Claims:We claim:
1. A controller (112) to control air injection in an exhaust conduit (104) of a vehicle (100), said controller (112) adapted to:
- measure a temperature of an engine (110) by a temperature sensor (117), and
- regulate opening of an electrical valve (106) based on measured temperature of said engine (110), to allow air flow into said exhaust conduit (104) upstream of a catalyst of an Exhaust Treatment Unit (ETU) (114).

2. The controller (112) as claimed in claim 1, wherein opening of said electrical valve (106) is regulated when said measured temperature is below said threshold temperature.

3. The controller (112) as claimed in claim 1, wherein opening of said electrical valve (106) is regulated until a light-off temperature of said catalyst is attained.

4. The controller (112) as claimed in claim 1, wherein said regulate opening of said electrical valve (106) comprises operating said electrical valve (106) in open position and close position to switch an air-fuel ratio of exhaust gas between a rich phase and a lean phase, while said catalyst is above a light-off temperature.

5. The controller (112) as claimed in claim 1, comprises retards ignition angle to increase temperature of exhaust gas to aid in early activation of said catalyst.

6. The controller (112) as claimed in claim 1, maintains temperature of said catalyst above a minimum temperature by at least one of enrichment of air-fuel mixture inside a cylinder of said engine (110) and retardation of ignition angle inside said engine (110).

7. The controller (112) 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.

8. A method for controlling air injection into an exhaust conduit (104) of a vehicle (100), said method comprising the steps of:
- measuring temperature of an engine (110) by a temperature sensor (117), and
- regulating opening of an electrical valve (106) based on said measured temperature of said engine (110) to introduce air into an exhaust conduit (104), upstream of a catalyst of an Exhaust Treatment Unit (ETU) (114).

9. The method as claimed in claim 8, wherein regulating opening of said electrical valve (106) is performed when said measured temperature of said engine (110) is detected below a threshold temperature.

10. The method as claimed in claim 8, wherein opening of said electrical valve (106) is regulated until a light-off temperature of said catalyst is attained.

11. The method as claimed in claim 8, wherein regulating opening of said electrical valve (106) comprises operating said electrical valve (106) to open position and close position for switching an air-fuel ratio of an exhaust gas between rich phase and lean phase, after said light-off temperature is attained.

12. The method as claimed in claim 8, further comprises retarding ignition for increasing temperature of exhaust gases, to aid in early activation of said catalyst.

13. The method as claimed in claim 8, further comprises maintaining temperature of said catalyst above a light-off temperature by at least one of enriching air-fuel mixture inside a cylinder of said engine (110) and retarding ignition angle inside said engine (110).
, Description:Field of the invention:
[0001] The present invention relates to a controller to operate Air Injection system in a vehicle.

Background of the invention:
[0002] According to a patent US2010083935, a control system for internal combustion engine is disclosed. The control system for a spark ignition internal combustion engine, when a catalyst is not sufficiently active, the ignition timing is advanced Retarded to be earlier than MBT to decrease the quantity of hydrocarbons (HC) discharged from the internal combustion engine, and oxygen is supplied to the exhaust gas upstream of the catalyst to thereby oxidize carbon monoxide (CO) and Hydrocarbon (HC) discharged from the internal combustion engine. According to this invention, exhaust emissions emitted before activation of the exhaust gas purification apparatus can be decreased as much as possible, and early activation of the catalyst can be achieved by making use of heat generated by oxidation reaction of carbon monoxide (CO) and Hydrocarbon (HC).

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 control air injection in exhaust conduit, according to an embodiment of the present invention, and
[0005] Fig. 2 illustrates a method for controlling air injection in the exhaust conduit, according to the present invention.

Detailed description of the embodiments:
[0006] Fig. 1 illustrates a vehicle with a controller to control air injection in exhaust conduit, according to an embodiment of the present invention. The vehicle 100 is a conventional vehicle 100 comprising engine 110 with single or multiple cylinders, a throttle body, a throttle position sensor (TPS) 116, a fuel injector ( or a carburetor), an air injection assembly for an exhaust conduit 104 comprising a tube 102 connecting an air box (not shown) of a intake conduit, an electrical valve 106 and a reed valve/ one way valve 108, and an Exhaust Treatment Unit (ETU) 114 comprising a three-way catalyst, or other types of catalyst. 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. The tube 102 receives air from the air box as it is filtered, otherwise the inlet for the tube 102 is taken directly from the atmosphere without the air box, such as at the interface of the tube 102 and the exhaust conduit 104. The air injection is also known as Secondary Air Injection (SAI).
[0007] The reed valve 108 allows flow of fluid in only one direction, i.e. the air flows into the exhaust conduit 104 and restricts the flow of exhaust gas to the intake conduit. Further, the reed valve 108 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 104.
[0008] The vehicle 100 is provided with a controller 112 to control air injection in the exhaust conduit 104. The air injection in the exhaust conduit 104 is performed to reduce emissions/ pollutants. The air flows inside the tube 102 from the air box through the electrical valve 106 and the reed valve 108 to the exhaust conduit 104. The air injection in the exhaust conduit 104 is performed to reduce 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 110, the release of THC, CO are more, thus the fresh air reacts with THC and CO in this hot environment in the exhaust gas and oxidize to CO2 and H2O.
[0009] In accordance to an embodiment of the present invention, a controller 112 to control air injection in the exhaust conduit 104 of the vehicle 100 is disclosed. The controller 112 is adapted to measure temperature of the engine 110 by an engine temperature sensor 117. Alternatively, a time difference between last engine shutdown and the current engine start is compared with a threshold time and accordingly the electrical valve 106 is operated by the controller 112. The threshold time is stored in a memory unit 120 of the controller 112. The controller 112 then regulates opening of the electrical valve 106 based on the measured temperature of the engine 110 to allow fresh air into the exhaust conduit 104 upstream of the catalyst of the ETU 114.
[0010] The temperature of the engine 110 or the time difference is measured to determine a cold phase of the engine 110. The cold phase signifies a cold start or starting the engine 110 in cold or ambient environment after a long time of shut down.
[0011] In one embodiment, the controller 112 regulates opening of the electrical valve 106 corresponds to controlling a degree of opening a passage in the tube 102. For example: the passage is partially or half or completely open or any other possible openings. In one embodiment, the electrical valve 106 is completely opened, i.e. the electrical valve 106 in the tube 102 is regulated to an open position to allow fresh air into the exhaust conduit 104 upstream of the catalyst of the ETU 114, when the engine temperature is detected to be below a threshold temperature.

[0012] The electrical valve 106 is any valve which can be controlled by supplying electricity such as solenoid valve, a linear actuator, a steeper motor and the like.
[0013] In one embodiment, the controller 112 regulates opening of the electrical valve 106 until a light-off temperature of the catalyst is attained. In other words, the electrical valve 106 is kept open until a light-off temperature of the catalyst is attained. In one embodiment, once the light-off temperature is detected, the electrical valve 106 is closed by the controller 112.
[0014] The controller 112 is control unit comprising an Input/ Output interface, a processor, the memory unit 120 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 112 is same as the Engine Control Unit (ECU) of the vehicle 100 or is completely separate and independent from the ECU. If the controller 112 is independent/ separate from the ECU, then the controller 112 accesses the required information from the memory unit of the ECU, to avoid redundancy.
[0015] The temperature of the catalyst is detected by any one of a temperature sensor and an exhaust temperature model. The exhaust temperature model is stored in the memory unit 120 of the controller 112. The exhaust temperature model is a function of at least a throttle position, an engine speed, a lambda value and an ignition angle. Till light-off temperature is detected, the lambda value or air-fuel ratio is used from a calibrated data or map (which is also stored in the memory unit 120). Once the light-off temperature is attained, the controller 112 may use the lambda value from the lambda sensor (if available in the vehicle 100).
[0016] In accordance to another embodiment of the present invention, the controller 112 operates the electrical valve 106 in the open position and close position to switch an air-fuel ratio of the exhaust gas between a rich phase and a lean phase, while the catalyst is above light-off temperature. The controller 112 operates the electrical valve 106 without any feedback from the lambda sensor (even if the lambda sensor is available in the vehicle 100) based on the information that the THC and CO get converted with efficiencies above 90% above air-fuel ratio/ lambda value = 1 and has less than 90% conversion efficiencies below lambda value = 1. In case of NOx, the conversion efficiency is greater than 90% below lambda value 1 and is below 10% for lambda is greater than 1.
[0017] The ECU operates the engine 110 (fuel injection) based on pre-calibrated settings of load demand from Throttle position sensor 116, MAP sensor (optional) for amount of air flow, engine position and engine speed from a crankshaft position sensor 118, and the like. The ECU operates the engine 110 to near stoichiometric air-fuel ratio (but richer) without taking any feedback from the lambda sensor if available. The controller 112 is adapted to open the electrical valve 106 when the lean toggle of air-fuel ratio is to be initiated, which signifies to increase the presence of oxygen in the exhaust gas. When the electrical valve 106 is opened, fresh air enters into the exhaust conduit 104 providing excess of oxygen to the exhaust gas. The excess oxygen in the exhaust conduit 104 boosts the catalytic conversion of THC and CO yet not affecting the NOx conversion since NOx conversion is lower at this point. After a time based on the engine speed and the load demand, the controller 112 switches the electrical valve 106 to close position to start rich toggle. The rich toggle signifies less oxygen in the exhaust gas, i.e. no air is injected into the exhaust conduit 104. Thus keeping the ideal condition of NOx conversion intact. Again after some time based on the engine speed and load demand, the controller 112 switches the electrical valve 106 to open position to start lean toggle. The switching or toggle between the rich and lean phase is continued by the controller 112 based on the load demand and the engine speed. Other vehicle/engine parameters may be used but without taking real time values. Hence, without hampering the NOx conversion, the controller 112 is able to improve THC and CO conversion efficiencies. The controller 112 is ideally used in but not limited to a lower segment bike where the engine out NOx is very low, but THC and CO are very high. The controller 112 opens the electrical valve 106 for lean toggle and closes for the rich toggle. The frequency of switching of the electrical valve 112 is variable as per the requirement.
[0018] The controller 112 operates the electrical valve 106 in open loop till light-off temperature of the catalyst is detected. The term open loop signifies without using the real time output of the lambda sensor (even if installed in the vehicle 100). Once the catalyst light-off is achieved, the switching of exhaust lambda between rich and lean is performed by controlling the electrical valve 106. The switching between rich and lean phase of exhaust gas in a conventional vehicle 100 is achieved by increasing and decreasing the fueling of a fuel injector. But in the vehicle 100 with air injection at exhaust conduit 104, the controller 112 performs the switching by operating the electrical valve 106 to ON and OFF positions, where the fueling is kept constant and slightly richer as per the load demand. When the electrical valve 106 is operated/ actuated to open/ ON position, the fresh air flows into the exhaust conduit 104. The fresh air lean out the exhaust gas to signify a lean toggle and when the electrical valve 106 is in close/ OFF position, the exhaust gas without the presence of any fresh air, becomes rich signifying the rich toggle.
[0019] The controller 112 ensures maintaining the lambda switching strategy such that THC, CO and NOx are converted optimally. Further, since there is no change in the amount of fueling, the controller 112 is usable in a carbureted based vehicle 100 without lambda sensor. The controller 112 needs only a feedback of Engine RPM from crankshaft position sensor 118 and load demand from the throttle position sensor 116.
[0020] In accordance to an embodiment of the present invention, the controller 112 retards an ignition angle to increase temperature of exhaust gases and thereby to aid in early activation of the catalyst. As mentioned above, the fresh air flows from the air box through the electrical valve 106 and the reed valve 108 to the exhaust conduit 104 (near the exhaust port) and meets with hot exhaust gases which contains THC, CO and NOx. The fresh air reacts with THC and CO in this hot environment and oxidizes to CO2 and H2O. Since this oxidation reaction is exothermic reaction, more heat is generated and passed on to the catalyst, which advances the catalyst light-off. But more often, while starting the vehicle 100 from a cold phase, the engine block is cold. Also the exhaust temperatures is not high enough to facilitate the oxidation reaction. However, now the controller 112 is adapted to retard the ignition angle during the cold phase operation which leads to rise in the temperature of the exhaust gas. The additional heat generated, further advances the catalyst light-off, i.e. the additional heat supplied from the exothermic oxidation reaction and catalyst heating leads to faster catalyst light-off. This is called catalyst heating. The controller 112 ensures there is ample amount heat available in the exhaust conduit 104, near the exhaust port to facilitate the oxidation reaction. The catalyst heating is continued until the catalyst light-off temperature is attained. The controller 112 uses the air injection and catalyst heating in tandem to achieve oxidation of THC and CO during cold phase of the engine 110.
[0021] Though the lambda sensor (if available) is active when the engine 110 is started, the controller 112 does not take input from the same till catalyst light-off is achieved, to ensure that there is an oxygen rich environment in the exhaust conduit 104 till catalyst light-off, to increase the catalytic conversion of THC and CO. Since during cold phase, there is predominantly more THC and CO rather that NOx, the controller 112 controls the air injection strategically with catalyst heating to attain THC and CO purification while not altering the NOx concentrations.
[0022] In accordance to yet another embodiment of the present invention, the controller 112 increases and maintains the catalyst at a minimum 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 band lambda sensor is mostly 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 112 is adapted to perform a specific lambda switching strategies for a particular load and engine speed.
[0023] The catalyst ensures maximum conversion when the temperature is above a typical valve such as 400°C. But if the temperature drops below the minimum temperature, the exhaust purification efficiency drops drastically. Thus, the controller 112 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 112 uses a temperature sensor at the catalyst. The minimum temperature may comprise the light-off temperature.
[0024] When the controller 112 detects a loss in temperature, the controller 112 actuates/opens the electrical valve 106 of the air injection to purge fresh air into the exhaust conduit 104. In addition, the controller 112 operates the engine 110 with richer air-fuel ratio such that there is a sizeable amount of THC and CO released. The controller 112 enriches air fuel mixture inside a cylinder of the engine 110. 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 104. The excess heat released reaches to the catalyst and ensures the catalyst is maintained at the required threshold temperatures.
[0025] 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 104. The catalyst heating signifies retardation of ignition angles within the engine 110 cylinders to ensure more energy is released to boost THC oxidation rate along the exhaust conduit 104. Thus, the controller 112 ensures combined effect of air injection and catalyst heating to maintain the catalyst at the required temperatures.
[0026] The controller 112 is applicable 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.
[0027] Fig. 2 illustrates a method for controlling air injection in the exhaust conduit, according to the present invention. The method comprising the steps of, a step 202 comprising measuring temperature of the engine 110 by the temperature sensor 117. The engine temperature is detected to determine a cold phase of the engine 110. The cold phase signifies a cold start or starting the engine 110 in cold or ambient environment after a long time of shut down. A next step 204 comprises regulating opening of the electrical valve 106 by the controller 112 based on the measured engine temperature, to introduce air into an exhaust conduit 104, upstream of the catalyst of the ETU 114. The step 204 of regulating opening of the electrical valve 106 is performed when the measured temperature of the engine 110 is detected below a threshold temperature. After the step 204, the controller 112 performs the next step as calibrated. A next step 206 may comprise opening of the electrical valve 106 is regulated until the light-off temperature of the catalyst is attained. In other words, keeping the electrical valve 106 open until a light-off temperature of the catalyst is attained. Once attained, the controller 112 closes the electrical valve 106. The step 204 and step 206 may be performed simultaneously.
[0028] The step of regulating opening of the electrical valve 106 corresponds to controlling a degree of opening a passage in the tube 102. For example: the passage is partially or half or completely open. The electrical valve 106 is any valve which can be controlled by supplying electricity such as solenoid valve, a linear actuator, a steeper motor and the like.
[0029] In an alternative option, a step 208 and a step 210 is performed after the step 204 comprising switching an air-fuel ratio of the exhaust gas between rich and lean phase by operating the electrical valve 106 to open position and close position after the light-off temperature is attained. Once the catalyst light-off temperature is attained, the controller 112 switches the lambda value of the exhaust gas between rich and lean (rich and lean toggle) by operating the electrical valve 106 to open/ ON position and close/ OFF position, where the fueling is kept constant and slightly richer, as per the load demand. When the electrical valve 106 is operated/ actuated to the open position, the fresh air flows into the exhaust conduit 104. The step 208 corresponds to lean toggle where the fresh air lean out the exhaust gas. The step 210 corresponds to rich toggle when the electrical valve 106 is in close position. The exhaust gas without the presence of any fresh air, becomes rich signifying the rich toggle. Thus optimally converting the pollutants, without the use of lambda sensor.
[0030] In an another alternative option, a step 212 is performed after the step 204 by the controller 112 comprising retarding ignition angle and increasing temperature of exhaust gases, to aid in early activation of the catalyst. By retarding the ignition angles of combustion, more THC and CO are released to the exhaust conduit 104, which in the presence of oxygen supplied by the air injection, oxidizes to H2O and CO2, simultaneously releasing more heat which aids in early activation of the catalyst.
[0031] In yet another alternative, at least one of a step 214 and a step 216 is performed after the step 204 by the controller 112. The step 214 comprises increasing and maintaining temperature of the catalyst above a threshold temperature by enriching air-fuel mixture inside the cylinder of the engine 110 with air injection in the exhaust conduit 104 by controlling the electrical valve 106. The step 216 comprises retarding ignition to release more THC and CO to exhaust, thereby reacting with fresh air and releasing more heat.
[0032] The method is applicable 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.
[0033] In accordance to an embodiment of the present invention, the controllers 112 provides possibility to use air injection in the exhaust conduit 104 at all engine speeds RPMs. Also, the controller 112 enables to perform air injection without interfering with NOx conversion. Further, there is no need to calibrate the opening of the electrical valve 106, as it is operated in open loop i.e. without taking feedback from lambda sensor. The embodiments are applicable and suitable for lower segments with higher THC and lower NOx.
[0034] 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.