Abstract:
An exhaust silencer includes a flow pipe supported in a housing. A space is defined between the flow pipe and the housing. At least one movable flap is located in the space and is resiliently biased to a closed position and movable by exhaust gas pressure from said closed position to an opened position. The at least one flap provides less restriction to exhaust gas flow through the space in the opened position as compared to the closed position. The one or more flaps are pivotably supported on a spring-biased hinge assembly or are provided as part of a resiliently deformable baffle plate that uncovers flow apertures under force of exhaust pressure. The baffle plate is selectively removable by an end-user to allow for maximum exhaust flow when desired. The flow pipe can be omitted in a base plate only version.

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
       [0001]     This application claims priority from and benefit of the filing date of U.S. provisional application Ser. No. 60/724,460 filed Oct. 7, 2005, and said provisional application is hereby incorporated by reference into the present specification. 
     
    
     BACKGROUND  
       [0002]     Silencers for automobile exhaust systems are known. One type of silencer is known as an active silencer due to its capacity to adjust in response to pressure of exhaust gases in the system. As such, at low engine revolutions per minute (RPM) with correspondingly low exhaust pressure, the silencer remains substantially closed to increase exhaust backpressure and reduce noise, while increase in engine RPM causes a corresponding increase in exhaust gas pressure which, in turn, is used to open the silencer against the closing force of a biasing spring to reduce backpressure which causes an increase in exhaust noise and engine power. While known active silencers are superior to passive silencers, which merely restrict exhaust flow by constant amount, known active silencers have also been deemed deficient for complexity, cost, insufficient backpressure reduction when opened, reliability and other reasons. As such, a need has been identified for a new and improved active exhaust silencer.  
       SUMMARY  
       [0003]     In accordance with one aspect of the present invention, an exhaust silencer includes a housing and a flow pipe supported in the housing. A space defined between the flow pipe and the housing. At least one movable flap is located in the space and is resiliently biased to a closed position and movable by exhaust gas pressure from the closed position to an opened position. The flap provides less restriction to exhaust gas flow through the space in the opened position as compared to the closed position.  
         [0004]     In accordance with another aspect of the present invention, and exhaust silencer includes a housing and a base plate secured in the housing. The base plate defines at least one main flow opening and at least one secondary flow opening. At least one flexible metal baffle is secured to the base plate and is normally resiliently biased to a closed position where it covers the secondary flow aperture. The baffle is resiliently movable by exhaust gas pressure from its closed position to an opened position where it moves away from the secondary flow opening(s) to allow exhaust gas flow therethrough. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0005]      FIG. 1  is a cross-sectional view of an exhaust silencer formed in accordance with the present development;  
         [0006]      FIG. 2  is an end view of the exhaust silencer taken along view line  2 - 2  of  FIG. 1  and shows the silencer in its closed state (note that in  FIG. 2 , the exhaust silencer is not sectioned as in  FIG. 1 );  
         [0007]      FIG. 3  is an end view that corresponds to  FIG. 2 , but shows the exhaust silencer in its opened state;  
         [0008]      FIG. 4  is an end view similar to  FIG. 2 , but shows an exhaust silencer formed in accordance with an alternative embodiment (a portion of the baffle is broken away to reveal an underlying baffle base plate);  
         [0009]      FIG. 5  is a sectional view of the exhaust silencer of  FIG. 4 , as taken along line  5 - 5  of  FIG. 4 ;  
         [0010]      FIG. 6  is a sectional view that is similar to  FIG. 5 , but shows an alternative embodiment of an exhaust silencer formed in accordance with the present development.  
         [0011]      FIG. 7  is a sectional view that is similar to  FIG. 6 , but shows another alternative embodiment of an exhaust silencer formed in accordance with the present development.  
     
    
     DETAILED DESCRIPTION  
       [0012]      FIGS. 1-3  illustrate an exhaust silencer ES formed in accordance with a first embodiment of the present development for use in silencing/tuning the exhaust of an internal combustion engine such as used to propel a vehicle such as an automobile, boat, etc. or for some other purpose.  
         [0013]     As illustrated herein, the silencer ES is intended to be retro-fitted into an existing exhaust tailpipe T using one or more fasteners F 1  such as a bolt, rivet, screw, etc., or by other means such as welding, friction-fit or the like to secure the silencer to the tailpipe T. In particular, the exhaust silencer ES comprises an outer housing tube H that is fitted into the tailpipe T, and the fasteners F 1  or other means are used to fixedly secure the housing tube H relative to the tailpipe T. If necessary and/or desired, a spacer or gasket K can be used to surround the housing tube H to fill any space defined between the tailpipe T and housing tube H. In some cases, such as when the silencer ES is supplied as original equipment, the tailpipe T, itself, provides the housing tube H, and the fasteners F 1  are not needed.  
         [0014]     At least one open flow pipe P is located, preferably concentrically, in the housing tube H and secured therein by rivets, bolts, screws and/or other fasteners F 2  ( FIG. 1 ) that engage the housing tube H and open flow pipe P. This open flow pipe P has an upstream end P 1  and a downstream end P 2  and allows free-flow of exhaust gases therethrough from the upstream end P 1  to the downstream end P 2  so that exhaust gases can flow from an upstream position in the tailpipe T toward the outlet O of the tailpipe T as indicated by arrow A 1  in  FIG. 1 .  
         [0015]     An annular space B is defined between the pipe P and the housing H. First and second flow-control flaps C 1 ,C 2  are located in the annular space B, near an outer end thereof. These flaps C 1 ,C 2  move between a closed position ( FIGS. 1 and 2 ) where they are arranged at a 180 degree angle relative to each other or are otherwise arranged to substantially block the flow of exhaust gases through the annular space B from an upstream location in the tailpipe T to the tailpipe outlet O (see arrows A 2 ), and an opened position ( FIG. 3  and phantom lines of  FIG. 1 ) where they define an included angle Θ of less than 180 degree or are otherwise arranged so as to allow flow of exhaust gases through the annular space B from an upstream location in the tailpipe T to the tailpipe outlet O (see arrows A 3 ). The flaps C 1 ,C 2  are located near the downstream/outer end P 2  of the pipe P so that the pipe P does not interfere with pivoting movement of the flaps C 1 ,C 2 .  
         [0016]     As is easily seen in  FIG. 3 , the flow-control flaps C 1 ,C 2  are pivotally connected to the housing tube H and the open flow pipe P. In particular, first and second hinges G 1 ,G 2  defined by pins or the like and extend between the housing tube and pipe P in diametrically opposed locations, and the flaps C 1 ,C 2  are each pivotally connected to both hinges G 1 ,G 2 . At least one of the hinges G 1 ,G 2  comprises a torsion spring N or the like that includes feet N 1 ,N 2  that are engaged respectively with the flaps C 1 ,C 2  to bias the flaps C 1 ,C 2  to their closed positions ( FIG. 2 ) where they obstruct the flow of exhaust gases through the annular space B (as shown, each hinge G 1 ,G 2  comprises a separate spring N). The spring(s) N is (are) selected so that the flaps C 1 ,C 2  are able to pivot against the spring(s) N as shown by arrows A 4  when the exhaust gas pressure in the annular space B exceeds a select threshold, which will vary depending upon the desired performance characteristics and the particular vehicle or other application. In one embodiment, the flaps are intended to stay closed during idle of an automobile, to open slightly (i.e., move 10 degrees or so from vertical) during normal vehicle acceleration, and open substantially (i.e., move at least 30 degrees from vertical) during hard acceleration.  
         [0017]     When the exhaust gas pressure in the annular space B subsides, the springs N 1 ,N 2  return the flaps C 1 ,C 2  toward and/or fully to their closed positions. Stops M 1 ,M 2  are provided and engage the flaps C 1 ,C 2 , respectively, when the flaps are closed to prevent movement of the flaps C 1 ,C 2  beyond their closed positions under force of springs N 1 ,N 2 . As shown, the stops M 1 ,M 2  are defined by indented portions of the housing tube H, but can be defined by rivets, tabs, screws or other suitable fixed member that extends into the annular space B.  
         [0018]     Those of ordinary skill in the art will recognize that when the flaps C 1 ,C 2  are closed, exhaust gas flow and noise are restricted owing to the fact that the only path for the exhaust gases to flow to the tailpipe outlet O is via pipe P (except for any leakage around flaps C 1 ,C 2 ). When the flaps C 1 ,C 2  open under exhaust pressure, the exhaust gas flow and engine performance and noise increase, because the exhaust gases are able to flow to the tailpipe outlet O through the pipe P and also through the annular space B. As such, the exhaust silencer ES provides a self-adjusting capability that is responsive to exhaust gas pressure that varies with driving habits or other causes of variations in exhaust gas pressure.  
         [0019]     Except for the optional gasket K, the components of the exhaust silencer are preferably defined from a metal such as steel or stainless steel using grades and alloys that are known in the exhaust arts. The springs N 1 ,N 2  are preferably metal and defined from suitable spring wire such as (by way of example only) stainless steel, Inconel, or other metal with sufficient resistance to elevated temperature creep and fatigue.  
         [0020]      FIGS. 4 and 5  illustrate an alternative exhaust silencer ES′ formed in accordance with the present development. The silencer ES′ is intended for the same application and use and to perform the same function as the silencer ES, but includes a different silencing mechanism. Components of the silencer ES′ that correspond to components of the silencer ES are labeled with reference characters that correspond to those used in  FIGS. 1-3 , but include a primed (′) suffix.  
         [0021]     The silencer ES′ is intended to be retro-fitted into an existing exhaust tailpipe T′ using one or more fasteners F 1 ′ such as a bolt, rivet, screw, etc., or by other means such as welding, friction-fit or the like that engage the tailpipe T′ and housing tube H′. In particular, the exhaust silencer ES′ comprises an outer housing tube H′ that is fitted into the tailpipe T′, and the fasteners F 1 ′ or other means are used to fixedly secure the housing tube H′ relative to the tailpipe T′. If necessary and/or desired, a gasket K′ can be used to surround the housing tube H′ to fill any space defined between the tailpipe T′ and housing tube H′. In some cases, such as when the silencer ES′ is supplied as original equipment, the tailpipe T′, itself, provides the housing tube H′, and the fasteners F 1 ′ are not needed.  
         [0022]     At least one open flow pipe P′ is located, preferably concentrically, in the housing tube H′. The pipe P′ is secured in this position by one or more rivets, bolts, screws and/or other fasteners F 2 ′ that engage the housing tube H′ and open flow pipe P′. This open flow pipe P′ has an open upstream end P 1 ′ and an open downstream end P 2 ′ so as to allow free-flow of exhaust gases therethrough from an upstream position in the tailpipe T′ toward the outlet O′ of the tailpipe T′ as indicated by arrow A 1 ′. An annular space B′ is defined between the flow pipe P′ and the housing tube H′.  
         [0023]     A baffle base plate D′ is closely fitted in the housing tube H′ and is secured in this position. As shown, the baffle base plate D′ includes an outer flange DF′ that is engaged by the fasteners F 1 ′ or welding or the like to secure the baffle base plate D′ in its operative position in the housing tube H′. The baffle base plate D′ also defines a central pipe-support aperture DA′ through which the open flow pipe P′ extends. An optional fastener F 3 ′ or a spot weld, or other means is used to secure the pipe P′ to the baffle base plate D′. The baffle base plate D′ defines one or more flow apertures DE′ that provide a path for exhaust gases to flow from an upstream location in the tailpipe T′, through the annular space B′ and through the base plate D′ to the tailpipe outlet O′.  
         [0024]     To regulate the flow of exhaust gases through the flow apertures DE′ of the base plate D′, at least one flexible baffle J′ is secured adjacent the downstream side of the base plate D′(facing tailpipe outlet O′). The baffle J′ is preferably defined by a flexible metal sheet that includes an opening JO′ through which the flow pipe P′ is loosely received. As shown, the baffle J′ is secured directly to the base plate D′ by one or more rivets, screws or other fasteners F 4 ′. In some cases, the fasteners F 4 ′ are preferably non-removable and in others, the fasteners F 4 ′ are screws or other removable fasteners that allow a user to change baffles J′ or add (by stacking) additional baffles J′ to control exhaust flow. As is shown in  FIG. 4  and in solid lines in  FIG. 5 , the baffle J′ has a natural flat shape when relaxed or in a free state so that the baffle J′ is in a closed position and covers the flow apertures DE′ of the base plate D′ and inhibit or substantially block flow of exhaust gases therethrough from the annular space B′ to the tailpipe outlet O′. The baffle J′ is flexible and bends under force of exhaust pressure in the annular space B′ to an opened position, as shown in broken lines in  FIG. 5  and as indicated by arrows A 5 ′ where the flow apertures DE′ are at least partially uncovered by flaps C 1 ′,C 2 ′ of the baffle J′ to allow flow of exhaust gases through the annular space B from an upstream location in the tailpipe T to the tailpipe outlet O (see broken arrows A 6 ′ in  FIG. 5 ). Those of ordinary skill in the art will recognize that the first and second flaps C 1 ′,C 2 ′ of the baffle J′ correspond to the flaps C 1 ,C 2  of the exhaust silencer ES illustrated in  FIGS. 1-3 . In the closed position, the flaps are arranged at an angle of 180 degrees relative to each other and, when opened, are moved inward toward each other against the natural bias of the baffle J′. As shown herein, the flaps C 1 ′,C 2 ′ are part of a one-piece baffle J′. Alternatively, the baffles C 1 ′,C 2 ′ can be part of separate baffles J′, each of which is secured to the base plate D′.  
         [0025]     The baffle J′ is selected so that it bends to the opened position to allow exhaust gas flow through the flow apertures DE′ when the exhaust gas pressure in the annular space B exceeds a select threshold, which will vary depending upon the desired performance characteristics and the particular vehicle or other application. In one embodiment, the baffle J′ is intended to stay closed during idle of an automobile, to open slightly and partially uncover the apertures DE′ during normal vehicle acceleration, and to open fully during hard acceleration to at least substantially uncover the apertures DE′. When the exhaust pressure in the annular space B′ subsides, the baffle J′ resiliently returns to its normally closed position, which is a relatively flattened (not necessarily completely flat) state relative to the opened position.  
         [0026]     Those of ordinary skill in the art will recognize that when the baffle J′ is closed, exhaust gas flow and noise are restricted owing to the fact that the only path for the exhaust gases to flow to the tailpipe outlet O′ is via open pipe P′ (except for some leakage around the baffle base plate D′ and/or leakage through flow apertures DE′). When the baffle J′ opens, the exhaust gas flow and engine performance and noise increase, because the exhaust gases are able to flow to the tailpipe outlet O′ through both the pipe P′ and also through the annular space B′ via apertures DE′. As such, the exhaust silencer ES′ provides a self-adjusting capability that is responsive to exhaust gas pressure that varies with driving habits or other causes of variations in exhaust gas pressure.  
         [0027]     Except for the optional gasket K, which can be a heat/fire resistant insulation material, components of the exhaust silencer ES′ are preferably defined from a metal such as steel or stainless steel using grades and alloys that are known in the exhaust arts. The baffle J′ is preferably defined from metal such as (by way of example only) stainless steel, Inconel, or other metal with sufficient resistance to elevated temperature creep and fatigue, having a thickness, e.g., in the range of 0.005 inches to 0.015 inches (the thickness is varied to control the exhaust pressure required to flex the baffle J′ to its opened position). If desired, the user can selectively remove the baffle ′ to allow full exhaust flow under all conditions by removing screws F 4 ′. Also, the baffle J′ can be changed by a user to control the opening pressure (by replacing a baffle J′ with another having different flexibility), and multiple baffles J′ (of same or varied thickness/flexibility) can be stacked against the base plate D′ if desired to increase the pressure required to open the flow apertures DF′.  
         [0028]      FIG. 6  is a sectional view that is similar to  FIG. 5 , but shows an alternative embodiment of an exhaust silencer  2 ES′ formed in accordance with the present development. The exhaust silencer  2 ES′ is identical to the silencer ES′ except as shown and/or described herein. Specifically, in the silencer  2 ES′, the base plate  2 D′ includes only a single flow aperture DE′. One or more baffles  2 J′ (two as shown in  FIG. 6 ) are stacked adjacent each other and secured to the base plate  2 D′ by on or more fasteners F 4 ′, preferably located as shown, on an opposite side of the flow pipe P′ relative to the flow aperture DE′, e.g., at a 180 degree angle relative to the center of the flow aperture DE′, or at least spaced sufficiently far from the aperture(s) DE′ so that the one or more baffles  2 J′ can flex away from the base plate  2 D′ as shown. Each baffle  23 ′ is identical to the baffle J′ disclosed above, except for the location of the fastener F 4 ′. The opening  2 JO′ of each baffle  2 J′ loosely accommodates the outer end P 2 ′ of the flow pipe P′ so that the baffles  2 J′ can move relative to the flow pipe as described and shown herein.  FIG. 6  shows the baffles  2 J′ in the flexed, opened position, spaced from flow aperture DE′ to allow exhaust flow through the flow aperture DE′ as indicated by arrow A 6 ′. When exhaust pressure in the space B′ subsides, the baffles  2 J′ will move naturally by their own resilient nature to a closed position where they cover the flow aperture DE′ to impede exhaust flow through the space B′, which closed position is a relatively flattened (not necessarily completely flat) state for the baffles  2 J′ relative to their opened position. Using one or more like baffles  2 J′, a user can adjust the exhaust pressure required to open/close the baffle(s)  2 J′, which is desirable to adjust for different horsepower engines, etc. Thus, for example, for a lower horsepower engine, the user can choose to use a single baffle  2 J′ that will more easily flex to the opened position, while two or more baffles  2 J′ can be used for a higher horsepower engine so that the baffles are more resistant to moving to the opened position, requiring more exhaust pressure in the space B′ to do so.  
         [0029]     In another alternative embodiment  3 ES′ as shown in  FIG. 7 , the flow pipe P′ of  FIGS. 4 and 5  or of  FIG. 6  is not used. The base plate aperture DA′ is left open to define a main opening for unrestricted exhaust flow A 1 ′ through the housing H′ to the tailpipe outlet O′, while the base plate flow aperture(s) DE′ provide a secondary opening for exhaust flow only when the baffle(s)  2 J′ (or J′) are flexed from the closed to the opened position by exhaust pressure as described herein. The opening  2 JO′ in the baffle(s)  2 J′ is registered with the base plate aperture DA′ so that the baffle(s)  2 J′ do not block exhaust flow therethrough (i.e., through the main opening) even when the baffle(s)  2 J′ are in the closed position.  
         [0030]     While considerable emphasis has been placed on the preferred embodiments, it will be appreciated that other embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention, and it is intended that the following claims be construed literally and/or according to the doctrine of equivalents as broadly as possible.