System and method for a split exhaust engine system

Abstract

The present application relates to systems and methods for a split exhaust engine system. A method and system for operating a split exhaust engine system are provided, which provides blow-through air and exhaust gas recirculation (EGR) to an intake passage via a scavenging manifold with an air passage. In one example, the scavenging manifold with an air passage includes a first scavenging manifold coupled to a plurality of exhaust runners via an air passage and a second scavenging manifold coupled to a plurality of exhaust runners via an air passage. The position of the air passage on the exhaust runner is combined with the adjustment of a bypass valve coupled between the first scavenging manifold and the exhaust passage and an EGR valve coupled between the second scavenging manifold and the intake passage, so that under selected operating conditions, the exhaust gas can preferably flow to the exhaust passage and the blow-through air can preferably flow to the intake passage.

Description

Technical Field

[0001] The present description generally relates to methods and systems for exhaust gas recirculation in an engine having a split exhaust system including a dual, ported scavenge manifold. Background Art

[0002] The engine may use a boost device (such as a turbocharger) to increase the engine power density. However, due to the increase in combustion temperature, engine knock may occur. Due to the high charge temperature, knock is particularly problematic under boost conditions. The inventors have recognized that a split exhaust system can reduce engine knock and improve engine efficiency, in which a first exhaust manifold delivers exhaust gas to a turbine of a turbocharger in the exhaust of the engine and a second exhaust manifold delivers exhaust gas recirculation (EGR) to an intake device of the engine upstream of the compressor of the turbocharger. In this engine system, each cylinder may include two intake valves and two exhaust valves, wherein a first set of cylinder exhaust valves (e.g., blow-off exhaust valves) are uniquely coupled to the first exhaust manifold, and a second set of cylinder exhaust valves (e.g., scavenging exhaust valves) are uniquely coupled to the second exhaust manifold. The first set of cylinder exhaust valves may be operated at a different timing from the second set of cylinder exhaust valves, thereby isolating the blow-off portion and the scavenging portion of the exhaust gas. The timing of the exhaust valves of the second group of cylinders may also be coordinated with the timing of the intake valves of the cylinders to produce a positive valve overlap period, wherein fresh intake air (or a mixture of fresh intake air and EGR) referred to as blowthrough may flow through the cylinders via an EGR passage coupled to the second exhaust manifold and back to the intake device upstream of the compressor. The blowthrough air may remove residual exhaust gas (referred to as scavenging) within the cylinders. The inventors have recognized that by flowing a first portion of the exhaust gas (e.g., higher pressure exhaust gas) through the turbine and the higher pressure exhaust passage and flowing a second portion of the exhaust gas (e.g., lower pressure exhaust gas) and the blowthrough air to the compressor inlet, the combustion temperature may be reduced while improving the operating efficiency of the turbine and the engine torque.

[0003] However, the inventors herein have recognized potential problems with such systems. As an example, the flow rate or amount of EGR may be regulated via an EGR valve disposed in the EGR passage. When the turbine speed is low (e.g., low engine speed / high load) or when the compressor inlet temperature is high (e.g., high engine speed / high load), the EGR flow may be limited by closing or partially closing the EGR valve. Under such restricted EGR flow conditions, the second exhaust manifold may become pressurized. When the second set of cylinder exhaust valves are opened during a subsequent engine cycle, pressurized gas comprising a mixture of EGR and fresh intake air may flow back into the cylinder and out of the first set of cylinder exhaust valves. However, excess oxygen in the blow-through air may degrade the catalyst located downstream of the turbine. Summary of the invention

[0004] In one example, the above problem can be solved by a method for an engine, the method comprising: flowing a first portion of exhaust gas from a first group of cylinder exhaust valves to an exhaust passage upstream of a turbocharger turbine; and from a second group of cylinder exhaust valves: first, flowing a second portion of exhaust gas to the exhaust passage downstream of the turbocharger turbine and upstream of a catalyst; and then, flowing blow-through air to an intake passage upstream of a turbocharger compressor. In this way, both EGR flow to the turbocharger compressor and excess oxygen flow to the catalyst can be reduced.

[0005] As an example, a second portion of the exhaust gas may flow from the exhaust valves of the second group of cylinders to the exhaust passage via the first scavenging manifold. The first scavenging manifold may be coupled to the exhaust passage downstream of the turbocharger turbine and upstream of the catalyst via a scavenging manifold bypass in which a bypass valve is disposed. In addition, the blow-in air may flow from the exhaust valves of the second group of cylinders to the intake passage via the second scavenging manifold, which is fluidly coupled to the first scavenging manifold via a plurality of ports and exhaust runners. The second scavenging manifold may be coupled to the intake passage via an EGR passage in which an EGR valve is disposed. By opening the bypass valve while maintaining the EGR valve at least partially open, the blow-in air preferably flows to the intake passage upstream of the turbocharger compressor via the second scavenging manifold, while the exhaust gas preferably flows to the exhaust passage via the first scavenging manifold. In this way, pressurization of the scavenging manifold is avoided while still reducing the EGR flow to the turbocharger compressor. By continuing to flow the cold blow-in air to the compressor inlet, the compressor inlet temperature may be reduced. In addition, by preventing the blowing air from flowing to the catalyst, catalyst degradation can be reduced.

[0006] It should be understood that the above summary is provided to introduce a selection of concepts further described in the detailed description in a simplified form. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is solely defined by the appended claims. Furthermore, the claimed subject matter is not limited to implementations that address any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1A A schematic diagram showing a turbocharged engine system with a split exhaust system.

[0008] Figure 1B Show Figure 1A An embodiment of a cylinder of an engine system.

[0009] Figure 2 An embodiment of a scavenging manifold with air ports for a split exhaust system is shown.

[0010] Figure 3 Example cylinder intake valve timing and exhaust valve timing are shown for one engine cylinder of a split exhaust engine system.

[0011] Figure 4 An example graph depicting relative gas composition in an exhaust runner coupled to a scavenging manifold with ports at different crank angles of an engine cycle is shown.

[0012] Figure 5 An example of the change in gas composition at the scavenging manifold port relative to cylinder valve timing is shown.

[0013] Figure 6 An example method for adjusting valve position to supply residual exhaust gas to an exhaust passage via a first scavenging manifold and blow-off air to an inlet of a compressor via a second scavenging manifold during restricted compressor flow conditions is provided.

[0014] Figure 7 An example graph showing changes in engine operating parameters when operating a split exhaust engine system during restricted compressor flow conditions.

[0015] Figure 2 Shown approximately to scale. DETAILED DESCRIPTION

[0016] The following description relates to systems and methods for operating a split exhaust engine with blow-through and exhaust gas recirculation (EGR) to an intake via a first exhaust manifold. Figure 1AAs shown, a split exhaust engine may include a first exhaust manifold (referred to herein as a blow-off exhaust manifold) uniquely coupled to the blow-off exhaust valve of each cylinder. The blow-off manifold is coupled to an exhaust passage of the engine, wherein the exhaust passage includes a turbocharger turbine and one or more emission control devices (which may include one or more catalysts). Figure 1A shown and in Figure 2 As described in , the split exhaust engine may also include a first scavenging manifold uniquely coupled to the scavenging exhaust valve of each cylinder via an exhaust runner and a second scavenging manifold connected from each exhaust runner through an air passage. The first scavenging manifold is coupled to the exhaust passage of the engine downstream of the turbocharger turbine via a scavenging manifold bypass passage including a scavenging manifold bypass valve (SMBV), and the second exhaust manifold is coupled to the intake passage upstream of the turbocharger compressor via a first EGR passage including a first EGR valve (referred to herein as a BTCC valve). In addition, in some embodiments, the split exhaust engine system may include various valve actuation mechanisms and may be installed in a hybrid vehicle, such as Figure 1B The scavenging exhaust valve and the exhaust exhaust valve of each cylinder can be opened and closed at different timings in the engine cycle to isolate the scavenging part and the exhaust part of the combustion exhaust gas and guide these parts to the first scavenging manifold and the second scavenging manifold and the exhaust manifold, respectively, as shown in FIG. Figure 3 In addition, due to the gas composition gradient in the exhaust flow channel, as shown in Figures 4 to 5 As shown, the scavenging portion of the combusted exhaust gas may be preferably supplied to the exhaust passage via the first scavenging manifold, while the unburned blow-by air may be preferably supplied to the compressor inlet via the second scavenging manifold via regulation of the BTCC valve and the SMBV under selected operating conditions (e.g., when a restricted compressor flow is desired), such as according to Figure 6 Example method of . Figure 7 An example timing diagram for adjusting the BTCC valve and SMBV in response to a restricted compressor flow condition is shown. For example, under certain engine operating conditions, such as when the compressor temperature reaches an upper threshold temperature, it may be desirable to reduce flow to the compressor inlet. By preferentially allowing hotter exhaust gas to flow from the scavenging exhaust valve to the exhaust via the scavenging manifold bypass passage, and allowing cooler blow-off air to flow to the compressor inlet via the EGR passage, the temperature and airflow at the compressor can be reduced while reducing the amount of oxygen-containing air flowing to the exhaust passage.

[0017] In the following description, a valve being operated or actuated indicates that it opens and / or closes according to a timing determined for a given set of conditions during a combustion cycle. Likewise, a valve being deactivated or not operating indicates that the valve remains closed unless otherwise stated.

[0018] Figure 1AA schematic diagram of a multi-cylinder internal combustion engine 10 that may be included in a propulsion system of an automobile is shown. Engine 10 includes a plurality of combustion chambers (i.e., cylinders) that may be capped at the top by a cylinder head (not shown). Figure 1A In the example shown, engine 10 includes cylinders 13, 14, 15 and 18 arranged in an inline 4 cylinder configuration. However, it should be understood that although Figure 1A Four cylinders are shown, but engine 10 may include any number of cylinders in any configuration, such as a V-6, I-6, V-12, opposed 4, etc. Additionally, as further described below, Figure 1A The cylinder shown may have a cylinder configuration such as Figure 1B Cylinder configuration shown. Each of cylinders 13, 14, 15 and 18 includes two intake valves, including a first intake valve 2 and a second intake valve 4, and two exhaust valves, including a first exhaust valve (referred to herein as a blow-off exhaust valve or blow-off valve) 8 and a second exhaust valve (referred to herein as a scavenging exhaust valve or scavenging valve) 6. The intake valve and the exhaust valve may be referred to herein as a cylinder intake valve and a cylinder exhaust valve, respectively.

[0019] As reference below Figure 1B As further explained, the timing of each of the intake valves (e.g., opening timing, closing timing, opening duration, etc.) may be controlled via various camshaft timing systems. In one embodiment, both the first intake valve 2 and the second intake valve 4 may be controlled with the same valve timing (e.g., such that they open and close at the same time in an engine cycle). In an alternative embodiment, the first intake valve 2 and the second intake valve 4 may be controlled with different valve timings. Additionally, the first exhaust valve 8 may be controlled with a different valve timing than the second exhaust valve 6 (e.g., such that the first exhaust valve and the second exhaust valve of the same cylinder open at different times from each other and close at different times from each other), as discussed further below.

[0020] Each cylinder receives intake air (or a mixture of intake air and recirculated exhaust gas, as explained further below) from intake manifold 44 via intake passage 28. Intake manifold 44 is coupled to the cylinders via intake passages (e.g., runners). Figure 1A 2 is shown as being coupled to each first intake valve 2 of each cylinder via a first intake passage 20. In addition, intake manifold 44 is coupled to each second intake valve 4 of each cylinder via a second intake passage 22. In this way, each cylinder intake passage can selectively communicate with the cylinder to which it is coupled via a corresponding one of the first intake valve 2 or the second intake valve 4. Each intake passage can supply air and / or fuel to the cylinder to which it is coupled for combustion.

[0021] One or more of the intake passages may include a charge motion control device, such as a charge motion control valve (CMCV). Figure 1A As shown, each first intake port 20 of each cylinder includes a CMCV 24. The CMCV 24 may also be referred to as a swirl control valve or a tumble control valve. The CMCV 24 may restrict the airflow into the cylinder via the first intake valve 2. Figure 1A In the example of FIG. 1 , each CMCV 24 may include a valve plate; however, other designs of valves are possible. Note that for purposes of this disclosure, when the CMCV 24 is fully actuated, the CMCV 24 is in a "closed" position and the valve plate may be fully tilted into the corresponding first intake passage 20, thereby causing maximum air charge flow obstruction. Alternatively, the CMCV 24 is in an "open" position when deactivated and the valve plate may be fully rotated to be substantially parallel to the air flow, thereby significantly minimizing or eliminating air charge flow obstruction. The CMCV may be primarily maintained in its "open" position and may be activated "closed" only when vortex conditions are desired.

[0022] like Figure 1A As shown, only one intake port in each cylinder includes CMCV 24. However, in an alternative embodiment, both intake ports of each cylinder may include CMCV 24. Controller 12 may actuate CMCV 24 (e.g., via a valve actuator that may be coupled to a rotating shaft directly coupled to each CMCV 24) in response to engine operating conditions (such as engine speed / load and / or when blow-through via second exhaust valve 6 is activated) to move the CMCV to an open position or a closed position, or a plurality of positions between the open position and the closed position. As referred to herein, blow-through air or blow-through combustion cooling (BTCC) may refer to intake air flowing from one or more intake valves of each cylinder to second exhaust valve 6 during a valve opening overlap period between the intake valve and second exhaust valve 6 (e.g., a period of time when the intake valve and second exhaust valve 6 are simultaneously open) to the second exhaust valve 6 without burning the blow-through air.

[0023] High pressure dual stage fuel systems (such as Figure 1B The fuel system shown in FIG. 1 may be used to generate fuel pressure at injector 66. In this way, fuel may be injected directly into the cylinder via injector 66. Distributorless ignition system 88 provides an ignition spark to cylinders 13, 14, 15, and 18 via spark plugs 92 in response to controller 12. Cylinders 13, 14, 15, and 18 are each coupled to two exhaust passages for respectively directing a blow-off portion and a scavenging portion of the combustion gases. Specifically, as shown in FIG. Figure 1AAs shown, cylinders 13, 14, 15 and 18 discharge a first portion of combustion gases (e.g., a blow-off portion) to a first exhaust manifold (referred to herein as a blow-off manifold) 84 via a first exhaust runner (e.g., an air passage) 86, and discharge a second portion of combustion gases (e.g., a scavenging portion) to a first scavenging manifold 79 via a second exhaust runner (e.g., an air passage) 82 and / or to a second scavenging manifold 80 via a second exhaust runner 82 and an air passage 83. The first scavenging manifold 79 and the second scavenging manifold 80 may be collectively referred to herein as a second exhaust manifold. The second exhaust runner 82 extends from cylinders 13, 14, 15 and 18 to the first scavenging manifold 79. In addition, the second exhaust runner 82 is coupled to the second scavenging manifold 80 via an air passage 83, wherein each of the air passages 83 is coupled to one of the second exhaust runners 82. Therefore, the scavenging portion of the combustion gases may flow to both the first scavenging manifold 79 and the second scavenging manifold 80. Reference will be made to the following. Figure 2 The configuration of the first scavenging manifold 79, the second scavenging manifold 80, and the air passage 83 is further described. In addition, the first exhaust manifold 84 includes a first manifold portion 81 and a second manifold portion 85. The first exhaust runners 86 of the cylinders 13 and 18 (referred to herein as outer cylinders) extend from the cylinders 13 and 18 to the second manifold portion 85 of the first exhaust manifold 84. In addition, the first exhaust runners 86 of the cylinders 14 and 15 (referred to herein as inner cylinders) extend from the cylinders 14 and 15 to the first manifold portion 81 of the first exhaust manifold 84.

[0024] Each exhaust runner can be selectively connected to the cylinder coupled to it via an exhaust valve. For example, the second exhaust runner 82 is connected to their corresponding cylinders via the second exhaust valve 6, and the first exhaust runner 86 is connected to their corresponding cylinders via the first exhaust valve 8. When at least one exhaust valve in each cylinder is in a closed position, the second exhaust runner 82 is isolated from the first exhaust runner 86. Exhaust gas cannot flow directly between the exhaust runners 82 and 86. The above-mentioned exhaust system may be referred to as a split exhaust manifold system in this article, wherein a first portion of the exhaust gas from each cylinder is output to the first exhaust manifold 84, and a second portion of the exhaust gas from each cylinder is output to the first scavenging manifold 79, wherein the first exhaust manifold is not directly connected to the scavenging manifold (for example, there is no passage to directly couple the first exhaust manifold to the first scavenging manifold or the second scavenging manifold, and therefore the first and second portions of the exhaust gas do not mix with each other in the first exhaust manifold and the scavenging manifold).

[0025] The engine 10 includes a turbocharger including a dual-stage exhaust turbine 164 and an intake compressor 162 coupled on a common shaft. The dual-stage turbine 164 includes a first turbine 163 and a second turbine 165. The first turbine 163 is directly coupled to the first manifold portion 81 of the first exhaust manifold 84 and receives exhaust gas from cylinders 14 and 15 only via the first exhaust valves 8 of cylinders 14 and 15. The second turbine 165 is directly coupled to the second manifold portion 85 of the first exhaust manifold 84 and receives exhaust gas from cylinders 13 and 18 only via the first exhaust valves 8 of cylinders 13 and 18. The rotation of the first turbine and the second turbine drives the rotation of the compressor 162 disposed in the intake passage 28. In this way, the intake air is boosted (e.g., pressurized) at the compressor 162 and travels downstream to the intake manifold 44. The exhaust gas leaves both the first turbine 163 and the second turbine 165 and enters the common exhaust passage 74. A wastegate may be coupled to both sides of the dual-stage turbine 164. Specifically, a wastegate valve 76 may be included in a bypass 78 between each of the first manifold portion 81 and the second manifold portion 85 coupled upstream of the inlet of the dual-stage turbine 164 and the exhaust passage 74 downstream of the outlet of the dual-stage turbine 164. In this manner, the position of the wastegate valve (referred to herein as a turbine wastegate) 76 controls the amount of boost provided by the turbocharger. In an alternative embodiment, the engine 10 may include a single-stage turbine in which all exhaust gas from the first exhaust manifold 84 is directed to the inlet of the same turbine.

[0026] Exhaust gas leaving dual-stage turbine 164 flows downstream in exhaust passage 74 to first emission control device 70 and second emission control device 72, which is arranged downstream in exhaust passage 74 from first emission control device 70. In one example, emission control devices 70 and 72 may include one or more catalyst bricks. In some examples, emission control devices 70 and 72 may be three-way catalysts (TWC). In other examples, emission control devices 70 and 72 may include one or more of a diesel oxidation catalyst (DOC) and a selective catalytic reduction catalyst (SCR). In yet another example, second emission control device 72 may include a particulate filter, such as a gasoline particulate filter (GPF) or a diesel particulate filter (DPF). In one example, first emission control device 70 may include a catalyst, and second emission control device 72 may include a GPF. After passing through emission control devices 70 and 72, the exhaust gas may be directed to a tail pipe.

[0027] As described further below, exhaust passage 74 also includes a plurality of exhaust gas sensors in electronic communication with controller 12 of control system 17. Figure 1AAs shown, exhaust passage 74 includes a first oxygen sensor 90 located between first emission control device 70 and second emission control device 72. First oxygen sensor 90 may be configured to measure the oxygen content of exhaust gas entering second emission control device 72. Exhaust passage 74 may include one or more additional oxygen sensors positioned along exhaust passage 74, such as a second oxygen sensor 91 located between dual-stage turbine 164 and first emission control device 70 and / or a third oxygen sensor 93 located downstream of second emission control device 72. In this way, second oxygen sensor 91 may be configured to measure the oxygen content of exhaust gas entering first emission control device 70, and third oxygen sensor 93 may be configured to measure the oxygen content of exhaust gas leaving second emission control device 72. In one embodiment, one or more oxygen sensors 90, 91, and 93 may be universal exhaust gas oxygen (UEGO) sensors. Alternatively, a two-state exhaust gas oxygen sensor may replace oxygen sensors 90, 91, and 93.

[0028] Exhaust passage 74 may include various other sensors, such as one or more temperature and / or pressure sensors. Figure 1A As shown, pressure sensor 96 is located in exhaust passage 74 between first emission control device 70 and second emission control device 72. As such, pressure sensor 96 may be configured to measure the pressure of exhaust gas entering second emission control device 72. Both pressure sensor 96 and oxygen sensor 90 are disposed in exhaust passage 74 at a point where flow passage 98 is coupled to exhaust passage 74. Flow passage 98 may be referred to herein as a scavenging manifold bypass passage (SMBP) 98. Scavenging manifold bypass passage 98 is directly coupled to and between first scavenging manifold 79 and exhaust passage 74. Valve 97 (referred to herein as a scavenging manifold bypass valve SMBV) is disposed in scavenging manifold bypass passage 98 and may be actuated by controller 12 to adjust the amount of exhaust gas flow from first scavenging manifold 79 to exhaust passage 74 between first emission control device 70 and second emission control device 72.

[0029] The second scavenging manifold 80 is directly coupled to the first exhaust gas recirculation (EGR) passage 50. The first EGR passage 50 is directly coupled between the second scavenging manifold 80 and the intake passage 28 upstream of the compressor (e.g., turbocharger compressor) 162, and thus may be referred to as a low-pressure EGR passage. In this way, exhaust gas (or blow-by air, as further explained below) is directed from the first scavenging manifold 79 to the second scavenging manifold 80 via the air passage 83, and then directed to the intake passage 28 upstream of the compressor 162 via the first EGR passage 50. Figure 1AAs shown, the first EGR passage 50 includes an EGR cooler 52 and a first EGR valve 54 (which may be referred to herein as a BTCC valve) configured to cool the exhaust gas flowing from the first scavenging manifold and the second scavenging manifold to the intake passage 28. The controller 12 is configured to actuate and adjust the position of the first EGR valve 54 so as to control the amount of air flow flowing through the first EGR passage 50. When the first EGR valve 54 is in a closed position, no exhaust or intake air may flow from the first scavenging manifold 79 and the second scavenging manifold 80 to the intake passage 28 upstream of the compressor 162. In addition, when the first EGR valve 54 is in an open position, exhaust and / or blow-through air may flow from the first scavenging manifold 79 and the second scavenging manifold 80 to the intake passage 28 upstream of the compressor 162. The controller 12 may additionally adjust the first EGR valve 54 to a plurality of positions between fully open and fully closed.

[0030] A first ejector 56 is located at the outlet of the first EGR passage 50 within the intake passage 28. The first ejector 56 may include a constriction or a venturi that provides a pressure increase at the inlet of the compressor 162. As a result, the EGR from the first EGR passage 50 may be mixed with the fresh air flowing through the intake passage 28 to the compressor 162. Therefore, the EGR from the first EGR passage 50 may act as a motive flow on the first ejector 56. In an alternative embodiment, there may be no ejector located at the outlet of the EGR passage 50. Instead, the outlet of the compressor 162 may be shaped as an ejector that reduces air pressure to assist the EGR flow (and therefore in this embodiment, air is a motive flow and EGR is a secondary flow). In yet another embodiment, the EGR from the EGR passage 50 may be introduced at the trailing edge of the blades of the compressor 162, thereby allowing the blow-in air to pass through the first EGR passage 50 to the intake passage 28.

[0031] The second EGR passage 58 may be coupled between the first EGR passage 50 and the intake passage 28. Figure 1A As shown, the second EGR passage 58 is coupled to the first EGR passage 50 between the EGR valve 54 and the EGR cooler 52. In an alternative embodiment, when the second EGR passage 58 is included in the engine system, the system may not include the EGR cooler 52. In addition, the second EGR passage 58 is directly coupled to the intake passage 28 downstream of the compressor 162. Due to this coupling, the second EGR passage 58 may be referred to herein as a medium pressure EGR passage. In addition, as Figure 1AAs shown, the second EGR passage 58 is coupled to the intake passage 28 upstream of the charge air cooler (CAC) 40. The CAC 40 is configured to cool the intake air (which may be a mixture of fresh intake air and exhaust gas from outside the engine system) as it passes through the CAC 40. In this way, the recirculated exhaust gas from the first EGR passage 50 and / or the second EGR passage 58 may be cooled by the CAC 40 before entering the intake manifold 44. In an alternative embodiment, the second EGR passage 58 may be coupled to the intake passage 28 downstream of the CAC 40. In this embodiment, the EGR cooler 52 disposed in the first EGR passage 50 may not be present. In addition, as shown in FIG. Figure 1A As shown, second ejector 57 may be located within intake passage 28 at the outlet of second EGR passage 58 .

[0032] A second (e.g., medium pressure) EGR valve 59 is disposed in the second EGR passage 58. The second EGR valve 59 is configured to adjust the amount of gas flow (e.g., blow-through air or exhaust) through the second EGR passage 58. The controller 12 may actuate the EGR valve 59 to an open position (allowing flow through the second EGR passage 58), a closed position (blocking flow through the second EGR passage 58), or multiple positions between fully open and fully closed based on (e.g., according to) engine operating conditions. For example, actuating the EGR valve 59 may include the controller 12 sending an electronic signal to an actuator of the EGR valve 59 to move a valve plate of the EGR valve 59 to an open position, a closed position, or some position between fully open and fully closed. Based on the system pressure in the engine system and the position of the alternative valve, air may flow toward the intake passage 28 in the second EGR passage 58 or toward the second scavenging manifold 80 in the second EGR passage 58.

[0033] Intake passage 28 also includes an electronic intake throttle valve 62 that communicates with intake manifold 44. Figure 1AAs shown, intake throttle 62 is located downstream of CAC 40. The position of throttle plate 64 of throttle 62 can be adjusted by control system 17 via a throttle actuator (not shown) that is communicatively coupled to controller 12. By adjusting intake throttle 62 while operating compressor 162, a certain amount of fresh air can be introduced from the atmosphere and / or a certain amount of recirculated exhaust gas can be introduced from one or more EGR passages and delivered to the engine cylinders at a boost pressure via intake manifold 44. In order to reduce compressor surge, at least a portion of the charge compressed by compressor 162 can be recirculated to the compressor inlet. A compressor recirculation passage 41 can be provided for recirculating compressed air from the compressor outlet upstream of CAC 40 to the compressor inlet. A compressor recirculation valve (CRV) 42 can be provided for regulating the amount of recirculation flow recirculated to the compressor inlet. In one example, CRV 42 can be actuated to open in response to an actual or expected compressor surge condition via a command from controller 12.

[0034] The third flow passage 30 (which may be referred to herein as a heat pipe) is coupled between the second scavenging manifold 80 and the intake passage 28. Specifically, a first end of the third flow passage 30 is directly coupled to the second scavenging manifold 80, and a second end of the third flow passage 30 is directly coupled to the intake passage 28 downstream of the intake throttle 62 and upstream of the intake manifold 44. A third valve 32 (e.g., a heat pipe valve) is disposed within the third flow passage 30 and is configured to adjust an amount of air flow through the third flow passage 30. In response to an actuation signal sent from the controller 12 to an actuator of the third valve 32, the third valve 32 may be actuated to a fully open position, a fully closed position, or a plurality of positions between fully open and fully closed.

[0035] The first scavenging manifold 79, the second scavenging manifold 80 and / or the second exhaust runner 82 may include one or more sensors (such as a pressure sensor, an oxygen sensor and / or a temperature sensor) disposed therein. Figure 1A As shown, the first scavenging manifold 79 includes a pressure sensor 34 and an oxygen sensor 36 disposed therein and configured to measure the pressure and oxygen content of the exhaust and blow-through (e.g., intake) air, respectively, leaving the second exhaust valve 6 and entering the first scavenging manifold 79. In addition to or alternatively to the oxygen sensor 36, each second exhaust runner 82 may include a separate oxygen sensor 38 disposed therein. In this way, the oxygen content of the exhaust and / or blow-through air leaving each cylinder via the second exhaust valve 6 may be determined based on the output of the oxygen sensor 38. In other examples, the second scavenging manifold 80 may additionally or alternatively include a pressure sensor and an oxygen sensor disposed therein and configured to measure the pressure and oxygen content of the exhaust and blow-through air, respectively, entering the second scavenging manifold 80 from the second exhaust runner 82 via the air passage 83.

[0036] In some embodiments, Figure 1A As shown, the intake passage 28 may include an electric compressor 60. The electric compressor 60 is disposed in a bypass passage 61, which is coupled to the intake passage 28 upstream and downstream of an electric compressor valve 63. Specifically, an inlet of the bypass passage 61 is coupled to the intake passage 28 upstream of the electric compressor valve 63, and an outlet of the bypass passage 61 is coupled to the intake passage 28 downstream of the electric compressor valve 63 and upstream of a position where the first EGR passage 50 is coupled to the intake passage 28. In addition, the outlet of the bypass passage 61 is coupled upstream of a turbocharger compressor 162 in the intake passage 28. The electric compressor 60 may be electrically driven by an electric motor using energy stored at an energy storage device. In one example, as Figure 1A As shown, the electric motor may be part of electric compressor 60. When additional boost (e.g., increased pressure of intake air above atmospheric pressure) is requested above the amount provided by compressor 162, controller 12 may activate electric compressor 60 so that it rotates and increases the pressure of intake air flowing through bypass passage 61. Additionally, controller 12 may actuate electric compressor valve 63 to a closed or partially closed position to direct the increased amount of intake air through bypass passage 61 and electric compressor 60.

[0037] Intake passage 28 may include one or more additional sensors (such as additional pressure sensors, temperature sensors, flow rate sensors, and / or oxygen sensors). For example, Figure 1A As shown, intake passage 28 includes a mass air flow (MAF) sensor 48 disposed upstream of compressor 162, electric compressor valve 63, and the location where first EGR passage 50 is coupled to intake passage 28. An intake air pressure sensor 31 and an intake air temperature sensor 33 are located in intake passage 28 upstream of compressor 162 and downstream of the location where first EGR passage 50 is coupled to intake passage 28. An intake oxygen sensor 35 and an intake air temperature sensor 43 may be positioned in intake passage 28 downstream of compressor 162 and upstream of CAC 40. An additional intake air pressure sensor 37 may be located in intake passage 28 downstream of CAC 40 and upstream of throttle 62. In some embodiments, as shown in FIG. Figure 1A As shown, an additional intake oxygen sensor 39 may be located in intake passage 28 between CAC 40 and throttle 62. Additionally, an intake manifold pressure (eg, MAP) sensor 122 and an intake manifold temperature sensor 123 are located within intake manifold 44 upstream of all engine cylinders.

[0038] In some examples, engine 10 may be coupled to an electric motor / battery system in a hybrid vehicle (eg, Figure 1B). The hybrid vehicle may have a parallel configuration, a series configuration, or a variation or combination thereof. In addition, in some embodiments, other engine configurations may be employed, such as a diesel engine.

[0039] Engine 10 may be controlled at least partially by control system 17 (including controller 12) and may be controlled via input devices ( Figure 1A The engine 10 is controlled by input from a vehicle operator (not shown). The control system 17 is shown as receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 99. As an example, as described above, the sensors 16 may include pressure sensors, temperature sensors, and oxygen sensors located within the intake passage 28, the intake manifold 44, the exhaust passage 74, and the first scavenging manifold 79. Other sensors may include a throttle inlet pressure (TIP) sensor for estimating the throttle inlet pressure (TIP) and / or a throttle inlet temperature sensor for estimating the throttle air temperature (TCT) downstream of the throttle valve coupled in the intake passage. Reference is made below to the control system 17 for information about the various sensors 16 (various examples of which are described herein) and for sending control signals to a plurality of actuators 99. As an example, as described above, the sensors 16 may include pressure sensors, temperature sensors, and oxygen sensors located within the intake passage 28, the intake manifold 44, the exhaust passage 74, and the first scavenging manifold 79. Other sensors may include a throttle inlet pressure (TIP) sensor for estimating the throttle inlet pressure (TIP) and / or a throttle inlet temperature sensor for estimating the throttle air temperature (TCT) downstream of the throttle valve coupled in the intake passage. Figure 1B Additional system sensors and actuators are described in detail. As another example, actuators 99 may include fuel injectors, valves 63, 42, 54, 59, 32, 97, 76, and throttle 62. Actuators 99 may also include various camshaft timing actuators coupled to cylinder intake and exhaust valves (as described below with reference to Figure 1B Controller 12 may receive input data from various sensors, process the input data, and trigger actuators in response to the processed input data based on instructions or code programmed in a memory of controller 12 corresponding to one or more routines. Figure 6 An example control routine (e.g., method) is described. For example, adjusting the EGR flow from the second scavenging manifold 80 to the intake passage 28 may include adjusting the actuator of the first EGR valve 54 to adjust the amount of exhaust gas flowing from the second scavenging manifold 80 to the intake passage 28 upstream of the compressor 162. In another example, adjusting the EGR flow from the second scavenging manifold 80 to the intake passage 28 may include adjusting the actuator of the exhaust camshaft to adjust the opening timing of the second exhaust valve 6.

[0040] In this way, Figure 1AThe first exhaust manifold and the second exhaust manifold may be designed to direct the bleed portion and the scavenged portion of the exhaust gas, respectively. The first exhaust manifold 84 may direct the bleed pulse of the exhaust gas to the dual-stage turbine 164 via the first manifold portion 81 and the second manifold portion 85, while the first scavenging manifold 79 may direct the scavenged portion of the exhaust gas to the intake passage 28 via one or more of the air passage 83, the second scavenging manifold 80, and the first EGR passage 50 and the second EGR passage 58 and / or to the exhaust passage 74 downstream of the dual-stage turbine 164 via the scavenging manifold bypass passage 98. For example, the first exhaust valve 8 directs the blown portion of the exhaust gas through the first exhaust manifold 84 to the dual-stage turbine 164 and both the first emission control device 70 and the second emission control device 72, while the second exhaust valve 6 directs the scavenging portion of the exhaust gas through the first scavenging manifold 79 and to the intake passage 28 via the second scavenging manifold 80 and one or more EGR passages, or to the exhaust passage 74 and the second emission control device 72 via the scavenging manifold bypass passage 98.

[0041] It should be noted that although Figure 1A The engine 10 is shown to include each of the first EGR passage 50, the second EGR passage 58, the scavenging manifold bypass passage 98, and the flow passage 30, but in alternative embodiments, the engine 10 may include only a portion of these passages. For example, in one embodiment, the engine 10 may include only the first EGR passage 50 and the scavenging manifold bypass passage 98, but not the second EGR passage 58 and the flow passage 30. In another embodiment, the engine 10 may include the first EGR passage 50, the second EGR passage 58, and the scavenging manifold bypass passage 98, but not the flow passage 30. In yet another embodiment, the engine 10 may include the first EGR passage 50, the flow passage 30, and the scavenging manifold bypass passage 98, but not the second EGR passage 58. In some embodiments, the engine 10 may not include the electric compressor 60. In other embodiments, the engine 10 may include Figure 1A All or only a portion of the sensors shown.

[0042] Reference now Figure 1B , which shows a partial view of a single cylinder of an internal combustion engine 10 that may be installed in a vehicle 100. Figure 1A Components introduced in the previous section are indicated by the same reference numerals and are not reintroduced. Engine 10 is depicted having a combustion chamber (cylinder) 130, a coolant sleeve 114, and a cylinder wall 132 in which a piston 136 is disposed and connected to a crankshaft 140. Combustion chamber 130 is shown communicating with intake passage 146 and exhaust passage 148 via respective intake valve 152 and exhaust valve 156. As previously described in Figure 1AAs described in , each cylinder of engine 10 can exhaust combustion products along two pipes. In the depicted view, exhaust passage 148 represents a first exhaust flow passage (e.g., air passage) (such as Figure 1A 86 ), while the second exhaust runner is not visible in this view.

[0043] As previously in Figure 1A As also described in detail in , each cylinder of the engine 10 may include two intake valves and two exhaust valves. In the depicted view, the intake valve 152 and the exhaust valve 156 are positioned in the upper region of the combustion chamber 130. The intake valve 152 and the exhaust valve 156 may be controlled by the controller 12 using a corresponding cam actuation system including one or more cams. The cam actuation system may utilize one or more of a cam profile switching system (CPS), a variable cam timing (VCT), a variable valve timing (VVT), and / or a variable valve lift (VVL) system to change the valve operation. In the depicted example, each intake valve 152 is controlled by an intake cam 151, and each exhaust valve 156 is controlled by an exhaust cam 153. The intake cam 151 may be actuated via the intake valve timing actuator 101 according to the set intake valve timing and exhaust valve timing, respectively, and the exhaust cam 153 may be actuated via the exhaust valve timing actuator 103. In some examples, the intake valve and exhaust valve can be deactivated via intake valve timing actuator 101 and exhaust valve timing actuator 103, respectively. For example, the controller can send a signal to exhaust valve timing actuator 103 to deactivate exhaust valve 156 so that it remains closed and does not open at its set timing. The positions of intake valve 152 and exhaust valve 156 can be determined by valve position sensors 155 and 157, respectively. As described above, in one example, all exhaust valves of each cylinder can be controlled on the same exhaust camshaft. In this way, the timing of both the scavenging (second) exhaust valve and the exhaust (first) exhaust valve can be adjusted together via one camshaft, but they can each have different timings relative to each other. In another example, the scavenging exhaust valve of each cylinder can be controlled on the first exhaust camshaft, and the exhaust exhaust valve of each cylinder can be controlled on a different second exhaust camshaft. In this way, the valve timing of the scavenging valve and the exhaust valve can be adjusted separately from each other. In alternative embodiments, the cam(s) or valve timing system for the scavenging exhaust valves and / or blowdown exhaust valves may employ cams in a cam system, an electro-hydraulic system on the scavenging valves, and / or electro-mechanical valve lift control on the scavenging valves.

[0044] For example, in some embodiments, the intake valve and / or the exhaust valve may be controlled via electric valve actuation. For example, cylinder 130 may alternatively include an intake valve controlled via electric valve actuation and an exhaust valve controlled via cam actuation including a CPS system and / or a VCT system. In other embodiments, the intake valve and the exhaust valve may be controlled by a common valve actuator (or actuation system) or a variable valve timing actuator (or actuation system).

[0045] In one example, the intake cam 151 includes separate and distinct cam lobes that provide a different valve profile (e.g., valve timing, valve lift, duration, etc.) for each of the two intake valves of the combustion chamber 130. Similarly, the exhaust cam 153 may include separate and distinct cam lobes that provide a different valve profile (e.g., valve timing, valve lift, duration, etc.) for each of the two exhaust valves of the combustion chamber 130. In another example, the intake cam 151 may include a common lobe or similar lobes that provide substantially similar valve profiles for each of the two intake valves.

[0046] Furthermore, different cam profiles for different exhaust valves can be used to separate exhaust gas that is exhausted at low cylinder pressure from exhaust gas that is exhausted at exhaust pressure. For example, a first exhaust cam profile can open a first exhaust valve (e.g., a blow-off valve) from a closed position just before BDC (bottom dead center) of a power stroke of the combustion chamber 130, and close the same exhaust valve well before top dead center (TDC) to selectively exhaust blow-off gas from the combustion chamber. Additionally, a second exhaust cam profile can be positioned to open a second exhaust valve (e.g., a scavenging valve) from a closed position before the midpoint of the exhaust stroke, and close it after TDC to selectively exhaust the scavenging portion of the exhaust gas.

[0047] Thus, the timing of the first and second exhaust valves can isolate the cylinder blow-off gases from the scavenging portion of the exhaust, while during the positive valve overlap between the intake valve and the scavenging exhaust valve, any residual exhaust in the clearance volume of the cylinder can be purged with fresh intake air blow-through. By flowing a first portion of the exhaust gas leaving the cylinder (e.g., higher pressure exhaust) to the turbine(s) and higher pressure exhaust passages, and flowing a second portion of the subsequent exhaust gas (e.g., lower pressure exhaust) and blow-through air to the compressor inlet, the efficiency of the engine system is increased. Turbine energy recovery can be enhanced, and engine efficiency can be increased via increased EGR and reduced knock.

[0048] continue Figure 1B , exhaust gas sensor 126 is shown coupled to exhaust passage 148. Sensor 126 may be located at one or more emission control devices such as Figure 1ASensor 126 may be selected from a variety of suitable sensors for providing an indication of exhaust air-fuel ratio, such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen sensor), a two-state oxygen sensor or EGO (as shown), HEGO (heated EGO), NOx, HC or CO sensor. Downstream emission control devices may include one or more of a TWC, a NOx trap, a GPF, various other emission control devices, or combinations thereof.

[0049] Exhaust temperature may be estimated by one or more temperature sensors (not shown) positioned in exhaust passage 148. Alternatively, exhaust temperature may be inferred based on engine operating conditions such as speed, load, air / fuel ratio (AFR), spark retard, etc.

[0050] Cylinder 130 can have a compression ratio, which is the ratio of volumes when piston 136 is at BDC to at TDC. Typically, the compression ratio is in the range of 9:1 to 10:1. However, in some examples, such as where a different fuel is used, the compression ratio may be increased. For example, this may occur when a higher octane fuel or a fuel with a higher latent enthalpy of vaporization is used. If direct injection is used, the compression ratio may also be increased due to its effect on engine knock.

[0051] In some embodiments, each cylinder of engine 10 may include spark plug 92 for initiating combustion. Under select operating modes, ignition system 188 can provide an ignition spark to combustion chamber 130 via spark plug 92 in response to spark advance signal SA from controller 12. However, in some embodiments, spark plug 92 may be omitted, such as where engine 10 may initiate combustion by auto-ignition or by injection of fuel (as is the case with some diesel engines).

[0052] In some embodiments, each cylinder of engine 10 may be configured with one or more fuel injectors for providing fuel thereto. As a non-limiting example, cylinder 130 is shown including one fuel injector 66. Fuel injector 66 is shown coupled directly to combustion chamber 130 for injecting fuel directly therein in proportion to the pulse width of signal FPW received from controller 12 via electronic driver 168. In this manner, fuel injector 66 provides what is known as direct injection of fuel into combustion chamber 130 (hereinafter also referred to as "DI"). Figure 1BInjector 66 is shown as a side injector, it may also be positioned on top of the piston, such as near spark plug 92. Due to the lower volatility of some alcohol-based fuels, this location may increase mixing and combustion when the engine is operated on alcohol-based fuels. Alternatively, the injector may be positioned on top and near the intake valve to increase mixing. In an alternative embodiment, injector 66 may be a port injector that provides fuel into the intake port upstream of cylinder 130.

[0053] Fuel may be delivered to fuel injector 66 from a high pressure fuel system 180 including a fuel tank, a fuel pump, and a fuel rail. Alternatively, fuel may be delivered at a lower pressure by a single-stage fuel pump, in which case the timing of direct fuel injection may be more limited during the compression stroke than when a high pressure fuel system is used. In addition, although not shown, the fuel tank may have a pressure sensor that provides a signal to controller 12. The fuel tanks in fuel system 180 may hold fuels with different fuel qualities (such as different fuel components). These differences may include different alcohol content, different octane ratings, different heats of vaporization, different fuel blends, and / or combinations thereof, etc. In some embodiments, fuel system 180 may be coupled to a fuel vapor recovery system that includes a canister for storing refueling and daytime fuel vapors. When the purge condition is met, fuel vapors may be purged from the canister to the engine cylinders during engine operation. For example, the purge vapors may be naturally drawn into the cylinders via the first intake passage at or below atmospheric pressure.

[0054] Engine 10 may be controlled at least partially by controller 12 and by input from a vehicle operator 113 via an input device 118, such as accelerator pedal 116. Input device 118 sends a pedal position (PP) signal to controller 12. Controller 12 may also provide a signal to the vehicle operator 113 to determine the pedal position (PP). Figure 1B1 is shown as a microcomputer that includes a microprocessor unit (CPU) 102, input / output ports (I / O) 104, an electronic storage medium for executable programs and calibration values, shown in this particular example as a read-only memory (ROM) 106, a random access memory (RAM) 108, a keep alive memory (KAM) 110, and a data bus. The storage medium read-only memory 106 is capable of being programmed with computer readable data representing instructions executable by the microprocessor 102 for performing the methods and routines described below, as well as other variants that are anticipated but not specifically listed. Controller 12 may receive various signals from sensors coupled to engine 10, including, in addition to those previously discussed, a measurement of intake mass air flow (MAF) from mass air flow sensor 48; engine coolant temperature (ECT) from temperature sensor 112 coupled to coolant sleeve 114; a surface ignition sensing signal (PIP) from a Hall effect sensor 120 (or other type) coupled to crankshaft 140; throttle position (TP) from a throttle position sensor; an absolute manifold pressure signal (MAP) from MAP sensor 122; cylinder AFR from EGO sensor 126; and abnormal combustion from a knock sensor and a crankshaft acceleration sensor. Engine speed signal RPM may be generated by controller 12 from signal PIP. Manifold pressure signal MAP from a manifold pressure sensor, such as MAP sensor 122, may be used to provide an indication of vacuum or pressure in the intake manifold.

[0055] Based on input from one or more of the above mentioned sensors, controller 12 may regulate one or more actuators such as fuel injector 66, throttle 62, spark plug 92, intake / exhaust valves and cams, etc. The controller may receive input data from the various sensors, process the input data, and trigger the actuators in response to the processed input data based on instructions or code programmed therein corresponding to one or more routines.

[0056] In some examples, vehicle 100 may be a hybrid vehicle having multiple torque sources available to one or more wheels 160. In other examples, vehicle 100 is a conventional vehicle having only an engine, or an electric vehicle having only (one or more) electric machines. Figure 1BIn the example shown, the vehicle 100 includes an engine 10 and an electric motor 161. The electric motor 161 may be a motor or a motor / generator, and therefore may also be referred to as an electric motor in this article. When one or more clutches 166 are engaged, the crankshaft 140 of the engine 10 and the electric motor 161 are connected to the wheels 160 via a transmission 167. In the example shown, the first clutch 166 is disposed between the crankshaft 140 and the electric motor 161, and the second clutch 166 is disposed between the electric motor 161 and the transmission 167. The controller 12 may send a signal to the actuator of each clutch 166 to engage or disengage the clutch so as to connect or disconnect the crankshaft 140 with the electric motor 161 and the components connected to the electric motor 161, and / or connect or disconnect the electric motor 161 with the transmission 167 and the components connected to the transmission 167. The transmission 167 may be a gearbox, a planetary gear system, or another type of transmission. The powertrain may be configured in various ways, including parallel, series, or series-parallel hybrid vehicles.

[0057] The electric machine 161 receives electrical power from the traction battery 170 to provide torque to the wheels 160. The electric machine 161 may also operate as a generator to provide electrical power to charge the battery 170, such as during a braking operation.

[0058] Next go to Figure 2 , shows a partial schematic diagram of a split exhaust system 200 including a scavenging manifold with dual air passages. For example, the split exhaust system 200 may be Figure 1A The separate exhaust system of FIG. 1 is identical to that of FIG. 1 , and therefore like parts are numbered the same and may not be reintroduced. Figure 2 As shown and referenced above Figure 1A As described above, the first scavenging manifold 79 can be scavenged from the exhaust valve (eg, Figure 1A The first scavenging exhaust valve 79 (SV 6) receives exhaust and / or blow-through air, and the second scavenging manifold 80 may receive exhaust and / or blow-through air from the scavenging exhaust valve via the second exhaust runner 82 and the air passage 83. Therefore, although the first scavenging manifold 79 and the second scavenging manifold 80 are not directly coupled, the air passage 83 and the second exhaust runner 82 fluidly couple the first scavenging manifold 79 and the second scavenging manifold 80.

[0059] In addition, the bleed manifold 84 (the second manifold portion 85 of which is Figure 2 ) can be exhausted from the blow-off exhaust valve (eg, Figure 1A The exhaust valve 8) receives the exhaust gas. Figure 2 As shown, SV1 and BV1 correspond to the scavenging exhaust valve and the blow-off exhaust valve of the first cylinder, respectively, SV2 and BV2 correspond to the scavenging exhaust valve and the blow-off exhaust valve of the second cylinder, respectively, and so on.

[0060] like Figure 2As shown, the first scavenging manifold 79 and the second scavenging manifold 80 are arranged substantially parallel to each other, but are spaced apart from each other. Figure 2 As shown in the exemplary orientation of , the first scavenging manifold 79 and the second scavenging manifold 80 may be arranged on opposite sides of the exhaust runner 86, wherein the first scavenging manifold 79 is arranged above the exhaust runner 86 and the second scavenging manifold 80 is arranged below the exhaust runner 86. In this way, the first scavenging manifold 79 and the second scavenging manifold 80 may be displaced from each other in the vertical direction and the lateral direction. Each exhaust runner 82 extends between the corresponding scavenging exhaust valve and the first scavenging manifold 79 and is coupled to the corresponding scavenging exhaust valve and each of the first scavenging manifold 79. In addition, each exhaust runner 83 extends between the second scavenging manifold 80 and the corresponding exhaust runner 82 that is closer to the corresponding scavenging exhaust valve than the first scavenging manifold 79 and is coupled to each of the corresponding exhaust runner 82 and the second scavenging manifold 80 at a position along the exhaust runner 82. In one example, as Figure 2 As shown, each air passage 83 may be coupled to its corresponding exhaust runner 82 at a location on the exhaust runner 82 that is between the corresponding scavenging exhaust valve and a midpoint of the exhaust runner 82 .

[0061] The inlet (e.g., first end) 83a of each air passage 83 is directly coupled to one exhaust runner 82, proximate to the corresponding scavenging exhaust valve, and the outlet (e.g., second end) 83b of each air passage 83 is directly coupled to the second scavenging manifold 80. The outlet of each air passage is spaced apart from the outlet of the adjacent air passage so that the outlet of the air passage 83 is positioned and coupled along the length of the second scavenging manifold 80. The diameter of each air passage 83, which may be constant over its entire length, is smaller than each of the diameters of the exhaust runner 82, the first scavenging manifold 79, and the second scavenging manifold 80. In addition, the diameter of the second scavenging manifold 80 may be smaller than the diameter of the first scavenging manifold 79. In a non-limiting example, the diameter of the air passage 83 may be approximately 9 mm, the diameter of the first scavenging manifold 80 may be approximately 21 mm, and the diameter of the second scavenging manifold 80 may be approximately 18 mm. In an alternative example, the diameter of the air passage 83 may be in the range of 8 mm to 10 mm, the diameter of the first scavenging manifold 80 may be in the range of 20 mm to 22 mm, and the diameter of the second scavenging manifold 80 may be in the range of 17 mm to 19 mm. The smaller diameter of the air passage 83 (and the second scavenging manifold 80) may cause a first portion of the gas (e.g., exhaust and blow-through air) flowing through the second exhaust runner 82 to the first scavenging manifold 79 to be greater than a second remaining portion of the gas flowing through the second exhaust runner 82 to the second scavenging manifold 80 via the air passage 83. Thus, the smaller diameter of the air passage 83 may be used to restrict the flow of gas to the second scavenging manifold 80 and, therefore, to the compressor (e.g., Figure 1AHowever, due to the gas composition gradient within the second exhaust runner, the relatively close location of the inlet of each air passage 83 along the second exhaust runner 82 to each scavenging exhaust valve may cause the blow-through air to flow preferentially through the air passage 83 (rather than to the first scavenging manifold 79), as will be described below with reference to Figure 4 and Figure 5 Further described. For example, the inlet of each air passage 83 is positioned closer to the scavenging exhaust valve than the coupling position between the second exhaust runner 82 and the first scavenging manifold 79. Therefore, although the second part of the gas may be smaller in amount than the first part of the gas, it may contain a larger proportion of the blow-through air than the first part of the gas. In addition, the second scavenging manifold 80 may be arranged closer to the scavenging exhaust valve than the first scavenging manifold 79. Since the second scavenging manifold 80 is closer to the scavenging valve relative to the first scavenging manifold 79, and the air passage 83 and the second scavenging manifold 80 are smaller in diameter relative to the exhaust runner 82 and the first scavenging manifold 79, respectively, the air passage 83 and the second scavenging manifold 80 can hold a smaller volume of gas than the exhaust runner 82 and the first scavenging manifold 79.

[0062] Figure 2 An example configuration with relative positioning of various components is shown. If it is shown that they are in direct contact or directly coupled to each other, then at least in one example, such elements may be referred to as being in direct contact or directly coupled, respectively. Similarly, elements that are shown to be adjacent or neighboring to each other may be referred to as being adjacent or neighboring to each other, respectively, at least in one example. As an example, components that are in coplanar contact with each other may be referred to as being in coplanar contact. As another example, components that are positioned separately from each other and only have space without other components in between may be referred to as such in at least one example. As another example, elements that are shown above / below each other, on the sides opposite to each other, or on the left / right of each other relative to each other may be referred to as such relative to each other. In addition, as shown in the figure, in at least one example, the topmost element or the topmost point of an element may be referred to as the "top" of a component, and the bottommost element or the bottommost point of an element may be referred to as the "bottom" of a component. As used herein, top / bottom, upper / lower, above / below may be relative to the vertical axis of the figure and used to describe the positioning of the elements of the figure relative to each other. Thus, in one example, the element shown above other elements is positioned vertically above other elements. As yet another example, the shapes of elements shown within a figure may be referred to as having those shapes (e.g., such as circular, straight, flat, curved, rounded, chamfered, inclined, etc.). Furthermore, in at least one example, elements shown as intersecting each other may be referred to as intersecting elements or intersecting each other. Furthermore, in one example, an element shown within another element or shown outside another element may be referred to as such.

[0063] Now go to Figure 3, diagram 300 depicts example valve timing with respect to piston position for an engine cylinder including four valves (two intake valves and two exhaust valves), such as described above with reference to Figure 1A to Figure 1B Although not every point is labeled with a numerical value, Figure 3 The examples are drawn substantially to scale. Therefore, relative differences in timing can be estimated by the drawing dimensions. However, other relative timings may be used if desired.

[0064] continue Figure 3 , the cylinder is configured to receive intake air via two intake valves and exhaust air via a first exhaust valve (e.g., such as Figure 1A The first or bleed exhaust valve 8 shown in FIG. 1 ) discharges a first bleed portion of the exhaust gas to the turbine inlet, via a second exhaust valve (e.g., such as Figure 1A The second or scavenging exhaust valve 6 shown in FIG. 6 discharges a second scavenging portion of the exhaust gas into the intake passage, and provides unburned blow-by air to the intake passage via the second exhaust valve. By adjusting the timing of the opening and / or closing of the second exhaust valve with the opening and / or closing of the two intake valves, residual exhaust gas in the cylinder clearance volume can be scavenged and recirculated as EGR together with fresh intake blow-by air. In addition, under selected conditions, such as when turbine power is low (e.g., during relatively low engine speeds / high engine loads) or when the compressor inlet temperature is high (e.g., during relatively high engine speeds / high engine loads), the second scavenging portion can be directed to the exhaust passage downstream of the turbine via the scavenging manifold bypass passage, while the blow-by air is directed to the intake passage, as described herein with respect to Figure 6 as further described.

[0065] Graph 300 shows the engine position along the X axis of crank angle (CAD). Curve 302 depicts the piston position (along the Y axis) relative to the top dead center (TDC) and / or the bottom dead center (BDC) and the four strokes of the engine cycle (intake, compression, power and exhaust). During the intake stroke, the exhaust valve is usually closed and the intake valve is open. Air is introduced into the cylinder via the corresponding intake passage, and the cylinder piston moves to the bottom of the cylinder to increase the volume in the cylinder. The position of the piston near the bottom of the cylinder and at the end of its stroke (e.g., when the combustion chamber is at its maximum volume) is generally referred to as the bottom dead center (BDC) by those skilled in the art. During the compression stroke, the intake and exhaust valves are closed. The piston moves toward the cylinder head to compress the air in the combustion chamber. The point at which the piston is at the end of its stroke (e.g., when the combustion chamber is at its minimum volume) and closest to the cylinder head is generally referred to as the top dead center (TDC) by those skilled in the art. In the process referred to herein as injection, fuel is introduced into the combustion chamber. In a process referred to herein as ignition, the injected fuel is ignited by a known ignition device (such as a spark plug), resulting in combustion. During the expansion stroke, the expanding gases push the piston back to BDC. The crankshaft converts this piston motion into a rotational torque of the rotating shaft. During the exhaust stroke, in a conventional design, the exhaust valve is opened to release the residual combustion air-fuel mixture to the corresponding exhaust passage, and the piston returns to TDC. In this specification, the second exhaust (scavenging) valve may be opened after the start of the exhaust stroke and remain open until after the end of the exhaust stroke, while the first exhaust (bleed) valve is closed and the intake valve is opened to flush out the residual exhaust with blow-in air.

[0066] Curve 304 depicts a first intake valve timing, lift, and duration of a first intake valve (Int_1), while curve 306 depicts a second intake valve timing, lift, and duration of a second intake valve (Int_2), both of which are coupled to an intake passage of an engine cylinder. Curve 308 depicts a first exhaust runner (e.g., Figure 1A The first exhaust runner 86 of the engine is coupled to a first exhaust manifold (eg, Figure 1A The first exhaust valve (Exh_1, which may correspond to the exhaust manifold shown in FIG. Figure 1A , while curve 310 depicts example exhaust valve timing, lift, and duration for a first or bleed exhaust valve 8 shown in FIG. 1 ... Figure 1A The second exhaust runner 82 of the embodiment is coupled to the first scavenging manifold and the second scavenging manifold (eg, Figure 1A The second exhaust valve (Exh_2, which may correspond to the first scavenging manifold 79 and the second scavenging manifold 80) shown in FIG. Figure 1A6). As previously described, the first exhaust manifold connects the first exhaust valve to the inlet of the turbine in the turbocharger, and the first scavenging manifold connects the second exhaust valve to the exhaust passage downstream of the turbocharger turbine. The air passage in the second exhaust runner (e.g., Figure 1A 83) via a second scavenging manifold (eg, Figure 1A The second scavenging manifold 80) and the EGR passage connect the second exhaust valve to the intake passage. The first exhaust manifold can be separated from the first scavenging manifold and the second scavenging manifold, and the first scavenging manifold and the second scavenging manifold can be coupled by the air passage fluid, as described above.

[0067] In the depicted example, the first intake valve and the second intake valve are fully opened from a closed position at a common timing (curves 304 and 306) starting near the intake stroke TDC just after CAD2 (e.g., at or just after the intake stroke TDC), and closed after the subsequent compression stroke begins past CAD3 (e.g., after BDC). In addition, when fully open, both intake valves may be open for the same duration D1 with the same valve lift amount L1. In other examples, the two valves may be operated at different timings by adjusting the phase, lift, or duration based on engine conditions.

[0068] Turning now to the exhaust valves, the timing of the opening and closing of the first exhaust valve is staggered relative to the timing of the opening and closing of the second exhaust valve. Specifically, in the engine cycle, the first exhaust valve opens from a closed position at a first timing (curve 308), which is earlier in the engine cycle than the timing of the second exhaust valve opening from a closed position (curve 310). Specifically, the first timing of opening the first exhaust valve is between TDC and BDC of the power stroke, before CAD1 (e.g., before BDC of the exhaust stroke), while the timing of opening the second exhaust valve is just after BDC of the exhaust stroke, after CAD1 but before CAD2. The first exhaust valve (curve 308) closes before the end of the exhaust stroke, and the second exhaust valve (curve 310) closes after the end of the exhaust stroke. Therefore, the second exhaust valve remains open to slightly overlap with the opening of the intake valve.

[0069] In detail, the first exhaust valve (curve 308) may be fully opened from a closed position before the start of the exhaust stroke (e.g., between 90 degrees and 40 degrees before BDC), maintained fully open during a first portion of the exhaust stroke, and may be fully closed before the end of the exhaust stroke (e.g., between 50 degrees and 0 degrees before TDC) to collect the blow-off portion of the exhaust pulse. The second exhaust valve (curve 310) may be fully opened from a closed position just after the start of the exhaust stroke (e.g., between 40 degrees and 90 degrees past BDC), maintained open during a second portion of the exhaust stroke, and may be fully closed after the start of the intake stroke (e.g., between 20 degrees and 70 degrees after TDC) to exhaust the scavenged portion of the exhaust. In addition, as Figure 3 As shown, the second exhaust valve and intake valve may have positive overlap phase (e.g., from between 20 degrees before TDC to 40 degrees after TDC until between 40 degrees and 90 degrees after TDC) to allow EGR to be purged. This cycle in which all four valves are operable may occur again based on engine operating conditions, as described below with reference to Figure 6 as further described.

[0070] Furthermore, the first exhaust valve (plot 308) may be opened with a first amount of valve lift, L2, while the second exhaust valve may be opened with a second amount of valve lift, L3 (plot 310), where L3 is less than L2. Additionally, the first exhaust valve may be opened for a duration, D2, at a first timing, while the second exhaust valve may be opened for a duration, D3, where D3 is less than D2. It should be appreciated that in alternative embodiments, the two exhaust valves may have the same amount of valve lift and / or the same duration of opening while opening at different phase timings.

[0071] In this way, by using staggered valve timing, it is possible to increase engine efficiency and power by separating the exhaust gas released at a higher pressure (e.g., the exhaust gas expanded in the cylinder) from the residual exhaust gas at a low pressure (e.g., the exhaust gas remaining in the cylinder after the exhaust gas is blown) into different manifolds. By delivering the low-pressure residual exhaust gas to the compressor inlet as EGR together with the blow-in air (via the EGR passage and the second scavenging manifold), the combustion chamber temperature can be reduced, thereby reducing the occurrence of knock and the amount of spark retardation at the maximum torque timing. In addition, since the exhaust gas at the end of the stroke is directed to the downstream of the turbine or upstream of the compressor (both of which are at a lower pressure), it is possible to minimize the exhaust pumping loss to improve engine efficiency.

[0072] Thus, the exhaust gas can be used more efficiently than simply directing all of the exhaust gas from the cylinders through a single common exhaust passage to the turbocharger turbine. In this way, several advantages can be achieved. For example, the average exhaust pressure supplied to the turbocharger can be increased by separating and directing the bleed air pulses to the turbine inlet to increase the turbocharger output. In addition, fuel economy can be increased because the blow-off air is not sent to the catalyst, but is directed to the compressor inlet, and therefore, excess fuel may not be injected into the exhaust gas to maintain the stoichiometric ratio.

[0073] Now go to Figure 4 , which shows a diagram 400 and engine positions, where the diagram 400 shows the exhaust valve (eg, Figure 1A The second exhaust valve 6) is coupled to the exhaust flow passage (eg, Figure 2 82) changes based on the distance from the scavenging exhaust valve (SV). The X-axis represents the distance from the SV, where the distance increases from left to right. The arrows mark the exhaust runners that couple to the second scavenging manifold (e.g., Figure 1A and Figure 2 The air passage (for example, Figure 1A and Figure 2 The position of the air passage 83) is via the first scavenging manifold (for example, Figure 1A The first scavenging manifold 79) to the scavenging manifold bypass passage ( Figure 1A SMBP 98). The Y-axis represents the relative gas composition in the exhaust runner at each engine location, which is labeled as crank angle degrees after TDC (ATDC) of the intake stroke of the cylinder. The relative gas composition ranges from combustion gases (e.g., burned exhaust) to fresh air (or a mixture of fresh air and unburned fuel), with dashed line 418 representing a 1:1 mixture of combustion gases and fresh air. Therefore, the gas above dashed line 418 has more fresh air than combustion gases, where the amount of fresh air increases upward along the Y-axis (e.g., in the direction of the arrow), and the gas below dashed line 418 has more combustion gases than fresh air, where the amount of combustion gases increases downward along the Y-axis.

[0074] At -110 degrees ATDC intake (e.g., during the exhaust stroke, 110 crank angle degrees before TDC of the intake stroke of the cylinder), the exhaust runner contains combustion gases throughout its entire length as shown by curve 402. When the SV is closed before -110 degrees ATDC, the combustion gases may be from a previous combustion event. At -110 degrees ATDC, the SV is open (for representative valve timing, see Figure 5) and the intake valve (or valves) remain closed; therefore, fresh air does not enter the cylinder, and residual combustion gases (e.g., the scavenging portion) from the combustion event can begin to be discharged through the SV and into the exhaust runner.

[0075] At -70 degrees ATDC intake (e.g., 70 degrees crank angle before TDC of the intake stroke, also during the exhaust stroke), the SV remains open and the intake valve remains closed. The scavenged portion of the exhaust continues to flow through the SV and into the exhaust runner, resulting in the exhaust runner being full of combustion gases (curve 404). Depending on the position of the SMBV in the SMBP and the BTCC valve in the EGR passage (e.g., Figure 1A In one embodiment, when the SMBV is closed and the BTCC valve is open, the scavenging portion may flow to the compressor inlet as EGR instead of flowing to the exhaust passage via the SMBP. In another example, when the SMBV is open and the BTCC valve is closed, the scavenging portion may flow to the exhaust passage via the SMBP instead of flowing to the compressor inlet. In yet another example, when both the SMBV and the BTCC valve are (at least partially) open, a first portion of the scavenging portion may flow to the exhaust passage via the SMBP, and a second portion of the scavenging portion may flow to the compressor inlet via the air passage and the EGR passage. However, in this example, the first portion may be larger than the second portion because the air passage of the scavenging manifold with the air passage has a smaller diameter than the exhaust passage, as described above with reference to Figure 2 Explained.

[0076] At -30 degrees ATDC intake, the intake valve opens. Fresh air begins to enter the cylinder, but has not yet reached the SV which remains open. Therefore, the gas composition in the exhaust runner (curve 406) maintains the combustion gas from the scavenged portion of the exhaust as well as the combustion gas from the previous combustion event, such as due to reflow, as will be further described below.

[0077] At 10 degrees ATDC (curve 408), both the intake valve and the SV remain open. Therefore, there is a strong blow-through, where fresh air flows through the intake valve and the SV to the exhaust runner. For example, at 10 degrees ATDC, the intake valve and the SV may have a maximum overlap, such as Figure 5As shown in the example of . The fresh blow-off air pushes the combustion gases further along the exhaust runner toward the SMBV. The gas composition within the exhaust runner begins to have a gradient between the combustion gases at the far end (e.g., toward the SMBP) and the fresh air at the SV, as shown by curve 408. The shorter the distance from the SV, the greater the proportion of fresh air in the exhaust runner. At the location of the air duct, the gas is almost entirely composed of fresh air. Therefore, the fresh air can flow mainly through the air duct to the second scavenging manifold (and then to the inlet of the compressor), while the combustion gases can flow mainly to the SMBP via the first scavenging manifold.

[0078] At 180 degrees ATDC (curve 410), the gradients of fresh air and combustion gases have shifted so that the composition of the gas in the exhaust runner transitions through dashed line 418 (representing equal portions of fresh air and combustion gases) at a greater distance from the SV than at 10 degrees ATDC (curve 408). However, while the intake valve remains open, the SV closes at 180 degrees ATDC. Therefore, fresh air no longer flows from the SV to the exhaust runner. As shown by curve 410, the gas composition may be entirely fresh air at the air passage to the second scavenging manifold.

[0079] Gases (e.g., fresh air, combustion gases, or a mixture thereof) may flow between the exhaust runner and the compressor inlet (via the airway and the second scavenging manifold) and between the exhaust runner and the exhaust passage (via the first scavenging manifold and the SMPB) based on the pressures at the exhaust runner, the compressor inlet, and the exhaust passage. For example, if the SMBV is open and the pressure in the exhaust passage is higher than the pressure in the exhaust runner, the combustion gases may flow back from the exhaust passage through the SMBP and back to the exhaust runner via the first scavenging manifold. This backflow may shift the gas composition gradient back toward the (closed) SV, as shown by curve 412 (270 degrees ATDC intake). In addition, the pressure at the compressor inlet may be lower than the pressure in the exhaust passage, allowing fresh air at the airway to flow from the exhaust runner to the second scavenging manifold and to the compressor inlet through the EGR passage when the BTCC valve is open.

[0080] At 360 degrees ATDC (curve 414), where both the SMBV and BTCC valves are at least partially open, exhaust gas recirculation through the SMBP and fresh air consumption by the compressor further shifts the gas gradient toward the (closed) SV and the airway. At -270 degrees ATDC (curve 416), 270 crank angle degrees before TDC of the intake stroke of the next engine cycle, the gradient between fresh air and combustion gases becomes steeper than at 360 degrees ATDC (curve 414), where the transition between predominantly fresh air and predominantly combustion gases becomes closer to the airway. At -110 degrees ATDC, all fresh air has been consumed by the compressor, leaving combustion gases in the exhaust runner (curve 402).

[0081] Notice, Figure 4 The engine positions given in the examples of are exemplary in nature. In other examples, such as when the timing of the SV and (one or more) intake valves are different, the gas composition at a given engine position may be different (e.g., shifted).

[0082] and Figure 4 provides relative gas compositions within the exhaust runners (and at the airway to the second scavenging manifold) for several example engine locations of interest, Figure 5 5 is an example graph 500 showing how the gas composition at the airway (eg, the inlet of the airway 83 where the exhaust runners and airway are connected) changes based on the crank angle. Figure 5 , the piston position is shown in curve 502 (similar to Figure 3 The relative gas composition at the airway is shown in curve 504, the cylinder pressure is shown in curve 505, and the exhaust passage pressure is shown in curve 506 (e.g., Figure 1A ), the pressure in the exhaust passage 74 shown in ), the pressure of the first exhaust runner is shown in the dotted curve 507, the pressure of the second exhaust runner is shown in the solid curve 508, the compressor inlet pressure is shown in curve 510, the blowdown exhaust valve (BV) lift is shown in curve 512, the SV lift is shown in curve 514 and the intake valve lift is shown in curve 516. For all of the above, the X-axis represents the crank angle in degrees ATDC. The Y-axis represents the labeled parameters, where the values ​​increase from bottom to top except for curve 504, where the Y-axis varies from combustion gas to fresh air as labeled. The exhaust passage pressure (curve 506) refers to the pressure of the exhaust passage downstream of the first catalyst and upstream of the second catalyst (e.g., by Figure 1A The first exhaust runner pressure (curve 507) refers to the exhaust runner pressure that couples BV to the exhaust manifold (eg, Figure 1A and Figure 2 , and the second exhaust runner pressure (curve 508) refers to the exhaust runner that couples the SV to the first scavenging manifold (eg, Figure 1A and Figure 2 The pressure in the exhaust flow passage 82) is shown in FIG. Figure 4 As described by the dotted line 418, Figure 5 Dashed line 518 represents a 1:1 mixture of combustion gases and fresh air.

[0083] Diagram 500 shows a multi-cylinder engine system such as Figure 1A500 ), and corresponding example timings for the intake valve (curve 516) and exhaust valve (curve 512 and curve 514) coupled to the first cylinder. However, during the single engine cycle of the first cylinder, the other cylinders of the multi-cylinder engine system also undergo combustion, which includes exhausting combustion gases at staggered timing compared to the first cylinder of graph 500 . This results in pulses of higher exhaust pressure (curve 507) in the first exhaust runner throughout the engine cycle of the first cylinder. For example, when the BV opens between -270 degrees ATDC and -180 degrees ATDC (curve 512), the first exhaust runner pressure (curve 507) increases because the higher pressure cylinder (curve 505) is emptied into the blow-off exhaust manifold (note that the cylinder pressure curve has been clipped due to the high amplitude of the cylinder pressure relative to the other pressure curves). In addition, with the SMBV open, the exhaust runner is in fluid communication with the exhaust passage (via the SMBP and the first exhaust manifold) and the exhaust runners of the SVs coupled to the other cylinders (via the first exhaust manifold). Therefore, the second exhaust runner also experiences pressure pulses (curve 508), although their amplitude is smaller than the pulses experienced in the first exhaust runner (curve 507). On the other hand, the compressor inlet pressure (curve 510) remains relatively constant and lower than the exhaust pressure. As a result, gas can flow back from the exhaust passage through the SMBP to the first scavenging manifold, to the exhaust runner, through the gas passage to the second scavenging manifold, and back to the compressor inlet via the EGR passage.

[0084] When the SV is closed (e.g., between 70 degrees ATDC and -110 degrees ATDC later in the engine cycle), the return flow of exhaust gas from the exhaust passage to the first scavenging manifold and the flow of gas (EGR and blow-by air) from the second scavenging manifold to the compressor inlet causes the relative gas composition at the air passage (curve 504) to gradually change. For example, after the SV is closed during the intake stroke (e.g., at 70 degrees ATDC), the air passage is mainly fresh air. Throughout the compression stroke (e.g., 180 degrees ATDC to 360 degrees ATDC) and the power stroke (e.g., -360 degrees ATDC to -180 degrees ATDC later in the engine cycle), the relative amount of fresh air in the gas at the air passage decreases (and the relative amount of combustion gas at the air passage increases). Before the SV opens during the exhaust stroke, the air passage may contain combustion gas with little fresh air. When the SV is open (e.g., at -110 degrees ATDC), the scavenged portion of the exhaust leaves the SV to the exhaust runner. Therefore, the composition at the air passage maintains the combustion gas until the intake valve opens (eg, at -30 degrees ATDC) and the fresh blow-through air quickly replaces the combustion gas at the air passage.

[0085] In conclusion, Figure 4 The chart of 400 and Figure 5 Graph 500 shows how the gas composition gradients in the exhaust runners and the location of the runners to the second scavenging manifold promote primarily fresh air flow through the runners and primarily combustion gas flow through the SMBP. Thus, blow-through air may be provided to the compressor inlet rather than the exhaust passages, as fresh air may degrade the ability of the downstream catalyst to reduce NOx. In particular, selectively flowing blow-through air to the compressor inlet and combustion gas to the exhaust passages rather than flowing both EGR and blow-through air to the compressor inlet under restricted compressor flow conditions may be beneficial, as further described below.

[0086] Figure 6 A method for adjusting a BTCC valve (eg, Figure 1A The opening of the BTCC valve 54) and the SMBV (for example, Figure 1A Example method 600 for determining the opening of an SMBV 97. The method may be performed by a controller (e.g., Figure 1A The controller 12) is based on instructions stored in the memory of the controller and in conjunction with sensors from the engine system (such as those referenced above). Figure 1A to Figure 1B The sensors described (e.g. Figure 1A The controller may use engine actuators (eg, BTCC valve, SMBV) of the engine system to adjust engine operation according to the method described below.

[0087] Method 600 begins at 602 and includes estimating and / or measuring engine operating conditions. Engine operating conditions may include brake pedal position; accelerator pedal position; operator torque demand; ambient temperature and humidity; barometric pressure; engine speed; engine load; engine temperature; mass air flow (MAF); intake manifold pressure (MAP); oxygen content of intake air / exhaust at various points in the engine system; timing of cylinder intake and exhaust valves; positions of various valves of the engine system; temperature and / or load level of one or more emission control devices; pressure in the exhaust manifold, exhaust runners, exhaust passages, and / or intake passages; amount of fuel injected into engine cylinders; turbocharger speed; condensate formation at the turbocharger compressor; temperature at the turbocharger compressor inlet and / or outlet, etc.

[0088] At 604 , method 600 includes setting an intake valve (eg, Figure 1A The intake cam timing of the intake valves 2 and 4) and the scavenging exhaust valves (e.g. Figure 1A The second exhaust valve 6) and the blow-off exhaust valve (eg, Figure 1AThe exhaust cam timing of the first exhaust valve 8) is used for optimal fuel economy. For example, the timing of the exhaust valve and the intake valve can be set for the best achievable brake fuel consumption (BSFC) under the current engine operating conditions. In one example, as described above, this may include Figure 3 The timing shown sets the timing of the scavenging exhaust valve, the blowdown exhaust valve, and the intake valve of each cylinder. In some embodiments, the timing can be based on engine speed and load according to Figure 3 The timing shown slightly adjusts the timing of the exhaust and intake valves. For example, the intake timing can be adjusted to fully retarded at lighter engine loads, and the intake timing can be advanced when the engine is boost limited or requires increased blow-through to reduce knock. In another embodiment, the exhaust valve timing can be adjusted so that the exhaust valve opens earlier as the engine speed increases. Then, the exhaust valve timing can be retarded when the boost is reduced (for example, at low engine speed and high engine load conditions) or when the engine speed is high and the EGR temperature is greater than a threshold temperature.

[0089] At 606, it is determined whether EGR or blown combustion cooling (BTCC) is desired or currently enabled. Figure 1A 80 and the first EGR passage 50 shown in FIG. 5 ) deliver EGR and blow-air to the intake passage of the engine upstream of the turbocharger compressor. For example, if the engine load is above a threshold load, EGR and blow-air to the intake passage may be desired and enabled. In another example, if the BTCC hardware (e.g., BTCC valve and / or scavenging exhaust valve) of the engine is activated, EGR and blow-air may be enabled. For example, if the scavenging exhaust valve is operating (e.g., not deactivated) and the BTCC valve is open or at least partially open, it may be determined that the BTCC hardware is activated.

[0090] If BTCC is not desired, such as when the engine load is below a threshold load, the method continues to 608 to deactivate the scavenging exhaust valve and operate the engine without blow-off. For example, this may include maintaining the scavenging exhaust valve closed and sending exhaust gas from the engine cylinders to the exhaust passage only via the blow-off exhaust valve. As an example, the controller may send a valve actuator (e.g., Figure 1B The exhaust valve timing actuator 103 shown in FIG. 1 sends a deactivation signal to deactivate the SV of each cylinder. In addition, the method at 608 may include operating the engine without external EGR. The method then ends.

[0091] If EGR and blow-through are desired and / or BTCC hardware has been activated at 606, the method continues to 610 and includes adjusting BTCC valve opening (e.g., adjusting the position of the BTCC valve), scavenging exhaust valve (SV) timing, intake valve (IV) timing, and / or SMBV opening (e.g., adjusting the position of the SMBV) based on the desired blow-through and EGR flow, boost level (e.g., boost pressure downstream of the turbocharger compressor), and the current position and timing of each of the valves listed above. As an example, the BTCC valve may open in response to engine boost (e.g., when the turbocharger compressor is operating and causing MAP to be greater than atmospheric pressure). As another example, if more or less EGR flow or blow-through is desired via the second scavenging manifold and the EGR passage to the intake passage relative to currently estimated levels (e.g., as estimated based on the output of a pressure sensor and / or an oxygen sensor located in the first scavenging manifold and / or the second scavenging manifold), the controller may adjust the position or timing of one or more of the BTCC valve, SV, IV, and SMBV to achieve the desired EGR flow and blow-through air flow. For example, if an increase in EGR is desired, the controller may increase the opening of the BTCC valve, advance the SV timing, and / or reduce the opening of the SMBV. If, on the contrary, a decrease in EGR is desired, the controller may reduce the opening of the BTCC valve, retard the SV timing, and / or increase the opening of the SMBV. As another example, if an increase in blow-through air is desired, the controller may retard the SV timing, advance the IV timing, reduce the opening of the SMBV, and / or increase the opening of the BTCC valve. If reduced blow-by is desired, the controller may advance SV timing, retard IV timing, increase SMBV opening, and / or decrease BTCC valve opening. Additionally, adjusting valve position and timing at 610 may include adjusting valve position and / or timing relative to each other's position and timing.

[0092] In another example of the method at 610, the scavenging manifold pressure at certain SV timings may change the control of the BTCC valve, SMBV, and / or intake valve. For example, if the BTCC valve is closed and the desired scavenging manifold pressure is lower than the currently measured scavenging manifold pressure, the method may include opening or increasing the opening amount of the SMBV at 610 to reduce the scavenging manifold pressure. As another example, the SV timing may be adjusted based on the measured scavenging manifold pressure. In one example, in response to the measured scavenging manifold pressure being greater than the desired scavenging manifold pressure, the method may include delaying the SV timing to reduce the scavenging manifold pressure. The desired scavenging manifold pressure may be determined based on (e.g., according to) one or more of the intake manifold pressure, exhaust pressure, and / or boost conditions (e.g., whether the engine is boosted). In addition, in response to adjusting the SV timing based on the measured pressure and in response to the scavenging manifold pressure, the position of the BTCC valve and / or SMBV may be adjusted. For example, after adjusting the SV timing, the position of the SMBV may be adjusted (based on engine operating conditions) to maintain the scavenging manifold pressure at a desired scavenging manifold pressure, and the position of the BTCC valve may be adjusted to maintain the EGR flow at a desired EGR flow (e.g., based on engine operating conditions, such as engine load, knock, and compressor operating conditions such as temperature and speed).

[0093] The above-mentioned valve adjustment performed at 610 can be described as a baseline EGR and BTCC mode. However, other modes can be selected based on engine operating conditions. For example, if there are one or more restricted compressor flow conditions (such as satisfying one or more operating thresholds), the restricted compressor flow mode can be selected. Therefore, at 612, method 600 includes determining whether the restricted compressor flow condition is satisfied. The restricted compressor flow condition may result in a request to reduce the EGR flow to the compressor inlet. The restricted compressor flow condition may include a lower turbine power, wherein the turbine power is lower than a lower threshold (such as may occur during a relatively low engine speed / high load condition), and a higher compressor inlet temperature, wherein the compressor inlet temperature is higher than an upper threshold (such as may occur during a relatively high engine speed / high load condition). For example, a lower turbine power may refer to a speed of a turbocharger (such as a speed of a compressor and / or turbine of a turbocharger) that is less than or equal to a first lower threshold speed. A higher compressor inlet temperature may refer to a compressor inlet temperature greater than or equal to an upper threshold inlet temperature, wherein the upper threshold inlet temperature may be based on a temperature, above which degradation of one or more compressor components may occur. Additionally, a restricted compressor flow condition may exist when the turbocharger compressor speed is greater than or equal to a second higher threshold speed, which may be based on a speed above which compressor impeller degradation may occur. A restricted compressor flow condition or a request for EGR reduction at the compressor inlet may also occur when condensate formation at the compressor is above a threshold level (e.g., the amount or rate of condensate formation).

[0094] If the restricted compressor flow condition is not met, such as when the speed of the turbocharger compressor is greater than the first lower threshold speed and less than the second higher threshold speed and the compressor inlet temperature is less than the threshold temperature, the method 600 proceeds to 614 and includes maintaining the BTCC valve and SMBV positions at their current positions (e.g., opening amounts). In addition, as described above, the method may be repeated to 610 to continue adjusting the BTCC valve opening, SV timing, IV timing, and SMBV opening based on the desired blow-through and EGR flow, boost level, and the current position and timing of each of the valves listed above. Therefore, the engine may continue to operate in the baseline EGR and BTCC mode.

[0095] Alternatively, if one or more restricted compressor flow conditions are met at 612, method 600 proceeds to 616 and includes fully opening the SMBV and adjusting the BTCC valve position by a first opening amount to enable flow to the exhaust passage via the first scavenging manifold and restrict exhaust flow to the compressor via the second scavenging manifold. For example, the SMBV may be fully opened from a closed or partially closed position, and the BTCC valve may be adjusted to a first opening amount, which may include a fully open position or a partially open position. Therefore, if the BTCC valve is already fully open, the method at 616 may include maintaining the BTCC valve fully open or partially closing the BTCC valve to a first opening amount. The first opening amount is greater than 0% open, so that at 616, the BTCC valve is at least partially open. When the SMBV is fully open and the BTCC valve is fully or partially open (e.g., by a first opening amount), the total flow to the compressor inlet may be reduced. In addition, as described above with respect to Figure 2 and Figures 4 to 5 As described, due to the airway (e.g., Figure 1A The second scavenging manifold is coupled to the exhaust runner (which is coupled to the SV) at the position of the air passage 83 of the turbocharger, and the blow-through air flows through the air passage to the second scavenging manifold and to the compressor inlet via the EGR passage, while the combustion gases flow through the first scavenging manifold and to the exhaust passage via the SMBP. In this way, the method at 616 includes causing a first portion of the exhaust gas to flow through the blow-off exhaust valve and from the scavenging exhaust valve to the exhaust passage upstream of the turbocharger turbine, first causing a second portion of the exhaust gas (e.g., hotter combustion exhaust gas) to flow to the exhaust passage downstream of the turbocharger turbine and upstream of the catalyst, and then causing the blow-through air (e.g., cooler fresh air) to flow to the intake passage upstream of the turbocharger compressor. The blow-through air without EGR can help reduce the temperature at the compressor inlet, which can be particularly beneficial when a restricted compressor flow mode is entered due to the compressor inlet temperature being greater than a threshold temperature. In addition, by directing the blow-through air to the compressor inlet instead of the catalyst (e.g., Figure 1A The exhaust passage upstream of the second emission control device 72) is used to prevent catalyst degradation, which may occur when the SMBV is opened while the BTCC valve is fully closed. In addition, when the SMBV is fully opened and the BTCC valve is at least partially opened, scavenging manifold pressurization is reduced and / or avoided.

[0096] At 618, method 600 includes adjusting the first opening amount based on the condition of the compressor. For example, if the compressor inlet temperature is greater than or equal to the first threshold temperature and the compressor speed is greater than a second higher threshold speed, the first opening amount of the BTCC valve can be reduced to further limit the flow to the compressor and further reduce the compressor flow. In another example, as the compressor speed further increases to above the second higher threshold speed, the first opening amount of the BTCC valve can be further reduced. In yet another example, as the compressor inlet temperature decreases and / or the compressor speed decreases, the first opening amount of the BTCC valve can be increased from a partially open position. In this way, increased blow-by air (containing fresh air and / or unburned fuel) can be directed to the compressor inlet rather than the exhaust passage via the SMBV. In addition, the turbocharger speed can be reduced by opening the turbocharger wastegate (or increasing the opening of the turbocharger wastegate), such as by closing the turbocharger wastegate valve (e.g., Figure 1A The wastegate valve 76 of the embodiment is actuated to a further open position. After 618, the method 600 ends.

[0097] Figure 7 FIG. 1 shows a diagram of a flow control circuit in response to satisfying a restricted compressor flow condition when operating in a baseline EGR and BTCC mode and in a restricted compressor flow mode (such as described above with respect to FIG. 1 ). Figure 6 700 is a graph of adjusting the BTCC valve and SMBV position when switching between the modes described above. Specifically, graph 700 depicts the engine load at curve 702, the EGR demand at curve 704 (e.g., the desired EGR flow to the intake passage), the compressor inlet temperature at curve 706, the compressor (e.g., turbocharger) speed at curve 708, the position of the BTCC valve at curve 710, and the position of the SMBV at curve 712. For all of the above, the X axis represents time, where time increases from left to right. The Y axis of each curve represents the marked parameter, where, except for curves 710 and 712, the value increases from bottom to top, where the valve position changes from fully closed ("closed") to fully open ("open").

[0098] Prior to time t1, the compressor inlet temperature (curve 706) is below the threshold temperature T1 and the compressor speed (curve 708) is between a first lower threshold speed S1 and a second higher threshold speed S2. Figure 6As described, such conditions enable the engine to operate in baseline EGR and BTCC modes. Therefore, the BTCC valve opens (curve 710) so that EGR and blow-through can flow to the compressor inlet, and the SMBV maintains closure (curve 712) to prevent EGR and blow-through from flowing to the exhaust. Although not shown in the example of chart 700, it should be understood that the SV valve is activated. In addition, the intake valve timing and exhaust valve timing can be adjusted based on the desired EGR amount (such as the EGR demand shown in curve 704), and can be in their default timing to obtain optimal fuel economy. In addition, the engine load (curve 702) is relatively high.

[0099] At time t1, the compressor speed (curve 708) drops below the first lower threshold speed S1. For example, while the engine load remains relatively high (curve 702), there may be a reduction in engine speed, which results in low turbine power. In response to the compressor speed dropping below the first lower threshold speed S1, the engine system switches to operating in a restricted compressor flow mode and the EGR demand is reduced (e.g., the EGR flow requested at the compressor inlet is reduced). Therefore, the SMBV is fully opened (curve 712), and the BTCC valve is maintained fully open. As described above, operation with the SMBV fully open and the BTCC valve having a first opening amount (fully open in this example) reduces the flow to the compressor while preventing the scavenging manifold from becoming pressurized. In addition, fresh blow-by air preferably flows to the compressor inlet through the BTCC valve, while exhaust (e.g., the scavenging portion) preferably flows to the exhaust passage through the SMBV due to the configuration of the scavenging manifold with air ducts (refer to Figure 2 As described above). This prevents potential catalyst degradation that could occur if blow-through air instead flows through the SMBV to the exhaust passage (e.g., if the BTCC valve is closed to restrict compressor flow). At time t2, the compressor speed (plot 708) exceeds the first lower speed threshold S1, such as due to an increase in engine speed, and the engine system switches back to operating in the baseline EGR and BTCC mode. In response, the SMBV closes (plot 712).

[0100] At time t3, the compressor inlet temperature increases to be higher than threshold temperature T1. In response to this condition, the engine system switches to the restricted compressor flow operating mode again to reduce the flow of the hotter exhaust gas to the compressor. As previously mentioned, SMBV is fully opened (curve 712), and the BTCC valve is maintained in a fully open position. At time t4, the compressor temperature is reduced to below threshold temperature T1, and therefore by closing SMBV (curve 712) and increasing EGR demand (curve 704), the engine system is converted back to operate under baseline EGR and BTCC mode. However, at time t4, EGR demand (curve 704) is lower than the EGR demand at time t1 (for example, due to the reduced engine load, as shown in curve 702). For example, the EGR amount provided can be reduced by adjusting the cylinder valve timing (for example, reducing the overlap between the cylinder scavenging exhaust valve and the cylinder intake valve).

[0101] At time t5, compressor speed (curve 708) exceeds the second higher threshold speed. In addition, compressor inlet temperature (curve 706) exceeds threshold temperature T1. Therefore, the engine system switches back to operate in the restricted compressor flow mode, and opens SMBV (curve 712) so that the scavenging part of the exhaust gas flows to the exhaust passage. However, since both the compressor inlet temperature and the compressor speed are higher than their respective thresholds, the BTCC valve is adjusted from the first opening amount to the reduced opening amount, as shown in curve 710. Between time t5 and time t6, in response to the compressor inlet temperature dropping to below the first threshold temperature T1 and the compressor speed remaining higher than the second threshold speed S2, the BTCC valve returns to the first opening amount (curve 710). In this way, the position of the BTCC valve is adjusted based on the condition of the compressor to further reduce the compressor flow as needed.

[0102] At time t6, the compressor speed drops below the second threshold speed S2. Therefore, the restricted compressor flow condition is no longer met. As a result, the SMBV (curve 712) closes when the engine transitions back to the baseline EGR and BTCC mode because the restricted compressor flow condition is no longer met. Therefore, all of the EGR and blow-by air can flow to the compressor inlet via the second scavenging manifold and the first EGR passage.

[0103] By including a first scavenging manifold coupled to the scavenging exhaust valves via a plurality of exhaust runners and a second scavenging manifold coupled to the scavenging exhaust valves via a plurality of air passages, each air passage being coupled to one exhaust runner, a gradient of gas composition formed in the exhaust runners during activation of the scavenging exhaust valves can be used to preferentially flow fresh air to the compressor inlet and preferentially flow combustion gases to the exhaust passages during restricted compressor flow conditions (e.g., when the flow of EGR and blow-by air to the compressor is reduced due to low turbine power, high compressor inlet temperature, etc.). In this way, scavenging manifold pressurization can be avoided, which can cause gas (e.g., a mixture of fresh air and combustion gases) in the (one or more) scavenging manifolds to flow back into the cylinders and back to the exhaust via the blow-by exhaust valves during subsequent engine cycles. The mixture of fresh air and combustion gases may contain excess oxygen, which may degrade the ability of the downstream catalyst to reduce NOx and increase fuel consumption. Thus, a technical effect of including a second scavenging manifold with an air port is that catalyst degradation can be reduced and fuel economy can be increased during restricted compressor flow conditions, while also reducing the temperature at the compressor inlet (e.g., by at least partially opening rather than fully closing the BTCC valve during restricted compressor flow conditions, while still allowing cooler blow-through air to flow to the compressor inlet).

[0104] As an example, a method for an engine is provided, comprising: from a first group of cylinder exhaust valves, flowing a first portion of exhaust gas to an exhaust passage upstream of a turbocharger turbine; and from a second group of cylinder exhaust valves: first, flowing a second portion of exhaust gas to the exhaust passage downstream of the turbocharger turbine and upstream of a catalyst; and then, flowing blow-through air to an intake passage upstream of a turbocharger compressor. In the foregoing example, additionally or optionally, flowing the blow-through air comprises flowing a mixture of fresh air and unburned fuel to the intake passage during a positive valve overlap between an opening of each cylinder exhaust valve of the second group of cylinder exhaust valves and a corresponding intake valve. In any or all of the foregoing examples, additionally or optionally, flowing the second portion of the exhaust gas to the exhaust passage includes flowing the second portion of the exhaust gas from the second group of cylinder exhaust valves to the first scavenging manifold via a plurality of exhaust runners, each of the plurality of exhaust runners being coupled to one of the second group of cylinder exhaust valves, and then flowing the second portion of the exhaust gas from the first scavenging manifold to the exhaust passage via a bypass passage, wherein the bypass passage includes a bypass valve and is coupled to the exhaust passage downstream of the turbocharger turbine and the catalyst. In any or all of the foregoing examples, additionally or optionally, flowing the blow-through air to the intake passage includes flowing the blow-through air from the second group of cylinder exhaust valves to the second scavenging manifold via a plurality of air passages, each of the plurality of air passages being coupled to one of the plurality of exhaust runners, and then flowing the blow-through air from the second scavenging manifold to the intake passage via an exhaust gas recirculation (EGR) passage, wherein the EGR passage includes an EGR valve and is coupled to the intake passage downstream of the turbocharger compressor. In any or all of the foregoing examples, additionally or optionally, causing the second portion of the exhaust gas to flow from the second group of cylinder exhaust valves to the exhaust passage, and then causing the blow-through air to flow from the second group of cylinder exhaust valves to the intake passage includes fully opening the bypass valve while maintaining the EGR valve open at a first opening amount. In any or all of the foregoing examples, additionally or optionally, fully opening the bypass valve while maintaining the EGR valve open at a first opening amount includes fully opening the bypass valve from a previously closed or partially closed position in response to a request to reduce exhaust gas flow to an inlet of a turbocharger compressor. In any or all of the foregoing examples, additionally or optionally, a request to reduce exhaust gas flow to an inlet of a turbocharger compressor is generated in response to one or more of an inlet temperature of the turbocharger compressor reaching or exceeding a threshold inlet temperature and a speed of the turbocharger compressor reaching or exceeding a threshold speed. In any or all of the foregoing examples, the method additionally or optionally also includes adjusting the first opening amount based on a condition of the turbocharger compressor, including reducing the first opening amount when one or more of the following: an inlet temperature of the turbocharger compressor further increases above a threshold temperature and a speed of the turbocharger compressor further increases above a threshold speed.

[0105] As another example, a system for an engine is provided, comprising: a first set of exhaust valves, the first set of exhaust valves being fluidly coupled to an exhaust passage upstream of a turbocharger turbine; and a second set of exhaust valves, the second set of exhaust valves being fluidly coupled to each of the following: coupled to a first scavenging manifold via a plurality of exhaust runners, each exhaust runner being coupled to a valve of a second set of exhaust valves, the first scavenging manifold being coupled to an exhaust passage downstream of a turbocharger turbine; and coupled to a second scavenging manifold via a plurality of air passages, each air passage being coupled to an exhaust runner of the plurality of exhaust runners, the second scavenging manifold being coupled to an intake passage upstream of a turbocharger compressor. In the foregoing examples, additionally or optionally, the first scavenging manifold is coupled to the exhaust passage downstream of the turbocharger turbine and the first catalyst. In any or all of the foregoing examples, additionally or optionally, the first scavenging manifold is coupled to the exhaust passage via a bypass passage, the bypass passage comprising a bypass valve adapted to restrict flow to the exhaust passage. In any one or all of the foregoing examples, additionally or optionally, the bypass passage is coupled to the exhaust passage between the first catalyst and the second catalyst, the second catalyst being located downstream of the turbocharger turbine. In any one or all of the foregoing examples, additionally or optionally, the second scavenging manifold is coupled to the intake passage upstream of the turbocharger compressor via an exhaust gas recirculation passage coupled between the second scavenging manifold and the intake passage, the exhaust gas recirculation passage comprising a valve adapted to restrict flow to the inlet of the turbocharger compressor. In any one or all of the foregoing examples, additionally or optionally, each of the plurality of air passages has a first end portion directly coupled to one exhaust runner near a corresponding valve of the second set of exhaust valves, and a second end portion directly coupled to the second scavenging manifold. In any one or all of the foregoing examples, additionally or optionally, the second end portion of each air passage is spaced apart from the second end portion of the adjacent air passage along the length of the second scavenging manifold, and wherein the valve in the exhaust gas recirculation passage is located downstream of the position where the plurality of air passages are coupled to the second scavenging manifold. In any or all of the foregoing examples, additionally or optionally, the first end of each air passage is positioned closer to a corresponding valve of the second set of exhaust valves than a location at which the one exhaust runner is coupled to the first scavenging manifold. In any or all of the foregoing examples, additionally or optionally, a diameter of each of the plurality of air passages is smaller than a diameter of each of the plurality of exhaust runners.

[0106] As another example, a system for an engine is provided, comprising: a plurality of cylinders, each cylinder including a first exhaust valve and a second exhaust valve; a blow-off exhaust manifold coupled to the first exhaust valve of each cylinder, the blow-off exhaust manifold coupled to an exhaust passage upstream of a turbocharger turbine; a first scavenging exhaust manifold coupled to the second exhaust valve of each cylinder via an exhaust runner, the first scavenging exhaust manifold coupled to the exhaust passage downstream of the turbocharger turbine and upstream of a catalyst; a second scavenging exhaust manifold coupled to the second exhaust valve of each cylinder via an air passage coupled to the exhaust runner, the second scavenging exhaust manifold coupled to an intake passage upstream of a turbocharger compressor; and a controller having computer-readable instructions stored on a memory for operating the first exhaust valve of each cylinder at a timing different from that of the second exhaust valve of each cylinder. In the foregoing examples, the system also additionally or optionally includes a bypass passage coupling the first scavenged exhaust manifold to the exhaust passage downstream of the turbocharger turbine and upstream of the catalyst; and an exhaust gas recirculation (EGR) passage coupling the second scavenged exhaust manifold to the intake passage upstream of the turbocharger compressor, wherein the computer readable instructions also include instructions for opening a bypass valve disposed in the bypass passage and maintaining an EGR valve disposed in the EGR passage open in response to the turbocharger compressor reaching an operating threshold. In any or all of the foregoing examples, additionally or optionally, the operating threshold includes one or more of an inlet temperature of the turbocharger compressor reaching or exceeding a threshold inlet temperature and a speed of the turbocharger compressor reaching or exceeding a threshold speed.

[0107] In another representation, a method for an engine includes: during a first condition, flowing both exhaust and blow-through air from a cylinder scavenging exhaust valve to an inlet of a compressor of a turbocharger via a second scavenging manifold coupled to the cylinder scavenging exhaust valve via a plurality of air passages; and during a second condition, flowing blow-through air to an inlet of a compressor of a turbocharger via the second scavenging manifold, and flowing exhaust gas to an exhaust passage downstream of a turbine and upstream of a catalyst of the turbocharger via a first scavenging manifold, the first scavenging manifold fluidly coupled to each of the cylinder scavenging exhaust valves via a plurality of exhaust runners, and the second scavenging manifold fluidly coupled to each of the cylinder scavenging exhaust valves via a plurality of exhaust runners and a plurality of air passages. In the foregoing example, additionally or optionally, the engine is operated in the first condition in response to a request for exhaust gas recirculation (EGR), and the engine is operated in the second condition in response to a restricted compressor flow condition. In any or all of the foregoing examples, additionally or optionally, the restricted compressor flow condition includes at least one of turbine power less than a threshold power, turbine speed less than a first threshold speed, compressor speed greater than a second threshold speed, compressor speed greater than a first threshold speed, and a temperature at an inlet of the compressor greater than a threshold temperature. In any or all of the foregoing examples, the method also additionally or optionally includes: during a first condition, opening an EGR valve disposed in an EGR passage (which couples the second scavenging manifold to the inlet of the compressor) to a first opening amount and maintaining a scavenging manifold bypass valve (SMBV) disposed in a scavenging manifold bypass passage (which couples the first scavenging manifold to the exhaust passage) in a closed position; and in a second condition, maintaining the EGR valve at the first opening amount and fully opening the SMBV. In any or all of the foregoing examples, the method may include operating a cylinder scavenging exhaust valve at a different timing than a cylinder blow-off exhaust valve, wherein each cylinder includes a cylinder scavenging exhaust valve coupled to each of a first scavenging manifold and a second scavenging manifold, and a cylinder blow-off exhaust valve coupled to the blow-off manifold, the blow-off manifold being adapted to flow exhaust gas to a turbine.

[0108] In yet another representation, the vehicle system described above is included in a hybrid vehicle system, which also includes an electric machine; a transmission; one or more wheels coupled to the transmission; a first clutch coupled between the engine and the transmission; and a second clutch coupled between the electric machine and the transmission. In the foregoing examples, additionally or optionally, engaging the first clutch couples the engine to the one or more wheels via the transmission. In any or all of the foregoing examples, additionally or optionally, engaging the second clutch couples the electric machine to the one or more wheels via the transmission.

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

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

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

Claims

1. A method for an engine, comprising: flowing a first portion of the exhaust gas from the first set of cylinder exhaust valves to an exhaust passage upstream of a turbocharger turbine; as well as From the second bank of cylinder exhaust valves: First, flowing a second portion of the exhaust gas to the exhaust passage downstream of the turbocharger turbine and upstream of the catalyst, wherein the second group of cylinder exhaust valves is coupled to a first scavenging manifold via a plurality of exhaust runners, the first scavenging manifold being coupled to the exhaust passage downstream of the turbocharger turbine; as well as Then, the blow-by air is made to flow to the intake passage upstream of the turbocharger compressor via the second scavenging manifold. The second group of cylinder exhaust valves are coupled to the second scavenging manifold via a plurality of air passages, wherein a first end of each of the plurality of air passages is directly coupled to a corresponding exhaust runner among the plurality of exhaust runners, the first end being close to the second group of cylinder exhaust valves, and a second end of each of the plurality of air passages is directly coupled to the second scavenging manifold, and the second scavenging manifold is coupled to the intake passage upstream of the turbocharger compressor. 2 . The method of claim 1 , wherein flowing blow-through air comprises flowing a mixture of fresh air and unburned fuel to the intake passage during a positive valve overlap between opening of each cylinder exhaust valve of the second group of cylinder exhaust valves and a corresponding intake valve.

3. The method of claim 1 , wherein flowing the second portion of the exhaust gas to the exhaust passage comprises flowing the second portion of the exhaust gas from the second group of cylinder exhaust valves to a first scavenging manifold via the plurality of exhaust runners, each exhaust runner of the plurality of exhaust runners being coupled to one of the second group of cylinder exhaust valves, and then flowing the second portion of the exhaust gas from the first scavenging manifold to the exhaust passage via a bypass passage comprising a bypass valve and being coupled to the exhaust passage downstream of the turbocharger turbine and the catalyst.

4. The method of claim 3 , wherein flowing the blow-through air to the intake passage comprises flowing the blow-through air from the second group of cylinder exhaust valves to a second scavenging manifold via the plurality of air passages, each of the plurality of air passages being coupled to one of the plurality of exhaust runners, and then flowing the blow-through air from the second scavenging manifold to the intake passage via an exhaust gas recirculation passage (EGR passage) that includes an EGR valve and is coupled to the intake passage upstream of the turbocharger compressor.

5. The method of claim 4, wherein causing the second portion of the exhaust gas to flow from the second group of cylinder exhaust valves to the exhaust passage and then causing blow-through air to flow from the second group of cylinder exhaust valves to the intake passage comprises fully opening the bypass valve while maintaining the EGR valve open at a first opening amount.

6. The method of claim 5, wherein fully opening the bypass valve while maintaining the EGR valve open at the first amount of opening comprises fully opening the bypass valve from a previously closed or partially closed position in response to a request for reduced exhaust gas flow to an inlet of the turbocharger compressor.

7. The method of claim 6, wherein the request for reduced exhaust gas flow to the inlet of the turbocharger compressor is generated in response to one or more of an inlet temperature of the turbocharger compressor reaching or exceeding a threshold inlet temperature and a speed of the turbocharger compressor reaching or exceeding a threshold speed.

8. The method of claim 5, further comprising adjusting the first opening amount based on a condition of the turbocharger compressor, including decreasing the first opening amount when one or more of the following: an inlet temperature of the turbocharger compressor further increases above a threshold temperature and a speed of the turbocharger compressor further increases above a threshold speed.

9. A system for an engine, comprising: a plurality of cylinders, each of the plurality of cylinders including a first exhaust valve fluidly coupled to an exhaust passage upstream of a turbocharger turbine, and a second exhaust valve fluidly coupled to each of: coupled to a first scavenging manifold via an exhaust runner, the first scavenging manifold being coupled to the exhaust passage downstream of the turbocharger turbine; as well as The exhaust manifold is coupled to a second scavenging manifold via an air passage, wherein a first end of the air passage is directly coupled to the exhaust runner, the first end is proximate to the second exhaust valve, and a second end of the air passage is directly coupled to the second scavenging manifold, and the second scavenging manifold is coupled to an intake passage upstream of a turbocharger compressor. 10 . The system of claim 9 , wherein the first scavenging manifold is coupled to the exhaust passage downstream of the turbocharger turbine and a first catalyst.

11. The system of claim 10, wherein the first scavenging manifold is coupled to the exhaust passage via a bypass passage, the bypass passage including a bypass valve adapted to restrict flow to the exhaust passage, and wherein the bypass passage is coupled to the exhaust passage between the first catalyst and a second catalyst, the second catalyst being located downstream of the turbocharger turbine.

12. The system of claim 9, wherein the second scavenging manifold is coupled to the intake passage upstream of the turbocharger compressor via an exhaust gas recirculation passage coupled between the second scavenging manifold and the intake passage, the exhaust gas recirculation passage including a valve adapted to restrict flow to an inlet of the turbocharger compressor. 13 . The system of claim 9 , wherein the second end of the air passage of each cylinder of the plurality of cylinders is spaced apart from the second end of an adjacent air passage along a length of the second scavenging manifold.

14. The system of claim 9, wherein a diameter of the air passage is smaller than a diameter of the exhaust flow passage.

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