Method and system for exhaust aftertreatment device

Abstract

The present disclosure provides a method and system for an exhaust gas aftertreatment device. A method and system for an aftertreatment system arranged in an underbody of a vehicle downstream of a close-coupled aftertreatment device is provided, the aftertreatment system comprising a first aftertreatment device and a second aftertreatment device adjacent to each other. In one example, the first aftertreatment device is a hydrocarbon trap, and the second aftertreatment device is a three-way catalyst.

Description

Technical Field

[0001] The present description generally relates to methods and systems for treating combustion byproducts via one or more exhaust aftertreatment devices.

[0002] Background technology / invention content

[0003] The combustion of fuel in an engine can produce hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NO x ) of regulated emissions. NO x is a known contributor to greenhouse gases. x Efforts to reduce the generation and / or release of exhaust gas from internal combustion engine vehicles include exhaust gas recirculation (EGR), adjusting combustion parameters (eg, spark timing, air-fuel ratio, etc.), and including various catalytically active aftertreatment devices.

[0004] Although preheating (eg, igniting) the aftertreatment device may adequately treat gases such as NO during various engine operating conditions, x regulated emissions, but these devices may only function above activation and / or light-off temperatures, and such performance degrades over the life of these devices with customer driving cycles. In one example, the useful life of such devices may be 150,000 miles or some other threshold mileage. Beyond the threshold mileage, NO x Output may exceed national standards. Specifically, palladium (Pd) may sinter under high temperature and fuel-rich conditions, causing a large number of initially covered Pd atoms to agglomerate into large particles, thereby burying the Pd atoms in the cores of these large particles, where they may no longer be accessible to the gas phase. Once this occurs, the aftertreatment device requires much higher temperatures to convert the NO emitted by the engine. x emissions and other combustion byproducts, thereby extending the duration that regulated emissions escape from the tailpipe when the engine is first started (while it is at ambient temperature and experiencing an engine cold start). In other words, after a threshold number of miles, the device may require a longer duration to reach its activation temperature, which may prolong engine cold starts, thereby increasing emissions. The ability of the engine aftertreatment to treat emissions during the cold start period essentially determines the national certification tailpipe emissions standard under which the vehicle will be eligible to be sold. From model year 2015 to model year 2025, the LEV-III regulations specify that the fleet's average total HC and NOx tailpipe emissions must be reduced by 70% over the federal test procedure drive cycle.

[0005] Current solutions for storing and converting cold start HC emissions may include HC traps and passive NOx adsorbers (PNA), while current solutions for storing and converting NOx emissions may include lean NOx traps (LNT) and passive NOx adsorbers (PNA). Each of these devices has its advantages and disadvantages. Some HC trap devices may be based on a monolithic substrate that is first coated with an aluminosilicate zeolite that can store HC molecules and then coated with a three-way catalyst material that converts inlet emissions like a catalytic converter, but it also processes cold start emissions stored in the zeolite, which are then released at a higher temperature. Unfortunately, the NOx storage efficiency of conventional HC traps is not high, which prevents the use of HC traps as a comprehensive cold start emissions solution.

[0006] Similar to HC traps, PNAs are zeolite based, except that the TWC outer coating is optional and the zeolite contains a large amount of ion exchange precious metal (e.g., Pd) to replace the abundant weak physisorption (physisorption) sites in the zeolite for strong chemisorption (chemisorption) of HC and NOx and high temperature emissions storage. PNA devices are designed for use in lean (diesel) environments that may not be exposed to overheated exhaust or prolonged fuel rich modes. It has been observed that Pd increases with temperature and oxygen concentration from Pd 2+ (Desired ionic state) becomes Pd 0 (fragile metallic state). Bulk PdO can undergo this transformation at about 800°C in 21% O2, at about 690°C in 1% O2, and at about 500°C in 0.001% O2. Thus, reduction of Pd can occur at lower temperatures in the presence of less oxygen. When a reducing agent (i.e., CO, HC, H2) is present in excess of a gas-phase oxidant (O2, H2O) and PdO is preheated to a temperature sufficient to be thermally active (i.e., 200°C), Pd metal (e.g., Pd 0 ). With continued exposure to sufficiently hot exhaust and / or fuel-rich exhaust, the Pd metal in the zeolite can quickly sinter the Pd atoms into large particles and deactivate the PNA. Hot exhaust and fuel-rich operation of stoichiometric (gasoline) exhaust relative to lean (diesel) exhaust are unique, thus limiting the effectiveness of the PNA as an effective cold start emissions solution for gasoline fuels.

[0007] The LNT may contain platinum (Pt) for oxidation of NO to NO2, barium (Ba) base metal for NO2 storage, and Rh for reduction of NO2 to N2 during brief periodic fuel-rich processes. When heated to an activation temperature above about 150°C, Pt oxidizes inlet NO to NO2. In some examples, more than 90% of NOx emissions on gasoline vehicles may be in the form of NO. Ba stores inlet NO2 as Ba(NO3)2 until about 400°C when Ba(NO3)2 begins to become thermodynamically unfavorable, resulting in an equilibrium shift that begins to release stored NOx as temperature increases further. Because Ba does not store NO emissions, the NO oxidation step can be a critical first step for the LNT to capture NOx emissions. Therefore, the LNT is constrained by low temperature side kinetics and high temperature side thermodynamic equilibrium, preventing the LNT from being used as an effective cold start emissions solution.

[0008] However, the inventors have proposed a solution that at least partially addresses the above-mentioned problem of stoichiometric exhaust NOx treatment during cold start periods. In one example, the above-mentioned problem can be solved by a system comprising: a first catalyst, the first catalyst being arranged upstream of a second catalyst in a vehicle distal underbody; and a controller having computer-readable instructions stored thereon, the computer-readable instructions, when executed, enabling the controller to adjust oxygen flow to the first catalyst and the second catalyst via adjusting the intake valve of one or more engine cylinders during one or more of fuel cutoff and engine shutdown. In this way, pre-conditioning of the first catalyst and the second catalyst can be optimized to promote enhanced emissions reduction.

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

[0010] Figure 1 A schematic diagram of an engine system is shown.

[0011] Figure 2 An engine system is shown arranged in a perspective view of a vehicle, wherein an aftertreatment device of the engine system is arranged in a distal underbody of the vehicle.

[0012] Figure 3 A high level flow chart for selecting between rich or lean pre-conditioning of an aftertreatment device is shown.

[0013] Figure 4 A method for performing rich preconditioning for an aftertreatment device is shown.

[0014] Figure 5 A method for performing lean preconditioning of an aftertreatment device is shown.

[0015] Figure 6 A graph is shown demonstrating various engine and aftertreatment device conditions during pre-conditioning of the device.

[0016] Fig. 7A and Figure 7B Graphs are shown for coated monolithic samples exposed to a cold start gas species pulse including NOx, the graphs differing based on either lean or rich preconditioning of the aftertreatment device, respectively.

[0017] Fig. 8A and Figure 8B Bar graphs showing a NOx stored coated monolith heated to 700°C, where the amount of N2 produced is calculated on a g N2 / L sample basis, the graphs differing based on lean or rich preconditioning of the aftertreatment device, respectively. DETAILED DESCRIPTION

[0018] The following description relates to systems and methods for one or more aftertreatment devices disposed in a distal vehicle underbody. In one example, the one or more aftertreatment devices are disposed downstream of one or more close-coupled aftertreatment devices, such as Figure 1 In some examples, the one or more aftertreatment devices disposed in the distal vehicle underbody may be substantially identical to the one or more close-coupled aftertreatment devices. The close-coupled aftertreatment device is closer to the engine than the distal vehicle underbody aftertreatment device. Figure 1 and Figure 2 It is shown in Figure 2 The detailed position of the far side vehicle underbody catalytic converter compared to the close coupled catalytic converter is shown.

[0019] exist Figure 3 In an example of a method, a far side vehicle underbody catalyst may include a hydrocarbon trap and a three-way catalyst (TWC). In one example, the hydrocarbon trap is arranged upstream of the TWC. In this document, upstream and downstream may be used to describe the arrangement of components relative to the gas flow. In this way, the hydrocarbon trap located upstream of the TWC may receive gas before the TWC. In other words, the TWC located downstream of the hydrocarbon trap may receive gas after the hydrocarbon trap.

[0020] Figure 3 A method for preconditioning a HC trap and / or TWC for a subsequent engine start is shown in FIG. Figure 4 A method for rich preconditioning of a HC trap and / or TWC is shown. Figure 5 A method for lean preconditioning of an HC trap and / or TWC is shown. Figure 6 An exemplary engine system (such as Figure 1 Engine system) Figure 3 Graph of the method.

[0021] Fig. 7A and Figure 7B Graphs are shown for coated monolithic samples exposed to a cold start gas species pulse including NOx, the graphs differing based on either lean or rich preconditioning of the aftertreatment device, respectively. Fig. 8A and Figure 8B Bar graphs showing a NOx stored coated monolith heated to 700°C, where the amount of N2 produced is calculated on a g N2 / L sample basis, the graphs differing based on lean or rich preconditioning of the aftertreatment device, respectively.

[0022] Figure 1 to Figure 2An exemplary configuration with relative positioning of various components is shown. In at least one example, if it is shown as directly contacting each other or directly connected, then such elements can be referred to as directly contacting or directly connected, respectively. Similarly, in at least one example, the elements shown as being connected or adjacent to each other can be connected or adjacent to each other, respectively. As an example, the components laid in coplanar contact with each other can be referred to as being in coplanar contact. As another example, in at least one example, the elements positioned to be separated from each other and having only space between them without other components are referred to as such. As another example, the elements shown as being above / below each other, on the opposite sides of each other, or on the left / right sides of each other can be referred to as such relative to each other. In addition, as shown in the figure, in at least one example, the topmost element or the vertex of the element can be referred to as the "top" of the component, and the bottommost element or the bottommost point of the element can be referred to as the "bottom" of the component. As used herein, top / bottom, upper / lower, above / below can be relative to the vertical axis of the accompanying drawings and are used to describe the positioning of the elements of the accompanying drawings relative to each other. Thus, in one example, the element shown as being above other elements is positioned above other elements in the vertical direction. As yet another example, the shapes of elements depicted in the accompanying drawings may be referred to as having those shapes (e.g., such as being annular, straight, planar, curved, rounded, chamfered, angled, etc.). Additionally, in at least one example, elements shown as intersecting one another may be referred to as intersecting elements or intersecting one another. Still further, in one example, elements shown as being within another element or shown as being outside another element may be referred to as being such. It should be understood that one or more components referred to as being "substantially similar and / or identical" may differ from one another according to manufacturing tolerances (e.g., within a deviation of 1%-5%).

[0023] Figure 1 An example of a cylinder of an internal combustion engine 10 included in an engine system 7 of a vehicle 5 is depicted. Engine 10 may be controlled at least in part by a control system including controller 12 and input from a vehicle operator 130 via an input device 132. In this example, input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. Cylinder 14 of engine 10 (which may be referred to herein as a combustion chamber) may include combustion chamber walls 136 with a piston 138 positioned therein. Piston 138 may be coupled to a crankshaft 140 such that reciprocating motion of the piston is converted into rotational motion of the crankshaft. Crankshaft 140 may be coupled to at least one drive wheel of a passenger vehicle via a transmission system. Additionally, a starter motor (not shown) may be coupled to crankshaft 140 via a flywheel to enable a starting operation of engine 10.

[0024] Cylinder 14 may receive intake air via a series of intake passages 142, 144, and 146. Intake passage 146 may communicate with other cylinders of engine 10 in addition to cylinder 14. Figure 1 Engine 10 is shown configured with a turbocharger 175 including a compressor 174 arranged between intake passages 142 and 144 and an exhaust turbine 176 arranged along exhaust passage 148. Compressor 174 may be at least partially powered by exhaust turbine 176 via shaft 180. A throttle 162 including a throttle plate 164 may be disposed along the intake passage of the engine for varying the flow rate and / or pressure of intake air provided to the engine cylinders. For example, throttle 162 may be positioned downstream of compressor 174, such as Figure 1 as shown; or alternatively, may be disposed upstream of compressor 174.

[0025] Exhaust passage 148 may receive exhaust gas from other cylinders of engine 10 in addition to cylinder 14. Exhaust gas sensor 128 is shown coupled to exhaust passage 148 upstream of emission control device 178. Sensor 128 may be selected from a variety of sensors suitable for providing an indication of exhaust air-fuel ratio, such as, for example, a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen sensor), a two-state exhaust gas oxygen sensor or EGO (as depicted), a HEGO (heated EGO), nitrogen oxides (NOx), hydrocarbons (HC), or carbon oxides (CO) sensors. Emission control device 178 may be a three-way catalyst (TWC), a NOx trap, various other emission control devices, or combinations thereof.

[0026] In one example, emission control device 178 is disposed in the far vehicle underbody. In comparison, this location may be downstream of a close coupled catalyst location such as the location of first catalyst 184. In this way, first catalyst 184 is disposed upstream of emission control device 178. In one example, first catalyst 184 may be a TWC, a particulate filter (PF), a NO x Diesel oxidation catalyst, etc., or a combination thereof.

[0027] The difference between the close coupling position and the distal vehicle underbody position may include a distance from the engine, wherein the close coupling position is closer to the engine than the distal vehicle underbody position. That is, the component in the close coupling position is located upstream of the component in the distal vehicle underbody position. Additionally or alternatively, as will be referred to in Figure 2 As described in more detail, components in close-coupled locations may experience higher exhaust temperatures than components in distal vehicle underbody locations.

[0028] The second catalyst 182 may be disposed between the first catalyst 184 and the emission control device 178. The second catalyst 182 may be disposed in the far vehicle underbody. In this way, the second catalyst 182 may be closer to the emission control device 178 than the first catalyst 184. The second catalyst 182 may be a TWC, a particulate filter (PF), a NO x Diesel oxidation catalyst, hydrocarbon (HC) trap, etc., or a combination thereof.

[0029] Oxygen sensor 186 may be disposed between second catalyst 182 and emission control device 178. Oxygen sensor 186 may provide feedback to controller 12 regarding an amount of oxygen present in the exhaust flow between second catalyst 182 and emission control device 178. In some examples, feedback from controller 12 may be used to adjust the oxidation state of second catalyst 182 and emission control device 178. For example, operation of intake valve 150 may be adjusted based on feedback from oxygen sensor 186, where intake valve 150 may be moved to a fully closed position when oxidation of emission control device 178 is undesirable and / or when the second catalyst is fully oxidized.

[0030] Each cylinder of engine 10 may include one or more intake valves and one or more exhaust valves. For example, cylinder 14 is shown as including at least one intake poppet valve 150 and at least one exhaust poppet valve 156 located at an upper region of cylinder 14. In some examples, each cylinder of engine 10 (including cylinder 14) may include at least two intake poppet valves and at least two exhaust poppet valves located at an upper region of the cylinder.

[0031] Intake valve 150 may be controlled by controller 12 via actuator 152. Similarly, exhaust valve 156 may be controlled by controller 12 via actuator 154. In some cases, controller 12 may vary the signals provided to actuators 152 and 154 to control the opening and closing of the respective intake and exhaust valves. The positions of intake valve 150 and exhaust valve 156 may be determined by respective valve position sensors (not shown). The valve actuators may be electric valve actuated, or cam actuated, or a combination thereof. The intake and exhaust valve timing may be controlled simultaneously, or any possibility of variable intake cam timing, variable exhaust cam timing, dual variable cam timing, or fixed cam timing may be used. Each cam actuation system may include one or more cams and may utilize one or more of a cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) system that may be operated by controller 12 to vary valve operation. For example, cylinder 14 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation (including CPS and / or VCT). In other examples, the intake and exhaust valves may be controlled by a common valve actuator (or actuation system) or a variable valve timing actuator (or actuation system).

[0032] Cylinder 14 may have a compression ratio, which is the ratio of volume when piston 138 is at bottom dead center to volume when piston 138 is at top dead center. In one example, the compression ratio is in the range of 9:1 to 10:1. However, in some examples where different fuels are used, the compression ratio may be increased. This may occur, for example, when using a higher octane fuel or a fuel with a higher latent enthalpy of vaporization. If direct injection is used, the compression ratio may also be increased due to the effect of direct injection on engine knock.

[0033] In some examples, each cylinder of engine 10 may include a spark plug 192 for initiating combustion. Under select operating modes, ignition system 190 may provide an ignition spark to cylinder 14 via spark plug 192 in response to spark advance signal SA from controller 12. However, in some embodiments, spark plug 192 may be omitted, such as where engine 10 may initiate combustion by auto-ignition or by injection of fuel, as may be the case with some diesel engines.

[0034] In some examples, each cylinder of engine 10 may be configured with one or more fuel injectors for providing fuel thereto. As a non-limiting example, cylinder 14 is shown as including two fuel injectors 166 and 170. Fuel injectors 166 and 170 may be configured to deliver fuel received from fuel system 8. Fuel system 8 may include one or more fuel tanks, fuel pumps, and fuel rails. Fuel injector 166 is shown as being directly coupled to cylinder 14 for injecting fuel directly therein in proportion to the pulse width of signal FPW-1 received from controller 12 via electronic driver 168. In this manner, fuel injector 166 provides what is known as direct injection (hereinafter referred to as "DI") of fuel into combustion cylinder 14. Although Figure 1 Injector 166 is shown positioned on one side of cylinder 14, but injector 166 may alternatively be located on top of the piston, such as near spark plug 192. Such a location may enhance mixing and combustion when the engine is operated on alcohol-based fuels due to the lower volatility of some alcohol-based fuels. Alternatively, the injector may be located on top of and near the intake valve to enhance mixing. Fuel may be delivered to fuel injector 166 from a fuel tank of fuel system 8 via a high pressure fuel pump and a fuel rail. Additionally, the fuel tank may have a pressure sensor that provides a signal to controller 12.

[0035] Fuel injector 170 is shown arranged in intake passage 146 rather than in cylinder 14 in a configuration that provides what is known as port injection (hereinafter “PFI”) of fuel into the intake port upstream of cylinder 14. Fuel injector 170 may inject fuel received from fuel system 8 in proportion to the pulse width of signal FPW-2 received from controller 12 via electronic driver 171. It should be noted that a single driver 168 or 171 may be used for both fuel injection systems, or multiple drivers may be used, for example, driver 168 for fuel injector 166 and driver 171 for fuel injector 170, as depicted.

[0036] In an alternate example, each of fuel injectors 166 and 170 may be configured as a direct fuel injector for injecting fuel directly into cylinder 14. In yet another example, each of fuel injectors 166 and 170 may be configured as a port fuel injector for injecting fuel upstream of intake valve 150. In still other examples, cylinder 14 may include only a single fuel injector that is configured to receive different fuels from a fuel system in different relative amounts as a fuel mixture and is further configured to either inject this fuel mixture directly into the cylinder like a direct fuel injector or to inject this fuel mixture upstream of the intake valve like a port fuel injector.

[0037] During a single cycle of the cylinder, fuel may be delivered to the cylinder by two injectors. For example, each injector may deliver a portion of the total fuel injection that is burned in cylinder 14. In addition, the distribution and / or relative amount of fuel delivered from each injector may vary with operating conditions (such as engine load, knock, and exhaust temperature), such as described herein below. Port-injected fuel may be delivered during an open intake valve event, a closed intake valve event (e.g., substantially before the intake stroke), and during both open and closed intake valve operations. Similarly, direct-injected fuel may be delivered, for example, during the intake stroke, and partially during the previous exhaust stroke, during the intake stroke, and partially during the compression stroke. In this way, even for a single combustion event, the injected fuel may be injected from the port injector and the direct injector at different timings. In addition, for a single combustion event, multiple injections of the delivered fuel may be performed per cycle. Multiple injections may be performed during the compression stroke, the intake stroke, or any suitable combination thereof.

[0038] Herein, the operation of the intake valve 150 may be described in greater detail. For example, the intake valve 150 may be moved from a fully open position to a fully closed position, or to any position therebetween. For all equal conditions (e.g., throttle position, vehicle speed, pressure, etc.), the fully open position allows more air from the intake passage 146 to enter the cylinder 14 than any other position of the intake valve 150. Conversely, the fully closed position may prevent air from the intake passage 146 from entering the cylinder 14, and / or may allow a minimal amount of air to enter the cylinder 14 than any other position of the intake valve 150. Thus, positions between the fully open position and the fully closed position may allow varying amounts of air to flow between the intake passage 146 and the cylinder 14. In one example, moving the intake valve 150 to a more open position than its initial position allows more air to flow from the intake passage 146 to the cylinder 14.

[0039] Fuel injectors 166 and 170 may have different characteristics. These different characteristics include size differences, for example, one injector may have a larger spray hole than the other. Other differences include, but are not limited to, different spray angles, different operating temperatures, different targeting, different injection timing, different spray characteristics, different locations, etc. In addition, depending on the distribution ratio of the injected fuel between injectors 170 and 166, different effects may be obtained.

[0040] The fuel tank in the fuel system 8 can accommodate fuels of different fuel types, such as fuels with different fuel qualities and different fuel compositions. The differences may include different alcohol contents, different water contents, different octane numbers, different heats of evaporation, different fuel mixtures, and / or combinations thereof, etc. An example of a fuel with different heats of evaporation may include gasoline with a lower heat of evaporation as a first fuel type and ethanol with a greater heat of evaporation as a second fuel type. In another example, the engine may use gasoline as the first fuel type and use an alcohol-containing fuel mixture (such as E85 (which is about 85% ethanol and 15% gasoline) or M85 (which is about 85% methanol and 15% gasoline)) as the second fuel type. Other available substances include water, methanol, a mixture of ethanol and water, a mixture of water and methanol, an ethanol mixture, etc.

[0041] The controller 12 Figure 1 1 is shown as a microcomputer, which includes: a microprocessor unit 106, an input / output port 108, an electronic storage medium for executable programs and calibration values ​​(in this specific example, shown as a non-transitory read-only memory chip 110 for storing executable instructions), a random access memory 112, a keep alive memory 114 and a data bus. Controller 12 may receive various signals from sensors coupled to engine 10, including, in addition to those previously discussed, a measurement of inducted mass air flow (MAF) from mass air flow sensor 122; engine coolant temperature (ECT) from temperature sensor 116 coupled to cooling sleeve 118; profile ignition pickup signal (PIP) from Hall effect sensor 120 (or other type of sensor) coupled to crankshaft 140; throttle position (TP) from throttle position sensor; and manifold absolute pressure signal (MAP) from sensor 124. Engine speed signal RPM may be generated by controller 12 based on 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. Controller 12 may infer engine temperature based on the engine coolant temperature.

[0042] As mentioned above, Figure 1Only one cylinder of a multi-cylinder engine is shown. As such, each cylinder may similarly include its own set of intake / exhaust valves, one or more fuel injectors, spark plugs, etc. It should be appreciated that engine 10 may include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Furthermore, each of these cylinders may include Figure 1 Some or all of the various components described and depicted with reference to cylinder 14 .

[0043] In some examples, the vehicle 5 may be a hybrid vehicle having multiple torque sources available for one or more wheels 55. In other examples, the vehicle 5 is a conventional vehicle having only an engine. In the example shown, the vehicle 5 includes an engine 10 and an electric motor 52. The electric motor 52 may be a motor or a motor / generator. When one or more clutches 56 are engaged, the crankshaft 140 of the engine 10 and the electric motor 52 are connected to the wheels 55 via a transmission 54. In the depicted example, the first clutch 56 is disposed between the crankshaft 140 and the electric motor 52, and the second clutch 56 is disposed between the electric motor 52 and the transmission 54. The controller 12 may send a signal to the actuator of each clutch 56 to engage or disengage the clutch so as to connect or disconnect the crankshaft 140 with the electric motor 52 and the components connected thereto, and / or to connect or disconnect the electric motor 52 with the transmission 54 and the components connected thereto. The transmission 54 may be a gearbox, a planetary gear system, or other types of transmissions. The powertrain may be configured in various ways, including as a parallel, series, or series-parallel hybrid vehicle.

[0044] The electric machine 52 receives power from the traction battery 58 to provide torque to the wheels 55. The electric machine 52 may also operate as a generator to provide power to charge the battery 58, such as during braking operations.

[0045] The controller 12 is Figure 1 The various sensors receive signals and take actions based on the received signals and the instructions stored in the memory of the controller. Figure 1 For example, adjusting the flow of oxygen to the second catalyst 182 and to the emission control device may include adjusting the actuator of the intake valve 150 to adjust the oxidation of the second catalyst 182 and the emission control device 178.

[0046] Now go to Figure 2 , which shows Figure 17 of the vehicle. As such, previously introduced components may be similarly numbered in subsequent figures. The vehicle 7 includes an engine 10 fluidly coupled to a first catalyst 184, a second catalyst 182, and an emission control device 178 via an exhaust passage 148. As described above, the first catalyst 184 may be arranged in a close coupled position, and the second catalyst 182 and the emission control device 178 may be arranged in a distal vehicle underbody.

[0047] Herein, the first catalyst 184 may be referred to as a close coupled catalyst 184, the second catalyst 182 may be referred to as a hydrocarbon (HC) trap 182, and the emission control device 178 may be referred to as a three way catalyst (TWC) 178. The close coupled catalyst 184 may be located between 5-15 inches downstream of the engine 10. In some embodiments, the close coupled catalyst 184 may be located between 7-13 inches downstream of the engine 10. In some embodiments, the close coupled catalyst 184 may be located between 9-11 inches downstream of the engine 10. In one example, the close coupled catalyst is located 10 inches downstream of the engine. The HC trap 182, located downstream of the close coupled catalyst and upstream of the TWC, may be at a distance of more than 10 inches downstream of the close coupled catalyst 184. In some embodiments, the HC trap 182 is at a distance of more than 15 inches downstream of the close coupled catalyst 184.

[0048] The HC trap 182 and the TWC 178 may experience lower exhaust temperatures than the temperatures experienced by the first catalyst 184. As an example, the first catalyst 184 may experience exhaust temperatures between 840 and 880° C., while the HC trap 182 and the TWC 178 may experience exhaust temperatures between 740 and 840° C. This temperature difference may cause the first catalyst 184 to degrade faster than the HC trap 182 and the TWC 178. As such, after a threshold number of miles at which degradation of the first catalyst 184 may occur, the vehicle 7 may rely more heavily on the HC trap 182 and the TWC 178 to treat NO x and HC emissions, particularly during cold start conditions. The threshold mileage may be based on the number of miles the vehicle has traveled (e.g., 150,000 miles), which may be associated with a decrease in catalytic activity of the first catalyst 184 that is so great that it is no longer sufficient to reduce emissions to a desired amount. Thus, degradation of the first catalyst 184 may include a decrease in catalytic activity to such an extent that the first catalyst 184 is unable to treat exhaust emissions to a desired amount.

[0049] The HC trap 182 may include a porous zeolite having one or more precious or base transition metals that may be coated onto or impregnated into the zeolite. The HC trap adsorbent material may be relatively acidic to store water and hydrocarbon emissions from the engine. As an example, the HC trap adsorbent material may include an aluminosilicate zeolite having a Si to Al2 ratio of less than 40. Additionally or alternatively, the HC trap 182 may also include one or more metals that contribute to the adsorption and conversion of hydrocarbons and water. For example, the zeolite may include a framework, exchanged or impregnated metal, wherein the metal provides acidic or water adsorption characteristics, even if the Si / Al2 of the zeolite framework is greater than 40, otherwise it will have limited affinity or no affinity for water. In some examples, the zeolite may include a Si to Al2 ratio of less than 40 and one or more metals configured to contribute to water adsorption. The Si to Al2 ratio may be between 5 and 40. In some embodiments, the Si to Al2 ratio may be between 5 and 20. In some embodiments, the ratio of Si to Al2 may be between 5 and 10.

[0050] The HC trap zeolite may comprise a 20 to 100 g / ft 3 A coating of a precious group metal (PGM) of the present invention, wherein the majority of the composition of the PGM is Pd. In some embodiments, the coating may contain 20 to 70 g / ft 3 In some embodiments, the coating may contain 30 to 60 g / ft 3 In one example, there is exactly 50 g / ft 3 of PGM. The PGM may contain greater than 50% Pd. In some embodiments, additionally or alternatively, the PGM contains between 50% and 100% Pd. In some embodiments, additionally or alternatively, the PGM contains between 70% and 100% Pd. Additionally or alternatively, in some embodiments, the PGM contains between 85% and 95% Pd. In one example, there is at least 94% Pd in ​​the PGM coating. Due to the presence of an aftertreatment device downstream, the HC trap 182 may have no TWC layer (e.g., PNA), or no metal in the zeolite, or some other adsorbent material as long as it can effectively capture water.

[0051] The TWC 178 may include high loading and dispersion of catalytically active materials, including but not limited to one or more of Rh, Pd, Cu, and Ag. Although it is known to those skilled in the art that ionic Pd in ​​zeolites stores NOx in lean (diesel) exhaust applications, Rh may be preferred over Pd in ​​stoichiometric (gasoline) exhaust applications because, unlike Rh, reduced Pd prefers to adsorb CO rather than NOx. These metals may be introduced via spraying a coating onto the zeolite of the TWC 178, ion exchange of the zeolite, and / or impregnation. These catalytically active materials may be capable of forming chemically adsorbed NOx, such as nitrosyl species (e.g., Pd-NO) or dissociated species (e.g., Rh-N and Rh-O). The ... x The catalytic reduction temperature releases and / or desorbs NO x In one example, the catalytic reduction temperature is 200°C. Therefore, NOx is reduced to N2 in combination with the reductants (ie, CO, HC) present in the substoichiometric exhaust gas in the far underbody location. In other words, NO x The compound may be released from the TWC after reduction. In one example, until NO x It is reduced to N2 and then released from the TWC.

[0052] The TWC 178 may contain a high loading and dispersion of a reducible oxygen storage material such as ceria-zirconia (CZO). Once reduced, CZO provides a large number of oxygen vacancies that can be refilled at low temperatures with O from stored NOx. Adsorption of NOx onto CZO oxygen vacancies may occur without dissociation, and may require a gas phase reductant to reduce NOx to N2 with the aid of a precious metal. Alternatively, the reduced CZO may be reoxidized by O from previously dissociated NOx adsorbed on Rh, thereby creating more Rh-NOx adsorption sites.

[0053] In some examples of engine exhaust aftertreatment systems that do not currently include water adsorbing materials, the exhaust gas produced by the combustion of fuel may contain water, which may fill sites of the TWC coating material and compete with the material configured to adsorb NO. x That is, water can coordinate with the catalytically active material of TWC 178, making TWC 178 no longer in a position to adsorb NO x To address this issue, HC trap 182 is configured to capture a threshold amount of water upstream of TWC 178 so that the TWC 178 material may be able to capture NO in a relatively dry environment during cold starts where the active sites are relatively uncompeted. x Once NO xhas been adsorbed onto TWC 178, water can enter TWC 178 without replacing the chemically adsorbed NO x .

[0054] In other words, water and NO x may compete for the catalytically active material to bind to the TWC 178. However, once water or NO x In combination with the PGM of the TWC 178, they are not released until a threshold temperature (eg, 200° C.) is reached. For these reasons, the HC trap 182 and the TWC 178 may be sized to provide a temperature that is prone to high engine NOx. x output during engine conditions (e.g., cold start) to fully process NO x As an example, for a cold start duration between 0-60 seconds, the TWC 178 may be sized to capture NOx emitted by the engine during a 60 second cold start. x An equal amount of NO x Similarly, HC trap 182 may be sized to capture an amount of water that the engine releases in 60 seconds. In some examples, HC trap 182 may be sized to capture even more water than the engine releases in 60 seconds to account for factors such as ambient humidity (e.g., condensate present in vehicle plumbing). In this way, HC trap 182 may be sized to capture water for a sufficient amount of time that TWC 178 may adsorb most, if not all, of the engine output NO generated during one or more engine operating parameters. x . The HC trap 182 and the TWC 178 may be adjacent to each other. For two separately coated monolithic substrates, the outlet of the HC trap 182 and the inlet of the TWC 178 may be in coplanar contact. Alternatively, they may be zone-coated on the same monolithic substrate, with the adsorbent material (i.e., zeolite, HC trap, or PNA) in the front region and the TWC in the rear region; or they may be layered coated on the same substrate, with the TWC material below the adsorbent material; or they may be mixed together.

[0055] In one example, HC trap 182 may include a passive NOx coated with a TWC material. x Adsorber (PNA) and 50g / ft2 distributed on the adsorbent and TWC coating 3 The TWC may contain 150 g / ft 3 The PNA of the HC trap 182 may function to capture water in the exhaust gas flow, thereby enabling the TWC to capture NO x .

[0056] In some embodiments, the HC trap 182 may contain 2-7 g / in 3 of the above zeolite material, 1-4 g / in 3 TWC material (e.g., material similar to TWC 178), 0.01 wt% to 10 wt% base transition metal, and 1-200 g / ft 3 In one example, the HC trap 182 contains exactly 4.5 g / in 3 Zeolite material, 2.5g / in 3 TWC material, 1 wt% base transition metal, and 100 g / ft 3 The TWC 178 may be substantially identical to or different from the HC trap. For example, the TWC 178 may include barium hydroxide, while the HC trap 182 may not include barium hydroxide. The barium hydroxide may promote NO x Adsorption also degrades HC oxidation capabilities. With respect to precious metals, the HC trap 182 may contain a greater proportion of Pd and / or Pt, while the TWC 178 may contain a greater proportion of Rh. Thus, the difference between the two may be based on the amount of NOx that may be trapped associated with the TWC 178. x The benefits of oxidizing HC and the benefits of oxidizing HC that may be associated with the HC trap 182 arise.

[0057] As shown, the oxygen sensor 186 may be disposed between the HC trap 182 and the TWC 178. Additionally or alternatively, a gap may be disposed between the HC trap and the TWC 178, wherein the oxygen sensor 186 may be disposed in the gap.

[0058] The vehicle 7 may also include a temperature sensor 187 disposed upstream of the HC trap 182 and a temperature sensor 188 disposed downstream of the TWC 178. In one example, the engine operating parameters may be adjusted based on feedback from one or more of the temperature sensors 187, 188 and the oxygen sensor 186. For example, if one or more of the temperature sensors indicates that the TWC temperature is above the NO x If the temperature is reduced, the engine operating parameters can be adjusted so that the HC trap 182 can process HC instead of capturing water. Figure 2 These adjustments are described in more detail along with other adjustments made based on feedback from oxygen sensors.

[0059] Now go to Figure 3, which shows a method 300 for pre-conditioning the HC trap and TWC based on one or more engine operating parameters. Instructions for carrying out method 300 and the remaining methods included herein may be executed by a controller based on instructions stored on a memory of the controller and in conjunction with signals received from sensors of the engine system, such as those described above with reference to Figure 1 The controller may employ engine actuators of the engine system to adjust engine operation according to the methods described below.

[0060] In one example, in response to a close coupled catalyst (e.g., Figure 1 Method 300 and other methods included herein may be performed to determine degradation of the first catalyst 184 of the close-coupled catalyst. Degradation of one or more of the close-coupled catalysts may be determined in response to one or more of exceeding a threshold vehicle mileage, a temperature of the catalyst being below an activation threshold, and feedback from an exhaust gas sensor. For example, the exhaust gas sensor may be a NOx sensor located downstream of the close-coupled catalyst. x Sensor, where NO x The sensor senses NO leaking through the close-coupled catalyst. x As such, the close-coupled catalyst may degrade and the vehicle may begin to rely on HC traps and TWCs (eg, HC trap 182 and TWC 178 ) disposed in the far vehicle underbody.

[0061] Method 300 begins at 302, where method 300 may include determining, estimating, and / or measuring current engine operating parameters. Current engine operating parameters may include, but are not limited to, one or more of the following: catalyst temperature, engine off time, throttle position, engine temperature, engine speed, manifold pressure, vehicle speed, exhaust gas recirculation flow rate, and air-fuel ratio.

[0062] Method 300 may proceed to 304, where method 300 may include determining whether a subsequent engine start will be a cold start. The engine start may be a cold start when the engine temperature is below a threshold temperature. The threshold temperature may be equal to the fuel evaporation temperature at standard pressure, so that if the ambient engine temperature is below the fuel evaporation temperature, the engine may be cold started. Therefore, if the engine temperature is below the lower limit of the engine operating temperature range required for gasoline fuel evaporation (e.g., 88° C.), the engine may be cold started. Additionally or alternatively, the threshold temperature may be based on a desired catalyst operating temperature, where the desired catalyst operating temperature is a temperature above 200° C.

[0063] The above conditions may be determined for a subsequent engine start based on feedback from the navigation system, one or more of the temperature sensors, data stored in a lookup table, etc. For example, the navigation system may be able to determine both the current ambient temperature and a forecast for future ambient conditions (e.g., a 5-day forecast). Thus, if the ambient temperature is cold (e.g., below 20° C.), the navigation system may determine that a cold start is likely to occur at a subsequent engine restart.

[0064] Additionally or alternatively, the temperature sensor may periodically provide feedback between a previous engine shutdown and a subsequent engine start. For example, the temperature sensor may periodically provide feedback regarding the temperature of one or more of the engine coolant, the underbody HC trap, and the underbody TWC. If, for example, the engine coolant temperature drops below ambient temperature during the period between the previous engine shutdown and the subsequent engine start, then it may be determined that the subsequent engine start will be a cold start.

[0065] Additionally or alternatively, the data stored in the lookup table may be used to determine whether a subsequent engine start will be a cold start. For example, the lookup table may be a multi-input lookup table, where the conditions prior to the subsequent engine start used to look up data in the lookup table may include time of day, ambient temperature, location, etc. For example, if the vehicle is shut down at a known location where the shutdown may be greater than a threshold duration (e.g., more than 2 hours), then it may be determined that the subsequent engine start may be a cold start. Additionally or alternatively, if the engine is shut down between a certain time range (e.g., 12:00 midnight to 5:00 am), then it may be determined that the subsequent engine start will be a cold start.

[0066] If method 300 determines at 304 that the subsequent engine start will be a cold start, method 300 may proceed to 306 to perform a rich preconditioning of the HC trap and TWC disposed in the far vehicle underbody. Figure 4 Further described in .

[0067] If method 300 determines at 304 that the subsequent engine start will not be a cold start, then method 300 continues to 308 to determine whether the amount of water present at the subsequent engine start will be greater than a threshold amount of water. In one example, the threshold amount of water is based on the amount of water that an HC trap disposed in the distal vehicle underbody is configured to store. The threshold amount of water may be a non-zero number. In some examples, the amount of water that will be present at the subsequent engine start may be based on feedback from one or more of a charge air cooler (CAC) humidity sensor, an EGR cooler humidity sensor, and information stored in a lookup table. As an example, if there is greater than a threshold amount of condensate in the CAC, then the amount of water that will be present at the subsequent engine start may be greater than the threshold amount of water. As such, the HC trap may not be able to adequately capture water within a threshold amount of time (e.g., 1-60 seconds) to allow the TWC to capture a sufficient amount of NO x In other words, when the amount of water is greater than the threshold amount of water, water may leak through the HC trap, where the water may bind to the surface of the TWC and block the NO x Adsorption.

[0068] If the amount of water present at a subsequent engine start is to be greater than the threshold amount of water, method 300 may proceed from 308 to 306 to perform a rich preconditioning of the HC trap and TWC, as described with respect to Figure 4 Described in more detail.

[0069] If the amount of water present at a subsequent engine start will be less than or equal to the threshold amount of water, method 300 may proceed from 308 to 310 to perform lean preconditioning of the HC trap and / or TWC. Figure 5 Lean preconditioning of the HC trap and / or TWC is described in greater detail.

[0070] Now go to Figure 4 , which shows a method 400 for performing rich preconditioning on a HC trap and a TWC. As described above, the method 400 may be Figure 3 Thus, method 400 may begin under the following assumption: due to the high water content at the subsequent engine start, the engine NO x The output may be high and / or the TWC is NO x Adsorption capacity may be reduced. By performing a rich preconditioning, the TWC can be returned to a state more suitable for capturing NO x chemical state.

[0071] By operating continuously under slightly rich conditions, as described below Figure 4 As will be described, rich preconditioning may be achieved at the HC trap and TWC (eg, Figure 2Due to oxygen consumption at the close-coupled catalyst (e.g., first catalyst 184), exhaust conditions downstream of the close-coupled catalyst may be richer than exhaust conditions upstream of the close-coupled catalyst. As such, operating under slightly lean conditions may include operating with a lambda value between 0.95 and 1.05, the lambda value being estimated by an exhaust gas sensor located upstream of the close-coupled catalyst. The reductant (CO, CH4) may flow to the HC trap and the TWC, where the reductant may regenerate one or more materials of the HC trap and the TWC.

[0072] Method 400 begins at 402, where method 400 may include: burning under slightly rich conditions. Burning under slightly rich conditions may include an air-fuel ratio less than 1.0. As known to those of ordinary skill in the art, an air-fuel ratio of 1.0 corresponds to a stoichiometric air-fuel ratio, an air-fuel ratio less than 1.0 is considered rich, and an air-fuel ratio greater than 1.0 is considered lean. A rich air-fuel ratio has a relatively greater amount of fuel than a lean air-fuel ratio. The range of air-fuel ratios for combustion occurring under slightly rich conditions is 0.9 to 0.99. In some embodiments, the range is 0.93 to 0.99. In some embodiments, additionally or alternatively, the range is 0.95 to 0.99. In one example, slightly rich combustion is exactly 0.95. In one example, combustion under slightly rich conditions is achieved during all combustion conditions of the engine. Therefore, combustion under slightly rich conditions may occur during high load, medium load, low load, idling, etc. During a fuel cut event (e.g., DFSO, start / stop, etc.), intake valve operation may be adjusted such that the intake valve is less open and / or closed. In one example, intake valve operation during a fuel cut is in a fully closed position where intake air does not flow to the combustion chamber (e.g., Figure 1 By doing so, a rich exhaust environment can flow continuously through the aftertreatment device (e.g., Figure 2 HC trap 182 and TWC 184), thereby reducing the reactive elements arranged thereon.

[0073] Method 400 may proceed to 404, where the method may include monitoring air flow to the underbody of the far vehicle. Figure 2 As depicted, the far vehicle underbody may include an HC trap 182 and a TWC 178. The amount of air flowing to the aftertreatment device may be based on the amount of air flowing from the first catalyst disposed directly thereon (e.g., Figure 2The intake valve may be estimated based on feedback from at least one oxygen sensor downstream of the first catalyst 184. In some examples, intake valve operation may be adjusted in response to the amount of air flowing to the aftertreatment device. For example, if the amount of air is too high to allow rich preconditioning to reduce the aftertreatment device, the intake valve may be moved to a more closed position to reduce the amount of air flowing.

[0074] Method 400 may proceed to 406, where the method includes determining whether the aftertreatment device is sufficiently restored. In some embodiments, the determination may be based on data stored in a multi-input lookup table, where the inputs may include vehicle mileage, engine NO x output, exhaust humidity, exhaust temperature, etc. In some embodiments, additionally or alternatively, the determination may be based on performing lean preconditioning for a threshold amount of time, where the threshold amount of time is based on an amount of time sufficient to operate under slightly rich conditions and restore the aftertreatment device. The threshold amount of time may decrease in response to a richer rich preconditioning, and may increase in response to a less rich preconditioning. Additionally or alternatively, the threshold amount of time may increase in response to an amount of air flowing to the aftertreatment device.

[0075] If the device is not sufficiently restored, the method may continue to perform rich preconditioning. If the device is sufficiently restored, rich preconditioning may be terminated and the air-fuel ratio may be adjusted based on driver demand and / or other engine operating conditions.

[0076] In some embodiments, additionally or alternatively, method 400 may include one or more prediction conditions in which rich preconditioning is performed in an intrusive manner. For example, the prediction condition may include determining whether an engine shutoff event occurs within a threshold. The threshold may be based on one or more of a threshold amount of time, a threshold mileage, or a combination of the two. The threshold time may be based on an amount of time previously determined to be sufficient to complete rich preconditioning of the HC trap and TWC. Similarly, the threshold mileage may be based on the mileage required to complete rich preconditioning of the HC trap and TWC. However, it should be understood that rich preconditioning may occur during an idling vehicle event or other vehicle event in which the movement of the car is substantially zero. A destination may be entered into a navigation system, where the threshold for the engine shutoff event may be based on a specific location along the route to the destination. The specific location may be associated with completing 90%-95% of the route. In this way, 5%-10% of the route may be used to perform rich preconditioning. Additionally or alternatively, the threshold may be a time before the vehicle reaches a stop light.

[0077] Additionally or alternatively, if a destination has not been entered into the navigation system, the navigation system may predict an expected final destination. Predicting the final destination may include monitoring a current route taken by a vehicle driver and comparing the current route to a known route stored in memory or a route determined in real time. As an example, the navigation may determine in real time a route between a current vehicle location and a saved known destination (e.g., "home"). If the current route matches the route determined in real time, the vehicle may predict that the saved known destination is the same as the expected final destination.

[0078] Now go to Figure 5 , which shows a method 500 for performing lean preconditioning on an aftertreatment device. Lean preconditioning may allow the HC trap to release HC stored thereon.

[0079] Method 500 Figure 3 Method 300 of starts at 502 after 310, where method 500 may include: burning under slightly lean conditions. Burning under slightly lean conditions may include burning at a lambda at or above 1.0. In some embodiments, the lambda value may be between 1.0 and 1.1. In some embodiments, additionally or alternatively, the lambda value may be between 1.0 and 1.05. In some embodiments, additionally or alternatively, the lambda value may be between 1.0 and 1.02. Burning under slightly lean conditions may include adjusting one or more engine operating parameters, where the one or more engine operating parameters may include adjusting the throttle to a more open position, reducing the initial injection pressure, reducing the secondary injection pressure, and increasing the intake valve opening.

[0080] Method 500 may proceed to 504, where method 500 may include adjusting the intake valve position during DFSO and / or other fuel cut events. The adjustment may include moving the intake valve to a more open position so that more intake air can flow through the unfueled cylinder. By doing so, the air concentration in the exhaust passage may be increased.

[0081] Method 500 may proceed to 506, where method 500 may include determining whether the aftertreatment device is sufficiently oxidized. The determination may be based on the amount of airflow flowing to the distal vehicle underbody. The amount may be estimated based on feedback from an oxygen sensor disposed between the first catalyst and the HC trap. Additionally or alternatively, the determination may be based on data stored in a multi-input lookup table, where a combination of intake valve position, throttle position, and duration of each of a lean burn combustion event and a fuel cutoff event may be used to determine whether the aftertreatment device has received an amount of air sufficient to be oxidized to a desired amount.

[0082] If the aftertreatment device is not sufficiently oxidized, method 500 may proceed to 508 to continue lean preconditioning. If the aftertreatment device is sufficiently oxidized, method 500 may proceed to 510 to adjust the air-fuel ratio and therefore the measured lambda value based on the engine operating parameters. However, the exhaust flow to the far vehicle underbody may continue to be measured to ensure that the lean preconditioning is not cancelled due to future engine operating parameters. For example, if the engine operating parameters are adjusted to rich engine conditions, the lean preconditioning may be cancelled and the aftertreatment device is no longer in an oxidized state. In some examples, the controller may relay a prompt to the driver via the navigation system to warn the driver to adjust the current driving behavior. Additionally or alternatively, the controller may intrusively adjust the current operating parameters to prevent the aftertreatment device from being restored after the lean preconditioning.

[0083] In some examples of method 500 , it may be undesirable to flow oxygen to the TWC because this would oxidize the catalyst stored in the TWC, which could reduce the ability of the TWC to capture NO. x Therefore, for some embodiments of method 500, an oxygen sensor may be arranged between the HC trap and the TWC, wherein the oxygen sensor may provide feedback regarding oxygen leakage through the HC trap. If the oxygen leakage reaches a value greater than a threshold leakage, method 500 may determine that the HC trap is sufficiently oxidized and may terminate lean preconditioning to avoid oxidizing the TWC. The threshold leakage may be based on a non-zero positive number.

[0084] Now go to Figure 6 , which shows a graph 600 illustrating rich preconditioning and lean preconditioning after a cold start to return the TWC and HC trap to a desired reaction state. Curve 610 represents engine temperature and dashed line 612 represents threshold cold start temperature, curve 620 represents intake valve position, curve 630 represents lambda value and dashed line 632 represents stoichiometric lambda value, curve 640 represents water mass flow and dashed line 642 represents the TWC trapping NOx which may be detrimental to the TWC. x 600 represents a threshold flow rate of water with a capacity of 100, curve 650 represents a TWC oxidation state and dashed line 652 represents a reaction state of the TWC where the TWC is fully reduced, and curve 660 represents an HC trap oxidation state and dashed line 662 represents a threshold oxidation corresponding to full oxidation of the HC trap. Time is shown on the x-axis of graph 600, where time gradually increases from the left side of the graph to the right side.

[0085] Prior to t1, the engine temperature (curve 610) is below the threshold cold start temperature (dashed line 612). Therefore, a cold start is occurring. The intake valve position (curve 620) is shown as oscillating between an open position and a closed position. λ is greater than the stoichiometric λ (curve 630 and dashed line 632, respectively). The mass flow rate of water (curve 640) is greater than the threshold flow rate of water (dashed line 642), where the water can weaken the effect of the TWC and prevent it from capturing NO during a cold start. x The TWC oxidation (curve 650) is above the threshold reduction (dashed line 652), indicating that the TWC has been sufficiently reduced to capture NO x HC trap oxidation (curve 660 ) ​​is less than a threshold oxidation (curve 662 ), indicating that the HC trap may be substantially free of HC.

[0086] As the cold start continues, the HC trap captures water, while the TWC captures NO released by the engine during the cold start. x In this way, the TWC may be oxidized and its oxidation state may be reduced below the threshold reduction.

[0087] At t1, the cold start is complete, as indicated by the engine temperature being above the threshold cold start temperature. Intake valve operation continues to oscillate between open and closed. The mass flow of water is below the threshold flow of water. The TWC is oxidized and its oxidation state is below the threshold reduced. The HC trap is oxidized and its oxidation state is below the threshold oxidized.

[0088] Between t1 and t2, rich preconditioning may be performed, wherein intake valve operation may be adjusted such that the intake valve moves to a less open position to allow less intake air to flow to the far vehicle underbody. As a result, both the TWC and the HC trap may begin to reduce. Thus, TWC oxidation increases toward a threshold reduction, and HC trap oxidation increases to exceed a threshold oxidation due to its capture of some fuel in the exhaust gas.

[0089] At t2, an engine fuel cut event occurs while rich preconditioning is being performed. As a result, the intake valve moves to a fully closed position to block airflow through the exhaust system.

[0090] Between t2 and t3, the fuel cut event continues with the intake valve maintained in a closed position. The TWC and HC trap each continue to regenerate.

[0091] At t3, the TWC reaches a reduced state above a threshold reduced, indicating that the TWC is sufficiently reduced. As a result, rich preconditioning may be performed. However, the HC trap is in an oxidized state above a threshold oxidized, indicating that the HC trap may not be able to adequately trap HC. Therefore, lean preconditioning may be initiated.

[0092] Between t3 and t4, the fuel cut event continues, and therefore, the intake valve position is adjusted such that the intake valve is maintained in a fully open position to allow more intake air flow therethrough. As the intake air flows to the far vehicle underbody, the air may oxidize the HC stored on the HC trap, thereby oxidizing the HC trap and moving its oxidation state closer to the threshold oxidation. Additionally, by oxidizing the HC, CO may be released, which may further reduce the TWC, as indicated by the TWC oxidation state becoming more reduced.

[0093] At t4, the HC trap oxidation state may be below a threshold oxidation, causing the intake valve position to move to a fully closed position. In one example, the HC trap oxidation state is estimated to be below the threshold oxidation in response to air leakage measured downstream of the HC trap and upstream of the TWC. Therefore, to prevent oxidation of the TWC, the intake valve may be moved to a fully closed position, or the position of the intake valve may be adjusted based on engine operating parameters. In any case, lean preconditioning is terminated.

[0094] After t4, the engine is shut down. The engine temperature drops to ambient temperature, and because the intake valve remains in the fully closed position, no air can flow to the far vehicle underbody.

[0095] Now go to Fig. 7A , Figure 7B , Fig. 8A and Figure 8B , the coated cordierite monolithic samples were tested in the laboratory for their NOx adsorption and conversion potential. Fig. 7A , Figure 7B , Fig. 8A and Figure 8B Figure 7 and Fig. 8A Graphs 700 and 800 , respectively, depict the results for lean preconditioning, and graphs 750 and 850 , respectively, depict the results for rich preconditioning.

[0096] All samples were exposed to an aging environment in an oven at 760°C fed with isooctane fuel combustion products and with oxygen injection control that increased the reaction temperature above the sample from 740°C to 840°C in a 1 minute cycle for a duration of 50 hours. This process caused aftertreatment devices located in far underbody locations (e.g., Figure 2Full life level degradation of the HC trap 182 and TWC 178). A single core sample of 17.5 mm diameter by 25.4 mm length was placed just outside the oven heating zone wrapped in a mat material. To pre-condition the sample for testing, the oven was heated to a sample temperature of 700°C and then 2 volume % O2 was turned on for 120 seconds to allow the sample to fully oxidize. Finally, the sample was cooled to 30°C, the O2 was turned off, and the sample was considered pre-conditioned in a lean burn state (lean pre-conditioning) and ready for the next test. Alternatively, before the oxidized sample cools down, the O2 is turned off and the sample is cooled to 400°C, then 1% CO / H2 is turned on for 300 seconds to allow the sample to be mostly reduced, and finally the CO / H2 is turned off, and the sample is considered pre-conditioned in a rich burn state (rich pre-conditioning) and ready for the next test. With the sample initially at 30°C, a heated feed stream of 10% by volume H2O vapor and the balance N2 was delivered to the sample for 30 seconds to simulate ambient humidity exposure. The feed stream was then changed to a feed stream for a flow reactor NOx adsorption experiment and at 3L / min, consisting of 200ppm of NO, 2400ppm of CO, 800ppm of H2, 160ppm of benzene, 160ppm of isooctane and 160ppm of toluene, 10% by volume H2O vapor and the balance of air. The 3-part HC blend brings the total HC to 3360ppm of C1. This gas composition was selected to simulate cold start exhaust emissions entering a far underbody location and introduced to the sample initially at 30°C for 30 seconds. The feed stream is then changed into a feed stream for flow reactor programmed temperature desorption (temperature programmed desorption, TPD) experiment and is at 3L / min, which is composed of 50ppm of CO, 18ppm of H2, 10% of H2O vapor and surplus N2. This gas composition is selected to simulate the preheated exhaust emissions entering the far side underbody position. When the oven is heated to 700℃ and maintained at 60℃ / m at the injection port, the gas feed is introduced into the sample. After 600s of total TPD time, H2O vapor is turned off and the sample is pre-conditioned to the desired conditions. MKS Fourier Transform Infra-Red (FTIR) analyzer is used downstream of the oven to measure individual NOx gas species (NO, NO2, N2O and NH3) and enable calculation of the formation of N2.

[0097] Fig. 7A and Figure 7BIt is shown that the tested TWC and HC trap samples individually have difficulty storing NOx in a simulated cold start environment, however, the combination of the two samples in series (HC trap and then TWC) is proven to have a superior NOx adsorption capacity that exceeds the simple sum of the NOx storage capacity of the individual samples, such as Fig. 7A Block 710 and Figure 7B As shown by the improved adsorption depicted within box 760 of . Thus, the water adsorption capacity of the upstream HC trap promotes NOx storage on the downstream TWC. As evidence, when water is completely removed from the test procedure, the TWC sample exhibits full inlet NOx adsorption efficiency. This also indicates that sample preconditioning has little effect on inlet NOx adsorption.

[0098] Fig. 8A and Figure 8B It is shown that the tested TWC and HC trap samples individually have difficulty converting stored NOx to N2 in a simulated warmed exhaust environment, however, the combination of the two samples in series (HC trap, then TWC) is demonstrated to have superior NOx to N2 conversion over the simple sum of the individual sample N2 conversion amounts. Thus, the water adsorption capacity of the upstream HC trap improves stored NOx conversion on the downstream TWC. As evidence, when water is completely removed from the test procedure, the TWC sample exhibits higher stored NOx conversion efficiency than the combination. This also shows that rich sample preconditioning significantly improves the conversion of stored NOx species to N2 on the sample.

[0099] In one example, a vehicle including an aftertreatment device in the far vehicle underbody was tested for emissions according to the Federal Test Procedure (FTP-4) on a single drum chassis dynamometer test cell. The battery state of charge was 16% at the start of the test. The fuel used was LEV-III gasoline with 10% ethanol. The underbody system was either a production TWC, or an HC trap followed by a TWC after a 2 inch gap. The HC trap and TWC systems used the same coating as described above. The catalyst was aged to simulate full service life conditions of 150,000 miles.

[0100] Table 1 lists the regulated tailpipe emissions for the two exhaust systems during the first phase of the FTP4 test, including the cold start portion. During the first phase of the FTP-4 emissions test, the HC Trap + TWC underbody system reduced HC emissions by 10 mg / mi and reduced NOx emissions by 10 mg / mi. The 5 test average results for the HC Trap + TWC underbody system are a blend of the tests using the FTP4 cycle as well as the pre-conditioning of the US06 cycle.

[0101]

[0102] Table 2 lists the regulated tailpipe emissions for both systems during the first 160 seconds of the FTP4 test (which is the cold start portion). Instead of a potentially interfering exhaust ambient perturbation as previously described, the results were preconditioned using either the FTP4 cycle or the US06 cycle. As a comparison, the amount of CO entering the underbody location during the final phase of FTP-4 (868 seconds) was 0.4 g, while during US06 (600 seconds) it was 6.8 g. Therefore, the underbody system conditioned with the US06 cycle can be considered more reduced than conditioned with the FTP4 cycle. During the first 60 seconds of the FTP-4 emissions test, the production TWC system may not store NOx emissions, but the HC trap + TWC underbody system together stored 38-43 mg of NOx, regardless of preconditioning. However, the distribution of stored NOx on either device was shifted by preconditioning. Rich preconditioning results in diverting more NOx past the HC trap to the TWC, which can convert the stored NOx at a higher conversion efficiency than the HC trap.

[0103]

[0104]

[0105] In this way, a distal vehicle underbody disposed downstream of one or more close-coupled aftertreatment devices may include a HC trap disposed upstream of a TWC. The HC trap may contain water adsorbing material to reduce and / or prevent water from flowing to the TWC. The technical effect of configuring the HC trap to capture water is to prevent water from chemically adsorbing onto the surface of the TWC during a cold start. Thus, the TWC may capture NO during a cold start. x , thereby reducing NO x Additionally, due to the location of the HC trap and TWC, degradation of the HC trap and TWC may be delayed and / or prevented, and the aftermarket device may maintain catalytic activity well after the close coupled catalyst has degraded and is no longer catalytically active.

[0106] An example of a system includes: a hydrocarbon trap located upstream of a three-way catalyst in an underbody of a vehicle, wherein the underbody of the vehicle is a threshold distance downstream of an aftertreatment device closely coupled to the engine; and a controller having computer readable instructions stored on a non-transitory memory that, when executed, enable the controller to generate NOx generated upon subsequent engine start-up. xThe first example of the system further includes: wherein the hydrocarbon trap includes an adsorbent material configured to store water and hydrocarbons. The second example of the system, optionally including the first example, further includes: wherein the three-way catalyst includes a material configured to store NOx during a cold start of the engine, and wherein the material stores the NOx after the cold start of the engine. x into N2. A third example of the system, optionally including the first example and / or the second example, further includes: wherein the threshold distance is between 10 inches and 20 inches. A fourth example of the system, optionally including one or more of the first to third examples, further includes: wherein the threshold distance is between 13-17 inches. A fifth example of the system, optionally including one or more of the first to fourth examples, further includes: wherein the controller responds to the NO generated at the subsequent engine start x The amount is greater than the threshold NO x The engine intake valve operation is adjusted, wherein the adjustment includes moving the intake valve to a more closed position to reduce the three-way catalyst. A sixth example of the system, optionally including one or more of the first to fifth examples, further includes: wherein the adjustment also includes moving the intake valve to a fully closed position during a fuel cut-off event. A seventh example of the system, optionally including one or more of the first to sixth examples, further includes: wherein the adjustment includes moving the intake valve to a more open position to oxidize the hydrocarbon trap.

[0107] An example of a method includes: performing rich preconditioning on a hydrocarbon trap and a three-way catalyst in response to a subsequent engine start being a cold start; and estimating air flow based on feedback from a sensor disposed downstream of a close-coupled catalyst, the close-coupled catalyst disposed upstream of the hydrocarbon trap and the three-way catalyst relative to the direction of exhaust gas flow. The first example of the method also includes: performing the rich preconditioning in response to an amount of water present at the subsequent engine start being greater than a threshold amount of water, wherein the threshold amount of water is based on a size of the TWC and an estimated engine NO at the subsequent engine start. xoutput. A second example of the method, optionally including the first example, further includes: wherein the amount of water is estimated via a charge air cooler condensate level, current ambient humidity, and a future weather forecast. A third example of the method, optionally including the first example and / or the second example, further includes: wherein the rich preconditioning includes a lambda value between 0.95 and 0.99. A fourth example of the method, optionally including one or more of the first to second examples, further includes: wherein the rich preconditioning is terminated in response to the three-way catalyst reaching a threshold reduction state. A fifth example of the method, optionally including one or more of the first to fourth examples, further includes: wherein after the termination of the rich preconditioning, a lean preconditioning is performed on the HC trap, wherein the lean preconditioning includes a lambda value between 1.0 and 1.1. A sixth example of the method, optionally including one or more of the first to fifth examples, further includes: wherein the lean preconditioning is terminated in response to feedback from an oxygen sensor disposed between the HC trap and the TWC, wherein the oxygen sensor monitors oxygen leakage through the HC trap. A seventh example of the method, optionally including one or more of the first to sixth examples, further includes: wherein the HC trap includes a passive NO x Adsorber.

[0108] An example of a system includes: an engine; a close-coupled catalyst disposed less than 12 inches from the engine in an exhaust passage configured to receive exhaust gas from the engine; a hydrocarbon trap located upstream of a three-way catalyst, the hydrocarbon trap disposed at a distance greater than or equal to 15 inches downstream of the close-coupled catalyst relative to the direction of exhaust gas flow; and a controller having computer-readable instructions stored on its non-transitory memory, the computer-readable instructions, when executed, enabling the controller to: perform a rich preconditioning, the rich preconditioning including a lambda between 0.95 and 0.99; and perform a lean preconditioning after the rich preconditioning, wherein the lean preconditioning includes a lambda between 1.0 and 1.1. The first example of the system further includes: wherein the rich preconditioning also includes adjusting intake valve operation during a fuel cut event, the adjusting including moving an intake valve of the engine to a less open position or a fully closed position. A second example of the system, optionally including the first example, further includes: wherein the lean preconditioning also includes adjusting intake valve operation during a fuel cut-off event, the adjustment including moving the intake valve of the engine to a more open position or a fully closed position. A third example of the system, optionally including the first example and / or the second example, further includes: wherein the lean preconditioning is terminated in response to an amount of oxygen flowing through the hydrocarbon trap to the three-way catalyst being greater than a threshold oxygen leakage amount. A fourth example of the system, optionally including one or more of the first to third examples, further includes: wherein the hydrocarbon trap contains 50 g / ft 3 Pd / Rh, and wherein the three-way catalyst contains 150g / ft 3 Pd / Rh.

[0109] It should be noted that the exemplary control and estimation routines included herein can be used with various engine and / or vehicle system configurations. The control methods and routines disclosed herein can be stored as executable instructions in a non-transitory memory and can be implemented by a control system including a controller in combination with various sensors, actuators and other engine hardware. The specific routines described herein may represent one or more of any number of adjustment strategies (such as event-driven, intermittently driven, multi-tasking, multi-threading, etc.). In this way, the various actions, operations and / or functions shown can be performed in the order shown, can be performed in parallel, or in some cases, can be omitted. Similarly, the adjustment order is not necessarily required to achieve the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations and / or functions shown can be repeatedly performed according to the specific strategy used. In addition, the described actions, operations and / or functions can graphically represent the code in the non-transitory memory of the computer-readable storage medium to be programmed into the engine control system, wherein the described actions are implemented by executing the instructions in a system including various engine hardware components in combination with an electronic controller.

[0110] It should be understood that the configurations and routines disclosed herein are exemplary in nature, and these specific embodiments should not be considered in a limiting sense, as many variations are possible. For example, the above technology can be applied to V-6, inline 4, inline 6, V-12, opposed 4, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or characteristics disclosed herein.

[0111] The following claims particularly point out certain combinations and subcombinations that are considered novel and non-obvious. These claims may refer to "an" element or "a first" element or the equivalent thereof. Such claims should be understood to include the incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or characteristics may be claimed by amendment of the present claims or by presenting new claims in this or a related application. Such claims are also considered to be included in the subject matter of the present disclosure, whether broader, narrower, the same, or different in scope than the original claims.

[0112] According to the present invention, a system is provided having: a hydrocarbon trap located upstream of a three-way catalyst in an underbody of a vehicle, wherein the underbody of the vehicle is a threshold distance downstream of an aftertreatment device closely coupled to the engine; and a controller having computer readable instructions stored on a non-transitory memory, the computer readable instructions when executed enabling the controller to respond to NO generated upon subsequent engine start-up. x The engine intake valve operation is adjusted according to the amount.

[0113] According to one embodiment, the hydrocarbon trap comprises an adsorbent material configured to store water and hydrocarbons.

[0114] According to one embodiment, the three-way catalyst comprises a material configured to store NOx during a cold start of the engine, and wherein the material converts the NOx into a x Converted into N2.

[0115] According to one embodiment, the threshold distance is between 10 inches and 20 inches.

[0116] According to one embodiment, the threshold distance is between 13-17 inches.

[0117] According to one embodiment, the controller responds to the NO generated at the subsequent engine start. x The amount is greater than the threshold NO x The engine intake valve operation is adjusted, wherein the adjustment includes moving the intake valve to a more closed position to reduce the three-way catalyst.

[0118] According to one embodiment, the adjusting further comprises moving the intake valve to a fully closed position during a fuel cut event.

[0119] According to one embodiment, the adjusting comprises moving the intake valve to a more open position to oxidize the hydrocarbon trap.

[0120] According to the present invention, a method includes: performing rich preconditioning of a hydrocarbon trap and a three-way catalyst in response to a subsequent engine start being a cold start; and estimating air flow based on feedback from a sensor arranged downstream of a close-coupled catalyst, the close-coupled catalyst being arranged upstream of the hydrocarbon trap and the three-way catalyst relative to a direction of exhaust gas flow.

[0121] According to one embodiment, the above invention is further characterized by performing the rich preconditioning in response to the amount of water present at the subsequent engine start being greater than a threshold amount of water, wherein the threshold amount of water is based on the size of the TWC and the estimated engine NO at the subsequent engine start. x The combination of outputs.

[0122] According to one embodiment, the amount of water is estimated via the charge air cooler condensate level, the current ambient humidity and a future weather forecast.

[0123] According to one embodiment, the rich pre-conditioning comprises a lambda value between 0.95 and 0.99.

[0124] According to one embodiment, the above invention is further characterized by terminating the rich pre-conditioning in response to the three-way catalyst reaching a threshold reduction state.

[0125] According to one embodiment, the above invention is further characterized by performing a lean preconditioning of the HC trap after said termination of said rich preconditioning, wherein said lean preconditioning comprises a lambda value between 1.0 and 1.1.

[0126] According to one embodiment, the lean preconditioning is terminated in response to feedback from an oxygen sensor arranged between the HC trap and the TWC, wherein the oxygen sensor monitors oxygen leakage through the HC trap.

[0127] According to the present invention, a system is provided, which has: an engine; a close-coupled catalyst, which is arranged at a distance of less than 12 inches from the engine in an exhaust passage configured to receive exhaust gas from the engine; a hydrocarbon trap, which is located upstream of a three-way catalyst, and the hydrocarbon trap is arranged at a distance greater than or equal to 15 inches downstream of the close-coupled catalyst relative to the direction of the exhaust gas flow; and a controller, which has computer-readable instructions stored on its non-transitory memory, and the computer-readable instructions, when executed, enable the controller to: perform rich pre-conditioning, the rich pre-conditioning including a lambda between 0.95 and 0.99; and perform lean pre-conditioning after the rich pre-conditioning, wherein the lean pre-conditioning includes a lambda between 1.0 and 1.1.

[0128] According to one embodiment, the rich pre-conditioning further comprises adjusting intake valve operation during a fuel cut event, the adjusting comprising moving an intake valve of the engine to a less open position or a fully closed position.

[0129] According to one embodiment, the lean preconditioning further comprises adjusting intake valve operation during a fuel cut event, the adjusting comprising moving an intake valve of the engine to a more open position or a fully closed position.

[0130] According to one embodiment, the lean preconditioning is terminated in response to an amount of oxygen flowing through the hydrocarbon trap to the three-way catalyst being greater than a threshold oxygen leakage amount.

[0131] According to one embodiment, the hydrocarbon trap contains 50 g / ft 3 Pd / Rh, and wherein the three-way catalyst contains 150g / ft 3 Pd / Rh.

Claims

1. A system for an exhaust gas aftertreatment device, comprising: a hydrocarbon trap located upstream of a three-way catalyst in an underbody of the vehicle, wherein the underbody of the vehicle is a threshold distance downstream of an aftertreatment device closely coupled to the engine; as well as A controller having computer readable instructions stored on a non-transitory memory, the computer readable instructions, when executed, enabling the controller to: In response to the NO generated during subsequent engine start x Adjusting engine intake valve operation according to the amount of Rich preconditioning of the hydrocarbon trap and the three-way catalyst is performed in response to an amount of water being present at the subsequent engine start being greater than a threshold amount of water.

2. The system of claim 1, wherein the hydrocarbon trap comprises an adsorbent material configured to store water and hydrocarbons.

3. The system of claim 1, wherein the three-way catalyst comprises a material configured to store NOx during a cold start of the engine, and wherein the material converts the NOx to x Converted into N2.

4. The system of claim 1, wherein the threshold distance is between 10 inches and 20 inches.

5. The system of claim 1, wherein the threshold distance is between 13 inches and 17 inches.

6. The system of claim 1, wherein the controller is responsive to the NO generated at the subsequent engine start. x The amount is greater than the threshold NO x The engine intake valve operation is adjusted, and wherein the adjustment includes moving the intake valve to a more closed position to reduce the three-way catalyst.

7. The system of claim 6 wherein said adjusting further comprises moving said intake valve to a fully closed position during a fuel cut event.

8. The system of claim 6 wherein said adjusting includes moving said intake valve to a more open position to allow oxidation of said hydrocarbon trap.

9. A method for an exhaust aftertreatment device, comprising: performing rich preconditioning of a hydrocarbon trap and a three-way catalyst in response to a subsequent engine start being a cold start; estimating air flow based on feedback from a sensor disposed downstream of a close-coupled catalyst disposed upstream of the hydrocarbon trap and the three-way catalyst relative to a direction of exhaust gas flow; as well as The rich preconditioning is performed in response to an amount of water present at the subsequent engine start being greater than a threshold amount of water, wherein the threshold amount of water is based on a size of the three-way catalyst and an estimated engine NOx at the subsequent engine start. x The combination of outputs.

10. The method of claim 9, wherein the amount of water is estimated via charge air cooler condensate level, current ambient humidity, and future weather forecasts.

11. The method of claim 9, wherein the rich preconditioning comprises a lambda value between 0.95 and 0.

99.

12. The method of claim 9, further comprising: The rich pre-conditioning is terminated in response to the three-way catalyst reaching a threshold reduction state.

13. The method of claim 12, further comprising: After said termination of said rich preconditioning, a lean preconditioning of said hydrocarbon trap is performed, wherein said lean preconditioning includes a lambda value between 1.0 and 1.

1.

14. The method of claim 13, wherein the lean preconditioning is terminated in response to feedback from an oxygen sensor disposed between the hydrocarbon trap and the three-way catalyst, wherein the oxygen sensor monitors oxygen leakage through the hydrocarbon trap.

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