Patent Application
20070284187
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting.
Before proceeding, it should be noted that the term “small engine” as used herein generally refers to an internal combustion engine that includes one or two cylinders. The engine can be arranged with a horizontal or a vertical crankshaft as may be required. While the invention discussed herein is particularly suited for use with small engines, one of ordinary skill in the art will realize that it could be applied to larger engines (i.e., three or more cylinders) as well as other engine designs (e.g., rotary engine, radial engine, diesel engines, combustion turbines, and the like). In fact, the invention could be applied to virtually any flow stream in which a reduction in noise is desired. As such, the invention should not be limited to the small engine application described herein.
With continued reference to
The housing 35 defines a surface 50 having the outlet aperture 40. The surface 50 has a muffler flange 55 that receives the exhaust deflector 30 such that the outlet aperture 40 is in fluid communication with the exhaust deflector 30.
It should be noted that
The first wall 70 is a substantially cylindrical wall that extends a first non-zero distance 90 from the flange 65. In the illustrated construction, the first wall 70 is normal to the flange 65. However, other constructions may employ a different angle between the flange 65 and the first wall 70 as required for the particular application. In addition, while a cylindrical wall having a circular cross section has been illustrated, other constructions may employ other shapes. For example, an oval or elliptical cross section could be employed. In addition, polygonal cross section walls, or irregular shaped walls could also be employed if desired.
The second wall 75 extends from the first wall 70 and defines an outlet aperture 95. As illustrated, the second wall 75 is substantially normal to the first wall 70, and thus substantially parallel to the flange 65. In the illustrated construction, the second wall 75 defines a substantially planar surface, with other constructions employing non-planar second walls 75. The outlet aperture 95 includes a large opening approximately centered in the second wall 75. Of course, other constructions may employ multiple smaller apertures that cooperate to define the outlet aperture 95 and may include a second wall 75 that is not substantially normal to the first wall 70.
The collar 80, shown in
In preferred constructions, the housing 60—including the flange 65, the first wall 70, the second wall 75, and the collar 80—is integrally-formed as a single piece. For example, in one construction, the housing 60 is formed by stamping, drawing or otherwise forming a metal sheet. In other constructions, the housing 60 is cast or otherwise formed. In still other constructions, multiple separate pieces are attached to one another (e.g., welded, soldered, brazed, and the like) to complete the housing 60.
As illustrated in
Turning to
The second mesh wall 115 extends from the first mesh wall 110 and is substantially parallel to the flange 65. The second mesh wall 115 extends inward from the first mesh wall 110 to define an annular surface that includes an aperture 135 that is slightly larger than the outlet aperture 95. Of course many variations of this arrangement are possible. For example, the aperture 135 could be larger or smaller than that illustrated. In addition, the second mesh wall 115 could be arranged with respect to the first mesh wall 110 to define a non-normal angle.
The third mesh wall 120 extends from the second mesh wall 115 to the housing second wall 75. In the illustrated construction, the third mesh wall 120 is substantially parallel to the housing first wall 70 and is spaced apart from the housing first wall 70. Again, other arrangements and angles of the third mesh wall 120 are possible.
The third mesh wall 120 is substantially cylindrical and extends from the second mesh wall 115 to the outlet aperture 95. The aperture-covering portion 125 extends across the circular opening defined by the third mesh wall 120 adjacent the outlet aperture 95 to cover the aperture 95.
In preferred constructions, a single piece of mesh material 100 is used. Again, the mesh material 100 could be formed using a number of manufacturing techniques including stamping, drawing, progressive dies, and the like. Generally, a mesh 100 having a plurality of openings with an average opening area of 1 square millimeter per opening is preferred. However, meshes including larger average opening areas or smaller average opening areas are also possible.
With reference to
During engine operation, hot exhaust gas passes from the cylinder to the muffler inlet 45, through the muffler chamber, to the outlet 40. The muffler chamber reduces the magnitude of the noise produced by the engine 15. From the muffler outlet 40, the air enters the exhaust deflector 30. As the exhaust gas passes through the exhaust deflector 30, the gas substantially flows past the low-density material 145 and through the mesh 100 to the outlet aperture 95. Sound pressure waves are dissipated as they freely pass though the mesh 100 into the low-density material 145. Additionally, the reactive properties of the mesh 100 and the housing 60 contribute to noise reduction. Thus, the exhaust deflector 30 changes the acoustic impedance and further reduces the noise produced by the engine 15.
The arrangement of the mesh 100 is such that any forces produced by the flow of exhaust gas through the exhaust deflector 30 tend to hold the mesh 100 in the desired position. As such, additional support for the mesh 100, or attachment points for the mesh 100 are generally unnecessary.
Thus, the invention provides, among other things, a new and useful exhaust deflector 30 for a muffler 20. More specifically, the invention provides an exhaust deflector 30 that further reduces the noise produced by an internal combustion engine 15.
