Abstract:
A method and apparatus for cleaning an exhaust treatment device including a fibrous insulation comprises providing a pulsed air flow to a first port of the exhaust treatment device. A vibration is input to the exhaust treatment device while the pulsed air flow is provided. Fibers are entrained in the air flow and purged from a second port of the exhaust treatment device.

Description:
FIELD 
       [0001]    The present disclosure generally relates to the assembly of exhaust treatment devices. More particularly, the present disclosure provides an apparatus and process for purging loose fibers of insulation from the exhaust treatment device. 
       BACKGROUND 
       [0002]    Exhaust gas treatment devices such as catalytic converters, diesel oxidation catalysts, diesel particulate filters, and the like are employed in various applications to physically and/or catalytically treat exhaust gases emitted from internal combustion engines. Many of the gas treatment devices include a substrate that may include a catalyst coating. In one configuration, the substrate may be surrounded by a mat of compressible fibrous material prior to being inserted into a housing compartment of the gas treatment device. 
         [0003]    Fibrous mat is typically provided in sheet form or in a roll that is cut to size to surround the appropriate substrate. Loose fibers may be formed during the mat cutting operation, the subsequent handling of the catalyst and mat, and during the time when the mat and substrate are being inserted into the housing. Depending on the location of the loose fibers, these fibers may become entrained in the exhaust gas stream and engage surfaces of the substrate or other downstream exhaust treatment devices. 
         [0004]    Other exhaust treatment devices include fibrous insulation positioned between inner and outer shells. Portions of the insulation are often exposed to the exhaust gas stream. Fibers of insulation may be loosened during the exhaust treatment device assembly process. Accordingly, there may be a need for an apparatus and process to remove loose fibers from recently assembly exhaust treatment devices. 
       SUMMARY 
       [0005]    This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
         [0006]    A method for cleaning an exhaust treatment device including a fibrous insulation comprises providing a pulsed air flow to a first port of the exhaust treatment device. A vibration is input to the exhaust treatment device while the pulsed air flow is provided. Fibers are entrained in the air flow and purged from a second port of the exhaust treatment device. 
         [0007]    An apparatus for cleaning an exhaust gas treatment device includes a source of air flow. An air flow chopper is in receipt of air from the source and is adapted to supply air pulses to the exhaust gas treatment device. A vibration device is adapted to provide a vibration to the gas treatment device while the air pulses flow through the gas treatment device to dislodge and purge loose fibers from the exhaust gas treatment device. 
         [0008]    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 
         [0009]    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. 
           [0010]      FIG. 1  is a cross-sectional view of an exemplary exhaust treatment device; and 
           [0011]      FIG. 2  is a schematic depicting an apparatus for purging loose fibers from an exhaust gas treatment device. 
       
    
    
       [0012]    Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
       DETAILED DESCRIPTION 
       [0013]    Example embodiments will now be described more fully with reference to the accompanying drawings. 
         [0014]      FIG. 1  depicts an exemplary exhaust treatment device identified at reference numeral  10 . Exhaust treatment device  10  includes a diesel oxidation catalyst assembly (DOC assembly)  12  coupled to a diesel particulate filter assembly (DPF assembly)  14  with a clamp  16 . DOC assembly  12  includes a ceramic substrate  18 , an inner shell  20 , an outer shell  22 , an inner end plate  24  and an outer end plate  26 . A fibrous mat  28  surrounds substrate  18  and is positioned between an outer surface of substrate  18  and an inner surface of outer shell  22 . Insulation  30  is positioned between inner shell  20  and outer shell  22  as well as between inner end plate  24  and outer end plate  26 . An inlet  32  extends through outer shell  22  and inner shell  20  to provide a passageway for exhaust to enter exhaust treatment device  10 . 
         [0015]    An insulator ring  36  defines a channel  38  in receipt of insulation  40 . A plurality of apertures  42  extend through insulator ring  36  to allow sensors (not shown) to extend into a cavity  46  positioned downstream of substrate  18 . 
         [0016]    DPF assembly  14  includes a mat  48 , a filter element  50 , an inner housing  52 , an outer housing  54 , an inner head plate  56  and an outer head plate  58 . A fibrous insulation  60  is positioned between inner housing  52  and outer housing  54  as well as between inner head plate  56  and outer head plate  58 . An outlet  61  extends through outer housing  54  and inner housing  52  at a position downstream from filter element  50 . Another sensor aperture  62  extends through outer housing  54  and inner housing  52  for receipt of a downstream sensor (not shown). When exhaust treatment device  10  is mounted to a vehicle, engine exhaust flows into inlet  32 , through substrate  18 , through cavity  46 , through filter element  50  and exits at outlet  61 . 
         [0017]    Mat  28 , mat  48 , insulation  30  and insulation  40  may be constructed from relatively brittle fibers that may break off from a sheet during initial cutting of the material, handling and/or installation into outer shell  22 . 
         [0018]      FIG. 2  depicts a cleaning apparatus  100  for removing loose insulation fibers and dust that may be contained within DOC assembly  12  after the DOC sub-assembly process has been completed. Prior to interconnecting DOC assembly  12  with DPF assembly  14 , a cleaning process is performed. Inlet  32  is coupled to a conduit  102 . Outer shell  22  is coupled to a baffle  104 . Baffle  104  is sized and shaped to direct the gas flow to and increase the flow velocity around apertures  42  and insulator ring  36 . Baffle  104  may restrict flow from a predetermined area in a cross section downstream of the device being cleaned so as to modify the air flow pattern within the device being cleaned. In the arrangement depicted in  FIG. 2 , baffle  104  forces the flow around apertures  42  at higher flow velocities as compared to when a baffle is not present. In many cases, such a baffle device can be used to alter the flow path and simulate downstream components at a reduced cost or create a smaller cleaner package space. 
         [0019]    Cleaning apparatus  100  includes a source of air flow  106 . It is contemplated that the airflow source provides clean air at ambient temperature. The entire cleaning apparatus  100  including air flow source  106  may be portable to allow positioning at different locations along the exhaust treatment device assembly line. A conduit  108  provides air flow to an inlet  110  of a flow chopper  112 . An outlet  114  of flow chopper  112  is in fluid communication with conduit  102 . Flow chopper  112  functions to vary the flow rate output at outlet  114 . Flow chopper  112  may be configured using a variety of structures including a rotating butterfly valve, a flapper valve and actuator combination, a ball valve and actuator combination, or any number of mechanical elements that may selectively restrict and unrestrict flow through flow chopper  112 . It is further contemplated that the flow rate exiting outlet  114  may range from a magnitude 30% greater than the maximum estimated flow rate through exhaust treatment device during vehicular operation to a minimum as low as zero. Other maximum and minimum values may also be set as long as a pulse of air is input to inlet  32 . Depending on the geometry of the flow chopper, the pulsed air input to DOC assembly  12  may be substantially shaped as a square wave or more closely represent a sinusoidal wave. 
         [0020]    Apparatus  100  also includes a vibration device  120  fixed to DOC assembly  12 . Vibration device  120  is operable to excite DOC assembly  12  to move loose insulation fibers and dust relative to outer shell  22 . Vibration device  120  may include impact hammers to impart a vibration to outer shell  22 . Alternatively or additionally, vibration device  120  may include a shaker assembly operable to displace outer shell  22  relative to the ground. The shaker assembly may be operable to translate and/or rotate outer shell  22  along multiple translation and rotational axes. 
         [0021]    In operation, cleaning apparatus  100  supplies pressurized air from flow source  106  through conduit  108  to flow chopper  112 . Flow chopper  112  provides a pulsed air output to DOC assembly  12 . As the pulsed air flows through DOC assembly  12 , vibration device  120  adds energy to outer shell  22  to displace loose fibers and entrain them within the air flowing through substrate  18 . During the cleaning process, the loose fibers exit DOC assembly  12  and enter baffle  104 . Baffle  104  includes an outlet  124  allowing the loosened fibers and dust to exit the cleaning apparatus. It is contemplated that the cleaning process may be completed in one minute or less. Once the loose fibers and dust have been purged from DOC assembly  12  it is decoupled from conduit  102  and baffle  104  for assembly to DPF assembly  14 . 
         [0022]    It should be appreciated that cleaning apparatus  100  may be useful for removing fibers and dust from other types of exhaust treatment devices including diesel particulate filters, selective catalytic reduction substrates, ammonia slip catalysts, or other exhaust treatment devices. Furthermore, while the exhaust treatment device shown in  FIG. 1  includes a DOC upstream of a DPF, other arrangements of exhaust treatment devices may also be treated with cleaning apparatus  100 . Multiple exhaust treatment devices may be positioned in series, parallel or series-parallel arrangements without departing from the scope of the present disclosure. 
         [0023]    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.