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 a cooling channel for a four cycle internal combustion engine.
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 said engine, among other components, has a cylinder comprising a cylinder head atop or in front of the cylinder and receiving a reciprocating piston from the bottom or the rear. On combustion of the air-fuel mixture, the piston transfers the energy generated during combustion to a crankshaft through a connecting rod thereby driving the crankshaft. In this way, the reciprocatory motion of the piston is converted to rotatory motion of the crankshaft. The crankshaft is housed inside a crankcase beneath or behind the cylinder block.
[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 in 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. The combustion chamber also 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 and costly due to presence of radiator and other supporting elements and also occupy usable space in the overall layout of the vehicle having such engine.
SUMMARY OF THE INVENTION
[0005] Therefore, a need exists to effectively cool the combustion
chamber as well as cylinder head of the four cycle internal combustion engine without incurring high cost. It is therefore an object of the present invention to provide an internal combustion engine having improved cooling for the cylinder head and other surrounding components, particularly the combustion chamber.
[0006] To this end, the present invention discloses an internal combustion
engine comprising a cylinder block coupled to a crankcase, a cylinder head coupled to an upper portion of the cylinder block and a sealing member interposed at the interface of the cylinder block and the cylinder head. The internal combustion engine also includes a cooling channel comprising a lower vertical passage formed in the cylinder block, an upper vertical passage formed in the
cylinder head, a head groove formed at the bottom surface of the cylinder head, a block groove co-axial with and symmetrical to the head groove formed at the top surface of the cylinder block. According to an aspect, the head groove and the block groove together develop into a cooling groove which cools the cylinder head.
[0007] The cooling groove preferably surrounds the combustion chamber
and the oil which flows into the cooling channel, of which cooling groove is a part, carries away a portion of the heat generated in the combustion chamber thus cooling the engine.
[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 DRAWINGS
[0009] The above and other features, aspects and advantages of the subject
matter will be better understood with regard to the following description, appended claims 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 cooling channel in a four cycle internal combustion
engine according to the present invention.
[00012] FIG. 3 shows a sectional view of the cooling channel according to
the present invention.
[00013] FIG. 4 shows a sectional view of the cooling channel.
[00014] FIG. 5 shows a sectional view of a lower portion of the cylinder
Tiead having" a~B"otfoWsWface7
[00015] FIG. 6 shows a sectional view of the top portion of the cylinder
block having, a top surface.
[00016] FIG. 7 shows a sectional view of the cylinder head.
DETAILED DESCRIPTION OF THE INVENTION
[00017] 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. In an embodiment, the engine is a multi-valve engine. In a preferred embodiment, the 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.
[00018] 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 the cylinder block 3. In a vertical engine like the one shown here, the cylinder head 2 is 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 80 allowing a
reciprocating piston 5 to move slidably within the cylinder bore 80. 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.
[00019] The cylinder head 2 comprises of at least two ports, namely a first
port 10 and a second port 9 which communicate with a combustion chamber 6 formed by being surrounded by the cylinder bore 80, 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.
[00020] 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] According to an embodiment of the present invention, the engine is
a multi-valve engine wherein the cylinder head 2 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. According to a preferred embodiment, out of the three ports, the cylinder head 2 has at least two intake ports (9 being visible in FIG. 1) and at least one exhaust port 10.
[00022] 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. 3, 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.
[00023] The internal combustion engine further includes a cooling channel
20. As shown in FIG. 2 and FIG. 3, the cylinder head 2 and the cylinder block 3 are configured to allow the cooling channel 20 to pass through. The cooling channel 20 comprises of a lower vertical passage 21 formed in the cylinder block 3, an upper vertical passage 22 formed in the cylinder head 2, the upper vertical passage 22 connected to the lower vertical passage 21 through a cooling groove 23 for cooling a combustion chamber 6. The cooling groove 23 further includes a head groove 62 formed at the bottom surface of the cylinder head 2 and a block groove 64 co-axial with and symmetrical to the head groove 62 and formed at the top surface of the cylinder block 3. The head groove 62 is an endless annular groove having a radius more than that of the cylinder bore 80. It is disposed at the bottom surface of the cylinder head 2 joined to the top surface of the cylinder block 3. Likewise, the block groove 64 is formed radially outwardly of the cylinder bore 80
[00024] During engine assembly, the head groove 62 and the block groove
64 form an interface and develop into the cooling groove 23 of a predetermined width at the interface of the cylinder block 3 and the cylinder head 2. The cooling groove 23 substantially circles around the combustion chamber 6 when seen in the top sectional view and has an entry end 26 and an exit end 27 as shown in FIG. 4 and FIG. 5. In an embodiment, the entry end 26 and the exit end 27 are spaced apart and hence the cooling groove 23 does not completely circles the combustion
chamber 6. The cooling groove 23 is thus not continuous around the combustion chamber 6. As shown in FIG. 3, the entry end 26 is continuously connected to the lower vertical passage 21 and the exit end 27 is continuously connected to the upper vertical passage 22.
[00025] The sealing member 55 is configured to seal the interface of the
cylinder head and the cylinder block to prevent any oil leak. Since the sealing member 55 is present at the interface of the cylinder head 2 and the cylinder block 3, to ensure oil flow from the block groove 64 to the head groove 62, the sealing member 55 is provided with a link opening due to which the head groove and the block groove are fluidly connected. The link opening corresponds to the cooling groove 23. As is commonly known, to ensure the strength of the sealing member, a plurality of bridges are provided in the link opening due to which the link opening is divided into a plurality of sub opening. The bridge enhances the life of the sealing member. Further, to ensure effective sealing the sealing member is provided with an embossing along the link opening. The embossing pressure seals the mating surfaces of the cylinder head and the cylinder block and keeps the combustion chamber away from the cooling groove.
[00026] As shown in FIG. 4, the lower vertical passage 21 and the upper
vertical passage 22 have a cylindrical cross section with small diameter which ensures that the oil is sufficiently pumped towards the cylinder head 2. The cooling groove 23 helps in engine cooling, particularly the combustion chamber, as well as suppresses engine noise by use of oil acting as damping medium. It also suppresses combustion noise in the cylinder head.
[00027] The working of cooling channel is now explained. During the
operation of the engine 1, significant heat is generated within the combustion chamber 6 which should be dissipated for efficient functioning of the engine 1. The components proximate to the combustion chamber 6 are also exposed to high temperatures. Therefore, the atmospheric air blowing towards the engine 1 is used to cool the cylinder head 2. A plurality of fins are provided on the outer surface of the upper portion of the engine 1 including that of cylinder head 2 and cylinder block 3. The air however cools only the outer surface of the engine 1. Therefore, the engine 1 is provided with the cooling channel as described for carrying away the heat generated to the outer surface of the engine which then gets cooled through the environmental air. The lubrication oil present in the crankcase is pressured to go upwards by an oil pump through a nozzle 24. The nozzle 24 channelizes the oil into the lower vertical passage 21 which extends from a lower portion of the cylinder block to the top surface of cylinder block. The lower vertical oil passage 21 is connected to the entry end 26 of the cooling groove 23 approximately circling the combustion chamber 6 at the upper portion of the cylinder block 3. The cooling groove 23 is also connected to the upper vertical passage 22 located opposed to the lower vertical passage 21. The oil after circling the cooling groove 23 enters the upper vertical passage 22 through the exit end 27 from where the oil is routed to the camshaft cavity as the bearing cavity is closed. As shown in FIG. 7, due to the centrifugal force of the camshaft 14, the oil is thrown outwards by the through holes made into the intake and exhaust lobes. The oil now lubricates the roller of the rocker arm and falls from the other end of the
camshaft cavity. From the other end of the camshaft, the oil comes down to the oil sump via the cam chain.
[00028] Thus, in high compression engines, significant heat generated in
the combustion chamber is absorbed by the oil circling in the cooling groove 23. The cooling channel 20 thus assists in the heat rejection from and around the combustion chamber 6 as well as lubricates the cylinder head components. It is to be noted that the oil can be anv.lubricating oil.
[00029] According to an aspect, the lower vertical passage 21 is offset to
the upper vertical passage 22 when seen in a side sectional view. Both are not directly connected to each other. When seen in a side view, the lower vertical passage is not in the same line as the upper vertical passage It is leftward to the upper vertical passage and is connected to it by the cooling groove 23.
[00030] Further, the head groove has sufficient depth to carry oil in the
range of 5-8 mm. The block groove has an identical depth. The width of the cooling groove is in the range of 3-8 mm. Likewise, the lower and upper vertical passage has a diameter in the range of 4-8 mm so that the oil is pumped easily up to the cylinder head. According to another feature of the invention, the ratio of diameter of cylinder bore 80 to the starting diameter of the cooling groove 23 is in the range between 0.75 to 0.85. The starting diameter of the cooling groove does not include the width of the cooling groove itself and is measured with the cylinder bore axis as the centre. This ratio ensures that the cooling groove 23 is radially outwardly at a certain distance from the bore surface to reduce the possibility of the oil leaking into the combustion chamber 6.
[00031] It is to be noted that the upper vertical passage and the lower
vertical passage are not necessarily parallel to the cylinder bore axis and include a
passage disposed angularly with respect to the cylinder bore axis. 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:
An internal combustion engine (1) comprising a cylinder block (3) coupled to a crankcase (4), a cylinder head (2) coupled to the cylinder block (3), a sealing member (55) interposed at the interface of the cylinder block (3) and the cylinder head (2), wherein the internal combustion engine also includes a cooling channel (20) comprising a lower vertical passage (21) formed in the cylinder block (3), an upper vertical passage (22) formed in the cylinder head (2) and a cooling groove (23), the upper vertical passage (22) connected to the lower vertical passage (21) through the cooling groove (23) for cooling a combustion chamber (6) wherein the cooling groove (23) includes a head groove (62) formed at the bottom surface of the cylinder head (2) and a block groove (64) co-axial with and symmetrical to the head groove (62) and formed at the top surface of the cylinder block (3).
The internal combustion engine as claimed in claim 1, wherein the cooling groove (23) substantially circles around the combustion chamber (6) when seen in a top sectional view and has an entry end (26) continuously connected to one end of the lower vertical passage (21) and an exit end (27) continuously connected to one end of the upper vertical passage (22).
The internal combustion engine as claimed in claim 1, wherein the block groove (64) is fluidly connected to the head groove (62) through the sealing member (55).
The internal combustion engine as claimed in claim 1, wherein the lower vertical passage (21) is offset to the upper vertical passage (22) when seen in a side sectional view.
The internal combustion engine as claimed in claim 1, wherein the ratio of diameter of a cylinder bore (80) to the starting diameter of the cooling groove (23) is in the range between 0.75 to 0.85.
_6.The internal-combustion-engine-as~claimed4n-any-of thepreceding; claim,— wherein the internal combustion engine is a three valve engine.