A first fuel addition valve disposed in a portion of a first exhaust passage upstream from a first upstream purification device, a first urea addition valve disposed in a portion of the first exhaust passage between the first upstream purification device and a first downstream purification device, and a first valve cooling passage configured such that i) refrigerant passes the first urea addition valve and the first fuel addition valve in order, and ii) the refrigerant cools the first fuel addition valve after the refrigerant cools the first urea addition valve.

A marine propulsion device includes an engine, an exhaust pipe to allow exhaust gas of the engine to pass through the exhaust pipe, and a cooling water supply passage to supply cooling water for the engine into the exhaust pipe toward a downstream side in a flow direction of the exhaust gas and cause the cooling water to flow circumferentially along an inner peripheral surface of the exhaust pipe.

An object of this invention is to efficiently warm up a catalyst and keep its temperature. Provided is a drive system, including: an internal combustion engine; a catalytic unit configured to purify an exhaust gas from the internal combustion engine; a motor used for at least one of drive or regeneration; and a flow path formed so as to allow an oil-based medium for lubricating the motor to flow in the vicinity of the catalytic unit. The oil-based medium is heated in the motor and exchanges heat in the catalytic unit to heat the catalytic unit.

A utility vehicle includes an exhaust assembly fluidly coupled to an engine. Depending on various parameters, such as the size and/or performance of the vehicle, the exhaust assembly is required to meet certain emissions regulations. Such emissions regulations may be met by increasing the temperature within the exhaust assembly, however, at particularly high temperatures, a catalyst of the exhaust assembly may be damaged. Therefore, the exhaust assembly includes various options for cooling portions thereof to remove heat from the assembly.

An exhaust conduit for a marine exhaust system includes an inlet end portion connectable to an exhaust manifold, an outlet end portion that directs exhaust gases toward an exhaust system outlet, a catalytic converter assembly arranged between the inlet and outlet end portions, and inner and outer tubes. The inner tube directs exhaust gases from the exhaust manifold to the catalytic converter assembly, and the outer tube surrounds the inner tube to define a cooling liquid passage between the inner and outer tubes. A flange is secured to the inner and outer tubes at inlet ends thereof, the flange being connectable to an outlet of the exhaust manifold. The inner tube has a uniform diameter between the flange and the catalytic converter assembly, and is welded to the flange independently of the outer tube. First and second welds join the inner and outer tubes to the flange at radially inner and outer faces, respectively, of a flange rim.

An exhaust system is for a marine propulsion device having an internal combustion engine. A catalyst housing has a housing inlet end that receives an exhaust gas flow from the internal combustion engine into the catalyst housing and an opposite, housing outlet end that discharges the exhaust flow out of the catalyst housing. A catalyst is disposed in the catalyst housing. The catalyst has a catalyst inlet end that receives the exhaust gas flow and an opposite, catalyst outlet end that discharges the exhaust gas flow. A catalyst mantel is on an outer periphery of the catalyst. The catalyst mantel has a mantel inlet end and an opposite, mantel outlet end. A radial flange is on at least one of the mantel outlet end and mantel inlet end. A connector mates with an inner diameter of the catalyst housing. The radially extending flange of the catalyst mantel is axially sandwiched between the connector and a radially inner shoulder of the catalyst housing.

An outboard motor includes a catalyst housing passage disposed inside the V-shaped line, a cooling water passage including at least a portion disposed at a periphery of a catalyst and that guides cooling water that cools an exhaust passage and a vent hole disposed higher than the catalyst and that connects the interior of the cooling water passage to the exterior of the cooling water passage.

Disclosed is an exhaust manifold that comprises an exhaust gas passage, an EGR passage, and a coolant passage. The exhaust gas passage extends fluidly between an exhaust gas inlet and an exhaust gas outlet positioned downstream thereof. The EGR passage extends fluidly between an EGR inlet and an EGR outlet positioned downstream thereof. The EGR inlet is defined by the exhaust gas passage. A coolant passage extends fluidly between a coolant inlet and a coolant outlet positioned downstream thereof. The coolant passage overlaps the exhaust gas passage and the EGR passage. The exhaust gas passage is configured to cool the exhaust gas, and EGR passage is configured to cool the recirculated portion of the exhaust gas.

A marine muffler capable of handling both marine engine exhaust gas and marine engine cooling water includes a double wall baffle partitioning the muffler interior so as to function as a cooling water conduit. The cooling water conduit includes an inlet disposed external to the main muffler housing and an outlet configured and disposed so as to discharge the engine cooling water into the exhaust duct connected to the muffler outlet. The muffler is thus able to convey the engine cooling water through the muffler housing within a dedicated conduit while maintaining the cooling water separate from the exhaust gas. A muffler that is adapted to handle both the exhaust and cooling water flowing from a marine engine allows for the elimination of engine cooling water piping.

An open loop cooling water system is for a marine engine. A cooling water inlet receives cooling water from a body of water. A cooling water outlet discharges the cooling water back to the body of water. A cooling water circuit conveys cooling water from the cooling water inlet, through the marine engine, and to the cooling water outlet. A cooling water pump that pumps cooling water from upstream to downstream through the cooling water circuit. A recirculation pump that is located in the cooling water circuit downstream of at least one component of the marine engine and upstream of the cooling water outlet. The recirculation pump is configured to pump cooling water from downstream of the marine engine back into the cooling water circuit upstream of the marine engine. Methods are for cooling a marine engine using an open loop cooling system.