Water injection for catalyst oxygen reduction and catalyst temperature control during transient events

Abstract

Power engine process, which includes the following: Selective deactivation of one or more engine cylinders via deactivatable fuel injectors during a transmission event; and during cylinder deactivation, injection of water into the one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst, wherein, during cylinder deactivation, the injection of water into the one or more cylinders includes the injection of water into the one or more cylinders in response to a number of water injection cycles exceeding a threshold.

Description

[0001] This application relates to catalyst regeneration and catalyst temperature control using water injection during lean events.

[0002] Engine exhaust aftertreatment systems can include one or more catalysts to address various exhaust components. These can include, for example, three-way catalysts, NOx storage catalysts, start-up catalysts, SCR catalysts, and so on. Engine exhaust catalysts can utilize periodic regeneration to restore catalytic activity and reduce catalyst oxidation. Catalysts can be regenerated, for example, by injecting sufficient fuel to create a rich environment and reduce the amount of oxygen stored in the catalyst. Because the fuel consumed during catalyst regeneration can impair engine fuel economy, various catalyst regeneration strategies have been developed.

[0003] An example method is shown by Georigk et al. in US 6,969,492 B1. In this method, an exhaust gas purification device comprises catalyst stages generated by at least two catalysts arranged in series. Specifically, the catalyst stages include a three-way catalyst arranged in series with (e.g., upstream of) a NOx reduction catalyst. The different ammonia storage capacities of the various catalysts allow for improved NOx reduction and reduce the need for catalyst regeneration. Another example method is shown by Eckhoff et al. in WO 2009 / 080152 A1.This includes an engine exhaust system comprising several NOx storage catalysts with an intermediate SCR catalyst, and an exhaust air / fuel ratio is continuously changed between rich and lean phases based on differences between an air / fuel ratio upstream of a first NOx storage catalyst and an air / fuel ratio downstream of a second NOx storage catalyst.

[0004] However, the inventors have identified potential problems with such methods. For example, they have recognized that regeneration control can degrade during operations where one or more cylinders are deactivated by cutting off the fuel supply to those cylinders during a vehicle driving cycle. During these operations, while the engine is deactivated and the fuel supply is cut off to improve drivability and performance, the engine may continue to rotate. This rotation pumps air over an exhaust three-way catalytic converter, causing the converter to oxidize and impairing its ability to reduce NOx when the engine is reactivated. And although enrichment can be used to quickly regenerate the three-way catalytic converter upon engine reactivation, this enrichment results in a fuel disadvantage.Another consequence of the engine pumping air over the catalyst can include an increase in catalyst temperature, which further degrades catalyst performance.

[0005] German patent application DE 10 2014 105 128 A1 provides a method for injecting water during engine cylinder deactivation to reduce the need for exhaust catalyst regeneration. US patent application 7 877 189 B2 describes a method for an engine with a delivery system configured to supply fuel and a liquid containing at least some water to an engine cylinder. German patent application DE 10 2006 041 520 A1 describes a method for controlling an engine and an additional torque device of a vehicle, wherein at least one cylinder is operated with at least partial combustion with auto-ignition, and during a gear change, when the engine temporarily experiences a low load and low speed, the engine load is increased via the torque device so that this cylinder can continue to operate with at least partial combustion with auto-ignition.

[0006] In one example, a method may include the selective deactivation of one or more engine cylinders via deactivatable fuel injectors during a selected condition; and during cylinder deactivation, the injection of water into the one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst.

[0007] Events during which one or more cylinders can be deactivated include, for example, transmission shifting during automatic and manual operations, fuel cut-off during deceleration (DFSO), misfire failure effect management (MFEM), and engine speed revving control during start / stop transitions. In this way, by injecting water and reducing catalyst oxidation during a cylinder deactivation event, a fuel disadvantage caused by enrichment during cylinder reactivation can be mitigated while maintaining a required NOx emission level. Furthermore, water injection during a cylinder deactivation event can reduce the excessive increase in catalyst temperature. By lowering the catalyst temperature, optimal catalyst performance can be achieved.Furthermore, injecting water into the deactivated cylinders facilitates the reduction of hydrocarbons in the exhaust gas through a steam reforming process above the first exhaust catalyst during fuel reactivation. Therefore, in addition to reducing oxidation and the temperature of the exhaust catalyst, water injection can also lower hydrocarbon emissions.

[0008] Naturally, the above summary is intended to introduce, in simplified form, a selection of concepts that are further described in the detailed description. It is not intended to identify any key or essential features of the claimed subject matter, the scope of protection of which is defined solely by the claims that follow the detailed description.

[0009] In particular, power machine methods according to the invention are provided with the features of independent claims 1, 10 and 15.

[0010] Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages specified above or in any part of this disclosure. Fig. Figure 1 shows an example vehicle powertrain. Fig. Figure 2 shows a partial view of an internal combustion engine. Fig. Figure 3 shows a schematic representation of a closed crankcase ventilation system and a fuel tank rinsing system coupled to a power engine system. Fig. 4A, Fig. 4B and Fig. 4C shows example procedures for injecting water and adjusting the exhaust catalyst regeneration based on engine cylinder deactivation and exhaust catalyst temperature. Fig. Figure 5 shows an example procedure for adjusting the water injection during engine cylinder deactivation. Fig. Figure 6 shows an example of adjusting the water injection and the combustion air / fuel ratio in response to selective cylinder deactivation and the exhaust catalyst temperature.

[0011] The following description refers to systems and methods for injecting water during an engine cylinder deactivation event to reduce the exhaust catalyst regeneration requirement and control the excessive increase in exhaust catalyst temperature following cylinder deactivation. The cylinder deactivation event (or lean operation) can affect operations such as transmission shifting, deceleration fuel shutdown (DFSO), cylinder misfire failure effect management (misfire FMEM), and engine speed rev control during start / stop operations in the engine system located in Fig. 1, Fig. 2 and Fig. As shown in section 3, a power machine control unit can be configured to run a control routine such as the example routine from Fig. 4. To perform water injection and adjustment of the exhaust catalyst regeneration. In particular, water can be injected into one or more deactivated engine cylinders during the cylinder deactivation event based on the duration of the engine cylinder deactivation and the exhaust catalyst temperature. A method for determining the quantity and timing of water injection is described in Fig. Figure 5 illustrates this. When the engine cylinders are reactivated, the engine control unit can adjust the air-fuel ratio of the reactivated cylinders. Example settings for water injection and the air-fuel ratio in response to cylinder deactivation and exhaust catalyst temperature are shown in Figure 5. Fig. Figure 6 shows that the degree of richness (e.g., the degree of richness) of the combustion air / fuel ratio can be based on the amount of ammonia stored in an exhaust catalyst, such as an SCR catalyst. In this way, an exhaust catalyst, such as a three-way catalyst, can be regenerated while reducing the fuel disadvantage for the engine. Furthermore, by implementing water injection, the exhaust catalyst temperature can be controlled, thus preventing catalyst degradation.

[0012] With reference to Fig. Figure 1 shows a vehicle powertrain 100. The powertrain includes an internal combustion engine 10. In the example shown, the engine 10 can be selectively deactivated in response to transmission shifts, DFSO, cylinder misfires, and start / stop operations, as further described here with special reference to Fig. The engine 10 is shown coupled to a torque converter 11 via a crankshaft 40, as described in Figures 2-5. The engine 10 may include a starter system 9 to assist engine starting during engine restarts. The torque converter 11 is also coupled to a transmission 15 via a turbine wheel shaft 17. In one example, the transmission 15 is a stepped-ratio transmission. The transmission 15 may further include various gears and transmission clutches to adjust the torque output from the transmission to the wheels 19. The torque converter 11 has a lock-up clutch (not shown) that can be engaged, disengaged, or partially engaged. When the clutch is either disengaged or being disengaged, the torque converter is said to be in a disengaged state. The turbine wheel shaft 17 is also known as the transmission input shaft.

[0013] In one embodiment, the transmission 15 comprises an electronically controlled transmission with several selectable discrete gear ratios. The transmission 15 can also include various other gears, such as an axle ratio (not shown). Alternatively, the transmission 15 can be a continuously variable transmission (CVT). In another embodiment, the transmission 15 can be a manual transmission, in which case the drivetrain can include a clutch (instead of the torque converter as in an automatic transmission) that couples the engine to the transmission. Gear changes in a manual transmission can be controlled by a driver by disengaging and engaging the clutch via a clutch pedal to change gears.

[0014] The transmission 15 can further be coupled to the wheel 19 via an axle 21. The wheel 19 couples the vehicle (not shown) to the road 23. It should be noted that in one exemplary embodiment, this powertrain is coupled to a passenger car traveling on the road. Although various vehicle configurations can be used, in one example the power unit is the sole source of propulsion, and consequently the vehicle is not a hybrid electric vehicle, plug-in hybrid vehicle, etc. In other embodiments, the method can be incorporated into a hybrid vehicle.

[0015] A power engine control unit 42 can be configured to receive inputs from the power engine 10 and accordingly control an output torque of the power engine and / or the operation of the torque converter 11, the transmission 15, and the associated clutches. For example, output torque can be controlled by adjusting a combination of the ignition timing, fuel pulse width, fuel pulse timing, and / or air charge, by controlling the throttle opening and / or valve timing, valve lift, and boost pressure for turbocharged power engines. In the case of a diesel power engine, the control unit 42 can also control the power engine output torque by controlling a combination of the fuel pulse width, fuel pulse timing, and air charge.In all cases, the power machine control can be performed on a cylinder-by-cylinder basis to control the power machine output torque.

[0016] When cylinder deactivation conditions are met, the control unit 42 can selectively deactivate one or more cylinders by shutting off fuel injection and spark ignition for the engine cylinders. The deactivated cylinders can be kept in a deactivated state until cylinder reactivation conditions are confirmed. While the cylinders are in motion (not supplied with fuel), air can be pumped through the exhaust catalysts. This air can oxidize the catalysts, particularly a closely coupled three-way exhaust catalyst, reducing its ability to reduce exhaust NOx species and worsening exhaust emissions.

[0017] As in Fig. As detailed in sections 4-6, the engine control unit can also be configured with computer-readable commands to inject water into the engine cylinders during deactivation. The water and / or water vapor can then displace air from the engine cylinders, thereby reducing the intake of air at the deactivated cylinders. This can decrease the amount of air moving towards the catalysts and consequently reduce catalyst oxidation. After cylinder reactivation, the exhaust catalyst, such as a three-way catalyst, can then be regenerated by adjusting the combustion air / fuel ratio of the cylinders. In particular, the combustion air / fuel ratio can be reduced so that the air / fuel ratio has a rich tendency. The degree of richness can be based on the ammonia content stored in an exhaust catalyst, such as an SCR catalyst.For example, if the ammonia content of the exhaust catalyst is higher, the rich mixture may be lower. Injecting water during cylinder deactivation can allow the ammonia content of the exhaust catalyst to remain at a higher level than if water injection were not used. Conversely, a less rich mixture may be required during cylinder reactivation. This can reduce the fuel consumption disadvantage experienced during exhaust catalyst regeneration, thereby improving overall fuel economy while meeting NOx emission requirements.Furthermore, water injection into the deactivated cylinders can reduce hydrocarbon emissions through a steam reforming process above the exhaust catalyst during fuel reactivation with a rich air / fuel ratio. This process converts the hydrocarbons in the exhaust gas into CO and the associated hydrogen into H2. The CO and H2 can then be oxidized above the SCR catalyst, further reducing hydrocarbon emissions. Due to the endothermic nature of the steam reforming process, injecting water into the deactivated cylinders can also reduce the increase in exhaust catalyst temperature, thus preventing catalyst degradation.

[0018] In one example, the SCR catalyst may contain copper. In another example, the SCR catalyst may be a copper / zeolite or a modified copper / zeolite SCR catalyst.

[0019] Fig. Figure 2 is a schematic diagram 200 showing a cylinder of a multi-cylinder engine 210, which may be included in a motor vehicle's drive system. The engine 210 can be controlled, at least partially, by a control system with a control unit 12 and by input from a vehicle driver 132 via an input device. In one example, the input device includes an accelerator pedal 130 and a pedal position sensor 134 for generating a proportional pedal position signal PP.

[0020] A combustion chamber 30 of the engine 210 can comprise cylinder walls 32, in which a piston 36 is arranged. The piston 36 can be coupled to a crankshaft 40, so that a reciprocating motion of the piston is converted into a rotary motion of the crankshaft. The crankshaft 40 can be coupled to at least one drive wheel of a vehicle via an intermediate gear system. Furthermore, a starter motor can be coupled to the crankshaft 40 via a flywheel to enable the engine 210 to be started.

[0021] The combustion chamber 30 can receive intake air from an intake manifold 144 via an intake passage 142 and can expel combustion gases via an exhaust passage 148. The intake manifold 144 and the exhaust passage 148 can be selectively connected to the combustion chamber 30 via a respective intake valve 52 and exhaust valve 54. In some embodiments, the combustion chamber 30 can include two or more intake valves and / or two or more exhaust valves. An exhaust camshaft 53 actuates the exhaust valve 54 according to the profile of a cam arranged along the length of the exhaust camshaft. An intake camshaft 51 actuates the intake valve 52 according to the profile of a cam arranged along the length of the camshaft. An exhaust cam position sensor 57 and an intake cam position sensor 155 transmit respective camshaft positions to the control unit 12.

[0022] A fuel injector 66 is directly coupled to the combustion chamber 30 for injecting fuel directly into it in relation to the pulse width of a signal FPW received by the control unit 12 via an electronic driver 68. In this way, the fuel injector 66 performs what is known as direct injection of fuel into the combustion chamber 30. The fuel injector can be located, for example, on the side or top of the combustion chamber. Fuel can be supplied to the fuel injector 66 by a fuel system (not shown) comprising a fuel tank, a fuel pump, and a fuel distribution line.In some embodiments, the combustion chamber 30 may alternatively or additionally include a fuel injector located in the intake manifold 144 in a configuration that creates what is known as port fuel injection into the intake port upstream of the combustion chamber 30. The intake passage 142 may include a throttle valve 62 with a throttle plate 64. In this particular example, the position of the throttle plate 64 can be changed by the control unit 12 via a signal supplied to an electric motor or actuator included with the throttle valve 62, a configuration commonly referred to as electronic throttle control (ETC). In this way, the throttle valve 62 can be actuated to modify the intake air supplied to the combustion chamber 30 below other engine cylinders.The position of the throttle plate 64 can be supplied to the control unit 12 via a throttle valve position signal TP. The intake passage 142 can include an air mass sensor 120 and a manifold air pressure sensor 122 for supplying the respective signals MAF and MAP to the control unit 12.

[0023] An ignition system 88 can supply an ignition spark to the combustion chamber 30 via a spark plug 92 in response to a pre-ignition signal SA from the control unit 12 under selected operating modes. Although spark ignition components are shown, in some embodiments the combustion chamber 30 or one or more other combustion chambers of the engine 10 can be operated in a compression ignition mode with or without a spark.

[0024] The engine 210 may include a water injection system for injecting water into deactivated cylinders. The water injection system may include a water injection nozzle for each cylinder for injecting water or windshield washer fluid. In one example, a channel water injection nozzle 94 may be located inside the intake manifold 144 on an intake port and / or near the intake valve 52. In another example, a direct water injection nozzle (not shown) may be located inside the combustion chamber 30. In this example, the direct water injection nozzle can inject water directly into the engine cylinder. In yet another example, a second channel water injection nozzle (not shown) may be located inside the exhaust passage 148 downstream of the exhaust valve 54.

[0025] Injecting water into the deactivated engine cylinders can reduce the amount of air moving through the cylinders to the exhaust manifold and catalytic converters. For example, if the water injection system used in engine 210 is the 94 channel water injection system, a channel water injector nozzle can inject water into the intake port, at the intake valve of the deactivated cylinder. In one example, the water injection via the channel water injection system can occur during cylinder deactivation, before the intake valve opens (e.g., while the intake valve is closed). The injected water can vaporize at and / or around the intake valve. The injected water and / or water vapor can then displace intake air surrounding the intake port.When the intake valve opens, the water and / or water vapor can displace the intake air, thus reducing the amount of intake air entering the cylinder. When the exhaust valve of the non-firing (e.g., deactivated) cylinder opens, the water vapor itself can move through the exhaust system and towards the catalytic converters. Any air flowing through the exhaust system can be diluted with the water. Furthermore, the amount of oxygen flowing through the exhaust system can be reduced by the water vapor, thereby reducing the oxidation of the catalytic converters.

[0026] An engine control unit can actuate the water injectors of the corresponding deactivated cylinders to inject water during cylinder deactivation. The control unit can manage the timing, duration, and quantity of water injection. In response to the deactivation of one or more engine cylinders, the control unit can actuate the water injectors to inject a quantity of water into the intake port, engine cylinder, or exhaust manifold. In one embodiment, the control unit can actuate channel water injectors to inject water before the intake valve opens. In another embodiment, the control unit can actuate direct water injectors to inject water just before the intake valve opens, near top dead center in the combustion stroke.In this embodiment, however, the water may not have enough time to expand and displace the air. Therefore, by injecting the water near top dead center during the combustion stroke, the heat in the combustion chamber can more effectively vaporize the injected water. In yet another embodiment, the control unit can actuate channel water injection nozzles in the exhaust manifolds to inject water into the exhaust manifold corresponding to the deactivated cylinder bank before the exhaust valve opens. The control unit can then stop the water injection when cylinder reactivation conditions are met.

[0027] The control unit can also control the amount of water injected into the deactivated cylinders at one time. See below for further details. Fig. As discussed in section 5, the amount of injected water can be based on the volume of the engine cylinder. In particular, the amount of water injected at the intake port or directly into the engine cylinder can correspond to the amount of water that can essentially fill the cylinder with water vapor. In itself, this amount of water vapor can reduce the space available for air to enter the cylinder and reach the exhaust system and catalytic converters. The volume of water vapor formed by a given amount of injected water can increase with increasing temperature. Consequently, the amount of water injected at the deactivated cylinders can be based on an engine cylinder volume and an intake port and / or intake manifold temperature. The amount of injected water can further depend on additional engine operating conditions, such as…Manifold pressure, MAP (manifold absolute pressure), estimated piston valve and piston head temperatures, and / or engine speed are used as the basis for the amount of injected water. Furthermore, the amount of water injected can be based on a reading from an exhaust gas oxygen sensor.

[0028] In this way, injecting water into the deactivated cylinders can reduce the amount of air entering the combustion chamber and subsequently the exhaust manifold, thus lowering the oxygen concentration reaching the exhaust catalyst. This, in turn, reduces the extent of catalyst reduction and the amount of catalyst regeneration required after reactivating the cylinders. The injected water can also displace the intake air and reduce the amount of oxygen flowing through the deactivated cylinders and into the exhaust manifold. Furthermore, water and / or water vapor moving through the exhaust system can react with hydrocarbons above the first exhaust catalyst in a vapor reforming reaction, forming CO and H₂. H₂ can then reduce NO above the catalyst, forming ammonia (NH₃).Furthermore, it is noted that the CO and H2 formed do not react strongly with ammonia in a secondary exhaust catalyst (such as an SCR catalyst) and can be oxidized by residual O2 above the secondary catalyst. Once the engine cylinders are reactivated, the engine control unit can then set a combustion air / fuel ratio during cylinder reactivation based on the amount of ammonia stored in the SCR catalyst at the time of reactivation. For example, the cylinders can be reactivated with a combustion air / fuel ratio that is richer than stoichiometric. If the amount of ammonia in the SCR catalyst at cylinder reactivation is below a threshold level, the richer combustion air / fuel ratio can exhibit a higher rich tendency.However, if the amount of ammonia in the SCR catalyst is greater than the threshold level for cylinder reactivation, the richer air / fuel ratio may exhibit a less pronounced richness. The rich air / fuel mixture can be burned for a period of time to regenerate the three-way catalyst (e.g., the closely coupled catalyst). In this way, the regeneration requirements for the closely coupled catalyst can be reduced depending on the amount of ammonia stored in the SCR catalyst.

[0029] Injecting water into the deactivated engine cylinders during cylinder deactivation reduces the amount of oxygen entering the exhaust system, thereby decreasing the oxidation of the primary exhaust catalyst (e.g., a three-way catalytic converter). Furthermore, water injection into the deactivated cylinders can reduce hydrocarbon emissions due to steam reforming over the primary exhaust catalyst and the subsequent oxidation of H₂ and CO over a secondary exhaust catalyst (e.g., an SCR catalyst). Consequently, the increase in exhaust catalyst temperature can be reduced. Additionally, water can increase ammonia formation at a secondary exhaust catalyst (e.g., an SCR catalyst), thus increasing the amount of ammonia available during cylinder reactivation.In principle, injecting water can reduce the amount of rich mixture required after reactivating the engine cylinders, thereby reducing the fuel disadvantage suffered during the regeneration of the first catalyst.

[0030] It should be noted that various conditions exist under which one or more cylinders can be deactivated. In some cases, fewer than all engine cylinders (e.g., fuel injection deactivated) may be deactivated during an engine cycle, and only one may be deactivated for a single engine cycle. In one embodiment, a number of sequentially firing cylinders may be deactivated during engine start-up in a single engine cycle (e.g., only two sequential cylinders out of a total of six cylinders, or only three sequential cylinders out of a total of six cylinders). The number of cylinders deactivated in a single engine cycle may be based on a torque reduction requirement to reduce engine whine during engine restart from an idle stop, thereby mitigating the effect of a transmission that is at least partially engaged, such as a gearbox.The torque transmitted via a torque converter is reduced. Under these circumstances, water injection, as described here, can be applied to these deactivated cylinders.

[0031] In one embodiment, fuel injector deactivation during transmission shift events can be used to control engine torque and improve shift quality. Again, a selected number of specific cylinder fuel supply events can be skipped to rapidly reduce torque for a short duration (e.g., a single cylinder combustion event in an engine cycle). Under these circumstances, water injection, as described here, can be applied to each of the deactivated cylinders.

[0032] Other embodiments can utilize water injection, as further described here, such as other transmission events, a power engine start-up process, standard operation in response to component deterioration, and others.

[0033] Returning to Fig. Figure 1 shows an exhaust gas sensor 126 coupled to the outlet passage 148 upstream of an exhaust gas purification device 70. The sensor 126 can be any suitable sensor for providing an indication of the exhaust gas air / fuel ratio, such as a linear oxygen sensor or UEGO (universal or wideband exhaust gas oxygen sensor), a dual-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. The exhaust gas purification device 70 is shown arranged along the outlet passage 148 downstream of the exhaust gas sensor 126. The device 70 can be a three-way catalytic converter (TWC), a NOx trap, an SCR catalyst, various other exhaust gas purification devices, or combinations thereof. For example, an exhaust gas purification system of a vehicle may include one or more exhaust gas purification devices with at least one SCR catalyst and at least one three-way catalyst.These catalysts can be arranged in a different configuration within the exhaust aftertreatment system. In principle, the methods described below can be implemented in a variety of power engines with different exhaust aftertreatment system configurations. For example, the exhaust aftertreatment device 70 can include a first exhaust catalyst (such as a three-way catalyst) and a second exhaust catalyst (such as an SCR catalyst). Furthermore, the exhaust aftertreatment device 70 can include a temperature sensor (not shown) to provide an indication of the temperature of the first exhaust catalyst (i.e., the three-way catalyst).

[0034] The control unit 12 is in Fig. 2 as a microcomputer with a microprocessor unit 102, input / output ports 104, an electronic storage medium for executable programs and calibration values, shown in this particular example as a read-only memory 106, a direct access memory 108, a hold memory 110 and a data bus.The control unit 12 can receive various signals from sensors coupled to the engine 210, in addition to the signals discussed previously, including the measurement of the mass airflow (MAF) from the mass airflow sensor 120; the engine coolant temperature (ECT) from the temperature sensor 112, which is coupled to a cooling sleeve 114; a vehicle brake signal; a profile ignition pulse (PIP) signal from a Hall effect sensor 118 (or other type) coupled to the crankshaft 40; a throttle position (TP) signal from a throttle position sensor; an exhaust catalyst temperature signal from an exhaust catalyst temperature sensor (not shown); and a manifold absolute pressure (MAP) signal from the manifold pressure sensor 122. An engine speed (RPM) signal can be generated by the control unit 12 from the PIP signal.The manifold pressure signal (MAP) from a manifold pressure sensor can be used to provide an indication of the vacuum or pressure in the intake manifold. It should be noted that various combinations of the above sensors can be used, such as a MAF sensor without a MAP sensor, or vice versa. For example, sensor 118, which is also used as an engine speed sensor, can generate a predetermined number of equally spaced pulses with each revolution of the crankshaft.

[0035] The storage medium read-only memory 106 can be programmed with computer-readable data representing instructions that can be executed by the microprocessor unit 102 to perform the procedures described below, as well as other variants that are expected but not specifically listed.

[0036] The control unit 12 also receives signals from and supplies control signals to a transmission (not shown). Transmission signals can include, but are not limited to, transmission input and output speeds, signals for regulating transmission line pressure (e.g., the fluid pressure supplied to transmission clutches), and signals for controlling the pressure applied to clutches to actuate transmission gears.

[0037] As described above, shows Fig. 2 only one cylinder of a multi-cylinder engine and each cylinder can likewise include its own set of intake / exhaust valves, fuel injector, spark plug, etc.

[0038] If you Fig. Turning to 3, it shows a power machine system 300 such as the one in Fig. 2 described power engine systems with a closed crankcase ventilation system (PCV system) 350 and a fuel tank rinsing system 360.

[0039] The PCV system 350 can comprise a crankcase 306 enclosing a crankshaft 40, with an oil pan 302 located below the crankshaft. An oil filling port 304 can be arranged in the crankcase 306 so that oil can be supplied to the oil pan 302.

[0040] The power engine system 300 can further comprise a combustion chamber 30. The combustion chamber 30 can include combustion chamber walls 32, in which a piston 36 is arranged. The piston 36 can be coupled to the crankshaft 40, so that a reciprocating motion of the piston is converted into a rotary motion of the crankshaft. The combustion chamber 30 can receive intake air from the intake manifold 144, which is arranged downstream of the throttle valve 62.

[0041] A throttle valve 62 can be arranged in the engine intake to control the airflow entering the intake manifold 144. The intake air can enter the combustion chamber 30 via a cam-actuated intake valve system 51. Likewise, combusted exhaust gas can leave the combustion chamber 30 via a cam-actuated exhaust valve system 53. In an alternative embodiment, one or more of the intake valve system and the exhaust valve system can be electrically actuated.

[0042] Exhaust combustion gases leave the combustion chamber 30 via the exhaust passage 148. An exhaust gas sensor 126 can be arranged along the exhaust passage 148. The sensor 64 can be a suitable sensor for providing an indication of the exhaust gas-air / fuel ratio, such as a linear oxygen sensor or UEGO (universal or wideband exhaust gas oxygen sensor), a dual-state oxygen sensor or EGO, a HEGO (heated EGO), a NOx, HC, or CO sensor. The exhaust gas sensor 126 can be connected to the control unit 12.

[0043] In the example of Fig. 3 is a PCV system 350 coupled to the engine intake, allowing gases in the crankcase to be vented from the crankcase in a controlled manner. During conditions when the manifold pressure (MAP) is lower than the atmospheric pressure (BP), the crankcase ventilation system 350 draws air into the crankcase 306 via a breather or vent pipe 311. The crankcase vent pipe 311 can be coupled to the fresh air intake passage 142 upstream of the throttle valve 62.

[0044] The PCV system 350 also vents gases from the crankcase and into the intake manifold 42 via a line 309 (here also referred to as PCV line 309). It can be seen that, as used here, PCV flow refers to the flow of gases through line 309 from the crankcase to the intake manifold. Similarly, as used here, PCV backflow refers to the flow of gases through line 309 from the intake manifold to the crankcase. PCV backflow can occur when the intake manifold pressure is higher than the crankcase pressure. In some examples, the PCV system 350 may be equipped with a means to prevent PCV backflow.In other examples, the occurrence of PCV backflow may be irrelevant or even desirable; in these examples, the PCV system 350 may exclude a means of preventing PCV backflow or may advantageously use PCV backflow, for example, for generating a vacuum.

[0045] The gases in the crankcase 306 can consist of unburned fuel, unburned air, and fully or partially combusted gases. Lubricant mist may also be present. Various oil separators can be integrated into the crankcase ventilation system 350 to reduce the oil mist exiting the crankcase through the PCV system. For example, the PCV line 309 can include a unidirectional oil separator 308 that filters oil from vapors exiting the crankcase 306 before re-entering the intake manifold 144. Another oil separator 310 can be arranged in the line 311 to remove oil from the stream of gases exiting the crankcase during turbocharged operation. The PCV line 309 can also include a vacuum sensor (not shown) coupled to the PCV system.

[0046] The fuel system 360 comprises a fuel tank 330 coupled to a fuel pump (not shown) and a fuel vapor canister 318. During a fuel tank refueling event, fuel can be pumped into the vehicle from an external source through a refueling door 328. The fuel tank 330 can hold several fuel mixtures, including fuels with a range of alcohol concentrations, such as various gasoline-ethanol blends, including E10, E85, gasoline, etc., and combinations thereof. A fuel level sensor (not shown) located in the fuel tank 330 can provide a fuel level indication (“fuel level input”) to the control unit 12. It can be seen that the fuel system 360 can be a non-recirculating fuel system, a recirculating fuel system, or various other types of fuel system.Vapors generated in the fuel tank 20 can be directed to the fuel vapor canister 318 via the line 322 before being purged to the engine inlet 144.

[0047] The fuel vapor canister 318 can be filled with a suitable adsorbent for the temporary capture of fuel vapors (including vaporized hydrocarbons) generated during fuel tank refueling operations, as well as everyday vapors. In one example, the adsorbent used is activated carbon. When purging conditions are met, such as the canister being saturated, the vapors stored in the fuel vapor canister 318 can be purged to the engine inlet 144 by opening the canister purge valve 314. Although a single canister 318 is shown, it can be seen that the fuel system 360 can include any number of canisters. In one example, the canister purge valve 314 can be a solenoid valve, with the opening or closing of the valve being performed by actuating the canister purge solenoid.

[0048] The canister 318 includes a vent 317 for directing gases from the canister 318 to the atmosphere when fuel vapors are stored or captured from the fuel tank 330. The vent 317 can also allow fresh air to be drawn into the fuel vapor canister 318 when stored fuel vapors are purged to the engine inlet 144 via the purge line 312 and the purge valve 314. Although this example shows the vent 317 connected to fresh, unheated air, various modifications can also be used. The vent 317 can include a canister vent valve 316 to regulate the flow of air and vapors between the canister 318 and the atmosphere. The canister vent valve can also be used for diagnostic routines.When included, the vent valve can be opened during fuel vapor storage operations (for example, during fuel refueling and while the engine is not running) so that air stripped from the fuel vapor after passing through the canister can be expelled to the atmosphere. During purging operations (for example, during canister regeneration and while the engine is running), the vent valve can likewise be opened to allow a flow of fresh air to strip the fuel vapors stored in the canister. In one example, the canister vent valve 316 can be a solenoid valve, with the opening or closing of the valve being effected by actuating a canister vent solenoid. In particular, the canister vent valve can be opened and closed by actuating the canister vent solenoid.

[0049] Fuel vapors released from the canister 318, for example during a purge, can be routed via the purge line 312 into the engine intake manifold 144. The flow of vapors along the purge line 312 can be regulated by the canister purge valve 314, which is coupled between the fuel vapor canister and the engine intake. The quantity and rate of vapors released by the canister purge valve can be determined by the duty cycle of an associated canister purge valve solenoid (not shown). The duty cycle of the canister purge valve solenoid can be determined by the vehicle's powertrain control module (PCM), such as the control unit 12, in response to engine operating conditions, including, for example, engine speed-load conditions, air / fuel ratio, canister load, etc.By commanding the canister purge valve to close, the control unit can seal off the fuel vapor recovery system from the engine intake. An optional canister check valve (not shown) may be included in purge line 312 to prevent intake manifold pressure from forcing gases in the opposite direction to the purge flow. The check valve may be necessary if the canister purge valve control is not precisely timed or if the canister purge valve itself can be forced into the open position by high intake manifold pressure.

[0050] During certain engine conditions, such as DFSO, when one or more cylinders can be deactivated, the vacuum created in the intake manifold can cause an excess of unburned hydrocarbons from the PCV flow system and / or fuel tank scavenging system to flow into the deactivated cylinder and subsequently into the exhaust and aftertreatment systems. The increased load of unburned hydrocarbons can cause an increase in the exhaust catalyst temperature. Performing water injection into the deactivated cylinders during a DFSO event can reduce hydrocarbon emissions and control the increase in exhaust catalyst temperatures. With water injection, expanding water vapor can reduce the amount of hydrocarbons entering the deactivated cylinders by displacement.Furthermore, water vapor flowing through the exhaust facilitates a steam reforming process, during which some of the hydrocarbons in the exhaust gas can be converted into CO and H2 above the first exhaust catalyst. The CO and H2 thus formed can then be consumed by residual oxygen above a second exhaust catalyst, such as an SCR catalyst. Because the steam reforming process is endothermic, the exhaust catalyst temperature can also be reduced. Therefore, water injection can be performed in the deactivated cylinders to reduce unburned hydrocarbons from the PCV flow and / or evaporative emissions from the fuel tank purge line entering deactivated cylinders, and to reduce hydrocarbon emissions during a DFSO event.The water injection system can include adjusting the amount of water injected in a closed-loop manner based on an indication of the exhaust gas composition from exhaust gas sensor 126. By adjusting the amount of water injected, the amount of air entering the cylinder and exhaust can be controlled.

[0051] In this way, by adjusting the amount of water injection to the deactivated cylinders based on a reading from the exhaust gas sensor during DFSO events, the amount of unburned hydrocarbons entering deactivated cylinders can be reduced (as they are displaced by the expanding water vapor), allowing these hydrocarbons to flow to cylinders without water injection (where combustion takes place) or later to reactivated cylinders without water injection (where combustion takes place). Such a process can be carried out even when the throttle valve on the intake manifold is almost closed or closed, creating a manifold vacuum that would otherwise increase the vapors drawn into the manifold and routed through the deactivated cylinders to the exhaust.Furthermore, hydrocarbon emissions and the increase in exhaust catalyst temperature can be reduced (through the steam reforming process), as discussed above. Details regarding the adjustment of the water injection quantity during cylinder deactivation are given in [reference]. Fig. 5 further developed.

[0052] The systems of Fig. Figures 1-3 provide a power engine system comprising a power engine, an intake manifold, and a power engine cylinder. The power engine cylinder has an intake port with an intake valve and a deactivatable fuel injector. The power engine system further comprises a water injection system with a water injector located in the intake port upstream of the intake valve for injecting water at the intake valve, and an exhaust aftertreatment device with a first exhaust catalyst and a second exhaust catalyst. The power engine system also includes a control unit with computer-readable commands for selectively deactivating one or more power engine cylinders via deactivatable fuel injectors and injecting water at the one or more deactivated power engine cylinders during deactivation to reduce the oxidation of the first exhaust catalyst.After deactivation, the control unit can stop the water injection, reactivate the one or more deactivated engine cylinders, and adjust the combustion air / fuel ratio of the reactivated engine cylinders based on an ammonia content stored in the second exhaust catalyst.

[0053] In this way, one or more engine cylinders can be selectively deactivated via deactivatable fuel injectors. During cylinder deactivation, water can then be injected into the one or more deactivated engine cylinders to reduce the oxidation of a first exhaust catalyst. In one example, the injection of water into the one or more deactivated cylinders can involve port injection of water at a closed intake valve of the one or more deactivated engine cylinders before the intake valve opens. In another example, the injection of water into the one or more deactivated engine cylinders can involve direct injection of water into the one or more deactivated engine cylinders before an intake valve of the one or more deactivated engine cylinders opens.In yet another example, water can be injected at an exhaust manifold of one or more deactivated engine cylinders before an exhaust valve of one or more deactivated engine cylinders opens.

[0054] An engine control unit can adjust the amount of water injected during water injection based on the volume of one or more engine cylinders, the engine temperature, the engine speed, the manifold pressure, and the amount of exhaust oxygen. Furthermore, the engine control unit can estimate the ammonia concentration stored in a secondary exhaust catalyst after engine cylinder reactivation conditions are met. In response to the engine cylinder reactivation conditions being met, water injection can then be stopped, and the one or more deactivated engine cylinders can be reactivated. The process can further include adjusting the combustion air / fuel ratio of the reactivated engine cylinders based on the ammonia concentration stored in the secondary exhaust catalyst.The combustion air / fuel ratio can decrease with decreasing ammonia content.

[0055] In one example, selective deactivation of one or more engine cylinders could include deactivating one or more cylinders in response to a gear shift in an automatic transmission for transmission torque control. Alternatively, one or more cylinders could be deactivated in response to a gear shift in a manual transmission. In a second example, selective deactivation of one or more engine cylinders could include deactivating one or more engine cylinders in response to a deceleration fuel cut-off event. In a third example, selective deactivation of one or more cylinders could include deactivating one or more cylinders in response to cylinder misfire detection.In a fourth example, selective cylinder deactivation can involve disabling one or more engine cylinders during temporary start / stop operations to control engine revving. Furthermore, when one or more engine cylinders are deactivated, other engine cylinders can continue to burn. For example, a method for selective cylinder deactivation can involve disabling only some of the engine cylinders while the remaining engine cylinders continue to operate by maintaining fuel injection and combustion in the remaining active cylinders. Furthermore, various combinations of the above examples can occur together, and the operating procedure is applicable to each of the above examples and can be used in combination.

[0056] If one now Fig. Referring to section 4, method 400 describes an example routine for injecting water based on the duration of an engine cylinder activation and an exhaust catalyst temperature, and for adjusting the exhaust catalyst regeneration after cylinder deactivation. Specifically, the method involves injecting water into deactivated engine cylinders to reduce exhaust catalyst oxidation and lower the exhaust catalyst temperature. During subsequent cylinder reactivation, less exhaust catalyst regeneration may then be required, and exhaust catalyst degradation may be reduced. In one example, the exhaust catalyst may be a primary exhaust catalyst, such as a three-way catalyst.Engine cylinder deactivation can occur, for example, during operations including any transmission shift, DFSO, cylinder misfire FMEM, and start / stop applications, whenever cutting off the fuel supply may be advantageous. Depending on the type of operation, cylinder deactivation may occur for a relatively short, medium, or long duration. For example, engine cylinder deactivation resulting from a transmission shift in an automatic transmission may occur for a shorter duration (i.e., fewer engine cycles) than engine cylinder deactivation due to a DFSO event. An engine control unit, such as control unit 12, which is located in... Fig. As discussed in section 1, it may contain instructions for executing procedure 400.

[0057] In the case of 402, the procedure involves estimating and / or measuring vehicle and engine operating conditions. These may include, for example, MAP, air / fuel ratio (AFR), exhaust flow rate, exhaust temperature, vehicle speed, engine speed, state of charge of a system battery, ambient temperature and pressure, engine or manifold temperature, crankshaft speed, transmission speed, available fuels, fuel alcohol content, etc.

[0058] In the 404, the control unit can determine, based on estimated operating conditions, whether cylinder deactivation conditions have been met. For example, a cylinder deactivation condition might be a transmission shift operation, which involves upshifting from a higher gear ratio to a lower gear ratio. During the transmission shift, one or more engine cylinders may be deactivated to reduce engine torque and, consequently, the engine speed to a desired speed for the upcoming gear change. Transmission shift conditions can be determined based on engine speed, engine torque, vehicle speed, accelerator pedal position, throttle valve position, gear change state, and so on. In some examples, transmission shift conditions might include operations within an automatic transmission.In some other examples, gear shifting may involve operations in a manual transmission.

[0059] In a second example, a cylinder deactivation condition could be a deceleration fuel cut-off operation, which can be performed by shutting off the fuel supply to one or more engine cylinders during engine deceleration to improve fuel economy and limit vehicle speed. Deceleration fuel cut-off conditions can be determined based on accelerator pedal position, engine speed, brake application detection, vehicle speed, throttle valve position, and so on. In a third example, engine operating conditions could specify cylinder misfiring, which is identified, for example, based on a change in crankshaft speed. Misfiring cylinders can be deactivated to prevent unburned fuel from passing through the catalytic converter.In a fourth example, a cylinder deactivation condition can occur during temporary start / stop operations and can be based on an engine speed exceeding a rev-up threshold, the application / release of the brake pedal, etc. One or more cylinders can be deactivated to reduce initial torque during a start following start / stop events and to lessen the engine speed surge of the initial start-up.

[0060] In an alternative embodiment, it can be determined whether a shutdown request has been received from the vehicle driver. For example, a shutdown request from the vehicle driver can be acknowledged in response to the vehicle ignition being moved to the off position. If a shutdown request from the driver is received, the engine can also be deactivated by cutting off the fuel supply and / or ignition spark to the engine cylinders, and the engine can coast to a standstill.

[0061] If any of the cylinder deactivation conditions in 404 are not met, the routine may end with the engine running while all cylinders are activated and firing.

[0062] However, if any or all of the engine deactivation conditions are met, the control unit at 408 can estimate the number of available water injection cycles based on the cylinder deactivation conditions. The number of water injection cycles can be based on the estimated duration of cylinder deactivation. For example, if the cylinders are deactivated during a transmission shift operation, the duration the cylinders remain deactivated may be less than the cylinder deactivation duration during a DFSO operation. Consequently, the number of water injection cycles during a transmission shift event may be less than the number of water injection cycles during a DFSO event.

[0063] When estimating the number of available water injection cycles, the control unit can determine at 410 whether the number of water injection cycles is greater than a threshold. If so, the control unit can deactivate the requested cylinders and prepare the deactivated cylinders for water injection at 416. For example, if the estimated number of available water injection cycles during a DFSO operation is greater than a threshold number of cycles, the control unit can perform an automatic DFSO operation, selectively deactivating the engine and preparing the system for water injection. Engine deactivation can include shutting off fuel injection and / or spark ignition for the engine. For example, selectively deactivatable fuel injectors for selected cylinders can be deactivated, and spark ignition for the selected cylinders can be interrupted.Preparation for water injection can include determining the timing and quantity of water injection. Additional details of water injection are provided in [reference to be inserted here]. Fig. 5 elaborated.

[0064] Following cylinder deactivation, the next step in procedure 418 involves injecting water via water injectors into the deactivated cylinders during the deactivation process. This may involve injecting water into deactivated cylinders using direct water injection or channel water injection at the intake port and intake valve, or at the exhaust manifold. Details regarding determining the amount of water injected and adjusting the water injection during cylinder deactivation are described in [reference to relevant document]. Fig. 5 shown.

[0065] At 420, the procedure next involves determining whether cylinder reactivation conditions have been met. During transmission shifting, cylinder reactivation may be determined based on the completion of a transmission upshift (e.g., completion of a gear shift from a higher ratio to a lower ratio). During deceleration fuel cut-off, a cylinder reactivation condition may be based on brake release, accelerator pedal position, throttle valve position, engine speed, and vehicle speed. Cylinder reactivation conditions for a misfiring cylinder may be based on the completion of the cylinder repair to correct the misfire. During transient start / stop operations, cylinder reactivation conditions may be based on brake pedal release, driver-requested torque, engine speed, and so on.

[0066] If cylinder reactivation conditions are not met, then engine operation can be maintained at 422 with one or more engine cylinders selectively deactivated by water injection.

[0067] If, on the other hand, the cylinder reactivation conditions are met at 420, the process continues with the procedure in Fig. 4C proceeds to estimate the stored ammonia content of a secondary exhaust catalyst. In one example, the secondary exhaust catalyst may be an SCR catalyst. The amount of ammonia stored at the secondary catalyst can depend on various factors that contribute to ammonia production and storage at the catalyst, as well as various factors that contribute to ammonia being removed from the secondary exhaust catalyst (e.g., consumed or discharged). These include, for example, the temperature, flow rate, and air / fuel ratio of the exhaust gas flowing through the secondary catalyst. The secondary catalyst ammonia content can further depend on the type of lean event, the duration of the lean event, the time since the last lean event, the feed gas NOx mass (FG NOx mass), and engine operating conditions such as the air / fuel ratio during non-lean events.

[0068] Returning to step 410, if the number of water injection cycles is not greater than the threshold, the routine continues to step 412, where the exhaust catalyst temperature can be determined. The exhaust catalyst can be a primary catalyst. The primary catalyst can be a three-way catalyst. At step 414, it can next be determined whether the temperature of the primary catalyst is greater than a threshold. If so, the control unit executes the routine at step 416, which involves deactivating the cylinders and preparing for water injection. Under such conditions, where the exhaust catalyst temperature is greater than the threshold, it can be advantageous to perform cylinder deactivation with water injection to reduce the catalyst temperature and thereby decrease catalyst degradation.However, if the exhaust catalyst temperature is found to be lower than the threshold temperature at 414, the routine can perform cylinder deactivation at 424 without water injection.

[0069] From 424, the routine can proceed to 428, where it can be determined whether cylinder reactivation conditions have been met, as described above. If cylinder reactivation conditions have been met, then the control unit can continue the procedure in Fig. Perform 4B.

[0070] Continued with Fig. 4B and Fig. At 430 and 440 respectively, the control unit can determine whether an estimated ammonia concentration in the second exhaust catalyst exceeds a threshold level. This threshold level indicates the required regeneration of the first exhaust catalyst. For example, if the ammonia concentration in the second exhaust catalyst increases, less regeneration of the first exhaust catalyst may be necessary. Reactivating the engine cylinders can include resuming spark ignition and reactivating the cylinder fuel injectors. Additionally, the fuel supply to the cylinders can be adjusted to create a richer or richer exhaust-air / fuel mixture, with the richer or richer mixture being determined by the ammonia concentration in the second exhaust catalyst relative to the threshold level.In one example, a higher or lower richness tendency can be set based on the amount of water injected during water injection into the deactivated cylinders to take advantage of the enhanced hydrocarbon reaction via the steam reforming process, as explained above.

[0071] If the ammonia content of the second exhaust catalyst is at 432 (or at 442 in Fig. 4C) is greater than the threshold level, the control unit itself can deactivate the cylinders at 434 (or at 444 in Fig. 4C) reactivate with a combustion air / fuel ratio exhibiting a lower rich tendency. In some examples, this may involve an air / fuel ratio slightly lower than the stoichiometric ratio. In one example, this may involve an air / fuel ratio at stoichiometry. For instance, if no regeneration of the first exhaust catalyst is required, the cylinder can be reactivated and operated at stoichiometry. The extent of a lower rich tendency may, in itself, decrease with increasing ammonia content of the second exhaust catalyst and decreasing required regeneration of the first exhaust catalyst. Fig. 4C further includes the procedure in 444 of stopping the water injection to the cylinders when one or more deactivated engine cylinders are reactivated.

[0072] If the ammonia content of the second exhaust catalyst is not greater than the threshold level, the procedure alternatively proceeds to 436 (or to 446 in Fig. 4C) continued. At 436 (or at 446 in Fig. 4C) The control unit can reactivate the engine cylinders with a combustion air / fuel ratio that tends to run richer. This is generally the case at 436 (or at 446 in Fig. 4C) uses a richer combustion air / fuel ratio than that used in 434 (or in 444 in Fig. 4C) used combustion air / fuel ratio. In Fig. 4C further includes in procedure 446 stopping the water injection when the deactivated cylinders are reactivated. In this way, the combustion air / fuel ratio of the reactivated cylinders can be richer if the ammonia content of the second exhaust catalyst is lower.

[0073] In one example, the adjustment of the combustion air / fuel ratio of the reactivated engine cylinders can be carried out for a certain period based on the estimated ammonia content of the second exhaust catalyst and the exhaust aftertreatment system configuration. In principle, after this period, the combustion air / fuel ratio of the reactivated cylinders can return to stoichiometry. If, for example, the estimated ammonia content at 430 (or at 440) increases, the duration of combustion at the richer air / fuel ratio may decrease.

[0074] In one example, the degree of richness during reactivation can be adjusted based on the amount of water injected into the deactivated cylinders during cylinder deactivation. Depending on the amount of injected water, for instance, more or fewer hydrocarbons can be converted during the steam reforming process above the first exhaust catalyst during reactivation. Consequently, the impact of hydrocarbons on the exhaust catalyst can be reduced by appropriately controlling the richness during reactivation. Therefore, the regeneration requirement for the first exhaust catalyst can vary depending on the amount of injected water. For example, with an increasing amount of water injection, the regeneration requirement for the exhaust catalyst can decrease. The duration or the richness of the richness can also be reduced.

[0075] After waiting for the predetermined duration, at 438 (or at 448 in Fig. 4C) the air / fuel ratio can be reduced to stoichiometry. In one example, the combustion air / fuel ratio of the reactivated cylinders can be increased from the set or richer air / fuel ratio (with a higher or lower rich tendency) to the stoichiometric ratio. Alternatively, the control unit can be set at 438 (or at 448 in Fig. 4C) continue to monitor the ammonia content of the second exhaust catalyst. If the ammonia content is higher than a second threshold level, the control unit can stop adjusting the air / fuel ratio of the reactivated cylinders and return the air / fuel ratio to stoichiometry. The second threshold level can be a level indicating that the first exhaust catalyst has regenerated.

[0076] As described in procedure 400 for 418, water can be injected using a water injection system during cylinder deactivation.

[0077] Fig. 5 describes a method 500 for adjusting water injection during cylinder deactivation. In particular, the engine control unit, such as control unit 12, can actuate water injection nozzles of corresponding deactivated cylinders to inject water during cylinder deactivation. The control unit can control the timing, duration, and quantity of the water injection.

[0078] In particular, in response to the deactivation of one or more engine cylinders at 416 in method 400, the control unit can actuate water injection nozzles to inject a quantity of water into one of the intake ports, engine cylinders, or exhaust manifolds. The location of the water injection can be based on the engine's water injection system. For example, an engine can include a direct water injection system with water injection nozzles located in each engine cylinder for directly injecting water into the cylinder. In another example, the engine can include a channel water injection system with water injection nozzles located in an intake port of each cylinder upstream of an intake valve for injecting water at or near the intake valve.In yet another example, the power engine may include a different canal water injection system with water injection nozzles arranged in one or more exhaust manifolds for injecting water into the exhaust manifolds.

[0079] In 502, the method can include determining the injection timing of water injection based on the injector position. For example, water injection can occur before the intake valve opens if the water injectors are located in the intake port of the cylinder. In another example, water injection can also occur before the intake valve opens if the water injectors are direct water injectors located in the engine cylinder. In yet another example, water injection can occur before the exhaust valve opens if the water injectors are channel water injectors located in one or more exhaust manifolds.

[0080] With the 504, the control unit can then determine the amount of injected water for each water injection event during cylinder deactivation (e.g., a water injection event can occur for each intake / exhaust cycle of the engine). The amount of injected water can be based on the volume of the engine cylinder. In particular, the amount of water injected at the intake port or directly into the engine cylinder can correspond to the amount of water that can substantially fill the cylinder with water and / or water vapor. This amount of water and / or water vapor can, in itself, reduce the available space for air to enter the cylinder and reach the exhaust system and catalytic converters. The volume of water vapor formed by a given amount of injected water can increase with increasing temperature.Consequently, the amount of water injected into the deactivated cylinders can be based on the engine cylinder volume and the intake manifold temperature (or engine temperature). The amount of injected water can further be based on additional engine operating conditions such as manifold pressure, MAP (manifold absolute pressure), estimated piston valve and piston head temperatures, and / or engine speed.

[0081] In some embodiments, the control unit can also adjust the valve timing of the intake and exhaust valves during cylinder deactivation and water injection. By delaying exhaust valve closure, for example, the intake and exhaust valves can open simultaneously (e.g., valve overlap). This can increase internal exhaust gas recirculation (EGR), thereby reducing the amount of fresh intake air entering the engine cylinder. Reducing the amount of intake air entering the cylinder can, in turn, decrease the amount of oxygen reaching the exhaust catalysts during cylinder deactivation. In some embodiments, increased valve overlap can be used in conjunction with water injection to reduce the overall amount of water injected during cylinder deactivation.In this embodiment, the method at 504 can include determining a valve timing setting to increase the internal EGR. The amount of water determined at 504 can then further be based on the amount of internal EGR generated by the set valve timing. In this way, a greater degree of valve overlap can result in a smaller amount of injected water for each water injection event.

[0082] Moving on to 506, the control unit can inject water into one or more selectively deactivated cylinders. Consequently, only the water injectors on the deactivated cylinder can inject water during cylinder deactivation. The procedure at 506 can involve injecting a specific amount of water at a specific time for the duration of the cylinder deactivation. At 508, the control unit can adjust the air-fuel ratio of the activated (e.g., firing) cylinders during selective cylinder deactivation. In one example, the control unit can adjust the air-fuel ratio of the activated cylinders to achieve a stoichiometric exhaust mixture. Alternatively, the control unit can adjust the air-fuel ratio of the activated cylinders to be slightly richer than stoichiometric.The air-fuel ratio of the activated cylinders can be based on the exhaust system configuration. However, since water injection can reduce oxidation of the exhaust catalyst, thus requiring less regeneration, the control unit can alternatively adjust the air-fuel ratio of the activated cylinders regardless of the exhaust system configuration to maintain stoichiometric exhaust gas.

[0083] The procedures at 506 and 508 can occur simultaneously and continuously during cylinder deactivation. At 510, water injection can continue until cylinder reactivation conditions are met. The procedure then reverts to 418 in procedure 400.

[0084] Fig. Figure 6 shows an example of the adjustment of water injection and combustion air / fuel ratio in response to selective cylinder deactivation and exhaust catalyst temperature. In particular, graph 600 shows changes between cylinder activation and cylinder deactivation shown in diagram 602. During the cylinder deactivation process, one or more engine cylinders can be selectively deactivated based on engine operating conditions by stopping fuel injection (e.g., fuel injector shut-off), while the other cylinders remain activated. Changes in the operation of a water injection system are shown in diagram 604. In particular, diagram 604 can represent a change from not injecting water to injecting water with the water injectors on the deactivated cylinders.Furthermore, graph 600 shows changes in gear shifting during vehicle operation in diagram 606, changes in exhaust catalyst temperature, such as that of a three-way catalyst (e.g., a first catalyst) in diagram 608, relative to a threshold temperature 616, changes in the air-fuel ratio (AFR) in diagram 610 relative to the stoichiometry 618, the ammonia content of an SCR catalyst (e.g., a second catalyst) in diagram 612 relative to a threshold level 620, and changes in the regeneration state of a three-way TWC catalyst (e.g., a first catalyst) in diagram 614 relative to a regenerated or threshold state 622. All changes are shown over time (along the x-axis).

[0085] Before t1, the engine may be operating with all engine cylinders active and essentially burning at stoichiometry 618 (Diagram 610). The water injectors may be switched off, so no water is injected into the engine cylinders (Diagram 604). If the engine is operating at stoichiometry, the ammonia content of the SCR catalyst may gradually increase (Diagram 612). The exhaust catalyst temperature may also gradually increase (Diagram 608), while remaining below the threshold temperature 616. Before t1, the ammonia content of the SCR catalyst may be higher than the threshold level 620, and the three-way catalytic converter (TWC) may be in a higher regeneration state (above the threshold state 622), meaning it may not require further regeneration.

[0086] At t1, due to a change in engine operating conditions (e.g., during a transmission shift, when the engine switches from a higher to a lower gear ratio), one or more engine cylinders can be selectively deactivated. The cylinders can be deactivated for a duration tx1, which may be less than the deactivation threshold. Consequently, the number of water injection cycles for the deactivated cylinders may be less than a threshold number of water injection cycles. Furthermore, at t1, the exhaust catalyst temperature may be lower than the threshold (Diagram 608). Consequently, because the deactivation duration at t1 is below a threshold and the catalyst temperature is lower than the threshold temperature, no water can be injected into the deactivated cylinders (Diagram 604).The air-fuel ratio of the active engine cylinders can be maintained essentially at stoichiometry (Diagram 610). By limiting water injection to the deactivated cylinders based on the duration of cylinder deactivation and the exhaust catalyst temperature, faster switching between cylinder deactivation and cylinder reactivation (during short deactivation conditions such as gear shifting) can be achieved. During cylinder deactivation (between t1 and t2), the TWC can undergo some oxidation, thereby reducing the TWC regeneration state (Diagram 614). Additionally, the ammonia content of the SCR catalyst can decrease.

[0087] At t2, in response to the fulfillment of cylinder reactivation conditions (Diagram 602), the engine operation can revert to activating the deactivated cylinders. In other words, at t2, deactivated cylinders can be reactivated upon completion of the transmission shift. To regenerate the TWC (Third-Central Water Concentration), the combustion air / fuel ratio (Diagram 610) can also be enriched for a duration d1 to raise the TWC regeneration state (Diagram 614) above the threshold state 622. The degree of richness of the fuel injection is adjusted based on the ammonia storage content (Diagram 612) of the SCR catalyst. Since the ammonia content is below the threshold level 620 during cylinder reactivation, a rich fuel injection with a higher richness tendency for a duration d1 is used to regenerate the TWC.During TWC regeneration, the ammonia stored in the SCR catalyst can be consumed to reduce exhaust NOx species, so that an exhaust NOx level is essentially maintained at the time of switching from cylinder deactivation to cylinder reactivation. However, if the cylinder continues to burn the richer air / fuel ratio, the ammonia content of the SCR catalyst can begin to increase before t3. At t3, the regeneration state of the TWC can be higher than the threshold, and consequently, the combustion air / fuel ratio of the reactivated cylinders can return to stoichiometry 618. Furthermore, between t2 and t3, the exhaust catalyst temperature (Diagram 608) can gradually increase while remaining below the threshold of 616.

[0088] At t4, a further change in engine operating conditions can occur, causing one or more engine cylinders to be selectively deactivated. For example, based on the driver releasing the accelerator pedal and applying the brakes, the control unit can command a deceleration fuel cut-off process at selected cylinders. The deceleration fuel cut-off can occur for a duration ty that is greater than the deactivation threshold. Consequently, in response to the cylinder deactivation duration exceeding a threshold, water can be injected through the water injectors at the deactivated engine cylinders (Diagram 604). Again, the combustion air / fuel ratio of the active cylinders can remain at stoichiometry 618 (Diagram 610).During cylinder deactivation between t4 and t5, the ammonia content of the SCR catalyst may decrease slightly but remain above threshold level 620 (Diagram 612), and the regeneration state of the TWC may also decrease but remain above or at threshold level 622 (Diagram 614). In principle, the NOx emission level can be maintained. Furthermore, by performing water injection on the deactivated cylinders, the temperature of the exhaust catalyst (608) can be kept below threshold level 616. These changes in the ammonia content of the SCR catalyst and the regeneration state of the TWC may be less than if no water injection were used during cylinder deactivation.

[0089] At t5, if cylinder reactivation conditions are met (such as completion of the deceleration fuel cut-off process), the engine control unit can reactivate the deactivated cylinders. Because the ammonia content of the SCR catalyst is greater than the threshold level of 620 at t5, the combustion air / fuel ratio of the reactivated cylinders can exhibit a less rich tendency. In the example shown in graph 600, the less rich tendency can be small, so the combustion air / fuel ratio of the reactivated cylinders is only slightly lower than stoichiometry 618. As shown from t4 to t5, water injection reduced the oxidation of the TWC and the reduction of ammonia. Consequently, a less rich tendency was required when the cylinders were reactivated, thus reducing the fuel disadvantage for the engine.If water injection had not been used between the T4 and T5, a richer fuel mixture would have been required in the T5 to regenerate the exhaust catalyst.

[0090] Between t5 and t6, the engine can continue to operate all cylinders. Because the combustion AFR is running lean, the ammonia content of the SCR catalyst can decrease to a threshold level, and the TWC regeneration state can also decrease to a state just below the threshold. Furthermore, the catalyst temperature can gradually increase while remaining below the threshold. Between t6 and t7, the engine can continue to operate all cylinders due to no change in engine operating conditions. The combustion AFR can be run rich to restore the TWC regeneration state to a state above the threshold. Consequently, the ammonia stored in the SCR catalyst can initially be consumed to reduce NOx species and may increase before t7.Between t6 and t7, if the engine continues to burn fuel, causing more exhaust gas to flow through the catalyst, the catalyst temperature can rise above the threshold temperature. At t7, a further change in the engine operating condition, such as a second gear shift in this example, can cause the control unit to deactivate one or more cylinders. The selected cylinders can be deactivated for a duration tx2 that is lower than the threshold. However, since the exhaust catalyst temperature at t7 is higher than the threshold temperature, even if the deactivation duration is shorter than the water injection threshold, water can be injected into deactivated cylinders to reduce the catalyst temperature below the threshold of 616.By injecting water into the deactivated cylinders, the catalyst temperature can be reduced, thus preventing catalyst degradation. This water injection can also reduce the ammonia concentration in the SCR and the regeneration status of the TWC. In other words, the ammonia concentration in the SCR catalyst can be kept above the threshold, and the TWC regeneration status can also be maintained at or above the threshold.

[0091] At t8, if cylinder reactivation conditions are met, water injection to the deactivated cylinders can be stopped and the deactivated cylinders can be activated. Furthermore, at t8, the catalyst temperature is below the threshold, the ammonia content of the SCR catalyst is above the threshold, and the regeneration status of the TWC is at the threshold. Between t8 and t9, the engine operates all cylinders with a combustion AFR at stoichiometry.

[0092] At t9, the engine operating conditions can next indicate a cylinder misfire. Upon detecting the misfire, the control unit can deactivate the misfiring cylinder. During the FMEM, the duration tz of the misfiring cylinder's deactivation can be estimated to be greater than the water injection threshold. Consequently, water can be injected into the deactivated cylinder. By injecting water into the misfiring cylinder, an excessive increase in catalyst temperature can be controlled, and excess air can be prevented from entering the exhaust and oxidizing the catalyst.

[0093] It can be seen that, although the example of Fig. Section 6, which discusses cylinder deactivation events such as transmission shifts, DFSO, and cylinder misfire, presents an alternative example: cylinder deactivation with water injection can be applied to start / stop transitions for engine speed rev control. Using water injection cylinder deactivation, the exhaust catalyst temperature can be controlled, and catalyst oxidation can be reduced. Consequently, catalyst degradation can be prevented, and emissions can be controlled. As a result, fuel economy can be improved.

[0094] In this way, one or more engine cylinders can be selectively deactivated via deactivatable fuel injectors. Water can then be injected into the one or more deactivated engine cylinders during deactivation. Injecting water can reduce the degree of oxidation of an exhaust catalyst, such as a three-way catalytic converter (TWC), and control an excessive increase in catalyst temperature. When the one or more deactivated engine cylinders are reactivated, the air-fuel ratio can be reduced or enriched to regenerate the three-way catalytic converter. However, less regeneration may be required due to the water injection during the deactivation event. The ammonia content of another exhaust catalyst, such as...An SCR catalyst can indicate how much regeneration is required and subsequently specify the required degree of richness of the combustion air / fuel ratio during cylinder reactivation.

[0095] As with t2 in Fig. As shown in Figure 6, during a first cylinder reactivation, if the ammonia content of an exhaust catalyst is lower than a threshold, a control unit can adjust the engine's air-fuel ratio to be richer than stoichiometry, with an initial, higher rich tendency. During a second cylinder reactivation, shown at t5, if the exhaust catalyst's ammonia content is higher than the threshold, the engine's air-fuel ratio is adjusted to be richer than stoichiometry, with a second, lower rich tendency. As shown between t2 and t3, during each of the first and second cylinder reactivations, the adjustment of the engine's air-fuel ratio based on the exhaust catalyst's ammonia content continues for a certain duration.In another example, the duration d1 can be shorter if the ammonia content of the SCR catalyst is greater than at t2. Fig. 6 shown.

[0096] As discussed above, injecting water into the one or more deactivated engine cylinders involves either injecting water into an intake port upstream of an intake valve of the one or more deactivated engine cylinders, injecting water directly into the one or more deactivated engine cylinders, or injecting water into an exhaust manifold of the one or more deactivated engine cylinders. The timing of the water injection can then be determined based on the position of the water injection.Furthermore, the amount of water injected during water injection can be determined based on one or more of the engine cylinder volume, engine temperature, engine speed, and manifold pressure, with the amount of injected water increasing with increasing cylinder volume and decreasing engine temperature.

[0097] Returning to Fig.As shown between t1 and t2 and between t4 and t5, during the selective deactivation of one or more engine cylinders, the fuel injection of active engine cylinders can be adjusted to maintain a stoichiometric air / fuel ratio. Alternatively, the fuel injection of the active engine cylinders can be adjusted to maintain an air / fuel ratio slightly richer than stoichiometric. Finally, as shown at t5 and t7, water injection can be stopped when the one or more deactivated cylinders are reactivated.

[0098] In this way, during an engine cylinder deactivation event, injecting water into the selectively deactivated engine cylinders can reduce the amount of oxygen that moves to the exhaust system and reaches a first and second exhaust catalyst. For example, in response to cylinder deactivation, one or more water injectors can inject water into an intake port of one or more deactivated engine cylinders. Upon reactivation of the engine cylinders, the combustion air / fuel ratio of the reactivated cylinders can then be adjusted based on the ammonia content of the second exhaust catalyst. In particular, a combustion air / fuel ratio with a lower rich tendency can be used to regenerate the first exhaust catalyst when the ammonia content exceeds a threshold level.Alternatively, a richer air / fuel ratio can be used to regenerate the first exhaust catalyst when the ammonia content of the second exhaust catalyst is below the threshold level. Water injection can help reduce the required extent of exhaust catalyst regeneration and can prevent an excessive increase in exhaust catalyst temperature. In this way, injecting water during engine cylinder deactivation can reduce the engine's fuel disadvantage and decrease catalyst degradation due to elevated catalyst temperatures, while also maintaining a required NOx level.

[0099] In one embodiment, an engine method may include the selective deactivation of one or more engine cylinders via deactivatable fuel injectors in response to an engine misfire in that one or more cylinders; and during cylinder deactivation, the injection of water into the one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst.

[0100] It should be noted that an integrated method can be created in one embodiment for performing water injection under any of several operating conditions. For example, one embodiment may include a method that comprises the following: During engine misfire conditions, selective deactivation of one or more engine cylinders via deactivatable fuel injectors in response to an engine misfire in that one or more engine cylinders; and during cylinder deactivation, injection of water into the one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst; During temporary transmission conditions, selective deactivation of one or more engine cylinders via deactivatable fuel injectors during a transmission event; and during cylinder deactivation, injection of water into the one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst; and During a stop / start engine restart from a standstill, selective deactivation of one or more engine cylinders via deactivatable fuel injectors is achieved; during an engine start-up from a standstill, water is injected into the one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst, with the amount of water injected under each of the conditions being based on the amount injected under the other conditions to avoid over-injection of water. In this way, water injection can be coordinated under multiple conditions.

[0101] It should be noted that the example control routines contained herein can be used with various power machine and / or vehicle system configurations. The specific routines described here can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multitasking, multithreading, and the like. In principle, various actions, operations, and / or functions shown in the sequence can be performed in parallel or, in some cases, omitted. Likewise, the order of processing is not necessarily required to achieve the features and benefits of the example implementations described here, but is provided for ease of explanation and description.One or more of the depicted actions or functions can be performed repeatedly, depending on the specific strategy used. Furthermore, the described actions can graphically represent code to be programmed into the computer-readable storage medium in the powertrain control system.

[0102] It is evident that the configurations and routines disclosed herein are essentially exemplary and that these specific embodiments should not be considered limiting, as numerous variations are possible. For example, the above technology can be applied to V-6, I-4, I-6, V-12, 4-boxer, and other types of power engines. Furthermore, one or more of the various system configurations can be used in combination with one or more of the described diagnostic routines. The subject matter of this disclosure includes all new and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or properties disclosed herein.

[0103] The following claims specifically indicate certain combinations and subcombinations that are considered novel and not obvious. These claims may refer to "one" element, "a first" element, or the equivalent thereof. Such claims should be understood as the comprehensive integration 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 properties may be claimed by amending the present claims or by filing new claims in this or a related application. Such claims, whether broader, narrower, the same, or different in scope compared to the original claims, shall also be considered to be included in the subject matter of the present disclosure.

Claims

[1] Power engine process comprising the following: Selective deactivation of one or more engine cylinders via deactivatable fuel injectors during a transmission event; and during cylinder deactivation, injection of water into the one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst, wherein, during cylinder deactivation, the injection of water into the one or more cylinders includes the injection of water into the one or more cylinders in response to a number of water injection cycles exceeding a threshold. [2] Method according to claim 1, wherein during cylinder deactivation, the injection of water at one or more cylinders comprises the injection of water at one or more cylinders in response to an exhaust catalyst temperature being greater than a threshold value. [3] Method according to claim 1, wherein the number of water injection cycles is based on an estimated duration of cylinder deactivation based on one or more engine operating conditions. [4] Method according to claim 1, wherein the transmission event comprises a transmission event in an automatic transmission. [5] Method according to claim 1, wherein the transmission event comprises a transmission event in a manual transmission. [6] Method according to claim 1, wherein the transmission event is a transmission shifting event comprising shifting from a higher transmission ratio to a lower transmission ratio. [7] The method of claim 1, further comprising adjusting the quantity of water injected during the injection of water based on one or more of the engine volume, engine temperature, engine speed and manifold pressure. [8] The method of claim 1, further comprising stopping the water injection in response to the reactivation of one or more deactivated engine cylinders. [9] The method of claim 1, further comprising adjusting the combustion air / fuel ratio of the reactivated engine cylinders on the basis of an ammonia content stored in a second exhaust catalyst, wherein the combustion air / fuel ratio decreases with decreasing ammonia content. [10] Power machine method comprising the following: Selective deactivation of one or more engine cylinders via deactivatable fuel injectors during an engine start-up from a standstill; and During cylinder deactivation, water is injected into one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst, wherein the injection of water into one or the multiple deactivated engine cylinders are based on a number of water injection cycles and are further based on an exhaust catalyst temperature. [11] Method according to claim 10, wherein the injection of water at the one or more deactivated engine cylinders comprises either the injection of water at an inlet port upstream of an inlet valve of the one or more deactivated engine cylinders, the injection of water directly into the one or more deactivated engine cylinders, or the injection of water at an outlet manifold of the one or more deactivated engine cylinders. [12] Method according to claim 10, wherein the selective deactivation takes place during a power engine restart of a stop / start power engine stop from standstill, wherein a torque converter is at least partially unlocked, and responds to a power engine speed during start-up that is greater than a threshold value. [13] Method according to claim 10, further comprising adjusting the injection timing of the water injection based on operating conditions. [14] The method of claim 10, further comprising stopping the injection of water when one or more deactivated cylinders are reactivated. [15] Power machine process comprising the following: Selective deactivation of one or more engine cylinders via deactivatable fuel injectors during a deceleration fuel cut-off; and During cylinder deactivation, water is injected into one or more deactivated engine cylinders to reduce the oxygenation of a first exhaust catalyst, wherein the injection of water into one or more deactivated cylinders is based on a number of water injection cycles and further on a temperature of the first exhaust catalyst. [16] The method of claim 15, further comprising adjusting the amount of water injected during water injection based on one or more of an engine volume, engine temperature, engine speed, manifold pressure and exhaust oxygen level, and adjusting a rich tendency during reactivation based on the amount of water injected. [17] The method of claim 15, further comprising stopping the water injection, reactivating one or more deactivated engine cylinders and adjusting a combustion air / fuel ratio of the reactivated engine cylinders based on an ammonia content stored in a second exhaust catalyst.

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