Claims:We Claim,
1. A crankshaft (160) for an internal combustion engine (100), said internal combustion engine (100) comprising:
a cylinder head cover (105);
a cylinder head (110);
a cylinder block (115);
a reciprocating piston (215) enclosed in said cylinder block (115), a connecting rod (220);
a crankcase (165); and
a crankshaft (160) housed and rotatably supported by said crankcase (165);
wherein,
said crankshaft includes an opening (320) and said crank case includes a threaded orifice (325) for assembling a locking mechanism (400) comprising a locking tool (405);
wherein,
said locking tool includes an external thread (415), an extended pin (425);
2. The crankshaft (160) as claimed in claim 1, wherein, said locking mechanism (400) locks said crankshaft (160) at a specific position with reference to said reciprocating piston (215) at a TDC position (AA).
3. The crankshaft (160) as claimed in claim 1, wherein, said opening in said crankshaft (160) is parallel to a crankshaft axis YY’.
4. The crankshaft (160) as claimed in claim 1, wherein, said opening (320) has an offset center from said crankshaft (160) center.
5. The crankshaft (160) as claimed in claim 1, wherein, said threaded orifice (325) in said crankcase (165) is parallel and concentric to said opening (320) in said crankshaft (160) when said crankshaft (160) is in the position where said reciprocating piston (215) is in a TDC position AA.
6. The crankshaft (160) as claimed in claim 1, wherein, said extension pin (425) in said locking tool (405) locks to said crankshaft (160) via said opening (320). , Description:TECHNICAL FIELD
[0001] The present invention relates generally to an internal combustion engine. More particularly, the present invention relates to a crankshaft employed in the internal combustion engine of the two wheeled vehicle.

BACKGROUND
[0002] An internal combustion engine converts thermal energy obtained from burning of a fuel with an oxidizer (air) into mechanical energy, which can be used to do some kind of mechanical work. It is used in a wide range of applications including providing motive force for movement of a vehicle. The main parts of the engine include a cylinder head, a reciprocating piston on a cylinder block and a connecting rod which connects the piston to the reciprocating crankshaft. The connecting rod in the engine transfers power generated by the reciprocating piston in the cylinder block of the engine and converts it into rotary motion of the crankshaft together forming a slider crank mechanism. In a two wheeled vehicle having a single cylinder, the crankshaft usually comprises of a crankshaft left-hand side and crankshaft right-hand side assembled on either side of the connecting rod big end. A crankpin is inserted between the connecting rod big end and the crankpin is connected by the crankshaft right-hand side and crankshaft left-hand side together forming the crankshaft assembly. Generally, in two wheeled vehicles (including motorcycles and scooters) having single cylinder engine, the crankshaft assembly is of split type configured to be divided into right-hand side and left-hand side. Further, generally, each of the right-hand side and left-hand side of the crankshaft has a right crank web and a left crank web forming counterweights. The crankwebs weights are used as reciprocating masses to improve crankshaft balance and counter the reaction force due to crankshaft rotation. Typically, crankwebs of a single cylinder two wheeled vehicle is of circular cross section.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0004] Fig. 1. illustrates the side view of a two wheeled vehicle employing an embodiment of the present subject matter.
[0005] Fig. 2. illustrates the isometric view of the internal combustion engine employing the embodiment of the present subject matter.
[0006] Fig. 3. illustrates the cross sectional view of the internal combustion engine illustrating an oil cleaner assembly according to the embodiment of the present subject matter.
[0007] Fig. 4. illustrates the isometric view of the crankshaft and connecting rod according to the embodiment of the present subject matter.
[0008] Fig. 5. illustrates the exploded view of the crankshaft illustrating the oil cleaner assembly according to the embodiment of the present subject matter.

DETAILED DESCRIPTION
[0009] Generally, when the piston is at Top Dead Centre (TDC) position, the valves will be in closed condition. Therefore, there is no load on the camshaft. It is important that while removing camshaft from the engine there should not be any load acting on the camshaft especially the valve spring load (valve-opened condition). Also, while assembling the camshaft, the piston is to be set in the TDC position. Further, the camshafts are used to open and close the inlet and exhaust valves of the engine at the right time, with the exact stroke and in a precisely defined sequence. Assembly of camshaft angle in relation to the crankshaft angle will lead to valve timing error. Therefore, the present invention provides a Locking mechanism for the crankshaft on an internal combustion engine that is used to arrest the rotation of the crankshaft and to lock the crankshaft at a specific angle when engine is disassembling or servicing.
[00010] As per an embodiment of the present invention, the locking mechanism is used to lock the crankshaft at a specific position where piston is at the TDC position. Hence, the locking mechanism as disclosed in the present invention prevents wrong assembly of camshaft angle relative to crankshaft angle. Furthermore, while removing the parts like magneto and primary gear that are fastened to the crankshaft, the position of the crankshaft can be in any direction but the rotation of the crankshaft should be locked. As per an embodiment of the present invention, the locking mechanism is not only used for locking the crankshaft at a specific position where the piston is at TDC, but also to lock the rotation of the crankshaft. In one of the embodiment, the locking mechanism is used to lock the engine parts like magneto, Primary gear that fastened to the crankshaft, while disassembling or servicing. As per an embodiment, the locking mechanism is used to prevent rotation of the crankshaft while applying torque to remove the above said engine parts from crankshaft.
[00011] Accordingly, as per one of the embodiments of the present invention, an opening is provided in the crankshaft. In one of the embodiment, the opening in the crankshaft is parallel to the crankshaft center. Further, in one embodiment of the present invention, a threaded orifice is placed in the crankcase. As per an embodiment of the present invention, the threaded orifice in the crankcase is parallel and concentric to the opening in the crankshaft when the crankshaft is in the position where the piston is in the TDC position. Furthermore, as per an embodiment of the present invention, a locking tool is provided. In one of the embodiment the locking tool is inserted into the crankcase to lock into the opening in the crankshaft. The locking mechanism as discussed in the present invention is used for locking the crankshaft at a specific position where the piston is at the TDC position and to lock the rotation of the crankshaft while engine is dismantling or servicing. As per an embodiment of the present invention, the locking mechanism is implemented in a single cylinder internal combustion engine with an overhead camshaft.
[00012] In one of the embodiment, the crankshaft is assembled to a crank case of the internal combustion engine. As per an embodiment of the present invention the crankshaft is assembled on the crank case in between two bearings. Further, in one of the embodiment a connecting rod assembled to the crankshaft with bearing is provided. Accordingly, as per an embodiment of the present invention, a piston of the internal combustion engine is mounted to the connecting rod through a piston pin. Furthermore, the internal combustion engine includes a magneto (generator) rotor assembled to the crankshaft via connecting means such as a bolt, fastened to the crankshaft. As per an embodiment of the present invention a key is provided to stop relative motion between magneto rotor & crankshaft. In one of the embodiment of the present invention, the internal combustion engine includes a primary gear assembled to the crankshaft through splines. As per an embodiment, the primary gear is attached to the crankshaft via attaching means such as bolts. Furthermore, the internal combustion engine includes an intake camshaft and an exhaust camshaft for opening and closing the inlet and exhaust valves. As per an embodiment the intake and exhaust valves of the internal combustion engine are opened and closed at a pre-determined time, with the exact stroke and in a precisely defined manner. In one of the embodiment, the intake camshaft and exhaust camshaft are driven by the crankshaft via timing chain.
[00013] In one of the embodiment, the locking tool prevents the rotation of the crankshaft to remove the nut from crankshaft, while removing the magneto. As per an embodiment, the locking tool further prevents the rotation of the crankshaft for the disassembly of the primary gear. Further, while removing the camshaft from the internal combustion engine the piston has to be set at TDC position (valve- closed condition), to eliminate the valve spring load on camshaft at valve-opened condition. Furthermore, in one of the embodiment the locking mechanism locks the crankshaft at specific angle that aids to set the piston at the TDC position.
[00014] As per an embodiment of the present invention, the locking tool includes external thread followed by an extension pin, to lock the crankshaft. In one of the embodiment, the crankshaft has the opening on the crankshaft web that is parallel to the axial direction of the crankshaft. As per one embodiment, the opening has an offset center from crankshaft center. Furthermore, in one of the embodiment, said crank case consists of the threaded orifice that is parallel and concentric to the hole in the crankshaft when the crankshaft is at specific position where the piston is at the TDC position. As per an embodiment of the present invention a threaded cap closes the threaded orifice during engine running condition. According to one embodiment, while disassembling or servicing the engine parts during engine-off condition, the locking tool is inserted to the threaded orifice in the crank case and locked on to the matting thread in the crank case; simultaneously the pin extension in the locking tool will lock to the crankshaft to arrest the rotation of the crankshaft or to set the piston at the TDC position.
[00015] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder. According to an embodiment, an internal combustion (IC) engine described here operates in four cycles. The IC engine is installed in a two wheeled vehicle. It is pertinent to note that the IC engine may be mounted in two wheeled vehicles in different arrangements such as in transverse and longitudinal fashion. It is contemplated that the concepts of the present invention may be applied to other types of vehicles such as saddle-type, straddle-type within the spirit and scope of this invention. Further "front" and "rear", and "left" and "right" referred to in the ensuing description of the illustrated embodiment refer to front and rear, and left and right directions as seen from a rear portion of the IC engine and looking forward. The detailed explanation of the constitution of parts other than the present invention which constitutes an essential part has been omitted at suitable places.
[00016] Typically, in a two wheeled vehicle, an internal combustion (IC) engine having cylinder is located below a fuel tank at a lower rear portion of the vehicle. The IC engine, among other components, has a cylinder block comprising a cylinder head atop or in front of the cylinder block and receiving a reciprocating piston from the bottom or the rear. On combustion of the air-fuel mixture, the piston transfers the energy generated during combustion to a crankshaft through a connecting rod thereby driving the crankshaft. In this way, the reciprocatory motion of the piston is converted to rotatory motion of the crankshaft. The crankshaft is housed inside a crankcase beneath or behind the cylinder block. In order to set the vehicle into motion, the power supplied to the crankshaft of the internal combustion engine is carried to a wheel of the vehicle, in a controllable way, through a transmission system.
[00017] Conventionally, while removing camshaft from the engine there is a load acting on the camshaft especially the valve spring load (valve-opened condition). Also, while assembling the camshaft, the piston is to be set in the TDC position. Further, the camshafts are used to open and close the inlet and exhaust valves of the engine at the right time, with the exact stroke and in a precisely defined sequence. Assembly of camshaft angle in relation to the crankshaft angle will lead to valve timing error. Hence, the present invention proposes a Locking mechanism for the crankshaft on an internal combustion engine that is used to arrest the rotation of the crankshaft and to lock the crankshaft at a specific angle when engine is disassembling or servicing.
[00018] With the above proposed invention, the following advantages can be obtained such as locking the crankshaft at a specific position where the piston is at TDC and to lock the rotation of the crankshaft while engine is dismantling or servicing. The proposed locking mechanism prevents the wrong assembly of camshaft angle relative to crankshaft angle. Furthermore, while removing the parts like magneto and primary gear that are fastened to the crankshaft, the position of the crankshaft can be in any direction but the rotation of the crankshaft should be locked. As per an embodiment of the present invention, the locking mechanism is not only used for locking the crankshaft at a specific position where the piston is at TDC, but also to lock the rotation of the crankshaft. The assembly of the locking mechanism during manufacturing and assembly is simple and can be performed by simple operations such as lock tool fitting in the opening. Further, this helps in reducing cost and weight with minimum modifications in the existing designs significantly.
[00019] 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.
[00020] Fig. 1 illustrates the isometric view internal combustion (IC) engine (100) in accordance with one embodiment of the present invention. As per an embodiment of the present invention, said IC engine (100) transfers the drive directly to the rear wheel (no shown) as it is coupled directly to it. The IC engine (100) comprises a continuously variable transmission (CVT) system, said CVT system disposed leftward of the IC engine (100) in the vehicle width direction. The IC engine (100) is made up of a cylinder head cover (105), cylinder head (110), cylinder block (115), and a crankcase (165). A crankshaft (160) is disposed transversely with respect to the longitudinal cylinder axis.
[00021] Fig. 2 illustrates a cross-sectional view of said IC engine (100) in accordance with one embodiment of the present invention. As per an embodiment of the present invention, said IC engine (100) comprises a reciprocating piston (215) enclosed in said cylinder block (115), a connecting rod (220) connecting the reciprocating piston (215) to said rotatable crankshaft (160). Said cylinder head (110) is disposed over said cylinder block (115) forming a combustion chamber (not shown) at the junction. During operation, the burning of fuel and oxidizer occurs in said combustion chamber (not shown) and transfers mechanical energy to said reciprocating piston (215). Further, said reciprocating piston (215) transfers the mechanical energy to said crankshaft (160) which generates power. Furthermore, said cylinder head (110) comprises of at least one inlet valve (not shown) and at least one outlet valve (not shown) which are operated by means of rocker arms (not shown) and a camshaft (not shown) 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 (not shown) is meshed between said crankshaft (160) and said camshaft in order to drive said camshaft in said cylinder head (110). The inlet air fuel mixture from a throttle body (not shown) is connected to an inlet port of said IC engine (100) in said cylinder head (110) and an exhaust system including a muffler (not shown) is connected to the exhaust port of said cylinder head (110).
[00022] As per an embodiment of the present invention, said crankshaft (160) is housed and rotatably supported by said crankcase (165) on either side. Accordingly, in one of the embodiment, said reciprocating piston (215) of said internal combustion engine (100) is mounted to said connecting rod (220) through a piston pin (not shown). Furthermore, said internal combustion engine (100) includes a magneto (generator) rotor assembled to said crankshaft (160) via connecting means such as a bolt, fastened to said crankshaft (160). As per an embodiment of the present invention a key (not shown) is provided to stop relative motion between magneto rotor and said crankshaft (300). In one of the embodiment of the present invention, said internal combustion engine (100) includes a primary gear assembled to said crankshaft (160) through splines. As per an embodiment, said primary gear is attached to said crankshaft (160) via attaching means such as bolts. Furthermore, said internal combustion engine (100) includes an intake camshaft and an exhaust camshaft for opening and closing the inlet and exhaust valves. As per an embodiment the intake and exhaust valves of said internal combustion engine (100) are opened and closed at a pre-determined time, with the exact stroke and in a precisely defined manner. In one of the embodiment, said intake camshaft and exhaust camshaft are driven by said crankshaft (160) via said cam-chain (not shown).
[00023] In one of the embodiment, said crankshaft (160) is assembled to said crank case (165) of said internal combustion engine (100). As per an embodiment of the present invention, a locking mechanism (400) is used to lock said crankshaft (160) at a specific position where said reciprocating piston (215) is at a TDC position (AA). Hence, said locking mechanism (400) as disclosed in the present invention prevents wrong assembly of camshaft angle relative to crankshaft angle. As per an embodiment of the present invention, said locking mechanism (400) can also lock the rotation of said crankshaft (160). In one of the embodiment, said locking mechanism (400) is used to lock other parts of said internal combustion engine (100), such as magneto, Primary gear that are fastened to said crankshaft (160), while disassembling or servicing. As per an embodiment, said locking mechanism further prevents rotation of said crankshaft (160) while applying torque to remove the above parts of said internal combustion engine (100) from said crankshaft (160).
[00024] Fig. 3 illustrates the exploded view of said crankshaft (160) of said IC engine (100) employing the embodiment of the present invention and housed in said crankcase (165). Accordingly, as per one of the embodiments of the present invention, an opening (320) is provided in said crankshaft (160). In one of the embodiment, said opening in said crankshaft (160) is parallel to the crankshaft axis YY’. Further, in one embodiment of the present invention, a threaded orifice (325) is positioned in said crankcase (165). As per an embodiment of the present invention, said threaded orifice (325) in said crankcase (165) is parallel and concentric to said opening (320) in said crankshaft (160) when said crankshaft (160) is in the position where said reciprocating piston (215) is in the TDC position AA. As per an embodiment, said reciprocating piston (215) has movement along a piston axis XX’. Furthermore, as per an embodiment of the present invention, said locking mechanism (400) includes a locking tool (405). In one of the embodiment said locking tool (405) is inserted into said crankcase (165) to lock into said opening (320) in said crankshaft (160). Said locking mechanism (400) as discussed in the present invention is used for locking said crankshaft (160) at a specific position where the piston is at the TDC position AA and to lock the rotation of said crankshaft (160) while engine is dismantling or servicing.
[00025] As per an embodiment, said locking tool (405) further prevents the rotation of said crankshaft (160) for the disassembly of the primary gear. Further, while removing said camshaft from said internal combustion engine (100) said reciprocating piston (215) has to be set at TDC position AA(valve-closed condition), to eliminate the valve spring load on camshaft at valve-opened condition. Furthermore, in one of the embodiment said locking mechanism (400) locks said crankshaft (160) at specific angle that aids to set said reciprocating piston (215) at said TDC position AA.
[00026] As per an embodiment of the present invention, said locking tool (405) includes an external thread (415) followed by an extension pin (425), to lock said crankshaft (160). In one of the embodiment, said crankshaft (160) has said opening (320) on the crankshaft web that is parallel to the axial direction of said crankshaft (160). As per one embodiment, said opening (320) has an offset center from said crankshaft (160) center. Furthermore, in one of the embodiment, said crank case (165) consists of said threaded orifice (325) parallel and concentric to said opening (320) in said crankshaft (160) when said crankshaft (160) is at specific position where said reciprocating piston (215) is at the TDC position AA. As per an embodiment of the present invention a threaded cap (not shown) closes said threaded orifice (325) during engine running condition. According to one embodiment, while disassembling or servicing the engine parts during engine-off condition, said locking tool (405) is inserted in to said threaded orifice (325) in said crank case (165) and locked on to said crank case (165); simultaneously said extension pin (425) in said locking tool (405) will lock to said crankshaft (160) to arrest the rotation of said crankshaft (160) and to set said reciprocating piston (215) at said TDC position AA.
[00027] 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.

List of Reference Numerals:
100 Internal Combustion Engine
105 Cylinder Head Cover
110 Cylinder Head
115 Cylinder Block
160 Crankshaft
165 Crank case
215 Reciprocating Piston
220 Connecting rod
320 Opening on Crankshaft
325 Threaded Orifice in crankcase
400 Locking Mechanism
405 Locking Tool
415 External Thread on Locking Tool
425 Extension Pin
XX’ Piston Axis
YY’ Crankshaft Axis
AA TDC Position