Method and system for managing exhaust gas composition

Abstract

Combustion event data is received from at least one combustion event sensor assigned to a plurality of cylinders. Each cylinder comprises a combustion chamber, an intake valve, and an exhaust valve. Opening the intake valve allows air to flow from an intake manifold into the combustion chamber. Opening the exhaust valve allows air to flow from the combustion chamber to an exhaust manifold. If, based on the combustion event data, a single pre-ignition (SPI) event is detected in at least one of the cylinders, a command is issued to a variable valve timing (VVT) system to implement valve timing overlap for each of the plurality of cylinders, simultaneously opening the cylinder's intake and exhaust valves to their open positions during the valve timing overlap.

Description

[0001] The technical field generally refers to vehicles and in particular to systems and procedures for managing exhaust gas composition during stochastic pre-ignition limitation.

[0002] Stochastic pre-ignition (SPI) (also known as low-speed pre-ignition (LSPI) or "superknock") is a combustion event that occurs when an air-fuel mixture introduced into a cylinder of an internal combustion engine (ICE) ignites before a spark plug fires. An SPI event typically occurs due to high temperature / pressure at the end of the compression stroke. SPI events can occur in turbocharged, direct-injection vehicles operating at low speeds and high loads. SPI events can also be triggered by oil droplets acting as the combustion initiation point, in which case the SPI event would be a function of temperature / pressure / time, as opposed to hot-spot pre-ignition. In some cases, SPI events can occur due to localized pockets of high enthalpy in an air-fuel mixture.

[0003] Additional fuel is often injected into the cylinders to create a rich air-fuel mixture, which mitigates SPI events and prevents further SPI occurrences during enrichment. The additional fuel in the rich air-fuel mixture typically lowers cylinder temperatures due to the latent heat of vaporization. As a result, flame temperatures are lower, exhaust gas temperatures are lower, and consequently, residual gas temperatures are also lower. However, burning rich air-fuel mixtures generally produces rich exhaust gases and can lead to increased emissions.

[0004] JP 2012-145 040 A describes an engine comprising a variable intake valve train, a variable exhaust valve train, a turbocharger, an intake pressure sensor, an exhaust pressure sensor, a cylinder pressure sensor, and the like. If pre-ignition is detected in any cylinder and the intake pressure is higher than the exhaust pressure, a control unit increases the overlap time of the intake and exhaust valves, for example, in the cylinder that first enters the exhaust stroke after the pre-ignition is detected.

[0005] JP 2016-125 350 A describes a control device comprising a cylinder pressure sensor with a pressure-sensitive part extending into a cylinder, and a control unit for controlling the operating state of an internal combustion engine. During the combustion engine's power strokes, the control unit detects a mass combustion rate at a specific crankshaft angle, which takes into account the influence of thermal expansion occurring in the pressure-sensitive part of the cylinder pressure sensor. If an increase in the influence of thermal expansion (a decrease in the mass combustion rate) is detected based on the mass combustion rate, the control unit executes an ignition pre-control to suppress the occurrence of pre-ignition.

[0006] It can be considered a task to specify systems and procedures for managing the exhaust gas composition during stochastic pre-ignition.

[0007] The problem is solved by a method according to claim 1 and a system according to claim 5. Furthermore, an application case of the system is described, wherein a vehicle incorporates the system.

[0008] An inventive method for managing exhaust gas composition comprises receiving combustion event data from at least one combustion event sensor assigned to a plurality of cylinders, each of the plurality of cylinders comprising: a combustion chamber; an inlet valve configured to be moved from an open position to allow a first airflow from an intake manifold to the combustion chamber and a closed position to block the first airflow from the intake manifold to the combustion chamber; and an exhaust valve configured to be moved from an open position to allow a second airflow from the combustion chamber to an exhaust manifold and a closed position to block the second airflow from the combustion chamber to the exhaust manifold.The procedure further comprises: determining whether a SPI event has occurred in at least one of the plurality of cylinders based on the combustion event data; and issuing a first command to a variable valve timing (VVT) system to implement valve timing overlap for each of the plurality of cylinders, whereby the cylinder's intake and exhaust valves are simultaneously opened during the valve timing overlap. Furthermore, a quantity of intake air enters the combustion chamber of each of the cylinders from the intake manifold via the associated intake valve, and a bypass portion of the intake air passes through the combustion chamber into the exhaust manifold via the associated exhaust valve during the valve timing overlap.The method according to the invention further comprises issuing a second command to the VVT ​​system to close the exhaust valve of each of the cylinders after the valve control overlap, whereby an enclosed portion of the intake air volume remains in the combustion chamber of the cylinder, wherein the enclosed portion of the intake air volume is less than a standard air volume used during a normal combustion process.The method according to the invention further comprises issuing a third command to a fuel injection system to inject a standard quantity of fuel, which is associated with the normal combustion process, into the combustion chambers of each of the cylinders, wherein a combination of the enclosed part of the intake air volume and the standard quantity of fuel produces a rich air-fuel mixture, wherein the rich air-fuel mixture is richer than a standard air-fuel mixture produced by a combination of the standard air volume and the standard quantity of fuel used during the normal combustion process.

[0009] In one embodiment, the method further comprises issuing a fourth command to the VVT ​​system to open the exhaust valve of each of the cylinders after the combustion of the rich air-fuel mixture in the combustion chamber of the cylinder, so that the exhaust gases produced by the combustion of the rich air-fuel mixture can flow from the combustion chamber through the associated exhaust valve into the exhaust manifold and combine with the bypass portion of the intake air volume produced by at least one of the plurality of cylinders in the exhaust manifold to form a stoichiometric exhaust gas composition.

[0010] In one embodiment, the method further comprises issuing the first command to the variable valve timing (VVT) system to maintain valve timing overlap during twenty consecutive 360° crankshaft revolutions of a vehicle's crankshaft.

[0011] In one embodiment, the method further comprises: receiving updated combustion event data from the at least one combustion event sensor after the twenty consecutive 360° crankshaft revolutions; determining whether the SPI event has been resolved based on the updated combustion event data; and issuing a fifth command to the VVT ​​system to gradually transition from valve timing overlap to a standard timing setting associated with a normal combustion process over a predefined number of consecutive crankshaft revolutions, based on the determination.

[0012] A system according to the invention for managing the exhaust gas composition comprises at least one processor and at least one memory which is communicatively connected to the at least one processor.The at least one memory contains instructions which, when executed by the at least one processor, cause the at least one processor to receive combustion event data from at least one combustion event sensor associated with a plurality of cylinders, each of the plurality of cylinders comprising: a combustion chamber; an intake valve configured to be moved from an open position to allow a first airflow from an intake manifold to the combustion chamber and a closed position to block the first airflow from the intake manifold to the combustion chamber; and an exhaust valve configured to be moved from an open position to allow a second airflow from the combustion chamber to an exhaust manifold and a closed position to block the second airflow from the combustion chamber to the exhaust manifold.The at least one memory contains instructions which, when executed by the at least one processor, cause the at least one processor to: determine, based on the combustion event data, whether an SPI event has occurred in at least one of the plurality of cylinders; and issue a first instruction to a variable valve timing (VVT) system to implement valve timing overlap for each of the plurality of cylinders, whereby the intake and exhaust valves of the cylinder are simultaneously opened during the valve timing overlap. Furthermore, a quantity of intake air from the intake manifold enters the combustion chamber of each of the cylinders via the associated intake valve, and a bypass portion of the intake air passes through the combustion chamber into the exhaust manifold via the associated exhaust valve during the valve timing overlap.The at least one memory further comprises instructions which, when executed by the at least one processor, cause it to issue a second instruction to the VVT ​​system to close the exhaust valve of each of the cylinders after the valve timing overlap, leaving a trapped portion of the intake air volume in the combustion chamber of the cylinder, the trapped portion of the intake air volume being less than a standard air volume used during a normal combustion process.The at least one memory further comprises instructions which, when executed by the at least one processor, cause it to issue a third instruction to a fuel injection system to inject a standard quantity of fuel, associated with the normal combustion process, into the combustion chambers of each of the cylinders, wherein a combination of the enclosed portion of the intake air volume and the standard quantity of fuel produces a rich air-fuel mixture, wherein the rich air-fuel mixture is richer than a standard air-fuel mixture produced by a combination of the standard air volume and the standard quantity of fuel used during the normal combustion process.

[0013] In one embodiment, the at least one memory further contains instructions which, when executed by the at least one processor, cause the at least one processor to issue a fourth instruction to the VVT ​​system to open the exhaust valve of each of the cylinders after the combustion of the rich air-fuel mixture in the combustion chamber of the cylinder, so that the exhaust gases produced by the combustion of the rich air-fuel mixture can flow from the combustion chamber through the associated exhaust valve into the exhaust manifold and combine with the bypass portion of the intake air volume produced by at least one of the plurality of cylinders in the exhaust manifold to produce a stoichiometric exhaust gas composition.

[0014] In one embodiment, the at least one memory further contains instructions which, when executed by the at least one processor, cause it to issue the first instruction to the variable valve timing system, VVT, to maintain the valve timing overlap during twenty consecutive 360° crankshaft revolutions of a crankshaft of the vehicle.

[0015] In one embodiment, the at least one memory further contains instructions which, when executed by the at least one processor, cause the at least one processor to: receive updated combustion event data from the at least one combustion event sensor after the twenty consecutive 360° crankshaft revolutions; determine, based on the updated combustion event data, whether the SPI event has been resolved; and issue a fifth instruction to the VVT ​​system to gradually transition from valve control overlap to standard control, which is associated with a normal combustion process over a predefined number of consecutive crankshaft revolutions, based on the determination.

[0016] In one application of the system according to the invention, a vehicle has the system according to the invention.

[0017] The exemplary embodiments are described below in conjunction with the following drawings, where the same numbers denote the same elements: Fig. Figure 1 is a functional block diagram of a vehicle with a system for controlling exhaust gas composition; Fig. Figure 2 is a functional block diagram of a control system with an exhaust gas composition management system; Fig. Figure 3 is a functional block diagram of a cylinder; Fig. Figure 4 is a flowchart representation of an exemplary procedure for managing exhaust gas composition during stochastic pre-ignition (SPI); and Fig. Figure 5 is a graphical representation of a valve control overlap.

[0018] As used herein, the term module refers to an application-specific integrated circuit (ASIC), an electronic circuit, a processor (common, dedicated or group) and memory executing one or more software or firmware programs, a combinational logic circuit and / or other suitable components providing the described functionality.

[0019] Embodiments of the present disclosure can be described herein in the form of functional and / or logical block components and various processing steps. Such block components can be implemented by any number of hardware, software, and / or firmware components configured to perform the specified functions. For example, an embodiment of the present disclosure may employ various integrated circuit components, such as memory elements, digital signal processing elements, logic elements, lookup tables, or the like, which, under the control of one or more microprocessors or other devices, can perform a variety of functions.Furthermore, the person skilled in the art will recognize that embodiments of the present disclosure can be used in conjunction with any number of systems and that the systems described here are merely exemplary embodiments of the present disclosure.

[0020] For the sake of brevity, conventional techniques related to signal processing, data transmission, signaling, control, and other functional aspects of the systems (and the individual components of the systems) are not described in detail here. Furthermore, the connecting lines shown in the various figures are intended to represent exemplary functional relationships and / or physical couplings between the different elements. It should be noted that in an embodiment of the present disclosure, many alternative or additional functional relationships or physical connections may exist.

[0021] In Fig. Figure 1 shows a functional block diagram of a vehicle with an exhaust gas composition management system 100 according to at least one embodiment. The vehicle 10 generally comprises a chassis 12, a body 14, front wheels 16, and rear wheels 18. While the vehicle 10 is depicted as a passenger car in the embodiment shown, it can also be other vehicle types such as trucks, sport utility vehicles (SUVs), crossover vehicles (CUVs), and motorhomes (RVs).

[0022] In various embodiments, the body 14 is arranged on the chassis 12 and essentially encloses components of the vehicle 10. The body 14 and the chassis 12 can together form a frame. The wheels 16, 18 are each rotatably connected to the chassis 12 near a corner of the body 14.

[0023] In various embodiments, the vehicle 10 is an autonomous or semi-autonomous vehicle that is automatically controlled to transport passengers and / or cargo from one place to another. In one exemplary embodiment, the vehicle 10 is a so-called Level 2, Level 3, Level 4, or Level 5 automation system. Level 2 automation means that the vehicle assists the driver with various driving tasks under the driver's supervision. Level 3 automation means that, under certain circumstances, the vehicle can take over all driving functions. All major functions are automated, including braking, steering, and accelerating. At this level, the driver can completely relinquish control until the vehicle instructs them otherwise. A Level 4 system signifies a "high degree of automation," meaning that the vehicle can operate the vehicle independently without any intervention.An automated driving system performs all aspects of the dynamic driving task, even if a human driver does not respond appropriately to a request for intervention. A Level 5 system means "full automation," i.e., an automated driving system fully performs all aspects of the dynamic driving task under all road and environmental conditions that a human driver could handle.

[0024] As shown, the vehicle 10 generally comprises a drive system 20, a transmission system 22, a steering system 24, a braking system 26, a sensor system 28, an actuator system 30, at least one data storage device 32, at least one controller 34, and a communication system 36. The controller 34 is configured to implement an automated driving system (ADS). The drive system 20 is configured to generate energy for propelling the vehicle. In various embodiments, the drive system 20 may include an internal combustion engine (ICE). The transmission system 22 is configured to transmit the power of the drive system 20 to the wheels 16, 18 of the vehicle according to selectable speed ratios. In various embodiments, the transmission system 22 may include a continuously variable automatic transmission (CVT), a continuously variable transmission (CVT), or another suitable transmission.The braking system 26 is configured to exert a braking torque on the vehicle wheels 16, 18. The braking system 26 can, in various embodiments, include friction brakes, a wire-operated brake, a regenerative braking system such as an electric machine, and / or other suitable braking systems.

[0025] The steering system 24 is configured to influence the position of the vehicle wheels 16. For illustration, the steering system 24 is shown to include a steering wheel and a steering column; however, in some embodiments considered within the scope of this disclosure, the steering system 24 may not include a steering wheel and / or a steering column. The steering system 24 includes a steering column coupled to an axle 50 associated with the front wheels 16, for example, via a rack and pinion or another mechanism (not shown). Alternatively, the steering system 24 may include a steering wheel system containing actuators associated with each of the front wheels 16.

[0026] The sensor system 28 comprises one or more detection devices 40a-40n that detect observable conditions of the external environment and / or the internal environment of the vehicle 10. The detection devices 40a-40n may include, but are not limited to, radars, lidar, global positioning systems, optical cameras, thermal cameras, ultrasonic sensors, a steering wheel sensor and / or other sensors.

[0027] The vehicle dynamics sensors provide data on vehicle dynamics, including longitudinal speed, yaw rate, lateral acceleration, longitudinal acceleration, etc. The vehicle dynamics sensors can include wheel sensors that measure information about one or more wheels of the vehicle 10. In one embodiment, the wheel sensors have wheel speed sensors coupled to each of the wheels 16, 18 of the vehicle 10. Furthermore, the vehicle dynamics sensors can include one or more accelerometers (as part of an inertial measurement unit (IMU)) that measure information about the acceleration of the vehicle 10. In various embodiments, the accelerometers measure one or more acceleration values ​​for the vehicle 10, including lateral and longitudinal acceleration and yaw rate. In at least one embodiment, the vehicle dynamics sensors provide vehicle motion data.

[0028] The actuator system 30 comprises one or more actuator devices 42a-42n that control one or more vehicle features, such as, but not limited to, one or more vehicle wheels 16, 18, the drive system 20, the transmission system 22, the steering system 24, and the braking system 26. In various embodiments, the vehicle features may also include interior and / or exterior features of the vehicle, such as doors, a trunk, and cabin features such as air conditioning, music, lighting, etc. (not numbered).

[0029] The communication system 36 is configured to wirelessly transmit information to and from other entities 48, such as other vehicles (“V2V” communication), infrastructure (“V2I” communication), remote systems, and / or personal devices. In one exemplary embodiment, the communication system 36 is a wireless communication system configured to communicate via a wireless local area network (WLAN) using IEEE 802.11 standards or via cellular data communication. However, additional or alternative communication methods, such as a dedicated short-range communication channel (DSRC), are also considered within the scope of this disclosure.DSRC channels refer to one- or two-way short- to medium-range wireless communication channels specifically designed for use in motor vehicles, as well as a range of protocols and standards.

[0030] The device 32 stores data for use in the ADS of the vehicle 10. In various embodiments, the device 32 stores defined maps of the navigable environment. In various embodiments, the defined maps can be predefined by and obtained from a remote system. For example, the defined maps can be compiled by the remote system and transmitted to the vehicle 10 (wirelessly and / or via a wired connection) and stored in the data storage device 32. As can be seen, the data storage device 32 can be part of the controller 34, separate from the controller 34, or part of the controller 34 and part of a separate system.

[0031] The controller 34 comprises at least one processor 44 and a computer-readable device or medium 46. The processor 44 can be any custom or commercially available processor, a central processing unit (CPU), a graphics processing unit (GPU), an auxiliary processor among several processors associated with the controller 34, a semiconductor-based microprocessor (in the form of a microchip or chipset), a macroprocessor, any combination thereof, or generally any device for executing instructions. The computer-readable devices or media 46 can include volatile and non-volatile memory, such as read-only memory (ROM), random-access memory (RAM), and keep-alive memory (KAM). KAM is persistent or non-volatile memory that can be used to store various operating variables while the processor 44 is powered off.The computer-readable storage device or computer-readable storage medium 46 can be implemented using any number of known storage devices such as PROMs (programmable read-only memory), EPROMs (electrically erasable PROMs), EEPROMs (electrically erasable PROMs), flash memory, or other electrical, magnetic, optical, or combined storage devices capable of storing data, some of which constitute executable instructions used by the controller 34 in controlling the vehicle 10. In at least one embodiment, the computer-readable device 46 is at least one memory configured to store the exhaust composition management system 100.

[0032] The instructions can comprise one or more separate programs, each containing an ordered list of executable instructions for implementing logical functions. When executed by the processor 44, the instructions receive and process signals from the sensor system 28, perform logic, calculations, procedures, and / or algorithms for the automatic control of the vehicle 10 components, and generate control signals for the actuator system 30 to automatically control the vehicle 10 components based on the logic, calculations, procedures, and / or algorithms. Although in Fig. While only one controller 34 is shown in Figure 1, embodiments of the vehicle 10 may include any number of controllers 34 that communicate via any suitable communication medium or combination of communication media and cooperate to process the sensor signals, perform logic, calculations, procedures and / or algorithms, and generate control signals to automatically control features of the vehicle 10. In various embodiments, the controller(s) 34 are configured to implement ADS.

[0033] In Fig. Figure 2 shows a functional block diagram of a controller 34 with an exhaust gas composition management system 100 according to at least one embodiment. The controller 34 comprises at least one processor 44 and at least one memory 46. The at least one processor 44 is a programmable device containing one or more instructions that are stored in or assigned to the at least one memory 46. The at least one memory 46 contains instructions for the execution of which the at least one processor 44 is configured. The at least one memory 46 contains an embodiment of the exhaust gas composition management system 100, which is configured to manage the exhaust gas composition during stochastic pre-ignition (SPI) reduction.

[0034] The control unit 34 is configured to be communicatively coupled to at least one combustion event sensor 200. The vehicle 10 comprises a plurality of cylinders (not shown). The combustion event sensor(s) 200 is / are assigned to the plurality of cylinders. In at least one embodiment, each combustion sensor 200 is assigned to at least two cylinders. In at least one embodiment, each combustion sensor 200 is assigned to four cylinders. The control unit 34 is configured to receive combustion event data from the combustion event sensor(s) 200. In at least one embodiment, the combustion event sensor(s) 200 are knock sensors. In at least one embodiment, the combustion event sensor(s) 200 are standard versions of cylinder pressure sensors.The control unit 34 is configured to determine, based on the combustion event data received from the combustion event sensor(s) 200, whether an SPI event has occurred in a cylinder.

[0035] The control unit 34 is configured to communicate with a variable valve timing (VVT) system 202. Each cylinder is fluidically connected to an intake manifold via an intake valve and to an exhaust manifold via an exhaust valve. The VVT ​​system 202 is configured to control and adjust the timing of the opening and closing of the intake and exhaust valves of each cylinder. The opening and closing of a valve is also referred to as a valve lift event. The control unit 34 is configured to communicate with a fuel injection system 204. The fuel injection system 204 controls the injection of fuel into the cylinders. The operation of the exhaust gas composition management system 100 is described in more detail below.

[0036] In Fig. Figure 3 shows a functional block diagram of a cylinder 300 according to at least one embodiment. The exhaust gas composition management system 100 is configured to manage the composition of the exhaust gases generated by the cylinder 300 during SPI reduction in response to the detection of an SPI event at the cylinder 300. The cylinder 300 comprises a combustion chamber 302, a piston 304, an inlet valve 306, an exhaust valve 308, and a fuel injector 310.

[0037] The intake valve 306 can be positioned in either an open or a closed position. When the intake valve 306 is in the open position, an airflow 312 is released from an intake manifold 314 of the vehicle 10 to the combustion chamber 302. When the intake valve 306 is in the closed position, the airflow 312 from the intake manifold 314 to the combustion chamber 302 is blocked. The exhaust valve 308 can be positioned in either an open or a closed position. When the exhaust valve 308 is in the open position, an airflow 316 is released from the combustion chamber 302 to an exhaust manifold 318 of the vehicle 10. When the exhaust valve 308 is in the closed position, the airflow 316 from the combustion chamber 302 to the exhaust manifold 318 is blocked.One or more combustion event sensors 200 (not shown) are configured to capture combustion event data assigned to cylinder 300.

[0038] A vehicle 10 comprises a multitude of cylinders 300. A VVT system 202 manages the timing control assigned to the opening and closing of the intake valves 306 and the exhaust valves 308 of each cylinder 300. The VVT ​​system 202 implements a standard control that is assigned to the opening and closing of the intake valves 306 and the exhaust valves 308 of each cylinder 300 during a normal combustion process. When the exhaust composition management system 100 detects the occurrence of a SPI event in one of the cylinders 300, the exhaust composition management system 100 issues a command to the VVT ​​system 202 to implement valve timing overlap in all cylinders 300 during an SPI event mitigation process, so that exhaust gas with a stoichiometric composition is produced and expelled from the vehicle 10 via the exhaust manifold 318.

[0039] In Fig. Figure 4 is a flowchart of an exemplary method 400 for managing the exhaust gas composition during stochastic pre-ignition (SPI) according to at least one embodiment. The method 400 is described with reference to an exemplary implementation of an embodiment of an exhaust gas composition management system 100. As can be seen from the disclosure, the sequence of the method 400 is not limited to the one described in Figure 4. Fig. The sequential execution shown in section 4 is limited, but can be carried out in one or more varying sequence(s), depending on applicability and in accordance with the present disclosure.

[0040] In 402, the exhaust gas composition management system 100 receives combustion event data from the combustion event sensor(s) 200. A vehicle 10 comprises a plurality of cylinders 300. The combustion event sensor(s) 200 is / are configured to receive combustion event data associated with the plurality of cylinders 300. In at least one embodiment, the combustion event sensor(s) 200 are knock sensors. In 404, the exhaust gas composition management system 100 determines, based on the combustion event data received from the combustion event sensor(s) 200, whether a SPI event has occurred in any of the cylinders 300. If the exhaust gas composition management system 100 determines that no SPI event has occurred in any of the cylinders 300, the process 400 returns to 402.

[0041] When the exhaust composition management system 100 detects that an SPI event has occurred in one of the cylinders 300, it issues a command to a VVT system 202 to implement a valve timing overlap at 406. The VVT ​​system 202 is configured to manage the timing associated with opening and closing the intake valves 306 and exhaust valves 308 of each cylinder 300. The VVT ​​system 202 sets the timing so that the intake valve 306 and the exhaust valve 308 of the cylinders 300 are simultaneously brought to open positions during the valve timing overlap at 408.

[0042] In Fig. Figure 5 shows a graphical representation of a valve timing overlap 500 according to at least one embodiment. The x-axis of the diagram represents the crank angle and the y-axis represents the lift in millimeters of an intake valve 306 and an exhaust valve 308 as a function of the crank angle in a cylinder 300. Curve 502 represents the lift of the exhaust valve 308 as a function of the crank angle during a normal combustion process. Curve 504 represents the lift of the intake valve 308 as a function of the crank angle during the normal combustion process. Curve 506 represents the lift of the intake valve 306 as a function of the crank angle during the execution of a valve timing overlap 500. Curve 506 represents the exhaust valve lift in a delayed phase that allows for overlap with the intake valve lift.It is also possible to make the inlet valve event 504 occur earlier in this example, which can allow for greater valve control overlap, thereby increasing the scavenging amount.

[0043] The timing of the intake valve 306 was set to generate the valve timing overlap 500. In at least one embodiment, the timing of the exhaust valve 308 can be set to generate the valve timing overlap 500. In at least one embodiment, the timing of both the intake valve 306 and the exhaust valve 308 can be set to generate the valve timing overlap 500. During the valve timing overlap 500, the intake valve 306 and the exhaust valve 308 of cylinder 300 are simultaneously brought into open positions. There is a continuum of open positions for the intake valve 306 and the exhaust valve 308 as a cam rotates, so that neither the intake valve 306 nor the exhaust valve 308 is fully open during the valve timing overlap. There is a certain intermediate stroke between the inlet valve 306 and the exhaust valve 308.During the valve timing overlap 500, both the intake valve 306 and the exhaust valve 308 share an overlapping opening time. The strategy for mitigating the SPI event utilizes the degree of valve timing overlap 500 between the intake valve 306 and the exhaust valve 308 to increase the scavenging air into the exhaust, thereby enriching the trapped air-fuel mixture in the cylinder.

[0044] Back to Fig.4: After the intake valve 306 and the exhaust valve 308 are simultaneously moved to the open positions, a volume of intake air enters the combustion chamber 302 from the intake manifold 314 via the open intake valve 306 at 410. At 412, a bypass portion of the intake air volume flows through the combustion chamber 302 via the open exhaust valve 308 into the exhaust manifold 318. At 414, the exhaust composition management system 100 sends a command to the VVT ​​system 202 to close the intake valve 306 and the exhaust valve 308. The exhaust valve 308 closes first, and the intake valve 306 remains open to complete the intake stroke. When the inlet valve 306 and the exhaust valve 308 are in the closed position, part of the intake air volume remains trapped in the combustion chamber 302 at 416.During a normal combustion process, the VVT ​​system 202 timing the opening and closing of the inlet valve 306 and the exhaust valve 308, resulting in a standard volume of air remaining in the combustion chamber 302 for use in the combustion process. The portion of the intake air volume trapped in the combustion chamber 302 is less than the standard air volume. In at least one embodiment, the total intake air volume is equal to the standard air volume. The sum of the bypass portion of the intake air volume in the exhaust manifold 318 and the portion of the intake air volume trapped in the combustion chamber 302 is equal to the standard air volume.In at least one embodiment, the sum of the bypass portion of the intake air volume in the exhaust manifold 318 and the trapped portion of the intake air volume in the combustion chamber 302 varies based on the air that must be trapped in the cylinder 300 to keep the engine load within a tolerance band. The trapped portion of the intake air volume in the combustion chamber 302 is used during the combustion process during the SPI reduction process. The engine control unit (ECU) will typically meter the fuel based on what is measured by an air mass sensor upstream of the intake manifold 314 during normal operation, with the standard air volume being based on the reading provided by the air mass sensor.

[0045] At 418, the exhaust gas composition management system 100 issues a command to the fuel injection system 204 to inject the standard amount of fuel used during the normal combustion process into the combustion chamber 302 of cylinder 300. During the normal combustion process, the standard volume of air combines with the standard amount of fuel to create a normal air-fuel mixture. Because the trapped portion of the intake air volume is less than the standard air volume, the combination of the standard amount of fuel and the trapped portion of the intake air volume results in a rich air-fuel mixture, which is richer than the normal air-fuel mixture.

[0046] At cylinder 420, the combustion of the rich air-fuel mixture takes place in combustion chamber 302 of cylinder 420. The combustion of rich air-fuel mixtures is generally used to mitigate SPI (Single Point Injection) events in cylinder 300. However, the combustion of rich air-fuel mixtures typically produces rich exhaust gases that do not meet the stoichiometric exhaust gas composition required for compliance with emission limits.

[0047] At 422, the exhaust gas composition management system 100 sends a command to the VVT ​​system 202 to open the exhaust valve 308 of cylinder 300. The rich exhaust gases produced during the combustion of the rich air-fuel mixture flow from the combustion chamber 302 of cylinder 300 through the open exhaust valve 308 into the exhaust manifold 318. At 424, the rich exhaust gases mix with the bypass sections of the intake air volumes assigned to one or more of the cylinders 300 in the exhaust manifold 318 to create a stoichiometric exhaust gas composition for emission via the vehicle's exhaust system 10. The bypass sections of the intake air in the exhaust manifold 318 dilute the rich exhaust gases produced during the combustion of the rich air-fuel mixture to create the stoichiometric exhaust gas composition. The stoichiometric exhaust gas composition is processed by a catalytic converter before being expelled from the vehicle 10.

[0048] In at least one embodiment, the exhaust gas composition management system 100 issues a command to the VVT ​​system 202 to maintain the valve timing overlap 500 for twenty consecutive 360° crankshaft revolutions of a crankshaft of the vehicle 10. After the twenty consecutive 360° crankshaft revolutions, the exhaust gas composition management system 100 receives updated combustion event data from the combustion event sensor(s) 200. Based on the updated combustion event data, the exhaust gas composition management system 100 determines whether the SPI event has been resolved.

[0049] When the exhaust composition management system (100) detects that the SPI event has resolved, it issues a command to the VVT ​​system (202) to gradually transition from valve timing overlap 500 to standard control, which is associated with the normal combustion process, over a predefined number of consecutive crankshaft revolutions. If the exhaust composition management system (100) detects that the SPI event has not resolved, valve timing overlap 500 is maintained for a further twenty consecutive 360° crankshaft revolutions of the vehicle's crankshaft (10).

[0050] The twenty consecutive 360° crankshaft revolutions constitute ten cycles. In alternative embodiments, the exhaust gas composition management system 100 can instruct the VVT ​​system 202 to maintain the valve timing overlap 500 for a different number of consecutive 360° crankshaft revolutions of the vehicle 10's crankshaft. In at least one embodiment, the number of consecutive 360° crankshaft revolutions for which the valve timing overlap 500 is maintained is calibrated. In at least one embodiment, the exhaust gas composition management system 100 can instruct the VVT ​​system 202 to maintain the valve timing overlap 500 for a predefined number of consecutive 360° crankshaft revolutions of the vehicle 10's crankshaft.

Claims

[1] Method (400) for managing exhaust gas composition, comprising: Receiving combustion event data from at least one combustion event sensor (200) assigned to a plurality of cylinders (300), each of which comprises: a combustion chamber (302); an inlet valve (306) configured to be moved from an open position to allow an initial airflow (312) from an intake manifold (314) to the combustion chamber (302), and a closed position to block the initial airflow (312) from the intake manifold (314) to the combustion chamber (302); and an exhaust valve (308) configured to be moved from an open position to allow a second airflow (316) from the combustion chamber (302) to an exhaust manifold (318) and a closed position to block the second airflow (316) from the combustion chamber (302) to the exhaust manifold (318); Determine whether a stochastic pre-ignition (SPI) event has occurred in at least one of the plurality of cylinders (300), based on the combustion event data; and Issuing a first command to a variable valve timing (VVT) system (202) to implement a valve timing overlap for each of the plurality of cylinders (300), wherein the inlet valve (306) and the exhaust valve (308) of the cylinder (300) are brought to the open positions simultaneously during the valve timing overlap; wherein a volume of air drawn in from the intake manifold (314) enters the combustion chamber (302) of each of the cylinders (300) via the associated intake valve (306) and a bypass portion of the volume of air drawn in passes through the combustion chamber (302) into the exhaust manifold (318) via the associated exhaust valve (308) during the valve timing overlap; the procedure (400) further comprises: Issuing a second command to the VVT ​​system (202) includes closing the exhaust valve (308) of each of the cylinders (300) after the valve timing overlap, leaving a trapped portion of the intake air volume in the combustion chamber (302) of the cylinder (300), the trapped portion of the intake air volume being less than a standard air volume used during a normal combustion process; and Issuing a third command to a fuel injection system (204) comprises injecting a standard quantity of fuel associated with the normal combustion process into the combustion chambers (302) of each of the cylinders (300), wherein a combination of the enclosed portion of the intake air volume and the standard quantity of fuel produces a rich air-fuel mixture, wherein the rich air-fuel mixture is richer than a standard air-fuel mixture produced by a combination of the standard air volume and the standard quantity of fuel used during the normal combustion process. [2] Method (400) according to claim 1, further comprising issuing a fourth command to the VVT ​​system (202) to open the exhaust valve (308) of each of the cylinders (300) after the combustion of the rich air-fuel mixture in the combustion chamber (302) of the cylinder (300), so that the exhaust gases produced by the combustion of the rich air-fuel mixture can flow from the combustion chamber (302) through the associated exhaust valve (308) into the exhaust manifold (318) and combine with the bypass portion of the intake air volume produced by at least one of the plurality of cylinders (300) in the exhaust manifold (318) to form a stoichiometric exhaust gas composition. [3] Method (400) according to claim 1, further comprising issuing the first command to the VVT ​​system (202) to maintain the valve control overlap during twenty successive 360° crankshaft revolutions of a crankshaft of a vehicle (10). [4] Method (400) according to claim 3, further comprising: Receiving updated combustion event data from the at least one combustion event sensor (200) after the twenty consecutive 360° crankshaft rotations; Determine whether the SPI event was resolved based on the updated combustion event data; and Issuing a fifth command to the VVT ​​system (202) to gradually transition from valve control overlap to standard control, which is associated with a normal combustion process over a predefined number of successive crankshaft revolutions, based on the determination. [5] System (100) for managing exhaust gas composition, comprising: at least one processor (44); and at least one memory (46) that is communicatively connected to the at least one processor (44), wherein the at least one memory (46) comprises instructions which, when executed by the at least one processor (44), cause the at least one processor (44) to: To receive combustion event data from at least one combustion event sensor (200) assigned to a plurality of cylinders (300), each of the plurality of cylinders (300) comprising: a combustion chamber (302); an inlet valve (306) configured to be moved from an open position to allow an initial airflow (312) from an intake manifold (314) to the combustion chamber (302), and a closed position to block the initial airflow (312) from the intake manifold (314) to the combustion chamber (302); and an exhaust valve (308) configured to be moved from an open position to allow a second airflow (316) from the combustion chamber (302) to an exhaust manifold (318), and a closed position to block the second airflow (316) from the combustion chamber (302) to the exhaust manifold (318); to determine whether a stochastic pre-ignition (SPI) event has occurred in at least one of the plurality of cylinders (300) (300), based on the combustion event data; and to issue a first command to a variable valve timing (VVT) system (202) to implement a valve timing overlap for each of the plurality of cylinders (300), whereby the inlet valve (306) and the exhaust valve (308) of the cylinder (300) are brought into the open positions simultaneously during the valve timing overlap; wherein a volume of air drawn in from the intake manifold (314) enters the combustion chamber (302) of each of the cylinders (300) via the associated intake valve (306) and a bypass portion of the volume of air drawn in passes through the combustion chamber (302) into the exhaust manifold (318) via the associated exhaust valve (308) during the valve timing overlap; wherein the at least one memory (46) further comprises instructions which, when executed by the at least one processor (44), cause it to issue a second instruction to the VVT ​​system (202) to close the exhaust valve (308) of each of the cylinders (300) after the valve timing overlap, leaving a trapped portion of the intake air volume in the combustion chamber (302) of the cylinder (300), the trapped portion of the intake air volume being less than a standard air volume used during a normal combustion process; and wherein the at least one memory (46) further comprises instructions which, when executed by the at least one processor (44), cause it to issue a third instruction to a fuel injection system (204) to inject a standard quantity of fuel associated with the normal combustion process into the combustion chambers (302) of each of the cylinders (300), wherein a combination of the enclosed portion of the intake air volume and the standard quantity of fuel produces a rich air-fuel mixture, wherein the rich air-fuel mixture is richer than a standard air-fuel mixture produced by a combination of the standard air volume and the standard quantity of fuel used during the normal combustion process.

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