EP3947932A2

EP3947932A2 - A motor vehicle comprising a combustion engine and exhaust system

Info

Publication number: EP3947932A2
Application number: EP20721818.1A
Authority: EP
Inventors: Bharaniram Senthilkumar; Saravanakumar Kalimuthu; Boobalan Mani
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2019-03-25
Filing date: 2020-03-18
Publication date: 2022-02-09
Also published as: CN113646513A; WO2020194338A2; WO2020194338A3; BR112021019177A2

Abstract

The present subject matter provides a combustion engine (141) for a motor vehicle (101). An exhaust system (300) includes a primary receiving portion (309) and a secondary receiving portion (307) capable of accommodating at least one primary conversion device (308) and at least one secondary conversion device (306) respectively. The primary receiving portion (309) is disposed at a downstream end portion of the discharge pipe (305). The secondary receiving portion (307) is disposed at an upstream of the primary receiving portion (309). The present subject matter provides minimal back pressure and at the same optimal functioning of the conversion device with long life of the conversion device.

Description

A COMBUSTION ENGINE AND A MOTOR VEHICLE THEREOF

TECHNICAL FIELD

[0001] The present subject matter, in general, relates to a motor vehicle including a combustion engine and, in particular relates to an exhaust system for the combustion engine of the motor vehicle.

BACKGROUND

[0002] Generally, two-wheeled or three-wheeled vehicles are provided with a power unit that primarily includes a combustion engine and/or an electric motor. The combustion engine, which is typically an internal combustion (IC) engine, is producing power/torque by combustion of air-fuel mixture. The resultant gases of the combustion process are scavenged by the exhaust system that includes piping to guide gases from the combustion engine. Also, the exhaust system includes a gas treatment device for the treatment of the gas. The treated gases are transmitted to the atmosphere.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.

[0004] Fig. 1 depicts an exemplary graphical representation of variation of temperature within the exhaust system with distance.

[0005] Fig. 2 depicts a right side view of an exemplary vehicle, in accordance with an embodiment of the present subject matter.

[0006] Fig. 3 depicts an enlarged side view of the power unit, in accordance with the embodiment as depicted in Fig. 2.

[0007] Fig. 4 depicts a bottom view of the vehicle, in accordance with the embodiment as depicted in Fig. 2.

[0008] Fig. 5 depicts right side view of an exemplary vehicle with selected parts, in accordance with a second embodiment of the present subject matter.

[0009] Fig. 6 depicts a bottom view of the vehicle, in accordance with the embodiment of Fig. 5. [00010] Fig. 7 depicts a right side view of an exemplary vehicle, in accordance with a third embodiment of the present subject matter.

[00011] Fig. 8 depicts an exemplary exhaust system for a combustion engine, in accordance with a fourth embodiment of the present subject matter.

[00012] Fig. 9 depicts an exemplary graphical representation of hydrocarbon conversion against time, in accordance with an embodiment of the present subject matter.

DETAILED DESCRIPTION

[00013] Conventionally, two-wheeled vehicles or three-wheeled vehicles are provided with power unit including the combustion engine and may have a traction motor. Also, the power unit includes various sub-systems like the air induction system that works in conjunction with the fuel supply system like carburetor or fuel injector. Air-fuel mixture is supplied to the combustion engine for combustion, which produces desired power and torque that is transferred to at least one wheel of the vehicle. Further, the exhaust system includes discharge pipe that transmits the gases generated during combustion process to a muffler. Generally, the gases that are emitted include harmful components including total hydrocarbons (THC), carbon monoxide (CO), and nitrogen oxides (NOx). There is a need for treating the harmful components prior to emitting the gases into the atmosphere through the muffler. Typically, the gas treatment device is used for the treatment of the aforementioned harmful components.

[00014] Thus, the gas treatment device is a critical element of the exhaust system, which helps in treating the harmful components. Therefore, the gas treatment device should be having higher conversion efficiency. To this end, the conversion efficiency of the gas treatment device depends on many factors including size/volume, or location of the gas treatment device in the exhaust system. Also, activation temperature of the gas treatment device is also to be considered. This is essential, especially, in cases of cold start as the catalyst would not have attained the requisite temperature of operation. Conventionally, a gas treatment device is disposed in proximity to the exhaust port to achieve quicker activation, but in such cases the bulkier conversion device is disposed in the piping that is connected to the exhaust port. By and large, vehicles like two-wheeled or three-wheeled vehicles, which offer a saddle -ride type layout, are having limitations in accommodating the gas treatment device due to layout constraints thereof. One challenge of the many challenges is to accommodate large size/volume of the gas treatment device within the piping. Firstly, exhaust piping connected to the exhaust port of the combustion engine is having a smaller thickness and such exhaust piping accommodating a large sized conversion device is a challenge. In order to accommodate the large sized conversion device, the exhaust piping should be provided with larger cross- section or a portion of the piping with larger cross-section. This would affect the structural strength of the piping. Further, the overall size of the exhaust pipe of the exhaust piping is increased, which increases the weight of the exhaust piping. As the piping extends from the combustion engine towards a muffler, which is disposed in the rear portion of the vehicle, the piping undergoes overhang due to the weight. This would require using of the piping with higher thickness and that in turn aggravates the problem of overhang.

[00015] Moreover, in some of the solutions provided in the art, a heated conversion device is used. However, the heating of the conversion device may require electrical windings or heat deflection mechanism that still makes the exhaust piping bulkier, which still experiences the aforementioned problems like the structural strength and increased size of the piping affecting the width or ground clearance.

[00016] Furthermore, in vehicles like motorcycles, the exhaust pipe extends to the rear from a front facing side of the combustion engine and then downward of the combustion engine. With respect to the user leg, at least a portion of the exhaust piping is near to the user leg or feet. At vehicle level, the exhaust piping is passing at a lower portion with respect to the lower portion of the combustion engine. Thus, in either of the cases, a large sized conversion device that would be disposed about the piping would project either in vehicle width direction or in downward direction. Projection of the exhaust piping, due to the accommodation of the conversion device, in lateral direction may interfere with the rider seating posture due to the heat dissipation or may come in contact with the user due to the projection, which is undesired. Moreover, such projection mandates use of a protection cover that again adds weight to the piping. Whereas, projection in a downwards direction of the vehicle would affect the ground clearance of the vehicle, which requires alteration of the engine height or other components affecting the center of gravity of the vehicle, seat height thereby adversely affecting the riding comfort.

[00017] Especially, in two-wheeled vehicles with swinging type IC engine, the IC engine is substantially at a lower portion of the vehicle. Also, the discharge pipe is also extending from the exhaust port to the muffler, which is disposed adjacent to the rear wheel. Therefore, the length of the discharge pipe is shorter. In such vehicles, while providing a gas treatment device, there is a need for eliminating effect of backpressure on the IC engine. As the back pressure would affect the performance of the engine.

[00018] Moreover, the conversion device includes a substrate that includes precious metals such as platinum, palladium and rhodium. This makes the conversion device a‘precious element’ of the exhaust system due to the cost premium involved. This substrate though active at an activation temperature ranges, but is sensitive to excessive high temperatures that could damage the substrate. Generally, the temperature about the exhaust piping at various points is dependent upon the distance of the point, at which temperature is taken, from the exhaust port. Fig. 1 depicts an exemplary graphical representation of temperature (T) drawn against distance (Dis), which is the distance from the exhaust port. The temperature near to the exhaust port is substantially high, which is at the region A. When the catalyst is disposed within the region A, the substrate of the conversion device would be exposed to the high temperature. This would deteriorate the performance of the conversion device instantly or with time. The substrate when damaged necessitates replacement of the conversion device, which involves higher cost. Also, replacement of the conversion device requires the exhaust system to be removed, which is a tedious process and require utmost care to assemble to the vehicle without any structural variation. The conversion device when disposed at the region C, which is far from the exhaust port where the temperature saturates, the light off of the conversion device, is not attained. This would make the conversion device obsolete as the conversion is attained. From Fig. 1, it is preferred that the conversion device is disposed about the exhaust system that offers optimum activation temperature that offers long life for the conversion device, which is preferably about the region B defined between the region A and region C. However, the conversion device even when disposed within the aforementioned region B, the conversion device is subjected to higher heat reception due to the larger area defined by the conversion device disposed near to the exhaust port. Moreover, large conversion device is prone to flame especially when disposed in proximity to the exhaust port. Due to the bulkier conversion device disposed near to the exhaust port, the higher surface area of the conversion device still has the strength related and space related issues of the exhaust pipe and also results in higher heat reception that reduces the life of the conversion device. Thus, the life the conversion device is reduced. Frequent replacement of the conversion device results in poor maintenance & ownership cost to the user & thus uneconomical. This problem is especially compounded for low cost vehicles which are used for commutation from point to point in different market segments.

[00019] Thus, from the above, one of the many challenges is to provide an exhaust system for a combustion engine with a conversion device that is having longevity in terms of its life/function and at the same time is capable of optimally treating the exhaust gases passing through. Also, additional challenge is to provide a compact exhaust system that does not affect the vehicle layout or does not necessitate layout change or tradeoff. Additionally, there is a need for addressing the other aforementioned short comings in the art.

[00020] Thus, there is a need for an exhaust system for a vehicle that addresses the aforementioned and other short comings and provide improved vehicle layout and vehicle performance.

[00021] Hence, the present subject matter provides a combustion engine with an exhaust system configured with a primary receiving portion for accommodating a primary conversion device and a secondary receiving portion capable of receiving a secondary conversion device, and the secondary conversion device is disposed upstream of the primary conversion device. [00022] The primary conversion device is having a volume substantially greater than a volume of the secondary conversion device. In other words, the overall conversion efficiency of the primary conversion device is greater than the secondary conversion device. It is a feature that the secondary conversion device with low volume occupies lesser space and is disposed within the discharge pipe.

[00023] The secondary conversion device is disposed at a pre-determined distance from an exhaust port end portion of an exhaust port of the combustion engine, wherein the secondary conversion device is in a region that is capable of providing earlier light-off and at the same time does not damage the substrate of the secondary conversion device. This improves the life of the secondary conversion device.

[00024] The secondary conversion device in spite of being disposed at a pre determined distance from the exhaust port is able to attain earlier light-off due to the smaller volume and the coating volume attains the activation temperature quickly.

[00025] The secondary conversion device as per the present subject matter is configured in the discharge pipe with ease as the diameter of the secondary conversion device is designed to be in the range of 1 to 1.8 times the diameter of the discharge pipe. Also, in one implementation, at least a portion of the secondary receiving portion is least partially visible to naked eye. Whereas, the primary receiving portion that accommodates a larger conversion device having a volume 1.2 to 5 times the volume of the secondary conversion device is disposed downstream of the exhaust system. In one implementation, at least a portion of the primary conversion device is at least partially disposed within a muffler assembly connected to a downstream end of the discharge pipe. It is a feature that, at higher rotation per minute of the combustion engine, the velocity/flow of the exhaust gas is quicker at the secondary conversion device where the treatment of the exhaust gas is less. However, the primary conversion device provided at least partially in the muffler assembly receives the exhaust gas at lower velocity whereby the treatment of exhaust gas is effective thereat due to reduced flow rate. [00026] It is a feature that the muffler assembly is capable of accommodating the primary conversion device with ease due to the larger cross-section of the muffler assembly.

[00027] In one implementation, the secondary conversion device is provided with a platinum or palladium or the like at a higher volume, which is capable of treating hydrocarbons, compared to the primary conversion device. Thus, the secondary conversion device is capable of treating the hydrocarbons that are one of the harmful components present in the exhaust gas immediately after start of the combustion engine. This helps in treating exhaust gases effectively even during cold-start conditions due to the earlier light-off of the secondary conversion device.

[00028] It is a feature that the secondary conversion device occupies lesser space in the discharge pipe. For example, the length of the secondary conversion device is small and can be accommodated between any two bends of the discharge pipe.

[00029] Further, the secondary conversion device can be accommodated immediate to a bend of the discharge pipe as the secondary conversion device does not require a larger change in cross-section of the secondary receiving portion that otherwise would complicate the securing process.

[00030] Furthermore, the exhaust system of the present subject matter can be implemented in a forwardly inclined engine or a vertical engine as the secondary conversion device occupies lesser space and does not affect the overall vehicle width or ground clearance. Additional feature being, the exhaust system can be implemented in combustion engine that is fixedly mounted to body frame or even in case of a swinging-type combustion engine. The secondary conversion device does not interfere with ancillary parts of the engine even in case of the swinging type engine.

[00031] The secondary conversion device is having a long axis disposed at an acute angle with respect to the piston axis of the combustion engine, whereby the discharge pipe is routed in proximity to the combustion engine providing a compact layout whereby sufficient ground clearance is also achieved. [00032] In one implementation, the discharge pipe is either a single tubular or double tubular type that is split to accommodate the secondary receiving portion, wherein the secondary receiving portion is welded to the discharge pipe ends.

[00033] The exhaust system of the present subject matter is capable of accommodating the conversion device in the discharge pipe with minimal back pressure and at the same optimal functioning of the conversion device with long life of the conversion device.

[00034] The term‘conversion device’ is not limited to a single conversion device and may include one or more devices that are accommodated in the exhaust system.

[00035] These and other advantages of the present subject matter would be described in greater detail in conjunction with the figures in the following description.

[00036] 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.

[0001] Fig. 1 (a) illustrates a side view of an exemplary motor vehicle (100) in accordance with the present subject matter. The depicted motor vehicle (100) is interchangeably referred to as a motorcycle (100). The motorcycle (100) includes a body frame (105) to support different parts of the motorcycle (100). The body frame (105) includes a head tube (110) at its front end portion. The head tube (110) supports a steering shaft (not shown) rotatably in a certain range. In an upper portion of the steering shaft a handlebar (115) is connected. The handlebar (115) is used to steer the motorcycle (100) and is connected to a front wheel (120) through the steering shaft that is in turn connected to a front fork assembly (125). At least an upper portion of the front wheel (120) is covered by a front fender (130), which prevents mud and water from getting deflected towards the steering shaft or rearward of the wheel (120).

[0002] In a front portion of the body frame (105) a fuel tank (135) is mounted and is disposed immediately behind the handlebar (115). In one embodiment, a power unit including an internal combustion (IC) engine (140) is mounted to the body frame (105). In the present embodiment, the power unit is fixedly mounted to the body frame (105). A seat (145) is placed behind the fuel tank (135). The seat (145) includes a front-rider portion and rear-pillion portion.

[0003] To provide visibility, a headlamp unit (150) is provided in the front portion of the motorcycle (100). The headlamp unit (150), in the present embodiment is mounted to the front fork assembly (125). The front fork assembly (125), which forms the front suspension system, serves as damping component. Similarly, a rear suspension system (165), which is a hydraulic damped arrangement in one implementation, is connected to the body frame (105). The rear suspension system (165) comprises of at least one rear suspension preferably on either sides of the motorcycle (100). However, in another embodiment, the motor vehicle (100) may have only one rear suspension, either on the left side, on the right side, at a lateral centre, or at an offset from the lateral centre of said motorcycle. Further, a swing arm (not shown) extending rearward is swingably connected to a lower rear portion of the body frame (105) and the swing arm is functionally connected to the rear suspension (165). A rear wheel (121) is rotatably supported at a rear end portion of the swing arm (170). Power/ torque generated by the power unit (140) is transmitted to the rear wheel (121) through a transmission system (not shown) which includes a chain drive, a belt drive, so as to drive and rotate the rear wheel (115). A rear fender (175) is provided for covering at least an upper side portion of the rear wheel (121) and prevents mud and water splashed by the rotating rear wheel (121) from reaching the muffler, the power unit (140) and other parts disposed close by.

[0004] The power unit with the combustion engine (140) is equipped with an exhaust system (200) that includes a discharge pipe (205) (shown in Fig. 3) connected to the combustion engine. Further, a muffler (180) is connected to the discharge pipe (205). The muffler (180), in the depicted embodiment, is disposed along one lateral side of the vehicle and extends rearward substantially adjacent to the rear wheel (121). [0005] To enhance the overall aesthetics of the vehicle (100) and to prevent undesired foreign particles from entering parts of the motorcycle, a plurality of panels (180A, 180B) are attached to a rear portion of the body frame (105).

[00037] Fig. 3 illustrates an enlarged side perspective of the power unit, in accordance with the embodiment of Fig. 2. The combustion engine (140) is disposed such that a piston axis (P-P’) is forwardly inclined, which means it is an acute angle with respect to an imaginary vertical line. Hereinafter, the terms ‘combustion engine’ and‘power unit’ are interchangeably. However, the term power unit is not limited to the combustion engine and may include an additional electrical motor that is capable of assisting the combination engine or is capable of operating independent of the combustion engine. The combustion engine (140) includes a cylinder portion defined by a cylinder block (202). The cylinder block (202) is mounted to a crankcase (204) of the combustion engine (140). The crankcase (204) is connected to the body frame (105) of the vehicle (100).

[00038] Further, the cylinder block (202) supports a cylinder head (201) that includes a valve assembly (not shown). The valve assembly enables entry of air- fuel mixture into the cylinder portion, where combustion of air-fuel mixture takes place. Subsequently, the valve assembly enables dissipation of the burnt gases from the cylinder portion. The air induction system along with air fuel supply system is connected to one side wall of the cylinder head (201) that is provided with an input port (not shown). In the present embodiment, the input port is provided in a rear portion of the cylinder head (201). Further, an exhaust port (203) is provided on another side wall of the cylinder head (201), which is substantially on the opposite of the input port. In the present implementation, the exhaust port (203) is provided on a front facing side wall of the cylinder head (201) and the exhaust system (200) is connected to the exhaust port (203).

[00039] The exhaust system (200) includes a discharge pipe (205) that connects the cylinder head (201) to the muffler (180). An upstream end portion of the discharge pipe (205) is connected to the exhaust port (203) of the cylinder head (201). The discharge pipe (205) extends downward towards one lateral side (RH/LH) of the vehicle (100) and then extends rearward towards the muffler (180). The exhaust system (200) is provided with a secondary receiving portion (207) that is capable of accommodating a secondary conversion device (206). The secondary conversion device (206) is disposed at a pre-determined distance from an exhaust port end portion of an exhaust port (203) of the combustion engine (140), and the pre-determined distance offers the desired activation temperature for the light-off of the secondary conversion device (206). Further, a primary receiving portion (209), capable of receiving a primary conversion device (208), is disposed at a downstream end portion of exhaust system (200). Thus, when considering the exhaust gas flow path, the secondary conversion device (206) is at an upstream with respect to the primary conversion device (208). In one implementation, the primary conversion device (208) can be disposed substantially after a mid-portion of the discharge pipe (205).

[00040] In one implementation, the secondary conversion device (206) is having a long axis (L-L’), along direction of flow of exhaust/ exhaust gas, disposed at an acute angle with respect to a piston axis (P-P’) of the combustion engine (140), whereby the discharge pipe (205) is routed in proximity to the combustion engine (140), specifically towards the periphery of the crankcase (204) providing a compact layout. As depicted in the present embodiment, the secondary receiving portion (207) is disposed inward away from the front wheel (120) (shown in Fig. 1) providing a compact power unit layout.

[00041] As depicted in Fig. 3, the secondary receiving portion (207) is capable of accommodating the secondary conversion device (206) having a diameter in the range of 1 to 1.8 times the diameter (D) of the discharge pipe (205). Also, in one implementation, at least a portion of the secondary receiving portion (207) is at least partially visible to naked eye (shown in Fig. 3). Also, the diameter of the secondary conversion device (206) offers poka-yoke fitment, as the primary conversion device (208) cannot be mounted at the secondary receiving portion (207) due to volume difference.

[00042] Further, the secondary conversion device (206) is having a volume substantially lesser than the volume of the primary conversions device (208), as the volume of the primary conversion device (208) is about 1.2 to 5 times the volume of the secondary conversion device. The coating volume of the primary conversion device is about 1.2 to 5 times of the secondary conversion device. In other words, the secondary conversion device (206) is having an overall conversion efficiency lesser than the overall conversion efficiency of the primary conversion device (208). Further, the secondary conversion device (206) is having a smaller volume or cross-sectional area is disposed optimally within the region (B), shown in Fig. 1. Further, from Fig. 1, after point B’, there occurs a temperature drop with greater inclination compared to region A, but the secondary conversion device (206) disposed in the discharge pipe (205) in the region B, due to the smaller volume, is capable of attaining the activation temperature quickly even during cold start. In an embodiment, the temperature at the region B is less than the equilibrium temperature, which is around 600 degrees centigrade for a typical single cylinder powertrain. Moreover, disposing the conversion devices (206/208) in the region C, after the point B”, would result in poor performance of the conversion device due to saturation of the temperature. Thus, according to the present subject matter, the secondary conversion device (206) achieves the light off earlier and at the same time is accommodated compactly within the discharge pipe (205).

[00043] In one implementation, the discharge pipe (205) is provided with a secondary receiving portion (207) that is capable of accommodating the secondary conversion device (206). The discharge pipe (205) can be of a single tubular construction or double tubular construction with any circular or non-circular cross section. In the depicted embodiment like vehicle (100) with substantial portion of the discharge pipe (205) being exposed is provided with double tubular construction, wherein two tubes are disposed concentrically about each other. The outer most tube of the two tubes acts as a protector from any person directly coming in contact with the inner tube that is carrying the exhaust gas. In one implementation, the outer tube is provided with perforations to enable cooling of the inner tube and still maintain the feature of protection from direct contact. This enables the secondary conversion device (206) to be disposed in proximity to the exhaust port (203) and the perforated construction enables in maintaining the temperature in the region B. Thus, the present subject matter enables the secondary conversion device (206) to be disposed in the discharge pipe (205) at a location in the range of 0-60% of length from the exhaust port (203), wherein the length is true length of the discharge pipe (205). The secondary receiving portion (207) at the desired location of the discharge pipe (205) is welded to the ends of the discharge pipe (205) that is split in order to accommodate the secondary receiving portion (207) thereat.

[00044] Also, as depicted in the present embodiment, the secondary receiving portion (207) is disposed between a first bend (211) and a second bend (212) of the discharge pipe (205). Further, the secondary conversion device (206), which is having smaller volume, accommodated by the secondary receiving portion (207) is disposed in proximity to either of the first bend (211) or the second bend (212) as the secondary receiving portion (207) would have a smaller volume compared to the volume required for the primary conversion device (208). Thus, the discharge pipe (205) of the present subject matter provides added feature that the secondary receiving portion (207) is accommodated immediate to the first bend (211) or the second bend (212). In one application, the secondary receiving portion (207) is having a cone shaped transition as the secondary receiving portion (207) is having a diameter greater than the diameter of the discharge pipe (205) and the cone shape is having an acute cone angle (a) with the long axis L-L’ in the direction of flow of the exhaust gases. As per an embodiment, this angle is in the range of 25-55 degrees. This enables in providing the secondary receiving portion (207) in the discharge pipe (205) with ease as the cone angle (a) provides smooth transition from the discharge pipe (205) to the secondary receiving portion (207).

[00045] In one embodiment, the secondary conversion device is provided with a temperature control mechanism, wherein the temperature control mechanism regulates the temperature thereof. For example, the temperature control mechanism is can be a heating mechanism that enables the conversion device in reaching earlier light-off. Whereas, in one implementation, the temperature control mechanism can be a cooling mechanism that cools the secondary conversion device to stay within the region B . For example, the heating mechanism can be an induction coil disposed about the secondary conversion device or a heat deflecting mechanism from the engine. Whereas, the cooling mechanism can be a fluid-cooling mechanism with a natural or force cooling system.

[00046] Fig. 4 depicts a bottom view of the vehicle (100), in accordance with the embodiment of Fig. 2. The primary conversion device (208) is disposed in the muffler assembly (180) of the vehicle (100), in the present embodiment. The muffler assembly (180) having a substantial volume is capable of accommodating the large size/volume primary conversion device (208) therein. Further, muffler assembly (180) disposed substantially adjacent to the rear wheel (121) of the vehicle (100) and the muffler assembly (180) is extending inclinedly upward and is well isolated from user legs & / or feet or from coming in contact with rider or pillion that could cause any burn etc. Further, the primary conversion device (208) is at least partially enclosed by the muffler assembly (180) connected to the discharge pipe (205) thereby retaining the heat for optimum functioning of the primary conversion device (208).

[00047] Further, in the depicted embodiment, the discharge pipe (205) includes a third bend (213) and a fourth bend (214) before getting connected to the muffler assembly (180). The portion of the discharge pipe (205) accommodating the secondary receiving portion (207) is substantially disposed between the first bend (211) and the second bend (212) & is substantially disposed in proximity to the lateral center of the vehicle 100, which is depicted by the longitudinal axis (F-R) drawn about the lateral center of the vehicle (100). The discharge pipe (205), subsequent to the second bend (212), extends substantially in the same line in longitudinal direction (F-R) and at a third bends (213) it extends in laterally outward direction. The discharge pipe (205) at a fourth bend (214) extends in outward direction and gets welded to the inlet of the muffler assembly (180). This keeps the discharge pipe (205) to be substantially inward with respect to a rider foot peg (215). Moreover, the secondary conversion device (206) is ahead of the second bend (212), wherein subsequent to the second bend (212) only the discharge pipe (205) passes downward of the combustion engine (140).

[00048] Fig. 5 illustrates a side view of another motor vehicle (101), in accordance with a second embodiment of the present subject matter. The combustion engine (141) is disposed such that a piston axis (P-P’) is forwardly inclined. The combustion engine (141) is fixedly mounted to a frame member (106) of the vehicle (101), wherein the combustion engine (141) is disposed below a step- through portion defined by the frame member (106). In an embodiment, the combustion engine (141) is mounted to lower portion of the frame member (106). The combustion engine (141) includes a cylinder portion defined by a cylinder block (202) and a cylinder head (201). The cylinder block (202) is mounted to a crankcase (not shown) of the combustion engine (141), wherein the combustion engine (141) is secured to the body frame (106) through the crankcase.

[00049] Further, the cylinder block (202) supports a cylinder head (201) that includes a valve assembly and inlet/exhaust ports (203). In this particular embodiment, the exhaust port (203) is provided on a side wall of the cylinder head (201), which is substantially facing downward (Dw). The exhaust system (300) gets functionally connected to the exhaust port (203). The exhaust system (300) includes a discharge pipe (305) that connects the cylinder head (201) to the muffler assembly (181). In the depicted implementation, the discharge pipe (305) extends rearward towards one lateral side (RH/LH) of the vehicle (101) by taking a first bend (311).

[00050] The exhaust system (300) is provided with a secondary receiving portion (307) that is capable of accommodating a secondary conversion device (306) therein. Further, a primary receiving portion (309), capable of receiving a primary conversion device (308), is disposed at a downstream end portion of exhaust system (300). As depicted, the primary conversion device (308) is accommodated by the muffler assembly (181) that is having larger volume and is substantially disposed adjacent to the rear wheel (121) of the vehicle (101). The exhaust gas from the combustion engine (141) first passes through the secondary conversion device (306) and subsequently through the primary conversion device (308). In one implementation, at least a portion of the secondary conversion device (306) is disposed substantially at a mid-portion of the discharge pipe (305), which is substantially within the region B as depicted in Fig. 1. In a preferred implementation, the secondary conversion device (306) is having a volume substantially lesser than the volume of the primary conversion device (308). Further, any undesired flame affecting the secondary conversion device 306 is less compared to the primary conversion device (308), as the smaller volume of the secondary conversion device (306) is having a smaller area. In other words, the secondary conversion device (306) is having an overall conversion lesser than the overall conversion efficiency of the primary conversion device (308). Moreover, the secondary conversion device (306), accommodated by the secondary receiving portion (307), in spite of being disposed in proximity to the exhaust port (203) is capable of providing an improved life / durability due to the smaller area/volume compared to the primary conversion device (308). Also, the secondary conversion device (306) attains early light-off temperature and enables in conversion immediately even during a cold- start condition.

[00051] Further, the motor vehicle (101) with substantial portion of the discharge pipe (305) being exposed is provided either as a single tubular construction or a double tubular construction. The secondary receiving portion (307) at the desired location of the discharge pipe (305) is welded to the ends of the discharge pipe

(305) that is split in order to accommodate the secondary receiving portion (307) thereat. Further, discharge pipe (305) in spite of passing substantially below the crankcase does not interfere with the crankcase as the secondary conversion device

(306) is having a smaller volume or cross-sectional area.

[00052] Also, in one implementation, the secondary receiving portion (307) is disposed immediately after the first bend (311) as the smaller cross-sectional area for accommodating the secondary conversion device (306) that can be accommodated immediate to the first bend (311). Further, the discharge pipe (305) undergoes a second bend (312) in an upward direction, which is a step up, subsequent to which the discharge pipe (305) is connected to the muffler assembly (181) that is extending inclinedly rearward. Also, the secondary receiving portion

(307) even if disposed ahead of the rider footrest (315), the smaller volume of the secondary conversion device (306) offers lesser heat dissipation, due to the exothermic reaction thereat, whereby the user foot placed above the rider footrest (315) is not subject to heating in spite of being in proximity. It is a feature that the present subject matter provides design flexibility without the need for major layout modifications of the vehicle (10)1.

[00053] Fig. 6 depicts a bottom view of the vehicle (101), in accordance with the embodiment of Fig. 5. The primary conversion device (308) is disposed in the muffler assembly (181) of the vehicle (100) as the muffler assembly is having a substantial volume for accommodating the large size/volume primary conversion device (308) therein. Further, muffler assembly (180) disposed substantially adjacent to the rear wheel (121) of the vehicle (100) and the muffler assembly (180) is extending inclinedly upward and is well isolated from user legs or from coming in contact with rider or pillion to cause any burn etc.

[00054] Further, in the depicted embodiment, the discharge pipe (305) subsequent to the first bend (312), which is the bend that changes the orientation of the discharge pipe (305) in the rearward direction, extends substantially in a longitudinal direction (F-R) and at a lateral off-set from a lateral center of the vehicle (101), wherein the lateral center is represented by the longitudinal axis (F- R) drawn about the lateral center. Further, the discharge pipe (305) is capable of accommodating the secondary conversion device (306) without the need for any additional reinforcements of the pipe (305). Moreover, the discharge pipe 305 along with the secondary receiving portion (307) is disposed substantially inward with respect to a rider foot peg (315). Moreover, the secondary conversion device (306) is ahead of the second bend (312), wherein subsequent to the second bend (312) only the discharge pipe (305) passes downward of the crankcase of the power unit/combustion engine (141).

[00055] Fig. 7 illustrates a side view of yet another motor vehicle (102), in accordance with a third embodiment of the present subject matter. The combustion engine (142) is disposed such that a piston axis (P-P’) is inclined at an acute angle with respect to an imaginary horizontal line. The combustion engine (142) is swingably connected a frame member (107) of the vehicle (102), wherein the combustion engine (142) is disposed rearward of a step-through portion defined by the frame member (107). The combustion engine 142 includes a cylinder portion defined by a cylinder block and a cylinder head (not shown). The cylinder block (202) (shown in Fig. 5) is mounted to a crankcase (404) of the combustion engine (142), wherein the combustion engine (142) connected to the body frame (107) by the crankcase using a toggle link (420). A muffler assembly (182) is also secured to the crankcase (404) of the combustion engine (142), wherein the muffler assembly (182) swings along with the combustion engine (142).

[00056] The exhaust port (not shown) is provided on side wall of the cylinder head, which is substantially facing downward (Dw), in the depicted implementation. The exhaust system (400) gets functionally connected to the exhaust port through a discharge pipe (405) that connects the cylinder head to the muffler assembly (182). The discharge pipe (405) passes through a space defined by the toggle link (420), which typically is having two arms extending substantially in longitudinal direction of the vehicle (100). In the depicted implementation, the discharge pipe (405) extends rearward towards one lateral side (RH/LH) of the vehicle (102) by taking a first bend (411). In one implementation, a secondary receiving portion (407) that is capable of accommodating a secondary conversion device (406) therein, is disposed immediate to the first bend (411), which is a region falling within the region B, as shown in Fig. 1. Further, a primary receiving portion (409), capable of receiving a primary conversion device (408), is disposed at a downstream end portion of exhaust system (400).

[00057] As depicted, the primary conversion device (408) is accommodated by the muffler assembly (182) that is having larger volume and is substantially disposed adjacent to the rear wheel (121) of the vehicle (102). The exhaust gas from the combustion engine (142) first passes through the secondary conversion device (406) and subsequently through the primary conversion device (408). The secondary conversion device (406) disposed in proximity to the exhaust port when compared to the primary conversion device (408) provides improved life & durability for both the devices as the secondary conversion device (406) with smaller area/volume is disposed near to the exhaust port and the primary conversion device with larger area is disposed away from the exhaust port (203) (shown in Fig.

3). [00058] Also, the secondary conversion device (406) with the smaller volume disposed in proximity to the exhaust port (203) offers less back pressure when compared to a primary conversion device disposed in a similar position thereby enhancing the performance of the powertrain as a whole. Further, the exhaust system (400) of the present motor vehicle (102) has the discharge pipe (405) passing substantially adjacent to the crankcase (404) of the combustion engine (142) does not interfere with the crankcase (404) as the secondary conversion device (406) is having a smaller volume or cross-sectional area. This enables in retaining the available layout of the combustion engine (142). Further, the combustion engine (142), which is swinging type, defines a locus region defined by the swinging motion the outer periphery portion of the secondary receiving portion (407) is away from body panels of the vehicle (102).

[00059] In one implementation, at least a portion of the secondary conversion device (406) is disposed ahead of an imaginary vertical line (C-C’) passing through a crankshaft (not shown) of the combustion engine (142). Thus, the exhaust system (400) of the present subject matter is compactly accommodated within the layout of the vehicle (102).

[00060] From the aforementioned exemplary embodiment, it is evident that the exhaust system of the present subject matter is adaptable to all kind of combustion engines whether lean-burn, rich-bum, short- stroke, or long- stroke.

[00061] Fig. 8 depicts an exemplary exhaust system for a combustion engine, in accordance with a fourth embodiment of the present subject matter. In the present embodiment, the combustion engine (not shown) is a rear inclined type having an inlet port in a front portion and an exhaust port in a rear portion thereof, and wherein a piston axis of the combustion engine is at an acute angle with respect to an imaginary vertical line. The exhaust system (500) includes a discharge pipe (505) having connection portion (525) that gets connected to the exhaust port (203) (as shown in Fig. 3) of the combustion engine. The discharge pipe (505) extends rearward from the combustion engine and then extends towards one of the lateral sides (RH/LH) of the vehicle. A secondary conversion device (506) is disposed about the discharge pipe (505), wherein the secondary conversion device (506) is accommodated by a secondary receiving porting (507). Further, a primary conversion device (508) with a higher volume or higher conversion efficiency is disposed downstream of the secondary conversion device (506), wherein the primary conversion device (508) can be accommodated within the discharge pipe

(505) or with a muffler assembly (183). Also, the secondary conversion device

(506) is disposed subsequent to a first bend (511) or subsequent to a second bend (512) depending on the activation temperature of the combustion engine.

[00062] Fig. 9 depicts a graphical representation of conversion of hydrocarbons by the conversion devices with time, in accordance with the embodiment of the present subject matter. Even though the present subject matter provides the primary conversion device (208, 308, 408, 508) offering an overall higher treatment or higher conversion with respect to the secondary conversion device (206, 306, 406, 506), the secondary conversion device (206, 306, 406, 506) can be so configured to treat the hydrocarbons higher compared to the primary conversion device (208, 308, 408, 508) through predetermined combination of the material composition of the at least one of the primary & secondary conversion devices. The secondary conversion device (206, 306, 406, 506) disposed about the exhaust system (200, 300, 400, 500) is having improved life & durability as the volume of the secondary conversion device is disposed within the region B offering quick activation at the same time away from excessive temperature. Further, the present subject matter enables use of either platinum or palladium at higher concentration in the secondary conversion device (206, 306, 406, 506) compared to the primary conversion device thereby enhancing its effectiveness as well as overcoming the contradiction of backpressure rise on the combustion chamber. As per an aspect of the present subject matter, the exhaust system is configured with a set of primary & secondary conversion devices such that the secondary one precedes & is substantially upstream of the primary conversion device. Curve D of the graph shows hydrocarbon (HC) conversion efficiency of the secondary conversion device (206, 306, 406, 506) as compared to the HC conversion efficiency of the primary conversion device (208, 308, 408, 508). Thus, the secondary conversion device (206, 306, 406, 506) having a high HC conversion efficiency is still having an overall conversion efficiency of exhaust gasses less than the overall conversion efficiency of the primary treatment device.

[00063] It is an advantageous feature that the even at higher rotation per minute (RPM) of the combustion engine, the velocity/flow of the exhaust gas is higher at the secondary conversion device where the treatment of the exhaust gas is less. However, the primary conversion device provided at least partially in the muffler assembly receives the exhaust gas at lower velocity whereby the exhaust the treatment of exhaust gas is effective thereat due to reduced flow rate.

[00064] It is a feature that, at higher rotation per minute of the combustion engine, the velocity/flow of the exhaust gas is higher at the secondary conversion device (206, 306, 406, 506) where the treatment of the exhaust gas is less but due to the higher HC treatment content in the secondary conversion device (206, 306, 406, 506) even at higher flow rate the conversion happens. The overall conversion may be less at the secondary conversion device (206, 306, 406, 506). Subsequently, when the exhaust gas reaches the primary conversion device (208, 308, 408, 508), the velocity is reduced and the larger volume thereof along with the reduced velocity enables in treating the remaining HC contents and other contents like NOx in the exhaust gas coming from the combustion engine (140, 141, 142). Thus, the exhaust system (200, 300, 400, 500) of the present subject matter offers improved efficiency, life & durability of the conversion devices and also effective treatment of the exhaust gas. Also, a compact layout of the power unit can be maintained without the need for any major vehicle layout changes.

[00065] The various embodiments described above can be combined to provide further embodiments. Also, aspects of the embodiments are not necessarily limited to specific embodiments. Depicted figures are for illustrative purposes, many modifications and variations of the present subject matter are possible within the scope of the present subject matter, in the light of above disclosure.

List of reference signs:

100/101/102 vehicle 110 head tube

105/106/107 body frame 115 handlebar 120 front wheel 407/507 secondary receiving

121 rear wheel portion

125 front fork assembly 25 208/308/

135 fuel tank 408/508 primary conversion 140/141/142 combustion engine device

145 seat 209/309/409 primary receiving 150 headlamp unit portion

165 rear suspension 30 211/311/411 first bend

180/181/ 212/312 second bend

182/183 muffler 213 third bend

200/300/ 214 fourth bend

400/500 exhaust system 420 toggle link

201 cylinder head 35 525 connection portion 202 cylinder block D diameter

203 exhaust port F-R longitudinal direction 204/404 crankcase C-C imaginary vertical 205/305/ line

405/505 discharge pipe 40 L-L' long axis

206/306/ P-P piston axis

406/506 secondary conversion RH/LH lateral side device a cone angle

207/307/

Claims

We claim:

1. A combustion engine (140, 141, 142) for a motor vehicle (100, 101, 102, 103), the combustion engine (140, 141, 142) connected to a frame member (105, 10, 107) of said motor vehicle (100, 101, 102, 103), said combustion engine (140, 141, 142) comprising:

a cylinder head (201); and

at least one exhaust system (200, 300, 400, 500) comprising at least one discharge pipe (205, 305, 405, 505), an upstream portion of said discharge pipe (205, 305, 405, 505) connected to an exhaust port (203) of said cylinder head (201);

characterized in that,

said exhaust system (200, 300, 400, 500) is configured with a primary receiving portion (209, 309, 409) and a secondary receiving portion (207, 307, 407, 507) capable of accommodating at least one primary conversion device (208, 308, 408, 508) and at least one secondary conversion device (206, 306, 406, 506) respectively, said primary receiving portion (209, 309, 409) disposed at a downstream end portion of said discharge pipe (205, 305, 405, 505), and said secondary receiving portion (207, 307, 407, 507) disposed upstream of said primary receiving portion (209, 309, 409).

2. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claiml, wherein said at least one primary conversion device (208, 308, 408, 508) constitutes a substrate volume substantially greater than a substrate volume of said at least one secondary conversion device (206, 306, 406,

506).

3. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claiml, wherein said secondary receiving portion (207, 307, 407,

507) is disposed at a pre-determined distance from an exhaust port end portion of said exhaust port (203) of said cylinder head (201), and wherein said secondary receiving portion (207, 307, 407, 507) is having a cone shape having an acute cone angle (a) with reference to a long axis (L-L’) along the direction of flow of exhaust.

4. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claim 3, wherein said acute cone angle (a) with reference to the long axis (L-L’) along the direction of flow of exhaust gas in a range of 25-55 degrees.

5. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claiml, wherein said secondary receiving portion (207, 307, 407, 507) is at least partially visible to naked eye and said primary receiving portion (209, 309, 409) is at least partially enclosed by a muffler assembly (180, 181, 182, 183) connected to said discharge pipe (205, 305, 405, 505) thereby retaining the heat for optimum functioning of the primary conversion device.

6. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claim 1, wherein said secondary conversion device (206, 306, 406, 506) is provided with at least one of platinum, palladium or the like at a higher concentration with respect to the concentration provided in said primary conversion device (208, 308, 408, 508).

7. The combustion engine (140) for the motor vehicle (100) as claimed in claim 1, wherein said combustion engine (140) is a having at least a piston axis (P- P’) inclined at an acute angle with respect to an imaginary vertical line and said combustion engine (140) is fixedly mounted to the body frame (105).

8. The combustion engine (141, 142) for the motor vehicle (101, 102) as claimed in claim 1, wherein said combustion engine (141, 142) is having at least a piston axis (P-P’) that is forwardly inclined, and wherein said combustion engine (141, 142) is connected to the body frame (106, 107) by at least one of swingable connection or fixed connection.

9. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claim 1, wherein said secondary receiving portion (207, 307, 407) is disposed in proximity to a first bend (211, 311, 411) that is secured to the cylinder head (201) of the combustion engine (140, 141, 142).

10. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claim 1, wherein said discharge pipe (205, 305, 405, 505) includes at least a portion of the secondary receiving portion (207, 307, 407, 507) disposed in a front portion with respect to an imaginary vertical partition line (C- C’) passing through a crankshaft of said combustion engine (140, 141, 142).

11. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claim 1, wherein said secondary conversion device (206, 306, 406, 506) has a long axis (L-L’) substantially disposed at an acute angle with respect to a position axis (P-P’) of the combustion engine (140, 141, 142).

12. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claim 1, wherein said discharge pipe (205, 305, 405, 505) is at least one of a single tubular or double tubular type construction, and wherein said discharge pipe (205, 305, 405, 505) with double tubular construction is provided with at least one perforation for temperature control.

13. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claim 1, wherein said secondary receiving portion (207, 307, 407, 507) is capable of being disposed immediately adjacent to at least one bend (211, 311, 411, 212, 312) of the discharge pipe (205, 305, 405, 505).

14. The combustion engine (140, 141, 142) for the motor vehicle (100, 101, 102) as claimed in claim 1, wherein said secondary conversion device (206, 306, 406, 506) is having a diameter substantially in range of 1 to 1.8 times of a diameter (D) of the discharge pipe (205, 305, 405, 505).

15. The combustion engine (140, 141, 142) for the motor vehicle (100, 101,

102) as claimed in claim 1, wherein said primary conversion device (208, 308, 408, 508) is having a volume in the range of 1.2 to 5 times of a volume of the secondary conversion device (206, 306, 406, 506).