Cold start catalyst bypass system
An internal combustion engine system includes an internal combustion engine with a plurality of combustion chambers each having a main exhaust valve and a cold start exhaust valve, a main exhaust aftertreatment system with a main catalytic converter configured to receive exhaust gas from the internal combustion engine via the main exhaust valves and an exhaust manifold, and a light-off catalyst bypass system with a bypass passage and a bypass catalytic converter configured to selectively receive exhaust gas from the internal combustion engine via the cold start exhaust valves. A controller is programmed to determine a cold start, long idle, and/or low main catalytic converter temperature condition, deactivate the main exhaust valves to facilitate preventing exhaust gas flow through the exhaust manifold, and activate the cold start exhaust valves to enable exhaust gas flow through the bypass passage and the bypass catalytic converter.
1 . An internal combustion engine system, comprising:
an internal combustion engine with a plurality of combustion chambers each having a main exhaust valve and a cold start exhaust valve;
a main exhaust aftertreatment system with a main catalytic converter configured to receive exhaust gas from the internal combustion engine via the main exhaust valves and an exhaust manifold;
a light-off catalyst bypass system with a bypass passage and a bypass catalytic converter configured to selectively receive exhaust gas from the internal combustion engine via the cold start exhaust valves; and
a controller having one or more processors and a non-transitory computer-readable storage medium having a plurality of instructions stored thereon, which, when executed by the one or more processors, cause the one or more processors to perform operations comprising:
determine a cold start, long idle, and/or low main catalytic converter temperature condition;
deactivate the main exhaust valves to facilitate preventing exhaust gas flow through the exhaust manifold; and
activate the cold start exhaust valves to enable exhaust gas flow through the bypass passage and the bypass catalytic converter.
2 . The internal combustion engine system of claim 1 , further comprising a turbocharger including a turbine configured to receive exhaust gas from the exhaust manifold.
3 . The internal combustion engine system of claim 2 , wherein the exhaust manifold is configured to supply exhaust gas through a main outlet duct and the turbine, and then to the main exhaust aftertreatment system and the main catalytic converter.
4 . The internal combustion engine system of claim 3 , wherein the bypass passage is configured to supply exhaust gas to a location in the main outlet duct upstream of the turbine.
5 . The internal combustion engine system of claim 3 , wherein the bypass passage is configured to supply exhaust gas to a location in a main exhaust conduit downstream of the turbine and upstream of the main catalytic converter.
6 . The internal combustion engine system of claim 1 , wherein each combustion chamber includes:
a main exhaust port selectively closed by the main exhaust valve; and
a cold start exhaust port selectively closed by the cold start exhaust valve.
7 . The internal combustion engine system of claim 6 , wherein each cold start exhaust port is configured to supply exhaust gas to a cold start exhaust passage fluidly connected to the bypass passage.
8 . The internal combustion engine system of claim 1 , further comprising a switchable valvetrain configured to selectively deactivate the main exhaust valves and selectively deactivate the cold start exhaust valves.
9 . The internal combustion engine system of claim 8 , wherein deactivating the main exhaust valves moves the main exhaust valves to a closed position, and
wherein deactivating the cold start exhaust valves moves the cold start exhaust valves to a closed position.
10 . The internal combustion engine system of claim 8 , wherein the switchable valvetrain includes an exhaust camshaft operably associated with the main exhaust valves and the cold start exhaust valves.
11 . A method of operating an internal combustion engine system that comprises:
an internal combustion engine with a plurality of combustion chambers each having a main exhaust valve and a cold start exhaust valve;
a main exhaust aftertreatment system with a main catalytic converter configured to receive exhaust gas from the internal combustion engine via the main exhaust valves and an exhaust manifold;
a light-off catalyst bypass system with a bypass passage and a bypass catalytic converter configured to selectively receive exhaust gas from the internal combustion engine via the cold start exhaust valves; and
a controller configured to selectively activate/deactivate the main exhaust valves and the cold start exhaust valves, the method comprising:
monitoring, by the controller, a temperature of the main catalytic converter to determine if the temperature is below a predetermined light-off temperature;
deactivating, by the controller, the main exhaust valves when the main catalytic converter is below the predetermined light-off temperature, to thereby facilitate preventing exhaust gas flow through the exhaust manifold; and
activating, by the controller, the cold start exhaust valves when the main catalytic converter is below the predetermined light-off temperature, to thereby enable exhaust gas flow through the bypass passage and the bypass catalytic converter.
12 . The method of claim 11 , further comprising:
activating, by the controller, the main exhaust valves when the main catalytic converter has reached the predetermined light-off temperature, to thereby enable exhaust gas flow through the exhaust manifold; and
deactivating, by the controller, the cold start exhaust valves when the main catalytic converter has reached the predetermined light-off temperature, to thereby facilitate preventing exhaust gas flow through the bypass passage and the bypass catalytic converter.
13 . The method of claim 11 , wherein the internal combustion engine system further comprises a turbocharger including a turbine configured to receive exhaust gas from the exhaust manifold.
14 . The method of claim 13 , wherein the exhaust manifold is configured to supply exhaust gas through a main outlet duct and the turbine, and then to the main exhaust aftertreatment system and the main catalytic converter.
15 . The method of claim 14 , wherein the bypass passage is configured to supply exhaust gas to a location in the main outlet duct upstream of the turbine.
16 . The method of claim 14 , wherein the bypass passage is configured to supply exhaust gas to a location in a main exhaust conduit downstream of the turbine and upstream of the main catalytic converter.
17 . The method of claim 11 , wherein each combustion chamber includes:
a main exhaust port selectively closed by the main exhaust valve; and
a cold start exhaust port selectively closed by the cold start exhaust valve.
18 . The method of claim 17 , wherein each cold start exhaust port is configured to supply exhaust gas to a cold start exhaust passage fluidly connected to the bypass passage.
19 . The method of claim 11 , wherein the internal combustion engine system further includes a switchable valvetrain configured to selectively deactivate the main exhaust valves and selectively deactivate the cold start exhaust valves.
20 . The method of claim 19 , wherein deactivating the main exhaust valves moves the main exhaust valves to a closed position, and
wherein deactivating the cold start exhaust valves moves the cold start exhaust valves to a closed position.