Mixer used in aftertreatment system

Abstract

The invention relates to a mixer for use in an aftertreatment system. An aftertreatment system includes: a housing; and the SCR system is arranged in the shell. The mixer is disposed upstream of the SCR system and includes: a hub; a tubular member disposed circumferentially around the hub and defining a reductant inlet port; and a plurality of blades extending from the hub to the tubular member such that an opening is defined between adjacent blades. The plurality of vanes swirl exhaust gas in the circumferential direction. A reductant injector is disposed on the housing upstream of the SCR system along the transverse axis and is configured to add reductant through the reductant inlet port into the exhaust gas flowing through the housing. The reducing agent is added opposite the circumferential direction at a non-zero angle relative to the transverse axis to achieve virtual interception. The mixer center axis is radially offset from a housing center axis of the housing.

Description

[0001] This application is a divisional application of an application with an application date of February 11, 2021, an application number of 202180016222.0, and an invention title of "Mixer for Use in a Post-treatment System".

[0002] Cross-reference to Related Applications

[0003] This application claims the benefit of U.S. Provisional Application No. 62 / 982,354, filed on February 27, 2020, the entire disclosure of which is hereby incorporated by reference. Technical Field

[0004] The present disclosure generally relates to post-treatment systems for use with internal combustion engines. Background

[0006] Exhaust after-treatment systems are used to receive and process exhaust generated by an engine, such as an internal combustion engine. Conventional exhaust after-treatment systems include any of several different components to reduce the level of harmful exhaust emissions present in the exhaust. For example, certain exhaust after-treatment systems for diesel-powered internal combustion engines include a selective catalytic reduction (SCR) system that includes an SCR catalyst that is formulated to convert NO 3 (certain proportions of NO and NO X ) to harmless nitrogen gas (N 2 ) and water vapor (H 2 ) in the presence of ammonia (NH 2 O).

[0007] Typically, a reductant, such as diesel exhaust fluid (e.g., an aqueous urea solution), is added to the after-treatment system as a source of ammonia. The reductant facilitates the decomposition of the components of the exhaust by the SCR catalyst. However, if the reductant is not substantially mixed with the exhaust, the added reductant may not fully decompose and cause the formation of reductant deposits on the walls or various components of the after-treatment system. Over time, the reductant deposits accumulate and cause a reduction in the SCR catalytic conversion efficiency (CE) of the SCR catalyst. To promote mixing, mixers or reductant injectors are used and installed to be offset from the flow axis of the exhaust. However, the formation of reductant deposits remains a challenge for after-treatment systems.

[0008] Summary

[0009] The embodiments described herein generally relate to a mixer for promoting the mixing of a reducing agent with the exhaust gas flowing through a post-treatment system and reducing the deposition of the reducing agent. Specifically, the embodiments described herein include a multi-vane mixer that includes a central hub that defines a flow passage radially offset from the longitudinal axis of the post-treatment housing, and the embodiments described herein include a reducing agent injector that injects the reducing agent at a non-zero angle relative to the transverse axis of the post-treatment system and in a circumferential direction opposite to the rotation of the exhaust gas caused by the mixer.

[0010] In some embodiments, a post-treatment system for treating the components of the exhaust gas generated by an engine includes: a housing that defines a housing central axis; a selective catalytic reduction (SCR) system disposed in the housing; a mixer disposed upstream of the SCR system in the housing, the mixer including a hub, a tubular member, and a plurality of vanes, the tubular member circumferentially disposed around the hub and defining a reducing agent inlet port, the plurality of vanes extending from the hub to the tubular member such that openings are defined between adjacent vanes of the plurality of vanes to allow the exhaust gas to flow through the openings, such that the plurality of vanes cause the exhaust gas to vortex in a circumferential direction relative to the exhaust gas flow path; and a reducing agent injector disposed on the housing upstream of the SCR system along the transverse axis of the housing and configured to inject the reducing agent into the exhaust gas flowing through the housing through the reducing agent inlet port, the reducing agent being injected at a non-zero angle relative to the transverse axis and in a direction opposite to the circumferential direction, wherein the mixer central axis defined by the hub is radially offset from the housing central axis at a position upstream of the mixer in the housing.

[0011] In some embodiments, the mixer central axis is horizontally offset from the housing central axis.

[0012] In some embodiments, the mixer central axis is vertically offset from the housing central axis.

[0013] In some embodiments, the non-zero angle is in the range of 5 degrees to 60 degrees relative to the transverse axis.

[0014] In some embodiments, an auxiliary opening is defined in the tubular member near the reducing agent inlet port.

[0015] In some embodiments, the housing defines a circular, square, rectangular, oval, elliptical, or polygonal cross-section.

[0016] In some embodiments, the mixer further includes a flange that extends radially outward from the edge of the upstream end of the tubular member and is fixed to the inner surface of the housing.

[0017] In some embodiments, the post-treatment system further includes: a blocking member extending from the hub to the tubular member.

[0018] In some embodiments, a plurality of vanes extend from a hub to a tubular member over a portion of the circumference of the tubular member between 130 degrees and 230 degrees.

[0019] In some embodiments, a plurality of through-holes are defined through a barrier member.

[0020] In some embodiments, a slit is defined through at least one of the plurality of vanes.

[0021] In some embodiments, a component for a post-treatment system includes: a hub; a tubular member circumferentially disposed around the hub and defining a reductant inlet port; and a plurality of vanes extending from the hub to the tubular member such that an opening is defined between adjacent vanes of the plurality of vanes to allow exhaust gas to flow through the opening, whereby the plurality of vanes cause the exhaust gas to vortex in a circumferential direction relative to an exhaust gas flow path of the exhaust gas, a mixer central axis defined through the hub is configured to be radially offset relative to a housing central axis of a housing within which the mixer can be positioned at a location upstream of the mixer, wherein the reductant inlet port is axially aligned with a central portion of the exhaust gas flow path and is configured to allow the reductant to be introduced at a non-zero angle relative to the central portion in a direction opposite to the circumferential direction.

[0022] In some embodiments, a mixer for a post-treatment system includes: a hub; a tubular member circumferentially disposed around the hub and defining a reductant inlet port; and a plurality of vanes extending from the hub to the tubular member such that an opening is defined between adjacent vanes of the plurality of vanes to allow exhaust gas to flow through the opening, such that the plurality of vanes cause the exhaust gas to vortex in a circumferential direction relative to an exhaust gas flow path of the exhaust gas, a mixer central axis defined through the hub is configured to be radially offset relative to a housing central axis of a housing within which the mixer can be positioned at a location upstream of the mixer; wherein the reductant inlet port is axially aligned with a central portion of the exhaust gas flow path and is configured to allow the reductant to be introduced at a non-zero angle relative to the central portion in a direction opposite to the circumferential direction.

[0023] In some embodiments, the mixer central axis is horizontally offset from the housing central axis.

[0024] In some embodiments, the mixer central axis is vertically offset from the housing central axis.

[0025] In some embodiments, the non-zero angle is in the range of 5 degrees to 60 degrees relative to a transverse axis.

[0026] In some embodiments, an auxiliary opening is defined in the tubular member near the reductant inlet port.

[0027] In some embodiments, the assembly further includes: a blocking member extending from the hub to the tubular member.

[0028] In some embodiments, a plurality of vanes extend from the hub to the tubular member about a portion of the circumference of the tubular member between 130 degrees and 230 degrees.

[0029] In some embodiments, a plurality of through-holes are defined through the blocking member.

[0030] In some embodiments, a slit is defined by at least one of the plurality of vanes.

[0031] It should be appreciated that all combinations of the foregoing concepts and additional concepts discussed in greater detail below (provided that such concepts are not mutually inconsistent) are contemplated as being part of the subject matter disclosed herein. In particular, all combinations of claimed subject matter appearing in the present disclosure are contemplated as being part of the subject matter disclosed herein. Brief Description of the Drawings

[0033] The foregoing and other features of the present disclosure will become more apparent from the following description taken in conjunction with the accompanying drawings and the appended claims. It is to be understood that the drawings are only illustrative of several embodiments in accordance with the present disclosure and are therefore not to be considered as limiting its scope, and the present disclosure will be described with additional specificity and detail by use of the drawings.

[0034] Figure 1 is a schematic view of a post-treatment system according to one embodiment.

[0035] Figure 2 is along Figure 1 the A-A line in Figure 1 a front view cross-sectional view of the housing of the post-treatment system in

[0036] Figure 3 is a front view cross-sectional view of the housing of the post-treatment system along the A-A line in Figure 1 in Figure 1 according to another embodiment, showing the mixer disposed in the housing and the spray cone produced by the reductant injector mounted on the housing.

[0037] Figure 4 is a front view cross-sectional view of the housing of the post-treatment system along the A-A line in Figure 1 in Figure 1 according to yet another embodiment, showing the mixer disposed in the housing and the spray cone produced by the reductant injector mounted on the housing.

[0038] Figure 5 is along the A-A line in accordance with yet another embodimentFigure 1 taken along line A-A in Figure 1 front elevation sectional view of the housing of the aftertreatment system in

[0039] Figure 6 is Figure 5 front elevation perspective view of the mixer of

[0040] Figure 7 is a computational fluid dynamics (CFD) simulation showing the flow streamlines of the exhaust gas through Figure 6 the mixer of

[0041] Figure 8 front elevation perspective view of a mixer according to one embodiment.

[0042] Figure 9 side elevation perspective view of a mixer according to another embodiment.

[0043] Figure 10 is a schematic flow chart of a method for manufacturing an aftertreatment system according to one embodiment.

[0044] In all of the following detailed description, reference is made to the accompanying drawings. In the drawings, like reference numerals generally identify like components, unless the context dictates otherwise. The illustrative embodiments described in the detailed description, the drawings, and the claims are not meant to be limiting. Other embodiments may be used and other changes may be made without departing from the spirit or scope of the subject matter presented herein. It will be readily understood that the aspects of the present disclosure, as generally described and illustrated in the figures herein, can be arranged, substituted, combined, and designed in a variety of different configurations, all of which are explicitly contemplated and form part of the present disclosure. Detailed Description

[0046] The embodiments described herein generally relate to mixers for facilitating the mixing of a reducing agent with the exhaust gas flowing through an aftertreatment system and reducing reducing agent deposition. Specifically, the embodiments described herein include a multi-vane mixer and a reducing agent injector. The multi-vane mixer includes a central hub that defines a flow passage radially offset from the longitudinal axis of the aftertreatment housing. The reducing agent injector injects the reducing agent at a non-zero angle with respect to the transverse axis of the aftertreatment system, and the injection direction is opposite to the circumferential vortex direction of the exhaust gas induced by the mixer.

[0047] Reducing agent deposition is an important issue in the operation of aftertreatment systems. Reducing agent deposition can accumulate in the SCR system or other components of the aftertreatment system and cause a decrease in the SCR catalytic conversion efficiency (CE) of the SCR system and an increase in back pressure. Various mixers have been used to promote the mixing of the reducing agent with the exhaust gas to reduce reducing agent deposition. Other solutions have used reductant injectors that are asymmetrically mounted. However, due to the presence of flow recirculation in the cavity where the reductant injector is installed, such reductant injectors can increase the risk of forming reducing agent deposition at the tip of the reductant injector. In addition, when using a spray with a large cone angle, asymmetrically mounted reductant injection generally cannot avoid impinging on the wall of the port in which the reductant injector is installed without increasing the size of the reductant port. Increasing the size of the reductant port can increase the exhaust assist flow rate, i.e., the flow rate of the exhaust gas through the reductant port in a direction transverse to the main gas flow. This, in turn, can reduce the effect of the exhaust gas flow in the main stream intercepting the spray droplets, thereby promoting reductant mixing and reducing reductant deposition, since the larger flow rate of the exhaust gas entering the larger reductant port reduces the flow rate of the main stream and weakens the main stream.

[0048] In contrast, various embodiments of mixers for mixing a reducing agent with exhaust gas can provide one or more advantages, including, for example: (1) delivering a highly uniform flow and a highly uniform reducing agent distribution at the inlet of a downstream reductant injector; (2) reducing the pressure drop; (3) allowing dynamic control of the spatial distribution of reducing agent droplets under different operating conditions; (4) allowing integration of a wide reducing agent spray cone angle; and (5) reducing flow recirculation near the tip of the reductant injector, thereby reducing the risk of reducing agent deposition near the tip of a symmetrically mounted reductant injector and in the mixer and in the downstream SCR system.

[0049] Figure 1 is a schematic diagram of an aftertreatment system 100 according to one embodiment. The aftertreatment system 100 is configured to receive exhaust gas (e.g., diesel exhaust from an engine 10) and treat the components of the exhaust gas (e.g., particulate matter, NO X 、CO、CO 2 ). The aftertreatment system 100 includes a reductant storage tank 110, a reductant addition assembly 112, a mixer 120, and an SCR system 150, and may also include an oxidation catalyst 142 and a filter 144.

[0050] The engine 10 may include, for example, a diesel engine, a gasoline engine, a natural gas engine, a dual-fuel engine, a biodiesel engine, an E85 engine, or any other suitable engine. In some embodiments, the engine 10 includes a diesel engine. The engine 10 burns fuel and generates exhaust gas including NO X 、CO、CO 2 and other components.

[0051] The post-treatment system 100 includes a housing 101, and components of the post-treatment system 100 are disposed in the housing 101. The housing 101 can be formed of a rigid, heat-resistant, and corrosion-resistant material, such as stainless steel, iron, aluminum, metal, ceramic, or any other suitable material. The housing 101 can have any suitable cross-section, such as circular, square, rectangular, oval, elliptical, polygonal, or any other suitable shape. The housing 101 defines a housing central axis A L . In some embodiments, the housing 101 can have a circular cross-section and the housing central axis A L is an axis that longitudinally extends through the center point of the housing 101 (i.e., the point equidistant from the outer periphery of the housing 101). In other embodiments where the housing 101 has a non-circular cross-section (such as square, rectangular, oval, elliptical, polygonal, or any other suitable cross-section), the housing central axis A L is an axis that longitudinally extends through the geometric center or centroid of the cross-sectional shape defined by the housing 101 (i.e., the position of the arithmetic mean of all points in the cross-sectional shape defined by the housing 101).

[0052] The inlet conduit 102 is fluidly coupled to the inlet of the housing 101 and is configured to receive exhaust gas from the engine 10 and communicate the exhaust gas to the internal volume defined by the housing 101. Additionally, the outlet conduit 104 can be coupled to the outlet of the housing 101 and is configured to discharge the treated exhaust gas to the environment (e.g., exhaust gas that has been treated to remove particulate matter and / or reduce the components of the exhaust gas including, such as NO X gases, CO, unburned hydrocarbons, etc. generated by the SCR system 150).

[0053] The first sensor 103 can be positioned in the inlet conduit 102. The first sensor 103 can include a NO X sensor that is configured to measure the amount of NO X gas included in the exhaust gas flowing into the SCR system 150, and the first sensor 103 can include a physical sensor or a virtual sensor. In various embodiments, a temperature sensor, a pressure sensor, an oxygen sensor, or any other sensor can also be positioned in the inlet conduit 102 to determine one or more operating parameters of the exhaust gas flowing through the post-treatment system 100.

[0054] The second sensor 105 can be positioned in the outlet conduit 104. The second sensor 105 can include a second NO XA sensor configured to determine the amount of NOx gas emitted into the environment after passing through the SCR system 150. In other embodiments, the second sensor 105 may include a particulate matter sensor configured to determine the amount of particulate matter in the exhaust gas emitted into the environment. In other embodiments, the second sensor 105 may include an ammonia sensor configured to measure the amount of ammonia in the exhaust gas flowing out of the SCR system 150, i.e., to determine ammonia leakage. This can be used as a measure of the catalytic conversion efficiency of the SCR system 150, for adjusting the amount of reductant to be added to the SCR system 150, and / or for adjusting the temperature of the SCR system 150 to allow the SCR system 150 to effectively use ammonia to catalytically decompose the NO contained in the exhaust gas flowing through the SCR system X gas. In some embodiments, an ammonia oxidation (AMOX) catalyst may be located downstream of the SCR system 150 to decompose any unreacted ammonia in the exhaust gas downstream of the SCR system 150.

[0055] The aftertreatment system 100 may include various other components, such as an oxidation catalyst 142 (e.g., a diesel oxidation catalyst) located upstream of the SCR system 150, and the oxidation catalyst 142 is configured to decompose unburned hydrocarbons and / or CO contained in the exhaust gas. In some embodiments, a filter 144 may be disposed downstream of the oxidation catalyst and upstream of the SCR system 150 and is configured to remove particulate matter (e.g., soot, debris, inorganic particles, etc.) from the exhaust gas.

[0056] As described herein, the SCR system 150 is configured to decompose the components of the exhaust gas flowing through the SCR system in the presence of a reductant. In some embodiments, the SCR system 150 may include a selective catalytic reduction filter (SCRF). The SCR system 150 includes a catalyst configured to catalyze the decomposition of NO X gas. Any suitable catalyst may be used, for example, a catalyst based on platinum, palladium, rhodium, cerium, iron, manganese, copper, vanadium, any other suitable catalyst, or a combination thereof. The catalyst may be disposed on a suitable substrate, such as a ceramic (e.g., cordierite) or a metal (e.g., kanthal) monolithic core, which may, for example, define a honeycomb structure. A washcoat may also be used as the carrier material for the SCR system 150. Such a washcoat material may include, for example, alumina, titanium dioxide, silica, any other suitable washcoat material, or a combination thereof.

[0057] The reductant injector 156 is disposed on the housing 101 upstream of the SCR system 150 and is configured to inject the reductant into the exhaust gas flowing through the housing 101. The reductant injector 156 is symmetrically mounted on the side wall of the housing 101 so that the reductant injector 156 is mounted to be parallel to the transverse axis A of the housing 101. T Axially aligned, for example, installed in a reductant port defined in the housing 101, i.e. aligned with a central portion of an exhaust gas flow path of the exhaust gas flowing through the housing 101. As used herein, the term "lateral axis" means a direction of the housing 101 perpendicular to the housing center axis A of the housing 101. L In various implementations, the reductant injector 156 may include a nozzle having a predetermined diameter and configured to inject a spray cone SC of the reductant into the exhaust gas.

[0058] The reductant storage tank 110 is configured to store a reductant. The reductant is formulated to promote the removal of components of exhaust gas (such as NO X Any suitable reducing agent may be used. In some embodiments, the exhaust gas comprises diesel exhaust and the reducing agent comprises a diesel exhaust fluid. For example, the diesel exhaust fluid may comprise urea, an aqueous solution of urea, or any other fluid containing ammonia, a byproduct, or any other diesel exhaust fluid known in the art (e.g., For example, the reductant may include an aqueous urea solution having a specific ratio of urea to water. In some embodiments, the reductant may include an aqueous urea solution including 32.5% urea by mass and 67.5% deionized water by mass, including 40% urea by mass and 60% deionized water by mass, or any other suitable ratio of urea to deionized water.

[0059] The reductant addition assembly 112 is fluidly coupled to the reductant storage tank 110. The reductant addition assembly 112 is configured to selectively add reductant to the exhaust gas. The reductant addition assembly 112 may include various structures, such as pumps, valves, screens, filters, etc., to facilitate receiving reductant from the reductant storage tank 110 and delivering it to the SCR system 150.

[0060] The mixer 120 is disposed in the housing 101 upstream of the SCR system 150, near the reductant injector 156, and is configured to promote mixing of the reductant added by the reductant injector 156 with the exhaust gas. Figure 2 , the mixer 120 includes a hub 122. In some embodiments, the hub 122 can be solid. In other embodiments, the hub 122 can define a channel to allow a portion of the exhaust gas to flow therethrough.

[0061] The tubular member 124 is circumferentially disposed around the hub 122. The shape of the tubular member 124 can be cylindrical. The diameter of the outer tubular member 124 can be smaller than the diameter of the housing 101. The outer tubular member 124 can have a generally circular cross-section and define a generally linear exhaust flow path. In other embodiments, the outer tubular member 124 can have other cross-sectional shapes, and the gas flow path through the outer tubular member can be linear or non-linear. For example, the tubular member 124 can have a conical, frustoconical, aerodynamic or other shape. In some embodiments, the tubular member 124 is configured as a venturi. In these embodiments, the diameter of the tubular member 124 at its inlet can be larger than the diameter of the outlet of the tubular member 124.

[0062] A plurality of vanes 126 extend from the outer surface of the hub 122 to the tubular member 124 such that an opening 127 is defined between adjacent vanes 126 to allow the main streamlines of the exhaust gas to flow therethrough. In some embodiments, the plurality of vanes 126 can include an upstream set of vanes and a downstream set of vanes. The vanes 126 can be inclined at an angle (e.g., in the range of 10 degrees to 80 degrees) from the hub towards the tubular member 124 so as to induce vortices in the exhaust gas when the exhaust gas flows through the opening 127 in the circumferential direction A (e.g., clockwise direction) relative to the exhaust flow path. A flange 128 extends radially outward from the edge of the upstream end of the tubular member 124. The flange 128 can be fixed (e.g., welded, or coupled via screws, nuts, bolts, rivets, etc.) to the inner surface of the housing 101 to mount the mixer 120 in the housing 101.

[0063] In some embodiments, a blocking member 125 that blocks or otherwise impedes the exhaust flow extends around a portion of the gas flow path that is not covered by the portion around which the plurality of vanes 126 extend. In some embodiments where the mixer 120 includes an upstream set of vanes, the blocking member 125 can be located upstream of the reductant inlet port 131, on the side of the mixer 120 where the reductant inlet port 131 is located. As Figure 2 shown, the blocking member 125 can include a wall extending from the hub 122. In other embodiments, the blocking member 125 can be a component separate from the plurality of vanes 126. In some embodiments, the vanes 126 can extend around a portion of the circumference of the tubular member 124 between 130° and 230°. In other embodiments, the vanes 126 can extend around a portion of the circumference of the tubular member 124 between 170° and 190°. In still other embodiments, the vanes 126 can extend around a portion of the circumference of the tubular member 124 of approximately 180°.

[0064] The reductant inlet port 131 is defined within the tubular member 124 and is configured to allow addition of the reductant into the exhaust gas flow path of the exhaust gas flowing through the mixer 120. In some embodiments, the reductant inlet port 131 may be defined upstream of the plurality of vanes. In some embodiments where the mixer 120 includes an upstream set of vanes and a downstream set of vanes, the reductant inlet port 131 may be defined between the upstream set of vanes and the downstream set of vanes. The reductant inlet port 131 is axially aligned with the central portion of the exhaust gas flow path (e.g., aligned with the transverse axis A T and is configured to allow the reductant to be added at a non-zero angle relative to the central portion in a direction opposite to the circumferential direction. For example, along the transverse axis A of the housing 101 T mounted reductant injector 156 is configured to add the reductant through the reductant inlet port 131 at a non-zero angle relative to the transverse axis A in a direction opposite to the circumferential direction of the exhaust gas vortex T into the exhaust gas. In some embodiments, the tubular member 124 further defines an auxiliary opening 133 near the reductant inlet port 131, and the auxiliary opening 133 is configured to allow an auxiliary exhaust gas flow to flow between the housing 101 and the tubular member 124. The auxiliary gas flow can further promote mixing of the reductant with the exhaust gas and reduce, for example, reductant deposition in the reductant inlet port.

[0065] The reductant spray cone generated by the reductant injector is polydisperse and has a limited width. While the spray cone angle (i.e., the opening angle of the spray cone) is a useful measure of the extent of the spray footprint, another useful measure for evaluating the degree of dispersion of the droplet size distribution is the relative span factor (RSF). The RSF is defined as the ratio of the difference between the maximum and minimum droplet sizes of the reductant to the average droplet size, and is an indicator of the range of reductant droplet sizes relative to the average droplet size in the reductant spray. The larger the RSF, the more dispersed the spray. Changes in the RSF can affect the mixing of the reductant with the exhaust gas.

[0066] To facilitate mixing of the injected reductant added by symmetrically mounted reductant injectors 156 that may have a wide range of RSFs, the mixer central axis A defined by the hub 122 of the mixer 120 M is radially offset relative to the housing central axis A of the housing 101 L such that the flow axis of the exhaust gas at a location upstream of the mixer 120 within the housing 101 is also offset from the mixer central axis A M The plurality of openings 127 defined between the plurality of vanes 126, in addition to causing vortices in the exhaust gas, also due to the mixer central axis A M being offset from the housing central axis A LThe openings 127 direct several major intercepted exhaust gas flows to selectively change the trajectory of the reductant spray droplets and redistribute them. By varying the blade angles and / or orientations of the plurality of blades 126 based on the application, sprays with various RSFs can be optimally redistributed. The symmetrically mounted reductant injectors 156 reduce flow recirculation near the tip of the reductant injector 156, thereby reducing the risk of reductant deposits and allowing for large spray cone angles.

[0067] In this manner, the mixer 120 provides multistage oblique virtual interception of reductant droplets by changing the flow axis of the exhaust, increasing mixing, and reducing reductant deposition. Virtual interception refers to the ability of the mixer 120 to produce an exhaust gas flow that intercepts the reductant spray without the use of a splash plate or solid device. Virtual interception selectively changes the trajectory of the reductant droplets and redistributes the reductant droplets. In particular, the mixer 120 is configured to provide oblique virtual interception because the reductant spray is introduced at a non-zero angle or oblique angle relative to one or more main exhaust gas flows generated by the plurality of blades 126 (e.g., Figure 3 shown).

[0068] In some embodiments, Figure 2 As shown, the central axis A of the mixer M From the housing center axis A of the housing 101 L The horizontal offset distance x is (for example, in the range of 0 mm to 20 mm). The reductant injector 156 is relative to the transverse axis A of the housing 101. T Symmetrically mounted and configured relative to the transverse axis A of the housing 101 T The reductant is added at an angle of about 0 degrees so that the central axis of the spray cone SC generated by the reductant injector 156 is aligned with the lateral axis A. T Alignment.

[0069] Figure 3 1 shows a mixer 220 disposed in the housing 101 according to another embodiment. As described with respect to the mixer 120, the mixer 220 includes a hub 222, a tubular member 224, a plurality of blades 226, a blocking member 225, and a flange 228. However, unlike the mixer 120, the mixer center axis of the mixer 220 is aligned with the housing center axis A of the housing 101. L The reductant injector 156 is aligned with respect to the transverse axis A of the housing 101. T The reducing agent is added at a non-zero angle α (eg, in the range of 5 degrees to 60 degrees).

[0070] Figure 4Shows a mixer 120 installed in a housing 101, as described with respect to Figure 2 Unlike Figure 2 , the reductant injector 156 is configured to introduce the reductant at an angle α in the range of 5 degrees to 60 degrees with respect to the transverse axis A of the housing 101. T

[0071] Figure 5 Shows a mixer 120 installed in a housing 101 such that the mixer central axis A of the mixer 120 M Also vertically offsets from the housing central axis A of the housing 101. For example, the mixer central axis of the mixer 120 may be radially offset by a distance R (e.g., in the range of 0 mm to 15 mm) from the housing central axis A and is at an angle β with the transverse axis A L in the range of 30 degrees to 60 degrees. L T

[0072] As described previously herein, in addition to the main intercepted exhaust gas flow generated by the exhaust gas portion flowing through the opening 127 defined between the adjacent vanes 126, one or more auxiliary exhaust gas flows are obtained due to the exhaust gas portion flowing through the auxiliary opening 133 in the tubular member 124. The momentum from one or more auxiliary flows helps to dynamically assist or counteract the momentum of the main intercepted exhaust gas flow with different spray cone angles and reductant spray cones having different RSFs. For example, Figure 6 Shows a side perspective view of a mixer 120 installed in a housing 101 as shown in Figure 5 . A reductant inlet port 131 is defined in the tubular member 124 to allow the introduction of the reductant into the flow path of the exhaust gas flowing through the mixer 120, and an auxiliary opening 133 is defined near the reductant inlet port 131.

[0073] Figure 7 Shows the flow streamlines of the main and auxiliary streamlines of the exhaust gas flowing through the mixer 120. The momentum of the auxiliary streamline affects the reductant spray cone to varying degrees under different flow conditions and changes the reductant spray trajectory, which realizes the ability to dynamically control the reductant spray trajectory and uniformity. Therefore, one or more auxiliary airflows can be introduced through the auxiliary openings to allow for closer dynamic control of the spatial distribution of the reductant spray droplets under different operating conditions.

[0074] Therefore, the oblique virtual interception of the reductant spray and the mixer central axis A MVarious combinations of the radial offset are feasible to achieve the desired ratio of exhaust gas to reductant spray momentum. In this way, an optimal spatial distribution of the droplets in the exhaust gas can be achieved. All such configurations are contemplated and should be understood to be covered by the various embodiments described in this application.

[0075] In various embodiments, the mixer can be configured to provide multiple auxiliary exhaust gas flows. For example, according to another embodiment, Figure 8 A front perspective view of the mixer 320 is shown. The mixer 320 includes: a tubular member 324; a plurality of vanes 326, which include a set of upstream vanes and a set of downstream vanes extending from the hub 322 to the tubular member 324; a flange 328 that extends radially outward from the edge of the upstream end of the tubular member 324; and a blocking member 325 that is coupled to the hub 322 associated with the downstream vanes 326. The reductant injector is arranged to add the reductant spray cone SC between the upstream vanes and the downstream vanes 326 among the plurality of vanes 326. The blocking member 325 located near the addition position of the spray cone SC defines a plurality of through holes 329 therethrough. Multiple auxiliary exhaust gas flows are generated by the exhaust gas flowing through the through holes 329, further promoting the mixing of the reductant and the exhaust gas and reducing the reductant deposition.

[0076] Figure 9 A front perspective view of the mixer 420 according to another embodiment is shown. The mixer includes a hub 422, a tubular member 424, a plurality of vanes 426 extending from the hub 422 to the tubular member 424, a blocking member 425 also extending from the hub 422 to the tubular member 424, and a flange 428 that extends radially outward from the edge of the upstream end of the tubular member 424. The mixer central axis of the mixer 420 can be radially offset from the longitudinal axis of the housing, where the mixer 420 is disposed in the housing. The reductant inlet port 431 is defined in the tubular member 424 upstream of the plurality of vanes 426, and the spray cone of the reductant is added into the flow path of the exhaust gas flowing through the mixer 420 through the reductant inlet port 431. A slit 429 is defined through the vane 426a among the plurality of vanes 426, and the vane 426a is located at a position away from the reductant inlet port 431. In addition to the auxiliary exhaust gas flow generated by the hub 422, the slit 429 also generates an auxiliary exhaust gas flow to promote mixing and reduce reductant deposition. Although Figure 9 Only one vane 426a is shown defining the slit 429, but in other embodiments, more than one vane among the plurality of vanes 426, such as 2, 3, 4 or all the vanes, can define one or more slits therethrough.

[0077] Although the present disclosure describes various mixers, the systems and methods described herein may include any mixer described in U.S. Patent Application No. 16 / 442,014, filed on June 14, 2019, the entire disclosure of which is incorporated herein by reference.

[0078] Figure 10 FIG. 500 is a schematic flow chart of a method 500 for manufacturing a post-treatment system (such as post-treatment system 100) according to one embodiment. Method 500 includes: at 502, providing a housing (such as housing 101) for the post-treatment system. At 504, disposing an SCR system (such as SCR system 150) in the housing. At 506, disposing a mixer (such as mixers 120, 220, 320, 420) upstream of the SCR system 150 in the housing 101. The mixer includes a hub (such as hubs 122, 222, 322, 422) and a tubular member (such as tubular members 124, 224, 324, 424) circumferentially surrounding the hub and defining a reductant inlet port. A plurality of vanes (such as vanes 126, 226, 326, 426) extend from the hub to the tubular member such that openings are defined between adjacent vanes of the plurality of vanes to allow exhaust gas to flow therethrough. The plurality of vanes are configured to vortex the exhaust gas circumferentially with respect to the exhaust gas flow path. The mixer is disposed such that a mixer central axis defined by the hub of the mixer is radially offset with respect to a housing central axis of the housing, such that a flow axis of the exhaust gas at a position upstream of the mixer in the housing is also offset from the mixer central axis. At 508, a reductant injector (such as reductant injector 156) is disposed on the housing along a transverse axis of the housing upstream of the SCR system. The reductant injector is configured to add reductant through the reductant inlet port into the exhaust gas flowing through the housing at a non-zero angle with respect to the transverse axis opposite to the circumferential direction of rotation of the exhaust gas.

[0079] It should be noted that, as used herein, the term "example" used to describe various embodiments is intended to indicate that such embodiments are possible examples, representatives, and / or illustrations of possible embodiments (and such terms are not intended to mean that such embodiments must be particular or excellent examples).

[0080] As used herein, the terms "about" and "approximately" generally refer to plus or minus 10% of the stated value. For example, about 0.5 will include from 0.45 to 0.55, about 10 will include from 9 to 11, and about 1000 will include from 900 to 1100.

[0081] As used herein, terms such as "coupled" mean that two components are directly or indirectly connected to each other. Such a connection can be fixed (e.g., permanent) or movable (e.g., detachable or releasable). Such a connection can be achieved by integrally forming two components or two components and any additional intermediate components into a single unit with each other, or by attaching two components or two components and any additional intermediate components to each other.

[0082] It is important to note that the structures and arrangements of the various exemplary embodiments are merely illustrative. Although only a few embodiments are described in detail in this disclosure, those skilled in the art who review this disclosure will readily recognize that many modifications are possible (e.g., changes in the sizes, dimensions, structures, shapes and proportions of the various elements, the values of the parameters, the mounting arrangements, the use of materials, the colors, the orientations, etc.), without materially departing from the novel teachings and advantages of the subject matter described herein. In addition, it should be understood that features from one embodiment disclosed herein can be combined with features from other embodiments disclosed herein, as would be understood by a person of ordinary skill in the art. Other alternatives, modifications, variations and omissions can also be made in the design, operating conditions and arrangements of the various exemplary embodiments without departing from the scope of this embodiment.

[0083] Although this specification contains many specific implementation details, these should not be construed as limitations on the scope of any embodiment or on what can be claimed, but rather as descriptions of features that are specific to particular implementations of particular embodiments. Certain features described in the context of separate implementations in this specification can also be implemented in combination in a single implementation. Conversely, the various features described in the context of a single implementation can also be implemented separately in multiple implementations or in any suitable sub-combination. In addition, although the above features may be described as acting in certain combinations and even initially claimed as such, in some cases, one or more features from a claimed combination can be deleted from that combination, and the claimed combination can relate to a sub-combination or a variation of a sub-combination.

Claims

1. A post-treatment system for treating the components of the exhaust gas generated by an engine, comprising: a housing defining a housing central axis; a selective catalytic reduction (SCR) system disposed in the housing; a mixer disposed in the housing upstream of the SCR system, the mixer comprising: a hub; a tubular member circumferentially surrounding the hub and defining a reductant inlet port extending radially through the tubular member; and a plurality of vanes extending from the hub to the tubular member such that openings are defined between adjacent vanes of the plurality of vanes to allow the exhaust gas to flow through the openings, such that the plurality of vanes cause the exhaust gas to vortex in a circumferential direction with respect to the exhaust gas flow path of the exhaust gas; and a reductant injector disposed on the housing upstream of the SCR system and configured to add a reductant into the exhaust gas flowing through the housing through the reductant inlet port, wherein the reductant injector is configured to add the reductant such that: (i) in a plane parallel to the housing central axis, the reductant addition direction is perpendicular to the housing central axis and is located at a position upstream of the SCR system, and (ii) in a plane perpendicular to the housing central axis, the reductant addition direction forms a non-zero angle with respect to a transverse axis of the housing extending through the reductant injector, the mixer, and the housing central axis, wherein a mixer central axis defined by the hub of the mixer is radially offset from the housing central axis at a position upstream of the SCR system in the housing.

2. The post-treatment system according to claim 1, wherein, the mixer central axis is horizontally offset from the housing central axis.

3. The post-treatment system according to claim 2, wherein, the mixer central axis is vertically offset from the housing central axis.

4. The post-treatment system according to claim 1, wherein, the non-zero angle is in the range of 5 degrees to 60 degrees with respect to the transverse axis.

5. The post-treatment system according to claim 1, wherein, an auxiliary opening is defined in the tubular member near the reductant inlet port.

6. The post-treatment system according to claim 1, wherein, the housing defines a cross-section that is circular, square, rectangular, oval, elliptical, or polygonal.

7. The post-treatment system according to any one of claims 1-6, wherein, the mixer further comprises a flange radially extending outward from an edge of an upstream end of the tubular member and fixed to an inner surface of the housing.

8. The post-treatment system according to any one of claims 1-6, further comprising: a blocking member extending from the hub to the tubular member.

9. The post-treatment system according to claim 8, wherein, the plurality of vanes extend from the hub to the tubular member around a portion of the circumference of the tubular member between 130 degrees and 230 degrees.

10. The post-treatment system according to claim 8, wherein, a plurality of through-holes are defined through the blocking member.

11. The post-treatment system according to any one of claims 1-6 and 9-10, wherein, a slit is defined through at least one of the plurality of vanes.

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