DESC:TECHNICAL FIELD
[0001] The present subject matter generally relates to an emission control system for an internal combustion engine of a vehicle. More particularly but not exclusively, the present subject matter relates to a system for effectively monitoring the health of the emission control system of the vehicle.
BACKGROUND
[0002] An emission control system, or an exhaust system in vehicles, are employed to limit the discharge of noxious gases from an internal-combustion engine and other components. The exhaust pipe discharges burnt and unburnt hydrocarbons, carbon monoxide, oxides of nitrogen and sulfur etc. These pollutants have adverse effects on the environment and human health. Emissions from vehicles generally depends upon the air–fuel ratio. Various control techniques for limiting the effect of exhaust gas emissions are engine modifications, fuel pre-treatment, fuel additives, exhaust gas recirculation (EGR), an application of catalytic converters etc. A catalytic converter is a device that converts high toxic exhaust gas pollutants into less toxic gas pollutants. The catalytic converter is effective and consistent for reducing the noxious tailpipe emissions; therefore, it is widely used in the trucks, buses, cars, motorcycles and other construction equipments. In general, for effective burning of the emitted gases, it is disposed very near to an exhaust manifold of the engine which causes the catalytic converter to heat up quickly. Due to its exposure to the very hot exhaust gases, it reduces undesirable emissions during the engine warm-up period.
[0003] Typically, a honeycomb structured wash-coat is provided inside the catalytic converter which increases the contact surface area to get in touch with the exhaust gases to improve conversion effectiveness. The toxic gases CO, NO, and THC are converted into carbon dioxide, nitrogen, and water vapor respectively. During a lean burn cycle, excess oxygen is stored onto the surface of the catalytic converter whereas during a rich air-fuel mixture cycle, the catalytic converter releases stored oxygen for burning of the unburnt hydrocarbons. The stored oxygen is released in the reduction reaction and completes the conversion reaction.
[0004] Increasingly stringent regulations such as BS VI have limited the permissible levels for emissions. As such, vehicle manufacturers have developed various methods to reduce emissions while improving vehicle performance and fuel economy. To meet these requirements, it is necessary to monitor the performance of the catalyst converter, herein after called as converter. It is important to meet the onboard diagnostics II regulation (OBD-II) which states that an automobile manufacturer must be able to determine when the performance of the catalyst has deteriorated to the point that the vehicle is emitting more than the regulated limit of pollutants. Therefore, it is important to determine the health of the catalytic converter efficiently and accurately. Faulty catalytic converters can restrict the flow of exhaust, which negatively affects vehicle performance and fuel economy.

BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is described with reference to emission control system for an exemplary embodiment along with the accompanying drawings. The same numbers are used throughout the drawings to refer to similar features and components.
[0005] Fig 1 exemplarily illustrates a general assembly of emission control system in a vehicle layout in accordance with present invention.
[0006] Fig 2 exemplarily illustrates a section view of emission control system in the vehicle layout in accordance with an embodiment of the present invention.
[0007] Fig 3 exemplarily illustrates a graphical representation of the temperature at outlet of catalytic converters in accordance with an embodiment of the present invention.
DETAILED DESCRIPTION
[0008] Gases which are emitted from the engine are highly poisonous for the environment. Therefore, to curb the adversities of the emitted gases, various laws and regulations have been introduced, which mandates the automobile manufactures to limit the emission of poisonous gases. For automobile manufactures to adhere to such regulation, it is necessary to continuously monitor the health of emission control system of the vehicle.
[0009] As per known state of art, catalytic converters are used which enables catalytic reaction of the gas emitted from the engine. The catalytic reaction converts the toxic gases CO, NO, and THC into carbon dioxide, nitrogen, and water vapor respectively.
[00010] As per known state of art, a sensor sensing the oxygen density level of the emitted toxic gas emitted from the engine is installed in between the engine’s exhaust port and catalytic converter. This sensor is connected to an electronic control unit (ECU) through a wiring harness. The ECU reads the information sensed by the sensor to accurately update the air fuel ratio of the engine and to ensure the proper functioning of the engine. However, said sensor does not help in detecting health of the catalytic converter because the sensor detects the oxygen level of the emitted gas before the gas enters the catalytic converter. It fails to detect the oxygen level of the emitted gas once it is emits out of the catalytic converter. Hence, such known arrangement with a single sensor located before the inlet of the catalytic converter fails to accurately capture the oxygen density level of the emitted gases.
[00011] Moreover, as per another known state of art, two catalytic converters are used to enhance the catalytic reaction of the emitted gases such that said emitted gases undergoes redox reaction appropriately before being released into the environment. Generally, the second or secondary catalytic converter is located after the primary catalytic converter. The primary catalytic converter performs the function of emitting a chemical mixture that neutralizes any harmful toxin and the secondary catalytic converter performs the standard converter functions. Herein two catalytic converters are placed in the exhaust pipe with first oxygen density level detection sensor placed before the primary catalytic converter and the second oxygen density level detection sensor placed after the secondary catalytic converter. The toxic gas being released from the engine firstly passes through the first oxygen density level detection sensor to enter the primary catalytic converter. Such toxic gas then enters through the secondary catalytic converter, followed by the second oxygen density level detection sensor. The gas coming out of the secondary catalytic converter becomes hotter after it passes through the secondary catalytic converter. In said mechanism, it is not desirable to mount the second oxygen density level detection sensor at the rear end of said second catalytic converter, as due to excessive heat the sensors malfunctions, and provides inaccurate readings of oxygen level of the emitted gas. Therefore, it is a challenge for the automobile manufacturers to accurately and efficiently detect the proper functioning of the catalytic converter. It is yet another challenge to efficiently detect the oxygen level density of the emitted gas without affecting and altering the existing mechanism of the vehicle.
[00012] Moreover, typically, the afore-mentioned existing constructional arrangement faces the drawback that the efficiency of primary catalytic converter which performs the major function of emitting chemical mixture to neutralize the harmful toxin, which is located close to the engine manifold is hindered due to vast amount of heat generated by the engine. Secondary catalytic converter is not exposed to such vast amount of heat. Thereby, the efficiency of the entire emission control system is adversely affected due to the placement of primary catalytic converter close to the engine manifold, followed by the secondary catalytic converter located near the muffler assembly.
[00013] Further, another disadvantage of the existing arrangement is that there is no oxygen density level detection sensor present after the primary catalytic converter due to which accurate oxygen density levels in the toxic gases cannot be estimated post it passes through the primary catalytic converter. However, it is again not desirable to utilize three sensors, since the third oxygen density level detection sensor placed after the primary catalytic converter tends to provide inaccurate data due to being subjected to high temperatures.
[00014] Keeping note of the above, it is an object of the present invention to provide an emission control system for an internal combustion engine which can effectively and accurately monitor the health of the catalytic converters thereby ensuring appropriate treatment of toxic gases before being released into the environment. The present invention aims to achieve the objective without altering the existing layout of the vehicle, thereby making the system economical, which does not require explicit skill sets for servicing purpose. It is yet another objective of the present invention aims to improve the function of the sensor.
[00015] As per an embodiment of the present invention, an emission control system for an internal combustion engine comprises of an exhaust pipe; a primary catalytic converter; a secondary catalytic converter; and one or more sensors. The exhaust pipe extends from an exhaust manifold of said engine towards vehicle rear end. The primary catalytic converter and the secondary catalytic converter being able to perform catalytic reaction of gas emitted from said engine. The primary catalytic converter is operatively connected to the secondary catalytic converter whereby emitted gas enters the primary catalytic converter after passing through the secondary catalytic converter. The one or more sensors are configured to sense a predefined parameter of gas emitted from said engine wherein one of said one or more sensor are operatively disposed as a bridge between said primary catalytic converter and said secondary catalytic converter.
[00016] As per an embodiment of the present invention, said primary catalytic converter and said secondary catalytic converter being operatively connected through a bridge member, said one of said one or more sensor being operatively disposed on said bridge member.
[00017] As per an embodiment of the present invention, wherein said one or more sensor includes a primary sensor (206) and a secondary sensor.
[00018] As per an embodiment of the present invention, said predefined parameter being oxygen density level of said gas emitted from said engine.
[00019] As per an embodiment of the present invention, said primary sensor (206) being disposed downstream in the flow direction of said secondary catalyst converter and said primary catalyst converter in said exhaust pipe.
[00020] As per an embodiment of the present invention, said primary sensor (206) being mounted to a cylinder head of said engine.
[00021] As per an embodiment of the present invention, said primary sensor (206) being mounted to an exhaust pipe towards said engine direction.
[00022] As per an embodiment of the present invention, one end of said one or more sensors being operatively connected to an electronic control unit through a wiring harness.
[00023] As per an embodiment of the present invention, one of said one or more sensors being disposed at a predetermined distance from said engine.
[00024] As per an embodiment of the present invention, maximal of said pre-determined distance being 5 times of the diameter of said primary catalytic converter.
[00025] As per an embodiment of the present invention, said bridge element being a hollow pipe.
[00026] The present subject matter is further described with reference to the accompanying figures. It should be noted that the description and figures merely illustrate the principles of the present subject matter. Various arrangements may be devised that, although not explicitly described or shown herein, encompass the principles of the present subject matter. Moreover, all statements herein reciting principles, aspects, and examples of the present subject matter, as well as specific examples thereof, are intended to encompass equivalents thereof.
[00027] Accordingly, this description is to be considered as illustrative and is for the purpose of teaching those skilled in the art the manner of making and using various embodiments of the disclosure. It is to be understood that the forms of the disclosure herein shown and described are to be taken as representative embodiments. Equivalent elements, materials, processes, or steps may be substituted for those representatively illustrated and described herein. Moreover, certain features of the disclosure may be utilized independently of the use of other features, all as would be apparent to one skilled in the art after having the benefit of this description of the disclosure. Expressions such as “including”, “comprising”, “incorporating”, “consisting of”, “have”, “is” used to describe, and claim the present disclosure are intended to be construed in a non-exclusive manner, namely allowing for items, components or elements not explicitly described also to be present. Reference to the singular is also to be construed to relate to the plural.
[00028] Further, various embodiments disclosed herein are to be taken in the illustrative and explanatory sense and should in no way be construed as limiting of the present disclosure. All joinder references (e.g., attached, affixed, coupled, connected, etc.) are only used to aid the reader's understanding of the present disclosure, and may not create limitations, particularly as to the position, orientation, or use of the systems and/or methods disclosed herein. Therefore, joinder references, if any, are to be construed broadly. Moreover, such joinder references do not necessarily infer those two elements are directly connected to each other.
[00029] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[00030] Fig 1 exemplarily illustrates a general assembly of emission control system (104) in a vehicle layout in accordance with present invention. The vehicle assembly incudes a frame assembly (100). The frame assembly (100) comprises of plurality of frame members to support various elements of the vehicle. The frame assembly (100) is the structural member of the vehicle. The vehicle includes an internal combustion engine (102), herein after called as engine (102) to power the vehicle. The engine (102) has an inlet port (not shown), and an outlet port (not shown). The inlet port is connected to a carburettor (not shown), which mixes the air and fuel in appropriate ratio for proper functioning of the engine (102). For powering the wheels (not shown) of the vehicle, combustion of the air fuel takes place inside a combustion chamber (not shown) of the engine (102). After combustion, a huge number of unburnt gases are exhausted from an exhaust port of the engine (102). The unburnt gases released from the engine (102) are harmful for the environment, therefore a number of guidelines and regulation limits emission of pollutants. Therefore, an emission control system (104) in the vehicle enables treatment of the emitted gases from the engine (102) before being released to the environment. The emission control system (104), hereinafter called as system includes an exhaust pipe (105). The exhaust pipe (105) extends from exhaust port or exhaust manifold of the engine (102) towards rear side of the vehicle. The system (104) for treatment of the gases includes a secondary catalytic converter (200, shown in fig. 2), and a primary catalytic converter (202, shown in fig. 2). The emitted gas from exhaust pipe (105) enters the secondary catalytic converter (200), for first redox rection, and then the treated gas enters primary catalytic converter (202) for further treatment before being released into the environment. The inlet of the primary catalytic converter is operatively connected to outlet of the secondary catalytic converter. The connection between both the catalytic converters (200,202) are such that emitted gas enters the primary catalytic converter (202) after passing through said secondary catalytic converter (200).
[00031] Fig 2 exemplarily illustrates a section view of emission control system (104) in the vehicle layout in accordance with present invention. The emission control system (104) which includes one or more sensors (204,206) which are operatively connected to the secondary catalytic converter (200). The one or more sensors (204,206) senses a predetermined parameter of the emitted gas, for example the sensors sense the oxygen density of the emitted gas as per an aspect of the present invention. To ensure the health of the catalytic converter (200,202) it is important to check the quality of the emitted gas before the gas enters the catalytic converter and after the gas exists from the catalytic converter. If the oxygen density of the gas remains constant or there is insignificant change even after passing through, the catalytic converter (200,202), then the catalytic converter (200,202) is not functioning properly. In that scenario, an electronic control unit (not shown) sends a signal to the user, so that the user/rider can take appropriate action to ensure proper function of the emission system (104). Therefore, to accurately check the health of the catalytic converter (200,202) it is important for the one or more sensor (204,206) to function properly. The one or more sensor (204,206) includes a primary sensor (206) and a secondary sensor (204). It is a known fact that sensors tend to malfunction when they are exposed to high temperature. When the gas is emitted from the primary catalytic converter (202) it is at extremely high temperature. Therefore, it is a challenge to check the density of the emitted gas at the outlet of the primary catalytic converter (202) by a sensor. As per an aspect of the present invention, the primary sensor (206) is mounted between the secondary catalytic converter (200) and the primary catalytic converter, and a secondary sensor (204) is being disposed at the input of the secondary catalytic converter. More precisely, the primary sensor (206) is mounted at the output of the secondary catalytic converter (200) and the secondary sensor (204) is mounted at the input of the secondary catalytic converter (200). Such a positioning of the primary sensor (206) ensures that it is prevented from the excessive heat which is being generated at the outlet of the secondary catalytic converter (200). Since theprimary catalytic converter (202) is disposed after the secondary catalytic converter (200) in the vehicle rear direction, therefore, the secondary catalytic converter (200) is more prone to damages and deterioration due to the excessive heat generated from the engine as it is closer to the engine outlet. The primary catalytic converter (202) is not exposed to the excessive heat generated by the engine, thereby improving the life of the primary catalytic converter (202).
[00032] The secondary catalytic converter (200) is connected to the primary catalytic converter (202) by a bridge member. The bridge member is a hollow pipe, which supports the primary sensor (206). As per an embodiment of the present invention, the secondary sensor (204) can be mounted at the cylinder head of the engine (102). The one or more sensor (204,206) is connected to the electronic control unit (ECU) (not shown) through a wiring harness (204a,206a). The ECU sends an error signal to the rider in case the one or more sensor (204,206) reading at the inlet and outlet of the primary catalytic converter (200) are same or substantially indifferent. The distance of the primary sensor (206) from the engine (102) is at a predetermined distance. For example, the maximal distance between the primary sensor (206) and the engine (102) is 5 times the diameter of the secondary catalytic converter (200), to ensure that beyond the maximal distance the sensor again gets exposed to the high temperature which can interrupt the functioning of sensor.
[00033] Fig. 3 exemplarily illustrates a graphical representation of the temperature at said catalytic converters in accordance with present invention. The graph depicts that the temperature experienced by the one or more sensor (204,206) at the outlet of the primary catalytic converter (202) is extremely high than the temperature at the outlet of the secondary catalytic converter (200). T1 refers to the temperature of o2 sensor placed after secondary catalytic converter as per prior art. T1 is ~320 degrees. Existing arrangement: first sensor? primary catalytic converter secondary catalytic converter second sensor (here t1 refers to temperature of second sensor). T2 is the temperature of 02 sensor placed in between the secondary and primary catalytic converter. T2 is ~280 degrees. Thus, a temperature difference of about ~40 degree Celsius is achieved.
[00034] 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 light of the above disclosure. Therefore, within the scope of claims of the present subject matter, the present disclosure may be practiced other than as specifically described.

List of Reference numerals
100: Frame assembly
102: Internal combustion engine
104: Emission control system
105: Exhaust pipe
200,202: catalytic converters
204,206: one or more sensors
204a, 206a: wiring harness
,CLAIMS:We claim:
1. An emission control system (104) for an internal combustion engine (102) of a vehicle, said emission control system (104) comprising:
an exhaust pipe (105); said exhaust pipe (105) extends from an exhaust manifold of said internal combustion engine (102) towards said vehicle rear end;
a secondary catalytic converter (200);
a primary catalytic converter (202); said primary catalytic converter (202) and said secondary catalytic converter (200) being able to perform catalytic reaction on gas emitted from said internal combustion engine (102); and
one or more sensors (204,206); said one or more sensors (204,206) being configured to monitor a predefined parameter of gas emitted from said internal combustion engine (102),
wherein an inlet of said primary catalytic converter (202) being operatively connected to an outlet of said secondary catalytic converter (200) whereby emitted gas enters said primary catalytic converter (202) after passing through said secondary catalytic converter (200); and
wherein one of said one or more sensors (204, 206) being operatively disposed between said outlet of said secondary catalytic converter (200) and said inlet of said primary catalytic converter (202) to prevent said one or more sensors (204, 206) from being damaged due to excessive heat generated from said internal combustion engine (202) and to effectively monitor the health of said emission control system (400) based on said predefined parameter of emitted gas from said internal combustion engine (102).

2. The emission control system (104) as claimed in claim 1, wherein said primary catalytic converter (202) and said secondary catalytic converter (200) being operatively connected through a bridge member, said one of said one or more sensor being operatively disposed on said bridge member.
3. The emission control system (104) as claimed in claim 1, wherein said one or more sensor includes a primary sensor (206) and a secondary sensor (204).
4. The emission control system (104) as claimed in claim 1, wherein said predefined parameter being oxygen density level of said gas emitted from said internal combustion engine (102).
5. The emission control system (104) as claimed in claim 1, wherein said primary sensor (206) being disposed downstream in the flow direction of said secondary catalytic converter (200) and said primary catalytic converter (202) in said exhaust pipe (105).
6. The emission control system (104) as claimed in claim 3, wherein said secondary sensor (204) being mounted to a cylinder head of said internal combustion engine (102).
7. The emission control system (104) as claimed in claim 3, wherein said secondary sensor (204) being mounted at inlet of said secondary catalytic converter (200) in said exhaust pipe (105).
8. The emission control system (104) as claimed in claim 1, wherein one end of said one or more sensor (204,206) being operatively connected to an electronic control unit through a wiring harness (204a,206a).
9. The emission control system (104) as claimed in claim 1, wherein one of said one or more sensor (204,206) being disposed at a predetermined distance from said internal combustion engine (102).
10. The emission control system (104) as claimed in claim 9, wherein maximal of said predetermined distance being 5 times of the diameter of said secondary catalytic converter (200).
11. The emission control system (104) as claimed in claim 1, wherein said bridge element being a hollow pipe