Induction system duct with noise attenuating holes

Abstract

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.

1 . A duct for an induction system comprising:
 a wall providing a passage and having an effective length extending between an inlet and an outlet, the wall including an aperture at a location corresponding to an undesired pipe resonance, the passage in fluid communication with an outside environment through the aperture.   
   
   
       2 . The duct according to  claim 1 , comprising a porous non-woven structure overlapping the aperture. 
   
   
       3 . The duct according to  claim 2 , wherein the porous non-woven structure is foam. 
   
   
       4 . The duct according to  claim 2 , wherein the porous non-woven structure is arranged inside the pipe. 
   
   
       5 . The duct according to  claim 2 , wherein the porous non-woven structure is adhered to an exterior surface of the wall. 
   
   
       6 . The duct according to  claim 2 , wherein an adhesive is used to adhere the porous non-woven structure to the wall, the adhesive arranged adjacent to the aperture without significantly overlapping the aperture. 
   
   
       7 . The duct according to  claim 1 , wherein the aperture is provided by a cluster of holes in close proximity to one another. 
   
   
       8 . The duct according to  claim 1 , wherein the aperture is provided by multiple holes arranged about a circumference of the duct, the circumference at the location. 
   
   
       9 . The duct according to  claim 8 , wherein the holes are arranged on opposing sides to one another at the circumference. 
   
   
       10 . The duct according to  claim 1 , wherein multiple apertures are arranged along the effective length and configured to attenuate multiple undesired pipe resonances. 
   
   
       11 . The duct according to  claim 1 , wherein the location corresponds to a distance approximately one quarter the effective length from each of the inlet and outlet. 
   
   
       12 . The duct according to  claim 1 , wherein the location corresponds to a distance of approximately one half the effective length. 
   
   
       13 . The duct according to  claim 1 , wherein the aperture includes an area corresponding to a desired level of noise attenuation relating to the undesired pipe resonance. 
   
   
       14 . The duct according to  claim 1 , wherein the duct comprises first and second portions secured to one another to provide the passage.