Abstract:
A noise muffler for the exhaust of waste gases from apparatus such as an oxygen concentrator, including a muffler core with an inlet to receive the waste gases and a plurality of bores in the core first to direct the waste gases through a filter material and a cap enclosing the filter material and forming a plurality of outlets to direct the waste gases out of the muffler, the bores and outlets positioned to cause the waste gases to change their direction of flow multiple times before exiting the muffler.

Description:
FIELD OF THE INVENTION 
     This invention relates to noise mufflers for the exhaust of gas handling apparatus. 
     BACKGROUND OF THE INVENTION 
     Gas handling apparatus such as oxygen concentrators are often used in medical applications by patients that have difficulty breathing. Whether the oxygen concentrator is used by a patient in a hospital or in the home, the noise output by the oxygen concentrator is an important consideration, especially when the patient and those nearby are trying to sleep. A significant contributor to the noise made by an oxygen concentrator is the noise made by the exhaust of the oxygen concentrator. Therefore, an improved noise muffler for the exhaust of an oxygen concentrator is desired in the art. Further, oxygen concentrators are usually required to be somewhat portable to enable patient mobility. Therefore, a noise muffler having a simple, compact, and durable design is further desired in the art. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved noise muffler for the exhaust of a gas handling apparatus. 
     The invention comprises, in one form thereof, a substantially cylindrical core having an inner core surface, an outer core surface, an open end, and a closed end. A plurality of radial bores connects the inner core surface with the outer core surface. A flange is integral with or affixed to the closed end of the core. A filter comprising woven or non-woven polymer fibers surrounds the core and abuts the flange. 
     The noise muffler further includes a substantially cylindrical cap having an inner cap surface engaging the filter, a first end including a plurality of clips penetrating the flange, and a covered end opposite to the first end of the cap. The open end of the core penetrates the covered end of the cap. A plurality of outlets is formed between the first end of the cap and the flange and between the plurality of clips of the cap. 
     The noise muffler of the present invention provides a compact and lightweight muffler for gas handling systems and consists of a minimum number of parts. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become apparent and be better understood by reference to the following description of one embodiment of the invention in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is an isometric view of the noise muffler of the present invention; 
         FIG. 2  is a second isometric view of the noise muffler as taken on line  3 — 3  of  FIG. 2 ; 
         FIG. 3  is a cross-sectional view of the noise muffler of  FIG. 1 ; 
         FIG. 4  is an isometric view of the muffler cap of  FIG. 1 ; 
         FIG. 5  is a second isometric view of the muffler cap of  FIG. 4 ; 
         FIG. 6  is a cross-sectional view of the muffler core of  FIG. 1   
         FIG. 7  is a view of section  7 — 7  of the muffler core of  FIG. 5 ; 
         FIG. 8  is a side view of the muffler core of  FIG. 5 ; 
         FIG. 9  is an isometric view of the filter of  FIG. 3 ; and 
         FIG. 10  is a cross-sectional view of the noise muffler as taken on line  10 — 10  of FIG.  2  and rotated 45 degrees relative to the cross-sectional view of FIG.  3 . 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate the preferred embodiments of the invention and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , there is shown the noise muffler of the present invention. The noise muffler  10  includes a muffler cap  12 , a muffler core  14 , and a filter  16  shown in FIG.  3 . 
     Referring now to  FIGS. 4 and 5 , muffler cap  12  includes a substantially cylindrical wall  20 , a covered end  22 , a plurality of clips  24 , and a plurality of recesses or outlets  25 . The covered end  22  is integral with or affixed to the cylindrical wall  20  and includes an axial through hole  26 . The clips  24  are integral with or affixed to the cylindrical wall  20  and each clip  24  includes an outward pointing lip  28 . The muffler cap  12  is shown having four clips  24 , however any number of clips may be used. A plurality of ribs  29  are integral with or affixed to the outer surfaces of the cylindrical wall  20  and the covered end  22 . The ribs  29  add strength to the muffler cap  12 . 
     Referring now to  FIG. 6 , the muffler core  14  includes a flange  30  and a central piece  32 . The flange  30  includes a central blind bore  31  being configured for engaging a hexagonal wrench. The flange  30  further includes a plurality of slots  34  configured for engaging the clips  24 . Each of the slots  34  includes an inner edge  35 . The central piece  32  is integral with the center of the side of the flange  30  opposite to the central blind bore  31 . The central piece  32  includes a threaded end  36 , an axial blind bore  38 , and a plurality of radial bores  40 . The axial blind bore  38  has a decreasing diameter from the threaded end  36 . Each row of radial bores has five radial bores  40  as shown in the drawings, however different applications may require a different number of radial bores  40 . Further, as shown in  FIG. 7 , the central piece  32  includes 4 rows of radial bores  40 ; however, the number of rows of radial bores  40  may be different for particular applications. Each of the radial bores  40  has an increasing diameter from the axial blind bore  38 . In the preferred embodiment, the size and number of the radial bores  40  provide ample flow from the axial blind bore  38  to thereby reduce any backpressure within the axial blind bore  38 . As best seen in  FIGS. 7 and 8 , a plurality of depressions  42  are located between the rows of radial bores  40  to reduce the weight and material used in the central piece  32 . 
     As seen in  FIG. 9 , the filter  16  is substantially cylindrical and includes and axial bore for engaging the central piece  32 . The outer radius of the filter  16  is greater than the distance from the axis of the flange  30  to the inner edges  35  of the slots  34 . The filter  16  is made of felt or a similar material comprising polymer fibers formed into a firm cloth. 
     In use, the filter  16  is placed on the central piece  32  such that the inner surface of the filter  16  contacts the radial bores  40  and one end of the filter  16  abuts the flange  30 . As shown in  FIG. 3 , the muffler cap  12  slides over the filter  16  such that the inner surface of the cylindrical wall  20  contacts the filter  16 . The threaded end  36  of the central piece  32  slides through the through hole  26  of the muffler cap  12  until the clips  24  snap into the slots  34 . The outward pointing lips  28  engage the outer surface of the flange  30 . In the preferred embodiment, the interface  44  between the central piece  32  and the through hole  26  of the muffler cap  12  is tapered and has an interference fit of approximately 0.002-in. Referring to FIG.  1  and  FIG. 10 , the assembled noise muffler  10  forms outlets  25 . 
     The threaded end  36  of the central piece  32  is threaded onto the exhaust of a gas handling apparatus such as an oxygen concentrator. A secure fit is achieved by tightening the muffler core  14  with a wrench such as a hexagonal wrench engaging the central blind bore  31  of the flange  30 . The pressurized exhaust gas enters the noise muffler  10  through the axial blind bore  38  and proceeds to the radial bores  40 . The gas then passes from the radial bores  40  to the filter  16 . The polymer fibers of the filter  16  absorb the kinetic energy of the gas, thereby slowing it down. The gas exits the noise muffler  10  through the outlets  25  with less energy and therefore, quietly. Further, the two directional changes applied to the flow by the noise muffler  10  reduces the noise of the gas flow. 
     It should be particularly noted that because of the integral nature of the muffler core  14 , the noise muffler  10  is comprised of only a few readily molded parts and is therefore inexpensive and easy to manufacture. Preferably, the muffler cap  12  and the muffler core  14  are made of a substantially rigid material such as steel, aluminum, polyethylene, or polycarbonate. Moreover, the central blind bore  31  of the flange  30  may be alternatively configured for engaging a tool other than a hexagonal wrench, such as a screwdriver. Further, the flange  30  may include a protrusion having a plurality of flat sides rather than a blind bore. A noise muffler including such a protrusion may be tightened using tools such as pliers, an open-end wrench, a box wrench, or a socket wrench. 
     While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the scope of the invention. 
     Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope and spirit of the appended claims.