Abstract:
A system for mounting a catalytic converter of an exhaust system to an internal combustion engine includes a bracket adapted to fix the catalytic converter to the engine. A strap is adapted to circumferentially extend about a portion of the catalytic converter and clamp the catalytic converter to the bracket. The bracket includes a seat, a mounting pad and a compliant portion interconnecting the seat and the mounting pad. The seat supports a portion of the catalytic converter opposite the strap. The compliant portion includes a slot extending adjacent to the seat to reduce the stiffness of the bracket and allow the bracket to deflect during thermal expansion of the catalytic converter.

Description:
FIELD 
       [0001]    The present disclosure relates to a mounting arrangement for an automotive exhaust system. More particularly, the present disclosure relates to a leaf spring bracket for mounting a catalytic converter to an engine of a vehicle. 
       BACKGROUND 
       [0002]    This section provides background information related to the present disclosure which is not necessarily prior art. 
         [0003]    Typically, automotive vehicles including cars and trucks have an internal combustion engine (gasoline or diesel) which is coupled to a transmission and an axle assembly for providing power to the driven wheels of the vehicle. An engine exhaust system which typically includes one or more exhaust pipes, one or more catalytic converters, one or more mufflers and one or more tailpipes 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. 
         [0004]    Some vehicles are equipped with catalytic converters positioned adjacent to or very near the engine. Due to the weight of the catalytic converters and proximity to the engine, brackets mounted directly to the engine block or heads have been used to support the converters. At least one known converter mounting bracket cooperates with one or more metallic mesh biscuits positioned between the converter and the bracket. The metal mesh is intended to act as a strain relief joint to account for thermal expansion of the converter during operation. 
         [0005]    While the steel mesh biscuits may effectively reduce the stresses reached due to thermal expansion, these materials tend to crush and may permanently set during vehicle operation. A change in joint stiffness after minimal periods of use has also been noted. Unfortunately, changes in the characteristics of the steel biscuits also may cause changes in the noise, vibration and harshness characteristics of the exhaust system within the vehicle. Undesirable feedback to the vehicle operator may occur after a relatively short period of vehicle operation. 
         [0006]    Other catalytic converter mounting systems including elastomeric plastics or rubbers have not succeeded due to the relatively high temperature operating environment in which the catalytic converter mount must function. Accordingly, it may be desirable to provide a robust, high-temperature catalytic converter mount to account for thermal expansion of exhaust components. 
       SUMMARY 
       [0007]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0008]    A system for mounting a catalytic converter of an exhaust system to an internal combustion engine includes a bracket adapted to fix the catalytic converter to the engine. A strap is adapted to circumferentially extend about a portion of the catalytic converter and clamp the catalytic converter to the bracket. The bracket includes a seat, a mounting pad and a compliant portion interconnecting the seat and the mounting pad. The seat supports a portion of the catalytic converter opposite the strap. The compliant portion includes a slot extending adjacent to the seat to reduce the stiffness of the bracket and allow the bracket to deflect during thermal expansion of the catalytic converter. 
         [0009]    A system for mounting a catalytic converter of an exhaust system to an internal combustion engine includes a monolithic bracket having a substantially constant thickness being adapted to fix the catalytic converter to the engine. The bracket includes a seat adapted to support a portion of the catalytic converter. A mounting pad and a compliant portion interconnects the seat and the mounting pad. The compliant portion includes first, second and third hinges having reduced cross-sections to allow relative movement between the seat and the mounting pad during thermal expansion of the catalytic converter. 
         [0010]    Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
     
    
     
       DRAWINGS 
         [0011]    The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
           [0012]      FIG. 1  is a schematic depicting an exemplary vehicle having an internal combustion engine and an exhaust system; 
           [0013]      FIG. 2  is a fragmentary perspective view of a catalytic converter mounted to an engine with a leaf spring bracket according to the teachings of the present disclosure; 
           [0014]      FIG. 3  is an exploded perspective view of a catalytic converter and bracket; 
           [0015]      FIG. 4  is a front view of a portion of the bracket; 
           [0016]      FIG. 5  is a perspective view of a portion of the bracket; 
           [0017]      FIG. 6  is another perspective view of a portion of the bracket assembly; 
           [0018]      FIG. 7  is a front view of an alternate bracket; 
           [0019]      FIG. 8  is an exploded perspective view of another alternate bracket assembly; 
           [0020]      FIG. 9  is a perspective view of the alternate bracket assembly depicted in  FIG. 8 ; 
           [0021]      FIG. 10  is a perspective view of a catalytic converter coupled to the bracket depicted in  FIGS. 8 and 9 ; 
           [0022]      FIGS. 11 and 12  depict perspective views of another alternate bracket assembly; and 
           [0023]      FIGS. 13 and 14  depict perspective views of another alternate bracket assembly. 
       
    
    
       [0024]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0025]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0026]    Referring now to the drawings, in which like reference numerals designate like or corresponding parts throughout the several views, there is illustrated in  FIG. 1  an exhaust system in accordance with the present disclosure and which is designated by the reference numeral  10 . Exhaust system  10  is attached to an internal combustion engine  14 . Internal combustion engine  14  is designed to provide power to one or more drive wheels of the vehicle through a transmission (not shown) and one or more axle assemblies (not shown). 
         [0027]    Exhaust system  10  comprises a pair of forward catalytic converters  16 , a pair of forward exhaust pipes  17 , a mid-pipe  18 , a rear catalytic converter  20 , a rear exhaust pipe  22 , a muffler  24 , and a pair of tailpipes  26 . As illustrated in  FIG. 1 , exhaust system  10  routes the products of combustion for internal combustion engine  14  to the rear of the vehicle. While illustrated as routing products of combustion to the rear of the vehicle, exhaust system  10  can be configured to route the products of combustion to any peripheral location of the vehicle including but not limited to the side or sides of the vehicle. 
         [0028]    Forward catalytic converters  16  are attached to a pair of heads  28  that are fixed to an engine block  30  of internal combustion engine  14 . Exhaust flows in sequence through the forward catalytic converters  16 , forward exhaust pipes  17 , mid-pipe  18 , rear catalytic converter  20 , rear exhaust pipe  22 , muffler  24  and dual tail pipes  26 . It is within the scope of the present disclosure to have a single forward catalytic converter  16  attached to a single exhaust pipe to provide a single path exhaust system. It is also within the scope of the present disclosure to have the pair of forward catalytic converters  16  attached to a pair of mid-pipes  18  which can be attached to a pair of rear catalytic converters  20  which can be attached to a pair of rear exhaust pipes  22  which can be attached to a pair of mufflers  24  which can be attached to a pair of tailpipes  26  to provide a dual path exhaust system. Thus, exhaust system  10  can be configured to be a single path exhaust system, a dual path exhaust system or any other configuration of exhaust system known in the art. 
         [0029]    Each forward catalytic converter  16  is fixed to engine block  30  by a mounting bracket assembly  38 . Each forward catalytic converter  16  includes a first mounting flange  42  fixed to an inlet cone  44  as well as a second flange  46  fixed to an outlet cone  48 . An outer shell  49  is positioned between and fixed to inlet cone  44  and outlet cone  48 . First flange  42  includes a plurality of apertures  50  for receipt of fasteners (not shown) to fix forward catalytic converter  16  to one of heads  28 . Second flange  46  includes a pair of apertures  52  for receipt of fasteners interconnecting forward catalytic converter  16  with forward exhaust pipe  17 . Due to the substantial mass of each catalytic converter  16 , bracket assembly  38  is spaced apart from first flange  42  to further support converter  16  at head  28 . 
         [0030]    As shown in  FIGS. 2-7 , bracket assembly  38  also couples a heat shield  60  to outer shell  49  of forward catalytic converter  16 . Bracket assembly  38  includes a strap  66  fixed to a bracket  68  with fasteners  70 . Bracket  68  is preferably stamped from a sheet of metal having a substantially constant thickness. Bracket  68  includes a substantially planar plate  74  monolithically formed with and intersecting a mounting tab  76  at substantially 90 degrees. A first hinge  78  interconnects plate  74  and mounting tab  76 . A rolled flange  80  extends about the periphery of mounting tab  76  to increase its stiffness. A pair of apertures  82  extends through mounting tab  76 . A separately formed stanchion  84  is fixed to mounting tab  76  to orient bracket assembly  38  relative to internal combustion engine  14 . The axial length of stanchion  84  is set according to the desired orientation of bracket assembly  38  and forward catalytic converter  16 . A through bore  85  extends through stanchion  84  and is aligned with one of apertures  82  for receipt of fasteners (not shown) for fixing bracket assembly  38  to engine block  30 . 
         [0031]    Plate  74  includes a semi-cylindrically shaped seat  86 , a first land  88 , and a second land  90 . First land  88  includes an aperture  92  and second land  90  includes an aperture  93  for receipt of fasteners  70  for fixing strap  66  to bracket  68 . It should be appreciated that lands  88 ,  90  are integrally formed with and continuously extend from seat  86 . Seat  86  has a curvilinear shape sized to conform to an outer surface of outer shell  49 . Similarly, strap  66  has a curved shape sized to mate with a bottom groove surface  122  of heat shield  60 . As such, bracket assembly  38  couples forward catalytic converter  16  and heat shield  60  to internal combustion engine  14 . 
         [0032]    An arcuate slot  94  extends through plate  74 . A protrusion  96  is positioned adjacent to slot  94  to stiffen bracket  68 . Portions of protrusion  96  are shaped as first and second ribs  100 ,  102 . The position of ends  104 ,  106  of slot  94  and distal ends of ribs  100 ,  102  define portions having a reduced bending stiffness identified as second and third hinges  110 ,  112  respectively. 
         [0033]    In operation, flange  42  fixes one end of forward catalytic converter  16  to one of heads  28 . Bracket assembly  38  fixes another portion of forward catalytic converter  16  to engine block  30 . Bracket assembly  38  functions as a Y-shaped leaf spring having a predetermined compliance in one direction to account for the coefficient of linear thermal expansion of forward catalytic converter  16 . The greatest magnitude of dimensional change of catalytic converter  16  occurs along the axis of exhaust flow. As such, bracket assembly  38  is configured to deflect at first hinge  78 , second hinge  110  and third hinge  112  to maintain bracket internal stresses at acceptable levels as forward catalytic converter  16  lengthens during heating. Furthermore, bracket assembly  38  exhibits a substantially increased stiffness in the other two directions orthogonal to the direction of exhaust flow. Accordingly, a robust structural catalytic converter mount may be provided that is operable to account for the thermal expansion of the catalytic converter when its operating temperature changes from atmospheric ambient temperature to a maximum exhaust gas temperature. It is contemplated that forward catalytic converter  16  may be exposed to exhaust gas temperatures exceeding 700° C. 
         [0034]    Depending on the mass of forward catalytic converter  16 , the magnitude of thermal expansion and the orientation of forward catalytic converter  16  relative to the ground, it may be desirable to change the stiffness of bracket assembly  38 . In particular, the magnitude of an offset between a surface  126  of protrusion  96  and a surface  128  of plate  74  may be varied. In the bracket depicted in the Figures, the offset is approximately 2 mm. If greater stiffening is required, a larger offset may be formed. Similarly, the circumferential extent of slot  94  may be changed to change the stiffness of leaf spring bracket  68 . 
         [0035]    An alternate bracket assembly is depicted in  FIG. 7  and identified at reference numeral  200 . Bracket assembly  200  is substantially similar to bracket assembly  38 . Accordingly, only the differences between the two will be described. Bracket assembly  200  includes a plurality of webs  202  radially extending across slot  94  to change the stiffness of the bracket. Webs  202  are circumferentially spaced apart from one another to provide additional load paths during operation. 
         [0036]      FIGS. 8-10  depict another alternate bracket assembly identified at reference numeral  250 . Bracket assembly  250  is substantially similar to bracket assembly  38  except that a strap  252  is pivotally coupled to a bracket  254  by a pin  256 . A hinged end  258  of strap  252  includes folded over tabs  260 ,  262  forming eyelets  264 ,  266 . An aperture  268  extends through bracket  254 . Pin  256  may be press-fit within aperture  268  after extending through eyelets  264  and  266 . Once the assembly is complete, strap  252  is pivotally coupled to bracket  254 . One of fasteners  70  may couple the non-hinged end of strap  252  to bracket  254  as previously discussed in relation to bracket assembly  38 . 
         [0037]    Bracket  254  includes a simplified planar mounting tab  270 . A pair of apertures  272  extend through mounting flange  270  for receipt of fasteners  276  that may be useful for fixing bracket  254  to another bracket  278  that may be fixed to engine block  30  or one of heads  28 . The additional joint between bracket  254  and bracket  278  may be necessary due to the limited space available within an engine compartment of a vehicle. It is contemplated as part of the present disclosure to vary the stiffness of bracket  254  to account for the additional joint between bracket  254  and bracket  278 . Examples of contemplated changes in structure include a change in the size and shape of a rib  274  as well as a change in the size and shape of a slot  279  extending through bracket  254 . As previously described, changes in these geometrical features change the rate of the Y-shaped leaf spring portion formed between a land  280  and mounting tab  270  as well as the spring portion formed between a hinge end  282  and mounting tab  270 . 
         [0038]      FIGS. 11 and 12  depict another alternate bracket assembly identified at reference numeral  338 . Bracket assembly  338  is substantially similar to bracket assembly  38 . Accordingly, like elements will be identified with similar reference numerals increased by  300 . 
         [0039]    Bracket assembly  338  does not include a strap for fixing catalytic converter  16  to a bracket  368 . On the contrary, bracket  368  is fixed to catalytic converter  16  via a process such as welding. More particularly, a first seat  429  is integrally formed with and extends from first land  88 . First seat  429  includes a curved shape and is sized to conform to and contact outer shell  49  of forward catalytic converter  16 . Similarly, a second seat  431  is integrally formed with and extends from second land  390 . Second seat  431  is also shaped to contact outer shell  49  of forward catalytic converter  16 . 
         [0040]    Once bracket assembly  338  is properly positioned relative to forward catalytic converter  16 , first seat  429  and second seat  431  are fixed to outer shell  49  by a process such as welding. It should be appreciated that a singular semi-cylindrically shaped seat  86  is no longer provided in the embodiment depicted in  FIGS. 11 and 12 . First seat  429  and second seat  431  are circumferentially spaced apart from one another. A relief  433  extends between first seat  429  and second seat  431  to assure that a first hinge  435  and a second hinge  437  are provided to allow bracket  368  to deflect when forward catalytic converter  16  exhibits an increase in length due to its coefficient of thermal expansion. After bracket  368  is fixed to forward catalytic converter  16 , relief  433  remains spaced apart from outer surface  49 . Third hinge  412  remains as previously described in relation to third hinge  112 . 
         [0041]      FIGS. 13 and 14  depict another bracket assembly  538 . Bracket assembly  538  is substantially similar to bracket assembly  338  and like elements will be identified with reference numerals increased by  200 . In similar fashion to bracket assembly  338 , bracket assembly  538  does not incorporate the use of a strap surrounding forward catalytic converter  16 . 
         [0042]    An externally threaded stud  651  is fixed to an outer surface  549  of forward catalytic converter  16 . First and second seats  653 ,  655  are positioned at the distal ends of bifurcated bracket  568 . A first open ended slot  657  extends through first seat  653 . A second open ended slot  659  extends through second seat  655 . Another stud (not shown) is also fixed to forward catalytic converter  16  substantially diametrically opposed from stud  651 . The studs radially outwardly extend from catalytic converter  16  and may be translated into open ended slots  657 ,  659  during the exhaust system assembly process. A nut  661  is threadingly engaged with stud  651  to mount forward catalytic converter  16  to first seat  653 . Another nut  663  cooperates with the other stud to fix forward catalytic converter  16  to second seat  655 . The provision of recess  633  assures that load is transferred from forward catalytic converter  16  through first seat  653  and second seat  655  while the remaining portions of outer surface  549  are clear of bracket  568 . As such, a first hinge  665  and a second hinge  667  are provided to complement third hinge  612  as previously described. 
         [0043]    The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the disclosure, and all such modifications are intended to be included within the scope of the disclosure.