Abstract: A head cover structured and arranged to cover at least part of a face of a cylinder head of an internal combustion engine is described. The head cover includes a chamber formation part structured and arranged to provide a chamber to restrain sound propagating through air from the cylinder head. The chamber formation part includes a partition part for partitioning the chamber from a space on a cylinder head side. The partition part has a convex part projecting into the chamber, and a through hole may be provided in the convex part that penetrates from the space on the cylinder head side to the chamber.

Abstract: A head cover structured and arranged to cover at least part of a face of a cylinder head of an internal combustion engine is described. The head cover includes a chamber formation part structured and arranged to provide a chamber to restrain sound propagating through air from the cylinder head. The chamber formation part includes a partition part for partitioning the chamber from a space on a cylinder head side. The partition part has a convex part projecting into the chamber, and a through hole may be provided in the convex part that penetrates from the space on the cylinder head side to the chamber.

Abstract: 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.

Abstract: Intake sound reduction device for internal combustion engine includes an elastic member formed into substantially cylindrical shape and having an open base end, a top end sealed by an end surface wall and a bellows circumferential wall; a base plate retaining base end of elastic member; and a communication pipe whose one end is connected to base plate so that a volume chamber formed inside elastic member communicates with an intake passage of the engine. Intake sound reduction device has first resonance system formed by expansion and contraction in axial direction of elastic member and second resonance system formed by film-vibration of end surface wall. When either one of resonance frequencies of the first and second resonance systems is primary resonance frequency and the other is secondary resonance frequency, the primary resonance frequency is set to 30˜200 Hz and the secondary resonance frequency is set to 50˜300 Hz.

Abstract: 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.

Abstract: Intake sound reduction device for internal combustion engine includes an elastic member formed into substantially cylindrical shape and having an open base end, a top end sealed by an end surface wall and a bellows circumferential wall; a base plate retaining base end of elastic member; and a communication pipe whose one end is connected to base plate so that a volume chamber formed inside elastic member communicates with an intake passage of the engine. Intake sound reduction device has first resonance system formed by expansion and contraction in axial direction of elastic member and second resonance system formed by film-vibration of end surface wall. When either one of resonance frequencies of the first and second resonance systems is primary resonance frequency and the other is secondary resonance frequency, the primary resonance frequency is set to 30˜200 Hz and the secondary resonance frequency is set to 50˜300 Hz.

Abstract: An intake sound generation apparatus for an internal combustion engine, including an introduction duct connected to an intake passage of an intake system of the engine, a vibration member including a diaphragm portion which is vibrated by intake pulsation in the intake system, and a bellows portion configured to promote vibration of the diaphragm portion, the vibration member being so disposed as to cover one end of the introduction duct, and a resonance duct having one end connected to the introduction duct through the vibration member and the other end opened to an outside of the intake sound generation apparatus, the resonance duct acting to increase and emit a sound pressure of intake sound produced by vibration of the vibration member. A central axis of at least one of the introduction duct and the resonance duct is located offset relative to a central axis of the vibration member.

Abstract: An intake sound generation apparatus for an internal combustion engine, including an introduction duct connected to an intake passage of an intake system of the engine, a vibration member including a diaphragm portion which is vibrated by intake pulsation in the intake system, and a bellows portion configured to promote vibration of the diaphragm portion, the vibration member being so disposed as to cover one end of the introduction duct, and a resonance duct having one end connected to the introduction duct through the vibration member and the other end opened to an outside of the intake sound generation apparatus, the resonance duct acting to increase and emit a sound pressure of intake sound produced by vibration of the vibration member. A central axis of at least one of the introduction duct and the resonance duct is located offset relative to a central axis of the vibration member.