Abstract:
An exhaust system has a plurality of isolator assemblies which are used to mount the exhaust system to a vehicle. Each of the isolator assemblies has an exhaust rod which is attached to a component of the exhaust system and which includes a first end which engages an elastomeric isolator attached to the vehicle through a U-shaped member. Each of the first ends of the exhaust rods are aligned to be generally parallel with the longitudinal axis of the vehicle when the exhaust system is installed in the vehicle.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention relates to a mounting arrangement for an exhaust system of a vehicle. More particularly, the present invention relates to a unique exhaust isolator system that provides vibration isolation between the exhaust system and the vehicle while providing superior alignment capability during the assembly operation of the exhaust system.  
         BACKGROUND OF THE INVENTION  
         [0002]    Typically, automotive vehicles including cars and trucks have an internal combustion engine which is coupled to at least a transmission and a differential for providing power to the driven wheels of the vehicle. An engine exhaust system which typically includes an exhaust pipe, a catalytic converter and a muffler is attached to the engine to quiet the combustion process, to clean the exhaust gases and to route the products of combustion away from the engine. The internal combustion engine is supported in the vehicle on a set of engine mounts which are positioned between a frame or other supporting structure and the engine. The exhaust system is supported by exhaust mounts which are positioned between the exhaust system and the frame or other supporting structure of the body. In order to prevent engine vibrations from being transmitted to the car body, the exhaust mounts incorporate flexible mounting members or elastic suspension members. The exhaust mounts also include an upper hanger having one end secured to the vehicle body or the like and the other end connected to the flexible mounting member and a lower hanger having one end connected to the flexible member and the other end secured to the exhaust system.  
           [0003]    The elastic suspension member is typically designed to allow a large displacement in a first direction but it is restricted in its displacement in a second direction which is typically ninety degrees from the first direction. Thus, displacement or vibrations in the first direction are effectively absorbed while displacement or vibrations in the second direction are less effectively absorbed. In addition, the assembly of the vehicle and the exhaust system to the vehicle have to take into consideration the exhaust mounts and any preloading of the elastic members which can unnecessarily complicate the assembly process.  
           [0004]    While the prior exhaust mounts have proved effective in the isolation of engine vibrations, the continued development of these exhaust mounts has been directed toward mounting systems that are more effective in their isolation properties, that can function effectively in more than a single direction and which simplify the assembly of the vehicle and the assembly of the exhaust system to the vehicle.  
         SUMMARY OF THE INVENTION  
         [0005]    The present invention provides the art with a unique exhaust isolator system that provides vibration isolation between the exhaust system and the vehicle while providing superior alignment capability for the assembly of the exhaust system to the vehicle. The exhaust isolator system utilizes three isolators to support the muffler and the tailpipe assembly. One isolator is placed forward of the muffler, one isolator is placed rearward of the muffler and one isolator is placed on the tailpipe. Each isolator includes a metal bracket attached to the vehicle, an elastomer isolator supported by the metal bracket and a support rod which extends between the elastomer isolator and the exhaust system (muffler and tailpipe assembly). The support rods are all aligned parallel with the longitudinal axis of the vehicle. This allows the support rods to slide axially in the elastomer isolator thus preventing the isolator from over constraining the exhaust system as it heats up and expands to its operating state.  
           [0006]    Further areas of applicability of the present invention will become apparent from the detailed description provided hereinafter. It should be understood that the detailed description and specific examples, while indicating the preferred embodiment of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:  
         [0008]    [0008]FIG. 1 is a perspective view of an exhaust system which incorporates the unique exhaust isolator system in accordance with the present invention;  
         [0009]    [0009]FIG. 2 is a perspective view of one of the isolators illustrated in FIG. 1;  
         [0010]    [0010]FIG. 3 is a perspective of another one of the isolators shown in FIG. 1; and  
         [0011]    [0011]FIG. 4 is a perspective of another one of the isolators shown in FIG. 1. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0012]    The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.  
         [0013]    Referring now to the drawings in which like reference numerals designate like or corresponding parts throughout the several views, there is shown in FIG. 1, a unique exhaust isolator system in accordance with the present invention which is secured to a vehicle and which is designated generally by the reference numeral  10 . Vehicle  10  comprises an internal combustion engine (not shown), a body (not shown) and an exhaust system  16  which is attached to both the engine and the body. The internal combustion engine is designed to power one or more drive wheels of the vehicle.  
         [0014]    Exhaust system  16  comprises an intermediate pipe  22 , a muffler  24 , a tailpipe  26  and a plurality of isolator assemblies  30 ,  130  and  230 . Intermediate pipe  22  is typically connected to a catalytic converter (not shown) which is attached to an exhaust pipe which is in turn attached to an exhaust manifold (not shown) which is one of the components of the vehicle&#39;s internal combustion engine. The catalytic converter may be attached to a single exhaust pipe which leads to a single exhaust manifold or the catalytic converter can be attached to a branched exhaust pipe which leads to a plurality of exhaust manifolds. Also, intermediate pipe  22  can be attached to a plurality of catalytic converters which connect together prior to reaching muffler  24  using intermediate pipe  22  or the vehicle can have a plurality of exhaust pipes, a plurality of catalytic converters, a plurality of intermediate pipes  22  and a plurality of mufflers  24  which connect together using a single tailpipe  26 . In addition, the present application is applicable to exhaust systems which are termed “dual exhaust systems” in that they have two separate parallel exhaust systems extending from a single internal combustion engine.  
         [0015]    Exhaust system  16  is utilized to route the exhaust gasses from the engine to the rear area of the vehicle. While traveling from the engine to the rear of the vehicle, the catalytic converter cleans the exhaust gasses and muffler  24  quiets the noise created by the combustion process in the engine. Isolator assemblies  30 ,  130  and  230  support exhaust system  16  underneath the vehicle and they operate to prevent engine vibrations from being transmitted to the vehicle&#39;s body. In addition, isolator assemblies  30 ,  130  and  230  provide superior alignment capabilities during the assembly of exhaust system  16  into the vehicle.  
         [0016]    Referring now to FIG. 2, isolator assembly  30  comprises an exterior bracket  40 , an elastomeric isolator  42  and an exhaust rod  44 . Exterior bracket  40  comprises a generally U-shaped member  46  which is utilized to secure isolator assembly  30  to the vehicle. FIG. 2 illustrates isolator assembly  30  which is designed to be secured to the front side (in the vehicle&#39;s direction) of muffler  24 .  
         [0017]    U-shaped member  46  is illustrated having a first flange  50  and a second flange  52 . Each flange  50  and  52  is adapted to be secured to the vehicle. Flange  50  defines a tab  54  and flange  52  defines a through bolt hole  56 . Tab  54  is designed to engage a hole  58  formed in a portion of the vehicle&#39;s structure. A bolt  60  extends through bolt hole  56  for securing U-shaped member  46  of exterior bracket  40  and thus isolator assembly  30  to the vehicle by mating with a threaded member  62  attached to or formed as an integral member of a portion of the vehicle&#39;s structure.  
         [0018]    Elastomeric isolator  42  is disposed within the inner pocket formed by U-shaped member  46  and it is designed to mate with U-shaped member  46  by having a generally cylindrical end surface and to mate with a generally flat surface on the vehicle by having a generally planar end surface. Elastomeric isolator  42  can be formed from silicone (for high temperature applications), EPDM (ethylene-propylene-diene monomer) (for moderate temperature applications), natural rubber (for low temperature applications), or any other elastomer which meets the requirements of the application. Elastomeric isolator  42  can be bonded to U-shaped member  46 , if desired. Elastomeric isolator  42  defines a plurality of voids  64  which are engineered in size, shape and location to control the dynamic rate of isolator assembly  30 , the insertion force for isolator assembly  30 , the system durability requirements for isolator assembly  30  as well as other developmental and performance characteristics for isolator assembly  30 . Elastomeric isolator  42  also defines a through bore  66  through which exhaust rod  44  is inserted.  
         [0019]    Exhaust rod  44  is a formed rod which includes compound bends such that a first end  68  is positioned to axially engage bore  66  and a second end  70  is designed to mate with and be secured to a component of exhaust system  16 . In the illustrated embodiment, exhaust rod  44  is attached to the front of muffler  24  but it is within the scope of the present invention to attach exhaust rod  44  to any other component of exhaust system  16 , if desired.  
         [0020]    Referring now to FIG. 3, an isolator assembly  130  of a slightly different design is illustrated. Isolator assembly  130  comprises exterior bracket  40 , elastomeric isolator  42  and an exhaust rod  144 . Exterior bracket  40  comprises generally U-shaped member  46  which, as detailed above, is utilized to secure isolator assembly  130  to the vehicle. FIG. 3 illustrates isolator assembly  130  which is designed to be secured to the rear side (in the vehicle&#39;s direction) of muffler  24 .  
         [0021]    U-shaped member  46  is illustrated having first flange  50  and second flange  52 . Each flange  50  and  52  is adapted to be secured to the vehicle. Flange  50  defines tab  54  and flange  52  defines through bolt hole  56 . Tab  54  is designed to engage a hole  158  formed in a portion of the vehicle&#39;s structure. Bolt  60  extends through bolt hole  56  for securing U-shaped member  46  of bracket  40  and thus isolator assembly  30  to the vehicle by mating with a threaded member  162  attached to or formed as an internal member of a portion of the vehicle&#39;s structure.  
         [0022]    Elastomeric isolator  42  is disposed within the inner pocket formed by U-shaped member  46  and it is designed to mate with U-shaped member  46  by having a generally cylindrical end surface and to mate with a generally flat surface on the vehicle by having a generally planar end surface. Elastomeric isolator  42  can be formed from silicone, EPDM, natural rubber or other materials as detailed above. Elastomeric isolator  42  can be bonded to U-shaped member  46  if desired. Elastomeric isolator  42  defines a plurality of voids  164  which are engineered in size, shape and location to control the dynamic rate of isolator assembly  130 , the insertion force for isolator assembly  130 , the durability requirements for isolator assembly  130  as well as other developmental and performance characteristics for isolator assembly  130 . Voids  164  may or may not be the same as voids  64  of isolator assembly  30 . Elastomeric isolator  42  also defines a through bore  166  through which exhaust rod  144  is inserted.  
         [0023]    Exhaust rod  144  is a formed rod which includes compound bends such that a first end  168  is positioned to axially engage bore  166  and a second end  170  is designed to mate with and be secured to a component of exhaust system  16 . In the illustrated embodiment, exhaust rod  144  is attached to the rear of muffler  24  but it is within the scope of the present invention to attach exhaust rod  144  to any other component of exhaust system  16  if desired.  
         [0024]    Referring now to FIG. 4, an isolator assembly  230  of a slightly different design is illustrated. Isolator assembly  230  comprises an exterior bracket  240 , elastomeric isolator  42  and an exhaust rod assembly  244 . Exterior bracket  240  comprises a generally U-shaped member  246  which, similar to that described above for U-shaped member  46 , is utilized to secure isolator assembly  230  to the vehicle. FIG. 4 illustrates isolator assembly  230  which is designed to be secured to tailpipe  26 .  
         [0025]    U-shaped member  246  is illustrated having a first formed end  250  and second flange  52 . Formed end  250  and second flange  52  are adapted to be secured to the vehicle. Formed end  250  is contoured to mate with the supporting structure of the vehicle and it defines a through bolt hole  254 . A bolt extends through bolt hole  254  for securing U-shaped member  246  of bracket  240  and thus isolator assembly  230  to the vehicle by mating with a threaded member attached to or formed as an integral member of a portion of the vehicle&#39;s structure. Flange  52  defines bolt hole  56 . Bolt  60  extends through bolt hole  56  for securing U-shaped member  246  of bracket  240  and thus isolator assembly  
         [0026]    Elastomeric isolator  42  is disposed within the inner pocket formed by U-shaped member  246  and it is designed to mate with U-shaped member  246  by having a generally cylindrical end surface and to mate with a generally flat portion on the vehicle by having a generally planar end surface. Elastomeric isolator  42  can be formed from silicone, EPDM, natural rubber or other materials as detailed above. Elastomeric isolator  42  can be bonded to U-shaped member  246  if desired. Elastomeric isolator  42  defines a plurality of voids  264  which are engineered in size, shape and location to control the dynamic rate of isolator assembly  230 , the insertion force for isolator assembly  230 , the durability requirements for isolator assembly  230  as well as other developmental and performance characteristics for isolator assembly  230 . Void  264  may or may not be the same as voids  164  of isolator assembly  130  and may or may not be the same as voids  64  of isolator assembly  30 . Elastomeric isolator  42  also defines a through bore  266  through which exhaust rod assembly  244  is inserted.  
         [0027]    Exhaust rod assembly  244  comprises an exhaust rod  270  and a V-shaped bracket  272 . Exhaust rod  270  is a generally straight rod which is positioned to axially engage bore  266 . V-shaped bracket  272  is attached to exhaust rod  270  at one end and it is designed to mate with and be secured to a component of exhaust system  16  at its opposite end. In the illustrated embodiment, V-shaped bracket  272  is attached to tailpipe  26  but it is within the scope of the present invention to attach V-shaped bracket  272  to any other component of exhaust system  16  if desired. embodiment, V-shaped bracket  272  is attached to tailpipe  26  but it is within the scope of the present invention to attach V-shaped bracket  272  to any other component of exhaust system  16  if desired.  
         [0028]    Referring now to FIG. 1, exhaust system  16  includes isolator assembly  30  located forward of muffler  24 , isolator assembly  130  located behind muffler  24  and isolator assembly  230  located on tailpipe  26 . While exhaust system  16  is illustrated with three isolator assemblies  30 ,  130  and  230  being positioned at the specific locations detailed above, it is within the scope of the present invention to utilize a fewer number or a greater number of isolator assemblies located anywhere along exhaust system  16  as required by the specific application. Each isolator assembly  30 ,  130  or  230  provides a failsafe design by having U-shaped member  46  or  246  in connection with the mounting surface on the vehicle fully encircle exhaust rod  44 ,  144  or  244 . By fully encircling exhaust rod  44 ,  144  or  244 , exhaust system  16  is prevented from being unsupported at any isolator assembly should elastomeric isolator  42  deteriorate to the point of not being able to support exhaust system  16 .  
         [0029]    Each isolator assembly  30 , 130  and  230  is oriented with respect to the vehicle such that bores  66 , 166  and  266  of elastomeric isolator  42  and the mating end of exhaust rods  44 ,  144  and  244  extend generally parallel to the fore and aft direction of the vehicle or generally parallel to a longitudinal axis  88  defined by exhaust system  16  which is adapted to be parallel to the longitudinal axis of the vehicle which extends from the front center to the rear center of the vehicle. This unique orientation of isolator assemblies  30 ,  130  and  230  allows exhaust system  16  to be aligned using only one of isolator assemblies  30 ,  130  and  230  while the remaining isolator assemblies  30 , 130  or  230  can be delivered part-in-assembly with exhaust system  16  prior to being assembled to the vehicle. Furthermore, once all isolator assemblies  30 ,  130  and  230  are secured, exhaust system  16  is aligned in its natural or free state for noise, vibration and harshness (NVH) characteristics unlike the prior art exhaust isolator systems. An additional advantage to the longitudinal alignment of isolator assemblies  30 ,  130  and  230  is that they will allow for thermal growth of exhaust system  16 . This longitudinal alignment of exhaust rods  44 ,  144  and  244  allow the exhaust rods to individually and simultaneously slide longitudinally in elastomeric isolators  42  and thus prevent isolator assemblies  30 ,  130  and  230  from over-constraining exhaust system  16  as it heats up and lengthens to its operating state.  
         [0030]    Finally, the cylindrical shape of elastomeric isolator  42  allows it to be dynamically tuned in two directions using voids  64 ,  164  and  264 , as opposed to the conventional prior art two rod isolators which are unidirectional. This allows for increased isolation and precise tuning to minimize localized forces which are transmitted to the vehicle. In addition, the isolator in bracket design allows for extremely high resonant frequencies as opposed to the prior art designs which significantly lower vehicle side resonance. This allows added stiffness on the exhaust side rod to increase resonant frequencies of the entire isolator system.  
         [0031]    The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.