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

Abstract

Methods and systems for mitigating problems associated with engine performance lag are provided. In one example, a method includes, in response to an indication of degradation of one or more cylinders in the engine, reducing carbon buildup associated with the one or more cylinders by injecting diesel exhaust fluid into an intake manifold of the engine as the engine combusts air and fuel. In this manner, a water content of the diesel exhaust fluid can vaporize in the one or more engine cylinders, which can effectively reduce the carbon buildup.

Description

TECHNICAL FIELD

[0001] The present specification generally relates to controlling a vehicle engine system. With methods and systems for cleaning certain engine components via on-board and on-demand techniques.

[0002] BACKGROUND / SUMMARY

[0003] As an engine accumulates mileage, carbon deposits can accumulate over time. Such carbon deposits can accumulate on the top of one or more pistons in one or more engine cylinders, and / or on the intake and exhaust valves of the engine cylinders. Such carbon accumulation can be the result of frequent short driving cycles, frequent use of low-grade fuel, improper air-fuel ratio during vehicle operation, and the like. With such carbon accumulation, the engine can run rough and can be sluggish in response (laggy). Moreover, such carbon accumulation can reduce fuel economy, increase exhaust emissions, and can cause knock issues when the engine burns air and fuel.

[0004] To address these issues, engine additives are typically utilized that can be used to clean such carbon deposits from the engine cylinders. However, such additives can be introduced into the intake manifold of the engine, which can thus require invasive action, such as breaking a vacuum line in the engine, and introducing the additive fluid into the engine via the vacuum line. In other words, such a solution can be undesirable to a vehicle operator, as the vehicle can need to be serviced to perform such an operation. Still further, such additives are expensive, and many vehicle operators can not know that such additives even exist or that they can be useful for certain aspects of vehicle operation. Still further, there can be a future situation where vehicles are autonomously driven (e.g., autonomous vehicles), and thus, there can not be a presence of a driver to notice engine lag due to carbon accumulation. In such a situation, fuel economy can be reduced, which can result in undesirable emissions being released into the atmosphere.

[0005] The present inventors have recognized these issues, and have developed systems and methods that address these issues, at least in part. In one example, a method includes, in response to an indication of degradation in one or more cylinders of a vehicle engine, reducing carbon accumulation associated with the one or more cylinders by injecting a diesel exhaust fluid into an intake manifold of the engine and drawing the diesel exhaust fluid into the engine as the engine burns air and fuel. In this way, carbon accumulation can be reduced in an on-board and on-demand manner.

[0006] In one example of the method, the diesel exhaust fluid is stored in a tank located in a diesel exhaust fluid system, wherein a first diesel exhaust fluid line is configured to selectively direct the diesel exhaust fluid to an exhaust passage, and wherein a second diesel exhaust fluid line is configured to selectively direct the diesel exhaust fluid to the intake manifold.

[0007] The above advantages and other advantages and features of the present description will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.

[0008] It should be understood that the above overview is provided as a simplified form to introduce some concepts that are further described in the detailed description. It does not mean to identify key or essential features of the claimed subject matter, the scope of which is defined solely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any or all of the disadvantages mentioned above or any disadvantages mentioned in any section of this disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0009] Figure 1 An example vehicle propulsion system is schematically illustrated.

[0010] Figure 2A An example vehicle system having a diesel exhaust fluid (DEF) system configured to inject a reductant into an exhaust system of an engine is schematically illustrated.

[0011] Figure 2B An example vehicle system having a DEF system configured to inject a reductant into an exhaust system and / or an intake system of an engine is schematically illustrated.

[0012] Figures 3A-3B An example H-bridge circuit that can be used to rotate a vehicle engine in a forward or reverse direction is schematically illustrated.

[0013] Figure 4 A high level flowchart for performing a cleaning operation of an engine cylinder is shown.

[0014] Figure 5 A high level flowchart for performing an exhaust gas recirculation system cleaning operation is shown.

[0015] Figure 6 A high level flowchart for performing another example of an exhaust gas recirculation system cleaning operation is shown.

[0016] Figure 7 An example timeline for performing a cleaning operation of an engine cylinder according to the method of Figure 4

[0017] Figure 8 ​An exemplary timeline for performing an exhaust gas recirculation system cleaning operation is depicted in accordance with the method of Figure 5

[0018] Figure 9 An exemplary timeline for performing an exhaust gas recirculation system cleaning operation is depicted in accordance with the method of Figure 6 DETAILED DESCRIPTION

[0019] The following description relates to systems and methods for performing on-board and on-demand cleaning operations to reduce or eliminate carbon build-up associated with various engine component parts. The systems and methods can include evaporating diesel exhaust fluid (DEF) from a DEF injection system, which can result in the water content of the DEF being converted to steam, which can effectively clean carbon build-up. Such systems and methods are particularly useful in hybrid vehicles, such as Figure 1 the hybrid vehicle depicted in FIG. 1, where a motor can be utilized to rotate an un-fueled engine, which can include ways to deliver DEF to an exhaust gas recirculation (EGR) system, such as the system depicted in FIG. 2. In one example, DEF can be injected into an exhaust passage (see FIG. 3) and directed to the EGR system by having the engine un-fueled in a reverse direction with the EGR valve open. In another example, DEF can be injected into an intake manifold via an introduced DEF line, as shown in FIG. 4, where the engine can be un-fueled in a forward direction to direct the DEF to the EGR system with the EGR valve open. In either case, after the DEF is directed to the EGR system, the engine can be operated in a combustion mode to direct heat to the EGR system for evaporating the water content of the DEF, which can effectively clean carbon deposits associated with the EGR valve or EGR passage. In another example, DEF can be injected into an intake manifold while the engine is combusting air and fuel, such that the DEF can be drawn into the engine, which can clean carbon deposits from the engine cylinders as the DEF evaporates within the engine cylinders. Figure 2A Figure 2A Figure 2B

[0020] To have the engine un-fueled in a forward or reverse direction, a H-bridge, such as the one depicted in FIG. 5, can be utilized. Figures 3A-3B A method is depicted by which carbon deposits can be removed from an engine cylinder via DEF injection into an intake manifold, Figure 4 A method is depicted by which carbon deposits can be removed from an EGR system via DEF injection into an intake manifold, and Figure 5 A method is depicted by which carbon deposits can be removed from an EGR system via DEF injection into an exhaust manifold. Figure 6 A method is depicted by which carbon deposits can be removed from an EGR system via DEF injection into an exhaust manifold. Figure 7 A method is depicted by which carbon deposits can be removed from an EGR system via DEF injection into an exhaust manifold.​​​​​Figure 4 Timeline of engine cylinder cleaning operations. Figure 8 Describing the use of Figure 5 The timeline of EGR system cleaning operations, and Figure 9 Describing the use of Figure 6 Timeline of EGR system cleaning operations.

[0021] Figure 1 An exemplary vehicle propulsion system 100 is illustrated. 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 an energy source different from that of the engine 110. For example, the engine 110 may consume liquid fuel (e.g., gasoline) to produce engine output, while the motor 120 may consume electrical energy to produce motor output. Therefore, a vehicle having the propulsion system 100 may be referred to as a hybrid electric vehicle (HEV).

[0022] 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 a deactivated state), where fuel combustion at the engine is stopped. For example, in a selected operating condition, when the engine 110 is deactivated, the motor 120 can propel the vehicle via the drive wheels 130 as indicated by arrow 122.

[0023] During other operating conditions, engine 110 can be deactivated (as described above), while motor 120 can be operated to charge energy storage device 150. For example, as indicated by arrow 122, motor 120 can receive wheel torque from drive wheels 130, whereby the motor can convert the vehicle's kinetic energy into electrical energy to be stored in energy storage device 150, as indicated by arrow 124. This operation can be referred to as regenerative braking of the vehicle. Thus, 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 to be stored in energy storage device 150, as indicated by arrow 162.

[0024] Still during other operating conditions, as indicated by arrow 142, the engine 110 can be operated by combusting fuel received from the fuel system 140. For example, when the motor 120 is deactivated, the engine 110 can operate to propel the vehicle via the drive wheels 130, as indicated by arrow 112. During other operating conditions, both the engine 110 and the motor 120 can each be operated to propel the vehicle via the drive wheels 130, as indicated by arrows 112 and 122, respectively. Configurations in which both the engine and the motor can selectively propel the vehicle can be referred to as parallel-type vehicle propulsion systems. It should be noted that, in some examples, the motor 120 can propel the vehicle via a first set of drive wheels, and the engine 110 can propel the vehicle via a second set of drive wheels.

[0025] In other examples, the vehicle propulsion system 100 can be configured as a series-type vehicle propulsion system, whereby the engine does not directly propel the drive wheels. Rather, the engine 110 can be operated to power the motor 120, which can in turn 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 in turn supply electrical energy to one or more 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 in turn provide a generator function to convert engine output into electrical energy, which can be stored at the energy storage device 150 for subsequent use by the motor.

[0026] In other examples, to be discussed in further detail below, the motor 120 can be configured to use energy provided via the energy storage device 150 to rotate the engine without fuel in a forward direction (e.g., a default orientation) or a reverse orientation, as exemplified by arrow 186.

[0027] The fuel system 140 can include one or more fuel storage tanks 144 for storing fuel on the vehicle. For example, the fuel tank 144 can store one or more liquid fuels, including but not limited to: gasoline, diesel, and alcohol fuels. In some examples, fuel can be stored on the vehicle as a blend of two or more different fuels. For example, the fuel tank 144 can be configured to store a blend of gasoline and ethanol (e.g., E10, E85, etc.) or a blend of gasoline and methanol (e.g., M10, M85, etc.), whereby these fuels or fuel blends can be delivered to the engine 110, as indicated by arrow 142. Other suitable fuels or fuel blends can also be supplied to the engine 110, which can be combusted at the engine to produce engine output. The engine output can be used to propel the vehicle, as indicated by arrow 112, or to recharge the energy storage device 150 via the motor 120 or the generator 160.

[0028] In some examples, the energy storage device 150 can be configured to store electrical energy that can be supplied to other electrical loads residing on the vehicle (in addition to the motor), including cabin heating and air conditioning, engine starting, headlamps, cabin audio and video systems, etc. As non-limiting examples, the energy storage device 150 can include one or more batteries and / or capacitors.

[0029] The control system 190 can be in communication with one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160. The control system 190 can receive sensory feedback information from one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160. In addition, the control system 190 can send control signals to one or more of the engine 110, the motor 120, the fuel system 140, the energy storage device 150, and the generator 160 in response to the sensory feedback. The control system 190 can receive an indication of an operator-requested vehicle propulsion system output from the vehicle operator 102. For example, the control system 190 can receive sensory feedback from a pedal position sensor 194 in communication with a pedal 192. The pedal 192 can illustratively be a brake pedal and / or an accelerator pedal. In addition, in some examples, the control system 190 can be in communication with a remote engine start receiver 195 (or transceiver) that receives a wireless signal 106 from the key fob 104 having a remote start button 105. In other examples (not shown), the remote engine start can be initiated via a cellular phone or smart phone-based system, where the user's cellular phone sends data to a server and the server communicates with the vehicle to start the engine.

[0030] As indicated by arrow 184, the energy storage device 150 can periodically receive electrical energy from a power source 180 (e.g., not part of the vehicle) residing outside of the vehicle. As a non-limiting example, the vehicle propulsion system 100 can be configured as a plug-in hybrid electric vehicle (HEV), whereby electrical energy can be supplied from the power source 180 to the energy storage device 150 via an electrical energy transfer cable 182. The electrical transfer cable 182 can electrically couple the energy storage device 150 and the power source 180 during a recharging operation of the energy storage device 150 from the power source 180. The electrical transfer cable 182 can be disconnected between the power source 180 and the energy storage device 150 when the vehicle propulsion system is operated to propel the vehicle. The control system 190 can identify and / or control the amount of electrical energy stored at the energy storage device, which can be referred to as the state of charge (SOC).

[0031] In other examples, the electrical transfer cable 182 can be omitted, where electrical energy can be received wirelessly at the energy storage device 150 from the power source 180. For example, the energy storage device 150 can receive electrical energy from the power source 180 via one or more of electromagnetic induction, radio waves, and electromagnetic resonance. Thus, it should be understood that any suitable method can be used to recharge the energy storage device 150 from a power source that is not part of the vehicle. In this manner, the motor 120 can propel the vehicle by utilizing a source of energy other than fuel used by the engine 110.

[0032] The fuel system 140 can periodically receive fuel from a fuel source that resides outside of the vehicle. As a non-limiting example, as indicated by arrow 172, the vehicle propulsion system 100 can be refueled by receiving fuel via a fuel dispensing device 170. In some examples, the fuel tank 144 can be configured to store fuel received from the fuel dispensing device 170 until the fuel is supplied to the engine 110 for combustion. In some examples, the control system 190 can receive an indication of a fuel level stored at the fuel tank 144 via a fuel level sensor. The fuel level stored at the fuel tank 144 (e.g., as identified by the fuel level sensor) can be communicated to the vehicle operator, for example, via a fuel gauge or indication in the vehicle dashboard 196.

[0033] The vehicle propulsion system 100 can also include an ambient temperature / humidity sensor 198 and roll stability control sensors, such as lateral and / or longitudinal and / or yaw rate sensors 199. The vehicle dashboard 196 can include indicator lights and / or text-based displays, where messages are displayed to the operator. The vehicle dashboard 196 can also include various input portions for receiving operator input, such as buttons, touchscreens, voice input / recognition, etc. For example, the vehicle dashboard 196 can include a refueling button 197 that can be manually actuated or pressed by the vehicle operator to initiate refueling. For example, as described in greater detail below, in response to the vehicle operator actuating the refueling button 197, the fuel tank in the vehicle can be depressurized, such that refueling can be performed.

[0034] As known in the art, the control system 190 can be communicatively coupled to other vehicles or infrastructure using appropriate communication technology. For example, the control system 190 can be coupled to other vehicles or infrastructure via a wireless network 131, which can include Wi-Fi, Bluetooth, a type of cellular service, a wireless data transfer protocol, etc. The control system 190 can broadcast (and receive) information regarding 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) technology. The communications and information exchanged between vehicles can be directly between vehicles or can be multi-hop. In some instances, long-range communications (e.g., WiMax) can be used instead of or in conjunction with V2V or V2I2V to extend the coverage area several miles. In other instances, the vehicle control system 190 can be communicatively coupled to other vehicles or infrastructure via the wireless network 131 and the Internet (e.g., the cloud), as is known in the art.

[0035] The vehicle system 100 can also include an on-board navigation system 132 (e.g., a global positioning system) with which a vehicle operator can interact. The navigation system 132 can include one or more position sensors for assisting in estimating vehicle speed, vehicle height, vehicle location / position, etc. This information can be used to infer engine operating parameters, such as local atmospheric pressure. As noted above, the control system 190 can be further configured to receive information via the Internet or other communication network. Information received from the GPS can be cross-referenced with information available via the Internet to determine local weather conditions, local traffic rules, etc.

[0036] Figure 2A A schematic of a vehicle system 206 is shown. It can be appreciated that the vehicle system 206 can include the same vehicle system as the vehicle system 100 depicted. Figure 1 The vehicle system 206 includes an engine system 208 coupled to an emissions control system 251 and a fuel system 218. It can be appreciated that the fuel system 218 can include the same fuel system as the fuel system 218 of the vehicle system 100 depicted. Figure 1The depicted fuel system 140 is identical to the fuel system. The emissions control system 251 includes a fuel vapor container or canister 222, which can be used to capture and store fuel vapor. The engine system 208 can 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 223 includes a throttle valve 262 in fluid communication with an engine intake manifold 244 via an intake passage 242. In some examples, the throttle valve 262 can include an electronic throttle valve, which can be commanded to a desired position via the controller 212. Further, the engine intake 223 can include an air box and filter (not shown) located upstream of the throttle valve 262. The engine exhaust system 225 includes an exhaust manifold 248 leading to an exhaust passage 235, which directs exhaust gases to atmosphere. The exhaust passage can lead to one or more exhaust aftertreatment devices (e.g., 226, 229, 236) as well as a reductant delivery and storage system, such as a diesel exhaust fluid (DEF) system 238. In some examples, the exhaust passage can include an exhaust tuning valve 299, which can include, for example, a butterfly valve, and can be controlled via the controller to a fully open or fully closed position or somewhere in between.

[0037] The exhaust aftertreatment devices can be arranged in various sequences and / or combinations along the exhaust passage 235. For example, a diesel oxidation catalyst (DOC) 226 can be followed downstream by a selective catalytic reduction (SCR) catalyst 229. In some examples, a nitrogen oxides sensor (NOx sensor) 298 can be positioned downstream of the SCR and can be configured to measure NOx concentration. The SCR catalyst 229 can be followed downstream by a diesel particulate filter (DPF) 236. It should be appreciated that, Figure 2A The depicted emissions control devices of the exhaust system 225 are exemplary in nature. Various other emissions control devices and configurations can be included in the engine exhaust system 225. For example, the exhaust system 225 can include an SCR catalyst followed only by a DPF. In another example, the exhaust system 225 can include only an SCR catalyst. In yet another example, a DPF can be located upstream of an SCR catalyst, or a combined DPF / SCR catalyst can be used.

[0038] The engine exhaust system 225 can also include a reductant delivery and / or storage system, such as a DEF system 238. DEF can be a liquid reductant, such as a mixture of urea and water, which is stored in a storage container, such as a storage tank. In one example, the DEF system 238 can include a DEF tank 239 for on-board DEF storage, a DEF delivery line 240 coupling the DEF tank 239 to the exhaust passage 235 via an injector at or upstream of the SCR catalyst 229. The DEF tank 239 can have various forms, and can include a fuel filler neck 241 and a corresponding tank cap and / or cap door in the vehicle body. The fuel filler neck 241 can be configured to receive a nozzle for replenishing DEF.

[0039] The DEF system 238 can also include a first DEF injector 243 in the line 240, which injects DEF into the exhaust gas upstream of the SCR catalyst 229. The first DEF injector 243 can be used to control the timing and amount of DEF injection via the control system 214. More specifically, the first DEF injector 243 can include a first DEF injector valve 292. The DEF injector valve 292 can be configured as an active solenoid valve, which can be actuated open and closed, for example, via commands from the control system 214. The DEF system 238 can also include a DEF pump 246. The DEF pump 246 can be used to pressurize and deliver DEF into the line 240. The DEF system 238 can also include a DEF line heater 247, which heats the DEF line 240. For example, the DEF line heater 247 can heat DEF fluid en route to the DEF pump at low temperatures, in order to maintain DEF fluid viscosity. The DEF line heater 247 can be a resistive heater or various other configurations. The DEF line heater 247 can be coupled to the energy storage device 150, which can include a battery, and can be activated and controlled, for example, via the control system 214.

[0040] It can be appreciated that by injecting DEF into hot exhaust gas upstream of the SCR, where the DEF includes a mixture of urea and water, the urea can decompose into ammonia gas (NH3) in the hot exhaust gas and can be absorbed by the SCR device. The ammonia gas then reduces NOx into nitrogen gas in the presence of the SCR catalyst. Thus, it can be appreciated that in some examples, a NOx sensor can be used to infer when and how much DEF is injected into the exhaust gas in order to effectively reduce NOx emissions via filling the SCR with ammonia gas.

[0041] It should be appreciated that other components such as various valves and sensors can be included in the engine. For example, an atmospheric pressure sensor 213 can be included in the engine intake. In one example, the atmospheric pressure sensor 213 can be a manifold air pressure (MAP) sensor and can be coupled to the engine intake downstream of the throttle 262. The atmospheric pressure sensor 213 can rely on a partially throttled or wide open throttle condition in order to accurately determine BP, for example when the throttle 262 is open more than a threshold amount.

[0042] A humidity sensor 258 can be positioned in the engine intake downstream of the throttle 262. For example, the humidity sensor can be positioned to determine the humidity of the intake air flowing through the intake passage 242. In one example, the humidity sensor 258 can measure both 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 air flow) can be determined. To measure the relative humidity, a dew point sensor can be used (e.g., using a chilled mirror) or a wet bulb / dry bulb sensor. In other examples, the absolute humidity can be measured by a capacitive sensor, and the temperature and / or pressure of the air can be estimated or measured in order to calculate the relative humidity and / or specific humidity.

[0043] In particular, the engine control system tends to want to know the specific humidity, e.g., the humidity ratio of the air. In other words, the engine control system wants to know how much of the air is water vapor (or some other dilutant). Some engine humidity sensors measure the absolute humidity, e.g., the mass of water in a volume of air. In many cases, the humidity sensor can measure the absolute humidity, convert it to relative humidity via selected measurements and assumptions, send the relative humidity data to the controller 212, which reconverts to absolute humidity and then to specific humidity. In order to make this conversion, both the pressure and temperature at the point of measurement can be measured or inferred. Thus, in some examples, an atmospheric pressure sensor 213 and a temperature sensor 260 can be included near the humidity sensor 258.

[0044] In some examples, the engine system 208 can include an engine speed sensor 265. The engine speed sensor 265 can be attached to the crankshaft (not shown) of the engine 110 and can communicate the engine speed to the controller 212. In some examples, the engine system 208 can include an engine torque sensor 267 and can be coupled to the crankshaft (not shown) of the engine 110 to measure the torque generated by the engine. In one example, the engine torque sensor can be used to indicate whether one or more engine cylinders are functioning as desired or whether there are undesirable issues with the engine cylinders, such as carbon deposits on the cylinder intake / exhaust valves, among others.

[0045] The engine system 208 can also include an exhaust gas recirculation (EGR) system 249 that receives at least a portion of the exhaust flow from the engine 110 and returns exhaust gas to the engine intake manifold 244 downstream of the throttle 262. In some cases, the EGR system 249 can be used to adjust the temperature and / or dilution of the air and fuel mixture within the combustion chamber, thereby providing a method of controlling ignition timing during some combustion modes. Additionally, in certain cases, a portion of the combustion gases can be retained or trapped in the combustion chamber by controlling exhaust valve timing. The EGR system 249 is shown as forming a common EGR passage 250 from the exhaust passage 235 to the intake passage 242.

[0046] In some examples, the exhaust system 225 can also include a turbocharger (not shown) that includes a turbine and a compressor coupled on a common shaft. The turbine can be coupled within the exhaust passage 235, while the compressor can be coupled within the intake passage 242. The turbine blades can be caused to rotate about the common shaft when a portion of the exhaust flow expelled from the engine 110 impinges on the turbine blades. The compressor can be coupled to the turbine such that the compressor can be actuated when the turbine blades are caused to rotate. When actuated, the compressor can then direct pressurized fresh air to the intake manifold 244, which can then be directed to the engine 110. In systems where the EGR passage 250 is coupled to the engine exhaust 225 upstream of the turbine and to the intake passage 242 downstream of the compressor, the EGR system can be considered a high pressure EGR system. The EGR passage can alternatively be coupled downstream of the turbine and upstream of the compressor (a low pressure EGR system). It can be appreciated that the systems and methods discussed herein can be applied to either a high pressure EGR system or a low pressure EGR system without departing from the scope of the present disclosure.

[0047] The EGR valve 253 can be coupled within the EGR passage 250. The EGR valve 253 can be configured as a solenoid valve that can be actuated to allow exhaust gas to flow into the intake manifold 244. The portion of the exhaust flow expelled by the engine 110 that is allowed to pass through the EGR system 249 and returned to the engine 110 can be metered by the measured actuation of the EGR valve 253, which can be adjusted by the controller 212. The actuation of the EGR valve 253 can be based on various vehicle operating parameters and a calculated total EGR flow rate.

[0048] One or more EGR coolers 254 can be coupled within the EGR passage 250. The EGR coolers 254 can be used to reduce the overall temperature of the EGR flow stream before passing the stream to the intake manifold 244, where it can be combined with fresh air and directed to the engine 110. The EGR passage 250 can include one or more flow restriction regions 255. One or more pressure sensors 256 can be coupled at or near the flow restriction regions 255. The diameter of the flow restriction regions can thus be used to determine the overall volumetric flow rate through the EGR passage 250.

[0049] An air intake system hydrocarbon trap (AIS HC) 257 can be placed in the intake manifold of the engine 110 to adsorb fuel vapors emitted from unburned fuel in the intake manifold, puddled fuel from deteriorated fuel injectors, and / or fuel vapors in the crankcase ventilation emissions during engine shutdown. The AIS HC can include a stack of successive laminar polymer sheets impregnated with HC vapor adsorption / desorption material. Alternatively, the adsorption / desorption material can be packed in the areas between the polymer sheet layers. The adsorption / desorption material can include one or more of carbon, activated carbon, zeolite, or any other HC adsorption / desorption material. The captured vapors can be passively desorbed from the AIS HC and combusted in the engine 110 as the engine is operated, causing a vacuum in the intake manifold and resulting air flow through the AIS HC 257. Thus, during engine operation, intake fuel vapors are stored and desorbed from the AIS HC 257. In addition, 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 purged, and the trap can reduce evaporative emissions from the intake passage even when the engine 110 is shut down.

[0050] The fuel system 218 can include a fuel tank 220 coupled to a fuel pump system 221. It can be appreciated that the fuel tank 220 can include a fuel tank heater, a fuel tank pressure regulator, and / or a fuel tank vent filter as described above in connection with the fuel system 216 of the engine 100. Figure 1The fuel tank 220 can contain a variety of fuel blends, including fuels with a range of alcohol concentrations, such as various gasoline-ethanol blends, including E10, E85, gasoline, and the like, as well as combinations thereof. A fuel level sensor 234 located in the fuel tank 220 can provide an indication of the fuel level to the controller 212 ("fuel level input"). As depicted, the fuel level sensor 234 can include a float connected to a variable resistor. Alternatively, other types of fuel level sensors can be used.

[0051] Vapor generated in the fuel system 218, prior to being purged to the engine intake 223, can be directed to a vapor emission control system 251 via a vapor recovery line 231, which includes a fuel vapor canister 222. The vapor recovery line 231 can be coupled to the fuel tank 220 via one or more conduits, and can include one or more valves for isolating the fuel tank under certain conditions. For example, the vapor recovery line 231 can be coupled to the fuel tank 220 via one or more or combinations of conduits 271, 273, and 275.

[0052] Further, in some examples, one or more fuel tank vent valves can be positioned in the conduits 271, 273, or 275. Among other functions, the fuel tank vent valves can allow the fuel vapor canister of the emission control system to be maintained at a low pressure or vacuum without increasing the rate of fuel evaporation from the fuel tank (which would otherwise occur if the fuel tank pressure were to decrease). For example, the conduit 271 can include a grade vent valve (GVV) 287, the conduit 273 can include a fill limit vent valve (FLVV) 285, and the conduit 275 can include a grade vent valve (GVV) 283. Further, in some examples, the recovery line 231 can be coupled to a fuel fill system 219. In some examples, the fuel fill system can include a fuel tank cap 205 for sealing the fuel fill system from the atmosphere. The fuel fill system 219 is coupled to the fuel tank 220 via a fuel filler tube or port 211.

[0053] Further, the refueling system 219 can include a refueling lock 245. In some examples, the refueling lock 245 can be a fuel tank flap locking mechanism. The fuel tank flap locking mechanism can be configured to automatically lock the fuel tank flap in a closed position so that the fuel tank flap cannot be opened. For example, when the pressure or vacuum in the fuel tank is greater than a threshold, the fuel tank flap 205 can remain locked via the refueling lock 245. In response to a refueling request, such as a request initiated by a vehicle operator, the fuel tank can be depressurized and the fuel tank flap unlocked after the pressure or vacuum in the fuel tank falls below the threshold. The fuel tank flap locking mechanism can be a latch or clutch that, when engaged, prevents removal of the fuel tank flap. The latch or clutch can be electrically locked, for example, by a solenoid, or mechanically locked, for example, by a pressure diaphragm.

[0054] In some examples, the refueling lock 245 can be a fuel filler tube valve located at the mouth of the fuel filler tube 211. In such examples, the refueling lock 245 can not prevent removal of the fuel tank flap 205. Instead, the refueling lock 245 can prevent insertion of a refueling pump into the fuel filler tube 211. The filler tube valve can be electrically locked, for example, by a solenoid, or mechanically locked, for example, by a pressure diaphragm.

[0055] In some examples, the refueling lock 245 can be a refueling door lock, such as a latch or clutch, that locks a refueling door located in a body panel of the vehicle. The refueling door lock can be electrically locked, for example, by a solenoid, or mechanically locked, for example, by a pressure diaphragm.

[0056] In examples in which the refueling lock 245 is locked using an electric mechanism, the refueling lock 245 can be unlocked by a command from the controller 212, for example, when the fuel tank pressure falls below a pressure threshold. In examples in which the refueling lock 245 is locked using a mechanical mechanism, the refueling lock 245 can be unlocked via a pressure gradient, for example, when the fuel tank pressure falls to atmospheric pressure.

[0057] The emissions control system 251 can include one or more emissions control devices, such as one or more fuel vapor filters 222 filled with an appropriate adsorbent 286b configured to temporarily capture fuel vapor (including evaporated hydrocarbons) and “run losses” (i.e., fuel evaporated during vehicle operation) during fuel tank refilling operations. In one example, the adsorbent 286b used is activated carbon. The emissions control system 251 can also include a filter vent path or vent line 227 that can direct gas from the filter 222 to vent to atmosphere when storing or capturing fuel vapor from the fuel system 218.

[0058] The canister 222 can include a buffer zone 222a (or buffer region), each containing adsorbent. As shown, the volume of the buffer zone 222a can be less than (e.g., a fraction of) the volume of the canister 222. The adsorbent 286a in the buffer zone 222a can be the same or different than the adsorbent in the canister (e.g., both can include charcoal). The buffer zone 222a can be positioned within the canister 222 such that during canister loading, fuel tank vapors are first adsorbed within the buffer zone, and then when the buffer zone is saturated, additional fuel tank vapors are adsorbed in the canister. In contrast, during canister purging, fuel vapors are first desorbed from the canister (e.g., to a threshold amount), and then from the buffer zone. In other words, the loading and unloading of the buffer zone is not linear with the loading and unloading of the canister. Thus, the effect of the canister buffer zone is to dampen any fuel vapor peaks flowing from the fuel tank to the canister, thereby reducing the likelihood of any fuel vapor peaks entering the engine. One or more temperature sensors 232 can be coupled to the canister 222 and / or within the canister. When fuel vapors are adsorbed by the adsorbent in the canister, heat is generated (heat of adsorption). Likewise, when fuel vapors are desorbed by the adsorbent in the canister, heat is consumed. In this way, the adsorption and desorption of fuel vapors by the canister can be monitored and estimated based on temperature changes within the canister.

[0059] The vent line 227 can also allow fresh air to be drawn into the canister 222 when stored fuel vapors are purged from the fuel system 218 to the engine intake 223 via the purge line 228 and purge valve 261. For example, the purge valve 261 can be normally closed, but can be opened under certain conditions such that a vacuum from the engine intake manifold 244 is provided to the fuel vapor canister for purging. In some examples, the vent line 227 can include an air filter 259 disposed therein upstream of the canister 222.

[0060] In some examples, the flow of air and vapors between the canister 222 and atmosphere can be regulated by a canister vent valve 297 coupled within the vent line 227. When included, the canister vent valve 297 can be a normally open valve such that a fuel tank isolation valve 252 (FTIV) can control the venting of the fuel tank 220 to atmosphere. The FTIV 252 can be positioned between the fuel tank and the fuel vapor canister 222 within the conduit 278. The FTIV 252 can be a normally closed valve that, when open, allows fuel vapors to be discharged from the fuel tank 220 to the fuel vapor canister 222. The fuel vapors can then be discharged to atmosphere, or purged to the engine intake system 223 via the canister purge valve 261. In some examples, the FTIV can not be included, while in other examples, the FTIV can be included.

[0061] By selectively adjusting various valves and solenoids, the fuel system 218 can be operated by the controller 212 in a variety of modes. It can be appreciated that the control system 214 can include the same control system as the control system 190 depicted above. For example, the fuel system can be operated in a fuel vapor storage mode (e.g., during a fuel tank refueling operation and with the engine not combusting air and fuel), where the controller 212 can open the isolation valve 252 (when included) while closing the canister purge valve (CPV) 261 to direct refueling vapors into the canister 222 while preventing fuel vapors from being directed into the intake manifold. Figure 1

[0062] As another example, the fuel system can be operated in a refueling mode (e.g., when a vehicle operator requests a fuel tank refueling), where the controller 212 can open the isolation valve 252 (when included) while maintaining the canister purge valve 261 closed to depressurize the fuel tank before allowing fuel to be added thereto. Thus, the isolation valve 252 (when included) can remain open during the refueling operation to allow refueling vapors to be stored in the canister. After refueling is complete, the isolation valve can be closed.

[0063] As yet another example, the fuel system can be operated in a canister purge mode (e.g., after an emissions control device light-off temperature has been reached and with the engine combusting air and fuel), where the controller 212 can open the canister purge valve 261 while closing the isolation valve 252 (when included). In this mode, a vacuum generated by the intake manifold of the operating engine can be used to draw fresh air through the vent 227 and through the fuel vapor canister 222 to purge stored fuel vapors into the intake manifold 244. In this mode, the purged fuel vapors from the canister are combusted in the engine. Purging can continue until the amount of fuel vapors stored in the canister is below a threshold value.

[0064] The controller 212 can include a portion of the control system 214. In some examples, the control system 214 can be separate from the controller 212. In some examples, the control system 214 can be integrated with the controller 212. Figure 1 ​The control system 190 shown is the same. The control system 214 is shown as receiving information from a plurality of sensors 216 (various instances of which are described herein) and sending control signals to a plurality of actuators 281 (various instances of which are described herein). As one example, the sensors 216 can include an exhaust gas sensor 237, a temperature sensor 233, a pressure sensor 291, a pressure sensor 282, and a canister temperature sensor 232 located upstream of the emission control device 270. Other sensors such as pressure, temperature, air-fuel ratio, and composition sensors can be coupled to various locations in the vehicle system 206. As another example, the actuators can include a throttle valve 262, a fuel tank isolation valve 252, a canister purge valve 261, and a canister vent valve 297. The control system 214 can include a controller 212. The controller can receive input data from various sensors, process the input data, and trigger actuators in response to the processed input data based on instructions or code in which it is programmed corresponding to one or more programs. The controller is described herein with respect to the control programs described herein. Figures 4-6 An example control program is described.

[0065] In some examples, the controller can be placed in a reduced power mode or hibernate mode in which the controller maintains only basic functions and operates with lower battery consumption than a corresponding wake mode. For example, the controller can be placed in a hibernate mode after a vehicle off event in order to perform a diagnostic program for a duration of time after the vehicle off event. The controller can have a wake input that allows the controller to return to a wake mode based on input received from one or more sensors. For example, opening of a vehicle door can trigger a return to a wake mode. In other examples, the controller can need to wake in order to perform such a method. In such examples, the controller can remain awake for a period of time referred to as a time period in which the controller maintains wake to perform extended off functions so that the controller can wake to perform a diagnostic program. In another example, the wake capability can enable the circuit to wake the controller when a diagnostic is requested (e.g., when a humidity sensor diagnostic is requested, or when conditions for performing such a diagnostic are met).

[0066] An undesirable evaporative emission detection procedure can be performed by the controller 212 intermittently for the fuel system 218 and / or the evaporative emission system 251 to confirm the absence of undesirable evaporative emissions in the fuel system and / or the evaporative emission system. Thus, the evaporative emission detection procedure can be performed using an engine off natural vacuum (EONV) at engine off (engine off testing) due to changes in temperature and pressure at the fuel tank after engine off and / or a vacuum supplemented with a vacuum pump. Alternatively, the evaporative emission detection procedure can be performed while the engine is running by operating a vacuum pump and / or using engine intake manifold vacuum. In some configurations, a canister vent valve (CVV) 297 can be coupled within the vent line 227. The CVV 297 can be used to regulate the flow of air and vapor between the canister 222 and the atmosphere. The CVV can also be used for diagnostic procedures. When included, the CVV can be opened during fuel vapor storage operations (e.g., during refueling of the fuel tank and during periods when the engine is not running) so that purge air of fuel vapor after having passed through the canister can be pushed out to the atmosphere. Likewise, during a purge operation (e.g., during canister regeneration and while the engine is running), the CVV can be opened to allow fresh air flow to strip fuel vapor stored in the canister. In some examples, the CVV 297 can be a solenoid valve, where opening or closing of the valve is performed via actuation of a canister vent solenoid. In particular, the canister vent valve can be open, which closes upon actuation of the canister vent solenoid. In some examples, the CVV 297 can be configured as a latching solenoid valve. In other words, when the valve is placed in a closed configuration, it latches closed without requiring additional current or voltage. For example, the valve can be closed with a 100 ms pulse, and subsequently opened at a later point in time with another 100 ms pulse. In this way, battery power required to maintain the CVV closed is reduced. In particular, the CVV can be closed at vehicle shutdown, thereby maintaining battery power while maintaining the fuel emission control system sealed from the atmosphere.

[0067] Turning now to Figure 2B , an example of a vehicle system 293 is shown. It can be appreciated that Figure 2B most of the components of the vehicle system 293 are the same as those described for Figure 2A the vehicle system 206 depicted. Accordingly, Figure 2A like components between Figure 2B are designated with like reference numerals, and the description thereof will not be repeated here for the sake of brevity.

[0068] As described above, in the exemplary vehicle system 293 of Figure 2B the engine exhaust system can include a DEF system 238B. The DEF system 238B can include the same components as the DEF system 238A described above, except that the DEF system 238B can also include a second DEF delivery line 294 that is sourced from the DEF delivery line 240.Figure 2A The DEF system 238 discussed in the middle has identical components. A second DEF delivery line 294 can couple the DEF tank 239 to the intake manifold 244 via a second DEF injector 295. The second DEF injector 295 can include a second DEF injector valve 296, which can be configured as an active solenoid valve that can be actuated open and closed, for example, via commands from the control system 214. Thus, as will be discussed in detail below, there can be vehicle operating conditions or situations in which it can be beneficial to inject DEF into the intake manifold. Alternatively, there can be other situations in which it can be beneficial to inject DEF into the exhaust passage 235. Importantly, it can be understood that in situations such as Figure 2B in which DEF can be injected into the intake manifold 244 and / or the exhaust passage 235, DEF can be injected into the intake manifold without also injecting DEF into the exhaust passage 235. Alternatively, DEF can be injected into the exhaust passage 235 without also injecting DEF into the intake manifold 244. Still further, there can be instances in which DEF can be injected into both the intake manifold 244 and the exhaust passage 235 simultaneously or nearly simultaneously. Detailed examples of injecting DEF into one or more of the intake manifold 244 and / or the exhaust passage 235 for particular diagnostic procedures will be discussed below with respect to Figures 4-6 .

[0069] Briefly, in one example, DEF can be injected into the intake manifold 244 as engine combustion air and fuel is injected, in order to draw the DEF into one or more cylinders of the engine, such that carbon deposits (e.g., on the top of the cylinder pistons or on the intake / exhaust valves) can be cleaned. In some examples, when DEF is drawn into one or more cylinders of the engine, the air-to-fuel ratio can be adjusted to a rich air-to-fuel ratio to compensate for the injected DEF. Importantly, this cleaning of carbon deposits can be performed on-board and on-demand. More specifically, as discussed, DEF can include a mixture of urea and water (urea and water components). Thus, when a mixture of fuel, air, and DEF is introduced into one or more engine cylinders and ignited, the water component of the DEF can turn into vapor (e.g., become vaporized), which can effectively clean the carbon deposits. DEF can be injected into the intake manifold during an engine idle state. In some examples, the engine idle state can include a key-off event in which the controller is maintained in an awake state to reduce carbon build-up, and in which the controller enters a sleep after completing the test. In such examples, it can be understood that the DEF injected into the intake manifold can include a threshold amount that is less than the amount of fuel provided to the engine during the injection of DEF into the intake manifold.

[0070] Another example includes a method including, in a first operating condition of a vehicle, the first operating condition including a degradation of one or more cylinders of an engine and an absence of an indication of the indicated degradation in an EGR system, injecting DEF into an intake manifold of the engine with the exhaust gas recirculation valve closed to mitigate the degradation of the one or more cylinders. In a second operating condition of the vehicle, the second operating condition including a degradation in the EGR system and an absence of an indication of the degradation in the one or more cylinders and / or an indication of the degradation in the one or more cylinders of the engine, injecting diesel exhaust fluid into the intake manifold of the engine with the EGR valve open to mitigate the degradation of the exhaust gas recirculation system. In the first operating condition, the DEF is injected into the intake manifold as the engine combusts air and fuel, and can further include stopping the injection of the DEF into the intake manifold in response to an indication that the degradation of the one or more engine cylinders has been mitigated, which can include an indication that carbon buildup associated with the one or more engine cylinders has been reduced or removed. In the second operating condition, the DEF can be injected into the intake manifold as the engine rotates without fuel in a forward direction for a predetermined duration. Upon expiration of the predetermined duration, the engine can be started to combust air and fuel, with one cylinder not receiving fuel, and the injection of the DEF into the intake manifold is maintained with the EGR valve open as the engine combusts air and fuel. The injection of the DEF can be stopped, and the EGR valve can be closed in response to an indication that the degradation in the EGR system has been mitigated. Mitigating the degradation in the EGR system can include reducing or removing carbon buildup in an EGR passage of the EGR system and / or removing carbon buildup associated with the EGR valve. In this example, in the second condition, it can be understood that the one engine cylinder not receiving fuel does not include the one or more cylinders of the engine having the indicated degradation. It can be understood that the indication of the degradation in the EGR system is discussed herein in response to a flow in the EGR system being lower than a desired flow at the EGR valve open under a predetermined operating condition of the vehicle, and / or in response to the flow in the EGR system being higher than a desired flow under a condition of the EGR valve closed.

[0071] In another example, consider a situation where EGR flow is lower than expected or desired. This low flow EGR can be due to carbon deposits on an EGR valve (e.g., 253) or in an EGR passage (e.g., 250). In this example, DEF can be injected into an intake manifold while the engine is rotating un-fueled in a forward or default direction (e.g., without combustion of air and fuel) with the EGR valve open to direct the liquid DEF into the EGR passage (e.g., 250). After directing the DEF into the EGR passage, the engine can be started to combust air and fuel so that heat can be generated in the exhaust and EGR passages. With the EGR valve open, operating the engine to combust air and fuel to heat the DEF can cause steam from the water component of the DEF to effectively clean the carbon deposits associated with the EGR valve. In other words, after directing diesel exhaust fluid to the EGR system (e.g., to the EGR passage), the engine can be operated to vaporize the DEF directed to the EGR system. Further, when the engine is started to combust air and fuel, one engine cylinder can not be started (fuel is not provided to the deactivated cylinder), and thus the one deactivated engine cylinder can be used as a route for directing DEF into the EGR passage, with DEF continuing to be injected into the intake manifold after the engine is started to combust air and fuel. This example can include a condition where an oxidation catalyst (e.g., 226) is above a threshold temperature (where the threshold temperature can include a temperature at which any DEF directed through the oxidation catalyst at this point can be vaporized).

[0072] In another example, a third operating condition of the vehicle can include injecting DEF into an intake manifold of an engine of the vehicle and directing the DEF to an EGR system, and a fourth operating condition can include injecting DEF into an exhaust passage of the vehicle and directing the DEF to the EGR system. In this example, both the third operating condition and the fourth operating condition can include vaporizing the DEF in response to directing the DEF to the EGR system. In this example, the third operating condition can include a temperature of an oxidation catalyst (e.g., 226) located upstream of an injection site for injecting DEF into the exhaust passage being greater than a threshold temperature, and the fourth operating condition can include the temperature of the oxidation catalyst being less than the threshold temperature. In this example, the threshold temperature can include a temperature at which DEF directed through the oxidation catalyst at this point causes the DEF to vaporize. In the example, in the third operating condition, the engine can be rotating un-fueled in a forward direction, and in the fourth operating condition, the DEF can be directed to the EGR system by rotating the engine un-fueled in a reverse direction. In both the third condition and the fourth condition, vaporizing the DEF includes starting the engine to combust air and fuel so that engine exhaust heat is directed to the EGR system. Further, the third operating condition can include a key-off event, and the fourth operating condition can include a key-on event.

[0073] In another example, a fifth operating condition can include conditions in which carbon accumulation is indicated in the EGR system and in which the temperature of the oxidation catalyst (e.g., 226) is greater than a threshold value, and a sixth operating condition can include conditions in which carbon accumulation is indicated in the EGR system, in which the temperature of the oxidation catalyst is less than the threshold temperature. In the fifth operating condition, the engine can be operated in one mode to reduce carbon accumulation by injecting DEF into the intake manifold and directing the DEF to the EGR system, while in the sixth operating condition, the engine can be operated in another mode to reduce carbon accumulation by injecting DEF into the exhaust passage and directing the DEF to the EGR system. In such an example, one mode (the fifth operating condition) can include rotating the engine in a forward direction un-fueled via the motor when DEF is injected into the intake manifold, while the other mode (the sixth operating condition) includes rotating the engine in a reverse direction un-fueled via the motor when DEF is injected into the exhaust passage. In both the fifth and sixth operating conditions, the EGR valve can be commanded to open. Further, in both the fifth and sixth operating conditions, in response to DEF being directed to the EGR system, the DEF is evaporated by starting the engine to combust air and fuel to reduce carbon accumulation. In the fifth operating condition, one cylinder can be maintained deactivated, while in the sixth operating condition, all cylinders can be started to combust air and fuel. Further, in the fifth condition, DEF can continue to be injected into the intake manifold while the engine combusts air and fuel.

[0074] In another example in which EGR flow is lower than expected or desired with the EGR valve open or greater than expected with the EGR valve closed, another method can be used to clean carbon deposits in the EGR valve (e.g., 253). In some examples, such a method can be used in response to a situation in which the vehicle is not equipped with a DEF line to enable DEF to be injected into the intake manifold (e.g., 244), but as Figure 2AIn the depicted example, DEF can be injected into an exhaust passage (e.g., 335). In such an example, liquid DEF can be injected into the exhaust passage and directed into the EGR passage (e.g., 250) by having the engine rotate in a reverse direction without fueling (e.g., without combusting air and fuel). More specifically, by rotating the engine in a reverse direction, a vacuum can be created in the exhaust system while a pressure can be created in the intake manifold. For example, when the engine is rotated 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) evacuates the cylinder to the intake manifold. If the EGR valve (e.g., 253) is open, then liquid DEF can be directed to the EGR passage. Once the liquid DEF is present in the EGR passage, the engine can be started to combust air and fuel, and where the engine is rotated in a default direction. By operating the engine to combust air and fuel, hot exhaust gas can be directed to the EGR passage, where the water content of the DEF can be vaporized, which can be used to clean carbon deposits in the EGR valve.

[0075] In another example, a method can include injecting DEF into an exhaust passage of a vehicle to fill an SCR catalyst located in the exhaust passage with ammonia gas in a seventh operating condition, and injecting DEF into an exhaust passage of an engine of the vehicle to reduce carbon build-up in an EGR system in an eighth operating condition. In such an example, the seventh operating condition can include a temperature of an oxidation catalyst (e.g., 226) located upstream of an injection site for injecting DEF into the exhaust passage being above or below a threshold temperature (the threshold temperature including a temperature above which DEF directed through the oxidation catalyst can vaporize). The eighth operating condition can include a condition in which the temperature of the oxidation catalyst is below the threshold temperature. In the example, the seventh operating condition can include the engine combusting air and fuel during injection of the DEF, while the eighth operating condition can include the engine not combusting air and fuel during injection. Further, the eighth operating condition can include rotating the engine in a reverse direction for a predetermined duration to direct the DEF into the EGR system during injection, and in response to expiration of the predetermined duration, stopping the engine from rotating in the reverse direction and starting the engine to combust air and fuel. In some examples, as a level of condensate stored in an EGR cooler located in the EGR system decreases, a rotational speed (RPM) of the engine can be increased and / or an amount of DEF injected into the exhaust passage can be increased, or vice versa. Still further, the seventh operating condition can be independent of whether an EGR valve is open or closed, while the eighth operating condition can include commanding the EGR valve to open just prior to (within 2 seconds or less) or in conjunction with the DEF being injected into the exhaust passage. In some examples, the EGR valve can be commanded to open just after (within 2 seconds or less) the DEF is injected into the exhaust passage.

[0076] In yet another example, the ninth operating condition can include an on event and an indication of carbon build-up in the EGR system, where the ninth operating condition can include commanding the EGR valve to open, duty cycling the first DEF injection valve (e.g., 292), and un-fueled reverse rotating the engine as a function of condensate level in the EGR cooler (e.g., increasing engine speed and / or increasing the duty cycle of the injection when the condensate level decreases, or decreasing engine speed and / or decreasing the duty cycle of the injection when the condensate level increases). Such action can direct DEF to the EGR system, where, after a predetermined duration of the directing, the ninth operating condition can include stopping the duty cycling of the first DEF injection valve and stopping the un-fueled reverse rotating of the engine, and starting the engine to combust air and fuel to vaporize the DEF directed to the EGR system. In a tenth operating condition, the first DEF injection valve can be duty cycled with the engine combusting air and fuel to fill the SCR catalyst with ammonia. The ninth operating condition can include the temperature of the oxidation catalyst being below a threshold temperature, and the tenth operating condition can be independent of the temperature of the oxidation catalyst.

[0077] In each of the above examples, it can be appreciated that when the engine is un-fueled rotating in a forward direction, it can include a default direction or the same direction as the engine rotates when combusting air and fuel. In such a case, a vacuum can be created in the intake manifold of the engine, while a pressure can be created in the exhaust system. Alternatively, when the engine is un-fueled reverse rotating, a vacuum can be created in the exhaust system of the engine, while a pressure can be created in the intake manifold.

[0078] The above example methods will be described in detail below with respect to the methods depicted in Figures 4-6 FIGS. 1-3.

[0079] As discussed, the above example methods can include un-fueled rotating the engine in a forward (e.g., default) or reverse direction. To un-fueled rotate the engine in a forward or reverse direction, a vehicle motor (e.g., 120) can be used that uses electrical power supplied via an energy storage device (e.g., 150), such as a battery.

[0080] Accordingly, turning to Figures 3A-3B they show an example circuit 300 that can be used to reverse the rotational orientation of an electric motor. The circuit 300 schematically depicts an H-bridge circuit that can be used to run a motor 310 in a first (forward) direction and, alternatively, in a second (reverse) direction. The circuit 300 includes a first (LO) side 320 and a second (HI) side 330. The side 320 includes transistors 321 and 322, while the side 330 includes transistors 331 and 332. The circuit 300 also includes a power supply 340.

[0081] In Figure 3A which transistors 321 and 332 are activated (energized) and transistors 322 and 331 are off. In this confirmation, left lead 351 of motor 310 is connected to power source 340 and right lead 352 of motor 310 is grounded. In this manner, motor 310 can run in the forward direction. When the engine is operated in the forward direction via the motor, the engine can be in a cranking mode for initially starting combustion. Additionally and / or alternatively, when the engine is operated in the forward direction via the motor, the engine (and motor or another motor) can be in a drive mode to drive the vehicle. It can be appreciated that in some instances, the engine can be rotated in the forward (e.g., default) direction under conditions where the vehicle is stationary and only the engine is desired to be rotated or cranked without combustion.

[0082] In Figure 3B which transistors 322 and 331 are activated (energized) and transistors 321 and 332 are off. In this confirmation, right lead 352 of motor 310 is connected to power source 340 and left lead 351 of motor 310 is grounded. In this manner, motor 310 can run in the reverse direction.

[0083] Turning now to Figure 4 , a high-level flowchart of an example method 400 for performing a process of removing carbon deposits from one or more cylinders of a vehicle engine is shown. More specifically, method 400 can include injecting diesel exhaust fluid (DEF) into an intake manifold of the engine while the engine is combusting 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 carbon deposits.

[0084] Method 400 will be described with reference to the system described herein and shown in Figures 1-3B , but it should be understood that similar methods can be applied to other systems without departing from the scope of the present disclosure. Method 400 can be performed by a controller, such as controller 212 in Figures 2A-2B , and can be stored at the controller as executable instructions in a non-transitory memory. The instructions for performing method 400 and the remainder of the methods included herein can be performed by the controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference to Figure 1 and Figures 2A-2B . In accordance with the methods described below, the controller can employ actuators of the 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 (e.g., 262), etc.

[0085] Method 400 begins at 402 and can include estimating and / or measuring current operating conditions. Operating conditions can be estimated, measured, and / or inferred, and can include one or more vehicle conditions, such as vehicle speed, vehicle location, etc.; various engine conditions, such as engine state, engine load, engine speed, A / F ratio, etc.; various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc.; various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc.; and various environmental conditions, such as ambient temperature, humidity, barometric pressure, etc.

[0086] Proceeding to 404, method 400 can include indicating whether conditions are met to conduct a cylinder decarbonization diagnostic procedure. For example, conditions met for conducting a cylinder decarbonization diagnostic procedure can include an on-board power balance test that has indicated engine performance lag, indicating that one or more engine cylinders have accumulated carbon deposits. Conditions met at 404 can additionally or alternatively include a cylinder compression test that has indicated engine performance lag. Conditions met at 404 can in some instances include a shut-down condition, where engine performance lag has been indicated by a power balance test and / or a cylinder compression test. Conditions met at 404 can 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) elapsed since a previous cylinder decarbonization diagnostic. Conditions met at 404 can additionally or alternatively include an indication of a DEF level in a DEF storage tank (e.g., 241) greater than a predetermined threshold (e.g., >10%, >20%, or >30% full). If conditions are not indicated at 404 to conduct a cylinder decarbonization diagnostic, method 400 can proceed to 406. At 406, method 400 can include maintaining current vehicle operating parameters. For example, if a vehicle is operating with the engine running and a shut-down event is not indicated, current engine operating parameters can be maintained. In another example, if a vehicle is being propelled at least partially via electrical energy sourced from an on-board energy storage device, electrically powered operation can be maintained. Such examples are illustrative. Method 400 can then end.

[0087] Returning 404, if the conditions indicate that the cylinder decarbonization diagnosis is to be performed, the method 400 can proceed to 408. At 408, the method 400 can include commanding or maintaining engine combustion of air and fuel. For example, in the case where the vehicle is operating in a pure electric operating mode at shut-off, where the conditions indicate that the cylinder decarbonization diagnosis is to be performed, the engine can be started or cranked at 408 to begin combustion of air and fuel. Where the engine is already combusting air and fuel, combustion can then be maintained at step 408. Further, at 408, the engine speed can be controlled to a desired engine speed. The desired engine speed can be achieved via the controller (e.g., 212) commanding engine system actuators such as fuel injectors (e.g., 266), throttle (e.g., 262) position, etc., to control the engine speed to the desired speed. Still further, at 408, the method 400 can include maintaining controller wake-up, such that the cylinder decarbonization procedure can be performed.

[0088] Proceeding to 410, the method 400 can include periodically actuating a second DEF injector valve (e.g., 296). Specifically, by periodically actuating the second DEF injector valve, DEF fluid can be drawn from a DEF tank (e.g., 239) and into an intake manifold (e.g., 244) of the engine (e.g., 110). The DEF fluid can be drawn from the DEF tank due to an engine vacuum drawing the DEF fluid from the DEF tank, which can be generated due to the engine operating in a default direction (e.g., a forward direction). It can be appreciated that periodically actuating the second DEF injector valve can include the controller sending a signal to the second DEF injector valve, thereby commanding or actuating the second DEF injector valve to open and close. The second DEF injector valve can be periodically actuated in a manner whereby the amount of DEF injected into the intake manifold at each opening of the second DEF injector valve is a threshold amount less than the amount of fuel injected into each engine cylinder at each fuel injection. For example, the threshold amount can include 3 times less DEF than fuel, between 3 and 10 times less DEF than fuel, between 10 and 100 times less DEF than fuel, or greater than 100 times less DEF than fuel.

[0089] Proceeding to 412, the method 400 can include monitoring the engine speed. For example, the engine speed can be monitored via an engine speed sensor (e.g., 265). The engine speed can be monitored while the engine is combusting air and fuel, and at the same time DEF is being injected into the intake manifold. Proceeding to 414, the method 400 can include indicating whether the engine speed has decreased below a threshold engine speed. For example, the threshold engine speed can include an engine speed that is slightly above (e.g., 100, 200, or 500 RPM above) the engine stall speed. If it is indicated at 414 that the engine speed has decreased below the threshold engine speed, the method 400 can proceed to 416 and can include increasing the engine speed above the threshold engine speed to a desired engine speed (as discussed above in step 408 of the method 400). More specifically, the throttle (e.g., 262) can be commanded to a more open position to allow more intake air to flow to the engine, which can allow for an increased engine speed. In some examples, fuel injection to one or more engine cylinders can additionally or alternatively be increased to increase the engine speed to the desired engine speed.

[0090] If at 414 it is not indicated that the engine speed is below the threshold engine speed, or if the engine system actuator has controlled the engine speed to the desired engine speed at 416, the method 400 can proceed to 418. At 418, the method 400 can include indicating whether carbon deposits have been removed from the engine cylinders. This indication can be provided via the on-board power balance test discussed above. In other words, the controller can run the on-board power balance test while the engine is started to combust air and fuel, while DEF is injected into the intake manifold, and while the engine speed is controlled to the desired engine speed. With the DEF injected into the intake manifold, the DEF can be drawn into the engine cylinders, and when the fuel ignites in the engine cylinders, the water component of the DEF can vaporize into a vapor, which can effectively clean (e.g., decarbonize) the engine cylinders. The on-board power balance test can thus be utilized to indicate whether the engine cylinders have been effectively cleaned. More specifically, the power balance test can include measuring the engine torque via the torque sensor (e.g., 267). The power balance test can indicate that one or more of the engine cylinders is not operating as desired (e.g., the torque production of a particular cylinder is lower than the torque production via the other engine cylinders). Thus, at 418, in response to an indication that one or more of the engine cylinders is still not operating as desired, the method 400 can proceed to 419 and can include indicating whether a predetermined duration has expired. For example, if the carbon deposits are the cause of the engine performance lag (e.g., one or more of the engine cylinders is not operating as desired), the predetermined duration can include a duration in which the carbon deposits are expected to be removed from the one or more of the engine cylinders. For example, the predetermined duration can include one minute, between one minute and two minutes, between two minutes and three minutes, between three minutes and five minutes, or greater than five minutes. If at 419 the predetermined duration has not expired, the method 400 can return to 408 and can include continuing to operate the engine to combust air and fuel with the DEF injected into the intake manifold.

[0091] Alternatively, at 419, if the predetermined duration has expired, the method 400 can proceed to 421 and can include indicating that the engine is degraded. More specifically, a flag can be set at the controller indicating that a cylinder decarbonization test diagnosis was performed and that the test diagnosis was unable to correct the problem related to the one or more of the engine cylinders not operating as desired. Further, a malfunction indicator light (MIL) can be illuminated on the vehicle dashboard, alerting the vehicle operator that the vehicle needs to be serviced.

[0092] Proceeding to 423, the method 400 can include stopping the periodic operation of the second DEF injection valve. With the second DEF injection valve closed via controller command or actuation, the engine intake manifold vacuum can no longer draw DEF into the intake manifold. Proceeding to 425, the engine can be deactivated or turned off. For example, a signal can be sent to the fuel injectors (e.g., 266) via the controller to stop commanding / actuating fuel injection, and spark provided to the various engine cylinders can be interrupted (if the engine includes spark plugs for providing spark to the various cylinders).

[0093] Proceeding to 427, the method 400 can include updating vehicle operating parameters. For example, the vehicle operating parameters can be adjusted / updated to compensate for the indicated engine degradation. In one example where the vehicle system includes a hybrid electric vehicle capable of operating in a pure electric mode, the vehicle can be commanded to operate in the pure electric operating mode as frequently as possible to avoid further degradation of the engine.

[0094] Proceeding to 429, the method 400 can include putting the controller to sleep when the cylinder decarbonization diagnostic procedure has ended. The method 400 can then end.

[0095] Returning to 418, in response to an indication that carbon deposits have been removed from the engine cylinders, as indicated via the on-board power balance test, the method 400 can proceed to 431. More specifically, the power balance test can indicate that carbon deposits have been removed from the engine cylinders in response to the torque production of all of the engine cylinders being within a threshold of the expected or anticipated torque production (e.g., within 5%). The expected or anticipated torque production can include a level of torque production at a particular engine speed (e.g., RPM) where there are no carbon deposits present at the engine cylinders. At 431, the method 400 can include stopping the periodic operation of the second DEF injection valve. With the second DEF injection valve closed via controller command or actuation, the engine intake manifold vacuum can no longer draw DEF into the intake manifold. Proceeding to 433, the engine can be deactivated or turned off. For example, a signal can be sent to the fuel injectors (e.g., 266) via the controller to stop commanding / actuating fuel injection, and spark provided to the various engine cylinders can be interrupted (if the engine includes spark plugs for providing spark to the various cylinders).

[0096] Proceeding to 435, the method 400 can include updating vehicle operating parameters. For example, the vehicle operating parameters can be adjusted / updated to compensate for the indicated absence of carbon deposits on the cylinders. A flag can be set at the controller to indicate that the cylinder decarbonization test diagnostic was performed, and that the engine cylinder torque production was successfully restored to the expected or anticipated torque production.

[0097] Proceeding to 437, the method 400 can include putting the controller to sleep when the cylinder decarbonization diagnostic procedure has ended. The method 400 can then end.

[0098] While the above example method 400 depicts a method of removing carbon deposits from one or more engine cylinders in a vehicle and on-demand manner, in some examples there can be other components of the engine that can benefit from decarbonization techniques or methods. In particular, an EGR system (e.g., 249) can recirculate exhaust gas back into the intake system to reduce emissions of nitrogen oxides (NOx). Over time, soot and other carbon materials can build up on the EGR system and can clog it or can cause the EGR valve (e.g., 253) to stick open or stick closed. Thus, similar to the methods discussed above for cleaning carbon deposits in one or more engine cylinders, it is desirable that one or more methods can clean carbon deposits in an EGR system (e.g., 249).

[0099] Thus, turning now to Figure 5 , a high-level flowchart of an example method 500 for performing a process of removing carbon deposits from an EGR system is shown. More specifically, the method 500 can include injecting DEF into an intake manifold (e.g., 244) of an engine while the engine is rotating in a forward or default direction and an EGR valve is open to direct the DEF into an EGR passage. After a predetermined duration of directing the DEF into the EGR passage, the engine can be started to combust air and fuel, with one cylinder deactivated (not receiving a fuel injection). The DEF can thus continue to be directed to the EGR passage, and heat from the combustion can vaporize the water component of the DEF into steam, which can effectively clean carbon deposits from the EGR passage. Importantly, this method includes a vehicle on-board and on-demand EGR cleaning method.

[0100] The method 500 will be described with reference to the system described herein and shown in Figures 1-3B , but it should be understood that similar methods can be applied to other systems without departing from the scope of the present disclosure. The method 500 can be performed by a controller, such as the controller 212 in Figures 2A-2B , and can be stored at the controller as executable instructions in a non-transitory memory. The instructions for performing the method 500 and the remainder of the methods included herein can be performed by the controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference to Figure 1 and Figures 2A-2B . In accordance with the methods described below, the controller can employ actuators of the 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 (e.g., 262), an EGR valve (e.g., 253), etc.

[0101] Method 500 begins at 502 and can include estimating and / or measuring current vehicle operating conditions. Operating conditions can be estimated, measured, and / or inferred, and can include one or more vehicle conditions, such as vehicle speed, vehicle location, etc.; various engine conditions, such as engine state, engine load, engine speed, A / F ratio, etc.; various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc.; various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc.; and various environmental conditions, such as ambient temperature, humidity, barometric pressure, etc.

[0102] Proceeding to 504, method 500 can include determining whether a condition is satisfied to conduct an EGR clean diagnostic. A condition to conduct an EGR clean diagnostic can include an indication of low EGR flow rate monitored via a pressure sensor (e.g., 256) in the EGR passage (e.g., 250). For example, an expected EGR flow rate in the absence of carbon deposits associated with the EGR valve and / or in the EGR passage can be stored at the controller in the form of a lookup table, including expected flow rates at various engine speeds and / or other operating conditions. A low EGR flow rate can include an EGR flow rate level that differs from an expected EGR flow rate for a particular engine operating condition by a threshold value, such as by more than 5% or by more than 10%. In another example, a condition to conduct an EGR clean diagnostic can include an indication of a deteriorated EGR system, such as evidenced by an unstable idle or a stall condition in some examples.

[0103] The condition that is satisfied can additionally or alternatively include a shut down condition, where a low flow rate is indicated in the EGR passage, or where an EGR system deterioration is indicated. In some examples, the condition that is satisfied at 504 can additionally or alternatively include an indication that a threshold duration of time (e.g., 1 day, 2 days, 5 days, 10 days, 15 days, greater than 20 days but less than 30 days, etc.) has expired since a previous EGR clean diagnostic. The condition that is satisfied at 504 can additionally or alternatively include an indication that an amount of DEF stored in a DEF tank (e.g., 241) is greater than a predetermined threshold (e.g., >10%, >20%, or >30% full).

[0104] If a condition to conduct an EGR clean diagnostic is not indicated at 504, method 500 can proceed to 506. At 506, method 500 can include maintaining current vehicle operating parameters. For example, if the vehicle is operating with the engine running, such operation can be maintained. Alternatively, if the vehicle is operating in which the vehicle is propelled in whole or in part via electric power, such operating condition can be continued. Method 500 can then end.

[0105] Returning 504, in response to the condition indicating that the EGR clean diagnostic is satisfied, the method 500 can proceed to 507. At 507, the method 500 can include commanding the opening of the EGR valve (e.g., 253). For example, the controller can send a signal to the EGR valve, actuating it open. Proceeding to 508, the method 500 can include causing the engine to rotate unfueled in a default or forward direction. Specifically, the motor (e.g., 120) can be commanded via the controller to turn or rotate the engine unfueled in the default direction. In some examples, causing the engine to rotate unfueled can include causing the engine to rotate unfueled at a predetermined engine speed (engine RPM).

[0106] Proceeding to 510, the method 500 can include periodically operating a second DEF injection valve (e.g., 296). Periodically operating the second DEF injection valve can include periodically operating the second DEF injection valve to increase a predetermined amount of DEF over a predetermined duration. Accordingly, proceeding to 512, the method 500 can include indicating whether the predetermined duration has expired. If the predetermined duration has not expired, the method 500 can return to 508 and can include continuing to cause the engine to rotate unfueled in the default direction and can also include continuing to periodically operate the second DEF injection valve. Alternatively, in response to the predetermined duration expiring at 512, the method 500 can proceed to 514.

[0107] It can be appreciated that by injecting DEF into the intake manifold via the second DEF injection valve and causing the engine to rotate unfueled with the EGR valve open, the DEF can be drawn through the engine and into the EGR passage (e.g., 250).

[0108] At 514, the method 500 can include starting the engine to combust air and fuel. For example, the motor can be deactivated, and fuel injection (and spark, if the engine includes spark plugs for providing spark to individual cylinders) can be provided to the engine cylinders. The fuel (and spark, if applicable) can be controlled via the controller to control the engine speed to a desired speed. Further, at 514, starting the engine to combust air and fuel can include providing fuel (and spark, where applicable) to all but one of the engine cylinders. The cylinder that does not receive fuel (and spark, where applicable) can be referred to as a deactivated cylinder, but it can be appreciated that the deactivated cylinder is still used to open the intake and exhaust valves associated with the deactivated cylinder, while the engine otherwise combusts air and fuel. Still further, at 514, the spark provided to all but the deactivated cylinder can include a delayed spark, which can be used to increase the heat transferred to the exhaust manifold and EGR passage as compared to a spark that is not delayed. However, it can be appreciated that no spark can be provided in a diesel vehicle. It can be further appreciated that the one deactivated cylinder can include a route for delivering DEF (in addition to DEF that has been directed to the EGR passage when the engine is rotating without fueling) to the EGR passage for vaporization. Further, although not explicitly shown, the exhaust tuning valve (e.g., 299) can be controlled to a position where heat from the engine is effectively directed to the EGR passage. For example, in some instances, the exhaust tuning valve can be controlled to a fully closed configuration or can be mostly closed (e.g., 20% open or less), etc., such that engine exhaust heat is directed to the EGR passage.

[0109] Accordingly, proceeding to 516, the method 500 can include maintaining the second DEF injection valve periodically active. In some instances, the periodic activation of the second DEF injection valve at 516 can include the same rate of periodic activation of the second DEF injection valve as was performed at step 510 of the method 500. In other instances, the periodic activation of the second DEF injection valve at 516 can include periodically activating the second DEF injection valve at a rate that is greater or less than the periodic activation performed at 510. As discussed, with one cylinder deactivated, DEF can be directed to the exhaust manifold and EGR passage for vaporization. Vaporization of the DEF can thus convert the water component of the DEF to steam, which can be used to clean any deposits in the EGR passage and / or associated with the EGR valve.

[0110] Proceeding to 518, the method 500 can include maintaining the engine speed at the desired engine speed. For example, when DEF is injected into the intake manifold, even though there are deactivated cylinders that can direct DEF to the exhaust manifold and EGR passage, this can result in a drop in engine speed in some instances. Thus, to prevent a potential stall condition, the engine speed can be maintained at the 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 to enable additional air to be drawn into the intake to control the engine speed to the desired engine speed. Further, at 518, the method 500 can include controlling the engine to maintain a desired engine intake manifold vacuum to enable 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 such that the desired intake manifold vacuum is maintained.

[0111] Proceeding to 520, the method 500 can include indicating whether carbon deposits are indicated to be removed from the EGR valve and / or EGR passage. In particular, at 520, the method 500 can include monitoring the pressure in the EGR passage and indicating whether the EGR flow for a particular engine operating condition (e.g., a desired engine speed) is within a threshold (e.g., within 5%) of an expected EGR flow (e.g., without carbon deposits in the EGR passage and / or associated with the EGR valve). As noted above, a lookup table stored at the controller can include expected EGR flows as a function of engine operating conditions, and thus, such a lookup table can be queried at 520 via the controller in order to indicate whether carbon deposits have been removed from the EGR valve / EGR passage.

[0112] At 520, if carbon deposits have been removed, indicating that the EGR flow is within the threshold of the expected EGR flow, the method 500 can proceed to 522. In other words, in response to an indication that carbon deposits have been removed, the method 500 can proceed to 522. At 522, the method 500 can include commanding the EGR valve to a closed position and can also include stopping the injection of DEF into the intake manifold. More specifically, the second DEF injection valve can be commanded closed such that the periodic operation of the second DEF injection valve is stopped and DEF is no longer injected into the intake manifold.

[0113] Proceeding to 524, the method 500 can include maintaining engine startup at the desired rotational speed for a predetermined duration. Specifically, the engine can be maintained in operation to combust air and fuel in order to force any removed carbon deposits out of the exhaust port. Further, all engine cylinders can be started to combust air and fuel. In other words, the one deactivated cylinder can be provided with fuel (and spark, where applicable) such that all engine cylinders combust air and fuel. Since the EGR valve was commanded to close at step 522, deposits can thus be directed to the exhaust port instead of the EGR passage. At 524, the predetermined duration can include a duration in which any carbon deposits expected to be removed from the EGR passage and / or EGR valve can be directed to exit the exhaust port. In some examples, the predetermined duration at 524 can include 1 minute, 2 minutes, 3 minutes, 4 minutes, or 5 minutes.

[0114] Proceeding to 526, the method 500 can include stopping or deactivating the engine after an indication that the predetermined duration (524) has expired. For example, fuel (and spark, where applicable) provided to the engine cylinder can be stopped, and the engine can be rotated to a standstill. At 528, the method 500 can include updating the vehicle operating parameters. Specifically, the vehicle operating parameters can be updated to reflect an indication that the EGR valve and EGR passage are now clean or free of carbon deposits. Further, at 528, updating the vehicle operating parameters can include setting a flag at the controller that indicates that an EGR cleaning procedure was performed, and that the procedure successfully removed carbon deposits from the EGR valve and / or EGR passage. In some examples, in response to completion of the EGR cleaning procedure, the method 500 can include putting the controller to sleep. The method 500 can then end.

[0115] Returning 520, in response to an indication that carbon deposits have not been removed from the EGR valve and / or the EGR passage, the method 500 can proceed to 530. At 530, the method 500 can include indicating whether a predetermined duration has expired. The predetermined duration at 530 can include a duration in which if carbon deposits associated with the EGR valve and / or the EGR passage are the culprit behind the low EGR flow, such deposits can be expected to be removed via the EGR cleaning procedure of the method 500. Thus, if at 530 it is indicated that the predetermined duration has not expired, the method 500 can return to 514 and can include continuing to operate the engine at the desired rotational speed, with the engine combusting air and fuel, with one cylinder deactivated, and with DEF injected by periodically actuating the second DEF injection valve until it is indicated that the carbon deposits have been removed or the predetermined duration has expired. Thus, at 530, in response to an indication that the predetermined duration has expired, the method 500 can proceed to 532. At 532, the method 500 can include indicating that the EGR system is deteriorated. For example, because the procedures of the method 500 were unable to restore the flow in the EGR system to the expected flow, it can be indicated that there is some underlying cause of the low flow that cannot be remedied via the procedures of the method 500. Thus, indicating that the EGR system is deteriorated at 532 can include setting a malfunction indicator light (MIL) at the vehicle dashboard, alerting the vehicle operator of a request to service the vehicle. Further, a flag can be set at the controller, indicating that the EGR cleaning procedure of the method 500 has been performed, but was unsuccessful in restoring the EGR flow to the expected EGR flow.

[0116] After determining that the EGR system is deteriorated, the method 500 can proceed to 522. Whether or not it is indicated that there is EGR system deterioration, or if it is indicated that carbon deposits are removed from the EGR valve and / or the EGR passage, steps 522-528 are performed in the same manner. For example, even if the EGR system is indicated to be deteriorated, the procedures of the method 500 can result in some carbon deposits being removed from the EGR valve and / or the EGR passage. Thus, at 524, the engine can be maintained at startup for a predetermined duration, with the EGR valve closed and the second DEF injection valve closed. At 528, updating the vehicle operating parameters in accordance with the indicated EGR system deterioration can include operating the engine in a manner that avoids using the EGR until it is indicated that the deterioration has been remedied. In some examples in which the vehicle includes a hybrid vehicle, the vehicle can be operated in a pure electric mode or a hybrid operating mode as frequently as possible to avoid using the engine and the EGR passage. Further, at 528, in response to the completion of the procedures, the method 500 can include hibernating the controller. The method 500 can then end.

[0117] Importantly, it can be appreciated that, Figure 5The EGR cleaning method of the present disclosure includes providing on-board and on-demand EGR passage / EGR valve cleaning methods.

[0118] While Figure 5 the method of the present disclosure depicts an EGR valve and / or EGR passage cleaning method that utilizes DEF injection into the intake manifold, there can be instances where injection into the intake manifold is not desired, or in some instances, the vehicle can not be equipped with a DEF injection line to the intake manifold. Accordingly, a different method can be used that can include injecting DEF into the exhaust system. Such a method will be discussed in detail in Figure 6 .

[0119] Accordingly, turning now to Figure 6 , a high-level example method 600 for conducting an EGR cleaning procedure is shown in which DEF is injected into the exhaust passage of the vehicle. More specifically, such a method can be conducted in response to a request to clean the EGR passage and / or EGR valve, and can include injecting DEF into the exhaust passage with the engine being reverse rotated without fueling with the EGR valve open to direct the DEF into the EGR passage. Subsequently, the engine can be started to combust air and fuel to transfer combustion heat to the EGR passage, which can vaporize the DEF, convert the water component to steam, which can result in the removal of carbon deposits associated with the EGR valve and / or EGR passage. In this way, the EGR passage can be effectively cleaned in an on-board and on-demand manner.

[0120] The method 600 will be described with reference to the system described herein and shown in Figures 1-3B , but it should be understood that similar methods can be applied to other systems without departing from the scope of the present disclosure. The method 600 can be performed by a controller, such as the controller 212 in Figures 2A-2B , and can be stored at the controller as executable instructions in a non-transitory memory. The instructions for performing the method 600 and the remainder of the methods included herein can be performed by the controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference to Figure 1 and Figures 2A-2B . In accordance with the methods described below, the controller can employ actuators of the 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 (e.g., 262), an EGR valve (e.g., 253), etc.

[0121] Method 600 begins at 602 and can include estimating and / or measuring current vehicle operating conditions. Operating conditions can be estimated, measured, and / or inferred, and can include one or more vehicle conditions, such as vehicle speed, vehicle location, etc.; various engine conditions, such as engine state, engine load, engine speed, A / F ratio, etc.; various fuel system conditions, such as fuel level, fuel type, fuel temperature, etc.; various evaporative emissions system conditions, such as fuel vapor canister load, fuel tank pressure, etc.; and various environmental conditions, such as ambient temperature, humidity, barometric pressure, etc.

[0122] Proceeding to 604, method 600 can include determining whether conditions are met to conduct an EGR clean diagnostic. Conditions met to conduct an EGR clean diagnostic can include an indication of low EGR flow rate monitored via a pressure sensor (e.g., 256) in the EGR passage (e.g., 250). For example, expected EGR flow rates in the absence of carbon deposits associated with the EGR valve and / or in the EGR passage can be stored at the controller in the form of a lookup table, including expected flow rates at various engine speeds and / or other operating conditions. Low EGR flow rate can include a certain EGR flow rate level that differs from an expected EGR flow rate for a particular engine operating condition by a threshold value, such as by more than 5% or by more than 10%. In another example, conditions met to conduct an EGR clean diagnostic can include an indication of a deteriorating EGR system, such as evidenced by an unstable idle or a stall condition in some examples.

[0123] Conditions met can additionally or alternatively include an on event in which low flow is indicated in the EGR passage, or in which an EGR system deterioration is indicated. Conditions met can also include an indication that a temperature of an oxidation catalyst (e.g., 226) is below a threshold temperature. In some examples, conditions met at 504 can additionally or alternatively include an indication that 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.) has expired since a previous EGR clean diagnostic. Conditions met at 504 can additionally or alternatively include an indication that an amount of DEF stored in a DEF tank (e.g., 241) is greater than a predetermined threshold (e.g., >10%, >20%, or >30% full).

[0124] If conditions are not indicated to be met to conduct an EGR clean diagnostic at 604, method 600 can proceed to 606. At 606, method 600 can include maintaining current vehicle operating parameters. For example, if the vehicle is operating with the engine running, such operation can be maintained. Alternatively, if the vehicle is operating in which the vehicle is propelled in whole or in part via electric power, such operating condition can be continued. Method 600 can then end.

[0125] Returning 604, in response to the condition indicating that the EGR cleanliness diagnosis is to be performed, the method 600 can proceed to 607. At 607, the method 600 can include commanding the opening of an EGR valve (e.g., 253). For example, the controller can send a signal to the EGR valve, actuating it open. Proceeding to 608, the method 600 can include causing the engine to rotate unfueled in a reverse direction. Specifically, the motor (e.g., 120) can be commanded via the controller to turn or rotate the engine unfueled in a reverse direction. In some examples, causing the engine to rotate unfueled can include causing the engine to rotate unfueled at a predetermined engine speed (engine RPM).

[0126] Proceeding to 610, the method 600 can include periodically operating a first DEF injection valve (e.g., 292). Periodically operating the first DEF injection valve can include periodically operating the first DEF injection valve to inject a predetermined amount of DEF into the exhaust port for a predetermined duration. Accordingly, proceeding to 612, the method 600 can include indicating whether the predetermined duration has expired. If the predetermined duration has not expired, the method 600 can return to 608 and can include continuing to cause the engine to rotate unfueled in a reverse direction and can also include continuing to periodically operate the first DEF injection valve. Alternatively, in response to the predetermined duration expiring at 612, the method 600 can proceed to 614.

[0127] It can be appreciated that by injecting DEF into the exhaust passage via the first DEF injection valve and causing the engine to rotate unfueled in reverse with the EGR valve open, the DEF can be drawn through the engine and into the EGR passage (e.g., 250).

[0128] At 614, in response to the predetermined duration expiring, the method 600 can include stopping the reverse rotating engine and starting the engine to combust air and fuel. For example, the motor can be deactivated and, in one example, the engine can be rotated to a standstill and then started to combust air and fuel. It can be appreciated that when the engine is started to combust air and fuel, the engine turns or rotates in a default or forward direction. Further, at 614, the method 600 can include stopping the periodic operation of the first DEF injection valve. Fuel (and spark, where applicable) can be controlled via the controller to control the engine speed to a desired speed. Further, although not explicitly shown, an exhaust tuning valve (e.g., 299) can be controlled to a position where heat from the engine is effectively directed to the EGR passage. For example, in some examples, the exhaust tuning valve can be controlled to a fully closed configuration or can be mostly closed (e.g., 20% open or less), etc., such that engine exhaust heat is directed to the EGR passage.

[0129] Accordingly, proceeding to 616, the method 600 can include maintaining the engine speed at the desired engine speed. For example, the engine speed can be maintained at the 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 to enable additional air to be drawn into the intake to control the engine speed to the desired engine speed. The desired engine speed can include an engine speed in which heat from the combustion engine is expected to vaporize DEF directed to the EGR passage.

[0130] Proceeding to 618, the method 600 can include indicating whether carbon deposits are indicated to be removed from the EGR valve and / or the EGR passage. Specifically, at 618, the method 600 can include monitoring the pressure in the EGR passage and indicating whether the EGR flow for a particular engine operating condition (e.g., the desired engine speed) is within a threshold (e.g., within 5%) of an expected EGR flow (e.g., without carbon deposits in the EGR passage and / or associated with the EGR valve). As described above, a lookup table stored at the controller can include the expected EGR flow as a function of engine operating condition, and accordingly, such a lookup table can be queried at 618 via the controller in order to indicate whether carbon deposits have been removed from the EGR valve / EGR passage.

[0131] At 618, if carbon deposits have been removed, indicating that the EGR flow is within the threshold of the expected EGR flow, the method 600 can proceed to 620. In other words, in response to an indication that carbon deposits have been removed, the method 600 can proceed to 620. At 620, the method 600 can include commanding the EGR valve to a closed position.

[0132] Proceeding to 622, the method 600 can include maintaining the engine startup at the desired speed for a predetermined duration. Specifically, the engine can be maintained in operation combusting air and fuel in order to force any removed carbon deposits out of the exhaust. As a result of commanding the EGR valve closed at step 620, the deposits can be directed to the exhaust rather than the EGR passage. At 622, the predetermined duration can include a duration in which any carbon deposits expected to be removed from the EGR passage and / or the EGR valve can be directed to exit the exhaust. In some examples, the predetermined duration at 622 can include 1 minute, 2 minutes, 3 minutes, 4 minutes, or 5 minutes.

[0133] Proceeding to 624, the method 600 can include stopping or deactivating the engine following an indication that the predetermined duration (622) has expired. For example, fuel (and spark, where applicable) provided to the engine cylinders can be stopped, and the engine can be allowed to coast to a stop. At 628, the method 600 can include updating the vehicle operating parameters. In particular, the vehicle operating parameters can be updated to reflect an indication that the EGR valve and EGR passage are now clean or free of carbon deposits. Further, at 628, updating the vehicle operating parameters can include setting a flag at the controller indicating that an EGR cleaning procedure was performed, and that the procedure successfully removed carbon deposits from the EGR valve and / or EGR passage. In some examples, in response to completion of the EGR cleaning procedure, the method 600 can include hibernating the controller. The method 600 can then end.

[0134] Returning to 618, in response to an indication that carbon deposits were not removed from the EGR valve and / or EGR passage, the method 600 can proceed to 630. At 630, the method 600 can include indicating whether a predetermined duration has expired. The predetermined duration at 630 can include a duration in which carbon deposits associated with the EGR valve and / or EGR passage, which can be the culprit behind the low EGR flow, can be expected to be removed via the EGR cleaning procedure of the method 600. Thus, if at 630 it is indicated that the predetermined duration has not expired, the method 600 can return to 614 and can include continuing to operate the engine at the desired rotational speed, with the engine combusting air and fuel until it is indicated that the carbon deposits have been removed or the predetermined duration has expired. Thus, at 630, in response to an indication that the predetermined duration has expired, the method 600 can proceed to 632. At 632, the method 600 can include indicating that the EGR system is deteriorating. For example, because the procedures of the method 600 were unable to restore flow in the EGR system to the expected flow, there can be an indication that there is some underlying cause of the low flow that cannot be remedied via the procedures of the method 600. Thus, indicating that the EGR system is deteriorating at 632 can include setting a malfunction indicator light (MIL) at the vehicle dashboard, alerting the vehicle operator of a request to service the vehicle. Further, a flag can be set at the controller, indicating that the EGR cleaning procedure of the method 600 was performed, but was unsuccessful in restoring EGR flow to the expected EGR flow.

[0135] After determining EGR system degradation, the method 600 can proceed to 620. Whether or not EGR system degradation is indicated to exist, or if carbon deposits are indicated to be removed from the EGR valve and / or EGR passage, steps 620-628 are performed in the same manner. For example, even if the EGR system is indicated to be degraded, the procedures of the method 600 can still result in some carbon deposits being removed from the EGR valve and / or EGR passage. Thus, at 624, the engine can be maintained 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 accordance with the indicated EGR system degradation can include operating the engine in a manner that avoids using the EGR until the degradation is indicated to have been remedied. In some examples in which the vehicle includes a hybrid vehicle, the vehicle can be operated in a pure electric mode or hybrid operating mode as frequently as possible to avoid using the engine and EGR passage. Further, at 628, in response to completion of the procedure, the method 600 can include hibernating the controller. The method 600 can then end.

[0136] Importantly, it can be appreciated that, Figure 6 The EGR cleaning method of

[0137] Now turning to Figure 7 FIG. 7 shows an example timeline 700 for conducting a process to remove carbon deposits from one or more cylinders of a vehicle engine. In particular, the example timeline 700 demonstrates how vehicle systems can be operated in accordance with the method 600 of FIG. 6. Figure 4The depicted method proceeds this procedure. Timeline 700 includes curve 705, which indicates whether conditions indicate that a cylinder cleaning operation is satisfied (yes) or not satisfied (no). Timeline 700 also includes curve 710, which indicates the state of the engine over time. The engine can be turned on or off over time. Timeline 700 also includes curve 715, which indicates whether fuel is injected into the engine cylinders over time. Fuel injection can be turned on or off over time. In the example timeline 700, it can be understood that fuel injection includes fuel injection to all engine cylinders. Timeline 700 also includes curve 720, which indicates whether the second DEF injection valve (e.g., 296) is turned on or off over time. It can be understood that if the second DEF injection valve is on, then DEF can be injected into the intake manifold, while when the second DEF injection valve is off, DEF can be prevented from being injected into the intake manifold. Timeline 700 also includes curve 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 (+) speed compared to the engine off state. Line 726 represents a threshold engine speed for performing a cylinder cleaning procedure, where the engine speed can be maintained above the threshold during the cylinder cleaning procedure. Timeline 700 also includes curve 730, which indicates the position of the intake throttle (e.g., 262) over time. The throttle can be fully open, fully closed, or somewhere in between. Timeline 700 also includes curve 735, which indicates the engine cylinder torque over time. The numbers 1, 3, 4, 2 represent each cylinder of a four cylinder engine, and the number sequence represents the firing order of the respective cylinders. Further, for clarity, the numbers representing the cylinder firing order are not repeated throughout curve 735, but it can be understood that the firing order includes 1, 3, 4, 2 over the duration of curve 735. The torque of each cylinder can be monitored over time by one or more engine torque sensors (e.g., 267). The engine torque can increase (+) or decrease (-) over time. Line 736 represents the expected cylinder torque, provided that there are no carbon deposits associated with a particular engine cylinder.

[0138] At time tO, the engine is in operation (curves 710 and 725), and combustion air and fuel (curve 715). The second DEF injection valve (e.g., 296) is closed. While not explicitly shown, it can be further understood that if included, the first DEF injection valve (e.g., 292) is also closed. For example, a power balance test indicates that one cylinder (cylinder 4 in the example) is underperforming (curve 735), where underperforming can be understood to mean that an expected amount of cylinder torque is not being produced. For example, if the cylinder is free of any carbon deposits, the expected amount of cylinder torque can include an expected torque level. However, at time tO, the conditions have not yet indicated that the conditions are met for performing a cylinder cleaning operation.

[0139] At time tl, the conditions are indicated to be met for performing a cylinder cleaning operation (curve 705). For example, the conditions indicated to be met at time tl can include an engine idle state. Other conditions for indicating whether the conditions are met at time tl for performing a cleaning operation have been discussed in detail at step 404 of method 400, and thus will not be repeated here for the sake of brevity. However, in the example timeline 700, it can be understood that the vehicle operator has entered an off state, with the engine remaining running for a cylinder cleaning operation. For example, a message can be communicated to the vehicle operator that a cylinder diagnosis is being performed. For example, such a message can be communicated to the vehicle operator via a human machine interface (HMI). It can be understood that the controller can maintain wake up for the program.

[0140] According to Figure 4 With the depicted method 400, where the conditions are indicated to be met for performing a cylinder cleaning operation, DEF is injected into the intake manifold via the second DEF injection valve (e.g., 296). In particular, the second DEF injection valve can be operated periodically such that a predetermined amount of DEF is injected into the intake manifold for a predetermined duration of time. While the DEF is injected into the intake manifold between times tl and t2, the engine RPM is maintained above the threshold engine speed (represented by line 726). However, at time t2, the engine speed drops below the threshold engine speed. Accordingly, between times t2 and t3, the throttle (e.g., 262) is controlled to a more open position, resulting in the engine speed increasing to the threshold speed at time t4.

[0141] Between times t3 and t4, the engine speed is maintained above the threshold engine speed, and the DEF continues to be injected into the intake manifold. Further, between times t3 and t4, the cylinder torque for the underperforming engine cylinder (cylinder 4 in the example) returns to producing the expected amount of torque (represented by line 736).

[0142] In the event that the underperforming engine cylinder recovers to produce the expected torque, at time t4, the indication is that the cylinder cleaning procedure successfully removed the carbon deposits from the underperforming cylinder. Accordingly, the second DEF injection valve closes (curve 720). However, the engine maintains cranking between times t4 and t5 to evaporate any remaining amount of DEF injected into the intake manifold and / or within the engine cylinder.

[0143] At time t5, the engine is deactivated (curve 710) and fuel injection to the engine cylinder is discontinued (curve 715). Accordingly, the conditions no longer indicate that the cylinder cleaning diagnostic procedure (curve 705) is warranted. Between times t5 and t6, the engine is spun down to rest. While not explicitly shown, in response to completion of the cylinder cleaning diagnostic, the controller can enter a hibernation state.

[0144] While the example timeline described a case in which the conditions for conducting the cylinder cleaning diagnostic include an off state, in which the controller remains awake to conduct the procedure while the engine is operating, the procedure can be conducted in other operating conditions. For example, such a procedure can be conducted in an engine idling condition, in which the vehicle is stopped for a sufficient duration to conduct the procedure. For example, if the vehicle is stopped at a traffic light for an idling stop, the procedure can be conducted in some instances.

[0145] Turning now to Figure 8 , an example timeline 800 is shown for conducting an EGR system cleaning operation or EGR system cleaning procedure. More specifically, the example timeline 800 illustrates how the vehicle system proceeds according to Figure 5The depicted method proceeds with such a procedure. Timeline 800 includes curve 805, which indicates whether a condition is met (YES) or not met (NO) to proceed with an EGR system cleaning procedure as a function of time. Timeline 800 also includes curve 810, which indicates an engine state as a function of time. The engine can be on and turning or rotating in a forward or default direction, or the engine can be off. Timeline 800 also includes curve 815, which indicates whether fuel injection is provided to engine cylinders as a function of time. Shown for curve 815 are the numbers 1, 3, 4, 2, which represent the various engine cylinders, and where the sequence of numbers indicates the firing order of the various cylinders. Although only two sequences or numbers are indicated for clarity, it is understood that the firing order repeats in accordance with the indicated firing order. Timeline 800 also includes curve 820, which indicates whether a second DEF injection valve (e.g., 296) is open or closed as a function of time. It is understood that when the second DEF injection valve is open, DEF is injected into the intake manifold. Timeline 800 also includes curve 825, which indicates engine speed (e.g., engine RPM) as a function of time. Line 826 represents a threshold engine speed, where if the engine speed falls 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 be increased (+) compared to stopped. Timeline 800 also includes curve 830, which indicates the position of an intake throttle (e.g., 262) as a function of time. The throttle can be fully open (open), fully closed (closed), or somewhere between fully open and fully closed. Timeline 800 also includes curve 835, which indicates whether an EGR valve (e.g., 253) is open or closed as a function of time. Timeline 800 also includes curve 840, which indicates EGR flow as a function of time. The EGR flow can be measured, for example, via one or more pressure sensors (e.g., 256). Line 841 represents an expected EGR flow, where the expected EGR flow includes the EGR flow expected in the absence of carbon deposits in the EGR passage and / or EGR valve. The EGR flow can include no flow (0), the expected flow, or can be between the expected flow and no flow.

[0146] At time to, the engine is in operation (curve 810), and combustion air and fuel (curve 815) is being combusted. The second DEF injection valve is closed (curve 820), and the EGR valve is closed (curve 835). Thus, with the EGR valve closed, there is no flow in the EGR system (curve 840). The condition has not yet been met for proceeding with an EGR cleaning procedure (curve 805). However, although not explicitly shown, it is understood that the controller has identified the low flow condition in the EGR system, and has scheduled the EGR cleaning procedure to proceed in response to the condition being met.

[0147] Thus, at time ti, the conditions indicate that the EGR cleaning procedure is to be performed. For example, in the example timeline 800, it can be appreciated that a shut down event has occurred. Thus, where the conditions are met for performing the EGR cleaning procedure, the controller maintains wake up at time ti, and the engine is maintained spinning unfueled, e.g., via the motor, when fuel injection to the engine cylinders is stopped (curve 815). Further, at time ti, where the conditions are met for performing diagnostics, the EGR valve (e.g., 253) can be commanded to an open position. For example, the EGR valve can be commanded to a fully open position.

[0148] In response to the conditions being met for performing the EGR cleaning procedure, the second DEF injection valve is periodically actuated (curve 820) between times ti and t2 to inject a predetermined amount of DEF into the intake manifold for a predetermined duration. After the predetermined duration expires at time t2, fuel injection (and spark, where applicable) is provided to the plurality of engine cylinders, but one of the engine cylinders is not provided fuel injection (or spark, where applicable). In other words, all but one of the engine cylinders can be fired to combust air and fuel (curve 815), with the one engine cylinder not combusting air and fuel. In the example timeline 800, cylinder 3 is shown as deactivated or not receiving fuel injection (or spark, where applicable).

[0149] With all but one of the engine cylinders combusting air and fuel, DEF injection into the intake manifold can continue (curve 820) between times t2 and t3. With DEF continuing to be injected into the intake manifold and with one cylinder deactivated, the deactivated cylinder can include a route similar to that discussed above when all cylinders are deactivated but with the engine spinning unfueled.

[0150] With the engine combusting air and fuel (except for one cylinder), the heat from the combustion of the engine can cause the DEF to vaporize, which can cause the water component of the DEF to transition to a vapor, thereby cleaning carbon deposits associated with the EGR valve and / or the EGR passage. Thus, between times t2 and t3, the flow in the EGR passage is monitored as to whether the EGR flow is still lower than expected or whether the EGR flow becomes substantially equal to the expected EGR flow (e.g., within 5%).

[0151] At time t3, the EGR flow is indicated to include the expected flow. Accordingly, the injection of DEF into the intake manifold is stopped (curve 820). Fuel injection to the engine cylinders is maintained (curve 815) except for the case where all cylinders are fueled. In other words, all engine cylinders are combusting air and fuel. At time t4, the EGR valve is closed, so between times t4 and t5, the EGR flow is reduced to no flow. The engine is maintained running to combust air and fuel between times t4 and t5, which can push any carbon deposits that have been removed from the EGR passage away from the exhaust port. At time t5, the conditions no longer indicate that the EGR system cleaning diagnosis (curve 805) is satisfied. Accordingly, at time t5, the engine is shut off (curve 810), and fuel injection to the engine cylinders is stopped (curve 815). Accordingly, after time t5, the engine is rotated to rest (curve 825). Although not explicitly shown, after the test diagnosis is completed, the controller can enter a sleep state.

[0152] Turning now to Figure 9 FIG. 9 shows another example timeline 900 for conducting an EGR system cleaning operation or EGR system cleaning procedure. More specifically, the example timeline 900 illustrates how a vehicle system conducts such a procedure according to the method depicted in Figure 6 FIG. 8. The timeline 900 includes a curve 905 that indicates whether the conditions for conducting the EGR system cleaning procedure according to the method depicted in Figure 6The depicted method 600 EGR clean procedure. Timeline 900 also includes a curve 910 that indicates engine state as a function of time. The engine can be off or can be rotating in a forward (FWD) or reverse (REV) direction. Timeline 900 also includes a curve 915 that indicates whether fuel injection to the engine cylinders is on or off as a function of time. Timeline 900 also includes a curve 920 that indicates whether the first DEF injection valve (e.g., 292) is on or off as a function of time. It can be appreciated that when the first DEF injection valve is "on," DEF is injected into the exhaust passage. Timeline 900 also includes a curve 925 that indicates engine speed (e.g., engine RPM) as a function of time. Line 926 represents a threshold engine speed below which the engine can be controlled back to a desired engine speed if the engine speed drops during a particular portion of the test (e.g., when the engine is started to burn air and fuel). Timeline 900 also includes a curve 930 that indicates intake throttle (e.g., 262) position as a function of time. The throttle can be fully closed (CLOSED), fully open (OPEN), or somewhere in between. Timeline 900 also includes a curve 935 that indicates EGR valve (e.g., 253) state as a function of time. The EGR valve can be open or closed as a function of time. Timeline 900 also includes a curve 940 that indicates EGR flow in the EGR system as a function of time. For a particular vehicle operating condition, the EGR flow can be at an expected EGR flow, can be at no flow (0), or can be somewhere in between. Line 941 represents the expected EGR flow for a particular operating condition.

[0153] At time to, the engine is off (curve 910). Although not explicitly shown, it can be appreciated that the engine has been off for a duration of time such that the oxidation catalyst (e.g., 226) temperature is below a threshold temperature. The threshold temperature can include a temperature at which DEF can be directed through the catalyst without causing the DEF to vaporize. At time to, the conditions have not indicated that the EGR clean diagnostic (curve 905) is satisfied. With the engine off, fuel injection to the engine cylinders is also off (curve 915). Furthermore, since the conditions have not indicated that the EGR clean procedure is satisfied, the first DEF injection valve is off (curve 920). With the engine off, the engine RPM is 0 (curve 925), and the position of the throttle includes the closed throttle position (curve 930). Still further, the EGR valve is off (curve 935), and there is no EGR flow at time to (curve 940).

[0154] At time tl, conditions indicate that the EGR cleaning procedure (curve 905) is to be performed. For example, it can be appreciated that at time tl, an on event has occurred in which the EGR cleaning procedure is scheduled for the next available opportunity in which conditions indicate that the procedure is to be performed. In other words, it can be appreciated that the oxidation catalyst is below the threshold temperature at time tl.

[0155] In the event that conditions indicate that the EGR cleaning procedure is to be performed at time tl, the EGR valve (e.g., 253) is commanded to open at time tl. In the event that the EGR valve is commanded to open, the engine is rotated in a reverse orientation by, for example, the motor (e.g., 120) between times tl and t2. Further, the first DEF injection valve is periodically operated between times tl and t2 to inject DEF into the exhaust passage. The duty cycle can include a duty cycle by which a predetermined amount of DEF is injected into the exhaust passage for a predetermined duration. The engine speed is controlled to a predetermined or desired engine speed (curve 925) between times tl and t2. By having the engine rotate in a reverse orientation without fuel, in which DEF is injected into the exhaust passage, it can be appreciated that, due to the open EGR valve, DEF can be directed to the EGR passage via the engine. This directing of DEF to the EGR passage can be for a predetermined duration.

[0156] At time t2, the predetermined duration expires. Accordingly, the first DEF injection valve is closed and the engine ceases to rotate in a reverse orientation. In other words, the motor can be deactivated and the engine can be rotated to rest between times t2 and t3 (curve 925). After the engine is rotated to rest, the engine can be started at time t3 in a mode in which the engine combusts air and fuel. Specifically, the engine can be started to rotate in a forward direction (curve 910) in which each engine cylinder (1, 3, 4, 2) is provided with fueling (curve 915) (and a spark, if applicable). By operating the engine to combust air and fuel, it can be appreciated that heat from the combustion can be directed to the EGR passage (while the EGR valve remains open) to vaporize the DEF directed to the EGR passage. Accordingly, between times t3 and t4, the engine is controlled to a speed above a threshold speed (represented by line 926). The threshold speed can include a speed at which engine stalling can be avoided or prevented when performing the procedure. Further, between times t3 and t4, the EGR flow is monitored, for example, via the pressure sensor (e.g., 256).

[0157] At time t4, the flow in the EGR system reaches an expected EGR flow, in which the expected EGR flow includes an expected flow for a given operating condition in the absence of carbon deposits associated with the EGR valve and / or the EGR passage.

[0158] When the EGR flow returns to the expected flow at time t4, the EGR valve closes (curve 935), and thus between times t4 and t5, the EGR flow in the EGR passage drops to no flow. However, the engine maintains cranking to combust air and fuel between times t4 and t5. The engine maintains cranking such that any carbon deposits that have been removed from the EGR passage and / or EGR valve can be forced out of the exhaust passage when the EGR valve is closed. After an indication that the EGR passage and / or EGR valve has been cleaned, the engine can maintain cranking for a predetermined duration. Thus, at time t5, the predetermined duration expires, and thus, the conditions no longer indicate that the EGR cleaning procedure (curve 905) is to be performed. Further, in the example timeline, it can be appreciated that the on event at time ti is to start the vehicle for a drive to another destination. Thus, while fuel injection is stopped at time t5, it can be appreciated that the engine is maintained in rotation in the forward direction via the motor to enable the vehicle to start in the electrically operated mode. Thus, between times t5 and t6, the engine is maintained to rotate un-fueled in the forward direction.

[0159] In this way, vehicle engine cylinders can be cleaned on-board and on-demand. By periodically cleaning the engine cylinders, carbon deposits can be periodically removed from the engine cylinders. These actions can improve engine performance and increase fuel economy. Still further, undesirable emissions can be reduced.

[0160] A technical effect is the recognition that for vehicles that include a DEF injection system, such a system can be utilized to direct DEF into the intake manifold of the engine such that the DEF can be drawn into the engine as the engine is combusted. By drawing the DEF into the combustion engine, the water component of the DEF can evaporate, whereby the steam can be used to effectively clean the engine and associated components of carbon deposits. A further technical effect is the recognition that to direct the DEF to the intake manifold, a DEF line can be introduced to specifically direct the DEF to the intake manifold under predetermined operating conditions. In this way, a DEF injection system that is present in a diesel vehicle can be utilized to perform an engine cylinder cleaning operation. By utilizing a DEF injection system that is already present in a diesel vehicle, the costs associated with a cylinder cleaning operation can be significantly reduced. Further, such a procedure can result in a reduction in the time spent servicing the vehicle, which can reduce the costs associated with servicing the vehicle, which can result in increased customer satisfaction.

[0161] The system described herein and with reference to Figures 1-3B and the system described herein and with reference to Figures 4-6Methods of the present disclosure can implement one or more systems and one or more methods. In one example, a method includes, in response to an indication of degradation in one or more cylinders of a vehicle engine, reducing carbon buildup associated with the one or more cylinders by injecting diesel exhaust fluid into an intake manifold of the engine and drawing the diesel exhaust fluid into the engine as the engine combusts air and fuel. In a first example of the method, the method further includes wherein the diesel exhaust fluid is stored in a tank located in a diesel exhaust fluid system, and wherein a first diesel exhaust fluid line is configured to selectively direct the diesel exhaust fluid to an exhaust passage, and wherein a second diesel exhaust fluid line is configured to selectively direct the diesel exhaust fluid to the intake manifold. A second example of the method optionally includes the first example, and further includes: adjusting an air-to-fuel ratio at the time of the injection of the diesel exhaust fluid into the intake manifold as the engine combusts air and fuel. A third example of the method optionally includes any one or more or each of the first example and the second example, and further includes: wherein adjusting the air-to-fuel ratio includes controlling the air-to-fuel ratio to a rich air-to-fuel ratio. A fourth example of the method optionally includes any one or more or each of the first example through the third example, and further includes: wherein the diesel exhaust fluid includes a water component and a urea component. A fifth example of the method optionally includes any one or more or each of the first example through the fourth example, and further includes: wherein injecting the diesel exhaust fluid into the intake manifold and drawing the diesel exhaust fluid into the engine as the engine combusts air and fuel causes the water component of the diesel exhaust fluid to evaporate into a vapor in order to reduce the carbon buildup. A sixth example of the method optionally includes any one or more or each of the first example through the fifth example, and further includes: wherein the indication of degradation further includes an indication that a torque measured in the one or more cylinders of the engine is lower than an expected or desired torque, and / or an indication that a pressure in the one or more cylinders of the engine is lower than an expected or desired pressure. A seventh example of the method optionally includes any one or more or each of the first example through the sixth example, and further includes: injecting the diesel exhaust fluid into the intake manifold during an engine idle state. An eighth example of the method optionally includes any one or more or each of the first example through the seventh example, and further includes: injecting the diesel exhaust fluid into the intake manifold in response to a shutdown event, wherein a controller of the vehicle is maintained in an awake state to reduce the carbon buildup, and wherein the controller enters a sleep state after reducing the carbon buildup.A ninth example of the method optionally includes any one or more or each of the first through eighth examples, and further includes: wherein an amount of the diesel exhaust fluid injected into the intake manifold during a time period including the injection of the diesel exhaust fluid is a threshold amount less than an amount of fuel provided to the engine. A tenth example of the method optionally includes any one or more or each of the first through ninth examples, and further includes: controlling an engine speed to a desired engine speed during the injection of the diesel exhaust fluid into the intake manifold.

[0162] A further example of a method includes, in a first operating condition of a vehicle, including an indication of degradation of one or more cylinders of an engine and no indicated degradation in an exhaust gas recirculation system, injecting a diesel exhaust fluid into an intake manifold of the engine with an exhaust gas recirculation valve closed to mitigate the degradation of the one or more cylinders; and in a second operating condition of the vehicle, including an indication of degradation in the exhaust gas recirculation system and no degradation in the one or more cylinders and / or an indication of the degradation in the one or more cylinders of the engine, injecting the diesel exhaust fluid into the intake manifold of the engine with the exhaust gas recirculation valve open to mitigate the degradation of the exhaust gas recirculation system. In the first example of the method, the method further includes: wherein the indication of the degradation of one or more cylinders includes an indication of a torque measured in the one or more cylinders of the engine that is lower than an expected or desired torque and / or an indication of a pressure in the one or more cylinders of the engine that is lower than an expected or desired pressure. A second example of the method optionally includes the first example and further includes: injecting the diesel exhaust fluid into the intake manifold while the engine is combusting air and fuel during the first operating condition; and ceasing injecting the diesel exhaust fluid into the intake manifold in response to an indication that the degradation of the one or more engine cylinders has been mitigated, wherein mitigating the degradation of the one or more engine cylinders includes reducing or removing carbon buildup associated with the one or more engine cylinders. A third example of the method optionally includes any one or more or each of the first example and the second example and further includes: injecting the diesel exhaust fluid into the intake manifold while the engine is rotating un-fueled in a forward direction during the second operating condition, wherein injecting the diesel exhaust fluid and rotating the engine un-fueled is continued for a first predetermined duration; and in response to expiration of the first predetermined duration, starting the engine to combust air and fuel without fuel being received by one engine cylinder; maintaining injecting the diesel exhaust fluid into the intake manifold and maintaining the exhaust gas recirculation valve open while the engine is combusting air and fuel, and ceasing injecting the diesel exhaust fluid and closing the exhaust gas recirculation valve in response to an indication that the degradation of the exhaust gas recirculation system has been mitigated, wherein mitigating the degradation of the exhaust gas recirculation system includes reducing or removing carbon buildup in an exhaust gas recirculation passage of the exhaust gas recirculation system and / or reducing or removing carbon buildup associated with the exhaust gas recirculation valve.A fourth example of the method optionally includes any one or more or each of the first through third examples, and further includes: wherein the one engine cylinder that does not receive fuel does not include the one or more cylinders of the engine having the indication of deterioration at the second condition. A fifth example of the method optionally includes any one or more or each of the first through fourth examples, and further includes: wherein the indication of deterioration in the exhaust gas recirculation system is responsive to a flow in the exhaust gas recirculation system being lower than a desired flow at a predetermined vehicle operating condition when the exhaust gas recirculation valve is open, and / or responsive to the flow in the exhaust gas recirculation system being higher than the desired flow with the exhaust gas recirculation valve closed.

[0163] A system for a vehicle includes an engine system including an engine having a plurality of engine cylinders, an intake manifold of the engine, and an exhaust passage of the engine; a diesel exhaust fluid (DEF) injection system including a first DEF delivery line selectively fluidly coupled to the exhaust passage via a first DEF injection valve, and including a second DEF delivery line selectively fluidly coupled to the intake manifold via a second DEF injection valve; one or more torque sensors configured to provide an indication of torque of the plurality of engine cylinders; and a controller storing instructions in non-transitory memory that, when executed, cause the controller to monitor the torque of the plurality of engine cylinders; indicate, from the torque as monitored via the one or more torque sensors, that carbon accumulation exists on one or more of the plurality of engine cylinders; and in response to the carbon accumulation being indicated to exist on the one or more of the plurality of engine cylinders, cause the second DEF injection valve to be periodically operated while maintaining the first DEF injection valve closed, and operate the engine to combust air and fuel during the causing of the second DEF injection valve to be periodically operated so as to remove the carbon accumulation. In a first instance of the system, the system further includes an exhaust gas recirculation system including an exhaust gas recirculation passage, an exhaust gas recirculation valve, and a pressure sensor located in the exhaust gas recirculation passage; and wherein the controller includes further instructions to indicate, from a flow in the exhaust gas recirculation system as monitored via the pressure sensor located in the exhaust gas recirculation passage under predetermined conditions, whether degradation exists in the exhaust gas recirculation system; and cause the second DEF injection valve to be periodically operated, and operate the engine to combust air and fuel with the exhaust gas recirculation valve closed during the causing of the second DEF injection valve to be periodically operated in conditions where degradation of the exhaust gas recirculation system is not indicated to exist but where the carbon accumulation is indicated to exist on the one or more of the plurality of engine cylinders.A second instance of the system optionally includes the first instance and further includes a motor configured to rotate the engine unfueled, and wherein the controller stores further instructions to, in response to the indication of the degradation in the exhaust gas recirculation system and further in response to the indication of the carbon accumulation on the one or more of the plurality of engine cylinders prior to periodically actuating the second DEF injection valve and operating the engine to combust air and fuel; periodically actuate the second DEF injection valve with the exhaust gas recirculation valve open while operating the motor to rotate the engine unfueled for a first predetermined duration; and after expiration of the first predetermined duration, start the engine to combust air and fuel with one cylinder of the engine unfueled while continuing to periodically actuate the second DEF injection valve for a second predetermined duration or until it indicates that one or more of the carbon accumulations are present on the one or more engine cylinders and / or alleviates the degradation of the exhaust gas recirculation system, wherein the one cylinder of the engine unfueled includes a cylinder for which the presence of a carbon accumulation is not indicated. It is noted that the example controls and estimation procedures included herein can be used with various engine and / or vehicle system configurations. The control methods and procedures disclosed herein can be stored as executable instructions in non-transitory memory and can be executed by a control system including a controller in conjunction with various sensors, actuators, and other engine hardware. The particular procedures described herein can represent one or more of any number of processing strategies such as event-driven, interrupt-driven, multi-task, multi-thread, and so on. As such, the various acts, operations, and / or functions illustrated can be performed in the manner shown, concurrently, in parallel, or in some cases omitted. Likewise, the order of processing is not necessarily restricted to that shown unless specifically stated. One or more of the acts, operations and / or functions illustrated can be repeated or performed in other orders, as appropriate. Further, the described acts, operations and / or functions can graphically represent code to be programmed into non-transitory memory of a computer readable storage medium of an engine control system, where the described acts are performed by execution of instructions in the system including various engine hardware components in combination with an electronic controller.

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

[0165] The following claims particularly point out certain combinations and subcombinations that are regarded as novel and nonobvious. These claims can refer to "a" or "an" element or to "first" or "second" elements or the equivalent thereof. Such claims have the same scope as if each term thereof was individually recited in the patent claims. Other combinations and subcombinations than those specifically recited can be claimed by amending the following claims to accordingly. Such amending is to be regarded as permitted under 35 U.S.C. 122 and 132.

[0166] According to the present invention, there is provided a method of reducing carbon build-up associated with one or more cylinders of a vehicle engine in response to an indication of degradation in the one or more cylinders of the engine by injecting diesel exhaust fluid into an intake manifold of the engine and drawing the diesel exhaust fluid into the engine as the engine combusts air and fuel.

[0167] According to one embodiment, the above invention features further comprise storing the diesel exhaust fluid in a tank located in a diesel exhaust fluid system, and wherein a first diesel exhaust fluid line is configured to selectively direct the diesel exhaust fluid to an exhaust passage, and wherein a second diesel exhaust fluid line is configured to selectively direct the diesel exhaust fluid to the intake manifold.

[0168] According to one embodiment, the above invention features further comprise adjusting an air-to-fuel ratio at the time the diesel exhaust fluid is injected into the intake manifold as the engine combusts air and fuel.

[0169] According to one embodiment, adjusting the air-to-fuel ratio comprises controlling the air-to-fuel ratio to a rich air-to-fuel ratio.

[0170] According to one embodiment, the diesel exhaust fluid comprises a water component and a urea component.

[0171] According to one embodiment, injecting the diesel exhaust fluid into the intake manifold and drawing the diesel exhaust fluid into the engine as the engine combusts air and fuel causes the water component of the diesel exhaust fluid to evaporate into a vapor so as to reduce the carbon build-up.

[0172] According to one embodiment, the indication of degradation further comprises an indication that a torque measured in the one or more cylinders of the engine is lower than an expected or desired torque, and / or an indication that a pressure in the one or more cylinders of the engine is lower than an expected or desired pressure.

[0173] According to one embodiment, the application features injecting the diesel exhaust fluid into the intake manifold during an engine idle condition.

[0174] According to one embodiment, the application features injecting the diesel exhaust fluid into the intake manifold in response to a shut down event, wherein a controller of the vehicle is maintained in an awake state to reduce the carbon accumulation, and wherein the controller enters a sleep state after reducing the carbon accumulation.

[0175] According to one embodiment, an amount of the diesel exhaust fluid injected into the intake manifold during a period of time including the injection of the diesel exhaust fluid is a threshold amount less than an amount of fuel provided to the engine.

[0176] According to one embodiment, the application features controlling an engine speed to a desired engine speed during the injection of the diesel exhaust fluid into the intake manifold.

[0177] According to the application, there is provided a method of injecting diesel exhaust fluid into an intake manifold of an engine in a first operating condition of a vehicle including a degradation of one or more cylinders of the engine and an absence of an indication of the degradation in an exhaust gas recirculation system to mitigate the degradation of the one or more cylinders with the exhaust gas recirculation valve closed; and in a second operating condition of the vehicle including a degradation in the exhaust gas recirculation system and an absence of an indication of the degradation in the one or more cylinders and / or an indication of the degradation in the one or more cylinders of the engine, injecting the diesel exhaust fluid into the intake manifold of the engine with the exhaust gas recirculation valve open to mitigate the degradation of the exhaust gas recirculation system.

[0178] According to one embodiment, the indication of the degradation of one or more cylinders includes an indication that a torque measured in the one or more cylinders of the engine is lower than an expected or desired torque, and / or an indication that a pressure in the one or more cylinders of the engine is lower than an expected or desired pressure.

[0179] According to one embodiment, the application features injecting the diesel exhaust fluid into the intake manifold during the first operating condition while the engine is combusting air and fuel; and ceasing the injection of the diesel exhaust fluid into the intake manifold in response to an indication that the degradation of the one or more engine cylinders has been mitigated, wherein mitigating the degradation of the one or more engine cylinders includes reducing or removing a carbon accumulation associated with the one or more engine cylinders.

[0180] According to one embodiment, the application further features injecting the diesel exhaust fluid into the intake manifold while the engine is un-fueled and rotating in the forward direction in the second operating condition, where injecting the diesel exhaust fluid and un-fueled rotating the engine is continued for a first predetermined duration; and in response to expiration of the first predetermined duration, starting the engine to combust air and fuel without fuel being received by one engine cylinder; maintaining injecting the diesel exhaust fluid into the intake manifold and maintaining the exhaust gas recirculation valve open while the engine combusts air and fuel, and in response to an indication that the degradation of the exhaust gas recirculation system has been mitigated, ceasing injecting the diesel exhaust fluid and closing the exhaust gas recirculation valve, where mitigating the degradation of the exhaust gas recirculation system includes reducing or removing carbon buildup in an exhaust gas recirculation passage of the exhaust gas recirculation system and / or reducing or removing carbon buildup associated with the exhaust gas recirculation valve.

[0181] According to one embodiment, the one engine cylinder that does not receive fuel does not include the one or more cylinders of the engine that have the indication of degradation in the second condition.

[0182] According to one embodiment, the indication of the degradation in the exhaust gas recirculation system is in response to a flow in the exhaust gas recirculation system being lower than a desired flow in a predetermined vehicle operating condition when the exhaust gas recirculation valve is open, and / or in response to the flow in the exhaust gas recirculation system being higher than the desired flow with the exhaust gas recirculation valve closed.

[0183] According to the present invention, there is provided a system for a vehicle, the system having: an engine system including an engine having a plurality of engine cylinders, an intake manifold of the engine, and an exhaust passage of the engine; a diesel exhaust fluid (DEF) injection system including a first DEF delivery line selectively fluidly coupled to the exhaust passage via a first DEF injection valve, and including a second DEF delivery line selectively fluidly coupled to the intake manifold via a second DEF injection valve; one or more torque sensors configured to provide an indication of torque of the plurality of engine cylinders; and a controller storing instructions in non-transitory memory that, when executed, cause the controller to: monitor the torque of the plurality of engine cylinders; indicate that carbon accumulation exists on one or more of the plurality of engine cylinders according to the torque as monitored via the one or more torque sensors; and in response to the carbon accumulation being indicated to exist on the one or more of the plurality of engine cylinders, cause the second DEF injection valve to be periodically operated while maintaining the first DEF injection valve closed, and operate the engine to combust air and fuel during the causing of the second DEF injection valve to be periodically operated in order to remove the carbon accumulation.

[0184] According to one embodiment, the above invention is further characterized by: an exhaust gas recirculation system including an exhaust gas recirculation passage, an exhaust gas recirculation valve, and a pressure sensor located in the exhaust gas recirculation passage; and wherein the controller includes further instructions to indicate whether degradation exists in the exhaust gas recirculation system according to flow in the exhaust gas recirculation system as monitored via the pressure sensor located in the exhaust gas recirculation passage under predetermined conditions; and in which conditions in which degradation of the exhaust gas recirculation system is not indicated to exist but in which the carbon accumulation is indicated to exist on the one or more of the plurality of engine cylinders, cause the second DEF injection valve to be periodically operated and operate the engine to combust air and fuel with the exhaust gas recirculation valve closed during the causing of the second DEF injection valve to be periodically operated.

[0185] According to one embodiment, the present application is further characterized by: a motor configured to rotate the engine unfueled, and wherein the controller stores further instructions to, in response to the indication of the degradation in the exhaust gas recirculation system and further in response to the indication of the carbon accumulation on the one or more of the plurality of engine cylinders, prior to periodically actuating the second DEF injection valve and operating the engine to combust air and fuel; periodically actuating the second DEF injection valve with the exhaust gas recirculation valve open while operating the motor to rotate the engine unfueled for a first predetermined duration; and after expiration of the first predetermined duration, starting the engine to combust air and fuel with one cylinder of the engine unfueled while continuing to periodically actuate the second DEF injection valve for a second predetermined duration or until it indicates that one or more of the carbon accumulation exists on the one or more engine cylinders and / or mitigates the degradation of the exhaust gas recirculation system, wherein the one cylinder of the engine unfueled includes a cylinder for which the existence of carbon accumulation is not indicated.

Claims

1. A method for cleaning an engine, comprising: in a first operating condition of a vehicle, including a degradation of one or more cylinders of an engine and an indication of no indicated degradation in an exhaust gas recirculation system, injecting a diesel exhaust fluid into an intake manifold of the engine with an exhaust gas recirculation valve closed to evaporate water of the diesel exhaust fluid using heat generated by engine combustion to mitigate the degradation of the one or more cylinders; and in a second operating condition of the vehicle, including a degradation in the exhaust gas recirculation system and an indication of no degradation in the one or more cylinders and / or an indication of the degradation in the one or more cylinders of the engine, injecting the diesel exhaust fluid into the intake manifold of the engine with the exhaust gas recirculation valve open and operating the engine to rotate in a forward direction un-fueled to direct the diesel exhaust fluid into the exhaust gas recirculation system to evaporate water of the diesel exhaust fluid using heat generated by engine combustion to mitigate the degradation of the exhaust gas recirculation system.

2. The method of claim 1, wherein the indication of the degradation of one or more cylinders includes an indication that a torque measured in the one or more cylinders of the engine is lower than an expected or desired torque and / or an indication that a pressure in the one or more cylinders of the engine is lower than an expected or desired pressure.

3. The method of claim 1, further comprising: during the first operating condition, injecting the diesel exhaust fluid into the intake manifold as the engine combusts air and fuel; and in response to an indication that the degradation of the one or more engine cylinders has been mitigated, ceasing to inject the diesel exhaust fluid into the intake manifold, wherein mitigating the degradation of the one or more engine cylinders includes reducing or removing carbon buildup associated with the one or more engine cylinders.

4. The method of claim 1, further comprising: while the engine is rotating in the forward direction un-fueled in the second operating condition, injecting the diesel exhaust fluid into the intake manifold, wherein injecting the diesel exhaust fluid and rotating the engine un-fueled is sustained for a first predetermined duration; and in response to expiration of the first predetermined duration, starting the engine to combust air and fuel without fuel being received by one engine cylinder; maintaining the diesel exhaust fluid injected into the intake manifold and the exhaust gas recirculation valve open while the engine combusts air and fuel, and in response to an indication that the degradation of the exhaust gas recirculation system has been mitigated, ceasing to inject the diesel exhaust fluid and closing the exhaust gas recirculation valve, wherein mitigating the degradation of the exhaust gas recirculation system includes reducing or removing carbon buildup in an exhaust gas recirculation passage of the exhaust gas recirculation system and / or reducing or removing carbon buildup associated with the exhaust gas recirculation valve.

5. The method of claim 4, wherein the one engine cylinder that does not receive fuel does not include the one or more cylinders of the engine having the indication of degradation in the second operating condition.

6. The method of claim 1, wherein the indication of degradation in the exhaust gas recirculation system is in response to a flow in the exhaust gas recirculation system being lower than an expected flow in a predetermined vehicle operating condition when the exhaust gas recirculation valve is open, and / or in response to the flow in the exhaust gas recirculation system being higher than the expected flow with the exhaust gas recirculation valve closed.

7. A system for a vehicle capable of cleaning an engine, the system comprising: an engine system including an engine having a plurality of engine cylinders, an intake manifold of the engine, and an exhaust passage of the engine; a diesel exhaust fluid (DEF) injection system including a first DEF delivery line selectively fluidly coupled to the exhaust passage via a first DEF injection valve, and including a second DEF delivery line selectively fluidly coupled to the intake manifold via a second DEF injection valve; one or more torque sensors configured to provide an indication of torque of the plurality of engine cylinders; an exhaust gas recirculation system including an exhaust gas recirculation passage, an exhaust gas recirculation valve, and a pressure sensor located in the exhaust gas recirculation passage; and a controller storing instructions in a non-transitory memory that, when executed, cause the controller to: monitor the torque of the plurality of engine cylinders; indicate, from the torque monitored via the one or more torque sensors, that carbon accumulation exists on one or more of the plurality of engine cylinders; indicate, from a flow in the exhaust gas recirculation system monitored via the pressure sensor located in the exhaust gas recirculation passage under predetermined conditions, whether degradation exists in the exhaust gas recirculation system; in response to the degradation of the exhaust gas recirculation system not being indicated but the carbon accumulation being indicated to exist on the one or more of the plurality of engine cylinders, periodically operate the second DEF injection valve and operate the engine to combust air and fuel with the exhaust gas recirculation valve closed during the periodically operating the second DEF injection valve in order to remove the carbon accumulation; and in response to the indication of degradation in the exhaust gas recirculation system and the indication that the carbon accumulation exists on the one or more of the plurality of engine cylinders and / or the indication that the carbon accumulation does not exist on the one or more of the plurality of engine cylinders, periodically operate the second DEF injection valve with the exhaust gas recirculation valve open and operate the engine to rotate unfueled in a forward direction to direct diesel exhaust fluid into the exhaust gas recirculation system to evaporate water of the diesel exhaust fluid with heat generated by engine combustion to mitigate the degradation of the exhaust gas recirculation system. ​ 8. The system of claim 7, further comprising: a motor configured to rotate the engine unfueled, and wherein the controller stores further instructions to, in response to the indication of the degradation in the exhaust gas recirculation system and further in response to the indication of the carbon accumulation on the one or more of the plurality of engine cylinders, periodically actuate the second DEF injection valve and operate the engine to combust air and fuel prior to the exhaust gas recirculation valve being open; periodically actuate the second DEF injection valve with the exhaust gas recirculation valve open while operating the motor to rotate the engine unfueled for a first predetermined duration; and after the first predetermined duration expires, start the engine to combust air and fuel with one cylinder of the engine unfueled while continuing to periodically actuate the second DEF injection valve for a second predetermined duration or until it indicates that one or more of the carbon accumulation exists on the one or more engine cylinders and / or mitigates the degradation of the exhaust gas recirculation system, wherein the one cylinder of the engine unfueled includes a cylinder for which carbon accumulation is not indicated to exist.

9. The system of claim 8, wherein periodically actuating the second DEF injection valve while maintaining the first DEF injection valve closed injects an amount of diesel exhaust fluid into the intake manifold that is a threshold amount less than an amount of fuel provided to the engine when operating the engine to combust air and fuel.

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