Method and system for engine control

Abstract

This disclosure provides a method and system for engine control. These methods and systems are used to dry engine cylinders in situ in response to engine flooding. In one example, a laser ignition device is sequentially operated in each engine cylinder while the cylinder is parked with its intake valve closed and exhaust valve open. Heat generated by the laser operation vaporizes liquid fuel in the cylinder, which then flows out of the cylinder through the open exhaust valve, thereby accelerating cylinder drying.

Description

Technical Field

[0001] The present description generally relates to methods and systems for resolving engine flooding. Background Art

[0002] An engine ignition system may include a spark plug, which is used to deliver electrical current to the combustion chamber of a spark-ignition engine (such as a gasoline engine) to ignite the air-fuel mixture and initiate combustion. Spark plug fouling can occur when the spark plug's insulator's ignition tip becomes coated with foreign matter, such as fuel or soot. A soot-fouled spark plug involves carbon accumulation on the spark plug's electrode, while a wet-fouled spark plug involves liquid fuel accumulation around the electrode. For example, a spark plug may become wet-fouled due to engine flooding. During extreme temperature weather conditions, when the driver repeatedly depresses / bumps the accelerator during a crank start, an engine may flood due to a rich fuel supply or due to excess fuel in the cylinder (e.g., due to a degraded fuel injector). When spark plugs become wet-fouled, they are unable to produce a spark across the electrode, thereby delaying or preventing engine starting. When the cylinder includes other forms of ignition, engine flooding can also affect other in-cylinder components and delay engine starting. In some cases, engine flooding may cause a frustrated vehicle driver to continue cranking the engine until the battery is depleted. Additionally, vehicle emissions may increase due to repeated unsuccessful cranking attempts when the engine is flooded.

[0003] Common service remedies for flooded engines include removing the spark plugs and drying them with compressed shop air or a heat gun. Other remedies involve letting the engine sit for a period of time to allow the fuel in the cylinders to vaporize. However, these methods are invasive and / or time-consuming. Furthermore, the vehicle operator may be unable to start the engine upon request.

[0004] Other attempts to address spark plug wet fouling in less invasive ways include methods for removing fuel adhering to the spark plug while the spark plug remains in the engine. An exemplary method is shown in US Pat. No. 7,523,744 B2 to Ayame et al. This document discloses a method for cranking an engine without injecting additional fuel in response to an indication that the engine has not started properly (e.g., within a duration of initiating a crank start).

[0005] However, the inventors herein have recognized potential issues with such systems. As an example, cranking an engine without providing additional airflow to dry the spark plugs (or other flooded cylinder components) can be inefficient, resulting in an increased number of engine starts. The increased number of engine starts can increase vehicle driver frustration and drain the battery. Furthermore, with repeated and unsuccessful cranking of a flooded engine, tailpipe emissions can increase. Other approaches may rely on an electric supercharger to blow air into the engine cylinders while cranking the engine unfueled to dry the spark plugs. However, such approaches may be limited to vehicle systems equipped with an electric supercharger. Summary of the Invention

[0006] In one example, the aforementioned problem may be addressed by a method comprising, in response to an engine being flooded with fuel during an engine start attempt, cutting off fuel delivery to a cylinder of the engine and operating a laser ignition device to vaporize the fuel while maintaining an exhaust valve of the cylinder open and an intake valve of the cylinder closed. In this manner, the flooded combustion chamber may be effectively and non-intrusively dried.

[0007] As an example, an engine system may be configured with laser ignition. If a controller determines that engine flooding has occurred during engine starting (such as in response to the engine not starting after a cranking start and / or based on rich UEGO sensor output during starting), a drying procedure may be initiated. During the drying procedure, the engine may be rotated unfueled via a motor to bring a first engine cylinder to a stop with the intake valve closed and the exhaust valve open (such as at the top of the exhaust stroke). While the engine remains in this position, a laser igniter may be operated for a duration to vaporize the liquid fuel in the cylinder. If the laser is steerable, the beam direction and focus may be adjusted (e.g., randomly or in a targeted manner) to focus on different areas of the cylinder in order to vaporize the fuel throughout the cylinder. Since the exhaust valve is open, the vaporized fuel is directed out of the cylinder and into the exhaust passage, resulting in rapid and efficient drying of the given cylinder. The engine may then be rotated via a motor to bring a second engine cylinder to a stop with the intake valve closed and the exhaust valve open, and this cylinder may be dried using laser operation. In the same way, all engine cylinders can be dried sequentially, after which the engine start can be restarted.

[0008] In this way, engine flooding can be addressed without removing cylinder components or additional hardware. By using heat generated by a laser igniter coupled to the cylinder to dry the engine, engine start times can be reduced and engine start reproducibility improved. Furthermore, battery drain can be reduced. Overall, wet-fouled cylinder components can be dried more quickly. By improving the quality of engine starts, vehicle driver frustration is reduced.

[0009] It should be understood that the above Summary is provided to introduce a series of concepts in a simplified form, which are further described in the Detailed Description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims that follow the Detailed Description. Furthermore, the claimed subject matter is not limited to implementations that address any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 A schematic diagram illustrating an exemplary vehicle system having an engine configured with laser ignition is shown.

[0011] Figure 2 A high-level flow chart depicts an exemplary method for resolving engine flooding by generating heat in the engine cylinders using a laser igniter.

[0012] Figure 3 An exemplary map for selecting cylinder locations for initiating laser-based cylinder drying is shown.

[0013] Figure 4 A prophetic example of utilizing heat generated by a laser ignition system to dry a flooded engine cylinder is shown. DETAILED DESCRIPTION

[0014] The following description relates to methods for mitigating engine systems configured with laser ignition, such as Figure 1 In response to an indication of engine flooding, the controller may execute a control routine such as Figure 2 ) to dry the engine cylinders using heat generated by operation of the laser igniter. The controller may sequentially deactivate each cylinder as shown in the reference Figure 3 The laser igniter is then operated with the intake valve closed and the exhaust valve open, allowing vaporized fuel to flow from the cylinder into the exhaust system. Figure 4 An exemplary drying operation is shown.

[0015] Go to Figure 1 , depicts an exemplary hybrid propulsion system 10. The hybrid propulsion system may be configured in a passenger road vehicle, such as a hybrid electric vehicle 5. The hybrid propulsion system 10 includes an internal combustion engine 20. The engine 20 may be a multi-cylinder internal combustion engine, one cylinder of which is Figure 1Engine 20 may be controlled at least partially by a control system including controller 12 and by input from a vehicle operator 132 via an input device 130. In this example, input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP.

[0016] Combustion cylinder 30 of engine 20 may include combustion chamber walls 32 with piston 36 positioned therein. Piston 36 may be coupled to crankshaft 40 so that reciprocating motion of the piston is translated into rotational motion of the crankshaft. Crankshaft 40 may be coupled to at least one drive wheel of propulsion system 10 via an intermediate transmission system. Combustion cylinder 30 may receive intake air from intake manifold 45 via intake passage 43 and may exhaust combustion gases via exhaust passage 48. Intake manifold 45 and exhaust passage 48 may selectively communicate with combustion cylinder 30 via respective intake valve 52 and exhaust valve 54. In some embodiments, combustion cylinder 30 may include two or more intake valves and / or two or more exhaust valves.

[0017] In the example shown, intake valve 52 and exhaust valve 54 may be controlled by cam actuation via respective cam actuation systems 51 and 53. Cam actuation systems 51 and 53 may each include one or more cams and may utilize one or more of a cam profile switching system (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) system operable by controller 12 to vary valve operation. To enable detection of cam positions, cam actuation systems 51 and 53 may include gears. The position of intake valve 52 and exhaust valve 54 may be determined by cam position sensors 55 and 57, respectively. In alternative embodiments, intake valve 52 and / or exhaust valve 54 may be controlled by electric valve actuation. For example, cylinder 30 may alternatively include an intake valve controlled by electric valve actuation and an exhaust valve controlled by cam actuation (including CPS and / or VCT systems).

[0018] Fuel injector 66 is shown directly coupled to combustion cylinder 30 for injecting fuel directly into combustion cylinder 30 in proportion to pulse width signal FPW received from controller 12 via electronic driver 68. In this manner, fuel injector 66 provides what is known as direct injection of fuel into combustion cylinder 30. For example, the fuel injector may be mounted on the side of the combustion cylinder or in the top of the combustion cylinder. Fuel may be delivered to fuel injector 66 via a fuel delivery system (not shown) including a fuel tank, a fuel pump, and a fuel rail. Fuel injector 67 is shown arranged in intake passage 43 in a configuration that provides what is known as port injection of fuel into the intake port upstream of combustion cylinder 30. Fuel injector 67 delivers fuel into the intake port in proportion to pulse width signal FPW-2 received from controller 12 via electronic driver 69. In this manner, fuel injector 67 provides what is known as port injection of fuel into combustion cylinder 30.

[0019] In addition to throttle 62 including throttle plate 64, intake passage 43 may also include a charge motion control valve (CMCV) 74 and CMCV plate 72. In this particular example, the position of throttle plate 64 may be varied by controller 12 via a signal (TP) provided to an electric motor or actuator included with throttle 62. This configuration may be referred to as electronic throttle control (ETC). In this manner, throttle 62 may be operated to vary the intake air provided to combustion cylinder 30 as well as other engine combustion cylinders. Intake passage 43 may include a mass air flow sensor 120 and a manifold air pressure sensor 122 for providing respective signals MAF and MAP to controller 12.

[0020] Intake passage 43 may also include one or more temperature and / or pressure sensors for estimating ambient conditions. For example, intake passage 43 may include an intake air temperature (IAT) sensor 172 for estimating the temperature of intake air being drawn into the intake manifold and thereupon into the engine cylinders. Intake passage 43 may also include a barometric pressure sensor 173 for estimating ambient pressure, and a humidity sensor 174 for estimating ambient humidity. During engine operation, one or more engine operating parameters, such as throttle position, engine dilution, valve timing, etc., may be adjusted based on ambient temperature, pressure, and / or humidity. As described in detail herein, intake air temperature sensor 172 may also be used to diagnose the cylinder laser ignition system during select key-off conditions.

[0021] Exhaust gas sensor 126 is shown coupled to exhaust passage 48 upstream of emission control device 70. Emission control device (ECD) 70 may include one or more catalytic converters and a particulate matter filter. Sensor 126 may be any suitable sensor for providing an indication of exhaust air-fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen sensor), a two-state exhaust gas oxygen sensor or EGO, HEGO (heated EGO), NO x , HC, or CO sensors). The exhaust system may include a light-off catalyst and an underbody catalyst, as well as exhaust manifold, upstream, and / or downstream air-fuel ratio sensors. In one example, ECD 70 may include multiple catalyst bricks. In another example, multiple emission control devices may be used, each having multiple bricks. In one example, ECD 70 may be a three-way catalyst.

[0022] In yet another example, ECD 70 may include a particulate matter filter for retaining particulate matter (PM) emissions (such as soot and ash) from the exhaust before releasing the gases into the atmosphere via the tailpipe. The filter may include one or more temperature and / or pressure sensors, such as temperature sensor 182, for estimating the PM load on the filter. The sensors may be coupled to the filter, or multiple sensors may be coupled across the filter. For example, PM load may be inferred based on a pressure or temperature difference across the filter. As described in detail herein, temperature sensor 182 may also be used to diagnose the cylinder laser ignition system during selected key-off conditions.

[0023] The controller 12 Figure 1Controller 12 is shown as a microcomputer comprising a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values ​​(shown in this particular example as a read-only memory chip 106), random access memory 108, keep-alive memory 109, and a data bus. Controller 12 may receive various signals and information from sensors coupled to engine 20. In addition to those previously discussed, these signals include: a measurement of intake mass air flow (MAF) from mass air flow sensor 120; engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114; and, in some examples, optionally, a surface ignition probe (PIP) signal from Hall effect sensor 118 (or other type of sensor) coupled to crankshaft 40; throttle position (TP) from a throttle position sensor; and a manifold absolute pressure (MAP) signal from sensor 122. Hall effect sensor 118 may optionally be included in engine 20, as it functions in a similar capacity to the engine laser system described herein. Storage medium read-only memory 106 can be programmed with computer readable data representing instructions executable by processor 102 for performing the methods described below and variations thereon.

[0024] Engine 20 also includes a laser ignition system 92 for igniting the air-fuel mixture in cylinder 30. Laser ignition system 92 includes a laser driver 88 and a laser control unit (LCU) 90. LCU 90 causes laser driver 88 to generate laser energy. LCU 90 can receive operating instructions from controller 12. Laser driver 88 includes a laser oscillating portion 86 and a light converging portion 84. Light converging portion 84 focuses the laser light generated by laser oscillating portion 86 onto a laser focus 82 of combustion cylinder 30. In one example, light converging portion 84 can include one or more lenses.

[0025] A photodetector 94 may be located in the top of the cylinder 30 as part of the laser system 92 and may receive return pulses from the top surface of the piston 36. The photodetector 94 may include a camera with a lens. In one example, the camera is a charge-coupled device (CCD). The CCD camera may be configured to detect and read the laser pulses emitted by the LCU 90. In one example, when the LCU emits laser pulses in the infrared frequency range, the CCD camera may operate to receive these pulses in the infrared frequency range. In such an embodiment, the camera may also be referred to as an infrared camera. In other embodiments, the camera may be a full-spectrum CCD camera capable of operating in both the visible and infrared spectrums. The camera may include a lens (such as a fisheye lens) for focusing the detected laser pulses and generating an image of the cylinder interior. After the laser is emitted from the LCU 90, the laser is swept across the interior of the cylinder 30. In one example, during laser firing of the cylinder and during conditions where the cylinder piston position is to be determined, the laser may be swept across the interior of the cylinder at the laser focus 82. The camera in the photodetector 94 may detect the light energy reflected from the piston 36.

[0026] It should be understood that while the laser system 92 is shown mounted to the top of the cylinder, in alternative examples the laser system may be configured with the laser actuator mounted on the side of the cylinder, generally facing the valve.

[0027] Laser system 92 is configured to operate in more than one capacity, with the timing and output of each operation based on the engine position of the four-stroke combustion cycle. For example, laser energy can be used to ignite the air / fuel mixture during the power stroke of the engine (including during engine cranking, engine warm-up operation, and warmed-up engine operation). Fuel injected by fuel injector 66 can form an air / fuel mixture during at least a portion of the intake stroke, wherein ignition of the air / fuel mixture using laser energy generated by laser actuator 88 initiates combustion of the otherwise non-combustible air / fuel mixture and drives piston 36 downward. In addition, light generated during a cylinder combustion event can be used by photodetector 94 to capture images of the cylinder interior and assess the progress of the combustion event (e.g., for monitoring flame crown progression).

[0028] In the second operating capability, the LCU 90 can deliver low-power pulses to the cylinder. The low-power pulses can be used to determine piston and valve position during a four-stroke combustion cycle. Additionally, upon reactivating the engine from an idle-stop condition, laser energy can be used to monitor engine position, speed, and other parameters to synchronize fuel delivery and valve timing. Furthermore, the light generated by the lower-power laser pulses can be used to capture images of the cylinder interior prior to a combustion event, such as during the intake stroke.

[0029] The controller 12 controls the LCU 90 and has a non-transitory computer-readable storage medium containing code for adjusting the power output and location of the laser energy delivery. The laser energy can be directed to different locations within the cylinder 30. The controller 12 can also incorporate additional or alternative sensors for determining the operating mode of the engine 20, including additional temperature sensors, pressure sensors, torque sensors, and sensors that detect engine speed, air volume, and fuel injection volume.

[0030] As mentioned above, Figure 1 One cylinder of a multi-cylinder engine 20 is shown, and each cylinder may similarly include its own set of intake / exhaust valves, fuel injectors, laser ignition system, etc.

[0031] During select conditions, the engine may flood and wet foul the cylinders, igniter, and other in-cylinder components. For example, during extreme temperature weather conditions, the engine may flood due to a rich fuel supply when the driver repeatedly depresses / bumps the accelerator during a crank start. As another example, the engine may flood due to leaking fuel injectors causing excess fuel to accumulate inside the cylinders. Flooding the engine can make it difficult to ignite the fuel, thereby delaying or preventing engine starting. In some cases, a frustrated vehicle operator may continue to crank the engine, resulting in battery depletion; and / or further bump the accelerator, resulting in additional engine flooding. Additionally, while the engine is flooded, vehicle emissions may degrade due to repeated unsuccessful crank starts. As referenced in Figure 2 As detailed, in response to an indication of flooded cylinders (such as after an unsuccessful engine start), the controller can initiate a drying process in which a laser igniter is used to generate heat in the cylinders to vaporize the liquid fuel and allow the fuel vapor to flow out of the cylinders. By operating the laser in each cylinder sequentially, each cylinder can be effectively dried, enabling a subsequent successful engine start.

[0032] In some examples, vehicle 5 may be a hybrid vehicle having multiple torque sources available to one or more wheels 55. In other examples, vehicle 5 is a conventional vehicle having only an engine, or an electric vehicle having only one or more electric motors. In the illustrated example, vehicle 5 includes engine 10 and electric motor 152. Electric motor 152 may be a motor or a motor / generator. When one or more clutches 156 are engaged, crankshaft 40 of engine 10 and electric motor 152 are connected to wheels 155 via transmission 154. In the depicted example, a first clutch 156 is disposed between crankshaft 40 and electric motor 152, and a second clutch 156 is disposed between electric motor 152 and transmission 154. Controller 12 may send signals to the actuator of each clutch 156 to engage or disengage the clutch, thereby connecting or disconnecting crankshaft 40 from electric motor 152 and components connected thereto, and / or connecting or disconnecting electric motor 152 from transmission 154 and components connected thereto. Transmission 154 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain can be configured in various ways, including as a parallel, series, or series-parallel hybrid vehicle.

[0033] The electric motor 152 receives power from the traction battery 58 to provide torque to the wheels 155. The electric motor 152 may also operate as a generator to provide power to charge the battery 58, such as during braking operations.

[0034] The controller 12 Figure 1 Various sensors receive signals and use Figure 1 The controller may operate various actuators to adjust engine operation based on received signals and instructions stored in the controller's memory. For example, in response to an indication of engine cylinder flooding, such as based on exhaust gas oxygen sensor 126, the controller may operate laser actuator 88 (also referred to herein as a laser igniter) for a duration while the engine is at rest to generate heat to vaporize liquid fuel from the corresponding cylinder.

[0035] In this way, Figure 1A vehicle system is implemented by a component that includes: an engine including a plurality of cylinders, each of the plurality of cylinders including a corresponding laser ignition device and a fuel injector; an intake passage including an intake throttle coupled to a throttle position sensor; an exhaust passage including an exhaust air-fuel ratio sensor; an electric motor; and a controller having computer-readable instructions stored on a non-transitory memory, the computer-readable instructions for: in response to an unsuccessful engine start attempt, indicating engine flooding based on intake throttle position and air-fuel ratio sensor output during the unsuccessful engine start attempt; and in response to the indication of engine flooding, disabling engine fueling and sequentially drying each of the plurality of cylinders via operation of the laser ignition device while maintaining the corresponding cylinder at an exhaust stroke TDC position. In one example, maintaining the corresponding cylinder at the exhaust stroke TDC position includes rotating the unfueled engine via the electric motor to sequentially maintain the corresponding cylinder at the exhaust stroke TDC position. The electric motor can be one of a starter motor coupled to the engine and a propulsion motor coupled to a driveline of a vehicle system. Operating the laser ignition device may include operating at a higher power setting than used for piston position determination.Additionally, the controller may also include instructions for restarting the engine after drying each of the plurality of cylinders.

[0036] Figure 2 An exemplary method 200 is shown for detecting engine flooding and the presence of wet deposits on cylinder components in an engine system, and in response thereto, drying the engine using heat generated via a laser ignition system. For example, method 200 may be performed during an engine start attempt so that engine flooding may be detected during the engine start attempt and the engine cylinders may then be dried before reattempting another engine start. Instructions for carrying out method 200 and the remaining methods included herein may be executed by a controller (e.g., Figure 1 The controller 12) is executed based on instructions stored on the memory of the controller and in conjunction with signals received from sensors of the engine system, such as the above referenced Figure 1 The sensors described (e.g. Figure 1 The controller may employ actuators of the engine system (e.g., exhaust gas sensor 126) according to the methods described below. Figure 1 The laser actuator 88, fuel injector 66, intake valve actuator 52 and exhaust valve actuator 54) are used to adjust engine operation.

[0037] Method 200 begins at 202 and includes estimating and / or measuring operating conditions. Operating conditions may include, for example, ambient temperature, ambient pressure, ambient humidity, throttle position (e.g., based on signal TP output by a throttle position sensor), accelerator pedal position (e.g., signal PP output by a pedal position sensor), exhaust air-fuel ratio (e.g., as determined based on signal UEGO output by an exhaust gas sensor), engine coolant temperature, engine state, and vehicle ignition state. The engine state may refer to whether the engine is on (e.g., operating at a non-zero speed, where combustion occurs in the engine cylinders) or off (e.g., at rest, where combustion does not occur in the engine cylinders). The ignition state of the vehicle may refer to the position of an ignition switch. As an example, the ignition switch may be in an "off" position, indicating that the vehicle is off (e.g., powered off, where the vehicle speed is zero), but in the event that the ignition key is inserted (e.g., by the vehicle driver), indicating that a vehicle start may be requested shortly. As a third example, the vehicle may be on and operating in an electric-only mode, where the electric motor (e.g., Figure 1 The motor 152) supplies torque to propel the vehicle and the engine is off and does not supply torque to propel the vehicle.

[0038] At 204, method 200 includes starting the engine in response to an engine start request. In one example, the engine is started in response to a vehicle operator switching an ignition switch to an "on" position, such as by turning an ignition key, depressing an ignition button, or requesting an engine start from a remote device (such as a key fob, smart phone, tablet, etc.). In another example, the engine is started in response to a vehicle transitioning from an electric-only mode to an engine mode in which combustion occurs in the engine and the vehicle is propelled at least in part by torque from the engine. For example, when the system battery (e.g., Figure 1 The vehicle may transition to engine mode when the state of charge (SOC) of the system battery 58) drops below a threshold SOC. The threshold SOC may be a positive, non-zero battery SOC level below which the system battery may be unable to support or perform other vehicle functions while propelling the vehicle via torque from the electric motor. As another example, the vehicle may transition to engine mode if the vehicle driver torque demand rises above a threshold torque. For example, the threshold torque may be a positive, non-zero amount of torque that cannot be achieved or maintained by an electric motor alone, for example. Starting the engine may include spinning the engine with an electric motor, such as a starter motor or electric motor. The engine may be started at a rotational speed that enables combustion to begin and that enables the engine to maintain momentum during starting, such as a rotational speed in the range of, for example, 50-400 RPM.

[0039] At 206 , a determination is made as to whether engine flooding is detected. Additionally or alternatively, a determination may be made as to whether cylinder component wet fouling is detected. Engine flooding may be detected based on one or more of: a position of a throttle coupled to an intake passage during an engine start attempt, an output of an exhaust gas sensor coupled to an exhaust passage, and a number of engine starts attempted without combustion occurring in the engine cylinders. For example, engine flooding may be indicated (or predicted) by a wide-open throttle (WOT) signal (where the throttle is fully open) generated when a vehicle operator depresses an accelerator pedal to its maximum extent during an engine crank start. In some examples, the controller may be configured to reduce or cease fuel injection during a crank start (such as by reducing or completely suppressing fuel injection pulses) in response to the WOT signal, thereby preventing the spark plug from being coated with fuel. In other examples, a WOT signal during a crank start is indicative of cylinder component wet fouling. As another example, a flooded engine may be inferred by an exhaust gas sensor indicating a rich air-fuel ratio (AFR) during a cranking start (e.g., an AFR determined based on the exhaust gas sensor output is less than a threshold AFR, or richer than the stoichiometric sensor output). As yet another example, a flooded engine (and, for example, igniter wet fouling) may be inferred by an engine failing to start after a predetermined or threshold number of engine starting attempts (wherein combustion does not occur in the engine cylinders).

[0040] If engine flooding is not detected, such as when there is no WOT signal during a cranking start, the determined AFR is not less than a threshold AFR, or the engine is started within a predetermined number of engine start attempts, then method 200 proceeds to 208 and includes delivering fuel to the engine cylinders and providing spark to initiate combustion. For example, fuel may be delivered to the engine cylinders by actuating the fuel injectors with nominal fuel pulse widths corresponding to engine start and given operating conditions. The controller may determine the engine cylinders by factoring in operating conditions including ambient humidity, MAF (e.g., a MAF sensor such as Figure 1 The controller may input operating conditions (such as engine speed and load, engine coolant temperature, ambient temperature, exhaust temperature, MAP, etc.) into one or more lookup tables, algorithms and / or maps and output the spark timing. The signal SA sent to the ignition system at the determined spark timing may trigger a laser ignition system (such as a laser ignition system) from the engine. Figure 1The laser system 92) ignites a laser pulse from a laser igniter to ignite the air-fuel mixture. After 208, the method 200 ends.

[0041] If engine flooding is detected at 206 , method 200 proceeds to 210 and optionally includes notifying the vehicle driver that a drying procedure is about to be performed. For example, a message may be displayed to the vehicle driver, such as on a human-machine interface (e.g., a display device) on the vehicle dashboard, indicating that a drying procedure is being performed and that no further engine starts will be attempted until prompted. If the vehicle driver is notified, the vehicle driver may cease further engine start attempts, thereby avoiding potentially draining the system battery.

[0042] At 212, method 200 includes disabling fuel delivery and spark. In the event of engine flooding, delivering additional fuel may exacerbate wet fouling, increase vehicle emissions, and cause emission control devices (e.g., Figure 1 This can cause degradation of the emission control device 70 and reduced fuel economy. By disabling fuel delivery (such as by maintaining the fuel injector disabled), further wet fouling, emission control device degradation, increased vehicle emissions, and reduced fuel economy can be avoided. When cylinder components are wet fouled, the igniter may be unable to generate a spark in the cylinder, and therefore, actuating spark delivery may be ineffective. For example, disabling spark in response to an indication of engine flooding can reduce energy consumption and prevent excessive cylinder component wear.

[0043] At 214 , the method includes selecting a first cylinder in which to perform the drying procedure. That is, the controller may select the first cylinder for drying. For example, the order in which the cylinders are dried may be based on power balance test results. If engine data indicates that the first group of cylinders produces sufficient torque when fired, then drying of those cylinders may not be necessary (or the first group of cylinders may be assigned a lower drying priority). If engine data indicates that some other cylinders are misfiring due to a rich air-fuel mixture, then these other cylinders may be given a higher drying priority and may be dried first. In another example, the results of an on-board fuel injector diagnostic run by the powertrain control module (PCM) may be used to determine the order of drying, indicating which cylinder's fuel injector is leaking. If the PCM is able to pinpoint the leaking injector, the cylinder coupled to the leaking fuel injector may be prioritized for drying first. Alternatively, based on the results of the fuel injector diagnostic, the controller may proactively dry the cylinder with the identified leaking fuel injector even before a cranking event. In this manner, the controller may select a first cylinder in which to initiate drying, and an order for subsequent cylinders, based on one or more of the torque output of each cylinder of the engine and output of an onboard fuel injector diagnostic program. Specifically, the first cylinder to be dried may be a misfiring cylinder and / or may have a leaking fuel injector.

[0044] In yet other examples, cylinder selection may be based on the engine firing order (e.g., the cylinder that will fire first upon a subsequent engine restart may be selected). As yet another example, cylinder selection may be based on cylinder piston position. For example, the cylinder that is at or closest to the exhaust stroke may be selected as the first cylinder. Alternatively, the cylinders may be dried in a predetermined drying order.

[0045] At 216, the method includes cranking the engine without fuel via a motor (such as an electric starter motor) or an electric motor of a hybrid vehicle's powertrain. Rotating the engine includes rotating the engine in a forward direction in the same direction of rotation as the engine rotation during engine cranking and fueled engine rotation. The engine can be rotated at a speed low enough to slowly stop the engine in a position in which the intake valve of a selected cylinder is closed and the exhaust valve is open. For example, the engine can be rotated at a speed lower than the engine starting rotation speed. In one example, the engine can be rotated at a speed of 300 RPM without fuel via the motor until the cylinder piston is in a position with a timing angle near the top of the exhaust stroke (or TDC).

[0046] In one example, the controller may be a map (such as Figure 3 ). Turning temporarily to Figure 3 , map 300 depicts valve timing and piston position relative to engine position for a given engine cylinder. Map 300 shows engine position in crank angle degrees (CAD) along the x-axis. Curve 310 depicts piston position (along the y-axis), with reference to their position from top dead center (TDC) and / or bottom dead center (BDC), and further with reference to their position within the four strokes of the engine cycle (intake, compression, power, and exhaust). As indicated by sinusoidal curve 310, the piston gradually moves downward from TDC, reaching its lowest point at BDC at the end of the power stroke. The piston then returns to the top at TDC at the end of the exhaust stroke. The piston then moves back downward again toward BDC during the intake stroke, returning to its initial top position at TDC at the end of the compression stroke.

[0047] Curves 302 and 304 depict the valve timing of the exhaust valve (dashed curve 302) and the intake valve (solid curve 304) during engine operation. As shown, the exhaust valve can open just as the piston bottoms out at the end of the power stroke. The exhaust valve can then close when the piston completes the exhaust stroke. In a similar manner, the intake valve can open at or before the beginning of the intake stroke and can close just as the piston bottoms out at the end of the intake stroke. Due to the timing difference between exhaust valve closing and intake valve opening, both the intake and exhaust valves of a given cylinder can be open for a short duration near exhaust stroke TDC (including before the end of the exhaust stroke and after the beginning of the intake stroke), as depicted herein at 306. The period during which these two valves can be open is referred to as positive intake-to-exhaust valve overlap 306 (or simply positive valve overlap).

[0048] During the laser-based drying process, the controller can rotate the engine unfueled to a position where the cylinder being diagnosed is in the exhaust stroke, but outside the positive valve overlap region 306. For example, the engine can be rotated to a position just before TDC of the exhaust stroke, outside the positive valve overlap region. In this position, the intake valve is closed and the exhaust valve is open. Thus, the heat generated in the cylinder by the laser can be used to vaporize the liquid fuel, and the fuel vapor can be directed from the cylinder into the exhaust passage through the open exhaust valve.

[0049] Return to Figure 2 At 218, the method includes operating the laser ignition device of the selected cylinder for a duration to generate heat. The laser ignition device is operated at a higher (or highest) power intensity typically used to initiate combustion in the cylinder. The duration of operation may be adjusted based on the estimated degree of flooding, with the duration increasing as the degree of flooding increases. Alternatively, the laser ignition device may be operated for a fixed, predetermined duration, such as three minutes.

[0050] The engine controller can also adjust the location at which the laser beam is focused, including the direction of the beam and the focal point of the beam. In one example, if the laser is steerable, the laser beam can be focused on different areas of the cylinder in random directions so as to illuminate all areas of the cylinder. Alternatively, the laser beam can be directed toward the cylinder wall. The heat energy generated by the laser operation vaporizes the liquid fuel. Because the exhaust valve is open and the intake valve is closed, the fuel vapor generated by the laser operation is then exhausted from the cylinder and into the exhaust passage. As a result, the cylinder and wet-fouled spark plug are dried without removing any components from the cylinder. Operating the laser for the duration can include the controller sending a duty cycle or pulse width signal to the laser driver to operate the laser at its highest power setting for a defined duration. After the duration of operation, the laser is disabled.

[0051] At 220, a determination is made as to whether all engine cylinders have been sufficiently dried. For example, a determination is made as to whether the drying operations detailed at 216-218 have been performed on all engine cylinders (or on the engine cylinders selected for drying, which may be a subset of all engine cylinders). If not, at 222, the method includes selecting the next cylinder (e.g., the second cylinder) in which to perform the drying procedure. The method then returns to 216 to rotate the engine unfueled via the motor to a position in which the selected cylinder has stopped with the intake valve closed and the exhaust valve open. The method then moves to 218 to operate the laser in the selected cylinder to vaporize the liquid fuel and dry the cylinder. In this manner, the controller may move through multiple iterations of steps 216-222 until all engine cylinders (or at least all selected engine cylinders) have been dried.

[0052] At 224 , once all engine cylinders have been dried, the method includes enabling fuel delivery and spark to the engine. Enabling fuel delivery and spark may include activating a fuel pump to provide fuel at high pressure to the fuel injectors. However, the fuel injectors may not yet be actuated open. In this way, fuel can be prepared for injection in response to an engine start request (such as an engine start request from a vehicle operator). Similarly, enabling spark may include enabling transmission of a spark advance signal from the controller to the laser ignition system in anticipation of an engine start request but not yet having been transmitted. By enabling fuel delivery and spark, combustion can be initiated in the engine cylinders in response to the engine start request.

[0053] At 226 , method 200 optionally includes notifying the vehicle driver that an engine start attempt may be made. For example, a message may be displayed to the vehicle driver, such as on a human-machine interface (e.g., a display device) on the vehicle dashboard, indicating that an engine start attempt may be made. Based on driver input, another engine start attempt may then be performed after the engine has dried. Following 226 , method 200 ends.

[0054] Now go to Figure 4 , shows a prophetic example timeline 400 for drying a flooded engine and any wet fouled cylinder components via laser generated heat. In one example, using Figure 2 An exemplary method of laser operation can detect engine flooding and resolve the problem.

[0055] Timeline 400 depicts the activation state of the electric motor at graph 402, laser ignition operation at graph 404, engine speed (Ne) at graph 406, piston position of a first cylinder at graph (dashed line) 410, piston position of a second cylinder at graph (solid line) 408, and intake throttle (e.g., Figure 1 throttle valve 72). For all of the above graphs, the horizontal axis represents time, where time increases from left to right along the horizontal axis. The vertical axis represents each labeled parameter. In graphs 402 and 404, the vertical axis represents whether the electric motor and laser ignition device are "on" (e.g., actively operating, where a non-zero voltage is supplied) or "off" (e.g., deactivated and not operating, where no voltage is supplied), respectively. In graphs 406 and 412, the vertical axis represents the amount of increase or decrease in engine speed and throttle opening, respectively. For graphs 408 and 410, the vertical axis shows the piston position from bottom dead center ("BDC") to top dead center ("TDC").

[0056] Prior to time t1, the electric motor is on (graph 402) to rotate the crankshaft of the engine in response to an engine start request from a vehicle operator. In one example, the electric motor is a starter motor. In another example, the electric motor is an electric motor included in a hybrid vehicle (e.g., Figure 1152). When the engine is cranked (e.g., cranked), the piston within each cylinder of the engine travels between BDC and TDC. For example, for every 360-degree rotation of the crankshaft, the piston may travel from BDC to TDC and back to TDC. The piston of the first cylinder (graph 410) is 180 degrees out of phase with the second cylinder (graph 408), such that when the piston of the second cylinder is at BDC, the piston of the first cylinder is at TDC (and vice versa). For example, the engine may be an inline four-cylinder engine. During a cranking start, the throttle is fully opened (graph 412), such as due to the vehicle driver fully depressing the accelerator pedal. As a result, the engine is flooded. Due to the flooded engine, the engine does not start, and the start attempt is stopped at time t1, when the electric motor is deactivated. After the electric motor is deactivated and no longer cranking the engine, the piston may continue to move briefly due to momentum, and then come to rest between time t1 and time t2. Also at t1, in response to a failed engine start attempt, the controller (eg, Figure 1 The controller 12) closes the throttle.

[0057] At time t2, in response to an engine flooding condition (eg, as determined based on throttle position, exhaust gas sensor output, and / or engine not started), the controller initiates an engine dry-down routine (such as Figure 2 ). wherein the electric motor is activated at t2, and between t2 and t3, the engine is rotated slowly (e.g., at 300 RPM) and without fuel via the motor until the first cylinder is in a position in which the intake valve is closed and the exhaust valve is open. For example, the engine is rotated until the first cylinder stops at TDC of the exhaust stroke, and then the motor is deactivated and further engine rotation is stopped.

[0058] After stopping the first cylinder at the selected position, between t3 and t4, the laser ignition device of the first cylinder is operated at a high power setting for a duration d1. By operating the laser ignition device, heat is generated in the first cylinder. The heating of the first cylinder vaporizes the liquid fuel in the cylinder, thereby drying the cylinder and any wet, fouled components therein.

[0059] At t4, after the first cylinder has dried, the electric motor is reactivated and the engine is slowly rotated unfueled via the motor until the second cylinder is in a position with the intake valve closed and the exhaust valve open at t5. For example, the engine is rotated until the second cylinder stops at TDC of the exhaust stroke, after which the motor is deactivated and further engine rotation is stopped. After the second cylinder has stopped at the selected position, between t5 and t6, the laser ignition device of the second cylinder is operated at a high power setting for a duration d1. By operating the laser ignition device, heat is generated in the second cylinder. The heating of the second cylinder vaporizes the liquid fuel in the cylinder, thereby drying the cylinder and any wet, fouled components therein.

[0060] In the same manner, the controller continues to use the motor to sequentially position the third cylinder (between t6 and t7), and then the fourth cylinder (between t8 and t9), at TDC of the exhaust stroke, and operates the cylinder's laser ignition device to vaporize the combustion and dry the cylinder (the third cylinder is dried via laser operation between t7 and t8, and the fourth cylinder is dried via laser operation between t9 and t10). In this way, by indexing the engine, the flooded engine can be dried cylinder by cylinder. This reduces the battery SOC, but to a lesser extent than if the flooded engine were continuously rotated via the electric motor.

[0061] At t10, all engine cylinders have been dried, and the vehicle driver is notified that they can resume engine start attempts. At t11, in response to the notification, the driver requests an engine start (such as by actuating an engine ignition button or inserting a key into the ignition). The intake throttle opening increases in association with the engine start request, such as based on the driver's actuation of the accelerator pedal. Between t11 and t12, the engine is cranked via the motor, and the engine speed increases to the cranking speed. At t12, once the engine is successfully cranked, the motor is deactivated and engine fueling and spark are resumed. In this example, cylinder ignition is provided via a laser ignition device. After t12, engine rotation is supported by fueled engine combustion and the engine torque generated by the combustion.

[0062] In this way, Figure 4As shown in an example of , an engine controller may indicate flooding of the engine in response to one or more of an intake throttle position and an exhaust gas sensor output during a failed engine start attempt. Then, in response to the indication, the method includes disabling engine fueling and sequentially drying each engine cylinder via operation of a corresponding cylinder laser ignition device while the engine is at rest; and after drying, reattempting the engine start. In one example, sequentially drying includes: rotating the engine without fuel via an electric motor to a position in which each cylinder is individually held at rest in a position in which the intake valve is closed and the exhaust valve is open, and operating the corresponding cylinder laser ignition device for a duration while the cylinder is in the position. The position may include the end of the exhaust stroke of the cylinder outside of a region of positive intake valve to exhaust valve overlap. Herein, the indication may be responsive to one or more of a wide-open intake throttle position and an exhaust gas sensor output below a threshold. Furthermore, the reattempted engine start is a successful engine start.

[0063] In this way, in response to the determination of engine flooding and wet fouling of in-cylinder components of the engine system, one or more cylinders of the flooded engine can be dried through operation of a laser ignition device while the in-cylinder components remain in the engine. The technical effect of providing heat directly to the cylinders through laser ignition is to accelerate the vaporization of liquid fuel from the flooded engine without requiring additional hardware or removing any components from the engine cylinders. Furthermore, the time before the engine can be started is reduced, thereby reducing vehicle driver frustration and battery power consumption during engine starting. By sequentially drying each cylinder while the engine is stationary, the time before the flooded engine can be restarted is reduced. In this way, after the engine is dried, sufficient battery power is retained for starting the engine and operating the vehicle. By alleviating engine flooding and wet fouling of cylinder components and rapidly drying the cylinders while all in-cylinder components remain in the engine, emissions from the flooded engine can also be reduced.

[0064] An exemplary method for an engine includes, in response to the engine being flooded with fuel during an engine start attempt, cutting off fuel delivery to a cylinder of the engine and operating a laser ignition device to vaporize the fuel while maintaining the cylinder's exhaust valve open and the cylinder's intake valve closed. In the foregoing examples, additionally or alternatively, the method further includes rotating the engine unfueled via an electrically actuated motor to a position in which the cylinder's exhaust valve is open and the cylinder's intake valve is closed, the position including top dead center of the cylinder's exhaust stroke, the engine rotating at a speed below an engine cranking speed. In any or all of the foregoing examples, additionally or alternatively, the laser ignition device operates for a duration based on the degree of flooding of the engine, the duration increasing as the degree of flooding increases. In any or all of the foregoing examples, additionally or alternatively, the cylinder is a first cylinder, the method further including sequentially operating the laser ignition device coupled to each remaining cylinder of the engine to dry the engine. In any or all of the foregoing examples, additionally or alternatively, the method further comprises: performing another engine start attempt after drying the engine. In any or all of the foregoing examples, additionally or alternatively, the method further comprises: selecting the first cylinder and the order of sequentially operating the laser ignition device coupled to each remaining cylinder of the engine based on one or more of the torque output of each cylinder of the engine and the output of an on-board fuel injector diagnostic program. In any or all of the foregoing examples, additionally or alternatively, the first cylinder is a misfiring cylinder and / or has a leaking fuel injector. In any or all of the foregoing examples, additionally or alternatively, the method further comprises: causing the vaporized fuel to flow out of the cylinder through the open exhaust valve and into the exhaust passage. In any or all of the foregoing examples, additionally or alternatively, the engine includes an intake passage having a throttle coupled therein and an exhaust passage having an exhaust gas sensor coupled thereto, the method further comprising indicating flooding of the engine based on at least one of: a position of the throttle during the engine start attempt, an output of the exhaust gas sensor during the engine start attempt, and a threshold number of engine start attempts reached without combustion occurring in the cylinder. In any or all of the foregoing examples, additionally or alternatively, indicating based on the position of the throttle includes indicating flooding of the engine based on the throttle being fully open during the engine start attempt, and wherein indicating based on the output of the exhaust gas sensor includes indicating flooding of the engine based on a richer than stoichiometric output of the exhaust gas sensor.

[0065] Another exemplary method includes: indicating engine flooding in response to one or more of intake throttle position and exhaust gas sensor output during a failed engine start attempt; in response to the indication, disabling engine fueling and sequentially drying each engine cylinder while the engine is at rest via operation of a corresponding cylinder laser ignition device; and reattempting engine start after the drying. In the foregoing examples, additionally or alternatively, the sequential drying includes: rotating the engine unfueled via an electric motor to a position in which each cylinder is individually held at rest in a position in which the intake valve is closed and the exhaust valve is open, and operating the corresponding cylinder laser ignition device for a duration while the cylinder is in the position. In any or all of the foregoing examples, additionally or alternatively, the position includes an end of the exhaust stroke of the cylinder outside of a region of positive intake to exhaust valve overlap. In any or all of the foregoing examples, additionally or alternatively, the indication is responsive to one or more of wide-open intake throttle position and below-threshold exhaust gas sensor output. In any or all of the foregoing examples, additionally or alternatively, the reattempted engine start is a successful engine start.

[0066] Another exemplary vehicle system includes an engine including a plurality of cylinders, each of the plurality of cylinders including a corresponding laser ignition device and a fuel injector; an intake passage including an intake throttle coupled to a throttle position sensor; an exhaust passage including an exhaust air-fuel ratio sensor; an electric motor; and a controller having computer-readable instructions stored on non-transitory memory, the computer-readable instructions for: in response to an unsuccessful engine start attempt, indicating engine flooding based on intake throttle position and air-fuel ratio sensor output during the unsuccessful engine start attempt; and in response to the indication of engine flooding, disabling engine fueling and sequentially drying each of the plurality of cylinders via operation of the laser ignition device while maintaining the corresponding cylinder at an exhaust stroke TDC position. In the foregoing example, additionally or alternatively, maintaining the corresponding cylinder at the exhaust stroke TDC position includes rotating the unfueled engine via the electric motor to sequentially maintain the corresponding cylinder at the exhaust stroke TDC position. In any or all of the foregoing examples, additionally or alternatively, the electric motor is one of a starter motor coupled to the engine and a propulsion motor coupled to a driveline of the vehicle system, and wherein operating the laser ignition device includes operating at a higher power setting than that used for piston position determination. In any or all of the foregoing examples, additionally or alternatively, sequentially drying includes selecting an order for drying each of the plurality of cylinders based on one or more of a cylinder misfire count, an output from a fuel injector diagnostic routine, a first cylinder of the plurality of cylinders being selected earlier in the order in response to a higher misfire count and / or an indication of a leaking fuel injector of the first cylinder, and a second cylinder of the plurality of cylinders being selected later in the order in response to a lower misfire count and / or an indication of a functioning fuel injector of the second cylinder. In another representation, the vehicle system is a hybrid vehicle system.

[0067] It should be noted that the exemplary control and estimation routines included herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a 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 routines described herein may represent one or more of any number of processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). As such, the various actions, operations, and / or functions shown may be performed in the order shown, 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 performed depending on the specific strategy used. In addition, the described actions, operations, and / or functions may graphically represent code to be programmed into the non-transitory memory of a computer-readable storage medium in an engine control system, wherein the described actions are implemented by executing the instructions in conjunction with an electronic controller in a system including various engine hardware components.

[0068] 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 technology can be applied to V-6, inline-4, inline-6, V-12, opposed-4, 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 and other features, functions, and / or properties disclosed herein.

[0069] The following claims particularly point out certain combinations and subcombinations believed to be novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, the same, or different in scope than the original claims, are also deemed to be included within the subject matter of the present disclosure.

[0070] According to the present invention, a method for an engine is provided having: in response to the engine being flooded with fuel during an engine starting attempt, cutting off fuel delivery to a cylinder of the engine and operating a laser ignition device to vaporize the fuel while maintaining an exhaust valve of the cylinder open and an intake valve of the cylinder closed.

[0071] According to one embodiment, the above invention is further characterized in that the engine is rotated without fuel via an electric actuation motor to a position in which the exhaust valve of the cylinder is open and the intake valve of the cylinder is closed, the position including the top dead center of the exhaust stroke of the cylinder, and the engine is rotated at a speed lower than the engine cranking starting speed.

[0072] According to one embodiment, the laser ignition device operates for a duration based on the degree of flooding of the engine, the duration increasing as the degree of flooding increases.

[0073] According to one embodiment, the cylinder is a first cylinder, the method further comprising sequentially operating the laser ignition device coupled to each remaining cylinder of the engine to dry the engine.

[0074] According to one embodiment, the above invention is further characterized in that after drying said engine, another engine starting attempt is performed.

[0075] According to one embodiment, the above invention is further characterized by selecting the first cylinder and the order of sequentially operating the laser ignition device coupled to each remaining cylinder of the engine based on one or more of the torque output of each cylinder of the engine and the output of an on-board fuel injector diagnostic program.

[0076] According to one embodiment, the first cylinder is a misfiring cylinder and / or has a leaking fuel injector.

[0077] According to one embodiment, the above invention is further characterized by causing the vaporized fuel to flow out of the cylinder through the open exhaust valve and into an exhaust passage.

[0078] According to one embodiment, the engine includes an intake passage having a throttle coupled therein and an exhaust passage having an exhaust sensor coupled thereto, the method further comprising indicating the flooding of the cylinder of the engine based on at least one of: a position of the throttle during the engine starting attempt, an output of the exhaust sensor during the engine starting attempt, and a threshold number of engine starting attempts reached without combustion occurring in the cylinder.

[0079] According to one embodiment, indicating based on the position of the throttle includes indicating flooding of the engine based on the throttle being fully open during the engine start attempt, and wherein indicating based on the output of the exhaust gas sensor includes indicating flooding of the engine based on a richer than stoichiometric output of the exhaust gas sensor.

[0080] According to the present invention, a method is provided having the following features: indicating flooding of an engine in response to one or more of intake throttle position and exhaust gas sensor output during a failed engine start attempt; in response to the indication, disabling engine fueling and sequentially drying each engine cylinder via operation of a corresponding cylinder laser ignition device while the engine is at rest; and reattempting engine start after the drying.

[0081] According to one embodiment, the sequential drying includes rotating the engine without fuel via an electric motor to a position in which each cylinder is held stationary one by one in which the intake valve is closed and the exhaust valve is open, and operating the corresponding cylinder laser ignition device for a duration when the cylinder is in said position.

[0082] According to one embodiment, said location comprises the end of the exhaust stroke of said cylinder outside the region of positive intake valve to exhaust valve overlap.

[0083] According to one embodiment, the indication is responsive to one or more of wide-open intake throttle position and below-threshold exhaust gas sensor output.

[0084] According to one embodiment, the re-attempted engine start is a successful engine start.

[0085] According to the present invention, a vehicle system is provided, which has: an engine including a plurality of cylinders, each of the plurality of cylinders including a corresponding laser ignition device and a fuel injector; an intake passage including an intake throttle, the throttle being coupled to a throttle position sensor; an exhaust passage including an exhaust air-fuel ratio sensor; an electric motor; and a controller having computer-readable instructions stored on a non-transitory memory, the computer-readable instructions being used to: in response to an unsuccessful engine starting attempt, indicate engine flooding based on the intake throttle position and the air-fuel ratio sensor output during the unsuccessful engine starting attempt; and in response to the indication of engine flooding, prohibit engine fueling and sequentially dry each of the plurality of cylinders via operation of the laser ignition device while maintaining the corresponding cylinder at an exhaust stroke TDC position.

[0086] According to one embodiment, maintaining the corresponding cylinder at the exhaust stroke TDC position includes rotating the unfueled engine via the electric motor to sequentially maintain the corresponding cylinder at the exhaust stroke TDC position.

[0087] According to one embodiment, the electric motor is one of a starter motor coupled to the engine and a propulsion motor coupled to a driveline of the vehicle system, and wherein operating the laser ignition device includes operating at a higher power setting than used for piston position determination.

[0088] According to one embodiment, the sequentially drying includes selecting a sequence for drying each of the plurality of cylinders based on one or more of a cylinder misfire count, an output from a fuel injector diagnostic routine, a first cylinder of the plurality of cylinders being selected earlier in the sequence in response to a higher misfire count and / or an indication of a leaking fuel injector of the first cylinder, and a second cylinder of the plurality of cylinders being selected later in the sequence in response to a lower misfire count and / or an indication of a functioning fuel injector of the second cylinder.

[0089] According to one embodiment, the controller further includes instructions for restarting the engine after drying each of the plurality of cylinders.

Claims

1. A method for an engine, comprising: In response to the engine being flooded with fuel during an engine starting attempt, fuel delivery to a cylinder of the engine is cut off and a laser ignition device of the cylinder is operated to vaporize the fuel while maintaining an exhaust valve of the cylinder open and an intake valve of the cylinder closed.

2. The method of claim 1, further comprising: The engine is rotated unfueled via an electrically actuated motor to a position in which the exhaust valve of the cylinder is open and the intake valve of the cylinder is closed, the position including top dead center of the exhaust stroke of the cylinder, the engine rotating at a speed below an engine cranking start speed.

3. The method of claim 1, wherein the laser ignition device operates for a duration based on the degree of flooding of the engine, the duration increasing as the degree of flooding increases.

4. The method of claim 1 , wherein the cylinder is a first cylinder, the method further comprising: A corresponding laser ignition device coupled to each remaining cylinder of the engine is sequentially operated to dry the engine.

5. The method of claim 4, further comprising: After drying the engine, another engine start attempt is performed.

6. The method of claim 4, further comprising: The first cylinder and the order of sequentially operating the corresponding laser ignition device coupled to each remaining cylinder of the engine are selected based on one or more of the torque output of each cylinder of the engine and the output of an on-board fuel injector diagnostic program.

7. The method of claim 6, wherein the first cylinder is a misfiring cylinder and / or has a leaking fuel injector.

8. The method of claim 1, further comprising: The vaporized fuel is caused to flow out of the cylinder through the open exhaust valve and into the exhaust passage.

9. The method of claim 1 , wherein the engine includes an intake passage having a throttle valve coupled therein and an exhaust passage having an exhaust gas sensor coupled thereto, the method further comprising: The flooding of the engine is indicated based on at least one of: a position of the throttle during the engine starting attempt, an output of the exhaust gas sensor during the engine starting attempt, and a threshold number of engine starting attempts without combustion occurring in the cylinder.

10. The method of claim 9, wherein indicating based on the position of the throttle comprises: Flooding of the engine is indicated based on the throttle being fully open during the engine start attempt, and wherein indicating based on the output of the exhaust gas sensor includes indicating flooding of the engine based on a richer than stoichiometric output of the exhaust gas sensor.

11. A vehicle system comprising: An engine comprising a plurality of cylinders, each of the plurality of cylinders comprising a corresponding laser ignition device and a fuel injector; an intake passage including an intake throttle valve coupled to a throttle position sensor; an exhaust passage including an exhaust air-fuel ratio sensor; electric motors; as well as a controller having computer-readable instructions stored on a non-transitory memory, the computer-readable instructions for: In response to an unsuccessful engine starting attempt, indicating engine flooding based on intake throttle position and air / fuel ratio sensor output during the unsuccessful engine starting attempt; and In response to the indication of engine flooding, engine fueling is disabled and each of the plurality of cylinders is sequentially dried via operation of the corresponding laser ignition device while maintaining the corresponding cylinder at an exhaust stroke TDC position.

12. The system of claim 11 , wherein maintaining the corresponding cylinder at an exhaust stroke TDC position comprises: An unfueled engine is rotated via the electric motor to sequentially maintain the corresponding cylinders at the exhaust stroke TDC position.

13. The system of claim 12, wherein the electric motor is one of a starter motor coupled to the engine and a propulsion motor coupled to a driveline of the vehicle system, and wherein operating each corresponding laser ignition device comprises: Operate at a higher power setting than used for piston position determination.

14. The system of claim 11, wherein the sequential drying comprises: An order for drying each of the plurality of cylinders is selected based on one or more of a cylinder misfire count, an output from a fuel injector diagnostic routine, a first cylinder of the plurality of cylinders being selected earlier in the order in response to a higher misfire count and / or an indication of a leaking fuel injector of the first cylinder, and a second cylinder of the plurality of cylinders being selected later in the order in response to a lower misfire count and / or an indication of a functioning fuel injector of the second cylinder.

15. The system of claim 11, wherein the controller further comprises instructions for restarting the engine after drying each of the plurality of cylinders.

Images