AN INTERNAL COMBUSTION ENGINE
FIELD OF THE INVENTION
[0001] The present invention relates generally to an internal combustion
engine and more particularly, but not exclusively, to the internal combustion engine for an automotive vehicle.
BACKGROUND OF THE INVENTION
[0002] A conventional two wheeled vehicle is powered by an internal
combustion^engine (hereinafter "engine") generally disposed at a lower half of the vehicle. This engine converts chemical energy into mechanical energy by combustion of air-fuel mixture within a combustion chamber of the engine. The engine, among other components, has a cylinder block comprising a cylinder head on the cylinder block and receiving a reciprocating piston from the bottom. 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 the cylinder block.
[0003] Such internal combustion (IC) engine during its operation
generates large amount of heat. Specifically, the combustion chamber and the area adjoining the combustion chamber is significantly heated due to the combustion process taking place within the combustion chamber. Such high temperature build up may lead to failure of valve seat as well as the valve seal of the valve train. If

the heat is not dissipated sufficiently, it may also leaves pit marks on the cylinder head and on the piston surface. Additional components near the combustion chamber, for example, an ignition device are affected. The high temperature may also lead to wear and tear of the insulation of ignition device. Additionally, the combustion chamber generates significant combustion noise which travels to cylinder head and can be bothersome for a vehicle rider.
[0004] In the past, forced liquid cooling systems have been used to
* effectively dissipate such large amount of heat. However, forced liquid cooled engines are complex, bulky and costly due to presence of radiator and other supporting elements. Specially in a two wheeled vehicle, such engines are also subject to packaging, layout and space constraints. Therefore, a need exists to present a simple, low cost alternative to cool a portion of the cylinder head above the combustion chamber and surrounding components in a four cycle internal combustion engine and dampen the combustion noise emanating from the cylinder head.
SUMMARY OF THE INVENTION
[0005] The present invention is directed to address all or any of the above
problems and to obviate a lacunae in the prior art. It is an object of the present subject matter to propose a multi-valve internal combustion engine having an oil jacket to cool the cylinder head where high temperature builds up when the engine is in operation. It is another object of the present invention to reduce the combustion noise emanating from the engine during the engine operation.

[0006] To this end, the present invention proposes an internal combustion
engine having a crankcase comprising an oil sump; a cylinder block having a cylinder bore; a cylinder head including at least two intake ports, at least one exhaust port and at least one threaded hole for accomodating an igniton device; a combustion chamber formed in a space between the cylinder head and cylinder block above the cylinder bore; at least one stud hole passing through cylinder block and allowing passage of oil from oil sump to cylinder head wherein the oil from the at least one stud hole enters the cylinder head through at least one oil supply duct which terminates at an oil jacket disposed substantially above the combustion chamber. The oil supply duct is disposed adjacent to the at least one exhaust port and a portion of the oil supply duct terminating at the oil jacket is disposed between the at least one exhaust port and the threaded hole.
[0007] The oil jacket in the multi-valve IC engine surrounds the at least
one ignition device and the at least one exhaust port substantially while also partially surrounding the at least two intake ports in the cylinder head. The oil jacket receives the oil, enroute to the valve train, from the oil sump. The entry of the oil into the oil jacket through the at least one oil supply duct located close to the at least one exhaust port is benefitial as the temperature is highest around the exhaust port. Soon afer entry, the oil first cools the combustion chamber and thereafter cools the ignition device. The circulation of oil in the portion of the cylinder head above the combustion chamber forms a layer which weakens the transmission of combustion noise to the upper portion of the cylinder head. Thus, the oil besides cooling the combustion chamber also dampens the combustion

noise emanating from the combustion chamber. The working temperature of the combustion chamber is maintained at an optimal level through the combination of natural air cooling and oil jacket. Thus, the present invention cools the engine in a simple and cost effective manner without the use of any externally mounted complex and bulky forced liquid cooling systems. The absence of forced liquid cooling system also enables optimal and easy mounting of the engine on the vehicle in the space available.
[0008] The foregoing objectives and summary is provided to introduce a .
selection of concepts in a simplified form, and is not limiting. To fully appreciate these and other objects of the present subject matter as well as the subject matter itself, all of which will become apparent to those skilled in the art, the ensuing detailed description of the subject matter and the claims should be read in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0009] The above and other, features, aspects, and advantages of the
subject matter will be better understood with regard to the following description and accompanying drawings where:
[00010] FIG. 1 shows a sectional view of a general construction of a four
cycle internal combustion engine.
[00011] FIG. 2 shows a side view of an upper portion of the IC engine
according to an embodiment of the present invention.

[00012] FIG. 3 shows a bottom view of the cylinder head taken along the
line X-X' according to the embodiment depicted in FIG. 2.
[00013] FIG. 4 shows a vertical sectional view of the upper portion of the
IC engine according to the embodiment depicted in FIG. 2.
[00014] FIG. 5 shows an illustrative and perspective view of an oil jacket
provided within the IC engine depicted in FIG. 2.
[00015] FIG. 6 shows a perspective view of the oil jacket within the IC
engine depicted in FIG. 2.
[00016] FIG. 7 shows a top view of a sealing member provided within the
IC engine depicted in FIG. 2.
[00017] FIG. 8 shows a top view of a cylinder block of the IC engine
depicted in FIG. 2.
DETAILED DESCRIPTION OF THE INVENTION
[00018] In order that those skilled in the art can understand the present
invention, the invention is further described below in detail so that various features of the invention thereof proposed here are discernible from the description thereof set out hereunder. However these descriptions and the appended drawings are only used for those skilled in the art to understand the objects, features, and characteristics of the present invention and not to be used to confine the scope and spirit of the present invention. First of all, the engine described here is a four cycle internal combustion engine. The engine is a multi-. Valve engine. In a preferred embodiment, said engine is mounted on a two

wheeled vehicle. However, the concepts described herein can also be used in the engine mounted on a three wheeled or a four wheeled vehicle.
[00019] FIG. 1 shows a side view of a general multi-valve four cycle
internal combustion (IC) engine. The engine 1 includes a crankcase 4, a cylinder block 3 coupled to the crankcase 4 and a cylinder head 2 coupled to an upper portion of the cylinder block 3. The cylinder head 2 is located above the cylinder block 3. and the crankcase 4 is located below the cylinder block 3, with the cylinder block 3 located between the cylinder head 2 and the crankcase 4. The cylinder block 3 has a centrally formed cylinder bore 20 allowing a reciprocating piston 5 to move slidably inside the cylinder bore 20. The piston 5 is connected to a crankshaft 8 through a connecting rod 7. The crankshaft 8 is rotatably supported by the crankcase 4. Further, FIG. 1 shows a vertical type engine where the cylinder block 3 is vertically oriented and disposed in such a way that the long axis of the cylinder block 3 is approximately perpendicular to the longitudinal axis of the crankshaft 8. However, the concepts disclosed herein are equally applicable on a horizontal engine where the cylinder block is forwardly tilted.
[00020] The cylinder head 2 comprises of at least two ports, at least one
exhaust port namely a first port 10 and at least one intake port namely a second port 9 which communicate with a combustion chamber 6 formed by being surrounded by the cylinder bore 20, the cylinder head 2 and the piston 5. The second port 9 allows the air-fuel mixture to enter the combustion chamber 6. After the mixture is combusted, the exhaust gases are taken out of the combustion chamber 6 through the first port 10. The first port is further connected to an

exhaust pipe 21 as shown in FIG. 2. To facilitate the entry of air-fuel mixture into the combustion chamber through the second port and the exit of exhaust gases from the-combustion chamber through the first port, a valve train having a plurality of valves is provided in the cylinder head 2. A first valve 11 is provided at the combustion chamber side opening of the first port 10 whereas a second valve 12 are provided at the combustion chamber side opening of the second port 9. The valves 11, 12 in the valve train are driven by a camshaft 14 rotatably supported in the cylinder head 2 so as to open and close them. Rotational power is transmitted from the crankshaft 8 to the camshaft 14 by a timing transmission means (not shown). In. an embodiment, the timing transmission means includes a drive sprocket supported on the crankshaft 8, a driven sprocket supported on the camshaft 14 and an endless cam chain connecting the drive sprocket with the driven sprocket.
[00021] FIG. 2 shows a multi-valve IC engine according to an embodiment
of the present invention wherein the cylinder head accommodates at least three valves to increase the-power of the engine and consequently at least three ports for better combustion of the air-fuel mixture. FIG. 3 shows a bottom sectional view of the cylinder head of the IC engine along the line X-X' depicted in FIG. 2. An additional intake port namely a third port 13 is provided in the cylinder head 2 which communicates with the combustion chamber 6 through a third valve (not shown). According to a preferred embodiment, out of the three ports, the cylinder head 2 has at least two intake ports and at least one exhaust port. Hence, the second port 9 and third port 13 support in the inlet of air-fuel mixture into the

combustion chamber 6 whereas the first port 10 supports in the outlet of exhaust gases after the combustion process is over. The second port 9 and the third port 13 function jointly and both of them are jointly operational at any point of time for the inlet function. Thus, the second port 9 and third port 13 act as intake ports whereas the first port 10 acts as exhaust port.
[00022] Further, besides the at least two intake ports 9, 13 and the at least
one exhaust port 10, the cylinder head also comprises at least one threaded hole 17 for accomodating an ignition device 15. As shown in FIG. 3, the threaded hole 17 is located adjacent to the first port 10 and approximately diagonally opposite to the third port 13. The ignition device 15 provides spark to ignite the compressed air fuel mixture which enters the combustion chamber through the second port 9 and third port 13. The ignition device 15 is connected to an electric power source, for example, a battery. When assembled, a portion of the ignition device 15, preferably the upper portion, remains above the combustion chamber 6. Another portion, preferably the lower portion*, peeps within the combustion chamber 6 to provide spark thus exposing it to high temperature during engine operation. A plane Y-Y' longitudinally divides the cylinder bore 20 into two halves. In a preferred embodiment, the threaded hole 17 and the first port 10 are disposed on one side of the plane Y-Y' whereas the second port 9 and third port 13 are disposed on the other side of said plane Y-Y'.
[00023] During the operation of the engine 1, significant heat is generated
within the combustion chamber 6. The components proximate to the combustion chamber 6 are also exposed to high temperatures for e.g. ignition device 15 and

the valves. The heat should be dissipated for efficient functioning of the engine 1. Therefore, the atmospheric air blowing towards the engine 1 is used to cool the cylinder head 2. As shown in FIG. 2, a plurality of fins (referred by the numeral 16) are provided on the outer surface of the upper portion of the engine 1 including that of cylinder head 2 and cylinder block 3.
[00024] The air however cools only the outer surface of the engine 1.
Therefore, the engine 1 is provided with a cooling system for carrying away the heat generated to the outer surface of the engine which then gets cooled through the environmental air. The crankcase 4 comprises of an oil sump 70 at a lower portion of the engine 1 storing a predetermined volume of oil for circulation within the engine [FIG. 1]. The oil circulates around various engine components including the ignition device 15 through dedicated openings spanning across the engine to significantly carry away the heat generated during engine operation. The oil also lubricates the various components of the engine including those in the crankcase and the cylinder head to reduce their wear and tear.
[00025] The IC engine comprises of an oil jacket 40 disposed substantially
above the combustion chamber 6 to cool the portion of the cylinder head above the combustion chamber. The oil in the oil jacket 40 cools the combustion chamber 6 and also dampens the noise emanated by said combustion chamber. The oil jacket 40 is now explained with the help of FIG. 2-5. The oil jacket 40 is disposed in the portion of the cylinder head 2 above the combustion chamber 6 and is formed in the space accomodating the first valve 11, second valve 12, the third valve and the ignition device 15. It is disposed substantially on one side of

the plane Y-Y' that longitudinally divides the cylinder bore 20 into two halves and having the ignition device 15 and the first port 10. A small portion of the oil jacket 40 also extends to the other side, of the plane Y-Y' having the second port 9 and the third port 13. As shown in FIG. 5, the oil jacket 40 substantially surrounds the threaded hole 17 receiving the ignition device 15 and the first port 10 receiving the first valve 11 so that the passage of the oil through the oil jacket 40 absorbs the heat present around the ignition device 15 and the first port 10.
[00026] The oil in the oil jacket 40 is pumped through the oil sump 70. As
shown in FIG. 3 and 4, the oil from the oil sump 70 is pumped against gravity towards the cylinder head 2 through at least one stud hole 30. The stud hole 30 passes through the cylinder block 3 towards a top portion of the cylinder head 2 and has a hollow cylindrical cross section. At least one stud 31 passes through the at least one stud hole 30 to secure the cylinder head 2 to cylinder block 3. In a preferred embodiment, the engine is provided with multiple such stud holes. The diameter of the stud hole 30 is bigger than the stud 31 and hence an annular opening is left between the stud hole 30 and the stud 31 through which the oil is pumped to the cylinder head 2. In this way, the stud hole 30 allows the passage of oil from the oil sump 70 to the cylinder head 2.
[00027] The oil from the stud hole 30 enters the cylinder head 2 through at
least one oil supply duct 32 disposed adjacent to the first port 10. The oil supply duct 32 is drilled into the cylinder head 2 and is operatively connected with the stud hole 30. The oil supply duct 32 terminates at the oil jacket 40. The oil is further carried upward for lubricating the valve train through a second oil. supply

duct 34 (FIG. 2). Thus, the oil from the oil sump 70 first exits from the stud hole 30 through the oil supply duct 32 and. then through the second oil supply duct 34. In an implementation, the ignition device 15 and the oil supply duct 32 are disposed substantially inclined to a central axis of the cylinder bore 20. This helps in assembly of these components considering the space constraints associated with the engine. .
[00028] According to a feature of the present invention, the oil supply duct
32 is routed from the stud hole 30 to the oil jacket 40 from between the threaded hole 17 and the first port 10. Thus a portion of the oil supply duct terminating at and connected to the oil jacket is disposed between the at least an exhaust port 10 ■ and the threaded hole 17. Hence, the oil supply duct 32 is disposed substantially farther from the second port 9 and the third port 13. It is to be noted that temperatue near the exhaust port is always higher than the temperature near the intake ports. Hence, the aforementioned entry of the oil supply duct 32 closer to the the first port 10 helps in immediate cooling of the portion of the cylinder head 2 above the combustion chamber. After the oil enters the oil jacket 40, it flows to all areas of the oil jacket 40 as shown by the arrows in FIG. 5. It immediately cools the combustion chamber 6 and flows towards the area around the threaded hole 17 and the area around the first port 10.
[00029] The oil jacket 40 comprises atleast two integrally formed oil
dumping zones namely a first oil dumping zone 45 and a second oil dumping zone 46 through which the oil from the oil jacket 40 moves from the cylinder head 2
r
toward the cylinder block 3 as shown in FIG. 6. The first oil dumping zone 45 is

disposed opposite to the second oil dumping zone 46. Thus, the second oil dumping zone 46 is located closer to the threaded hole 17 accomodating the ignition device 15 than the first oil dumping zone 45. The oil dumping zones are downwardly oriented so that the oil after exiting from the oil supply duct 32 and travelling across the oil jacket 40 is collected in either of the oil dumping zone. The first oil dumping zone 45 and the second oil dumping zone 46 are further connected to a head groove 62. The head groove 62 is an endless annular groove having a radius more than that of the cylinder bore 20. It is disposed at a bottom surface of the cylinder head 2 joined to a top surface of the cylinder block 3. The oil jacket 40 is connected to the head groove 62 through the oil dumping zones 45, 46.
[00030] The cylinder head 2 and the cylinder block 3 are sealed during the
engine assembly to prevent any leak during the engine operation. As shown in FIG. 7, a sealing member 55 is interposed at the interface of the cylinder head 2 and the cylinder block 3 to seal the two during engine assembly. The sealing member 55 is symmetrical to the.bottom surface of the cylinder head 2. An upper surface of the sealing member 55 is in contact with the bottom surface of the cylinder head 2 and a lower surface of the sealing member 55 is in contact with the upper surface of the cylinder block 3. It comprises of a centrally formed annular bore opening 56 for accomodating the cylinder bore 20 and at least one link opening. In an embodiment, the sealing member 55 has two link openings 57-. 1, 57-2 spaced apart from each other.

[00031] FIG. 8 shows a top view of the cylinder block 3. A cast iron
cylinder liner 19 is provided between the cylinder bore 20 and the cylinder block 3 so that the cylinder bore 20 is not deformed during the continuous reciprocatory motion of the piston 5. A block groove 64 is formed radially outwardly of the cylinder block 20. It circles the cylinder block 3 and is protruded at one end to form a drain channel 65.
[00032] During the engine assembly, the cylinder block 3 is positioned
below the cylinder head 2. The head groove 62 is co-axial to the block groove 64 (FIG. 6). The head groove 62 and the block groove 64 are disposed radially outwardly at a certain distance from the bore surface to reduce the possibility of the oil leaking into the combustion chamber 6. However, when assembled, the head groove 62 and block groove 64 are not continuously connected. Instead, the link openings 57-1, 57-2 of the sealing member 55, located between the cylinder block 3 and the cylinder head 2, connect the head groove 62 with the block groove 64.
[00033] The oil received in the oil jacket 40 is thus drained toward the
cylinder block 3 and the same is explained using FIG. 6-8. Firstly, after circulation around the oil jacket 40, the oil moves toward the first oil dumping zone 45 and the second oil dumping zone 46 which are connected to the head groove 62. The oil circulates in the head groove 62 in a circular fashion and through the link openings 57-1, 57-2 of the sealing member 55 flows into the block groove 64. The oil circulates around the block groove 64 and then exits from the drain channel 65 towards a cam chain opening 18. The cam chain

opening 18 is further connected to the oil sump 70. The cam chain opening 18 is provided for the rotation of the endless cam chain which connects the cam shaft 14 with the crankshaft 8. The heat is thus removed by the oil from the combustion chamber 6 and surrounding components to the oil sump 70.
[00034] Further, the oil in the oil jacket prevents the combustion noise
emanating from the combustion chamber by acting as a barrier to the spread of the noise upwardly to the top portion of the cylinder head. The oil as a medium dampens the noise waves and weakens their strength.
[00035] The concepts of the present invention are fully usable in another
type of IC engine having at least four ports out of which two ports are configured to function as intake ports and two other ports are configured to function as exhaust ports. In this engine configuration, the two intake ports are located on one side of the plane that longitudinally divides the cylinder bore into two halves. The two exhaust ports are disposed on the other side of the said plane. Due to lack of space in this configuration, the threaded hole for accomodating the ignition device is disposed centrally to the cylinde bore so that it acts as an intersection of diagonals of a square having at least one port at each of its corners. In such engine, an oil jacket is disposed substantially in a portion of the cylinder head above the combustion chamber. It facilitates cooling of the combustion chamber and dampens the combustion noise emanating from the combustion chamber. The oil jacket receives oil from a stud hole through an oil supply duct as explained above. Specifically, the oil supply duct is disposed adjacent to least one exhaust

port i.e. the first port. The oil circulates into oil jacket and drains out through a drain channel in the cylinder block.
[00036] The portion of the cylinder head above the combustion chamber
has space constraints in a four valve engine. Therefore, the oil jacket is disposed in the space between the two intake valves. ;and the two exhaust valves. It substantially surrounds the ignition device and channels the oil out from between the threaded hole and one of the intake ports. Due to this, the heat is quickly removed from the combustion chamber during the oil circulation.
[00037] From the foregoing description, it will be appreciated that the
present invention offers many advantages including those described above. The oil cools the combustion chamber and the ignition device. The entry of the oil into the oil jacket near the exhaust port is effective as the area around the exhaust port has the highest temperature within the combustion chamber. Further, the oil jacket helps in cooling as well as supresses engine noise by use of oil acting as damping medium. It is to be noted that the oil can be any lubricating oil.
[00038] The present subject matter is thus described. The description is not
-intended to be exhaustive nor is it intended to limit the invention to the precise form disclosed. It will be apparent to those skilled in the art that the disclosed embodiments may be modified in light of the above description. The embodiments described are chosen to provide an illustration of principles of the invention and its practical application to enable thereby one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore the forgoing description is to be considered exemplary, rather than limiting, and the true scope of the invention is that described in the appended claims

We claim:
1. An internal combustion engine comprising:
a crankcase (4) supporting a crank shaft (8)5 said crankcase further comprising an oil sump (70) storing a predetermined volume of oil;
a cylinder block (3) connected to the crankcase (4) having a centrally formed cylinder bore (20) allowing a piston (5) connected to the crank shaft (8) to move slidably inside said cylinder bore (20);
a cylinder head (2) connected to said cylinder block (3), wherein said cylinder head (2) includes at least two intake ports (9,13), at least one -exhaust port (10), and at least one threaded hole (17) for accommodating an ignition device (15);
a combustion chamber (6) formed above said cylinder bore (20) in a space between the cylinder head (2) and the cylinder block (3) for receiving fuel air mixture through said at least two intake ports (9,13); and
at least one stud hole (30) passing through the cylinder block (3) towards a top portion of the cylinder head (2) and allowing passage of oil from the oil sump (70) to the cylinder head (2);
wherein the oil from the stud hole (30) enters the cylinder head (2) through at least one oil supply duct (32) disposed adjacent to said at least, one exhaust port (10), and wherein the at least one oil supply duct (32) terminates at an oil jacket (40) disposed substantially above the

combustion chamber (6) for cooling the combustion chamber and dampening a combustion noise dissipated by said combustion chamber.
2. The internal combustion engine as claimed in claim 1, wherein a portion of the oil supply duct (32) terminating at the oil jacket (40) is disposed between the at least one exhaust port (10) and the threaded hole (17).
3. The internal combustion engine as claimed in claim 1, wherein the oil supply duct (32) is disposed substantially farther from the at least two intake ports (9,13).
4. The internal combustion engine as claimed in claim 1, wherein said oil jacket (40) is disposed substantially surrounding the ignition device (15), such that the passage of oil in the oil jacket (40) absorbs the heat dissipated by the ignition device (15).
5. The internal combustion engine as claimed in claim 1, wherein said oil jacket (40) is disposed substantially surrounding the at. least one exhaust port (10), such that the passage of oil in the oil jacket (40) absorbs the heat dissipated by the at least one exhaust port (10).
6. The internal combustion engine as claimed in claim 1, wherein the oil from the oil jacket (40) enters the cylinder block (3) through a head groove (62) and a block groove (64).
7. The internal combustion engine as claimed in claim 6, wherein the head groove and the block groove are disposed substantially around the cylinder

bore and wherein the block groove is protruded at one end to form a drain channel (65)
8. The internal combustion engine as claimed in claim 1, wherein the cylinder head (2) and the cylinder block (3) are separated by means of at least one sealing member (5) having at least two link openings (57-1, 57-2).
9. The internal combustion engine as claimed in claim 1, wherein the ignition device (15) and the oil supply duct (32) are disposed substantially inclined to a central axis of said cylinder bore (20).
10. The internal combustion engine as claimed in claim 1, wherein the at least one threaded hole (17) for accommodating the ignition device (15) and the at least one exhaust port (10) are disposed on one side of a plane (Y-Y') that longitudinally divides the cylinder bore (20) into two halves, and wherein the at least two intake ports (9, 13) are disposed on other side of said plane.