Louver flow muffler

• US 4,111,279 A
• Filed: 07/26/1976
• Issued: 09/05/1978
• Est. Priority Date: 07/26/1976
• Status: Expired due to Term

• Current Assignee: Tenneco Incorporated (Apollo Global Management, Inc.)
• Original Assignee: Tenneco Incorporated (Apollo Global Management, Inc.)
• Inventors: Sterrett, Dale E.
• Primary Examiner(s): Hix, L. T.
• Assistant Examiner(s): Fuller, Benjamin R.
• Application Number:
  US05/708,513
• Time in Patent Office: 771 Days
• Field of Search: 181/57, 181/56, 181/59, 181/53, 181/48, 181/61, 181/63, 181/250, 181/266, 181/276, 181/249, 181/264, 181/265, 181/268, 181/269, 181/272-275
• US Class Current: 181/264
• CPC Class Codes: F01N 1/02 by using resonance
• CPC Class Codes: F01N 2490/155 being disposed one after the other in flow direction

Abstract

A muffler for lowering the exhaust gas noise level of combustion engines has a Helmholtz resonator chamber and a single straight tube member that is provided with a perforated portion outside said chamber large enough for full flow through it of all gas flowing through the muffler, one end of the tube extending into the resonator chamber and the tube diameter, chamber volume, and length of the tube between said one end and said perforated portion being related to and dependent upon each other in accordance with the Helmholtz formula so that the resulting Helmholtz system attenuates a predetermined frequency when the muffler is placed in an exhaust system at or near the pressure antinode of that frequency.

Claims

1. In a muffler for reducing the noise level of combustion engine exhaust gases and for attenuating a preselected low frequency sound, the combination of a housing having port means forming an inlet and port means forming an outlet for gas flowing through the muffler, substantially imperforate partition means forming a resonator chamber in the housing, said housing having a gas flow space outside said resonator chamber, a single gas flow tube member with a wall and open at both ends and having one end portion connected to a port means and the other end portion extending into and opening into said resonator chamber and supported on said partition means. said gas flow tube member having an intermediate portion between said end portions and located outside of said chamber and said intermediate portion being in the path of gas flowing between the inlet and the outlet and said intermediate portion including a gas flow through section in said space containing a multiplicity of small area sound attenuating perforations in said wall having a total open area substantially equal to the cross sectional area of that section of the tube member and providing passage for substantially all the gas flowing through the muffler to flow between the inside and the outside of the tube member through said wall at said section, the length of the tube member between the end thereof in said resonator chamber and the adjacent end of said perforated section as well as the inside diameter of said tube member throughout said length and the volume of said resonator chamber all being interrelated and interdependent in accordance with the Helmholtz formula whereby they serve to form a Helmholtz system to attenuate said preselected low frequency, and a gas flow conduit open at both ends and supported on said partition means and extending through said resonator chamber and having one end portion connected to the other of said port means and the other end portion opening into said gas flow space whereby gas may flow between it and said perforations.

2. A muffler as set forth in claim 1 wherein said wall forming said end portion of the tube member that extends into said resonator chamber is imperforate.

3. A muffler as set forth in claim 1 wherein said wall forming said end portion of the tube member that extends into said resonator chamber has a multiplicity of spaced openings formed through it and defining a circumferential ring around the tube member, said ring being spaced a substantial distance away from the end of the tube member but inside the resonator chamber and serving to raise the frequency attenuated by the Helmholtz system above that determined by the Helmholtz formula.

4. In a muffler for reducing the noise level of combustion engine exhaust gases and for attenuating a preselected low frequency sound, the combination of a housing having inlet means and outlet means for gas flowing through the muffler, substantially imperforate partition means forming a resonator chamber in the housing, a single gas flow tube member open at both ends and having an end portion extending into and opening into said resonator chamber and supported on said partition means, said gas flow tube member having another portion located outside of said resonator chamber and said portion being in the path of gas flowing between the inlet means and outlet means and said portion including a section containing a multiplicity of small area sound attenuating perforations having a total open area substantially equal to the cross sectional area of that section of the tube member and providing for full gas flow between the inside and the outside of the tube member, the length of the tube member between the end thereof in said chamber and the adjacent end of said perforated section as well as the inside diameter of said tube member throughout said length and the volume of said resonator chamber all being interrelated and interdependent in accordance with the Helmholtz formula whereby they serve to form a Helmholtz system to attenuate said preselected low frequency, the wall of said end portion of the tube member that extends into said resonator chamber having a multiplicity of spaced openings formed through the wall thereof and defining a circumferential ring around the tube member, said ring being spaced a substantial distance away from the end of the tube member and serving to raise the frequency attenuated by the Helmholtz system above that determined by the Helmholtz formula.

5. In a muffler for reducing the noise level of combustion engine exhaust gases and for attenuating a preselected low frequency sound, the combination of a housing having inlet means and outlet means for gas flowing through the muffler, substantially imperforate partition means forming a resonator chamber in the housing, an inlet conduit connected to said inlet means to receive all gas flowing into the muffler, said conduit including a gas flow tube member having an open end portion extending into and opening into said resonator chamber, said tube being supported on said partition means, said housing having a gas flow space outside said resonator chamber and said gas flow tube member having an intermediate portion located in said space and said intermediate portion including a section containing a multiplicity of small area louvers having a total open area substantially equal to the cross sectional area of that section of the tube member and providing passage for subsantially all the gas flowing into said conduit to flow from the inside to the outside of the tube member through said louvers into said space, the length of the tube member between the end thereof in said resonator chamber and the adjacent end of said louvered section as well as the inside diameter of said tube member throughout said length and the volume of said resonator chamber all being interrelated and interdependent in accordance with the Helmholtz formula whereby they serve to form a Helmholtz system to attenuate said preselected low frequency, and an outlet conduit connected to said outlet means to receive all gas flowing through said muffler, said conduit being supported on said partition means and extending through said resonator chamber and having an inlet in said gas flow space.

6. In a muffler for reducing the noise level of combustion engine exhaust gases and for attenuating a preselected low frequency sound, the combination of a housing having inlet means and outlet means for gas flowing through the muffler, substantially imperforate partition means forming a resonator chamber in the housing, an outlet conduit connected to said outlet means to conduct all gas flowing through the muffler, said conduit including a gas flow tube member having an open end portion extending into and opening into said reasonator chamber, said tube being supported on said partition means, said housing having a gas flow space outside said resonator chamber and said gas flow tube member having an intermediate portion located in said space, an inlet conduit connected to said inlet means to receive all gas flowing into the muffler and extending through said resonator chamber and having an outlet in said gas flow space, the intermediate portion of said tube including a section containing a multiplicity of small area louvers having a total open area substantially equal to the cross sectional area of that section of the tube member and providing passage for substantially all the gas flowing into said space to flow from the outside to the inside of said tube member through said louvers, the length of the tube member between the end thereof in said resonator chamber and the adjacent end of said louvered section as well as the inside diameter of said tube member throughout said length and the volume of said resonator chamber all being interrelated and interdependent in accordance with the Helmholtz formula whereby they serve to form a Helmholtz system to attenuate said preselected low frequency.

7. An acoustic muffler for use in exhaust systems or combustion engines to provide sound attenuation in the medium and high frequency range of about 700-4000 Hz and in the low frequency range of about 40-700 Hz comprising an elongated housing defining an internal cavity and having a longitudinal axis, said housing having an inlet for gas at one end and an outlet for gas at the other end, transverse partition means in said housing extending transversely to said axis across the width of the housing and subdividing said cavity into a resonator chamber and a gas flow space, a tubular inlet conduit joined to said inlet to carry substantially all gas flowing into the muffler, a tubular outlet conduit joined to said outlet to carry substantially all gas flowing out of the muffler, said conduits being supported on the partition means and extending lengthwise of said housing and substantially parallel to said axis and being longitudinally overlapping and transversely separated, one of said conduits having an end portion opening into said resonator chamber and an intermediate portion located in said gas flow space, said intermediate portion including a section containing a multiplicity of small area louvers having a total open area substantially equal to the cross sectional area of that section of the conduit and providing a passage for substantially all the gas flowing through the muffler to flow between the inside and the outside of the conduit through said louvers, the length of the one conduit betweeen the end thereof in said resonator chamber and the adjacent end of said louvered section as well as the inside diameter of said conduit throughout said length and the volume of said resonator chamber all being interrelated and interdependent in accordance with the Helmholtz formula to form a Helmholtz system to substantially attenuate a preselected low frequency in said range of about 40-700 Hz, the other of said conduits extending through said resonator chamber and opening said gas flow space, said gas flow space providing a longitudinal and transverse path for gas to flow from the inlet conduit to the outlet conduit and acting in combination with said louvers and said conduits to provide substantial sound attenuation in the range of about 700-4000 Hz.

8. A muffler as set forth in claim 7 wherein the one of said conduits having the louvers therein is the inlet conduit and said louvers providing an outlet for substantially all gas flowing through the conduit to enter said gas flow space.

9. A muffler as set forth in claim 7 wherein the one of said conduits having the louvers therein is the outlet conduit and said louvers providing an inlet for substantially all gas flowing through the gas flow space to enter said outlet conduit.