Method and system for operating an engine in wet conditions

Abstract

The present disclosure provides a method and system for operating an engine in wet conditions. A method and system are provided for improving the starting of an engine that has been stopped during wet ambient conditions. The method and system can reduce the likelihood of starting an engine with liquid water in the engine cylinders, thereby improving engine starting. In one example, a laser is applied to metal surfaces within the engine to vaporize water that may be present in the engine due to condensation.

Description

Technical Field

[0001] The present application relates to methods and systems for operating an internal combustion engine in the presence of high ambient humidity levels. Background Art

[0002] A vehicle's internal combustion engine can operate under conditions with elevated ambient humidity levels. While the engine is running, moist air can be drawn into the engine, and the engine may perform well because the higher temperature in the engine allows water vapor to remain entrained in the air. The higher humidity of the air acts as a charge diluent, reducing engine knock and NOx emissions. However, if water vapor is allowed to condense within the engine, it can cause engine misfire. If an engine misfire occurs due to water condensation within the engine, engine emissions and performance may be reduced.

[0003] If the engine is stopped, water vapor may be more likely to condense in the engine. Specifically, humid air drawn into the engine while the engine is running may cool after the engine is stopped. Cooling the humid air may lead to condensation within the engine and the formation of water droplets within the engine and the engine air intake system. If the engine is started with water in the engine and / or the engine air intake, water may be drawn into the engine cylinders via the vacuum, where it may cause cylinder misfire. Therefore, it may be desirable to provide a method for reducing the likelihood of liquid water being drawn into engine cylinders. Summary of the Invention

[0004] The inventors herein have recognized the challenges associated with operating an engine in wet ambient conditions and have developed an engine operating method comprising: activating a laser ignition system of an engine and vaporizing water within a cylinder via the laser ignition system in response to an engine start prediction; and reverse rotating the engine in response to the engine start prediction.

[0005] By vaporizing water that may form in the engine cylinders due to condensation, the technical benefit of improved engine starting can be achieved by reducing the likelihood of misfire within the engine. The laser ignition system can be activated in response to a predicted engine start to vaporize water that may be present in the engine cylinders. The engine start prediction can be based on a key fob or other device within a specified distance of the vehicle. Alternatively, the engine start prediction can be based on the opening of a vehicle door or via a remote vehicle start request.

[0006] The method described herein includes several advantages. Specifically, the method can reduce engine emissions. Furthermore, the method can provide improved combustion during engine starting, resulting in smoother engine torque generation during engine starting. Furthermore, the method can improve engine restarting after the engine has been automatically stopped.

[0007] It should be understood that the above summary is provided to introduce in simplified form some concepts that 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 solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0009] Figure 2 Shown Figure 1 An exemplary internal combustion engine of a hybrid vehicle system.

[0010] Figure 3 Shown according to Figure 4 and Figure 5 An exemplary engine operating sequence for the method.

[0011] Figure 4 and Figure 5 A high level flow chart of a method for operating an engine is shown. DETAILED DESCRIPTION

[0012] Methods and systems are described that are provided for reducing water formation within engine cylinders and improving engine starting. Figure 1 and Figure 2 An engine system is shown in which water formation within an engine cylinder can be reduced to improve engine starting. An exemplary engine operating sequence including a predictive engine start is shown in FIG. Figure 3 A method for operating an engine including a laser ignition system is shown in Figure 4 and Figure 5 Shown in.

[0013] Figure 1 A vehicle having a hybrid drive system 10 is schematically depicted. Hybrid drive system 10 includes an internal combustion engine 20 coupled to a transmission 16. Transmission 16 can be a manual transmission, an automatic transmission, or a combination thereof. Furthermore, various additional components can be included, such as a torque converter and / or other gears, such as a final drive unit. Transmission 16 is shown coupled to drive wheels 14, which can contact a road surface.

[0014] In the example, the hybrid drive system also includes an energy conversion device or motor 18 that can be operated as a motor and generator. The energy conversion device 18 is further shown as being coupled to an energy storage device 22, which may include a battery, a capacitor, a flywheel, a pressure vessel, etc. The energy conversion device can be operated to absorb energy from vehicle motion and / or an engine, and convert the absorbed energy into an energy form suitable for storage by the energy storage device (in other words, providing generator operation). The energy conversion device can also be operated to provide output (power, work, torque, speed, etc.) to drive wheels 14 and / or engine 20 (in other words, providing motor operation). It should be understood that the energy conversion device can be operated as both a motor and a generator to provide appropriate energy conversion between the energy storage device and the vehicle drive wheels and / or engine 20.

[0015] The connections depicted between the engine 20, the energy conversion device 18, the transmission 16, and the drive wheels 14 may be mechanical connections, while the connection between the energy conversion device 18 and the energy storage device 22 may be electrical connections. For example, torque may be transferred from the engine 20 to drive the vehicle drive wheels 14 via the transmission 16. As described above, the energy storage device 22 may be configured to operate in generator mode and / or motor mode. In generator mode, the system 10 may absorb some or all of the output from the engine 20 and / or the transmission 16, which may reduce the amount of drive output delivered to the drive wheels 14. In addition, the output received by the energy conversion device 18 may be used to charge the energy storage device 22. Alternatively, the energy storage device 22 may receive charge from an external energy source 24, such as a plug-in to a mains power source. In motor mode, the energy conversion device 18 may provide a mechanical output to the engine 20 and / or the transmission 16, for example, by using electrical energy stored in a battery.

[0016] Hybrid drive examples may include full hybrid systems, in which the vehicle can operate solely on the engine, solely on the energy conversion device (e.g., motor), or solely on a combination of the two. Assisted or mild hybrid configurations may also be employed, in which the engine is the primary source of torque and the hybrid drive system is used to selectively deliver increased torque, such as under high load conditions or other conditions. Additionally, starter / generator and / or intelligent alternator systems may be employed.

[0017] As will be appreciated from the foregoing, the exemplary hybrid drive system is capable of various operating modes. For example, in a first mode, the engine 20 is on and acts as a source of torque to power the drive wheels 14. In this case, the vehicle is operating in an "engine on" mode, and fuel is supplied from the fuel system 28 to the engine 20 (at Figure 2). The fuel system 28 includes a fuel vapor recovery system 29 for storing fuel vapors and reducing emissions from the hybrid vehicle drive system 10.

[0018] In another mode, the drive system can operate using energy conversion device 18 (e.g., an electric motor) as a source of torque to propel the vehicle. This "engine-off" operating mode can be used during braking, at low speeds, when stopped at a traffic light, etc. In another mode, which can be referred to as an "assist" mode, energy conversion device 18 can supplement and cooperate with the torque provided by engine 20. As described above, energy conversion device 18 can also operate in a generator mode, in which torque is absorbed from engine 20 and / or transmission 16. In addition, energy conversion device 18 can be used to increase or absorb torque during transitions of engine 20 between different combustion modes (e.g., during transitions between spark ignition mode and compression ignition mode).

[0019] The above reference Figure 1 The various components described may be controlled by a vehicle control system 41 that includes a controller 12 having computer readable instructions for executing routines and subroutines for regulating vehicle systems, a plurality of sensors 42, and a plurality of actuators 44. The sensors 42 may include Figure 2 The sensor shown is a door position sensor for sensing the state of the driver's door to predict engine start. When the key fob 3 comes within close proximity of the vehicle 1 (e.g., within two meters), the key fob 3 can transmit a security token (e.g., a sequence of numbers) to the receiver 2. The security token can allow the vehicle 1, including the energy conversion device 18 and the engine 20, to be started. When the key fob 3 is within a predetermined distance of the vehicle 1 (e.g., after the key fob 3 transmits the security token to the receiver 2 via radio frequency), the engine start can be predicted.

[0020] Figure 2 Shown included in such Figure 1 Schematic diagram of exemplary cylinders of a multi-cylinder internal combustion engine 20 in a hybrid vehicle system of a hybrid vehicle of FIG. 1 . Engine 20 may be controlled at least in part by a control system including controller 12 and by input from a human driver 132 via input device 130. In the depicted example, input device 130 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal. Controller 12 receives input from a human driver 132. Figure 1 and Figure 2 The controller 12 also sends signals to the various sensors shown. Figure 1 and Figure 2 The various actuators shown provide signals. Controller 12 operates according to executable instructions stored in non-transitory memory.

[0021] Combustion cylinder 30 of engine 20 may include combustion cylinder 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 a vehicle 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 examples, combustion cylinder 30 may include two or more intake valves and / or two or more exhaust valves.

[0022] In the depicted example, 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 cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems operable by controller 12 to vary valve operation. To enable detection of cam positions, cam actuation systems 51 and 53 may include gears. The positions of intake valve 52 and exhaust valve 54 may be determined by position sensors 55 and 57, respectively. In an alternative example, 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.

[0023] Fuel injector 66 is shown coupled directly to combustion cylinder 30 for injecting fuel directly therein in proportion to the pulse width of a signal received from controller 12. 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 by a fuel delivery system (not shown) including a fuel tank, a fuel pump, and a fuel rail. In some examples, combustion cylinder 30 may alternatively or additionally include a fuel injector arranged in intake passage 43, the configuration of which provides what is known as port injection of fuel into the intake passage upstream of combustion cylinder 30.

[0024] Intake passage 43 may include throttle 62 having throttle plate 64. In the particular example, the position of throttle plate 64 may be varied by controller 12 via a signal provided to an electric motor or actuator included in throttle 62, a configuration which 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, among other engine combustion cylinders. Intake passage 43 may include a mass air flow sensor 120, a manifold air pressure sensor 122, an intake air temperature sensor 72, and an intake air humidity sensor 74 for providing corresponding signals to controller 12.

[0025] Exhaust gas sensor 126 is shown coupled to exhaust passage 48 upstream of catalytic converter 70. Sensor 126 may be any suitable sensor for providing an indication of exhaust gas air / fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide range exhaust gas oxygen sensor), a two-state oxygen sensor or exhaust gas oxygen sensor (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, catalytic converter 70 may include multiple catalyst bricks. In another example, multiple emission control devices may be used, each having multiple bricks. In one example, catalytic converter 70 may be a three-way type catalyst.

[0026] The controller 12 Figure 1 10. The controller 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, a random access memory 108, a keep-alive memory 109, and a data bus. In addition to those signals previously discussed, the controller 12 may also receive various signals and information from sensors coupled to the engine 20, including a sensed mass air flow measurement from a mass air flow sensor 120; engine coolant temperature from a temperature sensor 112 coupled to a cooling sleeve 114; in some examples, optionally including a surface ignition sensing signal from a Hall effect sensor 118 (or other type) coupled to the crankshaft 40; throttle position from a throttle position sensor 63; and a manifold absolute pressure (MAP) signal from a MAP air pressure sensor 122. The storage medium read-only memory chip 106 may be programmed with computer-readable data representing instructions executable by the microprocessor 102 for performing the method described below and variations thereof.

[0027] Engine 20 also includes a laser system 92. Laser 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 converges the laser light generated by laser oscillating portion 86 onto a laser focus 82 of combustion cylinder 30.

[0028] Laser system 92 is configured to operate in more than one capacity. For example, during combustion conditions, laser energy can be used to ignite the air / fuel mixture at a specific crankshaft angle during the compression stroke of the engine, including during engine cranking, engine warm-up, and warm engine operation. Fuel injected by fuel injector 66 can form the air / fuel mixture during at least a portion of the intake stroke, where the air / fuel mixture is ignited using laser energy generated by laser actuator 88 to initiate combustion of the otherwise non-combustible air / fuel mixture and drive piston 36 downward.

[0029] As another example, during non-combustion conditions, when the temperature within engine 20 is within a threshold temperature of the dew point temperature within the engine, laser ignition system 92 can be activated to heat piston 36 or another surface within engine 20. The laser energy can heat piston 36, thereby causing water droplets within engine 20 to evaporate. Under certain conditions, the evaporated water can be expelled from the engine by reversing engine rotation. LCU 90 can direct laser actuator 88 to focus laser energy at different locations and at different power levels depending on operating conditions. For example, during combustion conditions, laser energy can be focused on piston 36 and away from cylinder wall 32. In another example, laser energy can be focused on piston 36 and then on cylinder wall 32 to vaporize water droplets.

[0030] Controller 12 controls LCU 90 and has a non-transitory computer-readable storage medium that includes code for adjusting the location of laser energy delivery based on temperature (e.g., intake air temperature). Laser energy can be directed to different locations within cylinder 30. Controller 12 may also incorporate additional or alternative sensors for determining the operating mode of engine 20, including additional temperature sensors, pressure sensors, humidity sensors, and sensors that detect engine speed, air volume, and fuel injection volume. Additionally or alternatively, LCU 90 may communicate directly with various sensors used to determine the operating mode of engine 20, such as a temperature sensor for detecting ECT.

[0031] As mentioned above, Figure 1Only one cylinder of a multi-cylinder engine is shown, and each cylinder may similarly include its own set of intake / exhaust valves, fuel injectors, laser ignition system, etc.

[0032] Figure 1 and Figure 2 A vehicle system is provided that includes: an engine including a throttle; an electric motor-generator; a laser ignition system coupled to a cylinder head; and a controller including executable instructions to deactivate the laser ignition system and close the throttle in response to an amount of time since a predicted engine start has expired. The system also includes additional instructions to activate the laser ignition system in response to the prediction of starting the engine. The system also includes additional instructions to automatically stop engine rotation. The system also includes additional instructions to activate the laser ignition system while stopping the engine in response to a temperature within the engine being within a dew point temperature threshold. The system also includes additional instructions to open the throttle in response to the prediction of starting the engine.

[0033] Now refer to Figure 3 , showing an exemplary engine operating sequence. Figure 1 and Figure 2 The system provides Figure 3 In addition, according to Figure 4 and Figure 5 The method provides Figure 3 order.

[0034] from Figure 3 The first graph at the top is a graph of engine rotation direction versus time. The vertical axis represents the engine rotation direction, which can be forward (e.g., clockwise) or reverse (e.g., counterclockwise) as indicated along the vertical axis. When trace 302 is in the middle of the vertical axis, the engine is stopped. The horizontal axis represents time, with time increasing from the left side of the graph to the right side. Trace 302 represents the engine rotation direction.

[0035] from Figure 3 The second graph from the top is a graph of laser ignition status versus time. The vertical axis represents the laser ignition status, and when trace 304 approaches the vertical axis arrow, the laser ignition status is on or activated. When trace 304 approaches the horizontal axis, the laser ignition status is off or deactivated. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph. Trace 304 represents the laser ignition status.

[0036] from Figure 3The third graph from the top is a graph of engine throttle position versus time. The vertical axis represents engine throttle position, and when trace 306 approaches the vertical axis arrow, the engine throttle is open. When trace 306 approaches the horizontal axis, the engine throttle is closed. The horizontal axis represents time, and time increases from the left side of the graph to the right side of the graph. Trace 306 represents engine throttle position.

[0037] from Figure 3 The fourth graph from the top is a graph of engine status versus time. The vertical axis represents engine status, and when trace 308 approaches the vertical axis arrow, the engine is on or activated. When trace 308 approaches the horizontal axis, the engine is off or deactivated. The horizontal axis represents time, with time increasing from the left side of the graph to the right side. Trace 308 represents engine status.

[0038] from Figure 3 The fifth graph from the top is a graph of engine temperature versus time. The vertical axis represents engine temperature (e.g., temperature in the engine air intake, temperature in the cylinder, temperature in the intake manifold, or temperature within the intake runners). The horizontal axis represents time and increases in time from the left side of the graph to the right side. Trace 310 represents engine temperature. Horizontal line 350 represents the dew point temperature within the engine under current engine operating conditions.

[0039] from Figure 3 The sixth graph from the top of the graph is a graph of vehicle operating state versus time. The vertical axis represents the vehicle operating state, and when trace 312 approaches the vertical axis arrow, the vehicle operating state is on or activated. When trace 312 approaches the horizontal axis, the vehicle is off or deactivated. The horizontal axis represents time, and time increases from the left side of the graph to the right side. Trace 312 represents the vehicle operating state. When the engine is deactivated, the vehicle operating state may be active.

[0040] At time t0, engine rotation ceases and the laser ignition system is deactivated. The engine throttle is closed and the engine is shut down. The engine temperature is below the dew point temperature of 350°C, so water droplets may have formed within the engine due to condensation. Specifically, warm air drawn into the engine while the engine is shut down may cool, causing water vapor to condense and form liquid water within the engine's air intake system. This liquid water may cause the engine to misfire, thereby increasing engine emissions.

[0041] At time t1, the engine remains stopped, but laser ignition is initiated in response to a predicted engine start. The predicted engine start can occur when a person opens a vehicle door or enters the vicinity of the vehicle using a key fob that provides a security token to the vehicle's controller. In response to the predicted engine start, the engine throttle is also opened. Opening the throttle allows air from the engine to flow into the engine intake, allowing water heated in the engine to vaporize or evaporate, transferring water vapor from hotter parts of the engine to cooler parts of the engine, including the engine intake system upstream of the throttle. Warm air from the engine helps evaporate water in the engine cylinder head and intake, increasing the volume of heated air in the engine prior to engine start. The heated air reduces the amount of water droplets introduced into the engine during the first few combustion events since the most recent engine stop, thereby reducing the likelihood of engine misfire. The engine remains deactivated and the engine temperature remains below the dew point. The vehicle remains off (e.g., torque-driven sources such as the engine and energy conversion device are not activated).

[0042] Between time t1 and time t2, the engine rotates in reverse several times, with the engine stopped before and after each engine revolution. By rotating the engine in reverse, the air heated within the engine can be retained within the engine intake, where it can help evaporate water droplets in the engine intake. If the engine were rotating in the forward direction, the heated air would be exhausted into the exhaust system, where removing water droplets from the engine intake would be futile. The engine rotates in reverse to discharge the contents of the cylinders into the engine intake, where it can help evaporate any water that may be in the engine intake. Furthermore, the contents of one cylinder can be discharged into the engine intake, the engine can then be stopped to heat the contents of a different cylinder, and then the engine can be rotated again to discharge the contents of the different cylinder into the engine intake. Thus, cylinder heating can be performed while the engine is stopped, and the heated contents of the engine cylinders, including water vapor, can then be discharged into the engine intake via the reverse engine rotation. In this way, the heat generated in the engine cylinders by the activated laser system vaporizes water in the cylinders and promotes evaporation of water in the engine air intake. When laser ignition is activated and the engine rotates in reverse, the engine throttle remains open and the engine is shut off. The vehicle also remains shut off. As the laser system heats the air in the engine cylinders and the engine air intake, the engine temperature increases.

[0043] At time t2, the engine temperature exceeds the dew point temperature in the engine by a certain threshold amount, and the laser ignition system is deactivated to reduce energy consumption. In response to the engine temperature being greater than the dew point temperature, the engine throttle is closed and the engine remains off. The vehicle also remains deactivated and engine rotation is stopped.

[0044] At time t3, the engine rotates forward in response to a vehicle start request (not shown). In response to the vehicle start request, the engine and the laser ignition system are also started (e.g., spark and fuel are provided). The engine is started with the throttle closed, and the vehicle is started (e.g., power is supplied to the vehicle drive source) in response to the vehicle start request.

[0045] Between time t3 and time t4, the engine is running and the engine temperature increases. As the engine temperature increases, water droplets are less likely to form in the engine air intake because the temperature in the engine is likely above the dew point. The vehicle remains started and the engine throttle is opened and closed in response to driver demand torque (not shown). Laser ignition remains active to support combustion in the engine, and the engine rotates in the forward direction.

[0046] At time t4, engine rotation is stopped while the vehicle remains started. When the driver demand torque is low, the engine can be automatically stopped via the controller (e.g., in response to a vehicle input other than a dedicated driver input, such as a key switch or button, to stop the engine) to save fuel. The throttle is closed, and the laser ignition system is deactivated in response to the automatic engine stop. Engine temperature is at a high level.

[0047] Between time t4 and time t5, the engine temperature decreases and the vehicle remains started. The engine remains stopped and the engine is not rotating. The laser ignition remains deactivated and the engine throttle remains closed.

[0048] At time t5, the engine temperature is within the threshold temperature of the dew point temperature 350. Therefore, laser ignition is initiated to heat the contents of the engine cylinder. When the laser is directed onto a metal surface within the engine (e.g., a piston or cylinder wall), it generates heat within the engine. This heating prevents condensation within the engine cylinder, preventing the formation of water droplets within the engine. By reducing the likelihood of water droplet formation within the engine, the likelihood of misfire within the engine is reduced. The engine remains deactivated and not rotating. The engine throttle is closed and the vehicle remains started.

[0049] At time t6, laser ignition is deactivated to conserve electrical energy. The engine remains deactivated and the engine throttle remains closed. The engine temperature has risen above the dew point temperature of 350°C and the vehicle remains started.

[0050] At time t7, the engine automatically restarts and the engine rotates forward. Laser ignition is activated to support combustion within the engine, and the engine throttle is closed to limit engine torque output during engine startup. The engine starts and the engine temperature begins to rise. The vehicle remains started.

[0051] In this way, when water droplets may form in the engine, the laser ignition system can be activated to heat the contents of the engine cylinder. The laser ignition system can also keep the contents of the engine warm during conditions where the engine can automatically restart so that water droplets do not form in the engine.

[0052] Now turn Figure 4 and Figure 5 , routine 400 depicts a method for operating an engine. Figure 4 and Figure 5 The method can be combined with Figure 1 and Figure 2 In addition, Figure 4 and Figure 5 At least portions of the method may be incorporated as executable instructions stored in non-transitory memory, while other portions of the method may be executed via a controller that transforms the operating states of devices and actuators in the physical world. The engine controller described herein also includes instructions for operating the engine under the conditions described herein.

[0053] At 402, the method determines whether the vehicle is running. The vehicle may be operated in response to a request by a human driver or an autonomous driver to operate the vehicle. In one example, the vehicle may be requested to run when a key fob comes into proximity with the vehicle (e.g., within 2 meters of the vehicle) and the key fob transmits a security token recognized by the vehicle's controller. When the vehicle is running, one or more of the vehicle's drivetrain torque sources (e.g., an engine or motor) may be started (e.g., providing power). Method 400 may determine that the vehicle is started when one of the vehicle's drive torque sources is started or when a key fob or similar device is brought into proximity with the vehicle. If method 400 determines that the vehicle is running, then the answer is yes, and method 400 proceeds to Figure 5 Otherwise, the answer is no, and method 400 proceeds to 404.

[0054] At 404, method 400 determines whether an engine start is predicted. Method 400 may predict that the vehicle's engine will start when a vehicle door is opened or when the key fob is within a predetermined distance of the vehicle. Door opening or the key fob entering the vicinity of the vehicle may be precursor events that can be used to predict an engine start. Battery state of charge and driver demand torque may also be conditions that can predict an engine start. It may be necessary to predict an engine start before requesting an actual engine start so that the engine contents (e.g., air and water droplets) can be heated before the engine starts. By heating the cylinder contents, the likelihood of an engine misfire caused by water droplets in the cylinders can be reduced. When the engine is stopped and engine temperature decreases, water droplets may be generated by condensation in the engine from warm, humid air. If method 400 predicts an engine start, the answer is yes and method 400 proceeds to 406. Otherwise, method 400 returns to 402. If an engine start is not predicted, it may be desirable to conserve power by not activating the laser.

[0055] At 406, method 400 activates the laser ignition system and heats engine components by focusing laser energy on metal surfaces within the engine (e.g., a piston). The amount of power output from the laser can be adjusted in response to the temperature within the engine cylinder. The temperature within the engine cylinder can be inferred from the intake manifold temperature or it can be measured directly. The laser ignition system can be activated by supplying power to the laser ignition system via an electrical energy storage device. Method 400 proceeds to 408.

[0056] At 408 , method 400 opens the engine throttle (eg, Figure 1 62). When the engine rotates in reverse, the throttle valve may be opened to allow heated air from the engine cylinders to flow from the engine cylinders into the engine intake, thereby heating water droplets that may be in the engine intake to promote evaporation of the water droplets. Method 400 proceeds to 410.

[0057] At 410, method 400 rotates the engine in reverse. When the engine is burning air and fuel (e.g., clockwise), reverse rotation is opposite to the direction of engine rotation. By rotating the engine in reverse, the contents of the engine cylinders (e.g., air and water vapor) can be evacuated to the engine intake, where the heated contents can help promote the evaporation of water from the engine intake system rather than losing heat energy to the exhaust system. The engine can be rotated in reverse via an electric machine (e.g., an energy conversion device). When the engine is rotating in reverse, the engine is not burning air and fuel.

[0058] like Figure 3As shown, the engine may continue to reverse direction, or it may reverse direction to evacuate the contents of a single cylinder to the engine intake before stopping the engine rotation to allow further heating of the contents of other engine cylinders. For example, for a four-cylinder, four-stroke engine, method 400 may reverse direction to rotate the engine 180 crankshaft degrees to evacuate the contents of the engine cylinders to the intake manifold. Once the cylinder contents are evacuated to the engine intake, the engine is stopped and the contents of the engine cylinders are further heated. The engine is then reverse direction to evacuate the contents of a different engine cylinder before stopping the engine rotation. This process may be repeated several times. Method 400 proceeds to 412.

[0059] At 412, method 400 determines whether a threshold amount of time to perform an engine start has expired since the predicted engine start. In other words, method 400 may determine whether a threshold amount of time has expired since the predicted engine start at 404 when an engine start has not been requested. In one example, the threshold amount of time may be adjusted in response to engine operating conditions. For example, if the vehicle has just been started after an extended period of inactivity, the threshold amount of time may be shorter. Additionally, if the battery state of charge is high, the threshold amount of time to start the engine after the vehicle has been started may be longer. If the battery state of charge is low, the threshold amount of time to start the engine after the vehicle has been started may be shorter. If method 400 determines that the threshold amount of time to start the engine has expired since the predicted engine start, the answer is yes, and method 400 proceeds to 450. Otherwise, the answer is no, and method 400 proceeds to 414.

[0060] At 450 , method 400 deactivates the laser ignition system. The laser ignition system may be deactivated by stopping power from being supplied to the laser ignition system. Method 400 proceeds to 452 .

[0061] At 452 , method 400 stops rotating the engine in reverse. If the energy conversion device is activated, method 400 may deactivate the energy conversion device. Method 400 proceeds to exit.

[0062] At 414, method 400 determines whether an engine cranking start is requested (e.g., rotating the engine at a speed less than engine idle speed via the energy conversion device). In one example, if the battery state of charge is less than a threshold, method 400 may determine that an engine cranking start is requested. Alternatively or in addition, if the driver demand torque is greater than a threshold, method 400 may determine that an engine cranking start is requested. If method 400 determines that an engine cranking start is requested, the answer is yes, and method 400 proceeds to 455. Otherwise, the answer is no, and method 400 proceeds to 416.

[0063] At 455 , method 400 closes the engine throttle. The engine throttle is closed to limit engine torque during the engine cranking process. Method 400 proceeds to 456 .

[0064] At 456, method 400 cranks the engine forward to start the engine. The engine may be rotated via an energy conversion device or an engine starter. Spark and fuel are also supplied to the engine to start the engine. After cranking and starting the engine, method 400 proceeds to exit.

[0065] At 416, method 400 determines whether the engine temperature is at a desired level. In one example, the engine temperature is the temperature within the engine cylinders. In another example, the engine temperature is the temperature in the engine intake manifold. In yet another example, the engine temperature is the temperature in the engine intake system upstream of the engine throttle. If method 400 determines that one or more engine temperatures are at a desired temperature (e.g., a threshold temperature above the dew point temperature), the answer is yes, and method 400 proceeds to 418. Otherwise, the answer is no, and method 400 returns to 406.

[0066] At 418 , method 400 stops rotating the engine in reverse (eg, in a direction opposite to the direction the engine rotates when the engine is burning air and fuel). Engine rotation may be stopped by stopping power to the energy conversion device. Method 400 proceeds to 420 .

[0067] At 420, method 400 maintains the temperature in the engine. The temperature in the engine can be maintained by selectively activating and deactivating the laser ignition system to maintain the temperature in the engine. If the engine begins to cool above a desired temperature, the laser ignition system can be activated. If the engine temperature increases above a desired temperature, the laser ignition system can be deactivated. Method 400 returns to 412.

[0068] At 430, method 400 determines whether the engine rotation has stopped. When the battery state of charge is greater than a threshold charge, the engine rotation may be automatically stopped in response to the driver demanding a torque less than a threshold torque to save fuel. In addition, in response to the vehicle stopping and / or the vehicle traveling on a road with a negative grade, the engine rotation may be automatically stopped. Method 400 may automatically stop the engine without the driver specifically requesting the engine to stop via a controller input (e.g., an ignition switch or button) dedicated to receiving human driver input to stop the engine. When the engine position does not change within a predetermined amount of time, method 400 may determine that the engine rotation has stopped. If method 400 determines that the engine has stopped, the answer is yes, and method 400 proceeds to 432. Otherwise, the answer is no, and method 400 proceeds to 460.

[0069] At 460, the engine is operated by combusting air and fuel within the engine via a laser ignition system. Air is supplied to the engine via an open throttle valve, and fuel is supplied to the engine via a fuel injector. The fuel and air are ignited via the laser ignition system. Method 400 proceeds to exit.

[0070] At 432, method 400 determines whether an engine start is predicted. Method 400 may predict that the vehicle's engine will start when the battery state of charge decreases to less than a threshold charge. For example, if the battery state of charge is 40%, the battery charge decreases at a rate of 1% per minute, and the engine is started at a battery state of charge of 30% to recharge the battery, method 400 may predict that the engine will restart within 10 minutes. Similarly, method 400 may predict that the engine will restart due to increasing driver demand torque. For example, if the driver demand torque is 100 Newton-meters, increasing at 10 Newton-meters per second, and the engine is started at a requested torque of 200 Newton-meters, method 400 may predict that the engine will start within 10 seconds. The engine start may be predicted for up to a predetermined amount of time (e.g., 10 minutes). If method 400 predicts or forecasts that the engine start will occur within the predetermined amount of time, the answer is yes, and method 400 proceeds to 434. Otherwise, the answer is no, and method 400 returns to 402 .

[0071] At 434, method 400 determines whether the engine temperature is within a threshold temperature for the dew point temperature within the engine or whether the engine has been stopped (not rotating) for more than a threshold amount of time. If the engine temperature is within a threshold temperature for the dew point temperature within the engine, then water vapor in the engine may be about to condense within the engine. Alternatively, if the dew point within the engine cannot be reliably determined due to, for example, a degraded sensor, method 400 may determine whether the engine has been stopped for a predetermined amount of time to estimate whether condensation may be forming within the engine. If method 400 determines that the engine temperature is within a threshold temperature for the dew point temperature within the engine or if the engine has been stopped (not rotating) for more than a threshold amount of time, then the answer is yes and method 400 proceeds to 436. Otherwise, the answer is no and method 400 returns to 402.

[0072] At 436, method 400 activates the laser ignition system and heats engine components by focusing laser energy on metal surfaces within the engine (e.g., a piston). The amount of power output from the laser can be adjusted in response to the temperature within the engine cylinder. The temperature within the engine cylinder can be inferred from the intake manifold temperature or it can be measured directly. The laser ignition system can be activated by supplying power to the laser ignition system via an electrical energy storage device. Method 400 proceeds to 438.

[0073] At 438, method 400 maintains the temperature in the engine. The temperature in the engine can be maintained by selectively activating and deactivating the laser ignition system to maintain the temperature in the engine. If the engine begins to cool above a desired temperature, the laser ignition system can be activated. If the engine temperature increases above a desired temperature, the laser ignition system can be deactivated. Method 400 proceeds to 440.

[0074] At 440, method 400 determines whether a threshold amount of time to perform an engine start has expired since the predicted engine start. In other words, method 400 may determine whether a threshold amount of time has expired since the predicted engine start at 432 without requesting an engine start. In one example, the threshold amount of time may be adjusted in response to engine operating conditions. For example, if the vehicle has just been started after an extended period of inactivity, the threshold amount of time may be shorter. Additionally, if the battery state of charge is high, the threshold amount of time to start the engine after the vehicle has been started may be longer. If the battery state of charge is low, the threshold amount of time to start the engine after the vehicle has been started may be shorter. If method 400 determines that the threshold amount of time to start the engine has expired since the predicted engine start, the answer is yes, and method 400 proceeds to 470. Otherwise, the answer is no, and method 400 proceeds to 442.

[0075] At 470 , method 400 deactivates the laser ignition system. The laser ignition system may be deactivated by stopping power from being supplied to the laser ignition system. Method 400 proceeds to exit.

[0076] At 442, method 400 determines whether an engine cranking start (e.g., rotating the engine at a speed less than engine idle speed via the energy conversion device) and an engine start are requested. In one example, if the battery state of charge is less than a threshold, method 400 may determine that an engine cranking start and start are requested. Alternatively or in addition, if the driver demand torque is greater than a threshold, method 400 may determine that an engine cranking start and start are requested. If method 400 determines that an engine cranking start and start are requested, the answer is yes, and method 400 proceeds to 480. Otherwise, the answer is no, and method 400 returns to 402.

[0077] At 480, method 400 cranks the engine forward to start the engine. The engine may be rotated via an energy conversion device or an engine starter. Spark and fuel are also supplied to the engine to start the engine. After cranking and starting the engine, method 400 proceeds to exit.

[0078] In this way, energy from the laser ignition system can be applied to the engine to heat the contents of the engine cylinders and the engine intake to reduce the amount of liquid fuel in the engine. By reducing the amount of liquid fuel in the engine and intake system, the likelihood of engine misfire can be reduced.

[0079] Figure 4 and Figure 5 A method for operating an engine is provided, the method comprising: receiving sensor input from a controller to predict an engine start; activating a laser ignition system of the engine in response to the engine start prediction and vaporizing water within a cylinder via the laser ignition system; and reverse-rotating the engine in response to the engine start prediction. The method includes: wherein activating the laser ignition system includes operating a laser ignition device to direct a laser pulse into the cylinder. The method includes: wherein activating the laser ignition system is further responsive to an estimation of condensation within the cylinder. The method includes: wherein the estimation of condensation is based on a dew point temperature.

[0080] In some examples, the method further includes opening an engine throttle in response to an engine start prediction. The method includes wherein the engine rotates in reverse via the electric machine. The method further includes deactivating the laser ignition system when the engine does not start within a threshold amount of time of the predicted engine start. The method further includes reversing engine rotation so that the engine rotates in a forward direction in response to the engine start request. The method further includes closing the engine throttle in response to the engine start request.

[0081] Figure 4 and Figure 5 The method also provides an engine operating method, the method comprising: automatically stopping rotation of the engine; and activating a laser ignition system while stopping the engine immediately after the automatic engine stop, in response to a temperature within the engine being within a dew point temperature threshold. The method also comprises estimating the dew point temperature within the engine. The dew point temperature can be estimated using known methods. The method comprises: wherein estimating the dew point temperature comprises estimating humidity within the engine. The method also comprises deactivating the laser ignition system in response to the engine not starting within a threshold amount of time after activating the laser ignition system. The method also comprises opening a throttle of the engine in response to the temperature within the engine being within a dew point temperature threshold. The method also comprises automatically restarting the engine in response to the temperature within the engine being within a dew point temperature threshold.

[0082] 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 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, and the like. Therefore, the various actions, operations, and / or functions shown may be performed in the order shown, in parallel, or omitted in some cases. Likewise, the order of processing is not necessarily required to achieve the features and advantages of the exemplary examples described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown may be repeated depending on the specific strategy used. Furthermore, the actions, operations, and / or functions described may graphically represent code to be programmed into non-transitory memory of a computer-readable storage medium in an engine control system.

[0083] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific examples should not be construed in a limiting sense, as many variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, and other features, functions, and / or properties disclosed herein.

[0084] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. These 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, equal, or different in scope to the original claims, are deemed included within the subject matter of the present disclosure.

[0085] According to the present invention, there is provided an engine operating method having: activating a laser ignition system of an engine in response to engine start prediction and vaporizing water in a cylinder via the laser ignition system; and reversely rotating the engine in response to the engine start prediction.

[0086] According to one embodiment, activating the laser ignition system includes operating the laser ignition device to direct laser pulses into the cylinder.

[0087] According to one embodiment, the laser ignition system is activated further in response to an estimation of condensation within the cylinder.

[0088] According to one embodiment, the estimation of condensation is based on the dew point temperature.

[0089] According to one embodiment, the above invention is further characterized by opening an engine throttle in response to said engine start prediction.

[0090] According to one embodiment, the engine rotates in reverse via an electric machine.

[0091] According to one embodiment, the above invention is further characterized by deactivating the laser ignition system when the engine does not start within a threshold amount of time of predicting the engine start.

[0092] According to one embodiment, the above invention is further characterized by reversing engine rotation so that the engine rotates in a forward direction in response to an engine start request.

[0093] According to one embodiment, the above invention is further characterized by closing an engine throttle in response to the engine start request.

[0094] According to the present invention, there is provided an engine operating method having: automatically stopping rotation of an engine; and activating a laser ignition system while stopping the engine in response to a temperature within the engine being within a dew point temperature threshold.

[0095] According to one embodiment, the above invention is further characterized by estimating the dew point temperature within said engine.

[0096] According to one embodiment, estimating the dew point temperature comprises estimating the humidity within the engine.

[0097] According to one embodiment, the above invention is further characterized by deactivating the laser ignition system in response to the engine not starting within a threshold amount of time of activating the laser ignition system.

[0098] According to one embodiment, the above invention is further characterized by opening a throttle of the engine in response to the temperature within the engine being within the threshold of the dew point temperature.

[0099] According to one embodiment, the above invention is further characterized by automatically restarting the engine in response to the temperature within the engine being within the threshold temperature of the dew point temperature.

[0100] According to the present invention, a vehicle system is provided having an engine including a throttle; an electric motor-generator; a laser ignition system coupled to a cylinder head; and a controller including executable instructions to deactivate the laser ignition system and close the throttle in response to expiration of an amount of time to start the engine since a predicted engine start.

[0101] According to one embodiment, the above invention is further characterized by additional instructions for activating the laser ignition system in response to a prediction of starting the engine.

[0102] According to one embodiment, the above invention is also characterized by an additional instruction to automatically stop the rotation of the engine.

[0103] According to one embodiment, the above invention is further characterized by activating the laser ignition system while stopping the engine in response to the temperature within the engine being within a dew point temperature threshold.

[0104] According to one embodiment, the above invention is further characterized by an additional command to open the throttle valve in response to a prediction of starting the engine.

Claims

1. A method for operating an engine, comprising: activating a laser ignition system of an engine in response to an engine start prediction and vaporizing water within a cylinder via the laser ignition system; rotating the engine in reverse in response to the engine start prediction; and The laser ignition system is deactivated when the engine does not start within a threshold amount of time of predicting the engine start.

2. The method of claim 1 , wherein activating the laser ignition system comprises operating a laser ignition device to direct laser pulses into the cylinder.

3. The method of claim 1 , wherein the laser ignition system is activated further in response to an estimation of condensation within the cylinder. The method of claim 3 , wherein the estimation of condensation is based on dew point temperature. 5 . The method of claim 1 , further comprising opening an engine throttle in response to the engine start prediction. The method of claim 1 , wherein the engine is reversely rotated via an electric motor. 7 . The method of claim 1 , further comprising reversing engine rotation so that the engine rotates forward in response to an engine start request. 8 . The method of claim 7 , further comprising closing an engine throttle in response to the engine start request.

9. A vehicle system comprising: an engine including a throttle valve; electric motor-generator; a laser ignition system coupled to the cylinder head; as well as A controller includes executable instructions to deactivate the laser ignition system and close the throttle valve in response to expiration of an amount of time to start the engine since a predicted engine start.

10. The system of claim 9, further comprising additional instructions for activating the laser ignition system in response to a prediction of starting the engine.

11. The system of claim 9, further comprising additional instructions to automatically stop rotation of the engine.

12. The system of claim 9, further comprising activating the laser ignition system while stopping the engine in response to a temperature within the engine being within a dew point temperature threshold.

13. The system of claim 9 further comprising additional instructions to open the throttle valve in response to a prediction of starting the engine.

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