Claims:We claim:
1. A controller (120) to reduce pollutants in an exhaust emission of a vehicle (100), said controller (120) adapted to:
regulate opening of an electrical valve (106) of an air injection system (118) in an exhaust conduit (102), to supply air inside said exhaust conduit (102), and
drive a fuel injector 130 in a fuel injection pattern, wherein said fuel injection pattern is any one selected from at least two different varying rich air-fuel mixtures inside a cylinder of an engine, selectively, to reduce emissions in said exhaust conduit (102) in presence of said supplied air.
2. The controller (120) as claimed in claim 1, wherein said fuel injector 130 is driven in said fuel injection pattern to obtain a profile of an air-fuel ratio in said exhaust conduit, selected from any one of a leaner profile (202), a richer profile (206) and a near stoichiometric profile (204).
3. The controller (120) as claimed in claim 1, wherein said fuel injector 130 is driven in said pattern after a catalyst light-off temperature is attained.
4. The controller (120) as claimed in claim 1, wherein said fuel injector 130 is driven in said pattern before a catalyst light-off temperature is attained.
5. The controller (120) as claimed in claim 1, drives said fuel injector 130 based on input signals received from an engine speed sensor (126), a throttle position sensor (128), and a lambda sensor (124).
6. A method for reducing pollutants in exhaust emission of a vehicle (100), said method comprising the steps of:
regulating opening of an electrical valve (106) of an air injection system (118) in an exhaust conduit (102), for supplying air inside said exhaust conduit (102), and
driving a fuel injector 130 in a fuel injection pattern, wherein said fuel injection pattern is any one selected from at least two different varying rich air-fuel mixtures inside a cylinder of an engine, selectively, reducing emissions in said exhaust conduit (102) in presence of said supplied air.
7. The method as claimed in claim 6, wherein said fuel injector 130 is driven in said fuel injection pattern for obtaining a profile of an air-fuel ratio in said exhaust conduit, selected from any one of a leaner profile (202), a richer profile (206) and a near stoichiometric profile (204).
8. The method as claimed in claim 6, wherein driving said fuel injector 130 is performed after a catalyst light-off temperature is attained.
9. The method as claimed in claim 6, wherein driving said fuel injector 130 is performed before a catalyst light-off temperature is attained.
10. The method as claimed in claim 6, wherein driving said fuel injector 130 is done based on input signals received from an engine speed sensor (126), a throttle position sensor (128), and a lambda sensor (124).

, Description:Field of the invention:
[0001] The present invention relates to a controller and a method to reduce exhaust emission pollutants in a vehicle.

Background of the invention:
[0002] According to a patent US3986352, a closed loop fuel control using air injection in open loop modes is disclosed. A fuel control for an engine is normally operated closed loop with a feedback signal from an air-fuel ratio sensor in the engine exhaust. However, during idle, wide open throttle and engine warm up operating modes, the closed loop control is cut out and the engine is run rich with air injected into the exhaust system to reduce carbon monoxide and hydrocarbon emissions.

Brief description of the accompanying drawings:
[0003] An embodiment of the disclosure is described with reference to the following accompanying drawing,
[0004] Fig. 1 illustrates a vehicle with a controller to reduce pollutants in an exhaust emission, according to an embodiment of the present invention;
[0005] Fig. 2 illustrates patterns and profiles of air-fuel ratio, according to an embodiment of the present invention, and
[0006] Fig. 3 illustrates a method for reducing pollutants in the exhaust emission, according to the present invention.

Detailed description of the embodiments:
[0007] Fig. 1 illustrates a vehicle with a controller to reduce pollutants in an exhaust emission, according to an embodiment of the present invention The vehicle 100 is a conventional vehicle 100 comprising engine 114 with single or multiple cylinders, a throttle body, a throttle position sensor (TPS) 128, a fuel injector 130, an air injection system 118 comprising a tube 104 connecting an air box (not shown) of a intake conduit 116 to an exhaust conduit 102, an electrical valve 106 and a reed valve/ one way valve 110, and an Exhaust Treatment Unit (ETU) 108 comprising a three-way catalyst, or other types of catalyst. A lambda sensor 124 is placed after the entry port of air injection system 118. The components of the air injection system 118 are encircled with a dotted line. The tube 104 receives air from air box as it is filtered, otherwise the inlet for the tube 104 is taken directly from the atmosphere without the air box, such as at the interface of the tube 104 and the exhaust conduit 102. Only few components of the vehicle 100 are listed for the purpose of explanation and clarity, and the same must not be understood in limiting sense.
[0008] 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, only when the electrical valve 106 is open. This is referred to as aspirated air injection due to the negative pressure pulses in the exhaust conduit 102. In other embodiment, a pump is used to supply air to air injection system 118. The term lambda and air-fuel ratio correspond to same meaning and may be used interchangeably.
[0009] The vehicle 100 is provided with the air injection system 118 in the exhaust conduit 102. The air injection in the exhaust conduit 102 is performed to reduce pollutants in the exhaust emission. 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 pollutants or emissions such as Total Hydro Carbon (THC), Carbon Monoxide (CO) and oxides of Nitrogen (NOx). During the initial time of the operation of the engine 114, the release of THC, CO are more, thus the fresh air reacts with THC and CO in this hot environment and oxidize to CO2 and H2O.
[0010] In accordance to an embodiment of the present invention, the controller 120 is provided to reduce exhaust emissions from the vehicle 100. The controller 120 is adapted to regulate opening of an electrical valve 106 of the air injection system 118 in the exhaust conduit 102. The air injection system 118 supplies air inside the exhaust conduit 102. The “regulate opening of the electrical valve 106” corresponds to an amount of opening of cross-sectional area of the tube 104 for the flow of air, such as completely open, half open or partially open etc. The controller 120 then drives a fuel injector 130 in a fuel injection pattern. The fuel injection pattern is any one selected from at least two different varying fuel injection patterns which causes a corresponding rich air-fuel mixtures inside a cylinder of the engine 114. The controller 120 selectively drives the fuel injector 130 in any one fuel injection pattern to reduce emissions in the exhaust gas in presence of the supplied air in the exhaust conduit 102. The controller 120 controls fuel injection to perform combustion of rich air-fuel mixture. After combustion, the exhaust gas also has a lambda or air-fuel ratio less than 1, i.e. the combustion of rich air-fuel mixture results in an exhaust gas with rich air fuel ratio. The exhaust gas, in the presence of air in the exhaust conduit 102, undergoes exothermic reactions thereby further reducing the emissions. Based on the pattern of fuel injection selected by the controller 120, a corresponding pollutant in the emission is reduced.

[0011] The controller 120 is a control unit comprising an Input/ Output interface, a processor, a memory unit 122 such as a Random Access Memory (RAM), a Read Only Memory (ROM), a clock, an Analog-to-Digital (ADC) convertor 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. The memory unit 122 stores the at least two fuel injection patterns, along with conditions of switching between the at least two fuel injection patterns.
[0012] Fig. 2 illustrates patterns and profiles of air-fuel ratio, according to an embodiment of the present invention. The graph shows an air-fuel ratio values inside the cylinder of the engine 114 and in the exhaust conduit 102. The air-fuel ratio is represented by ?. The controller 120 is adapted to inject more fuel than the air to create a rich air-fuel mixture inside the cylinder of the engine 114. In accordance to an embodiment of the present invention, the fuel injector 130 is driven to create at least two different rich air-fuel mixtures to obtain a profile of an air-fuel ratio in the exhaust conduit 102 selected from any one of a leaner profile 202, a richer profile 206 and a near stoichiometric profile 204. The leaner profile 202 signifies keeping the lean phase or time more than the rich phase time in the exhaust conduit 102. The controller 120 drives the fuel injector 130 based on input signals received for engine speed from an engine speed sensor 126, a load demand from a throttle position sensor 128 and an air-fuel ratio in the exhaust conduit 102 from a lambda sensor 124.
[0013] The controller 120 either directly or in communication with an Engine Control Unit (ECU) of the vehicle 100, reduces the emission. Alternatively, the ECU is the controller 120. Based on the mass or volume of air entered in the cylinder, a quantity of fuel to be injected is determined by the controller 120. The controller 120 drives the fuel injector 130 and injects the determined fuel to form a first rich air-fuel mixture inside the cylinder of the engine 114. The first rich air-fuel mixture is maintained below a near stoichiometric ratio of value 1. After combustion, the in-cylinder air-fuel ratio is rich shown by first curve 208, therefore the air-fuel ratio of the exhaust gas is also rich. But, for conversion of THC and CO, a lean air-fuel ratio is needed. The open electrical valve 106 supplies air to the exhaust conduit 102. The excess air and the exhaust gas with rich air-fuel ratio undergoes oxidation and/or reduction reactions thus resulting in exhaust gas with leaner air-fuel ratio or the leaner profile 202. The leaner air-fuel ratio is sensed and maintained by the controller 120 through the lambda sensor 124. The controller 120 varies the pattern of fuel injection based on the detected lambda value to maintain the leaner profile 202. The pattern is varied by controlling the duty cycle, frequency of operation of the fuel injector 130.
[0014] Now, to convert, the NOx, the exhaust gas with rich air-fuel ratio is required. Now, without regulating the electrical valve 106, the controller 120 determines the fuel quantity, and injects the determined fuel with an injection pattern such that, a second air-fuel mixture is formed inside the cylinder of the engine 114. The second air-fuel mixture is chosen in a manner that the in-cylinder air-fuel ratio shown by the curve 210 is obtained. The curve 210 is lower than the curve 208 but are within the range of rich air-fuel ratio, signifying the fuel injection pattern is altered. The second air-fuel mixture is though richer but different than the first air-fuel mixture. In the presence of the supplied air in the exhaust conduit 102, a richer air-fuel ratio or richer profile 206 is obtained, and the same is maintained by using the feedback from the lambda sensor 124. The richer profile 202 signifies keeping the rich phase or time more than the lean phase in the exhaust conduit 102. In the leaner profile 202, the reduction of THC and CO emissions are more, and NOx reductions are less, whereas in the richer profile 206, the reduction of NOx is more, and THC and CO reductions are less.
[0015] In other words, the controller 120 shifts the curve 208 or 210 to 202 or 204 respectively based on the tuning or control of fuel injection pattern, in the presence of air injection system 118. Though the curves and profiles are shown at a specific distance from each other (not to the scale), the same must not be understood in limiting manner, and is only for explanation.
[0016] The controller 120 is able to maintain duration of lean and rich phase and reduces the emission thereby. The controller 120 while reducing emissions, also maintains the temperature of the ETU 108 for effective conversion of the THC, CO and NOx.
[0017] A working example is explained but must not be understood in limiting manner. When the engine 114 is cold, the THC emissions are high. But once the engine 114 is warm, the THC output reduces. Before catalyst reaches the light-off temperature, the controller 120 injects fuel in manner to run leaner profile 202 in the exhaust conduit 102. After the catalyst light-off temperature is attained, the engine 114 is heated up, then the engine out NOx emissions starts to increase and THC emissions reduces. In this case, the controller 120 changes the fuel injection pattern to obtain a richer profile 206 in the exhaust conduit 102. Here, the conditions of switching from leaner profile 202 to the richer profile 206 is disclosed. Other conditions may be used for the switching without departing from the scope of the invention.
[0018] The controller 120 is applied to the vehicle 100 comprising 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.
[0019] In accordance to an embodiment of the present invention, the controller 120 is adapted to drive the fuel injector 130 or control fuel injection after a catalyst light-off temperature is attained. Alternatively, the controller 120 is adapted to drive the fuel injector 130 or control fuel injection before the catalyst light-off temperature is attained or till the catalyst light-off temperature is attained. The catalyst light-off temperature is attained in open loop (or closed loop), i.e. without or with taking feedback from the lambda sensor 124. The catalyst light-off temperature is obtained by the exothermic reactions in the exhaust conduit 102 due to the supply of air from the air injection system 118.
[0020] Fig. 3 illustrates a method for reducing pollutants in the exhaust emission, according to the present invention. The method comprises the steps of, a step 302 comprising regulating opening of the electrical valve 106 of the air injection system 118 in the exhaust conduit 102, for supplying air inside the exhaust conduit 102. A next step 304 comprises driving the fuel injector 130 in a fuel injection pattern. The fuel injection pattern is any one selected from at least two different fuel injection patterns which causes or forms different varying rich air-fuel mixtures inside the cylinder of the engine 114. The fuel injection is done selectively for reducing emissions in the exhaust conduit 102 in presence of the supplied air. The controller 120 drives the fuel injector 130 and controls the same in terms of duty cycle/ frequency for controlling the fuel injection pattern.
[0021] The fuel injector 130 is driven to get at least two different rich air-fuel mixtures for obtaining the profile of the air-fuel ratio in the exhaust conduit 102, selected from any one of a leaner profile 202, a richer profile 206 and a near stoichiometric profile 204.
[0022] The driving of the fuel injector 130 is done based on input signals received from an engine speed sensor 126, a throttle position sensor 128 and a lambda sensor 124.
[0023] The method step comprising driving the fuel injector 130 or controlling fuel injection is performed after a catalyst light-off temperature is obtained/ attained. Alternatively, driving the fuel injector 130 or controlling fuel injection is performed before the catalyst light-off temperature is obtained/ attained or till catalyst light-off temperature is attained. The catalyst light-off temperature is obtained in open loop manner, i.e. without taking inputs from a lambda sensor 124 or in closed loop manner.
[0024] Due to the air injection system 118, the controller 120 operates engine 114 with rich in-cylinder air-fuel ratio, such that the engine out NOx are low. The rich combustion also provides better combustion stability and drive feel. Further, in the presence of the excess oxygen supplied by the air injection system 118, the exhaust lambda is toggled between a narrow range of lambda values such as 0.97 to 1.03 (values are only for example). Thus, there is same conversion of THC, CO and NOx when compared to conventional operation of the engine 114, but since the engine out NOx is low, there is even lesser tail pipe NOx. The controller 120 enables running the leaner profile 202 to get better conversion for THC and CO as well.
[0025] In the present invention, the controller 120 switches the fueling pattern to reduce emissions. With the air injection system 118, the controller 120 is able to run with lambda=1 in exhaust and rich in-side the cylinder. The controller 120 provides a flexibility in the switching pattern of the fuel injection. Based on the fuel injection pattern selected, a lean profile 202 is obtained which boosts THC and CO conversion or a richer profile 206 is obtained to boost NOx conversion and increase the temperature in the catalyst. Further, since there is higher THC released by the engine 114 which is burnt by the air supplied by the air injection system 118 which releases heat to the exhaust conduit 102 which further boosts all conversion reaction.
[0026] 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.