System and method for engine cooling during a start-stop event

Abstract

The present disclosure provides "Systems and methods for engine cooling during a start-stop event." Methods and systems are provided for reducing the temperature of an engine or a single or multiple cylinders of the engine during a start / stop event in which the engine stops burning air and fuel and in response to an overheated engine condition. In one example, a method includes starting an electric air compressor to direct a cooling air flow through a first single cylinder of the engine to reduce the temperature of the first single cylinder to a desired temperature prior to requesting to restart the engine. In this way, a single cylinder indicated as overheated can be effectively cooled without resorting to a method that would otherwise cool the engine as a whole, which can thereby prevent engine degradation and conserve power to an onboard energy storage device.

Description

Technical Field

[0001] The present description generally relates to methods and systems for controlling an electrically driven intake air compressor of a vehicle to cool an overheated vehicle engine.

[0002] Background technology / invention content

[0003] The vehicle may include a coolant system configured to reduce engine overheating by transferring heat to the ambient air. Among them, the coolant circulates through the engine cylinder to remove heat from the hot engine, and the hot coolant is then circulated through a radiator located near the front of the vehicle. The hot coolant may also circulate through a heat exchanger to heat the passenger compartment. The coolant system may include various components, such as various valves, pumps, and one or more thermostats. In the case where the coolant system is degraded due to component failure (e.g., water pump degradation) or due to coolant loss in the cooling system (e.g., due to coolant leakage), the engine may overheat. In turbocharged direct injection engines that tend to run hot due to supercharging and higher loads, engine overheating may be exacerbated.

[0004] Various methods have been developed to address engine overheating in the event of coolant system degradation. One example method shown by Willard et al. in U.S. Pat. No. 9,217,379 addresses engine overheating by alternately shutting off fuel to one or more cylinders while maintaining vehicle torque demand with fueled cylinders. Cylinder cooling is achieved as cool unburned air flows through the unfueled cylinders. In still other methods, cylinder fuel supply may be shut off on a group basis to cool the deactivated groups, while the activated groups continue to generate torque for vehicle propulsion.

[0005] The inventors herein have recognized potential problems with utilizing the above-described approach. As an example, in an engine configured with start-stop (S / S) capability, under-hood temperatures may continue to climb even with all cylinders deactivated. Since the vehicle is stationary and not moving, an idle-stopped engine may continue to overheat even if an additional cooling fan is activated. If the engine is restarted to increase airflow, the fuel economy benefits associated with the start / stop operation may be compromised.

[0006] The inventors herein have developed systems and methods that at least partially address the above-mentioned problems. In one example, a method includes: activating an electric compressor in an air intake of a vehicle engine during a start / stop event in which the engine is not burning air and fuel to direct airflow through a first single cylinder of the engine to reduce the temperature of the first single cylinder to a desired temperature before requesting to restart the engine. In this way, under an S / S event, mitigation actions can be taken for a single cylinder identified as overheating, which can prevent or reduce potential engine degradation from a single overheated cylinder.

[0007] In one example of the method, the method further includes positioning the first single cylinder such that both an intake valve and an exhaust valve of the first single cylinder are in an at least partially open configuration to direct the airflow through the first single cylinder. By positioning the first single cylinder in this manner, the first single cylinder can be effectively cooled during an S / S event.

[0008] The above advantages and other advantages and features of the present specification will be apparent from the following detailed description taken alone or in conjunction with the accompanying drawings.

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

[0010] Figure 1 A vehicle system including an engine system is schematically shown.

[0011] Figure 2 Schematically shown Figure 1 A single cylinder of an engine system.

[0012] Figure 3 A high level exemplary method is shown for selecting whether to conduct individual engine cylinder cooling operation or general engine cooling operation in response to indicating an engine overheat condition.

[0013] Figure 4 Shown for Figure 3 An exemplary method of general engine cooling operation is provided.

[0014] Figure 5 Shown for Figure 3 An exemplary method of single engine cylinder cooling operation.

[0015] Figure 6Describe the use of Figure 5 An exemplary timeline for a single engine cylinder cooling operation is described in detail at .

[0016] Figure 7 Describe the use of Figure 4 An exemplary timeline of general engine cooling operation is described in detail at . DETAILED DESCRIPTION

[0017] The following description relates to systems and methods for reducing the temperature of an engine or one or more engine cylinders under conditions in which the engine or one or more engine cylinders are indicated to be in an overheated state. More particularly, the systems and methods are applicable to reducing the temperature of an engine or one or more cylinders during an S / S event (where the engine is not burning air and fuel, but where the engine temperature may continue to rise if mitigating actions are not taken to prevent this from occurring). Thus, the systems and methods are applicable to vehicles equipped with S / S capabilities, such as in Figure 1 In addition, the systems and methods discussed herein relate to Figure 1 An electric supercharger (also referred to herein as an electric compressor or electric air compressor) positioned upstream of the engine in an engine system shown in FIG. cools the engine and / or cylinders. To perform a single engine cylinder cooling operation, the engine may be controlled so that the cylinder selected for cooling may be positioned so that its intake and exhaust valves are at least partially open, so that pilot air from the electric supercharger may flow through the selected cylinder but may be prevented from flowing through the remaining engine cylinders. Accordingly, Figure 2 Schematic diagram depicting a cylinder equipped with TiVCT (Twin Independent Variable Cam Timing) that can enable this approach. Figure 3 Described is a method for determining whether to perform general engine cooling operation or individual engine cylinder cooling operation depending on whether the engine overheat condition is isolated to a single cylinder or multiple cylinders, or whether the overheat condition is related to the engine system as a whole. Accordingly, Figure 4 An exemplary method for performing general engine cooling operations is depicted, which may include spinning the engine without fuel and directing compressed air through the engine via an electric supercharger to cool the engine. Alternatively, Figure 5 An exemplary method for performing a single engine cooling operation, as described, includes directing compressed air via an electric supercharger through cylinders selected for cooling. Figure 6 Description Figure 5 method, an exemplary timeline for performing a single engine cylinder cooling operation, and Figure 7 Description Figure 4 , an exemplary timeline for performing general engine cooling operations.

[0018] Turning now to the attached drawings, Figure 1 A schematic diagram 101 of a vehicle system 102 is shown, which has an exemplary engine system 100 including an engine 10. The engine 10 includes an engine intake system 162 and an engine exhaust system 163. In one example, the engine system 100 can be a diesel engine system. In another example, the engine system 100 can be a gasoline engine system. In the depicted embodiment, the engine 10 is a supercharged engine coupled to a turbocharger, which includes a compressor 114 driven by a turbine 116. In particular, fresh air is introduced into the engine 10 along the intake passage 42 via an air cleaner 112 and flows to the compressor 114. The compressor can be any suitable intake air compressor, such as a supercharger compressor driven by a motor or a drive shaft. In the engine system 10, the compressor is a turbocharger compressor mechanically coupled to the turbine 116 via a shaft 19, and the turbine 116 is driven by expanding the engine exhaust.

[0019] like Figure 1 As shown, compressor 114 is coupled to throttle 20 via charge air cooler (CAC) 118. Throttle 20 is coupled to engine intake manifold 22. Compressed air charge flows from the compressor through charge air cooler 118 and throttle 20 to intake manifold 22. Figure 1 In the embodiment shown in FIG. 1 , the pressure of the air charge within intake manifold 22 is sensed by manifold air pressure (MAP) sensor 124. In some examples, air flow in the intake manifold may be sensed via mass air flow (MAF) sensor 121. The temperature of ambient air entering intake passage 42 may be estimated via intake air temperature (IAT) sensor 51.

[0020] The engine 10 may include an engine coolant system 185 for engine temperature control which may include various components such as a radiator 186, one or more cooling fans 187, a coolant pump 188, a water pump 189, and a coolant reservoir (or sump) 190. In one example, the CAC 118 may be coupled to the engine coolant system 185, wherein coolant from the engine coolant system 185 may also be circulated through the CAC 118.

[0021] The engine 10 may include one or more engine temperature sensors 181. In one example, the engine temperature sensor 181 may include an engine coolant temperature sensor, wherein the engine temperature is inferred from the engine coolant temperature. In another example, the engine temperature sensor 181 may additionally or alternatively include a cylinder head temperature (CHT) sensor, wherein the engine temperature is inferred from the cylinder head temperature. In other examples, the engine temperature sensor 181 may additionally or alternatively include one or more in-cylinder temperature sensors. For example, for a four-cylinder engine, each of the four cylinders may include an in-cylinder temperature sensor, or any one of the four cylinders may include an in-cylinder temperature sensor.

[0022] One or more sensors may be coupled to the inlet of the compressor 114. For example, a temperature sensor 55 may be coupled to the inlet to estimate the compressor inlet temperature, and a pressure sensor 56 may be coupled to the inlet to estimate the compressor inlet pressure. As another example, an ambient humidity sensor 57 may be coupled to the inlet to estimate the humidity of the air charge entering the intake manifold. Other sensors may, for example, include an air-fuel ratio sensor, etc. In other examples, one or more of the compressor inlet conditions (such as humidity, temperature, pressure, etc.) may be inferred based on the engine operating conditions. In addition, when exhaust gas recirculation (EGR) is enabled (where included), the sensor may estimate the temperature, pressure, humidity, and air-fuel ratio of the air charge mixture including fresh air, recirculated compressed air, and residual exhaust gas received at the compressor inlet.

[0023] In some examples, engine 10 may include one or more knock sensors 131 configured to sense undesirable or unexpected pulses produced by engine detonation. In some examples, data acquired from the one or more knock sensors may be limited to a particular timing window, which may enable determination of which cylinder in the engine is knocking. For example, in some examples, such a determination may be used to infer whether a particular engine cylinder is overheating.

[0024] Wastegate actuator 92 may be actuated to open wastegate 91 to dump at least some exhaust pressure outwardly from upstream of the turbine to a location downstream of the turbine via wastegate 91. By reducing exhaust pressure upstream of the turbine, turbine speed may be reduced, which in turn helps reduce compressor surge. Wastegate 91 may be positioned in wastegate passage 90. The methods discussed herein utilize a wastegate that may be actuated to open and close, however it is recognized herein that in some examples a spring-loaded wastegate may be included in the vehicle system.

[0025] To assist the turbocharger 15, an additional intake air compressor (also referred to herein as an electric supercharger 155) may be incorporated into the vehicle propulsion system. The electric supercharger 155 may be powered via an onboard energy storage device 151, which may include a battery, a capacitor, a supercapacitor, etc. The electric supercharger may include a compressor driven by an electric motor 182. The operating speed of the electric supercharger may include adjusting the operating speed of the electric motor, which is operated via the onboard energy storage device 151.

[0026] The energy storage device 151 may periodically receive electrical energy from a power source 191 that is external to the vehicle (e.g., not part of the vehicle), as indicated by arrow 192. As a non-limiting example, the vehicle system 102 may be configured as a plug-in hybrid electric vehicle (HEV), in which electrical energy may be supplied to the energy storage device 151 from the power source 191 via an electrical energy transmission cable 193. During operation of recharging the energy storage device 151 from the power source 191, the electrical transmission cable 193 may electrically couple the energy storage device 151 and the power source 191. When the vehicle propulsion system is operated to propel the vehicle, the electrical transmission cable 193 may disconnect the connection between the power source 191 and the energy storage device 151. The control system 14 may identify and / or control the amount of electrical energy stored at the energy storage device, which may be referred to as a state of charge (SOC). As noted, in some examples, the traction battery 58 may also obtain electrical energy from the power source 191. Furthermore, in some examples, the traction battery 58 and the energy storage device 151 may include the same energy storage device.

[0027] In other examples, electrical transmission cable 193 may be omitted, where electrical energy may be wirelessly received at energy storage device 151 from power source 191. For example, energy storage device 151 may receive electrical energy from power source 191 via one or more of electromagnetic induction, radio waves, and electromagnetic resonance. Thus, it should be appreciated that any suitable method may be used to recharge energy storage device 151 from a power source that is not part of the vehicle.

[0028] In one example, the electric supercharger 155 may be actuated in response to a demand for increased wheel torque so as to quickly provide the desired boost air to the engine when the turbocharger turbine accelerates. Thus, the increased torque may be met without inducing turbo hysteresis, which may have otherwise occurred if assistance from the electric supercharger is not available. In such an example, in response to the turbocharger accelerating to a threshold speed (e.g., 70,000 rpm), the electric supercharger 155 may be stopped from actuating or deactivating. More specifically, the operational control of the electric supercharger 155 may be implemented based on a command signal (e.g., a duty cycle or pulse width signal) received from a vehicle controller (e.g., controller 12). For example, the controller may send a signal to the electric supercharger actuator 155b, which may actuate the electric supercharger. In another example, the controller may send a signal to the electric supercharger actuator 155b, which may stop actuating the electric supercharger. In one example, an electric supercharger actuator may include an electric motor that drives compressed air.

[0029] The electric supercharger 155 may be positioned between a first electric supercharger conduit 159a and a second electric supercharger conduit 159b. The first electric supercharger conduit 159a may fluidly couple the intake passage 42 to the electric supercharger 155 upstream of the electric supercharger bypass valve 161. The second electric supercharger conduit 159b may fluidly couple the electric supercharger 155 to the intake passage 42 downstream of the electric supercharger bypass valve 161. As an example, air may be drawn into the electric supercharger 155 via the first electric supercharger conduit 159a upstream of the electric supercharger bypass valve 161, and the compressed air may exit the electric supercharger 155 and be directed to the intake passage 42 via the second electric supercharger conduit downstream of the electric supercharger bypass valve 161. In this way, the compressed air may be directed to the engine air intake 22.

[0030] In the event that the electric supercharger 155 is activated to provide boost more quickly than if relying solely on the turbocharger 15, it will be appreciated that the electric supercharger bypass valve 161 may be commanded closed when the electric supercharger 155 is activated. In this way, intake air may flow through the turbocharger 15 and through the electric supercharger 155. Once the turbocharger reaches a threshold speed, the electric supercharger 155 may be disconnected and the electric supercharger bypass valve 161 may be commanded open.

[0031] Intake manifold 22 is coupled to a series of combustion chambers 30 via a series of intake valves (not shown). The combustion chambers are further coupled to exhaust manifold 36 via a series of exhaust valves (not shown). In the depicted embodiment, a single exhaust manifold 36 is shown. However, in other embodiments, the exhaust manifold may include multiple exhaust manifold sections. A configuration with multiple exhaust manifold sections may enable outflows from different combustion chambers to be directed to different locations in the engine system.

[0032] In one embodiment, each of the exhaust valve and the intake valve may be electronically actuated or controlled. In another embodiment, each of the exhaust valve and the intake valve may be cam actuated or controlled. Whether electronically actuated or cam actuated, the timing of the opening and closing of the exhaust valve and the intake valve can be adjusted as needed for the desired combustion and emission control performance. Although a camshaft is not shown in this exemplary schematic, one or more camshaft position sensors 199 may be included in the vehicle propulsion system. In addition, the crankshaft 174 may include a crankshaft position sensor 197. In some examples, one or both of the crankshaft position sensor 197 and / or the camshaft position sensor 199 can be used to infer the position of one or more pistons coupled to the combustion chamber 30.

[0033] Combustion chamber 30 may be supplied with one or more fuels such as gasoline, an ethanol fuel blend, diesel, biodiesel, compressed natural gas, etc. via injector 66. Fuel may be supplied to the combustion chamber via direct injection, port injection, throttle body injection, or any combination thereof. Combustion may be initiated in the combustion chamber via an ignition spark and / or compression ignition.

[0034] like Figure 1 As shown, exhaust gas from one or more exhaust manifold sections may be directed to turbine 116 to drive the turbine. The combined flow from the turbine and the wastegate then flows through emission control device 170. In one example, emission control device 170 may be a light-off catalyst. Typically, exhaust aftertreatment device 170 is configured to catalytically treat the exhaust flow and thereby reduce the amount of one or more substances in the exhaust flow. For example, exhaust aftertreatment device 170 may be configured to trap NO from the exhaust flow when the exhaust flow is lean. x , and reduce the trapped NO when the exhaust gas flow is concentrated x In other examples, exhaust aftertreatment device 170 may be configured to reduce NO x Disproportionate or selective reduction of NO xIn other examples, exhaust aftertreatment device 170 may be configured to oxidize residual hydrocarbons and / or carbon monoxide in the exhaust flow. Different exhaust aftertreatment catalysts having any such functions may be arranged separately or together in the wash coat or elsewhere in the exhaust aftertreatment stage. In some embodiments, the exhaust aftertreatment stage may include a regenerable soot filter configured to trap and oxidize soot particles in the exhaust flow.

[0035] In some examples, engine exhaust system 163 may further include a gasoline particulate filter (GPF) 164. GPF 164 may include a particulate filter, a hydrocarbon trap, a catalytic washcoat, or a combination thereof. In some examples, during operation of engine 10, GPF 164 may be periodically regenerated by operating at least one cylinder of the engine within a particular air-fuel ratio to increase the temperature of GPF 164 so that retained hydrocarbons and soot may be oxidized.

[0036] In some examples, temperature sensor 166 may be positioned upstream of the inlet of GPF 217, and temperature sensor 167 may be positioned downstream of GPF 164. For example, temperature sensors 166 and 167 may be used to estimate the temperature of GPF 164 for regeneration purposes. Additionally, pressure in the exhaust system may be estimated by pressure sensor 165. For example, pressure sensor 165 may be a differential pressure sensor positioned upstream (closer to the exhaust manifold) and downstream (further away from the exhaust manifold) of GPF 164. Pressure sensor 165 may be used to determine the pressure at the inlet of GPF 164 in order to estimate the operating conditions for air introduced into the inlet of GPF 164 for regeneration. Additionally, in some examples, a soot sensor may be positioned downstream of GPF 164 to estimate the level of soot released from GPF 164.

[0037] In some examples, an exhaust gas recirculation (EGR) delivery passage 180 may be coupled to exhaust passage 104 upstream of turbine 116 to provide high pressure EGR (HP-EGR) to the engine intake manifold downstream of compressor 114. EGR valve 152 may be coupled to EGR passage 180 at the junction of EGR passage 180 and intake passage 42. EGR valve 152 may be opened to permit a controlled amount of exhaust gas to enter the compressor outlet for achieving desired combustion and emission control performance. EGR valve 152 may be configured as a continuously variable valve or an on / off valve. In further embodiments, the engine system may include a low pressure EGR (LP-EGR) flow path, in which exhaust gas is drawn from downstream of turbine 116 and recirculated to the engine intake manifold upstream of compressor 114.

[0038] One or more sensors may be coupled to the EGR passage 180 for providing details about the composition and condition of the EGR. For example, a temperature sensor 168 may be provided for determining the temperature of the EGR, a pressure sensor 169 may be provided for determining the pressure of the EGR, a humidity sensor (not shown) may be provided for determining the humidity or water content of the EGR, and an air-fuel ratio sensor (not shown) may be provided for estimating the air-fuel ratio of the EGR. Alternatively, the EGR state may be inferred by one or more temperature sensors, pressure sensors, humidity sensors, and air-fuel ratio sensors coupled to the compressor inlet.

[0039] A number of sensors including an exhaust temperature sensor 128, an exhaust oxygen sensor (e.g., 126), an exhaust flow sensor, and an exhaust pressure sensor 129 may be coupled to the primary exhaust passage 104. The oxygen sensor may be a linear oxygen sensor or UEGO (universal or wide range exhaust gas oxygen sensor), a two-state oxygen sensor or EGO, HEGO (heated EGO), NOx, HC, or CO sensor.

[0040] The engine system 100 may also include a control system 14. The control system 14 is shown as receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 18 (various examples of which are described herein). As an example, the sensors 16 may include an exhaust gas sensor 126 located upstream of the turbine 116, a MAP sensor 124, an exhaust gas temperature sensor 128, an exhaust gas pressure sensor 129, a compressor inlet temperature sensor 55, a compressor inlet pressure sensor 56, an ambient humidity sensor 57, an IAT sensor 51, an engine coolant temperature sensor (e.g., 181), etc. Other sensors (such as additional pressure, temperature, air / fuel ratio, and composition sensors) may be coupled to various locations in the engine system 100. In addition, sensors coupled to the exterior of the vehicle system (such as a rain sensor (windshield sensor) 130) may be used to estimate ambient humidity.

[0041] The actuators 18 may include, for example, an electric supercharger bypass valve 161, a throttle valve 20, an electric supercharger actuator 155b, an EGR valve 152, a wastegate 92, a throttle valve 20, and a fuel injector 66. The control system 14 may include a controller 12. The controller 12 may receive input data from various sensors, process the input data, and trigger various actuators in response to the processed input data based on instructions or codes programmed therein corresponding to one or more routines.

[0042] The controller 12 can be coupled to the wireless communication device 156 for enabling the vehicle 102 to communicate directly with the network cloud 160. Using wireless communication 150 via the device 156, the vehicle 102 can retrieve data from the network cloud 160 regarding current and / or upcoming environmental conditions such as ambient humidity, temperature, pressure, etc. Upon completion of a driving cycle, the database 13 within the controller 12 can be updated with pilot information including driver behavior data, engine operating conditions, date and time information, and traffic information. Additionally, in some examples, the controller can communicate with a remote engine start receiver (or transceiver) that receives a wireless signal from a key fob having a remote start button, the remote start button being actuated by a vehicle driver from a location remote from the vehicle's position. In other examples (not shown), remote engine start can be initiated via a cellular phone or a smartphone-based system, where the user's cellular phone sends data to a server and the server communicates with the vehicle to start the engine.

[0043] The controller 12 can be communicatively coupled to other vehicles or infrastructure using suitable communication techniques known in the art. For example, the control system 14 can be coupled to other vehicles or infrastructure via the wireless network 150, and the wireless communication 150 can include Wi-Fi, Bluetooth, a type of cellular service, a wireless data transfer protocol, etc. The control system 14 can broadcast (and receive) information regarding vehicle data, vehicle diagnostics, traffic conditions, vehicle location information, vehicle operating procedures, etc. via vehicle-to-vehicle (V2V), vehicle-to-infrastructure-to-vehicle (V2I2V), and / or vehicle-to-infrastructure (V2I or V2X) technologies. The communication and information exchanged between the vehicle and / or infrastructure can be directed between the vehicle / infrastructure or can be multi-hop. In some examples, longer-range communication (e.g., WiMax) can be used in combination with V2V, V2I2V, etc. to extend the coverage area for several miles. In still some other examples, the vehicle control system 14 can communicate wirelessly with other vehicles or infrastructure via the network cloud 160 and the Internet.

[0044] The vehicle system 102 can also include an on-vehicle navigation system 184 (e.g., a global positioning system) with which a vehicle driver can interact. The navigation system 184 can include one or more position sensors for assisting in estimating vehicle speed, vehicle height, vehicle position / location, etc. This information can be used to infer engine operating parameters such as local atmospheric pressure. As described above, the control system 14 can be further configured to receive information via the Internet or other communication networks. Information received from the GPS can be cross-referenced with information available via the Internet to determine local climate conditions, local vehicle regulations, etc. In some examples, the information from the GPS can enable the collection of vehicle location information, traffic information, etc. by the vehicle.

[0045] In some examples, the controller may be placed in a reduced power mode or sleep mode, wherein the controller maintains only basic functionality and operates with lower battery consumption than in a corresponding wake-up mode. For example, the controller may be placed in sleep mode after a vehicle shutdown event so that a diagnostic routine is performed for a certain duration after the vehicle shutdown event. The controller may have a wake-up input that allows the controller to return to the wake-up mode based on input received from one or more sensors. For example, the opening of a vehicle door may trigger a return to the wake-up mode, or a remote start event may trigger a return to the wake-up mode.

[0046] In some examples, the vehicle 102 may be a hybrid vehicle having multiple torque sources available to one or more wheels 171. In the example shown, the vehicle 102 includes an engine 10 and an electric machine 52. The electric machine 52 may be a motor or a motor / generator. When one or more clutches 172 are engaged, the crankshaft 174 of the engine 10 and the electric machine 52 are connected to the wheels 171 via the transmission 54. In the depicted example, a first clutch is disposed between the crankshaft 174 and the electric machine 52, and a second clutch is disposed between the electric machine 52 and the transmission 54. The controller 12 may send a signal to an actuator of each clutch 172 to engage or disengage the clutch to connect or disconnect the crankshaft from the electric machine 52 and components connected thereto, and / or to connect or disconnect the electric machine 52 from the transmission 54 and components connected thereto. The transmission 54 may be a gearbox, a planetary gear system, or other type of transmission. The powertrain may be configured in various ways, including parallel, series, or series-connected hybrid vehicles.

[0047] Electric machine 52 receives power from traction battery 58 to provide torque to wheels 171. Electric machine 52 may also operate as a generator to provide power to charge traction battery 58, such as during braking operations. In some examples, traction battery 58 may include the same energy storage device as onboard energy storage device 151.

[0048] In some examples, fuel economy gauge 194 may indicate fuel efficiency to indicate if fuel efficiency has decreased due to degradation of a vehicle system (eg, a wastegate stuck open).

[0049] The engine 10 may be configured with an S / S feature 183 (also referred to herein as an S / S system) communicatively coupled to the control system 14, wherein if selected idle-stop conditions are met, the control system 14 may automatically shut down the internal combustion engine 10 (idle-stop the internal combustion engine 10) without receiving driver input to shut down the engine. These selected idle-stop conditions may, for example, include a torque demand less than a threshold, an engine speed less than a threshold engine speed (as monitored, for example, via an engine speed sensor 132), a vehicle speed lower than a threshold vehicle speed (e.g., 5 mph), an onboard energy storage device being fully charged, no request being received for air conditioning, etc. Similarly, energy may be automatically restarted in response to a torque demand above a threshold, a battery requesting charging, an air conditioning compressor requesting operation, etc. In one example, the engine may be restarted in response to the driver applying an accelerator pedal after being stopped for a certain duration (e.g., at a traffic signal). The engine may be cranked without fuel via a motor or electric machine coupled to the engine crankshaft until a desired engine speed is reached, after which the motor or electric machine may be disabled and the engine fuel supply is restored. After that, engine combustion can support engine rotation. Due to automatic start / stop, fuel consumption and exhaust emissions can be reduced.

[0050] Additionally, in some examples, intake manifold 22 may be selectively fluidly coupled to evaporative emissions system 178, which may be selectively fluidly coupled to a fuel system (not shown). More specifically, canister purge valve 179 may fluidly couple the intake manifold to the evaporative emissions system. For example, the evaporative emissions system may include a fuel vapor storage canister to capture and store fuel vapors from the fuel system, which may then be purged to the engine under select engine operating conditions via commanding the canister purge valve to open.

[0051] Figure 2 Describing can include Figure 1 2. An exemplary embodiment of a combustion chamber or cylinder in engine 10 depicted in FIG. Cylinder (i.e., combustion chamber) 30 may include combustion chamber walls 236, with piston 238 positioned in combustion chamber walls 236. Piston 238 may include one or more piston rings 268. For example, one or more piston rings 268 may function to seal cylinder 30 to assist the piston in heat transfer and regulate fuel consumption. Piston 238 may be coupled to crankshaft 174 so that reciprocating motion of the piston is converted into rotational motion of the crankshaft. Crankshaft 174 may be coupled to at least one drive wheel of a passenger vehicle via a transmission system. In addition, a starter motor (e.g., 52) may be coupled to crankshaft 174 via a flywheel to enable a starting operation of engine 10 and / or to rotate the engine in an unfueled mode.

[0052] Cylinder 30 may receive intake air via intake passage 244 (e.g., 22), which may be one of a plurality of intake passages coupled to cylinder 30. Intake passage 244 may communicate with other cylinders of engine 10 in addition to cylinder 30. In some embodiments, one or more intake passages may include a boosting device, such as a turbocharger or a supercharger. Exhaust passage 248 (e.g., 36) may receive exhaust gas from cylinder 30 as well as from other cylinders of engine 10.

[0053] Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 30 is shown as including at least one intake poppet valve 256 and at least one exhaust poppet valve 250 located at an upper region of cylinder 30. In some embodiments, each cylinder of engine 10, including cylinder 30, may include at least two intake poppet valves and at least two exhaust poppet valves located at an upper region of the cylinder.

[0054] Intake valve 256 may be controlled by the controller via actuator 252. Similarly, exhaust valve 250 may be controlled by the controller via actuator 254. During some conditions, the controller may vary the signals provided to actuators 252 and 254 to control the opening and closing of the respective intake and exhaust valves. The positions of intake valve 256 and exhaust valve 250 may be determined by respective position sensors 199a and 199b, respectively. The valve actuators may be electric valve actuated or cam actuated, or a combination thereof. The intake valve timing and exhaust valve timing may be controlled simultaneously, or any possibility of variable intake cam timing, variable exhaust cam timing, dual independent variable cam timing (TiVCT), or fixed cam timing may be used. Each cam actuation system may include one or more cams (e.g., actuators 252 and / or 254) and may utilize one or more of a cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) system that may be operated by a controller to vary valve operation. For example, cylinder 30 may optionally include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation including CPS and / or VCT. In other embodiments, the intake and exhaust valves may be controlled by a common valve actuator (or actuation system) or a variable valve timing actuator (or actuation system).

[0055] For illustrative purposes, Figure 2, is an example of TiVCT. In particular, an intake camshaft 281 and an exhaust camshaft 282 are shown. It should be understood that this configuration may enable the ability to independently advance or retard the timing of both the intake camshaft 281 and the exhaust camshaft 282. This ability may allow for improved power and torque, particularly at lower engine speeds (engine RPM), as well as improved fuel economy and reduced emissions. This ability may further enable precise control of the intake and exhaust valve positions, which in some examples may include positioning a particular cylinder so that the intake and exhaust valves are at least partially open.

[0056] In an example, a first oil pressure controlled actuator 283 may adjust the intake camshaft 281 under the control of the controller, and a second oil pressure controlled actuator 284 may adjust the rotation of the second camshaft 282. In this way, the first oil pressure controlled actuator and the second oil pressure controlled actuator may control the camshafts based on operating conditions to advance or retard the engine timing. For example, the controller may determine the engine timing using a crankshaft position sensor 197 and one or more position sensors 199a and 199b (e.g., 199).

[0057] Although in this article Figure 2 The examples depicted herein show the camshaft actuators (e.g., 283 and 284) as being oil pressure controlled, but there may be examples in which, instead of oil pressure driven cam phasing, cam torque actuation (CTA) may be employed which may utilize existing torsional energy in the valve train to rotate one or more camshafts as is generally understood in the art.

[0058] Additionally, it should be appreciated that in examples where the vehicle includes TiVCT, an EGR valve (eg, 152 ) and EGR passage 180 may not be included in the vehicle system because retarded exhaust cam timing may achieve similar results with recirculating exhaust gas.

[0059] Cylinder 30 may have a compression ratio, which is the ratio of the cylinder volume when piston 238 is at bottom dead center (BDC) to the cylinder volume when piston 238 is at top dead center (TDC). It should be understood that, as described herein, BDC may include the position of piston 238 closest to crankshaft 174, while TDC may include the position of piston 238 at the position farthest from crankshaft 174. In addition, it should be understood that, as discussed herein, TDC may be understood to be 180° from BDC. Conventionally, 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. For example, this may occur when using a higher octane fuel or a fuel with a higher latent enthalpy of vaporization. If direct injection is used due to its effect on engine knock, the compression ratio may also be increased.

[0060] In some embodiments, each cylinder of engine 10 may include a spark plug 292 for initiating combustion. Under select operating modes, an ignition system (not shown) may provide an ignition spark to cylinder 30 via spark plug 292 in response to a spark advance signal from a controller. However, in some embodiments, such as where engine 10 may initiate combustion by auto-ignition or by injection of fuel (as may be the case with some diesel engines), spark plug 292 may be omitted.

[0061] In some embodiments, each cylinder of engine 10 may be configured with one or more fuel injectors for providing fuel thereto. As a non-limiting example, cylinder 30 may include two fuel injectors (e.g., a port fuel injector and a direct fuel injector). Fuel injector 66 is shown coupled directly to cylinder 30 for injecting fuel directly therein in proportion to the pulse width of a signal received from a controller via an electronic driver. In this manner, fuel injector 66 provides what is known as direct injection (hereinafter referred to as "DI") of fuel into cylinder 30. Although Figure 2 Injector 66 is shown as a side injector, but the injector may also be located on top of the piston, such as near the location of spark plug 292. When the engine is operated with alcohol-based fuels, this location may improve mixing and combustion due to the lower volatility of some alcohol-based fuels. Alternatively, the injector may be located on top of and near the intake valve to improve mixing. Fuel may be delivered to fuel injector 66 from a high pressure fuel system including a fuel tank, a fuel pump, and a fuel rail. Alternatively, fuel may be delivered at low pressure by a single-stage fuel pump, in which case the timing of the direct fuel injection may be more limited during the compression stroke than if a high pressure fuel system is used.

[0062] During a single cycle of the cylinder, fuel may be delivered to the cylinder. As discussed herein, a single engine cycle includes an exhaust stroke, an intake stroke, a compression stroke, and a power stroke. It may be further appreciated that when the piston is within a threshold of TDC (e.g., within 5°) between the exhaust stroke and the intake stroke, both the intake valve and the exhaust valve may be at least partially open. Direct injection fuel may be delivered during the intake stroke and partially during the preceding exhaust stroke. In addition, direct injection fuel may be delivered as a single injection or multiple injections. These may include multiple injections during the compression stroke, multiple injections during the intake stroke, or a combination of some direct injections during the compression stroke and some direct injections during the intake stroke. When multiple direct injections are performed, the relative distribution of the total direct injection fuel between the intake stroke (direct) injection and the compression stroke (direct) injection may be referred to as a second injection ratio. For example, injecting a greater amount of directly injected fuel for a combustion event during the intake stroke may be an example of a higher second ratio of intake stroke direct injection, while injecting a greater amount of fuel for a combustion event during the compression stroke may be an example of a lower second ratio of intake stroke direct injection. Note that these are merely examples of different injection ratios, and a variety of other injection ratios may be used.

[0063] A positive crankcase ventilation (PCV) system may be coupled to the engine intake so that gases in the crankcase 262 may be exhausted from the crankcase in a controlled manner. The engine 10 may include a crankcase ventilation tube 258 and a PCV line 260 to exhaust gases from the crankcase 262 and into the intake manifold. In some examples, the PCV line 260 may include a PCV valve 264, which may be an electronically controlled valve (e.g., a powertrain control module (PCM) controlled valve) where a controller may command a signal to change the position of the valve from an open position (or high flow position) to a closed position (or low flow position), or vice versa, or any position therebetween.

[0064] As mentioned above, Figure 2 Only one cylinder of a multi-cylinder engine is shown. Thus, each cylinder may similarly include its own set of intake / exhaust valves, one or more fuel injectors, spark plugs, piston rings, etc.

[0065] Therefore, as discussed herein, the above Figure 1 to Figure 2The described system may implement a system for a hybrid vehicle, the hybrid vehicle including an engine including an intake port and an exhaust port, and a plurality of engine cylinders, each cylinder including an intake valve and an exhaust valve. An electric air compressor or electric supercharger may be coupled to the intake port at a location upstream of a charge air cooler, wherein the charge air cooler is located upstream of an intake throttle. The system may include a first actuator configured to control rotation of a first camshaft mechanically coupled to intake valves of a plurality of engine cylinders; and also include a second actuator configured to control rotation of a second camshaft mechanically coupled to exhaust valves of a plurality of engine cylinders. The system may also include a start / stop system configured to automatically stop the engine from burning air and fuel in response to a set of predetermined conditions being met.

[0066] The system may also include a controller storing instructions in a non-transitory memory that, when executed, cause the controller to activate an electric air compressor to flow cool air through a single cylinder of the engine when the engine stops burning air and fuel during a start / stop event. This action may be performed under conditions where a first temperature of the single cylinder is above a first threshold cylinder temperature, but where a second temperature of the engine is below the first threshold engine temperature. In this example, activating the electric air compressor to flow cool air through the single cylinder may also include commanding a throttle to open to a fully open position and controlling the first actuator and the second actuator to position an intake valve and an exhaust valve of the single cylinder to an at least partially open configuration.

[0067] The system may also include a wireless communication device and an onboard navigation system. Accordingly, the controller may store additional instructions to retrieve information related to a predicted duration of a start / stop event via the wireless communication device and / or the onboard navigation system. Upon the start / stop event, in response to the duration of the start / stop event being predicted to be greater than the amount of time predicted to reduce the first temperature of the single cylinder to the desired temperature, the controller may activate the electric air compressor to flow cool air through the single cylinder.

[0068] The system may also include a turbine positioned in the exhaust port, the turbine mechanically coupled to a mechanically driven compressor positioned upstream of the electric air compressor. The system may also include a wastegate passage, the wastegate passage including an actuatable wastegate, the wastegate passage configured to direct fluid flow around the turbine under conditions where the actuatable wastegate is open. Thus, the controller may store additional instructions to command opening of the wastegate at a start / stop event and just prior to starting the electric air compressor (e.g., within 5 seconds or less).

[0069] The system may also include a motor configured to spin the engine. In this example, the controller may store additional instructions to activate the electric air compressor and spin the engine without fuel to cool multiple engine cylinders, rather than flowing cool air through a single cylinder, when a second temperature of the engine is greater than a first threshold engine temperature.

[0070] Now turn Figure 3 , a high level flow chart of an exemplary method 300 for determining whether an indicated engine overheat condition includes a general engine overheat condition, where the overheat is not limited to a single cylinder, or where the indicated engine overheat condition includes a single cylinder overheat. The method includes scheduling a general engine cooling operation for a next S / S event in response to determining a general engine overheat condition, and scheduling a single cylinder cooling operation for a next S / S event in response to a single cylinder overheat condition. The method is respectively related to Figures 4 to 5 Detailed description. Thus, method 300 can provide engine cooling when other engine cooling methods are insufficient to maintain engine temperature within a desired range. Thus, employing method 300 can reduce the likelihood and / or extent of engine degradation due to an overheating condition. Method 300 will be described with reference to the systems described herein and will be described in detail in the following. Figure 1 to Figure 2 , but it should be understood that similar methods may be applicable to other systems without departing from the scope of the present disclosure. Instructions for executing method 300 and the remainder of the methods included herein may be based on instructions stored in non-transitory memory and in conjunction with sensors from the engine system (such as Figure 1 to Figure 2 The signals received by the temperature sensors, pressure sensors and other sensors described in Figure 1 According to the method described herein, the controller may use actuators such as an electric supercharger actuator (e.g., 155b), a throttle valve (e.g., 20), a wastegate actuator (e.g., 92), an EGR valve (e.g., 152), etc.

[0071] Method 300 begins at 302 and may include evaluating current vehicle and engine operating conditions. Operating conditions may be estimated, measured, and / or inferred and may include one or more vehicle conditions such as vehicle speed, battery state of charge, various engine conditions such as engine state (on or off), engine load, engine temperature, engine speed, torque demand, exhaust air-fuel ratio, various fuel system conditions such as fuel level, fuel type, fuel temperature, various evaporative emission system conditions such as fuel vapor canister load, fuel tank pressure, and various environmental conditions such as ambient temperature, humidity, barometric pressure, and the like.

[0072] At 302, estimating, measuring, and / or inferring engine temperature may be performed via one or more engine temperature sensors (e.g., 181) discussed above. For example, a general engine overheat condition may be measured or inferred based on an engine coolant temperature sensor and / or one or more CHT sensors, and an individual cylinder overheat condition may be estimated, measured, or inferred via one or more CHT sensors and / or one or more in-cylinder temperature sensors (where included).

[0073] In another example, inferences may be made regarding whether a single engine cylinder (or in some examples, more than one single engine cylinder) is overheating based on an on-board cylinder power balance test. In particular, in some examples, carbon accumulation in any particular engine cylinder may result in increased compression in the cylinder, which may therefore indicate that the cylinder is overheating. More specifically, engine speed and crankshaft angle may be monitored (e.g., via engine speed sensor 132 and crankshaft position sensor 197, respectively), and a sudden or unexpected acceleration in engine speed may be associated with a particular crankshaft position (e.g., crank angle) at which the acceleration occurs. Thus, such data may enable determination of which particular cylinder is producing increased torque (e.g., an increase in torque beyond an expected or predicted torque), which may be the result of a higher compression ratio due to carbon deposition. As discussed, such an indication may indicate that a particular cylinder is overheating.

[0074] In another example, additionally or alternatively, inferences as to whether a single engine cylinder (or in some examples more than one single engine cylinder) is overheating may be made based on data acquired from one or more knock sensors (e.g., 131), where such data may be acquired within a specific timing window that may enable a determination as to which specific cylinder is knocking, which may enable inferences as to whether such specific cylinder is overheating. For example, the timing window may be specific to the combustion period of each specific engine cylinder. More specifically, for a four-cylinder engine, there may be four timing windows, each timing window corresponding to a combustion event for each specific cylinder.

[0075] Thus, proceeding to step 306, method 300 may include indicating whether an engine overheat condition is identified. The engine overheat condition may include a general engine overheat, or may include an individual engine cylinder (or cylinders) overheating. The engine overheat condition may include an engine temperature above a threshold engine temperature, or an individual cylinder or cylinders above a threshold cylinder temperature. As will be discussed in detail below, the threshold engine temperature may be referred to as a first threshold engine temperature, and the threshold cylinder temperature may be referred to as a first threshold cylinder temperature.

[0076] If at 306, an engine overheat condition is not identified, then method 300 may proceed to 310 and may include maintaining the current vehicle operating conditions. In particular, if the vehicle is being propelled via the engine, then engine operation may be maintained based on driver demand. In another example, if the vehicle is being propelled at least partially via an electric machine (e.g., 52), then such conditions may be maintained. Then, method 300 may end. It should be understood that in conditions where an engine overheat is not identified, engine temperature may continue to be monitored throughout the current drive cycle so that engine overheat may be identified at any point in the current drive cycle.

[0077] Returning to step 306, if an engine overheat condition is identified, the method 300 may proceed to 314. At step 314, the method 300 may include an indication of whether a single cylinder overheat condition is identified. If a single engine cylinder overheat condition is not identified, the method 300 may proceed to 318, where a general engine cooling operation may be scheduled for the next S / S event. Scheduling a general engine cooling operation may include setting a flag at the controller so that in response to meeting the conditions for the S / S event during the current driving cycle, a general engine cooling operation may be started. In addition, at 318, mitigation actions may be taken to reduce the degree of the general engine overheat condition. Examples of mitigation actions may include starting one or more cooling fans (e.g., 187) to guide cool air toward the engine in an attempt to reduce the temperature. Other examples of mitigation actions may include stopping fuel injection to one engine cylinder while the engine continues to rotate via the remaining engine cylinders that are still receiving fuel, then resuming fuel supply and stopping fuel injection to another engine in a cyclic manner, and so on. More specifically, in an example where the engine comprises a four-cylinder engine, the first cylinder may be first defueled, then the second cylinder may be defueled while restoring fuel to the first cylinder. Next, the third cylinder may be defueled while restoring fuel to the second cylinder, and so on. It should be understood that in such an example, each cylinder may be defueled for a predetermined duration before restoring fuel. It should also be understood that in such an example, when a single cylinder is defueled, one or more intake and exhaust valves may continue to operate, thereby causing airflow through the cylinder that is defueled, which may be used in some examples to reduce the degree of engine overheating.

[0078] By taking mitigating actions and scheduling general engine cooling operations at 318, method 300 may proceed to 322. At 322, method 300 may include performing a Figure 4 The method 300 may then end.

[0079] Returning to 314, in response to identifying a single cylinder overheat state, method 300 may proceed to 326. At 326, method 300 may include scheduling a single engine cylinder cooling operation for the next S / S event. Scheduling a single engine cylinder cooling operation may include setting a flag at the controller so that in response to meeting the conditions for the S / S event during the current driving cycle, a general engine cooling operation may be started. In addition, at 326, mitigation actions may be taken to reduce the degree of the single engine cylinder overheat state. Examples of mitigation actions may include starting one or more cooling fans (e.g., 187) to guide cold air toward the engine in an attempt to reduce the temperature of the overheated cylinder. Similar to what is discussed at 318 of method 300, other examples of mitigation actions may include stopping fuel injection to a single engine cylinder identified as overheated. In particular, a single engine cylinder may be cut off from fuel supply for a predetermined duration, wherein after the predetermined duration, the fuel supply may be restored. It will be appreciated that while fuel supply to an individual engine cylinder is shut off, one or more intake and exhaust valves may continue to operate, thereby causing air to be directed through the individual engine cylinder, which may assist in cooling the cylinder.

[0080] By scheduling individual engine cylinder cooling operations, and in response to taking mitigating actions, method 300 may proceed to 330. At 330, method 300 may include performing a cooling operation based on Figure 6 The single engine cylinder cooling operation is performed. Method 300 may then end.

[0081] Returning to step 314, it should be recognized here that in some examples, more than one individual cylinder may be overheating, but the conditions may not be such that general engine cooling operation is warranted. For example, consider an eight-cylinder engine in which two engine cylinders are overheating. In this case, in some examples, it may be desirable to perform general engine cooling operations, while in other examples, it may be desirable to perform individual engine cylinder cooling operations in a sequential manner, which will be discussed in more detail below. More particularly, as will be described in detail below, both individual engine cylinder cooling operations and general engine cooling operations may utilize energy derived from an on-board energy storage device (e.g., 151) and / or a traction battery (e.g., 58). As discussed, in some examples, the on-board energy storage device and the traction battery may include the same on-board energy storage device, and therefore will be referred to herein as the "on-board energy storage device." General engine cooling operations may utilize a greater amount of energy from the on-board energy storage device than individual engine cylinder cooling operations. Thus, in some examples, in the case where more than one single engine cylinder is indicated as overheated, the controller may determine the state of charge of the onboard energy storage device to indicate whether it is desired to perform a general engine cooling strategy or to perform a single engine cooling strategy sequentially. More specifically, in the case where more than one single engine cylinder is indicated as overheated, if the SOC is indicated to be below a threshold SOC, then a single engine cooling operation method may be performed in a sequential manner, which may reduce the energy utilized via the onboard energy storage device. Alternatively, if the SOC is indicated to be greater than a threshold SOC, then a general engine cooling operation may be performed. The threshold SOC may be based on the number of engine cylinders indicated to be overheated, and may be further based on the degree of overheating of the engine cylinders (e.g., the degree to which each cylinder is above a first threshold cylinder temperature). For example, if three of the eight engine cylinders are overheated and the SOC is greater than a threshold, then it may be desirable to perform a general engine cooling strategy to reduce the complexity of performing sequential single engine cooling operations. However, if the SOC is below a threshold, then single engine cooling operations may be performed in a sequential manner.

[0082] Now turn Figure 4 , a high-level flow chart of an exemplary method 400 for performing general engine cooling operations in response to scheduling general cooling operations according to step 318 of method 300 is shown. More specifically, in Figure 4 General cooling operations may include spinning the vehicle engine without fuel during the S / S event and activating an electric supercharger positioned upstream of the engine in the engine air intake. In this way, under conditions that may exacerbate engine overheating during the S / S event, where vehicle underhood temperatures may continue to rise, such potential exacerbation of engine overheating may be reduced, and in some cases avoided entirely.

[0083] The method 400 will be described with reference to the system described herein and will be described in detail in the following manner. Figure 1 to Figure 2 , but it should be understood that similar methods may be applicable to other systems without departing from the scope of the present disclosure. Instructions for executing method 400 and the remainder of the methods included herein may be based on instructions stored in non-transitory memory and in conjunction with sensors from the engine system (such as Figure 1 to Figure 2 The signals received by the temperature sensors, pressure sensors and other sensors described in Figure 1 According to the method described herein, the controller may employ actuators such as an electric supercharger actuator (e.g., 155b), a throttle valve (e.g., 20), a wastegate actuator (e.g., 92), an EGR valve (e.g., 152) (where included), etc.

[0084] At 402, method 400 may include indicating whether conditions for performing general engine cooling operations are met. Satisfying conditions at 402 may include an S / S event, which occurs, for example, in the same driving cycle as the driving cycle indicating engine overheating. Satisfying conditions at 402 may also include an indication that the temperature of the engine still constitutes an overheated engine state. In other words, as discussed above at step 318 of method 300, mitigation actions may be taken to attempt to reduce engine temperature before the S / S event. If this mitigation action successfully reduces engine temperature so that an overheated engine state is no longer indicated, conditions for performing general engine cooling operations may be met. In other words, if the engine temperature has been sufficiently reduced during the driving cycle, energy may be saved by avoiding performing general engine cooling operations.

[0085] If conditions for performing general engine cooling operations are not indicated at 402, method 400 may proceed to 406. At 406, method 400 may include maintaining current vehicle operating conditions. For example, the engine may remain off for the S / S event. However, engine temperature may continue to be monitored at 406, and if engine temperature rises to a point indicating an engine overheat condition, conditions for performing general engine cooling operations may be indicated.

[0086] In response to satisfying the conditions for performing general engine cooling operations, method 400 may proceed to 410. At 410, method 400 may include rotating the engine without fuel. Rotating the engine without fuel may include a controller commanding an electric motor (e.g., 58) or a starter motor to rotate the engine without providing a fuel supply. The engine may be controlled to rotate without fuel in a forward or default direction, wherein the forward or default direction includes the same direction of rotation as when the engine burns air or fuel. The engine may rotate at a predetermined speed, or may be controlled to a speed that depends on the degree of overheating of the engine. The predetermined speed may include a speed at which rotating the engine without fuel does not adversely affect the cooling operation. In other words, the speed may be controlled to minimize the heat generated by rotating the engine without fuel, while allowing the maximum amount of airflow to pass through the engine for a given speed.

[0087] Although not explicitly shown, several other actions may be performed at step 410. In particular, the intake throttle (e.g., 20) may be commanded to a fully open position via a controller, the EGR valve (e.g., 152) (where included) may be commanded to a fully closed position via a controller, and the canister purge valve (e.g., 179) may be commanded to a fully closed position via a controller. Further, in some examples, where included, a wastegate or wastegate valve (e.g., 91) may be commanded to a fully open position. By commanding the wastegate to open, air directed through the engine (discussed in detail below) may experience less resistance than when the wastegate is in a fully closed configuration. More particularly, with the wastegate open, airflow may be directed around a more restrictive turbine (e.g., 116), thereby promoting more airflow through the engine. In the case where the wastegate includes a spring-loaded wastegate, the wastegate may be maintained closed during operation, which may not substantially affect cooling operation compared to the case where the wastegate can be commanded open. For example, in some examples, opening the wastegate and / or throttle may occur just prior to spinning the engine without fuel (eg, in less than 30 seconds).

[0088] Advancing to 414, method 400 may include activating an electric supercharger (e.g., 155) to direct air through the CAC and through the engine. With the engine spinning without fuel, as the engine progresses through many engine cycles, as each of the engine cylinder valves (intake and exhaust valves) opens and closes, the cool air directed through the engine may be used to cool each of the engine cylinders. The electric supercharger may be activated at a predetermined speed or a predetermined power level. In some examples, the electric supercharger may be controlled to a speed and / or power level that is dependent on the engine temperature. For example, as the engine temperature increases, the electric supercharger may be controlled to a higher speed and / or power level to cool the engine.

[0089] In the event that the electric supercharger is activated at 414, method 400 may proceed to 418. At 418, method 400 may include continuing to monitor the engine temperature, and in response to the engine temperature decreasing to below a threshold engine temperature, the cooling operation may be terminated. More specifically, as discussed above, the temperature indicating an engine overheat condition may include a first threshold engine temperature. Therefore, at 418, the threshold engine temperature at which the cooling operation may be terminated may include a second threshold engine temperature. The second threshold engine temperature may be lower (colder) than the first threshold engine temperature. In other words, if the cooling operation only reduces the engine temperature to the first threshold temperature, the possibility of engine overheating is highly likely to occur in a short time frame. However, in some examples, by reducing the engine temperature to a second threshold value below the first threshold, the engine temperature may be maintained below the first threshold temperature for a longer duration and possibly for the rest of the driving cycle.

[0090] If a decrease in engine temperature to or below the second threshold engine temperature is not indicated at 418, method 400 may proceed to 422. At 422, method 400 may include maintaining the electric supercharger activated and the engine may continue to spin without fuel.

[0091] In response to the engine temperature decreasing to a second threshold engine temperature or below, method 400 may proceed to 426. At 426, method 400 may include terminating general engine cooling operations. More specifically, terminating general engine cooling operations may include the controller sending a signal to the electric supercharger to stop actuating it. In addition, the controller may send a signal to the motor to command the motor to stop rotating the engine without fuel, at which point the engine may rotate to a standstill. In addition, terminating engine cooling operations may include the controller sending a signal to the wastegate to actuate it to a fully closed position, as long as the wastegate is commanded to open for general engine cooling operations. In addition, in some examples, if a threshold duration has passed, wherein the engine temperature has not yet reached the second threshold engine temperature, or if the battery SOC drops below a predetermined value, then engine cooling may be terminated.

[0092] Proceeding to 430, method 400 may include continuing to monitor the duration of the engine temperature S / S event. In the event that the engine temperature rises to the first threshold engine temperature, then method 400 may include returning to step 402, where general cooling operations may again be performed to reduce the engine temperature to the second threshold engine temperature, as long as conditions are met to do so.

[0093] Continuing to 434, method 400 may include indicating whether conditions are met for automatically restarting the engine to combust air and fuel. More specifically, the vehicle operator may depress the accelerator pedal, requesting wheel torque. The requested wheel torque being greater than a threshold wheel torque or the accelerator pedal position being greater than a threshold accelerator pedal position may indicate a request to automatically restart the engine. If at 434, it is not indicated that the automatic restart conditions are met, then method 400 may proceed to 438 and may include maintaining the engine stopped. In other words, the current vehicle and engine operating conditions may be maintained and the engine temperature may continue to be monitored.

[0094] Alternatively, in response to indicating that the automatic restart conditions are met, method 400 may proceed to 442. At 442, method 400 may include performing an automatic restart. Restarting the engine may include the controller commanding a starter motor or electric machine to rotate the engine until a threshold engine starting speed is reached, and then providing a fuel supply and spark to cause the engine to combust air and fuel. In one example, the engine may be fueled to provide a defined engine speed profile and a target engine torque. Method 400 may then end.

[0095] Although not explicitly shown, it should be understood that there may be situations where a general engine cooling operation is initiated, but where an engine restart is requested before the engine has cooled to the second threshold engine temperature. In some examples, this situation may be unavoidable, however, it may be desirable to minimize this situation as much as possible because when this situation occurs, energy may be wasted while performing a portion of the cooling operation, but without the engine temperature being reduced to the second threshold engine temperature. For example, this wasted energy usage may negatively affect fuel economy.

[0096] To avoid this, in some examples, the conditions for performing a general engine cooling operation that are satisfied at 402 may include an indication that a particular S / S event may or is predicted to have a duration greater than the expected duration of a general engine cooling operation. For example, the duration of a general cooling operation may be based on engine temperature, ambient temperature, mass air flow through the engine totaled in a previous driving cycle, etc. As an example, a lookup table may be stored at the controller, which may be queried in an S / S event in which a general engine cooling operation is scheduled in order to obtain an estimate of the duration for which a general engine cooling operation is expected to be performed. In addition, as discussed above, guidance information about a driving cycle may be recorded at the controller, which guidance information may constitute known guidance information. Therefore, based on known guidance, the duration of a particular S / S event may be determined. For example, such determination may be combined with GPS (e.g., 184). In addition, in some examples, such determination may involve traffic information obtained wirelessly via the controller in combination with GPS. In this way, it is possible to predict / estimate how long a particular S / S event may last. Equipped with such information, the vehicle controller may determine whether to perform a general engine cooling operation. More specifically, if the general engine cooling operation is expected to proceed for a duration longer than the predicted or known stop duration, the cooling operation may not be initiated, which may avoid undesirable energy usage. Alternatively, if the general cooling operation is expected to proceed for a duration shorter than the predicted or known stop duration, the cooling operation may be initiated. In other words, in such an example, the conditions for conducting the general engine cooling operation may be met.

[0097] While the above description relates to general engine cooling operations, it should be understood that such description is equally applicable to individual engine cylinder cooling operations described in further detail below.

[0098] Now turn Figure 5 , a high-level flow chart of an exemplary method 500 for performing a single engine cylinder cooling operation in response to scheduling a single engine cylinder cooling operation according to step 326 of method 300 is shown. More specifically, in Figure 5 Performing individual engine cylinder cooling operations at the S / S event may include parking the cylinder indicated as overheating with the cylinder's intake and exhaust ports at least partially open, and then flowing air through the cylinder via actuation of an electric supercharger (e.g., 155). In this way, individual engine cylinders indicated as overheating may be effectively cooled during an S / S event, where otherwise cylinder temperatures may continue to rise if such action is not taken, which may contribute to undesirable engine degradation.

[0099] The method 500 will be described with reference to the system described herein and will be described in detail in the following manner. Figure 1 to Figure 2, but it should be understood that similar methods may be applicable to other systems without departing from the scope of the present disclosure. Instructions for executing method 500 and the remainder of the methods included herein may be based on instructions stored in non-transitory memory and in conjunction with sensors from the engine system (such as Figure 1 to Figure 2 The signals received by the temperature sensors, pressure sensors and other sensors described in Figure 1 According to the method described herein, the controller may employ actuators such as an electric supercharger actuator (e.g., 155b), a throttle valve (e.g., 20), a wastegate actuator (e.g., 92), an EGR valve (e.g., 152) (if included), a first oil pressure-controlled actuator (e.g., 283), a second oil pressure-controlled actuator (e.g., 284), etc.

[0100] Method 500 begins at 502 and may include indicating whether conditions for performing a single engine cylinder cooling operation are met. The conditions met at 502 may include an S / S event that occurs in conjunction with an indication of a single cylinder overheat condition (see Figure 3 The condition being satisfied at 502 may also include an indication that the temperature of a single cylinder (or multiple cylinders) is still in an overheated state. In other words, even though mitigation actions (see step 326 of method 300) may be taken to reduce the overheated state of a single cylinder or multiple cylinders, in some examples the mitigation actions may not be sufficient to reduce the temperature of a single cylinder or multiple cylinders so that an overheated state is no longer indicated. More specifically, as discussed above, a single cylinder overheated state may include a single cylinder temperature being higher than a first threshold cylinder temperature. Therefore, if the temperature of the cylinder or cylinders is higher than the first threshold cylinder temperature, it may indicate that the condition for performing a single cylinder cooling operation is satisfied.

[0101] Still in other examples, as described above, the condition satisfied at 502 may include an indication that a particular S / S event is likely or predicted to have a duration greater than the expected duration of a single engine cylinder cooling operation. The duration of a single cylinder cooling operation may be based on engine temperature, ambient temperature, mass air flow through the engine totaled in previous driving cycles, etc. For example, a lookup table stored at the controller may include an estimate of the duration for which a single cylinder cooling operation is expected to be completed. In addition, guidance information about the driving cycle may be stored at the controller, thereby constituting known guidance information. Based on known guidance, the duration of a particular S / S event may be determined. In some examples, such determination may be combined with GPS and may involve traffic information obtained wirelessly via the controller. In this way, it is possible to predict / estimate how long a particular S / S event may last. Equipped with such information, the vehicle controller may determine whether to perform a single engine cylinder cooling operation. More specifically, if a single engine cylinder cooling operation is predicted to be performed for a duration longer than the predicted or known stop duration, the cooling operation may not be started, which may avoid undesirable energy usage. Such an indication may be particularly useful in examples where more than one cylinder is scheduled for a single engine cylinder cooling operation.Alternatively, if a single engine cylinder cooling operation is expected to occur for a duration that is less than a predicted or known stop duration, then the cooling operation may be initiated.

[0102] As discussed herein, performing a "single engine cylinder cooling operation" may involve cooling one cylinder, or may involve cooling more than one cylinder, wherein when the cooling operation involves cooling more than one cylinder, the cylinders are cooled in a sequential manner, with only one cylinder being cooled at a time. Thus, the term "single engine cylinder cooling operation" specifically refers to cooling one particular cylinder at a time, even though there may be circumstances where cooling of more than one cylinder is requested.

[0103] Conditions satisfied at 502 may also include the onboard energy storage device SOC being above a predetermined level sufficient to enable single cylinder cooling operation without adversely affecting downstream applications (eg, engine starting, etc.) that utilize energy from the onboard energy storage device or battery.

[0104] If the conditions for performing a single engine cylinder cooling operation are not indicated at 502, then the method 500 may proceed to 506. At 506, the method 500 may include maintaining the current vehicle operating conditions. For example, if the vehicle is in an S / S event, but the conditions for performing a cooling operation are not met, then the vehicle engine may be maintained off, and the electric supercharger may be maintained off, etc. If the vehicle is operating with the engine combusting air and fuel, then such conditions may be maintained. In the case where the vehicle is being propelled at least partially via electric power, such operation may be maintained.

[0105] Returning to 502, in response to conditions being met for performing a single engine cylinder cooling operation, method 500 may proceed to 510. At 510, method 500 may include parking the overheated cylinder with the intake and exhaust valves at least partially open. In the case where only one cylinder is scheduled for cooling operation, the particular cylinder may be parked with its intake and exhaust valves at least partially open. In the case where more than one cylinder is scheduled for cooling operation, only one cylinder may be first parked with its intake and exhaust valves at least partially open. In some examples where more than one cylinder is scheduled for cooling operation, the controller may determine which cylinder is overheated to the greatest extent, and may first park the cylinder with the intake and exhaust valves at least partially open. In this way, mitigation actions may be taken on the cylinder that is overheated to the greatest extent, followed by mitigation actions on the other one or more cylinders.

[0106] In a vehicle configured with TiVCT, such steps may include controlling a first oil pressure controlled actuator (e.g., 283) for an intake camshaft via a controller, and may also include controlling a second oil pressure controlled actuator (e.g., 284) for an exhaust camshaft via a controller to ensure that an intake valve for a selected cylinder and an exhaust valve for a selected cylinder are at least partially open. It should be understood that controlling the intake and exhaust valves to be at least partially open may include controlling the intake and exhaust valves to be as open as possible given the inherent constraints of the engine system. In this way, cooling airflow through the cylinders may be maximized, as will be further described below.

[0107] In some examples, controlling the intake and exhaust valves to at least partially open positions may include the controller commanding an electric machine (eg, 52 ) to control or assist engine rotation such that the intake and exhaust valves are at least partially open.

[0108] It will be appreciated that parking a cylinder with its intake and exhaust valves at least partially open may include the cylinder's piston being within a threshold degree (eg, 5°) of TDC.

[0109] Although not explicitly shown, several other actions may be performed at step 510. In particular, the intake throttle (e.g., 20) may be commanded to a fully open position via a controller, the EGR valve (e.g., 152) (where included) may be commanded to a fully closed position via a controller, and the canister purge valve (e.g., 179) may be commanded to a fully closed position via a controller. Further, in some examples, where included, a wastegate or wastegate valve (e.g., 91) may be commanded to a fully open position. By commanding the wastegate to open, air directed through the engine (discussed in detail below) may experience less resistance than when the wastegate is in a fully closed configuration. More particularly, with the wastegate open, airflow may be directed around a more restrictive turbine (e.g., 116), thereby promoting more airflow through the engine. In the case where the wastegate includes a spring-loaded wastegate, the wastegate may be maintained closed during operation, which may not substantially affect cooling operation compared to the case where the wastegate can be commanded open.

[0110] Proceeding to 514, method 500 may include starting an electric supercharger (e.g., 155) to direct air through the CAC and through the engine cylinders with the intake and exhaust valves at least partially open. By starting the electric supercharger, cold air may be directed through the selected cylinders and may therefore be used to cool the selected cylinders. The electric supercharger may be started at a predetermined speed or a predetermined power level, the predetermined speed and / or predetermined power level being specific to a single engine cylinder cooling operation. More specifically, in some examples, the predetermined speed and / or predetermined power level may be different from a single engine cylinder cooling operation as described above for a general engine cooling operation. However, in other examples, the predetermined speed and / or power level may be the same between a general engine cooling operation and a single engine cylinder cooling operation.

[0111] In some examples, the electric supercharger may be controlled to a speed and / or power level that is dependent on the temperature of a single engine cylinder and the degree of overheating. For example, as the temperature of a single cylinder increases, the electric supercharger may be controlled to a higher speed and / or power level to more effectively cool the cylinder. Additionally, in some examples, the speed and / or power level of the electric supercharger may be controlled based on the known / predicted duration of the S / S event. For example, under conditions where the known / predicted S / S event is shorter, the speed and / or power level of the electric supercharger may be increased to effectively cool the cylinder faster. Alternatively, under conditions where the known / predicted S / S event is longer, the speed and / or power level of the electric supercharger may be reduced.

[0112] In some examples, a pressure sensor (e.g., 165) positioned in the exhaust system downstream of the turbine (e.g., 116) can be used to monitor the air flow directed through a single cylinder. In one example, the air flow may include an expected air flow for a particular single cylinder under the condition that the intake and exhaust valves of the single cylinder are positioned to be at least partially open. If the air flow is significantly different from the expected (e.g., greater than 10% different), it may indicate that there is a potential problem with one or more of the intake / exhaust valves, a potential problem with a system involving cam timing (e.g., TiVCT), etc. In such an example, a malfunction indicator light at the instrument panel may be illuminated to alert the vehicle driver of a request to service the vehicle. If the monitored flow is greater than a degradation threshold that is different from the expected flow, the cooling method may be interrupted, and the controller may propel the vehicle via electrical commands as frequently as possible to avoid further engine degradation due to overheating.

[0113] In the event that the electric supercharger is activated at 514, method 500 may proceed to 518. At 518, method 500 may include continuing to monitor the temperature of a single engine cylinder (e.g., via a CHT sensor or an in-cylinder temperature sensor), and in response to the cylinder temperature decreasing below a threshold cylinder temperature, the cooling operation may be terminated. More specifically, as discussed above, the temperature indicating a single cylinder overheat condition may include a first threshold cylinder temperature. Therefore, at 518, the threshold engine temperature at which the cooling operation may be terminated may include a second threshold cylinder temperature. The second threshold cylinder temperature may be lower (colder) than the first threshold cylinder temperature. In other words, if the cooling operation only reduces the cylinder temperature to the first threshold cylinder temperature, then the probability for the cylinder overheating is highly likely to occur in a short time frame. However, in some examples, by reducing the cylinder temperature to a second threshold cylinder temperature that is lower than the first threshold cylinder temperature, the cylinder temperature may be maintained below the first threshold cylinder temperature for a longer duration and possibly for the remainder of the driving cycle.

[0114] If a decrease in cylinder temperature to or below the second threshold cylinder temperature is not indicated at 518, method 500 may proceed to 522. At 522, method 500 may include maintaining the electric supercharger activated with the selected cylinder intake and exhaust valves maintained at least partially open.

[0115] In response to the single cylinder cooling operation reducing the temperature of the selected cylinder to or below the second threshold cylinder temperature, method 500 may proceed to 526. At 526, method 500 may include indicating whether cooling of any other cylinders has been requested via the single cylinder cooling operation. If so, method 500 may return to 502 and may include indicating whether the conditions for performing the single cooling operation on the additional cylinders are still met. Similar to the above discussion, if it is indicated that the additional cylinder is above the first threshold cylinder temperature, and if it is indicated that there is sufficient time to perform the additional cooling operation before requesting to restart the engine, then the conditions may be met. Satisfying the conditions may also include the battery SOC being greater than a predetermined SOC level for performing the single cylinder cooling operation.

[0116] It will be appreciated that in some examples, the predetermined SOC level for performing a single engine cylinder cooling operation may be adjusted based on the number of cylinders selected for single cylinder cooling operation. For example, the predetermined SOC level may be higher if more than one cylinder is selected for cooling than if only one cylinder is selected.

[0117] In the example where additional cylinders are selected for cooling at 526, it should be appreciated that the method for cooling such additional one or more cylinders may be substantially the same as the method described at steps 502-526. Parking the additional cylinders with their intake and exhaust valves at least partially open may include rotating the engine via, for example, an electric motor, and may also include controlling a first oil pressure-controlled actuator (e.g., 283) and a second oil pressure-controlled actuator (e.g., 284) such that the intake and exhaust valves of the particular selected cylinders are controlled to be at least partially open.

[0118] At 526, in the event that additional cylinder cooling is not requested, method 500 may proceed to 530. At 530, method 500 may include terminating the single engine cylinder cooling operation. More specifically, terminating the single engine cylinder cooling operation may include the controller sending a signal to the electric supercharger to cause it to stop actuating. In addition, the controller may send a signal to the electric motor or motor commanding the electric motor or motor to rotate the engine to a desired engine position without fuel for engine starting. However, in other examples, the engine may not rotate after the single engine cylinder cooling operation is terminated. In addition, terminating the single engine cylinder cooling operation may include the controller sending a signal to the wastegate to cause it to actuate to a fully closed position, as long as the wastegate is commanded open for general engine cooling operations.

[0119] Proceeding to 534, method 500 may include continuing to monitor the temperature of the single or multiple engine cylinders and / or the duration of the general engine temperature S / S event. In the event that the temperature of one or more single engine cylinders rises to or above the first threshold cylinder temperature, then method 500 may return to 502, where single engine cylinder cooling operations may be performed again as described, provided that conditions are met to do so. In the example where for some reason the general engine temperature climbs to or above the first threshold engine temperature, then method 500 may include proceeding to method 400 (as described above), which may include performing general engine cooling operations, provided that conditions are met to do so.

[0120] Continuing to 538, method 500 may include indicating whether conditions are met for automatically restarting the engine to combust air and fuel. As described above, the vehicle operator may depress the accelerator pedal, requesting wheel torque. The requested wheel torque greater than a threshold wheel torque or the accelerator pedal position greater than a threshold accelerator pedal position may indicate a request to automatically restart the engine. If at 538, it is not indicated that the automatic restart conditions are met, then method 500 may proceed to 542 and may include maintaining the engine stopped. In other words, the current vehicle and engine operating conditions may be maintained and the engine temperature may continue to be monitored.

[0121] Alternatively, in response to indicating that the automatic restart conditions are met, method 500 may proceed to 546. At 546, method 500 may include performing an automatic restart. Restarting the engine may include the controller commanding a starter motor or electric machine to rotate the engine until a threshold engine starting speed is reached, and then providing a fuel supply and spark to cause the engine to combust air and fuel. In one example, the engine may be fueled to provide a defined engine speed profile and a target engine torque. Method 500 may then end.

[0122] Therefore, the above Figures 3 to 5The depicted flowchart may implement a method including: activating an electric compressor in an intake of a vehicle engine during a start / stop event in which the engine is not combusting air and fuel to direct airflow through a first single cylinder of the engine to reduce a temperature of the first single cylinder to a desired temperature prior to requesting to restart the engine. The method may include positioning the first single cylinder so that both an intake valve and an exhaust valve of the first single cylinder are in an at least partially open configuration to direct the airflow through the first single cylinder. Positioning the first single cylinder so that both the intake valve and the exhaust valve are in an at least partially open configuration may include adjusting a timing of opening the intake valve and the exhaust valve via controlling a rotation of a first camshaft mechanically coupled to the intake valve and via controlling a rotation of a second camshaft mechanically coupled to the exhaust valve.

[0123] The method may also include commanding a throttle positioned in the air intake of the engine to a fully open position just after the engine has stopped combusting air and fuel (e.g., within 5 seconds) and just before starting the electric compressor (e.g., within 5 seconds).

[0124] In an example in which the engine includes a turbine positioned in an exhaust system of the engine and the turbine is mechanically coupled to a compressor positioned in the intake port upstream of the electric compressor, and further in which the exhaust system includes a wastegate passage configured to direct fluid flow around the turbine when a wastegate positioned in the wastegate passage is open, the method may include commanding the wastegate to fully open after the engine stops combusting air and fuel and just prior to starting the electric compressor.

[0125] In an example of the method, activating the electric compressor to direct the airflow through the first single cylinder may also include anticipating or predicting a duration of the start / stop event sufficient to reduce a temperature of the first single cylinder to the desired temperature prior to requesting to restart the engine.

[0126] In another example of the method, starting the electric compressor may further include starting the electric compressor to a speed or power level that is dependent on one or more of the temperature of the first single cylinder and / or an ambient temperature.

[0127] In yet another example of the method, reducing the temperature of the first single cylinder may occur in response to an indication that the first single cylinder is overheating, and in response to an indication that the second single cylinder is overheating, the method may include selecting whether to sequentially cool the first single cylinder and the second single cylinder during the start / stop event, or alternatively whether to perform general cooling operations. In one example, whether to sequentially cool the first single cylinder and the second single cylinder or whether to perform the general engine cooling operations is selected based on the state of charge of the onboard energy storage device. In addition, the general cooling operations may involve activating the electric compressor to direct another airflow through the engine when the engine is rotating via the motor without fuel supply.

[0128] Figures 3 to 5 The flowchart may further implement another method, which includes, in a first operating condition indicating that a first temperature of a single cylinder of the engine is higher than a first threshold cylinder temperature, operating the engine in a first mode by starting an electric air compressor positioned in the engine intake upstream of a charge air cooler to direct a first airflow through the single cylinder but not through other cylinders of the engine. In a second operating condition indicating that a second temperature of the engine as a whole is higher than a first threshold engine temperature, the method may include operating the engine in a second mode by starting the electric air compressor to direct a second airflow through all cylinders of the engine. For example, in the first mode, directing the first airflow through the single cylinder may be to reduce the first temperature to a second threshold cylinder temperature, and wherein directing the second airflow through all cylinders is to reduce the second temperature to a second threshold engine temperature.

[0129] The method may also include operating the engine in a first mode and a second mode during a start / stop event in which the engine stops burning air and fuel. In one example, operating the engine in the first mode and the second mode may also include predicting that the start / stop event has an indication of a duration, during which, before requesting to restart the engine to burn air and fuel, it is expected or predicted that the engine is operated in the first mode to reduce the first temperature of a single cylinder to a second threshold cylinder temperature, or it is expected that the engine is operated in the second mode to reduce the second temperature of the engine to a second threshold engine temperature. The first operating condition and the second operating condition may be identified before the start / stop event and when the engine is operated to burn air and fuel, and wherein in the first operating condition and / or the second operating condition, a mitigation action is taken before the start / stop event. Such mitigation action may include starting one or more cooling fans to direct cold air toward the engine and / or stopping fuel injection to a single cylinder in the first operating condition. Such mitigation action may also include starting one or more cooling fans in the second operating condition and / or sequentially stopping and then resuming fuel injection to each of all cylinders of the engine in a cyclic manner.

[0130] The method may also include commanding a throttle valve positioned in the air intake downstream of the electric air compressor to a fully open position to operate the engine in both the first mode and the second mode. Additionally, where the engine includes a wastegate positioned in the engine exhaust system, the method may include commanding the wastegate to be opened to a fully open position to operate the engine in both the first mode and the second mode.

[0131] Further, the method may include positioning a single cylinder in a first mode so that a first intake valve and a first exhaust valve coupled to the single cylinder are both in an at least partially open configuration, and may include rotating the engine without fuel via a motor in a second mode, wherein rotating the engine involves opening and closing the intake valve and exhaust valve of each cylinder coupled to the engine.

[0132] Now turn Figure 6 , showing a single engine cylinder cooling operation (described above with respect to Figure 5Detailed discussion of the exemplary timeline 600 of FIG. 6A and FIG. 6B shows an exemplary timeline 600 of FIG. 6B (discussed in detail in FIG. 6B ). The timeline 600 includes a curve 605 indicating whether fuel injection to the engine cylinders is turned on or off over time. The timeline 600 also includes curves 610, 615, 620, and 625 indicating the temperature of the first cylinder, the second cylinder, the third cylinder, and the fourth cylinder, respectively. Thus, it should be understood that this exemplary timeline may refer to a vehicle having a four cylinder engine. A first threshold cylinder temperature is indicated for each cylinder, specifically represented by lines 611, 616, 621, and 626. In this exemplary timeline, it should be understood that the first threshold cylinder temperature is the same between cylinders, but in other examples, the first threshold cylinder temperature may be different between cylinders. It should also be understood that if the temperature of a particular cylinder rises above the first threshold temperature, then the particular cylinder may be indicated as being positively overheated. In this exemplary timeline, the second cylinder is overheated (discussed below) and thus the second threshold cylinder temperature is represented by line 617.

[0133] Timeline 600 also includes a curve 630 that indicates whether an S / S event is indicated over time. Timeline 600 also includes a curve 635 that indicates the position of the intake throttle (e.g., 20) over time. Timeline 600 also includes a curve 640 that indicates the exhaust valve state of the second cylinder, and a curve 645 that indicates the intake valve state of the second cylinder. It should be understood that only cylinder 2 is shown because this particular cylinder is indicated as being overheated, as will be discussed in detail below. Timeline 600 also includes a curve 650 that indicates whether the electric supercharger (e.g., 155) is turned on or off over time. Timeline 600 also includes a curve 655 that indicates whether an engine start is requested over time.

[0134] At time t0, the vehicle's engine is in operation (curve 605) when fuel is injected into the engine cylinders. Each of the first to fourth cylinders is not indicated as being in an overheated state because each cylinder is below its respective first threshold cylinder temperature. No S / S event is indicated (curve 630), and the throttle position (curve 635) is based on driver demand. The electric supercharger is not in operation (curve 650), and while the engine is in operation, no engine start request is indicated (curve 655).

[0135] Between time t0 and t1, it will be appreciated that each of the intake / exhaust valves of each cylinder opens and closes according to different strokes of the engine cycle. However, only the intake valve state and exhaust valve state of the second cylinder are shown (curves 645 and 640, respectively). Shown for the second cylinder valve state are the states of the intake and exhaust valves according to a particular stroke of the engine cycle. The engine cycle includes an exhaust stroke (E), an intake stroke (I), a compression stroke (C), and a power stroke (P). Shown between time t0 and t1, the intake and exhaust valves open and close according to the engine cycle stroke.

[0136] At time t1, the temperature of the second cylinder rises to above the first threshold cylinder temperature. In other words, at time t1, it is indicated that the second cylinder includes an overheating condition. Therefore, in the event that the second cylinder is indicated as being overheated, a single engine cylinder cooling operation is scheduled for the next S / S event. For example, such scheduling may be performed by a controller. Although not explicitly shown, mitigation actions may be taken between times t1 and t2 to attempt to reduce the temperature of the second cylinder. Such examples may include stopping fuel injection into the second cylinder, starting a cooling fan, and the like. In this example, it should be understood that the cooling fan is started between times t1 and t2, although other strategies as discussed above may be performed without departing from the scope of the present disclosure.

[0137] At time t2, an S / S event is indicated. Therefore, fuel injection to the engine cylinder is stopped (curve 605). In addition, in the event that an S / S event is indicated, the throttle is controlled to a fully open position (curve 635). It should also be understood that at time t2, it is indicated that the conditions for performing a single engine cylinder cooling operation (discussed in detail with respect to step 502 of method 500) are satisfied. Although not explicitly shown, in an example where the vehicle system includes a wastegate, in response to indicating that the conditions are satisfied, the wastegate may be commanded to open at time t2.

[0138] In the event that the condition is satisfied at t2, the engine may be controlled to position the intake and exhaust valves corresponding to the overheated cylinder (in this example, the second cylinder) so that both the intake and exhaust valves are at least partially open. As discussed above, actuators such as a first oil pressure-controlled actuator (e.g., 283) and a second oil pressure-controlled actuator (e.g., 284) associated with an intake camshaft (e.g., 281) and an exhaust camshaft (e.g., 282), respectively, may be actuated via a controller to position the engine so that the intake and exhaust valves for the second cylinder are at least partially open. In some examples, this action may be performed when the engine is rotating to a standstill, while in other examples, a motor may be used to assist or control the engine to rotate to a position where the intake and exhaust valves corresponding to the second cylinder are at least partially open. Thus, at time t3, the intake valve (curve 645) and the exhaust valve (curve 640) are so positioned.

[0139] With the conditions for individual engine cylinder cooling operation met, and with the throttle commanded open (and the wastegate, where included, commanded open), the electric supercharger is commanded on at time t3. As discussed, the electric supercharger may be controlled to a predetermined speed and / or a predetermined power level, or in some examples, the speed / power level may be a function of the degree of cylinder overheating, and may therefore further be a function of ambient temperature, mass air flow through the engine totaled in the current drive cycle, etc.

[0140] With the electric supercharger activated at time t3, air may be directed through the CAC (eg, 118), thereby directing cool air through the overheated cylinder, thereby acting to cool the overheated cylinder. Thus, between time t3 and t4, the temperature of the second cylinder begins to drop (curve 615).

[0141] At time t4, the temperature of the second cylinder reaches a second threshold cylinder temperature represented by line 617. In the event that the second cylinder temperature has been reduced to the second threshold cylinder temperature via the cooling operation, the electric supercharger is deactivated (curve 650). Although not explicitly shown, if the wastegate was commanded open for the cooling operation, the wastegate may be commanded closed at time t4. The temperature of the second cylinder continues to be monitored between time t4 and t5, and the temperature remains below the first threshold cylinder temperature.

[0142] At time t5, an engine restart is requested (curve 655). Although not explicitly shown, restarting the engine may include a starter motor or electric machine rotating the engine to a predetermined speed and then starting fuel injection (and spark). Therefore, in the case of requesting an engine restart, it should be understood that the starter motor or electric machine is used to begin rotating the engine between time t5 and t6, and at time t6, fuel injection (and spark) is provided (curve 605). In the case where the engine begins to rotate at time t5, the second cylinder intake valve and exhaust valve begin to operate. Between time t6 and t7, the vehicle is propelled via the engine, and the throttle position changes according to the driver's demand.

[0143] Now turn Figure 7 , shown for general engine cooling operation (described above with respect to Figure 4 Detailed discussion) of the exemplary timeline 700. Timeline 700 includes curve 705, which indicates whether fuel injection is provided to the engine (on) or not provided to the engine (off) over time. Timeline 700 also includes curve 710, which indicates the engine temperature (general engine temperature) over time. Line 711 represents a first threshold engine temperature, wherein if the engine temperature is at or above the first threshold engine temperature, it should be understood that the engine is overheated. Line 712 represents a second threshold engine temperature, which, if reached during the general engine cooling operation, can result in the termination of the general cooling operation because the desired result of cooling the engine to the second threshold engine temperature has been achieved. Timeline 700 also includes curve 715, which indicates whether S / S events are indicated over time. Timeline 700 also includes curve 720, which indicates whether the intake throttle (e.g., 20) is opened or closed (or at a position therebetween) over time. Timeline 700 also includes curve 725, which indicates the state of the motor (e.g., 52) over time. Timeline 700 also includes a curve 730 indicating engine speed (engine RPM) over time. Timeline 700 also includes a curve 735 indicating the state of an electric supercharger (eg, 155) over time. Timeline 700 also includes a curve 740 indicating whether an engine start is requested over time.

[0144] At time t0, the engine is in operation and fuel is provided to the engine cylinders (curve 705). In other words, the vehicle is propelled via the engine. The motor is off (curve 725), the electric supercharger is off (curve 735) and no engine start is requested while the engine is in operation (curve 740). At time t0, the engine temperature (curve 710) is below the first threshold engine temperature and therefore the engine is not indicated as overheated. No S / S event is indicated (curve 715).

[0145] Between time t0 and t1, throttle position (curve 720) and engine speed (curve 730) vary according to driver demand. At time t1, when the engine temperature has risen to the first threshold engine temperature, an engine overheat state (curve 710) is indicated. Therefore, between time t1 and t2, although not explicitly shown, it should be understood that mitigation actions including starting one or more cooling fans are taken to reduce the engine temperature. In some examples (not shown here), mitigation actions may include performing a cyclic cooling operation, which involves cutting off the fuel to one cylinder at a time while maintaining the intake and exhaust valves open to pump cold air through the engine. However, in this exemplary timeline, the cooling fan should be understood to be started.

[0146] With the engine overheat condition identified at time t1, a general engine cooling operation is scheduled for the next S / S event. At time t2, the next S / S event is requested (curve 715). Therefore, fuel injection to the engine cylinders is stopped (curve 705). Between times t2 and t3, it will be appreciated that the conditions for performing a general engine cooling operation (discussed in detail above with respect to step 402 of method 400) are indicated to be met.

[0147] Under conditions for general engine cooling operation, at time t3, the throttle is commanded to a fully open position (curve 720) and the motor is started (curve 725) to rotate the engine without fuel. Thus, between times t3 and t4, the engine RPM increases as the motor is used to rotate the engine. It should be understood that the intake and exhaust valves operate to open and close as the engine rotates. Although not explicitly shown, in some examples where the vehicle includes a wastegate (e.g., 91), the wastegate may be commanded to a fully open position.

[0148] In this example, the engine is rotated to achieve a predetermined speed. The predetermined speed may be based on engine temperature, ambient temperature, air mass accumulated in the current drive cycle before the current S / S event, etc. With the engine rotating without fuel, at time t4, the electric supercharger is activated. Although not explicitly shown, the electric supercharger is controlled to a predetermined speed or a predetermined power level. In some examples, such a predetermined speed and / or power level may be a function of engine temperature, ambient temperature, air mass accumulated in the current drive cycle, etc.

[0149] With the electric supercharger activated, air is directed through the CAC (e.g., 118), thereby directing cool air through the engine that is spinning without fuel. Although not explicitly shown, it is understood that the engine is rotated so that it rotates in the same direction as when the engine burns air and fuel. This rotation creates a vacuum in the intake and pressure in the exhaust, and thus assists in drawing air from the electric supercharger through the engine. Therefore, between time t4 and t5, the engine temperature decreases.

[0150] At time t5, the engine temperature (curve 710) reaches the second threshold engine temperature (curve 712). Therefore, the motor is deactivated via the controller (curve 725) and the electric supercharger is turned off via the controller (curve 735). Therefore, between time t5 and t6, the engine rotates to rest (curve 730). The engine temperature continues to be monitored between time t5 and t6, and the temperature remains below the first threshold engine temperature so that no additional engine cooling is requested.

[0151] At time t6, an engine start is requested (curve 740) and the motor (curve 725) is therefore used to rotate the engine. Therefore, the engine speed increases between time t6 and t7 (curve 730), and fuel is provided to the engine at time t7 (curve 705) while the motor is deactivated (curve 725). Between time t7 and t8, the throttle position and engine RPM may vary according to driver demand while the engine is burning air and fuel.

[0152] In this way, if an overheated engine condition is identified, depending on whether the overheated engine condition is limited to a single engine cylinder (or multiple cylinders in some examples) or the engine as a whole, an effective strategy can be selected to mitigate the overheated engine condition, which can effectively cool the single engine cylinder or the engine as a whole while effectively utilizing the power stored in the onboard energy storage device. In doing so, engine degradation due to the overheated condition can be reduced or avoided.

[0153] The technical effect is to recognize that under the condition that the engine of a hybrid vehicle stops burning air and fuel under a start / stop event, the temperature of the engine and the engine cylinders may continue to rise, and this further rise may cause engine degradation in the case of indicating that one or more cylinders of the engine as a whole are overheated. Therefore, a further technical effect is to recognize that in some examples, it may be more energy-efficient to cool a single engine cylinder or multiple cylinders one at a time in a sequential manner, while in other examples, it may be desirable to cool all engine cylinders. A further technical effect is to recognize that under the condition that the engine stops burning air and fuel, an electric air compressor positioned in the engine intake can be used to provide cooling airflow to the engine or one or more independent engine cylinders. A further technical effect is to recognize that such cooling airflow can be increased in this case, wherein the intake throttle and wastegate are commanded to be fully open when the electric air compressor is activated. By adopting the above-mentioned technical effects associated with the systems and methods discussed herein, engine degradation can be reduced or avoided in response to an engine overheating condition for a vehicle configured with start / stop capability.

[0154] In this article and references Figure 1 to Figure 2 The system described herein and referenced Figures 3 to 5The described method may implement one or more systems and one or more methods. In one example, a method includes: starting an electric compressor in an intake of a vehicle engine during a start / stop event in which the engine is not burning air and fuel to direct airflow through a first single cylinder of the engine so as to reduce the temperature of the first single cylinder to a desired temperature before requesting to restart the engine. In a first example of the method, the method also includes positioning the first single cylinder so that both an intake valve and an exhaust valve of the first single cylinder are in an at least partially open configuration to direct the airflow through the first single cylinder. A second example of the method optionally includes the first example and also includes wherein positioning the first single cylinder so that both the intake valve and the exhaust valve are in an at least partially open configuration includes adjusting the timing of opening the intake valve and the exhaust valve via controlling the rotation of a first camshaft mechanically coupled to the intake valve and via controlling the rotation of a second camshaft mechanically coupled to the exhaust valve. A third example of the method optionally includes one or more or each of the first to second examples, and further includes commanding a throttle valve positioned in the intake port of the engine to a fully open position just after the engine has stopped burning air and fuel and just before starting the electric compressor. A fourth example of the method optionally includes any one or more or each of the first to third examples, and further includes wherein the engine includes a turbine positioned in an exhaust system of the engine, the turbine mechanically coupled to a compressor positioned in the intake port upstream of the electric compressor, and wherein the exhaust system includes a wastegate passage configured to direct fluid flow around the turbine when a wastegate positioned in the wastegate passage is open; and wherein the wastegate is commanded to a fully open position just after the engine stops burning air and fuel and just before starting the electric compressor. A fifth example of the method optionally includes any one or more or each of the first to fourth examples, and further includes wherein starting the electric compressor to direct the airflow through the first single cylinder further includes an expected or predicted duration of the start / stop event sufficient to reduce the temperature of the first single cylinder to the desired temperature before requesting to restart the engine. A sixth example of the method optionally includes any one or more or each of the first to fifth examples, and further includes wherein starting the electric compressor further includes starting the electric compressor to a speed or power level that is dependent on one or more of the temperature of the first single cylinder and / or an ambient temperature.The seventh example of the method optionally includes one or more or each of the first to sixth examples, and further includes wherein reducing the temperature of the first single cylinder occurs in response to an indication that the first single cylinder is overheating; and in response to an indication that the second single cylinder is overheating, selecting whether to sequentially cool the first single cylinder and the second single cylinder during the start / stop event, or whether to perform general engine cooling operations. The eighth example of the method optionally includes any one or more or each of the first to seventh examples, and further includes wherein selecting whether to sequentially cool the first single cylinder and the second single cylinder or whether to perform the general engine cooling operations is based on the state of charge of the onboard energy storage device. The ninth example of the method optionally includes any one or more or each of the first to eighth examples, and further includes wherein the general engine cooling operations involve activating the electric compressor to direct another airflow through the engine when the engine is rotating via the motor without fuel.

[0155] Another example of a method includes, under a first operating condition indicating that a first temperature of a single cylinder of the engine is above a first threshold cylinder temperature, operating the engine in a first mode by activating an electric air compressor positioned in the engine intake upstream of a charge air cooler to direct a first airflow through the single cylinder but not through other cylinders of the engine; and under a second operating condition indicating that a second temperature of the engine as a whole is above a first threshold engine temperature, operating the engine in a second mode by activating the electric air compressor to direct a second airflow through all cylinders of the engine. In the first example of the method, the method also includes wherein directing the first airflow through the single cylinder in the first mode is to reduce the first temperature to a second threshold cylinder temperature; and wherein directing the second airflow through all cylinders is to reduce the second temperature to a second threshold engine temperature. A second example of the method optionally includes the first example and also includes operating the engine in the first mode and the second mode during a start / stop event in which the engine stops burning air and fuel; and wherein operating the engine in the first mode and the second mode also includes predicting that the start / stop event has an indication of a duration, during which the engine is expected to be operated in the first mode to reduce the first temperature of the single cylinder to the second threshold cylinder temperature, or the engine is expected to be operated in the second mode to reduce the second temperature of the engine to the second threshold engine temperature, before requesting to restart the engine to burn air and fuel. A third example of the method optionally includes any one or more or each of the first to second examples, and also includes identifying the first operating condition and the second operating condition when operating the engine to burn air and fuel, and wherein in the first operating condition and / or the second operating condition, mitigation actions are taken before the start / stop event, the mitigation actions including starting one or more cooling fans to direct cold air toward the engine and / or stopping one or more of injecting fuel into the individual cylinders under the first operating condition; and starting one or more cooling fans and / or sequentially stopping and then resuming fuel injection into each of all the cylinders of the engine in a cyclic manner under the second operating condition.A fourth example of the method optionally includes any one or more or each of the first to third examples, and further includes commanding a throttle valve positioned in the intake port downstream of the electric air compressor to a fully open position so as to operate the engine in both the first mode and the second mode; and, if the engine includes a wastegate positioned in an exhaust system of the engine, commanding the wastegate to be opened to a fully open position so as to operate the engine in both the first mode and the second mode. A fifth example of the method optionally includes any one or more or each of the first to fourth examples, and further includes wherein operating the engine in the first mode further includes positioning the single cylinder so that both a first intake valve and a first exhaust valve coupled to the single cylinder are in an at least partially open configuration; and wherein operating the engine in the second mode further includes rotating the engine without fuel via a motor, and wherein rotating the engine involves opening and closing an intake valve and an exhaust valve coupled to each cylinder of the engine.

[0156] A system for a hybrid vehicle includes an engine, the engine including an intake port and an exhaust port; a plurality of engine cylinders, each cylinder including an intake valve and an exhaust valve; an electric air compressor, the electric air compressor coupled to the intake port upstream of a charge air cooler, the charge air cooler being located upstream of an intake throttle; a first actuator, the first actuator being configured to control rotation of a first camshaft mechanically coupled to the intake valves of the plurality of engine cylinders; a second actuator, the second actuator being configured to control rotation of a second camshaft mechanically coupled to the exhaust valves of the plurality of engine cylinders; a start / stop system, the start / stop system being configured to automatically stop the engine in response to satisfying a set of predetermined operating conditions stop burning air and fuel; and a controller storing instructions in a non-volatile memory, the instructions, when executed, causing the controller to: start the electric air compressor in a start / stop event in which the engine stops burning air and fuel; cause cold air to flow through the single cylinder of the engine under conditions in which a first temperature of the single cylinder is greater than a first threshold cylinder temperature, but in which a second temperature of the engine is less than a first threshold engine temperature; and wherein starting the electric air compressor to cause cold air to flow through the single cylinder also includes commanding the throttle to open to a fully open position, and controlling the first actuator and the second actuator to position the intake valve and exhaust valve of the single cylinder to an at least partially open configuration. In a first example of the system, the system further comprises a wireless communication device; an onboard navigation system; wherein the controller stores additional instructions to: retrieve information related to a predicted duration of the start / stop event via the wireless communication device and / or the onboard navigation system; and at the start / stop event, in response to predicting that the duration of the start / stop event is greater than the amount of time predicted to reduce the first temperature of the single cylinder to a desired temperature, start the electric air compressor to flow cool air through the single cylinder. A second example of the system optionally includes the first example, and further comprises a turbine positioned in the exhaust port, the turbine mechanically coupled to a mechanically driven compressor positioned upstream of the electric air compressor; a wastegate passage including an actuable wastegate, the wastegate passage being configured to direct fluid flow around the turbine under conditions when the actuable wastegate is open; and wherein the controller stores additional instructions to command opening of the wastegate at the start / stop event and just prior to starting the electric air compressor.A third example of the system optionally includes any one or more or each of the first to second examples and further includes a motor configured to rotate the engine; and wherein the controller stores additional instructions to start the electric air compressor and, under the condition that the second temperature of the engine is greater than the first threshold engine temperature, rotate the engine without fuel to cool the multiple engine cylinders rather than flowing cool air through the single cylinder.

[0157] Note that the exemplary control and estimation routines included herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller in combination 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. Thus, the various actions, operations, or functions shown can be performed in the order shown, in parallel, or omitted in some cases. Similarly, the processing order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations, and / or functions shown can be repeatedly performed depending on the specific strategy used. In addition, the actions, operations, and / or functions can be graphically represented as codes in a non-transitory memory of a computer-readable storage medium programmed into an engine control system, wherein the actions are performed by executing instructions in a system including various engine hardware components in combination with an electronic controller.

[0158] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and these specific embodiments should not be viewed in a limiting sense, as many variations are possible. For example, the above-described techniques can be applied to V-6, I-4, I-6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0159] The following claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or a "first" element or the equivalent thereof. Such claims should be understood to include incorporation of one or more such elements, thereby neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, the same, or different in scope to the original claims, are deemed to be included in the subject matter of the present disclosure.

[0160] According to the present invention, a method is provided, comprising: activating an electric compressor in an air intake of a vehicle engine during a start / stop event in which the engine is not combusting air and fuel to direct air flow through a first single cylinder of the engine to reduce the temperature of the first single cylinder to a desired temperature prior to requesting to restart the engine.

[0161] According to an embodiment, a method is provided that includes positioning the first single cylinder such that both an intake valve and an exhaust valve of the first single cylinder are in an at least partially open configuration to direct the airflow through the first single cylinder.

[0162] According to an embodiment, a method is provided, comprising: positioning the first single cylinder so that both the intake valve and the exhaust valve are in an at least partially open configuration including adjusting the timing of opening the intake valve and the exhaust valve via controlling the rotation of a first camshaft mechanically coupled to the intake valve and via controlling the rotation of a second camshaft mechanically coupled to the exhaust valve.

[0163] According to an embodiment, a method is provided that includes commanding a throttle valve positioned in the air intake of the engine to a fully open position just after the engine has stopped combusting air and fuel and just before starting the electric compressor.

[0164] According to an embodiment, a method is provided, comprising: the engine includes a turbine positioned in an exhaust system of the engine and the turbine is mechanically connected to a compressor positioned in the intake port upstream of the electric compressor, and wherein the exhaust system includes a wastegate passage, the wastegate passage being configured to direct fluid flow around the turbine when a wastegate positioned in the wastegate passage is opened; and wherein the wastegate is commanded to a fully open position just after the engine stops burning air and fuel and just before starting the electric compressor.

[0165] According to an embodiment, a method is provided, comprising: activating the electric compressor to direct the airflow through the first single cylinder further comprising anticipating or predicting that the duration of the start / stop event is sufficient to reduce the temperature of the first single cylinder to the desired temperature before requesting to restart the engine.

[0166] According to an embodiment, a method is provided, comprising: starting the electric compressor further comprising starting the electric compressor to a speed or power level dependent on one or more of the temperature of the first single cylinder and / or an ambient temperature.

[0167] According to an embodiment, a method is provided, comprising: reducing the temperature of the first single cylinder occurs in response to an indication that the first single cylinder is overheating, and in response to an indication that the second single cylinder is overheating, selecting whether to cool the first single cylinder and the second single cylinder sequentially during a start / stop event, or whether to perform a general cooling operation instead.

[0168] According to an embodiment, a method is provided, which includes: selecting whether to sequentially cool the first single cylinder and the second single cylinder or whether to perform the general engine cooling operation according to the state of charge of an onboard energy storage device.

[0169] According to an embodiment, a method is provided comprising: the general engine cooling operation involves activating the electric compressor to direct another air flow through the engine when the engine is rotating via a motor without fuel.

[0170] According to the present invention, a method is provided, which includes: under a first operating condition indicating that a first temperature of a single cylinder of the engine is higher than a first threshold cylinder temperature, operating the engine in a first mode by starting an electric air compressor positioned in an air intake of the engine upstream of a charge air cooler to direct a first airflow through the single cylinder but not through other cylinders of the engine; and under a second operating condition indicating that a second temperature of the engine as a whole is higher than a first threshold engine temperature, operating the engine in a second mode by starting the electric air compressor to direct a second airflow through all cylinders of the engine.

[0171] According to an embodiment, a method is provided, comprising: directing the first airflow through the single cylinder in the first mode is to reduce the first temperature to a second threshold cylinder temperature; and wherein directing the second airflow through all cylinders is to reduce the second temperature to a second threshold engine temperature.

[0172] According to an embodiment, a method is provided, comprising: operating the engine in the first mode and the second mode during a start / stop event in which the engine stops burning air and fuel; and wherein operating the engine in the first mode and the second mode also includes predicting that the start / stop event has an indication of a duration, during which, before requesting to restart the engine to burn air and fuel, it is expected that the engine is operated in the first mode to reduce the first temperature of the single cylinder to the second threshold cylinder temperature, or it is expected that the engine is operated in the second mode to reduce the second temperature of the engine to the second threshold engine temperature.

[0173] According to an embodiment, a method is provided, comprising: when operating the engine to burn air and fuel, identifying the first operating condition and the second operating condition, and wherein in the first operating condition and / or the second operating condition, taking mitigation actions before the start / stop event, the mitigation actions comprising starting one or more cooling fans to direct cold air toward the engine and / or stopping one or more of injecting fuel into the individual cylinders under the first operating condition; and starting one or more cooling fans under the second operating condition and / or sequentially stopping in a cyclic manner and then resuming fuel injection into each of all the cylinders of the engine.

[0174] According to an embodiment, a method includes: commanding a throttle valve positioned in the intake port downstream of the electric air compressor to a fully open position so as to operate the engine in both the first mode and the second mode; and under the condition that the engine includes a waste valve positioned in the exhaust system of the engine, commanding the waste valve to be opened to a fully open position so as to operate the engine in both the first mode and the second mode.

[0175] According to an embodiment, a method is provided, comprising: operating the engine in the first mode further comprises positioning the single cylinder so that both a first intake valve and a first exhaust valve connected to the single cylinder are in an at least partially open configuration; and wherein operating the engine in the second mode further comprises rotating the engine without fuel via a motor, and wherein rotating the engine involves opening and closing the intake valve and exhaust valve of each cylinder connected to the engine.

[0176] According to the present invention, a system for a hybrid vehicle is provided, which comprises: an engine, the engine comprising an intake port and an exhaust port; a plurality of engine cylinders, each cylinder comprising an intake valve and an exhaust valve; an electric air compressor, the electric air compressor being coupled to the intake port upstream of a charge air cooler, the charge air cooler being located upstream of an intake throttle valve; a first actuator, the first actuator being configured to control the rotation of a first camshaft mechanically coupled to the intake valves of the plurality of engine cylinders; a second actuator, the second actuator being configured to control the rotation of a second camshaft mechanically coupled to the exhaust valves of the plurality of engine cylinders; a start / stop system, the start / stop system being configured to cause the engine to rotate in response to a set of predetermined operating conditions being satisfied. The engine automatically stops burning air and fuel; and a controller storing instructions in a non-volatile memory, which, when executed, causes the controller to: start the electric air compressor in a start / stop event in which the engine stops burning air and fuel; cause cold air to flow through the single cylinder of the engine under conditions in which a first temperature of the single cylinder is higher than a first threshold cylinder temperature, but in which a second temperature of the engine is lower than the first threshold engine temperature; and wherein starting the electric air compressor to cause cold air to flow through the single cylinder also includes commanding the throttle to open to a fully open position, and controlling the first actuator and the second actuator to position the intake valve and exhaust valve of the single cylinder to an at least partially open configuration.

[0177] According to an embodiment, the present invention is further characterized by a wireless communication device; an onboard navigation system; wherein the controller stores additional instructions to: retrieve information related to the predicted duration of the start / stop event via the wireless communication device and / or the onboard navigation system; and under the start / stop event, in response to a prediction that the duration of the start / stop event is greater than the predicted amount of time to reduce the first temperature of the single cylinder to the desired temperature, start the electric air compressor to flow cool air through the single cylinder.

[0178] According to an embodiment, the present invention is further characterized by a turbine positioned in the exhaust port, the turbine being mechanically coupled to a mechanically driven compressor positioned upstream of the electric air compressor; a wastegate passage including an actuable wastegate, the wastegate passage being configured to direct fluid flow around the turbine under conditions when the actuable wastegate is open; and wherein the controller stores additional instructions to command opening of the wastegate at the start / stop event and just prior to starting the electric air compressor.

[0179] According to an embodiment, the present invention is further characterized by a motor configured to rotate the engine; and wherein the controller stores additional instructions to start the electric air compressor and, under the condition that the second temperature of the engine is greater than the first threshold engine temperature, rotate the engine without fuel to cool the multiple engine cylinders instead of flowing cool air through the single cylinder.

Claims

1. A method for an engine, wherein include: activating an electric compressor in an air intake of an engine of a vehicle during a start / stop event in which the engine is not combusting air and fuel to direct air flow through a first single cylinder of the engine to reduce a temperature of the first single cylinder to a desired temperature prior to requesting to restart the engine, wherein reducing the temperature of the first single cylinder occurs in response to an indication that the first single cylinder is overheated; as well as In response to an indication of overheating of the second single cylinder, a selection is made as to whether to sequentially cool the first single cylinder and the second single cylinder or to perform a general engine cooling operation during the start / stop event, wherein the selection as to whether to sequentially cool the first single cylinder and the second single cylinder or to perform the general engine cooling operation is based on a state of charge of an onboard energy storage device, and wherein the general engine cooling operation involves starting the electric compressor to direct another airflow through the engine when the engine is rotating via a motor without fuel supply. 2 . The method of claim 1 , further comprising positioning the first single cylinder such that both an intake valve and an exhaust valve of the first single cylinder are in an at least partially open configuration to direct the airflow through the first single cylinder.

3. The method of claim 2, wherein positioning the first single cylinder so that both the intake valve and the exhaust valve are in the at least partially open configuration includes adjusting the timing of opening the intake valve and the exhaust valve via controlling rotation of a first camshaft mechanically coupled to the intake valve and via controlling rotation of a second camshaft mechanically coupled to the exhaust valve.

4. The method of claim 1 further comprising commanding a throttle valve positioned in the air intake of the engine to a fully open position just after the engine has stopped combusting air and fuel and just before starting the electric compressor.

5. The method of claim 1 , wherein the engine includes a turbine positioned in an exhaust system of the engine, the turbine mechanically coupled to a compressor positioned in the intake upstream of the electric compressor, and wherein the exhaust system includes a wastegate passage configured to direct fluid flow around the turbine when a wastegate positioned in the wastegate passage is open; and Wherein the wastegate is commanded to a fully open position just after the engine has stopped combusting air and fuel and just before starting the electric compressor.

6. The method of claim 1 wherein activating the electric compressor to direct the airflow through the first single cylinder further comprises anticipating or predicting a duration of the start / stop event sufficient to reduce the temperature of the first single cylinder to the desired temperature prior to the request to restart the engine.

7. The method of claim 1, wherein starting the electric compressor further comprises starting the electric compressor to a speed or power level that is dependent on one or more of the temperature of the first single cylinder and / or an ambient temperature.

8. A system for a hybrid vehicle, wherein include: an engine, the engine comprising an air intake and an exhaust; a plurality of engine cylinders, each cylinder including an intake valve and an exhaust valve; an electric air compressor coupled to the air intake upstream of a charge air cooler located upstream of an intake throttle; a first actuator configured to control rotation of a first camshaft mechanically coupled to the intake valves of the plurality of engine cylinders; a second actuator configured to control rotation of a second camshaft mechanically coupled to the exhaust valves of the plurality of engine cylinders; a start / stop system configured to automatically stop the engine from combusting air and fuel in response to a set of predetermined operating conditions being met; and a controller storing instructions in a non-transitory memory, the instructions, when executed, causing the controller to: activating the electric air compressor at a start / stop event in which the engine stops combusting air and fuel to flow cool air through the single cylinder of the engine under conditions in which a first temperature of the single cylinder is above a first threshold cylinder temperature, but in which a second temperature of the engine is below the first threshold engine temperature; and Wherein activating the electric air compressor to flow cool air through the single cylinder further includes commanding the throttle to open to a fully open position and controlling the first actuator and the second actuator to position the intake valve and the exhaust valve of the single cylinder to an at least partially open configuration.

9. The system of claim 8, further comprising: include: Wireless communication devices; In-car navigation system; wherein the controller stores further instructions to: retrieving, via the wireless communication device and / or the onboard navigation system, information regarding a predicted duration of the start / stop event; and During the start / stop event, in response to a duration of the start / stop event being predicted to be greater than an amount of time predicted to reduce the first temperature of the single cylinder to a desired temperature, activating the electric air compressor to flow cool air through the single cylinder.

10. The system of claim 8, further comprising: include: a turbine positioned in the exhaust port, the turbine mechanically coupled to a mechanically driven compressor positioned upstream of the electric air compressor; a wastegate passage including an actuatable wastegate, the wastegate passage being configured to direct fluid flow around the turbine under conditions when the actuatable wastegate is open; and Wherein the controller stores additional instructions to command opening of the wastegate at a start / stop event and just prior to activating the electric air compressor.

11. The system of claim 8, further comprising: include: a motor configured to rotate the engine; and The controller stores additional instructions to command fully opening the throttle, starting the electric air compressor, and, under the condition where the second temperature of the engine is greater than the first threshold engine temperature, spinning the engine without fuel to cool the multiple engine cylinders during the start / stop event rather than flowing cool air through the single cylinder.

12. The system of claim 11, further comprising: include: one or more cooling fans configured to direct cool air toward the engine; and wherein the controller stores further instructions to take mitigation actions prior to the start / stop event, the mitigation actions comprising activating the one or more cooling fans after the second temperature of the engine is greater than the first threshold engine temperature and sequentially stopping fuel supply to each of the plurality of engine cylinders and then resuming fuel supply to each of the plurality of engine cylinders in a cyclic manner; and The mitigation action includes starting the one or more cooling fans and / or stopping fuel injection to the single cylinder prior to the start / stop and in response to the first temperature of the single cylinder being higher than the first threshold cylinder temperature, but wherein the second temperature of the engine is lower than the first threshold engine temperature.

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