An intake plenum is for a marine engine, the marine engine having first and second throttle devices for controlling flow of intake air to the marine engine. The intake plenum has an airbox providing an expansion volume, first and second inlets that convey the intake air in parallel to the expansion volume, first and second outlets that convey the intake air in parallel from the expansion volume to the first and second throttle devices, and first and second Helmholtz-style attenuator devices located at the first and second outlets, respectively. Together the first and second inlets, expansion volume, and first and second Helmholtz-style attenuator devices are configured to attenuate different frequencies of sound emanating from the marine engine via the first and second outlets.

A variable noise attenuation element is disclosed that comprises a tube, at least one valve seat, at least one valve body and a wire connected to the valve body. The tube has an overall length that defines a first effective length for noise attenuation. The valve seat is disposed in the tube. Retraction of the wire brings the valve body into engagement with the valve seat to selectively define a second effective length of the tube that is less than the overall length.

An intake plenum is for a marine engine, the marine engine having first and second throttle devices for controlling flow of intake air to the marine engine. The intake plenum has an airbox providing an expansion volume, first and second inlets that convey the intake air in parallel to the expansion volume, first and second outlets that convey the intake air in parallel from the expansion volume to the first and second throttle devices, and first and second Helmholtz-style attenuator devices located at the first and second outlets, respectively. Together the first and second inlets, expansion volume, and first and second Helmholtz-style attenuator devices are configured to attenuate different frequencies of sound emanating from the marine engine via the first and second outlets.

A rectification structural body includes an inlet port into which air from an air cleaner flows, an outlet port from which air flows out toward an airflow sensor, and a chamber provided between the inlet port and the outlet port. The inlet port and the outlet port are provided in such directions and at such positions that an air flow is bent in the chamber. The chamber includes two cases of a first case and a second case, the chamber being divided into the two cases.

A broad-band resonance silencer has an at least two-part housing which is designed to receive an exhaust-or gas-conveying pipe, which defines, with a circumferentially surrounding pipe jacket with acoustic openings formed therein, a pipe interior, wherein the pipe, in its installed position, is enclosed by a damping chamber formed by the housing, which chamber is actively connected to the pipe interior via the acoustic openings, and wherein the housing includes two axially split housing half-shells. In order to broaden the scope of use of such a broad-band resonance silencer, it is proposed that the pipe be designed as an insert which includes a central pipe section with two end-side pipe ends, that the insert be designed such that it can be inserted into the housing half-shells of the housing, and that the broad-band resonance silencer includes at least one acoustic channel.

A resonator includes: an inner pipe having first openings penetrated into an outer peripheral surface thereof from an inner peripheral surface thereof and second openings spaced apart from the first opening; a first cover adapted to allow a first resonant space to be formed between the outer peripheral surface of the inner pipe and the inner peripheral surface thereof, the first resonant space communicating with the internal space of the inner pipe through the first openings; and a second cover adapted to allow a second resonant space to be formed between the outer peripheral surface of the inner pipe and the inner peripheral surface thereof, the second resonant space communicating with the internal space of the inner pipe through the second openings.

A turbocharger includes an acoustic damper for attenuating noise from the compressor. The damper includes inner and outer duct walls defining an annular cavity therebetween, the outer duct being longer than the inner duct. An upstream wall bounds the annular cavity at the upstream end and defines an inlet aperture for fluid to pass through into the inner duct, and a downstream wall is axially spaced from the downstream end of the inner duct so as to define an expansion chamber fluidly connected to the annular cavity. The downstream wall defines an outlet aperture for the fluid. Partition walls between the two ducts partition the annular cavity into at least a first Helmholtz resonator and a first quarter-wave resonator that are axially serially arranged, and a second quarter-wave resonator that is circumferential serially arranged with respect to the first Helmholtz resonator.

A broad-band resonance silencer has an at least two-part housing which is designed to receive an exhaust-or gas-conveying pipe, which defines, with a circumferentially surrounding pipe jacket with acoustic openings formed therein, a pipe interior, wherein the pipe, in its installed position, is enclosed by a damping chamber formed by the housing, which chamber is actively connected to the pipe interior via the acoustic openings, and wherein the housing includes two axially split housing half-shells. In order to broaden the scope of use of such a broad-band resonance silencer, it is proposed that the pipe be designed as an insert which includes a central pipe section with two end-side pipe ends, that the insert be designed such that it can be inserted into the housing half-shells of the housing, and that the broad-band resonance silencer includes at least one acoustic channel.

The invention relates to a compressor, in particular a gas compressor, for instance for a turbocharger, for compressing a gaseous fluid, having a compressor housing (40) in which a compressor wheel (41) is rotatably arranged, wherein the compressor housing (40) has a gas intake manifold (43), via which gas can be fed to the compressor wheel (41), a compressor duct (42) being provided, via which the compressed gas can be discharged from the compressor wheel (41), an adjustment device (60) being arranged in the area of the gas intake manifold (43), wherein the adjustment device (60) has orifice elements (70), which can be adjusted linearly between a closed position and an open position, and by means of which the opening cross-section of the gas intake manifold (43) in a duct area can be varied in order to form a minimum opening cross-section (Ömin) in the closed position and a maximum opening cross-section (Ömax) in the open position, wherein in each case two adjacent orifice elements (70) have sealing segments (73.1, 76.1) which, in the closed position, face each other, in particular rest against each other. To be able to reduce the noise emissions in such a compressor in a simple and effective manner, provision is made according to the invention that the orifice elements (70) can be adjusted into a retracted operating position, in which body areas of the orifice elements (70) at least in some areas delimit a recess, in particular a circumferential groove, in the gas intake manifold (43) to form a resonator, in particular a Helmholtz resonator, and wherein provision may in particular be made that the orifice elements (70) can be adjusted, preferably continuously, between several retracted operating positions.

An air cleaner of an internal combustion engine is provided with a first housing including an inlet, a second housing including an outlet, and a filter element located between the first housing and the second housing. A Helmholtz resonator is arranged inside the first housing. An upright wall projects from a bottom wall of the first housing toward the filter element and extends in an axial direction of the inlet. The upright wall forms a chamber of the Helmholtz resonator. A noise-absorption region is defined by the upright wall, a side wall of the first housing, the bottom wall, and the filter element. The noise-absorption region leads to the inlet and extends in the axial direction.