Particulate filter regeneration system and method

Abstract

Exhaust particulate filter regeneration systems and methods during engine non-combustion conditions are provided. In one example, a method can include, in response to soot loading on the PF above a first threshold and a PF temperature above a threshold, regenerating the PF by flowing compressed air through the PF via operation of an electrically powered booster coupled to the intake manifold.

Description

Technical Field

[0001] This specification relates in its entirety to methods and systems for regenerating particulate filters during non-combustion periods of an engine. Background Technology

[0002] Combustion in gasoline-powered engines produces particulate matter (PM) (such as soot and aerosols) that can be emitted into the atmosphere. To achieve emissions compliance, engine exhaust systems may include particulate filters (PFs) to filter out exhaust PM before it is released into the atmosphere. These devices can be regenerated periodically or opportunistically during engine operation to reduce the amount of captured particulate matter. Regeneration is typically achieved by raising the temperature of the PF to a predetermined level for a sustained period while passing a defined composition of exhaust gas through the PF to burn or oxidize the captured particulate matter. During engine start-stop (idle stop), deceleration fuel cut-off (DFSO) conditions, and vehicle operation using electric motor torque, there may not be sufficient time for PF regeneration to complete.

[0003] Various methods have been provided for regenerating the power filter (PF) during engine shutdown. In one example, as shown in US 8,844,272, Bidner et al. disclosed a method for operating a vacuum pump coupled to the engine intake manifold to draw ambient air through the engine exhaust manifold during engine shutdown. When the temperature of the PF is above a threshold temperature, oxygen in the ambient air flowing through the PF can facilitate PF regeneration during engine shutdown.

[0004] However, the inventors of this paper have recognized the potential drawbacks of the aforementioned method. As an example, operating the intake vacuum pump to draw ambient air from the exhaust manifold can be a time-consuming process due to the extended time required to establish a vacuum in the exhaust manifold. High-power pumps may be needed to remove air from the exhaust system and EGR passages to create a vacuum. When sufficient oxygen from the ambient air reaches the PF, the temperature of the exhaust passages, including the PF, may drop below the threshold temperature required for PF regeneration. Incomplete PF regeneration can result in higher-than-expected PM residues on the PF, increasing exhaust back pressure, which can adversely affect engine performance during subsequent engine cycles. Summary of the Invention

[0005] The inventors of this paper have identified a system and method for solving the problems described above. An exemplary method includes: during a non-combustion state of an engine coupled to a vehicle, in response to a soot load exceeding a first threshold and a PF temperature exceeding a threshold temperature required for soot oxidation in the presence of oxygen, activating an electric booster in the engine's intake system to direct compressed air to the PF for PF regeneration. In this way, by operating the electric booster during the engine's non-combustion state, starting power can be provided to direct compressed air through the PF for PF regeneration.

[0006] In one example, the power supply (PF) can be regenerated opportunistically during engine non-combustion conditions. The engine may be a turbocharged engine comprising a turbine-driven intake compressor and an electrically driven intake compressor (also referred to herein as a battery-operated electric booster), which selectively operates to provide additional boost during periods of increased torque demand. PF regeneration can be initiated if, during engine non-combustion conditions, engine start-stop conditions, deceleration fuel cut-off (DFSO) conditions, and vehicle operation periods using electric motor torque, the estimated PM load on the PF is above a threshold load and the temperature of the exhaust passage including the PF is above a threshold temperature. The intake throttle can be actuated to a fully open position, and the electric booster can be activated to allow compressed ambient air to flow from the engine intake passage to the PF. An exhaust gas recirculation (EGR) valve coupled to the EGR passage can be opened, and an exhaust gas valve coupled to the wastegate passage can also be opened to facilitate the flow of compressed air from the intake manifold to the exhaust manifold. At elevated temperatures, in the presence of oxygen from the compressed air, the PM can combust and the PF can be regenerated. The compressed air flow can provide starting power to allow heated air to flow from the exhaust catalyst, which is connected upstream of the PF to the exhaust passage, to the PF to further accelerate regeneration. The flow of compressed air can continue until PF regeneration is complete, the PF temperature drops below a threshold temperature, and one or more combustion events occur in the engine.

[0007] In this way, by opportunistically utilizing existing engine components such as electric boosters, particulate filter regeneration can be performed even during engine non-combustion periods, eliminating the need for additional engine components. By using electric boosters, compressed air with a high oxygen content can be supplied to the particulate filter (PF) for a short period after the engine is turned off. The technical advantage of performing particulate filter regeneration during engine-off periods is that, for hybrid vehicles with short engine operating times, a clean PF can be maintained, thereby improving emissions quality and engine performance. In this way, residual waste heat can be optimally used for PF regeneration.

[0008] It should be understood that the foregoing summary is intended to present a simplified version of a series of concepts that will be further described in the detailed description section. This does not imply the identification of key or essential features of the claimed subject matter, the scope of which is uniquely defined by the claims following the detailed description. Furthermore, the claimed subject matter is not limited to solutions to any of the shortcomings pointed out above or in any part of this disclosure. Attached Figure Description

[0009] Figure 1 An exemplary hybrid vehicle system including a particulate filter (PF) is schematically shown.

[0010] Figure 2 A flowchart is shown illustrating an exemplary method that can be implemented to regenerate PF during engine non-combustion conditions.

[0011] Figure 3 An exemplary operation of an electric booster for PF regeneration is shown. Detailed Implementation

[0012] The following description relates to systems and methods for regenerating an exhaust particulate filter (PF) during engine non-combustion conditions. Such methods may include flowing compressed air through the PF, which is coupled to… Figure 1 The hybrid vehicle system depicted in the image. The engine controller can be configured to execute control programs, such as... Figure 3 The example program is used to regenerate PF opportunistically. Figure 3 An exemplary electric booster operation for achieving PF regeneration is shown.

[0013] Figure 1 A schematic diagram 101 of a vehicle system 102 is shown, which has an example engine system 100 including an engine 10. In one example, engine system 100 may be a diesel engine system. In another example, engine system 100 may be a gasoline engine system. In the depicted embodiment, engine 10 is a turbocharged engine coupled to a turbocharger 15, which includes a compressor 114 driven by a turbine 116. Specifically, fresh air is introduced into engine 10 via an air purifier 112 along intake passage 42 and flows to compressor 114. The compressor may be any suitable intake compressor, such as a motor-driven or drive shaft-driven supercharger compressor. In engine system 10, the compressor is a turbocharger compressor mechanically coupled to turbine 116 via shaft 19, turbine 116 being driven by expanding engine exhaust.

[0014] like Figure 1As shown, compressor 114 is connected to throttle valve 20 via supercharged air cooler (CAC) 118. Throttle valve 20 is connected to engine intake manifold 22. Compressed air flows from compressor through supercharged air cooler 118 and throttle valve 20 to intake manifold 22. Figure 1 In the illustrated embodiment, the pressure of the air intake within the intake manifold 22 is sensed by the manifold air pressure (MAP) sensor 124. The temperature of the ambient air entering the intake passage 42 can be estimated via the intake air temperature (IAT) sensor 51.

[0015] One or more sensors may be connected to the inlet of compressor 114. For example, temperature sensor 55 may be connected to the inlet to estimate compressor inlet temperature, and pressure sensor 56 may be connected to the inlet to estimate compressor inlet pressure. As another example, ambient humidity sensor 57 may be connected to the inlet to estimate the humidity of the air entering the intake manifold. Other sensors may include, for example, an air-fuel ratio sensor. In other examples, one or more compressor inlet conditions (such as humidity, temperature, pressure, etc.) may be inferred based on engine operating conditions. Additionally, when exhaust gas recirculation (EGR) is enabled, the sensors may estimate the temperature, pressure, humidity, and air-fuel ratio of the air-fuel mixture (which includes fresh air, recirculated compressed air, and exhaust residue received at the compressor inlet).

[0016] The wastegate valve 91 can be actuated to open, allowing at least some of the exhaust pressure to be released from upstream of the turbine to downstream of the turbine via the wastegate passage 90. Reducing the exhaust pressure upstream of the turbine can decrease the turbine speed, which in turn helps reduce compressor surge.

[0017] To assist the turbocharger 15, an additional intake compressor (also referred to herein as an electric booster 155) can be integrated into the vehicle propulsion system. The electric booster 155 can be powered via an on-board energy storage device 250, which may include a battery, capacitor, supercapacitor, etc. The electric booster may include a compressor driven by an electric motor. The operating speed of the electric booster may include adjusting the operating speed of the electric motor, which is operated via the on-board energy storage device 250.

[0018] In one example, the electric booster 155 can be actuated in response to the demand for increased wheel torque to rapidly deliver the desired boosted air to the engine during turbocharger acceleration. Thus, the increased torque can be satisfied without causing turbo lag, which could otherwise occur without the assistance of the electric booster. In this example, the electric booster 155 can be actuated to shut down or deactivate in response to the turbocharger accelerating to a threshold speed (e.g., 70,000 rpm). More specifically, the operation control of the electric booster 155 can be implemented based on command signals (e.g., duty cycle or pulse width signals) received from a vehicle controller (e.g., controller 12). For example, the controller can send a signal to the electric booster actuator 155b that can actuate to turn the electric booster on. In another example, the controller can send a signal to the electric booster actuator 155b that can actuate to turn the electric booster off. In one example, the electric booster actuator may include an electric motor that drives air compression.

[0019] An electric booster 155 may be located between a first electric booster conduit 159a and a second electric booster conduit 159b. The first electric booster conduit 159a fluidly connects the intake passage 42 to the electric booster 155 upstream of the electric booster bypass valve 161. The second electric booster conduit 159b fluidly connects the electric booster 155 to the intake passage 42 downstream of the electric booster bypass valve 161. As an example, air may be drawn into the electric booster 155 via the first electric booster conduit 159a upstream of the electric booster bypass valve 161, and compressed air may exit the electric booster 155 and be directed via the second electric booster conduit to the intake passage 42 downstream of the electric booster bypass valve 161. In this way, compressed air can be directed to the engine intake manifold 22.

[0020] When the electric booster 155 is activated to provide boost faster than relying solely on the turbocharger 15, it is understood that when the electric booster 155 is activated, the electric booster bypass valve 161 can be commanded to close. In this way, intake air can flow through the turbocharger 15 and through the electric booster 155. Once the turbocharger reaches its threshold speed, the electric booster 155 can be shut off, and the electric booster bypass valve 161 can be commanded to open.

[0021] Intake manifold 22 is connected to a series of combustion chambers 30 via a series of intake valves (not shown). The combustion chambers are also connected to exhaust manifold 36 via a series of exhaust valves (not shown). In the illustrated embodiment, a single exhaust manifold 36 is shown. However, in other embodiments, the exhaust manifold may include multiple exhaust manifold sections. A configuration with multiple exhaust manifold sections allows effluent from different combustion chambers to be directed to different locations within the engine system.

[0022] In one embodiment, each of the exhaust valve and intake valve may be electronically actuated or electronically controlled. In another embodiment, each of the exhaust valve and intake valve may be cam-actuated or cam-controlled. Whether electronically actuated or cam-actuated, the opening and closing timing of the exhaust valve and intake valve can be adjusted as needed to obtain the desired combustion and emission control performance.

[0023] Combustion chamber 30 can be supplied with one or more fuels, such as gasoline, alcohol-fuel mixtures, diesel, biodiesel, compressed natural gas, etc., via injector 66. Fuel can be supplied to the combustion chamber via direct injection, port injection, throttle body injection, or any combination thereof. Combustion can be initiated in the combustion chamber via spark ignition and / or compression ignition.

[0024] Exhaust gas recirculation (EGR) delivery passage 180 may be coupled to exhaust passage 104 located upstream of turbine 116 to provide high-pressure EGR (HP-EGR) to engine intake manifold located 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 allow a controlled amount of exhaust gas to enter the compressor outlet to achieve desired combustion and emission control performance. EGR valve 152 may be configured as a continuously variable valve or an on / off valve. In a further embodiment, the engine system may include a low-pressure EGR (LP-EGR) flow path, wherein exhaust gas is drawn downstream of turbine 116 and recirculated to engine intake manifold located upstream of compressor 114.

[0025] One or more sensors can be coupled to EGR channel 180 to provide details about the composition and conditions of the EGR. For example, a temperature sensor can be provided to determine the temperature of the EGR, a pressure sensor can be provided to determine the pressure of the EGR, a humidity sensor can be provided to determine the humidity or water content of the EGR, and an air-fuel ratio sensor can be provided to estimate the air-fuel ratio of the EGR. Alternatively, EGR conditions can be inferred by one or more temperature, pressure, humidity, and air-fuel ratio sensors coupled to the compressor inlet.

[0026] Multiple sensors, including an exhaust temperature sensor 128, an exhaust oxygen sensor, and an exhaust flow sensor, can be connected to the main exhaust passage 104. The oxygen sensor can be a linear oxygen sensor or UEGO (universal or wide-range exhaust oxygen), a dual-state oxygen sensor or EGO, HEGO (heated EGO), NOx, HC, or CO sensor.

[0027] like Figure 1 As shown, exhaust gas from one or more exhaust manifold sections can be directed to turbine 116 to drive the turbine. The combined flow from the turbine and exhaust valve passage then flows through exhaust aftertreatment device 170. In one example, emission control device 170 may be an ignition catalytic converter. Typically, exhaust aftertreatment device 170 is configured to catalytically treat the exhaust stream, thereby reducing the amount of one or more substances in the exhaust stream. For example, exhaust aftertreatment device 170 may be configured to capture NO from the exhaust stream when the exhaust stream is lean-burned. x Furthermore, when the exhaust stream is fuel-rich, the captured NO is reduced. x In other examples, the exhaust aftertreatment device 170 may be configured to cause NO to... x NO is reduced disproportionately or selectively with the aid of reducing agents. x In other examples, exhaust aftertreatment device 170 may be configured to oxidize residual hydrocarbons and / or carbon monoxide in the exhaust stream. Different exhaust aftertreatment catalysts with any of this function may be arranged individually or together in the carrier coating or elsewhere in the exhaust aftertreatment stage.

[0028] A particulate filter (PF) 172 can be coupled to an exhaust passage 104 downstream of the exhaust aftertreatment unit 170. The particulate filter 172 can be a gasoline particulate filter or a diesel particulate filter. The substrate of the particulate filter 172 can be made of ceramic, silicon, metal, paper, or a combination thereof. During engine operation, the particulate filter 172 captures exhaust particulate matter (PM), such as ash and soot (e.g., from unburned hydrocarbons), to reduce vehicle emissions. Soot can accumulate on the surface of the particulate filter, creating exhaust back pressure. Exhaust back pressure can negatively impact engine efficiency. To avoid high back pressure, when the PF soot load reaches a threshold load, the engine 10 can opportunistically regenerate the PF at exhaust temperatures above the threshold and under conditions leaner than the stoichiometric air-fuel ratio.

[0029] The pressure in the exhaust system can be assessed by pressure sensor 127. For example, pressure sensor 127 can be a differential pressure sensor connected across PF 172. The PM load accumulated on PF 172 can be estimated based on the pressure drop across PF estimated via pressure sensor 127.

[0030] Hybrid vehicles can utilize extended durations of electric motor torque operation and can exist in non-combustion states during engine operation, such as engine idle stop and deceleration fuel cut-off (DFSO) states. PF 172 regeneration may not be completed during engine combustion states, and it is desirable to perform or continue PF regeneration during engine non-combustion states, including when the vehicle is off. During engine non-combustion states, if the soot load on PF 172 is higher than a first threshold soot load and the PF temperature is higher than a threshold temperature, PF regeneration can be initiated by directing compressed air via PF 172. PF 172 regeneration involves burning the soot load on PF 172 until the soot load decreases below a second threshold, where the first threshold is higher than the second threshold. An electric booster 155 can be operated to allow compressed air to flow from the intake manifold 22 to PF 172. Before operating the electric booster, each of the intake throttle valve 20, EGR valve 152, and exhaust valve 91 can be opened. Ambient air entering through the open throttle valve can be compressed at the electric booster 155, and then the compressed air can flow to PF 172 via each of EGR passage 180 and exhaust valve passage 90. The electric booster 155 can continue to operate until one or more of the following conditions are met: the soot load on PF 172 decreases below a second threshold and the temperature of PF 172 decreases below a threshold temperature.

[0031] Engine system 100 may also include control system 14. Control system 14 is shown receiving information from multiple sensors 16 (various examples of which are described herein) and sending control signals to multiple actuators 18 (various examples of which are described herein). As an example, sensors 16 may include exhaust sensor 126, MAP sensor 124, exhaust temperature sensor 128, exhaust pressure sensor 127, compressor inlet temperature sensor 55, compressor inlet pressure sensor 56, ambient humidity sensor 57, IAT sensor 51, engine coolant temperature sensor, and EGR sensor, etc., located upstream of turbine 116. Other sensors (such as additional pressure sensors, temperature sensors, air-fuel ratio sensors, and component sensors) may be coupled to different locations within engine system 100.

[0032] Actuator 18 may include, for example, an electric booster bypass valve 161, a throttle valve 20, an electric booster actuator 155b, an EGR valve 152, a wastegate valve 91, and a fuel injector 66. Control system 14 may include controller 12. Controller 12 may receive input data from various sensors, process the input data, and trigger various actuators in response to the processed input data based on instructions or codes programmed therein corresponding to one or more programs. In one example, during engine non-combustion conditions, in response to a value above a threshold, the controller may estimate the PM load on the PF via pressure sensor 127 and estimate the exhaust temperature via temperature sensor 128, and in response to each of a PM load above a threshold and an exhaust temperature above a threshold on the PF, controller 12 may signal the electric booster bypass valve 161 to actuate the valve to a closed position and signal the booster actuator 155b to actuate the electric booster 155, thereby directing compressed air through the PF for PF regeneration.

[0033] In some examples, vehicle 102 may be a hybrid vehicle having multiple torque sources available for one or more wheels 157. In other examples, vehicle 102 may be a conventional vehicle with only an engine, or an electric vehicle with only an electric motor. In the example shown, vehicle 102 includes an engine 10 and an electric motor 52. The electric motor 52 may be a motor or a motor / generator (M / G). When one or more clutches 156 are engaged, the crankshaft of engine 10 and electric motor 52 are connected to wheels 157 via transmission 54. In the depicted example, a first clutch 156 is disposed between the crankshaft and electric motor 52, and a second clutch 156 is disposed between electric motor 52 and transmission 54. Controller 12 may send signals to the actuators of each clutch 156 to engage or disengage the clutches to connect or disconnect the crankshaft from electric motor 52 and its connected components, and / or connect or disconnect electric motor 52 from transmission 54 and its connected components. Transmission 54 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain may be configured in various ways, including parallel, series, or series-parallel hybrid vehicles.

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

[0035] In this way, Figure 1The components in the document implement a system for a vehicle (including autonomous vehicles and / or hybrid vehicles), the system comprising: an engine including one or more cylinders, an intake manifold, and an exhaust manifold; an intake passage including a turbine-driven compressor, a boost air cooler (CAC) downstream of the compressor, and an intake throttle valve downstream of the CAC; a duct connecting to the intake passage downstream of the compressor and upstream of the CAC, the duct including a motor-driven electric compressor; an electric compressor bypass valve connected at the junction of the intake passage and the duct; an exhaust passage including a turbine, a particulate filter (PF), a differential pressure sensor connected to both ends of the PF, and a temperature sensor upstream of the PF; an exhaust gas recirculation (EGR) passage connecting the exhaust manifold to the intake manifold downstream of the compressor, the EGR passage including an EGR valve; and a wastegate passage connecting to an exhaust passage from upstream of the turbine to downstream of the turbine, the wastegate passage including a wastegate valve. The system also includes a controller having computer-readable instructions stored in a non-transient memory to control the following operations when the engine is not burning fuel and air: estimating the particulate matter (PM) load on the PF via a differential pressure sensor; estimating the exhaust temperature via a temperature sensor; and, in response to each of the PM load being higher than a threshold load and the exhaust temperature being higher than a threshold temperature, opening each of the throttle valve, the EGR valve, and the wastegate valve, and operating the electric booster for a duration to direct compressed air to the PF for regeneration.

[0036] Figure 2 An exemplary method 200 for regenerating an exhaust particulate filter (PF) during engine non-combustion conditions is shown. Instructions for performing method 200 and the remaining methods included herein can be generated by a controller based on instructions stored in the controller's memory and in conjunction with those from sensors in the engine system (such as those referenced above). Figure 1 The controller uses the signals received by the sensor to perform the operation. The controller can adjust the engine operation using the engine actuator of the engine system according to the method described below.

[0037] At point 202, the current engine and vehicle operating status can be estimated, measured, and / or inferred. Operating status can include: one or more vehicle conditions, such as vehicle speed, vehicle position, etc.; various engine conditions, such as engine status, engine load, engine speed, A / F ratio, engine temperature, exhaust temperature, exhaust pressure; various evaporative emission system conditions; and various environmental conditions, such as ambient temperature, humidity, air pressure, etc. The particulate matter load (also referred to here as soot) on the PF can be estimated based on the exhaust pressure. The exhaust pressure can be obtained via an exhaust differential pressure sensor (such as...) connected across the PF. Figure 1The pressure sensor 127 in the controller is used to estimate the PF soot load. The PF soot load can be proportional to the exhaust pressure. In one example, the controller can use a lookup table to determine the PF load based on the estimated exhaust pressure, where the input is the exhaust pressure and the output is the PF soot load.

[0038] At 204, the procedure includes determining whether the soot load on the PF is higher than a first threshold load (threshold_1). Threshold_1 can be calibrated based on exhaust back pressure, and threshold_1 soot load can correspond to a soot load level that, if higher than this level, may adversely affect exhaust gas discharge from the cylinders, thus adversely affecting engine efficiency. If the PF load is determined to be lower than threshold_1, it can be inferred that PF regeneration is probably not desired at this time. At 206, current engine operation can continue without initiating PF regeneration. In one example, the electric booster (such as...) can be operated as needed. Figure 1 An electric booster 155 is used to provide boost assistance during periods of increased torque demand. The electric booster may be coupled to a duct connected in parallel with the intake passage, which is downstream of the intake compressor and upstream of the boost air cooler. This is achieved by operating a turbocharger (such as...) Figure 1 If the boost pressure provided by the intake compressor 114 and exhaust turbine 116 is lower than the desired boost pressure, energy can be supplied from an on-board energy storage device (such as...). Figure 1 The energy storage device 250 in the device operates the electric booster to provide the desired boost. The operating speed and duration of the electric booster can be adjusted based on the turbocharger speed and the torque demand estimated via a pedal position sensor. In one example, the operating speed and duration of the electric booster can increase as the torque demand increases and the turbocharger speed decreases. In another example, the operating speed and duration of the electric booster can decrease as the torque demand decreases and the turbocharger speed increases.

[0039] If the soot load on the PF is determined to be above threshold _1, then at 208, the procedure includes determining whether the conditions for PF regeneration are met. The conditions for PF regeneration may include an engine load above the threshold such that an exhaust temperature above the threshold is available for PF regeneration. PF regeneration can be performed at an exhaust temperature above the threshold. The threshold exhaust temperature can be calibrated based on the temperature required to oxidize the accumulated particulate matter in the presence of oxygen. When the engine load is above the threshold load, the engine's thermal output is sufficient to sustain PF regeneration and can burn the entire volume of PM accumulated on the PF. PF regeneration can be performed during deceleration fuel cut-off (DFSO) conditions, where there is excess oxygen in the exhaust gas stream, which promotes PF regeneration. Furthermore, PF regeneration can be performed in a leaner process than stoichiometric engine operation, allowing the accumulated soot to be oxidized.

[0040] If the conditions for PF regeneration are determined to be met, the PF can be regenerated at 210 by oxidizing the accumulated soot. In one example, during PF regeneration, fuel from the fuel tank can be injected into the exhaust passage via a fuel injector to further accelerate soot combustion at the PF.

[0041] If it is determined that the conditions for PF regeneration are not met, at 212, the procedure includes determining whether the engine is in a non-combustion state. An engine non-combustion state may include an engine idle stop state, a deceleration fuel cut-off (DFSO) state, and an engine shutdown event. For example, engine combustion may be interrupted when one or more idle stop states are met. As an example, an engine idle stop state may include an engine idling time longer than a threshold duration (such as at a traffic interruption), a state of charge (SOC) of the battery connected to the motor greater than a threshold (such as at least 30% charge), or the air conditioner not requesting a restart of the engine (which would be requested if air conditioning is desired). Furthermore, if the vehicle speed is below a threshold (e.g., 3 mph), engine idle stop may be requested even if the vehicle is not stationary. Additionally, prior to engine idle stop, an emission control device connected to the engine's exhaust manifold may be analyzed to determine that no request for engine restart has been made.

[0042] As another example, during DFSO, fuel injection into the engine cylinders can be stopped, while the cylinder valves continue to operate and pump air through the cylinders, and the engine continues to rotate. In one example, DFSO can respond to the release of the accelerator pedal (i.e., where the operator has released the accelerator pedal and requested a reduction in torque), such as when the vehicle may coast.

[0043] As another example, when the vehicle uses only the motor from a hybrid electric vehicle (HEV) (such as...) Figure 1 When propelled by the motor torque of the electric motor 52), the engine may be without combustion and remain stationary. The vehicle can be propelled via motor torque during periods below a threshold engine load and above a threshold SOC of the motor battery. The threshold engine load can be calibrated based on vehicle operating conditions, including vehicle speed and battery SOC. The threshold SOC may correspond to the minimum motor power required to propel the vehicle. As another example, when the vehicle is stationary and not propelled by engine torque and / or motor torque, the engine may be without combustion and remain off.

[0044] If it is determined that no engine non-combustion conditions are met, it can be inferred that the engine is burning air and fuel. At 214, PF regeneration can be delayed until the conditions for PF regeneration are met. In one example, the controller can actively adjust engine operating parameters, such as by increasing the air-fuel ratio and delaying the spark timing from the maximum braking torque (MBT) to increase exhaust temperature.

[0045] If it is determined that the engine is in a non-combustion state, then at 216, the procedure includes via an exhaust temperature sensor (such as...) connected upstream of the PF to the exhaust passage. Figure 1 The temperature sensor 128 in the middle determines whether the estimated exhaust temperature or PF temperature is higher than the threshold exhaust temperature. As previously mentioned, the threshold exhaust temperature can be calibrated based on the temperature required for the combustion of accumulated particulate matter. Even after combustion has ceased, residual waste heat may remain, and this heat may be used opportunistically to regenerate the PF. In one example, the exhaust catalyst upstream of the PF (such as...) Figure 1 The exhaust aftertreatment device 170 can retain heat for an extended period of time, and this heat can be directed to the PF to initiate PF regeneration. In one example, a heater can be connected to the PF, and during exhaust temperatures below a threshold, the heater can be activated to increase the temperature of the PF to the threshold temperature.

[0046] If the exhaust temperature is determined to be below a threshold exhaust temperature, the program can proceed to step 214 and PF regeneration can be delayed until the conditions for PF regeneration can be met, such as after a subsequent engine combustion state. If the exhaust temperature is determined to be above a threshold temperature, then at 218, the controller can direct the input to the intake throttle (such as...) Figure 1 The controller sends a signal to the actuator of the intake throttle valve 20 to actuate the throttle valve to the fully open position. The controller can also send a signal to the exhaust gas recirculation valve (such as...) connected to the EGR passage. Figure 1 The controller sends a signal to the EGR valve 152 in the system to fully open the EGR valve. Additionally, the controller can send a signal to the exhaust gas valve (such as...) Figure 1 The exhaust valve 91 in the middle sends a signal to actuate the exhaust valve to the fully open position.

[0047] At 220, an electric air compressor can be operated to allow pressurized air to flow through the PF to initiate PF regeneration. The controller can send commands to the electric air compressor actuator (such as...) Figure 1The actuator 155b sends a signal to actuate the electric air compressor using energy from an energy storage device coupled to the electric booster. As ambient air enters the intake manifold via a fully open throttle valve and flows through the electric air compressor, the air is pressurized (compressed), and then the compressed air can flow from the intake manifold to the exhaust manifold via each of the EGR passage and the wastegate passage. Because the engine is not rotating, the intake and exhaust valves of one or more cylinders may not be in the open position to allow compressed air to flow from the intake manifold to the exhaust manifold. However, an open EGR valve provides an air passage via the EGR passage. When compressed air enters the exhaust manifold, the wastegate passage provides a lower resistance path for the compressed air relative to the turbine and promotes airflow towards the PF. The air flowing to the PF via the catalyst upstream of the PF provides the power to transfer heat from the catalyst to the PF, so the heated air flowing through the PF can initiate the oxidation of soot accumulated on the PF. Due to the compressed air, a higher concentration of oxygen is present in the PF. Under the elevated temperature and in the presence of oxygen, the soot accumulated on the PF can be oxidized.

[0048] At point 222, changes in the PF load can be monitored during the regeneration process. As regeneration continues, the soot load on the PF can decrease continuously, and there may be a corresponding change in the exhaust pressure estimated via a differential pressure sensor connected across the PF.

[0049] At 224, the procedure includes determining whether the PF load has decreased below a second threshold (threshold_2). Threshold_2 can be calibrated based on exhaust back pressure, and the threshold_2 soot load can correspond to a soot load level at which the corresponding exhaust back pressure does not adversely affect engine operation. Furthermore, when the soot load is below threshold_2, the PF's filtering capacity may be adversely affected. Therefore, once the PF load reaches threshold_2, it may not be desirable to remove any further soot from the PF. Therefore, if it is determined that the PF load has reached threshold_2, at 232, the controller can send a signal to the electric booster actuator to deactivate the electric booster. Once the electric booster is deactivated, the airflow through the PF can be paused, thereby reducing the oxygen available at the PF (as required to maintain the regeneration process). Therefore, PF regeneration stops, and the engine can return to a non-combustion state. The operating duration of the electric booster can be proportional to the difference between the PM load and threshold_1. The operating duration of the electric booster can increase as the difference between the PM load and the threshold_1 increases, and similarly, the operating duration of the electric booster can decrease as the difference between the PM load and the threshold_1 decreases.

[0050] Before operating the electric booster, the intake throttle, EGR valve, and exhaust valve can be adjusted to their respective positions. At the end of the regeneration process, the remaining PF load can be estimated based on the pressure drop across the PF as estimated via a differential pressure sensor.

[0051] If the PF load is determined to be above threshold_2, then at 226, the procedure includes determining whether the exhaust temperature has decreased to below the threshold exhaust temperature. Since combustion is not occurring, the PF may not have any effective heat supply. If the exhaust temperature decreases below the threshold temperature, the oxidation reaction of accumulated soot particles may no longer occur. Therefore, if it is determined that even if the soot load on the PF is above threshold_2, the exhaust temperature is below the threshold temperature, the procedure can proceed to step 230, where the electric booster can be deactivated to pause compressed air flow through the PF, and the PF load estimate can be updated.

[0052] If it is determined that the exhaust temperature continues to remain above the threshold temperature, at 230, the controller can determine whether engine combustion has been resumed. Combustion can be resumed in response to one or more of the following: an increase in torque demand (depressing the accelerator pedal), a decrease in the state of charge (SOC) of the battery connected to the motor below the threshold SOC, and vehicle ignition. At the start of combustion, the electric booster speed operation can be adjusted based on torque demand. Furthermore, the positions of each of the intake throttle, EGR valve, and exhaust valve can be adjusted based on engine operating parameters such as engine load, engine speed, and engine temperature. Therefore, if it is determined that engine combustion has been resumed, the procedure can proceed to 232 to deactivate the electric booster even if PF regeneration has not yet been completed. In one example, based on engine boost demand, the electric booster can continue to operate regardless of PF soot load.

[0053] During the subsequent engine start-up (combustion) period, one or more engine operating parameters, such as air-fuel ratio and spark timing, can be adjusted based on the state of PF regeneration. In one example, regeneration may begin and terminate before the particulate filter regeneration is complete (e.g., partially completed). In another example, depending on the temperature of the three-way catalytic converter during engine shutdown regeneration, more or less excess oxygen may be stored at the three-way catalytic converter upstream of the PF.

[0054] For example, if regeneration is attempted but only partially completed, the oxygen in the three-way catalytic converter may be less than in a case of more complete regeneration. Therefore, the air-fuel ratio can be adjusted to a richer (or leaner) stoichiometry to reduce excess oxygen in the catalytic converter during engine start-up. In another example, if regeneration is not completed during the engine's non-combustion phase, the engine can be started in this manner to continue regeneration. For instance, in vehicles with hybrid electric drive systems, the engine may need to be started during vehicle acceleration, and the particulate filter regeneration may not have been completed during engine shutdown. In this case, the air-fuel ratio can be adjusted to a lean stoichiometry, and the spark timing can be delayed to continue supplying oxygen to the particulate filter for regeneration. Therefore, based on the regeneration status during engine shutdown, the engine can be restarted in such a way that regeneration continues or the impact of regeneration on components such as the three-way catalytic converter is reduced.

[0055] If it is determined that the PF load is below threshold 2, the exhaust temperature is above the threshold temperature, and engine combustion has not yet recovered, then at 228, the electric booster operation can continue to supply compressed air to the PF for regeneration.

[0056] In this way, during engine shutdown, in response to a carbon soot load on the particulate filter (PF) coupled to the engine's exhaust passage exceeding a first threshold load, the PF can be selectively regenerated by directing compressed air from the engine's intake passage to the PF, the compressed air being directed to the PF by operating an electric booster coupled to the intake passage.

[0057] Figure 3 An exemplary operating sequence 300 is shown, which illustrates an electric booster (such as...) Figure 1 Exemplary operation of the electric booster 155, which is coupled to the engine intake manifold for use with a particulate filter (such as...) Figure 1 The PF 172 is regenerated. The horizontal axis (x-axis) represents time, and the vertical markers t1-t3 represent important moments in the PF regeneration.

[0058] The first curve (line 302) shows the change in engine speed over time. The second curve (line 304) shows the amount of soot accumulated on the PF, based on a differential pressure sensor (such as...) connected across the PF. Figure 1The pressure drop across the PF is estimated by the pressure sensor 127 in the middle. Dashed line 305 represents the upper threshold load, above which PF regeneration is required, and dashed line 306 represents the lower threshold load, above which regeneration can be interrupted. The upper threshold 305 can be calibrated based on the exhaust back pressure that may negatively affect engine efficiency. The lower threshold 306 can be calibrated based on the exhaust back pressure that may no longer adversely affect engine performance. The third curve (line 307) shows the change in exhaust temperature, based on the exhaust temperature from an exhaust temperature sensor (such as...) connected upstream of the PF to the exhaust passage. Figure 1 The temperature is estimated based on the input of the temperature sensor 128. Dashed line 308 represents the threshold exhaust temperature; if this temperature is higher, the soot deposited on the PF can be oxidized in the presence of oxygen. The threshold exhaust temperature 308 can be calibrated based on the temperature required to burn the accumulated particulate matter. The fourth curve (line 309) shows the operation of the electric booster. The fifth curve (line 310) shows the opening of the intake throttle. The fifth curve (line 312) shows the opening of the exhaust gas recirculation (EGR) valve connected to the EGR passage. The sixth curve (line 314) shows the location of the exhaust valve housed in the exhaust valve passage, which is connected in parallel with the turbine located in the exhaust system.

[0059] Before time t1, the engine is operated for vehicle propulsion, and the electric booster is operated to provide the desired boost pressure. The intake throttle opening is adjusted based on torque demand. During this period, EGR is not desired based on engine dilution requirements, and the EGR valve remains closed. Based on torque demand, it is desired to guide the entire exhaust volume via the exhaust turbine; therefore, the exhaust gas valve remains closed. The PF load continues to increase and reaches the upper threshold of 305, and PF regeneration is expected. However, at time t1, the engine shuts off, and the engine speed decreases to zero. During engine shutdown, no active air (oxygen) is supplied through the PF, thus reducing the likelihood of PF regeneration.

[0060] At time t2, based on the exhaust temperature above the threshold of 308, it is inferred that PF regeneration can be initiated in the presence of oxygen. Once the engine has completely stopped rotating, the controller sends a signal to the intake throttle valve to increase its opening to the fully open position. The controller sends a signal to the actuator connected to the EGR valve to fully open the EGR valve, and a signal to the actuator connected to the wastegate valve to fully open the wastegate valve. The controller then sends a signal to the actuator connected to the electric booster to initiate the operation of the electric booster. The electric booster used to supply compressed air to the PF operates at a lower speed than the electric booster used to provide the required boost pressure (such as the operating speed before time t1). Between times t2 and t3, the air entering via the fully open throttle valve is compressed at the electric booster, and the compressed air is directed to the PF via the open EGR passage and the open wastegate passage. The compressed air provides the power to allow the heat energy from the exhaust passage to reach the PF. In the presence of oxygen from compressed air and an exhaust temperature above the threshold, the soot accumulated on the PF is oxidized and the PF load is steadily reduced.

[0061] At time t3, in response to the PF load decreasing below the second threshold 306, it is inferred that PF regeneration is complete and further soot oxidation is no longer needed. Therefore, the controller sends a signal to the electric booster actuator to suspend the operation of the electric booster. When the compressed air flow via the PF stops, oxygen availability decreases and PF regeneration is suspended. Moreover, after time t3, the exhaust temperature decreases below the threshold temperature 308, causing soot oxidation to cease. Upon completion of PF regeneration, the intake throttle is actuated to the position it was in before initiating PF regeneration (e.g., before time t2), the EGR valve closes, and the exhaust gas valve closes. The engine remains in a non-combustion state until further engine torque is required.

[0062] In this way, by opportunistically regenerating the exhaust particulate filter (PF) during engine non-combustion periods without rotating the engine, emissions quality can be improved and the operator's preference for operating the vehicle via electric motor torque can be maintained. By allowing compressed air to flow through the exhaust passages during PF regeneration, thermal energy from the exhaust catalyst located upstream of the PF can be directed to the PF to promote regeneration. The technical advantage of reusing the electric booster for PF regeneration is that it may eliminate the need for additional engine components, thus removing the requirement for such parts. Overall, by maintaining a clean PF, emissions quality and engine performance can be improved.

[0063] An exemplary engine method includes: during a non-combustion state of an engine coupled to a vehicle, in response to a soot load on a particulate filter (PF) coupled to the engine's exhaust passage exceeding a first threshold and a PF temperature exceeding a threshold temperature required for soot oxidation in the presence of oxygen, activating an electric booster in the engine's intake system to direct compressed air to the PF for PF regeneration.

[0064] An exemplary method includes: during a non-combustion state of an engine coupled to a vehicle, in response to a soot load on a particulate filter (PF) coupled to the engine's exhaust passage exceeding a first threshold and a PF temperature exceeding a threshold temperature required for soot oxidation in the presence of oxygen, activating an electric booster in the engine's intake system to direct compressed air to the PF for PF regeneration. In any of the foregoing examples, additionally or optionally, the non-combustion state of the engine driving the vehicle includes one of a deceleration cutoff of fuel delivered to the engine, an engine idle-stop state, a vehicle shutdown state, and a vehicle propulsion period utilizing only electric motor torque. In any or all of the foregoing examples, additionally or optionally, the soot load on the PF is estimated based on input from a differential pressure sensor coupled across the PF, and wherein the PF temperature is estimated based on input from a temperature sensor coupled upstream of the PF. In any or all of the foregoing examples, the electric air compressor is coupled to a duct in parallel with the engine's intake passage, the duct being coupled downstream of the intake compressor and upstream of the boost air cooler to the intake passage. The method further includes: closing an electric booster bypass valve coupled downstream of the intake compressor to the intake passage to introduce ambient air into the duct. In any or all of the foregoing examples, additionally or optionally, the engine includes an exhaust gas recirculation (EGR) passage that connects the exhaust passage downstream of the electric booster to the intake passage, and wherein directing the compressed air to the PF further includes: opening an exhaust gas recirculation (EGR) valve coupled to the EGR passage to allow compressed air exiting the electric booster to flow to the PF via the EGR passage. In any or all of the foregoing examples, the method further includes, additionally or optionally, actuating an intake throttle valve connected downstream of the boost air cooler to the intake passage to a fully open position while opening the EGR valve, and actuating an exhaust valve located in an exhaust valve passage to introduce compressed air from the electric air compressor into the exhaust system, the exhaust valve passage being connected in parallel with a turbine located in the exhaust system. In any or all of the foregoing examples, the method further includes, additionally or optionally, deactivating the electric booster in response to a decrease in soot load on the PF to below a second threshold soot load, wherein the second threshold is lower than the first threshold. In any or all of the foregoing examples, the method further includes, additionally or optionally, deactivating the electric booster in response to a decrease in PF temperature to below the threshold temperature. In any or all of the foregoing examples, the method further includes, additionally or optionally, activating a heater connected to the PF during the non-combustion state of the engine in response to a soot load on the PF above the first threshold and an exhaust temperature below the threshold, before activating the electric booster.

[0065] Another exemplary method includes: during engine shutdown, and in response to a soot load on a particulate filter (PF) coupled to the engine's exhaust passage exceeding a first threshold load, selectively regenerating the PF by directing compressed air from the engine's intake passage to the PF, the compressed air being supplied by operating an electric booster coupled to the intake passage and opening a throttle valve coupled to the intake passage. In any of the foregoing examples, additionally or optionally, selective PF regeneration is in response to the temperature of the PF exceeding a threshold temperature required for soot oxidation during the directing of compressed air through the PF. In any or all of the foregoing examples, additionally or optionally, selective PF regeneration is in response to the temperature of a catalyst coupled upstream of the PF to the exhaust passage exceeding the threshold temperature, and wherein the compressed air is directed to the PF via the catalyst, the compressed air transferring heat energy from the catalyst to the PF. In any or all of the foregoing examples, the method further includes, additionally or optionally, opening each of the throttle valve, exhaust gas recirculation (EGR) valve, and wastegate valve prior to operation of the electric booster, the EGR valve being coupled to an EGR passage connecting the intake passage to the exhaust passage, and the wastegate valve being coupled to a wastegate passage to bypass a turbine coupled to the exhaust passage. In any or all of the foregoing examples, additionally or optionally, directing compressed air includes directing ambient air compressed at the electric booster to the PF via each of the EGR passage and the wastegate passage. In any or all of the foregoing examples, additionally or optionally, operation of the electric booster continues until one or more of the following conditions are met: the soot load on the PF decreases below a second threshold and the temperature of the PF decreases below the threshold temperature. In any or all of the foregoing examples, additionally or optionally, regenerating the PF includes burning the soot load on the PF until the soot load decreases below the second threshold, the first threshold being higher than the second threshold. In any or all of the foregoing examples, additionally or optionally, the engine shutdown state includes: a state in which fuel injection and sparking of one or more engine cylinders are deactivated to suspend the combustion of fuel and air.

[0066] In yet another example, a system includes: a controller having computer-readable instructions stored in a non-transient memory to control the following operations when the engine coupled to a vehicle is not burning fuel and air: estimating the particulate matter (PM) load on the PF contained in the exhaust passage of the engine via a differential pressure sensor coupled across the particulate filter (PF); estimating the exhaust temperature via a temperature sensor coupled upstream of the PF to the exhaust passage; and, in response to each of the conditions that the PM load is higher than a threshold load and the exhaust temperature is higher than a threshold temperature, opening each of an intake throttle valve, an exhaust gas recirculation (EGR) valve, and a waste gas valve, the EGR valve being housed in an EGR passage that connects the exhaust manifold to the intake manifold, the waste gas valve being housed in a waste gas valve passage that connects to an exhaust passage from upstream to downstream of the exhaust turbine, and operating a motor-driven electric compressor housed in a duct coupled to the intake passage for a duration to direct compressed air to the PF for regeneration. In any or all of the foregoing examples, additionally or optionally, the duration of operation of the electric booster is proportional to the difference between the PM load and the threshold load, and the duration increases with the difference. In any or all of the foregoing examples, additionally or optionally, the vehicle is an autonomous vehicle and / or a hybrid vehicle, the PF is a heated PF, and during operation of the electric booster, the controller further includes instructions for activating a heater coupled to the PF.

[0067] Note that the exemplary control and estimation programs included herein can be used in various engine and / or vehicle system configurations. The control methods and programs disclosed herein can be stored as executable instructions in non-transient memory and can be executed by a control system including a controller in conjunction with various sensors, actuators, and other engine hardware. The specific programs described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threaded processing strategies, etc. Therefore, the various actions, operations, and / or functions shown can be executed in the order shown, in parallel, or may be omitted under certain conditions. Similarly, the processing order is not necessarily necessary to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the shown actions, operations, and / or functions can be repeatedly executed according to the specific strategy used. Furthermore, the described actions, operations, and / or functions can be graphically represented as code to be programmed into the non-transient memory of a computer-readable storage medium in the engine control system, wherein the described actions are implemented by executing instructions in conjunction with an electronic controller in a system including various engine hardware components.

[0068] It should be understood that the configurations and procedures disclosed herein are exemplary in nature, and these specific embodiments should not be considered limiting, as many variations are possible. For example, the above-described techniques can be applied to V-6, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of this disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations disclosed herein, as well as other features, functions, and / or characteristics.

[0069] The following claims specifically point to certain combinations and sub-combinations that are considered novel and non-obvious. These claims may refer to an element “a” or a “first” element or its equivalent. Such claims should be understood to include combinations of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or attributes may be claimed by amending these claims or by setting new claims in this application or related applications. Such claims, whether broader, narrower, identical, or different in scope from the original claims, are also considered to be included within the subject matter of this disclosure.

[0070] According to the present invention, a method includes: during a non-combustion state of an engine coupled to a vehicle, in response to a soot load on a particulate filter (PF) coupled to the exhaust passage of the engine exceeding a first threshold and a PF temperature exceeding a threshold temperature required for soot oxidation in the presence of oxygen, activating an electric booster in the intake system of the engine to direct compressed air to the PF for PF regeneration.

[0071] According to one embodiment, the non-combustion state of the engine driving the vehicle includes one of the following: deceleration cutoff of fuel delivered to the engine, engine idle-stop state, vehicle shutdown state, and vehicle propulsion period utilizing only electric motor torque.

[0072] According to one embodiment, the soot load on the PF is estimated based on input from a differential pressure sensor connected to both ends of the PF, and the temperature of the PF is estimated based on input from a temperature sensor connected to the exhaust passage upstream of the PF.

[0073] According to one embodiment, the electric air compressor is connected to a duct in parallel with the intake passage of the engine, the duct being connected to the intake passage downstream of the intake compressor and upstream of a booster air cooler, the method further comprising: closing an electric booster bypass valve connected to the intake passage downstream of the intake compressor to introduce ambient air into the duct.

[0074] According to one embodiment, the engine includes an exhaust gas recirculation passage that connects the exhaust gas passage downstream of the electric booster to the intake passage, and wherein directing the compressed air to the PF further includes: opening an exhaust gas recirculation (EGR) valve connected to the exhaust gas recirculation passage to allow compressed air exiting the electric booster to flow to the PF via the EGR passage.

[0075] According to one embodiment, the invention is further characterized in that, while opening the EGR valve, the intake throttle valve connected downstream of the boost air cooler to the intake passage is actuated to the fully open position, and the exhaust valve located in the exhaust valve passage is actuated to introduce compressed air from the electric air compressor into the exhaust system, the exhaust valve passage being connected in parallel with the turbine located in the exhaust system.

[0076] According to one embodiment, the invention is further characterized in that, in response to the soot load on the PF decreasing to below a second threshold soot load, the electric booster is deactivated, wherein the second threshold is lower than the first threshold.

[0077] According to one embodiment, the invention is further characterized in that the electric booster is deactivated in response to the PF temperature dropping below the threshold temperature.

[0078] According to one embodiment, the invention is further characterized in that, during the non-combustion state of the engine, in response to a soot load on the PF above a first threshold and an exhaust temperature below a first threshold, the heater connected to the PF is activated before the electric booster is activated.

[0079] According to the present invention, a method includes: during an engine-off state, and in response to a soot load on a particulate filter (PF) coupled to an exhaust passage of the engine exceeding a first threshold load, selectively regenerating the PF by directing compressed air from an intake passage of the engine to the PF, the compressed air being supplied by operating an electric booster coupled to the intake passage and opening a throttle valve coupled to the intake passage.

[0080] According to one embodiment, selective regeneration of the PF is in response to the temperature of the PF being higher than the threshold temperature required for soot oxidation during the guiding of compressed air through the PF.

[0081] According to one embodiment, selective regeneration of the PF is in response to a temperature of a catalyst connected upstream of the PF to the exhaust passage being higher than the threshold temperature, wherein the compressed air is directed to the PF via the catalyst, and the compressed air transfers heat energy from the catalyst to the PF.

[0082] According to one embodiment, the invention is further characterized in that, prior to operation of the electric booster, each of the throttle valve, exhaust gas recirculation (EGR) valve, and wastegate valve is opened, the EGR valve being connected to an EGR passage that connects the intake passage to the exhaust passage, and the wastegate valve being connected to a wastegate passage to bypass the turbine connected to the exhaust passage.

[0083] According to one embodiment, guiding compressed air includes guiding ambient air compressed at the electric booster to the PF via each of the EGR passage and the exhaust valve passage.

[0084] According to one embodiment, the operation of the electric booster continues until one or more of the following conditions are met: the soot load on the PF decreases below a second threshold and the temperature of the PF decreases below the threshold temperature.

[0085] According to one embodiment, regenerating the PF includes: burning the soot load on the PF until the soot load is reduced to below a second threshold, wherein the first threshold is higher than the second threshold.

[0086] According to one embodiment, the engine shutdown state includes: a state in which fuel injection and sparking of one or more engine cylinders are deactivated to suspend the combustion of fuel and air.

[0087] According to the present invention, a system is provided comprising: a controller having computer-readable instructions stored in a non-transient memory to control the following operations when an engine coupled to a vehicle is not burning fuel and air: estimating the particulate matter (PM) load on the PF contained in the exhaust passage of the engine via a differential pressure sensor coupled across the particulate filter (PF); estimating the exhaust temperature via a temperature sensor coupled upstream of the PF to the exhaust passage; opening each of an intake throttle valve, an exhaust gas recirculation (EGR) valve, and a waste gas valve in response to each of the conditions that the PM load is higher than a threshold load and the exhaust temperature is higher than a threshold temperature, the EGR valve being housed in an EGR passage connecting the exhaust manifold to the intake manifold, the waste gas valve being housed in a waste gas valve passage connected to an exhaust passage from upstream to downstream of the exhaust turbine, and operating a motor-driven electric compressor housed in a duct coupled to the intake passage for a duration to direct compressed air to the PF for regeneration.

[0088] According to one embodiment, the duration of operation of the electric booster is proportional to the difference between the PM load and the threshold load, and the duration increases with the difference.

[0089] According to one embodiment, the vehicle is an autonomous vehicle and / or a hybrid vehicle, the power supply (PF) is a heated PF, and during operation of the electric booster, the controller further includes instructions for activating the heater coupled to the PF.

Claims

1. A method for an engine, comprising: During the non-combustion state of the engine connected to the vehicle, In response to a soot load exceeding a first threshold and a PF temperature exceeding the threshold temperature required for soot oxidation in the presence of oxygen, on the particulate filter (PF) coupled to the exhaust passage of the engine, The electric booster in the engine's intake system is activated to direct compressed air to the power filter (PF) for PF regeneration. The electric booster is connected to a duct in parallel with the engine's intake passage, the duct being connected to the intake passage downstream of the intake compressor and upstream of the boost air cooler.

2. The method of claim 1, wherein the non-combustion state of the engine driving the vehicle includes one of a deceleration cutoff of fuel delivered to the engine, an engine idle-stop state, a vehicle shutdown state, and a vehicle propulsion period utilizing only the torque of the electric motor.

3. The method of claim 1, wherein the soot load on the PF is estimated based on input from a differential pressure sensor connected to both ends of the PF, and wherein the temperature of the PF is estimated based on input from a temperature sensor connected to the exhaust passage upstream of the PF.

4. The method of claim 1, further comprising: Close the electric booster bypass valve connected downstream of the intake compressor to the intake passage to introduce ambient air into the duct.

5. The method of claim 1, wherein the engine includes an exhaust gas recirculation passage that connects the exhaust passage downstream of the electric booster to the intake passage, and wherein directing the compressed air to the PF further includes: Open the exhaust gas recirculation (EGR) valve connected to the exhaust gas recirculation passage to allow compressed air leaving the electric booster to flow to the PF via the EGR passage.

6. The method of claim 5, further comprising: While the EGR valve is opened, the intake throttle valve, which is connected downstream of the boost air cooler to the intake passage, is actuated to the fully open position, and the exhaust valve in the exhaust passage is actuated to introduce compressed air from the electric booster into the exhaust system, the exhaust passage being connected in parallel with the turbine in the exhaust system.

7. The method of claim 1, further comprising: In response to one or more of the following conditions: the soot load on the PF decreases to below a second threshold soot load and the PF temperature decreases to below the threshold temperature, the electric booster is deactivated, wherein the second threshold is lower than the first threshold.

8. The method of claim 1, further comprising: During the non-combustion state of the engine, in response to a soot load on the PF above a first threshold and an exhaust temperature below a first threshold, the heater connected to the PF is activated before the electric booster is activated.

9. A system for an engine, comprising: The controller has computer-readable instructions stored in non-transient memory to control the following operations when the engine coupled to the vehicle is not burning fuel and air: In response to the soot load on the particulate filter (PF) coupled to the exhaust passage of the engine exceeding a first threshold load, The power filter (PF) is selectively regenerated by directing compressed air from the engine's intake manifold to the PF, the compressed air being supplied by operating an electric booster connected to the intake manifold and opening a throttle valve connected to the intake manifold. The electric booster is connected to a duct in parallel with the intake passage of the engine, the duct being connected to the intake passage downstream of the intake compressor and upstream of the boost air cooler.

10. The system of claim 9, wherein the selective regeneration of the PF is in response to the temperature of the PF being higher than the threshold temperature required for soot oxidation during the guiding of compressed air through the PF.

11. The system of claim 10, wherein the selective regeneration of the PF is in response to a temperature of a catalyst coupled upstream of the PF to the exhaust passage being higher than the threshold temperature, and wherein the compressed air is directed to the PF via the catalyst, the compressed air transferring thermal energy from the catalyst to the PF.

12. The system of claim 9, wherein the controller includes further instructions for: prior to operation of the electric booster, opening each of the throttle valve, the exhaust gas recirculation (EGR) valve, and the wastegate valve, the EGR valve being coupled to an EGR passage connecting the intake passage to the exhaust passage, and the wastegate valve being coupled to a wastegate passage to bypass a turbine coupled to the exhaust passage.

13. The system of claim 12, wherein guiding the compressed air comprises: The ambient air compressed at the electric booster is directed to the PF via each of the EGR passage and the exhaust valve passage.

14. The system of claim 10, wherein operation of the electric booster continues until one or more of the following conditions are met: the soot load on the PF decreases below a second threshold and the temperature of the PF decreases below the threshold temperature.

15. The system of claim 14, wherein the regeneration of the PF comprises: The soot load on the PF is burned until the soot load is reduced to below the second threshold, where the first threshold is higher than the second threshold.

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