CN112867850A

CN112867850A - Exhaust system for three-wheeled vehicle

Info

Publication number: CN112867850A
Application number: CN201980064729.6A
Authority: CN
Inventors: B·森蒂尔库马尔; B·玛尼
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2018-10-01
Filing date: 2019-09-30
Publication date: 2021-05-28
Also published as: MX2021003802A; WO2020070754A1; PE20212013A1

Abstract

The present subject matter discusses catalyst mounting arrangements for multi-wheeled vehicle exhaust systems. The present subject matter proposes an arrangement for increasing the conversion capacity of a catalytic converter by implementing two catalytic converters at different locations, wherein the conversion capacity of a catalytic converter is approximately directly proportional to the size of the catalyst. The main catalytic converter is positioned inside the first muffler section and the auxiliary catalytic assembly is located on the exhaust pipe a predetermined distance from the engine unit and the muffler inlet. Further, various layout challenges associated with multi-wheeled vehicles are addressed by implementing the above-described solution.

Description

Exhaust system for three-wheeled vehicle

Technical Field

The present invention relates generally to a multi-wheeled vehicle and more particularly to an exhaust system for a two-or three-wheeled vehicle.

Background

Typically, the exhaust system extends from the engine assembly towards the rear of the vehicle. In two-wheeled vehicles, the exhaust system is typically disposed substantially beneath the driver and downstream of the engine assembly to ensure that there is no or only minimal physical contact between the driver or occupant and the exhaust system. This enables safe operation for the user and efficient cooling of the exhaust system by the aerodynamic effect of the wind. In a typical three-wheeled vehicle, such as an auto tricycle (auto rickshaw), the drive train assembly (engine and drive train) is disposed downstream of the driver at the rear. The drive train along the exhaust duct is usually arranged below or downstream of the passenger seat, as this provides the best possible layout package for this type of vehicle while making maintenance easy. A typical four-wheel vehicle has a drive train disposed on the front side of the vehicle, which is commonly referred to as a front engine arrangement. This arrangement has enough space at the front to configure the arrangement of the exhaust system so that the longer exhaust pipe extends toward the rear to discharge the exhaust gas. In a four-wheeled vehicle with a rear engine layout, the wheelbase of the vehicle is relatively high, enabling the exhaust system to be located at the rear of the seat. Typical three-wheeled vehicles provide higher ground clearance than four-wheeled vehicles, and therefore face the challenge of maintaining a low center of gravity for good dynamic stability and performance when arranging the drive train and the exhaust components. Four-wheeled vehicles have a low center of gravity, with a trade-off being made for a relatively low ground clearance. In general, the challenge of achieving compact vehicle size and optimal layout of the drive train is very difficult in three-wheeled vehicles as compared to four-wheeled vehicles. In such motor vehicles, evaporative fuel emissions are generated in their fuel tanks, especially when they are parked in the sun or exposed to high temperatures.

In addition, exhaust gas generated due to the incineration and combustion of the air-fuel mixture is discharged to the atmosphere through a muffler, the main function of which is to reduce noise. The exhaust gas consists of completely burned and incompletely burned hydrocarbons, which can cause air pollution if the hydrocarbons are freely discharged to the air. Therefore, it is necessary to prevent the hydrocarbons from being discharged or discharged into the atmosphere. Therefore, in modern vehicles, in the muffler body, there is provided an exhaust system having a catalytic converter capable of oxidizing and reducing incompletely combusted gases, away from contact points and environmental factors. For optimal operation of the catalytic converter, a specific temperature range is required. Thus, a catalytic converter may be provided in the exhaust pipe to maintain the desired activation temperature.

When the temperature of the catalytic converter is lower than the activation temperature required for the catalytic converter to exhibit its catalytic function, the catalytic converter cannot sufficiently exhibit its emission purification function. Therefore, when the temperature of the catalytic converter is lower than the required temperature, it is necessary to raise the temperature as quickly as possible to activate (warm up) the catalytic converter. The placement of the catalytic converter in the layout of the exhaust system also plays a crucial role in achieving the desired control of the emissions and in achieving good durability of the exhaust system itself. If the catalytic converter is placed very close to the combustion chamber, i.e. close to the exhaust port of the cylinder head assembly, this will result in back pressure, thereby hindering a smooth and efficient combustion performance of the engine assembly. Furthermore, placing the catalytic converter very close to the engine will result in a substantial increase in the temperature of the catalytic converter. This increase in temperature may cause the engine cowling, which is typically made of plastic, to melt. On the other hand, if placed too far, a very long activation time will be required, which will render the catalytic converter ineffective in reducing emissions. In the case of three-wheeled vehicles, there are additional challenges in that the increase in temperature of the catalytic converter can heat the muffler, the driveline components, and the engine service compartment, causing discomfort to the occupants, and possibly also leading to a durability failure of one or more components of the driveline.

To effectively reduce emissions, larger sized catalytic converters are preferred. However, for a given vehicle layout and its driveline requirements, factors such as space, cost, performance, durability, etc., need to be considered to determine the optimal dimensions. The conversion capacity of a catalytic converter is directly proportional to the size, volume and effective surface area of the catalyst used. The volume of the catalyst can be increased by increasing the length or volume of the catalyst. Most standard converters use an internal "honeycomb" structure with 400-600 cells per square inch. If the engine produces more gas at a higher rate, existing catalytic converters restrict gas flow and do not treat the toxic substances quickly enough, thereby slowing the overall process of decomposing higher levels of toxic gases into less harmful gases. This increases the load on the catalytic converter due to the increased excess fuel burning exhaust. Furthermore, there are various layout challenges associated (such as ground clearance, maintenance cabin size, etc.) that need to be addressed in a vehicle to achieve the above objectives. Further, in general, the size of the muffler is limited and cannot be increased without facing various obstacles. Therefore, it is necessary to achieve an optimum purification rate while solving all the above problems.

Another challenge arises in order to support an exhaust system including an exhaust pipe and an exhaust muffler at a support portion on a vehicle body, an engine body, or the like. This results in a larger frame, resulting in a less compact vehicle, and additionally, therefore, a disadvantage of implementing a larger catalytic converter in a form that undesirably increases the weight and cost of the vehicle. It is therefore an object of the present invention to provide an improved catalytic converter system that solves all of the above problems.

Drawings

The present subject matter is described in detail with reference to the accompanying drawings. The same reference numbers will be used throughout the drawings to refer to like features and components.

FIG. 1 illustrates a rear side view of an exemplary multi-wheeled vehicle according to an embodiment of the present subject matter.

Fig. 2 shows a discharge unit and a muffler assembly.

Fig. 3 shows a graph of the temperature of the exhaust pipe as a function of the distance from the exhaust port after 1 minute of engine start-up.

FIG. 4 shows an exploded view of the secondary catalytic converter assembly.

Detailed Description

The present invention relates to an exhaust system for an engine of a vehicle, which is designed to reduce emissions therefrom. It is desirable to provide an improved catalytic converter system in which at least one catalytic converter is supplied with engine exhaust gas that is free of hydrocarbons or has a reduced hydrocarbon content to a value below a predetermined value. More particularly, the present invention relates to overcoming the pollution problems associated with engines. In addition, during start-up, conventional catalytic converter systems may not have achieved efficient operating performance, and engine exhaust systems emit large amounts of hydrocarbon gases. Catalysts used in catalytic converter systems are typically inactive or inactive at ambient temperatures and must reach high temperatures, typically in the range of 300-. Generally, the temperature of the catalyst is increased by contact with high-temperature exhaust gas from the engine.

The combination of the continuous contact with those gases and the exothermic nature of the oxidation reactions occurring at the catalyst maintains the catalyst at an elevated temperature. The catalytic converter can convert 50% of carbon monoxide, hydrocarbon or NO_xIs referred to as the "light-off" temperature of the converter. However, during start-up of a commercial engine, the amount of carbon monoxide and hydrocarbons in the exhaust gas is higher than during normal engine operation. Theoretically, it is preferable to place the catalytic converter as close to the engine as physically possible to minimize the emission of pollutants during the initial start-up of the engine.

The closer the catalyst is to the engine, the hotter the exhaust gas is in contact with the catalyst and the faster the temperature of the catalyst rises to an effective operating level. However, due to space constraints in most vehicles, it is not practically feasible to locate the entire amount of catalyst in the system close to the engine.

Two catalytic converters may be used and load distributed among them to address the problem of achieving effective performance of the exhaust system without overloading the catalytic converters. According to a known technique, two catalytic converters have been used and a main catalyst is disposed between an upstream curved portion and a downstream portion of a combustion chamber exhaust pipe. Further, the main catalyst is configured to purify most of the gas discharged from the combustion chamber. Thus, a need arises to modify the exhaust pipe to accommodate the main catalyst. This significantly increases the cross-sectional area of the discharge pipe and makes it difficult to achieve a compact and optimal layout.

The conversion capacity of a catalytic converter is directly proportional to the size of the catalyst used. In accordance with one aspect of the subject invention, an exhaust system includes a primary catalytic converter and a secondary catalytic converter. The diameter of the auxiliary catalytic converter is designed to be within a range suitable for positioning it with the exhaust pipe without any undesirable modification, and thus layout restrictions are easily solved. In addition, the auxiliary catalytic converter is placed within a predetermined distance range, thereby obtaining a minimum activation time and a steep rise rate of temperature of the catalyst. According to one aspect of the invention, the predetermined distance ranges between 0-60% of the true length of the pipe, since the activation time drops sharply after 60% of the length.

The subject of the invention is therefore directed to an exhaust system in which the activation time of the catalytic converter is reduced due to the presence of a further catalytic converter placed closer to the exhaust port end (on the exhaust pipe). In the following description, the foregoing and other aspects of the present subject matter will be described in more detail in conjunction with the accompanying drawings.

Fig. 1 illustrates a rear side view of an exemplary three-wheeled vehicle (101) with an exhaust system (104) connected thereto, in accordance with embodiments of the present subject matter. The present subject matter is applicable to all types of vehicles having three or more wheels and an engine unit (102) disposed on the rear side. Therefore, hereinafter, it will be referred to as a three-wheeled vehicle or vehicle. The vehicle comprises an engine service bay (103), the engine service bay (103) comprising an engine unit (102) and an exhaust system (104). In fig. 1, the engine unit (102) is disposed in the engine service bay (103) located at the rear of the vehicle (101). Further, the engine unit (102) comprises at least one discharge port end.

Fig. 2 is an enlarged perspective view of the exhaust system (104) according to an embodiment of the present invention, the exhaust system (104) including an exhaust gas passage pipe (201) that takes exhaust gas from the engine unit (102) and a muffler (208) that provides an expansion volume for the exhaust gas to lose its energy to reduce the noise level. Further, the exhaust gas passage pipe (201) comprises a secondary catalytic converter assembly (205), an inlet portion end (213) and an outlet portion end (215), wherein the inlet portion end (213) is connected to the exhaust port end (202) of the engine unit (102) and the outlet portion end (215) is connected to the muffler inlet 209 of the muffler 208.

Further, the muffler (208) includes a muffler first portion (210), a muffler inlet channel member (212), and a main catalytic converter (211). Further, the main catalytic converter (211) is positioned within the muffler first portion (210) and on the muffler inlet channel member (212) near the muffler inlet (209). Fig. 2 also shows the exhaust gas passage pipe (201), the exhaust gas passage pipe (201) further comprising a first bend (203), an entry section (204), an entry portion end (213), a second bend (214), an intermediate section (206), a third bend (216), and an exit portion end (215). Meanwhile, a secondary catalytic converter unit (205) is disposed in the intermediate section (206) of the exhaust gas passage pipe (201) between the second bent portion (214) of the exhaust gas passage pipe (201) and the third bent portion (216) of the exhaust gas passage pipe (201). According to one embodiment, the secondary catalytic converter assembly (205) is positioned in the middle section (206), both perpendicular to the ground when the three-wheeled vehicle (101) is viewed from the rear side. Therefore, the vehicle horizontal layout restriction can be easily solved without sacrificing the purification efficiency of the catalytic converter.

Fig. 2 shows that the structure formed by the entry section (204), the second bend (214), the intermediate section (206), the third bend (216) and the exit section (207) has a U-shaped profile. Further, as shown in fig. 2, the auxiliary catalytic converter assembly (205) is disposed in the intermediate section (206) of the exhaust gas passage pipe (201). As shown in the drawing, intentionally, the radius of curvature of the second curved portion (214) and the third curved portion (216) is at least twice the diameter of the exhaust gas passage pipe (201) due to layout restrictions of the multi-wheeled vehicle (101). The second curved portion (214) and the third curved portion (216) have the same radius of curvature. Also, it should be noted that the diameter of the exhaust gas passage pipe (201) is in the range of 20-25 mm. Further, in one embodiment, the range of diameters is selected to accommodate the secondary catalytic converter (302) without requiring any modification. Therefore, the extra cost of positioning the catalytic converter inside the exhaust gas passage pipe (201) is avoided. Furthermore, the rigidity of the overall structure with the U-shaped profile as described above is improved.

Next, according to another embodiment of the present invention, in FIG. 2, the vertical distance between the entry section (204) and the exit section end (207) is in the range of 100 and 150 mm. The position of the secondary catalytic converter assembly (205) in the exhaust gas passage pipe (201) plays a crucial role in determining the purification performance of the secondary catalytic converter assembly (205), since if the secondary catalytic converter assembly (205) is placed very close to the engine unit (102), it may result in an undesirable back pressure. Also, placing the secondary catalytic converter assembly (205) very close to the engine unit (102) will result in a substantial increase in the temperature of the catalytic converter. This increase in temperature may cause the engine cowling of the engine unit (102) to melt. On the other hand, if the secondary catalytic converter assembly is placed too far, the catalytic converter will require a very long activation time and the temperature by heating the muffler (208) and engine service compartment (103) may adversely affect the performance of the muffler (208), causing passenger discomfort. Thus, in one embodiment, the secondary catalytic converter assembly (205) is disposed at an optimal distance from the discharge port end (202) and the muffler (208). Furthermore, there is an activation temperature required for the catalytic converters to exhibit their catalytic function, and therefore, in one embodiment, the secondary catalytic converter assembly (205) is positioned in the vicinity of the engine unit (102) to reach the required temperature in a convenient and fast manner.

Fig. 3 shows a graph of the temperature of the exhaust pipe as a function of distance from the exhaust port end (202) within a predetermined time t seconds after engine start-up. Further, in one embodiment, the auxiliary catalytic converter (205) is placed in a predetermined range of 0-60% of the actual length of the exhaust gas passage pipe (201), so that the activation time of the catalyst is steeper, as shown in fig. 3, and the temperature drops sharply at 60% of the length. Therefore, the auxiliary catalytic converter (205) having the aforementioned configuration is disposed within a predetermined distance (curve) range to obtain additional purification performance by the auxiliary catalytic converter (205).

Fig. 4 is an exploded view of the secondary catalytic converter assembly (205), the secondary catalytic converter assembly (205) including an assembly sleeve (301), an upstream bend adapter member (303), a downstream bend adapter member (304), and a secondary catalytic converter (302), according to one embodiment of the invention. In an embodiment, the upstream bend adapter member (303) is formed by welding at least two sheet metal parts (303a, 303 b). Further, in one embodiment, the downstream bend adapter member (304) is formed by welding at least two sheet metal parts (304a, 304 b). Furthermore, deliberately, the upstream bend adapter member (303), the downstream bend adapter member (304) and the secondary catalytic converter (302) are encapsulated within the assembly sleeve (301), as it is important to prevent heat dissipation from the secondary catalytic converter (302). Thus, the assembly sleeve (301) serves two functions. First, the assembled sleeve prevents the temperature in the cabin from rising and thus avoids the passengers from feeling uncomfortable. Second, the assembly sleeve is used to maintain the optimum temperature required for the catalytic converter to perform the purification in an efficient manner. In an embodiment, the assembly sleeve 301 is formed by welding at least two sheet metal parts (301a, 301 b). In one embodiment, the assembly sleeve (301) is separated from the secondary catalytic converter (302), the upstream bend adapter member (303) and the downstream bend adapter member (304) by an air gap, which further enhances the function of preventing heat dissipation as described above and additionally provides rigidity to the structure.

It should be understood that 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 light of the above disclosure. Therefore, within the scope of the claims of the present subject matter, the present disclosure may be practiced otherwise than as specifically described.

List of reference numerals

101 multi-wheel vehicle

102 engine unit

103 engine maintenance cabin

104 exhaust system

201 waste gas channel pipe

202 discharge port end

203 first bend

204 entry section

205 auxiliary catalytic converter assembly

206 middle section

207 exit segment

208 muffler

209 muffler inlet

210 muffler first part

211 main catalytic converter

212 muffler inlet channel member

213 enter into partial end

214 second bend

215 exit part end

216 third bend

301 assembling sleeve

302 auxiliary catalytic converter

303 upstream bend adapter member

304 downstream bend adapter member

Claims

1. An exhaust system (104) for a three-wheeled vehicle (101), the vehicle (101) comprising an engine unit (102) arranged at the rear side,

the engine unit (102) comprises an exhaust port end (202);

the exhaust system (104) comprises:

a muffler (208), the muffler (208) comprising a muffler inlet (209), a muffler first portion (210), a muffler inlet channel member (212), and a main catalytic converter (211); and

-an exhaust gas passage pipe (201), the exhaust gas passage pipe (201) comprising a secondary catalytic converter assembly (205), an entry portion end (213) and an exit portion end (215), wherein the entry portion end (213) is connected to the exhaust port end (202) and the exit portion end (215) is connected to the muffler inlet (209).

2. The exhaust system (104) of claim 1, wherein the muffler (208) is mounted on a rear side of the engine unit (102).

3. The exhaust system (104) of claim 1, wherein the exhaust gas passage tube (201) includes a first bend (203), an entry section (204), a second bend (214), an intermediate section (206), a third bend (216), and an exit section (207).

4. The exhaust system (104) according to claim 1, wherein the secondary catalytic converter assembly (205) is disposed in the intermediate section (206) of the exhaust gas passage pipe (201) between the second bend (214) of the exhaust gas passage pipe (201) and the third bend (216) of the exhaust gas passage pipe (201).

5. The exhaust system (104) according to claim 1, wherein the auxiliary catalytic converter assembly (205) disposed in the middle section (206) of the exhaust gas passage pipe (201) is perpendicular to the ground when the multi-wheeled vehicle (101) is viewed from behind.

6. The exhaust system (104) according to claim 3, wherein a radius of curvature of the second bend (214) and the third bend (216) is at least twice a diameter of the exhaust gas passage pipe (201).

7. The exhaust system (104) according to claim 6, wherein the exhaust gas passage pipe (201) has a diameter in a range between 20mm-25 mm.

8. The exhaust system (104) of claim 6, wherein the radii of curvature of the second bend (214) and the third bend (216) are the same.

9. The exhaust system (104) of claim 5, wherein a structure formed by the entry section (204), the second bend (215), the middle section (206), the third bend (216), and the exit section (207) has a U-shaped profile.

10. The exhaust system (104) of claim 6, wherein a vertical distance between the entry section (204) and the exit section (207) is in a range between 100mm-150 mm.

11. The exhaust system (104) of claim 1, wherein the secondary catalytic converter assembly (205) includes an assembly sleeve (301), an upstream bend adapter member (303), a downstream bend adapter member (304), and a secondary catalytic converter (302).

12. The exhaust system (104) of claim 4, wherein the secondary catalytic converter assembly (205) is positioned in a range of 0% -60% of a true length of the exhaust gas passage pipe (201).

13. The exhaust system (104) of claim 4, wherein the secondary catalytic converter (302) covers at least 65% -70% of the intermediate section (206).

14. The draining system (104) of claim 4, wherein the assembly sleeve (301) is made of at least two sheet metal parts (301a, 301 b).

15. The exhaust system (104) of claim 13, wherein the assembly sleeve (301) surrounds the upstream bend adapter member (303) made of at least two sheet metal parts (303a, 303 b).

16. The exhaust system (104) according to claim 17, wherein the upstream bend adapter member (303) is connected at one end to the inlet section (204) of the exhaust gas passage pipe (201) and at the other end to the secondary catalytic converter (302).

17. The exhaust system (104) of claim 13, wherein the assembly sleeve (301) surrounds the downstream bend adapter member (304) made of at least two sheet metal parts (304a, 304 b).

18. The exhaust system (104) of claim 19, wherein the downstream bend adapter member (304) is connected at one end to the exit section (207) of the exhaust gas passage pipe (201) and at another end to the secondary catalytic converter (302).

19. The exhaust system (104) of claim 1, wherein the main catalytic converter (211) is disposed on the muffler inlet channel member (212) near the muffler inlet (209).

20. The exhaust system (104) of claim 1, wherein the main catalytic converter (211) is positioned in the muffler first portion (210) of the muffler (208).