SUPERCHARGED ENGINE WITH VARIABLE VALVE OPERATION

Abstract

Machine process comprising: during a first condition, firing a subset of second cylinders each including a first exhaust port coupled to a turbocharger via a second exhaust manifold and a second exhaust port coupled to a catalyst and not to the turbocharger via a first exhaust manifold, and directing all exhaust gases from the subset of second cylinders through the first exhaust manifold, and during a second condition, firing all cylinders, namely the second cylinders and first cylinders including two exhaust ports coupled to the turbocharger via the second exhaust manifold, and directing a first portion of the exhaust gases through the second exhaust manifold and directing a second portion of the exhaust gases through the first exhaust manifold.

Description

REGIONThe present disclosure relates to a camshaft profile switching system in an engine.PRIOR ART AND SUMMARYSupercharging an engine allows the engine to supply power similar to that of a larger displacement engine while maintaining engine pumping work near the pumping work of a normally aspirated engine having a similar displacement. Therefore, the supercharging may extend the operating range of an engine. However, boosted engines may have difficulty achieving fast catalyst light-off times after an engine start. The additional mass and surface area introduced through the turbine housing may significantly reduce the catalyst inlet temperature. Previous solutions for achieving fast catalyst warm-up have used high heat flow combustion strategies and / or turbine bypass valves to increase the temperature of the exhaust gas reaching the catalyst.From the prior art, for example from the document US 2010 / 0 162 689 A1, engine systems are known which have a plurality of cylinders each with an inlet valve and a first and a second outlet valve, wherein half of the outlet valves open a direct connection to the catalytic converter while the other half opens a connection to the turbocharger. A similar system is known from the document DE 10 2011 077 205 A1.Fuel management systems and fuel methods, in particular for engines with variable displacement, are known from the document DE 10 2011 012 917 A1.However, the inventors have recognized some problems with such an approach. The combustion with high heat uses excessive fuel, which reduces fuel saving. Further, the use of turbine bypass valves may be complex and may place sealing and higher actuation force demands.Thus, in one example, some of the above issues may be at least partially addressed by an engine method including, during a first condition, igniting a subset of cylinders and directing all exhaust gases from the subset of cylinders through a first exhaust manifold directly coupled to a catalyst and not to a turbocharger, and, during a second condition, igniting all cylinders, directing a first portion of the exhaust gases through a second exhaust manifold coupled to the turbocharger and directing a second portion of the exhaust gases through the first exhaust manifold.In this way, during engine cold-start conditions, exhaust may be directed from the fired cylinders directly to the catalyst bypassing the turbine. The engine may be configured such that the exhaust opening surface area between the exhaust valves and the catalyst surface is reduced, for example, the engine may be an in-line four-cylinder engine having an exhaust opening of each of the inner cylinders directly coupled to the catalyst via the first exhaust manifold. During cold start operation, a camshaft profile may be adjusted such that only the exhaust ports coupled to the first exhaust manifold are opened. During the standard warmed up operation, all cylinders are fired and the camshaft profile is switched so that each exhaust port of each cylinder is opened, allowing a majority of the exhaust gases to be directed to the turbine.The above advantages and other advantages and features of the present specification will become apparent from the following detailed description, taken alone or in conjunction with the accompanying drawings.It is to be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not intended to identify key or essential features of the claimed subject matter, the scope of which is defined solely by the claims that follow the detailed description. Further, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 shows an exemplary machine pattern. FIG. 2 shows an example engine including a turbocharger and a cam profile switching system. FIG. 3 is a flow chart illustrating a method of operating an engine having a cam profile switching system. FIGS. 4-6 illustrate example exhaust valve controls according to embodiments of the present disclosure.DETAILED DESCRIPTIONIn boosted engines, the exhaust gases are typically directed through the turbocharger before reaching one or more downstream exhaust components, such as catalysts. Flowing through the turbocharger may cool the exhaust gases due to additional surface area and a longer exhaust path provided by the turbocharger, which reduces catalyst inlet temperature and increases catalyst light-off time during cold engine starts. To increase catalyst inlet temperature during cold start conditions, a cam profile switching system with a segmented integrated exhaust manifold and variable displacement engine (VDE) may be combined to provide a direct, shortened exhaust path to the catalyst. For example, in an in-line four-cylinder engine, the inner cylinders may each have an exhaust port directly coupled to the catalyst via separate exhaust manifolds and an exhaust port directly coupled to the turbocharger, while the outer cylinders may be coupled to the turbocharger only. During cold start conditions, a cam profile may be activated with only the exhaust valves controlling the ports directly coupled to the catalyst being opened while all remaining exhaust ports (e.g., the exhaust ports directly coupled to the turbocharger) being maintained closed. Further, during these conditions, the engine may be operated in VDE operation to deactivate the outer cylinders. In this way, the exhaust gases may be directed to the catalyst and not the turbocharger to quickly warm up the catalyst. FIGS. 1 and 2 depict an example engine including an integrated segmented exhaust manifold, systems for operating with cam profile switches and VDE, and a controller capable of executing the method of FIG. 3. Example exhaust valve controls during execution of the method of FIG. 3 are depicted in FIGS. 4-6.Referring specifically to FIG. 1, it includes a schematic diagram showing one cylinder of the multi-cylinder internal combustion engine 10. The engine 10 may be controlled at least in part by a control system including the controller 12 and by input from a vehicle driver 132 via an input device 130. In this example, the input device 130 includes an accelerator pedal and a pedal position sensor 134 to generate a proportional pedal position signal PP.The combustion cylinder 30 of the engine 10 may include combustion cylinder walls 32 with a piston 36 positioned therein. The piston 36 may be coupled to the crankshaft 40 such that reciprocating motion of the piston is converted to rotational motion of the crankshaft. The crankshaft 40 may be coupled to at least one drive wheel of a vehicle via an intermediate transmission system. Further, a starter motor may be coupled to crankshaft 40 via a flywheel to enable a starting operation of engine 10.The combustion cylinder 30 may receive intake air from the intake pipe 44 via the intake passage 42 and may exhaust combustion gases via the exhaust passage 48. The intake manifold 44 and the exhaust passage 48 may selectively communicate with the combustion cylinder 30 via a respective intake valve 52 and exhaust valve 54. In certain embodiments, combustion cylinder 30 may include two or more intake valves and / or two or more exhaust valves.In this example, intake valve 52 and exhaust valve 54 may be controlled by cam actuation via respective cam actuation systems 51 and 53. Cam actuation systems 51 and 53 may each include one or more cams and include one or more cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift systems (VVL) operated by controller 12 to vary valve operation. The position of intake valve 52 and exhaust valve 54 may be determined by position sensors 55 and 57, respectively, or via camshaft sensors. In alternative embodiments, intake valve 52 and / or exhaust valve 54 may be controlled by electric valve actuation. For example, cylinder 30 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation including CPS and / or VCT systems.The combustion cylinder 30 includes a fuel injector 66 arranged in the intake passage 42 in a configuration that provides what is known as port injection of fuel into the intake port upstream of the combustion cylinder 30. The fuel injector 66 injects fuel therein in proportion to the pulse width of the FPW signal received from the controller 12 via the electronic driver 68. Alternatively or additionally, in certain embodiments, the fuel injector may be installed, for example, on the side of the combustion cylinder or in the upper portion of the combustion cylinder to provide what is known as direct injection of fuel into the combustion cylinder 30. Fuel may be provided to fuel injector 66 by a fuel delivery system (not shown) including a fuel tank, a fuel pump, and a fuel rail.The intake passage 42 may include a throttle valve 62 having a throttle 64. In this particular example, the position of throttle 64 may be varied by controller 12 via a signal provided to an electric motor or actuator included in throttle valve 62, a configuration that may be called electronic throttle control (ETC). In this way, the throttle valve 62 may be operated to vary the intake air provided to the combustion cylinder 30 among other combustion cylinders. The intake passage 42 may include a mass air flow sensor 120 and an intake manifold air pressure sensor 122 for providing respective signals MAF and MAP to the controller 12.The ignition system 88 may provide spark to the combustion chamber 30 via a spark plug 92 in response to a pre-ignition signal SA from the controller 12 under selected operating modes. Although spark ignition components are shown, in certain embodiments, combustion chamber 30, or one or more other combustion chambers of engine 10, may be operated in a compression ignition mode with or without spark.Exhaust gas sensor 126 is shown with exhaust passage 48 upstream of catalyst 70. The sensor 126 may be any suitable sensor for providing an indication of exhaust gas air / fuel ratio, such as a linear oxygen sensor or a universal or wide range exhaust gas oxygen (UEGO), a bi-stable oxygen sensor or EGO, a heated EGO (HEGO), NO, HC, or CO sensor. The exhaust system may include light-off catalysts and underbody catalysts, as well as exhaust manifold, upstream, and / or downstream air-fuel ratio sensors. Catalyst 70 may include multiple catalyst bricks, in one example. In another example, multiple emission control devices, each with multiple bricks, may be used. The catalyst 70 may be a three-way type catalyst in one example.Controller 12 is shown in FIG. 1 as a microcomputer, including microprocessor unit 102, input / output interfaces 104, an electronic volume for executable programs and calibration, shown as read only memory chip 106 in this particular example, random access memory 108, keep alive memory (KAM) (battery powered memory for diagnostic information in automobiles) 110, and a data bus. Controller 12 may receive various signals and information from sensors coupled to engine 10, in addition to those signals discussed above, including measurement of inducted mass air flow (MAF) from mass air flow sensor 120, engine coolant temperature (ECT) from temperature sensor 112 coupled to cooling sleeve 114, a profile ignition pickup signal (PIP) from Hall effect sensor 118 (or other type) coupled to crankshaft 40, throttle position (TP) from a throttle position sensor, and intake manifold absolute pressure signal MAP from sensor 122. Volume random access memory 106 may be programmed with computer readable data representing instructions executable by processor 102 for carrying out the methods described below, as well as variations thereof. The engine cooling sleeve 114 may be coupled to a vehicle cabin heating system.The engine 10 may further include a compression device, such as a turbocharger or supercharger, including at least one compressor 162 disposed along the intake manifold 44. In a turbocharger, compressor 162 may be at least partially driven by a turbine 164 (e.g., via a shaft) arranged along exhaust passage 48. In a supercharger, compressor 162 may be at least partially driven by the engine and / or an electric motor and may not include a turbine. Therefore, the amount of compression (e.g., boost) provided to one or more cylinders of the engine via a turbocharger or supercharger may be varied by controller 12. Further, a sensor 123 may be disposed in the intake manifold 44 for providing a BOOST signal to the controller 12.FIG. 2 shows an example embodiment of an engine 200, which may be engine 10, including a variable cam control system (VCT) 202, a cam profile switching system (CPS) 204, a turbocharger 206, a catalyst 208, and a cylinder head 210 having a plurality of cylinders 212. The machine 200 may be an example of the machine 10 as described above. Engine 200 is shown having an intake manifold 214 configured to provide intake air and / or fuel to cylinders 212 and a segmented integrated exhaust manifold 216 configured to derive the combustion products from cylinders 212. Segmented exhaust manifold 216 may include a plurality of outlets coupled to different exhaust components, respectively. For example, an outlet may be coupled to catalyst 208, and an outlet may be coupled to turbocharger 206. Additional details regarding the exhaust manifold 216 are presented below. While the intake manifold 214 is separate from the cylinder head 210 while the exhaust manifold 216 is integrated with the cylinder head 210 in the embodiment depicted in FIG. 2, in other embodiments, the intake manifold 214 may be integrated and / or the exhaust manifold 216 may be separate from the cylinder head 210.The cylinder head 210 includes four cylinders denoted by C 1 to C 4. Cylinders 212 may each include a spark plug and a fuel injector for supplying fuel directly to the combustion chamber, as shown above in FIG. 1. However, in alternative embodiments, each cylinder may not include a spark plug and / or a direct fuel injector. The cylinders may each be supplied by one or more valves. In the present example, cylinders 212 each include two intake valves and two exhaust valves. Each intake valve and each exhaust valve is configured to open and close an intake port and an exhaust port, respectively. The intake valves are denoted by I1 to I8, and the exhaust valves are denoted by E1 to E8. The cylinder C1 has intake valves I1 and I2 and exhaust valves E1 and E2, the cylinder C2 has intake valves I3 and I4 and exhaust valves E3 and E4, the cylinder C3 has intake valves I5 and I6 and exhaust valves E5 and E6, and the cylinder C4 has intake valves I7 and I8 and exhaust valves E7 and E8. Each outlet port of each cylinder may have an equal diameter. However, in certain embodiments, certain of the outlet openings may have a different diameter. The outlet openings controlled by the outlet valves E 4 and E 5 may have, for example, a smaller diameter than the remaining outlet openings.Each intake valve may be actuated between an open position that admits intake air into a respective cylinder and a closed position that substantially blocks intake air from the respective cylinder. Further, FIG. 2 shows how intake valves I 1 through I 8 may be actuated by a common intake camshaft 218. The intake camshaft 218 includes a plurality of intake cams configured to control the opening and closing of the intake valves. Each intake valve may be controlled by first intake cams 220 and second intake cams 222. Further, in certain embodiments, one or more additional intake cams may be included to control the intake valves. In the present example, the first intake cams 220 have a first cam lobe profile for opening the intake valves for a first intake duration. Further, in the present example, the second intake cams 222 have a second cam lobe profile for opening the intake valve for a second intake duration. The second intake duration may be a shorter intake duration (shorter than the first intake duration), the second intake duration may be a longer intake duration (longer than the first intake duration), or the first and second intake durations may be the same. Additionally, the intake camshaft 218 may include one or more zero cam lobes. Zero cam lobes may be configured to maintain respective intake valves in the closed position.Each exhaust valve may be actuated between an open position that exhaust from a respective one of cylinders 212 and a closed position that substantially retains gases within the respective cylinder. Further, FIG. 2 shows how exhaust valves E 1 through E 8 may be actuated by a common exhaust camshaft 224. The exhaust camshaft 224 includes a plurality of exhaust cams configured to control the opening and closing of the exhaust valves. Each exhaust valve may be controlled by first exhaust cams 226 and second exhaust cams 228. Further, in certain embodiments, one or more additional exhaust cams may be included to control the exhaust valves. In the present example, the first exhaust cams 226 have a first cam lobe profile for opening the exhaust valves for a first exhaust duration. Further, in the present example, the second exhaust cams 228 have a second cam lobe profile for opening the exhaust valve for a second exhaust duration. The second exhaust duration may be shorter, longer, or equal to the first exhaust duration. Additionally, the exhaust camshaft 224 may include one or more zero cam lobes. Zero cam lobes may be configured to maintain respective exhaust valves in the closed position.Additional elements not shown may further include pushrods, rocker arms, followers, etc. Such devices and features may control actuation of the intake valves and the exhaust valves by converting rotational motion of the cams to translational motion of the valves. In other examples, the valves may be actuated via additional cam lobe profiles on the camshafts, where the cam lobe profiles between the different valves may provide different cam lift heights, cam duration, and / or cam control system. However, alternative camshaft arrangements (overhead and / or pushrod camshafts) could be used as desired. For example, in certain examples, cylinders 212 may each have only one exhaust valve and / or intake valve, or more than two intake and / or exhaust valves. In still further examples, the exhaust valves and intake valves may be actuated by a common camshaft. However, in an alternative embodiment, at least one of the intake valves and / or exhaust valves may be actuated by its own independent camshaft or other device.A subset of the exhaust valves of cylinders 212 may be deactivated, as desired, via one or more mechanisms. Exhaust valves E 4 and E 5 coupled to exhaust manifold 234 (explained in more detail below) may be deactivated via, for example, shift followers, shift rocker arms, or rolling finger cams. During operating modes where VDE is activated, intake valves may be deactivated using similar mechanisms.Engine 200 may include variable valve actuation systems, for example, CPS system 204 and variable cam control system VCT 202. A variable valve actuation system may be configured to operate in multi-modes. The first mode of operation may occur subsequent to an engine cold start, for example, when the engine temperature is below a threshold or for a given duration subsequent to an engine start. During the first mode, the variable valve actuation system may be configured to open only a subset of exhaust ports of a subset of cylinders, with all other exhaust ports closed. For example, only exhaust valves E 4 and E 5 of cylinders C 2 and C 3 may be opened. A second mode of operation may occur during the standard warmed-up engine operation. During the second mode, the variable valve actuation system may be configured to open all exhaust ports of all cylinders. Further, during the second mode of operation, the variable valve actuation system may be configured to open the subset of exhaust ports of the subset of cylinders for a shorter duration than the remaining exhaust ports. A third mode of operation may occur during warm-up engine operation with a low engine speed and high load. During the third mode, the variable valve operating system may be configured to maintain the subset of exhaust ports of the subset of cylinders closed while the remaining exhaust ports are opened, for example, opposite the first mode. In addition, the variable valve actuation system may be configured to selectively open and close the intake ports in accordance with opening and closing of the exhaust ports during the different operation modes.The CPS system 204 may be configured to longitudinally translate specific portions of the intake camshaft 218, thereby varying the operation of the intake valves I 1 to I 8 between first intake cams 220 and second intake cams 222 and / or other intake cams. Further, the CPS system 204 may be configured to longitudinally translate specific portions of the intake camshaft 224, thereby varying the operation of the intake valves E 1 to E 8 between first intake cams 226 and second intake cams 228 and / or other intake cams. In this way, the CPS system 204 may switch between multiple profiles. During the first mode of operation discussed above, the CPS system 204 may be switched to a first profile, for example. Further, the CPS system 204 may be switched to a second profile during the second mode of operation and to a third profile during the third mode of operation. Herein, the CPS system 204 may switch between a first cam to open a valve during a first duration, a second cam to open the valve during a second duration, and / or additionally or zero cams. The CPS system 204 may be controlled by the controller ( 201) via signal lines (the controller 201 is a non-limiting example of the controller 12 of FIG. 1 ).The configuration of cams described above may be used to provide control of the amount and timing of air supplied to and derived from the cylinders 212. However, other configurations may be used to enable the CPS system 204 to switch valve timing between two or more cams. For example, a switchable tappet or rocker arm may be used to vary valve timing between two or more cams.The engine 200 may further include the VCT system 202. The VCT system 202 may be a dual independent variable valve control system for changing intake valve timing and exhaust valve timing independently of each other. The VCT system 202 includes an intake camshaft phaser 230 and an exhaust camshaft phaser 232 to change valve timing. The VCT system 202 may be configured to advance or retard valve timing by advancing or retarding cam timing (an example engine operating parameter), and may be controlled by the controller 201 via signal lines. The VCT system 202 may be configured to vary the timing of the valve opening and closing events by varying the relationship between the crankshaft position and the camshaft position. For example, the VCT system system 202 may be configured to rotate the intake camshaft 218 and / or the exhaust camshaft 224 independently of the crankshaft to advance or retard valve timing. In certain embodiments, the VCT system 202 may be a cam torque actuated device configured to vary cam timing rapidly. In certain embodiments, valve timing such as intake valve closing (IVC) and exhaust valve closing (EVC) may be varied by a continuously variable valve lift device (CVVL). The valve / cam control devices and systems described above may be hydraulically, electrically, or combinedly driven. Signal lines may send control signals to and receive cam timing and / or cam selection measurement from the CPS system 204 and the VCT system 202.Referring again to the integrated exhaust manifold 216, it may be configured with multiple outlets to selectively direct exhaust gases to various exhaust components. The integrated exhaust manifold 216 may be a simple segmented exhaust manifold having multiple outlets in certain embodiments. In other embodiments, the cylinder head 210 may include a plurality of separate exhaust manifolds, each having an outlet. Further, the separate exhaust manifolds may be included in a common cast in the cylinder head 210. In the embodiment of FIG. 2, the exhaust manifold 216 includes a first exhaust manifold 234, second exhaust manifold 236, and, in certain embodiments, a third exhaust manifold 238.The first exhaust manifold 234 couples a subset of exhaust ports of a subset of the cylinders directly to the catalyst 208 and not to the turbocharger 206. As shown in FIG. 2, the exhaust ports of the exhaust valves E 4 and E 5 of the cylinders C 2 and C 3 are respectively coupled to the first exhaust manifold 234. The first exhaust manifold 234 includes a first inlet 240 coupled only to the exhaust port controlled by the exhaust valve E 4 and a second inlet 242 coupled only to the exhaust port controlled by the exhaust valve E 5. Further, the first exhaust manifold 234 includes an outlet 244 coupled to the catalyst 208. Thus, when the exhaust valves E 4 and E 5 open, the exhaust gases are directed through the first exhaust manifold 234 to the catalyst 208 without passing through the turbocharger 206. While the embodiment depicted in FIG. 2 couples the outlet 244 directly to the catalyst 208, in certain embodiments, the outlet 244 may be coupled to a common outlet passage 246 upstream of the catalyst 208 but not downstream of the turbocharger 206.The second exhaust manifold 236 includes an outlet 248 coupled to the turbocharger 206. The second exhaust manifold 236 couples at least a subset of the cylinders to the turbocharger 206. As shown in FIG. 2, each remaining exhaust port that is not coupled to the first exhaust manifold 234 is coupled to an inlet of the second exhaust manifold 236 (e.g., the exhaust ports of the exhaust valves E 1, E 2, E 3, E 6, E 7, and E 8 are coupled to only the second exhaust manifold 236). The second exhaust manifold includes, for example, a first inlet 250 coupled only to the exhaust port of the exhaust valve E 1 and a second inlet 252 coupled only to the exhaust port of the exhaust valve E 2, both of the outer cylinder C 1. The exhaust port controlled by the exhaust valve E 3 of the inner cylinder C 2 is coupled only to the third inlet 254 of the second exhaust manifold 236. The inner cylinder C 3 and the outer cylinder C 4 have similar inlets coupling their respective exhaust ports to the second exhaust manifold 236. Each exhaust port of the outer cylinders is therefore coupled to the second exhaust manifold 236, while only one exhaust port of the inner cylinders is coupled to the second exhaust manifold 236.However, in certain embodiments, the turbocharger 206 may be a twin scroll turbocharger. Therefore, a third exhaust manifold 238 may be present to couple a subset of cylinders to a collection housing of the twin scroll turbocharger. The second exhaust manifold 236 may be coupled to a first collection housing of the twin scroll turbocharger, and therefore only a portion of the exhaust ports not coupled to the first exhaust manifold may be coupled to the second exhaust manifold (e.g., the exhaust ports of E 1, E 2, E 7, and E 8). In such embodiments, the third exhaust manifold 238 may couple another subset of the remaining exhaust ports (e.g., the exhaust ports of E 3 and E 6) to a second collection housing of the twin scroll turbocharger.To further regulate boost pressure, turbocharger 206 includes turbine bypass valve 256. During certain conditions, the turbine bypass valve 256 may be opened to bypass a portion of the exhaust gases from the second and / or third exhaust manifolds around the turbocharger. Turbine bypass valve 256 may be opened to decrease exhaust backpressure, decrease boost pressure, etc., in response to signals from controller 201.An exhaust gas recirculation (EGR) system may direct a portion of the exhaust gases through the EGR passages 258, 260 to the inlet. The amount of EGR directed to the inlet may be regulated by EGR valves 262 and 264 receiving signals from controller 201. As shown in FIG. 2, the EGR system is configured to direct exhaust gases from only upstream of the turbocharger to the inlet in a high pressure EGR configuration. However, other configurations are possible. For example, the EGR system may be configured to direct exhaust gases from downstream of the turbocharger to the inlet at what is referred to as a low pressure EGR. By including multiple EGR passages, one that directs exhaust gases from the first exhaust manifold 234, and one that directs exhaust gases from the second exhaust chamber 236, the EGR system may selectively direct exhaust gases based on operating conditions. For example, under conditions where hot EGR is desired, EGR may be selectively directed from the EGR passage 258 to the inlet. However, if cooler EGR is desired, EGR may be selectively directed to the inlet from the EGR passage 260.As described above, FIG. 2 shows a non-limiting example of an internal combustion engine and associated intake and exhaust systems. It should be appreciated that in certain embodiments, the engine may have more or fewer combustion cylinders, control valves, throttle valves, and compression devices, among others. Example engines have cylinders arranged in a "V" configuration. Further, a first camshaft may control the intake valves for a first group or bank of cylinders, and a second camshaft may control the intake valves for a second group of cylinders. In this way, a single CPS system and / or VCT system may be used to control valve operation of a group of cylinders, or separate CPS and / or VCT systems may be used.FIG. 3 is a flow chart illustrating a method 300 for controlling exhaust flow in an engine. The method 300 may be executed according to instructions stored in the memory of a controller, such as controller 12 or 201. Method 300 may be performed in response to engine operating parameters determined by various engine sensors, such as ECT sensor 112, and may control different engine actuators, such as CPS system 204 and VCT system 202.The method 300 includes determining the machine operating parameters at 302. The engine operating parameters may include engine speed, load, temperature, number of engine cycles since engine start, camshaft timing, camshaft profile, etc. At 304, it is determined whether the engine is in cold start operation. The cold start operation may have an engine temperature below a threshold, such as 200° C. In other embodiments, the cold start operation may be determined based on a time since an engine start, such as within 30 seconds of the engine start. If it is determined that the engine is not in cold start operation, method 300 proceeds to 310, which is discussed in more detail below. If the engine is in cold start operation, method 300 proceeds to 306 to set a camshaft profile switching system, such as CPS system 204, to a first profile. The first profile is configured to open only a subset of exhaust ports of the machine. Specifically, the first profile only opens the exhaust ports coupled to a catalyst via a first exhaust manifold, such as first exhaust manifold 234, and not coupled to a turbocharger. As used herein, the term "opening an exhaust port" refers to the valve actuation system that opens an exhaust valve during a predetermined duration of the engine cycle, such as the exhaust stroke, to allow the exhaust port to be opened and expel exhaust gases. During the remaining parts of the engine cycle in which the exhaust port would normally be closed, the exhaust ports which are allowed to open during the exhaust stroke are kept closed. Further, the first profile comprises only a subset of the intake ports of the subset of cylinders that are allowed to open. For example, only one intake valve of cylinder C 2 and one intake valve of cylinder C 3 may be opened during the intake stroke while the remaining intake valves are maintained closed.At 308, the subset of cylinders coupled to the first exhaust manifold (e.g., cylinders C 2 and C 3 of FIG. 2 ) is ignited with the remaining cylinders remaining deactivated. As explained above, the engine may be configured to operate in a VDE mode where only a subset of the cylinders are fired. The fired cylinders receive fuel, intake air, and spark ignition to initiate combustion. The deactivated cylinders receive neither fuel nor spark ignition. Further, the first CPS profile includes only opening the intake valves of the subset of cylinders coupled to the catalyst. At this time, the non-fired cylinders (e.g., cylinders C 1 and C 4 of FIG. 2 ) do not receive intake air. Firing only the subset of cylinders coupled to the first exhaust manifold may include adjusting fuel distribution among the cylinders. For example, in standard operation, where all cylinders are fired, fuel may be distributed evenly among all cylinders. However, during VDE operation, where only a subset of the cylinders are receiving fuel, the amount of fuel delivered to the fired cylinders may be increased so that the same amount of total fuel is delivered to the engine during VDE operation as compared to non-VDE operation.At 310, it is determined whether the engine temperature has reached a threshold. The threshold may be the temperature of the warmed-up engine with the exhaust gases hot enough to maintain the catalyst at or above its light-off temperature, such as 200° C. If the engine has not reached the threshold, method 300 returns to continue operating with the first cam profile and ignite only a subset of the cylinders. If the engine has reached the threshold temperature, that is, if the engine is no longer in cold start operation, method 300 proceeds to 312 to determine if the engine is running under high load, low speed conditions. During high load, low speed conditions, the engine operates at peak torque and thus uses a large amount of boost to achieve the peak torque. However, at low engine speed, less exhaust pressure is generated and therefore all available exhaust gases are used to drive the turbine to generate the high amount of boost. High load may be a suitable load, such as a load above 50%, and low speed may be a suitable speed, such as below 1000 revolutions per minute. However, other load and speed ranges are possible. Further, high load and low speed conditions may be determined based on desired boost pressure and determined exhaust pressure, for example.If the engine is not running under high load, low speed conditions, method 300 proceeds to 314 to set the cam profile to a second profile. The second profile may be used during standard engine warm-up conditions, where the speed and load conditions are matched (e.g., low speed, low load), or otherwise the engine generates sufficient exhaust pressure to drive the turbine. The second cam profile may be configured to allow each exhaust port of each cylinder to open at its prescribed time. Each exhaust valve may be opened during each respective exhaust stroke, for example. The second cam profile may be further configured to delay opening of the exhaust ports coupled to the catalyst via the first exhaust manifold. For example, exhaust valves E 4 and E 5 of FIG. 2 may be opened 0-60° CA later than the remaining exhaust valves. Additionally, the second cam profile may be configured to allow each intake port of each cylinder to open during a respective intake stroke.At 318, method 300 includes firing all cylinders. Firing all cylinders includes injecting fuel to each cylinder and providing spark ignition to each cylinder. If the engine was previously running in VDE mode, fuel may be redistributed so that each cylinder receives the same amount of fuel. Further, at 320, the method 300 may include compensating for any torque disturbances occurring during the transition from the VDE mode. Prior to firing each cylinder, throttle plate position may be adjusted to increase air flow to the cylinders such that desired intake air is present in the intake manifold when intake valves of previously deactivated cylinders are allowed to open. To ensure that an over-rotation event does not occur when cylinder air flow is increased, spark timing in the fired cylinders may be retarded. Once the transition has occurred and all cylinders are firing, spark timing may be reset to MBT.During operation with the second cam profile, a portion of the exhaust gases are directed to the turbocharger via the second exhaust manifold (e.g., second exhaust manifold 236 of FIG. 2 ), and boost pressure is controlled by controlling the position of the turbine bypass valve. Because the exhaust ports coupled to the first exhaust manifold also open, a portion of the exhaust gases are directed to the catalyst and not the turbocharger via the first exhaust manifold. However, this portion may be smaller than the portion directed to the turbocharger due to the later opening timing of the exhaust valves E 4 and E 5 and / or due to the fact that these exhaust ports have a smaller diameter than the other exhaust ports. After setting the second cam profile and firing all cylinders, method 300 returns.Returning to 321, if it is determined that the engine is running at high load, low speed conditions, the cam profile is switched to a third profile at 316. The third profile is configured to maintain the exhaust ports coupled to the first exhaust manifold closed while allowing the remaining exhaust ports to open. Additionally, in certain embodiments, only one exhaust port per cylinder may be opened of the remaining exhaust ports. In the third cam profile, for example, only the exhaust ports E 2, E 3, E 6, and E 7 may be opened to maintain the combustion balance between the cylinders. The third profile is configured to direct all exhaust gases to the turbocharger before reaching the catalyst (e.g., no exhaust gases are directed through the first exhaust manifold). Further, under these conditions, the turbine bypass valve may be closed to produce a maximum of charge. Similar to the second cam profile, operation with the third cam profile at 318 includes firing each cylinder and compensating for torque disturbances during transition out of VDE mode at 320. Upon activating the third cam profile and firing all cylinders, method 300 returns.Therefore, method 300 provides for switching between multiple camshaft profiles depending on operating conditions. The camshaft profiles enable selective directing of exhaust gases to a catalyst, either by a turbocharger or bypassing the turbocharger. As shown below in Table 1, listing each cam profile and all exhaust valve states during respective exhaust strokes for each exhaust valve of the engine depicted in FIG. 2, the CPS system may switch between three cam profiles to optimize exhaust flow during the various modes of operation described above with reference to FIG. 3. Table 1 Table 11ClosedClosedClosedOpen open: OpenOpen open: OpenClosedClosedSlosure2Open open: OpenOpen open: OpenOpen open: OpenDelayDelayOpen open: OpenOpen open: OpenOpen open: Open3Optionally, the method is further further optionallyOpen open: OpenOpen open: OpenClosedClosedOpen open: OpenOpen open: OpenOptionally, the method is further further optionallyFIGS. 4-6 depict exhaust valve timing diagrams for two representative cylinders during each of the three operating modes (including the three CPS profiles depicted in Table 1). Exhaust valve timings for the valves of outer cylinder C 1 and inner cylinder C 2 are depicted. For each graph, timing is mapped into crankshaft angle degrees on the X axis. The exhaust valve opening state is mapped on the Y axis, respectively. An example firing order 1-3-4-2 is depicted in FIGS. 4-6, with combustion events marked with a star. Each stroke of the machine cycle is marked along the X axis. For each cylinder, an exhaust valve timing diagram (E 1 and E 3) is depicted by a solid line, while an exhaust valve timing diagram (E 2 and E 4) is depicted by a dashed-dotted line.FIG. 4 illustrates exhaust valve timing for the exhaust valves of cylinder 1 and cylinder 2 during the first cold start operation, with the first cam profile activated. During cold start conditions, a first cam profile is activated and VDE operation is enabled so that only exhaust ports coupled to a first exhaust manifold are opened. The first exhaust manifold is coupled to the catalyst and not to the turbocharger. Thus, under cold start conditions with the first cam profile, all exhaust gases are directed directly to the catalyst and not to the turbocharger. This allows for rapid catalyst heating by directing the exhaust gases to the catalyst on the shortest available exhaust path. As shown in FIG. 4, the engine is operating in VDE operation with the first cylinder deactivated and the exhaust valves of cylinder 1 remain closed during the duration of the engine cycle. For the cylinder 2, during each exhaust stroke, an exhaust valve (E4) is opened, which is shown as a dot-dash line. The other exhaust valve (E3) remains closed.FIG. 5 illustrates exhaust valve timing for the exhaust valves of cylinder 1 and cylinder 2 during the second default operating mode. Once the engine has warmed up, the second cam profile is activated to allow all exhaust ports to open. This allows a portion of the exhaust gases to be directed through the turbocharger and a smaller portion to be directed to the catalyst and not to the turbocharger. As such, most of the exhaust gases are directed to the turbocharger to allow the turbocharger to provide a desired amount of charge. As shown in FIG. 5, during the exhaust stroke, both exhaust valves of the cylinder 1 open (E 1 and E 2, solid line and dash-dotted line, respectively). In addition, during the exhaust stroke, both exhaust valves of the cylinder 2 open (E3 and E4, solid line and dash-dotted line, respectively). However, the exhaust valve E 4 has a retarded opening timing compared to the exhaust valve E 3.FIG. 6 illustrates exhaust valve timing for the exhaust valves of cylinder 1 and cylinder 2 during the third mode, the peak torque mode. A third cam profile allows all exhaust gases to be directed to the turbocharger. The third profile may be activated during conditions where maximum charging is indicated, such as low speed, high load conditions. The third profile may prevent the exhaust ports directly coupled to the catalyst from opening while the remaining exhaust ports are opened. As shown in FIG. 6, during the exhaust stroke, both exhaust valves of the cylinder 1 open (E 1 and E 2, solid line and dash-dotted line, respectively). However, for cylinder 2, only one exhaust valve opens (E 3, solid line) while exhaust valve E 4 remains closed.It is understood that the configurations and methods disclosed herein are exemplary in nature and that these specific embodiments should not be considered limiting as numerous variations are possible. The above technology can be applied to, for example, V-6, I-4, I-6, V-12, 4-cylinder box engines, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations, as well as other features, functions, and / or characteristics disclosed herein.The following claims particularly point out certain combinations and sub-combinations which are considered novel and non-obvious. These claims may refer to "a" element or "a first" element or equivalent. Such claims must be understood to include incorporation of one or more such elements that neither require nor exclude two or more such elements.

Claims

An engine method comprising: during a first condition, igniting a subset of second cylinders each including a first exhaust port coupled to a turbocharger via a second exhaust manifold and a second exhaust port coupled to a catalyst via a first exhaust manifold and not coupled to the turbocharger, and directing all exhaust gases from the subset of second cylinders through the first exhaust manifold and during a second condition, igniting all cylinders, namely the second cylinders and first cylinders including two exhaust ports coupled to the turbocharger via the second exhaust manifold, and directing a first portion of the exhaust gases through the second exhaust manifold and directing a second portion of the exhaust gases through the first exhaust manifold.The machine method of claim 1, wherein the first condition comprises an engine temperature below a threshold.The engine method of claim 1, wherein the second condition includes an engine temperature above a threshold and medium to high engine load.The engine method of claim 1, further comprising during a third condition, igniting all cylinders and directing all exhaust gases from each cylinder through the second exhaust manifold.The engine method of claim 4, wherein the third condition includes an engine temperature above a threshold, low speed, and medium to high engine load.The engine method of claim 1, wherein the engine is an in-line engine and wherein the subset of cylinders includes at least one inner cylinder.The engine method of claim 1, wherein directing all exhaust gases from the subset of cylinders through the first exhaust manifold further comprises activating a camshaft profile configured to open only a subset of exhaust ports of the subset of cylinders while all other exhaust ports are closed.The engine method of claim 1, wherein directing the first portion of the exhaust gases through the second exhaust manifold and directing the second portion of the exhaust gases through the first exhaust manifold further comprises activating a camshaft profile configured to open each exhaust port of each cylinder.The engine method of claim 8, wherein activating the camshaft profile configured to open each exhaust port of each cylinder further comprises activating a camshaft profile configured to open a subset of exhaust ports of the subset of cylinders later than all other exhaust ports.The engine method of claim 1, wherein the turbocharger is a twin scroll turbocharger, wherein directing the first portion of the exhaust gases through the second exhaust manifold coupled to the turbocharger further comprises directing the first portion of the exhaust gases to a first collection housing of the turbocharger, and further comprises directing a third portion of the exhaust gases through a third exhaust manifold coupled to a second collection housing of the turbocharger.An engine system comprising: a first cylinder including two exhaust ports coupled to a turbocharger via an integrated exhaust manifold; a second cylinder including a first exhaust port coupled to the turbocharger via the integrated exhaust manifold and a second exhaust port coupled to a catalyst and not coupled to the turbocharger; and a cam profile switching system configured to: allow only the second exhaust ports to open during a first condition and allow all exhaust ports to open during a second condition.The engine system of claim 11, wherein the first condition includes cold engine operation.The machine system of claim 11, wherein the second condition comprises operating with the machine warmed up.The engine system of claim 11, further comprising two inlet ports on each cylinder, and wherein the camshaft profile switching system is further configured to allow each inlet port to open during the first and second conditions.The engine system of claim 11, further comprising two intake ports on each cylinder, and wherein the camshaft profile switching system is further configured to: allow each intake port of the first cylinder to open during the first and second conditions, allow only one intake port of the second cylinder to open during the first condition, and allow each intake port of the second cylinder to open during the second condition.The engine system of claim 11, wherein the first outlet port of the second cylinder has a larger diameter than the second outlet port of the second cylinder.The engine system of claim 11, wherein the cam profile switching system is further configured to open the second exhaust port later than the first exhaust port during the second condition.A method for an engine having a plurality of cylinders, each cylinder having two exhaust valves, comprising: during a low speed, high load condition, deactivating a subset of exhaust valves and activating at least a portion of the remaining exhaust valves, wherein the subset of exhaust valves controls exhaust ports coupled to a catalyst via a first exhaust manifold, and the remaining exhaust valves controls exhaust ports coupled to a turbocharger via a second exhaust manifold, and during the medium to high load and speed condition, activating all exhaust valves of the engine.The method of claim 18, wherein activating at least a portion of the remaining exhaust valves further comprises activating all of the remaining exhaust valves.The method of claim 18, wherein disabling a subset of exhaust valves and enabling at least a portion of the remaining exhaust valves further comprises enabling an exhaust valve per cylinder while disabling an exhaust valve per cylinder.

Images