Mounting arrangement for a reducing agent injector

Abstract

An engine exhaust arrangement comprising: a curved exhaust pipe with an exhaust flow (12) from an upstream end to a downstream end; a fastening arrangement located in a curved section of the curved exhaust pipe and forming a recess in the curvature that extends into the curved exhaust pipe with a depth ofa downstream wall (86) extending at least partially into the curved exhaust pipe and arranged in the exhaust flow (12), coupled to and arranged downstream of the upstream wall (88), wherein the downstream wall (86) has an inner surface (160) oriented to substantially point towards the downstream end of the exhaust pipe and further having an outer surface (162) oriented substantially away from the downstream end of the exhaust pipe; and a recess (164) extending from the downstream wall (86) in a direction away from the downstream end of the exhaust pipe; and a recess opening (166) formed in the recess (164); and an injector (18) coupled to the outer surface (162) of the downstream wall and with a nozzle (150) aligned with the recess opening (166).

Description

Technical FieldThe present disclosure relates generally to engine exhaust aftertreatment systems, and more particularly to mounting arrangements for reductant injectors.A selective catalytic reduction (SCR) system may be used in an exhaust treatment system or an aftertreatment system to remove or reduce oxides of nitrogen (Noxor NO) emissions originating from exhaust gas from an engine. SCR systems often include an injector for spraying a reductant such as urea into the exhaust flow.The injector is typically positioned such that the reductant is sprayed toward a center of the exhaust flow such that the reductant is sufficiently mixed with the exhaust flow and does not impinge upon the walls of the exhaust piping. In certain exhaust pipe configurations, it may be advantageous to locate the injector within the exhaust pipe shroud to direct the reductant along the desired path. For example, US 2011 / 0 079 003 A1 issued to Sun et al. shows a recess attachment for a reductant injector that can be used with a curved exhaust pipe. A recess is provided which projects into the exhaust pipe. The recess has a wall capable of supporting the injector with an orientation that induces reductant flow in the desired direction. Although the depression disclosed by Sun et al. allows the injector to be positioned at a desired position within the exhaust pipe shroud, the injector is more directly exposed to the high temperatures of the exhaust flow. The placement of the tip matched with the well plate as shown in Sun et al. can cook the reductant and form deposits in the tip that restrict reductant flow. In addition, the higher thermal environment within the exhaust pipe shroud may adversely affect the components of the injector, the components made of materials designed for lower temperatures. Removing the tip away from the exhaust flow, as shown in U.S. Pat. No. 7,971,428 B2 to Kimuro et al., can reduce exposure of the injector to higher temperatures, but can also introduce recirculation flow that directs droplets of reductant back to the tip, which in turn can form deposits that block the injector nozzle.Furthermore, DE 11 2009 002 539 B4 shows a removable reducing agent decomposition reactor with integrated mixer, including a reducing agent injector receptacle which is formed by a casting method. In addition, WO 2011 / 030 064 A1 shows an exhaust system of a motor vehicle with a reactant injector. CUMMINS engines: 2010 Cummins Aftertreatment System Animation (URL: https: / / www.youtube.com / watch?v=p8cIK9qHClk) discloses a basic engine with cooled EGR, together with an exhaust aftertreatment system that reduces nitrogen oxides and particulate matter. US 2010 / 0 098 604 A1 teaches a removable reducing agent decomposition reactor with integrated mixer for use in exhaust systems. Furthermore, WO 2008 / 121 319 A2 shows a reducing agent supply unit with a solenoid fluid injector upstream of a catalyst for a selective catalytic reduction (SCR) aftertreatment in vehicles. In addition, KAISER, R.; RUSCH, K.: "Design of SCR systems for nitrogen oxide reduction in diesel engines"; in MTZ 12 / 2007, pp. 1062-1070 (2007), virtual designs of mixer systems by means of CFD simulation are disclosed.The present invention is directed to overcoming one or more of the problems or disadvantages associated with the prior art.SUMMARY OF THE DISCLOSUREThe object of the present invention is achieved by an engine exhaust arrangement according to claim 1. The dependent claims relate to preferred embodiments of the invention.According to one aspect of the disclosure, an engine exhaust assembly is provided having a curved exhaust conduit with exhaust flow from an upstream end to a downstream end. An attachment assembly comprising an upstream wall extending at least partially into the exhaust conduit and disposed in the exhaust stream, the attachment assembly further comprising a downstream wall coupled to and disposed downstream of the upstream wall, the downstream wall extending at least partially into the exhaust conduit and disposed in the exhaust stream, the downstream wall having an inner surface oriented to substantially point toward the downstream end of the exhaust conduits and further comprising an outer surface directed substantially away from the downstream end of the exhaust conduit. A recess extends from the downstream wall in a direction away from the downstream end of the exhaust conduit, and a recess opening is formed in the recess. An injector is coupled to the outer surface of the downstream wall and further includes a nozzle aligned with the cavity opening.According to another aspect of the disclosure, which may be combined with any of these aspects, the recess has an outer periphery having a substantially oval shape.According to another aspect of the disclosure that may be combined with any of these aspects, the exhaust conduit further includes a straight portion coupled to the downstream end of the curved portion and defining a straight portion centerline and the recess opening defining a recess centerline oriented at an angle with respect to the straight portion centerline.According to another aspect of the disclosure, which may be combined with any of these aspects, the injector has a plurality of feet and the downstream wall includes a plurality of protrusions, each protrusion extending toward a respective foot.According to another aspect of the disclosure, which may be combined with any of these aspects, a seal is disposed between the plurality of feet and the plurality of protrusions.According to another aspect of the disclosure, which may be combined with any of these aspects, the seal includes a mounting aperture for each injector foot and a seal aperture substantially aligned with the recess aperture.According to another aspect of the disclosure that may be combined with any of these aspects, the downstream wall defines an outer surface and the downstream wall defines an outer surface, wherein the injector mounting assembly further comprises an insulation layer configured to substantially cover the outer surface of the downstream wall and the outer surface of the downstream wall.According to another aspect of the disclosure that may be combined with any of these aspects, the downstream wall defines an outer surface in which at least one fin protrudes from the outer surface of the downstream wall.According to another aspect of the disclosure, which may be combined with any of these aspects, the injector is coupled to the downstream wall by a removable fastener. According to another aspect of the disclosure that may be combined with any of these aspects, the injector includes a plurality of feet and the downstream wall includes a plurality of protrusions, each protrusion extending to a respective foot, the engine drain assembly further including a seal disposed between the plurality of feet and the plurality of protrusions.Brief Description of the DrawingsFIG. 1 is a schematic view of an aftertreatment system. FIG. 2 is an enlarged schematic view of a curved exhaust pipe used in the exhaust system of FIG. 1. FIG. 3 is a side view, in cross section, of the curved exhaust pipe of FIG. 2. FIG. 4 is a side view, in cross-section, of the curved exhaust pipe of FIG. 2, showing an exhaust flow and a reductant jet. FIG. 5 is an enlarged side view, in cross section, of an injector coupled to an injector mounting assembly provided in the curved exhaust pipe. FIG. 6 is an enlarged side view, in section, of an injection mounting assembly of FIG. 5. FIG. 7 is an exploded view of the injector and the injector mounting assembly of FIG. 5. FIG. 8 is a front view of the injection mounting assembly of FIG. 5. FIG. 9 is a side view, in cross-section, of an alternative embodiment of the injection mounting assembly. FIG. 10 is a side view, in cross-section, of an alternative embodiment of an injector mounting assembly.Detailed DescriptionEmbodiments of a mounting arrangement are disclosed for use with a reductant injector for an engine exhaust aftertreatment system. In the exemplary embodiments described herein, the engine exhaust aftertreatment system includes a curved exhaust pipe in which the mounting arrangement is disposed. The mounting arrangement includes a recess for reducing exposure of the injector to elevated temperatures as associated with the exhaust flow. This recess may be shaped to minimize recirculation flows back to the injector, thereby reducing or eliminating reductant deposits. Additional features are disclosed for protecting the injector and related components from exposure to high temperature.In an exemplary embodiment illustrated in FIG. 1, an aftertreatment system receives an exhaust flow or flow 12 from an engine or power system. The engine may be any type of engine (an internal combustion engine, a gas engine, a diesel engine, a gaseous fuel or natural gas or propane engine, etc.) and may be any size with any number of cylinders, with any configuration (V, bank, radial, etc.). The engine may be used to power any machine or other device, including trucks or vehicles, off-road trucks or machines, earthmoving equipment, generators, aerospace applications, locomotive applications, marine applications, pumps, stationary equipment, or other engine powered applications.The aftertreatment system 10 includes an SCR catalyst 14 and a reductant system 16. The SCR catalyst 14 includes a catalyst material disposed on a substrate. The catalyst material is configured to reduce an amount of NOx in the exhaust flow 12 by using a reducing agent (reductant) 19. The substrate may have a plurality of channels therethrough and may form a honeycomb structure. An ammonium oxidation catalyst (AMOX) may also be provided downstream of the SCR 14 or zone coated at the end of the SCR 14.The reductant system 16 includes an injector 18 that introduces a reductant 19 into the exhaust flow 12. The injector 18 may include springs, washers, cooling channels, injector pins, and other elements not shown. Although other reductants 19 are possible, urea is the most common source of reductant 19. urea reductant 19 decomposes into ammonia (NH3) that is adsorbed or stored in the SCR catalyst 14.The exhaust flow 12 is introduced into the SCR catalyst 14 via an exhaust pipe or conduit 20. The exhaust pipe 20 has a straight portion 22 and a curved portion or bend 24 upstream of the straight portion 22. The length of the linear portion 22, or the distance between the injector 18 and the SCR catalyst 14, may be sufficiently long to mix the reductant 19 into the exhaust flow 12 and provide a sufficient residence time for the urea reductant 19 to convert to NH3.The exhaust aftertreatment system 10 may also include a diesel oxidation catalyst (DOC) 26, a diesel particulate filter (DPF=diene particulate filter) 28, and a purification catalyst or other exhaust treatment devices upstream or downstream of the SCR catalyst 14.The aftertreatment system 10 may also include a heat source 30 to regenerate the DPF 28. The heat source 30 may be formed by a burner including a combustion head and a housing to contain a flame. The heat source 30 may also be embodied by an electrical heating element, microwave device, or other heat source. The heat may also be generated by injecting a hydrocarbon source, such as fuel, into the exhaust flow 12, which fuel reacts with the DOC 26. The heat source 30 may also embody operation of the engine under conditions for producing elevated temperatures of the exhaust flow 12.DOC 26 and DPF 28 may be housed within a common first canister 32. DOC 26 and DPF 28 may also be housed in separate canisters. The SCR catalyst 14 may be housed within a second canister 34. The heat source 30, the first canister 32, and the second canister 34 may be disposed side by side in a parallel orientation on a mount 36. The heat source 30, the first canister 32, and the second canister 34 may also be arranged and fixed in other ways.The exhaust pipe 20 may also include a second bend 38 downstream of the rectilinear portion 22 to direct exhaust flow 12 into the second canister 34. In other embodiments, the second bend 38 may not be included and the second canister 34 may be aligned with the rectilinear portion 22. The first and second canisters 32 and 34 may also have ends 40 to provide and receive the exhaust flow 12.An inlet pipe 42 directs the exhaust flow 12 to the exhaust aftertreatment system 10. the second canister 34 or other end canister may have an outlet port 44 for the exhaust flow 12 to exit the aftertreatment system. An additional portion of the exhaust pipe (not shown) may direct the exhaust flow 12 from the heating source 30 to the receiving end 40 of the first canister 32. In other embodiments, the heat source 30 may not be provided and the entering tube 42 may direct the exhaust flow 12 to the receiving end 40 of the first canister 32.The exhaust flow 12 passes through the inlet pipe 42 and next, if present, through the heating source 30 in a first direction 46. The exhaust flow 12 passes through DOC 26, DPF 28, end 40, and through the bend 24. next, the exhaust flow 12 passes through the rectilinear portion 22 in a third direction 50, which may be parallel to the second direction 48. next, the exhaust flow 12 is directed for passage through the second bend 38 and through the second canister 34 in a fourth direction 52, which may be parallel to the second direction 48. finally, the exhaust flow 12 exits through the exit port 44.The reductant system 16 may also include a reductant source 54, a pump 56, and a valve 57. the reductant 19 is drawn from the reductant source 54 via the pump 56 and provided to an inlet connection 58 of the injector 18. The valve 57 or pump 56 may be used to control the delivery of the reductant 19. A controller and sensors may be provided to control the reductant system 16. The controller and sensors may control the heat source 30. The controller may also be in communication with an engine control module (ECM=engine control module) or may be included by the ECM.Reductant system 16 may also include a coolant source 60 that delivers coolant 62 to injector 18 via coolant connection joints 64. coolant source 60 may embody the engine cooling system or may be another coolant source 60. The coolant 62 may also be used to cool other portions of the reduction system 16 or the aftertreatment system 10.As best seen in FIG. 4, the injector 18 delivers a spray 68 of reductant 19 into the exhaust flow 12. If there is no influence by the exhaust gas flow 12, the axis of symmetry 70 can run substantially parallel to the third direction 50.As best seen in FIG. 2, the flexure 24 includes a flexure inlet end 72, a flexure outlet end 74, a flexure outer curve 76, a flexure inner curve 78, and flexure sides 80. The bend outer curve 76, the bend inner curve 80, the bend outer curve 76, the bend inner curve 78, and the bend sides 80 form a bend tube or box structure having an open bend inlet end 72 and a bend outlet end 74, The bend inlet end 72 is connected to and in fluid communication with the end 40 of the first canister 32, The bend outlet end 74 is connected to and in fluid communication with the rectilinear portion 22. As can be seen in FIGS. 3 and 4, the bend 24 can also have double walls 82 outside these walls. The double walls 82 provide thermal protection against the exhaust flow 12.An injector mounting assembly 84, such as a recess, is included in the flexure outer curve 76. The injector mounting assembly 84 is defined by or includes a downstream wall 86, an upstream wall 88, and side walls 90 which together form a recess pocket or region in the bend 24. The injector mounting assembly 82 may have a rounded triangular shape with a width at the upstream end that is greater than a width at the downstream end. The injector mounting assembly 84 may also have other shapes, including rectangular, cylindrical, or hemispherical.The straight portion 22 has an upstream end 92, an upstream end 94, an outer wall 96, an inner wall 98, and sides 100 to form a tubular tube or conduit. The rectilinear portion 22 and other components may be wrapped in insulation 102. The upstream end 92 connects to the outlet bent end 74. Dimensional aspects of the flexure 24 and injector mounting assembly 84 are best seen in FIGS. 2 and 3. FIG. 2 shows the flexure 24 having an inlet width 101 and an outlet width 103. The width of the bend 24 may decrease from the bend inlet end 72 to the bend outlet end 74, resulting in a smaller outlet width 103 compared to the inlet width 101. As can be seen in FIG. 3, the bend 24 has an inlet depth and an outlet depth 106. The depth of the bend 24 may gradually increase from the bend inlet end 72 to the bend outlet end 74, resulting in a greater outlet depth 106 than that of the inlet depth 104. Since the relative sizes of the inlet width 101 to the outlet width 103 and the inlet depth 104 to the outlet depth 106 vary in opposite relationship, a substantially constant flow area can be maintained. In other embodiments, the width and depth of the bend 24 may be constant or may vary in different ways. The outlet depth 106 and the outlet width 103 can be substantially adapted to the width or the diameter of the rectilinear part 22.A centerline 108 shown in FIG. 3 extends through the center of the bend 24 and may continue through the straight portion 22. The injector mounting assembly 84 extends into the bend 24 and has a maximum bend extension point 110. The maximum bend extension point 110 may be a point or line where the downstream wall 86 and the upstream wall 88 meet. A curved center plane 112 extends through the maximum bending extension point 110 and is normal to the center line 108. A projected outer curve 114 extends in space above the injector mount assembly 84 along the same curvature as the bend outer curve 76. a projected center depth 116 represents a center depth of the bend 24 when the injector mount assembly 84 is not present. This projected center depth 116 is the depth of the bend 24 along the bend center plane 112 from the inner curve 78 through the maximum bend extension point 110 to the projected outer curve 114.A minimum center depth 118 represents a center depth of the bend 24 where it is narrowest due to the injector mounting arrangement 84. This minimum center depth 118 is the depth of the bend 24 along the bend plane 112 from the bend inner curve 78 to the maximum bend extension point 110. A cavity maximum extension length 120 represents the maximum depth of the injector mount assembly 84.The injector mounting assembly 84 has a downstream wall length 122 and a downstream wall length 124. The downstream wall length 122 is the length that extends along the downstream wall 86 from the outer curve 76 to the maximum bend extension point 110. The upstream wall length 124 is the length that extends along the upstream wall 88 from the outer curve 76 to the maximum bend extension point or extension point 110. Although many of the dimensions given above are given as minimum and maximum, projections and other additional structures should not be considered to be encompassed by these dimensions.FIG. 4 shows the direction of the exhaust flow 12 as it passes through the bend 24 into the straight portion 22. The flow direction includes a straight inlet device 126, a straight outlet direction 128, and a middle curved direction between the straight inlet direction 26 and the straight outlet direction 28. Also included are blocked flows 132 below the upstream wall 88 of the injector mount assembly 84. dead flows 134 exist downstream of the downstream wall 86 and in the corner where the downstream wall 86 meets the outer curve 76.The injector 18 may be mounted in the downstream wall 86 such that the reductant jet 68 is aligned with the axis of symmetry 70 and the centerline 108 when extending in the straight portion 22. The injector mounting assembly 84 may also be sized such that the axis of symmetry 70 is arranged to intersect with an intermediate direction 136 of the exhaust flow 12. the intermediate direction 136 is the direction of the exhaust flow 12 when it begins to straighten in the straight discharge direction 128 from the central curved or curved direction 130. The intermediate direction 136 is the first exhaust flow 12 intersecting the axis of symmetry 70 that is not blocked by the upstream wall 88.As best shown in FIGS. 5 and 7, a front end of the injector 18 may include a nozzle 150 for discharging the reducing agent. The forward end of the injector 18 may further include a plurality of feet 152 that allow the injector 18 to be removably or detachably coupled to the injector mounting assembly 84 using washers 153 and fasteners 154. The feet 152 may terminate at a plane that is adjacent to the nozzle 150.The reductant inlet connection 58 is positioned opposite the nozzle 150 at a rear end of the injector. The rear end of the injector 18 may also include coolant port connections 64. A thermal shield 156 is coupled to the injector and has a bottom 158 that extends below the coolant port connections 64.The injector mounting assembly 84 may be configured to protect the injector 18 from high temperature exhaust flow, minimizing recirculation flow, and thereby preventing the formation of deposits of reductants. As best seen in Figs. 5-8, the downstream wall 86 has an inner surface 160 facing the outlet curved end 74, and further an opposing outer surface 162. A recess 164 is formed in the downstream wall 86 extending away from the bend outlet end 174, and an opening 166 is formed in the center of the recess 164 for fluid communication with the injector nozzle 150.In an exemplary embodiment, the recess 164 is shaped to reduce recirculation flow. As best seen in FIG. 8, the recess 164 has an outer periphery 168 having a substantially oval shape, although other peripheral shapes may be used. A cavity wall 170 may therefore have a generally frustoconical shape extending about a centerline 172 of the opening 166. The cavity wall 170 is further configured and oriented to reduce recirculation flow. The outer surfaces 162 of the injector mounting assembly 84 may include a plurality of mounting protrusions 180 positioned to abut the feet 152 of the injector 18. an optional seal 182 may be disposed between the feet 152 and the mounting protrusions 180 to further isolate the injector 18 from heat when coupled to the injector mounting assembly 84. As best seen in FIG. 7, the seal 182 may include a seal opening 184 substantially aligned with the recess opening 166 and a plurality of fastener openings 186 sized to receive the fasteners 154. The seal 182 may be formed of a material having a low thermal conductivity, such as vermiculite.Anchoring protrusions 190 may also protrude from outer surface 162 to provide structure for attaching an insulation layer 192 over outer surface 162 of downstream wall 86 and also an outer surface 194 of upstream wall 88. The insulating layer 192 may be formed of a thermally insulating material such as a silicate fiber mat enclosed with a stainless steel foil.The opening 166, and therefore the injector nozzle 150, may be positioned and oriented to promote the mixture of reductant with the exhaust flow 12 as it enters the straight portion 22. For example, in the illustrated embodiment, the center of the opening 166 is positioned above the straight portion of the centerline 108, and as best shown with the centerline extension 108a shown in FIG. 3. Additionally, the aperture 166 is oriented such that the aperture centerline 172 forms an angle 174 with respect to the rectilinear portion of the centerline 108. For example, the center of the opening 166 may be approximately 10 millimeters above the centerline extension 108 and the opening centerline 172 may extend at an angle of approximately 5° with respect to the rectilinear portion of the centerline 108. With the opening 166 positioned and oriented in this manner, the spray of reductant will be better centered within the straight portion 22, thereby increasing the mixture of reductant and the exhaust flow or exhaust flow.In an alternative embodiment, shown in FIG. 9, an injector mounting assembly 200 includes a well plate 202 and a separate adapter 204. The adapter 204 may be coupled to the well plate 202, for example, by welding. The adapter 204 defines a recess 206 similar to the recess 164 described above. The recess 206 is in fluid communication via an opening 208 formed in the well plate 202.In another alternative embodiment, illustrated in FIG. 10, an injector mounting assembly 220 is modified to conduct high temperature heat away from the injector 18. Specifically, the injector mounting assembly includes a downstream wall 222 having an outer surface 224 formed with at least one fin 226. Heat will flow through the mass additionally provided by fin 226, thereby conducting the heat away from injector 18.Industrial applicabilityReductant jets or sprays 68 often form deposits in the exhaust aftertreatment system 10. Deposits may be formed when the urea reductant 19 is not rapidly broken down into NH3and thick layers of urea reductant 19 accumulate. These layers may build up when more and more urea reducing agent 19 is sprayed or collected, and this may have a cooling effect that prevents decomposition into NH3. As a result, the urea reductant 19 sublimes into crystals or otherwise transforms into a solid composition to form the deposit. This composition may consist of bi-urea (NH2CONHCONH2) or cyanurea ((NHCO) 3) or another composition depending on the temperatures and other conditions.While the reductant system 16 may or may not be air assisted, deposits develop more quickly in airless reductant systems 16.Airless reductant systems 16 tend to produce reductant sprays or jets 68 having a larger droplet size than air assisted reductant systems 16. Generally, these deposits may form on surfaces of aftertreatment system 10 where reductant spray 68 impinges, recirculates, or deposits. For example, the deposits may form on the outer wall 96 or around the outlet 96.These deposits may be negative factors affecting the operation of the system. The deposits may block the exhaust flow 12, may cause higher backpressure, and may reduce the performance of the engine and aftertreatment system 10, as well as the efficiency thereof. The deposits may also disrupt the flow and mixing of the urea reductant 19 into the exhaust flow 12 and thereby reduce the decomposition into NH3and reduce the NOxreduction efficiency. The deposits may also block the injector or interrupt the reductant spray 68. The formation of the deposits also consumes urea reductant 19, making injection control more difficult and possibly reducing NOx reduction efficiency in the SCR 14. The deposits may also corrode components of the aftertreatment system 10 and degrade the structural and thermal properties of the SCR catalyst. The deposits may further block the channels of the SCR catalyst 14, which in turn reduces NOx reduction efficiency.The injector mounting assembly 84 may help prevent overheating of the injector tip by removing the injector 18 from direct contact with the exhaust flow, with the recess 164 configured to reduce or eliminate recirculation flow back to the injector nozzle 150. The recess 164 displaces the injector 18 by a recess distance such as approximately 12 to 25 millimeters, thereby reducing heat to the injector tip due to exposure of the injector to a high temperature exhaust flow. Additionally, the recess 164 is configured and oriented to minimize recirculation flow and prevent reductant deposits associated therewith. Additional measures such as the isolation layer 192 and the seal 182 provide additional thermal isolations for the injector 18.It will be appreciated that the foregoing description provides examples of the disclosed arrangement and technique. However, it is contemplated that other implementations of the disclosure may differ in detail from the examples above. All references to the disclosure or examples thereof are intended to be references to the specific example discussed at this point and there is no intention to provide any limitation on the scope of the disclosure in general. Language distinctions regarding certain features are not intended to provide a lack of preference for those features, but do not completely exclude such features from the scope unless otherwise stated.The denomination of ranges of values is only for brief reference in detail to each distinct value in a range unless otherwise stated, and each distinct value is incorporated into the specification as if set forth therein. All methods described herein may be performed in any suitable order unless otherwise indicated herein or clearly contradicted by context.

Claims

An engine exhaust assembly comprising: a curved exhaust conduit having an exhaust flow (12) from an upstream end to a downstream end; a mounting arrangement disposed in a curved portion of the curved exhaust conduit and forming a depression in the curvature that extends a depth into the curved exhaust conduit, the mounting arrangement comprising: an upstream wall (88) that extends at least partially into the curved exhaust conduit and is disposed in the exhaust flow (12); a downstream wall (86) extending at least partially into the curved exhaust conduit and disposed in the exhaust flow (12) coupled to and disposed downstream of the upstream wall (88), the downstream wall (86) having an inner surface (160) oriented to substantially face the downstream end of the exhaust conduit and further having an outer surface (162) facing substantially away from the downstream end of the exhaust conduit; and a recess (164) extending from the downstream wall (86) in a direction away from the downstream end of the exhaust conduit; and a recess opening (166) formed in the recess (164); and an injector (18) coupled to the outer surface (162) of the downstream wall and having a nozzle (150) aligned with the recess opening (166).An engine exhaust assembly according to claim 1, wherein the recess (164) has an outer periphery (168) having a substantially oval shape.An engine exhaust assembly according to claim 1, further comprising a straight exhaust conduit (22) coupled to the downstream end of the curved exhaust conduit and defining an exhaust conduit straight centerline (108), and wherein the recess opening (166) defines a recess centerline (172) oriented at an angle with respect to the exhaust conduit straight centerline (108a).An engine exhaust assembly as claimed in claim 1, wherein the injector (18) includes a plurality of feet (152) and wherein the downstream wall (86) includes a plurality of protrusions (180), each protrusion (180) extending to a respective foot (152).An engine exhaust assembly according to claim 4, further comprising a seal (182) disposed between the plurality of feet (152) and the plurality of protrusions (180).An engine exhaust assembly as claimed in claim 5, wherein the seal (182) includes a mounting aperture (186) for each injector foot (152) and a seal aperture (184) substantially aligned with the recess aperture (166).An engine exhaust assembly according to claim 1, wherein the upstream wall (88) defines an outer surface (194), and wherein the mounting assembly further comprises an insulation layer (102) configured to substantially cover the outer surface (194) of the upstream wall and the outer surface (162) of the downstream wall.An engine exhaust assembly according to claim 1, wherein the injector (18) is coupled to the downstream wall (80) by a removable fastener (154).

Images