An air cleaner for an internal combustion engine includes a first housing having an inlet and an upper opening, a second housing having an outlet and a lower opening, a filter element arranged between the upper opening of the first housing and the lower opening of the second housing. The first housing includes a sound reducing wall portion. The sound reducing wall portion has a sound absorbing layer, which is made of nonwoven fabric, and an inner covering layer, which is fixed to the inner surface of the sound absorbing layer and made of a material having a lower air permeability than that of the sound absorbing layer.

An air cleaner for an internal combustion engine includes a first housing having an inlet and an upper opening, a second housing having an outlet and a lower opening, a filter element arranged between the upper opening of the first housing and the lower opening of the second housing. The first housing includes a sound reducing wall portion. The sound reducing wall portion has a sound absorbing layer, which is made of nonwoven fabric, and an inner covering layer, which is fixed to the inner surface of the sound absorbing layer and made of a material having a lower air permeability than that of the sound absorbing layer.

In an air cleaner, an air cleaner case having an upper opening which opens upward is formed. The air cleaner case is formed of a front wall, a rear fender, and right and left side covers. The upper opening is closed by a seat. A sound absorbing member is bonded to a bottom plate of the seat and housed in an air cleaner space. The intake noise in the air cleaner is absorbed by the sound absorbing member.

An air cleaner for an internal combustion engine is arranged to reduce intake noise. The air cleaner includes an air cleaner element for cleaning an intake air, and an elastic member for reducing intake noise by utilizing an inside space of the air cleaner. An inside space of the elastic member is in communication with the inside space of the air cleaner through a communication passage. Preferably, a surrounding space formed between the elastic member and a case portion for receiving the elastic member is opened to the outside.

An air cleaner for an internal combustion engine is arranged to reduce intake noise. The air cleaner includes an air cleaner element for cleaning an intake air, and an elastic member for reducing intake noise by utilizing an inside space of the air cleaner. An inside space of the elastic member is in communication with the inside space of the air cleaner through a communication passage. Preferably, a surrounding space formed between the elastic member and a case portion for receiving the elastic member is opened to the outside.

A construction machine includes: a partition member partitioning an accommodation space in an engine compartment into a main chamber and an intake chamber while having an inter-chamber opening; a fan disposed in the main chamber to generate cooling air flowing through an air intake opening, the intake chamber, the inter-chamber opening, and the main chamber in this order by sucking air in the engine compartment in a suction direction; a duct joined to an outer wall to enclose the air intake opening and including an inner peripheral surface enclosing a duct passage leading to the air intake opening and an outer peripheral surface. The duct extends in a duct extension direction different from the suction direction of the fan, disposed in the intake chamber to define a duct surrounding space around the outer peripheral surface of the duct.

A construction machine includes: a partition member partitioning an accommodation space in an engine compartment into a main chamber and an intake chamber while having an inter-chamber opening; a fan disposed in the main chamber to generate cooling air flowing through an air intake opening, the intake chamber, the inter-chamber opening, and the main chamber in this order by sucking air in the engine compartment in a suction direction; a duct joined to an outer wall to enclose the air intake opening and including an inner peripheral surface enclosing a duct passage leading to the air intake opening and an outer peripheral surface. The duct extends in a duct extension direction different from the suction direction of the fan, disposed in the intake chamber to define a duct surrounding space around the outer peripheral surface of the duct.

An intake device of an engine includes an air cleaner and an air flow sensor. The air cleaner includes an air filter, a cleaner case which forms a primary side space above the air filter and a secondary side space below the air filter, an inlet duct, and an outlet duct. The air flow sensor is fixed to the outlet duct. The cleaner case has a first side wall on which the inlet duct is mounted, and a second side wall which opposedly faces the first side wall. The air filter has a folded shape like bellows, and is held in the cleaner case. The second side wall has a deflecting portion which deflects air introduced from the inlet duct into a flow directed in an obliquely upward direction.

An intake device of an engine includes an air cleaner and an air flow sensor. The air cleaner includes an air filter, a cleaner case which forms a primary side space above the air filter and a secondary side space below the air filter, an inlet duct, and an outlet duct. The air flow sensor is fixed to the outlet duct. The cleaner case has a first side wall on which the inlet duct is mounted, and a second side wall which opposedly faces the first side wall. The air filter has a folded shape like bellows, and is held in the cleaner case. The second side wall has a deflecting portion which deflects air introduced from the inlet duct into a flow directed in an obliquely upward direction.

A cowling for an outboard motor has port and starboard intake ports that direct flow of intake air into the cowling and extend downwardly along the aftward side of the cowling and face laterally outwardly. A duct system receives and conveys intake air intake ports to an intake conduit for the outboard motor. The duct system includes port and starboard intake troughs that extend alongside the intake ports and redirect the intake air from a generally lateral flow into the intake ports to a generally vertically downward flow and then to a generally forward flow towards the intake conduit. Port and starboard baffles that extend alongside the intake ports and direct flow of water into port and starboard channels located alongside the baffles, respectively. The channels drain the water by gravity depending on tilt and trim orientation of the outboard motor.