System and method for performing on-board engine cleaning routines in a vehicle

Abstract

The present disclosure provides "systems and methods for performing on-board engine cleaning routines in a vehicle." Methods and systems are provided for reducing carbon deposits in an exhaust gas recirculation system of an engine of a vehicle. In one example, a method includes injecting a diesel exhaust fluid into an intake manifold of the engine, carrying the diesel exhaust fluid into the exhaust gas recirculation system, and vaporizing the diesel exhaust fluid in the exhaust gas recirculation system. In this way, any carbon deposits associated with an exhaust gas recirculation valve and / or an exhaust gas recirculation passage can be reduced, which can increase fuel economy and can reduce undesirable emissions.

Description

Technical Field

[0001] This description generally relates to methods and systems for controlling a vehicle engine system via on-board and on-demand technologies to clean specific engine components.

[0002] Background Art / Summary of the Invention

[0003] The Exhaust Gas Recirculation (EGR) system in a vehicle's powertrain is used to recirculate exhaust gas back into the engine's intake system, intended to reduce NOx emissions. However, while reducing NOx, exhaust gas inherently creates a dirty environment containing combustion byproducts. Therefore, soot and other carbonaceous materials can accumulate in the EGR system over time. As one example, the EGR passage in the EGR system can become blocked due to carbon buildup. In another instance, the EGR valve, located in the EGR passage, can become overloaded due to carbon buildup, which in some cases may cause the EGR valve to degrade (e.g., stuck in at least a partially open position, or stuck in a fully closed position). A stuck EGR valve or a blocked EGR passage can lead to increased temperatures in the vehicle's exhaust system, which can, in some cases, cause exhaust system degradation. Furthermore, a blocked EGR passage or a stuck EGR valve can increase undesirable emissions in the vehicle. In some cases, special additives can be used to clean the EGR system; however, such methods may be invasive and / or may require vehicle mechanic inspection.

[0004] The inventors have recognized these problems and have developed systems and methods herein for at least partially addressing them. In one example, a method includes reducing carbon deposits in the exhaust gas recirculation (EGR) system of a vehicle's engine, the EGR system being configured to deliver at least a portion of the exhaust gas in the exhaust manifold to the engine's intake manifold by injecting diesel exhaust fluid into the engine's exhaust manifold and delivering the diesel exhaust fluid to the EGR system. In this way, carbon deposits can be reduced both on-board and on-demand.

[0005] In one example of the method, delivering the diesel exhaust fluid to the exhaust gas recirculation system may include: simultaneously injecting the diesel exhaust fluid into the exhaust manifold for a predetermined duration while rotating the engine in the opposite direction without fuel. In this example, after delivering the diesel exhaust fluid to the exhaust gas recirculation system, the engine is operated to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system.

[0006] The advantages and other advantages and features described herein will readily become apparent from the following detailed description, taken alone or in conjunction with the accompanying drawings.

[0007] It should be understood that the above summary is provided to introduce, in a simplified form, a series of concepts further described in the detailed description. This is not intended to identify key or essential features of the subject matter for which protection is sought, and the scope of the subject matter for which protection is sought is uniquely defined by the claims following the detailed description. Furthermore, the subject matter for which protection is sought is not limited to implementations that address any of the shortcomings described above or in any part of this disclosure. Attached Figure Description

[0008] Figure 1 An exemplary vehicle propulsion system is schematically shown.

[0009] Figure 2A An exemplary vehicle system is illustrated schematically, having a diesel exhaust fluid (DEF) system configured to inject a reducing agent into the exhaust system of the engine.

[0010] Figure 2B An exemplary vehicle system is schematically shown having a DEF system configured to inject a reducing agent into the exhaust and / or intake systems of the engine.

[0011] Figures 3A to 3B An exemplary H-bridge circuit is schematically shown that can be used to rotate a vehicle engine in either the forward or reverse direction.

[0012] Figure 4 This diagram shows a high-level flowchart for performing the cleaning operation on the engine cylinders.

[0013] Figure 5 A high-level flowchart is shown for performing cleaning operations on the exhaust gas recirculation system.

[0014] Figure 6 A high-level flowchart is shown for another example of performing a cleaning operation on an exhaust gas recirculation system.

[0015] Figure 7 Describing for use according to Figure 4 An exemplary timeline of the method used to perform engine cylinder cleaning operations.

[0016] Figure 8 Describing for use according to Figure 5 An exemplary timeline of the method for performing exhaust gas recirculation system cleaning operations.

[0017] Figure 9 Describing for use according to Figure 6 An exemplary timeline of the method for performing exhaust gas recirculation system cleaning operations. Detailed Implementation

[0018] The following description relates to systems and methods for performing on-board and on-demand cleaning operations to reduce or remove carbon deposits associated with various engine components. These systems and methods may include vaporizing diesel exhaust fluid (DEF) from a DEF injection system, which can cause the moisture in the DEF to be converted into vapor, which can effectively clean carbon deposits. Figure 1 This is particularly useful in hybrid vehicles described herein, where a motor can be used to turn an engine without fuel. The system and method may include a manner in which DEF is delivered to an exhaust gas recirculation (EGR) system, such as... Figure 2A The exhaust gas recirculation system is described below. In one example, DEF can be injected into the exhaust manifold (see [link]). Figure 2A In this process, the DEF is delivered to the EGR system by causing the engine to rotate in the reverse direction without fuel, when the EGR valve is open. In another example, this can be achieved via... Figure 2B The DEF line described herein injects DEF into the intake manifold, where the engine can be rotated forward without fuel, provided the EGR valve is open, to deliver the DEF to the EGR system. In either case, after delivering the DEF to the EGR system, the engine can operate in a combustion mode to direct heat to the EGR system, thus evaporating the moisture in the DEF. This effectively cleans carbon deposits associated with the EGR valve or EGR passage. In another example, DEF can be injected into the intake manifold while the engine is burning air and fuel, allowing the DEF to be drawn into the engine, thereby cleaning carbon deposits in the engine cylinders as the DEF vaporizes within the cylinders.

[0019] To enable an engine to rotate in either the forward or reverse direction without fuel, one can utilize, for example, [the following method / mechanism]. Figures 3A to 3B The H-bridge depicted in the image. Figure 4 A method is described in which carbon deposits can be removed from engine cylinders by injecting DEF into the intake manifold. Figure 5 A method is described in which carbon deposits can be removed from the EGR system by injecting DEF into the intake manifold, and Figure 6 A method is described in which carbon deposits can be removed from the EGR system by injecting DEF into the exhaust manifold. Figure 7 The description is used for execution. Figure 4 The timeline of engine cylinder cleaning operations, in Figure 8 The description is used for execution. Figure 5 The timeline of EGR system cleaning operations, and Figure 9 The description is used for execution. Figure 6Timeline of EGR system cleaning operations.

[0020] Figure 1 An exemplary vehicle propulsion system 100 is described. The vehicle propulsion system 100 includes a fuel-burning engine 110 and a motor 120. As a non-limiting example, the engine 110 includes an internal combustion engine and the motor 120 includes an electric motor. The motor 120 can be configured to utilize or consume energy sources different from those of the engine 110. For example, the engine 110 can consume liquid fuel (e.g., gasoline) to produce engine output, while the motor 120 can consume electrical energy to produce motor output. Therefore, a vehicle having the propulsion system 100 can be referred to as a hybrid electric vehicle (HEV).

[0021] The vehicle propulsion system 100 can utilize various operating modes depending on the operating conditions encountered by the vehicle propulsion system. Some of these modes allow the engine 110 to remain in a shut-off state (i.e., set to be deactivated), in which combustion of fuel at the engine is stopped. For example, under selected operating conditions, when the engine 110 is deactivated, the motor 120 can propel the vehicle via the drive wheels 130, as indicated by arrow 122.

[0022] During other operating conditions, engine 110 can be set to a deactivated state (as described above), while motor 120 can be operated to charge energy storage device 150. For example, motor 120 can receive wheel torque from drive wheels 130, as indicated by arrow 122, whereby the motor can convert the vehicle's kinetic energy into electrical energy for storage in energy storage device 150, as indicated by arrow 124. This operation can be referred to as regenerative braking of the vehicle. Therefore, in some instances, motor 120 can provide generator functionality. However, in other instances, generator 160 can alternatively receive wheel torque from drive wheels 130, whereby the generator can convert the vehicle's kinetic energy into electrical energy for storage in energy storage device 150, as indicated by arrow 162.

[0023] During other operating conditions, engine 110 can be operated by burning fuel received from fuel system 140, as indicated by arrow 142. For example, when motor 120 is deactivated, engine 110 can be operated to propel the vehicle via drive wheels 130, as indicated by arrow 112. During other operating conditions, engine 110 and motor 120 can be operated separately to propel the vehicle via drive wheels 130, as indicated by arrows 112 and 122 respectively. This configuration, where the engine and motor can selectively propel the vehicle, can be referred to as a parallel-type vehicle propulsion system. It should be noted that in some instances, motor 120 can propel the vehicle via a first set of drive wheels, and engine 110 can propel the vehicle via a second set of drive wheels.

[0024] In other instances, the vehicle propulsion system 100 can be configured as a tandem type vehicle propulsion system, whereby the engine does not directly propel the drive wheels. Instead, the engine 110 can be operated to supply power to the motor 120, which in turn can propel the vehicle via the drive wheels 130, as indicated by arrow 122. For example, during selected operating conditions, the engine 110 can drive the generator 160, as indicated by arrow 116, which can then supply electrical energy to one or more of the motors 120, as indicated by arrow 114, or to the energy storage device 150, as indicated by arrow 162. As another example, the engine 110 can be operated to drive the motor 120, which can then provide generator functionality to convert engine output into electrical energy, which can be stored in the energy storage device 150 for later use by the motor.

[0025] In other examples, which will be discussed in more detail below, as illustrated by arrow 186, motor 120 can be configured to cause the engine to rotate in a forward (e.g., default orientation) or reverse orientation without fuel, using energy provided by energy storage device 150.

[0026] Fuel system 140 may include one or more fuel storage tanks 144 for storing fuel on the vehicle. For example, fuel tank 144 may store one or more liquid fuels, including (but not limited to): gasoline, diesel, and ethanol fuel. In some instances, fuel may be stored on the vehicle as a mixture of two or more different fuels. For example, fuel tank 144 may be configured to store a mixture of gasoline and ethanol (e.g., E10, E85, etc.) or a mixture of gasoline and methanol (e.g., M10, M85, etc.), whereby these fuels or fuel mixtures can be supplied to engine 110 as indicated by arrow 142. Other suitable fuels or fuel mixtures may be supplied to engine 110, where they can be burned at the engine to produce engine output. The engine output may be used to propel the vehicle, as indicated by arrow 112, or to recharge energy storage device 150 via motor 120 or generator 160.

[0027] In some instances, the energy storage device 150 may be configured to store electrical energy that can be supplied to other electrical loads residing in the vehicle (in addition to the motor), including cabin heating and air conditioning, engine starting, headlights, cabin audio and video systems, etc. As a non-limiting example, the energy storage device 150 may include one or more batteries and / or capacitors.

[0028] The control system 190 can communicate with one or more of the engine 110, motor 120, fuel system 140, energy storage device 150, and generator 160. The control system 190 can receive sensor feedback information from one or more of the engine 110, motor 120, fuel system 140, energy storage device 150, and generator 160. Furthermore, the control system 190 can send control signals to one or more of the engine 110, motor 120, fuel system 140, energy storage device 150, and generator 160 in response to this sensor feedback. The control system 190 can receive instructions from the vehicle operator 102 regarding the output of the vehicle propulsion system requested by the operator. For example, the control system 190 can receive sensor feedback from a pedal position sensor 194 that communicates with pedal 192. Pedal 192 can schematically refer to the brake pedal and / or accelerator pedal. Furthermore, in some instances, the control system 190 can communicate with a remote engine start receiver 195 (or transceiver) that receives a wireless signal 106 from a remote key 104 having a remote start button 105. In other instances (not shown), remote engine start can be initiated via a cellular phone or smartphone-based system, where the user's cellular phone sends data to a server and the server communicates with the vehicle to start the engine.

[0029] Energy storage device 150 can periodically receive electrical energy from a power source 180 residing outside the vehicle (e.g., not part of the vehicle), as indicated by arrow 184. As a non-limiting example, vehicle propulsion system 100 can be configured as a plug-in hybrid electric vehicle (PHEV), whereby electrical energy can be supplied from power source 180 to energy storage device 150 via power transmission cable 182. During a recharging operation of energy storage device 150 from power source 180, power transmission cable 182 can electrically couple energy storage device 150 and power source 180. When operating the vehicle propulsion system to propel the vehicle, power transmission cable 182 can be disconnected between power source 180 and energy storage device 150. Control system 190 can identify and / or control the amount of electrical energy stored at energy storage device, which may be referred to as state of charge (SOC).

[0030] In other instances, the electrical transmission cable 182 may be omitted, allowing electrical energy to be wirelessly received from the power source 180 at the energy storage device 150. For example, the energy storage device 150 may receive electrical energy from the power source 180 via one or more of electromagnetic induction, radio waves, and electromagnetic resonance. Therefore, it should be understood that any suitable method can be used to recharge the energy storage device 150 from a power source that does not constitute part of the vehicle. In this way, the motor 120 can propel the vehicle by utilizing energy sources other than the fuel used by the engine 110.

[0031] The fuel system 140 can periodically receive fuel from a fuel source located outside the vehicle. As a non-limiting example, the vehicle propulsion system 100 can be fueled by receiving fuel via a fuel dispensing device 170, as indicated by arrow 172. In some instances, the fuel tank 144 can be configured to store fuel received from the fuel dispensing device 170 until said fuel is supplied to the engine 110 for combustion. In some instances, the control system 190 can receive an indication of the level of fuel stored in the fuel tank 144 via a fuel level sensor. The level of fuel stored in the fuel tank 144 (e.g., identified by the fuel level sensor) can be communicated to the vehicle operator via, for example, a fuel gauge or indication in the vehicle dashboard 196.

[0032] The vehicle propulsion system 100 may also include an ambient temperature / humidity sensor 198 and a roll stability control sensor (e.g., lateral and / or longitudinal and / or yaw rate sensors 199). The vehicle instrument panel 196 may include indicator lights and / or a text-based display showing messages to the operator. The vehicle instrument panel 196 may also include various input elements for receiving operator input, such as buttons, touchscreens, voice input / recognition, etc. For example, the vehicle instrument panel 196 may include a refueling button 197 that the vehicle operator can manually actuate or press to initiate refueling. For example, as described in more detail below, in response to the vehicle operator actuating the refueling button 197, the fuel tank in the vehicle may be depressurized to allow refueling to be performed.

[0033] The control system 190 can communicatively couple to other vehicles or infrastructure using suitable communication technologies well known in the art. For example, the control system 190 can couple to other vehicles or infrastructure via a wireless network 131, which may include Wi-Fi, Bluetooth, cellular service types, wireless data transmission protocols, etc. The control system 190 can broadcast (and receive) information about vehicle data, vehicle diagnostics, traffic conditions, vehicle location information, vehicle operating procedures, etc., via vehicle-to-vehicle (V2V), vehicle-to-infrastructure-to-vehicle (V2I2V), and / or vehicle-to-infrastructure (V2I or V2X) technologies. The communication and information exchanged between vehicles can be direct between vehicles or can be multi-hop communication and information. In some instances, longer-range communication (e.g., WiMax) can be used to replace or combine with V2V or V2I2V to extend the coverage area by several miles. In other instances, the vehicle control system 190 can communicatively couple to other vehicles or infrastructure via a wireless network 131 and the Internet (e.g., the cloud), which are generally known in the art.

[0034] Vehicle system 100 may also include an onboard navigation system 132 (e.g., a Global Positioning System) that the vehicle operator can interact with. Navigation system 132 may include one or more position sensors for assisting in estimating vehicle speed, vehicle altitude, vehicle location / position, etc. This information can be used to infer engine operating parameters, such as local air pressure. As discussed above, control system 190 may be further configured to receive information via the Internet or other communication networks. Information received from GPS can be cross-referenced with information available via the Internet to determine local weather conditions, local vehicle regulations, etc.

[0035] Figure 2A A schematic depiction of vehicle system 206 is shown. It will be understood that vehicle system 206 may include components that interact with... Figure 1The vehicle system 206 is the same as the vehicle system 100 depicted. Vehicle system 206 includes an engine system 208 coupled to an emission control system 251 and a fuel system 218. It is understood that the fuel system 218 may include components similar to those in the emission control system 251 and the fuel system 218. Figure 1 The fuel system is the same as the fuel system 140 depicted. The emission control system 251 includes a fuel vapor container or filter canister 222 that can be used to capture and store fuel vapor. The engine system 208 may include an engine 110 having a plurality of cylinders 230. The engine 110 includes an engine intake system 223 and an engine exhaust system 225. The engine intake port 223 includes a throttle valve 262 in fluid communication with an engine intake manifold 244 via an intake passage 242. In some instances, the throttle valve 262 may include an electronic throttle valve that can be commanded to a desired position via a controller 212. Additionally, the engine intake port 223 may include an air box and filter (not shown) positioned upstream of the throttle valve 262. The engine exhaust system 225 includes an exhaust manifold 248 leading to an exhaust passage 235 that delivers exhaust gas to the atmosphere. The exhaust duct may lead to one or more exhaust aftertreatment devices (e.g., 226, 229, 236) and a reducing agent delivery and storage system, such as a diesel exhaust fluid (DEF) system 238. In some instances, the exhaust duct may include an exhaust tuning valve 299, which may include, for example, a butterfly valve and may be controllable via a controller to reach a fully open or fully closed position, or somewhere between fully open and / or fully closed.

[0036] Exhaust aftertreatment devices can be arranged along exhaust duct 235 in various orders and / or combinations. For example, a selective catalytic reduction (SCR) catalyst 229 can be downstream of a diesel oxidation catalyst (DOC) 226. In some instances, a nitrogen oxide sensor (NOx sensor) 298 can be located downstream of the SCR and can be configured to measure NOx concentration. A diesel particulate filter (DPF) 236 can be downstream of the SCR catalyst 229. It should be understood that in Figure 2A The emission control device of the exhaust system 225 shown is exemplary in nature. Various other emission control devices and configurations may be included in the engine exhaust system 225. For example, the exhaust system 225 may include an SCR catalyst followed only by a DPF. In another instance, the exhaust system 225 may include only an SCR catalyst. In yet another instance, the DPF may be located upstream of the SCR catalyst, or a combined DPF / SCR catalyst may be used.

[0037] Engine exhaust system 225 may also include a reducing agent delivery and / or storage system, such as DEF system 238. DEF may be a liquid reducing agent, such as a mixture of urea and water, stored in a storage container (e.g., a tank). In one example, DEF system 238 may include a DEF canister 239 for on-board DEF storage and a DEF delivery line 240 coupling the DEF canister 239 to exhaust duct 235 via an injector at or upstream of SCR catalyst 229. DEF canister 239 may take various forms and may include a funnel neck 241 and a corresponding cap and / or chute in the vehicle body. Funnel neck 241 may be configured to receive nozzles for replenishing DEF.

[0038] DEF system 238 may also include a first DEF injector 243 in line 240, which injects DEF into the exhaust manifold upstream of SCR catalyst 229. The first DEF injector 243 may be used to control the timing and amount of DEF injection via control system 214. More specifically, the first DEF injector 243 may include a first DEF injector valve 292. The DEF injector valve 292 may be configured as an active solenoid valve, which can be actuated to open and close via, for example, commands from control system 214. DEF system 238 may also include a DEF pump 246. DEF pump 246 may be used to pressurize DEF and deliver DEF to line 240. DEF system 238 may also include a DEF line heater 247 for heating DEF line 240. For example, DEF line heater 247 can warm the DEF fluid at low temperatures on its way to the DEF pump to maintain DEF fluid viscosity. DEF line heater 247 can be a resistive heater or various other configurations. DEF line heater 247 can be coupled to energy storage device 150, which may include a battery and can be enabled and controlled, for example, via control system 214.

[0039] It is understood that by injecting DEF (urea-water mixture) upstream of the SCR into the hot exhaust gas duct, the urea can be decomposed into ammonia (NH3) in the hot exhaust gas and absorbed by the SCR unit. The ammonia then reduces NOx to nitrogen in the presence of the SCR catalyst. Therefore, it is understood that in some instances, NOx sensors can be used to infer the timing and amount of DEF injection into the exhaust gas in order to effectively reduce NOx emissions by using ammonia-filled SCR.

[0040] It will be understood that other components, such as various valves and sensors, can be included in the engine. For example, a bar pressure sensor 213 can be included in the engine intake. In one instance, the bar pressure sensor 213 may be a manifold air pressure (MAP) sensor and may be coupled to the engine intake downstream of the throttle valve 262. The bar pressure sensor 213 may depend in part on the throttle valve or throttle valve conditions, such as when the throttle valve 262 is open by a amount greater than a threshold, in order to accurately determine the bar pressure.

[0041] A humidity sensor 258 may be positioned downstream of the throttle valve 262 in the engine intake port. The humidity sensor may be positioned to determine, for example, the humidity of the intake air flowing through the intake manifold 242. In one example, the humidity sensor 258 may measure the relative humidity and temperature of the gas to which the sensor is exposed. Based on the relative humidity and temperature, the specific humidity of the gas (e.g., the amount of water per unit mass of gas flow) may be determined. To measure the relative humidity, a dew point sensor (using, for example, a cold mirror) or a wet-bulb / dry-bulb sensor may be used. In other examples, absolute humidity may be measured by a capacitive sensor, and the temperature and / or pressure of the air may be estimated or measured to calculate the relative humidity and / or specific humidity.

[0042] Specifically, engine control systems often want to know specific humidity, such as the humidity ratio of the air. In other words, the engine control system wants to know how much water vapor (or some other diluent) is in the air. Some engine humidity sensors measure absolute humidity, such as the mass of water in a volume of air. In many cases, the humidity sensor can: measure absolute humidity; convert the absolute humidity to relative humidity based on selected measurements and assumptions; send the relative humidity data to controller 212, which then converts it back to absolute humidity, and subsequently to specific humidity. To perform such conversions, pressure and temperature at the measurement point can be measured or inferred. Therefore, in some instances, a pressure sensor 213 and a temperature sensor 260 may be included in close proximity to the humidity sensor 258.

[0043] In some instances, engine system 208 may include an engine speed sensor 265. Engine speed sensor 265 may be attached to the crankshaft (not shown) of engine 110 and may transmit engine speed to controller 212. In some instances, engine system 208 may include an engine torque sensor 267, which may be coupled to the crankshaft (not shown) of engine 110 to measure torque generated by the engine. In one instance, the engine torque sensor may be used to indicate whether one or more engine cylinders are operating as required, or whether there are undesirable problems with the engine cylinders, such as carbon deposits on the cylinder intake / exhaust valves.

[0044] Engine system 208 may also include an exhaust gas recirculation (EGR) system 249 that receives at least a portion of the exhaust gas stream leaving engine 110 and returns the exhaust gas to engine intake manifold 244 downstream of throttle valve 262. Under certain conditions, EGR system 249 can be used to regulate the temperature and / or dilution of the air-fuel mixture in the combustion chamber, thereby providing a method for controlling ignition timing during certain combustion modes. Furthermore, under certain conditions, a portion of the combustion gases can be retained or trapped in the combustion chamber by controlling exhaust valve timing. EGR system 249 is shown as forming a common EGR passage 250 from exhaust passage 235 to intake passage 242.

[0045] In some instances, exhaust system 225 may also include a turbocharger (not shown) comprising a turbine and a compressor coupled on a common shaft. The turbine may be coupled within exhaust duct 235, while the compressor may be coupled within intake duct 242. A portion of the exhaust flow from engine 110 impacts the turbine blades, causing the turbine blades to rotate about a common shaft. The compressor may be coupled to the turbine such that it is actuated when the turbine blades are rotated. When actuated, the compressor can then direct pressurized fresh air to intake manifold 244, whereby the pressurized fresh air can then be directed to engine 110. In a system where EGR passage 250 is coupled upstream of the turbine to engine exhaust duct 225 and downstream of the compressor to intake duct 242, the EGR system can be considered a high-pressure EGR system. Alternatively, the EGR passage may be coupled downstream of the turbine and upstream of the compressor (low-pressure EGR system). It is understood that the systems and methods described herein can be applied to high-pressure EGR systems or low-pressure EGR systems without departing from the scope of this disclosure.

[0046] EGR valve 253 can be connected within EGR passage 250. EGR valve 253 can be configured as an active solenoid valve, actuated to allow exhaust flow into intake manifold 244. The portion of the exhaust flow emitted from engine 110 that is permitted to pass through EGR system 249 and return to engine 110 can be metered by measured actuation of EGR valve 253, which can be regulated by controller 212. Actuation of EGR valve 253 can be based on various vehicle operating parameters and a calculated total EGR flow rate.

[0047] One or more EGR coolers 254 may be connected within the EGR passage 250. The EGR coolers 254 can be used to reduce the overall temperature of the EGR flow before it is delivered to the intake manifold 244, in which the EGR flow can be combined with fresh air and directed to the engine 110. The EGR passage 250 may include one or more flow confinement zones 255. One or more pressure sensors 256 may be connected at or near the flow confinement zone 255. The diameter of the flow confinement zone is thus used to determine the total volumetric flow rate through the EGR passage 250.

[0048] An intake system hydrocarbon trap (AIS HC) 257 can be placed in the intake manifold of engine 110 to absorb fuel vapors originating from unburned fuel in the intake manifold, turbid fuel from degraded fuel injectors, and / or fuel vapors emitted during crankcase ventilation during engine shutdown cycles. The AIS HC may comprise a stack of continuously layered polymer sheets saturated with HC vapor absorber / desorber material. Alternatively, absorber / desorber material may be filled in the regions between the layers of polymer sheets. The absorber / desorber material may include one or more of carbon, activated carbon, zeolite, or any other HC absorber / desorber material. When the engine is operated, resulting in an intake manifold vacuum and the resulting airflow across the AIS HC 257, the trapped vapors can be passively desorbed from the AIS HC and combusted in engine 110. Thus, during engine operation, intake fuel vapors are stored and desorbed from the AIS HC 257. Additionally, fuel vapors stored during engine shutdown can also be desorbed from the AIS HC during engine operation. In this way, the AIS HC 257 can be continuously loaded and purified, and the trap can reduce evaporative emissions from the intake manifold even when the engine 110 is off.

[0049] Fuel system 218 may include a fuel tank 220 coupled to fuel pump system 221. It will be understood that fuel tank 220 may include components described above... Figure 1The fuel tank 218 is the same as the fuel tank 144 depicted herein. The fuel pump system 221 may include one or more pumps for pressurizing fuel delivered to the injectors (e.g., the exemplary injector 266 shown) of the engine 110. Although only a single injector 266 is shown, additional injectors are provided for each cylinder. It will be understood that the fuel system 218 may be a non-return fuel system, a return fuel system, or various other types of fuel systems. The fuel tank 220 may hold multiple fuel mixtures, including fuels with a certain ethanol concentration range, such as various gasoline-ethanol mixtures, including E10, E85, gasoline, etc., and combinations thereof. A fuel level sensor 234 located in the fuel tank 220 may provide an indication of the fuel level (“fuel level input”) to the controller 212. As depicted, the fuel level sensor 234 may include a float connected to a variable resistor. Alternatively, other types of fuel level sensors may be used.

[0050] Vapor generated in fuel system 218 may be transported to evaporative emission control system 251 via vapor recovery line 231 before being drawn into engine intake port 223. Evaporative emission control system 251 includes fuel vapor filter canister 222. Vapor recovery line 231 may be connected to fuel tank 220 via one or more conduits and may include one or more valves for isolating fuel tank during certain conditions. For example, vapor recovery line 231 may be connected to fuel tank 220 via one or more or a combination of conduits 271, 273, and 275.

[0051] Furthermore, in some instances, one or more fuel tank vent valves may be located in conduits 271, 273, or 275. Fuel tank vent valves can, in particular, allow the fuel vapor filter canister to be maintained at low pressure or vacuum without increasing the fuel evaporation rate from the emission control system (which would otherwise occur with reduced fuel tank pressure). For example, conduit 271 may include a staged vent valve (GVV) 287, conduit 273 may include a fill limit vent valve (FLVV) 285, and conduit 275 may include a staged vent valve (GVV) 283. Additionally, in some instances, a recovery line 231 may be coupled to a fuel filling system 219. In some instances, the fuel filling system may include a fuel tank cap 205 for sealing the fuel filling system relative to the atmosphere. The refueling system 219 is coupled to the fuel tank 220 via a fuel filling tube or neck 211.

[0052] In addition, the refueling system 219 may include a refueling lock 245. In some instances, the refueling lock 245 may be a fuel tank cap locking mechanism. The fuel tank cap locking mechanism may be configured to automatically lock the fuel tank cap in a closed position, making it impossible to open the fuel tank cap. For example, when the pressure or vacuum in the fuel tank is greater than a threshold, the fuel tank cap 205 may be kept locked via the refueling lock 245. In response to a refueling request, such as a request initiated by the vehicle operator, the fuel tank may be depressurized, and the fuel tank cap may be unlocked after the pressure or vacuum in the fuel tank has dropped below a threshold. The fuel tank cap locking mechanism may be a latch or clutch that prevents the removal of the fuel tank cap when engaged. The latch or clutch may be electrically locked, for example, via a solenoid, or mechanically locked, for example, via a pressure diaphragm.

[0053] In some instances, the fuel lock 245 may be a filler valve located at the nozzle of the fuel filler pipe 211. In these instances, the fuel lock 245 may not prevent the removal of the fuel tank cap 205. Instead, the fuel lock 245 may prevent the fuel pump from being inserted into the fuel filler pipe 211. The filler valve may be electrically locked, for example, via a solenoid, or mechanically locked, for example, via a pressure diaphragm.

[0054] In some instances, the refueling lock 245 may be a refueling door lock, such as a latch or clutch that locks a refueling door located in a body panel of a vehicle. The refueling door lock may be electrically locked, for example, via a solenoid, or mechanically locked, for example, via a pressure diaphragm.

[0055] In an example where the refueling lock 245 is locked using an electrical mechanism, for example, the refueling lock 245 can be unlocked via a command from the controller 212 when the fuel tank pressure decreases below a pressure threshold. In an example where the refueling lock 245 is locked using a mechanical mechanism, for example, the refueling lock 245 can be unlocked via a pressure gradient when the fuel tank pressure decreases to atmospheric pressure.

[0056] The emission control system 251 may include one or more emission control devices, such as one or more fuel vapor canisters 222 filled with a suitable adsorbent 286b, the canisters being configured to temporarily trap fuel vapors (including vaporized hydrocarbons) and “operational losses” (i.e., fuel vaporized during vehicle operation) during fuel tank refilling operations. In one example, the adsorbent 286b used is activated carbon. The emission control system 251 may also include a filter canister venting path or venting line 227 that can deliver gases leaving the filter canister 222 to the atmosphere while storing or trapping fuel vapors from the fuel system 218.

[0057] The filter canister 222 may include a buffer 222a, each of which includes an adsorbent. As shown, the volume of the buffer 222a may be smaller than the volume of the filter canister 222 (e.g., a fraction of the filter canister volume). The adsorbent 286a in the buffer 222a may be the same as or different from the adsorbent in the filter canister (e.g., both may include charcoal). The buffer 222a may be positioned within the filter canister 222 such that during filter canister loading, fuel tank vapor is first absorbed into the buffer, and subsequently, when the buffer is saturated, other fuel tank vapor is absorbed into the filter canister. In contrast, during filter canister extraction, fuel vapor is first desorbed from the filter canister (e.g., reaching a threshold amount) and then desorbed from the buffer. In other words, the loading and unloading of the buffer are not synchronized with the loading and unloading of the filter canister. Therefore, the effect of the filter canister buffer is to suppress any fuel vapor peaks flowing from the fuel tank into the filter canister, thereby reducing the likelihood of any fuel vapor peaks reaching the engine. One or more temperature sensors 232 may be coupled to the filter canister 222 and / or within the filter canister. Heat is generated (heat of absorption) when fuel vapor is absorbed by the adsorbent in the filter canister. Similarly, heat is consumed when fuel vapor is desorbed by the adsorbent in the filter canister. In this way, the absorption and desorption of fuel vapor by the filter canister can be monitored and estimated based on the temperature changes within the filter canister.

[0058] When stored fuel vapor is drawn from the fuel system 218 to the engine intake manifold 223 via the extraction line 228 and extraction valve 261, the vent line 227 can also allow fresh air to be drawn into the filter canister 222. For example, the extraction valve 261 may be normally closed but may be opened under certain conditions to provide a vacuum from the engine intake manifold 244 to the fuel vapor filter canister for extraction. In some instances, the vent line 227 may include an air filter 259 disposed upstream of the filter canister 222.

[0059] In some instances, the flow rate of air and vapor between the filter canister 222 and the atmosphere can be regulated by a filter canister vent valve 297 connected within the vent line 227. When the filter canister vent valve 297 is included, it can be a normally open valve, allowing the fuel tank isolation valve 252 (FTIV) to control the venting of the fuel tank 220 to the atmosphere. The FTIV 252 can be positioned between the fuel tank and the fuel vapor filter canister 222 within the conduit 278. The FTIV 252 can be a normally closed valve, allowing fuel vapor from the fuel tank 220 to be released into the fuel vapor filter canister 222 when opened. The fuel vapor can then be released into the atmosphere or extracted into the engine intake system 223 via the filter canister extraction valve 261. In some instances, the FTIV may not be included, while in others it may be included.

[0060] The fuel system 218 can be operated in multiple modes by the controller 212 through selective adjustment of various valves and solenoids. It is understood that the control system 214 may include components described above. Figure 1 The control system 190 described herein is the same control system. For example, the fuel system can be operated in a fuel vapor storage mode (e.g., during fuel tank refueling operation and when the engine is not burning air and fuel), wherein the controller 212 can close the canister extraction valve (CPV) 261 while opening the isolation valve 252 (if included) to direct fuel vapor into the canister 222, while preventing fuel vapor from being directed into the intake manifold.

[0061] As another example, the fuel system can be operated in a refueling mode (e.g., when a vehicle operator requests refueling from the fuel tank), where controller 212 can keep the canister extraction valve 261 closed while opening isolation valve 252 (if included) to depressurize the fuel tank, thereby allowing refueling to proceed. Therefore, isolation valve 252 (if included) can be kept open during refueling to allow fuel vapor to be stored in the canister. The isolation valve can be closed after refueling is complete.

[0062] As another example, the fuel system can be operated in a filter canister extraction mode (e.g., after the emission control ignition temperature has been achieved and the engine is burning air and fuel), where controller 212 can simultaneously open filter canister extraction valve 261 and close isolation valve 252 (if included). In this document, fresh air can be drawn from the intake manifold of the operating engine through vent line 227 and through fuel vapor filter canister 222 to extract stored fuel vapor into intake manifold 244. In this mode, the extracted fuel vapor from the filter canister is burned in the engine. Extraction can continue until the amount of fuel vapor stored in the filter canister falls below a threshold.

[0063] Controller 212 can form part of control system 214. In some instances, control system 214 can be integrated with... Figure 1The control system 190 described herein is identical. Control system 214 is shown as receiving information from a plurality of sensors 216 (various examples of the plurality of sensors described herein) and sending control signals to a plurality of actuators 281 (various examples of the plurality of actuators described herein). As an example, sensors 216 may include an exhaust gas sensor 237, a temperature sensor 233, a pressure sensor 291, a pressure sensor 282, and a filter canister temperature sensor 232 located upstream of the emission control device 270. Other sensors, such as pressure sensors, temperature sensors, air / fuel ratio sensors, and composition sensors, may be coupled to various locations within the vehicle system 206. As another example, actuators may include a throttle valve 262, a fuel tank isolation valve 252, a filter canister extraction valve 261, and a filter canister vent valve 297. Control system 214 may include a controller 212. The controller may receive input data from various sensors, process the input data, and trigger actuators in response to the processed input data based on instructions or codes programmed therein corresponding to one or more routines. Figures 4 to 6 Describe an exemplary control routine.

[0064] In some instances, the controller can be placed in a power-reduction mode or a sleep mode, where it maintains only essential functions and operates with lower battery consumption than in the corresponding wake-up mode. For example, the controller can be placed in sleep mode after a vehicle shutdown event to perform diagnostic routines for a period of time following the event. The controller may have a wake-up input that allows it to return to wake-up mode based on input received from one or more sensors. For example, opening a vehicle door can trigger a return to wake-up mode. In other instances, the controller may need to wake up to perform such methods. In this instance, the controller may remain awake for a duration called a time period, where waking the controller to perform an extended shutdown function allows it to wake up to perform diagnostic routines. In another instance, wake-up capability allows circuitry to wake the controller when diagnostics are requested (e.g., when a humidity sensor diagnostic is requested or when conditions for performing such diagnostics are met).

[0065] Controller 212 can intermittently perform unintended evaporative emission detection routines on fuel system 218 and / or evaporative emission system 251 to confirm that unintended evaporative emissions are not present in said fuel system and / or evaporative emission system. Therefore, the evaporative emission detection routine can be performed using engine-off natural vacuum (EONV) and / or vacuum supplemented from a vacuum pump during engine shutdown (engine-off test), said EONV being generated due to temperature and pressure changes at the fuel tank after engine shutdown. Alternatively, the evaporative emission detection routine can be performed while the engine is running by operating a vacuum pump and / or using engine intake manifold vacuum. In some configurations, a filter canister vent valve (CVV) 297 can be connected within vent line 227. CVV 297 can be used to adjust the flow rate of air and vapor between filter canister 222 and atmosphere. CVV can also be used for diagnostic routines. When the CVV is included, it can be opened during fuel vapor storage operations (e.g., during refueling and when the engine is not running) to allow air stripped of fuel vapor after passing through the filter canister to be vented to the atmosphere. Similarly, during extraction operations (e.g., during filter canister regeneration and when the engine is running), the CVV can be opened to allow a flow of fresh air to remove fuel vapor stored in the filter canister. In some instances, CVV 297 can be a solenoid valve, wherein opening or closing of the valve is performed via actuation of the filter canister vent solenoid. Specifically, the filter canister vent valve can be an opening that is closed when the filter canister vent solenoid is actuated. In some instances, CVV 297 can be configured as a latchable solenoid valve. In other words, when the valve is in the closed configuration, the valve latches closed without requiring additional current or voltage. For example, the valve can be closed using a 100ms pulse and subsequently opened using another 100ms pulse at a later time. In this way, the amount of battery power required to maintain the CVV closed is reduced. Specifically, the CVV can be turned off when the vehicle is turned off, thus maintaining the fuel emission control system in a sealed manner relative to the atmosphere while preserving battery power.

[0066] Turn now Figure 2B This illustrates an example of vehicle system 293. This is understandable. Figure 2B Most components of vehicle system 293 are in Figure 2A The components depicted therein are the same as those depicted for vehicle system 206. Therefore, the same figures are used to illustrate the same points. Figure 2A and Figure 2B The same components are used in the previous section, and for the sake of brevity, they will not be repeated here.

[0067] exist Figure 2BIn the exemplary vehicle system 293, the engine exhaust system may include the DEF system 238B as discussed above. The DEF system 238B may include components that are compatible with... Figure 2A The DEF system 238B described herein contains the same components as DEF system 238, except that DEF system 238B may also include a second DEF delivery line 294 originating from DEF delivery line 240. The second DEF delivery line 294 may connect the DEF canister 239 to the intake manifold 244 via a second DEF injector 295. The second DEF injector 295 may include a second DEF injector valve 296, which may be configured as an active solenoid valve, for example, actuated by commands from control system 214. Therefore, as will be discussed in detail below, there may be vehicle operating conditions or situations in which injecting DEF into the intake manifold may be beneficial. Alternatively, there may be other situations in which injecting DEF into the exhaust manifold 235 may be beneficial. Importantly, it can be understood that, for example, DEF may be injected into the intake manifold 244 and / or the exhaust manifold 235. Figure 2B In some cases, DEF can be injected into the intake manifold without also injecting DEF into the exhaust duct 235. Alternatively, DEF can be injected into the exhaust duct 235 without also injecting DEF into the intake manifold 244. Furthermore, there may be some instances where DEF is injected into both the intake manifold 244 and the exhaust duct 235 simultaneously or nearly simultaneously. This will be discussed below regarding... Figures 4 to 6 Detailed examples are described for injecting DEF into one or more of the intake manifold 244 and / or exhaust manifold 235 in order to perform a specific diagnostic procedure.

[0068] In short, in one instance, DEF can be injected into the intake manifold 244 while the engine is burning air and fuel to draw DEF into one or more cylinders of the engine, thereby cleaning carbon deposits (e.g., on the top of the cylinder pistons, or on the intake / exhaust valves). In some instances, the air / fuel ratio can be adjusted to a rich air / fuel ratio to compensate for the injected DEF while it is being drawn into one or more cylinders of the engine. Importantly, this cleaning of carbon deposits can be performed on-vehicle and when needed. More specifically, as discussed, the DEF may comprise a mixture of urea and water (urea components and water components). Thus, when the mixture of fuel, air, and DEF is introduced into one or more engine cylinders and ignited, the water component of the DEF can be converted into vapor (e.g., vaporized), which can effectively remove carbon deposits. DEF can be injected into the intake manifold during engine idling conditions. Engine idling conditions may include, in some instances, a cut-off event, whereby the controller is kept in an awake state to reduce carbon buildup, and whereby the controller is put into sleep mode after the test is completed. In this instance, it can be understood that the DEF injected into the intake manifold may include a threshold amount smaller than the amount of fuel supplied to the engine during DEF injection into the intake manifold.

[0069] Another example includes a method comprising, in a first operating condition of the vehicle (including an indication of degraded performance in one or more cylinders of the engine and an indication of no degraded performance in the EGR system), injecting DEF into the engine's intake manifold with the exhaust gas recirculation valve closed to mitigate the degraded performance of the one or more cylinders. In a second operating condition of the vehicle (including an indication of degraded performance in the EGR system and an indication of no degraded performance in one or more cylinders and / or an indication of degraded performance in one or more cylinders of the engine), the method includes injecting diesel exhaust fluid into the engine's intake manifold with the EGR valve open to mitigate the degraded performance of the exhaust gas recirculation system. In the first operating condition, DEF is injected into the intake manifold while the engine is burning air and fuel, and the method may further include stopping DEF injection into the intake manifold in response to an indication that degraded performance of the one or more engine cylinders has been mitigated, the indication including an indication that carbon deposits associated with the one or more engine cylinders have been reduced or removed. In the second operating condition, DEF can be injected into the intake manifold while the engine is rotating in the forward direction without fuel for a predetermined duration. Once the predetermined duration has elapsed, the engine can be started to burn air and fuel, with one cylinder not receiving fuel, and DEF injection into the intake manifold is maintained while the engine is burning air and fuel and the EGR valve is open. In response to an indication that degradation in the EGR system has been mitigated, DEF injection can be stopped and the EGR valve can be closed. Mitigating degradation in the EGR system can include reducing or removing carbon deposits in the EGR passages of the EGR system and / or removing carbon deposits associated with the EGR valve. In this example, in the second condition, it can be understood that the engine cylinder not receiving fuel does not include one or more cylinders of the engine with the indicated degradation. It can be understood that, as discussed herein, the indication of degradation in the EGR system is in response to a lower-than-expected flow rate in the EGR system when the EGR valve is open under predetermined vehicle operating conditions, and / or a higher-than-expected flow rate in the EGR system when the EGR valve is closed.

[0070] In another example, consider a condition where the EGR flow rate is lower than the expected or desired flow rate. Such low EGR flow can be attributed to carbon deposits on the EGR valve (e.g., 253) or in the EGR passage (e.g., 250). In this example, when the engine is turned in the forward or default direction without fuel (e.g., without burning air and fuel), DEF can be injected into the intake manifold, where the EGR valve is open to deliver liquid DEF to the EGR passage (e.g., 250). After the DEF has been delivered to the EGR passage, the engine can be started to burn air and fuel, generating heat in the exhaust manifold and the EGR passage. With the EGR valve open, heating the DEF by operating the engine to burn air and fuel can cause the vapor from the water component of the DEF to effectively remove the carbon deposits associated with the EGR valve. In other words, after the diesel exhaust fluid has been delivered to the EGR system (e.g., to the EGR passage), the engine can be operated to vaporize the DEF delivered to the EGR system. Furthermore, when the engine is started to burn air and fuel, one engine cylinder may not be started (no fuel is supplied to the deactivated cylinder), and therefore, the deactivated engine cylinder can be used as a route for directing DEF into the EGR passage, where DEF is continuously injected into the intake manifold after the engine is started to burn air and fuel. Such examples may include conditions in which the oxidation catalyst (e.g., 226) is above a threshold temperature (wherein the threshold temperature may include the temperature at which any DEF transported across the oxidation catalyst can be vaporized).

[0071] In another example, a third operating condition for the vehicle may include injecting DEF into the intake manifold of the vehicle's engine and delivering DEF to the EGR system, and a fourth operating condition may include injecting DEF into the vehicle's exhaust manifold and delivering the DEF to the EGR system. In this example, the third and fourth operating conditions may include vaporizing DEF in response to delivering DEF to the EGR system. In this example, the third operating condition may include a temperature above a threshold temperature for an oxidation catalyst (e.g., 226) positioned upstream of the injection point for injecting DEF into the exhaust manifold, wherein the fourth operating condition may include a temperature below the threshold temperature for the oxidation catalyst. In this example, the threshold temperature may include the temperature at which DEF delivered across the oxidation catalyst causes the DEF to evaporate. In this example, in the third operating condition, the engine may be rotating in the forward direction without fuel, while in the fourth operating condition, DEF may be delivered to the EGR system via rotating the engine in the reverse direction without fuel. In the third and fourth conditions, vaporizing the DEF includes starting the engine to burn air and fuel, thereby directing the heat from the engine exhaust to the EGR system. Furthermore, the third operating condition may include a cut-off event, while the fourth operating condition may include a key-on event.

[0072] In another example, the fifth operating condition may include a condition in which carbon deposits are indicated in the EGR system and the temperature of the oxidation catalyst (e.g., 226) is greater than a threshold temperature, and the sixth operating condition may include a condition in which carbon deposits are indicated in the EGR system and the temperature of the oxidation catalyst is less than a threshold temperature. In the fifth operating condition, the engine may be operated in one mode to reduce carbon deposits by injecting DEF into the intake manifold and delivering DEF to the EGR system, while in the sixth operating condition, the engine may be operated in another mode to reduce carbon deposits by injecting DEF into the exhaust manifold and delivering DEF to the EGR system. In this example, one mode (the fifth operating condition) may include rotating the engine in the forward direction without fuel via a motor while injecting DEF into the intake manifold, while the other mode (the sixth operating condition) includes rotating the engine in the reverse direction without fuel via a motor while injecting DEF into the exhaust manifold. In both the fifth and sixth operating conditions, the EGR valve may be commanded to open. Furthermore, in both the fifth and sixth operating conditions, in response to delivering DEF to the EGR system, the method includes vaporizing the DEF via starting the engine to burn air and fuel to reduce carbon deposits. In the fifth operating condition, one cylinder may be deactivated, while in the sixth operating condition, all cylinders may be started to burn air and fuel. Additionally, in the fifth condition, DEF may be continuously injected into the intake manifold while the engine is burning air and fuel.

[0073] In another instance, where the EGR flow rate is lower than expected or desired when the EGR valve is open, or higher than expected when the EGR valve is closed, an alternative method can be used to clean carbon deposits from the EGR valve (e.g., 253). In some instances, such a method can be used in response to situations where the vehicle is not equipped with a DEF line that allows DEF injection into the intake manifold (e.g., 244), but DEF can be injected into the exhaust manifold (e.g., 335), as in... Figure 2AThe description is as follows. In this example, liquid DEF can be injected into the exhaust manifold and delivered to the EGR passage (e.g., 250) by causing the engine to rotate in reverse without fuel (e.g., without burning air and fuel). More specifically, by rotating the engine in reverse, a vacuum can be created in the exhaust system, while pressure can be created in the intake manifold. For example, when the engine is rotating in reverse, the opening of the cylinder exhaust valve (not shown) allows fresh air (and exhaust gas, if present) to enter the cylinder, and the subsequent opening of the cylinder intake valve (not shown) empties the cylinder into the intake manifold. If the EGR valve (e.g., 253) is open, then liquid DEF can be delivered to the EGR passage. Once liquid DEF is present in the EGR passage, the engine can be started to burn air and fuel, and the engine rotates in the default direction. By operating the engine to burn air and fuel, exhaust heat can be delivered to the EGR passage, where the moisture in the DEF can be vaporized, which can be used to clean carbon deposits from the EGR valve.

[0074] In another example, a method may include: in a seventh operating condition, injecting DEF into the vehicle's exhaust manifold to fill an SCR catalyst positioned in the exhaust manifold with ammonia; and in an eighth operating condition, injecting DEF into the vehicle's engine exhaust manifold to reduce carbon deposits in the EGR system. In this example, the seventh operating condition may include an oxidation catalyst (e.g., 226) positioned upstream of the injection site for injecting DEF into the exhaust manifold, with a temperature above or below a threshold temperature (the threshold temperature includes a temperature above which DEF transported across the oxidation catalyst can vaporize). The eighth operating condition may include a condition in which the temperature of the oxidation catalyst is below the threshold temperature. In this example, the seventh operating condition may include the engine burning air and fuel during DEF injection, while the eighth operating condition may include the engine not burning air and fuel during the injection. Furthermore, the eighth operating condition may include rotating the engine in the reverse direction for a predetermined duration during the injection to transport DEF to the EGR system, and, in response to the elapsed predetermined duration, stopping the engine rotation in the reverse direction and starting the engine to burn air and fuel. In some instances, the engine speed (RPM) may be increased and / or the amount of DEF injected into the exhaust manifold may be increased as the level of condensate stored in the EGR cooler located in the EGR system decreases, or vice versa. Furthermore, the seventh operating condition may be independent of whether the EGR valve is open or closed, while the eighth operating condition may include commanding the EGR valve to open only before (within 2 seconds or less) or in conjunction with the injection of DEF into the exhaust manifold. In some instances, the EGR valve may be commanded to open only after (within 2 seconds or less) the injection of DEF into the exhaust manifold.

[0075] In another example, the ninth operating condition may include a key-on event and an indication of carbon buildup in the EGR system. This ninth operating condition may include commanding the EGR valve to open, operating the first DEF injection valve (e.g., 292) in a duty cycle based on the condensate level in the EGR cooler, and rotating the engine in reverse without fuel (e.g., increasing engine speed and / or increasing injection as condensate levels decrease, or decreasing engine speed and / or decreasing injection as condensate levels increase). Such actions can deliver DEF to the EGR system. After a predetermined duration of this delivery, the ninth operating condition may include stopping the first DEF injection valve from operating, stopping the engine from rotating in reverse without fuel, and starting the engine to burn air and fuel to vaporize the DEF delivered to the EGR system. In the tenth operating condition, the first DEF injection valve may be operated while the engine is burning air and fuel to fill the SCR catalyst with ammonia. The ninth operating condition may include oxidizing the catalyst at a temperature below a threshold temperature, while the tenth operating condition may be independent of the temperature of the oxidizing catalyst.

[0076] In each of the above examples, it can be understood that when the engine is rotating in the forward direction without fuel, the direction can include the default direction or the same direction in which the engine rotates when burning air and fuel. In this case, a vacuum can be created in the engine's intake manifold, while pressure can be generated in the exhaust system. Alternatively, when the engine is rotating in the reverse direction without fuel, a vacuum can be created in the engine's exhaust system, while pressure can be generated in the intake manifold.

[0077] The following will discuss... Figures 4 to 6 The methods described herein are detailed in the exemplary methods mentioned above.

[0078] As discussed above, the exemplary methods mentioned above may include rotating the engine in a forward (e.g., default) or reverse direction without fuel. To enable the engine to rotate in a forward or reverse direction without fuel, a vehicle motor (e.g., 120) using electricity supplied via an energy storage device (e.g., 150) (e.g., a battery) may be employed.

[0079] Therefore, turning Figures 3A to 3BThese illustrate an exemplary circuit 300 that can be used to reverse the rotational orientation of an electric motor. Circuit 300 schematically depicts an H-bridge circuit that can be used to operate a motor 310 in a first (forward) direction and alternatively in a second (reverse) direction. Circuit 300 includes a first (LO) side 320 and a second (HI) side 330. Side 320 includes transistors 321 and 322, while side 330 includes transistors 331 and 332. Circuit 300 also includes a power supply 340.

[0080] exist Figure 3A In this configuration, transistors 321 and 332 are activated (energized), while transistors 322 and 331 are deactivated. In this configuration, the left lead 351 of motor 310 is connected to power supply 340, and the right lead 352 of motor 310 is grounded. In this way, motor 300 can operate in the forward direction. When the engine is operated in the forward direction via the motor, the engine can be in a rotation-start mode where initial combustion begins. Additionally and / or alternatively, when the engine is operated in the forward direction via the motor, the engine (and the motor or another motor) can be in a drive mode for driving the vehicle. It is understood that in some instances, the engine can rotate in the forward (e.g., default) direction while the vehicle is stationary, and it is desirable for the engine to rotate or turn in the forward direction without combustion.

[0081] exist Figure 3B In this configuration, transistors 322 and 331 are activated (energized), while transistors 321 and 332 are deactivated. In this configuration, the right lead 352 of motor 310 is connected to power supply 340, and the left lead 351 of motor 310 is grounded. In this way, motor 310 can run in the reverse direction.

[0082] Turn now Figure 4 This diagram illustrates a high-level flowchart of an exemplary method 400 for performing a procedure to remove carbon deposits from one or more cylinders of a vehicle engine. More specifically, method 400 may include injecting diesel exhaust fluid (DEF) into the engine's intake manifold while the engine is burning air and fuel. The DEF injected into the intake manifold can thus be drawn into the engine, where the water component of the DEF can be vaporized, thereby cleaning the carbon deposits.

[0083] References will be made to the description in this article and Figures 1 to 3B The system shown is used to describe method 400, but it should be understood that similar methods can be applied to other systems without departing from the scope of this disclosure. Method 400 can be provided by a controller, such as... Figures 2A to 2BThe controller 212 executes the instructions, which can be stored at the controller as executable instructions in non-transitory memory. Instructions for implementing method 400 and the remainder of the methods included herein can be executed by the controller based on instructions stored in the controller's memory and in conjunction with signals received from sensors of the engine system, such as those referenced above. Figure 1 and Figures 2A to 2B The sensor described herein. According to the method described below, the controller may employ actuators of a vehicle system, such as a second DEF injection valve (e.g., 296), a motor (e.g., 120), a fuel injector (e.g., 266), an intake throttle valve (e.g., 262), etc.

[0084] Method 400 begins at 402 and may include estimating and / or measuring current operating conditions. Operating conditions may be estimated, measured, and / or inferred, and these operating conditions may include: one or more vehicle conditions, such as vehicle speed, vehicle position, etc.; various engine conditions, such as engine status, engine load, engine speed, A / F ratio, etc.; various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc.; various evaporative emission system conditions, such as fuel vapor filter load, fuel tank pressure, etc.; and various environmental conditions, such as ambient temperature, humidity, air pressure, etc.

[0085] Proceeding to 404, method 400 may include an indication of whether conditions for performing a cylinder decarbonization diagnostic procedure are met. Meeting the conditions for performing the cylinder decarbonization diagnostic procedure may include an on-board dynamic balancing test that has indicated sluggish engine performance, thereby (e.g.) indicating that carbon deposits have accumulated in one or more engine cylinders. Meeting the conditions at 404 may additionally or alternatively include a cylinder compression test that has indicated sluggish engine performance. Meeting the conditions at 404 may, in some instances, include a cutoff condition where sluggish engine performance has been indicated via a dynamic balancing test and / or a cylinder compression test. Meeting the conditions at 404 may additionally or alternatively include a threshold duration (e.g., 1 day, 2 days, 5 days, 10 days, or greater than 10 days but less than 30 days) since a previous cylinder decarbonization diagnostic. Meeting the conditions at 404 may additionally or alternatively include an indication that the level of DEF in a DEF reservoir (e.g., 241) is greater than a predetermined threshold (e.g., a full >10%, >20%, or >30%). At 404, if the indication does not meet the conditions for performing cylinder decarbonization diagnostics, then method 400 may proceed to 406. At 406, method 400 may include maintaining current vehicle operating parameters. For example, if the vehicle is in operation with the engine running and no shutdown event is indicated, then the current engine operating parameters may be maintained. In another instance, if the vehicle is propelled at least partially by electrical energy obtained from an onboard energy storage device, then electric operation may be maintained. Such examples are illustrative. Method 400 may then terminate.

[0086] Returning to 404, if the indication meets the conditions for performing cylinder decarbonization diagnostics, then method 400 can proceed to 408. At 408, method 400 may include commanding or maintaining engine combustion of air and fuel. For example, if the vehicle is operating in a pure electric mode when disconnected, and the indication meets the conditions for performing cylinder decarbonization diagnostics, then at 408 the engine can be started or pulled up to begin combustion of air and fuel. If the engine is already burning air and fuel, then combustion can be maintained at step 408. Furthermore, at 408, the engine speed can be controlled to a desired engine speed. This desired engine speed can be achieved via a controller (e.g., 212) that commands engine system actuators such as fuel injector (e.g., 266), throttle position (e.g., 262), etc., to control the engine speed to the desired speed. Additionally, at 408, method 400 may include keeping the controller awake so that the cylinder decarbonization procedure can be performed.

[0087] Moving to 410, method 400 may include cyclically operating a second DEF injector valve (e.g., 296). Specifically, by cyclically operating the second DEF injector valve, DEF fluid can be drawn from a DEF reservoir (e.g., 239) and drawn into the intake manifold (e.g., 244) of an engine (e.g., 110). DEF fluid can be drawn from the DEF reservoir due to engine vacuum, which can be generated by operating the engine in a default direction (e.g., forward direction). It is understood that cyclically operating the second DEF injector valve may include: a controller sending a signal to the second DEF injector valve; commanding or actuating the second DEF injector valve to open and close. The second DEF injector valve may be cyclically operated in such a way that the amount of DEF injected into the intake manifold each time the second DEF injector valve is opened is less than a threshold amount of fuel injected into an individual engine cylinder each time fuel is injected. For example, the threshold quantity may include DEF being 3 times less than fuel, DEF being between 3 times and 10 times less than fuel, DEF being between 10 times and 100 times less than fuel, or DEF being more than 100 times less than fuel.

[0088] Moving to 412, method 400 may include monitoring engine speed. Engine speed may be monitored, for example, via an engine speed sensor (e.g., 265). Engine speed may be monitored while the engine is burning air and fuel and while DEF is being injected into the intake manifold. Moving to 414, method 400 may include indicating whether the engine speed has decreased below a threshold engine speed. The threshold engine speed may include, for example, an engine speed slightly above the engine stall speed (e.g., 100 RPM, 200 RPM, or 500 RPM higher). At 414, if the indicated engine speed has decreased below the threshold engine speed, then method 400 may proceed to 416 and may include increasing the engine speed above the threshold engine speed to a desired engine speed (as discussed above at step 408 of method 400). More specifically, the throttle (e.g., 262) may be commanded to a more open position, thereby allowing more intake airflow to reach the engine, which may allow for the increased engine speed. In some instances, fuel injection into one or more engine cylinders may be increased, either additionally or alternatively, thereby increasing the engine speed to the desired engine speed.

[0089] If the engine speed is not indicated to be below a threshold engine speed at step 414, or if the engine system actuators have already controlled the engine speed to the desired engine speed at 416, then method 400 may proceed to 418. At 418, method 400 may include an indication of whether carbon deposits have been removed from the engine cylinders. Such an indication may be provided via the on-board dynamic balancing test discussed above. In other words, the controller may run the on-board dynamic balancing test while starting the engine to burn air and fuel, while injecting DEF into the intake manifold, and while controlling the engine speed to the desired engine speed. In the case of injecting DEF into the intake manifold, DEF can be drawn into the engine cylinders, and when fuel is ignited in the engine cylinders, the water component of the DEF can vaporize into steam, which can effectively clean (e.g., decarbonize) the engine cylinders. Therefore, the on-board dynamic balancing test can be used to indicate whether the engine cylinders have been effectively cleaned. More specifically, the dynamic balancing test may include measuring engine torque via a torque sensor (e.g., 267). The dynamic balance test can indicate that one or more engine cylinders are not operating as required (e.g., the torque produced by a particular cylinder is lower than the torque produced via another engine cylinder). Therefore, at 418, in response to one or more engine cylinders still not operating as required, method 400 can proceed to 419 and may include indicating whether a predetermined duration has elapsed. For example, if carbon deposits are the cause of sluggish engine performance (e.g., one or more engine cylinders not operating as required), the predetermined duration may include the expected duration for removing carbon deposits from one or more engine cylinders. The predetermined duration may include, for example, one minute, between one and two minutes, between two and three minutes, between three and five minutes, or more than five minutes. At 419, if the predetermined duration has not yet elapsed, then method 400 can return to 408 and may include continuing to operate the engine to burn air and fuel while injecting DEF into the intake manifold.

[0090] Alternatively, at 419, if the predetermined duration has elapsed, then method 400 can proceed to 421 and may include instructing the engine to degrade. More specifically, a flag can be set at the controller indicating that a cylinder decarbonization test diagnostic has been performed and that the test diagnostic cannot correct problems related to one or more engine cylinders not operating as required. Furthermore, a malfunction indicator lamp (MIL) on the vehicle's dashboard can be illuminated to warn the vehicle operator that the vehicle needs maintenance.

[0091] Moving to 423, method 400 may include stopping the second DEF injection valve from operating cycle. Upon command or actuation of the second DEF injection valve via a controller, the engine intake manifold vacuum may therefore no longer draw DEF into the intake manifold. Moving to 425, the engine may be deactivated or shut down. For example, fuel injection may be commanded / actuated to stop via a controller that sends a signal to the fuel injectors (e.g., 266), and the spark supplied to individual engine cylinders may be interrupted (if the engine includes spark plugs for supplying spark to individual cylinders).

[0092] Moving forward to 427, method 400 may include updating vehicle operating parameters. For example, vehicle operating parameters may be adjusted / updated to compensate for indicated engine degradation. In an instance where the vehicle system includes a hybrid electric vehicle capable of operating in pure electric mode, the vehicle may be commanded to operate in pure electric mode as frequently as possible to avoid further engine degradation.

[0093] Proceeding to 429, method 400 may include putting the controller to sleep because the cylinder decarburization diagnostic routine has ended. Method 400 may then terminate.

[0094] Returning to 418, in response to an indication that carbon deposits have been removed from the engine cylinders (indicated via an on-board dynamic balancing test), method 400 can proceed to 431. More specifically, the dynamic balancing test can indicate that carbon deposits have been removed from the engine cylinders in response to torque generation in all engine cylinders being within a threshold of desired or anticipated torque generation (e.g., within 5%). Desired or anticipated torque generation can include the torque level generated at a specific engine speed (e.g., RPM) where no carbon deposits are present at the engine cylinders. At 431, method 400 can include stopping the second DEF injection valve from operating cycles. Upon command or actuation of the second DEF injection valve via the controller, the engine intake manifold vacuum can therefore no longer draw DEF into the intake manifold. Proceeding to 433, the engine can be deactivated or shut down. For example, fuel injection can be commanded / actuated to stop via a controller that sends a signal to the fuel injector (e.g., 266), and the spark supplied to individual engine cylinders can be interrupted (if the engine includes spark plugs for supplying sparks to individual cylinders).

[0095] Moving to 435, method 400 may include updating vehicle operating parameters. For example, vehicle operating parameters may be adjusted / updated to compensate for indicated carbon-free deposits on the cylinders. A flag may be set at the controller to indicate that a cylinder decarbonization test diagnostic has been performed and that engine cylinder torque production has been successfully restored to the desired or anticipated torque production.

[0096] Proceeding to 437, method 400 may include putting the controller to sleep because the cylinder decarburization diagnostic routine has ended. Method 400 may then terminate.

[0097] While the exemplary method 400 described above depicts a method for removing carbon deposits from one or more engine cylinders in an on-board and on-demand manner, in some instances other engine components may be present that could benefit from decarbonization technologies or methods. Specifically, an EGR system (e.g., 249) can recirculate exhaust gas back into the intake system, thereby reducing nitrogen oxide (NOx) emissions. Over time, soot and other carbonaceous materials may accumulate on the EGR system and may clog it or cause the EGR valve (e.g., 253) to become stuck open or stuck closed. Therefore, a method for cleaning carbon deposits from an EGR system (e.g., 249) is desirable, similar to the methods discussed above for cleaning carbon deposits from one or more engine cylinders.

[0098] Therefore, now turn to Figure 5 This diagram illustrates a high-level flowchart of an exemplary method 500 for performing a procedure to remove carbon deposits from an EGR system. More specifically, method 500 may include injecting DEF into the engine's intake manifold (e.g., 244) while the engine is rotating in the forward or default direction and with the EGR valve open, thereby delivering DEF into the EGR passage. After a predetermined duration of delivering DEF into the EGR passage, the engine may be started to burn air and fuel, with one cylinder deactivated (not receiving fuel injection). DEF can thus be continuously delivered to the EGR passage, and the heat from combustion can evaporate the water component of the DEF into steam, which can effectively clean the carbon deposits in the EGR passage. Importantly, such methods include on-board and on-demand EGR cleaning methods.

[0099] References will be made to the description in this article and Figures 1 to 3B The system illustrated herein is used to describe method 500, but it should be understood that similar methods can be applied to other systems without departing from the scope of this disclosure. Method 500 can be provided by a controller, such as... Figures 2A to 2B The controller 212 executes the instructions, which can be stored at the controller as executable instructions in non-transitory memory. Instructions for implementing method 500 and the remainder of the methods included herein can be executed by the controller based on instructions stored in the controller's memory and in conjunction with signals received from sensors of the engine system, such as those referenced above. Figure 1 and Figures 2A to 2BThe sensor described herein. According to the method described below, the controller may employ actuators of a vehicle system, such as a second DEF injection valve (e.g., 296), a motor (e.g., 120), a fuel injector (e.g., 266), an intake throttle valve (e.g., 262), an EGR valve (e.g., 253), etc.

[0100] Method 500 begins at 502 and may include estimating and / or measuring current vehicle operating conditions. Operating conditions may be estimated, measured, and / or inferred, and these operating conditions may include: one or more vehicle conditions, such as vehicle speed, vehicle position, etc.; various engine conditions, such as engine status, engine load, engine speed, A / F ratio, etc.; various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc.; various evaporative emission system conditions, such as fuel vapor filter load, fuel tank pressure, etc.; and various environmental conditions, such as ambient temperature, humidity, air pressure, etc.

[0101] Proceeding to 504, method 500 may include an indication of whether conditions for performing EGR cleaning diagnostics are met. Meeting the conditions for performing EGR cleaning diagnostics may include an indication of low EGR flow monitored via a pressure sensor (e.g., 256) in the EGR passage (e.g., 250). For example, the expected amount of EGR flow in the absence of carbon deposits associated with the EGR valve and / or in the EGR passage may be stored at the controller in the form of a lookup table, the expected amount including expected flow rates under various engine speeds and / or other operating conditions. Low EGR flow may include an EGR flow level that differs from the expected EGR flow under specific engine operating conditions by a threshold, such as more than 5% or more than 10%. In another instance, meeting the conditions for performing EGR cleaning diagnostics may include an indication of a degraded EGR system demonstrated by, for example, approximately idling or, in some instances, stall conditions.

[0102] The condition to be met may additionally or alternatively include a cut-off condition, indicating a low flow rate in the EGR channel, or indicating an EGR system degradation. In some instances, the condition to be met at 504 may additionally or alternatively include an indication of a threshold duration (e.g., 1 day, 2 days, 5 days, 10 days, 15 days, greater than 20 days but less than 30 days, etc.) since the previous EGR cleaning diagnostic. The condition to be met at 504 may additionally or alternatively include an indication that the amount of DEF stored in the DEF container (e.g., 241) is greater than a predetermined threshold (e.g., a full >10%, >20%, or >30%).

[0103] At 504, if no conditions for performing EGR cleaning diagnostics are indicated, then method 500 may proceed to 506. At 506, method 500 may include maintaining the current vehicle operating parameters. For example, if the vehicle is operating with the engine running, such operation may be maintained. Alternatively, if the vehicle is operating where it is fully or partially propelled by electricity, such operating conditions may continue. Method 500 may then terminate.

[0104] Returning to 504, in response to an indication that conditions for performing EGR cleaning diagnostics are met, method 500 may proceed to 507. At 507, method 500 may include commanding the EGR valve (e.g., 253) to open. For example, the controller may send a signal to the EGR valve, thereby actuating the EGR valve to open. Proceeding to 508, method 500 may include rotating the engine in a default or forward direction without fuel. Specifically, the controller may command a motor (e.g., 120) to rotate or turn the engine in the default direction without fuel. In some instances, rotating the engine without fuel may include rotating the engine at a predetermined engine speed (engine RPM) without fuel.

[0105] Proceeding to 510, method 500 may include circumventing a second DEF injection valve (e.g., 296). Circumventing a second DEF injection valve may include circumventing the second DEF injection valve for a predetermined duration to add a predetermined amount of DEF. Therefore, proceeding to 512, method 500 may include indicating whether the predetermined duration has elapsed. If the predetermined duration has not elapsed, then method 500 may return to 508 and may include continuing to rotate the engine in the default direction without fuel, and may also include continuing to circumvent the second DEF injection valve. Alternatively, in response to the predetermined duration elapsed at 512, method 500 may proceed to 514.

[0106] It is understood that by injecting DEF into the intake manifold via the second DEF injection valve and by turning the engine without fuel while the EGR valve is open, DEF can be drawn through the engine and into the EGR passage (e.g., 250).

[0107] At 514, method 500 may include starting the engine to burn air and fuel. For example, the motor may be deactivated, and fuel injection (and spark (if the engine includes spark plugs for providing spark to individual cylinders)) may be provided to the engine cylinders. The fuel (and spark (if applicable)) may be controlled via a controller to control the engine speed to a desired speed. Furthermore, at 514, starting the engine to burn air and fuel may include providing fuel (and spark (if applicable)) to all engine cylinders except one. Cylinders that do not receive fuel (and spark (if applicable)) may be referred to as deactivated cylinders, but it is understood that while the engine is additionally burning air and fuel, said deactivated cylinders are still used to open the intake and exhaust valves associated with them. Furthermore, at 514, the spark provided to all cylinders except the deactivated cylinders may include a delayed spark, which, compared to a non-delayed spark, can be used to increase the amount of heat delivered to the exhaust manifold and EGR passages. However, it is understood that in diesel vehicles, a spark may not be provided. It can be further understood that the deactivated cylinder may include a route for the DEF (besides the DEF already delivered to the EGR passage for vaporization) to be sent to the EGR passage. Furthermore, although not explicitly shown, the exhaust tuning valve (e.g., 299) may be controlled to a position where heat from the engine is effectively delivered to the EGR passage. For example, in some instances, the exhaust tuning valve may be controlled to be fully closed, or it may be mostly closed (e.g., open 20% or less), such that heat exhausted from the engine is delivered to the EGR passage.

[0108] Therefore, proceeding to 516, method 500 may include maintaining a second DEF injection valve duty cycle. In some instances, the second DEF injection valve duty cycle at 516 may include the same second DEF injection valve duty cycle rate as performed at step 510 of method 500. In other instances, maintaining a second DEF injection valve duty cycle at 516 may include maintaining the second DEF injection valve duty cycle at a rate greater than or less than the duty cycle rate performed at 510. As discussed, in the case of deactivating a cylinder, DEF can be delivered to the exhaust manifold and EGR passage for vaporization. The vaporization of DEF can thus convert the water component of DEF into steam, which can be used to clean any deposits in and / or associated with the EGR valve in the EGR passage.

[0109] Moving to 518, method 500 may include maintaining the engine speed at a desired engine speed. For example, when DEF is injected into the intake manifold, even if there are deactivated cylinders that could deliver DEF to the exhaust manifold and EGR passage, additional DEF may be introduced into the combustion cylinders, which in some instances may cause a drop in engine speed. Therefore, to prevent potential stall conditions, the engine speed can be maintained at a desired speed by controlling the position of the throttle (e.g., 262). For example, in response to a drop in engine RPM, the throttle can be commanded to a more open position, thereby allowing additional air to be drawn into the intake manifold, thus controlling the engine speed to the desired engine speed. Furthermore, at 518, method 500 may include controlling the engine to maintain a desired engine intake manifold vacuum, thereby allowing DEF to be drawn through the engine to the exhaust manifold and EGR passage. To maintain the desired engine intake manifold vacuum, fuel injection, throttle position, spark (where applicable), etc., can be controlled to maintain the desired intake manifold vacuum.

[0110] Moving forward to 520, method 500 may include indicating whether carbon deposits have been removed from the EGR valve and / or EGR passage. Specifically, at 520, method 500 may include monitoring the pressure in the EGR passage and indicating whether the EGR flow rate under a specific engine operating condition (e.g., a desired engine speed) is within a threshold (e.g., within 5%) of the expected EGR flow rate (e.g., a condition where there are no carbon deposits in the EGR passage and / or associated with the EGR valve). As discussed above, a lookup table stored at the controller may include the expected EGR flow rate, which varies with engine operating conditions, and accordingly, such a lookup table may be queried at 520 via the controller to indicate whether carbon deposits have been removed from the EGR valve / EGR passage.

[0111] At 520, if the EGR flow rate is indicated to be within the expected EGR flow rate threshold after carbon deposits have been removed, then method 500 can proceed to 522. In other words, method 500 can proceed to 522 in response to an indication that carbon deposits have been removed. At 522, method 500 may include commanding the EGR valve to the closed position, and may also include stopping the injection of DEF into the intake manifold. More specifically, the second DEF injection valve may be commanded to close, thereby stopping the second DEF injection valve's operating cycle and ceasing the injection of DEF into the intake manifold.

[0112] Moving to 524, method 500 may include maintaining the engine at a desired engine speed for a predetermined duration. Specifically, the engine may be maintained in operation of burning air and fuel to force any removed carbon deposits out of the exhaust manifold. Furthermore, all engine cylinders may be activated to burn air and fuel. In other words, fuel (and spark (where applicable)) may be supplied to the deactivated cylinder, causing all engine cylinders to burn air and fuel. Thus, deposits may be transported to the exhaust manifold and not to the EGR passage, because the EGR valve is commanded to close at step 522. At 524, the predetermined duration may include the duration for which any carbon deposits removed from the EGR passage and / or EGR valve are expected to be transported out of the exhaust manifold. In some instances, the predetermined duration at 524 may include 1 minute, 2 minutes, 3 minutes, 4 minutes, or 5 minutes.

[0113] Proceeding to 526, method 500 may include stopping or deactivating the engine after an indication (of 524) that a predetermined duration has elapsed. For example, fuel supply to the engine cylinders (and spark (where applicable)) may be stopped, and the engine may stop rotating. At 528, method 500 may include updating vehicle operating parameters. Specifically, vehicle operating parameters may be updated to reflect an indication that the EGR valve and EGR passage are now clean or free of carbon deposits. Furthermore, at 528, updating vehicle operating parameters may include setting a flag at the controller indicating that an EGR cleaning routine has been performed and that the routine has successfully removed carbon deposits from the EGR valve and / or EGR passage. In some instances, in response to the completion of the EGR cleaning routine, method 500 may include putting the controller to sleep. Method 500 may then terminate.

[0114] Returning to 520, in response to an indication that carbon deposits have not been removed from the EGR valve and / or EGR passage, method 500 may proceed to 530. At 530, method 500 may include indicating whether a predetermined duration has elapsed. The predetermined duration at 530 may include a duration in which, if the carbon deposits associated with the EGR valve and / or EGR passage are the culprit causing low EGR flow, then it can be expected that such deposits have been removed via the EGR cleaning routine of method 500. Therefore, at 530, if it is indicated that the predetermined duration has not elapsed, method 500 may return to 514 and may include continuing to operate the engine at a desired speed with one cylinder deactivated and DEF injected via a second DEF injection valve working cycle while the engine is burning air and fuel, until it is indicated that the carbon deposits have been removed or the predetermined duration has elapsed. Therefore, at 530, in response to an indication that the predetermined duration has elapsed, method 500 may proceed to 532. At 532, method 500 may include instructing the EGR system to degrade. For example, because the routine of method 500 fails to restore the flow in the EGR system to the expected flow, it may indicate a root cause for which the low flow cannot be remedied by the routine of method 500. Therefore, instructing the EGR system to degrade at 532 may include setting a malfunction indicator lamp (MIL) on the vehicle dashboard to warn the vehicle operator of a request for vehicle maintenance. Additionally, a flag may be set on the controller indicating that the EGR cleaning routine of method 500 was executed but failed to restore the EGR flow to the expected EGR flow.

[0115] After determining that the EGR system has degraded, method 500 can proceed to 522. Steps 522 through 528 are performed in the same manner, regardless of whether EGR system degrade is indicated or whether carbon deposits are indicated to be removed from the EGR valve and / or EGR passage. For example, even if EGR system degrade is indicated, the routine of method 500 may still result in the removal of some carbon deposits from the EGR valve and / or EGR passage. Therefore, at 524, the engine can be kept running for a predetermined duration with the EGR valve closed and the second DEF injection valve closed. At 528, updating the vehicle operating parameters in light of the indicated EGR system degrade may include operating the engine in a manner that avoids the use of EGR until the degrade has been remedied. In some instances where the vehicle includes a hybrid vehicle, the vehicle may be operated as frequently as possible in pure electric mode or hybrid operating mode to avoid using the engine and EGR passage. Furthermore, at 528, in response to completing the routine, method 500 may include putting the controller to sleep. Method 500 may then terminate.

[0116] The important thing is that it is understandable. Figure 5 The EGR cleaning methods provide on-board and on-demand EGR channel / EGR valve cleaning methods.

[0117] Although Figure 5 The method described above involves cleaning the EGR valve and / or EGR passage by injecting DEF into the intake manifold. However, situations may exist where injecting DEF into the intake manifold is undesirable, or in some instances, the vehicle may not be equipped with a DEF injection line reaching the intake manifold. Therefore, different methods can be used, which may include injecting DEF into the exhaust system. Figure 6 This method will be discussed in detail here.

[0118] Therefore, now turn to Figure 6 This paper illustrates an advanced exemplary method 600 for performing an EGR cleaning routine, wherein DEF is injected into the exhaust manifold of a vehicle. More specifically, such a method can be performed in response to a request to clean the EGR passage and / or the EGR valve, and the method may include injecting DEF into the exhaust manifold to deliver DEF into the EGR passage when the EGR valve is open and the engine is running in reverse without fuel. Subsequently, the engine can be started to burn air and fuel to transfer combustion heat to the EGR passage, which can vaporize the DEF, thereby converting the water component into steam, which can lead to the removal of carbon deposits associated with the EGR valve and / or the EGR passage. In this way, the EGR passage can be cleaned efficiently both on-board and on demand.

[0119] References will be made to the description in this article and Figures 1 to 3B The system shown herein is used to describe method 600, but it should be understood that similar methods can be applied to other systems without departing from the scope of this disclosure. Method 600 can be provided by a controller, such as... Figures 2A to 2B The controller 212 executes the instructions, which can be stored at the controller as executable instructions in non-transitory memory. Instructions for implementing method 600 and the remainder of the methods included herein can be executed by the controller based on instructions stored in the controller's memory and in conjunction with signals received from sensors of the engine system, such as those referenced above. Figure 1 and Figures 2A to 2B The sensor described herein. According to the method described below, the controller may employ actuators of a vehicle system, such as a first DEF injection valve (e.g., 292), a motor (e.g., 120), a fuel injector (e.g., 266), an intake throttle valve (e.g., 262), an EGR valve (e.g., 253), etc.

[0120] Method 600 begins at 602 and may include estimating and / or measuring current vehicle operating conditions. Operating conditions may be estimated, measured, and / or inferred, and these operating conditions may include: one or more vehicle conditions, such as vehicle speed, vehicle position, etc.; various engine conditions, such as engine status, engine load, engine speed, A / F ratio, etc.; various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc.; various evaporative emission system conditions, such as fuel vapor filter load, fuel tank pressure, etc.; and various environmental conditions, such as ambient temperature, humidity, air pressure, etc.

[0121] Moving to 604, method 600 may include an indication of whether conditions for performing EGR cleaning diagnostics are met. Meeting the conditions for performing EGR cleaning diagnostics may include an indication of low EGR flow monitored via a pressure sensor (e.g., 256) in the EGR passage (e.g., 250). For example, the expected amount of EGR flow in the absence of carbon deposits associated with the EGR valve and / or in the EGR passage may be stored at the controller in the form of a lookup table, the expected amount including expected flow rates under various engine speeds and / or other operating conditions. Low EGR flow may include an EGR flow level that differs from the expected EGR flow under specific engine operating conditions by a threshold, such as more than 5% or more than 10%. In another instance, meeting the conditions for performing EGR cleaning diagnostics may include an indication of a degraded EGR system demonstrated by, for example, approximately idling or, in some instances, by stall conditions.

[0122] The fulfillment of the condition may additionally or alternatively include a key-on event indicating a low flow rate in the EGR channel, or indicating EGR system degradation. The fulfillment of the condition may also include an indication that the temperature of the oxidation catalyst (e.g., 226) is below a threshold temperature. In some instances, fulfilling the condition at 604 may additionally or alternatively include an indication of the threshold duration (e.g., 1 day, 2 days, 5 days, 10 days, 15 days, greater than 20 days but less than 30 days, etc.) that has elapsed since the previous EGR cleaning diagnostic. Fulfilling the condition at 604 may additionally or alternatively include an indication that the amount of DEF stored in the DEF tank (e.g., 241) is greater than a predetermined threshold (e.g., a full >10%, >20%, or >30%).

[0123] At 604, if no conditions for performing EGR cleaning diagnostics are indicated, then method 600 may proceed to 606. At 606, method 600 may include maintaining current vehicle operating parameters. For example, if the vehicle is operating with the engine running, such operation may be maintained. Alternatively, if the vehicle is operating where it is propelled entirely or partially by electric power, such operating conditions may continue. Method 600 may then terminate.

[0124] Returning to 604, in response to an indication that conditions for performing EGR cleaning diagnostics are met, method 600 may proceed to 607. At 607, method 600 may include commanding the EGR valve (e.g., 253) to open. For example, the controller may send a signal to the EGR valve, thereby actuating the EGR valve to open. Proceeding to 608, method 600 may include rotating the engine in the reverse direction without fuel. Specifically, the controller may command a motor (e.g., 120) to rotate or turn the engine in the reverse direction without fuel. In some instances, rotating the engine without fuel may include rotating the engine at a predetermined engine speed (engine RPM) without fuel.

[0125] Proceeding to 610, method 600 may include circumventing a first DEF injection valve (e.g., 292). Circumventing the first DEF injection valve may include circumventing the first DEF injection valve to inject a predetermined amount of DEF into the exhaust manifold for a predetermined duration. Therefore, proceeding to 612, method 600 may include indicating whether the predetermined duration has elapsed. If the predetermined duration has not elapsed, then method 600 may return to 608 and may include continuing to rotate the engine in the reverse direction without fuel, and may also include continuing to circumvent the first DEF injection valve. Alternatively, in response to the predetermined duration elapsed at 612, method 600 may proceed to 614.

[0126] It can be understood that by injecting DEF into the exhaust manifold via the first DEF injection valve and by rotating the engine in reverse without fuel when the EGR valve is open, DEF can be drawn through the engine and into the EGR passage (e.g., 250).

[0127] At 614, in response to the elapsed duration of a predetermined time, method 600 may include stopping the engine from rotating in the reverse direction and starting the engine to burn air and fuel. For example, the motor may be deactivated and, in this instance, the engine may stop rotating and then be started to burn air and fuel. It is understood that when the engine is started to burn air and fuel, the engine rotates or spins in the default or forward direction. Furthermore, at 614, method 600 may include stopping the first DEF injection valve from operating cycle. Fuel (and spark (where applicable)) may be controlled via a controller to control the engine speed to a desired speed. Furthermore, although not explicitly shown, an exhaust tuning valve (e.g., 299) may be controlled to a position where heat from the engine is effectively transported to the EGR passage. For example, in some instances, the exhaust tuning valve may be controlled to a fully closed configuration, or it may be mostly closed (e.g., open 20% or less), such that heat exhausted from the engine is transported to the EGR passage.

[0128] Therefore, moving forward to 616, method 600 may include maintaining the engine speed at a desired engine speed. For example, the engine speed may be maintained at the desired speed by controlling the position of the throttle valve (e.g., 262). For example, in response to a decrease in engine RPM, the throttle valve may be commanded to a more open position, thereby allowing additional air to be drawn into the intake manifold, thereby controlling the engine speed to the desired engine speed. The desired engine speed may include the engine speed at which heat from the combustion engine is expected to vaporize the DEF transported to the EGR passage.

[0129] Moving to 618, method 600 may include indicating whether carbon deposits have been removed from the EGR valve and / or EGR passage. Specifically, at 618, method 600 may include monitoring the pressure in the EGR passage and indicating whether the EGR flow rate under a specific engine operating condition (e.g., a desired engine speed) is within a threshold (e.g., within 5%) of the expected EGR flow rate (e.g., a condition where there are no carbon deposits in the EGR passage and / or associated with the EGR valve). As discussed above, a lookup table stored at the controller may include the expected EGR flow rate, which varies with engine operating conditions, and accordingly, such a lookup table may be queried at 618 via the controller to indicate whether carbon deposits have been removed from the EGR valve / EGR passage.

[0130] At 618, if the EGR flow rate is indicated to be within the expected EGR flow rate threshold after carbon deposits have been removed, then method 600 can proceed to 620. In other words, method 600 can proceed to 620 in response to an indication that carbon deposits have been removed. At 620, method 600 may include commanding the EGR valve to the closed position.

[0131] Moving to 622, method 600 may include maintaining the engine at a desired engine speed for a predetermined duration. Specifically, the engine may be kept in operation of burning air and fuel to force any removed carbon deposits out of the exhaust manifold. The deposits may be transported to the exhaust manifold but not to the EGR passage because the EGR valve is commanded to close at step 620. At 622, the predetermined duration may include the duration for which any carbon deposits removed from the EGR passage and / or EGR valve are expected to be transported out of the exhaust manifold. In some instances, the predetermined duration at 622 may include 1 minute, 2 minutes, 3 minutes, 4 minutes, or 5 minutes.

[0132] Proceeding to 624, method 600 may include stopping or deactivating the engine after an indication (of 622) that a predetermined duration has elapsed. For example, fuel supply to the engine cylinders (and spark (where applicable)) may be stopped, and the engine may stop rotating. At 628, method 600 may include updating vehicle operating parameters. Specifically, vehicle operating parameters may be updated to reflect an indication that the EGR valve and EGR passage are now clean or free of carbon deposits. Furthermore, at 628, updating vehicle operating parameters may include setting a flag at the controller indicating that an EGR cleaning routine has been performed and that the routine has successfully removed carbon deposits from the EGR valve and / or EGR passage. In some instances, in response to the completion of the EGR cleaning routine, method 600 may include putting the controller to sleep. Method 600 may then terminate.

[0133] Returning to 618, in response to an indication that carbon deposits have not been removed from the EGR valve and / or EGR passage, method 600 may proceed to 630. At 630, method 600 may include indicating whether a predetermined duration has elapsed. The predetermined duration at 630 may include a duration in which, if the carbon deposits associated with the EGR valve and / or EGR passage are the culprit causing low EGR flow, then it can be expected that such deposits have been removed via the EGR cleaning routine of method 600. Therefore, at 630, if it is indicated that the predetermined duration has not elapsed, method 600 may return to 614 and may include continuing to operate the engine at a desired speed while burning air and fuel until it is indicated that the carbon deposits have been removed or the predetermined duration has elapsed. Therefore, at 630, in response to an indication that the predetermined duration has elapsed, method 600 may proceed to 632. At 632, method 600 may include indicating that the EGR system degrades. For example, because the routine of method 600 fails to restore the flow in the EGR system to the expected flow, it can indicate a root cause for which the low flow cannot be remedied by the routine of method 600. Therefore, indicating EGR system degradation at 632 could include setting a malfunction indicator lamp (MIL) on the vehicle's dashboard to warn the vehicle operator of a request for vehicle maintenance. Additionally, a flag can be set on the controller indicating that the EGR cleaning routine of method 600 was executed but failed to restore the EGR flow to the expected EGR flow.

[0134] After determining that the EGR system has degraded, method 600 can proceed to 620. Steps 620 through 628 are performed in the same manner, regardless of whether EGR system degrade is indicated or whether carbon deposits are removed from the EGR valve and / or EGR passage. For example, even if EGR system degrade is indicated, the routine of method 600 may still result in the removal of some carbon deposits from the EGR valve and / or EGR passage. Therefore, at 624, the engine can be kept running for a predetermined duration with the EGR valve closed and the first DEF injection valve closed. At 628, updating the vehicle operating parameters in light of the indicated EGR system degrade may include operating the engine in a manner that avoids using EGR until the degrade is indicated to have been remedied. In some instances where the vehicle includes a hybrid vehicle, the vehicle may be operated as frequently as possible in pure electric mode or hybrid operating mode to avoid using the engine and EGR passage. Furthermore, at 628, in response to completing the routine, method 600 may include putting the controller to sleep. Method 600 may then terminate.

[0135] The important thing is that it is understandable. Figure 6The EGR cleaning methods provide on-board and on-demand EGR channel / EGR valve cleaning methods.

[0136] Turn now Figure 7 This illustrates an exemplary timeline 700 for performing a procedure to remove carbon deposits from one or more cylinders of a vehicle engine. Specifically, exemplary timeline 700 illustrates how the vehicle system can perform procedures according to... Figure 4 The procedure described in the method is as follows. Timeline 700 includes graph 705, which indicates whether conditions for performing cylinder cleaning operations are met. Timeline 700 also includes graph 710, which indicates the state of the engine over time. The engine may start or stop over time. Timeline 700 also includes graph 715, which indicates whether fuel is injected into the engine cylinders over time. Fuel injection may be turned on or off at any time. In this exemplary timeline 700, it can be understood that fuel injection includes fuel injection for all engine cylinders. Timeline 700 also includes graph 720, which indicates whether a second DEF injection valve (e.g., 296) is open or closed over time. It can be understood that if the second DEF injection valve is open, DEF can be injected into the intake manifold, and when the second DEF injection valve is closed, DEF injection into the intake manifold can be prevented. Timeline 700 also includes graph 725, which indicates the engine speed (e.g., engine RPM) over time. The engine speed can be 0 (e.g., engine off) or can increase (+) compared to the engine-off state. Line 726 represents a threshold engine speed for performing a cylinder cleaning procedure, wherein the engine speed can be maintained above the threshold during the cylinder cleaning procedure. Timeline 700 also includes a graph 730 that indicates the position of the intake throttle valve (e.g., 262) over time. The throttle valve can be fully open, fully closed, or somewhere between fully open and fully closed. Timeline 700 also includes a graph 735 that indicates engine cylinder torque over time. The numbers 1, 3, 4, 2 represent each cylinder of a four-cylinder engine, and the sequence of numbers represents the firing order of the individual cylinders. Furthermore, for clarity, the numbers representing the cylinder firing order are not repeated for the entire graph 735; however, it will be understood that the firing order includes 1, 3, 4, 2 over the duration of graph 735. The torque of the individual cylinders can be monitored over time by one or more engine torque sensors (e.g., 267). Engine torque can increase (+) or decrease (-) over time. Line 736 represents the expected cylinder torque, provided there is no carbon deposit associated with a particular engine cylinder.

[0137] At time t0, the engine is operating (graphs 710 and 725) and is burning air and fuel (graph 715). The second DEF injection valve (e.g., 296) is closed. Although not explicitly shown, it can be further understood that the first DEF injection valve (e.g., 292) (if included) is also closed. The dynamic balance test (e.g.) indicates that one cylinder (cylinder 4 in this example) is performing poorly (graph 735), where poor performance can be understood as failing to produce the expected amount of cylinder torque. The expected amount of cylinder torque can include (e.g.) the expected torque level in the absence of any carbon deposits in the cylinder. However, at time t0, the conditions for performing cylinder cleaning operations have not yet been indicated.

[0138] At time t1, an indication is made that the conditions for performing the cylinder cleaning operation are met (Graph 705). For example, indicating that the conditions are met at time t1 may include an engine idling condition. Other cases for indicating whether the conditions for performing the cleaning operation are met at time t1 have been discussed in detail at step 404 of method 400, and therefore will not be repeated here for the sake of brevity. However, in this exemplary timeline 700, it can be understood that the vehicle operator has entered a cut-off condition, where the engine remains running to perform the cylinder cleaning operation. For example, a message that cylinder diagnostics are being performed may be transmitted to the vehicle operator. Such a message may be transmitted to the vehicle operator, for example, via a human-machine interface (HMI). It can be understood that the controller may be kept awake to execute the procedure.

[0139] According to Figure 4 The method 400 described herein indicates that, when conditions for performing cylinder cleaning operations are met, DEF is injected into the intake manifold via a second DEF injection valve (e.g., 296). Specifically, the second DEF injection valve can be cyclically operated such that a predetermined amount of DEF is injected into the intake manifold for a predetermined duration. When DEF is injected into the intake manifold between time t1 and time t2, the engine RPM is maintained above a threshold engine speed (indicated by line 726). However, at time t2, the engine speed drops below the threshold engine speed. Therefore, between time t2 and time t3, the throttle valve (e.g., 262) is controlled to a more open position, causing the engine speed to increase to the threshold speed at time t4.

[0140] Between time t3 and time t4, the engine speed is maintained above the threshold engine speed, and DEF is continuously injected into the intake manifold. Furthermore, between time t3 and time t4, the cylinder torque of the underperforming engine cylinder (cylinder 4 in this example) recovers to produce the expected amount of torque (represented by line 736).

[0141] In the case of restoring the underperforming engine cylinder to produce the expected torque, at time t4, the cylinder cleaning procedure is indicated to have successfully removed carbon deposits from the underperforming cylinder. Therefore, the second DEF injection valve is closed (Figure 720). However, the engine is kept running between time t4 and time t5 to allow any remaining amount of DEF injected into the intake manifold and / or within the engine cylinders to vaporize.

[0142] At time t5, the engine is deactivated (graph 710), and fuel injection to the engine cylinders is interrupted (graph 715). Therefore, the conditions for performing the cylinder cleaning diagnostic procedure are no longer indicated (graph 705). Between time t5 and time t6, the engine stops rotating. Although not explicitly stated, the controller may enter sleep mode in response to the completion of the cylinder cleaning diagnostic.

[0143] While this exemplary timeline illustrates a scenario where the conditions for performing cylinder cleaning diagnostics include a shut-off condition, in which the controller remains awake while the engine is operating to execute the procedure, the procedure can be performed under other operating conditions. For example, such a procedure can be performed under engine idling conditions, where the vehicle is stopped long enough for the procedure to be executed. For instance, the procedure can be performed in some instances if the vehicle is idling at a traffic light.

[0144] Turn now Figure 8 This illustrates an exemplary timeline 800 for performing an EGR system cleaning operation or EGR system cleaning procedure. More specifically, exemplary timeline 800 illustrates how the vehicle system can perform operations according to... Figure 5The procedure described in the method is as follows. Timeline 800 includes graph 805, which indicates over time whether conditions for performing the EGR system cleaning procedure are met. Timeline 800 also includes graph 810, which indicates engine status over time. The engine can be started and turned or rotated in the forward or default direction, or the engine can be shut down. Timeline 800 also includes graph 815, which indicates over time whether fuel injection is provided to the engine cylinders. The numbers 1, 3, 4, 2 are used to represent individual engine cylinders for graph 815, and the sequence of numbers represents the firing order of the individual cylinders. Although only two sequence of numbers are indicated for clarity, it is understood that the firing sequence repeats consistently with the indicated firing order sequence. Timeline 800 also includes graph 820, which indicates over time whether a second DEF injection valve (e.g., 296) is open or closed. It is understood that when the second DEF injection valve is open, DEF is injected into the intake manifold. Timeline 800 also includes graph 825, which indicates engine speed (e.g., engine RPM) over time. Line 826 represents a threshold engine speed, where if the engine speed drops below the threshold engine speed, the engine speed can be increased above the threshold speed. The engine speed can be 0 RPM (e.g., engine stopped), or the engine speed can increase (+) compared to when stopped. Timeline 800 also includes graph 830, which indicates the position of the intake throttle valve (e.g., 262) over time. The throttle valve can be fully open (open), fully closed (closed), or somewhere in between. Timeline 800 also includes graph 835, which indicates whether the EGR valve (e.g., 253) is open or closed over time. Timeline 800 also includes graph 840, which indicates EGR flow over time. EGR flow can be measured, for example, via one or more pressure sensors (e.g., 256). Line 841 represents the expected EGR flow rate, which includes the expected EGR flow rate in the absence of carbon deposition in the EGR channel and / or EGR valve. The EGR flow rate may include no flow (0), the expected flow rate, or a combination of the expected flow rate and no flow rate.

[0145] At time t0, the engine is operating (Graph 810) and burning air and fuel (Graph 815). The second DEF injection valve is closed (Graph 820), and the EGR valve is closed (Graph 835). Therefore, with the EGR valve closed, there is no flow in the EGR system (Graph 840). The conditions for performing the EGR cleaning procedure have not yet been met (Graph 805). However, although not explicitly stated, it is understood that the controller has identified the low flow conditions in the EGR system and has scheduled the EGR cleaning procedure to be performed in response to the fulfillment of the conditions.

[0146] Therefore, at time t1, it is indicated that the conditions for performing the EGR cleaning procedure are met. For example, in this exemplary timeline 800, it can be understood that a cut-off event has occurred. Therefore, if the conditions for performing the EGR cleaning procedure are met, the controller is kept awake at time t1, and when fuel injection to the engine cylinders stops (graph 815), the engine is kept running, for example via the motor, without fuel. Furthermore, at time t1, if the conditions for performing diagnostics are met, the EGR valve (e.g., 253) can be commanded to the open position. For example, the EGR valve can be commanded to the fully open position.

[0147] In response to the fulfillment of conditions for performing the EGR cleaning procedure, the second DEF injection valve operates in cycles between time t1 and time t2 (Figure 820) to inject a predetermined amount of DEF into the intake manifold for a predetermined duration. At time t2, after the predetermined duration has elapsed, fuel injection (and spark (if applicable)) is provided to multiple engine cylinders, but not to one engine cylinder. In other words, all engine cylinders except one can be activated to burn air and fuel (Figure 815), wherein the one engine cylinder does not burn air and fuel. In this exemplary timeline 800, cylinder 3 is depicted as deactivated or not receiving fuel injection (or spark (if applicable)).

[0148] When all but one of the engine cylinders are burning air and fuel, DEF can be continuously injected into the intake manifold between time t2 and time t3 (Figure 820). With continuous DEF injection into the intake manifold and one cylinder deactivated, the deactivated cylinder may include the route through which DEF is delivered to the EGR passage, similar to the scenario discussed above where all cylinders are deactivated but the engine is running without fuel.

[0149] When the engine burns air and fuel (except for one cylinder), the heat from combustion can cause the DEF to vaporize, which can convert the water component of the DEF into steam, thereby cleaning carbon deposits associated with the EGR valve and / or EGR passage. Therefore, the flow rate in the EGR passage is monitored between time t2 and time t3 to determine whether the EGR flow rate is still lower than expected or whether the EGR flow rate has become substantially equal to the expected EGR flow rate (e.g., within 5%).

[0150] At time t3, the EGR flow rate is indicated to include the expected flow rate. Therefore, DEF injection into the intake manifold is stopped (Graph 820). Fuel injection to the engine cylinders is maintained (Graph 815), except that all cylinders are fueled. In other words, all engine cylinders are burning air and fuel. At time t4, the EGR valve is closed, so between time t4 and time t5, the EGR flow rate is reduced to zero. Between time t4 and time t5, the engine is kept running to burn air and fuel, which promotes the removal of any carbon deposits that have been removed from the EGR passage from the exhaust manifold. At time t5, the conditions for performing EGR system cleaning diagnostics are no longer indicated (Graph 805). Therefore, at time t5, the engine is shut off (Graph 810), and fuel injection to the engine cylinders is stopped (Graph 815). Therefore, after time t5, the engine stops rotating (Graph 825). Although not explicitly shown, it is possible to put the controller into sleep mode after completing the test diagnostics.

[0151] Turn now Figure 9 This illustrates another exemplary timeline 900 for performing an EGR system cleaning operation or EGR system cleaning procedure. More specifically, exemplary timeline 900 illustrates how the vehicle system can perform operations according to... Figure 6 The procedure described in the method is shown in the timeline 900. The timeline 900 includes a graph 905 indicating whether the conditions for performing the procedure according to the timeline are met. Figure 6The conditions of the EGR cleaning procedure of method 600 are depicted below. Timeline 900 also includes graph 910, which indicates engine status over time. The engine may be off or may be rotating in the forward (fwd) or reverse (rev) direction. Timeline 900 also includes graph 915, which indicates whether fuel injection to the engine cylinders is on or off over time. Timeline 900 also includes graph 920, which indicates whether a first DEF injection valve (e.g., 292) is on or off over time. It is understood that when the first DEF injection valve is "on", DEF is injected into the exhaust manifold. Timeline 900 also includes graph 925, which indicates engine speed (e.g., engine RPM) over time. Line 926 represents a threshold engine speed, which can be controlled to return the engine to a desired engine speed if the engine speed drops below the threshold speed during a specific portion of the test (e.g., while the engine is started to burn air and fuel). Timeline 900 also includes graph 930, which indicates the position of the intake throttle valve (e.g., 262) over time. The throttle valve may be fully closed (closed), fully open (open), or somewhere in between. Timeline 900 also includes graph 935, which indicates the state of the EGR valve (e.g., 253) over time. The EGR valve may be open or closed over time. Timeline 900 also includes graph 940, which indicates the EGR flow rate in the EGR system over time. The EGR flow rate may be the expected EGR flow rate under specific vehicle operating conditions, may be zero flow (0), or may be somewhere in between. Line 941 represents the expected EGR flow rate under specific operating conditions.

[0152] At time t0, the engine is off (Graph 910). Although not explicitly shown, it can be understood that the engine has been off for a certain duration, causing the oxidation catalyst (e.g., 226) temperature to be below a threshold temperature. This threshold temperature may include the temperature at which DEF can be transported across the catalyst without vaporizing the DEF. At time t0, the conditions for performing EGR cleaning diagnostics are not yet indicated (Graph 905). With the engine off, fuel injection to the engine cylinders is also shut off (Graph 915). Furthermore, because the conditions for performing the EGR cleaning procedure are not indicated, the first DEF injection valve is closed (Graph 920). With the engine off, the engine RPM is 0 (Graph 925), and the throttle position includes the off throttle position (Graph 930). Additionally, the EGR valve is closed (Graph 935), and there is no EGR flow at time t0 (Graph 940).

[0153] At time t1, the conditions for performing the EGR cleaning procedure are met (Graph 905). For example, it can be understood that at time t1, a key-on event has occurred, whereby the EGR cleaning procedure is scheduled for the next available opportunity where the conditions for performing the procedure are met. In other words, it can be understood that at time t1, the oxidation catalyst is below the threshold temperature.

[0154] If the conditions for performing the EGR cleaning procedure are met at time t1, the EGR valve (e.g., 253) is commanded to open at time t1. With the EGR valve commanded to open, the engine is rotated in reverse orientation between time t1 and time t2 by (e.g., a motor, e.g., 120). Furthermore, the first DEF injection valve is operated in a working cycle between time t1 and time t2 to inject DEF into the exhaust manifold. This working cycle may include a cycle for injecting a predetermined amount of DEF into the exhaust manifold for a predetermined duration. The engine speed is controlled to a predetermined or desired engine speed between time t1 and time t2 (Figure 925). By rotating the engine in reverse orientation without fuel while injecting DEF into the exhaust manifold, it is understood that DEF can be delivered to the EGR passage via the engine due to the open EGR valve. This delivery of DEF to the EGR passage can be performed for a predetermined duration.

[0155] At time t2, the predetermined duration has elapsed. Therefore, the first DEF injection valve closes, and the engine stops rotating in the reverse direction. In other words, the motor can be deactivated between time t2 and time t3, and the engine can stop rotating (Figure 925). After the engine stops rotating, it can be restarted at time t3 in a mode where the engine burns air and fuel. Specifically, the engine can be started to rotate in the forward direction (Figure 910), where fuel (Figure 915) (and spark (where applicable)) is supplied to each of the engine cylinders (1, 3, 4, 2). By operating the engine to burn air and fuel, it is understood that heat from combustion can be directed to the EGR passage (because the EGR valve is kept open) to vaporize the DEF transported to the EGR passage. Therefore, between time t3 and time t4, the engine is controlled to a speed above a threshold speed (represented by line 926). The threshold speed may include a speed at which engine stall can be avoided or prevented during the procedure. In addition, between time t3 and time t4, the EGR flow rate is monitored, for example, via a pressure sensor (e.g., 256).

[0156] At time t4, the flow rate in the EGR system reaches the expected EGR flow rate, which includes the expected flow rate under given operating conditions, assuming no carbon deposition associated with the EGR valve and / or EGR channel.

[0157] When the EGR flow returns to the expected flow at time t4, the EGR valve closes (Figure 935), and therefore, between time t4 and time t5, the EGR flow in the EGR passage drops to zero. However, the engine is kept running between time t4 and time t5 to burn air and fuel. The engine is kept running so that any carbon deposits that were removed from the EGR passage and / or EGR valve when the EGR valve closed can be forced out of the exhaust manifold. The engine can be kept running for a predetermined duration after the indication that the EGR passage and / or EGR valve has been cleaned. Therefore, at time t5, the predetermined duration expires, and therefore, the conditions for performing the EGR cleaning procedure are no longer indicated (Figure 905). Furthermore, in this exemplary timeline, it can be understood that the key-on event at the start time t1 is intended to drive the vehicle to another destination. Therefore, although fuel injection stops at time t5, it can be understood that the engine is kept rotating in the forward direction via the motor, thereby enabling the vehicle to start in electric operation mode. Therefore, between time t5 and time t6, the engine is kept rotating in the positive direction without fuel.

[0158] In this way, the vehicle's EGR system can be cleaned both on-board and on demand. By equipping vehicles with the ability to clean the EGR system in response to indications of potential carbon buildup, engine degradation can be prevented. Furthermore, fuel economy can be improved, and customer satisfaction can be increased by reducing the time and costs associated with vehicle maintenance.

[0159] One technological advantage is the recognition that the DEF injection system can be replaced with a clean EGR system. Another advantage is the recognition that in hybrid vehicles with a motor capable of rotating or turning the engine without fuel, the engine can be rotated in the opposite direction without fuel while the EGR valve is open, injecting DEF into the exhaust manifold simultaneously. This delivers the DEF into the EGR passage. After the DEF is delivered into the EGR passage, the engine can be started in combustion mode, directing heat from the combustion engine into the EGR passage, where moisture in the DEF can be vaporized, effectively cleaning carbon deposits associated with the EGR valve and / or EGR passage. Another advantage is the recognition that such a procedure can be performed under conditions where the oxidation catalyst located upstream of the DEF injection point in the exhaust manifold is below a threshold temperature, preventing the DEF from vaporizing before reaching the EGR passage.

[0160] This article references Figures 1 to 3B The system described and the references in this article Figures 4 to 6The described methods can implement one or more systems and methods. In one example, a method includes reducing carbon deposits in the exhaust gas recirculation (EGR) system of a vehicle's engine, the EGR system being configured to deliver at least a portion of exhaust gas in the exhaust manifold to the engine's intake manifold by injecting diesel exhaust fluid into the engine's exhaust manifold and delivering the diesel exhaust fluid to the EGR system. In a first example of the method, the method further includes, wherein delivering the diesel exhaust fluid to the EGR system further includes commanding the opening of an EGR valve. A second example of the method optionally includes the first example and further includes reducing carbon deposits in response to a lower-than-expected flow rate in the EGR system when the EGR valve is open, and / or in response to a higher-than-expected flow rate in the EGR system when the EGR valve is closed. A third example of the method optionally includes any one or more of, or each of, the first and second examples, and further includes wherein delivering the diesel exhaust fluid to the exhaust gas recirculation system further includes: simultaneously injecting the diesel exhaust fluid into the exhaust manifold for a predetermined duration, rotating the engine in a reverse direction without fuel. A fourth example of the method optionally includes any one or more of, or each of, the first to the third examples, and further includes, after delivering the diesel exhaust fluid to the exhaust gas recirculation system, operating the engine to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system. A fifth example of the method optionally includes any one or more of, or each of, the first to the fourth examples, and further includes wherein operating the engine to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system includes operating the engine to burn air and fuel. A sixth embodiment of the method optionally includes any one or more of the first to the fifth embodiments, and further includes the diesel exhaust fluid comprising water and urea components, and wherein vaporizing the diesel exhaust fluid converts the water component into steam, which reduces the carbon deposits in the exhaust gas recirculation system. A seventh embodiment of the method optionally includes any one or more of the first to the sixth embodiments, and further includes controlling an exhaust tuning valve to direct exhaust heat to the exhaust gas recirculation system while operating the engine to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system. An eighth embodiment of the method optionally includes any one or more of the first to the seventh embodiments, and further includes stopping the injection of the diesel exhaust fluid into the exhaust manifold while operating the engine to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system.A ninth embodiment of the method optionally includes any one or more or each of the first to eighth embodiments, and further includes injecting the diesel exhaust treatment fluid into the intake manifold when the oxidation catalyst located in the exhaust passage of the engine is below a threshold temperature.

[0161] Another example of a method includes: in a first operating condition of a vehicle, injecting diesel exhaust fluid into the exhaust manifold of the vehicle's engine to fill a selective catalytic reduction catalyst positioned in the exhaust manifold with ammonia; and in a second operating condition of the vehicle, injecting the diesel exhaust fluid into the exhaust manifold of the vehicle's engine to reduce carbon deposits in the exhaust gas recirculation system. In the first example of the method, the method further includes the first operating condition comprising an oxidation catalyst positioned upstream of an injection point for injecting the diesel exhaust fluid into the exhaust manifold at a temperature higher than or lower than a threshold temperature, and the second operating condition comprising the oxidation catalyst at a temperature lower than the threshold temperature. A second example of the method optionally includes the first example, and further includes the first operating condition comprising the engine burning air and fuel during the injection; and the second operating condition comprising the engine not burning air and fuel during the injection. A third example of the method optionally includes any one or more of the first to second examples, and further includes the second operating condition further including rotating the engine in the reverse direction without fuel for a predetermined duration during the injection to deliver the diesel exhaust fluid to the exhaust gas recirculation system; and stopping rotating the engine in the reverse direction in response to the elapse of the predetermined duration, and starting the engine to combust air and fuel. A fourth example of the method optionally includes any one or more of the first to third examples, and further includes one or more of the following: increasing the speed of the engine rotating in the reverse direction without fuel and / or the amount of diesel exhaust fluid injected into the exhaust manifold as the level of condensate stored in the exhaust gas recirculation cooler located in the exhaust gas recirculation system decreases; and one or more of the following of the following: decreasing the speed of the engine rotating in the reverse direction without fuel and / or the amount of diesel exhaust fluid injected into the exhaust manifold as the level of condensate stored in the exhaust gas recirculation cooler increases. A fifth example of the method optionally includes any one or more of, or each of, the first to the fourth examples, and further includes the first operating condition being independent of the state of the exhaust gas recirculation valve; and the second operating condition including commanding the exhaust gas recirculation valve to open just before injecting the diesel exhaust fluid into the exhaust manifold. A sixth example of the method optionally includes any one or more of, or each of, the first to the fifth examples, and further includes indicating carbon deposits in the exhaust gas recirculation system in the second operating condition in response to an indication that the flow rate in the exhaust gas recirculation system is greater than a threshold difference relative to a expected or desired flow rate under predetermined engine operating conditions.

[0162] A system for a hybrid vehicle includes: an engine system comprising an engine having a plurality of engine cylinders and at least an exhaust manifold; a diesel exhaust fluid (DEF) injection system comprising a first DEF delivery line selectively fluidly connected to the exhaust manifold via a first DEF injection valve at a location in the exhaust manifold between an oxidation catalyst and a selective catalytic reduction catalyst; an exhaust gas recirculation system comprising an exhaust gas recirculation valve and a pressure sensor both located in an exhaust gas recirculation passage, and an exhaust gas recirculation cooler; a motor configured to rotate the engine without fuel; and a controller storing instructions in a non-transitory memory. When executed, the instructions cause the controller to: in a first operating condition including a key-on event and an indication of carbon deposits in the exhaust gas recirculation system, command to open the exhaust gas recirculation valve; circulate the first DEF injection valve according to the condensate level in the exhaust gas recirculation cooler and rotate the engine in reverse without fuel via the motor to deliver diesel exhaust fluid stored in a canister in the DEF injection system to the exhaust gas recirculation system; and after a predetermined duration, stop circulating the first DEF injection valve, stop rotating the engine without fuel, and start the engine to burn air and fuel to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system. In a first instance of the system, the system further includes wherein the controller stores additional instructions to circulate the first DEF injection valve and operate the engine to burn air and fuel in a second operating condition to fill the selective catalytic reduction catalyst with ammonia. A second instance of the system optionally includes the first instance and further includes wherein the first operating condition includes a temperature of the oxidation catalyst below a threshold temperature, and wherein the second operating condition is independent of the temperature of the oxidation catalyst.

[0163] It should be noted that the exemplary control and estimation routines included herein can be used in various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by a control system comprising a combination of controllers and various sensors, actuators, and other engine hardware. The specific routines described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, etc. Therefore, the various actions, operations, and / or functions described may be performed in the illustrated sequence, in parallel, or in some cases omitted. Similarly, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for the sake of simplicity of illustration and description. One or more of the illustrated actions, operations, and / or functions can be repeatedly performed according to the specific strategy used. Furthermore, the described actions, operations, and / or functions can clearly represent code to be programmed into a non-transitory memory of a computer-readable storage medium in the engine control system, wherein the described actions are implemented by executing instructions in a system comprising a combination of various engine hardware components and electronic controllers.

[0164] It will be understood that the configurations and routines disclosed herein are exemplary in nature and should not be viewed in a limiting sense, as numerous variations are possible. For example, the above techniques can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein with other features, functions, and / or properties.

[0165] The appended claims specifically point to particular combinations and sub-combinations considered novel and non-obvious. These claims may refer to an element or a first element or its equivalent. Such claims should be understood to include one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amending these claims or by presenting new claims in this or related applications. Such claims, whether broader, narrower, equivalent, or different in scope from the original claims, are also considered to be included within the subject matter of this disclosure.

[0166] According to the present invention, a method for reducing carbon deposits in the exhaust gas recirculation system of a vehicle engine is provided, the exhaust gas recirculation system being configured to deliver at least a portion of the exhaust gas in the exhaust manifold to the engine intake manifold by injecting diesel exhaust fluid into the exhaust manifold of the engine and delivering the diesel exhaust fluid to the exhaust gas recirculation system.

[0167] According to the implementation scheme, the present invention is further characterized in that transporting the diesel exhaust treatment fluid to the exhaust recirculation system also includes commanding the exhaust recirculation valve to open.

[0168] According to an embodiment, the invention is further characterized by reducing carbon deposits in response to a lower-than-expected flow rate in the exhaust gas recirculation system when the exhaust gas recirculation valve is open, and / or in response to a higher-than-expected flow rate in the exhaust gas recirculation system when the exhaust gas recirculation valve is closed.

[0169] According to the implementation scheme, the present invention is further characterized in that transporting the diesel exhaust fluid to the exhaust recirculation system also includes: simultaneously injecting the diesel exhaust fluid into the exhaust manifold for a predetermined duration and rotating the engine in the opposite direction without fuel.

[0170] According to the implementation scheme, the invention is further characterized in that, after the diesel exhaust fluid is delivered to the exhaust gas recirculation system, the engine is operated to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system.

[0171] According to the embodiments, the invention is further characterized in that operating the engine to vaporize the diesel exhaust treatment fluid transported to the exhaust gas recirculation system includes operating the engine to burn air and fuel.

[0172] According to the implementation scheme, the diesel exhaust treatment fluid includes a water component and a urea component, and wherein vaporizing the diesel exhaust treatment fluid converts the water component into steam, which reduces the carbon deposits in the exhaust recirculation system.

[0173] According to the embodiments, the invention is further characterized by controlling the exhaust tuning valve to direct the exhaust heat to the exhaust recirculation system while operating the engine to vaporize the diesel exhaust treatment fluid transported to the exhaust recirculation system.

[0174] According to an embodiment, the invention is further characterized in that the injection of the diesel exhaust fluid into the exhaust manifold is stopped while the engine is operated to vaporize the diesel exhaust fluid transported to the exhaust recirculation system.

[0175] According to the embodiments, the invention is further characterized in that the diesel exhaust treatment fluid is injected into the intake manifold when the oxidation catalyst located in the exhaust passage of the engine is below a threshold temperature.

[0176] According to the present invention, a method is provided, the method comprising: in a first operating condition of a vehicle, injecting a diesel exhaust fluid into the exhaust manifold of the vehicle's engine to fill a selective catalytic reduction catalyst positioned in the exhaust manifold with ammonia; and in a second operating condition of the vehicle, injecting the diesel exhaust fluid into the exhaust manifold of the vehicle's engine to reduce carbon deposits in the exhaust gas recirculation system.

[0177] According to the implementation scheme, the first operating condition includes an oxidation catalyst positioned upstream of an injection point for injecting the diesel exhaust fluid into the exhaust manifold, with a temperature higher than or lower than a threshold temperature; and wherein the second operating condition includes the oxidation catalyst having a temperature lower than the threshold temperature.

[0178] According to the implementation scheme, the first operating condition includes the engine burning air and fuel during the injection; and the second operating condition includes the engine not burning air and fuel during the injection.

[0179] According to the implementation scheme, the second operating condition further includes rotating the engine in the reverse direction for a predetermined duration without fuel during the injection to deliver the diesel exhaust fluid to the exhaust gas recirculation system; and stopping the engine from rotating in the reverse direction in response to the elapse of the predetermined duration, and starting the engine to burn air and fuel.

[0180] According to the implementation scheme, one or more of the following occurs: as the level of condensate stored in the exhaust recirculation cooler located in the exhaust recirculation system decreases, the speed of the engine rotating in the reverse direction without fuel and / or the amount of diesel exhaust fluid injected into the exhaust manifold increases; and as the level of condensate stored in the exhaust recirculation cooler increases, one or more of the following occurs: as the level of condensate stored in the exhaust recirculation cooler increases, the speed of the engine rotating in the reverse direction without fuel and / or the amount of diesel exhaust fluid injected into the exhaust manifold decreases.

[0181] According to the implementation scheme, the first operating condition is independent of the state of the exhaust gas recirculation valve; and the second operating condition includes commanding the exhaust gas recirculation valve to open just before the diesel exhaust fluid is injected into the exhaust passage.

[0182] According to the implementation scheme, carbon deposits in the exhaust gas recirculation system under the second operating condition are indicated in response to an indication that the flow rate in the exhaust gas recirculation system under predetermined engine operating conditions is greater than a threshold difference relative to the expected or desired flow rate.

[0183] According to the present invention, a system for a hybrid vehicle is provided, the system comprising: an engine system including an engine having a plurality of engine cylinders and at least an exhaust manifold; a diesel exhaust fluid (DEF) injection system including a first DEF delivery line selectively fluidly connected to the exhaust manifold via a first DEF injection valve at a location in the exhaust manifold between an oxidation catalyst and a selective catalytic reduction catalyst; an exhaust gas recirculation system including an exhaust gas recirculation valve and a pressure sensor both located in an exhaust gas recirculation passage, and an exhaust gas recirculation cooler; a motor configured to rotate the engine without fuel; and a controller storing instructions in a non-transitory storage. In the storage tank, when the instruction is executed, the controller causes the controller to: under a first operating condition including a key-on event and an indication of carbon deposits in the exhaust gas recirculation system, command to open the exhaust gas recirculation valve; to operate the first DEF injection valve according to the condensate level in the exhaust gas recirculation cooler and to rotate the engine in reverse without fuel via the motor to deliver diesel exhaust fluid stored in the tank of the DEF injection system to the exhaust gas recirculation system; and after a predetermined duration, to stop operating the first DEF injection valve and to stop rotating the engine without fuel, and to start the engine to burn air and fuel to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system.

[0184] According to the implementation scheme, the controller stores other instructions to cause the first DEF injection valve to operate in a second operating condition and to operate the engine to burn air and fuel to fill the selective catalytic reduction catalyst with ammonia.

[0185] According to the implementation scheme, the first operating condition includes the temperature of the oxidation catalyst being below a threshold temperature, and wherein the second operating condition is independent of the temperature of the oxidation catalyst.

Claims

1. A method for a vehicle, the method comprising: Carbon deposits in the exhaust gas recirculation system of a vehicle's engine are reduced by rotating the engine in reverse during a period when fuel injection is deactivated for each cylinder of the engine and injecting diesel exhaust fluid into the engine's exhaust manifold to deliver the diesel exhaust fluid to the exhaust gas recirculation system, and then restarting combustion in the cylinders from engine shutdown.

2. The method of claim 1, wherein delivering the diesel exhaust fluid to the exhaust recirculation system further comprises commanding the exhaust recirculation valve to open.

3. The method of claim 2, further comprising reducing the carbon deposits in response to a lower-than-expected flow rate in the exhaust gas recirculation system when the exhaust gas recirculation valve is open, and / or in response to a higher-than-expected flow rate in the exhaust gas recirculation system when the exhaust gas recirculation valve is closed.

4. The method of claim 1, wherein delivering the diesel exhaust fluid to the exhaust gas recirculation system further comprises: During a predetermined duration, the diesel exhaust fluid is injected into the exhaust manifold while the engine rotates in the opposite direction without fuel.

5. The method of claim 1, wherein after the diesel exhaust fluid is delivered to the exhaust gas recirculation system, the engine is operated to vaporize the diesel exhaust fluid delivered to the exhaust gas recirculation system.

6. The method of claim 5, wherein operating the engine to vaporize the diesel exhaust treatment fluid delivered to the exhaust gas recirculation system comprises operating the engine to burn air and fuel.

7. The method of claim 5, wherein the diesel exhaust fluid comprises a water component and a urea component, and wherein vaporizing the diesel exhaust fluid converts the water component into steam, the steam reducing the carbon deposits in the exhaust recirculation system.

8. The method of claim 5, further comprising controlling an exhaust tuning valve to direct exhaust heat to the exhaust recirculation system while operating the engine to vaporize the diesel exhaust treatment fluid delivered to the exhaust recirculation system.

9. The method of claim 5, further comprising stopping the injection of the diesel exhaust fluid into the exhaust manifold while operating the engine to vaporize the diesel exhaust fluid delivered to the exhaust recirculation system.

10. The method of claim 1, further comprising injecting the diesel exhaust fluid into the intake manifold when the oxidation catalyst located in the exhaust passage of the engine is below a threshold temperature.

11. A system for a hybrid vehicle, the system comprising: An engine system, the engine system comprising an engine having multiple engine cylinders and at least an exhaust manifold; A diesel exhaust fluid (DEF) injection system, the diesel exhaust fluid injection system comprising a first DEF delivery line selectively and fluidly connected to the exhaust manifold via a first DEF injection valve at a location in the exhaust manifold between an oxidation catalyst and a selective catalytic reduction catalyst; An exhaust gas recirculation system, the exhaust gas recirculation system including an exhaust gas recirculation valve and a pressure sensor, both located in an exhaust gas recirculation passage, and an exhaust gas recirculation cooler; A motor configured to rotate the engine without fuel; and a controller that stores instructions in non-transitory memory, the instructions causing the controller to: In a first operating condition that includes an indication of a key-on event and carbon buildup in the exhaust gas recirculation system, the exhaust gas recirculation valve is commanded to open. The first DEF injection valve is operated cyclically according to the level of condensate in the exhaust gas recirculation cooler, and the engine is rotated in reverse without fuel via the motor to deliver diesel exhaust fluid stored in the tank of the diesel exhaust fluid injection system to the exhaust gas recirculation system. as well as After a predetermined duration, the first DEF injection valve is stopped from operating in a cycle, and the engine is stopped from rotating in reverse without fuel. The engine is then started to burn air and fuel to vaporize the diesel exhaust treatment fluid delivered to the exhaust recirculation system.

12. The system of claim 11, wherein the diesel exhaust fluid comprises a mixture of urea and water, and wherein the controller stores additional instructions to cause the first DEF injection valve to operate in a second operating condition and to operate the engine to burn air and fuel to fill the selective catalytic reduction catalyst with ammonia.

13. The system of claim 12, wherein the first operating condition includes a temperature of the oxidation catalyst below a threshold temperature, and wherein the second operating condition is independent of the temperature of the oxidation catalyst.

14. The system of claim 11, further comprising an exhaust tuning valve, wherein the controller stores additional instructions to control the exhaust tuning valve in the first operating condition to direct heat from exhaust gases emitted during engine startup for combustion of air and fuel to the exhaust gas recirculation system.

15. The system of claim 11, further comprising a pressure sensor located in the exhaust gas recirculation system, and wherein the controller stores additional instructions to monitor the flow rate in the exhaust gas recirculation system while starting the engine to combust air and fuel; and In response to the condition that the engine is burning air and fuel and that the exhaust recirculation valve is open, the flow rate in the exhaust recirculation system includes the expected or desired flow rate, indicating that the carbon deposits have been reduced or removed.

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