THEREOF

TECHNICAL FIELD

[0001] The present subject matter relates to an internal combustion engine for a motor vehicle and more particularly, relates to an exhaust of the internal combustion engine. BACKGROUND

[0002] Generally, in a motor vehicle, an internal combustion (IC) engine includes an intake system for supplying air-fuel to the IC engine. An exhaust system connects the internal combustion engine to a muffler of the vehicle. Generally, the exhaust gas generated in a combustion chamber of the IC engine is discharged to the atmosphere. In the motor vehicle, an exhaust port of the IC engine is connected to an exhaust pipe of the exhaust system enabling discharge of the exhaust gases to the atmosphere. Generally, the position of the exhaust port is subject to specific orientation of mounting of the engine on to the vehicle which has layout & packaging challenges associated with it. Moreover, to effectively reduce emissions from the exhaust gases that are exiting out of the engine, it is important to position a catalytic converter as close as possible to the exhaust port. However, in most motor vehicles, optimally positioning the catalytic converter also becomes a challenge, which is mainly due to the layout constraint of the motor vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS [0003] The detailed description is described with reference to an embodiment of a saddle type two wheeled motorcycle along with the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.

[0004] Fig. 1 depicts a right-side view of an exemplary two- wheeled vehicle, in accordance with an embodiment of the present subject matter.

[0005] Fig. 2 illustrates a right-side view of an internal combustion engine including its exhaust system, in accordance with the embodiment as depicted in Fig. 1. [0006] Fig. 3 (a) illustrates a right-side view of an internal combustion engine with a partial exploded view of the exhaust system, in accordance with an implementation of the present subject matter.

[0007] Fig. 3 (b) illustrates a schematic sectional view of a portion of an IC engine with an exhaust system, in accordance with one implementation of the present subject matter.

[0008] Fig. 3 (c) illustrates an axial view of a sleeve member, in accordance with one implementation of the present subject matter.

[0009] Fig. 3 (d) illustrates an isometric view of a sleeve member, in accordance with one implementation of the present subject matter.

[00010] Fig. 3 (e) illustrates a schematic sectional view of a sleeve member, in accordance with one implementation of the present subject matter of Fig. 3 (c). [00011] Fig. 3 (f) illustrates a schematic sectional view of a portion of the IC engine and the exhaust system, in accordance with one implementation of the present subject matter.

DETAILED DESCRIPTION

[00012] Generally, in motor vehicles, an internal combustion engine (IC) having four-stroke cycle is popularly used. The four-stroke cycle starts with an intake stroke and ends at an exhaust stroke. Air-fuel mixture is drawn into a combustion chamber during the intake stroke and the air-fuel mixture gets compressed during compression stroke. The air-fuel mixture is combusted thereby resulting in a power stroke. Exhaust gases are transmitted to an exhaust system from a cylinder head of the IC engine in order to be expelled from the cylinder head and then to atmosphere. [00013] The exhaust system includes an exhaust pipe with an upstream end connected to an exhaust port of the cylinder head. A muffler is connected to a downstream end of the exhaust pipe and is either disposed towards at least one lateral side of the motor vehicle or is disposed along a vehicle center. The muffler acts as noise attenuator and may be used for treatment of exhaust gases. The exhaust gases are to be treated before expelling from the exhaust system. Thus, the exhaust system is provided with various types of treatment systems. One such popular exhaust gas treatment system is use of a catalytic converter. The catalytic converter is to be accommodated near to the exhaust port in order to achieve an early light- off the catalytic converter. Early light-off is a critical parameter, as only after the light-off does the catalytic converter start effective & efficient treatment of exhaust gases. Moreover, the treatment of exhaust gases includes treating of harmful gases like hydrocarbons, carbon monoxide etc., which are harmful to the environment. With an early light-off, the catalytic converter starts effective functioning right from starting of the IC engine. Therefore, to attain early light-off, the catalytic converter is disposed close to the exhaust port. However, disposing catalytic converter close to the exhaust port has certain challenges. For example, in a forwardly inclined engines or in vertical type engines, which is a typical orientation in two-or three wheeled and some multi-wheeled vehicles, the exhaust pipe undergoes one or more bends in order to be routed from the cylinder head towards the muffler. One of the bends is in proximity to the exhaust port, which makes it complex for the catalytic converter to be disposed close to the exhaust port as the exhaust pipe is configured keeping the vehicle layout in mind, especially considering rider seating posture. In addition, due to high temperatures that may be generated during combustion process, the catalytic converter may get damaged if it is placed close to the exhaust port leading to poor durability. Further, disposing the catalytic converter immediately after the exhaust port may affect breathability of the IC engine as the flow of the exhaust gases is resisted by the catalytic converter creating back pressure. This may result in poor engine performance and poor fuel-economy due to poor flow of exhaust gases, which may affect subsequent cycles (four-stroke) of the IC engine. Also, the performance drop is significant during higher speeds of the IC engine, which may affect the drivability of the vehicle as the user may be over taking or performing a hill climb, which requires engine to operate at higher speeds. [00014] In the art certain attempts were made to modify the cylinder head design or to modify the exhaust system design in order to address one or more aforementioned and other problems. However, there is always a challenge to harmonize such solutions in order to be implementable in various configurations of the IC engines. As certain earlier attempts to address problem are limited to a certain layout of the exhaust system or to a certain configuration of the cylinder head thereby making it restrictive solution. As the configuration of the cylinder head and exhaust system varies with every motor vehicle. For example, for the various configurations of the IC engines and the vehicle layouts, each of the cylinder head and the exhaust system has to be individually re-designed to cater to that layout and design. This makes the known solutions undesirable, complex as well as expensive due to poor harmonization across various engine and vehicle layouts, which pre dominantly requires study and re-design of each layout involving significant time and cost.

[00015] Thus, there is exists a challenge and a need to provide an internal combustion engine that is having an exhaust system that addresses aforementioned and other short comings in the prior art. At the same time, there is need for achieving an optimal emission control, without affecting the engine torque and power. Further, the solution should be harmoniously applied across various engine platform and vehicle layouts without need for re-design of engine, exhaust system or vehicle layout.

[00016] Hence, the present subject matter provides an internal combustion (IC) engine assembly with an exhaust system thereof that is capable of treating exhaust gases with an early light-off catalyst without the need for disposing the catalytic converter unit near to the exhaust port.

[00017] In one embodiment, the IC engine has at least one cylinder head forming a cylinder head assembly. The at least one cylinder head includes at least one intake port and at least one exhaust port. A combustion chamber is defined by the cylinder head and a cylinder block. The combustion chamber is configured to receive intake charge (air-fuel mixture) from a fuel supply device through said at least one intake port and to expel exhaust gases from the combustion chamber through at least one exhaust port and finally into an exhaust pipe.

[00018] In one embodiment, a sleeve member is disposed at a downstream portion of the at least one exhaust port. In one embodiment, the sleeve member couples with the exhaust pipe that gets assembled to a downstream portion of the exhaust port. The sleeve member is configured to enhance one or more flow parameters of exhaust gases flowing through the sleeve members to improve performance one or more systems of the IC engine.

[00019] In one embodiment, the sleeve member comprises an inner cross-sectional area receding in a downstream direction thereof. The sleeve member can be detachably-attached to the exhaust port. Thus, the sleeve member can be customized according to the configuration of the IC engine. The sleeve member with the receding inner cross-sectional area improves flow rate of exhaust gases flowing through the sleeve member. As a result, the exhaust gases flow over a longer distance within a shorter time and are able to retain desired heat.

[00020] The improved flow rate of the exhaust gases improves breathability of IC engine with reduced back-pressure. The drivability of the motor vehicle is improved due to reduced resistance or back-pressure thereby improving performance especially at higher speeds of IC engine operation.

[00021] In one embodiment, the at least one exhaust port is having an upstream portion adjoining the combustion chamber (through a valve/ valve seat) and the downstream portion is adjoining the sleeve member. The term adjoining is not restrictive herein, and may include configuring of the sleeve member at the downstream portion or immediately adjacent to the downstream portion. Thus, the sleeve member can be configured within existing cylinder head layout without need for re-design of the cylinder head.

[00022] In one embodiment, the downstream portion of the exhaust port is having a first cross-sectional area substantially equal to an upstream cross-sectional area of the sleeve member. This enables a smooth transition between the exhaust port and the sleeve member with minimal disturbance to flow of exhaust gases. Further the receding inner cross-sectional area of the sleeve member is configured to be in a smooth and gradual manner to retain the smooth flow & efficient flow dynamics. The receding cross-sectional area can have an inclined profile, a curved profile, or a combination of both.

[00023] In one embodiment, the exhaust pipe comprises an inlet opening and said inlet opening comprises a second cross-sectional area being substantially larger than a downstream cross-sectional area of sleeve member. Thus, the exhaust gases exiting the relatively smaller downstream cross-sectional area confining the flow of exhaust gases substantially away from the exhaust pipe (surface) thereby reducing convection and conduction. Moreover, the enhanced flow rate enables in retention of direction of flow of exhaust gases towards the center away from the surface. [00024] In one embodiment, the sleeve member is disposed within the downstream potion of the at least one exhaust port and the sleeve member is substantially enclosed in an assembled condition. The sleeve member is configured to have a smaller thickness in order to be configured at the exhaust port. Thus, in one embodiment, the sleeve member can be sandwiched between at least a portion of the at least one exhaust port and an inlet opening of exhaust pipe with ease without the need for any modifications of the layout or design.

[00025] In one embodiment, the exhaust pipe includes a flange member, which is adjustable type, in order to accommodate the variation due to incorporation of the sleeve member. In one embodiment, the exhaust pipe includes an insert member disposed adjoining to the sleeve member. The insert member can be inserted in to at least a portion of the exhaust port to form a tight seal. In one implementation, the sleeve member is sandwiched between the exhaust port and the insert member. Thus, the exhaust pipe is secured to the cylinder head through the flange member forming a tight seal without any leak.

[00026] In one implementation, the sleeve member comprises an inner surface, when a cross-section of the inner surface is considered (section taken diametrically, the inner surface is disposed at a first angle with respect to an imaginary axis of the sleeve member. The first angle is an acute angle and it is configured to converge flow of exhaust gases towards the center thereof.

[00027] In one embodiment, the internal combustion engine with the sleeve member define a confined region extending from the sleeve member till a pre determined distance into the exhaust pipe. The configured region is the aforementioned region within which the exhaust gases flow upon exiting the sleeve member and staying away from the surface of the exhaust pipe.

[00028] In one embodiment, the exhaust pipe retains a first bend for routing the exhaust pipe towards a muffler. A catalytic converter unit is disposed subsequent to the first bend and the catalytic converter unit being disposed at a distance of at least 10 times a diameter of the exhaust port from the exhaust port. Thus, the catalytic converter is disposed at a safe distance from the exhaust port eliminating any burn off and still attaining early light-off due to faster flow of exhaust gases with heat retention. In one embodiment, the catalytic converter unit 206 is disposed at a distance of 10 times a cross-sectional dimensional value of at least one of the exhaust port 304 and the sleeve member 350 as the cross-sectional dimensional value defines volume of exhaust gases exiting therethrough thereby defining the position or distance at which the catalytic converter can be disposed.

[00029] Thus, the present subject matter provides a method of retaining temperature of exhaust gas flowing from an exhaust port to an exhaust pipe for an internal combustion engine. The method comprising steps of a) directing exhaust gas exiting said exhaust port through a sleeve member; b) converging flow of exhaust gases towards a center of said member by configuring an inner cross- sectional area AS in a downstream direction thereof; c) defining a confining region within said exhaust pipe till a pre-determined distance from the exhaust port. [00030] Other features and advantages of the present invention are described in the following explanation of the embodiments. Arrows wherever provided in the top right corner in the drawings depicts direction with respect to the vehicle, wherein an arrow F denotes front direction, an arrow R indicates rear direction, an arrow UP denotes upward direction, an arrow DW denotes downward direction, an arrow RH denotes right side, and an arrow LH denotes left side.

[00031] Fig. 1 illustrates an exemplary motor vehicle having an IC engine 101 whose piston axis is substantially vertically disposed. In one embodiment, the IC engine 101 is a single-cylinder type IC engine. The motor vehicle comprises a front wheel 110, a rear wheel 103, a frame assembly 102 (also shown schematically), a fuel tank 121 and seat 106. The frame assembly 102 includes a head pipe 111, a main tube 112, a down tube (not shown), and one or more seat rails (not shown) extending rearward from the main tube 112. The head pipe 111 supports a steering shaft (not shown) and two telescopic front suspensions 114 (only one visible) are attached to the steering shaft through a lower bracket (not shown). The front suspensions 114 supports the front wheel 110. The upper portion of the front wheel 110 is covered by a front fender 115 mounted to the lower portion of the telescopic front suspension 114 at the end of the steering shaft. A handlebar 108 is fixed to upper bracket (not shown) and can rotate to both directions for maneuvering the motor vehicle 100. A head light 109, a visor guard (not shown) and instrument cluster not shown is arranged on an upper portion of the head pipe 111. The down tube may be located in front of the IC engine 101 and extends slantingly downward from head pipe 111. The main tube 112 is located above the IC engine 101 and extends rearward from head pipe 111. The IC engine 101 is mounted at the front by the down tube and rear of the IC engine 101 at the rear portion is connected to the main tube 112.

[00032] The fuel tank 121 is mounted on the horizontal portion of the main tube 112. Seat rails are joined to main tube and extend rearward to support the seat 106. A rear swing arm 118 is connected to the frame assembly 102 to swing vertically, and a rear wheel 103 is connected to rear end of the rear swing arm 118. Generally, the rear swing arm 118 is supported by a mono rear suspension 117 (as illustrated in the present embodiment) or two suspensions on either side of the motor vehicle which is a two-wheeled type. A tail light unit (not shown) is disposed at the end of the motor vehicle at the rear of the seat 106. A grab rail 105 is also provided on the rear of the seat rails. The rear wheel 103 arranged below the seat 106 and rotates by the driving force of the IC engine 101 transmitted through a chain drive 116 from the IC engine 101. A rear fender 127 is disposed above the rear wheel 103. Further, an electric motor may be provided to assist the IC engine 101 or independently drive the motor vehicle 100.

[00033] Fig. 2 illustrates a right-side view of an internal combustion engine 101 including its exhaust system, in accordance with the embodiment as depicted in Fig. 1. In an embodiment, the internal combustion engine 101 includes a cylinder head assembly 210 having a cylinder head 203 and a cylinder head cover 202 mounted atop the cylinder head 203. In an embodiment, the internal combustion engine 101 is a single cylinder engine. More particularly, in one embodiment, the internal combustion engine 101 is a four-stroke internal combustion engine 101. In other alternative embodiment, the internal combustion engine 101 can include more than one cylinder head, say a plurality of cylinders. In an embodiment, the cylinder head 203 of the present subject matter includes one or more ports (not shown in this figure). For example, an exhaust port (not seen in this figure) of the internal combustion engine 101 enables exiting/expelling out the exhaust gases arising out of the combustion of the air-fuel mixture that occurs inside the combustion chamber (not shown) of the internal combustion engine 101. The gases exiting from the exhaust port are transported through an exhaust pipe 200 of the exhaust system of the internal combustion engine 101. In an embodiment, the exhaust pipe 200 includes an inlet opening 201 (shown in Fig. 3) which is connected to the exhaust port (not seen in this figure) of the internal combustion engine 101 for enabling smooth travel of the exiting exhaust gases. The exhaust pipe 200 is connected to the cylinder head through a flange member 321 and an insert member 320 (shown in Fig 3) is a portion of the inlet opening 201 that gets inserted into the cylinder head 203. In on implementation, the flange member 321, the insert member 320, and the sleeve member 350 are integrally formed as a separate unit or along with exhaust pipe 200 in order to enable ease of assembly and avoid missing of parts during servicing or the like.

[00034] In one embodiment, the cylinder head 203 of the internal combustion engine 101 is mounted atop a cylinder block 204. The cylinder head 203 and the cylinder block 204 define a combustion chamber (not shown) and a piston (not shown) is slidable within the combustion chamber resulting in the four-strokes. In an embodiment, the exhaust pipe 200 of the present subject matter includes a first bend 208 adjacent to the inlet opening 201 and a second bend 209 farther from the first bend 208. In an additional embodiment, A protective cover 215 is provided to cover at least a portion of the exhaust pipe 200 in order to protect the exhaust pipe 200 and to keep user feet away from the exhaust pipe 200. In an embodiment, the engine 101 includes at least one spark plug (not shown). In an embodiment, the vehicle 100 is a saddle -ride type vehicle. In another embodiment, the vehicle 100 is a step-through type vehicle. A distance between the first bend 208 and the second bend 209 depends on one or more parameters including a diameter of wheel(s), wheel base between the wheels, ground clearance of the second bend from a road / ground surface etc.

[00035] In an embodiment, the exhaust pipe 200 includes at least one catalytic converter unit 206 optimally disposed from the exhaust port of the cylinder head 203. In one embodiment, the catalytic converter unit 206 is disposed between the first bend 208 and the second bend 209 of the exhaust pipe 200. In an embodiment, the at least one catalytic converter unit 206 is a pre-catalytic converter or an auxiliary catalytic converter, which is provided upstream of a main catalytic converter (not shown) in the exhaust system of the present subject matter. In an alternative embodiment, the main catalytic converter (not shown) is disposed within the muffler 130 of the exhaust system of the present subject matter. In an embodiment, closer the catalytic converter unit 206 to the exhaust port, higher is the efficiency & effectiveness of the catalytic converter unit 206. In an embodiment, an oxygen sensor (not shown) is disposed substantially closer and upstream to the catalytic converter unit 206. For example, in one embodiment, the oxygen sensor is disposed at a distance of about 15 mm to 20 mm upstream of the catalytic converter unit 206.

[00036] Fig. 3 (a) illustrates a right-side view of an internal combustion engine with a partial exploded view of the exhaust system, in accordance with an implementation of the present subject matter. Fig. 3 (b) depicts a schematic sectional view of a portion of the internal combustion engine and the exhaust system, in accordance with an embodiment of the present subject matter. In an embodiment, the cylinder head assembly 210 of the present subject matter has at least one intake port 301 that allows entry of air-fuel mixture into the combustion chamber (not shown). In an embodiment, the intake port 301 is seated on an intake valve seat (not shown) at a juncture where an intake valve (not shown) is disposed at an intake valve disposition opening (not shown) on the cylinder head assembly 210. In an embodiment, the cylinder head assembly 210 includes at least one exhaust port 304 disposed on the other side of the intake port 301. In the depicted embodiment, the intake port 301 is disposed on rearward facing side of the cylinder head 203 and the exhaust port 304 is disposed on a front facing side of the cylinder head 203. In other implementations, the exhaust port 304 can be disposed on a rear facing side or a downward facing side of the cylinder head and the intake port is disposed substantially opposite to the exhaust port.

[00037] An air-fuel supply device 220 is connected to intake port 301 for regulated supply of air and fuel. The air-fuel supply device can be a carburetor, a combination of throttle body and fuel-injector, an electronic carburetor or the like. In an alternative embodiment, the cylinder head assembly 210 can include more than one exhaust port 304.

[00038] In an embodiment, the exhaust port 304 extends between a seat of an exhaust valve seat (not shown) and an exit portion thereof. A portion of the exhaust port 304 that is near the exhaust valve seat is an upstream portion 310 and a portion substantially away from the exhaust valve seat is downstream portion 307. In one embodiment, a sleeve member 350, which is configured to enhance one or more flow parameters of exhaust gases flowing therethrough, is disposed at the downstream portion 307 of the exhaust port 304. The exhaust gas / exhaust gases flow through the sleeve member 350 and then to the exhaust pipe 200. In one embodiment, the sleeve member 350 is detachably disposed at the downstream portion 307 of the exhaust port 304. In one embodiment, the sleeve member 350 couples with the exhaust pipe 200. The sleeve member 350 is configured to be detachably-attached to the exhaust port 304 by at least one of a press-fit, a fastening means, or through any other known means in the art. The sleeve member 350 can be provided in any cylinder head configuration by simply modifying the geometry of the sleeve member 350 thereby avoiding the need for modification of the cylinder head or exhaust system layout. Thus, the present subject matter acts as a harmonious solution that can be implemented in different IC engine platforms as well as in different motor vehicle layouts.

[00039] In one embodiment, the sleeve member 350 comprises an inner cross- sectional area AS receding in a downstream direction thereof. The downstream direction is the direction of flow of the exhaust gases through the sleeve member 350. In one embodiment, the sleeve member 350 increases the flow rate due to venturi effect created by the receding inner cross-sectional area AS and is capable of directing the exhaust gases in a pre-determined direction in the exhaust pipe 200 In one embodiment, the sleeve member 350 provides a smooth or gradually receding inner cross-sectional area AS thereby minimizing any disturbed flow of the exhaust gases.

[00040] In one embodiment, the exhaust gases exiting the sleeve member 350 do not come in contact with the exhaust pipe 200 till a predetermined distance, thereby ensuring that there are no convection/conduction-based heat losses of the exhaust gases, thereby enhancing the retention duration of the heat till the exhaust gases reach the catalytic converter unit 206 and in lesser time compared to conventional IC engines. In the depicted embodiment, due to the receding inner cross-sectional area AS, a confined region 360 is defined within the exhaust pipe 200, especially near the inlet opening 201. The exhaust gases exiting the sleeve member 350 are confined with the fed region 360 with minimal contact with the exhaust pipe 200 till a pre-determined distance. Thus, the gases that exit the sleeve member 350, due to the venturi effect, flow substantially with the region 360. Thus, the exhaust gases exiting the relatively smaller downstream cross-sectional area of the sleeve member 350 are confined within the confined region 360 till at least a pre-determined distance from the exhaust port 304. The exhaust gases flowing from the exhaust port 304 and through the sleeve member 350 are thereby kept away from the exhaust pipe 200 (inner surface) reducing convection and conduction of heat from the exhaust gases. Further, the enhanced flow rate enables in retention of direction of flow of exhaust gases towards the center away from the surface whereby the exhaust gases reach the catalytic converter unit 206 in shorter duration resulting in early light-off. The sleeve member 350 configured to enhance one or more flow parameters like flow rate, direction of flow etc. improves scavenging on exhaust gases and any particulate matter from the combustion chamber due to venturi effect and in treatment of exhaust gases due to early light-off of the catalytic converter unit 206

[00041] Due to improved flow rate and the heat retention, the exhaust gases reaching the catalytic converter unit 206 retain heat enabling early light-off due to heat retention. In one implementation, the sleeve member 350 is configured so that the catalytic converter unit 206 can be disposed at a distance of at least 10 times a diameter of the exhaust port 304. In an alternate implementation, the sleeve member 350 is configured so that the catalytic converter unit 206 can be disposed at a distance of at least 10 times a diameter of the sleeve member 350. In the depicted embodiment, the catalytic converter unit 206 is comfortably disposed after the first bend 208 thereby maintaining the bends in the exhaust pipe 200 layout without the need for modification. In one embodiment, an average diameter of the exhaust port is considered and in other embodiment at least one of a maximum or a minimum cross-sectional dimensional value of the exhaust port is considered. In one embodiment, an average inner diameter of the sleeve member is considered and in other embodiment at least one of a maximum or a minimum inner cross-sectional dimensional value of the sleeve member is considered.

[00042] Figs. 3 (c) - 3 (e) depicts various views of the sleeve member, in accordance with an embodiment of the present subject matter. The sleeve member 350 comprises a wider upstream opening and a relatively narrower downstream opening. An inner surface 351 is configured to be receding in a first direction, which is a downstream direction. Further, an outer surface 352 is configured to be accommodated at the downstream portion 307 of the exhaust port 304. In the depicted embodiment, the exhaust port 304 comprises a substantially cylindrical profile and the outer surface 352 is provided with a circular profile in order to be disposed at the downstream portion 307. The inner surface 351 forms the smooth or gradually receding inner cross-sectional area AS. In the depicted embodiment, the inner surface 351 with the receding inner cross-sectional area forms an inclined profile, disposed at a first angle a with respect to an axis of the sleeve member 350. The first angle a is an acute angle which is configured based on a diameter of the sleeve member 350. In one implementation, the first angle a is a range of 30 to 40 degrees for an inner diameter of about 20 to 30 millimeters. The inner profile may include a smooth curved profile, a combination of curved and inclined, or any other known geometric profile.

[00043] Fig. 3 (f) depicts a schematic enlarged sectional view of a portion of the IC engine and the exhaust system, in accordance with an embodiment of the present subject matter. In one embodiment, the downstream portion 307 is adjoining said sleeve member 350 and the downstream portion 307 of the exhaust port 304 is provided with a first cross-sectional area A1 configured to be substantially equal to an upstream cross-sectional area ASU of the sleeve member 350. Thus, the exhaust gases enter the sleeve member 350 with negligible distortion. In one embodiment, the exhaust pipe 200 comprising of the inlet opening 201 comprises a second cross- sectional area A2 being substantially larger than a downstream cross-sectional area ASD of the sleeve member 350. Even a second cross-sectional area A2’ of the exhaust pipe 200, which is taken away or downstream from the inlet opening 201, is larger than the downstream cross-sectional area ASD of the sleeve member 350. [00044] Further, the sleeve member 350 ensures the catalytic converter unit 206 can be disposed at substantial distance from the exhaust port 304. As the flow rate of exhaust gases exiting the sleeve member 350 is increased, the exhaust gases are capable of retaining heat for a longer distance within the exhaust pipe 200. Thus, the catalytic converter unit 206 can be disposed farther from the exhaust port 304 thereby eliminating problems like burn off of catalytic converter unit 206 and poor breathing of the IC engine. In one implementation, the sleeve member 350 acts like a venturi member and is configured so that the catalytic converter unit 206 can be disposed at a distance at least 10 times a diameter of the exhaust port 304. [00045] Many modifications and variations of the present subject matter are possible within the spirit and scope of the present subject matter, in the light of above disclosure.

List of reference signs:

100 vehicle 25 209 second bend of exhaust pipe

101 internal combustion engine 210 cylinder head assembly

102 frame assembly 220 air-fuel supply device 103 rear wheel 301 intake port

105 grab rail 304 exhaust port

106 seat 30 307 downstream portion of

108 handlebar exhaust port

109 head light 310 upstream portion of exhaust 110 front wheel port

111 head pipe 320 insert member

114 front suspension 35 321 flange member

115 front fender 350 sleeve member

117 rear suspension 351 inner surface 121 fuel tank 352 outer surface

130 muffler body 360 confined region

200 exhaust pipe 40 AS inner cross-sectional area

201 inlet opening of exhaust pipe (sleeve member)

202 cylinder head cover ASU upstream cross-sectional area 203 cylinder head ASD down stream cross-sectional

204 cylinder block area

205 crankcase 45 A1 first cross-sectional area

206 catalytic converter unit A2/A2’ second cross-sectional area

208 first bend of exhaust pipe a first angle