Method and system for removing moisture from an engine exhaust system

Abstract

The present disclosure provides "Methods and systems for removing moisture from an engine exhaust system". Methods and systems for removing moisture from an engine exhaust manifold are provided. In one example, a method includes operating an electric air compressor to remove moisture accumulated in the exhaust manifold in response to a higher than a threshold exhaust moisture content and a lower than a threshold engine run time during an immediately previous drive cycle during a vehicle key off condition.

Description

Technical Field

[0001] This instruction manual generally relates to methods and systems for removing moisture from engine exhaust systems. Background Technology

[0002] Condensation that accumulates in the engine exhaust during prolonged periods when the vehicle is ignited can lead to corrosion and rust in exhaust system components, such as the exhaust tailpipe. For example, moisture from humid air can condense on engine components, such as the exhaust manifold, and locally form puddles. During subsequent engine operation, these puddles can adversely affect the operation of exhaust system sensors.

[0003] Various methods have been provided to remove condensate from engine components. In one exemplary method shown in US 20140100074, Glugla et al. disclose a method for increasing airflow through a supercharged air cooler (CAC) to flush condensate from the CAC. During engine no-combustion conditions, the transmission system downshifts to a lower gear to increase engine speed and airflow via the CAC to flush stored condensate into the engine cylinders. By flushing condensate during engine no-combustion conditions, misfires due to water intake can be reduced.

[0004] However, the inventors of this paper have recognized the potential drawbacks of the aforementioned method. As an example, the method may not address condensation buildup on one or more engine components, such as the exhaust system. For instance, during periods when the engine is off (such as when the vehicle key is off, or during hybrid vehicle propulsion using motor torque from the system battery), moisture from the ambient air can condense and accumulate in the engine exhaust manifold. During driving cycles, exhaust temperatures may be insufficient to vaporize the moisture accumulated in the exhaust system due to engine start / stop conditions, deceleration fuel cut-off events, and periods of vehicle propulsion using motor torque. Moisture in the exhaust manifold can increase the time required for the exhaust oxygen sensor to function, thereby causing the engine to operate under open-loop control for longer periods and adversely affecting emission quality. Furthermore, freezing of water in the exhaust manifold and water splashing on the exhaust oxygen sensor can lead to inaccurate measurements by the sensor, which may adversely affect the determination of the required air-fuel ratio and engine dilution level for subsequent engine cycles. Summary of the Invention

[0005] The inventors have recognized herein that the aforementioned problem can be solved by an engine method comprising: in response to each of the following: the engine running time of a vehicle during a driving cycle being less than a threshold duration and the moisture content in the engine's exhaust or intake system being higher than a threshold level, activating an electric air compressor in the intake system to expel moisture from at least the exhaust system upon a key-off event following the driving cycle. In this way, when it may be impossible to remove moisture accumulated in the engine exhaust system during an engine cycle, the electric air compressor can be operated during an immediately following subsequent vehicle key-off state to allow compressed air to flow through the engine exhaust system to remove any accumulated moisture.

[0006] As an example, ambient humidity can be periodically monitored via an onboard vehicle humidity sensor or via a remote server during vehicle key deactivation events. An onboard camera can be used to monitor condensation formation on the vehicle's windshield. Upon vehicle key activation request, moisture formation in the engine exhaust system can be estimated based on ambient humidity conditions, local weather data, and an image of the windshield. If the amount of moisture in the exhaust system exceeds a threshold, the duration of engine operation can be estimated during a driving cycle by considering non-combustion conditions (including engine start / stop conditions, deceleration fuel cut-off events, and periods of vehicle propulsion using motor torque). Exhaust temperature can be monitored during the driving cycle. If the duration of engine operation is below a threshold, and / or if the exhaust temperature does not remain above the threshold temperature for a duration exceeding the threshold, it can be inferred that waste heat may be insufficient to vaporize the accumulated moisture. The engine may be a turbocharged engine comprising a turbine-driven intake compressor and an electrically driven intake compressor (also referred to herein as a battery-powered electric air compressor), the electrically driven intake compressor selectively operating to provide additional boost during periods of increased torque demand. During the subsequent period when the vehicle key is off, the intake throttle valve can be opened, the exhaust gas recirculation (EGR) valve can be opened, and the electric air compressor can be operated to allow compressed air to flow through the engine exhaust system. The increased flow of compressed air through the engine components allows accumulated moisture to be flushed out.

[0007] In this way, by selectively operating the electric air compressor, moisture accumulated in the engine exhaust system can be effectively removed. The advantage of operating the electric air compressor to remove moisture while the vehicle is ignited is that it dries the engine exhaust system using existing engine components, eliminating the need for additional components for condensate removal. By removing moisture from the exhaust manifold, the heating of the oxygen sensor can be accelerated, and closed-loop control of engine refueling can be initiated earlier, thereby improving fuel economy and emissions quality. Overall, by promptly flushing away water accumulated in the engine exhaust system, engine system components can be protected from degradation, and exhaust system sensors can operate optimally during subsequent engine cycles.

[0008] It should be understood that the foregoing description of the invention is intended to introduce, in a simplified form, the selection of concepts further described in the detailed description. This does not imply identification of key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that address any shortcomings mentioned above or in any part of this disclosure. Attached Figure Description

[0009] Figure 1 An exemplary engine system is shown, including an electric air compressor coupled to a hybrid vehicle.

[0010] Figure 2 A flowchart illustrating an exemplary method that can be implemented to estimate the moisture content accumulated in an engine exhaust system is shown.

[0011] Figure 3 A flowchart illustrating an exemplary method that can be implemented to remove moisture accumulated in an engine exhaust system is shown.

[0012] Figure 4 An exemplary operation of an electric air compressor for removing moisture from an engine exhaust system, according to the present disclosure, is shown. Detailed Implementation

[0013] The following description relates to systems and methods for removing moisture from engine components, such as engine exhaust systems. Reference is made to an exemplary engine system coupled to a hybrid vehicle system (e.g., Figure 1 As described in the diagram, an electric air compressor can be operated to remove moisture accumulated in engine components. The engine controller can be configured to execute control programs (such as...) Figure 2 An exemplary procedure is used to estimate the amount of moisture that has accumulated in the engine exhaust system. The controller can selectively operate the electric air compressor to, for example, during vehicle key-off events via... Figure 3The control program removes moisture from engine components. Figure 4 An exemplary operation of an electric air compressor capable of removing accumulated water is shown.

[0014] Figure 1 A schematic diagram 101 of a vehicle system 102 having an exemplary engine system 100 including an engine 10 is shown. In one example, engine system 100 may be a diesel engine system. In another example, engine system 100 may be a gasoline engine system. In the depicted embodiment, engine 10 is a turbocharged engine coupled to a turbocharger 15, which includes a compressor 114 driven by a turbine 116. Specifically, fresh air is introduced into engine 10 via an air purifier 112 along an intake duct 42 and flows to compressor 114. The compressor may be a suitable intake compressor, such as a motor-driven or drive shaft-driven supercharger compressor. In engine system 10, the compressor is a turbocharger compressor mechanically coupled to turbine 116 via a shaft 19, which is driven by the expansion of engine exhaust.

[0015] like Figure 1 As shown, compressor 114 is connected to throttle body 20 via supercharged air cooler (CAC) 118. Throttle body 20 is connected to engine intake manifold 22. Compressed air charges from the compressor, flows through supercharged air cooler 118 and throttle body 20 to intake manifold 22. Figure 1 In the embodiment shown, the manifold air pressure (MAP) sensor 124 senses the pressure of the air filling the intake manifold 22. The temperature of the ambient air entering the intake duct 42 can be estimated via the intake air temperature (IAT) sensor 51.

[0016] One or more sensors may be connected to the inlet of compressor 114. For example, temperature sensor 55 may be connected to the inlet to estimate compressor inlet temperature, while pressure sensor 56 may be connected to the inlet to estimate compressor inlet pressure. As another example, ambient humidity sensor 57 may be connected to the inlet to estimate the humidity of the air entering the intake manifold. Other sensors may include, for example, an air-fuel ratio sensor. In other examples, one or more of the compressor inlet conditions (such as humidity, temperature, pressure, etc.) may be inferred based on engine operating conditions. Furthermore, when exhaust gas recirculation (EGR) is enabled, the sensors may estimate the temperature, pressure, humidity, and air-fuel ratio of the air-fuel mixture comprising fresh air, recirculated compressed air, and residual exhaust gas received at the compressor inlet.

[0017] The wastegate actuator 91 can be actuated to open to depressurize at least some of the exhaust pressure from upstream of turbine 116 to downstream of turbine 116 via wastegate 90. By reducing the exhaust pressure upstream of the turbine, the turbine speed can be reduced, which in turn helps to reduce compressor surge.

[0018] To assist the turbocharger 15, an additional intake compressor (also referred to herein as an electric air compressor 155) can be integrated into the vehicle propulsion system. The electric air compressor 155 can be powered via an on-board energy storage device 250, which may include a battery, capacitor, supercapacitor, etc. The electric air compressor may include a compressor driven by an electric motor. The operating speed of the electric air compressor may include adjusting the operating speed of the electric motor, which is operated via the on-board energy storage device 250.

[0019] In one example, the electric air compressor 155 can be actuated in response to a demand for increased wheel torque, so as to rapidly supply the desired boost air to the engine while the turbocharged turbine engine accelerates. As a result, the increased torque can be met without causing turbo lag, which could otherwise occur if the assistance from the electric air compressor is unavailable. In such an example, the electric air compressor 155 can be actuated to shut down or deactivate in response to the turbocharger accelerating to a threshold speed (e.g., 70,000 rpm). More specifically, the operation of the air compressor 155 can be controlled based on command signals (e.g., duty cycle or pulse width signals) received from a vehicle controller (e.g., controller 12). For example, the controller can send a signal to the electric air compressor actuator 155b that actuates to turn on the electric air compressor. In one example, the electric air compressor actuator may include an electric motor that drives the air compressor.

[0020] An electric air compressor 155 can be positioned between a first electric air compressor conduit 159a and a second electric air compressor conduit 159b. The first electric air compressor conduit 159a fluidly connects the intake duct 42 upstream of the electric air compressor bypass valve 161 to the electric air compressor 155. The second electric air compressor conduit 159b fluidly connects the electric air compressor 155 downstream of the electric air compressor bypass valve 161 to the electric air compressor 155. As an example, air can be drawn into the electric air compressor 155 upstream of the electric air compressor bypass valve 161 via the first electric air compressor conduit 159a, and compressed air can exit the electric air compressor 155 and be guided via the second electric air compressor conduit to the intake duct 42 downstream of the electric air compressor bypass valve 161. In this way, compressed air can be directed to the engine intake port 22.

[0021] In a scenario where the electric air compressor 155 is activated to provide boost faster than when relying solely on the turbocharger 15, it is understood that the electric air compressor bypass valve 161 can be commanded to close when the electric air compressor 155 is activated. In this way, intake air can flow through the turbocharger 15 and through the electric air compressor 155. Once the turbocharger reaches its threshold speed, the electric air compressor 155 can be shut off, and the electric air compressor bypass valve 161 can be commanded to open.

[0022] Intake manifold 22 is connected to a series of combustion chambers 30 via a series of intake valves (not shown). The combustion chambers are also connected to exhaust manifold 36 via a series of exhaust valves (not shown). In the depicted embodiment, a single exhaust manifold 36 is shown. However, in other embodiments, the exhaust manifold may include multiple exhaust manifold sections. A configuration with multiple exhaust manifold sections allows effluent from different combustion chambers to be directed to different locations within the engine system.

[0023] In one embodiment, each of the exhaust valve and the intake valve may be electronically actuated or controlled. In another embodiment, each of the exhaust valve and the intake valve may be cam-actuated or controlled. Whether electronically actuated or cam-actuated, the opening and closing timing of the exhaust valve and the intake valve can be adjusted as needed to achieve desired combustion and emission control performance.

[0024] Combustion chamber 30 can be supplied with one or more fuels, such as gasoline, alcohol-fuel blends, diesel, biodiesel, compressed natural gas, etc., via injector 66. Fuel can be supplied to the combustion chamber via direct injection, port injection, throttle body injection, or any combination thereof. Combustion can be initiated in the combustion chamber via spark ignition and / or compression ignition.

[0025] like Figure 1 As shown, exhaust gas from one or more exhaust manifold sections can be directed to turbine 116 to drive the turbine. The combined flow from the turbine and exhaust valve then flows through emission control device 170. In one example, emission control device 170 may be an ignition catalyst. Typically, exhaust aftertreatment device 170 is configured to catalytically treat the exhaust stream, thereby reducing the amount of one or more substances in the exhaust stream. For example, exhaust aftertreatment device 170 may be configured to capture NO from the exhaust stream when the exhaust stream is lean. x Furthermore, when the exhaust flow is rich, the captured NO is reduced. x In other examples, the exhaust aftertreatment device 170 can be configured to cause NO to... x Disproportionation or selective reduction of NO using a reducing agent xIn other examples, exhaust aftertreatment device 170 may be configured to oxidize residual hydrocarbons and / or carbon monoxide in the exhaust stream. Different exhaust aftertreatment catalysts having any of this functionality may be arranged individually or together in the coating or elsewhere in the exhaust aftertreatment stage. In some embodiments, the exhaust aftertreatment stage may include a regenerable soot filter configured to capture and oxidize soot particles in the exhaust stream.

[0026] An exhaust gas recirculation (EGR) delivery passage 180 may be coupled upstream of the turbine 116 to the exhaust passage 104 to provide high-pressure EGR (HP-EGR) downstream of the compressor 114 to the engine intake manifold. An EGR valve 152 may be coupled to the EGR passage 180 at its junction with the intake passage 42. The EGR valve 152 may be opened to allow a controlled amount of exhaust gas to reach the compressor outlet to achieve desired combustion and emission control performance. The EGR valve 152 may be configured as a continuously variable valve or an on / off valve. In other embodiments, the engine system may include a low-pressure EGR (LP-EGR) flow path, wherein exhaust gas is drawn downstream of the turbine 116 and recirculated upstream of the compressor 114 to the engine intake manifold.

[0027] One or more sensors can be coupled to EGR channel 180 to provide details about the composition and condition of the EGR. For example, a temperature sensor can be provided to determine the temperature of the EGR, a pressure sensor can be provided to determine the pressure of the EGR, a humidity sensor can be provided to determine the humidity or water content of the EGR, and an air-fuel ratio sensor can be provided to estimate the air-fuel ratio of the EGR. Alternatively, the EGR condition can be inferred from one or more temperature, pressure, humidity, and air-fuel ratio sensors coupled to the compressor inlet.

[0028] Multiple sensors, including an exhaust temperature sensor 128, an exhaust oxygen sensor 129, an exhaust flow sensor, and an exhaust pressure sensor, can be connected to the main exhaust manifold 104. The oxygen sensor can be a linear oxygen sensor or a UEGO (universal or wide-range exhaust oxygen sensor), a dual-state oxygen sensor, or an EGO, HEGO (heated EGO), NOx, HC, or CO sensor.

[0029] During a vehicle key-off event following a driving cycle, the electric air compressor 155 may also operate in a timely manner in response to each of the engine operating time below a threshold during the driving cycle and the moisture content above a threshold in the exhaust manifold 36 to remove condensate accumulated in the exhaust manifold 36. The moisture content in the engine exhaust manifold 36 may be estimated based on the ambient humidity at the vehicle's location during the previous key-off event and further via an onboard camera 130 configured to determine the amount of moisture on the vehicle's windshield during the previous key-off event. In one example, the driving cycle may immediately precede the key-off event, and the previous key-off event may immediately precede the driving cycle. The engine operating time during the driving cycle may be a function of the number of start-stop events during the driving cycle, the duration of each start-stop event, the number of deceleration fuel cut-off (DFSO) events, and the duration of each DFSO event. Removing moisture from at least the exhaust system includes directing compressed air from the electric air compressor 155 through the intake and exhaust systems to remove moisture from each of the intake and exhaust systems to the atmosphere. To direct compressed air from the intake system to the exhaust system, each of the throttle valve 20, EGR valve 152, and wastegate valve 91 can be opened. Figure 2 and Figure 3 The details of the moisture removal method using the electric air compressor 155 are explained.

[0030] Engine system 100 may also include control system 14. Control system 14 is shown receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 18 (various examples of which are described herein). As an example, sensors 16 may include a MAP sensor 124, an exhaust temperature sensor 128, an exhaust oxygen sensor 129, a compressor inlet temperature sensor 55, a compressor inlet pressure sensor 56, an ambient humidity sensor 57, an IAT sensor 51, an engine coolant temperature sensor, and an EGR sensor. Other sensors (such as additional pressure, temperature, air-fuel ratio, and composition sensors) may be coupled to various locations within engine system 100. Furthermore, sensors coupled to the exterior of the vehicle system (such as a rain sensor (windshield sensor)) may be used to estimate ambient humidity. One or more cameras 130 may be coupled to the dashboard outside the vehicle and / or the passenger compartment to capture images of the road ahead of the vehicle. The cameras may also be used to capture images of the windshield.

[0031] Actuators 18 may include, for example, an electric air compressor bypass valve 161, a throttle valve 20, an electric air compressor actuator 155b, an EGR valve 152, a wastegate valve 92, and a fuel injector 66. Control system 14 may include a controller 12. Controller 12 may receive input data from various sensors, process the input data, and trigger various actuators in response to the processed input data based on instructions corresponding to one or more programs or codes programmed in the instructions. In one example, in response to a moisture content exceeding a threshold in exhaust manifold 36 during the vehicle key-off state (e.g., determined based on input from ambient humidity sensor 57 and onboard camera 130), controller 12 may signal the electric air compressor bypass valve 161 to actuate the valve to a closed position and signal the air compressor actuator 155b to actuate the electric air compressor 155 to cause compressed air to flow through each of intake manifold 22 and exhaust manifold 36 to remove accumulated condensate from each of intake manifold 22 and exhaust manifold 36.

[0032] Controller 12 can be coupled to wireless communication device 136 to enable vehicle 102 to communicate directly with network cloud 160. Using wireless communication 150 via device 136, vehicle 102 can retrieve data from network cloud 160 regarding current and / or upcoming environmental conditions (such as ambient humidity, temperature, pressure, etc.). Upon completion of a driving cycle, database 13 within controller 12 can be updated with guidance information including driver behavior data, engine status, date and time information, and traffic information. Furthermore, in some examples, the controller can communicate with a remote engine start receiver (or transceiver) that receives wireless signals from a key fob with a remote start button actuated by the vehicle driver from a location remote from the vehicle. In other examples (not shown), remote engine start can be initiated via a cellular phone or smartphone-based system, where the user's cellular phone sends data to a server, and the server communicates with the vehicle to start the engine.

[0033] In some examples, vehicle 102 may be a hybrid vehicle having multiple torque sources available for one or more wheels 157. In other examples, vehicle 102 may be a conventional vehicle with only an engine or an electric vehicle with only one or more electric motors. In the example shown, vehicle 102 includes an engine 10 and an electric motor 52. The electric motor 52 may be a motor or a motor / generator. When one or more clutches 156 are engaged, the crankshaft of engine 10 and electric motor 52 are connected to wheels 157 via transmission 46. In the depicted example, a first clutch 156 is disposed between the crankshaft and electric motor 52, while a second clutch 156 is disposed between electric motor 52 and transmission 46. Controller 12 may send signals to the actuator of each clutch 156 to engage or disengage the clutch, thereby connecting or disconnecting the crankshaft from electric motor 52 and its connected components, and / or connecting or disconnecting electric motor 52 from transmission 46 and its connected components. Transmission 46 may be a gearbox, planetary gear system, or other type of transmission. The powertrain may be configured in various ways, including parallel, series, or series-parallel hybrid vehicles.

[0034] The motor 52 receives power from the traction battery 58 to provide torque to the wheel 157. For example, during braking operations, the motor 52 can also be used as a generator to provide power to charge the traction battery 58.

[0035] In this way, Figure 1The components implement a system for a hybrid vehicle, the system comprising: a vehicle, including autonomous vehicles and / or hybrid vehicles; an electric motor coupled to a battery to propel the vehicle; an engine including one or more cylinders, an intake manifold, and an exhaust manifold; an intake duct including a compressor, a boost air cooler (CAC) downstream of the compressor, and an intake throttle valve downstream of the CAC; a duct connected to the intake duct downstream of the compressor and upstream of the CAC, the duct including a motor-driven electric compressor; an electric compressor bypass valve coupled to the junction of the intake duct and the duct; and one or more sensors including an ambient humidity sensor coupled to the intake manifold and an exhaust temperature sensor coupled to the exhaust manifold. The system includes: one or more cameras for capturing images of the windshield; an exhaust gas recirculation (EGR) passage downstream of the compressor connecting the exhaust manifold to the intake manifold, the EGR passage including an EGR valve; and a controller having computer-readable instructions stored in a non-transitory memory to perform the following operations: at the end of a driving cycle, estimating the moisture content in the exhaust manifold based on one or more images of the windshield, ambient humidity estimated via the ambient humidity sensor, the duration of engine operation, and changes in exhaust temperature during the driving cycle; and immediately afterward, during a subsequent vehicle key-off state, in response to a moisture content exceeding a threshold, operating the electric compressor to direct compressed air through the exhaust manifold to remove moisture from the exhaust manifold.

[0036] Figure 2 An exemplary method 200 is shown that can be implemented to estimate the moisture content accumulated in an engine exhaust system. This can be achieved by a controller based on instructions stored in the controller's memory and in conjunction with data from sensors in the engine system (such as those referenced above). Figure 1 The sensor described receives signals to execute instructions for performing method 200 and the remaining methods included herein. According to the methods described below, the controller can employ the engine actuators of the engine system to adjust engine operation.

[0037] At point 202, the procedure includes determining whether to request the vehicle key to be turned off. During the vehicle key-off state, the vehicle does not use engine torque and / or motor torque for propulsion, and the vehicle can remain stationary. During the vehicle key-off state, the transmission gear can be in the park position. In one example, the key can be turned off by the vehicle driver applying the brake pedal.

[0038] If it is determined that there is no request to turn off the vehicle key, then at point 204, the current vehicle operation can be maintained and the electric air compressor (such as...) can be operated as needed. Figure 1An electric air compressor 155 is used to provide boost assist during periods of increased torque demand. The electric air compressor can be coupled to a duct connected in parallel with the intake manifold, the duct being downstream of the intake compressor and upstream of the boost air cooler. This is achieved by operating a turbocharger (such as...) Figure 1 During periods when the boost pressure provided by the intake compressor 114 and exhaust turbine 116 is lower than the desired boost pressure, energy can be supplied from onboard energy storage devices (such as...) Figure 1 The energy stored in the energy storage device 250 is used to operate the electric air compressor to provide the desired boost. The operating speed and duration of the electric air compressor can be adjusted based on the turbocharger speed and the torque demand estimated via a pedal position sensor. In one example, the operating speed and duration of the electric air compressor can increase as the torque demand increases and the turbocharger speed decreases. In another example, the operating speed and duration of the electric air compressor can decrease as the torque demand decreases and the turbocharger speed increases.

[0039] If it is confirmed that the vehicle key has been requested to be turned off, then at point 206, immediately after the vehicle stops, it can be accessed via one or more onboard cameras (such as...). Figure 1 The camera 130 (from inside the vehicle) captures a first image of the windshield, and this first image can be stored in the controller's memory (database). Because the vehicle is already in motion, even if there is rain, the wipers will remove any moisture from the windshield. Therefore, the image captured immediately after the vehicle stops can show a clean windshield (without condensation).

[0040] At point 208, ambient humidity can be monitored at regular intervals throughout the entire duration of the vehicle's ignition-off state, and this humidity information can be stored in a database. This can be achieved via an intake humidity sensor (such as...). Figure 1 The system uses one or more of the humidity sensor 57 and the windshield humidity sensor to measure ambient humidity. In one example, ambient humidity can be measured at 30-minute intervals during the period when the vehicle is ignited. If the vehicle is parked overnight, there may be significant humidity changes (such as more than 10%) throughout the night. Along with the ambient humidity, the controller can also record the ambient temperature at regular intervals via the intake air temperature sensor throughout the vehicle's ignition-off state. Moisturized air can be trapped inside the engine intake manifold and engine cylinders when the engine is off. The amount of trapped air can be a function of the throttle opening. When the engine cools, water from the trapped air can condense on engine components.

[0041] At 210, it is possible to access external networks (such as...) Figure 1Retrieving local weather conditions, including ambient humidity and ambient temperature, from a network cloud (160) via wireless communication (such as... Figure 1 The wireless communication 150 is communicatively connected to the vehicle. The dew point temperature at the vehicle's current location can be obtained. If the ambient temperature is below the dew point temperature, ambient moisture may condense on engine components. Weather forecasts for the current location can also be obtained from external networks and stored in a database. The vehicle's current location can be obtained using GPS.

[0042] At 212, the procedure includes determining whether a vehicle key access request has been made. A key access request may include the driver using a key to initiate vehicle operation. For remote start, a vehicle key access signal may be received from a source outside the vehicle. In one example, the driver may remotely request engine start, enabling cabin heating to be initiated and the cabin reaching a desired temperature before the driver enters the cabin and begins driving the vehicle. In another example, such as when the vehicle has at least some autonomous functionality, in response to a request for remote vehicle start, a motor may operate to achieve the desired cabin temperature and then propel the vehicle using motor torque and / or engine torque. In yet another example, the driver of an autonomous vehicle may initiate vehicle operation (propulsion) from a remote location using wireless communication. The vehicle may be communicatively connected via wireless communication to an external source (such as a key fob, cellular phone, or smartphone) for remote engine start. Based on signals received from the remote source, the controller may schedule engine start at the requested time.

[0043] If it is determined that no vehicle key access request has been made, at point 213, the vehicle key can remain off and the current humidity level can be monitored. If it is determined that a vehicle key access request has been made, at point 214, a second image of the windshield can be captured via the onboard camera at the start of the driving cycle. During the period when the vehicle key is off, ambient moisture may condense on the windshield, forming a layer of water on its surface. In one example, when the vehicle key is accessed, the wipers can be activated to wipe the windshield once to remove any accumulated moisture. After wiping the windshield, a third image of the windshield can be captured via the onboard camera.

[0044] At point 216, the first moisture content in engine components, including the intake and exhaust manifolds, can be estimated based on each of the following: a windshield image, an estimate of ambient humidity over the entire duration of the vehicle's ignition off state, and local weather conditions during the ignition off state. The controller can retrieve ambient humidity and ambient temperature values ​​recorded throughout the vehicle's ignition off state, as well as local weather conditions including dew point temperatures stored in a database and obtained from an external network. In one example, the controller can estimate the first moisture content in the engine components based on each of the ambient humidity, ambient temperature, and dew point temperatures. In another example, the controller can use a lookup table to determine the first moisture content in the engine components, with the input being each of the ambient humidity, ambient temperature, and dew point temperatures, and the output being the moisture content in the engine components. In one example, the threshold is a non-zero threshold, where the threshold humidity corresponds to a humidity level above which moisture from the air is likely to condense and accumulate on the engine components. In another example, the threshold relative humidity level is 50%.

[0045] In one example, the controller can perform image analysis on each of the first, second, and third windshield images. If, during the vehicle's ignition-off state, the ambient temperature drops below the dew point and the ambient humidity increases above a threshold humidity, condensation may form on the windshield. During image analysis, the controller can subtract the first image from the second image to determine if a layer of moisture (appearing as a blur on the windshield) is present. If the third image shows that the windshield can be cleaned by operating the wipers, it can be inferred that the accumulation on the windshield is caused by moisture. The controller can use image analysis techniques to infer the amount of moisture accumulated on the windshield. The initial moisture content in engine components can be proportional to the amount of moisture accumulated on the windshield. If the third image shows that the windshield does not become clean after wiping, it can be inferred that substances other than moisture (such as dust, ash, etc.) have accumulated on the windshield.

[0046] In this way, at the start of a driving cycle, the first moisture content can be estimated based on one or more of the following: the amount of moisture accumulated on the vehicle's windshield during the immediate preceding vehicle key-off state, the change in ambient humidity during the immediate preceding vehicle key-off state, and the dew point temperature at the vehicle's location during the immediate preceding vehicle key-off state.

[0047] At 218, the procedure includes determining whether the moisture content accumulated on engine components, including the engine intake manifold and exhaust manifold, exceeds a first threshold moisture content. In one example, the first threshold moisture content can be a non-zero positive moisture content, above which the accumulated moisture can interfere with the operation of engine sensors such as the exhaust oxygen sensor. The controller can calibrate the first threshold moisture content based on the operation of one or more engine sensors. In one example, the threshold moisture content can be a relative humidity of 75%.

[0048] If it is determined that the moisture content accumulated on engine components, including the engine intake and exhaust manifolds, is below a threshold moisture content, it can be inferred that humidity is unlikely to have any adverse effect on engine components, including sensors, and / or on engine hardware. Therefore, at 220, it can be inferred that a moisture removal process is probably not desired.

[0049] If it is determined that the moisture content accumulated on engine components, including the engine intake and exhaust manifolds, exceeds a threshold moisture content, it may be desirable to remove the moisture if it does not vaporize during the driving cycle. At 220, engine operating time can be estimated based on each of the following: the number of start-stop (idle-stop) events during the driving cycle, the duration of each start-stop event, the number of deceleration fuel cut-off (DFSO) events, the duration of each DFSO event, and the duration of vehicle operation using motor torque during the driving cycle. Engine operating time can include the total amount of time the engine burns fuel and air. In one example, engine operating time can decrease as each of the following increases: the number of start-stop events during the driving cycle, the duration of each start-stop event, the number of DFSO events, the duration of each DFSO event, and the duration of vehicle operation using motor torque during the driving cycle. In another example, engine operating time can increase as each of the following decreases: the number of start-stop events during the driving cycle, the duration of each start-stop event, the number of DFSO events, the duration of each DFSO event, and the duration of vehicle operation using motor torque during the driving cycle.

[0050] At 224, it can be detected via an exhaust temperature sensor (such as...) during the driving cycle. Figure 1The temperature sensor 128 in the engine is used to estimate the exhaust temperature (T1). In one example, T1 can be monitored at regular intervals (such as every 2 minutes). At 226, the procedure includes determining whether the engine operating time during a driving cycle is higher than a threshold operating time. The threshold operating time can correspond to an operating time higher than the amount of heat generated by combustion that would be sufficient to vaporize moisture accumulated on engine components, including the exhaust manifold. The threshold operating time can be calibrated based on the moisture content accumulated on the engine components. In one example, the controller can use a lookup table to determine the threshold engine operating time, where the input is the moisture content accumulated on the engine components and the output is the threshold engine operating time. As an example, the threshold operating time can increase as the moisture content accumulated on the engine components increases.

[0051] If it is determined that the engine running time is higher than a threshold running time, then at 228, the procedure includes determining whether the exhaust temperature (T1) has been maintained above the threshold temperature (T) for a threshold duration. The threshold temperature (T) may correspond to a temperature above which moisture can evaporate from the exhaust system. The controller may calibrate the threshold temperature based on the boiling point of water. In one example, the threshold temperature may be 100°C. The threshold duration may correspond to the time required for the full volume of moisture accumulated on engine components to vaporize. In one example, the controller may use a lookup table to determine the threshold duration, where the input is the moisture content accumulated on the engine components, and the output is the threshold duration. As an example, the threshold duration may increase as the moisture content accumulated on the engine components increases.

[0052] If it is determined that even if the engine running time is higher than the threshold running time, the exhaust temperature does not remain above the threshold temperature for a duration exceeding the threshold, it can be inferred that sufficient waste heat may not be available during the driving cycle to remove all the moisture accumulated on the engine components. If at 228 it is determined that the engine running time is lower than the threshold running time, it can be inferred that regardless of the exhaust temperature, sufficient time may not be available during the driving cycle to remove all the moisture accumulated on the engine components, and the procedure can proceed directly to step 230.

[0053] At point 230, the controller can estimate a second moisture content in the engine, including the intake and exhaust manifolds, based on each of a first moisture content, the duration of engine operation during a driving cycle (engine running time), and the exhaust manifold temperature during the driving cycle. The second moisture content can be proportional to the first moisture content. In one example, the second moisture content can increase as the first moisture content increases and each of the engine operation duration and exhaust temperature decreases. In another example, the second moisture content can decrease as the first moisture content decreases and each of the engine operation duration and exhaust temperature increases.

[0054] At point 232, a moisture removal process can be initiated immediately after the vehicle is switched off to remove residual moisture (secondary moisture content) from engine components. (See reference) Figure 3 The details of the moisture removal process are described. In one example, the moisture removal process can only be performed when the second moisture content is higher than a second threshold level. In one example, the second threshold moisture content can be a non-zero positive moisture content; above this content, accumulated moisture may damage engine hardware over time. In one example, the second threshold moisture content can be 50% relative humidity.

[0055] If it is determined that the engine running time is higher than the threshold running time and the exhaust temperature remains above the threshold temperature for more than the threshold duration, then at point 234, it can be inferred that the moisture accumulated on the engine has vaporized and may not require further moisture removal.

[0056] Figure 3 An exemplary method 300 is shown that can be implemented to remove moisture accumulated in an engine exhaust system. Method 300 can be as follows: Figure 2 It is part of the method 200 described herein, and can be performed in step 232 of method 200.

[0057] At point 302, the procedure includes determining whether the vehicle is in a key-off state. The key-off state can immediately follow a driving cycle, and can be executed during this period. Figure 2 Method 200. During the vehicle ignition off state, the vehicle may be stationary and may be propelled without using engine torque and / or motor torque. If it is determined that the vehicle is not in the ignition off state, then at 304, the current vehicle operation may be maintained. The current vehicle operation may include using engine torque and / or motor torque to propel the vehicle.

[0058] If it is determined that the vehicle is in the ignition off position, the process of removing moisture from engine components can be initiated. At 306, the controller can send signals to the intake throttle valve (such as...). Figure 1 The controller sends a signal to the actuator of the intake throttle valve 20 to open the throttle valve to the fully open position to allow ambient air to enter the engine intake manifold. This ambient air can be pressurized and directed through the engine intake and exhaust manifolds to remove any accumulated moisture. The controller can also send a signal to a bypass valve connected to the electric air compressor (such as...). Figure 1 The actuator of the bypass valve 161 sends a signal to actuate the bypass valve to the fully closed position. By closing the bypass valve of the electric air compressor, the entire volume of air that has entered the intake manifold via the throttle can flow to the intake manifold via the electric supercharger.

[0059] At 306, it is connected to the exhaust gas recirculation (EGR) passage (such as...). Figure 1 EGR valve (such as EGR channel 180) in the EGR valve Figure 1 The EGR valve 152 can be actuated to the fully open position by the controller to guide compressed air from the intake manifold to the exhaust manifold via the EGR passage. Because the engine is not rotating, the engine valves may not open to allow compressed air to flow through the engine cylinders. Furthermore, the controller can direct the exhaust gas valve (such as...) connected to the exhaust gas passage... Figure 1 The exhaust valve 91 sends a signal to actuate the valve to the fully open position. The exhaust passage provides a lower resistance path for compressed air to flow from the intake manifold to the exhaust manifold relative to the exhaust turbine.

[0060] At point 308, the electric air compressor can be operated to flow pressurized air through the intake and exhaust manifolds to remove moisture. The controller can send commands to the electric air compressor actuators (such as...) Figure 1 The actuator 155b) sends a signal to actuate the electric air compressor using energy from an energy storage device coupled to the electric supercharger. As ambient air enters the intake manifold through a fully open throttle and flows through the electric air compressor, the air is pressurized (compressed) and its temperature may increase. As the hot compressed air flows through the intake manifold, moisture condensed in the intake manifold can vaporize. The pressurized airflow can then remove water vapor and residual moisture from the intake manifold. The pressurized air also removes any condensate accumulated in the supercharged air cooler (CAC), which is coupled to the intake manifold downstream of the electric air compressor. The compressed air can then be directed to the engine exhaust manifold via the EGR passage and the wastegate passage. As the compressed air flows through the exhaust passage, moisture accumulated in the exhaust system can be flushed into the atmosphere via the exhaust tailpipe.

[0061] In one example, as an optional step, at 310, the procedure may include transmission via a motor (such as...) Figure 1The electric motor 52 in the motor uses motor torque to make the engine run without fuel. The controller can send a signal to the actuator of the electric motor to make the engine start running at idle speed (such as equal to or about 400 rpm). Due to the low pressure generated by the engine rotation, pressurized air from the intake manifold can be guided through the engine cylinders to the exhaust manifold. Air can enter the engine cylinders through the corresponding intake valves and exit the cylinders through the corresponding exhaust valves. As the hot, pressurized air flows through the engine cylinders, any moisture trapped in the engine cylinders can be vaporized and removed with the airflow, thereby drying the cylinders. After flowing through the exhaust system, the pressurized air, along with the accumulated moisture, can be guided to the atmosphere through the exhaust tailpipe.

[0062] At point 312, operation of the electric air compressor can continue until moisture has been removed from the engine exhaust manifold. In one example, the duration of operation of the electric air compressor can be proportional to the difference between a second moisture content remaining in the exhaust manifold (as estimated in step 230 of method 200) and a second threshold moisture content (as defined in step 232 of method 200). In one example, the duration of operation of the electric air compressor can increase as the difference increases. The controller can use a lookup table to estimate the duration of operation of the electric air compressor, where the input is the difference between the second moisture content and the second threshold moisture content.

[0063] Figure 4 An exemplary timeline 400 is shown, illustrating the operation of an electric air compressor used to remove water accumulated in engine components. The horizontal line (x-axis) represents time, while the vertical markers t1 to t6 identify key moments in the operation procedure of the electric air compressor.

[0064] The first graph (line 402) shows the vehicle speed over time. The second graph (line 404) shows the engine speed. The third graph (line 406) shows the position of the accelerator pedal, representing the driver's torque demand. The fourth graph (line 408) shows the operation of the motor connected to the HEV. The motor can be operated to provide motor torque to propel the HEV. The fifth graph (line 410) shows the estimated ambient humidity based on input from an ambient humidity sensor connected to the engine intake manifold. The dashed line 411 shows the threshold humidity, above which water from the air can condense on engine components, including the intake manifold. The controller can calibrate the threshold humidity level based on the dew point temperature at the vehicle's location. The sixth graph (line 412) shows the level (amount) of moisture accumulated in the engine exhaust system (including the exhaust manifold and exhaust ducts). The controller estimates the exhaust moisture content based on ambient humidity, local weather conditions (retrieved from an external server via wireless communication, and condensation on the windshield inferred from images of the windshield captured by an onboard camera). Dashed line 412 shows the threshold exhaust moisture content, above which the exhaust moisture content may adversely affect the functionality of the exhaust oxygen sensor. The controller can calibrate the threshold exhaust moisture content based on the operation of the oxygen sensor. The seventh graph (line 414) shows the change in exhaust temperature over time. Dashed line 415 shows the threshold exhaust temperature, above which moisture accumulated in the exhaust system can vaporize. The controller can calibrate the threshold exhaust temperature based on the boiling point of water and the moisture content in the exhaust system. The eighth graph (line 416) shows the electric air compressor (such as...) Figure 1 The operating speed of the electric air compressor 155 is shown, which is connected to a duct in parallel with the intake manifold downstream of the intake compressor and upstream of the boost air cooler (CAC). The ninth curve (line 416) shows the opening of the intake throttle valve. The tenth curve (line 420) shows the opening of the EGR valve connected to the exhaust gas recirculation (EGR) passage, one end of which is connected downstream of both the electric air compressor and the CAC to the intake manifold, while the other end of the EGR passage is connected upstream of the exhaust turbine to the exhaust manifold.

[0065] Before time t1, the vehicle is propelled by engine torque and the HEV motor is not operated. Throttle position is proportional to torque demand, which in turn is based on pedal position. To provide the required boost pressure, the electric air compressor is operated. Based on engine dilution requirements, EGR is not requested during this period and the EGR valve remains in the closed position. Even if the ambient humidity is higher than the threshold humidity 411, the exhaust moisture content remains below the threshold temperature 415 because the exhaust temperature is higher than the threshold temperature 415.

[0066] At time t1, in response to the release of the accelerator pedal and the request to turn off the vehicle key, the vehicle speed decreases to zero and the engine speed also decreases to zero. Between time t1 and t2, during the period when the vehicle key is off, the ambient humidity is recorded. When the exhaust temperature drops below the threshold temperature 415 and the ambient humidity is above the threshold humidity 411, it is inferred that the exhaust moisture content has increased to above the threshold level 413.

[0067] At time t2, the engine starts in response to a vehicle start request. Between times t2 and t3, the EGR valve opens to supply EGR based on engine dilution requirements. Between t2 and t3, as combustion continues, exhaust temperatures rise, causing some of the moisture accumulated in the exhaust manifold to vaporize. However, the engine running time between t2 and t3 is insufficient to remove enough moisture from the exhaust system, and the exhaust moisture content remains above the threshold level 413. At time t3, a decrease in torque demand is inferred in response to a change in pedal position. Between t3 and t4, the engine does not rotate, and the required torque is supplied by operating the electric motor. Because combustion has ceased, waste heat is no longer available for evaporating the moisture accumulated in the exhaust system.

[0068] At time t4, in response to the release of the accelerator pedal and the request to turn off the vehicle key, the vehicle speed decreased to zero and the HEV motor ceased operation. At the time the vehicle key was turned off, it was inferred that the exhaust moisture content remained above the threshold level 413. Based on the moisture content above the threshold 413, it was inferred that residual moisture in the exhaust system could potentially corrode some exhaust system components and adversely affect the operation of the exhaust oxygen sensor during subsequent engine operation. Therefore, after the vehicle key was turned off, an exhaust moisture removal process was initiated (at time t5). At time t4, it was observed that the ambient humidity at the vehicle's current location was below the threshold humidity 411, thereby reducing the likelihood of further moisture condensation on vehicle components.

[0069] At time t5, the intake throttle opening increases to the fully open position, and the controller sends a signal to the electric air compressor actuator to activate the electric compressor. The electric compressor used for moisture removal operates at a higher speed than the electric compressor operating before time t1 (to provide the desired boost pressure). Air compressed by the electric supercharger is directed through the intake manifold to remove any accumulated moisture. The EGR valve is actuated to the fully open position to allow compressed air to flow from the intake manifold to the exhaust manifold via the EGR passage. Between times t5 and t6, compressed air flows through each of the intake manifold, EGR passage, and exhaust manifold, thereby removing moisture from the exhaust system. At time t6, based on the exhaust moisture content at time t5 and the duration of the electric compressor's operation, it is deduced that the compressed air flowing through the exhaust system has been able to remove sufficient moisture from the exhaust system, and the exhaust moisture content has decreased below the threshold 413. Therefore, at time t6, the controller sends a signal to the actuator connected to the electric air compressor to pause the operation of the electric air compressor and resumes the vehicle ignition off state.

[0070] In this way, by operating the electric air compressor while the engine key is off, moisture accumulated in the engine's intake and exhaust manifolds can be removed, thereby reducing engine start-up time and improving the driving experience. Removing water from the exhaust manifold before engine start-up accelerates the heating of the oxygen sensor and reduces water splashing onto it, thus improving measurement accuracy and emissions quality. The timely use of the electric supercharger to dry the exhaust system reduces the likelihood of damage to exhaust system components due to corrosion and rust. Overall, by drying the intake and exhaust manifolds, combustion stability and emissions quality can be improved during subsequent engine combustion.

[0071] An exemplary engine method includes: in response to each of the following: the engine of a vehicle operating for a duration below the threshold during a driving cycle and a moisture content in the engine's exhaust or intake system exceeding the threshold level, activating an electric air compressor in the intake system to remove moisture from at least the exhaust system upon a key-off event following the driving cycle. In any of the foregoing examples, additionally or optionally, activation of the electric air compressor is further based on an exhaust temperature below the threshold during the driving cycle. In any or all of the foregoing examples, additionally or optionally, the moisture content is estimated via an onboard camera configured to determine the amount of moisture on the vehicle's windshield during a previous key-off event. In any or all of the foregoing examples, additionally or optionally, the driving cycle immediately precedes the key-off event, and the previous key-off event immediately precedes the driving cycle. In any or all of the foregoing examples, additionally or optionally, the moisture content is further estimated based on the ambient humidity at the vehicle's location during the previous key-off event. In any or all of the foregoing examples, additionally or optionally, the engine's operating time is a function of the number of start-stop events during the driving cycle, the duration of each start-stop event, the number of deceleration fuel cut-off (DFSO) events, and the duration of each DFSO event. In any or all of the foregoing examples, additionally or optionally, removing moisture from at least the exhaust system includes directing compressed air from the electric air compressor through the intake system and the exhaust system to remove moisture from each of the intake system and the exhaust system to the atmosphere. In any or all of the foregoing examples, additionally or optionally, the electric air compressor is coupled to a duct in parallel with the intake duct, the duct being coupled downstream of the intake compressor and upstream of the boost air cooler to the intake duct, the method further including closing an electric air compressor bypass valve coupled downstream of the intake compressor to the intake duct to direct ambient air into the duct. In any or all of the foregoing examples, additionally or optionally, the engine includes an exhaust gas recirculation passage downstream of the electric air compressor that connects the exhaust system to the intake system, and wherein directing the compressed air through the intake system and the exhaust system further includes opening an exhaust gas recirculation (EGR) valve connected to the exhaust gas recirculation passage to allow compressed air leaving the electric air compressor to flow into the exhaust system. In any or all of the foregoing examples, additionally or optionally, the method further includes, while opening the EGR valve, actuating an intake throttle valve downstream of the boost air cooler connected to the intake manifold to a fully open position, and actuating an exhaust gas valve located in an exhaust gas passage to direct compressed air from the electric air compressor into the exhaust system, the exhaust gas passage being connected in parallel with a turbine located in the exhaust system.In any or all of the foregoing examples, additionally or alternatively, the ambient humidity is measured or inferred based on weather data, including ambient humidity conditions retrieved from an external network communicatively connected to the vehicle via wireless communication.

[0072] Another exemplary engine method includes: estimating a first moisture content in the engine's exhaust system at the start of a vehicle driving cycle; estimating a second moisture content in the exhaust system based on the first moisture content at the end of the driving cycle; and, during a subsequent vehicle key-off state, directing compressed air from the engine intake manifold through the exhaust system in response to the second moisture content being higher than a threshold level. In any of the foregoing examples, additionally or optionally, the first moisture content is estimated based on one or more of the amount of moisture accumulated on the vehicle's windshield during a subsequent previous vehicle key-off state, the change in ambient humidity during the subsequent previous vehicle key-off state, and the dew point temperature at the vehicle's location during the subsequent previous vehicle key-off state. In any or all of the foregoing examples, additionally or optionally, the second moisture content is further based on the duration of engine operation during the driving cycle and the temperature of the exhaust manifold during the driving cycle. In any or all of the foregoing examples, additionally or optionally, directing the compressed air includes operating an electric air compressor coupled to the engine intake manifold to cause compressed air to flow from the intake manifold to the exhaust system. In any or all of the foregoing examples, additionally or optionally, guiding the compressed air further includes opening a throttle valve connected to the intake manifold, opening an EGR valve housed in an exhaust gas recirculation (EGR) passage of an exhaust manifold connecting the intake manifold to the exhaust system, and opening an exhaust gas valve housed in exhaust gas valve passages at both ends of the turbine connected to the exhaust manifold. In any or all of the foregoing examples, additionally or optionally, operating the electric air compressor includes operating the electric air compressor for a period of time based on the difference between the second moisture content and the threshold level, the duration of which increases as the difference increases.

[0073] In yet another example, a system includes: a vehicle, including autonomous vehicles and / or hybrid vehicles; an electric motor coupled to a battery to propel the vehicle; an engine including one or more cylinders, an intake manifold, and an exhaust manifold; an intake duct including a compressor, a boost air cooler (CAC) downstream of the compressor, and an intake throttle valve downstream of the CAC; a duct connected to the intake duct downstream of the compressor and upstream of the CAC, the duct including a motor-driven electric compressor; an electric compressor bypass valve coupled to the junction of the intake duct and the duct; one or more sensors including each of an ambient humidity sensor coupled to the intake manifold and an exhaust temperature sensor coupled to the exhaust manifold; one or more A camera for capturing images of the windshield; an exhaust gas recirculation (EGR) passage downstream of the compressor connecting the exhaust manifold to the intake manifold, the EGR passage including an EGR valve; and a controller having computer-readable instructions stored in a non-transitory memory to: at the end of a driving cycle, estimate the moisture content in the exhaust manifold based on one or more images of the windshield, ambient humidity estimated via the ambient humidity sensor, the duration of engine operation, and changes in exhaust temperature during the driving cycle; and during a subsequent vehicle key off state, in response to a moisture content exceeding a threshold, operate the electric compressor to direct compressed air through the exhaust manifold to remove moisture from the exhaust manifold. In any of the foregoing examples, additionally or alternatively, one or more images of the windshield are captured during a vehicle key off event immediately preceding the driving cycle, and wherein the ambient humidity is monitored during the duration of the vehicle key off event immediately preceding the driving cycle. In any or all of the foregoing examples, additionally or alternatively, the duration of engine operation is estimated based on each of the duration and frequency of one or more of the engine start-stop event and the deceleration fuel cut-off event.

[0074] Note that the exemplary control and estimation programs included herein can be used with various engine and / or vehicle system configurations. The control methods and programs 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 specific programs described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threaded, etc. Therefore, the various actions, operations, or functions shown may be executed sequentially, in parallel, or in some cases omitted. Similarly, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown may be repeatedly executed depending on the specific strategy used. Furthermore, the actions, operations, and / or functions can be graphically represented as code programmed into a non-transitory memory of a computer-readable storage medium in an engine control system, wherein the actions are executed by combining instructions in a system including various engine hardware components with an electronic controller.

[0075] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be considered limiting, as many 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 this 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.

[0076] The following claims specifically point to certain combinations and sub-combinations considered novel and non-obvious. These claims may relate to an “a” element or a “first” element or its equivalent. These claims should be understood to include the introduction of one or more such elements, thus neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment to these claims or by setting new claims in this application or related applications. Such claims, whether broader, narrower, equivalent, or different in scope from the original claims, are considered to be included within the subject matter of this disclosure.

[0077] According to the present invention, a method includes: in response to each of the following: the engine of a vehicle operating time being less than a threshold duration during a driving cycle and the moisture content in the exhaust system or intake system of the engine being higher than a threshold level, activating an electric air compressor in the intake system to remove moisture from at least the exhaust system upon a key-off event following the driving cycle.

[0078] According to one embodiment, the invention is further characterized in that the activation of the electric air compressor is based on an exhaust temperature below a threshold during the driving cycle.

[0079] According to one embodiment, the moisture content is estimated via an onboard camera configured to determine the amount of moisture on the windshield of the vehicle during a previous key-off event.

[0080] According to one embodiment, the invention is further characterized in that the driving cycle immediately precedes the key-off event, and the previous key-off event immediately precedes the driving cycle.

[0081] According to one embodiment, the moisture content is further estimated based on the ambient humidity at the location of the vehicle during the previous key-off event.

[0082] According to one embodiment, the engine's operating time is a function of the number of start-stop events during the driving cycle, the duration of each start-stop event, the number of deceleration fuel cut-off (DFSO) events, and the duration of each DFSO event.

[0083] According to one embodiment, the invention is further characterized in that removing moisture from at least the exhaust system includes directing compressed air from the electric air compressor through the intake system and the exhaust system to remove moisture from each of the intake system and the exhaust system into the atmosphere.

[0084] According to one embodiment, the electric air compressor is connected to a duct in parallel with the intake duct, the duct being connected to the intake duct downstream of the intake compressor and upstream of a booster air cooler. The method further includes closing an electric air compressor bypass valve connected to the intake duct downstream of the intake compressor to direct ambient air into the duct.

[0085] According to one embodiment, the engine includes an exhaust gas recirculation passage downstream of the electric air compressor that connects the exhaust system to the intake system, and wherein directing the compressed air through the intake system and the exhaust system further includes opening an exhaust gas recirculation (EGR) valve connected to the exhaust gas recirculation passage to allow compressed air leaving the electric air compressor to flow into the exhaust system.

[0086] According to one embodiment, the invention is further characterized in that, while opening the EGR valve, the intake throttle valve connected downstream of the boost air cooler to the intake manifold is actuated to the fully open position, and the exhaust valve located in the exhaust valve passage is actuated to guide compressed air from the electric air compressor into the exhaust system, the exhaust valve passage being connected in parallel with the turbine located in the exhaust system.

[0087] According to one embodiment, the ambient humidity is measured or inferred based on weather data, which includes ambient humidity conditions retrieved from an external network communicatively connected to the vehicle via wireless communication.

[0088] According to the present invention, a method includes: at the start of a driving cycle of a vehicle, estimating a first moisture content in the exhaust system of an engine; at the end of the driving cycle, estimating a second moisture content in the exhaust system based on the first moisture content; and during a subsequent vehicle key off state, in response to the second moisture content being higher than a threshold level, directing compressed air from the engine intake manifold through the exhaust system.

[0089] According to one embodiment, the first moisture content level is estimated based on one or more of the following: the amount of moisture accumulated on the windshield of the vehicle during the immediate preceding vehicle key off state, the change in ambient humidity during the immediate preceding vehicle key off state, and the dew point temperature at the location of the vehicle during the immediate preceding vehicle key off state.

[0090] According to one embodiment, the second moisture content is further based on the duration of engine operation during the driving cycle and the temperature of the exhaust manifold during the driving cycle.

[0091] According to one embodiment, the invention is further characterized in that guiding the compressed air includes operating an electric air compressor connected to the engine intake manifold to cause compressed air to flow from the intake manifold to the exhaust system.

[0092] According to one embodiment, the invention is further characterized in that guiding the compressed air includes opening a throttle valve connected to the intake manifold, opening an EGR valve housed in an exhaust gas recirculation (EGR) passage of an exhaust manifold connecting the intake manifold to the exhaust system, and opening an exhaust gas valve housed in an exhaust gas valve passage connected to the exhaust manifold at both ends of the turbine.

[0093] According to one embodiment, operating the electric air compressor includes operating the electric air compressor for a period of time based on the difference between the second moisture content and the threshold level, the duration of which increases as the difference increases.

[0094] According to the present invention, a system is provided, the system comprising: a vehicle, including an autonomous vehicle and / or a hybrid vehicle; an electric motor coupled to a battery to propel the vehicle; an engine including one or more cylinders, an intake manifold, and an exhaust manifold; an intake duct including a compressor, a boost air cooler (CAC) downstream of the compressor, and an intake throttle valve downstream of the CAC; a duct coupled to the intake duct downstream of the compressor and upstream of the CAC, the duct including a motor-driven electric compressor; an electric compressor bypass valve coupled to the junction of the intake duct and the duct; one or more sensors including each of an ambient humidity sensor coupled to the intake manifold and an exhaust temperature sensor coupled to the exhaust manifold; a... One or more cameras for capturing images of the windshield; an exhaust gas recirculation (EGR) passage downstream of the compressor connecting the exhaust manifold to the intake manifold, the EGR passage including an EGR valve; and a controller having computer-readable instructions stored in a non-transitory memory to perform the following operations: at the end of a driving cycle, estimating the moisture content in the exhaust manifold based on one or more images of the windshield, ambient humidity estimated via the ambient humidity sensor, the duration of engine operation, and changes in exhaust temperature during the driving cycle; and immediately afterward, during a subsequent vehicle key-off state, in response to a moisture content exceeding a threshold, operating the electric compressor to direct compressed air through the exhaust manifold to remove moisture from the exhaust manifold.

[0095] According to one embodiment, one or more images of the windshield are captured during a vehicle key off event immediately preceding the driving cycle, and the ambient humidity is monitored during the duration of the vehicle key off event immediately preceding the driving cycle.

[0096] According to one embodiment, the duration of engine operation is estimated based on each of the duration and frequency of one or more of the engine start-stop event and deceleration fuel cut-off event.

Claims

1. An engine method comprising: in response to each of a runtime of an engine of a vehicle during a drive cycle being below a threshold duration and a moisture content in an exhaust system or an intake system of the engine being above a threshold level, activating an electric air compressor in the intake system to expel moisture from at least the exhaust system at a key-off event following the drive cycle.

2. The engine method of claim 1, wherein activating the electric air compressor is further based on being below a threshold exhaust gas temperature during the drive cycle.

3. The engine method of claim 1, wherein the moisture content is estimated via an onboard camera configured to determine an amount of moisture on a windshield of the vehicle during a previous key-off event.

4. The engine method of claim 3, wherein the drive cycle immediately precedes the key-off event and the previous key-off event immediately precedes the drive cycle.

5. The engine method of claim 3, wherein the moisture content is further estimated from an ambient humidity at a location of the vehicle during the previous key-off event, the ambient humidity measured via one or more of an intake humidity sensor, a windshield humidity sensor, or inferred based on weather data, the weather data including ambient humidity conditions retrieved from an external network communicatively coupled to the vehicle via wireless communication.

6. The engine method of claim 1, wherein the runtime of the engine is a function of a number of start-stop events during the drive cycle, a duration of each start-stop event, a number of deceleration fuel shutoff (DFSO) events, and a duration of each DFSO event.

7. The engine method of claim 1, wherein expelling moisture from at least the exhaust system includes directing compressed air from the electric air compressor through the intake system and the exhaust system to remove moisture from each of the intake system and the exhaust system to atmosphere.

8. The engine method of claim 1, wherein the electric air compressor is coupled to a conduit in parallel with an intake tract, the conduit coupled to the intake tract downstream of an intake compressor and upstream of a charge air cooler, the engine method further comprising closing an electric air compressor bypass valve coupled to the intake tract downstream of the intake compressor to direct ambient air into the conduit.

9. The engine method of claim 1, wherein the engine includes an exhaust recirculation passage coupling the exhaust system downstream of the electric air compressor to the intake system, and wherein directing compressed air through the intake system and the exhaust system further includes opening an exhaust recirculation, EGR, valve coupled to the exhaust recirculation passage to flow compressed air exiting the electric air compressor to the exhaust system, and simultaneously with opening the EGR valve, actuating an intake throttle valve coupled to an intake runner downstream of a charge air cooler to a fully open position, and actuating a wastegate valve located in a wastegate passage coupled in parallel to a turbine located in the exhaust system to direct compressed air from the electric air compressor into the exhaust system.

10. A vehicle system comprising: a vehicle including an autonomous vehicle; an electric machine coupled to a battery to propel the vehicle; an engine including one or more cylinders, an intake manifold, and an exhaust manifold; an intake runner including a compressor, a charge air cooler, CAC, downstream of the compressor, and an intake throttle valve downstream of the CAC; a conduit coupled to the intake runner downstream of the compressor and upstream of the CAC, the conduit including a motor-driven electric compressor; an electric compressor bypass valve coupled at a junction of the intake runner and the conduit; one or more sensors including each of an ambient humidity sensor coupled to the intake manifold and an exhaust temperature sensor coupled to the exhaust manifold; one or more cameras to capture images of a windshield; an exhaust recirculation, EGR, passage coupling the exhaust manifold downstream of the compressor to the intake manifold, the EGR passage including an EGR valve; and a controller having computer-readable instructions stored on a non-transitory memory to: estimate a first moisture content in the exhaust manifold at a beginning of a drive cycle of the vehicle; estimate a second moisture content in the exhaust manifold based on the first moisture content at a completion of the drive cycle; and direct compressed air from the engine intake manifold through the exhaust manifold in response to the second moisture content being above a threshold level during an immediately subsequent vehicle key-off condition.

11. The vehicle system of claim 10, wherein the first moisture content is estimated based on one or more of an amount of moisture accumulated on the windshield of the vehicle during an immediately previous vehicle key-off condition, a change in ambient humidity during the immediately previous vehicle key-off condition, and a dew point temperature at a location of the vehicle during the immediately previous vehicle key-off condition.

12. The vehicle system of claim 10, wherein the second moisture content is further based on a duration of operation of the engine during the drive cycle and a temperature of the exhaust manifold during the drive cycle.

13. The vehicle system of claim 10, wherein directing compressed air comprises operating the electric compressor to flow compressed air from the intake manifold to the exhaust manifold.

14. The vehicle system of claim 10, wherein directing compressed air further comprises opening the intake throttle, opening the EGR valve, and opening a wastegate valve housed in a wastegate passage coupled to the exhaust manifold on either side of a turbine.

15. The vehicle system of claim 10, wherein operating the electric compressor comprises operating the electric compressor for a duration of time that increases with an increase in a difference between the second moisture content and the threshold level.

16. A vehicle system comprising: a vehicle comprising a hybrid vehicle; an electric machine coupled to a battery to propel the vehicle; an engine comprising one or more cylinders, an intake manifold, and an exhaust manifold; an intake passage comprising a compressor, a charge air cooler (CAC) downstream of the compressor, and an intake throttle downstream of the CAC; a conduit coupled to the intake passage downstream of the compressor and upstream of the CAC, the conduit comprising a motor-driven electric compressor; an electric compressor bypass valve coupled at a junction of the intake passage and the conduit; one or more sensors comprising each of an ambient humidity sensor coupled to the intake manifold and an exhaust temperature sensor coupled to the exhaust manifold; one or more cameras to capture images of a windshield; an exhaust gas recirculation (EGR) passage coupling the exhaust manifold to the intake manifold downstream of the compressor, the EGR passage comprising an EGR valve; and a controller having computer-readable instructions stored on a non-transitory memory to: estimate a first moisture content in the exhaust manifold at a beginning of a drive cycle of the vehicle; estimate a second moisture content in the exhaust manifold based on the first moisture content at a completion of the drive cycle; and direct compressed air from the engine intake manifold through the exhaust manifold in response to the second moisture content being above a threshold level during an immediately subsequent vehicle key-off condition.

17. The vehicle system of claim 16, wherein the first moisture content is estimated based on one or more of an amount of moisture accumulated on the windshield of the vehicle during an immediately previous vehicle key-off condition, a change in ambient humidity during the immediately previous vehicle key-off condition, and a dew point temperature at a location of the vehicle during the immediately previous vehicle key-off condition.

18. The vehicle system of claim 16, wherein the second moisture content is further based on a duration of operation of the engine during the drive cycle and a temperature of the exhaust manifold during the drive cycle.

19. The vehicle system of claim 16, wherein directing compressed air comprises operating the electric compressor to flow compressed air from the intake manifold to the exhaust manifold.

20. The vehicle system of claim 16, wherein directing compressed air further comprises opening the intake throttle, opening the EGR valve, and opening a wastegate valve housed in a wastegate passage coupled to the exhaust manifold on either side of a turbine.

21. The vehicle system of claim 16, wherein operating the electric compressor comprises operating the electric compressor for a duration of time based on a difference between the second moisture content and the threshold level, the duration of time increasing as the difference increases.

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