A silencer having an outer housing; and a central perforated tube through which air flows. The silencer further includes an additional perforated structure located between the central perforated tube and the outer housing, a first chamber is formed between the central perforated tube and the additional perforated structure, and the additional perforated structure is configured such that at least one second chamber is formed, which is at least partially located radially outside of the first chamber, where the second chamber is communicated with the first chamber by perforates. The disclosure further relates to a vehicle engine having the silencer. The silencer is compact in structure, and has a better broadband silencing effect.

There is provided a muffling apparatus capable of sufficiently reducing noise, achieving space saving, and suppressing an increase in air-flow resistance in a suction passage. In a muffling apparatus including a resonator main body having a predetermined volume and a communication tube that allows the resonator main body to communicate with a suction passage of an internal combustion engine, the communication tube includes a first communication tube having one end that communicates with the suction passage, a second communication tube having one end that communicates with the resonator main body, and a continuous section that communicates with other ends of the first and second communication tubes, and a third communication tube is formed at the continuous section.

A variable noise attenuation element includes at least two tube sections that define an overall tube length that defines a first effective length and associated first peak frequency for noise attenuation, and a valve having a valve member. The valve joins the tube sections together and includes openings that permit communication between the tube sections when the valve is in an open configuration. The valve member operates to close the opening in response to a predetermined vacuum level within the tube sections to define a second tube effective length and associated second peak frequency for attenuation that is less than the overall length. A method of attenuating noise in a vehicle using a passive attenuation arrangement operates a valve disposed between two tube sections to change an effective length of the tube and associated peak frequencies for attenuation in response to an engine operating parameter.

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 internal combustion engine comprising: a plurality of cylinders; at least one intake manifold, which receives fresh air from the outside; a plurality of intake channels, each connecting a cylinder to the intake manifold; and an intake sound amplification device, which is provided with an amplification pipe, an insulating element sealing the amplification pipe in a tight manner, a plurality of amplification channels, each originating from a corresponding intake channel, and an amplification manifold, which, on one side, is connected to all amplification channels and, on the other side, is connected to the amplification pipe.

An air duct for a vehicle functions to reduce intake noise and includes an outer housing configured having a pipe shape so that outside air is introduced into an engine therethrough. The air duct also has an inner pipe fixed in the outer housing so that an outer surface of the inner pipe is spaced apart from an inner surface of the outer housing, thereby partitioning the inside of the outer housing in a radial direction. A space between the inner pipe and the outer housing communicates with the inside of the inner pipe.

An air induction system for a vehicle internal combustion engine has an air filter box that couples with the internal combustion engine. A tuner, in the air filter box, removes offending lower frequency noise generated by the internal combustion engine. An air filter is positioned in the air filter box to filtering air entering the internal combustion engine.

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 30200 Hz and the secondary resonance frequency is set to 50300 Hz.

An air induction system for attenuating sound produced by an engine, a housing defining a working chamber for attenuating sound produced by the engine. The air induction system further includes a tube having a first end extending into the working chamber and a second end to be in fluid communication with the engine. The air induction system further includes a first flange radially extending from the tube and disposed in the working chamber. The tube, the housing and the first flange cooperate to define a resonator operable to attenuate sound produced by the engine.

A resonator for attenuating sound waves produced by an engine includes a resonator housing and a neck. The neck includes an outer shell extending from the resonator housing providing fluid communication between the resonator housing and an air duct. The neck further includes a partition disposed in the outer shell. The partition cooperates with the outer shell to define a plurality of distinct air paths, each air path in fluid communication with a distinct resonance chamber of the plurality of resonance chambers. The resonator is operable to attenuate or change the characteristics of sound waves produced by the engine.