Abstract: The invention relates to a Helmholtz resonator (6) for damping airborne sound in a space, particularly in a conduit (4, 5) transporting airborne sound, comprising a housing (8) surrounding a resonance volume (9), comprising at least one neck (10) for connecting the resonance volume (9) to the space or to the conduit (4, 5) transporting the airborne sound. The Helmholtz resonator (6) obtains at least two resonance frequencies if the housing (8) has at least one wall section delimiting the resonance volume (9), said wall section being formed by a vibratory membrane (11), and if the membrane (11) is tuned such that the resonance frequency thereof corresponds to the first order of the resonance frequency of an identically constructed Helmholtz resonator that does not have such a membrane (11).

Abstract: An air induction silencer assembly includes an acoustic interference member disposed within a conduit. The acoustic interference member is tuned to acoustically cancel a selected noise energy frequency. An acoustic absorbing member is also disposed within the conduit. The acoustic absorbing member converts noise energy within the conduit into heat energy to attenuate noise energy within the air induction silencer assembly. The air induction silencer assembly connects to a flexible conduit that includes an inlet portion, an outlet portion, and a flexible joint that connects the inlet portion and the outlet portion together. The flexible joint includes a rolling lobe and a rolling surface. The rolling lobe moves along the rolling surface when the inlet portion moves relative to the outlet portion.

Abstract: An induction system is designed for an engine that includes a manifold having a plenum in fluid communication with primary runners. A plenum valve is arranged between first and second chambers of the plenum that are respectively in fluid communication with first and second sets of the primary runners. The plenum valve is configured to move between open and closed positions to regulate flow between the first and second chambers. A secondary runner is arranged upstream from and in fluid communication with the plenum. The secondary runner includes first and second runner portions with the second runner portion being shorter than the first runner portion. A runner valve is arranged in the secondary runner between the first and second runner portions and is configured to selectively direct flow through the first and second runner portions to the plenum to obtain a desired effective tuning length.

Abstract: A noise attenuation system (10) for an air induction system (12) includes an air inlet duct (16) having an open end (18) to draw in air and a loudspeaker (22) mounted within the inlet duct (16) and facing the open end (18) of the inlet duct (16). The air horn (24) is connected to the loudspeaker (22) to tune the sound output and increase the sound power from the loudspeaker (22) to optimize cancellation of noise generated by the air induction system (16) at lower frequencies. An open end (18) of the air horn (24) is positioned within a plane defined by the open end (18) of the air inlet duct (16). A microphone (26) is positioned near the air inlet duct (16) and is in communication with a controller (28). The controller (28) generates an input to the loudspeaker (22). The input to the loudspeaker (22) is out of phase with the noise detected by the microphones (26) to cancel a portion of noise emitted from the open end (18) of the air inlet (16).

Abstract: A noise attenuation system (10) for an air induction system (12) includes an air inlet duct (16) having an open end (18) to draw in air and a loudspeaker (22) mounted within the inlet duct (16) and facing the open end (18) of the inlet duct (16). The air horn (24) is connected to the loudspeaker (22) to tune the sound output and increase the sound power from the loudspeaker (22) to optimize cancellation of noise generated by the air induction system (16) at lower frequencies. An open end (18) of the air horn (24) is positioned within a plane defined by the open end (18) of the air inlet duct (16). A microphone (26) is positioned near the air inlet duct (16) and is in communication with a controller (28). The controller (28) generates an input to the loudspeaker (22). The input to the loudspeaker (22) is out of phase with the noise detected by the microphones (26) to cancel a portion of noise emitted from the open end (18) of the air inlet (16).