System and method for bypassing a particulate filter

Methods and systems are provided for an emission control device for an engine system including a gasoline particulate filter (GPF) and bypass passage for the GPF. In one example, the system may include a converging cone to direct exhaust flow through a central bypass passage, housing a valve, which originates upstream of the GPF and eventually passes through the center of it (thereby bypassing the GPF). In another example exhaust flow may travel through outer passages, coupled between the converging cone and GPF and spaced around the central bypass passage, to travel to the GPF.

FIELD

The present description relates generally to methods and systems for an exhaust after treatment system of a motor vehicle.

Some internal combustion engines employ a gasoline particulate filter (GPF) in an exhaust system to trap particulate matter flowing through the exhaust system and thereby meet emission standards. GPFs may be constructed of porous ceramics, or other porous materials. Regardless of the specifics of the design, the purpose of the filter is to filter soot particles, the soot particles consisting of solid carbon often with adsorbed hydrocarbons, out of exhaust gas flowing through the filter and then hold the filtered soot particles within the filter until the filter is regenerated by combusting soot to form gaseous products. Soot is produced in a gasoline engine primarily in the first few minutes following cold start. In addition to soot, the exhaust gas also carries incombustible solid material, which may be referred to as ash, which may also be trapped by the GPF. However, since the ash is incombustible, it may remain in the filter for its useful life. Ash is derived primarily from lubricating oil entering the combustion chamber or exhaust ports. Other sources include corrosion from the exhaust manifold and debris from the upstream catalytic converter. Ash is produced during all engine operating modes. As particulate matter (e.g., ash and soot) accumulates in a particulate filter (e.g., the GPF), exhaust backpressure may increase, which can adversely affect fuel economy. While actively regenerating the GPF may remove the stored soot, the stored ash may remain within the filter after regeneration, and thus the exhaust backpressure created by the GPF may only partially be reduced. As such, the ash may continue to contribute to the exhaust backpressure on the engine, thereby reducing engine torque output and/or engine fuel economy.

Other attempts to address particulate matter build-up within a GPF include employing a bypass system that bypasses exhaust flow around the GPF. Specifically, the bypass system may include a bypass passage in parallel with the GPF and a valve disposed within the bypass passage for controlling flow through the bypass passage. One example approach is shown by Gonze et al. in U.S. Patent Application No. 2012/0060482. Therein, Gonze discloses methods of regenerating a gasoline particulate filter (GPF) in a spark-ignition engine. Gonze also discloses a GPF bypass apparatus for the GPF wherein an annular channel extends through the central axis of the GPF. The portion of the annular channel which is closest to the upstream catalytic converter (i.e., where exhaust first comes into contact with the GPF and channel) is outfitted with an operable valve to direct exhaust gasses during various operating conditions of the vehicle.

Another example approach is shown by Kono et al in U.S. Pat. No. 4,974,414 and Arai et al in U.S. Pat. No. 5,105,619 which also disclose methods and systems for regenerating a particulate filter in a spark-ignition engine. Both references employ a bypass passage around a GPF, the bypass passage including a valve with a portion of the valve arranged external to the bypass passage. The bypass passage runs parallel to and outside of the GPF, adjacent to the GPF.

However, the inventors herein have recognized potential issues with such systems. As one example, the valve situated at the mouth of the annular passage (e.g., within the GPF enclosure, as shown in Gonze) makes access to said valve for repair/replacement difficult, and traps heat within the system, posing a challenge to component durability. As another example, bypass passages located adjacent and parallel to the GPF enclosure increase the diameter and/or width of the system, thereby increasing the total packaging space of the GPF system and emission control devices.

As one example, the issues described above may be addressed by an apparatus including a gasoline particulate filter (GPF) arranged in an exhaust passage, a central bypass passage including a first portion disposed upstream of the GPF and a second portion passing through a center of the GPF, a converging cone forming a portion of the exhaust passage and arranged upstream of and connecting to the first portion, one or more outer passages coupled between the converging cone and the GPF and spaced away from the central bypass passage, and a valve arranged within the first portion. In this way, packing size of an exhaust system including the GPF may be reduced and the valve in the central bypass passage may be more easily accessed for repair and/or replacement.

DETAILED DESCRIPTION

The following description relates to systems and methods for an emission control device including a gasoline particulate filter (GPF) in an engine system, such as the engine system shown inFIG. 1. As shown inFIG. 1, the emission control device may be arranged downstream of engine cylinders of an engine of the engine system, in an exhaust passage of the engine system. The GPF filters particulate matter from exhaust gases flowing through the exhaust passage before exiting the engine system. However, while some of these particles (e.g., soot) may be removed from the filter via regeneration events, other non-combustible particles (such as ash) may remain within the GPF for a lifetime of the filter, thereby increasing a pressure drop across the GPF and subsequently increasing an exhaust backpressure on the engine. Thus, the emission control device may include a bypass passage which allows exhaust gases from the engine cylinders to bypass the GPF under certain engine operating conditions (e.g., such as when ash may be flowing through the exhaust passage or during conditions of reduced soot production).FIGS. 2A-2Bshow an example of such an emission control device where the bypass passage is a central bypass passage that extends through a center of the GPF. As shown inFIGS. 2A-2B, the central bypass passage includes a valve adjustable via a controller of the engine system to selectively allow a different percentage of exhaust gases to pass through the GPF (via a plurality of peripheral passages positioned around the central bypass passage) or bypass the GPF through the bypass passage. As shown in a cross-section of the emission control device ofFIGS. 2A-2B, depicted inFIG. 3, the peripheral passages and central bypass passage may be spaced apart from one another while still being positioned within an outer diameter (or width) of the emission control device, as defined by a housing of the GPF and/or additional emission control devices (e.g., catalysts) of the emission control device.FIG. 4shows a flowchart illustrating a method for controlling the valve in response to a number of vehicle operating conditions. After a period of engine use, particulate matter may build-up in the GPF, thereby causing a pressure drop across the filter to increase. As a result, the controller may initiate active regeneration of the GPF to burn soot from the filter, as shown inFIG. 5. As also shown inFIG. 5, the controller may adjust a position of the valve during the regeneration event to maintain desired conditions for the regeneration event. In this way, adjusting the valve in the central bypass passage may reduce an amount of un-combustible particulate matter being stored within the GPF, thereby reducing the backpressure on the engine and increasing a longevity of the GPF. Additionally, the arrangement of the peripheral passages and central bypass passage may allow the valve to be serviced more easily while also reducing a packaging space of the emission control device within the engine system.

FIG. 1, schematically illustrates one cylinder of multi-cylinder engine10, which may be included in a propulsion system of an automobile. Engine10may be controlled at least partially by a control system including controller12and by input from a vehicle operator132via an input device130. In this example, input device130includes an accelerator pedal and a pedal position sensor134for generating a proportional pedal position signal PP. Combustion chamber (i.e., cylinder)30of engine10may include combustion chamber walls32with piston36positioned therein. In some embodiments, the face of piston36inside cylinder30may have a bowl. Piston36may be coupled to crankshaft40so that reciprocating motion of the piston is translated into rotational motion of the crankshaft. Crankshaft40may be coupled to at least one drive wheel of a vehicle via an intermediate transmission system. Further, a starter motor may be coupled to crankshaft40via a flywheel to enable a starting operation of engine10.

Combustion chamber30may receive intake air from intake manifold44via intake passage42and may exhaust combustion gases via exhaust passage48. Intake manifold44and exhaust passage48can selectively communicate with combustion chamber30via a respective intake valve52and exhaust valve54. In some embodiments, combustion chamber30may include two or more intake valves and/or two or more exhaust valves.

Intake valve52may be controlled by controller12via electric valve actuator (EVA)51. Similarly, exhaust valve54may be controlled by controller12via EVA53. Alternatively, the variable valve actuator may be electro hydraulic or any other conceivable mechanism to enable valve actuation. During some conditions, controller12may vary the signals provided to actuators51and53to control the opening and closing of the respective intake and exhaust valves. The position of intake valve52and exhaust valve54may be determined by valve position sensors55and57, respectively. In alternative embodiments, one or more of the intake and exhaust valves may be actuated by one or more cams, and may utilize one or more of cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT) and/or variable valve lift (VVL) systems to vary valve operation. For example, cylinder30may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation including CPS and/or VCT.

Fuel injector66is shown coupled directly to combustion chamber30for injecting fuel directly therein in proportion to the pulse width of signal FPW received from controller12. In this manner, fuel injector66provides what is known as direct injection of fuel into combustion chamber30. The fuel injector may be mounted in the side of the combustion chamber or in the top of the combustion chamber, for example. Fuel may be delivered to fuel injector66by a fuel system (not shown) including a fuel tank, a fuel pump, and a fuel rail.

Ignition system88can provide an ignition spark to combustion chamber30via spark plug92in response to spark advance signal SA from controller12, under select operating modes. Though spark ignition components are shown, in some embodiments, combustion chamber30or one or more other combustion chambers of engine10may be operated in a compression ignition mode, with or without an ignition spark.

Intake passage42or intake manifold44may include a throttle62having a throttle plate64. In this particular example, the position of throttle plate64, or a throttle opening, may be varied by controller12via a signal provided to an electric motor or actuator included with throttle62, a configuration that is commonly referred to as electronic throttle control (ETC). In this manner, throttle62may be operated to vary the intake air provided to combustion chamber30among other engine cylinders. The position of throttle plate64may be provided to controller12by throttle position signal TP. Intake passage42may include a mass airflow sensor120and a manifold air pressure sensor122for providing respective signals MAF and MAP to controller12.

Further, in the disclosed embodiments, an exhaust gas recirculation (EGR) system100may route a desired portion of exhaust gas from exhaust passage48to intake manifold44. In this example, high pressure (HP) EGR passage140is illustrated. The amount of EGR provided to intake manifold44may be varied by controller12via HP EGR valve142. Further, an EGR sensor144may be arranged within the HP EGR passage140and may provide an indication of one or more of pressure, temperature, and concentration of the exhaust gas. Alternatively, the EGR flow may be controlled through a calculated value based on signals from the MAF sensor (upstream), MAP (intake manifold), MAT (manifold gas temperature) and the crank speed sensor. Further, the EGR flow may be controlled based on an exhaust O2 sensor and/or an intake oxygen sensor (intake manifold). Under some conditions, the EGR system may be used to regulate the temperature of the air and fuel mixture within the combustion chamber and/or the temperature proximate to GPF72. WhileFIG. 1shows a high pressure EGR system, a low pressure EGR system may additionally, or alternatively, be used. In a low pressure EGR system, EGR may be routed from downstream of a turbine of a turbocharger to upstream of a compressor of the turbocharger, as show inFIG. 1.

As such, engine10may further include a compression device such as a turbocharger or supercharger including at least a compressor162arranged along intake manifold44. For a turbocharger, compressor162may be at least partially driven by a turbine164(e.g., via a shaft) arranged along exhaust passage48. For a supercharger, compressor162may be at least partially driven by the engine10and/or an electric machine, and may not include a turbine. Thus, the amount of compression provided to one or more cylinders of the engine via a turbocharger or supercharger may be varied by controller12.

Upstream of turbine164and coupled between exhaust passage48and a bypass passage165is a wastegate valve163. Depending on position of the wastegate valve, the amount of exhaust gas passing turbine164may be controlled. Position of wastegate valve163may be controlled via a wastegate actuator (not shown, and which may be hydraulic, pneumatic, electric, or mechanical in nature) responding to a signal from controller12. For example, the controller12may want to increase torque, and may accomplish this by increasing boost pressure. One way to increase boost pressure is to increase the amount of energy going to turbine164. For more energy to turbine164, the controller may signal the wastegate actuator to change wastegate valve163to a first position, or maintain a first position, (e.g., fully closed) that is such that no exhaust may travel through bypass passage165and all exhaust gas must pass turbine164. Conversely, to decrease boost pressure, the controller12may signal the wastegate actuator to cause the wastegate valve163to assume, or maintain, a second position (e.g., fully open) to allow a percentage of exhaust gas traveling from exhaust passage48to flow past the wastegate valve163, through bypass passage165, thereby bypassing turbine164, until the bypass passage165reconnects to exhaust passage48downstream of turbine164. It will be appreciated that wastegate valve163may assume a plurality of intermediate positions (in response to controller12signaling the wastegate actuator to change position of the wastegate valve163) residing between the first (e.g., fully closed) and second (e.g., fully open) positions, so that variable amounts of exhaust gas may travel through bypass passage165, thereby bypassing turbine164.

Exhaust gas sensor126is shown coupled to exhaust passage48upstream of emission control device (ECD)70. Exhaust gas sensor126may be any suitable sensor for providing an indication of exhaust gas air/fuel ratio such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. Although oxygen sensor14and temperature sensor16are shown in addition to exhaust gas sensor126inFIG. 1, one or more of these sensors may be omitted and/or moved.

Emission control device (ECD)70is shown arranged along exhaust passage48downstream of exhaust gas sensor126. In this example, ECD70includes a three way catalytic converter (TWC)71, a gasoline particulate filter (GPF)72, and a pressure sensor15. In some embodiments, GPF72may include one or more catalyst materials in addition to components configured to filter exhaust gas. For example, GPF72may be coated with a wash-coat including one or more catalyst materials. Such a configuration may be employed for embodiments in which engine10is spark-ignited, for example. In some embodiments, the TWC71and GPF72may be separate components comprising separate housings positioned away from one another (e.g., the TWC being upstream of the GPF as shown inFIGS. 1, 2A, and 2B), with a valve between them (not shown inFIG. 1), arranged on/in a GPF bypass passage located along a common axis. Details regarding exemplary ECDs are provided below with reference toFIGS. 2A and 2B. It will be understood, however, that ECD70is provided as a non-limiting example and that, in other embodiments, the ECD may include other components in addition to or in lieu of TWC71and/or GPF72, including but not limited to a lean NOx trap, an SCR catalyst, a diesel or gasoline particulate filter, an oxidation catalyst, or an alternative gas treatment device. For example, in some embodiments, an alternate catalyst or exhaust after treatment device may be positioned upstream of the GPF72, in place of the TWC71.

Controller12is shown inFIG. 1as a microcomputer, including microprocessor102, input/output ports104, an electronic storage medium (e.g., computer-readable) for executable programs and calibration values shown as read-only memory106in this particular example, random access memory108, keep alive memory110, and a data bus. Controller12may receive various signals from sensors coupled to engine10, in addition to those signals previously discussed, including measurement of inducted mass airflow (MAF) from mass airflow sensor120; engine coolant temperature (ECT) from temperature sensor112coupled to cooling sleeve114; a profile ignition pickup signal (PIP) from Hall effect sensor118(or other type) coupled to crankshaft40; throttle position (TP), or throttle opening, from a throttle position sensor; and absolute manifold pressure signal, MAP, from pressure sensor122. Engine speed signal, RPM, may be generated by controller12from signal PIP. Manifold pressure signal MAP from a manifold pressure sensor may be used to provide an indication of vacuum, or pressure, in the intake manifold. Note that various combinations of the above sensors may be used, such as a MAF sensor without a MAP sensor, or vice versa. During stoichiometric operation, the MAP sensor can give an indication of engine torque. Further, this sensor, along with the detected engine speed, can provide an estimate of charge (including air) inducted into the cylinder. In one example, sensor118, which is also used as an engine speed sensor, may produce a predetermined number of equally spaced pulses every revolution of the crankshaft. The controller12receives signals from the various sensors ofFIG. 1(e.g., pressure sensor15, temperature sensor112, pedal position sensor134, etc.) and employs the various actuators (e.g., a valve actuator of a valve in a bypass passage of the GPF72, as shown inFIGS. 2A-2B, throttle plate64, spark plug92, wastegate valve actuator163, etc.) ofFIG. 1to adjust engine operation based on the received signals and instructions stored on a memory of the controller. For example, adjusting a percentage of exhaust gasses flowing through GPF72(as described further below with reference toFIG. 4) may include sending a signal from the controller to an actuator of a valve (such as valve224shown inFIGS. 2A-2B) within ECD70to regulate valve positioning, thereby adjusting the percentage of exhaust gasses flowing through GPF72.

Storage medium read-only memory106can be programmed with computer readable data representing instructions executable by microprocessor102for performing the methods described herein, as well as other variants that are anticipated but not specifically listed. As described above,FIG. 1shows only one cylinder of a multi-cylinder engine, and each cylinder may similarly include its own set of intake/exhaust valves, fuel injector, spark plug, etc.

FIGS. 2A-2B and 3show a portion of an exhaust passage in a vehicle exhaust system (such as exhaust passage48inFIG. 1) including an emission control device (ECD)200. In some examples, ECD200may be ECD70ofFIG. 1.FIGS. 2A-2Bshow a side view of the ECD200where the ECD200includes a central axis248running through a center of the ECD200.FIG. 3shows a cross section of the ECD200which is arranged such that a vertical axis304is perpendicular to the central axis248seen in each ofFIGS. 2A and 2B. The cross section ofFIG. 3is taken downstream of a TWC housing204ofFIGS. 2A and 2B, and upstream of a valve224ofFIGS. 2A-2B, as shown by cross section A-A ofFIGS. 2A-2B.

As shown inFIGS. 2A-2B, ECD200includes a TWC216, a GPF244, and the operable valve224located along a central bypass passage218(residing along the central axis248of an exhaust passage202and GPF244), and one or more peripheral passages230. Central bypass passage218and peripheral passages230connect a TWC housing204of the TWC216to a GPF housing232of the GPF244.

The TWC216is arranged in the exhaust passage202, upstream of the GPF244. Furthermore, the TWC216is arranged within the TWC housing204, the TWC housing204comprising a diverging cone206upstream of and coupled to a central portion208, which is upstream of and coupled to a converging cone210of the TWC housing204. The central portion208of TWC housing204has an inner circumferential face in face sharing contact with the outer circumferential face of the TWC216, such that the central portion208is formed around and encloses elements of the TWC. As used herein, a diverging cone has angled sidewalls that angle outward from a narrower, upstream region, to a wider, downstream region of the diverging cone. Conversely, a converging cone has angled sidewalls that angle inward from a wider, upstream region, to a narrower, downstream region of the converging cone. Moving downstream, the converging cone210forms a portion of the exhaust passage and includes a wider, first portion212(i.e., first end) and a narrower, second portion214(i.e., second end), where the first end is coupled to an upstream portion of the exhaust passage and the second end is coupled directly to an entrance to a first portion220of the central bypass passage218. Said another way, the converging cone210includes a wall that angles inward from the first portion212(i.e., first end) to the second portion214(i.e., second end downstream of the first end), where it is coupled to the first portion220of the central bypass passage218(located downstream of the first end).

The central bypass passage218includes the first portion220disposed upstream of the GPF244and a second portion222passing through a center of the GPF244, centered along the central axis248. More specifically, the central bypass passage218includes the first portion220disposed upstream of the GPF244, and the second portion222passing through a center aperture of the GPF244formed around the central axis248. The first portion220of the central bypass passage218includes a valve224disposed within it. Valve224may be referred to herein as a bypass valve and is adjustable via a controller (such as controller12shown inFIG. 1) into a plurality of positions (e.g., a plurality of positions between fully open and fully closed and including the fully open and fully closed positions). In this way, the valve224may be actively controlled based on engine operating conditions, as discussed further below with reference toFIGS. 4-5.

The valve224includes a valve plate226and a valve actuator228, where at least a portion of the valve actuator228is disposed external to an interior of the first portion220of the central bypass passage218and the valve plate226is positioned within the interior of the first portion220of the central bypass passage218. Furthermore, the portion of the valve actuator228that is disposed external to the interior of the first portion of the central bypass passage218is positioned within a space formed between an outer wall of the central bypass passage218and an outer wall of the one or more peripheral passage230(i.e., outer passages). The position of the valve224may be adjusted by a controller (such as controller12ofFIG. 1) having computer readable instructions stored in a memory of the controller for actuating such an adjustment. The controller may signal the actuator228of the valve224to actuate the valve into a first position (i.e., fully closed position), as seen inFIG. 2A, such that the valve plate226of the valve224blocks exhaust gas from flowing through the central bypass passage218. Alternatively, the controller may signal (e.g., send a signal to) the actuator228of the valve224to actuate the valve into a second position (i.e., fully open position), as seen inFIG. 2B, such that the valve plate226of the valve224is open to exhaust gas flowing through the central bypass passage218. As one example, the actuator228may include a motor or hydraulic actuator that moves (e.g., rotates) the valve plate226of valve224into different positions within the interior of the central bypass passage218. Due to its external location, the actuator213may be accessible for maintenance, repair, and/or replacement. Further details regarding valve224position, exhaust flow, and engine operating conditions that lead to a change in the position of the valve224may be found further below.

Returning toFIGS. 2A and 2B, in addition to the converging cone210of the TWC housing204being coupled to the central bypass passage218, the converging cone210of the TWC housing is also coupled to one or more peripheral passages230(i.e., outer passages). The peripheral passages230are coupled between the converging cone210and the GPF244, and are spaced away from the central bypass passage218. More specifically, the plurality of peripheral passages230are positioned between the converging cone210and a diverging cone234of the GPF housing232. For example, each of the peripheral passages230are coupled between the first portion212of the converging cone210and a second portion238of the diverging cone234. The one or more peripheral passages230are spaced circumferentially around an exterior of the central bypass passage218, but within an outer diameter of one of the exhaust passage upstream of the converging cone210or a central portion240of the GPF housing232. In this way, the peripheral passages230may be contained within a packaging space defined by the exhaust passage, GPF housing232, and/or TWC housing204. At least one of the one or more peripheral passages230are equipped with a pressure sensor231(which may be similar to pressure sensor15shown inFIG. 1), where a portion of the pressure sensor231may be disposed external to an interior of the peripheral passage230and a portion of the pressure sensor231may be positioned within the interior of the peripheral passage230for measuring a pressure of exhaust gas flowing through the peripheral passage230. Thus, the pressure sensor may be in communication with the controller. In alternate embodiments, the pressure sensor231may be coupled to one of the converging cone210or diverging cone234such that the pressure sensor is disposed upstream of the GPF244. Peripheral passages230allow different percentages of exhaust gasses to pass from the TWC housing204to the GPF housing232, depending on position of the valve224, as discussed further below.

As mentioned above, peripheral passages230are coupled to the downstream GPF housing232. For example, an upstream, first end of the peripheral passages230is coupled to the converging cone210and a downstream, second end of the peripheral passages230is coupled to the diverging cone234of the GPF housing232. GPF housing232comprises the diverging cone234upstream of and coupled to a central portion240of the GPF housing232, which is upstream of and coupled to a second converging cone242of the GPF housing232. The diverging cone234, forming a portion of the housing of the GPF, is arranged upstream of the GPF244and downstream of an entrance to the first portion220of the central bypass passage218. The diverging cone234includes a narrower, first portion236(i.e., first end) coupled to an outer wall of the first portion220of the central bypass passage218and a wider, second portion238(i.e., second end) coupled to the central portion240of the housing of the GPF (i.e., GPF housing232) that surround the GPF244. The central portion240of the housing of the GPF (i.e., GPF housing232) is formed around and encloses filter elements of the GPF244, and is coupled between the diverging cone234and second converging cone242, wherein the second converging cone is arranged downstream of the GPF244. The GPF244, arranged in the exhaust passage202and having the central axis248, is arranged circumferentially around an outer perimeter of the central bypass passage218, specifically, the second portion222of the central bypass passage218.

Having disclosed the structural elements of ECD200inFIGS. 2A and 2B, the path that an exhaust flow246may take in ECD200, depending on position of the valve224, may be discussed further. The position of the valve224may be changed or maintained depending on engine operating conditions in order to adjust the percentage of exhaust flow246flowing through the peripheral passages230and through the GPF244. Specifically,FIG. 2Ashows the exhaust flow246through the ECD200when the valve224is in the first position (e.g., closed position), thereby blocking exhaust gases from flowing through the central bypass passage218.FIG. 2Bshows the exhaust flow246through the ECD200when the valve224is in the second position (e.g., open position), thereby allowing exhaust gases to flow through the central bypass passage218. As introduced above, the exhaust flow246through the ECD200may comprise exhaust gases flowing through the exhaust passage in which the ECD200is installed, from one or more engine cylinders.

Looking atFIG. 2A, exhaust flow246first enters ECD200through the exhaust passage202and subsequently enters the diverging cone206of the TWC housing204. All exhaust flow246then passes through TWC216, and into converging cone210. The angled, narrowing shape of the converging cone210(as previously discussed) directs exhaust gasses to the first portion220of the central bypass passage218. Owing to the valve224being in a fully closed (i.e., first) position, no exhaust flow may continue downstream in the first portion220of the central bypass passage218, and is thus directed back towards the upstream converging cone210. All of the exhaust flow246is thus directed to travel through one or more peripheral passages230, coupled to the wider portion of the converging cone210, and eventually downstream to the diverging cone234of GPF housing232. Alternatively, some of the exhaust flow246may initially travel through peripheral passages230after exiting the TWC216, without first being directed to the first portion220of the central bypass passage218. All of the exhaust flow246then passes through the elements (e.g., filtering elements) of GPF244, and into the downstream second converging cone242of the GPF housing232. Thus, all the exhaust flow246is filtered by the GPF244when the valve224is fully closed. The exhaust flow246may then continue through the most downstream portion of ECD200, exhaust passage202, where it then exits ECD200. Some examples for when the valve224may be in a first position includes one or more of a cold start condition including an engine temperature being below a threshold temperature, an active regeneration event of the GPF, and vehicle acceleration over a threshold level (discussed in greater detail below with reference toFIGS. 4 and 5).

Turning now toFIG. 2B, exhaust flow246travels the same initial steps as inFIG. 2A. Exhaust flow246first enters ECD200through the exhaust passage202and subsequently enters the diverging cone206of the TWC housing204. All exhaust flow246then passes through TWC216, and into converging cone210. The angled, converging inner surface of the converging cone210(previously discussed) directs a larger percentage of exhaust flow246into the first portion220of the central bypass passage218than the peripheral passages230, with the remaining percentage of exhaust flow246traveling through the one or more peripheral passages230. Owing to the valve being in a second position (i.e., fully open), exhaust flow246may continue downstream within the central bypass passage218to the second portion222of the central bypass passage218. The second portion222of the central bypass passage bypasses the GPF (as previously discussed) allowing exhaust flow246to travel through the central portion240of the GPF housing232without passing through the elements, or coming into contact with, the internal elements of the GPF244. Once exhaust flow246exits the second portion222of central bypass passage218, it enters the diverging cone234of the GPF housing232and travels to the most downstream portion of ECD200, the exhaust passage202, where it exits the apparatus. Some examples for when the valve224may be in a second position includes one or more of a cold start condition when the engine temperature is at or above a threshold temperature, or when vehicle acceleration is not over the threshold level, and the active regeneration event of the GPF is not occurring (discussed in greater detail inFIGS. 4 and 5). In this way, when the valve224is in the second position, a larger, first portion of exhaust gas travels through the central bypass passage218, thereby bypassing the GPF, while a smaller, remaining second portion of exhaust gas travels through the peripheral passages230and through the GPF244(e.g., to be filtered by the GPF).

FIGS. 2A and 2Bdepict a first and second position of the valve, respectively; however, the valve may be in a third position (i.e., intermediate position), where the third position is between the first and second position. The controller may signal the actuator228to adjust the position of the valve plate226of valve224to increase an amount of opening of the valve224, in order to decrease the percentage of exhaust gas flowing through the peripheral passages230and subsequently through the GPF244. Alternatively, the controller may signal the actuator228to adjust the position of the valve plate226of valve224to decrease the amount of opening of the valve in order to increase the percentage of exhaust gas flowing through the peripheral passages230and subsequently through GPF244.

It will be appreciated thatFIG. 2AandFIG. 2Brepresent only one configuration for ECD200. Alternative embodiments may contain various numbers of peripheral flow passages, may employ various types of actuators, may use a catalyst or alternative gas treatment device other than a TWC, and/or may use more than one unitary bodied GPF (that is, multiple, smaller GPFs may be used while still maintaining an innermost central GPF bypass passage and an outermost face sharing contact with GPF housing). The passages described inFIG. 2AandFIG. 2B(i.e., exhaust passages202, peripheral flow passage(s)230, and the central bypass passage218) may be annular in shape, or assume a plurality of geometric variants (such as square, hexagonal, etc.) so long as they maintain the ability to allow exhaust gas to flow through their hollow bodies. Furthermore, the shape of the TWC and GPF housings may have a central portion that is circular, square, rectangular, hexagonal, etc. and may be identical to or different than one another (i.e., the central portion of GPF housing may assume a geometric configuration that is the same as, or different to, the geometric configuration of the central portion of the TWC housing). Furthermore, ECD system200may have one or more sensors located within the system that may be responsible for monitoring temperature or percentage of exhaust gasses passing through at least one of the central bypass passage218and peripheral passage(s)230. Said sensors may communicate any data gathered to the controller of the vehicle (such as controller12seen inFIG. 1), which may respond by signaling an actuator (such as actuator213ofFIGS. 2A and 2B) to actuate a valve (such as valve224ofFIGS. 2A and 2B) to change position in response to vehicle operating conditions.

Turning now toFIG. 3, a cross section of the ECD200is shown. As introduced above, the cross section of the ECD200is arranged such that a vertical axis304is perpendicular to the central axis248seen in each ofFIGS. 2A and 2B. Additionally, the cross section is taken at section A-A shown inFIG. 2B, downstream of the TWC housing204, and upstream of the valve224. In this embodiment, four peripheral (i.e., outer) passages230, and one central bypass passage218are shown, whereby exhaust gas may flow from the TWC housing204to the GPF housing232. As shown inFIG. 3, the four peripheral passages230surround an outer diameter of the central bypass passage218. Within the central bypass passage218, the valve224is seen. As introduced above with reference toFIGS. 2A-b, valve224is comprised of the valve plate226and the actuator228. Valve plate226is housed within the diameter of the central bypass passage218and may be operably controlled by actuator228. Further, each outer surface of each peripheral passages230is spaced away from an outer surface of the central bypass passage218such that space is formed around the central bypass passage218. As shown inFIG. 3, the four peripheral passages230are spaced circumferentially around the central bypass passage218. In alternate embodiments, the ECD200may include a different number of peripheral flow passages than four. For example, the ECD200may include one, two, three, or five peripheral flow passages spaced circumferentially around the central bypass passage218, but spaced away from the central bypass passage218.

It will be appreciated that central bypass passage218and peripheral passages230are contained within a space defined by an outer diameter302of a central portion240of the GPF housing. Said another way, all of the peripheral passages230are positioned interior to the outer diameter302of the central portion240of the GPF housing in a radial direction (or a direction perpendicular to the central axis of the ECD200). Containing all passages within a space defined by the outer diameter302of the central portion240of the GPF housing (yet spacing the peripheral passages230away from the central bypass passage218) allows the ECD to be compact, while still allowing access to the central valve224. Said yet another way, the vertical distance (as defined by vertical axis304) and horizontal distance (as defined by a horizontal axis306) from the central axis (at a center of the valve224, such as central axis248ofFIGS. 2Aand2B) to each passage is smaller than the diameter of the central portion240of the GPF housing. It will be appreciated that the central portions of the GPF housing and TWC housing define the diameter of the housings, and so the terms “diameter of the central portion of the GPF housing” and “diameter of the central portion of the TWC housing” may be interchangeable with “diameter of the GPF housing” or “GPF housing diameter” and “diameter of the TWC housing” or “TWC housing diameter”, respectively. As shown inFIGS. 2A-2B, the TWC housing diameter is the same as the GPF housing diameter; however, in alternative embodiments, the TWC housing diameter may be different from the GPF housing diameter. In the embodiment where the diameters of the GPF housing and TWC housing are different, the peripheral passages230may fit within a space defined by a largest of the TWC housing diameter and the GPF housing diameter (such that the peripheral passages230do not extend outside of the outer diameter of the GPF or TWC (whichever is largest). In another embodiment, the GPF housing and/or TWC housing may not have circular cross-sections (i.e., may not have an annular central portion), in which case the peripheral passages may fit within a space defined by a height and width (or cross-section) of a housing of the TWC and/or GPF. For example, the GPF and TWC housings may have a hexagonal central portion of identical dimensions (while still maintain a diverging cone upstream of the central portion and converging cone downstream of the central portion), in which case all passages (i.e., peripheral flow passages and the central bypass passage) would be spaced within the cross-section of the hexagonal central portion of the GPF and TWC housings.

The amount of exhaust flow (e.g., percentage of exhaust flow of the total exhaust flow passing through an exhaust passage and entering the ECD200) passing through peripheral passages230is dependent upon the position of the valve224. When valve224is in the aforementioned first position (not shown inFIG. 3), the central bypass passage218is be closed to exhaust gasses, leading to approximately 100% of the exhaust gases flowing through the peripheral passages230(as schematically depicted inFIG. 2A). When the valve224is in the aforementioned second position, as seen inFIG. 3(also seen inFIG. 2B), the central bypass passage218is open so that exhaust gasses travel down the central bypass passage218(and past the GPF), and a lower percentage of exhaust gasses will pass through peripheral passages230GPF housing232and through the GPF244. The valve224may also assume a plurality of intermediate positions between fully closed to exhaust gasses (i.e., first position) and fully open to exhaust gasses (i.e., second position). Intermediate valve positions of valve224may affect the percentage of gasses flowing through peripheral passages230and central bypass passage218, such that as valve224moves from the second position to the first position (i.e., closed to open) a larger percentage of exhaust gasses will pass through the central bypass passage218and a lower percentage of exhaust gasses will pass through the peripheral passages230.

While central bypass passage218, peripheral passages230, and GPF housing232are all depicted as annular in shape, alternative embodiments may employ a plurality of geometric configurations. For example, passages may be square, rectangle, hexagonal, etc. Additionally, alternative embodiments may call for varying numbers of peripheral passages230(i.e., one or more peripheral flow passages). While valve224is shown inFIG. 3as having an axis perpendicular to the vertical axis304, alternative embodiments may have the valve224axis arranged at angles less or greater than ninety-degrees to the vertical axis304. Furthermore,FIGS. 1-3show example configurations with relative positioning of the various components. If shown directly contacting each other, or directly coupled, then such elements may be referred to as directly contacting or directly coupled, respectively, at least in one example. Similarly, elements shown contiguous or adjacent to one another may be contiguous or adjacent to each other, respectively, at least in one example. As an example, components laying in face-sharing contact with each other may be referred to as in face-sharing contact. As another example, elements positioned apart from each other with only a space there-between and no other components may be referred to as such, in at least one example.

Turning toFIG. 4, a method for adjusting a valve positioned in a bypass passage disposed through a center of a GPF to vary a percentage of exhaust gas passing through the GPF is shown. As introduced above, an emission control device (such as ECD200shown inFIGS. 2A-2B and 3) may include an upstream after treatment device (such as TWC216shown inFIGS. 2A-2B) and a GPF (such as GPF244shown inFIGS. 2A-2B and 3) and a central bypass passage (such as central bypass passage218shown inFIGS. 2A-2B and 3) passing through a center of the GPF which allows exhaust gas to pass through the passage and not through pores (or filtering elements) of the GPF. The central bypass passage includes a valve (such as valve224shown inFIGS. 2A-2B and 3) disposed therein, upstream of a portion of the passage passing through the center of the GPF. The valve is adjustable into a plurality of positions to adjust a percentage of exhaust gas flowing through the central bypass passage and/or through the GPF. Instructions for carrying out method400and the rest of the methods included herein may be executed by a controller (such as controller12shown inFIG. 1) based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system, such as the sensors described above with reference toFIG. 1. The controller may employ engine actuators of the engine system to adjust engine operation, according to the methods described below. Furthermore, inFIGS. 4 and 5, described below, the valve in the central bypass passage of the GPF may be in a first position, a second position, or an intermediate position lying between the two positions. Additionally, inFIGS. 4 and 5, described below, the valve in the central bypass passage of the GPF may be referred to simply as the “valve”. The reader may assume that all valve references inFIGS. 4 and 5are referring to the valve in the central bypass passage of the GPF (such as valve224ofFIGS. 2A, 2B, 3), unless otherwise stated. As used herein, when the valve is in a “first position”, the valve may be referred to as “closed” (e.g., closed such that exhaust gasses do not flow past the valve and through the central bypass passage), whereby exhaust gasses cannot flow through the central bypass passage, and in response, all exhaust gasses flow through peripheral flow passages surrounding the central bypass passage and connecting the upstream catalyst (e.g., TWC) to the GPF. Additionally, as used herein, when the valve is in a “second position”, the valve may be referred to as “open”, whereby exhaust gasses can flow through the central bypass passage, and in response, a percentage of exhaust gasses flow through the central bypass passage, while the remaining percentage of exhaust gasses flow through the peripheral flow passages. Furthermore, it will be appreciated that any references to the valve being actuated upon, or a change in valve position (e.g., first, second, open, closed, intermediate, etc.), will imply that the controller is employing an actuator of the valve (which may be at least partially external to the central bypass passage) to move a position of a valve plate of the valve (the valve plate positioned across an interior of the central bypass passage) into the desired position and thus change the amount of exhaust flow passing through the central bypass passage.

FIG. 4begins at402, where engine operating conditions are estimated and/or measured. Establishing and/or measuring engine operating conditions may include processing incoming data from sensors within and/or outside of the ECD, determining if the vehicle has just turned on (i.e., cold start), if the vehicle is in cruise control, if the vehicle is accelerating/decelerating, etc. For example, engine operating conditions may include engine speed and/or load, exhaust oxygen content, ambient temperature, engine temperatures, a pressure upstream of the GPF, a percentage of exhaust flowing through the GPF, a temperature of the ECD, an exhaust oxygen content of the ECD, etc.

At404the method includes determining if the engine is operating under cold start conditions. Cold start conditions may include starting the engine when a temperature of the engine (and/or an ambient temperature) is below a threshold temperature. The threshold temperature may be based on a nominal operating temperature for the engine where fluids of the engine are heated up to a threshold level. During the cold start phase (e.g., when the engine temperature, or engine coolant temperature, is less than the threshold temperature) the engine may produce soot due to the controller employing a warm-up strategy to heat the catalyst in the exhaust passage (e.g., the TWC) as fast as possible. One aspect of this warm-up strategy may include late fuel injection, where the controller actuates the fuel injectors to retard fuel injection timing to the engine cylinders. Other aspects of the warm-up strategy may include adjustments of spark timing, idle speed, air-to-fuel ratio, and turbocharger operation. At cold-start, these and possibly other aspects of engine operation, are optimized for fast catalyst (e.g., TWC) warm-up, and thus are not optimized for minimal particle emissions. If the controller determines that the engine is operating under cold start conditions then the method progresses to406.

At406the method includes closing the valve of the central bypass passage of the GPF or maintaining the valve in the closed position (e.g., if it is already closed). As a result, all or most of the exhaust gas from the engine cylinders is directed through the peripheral flow passages and through the GPF. Thus, the GPF may filter the soot particulate matter out of the exhaust gas before the exhaust gas is expelled from the engine. In response to cold start conditions, the controller may signal an actuator of the valve in the central bypass passage to actuate the valve into the closed position such that the valve plate of the valve blocks exhaust gas from flowing through the bypass passage. Alternatively, if the valve of the central bypass passage is already fully closed, the controller may not send a signal to the valve actuator in order to maintain the valve in the close position. In alternative embodiments, the valve may be actuated to move to a partially closed position, as opposed to entirely closed, so long as the ECD continues to operate to remove a desired amount of soot from the exhaust gas as dictated by emission standards (i.e., valve may be 10% open to suit engine operating conditions, while still meeting emission standards). Having closed or maintained a closed valve in the central bypass passage of the ECD, the method progresses to408.

At408, the method includes the controller assessing if the engine warm-up period (i.e., cold start conditions or warm-up strategy) is complete. If the controller determines that the engine is still acting under warm up conditions, then the method progresses to410. As one example, the controller may determine that the engine warm-up period is not complete if the engine temperature is still below the threshold temperature. As another example, the controller may determine that the engine warm-up period is not complete if fuel injection is still late (e.g., retarded) relative to a threshold or standard fuel injection timing during engine running conditions. As yet another example, the controller may determine that the warm-up period is not compete if a threshold amount of time (e.g., for engine warm-up) has not expired.

At410, the method includes maintaining the valve in the central bypass passage closed. Maintaining the valve closed may not require any action from the actuator controlling the valve of the central bypass passage. After410occurs the method returns to408. The method may cycle between408and410until the controller determines that engine warm up is complete and the method continues to412.

At412, the method includes opening the valve in the central bypass passage in response to the engine warm-up period being complete following the cold start. Having completed warm-up conditions, and so long as no other engine operations are occurring that produce soot above a threshold level (e.g., where the threshold level is based on an emission standard), the controller may signal the actuator of the valve in the central bypass passage of the GPF to actuate the valve to change position from closed to open. Changing position of the valve from closed to open allows exhaust gasses to pass through the central bypass passage, bypassing the GPF in the process. In one example, the method at412may include fully opening the valve in the central bypass passage. As another example, the method at412may include increasing the opening of the valve so that it is partially open. In some examples, the opening of the valve may increase as the engine warms up (e.g., as the engine temperature increase or as fuel injection returns from the retarded state to the baseline, non-retarded state). Once the valve is successfully opened (either fully opened or partially opened, depending on engine operating conditions), method400continues to424(as discussed further below).

Returning to404, if the controller determined that the engine is not operating under cold start conditions, then the method proceeds to414. At414, the method includes determining if active GPF regeneration conditions are met. Active GPF regeneration conditions may include a buildup of particulate matter (i.e., soot and/or ash) above a threshold in the GPF such that a pressure drop across the GPF is greater than a threshold level. As one example, the threshold level may be based on a level that results in increased backpressure on the engine cylinders that causes a threshold percentage decrease in engine torque output. Furthermore, the controller may be programmed to detect a specific operating condition, such as steady highway cruise, before determining regeneration conditions are being met. If the controller determines that active GPF regenerations conditions are met at414, then the method proceeds to416. At416, the method includes closing the valve in the central bypass passage and regenerating the GPF. Closing the valve occurs as mentioned before, via an actuator coupled with the valve responding to signals from the controller. The details of regeneration of the GPF and valve operation during regeneration are discussed in greater detail below with reference toFIG. 5. Having completed regeneration, and if no other engine operating conditions are detected that require a change in valve position, the method400will come to an end.

Returning to414, if active GPF regeneration conditions are not met, then the method proceeds to418. At418, the method includes determining if the vehicle is accelerating. Acceleration may be detected based on an increase in opening of the throttle, an increased rate of fuel injection, and/or an increase in pedal position above a threshold. Strong acceleration (e.g., a tip-in or pedal position increase over a threshold) may lead to an increase in engine soot output. Thus, in response to engine acceleration (or an acceleration over a threshold), the controller may actuate the valve to fully close or partially close (via sending a signal to the actuator coupled to the valve) if the valve is not already closed by a desired amount. A threshold for acceleration may be used to determine when soot is being produced at a level warranting the controller to actuate a change in valve position in order to meet emission standards. If the vehicle is accelerating, or accelerating above a predetermined threshold, then the method proceeds to420.

At420, the method includes closing (or partially closing) the valve in the central bypass passage. As discussed in418, in response to vehicle acceleration, or acceleration above a predetermined threshold that is known to cause soot above a threshold level, the controller may signal the valve actuator to change the valve position to a fully closed or partially closed position (e.g., the controller may decrease the amount of opening of the valve). Determining whether to partially or fully close the valve may be dependent on a number of operating conditions, such as, determining how closed the valve must be in order to reduce soot in the exhaust gas by a threshold amount, a pressure in the ECU, percentages of exhaust gas moving through the central bypass passage and peripheral flow passages, a temperature of the exhaust gas, an air to fuel ratio, etc. If the actuator fully closes the valve (i.e., moves valve to the first position) then all of the exhaust gasses will pass through peripheral flow passages (such as peripheral passages230shown inFIGS. 2A-3, downstream to the GPF, where the increased soot output from acceleration may be better captured in the filter. If the actuator partially closes the valve (i.e., an intermediate position between the first and second positions) then an increased percentage of exhaust gasses will pass through peripheral flow passages, while the remaining percentage will continue to flow through the now partially obfuscated central bypass passage. Having closed, or partially closed, the valve controlling access to the central bypass passage, method400continues to424(as discussed further below). It will be appreciated that in an alternative embodiment, the soot generated by increased acceleration (or acceleration above a predetermined threshold), may be dealt with by engine calibration, thereby negating the need for the controller to close the valve in order to meet soot thresholds. In such an alternative embodiment, the method would not continue to420, but to422instead.

Returning to418, if the vehicle is not accelerating, or not accelerating at or above a predetermined threshold to trigger closing of the valve as described above, then the method continues to422. At422, the method includes maintaining the open (or partially open) position of the valve in the central bypass passage. Maintaining the open valve (i.e., in the second position) may require no signal from the controller to the actuator of the valve. It will be appreciated that other operating conditions may be concurrently occurring so as to require the valve to be partially open instead of fully open, despite no acceleration detected to warrant closing of the valve in aforementioned418. Furthermore, some operating conditions may be concurrently occurring that lead the controller to fully close the valve position despite no acceleration detected to warrant closing of the valve in aforementioned418. For example, at422the controller may detect a pressure signal that triggers the controller to regenerate the GPF. Under these conditions, the controller may determine that regeneration is more crucial to engine operation than maintaining an open valve, and in response, the controller may signal the actuator to close the valve so that regeneration may occur, despite no acceleration detected to warrant closing of the valve in aforementioned418. It will be appreciated that despite being schematically depicted as a strict sequential process, that the controller may be simultaneously tracking all vehicle operations (e.g., determining cold start conditions, regeneration conditions, acceleration conditions, etc.) and continually ranking the priority of said conditions in order to determine optimal valve position.

At424, the method includes adjusting engine operation based on a change in the pressure across the GPF due to adjusting the position of the valve. For example, following adjusting the valve during the methods described above, the controller may determine the pressure across the GPF by taking a first pressure reading within the ECD system, upstream of the GPF but downstream of the TWC, and a second pressure downstream of the GPF. In one example, the second pressure reading may be atmospheric pressure. Thus, determining the pressure drop across the GPF may include comparing the first pressure reading to the second pressure reading, and determining if said pressure drop is influencing torque output of the engine. As another example, the controller may determine the pressure upstream of the GPF and use this pressure to estimate a backpressure on the engine and whether torque output is being decreased beyond a threshold level due to the backpressure. For example, when the valve is in the first position (closed to exhaust gasses bypassing the GPF, such as the valve position shown inFIG. 2A) then all exhaust gasses entering the ECD pass through peripheral flow passages and to the downstream GPF. When this occurs, the pressure drop through the GPF causes an extra load on the engine, which may reduce engine torque output. The pressure drop may reduce torque output enough that the controller may take steps to compensate by increasing engine torque output. As such, the method at424may include adjusting the throttle opening, spark timing, or turbocharger boost (in a turbocharged engine) to increase engine torque output so that the effect of the GPF backpressure is not apparent to the driver. For example, the controller may increase the throttle opening to increase torque as the pressure drop across the GPF (or the pressure upstream of the GPF) increases. The amount of pressure drop may also be dependent on how much particulate matter has accumulated in the GPF, and/or on the percentage of gasses flowing through the GPF. For example, the valve may be fully open (i.e., second position) or partially open (i.e., in between first and second position), which allows a portion of exhaust gas to bypass the GPF, but owing to a large amount of particulate matter in the GPF, the pressure drop may be substantial enough for the controller to adjust engine operations based on change in pressure across the GPF. Having adjusted engine operations based on change in pressure across the GPF, method400comes to an end.

In this way, a vehicle controller may determine during which engine operating conditions increased soot production is likely to occur and, in response to those operating conditions, signal an actuator of a valve in a central bypass passage of a GPF to adjust the valve accordingly, wherein a closed valve blocks exhaust gas access to the central bypass passage, thereby leading all of the exhaust gas traveling through peripheral flow passages and through pores of the GPF. Comparatively, an open (or partially open) valve allows a portion of exhaust gasses to travel down the central bypass passage and through a center of the GPF without flowing through the pores of the GPF, thereby reducing the amount of exhaust gas traveling through the pores of the GPF. The controller may estimate and/or measure multiple engine operating conditions simultaneously to determine a desired valve position of the valve, which may include the first position, the second position, or an intermediate position between first and second position, as described above.

Turning toFIG. 5, a method500is shown for performing a GPF regeneration event in an emission control device including a GPF (such as the ECD200and GPF244shown inFIGS. 2A-2B and 3). It should be noted that method500is a continuation of416ofFIG. 4.

Method500begins at502by closing or partially closing the valve in the central bypass passage in response to the controller determining that active GPF regeneration conditions are met, as discussed above with reference to414ofFIG. 4. The method at502may include determining whether to partially close or fully close the valve based on engine operating conditions. For example, full closure of the valve (i.e., the first position) may cause all the heated exhaust gases to pass through pores of the GPF instead of through the central bypass passage in which the valve is installed. As a result, the temperature of the GPF may increase and more soot stored within the GPF may be burned off the filter during the regeneration event. Comparatively, partial closure of the valve (i.e., a position between first and second position) may cause less heated exhaust gases to pass through the pores of the GPF (than if the valve were fully closed) and thus the temperature of the GPF may not increase as much as if the valve were fully closed. As a result, the controller may control a temperature of the GPF during the regeneration event based on a position of the valve. There may be a threshold temperature or temperature range for maintaining the GPF temperature during regeneration. For example, during regeneration, the controller may adjust the valve to maintain the GPF above a lower threshold temperature (e.g., below which soot may not be removed from the filter) and below an upper threshold temperature (e.g., above which degradation of the GPF may occur). Further, by only partially closing the valve, engine power loss (e.g., from increased backpressure from flowing exhaust gas through the GPF) may be reduced. Once the controller has determined whether the valve should be fully or partially closed (and what percentage opening or closing it should be moved into), signaled the valve actuator, and adjusted valve position accordingly, the method proceeds to504.

At504, the method includes determining if the GPF is at a regenerative temperature. The GPF temperature may be determined based on output from an exhaust gas temperature sensor positioned proximal to the GPF (such as temperature sensor16shown inFIG. 1). The regeneration temperature may be a filter regeneration light-off temperature at which, given sufficient excess oxygen, particulate matter accumulated in the GPF may be oxidized. The temperature for regeneration may be a threshold value or a value range. If it is determined that the GPF is not at the regenerative temperature (e.g., less than), then the method proceeds to506. At506, the method includes increasing the exhaust gas temperature in an effort to bring the GPF to the regeneration temperature. The exhaust gas temperature may also be controlled to achieve a desired rate of particulate matter oxidation. Increasing exhaust gas temperature will cause the temperature of the GPF to increase as well. Increasing the exhaust gas temperature at506may include one or more of retarding spark timing, increasing throttle opening (e.g., opening of throttle62ofFIG. 1), increasing engine speed, increasing engine load, etc. Method500will continue to cycle between506and504, until the controller determines (at504) that the GPF is at suitable temperatures for regeneration. If it is determined that the GPF is at (e.g., greater than or equal to) the regeneration temperature, method500proceeds to508.

At508, the method includes initiating active regeneration of the GPF. Initiation of active GPF regeneration may include initiating deceleration fuel shut-off (DFSO) to provide oxygen for particulate matter (e.g., soot) oxidation. In some examples, DFSO may be initiated only under select conditions; for example, DFSO may be initiated if engine speed and/or load are below respective thresholds, and/or if other inputs (e.g., accelerator pedal position) do not indicate an imminent driver tip-in or request for torque. By initiating DFSO, sufficient levels of excess oxygen may be supplied to the GPF that, in combination with sufficient temperatures, facilitate oxidation of accumulated particulate matter and at least partial regeneration of the GPF. Thus, the GPF may be actively regenerated via excess oxygen received from the engine. Other approaches may be employed to increase excess oxygen at the GPF, alternatively or in addition to DFSO. For example, one or more of throttle opening, air-fuel ratio (e.g., enleanment), and variable cam timing may be adjusted to increase the supply of excess oxygen. Once the controller has initiated active regeneration, the method continues to510.

At510, the method includes adjusting the valve in the central bypass passage and a combustion air-to-fuel ratio (A/F) of the engine to maintain the GPF at the regeneration temperature. During regeneration, soot oxidation (i.e., soot combustion) is exothermic. If regeneration is uncontrolled it may increase the temperature in the ECD enough to damage the GPF. The reaction may be controlled using valve control and/or air-to-fuel ratio control. For example, lower exhaust gas flow through the GPF with a higher air-fuel ratio may produce higher temperatures at the GPF, since the high oxygen content promotes fast oxidation, and there is little exhaust gas flowing through the GPF to carry away the heat (owing to an open or partially open valve, which directs a percentage of exhaust gasses through the central bypass passage, leaving a smaller percentage of exhaust gasses to pass through the GPF). Comparatively, higher exhaust gas flow through the GPF (occurring when the valve in the central bypass passage is fully closed or partially closed, which prevents all or most of the exhaust gas from passing through the central bypass passage, respectively) with low air-fuel ratio may cool the GPF, since the exhaust is low in oxygen, and the high exhaust gas flow through the GPF can more quickly carry away whatever heat is produced. Thus, the controller may adjust valve position (via sending a signal to the actuator coupled with the valve plate) and adjust the combustion air-to-fuel ratio (via sending a signal to one or more fuel injectors and/or the throttle valve) to increase or decrease the heat within the ECD system so that temperatures do not fall below those consistent with active regeneration, and do not surge above those that would degrade the GPF (or any other component of the ECD system). For example, the method at510may include increasing the air-to-fuel ratio combusted at the engine cylinders while increasing an opening of the valve in the central bypass passage in order to increase the temperature of the GPF if the regeneration temperature is lower than a threshold. As another example, the method at510may include decreasing the air-to-fuel ratio combusted at the engine cylinders while decreasing an opening of the valve in the central bypass passage in order to decrease the temperature of the GPF if the regeneration temperature reaches a threshold that reduces component durability (e.g., a temperature that may degrade the GPF). In another embodiment, the method at510may additionally or alternatively include enriching the exhaust gas by increasing a fuel injection amount to decrease the GPF temperature, since rich exhaust gas tends to be cooler than lean exhaust gas. In this way, the method at510may including adjusting both the valve in the central bypass passage and the combustion air-fuel ratio to maintain the GPF temperature within a desired regeneration temperature range during the regeneration event.

At512, the method includes determining if regeneration is complete. Determining if regeneration is complete may be based on one or more of the temperature of the GPF indicating that an exothermic reaction (i.e., regeneration) is no longer taking place (e.g., the temperature drops below a threshold) or pressure drop across the GPF. For example, after combusting much of the soot in the GPF during the regeneration process, exhaust gas entering the GPF will be met with less resistance passing through the GPF and the pressure drop will be reduced (compared to before the regeneration event). In this example, the controller may determine that regeneration is complete if the pressure drop across the GPF has reduced below a threshold level. As another example, the threshold level may be a level smaller than the pressure drop across the GPF prior to initiating regeneration. As yet another example, the threshold level may be a set level indicating that a certain percentage of particulate matter (e.g., soot) has been removed from the GPF.

Thus, there may be a threshold pressure drop that signifies that regeneration is complete. If regeneration is not complete, the method continues to514. At514, the method includes continuing active regeneration. For example, regeneration may continue by adjusting one or more of the valve in the central bypass passage, the combustion air-to-fuel ratio, the throttle, and/or engine fueling to maintain the regeneration temperature range and continue providing oxygen for regeneration, as described above at508and510. Until the controller has determined that regeneration is complete at512, the methodology will cycle between512and514. Once the controller has determined that regeneration is complete at512, the method continues to516.

At516, the method includes the controller returning engine actuators to their demanded state and re-opening or increasing the opening of the central bypass valve. The demanded state of vehicle actuators may be determined by the driver (i.e., driver initiated acceleration/deceleration), driving conditions (for example, wet roads may cause a vehicle to initiate four wheel drive), and engine operating conditions (e.g., acceleration, cold-start, regeneration, etc.). In the event that no other engine operating conditions require a closed valve (such as, acceleration or cold start conditions), then the controller may signal the valve actuator to adjust the valve from a fully or partial closed valve position to a partially or fully open valve position. Having adjusted valve position in response to completed regeneration, method500comes to an end. The controller may continue to monitor engine operating conditions and make additional valve position adjustments via an actuator, as disclosed inFIG. 4, method400for the duration of vehicle operation.

In this way, an emission control device may be constructed with a GPF bypass, such that the ECD (such as ECD200, seen inFIGS. 2A and 2B) does not take up more space than an exhaust system housing only a TWC and GPF (i.e., an exhaust system sans GPF bypass). Spacing between peripheral flow passages and a central bypass passage of the ECD allow for cooling of the exhaust gasses, which reduces heat of the ECD system and may extend the life of components within the system (since exposure to hot exhaust gasses without a means for cooling can present challenges to component durability). With at least a portion of the valve (e.g., a portion of the valve actuator) positioned external to the central bypass passage, in conjunction with the spacing surrounding the perimeter of the central bypass passage, the valve and/or valve actuator may be accessed more easily, thereby increasing the ease of servicing or replacing the valve. Furthermore, a shape of the converging cone portion of the TWC housing (such as TWC housing204seen inFIG. 2A) allows for an increased amount of exhaust gasses to be funneled toward the central bypass passage when the valve is open or partially open than if the TWC housing had a straight configuration that did not angle toward the central bypass passage.

The technical effect of the providing a converging cone upstream of the first portion of the central bypass passage is to direct a larger percentage of the exhaust gasses to the central bypass passage, thereby allowing a greater percentage of exhaust gas to bypass the GPF and reduce the amount of incombustible particulate matter getting trapped within pores of the GPF, when the valve is in a second (e.g., open) position. The technical effect of spacing one or more outer (e.g., peripheral) passages disposed between the converging cone and the GPF away from the central bypass passage, in addition to positioning at least a portion of the valve actuator of the valve exterior to the central bypass passage, is that the valve may be more easily accessed for repairs and servicing.

As one embodiment an apparatus for an engine emission control device comprises a gasoline particulate filter (GPF) arranged in an exhaust passage, a central bypass passage including a first portion disposed upstream of the GPF and a second portion passing through a center of the GPF, a converging cone forming a portion of the exhaust passage and arranged upstream of and connecting to the first portion, one or more outer passages coupled between the converging cone and the GPF and spaced away from the central bypass passage, and a valve arranged within the first portion. In a first example of the apparatus, the valve includes a valve plate and a valve actuator, where at least a portion of the valve actuator is disposed external to an interior of the first portion of the central bypass passage and the valve plate is positioned within the interior of the first portion of the central bypass passage. A second example of the apparatus optionally includes the first example and further includes wherein at least the portion of the valve actuator disposed external to the interior of the first portion of the central bypass passage is positioned within a space formed between an outer wall of the central bypass passage and an outer wall of the one or more outer passages. A third example of the apparatus optionally includes one or more of the first and second examples, and further includes wherein the converging cone includes a wider, first end and a narrower, second end, where the first end is coupled to an upstream portion of the exhaust passage and the second end is coupled directly to an entrance to the first portion of the central bypass passage. A fourth example of the apparatus optionally includes one or more of the first through third examples, and further includes, wherein the converging cone includes a wall that angles inward from the first end to the second end of the converging cone. A fifth example of the apparatus optionally includes one or more of the first through fourth examples, and further includes, further comprising a diverging cone forming a portion of a housing of the GPF and arranged upstream of the GPF and downstream of the first portion of the central bypass passage, wherein the diverging cone includes a narrower, first end coupled to an outer wall of the first portion of the central bypass passage and a wider, second end coupled to a central portion of the housing of the GPF that surrounds the GPF. A sixth example of the apparatus optionally includes one or more of the first through fifth examples, and further includes, wherein each of the one or more outer passages are coupled between the first end of the converging cone and the second end of the diverging cone. A seventh example of the apparatus optionally includes one or more of the first through sixth examples, and further includes, wherein the one or more outer passages includes a plurality of outer passages spaced circumferentially around an exterior of the central passage but within an outer diameter of one of the exhaust passage upstream of the converging cone or the central portion of the housing of the GPF. An eighth example of the apparatus optionally includes one or more of the first through seventh examples, and further includes, wherein the central portion of the housing of GPF is formed around and encloses filter elements of the GPF and further comprises a second converging cone positioned at a downstream end of GPF, where the central portion of the GPF housing is coupled between the diverging cone and the second converging cone. A ninth example of the apparatus optionally includes one or more of the first through eighth examples, and further includes, wherein the GPF includes a central axis and wherein the central bypass passage is centered along the central axis and wherein the GPF is formed circumferentially around an outer perimeter of the central bypass passage.

In another example, a method for an engine emission control device includes during a first condition, adjusting a valve disposed in a central bypass passage upstream of a gasoline particulate filter (GPF) of an exhaust passage, where the central bypass passage passes through a center of the GPF, into a first position to flow exhaust gas from a converging cone forming a portion of the exhaust passage upstream of the central bypass passage and through only peripheral passages surrounding the central bypass passage and connecting a housing of the GPF to the converging cone, and during a second condition, adjusting the valve into a second position to flow at least a portion of the exhaust gas from the converging cone through the central bypass passage. In the first example of the method, the method further comprises following adjusting the valve, adjusting engine operation in response to a pressure drop across the GPF. A second example of the method optionally includes the first example and further includes wherein adjusting engine operation includes adjusting one or more of turbocharger boost, spark timing, and a throttle and wherein the pressure drop is based on a pressure measured upstream of GPF in the exhaust passage. A third example of the method optionally includes one or more of the first and second examples, and further includes wherein adjusting the valve into the first position to flow exhaust gas from the converging cone and through only the peripheral passages includes flowing exhaust gas from the converging cone to an entrance of the peripheral passages coupled to a wider portion of the converging cone, flowing exhaust gas through the peripheral passages, flowing exhaust gas into a diverging cone forming an entrance to the GPF within a housing of the GPF, and flowing exhaust gas through filter elements of the GPF. A fourth example of the method optionally includes one or more of the first through third examples, and further includes wherein adjusting the valve into the second position includes flowing exhaust gas from a wider portion of the converging cone to a narrower portion of the converging cone coupled directly to an inlet to the central bypass passage to direct exhaust gas into the central bypass passage, following a converging inner surface of the converging cone, and flowing exhaust gas from the central bypass passage to a portion of the exhaust passage downstream of the GPF. A fifth example of the method optionally includes one or more of the first through fourth examples, and further includes, wherein the first condition includes one or more of a cold start condition including an engine temperature being below a threshold temperature, an active regeneration event of the GPF, and vehicle acceleration over a threshold level. A sixth example of the method optionally includes one or more of the first through fifth examples, and further includes wherein the second condition includes one or more of following the cold start condition when the engine temperature is at or above the threshold temperature or when vehicle acceleration is not over the threshold level and the active regeneration event of the GPF is not occurring. A seventh example of the method optionally includes one or more of the first through sixth examples, and further includes, wherein the first position is a fully closed position and the second position is a fully open position and further comprising adjusting the valve into a third position, where the third position is between the first position and the second position, during a third conditions, where the third condition includes during the active regeneration event of the GPF and where the third position is based on a temperature of the GPF and a desired regeneration temperature of the GPF.

In another embodiment, a system for an engine emission control device comprises a gasoline particulate filter (GPF) arranged in an exhaust passage and having a central axis, a three-way catalyst arranged in the exhaust passage upstream of the GPF, a central bypass passage including a first portion disposed upstream of the GPF and a second portion passing through a center aperture of the GPF formed around the central axis, a converging cone forming a downstream portion of a housing of the three-way catalyst and connecting to the first portion of the central bypass passage, a diverging cone forming an upstream portion of a housing of the GPF and arranged downstream of an entrance to the first portion of the central bypass passage, a plurality of peripheral passages positioned between the converging and diverging cones and spaced away from the central passage, a valve disposed within the first portion of the central bypass passage, and a controller with computer readable instructions for: adjusting a position of the valve to adjust a percentage of exhaust gas flowing through the outer passages and through the GPF and adjusting engine operation in response to adjusting the position of the valve and based on a pressure upstream of the GPF. In a first example of the system, where the valve includes a valve plate arranged within the first portion of the central bypass passage and a valve actuator, where at least a portion of the valve actuator is external to the first portion of the central bypass passage and wherein adjusting the position of the valve includes increasing an amount of opening of the valve to decrease the percentage of exhaust gas flowing through the outer passages through the GPF and decreasing the amount of opening of the valve to increase the percentage of exhaust gas flowing through the outer passages and through the GPF.