DESC:FIELD OF INVENTION
[001] The present invention relates to a cooling system for an engine of a vehicle and more particularly relates to an oil based cooling system.
BACKGROUND OF INVENTION
[002] An engine is a primary component of fuel operated vehicle responsible for driving the vehicle. Thermal characteristics of the engine are major contributors for effective performance of the engine, which is achieved using different cooling techniques. In automotive industry, various types of cooling arrangement are employed for an internal combustion engine in order to safeguard it from adverse effects of high heat generated in combustion chambers and maintain it under the properly determined temperature conditions for its efficient operation.

[003] The conventional cooling arrangements are broadly classified into air cooled engines, oil cooled engines and liquid cooled engines. The air cooled engine uses fins provided on the outer surface of the engine, thereby the passing of air through the fins aid into cooling the engine. The oil cooled engine uses oil which is circulated within the engine for cooling purpose. The oil takes away heat from the heated part of the engine. The liquid cooled engines utilizes circulation of coolant through internal channels of the engine. The coolant absorbs heat from the engine and is pumped through a radiator which cools down the coolant.

[004] Generally, oil cooled engines are used for higher performance bikes having mid to high capacity engines i.e. above 100 cc engines. The arrangement utilizes oil galleries and oil passages in engine through which the oil is circulated to extract heat from the heated parts of the engine. The oil is circulated through a set of passage in the engine to radiator placed external to the engine, subsequently, the oil is cooled by exchanging heat with the atmospheric air. The process is repeated by recirculation of the cooled oil through the passages of the engine and hence the engine temperature is maintained, at the same time oil viscosity is maintained.

[005] As stated, the existing oil cooled engine includes set of oil cooling channels around the cylinder head, particularly above the combustion chamber i.e. on the top surface of the combustion chamber in the cylinder head. The oil cooling channels are distributed in the cylinder head. However, by this technique the temperature rise in the cylinder head is not uniformly maintained since a variation in the temperature gradient exists in certain areas of the engine. For example, area under the spark plug mounting and area around the valve seats are the areas where high temperature gradient is observed being closer to combustion chamber. These high heat zones are in confined spaces and it is difficult to provide a cooling passage or chamber just above the combustion chamber since that area is highly crowded with valve seats, also in case of spark plug, the available space is insufficient to properly channelize any oil cooling passage. Hence the existing oil cooling arrangement fails to effectively extract heat from these areas and leads to hampering the overall thermal performance of the engine.

[006] In order to address the above concerns a machined through hole is provided in a tower wall of the cylinder head of the engine. The machined through hole facilitates the oil supply in the stated confined area. However, the proposed design including through-hole in the cylinder head affects the physical integrity of the cylinder head. Further, mere supplying the oil over the heated area doesn’t result in effective heat extraction and hence the thermal performance of the engine is severely hampered.

[007] The engine provided with single cylinder includes at least four valves distributed symmetrically about the central axis of the combustion chamber of the engine wherein, at least two valves are inlet valve configured to supply fuel to the combustion chamber and at least two valve are exhaust valves configured to discharge the gases of combusted fuel and at least one spark plug is mounted in the cylinder head. The spark plug is mounted in direction perpendicular to the line in which inlet or exhaust valves are mounted. The stated components namely multiple valves and spark plug forms a crowded area in the cylinder head i.e. above the combustion chamber. Consequently, the high heat generated in the combustion chamber is not properly dissipated, since there is inadequate space available to provide efficient cooling in the single cylinder engine.

[008] Considering the above conditions and challenges faced, there is a need to re-design the cooling arrangement in the cylinder head, which can solve the above stated problems without compromising the cylinder head integrity and rigidity. The cooling system for the engine should be such that it can provide proper heat extraction from the high temperature zones of the engine and ensure efficient thermal performance of the engine.

OBJECTIVES OF INVENTION
[009] It is an object of the present invention to provide an oil cooling system in an engine for improved thermal management.

[010] Another objective of the present invention is to provide effective cooling near high temperature zones of the cylinder head.

[011] Another objective of the present invention is to provide cooling system for engine without compromising on the cylinder head integrity and rigidity.

[012] Yet another objective of the present invention is to effectively cool the areas in engine having variable thermal gradient.

[013] Another objective of the present invention is to provide effective cooling system for single cylinder engine.

[014] Another objective of the present invention is to provide effective cooling system for single cylinder with multiple valves.

[015] Another objective of the present invention is to provide effective cooling system for single cylinder with multiple valves having at least one spark plug.

[016] Other objects and advantages of the present disclosure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure.

SUMMARY OF INVENTION
[017] With these objectives in view, the present invention provides an oil based cooling system for an engine of a vehicle, comprising:
a cylinder block located in a lower portion of the engine including a combustion chamber;
a crankcase located in the lower portion of the engine and connected to the lower part of the cylinder block;
a cylinder head located in an upper portion of the engine and mounted at top surface of the cylinder block;
the cylinder head including a cam shaft, at least a spark plug mounting area and a valve seat surface provided below the cam shaft for resting at least two valves operated through the cam shaft ;
wherein, a cooling chamber is formed between the cam shaft and the valve seat surface and provided with at least an oil jet for injecting cooling oil towards the cooling chamber to extract heat around the valve seat surface.

[018] According to one of the embodiments, the cooling chamber includes plurality of surfaces and at least an opening. Preferably, the cooling chamber has the opening towards the cam chain chamber provided on one side of the engine.

[019] The cooling chamber is provided with at least a surface having protrusions to increase the surface area, thereby increasing turbulence and enhancing heat transfer of the cooling oil. Preferably, lower surface of the cooling chamber above the valve seat and spark plug is provided with protrusions to enhance the heat transfer.

[020] The lower surface of the cooling chamber slopes downward towards the cam chain chamber for ease of oil flow towards the cam chain chamber.

[021] According to one of the embodiments, at least the oil jet is formed with converging cross-section towards discharge of the oil jet.

[022] According to one of the embodiments, the cooling oil transmits from the crankcase to the cylinder head through a stud hole and an oil gallery. The stud hole is provided in the cylinder block and the cylinder head and the oil gallery is provided in the cylinder head. The crankcase includes oil passage configured to transmit oil from the oil sump to the stud hole utilizing an oil pump. The oil gallery provided in the cylinder head includes a horizontal passage above the cooling chamber and in perpendicular direction to the cam shaft transmitting cooling oil to the oil jets.

[023] According to another embodiments, an oil cooler is configured to cool the extracted oil from the oil sump provided with a fan to enhance the efficacy of oil cooling.

[024] According to one of the embodiments, the cylinder head is provided with a set of air fins or guides around spark plug mounting area for cooling the engine.

[025] The oil based cooling system according to the present invention is employed on any vehicle including two-wheeled, three-wheeled and four-wheeled vehicles.

[026] The oil based cooling system according to the present invention is employed to single cylinder engine.
BRIEF DESCRPTION OF DRAWINGS
[027] The above and other objects, features, and advantage of the present disclosure will be more apparent from the detailed description taken in conjunction with the accompanying drawings. One or more embodiments of the present invention are now described, by the way of example only with reference to the accompanied drawings wherein like reference numerals represent like elements:

[028] Fig. 1 illustrates an engine employed with oil based cooling system, according to an embodiment of the present disclosure;

[029] Fig. 2 illustrates the top view of a cylinder head, according to an embodiment of the present disclosure;

[030] Figs. 3a and 3b illustrate sections A-A and B-B of the cylinder head as shown in Fig. 2, according to an embodiment of the present disclosure;

[031] Fig. 4 illustrates a sectional view B-B of the cylinder head as shown in Fig. 3b, according to an embodiment of the present disclosure;

[032] Fig. 5 illustrates sectional view C-C of the cylinder head along with cylinder block of the engine, according to an embodiment of the present disclosure;

DETAIL DESCRIPTION OF DRAWINGS
[033] A preferred embodiment will now be described in detail with reference to the accompanying drawings. The preferred embodiment does not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.

[034] It will be readily understood that components of present invention as generally described and illustrated in figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention as represented in the figures is not intended to limit the scope of the invention but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention. The presently described embodiments will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.

[035] Fig. 1 illustrates an engine (100) for a vehicle provided with a cylinder block (102) and a cylinder head (108). The cylinder block (102) located in a lower portion (100a) of the engine (100) comprises of a combustion chamber (104) and a crankcase (106) onto which the cylinder block (102) is mounted. The cylinder block (102) is located in the lower portion (100a) of the engine (100). The cylinder head (108) is located in an upper portion (100b) of the engine (100) and is mounted at top surface of the cylinder block (102). The cylinder head (108) comprises of a cam shaft (110), a cam chain chamber (112) and a valve seat surface (114) for resting at least two valves (namely intake valve and exhaust valve) (116, 118), and a spark plug (not shown). The cylinder head (108) and the cylinder block (102) are provided with a head gasket (132) placed between them for a leak-proof arrangement. In present embodiment, the engine (100) uses a SOHC (single overhead camshaft) arrangement, wherein two intake valves (116) and two exhaust valves (118) are used. The cam shaft (110) governs the opening and closing of all the four valve (116, 118). The spark plug is mounted in a direction perpendicular to the line in which the intake valves (116) or the exhaust valves (118) are mounted. In a top view of the engine (100), the spark plug is mounted on the side opposite to the cam chain chamber (112). An oil based cooling system is provided in the cylinder head (108) of the engine (100) which is a single-cylinder engine (100) equipped with the SOHC arrangement.

[036] Fig. 2 illustrates a top view of the cylinder head (108), when the upper structure of the cylinder head (108) is removed, having cam shaft (110) rotatably fixed on the walls of the cylinder head (108) through bearing to adjust the valve operations. The engine (100) includes an intake opening (120) for connecting with an intake system of the vehicle (not shown) and an exhaust port (122) for connecting with an exhaust system of the vehicle (not shown). The valves namely intake valves (116) and exhaust valves (118) rest on a valve seat surface (114). The plurality of intake valves (116) rotatably engaged with cams mounted on the cam shaft (110) to actuate the intake valves (116) as per the requirement and pre-defined timings. Similarly, the plurality of exhaust valves (118) rotatably engaged with cams mounted on the cam shaft (110) to actuate the exhaust valves (118) as per the requirement and pre-defined timings. Notably, all the four cams for actuating the valves (116, 118) are mounted on single cam shaft (110). The intake and exhaust sides are located on opposite direction as of the cam shaft (110). As per the configuration, the spark plug mounting area (124) is provided in perpendicular direction to the line of the cam shaft (110) central axis (X-X) and the cam chain chamber (112) is positioned on the other side of the cam shaft (110). The valve seat surface (114) is a crowded area with numerous mountings arrangements and hence effective cooling under the valve seat surface (114) is of concern since combustion chamber (104) is situated under the valve seat surface (114) and the heat gradient at the valve seat surface (114) is high.

[037] Figs. 3a and 3b illustrate sectional views A-A and B-B of the cylinder head (108) as shown in Fig. 2. In a preferred embodiment, the oil based cooling system provided in the cylinder head (108) is equipped with a cooling chamber (126) to extract heat around the valve seat surface (114). The cooling chamber (126) is a designated space formed between the cam shaft (110) and the valve seat surface (114) using predefined manufacturing processes. The cooling chamber (126) is formed of plurality of side surfaces (126a), an upper surface (126b) and a lower surface (126c). The cooling chamber (126) is majorly formed on one side of central axis of the engine (100) as viewed in section B-B. The cooling chamber (126) has an opening (126d) which is formed on the cam chain chamber (112) side. The opposite end to the opening (126d) in the cooling chamber (126) is a slanted surface (126e) which is positioned to facilitate in spark plug mounting area (124). The lower surface (126c) above the valve seat surface (114) is provided with protrusions (130) to increase the surface area of the lower surface (126c), thereby increasing the heat transfer from the lower surface (126c).

[038] Fig. 4 illustrates a sectional view B-B of the cylinder head (108) as shown in Fig. 3b. In a preferred embodiment, the oil based cooling system provided with at least an oil jet (128) positioned on the wall (W) of the cylinder head (108) forming the cam chain chamber (112). Preferably, there are two oil jets (128) in the given arrangement. The oil jet (128) directs the cooling oil towards the extreme end of the lower surface (126c) i.e. closer to the central axis of the engine (100). The oil jet (128) is manufactured with tapered profile i.e. the diameter of the oil jet decreases towards the discharge (D’). The diameter of the oil jet (128) at the discharge is “d” which is smaller than the diameter of the oil jet (128) i.e. “D”. The decreasing diameter of the oil jet (128) increases the velocity of cooling oil and hence the oil is targeted at the farthest location. The lower surface (126c) of the cooling chamber provided with protrusions (130) aids in high heat transfer and create turbulent flow of cooling oil which further aids in improved heat transfer. The cooling oil trickles through the sloping downward lower surface (126c) of the cooling chamber towards the cam chain chamber (112) for ease of oil flow towards the cam chain chamber (112). The continuous flow of cooling oil through the oil jet (128) towards the cooling surface and proper re-circulation ensures efficient heat transfer from the high heat gradient zone i.e., combustion chamber (104), cylinder head (108), and spark plug mounting area (124).

[039] Fig. 5 illustrates a sectional view C-C of the cylinder head (108) along with cylinder block (102). In a preferred embodiment, the oil based cooling system provided a proper passage for supplying the cooling oil in the cooling chamber (126) of the cylinder head (108). The oil injected on the cooling chamber (126) extracts the heat from the cooling chamber (126) and trickles down through the sloping downward lower surface (126c) of the cooling chamber (126). The oil flows through the cam chain chamber (112) to the crankcase (106), thereafter the oil is conveyed to external heat transfer device, wherein a fan is employed to cool the extracted oil from the oil sump (S) and improves the oil cooling efficacy. Alternatively, an oil cooler or a radiator may be provided for cooling the extracted oil. Thereafter, the oil returns to the crankcase (106) and then cleaned through a strainer and recirculated. The cooling oil passes through an oil passage transmitting oil from the crankcase (106) to the cylinder head (108). The oil passage includes oil channels and internal pockets (not shown) provided in the crankcase (106), a stud provided in the cylinder block (102) and an oil gallery (136) provided in cylinder head (108). The cooling oil from the sump (S) provided in the crankcase (106) is transmitted to the internal pockets of the crankcase (106) utilizing an oil pump (P). The internal pockets of the crankcase (106) connect with the stud, wherein the stud include stud hole (134) transmitting oil to the cylinder block (102) and thereafter to the cylinder head (108) through the oil gallery (136). The oil gallery (136) of the cylinder head (108) includes a horizontal passage on the cylinder wall (W) above the cooling chamber (126) and in perpendicular direction to the cam shaft (110) providing pathway for oil reaching the oil jet (128). Thereafter, the flow cycle of the cooling oil repeats and continuous heat transfer from the cooling chamber (126) occurs and the zone of combustion chamber (104) and spark plug mounting area (124) having high heat temperature gradient is effectively cooled and eventually working condition of the engine (100) is improved.

[040] Additionally, the cylinder head (108) is provided with a set of air guides or in the form of channels to navigate the atmospheric air towards the heated area in the cylinder head (108). The air guides specifically aid in cooling the area around spark plug mounting area (124). The air guides transfer the heat to the atmosphere through the fins provided on the cylinder head (108).

[041] The combination of oil based cooling and air cooling eventually improves the heat transfer from the cylinder head (108) and maintains the temperature of the cylinder in the operable range. The areas where the temperature rise is high are cooled by cooling oil jets (128), while the heat-affected area around the spark plug mounting area (124) is cooled by oil cooling along with air cooling.

[042] The present invention is applicable to any type of vehicle including two-wheeled, three wheeled or four wheeled vehicle including single cylinder and multi-cylinder engine.

[043] The present invention may be embodied in other specific forms without departing from its spirit or essential characteristics or essential characteristics. The described embodiments are to be considered in respects as illustrative and not restrictive.

[044] Although the exemplary forms of the present disclosure have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the present disclosure.

List of Reference Numerals:
100 – Engine
100a – Engine lower portion
100b - Engine upper portion
102 – Cylinder block
104 – Combustion chamber
106 – Crankcase
108 - Cylinder head
110 - Camshaft
112 - Cam chain chamber
114 - Valve seat surface
116 - Intake valves
118 - Exhaust valves
120 – Intake opening
122 – Exhaust port
124 - Spark plug mounting area
126 - Cooling chamber
126a – Plurality of side surfaces
126b - Upper surface
126c - Lower surface
126d – Opening
126e – Slanted surface
128 - Oil jet
130 - Protrusions
132 – Gasket
134 – Stud hole
136 – Oil gallery
P – Pump
S - Sump
D’ - Discharge
D – Large Diameter of oil jet
d – Small Diameter of oil jet
W – Wall of Cylinder head
,CLAIMS:1. An oil based cooling system for an engine (100) of a vehicle, comprising:
a cylinder block (102) including a combustion chamber (104);
a crankcase (106) connected to a lower part of the cylinder block (102);
a cylinder head (108) mounted at a top surface of the cylinder block (102);
the cylinder head (108) including a cam shaft (110), at least a spark plug mounting area (124) and a valve seat surface (114) provided below the cam shaft (110) for resting at least two valves (116, 118) operated through the cam shaft (110);
wherein, a cooling chamber (126) is formed between the cam shaft (110) and the valve seat surface (114) and provided with at least an oil jet (128) for injecting cooling oil towards the cooling chamber (126) to extract heat around the valve seat surface (114).
2. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 1, wherein the cooling chamber (126) includes a plurality of surfaces (126a, 126b, 126c, 126e) and at least an opening (126d) towards a cam chain chamber (112) provided on one side of the engine (100).
3. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 2, wherein the cooling chamber (126) having a lower surface (126c) above the valve seat surface (114) is provided with protrusions (130) to enhance the heat transfer.
4. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 3, wherein the lower surface (126c) of the cooling chamber (126) slopes downward towards the cam chain chamber (112) for ease of oil flow towards the cam chain chamber (112).
5. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 1, wherein the oil jet (128) is formed with converging cross-section towards discharge of the oil jet (128).
6. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 1, wherein the cooling oil transmits from the crankcase (106) to the cylinder head (108) through a stud hole (134) provided to connect the cylinder block (102) and the cylinder head (108) and an oil gallery (136) provided in the cylinder head (108).
7. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 6, wherein the crankcase (106) includes oil passage configured to transmit oil from the oil sump (S) to the stud hole (134) utilizing an oil pump (P).
8. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 7, wherein the oil gallery provided (136) in the cylinder head (108) includes a horizontal passage located above the cooling chamber (126) and oriented perpendicular to the cam shaft (110), for delivering cooling oil to the oil jet (128).
9. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 6, wherein an oil cooler is configured to cool the extracted oil from the oil sump, is equipped with a fan.
10. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 1, wherein the cylinder head (108) is provided with a set of fins towards the spark plug mounting area (124).
11. The oil based cooling system for the engine (100) of the vehicle as claimed in claim 1, wherein the engine (100) is a single cylinder engine.