Claims:I/We Claim:
1. An internal combustion engine (180) comprising:
at least one crankcase (201), said at least one crankcase (201) receiving a crankshaft (210);
at least one cylinder head (203); and
at least one cylinder block (202), said at least one cylinder block (202) includes a substantially rectangular receiving portion (304) and a cylinder bore (308) portion, said receiving portion (304) of said cylinder block (202) receives said cylinder head (203);
wherein,
said receiving portion (304) being configured with a plurality of pockets (309a, 309b, 309c, 309d);
wherein,
at least a first plane (M) and a second plane (N) being drawn tangential to outmost edges of at least one of said plurality of pockets (309a, 309b, 309c, 309d); said at least first plane (M) and said second plane (N) make an angle (?) with respect to a cylinder axis of said receiving portion (304).
2. The internal combustion engine (180) as claimed in claim 1, wherein said angle (?) being in a range of 30 degree angle to 40 degree.
3. The internal combustion engine (180) as claimed in claim 1, wherein each of said plurality of adjacent pockets (309a, 309b, 309c, 309d)being equidistance from each other.
4. The internal combustion engine (180) as claimed in claim 1, wherein said plurality of pockets (309a, 309b, 309c, 309d) formed on said receiving portion (304) to receive lubricating fluid.
5. The internal combustion engine (180) as claimed in claim 1, wherein said receiving portion (304) includes a plurality of cylinder head bolt slots (305a, 305b, 305c, 305c, 305d) configured to receive a plurality of cylinder head bolts (303a, 303b, 303c, 303d).
6. The internal combustion engine (180) as claimed in claim 1, wherein said plurality of cylinder head bolt slots (305a, 305b, 305c, 305c, 305d) being disposed on four corners of said receiving portion (304).
7. The internal combustion engine (180) as claimed in claim 1, wherein each of said plurality of pockets (309a, 309b, 309c, 309d) being disposed at a predetermined distance from each of adjoining cylinder head bolt slots (305a, 305b, 305c, 305c, 305d).
8. The internal combustion engine (180) as claimed in claim 1, wherein each of said plurality of pockets (309a, 309b, 309c, 309d) has a predetermined depth and are tapered in such a manner that the top width of each of said plurality of pockets (309a, 309b, 309c, 309d) on said receiving portion 304 is greater than the bottom width of each of said plurality of pockets (309a, 309b, 309c, 309d) at said predetermined depth.
9. The internal combustion engine (180) as claimed in claim 1, wherein each of said plurality of pockets (309a, 309b, 309c, 309d) an obtuse angle towards said plurality of cylinder head bolt slots (305a, 305b, 305c, 305c, 305d) to accommodate each of said plurality of cylinder head bolt slots (305a, 305b, 305c, 305c, 305d).
10. The internal combustion engine (180) as claimed in claim 1, wherein said receiving portion (304) and said cylinder head (203) includes a sealing member in between said receiving portion (304) and said cylinder head (203).
11. The internal combustion engine (180) as claimed in claim 10, wherein a plurality of pockets (309a, 309b, 309c, 309d) provide minimum surface contact of said sealing member with a receiving portion (304) of said internal combustion engine (180).
12. The internal combustion engine (180) as claimed in claim 1, wherein said plurality of pockets (309a, 309b, 309c, 309d) being created on said receiving portion (304) in between said plurality of cylinder head bolt slots (305a, 305b, 305c, 305c, 305d) and said cylinder bore (308 ).
13. The internal combustion engine (180) as claimed in claim 1, wherein said plurality of pockets (309a, 309b, 309c, 309d) having less material mass as compared to rest of said receiving portion (304), and being situated at an elevation lower than rest of said receiving portion (304).
14. The internal combustion engine (180) as claimed in claim 1, wherein each of wherein said plurality of pockets (309a, 309b, 309c, 309d) is of a geometric cross-sectional shape, wherein said geometric cross-sectional shape includes a trapezoidal profile with rounded corners.
15. The internal combustion engine (180) as claimed in claim 14, wherein said trapezoidal profile of each of said plurality of pockets (309a, 309b, 309c, 309d) has its bottom edge facing a cylinder bore (308).
16. The internal combustion engine (180) as claimed in claim 1, wherein an edge of said plurality of pockets (309a, 309b, 309c, 309d) face the cylinder head bore (308) in a curvilinear manner substantially parallel to the circular profile of said cylinder bore (308) forming a predetermined wall thickness (T1) on the inner side of each of said plurality of pockets (309a, 309b, 309c, 309d).
17. The internal combustion engine (180) as claimed in claim 1, wherein an upper edge of each of said plurality of pockets (309a, 309b, 309c, 309d) forms a substantially circular profile parallel to a plurality of cylinder bolt head slots (305a, 305b, 305c, 305d) forming a predetermined wall thickness T2 on the outer side of each of said plurality of pockets (309a, 309b, 309c, 309d).
18. The internal combustion engine (180) as claimed in claim 16, wherein said predetermined wall thickness (T1) on the inner side is substantially equal to a predetermined wall thickness (T2) on the outer side of each of said plurality of pockets (309a, 309b, 309c, 309d).
, Description:TECHNICAL FIELD
[0001] The present subject matter described herein generally relates to a vehicle, and particularly but not exclusively relates to an internal combustion engine of a vehicle.
BACKGROUND
[0002] Typically, an engine acts as a power source for a two-wheeler. The main components of the engine comprise of a cylinder head, an cylinder block, and a crank case. The internal components of the engine include a crankshaft, one or more connecting rods, a piston, a spark plug, a fuel injector, one or more intake and exhaust valves, one or more cam shaft, and a timing chain or cam chain.
[0003] Usually, in spark ignition engines a cylinder block along with a cylinder head is configured as a combustion chamber, to facilitate ignition of the fuel and air mixture. As the piston compresses the fuel and air mixture make contact with the spark generated by the spark plug present in the cylinder head; then the mixture is combusted and pushed out of the combustion chamber in the form of energy.
[0004] The cylinder block is configured to facilitate reciprocating movement of the piston. The piston is housed in the cylinder block, along with a cam chain or a timing chain and a cylinder liner. The piston is connected to the crankshaft on one end, through a connecting rod. The crankshaft is further housed within the crankcase assembly. The cam chain or timing chain is connected on one end to a cam shaft, housed within the cylinder head and on other end to the crankshaft, housed within the crank case.

BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The detailed description is described with reference to an embodiment of a saddle type two wheeled vehicle with an internal combustion engine along with the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0006] Fig. 1 illustrates a side view of a vehicle in accordance with an embodiment of the present invention.
[0007] Fig. 2 illustrates a side perspective view of the internal combustion engine, according to an embodiment of the present subject matter.
[0008] Fig. 3 illustrates a side perspective view of a portion of the internal combustion engine elaborating the internal parts of the internal combustion engine, according to an embodiment of the present subject matter.
[0009] Fig. 4 illustrates a side perspective view of the internal combustion engine without a crankcase, according to an embodiment of the present subject matter.
[00010] Fig. 5 illustrates an exploded perspective view of the internal combustion engine without a crankcase, according to an embodiment of the present subject matter.
[00011] Fig. 5a to Fig. 5c illustrates a top perspective view of a cylinder block of an internal combustion engine, according to an embodiment of the present subject matter.
[00012] Fig. 6a to Fig. 6b illustrates a cut section perspective view of a cylinder block of an internal combustion engine, according to an embodiment of the present subject matter.

DETAILED DESCRIPTION
[00013] Generally, two-wheeler engines are either two-stroke or four-stroke engines. The two stroke engines are usually used because of their cost efficiency and lighter built, in vehicles like go-karts. The two-stroke engines typically have one piston and a crankcase. In such engines, the crankcase is used for the gas exchange. The two-stroke engines also have a spark plug and an intake port as well as an exhaust port. A crucial difference between the two stroke and the four-stroke engine lies in the presence of a transfer port in the two-stroke engine.
[00014] The two-stroke engine completes a power cycle with two strokes (up and down movements) of the piston during only one crankshaft revolution. In the first stroke cycle, a first fuel air mixture is drawn via the intake port. Therefore, the fuel air mixture is added to the existing mixture in the crankcase. At the same time the mixture is compressed in the combustion chamber and ignited by the spark plug, which further initiates the second cycle. During the second cycle, the hot air expands and pushes the piston downwards increasing the volume of the combustion chamber resulting in the release of hot burned gases from the exhaust port of the ongoing cycle. Because of the downward motion of the piston, a fresh air fuel mixture which was sucked in during the compression of the previous cycle is now forced into the combustion chamber via a transfer port. At the same time the fresh air fuel mixture scavenges out the remains of the burned gases from the previous combustion cycle via an opened exhaust port.
[00015] In a four-stroke engine, the power is produced in the engine by a four-stroke process. Firstly, during the movement of the piston towards the bottom dead centre of the engine from a top dead centre, a vacuum is created in the combustion chamber. Due to the created vacuum, the air fuel mixture is sucked in via the intake valve (s), filling the combustion chamber with a fresh charge enriched with oxygen and hydrocarbons. Secondly, the intake valve closes and the piston moves upward towards the top dead centre results in gradual compression of the air fuel mixture. This compression stroke develops a pressure within and increases the in-cylinder temperature making the air fuel mixture ready for combustion.
[00016] While the compression stroke is in progress, and the piston is few crank degrees behind the top dead centre, an approximate of 25000 V of energy stepped up by the ignition coil, is transferred to the spark plug generating a spark across its electrodes, which further ignites the compressed charge. Further, the burned charge followed by a flame front travels all along the combustion volume and reaches the last unburned charge molecule, resulting in complete combustion by igniting the whole mixture. Furthermore, during the expansion stroke, due to the burning of the air fuel mixture, the pressure of the combustion chamber increases which results in the movement of the piston from the top dead centre to the bottom dead centre. Lastly, in the exhaust stroke, i.e., the fourth stroke, the piston moves from the bottom dead centre to the top dead centre, pushes the burned exhaust gases out of the combustion chamber via the exhaust valves.
[00017] During certain engine operating periods, combustion gases that enter the exhaust manifold are not completely burned. The combustion gases will continue to burn in the exhaust manifold if a sufficient amount of oxygen is available. Secondary air injection systems are used to inject additional air into the exhaust flow to allow combustion to continue, which improves the performance of exhaust after treatment systems and reduce emissions. A secondary air injection system contains a valve which is vacuum controlled. In some known arts a vacuum controlled SAI valve is replaced by an electrically controlled SAI valve for quick, precise and accurate response. The SAI valve location is shifted to the vehicle centre. It is placed exactly behind the cover cylinder head, above the crankcase and nearer to the air filter. It is mounted to a bracket which is mounted to another bracket that is welded to the rearward centre tube frame.
[00018] The cylinder block is configured to facilitate reciprocating movement of the piston. The piston is housed in the cylinder block along with a cam chain or a timing chain and a cylinder liner. The piston is connected to the crankshaft on one end, through a connecting rod. Usually, all these four strokes occur or are driven by the reciprocating movement of the piston along with opening and closing of one or more inlet and one or more exhaust valve.
[00019] Some known arts disclose that in order to facilitate the operations inside the cylinder block, the cylinder block is made as a thick block with thick material mass. The cylinder block further includes a cylinder liner and a piston. One or more piston rings (usually a metallic split ring) are attached to an outer diameter of the piston.
[00020] The cylinder liner, serves as the inner wall of the cylinder block and forms a sliding surface for the piston rings while retaining the lubricant within. The main functions of the cylinder liner along with the piston rings include: sealing the combustion chamber so that there is minimal loss of gases to the crank case; high anti-galling; improving heat transfer from the piston to the cylinder wall; maintaining adequate quantity of the lubricating fluid between the piston and the cylinder wall; and regulating lubricating fluid consumption by scraping oil from the cylinder walls back to a lubrication sump.
[00021] Maximum temperature is generated in the cylinder head usually during the combustion stroke. Since, all these strokes occur rapidly and continuously to drive the vehicle, the temperature of the cylinder head increases rapidly. Therefore, due to high operating temperatures inside the cylinder head of the engine assembly, appropriate cooling has to be taken care for adequate dissipation of heat.
[00022] One such known method of cooling includes providing cooling fins externally to the cylinder block and also on the cylinder head for adequate circulation of air on the surface of the cooling fins and for heat dissipation that is generated inside the cylinder head and cylinder block.
[00023] Some other known arts disclose that the cylinder liner that is situated inside the cylinder block is usually made of a thick mass of material, which is required to support operation of piston and the functionality of strokes in the cylinder block.
[00024] Further, the cylinder block includes a receiving portion that receives the cylinder head. Particularly, the receiving portion of the cylinder block is the top portion of the cylinder block where the cylinder head mates with the cylinder block through a plurality of cylinder head bolts. The mass of metal material in such receiving area of the cylinder block is usually thick to effectively take the load of the cylinder head bolts inserted during the engine assembly. Moreover, thick material mass is also configured more in the regions of the receiving portion of cylinder block that receives the cylinder head bolts; this is done to withstand the torque applied during drilling of the cylinder head bolts into the regions of the receiving portion of the cylinder block.
[00025] Therefore, because of the thick material mass intentionally accumulated in the regions of the cylinder block of the engine, particularly in regions of the receiving portion that receive the cylinder head bolts; inadequate cooling occurs. .
[00026] Furthermore, because of such inadequate cooling of the regions of the receiving portion that receive the cylinder head bolts, the heat is transferred to the cylinder liner in the cylinder block as well. This transfer of heat causes high thermal load.
[00027] Eventually, because of such high thermal load, the cylinder liner in the cylinder block along with the regions of the receiving portion that receive the cylinder head bolts undergoes distortion. Such distortion gradually changes the shape of the cylinder liner. Resultant to which, proper guidance to the piston provided by the cylinder liner fails.
[00028] Usually there is high friction present between the piston and the cylinder liner during the rapid reciprocating movement of the piston. Therefore, the distortion of the cylinder liner also results in higher friction between the piston and the cylinder liner, which results in higher consumption of lubricating fluid in order to reduce the excess friction.
[00029] Furthermore, the distortion of the receiving portion of the cylinder block that receives the cylinder head along with the liner distortion also leads to ineffective contact of a sealing member or gasket with the surface of the cylinder block. This ineffective contact of the sealing member or gasket eventually leads to leakage of the lubricating fluid which is usually pumped from the oil sump to the cylinder block. This leakage again results in excess consumption of lubricating fluid, than what is required during normal operation.
[00030] Furthermore, due to failure of adequate sealing by the oil sealing member or gasket, because of the distorted receiving portion of the cylinder block, the distorted liner and overall temperature rise owing to inadequate cooling; the lubricating fluid dissipates in gaseous form and escapes into the cylinder head, contaminating the combustion chamber. As a result, more unburned hydrocarbons are produced and emitted as exhaust gases. Eventually, the overall efficiency of the engine assembly is compromised.
[00031] Moreover, some known arts disclose that smaller surfaces are more effective for sealing purposes when compared with larger surface area, this is because, the stress on the sealing member is more with a smaller surface area. Therefore, for a sealing member or gasket to provide adequate sealing, it is desired to have a smaller surface area making contact with the sealing member or gasket.
[00032] Therefore, there is a need of an improved internal combustion engine design including a receiving portion with reduced material, such that at the same time enough material mass is maintained to bear torque or load applied during drilling of the cylinder head bolts into the cylinder block, while ensuring overall effective cooling along with effective sealing of the engine assembly.
[00033] Hence, there is a need of addressing the above circumstances and problems of the known arts.
[00034] The present subject matter has been devised in view of the above circumstances as well as solving other problems of the known art.
[00035] The present subject matter discloses an internal combustion engine which comprises of at least one crankcase, at least one cylinder head, and at least one cylinder block. The at least one crankcase receives a crankshaft. The at least one cylinder block includes a mating portion, a receiving portion and a cylinder bore. The receiving portion includes a plurality of cylinder head bolt slots configured to receive a plurality of cylinder head bolts. The receiving portion includes a plurality of pockets with removed material mass, and being situated at an elevation lower than rest of the receiving portion. When at least two planes are drawn tangential to outermost edges of at least one of the plurality of pockets, the at least two planes make an angle (?) with respect to a cylinder axis of the receiving portion.
[00036] As per an aspect of the present invention, the angle (?) is in a range of 30 degree angle to 40 degree.
[00037] As per an embodiment of the present subject matter, each of the plurality of pockets are equidistance from each adjacent pocket.
[00038] As per an aspect of the present subject matter, the plurality of pockets formed on the crankcase is configured to receive lubricating fluid.
[00039] As per another aspect of the present subject matter, the receiving portion of the cylinder block receives the cylinder head. As per another aspect, the plurality of cylinder head bolts aid in mating of the cylinder head and the receiving portion of the cylinder block.
[00040] As per an alternate embodiment, the plurality of cylinder head bolt slots is disposed on four corners of the receiving portion.
[00041] As per another aspect of the present subject matter, each of the plurality of pockets is disposed at a predetermined distance from each of adjoining cylinder head bolt slots
[00042] As per another aspect of the present subject matter, each of the plurality of pockets has a predetermined depth and tapered along the depth direction in such a manner that the top width of each of the plurality of pockets being greater than the bottom width of each of said plurality of pockets.
[00043] As per another aspect, the cylinder block includes a cylinder liner disposed inside said cylinder block. The plurality of pockets is created on the receiving portion in between the plurality of cylinder head bolt slots and the cylinder liner.
[00044] As per another aspect of the present subject matter, the receiving portion and the cylinder head include a sealing member, for example, a gasket, in between the receiving portion and the cylinder head.
[00045] Exemplary embodiments detailing features regarding the aforesaid and other advantages of the present subject matter will be described hereunder with reference to the accompanying drawings. Various aspects of different embodiments of the present invention will become discernible from the following description set out hereunder. Rather, the following description provides a convenient illustration for implementing exemplary embodiments of the invention. It should be noted that the description and figures merely illustrate principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof. Further, it is to be noted that terms “upper”, “down”, “right”, “left”, “front”, “forward”, “rearward”, “downward”, “upward”, “top”, “bottom”, “exterior”, “interior” and like terms are used herein based on the illustrated state or in a standing state of the two wheeled vehicles with a driver riding thereon. Furthermore, arrows wherever provided in the top right corner of figure(s) in the drawings depicts direction with respect to the vehicle, wherein an arrow F denotes front direction, an arrow R indicates rear direction, an arrow Up denotes upward direction, an arrow Dw denotes downward direction, an arrow RH denotes right side, and an arrow LH denotes left side. 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.
[00046] Fig. 1 illustrates a side view of a vehicle 100 in accordance with an embodiment of the present invention. The vehicle 100 includes a frame assembly (not shown) to support different parts of the vehicle 100. In an upper portion of the frame assembly (not shown), a handlebar assembly 115 is rotatably integrally connected to the steering shaft (not shown). The handlebar assembly 115 is used to steer the vehicle 100 and is connected to a front wheel 185 through the steering shaft (not shown) and a front fork assembly (195). An upper portion of the front wheel 185 is covered by a front fender 190 which prevents mud and water from getting deflected towards the steering shaft (not shown). Further, the front fork assembly (195) is supported on the front fender 190 by means of a brace fender (not shown).
[00047] In a front portion of the frame assembly (not labelled) a fuel tank assembly 120 is arranged immediately behind the handlebar assembly 115 and is disposed over a first power source, for example an internal combustion engine 180. A seat assembly 125 is placed behind the fuel tank assembly 120. The seat assembly 125 includes a front rider seating portion and a pillion rider seating portion. The pillion rider seating portion is placed on the rear part of the frame assembly (not shown), where the rear part of the frame assembly (not shown) is covered by the tail cover assembly (not labeled).
[00048] For the safety of the rider and in conformance with the traffic rules, a headlamp assembly 105 that includes a headlamp 110 and front indicator lights 140a are provided in the front portion of the vehicle 100. On the rear portion of the two wheeled vehicle 100 a tail lamp (not labeled) and rear indicator light 140b are provided on the rear portion of the tail cover assembly (not shown). Above the tail cover assembly 130 and behind the seat assembly 125 a pillion handle 135 is provided for the pillion rider to grab.
[00049] Suspension systems are provided for comfortable steering of the two wheeled vehicle 100 on the road. A front suspension assembly 195 serves as rigidity component for the front portion of the vehicle 100 just like the frame assembly (not shown). The front suspension assembly 195 is clamped to the head tube (not shown) through an upper bracket (not labeled) and a lower bracket (not labeled) is capable of being moved to the left and right. Further, a rear suspension system 160, which is a hydraulic damped arrangement, is connected to the frame assembly (not shown). The rear suspension system 160 comprises of at least one rear suspension 160 preferably disposed centrally in the longitudinal mid plane of the vehicle 100. However, in a vehicle 100 with two rear suspensions, the same may be disposed on the left side and the right side respectively of the vehicle 100.
[00050] The first power source, for example the internal combustion engine 180 is mounted to a front lower portion of the frame assembly (not shown) by means of an engine mounting bracket (not shown). The internal combustion engine 180 is partially covered on the lower side of the internal combustion engine 180 by an engine cover 175 also referred to as a crankcase cover. The internal combustion engine 180 is equipped with an exhaust system that includes an exhaust pipe connected to the internal combustion engine 180 and a muffler assembly 155 connected to the exhaust pipe. The muffler assembly 155 extends rearwards along the right side of the rear wheel 150.
[00051] Further, a swing arm 200 extending rearwards is swingably connected to a lower rear portion of the vehicle 100. The rear wheel 150 is rotatably supported at a rear end of the swing arm 200. Power from the internal combustion engine 180 is transmitted to the rear wheel 150 through a power drive mechanism, such as a drive chain, so as to drive and rotate the rear wheel 150. A center stand 165 is provided in between the front wheel 185 and the rear wheel 150 for parking the vehicle 100.
[00052] A rear fender 145 for covering an upper side of the rear wheel 150 is mounted to a rear portion of the vehicle 100 to prevent mud and water splashed by the rotating rear wheel 150 from entering the muffler assembly 155, the internal combustion engine 180 and other parts disposed close by. To enhance the overall aesthetics of the vehicle 100 and to prevent undesired foreign particles from entering parts of the vehicle 100, a plurality of rear covers (not labeled) is attached to a rear portion of the frame assembly (not shown).
[00053] Area below the seat assembly 125 and the fuel tank assembly 120 of the vehicle 100 is covered on both sides by a cover frame assembly 170. The cover frame assembly 170 includes the one or more side covers.
[00054] Fig. 2 illustrates a side perspective view of the internal combustion engine 180, according to an embodiment of the present subject matter. The internal combustion engine 180 includes a cylinder block 202 supported by a crankcase assembly 201 of the internal combustion engine 180. The cylinder block 202 defines a cylinder portion at which a piston can perform reciprocating motion. A cylinder head 203 is mounted to the cylinder block 202 and the cylinder head 203 acts as one end of the cylinder portion. The cylinder block 202 is provided with cooling fins 206 and the cylinder head 203 may be provided with the cooling fins 206.
[00055] Moreover, usually, in a scooter type vehicle having forced air cooling system which typically consists of cooling fan, cowl around cylinder block 202 and cylinder head 203, beadings. The cooling fan is driven by crankshaft 210 and the cowls guide the air onto cylinder block 203 and cylinder head 202. These cowls form a closed structure around the cylinder block 203 and cylinder head 202 and butts against the periphery of the cylinder block 203 at the bottom and cylinder head 202 at the top. Such cooling system typically consists of two cowls, a cowl L and cowl R when viewed from top. In forced cooling system, the air which cools the engine parts exits through the opening provided in the cowl L and cowl R under the cylinder head. A throttle cable guide is provided on the top part of the deflector. If improperly routed, the throttle cable will get damaged by rubbing with the frame parts during vehicle running condition, therefore this guide routes the throttle cable and avoids fouling with the metal parts such as frame and brackets. The breather system for crankcase 201 ventilation is provided in the cylinder head cover and is connected to air filter via a rubber hose. As this routing of rubber hose which connect air filter and cylinder head cover is in the vicinity of utility box and frame and may get damaged or squeezed while vehicle in operation which affects the breather performance, oil entry into air filter if the hose is left freely. To avoid such failure, a guide on the cowl L is provided to route the rubber hose in the required direction.
[00056] The internal combustion engine 180 comprises a piston (not shown) performing a reciprocating motion in the cylinder portion due to force imparted to it by the combustion of air-fuel mixture. This reciprocating motion is converted and transferred to a rotary motion of a crankshaft 210 through a connecting rod (not shown). Further, a cylinder head-cover 204 is mounted to the cylinder head 203. The crankcase assembly 201 is made up of left-side crankcase cover and right-side crankcase cover and a middle crankcase member. The crankcase assembly 201 rotatably supports the crankshaft 210. Further, an electric machine like a magneto assembly 211 or an integrated starter generator is mounted to the crankshaft 210. The magneto assembly 211 during operation is used to charge a battery (not shown).
[00057] The cylinder head 203 includes an intake port 205 and an exhaust port 208 (shown in Fig. 3) that are provided on a first face and a second face of the cylinder head 203. In the present embodiment, the first face is an upward facing side and the second face is a downward facing side thereof. Further, the cylinder head 203 supports a camshaft assembly (not shown) that is capable of operating intake valve(s) and exhaust valve(s) of the internal combustion engine.
[00058] Fig. 3 illustrates a side perspective view of a portion of the internal combustion engine 180 elaborating the internal parts of the internal combustion engine 180, according to an embodiment of the present subject matter.
[00059] The internal combustion engine 180 includes a gear oil pump drive (not labelled) connected to the crankshaft 210 and rotates integrally with it. The gear oil pump drive includes a primary driving gear 213. The primary driving gear 213 acts a primary drive and is capable of transferring rotational force or torque to a primary driven gear (not shown). The primary driven gear is thus operably connected to the crankshaft 210. The cylinder head 203 comprises a valve train arrangement to control opening and closing of intake and exhaust valves present at the intake port 205 (shown in Fig. 2) and one or more exhaust ports 208 thereby controlling intake of air-fuel mixture and outlet of exhaust gases. The camshaft assembly (not shown) is rotatably mounted to the cylinder head 203 (shown in Fig. 2). A cam chain (not shown) operably connects the crankshaft 210 and camshaft assembly. A driven sprocket of the camshaft assembly is configured to be meshed with the primary driving gear 213 and the driven sprocket transfers the rotary motion of the crankshaft 210 to the camshaft assembly.
[00060] Typically, the transmission assembly of the internal combustion engine 180 includes a spring-loaded multiplate friction clutch assembly 207 fixedly attached to the left-hand portion of the crankshaft 210 using plurality of fastening means. The right-hand side of the crankcase 210 encloses a dry magneto assembly 211. The dry magneto assembly 211 is configured to rotate along with the crankshaft 210 to generate power which recharges the battery (not shown) and as per an alternate embodiment can be an Integrated Starter Generator (ISG) machine. Further, as per an embodiment, a centrifugal fan (not shown) is disposed in front of the magneto assembly 211 forming part of a cooling system of the internal combustion engine 180 to cool the internal combustion engine 180. The centrifugal fan (not shown) rotates along with the crankshaft 210 and draws atmospheric air inside and circulates it throughout the interior portions of the shroud (not shown).
[00061] The clutch assembly 207 further includes one or more clutch plates 207a, a clutch hub 207b, and a flywheel (not shown). The clutch assembly 207 is fixedly attached by fastening means to an input shaft (not shown). The clutch assembly 207 ensures that the power transmission from the internal combustion engine 180 is engaged and disengaged to the rear wheel 150 (as shown in Fig. 1) based on rotational speed of the engine.
[00062] During running of the vehicle 100 a large amount of heat is generated inside the internal combustion engine 180. For reducing the impact of the heat on the piston, the cylinder block 202 (shown in Fig. 2) and other engine parts, an oil sump 212 is provided in the crankcase 201 to store oil and collect the falling oil during normal operation to be cycled again through an oil drain plug 214.
[00063] Usually, the oil sump 212 is provided at the bottom-side of the left-hand side of the crankcase 201 for continuous lubrication and cooling of a piston and a plurality of piston cylinder wall and other parts of the internal combustion engine 180.
[00064] Fig. 4 illustrates a side perspective view of a portion of the internal combustion engine 180 without a crankcase 201, according to an embodiment of the present subject matter. The present illustration illustrates a cylinder block 202, a cylinder head 203 and a cylinder head cover 204. The cylinder block 202 and the cylinder head 203 are mated along a plane XX’ (shown by dotted line).
[00065] Usually, in spark ignition engines 180, the cylinder block 202 along with the cylinder head 203 is configured as a combustion chamber (not shown), to facilitate ignition of the fuel and air mixture. The cylinder block 202 is configured to facilitate reciprocating movement of the piston (not shown). The piston is housed inside the cylinder bore 302 (shown in Fig. 5) of the cylinder block 202 along with a cam chain or a timing chain and a cylinder liner (not shown). The piston is connected to the crankshaft 210 (shown in Fig. 2) on one end, through a connecting rod (not shown).
[00066] Usually, all strokes occur or are driven by the reciprocating movement of the piston along with opening and closing of one or more inlet and one or more exhaust valve (not shown). As the piston compresses the fuel and air mixture and makes contact with the spark generated by a spark plug 301 present on the cylinder head 203; the mixture is combusted and exhaust gases are pushed out of the combustion chamber .
[00067] Fig. 5 illustrates an exploded perspective view of the internal combustion engine 180 without a crankcase 201, according to an embodiment of the present subject matter. The cylinder head 203 along with the cylinder head cover 204 is mated with the cylinder block 202 along and held in position by means of a plurality of cylinder head bolts (303a, 303b, 303c, 303d).
[00068] Maximum temperature is generated in the cylinder head 203 and the cylinder block 202 usually during the combustion stroke. Since, all these strokes occur rapidly and continuously to drive the vehicle, the temperature of the cylinder head 203 and the cylinder block 202 increases rapidly. Therefore, due to high operating temperatures inside the cylinder head 203 and the cylinder block 202, appropriate cooling has to be taken care for adequate dissipation of heat. Therefore, the cylinder block 202 along with the cylinder head 203 is externally covered by a plurality of cooling fins 206. The cooling fins 206 on the cylinder block 202 enable adequate circulation of air on the surface of the cooling fins206 and for heat dissipation that is generated inside the cylinder head 203 and cylinder block 202.
[00069] In order to facilitate the operations inside the cylinder block 202, the cylinder block 202 is made as a thick block with thick material mass. The cylinder block 202 further includes a cylinder liner 302 and the piston. One or more piston rings (usually a metallic split ring) (not shown) are attached to an outer diameter of the piston.
[00070] The cylinder liner serves as the inner wall of the cylinder bore 302 of the cylinder block 206 and forms a sliding surface for the piston rings while retaining the lubricant fluid within. The main functions of the cylinder liner along with the piston rings include: sealing the combustion chamber so that there is minimal loss of gases to the crank case 201; high anti-galling; improving heat transfer from the piston to the cylinder wall; maintaining the proper quantity of the lubricating fluid between the piston and the cylinder block 202 wall; and regulating lubricating fluid consumption by scraping oil from the cylinder block 202 walls back to an oil sump 212 (shown in Fig. 3).
[00071] The cylinder liner that lines the cylinder bore 302 from inside of the cylinder block 202 is usually made of a thick mass of material, which is required to support operation of piston and the functionality of strokes in the cylinder block 202.
[00072] Fig. 5a to Fig. 5c illustrates a top perspective and top view of a cylinder block 202 of an internal combustion engine 180, according to an embodiment of the present subject matter. The top view of the cylinder block 202 includes a substantially rectangular receiving portion 304 and a mating portion 202a. The receiving portion 304 of the cylinder block 202 receives the cylinder head 203. Particularly, the receiving portion 304 of the cylinder block 202 is the top portion of the cylinder block 202 where the cylinder head 203 mates with the cylinder block 202 along a plane XX’ (shown in Fig. 4) through a plurality of cylinder head bolts (303a, 303b, 303c, 303d) (shown in Fig. 5).
[00073] The receiving portion 304 includes a plurality of cylinder head bolt slots (305a, 305b, 305c, 305d ) to receive the cylinder head bolts (303a, 303b, 303c, 303d), a piston bore 308 to receive the piston along with the cylinder liner 302 (shown in Fig. 5), a cam chain slot 306 to receive a cam chain.
[00074] The wall thickness of the material of the receiving portion 304 of the cylinder block 202 is usually thick when compared with other parts of the engine 180, to effectively take the load of the cylinder head bolts (303a, 303b, 303c, 303d) inserted during the engine assembly. Moreover, the thick material mass is also configured more near the regions of the receiving portion 304 of cylinder block 202 that surrounds the regions receiving the cylinder head bolts (303a, 303b, 303c, 303d), herein called as plurality of cylinder head bolt slots (305a, 305b, 305c, 305d ). This is done to withstand the torque applied during drilling of the cylinder head bolts (303a, 303b, 303c, 303d) into the regions of the receiving portion 304 of the cylinder block 202.
[00075] Usually, because of such thick material mass of the cylinder block 202 of the engine 180, particularly near the regions of the receiving portion 304 of cylinder block 202 that surrounds the plurality of cylinder head bolt slots (305a, 305b, 305c, 305d ); inadequate cooling occurs in this region. Furthermore, because of such inadequate cooling of the regions of the receiving portion 304 regions of the receiving portion 304 of cylinder block 202, that surrounds the plurality of cylinder head bolt slots (305a, 305b, 305c, 305c), the heat is transferred to the cylinder liner disposed in the cylinder bore 302 of the cylinder block 202. This transfer of heat causes high thermal load. Eventually, because of such high thermal load, the cylinder liner in the cylinder block 202 along with the regions of the receiving portion 304 that receive the cylinder head bolts (303a, 303b, 303c, 303d) undergoes distortion. Such distortion gradually changes the shape of the cylinder bore 308 along with the cylinder liner 302. Resultant to which, proper guidance to the piston provided by the cylinder liner fails.
[00076] In the present subject matter, to combat such problem of inadequate cooling and high thermal load and ultimately to avoid distortion of cylinder bore 308 and receiving portion 304 distortion, a plurality of pockets (309a, 309b, 309c, and 309d) are created on the receiving portion 304 by removing material mass up to a predetermined depth B (shown in Fig. 6b ). The plurality of pockets (309a, 309b, 309c, and 309d) are created on the receiving portion 304 in between the plurality of cylinder head bolt slots (305a, 305b, 305c, 305c, 305d) and the cylinder liner 302. The plurality of pockets ensures that material mass of the cylinder block 202 especially on the receiving portion 304 is reduced, thereby enabling higher dissipation of heat across the material and thereby ultimately providing adequate cooling of the internal combustion engine 180. The adequate cooling of the internal combustion engine 180 further ensures that the distortion of the cylinder liner is prevented, thereby ensuring proper guidance to the piston, higher durability and life of the engine as a whole.
[00077] Figure 5c shows that if the centre of the cylinder block 202 is considered as a reference central point and planes are drawn radially outwardly from the centre of the cylinder block 202, such that at least two planes, for example, a first plane M and a second plane N, are tangential from outmost edges of at least one of the plurality of pockets (309a, 309b, 309c, 309d). Then the at least two planes (M, N), make an angle (?) with respect to the cylinder axis of the receiving portion 304. The angle ? approximately lies in the range of 30 to 40 degree angle.
[00078] As per an additional embodiment, the plurality of pockets (309a, 309b, 309c, 309d) formed on the receiving portion 304 also act as lubricant storage and supply units to provide lubrication quickly to the piston liner during engine operation therefore also ensures proper lubrication of the receiving portion 304 along with the cylinder head bolt slots (305a, 305b, 305c, 305c, 305d) and the cylinder bore 302. Such lubrication aids in minimizing the friction between the high friction present between the piston and the cylinder liner during the rapid reciprocating movement of the piston. Such minimizing of friction further aids in overall reduction of the consumption of the lubricating fluid.
[00079] Each of the adjacent pockets (309a, 309b, 309c, 309d) are equidistance (by a predetermined distance Y) from each of the plurality of pockets (309a, 309b, 309c, 309d). Along with it each of the plurality of pockets (309a, 309b, 309c, 309d) is disposed at a predetermined distance from each of adjoining cylinder head bolt slots (305a, 305b, 305c, 305c, 305d).
[00080] This equidistance arrangement between two pockets, along with the predetermined distance between each pocket and cylinder head bolt slots, ensures optimal removal of material mass from required regions of the receiving portion 304; While ensuring that the material mass around the cylinder head bolt slots (305a, 305b, 305c, 305c, 305d) required for withstanding the torque applied during drilling of the cylinder head bolts into the regions of the receiving portion 304 of the cylinder block 202 is maintained. Thereby, the required strength of the overall cylinder block 202 is maintained and not hampered.
[00081] Fig. 6a to Fig. 6b illustrates a cut section perspective view of a cylinder block 202 of an internal combustion engine 180, according to an embodiment of the present subject matter. The cut section shows, that while creating the desired plurality of pockets (309a, 309b, 309c, 309d), it is ensured each of said plurality of pockets (309a, 309b, 309c, 309d) is disposed at a predetermined distance from each of adjoining cylinder head bolt slots (305a, 305b, 305c, 305c, 305d). For example, distance “A”.
[00082] Moreover, each of the plurality of pockets (309a, 309b, 309c, 309d) has a predetermined depth, for example, ‘B’, and each of the plurality of pockets (309a, 309b, 309c, 309d) are tapered in such a manner that the top opening width of each of the plurality of pockets (309a, 309b, 309c, 309d) on the receiving portion 304 is greater than the bottom width of each of the plurality of pockets (309a, 309b, 309c, 309d) at the predetermined depth, for example, B. As per another aspect, each of the plurality of pockets (309a, 309b, 309c, 309d) forms an acute angle towards said plurality of cylinder head bolt slots (305a, 305b, 305c, 305c, 305d) to accommodate each of the plurality of cylinder head bolt slots (305a, 305b, 305c, 305c, 305d).
[00083] This is done to ensure that while the material mass required for adequate cooling is removed, at the same time the receiving portion 304 should have enough material mass around the plurality of cylinder head bolt slots (305a, 305b, 305c, 305d,) to be able to maintain enough mass to bear the torque or load applied during drilling of the cylinder head bolts (303a, 303b, 303c, 303d) into the cylinder block 202.
[00084] The plurality of pockets (309a, 309b, 309c, 309d) includes less mass as compared to the other zone/area of the cylinder block 202. As per an embodiment, each pocket is of a geometric cross-sectional shape e.g., a trapezoidal profile with rounded corners. As per an aspect the trapezoidal shape has its bottom edge facing the cylinder bore 308. As per another aspect, the edge facing the cylinder head bore 308 may be formed in a curvilinear manner substantially parallel to the circular profile of the cylinder bore 308 forming a pre-determined wall thickness T1 on the inner side. The upper edge may be formed with a substantially circular profile parallel to the cylinder bolt head openings (305a, 305b, 305c, 305d) forming a pre-determined wall thickness T2 on the outer side. As per an embodiment, the pre-determined wall thickness T1 on the inner side is substantially equal to the pre-determined wall thickness T2 on the outer side.
[00085] As per an efficiency of the present invention, the plurality of pockets provides minimum contact of the sealing member, for example, a gasket, with the receiving portion 304 of the internal combustion engine. This is because, the plurality of pockets (309a, 309b, 309c, 309d) are surfaces of the receiving portion 304 that are situated at lower elevation as compared to the other parts of the receiving portion 304. Such lower surface ensures that minimum contact is maintained between the sealing member and the other surface of the cylinder block. This minimum contact ensures better effective sealing of the sealing member with the receiving portion 304 and the cylinder head 203, because of the lesser stress provided in the reduced surface area.
[00086] Moreover, effective contact of the sealing member or the gasket aids in effectively minimizing leakage of lubricating fluid which is usually pumped from the oil sump 212 to the cylinder block 202. This minimization of leakage again results in reduced consumption of lubricating fluid, than what is required during normal operation. Furthermore, because of effective cooling of the engine 180, the dissipation of lubricating fluid in gaseous form into the cylinder head is prevented. Resultant to which, the contaminants inside the combustion chamber is drastically reduced, which further results in increasing the overall efficiency of the engine 180.
[00087] Hence the present subject matter achieves an improved design of an internal combustion engine 180 including a receiving portion 304 with reduced material, such that at the same time enough material mass is maintained to bear torque or load applied during drilling of the cylinder head bolts into the cylinder block, while ensuring overall effective cooling along with effective sealing of the engine assembly.
[00088] 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 NUMERAL
100 – Vehicle
105- Head lamp assembly
110- Head lamp
115- Handle bar assembly
120- Fuel tank assembly
125- Seat assembly
130- Tail cover assembly
135- Pillion handle
140a- Front indicator light
140b- Rear Indicator light
145- Rear fender
150- Rear wheel
155- Muffler assembly
160- Rear suspension system
165- Center stand
170- Cover frame assembly
175- Engine cover
180- Internal combustion engine
185- Front wheel
190- Front fender
195- Front suspension assembly
200- Swing arm
201- Crank case
202- Cylinder block
202a- mating portion
202b- Side face cylinder block
203- Cylinder head
204- Cylinder head cover
205- Intake port
206- Cooling fins
207- Clutch assembly
207a- Clutch plates
207b- Clutch hub
208- Exhaust port
210- Crankshaft
211- Magneto assembly
212- Oil sump
213- Primary driving gear
214- Oil drain plug
301- Spark plug
302- Cylinder bore
303 a,b,c,d- Cylinder head bolts
304- Receiving portion
305a,b,c,d- Cylinder head bolt slots
306- Cam chain slot
307- EGR port- Exhaust gas recirculation or SAI port(Secondary air injector)
308- piston slot
309a,b,c,d- pockets
T1, T2- Wall thickness