An air intake and exhaust system for a marine engine having an intake manifold and an exhaust manifold includes an air compressor configured to compress ambient air into compressed air and a catalytic converter assembly configured to convert pollutants in an exhaust gas stream received from the exhaust manifold. The air compressor is configured to be fluidly coupled to the intake manifold of the engine for directing at least a first portion of the compressed air to the intake manifold of the engine. The air compressor is also selectively fluidly coupled to the catalytic converter assembly for selectively directing a second portion of the compressed air into the exhaust gas stream at a secondary air injection location at or upstream of the catalytic converter assembly.

The disclosure relates to a method and a device for diagnosing coking of a secondary air system of an internal combustion engine. The secondary air system has an intake air line for providing secondary air, a secondary air pump for compressing the secondary air, a secondary air valve for controlling the secondary air injection, a pressure sensor that is arranged in the secondary air system downstream of the secondary air pump and upstream of the secondary air valve, and an injection line for injecting the secondary air into an exhaust tract of the internal combustion engine.

A secondary air introduction device is configured to supply air into an exhaust passage of an engine to combust unburned gas contained in exhaust gas. The secondary air introduction device includes: an air introduction passage configured to introduce air into the exhaust passage; and a secondary air valve configured to be attached to an outer surface of a cylinder head of the engine and to control opening and closing of the air introduction passage. The secondary air valve is configured to be attached to an outer lateral surface of the cylinder head on one side in an axial direction of a crankshaft, and the secondary air valve includes an air introduction inlet formed in a position opposite to the outer lateral surface of the cylinder head in the axial direction of the crankshaft.

A heat shield includes an outer jacket including a fluid inlet port and a fluid outlet port, and an inner jacket nested within the outer jacket and spaced apart therefrom to define a fluid passageway therebetween. The fluid passageway is in fluid communication with the fluid inlet port and the fluid outlet port for directing a cooling fluid from the fluid inlet port to the fluid outlet port through the fluid passageway. The inner jacket at least partially defines a main cavity configured to at least partially protect a turbocharger of the marine engine.

A secondary air introduction device is configured to supply air into an exhaust passage of an engine to combust unburned gas contained in exhaust gas. The secondary air introduction device includes: an air introduction passage configured to introduce air into the exhaust passage; and a secondary air valve configured to be attached to an outer surface of a cylinder head of the engine and to control opening and closing of the air introduction passage. The secondary air valve is configured to be attached to an outer lateral surface of the cylinder head on one side in an axial direction of a crankshaft, and the secondary air valve includes an air introduction inlet formed in a position opposite to the outer lateral surface of the cylinder head in the axial direction of the crankshaft.

The present invention relates to an exhaust gas purification system comprising two catalytic sub-systems, wherein the first catalytic sub-system is for conversion of NOx, HC, CO and optionally particulate matter, and the second sub-system is for conversion of CO. The second sub-system locates at the downstream of the first catalytic sub-system. An air injection is positioned between the first catalytic sub-system and second catalytic sub-system.

Methods and systems are provided for improving catalyst temperature control while reducing oxygen saturation. Secondary air is injected at a location downstream of the catalyst during selected conditions. A mixing valve position is coordinated with the air injection to improve local turbulence and thereby enhance air and fuel mixing in the exhaust passage, in at least one arrangement.

An exhaust purification system for the reduction of emissions from an exhaust stream, including an oxygen detection system; a catalyst; and an air injection system positioned between the oxygen detection system and the catalyst to inject air into the exhaust stream at designated exhaust conditions, to protect the catalyst from oxygen-deprived conditions.

An air intake and exhaust system for a marine engine having an intake manifold and an exhaust manifold includes an air compressor configured to compress ambient air into compressed air and a catalytic converter assembly configured to convert pollutants in an exhaust gas stream received from the exhaust manifold. The air compressor is configured to be fluidly coupled to the intake manifold of the engine for directing at least a first portion of the compressed air to the intake manifold of the engine. The air compressor is also selectively fluidly coupled to the catalytic converter assembly for selectively directing a second portion of the compressed air into the exhaust gas stream at a secondary air injection location at or upstream of the catalytic converter assembly.

A heat shield includes an outer jacket including a fluid inlet port and a fluid outlet port, and an inner jacket nested within the outer jacket and spaced apart therefrom to define a fluid passageway therebetween. The fluid passageway is in fluid communication with the fluid inlet port and the fluid outlet port for directing a cooling fluid from the fluid inlet port to the fluid outlet port through the fluid passageway. The inner jacket at least partially defines a main cavity configured to at least partially protect a turbocharger of the marine engine.