DESC:TECHNICAL FIELD
[0001] The present subject matter described herein generally relates to an internal combustion engine for a vehicle. More specifically, the present disclosure relates to an improvement in cylinder sleeve of the internal combustion engine.
BACKGROUND
[0002] Typically, an internal combustion (IC) engine is a heat engine in which combustion of a fuel occurs in a combustion chamber. Due to the combustion of fuel, there is an expansion of the high temperature and high-pressure gases produced inside the combustion chamber which applies direct force on the piston. This force is then transmitted to a crankshaft by means of a connecting rod. The connecting rod is attached to the piston by a swivelling gudgeon pin. The gudgeon pin is disposed within the piston. The reciprocating motion of the piston is translated to rotational motion of the crankshaft. This helps in transforming chemical energy into useful kinetic energy which is used to propel or power the vehicle.
[0003] The internal combustion engine comprises of a valvetrain, the piston, a piston rings, the crankshaft, a crankpin bearing and an oil pump. The interaction between the above-mentioned components is necessary for smooth functioning of the IC Engine. However, this interaction results in constant metal contact between the above parts leading to mechanical friction losses due to relative motion between the parts. The internal combustion engine has a low mechanical efficiency because of large number of reciprocating components. This also leads to lesser fuel efficiency. Therefore, the IC engine requires proper lubricating and cooling system to prevent friction between moving parts.
BRIEF DESCRIPTION OF DRAWINGS
[0004] The detailed description of the present subject matter is described with reference to the accompanying figures. Same reference signs are used throughout the drawings to reference like features and components.
[0005] Figure 1 exemplarily illustrates a perspective view of a cylinder block in accordance with the present invention.
[0006] Figure 2 exemplarily illustrates a perspective view of a cylinder block in accordance with the present invention.
[0007] Figure 3 exemplarily illustrates a perspective view of a cylinder block in accordance with the present invention.
[0008] Figure 4 exemplarily illustrates an exploded view of an IC engine in accordance with an embodiment of the present subject matter.
[0009] Figure5a and 5b exemplarily illustrates the graphical representation between a clearance provided by one or more slot and crank angle in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION OF THE INVENTION
[00010] Typically, an Internal Combustion (IC) Engine converts the reciprocating motion of a piston created by combustion of fuel into rotatory motion. When the force of combustion is greatest, some of the force pushes the piston against a cylinder wall. This friction results in energy loss. In a conventional IC engine, a central axis of a cylinder coincides with a central axis of a crankshaft. In other words, the piston in the IC engine is pushed down by the explosive force of combustion in a combustion chamber and this is the origin of the drive force created by the IC engine. However, the piston is not actually pushed straight downward or orthogonal to the sliding axis of the piston but the forces act at angle or has an angular or diagonal component acting on it. Although it is small, there is, in fact, a diagonal component to a downward force causes the piston to be pushed against the walls of the cylinder. This results in friction and a corresponding amount of horsepower loss. This friction-induced power loss can be reduced by lengthening the connecting rod, but lengthening the connecting rod makes the IC engine heavier and larger overall which is often undesirable for compact vehicles like straddle type two and three wheeled vehicles.
[00011] To solve this problem, an offset cylinder or a crank offset is provided. Herein, “offsetting” of the cylinder from the crankshaft is accomplished by providing the connecting rod and the piston with an offset distance away from the centre of the crankshaft. This aids in reduction of side forces being applied on the cylinder walls. Further, the losses occurring due to mechanical friction are also decreased thereby using the energy produced in the engine more effectively. The offset cylinder ensures several benefits like less weight, more compactness, lesser friction losses, less vibration, lesser side forces acting on the cylinder wall and higher fuel economy.
[00012] In conclusion, increasing the length of the connecting rod reduces the amount of friction between the piston and the cylinder wall but it makes the engine heavier and bulkier. A shorter connecting rod produces more friction loss. But providing an offset cylinder or crankshaft offset, enables both reduced loss and a more compact engine design.
[00013] However, while providing the desired crankshaft offset, there is reduction in the dynamic working clearance between the connecting rod and a cylinder sleeve or cylinder liner. In order to achieve a higher offset which can compensate undesirable angular forces and reduce friction, one way is to increase the bore diameter of the sleeve which is undesirable for a compact engine design. Increasing length of the crankshaft with less or no offset is also undesirable for a compact engine layout design. Thus there is a challenge to design a compact engine with a small size of connecting rod with offset while still overcoming low clearance with the cylinder sleeve..
[00014] Typically, a piston rattling noise, vibration, and a piston slap noise occur where a piston skirt contacts a cylinder bore due to piston motions within the cylinder bore. The piston ratting noise and the piston slap noise are high frequency forces that drives the cylinder sleeve/ liner and the engine block to vibrate and radiate impulsive noise. The piston slap noise is also transferred from the piston to the connecting rod and the crankshaft, and finally to the engine block. Moreover, the piston slap causes cylinder liner cavitation erosion with the induced excessive liner vibration. Therefore, if the clearance between the connecting rod and the cylinder liner is less, then the engine can get damaged quickly.
[00015] The above-mentioned problem may be overcome by decreasing the length of the cylinder liner snout area depending on the cylinder bore and stroke of the IC engine. However, the reduction in length of liner surface will lead to malfunctioning of the piston, increased noise and vibration, and increased thermal problems. Further, decreasing the cylinder liner surface will make the cylinder liner prone to deformation due to high pressure and temperature inside the cylinder thereby causing a leakage of compressed gas and combustion gas. Furthermore, the decrease in the cylinder liner surface will lead to more friction with the piston ring and more consumption of lubricating oil. Since, the IC engine cylinder wall needs to endure high temperature and high-pressure condition due to compression and combustion of fuel and gases, and the piston and piston ring together, are sliding at a high speed, the cylinder liners are carefully designed to provide high burn resistance, low friction with the piston/piston ring and low lubricating oil consumption demands.
[00016] Therefore, there is a need of providing an improved design of the IC engine offering enhanced dynamic clearance between the cylinder liner/sleeve and the connecting rod. The enhanced dynamic clearance between the cylinder liner/sleeve and the connecting rod allows for a higher crank offset without compromising with functionality of the IC engine.
[00017] As per an aspect of the present invention, one or more cut out is provided at the cylinder liner/sleeve surface. The one or more cut-out feature improves the dynamic clearances and leads to avoidance of the functional failure of the parts present in the IC engine. The one or more cut out, further, reduces the mechanical friction and side thrust of the piston/piston ring since the crankshaft offset is accommodated effectively. As per an aspect of the present invention, the cut-out or relief provided on the cylinder sleeve is aligned towards the lateral movement of the connecting rod with reference to the sliding axis of the piston such that the connecting rod during dynamic stroking movement can enter the relief or cut-out thereby enabling higher offset and / or higher working clearance between the connecting rod and the cylinder sleeve. Provision of the one or more cut out enables increased working clearance between various parts of the IC engine which enhances the performance of the IC engine for reasons cited earlier. Further, the durability of the IC engine increases because there is less wear and tear between the various parts of the IC engine.
[00018] Generally, the major engine components are installed in the IC engine block. The components installed in the IC engine, including the cylinder bores, are machined very precisely. The components must be thick enough to contain the pressure of the burning fuel mixture. A tight fit must be ensured between the cylinder base and the piston rings to enable the piston rings to seal the combustible gas. The cylinder walls are machined to provide a very smooth finish. Special grinding stones produce small grooves in the cylinder walls, which collect oil. These grooves help to lubricate the piston ring and the piston skirt.
[00019] Cylinder liner or the cylinder sleeve is a thin-walled hard metal cylinder inserted into a cylinder block of an engine and in which the piston runs. The cylinder liner/ cylinder sleeve is made in the shape of the cylinder barrel having a flange at the top. The flange keeps the cylinder liner/ cylinder sleeve in position in the cylinder block. The cylinder liner/ cylinder sleeve fits accurately in the cylinder. The perfect contact of the cylinder liner/ cylinder sleeve with the cylinder block is necessary for the effective cooling of the cylinder liner/ cylinder sleeve. Also, the gas pressure, piston thrust and impact loading during combustion are resisted by the combined thickness of the cylinder liner/ cylinder sleeve and the cylinder of the IC engine.
[00020] As per an aspect of present invention, the cylinder liner/ cylinder sleeve has one or more cut-out or relief. The dynamic clearance between the connecting rod and the cylinder sleeve is improved by one or more cut-out. Further, the one or more cut out provides the dynamic clearance when there is higher crank-offset i.e., when there is a lower side push on the piston and the connecting rod by the rotating crankshaft. As per an embodiment of the present invention, the cut out may be provided on only one lateral side of the connecting rod in case where connecting rod is configured with an offset whereas a pair of symmetric cut-outs may be provided on lateral side of the connecting rod when the connecting rod is configured with no offset.
[00021] As per another aspect of present invention, the feature of one or more cut out is provided at the end portion of the cylinder liner/ cylinder sleeve, end portion being towards the crankshaft. The one or more cut out is configured to provide a clearance for the connecting rod when the connecting rod moves in a lateral direction when viewed from a direction along the axis of the crankshaft.
[00022] As per yet another aspect of present invention, the one or more cut out is perpendicular to the axis of a piston pin/ gudgeon pin when the engine is in assembled condition.
[00023] As per another aspect of present invention, one or more cut out being semi-circular in shape.
[00024] As per yet another aspect of present invention, the one or more cut out is having a radius of 0.1mm to 10mm.
[00025] As per another aspect of present invention, the one or more cut out comprises of curved edges to prevent the cylinder liner/ cylinder sleeve from stress being accumulated at the cylinder liner/ cylinder sleeve edges.
[00026] As per yet another aspect of present invention, the one or more cut out is created by removing excess material from the end portion of the cylinder sleeve to provide the clearance for the connecting rod when the connecting rod moves laterally in & out of the one or more cut out. This, also, helps in weight reduction of the IC engine. Further, no alignment related issues are prevalent since no new part is added in the IC engine. Furthermore, the internal combustion engines with the one or more cut out have improved fuel mileage.
[00027] The details provided above explains the basic features of the invention and does not limit the scope of the invention. The nature and further characteristic features of the present subject matter will be made clearer from the following descriptions made with reference to the accompanying drawings.
[00028] Exemplary embodiments detailing features of an internal combustion engine, in accordance with the present subject matter will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present subject matter will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the present subject matter. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
[00029] The present subject matter 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.
[00030] Fig.1 and Fig. 2 exemplarily illustrates a top perspective view of a cylinder block 100. Figure 1 and 2 shall be discussed together. The cylinder block 100 comprises of a cylinder barrel 101 and a cylinder sleeve 102. The cylinder barrel 101 being configured to enclose the cylinder sleeve 102. The cylinder sleeve 102 being configured to enclose a piston 107 (shown in fig.7). The cylinder barrel 101 is a metal casting containing a cylinder of an internal-combustion (IC) engine 200 (shown in fig.4). Further, one or more fins (or ribs) 105 are provided on the surfaces of cylinder barrel 101 and cylinder head (not shown). The one or more fins 105 increases the outer contact area of the cylinder barrel 101 for facilitating more surface area for the air to pass for cooling purposes. The one or more fins 105 are, generally, casted integrally with the cylinder barrel 101. Furthermore, the cylinder sleeve 102 is also provided in the IC engine 200. The cylinder sleeve 102 is thin metal cylinder-shaped part which is inserted into the IC engine 200 to form an inner wall of the cylinder block 100.
[00031] As per an embodiment of the present invention, the cylinder sleeve 102 includes a second cut out 103 for oil lubrication in the IC engine 200. Further, the cylinder sleeve 102 comprises of one or more first cut out 104. The one or more cut out 104 is provided at one peripheral edge at one end portion of the cylinder sleeve 102, the one end portion being towards the crankshaft axis. The one or more first cut out 104 is provided in such a way that the one or more first cut out is perpendicular to the axis of the gudgeon pin 108 (shown in Fig. 4) in assembled condition to provide better dynamic clearance between the cylinder sleeve 102 and the connecting rod 106.
[00032] Fig. 3 exemplarily illustrates a side perspective view of the cylinder block 100. In the cylinder block 100, there is a provision of one or more cut out 104 provided at the end portion of the cylinder sleeve 102. The one or more cut-out 104 feature improves the dynamic clearances and avoids any functional failure of the parts present in the IC engine 200. The one or more cut out 104, further, reduces the mechanical friction and side thrust of the piston 107 since the crankshaft offset is accommodated effectively. As per an aspect of the present invention, the one or more first cut out 104 is oriented along the lateral direction of movement of the connecting rod 106.
[00033] The cylinder sleeve 102 has one or more first cut-out 104. The dynamic clearance between the connecting rod 106 and the cylinder sleeve 102 is improved by one or more first cut-out 104. Further, the one or more first cut out 104 provides the dynamic clearance when there is higher crank offset i.e., when there is a lower side push on the piston 107 and the connecting rod 106 owing to the rotating crankshaft 110. The one or more first cut out 104 is configured to provide a clearance for the connecting rod 106 when the connecting rod 106 moves perpendicular to the one or more first cut out 104. Further, the one or more first cut out 104 is perpendicular to the axis of the gudgeon pin 108 when the IC engine 200 is in assembled condition. Further, in the present embodiment, the one or more first cut out 104 is semi-circular in shape and the one or more first cut out 104 is having a radius of 0.1mm to 10mm. However, the shape of the one or more first cut out 104 can be modified based on the shape of the connecting rod 106. As per an embodiment, the shape of the one or more first cut out 104 can be a one of an portion of an oval shape, a circular shape, or any other geometric shape. The one or more first cut out 104 comprises of curved edges to prevent the cylinder sleeve 102 from stress that is accumulated at the edges of cylinder sleeve 102. Furthermore, the one or more first cut out 104 is created by removing excess material from the end portion of the cylinder sleeve 102 to provide the clearance for the connecting rod 106 when the connecting rod 106 moves perpendicular to the one or more first cut out 104.
[00034] Fig.4 exemplarily illustrates an exploded perspective view of a partially shown IC engine 200. The IC engine 200 comprises of a crankcase 109. The crankcase 109 further comprises of a crankshaft 110 having a crankshaft axis AA’. The crankshaft 110 is a shaft driven by a crank mechanism consisting of a series of cranks and crankpins to which the connecting rod 106 of the IC engine 200 is attached. The crankshaft 110 is a mechanical part which is able to translate the reciprocating motion of the piston 107 into the rotational motion.
[00035] Further, in IC engines 200, the gudgeon pin 108 is provided to connect the piston 107 to the connecting rod 106 along axis CC’ and works as a bearing for the connecting rod 106 to pivot upon as the piston 107 moves.
[00036] Furthermore, the cylinder sleeve 102 which is a thin-walled hard metal cylinder is inserted into a cylinder block 100 of the IC engine 200. The cylinder sleeve 102 is made in the shape of the cylinder barrel 101 having a flange 111 at the top. The flange 111 keeps the cylinder sleeve 102 in position in the cylinder block 100. The cylinder sleeve 102 fits accurately in the cylinder barrel 101. The contact of the cylinder sleeve 102 with the cylinder block 100 should be such that sufficient and effective cooling of the cylinder sleeve 102 can be achieved. Also, the gas pressure, piston thrust, and impact loading during combustion are resisted by the combined thickness of the cylinder sleeve 102 and the cylinder barrel 101 of the IC engine 200.
[00037] Fig.5a and 5b exemplarily illustrates a graphical representation between a crank angle and the clearance provided by one or more first cut out 104 for the connecting rod 106 at various crank angles. As can be viewed from fig. 5a, there is less clearance (x) available between the cylinder sleeve 102 and the connecting rod 106, when the one or more first cut out 104 is not present. Further, in fig. 5b, the clearance between the cylinder sleeve 102 and the connecting rod 106 is increased from x to y. It can be observed in fig. 5b that the crank offset provided in IC engine 200 is adjusted or can be enhanced by providing the one or more first cut out 104 and the clearance on both diagonally opposite the sides of the connecting rod 106 is almost equal.
[00038] 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: Cylinder Block
101: Cylinder Barrel
102: Cylinder Sleeve/ Cylinder Liner
103: Second Cut out for oil lubrication
104: One or more first cut out
105: Fins
106: Connecting rod
107: Piston
108: Gudgeon Pin/ Piston Pin
109: Crankcase
110: Crankshaft
111: Flange
200: IC Engine
AA’: Crankshaft axis
BB’: Connecting rod crankshaft end axis
CC’: Gudgeon pin axis
,CLAIMS:We claim:

1. An internal combustion engine (200) comprising:
a cylinder head,
a crankshaft having an axis AA’
a cylinder block (100), said cylinder head being mounted on said cylinder block; and
a connecting rod (106);
said cylinder block (100) includes a cylinder barrel (101) and a cylinder sleeve (102); said cylinder barrel (101) being configured to enclose said cylinder sleeve (102); and said cylinder sleeve (102) being configured to enclose a piston (107),
said connecting rod (106) having a first end and a second end, said first end being configured to connect said piston (107) to a crankshaft (110), said second end being configured to connect to said piston (107) through a gudgeon pin (108),
wherein,
one or more first cut out (104) being provided at a peripheral edge of an end portion of said cylinder sleeve (102), said end portion being towards said axis AA’ of said crankshaft, said one or more first cut out (104) being configured to provide a working clearance for said connecting rod (106) when said connecting rod (106) operates laterally towards said one or more first cut out (104).

2. The internal combustion engine (200) as claimed in claim 1, wherein said one or more first cut out (104) being semi-circular in shape.

3. The internal combustion engine (200) as claimed in claim 1, wherein said one or more first cut out (104) being one of a portion of an oval shape, a arc shape, or any other geometric profile.

4. The internal combustion engine (200) as claimed in claim 2, wherein said one or more first cut out (104) having a radius in the range of 0.1mm to 10mm.

5. The internal combustion engine (200) as claimed in claim 1, wherein said one or more cut out (104) being perpendicular to an axis CC’ of said gudgeon pin (108), when said IC engine (200) being in assembled condition.

6. The internal combustion engine (200) as claimed in claim 1, wherein said one or more cut out (104) comprises of curved edges.
7. The internal combustion engine (200) as claimed in claim 1, wherein said one or more cut out (104) being created by removing excess material from said end portion of said cylinder sleeve (102) for providing said clearance for said connecting rod (106) when said connecting rod (106) moves laterally