Patent Publication Number: US-7905321-B2

Title: Inserts for engine exhaust systems

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of application Ser. No. 11/705,099, entitled “Inserts for Engine Exhaust Systems”, filed Feb. 12, 2007, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to exhaust systems for internal combustion engines. More specifically, the present invention relates to inserts for engine exhaust systems for reducing or otherwise baffling or modifying the sound of the exhaust when the engine is in operation. The inserts may also serve as spark arrestors as well. 
     2. Description of the Related Art 
     While virtually all automobiles and trucks come equipped at the time of purchase with adequate sound suppression systems for their engines, this is not necessarily the case with many vehicles intended for off-road use. Personal watercraft and various racing and competition vehicles, wheeled or otherwise, may have relatively loud engine exhaust systems in order to reduce restrictive back pressure in the exhaust. In other cases, vehicle owners have modified the exhaust systems of their automobiles, motorcycles, etc. in an attempt to provide a distinctive sound, or perhaps a distinctive appearance for the exhaust system where it is exposed, as is the case with motorcycles. 
     Perhaps the easiest way of reducing the back pressure in an exhaust system is to construct a system wherein all of the pipes are completely open, i.e., without internal restriction. Many motorcycle owners and operators have attempted operation with such open exhaust systems, and in fact, the sound output of such systems may be legal and/or acceptable in some conditions, particularly with smaller engines and where the type of vehicle is not heavily regulated insofar as its exhaust emissions (sound and otherwise) are concerned. 
     While this may be acceptable in some circumstances, the resulting noise level is certainly not acceptable in most operating environments. One problem with such modification is that the resulting modified exhaust system may produce a sound level that exceeds the maximum permitted by law for the jurisdiction and/or type of vehicle. This may be true of racing, competition, and off road vehicles as well, depending upon the environment of use, rules of the sanctioning body, and perhaps other factors. When this occurs, the owner or operator of the vehicle must find some way to reduce the sound output of the exhaust system. 
     Various techniques have been developed in the past for reducing the sound level output of an internal combustion engine exhaust system, e.g., stuffing steel wool and/or glass fiber packing into the pipe or tube, etc. Such a modification is easily accomplished, but the resulting back pressure in the system is likely excessive. Other than the above well-known technique, the present inventor is only aware of exhaust systems and components (replacement mufflers, etc.) that incorporate rigid internal baffling installed at the time of manufacture. The end user cannot easily modify such an exhaust system by removing and/or replacing one or more inserts therein to affect the sound output of the exhaust system. 
     An example of such a manufactured exhaust system is disclosed in Japanese Patent No. 6-323,136 published on Nov. 22, 1994. This reference describes (according to the drawings and English abstract) an internal supporting structure for a concentrically installed rigid tube and catalytic converter assembly within an outer exhaust pipe. The assembly is permanently installed within the outer pipe at the time of manufacture of the device, with no means provided for inserting the internal assembly within an existing pipe having a closed wall, particularly in the case of a curved pipe. 
     None of the above inventions and patents, taken either singly or in combination, is seen to describe the instant invention as claimed. Thus, inserts for engine exhaust systems solving the aforementioned problems is desired. 
     SUMMARY OF THE INVENTION 
     The inserts for engine exhaust systems comprise various embodiments of a flexible conical mesh or screen formed of fibers (e.g., metal, ceramic, glass fiber, etc.) or rovings of metal bands that are interlaced (e.g. 304 stainless steel) capable of resisting high temperatures. Each conical insert is provided with a rigid circumferential attachment ring at its larger diameter end, with the ring having an outer diameter closely conforming to the inner diameter of the pipe. The inserts may comprise a single frustoconical unit with the smaller diameter end being supported by a rigid ring, which is, in turn, braced within the pipe, or which has an unsupported smaller diameter end. Alternatively, the insert may comprise a pair of opposed frustoconical units having opposed larger diameter ends and joined smaller diameter ends. The attachment and/or support rings may be welded to the metal mesh material of the conical component, or each may comprise a pair of concentric rings crimped together with the mesh captured therebetween. A coiled spring may be installed within the flexible conical mesh to provide some additional rigidity, and/or additional baffling may be provided in the form of a relatively thin glass fiber batt installed over the outer surface of the mesh. 
     Each of the various embodiments may be installed within an existing open exhaust pipe, i.e., one not having any internal sound reducing structure therein, by sliding the attachment or support ring into the interior of the pipe and using a flexible tool to work the insert into the pipe to the location desired. The flexibility of the conical mesh portion allows the insert to bend and flex to pass through curved or bent areas of the exhaust pipe without jamming therein. The flexibility of the insert, as well as its sound deadening capacity, can be enhanced by forming the peripheral surface into a bellows-type configuration (VVVVVV). Any practicable number of such inserts, in any practicable configuration, may be installed within a single pipe. When the device is located, it may be anchored in place by securing a screw, rivet, etc. through the wall of the pipe and through the attachment ring of the device within the pipe. The screw may be removed and/or the rivet drilled out for removal of the device at a later date. Alternatively, the device may be permanently installed within the pipe, e.g., by spot welding the attachment ring in place within the pipe. The installed device serves to reduce the exhaust sound emissions of the engine exhaust, and may also serve as a spark arrestor as well. 
     These and other features of the present invention will become readily apparent upon further review of the following specification and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view of a first embodiment of an insert for an engine exhaust system according to the present invention. 
         FIG. 2  is a side elevation view in section of the insert embodiment of  FIG. 1 , the external wrap being omitted. 
         FIG. 3  is a broken away perspective view of a sinusoidal exhaust pipe having a second embodiment of an insert for an engine exhaust system according to the present invention installed therein, showing various details of the insert and its installation. 
         FIG. 4  is a broken away side elevation view of a sinusoidal exhaust pipe having a plurality of different embodiments of inserts for an engine exhaust system according to the present invention installed therein. 
         FIG. 5  is a broken away perspective view of a sinusoidal exhaust pipe having a third embodiment of an insert for an engine exhaust system according to the present invention installed therein, showing various details of the insert and its installation. 
         FIG. 6  is a broken away perspective view of a sinusoidal exhaust pipe having a fourth embodiment of an insert for an engine exhaust system according to the present invention installed therein, showing various details of the insert and its installation. 
     
    
    
     Similar reference characters denote corresponding features consistently throughout the attached drawings. 
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention comprises an insert for the engine exhaust system of an internal combustion engine, e.g., automobile, truck, motorcycle, boat, personal watercraft, aircraft, stationary generator engine, etc. All such engines include an exhaust system in the form of one or more pipes extending from the exhaust ports of the cylinder head to transfer exhaust gas output to a region clear of the engine and/or vehicle. In many instances, particularly (but not exclusively) in the case of vehicles operated off-road, regulations regarding exhaust system sound level output are relatively loose or even non-existent. In other cases, the owner or operator of the vehicle may wish to install a different type of exhaust system, and must accommodate regulations regarding sound output of the system. 
       FIG. 1  of the drawings provides an exploded perspective view of a first embodiment of an insert for an engine exhaust system, designated generally as  10 , with  FIG. 2  providing a side elevation view in partial section of the insert  10  of  FIG. 1  without the optional external fiber batt covering shown in  FIG. 1 . The exhaust insert  10  of  FIGS. 1 and 2  includes a frustoconical mesh component  12  formed of a woven, high temperature resistant material, e.g., corrosion resistant steel (i.e., “stainless” steel), glass or ceramic fiber, etc. Alternatively, a standard steel or other metal may be used, if desired. The material selected for the mesh component should provide sufficient porosity and flow-through to allow exhaust gases to pass therethrough without significant back pressure, and should be sufficiently flexible to allow for installation in a curved pipe by passing the insert  10  through the pipe and any curved portions thereof. A stainless steel braided mesh has been found to work well in testing, but other materials may be used in lieu thereof, as described above. 
     The frustoconical mesh component  12  includes a large diameter first end  14  and an opposite second end  16  of smaller diameter than the first end. The two diameters  14  and  16  are selected so that the larger diameter end  14  fits closely within the internal diameter of the exhaust pipe, as shown in  FIGS. 3 and 4  and discussed further below, with the smaller diameter end  16  being formed with a diameter small enough to develop the desired level of sound restriction in the exhaust output. 
     The larger diameter end  14  of the frustoconical mesh component  12  should retain its open shape to conform closely to the internal diameter of the exhaust pipe in order to avoid significant bypass of exhaust past the outer edge or surface of the mesh. This is accomplished by means of an attachment ring component secured to or about the larger diameter end  14  of the mesh component. In the embodiment  10  of  FIGS. 1 and 2 , the attachment ring component comprises concentric outer and inner attachment rings  18  and  20 , which capture the larger diameter end  14  of the mesh component  12  therebetween. The larger diameter outer attachment ring  18  has an outer diameter  22  configured to fit closely within the inner diameter of the exhaust pipe in which the device is to be installed, and an inner diameter  24  configured to fit about the open end  14  of the mesh component  12 . The inner attachment ring  20  has an outer diameter  26  configured to fit closely within the open end  14  of the mesh component  12 , with the inner diameter of the inner ring  20  being of sufficient size to avoid undue restriction of exhaust gases passing therethrough. The inner attachment ring  20  is first installed within the larger diameter end  14  of the mesh component  12 , with the outer attachment ring  18  being placed concentrically thereover. The opposite edges of the outer ring  18  are then secured about the corresponding edges of the inner ring  20 , and the mesh material  12  is sandwiched therebetween by crimps  28 , as shown in  FIG. 2 . 
     The exhaust system insert  10  of  FIGS. 1 and 2  also includes a support ring component at the smaller diameter end  16  thereof. The small diameter end support ring component assembly is similar to the large diameter support ring component assembly discussed above, having concentric outer and inner attachment rings  30  and  32 , which capture the smaller diameter end  16  of the mesh component  12  therebetween. The outer attachment ring  30  should not define an unduly large thickness. The small diameter end outer attachment ring  30  may have radially disposed brace arms  34  extending therefrom, with the lengths of the arms  34  being dimensioned to have a span or diameter  36  (shown in  FIG. 2 ) to fit closely within the inner diameter of the exhaust pipe within which the device  10  is to be installed. These brace arms  34  thus hold the small diameter end support ring component or assembly concentrically within the exhaust pipe. The inner diameter  38  of the small end outer ring  30  is configured to fit about the smaller diameter end  16  of the mesh component  12 . The inner attachment ring  32  of the small diameter end has an outer diameter  40  configured to fit closely within the smaller diameter end of the mesh component. The inner attachment ring  32  is first installed within the smaller diameter end  14  of the mesh component, with the outer attachment ring  30  being placed concentrically thereover. The opposite edges of the outer ring  30  are then secured about the corresponding edges of the inner ring  32 , and the mesh material  12  is sandwiched therebetween by crimps  42 , as shown in  FIG. 2 . 
     Additional support may be provided for the exhaust insert  10  by installing a spring  44  therein, if desired, generally as shown in  FIGS. 1 and 2 . The spring  44  preferably comprises a tapered coil spring, i.e., having a frustoconical external shape, dimensioned to fit closely within the frustoconical shape of the mesh component  12  and having opposite large and small diameter ends closely matching the large and small diameter ring components at each end of the mesh component. The spring  44  provides additional support for the mesh component  12 , holding it in its desired conical configuration. The spring  44  is preferably formed of a corrosion resistant steel, but other materials may be used as desired. 
       FIG. 1  also illustrates an additional optional glass fiber batt  46 , which may be installed about the exterior of the frustoconical mesh  12 , if desired. The batt  46  is formed of material similar to that used in thermal insulation, but is considerably thinner (e.g., one-half inch, more or less) in order to fit within the exhaust system. The batt  46  is cut to conform to the frustoconical shape of the exterior of the mesh  12 , and is secured in place by wrapping, sewing, or otherwise attaching a steel wire strand  48  (or other material having sufficient heat resistant properties) about the batt  46  to secure it to the underlying mesh  12  material. It will be seen that the exhaust insert  10  of  FIG. 2  is identical to that of  FIG. 1 , except for the optional batt shown in  FIG. 1 . 
       FIG. 3  of the drawings provides an illustration of a second embodiment of an exhaust system insert, designated generally as  110  in the drawings. The insert  110  of  FIG. 3  comprises a longitudinally symmetrical device having opposed mirror image portions. The insert  110  includes first and second frustoconical sections  112   a  and  112   b , respectively, which are formed of any suitable porous mesh material (e.g., stainless or standard steel screen or mesh, glass fiber, ceramic mesh, etc.). Each section  112   a  and  112   b  includes a large diameter first end  114   a  and  114   b  and an opposite second end  116  of smaller diameter than the first end. It will be seen that the two frustoconical sections  112   a  and  112   b  of the mesh component form a continuous length extending between their opposite ends  114   a  and  114   b , with the smaller diameter end  116  of each portion  112   a  and  112   b  being common between the two portions  112   a  and  112   b . The two large diameter ends  114   a  and  114   b  are selected so that their outer diameters fit closely within the internal diameter ID of the exhaust pipe P, as shown in  FIGS. 3 and 4 . 
     The exhaust insert  110  of  FIG. 3  includes substantially identical first and second attachment ring components  118   a  and  118   b  permanently secured to the respective ends  114   a  and  114   b  of the mesh portions  112   a  and  112   b  of the device. These attachment ring components  118   a  and  118   b  may comprise two concentric rings capturing the end of the mesh component  112   a  and  112   b  therebetween, as in the ring assemblies  18  and  20  of the embodiment  10  of  FIG. 1 , or may alternatively comprise single rings attached to the mesh by weldments  119  when a metal material is used to form the mesh portion of the insert  110 . Conversely, the ring components of the embodiment  10  of  FIG. 1  may comprise single rings of appropriate diameter at each end of the mesh and welded thereto, if so desired. However, installation of support rings comprising two concentric rings capturing the mesh material therebetween is preferred, as the welding of the fine strands of the mesh to the support ring is a tedious and time consuming operation. In any event, the outer diameters  122   a  and  122   b  of the two rings or ring assemblies  118   a  and  118   b  are dimensioned to fit closely within the internal diameter ID of the pipe P, as shown in  FIGS. 3 and 4  of the drawings. 
     The exhaust system insert  110  of  FIG. 3  (and other embodiments of the device) is secured within the exhaust pipe P by appropriate fasteners, e.g., a screw or screws  150  driven through concentric attachment passages in the outer wall of the exhaust pipe P and the corresponding attachment ring, e.g., the first ring  118   a , or a rivet  152  installed in concentric attachment passages, as shown for the second ring  118   b  of  FIG. 3 . Preferably, “blind” rivets are used, i.e., rivets that are set solely by the use of an external tool applied to the manufactured head. Thus, the insert  110  (and others installed in a similar manner) may be removed if so desired, by removing the screw(s)  150  and/or drilling out the rivet(s)  152 . Alternatively, the exhaust insert  110  (and others) may be permanently installed within the pipe P by spot welding the attachment rings  118   a ,  118   b  (or others) through the wall of the pipe P. 
       FIG. 4  of the drawings provides a cross-sectional view of an exemplary installation of various different embodiments of the exhaust system insert in a single exhaust pipe P. A person installing the insert, or inserts, may not wish to install one of each of the embodiments shown in  FIG. 4  within a single pipe P. However,  FIG. 4  provides an illustration of the installation of each type or embodiment of the insert in a single drawing for convenience in illustration. The inserts  10  and  110 , shown respectively in the approximate center and toward the right end of the pipe P in  FIG. 4 , have been discussed in detail further above. However,  FIG. 4  also illustrates a third embodiment of the insert, designated as insert  210 . The insert  210  is configured much like the insert  10  of  FIGS. 1 and 2 , having a single frustoconical portion  212  of flexible porous mesh material with a large diameter end  214  and an opposite smaller diameter end  216 . As in the case of the other exhaust system inserts  10  and  110  discussed further above, the attachment ring  218  of the insert  210  has an outer diameter  222  closely fitting within the internal diameter ID of the exhaust pipe P in order to preclude significant exhaust flow between the outer surface of the ring  218  and the inner surface of the pipe P. The attachment ring component  218  of the embodiment  210  of  FIG. 4  preferably comprises a pair of concentric rings capturing the larger diameter end  214  of the mesh  212  therebetween, as in the ring assembly  18  and  20  of the embodiment  10  of  FIGS. 1 and 2 , or may alternatively comprise a single ring with the metal mesh  212  welded thereto, as in the embodiment  110  of  FIG. 3 . 
     The exhaust system insert  210  of  FIG. 4  differs from the insert  10  of  FIGS. 1 ,  2 , and  3  in that the insert  210  does not have any form of support ring at its smaller diameter end  216 . Thus, the smaller diameter end  216  is free to “float” within the interior of the pipe P. It will be noted that the exhaust flow in such an installation is from right to left through the pipe P, as indicated by the exhaust flow arrows F in  FIG. 3 . Thus, the inlet end of the insert  210  is anchored within the pipe P by the larger diameter attachment ring  218 , while the smaller diameter outlet end  216  is free to blow downstream in the exhaust system, somewhat in the manner of an aviation windsock used to indicate the direction of the wind at airports. However, it will be noted that the other embodiments  10  and  210  may be installed without concern for the direction of exhaust gas flow through the pipe P, as each of their ends are anchored or braced within the pipe. 
     The exhaust insert  110 ′ of  FIG. 5  includes substantially identical structure as shown in  FIG. 3 , with like structure being indicated by a “prime”. As seen in  FIG. 5 , the exhaust insert  110 ′ includes substantially identical first and second attachment ring components  118   a ′ and  118   b ′ permanently secured to their respective ends  114   a ′ and  114   b′  of the interlaced flat roving portions  112   a ′ and  112   b ′ of the device. These attachment ring components  118   a ′ and  118   b ′ may comprise two concentric rings capturing the end of the roving component  112   a ′ and  112   b ′ therebetween, as in the ring assemblies  18  and  20  of the embodiment  10  of  FIG. 1 , or may alternatively comprise single rings attached to the rovings by weldments  119 ′ when a metal material is used to form the roving portion of the insert  110 ′. However, installation of support rings comprising two concentric rings capturing the roving material therebetween is preferred, as the welding of the rovings to the support ring is a tedious and time consuming operation. In any event, the outer diameters  122   a ′ and  122   b ′ of the two rings or ring assemblies  118   a ′ and  118   b ′ are dimensioned to fit closely within the internal diameter ID of the pipe P, as shown in  FIGS. 3 ,  4 , and  5  of the drawings. 
     The exhaust system insert  110 ′ of  FIG. 5  (and other embodiments of the device) is secured within the exhaust pipe P′ by appropriate fasteners, e.g., a screw or screws  150 ′ driven through concentric attachment passages in the outer wall of the exhaust pipe P′ and the corresponding attachment ring, e.g., the first ring  118   a ′, or a rivet  152 ′ installed in concentric attachment passages, as shown for the second ring  118   b ′ of  FIG. 5 . Preferably, “blind” rivets are used, i.e., rivets that are set solely by the use of an external tool applied to the manufactured head. Thus, the insert  110 ′ (and others installed in a similar manner) may be removed, if so desired, by removing the screw(s)  150 ′ and/or drilling out the rivet(s)  152 ′. Alternatively, the exhaust insert  110 ′ (and others) may be permanently installed within the pipe P′ by spot welding the attachment rings  118   a ′,  118   b ′ (or others) through the wall of the pipe P′. 
     As depicted in  FIG. 5 , the exhaust insert  110 ′ is constituted by a tubular braid or interlacing of bundles of filaments, wires, or multifilament strands or ribbons of metal, for example, 304 stainless steel. The rovings in this embodiment are composed of an interlacement of flat rovings helically wound about the axis of the insert, wherein each flat roving comprises in a combined manner a plurality of strands, each strand having multiple filaments side-by-side. The number of bundles or flat rovings depends on the process or braiding machine used. In addition, the number of wires in each flat roving, the diameter and strength of the wires, as well as the braid angle or angle of interlacement are chosen as a function of the final performance characteristics expected of the insert. 
     The rovings form a continuous outer surface from the large diameters  114   a ′ and  114   b ′ through the smaller diameters  116 ′. Additionally, the interlacing of the rovings is designed to leave spaces or pores  155  therebetween in order to ensure that the exhaust insert has the requisite flexibility and bending ability to conform to the configuration of the exhaust pipe P′. The spaces also ensure that the exhaust gases can “breathe” or escape therethrough. Although the rovings are depicted as wires or strands, it is recognized that the interlacing bands may be metal tapes or combinations of filamentary rovings and metal tapes. Although  FIG. 5  depicts the outer surface of the exhaust baffle as a continuous surface, it is recognized that the outer surface could be configured in a bellows-type arrangement  157 . This type of peripheral configuration is shown in  FIG. 6 , wherein all other components are identical to that shown in  FIGS. 3 and 5 . 
     In conclusion, the insert for an engine exhaust system in its various embodiments provides a relatively simple and straightforward means for a person to reduce the sound emissions of an open exhaust system, i.e., an exhaust system not having any internal sound baffling or other internal components. The insert may also serve as a spark arrestor where such devices are required, regardless of any reduction of sound output provided by the device(s). 
     The insert is particularly well suited for installation in a motorcycle exhaust system, where the exhaust pipes curve or bend downwardly and rearwardly from the cylinder heads of the engine. The insert, with its flexible mesh or roving components, can be inserted into such an open pipe with a suitable tool and pass around curves and bends in the pipe for securing therein. While the insert is particularly well suited for installation in a motorcycle exhaust system, it should be noted that they are not limited to installation within such an exhaust system, but may be adapted to virtually any type of internal combustion engine exhaust system. Accordingly, the insert will be greatly appreciated by those who have occasion to construct custom exhaust systems, and/or modify exhaust systems to produce a required or desired level of sound output. 
     It is to be understood that the present invention is not limited to the embodiments described above, but encompasses any and all embodiments within the scope of the following claims.