Engine starting via electric turbocharger

Abstract

The present disclosure provides for "engine starting via an electric turbocharger." Methods and systems for starting an engine via an electric turbocharger are provided. In one example, a method for starting the engine via the electric turbocharger can include flowing compressed air from the electric turbocharger to a cylinder of the engine to turn a crankshaft of the engine to start the engine without a starter motor. The method can include adjusting the opening of electrically or pneumatically actuated intake and exhaust valves to reduce the force used to turn the crankshaft to start the engine.

Description

TECHNICAL FIELD

[0001] The present specification generally relates to methods and systems for controlling an electric turbocharger to start an internal combustion engine of a vehicle. BACKGROUND

[0002] Engine systems often include a starter motor configured to rotate a crankshaft of an engine prior to combustion of fuel and air within cylinders of the engine. The starter motor provides an initial torque source for the engine in order to transition the engine from a stationary mode of operation to a mode of operation in which the engine combusts fuel and air to rotate the crankshaft. However, the starter motor can increase the cost and / or weight of the engine system.

[0003] Attempts to reduce the cost and weight of the starter motor include reducing the size of the starter motor and / or the number of components included in the starter motor, and / or adjusting engine parameters to reduce starter motor load. An example approach is shown in U.S. Patent 6,182,449 to Halimi et al. A dual cycle internal combustion engine is disclosed therein that includes a motor assisted turbocharger that provides pressurized air for operating the engine. The motor assisted turbocharger can be disposed in series with an exhaust driven turbocharger, and during starting, the motor assisted turbocharger can provide pressurized air to the engine. When sufficient air pressure is obtained from the compressor of the motor assisted turbocharger, the engine is started by a starter motor.

[0004] However, the present inventors have recognized potential problems with such systems. As one example, starting of the engine in such systems can rely on both the motor assisted turbocharger and the starter motor. In the event that the compressor of the motor assisted turbocharger is unable to deliver sufficient air pressure, the starter motor can be unable to supply sufficient energy to start the engine. Similarly, in the event that the starter motor experiences degradation or power loss, the engine can be unable to start. SUMMARY

[0005] In one example, the above-described problems can be addressed by a method for an engine, the method comprising: during an engine start request, driving a crankshaft of the engine without combustion by only flowing compressed air from an electric turbocharger to cylinders of the engine and without actuating a starter motor. In this way, the crankshaft can be rotated via only the compressed air in order to start the engine prior to combustion of fuel and air in the engine cylinders.

[0006] As one example, the engine can include electrically or pneumatically actuated intake and exhaust valves, and the opening of the intake and exhaust valves can be adjusted by a controller of the engine during engine starting. The controller can adjust the opening of the intake and exhaust valves so as to reduce the amount of force delivered by pressurized air to move pistons disposed within cylinders of the engine and rotate a crankshaft. In this way, the engine can be cranked without a starter motor, and the cost and weight of the engine can be reduced.

[0007] It is to be understood that the above summary is provided merely for purposes of summarizing an array of concepts that are further described below in the detailed description. It should not be considered that the detailed description is meant to define key or essential features of the claimed subject matter, the scope of which is defined by the claims. Furthermore, the claimed subject matter is not limited to implementations that solve any or all of the disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 A cylinder of an internal combustion engine of a vehicle is schematically illustrated, the cylinder being configured to receive compressed air from an electric turbocharger.

[0009] Figure 2 An engine system including a plurality of cylinders is schematically illustrated, wherein each cylinder is configured to receive compressed air from an electric turbocharger.

[0010] Figure 3 Firing timing and combustion cycles of an engine including three cylinders are illustrated.

[0011] Figure 4 A method for starting an engine by flowing compressed air to cylinders of the engine via an electric turbocharger is illustrated.

[0012] Figure 5 A plot illustrating engine operating parameters of an engine during an engine starting operation via an electric turbocharger is illustrated, the engine including mechanically actuated intake and exhaust valves.

[0013] Figure 6 A plot illustrating engine operating parameters of an engine during an engine starting operation via an electric turbocharger is illustrated, the engine including cam-less intake and exhaust valves. DETAILED DESCRIPTION

[0014] The following description relates to systems and methods for controlling an electric turbocharger to start an internal combustion engine of a vehicle. One vehicle (such as a vehicle 100) is illustrated in FIG. 1. The vehicle 100 includes an engine 102, a turbocharger 104, and a controller 106. The engine 102 is an internal combustion engine that includes a plurality of cylinders 108. The turbocharger 104 is an electric turbocharger that is configured to provide compressed air to the cylinders 108 of the engine 102. The controller 106 is configured to control the turbocharger 104 to provide compressed air to the cylinders 108 of the engine 102. Figure 1The vehicle shown includes an internal combustion engine having a plurality of combustion chambers. In some examples, the engine can include three cylinders, as shown by Figure 2 The cylinders of the engine can have a 2-1-3 cylinder firing order, as shown in Figure 3 Under conditions in which the engine is at rest, an operator of the engine can indicate a desire for an engine start event (e.g., an engine start request can be initiated). In response to the engine start request, an electrically powered turbocharger of the engine can be energized so as to cause a flow of compressed air to the engine cylinders to drive pistons disposed within the cylinders, as shown by Figure 4 The pistons can be driven by the compressed air for a period of time until a threshold speed or threshold number of revolutions of a crankshaft of the engine is reached, at which point a controller of the engine can initiate combustion of fuel and air within the engine cylinders to sustain operation of the engine. In some examples, as shown by Figure 5 The engine can include mechanically actuated intake and exhaust valves, with pressurized intake air flowing into the cylinders with the intake valves in an open position at the time of engine start. In other examples, as shown by Figure 6 The engine can include electrically or pneumatically actuated intake and exhaust valves that can be adjusted by the controller. The controller can adjust the opening of each intake and exhaust valve during engine start so as to reduce the magnitude of the force driving the pistons during start. In this way, the engine can be started from rest without a starter motor by compressed intake air from the electrically powered turbocharger.

[0015] Figure 1 An example of a combustion chamber or cylinder of an internal combustion engine 10 is depicted. The engine 10 can be controlled at least in part by a control system including a controller 12 and inputs from a vehicle driver 130 via an input device 132. In this example, the input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. A cylinder (also referred to herein as a “combustion chamber”) 14 of the engine 10 can include a combustion chamber wall 136 in which a piston 138 is located. The piston 138 can be coupled to a crankshaft 140 such that the reciprocating motion of the piston is converted to rotational motion of the crankshaft. The crankshaft 140 can be coupled to at least one drive wheel of a passenger vehicle via a drivetrain. In addition, a starter motor (not shown) can be coupled to the crankshaft 140 via a flywheel to enable start-up operation of the engine 10.

[0016] The cylinder 14 can receive intake air via a series of intake passages 142, 144, and 146. In addition to the cylinder 14, the intake passage 146 can also communicate with other cylinders of the engine 10. In the example shown by Figure 1 The vehicle 5 includes an electrically powered turbocharger 159. The electrically powered turbocharger 159 is configured to deliver compressed intake air to each of the cylinders (e.g., the cylinder 14) of the vehicle 5.Figure 1 An engine 10 is shown, which is configured with a compressor 174 of an electric turbocharger 159 disposed between intake passages 142 and 144, and an exhaust turbine 176 of the electric turbocharger 159 disposed along an exhaust passage 148. During operation of the engine 10 (e.g., when the engine 10 is on and fuel and air are combusted in one or more cylinders of the engine 10), the compressor 174 may be powered at least partially via the exhaust turbine 176 through a shaft 180. However, in some examples, the exhaust turbine 176 may be optionally omitted, and the compressor 174 may be powered by mechanical input from a motor or the engine. As mentioned herein, the electric turbocharger (e.g., electric turbocharger 159) includes at least one compressor configured to deliver compressed air to the engine cylinders and an electric motor (e.g., electric motor 175) configured to drive (e.g., rotate) the compressor. The electric turbocharger may also include a turbine (e.g., exhaust turbine 176) configured to be driven by exhaust gas flowing out of the engine 10.

[0017] The electric turbocharger 159 includes an electric motor 175 coupled to a compressor 174. The compressor 174 may be referred to herein as an electric air compressor. The electric motor 175 may be selectively actuated by a controller 12 to rotate the compressor 174 and deliver compressed intake air to the cylinders (e.g., cylinder 14) of the engine 10. See, for example, the following reference... Figure 4 The electric motor 175, in response to an engine start request (e.g., during an engine start request, when the engine 10 is off and fuel / air is not burning in the engine cylinders), is actuated by the controller 12 to deliver compressed air to the engine cylinders to move a piston (e.g., piston 138) and rotate the crankshaft 140 of the engine 10 without burning fuel / air in the engine cylinders. After the piston is moved by compressed air, fuel can then be supplied to one or more engine cylinders (e.g., gasoline, diesel, etc., via fuel injectors 166 and / or fuel injectors 170), and a spark can be ignited in one or more engine cylinders (e.g., via spark plug 192) to burn the fuel / air in the engine cylinders and start the engine 10. The following references... Figures 4 to 6 Describe further examples.

[0018] A throttle valve 162, including a throttle plate 164, can be positioned along the engine's intake passage to alter the flow rate and / or pressure of the intake air supplied to the engine cylinders. For example, the throttle valve 162 can be located downstream of the compressor 174, such as... Figure 1 As shown, or alternatively, it can be located upstream of compressor 174.

[0019] In addition to cylinder 14, exhaust passage 148 can receive exhaust gas from other cylinders of engine 10. An exhaust sensor 128 is shown coupled to exhaust passage 148 upstream of an emission control device 178. Sensor 128 can be selected from a variety of suitable sensors to provide an indication of exhaust gas air-fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide range exhaust gas oxygen), a billet oxygen sensor or EGO (as depicted), a HEGO (heated EGO), a NOx, HC, or CO sensor. Emission control device 178 can be a three-way catalyst (TWC), a NOx trap, various other emission control devices, or combinations thereof.

[0020] Each cylinder of engine 10 can include one or more intake valves and one or more exhaust valves. For example, cylinder 14 is shown including at least one intake valve 150 and at least one exhaust valve 156 located at an upper region of cylinder 14. In some examples, each cylinder of engine 10, including cylinder 14, can include at least two intake valves and at least two exhaust valves located at an upper region of the cylinder.

[0021] Intake valve 150 can be controlled by controller 12 via actuator 152. Similarly, exhaust valve 156 can be controlled by controller 12 via actuator 154. During some conditions, controller 12 can alter the signal provided to actuators 152 and 154 to control the opening and closing of the respective intake and exhaust valves. The position of intake valve 150 and exhaust valve 156 can be determined by respective valve position sensors (not shown). The valve actuators can be electrically actuated, cam actuated, or combinations thereof. The intake and exhaust valve timing can be controlled simultaneously or any of a variety of configurations can be used, such as variable intake cam timing, variable exhaust cam timing, dual independent variable cam timing, or fixed cam timing. Each cam actuation system can include one or more cams and can 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) systems, which can be operated by controller 12 to vary the operation of the valves. For example, cylinder 14 can alternatively include an intake valve controlled by electrically actuated valve and an exhaust valve controlled by cam actuation including a CPS and / or VCT. In other examples, the intake and exhaust valves can be controlled by a common valve actuator or actuation system or a variable valve timing actuator or actuation system.

[0022] Cylinder 14 may have a compression ratio, which is the ratio of the volume when piston 138 is at bottom dead center to that at top dead center. In one example, the compression ratio is in the range of 9:1 to 10:1. However, in some examples using different fuels, the compression ratio may be increased. This may happen, for example, when using fuels with higher octane ratings or fuels with higher potential enthalpy of vaporization. The compression ratio may also be increased if direct injection is used due to its effect on engine knock.

[0023] In some examples, each cylinder of engine 10 may include a spark plug 192 for initiating combustion. In a selected operating mode, ignition system 190 may provide an ignition spark to combustion chamber 14 via spark plug 192 in response to a spark advance signal SA from controller 12. However, in some embodiments, spark plug 192 may be omitted, such as when engine 10 can initiate combustion by automatic ignition or by fuel injection (as is the case with some diesel engines).

[0024] In some examples, each cylinder of engine 10 may be configured with one or more fuel injectors for supplying fuel thereto. As a non-limiting example, cylinder 14 is shown as including two fuel injectors 166 and 170. Fuel injectors 166 and 170 may be configured to deliver fuel received from fuel system 8. (See reference...) Figure 2 and Figure 3 As described in detail, the fuel system 8 may include one or more fuel tanks, a fuel pump, and a fuel rail. A fuel injector 166 is shown directly coupled to the cylinder 14 for injecting fuel directly into the cylinder in proportion to the pulse width FPW-1 of a signal received from the controller 12 via an electronic driver 168. In this way, the fuel injector 166 provides so-called direct fuel injection (hereinafter referred to as "DI") into the combustion cylinder 14. Although Figure 1 The injector 166 is shown located on one side of cylinder 14, but it can optionally be located on top of the piston, such as near spark plug 192. Since some alcohol-based fuels have low volatility, such a location can promote mixing and combustion when the engine is operated with alcohol-based fuels. Alternatively, the injector can be located on top and close to the intake valve to promote mixing. Fuel can be delivered from the fuel tank of fuel system 8 to the fuel injector 166 via a high-pressure fuel pump and fuel rail. Furthermore, the fuel tank may have a pressure sensor that provides a signal to controller 12.

[0025] The fuel injector 170 is shown disposed in the intake passage 146 rather than in the cylinder 14, which is configured to provide so-called port fuel injection (hereinafter referred to as "PFI") into the intake passage upstream of the cylinder 14. The fuel injector 170 can inject fuel received from the fuel system 8 in proportion to the pulse width of a signal FPW-2 received from the controller 12 via an electronic driver 171. Note that a single driver 168 or 171 can be used for both fuel injection systems, or as depicted, multiple drivers can be used, such as driver 168 for fuel injector 166 and driver 171 for fuel injector 170.

[0026] In alternative examples, each of the fuel injectors 166 and 170 can be configured as direct fuel injectors for injecting fuel directly into the cylinder 14. In yet other examples, each of the fuel injectors 166 and 170 can be configured as port fuel injectors for injecting fuel upstream of the intake valve 150. In still other examples, the cylinder 14 can include only a single fuel injector configured to receive different relative amounts of different fuels from the fuel system as a fuel mixture and further configured to inject the fuel mixture directly into the cylinder as a direct fuel injector or upstream of the intake valve as a port fuel injector. Thus, it should be appreciated that the fuel system described herein should not be limited by the particular fuel injector configurations described herein by way of example.

[0027] During a single cycle of the cylinder, fuel can be delivered to the cylinder by both injectors. For example, each injector can deliver a portion of the total fuel injection combusted in the cylinder 14. Further, the distribution and / or relative amounts of fuel delivered from each injector can vary with operating conditions, such as engine load, knock, and exhaust gas temperature, among others as described below. Port injected fuel can be delivered during an open intake valve event, a closed intake valve event (e.g., substantially prior to the intake stroke), and during open and closed intake valve operation. Similarly, for example, direct injected fuel can be delivered during the intake stroke and partially during the preceding exhaust stroke, during the intake stroke, and partially during the compression stroke. Thus, even for a single combustion event, injected fuel can be injected from the port injector and the direct injector at different timings. Further, for a single combustion event, multiple injections of delivered fuel can be performed per cycle. Multiple injections can be performed during the compression stroke, the intake stroke, or any suitable combination thereof.

[0028] Fuel injectors 166 and 170 can have different characteristics. These include dimensional differences, such as one injector having a larger injection orifice than the other. Other differences include, but are not limited to, different injection angles, different operating temperatures, different orientations, different injection timing, different injection characteristics, different locations, etc. Moreover, different effects can be achieved depending on the split ratio of fuel injected between injectors 170 and 166.

[0029] The fuel tanks in fuel system 8 can contain different fuel types of fuel, such as fuels having different fuel qualities and different fuel compositions. These differences can include different alcohol content, different water content, different octane ratings, different heat of vaporization, different fuel mixtures, and / or combinations thereof, etc. One example of fuels having different heat of vaporization can include gasoline as a first fuel type having a lower heat of vaporization and ethanol as a second fuel type having a greater heat of vaporization. In another example, the engine can use gasoline as a first fuel type and an alcohol-containing fuel mixture, such as E85 (approximately 85% ethanol and 15% gasoline) or M85 (approximately 85% methanol and 15% gasoline) as a second fuel type. Other possible substances include water, methanol, mixtures of alcohols, mixtures of water and methanol, mixtures of alcohols, etc.

[0030] In yet another example, both fuels can be alcohol mixtures having different alcohol compositions, where the first fuel type can be a gasoline alcohol mixture having a lower alcohol concentration, such as E10 (approximately 10% ethanol), and the second fuel type can be a gasoline alcohol mixture having a higher alcohol concentration, such as E85 (approximately 85% ethanol). Additionally, the first and second fuels can also differ in other fuel qualities, such as differences in temperature, viscosity, octane rating, etc. Moreover, the fuel characteristics of one or both fuel tanks can change frequently, such as due to daily variations in fuel tank refueling.

[0031] Controller 12 is configured to control the operation of fuel system 8 in a number of ways, including by controlling the operation of fuel injectors 166 and 170. For example, controller 12 can control the operation of fuel injectors 166 and 170 to inject fuel into the engine in a number of ways, including by controlling the amount of fuel injected, the timing of the fuel injection, the fuel split ratio between the two fuel injectors, etc. Figure 1The controller 12 can receive signals from various sensors coupled to the engine 10, including a measurement of intake mass air flow (MAF) from a mass air flow sensor 122; engine coolant temperature (ECT) from a temperature sensor 116 coupled to the cooling jacket 118; a surface ignition sensing signal (PIP) from a Hall effect sensor 120 (or other type) coupled to the crankshaft 140; throttle position (TP) from a throttle position sensor; and absolute manifold pressure signal (MAP) from a sensor 124. An engine speed signal RPM can be generated by the controller 12 from the signal PIP. The manifold pressure signal MAP from the manifold pressure sensor can be used to provide an indication of the vacuum or pressure in the intake manifold. The controller 12 can infer engine temperature based on the engine coolant temperature.

[0032] The controller 12 receives signals from various sensors of the engine 10 and, based on the received signals and instructions stored in the memory of the controller, adjusts engine operation with various actuators of the engine 10. For example, adjusting the flow of compressed air from the electric turbocharger 159 can include adjusting an actuator (e.g., an electric motor 159) of the compressor 174 to adjust the output of the compressor 174 (e.g., the amount of compressed intake air flowing from the compressor 174 to the engine cylinders). Further examples are described below with reference to FIGS. 2-4. Figure 1 The controller 12 receives signals from various sensors of the engine 10 and, based on the received signals and instructions stored in the memory of the controller, adjusts engine operation with various actuators of the engine 10. For example, adjusting the flow of compressed air from the electric turbocharger 159 can include adjusting an actuator (e.g., an electric motor 159) of the compressor 174 to adjust the output of the compressor 174 (e.g., the amount of compressed intake air flowing from the compressor 174 to the engine cylinders). Further examples are described below with reference to FIGS. 2-4. Figure 1 The controller 12 receives signals from various sensors of the engine 10 and, based on the received signals and instructions stored in the memory of the controller, adjusts engine operation with various actuators of the engine 10. For example, adjusting the flow of compressed air from the electric turbocharger 159 can include adjusting an actuator (e.g., an electric motor 159) of the compressor 174 to adjust the output of the compressor 174 (e.g., the amount of compressed intake air flowing from the compressor 174 to the engine cylinders). Further examples are described below with reference to FIGS. 2-4. Figures 4 to 6 The controller 12 receives signals from various sensors of the engine 10 and, based on the received signals and instructions stored in the memory of the controller, adjusts engine operation with various actuators of the engine 10. For example, adjusting the flow of compressed air from the electric turbocharger 159 can include adjusting an actuator (e.g., an electric motor 159) of the compressor 174 to adjust the output of the compressor 174 (e.g., the amount of compressed intake air flowing from the compressor 174 to the engine cylinders). Further examples are described below with reference to FIGS. 2-4. The controller 12 receives signals from various sensors of the engine 10 and, based on the received signals and instructions stored in the memory of the controller, adjusts engine operation with various actuators of the engine 10. For example, adjusting the flow of compressed air from the electric turbocharger 159 can include adjusting an actuator (e.g., an electric motor 159) of the compressor 174 to adjust the output of the compressor 174 (e.g., the amount of compressed intake air flowing from the compressor 174 to the engine cylinders). Further examples are described below with reference to FIGS. 2-4.

[0033] As described above, Figure 1 Only one cylinder of the multi-cylinder engine is shown. Thus, each cylinder can similarly include its own set of intake / exhaust valves, one or more fuel injectors, spark plug, etc. It will be appreciated that the engine 10 can include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Moreover, each of these cylinders can include any suitable number of intake / exhaust valves, fuel injectors, spark plugs, etc. Figure 1 Some or all of the various components described and depicted with reference to the cylinder 14.

[0034] In some examples, the vehicle 5 can be a hybrid vehicle having multiple torque sources available to one or more wheels 55. In other examples, the vehicle 5 is a conventional vehicle having only an engine, or an electric vehicle having only electric machines. In the illustrated example, the vehicle 5 includes an engine 10 and an electric machine 52. The electric machine 52 can be a motor or a motor / generator (M / G). When one or more clutches 56 are engaged, the crankshaft 140 of the engine 10 and the electric machine 52 are connected to the wheels 55 via a transmission 54. In the depicted example, a first clutch 56 is disposed between the crankshaft 140 and the electric machine 52, while a second clutch 56 is disposed between the electric machine 52 and the transmission 54. The controller 12 can send signals to actuators of each clutch 56 to cause the clutch to engage or disengage in order to connect or disconnect the crankshaft 140 and the electric machine 52, and components connected thereto, and / or to connect or disconnect the electric machine 52 and the transmission 54, and components connected thereto. The transmission 54 can be a gearbox, a planetary gear system, or another type of transmission. The powertrain can be configured in various ways, including parallel, series, or series-parallel hybrid vehicles.

[0035] The electric machine 52 receives electrical power from a power battery 58 to provide torque to the wheels 55. The electric machine 52 can also operate as a generator to provide electrical power to charge the battery 58, for example during a braking operation.

[0036] Figure 2 An engine system 200 is schematically illustrated, which includes an engine 295 similar to the engine 10 described above with reference to Figure 1 The engine system 200 includes several components similar to those described above with reference to Figure 1 For example, the engine system 200 includes an intake passage 220 having a compressor 294 coupled to an electric motor 293, a turbocharger 285 having a turbine 288 coupled to the compressor 294 via a shaft 292, a throttle valve 230, an exhaust passage 283, and an emission control device 284, similar to the intake passage 142 having the compressor 174 coupled to the electric motor 175, the turbocharger 159 having the turbine 176 coupled to the compressor 174 via the shaft 180, the throttle valve 162, the exhaust passage 148, and the emission control device 178 described above with reference to Figure 1 For example, the engine system 200 includes an intake passage 220 having a compressor 294 coupled to an electric motor 293, a turbocharger 285 having a turbine 288 coupled to the compressor 294 via a shaft 292, a throttle valve 230, an exhaust passage 283, and an emission control device 284, similar to the intake passage 142 having the compressor 174 coupled to the electric motor 175, the turbocharger 159 having the turbine 176 coupled to the compressor 174 via the shaft 180, the throttle valve 162, the exhaust passage 148, and the emission control device 178 described above with reference to

[0037] Further, the engine system 200 includes a plurality of cylinders similar to the cylinders 14 described above with reference to Figure 1 For example, the engine system 200 includes an intake passage 220 having a compressor 294 coupled to an electric motor 293, a turbocharger 285 having a turbine 288 coupled to the compressor 294 via a shaft 292, a throttle valve 230, an exhaust passage 283, and an emission control device 284, similar to the intake passage 142 having the compressor 174 coupled to the electric motor 175, the turbocharger 159 having the turbine 176 coupled to the compressor 174 via the shaft 180, the throttle valve 162, the exhaust passage 148, and the emission control device 178 described above with reference to Figure 2The example shown is disposed within the cylinder head 209. Specifically, the engine 295 of the engine system 200 includes a first cylinder 202, a second cylinder 208, and a third cylinder 214. The first cylinder 202 includes a first intake valve 223, a first exhaust valve 217, a first fuel injector 271, and a first spark plug 277, the second cylinder 208 includes a second intake valve 225, a second exhaust valve 219, a second fuel injector 273, and a second spark plug 279, and the third cylinder 214 includes a third intake valve 227, a third exhaust valve 221, a third fuel injector 275, and a third spark plug 281. Each of the intake valves (e.g., the intake valves 223, 225, and 227) can be similar to the intake valve 150, each of the exhaust valves (e.g., the exhaust valves 217, 219, and 221) can be similar to the exhaust valve 156, each of the fuel injectors (e.g., the fuel injectors 271, 273, and 275) can be similar to the fuel injector 166, and each of the spark plugs (e.g., the spark plugs 277, 279, and 281) can be similar to the spark plug 192, where the intake valve 150, the exhaust valve 156, the fuel injector 166, and the spark plug 192 are described above with reference to FIG. 1. Figure 1 The example shown includes three cylinders of the engine 295, but in other examples, the engine 295 can include a different number of cylinders (e.g., four, six, eight, ten, twelve, etc.), where each cylinder includes a respective intake valve, exhaust valve, fuel injector, and spark plug. In some examples, each cylinder can include more than one intake valve and / or exhaust valve (e.g., two intake valves and two exhaust valves per cylinder). Figure 2 The example shown includes three cylinders of the engine 295, but in other examples, the engine 295 can include a different number of cylinders (e.g., four, six, eight, ten, twelve, etc.), where each cylinder includes a respective intake valve, exhaust valve, fuel injector, and spark plug. In some examples, each cylinder can include more than one intake valve and / or exhaust valve (e.g., two intake valves and two exhaust valves per cylinder).

[0038] The engine system 200 can additionally include one or more heat exchangers (e.g., the radiator 264) configured to reduce the temperature of engine coolant (e.g., water) flowing through the cylinder head 209. For example, Figure 2 The radiator 264 is shown coupled to the engine 295 via the first coolant passage 265 and the second coolant passage 260. The radiator 264 can be configured to receive coolant from the cylinder head 209 of the engine 295 via the first coolant passage 265, and can cool the coolant via one or more heat exchange elements (e.g., fins) of the radiator 264. The coolant that has been cooled by the radiator 264 can flow into the cylinder head 209 via the second coolant passage 260, such that the first coolant passage 265 and the second coolant passage 260 form a coolant loop between the radiator 264 and the coolant passage disposed inside the cylinder head 209.

[0039] The engine system 200 can also include a boost passage 296 coupled to the compressor 294 and configured to receive compressed air from the compressor 294, and a bypass passage 224 coupled to the intake passage 220, with the bypass valve 226 located in the bypass passage. The boost passage 296 can additionally include one or more heat exchangers, such as a boost air cooler 298, to reduce the temperature of the compressed air flowing through the boost passage 296 from the compressor 294. In one example, an electronic controller of the engine system 200 (e.g., similar to the controller 12 described above with reference to Figure 1 The controller can increase the opening of the bypass valve 226 to increase the intake airflow from the intake passage 220 through the bypass passage 224 and / or to decrease the intake airflow from the intake passage 220 to the compressor 294. In another example, the controller can decrease the opening of the bypass valve 226 to decrease the intake airflow from the intake passage 220 through the bypass passage 224 and / or to increase the intake airflow from the intake passage 220 to the compressor 294. Increasing and decreasing the opening of the bypass valve 226 via the controller can include transmitting an electrical signal (e.g., an electrical pulse) to the bypass valve 226 to adjust the opening, with one or more parameters of the electrical signal (e.g., amplitude, pulse width, etc.) indicating the desired opening. For example, an electrical signal having a first pulse width that is longer can adjust the bypass valve 226 to a first opening, while an electrical signal having a second width that is shorter can adjust the bypass valve 226 to a second opening, with the first opening being an opening that is greater than the second opening.

[0040] Additionally, the amount of intake air flowing through the boost passage 296 and / or the bypass passage 224 can be adjusted by adjusting the opening of the throttle 230. In one example, the controller can increase or decrease the opening of the throttle 230 by transmitting an electrical signal to an actuator of the throttle 230 to adjust the position of the throttle 230 (e.g., within the intake passage 228) (e.g., similar to the example adjustments described above with reference to the bypass valve 226). The throttle 230 can include a throttle plate and / or a position sensor similar to the throttle plate 164 and the throttle position sensor described above with reference to Figure 1 and the controller can receive a signal from the throttle position sensor to determine the opening of the throttle 230.

[0041] With the throttle 230 in the open position (e.g., a position in which the throttle 230 is not fully closed), intake air can flow through the throttle 230 and into the intake passage 228 fluidly coupled to the intake ports 233, 235, and 237. Each of the intake ports fluidly couples the intake passage 228 to an intake port of an engine cylinder. For example, the intake port 233 fluidly couples the intake passage 228 to the intake port 232 of the first cylinder 202, the intake port 235 fluidly couples the intake passage 228 to the intake port 234 of the second cylinder 208, and the intake port 237 fluidly couples the intake passage 228 to the intake port 236 of the third cylinder 214. Each of the intake ports (e.g., the intake port 232, the intake port 234, and the intake port 236) is sealed by a respective intake valve (e.g., the first intake valve 223, the second intake valve 225, and the third intake valve 227, respectively) during a state in which the respective intake valve is in the fully closed position. The intake ports 233, 235, and 237 can be collectively referred to herein as an intake manifold.

[0042] For example, during a state in which the first intake valve 223 is in the fully closed position, intake air within the intake passage 228 and the intake ports 233, 235, and 237 does not flow through the intake port 232 and into the first cylinder 202. Similarly, during a state in which the second intake valve 225 is in the fully closed position, intake air within the intake passage 228 and the intake ports 233, 235, and 237 does not flow through the intake port 234 and into the second cylinder 208, and during a state in which the third intake valve 227 is in the fully closed position, intake air within the intake passage 228 and the intake ports 233, 235, and 237 does not flow through the intake port 236 and into the third cylinder 214. However, during a state in which the first intake valve 223 is in the open position, intake air within the intake passage 228 and / or the intake ports can flow into the first cylinder 202 via the intake port 232. Similarly, during a state in which the second intake valve 225 is in the open position, intake air can flow into the second cylinder 208 via the intake port 234, and during a state in which the third intake valve 227 is in the open position, intake air can flow into the third cylinder 214 via the intake port 236.

[0043] The intake air within intake passage 228 and intake connectors 233, 235, and 237 can be at different pressures depending on engine operating conditions. For example, during the period when compressor 294 is rotating to compress intake air, the pressure of the compressed intake air is higher than that of atmospheric intake air (e.g., intake air flowing through intake passage 220 and bypass passage 224). In one example, the pressure of the compressed intake air flowing out of compressor 294 could be approximately 2.36 atm, while the pressure of the intake air flowing through passage 220 and bypass passage 224 could be approximately 1 atm. During periods when intake air does not flow into intake passage 228 from bypass passage 224 (e.g., when bypass valve 226 is fully closed), intake air can flow into intake passage 228 only via compressor 294. For example, while the bypass valve is in the fully closed position, intake air flowing through intake passage 220 can be diverted through bypass passage 224 and compressor 294, such that intake air flowing into intake passage 228 is supplied to compressor 294 instead of bypass passage 224. As a result, the pressure of the intake air in intake passage 228 can be higher than atmospheric pressure (e.g., 2.36 atm), and opening one or more of the intake valves (e.g., first intake valve 223) allows pressurized air to flow into the corresponding cylinder (e.g., first cylinder 202) connected to said one or more intake valves.

[0044] The exhaust valves of each cylinder (e.g., the first exhaust valve 217 of the first cylinder 202, the second exhaust valve 219 of the second cylinder 208, and the third exhaust valve 221 of the third cylinder 214) fluidly connect the cylinder to the exhaust passage 283. During the period when the exhaust valves are in the open position (e.g., not fully closed), exhaust gas (e.g., unburned intake air, and / or burned fuel and air) can flow from the cylinder into the exhaust passage 283. For example, during the period when the first exhaust valve 217 is in the open position, exhaust gas can flow out of the first cylinder 202 via the first exhaust passage 259 of the first cylinder 202 and into the exhaust passage 283. During the period when the first exhaust valve 217 is in the fully closed position (e.g., the position where the first exhaust valve 217 abuts against the first exhaust passage 259), the first exhaust valve 217 seals the first exhaust passage 259 so that exhaust gas does not flow from the first cylinder 202 into the exhaust passage 283. Similarly, the second exhaust valve 219 seals the second exhaust passage 261 in a similar manner, while the third exhaust valve 221 seals the third exhaust passage 263 in a similar manner.

[0045] In some examples, such as those mentioned below Figure 5 In the described example, the intake and exhaust valves can each be mechanically actuated (e.g., driven by one or more rotating cams on one or more camshafts of the engine). In other examples, such as those referenced below... Figure 6In the described example, the intake and exhaust valves may be electrically driven (e.g., driven by one or more solenoids, wherein the solenoids are configured to receive electrical signals from a controller to adjust the opening of the intake and exhaust valves) or pneumatically driven (e.g., driven by a pressure-response actuator).

[0046] Exhaust gas can flow from the cylinder through exhaust passage 283 to turbine 288 and turbine bypass passage 278. Turbine bypass passage 282 may include a turbine bypass valve 280 disposed therein, wherein turbine bypass valve 280 is adjustable to different openings (e.g., via an electrical signal transmitted by a controller to an actuator of bypass valve 280 (similar to bypass valve 226 described above)) to control the exhaust gas flow through turbine bypass passage 282. For example, to increase the exhaust gas flow from the cylinder to turbine 288, the controller may transmit an electrical signal (e.g., an electrical pulse) to the actuator of turbine bypass valve 280 to decrease the opening of turbine bypass valve 280. During the state where exhaust gas flows out of the cylinder and through turbine 288, similar to the state described above, the flow is controlled by the turbine bypass valve 278. Figure 1 As illustrated in the example of turbine 176 and compressor 174, compressor 294 can be at least partially powered via turbine 288 through shaft 292. In another example, to reduce exhaust flow from cylinder to turbine 288, the controller can transmit an electrical signal to the actuator of turbine bypass valve 280 to increase the opening of turbine bypass valve 280. Exhaust flowing through turbine bypass valve 280 and / or turbine 288 can flow through exhaust passage 290 to emission control device 284 and out to the atmosphere. Although not described in Figure 2 As shown, but in some examples, engine system 200 may include a low-pressure (LP) or high-pressure (HP) exhaust gas recirculation (EGR) system to recirculate a portion of the exhaust gas flowing out of the cylinder to one or more intake passages (e.g., intake passage 228).

[0047] Figure 3 An engine with three cylinders is shown (as in the reference above). Figure 2 The engine described is 295 and / or the above reference. Figure 1 The cylinder firing order of the engine 10 is described. Figure 3 The ignition timing diagram for each of the three cylinders is depicted. It should be understood that... Figure 3 Cylinders 1, 2, and 3 in the text can correspond to... Figure 2 The diagram shows cylinders 202 (first cylinder), 208 (second cylinder), and 214 (third cylinder). For each diagram, the cylinder number is shown on the y-axis, while the engine stroke is depicted on the x-axis. Furthermore, the ignition and corresponding combustion events within each cylinder are represented by a star symbol between the compression and power strokes within the cylinder. Additionally, supplementary diagram 300 depicts the cylinder ignition events in each cylinder around a circle representing a 720-degree crankshaft rotation.

[0048] In Figure 3 In the example depicted in FIG. 3, the firing and combustion events within the engine and between the three cylinders can occur at intervals of 240 CA (crank angle) degrees. In this context, the firing events can occur at evenly spaced intervals. Likewise, each engine stroke within the three cylinders can occur at intervals of 240 CA degrees. For example, an exhaust stroke in cylinder 1 can be followed by an exhaust stroke in cylinder 2, which can be at approximately 240 CA degrees after the exhaust stroke in cylinder 1. Similarly, after an interval of 240 CA degrees, the exhaust stroke in cylinder 2 can be followed by an exhaust stroke in cylinder 3. The firing events in the engine can occur similarly. An example of a firing order for a three-cylinder engine can be 2-1-3-2-1-3. As shown at 300, cylinder 1 can fire approximately 240 CA degrees after cylinder 2 fires, cylinder 3 can fire approximately 240 CA degrees after the firing event in cylinder 1, and cylinder 2 can fire approximately 240 CA degrees after the firing event in cylinder 3. Thus, a method of operating an engine can include firing a second, a first, and a third cylinder of three cylinders, each firing event separated by 240 degrees of crank angle (CA).

[0049] It should be appreciated that the evenly spaced firing intervals of 240 CA degrees in a three-cylinder engine can be approximate. In one example, the firing interval between cylinder 3 and cylinder 2 can be 230 CA degrees. In another example, the firing interval between cylinder 3 and cylinder 2 can be 255 CA degrees. In yet another example, the firing interval between cylinder 3 and cylinder 2 can be exactly 240 CA degrees. Likewise, the firing interval between cylinder 2 and cylinder 1 can vary in a range between 230 CA degrees and 255 CA degrees. The same variation can apply to the firing interval between cylinder 1 and cylinder 3. Other variations are possible.

[0050] Figure 3 The cylinder configuration and firing order depicted in FIG. 3 describes operation of a three-cylinder engine. In some examples, the firing order can be a different firing order, such as 1-2-3-1-2-3. In another example, the engine can include six cylinders arranged in two rows, with each row having a set of three cylinders (e.g., a V6 engine), where each set of three cylinders has the above-referenced firing order. In this example, the firing order for the engine can be 1-2-3-1-2-3-1-2-3. Figures 2 to 3The same configuration described. In a configuration with two banks of three cylinders each, the firing order can be, for example, 2-5-1-4-3-6, for example, where cylinders 1, 2, and 3 are in one group and cylinders 4, 5, and 6 are in the other group. All of the advantages inherent in the methods described herein for three-cylinder engines also apply to this example of a V6 engine. In yet another example, the engine can have six cylinders arranged in-line (e.g., along a common axis, as an I6 engine) as two groups of three cylinders each, where each group of three cylinders has the same configuration described above with reference to Figures 2 to 3 The same configuration described. In this configuration, the firing order can be 2-5-1-4-3-6, where cylinders 1, 2, and 3 are in one group and cylinders 4, 5, and 6 are in the other group. All of the advantages inherent in the methods described herein for three-cylinder engines (and six-cylinder V6 engines) also apply to I6 engines. In yet another example, the engine can have twelve cylinders arranged in two banks of six cylinders each (e.g., a V12 engine), where each bank of six cylinders has the same configuration described in the discussion of the I6 engine above (e.g., each bank of six cylinders includes two groups of three cylinders each, and each group of three cylinders has the same configuration described above with reference to Figures 2 to 3 The same configuration described. In this configuration, the firing order can be 2-5-1-4-3-6, where cylinders 1, 2, and 3 are in one group and cylinders 4, 5, and 6 are in the other group. All of the advantages inherent in the methods described herein for three-cylinder engines (and six-cylinder V6 engines) also apply to I6 engines. In yet another example, the engine can have twelve cylinders arranged in two banks of six cylinders each (e.g., a V12 engine), where each bank of six cylinders has the same configuration described in the discussion of the I6 engine above (e.g., each bank of six cylinders includes two groups of three cylinders each, and each group of three cylinders has the same configuration described above with reference to

[0051] Figure 4 A method 400 for controlling an electric turbocharger of an engine to start the engine is shown. In some examples, the electric turbocharger and engine can be the electric turbocharger 159 and engine 10 described above with reference to Figure 1 The electric turbocharger 285 and engine 295 described above with reference to Figure 2 The electric turbocharger 285 and engine 295 described above with reference to Figure 3 The firing order shown and described above. However, the firing order shown by Figure 3 The firing order shown and described above. However, the firing order shown by Figure 3 The firing order shown and described above. However, the firing order shown by Figure 3The illustrated method can be applied to engines having different numbers of cylinders (e.g., four, eight, etc.) and / or cylinder arrangements (e.g., in-line arrangements, multi-bank cylinders, etc.) as described above. Instructions for performing the method 400, as well as the remainder of the methods included herein, can be executed by a controller (e.g., by the controller 12 illustrated and described above). Figure 1 The controller 12 illustrated and described above) based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference to Figure 1 The controller can adjust engine operation using engine actuators of the engine system in accordance with the methods described below.

[0052] At 402, the method includes estimating and / or measuring engine operating conditions. For example, the engine operating conditions can include engine speed, engine torque output, engine coolant temperature, vehicle speed, spark timing, barometric pressure, boost flow and / or boost pressure, fuel injection amount, crankshaft position, etc. The controller can estimate and / or measure the engine operating conditions based on signals transmitted to the controller by one or more sensors of the engine system. For example, the controller can receive a signal (e.g., an electrical signal) from a crankshaft position sensor (e.g., the Hall effect sensor 120 illustrated by Figure 1 and other types of sensors) in order to estimate and / or measure a position of the crankshaft (e.g., an amount of rotation of the crankshaft relative to a reference or initial position). In another example, the controller can receive a signal (e.g., an electrical signal) from an absolute manifold pressure sensor (e.g., the sensor 124 illustrated by Figure 1 in order to estimate and / or measure an absolute intake manifold pressure. In yet another example, the controller can receive a signal from one or more mass air flow sensors (e.g., the mass air flow sensor 122 illustrated by Figure 1 upstream and / or downstream of a compressor of an electric turbocharger (e.g., the compressor 174 illustrated by Figure 2 or the compressor 294 illustrated by Figure 1 in order to measure and / or estimate an amount of compressed air (from the compressor) and / or an amount of un-compressed air (from a bypass passage, such as the bypass passage 224 illustrated by Figure 2 to the engine cylinders (e.g., the first cylinder 202, the second cylinder 208, and / or the third cylinder 214 illustrated by Figure 2 .

[0053] At 404, the method includes determining whether the engine is operating. In one example, determining whether the engine is operating can be based on the estimated and / or measured engine operating conditions at 402. For example, the controller can determine whether the engine is operating based on a signal received from a sensor of the engine (e.g., the sensor 126 illustrated by Figure 1The control signal transmitted to the controller from the described sensors) to determine whether the engine is operating. In one example, the controller can determine whether the engine is operating based on the estimated and / or measured engine speed, engine torque output, vehicle speed, spark timing, fuel injection amount, and / or engine coolant temperature. For example, during a condition in which fuel is not injected into the engine cylinders and / or the engine is not producing torque, the controller can determine that the engine is not operating (e.g., fuel / air is not combusting within the engine cylinders). In another example, during a condition in which fuel is injected into the engine cylinders via one or more fuel injectors and the engine is producing torque, the controller can determine that the engine is operating (e.g., the engine is combusting fuel / air within the engine cylinders).

[0054] In some examples, the controller can also estimate and / or determine a duration of operation of the engine. For example, in one example, the controller can determine how long the engine has been operating since a most recent engine start request. In another example, the controller can determine how long the engine has not been operating since a most recent engine off event. During a condition in which the controller determines that the engine is not operating (e.g., the engine is in a non-operating mode and is not combusting fuel / air as described above), the controller can estimate a duration of the non-operating mode based on the engine coolant temperature (e.g., as indicated by a signal transmitted to the controller from one or more engine coolant temperature sensors) and / or other estimated and / or measured engine parameters (e.g., operating conditions). During a condition in which the controller determines that the engine is operating (e.g., the engine is in an operating mode in which fuel / air is combusting within the engine cylinders as described above), the controller can estimate a duration of time that the engine has been operating based on the engine coolant temperature and / or other estimated and / or measured engine parameters. In yet other examples, the controller can determine a duration of engine operation or non-operation based on information (e.g., data) stored in a memory (e.g., a non-transitory computer memory) of the controller. For example, during a condition in which the engine transitions from an operating mode to a non-operating mode, the controller can store information in the memory of the controller indicating a duration of the operating mode. Similarly, during a condition in which the engine transitions from a non-operating mode to an operating mode, the controller can store information in the memory of the controller indicating a duration of the non-operating mode.

[0055] If the controller determines at 404 that the engine is operating, the method proceeds in response thereto to 406, where the method includes maintaining engine operating conditions. For example, if the engine is operating at 404, at 406 the controller can maintain the speed, torque output, fuel injection rate, and / or other engine operating parameters (e.g., the controller can not adjust the engine operating parameters).

[0056] However, if the controller determines at 404 that the engine is not in operation (e.g., the engine is in a non-operating mode), the method proceeds to 408 in response, whereby the method includes determining whether an engine start operation is requested. In one example, the engine start request may be in response to an ignition start event or an optional vehicle start event. As another example, in an engine equipped with a start-stop button, the engine start request may be in response to the operator of the engine (e.g., the driver of the vehicle including the engine) pressing the start-stop button.

[0057] If no engine start request is indicated at 408, the method continues to 406 in response to this (e.g., in response to the lack of an engine start request), wherein the method includes maintaining engine operating conditions. For example, if no engine start request is indicated at 408, at 406, the controller may maintain the engine in a non-operating mode (e.g., the controller does not inject fuel into the engine cylinders and / or does not initiate sparks in the engine cylinders).

[0058] However, if an engine start request is indicated at 408, the method continues to 410 in response to this (e.g., in response to and during the engine start request), whereby the method includes determining the piston position of each cylinder. In one example, the controller may be based on data from one or more crankshaft position sensors (e.g., by...). Figure 1 The signal (e.g., an electrical signal) transmitted from the Hall effect sensor 120 (shown and described above) to the controller determines the piston position of each cylinder. For example, during a recent engine shutdown event (e.g., an engine shutdown event prior to the determination at 410), the controller can receive electrical signals from one or more crankshaft position sensors and can estimate and / or measure the amount of crankshaft rotation relative to a reference point. In one example, the reference point may correspond to 0° crankshaft rotation, and the controller can determine the amount of crankshaft rotation relative to the reference point (e.g., 240° relative to the reference point, 300° relative to the reference point, etc.) based on the signals transmitted to the controller from one or more crankshaft position sensors.

[0059] In addition, the controller can receive signals from one or more crankshaft position sensors indicating the full number of crankshaft revolutions during the most recent duration of engine operation, in order to determine the engine's firing order (e.g., as...). Figure 3 The ignition sequence shown and described above determines the piston position of each cylinder. For example, the controller at 410 can determine the position of the piston in the first cylinder of the engine (e.g., the one set by the ignition sequence). Figure 2The piston in the first cylinder 202 (as shown and described above) is positioned between the top dead center (TDC) and bottom dead center (BDC) positions, and the stroke associated with the position of the piston in the first cylinder can also be determined. For example, the controller can determine that further rotation of the crankshaft causes the piston in the first cylinder to move toward the TDC position. Similarly, the controller at 410 can determine the position of the second cylinder (e.g., the one provided by the engine) in the engine. Figure 2 As shown and as described above, the piston in the second cylinder 208 is positioned between TDC and BDC, and the controller can also determine that the rotation of the crankshaft causes the piston in the second cylinder to move toward the BDC position. The controller can perform a similar determination for each cylinder of the engine (e.g., for each piston located in each cylinder of the engine).

[0060] In response to determining the piston position of each cylinder at 410 as described above, the method continues from 410 to 412, wherein the method includes activating an electric turbocharger coupled to the engine's intake system to increase the intake pressure above a threshold pressure. (Referring to the above...) Figure 1 The electric turbocharger 159 shown is composed of... Figure 2 As shown in the electric turbocharger 285, the electric turbocharger includes an electric motor (e.g., electric motor 175 of electric turbocharger 159, or electric motor 293 of electric turbocharger 285), which is configured to drive the compressor of the electric turbocharger (e.g., compressor 174 of electric turbocharger 159 or compressor 294 of electric turbocharger 285) in response to excitation of the electric motor. Specifically, the electric motor is configured to be energized (e.g., by electricity via one or more power sources of the engine, such as those from...) Figure 1The battery 58) shown and described above directs the electric motor) to turn the compressor of the electric turbocharger during the state. In one example, the electric motor can turn the compressor in response to a control signal transmitted to the motor by the controller. In some examples, the electric motor can be a non-variable speed electric motor that is adjustable between an ON mode (e.g., a mode in which the electric motor turns the compressor of the electric turbocharger) and an OFF mode (e.g., a mode in which the electric motor does not turn the compressor of the electric turbocharger), where the adjustment between the ON mode and the OFF mode occurs in response to a control signal transmitted to the electric motor by the controller. In another example, the electric motor can be a variable speed electric motor that is configured to turn the compressor of the electric turbocharger at different speeds in response to different levels of excitation of the electric motor. For example, the electric motor can be a direct current (DC) electric motor, where the speed at which the electric motor turns the compressor is responsive to the voltage supplied to the electric motor. In one example, the electric motor can turn the compressor at a lower first speed (e.g., 5,000 revolutions per minute) in response to a lower first voltage (e.g., 120 volts) supplied to the electric motor, and the electric motor can turn the compressor at a higher second speed (e.g., 10,000 revolutions per minute) in response to a higher second voltage (e.g., 240 volts) supplied to the electric motor.

[0061] At 412, the electric motor is excited (as described above) to turn the compressor of the electric turbocharger to increase the intake air pressure above the threshold pressure. For example, the electric motor can be adjusted from the OFF mode to the ON mode to increase the intake air pressure within the intake system above the threshold pressure. In one example, the threshold pressure can be 2.36 atm. In some examples, at 412, the throttle of the engine (e.g., the throttle 230 by Figure 2 shown or the throttle 162 by Figure 1 shown) can be in a fully closed position and can increase the intake air pressure upstream of the throttle (e.g., within the boost passage 296 by Figure 2 shown and described above). In other examples, the throttle of the engine can be in a partially open position or a fully open position and can increase the intake air pressure downstream of the throttle (e.g., at the intake manifold) above the threshold pressure.

[0062] In response to the energizing of the electrically powered turbocharger at 412, optionally from 412 proceeds to 414, where the method includes adjusting the position of one or more intake valves and / or exhaust valves of the engine. In some examples, adjusting the position of the one or more intake valves and / or exhaust valves occurs at 414 concurrently with or during the energizing of the electrically powered turbocharger at 412. In one example, adjusting the position of the one or more intake valves and / or exhaust valves can occur prior to the intake pressure exceeding the threshold pressure. For example, the engine can be configured to include electrically or pneumatically actuated intake valves and / or exhaust valves such that the position of the intake valves and / or exhaust valves can be adjusted in response to a signal (e.g., an electrical signal) transmitted by the controller to an actuator of the intake valves and / or exhaust valves. In one example, each of the intake valves (e.g., the first intake valve 223, the second intake valve 225, and the third intake valve 227) can be electrically or pneumatically actuated valves, and each of the exhaust valves (e.g., the first exhaust valve 217, the second exhaust valve 219, and the third exhaust valve 221) can be electrically or pneumatically actuated valves. At 414, the controller can transmit an electrical signal to the actuators of the intake valves and / or exhaust valves in order to adjust the opening of the intake valves and / or exhaust valves. For example, at 414, one or more of the intake valves can be moved from a partially closed or fully closed position to a fully open position, and / or one or more of the exhaust valves can be moved from a partially closed or fully closed position to a fully open position. Similarly, one or more of the intake valves can be moved from a partially open or fully open position to a fully closed position, and / or one or more of the exhaust valves can be moved from a partially open or fully open position to a fully closed position.

[0063] In some examples, the controller can determine which intake valves and which exhaust valves to adjust based on the determined piston position of each cylinder (e.g., the piston position determined at 410). For example, with respect to the engine 295 shown in FIG. 2A and described above, at 410 the controller can determine that the piston disposed within the second cylinder 208 is at the TDC position such that rotation of the crankshaft of the engine moves the piston disposed within the second cylinder 208 toward the BDC position. Further, the controller can determine that the pistons disposed within the first cylinder 202 and the third cylinder 214 are at positions between the TDC position and the BDC position such that rotation of the crankshaft moves the piston disposed within the first cylinder 202 toward the BDC position and rotation of the crankshaft moves the piston disposed within the third cylinder 214 toward the TDC position. The controller can determine the relative motion of the pistons in response to the rotation of the crankshaft based on a predetermined firing order (e.g., a firing timing) of the cylinders stored in a non-transitory memory of the controller (e.g., the firing order shown in FIG. 2B and described above). Figure 2 Figure 3 With respect to the engine 295 shown in FIG. 2A and described above, at 410 the controller can determine that the piston disposed within the second cylinder 208 is at the TDC position such that rotation of the crankshaft of the engine moves the piston disposed within the second cylinder 208 toward the BDC position. Further, the controller can determine that the pistons disposed within the first cylinder 202 and the third cylinder 214 are at positions between the TDC position and the BDC position such that rotation of the crankshaft moves the piston disposed within the first cylinder 202 toward the BDC position and rotation of the crankshaft moves the piston disposed within the third cylinder 214 toward the TDC position. The controller can determine the relative motion of the pistons in response to the rotation of the crankshaft based on a predetermined firing order (e.g., a firing timing) of the cylinders stored in a non-transitory memory of the controller (e.g., the firing order shown in FIG. 2B and described above).

[0064] ​At 410, the controller can determine which pistons are positioned closest to the TDC position and are configured to move toward the BDC position in response to positive rotation of the crankshaft (e.g., rotation of the crankshaft in the normal crankshaft drive direction during engine operation). The controller can then fully open the intake valves coupled to the cylinder including the piston positioned closest to the TDC position and configured to move toward the BDC position at 414. For example, the engine can include only three cylinders, and a single cylinder (e.g., the second cylinder 208) of the engine can include a piston positioned closer to the TDC than each other piston of each other cylinder, where the piston of the single cylinder is configured to move toward the BDC in response to positive rotation of the crankshaft. The controller can fully open the intake valves coupled to the single cylinder at 414, and can not open the intake valves coupled to each other cylinder.

[0065] In another example, the engine can include only six cylinders, and two cylinders of the engine can include pistons having the same relative piston position, where the pistons of the two cylinders are positioned closer to the TDC than each other piston of each other cylinder, and where the pistons of the two cylinders are configured to move toward the BDC in response to positive rotation of the crankshaft. The controller can fully open the intake valves coupled to the two cylinders at 414, and can not adjust the intake valves coupled to each other cylinder. Other examples are possible for engines including different numbers (e.g., eight) of cylinders, where the controller opens the intake valves of the cylinders including the pistons positioned closest to the TDC and configured to move toward the BDC, and the controller does not adjust the intake valves of each other cylinder. The cylinders whose intake valves move to the fully open position at 414 can be referred to herein collectively as a first cylinder group. For example, the cylinders of the first cylinder group include a first plurality of intake valves and a first plurality of exhaust valves, where each intake valve of the first plurality of intake valves is in an open position (e.g., a fully open position) and each exhaust valve of the first plurality of exhaust valves is in a fully closed position.

[0066] Further, the controller can adjust the position of one or more exhaust valves of the engine at 414. Specifically, the exhaust valves coupled to each cylinder of the first cylinder group can not be adjusted at 414. However, the exhaust valves coupled to each other cylinder (e.g., cylinders not included in the first cylinder group) can be moved to a fully open position at 414. The cylinders whose exhaust valves are moved to the fully open position at 414 are collectively referred to herein as a second cylinder group, where the second cylinder group is different from the first cylinder group. For example, while the pressurized air is flowing into the cylinders of the first cylinder group to drive the crankshaft (as described below with reference to 416), the pressure of the gases within the cylinders of the second cylinder group can be maintained at atmospheric pressure due to the second plurality of intake valves each being in a fully closed position and the second plurality of exhaust valves each being in an open position (e.g., adjusted to the fully open position at 414), where the second plurality of intake valves and the second plurality of exhaust valves are included in the cylinders of the second cylinder group.

[0067] By adjusting the intake valves of the first cylinder group to the fully open position and the exhaust valves of the second cylinder group to the fully open position at 414, the cylinders that include pistons not moving toward the BDC position (e.g., the cylinders within the second cylinder group) can be maintained at atmospheric pressure (e.g., via the trapped gases being vented to the atmosphere through exhaust passages (such as exhaust passage 283 shown in FIG. 2 and described above)). Figure 2 Further, the cylinders that include pistons moving toward the BDC position (e.g., the cylinders within the first cylinder group) have their intake valves open so as to fluidly couple the cylinders to one or more intake passages of the engine (e.g., intake passage 228 shown in FIG. 2 and described above). Figure 2

[0068] In examples of engines that do not include electrically or pneumatically actuated intake and exhaust valves (e.g., engines that include mechanically actuated valves (such as valves that open and close via rotation of cams of one or more camshafts)), the method can not include 414. Instead, the method can continue from 412 to 416.

[0069] At 416, the method includes initiating rotation of the crankshaft by flowing pressurized intake air to the cylinders of the engine to drive the pistons disposed within the cylinders via only the pressurized intake air for a period of time. In some examples, flowing the pressurized intake air to the cylinders of the engine occurs at or during 412 while the electric turbocharger is energized and / or at or during 414 while the one or more intake and / or exhaust valves are adjusted. In one example, the position of the one or more intake and / or exhaust valves can be adjusted prior to flowing the pressurized intake air to the cylinders of the engine. For example, at 412, the intake ports of each cylinder (e.g., intake ports 226 shown in FIG. 2 and described above) can be adjusted to the fully open position. Figure 2 ​The intake pressure at the intake port 232 (and the intake ports 233, 235, and 237 shown and described above) can be increased above the threshold pressure. However, at 412, one or more intake valves of the cylinders (e.g., the first intake valve 223, the second intake valve 225, and / or the third intake valve 227) can be in a fully closed position (e.g., the intake valves coupled to the cylinders of the second cylinder group). The cylinders including the intake valves that are fully closed during the energizing of the electric motor at 412 are unable to receive the pressurized intake air flowing from the compressor. For example, with respect to the application of 412 to the intake port 233, the first intake valve 223, and the intake passage 228 coupled to the first cylinder 202 by the intake port 232 shown and described above, the first intake valve 223 can be in a fully closed position at 412. As a result, at 412, the intake air within the intake port 233 can be pressurized above the threshold pressure, but the pressurized intake air does not flow into the first cylinder 202 (e.g., does not flow through the intake port 232 and around the first intake valve 223). Figure 2 The method of fluidly coupling the first cylinder 202 to the intake passage 228 by the intake port 232 shown and described above, at 412, the first intake valve 223 can be in a fully closed position. As a result, at 412, the intake air within the intake port 233 can be pressurized above the threshold pressure, but the pressurized intake air does not flow into the first cylinder 202 (e.g., does not flow through the intake port 232 and around the first intake valve 223).

[0070] The flowing of the pressurized intake air to the engine cylinders at 416 can increase the intake pressure within the cylinders in order to drive the pistons disposed within the cylinders. Specifically, at 416, the fuel / air is not combusting within the engine cylinders, and the pistons disposed within the cylinders are driven solely by the pressurized intake air flowing into the cylinders.

[0071] With respect to engines including electrically or pneumatically actuated intake and exhaust valves, pressurized air can flow into the cylinders of the first cylinder group (e.g., cylinders having intake valves in the fully open position) in order to drive the pistons disposed within the cylinders of the first cylinder group and rotate the crankshaft of the engine (e.g., drive the pistons disposed within the cylinders of the first cylinder group toward the bottom dead center position). By opening the exhaust valves of the cylinders of the second cylinder group at 414, the magnitude of the force used to drive the pistons of the first cylinder group can be reduced. For example, as described above, opening the exhaust valves of the cylinders of the second cylinder group maintains the cylinders of the second cylinder group at atmospheric pressure (e.g., when the pistons disposed within the cylinders of the second cylinder group are driven toward the top dead center position). When pressurized air flows into the cylinders of the first cylinder group, the pistons disposed within the cylinders of the first cylinder group can be driven by the pressurized air to drive the crankshaft of the engine without additional resistance from compression of air within the cylinders of the second cylinder group. In this way, the pistons can be driven with a reduced amount of pressurized air and / or a reduced pressure of the pressurized air, resulting in a reduced response time of the engine (e.g., a reduced amount of time to initiate rotation of the crankshaft) and a reduced amount of electrical energy consumed to energize the electric motor of the electrically driven turbocharger (e.g., to increase intake pressure above a threshold pressure). In some examples, with respect to engines including electrically or pneumatically actuated intake and exhaust valves adjusted as described above at 414, the threshold pressure described at 412 can be reduced. For example, for such engines, the threshold pressure can be less than 2.36 atm (e.g., 2 atm).

[0072] With respect to engines including mechanically actuated intake and exhaust valves (e.g., valves actuated via contact with rotating cams of one or more camshafts), the positions of the intake and exhaust valves can not be adjusted at 414. As a result, the pressurized intake air flowing to the engine cylinders at 416 enters the cylinders with the intake valves in a partially open or fully open position. In one example, the intake valves can be in a partially open or fully open position due to the position (e.g., amount of rotation) of the crankshaft at the most recent engine stop event (e.g., an event in which the engine transitions from operating to non-operating, such as in response to engine shutdown). In some examples, in response to an engine stop event, the controller can adjust the firing timing (e.g., spark timing and / or fuel injection timing) during the engine stop so as to position the crankshaft at a particular amount of rotation (e.g., 120 degrees of rotation relative to a reference point described above) after the engine stop. For example, prior to running the method 400 (e.g., prior to an engine start request and in response to an engine stop event immediately prior to the engine start request, where no other engine stop events or engine start requests are between the engine stop event and the engine start request), the crankshaft can be rotated to a position in which one or more of the pistons of the engine are at TDC, with the intake valves of the respective cylinders including the pistons in a fully open position. In this configuration, when pressurized intake air flows to the cylinders at 416, the pressurized air can flow into the cylinders with the intake valves in a fully open position so as to more easily drive the pistons disposed within the cylinders from the TDC position to the BDC position and rotate the crankshaft.

[0073] The pressurized intake air can flow to the cylinders at 416 for a duration so as to rotate the crankshaft more than a threshold number of complete revolutions and / or rotate the crankshaft at a speed greater than a threshold speed. For example, with respect to engines including electrically or pneumatically actuated intake and exhaust valves, the pressurized air can be delivered to the cylinders when the controller adjusts the openings of the intake and exhaust valves so as to enable the intake pressure to drive the pistons via rotation of the crankshaft and generate torque. In one example, the threshold number of complete crankshaft revolutions can be two, corresponding to 720 degrees of crank rotation, such that the duration spans at least 720 degrees of crank rotation. In other examples, the threshold number of complete crankshaft revolutions can be a different number (e.g., four). In another example, the threshold speed of the crankshaft can be 75 revolutions per minute. The intake and exhaust valves can be opened and closed by the controller throughout the duration so as to enable the pistons to be driven by the pressurized air while increasing the amount of force applied to the crankshaft. For example, during a state in which the pistons are moving from the BDC position toward the TDC position, the exhaust valves of the cylinders including the pistons can be opened by the controller so as to reduce the amount of gas compressed by the pistons, thereby enabling the pressurized air to be delivered to the cylinders with the intake valves open to more effectively drive the pistons and crankshaft. One example of intake and exhaust valve adjustments within the duration described with reference to 416 is described byFigure 6 is shown and described below.

[0074] With respect to engines that include mechanically actuated intake and exhaust valves, pressurized air can flow into the engine cylinders according to predetermined intake valve opening sequences throughout the duration. For example, because the intake and exhaust valves are driven via rotation of cams coupled to one or more rotatable camshafts, the relative intake valve timing (e.g., intake valve opening and closing timing) and exhaust valve timing (e.g., exhaust valve opening and closing timing) are predetermined according to the shape, size, relative position, etc. of the cams. As a result, the intake valve timing and exhaust valve timing can not be adjustable via a controller. Accordingly, throughout the duration described with reference to 416 (e.g., pressurized intake air flow to the cylinders to rotate the crankshaft a threshold number of revolutions and / or to rotate the crankshaft above a threshold speed), the intake and exhaust valves of an engine that does not include electrically or pneumatically actuated valves can open and close according to predetermined valve timing (determined by the shape, size, relative position, etc. of the cams coupled to the one or more rotatable camshafts, as shown and described below with reference to 420). The predetermined valve timing can be stored in the non-transitory memory of the controller. Figure 5

[0075] The method continues from 416 to 418, where the method includes initiating combustion of fuel and air within an engine cylinder. In one example, the controller can transmit a signal (e.g., an electrical signal) to one or more spark plugs disposed within a cylinder of the engine in order to initiate combustion of fuel and air within the engine cylinder. The fuel can be injected into the engine cylinder via one or more fuel injectors (e.g., fuel injectors 166 shown by Figure 1 Figure 2 Figure 3 The controller at 418 enables the engine to transition from a mode in which the pistons are driven by pressurized intake air only (and fuel and air are not combusting within the engine cylinders) (which can be referred to herein as a start-up mode or a transition mode) to an operational mode in which fuel and air are combusting within the engine cylinders.

[0076] Figure 4 ​​​​In the example of the method 400 shown and as described herein, the engine can be in an inoperative state in which fuel and air are not combusting within the engine cylinders and the pistons are not being driven by pressurized air. An operator of the engine (e.g., a driver of a vehicle including the engine) can initiate a fire event in order to indicate to the controller a request for engine startup. During the engine startup request, the controller can determine the piston position of each cylinder as described at 410, and can energize the electric turbocharger in order to increase intake pressure above a threshold pressure as described at 412. The engine can include electrically or pneumatically actuated intake and exhaust valves, and the controller can adjust the position of the intake and exhaust valves at 414 in order to reduce the amount of force (e.g., pressure from the pressurized intake air) required to drive the pistons of the engine with the pressurized intake air during the engine startup request. During the engine startup request, pressurized intake air flows to the cylinders at 416 and pressurizes one or more of the cylinders in order to drive the pistons disposed in the cylinders and rotate the crankshaft without combusting fuel and air. Once the crankshaft has rotated a threshold number of revolutions and / or has exceeded a threshold rotational speed, the controller initiates combustion of fuel and air within the engine cylinders in order to generate an increased amount of torque via the crankshaft (e.g., to operate the crankshaft in an operational mode in which fuel and air are combusting within the engine cylinders according to a predetermined firing timing of the engine, where the predetermined firing timing is stored in a non-transitory memory of the controller).

[0077] In some examples, the method optionally continues from 418 to 420, where the method includes reducing the engine rotational speed via one or more deceleration procedures. For example, due to the delivery of compressed intake air to the engine cylinders to drive the pistons and crankshaft for a period of time prior to combustion of fuel and air within the engine cylinders, the engine can be operating at a relatively high boost level when the controller initiates combustion of fuel and air within the engine cylinders at 418. In order to reduce the amount of torque output by the engine during the initial combustion of fuel and air, the controller can adjust various engine parameters via one or more deceleration procedures stored in a non-transitory memory of the controller in order to reduce the magnitude of the increase in engine rotational speed provided by the relatively high boost level. In one example, the controller can transmit a signal (e.g., an electrical signal) to a bypass valve (e.g., the bypass valve 226 described above) in order to increase the opening of the bypass valve (e.g., an electric turbocharger bypass valve) and reduce the amount of compressed air flowing into the engine. In another example, for an engine including electrically or pneumatically actuated intake and exhaust valves, the controller can adjust the opening time of one or more of the intake and / or exhaust valves in order to temporarily reduce the torque output of the engine. In yet another example, the controller can adjust the firing timing of one or more cylinders in order to reduce the amount of work (e.g., engine torque) produced by the combusting fuel and air within the one or more cylinders. Other examples are also possible. Figure 2 In some examples, the method optionally continues from 418 to 420, where the method includes reducing the engine rotational speed via one or more deceleration procedures. For example, due to the delivery of compressed intake air to the engine cylinders to drive the pistons and crankshaft for a period of time prior to combustion of fuel and air within the engine cylinders, the engine can be operating at a relatively high boost level when the controller initiates combustion of fuel and air within the engine cylinders at 418. In order to reduce the amount of torque output by the engine during the initial combustion of fuel and air, the controller can adjust various engine parameters via one or more deceleration procedures stored in a non-transitory memory of the controller in order to reduce the magnitude of the increase in engine rotational speed provided by the relatively high boost level. In one example, the controller can transmit a signal (e.g., an electrical signal) to a bypass valve (e.g., the bypass valve 226 described above) in order to increase the opening of the bypass valve (e.g., an electric turbocharger bypass valve) and reduce the amount of compressed air flowing into the engine. In another example, for an engine including electrically or pneumatically actuated intake and exhaust valves, the controller can adjust the opening time of one or more of the intake and / or exhaust valves in order to temporarily reduce the torque output of the engine. In yet another example, the controller can adjust the firing timing of one or more cylinders in order to reduce the amount of work (e.g., engine torque) produced by the combusting fuel and air within the one or more cylinders. Other examples are also possible.

[0078] In some examples, the determination of the piston position of each cylinder occurs simultaneously with or during the activation of the electric turbocharger (e.g., the electric motor that activates the electric turbocharger) to increase the intake pressure above a threshold pressure, and the activation of the electric turbocharger occurs simultaneously with and / or during the adjustment of the positions of one or more intake valves and / or exhaust valves. Furthermore, instructions stored in the controller's memory may include determining whether an engine start request is made, and in response to an engine start request, increasing the intake pressure above a threshold pressure via instructions to send signals (e.g., electrical signals) to the actuators of the electric motor of the electric turbocharger, adjusting the positions of one or more intake valves and / or exhaust valves via instructions to send signals to the actuators of one or more intake valves and / or exhaust valves, and / or directing pressurized intake airflow into the engine cylinders via instructions to send signals to the actuators of one or more valves (e.g., throttle valves or bypass valves) to adjust the valve positions. Additionally, instructions stored in the controller's memory may include determining whether an engine start request is not made, and in response, maintaining engine operation as described above. In some examples, the method may include determining whether to perform one or more of the following based on whether the engine is operating and whether an engine start request is requested (e.g., present): increasing intake pressure, adjusting the position of one or more valves, and / or allowing pressurized intake air to flow into the engine cylinders.

[0079] Turn now Figure 5 A graph 500 is shown illustrating engine parameters such as piston position, intake valve lift (e.g., intake valve opening), exhaust valve lift (e.g., exhaust valve opening), etc. In one example, such as... Figure 5 The engine parameters shown can be derived from... Figure 2 The parameters of engine 295 shown and as described above, or those derived from... Figure 1 The parameters of engine 10 are shown and described above. (By...) Figure 5 The engine parameters shown correspond to engines that do not include electrically or pneumatically actuated intake and exhaust valves. For example, as mentioned above, the engine's intake and exhaust valves can be mechanically actuated (e.g., cam-driven).

[0080] Figure 5 The curve shows the electric turbocharger excitation (e.g., the excitation of electric motor 175 or electric motor 293) at curve 506 and the turbocharger speed (e.g., the speed of turbocharger 159 or turbocharger 285) at curve 508. Figure 5Additionally shown is spark timing (e.g., ignition timing) for each cylinder, including spark timing for the first cylinder at curve 510 (e.g., spark timing for the first spark plug 277 of the first cylinder 202), spark timing for the second cylinder at curve 512 (e.g., spark timing for the second spark plug 279 of the second cylinder 208), and spark timing for the third cylinder at curve 514 (e.g., spark timing for the third spark plug 281 of the third cylinder 214). Fuel injection rates for the cylinders are included, with fuel injection rates at the first cylinder shown at curve 516 (e.g., fuel injection rate for the first fuel injector 277), fuel injection rates at the second cylinder shown at curve 518 (e.g., fuel injection rate for the second fuel injector 279), and fuel injection rates at the third cylinder shown at curve 520 (e.g., fuel injection rate for the third fuel injector 281). Cylinder pressure (e.g., cylinder gas pressure) within the first cylinder is shown at curve 522, cylinder pressure within the second cylinder is shown at curve 524, and cylinder pressure within the third cylinder is shown at curve 526. Atmospheric pressure is indicated at 546, and a first threshold pressure (e.g., the threshold pressure described above at 412) is indicated at 548. Piston position within the first cylinder is shown at curve 528, piston position within the second cylinder is shown at curve 530, and piston position within the third cylinder is shown at curve 532. Intake valve lift for an intake valve (e.g., the first intake valve 223) coupled to the first cylinder is shown at curve 534, intake valve lift for an intake valve (e.g., the second intake valve 225) coupled to the second cylinder is shown at curve 536, and intake valve lift for an intake valve (e.g., the third intake valve 227) coupled to the third cylinder is shown at curve 538. Exhaust valve lift for an exhaust valve (e.g., the first exhaust valve 217) coupled to the first cylinder is shown at curve 540, exhaust valve lift for an exhaust valve (e.g., the second exhaust valve 219) coupled to the second cylinder is shown at curve 542, and exhaust valve lift for an exhaust valve (e.g., the third exhaust valve 221) coupled to the third cylinder is shown at curve 544.

[0081] At time to, the engine is not operating (e.g., fuel and air are not combusting within the engine cylinders, and the engine is not producing torque). At time ti, in response to an engine start request (e.g., as described above with reference to 408), the electric turbocharger is energized as shown by curve 506 and as described above with reference to 412. Between times ti to t2, the speed of the electric turbocharger increases as shown by curve 508.

[0082] The increase in speed of the turbocharger corresponds to rotation of the compressor of the electrically variable geometry turbocharger (e.g., via the electric motor of the electrically variable geometry turbocharger) to increase intake air pressure within the intake system. In one example, at time t2, the throttle of the engine can move to a fully open position (e.g., as described above) to cause pressurized intake air to flow to the engine cylinders. Because the intake valve of the first cylinder is in an open position at time t2 (e.g., as indicated by curve 534), pressurized intake air flows to the first cylinder (e.g., as described above with reference to 416) and begins to drive the piston disposed within the first cylinder (e.g., as indicated by curve 528). As the piston of the first cylinder is driven by the pressurized intake air, the crankshaft of the engine rotates by the piston movement, thereby causing each piston to move relative to each other piston. In some examples, the opening time of each intake valve can overlap with the opening time of one or more other intake valves. For example, the intake valve lift of the intake valve of the first cylinder indicated by curve 534 can slightly overlap with the intake valve lift of the intake valve of the second cylinder indicated by curve 536 and / or the intake valve lift of the intake valve of the third cylinder indicated by curve 538.

[0083] Between times t2 and t4, as pressurized intake air flows into the first cylinder via the open intake valve of the first cylinder (indicated by curve 534), the piston disposed within the first cylinder is driven toward the BDC position (as indicated by curve 528), the piston disposed within the third cylinder is driven from the BDC position toward the TDC position by rotation of the crankshaft (e.g., via the piston disposed within the first cylinder being driven by the pressurized air). The intake valve of the third cylinder then moves from the fully closed position toward the fully open position (as indicated by curve 538), and pressurized intake air flows into the third cylinder to drive the piston disposed within the third cylinder from the TDC position toward the BDC position to further rotate the crankshaft. Similarly, as the piston disposed within the third cylinder is driven toward the BDC position by pressurized intake air, the piston disposed within the second cylinder is moved from the BDC position toward the TDC position by rotation of the crankshaft (e.g., via the piston disposed within the third cylinder being driven by the pressurized air). The intake valve of the second cylinder moves from the fully closed position toward the fully open position (as indicated by curve 536), and pressurized intake air flows into the second cylinder to drive the piston disposed within the second cylinder from the TDC position toward the BDC position to further rotate the crankshaft.

[0084] At time t3, fuel is injected into the second cylinder during the opening of the intake valve of the second cylinder as indicated by curve 518. The crankshaft continues to rotate, and at time t5, a spark is initiated in the second cylinder as indicated by curve 512. After time t5, the combusted fuel and air drive the crankshaft in accordance with the predetermined firing timing of the engine (e.g., as described above with reference to 410) stored in the non-transitory memory of the controller. Figure 3 The described firing timing). The combusted fuel and air drive the crankshaft.

[0085] Turning now to Figure 6 , a graph 600 is shown that illustrates engine parameters, such as piston position, intake valve lift (e.g., intake valve opening), exhaust valve lift (e.g., exhaust valve opening), etc. In one example, the engine parameters shown can be parameters of the engine 295 shown and described above or parameters of the engine 10 shown and described above. The engine parameters shown correspond to an engine that includes electrically or pneumatically actuated intake and exhaust valves. For example, as described above, the intake and exhaust valves can be opened and / or closed in response to control signals transmitted by the controller to actuators of the valves. Figure 6 Figure 6 Figure 2 Figure 1

[0086] Figure 6 A graph 606 is shown that illustrates electric turbocharger excitation (e.g., excitation of the electric motor 175 or the electric motor 293) and a graph 608 is shown that illustrates turbocharger speed (e.g., speed of the turbocharger 159 or the turbocharger 285). Figure 6 ​​​​Additionally shown is the spark timing (e.g., the ignition timing) of each cylinder, including the spark timing of the first cylinder at curve 610 (e.g., the spark timing of the first spark plug 277 of the first cylinder 202), the spark timing of the second cylinder at curve 612 (e.g., the spark timing of the second spark plug 279 of the second cylinder 208), and the spark timing of the third cylinder at curve 614 (e.g., the spark timing of the third spark plug 281 of the third cylinder 214). Included is the fuel injection rate of the cylinder, with the fuel injection rate at the first cylinder shown at curve 616 (e.g., the fuel injection rate of the first fuel injector 277), the fuel injection rate at the second cylinder shown at curve 618 (e.g., the fuel injection rate of the second fuel injector 279), and the fuel injection rate at the third cylinder shown at curve 620 (e.g., the fuel injection rate of the third fuel injector 281). Shown at curve 622 is the cylinder pressure (e.g., the cylinder gas pressure) within the first cylinder, at curve 624 is the cylinder pressure within the second cylinder, and at curve 626 is the cylinder pressure within the third cylinder. Indicated at 646 is the atmospheric pressure, and at 648 is the first threshold pressure (e.g., the threshold pressure described above at 412). Shown at curve 628 is the piston position within the first cylinder, at curve 630 is the piston position within the second cylinder, and at curve 632 is the piston position within the third cylinder. Shown at curve 634 is the intake valve lift of the intake valve (e.g., the first intake valve 223) coupled to the first cylinder, at curve 636 is the intake valve lift of the intake valve (e.g., the second intake valve 225) coupled to the second cylinder, and at curve 638 is the intake valve lift of the intake valve (e.g., the third intake valve 227) coupled to the third cylinder. Shown at curve 640 is the exhaust valve lift of the exhaust valve (e.g., the first exhaust valve 217) coupled to the first cylinder, at curve 642 is the exhaust valve lift of the exhaust valve (e.g., the second exhaust valve 219) coupled to the second cylinder, and at curve 644 is the exhaust valve lift of the exhaust valve (e.g., the third exhaust valve 221) coupled to the third cylinder.

[0087] At time tO, the engine is not operating (e.g., fuel and air are not combusting within the engine cylinders, and the engine is not producing torque). At time ti, in response to an engine start request (e.g., as described above with reference to 408), the electric turbocharger is energized as shown by curve 606 and as described above with reference to 412. Between times ti to t2, the speed of the electric turbocharger increases as shown by curve 608. Additionally, because the engine includes electrically or pneumatically actuated intake and exhaust valves, at time ti, the controller transmits a signal (e.g., an electrical signal) to the actuators of the exhaust valves of the second and third cylinders (indicated by curves 642 and 644, respectively) in order to move the exhaust valves of the second and third cylinders to the fully open position. As a result of the exhaust valves being in the fully open position, the pressure within the second and third cylinders can decrease to atmospheric pressure (as described above with reference to 414), such that the pistons disposed within the first cylinder can be driven with reduced force. Figure 4

[0088] The increase in the speed of the turbocharger corresponds to the rotation of the compressor of the electric turbocharger (e.g., via the electric motor of the electric turbocharger) in order to increase the intake air pressure within the intake system. In one example, at time t2, the intake valve of the first cylinder is moved to the fully open position (e.g., indicated by curve 634) in order to allow pressurized intake air to flow into the first cylinder. The pressurized intake air flows into the first cylinder (e.g., as described above with reference to 416) and begins to drive the piston disposed within the first cylinder (e.g., shown by curve 628). As the piston of the first cylinder is driven by the pressurized intake air, the crankshaft of the engine rotates by the movement of the piston, thereby moving each piston relative to each other piston. In some examples, the opening time of each intake valve can overlap with the opening time of one or more other intake valves. For example, the intake valve lift of the intake valve of the first cylinder indicated by curve 634 can slightly overlap with the intake valve lift of the intake valve of the second cylinder indicated by curve 636 and / or the intake valve lift of the intake valve of the third cylinder indicated by curve 638.

[0089] ​Between times t2 and t4, as each piston is driven from the TDC position toward the BDC position, the intake valve associated with each cylinder is moved to the fully open position to enable pressurized intake air to flow into the cylinder. For example, at time t2, the intake valve of the first cylinder is moved to the fully open position (indicated by curve 634) to enable intake air to flow into the first cylinder to drive the first piston (and rotate the crankshaft of the engine). Rotation of the crankshaft causes the second piston to move toward the TDC position (indicated by curve 630), and as the second piston moves from the TDC position toward the BDC position, the intake valve of the second cylinder is fully opened (indicated by curve 636) to enable pressurized intake air to flow into the second cylinder to drive the second piston. Similarly, after the second piston moves from TDC, rotation of the crankshaft moves the third piston to TDC, and the intake valve of the third cylinder is opened to enable pressurized intake air to drive the third piston from TDC to BDC.

[0090] As each piston moves from BDC to TDC between times t2 and t3, the exhaust valve coupled to each respective cylinder is opened to enable the crankshaft to more easily rotate. For example, as the first piston is driven from BDC to TDC, the exhaust valve of the first cylinder, which includes the first piston, is fully opened to reduce the pressure (e.g., gas pressure) within the first cylinder so that the first cylinder piston can more easily move toward TDC (e.g., without compressing the gas within the first cylinder). The exhaust valves of each of the other cylinders operate in a similar manner.

[0091] In this configuration, actuation of the intake and exhaust valves by the controller enables the rotation of the crankshaft to quickly accelerate due to the pistons being driven by pressurized intake air.

[0092] At time t3, when the intake valve of the second cylinder is in the fully open position, fuel is injected into the second cylinder, indicated by curve 618. The crankshaft continues to rotate, and at time t5, a spark is initiated in the second cylinder, as indicated by curve 612. After time t5, the combusting fuel and air drive the crankshaft, in accordance with the predetermined firing timing of the engine (e.g., the firing timing described above with reference to FIG. 6A). Figure 3

[0093] ​In the above-described configuration, pressurized air from the compressor of the electric turbocharger drives pistons of the engine to rotate a crankshaft of the engine prior to combustion of fuel and air within the engine cylinders in response to a request to start the engine. By driving the pistons via pressurized air alone, the engine can be started without additional components such as a dedicated starter motor. Additionally, the electric turbocharger can include a turbine that is driven by exhaust gas during normal engine operation (e.g., during a state in which the engine is driven by combustion of fuel and air). By reducing the number of components required to start the engine (e.g., by starting the engine via the electric turbocharger without a separate starter motor), the cost and / or maintenance time of the engine can be reduced.

[0094] In this way, by starting the engine via the electric turbocharger according to the above-described method, the engine can be started without a starter motor (e.g., a separate motor configured to turn a starting or rotating crankshaft via a mechanical coupling (such as a belt) between the starter motor and the crankshaft during engine start-up). By starting the engine via the electric turbocharger, the engine can be configured without a starter motor, thereby reducing the weight and cost of the engine. Moreover, turning the compressor of the electric turbocharger during engine start-up can result in a faster response time for delivering boost (e.g., compressed air) to the engine after engine start-up. As a result, engine performance and efficiency can be improved.

[0095] The technical effect of flowing compressed intake air to the engine cylinders during a request to start the engine is to drive pistons of the engine to rotate a crankshaft of the engine prior to combustion of fuel and air within the engine cylinders.

[0096] In one embodiment, a method for an engine includes, during an engine start request, driving a crankshaft of the engine without combustion by only flowing compressed air from an electric air compressor to cylinders of the engine and without actuating a starter motor coupled to the crankshaft. In a first example of the method, the electric air compressor is part of an electric turbocharger, and flowing the compressed air out of the electric turbocharger includes energizing an electric motor of the electric turbocharger to turn an air compressor of the electric turbocharger in response to the engine start request. A second example of the method optionally includes the first example, and further includes where the electric air compressor is part of the electric turbocharger, and flowing the compressed air out of the electric turbocharger includes increasing a pressure of the compressed air above a threshold pressure by turning the air compressor of the electric turbocharger. A third example of the method optionally includes one or both of the first and second examples, and further includes where the threshold pressure is greater than 2 atm. A fourth example of the method optionally includes one or more or each of the first through third examples, and further includes where the pressure of the compressed air is first increased above the threshold pressure within an intake passage upstream of a throttle valve of the engine; then, the throttle valve is opened to flow the compressed air to the cylinders. A fifth example of the method optionally includes one or more or each of the first through fourth examples, and further includes where the pressure of the compressed air is first increased above the threshold pressure at an intake manifold of the engine; then, an intake valve of the cylinders is adjusted from a fully closed position to an open position to flow the compressed air to the cylinders. A sixth example of the method optionally includes one or more or each of the first through fifth examples, and further includes determining a position of each piston disposed within each of the cylinders, and adjusting the intake valve based on the determined position of each piston. A seventh example of the method optionally includes one or more or each of the first through sixth examples, and further includes, after a period of time of driving the crankshaft without combustion by only flowing compressed air from the electric air compressor to the engine cylinders and without actuating the starter motor, injecting fuel into the cylinders and combusting the fuel and compressed air within the cylinders. An eighth example of the method optionally includes one or more or each of the first through seventh examples, and further includes where the duration is based on a rotational speed of the crankshaft exceeding a threshold rotational speed. A ninth example of the method optionally includes one or more or each of the first through eighth examples, and further includes where the duration is based on a number of complete rotations of the crankshaft exceeding a threshold number of complete rotations after the engine start request.A tenth example of the method may optionally include one or more of the first to ninth examples, and further includes wherein fuel and air are not burned in the cylinder during the entire duration in which the crankshaft is driven solely by allowing compressed air to flow from the electric turbocharger to the cylinder. An eleventh example of the method may optionally include one or more of the first to tenth examples, and further includes reducing the engine speed after the duration via a deceleration program stored in a non-transient memory of the engine's electronic controller. A twelfth example of the method may optionally include one or more of the first to eleventh examples, and further includes wherein the deceleration program includes one of the following: increasing the opening of a bypass valve of the electric turbocharger connected in parallel with the air compressor, adjusting the opening time of the intake and / or exhaust valves of the cylinder, or adjusting the ignition timing of the cylinder.

[0097] In another embodiment, a method for an engine includes: in response to an engine start request, causing compressed intake air to flow from a compressor of an electric turbocharger to an engine cylinder, and driving a piston disposed within the engine cylinder solely via the compressed intake air for a period of time, wherein the opening of an intake valve and an exhaust valve coupled to the engine cylinder are adjusted via a camshaft throughout the duration; and after the duration, switching from driving the piston solely via the compressed intake air to driving the piston via combustion of fuel and air by initiating combustion within the engine cylinder. In a first example of the method, the method further includes adjusting the ignition timing of the engine to position a first piston at top dead center at the time of engine stop, prior to the engine start request and in response to an engine stop event immediately preceding the engine start request, wherein there are no other engine stop events or engine start requests between the engine stop event and the engine start request. A second example of the method optionally includes the first example and further includes the duration spanning at least 720 degrees of crankshaft rotation.

[0098] In another embodiment, a method for an engine includes: in response to an engine start request: allowing compressed air to flow into cylinders of a first cylinder bank to drive the crankshaft of the engine solely via the compressed air, the cylinders of the first cylinder bank including a first plurality of intake valves and a first plurality of exhaust valves, wherein each of the first plurality of intake valves is in an open position and each of the first plurality of exhaust valves is in a fully closed position; and maintaining gas pressure in cylinders of a second cylinder bank at atmospheric pressure while allowing compressed air to flow into the cylinders of the first cylinder bank to drive the crankshaft, the cylinders of the second cylinder bank including a second plurality of intake valves and a second plurality of exhaust valves, wherein each of the second plurality of intake valves is in a fully closed position and each of the second plurality of exhaust valves is in an open position. In a first example of the method, the method further includes: increasing the opening of the first plurality of intake valves via an electronic controller of the engine before allowing compressed air to flow into the cylinders of the first cylinder bank to drive the crankshaft and during the engine start request. A second example of the method optionally includes the first example, and further includes: increasing the opening of the exhaust valves in the second plurality of exhaust valves via an electronic controller of the engine before allowing compressed air to flow into the cylinders of the first cylinder bank to drive the crankshaft and during the engine start request. A third example of the method optionally includes one or both of the first and second examples, and further includes: in response to the engine start request, allowing compressed air to flow into the cylinders of the first cylinder bank to drive a piston disposed in the cylinders of the first cylinder bank toward the bottom dead center position and a piston disposed in the cylinders of the second cylinder bank toward the top dead center position, wherein when the piston disposed in the cylinders of the second cylinder bank is driven toward the top dead center position, the gas pressure in the cylinders of the second cylinder bank is maintained at atmospheric pressure.

[0099] In another representation, a method for an engine for a hybrid electric vehicle (HEV) includes: during an engine start request, driving the crankshaft of the engine solely by causing compressed air to flow from an electric turbocharger to the cylinders of the engine without combustion and without actuating the starter motor or main electric motor of the HEV.

[0100] Regarding hybrid electric vehicles (HEVs), in some examples, starting the engine via an electric turbocharger can be an auxiliary or backup method of starting the engine, where the primary method involves inducing vehicle motion while the main electric motor (e.g., an electric motor configured to propel the vehicle) powers the vehicle, even when the engine is not supplied with fuel but is engaged (e.g., the crankshaft is rotating). In another example, the main electric motor can power the engine even when the engine's transmission is not engaged with the engine.

[0101] Note that the exemplary control and estimation routines included herein can be used in various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in non-transient 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 can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threaded processing strategies, etc. Therefore, the various actions, operations, and / or functions shown can be executed in the order shown, in parallel, or may be omitted under certain conditions. Similarly, the processing order is not necessarily necessary 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 shown actions, operations, and / or functions can be repeatedly executed according to the specific strategy used. Furthermore, the described actions, operations, and / or functions can be graphically represented as code to be programmed into the non-transient memory of a computer-readable storage medium in the engine control system, wherein the described actions are implemented by executing instructions in conjunction with an electronic controller in a system including various engine hardware components.

[0102] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and these specific embodiments should not be considered limiting, as many variations are possible. For example, the above-described techniques can be applied to V-6, inline 4-cylinder, inline 6-cylinder, V-12, opposed 4-cylinder, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or characteristics.

[0103] The following claims specifically point to certain combinations and sub-combinations that are considered novel and non-obvious. These claims may refer to an element “a” or a “first” element or its equivalent. Such claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or properties may be claimed by amending these claims or by filing new claims in this application or related applications. Such claims, whether broader, narrower, identical, or different in scope from the original claims, are also considered to be included within the subject matter of this disclosure.

[0104] According to the present invention, a method for an engine includes, during an engine start request, driving the crankshaft without combustion solely by causing compressed air to flow from an electric air compressor to the engine cylinder and without actuating a starter motor coupled to the crankshaft of the engine.

[0105] According to an embodiment, the electric air compressor is part of an electric turbocharger, and causing compressed air to flow out of the electric turbocharger includes actuating an electric motor of the electric turbocharger to rotate the air compressor of the electric turbocharger in response to an engine start request.

[0106] According to an embodiment, the electric air compressor is part of the electric turbocharger, and causing compressed air to flow out of the electric turbocharger includes increasing the pressure of the compressed air to above a threshold pressure by rotating the air compressor of the electric turbocharger.

[0107] According to an embodiment, the threshold pressure is greater than 2 atm.

[0108] According to an embodiment, the pressure of the compressed air is first increased to above the threshold pressure in the intake passage upstream of the engine's throttle valve; then, the throttle valve is opened to allow the compressed air to flow into the cylinder.

[0109] According to an embodiment, the pressure of the compressed air is first increased to above the threshold pressure at the intake manifold of the engine; then, the intake valve of the cylinder is adjusted from a fully closed position to an open position to allow the compressed air to flow into the cylinder.

[0110] According to an embodiment, the invention is further characterized by determining the position of each piston disposed in each of the cylinders, and adjusting the intake valve based on the determined position of each piston.

[0111] According to an embodiment, the invention is further characterized in that, without combustion, fuel is injected into the cylinder and the fuel and compressed air are burned in the cylinder after the compressed air flows from the electric air compressor to the engine cylinder and the crankshaft of the engine is driven for a period of time without actuating the starter motor.

[0112] According to an embodiment, the duration is based on the crankshaft speed exceeding a threshold speed.

[0113] According to an embodiment, the duration is based on the crankshaft's full revolutions exceeding a threshold full revolutions after the engine start request.

[0114] According to an embodiment, fuel and air are not burned in the cylinder during the entire duration in which the crankshaft is driven solely by flowing compressed air from the electric turbocharger to the cylinder.

[0115] According to an embodiment, the invention is further characterized in that the engine speed is reduced after the duration via a deceleration program stored in the non-transient memory of the engine's electronic controller.

[0116] According to an embodiment, the deceleration procedure includes one of the following: increasing the opening of the bypass valve of the electric turbocharger connected in parallel with the air compressor, adjusting the opening time of the intake valve and / or exhaust valve of the cylinder, or adjusting the ignition timing of the cylinder.

[0117] According to the present invention, a method for an engine includes: in response to an engine start request, causing compressed intake air to flow from a compressor of an electric turbocharger to an engine cylinder, and driving a piston disposed in the engine cylinder solely via the compressed intake air for a period of time, wherein throughout the duration the opening of an intake valve and an exhaust valve coupled to the engine cylinder are adjusted via a cam of a camshaft; and after the duration the piston is driven from solely via the compressed intake air to via combustion of fuel and air by initiating combustion within the engine cylinder.

[0118] According to one embodiment, the invention is further characterized in that, prior to the engine start request and in response to an engine stop event immediately preceding the engine start request, wherein there are no other engine stop events or engine start requests between the engine stop event and the engine start request, the ignition timing of the engine is adjusted to position the first piston at top dead center when the engine is stopped, wherein the first intake valve coupled to the first cylinder including the first piston is in the fully open position.

[0119] According to an embodiment, the duration spans at least 720 degrees of crankshaft rotation.

[0120] According to the present invention, a method for an engine includes: in response to an engine start request: allowing compressed air to flow into cylinders of a first cylinder bank to drive the crankshaft of the engine solely via the compressed air, the cylinders of the first cylinder bank including a first plurality of intake valves and a first plurality of exhaust valves, wherein each of the first plurality of intake valves is in an open position and each of the first plurality of exhaust valves is in a fully closed position; and maintaining a gas pressure in cylinders of a second cylinder bank at atmospheric pressure while allowing compressed air to flow into the cylinders of the first cylinder bank to drive the crankshaft, the cylinders of the second cylinder bank including a second plurality of intake valves and a second plurality of exhaust valves, wherein each of the second plurality of intake valves is in a fully closed position and each of the second plurality of exhaust valves is in an open position.

[0121] According to an embodiment, the invention is further characterized in that, before compressed air is allowed to flow into the cylinders of the first cylinder bank to drive the crankshaft and during the engine start request, the opening of the intake valves in the first plurality of intake valves is increased via the engine's electronic controller.

[0122] According to an embodiment, the invention is further characterized in that, before compressed air is allowed to flow into the cylinders of the first cylinder bank to drive the crankshaft and during the engine start request, the opening of the exhaust valves in the second plurality of exhaust valves is increased via the engine's electronic controller.

[0123] According to an embodiment, in response to the engine start request, compressed air flows into the cylinder of the first cylinder group to drive the piston disposed in the cylinder of the first cylinder group toward the bottom dead center position and to drive the piston disposed in the cylinder of the second cylinder group toward the top dead center position, wherein when the piston disposed in the cylinder of the second cylinder group is driven toward the top dead center position, the gas pressure in the cylinder of the second cylinder group is maintained at atmospheric pressure.

Claims

1. A method for an engine, comprising: During an engine start request, without combustion, the crankshaft is driven in the normal forward rotational direction simply by allowing compressed air to flow from an electric air compressor to the engine cylinders and without actuating the starter motor coupled to the crankshaft of the engine. The position of each piston in each cylinder is determined, and the corresponding intake valve and exhaust valve are adjusted based on the determined position of each piston, wherein the adjustment includes: moving the intake valve of the first cylinder to the fully open position and putting the exhaust valve of the first cylinder to the fully closed position. And to bring the intake valves of the remaining cylinders to the fully closed position and to move the exhaust valves of the remaining cylinders to the fully open position, wherein the piston of the first cylinder is closer to the top dead center position than the pistons of the remaining cylinders and the piston of the first cylinder moves to the bottom dead center position in response to the forward rotation of the crankshaft.

2. The method of claim 1, wherein the electric air compressor is part of an electric turbocharger, and causing compressed air to flow out of the electric turbocharger includes actuating an electric motor of the electric turbocharger to rotate the electric air compressor of the electric turbocharger in response to the engine start request.

3. The method of claim 2, wherein the electric air compressor is part of the electric turbocharger, and causing compressed air to flow out of the electric turbocharger includes increasing the pressure of the compressed air to above a threshold pressure by rotating the electric air compressor of the electric turbocharger.

4. The method of claim 3, wherein the threshold pressure is greater than 2 atm.

5. The method of claim 3, wherein the pressure of the compressed air is first increased to above the threshold pressure in the intake passage upstream of the throttle valve of the engine; then, the throttle valve is opened to allow the compressed air to flow into the cylinder.

6. The method of claim 3, wherein the pressure of the compressed air is first increased to above the threshold pressure at the intake manifold of the engine; then, the intake valve of the cylinder is adjusted from a fully closed position to an open position to allow the compressed air to flow into the cylinder.

7. The method of claim 2, further comprising: Without combustion, fuel is injected into the cylinder and the fuel and compressed air are burned in the cylinder after the compressed air flows from the electric air compressor to the engine cylinder and the crankshaft of the engine is driven for a period of time without actuating the starter motor.

8. The method of claim 7, wherein the time period is based on the crankshaft speed exceeding a threshold speed.

9. The method of claim 7, wherein the time period is based on the crankshaft's full rotational speed exceeding a threshold full rotational speed after the engine start request.

10. The method of claim 7, wherein fuel and air are not burned in the cylinders during the entire duration of driving the crankshaft solely by causing compressed air to flow from the electric turbocharger to the cylinders.

11. The method of claim 7, further comprising reducing the engine speed after the said time period via a deceleration program stored in a non-transient memory of the electronic controller of the engine.

12. The method of claim 11, wherein the deceleration procedure comprises one of the following: increasing the opening of the bypass valve of the electric turbocharger connected in parallel with the electric air compressor, adjusting the opening time of the intake valve and / or exhaust valve of the cylinder, or adjusting the ignition timing of the cylinder.

13. A system comprising: An engine, which includes multiple cylinders; An electric turbocharger, comprising an electric air compressor adapted to deliver compressed intake air to the plurality of cylinders; and An electronic controller, comprising instructions stored in non-transient computer memory, for: In response to an engine start request, the electric air compressor is actuated to deliver compressed intake air to the plurality of cylinders to drive pistons disposed in the plurality of cylinders in one direction for a period of time only via the compressed intake air, the direction corresponding to the normal forward rotation of the crankshaft coupled to the pistons; The position of each piston in each of the cylinders is determined, and the corresponding intake valve and exhaust valve are adjusted based on the determined position of each piston, wherein the adjustment includes: moving the intake valve of the first cylinder to the fully open position and putting the exhaust valve of the first cylinder to the fully closed position. And to bring the intake valves of the remaining cylinders to the fully closed position and to move the exhaust valves of the remaining cylinders to the fully open position, wherein the piston of the first cylinder is closer to the top dead center position than the pistons of the remaining cylinders and the piston of the first cylinder moves to the bottom dead center position in response to the forward rotation of the crankshaft; and After a certain period of time, by initiating combustion within the engine cylinder, the piston is switched from being driven solely by the compressed intake air to being driven by the combustion of fuel and air.

14. The system of claim 13, wherein the electronic controller further includes instructions stored in a non-transient computer memory for: prior to the engine start request and in response to an engine stop event immediately preceding the engine start request, wherein there are no other engine stop events or engine start requests between the engine stop event and the engine start request, adjusting the ignition timing of the engine to position a first piston in a first cylinder of the plurality of cylinders at top dead center when the engine stops, wherein a first intake valve connected to the first cylinder is in a fully open position.

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