Abstract:
A muffler device, in one preferred embodiment, having four barriers therein. Each barrier functions to form an within which the exhaust stream can be partitioned and redirected. Eventually, the exhaust streams are once again recombined and expelled from the muffler. The partitioning and reassembly of the exhaust streams provides sound attenuation while increasing the horsepower of the engine and without resulting in any build up of unignited fuel.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to the field of mufflers for internal combustion engines in general, and specifically to mufflers in which sound attenuation is achieved with a minimum back-pressure thereby resulting in increased engine horsepower.  
         BACKGROUND OF THE INVENTION  
         [0002]    Mufflers have been developed for the attenuation of the sound component in an exhaust gases from an internal combustion engine which employ sound-attenuating partition configurations that produce low-pressure regions or volumes within the muffler. The low-pressure volume can be the result of cancellation of identical sound frequencies by directing streams of gas to collide against each other, or can be the result of fluid flow patterns through the muffler, or both.  
           [0003]    The flow of exhaust gases through a muffler is not in a steady stream of the type which exits a garden hose. Instead, each time an exhaust valve opens, a pulse of exhaust gases is discharged into the exhaust system. Thus, flow of exhaust gases through a muffler is comprised of a series of volume pulses in which there are fully combusted gases, live fire or burning fuel and, in some cases, fuel which is unignited and will not contact or mix sufficiently with the burning fuel to ignite.  
           [0004]    When these exhaust components reach the muffler, the muffler partitions typically quench or retard further burning of unignited fuel rather quickly. The result is that a small volume of unignited fuel may be present in the muffler. If the muffler includes low-pressure regions or volumes, there will be a tendency for this unignited fuel to accumulate in such regions.  
           [0005]    The presence of a low-pressure volume in a muffler, nevertheless, is highly desirable since in some muffler configurations it has been found to increase engine horsepower. It is believed that the low-pressure region in the muffler is “seen” upstream in the exhaust system to the engine. The low pressure in the muffler scavenges or accelerates the movement of exhaust gas pulses in the exhaust system. Thus, pulses proximate the low-pressure volume are accelerated toward it, which, in turn, accelerates pulses farther upstream. Finally, when the engine exhaust valve opens to exhaust gases from the cylinder, these gases are exhausted into a lower pressure exhaust system than would be present if the muffler did not have low-pressure volumes in it. This slightly lower pressure at the exhaust valve enables the same volume of gases to be exhausted from the cylinder in a slightly shorter period of time. This, in turn, allows the engine to be tuned to keep the exhaust-valve closed slightly longer, which allows the engine to develop additional horsepower.  
           [0006]    The accumulation of unignited fuels in mufflers having low-pressure volumes can present a problem which ranges from annoying to potentially dangerous. Under most operating conditions such fuels are either not accumulated or are dissipated. However, under some conditions explosive detonations or rapid combustion can occur. Such muffler explosions can range from disconcerting popping sounds during deceleration to violent explosions which damage the muffler and exhaust system.  
           [0007]    Therefore, there remains a long standing and continuing need for an advance in the art of mufflers that is simpler in both design and use, is more effective in allowing an increase in horse power while eliminating the possibility of popping sounds or even explosions, and is cost efficient in its construction and use.  
         SUMMARY OF THE INVENTION  
         [0008]    Accordingly, it is a general object of the present invention to overcome the disadvantages of the prior art.  
           [0009]    In particular, it is an object of the present invention to provide a sound-attenuating muffler for an internal combustion engine or the like, and method, which prevents the accumulation of unignited fuel in low-pressure volumes in the muffler without significantly decreasing the sound-attenuating capacity of the muffler.  
           [0010]    It is another object of present invention to provide a sound-attenuating muffler and method which prevents accumulation of unignited fuel in the muffler without decreasing the enhanced engine performance produced by the muffler.  
           [0011]    It is a further object of the present invention to provide a sound-attenuating muffler which prevents accumulation of unignited fuels in the muffler, yet is still compact and durable, has a minimum number of components and is economical to manufacture.  
           [0012]    In keeping with the principles of the present invention, a unique muffler is herein disclosed having a first, second, third and fourth barrier in one preferred embodiment. Each barrier functions to form a compartment within which the exhaust stream can be partitioned and redirected. Eventually, the exhaust streams are once again recombined and expelled from the muffler. The partitioning and reassembly of the exhaust streams provides sound attenuation while increasing the horsepower of the engine and without resulting in any build up of unignited fuel.  
           [0013]    Such stated objects and advantages of the invention are only examples and should not be construed as limiting the present invention. These and other objects, features, aspects, and advantages of the invention herein will become more apparent from the following detailed description of the embodiments of the invention when taken in conjunction with the accompanying drawings and the claims that follow. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    It is to be understood that the drawings are to be used for the purposes of illustration only and not as a definition of the limits of the invention.  
         [0015]    In the drawings, wherein similar reference characters denote similar elements throughout the several views:  
         [0016]    [0016]FIG. 1 is perspective view of a muffler device in an assembled state.  
         [0017]    [0017]FIG. 2 is a frontal top perspective view of the muffler device with a top thereof removed.  
         [0018]    [0018]FIG. 3 is a first side top perspective view of the muffler device with the top thereof removed.  
         [0019]    [0019]FIG. 4 is a second side top perspective view of the muffler device with the top thereof removed.  
         [0020]    [0020]FIG. 5 is a top perspective view of the muffler device with the top thereof removed and illustrating pulse flow.  
         [0021]    [0021]FIG. 6 is a rear top perspective view of the muffler device with the top thereof removed.  
         [0022]    [0022]FIG. 7 is a top perspective view of an alternate preferred embodiment of the muffler device also illustrating pulse flow. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0023]    Referring to FIGS. 1 through 4, therein is illustrated a muffler device generally designated by the number  10  and having a generally rectangular shape. However, it is to be understood that the shape of device  10  may be altered without departing from the essence of the invention. In addition, the materials described and the dimensions given can be modified to accommodate different engines and physical requirements of other types of vehicles with which device  10  may be used. Device  10  has an inlet conduit  12  and an outlet conduit  14  attached to an inlet wall  16  and an outlet wall  18  respectively, through which walls said conduits  12  and  14  traverse and allow communication there through. Inlet wall  16  and outlet wall  18  are interconnected by a first sidewall  20  and a second sidewall  22 . A top  24  and a bottom  26  extend over walls  16 ,  18 ,  20 , and  22  on opposing sides thereof and enclose the same.  
         [0024]    Now also referring to FIGS. 5 through 7, arrow  28  illustrates incoming exhaust pulse from an internal combustion engine (not shown) which travels through a first opening  29  defined through inlet wall  16  via inlet conduit  12 . At arrows  30 , the exhaust pulse is split into two streams as a result of a first barrier  32 . First barrier  32  extends between first sidewall  20  and second sidewall  22  and top  24  and bottom  26  such that a first compartment  34  is formed between first barrier  32  and the inlet wall  16 . A first aperture  36  and a second aperture  38  are defined through said first barrier  32 . In one preferred embodiment, first aperture  36  has a larger diameter than second aperture  38 , and both apertures  36  and  38  are not axially aligned with opening  29 . In a preferred embodiment, opening  29  is located proximal to first sidewall  20  and first aperture  36  is substantially centrally located within first barrier  32  and second aperture  38  is located proximal to second sidewall  22 . It is to be understood that the location of inlet conduit  12  may be altered and as a result the location of first and second apertures  36  and  38  may also be shifted such that axial alignment with opening  29  is avoided. However, second aperture  38  may also be in axial alignment with opening  29  because of its narrower diameter when compared with first aperture  36  without affecting the functioning of device  10 .  
         [0025]    A second barrier  40  is located more distal to inlet wall  16  than first barrier  32  and also extends between first side wall  20 , second side wall  22 , top  24  and bottom  26  such that a second compartment  42  is formed between first barrier  32  and second barrier  40 . A first hole  44  is defined through second barrier  40  and is in substantial axial alignment with first aperture  36  of first barrier  32 . In one preferred embodiment, the diameter of first hole  44  is shorter than the diameter of first aperture  36 . A second hole  46  is also defined through second barrier  40  and is in substantial axial alignment with second aperture  38 . In one preferred embodiment, the diameter of second hole  46  and second aperture  38  are substantially equal, but may also be of differing size without departing from the essence of the invention. A third hole  48  is also defined through second barrier  40  and is located between first hole  44  and first sidewall  20 . In one preferred embodiment, third hole  48  is smaller in diameter than first hole  44  and is substantially the same size as second hole  46 .  
         [0026]    A first conduit  50  extends from first barrier  32  to second barrier  40  and is aligned between first aperture  36  and first hole  44 . A second conduit  52  extends form first barrier  32  to second barrier  40  and is aligned between second aperture  38  and second hole  46 . The Second conduit  52  receives the exhaust pulse split at arrow  30  at second aperture  38 , the pulse travels through conduit  52  and is expelled from second hole  46  as indicated by arrow  54 .  
         [0027]    First conduit  50  receives the exhaust pulse that is split at arrow  30  at first aperture  36  and the pulse travels into conduit  50 . Within conduit  50 , a plurality of voids  56  are created along the axis thereof on a side opposing conduit  52 . The diameter of each void  56  is approximately one eighth of an inch, however it is to be understood that the diameter of the void may be altered or the number of voids  56  may be added or subtracted without departing from the essence of the invention. As a result of the voids  56 , the exhaust pulse  30  is further split into two streams wherein the pulse traveling out of conduit  50  through first hole  44  is represented by arrow  58  and the pulse traveling out of conduit  50  through voids  56  are represented by arrow  60 . The pulse stream indicated by arrows  60  enters second compartment  42 , wherein they are brought back together at a point indicated by arrow  62 .  
         [0028]    A third conduit  64  extends from second barrier  40  at a first end  66  and has a second end  68  distal thereto. Second end  68  receives the exhaust pulse indicated at arrow  62  within second compartment  42  and allows communication between second compartment  42  and a third compartment  70 . The exhaust pulse  62  is expelled from third conduit  64  into third compartment  70 .  
         [0029]    A third barrier  72  and second barrier  40  define third compartment  70 , wherein third barrier  72  is located more proximal to outlet wall  18  than second barrier  40 . Third barrier  72  preferably extend between first side wall  20  and second side wall  22 . In addition, top  24  and bottom  26  rest upon third barrier  72  and help define third compartment  70 . Third barrier  72  is preferably made of a plurality of divergently tapering planar surfaces  74  oriented in substantially vertical planes and connected at an apex  76  positioned at substantially the center of the respective pulse stream of exhaust gases discharged from second compartment  40 . The planar surfaces  74  are also connected at a base  78  thereof wherein the most distal planar surfaces  74  are connected to first side wall  20  and second side wall  22  respectively. The planar surfaces  74  are arranged to form substantially V-shaped walls that are interconnected such that the base  78  of the planar surfaces are proximal to second barrier  40  and the apex  76  is distal thereto.  
         [0030]    The three exhaust pulse streams denoted by arrows  54 ,  58 , and  62  emanate from holes  46 ,  44 , and  48  respectively into third compartment  70 . As a result of the arrangement of the planar surfaces  74 , the exhaust pulse streams are directed to the apexes  76  of the third barrier  72 . At each apex  76  of the third barrier  72  a cavity  80  is defined therein. Each cavity  80  may be of the same sized opening, but in a preferred embodiment, the cavity  80  located on the central apex  76  is substantially twice as large as each of the cavities  80  located on the laterally located apexes  76 , such that the central cavity  80  is equivalent to the sum of the laterally located cavities  80 .  
         [0031]    The three exhaust pulse streams denoted by arrows  54 ,  58  and  62  travel through the third compartment  70  and out of the cavities  80  located on apexes  76  into a fourth compartment  82 . A fourth barrier  84  extends between first side wall  20  and second side wall  22  and also extends between top  24  and bottom  26  to form the fourth compartment  82  in cooperation with third barrier  72 . Fourth barrier  84  is substantially concave and therefore has a peak  86  formed by the attachment of fourth planar surfaces  88 . Peak  86  is more distal to third barrier  72  than the point of attachment of the fourth planar surfaces  88  to first and second side walls  20  and  22 . As such, the three pulse streams  54 ,  58  and  62  within the fourth compartment are recombined at a point proximal to the peak  86  as denoted by arrow  90 . An orifice  92  is defined on fourth barrier  84  at peak  86  such that the united exhaust pulse stream  90  travels there through and is led to a second opening  94  defined on outlet wall  18 . The pulse stream  90  travels out of the second opening  94 , through outlet conduit  14  and into the atmosphere. However, it is to be understood that orifice  92  may be made of any other shape, such as circular, and the size of the orifice  92  may be modified in accordance with the size of the muffler device  10 .  
         [0032]    For purposes of illustration and not limitation, muffler device  10  having one preferred dimension will be set forth herein. It will be understood that modifications may be made to the same without departing from the essence of the invention. Device  10  may have an inlet and outlet conduit  12  and  14  having a diameter of 2.25 inches. Accordingly, the walls  16 ,  18 ,  20 , and  22  have a height of 4 inches. The device  10  has a length and width of 13 inches and 9 inches, respectively. First aperture  36  has a diameter 2.25 inches and the first hole  44  has a diameter of 2 inches. Second aperture  38 , second hole  46 , and third hole  48  each have a diameter of approximately on inch. Central cavity  80  located on central apex  76  has substantially equal sides of 2 inches and the lateral cavities  80  each have equal sides of 1 inch defining the same. The orifice  92 , in a preferred embodiment, is substantially square shaped with each side measuring approximately 2.25 inches. Now referring specifically to FIG. 7, in an alternate preferred embodiment, the fourth barrier  84  may be eliminated such that the three pulse streams indicated by arrows  54 ,  58 , and  62  converge to form pulse stream  90  as a result of the expulsion of the exhaust stream through second opening  94 .  
         [0033]    The illustrated muffler device  10  was mounted onto a 1965 Ford Mustang automobile having a V8, 2.89 liter engine and the horse power produced by the attachment of the device  10  was measured by the Clayton 400 h.p. machine. The device  10 , when attached to the vehicle, produced 120 horse power at 4500 rpm, at 90 miles per hour. The same vehicle was then used to test the three chamber Flowmaster muffler sold as part #42553 by Flowmaster, Inc., Santa Rosa, Calif. The Flowmaster muffler, when attached to the vehicle, produced 110 horse power at 4500 rpm, at 90 miles per hour. In addition, when a flow rate test was conducted to measure the back pressure between the device  10  and the Flowmaster muffler at  28 ″ column of mercury test pressure, they both had an equal Cubic Feet per Minute (CFM) test result of 216.  
         [0034]    In addition, while a sound spectrum analyzer was not available for use in analyzing the frequencies which produced the overall relative loudness of the tested devices, subjective observation of the sound indicated that the muffler device  10  of the instant invention had a much more pleasing combination of resultant sound frequencies as compared to the muffler obtained from Flowmaster. Although quantitative measurements are not possible without a sound spectrum analyzer, it was clear from subjective or qualitative listening by observers that the frequency spectrum of sound emitted from the device  10  could be varied by positioning intermediate the barriers  32 ,  40 ,  72 , and  84  closer or farther away from inlet wall  16 . It is believed that the shape and location of the barriers  32 ,  40 ,  72  and  84  can be varied to tune the muffler to attenuate undesirable sound frequencies and permit more acceptable frequencies, all without substantially increasing, and in fact decreasing, the muffler back pressure.  
         [0035]    It is hypothesized that several phenomena account for the performance enhancement produced by the muffler device  10 . First, the sound components entering device  10  are initially relatively entrained in and coaxial with the entering exhaust gases. As they impinge upon first barrier  32 , however, they become reflected from the first barrier  32  and increasingly diverge from or become transverse to the flow of the exhaust gases. As the exhaust gases move first compartment  34 , it is believed that a substantial number of sound components will be reflected. Thus, sound components reverberate back and forth between interior surfaces defined by within first compartment  34  and tend to cancel or attenuate each other out.  
         [0036]    It is further hypothesized that the reduction in back pressure in the muffler device  10  could be the result of any one of three possible sources. First, it will be seen, especially in FIG. 5, that exhaust gas flow must partition immediately in order to proceed the second compartment  42 . The exhaust stream indicated by arrow  58  is immediately once again partitioned in second compartment  42 . Upon entry into the third compartment  70 , three exhaust streams are created which are then rejoined in fourth compartment  82 . Accordingly, as a result of the redirection of the exhaust streams, a lower back pressure may be achieved.  
         [0037]    A second phenomena which may be occurring is that, as exhaust gases pass from first compartment  34  to second compartment  42 , there may be venturi effect with respect to the volume thereof in the second compartment  42  that lowers the pressure therein. This lower pressure has a scavenging effect which causes the muffler back pressure to be relatively low. However, the lower pressure of the second compartment does not result in a build-up of unignited fuel because live fire from the first compartment  34  may easily be transmitted to the second compartment because of the design of first conduit  50 .  
         [0038]    Finally, the addition sound attenuation or cancellation produced may be causing a pressure drop.  
         [0039]    While the above description contains many specificities, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of preferred embodiments thereof. Many other variations are possible without departing from the essential spirit of this invention. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.