the controller unit operates the AMT system.
[00014] Generally, the vehicle speed is measured by a system that comprises of a signal generating mechanism and a signal-receiving device to generate a signal to be transmitted to the signal-receiving device. The vehicle speed is sensed by the signal-receiving device, is usually a controller unit which has various processors, input/output interface devices and memory block which use the vehicle speed data to perform many of the functions. The signal generating mechanism has usually one or more sensors which is an electronic unit which works on the principle of Hall Effect or other similar arrangement, and comprises a signal generator mounted in close proximity of the actual sensing portion which generates the signal. The sensor works on the principle of sensing alternating ridge patterns and its frequency of occurrence. It is a well-known concept to employ a toothed wheel or gear having equiangular spaced teeth on the shaft to be measured in conjunction with a fixed sensor to provide a pulse train output signal to the controller unit as the toothed wheel rotates.
[00015] Measurement of vehicle speed is essential in the AMT system because there are lot transmission losses when the rotary motion from the crankshaft is ultimately transmitted to the wheel(s). Hence, in order to effectively perform seamless and effective automatic transmission, measurement of accurate vehicle speed is a must. This factor needs to be taken into account while calculating when to perform gear shifts in the AMT system. Although vehicle speed can be measured at any convenient location beyond the crankshaft of the internal combustion engine, it is desirable to measure the vehicle speed at the output shaft of the internal combustion engine, as it provides an accurate measurement of vehicle speed eliminating all the transmission losses. The final drive between the output shaft and the wheel(s) can be a chain drive with the gearing ratio between the sprockets known. Since, the chain drive is a positive drive with minimal transmission losses, the vehicle speed can be calculated by knowing the gear ratio and the value measured as the engine speed at the output shaft.
[00016] In a two wheeled vehicle, such as a motorcycle for example, the internal combustion engine is very compact, and has components that are compactly arranged with little space available for any additional elements. Additionally, the transmission system used in such two wheeled vehicle is a constant-mesh type gear transmission system. In such limited layout, the output shaft forms a part of the driven shaft of such a constant-mesh gear transmission system. In such a layout, it is required to measure the vehicle speed by measuring the speed of the output shaft. Since, sensors work by detecting alternating ridge patterns; it is ideal to locate the speed sensor in the crankcase that measures the sliding gear in the output shaft. Such sliding gear forms part of the constant-mesh type gear transmission system. Since, the sliding gear is movably attached to the output shaft through the external splines in the output shaft; the speed of the sliding gear will give accurate measurement regarding the speed of the vehicle. However this arrangement has a major drawback that, the sliding gear slides linearly while shifting gears. This sliding gear travel at the extreme travel position causes a signal loss in the sensor. Since, the sensors is positioned perpendicularly with respect to the sliding gear and is stationary, the gear travel from one extreme position to another extreme position may move out of the sensor range, resulting in signal loss. Since, the AMT system is designed to shift gears automatically, this signal loss may result in detection of wrong signals by the controller unit which assumes there is reduction in vehicle speed due to incorrect calculations. Subsequently, the controller unit incorrectly controls gear shift or clutch shift. This will cause the automobile to run at high torque at a substantially high speed which is undesirable and may cause an uncomfortable driving experience to the driver. Additionally, this sudden shift of gears to a lower gear may lead to dangerous situations where the two wheeled vehicle can become uncontrollable to the driver. When the sliding gear comes within sensing range of the sensor, accurate vehicle speed is detected by the sensor, then the AMT system shifts to a higher gear again and this improper shift of higher gear to lower gear and vice versa will prevent the two wheeled vehicle from running smoothly and provides an uncomfortable driving experience.
[00017] Conventionally, to measure the vehicle speed, the sensor is conveniently placed at any location where reliable speed measurements can be taken. A common location is locating the sensor in close proximity to the wheel(s). This is not desirable as accurate measurement is not possible. In order for accurate measurement the air gap between the sensor unit and the measuring element must remain clear of any contaminants. But locating the sensor in close proximity to the wheel(s), may subject the air gap to harsh atmospheric conditions such as dust, mud or water. These contaminants may give rise to inaccurate measurements. Hence, locating the sensor near the wheel(s) is undesirable. Placement of sensor in the certain other locations will also cause lot of signal errors. If the sensor unit is located in proximity of oil in the gearbox, it is subjected to fluctuations in oil temperature in addition to contamination of impurities in the air gap. Additionally due to smaller internal combustion engine layout, there are constraints, and due to compact nature of arrangement of the transmission system in the engine, there no additional space in the transmission shaft where sensor can be located. Another method to measure the vehicle speed of the output shaft is by introducing splines/serrations in the output shaft and locating the sensor to sense the rotation of such splines/serrations. But this has a major drawback that, there is a need to provide empty space in the output shaft by increasing its span length which is not desirable. As we increase the span length of the output shaft it causes layout constraints, increase costs and overall weight of the internal combustion engine.
[00018] The present invention has been devised in view of the above difficulties and it is therefore an object of the present invention to measure vehicle speed from the output shaft accurately and without any signal loss or signal error.
[00019] Another object of the present invention is to ensure least modification in the layout of the internal combustion engine.
[00020] Another object of the present invention is to is to facilitate mounting of sensor on the crankcase body of the internal combustion engine so that wiring routing for the sensor is simplified, avoiding unnecessary or excess looping.
[00021] Another objective of the present invention is to locate the sensor that will render it easy for assembling and servicing.
[00022] Another objective of the present invention is save cost and prevent increasing the weight of the system by using lighter materials such as plastic material.
[00023] Another object of the present invention is to propose a device as aforesaid which is simple in its construction, economical in use and effective in operation.
[00024] With the above design changes, the following advantages can be obtained such as accurate measurement with no signal loss, usage in AMT system and its output shaft and utilization of the small space to implement the present invention, use of any material possible, such as plastic material as long as the detecting area is made of metal, and can be designed such that, axial load to the output shaft does not affect the performance for measuring vehicle speed.
[00025] According to the present invention to attain the above mentioned objectives, there is provided a system for measuring revolutions of the output shaft of the internal combustion engine, said output shaft being configured to provide final output drive from the internal combustion engine. The system comprises one or more sensors, and the output shaft comprises a rotating member fixedly attached to the output shaft and capable of rotating with said output shaft. The rotating member is configured to enable said one or more sensors to measure the revolutions of the rotating member when the internal combustion engine is in operation. The rotating member further comprises a circular portion, a boss portion, and a flange portion. The circular portion comprises gear teeth profile disposed radially on the external circumferential surface of the circular portion. The boss portion has a semi-circular profile, said semi-circular profile is configured to receive the outer portion of the output shaft.
[00026] The present invention ensures that, the rotary member is fixedly attached to the output shaft. Hence, the one or more sensors is conveniently placed at the close proximity to the rotating member on the crankcase. When the output shaft rotates, the fixed rotary member also rotates; hence the speed sensor will measure the engine revolutions. The fixed rotary member ensures that, there is absolutely no signal loss since the rotary member remains fixed and does not travel linearly. This arrangement is also advantageous, as the rotary member is designed in such a way that, least portion of the shaft is utilized in the output shaft and no change required in the existing layout of the internal combustion engine. Additionally, there is least modification required in the output shaft. All these arrangements provide most accurate measurement of the output shaft revolutions and no signal loss is observed. This accurate output shaft revolution measurement ensures effectively working of all the devices that rely on this value. In one embodiment of the present invention, it is adopted in the AMT system, wherein the output shaft forms a part of the driven shaft of the AMT system, and the measured revolutions of said rotating member aids in the control of AMT system by providing effective, real time and accurate data. Additionally, this arrangement does not cause any change in existing layout and the output shaft further comprises a drive kick-starter gear which is freely mounted on said output shaft and disposed coaxially over the flange portion of the rotating member.
[00027] In the present invention, in order to measure the revolutions of the output shaft, said one or more sensors are located on a crankcase body of the internal combustion engine at a location in the crankcase which is in close proximity to the rotating member, and the crankcase body of the internal combustion engine has a hole and a boss to accommodate said one or more sensors.
[00028] The present invention 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.
[00029] Fig. 1 illustrates a two wheeled vehicle, having an AMT internal combustion engine (IC) (101) in accordance with one embodiment of the present invention. The two wheeled vehicle is a step through vehicle with an IC engine (101) connected below a U-shaped frame assembly. The U-shaped 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 supports (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) 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 (not shown). A handlebar (106) is fixed to steering shaft (not shown) and can rotate to both sides. The upper portion of the upper bracket (not shown) comprises of a visor assembly (124) which encloses the handlebar (106), mirror assembly (105) and instrument cluster (not shown). The down tube 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 from the step-through structure (117). A gusset (reinforcing plate) connects the head tube (102) with the down tube (107). The two wheeled vehicle further includes a rear wheel (113), a fuel tank (not shown), a pillion hand-rest (118) and seat (108). The Left and right rear swing arm bracket portions (not shown) is pivoted on the U-shaped frame assembly at the rear of the step-through structure (117), and supports the swing arm assembly. The swing arm assembly 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. Additionally, the swing arm assembly comprises of a front engine mounting cross tube (not shown), and a rear engine mounting cross tube (125) on which an IC engine (101) is swingably supported. The rear wheel (113) is connected to rear end of the swing arm assembly and configured to rotate by the driving force of the IC engine (101) transmitted through a chain drive (not shown) from the IC engine (101). Seat rails (not shown) are joined to the pair of side frame tubes (109) and stretch rearward to support a seat (108) disposed above seat rails (not shown). The rear wheel (113) located below seat (108) is rotated by the driving force of the IC engine (101) transmitted through a chain drive (not shown) from the 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).There is front brake (120) and back brake (114) arranged on the front wheel (119) and back wheel (113) respectively. The two wheeled vehicle also comprises of plurality of electrical and electronic components including a headlight (104), a taillight (112), a transistor controlled ignition (TCI) unit (not shown), a starter motor (not shown).
[00030] Fig. 2a illustrates the side view of the IC engine (101) in accordance with the embodiment of the present invention. The IC engine (101) is made up of a cylinder head assembly (201), cylinder block (202) and crankcase (203). The crankcase is made up of left-hand crankcase (203a) (hereafter LH crankcase) and right-hand crankcase (203b) (hereafter RH crankcase). The IC engine (101) also comprises of an integrated starter generator (ISG) (204) which can perform the functions of both magneto coil assembly during operation to recharge a battery (not shown) and as a starter when the IC engine (101) is attempted to be started. The IC engine (101) also has a sprocket (401) which is fixed to an output shaft (402) and capable of rotation when the IC engine (101) is in operation.
[00031] Fig. 2b illustrates the rear perspective view of the IC engine (101) in accordance with the embodiment of the present invention. The system for controlling AMT transmission comprises of a clutch actuation system (209), a gear actuation system (208), a clutch sensor (210), a magneto sensor pulsar coil (205), a gear sensor (not shown), a throttle sensor (not shown) located on the throttle body of the two wheeled vehicle and a vehicle speed measuring sensor (206). The clutch actuation system comprises of a clutch actuation motor (not shown), a movable rod (302a) and a means to control the movable rod (302a). The movable rod (302a) is operably connected such that, when the clutch actuation motor (not shown) is powered, it operates the movable rod (302a) and in turn engages or disengages a clutch (303). The clutch sensor (210) comprises of a sensor that detects the instantaneous clutch position and sends a signal to a controller unit (not shown). The controller unit (not shown) in turn based on such input from the clutch sensor (210) controls the clutch actuation motor (not shown). Additionally, there is a mechanically operated clutch lever (211) 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 (209), which is connected to a gear-shifting cam (not shown). The gear sensor (not shown) comprises of a sensor that detects the instantaneous gear position in the AMT system and sends a signal to a controller unit (not shown). The controller unit (not shown) in turn based on such input from the gear sensor (not shown) controls the gear actuation motor (209). According to one embodiment of the present invention, the speed sensor unit measures the speed of the output shaft according to the present invention. The speed sensor unit comprises of a speed sensor (601) and an outer body (206). The location of the speed sensor unit is configured to be located on the RH crankcase (203b) of the IC engine (101) with its outer body (206) attached to the RH crankcase (203b) surface. From the conventional state of art, this position of the speed sensor unit is shifted in order to be located in close proximity to a rotary member (501). Additionally, the speed sensor (601) is located perpendicular to the rotating member; and is supported by mounting flanges and bosses provided on the surface of the RH crankcase (203b). This entire sensor arrangement ensures that most accurate vehicle speed measurements can be taken.
[00032] Fig. 3a illustrates the cross-sectional view (X-X) of the IC engine (101) showing the main parts which include a reciprocating piston (306), a cylinder block (202), a connecting rod (307), an engine starting system (not shown) and the transmission system (301) controlled by the AMT system including the driven shaft of the AMT system being the output shaft (402) according to the embodiment of the present invention, which transmits rotary motion from the crankshaft (305) to the output of the IC engine (101). The connecting rod (307) converts the reciprocating motion of the piston (306) to the rotary motion of the crankshaft (305). The right side of the crankshaft (305) is coupled to the driving shaft (304) of the Transmission system (301) through the clutch (303). The clutch (303) is usually a multi-plate frictional clutch which works on the principle of multiple plates having frictional material lining meshing together to transmit rotary motion when engaged and plates separate when disengaged. The cylinder head assembly (201) comprises of at least one inlet valve (312) and at least one outlet valve (not shown) which are operated by means of rocker arms (not shown) and a camshaft (310) which consists of at least one inlet cam lobe (not shown) and at least one outlet cam lobe (not shown) which actuates the rocker arms (not shown) when required. A cam-chain (308) is meshed between gears (313) in the crankshaft (314) and camshaft (310) in order to drive the camshaft (310) in the cylinder head (201). The inlet air fuel mixture from the throttle body (not shown) is connected to an inlet portion of the IC engine in the cylinder head (201) and an exhaust system including a muffler (not shown) is connected to the outer portion of the cylinder head (201). The crankcase (203) houses the crankshaft (305), the Transmission system (301) and other ancillary systems which include lubrication system (not shown), cooling system (not shown) and exhaust system (not shown) all housed in the crankcase (203).
[00033] Fig. 3b. Illustrates the Transmission system (301) in the IC engine (101). In the present embodiment, the transmission system used is a synchronous constant mesh 5-speed gear box which comprises of a driving shaft (305) and a driven shaft (304) both shafts comprising of a plurality of geartrain mechanism designed to provide varying gear ratios. In the present invention the driven shaft (402) is the output shaft (402) where the rotating member (501) is placed. The driving shaft (305) is supported by two roller bearings (315 and 316) and the driven shaft (304) is also supported by two roller bearings (317 and 318) whose bearing outer surfaces are attached to the crankcase body thus providing good bearing support and supporting the axial loads of the driving and driven shafts. There are five gears disposed on the driving shaft (305) out of which three input gears (408a, 407a, 405a) are freely rotatable around the driving shaft (305), one input fixed gear (403a) is fixed and is an integral part of the driving shaft (305) and one driving axially mounted gear member (406a). The output shaft (402) comprises of three output gears (403, 406 and 404) are freely rotatable and axially restrained around the output shaft (402), and two driven axially mounted gear members (405 and 407). The axially mounted gear members on both driving shaft (304) and driven shaft (402) are controlled by shifting forks (not shown) which in turn is controlled by the gear-shift cam (not shown). The gear-shift cam (not shown) has guides on its surface and configured to guide the shifting forks (not shown) to move according to the rotation of the gear-shift cam (not shown). In the present invention, on every anticlockwise rotation of 60 degrees, one gear shift is incremented and every 60 degrees clockwise rotation, one gear shift is decremented. The gear shift actuation system controls this rotation of the gear cam (not shown) based on input of the controller unit (not shown).
[00034] Fig. 4a illustrates the exploded view of the output shaft (402) according to the embodiment of the present invention. The output shaft (402) comprises of two sections of splines (402a and 402b) to mount and enable axial movement of the two axially mounted gear member (405 and 407) controlled by the shift forks (not shown). There are internal splines (not shown) present on the inner surface of the axially mounted gear members (405 and 407) which exactly mate with the two external sections of splines (402a and 402b) on the output shaft (402). The other three output gears (403, 406 and 404) are freely mounted on the output shaft (402). They can either be mounted over roller bearings or mounted over the smooth surface of the output shaft (402). The rotating member (501) is mounted at the end of the output shaft (402) which is integrally mounted and axially restrained. The end of the output shaft (402) which has the rotating member (501), has a boss receiving portion 502c, said boss receiving portion (502c) having a first semi-circular profile (502b) flattened upto a depth of a certain distance. The first semi-circular profile (502b) is configured to receive the corresponding second semi-circular portion (502e) of the inner annular portion of the rotating member (501). The fitment is formed in such a way that, the flat portion of both the portions (502e and 502b) mate over each other and the circumferential round surface mates with the corresponding round surface of the inner periphery of the rotating member (501). The end portion of the output shaft (402), which mates with the rotating member (501) has a notch (502d) on the flat surface portion (502b), to locate two circlips (not shown) which provides additional attachment of the rotating member (501) and prevent the axial movement of the rotating member (501) during the output shaft (402) rotation. Fig. 4b illustrates the exploded view of another embodiment of the present invention, wherein a starter gear (408) is disposed between the first driven gear (408) and the rotating member (501). This starter gear (408) is used for assisting the IC engine (101) to start by cranking it by kick-starter mechanism (not shown).
[00035] Fig. 5a illustrates the front view of the rotating member (501) according to the embodiment of the present invention. The rotating member (501) in one embodiment comprises of a circular portion (501a), a boss portion (502a) and a flange portion (503). The circular portion (501a) comprises of in one embodiment plurality of gear tooth spaced radially around the outer circumferential surface of the circular portion (501a). Since, the speed sensor (601) works on the principle of sensing alternating ridge patterns and its frequency of occurrence, this gear tooth serves the above purpose. Fig. 5b illustrates the side view of the rotating member (501) showing the flange portion (503). The flange portion (503) comprises of a stepped flange located over one side of the flat side of the circular portion (501a). The flange portion (503) profile is so shaped, that it can accommodate another gear coaxially located over the flange portion (503). In another embodiment of the present invention, the starter gear (408) is disposed coaxially over the flange portion (503) of the rotating member (501) and freely mounted on the output shaft (402). The boss portion (502a) comprises of a almost circular portion with a slot cut out on it so as to form a flat surface in the direction perpendicular to the axis of rotation of the rotary member (501). This flat surface is configured to perfectly mate with the corresponding flat surface (502b) on one end of the output shaft (501). The second semi-circular portion (502e) of the inner periphery of the rotating member (501) also perfectly mates with the circular portion of the output shaft (501). Therefore, the overall arrangement is such that the slot formed in the boss portion (502a) perfectly mates with the flat surface (502b) provided in one end of the output shaft (402). The rotating member (501) is located on the output shaft (402) and its profile designed in such a way that there are absolutely no changes in layout required, such as modifications engine crankcase or providing a bigger output shaft or changing the location of roller bearings supporting the output shaft. Additionally, since the rotating member (501) is fixedly attached to the output shaft (402) and the function it performs is to provide measurements about output shaft speed to the speed sensor (601), the rotating member (501) can be advantageously made of any material such as plastic material or metal alloys as long as the gear teeth profile is metallic. Such a design helps reduce manufacturing cost, and reduces overall weight of the assembly.
[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 engine (101) comprising:
a crankcase (203);
a cylinder block (202) disposed on the crankcase;
a piston (306) reciprocating within the cylinder block (202);
a connecting rod (307) connecting the piston to a crankshaft (305), said connecting rod (307) converting the reciprocating motion to rotary motion of the crankshaft (305);
a transmission system (301) configured to vary the speed and torque output of the rotary motion generated by the crankshaft (305), said transmission system (301) comprising:
a driving shaft (304) configured to receive rotary motion from said crankshaft (305);
an output shaft (402) providing the output of the internal combustion engine (101);
a plurality of geartrain mechanisms mounted between the driving shaft (304) and the output shaft (402), said output shaft (402) comprising a plurality of output gears (403, 406, 404) configured to be axially restrained and freely mounted on the output shaft (402); and
a plurality of axially mounted gear members (405, 407) integrally mounted on the output shaft (402), said plurality of axially mounted gear members (405, 407) configured to be axially movable to enable the engagement one of plurality of geartrain mechanisms to vary the speed and torque output;
at least one speed sensor (601) disposed on the crankcase (203);
wherein,
said output shaft (402) comprising a rotating member (501) integrally mounted and axially restrained to the output shaft (402), and said rotating member (501) is configured to enable said at least one sensor (601) to measure the revolutions of the rotating member (501) when the internal combustion engine (101) is in operation.

2. The internal combustion engine (101) as claimed in claim 1, wherein said output shaft (402) forms a part of an automated manual transmission system, and wherein the measured revolutions of said rotating member (501) aids in the control of said automated manual transmission system.
3. The internal combustion engine (101) as claimed in claim 1 or claim 3, wherein the rotating member (501) comprising:
a circular portion (501a) including gear teeth profile disposed radially on the external circumferential surface of the circular portion (501a);
a boss portion (502a) disposed on the inner periphery of the rotating member (501), said boss portion (502a) comprising a second semi-circular profile (502e) disposed on its inner periphery, and said boss portion (502a) is configured to be securely mounted on the output shaft (402); and
a flange portion (503) disposed adjacent to the circular portion (501a), said flange portion (503) configured to coaxially receive a starter gear (408), said starter gear (408) configured to be freely mounted on the output shaft (402).
4. The internal combustion engine (101) as claimed in claim 1 or claim 3, wherein the output shaft (402) comprises a first semi-circular profile (502b) disposed on one end of the output shaft (402) and a sprocket (401) disposed on the other end of the output shaft (402), and a plurality of output gears (403, 406 and 404) form a part of the automated manual transmission system.
5. The internal combustion engine (101) as claimed in claim 1 or claim 4, wherein said boss portion (502a) is securely mounted on the output shaft (501) by inserting the boss portion (502a) on one end of the output shaft (402) whereby the first semi-circular profile (502b) on the outer periphery of the output shaft (402) is matched with the second semi-circular profile (502e) of the boss portion (502a) disposed on its inner periphery.
6. The internal combustion engine (101) as claimed in claim 1 or claim 5, wherein the boss portion (502a) is further secured when mounted on the output shaft (402) by a circlip inserted in the matching notches (502d) disposed on the outer periphery of the output shaft (402) and the inner periphery of the boss portion (502a).
7. The internal combustion engine (101) as claimed in claim 1 or claim 3, wherein the rotating member (501) is made up of plastic material and the gear teeth profile of the circular portion (501a) is made of metal alloy.
8. The internal combustion engine (101) as claimed in claim 1, wherein the internal combustion engine (101) comprises a left-hand crankcase (203a) and a right-hand crankcase (203b), said outer periphery of the right-hand crankcase (203b) comprising an outer body (206) mounted in close proximity to the rotating member (501) and providing access to the rotating member (501) disposed within the right-hand crankcase (203b), and said outer body (206) configured to accommodate said speed sensor (601) facing towards the rotating member (501) to measure the revolutions of the rotating member (501).
9. The internal combustion engine (101) as claimed in claim 1, wherein the driving shaft (304) comprises:
three input gears (408a, 407a, 405a) axially restrained and freely mounted to the driving shaft (304), said three input gears (408a, 407a, 405a) meshed with the third output gear (404), second axially mounted gear member (407) and first axially mounted gear members (405) respectively;
an input fixed gear (403a) axially restrained and securely mounted to the driving shaft (304), said input fixed gear (403a) meshed with the first output gear (403); and
a driving axially mounted gear member (406a) axially restrained and securely mounted to the driving shaft (304), said driving axially mounted gear member (406a) meshed with the second output gear (406).