This application relates to an induction system duct that incorporates noise attenuation features.
Typically, vehicle engine induction systems utilize several noise attenuation devices to attenuate undesired resonances within the induction system. It is sometimes difficult to incorporate the noise attenuation devices into an induction system due to limited packaging space, cost and complexity.
An induction system typically includes a duct having a pipe resonance associated with its effective length. Often these resonances are undesirable from an overall noise level and sound quality perspective. Typically, a Helmholtz resonator is added to the duct and tuned such that the undesired standing wave within the duct is attenuated. In particular, the volume of the “bottle” and size of the “neck” of the Helmholtz resonator is sized to attenuate a particular frequency in the induction system.
Packaging the Helmholtz resonator within the engine compartment can be difficult. Furthermore, the Helmholtz resonator is typically sized for the particular engine application. As a result, a greater number of parts are needed for a vehicle due to the variety of engines typically made available for vehicles.
What is needed is a noise attenuation device for a duct that is easy to package and that is versatile so that it may be used for different engines.
A duct for an induction system is provided that has an effective length between an inlet and outlet. An aperture is provided a wall of the duct at a location corresponding to a pipe resonance for attenuating noise at the pipe resonance frequency. In one example, the aperture is provided using a cluster of holes arranged at the location. Multiple apertures are arranged about a circumference of the duct, for example, at opposing sides of the duct. In one example, an aperture is provided at a distance of approximately one quarter the effective length from both the inlet and the outlet. A porous non-woven structure is arranged over the aperture to minimize pressure losses associated with the aperture.
Accordingly, the example duct with noise attenuating apertures requires no significant additional packaging space and may be modified to suit a particular engine application.
These and other features of the application can be best understood from the following specification and drawings, the following of which is a brief description.
An induction system 10 is schematically shown in
In one example embodiment, the wall 24 of the duct 16 includes an aperture 26 arranged at a location 28 corresponding to a standing wave producing undesired noise. The aperture 26 permits air to flow between the outside environment and the passage 22 to attenuate the noise associated with the standing wave. In one example, a porous non-woven structure, such as an open-cell foam 30, overlaps the aperture 26 to minimize pressure losses attributable to the aperture 26.
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In the example shown, the duct 16 is provided by securing first and second portions 48, 50 to one another at complimentary flanges 52. In one example, the duct 16 is constructed from plastic and secured, for example, by adhesive or welding. A seal 54 is provided on the first portion 48 at the outlet 20 to provide a seal between the duct 16 and an intake manifold, for example.
Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.