TECHNICAL FIELD [0001] The present invention relates generally to a multi-wheeled vehicle, and more particularly to an exhaust system of a two or three wheeled vehicle. 5 BACKGROUND [0002] Generally, the exhaust system extends from the engine assembly towards a rear portion of the vehicle. In a two wheeled vehicle the exhaust system is typically disposed substantially below the rider & downstream of the engine assembly to ensure no or minimal physical contact of the rider or occupant with the exhaust system. This enables safe operation for the users as well. 10 as effective cooling of the exhaust system through aerodynamic effect of wind. In a typical three wheeled vehicle e.g. an auto rickshaw, the power train assembly (engine & transmission system) is disposed at the rear portion downstream of the rider. Often the power train along the exhaust is disposed either under the seat of the passenger or downstream of the passenger seat since this provides for best possible layout packaging for such type of vehicles while enabling ease of 15 service. Typical four wheeled vehicles have powertrain disposed on front side of the vehicle often referred as front engine layout. Such layout has adequate space in the front to configure the 0) disposition of the exhaust system such that a long exhaust pipe extends towards the rear to .TO discharge the exhaust gases. In a four wheeled vehicle with rear engine layout, the wheelbase of _0) the vehicle is relatively higher enabling disposition of the exhaust system at the rear of the seats. |Z -20 Typical three wheeled vehicle provides for higher ground clearance as compared to four ^ wheelers & thus has a challenge of mamtaining low center of gravity in disposition of the »- powertrain cum exhaust components to achieve good dynamic stability & performance. Four it wheeled vehicles have low center of gravity with trade-off on relatively lower ground clearance. £5 Collectively, the challenge of achieving compact vehicle size & optimal layout of powertrain en 25 system is significantly difficult in a three wheeled vehicle as compared to a four wheeled vehicle. o In such aforementioned automotive vehicles, evaporative fuel emission is generated in a fuel CO o tank thereof, particularly when they are parked in sun or exposed to a high temperature. h- [0003] Additionally, the exhaust gases arising out of combustion and burning of air-fuel mixture 30 is discharged to the atmosphere through a muffler wherein the main muffler function is to reduce CO the noise. The exhaust gases are composed of burnt and unbumt hydrocarbons, which cause air o ^PATENT OFFICE CH.ENNAI 0 32'' 1 0 *■ 1 8 1 8 10=51 o O pollution if it is freely emitted into the air. Therefore, it is necessary to prevent it from being emitted or discharged into the atmosphere. Hence, in modern times, vehicles are provided with an exhaust system having catalytic converter in the body of the muffler which enables the oxidation and reduction of the un-bumt gases, away from touch points and environmental 5 factors. For the catalytic converter to operate optimally, a specific temperature range is required. Therefore, the catalytic converter may be disposed in the exhaust pipe so as to maintain the required activation temperature. [0004] When the temperature of the catalytic converter is lower than the activation temperature 10 needed for the catalytic converter to exhibit its catalytic function, the catalytic converter fails to sufficiently exhibit its exhaust purification function. Therefore, when the temperature of the catalytic converter is lower than the required temperature, it must be increased as soon as possible so as to activate (warm up) the catalytic converter. The disposition of the catalytic converter in the exhaust system layout also plays a very crucial role in achieving required control 15 on the emissions as well as delivering good durability of the exhaust system itself. If the catalytic converter is disposed very close to the combustion chamber viz. close to the exhaust port of the [00022] Figure 2 shows that the structure formed by said incoming section (204), said second ^ bend (214), said middle section (206), said third bend (216) and said outgoing section (207) has a oo T- U-shaped profile. Further, as shown in Figure 2 said secondary catalytic converter assembly o d (205) is disposed in said middle section (206) of said exhaust gas passage pipe (201). As shown Is- ^ 30 the bend radius of curvature of said second bend (214) and said third bend (216) is purposely at h- least twice the diameter of said exhaust gas passage pipe (201) because of the layout constraints ,- of said multi-wheeled vehicle (101). The bend radius of curvature of said second bend (214) and o ^PATENT. OFFICE. CHENNAr . OV10'2G18 1Q'51 O ■ o said third bend (216) is same. Also, it must be noted that the diameter of said exhaust gas passage pipe (201) ranges between 20-25 mm. Further, in one embodiment this diameter range is selected is order to accommodate a secondary catalytic converter (302) without requiring any modifications. Hence, additional cost incurred for positioning catalytic converter inside said 5 exhaust gas passage pipe (201) is avoided. Furthermore, rigidity of the overall structure with U-shaped profile as described above is improved. [00023] Next, as per another embodiment of the present invention, in Figure 2 the vertical distance between said incoming section (204) and said outgoing portion end (207) ranges from 10 100 to 150 mm. The position of said secondary catalytic converter assembly (205) in said exhaust gas passage pipe (201) plays a very crucial role in determining the purification performance of secondary catalytic converter assembly (205) because if it is placed very close to said engine unit (102) it can result in creation of undesirable back pressure. Also, placing secondary catalytic converter assembly (205) very close to said engine unit (102) will lead to an 15 enormous increase in temperature of the catalytic converter. Such an increase in temperature can result in melting of the engine cowl of said engine unit (102). On the other hand if it is placed too far, a very high activation time will be required for the catalytic converter and temperature can adversely affect the performance of the muffler (208) by heating said muffler (208) and the engine service cabin (103), thereby causing discomfort to the passenger. Hence, in one 20 embodiment said secondary catalytic converter assembly (205) is disposed at an optimum distance from said exhaust port end (202) and said muffler (208). Furthermore, there is an activation temperature needed for catalytic converters to exhibit their catalytic function therefore, in one embodiment said secondary catalytic converter assembly (205) is positioned in proximity with said engine unit (102) in order to achieve the required temperature in a convenient and fast 25 manner. [00024] Figure 3 shows a graph for temperature of exhaust pipe, within pre-determined time t 30 seconds after engine start-up as a function of distance from said exhaust port end (202). Moreover, in one embodiment said secondary catalytic converter (205) is placed at a pre- ATENL OFFICE CHENNAI 03./1Q/2O18 10=51 8 determined range of 0-60% of the true length of said exhaust gas passage pipe (201) so as to get the activation time for the catalyst more steeply, which generally drops drastically at 60% of the length as shown in Figure 3. Hence, said secondary catalytic converter (205) with afore explained configuration is disposed within a pre-determined distance (curvilinear) range for 5 additional purification performance by said secondary catalytic converter (205). [00025] Figure 4, is an exploded view of said secondary catalytic converter assembly (205) as per one embodiment of present invention, said secondary catalytic converter assembly (205) includes an assembly sleeve (301), an upstream bend adaptor member (303), a downstream bend adaptor 10 member (304), and a secondary catalytic converter (302). In an embodiment, said upstream bend adaptor member (303) is formed by welding at least two sheet metal parts (303a, 303b). Further, in one embodiment, said downstream bend adaptor member (304) is formed by welding at least two sheet metal parts (304a, 304b). Furthermore, said upstream bend adaptor member (303), said downstream bend adaptor member (304) and said secondary catalytic converter (302) is 15 purposely encapsulated within said assembly sleeve (301) because it is important to prevent the heat dissipation from said secondary catalytic converter (302). Thus, said assembly sleeve (301) serves to deliver two functions. Firstly, it prevents the increase in the cabin temperature and hence passenger discomfort is avoided. Secondly, it serves to maintain the optimum temperature required for the catalytic converter to perform purification in an efficient manner. In an 20 embodiment, said assembly sleeve 301 is formed by welding at least two sheet metal parts (301a, 301b). In one embodiment said assembly sleeve (301) is separated from said secondary catalytic converter (302), said upstream bend adaptor member (303) and said downstream bend adaptor member (304) by an air gap which further enhances its function of preventing heat dissipation as discussed above and additionally provide rigidity to the structure. 25 [00026] 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. 30 AT E N T OFFICE C HEWN Al_. ...Q 3 / 1 G / 2018 19=51 9 List of Reference Siens - 101 Multi-wheeled vehicle 102 Engine unit 103 Engine service cabin 5 104 Exhaust system 201 Exhaust gas passage pipe 202 Exhaust port end 203 First bend 204 Incoming section 10 205 Secondary catalytic converter assembly 206 Middle section 207 Outgoing section 208 Muffler U) to 209 Muffler inlet °- 15 210 Muffler first portion CD [TitI 211 Primary catalytic converter CN 5= 212 Muffler inlet passage member fForr 213 Incoming portion end to 214 Second bend . O £- 20 215 Outgoing portion end o 216 Third bend CO o 301 Assembly sleeve 17/21 302 Secondary catalytic converter ^ 303 Upstream bend adaptor member ^2 25 304 Downstream bend adaptor member gP A T E NT . OTT I_C_E_._ CHE N. N A2J_ _. J-L3 / 1 Q / 2 0 1 8 10= 5.1 i io O We Claim: 1. An exhaust system (104) for a three-wheeled vehicle (101), said vehicle (101) comprises an engine unit (102) disposed at the rear side, said engine unit (102) includes an exhaust port end (202); 5 . said exhaust system (104) comprising: a muffler (208) including a muffler inlet (209), a muffler first portion (210), a muffler inlet passage member (212), and a primary catalytic converter (211); and an exhaust gas passage pipe (201) includes a secondary catalytic converter assembly (205), an incoming portion end (213) and an outgoing portion end (215), wherein said 10 incoming portion end (213) is connected to said exhaust port end (202) and said outgoing portion end (215) connected to said muffler inlet (209). 2. The exhaust system (104) as claimed in claim 1, wherein said muffler (208) is mounted at hind side of said engine unit (102). 15 3. The exhaust system (104) as claimed in claim 1, wherein said exhaust gas passage pipe (201) includes a first bend (203), an incoming section (204), a second bend (214), a middle section (206), a third bend (216) and an outgoing section (207). 4. The exhaust system (104) as claimed in claim 1, wherein said secondary catalytic 20 converter assembly (205) is disposed in said middle section (206) of said exhaust gas passage pipe (201) between said second bend (214) of said exhaust gas passage pipe (201) and said third bend (216) of said exhaust gas passage pipe (201). 5. The exhaust system (104) as claimed in claim 1, wherein said secondary catalytic 25. converter assembly (205) disposed in said middle section (206) of said exhaust gas passage pipe (201) is perpendicular to the ground when said multi-wheeled vehicle (101) is viewed from the rear direction. T EM T OF FIX E " C_H_EM N AX _ .0.3^ 1 0_/.2JD.1 8 10= 5 1 10 6. The exhaust system (104) as claimed in claim 3, wherein the bend radius of curvature of said second bend (214) and said third bend (216) is at least twice the diameter of said exhaust gas passage pipe (201). 7. The exhaust system (104) as claimed in claim 6, wherein the diameter of said exhaust gas passage pipe (201) ranges between 20-25 mm. 8. The exhaust system (104) as claimed in claim 6,. wherein the bend radius of curvature of said second bend (214) and said third bend (216) is same. 9. The exhaust system (104) as claimed in claim 5, wherein the structure formed by said incoming section (204), said second bend (215), said middle section (206), said third bend (216) and said outgoing section (207) has a U-shaped profile. 15 10. The exhaust system (104) as claimed in claim 6, wherein the vertical distance between said incoming section (204) and said outgoing section (207) ranges between 100-150 U) CO Q_ .3* 20 11. The exhaust system (104) as claimed in claim 1, wherein said secondary catalytic I— converter assembly (205) includes an assembly sleeve (301), an upstream bend CN _ adaptor member (303), a downstream bend adaptor member (304), and a secondary Q catalytic converter (302). 25 12. The exhaust system (104) as claimed in claim 4, wherein said secondary catalytic converter assembly (205) is position said exhaust gas passage pipe (201). CO o CO converter assembly (205) is positioned in a range of 0-60 per cent of the true length of o CO J^ 13. The exhaust system (104) as claimed in claim 4, wherein said secondary catalytic h- 30 converter (302) covers at least 65-70 per cent of said middle section (206). oo o CN 14. The exhaust system (104) as claimed in claim 4, wherein said assembly sleeve (301) is made up of at least two sheet metal parts (301a, 301b). SPATE NT OFFICE ..CHEMNAI.::. Q31?'1'O/2"0I S. 10*51 10 15. The exhaust system (104) as claimed in claim 13, wherein said assembly sleeve (301) encompasses said upstream bend adaptor member (303) made up of at least two sheet metal parts (303a, 303b). 16. The exhaust system (104) as claimed in claim 17, wherein said upstream bend adaptor member (303) is connected on one end to said incoming section (204) of said exhaust gas passage pipe (201) and on other end connected to said secondary catalytic converter (302). 17. The exhaust system (104) as claimed in claim 13, wherein said assembly sleeve (301) encompasses said downstream bend adaptor member (304) made up of at least of two sheet metal parts (304a, 304b). 15 18. The exhaust system.(104) as claimed in claim 19, wherein said downstream bend adaptor member (304) is connected on one end to said outgoing section (207) of said fl) exhaust gas passage pipe (201) and on other end connected to said secondary catalytic "* converter (302). _0) ~ 20 19. The exhaust system (104) as claimed in claim 1, wherein said primary catalytic E o oT converter (211) is disposed in proximity of said muffler inlet (209) on said muffler inlet passage member (212). ^ 20. The exhaust system (104) as claimed in claim 1, wherein said primary catalytic CO ® 25 converter (211) is positioned in said muffler first portion (210) of said muffler (208). CO o co PntiMl thH ?fth J4 nf J-'r^""^ p£^^>' £N Chandan Chavan £ Head IP T- 30 TVS Motor Company Ltd. co o CNI o P AT E N T OFFICE C RE N. N1 AI .0'33/.TJE)_A 2 0.1.8. 1 0 L 5 1. O ^I