Abstract:
An exhaust treatment system includes an exhaust treatment device having a stepped outer diameter. First and second clamps each include a stepped inner diameter such that the clamps engage the exhaust treatment device and other portions of the exhaust treatment system when the exhaust treatment device is properly oriented. The exhaust treatment device interferes with one of the clamps to preclude coupling the exhaust treatment device to an adjacent portion of the exhaust treatment system when an attempt is made to install the exhaust treatment device in a reversed improper orientation. A consistent exhaust flow direction through an exhaust treatment device such as a diesel particulate filter may be maintained through use of the inventive system.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a divisional of U.S. patent application Ser. No. 13/039,559 filed on Mar. 3, 2011. The entire disclosure of the above application is incorporated herein by reference. 
     
    
     FIELD 
       [0002]    The present disclosure generally relates to a system for treating exhaust gases. More particularly, a system for interconnecting and supporting various exhaust treatment devices is described. 
         [0003]    BACKGROUND 
         [0004]    To reduce the quantity of NO x  and particulate matter emitted to the atmosphere during internal combustion engine operation, a number of exhaust aftertreatment devices have been developed. A need for exhaust aftertreatment systems particularly arises when diesel combustion processes are implemented. Typical aftertreatment systems for diesel engine exhaust may include one or more of a diesel particulate filter (DPF), a selective catalytic reduction (SCR) system, a hydrocarbon (HC) injector, and a diesel oxidation catalyst (DOC). 
         [0005]    During engine operation, the DPF traps soot emitted by the engine and reduces the emission of particulate matter (PM). Over time, the DPF becomes loaded and begins to clog. Periodically, regeneration or oxidation of the trapped soot in the DPF is required for proper operation. To regenerate the DPF, relatively high exhaust temperatures in combination with an ample amount of oxygen in the exhaust stream are needed to oxidize the soot trapped in the filter. 
         [0006]    The DOC is typically used to generate heat useful for regenerating the soot loaded DPF. When hydrocarbons (HC) are sprayed over the DOC at or above a specific light-off temperature, the HC will oxidize. This reaction is highly exothermic and the exhaust gases are heated during light-off. The heated exhaust gases are used to regenerate the DPF. 
         [0007]    Over time, however, the DPF may degrade and become less effective. Replacement of the DPF or another exhaust treatment device may be necessary. Alternatively, the exhaust treatment device may be serviced or otherwise rejuvenated when the exhaust treatment device is removed from the system. 
         [0008]    DPFs, DOCs and the like have been coupled to relatively small displacement internal combustion engines for automotive use. It may also be desirable to treat the exhaust emitted from engines in other applications including diesel locomotives, stationary power plants and marine vessels. These systems may be equipped with relatively large diesel compression engines. The exhaust mass flow rate from the larger engines may be more than ten times the maximum flow rate typically provided. The size and weight of the exhaust treatment devices required for large engines may make the components unwieldy and very costly. Therefore, a need may exist in the art for an arrangement to easily service and support the devices for treating the exhaust output from a large diesel engine. Some of the exhaust treatment devices such as DPFs are relatively fragile and susceptible to fracture. Care should be taken during DPF replacement and operation to avoid impact loading. Furthermore, it may be desirable to maintain a predetermined exhaust flow direction through the exhaust treatment device and also a predetermined rotational alignment between exhaust treatment devices. 
       SUMMARY 
       [0009]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0010]    An exhaust treatment system includes an emissions treatment device having an upstream end and a downstream end for treating exhaust emitted from an internal combustion engine. The exhaust treatment system includes a frame adapted to support first and second portions of the exhaust treatment system. The first and second portions of the system are spaced apart from one another. The emissions treatment device interconnects the first and second portions and is in receipt of exhaust from the first portion and provides treated exhaust to the second portion. A first bracket is fixed to the frame and includes one of a protrusion and a receptacle. A second bracket is adapted to be fixed to the emissions treatment device and includes the other of the protrusion and the receptacle. The protrusion is positioned within the receptacle when the emissions treatment device is properly positioned. The protrusion interferes with one of the second bracket and the emissions treatment device to preclude assembly when the emissions treatment device is improperly positioned. 
         [0011]    An exhaust treatment system includes first, second and third emissions treatment devices positioned in series fluid communication with one another. The second emissions treatment device is removable from between the first and third emissions treatment devices. A first bracket is coupled to one of the first and third emissions treatment devices and includes one of a protrusion and a receptacle. A second bracket is fixed to the second emissions treatment device and includes the other of the protrusion and the receptacle. The protrusion is positioned within the receptacle when the second emissions treatment device is properly positioned. The protrusion interferes with one of the first bracket and the second emissions treatment device to preclude assembly when the second emissions treatment device is improperly positioned. 
         [0012]    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 
         [0013]    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. 
           [0014]      FIG. 1  is a schematic depicting an exhaust aftertreatment system including a poka-yoke mounting arrangement; 
           [0015]      FIG. 2  is a perspective view of a portion of the exhaust aftertreatment system; 
           [0016]      FIG. 3  is another perspective view of the poka-yoke system; 
           [0017]      FIG. 4  is a side view of the poka-yoke mounting system; 
           [0018]      FIG. 5  is a schematic of an alternate poka-yoke system having exhaust treatment devices properly assembled; and 
           [0019]      FIG. 6  is a schematic depicting the alternate poka-yoke system restricting improper installation of an exhaust treatment device. 
       
    
    
       [0020]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0021]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0022]      FIG. 1  depicts an exemplary diesel exhaust gas aftertreatment system  10  for treating the exhaust from a diesel compression engine  16 . The exhaust may contain oxides of nitrogen (NO x ) such as nitric oxide (NO) and nitrogen dioxide (NO 2 ) among others, particular matter (PM), hydrocarbons, carbon monoxide (CO), and other combustion byproducts. 
         [0023]    Aftertreatment system  10  includes multiple exhaust treatment devices, such as a diesel oxidation catalyst  18 , connected downstream from engine  16  to receive the exhaust therefrom, a diesel particulate filter (DPF)  20  connected downstream from DOC  18 , and a NO x  reducing device  22 , such as a selective catalytic reduction catalyst (SCR) or a lean NO x  trap connected downstream from the DPF  20  to receive the exhaust therefrom. 
         [0024]    A regeneration unit  24  may be positioned upstream of DOC  18  to increase the temperature of the engine exhaust and enhance the conversion efficiency of the NO x  reducing device  22 . Regeneration unit  24  raises the temperature of the exhaust entering diesel oxidation catalyst  18  to approximately 285° C. or greater to allow active HC dosing for active regeneration of DPF  20 . 
         [0025]    Regeneration unit  24  includes an injector  26  for injecting a suitable reductant. Reductants may include urea, hydrogen or a hydrocarbon. A control system, shown schematically at  28  in  FIG. 1 , is provided to monitor and control injector  26 . Control system  28  may include suitable processor(s), sensors, flow control valves, electric coils, etc. to control injector  26 . 
         [0026]    As shown in  FIGS. 2-4 , DOC  18  and DPF  20  are interconnected by a first band clamp  40 . In similar fashion, DPF  20  and SCR  22  are coupled to one another with a second band clamp  42 . A first flange  46  is fixed to a first end  48  of DOC  18  by a suitable process such as welding. A second end  50  of DOC  18  is fixed to a first end  52  of DPF  20  by first band clamp  40 . A second end  54  of DPF  20  is fixed to a first end  56  of SCR  22  by second band clamp  42 . A second flange  58  is fixed to a second end  60  of SCR  22 . First flange  46  and second flange  58  are fixed to a frame of the vehicle to support and mount exhaust gas aftertreatment system  10  at a desired location. 
         [0027]    It should be appreciated that first flange  46  and second flange  58  are not directly fixed to DPF  20 . As such, vibrations and/or impact loading that may be applied to the vehicle frame will not be directly applied to DPF  20 . First band clamp  40  and second band clamp  42  each include an elastomeric material  62  acting as a damper between DOC  18  and DPF  20 , as well as between DPF  20  and SCR  22 . 
         [0028]    As previously discussed, it may be desirable to easily remove DPF  20  from aftertreatment system  10  and accurately reinstall the DPF after cleaning or replacement. A poka-yoke system  70  includes a first bracket assembly  72  coupled to a second bracket assembly  74  by a removable fastener  76 . A first end of bracket assembly  72  includes a flange  78  fixed to a first bar  80 . Flange  78  is fixed to first flange  46 . Second bracket assembly  74  includes a flange  82  fixed to a second bar  84 . Flange  82  is coupled to second flange  58  via threaded fasteners (not shown). As noted, the opposite ends of bracket assemblies  72 ,  74  are interconnected to one another with fastener  76 . 
         [0029]    Poka-yoke system  70  also includes a protrusion or first blade  86  fixed to first bar  80  that radially extends substantially parallel to and axially offset from flange  78 . A poka-yoke bracket  88  is fixed to an outer surface  89  of DPF  20  via a process such as spot welding. Poka-yoke bracket  88  is arcuately shaped and includes a receptacle or circumferentially extending slot  90  in receipt of first blade  86 . The overall length or circumferential extent of slot  90  corresponds to the tolerance afforded to rotational alignment between DPF  20 , DOC  18  and SCR  22 . Rotational alignment or “clocking” of the exhaust treatment devices may be important because one or more of the treatment devices may include sensors that must be aligned with one another within a certain tolerance to properly function. 
         [0030]    A second blade  96  is fixed to first bar  80 . Second blade  96  includes an inner curved surface  98  defining its radially inward extent. Second blade  96  extends radially inwardly a lesser distance than first blade  86 . A poka-yoke ring  100  is fixed to DPF  20  at a location axially spaced apart from poka-yoke bracket  88 . In the example shown, poka-yoke ring  100  may include a simple band clamp defined by a spring ring  102  having ends drawn together by a fastener  104 . 
         [0031]    Second blade  96  is axially offset from first end  52  of DPF  20  a distance substantially similar to the distance first blade  86  is axially offset from second end  54  of DPF  20 . By positioning the components in the manner described, a technician attempting to install DPF  20  in reverse will be precluded from doing so because first blade  86  will interfere with poka-yoke ring  100  due to the fact that no slot exists within poka-yoke ring  100 . Reversing the exhaust flow direction through the DPF may be detrimental to the operation of exhaust aftertreatment system  10 . 
         [0032]    Additionally, relative rotational misalignment will be prevented because first blade  86  would interfere with an outer surface  108  of poka-yoke bracket  88  if first blade  86  were not properly aligned with slot  90 .  FIG. 2  depicts a male radially extending element as first blade  86  with a female receiving element being slot  90 . It is contemplated that the relative positioning of the male and female members may be reversed without departing from the scope of the present disclosure. For example, a radially outwardly extending member may be fixed to DPF  20  and a receptacle, recess or slot may be formed in first bracket assembly  72 . 
         [0033]    When first band clamp  40  and second band clamp  42  are tightened, an outer surface  109  of poka-yoke ring  100  is spaced apart a minimal distance from surface  98  of second blade  96 . In similar fashion, an inner circumferential surface  110  of first blade  86  is spaced apart a relatively small distance from outer cylindrical surface  89  of DPF  20 . 
         [0034]    When used in conjunction with a large diesel engine such as that found on a locomotive or in a marine application, DPF  20  may weigh over 100 pounds. By defining the shape and location of first blade  86  and second blade  96 , poka-yoke system  70  provides a cradle for supporting DPF  20  during the processes of installing and removing DPF  20  from system  10 . In particular, outer surface  109  of poka-yoke ring  100  will engage surface  98  of second blade  96  and outer surface  89  of DPF  20  engages curved inner surface  110  of first blade  86  when first band clamp  40  and second band clamp  42  are released. To form a cradle and support DPF  20  as described, first bracket assembly  72  and second bracket assembly  74  are coupled to first flange  46  and second flange  58  at or near a point closest to the ground. Gravity will urge DPF  20  into contact with first blade  86  and second blade  96 . Once first band clamp  40  and second band clamp  42  have been removed or axially displaced to a location clear of DPF  20 , the DPF may be removed by radially translating the DPF in a direction opposite first blade  86  and second blade  96 . 
         [0035]    The reverse order of operations may be followed to install a cleaned DPF. For example, DPF  20  is oriented to position first end  52  at an upstream location. DPF  20  is lowered into contact with surface  110  of first blade  86  and surface  98  of second blade  96 . DPF  20  is rotated until first blade  86  is aligned with slot  90 . First band clamp  40  and second band clamp  42  are tightened. During the tightening process, outer surface  89  of DPF  20  disengages first blade  86  and second blade  96  to become coaxially aligned with DOC  18  and SCR  22 . 
         [0036]      FIGS. 5 and 6  depict an alternate poka-yoke system identified at reference numeral  200 . Poka-yoke system  200  includes a first band clamp  202  interconnecting a DOC  204  and a DPF  206 . A second band clamp  208  couples DPF  206  with an SCR  210 . DOC  204  includes a first upstream end  212  and a second downstream end  214 . DPF  206  includes a first upstream end  216  and a second downstream end  218 . SCR  210  includes a first upstream end  220  and a second downstream end  222 . 
         [0037]    Poka-yoke system  200  assures proper upstream and downstream end orientation of DPF  206  by configuring first band clamp  202  to include a stepped inner diameter. More particularly, an upstream end of first band clamp  202  includes a first inner cylindrical surface  226 . A downstream portion of first band clamp  202  includes an inner cylindrical surface  228  having a greater diameter than cylindrical surface  226 . Similarly, second band clamp  208  includes an inner cylindrical surface  232  positioned at an upstream end defining a diameter. A larger inner diameter is defined by an inner cylindrical surface  234 . Cylindrical surface  234  is positioned downstream from cylindrical surface  232 . 
         [0038]    DPF  206  includes a stepped outer diameter. A first upstream portion of DPF  206  includes an outer cylindrical surface  240 . A downstream reduced diameter portion is defined by outer cylindrical surface  242 .  FIG. 5  depicts a properly oriented DPF  206  coupled to DOC  204  by first band clamp  202 . DOC  204  includes an outer cylindrical surface  246  having a smaller outer diameter than outer surface  240  of DPF  206 . Outer surface  246  is sized to closely mate with inner surface  226  of first band clamp  202 . Outer surface  240  of DPF  206  is sized to cooperate with inner cylindrical surface  228  of first band clamp  202 . In similar fashion, SCR  210  includes an outer cylindrical surface  248  having an outer diameter larger than cylindrical surface  242  of DPF  206 . Outer cylindrical surface  248  is sized to cooperate with inner cylindrical surface  234  of second band clamp  208 . Reduced diameter outer cylindrical surface  242  cooperates with reduced diameter inner cylindrical surface  232  of second band clamp. 
         [0039]      FIG. 6  represents an interference condition that would exist if an operator attempted to install DPF  206  in reverse with downstream end  218  positioned upstream of upstream end  216 . An interference condition would exist between outer cylindrical surface  240  and inner cylindrical surface  232 . Furthermore, inner cylindrical surface  228  of first band clamp  202  would not engage reduced diameter outer cylindrical surface  242  of DPF  206 . As such, poka-yoke system  200  assures proper orientation of DPF  206 . 
         [0040]    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.