Field of the invention:
The present invention relates to an exhaust treatment unit of a vehicle and to a method for maintaining temperature of the same.
Background of the invention:
According to an Indian patent application 201741018720, a modified exhaust system for automobiles is disclosed. The Engine Exhaust system is the main component in discharging the exhaust gases to the atmosphere and helps in reducing the emissions and noise from the engine. This project aims in improving the life of the exhaust system by modifying the catalytic converters chamber and also to increase the efficiency of oxidation catalyst from the starting time of vehicle. For increasing the life of catalytic converter, it should be cleaned periodically. Here, we pump the fresh air at sufficient temperature to increase the efficiency of oxidation catalyst during starting of the vehicle. An electric heater is wound around it to attain the sufficient conversion temperature, so that, the reduction of emission is possible from the starting time of the engine itself. The electric heater will turn on, when all the electric components inside the vehicle is turned on. The electric heater automatically cuts off the process, when the catalyst reaches the sufficient conversion temperature with the help of temperature sensor. This project is a basic prototype of the future advancement of the vehicles exhaust system.
Brief description of the accompanying drawings:
An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0004] Fig. 1 illustrates an Exhaust Treatment Unit (ETU) of a vehicle, according to an embodiment of the present invention, and
[0005] Fig. 2 illustrates a method for heating the ETU of the vehicle, according to the present invention.
Detailed description of the embodiments:

[0006] Fig. 1 illustrates an Exhaust Treatment Unit (ETU) of a vehicle, according to an embodiment of the present invention. The ETU 108 is provided in an exhaust conduit 102 of the vehicle 100. The vehicle 100 comprises Air Injection System 118 which controls flow of air into an exhaust conduit 102. The ETU 108 is characterized by positioning in the exhaust conduit 102. The ETU 108 is positioned at a distance from an exhaust port of the engine 114. The distance is at least twenty times the diameter of the exhaust port. The distance is represented by the portion 112 of the exhaust conduit 102. The exhaust conduit 102 starts from the exhaust port of the engine 114 to the point where the exhaust gas is released to the atmosphere, including the muffler/ silencer.
[0007] The ETU 108 may comprises at least one catalyst. The at least one catalyst of the ETU 108 is heated using the air injection system 118 during operation of the engine 114. The ETU 108 is maintained above a threshold temperature by the air injection system 118. A controller 120 controls the air injection system 118 when a drop in temperature of the ETU 108 is detected.
[0008] The (drop in) temperature is detected by at least one of a temperature sensor 128 and an exhaust temperature model. The exhaust temperature model is a function of at least an engine speed, a throttle position, a lambda value and an ignition angle of the combustion. The engine speed is measure from a crankshaft position sensor 124. The throttle position or the load demand is detected by a throttle position sensor 126. The lambda valve is calibrated value accessed from an Engine Control Unit (ECU) of the vehicle 100. Alternatively, a controller 120 is provided with the same data as a map or table stored in a memory unit 122.
[0009] The Air Injection System 118 comprises a tube 104 with a reed valve 110 and an electrical valve 106. The tube 104 is connected to the exhaust conduit 102 near the exhaust port of the engine 114. The reed valve 110 allows flow of fluid in only one direction, i.e. the air flows into the exhaust conduit 102 and restricts the flow of exhaust gas to the intake conduit 116. Further, the reed valve 110 operates based on the pressure difference between the exhaust gas and the air in the air box

without any pump. This is referred to as aspirated air injection due to the negative pressure pulses in the exhaust conduit 102.
[0010] The vehicle 100 is provided with the controller 120 to control air injection in the exhaust conduit 102. The air injection in the exhaust conduit 102 is performed to reduce emissions/ pollutants. The air flows inside the tube 104 from the air box through the electrical valve 106 and the reed valve 110 to the exhaust conduit 102. The air injection in the exhaust conduit 102 is performed to reduce emissions such as Total Hydro Carbon (THC), Carbon Monoxide (CO) and oxides of Nitrogen (NOx).
[0011] The controller 120 is control unit comprising an Input/ Output interface, a processor, the memory unit 122 such as a Random Access Memory (RAM), a Read Only Memory (ROM), a clock, an Analog-to-Digital (ADC) converter and other components which are all interconnected by communication channels called bus. The controller 120 is same as the Engine Control Unit (ECU) of the vehicle 100 or is completely separate and independent from the ECU. If the controller 120 is independent/ separate from the ECU, then the controller 120 accesses the required information from the memory unit 122 of the ECU, to avoid redundancy.
[0012] In accordance to yet another embodiment of the present invention, the controller 120 increases and maintains the catalyst at the threshold temperature as and when a drop in temperature of the catalyst is detected. Once the catalyst has attained light-off, temperature the concentration of oxygen at the catalyst signifies which constituent out of THC, CO and NOx is converted more efficiently. A narrow/wide band lambda sensor is used to initiate switching in the oxygen concentration between rich and lean cycles such that all the THC, CO and NOx are efficiently converted within the catalyst to CO2, H2O and N2. The ratio of THC:CO:NOx is mandated by the engine out emissions at a particular load and engine speed. The controller 120 is adapted to perform a specific lambda switching strategies for a particular load and engine speed.

[0013] The catalyst ensures maximum conversion when the temperature is above a typical valve such as 400°C. But if the temperature drops below a threshold valve/temperature, the exhaust purification efficiency drops drastically. Thus, the controller 120 is adapted to maintain the catalyst temperature by the use of exhaust temperature model to detect the temperature loss at the catalyst and realize that the catalyst has lost the conducive temperature. Alternatively, the controller 120 use a temperature sensor 128 at the catalyst.
[0014] When the controller 120 detects a loss in temperature, the controller 120 actuates/opens the electrical valve 106 of the air injection to purge fresh air into the exhaust conduit 102. In addition, the controller 120 operates the engine 114 with richer air-fuel ratio such that there is a sizeable amount of THC and CO released. The fresh air reacts with the excess THC and CO, oxidizing it to CO2 and H2O. Since the reactions are exothermic, there is a considerable amount of heat released into the exhaust conduit 102. The excess heat released reaches to the catalyst and ensures the catalyst is maintained at the required threshold temperatures.
[0015] In a case that the catalyst is still not at the required temperatures, then catalyst heating is engaged along with the air injection in the exhaust conduit 102. The catalyst heating signifies retardation of ignition angles within the engine 114 cylinders to ensure more energy is released to boost THC oxidation rate along the exhaust conduit 102. Thus, the controller 120 ensures combined effect of air injection and catalyst heating to maintain the catalyst at the required temperatures.
[0016] The controller 120 is applicable to or configured for the vehicle 100 comprising any one of a carburetor based fuel delivery system and an electronic fuel injection system. Further, the vehicle 100 is any one of a two wheeler such as motorcycle, moped, scooter, three wheeler such as auto-rickshaws, a four wheeler such as car and the like.

[0017] Fig. 2 illustrates a method for heating the ETU of the vehicle, according to the present invention. The method comprises a step 202 comprising detecting a temperature of the catalyst of the ETU 108. The temperature is detected by monitoring parameters comprising engine speed, throttle position, lambda value and ignition angle through an exhaust temperature model. A step 204 comprises increasing and maintaining temperature of the catalyst above a threshold temperature by burning enriched air-fuel ratio in the engine 114 when the temperature is detected to be below the threshold temperature. Due to step 204, more heat released in the exhaust conduit 102 which assists/ aids in increasing the temperature of the catalyst. A next step 206 is performed comprising operating air injection system 118 for selectively introducing air into exhaust conduit 102 of the vehicle 100.
[0018] The step 204 and 206 may be started simultaneously. Alternatively, the step 206 is performed prior to step 204. Even after the step 204 and 206, if the temperature of the catalyst is not increased, then a step 208 is performed comprising retarding ignition angle of the combustion to release more THC and CO to exhaust, thereby reacting with fresh air and releasing even more heat. This step ensures that sufficient heat is provide to the catalyst of the ETU 108 to maintain the temperature above the threshold temperature.
[0019] The temperature of the ETU 108 is maintained by operating the Air Inj ection System 118 for a configuration comprising specifically positioned ETU 108. The catalyst of the ETU 108 is positioned at a distance, of at least twenty times the diameter of the exhaust port, from the exhaust port.
[0020] The present invention ensures sufficient heat maintained to keep the catalyst of the ETU 108 further away from the exhaust port, in contrast to conventional way of positioning. At this distance the exhaust back pressure is reduced as well as durability of the catalyst is improved since there is very little thermal fluctuations at a farther distance from the exhaust port.

[0021] It should be understood that embodiments explained in the description above are only illustrative and do not limit the scope of this invention. Many such embodiments and other modifications and changes in the embodiment explained in the description are envisaged. The scope of the invention is only limited by the scope of the claims.

CLAIMS We claim:
1. An exhaust treatment unit (ETU) (108) in an exhaust conduit (102) of a
vehicle (100), said vehicle comprises an air injection system (118) which
controls flow of air into said exhaust conduit (102), characterized in that,
said ETU (108) is positioned at a distance from an exhaust port of said engine (114), said distance is at least twenty times the diameter of said exhaust port.
2. The ETU (108) as claimed in claim 1, wherein at least one catalyst of said ETU (108) is heated using said air injection system (118) during operation of said engine (114).
3. The ETU (108) as claimed in claim 1, wherein said ETU (108) is maintained above a threshold temperature by said air injection system (118).
4. The ETU (108) as claimed in claim 3, wherein a controller (120) controls said air injection system (118) when a drop in temperature below said threshold temperature of said ETU (108) is detected.
5. The ETU (108) as claimed in claim 4, wherein said drop in temperature is detected by at least one of a temperature sensor (128) and an exhaust temperature model.
6. The ETU (108) as claimed in claim 5, wherein said exhaust temperature model is a function of at least an engine speed, a throttle position, a lambda value and an ignition angle of the combustion.
7. The ETU (108) as claimed in claim 1, wherein said vehicle (100) comprises any one of a carburetor based fuel delivery system and an electronic fuel injection system.