Patent Publication Number: US-7905322-B2

Title: Marine muffler with angularly disposed internal baffle

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation in part of U.S. patent application Ser. No. 12/548,548, filed on Aug. 27, 2009, which is a continuation of U.S. patent application Ser. No. 11/891,481, filed Aug. 10, 2007, now U.S. Pat. No. 7,581,620, which claims the benefit of provisional U.S. Patent Application No. 60/837,350, filed Aug. 10, 2006. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     N/A 
     COPYRIGHT NOTICE 
     A portion of the disclosure of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or patent disclosure as it appears in the Patent and Trademark Office patent file or records, but otherwise reserves all copyrights rights whatsoever. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to exhaust systems and mufflers for use with internal combustion marine engines, and more particularly to an improved marine engine muffler having an inclined baffle assembly that provides improved exhaust and water handling capability and enhanced noise reduction. 
     2. Description of Related Art 
     Marine vessels are typically configured with a propulsion system having an internal combustion engine mounted internally within the vessel hull. Exhaust generated by the engine is commonly combined with cooling water and routed through exhaust conduit to the stern or rear of the vessel via one or more exhaust ducts for discharge through one or more exhaust ports formed in the transom. One or more silencers may be installed within the exhaust duct(s) to silence noise associated with the engine and exhaust gases. 
     A variety of structures are known in the background art for use in silencing marine exhaust noise. The present inventor has invented a number of novel marine exhaust components that have greatly improved the silencing and efficiency of marine exhaust systems. Among those inventions developed by a named inventor for the present invention are the following: 
     
       
         
           
               
               
             
               
                   
               
               
                 U.S. Pat. No. 
                 Entitled 
               
               
                   
               
             
            
               
                 4,918,917 
                 Liquid Cooled Exhaust Flange 
               
               
                 5,196,655 
                 Muffler for Marine Engines 
               
               
                 5,228,876 
                 Marine Exhaust System Component Comprising a Heat 
               
               
                   
                 Resistant Conduit 
               
               
                 5,262,600 
                 In-line Insertion Muffler for Marine Engines 
               
               
                 5,444,196 
                 In-line Insertion Muffler for Marine Engines 
               
               
                 5,504,280 
                 Muffler for Marine Engines 
               
               
                 5,616,893 
                 Reverse Entry Muffler With Surge Suppression Feature 
               
               
                 5,625,173 
                 Single Baffle Linear Muffler for Marine Engines 
               
               
                 5,718,462 
                 Muffler Tube Coupling With Reinforcing Inserts 
               
               
                 5,740,670 
                 Water Jacketed Exhaust Pipe for Marine Exhaust 
               
               
                   
                 Systems. 
               
               
                 6,564,901 
                 Muffler for Marine Engine 
               
               
                   
               
            
           
         
       
     
     In U.S. Pat. No. 5,262,600, the first named inventor herein disclosed an in-line insertion muffler for marine engines employing a first housing encompassing a second housing which is partitioned by an angularly disposed inner planar baffle that has proven extremely effective in reducing engine noise. In U.S. Pat. No. 5,444,196, the first named inventor herein disclosed an improved version of the in-line muffler having a corrugated sleeve disposed between in the first and second housings. In U.S. Pat. No. 5,625,173, the first named inventor herein disclosed a single baffle linear muffler with an angularly disposed baffle that may be planer, convex, or concave. 
     The various linear mufflers made in accordance with the above-referenced patents have achieved tremendous success and widespread acceptance within the marine industry. Such muffler systems have been successfully installed on a wide variety of marine vessels having engines in excess of 1,000 horsepower. Current trends in marine vessel design, however, have resulted in reduced or very limited space availability for propulsion system components such as muffler systems. In addition, space limitations present in the retrofit and re-powering of existing marine vessels often present significant space limitations relating to the replacement of muffler systems. While the linear mufflers known in the art are suitable for a wide variety of marine applications, there exists a need for an improved linear muffler that is compact and suitable for use in high horsepower applications. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention overcomes limitations present in the art by providing an improved muffler for marine engines that is compact, and provides improved performance in terms of silencing and backpressure characteristics, as well as ease of manufacturing and installation. A marine muffler comprises an elongate housing having an inlet and an outlet and defining an internal volume. The internal volume is partitioned into upper and lower chambers by an angularly disposed internal baffle, with the lower chamber in communication with the inlet and the upper chamber in communication with the outlet. The baffle is adapted with at least one vertically disposed duct to allow exhaust gas and exhaust cooling water to flow from the lower inlet chamber to upper outlet chamber. The exhaust duct may preferably be further adapted with internal structure forming a plurality of individual non-circular flow conduits or passages. The duct is preferably positioned such that a plurality of flow passage inlets are disposed in proximity to the lower housing wall, with flow passage outlets positioned in proximity to the upper housing wall. The lower duct walls may further be adapted with sidewall apertures for improving exhaust flow dynamics through the duct. Structure is provided to provide rigidity in embodiments that use muffler housings having rectangular cross-sections and/or planar surfaces. 
     Accordingly, it is an object of the present invention to provide a marine muffler adapted with an internal angularly disposed primary baffle. 
     Still another object of the present invention is to provide such a marine muffler wherein the baffle partitions the muffler into a lower inlet chamber and an upper outlet chamber. 
     Yet another object of the present invention is to provide such a muffler wherein the baffle is adapted with a duct in communication with said inlet and outlet chambers. 
     Still another object of the present invention is to provide such a muffler wherein the duct is partitioned into a plurality of sub-passages. 
     Yet another object of the present invention is to provide such a muffler the lower duct wall defines a plurality of apertures to improve water entrainment. 
     Another object of the present invention is to provide a marine muffler having a housing that is generally rectangular to enable the muffler to be installed between the structural elements (e.g. stringers) of the vessel. 
     In accordance with these and other objects, which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a perspective view of a marine engine muffler in accordance with the present invention; 
         FIG. 2  is a side view thereof; 
         FIG. 3  is a side sectional view thereof; 
         FIG. 4  is a top sectional view thereof; 
         FIG. 5  is perspective sectional view thereof; 
         FIG. 6  is a perspective view with partial cut-away of an alternate embodiment of the marine engine muffler having a rectangular housing; 
         FIG. 7  is a side cross sectional view of a portion of the marine engine muffler housing; 
         FIG. 8  is a side sectional view of the marine engine muffler depicted in  FIG. 6 ; 
         FIG. 9  is a top cross sectional view of an alternate embodiment marine engine muffler; 
         FIG. 10  is a perspective view with partial side cut-away of an alternate embodiment having corrugated panels coupled directly to each opposing inner sidewall of the muffler housing; and 
         FIG. 11  is a sectional view thereof. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference now to the drawings,  FIGS. 1-5  depict a preferred embodiment of a muffler, generally referenced as  10 , in accordance with the present invention. Muffler  10  is primarily characterized as having an elongate generally hollow muffler housing  12  formed about a longitudinal axis with opposing ends forming an open inlet  14  and an open outlet  16 . In a preferred embodiment, housing  12  comprises a generally cylindrical structure fabricated from composite material such as temperature resistant fiberglass. While the preferred embodiment is disclosed with a housing that is generally cylindrical, the present invention is suitable for use with housings having various shapes. As best depicted in  FIG. 3 , muffler housing  12  defines an internal volume and includes an angularly disposed baffle  20 , having a peripheral edge in sealing engagement with the inner surface of housing  12 , which divides the internal volume into a lower inlet chamber  22  and an upper outlet chamber  24 . In a preferred embodiment baffle  20  is generally planar, however, any suitable shape, such as concave or convex, is contemplated and considered within the scope of the present invention. Baffle  20  is angularly disposed and preferably oriented to extend angularly downward from an upper inner surface of housing  12  proximal muffler inlet  14  to a lower inner surface of housing  12  proximal muffler outlet  16 . Accordingly, exhaust entering the muffler enters the inlet chamber  22 , which chamber is defined by the lower surface of baffle  20  and the internal muffler housing wall. Inlet  14  may further be adapted with a generally upwardly angled lip  14 A. Upwardly angled lip  14 A functions to attenuate exhaust pressure waves while deflecting exhaust upward toward the underside of baffle  20 . 
     Secured to baffle  20  is a generally vertically disposed duct  30  having open top and bottom ends, referenced as  32  and  34  respectively, terminating in spaced relation with the inner surface of housing  12 . Duct  30  functions to allow exhaust gas and cooling water entrained therewith to flow from the inlet chamber  22  to the outlet chamber  24 . Duct  30  may preferably be further adapted with an internal wall structure  36  forming a plurality of individual flow conduits or passages, referenced as  37 . In a preferred embodiment, wall structure  36  is fabricated from a corrugated composite panel, however, any partition structure is considered within the scope of the present invention. Duct  30  is preferably generally vertically disposed and positioned such that a plurality of duct inlets  37 A formed at the bottom thereof are positioned in spaced proximity to the lower inner surface of cylindrical housing  12 . Similarly, duct outlets, referenced as  37 B, are positioned in spaced proximity to the upper inner surface of cylindrical housing  12 . The bottom end portion  34  of duct  30  may further be adapted with sidewall apertures  38  for improving exhaust flow dynamics through the duct. Sidewall apertures  38  may be formed for each flow passage, and may be staggered in height from one passage to the other as depicted in  FIG. 4 . The use of sidewall apertures  38  has been found significant in improving exhaust gas flow dynamics and the entrainment of water through duct inlets at the bottom  34  of duct  30 . 
     As best illustrated in  FIG. 3 , exhaust gas and exhaust cooling water enter the inlet chamber  22  of muffler  10  via inlet  14  whereby angled lip  14 A deflects at least a portion of the exhaust gas and cooling water upward toward the undersurface of inclined baffle  20  thereby increasing the effectiveness of sound attenuation by disrupting the incoming pressure waves. Under certain conditions wherein the engine is operating at relatively low RPM&#39;s, it is expected that exhaust gas cooling water will begin to pool on the housing floor within inlet chamber  22 . As the water level rises and chokes the flow paths to the duct inlets, the exhaust gas velocity will naturally increase thereby causing entrainment of the water with the exhaust gas. It has been found that sidewall apertures  38  significantly enhance the entrainment of water within the exhaust gas flow stream. The exhaust gas and water exit duct  30  through outlets at the top  32  of duct  30  into outlet chamber  24  whereafter the exhaust gas and entrained cooling water are allowed to exit via muffler outlet  16 . A muffler in accordance with the present invention may be fabricated from composite material, such as heat resistant fiberglass, or any other suitable material. 
     Alternate Embodiments 
       FIGS. 6-9  depict an alternate embodiment of a marine muffler, generally referenced as  50 , in accordance with the present invention. Muffler  50  includes an elongate hollow generally rectangular housing  52 . Housing  52  includes exhaust inlet opening  54  and an exhaust outlet opening  56  disposed on opposing sides along the longitudinal axis of the muffler housing  52  to allow for the flow of exhaust and cooling water through the muffler  50 . The generally rectangular shape of the muffler housing  52  is advantageous in that it allows for the mounting of the muffler  50  in an easy and effective manner within the generally rectangular shaped cavity that is formed between the stringer supports that run lengthwise in the hull of the vessel. Providing a rectangularly shaped muffler that fits between stringer supports effectively maximizes use of space over mufflers having cylindrical shapes. In addition to easy mounting, the rectangular shaped muffler  100  conserves space for other instruments within the hull of the boat, by fitting precisely into the compact region that is defined by the supports within the hull. 
     As best illustrated by  FIGS. 6 and 7 , muffler  50  includes a hollow rectangular shaped housing  52  that defines a contained volume which includes an angularly disposed (e.g. inclined) baffle  58 . Baffle  58  is generally rectangular in shape, such that the peripheral edges of the baffle  58  are in contact with the inner walls of the housing in a sealed configuration. The angular disposition of the baffle  58  is created, such that the periphery of one longitudinal end of the baffle  58  is coupled in a sealed configuration to the inner surface of the top wall of the muffler housing  52  at a point in proximity to the inlet opening  54 , and the opposing longitudinal end of the periphery of the baffle  58  is coupled in a sealed configuration to the inner surface of the bottom wall of the muffler housing  52  at a point in proximity to the outlet opening  56 . Through the angular configuration, the baffle  58  divides the contained volume within the muffler housing  52  into a lower chamber  60  and an upper chamber  62 . The lower chamber  60  is defined as the region of the contained inside chamber that is directly adjacent to the inlet opening  54  formed between the bottom of the angularly disposed baffle  58  and the inner surface of the lower wall of the muffler housing  58 , through which exhaust and cooling liquid flows into the muffler  50 . The upper chamber  62  is defined as the region of the contained inside chamber that is directly adjacent to the outlet opening  56  formed between the top of the baffle  58  and the inner surface of the upper wall of the muffler housing  58 , through which exhaust and cooling liquid flow out from the muffler  50 , Baffle  58  is preferably fabricated from a solid material that is impervious to water and gas penetration. In a contemplated alternate embodiment, however, baffle  58  is fabricated from material that may be penetrated by water and/or gas. In such an embodiment, baffle  58  provides significant reduction in emissions by essentially absorbing fluid or particulate matter, similar to an air filter. 
     As best seen in  FIGS. 6 and 8 , a plurality of support beams  62 , extend longitudinally across substantially the entire longitudinal length of the baffle  58 , with the top and bottom portions of the beams being rigidly connected to the upper and lower housing walls. In a preferred embodiment, support beams  62  comprise I-beam type beams so that the flanges that extend out from the top and bottom of the support beams  62  are rigidly secured in a flushed configuration against the inner surface of the upper and lower walls of the muffler housing  52 . Beams  62  function to add rigidity to the planar housing walls. This structure is considered significant since, if left un-reinforced, the planar housing walls would otherwise be subject to excessive vibration resulting from the exhaust gas pulsation. It is for that reason, that most marine mufflers known in the art utilize cylindrical housings. The present invention thus overcomes the cylindrical housing limitation by, in one embodiment, using a rectangular housing with reinforced/stiffened walls. Beams  62  are preferably configured in a parallel configuration, such that the baffle  58  bisects each beam  62  along the diagonal formed between upper and lower corners on opposing side of each support beam  62 . The beams  62  serve to support the baffle  58  in an angled position and also serve to make the muffler  50 , including both the housing  52  and the baffle  58 , more rigid. By making the muffler  50  more rigid, vibrations caused by the pressurized waves created by exhaust flow dynamics through the muffler  50  are dampened, thereby reducing the noise of the muffler  50  and the corresponding overall exhaust system. 
     At least one duct  64 , and preferably a series of ducts, are disposed vertically along the sides of the beams  64  that extend between the inner surfaces of the upper and lower walls of the muffler housing  52 , while terminating in spaced relation with the upper and lower walls. Each duct  64  extends through the upper and lower surfaces of the baffle  58  thereby providing a flow conduit for exhaust gas and cooling water to travel from the lower chamber to the upper chamber. In a preferred embodiment, each duct  64  is made up of a corrugated panel that is coupled in a vertical configuration directly to the side walls of the beam support  62 , however, in a contemplated alternate embodiment the duct may simply comprise one or more hollow tubular members the penetrate through the baffle. Through the use of a corrugated panel in creating the ducts, a series of flow conduits and passageways  66  are created. The corrugated panel that is used to create each duct  64  extends through the top and bottom of surfaces of the angled baffle  58 , such that the flow conduits  66  extend between the lower and upper chambers  60  and  62  that are created by the angled baffle  58 . In extending through the angled baffle  58 , the corrugated panel creates a series of passageway inlet openings  66 A in the lower chamber  60  and a series of passageway outlet openings  66 B in the top chamber, allowing for the dynamic flow of exhaust and cooling liquid through the muffler  50 . 
     The corrugated panel can also include a series of sidewall apertures that extend through the panel in the lower chamber  60  at positions directly adjacent to each passageway inlet openings  66 A. These sidewall apertures can be staggered in height positioning along the corrugated panel. The use of sidewall apertures in the passageway  66  of the present invention, helps to insure that the exhaust and cooling liquid can flow into the passageway, thereby ensuring that a flow of exhaust is created through the muffler  50 , even when the inlet openings  66 A are submerged under cooling liquid that collects at the bottom of the lower chamber  60 . In particular, the cooling liquid pools on the floor of the lower chamber  60  of the muffler  50  when the engine is operated at low RPM&#39;s. 
     As with previous embodiments, in the operation of the muffler and as best illustrated by  FIGS. 8 and 9 , the exhaust and cooling liquid flows into the muffler through the inlet opening  54 . The device can include an angled lip at the inlet opening  54  to deflect the pressure waves created by the exhaust flow dynamics, thereby further increasing the effectiveness of the sound attenuation ability of the muffler  50 . An example of such a lip structure is shown in the primary embodiment, referenced as  14 A depicted in  FIG. 3 . After entering into the lower chamber  60  of the muffler  50 , the exhaust flow dynamic collides with the angled baffle  58  and is subsequently pushed down toward the bottom of the lower chamber. The exhaust and coolant flow then proceeds into the passageways  66  that are created by the corrugated panel through either the sidewall apertures or the passageway inlet openings  66   a . The exhaust and coolant flow is directed into the upper chamber  62  through the passageway outlet opening  66   b  and out of the upper chamber through the outlet duct opening  56 . By redirecting the exhaust flow dynamics through a series of passageways  66  within a duct  64 , the pressure waves that are created by the flow of the exhaust and cooling liquid are disrupted, thereby effectively attenuating the sound waves that are associated with the pressure waves. 
       FIGS. 10 and 11  disclose an alternate embodiment muffler, generally referenced as  70 , wherein a series of ducts, created by a corrugated panel that is coupled directly to each opposing inner sidewall of the muffler housing, are formed. Muffler  70  includes an elongate hollow generally rectangular housing  72 . Housing  72  includes exhaust inlet opening  74  and an exhaust outlet opening  76  disposed on opposing sides along the longitudinal axis of the muffler housing  72  to allow for the flow of exhaust and cooling water through the muffler  70 . The generally rectangular shape of the muffler housing  72  is advantageous in that it allows for the mounting of the muffler  70  in an easy and effective manner within the generally rectangular shaped cavity that is formed between the stringer supports that run lengthwise in the hull of the vessel. Providing a rectangularly shaped muffler that fits between stringer supports effectively maximizes use of space over mufflers having cylindrical shapes. In addition to easy mounting, the rectangular shaped muffler  70  conserves space for other apparatus within the hull of the boat, by fitting precisely into the compact region that is defined by the supports within the hull. 
     Muffler  70  includes a hollow rectangular shaped housing  72  that defines a contained volume which includes an angularly disposed baffle  78 . Baffle  78  is generally rectangular in shape, such that the peripheral edges of the baffle  78  are in contact with the inner walls of the housing in a sealed configuration. The inclined disposition of the baffle  78  is created, such that the periphery of one longitudinal end of the baffle  78  is coupled in a sealed configuration to the inner surface of the top wall of the muffler housing  72  at a point in proximity to the inlet opening  74 , and the opposing longitudinal end of the periphery of the baffle  78  is coupled in a sealed configuration to the inner surface of the bottom wall of the muffler housing  72  at a point in proximity to the outlet opening  76 . Through the angular configuration, the baffle  78  divides the contained volume within the muffler housing  72  into a lower chamber  80  and an upper chamber  82 . The lower chamber  80  is defined as the region of the contained inside chamber that is directly adjacent to the inlet opening  74  formed between the bottom of the angularly disposed baffle  78  and the inner surface of the lower wall of the muffler housing  72 , through which exhaust and cooling liquid flows into the muffler  70 . The upper chamber  82  is defined as the region of the contained inside chamber that is directly adjacent to the outlet opening  76  formed between the top of the baffle  78  and the inner surface of the upper wall of the muffler housing  72 , through which exhaust and cooling liquid flow out from the muffler  70 . Baffle  78  is preferably fabricated from a solid material that is impervious to water and gas penetration. In a contemplated alternate embodiment, however, baffle  78  is fabricated from material that may be penetrated by water and/or gas. In such an embodiment, baffle  78  provides significant reduction in emissions by essentially absorbing fluid or particulate matter, similar to an air filter. 
     In the embodiment depicted in  FIG. 10 , corrugated panel  90  is attached to the inner surface of side walls of housing  72  so as to from a plurality of generally vertically disposed ducts, referenced as  92  in close proximity to the inner side walls of housing  72 . Ducts  92  extend between the inner surfaces of the upper and lower walls of the muffler housing  72 , while terminating in spaced relation with the upper and lower walls. Each duct  90  extends through the upper and lower surfaces of the baffle  78  thereby providing a flow conduit for exhaust gas and cooling water to travel from the lower chamber to the upper chamber. Corrugated panel  90  that is used to create duct  92  extends through the top and bottom of surfaces of the angled baffle  78 , such that the ducts  92  form flow conduits extending between the lower and upper chambers  80  and  82 . In extending through the angled baffle  58 , the corrugated panel creates a series of duct inlet openings  92 A in the lower chamber  80  and a series of duct outlet openings  92 B in the top chamber, allowing for the dynamic flow of exhaust and cooling liquid through the muffler  70 . The present inventor has found that by forming ducts  92  in a non-circular cross-sectional shape improves exhaust silencing by disrupting pressure wave propagation through muffler  70 . 
     The corrugated panel can also include a series of sidewall through bore apertures  93  that extend through the panel in the lower chamber  80  at positions directly adjacent or in proximity to each duct inlet openings  92 A. Sidewall apertures  93  can be staggered in height positioning along the corrugated panel. The use of sidewall apertures in the proximity to duct openings  92 A helps to ensure that the exhaust and cooling liquid can flow into the passageway, thereby ensuring that a flow of exhaust is created through the muffler  70 , even when the inlet openings  92 A are submerged under cooling liquid that collects at the bottom of the lower chamber  80 . In particular, the cooling liquid pools on the floor of the lower chamber  80  of the muffler  70  when the engine is operated at low RPM&#39;s. 
     A further significant advancement present in the embodiment depicted in  FIGS. 10 and 11 , relates to the affixation of arcuate panels, namely a top arcutate insert panel  79  and a bottom arcuate insert panel  80 , that are affixed within housing  72  in generally parallel relation with the inner top and bottom surfaces so as to form generally convex inner top and bottom surfaces. Arctuate panels  79  and  80  function to provide convex surfaces within the housing for reflecting pressure waves, while further functioning to stiffen the top and bottom housing walls so as to prevent excessive vibration that would result in increased noise propagation. Accordingly, the use of arcuate panels  79  and  80  provide an alternate upper and lower housing stiffening structure as compared to I-beam structures found in the embodiment depicted in  FIGS. 6-9 , while affixation of the corrugated panels to opposing sides of the housing provides stiffening structure to the housing side walls. 
     The instant invention has been shown and described herein in what is considered to be the most practical and preferred embodiment. It is recognized, however, that departures may be made therefrom within the scope of the invention and that obvious modifications will occur to a person skilled in the art.