Abstract:
The present disclosure relates to an isolator assembly. The assembly has a housing with a bore. A resilient bushing is positioned within the bore of the housing. The bushing has a lower isolator spring element, a central region and an upper isolator spring element, wherein the central region has a smaller cross sectional area than each of the lower and upper isolator spring elements. The bushing has a bore extending at least partially axially therethrough. The lower and upper isolator spring elements are supported within axially spaced apart portions of the housing. A vertical hanger pin is secured within the bore of the bushing and projects outwardly therefrom to facilitate mounting the isolator assembly to an exhaust system component.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application No. 62/183,119, filed on Jun. 22, 2015. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure relates to a vertical hanger isolator. More particularly, the present disclosure relates to a vertical hanger isolator for an exhaust system. 
       BACKGROUND 
       [0003]    Hanger isolators are commonly used in automotive exhaust systems to reduce vibration transfer between components. For example, isolators are used to reduce vibrations induced from a running engine and/or road load conditions. However, commonly available isolators are designed to offer stiffness in a single direction like a two-hole pendulum. To provide support in more than one axial direction or to provide support of a roll (twisting) motion, isolators are used in pairs. These isolator pairs could be positioned on a non-aligned axis (e.g. 90 degree axis orientation) or positioned with a parallel axis where the isolator support housings fall within the same plane. For example, in order to attain roll (twist) stability the design standard is to put two or more isolators on misaligned axes in order to create a force couple supporting roll. Furthermore, commonly available isolators, as shown in  FIG. 8 , do not offer any conical ortorsional stiffness, requiring the use of at least two adjacent isolators. Adding an additional isolator to provide conical stiffness increases both the weight and the cost of the system. 
       SUMMARY 
       [0004]    In one aspect the present disclosure relates to an isolator assembly. The isolator assembly may include a housing having a bore, and a resilient bushing. The resilient bushing may have a lower isolator spring element, a central region and an upper isolator spring element, wherein the central region has a smaller cross sectional area than each of the lower and upper isolator spring elements. The resilient bushing has a bore extending at least partially axially therethrough. The lower and upper isolator spring elements may be supported within axially spaced apart portions of the housing. The isolator assembly may further include a vertical hanger pin secured within the bore of the resilient bushing and projecting outwardly therefrom to facilitate mounting the isolator assembly to an exhaust system component. 
         [0005]    In another aspect the present disclosure relates to an isolator assembly having a housing having a bore, and a resilient bushing. The resilient bushing may have a lower isolator spring element, a central region and an upper isolator spring element. The central region has a smaller cross sectional area than each of the lower and upper isolator spring elements, and the resilient bushing further has a bore extending at least partially axially therethrough. The upper isolator spring element may be located within the housing at a first end of the housing and concentric with the bore in the housing. The lower isolator spring element may be located at a second end of the housing and concentric with the bore in the housing. The bore of the resilient bushing is axially aligned with the bore of the housing. A pin is disposed in the bore of the resilient bushing and extends through the upper isolator spring element, through the central region and at least partially into the lower isolator spring element. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]      FIG. 1  is a perspective view of an exhaust system including a first embodiment of a hanger isolator assembly in accordance with the present invention; 
           [0007]      FIG. 2A  is an isometric cross-sectional side view of the hanger isolator assembly of  FIG. 1 ; 
           [0008]      FIG. 2B  is a cross-sectional side view of the hanger isolator assembly of  FIG. 1 ; 
           [0009]      FIG. 3  is a perspective view of an exhaust system including a second embodiment of a hanger isolator assembly in accordance with the present invention; 
           [0010]      FIG. 4A  is an isometric cross-sectional side view of the hanger isolator assembly of  FIG. 3 ; 
           [0011]      FIG. 4B  is a cross-sectional side view of the hanger isolator assembly of  FIG. 3 ; 
           [0012]      FIG. 5  is an isometric view of a third embodiment of a hanger isolator assembly in accordance with the present invention; 
           [0013]      FIG. 6  is a partial cross-sectional side view of the hanger isolator assembly of  FIG. 5 ; 
           [0014]      FIGS. 7A and 7B  are isometric and cross-sectional views, respectively, of a method of assembling a hanger isolator assembly in accordance with the present invention; 
           [0015]      FIG. 8  is a perspective view of a prior art hanger isolator that makes use of a pair of isolators positioned within a common place; 
           [0016]      FIG. 9  is a perspective view of an isolator assembly in accordance with another embodiment of the invention, wherein a resilient bushing of the assembly is provided to two distinct component parts; and 
           [0017]      FIG. 10  is a partial cross sectional view through the isolator assembly of  FIG. 10  in accordance with section line  10 - 10  in  FIG. 9 . 
       
    
    
     DETAILED DESCRIPTION 
       [0018]      FIG. 1  is a view of an engine exhaust system  10  including the isolator hanger assembly  100  in accordance with one or more preferred embodiments of the present invention. The engine exhaust system  10  includes an exhaust conduit  12  that interconnects different exhaust components  14  of the system  10 . Exhaust components  14  can be of the types including a muffler to reduce engine noise, a Selective Catalytic Reduction, SCR, to reduce engine NOx, or even a particulate filter to reduce engine particulate matter. A vertical hanger  16  is fixedly attached to the side of conduit  12  such as by welding and includes a vertical hanger pin  18  that is positioned in in a vertical (Z) direction. The vertical hanger pin  18  also includes an annular pin collar  20 , shown in  FIG. 2A , with an increased diameter in relation to the pin  18 . 
         [0019]      FIGS. 2A and 2B  illustrate the isolator hanger assembly  100  in greater detail. The isolator hanger assembly  100  includes a rigid housing  102  that may be coupled to a vehicle underbody through mounting portion  104 , which would receive a separate bolt. In at least one embodiment, the rigid housing  102  is constructed of die cast aluminum. The rigid housing  102  includes a central bore  106  configured to receive or accommodate one or more annular support journals  108  of a resilient isolator bushing  110 , which in one example may be a rubber bushing. For convenience, the resilient bushing will be hereafter referred to simply as “bushing  110 ”. 
         [0020]    The isolator hanger assembly  100  of  FIG. 2B  includes the two annular support journals  108  in a spaced apart configuration at opposing sides of the central bore  106 . The support journals  108  are located in circular portions  102   a  and  102   b  of the housing  102 . A rubber isolator bushing  110  is shown positioned within the central bore  106 . The bushing  110  comprises a lower isolator spring element  112 , a central region  114  and an upper isolator spring element  116 . The bushing  110  further includes an aperture  118  through an axial center thereof. The aperture  118  is axially aligned with the central bore  106  and is configured to receive the vertical hanger pin  18  therethrough. The larger diameter of the annular pin collar  20  prevents the over-insertion of the pin  18 . Optional through voids  130  in  FIG. 2A  may be also included for tuning stiffness in the fore-aft vehicle direction. 
         [0021]    The lower isolator spring element  112  and the upper isolator spring element  116  are aligned to produce a resisting force couple reaction that resists the conical input of a rolling exhaust bending moment, as indicated by arcuate line “A” in  FIG. 2B . The two spring elements  112 , 116  are designed to be soft in the X, Y and Z linear directions (i.e. side-side, up-down, front-back). For example, the X and Y support directions are coupled as the central region  114  translates toward the outer support journal  108 , while the Z support direction is coupled as the central region  114  telescopes along the axis of the vertical hanger pin  18  (i.e., along the Z axis in  FIG. 2B ). The reduced diameter of the central region  114  in comparison to the spring elements  112 ,  116  provides for several significant benefits. First, it reduces the overall stiffness of the bushing  110 . A bushing with high stiffness will have an increased spring rate which could prevent telescoping along the axis of the vertical hanger pin  18  (i.e., along the Z axis). Limiting the telescoping along the Z axis could lead to undesirable noise, vibration and harshness characteristics in the system. The reduced diameter of the central region  114  has the added benefit of significantly reducing the mass of the isolator hanger assembly  100 , and thus material costs as well. 
         [0022]    The vertical exhaust hanger  16  with pin  18  is fixed to the bushing  110  with a simple rubber interference fit within the inner diameter of the bushing  110 . Within the bushing  110 , an overmolded inner tube  120  is provided. Cutouts  122  or “windows” are provided through the rigid housing  102  exposing the internal area of the central bore  106  to allow access to the central region  114 . 
         [0023]      FIGS. 3, 4A and 4B  illustrate an engine exhaust system  10  including a hanger isolator assembly  200  in accordance with an alternative embodiment of the present invention. The hanger isolator assembly  200  comprises an isolator housing  202  having a mounting bolt/stud  224  and a resilient bushing  210 . In this embodiment, the mounting bolt/stud  224  is axially aligned with vertical hanger pin  18 . The axial alignment of the vertical hanger pin  18  and the mounting bolt/stud  224  allows the loading to be transferred from the exhaust system side of the hanger isolator assembly  200  to the body side of the hanger isolator assembly  200  without generating any additional roll or twist. Furthermore, the overmolded inner tube  220  includes a constriction  226  near the lower spring element  212  that prevents the vertical hanger pin  18  from pushing out of the lower spring element  212 . As such, an annular pin collar is not required. A lower pocket  228  is provided within isolator housing  202  that provides a space between the lower spring element  212  and the mounting bolt/stud  224 . The lower pocket  228  prevents the vertical hanger pin  18  from contacting the mounting bolt/stud  224  when the lower spring element  212  deforms in response to loading. Aperture  230  is provided to allow excess air to exit the lower pocket  228  to avoid any vacuum/pressure effect from application load stroking. Accordingly, only the elastomeric properties of the bushing  210  contribute to the vertical deflection of vertical hanger pin  18 . 
         [0024]      FIG. 5  illustrates a hanger isolator assembly  300  in accordance with another embodiment of the present invention. Hanger isolator assembly  300  includes a two-piece resilient bushing  310  that is split into a lower isolator spring element  312  and an upper isolator spring element  316 . Both of the spring elements are positioned within a bore  306  of a housing  302 . The use of two spring elements  312 / 316  allows the lower spring element  312  to be tuned differently than the spring element  316 , thus allowing for different isolation properties in different orientations. Isolator housing  302  includes reinforcement ribs  332  that further support the upper isolator spring element  316  to promote the transfer of loads around the cutouts  322 .  FIGS. 6 and 10  make component  110  with two PCs instead of one for simpler assembly. 
         [0025]      FIGS. 7A and 7B  illustrate a method of installing resilient bushing  310  to form a hanger isolator assembly  300 . The method may also be used with hanger isolator assemblies  100  and  200 . As illustrated, the lower isolator spring element  312  and upper isolator spring element  316  are installed into the central bore  306  of the housing  302  using an assembly tool  400 . To begin assembly, lower isolator spring element  312  is placed into the bore  306 . The outer diameter of the lower isolator spring element  312  is slightly smaller than the diameter of the upper isolator spring element  316  such that the lower isolator spring element  312  will easily penetrate the opening to the bore  306  but the upper isolator spring element  316  will not. Preferably, the outer diameter of the lower isolator spring element  312  is about 1 mm less than the outer diameter of the upper isolator spring element  316 . Assembly tool  400  comprises two pieces  400   a  and  400   b  that fit together around the housing  302  and the bushing  310 . Each piece  400   a  and  400   b  of the assembly tool  400  includes one or more protrusions  434  that align with the cutouts  322  in the housing  302  when the pieces  400   a  and  400   b  are clamped over the housing  302 . As force is applied to the assembly tool  400  in the downward direction, as shown in  FIG. 7B , the assembly tool  400  simultaneously forces both the upper isolator spring element  316  and the lower isolator spring element  312  downward and into a resistance fit against the housing  302 . More particularly, a top inner portion of the assembly tool  400  pushes against the upper isolator spring element  316  and the protrusions  434  simultaneously apply force to the lower isolator spring element  312 . 
         [0026]      FIGS. 6 and 10  illustrate an isolator assembly  500  in accordance with another embodiment of the invention. The isolator assembly  500  in this embodiment makes use of two independent resilient bushing components, an upper bushing component  510   a  and a lower bushing component  510   b.  The bushing components  510   a  and  510   b  are positioned face to face within a bore  506  of a housing  502  to form somewhat of a “sandwich” configuration. The housing also includes a bore  550  within which a mounting vertical hanger pin  524  is press fit. 
         [0027]    The bushing component  510   a  may include neck portions  552   a  and a bond portion  554   b,  and bushing component  510   b  may likewise include a neck portion  552   b  and a bond portion  554   b.  The two bushing components  510   a  and  510   b  are made from resilient material, for example rubber, and each could each be made from molded parts and may be press fit into the housing  502  from opposite directions. In this example each of the bond portions  554   a  and  554   b  include outer tube or sleeve portions  566   a  and  566 b, although it would be possible to mold bond portions  554   a  and  554   b  directly within the bore  506 . Alternatively, the bond portions  566   a  and  566   b  could be mechanically bonded to the wall of the bore  506 , without the presence of the sleeve portions  566   a  and  566   b,  by using a suitable adhesive, or rubber interference. 
         [0028]    Alternative embodiments of the invention could replace the two bushings with a pair of rubber sandwiches or a pair of molded parts. The two molded parts could be press fit into the housing from opposite directions. Alternatively, the rubber of the bushing could be mechanically bonded directly to the housing or molded directly to the housing itself. Additional information related to the present invention is included in the Appendix to the specification and incorporated in its entirety.