Active acoustic attenuation mixing chamber
AssigneeNelson Industries, Inc.
InventorCary D. Bremigan
Life of this patent
Estimating the term…
Abstract
Active acoustic attenuation apparatus is provided for cancellation of noise from an exhaust pipe (12). A chamber (50) has an input (70) receiving exhaust from the exhaust pipe and directing the exhaust along a flowpath (76) to a chamber output (74). Speakers (88, 90) are transversely spaced and offset from the flowpath and introduce sound into the chamber at a space (56) having a transverse area at least as large as each speaker, to minimize acoustic loading of the speakers and to protect the speakers from the heat of hot exhaust for automotive applications, including electronic mufflers.
Claims34
Active acoustic attenuation apparatus for cancellation of noise from an exhaust pipe, comprising a chamber defined by an enclosing wall structure, said chamber having an input receiving exhaust from said pipe and directing said exhaust along a flowpath to a chamber output, said chamber having a section mounting an acoustic source directed along an axial centerline perpendicular to and offset from said flowpath, said acoustic source introducing sound into said chamber at a space having a transverse area at least as large as said acoustic source, to minimize acoustic loading of said acoustic source, the sound from said acoustic source cancelling undesirable noise in said exhaust.
Active acoustic attenuation apparatus for cancellation of noise from an exhaust pipe having a diameter substantially less than a cancelling acoustic source, comprising a chamber defined by an enclosing wall structure, said chamber having an input receiving exhaust from said pipe and directing said exhaust along a flowpath to a chamber output, said chamber having a section comprising an opening in a sidewall of said chamber, and having an axial centerline transversely offset from said flowpath, an acoustic source mounted to said chamber at said opening in said sidewall and extending externally of said chamber and introducing sound into said chamber at a space having an area at least as large as said acoustic source to minimize acoustic loading of said acoustic source, the sound from said acoustic source cancelling undesirable noise in said exhaust, said opening having a height transverse to said flowpath and a length parallel to said flowpath, said chamber having a height transverse to said flowpath and greater than or equal to the height of said opening in said sidewall, said chamber having a length parallel to said flowpath and greater than or equal to the length of said opening in said sidewall.
Active acoustic attenuation apparatus for cancellation of noise from an exhaust pipe of a given diameter, comprising a chamber defined by an enclosing wall structure, said chamber having an input opening of said given diameter and receiving said pipe and the exhaust therefrom and directing the exhaust along a flowpath to a chamber output, said chamber having a section transversely offset from said flowpath, said chamber having a width transverse to said flowpath and substantially comparable to said given diameter such that said chamber is not significantly wider than said exhaust pipe, an acoustic source mounted to said chamber at said section and introducing sound into said chamber to cancel undesirable noise in said exhaust, said acoustic source having a height transverse to said flowpath and a length parallel to said flowpath, said chamber having a height transverse to said flowpath and greater than or equal to the height of said acoustic source, said chamber having a length parallel to said flowpath and greater than or equal to the length of said acoustic source.
Active acoustic attenuation apparatus for cancellation of noise from an exhaust pipe, comprising a chamber defined by an enclosing wall structure, said chamber having an input receiving exhaust from said exhaust pipe and directing said exhaust along a flowpath to a chamber output, said chamber having a section transversely offset from said flowpath, an acoustic source mounted to said chamber at said section and having an axial centerline transversely offset from said flowpath and introducing sound into said chamber at a space having a transverse area at least as large as said acoustic source, to minimize acoustic loading to said acoustic source, the sound from said acoustic source cancelling undesirable noise in said exhaust, a tube within said chamber and extending from said chamber input below said axial centerline and stopping short of said chamber output, heat insulating material surrounding said tube within said chamber, said exhaust flowing along said flowpath through said tube.
Active acoustic attenuation apparatus for cancellation of noise from an exhaust pipe, comprising a chamber defined by an enclosing wall structure, said chamber having an input receiving exhaust from said exhaust pipe and directing said exhaust along a flowpath to a chamber output, said chamber having a section transversely offset from said flowpath, an acoustic source mounted to said chamber at said section and having an axial centerline transversely offset from said flowpath, and introducing sound into said chamber at a space having a transverse area at least as large as said acoustic source, to minimize acoustic loading of said acoustic source, the sound from said acoustic source cancelling undesirable noise in said exhaust, an inner tube within said chamber and extending from said chamber input below said axial centerline and stopping short of said chamber output, said exhaust flowing along said flowpath through said inner tube, an outer tube concentric to said inner tube and defining a space between said inner tube and said outer tube and extending from said chamber input and having an air inlet at said chamber input for receiving air into the space between said inner and outer tubes for convective cooling of said inner tube.
Active acoustic attenuation apparatus for cancellation of noise from an exhaust pipe, comprising a mixing chamber having left and right sidewalls facing each other across a space, each sidewall having an upper generally semicircular portion and a lower generally rectangular portion, said mixing chamber having front, rear, top and bottom walls extending transversely between said sidewalls and enclosing said space, said front wall having a bottom, said front wall having an opening therein at the bottom thereof adjacent said bottom wall and providing a chamber input receiving said exhaust pipe, said rear wall having a bottom, said rear wall having an opening therein at the bottom thereof adjacent said bottom wall and providing a chamber output, such that exhaust flows along a path through said chamber along said bottom wall from said opening in said front wall at said chamber input to said opening in said rear wall at said chamber output, at least one of said sidewalls of said chamber having a circular opening therein, said circular opening having an upper portion and a lower portion, the upper portion of said circular opening being in said upper semicircular portion of said sidewall, the lower portion of said circular opening being in the lower generally rectangular portion of said sidewall, said opening in said front wall and said opening in said rear wall defining a flowpath therebetween, said circular opening having an axial centerline transversely offset from said flowpath, said flowpath being below the axial centerline of said circular opening in said sidewall, an acoustic source mounted to said chamber at said circular opening in said sidewall and introducing sound into said chamber in said space to cancel undesirable noise in said exhaust.
Active acoustic attenuation apparatus for cancellation of noise from a hot exhaust pipe, including the exhaust pipe of a motor vehicle, comprising a chamber defined by an enclosing wall structure, said chamber having an input receiving hot exhaust from said hot exhaust pipe and directing said hot exhaust along a flowpath to a chamber output, said chamber having a section mounting an acoustic source directed along an axial centerline transversely spaced and offset from said flowpath, to protect said acoustic source from said hot exhaust, and introducing sound into said chamber at a space having a transverse area at least as large as said acoustic source, to minimize acoustic loading of said acoustic source, the sound from said acoustic source cancelling undesirable noise in said hot exhaust.
Dependencies are inferred from the claim text.