Patent Publication Number: US-7713493-B2

Title: Compact combination exhaust muffler and aftertreatment element and water trap assembly

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-part of U.S. patent application Ser. No. 11/243,694, filed Oct. 5, 2005, now U.S. Pat. No. 7,582,267 and a continuation-in-part of U.S. patent application Ser. No. 11/142,085, filed Jun. 1, 2005, now U.S. Pat. No. 7,347,044 which is a continuation-in-part of U.S. patent application Ser. No. 11/085,715, filed Mar. 21, 2005, now U.S. Pat. No. 7,114,330 which is a continuation of Ser. No. 10/376,424, filed Feb. 28, 2003 U.S. Pat. No. 6,868,670, all incorporated herein by reference. 
    
    
     BACKGROUND AND SUMMARY 
     The invention relates to vertical exhaust systems and exhaust water trap assemblies, including for heavy duty vehicles, such as trucks, tractors, off-road equipment, and the like which utilize a vertical exhaust system, for example in which the exhaust conduit extends vertically alongside the cab of the vehicle. 
     For reduced emissions, catalytic converters and soot filters have been incorporated in the exhaust system of buses, trucks, and so on. If the exhaust outlet is vertical, there is a possibility that water, such as rain, snow, or bus or truck wash, can enter the upper end of the exhaust system and flow downwardly into contact with the catalytic converter or soot filter unit. The water entering the system can be absorbed in the catalyst/filter mounting mat, e.g. vermiculite, that is typically located between the outer surface of the catalytic converter and the outer body of the exhaust conduit. Mounting mat that is exposed to water results in a much lower push-out force, a measure of the ability for the mat to retain the catalyst/filter in place. In another scenario, freezing of water in the catalytic converter can cause structural damage to the monolithic catalyst. As an additional problem, water flowing through the catalytic converter or soot filter may tend to wash particulate material downwardly where such material collects and clogs the lower surface of the catalytic converter/soot filter causing premature failure thereof. 
     The present invention arose during continuing development efforts directed toward an improved combination exhaust muffler and aftertreatment element and water trap assembly, including ultra-compact structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-6  are taken from above noted parent U.S. patent application Ser. No. 11/142,085. 
         FIG. 1  is a side sectional view of an exhaust water trap assembly. 
         FIG. 2  is a view of a portion of  FIG. 1  and showing an alternate embodiment. 
         FIG. 3  is a side sectional view of an exhaust water trap assembly. 
         FIG. 3A  is an enlarged view taken along line  3 A- 3 A of  FIG. 3 . 
         FIG. 3B  is an enlarged view taken along line  3 B- 3 B of  FIG. 3 . 
         FIG. 4  is a sectional view taken along line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a sectional view taken along line  5 - 5  of  FIG. 3 . 
         FIG. 6  is a sectional view taken along line  6 - 6  of  FIG. 3 . 
         FIGS. 7-10  are taken from above noted parent U.S. patent application Ser. No. 11/243,694. 
         FIG. 7  is a cutaway perspective view of an aftertreatment exhaust assembly. 
         FIG. 8  is an exploded perspective view of the assembly of  FIG. 7 . 
         FIG. 9  is like  FIG. 7  and shows another embodiment. 
         FIG. 10  is a cutaway exploded perspective view of the assembly of  FIG. 9 . 
         FIG. 11  is a side sectional view of a combination exhaust muffler and aftertreatment element and water trap assembly in accordance with the invention. 
         FIG. 12  is like  FIG. 11  and shows another embodiment. 
         FIG. 13  is a sectional view taken along line  13 - 13  of  FIG. 12 . 
         FIG. 14  is like  FIG. 11  and shows a further embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     The following description of  FIGS. 1-6  is taken from above noted parent U.S. patent application Ser. No. 11/142,085. 
       FIG. 1  shows an exhaust water trap assembly  40  including a housing  42  extending axially along a vertical axis  44  and having a housing sidewall  46 . The housing has a lower inlet  48  for receiving exhaust from an internal combustion engine through a catalytic converter or soot filter, and an upper outlet  50  for discharging the exhaust and which is spaced above lower inlet  48 . An internal exhaust tube  52  extends upwardly from lower inlet  48  and is spaced radially inwardly of housing sidewall  46  by a radial gap defining an annular space  54  therebetween. Exhaust tube  52  has a top end  56  vertically spaced below upper outlet  50  by an axial gap  58 . A dome cap or umbrella  60  on top end  56  spans internal exhaust tube  52  and blocks exhaust flow axially upwardly therepast, and blocks entry of water axially downwardly therepast into top end  56  of internal exhaust tube  52  from upper outlet  50  and instead diverts and sheds water radially outwardly into annular space  54 . Exhaust tube  52  is perforated as shown at perforations  62 , and hence exhaust flows axially upwardly as shown at arrow  64  from the internal combustion engine and the catalytic converter into assembly  40  through lower inlet  48  into interior  66  of internal exhaust tube  52 , and then flows radially outwardly through perforations  62  as shown at arrow  68  into annular space  54  and then flows axially upwardly as shown at arrow  70  through annular space  54  past dome cap  60  and then into an upper plenum  72  and then to outlet  50  as shown at arrow  74  for discharge vertically axially upwardly through external exhaust tube  76 . 
     A lower annular flange  78  has an inner circumference  80  at internal exhaust tube  52  and defining lower inlet  48 , and has an outer circumference  82  at housing sidewall  46  and spanning and closing annular space  54  at a lower end thereof to form a collection space and water trap  84 , comparable to water trap 27 in U.S. Pat. No. 5,321,215. An upper flange  86  has an inner circumference  88  spaced vertically above top end  56  of internal exhaust tube  52  and dome cap  60  by axial gap  58  and defining the noted upper outlet  50 , and has an outer circumference  90  at housing sidewall  46 . Dome cap  60  and upper flange  86  define upper outlet plenum  72  free of a perforated exhaust tube extending axially therethrough and into which exhaust would otherwise have to be re-introduced and which would otherwise increase restriction, for example, in the &#39;215 patent, eliminating re-introduction of exhaust into exhaust tube 15 through perforations 20. Upper outlet plenum  72  unobstructedly fully occupies the lateral cross-sectional area of housing  42 , without an exhaust tube, such as 15 of the &#39;215 patent, extending axially therethrough. 
     External exhaust tube  76  extends upwardly from upper outlet  50  at upper annular flange  86 . In one embodiment, a second upper annular flange  92  is spaced above upper annular flange  86  by an axial gap defining an upper annular space  94  axially between flanges  86  and  94  and radially between external exhaust tube  76  and housing sidewall  46 . Each of upper annular flanges  86  and  92  has an inner circumference  88  and  96 , respectively, mounted to external exhaust tube  76  at axially spaced locations therealong. This is desirable because it provides reinforcement against lever arm bending of exhaust tube  76  or extensions thereof, typically encountered in mounting of the exhaust system and in service during road and/or engine vibration. In a further embodiment, upper annular flange  86  may have one or more openings such as  98  therethrough communicating with upper annular space  94  to provide a resonant chamber in space  94 , for cancellation or damping of designated frequencies or harmonics. 
     In a desirable aspect, the construction of the system separates and spaces first and second tubes  52  and  76 , respectively. Second tube  76  is separate from and spaced vertically above first tube  52  by axial gap  58  therebetween defining upper outlet plenum  72  laterally spanning housing  42  above annular space  54  and above top end  56  of first tube  52 . Tube  76  extends axially upwardly from the housing for discharging exhaust. Dome cap  60  on top end  56  of tube  52  blocks exhaust flow axially upwardly therepast, such that exhaust flows through the perforated portion of tube  52  as shown at arrow  68  through perforations  62  into annular space  54  then into plenum  72  then to tube  76 . Dome cap  60  blocks entry of water axially downwardly therepast into top end  56  of tube  52  from tube  76  thereabove and instead diverts and sheds water radially outwardly into annular space  54 . Annular flange  78  extends laterally between first tube  52  and housing sidewall  46  below top end  56  of tube  52  and defines collection space  84  for water shed from dome cap  60  into annular space  54 . Flange  78  is preferably at the lower end of tube  52 . Housing sidewall  46  has one or more drain holes  100  therethrough above flange  78  for draining water from collection space  84 . If moisture collects in space  84  to the level of drain  100 , the excess moisture will drain outwardly of sidewall  46 . 
     A portion of the moisture flowing outwardly on dome cap or umbrella  60  may flow inwardly through perforations  62  and along the inner surface of tube  52 . This moisture flowing along the inner surface of tube  52  will be directed outwardly through the lowermost row of perforations  102  by a ring  104  secured to the inner surface of tube  52 , comparably to ring 22 in the &#39;215 patent. This moisture will then flow along the outer surface of tube  52  and be collected in collection space or trap  84 . Most moisture collected in space  84  will drain through hole  100 , however when the engine is started, any remaining moisture collected in collection space or trap  84  will be heated and evaporated and the vapor will pass out of the assembly through annular space  54  then upwardly as shown at arrows  70  and  74 . 
     In a desirable aspect, the separation of tubes  52  and  76  (instead of a single tube 15 as in the &#39;215 patent) enables the first tube  52  to have a different diameter than the second tube  76 . This is desirable in applications where the second tube  76  is limited or required to be of a certain diameter, e.g. 4″, to match system requirements, yet allowing the first tube  52  to be a larger diameter, e.g. 6″, to reduce restriction, backpressure, and to improve flow distribution across the catalyst or soot filter. If tubes  52  and  76  are a single unitary tube, then the diameter thereof must match system requirements, including outlet dimensional requirements, which in turn limits the diameter of the internal exhaust tube to a diameter which may unnecessarily introduce restriction or increase backpressure. Different diameter separated tubes  52   a  and  76   a  are illustrated in  FIG. 2 , which uses like reference numerals from above where appropriate to facilitate understanding. 
     First tube  52  extends along a first axial centerline, and second tube  76  extends along a second axial centerline. In one embodiment, the noted axial centerlines are axially aligned with each other as shown at  44 ,  FIG. 1 . In another embodiment,  FIG. 2 , the axial centerline  106  of first tube  52   a  is laterally offset from the axial centerline  108  of the second tube  76   a . This affords packaging flexibility, which has been particularly encountered in various bus applications where the customer has desired such offset for accommodating restricted compartments in the exhaust system. 
       FIGS. 3-6  show an exhaust water trap assembly  120  including a housing  122  extending axially along a vertical axis  124  and having a housing sidewall  126 . The housing has a lower inlet  128  for receiving exhaust as shown at arrows  130  from an internal combustion engine, and an upper outlet  132  for discharging the exhaust and spaced above lower inlet  128 . An internal exhaust tube or housing  134  extends upwardly from lower inlet  128  and is spaced radially inwardly of housing sidewall  126  by a radial gap  136  defining an annular space  138  therebetween. Internal exhaust tube or housing  134  houses an exhaust aftertreatment element  140 , e.g. a catalyst element and/or particulate soot filter, through which the exhaust flows upwardly. Internal exhaust tube  134  has a top end  142  vertically spaced below upper outlet  132  by an axial gap  144 . A dome cap  146  is at the top end  142  of and spans internal exhaust tube  134  and blocks entry of water axially downwardly therepast into top end  142  of internal exhaust tube  134  from upper outlet  132 , and instead diverts and sheds the water radially outwardly into annular space  138 . 
     Internal exhaust tube  134  has an upper reduced diameter section  148  which is perforated such that exhaust flows radially outwardly therethrough as shown at arrows  130   a . Dome cap  146  has a plurality of openings  150  therearound, for example as shown in  FIGS. 4 and 3A  at  150   a ,  150   b , etc., through which exhaust flows upwardly as shown at arrows  130   b , and through which water flows downwardly as shown at arrows  152 . The water flows downwardly as shown at arrows  152   a  into annular space  138 ,  FIGS. 3 ,  3 B. 
     A lower flange  154 ,  FIGS. 3 ,  3 B, has an inner circumference  156  at a lower section  158  of internal exhaust tube  134  and defines the noted lower inlet  128 . Flange  154  has an outer circumference  160  at outer housing sidewall  126  and spans and closes annular space  138  at a lower end  162  thereof to form a collection space  164  for the water. One or more drain holes  166  are provided through lower flange  154  for draining water from collection space  164 . Flanges  168  and  170  are spaced above flange  154  and extend between lower inlet section  158  of the internal exhaust tube and sidewall  172  of central section  174  of the internal exhaust tube. Flange  170  has one or more openings  176  therethrough communicating with the space  178  between flanges  168  and  170  to provide a resonant chamber in space  178 , for cancellation or damping of designated frequencies or harmonics. Water collection space  164  is sealed from resonant chamber  178  by flange  168  therebetween. 
     An upper annular flange  180 ,  FIG. 3 , has an inner circumference at upper outlet tube  182  spaced vertically above top end  142  of internal exhaust tube  134  and dome cap  146  by the noted axial gap  144  and defining the noted upper outlet  132 . Flange  180  has an outer circumference at outer housing sidewall  126 . Another flange  184  also extends between outlet tube  182  and housing sidewall  126  and is spaced below flange  180 . Flange  184  has one or more openings such as  186  therethrough communicating with annular space  188  between flanges  180  and  184  to provide a resonant chamber in space  188 , for cancellation or damping of designated frequencies or harmonics. Dome cap  146  and the upper flanges define an upper outlet plenum  144  free of a perforated exhaust tube extending axially therethrough and into which exhaust would otherwise would have to be re-introduced and which would otherwise increase restriction. Upper outlet plenum  144  fully occupies the entire lateral cross-sectional area of the housing without an exhaust tube extending axially therethrough. 
     Internal exhaust tube  134  has the noted lower section  158  of a first outer circumference and extending axially through lower flange  154  at the latter&#39;s inner circumference  156 . Internal exhaust tube  134  has the noted middle section  174  of a second outer circumference and extending axially upwardly from lower section  158  and defining at least in part the noted annular space  138  between outer housing sidewall  126  and the noted second outer circumference of middle section  174  at sidewall  172  of internal exhaust tube  134 . Internal exhaust tube  134  has the noted upper section  148  of a third outer circumference and extending axially upwardly from middle section  174  and is perforated as shown at  149  to pass exhaust radially outwardly therethrough as shown at arrows  130   a . The noted second outer circumference of middle section  174  is greater than each of the noted first and third outer circumferences of lower section  158  and upper section  148 , respectively. An intermediate annular flange  190 ,  FIG. 3 , is axially spaced between upper and lower flanges  180  and  154  and is axially spaced below dome cap  146 . Intermediate flange  190  is formed on internal exhaust tube  134  and transitions between the noted second and third outer circumferences and further diverts water into annular space  138 . The noted one or more drain holes  166  are through lower flange  154  at lower inlet  128  and drain water from annular space  138  and collection space  164 . Intermediate flange  190  has an inner circumference coextensive with the noted third outer circumference of upper section  148 . Intermediate flange  190  has an outer circumference coextensive with the noted second outer circumference of middle section  174 . Dome cap  146  has an outer circumference  192  greater than the noted third outer circumference at upper section  148  of internal exhaust tube  134 . Outer circumference  192  of dome cap  146  is greater than or equal to the noted second outer circumference of middle section  174 . Preferably, outer circumference  192  of dome cap  146  is at outer housing sidewall  126 , and dome cap  146  has the noted plurality of openings  150  extending axially therethrough and radially spaced between the noted third outer circumference at upper section  148  of internal exhaust tube  134  and outer circumference  192  of dome cap  146 . Openings  150  pass exhaust upwardly therethrough and pass water downwardly therethrough, as above noted for example at arrows  130   b  and  152 , respectively. 
     Housing  122  provides a first external housing extending axially along vertical axis  124  and having the noted first housing sidewall  126 . Internal exhaust tube  134  provides a second housing within the first housing  122  and concentrically surrounded thereby and extending axially along vertical axis  124 . Second internal housing  134  has a housing sidewall  172  spaced radially inwardly of first housing sidewall  126  by the noted radial gap  136  defining the noted annular space  138  therebetween. Second internal housing  134  has the noted lower inlet  128  for receiving exhaust from an internal combustion engine. First outer housing  122  has the noted upper outlet  132  for discharging the exhaust and is spaced above lower inlet  128 . The second inner housing includes the noted internal exhaust tube having the noted lower section  158  extending upwardly from lower inlet  128 , the noted middle section  174  extending upwardly from lower section  158  and defining at least in part the noted annular space  138 , and the noted upper section  148  extending upwardly from middle section  174  and having the noted top end  142  spaced below upper outlet  132  by the noted axial gap  144 . Dome cap  146  is provided at the noted top end  142  of and spans upper section  148  of the internal exhaust tube and blocks entry of water axially downwardly therepast into top end  142  of the internal exhaust tube from upper outlet  132  and instead diverts and sheds the water radially outwardly and then through holes  150  into annular space  138 . The internal exhaust tube or housing  134  is mounted within outer housing  122  by a plurality of radial spokes or legs  194 ,  FIG. 5 , which also maintain the radial gap spacing at  136  to provide annular space  138 . 
     As noted above, exhaust aftertreatment element  140  is housed in second housing  134 . The one or more drain holes  166  are at a vertical level below the vertical level of exhaust aftertreatment element  140 . As shown in  FIG. 3 , the one or more drain holes  166  are vertically spaced below exhaust aftertreatment element  140  by a vertical gap therebetween. The one or more drain holes  166  may be provided through lower flange  154 , as noted above. Alternatively or additionally, one or more drain holes may be provided through housing sidewall  126 , as shown in dashed line at  196 . Drain holes  166  may be vertically aligned with exhaust aftertreatment element  140  as shown, and/or may be radially offset therefrom, for example by being vertically aligned with annular space  138 . Drain holes  196  are vertically spaced below and radially offset from exhaust aftertreatment element  140 . 
     The above noted inner and outer circumferences of annular space  138  provided by the respective housing sidewalls, and the noted inner and outer circumferences of the respective flanges, may have various shapes including cylindrical shapes, oval shapes, racetrack shapes, and other closed loop configurations. The term annular herein includes such shapes, and the terms inner and outer circumferences include the concording perimeter shapes thereof. Furthermore, respective inner and outer circumferences may or may not have identical shapes, for example an inner circumference may be round while the outer circumference is oval, and vice versa, etc. The inner and outer circumferences may share the same coincident vertical axis, or may have radially or laterally offset axes. The inlet and outlet may share the same coincident vertical axis, or may have different axes, as well as inner and outer circumferences of differing shape and/or alignment. The inlet and outlet may extend vertically parallel to vertical axis  124  as shown, or alternatively may extend radially or laterally through a respective housing sidewall, or may extend at some other angle relative to vertical. 
     The following description of  FIGS. 7-10  is taken from above noted parent U.S. patent application Ser. No. 11/243,694,  FIGS. 1-4 , respectively. 
       FIGS. 7 ,  8  show an aftertreatment exhaust assembly  210  having a housing  212  extending axially along axis  213  and containing an aftertreatment element, for example one or both of a particulate soot filter  214  and a catalyst element  216 . The housing has an inlet  218  and an outlet  220  communicating respectively with distally opposite axial ends  214   a  and  214   b  of aftertreatment element  214 , and  216   a  and  216   b  of aftertreatment element  216 . Exhaust flows from inlet  218  then axially through aftertreatments element  216 ,  214  then to outlet  220 . The housing has housing sections  222  and  224  meeting at a junction at joint  226  axially between axial ends  214   a  and  214   b  of aftertreatment element  214 . The housing has housing sections  224  and  228  meeting at junction  230  axially between aftertreatment elements  214  and  216 . Alternatively, joint  230  may be axially between axial ends  216   a  and  216   b  of aftertreatment element  216 . 
     Joint  226  is a service joint. Housing sections  222  and  224  are separable from each other at service joint  226  such that upon separation of housing sections  222  and  224 , axial end  214   a  of aftertreatment element  214  is axially spaced beyond housing section  224 , and the aftertreatment element is readily accessible, for ease of servicing, e.g. cleaning. During such servicing, aftertreatment element  214  will typically, though not necessarily, remain attached to housing section  224 , e.g. by welding. Connection  232  connects housing sections  222  and  224  to each other at service joint  226 . In one form, the connection  232  is a band clamp known in the prior art, e.g. an inverted truncated V-shape band clamp, though other types of connections may be used, for example a bolted flange connection, or other typical arrangements for connecting housing or body sections. In some embodiments, a gasket  234  is provided between housing sections  222  and  224  at joint  226 . A connection  236  connects housing sections  224  and  228  to each other at joint  230 , which connection may be a band clamp, e.g. the noted standard inverted truncated V-shape type clamp, or other connections, as noted. In some embodiments a gasket  238  is provided between housing sections  224  and  228  at joint  230 . Inlet  218  may extend radially from the housing as shown, or alternatively the inlet may extend axially from the housing as shown in dashed line at  218   a . Outlet  220  may extend radially from the housing as shown, or alternatively may extend axially from the housing as shown in dashed line at  220   a.    
     In  FIGS. 7 ,  8 , housing section  222  is an outlet housing section. Aftertreatment element  214  extends axially into outlet housing section  222  along a first axial direction  240 , and has an outlet axial end  214   a  within outlet housing section  222 . Outlet housing section  222  has a sidewall  242  extending axially between first and second end walls  244  and  246  and of larger diameter than aftertreatment element  214  and providing an outlet plenum  250  of reduced restriction. End wall  244  of outlet housing section  222  is axially spaced from outlet axial end  214   a  of aftertreatment element  214  along the noted first axial direction  240 . End wall  246  of outlet housing section  222  is axially spaced from outlet axial end  214   a  of aftertreatment element  214  along a second axial direction  252 , which second axial direction  252  is opposite to the noted first axial direction  240 . An inner end wall  254  may be provided in outlet housing section  222 , which end wall  254  may be perforated or otherwise have apertures such as  256  therethrough for forming a resonant chamber between end walls  254  and  246  for resonant tuning purposes. In further embodiments, an enlarged reduced restriction inlet plenum is provided in addition to or instead of outlet plenum  250 . 
     Sidewall  242  of outlet housing section  222  has a first span  258  extending from end wall  244  axially along the noted second axial direction  252  to a midpoint  260  radially aligned with outlet axial end  214   a  of aftertreatment element  214 . Sidewall  242  has a second span  262  extending from midpoint  260  axially along the noted second axial direction  252  to end wall  246 . Span  258  and end wall  244  define an open volume first plenum section  264  at outlet axial end  214   a  of aftertreatment element  214  and extending axially along the noted first axial direction  240  therefrom. Span  262  and end wall  246  define an annular volume second plenum section  266  at outlet axial end  214   a  of aftertreatment element  214  and extending axially along the noted second axial direction  252  therefrom and in circumscribing relation to aftertreatment element  214 . In one embodiment, the axial length of second span  262  is greater than the axial length of first span  260  to reduce and save space at outlet axial end  214   a  of aftertreatment element  214  along the noted first axial direction  240  therefrom and reduce the amount of axial extension of housing  212  in the noted first axial direction  240  beyond outlet axial end  214   a  of aftertreatment element  214 . Further in the preferred embodiment, sidewall  242  of outlet housing section  222  is of larger diameter than housing section  224 . 
     Outlet  220  is provided by an outlet tube extending radially from outlet housing section  222  at any desired circumferential position therearound, which is an advantage for accommodating different engine compartment requirements. In one embodiment, outlet tube  220  is radially aligned with outlet axial end  214   a  of aftertreatment element  214 . Joint  230  is axially spaced from joint  226  by housing section  224  therebetween. Inlet  218  communicates with housing section  228 , and outlet  220  communicates with housing section  222 . Joint  230  is axially between joint  226  and inlet  218 . Joint  230  is axially spaced from joint  226  on the opposite axial side thereof from end  214   a  of aftertreatment element  214 . Joint  230  is slightly axially spaced from aftertreatment element  214 . Housing section  224  axially spans axial end  214   b  of aftertreatment element  214 . Axial end  214   b  of aftertreatment element  214  is axially between joints  226  and  230 . 
       FIGS. 9 ,  10  show another embodiment and use like reference numerals from above where appropriate to facilitate understanding. Aftertreatment exhaust assembly  270  includes a housing  272  extending axially along axis  213  and containing at least one aftertreatment element, and in some embodiments two aftertreatment elements, namely a particulate soot filter  214  and a catalyst element  216 . The housing has an inlet  218  and an outlet  220  communicating respectively with axially distally opposite axial ends of the aftertreatment elements. Exhaust flows from inlet  218  then axially through the aftertreatment elements then to outlet  220 . The housing has first, second, third and fourth sections  274 ,  276 ,  278 ,  280 . First and second housing sections  274  and  276  meet at a first joint  282 . Second and third housing sections  276  and  278  meet at second joint  284 . Third and fourth housing sections  278  and  280  meet at a third joint  286 . Joint  282  is axially between axial ends  214   a  and  214   b  of aftertreatment element  214 . Respective housing sections  274  and  276  on opposite axial sides of joint  282  are separable from each other at joint  282  such that upon separation of respective housing sections  274  and  276  the noted axial end  214   a  of aftertreatment element  214  extends axially beyond housing section  276 , and the aftertreatment element is readily accessible for ease of servicing. 
     In  FIGS. 9 ,  10 , joint  284  is axially spaced from joint  282  on the opposite axial side thereof from axial end  214   a  of aftertreatment element  214 . Joint  284  is slightly axially spaced from aftertreatment element  214 . Alternatively, joint  284  may be axially between axial ends  216   a  and  216   b  of aftertreatment element  216 . Housing section  276  axially spans axial end  214   b  of aftertreatment element  214 . Inlet  218  is at housing section  280 , and outlet  220  is at housing section  274 , though this arrangement may be reversed. The joints may be clamped by respective connections, e.g. band clamps  288 ,  290 ,  292 , as above, and may have respective gaskets  294 ,  296 ,  298  between respective housing sections, as above. 
     The systems provide a method for servicing an aftertreatment exhaust assembly comprising providing a joint as a service joint, as noted, at a location axially between the axial ends  214   a  and  214   b  of the aftertreatment element  214 , and separating the housing sections  222  and  224 ,  274  and  276 , from each other at the service joint  226 ,  282 , such that upon separation of the noted housing sections, axial end  214   a  of the aftertreatment element  214  is axially spaced beyond the housing section  224 ,  276 , and servicing the aftertreatment element  214 . The system also provides a method for saving space in an aftertreatment exhaust assembly comprising providing an outlet housing section  222  wherein the aftertreatment element  214  extends axially into such outlet housing section  222 , with the outlet axial end  214   a  of the aftertreatment element  214  being within outlet housing section  222 , and providing the outlet housing section  222  with a sidewall  242  extending axially between first and second end walls  244  and  246  and of larger diameter than the aftertreatment element  214  and providing an outlet plenum  250  of reduced restriction and reduced axial extension along the noted first axial direction from the outlet axial end  214   a  of the aftertreatment element  214 . The method further involves providing the joint  226  at a location axially between the axial ends  214   a  and  214   b  of the aftertreatment element  214 . The method further involves spacing the first end wall  244  of the outlet housing section  222  axially from the outlet axial end  214   a  of the aftertreatment element  214  along the noted first axial direction  240 , spacing the second end wall  246  and/or  254  of the outlet housing section  222  axially from the outlet axial end  214   a  of the aftertreatment element  214  along the noted second axial direction  252 , providing the sidewall  242  of the outlet housing section  222  with a first span  258  extending from first end wall  244  axially along the noted second axial direction  252  to a midpoint  260  radially aligned with the outlet axial end  214   a  of the aftertreatment element  214 , providing the sidewall  242  of the outlet housing section  222  with a second span  262  extending from the midpoint  260  axially along the noted second axial direction  252  to the noted second end wall  246 , providing the first span  258  and the first end wall  244  defining an open volume first plenum section  264  at the outlet axial end  214   a  of the aftertreatment element  214  and extending axially along the noted first axial direction  240  therefrom, providing the second span  262  and the second end wall  246  defining an annular volume second plenum section  266  at the outlet axial end  214   a  of the aftertreatment element  214  and extending axially along the noted second axial direction  252  therefrom and in circumscribing relation to the aftertreatment element  214 . The method further involves providing the second span  262  of greater axial length than the first span  258  to reduce and save space at the outlet axial end  214   a  of the aftertreatment element  214  along the noted first axial direction  240  therefrom and reduce the amount of axial extension of the housing  212  in the noted first axial direction  240  beyond the outlet axial end  214   a  of the aftertreatment element  214 . 
       FIG. 11  shows a combination exhaust muffler and aftertreatment element and water trap assembly  310 . The aftertreatment element  312  is selected from the group consisting of at least one of a catalyst element and a particulate soot filter. Assembly  310  includes a housing  314  extending axially along a vertical axis  316  and having a housing sidewall  318 . The housing has a lower inlet  320  for receiving exhaust as shown at arrow  322  from an internal combustion engine, and has an upper outlet  324  for discharging the exhaust as shown at arrow  326  and spaced above lower inlet  320 . Aftertreatment element  312  is housed in the housing and spaced radially inwardly of housing sidewall  318  by a radial gap  328  defining an annular space therebetween, which annular shape may be circular, oval, racetrack shaped, obround, or other closed-loop shapes. A dome cap  330  is provided in the housing above aftertreatment element  312  and below upper outlet  324  and blocks entry of water as shown at arrow  332  downwardly therepast into aftertreatment element  312  from upper outlet  324  and instead diverts and sheds the water radially outwardly as shown at arrows such as  334  into annular space  328 . The water flows axially downwardly as shown at arrows such as  336  in annular space  328 , and is drained from annular space  328  by one or more drain holes  338  as shown at arrow  340 . The housing has a lower flange  342  spanning and closing annular space  328  to form a collection space  344  for the water. The one or more drain holes such as  338  are formed through lower flange  342 . Alternatively or additionally, one or more drain holes such as  339  may be formed through housing sidewall  318 . 
     In  FIG. 11 , a perforated tube  346 , having perforations as shown at  348 , extends axially in the housing between lower flange  342  and dome cap  330  and through which exhaust flows radially outwardly through perforations  348 . Perforated tube  346  is in annular space  328  and is radially between aftertreatment element  312  and housing sidewall  318 . Dome cap  330  is axially spaced above aftertreatment element  312  by a first axial gap  350 , and is axially spaced below upper outlet  324  by a second axial gap  352 . Aftertreatment element  312  has an inlet face  354  facing axially downwardly toward lower inlet  320 , and has an outlet face  356  facing axially upwardly toward dome cap  330  and axially spaced therebelow by axial gap  350 . Perforated tube  346  divides annular space  328  into a first annular subspace  356  and a second annular subspace  358 . Perforated tube  346  is radially spaced outwardly of aftertreatment element  312  by first annular subspace  356  therebetween. Housing sidewall  318  is radially spaced outwardly of perforated tube  346  by second annular subspace  358  therebetween. 
     Perforated tube  346  has a first axial extension portion  360  horizontally aligned with axial gap  350  above outlet face  356  of aftertreatment element  312 . Perforated tube  346  has a second axial extension portion  362  below first axial extension portion  360  and horizontally aligned with aftertreatment element  312  below outlet face  356  thereof. Exhaust flows upwardly as shown at  322  through aftertreatment element  312  as shown at arrows such as  364  from inlet face  354  then upwardly as shown at arrows  366  to outlet face  356  then axially upwardly as shown at arrows  368  into axial gap  350  then radially outwardly as shown at arrows  370  in first axial gap  350  then along first and second branches as shown at arrows  372  and  374 . First branch  372  extends radially outwardly as shown at arrow  376  through first axial extension portion  360  of perforated tube  346  then axially upwardly as shown at arrows  378  in second annular subspace  358 . Second branch  374  extends axially downwardly as shown at arrows  380  in first annular subspace  356  then radially outwardly as shown at arrows  382  through second axial extension portion  362  of perforated tube  346  then axially upwardly as shown at arrows  384  in second annular subspace  358  and rejoining the noted first branch. The exhaust then flows as shown at arrows  386  radially inwardly in axial gap  352  and exits at upper outlet  324  as shown at arrow  326 . The noted second branch  374  provides double flow reversal from outlet face  356  of aftertreatment element  312  to first annular subspace  356  to second annular subspace  358 , i.e. a first flow reversal from upward axial flow  368  to downward axial flow  380 , and a second flow reversal from downward axial flow  380  to upward axial flow  384 . 
     A dam  388 ,  FIG. 11 , is provided in first annular subspace  356  between aftertreatment element  312  and perforated tube  346 . Dam  388  circumscribes aftertreatment element  312  and extends axially upwardly from lower flange  342  to an upper axial end  390  below outlet face  356  of aftertreatment element  312 . Dam  388  blocks water flow to aftertreatment element  312 . The one or more drain holes  338  are radially outward of dam  388 . An extension wall  392  circumscribes and extends axially along aftertreatment element  312  and may include the above noted mounting mat  394 , such as vermiculite, therebetween. Extension wall  392  is radially between aftertreatment element  312  and dam  388 . Extension wall  392  extends axially upwardly beyond dam  388  toward outlet face  56  and in one embodiment along the entire length of aftertreatment element  312 . In an alternate embodiment, dam  388  is eliminated, and wall  392  acts as the water dam. In  FIG. 11 , dome cap  330  has an outer circumference  396  spaced radially inwardly of housing sidewall  318  by a radial gap  398  axially above and axially aligned with annular space  328 . Outer circumference  396  is at perforated tube  346 . 
       FIGS. 12 ,  13  show another embodiment and use like reference numerals from above where appropriate to facilitate understanding. In  FIGS. 12 ,  13 , dome cap  330   a  has an outer circumference  396   a  at housing sidewall  318 , and has a plurality of perimeteral apertures such as  400  axially above and axially aligned with annular space  328 . As in  FIG. 11 , exhaust in  FIG. 12  flows axially upwardly through aftertreatment element  312  from inlet face  354  to outlet face  356  then axially upwardly at  368  into axial gap  350  then radially outwardly at  370  then in a loop extending axially downwardly at  380  in the noted annular space then radially outwardly at  382  in the annular space then axially upwardly at  384  in the annular space, providing double flow reversal from outlet face  356  of aftertreatment element  312  from upward axial flow  368  to downward axial flow  380  to upward axial flow  384 . The exhaust also flows radially outwardly as shown at  376 . 
       FIG. 14  shows a further embodiment, and uses like reference numerals from above, with the postscript “b”, to facilitate understanding. Combination exhaust muffler and aftertreatment element and water trap assembly  310   b  includes aftertreatment element  312   b  selected from the group consisting of at least one of a catalyst element and a particulate soot filter. Assembly  310   b  includes housing  314   b  extending vertically along vertical axis  316   b  and having a housing sidewall  318   b . The housing has a lower inlet  320   b  for receiving exhaust as shown at arrow  322   b  from an internal combustion engine, and has an upper outlet  324   b  for discharging the exhaust as shown at arrow  326   b  and spaced above lower inlet  320   b . Aftertreatment element  312   b  is housed in the housing and spaced radially inwardly of housing sidewall  318   b  by radial gap  328   b  defining an annular space therebetween, which annular shape may be circular, oval, racetrack shaped, obround, or other closed-loop shapes. A dome cap  330   b  is provided in the housing above aftertreatment element  312   b  and below upper outlet  324   b  and blocks entry of water as shown at arrow  332   b  downwardly therepast into aftertreatment element  312   b  from upper outlet  324   b  and instead diverts and sheds the water radially outwardly as shown at arrows  334   b  into annular space  328   b . The water flows axially downwardly as shown at arrow  336   b  in annular space  328   b , and is drained from annular space  328   b  by one or more drain holes  338   b  as shown at arrow  340   b . The housing has a lower flange  342   b  spanning and closing annular space  328   b  to form a collection space  344   b  for the water. The one or more drain holes such as  338   b  are formed through lower flange  342   b . Alternatively or additionally, one or more drain holes such as  339   b  may be formed through housing sidewall  318   b.    
     Lower inlet  320   b  and upper outlet  324   b  of housing  314   b  communicate respectively with axially distally opposite ends of aftertreatment element  312   b , namely lower inlet face  354   b  and upper outlet face  356   b . The housing has first and second housing sections  222   b  and  224   b  meeting at a joint  226   b  axially between axial ends  354   b  and  356   b  of aftertreatment element  312   b . Joint  226   b  is a service joint. Housing sections  222   b  and  224   b  are separable from each other at service joint  226   b  such that upon separation of housing sections  222   b  and  224   b , one of the axial ends  354   b  and  356   b  of the aftertreatment element is axially spaced beyond one of the separated housing sections  222   b  and  224   b , such that aftertreatment element  312   b  is readily accessible for ease of servicing, e.g. cleaning. During such servicing, aftertreatment element  312   b  will typically, though not necessarily, remain attached to one of the housing sections  222   b  or  224   b , e.g. by welding. A connection  232   b , comparable to above noted connection  232 , connects housing sections  222   b  and  224   b  to each other at service joint  226   b . In one form, the connection  232   b  is a band clamp known in the prior art, e.g. an inverted truncated V-shape band clamp, though other types of connections may be used, for example a bolted flange connection, or other typical arrangements for connecting housing or body sections, as above noted. In some embodiments, a gasket comparable to gasket  238  may be provided between the housing sections, as above. 
     In  FIG. 14 , housing section  222   b  is an outlet housing section. Aftertreatment element  312   b  extends axially into outlet housing section  222   b  along a first axial direction  240   b , and has an outlet axial end  356   b  within outlet housing section  222   b . Outlet housing section  222   b  has a sidewall  318   b  extending axially between first and second end walls  244   b  and  342   b  and of larger diameter than aftertreatment element  312   b  and providing an outlet plenum  250   b . End wall  244   b  of outlet housing section  222   b  is axially spaced from outlet axial end  356   b  of aftertreatment element  312   b  along the noted first axial direction  240   b . End wall  342   b  of outlet housing section  222   b  is axially spaced from outlet axial end  356   b  of aftertreatment element  312   b  along a second axial direction  252   b , which second axial direction  252   b  is opposite to the noted first axial direction  240   b . Sidewall  318   b  of outlet housing section  222   b  has a first span  258   b  extending from end wall  244   b  to a midpoint  260   b  radially aligned with outlet axial end  356   b  of aftertreatment element  312   b . Sidewall  318   b  has a second span  262   b  extending from midpoint  260   b  axially along the noted second axial direction  252   b  to end wall  342   b . Span  258   b  and end wall  244   b  define an open volume first plenum section  264   b  at outlet axial end  356   b  of aftertreatment element  312   b  and extending axially along the noted first axial direction  240   b  therefrom and which may include dome cap  330   b  extending thereacross to also define plenum  352   b . Span  262   b  and end wall  342   b  define an annular volume second plenum section  266   b  at outlet axial end  356   b  of aftertreatment element  312   b  and extending axially along the noted second axial direction  252   b  therefrom and in circumscribing relation to aftertreatment element  312   b . The noted second end wall is provided by the noted lower flange  342   b  spanning and closing annular volume plenum section  266   b  and annular space  328   b  to form collection space  344   b  for the water as diverted at  334   b . The noted one or more drain holes  338   b  and/or  339   b  are formed through at least one of lower flange  342   b  and housing sidewall  318   b . In one embodiment, the axial length of second span  262   b  may be greater than the axial length of first span  258   b  to reduce and save space at outlet axial end  356   b  of aftertreatment element  312   b  along the noted first axial direction  240   b  therefrom and reduce the amount of axial extension of housing  314   b  in the noted first axial direction  240   b  beyond outlet axial end  356   b  of aftertreatment element  312   b . In the preferred embodiment, sidewall  318   b  of outlet housing section  222   b  is of larger diameter than housing section  224   b.    
     In  FIG. 14 , a perforated tube  346   b , having perforations as shown at  348   b , extends axially in the housing between lower flange  342   b  and dome cap  330   b  and through which exhaust flows radially outwardly through perforations  348   b . Perforated tube  346   b  is in annular space  328   b  and annular volume plenum  266   b  and is radially between aftertreatment element  312   b  and housing sidewall  318   b . Dome cap  330   b  is axially spaced above aftertreatment element  312   b  by a first axial gap  350   b , and is axially spaced below upper outlet  324   b  by a second axial gap  352   b . Aftertreatment element  312   b  has the noted inlet face  354   b  facing axially downwardly, and has the noted outlet face  356   b  facing axially upwardly toward dome cap  330   b  and axially spaced therebelow by axial gap  350   b . Perforated tube  346   b  divides annular space  328   b  into a first annular subspace  356   b  and a second annular subspace  358   b . Perforated tube  346   b  is spaced radially outwardly of aftertreatment element  312   b  by first annular subspace  356   b  therebetween. Housing sidewall  318   b  is radially spaced outwardly of perforated tube  346   b  by second annular subspace  358   b  therebetween. 
     The system provides a method for servicing a combination exhaust muffler and aftertreatment element and water trap assembly comprising providing a joint as a service joint, as noted, at a location axially between the axial ends  356   b  and  354   b  of the aftertreatment element  312   b , and separating the housing sections  222   b  and  224   b  from each other at the service joint  226   b , such that upon separation of the noted housing sections, one of the axial ends  356   b ,  354   b  of the aftertreatment element  312   b  is axially spaced beyond one of the housing sections  224   b ,  222   b , and then servicing the aftertreatment element  312   b . The system also provides a method for saving space in a combination exhaust muffler and aftertreatment element and water trap assembly comprising providing an outlet housing section  222   b  wherein the aftertreatment element  312   b  extends axially into such outlet housing section  222   b , with the outlet axial end  356   b  of the aftertreatment element  312   b  being within outlet housing section  222   b , and providing the outlet housing section  222   b  with a sidewall  318   b  extending axially between first and second end walls  244   b  and  342   b  and of larger diameter than aftertreatment element  312   b  and providing an outlet plenum  350   b  of reduced axial extension along the noted first axial direction  240   b  from the outlet axial end  356   b  of the aftertreatment element  312   b . The method further involves providing the joint  226   b  at a location between the axial ends  356   b  and  354   b  of the aftertreatment element  312   b . The method further involves spacing the first end wall  244   b  of the outlet housing section  222   b  axially from the outlet axial end  356   b  of the aftertreatment element  312   b  along the noted first axial direction  240   b , spacing the second end wall  342   b  of the outlet housing section  222   b  axially from the outlet axial end  356   b  of the aftertreatment element  312   b  along the noted second axial direction  252   b , providing the sidewall  218   b  of the outlet housing section  222   b  with a first span  258   b  extending from the first end wall  244   b  along the noted second axial direction  252   b  to a midpoint  260   b  radially aligned with the outlet axial end  356   b  of the aftertreatment element  312   b , providing the sidewall  318   b  of the outlet housing section  222   b  with a second span  262   b  extending from the midpoint  260   b  axially along the noted second axial direction  252   b  to the noted second end wall  342   b , providing the first span  258   b  and the first end wall  244   b  defining an open volume first plenum section at the outlet axial end  256   b  of the aftertreatment element  312   b  and extending axially along the noted first axial direction  240   b  therefrom, providing the second span  262   b  and the second end wall  342   b  defining an annular volume second plenum section at the outlet axial end  356   b  of the aftertreatment element  312   b  and extending axially along the noted second axial direction  252   b  therefrom and in circumscribing relation to the aftertreatment element  312   b . The method further involves optionally providing the second span  262   b  of greater axial length than the first span  258   b  to reduce and further save space at the outlet axial end  356   b  of the aftertreatment element  312   b  along the noted first axial direction  240   b  therefrom and further reduce the amount of axial extension of the housing  314   b  in the noted first axial direction  240   b  beyond the outlet axial end  356   b  of the aftertreatment element  312   b.    
     It is recognized that various equivalents, alternatives and modifications are possible within the scope of the appended claims.