Double-acting valve enabled catalyst bypass

Abstract

An internal combustion engine includes a cylinder head with an exhaust manifold configured to supply exhaust gas to a main exhaust aftertreatment system through a main exhaust outlet, the main exhaust aftertreatment system having a main catalytic converter; a bypass passage in fluid communication with the exhaust manifold through a bypass port; the bypass catalytic converter is arranged in the bypass channel; and a double-acting valve assembly configured to move between a first position sealing the bypass port and a second position sealing the main exhaust outlet. Under cold start, long idle, and / or low main catalytic converter temperature conditions, the dual-acting valve assembly moves to a second position to direct exhaust gas flow through the bypass passage and the bypass catalytic converter to reduce emissions.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 343,839, filed May 19, 2022, and U.S. Non-Provisional Patent Application No. 18 / 309,382, filed April 28, 2023. The disclosures of each application are incorporated herein by reference in their entirety. Technical Field

[0003] The present application relates generally to internal combustion engine exhaust treatment systems and, more particularly, to internal combustion engines having light-off catalyst bypass systems. Background Art

[0004] In conventional internal combustion aftertreatment systems, it is difficult to achieve low tailpipe emissions in the time immediately following a cold engine start due to the low catalyst conversion efficiency of the cold catalyst. In order to achieve acceptable conversion efficiency, the catalyst must exceed a predetermined light-off temperature. In certain systems, faster light-off temperatures can be achieved, but usually at the expense of high exhaust system back pressure, durability, life, cost and / or complexity. Therefore, while such conventional systems do serve their intended purpose, it is desirable to provide continued improvements in the related art. Summary of the invention

[0005] According to an exemplary aspect of the present invention, an internal combustion engine is provided. In an exemplary embodiment, the engine includes: a cylinder head with an exhaust manifold configured to supply exhaust gas to a main exhaust aftertreatment system having a main catalytic converter through a main exhaust outlet; a bypass channel, the bypass channel is fluidly connected to the exhaust manifold via a bypass port; a bypass catalytic converter, the bypass catalytic converter is arranged in the bypass channel; and a double-acting valve assembly, the double-acting valve assembly is configured to move between a first position sealing the bypass port and a second position sealing the main exhaust outlet. Under cold start, long idle and / or low main catalytic converter temperature conditions, the double-acting valve assembly moves to the second position to guide the exhaust flow through the bypass channel and the bypass catalytic converter to reduce emissions.

[0006] In addition to the above, the described engine may also include one or more of the following features: a main outlet conduit configured to receive an exhaust flow from an exhaust manifold and define a main exhaust outlet; wherein a bypass port is formed in the main outlet conduit; wherein the main outlet conduit is a separate and distinct component configured to be coupled to a cylinder head; wherein the main outlet conduit is a turbine inlet; and wherein the main outlet conduit includes a recessed first valve seat formed around the bypass port, and wherein in a first position, the double-acting valve assembly is configured to sit flush within the recessed first valve seat to facilitate preventing obstruction of exhaust flow within the main outlet conduit.

[0007] In addition to the above, the described engine may include one or more of the following features: wherein the main outlet conduit also includes a recessed second valve seat formed around the main exhaust outlet, and wherein in this second position, the double-acting valve assembly is configured to be flushly located within the recessed second valve seat to facilitate preventing obstruction of exhaust gas flow within the main outlet conduit; wherein the double-acting valve assembly includes a valve coupled to a valve shaft; wherein the valve shaft is rotatably located within a hole formed in the main outlet conduit, and the valve shaft is rotatable to move the valve to a first position to seal the bypass port, and to a second position to seal the main exhaust outlet; an actuator assembly, which is operably coupled to the valve shaft to rotate the valve shaft within the hole; and a turbocharger, wherein the actuator assembly is coupled to the turbocharger, and wherein the actuator connecting rod is operably coupled between the actuator assembly and the valve shaft for selective rotation thereof.

[0008] In addition to the above, the engine may include one or more of the following features: wherein the bypass passage is an external conduit including a first conduit, a bypass catalyst conduit, and a second conduit, wherein the first conduit is fluidly coupled to the bypass port and configured to supply exhaust gas to the bypass catalyst conduit including the bypass catalytic converter, and wherein the second conduit is fluidly coupled between the bypass catalyst conduit and a bypass flow inlet of the main exhaust aftertreatment system.

[0009] In addition to the above, the described engine may also include one or more of the following features: wherein a bypass flow inlet is formed in a main exhaust duct of a main exhaust aftertreatment system, and wherein the bypass flow inlet is located upstream of a main catalytic converter; wherein the bypass flow inlet is located downstream of a turbocharger outlet; wherein the bypass flow inlet is oriented to direct the exhaust flow onto an upstream face of the main catalytic converter to accelerate heating thereof; wherein a bypass port is formed in a collector portion of an exhaust manifold; wherein a bypass passage is integrally formed in a cylinder head; and a water jacket formed in the cylinder head proximate a bypass catalyst duct housing a bypass catalytic converter, wherein the water jacket is configured to circulate a coolant to provide cooling to the bypass catalytic converter.

[0010] Further areas of applicability of the teachings of the present disclosure will become apparent from the detailed description, claims, and drawings provided below, wherein the same reference numerals refer to the same features in the several views of the drawings. It should be understood that the detailed description (including the embodiments and reference numerals disclosed therein) is merely exemplary in nature and is used only for illustrative purposes and is not intended to limit the scope of the present disclosure, its application, or use. Therefore, changes that do not depart from the gist of the present disclosure are intended to be within the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a cross-sectional view of an example internal combustion engine having a light-off catalyst bypass system according to the principles of the present application;

[0012] Figure 2 According to the principle of this application Figure 1 A side view of an example light-off catalyst bypass system shown coupled between a turbocharger and a primary exhaust aftertreatment system;

[0013] Figure 3 According to the principle of this application Figure 2 , which illustrates an example double-acting valve assembly of a light-off catalyst bypass system;

[0014] Figure 4 It is arranged in the main outlet pipe according to the principle of this application. Figure 2 A perspective view of an example double-acting valve assembly;

[0015] Figure 5 It is in the first position according to the principle of this application Figure 4 A perspective view of an example double-acting valve assembly;

[0016] Figure 6 According to the principle of the present application, the second position Figure 5 A perspective view of an example double-acting valve assembly; and

[0017] Figure 7 is a cross-sectional view of an example cylinder head and exhaust manifold with an integrated light-off catalyst bypass system according to the principles of the present application. DETAILED DESCRIPTION

[0018] Some conventional aftertreatment systems have limited or no ability to bring the catalyst to light-off temperature to efficiently convert harmful exhaust components before about fifteen seconds after a cold start in a turbocharged system. Every second that the engine is running, the catalyst does not reach or exceed the light-off temperature, and CO, HC and NOx cannot be efficiently converted. The short time before the catalyst lights off is responsible for a large portion of CO, HC and NOx breakthrough during on-off cycle starts and long idles. In conventional systems, one or more catalysts are traditionally located a distance downstream of the heat exhaust port and / or turbocharger outlet, and are typically in the main exhaust stream throughout the service life of the vehicle.

[0019] Therefore, this paper describes a system and method for a catalyst bypass system for improving exhaust emissions during operation of an internal combustion engine. The system utilizes a specially designed dual-acting valve and bypass system and an additional integrated catalyst. During system operation, the dual-acting valve is actuated to achieve targeted flow restriction through the exhaust manifold / turbine, thereby routing the exhaust gas to one or more bypass catalysts instead of through the exhaust manifold / turbine and then re-entering the main exhaust path. This will allow rapid catalyst ignition and improve the conversion of harmful exhaust components without the need for multiple valves / actuation systems to limit the flow through the exhaust manifold / turbine while also allowing the flow through the bypass catalyst.

[0020] In some examples, system features include: a system including a dual-acting valve that redirects engine exhaust using a single actuator with a high restrictive valve position; a system that allows exhaust to bypass the main exhaust flow path / turbine, through one or more additional catalysts for starting, long idle, and low main catalyst temperature conditions; and a valve system that is configured to seal high pressure exhaust gas (P3) from the exhaust manifold via a machined valve seat that accommodates the dual-acting valve interface.

[0021] Additional example system features include: a valve system spindle having various forms of seals both axially and radially for sealing the system from the external environment; the valve system is machined with direct line-of-sight access through the inlet; a one-piece double-acting valve can be assembled through the inlet; and the system allows for improved exhaust system efficiency and reduced degradation due to aging.

[0022] In an example embodiment, the system utilizes a double-acting valve operated via a single actuator and a bypass system including an auxiliary bypass catalyst. The double-acting valve is configured to be used in conjunction with a bypass catalyst system, which typically includes a flow passage, a catalyst, and a double-acting valve for blocking exhaust flow. The inlet of the bypass catalyst system is located before the turbine inlet or at the exhaust manifold collector. In some examples, the inlet is as close to the exhaust port or cylinder head as possible to minimize heat loss from the exhaust gas. Therefore, the close proximity of the auxiliary catalyst to the exhaust gas in the cylinder head enables rapid heating, thereby accelerating the conversion rate of harmful exhaust components.

[0023] Due to the small size and small surface area / distance between the bypass catalyst and the exhaust valve, the bypass catalyst warms up much faster than the conventional catalyst. During a cold engine start event or other situation where exhaust gas needs to flow through the catalyst bypass system, the dual-acting valve is actuated to restrict flow to the turbine and route the exhaust gas through the catalyst bypass system. Restricting flow directly to the turbine and conventional catalyst during cold starts is desirable because the conventional catalyst cannot effectively convert exhaust gas components until a minimum temperature or catalyst "light-off" temperature is reached. Gases leaving the bypass catalyst are directed to the inlet of the main conventional catalyst to help the main catalyst achieve faster light-off.

[0024] In an example embodiment, the system has two main positions, a bypass position and a default position. The bypass position is enabled when the valve restricts the main exhaust flow through the turbine and the exhaust gases are routed through a bypass catalyst system. The default position is enabled when the valve allows the main exhaust flow to pass through the turbine in a smooth flow path without interference from the dual-acting valve mechanical structure. In this way, the dual-acting valve is actuated to the bypass position or default position and sits flush on the machined valve seat geometry, which is machined using a direct line of sight access for machining and assembly. Once main catalyst ignition is achieved, the valve can begin to actuate to the default position.

[0025] Advantages of this system include: extremely fast catalyst light-off time; dual-acting valve with the ability to: seal the exhaust manifold / turbo or bypass route with a single valve and actuator (no need for multiple valves); drive most or all of the exhaust flow through the bypass catalyst before passing through the main exhaust path by using a single dual-acting valve with a single actuator; extremely short distance, surface area and thermal mass between the exhaust port and the bypass catalyst by bypassing the turbocharger turbine; deactivation of the bypass catalyst after light-off; extremely high cell density matrix in the catalyst, which would not be used in a non-bypassable system due to excessive back pressure; and moving PGM (platinum group metals) away from the main catalyst and onto the bypass catalyst to better utilize the PGM.

[0026] Known fast catalyst light-off solutions do not utilize a single dual-acting valve integrated with a single actuator in series with the bypass catalyst system to achieve improved cold start emissions. The flow restriction of the dual-acting valve directs the exhaust through the bypass catalyst system instead of the turbine, significantly reducing the wetted surface area and thermal mass to remove heat before the main catalyst. This, combined with the low thermal mass of the bypass catalyst itself, results in very rapid catalyst warm up and very fast light-off times. This warm-up behavior can facilitate the use of less extreme calibration strategies to generate more heat in the exhaust, which can improve NVH and reduce fuel consumption during cold starts.

[0027] After rapid light-off, the catalyst begins to effectively convert exhaust gas constituents through exothermic reactions and generates more exhaust heat, which helps heat the main catalyst. Once the main catalyst reaches light-off temperature, the dual-acting valve can be closed to block the bypass catalyst and regular exhaust flow can continue. Selective deactivation of the bypass catalyst system provides benefits to both the bypass catalyst and the main catalyst.

[0028] In one example, a bypass catalyst can have a high precious metal loading with a high cell density matrix so that it has a very high conversion efficiency at cold start. This high cell density matrix can cause significant exhaust back pressure in conventional systems and accelerate aging due to continued exposure to high exhaust temperatures and exhaust flow. In the current system, back pressure and aging are not a problem because the auxiliary bypass catalyst can be bypassed outside cold start conditions. Similarly, the main catalyst can use less precious metals because it does not rely on cold start emissions. The precious metal loading of the main (and larger) catalyst can constitute a significant cost to the emission system and is also a reason for aging or performance degradation of the emission system over its entire service life.

[0029] First reference Figure 1 and Figure 2 , an internal combustion engine 10 is shown having a cylinder head 12. In an exemplary embodiment, the cylinder head 12 is configured to selectively supply exhaust gas to a main exhaust aftertreatment system 14 and a light-off catalyst bypass system 16. As described in more detail herein, the light-off catalyst bypass system 16 is selectively utilized during cold start, long idle, and / or cold catalyst conditions to quickly heat to a light-off temperature, thereby quickly achieving low tailpipe emissions.

[0030] like Figure 1As shown, the cylinder head 12 includes an integrated exhaust manifold 20 having a plurality of cylinder exhaust passages 22 that merge together to form a collector portion or main exhaust passage 24 having an outlet 26. In alternative embodiments, the exhaust manifold 20 may be coupled (e.g., bolted) to the cylinder head. A main outlet conduit 30 receives exhaust gas from the manifold outlet 26 and is configured to direct the exhaust gas to the main exhaust aftertreatment system 14. In the example shown, the main outlet conduit 30 is a separate and distinct component coupled to the cylinder head 12 and is configured to provide exhaust gas to an inlet passage 32 of a turbocharger turbine 34. In some examples, the main outlet conduit 30 and the turbine inlet passage 32 are integral. The exhaust gas expanded in the turbine 34 is then directed to the main exhaust aftertreatment system 14. However, it should be understood that the engine 10 may include a supercharger instead of a turbocharger, or the engine 10 may not include a turbocharger, so that the main outlet conduit 30 is directly connected to the main exhaust aftertreatment system 14.

[0031] In an exemplary embodiment, the main exhaust aftertreatment system 14 generally includes a main exhaust conduit 40 having one or more main catalytic converters 42 for reducing or converting desired exhaust gas components, such as carbon monoxide (CO), hydrocarbons (HC) and / or nitrogen oxides (NOx). The main exhaust conduit 40 is fluidly coupled to the exhaust manifold main outlet 26 (optionally coupled via the turbocharger turbine 34) and is configured to receive exhaust gas from the vehicle engine 10 and supply the exhaust gas to the main catalytic converter 42. In order to efficiently reduce or convert CO, HC and NOx, the main catalytic converter 42 must reach a predetermined light-off temperature. However, during certain vehicle operations, such as cold start, long idle and cold catalyst conditions, the main catalytic converter 42 is below the light-off temperature, and therefore the catalyst conversion efficiency is low.

[0032] In order to efficiently reduce or convert unwanted exhaust components when the main catalytic converter 42 is below the light-off temperature, the vehicle utilizes the light-off catalyst bypass system 16 to redirect at least a portion of the exhaust gas from the exhaust manifold 20 into the bypass passage 50 and through the auxiliary bypass catalytic converter 52. Since the bypass catalyst 52 is located near the cylinder head 12, it is close to the engine combustion chamber and receives the exhaust gas faster and at a higher temperature than the main catalytic converter 42. Therefore, the bypass catalyst 52 is quickly heated to its predetermined light-off temperature to achieve high catalyst conversion efficiency before the main catalytic converter 42 alone.

[0033] Continue to refer Figure 1 and Figure 2 In the exemplary embodiment, the light-off catalyst bypass system 16 generally includes a bypass passage 50, a bypass catalyst 52, and a dual-acting valve assembly 54. Figure 2As shown, the bypass passage 50 includes a first conduit 56, a bypass catalyst conduit 58, and a second conduit 60. The first conduit 56 includes a first end 62 and a second end 64. In the example shown, the first end 62 is configured to be coupled to the main outlet conduit 30 at a bypass port 66 formed in the main outlet conduit 30, the bypass port 66 being proximate to the dual-acting valve assembly 54. In the example embodiment, the first conduit first end 62 is configured to selectively receive the exhaust flow and then direct the exhaust flow to the first conduit second end 64, which is fluidly coupled to the bypass catalyst conduit 58. The bypass catalyst conduit 58 is configured to receive the bypass catalyst 52 and then direct the exhaust flow to the bypass passage second conduit 60.

[0034] like Figure 2 As shown, the second conduit 60 includes a first end 68 and a second end 70. The first end 68 is fluidly coupled to the bypass catalyst conduit 58 to receive the exhaust flow therefrom. The second conduit 60 guides the exhaust flow to the second end 70, and the second end 70 is fluidly coupled to the main exhaust conduit 40 at the bypass flow inlet 72. The bypass flow inlet 72 is located downstream of the turbocharger outlet 74 and upstream of the main catalytic converter 42. In the exemplary embodiment, the bypass flow inlet 72 is oriented so that the bypass exhaust flow is directed to the upstream face of the main catalytic converter 42 to accelerate its preheating. In other arrangements, the bypass flow inlet 72 can be located in the turbocharger inlet and / or outlet.

[0035] As discussed, the bypass catalyst 52 is disposed within the bypass passage 50, which is fluidly connected between the main outlet conduit 30 and the main exhaust conduit 40. The main outlet conduit 30 defines an inlet 80, a main exhaust outlet 82, and a bypass port 66. The inlet 80 receives exhaust gas from the exhaust manifold outlet 26, the main exhaust outlet 82 directs the exhaust gas to the main exhaust conduit 40, and the bypass port 66 directs the exhaust gas to the bypass passage 50.

[0036] Additional references Figures 3 to 6 , the double-acting valve assembly 54 will be described in more detail. In the exemplary embodiment, the double-acting valve assembly 54 includes a valve seal or valve 90 coupled to a valve spindle or valve shaft 92, which is rotatably located in a bore 94 formed in the body of the main outlet conduit 30 (shown as a portion of the turbine inlet passage in this example). The valve shaft 92 is operably coupled to an actuator linkage 96 ( Figures 2 to 3 ), the actuator link 96 is in turn operably coupled to the actuator assembly 98 ( Figure 2 In the illustrated example, the actuator assembly 98 is coupled to the turbocharger housing 36 (eg, Figure 2), but it should be understood that the assembly 98 can be coupled to any suitable component of the engine 10. The actuator assembly 98 includes an actuator (eg, a motor, not shown) configured to selectively drive the actuator linkage 96 to rotate the valve shaft 92.

[0037] Rotation of the valve shaft 92 is configured to move the valve 90 to a first position 100 ( Figure 5 ) (default position) and a second position 102 ( Figure 6 )(bypass position). In this way, a single valve 64 is located within the main outlet conduit 30 and is configured to move to any desired position between the first position 100 and the second position 102.

[0038] Advantageously, in the exemplary embodiment, the main outlet conduit 30 is formed with a first valve seat 110 ( Figure 6 ) and the second valve seat 112 ( Figure 5 ). The first valve seat 110 and the second valve seat 112 are recessed within the main outlet conduit 30 and are similar in size and shape to the valve 90. In this manner, in the first position 100, the valve 90 is flushly seated within the recessed first valve seat 110 and fully seals the bypass port 66. Thus, features of the valve 90 are positioned outside the exhaust flow to facilitate preventing obstruction of exhaust flow within the main outlet conduit 30. Similarly, in the second position 102, the valve 90 is flushly seated within the recessed second valve seat 112 and fully seals the main exhaust outlet 82. Thus, features of the valve 90 are positioned outside the exhaust flow through the bypass port 66 to facilitate preventing obstruction of exhaust flow within the main outlet conduit 30.

[0039] A controller 114 (e.g., an engine control unit) is in signal communication with the valve assembly 54 (e.g., via the actuator assembly 98), and is configured to move the valve assembly 54 to any position between the first position 100 and the second position 102. As used herein, the term controller refers to an application specific integrated circuit (ASIC), electronic circuitry, processor (shared, dedicated, or group) and memory executing one or more software or firmware programs, combinational logic circuitry, and / or other suitable components that provide the described functionality.

[0040] In one example, the bypass catalyst 52 is a three-way catalyst configured to remove CO, HC, and NOx from the exhaust passing therethrough, as described in greater detail herein. However, it should be understood that the bypass catalyst 52 can be any suitable catalyst that enables the light-off catalyst bypass system 16 to remove any desired pollutants or compounds, such as, for example, a hydrocarbon trap or a four-way catalyst. In another example, the bypass catalyst 52 has a cell density between about 800 and about 1,200 cells per square inch, or a cell density between 800 and 1,200 cells per square inch.

[0041] In an exemplary embodiment, the light-off catalyst bypass system 16 is configured to selectively operate in (i) a normal or warm catalyst mode, (ii) a cold catalyst mode, and (iii) a mixed flow mode. In the warm catalyst mode, the controller 114 determines that the main catalyst 42 has reached a predetermined light-off temperature (e.g., via a temperature sensor, modeling, etc.) and moves the valve 90 to the first position 100 ( Figure 5 ) to seal the bypass port 66. In this mode, the valve assembly 54 facilitates preventing exhaust gas in the exhaust manifold 20 from entering the bypass passage 50 and, therefore, the bypass catalyst 52. Instead, the exhaust gas is directed through the main exhaust passage 24 (and the turbine 34, if present), into the main exhaust conduit 40, and through the main catalytic converter 42 before being exhausted to the atmosphere.

[0042] In the cold catalyst mode, the controller 114 determines that the main catalytic converter 42 is below a predetermined light-off temperature or another vehicle condition exists, such as, for example, a cold start or long idle condition. The controller 114 moves the valve 90 to the second position 102 ( Figure 6 ), sealing the main exhaust outlet 82. In this mode, the valve assembly 54 facilitates preventing exhaust gas in the exhaust manifold 20 from directly entering the main exhaust conduit 40. Instead, the exhaust gas is directed through the bypass passage 50 and the bypass catalyst 52 before being directed to the main exhaust conduit 40 and the atmosphere. Once the main catalytic converter 42 has reached the light-off temperature, the controller 114 can switch the light-off catalyst bypass system 16 to the normal mode.

[0043] In the mixed flow mode, the controller 114 moves the valve 90 to a partially open / closed state between the first position 100 and the second position 102. In this mode, a first portion of the exhaust gas from the exhaust manifold 20 is directed through the main exhaust outlet 82 and into the main exhaust conduit 40. At the same time, a second portion of the exhaust gas from the exhaust manifold 20 is directed through the bypass passage 50 and the bypass catalyst 52. The two portions of exhaust gas are recombined in the main exhaust conduit 40 and then passed through the main catalytic converter 42 and discharged into the atmosphere. It should be understood that the controller 114 can adjust the position of the valve 90 in real time to control various conditions of the vehicle and its exhaust aftertreatment system 14.

[0044] Reference now Figure 7 , an alternative arrangement of a light-off catalyst bypass system is shown at reference numeral 116. The light-off catalyst bypass system 116 is similar to the light-off catalyst bypass system 16, except that the bypass passage and valve assembly are integrated into the cylinder head 12 and / or the exhaust manifold 20. The same reference numerals indicate the same components. In an exemplary embodiment, the light-off catalyst bypass system 116 includes a bypass passage 150 and a valve assembly 154 that are integrated into the exhaust manifold 20. The bypass passage 150 is formed in the body of the exhaust manifold 20, for example, by casting and / or machining. A bypass catalyst 152 is disposed within the bypass passage 150. A bypass port 166 is formed in the exhaust manifold main exhaust passage 24, proximate to the valve assembly 154, which is located at the exhaust manifold outlet 26.

[0045] When the valve 90 is in a first (default) position (not shown), the valve 90 is flushly seated in a valve seat 170 formed in the exhaust manifold 20 to seal the bypass port 166. When the valve 90 is in a second (bypass) position (shown in phantom), the valve 90 is flushly seated in a valve seat 172 formed in the exhaust manifold 20 to seal the exhaust manifold outlet 26. In this second position, exhaust gas in the exhaust manifold 20 is directed through the bypass port 166, through the bypass catalyst 152 and to the outlet port 168. The outlet port 168 is fluidly coupled to the bypass flow inlet 72 via, for example, an external conduit (not shown). The light-off catalyst bypass system 116 otherwise operates in a manner similar to the light-off catalyst bypass system 16.

[0046] In an exemplary embodiment, the cylinder head 12 and the exhaust manifold 20 also include a water jacket 180. Advantageously, the water jacket 180 includes a flow channel 182 extending to and disposed around the bypass passage 150 and the bypass catalyst 152. In this manner, the cylinder head coolant circuit extends around the bypass catalyst 152 and is configured to supply coolant (e.g., water) around the bypass catalyst 152. By keeping the bypass catalyst 152 at a lower temperature, particularly when exhaust gas is not passing through (e.g., during normal operation), the life and durability of the catalyst 152 is extended.

[0047] Systems and methods for improving vehicle emission system efficiency, particularly during cold start, long idle, and low main catalyst temperature conditions, are described herein. The system includes a light-off catalyst bypass having a dual-acting valve that selectively blocks flow to a small bypass catalyst located in the bypass. When the valve is in the light-off position, exhaust gas from the exhaust port is directed through the small bypass catalyst and ultimately back to the main exhaust system. When the valve is in a normal operating condition, exhaust flow is directed through the manifold and optional turbocharger, directly to the main exhaust system.

[0048] It should be understood that the mixing and matching of features, elements, methods, systems and / or functions between various examples may be expressly contemplated herein, so that those skilled in the art will recognize from the present teachings that features, elements, systems and / or functions of one example may be appropriately incorporated into another example, unless otherwise specified above. It should also be understood that the description, including the disclosed examples and drawings, is merely exemplary in nature and is used for illustrative purposes only, and is not intended to limit the scope of the present disclosure, its application or use. Therefore, changes that do not depart from the subject matter of the present disclosure are intended to fall within the scope of the present disclosure.

Claims

1. An internal combustion engine, comprising: a cylinder head having an exhaust manifold configured to supply exhaust gas via a main exhaust outlet to a main exhaust aftertreatment system having a main catalytic converter; a bypass passage fluidly communicating with the exhaust manifold via a bypass port; a bypass catalytic converter, the bypass catalytic converter being disposed in the bypass channel; as well as a double-acting valve assembly configured to move between a first position sealing the bypass port and a second position sealing the primary exhaust outlet, Wherein under cold start, long idle and / or low main catalytic converter temperature conditions, the dual-acting valve assembly is moved to the second position to direct exhaust gas flow through the bypass passage and the bypass catalytic converter to reduce emissions. 2 . The engine of claim 1 , further comprising a main outlet conduit configured to receive the exhaust flow from the exhaust manifold and define the main exhaust outlet.

3. The engine of claim 2, wherein the bypass port is formed in the main outlet duct. 4 . The engine of claim 2 , wherein the main outlet conduit is a separate and distinct component configured to be coupled to the cylinder head.

5. The engine of claim 4, wherein the main outlet duct is a turbine inlet.

6. The engine of claim 2, wherein the main outlet conduit includes a recessed first valve seat formed around the bypass port, and Wherein in the first position, the dual-acting valve assembly is configured to sit flush within the recessed first valve seat to facilitate preventing obstruction of exhaust gas flow within the main outlet conduit.

7. The engine of claim 6, wherein the main outlet duct further comprises a recessed second valve seat formed around the main exhaust outlet, and Wherein in the second position, the dual-acting valve assembly is configured to sit flush within the recessed second valve seat to facilitate preventing obstruction of exhaust gas flow within the main outlet conduit.

8. The engine of claim 2, wherein the double-acting valve assembly includes a valve coupled to a valve shaft.

9. The engine of claim 8, wherein the valve shaft is rotatably located within a bore formed in the main outlet conduit, the valve shaft being rotatable to move the valve to the first position to seal the bypass port and to the second position to seal the main exhaust outlet.

10. The engine of claim 9, further comprising an actuator assembly operably coupled to the valve shaft to rotate the valve shaft within the bore.

11. The engine of claim 10, further comprising a turbocharger, wherein the actuator assembly is coupled to the turbocharger, and wherein an actuator linkage is operably coupled between the actuator assembly and the valve shaft for selective rotation thereof.

12. The engine of claim 1, wherein the bypass passage is an external conduit, the external conduit comprising a first conduit, a bypass catalyst conduit, and a second conduit, wherein the first conduit is fluidly coupled to the bypass port and is configured to supply exhaust gas to the bypass catalyst conduit including the bypass catalytic converter, and The second conduit is fluidly coupled between the bypass catalyst conduit and a bypass flow inlet of the main exhaust aftertreatment system.

13. The engine of claim 12, wherein the bypass flow inlet is formed in a main exhaust duct of the main exhaust aftertreatment system, and The bypass inlet is located upstream of the main catalytic converter.

14. The engine of claim 13, wherein the bypass flow inlet is located downstream of a turbocharger outlet.

15. The engine of claim 13, wherein the bypass flow inlet is oriented to direct exhaust gas flow onto an upstream face of the main catalytic converter to accelerate heating thereof.

16. The engine of claim 1, wherein the bypass port is formed in a collector portion of the exhaust manifold.

17. The engine of claim 16, wherein the bypass passage is integrally formed in the cylinder head.

18. The engine of claim 17, further comprising a water jacket formed in the cylinder head adjacent to a bypass catalyst conduit accommodating the bypass catalytic converter, Wherein the water jacket is configured to circulate a coolant to provide cooling to the bypass catalytic converter.

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