Patent Publication Number: US-7219764-B1

Title: Exhaust muffler

Description:
BACKGROUND OF THE INVENTION 
   This invention relates generally to mufflers and more particularly to sound attenuating exhaust mufflers for internal combustion engines. 
   Sound attenuating mufflers exist in the art, and as such their structure and function are well known. U.S. Pat. No. 4,574,914, U.S. Pat. No. 6,089,347, U.S. Pat. No. 6,286,623 and U.S. Pat. No. 6,341,664 disclose various muffler designs, the entire contents of which are incorporated herein by reference in their entireties. 
   While it is important for a muffler to attenuate engine noise, it is also desirable for a muffler to have sonic characteristics that are pleasing to the ear throughout the engine speed range. Desirable acoustics can range from a low RPM rumble to a crisp and aggressive high RPM exhaust note. 
   Muffler design also affects engine power output. A muffler preferably allows for a high exhaust flow rate. 
   There remains a need for novel muffler designs capable of producing desirable sound characteristics throughout the engine speed range while also providing sufficient noise attenuation and allowing sufficient flow and power characteristics. There remains a need for muffler designs that allow for a high flow rate with minimal drone at cruising speeds. There also remains a need for muffler designs having said functional characteristics that are less labor intensive and less expensive to manufacture than traditional designs. 
   All US patents and applications and all other published documents mentioned anywhere in this application are incorporated herein by reference in their entirety. 
   Without limiting the scope of the invention a brief summary of some of the claimed embodiments of the invention is set forth below. Additional details of the summarized embodiments of the invention and/or additional embodiments of the invention may be found in the Detailed Description of the Invention below. 
   A brief abstract of the technical disclosure in the specification is provided as well only for the purposes of complying with 37 C.F.R. 1.72. The abstract is not intended to be used for interpreting the scope of the claims. 
   BRIEF SUMMARY OF THE INVENTION 
   In at least one embodiment, the invention is directed to a muffler comprising a casing having an internal volume, an inlet and an outlet, and a diverter plate dividing the internal volume into a first chamber and a second chamber. The diverter plate comprises a baffle wall portion and a diverter having a deflecting surface oriented at an angle to the baffle wall portion. The baffle wall includes at least one aperture allowing fluid communication between the first chamber and the second chamber. Exhaust gasses flowing through the muffler may pass through the aperture and be deflected against the deflecting surface of the diverter. 
   In at least one other embodiment, a diverter plate includes a first aperture, a second aperture, a first diverter and a second diverter. The shape of the first aperture may comprise a mirror image of the shape of the second aperture. The shape of the first diverter may comprise a mirror image of the shape of the second diverter. 
   A diverter plate may further comprise a connecting member connected between the first diverter and the second diverter. 
   In at least one other embodiment, a muffler comprises a casing having an internal volume, an inlet, an outlet and a diverter plate. The diverter plate divides the internal volume into a first chamber and a second chamber, the first chamber having the inlet and the second chamber having the outlet. The diverter plate comprises a first diverter, a second diverter and a baffle wall portion having at least one aperture. The first diverter and the second diverter are oriented at equal but opposite angles with respect to the baffle wall portion. The first diverter and the second diverter extend into the second chamber. The at least one aperture allows fluid communication between the first chamber and the second chamber. 
   In at least one other embodiment, the invention is directed to a method of making a muffler comprising: providing a casing having an internal volume; providing a diverter plate; orienting the diverter plate within the internal volume of the casing; and securing the diverter plate to the casing. The diverter plate may comprise a baffle wall portion and a diverter having a deflecting surface oriented at an angle to the baffle wall portion. 
   In some embodiments, the step of providing a diverter plate further comprises providing a sheet of material and stamping the sheet to form the baffle wall portion, the aperture and the diverter. 
   These and other embodiments which characterize the invention are pointed out with particularity in the claims annexed hereto and forming a part hereof. However, for a better understanding of the invention, its advantages and objectives obtained by its use, reference can be made to the drawings which form a further part hereof and the accompanying descriptive matter, in which there are illustrated and described various embodiments of the invention. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A detailed description of the invention is hereafter described with specific reference being made to the drawings. 
       FIG. 1  shows an embodiment of a muffler. 
       FIG. 2  shows a sectional view of the muffler of  FIG. 1  taken across line  2 — 2  of  FIG. 1   
       FIG. 3  shows an exploded view of an embodiment of a diverter plate. 
       FIGS. 4 and 5  show further views of an embodiment of a diverter plate. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   While this invention may be embodied in many different forms, there are described in detail herein specific embodiments of the invention. This description is an exemplification of the principles of the invention and is not intended to limit the invention to the particular embodiments illustrated. 
   For the purposes of this disclosure, like reference numerals in the figures shall refer to like features unless otherwise indicated. 
     FIGS. 1 and 2  show an embodiment of a muffler  10  comprising a casing  12 , at least one inlet  14 , at least one outlet  16  and a diverter plate  30 . Exhaust gasses may enter through the inlet  14 , pass through the muffler  10  and exit through the outlet(s)  16 . 
   The casing  12  may have any suitable cross-sectional shape and in various embodiments may have a rectangular, circular or oval cross-sectional shape. The casing  12  may define an outer shape of the muffler  10 , and a central longitudinal axis  11  of the casing  12  may comprise a central longitudinal axis  11  of the muffler  10 . 
   The casing  12  may comprise a wall  20  that defines an internal volume. The wall  20  may have an inner surface  22  and an outer surface  21 . In some embodiments, the wall  20  may comprise a single layer of material. In some embodiments, the wall  20  may comprise multiple layers of material, for example a first layer and a second layer oriented coaxially, or a continuous sheet of material wrapped spirally such that any portion of the wall  20  comprises at least two layers of material. 
   The casing  12  may further comprise a first end plate  24  and a second end plate  26 . The first end plate  24  may house the inlet  14  and the second end plate  26  may house the outlet(s)  16 . The end plates  24 ,  26  may be fixedly attached to an edge  23  of the wall  20 , for example by welding. 
   The diverter plate  30  may comprise a baffle wall portion  36  and may separate the internal volume of the casing  12  into a first chamber  46  and a second chamber  48 . In some embodiments, the diverter plate  30  may be positioned approximately halfway between the first end plate  24  and the second end plate  26 . An outer perimeter  31  of the diverter plate  30  may be shaped similarly to the cross-sectional shape of the casing  12  and may abut the inner surface  22  of the casing  12 . The diverter plate  30  may be fixedly attached to the casing  12  using any suitable method, for example by welding. 
   In some embodiments, the diverter plate  30  may have a flange  32  which may add structural integrity, aid in positioning the diverter plate  30  within the casing  12  and provide an attachment surface. A flange  32  may have any suitable size, shape and orientation, and preferably has an outer surface  33  oriented orthogonally to the baffle wall  36 . 
   The baffle wall portion  36  may have any suitable shape and preferably comprises a planar surface. The baffle wall  36  may have any suitable orientation within the casing  12  and is preferably oriented orthogonally to the longitudinal axis  11 . 
   The diverter plate  30  may have at least one aperture  40 , and in some embodiments may have multiple apertures  40 , such as a first aperture  40  and a second aperture  42 . The aperture(s)  40  allow fluid communication between the first chamber  46  and the second chamber  48 . 
     FIG. 3  shows an exploded view of an embodiment of a diverter plate  30 , and  FIG. 4  shows another view of an embodiment of a diverter plate  30 . Each aperture  40  may have any suitable shape and may be formed in the diverter plate  30  using any suitable method. In some embodiments, an aperture  40  may comprise a D-shape, having a straight portion  70  and a curved portion  72 . The straight portion  70  may be oriented vertically. The curved portion  72  may be oriented outwardly from the straight portion  70  with respect to the longitudinal axis  11  of the muffler  10 . In some embodiments, the curvature of the curved portion  72  may be similar to the curvature of the inner surface  22  of the casing  12 . 
   In some embodiments, a first aperture  40  and a second aperture  42  may have a similar shape. In some embodiments, the shape of a first aperture  40  may comprise a mirror image of the shape of a second aperture  42 . The mirror image may be taken across any suitable axis, such as a vertical axis  71  that may intersect the longitudinal axis  11  of the muffler  10 . 
   In various embodiments, the total area of the aperture(s)  40  may comprise any suitable percentage of the total cross-sectional area of the diverter plate  30  or of the cross-sectional area of the casing  12 . In some embodiments, the total area of the aperture(s)  40  may comprise 20–60% of the cross-sectional area of the casing  12 . In some embodiments, the total area of the aperture(s)  40  may comprise 30–40% of the cross-sectional area of the casing  12 . 
   In some embodiments, the total area of the aperture(s)  40  may be equal to or greater than the cross-sectional area of the inlet  14  of the muffler  10 . 
   The diverter plate  30  further comprises at least one diverter  50 . A diverter  50  may have any suitable size and shape, and may have any suitable orientation within the muffler  10 . In some embodiments, a diverter  50  is attached to the baffle wall portion  36  at one end and extends into the second chamber  48  (see  FIG. 2 ). In some embodiments, multiple diverters  50  may be provided, for example, one diverter  50  for each aperture  40 . Each diverter  50  may comprise a deflecting surface  56  that is oriented at an angle to the baffle wall portion  36 . In some embodiments, the deflecting surface  56  may comprise a planar surface. Exhaust gasses flowing through the muffler  10  may pass through an aperture  40  and be deflected by a diverter  50 . 
   A diverter  50  may be located immediately adjacent to an aperture  40 . In some embodiments, the shape of a diverter  50  may be similar to the shape of an aperture  40 , for example comprising a D-shape, having a straight portion  51  and a curved portion  54 . The straight portion  51  may be aligned with a straight portion  70  of a D-shaped aperture  40 . A curved portion  54  helps exhaust gasses to flow around the diverter  50  and reduce turbulence. 
   In some embodiments, a diverter  50  may be made from a separate piece of material and attached to the baffle wall  36  or any other portion of the diverter plate  30  using any suitable method, such as welding, crimping, swaging, etc. In some embodiments, an edge portion of a diverter  50  may abut and/or be attached to an edge portion of the baffle wall  36  that defines an aperture  40 . 
   In some embodiments, a diverter  50  and the baffle wall  36  may be formed from a single, continuous piece of material. For example, a single piece of material may be stamped to form one or more diverters  50  and a baffle wall  36  having one or more apertures  40 . Thus, in some embodiments, material removed from the baffle wall  36  to form an aperture  40  may be used to form a diverter  50 . 
   Preferably, the diverter(s)  50  are “suspended” with respect to the casing  12 , wherein no portion of the diverter  50  directly contacts the casing  12 . In some embodiments, each diverter  50  may be supported only by a connected edge where the diverter  50  attaches to the baffle wall  36  of the diverter plate  30 . The suspended diverter(s)  50  reduce the amount of drone and noise experienced outside of the muffler, as much of the vibration experienced by a diverter  50  is not directly imparted to the casing  12 . 
     FIG. 2  shows a sectional top view of an embodiment of the muffler  10 . Exhaust gasses flowing through the muffler  10  may pass through the first chamber  46 , through an aperture  40  and be deflected by the deflecting surface  56  of a diverter  50 . The deflection of exhaust gasses creates a high pressure zone  60  in the area of the deflected gasses to one side of the diverter  50  and a low pressure zone  62  in the area behind the diverter  50 . 
   In some embodiments, the diverter(s)  50  are oriented such that deflected exhaust gasses are directed outward, i.e. away from the central axis  11  (see  FIG. 1 ) of the muffler  10 . In other embodiments, the diverter(s)  50  may be oriented to direct exhaust gasses in any suitable direction. 
   The deflecting surface  56  of a diverter  50  may be oriented at any suitable angle α with respect to the baffle wall  36 . In some embodiments, the angle α may range from 10 to 80 degrees. In some preferred embodiments, the angle α may range from 20 to 50 degrees. In some preferred embodiments, the angle α may range from 25 to 35 degrees. 
   In some embodiments, the diverter plate  30  may comprise a first diverter  50  and a second diverter  52 . The first diverter  50  may be adjacent to the first aperture  40 , and the second diverter  52  may be adjacent to the second aperture  42 . The first diverter  50  and the second diverter  52  may comprise a similar shape. In some embodiments, the shape of a first diverter  50  may comprise a mirror image of the shape of a second diverter  52 . The mirror image may be taken across any suitable axis, such as a vertical axis  71  (see  FIG. 3 ). 
   In preferred embodiments, the deflecting surface  56  of a first diverter  50  and the deflecting surface  56  of a second diverter  52  may be oriented at equal but opposite angles α with respect to the baffle wall  36 . Thus, the deflecting surface  56  of the first diverter  50  and the deflecting surface  56  of the second diverter  52  may be symmetrical across the longitudinal axis  11 , and may be oriented at equal but opposite angles with respect to the longitudinal axis  11 . In other embodiments, a first diverter  50  and a second diverter  52  may comprise different shapes, may be oriented at different angles α, and/or may otherwise be asymmetrical across the longitudinal axis  11 . 
   The diverter plate  30  may comprise any material suitable to withstand the high temperatures encountered during operation. The diverter plate  30  preferably comprises a metal such as steel. In various embodiments, diverter(s)  50  may comprise the same material as other portions of the diverter plate  30 , or may comprise one or more different materials. 
   Referring to  FIGS. 3–5 , in some embodiments, a diverter plate  30  may further comprise a connecting member  78 . In some embodiments, a diverter plate  30  may further comprise a splitter plate  86 . 
   A connecting member  78  may comprise a reinforcing structural connection between a first diverter  50  and a second diverter  52 . A connecting member  78  may have any suitable cross-sectional shape. The connecting member  78  adds rigidity to the diverter plate  30  and transfers vibrations between a first diverter  50  and a second diverter  52 , thereby damping ringing or tuning fork oscillations in the diverters  50 ,  52 . The connecting member  78  allows cancellation of soundwaves and vibrations in the diverters  50 ,  52  without requiring the diverters  50 ,  52  to be attached to the casing  12 . The connecting member  78  also helps to provide symmetry across the longitudinal axis  11  during operation and may help to ensure that exhaust flow is equally divided between a first aperture  40  and a second aperture  42 . 
   The connecting member  78  may be attached to a first diverter  50  and a second diverter  52  using any suitable method, and is preferably fixedly attached, for example by welding. A connecting member  78  may be attached to any suitable location on the diverters  50 ,  52 . Desirably, the connecting member  78  connects to similar locations on each diverter  50 ,  52  (i.e. symmetrical across the longitudinal axis  11 ). In some embodiments, a connecting member  78  connects to outward locations on the diverters  50 ,  52 , for example connecting to a portion of each diverter  50 ,  52  that is opposite or spaced away from the portion of each diverter  50 ,  52  that is connected to the baffle wall portion  36 . 
   In some embodiments, the connecting member  78  may comprise a first connecting portion  80 , an elongate portion  81  and a second connecting portion  82 . The elongate portion  81  may span between the first connecting portion  80  and the second connecting portion  82 . 
   In some embodiments, the elongate portion  81  may be oriented parallel to the baffle wall  36 . The first connecting portion  80  may comprise an attachment surface  79  that is parallel to the first diverter  50 , and the second connecting portion  82  may comprise an attachment surface  79  that is parallel to the second diverter  52 . Each attachment surface  79  may abut and be attached to a diverter  50 ,  52 . Each attachment surface  79  may be attached to a surface of a diverter  50 ,  52  that is oriented opposite the deflecting surface  56 . 
   A splitter plate  86  may help to divide the flow of exhaust gasses between a first aperture  40  and a second aperture  42 . The splitter plate  86  may further help to prevent exhaust gasses passing through the first chamber  46  from being reflected back toward the inlet  14 . A central portion  37  of the baffle wall  36  may be oriented between the first aperture  40  and the second aperture  42 . In some embodiments, the central portion  37  may be oriented such that exhaust gasses that flow into the central portion  37  may be reflected back toward the inlet  14 . The splitter plate  86  may comprise an extension of the deflecting surfaces  56  of the diverters  50 ,  52 , and may be positioned substantially between the inlet  14  and the central portion  37  of the baffle wall  36 . 
   In some embodiments, a splitter plate  86  may comprise a first portion  90  and a second portion  92 . The first portion  90  may be oriented at an angle to the second portion  92 . A central portion of the splitter plate  86  may comprise a bend  91 . The first portion  90  may comprise a substantially planar surface that is oriented parallel to the deflecting surface  56  of the first diverter  50 . The second portion  92  may comprise a substantially planar surface that is oriented parallel to the deflecting surface  56  of the second diverter  52 . The first portion  90  may be fixedly attached to the first diverter  50  and the second portion  92  may be fixedly attached to the second diverter  52 , for example by welding. The splitter plate  86  may be positioned such that the central portion  91  is aligned with the central longitudinal axis  11  of the muffler  10 . 
   A splitter plate  86  may be particularly desirable when a width dimension W of the central portion  37  of the baffle wall  36  is equal to or greater than one inch. 
   In some embodiments, a splitter plate  86  may comprise a plurality of apertures  88 , for example oriented in a pattern as depicted in the Figures. In some embodiments, a plurality of apertures  88  oriented in a line may help to form a bend  91 . 
   In an alternative embodiment (not shown), rather than using a splitter plate  86  having a first portion  90  and a second portion  92  as described herein, individual extension pieces may be used to extend the deflecting surface  56  of each deflector  50 . 
   Referring again to  FIGS. 1 and 2 , in some embodiments, a muffler  10  may further comprise one or more baffle plates  64 . A baffle plate  64  may comprise a baffle wall  66  and at least one fluid passageway  68 . Each baffle plate  64  may be oriented within the casing  12  and may divide the internal volume of the casing  12  to define an additional chamber  74 . As shown in  FIG. 2 , the baffle plates  64  are positioned such that the first chamber  46  and the second chamber  48  each comprise approximately 30% of the internal volume of the casing  12 . Each additional chamber  74  comprises approximately 20% of the internal volume of the casing  12 . 
   In some embodiments, a baffle plate  64  may comprise a flange, for example being similar to the flange  32  of a diverter plate  30 . In some embodiments, the baffle wall  66  of a baffle plate  64  may be oriented orthogonally to the longitudinal axis  11  of the muffler  10 . In some embodiments, the fluid passageway  68  may comprise a shaped or radiused end portion  76  which may reduce turbulence in the flowing exhaust gasses. 
   The number of baffle plates  64  used in the muffler  10 , the location of each baffle plate  64 , the number of fluid passageways  68  and the area of each fluid passageway  68  may be adjusted in order to tune the sound characteristics of the muffler  10 . In some embodiments, a baffle plate  64  may be positioned with a fluid passageway  68  directly adjacent to the low pressure zone  62  created by the diverter plate  30 . 
   In some alternative embodiments, a diverter  50  and/or the deflecting surface  56  of a diverter may include curvature. Curvature may be about any suitable axis, such as a vertical axis. The curvature of a deflector  50  may be convex or concave, for example deflecting exhaust gasses in convergent directions or in divergent directions. 
   In some alternative embodiments, diverters  50  and apertures  40  may have other shapes and/or orientations. For example, a diverter  50  may have a straight portion  51  that is oriented horizontally. A second diverter may comprise a mirror image of a first diverter, wherein the mirror image is taken across a horizontal axis. A diverter  50  may have a straight portion  51  that is located farther away from the longitudinal axis  11  of the muffler  10  than any other portion of the diverter  50 . Various apertures  40  used with such alternative embodiments may be shaped accordingly. 
   In some embodiments (not shown), the baffle wall  36  may have a bend or may otherwise comprise a first baffle wall portion oriented at an angle to a second baffle wall portion. The first baffle wall portion may be oriented at an angle to the longitudinal axis  11  of the casing  12 , while the second baffle wall portion may be oriented at an equal but opposite angle to the longitudinal axis  11 . 
   The invention is further directed to methods of making a muffler  10  having a diverter plate  30 . A method may include the steps of providing a casing  12  having an internal volume, providing a diverter plate  30 , orienting the diverter plate within the internal volume of the casing  12 , and securing the diverter plate  30  to the casing  12 . 
   In some embodiments, the step of providing a diverter plate  30  may further comprise providing a sheet of material and stamping the sheet to form the baffle wall portion  36 , the aperture(s)  40  and the diverter(s)  50 . In some embodiments, the stamping step may also include forming a flange  32 . 
   In some embodiments, the step of providing a diverter plate  30  may further comprise providing a connecting member  78  and attaching the connecting member  78  to the diverter(s)  50 . In some embodiments, the step of providing a diverter plate  30  may further comprise providing a splitter plate  86  and attaching the splitter plate  86  to the diverter(s)  50   
   In some embodiments, the step of providing the casing  12  may comprise providing a sheet of material and rolling the sheet to form the wall portion  20 . In some embodiments, this may comprise double wrapping the sheet to form a wall portion  20  that is at least two layers thick in all locations. 
   In some embodiments, the step of providing the casing  12  may further comprise providing a first end plate  24  and a second end plate  26 , and attaching the respective end plates  24 ,  26  to the wall portion  20 . 
   The above disclosure is intended to be illustrative and not exhaustive. This description will suggest many variations and alternatives to one of ordinary skill in this field of art. All these alternatives and variations are intended to be included within the scope of the claims where the term “comprising” means “including, but not limited to”. Those familiar with the art may recognize other equivalents to the specific embodiments described herein which equivalents are also intended to be encompassed by the claims. 
   Further, the particular features presented in the dependent claims can be combined with each other in other manners within the scope of the invention such that the invention should be recognized as also specifically directed to other embodiments having any other possible combination of the features of the dependent claims. For instance, for purposes of claim publication, any dependent claim which follows should be taken as alternatively written in a multiple dependent form from all prior claims which possess all antecedents referenced in such dependent claim if such multiple dependent format is an accepted format within the jurisdiction (e.g. each claim depending directly from claim  1  should be alternatively taken as depending from all previous claims). In jurisdictions where multiple dependent claim formats are restricted, the following dependent claims should each be also taken as alternatively written in each singly dependent claim format which creates a dependency from a prior antecedent-possessing claim other than the specific claim listed in such dependent claim below. 
   This completes the description of the preferred and alternate embodiments of the invention. Those skilled in the art may recognize other equivalents to the specific embodiment described herein which equivalents are intended to be encompassed by the claims attached hereto.