Marine engine exhaust system having secondary air injection

An assembly for a marine craft comprising:

• a marine engine having an intake manifold and an exhaust manifold;
• an air compressor configured to compress ambient air into compressed air;
• and
• a catalytic converter assembly including a catalyst element positioned downstream of and in fluid communication with an exhaust conduit, the catalytic converter assembly being configured to convert pollutants in an exhaust gas stream received from the exhaust manifold of the engine,
• a controller,
• a first oxygen sensor in operative communication with the controller and configured to detect an oxygen level of the exhaust gas stream upstream from the secondary air inlet of the exhaust conduit,
• a second oxygen sensor in operative communication with the controller and configured to detect an oxygen level of the exhaust gas stream downstream from the catalytic converter assembly, wherein the controller compares oxygen levels detected by the second oxygen sensor to oxygen levels taken by the first oxygen sensor to determine whether the catalyst element is effectively removing toxic pollutants from the exhaust gas stream,
• wherein the air compressor is fluidly coupled to an intercooler having an intercooler outlet conduit in fluid communication with the intake manifold of the engine for directing at least a first portion of the compressed air to the intake manifold of the engine, and wherein the intercooler outlet conduit has a secondary air outlet, the secondary air outlet being joined to a secondary air injection conduit, the secondary air injection conduit bypassing the marine engine and terminating in a secondary air inlet of the exhaust conduit for selectively directing a second portion of the compressed air into the exhaust gas stream to the secondary air inlet of the exhaust conduit upstream from the catalytic converter assembly.

An assembly for a marine craft comprising:

• a marine engine having an intake manifold and an exhaust manifold;
• a turbocharger comprising a turbine positioned downstream and in fluid communication with the exhaust manifold for receiving exhaust gases expelled therefrom, the turbocharger further comprising an air compressor configured to compress ambient air into compressed air,
• a catalytic converter assembly positioned downstream of and in fluid communication with an exhaust conduit, the catalytic converter assembly being configured to convert pollutants in an exhaust gas stream received from the exhaust manifold of the engine,
• an intercooler fluidly coupled to the air compressor and having an intercooler outlet conduit in fluid communication with the intake manifold of the engine for directing at least a first portion of the compressed air to the intake manifold of the engine,
• wherein the intercooler outlet conduit has a secondary air outlet downstream of the intercooler, the secondary air outlet being joined to a secondary air injection conduit, the secondary air injection conduit bypassing the marine engine and terminating in a secondary air inlet of the exhaust conduit for selectively directing a second portion of the compressed air into the exhaust gas stream at or upstream from the catalytic converter assembly,
• a valve positioned in-line with the secondary air injection conduit, the valve being movable between at least one open position and a closed position by a controller, wherein secondary air flows through the secondary air injection conduit when the valve is in the at least one open position and does not flow through the secondary air injection conduit when the valve is in the closed position,
• a first oxygen sensor in operative communication with the controller and configured to detect an oxygen level of the exhaust gas stream upstream from the secondary air inlet of the exhaust conduit, and
• a second oxygen sensor in operative communication with the controller and configured to detect an oxygen level of the exhaust gas stream downstream from the catalytic converter assembly, wherein the controller compares oxygen levels detected by the second oxygen sensor to oxygen levels taken by the first oxygen sensor to determine whether the catalytic converter assembly is effectively removing toxic pollutants from the exhaust gas stream.

An assembly for a marine craft comprising:

• a marine engine having an intake manifold and an exhaust manifold;
• a turbocharger comprising a turbine positioned downstream and in fluid communication with the exhaust manifold for receiving exhaust gases expelled therefrom, the turbocharger further comprising an air compressor configured to compress ambient air into compressed air,
• a catalytic converter assembly positioned downstream of and in fluid communication with an exhaust conduit, the catalytic converter assembly being configured to convert pollutants in an exhaust gas stream received from the exhaust manifold of the engine,
• an intercooler fluidly coupled to the air compressor and having an intercooler outlet conduit in fluid communication with the intake manifold of the engine for directing at least a first portion of the compressed air to the intake manifold of the engine,
• wherein the intercooler outlet conduit has a secondary air outlet downstream of the intercooler, the secondary air outlet being joined to a secondary air injection conduit, the secondary air injection conduit bypassing the marine engine and terminating in a secondary air inlet of the exhaust conduit for selectively directing a second portion of the compressed air into the exhaust gas stream at or upstream from the catalytic converter assembly,
• a valve positioned in-line with the secondary air injection conduit, the valve being movable between at least one open position and a closed position by a controller, wherein secondary air flows through the secondary air injection conduit when the valve is in the at least one open position and does not flow through the secondary air injection conduit when the valve is in the closed position,
• a first oxygen sensor in operative communication with the controller and configured to detect an oxygen level of the exhaust gas stream upstream from the secondary air inlet of the exhaust conduit, and
• a second oxygen sensor in operative communication with the controller and configured to detect an oxygen level of the exhaust gas stream downstream from the catalytic converter assembly, wherein the controller compares oxygen levels detected by the second oxygen sensor to oxygen levels taken by the first oxygen sensor to determine whether to open or close the valve.

An assembly for a marine craft comprising:

• a marine engine having an intake manifold and an exhaust manifold;
• an exhaust conduit in fluid communication with the exhaust manifold,
• a catalytic converter assembly positioned downstream of and in fluid communication with the exhaust conduit, the catalytic converter assembly being configured to convert pollutants in an exhaust gas stream received from the exhaust manifold of the engine,
• an intercooler having an intercooler outlet conduit in fluid communication with the intake manifold of the engine for directing at least a first portion of compressed air to the intake manifold of the engine,
• wherein the intercooler outlet conduit has a secondary air outlet downstream of the intercooler, the secondary air outlet being joined to a secondary air injection conduit, the secondary air injection conduit bypassing the marine engine and terminating in a secondary air inlet of the exhaust conduit for selectively directing a second portion of compressed air into the exhaust gas stream upstream from the catalytic converter assembly, and
• a valve positioned in-line with the secondary air injection conduit, the valve being movable between at least one open position and a closed position by a controller, wherein secondary air flows through the secondary air injection conduit when the valve is in the at least one open position;
• and
• a first oxygen sensor in operative communication with the controller and configured to detect an oxygen level of the exhaust gas stream upstream from the secondary air inlet of the exhaust conduit,
• a second oxygen sensor in operative communication with the controller and configured to detect an oxygen level of the exhaust gas stream downstream from the catalytic converter assembly, wherein the controller compares oxygen levels detected by the second oxygen sensor to oxygen levels taken by the first oxygen sensor to determine whether to open or close the valve.