An outboard motor catalytic converter that can downsize an outboard motor by making a space, where catalysts are installed, small and can ensure efficient reaction of the catalysts. The outboard motor catalytic converter includes exhaust pipes that are connected to exhaust manifolds of an engine of the outboard motor. Catalysts are installed inside the exhaust pipes, and at least a portion of each of the exhaust pipes, which corresponds to a place where the catalysts are installed, is formed to have a double structure constituted of an inner pipe and an outer pipe.

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.

An exhaust gas purification structure of an outboard motor includes an exhaust gas pipe that has an exhaust gas passage through which exhaust gas of an engine can flow; and a catalyst that is provided in the exhaust gas passage and purifies the exhaust gas by allowing the exhaust gas to pass through the inside thereof. The exhaust gas pipe includes a coolant flow passage allowing a coolant that cools the exhaust gas to flow therethrough. An exhaust gas bypass passage allowing the exhaust gas to flow without passing through the catalyst is formed between the catalyst and an inner surface of the exhaust gas pipe forming the exhaust gas passage.

An outboard includes a plurality of first branched pipes connected to a plurality of first exhaust ports and a plurality of second branched pipes connected to a plurality of second exhaust ports, respectively, wherein the plurality of first branched pipes are connected to a first collecting pipe and the plurality of second branched pipes are connected to a second collecting pipe. A connector connects the first collecting pipe and the second collecting pipe. The plurality of first branched pipes extend in a direction away from the connector in a plan view, and each includes a first exhaust pathway located farther away from the connector than the first collecting pipe is in the plan view. The plurality of second branched pipes extend in a direction away from the connector in a plan view, and each includes a second exhaust pathway located farther away from the connector than the second collecting pipe.

An outboard motor that controls combustion in an engine according to a purification rate by a catalyst and is capable of performing efficient engine combustion. The outboard motor includes a catalyst provided in an exhaust manifold of an engine and a second catalyst provided in an exhaust pipe, an air-fuel ratio sensor and an O2 sensor, which are located on an upstream side and a downstream side of the catalyst, respectively, and a controller for controlling combustion in the engine. The controller calculates an exhaust gas purification rate based on a value detected by the air-fuel ratio sensor or the O2 sensor and controls the combustion in the engine so as to make the exhaust gas purification rate appropriate.

An outboard motor that significantly reduces or prevents discoloration around an exhaust opening includes an engine, a drive shaft, a propeller shaft, a housing, an exhaust passage, a water intake passage, and a valve. The exhaust passage guides an exhaust gas from the engine toward the discharge chamber inside the housing. The water intake passage guides water, which enters an inside of the housing, to the discharge chamber when a forward propulsive force is generated. The valve regulates passage of the exhaust gas at the first opening due to water pressure when a forward propulsive force is generated. The valve permits the passage of exhaust gas at the first opening due to exhaust pressure when a backward propulsive force is generated.

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.

An outboard motor that significantly reduces or prevents discoloration around an exhaust hole includes an engine, a drive shaft, a propeller shaft, a housing, a discharge passage, and non-metal covers. The housing includes a discharge outlet to discharge an exhaust gas of the engine and the cooling water of the engine. The discharge passage guides the exhaust gas and the cooling water from the engine toward the discharge outlet. The covers are detachably attached to the housing so as to cover the discharge outlet and include at least one exhaust opening.

An outboard motor (10) includes a V-engine (20) having a left bank (BL) and a right bank (BR) extending obliquely toward a rear left side and a rear right side, respectively, relative to a crankshaft (21) extending in a vertical direction. An intake device (18) is provided between the left bank and the right bank, and catalyst devices (62L, 62R) that treat exhaust gas are disposed rearward of cylinder heads (24L, 24R) of the left bank and the right bank.

A cooling system is for cooling a marine engine having an engine block and a cylinder head, and a supercharger configured to provide charge air for combustion in the marine engine. The cooling system has a charge air cooler configured to cool the charge air prior to combustion in the marine engine. The cooling system is configured to circulate cooling water from a body of water in which the marine engine is operating to the marine engine and then back to the body of water. The cooling system is further configured to convey the cooling water in parallel to the marine engine and the charge air cooler. A sprayer is configured to spray the cooling water into exhaust gas discharged from the marine engine. The cooling system is configured to convey the cooling water in series to the charge air cooler and then to the sprayer.