DESC:FIELD OF INVENTION
[0001] The present invention relates to an exhaust gas recirculation system enabled to reduce NOx from exhaust gases produced by an internal combustion engine and more particularly to a passage for exhaust gas recirculation which is formed within a cylinder head of said internal combustion engine.
BACKGROUND OF INVENTION
[0002] Generally, an internal combustion engine is functionally connected to a rear wheel of a vehicle to provide a motion to the vehicle. The internal combustion engine comprises of a cylinder bore where the combustion occurs to provide the needed power to the vehicle. The internal combustion (IC) engine, among other components, has a cylinder on top of which a cylinder head is mounted, and receives 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 rotary motion of the crankshaft. The crankshaft rotation then in turn powers the vehicle.
[0003] However, there are exhaust gases generated due to the combustion process occurring in the internal combustion engine. The exhaust gas generated after combustion in internal combustion engine is actually a combination of different gases like N2, CO2, CO, H2O, NO, and NO2 etc. Most of the gases generated like NO, and NO2 (combined called as NOx) are harmful and are considered as major pollutants. The exhaust gases generated leave the internal combustion engine through an exhaust port disposed on the cylinder head. An exhaust pipe is connected to the exhaust port, which carries the exhaust from the internal combustion, transferring it to the muffler region from where it is finally released into the atmosphere. Various mechanisms and devices are incorporated for treating of exhaust gases. One such element used is the catalytic converter which tries oxidizing the exhaust gases to convert it into harmless gasses. Another such mechanism is exhaust gas recirculation (EGR) which tries reducing the production of NOx (NO, and NO2) during combustion of air-fuel mixture.
[0004] Various mechanisms for EGR to reduce the NOx in the exhaust gases are already known. Some of the existing technology use secondary air injection (SAI), and some of them use optimized catalytic converter for treating exhaust gases coming out of the combustion chamber. This particular method of injecting secondary air can decrease the CO component, but on the other hand leads to high NOx emission. In one of the other known process EGR works by recirculation a portion of exhaust gasses generated by the internal combustion engine back to its cylinder. This dilutes the O2 in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures. In yet another known process, spark timing optimization with optimized EGR flow rates is used to reduce NOx while maintaining fuel consumption at a pre-determined level. In one of the other methods, the exhaust which being re-circulated through EGR process is advisable to cool to enhance the performance and reduce the amount of NOx being produced. However, the present known arts generally use an exterior system or a body which is filled with coolant and mounted over the engine to cool the exhaust to be used for EGR. In furtherance to it, some of the known arts use valves mounted on the internal combustion engine to control the EGR flow.
[0005] All the above mentioned known mechanisms require an extra mounted tapping to be added in the system which makes the whole arrangement bulky, complicated and prone to more failure modes. Such known arts make the whole system bulky, hard to maintain and expensive too. The extra tapping requires and extra mounting aspect which needs to be added on the internal combustion engine. The aspect of extra tapping comprises with the limited space available for the other existing elements. In addition to it, the mounted tapping leads to noise and vibration problems, and is not stable as well. The probability of breaking and other failure modes when extra tapping is mounted on the internal combustion engine is higher. This further adds to the manufacturing cost and introduces many failure points as well. As explained above, implementation of any known processes, be it SAI, spark timing optimization or optimized catalytic converters either make the system bulky and complicated or increase the probability of greater failure modes. All the above said technologies require loads of maintenance as well. None of the above said technology suggests an easy and simple way of implementation of the EGR mechanism which is not bulky or complicated. There is no known art which completely eliminates the need of extra elements which are to be added in the system.
[0006] Furthermore, all the above methods of exhaust gas recirculation require an external tapping of exhaust gas and a flow path for introducing this tapped exhaust gas back to the cylinder of the engine. This further adds to the manufacturing cost and introduces many failure points due to extra mountings added to achieve the objective. Hence, there is a requirement for introducing exhaust gases into engine cylinder to reduce NOx through a process which is simple, eliminates the requirement of extra mounting of external parts without making the system complicated and is cost effective as well.
BRIEF DESCRIPTION OF DRAWINGS
[0007] The detailed description of the present subject matter is described with reference to the accompanying figures. Same numbers are used throughout the drawings to reference like features and components.
[0008] Figure 1 illustrates a right side view of an exemplary two-wheeled vehicle, in accordance with an embodiment of the present subject matter.
[0009] Figure 2 illustrates a plain enlarged view of right side of a cylinder head of the internal combustion engine of the exemplary two-wheeled vehicle in accordance with an embodiment of the present subject matter.
[00010] Figure 3 illustrates a cross sectional view of the right side of the cylinder block of the internal combustion engine in accordance with an embodiment of the present subject matter.
[00011] Figure 4 illustrates a cross sectional view of the cylinder head of the internal combustion engine in accordance with an embodiment of the present subject matter.
[00012] Figure 5 illustrates an enlarged cross sectional view of the cylinder head with respect to an exhaust port and inlet port of the internal combustion engine in accordance with an embodiment of the present subject matter.
[00013] Figure 6 illustrates a perspective view of a plunger disposed in the cylinder head in accordance with an embodiment of the present subject matter.
[00014] Figure 7 illustrates a cross sectional view of the cylinder head along with the operation of a valve mechanism provided in the internal combustion engine, in accordance with an embodiment of the present subject matter.
[00015] Figure 8 illustrates a cross sectional view of the cylinder head along with the operation of the valve mechanism provided in the internal combustion engine, in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION
[00016] Generally, the internal combustion engine is the power unit of the vehicle enabled to provide the required drive. Typically, the internal combustion engine is coupled to the drive wheel, which is generally the rear wheel. Mostly, the internal combustion engine comprises of a cylinder bore where the combustion occurs to provide the needed power for the forward motion of the vehicle. The internal combustion (IC) engine, among other components, comprises of a cylinder on top of which a cylinder head is mounted. The cylinder head is mounted to accommodate and receive the to-and-fro motion of the piston reciprocating from the bottom in an upward direction. 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 rotary motion of the crankshaft which in turn powers the vehicle.
[00017] However, the combustion process of the internal combustion engine leads to generation of exhaust gases. The exhaust gas generated after the combustion is a combination of different gases like N2, CO2, CO, H2O, NO, and NO2 etc. Most of the gases generated like NO, and NO2 (combined called as NOx) are harmful and are considered as major pollutants. An exhaust port is disposed on the cylinder head of internal combustion engine through which the exhaust gases generated leave. The vehicle also comprises of an exhaust pipe connected to the exhaust port, which carries the exhaust from the internal combustion to the muffler region for various other processes. Quite a number of mechanisms and devices are incorporated for treating of exhaust gases. One such element used is the catalytic converter which tries oxidizing the exhaust gases to convert it into harmless gasses. Another such mechanism used is exhaust gas recirculation (EGR) which tries reducing the production of NOx (NO, and NO2) during combustion of air-fuel mixture.
[00018] Moreover, systems used for EGR process enabled to reduce the NOx in the exhaust gases are already known. Some of such known systems are secondary air injection (SAI), optimized catalytic converter for treating exhaust gases coming out of the combustion chamber. The method of injecting secondary air decreases the CO component of the exhaust, but leads to high NOx emission. In one of the other known process EGR works by recirculation a portion of exhaust gasses generated by the internal combustion engine back to its cylinder. The process of introduction of exhaust dilutes the O2 in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures. In yet another known process, spark timing optimization with optimized EGR flow rates is used to reduce NOx while maintaining fuel consumption at a pre-determined level. In one of the other methods, the exhaust which being re-circulated through EGR process is advisable to cool to enhance the performance and reduce the amount of NOx being produced. However, the present known arts generally use an exterior system or a body which is filled with coolant and mounted over the engine to cool the exhaust to be used for EGR. But, such known arts make the whole system bulky, hard to maintain and expensive too. In addition to it, valves are mounted on the internal combustion engine which controls the EGR flow.
[00019] All the above mentioned known mechanisms require an extra mounted element to be added in the system which makes the whole arrangement bulky, complicated and prone to even more failure modes. As explained above, implementation of any known processes, be it SAI, spark timing optimization or optimized catalytic converters either make the system bulky and complicated or increase the probability of greater failure modes. All the above said technologies require loads of maintenance as well. None of the above said technology suggests an easy and simple way of implementation of the EGR mechanism which is not bulky or complicated. There is no known art which completely eliminates the need of extra mounted elements to be added in the system. The above described methods of exhaust gas recirculation require an external tapping of exhaust gas and a flow path for introducing this tapped exhaust gas back to the cylinder of the engine. But, such known arts make the whole system bulky, hard to maintain and expensive too. Furthermore, the extra tapping requires and extra mounting aspect which needs to be added on the internal combustion engine. The aspect of extra tapping comprises with the limited space available for the other existing elements. In addition to it, the mounted tapping leads to noise and vibration problems, and is not stable as well. The probability of breaking and other failure modes when extra tapping is mounted on the internal combustion engine is higher. This further adds to the manufacturing cost and introduces many failure points as well. This increases the number of elements being added to the internal combustion engine to achieve the objective. In furtherance to it, the manufacturing cost is increased and maintenance becomes tedious. The chances and number of failure points are also increased due to extra elements added to achieve the objective. Hence, there is a requirement for introducing exhaust gases into engine cylinder to reduce NOx through a process which is simple, eliminates the requirement of extra mounting of external parts without making the system complicated and is cost effective as well.
[00020] Therefore, an objective of the present subject matter is to reduce the NOx being generated through an EGR mechanism. In addition to it there is a need of a system which is simple, does not requires mounting of elements or tapping to be added on top making the system bulky and is cost effective as well. According to one aspect of the invention a passage is to be created which allows the passage of exhaust from the exhaust port to the inlet port. This introduction of exhaust in the inlet port is to be done in a controlled manner and through a passage created in the internal combustion engine itself. The flow through the passage is controlled by a valve mechanism disposed within the cylinder head and operated through the engine speed. Due to introduction of EGR into the cylinder during an intake cycle, the attainment of high temperature is controlled and therefore NOx formation is reduced. Thus, the present subject matter provides an EGR mechanism which is simple, cost effective and does not requires extra mountings on the internal combustion engine. In furtherance to it, the present subject matter eliminates the need of any external tapping on the internal combustion engine, reducing the chances of failures and making the system cost effective as well.
[00021] In an embodiment, an internal combustion engine comprises of a cylinder block to accommodate the reciprocatory of the piston. The internal combustion (IC) engine, among other components, comprises of a cylinder head mounted over the cylinder block. The cylinder head is mounted to accommodate and receive the to-and-fro motion of the piston reciprocating from the bottom in an upward direction. The cylinder head allows the combustion to occur, hence is also termed as combustion chamber. 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 rotary motion of the crankshaft which in turn powers the vehicle.
[00022] In an embodiment, the internal combustion engine comprises of an inlet port and an exhaust port formed in the cylinder head through which air fuel mixture is sent in and after combustion the exhaust is sent out. The internal combustion engine comprises of an inlet valve and exhaust valve to control the opening and closing of the passage of the exhaust port and inlet port. The opening and closing of the exhaust valve and the inlet valve is based on the kind of stroke occurring in the engine, whether it is an intake stroke, compression stoke or a power stroke. In an embodiment, the exhaust vale and inlet valve are actuated by a rocker arm. The actuation of the rocker arms is controlled by lobes mounted over a camshaft which is driven by the crankshaft through a timing chain, and driving and driven sprockets. Such engines are provided with one spark plug which forms an integral part of the internal combustion engine and develops a spark. The spark developed in the combustion chamber of the internal combustion engine ignites the air-fuel mixture and develops the required power.
[00023] The air fuel mixture commonly referred to as 'charge' is in the compressed condition at the near end of the compression stroke. This charge is in swirling and tumbling motion inside the combustion chamber so that when the spark produced by the spark plug ignites the charge, power is developed. Due to the swirling and tumbling motion, the flame inside the combustion chamber propagates in a desired manner and the peak of the developed power occurs at an instant as required by the design. In order to achieve optimum performance, the location of spark plug tip, velocity of the charge, the direction of swirl and tumble are some of the important parameters.
[00024] In an embodiment, the internal combustion engine cycle begins with the intake stroke as the piston is pulled towards the crankshaft. In intake stroke, the inlet valve is open, through which air-fuel mixture is drawn past the valve into the combustion chamber through the inlet port located on top of the combustion chamber. For the intake stroke the exhaust valve is closed and the electrical contact switch is open and the air-fuel mixture is at a relatively low pressure (near atmospheric). At the end of the intake stroke, the piston is located at the before dead centre (BDC) and begins to move back towards the top dead centre (TDC). The cylinder and combustion chamber are full of the low pressure air-fuel mixture and, as the piston begins to move to the TDC, the intake valve closes. The opening and closing of the intake valve relies on the slightly lower pressure within in the cylinder during the intake stroke to overcome the strength of the spring holding the valve shut. Modern internal combustion engines use cams and rocker arms for opening and closing of the exhaust valve and inlet valve, since cams and rocker arms provide better control and timing of the opening and closing of the valves.
[00025] In furtherance to it, next is a compression stroke in which with both the inlet valve and exhaust valve are closed and the cylinder and combustion chamber form a completely closed vessel with the air-fuel mixture inside. As the piston is pushed to the TDC, the volume is reduced and the air-fuel mixture is compressed during the compression stroke. However, no heat is transferred to the air-fuel mixture during the compression stroke. As the volume is decreased because of the piston's motion, the pressure in the gas is increased, as described by the laws of thermodynamics. During the compression stroke, the electrical contact for spark plug is kept open.
[00026] After the compression stroke is done with, a power stroke is introduced, in which the electrical contact is opened. When the volume is the smallest, and the pressure being highest, the contact is closed, and a current of electricity flows through the spark plug. The sudden closing of the contact produces a spark in the combustion chamber which ignites the air-fuel mixture. Rapid combustion of the fuel releases heat, and produces exhaust gases in the combustion chamber. Because the inlet and exhaust valves are closed, the combustion of the fuel takes place in a totally enclosed (and nearly constant volume) vessel. The combustion increases the temperature of the exhaust gases, any residual air in the combustion chamber, and the combustion chamber itself. From the ideal gas law, the increased temperature of the gases also produces an increased pressure in the combustion chamber. The high pressure of the gases acting on the face of the piston causes the piston to move to the BDC which initiates the power stroke. Unlike the compression stroke, the hot gas does work on the piston during the power stroke. The force on the piston is transmitted by the piston rod to the crankshaft, where the linear motion of the piston is converted to rotational motion of the crankshaft. The motion of the piston is then used to turn a crankshaft in cylinder's compression stroke. Having produced the igniting spark, the electrical contact remains closed. During the power stroke, the volume occupied by the gases is increased because of the piston motion and no heat is transferred to the air-fuel mixture. As the volume is increased because of the piston's motion, the pressure and temperature of the gas are decreased.
[00027] Lastly, is an exhaust stroke which comes at the end of the power stroke when the piston is located at a far BDC. The exhaust valve is then opened by the cam pushing on the rocker arm to begin the exhaust stroke. The purpose of the exhaust stroke is to clear the cylinder of the spent exhaust in preparation for another intake/ignition cycle. As the exhaust stroke begins, the cylinder and combustion chamber are full of exhaust products at low pressure. Because the exhaust valve is open, the exhaust gas is pushed past the valve and exits the engine. The inlet valve is closed and the electrical contact is open during this movement of the piston.
[00028] Generally, the cylinder block accommodates the piston with its reciprocatory motion, such that the motion of the piston is converted into rotational motion of the crankshaft. In an embodiment, the cylinder head is disposed above the cylinder block to allow the combustion to happen. As explained above, the cylinder head also comprises of exhaust port and inlet port through which the exhaust leaves and the air-fuel mixture enters into the internal combustion engine. The cylinder head is provided with exhaust valve and inlet valves which control the opening and closing of the exhaust port and inlet port. In furtherance to it, the cylinder head also comprises of a camshaft, wherein the crankshaft and camshaft extend parallel to each other, and the axis of rotation for the camshaft and crankshaft is similar to each other. The camshaft comprises of an exhaust lobe and inlet lobe disposed on it, which help in the opening and closing of the exhaust valve and the inlet valve. A rocker arm and roller arrangement is provided for the opening and closing of the exhaust valve and inlet valve, wherein the rocker and roller arm is in connection with the exhaust lobe and the inlet lobe, such that the rotation of the lobes helps in rotation of the roller and movement of the rocker arm resulting in opening and closing of the valves.
[00029] In an embodiment, the cylinder head also comprises of an internal passage through which exhaust from the exhaust port travels to enter the inlet port. The internal passage describes here is used for EGR mechanism, hence, hereinafter for the purposes of this application it is referred as an EGR passage. The EGR passage is formed in the cylinder head of the internal combustion engine and helps to achieve the objective of EGR by introducing some amount of exhaust into the inlet port. However, the introduction of exhaust through the EGR passage is done in a controlled manner, varying with respect to the engine speed. In an embodiment, a first connecting passage connects the exhaust port to the EGR passage allowing the exhaust to travel from the exhaust port to the EGR passage. The inlet port is connected to the EGR passage through a second connecting passage, which allows the exhaust coming form the EGR passage to enter the inlet port. However, as per the present subject matter, a valve mechanism is also introduced in the cylinder head of the internal combustion engine to control the amount of exhaust which travels from the exhaust port to the inlet port through the EGR passage. As per the present subject matter, the valve mechanism is being operated by the engine speed. In an embodiment, the cylinder head comprises of a cooling jacket which is provided to control the temperature. The EGR passage is surrounded by the cooling jacket which cools the exhaust traveling from the exhaust port to the inlet port.
[00030] In an embodiment, the valve mechanism described above comprises of a plunge which is operated through a throttle cable, being pushed and pulled against a spring provided in the system. A valve case is provided on the internal combustion engine to hold the spring and plunger, wherein the valve case is disposed on a side of the internal combustion engine near the exhaust port. The spring is rested in the valve case with the plunger placed on it being connected to the throttle cable. The plunger disposed on the spring passes through an opening provided in the EGR passage to rest in a cut portion provided in the casting of the cylinder head. The opening and cut portion provided have a width similar to that of the plunger, such that it is only provided with a minimum clearance for operation. In an embodiment, the plunger passes though an opening provided in the EGR passage to block the movement of exhaust from the exhaust port to the inlet port, wherein the plunger passes through the opening and rests in the cut portion provided in line with the opening in the cylinder head. The plunger rests in the same state explained above until and unless on being operated by the throttle cable. On opening of a throttle valve, the throttle cable pulls the plunger against the spring on which it is disposed. As the plunger is pulled in an outward direction by the throttle cable, it comes out from the cut portion and slowly a clearance is also created in the EGR passage for movement of the exhaust from the exhaust port to the inlet port. However, as soon as the throttle valve closes, the plunger is pushed back by the spring to its original position of resting in the cut portion provided in the cylinder head and blocks the EGR passage by passing through the opening provided in it.
[00031] In an embodiment, the plunger used for blocking the EGR passage is a substantial dumbbell shaped element comprising of a full throttle inhibiting portion, an EGR allowing portion and a zero throttle inhibiting portion. The zero throttle inhibiting portion is formed at a rear portion of the plunger to which the throttle cable is connected, wherein the width of the zero throttle inhibiting portion allows a minimal operating clearance with respect to the opening and cut portion provided in the cylinder head. The EGR allowing portion is formed above the zero throttle inhibiting portion at a central portion of the plunger, wherein the EGR allowing portion has the maximum clearance with respect to the opening. In furtherance to it, the full throttle inhibiting portion is formed above the EGR allowing portion at a front portion of the plunger, wherein the full throttle inhibiting portion also has a width almost similar to that of the opening and cut portion with a minimal operating clearance with respect to it. In an embodiment, when the throttle valve is closed the throttle cable is not action and there is no pulling force experienced by the plunger. This is the resting condition for the plunger when it rests in the cut portion provided in the cylinder head, while passing through and blocking the opening provided in the EGR passage. In such a state, the zero throttle inhibiting portion blocks the opening provided in the EGR not allowing exhaust to pass through, since its width is almost same as that of the opening and has a minimal operating clearance. In an embodiment, when the throttle valve is partially opened the plunger experiences a pull from the throttle cable resulting in movement of the plunge in an outward direction from the cut. In such a condition the EGR allowing portion comes in and blocks the opening provided in the EGR passage, allowing the exhaust to pass around it since it has maximum clearance provided. In an embodiment, when the throttle valve is completely open, the throttle cable pulls the plunger with the maximum force. In such a condition, the full throttle inhibiting portion comes in and blocks the opening provided in the EGR passage, again not allowing the exhaust to flow since, width of the full throttle inhibiting portion has a same width as that of the opening with a minimal operating clearance.
[00032] In an embodiment, when the throttle valve is again closed and the throttle cable is in relaxed condition, there is no pulling force experienced by the plunger. In such a condition, the plunger again goes back to rest in the cut portion provided in the casting of the cylinder head, and the zero throttle inhibiting portion blocks the opening provide in the EGR passage, not allowing exhaust to flow because of the minimal operating clearance it has with respect to the opening. Thus, the working of the valve mechanism is controlled by the engine speed, based on the opening and closing of the throttle valve and being operated by the throttle cable.
[00033] Hence, according to the present invention, an EGR passage is created in the internal combustion engine to allow the exhaust from the exhaust port to enter in the inlet port. According to an embodiment, of the present subject matter, the exhaust which travels from the exhaust port to the inlet port through EGR passage is operated in a controlled fashion. A valve mechanism which is operated through engine speed controls the amount of exhaust which would enter the inlet port. The present subject matter does not requires any additional extra elements or tapping to be done in the internal combustion engine as compares to the other known arts. In furtherance to it, the present subject matter does not make the internal combustion engine bulky or complex. Thus, the present subject matter is simple, cost effective and nor does increases the probability of failure modes and extra maintenance.
[00034] The aforesaid and other advantages of the present subject matter would be described in greater detail in conjunction with the figures in the following description.
[00035] Arrows provided in the top right corner of each figure depicts direction with respect to the vehicle, wherein an arrow F denotes front direction, an arrow R indicated R direction, an arrow Up denotes upward direction, an arrow Dw denoted downward direction, an arrow Rh denotes right side, an arrow Lh denoted left side, as and where applicable.
[00036] Fig. 1 illustrates a right side view of an exemplary two-wheeled vehicle (10), in accordance with an embodiment of the present subject matter. However, the present subject matter can be used for multi-wheeled vehicles comprising of two-heeled and three-wheeled vehicles. Henceforth, for the purposes of this application the multi-wheeled vehicle may be referred as a two-wheeled vehicle or a vehicle. The vehicle (10) includes a frame assembly (not shown) that extends from a head tube (not shown), which is disposed in the front portion of the vehicle (10). The frame assembly includes a mainframe (not shown) comprising a main tube extending rearward from a rear portion of the head tube and a down tube (not shown) that extends rearwardly downward from the head tube. The frame assembly may further comprise a sub-frame formed by a pair of rear tubes (not shown) that extend obliquely rearward from the main frame. An internal combustion engine (5) is supported by the main frame of the frame assembly. The internal combustion engine (5) acts as the power unit of the vehicle (10), wherein the power unit may also include a traction/electrical motor (not shown). A front portion of a swing arm assembly is swingably connected to the main frame of the frame assembly and rear portion of the swing arm assembly rotatably supports a rear wheel (3). The rear wheel (3) is functionally coupled to the internal combustion engine (5) through a transmission system. A rear fender (4) disposed upwardly of the rear wheel (3) covers at least a portion of the rear wheel (3). Further, the swing arm assembly is coupled to the frame assembly through one or more rear suspension(s). A pair of front forks (7) supports a front wheel (6) and is steerably supported by the head pipe. A handlebar assembly (1) is connected to an upper portion of the pair of front fork (7). Further, a front fender assembly (11) covers at least a portion of the front wheel (6) and the front fender assembly (11) is mounted to the front forks (7).
[00037] A fuel tank (9) is mounted to the main tube of the frame assembly and disposed rearwardly of the handlebar assembly (1). A seat assembly (2) is disposed rearwardly of the fuel tank assembly (1) and supported by the pair of rear tubes. Further, the vehicle (10) comprises a visor assembly (12) that is disposed forwardly over the headlamp (8). A tail cover assembly (13) is disposed rearwardly of the side panel assembly (not shown) and extends along the pair of rear tubes thereby covering at least a portion of the pair of rear tubes. The tail cover assembly (13) extends towards a rear portion of the frame assembly and the tail cover assembly (13) is adapted to accommodate a pillion handle (14) attached to its side.
[00038] Figure 2 illustrates a plain enlarged view of right side of a cylinder block (25) of the internal combustion engine (5) of the exemplary two-wheeled vehicle (10) in accordance with an embodiment of the present subject matter. Generally, the internal combustion engine (5) comprises of a cylinder block (25) which accommodates a reciprocating piston (shown in Fig. 3) and a cylinder head (24) where the combustion of the air-fuel mixture occurs. In furtherance to it, a throttle valve (26) is provided in the throttle body which supplies the required air content to the internal combustion engine (5). The cylinder head (24) comprises of an inlet port (21) through which the air-fuel mixture enters the internal combustion engine (5) and an exhaust port (22) through which the exhaust generated after combustion leaves the internal combustion engine (5). An inlet pipe (23) connects the throttle body and the inlet port (21) to form the intake system to supply the air-fuel mixture into the internal combustion engine (5). The exhaust generated after combustion of the air-fuel mixture leaves the internal combustion engine (5) through an exhaust pipe connected to the exhaust port (22) disposed on the cylinder head (24).
[00039] Figure 3 illustrates a cross sectional view of the right side of the cylinder block (25) of the internal combustion engine (5) in accordance with an embodiment of the present subject matter. In an embodiment, the cylinder block (25) accommodates the piston (31) with its reciprocatory motion, such that the motion of the piston (31) is converted into rotational motion of the crankshaft (32). In an embodiment, the cylinder head (24) is disposed above the cylinder block (25) to allow the combustion to happen. As explained above, the cylinder block (25) also comprises of exhaust port (22) and inlet port (21) through which the exhaust leaves and the air-fuel mixture enters into the internal combustion engine (5). The cylinder head (24) is provided with an exhaust valve (33) and inlet valve (34) which controls the opening and closing of the exhaust port (22) and inlet port (21). In furtherance to it, the cylinder head (24) also comprises of a camshaft (35), wherein the crankshaft (32) and camshaft (35) extend parallel to each other, and the axis of rotation for the camshaft (35) and crankshaft (32) is similar to each other. The camshaft (35) comprises of an exhaust lobe (shown in Fig. 4) and inlet lobe (shown in Fig. 4) disposed on it, which help in the opening and closing of the exhaust valve (33) and the inlet valve (34). A rocker arm and roller arrangement (shown in Fig. 4) is provided for the opening and closing of the exhaust valve (33) and inlet valve (34), wherein the rocker and roller arm is in connection with the exhaust lobe and the inlet lobe, such that the rotation of the lobes helps in rotation of the roller and movement of the rocker arm resulting in opening and closing of the valves (33, 34).
[00040] Figure 4 illustrates a cross sectional view of the cylinder head (24) of the internal combustion engine (5) in accordance with an embodiment of the present subject matter. The camshaft (35) can be seen to be comprising of the exhaust lobe (41) and the inlet lobe (42). An exhaust side roller is in connection (43) with the exhaust lobe (41) and an inlet side roller (44) is in connection with the inlet lobe (42). The exhaust lobe (41) and inlet lobe (42) rotate and move along the axis of the rotation of the camshaft (35). This is in turn results into the rotation of the exhaust side roller (43) and inlet side roller (44), which in turn is connected to an exhaust side arm (45) and an inlet side arm (46). The exhaust side arm (45) and inlet side arm (46) are connected to the exhaust valve (33) and the inlet valve (34), such that with the rotation of the exhaust side roller (43) and inlet side roller (44) the exhaust side arm (45) and inlet side arm (46) also move resulting in movement of the exhaust valve (33) and inlet valve (34). Thus, the movement of the exhaust valve (33) and inlet valve (34) result in opening and closing of the exhaust port (22) and inlet port (21) depending upon the type of stroke the internal combustion engine is going through.
[00041] Figure 5 illustrates an enlarged cross sectional view of the cylinder head (24) with respect to the exhaust port (21) and inlet port (22) of the internal combustion engine (5) of the exemplary two-wheeled (10) vehicle as shown in Fig. 1, in accordance with an embodiment of the present subject matter. In an embodiment, the cylinder head (24) of the internal combustion engine (5) comprises of an internal passage (57) formed in it. The internal passage (57) is used for EGR flow, and hereinafter for the purposes of this application is refereed as EGR passage (57). The EGR passage (57) carries exhaust from the exhaust port (22) to the inlet port (21). In an embodiment, a first connecting passage (53) connects the exhaust port (22) to the EGR passage (57), and a second connecting passage (56) which connects the inlet port (21) to the EGR passage (57). All of the exhaust generated after combustion does not completely leaves through the exhaust port (22), and some minimal amount of the exhaust is allowed to enter the EGR passage (57) through the first connecting passage (53). After traveling through the EGR passage (57), the exhaust enters the inlet port (21) through the second connecting passage (56). The exhaust only travels from the exhaust port (22) to the inlet port (21) through the EGR passage (57) because of the pressure difference between them, and the direction of travel cannot be reversed. However, the whole process of sending exhaust from the exhaust port (22) to the inlet port (21) through the EGR passage (57) is being conducted in a controlled manner based on the engine speed. In an embodiment, a valve case (54) is disposed on one side of the internal combustion (5) engine below the exhaust port (22). A spring (59) is disposed in the valve case (54) on which a plunger (58) is disposed. The plunger is connected to a throttle cable (55), used for pulling the plunger (58) against the spring (59). In an embodiment, the EGR passage (57) comprises of an opening (52) through which the plunger passes and enters a cut portion (50) provided in the casting of the cylinder head (24) for the plunger (58) to rest when it is not being operated. The plunger (58) while passing through the opening (52) provided in the EGR passage (57) actually blocks the path between the first connecting passage (53) and the EGR passage (57), not allowing exhaust to enter into the inlet port (21). In an embodiment, the cylinder head (24) also comprises of a cooling jacket (51) through which coolant is passed to maintain the engine temperature. The EGR passage (57) formed in the cylinder head (24) is surrounded by the cooling jacket (51) such that the exhaust flowing from the exhaust port (22) is cooled before entering the inlet port (21). The cooling of the exhaust through the cooling jacket (51) enhances the efficiency of the system by reducing the amount of NOx which is generated. The cooling jacket (51) receives cooling medium used for cooling the cylinder head (24) and parts thereof. The EGR passage (57) being within the cylinder head, effective utilises the same cooling medium to cool the exhaust gases and no separate cooling system for EGR is required.
[00042] Figure 6 illustrates a perspective view of the plunger (58) used for blocking the EGR passage (57) formed in the cylinder head (24), in accordance with an embodiment of the present subject matter. In an embodiment, the plunger (58) is a substantial dumbbell shaped structure. The plunger (58) comprises of a zero throttle inhibiting portion (65), an EGR allowing portion (63) and a full throttle inhibiting portion (61). In an embodiment, the zero throttle inhibiting portion (65) is formed in the rear portion of the plunger (58) to which the throttle cable (55) is connected. The zero throttle inhibiting portion (65) has a width almost same as that of the opening (52) and the cut portion (50), such that the zero throttle inhibiting portion (65) has a minimal operation clearance with respect to it. In an embodiment, the plunger further comprises of an EGR allowing portion (63) formed at a central region above the zero throttle inhibiting portion (65). The EGR allowing portion (63) has the maximum clearance with respect to the opening (52) and cut portion (50) provided. In an embodiment, the full throttle inhibiting portion (61) is formed at a front portion of the plunger (58) above the EGR allowing portion (63). The width of the full throttle inhibiting portion (61) is almost same as that of the opening (52) and cut portion (50), providing a minimal operating clearance to it with respect to the opening (52) and cut section provided (50).
[00043] Figure 7 illustrates a cross sectional view of the cylinder head (24) along with the operation of a valve mechanism (72) provided in the internal combustion engine (5), in accordance with an embodiment of the present subject matter. In an embodiment, a valve mechanism (72) is provided in the cylinder head (24) of the internal combustion engine (5) to control the flow of exhaust from the exhaust port (22) to the inlet port (21) through the EGR passage (57). The valve mechanism (72) comprises of plunger (58), spring (59) and the throttle cable (55) used to pull the plunger (58). In an embodiment, the plunger (58) does not experiences any pull from the throttle cable (55) when the throttle valve is closed. In such a state, the plunger (58) passes through the opening (52) to get disposed in the cut section (50), and the zero throttle inhibition portion (65) blocks the opening (52) provided in the EGR passage (57) not allowing exhaust to flow from the exhaust port (22) to the inlet port (21). None of the exhaust flows around the minimal operating clearance provided for the zero throttle inhibiting portion (65). However, as the figure illustrates, in case when the throttle valve (26) is partially open, there is a certain pulling force experienced by the plunger (58) through the throttle cable (55). In such a state, the plunger (58) is pulled in an outward direction form the cut portion (50) such that the EGR allowing portion (63) blocks the opening (52) provided in the EGR passage (57). The EGR allowing portion (63) allows exhaust to flow from the exhaust valve (22) to the internal valve (21), since it has the maximum clearance with respect to the opening (52) and cut portion (50) provided. In an embodiment, the EGR passage (57) is surrounded by the cooling jacket (51) which cools the exhaust flowing from the exhaust port (22) to the inlet port (21) throughout the whole working of valve mechanism (72).
[00044] Figure 8 illustrates a cross sectional view of the cylinder head (24) along with the operation of the valve mechanism (72) provided in the internal combustion engine (5), in accordance with an embodiment of the present subject matter. In an embodiment, the plunger (58) experiences a pull from the throttle cable (55) with a maximum force when the throttle valve (26) is completely open. In such a state, the plunger (58) is pulled out from the cut portion (50) such that the full throttle inhibition portion (61) blocks the opening (52) of the EGR passage (57) not allowing exhaust to flow. The full throttle inhibiting portion (61) has a minimal operating clearance, such that it does not allows the exhaust to flow around it. In an embodiment, when the throttle valve (26) closes and the throttle cable (55) is released the plunger (58) comes back to its original state in the resting state in the cut portion (50). In such a state, the zero throttle inhibiting portion (65) comes back to block the opening (52) provided in the EGR passage (57) not allowing exhaust to flow form the exhaust port (22) to the inlet port (21) through the EGR passage (57). In furtherance to it, the coolant jacket (51) cools the exhaust flowing through the EGR passage (57) at all the times irrespective of the position of the plunger (58).
[00045] Thus, the present subject matter provides an internal combustion engine (5) with an EGR passage (57) provided inside the cylinder head (24), allowing a smooth flow of exhaust from the exhaust port (22) to the inlet port (21). The flow of exhaust is controlled by a valve mechanism (72) controlled by a throttle cable (55). In furtherance to it, the EGR passage (57) is surrounded by a cooling jacket (51) which cools the exhaust flowing from the exhaust port (22) to the inlet port (21) at all the times. Such an arrangement makes the whole system simpler and cost effective. It also reduces the number of parts being used, reduces the probability of failure points and improves the maintainability.
[00046] It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein. 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.
,CLAIMS:We claim:
1. An internal combustion engine (5) for a multi-wheeled vehicle (10), comprising:
a cylinder block (25) comprising a cylinder to accommodate a reciprocating piston (31) for combustion of fuel;
a cylinder head (24) disposed over said cylinder block (25) to receive said reciprocation piston (31);
an inlet port (21) formed on said cylinder head (24) to allow entry of air-fuel mixture in said internal combustion engine (5);
an exhaust port (22) formed on said cylinder head (24) to allow exhaust formed after combustion to leave said internal combustion engine (5);
a valve mechanism (72) being operated through engine speed and disposed within said cylinder head (24);
an internal passage (57) formed in said cylinder head (24) to connect said exhaust port (22) and said inlet port (21) enabling a passage for exhaust to flow from said exhaust port (22) to said inlet port (21), wherein flow through said internal passage (57) is controlled through said valve mechanism (71) being operated on engine speed.
2. The internal combustion engine (5) as claimed in claim 1, wherein said exhaust port (22) is connected to said internal passage (57) through a first connecting passage (53) enabling a flow of exhaust thereto, and wherein said inlet port (21) is connected to said internal passage (57) through a second connecting passage (56) enabling flow of exhaust from said internal passage (57) to said internal port (21).
3. The internal combustion engine (5) as claimed in claim 1, wherein said valve mechanism (72) comprises of a spring (59) on which a plunger (58) is disposed being connected to a throttle cable (55), wherein said throttle cable (55) is operated through a throttle valve (26) enabled to regulate flow of air to said cylinder head (24), and wherein said valve mechanism (72) is operated through engine speed by pulling of said plunger (58) through said throttle cable (55) against said spring (59).
4. The internal combustion engine as claimed in claim 1, wherein said internal passage (57) comprises of an opening (52) through which said plunger (58) passes to fit in a cut portion (50) formed in said cylinder head (24) in a same line as that of said opening (52) and block exhaust flow between said exhaust port (22) and said internal passage (57).
5. The internal combustion engine (5) as claimed in claim 1 or claim 4, wherein said plunger (58) is a substantial dumbbell shaped element, with a zero throttle inhibiting portion (65) formed at a rear portion therein comprising of a minimal operating clearance with respect to said opening (52) and said cut portion (50), and being connected to said throttle cable (55).
6. The internal combustion engine (5) as claimed in claim 1 or claim 4, wherein said plunger (58) comprises of an EGR allowing portion (63) formed at a center portion therein comprising of a maximum clearance with respect to said opening (52) and said cut portion (50), and wherein said plunger (58) further comprises of a full throttle inhibiting portion (61) formed at a rear portion therein comprising of a minimal operating clearance with respect to said opening (52) and said cut portion (50).
7. The internal combustion engine (5) as claimed in claim 5, wherein said zero throttle inhibiting portion (65) blocks said opening (52) preventing flow of exhaust when said throttle cable (55) is in a non-operating condition and does not pull said plunger (58).
8. The internal combustion engine (5) as claimed in claim 6, wherein said EGR allowing portion (63) blocks said opening (52) allowing flow of exhaust when said throttle cable (55) pulls said plunger (58) by a partial opening of said throttle valve (26).
9. The internal combustion engine as claimed in claim 6, wherein said full throttle inhibiting portion (61) blocks said opening (52) preventing flow of exhaust when said throttle cable (55) is under maximum operation by a full opening of said throttle valve (26).
10. The internal combustion engine (5) as claimed in claim 1, wherein said internal passage (57) is surrounded by a cooling jacket (51) enabled for cooling of exhaust traveling from said exhaust port (22) to said inlet port (21) through said internal passage (57).