Bladed mixer in an engine exhaust system

Abstract

An exhaust system for an internal combustion engine includes an exhaust pipe and a vane mixer attached to an upstream pipe end of the exhaust pipe and including a fluid injector mount and a fluid injection side port in the injector mount and fluidly connected to an exhaust passage in the vane mixer. The vane mixer further includes vanes extending across the exhaust passage and dividing the exhaust passage into a primary flow area and a secondary flow area. The secondary flow area is aligned at an overlap angle circumferentially around a longitudinal exhaust passage axis from the fluid injection side port.

Description

Technical Field

[0001] This disclosure generally relates to an exhaust system for an internal combustion engine, and more specifically to a blade mixer in an exhaust system having blades positioned to be impacted by a combined flow of exhaust and injected fluid. Background Technology

[0002] Most modern internal combustion engines include some type of equipment to reduce the emission of certain compounds into the environment. In recent years, and especially with compression-ignition diesel engines, judicial requirements regarding permissible limits for particulate matter and nitrogen oxides, or "NOx," have become increasingly stringent. Internal combustion engines typically have an exhaust system equipped with various catalytic converters, traps, and other devices for filtering such compounds or converting them into materials that are not undesirable.

[0003] In conventional strategies, diesel particulate filters (DPFs) are used to capture particulate matter, including soot and ash. For example, selective catalytic reduction modules (SCRs) are typically coupled downstream of the DPF to convert NOx into molecular nitrogen and water. Over time, the performance of the catalyst degrades, and the filter or trap may accumulate captured particles. Therefore, regular maintenance of such equipment, or more preferably, regeneration of the on-board equipment, is desirable. In the case of DPFs, various engine operating strategies can be implemented to increase the exhaust temperature sufficiently to burn the captured particles. Strategies that rely on controlling the combustion process itself may adversely affect performance and / or result in unacceptable fuel losses. Other strategies employ electric heaters in the DPF, expensive precious metal catalysts to achieve more or less continuous passive regeneration, or direct injection of fuel (such as on-board diesel fraction fuel) into the exhaust stream to initiate the combustion of captured particles. All of these strategies have various advantages in certain applications, but also various disadvantages. In the case of active regeneration with direct fuel injection into the exhaust, known systems may not have sufficient capacity to mix the injected fuel with the exhaust, ultimately leading to undesirable emissions of unburned hydrocarbons or interactions between hydrocarbons and downstream equipment intended for combustion. A known active regeneration strategy is proposed in U.S. Patent No. 9,010,094 to O'Neil et al. Summary of the Invention

[0004] On one hand, an exhaust system for an engine includes an exhaust pipe having an upstream end and a downstream end. The exhaust system further includes a vane mixer defining a longitudinal passage axis and forming an exhaust passage extending between a downstream mixer end attached to the upstream end and the upstream mixer end. The vane mixer includes an injector mount and a fluid injection side port formed in the injector mount and fluidly connected to the exhaust passage. The vane mixer further includes blades extending across the exhaust passage and dividing the exhaust passage into a primary flow region and a secondary flow region. The secondary flow region is circumferentially aligned with the fluid injection side port at an overlap angle around the longitudinal passage axis.

[0005] On the other hand, a blade mixer for an exhaust system in an internal combustion engine includes: a mixer body having an exhaust duct defining a longitudinal passage axis and having an outer duct surface and an inner duct surface extending circumferentially around the longitudinal passage axis to form an exhaust passage extending between an upstream mixer end and a downstream mixer end. The mixer body further includes: an injector mount; and a fluid injection side port formed in the injector mount and defining a transverse port axis forming an acute angle with the longitudinal passage axis. The blade mixer further includes: blades extending across the exhaust passage and having a trailing edge positioned downstream of the fluid injection side port and a leading edge positioned to be impacted by a combined flow of exhaust gas through the exhaust passage and injected fluid through the fluid injection side port. The blades divide the exhaust passage into a primary flow region and a secondary flow region, and the secondary flow region is aligned circumferentially around the longitudinal passage axis at an overlap angle with the fluid injection side port.

[0006] In another aspect, a blade mixer for an exhaust system in an internal combustion engine includes: a mixer body having an exhaust duct defining a longitudinal passage axis and having an outer duct surface and an inner duct surface extending circumferentially around the longitudinal axis to form an exhaust passage extending between an upstream mixer end and a downstream mixer end. The mixer body further includes a fluid injection side port fluidly connected to the exhaust passage at a location longitudinally located between the upstream and downstream mixer ends, and defining a transverse port axis intersecting the longitudinal passage axis and forming an acute angle with the longitudinal axis. The blade mixer further includes: a blade extending across the exhaust passage and having a trailing edge located downstream of the fluid injection side port and a leading edge; and a gap extending longitudinally between the transverse port axis and the leading edge of the blade. Attached Figure Description

[0007] Figure 1 This is a schematic view of an internal combustion engine system according to one embodiment;

[0008] Figure 2 yes Figure 1 A partial cross-sectional view of the internal combustion engine section;

[0009] Figure 3 This is a cross-sectional side view of a guide vane mixer according to one embodiment;

[0010] Figure 4 yes Figure 3 Another schematic diagram of a blade mixer;

[0011] Figure 5 yes Figure 3 End view of the blade mixer;

[0012] Figure 6 yes Figure 3 Another schematic diagram of a blade mixer; and

[0013] Figure 7 It is a graph showing the concentration of unburned hydrocarbons in the exhaust system according to this disclosure compared to another exhaust system. Detailed Implementation

[0014] refer to Figure 1 and 2 The diagram illustrates an internal combustion engine system 10 according to one embodiment. The internal combustion engine system 10 (hereinafter referred to as "engine system 10") includes an engine 12 having a cylinder block 14. The cylinder block 14 may include any number of cylinders in any suitable arrangement. The engine 12 may be a compression ignition engine, including a piston within the cylinder block 14 configured to compress a mixture of fuel (such as a liquid diesel fraction fuel) and air within the cylinder to an auto-ignition threshold. However, this disclosure is not limited thereto, and the engine 12 may be a liquid-ignition spark-ignition dual-fuel engine operating on both liquid and gaseous fuels, or another type. In a generally conventional manner, the engine system 10 further includes an exhaust system 16, which includes a turbocharger 18 having a compressor 20 and a turbine 22 coupled to the compressor 20 and including a turbine outlet 24.

[0015] The exhaust system 16 also includes aftertreatment equipment 26, including, for example, a diesel oxidation catalyst 28 or "DOC", a particulate filter 30 or "DPF", and a selective catalytic reduction module 32 or "SCR". The exhaust system 16 also includes an exhaust vertical or tailpipe 34 configured to discharge exhaust gas treated in the aftertreatment equipment 26. Some or all of the aftertreatment equipment 26 may be located inside the engine cover 38. The engine system 10 can be used in off-highway machinery such as tractors, trucks, excavators, etc. The engine system 10 can also be implemented in stationary engine-generator sets, pumps, compressors, or other machines. The exhaust system 16 also includes an exhaust pipe 40 having an upstream end 42 and a downstream end 44. The exhaust pipe 40 forms a first bend 46 and a second bend 48 between the upstream end 42 and the downstream end 44, and includes a bellows 50 between the first bend 46 and the second bend 48. The bellows 50 allows for some flexure and movement between and within the various components of the engine system 10, as may be experienced in mobile machinery applications, particularly off-highway machinery applications. As will become further apparent from the following description, the exhaust system 16 is configured to improve the performance of fluid injection (e.g., liquid fuel) into the exhaust flow from the engine 12 and the mixing of the injected fluid with the exhaust, as well as to improve the encapsulation of the exhaust system components.

[0016] Still referencing Figure 3-6 The exhaust system 16 further includes a blade mixer 52 defining a longitudinal passage axis 62 and forming an exhaust passage 68 extending between a downstream mixer end 72 and an upstream mixer end 70. The downstream mixer end 72 is attached to an upstream pipe end 42, and the upstream mixer end 70 is attachable to a turbine 22 to receive exhaust feed from a turbine outlet 24. The blade mixer 52 also includes a mixer body 58 having an exhaust duct 60 defining the longitudinal passage axis 62 and having an outer duct surface 64 and an inner duct surface 66 extending circumferentially around the longitudinal passage axis 62 to form the exhaust passage 68. The exhaust passage 68 extends between the upstream mixer end 70 and the downstream mixer end 72. As used herein, the term “upstream” means in the direction of the engine 12 or in the direction of the upstream mixer end 70, and “downstream” means in the direction of the tailpipe 34 or the downstream mixer end 72.

[0017] The mixer body 58 further includes an injector mount 74 and a fluid injection side port 76 formed in the injector mount 74 and defining a transverse port axis 78 forming an acute angle 84 with the longitudinal axis 62. In some embodiments, the acute angle 84 opens in an upstream direction and may be between 45° and 60°, for example, about 50°. The exhaust system 16 further includes a liquid injector 54, such as a fuel injector, mounted to the injector mount 74 and configured to inject liquid fuel into the vane mixer 52. A fuel line 56 extends to the fuel injector 54 and may supply liquid fuel (such as diesel fraction fuel from an onboard fuel tank) to the fuel injector 54 for injection. The injection of liquid fuel using the fuel injector 54 can be used for regenerating the aftertreatment device 26, specifically the DPF 30. Fuel injection may be periodic, continuous, or triggered in response to the detection of suitable DPF regeneration conditions. As mentioned above, the vane mixer 52 may be configured to improve the mixing of injected fuel with exhaust gas. The improved hybridization can then enable the use of relatively short exhaust pipes 40, relatively tortuous exhaust pipe paths 40, or provide other benefits related to efficient and compact encapsulation and the performance of the exhaust system 16. In a practical implementation strategy, the fuel injector 54 defines an injector axis 57 that is parallel to and generally collinear with the lateral port axis 78. The spray plume of injected fuel from the fuel injector 54 may have a spray plume path that is generally parallel to and circumferentially circumferential to the injector axis 57.

[0018] As described above, the mixer body 58 may include an injector mount 74. (As in...) Figure 6 As can be seen, for example, the injector mount 74 may protrude from the outer conduit surface 64 and includes a mounting surface 80 having a fluid injection side port 76 and a plurality of fastener holes 82 formed therein. The blade mixer 52 further includes blades 86 extending across the exhaust passage 68, which facilitate mixing the injected fuel with the exhaust gas and have a trailing edge 88 positioned downstream of the fluid injection side port 76, and a leading edge 90 impinged by the combined flow of exhaust gas through the exhaust passage 68 and injected fluid (i.e., fuel) through the fluid injection side port 76. The blades 86 may further divide the exhaust passage 68 into a primary flow region 92 and a secondary flow region 94. The primary flow region herein refers to a flow region with a relatively large cross-sectional area, and the secondary flow region refers to a flow region with a relatively small cross-sectional area. The secondary flow region 94 is circumferentially aligned with the fluid injection side port 76 at an overlap angle around the longitudinal passage axis 62. In the axial projection plane, as can be seen from... Figure 5Constructed, the exhaust duct 60 defines a circle 96 centered on a longitudinal passage axis 62. The blade 86 defines a chord 98 of the circle 96. The transverse port axis 78 can be understood as bisecting the secondary flow region 94 in the axial projection plane and also bisecting the chord 98. The blade 86 can be further understood as including an inner blade surface 87, which, together with the inner duct surface 60, forms the secondary flow region 94 of the exhaust passage 68. The blade 86 can also be understood as including an outer blade surface 89, which, together with the inner duct surface 60, forms the primary flow region 92 of the exhaust passage 68.

[0019] For example Figure 3 As shown, gap 110 extends longitudinally between the transverse port axis 78 and the leading edge 90 of blade 86. In at least some embodiments, the transverse port axis 78 intersects the longitudinal passage axis 62 downstream of the leading edge 90 of blade. Blade 86 may be oriented generally horizontally relative to the incoming exhaust flow, such that the inner blade surface 87 and the outer blade surface 89 extend generally parallel to the longitudinal passage axis 62. It should also be understood that, given the further description herein, the position, location, orientation, and configuration of blade 86 facilitate the mixing of the injected fuel and exhaust flow. In lower load operations where exhaust mass flow and velocity may be relatively small, the fuel injection spray plume may not directly impact the leading edge 90 of blade 86 based on gap 110. In other words, the central axis of the fuel spray plume will not impact the leading edge 90. Under higher loads with larger exhaust mass flow and larger exhaust velocity, the exhaust flow in the upstream-to-downstream direction may be sufficient to deflect the incoming fuel spray plume to directly impact the leading edge 90. As a result, at least under higher load conditions, some of the injected fuel will flow through the secondary flow region 94 and some of the injected fuel will flow through the primary flow region 92, where this flow separation in a general manner helps to mix with the exhaust flow.

[0020] The fluid injection side port 76 can transition through the opening in the conduit 60 formed by the transition surface 120 along with the exhaust passage 68. The transition surface 120 can have dimensions and curvature such as... Figure 3 The longitudinal cross-sections shown are inconsistent. The first radius 122 formed by the transition surface 120 on the upstream side of the fluid injection side port 76 can be relatively small, and the second radius 124 formed by the transition surface 120 on the downstream side of the fluid injection side port 76 can be relatively large. In practical embodiments, the sizes of radii 122 and 124 can be between 10 mm and 20 mm. The larger size of radius 124 can help to shape the profile of the downstream side of the fluid injection side port 76 in order to limit or avoid the impact of injected fuel spray on the inner conduit surface 66 and / or the inner surface of the fluid injection side port 76.

[0021] You can also from Figure 3 As noted in the other figures, the inner conduit surface 66 can be understood as forming an inlet exhaust passage segment 112, an outlet exhaust passage segment 114, and an intermediate exhaust passage segment 116. The diameter of the outlet exhaust passage segment 114 may be larger than that of the inlet exhaust passage segment 112. The intermediate exhaust passage segment 116 may have a diameter that increases longitudinally from the inlet exhaust passage segment 112 to the outlet exhaust passage segment 114. The fluid injection side port 76 may open to the intermediate exhaust passage segment 116, such that the enlarged diameter of the intermediate exhaust passage segment 116 and the larger diameter of the outlet exhaust passage segment 114 help to provide additional volume for mixing the injected fuel with the exhaust gas. It can also be seen in the figures that the upstream mixer end 70 includes a first axial end surface 100. The first axial end surface 100 may be formed on the connecting flange 104 of the upstream mixer end 70. The downstream mixer end 72 includes a second axial end surface 102 and a second flange 106 adjacent to and spaced upstream of the second axial end surface 102. The trailing edge 88 of the blade may be coplanar with the second axial end surface 102.

[0022] Industrial applicability

[0023] Refer to the attached diagram for general details, but now refer to... Figure 7 A graph 200 shows the unburned hydrocarbon concentration of an exhaust system according to the present disclosure at line 220, compared to the unburned hydrocarbon concentration of an exhaust system without a blade mixer. In graph 200, the X-axis shows the hydrocarbon concentration expressed in parts per million (ppm), and the Y-axis shows the percentage of flow passages in exhaust system components (such as DOC) where the corresponding unburned hydrocarbon concentration was detected. It can be seen that, in the case of an exhaust system operating with a blade mixer according to the present disclosure, the unburned hydrocarbon concentration is significantly lower than in a system without a blade mixer, specifically at a concentration from about 400 ppm to about 650 ppm.

[0024] In some early exhaust systems, it has been observed that, with the use of relatively short exhaust pipes or "flexible pipes," the injected liquid fuel may not evaporate and mix optimally, resulting in relatively poor fuel mix quality, specifically due to higher flow rates in the channels of the DOC (given the reduced residence time available for such mixing) and higher temperatures. Maintaining a leak-free pipe can also be challenging with relatively short lengths. However, relatively long exhaust pipes require an expanded encapsulation width, which may be unacceptable for various reasons, including cost. Conventional mixers that obstruct most of the exhaust pipe can address these challenges but often introduce potentially undesirable pressure drop losses. Conventional mixing strategies and mixing hardware can also be less reliable over performance life or service intervals. This disclosure provides an improved mixing solution without such drawbacks, enabling the dispersion of fuel spray from fuel injectors supporting shorter exhaust pipes, better vaporization to limit leakage, and other potential advantages, particularly regarding a compact encapsulation.

[0025] This specification is for illustrative purposes only and should not be construed as limiting the scope of this disclosure in any way. Therefore, those skilled in the art will recognize that various modifications may be made to the embodiments currently disclosed without departing from the full and reasonable scope and spirit of this disclosure. Other aspects, features, and advantages will become apparent from the accompanying drawings and claims. As used herein, the articles “a” and “an” are intended to include one or more items and are interchangeable with “one or more”. The term “one” or similar language is used when intended to indicate only one item. Furthermore, as used herein, the terms “has,” “have,” “having,” etc., are intended to be open-ended terms. Additionally, the phrase “based on” is intended to mean “at least partially based on”, unless otherwise expressly stated.

Claims

1. An exhaust system for an engine, the exhaust system comprising: An exhaust pipe, the exhaust pipe including an upstream pipe end and a downstream pipe end; A blade mixer defining a longitudinal passage axis and forming an exhaust passage extending between a downstream mixer end attached to the upstream pipe end and an upstream mixer end, the blade mixer including an injector mount and a fluid injection side port formed in the injector mount and fluidly connected to the exhaust passage, the fluid injection side port defining a lateral port axis; and The blade mixer further includes blades that extend across the exhaust passage and divide the exhaust passage into a primary flow region and a secondary flow region, wherein the secondary flow region is aligned circumferentially around the longitudinal passage axis with the fluid injection side port at an overlap angle. The blade includes a trailing edge located downstream of the fluid injection side port and a leading edge, and the gap extends in the longitudinal direction between the transverse port axis and the leading edge of the blade, wherein the transverse port axis intersects the longitudinal passage axis at a position downstream of the leading edge of the blade.

2. The exhaust system according to claim 1, wherein: The exhaust pipe forms a first bend and a second bend between the upstream pipe end and the downstream pipe end, and includes a bellows between the first bend and the second bend. The transverse port axis forms an acute angle with the longitudinal passage axis, opening in the upstream direction; and The secondary flow region is bisected by the transverse port axis in the axial projection plane.

3. The exhaust system according to claim 2, further comprising: The exhaust turbine is fluidly connected to the upstream end of the pipe, the diesel oxidation catalyst (DOC) is fluidly connected to the downstream end of the pipe, and the particulate filter (DPF) is fluidly connected to the DOC. as well as A fuel injector, which is mounted to the injector mount and configured to inject liquid fuel into the blade mixer, wherein the fuel injector defines an injector axis parallel to the transverse port axis and the acute angle is between 45° and 60°.

4. A vane mixer for an exhaust system in an internal combustion engine, comprising: A mixer body having an exhaust duct defining a longitudinal passage axis and having an outer duct surface and an inner duct surface extending circumferentially around the longitudinal passage axis to form an exhaust passage extending between an upstream mixer end and a downstream mixer end. The mixer body further includes: an injector mount; and a fluid injection side port formed in the injector mount and defining a transverse port axis forming an acute angle with the longitudinal passage axis; and The blade extends across the exhaust passage and includes a trailing edge positioned downstream of the fluid injection side port and a leading edge positioned to be impacted by a combined flow of exhaust fluid through the exhaust passage and injected fluid through the fluid injection side port. A gap extends in the longitudinal direction between the transverse port axis and the leading edge of the blade, the transverse port axis intersecting the longitudinal passage axis at a position downstream of the leading edge of the blade. The blades divide the exhaust passage into a primary flow region and a secondary flow region, and the secondary flow region is aligned with the fluid injection side port at an overlap angle around the longitudinal passage axis in the circumferential direction.

5. The blade mixer according to claim 4, wherein: The exhaust duct defines a circle centered on the longitudinal passage axis, and the blade defines the chord of the circle, and the transverse port axis bisects the secondary flow region and the chord of the circle in the axial projection plane.

6. The blade mixer according to claim 4 or claim 5, wherein: The surface of the inner duct forms an inlet exhaust passage segment, an outlet exhaust passage segment, and an intermediate exhaust passage segment, and the diameter of the outlet exhaust passage segment is larger than the diameter of the inlet exhaust passage segment; The secondary flow region is more than 10 times smaller than the primary flow region; and The upstream mixer end includes a connecting flange that forms a first axial end surface of the mixer body, and the downstream mixer end includes a second axial end surface of the mixer body, and a second flange adjacent to and spaced upstream of the second axial end surface, and the trailing edge of the blade is coplanar with the second axial end surface.

7. The blade mixer of claim 6, wherein the intermediate exhaust passage segment has a diameter that increases in the longitudinal direction from the inlet exhaust passage segment to the outlet exhaust passage segment, and the fluid injection side port leads to the intermediate exhaust passage segment.

8. The blade mixer according to claim 5, wherein the blade and the mixer body are integrally formed as a single piece.

9. A vane mixer for an exhaust system in an internal combustion engine, comprising: A mixer body having an exhaust duct defining a longitudinal passage axis and having an outer duct surface and an inner duct surface extending circumferentially around the longitudinal passage axis to form an exhaust passage extending between an upstream mixer end and a downstream mixer end. The mixer body further includes a fluid injection side port, which is fluidly connected to an exhaust passage at a position located longitudinally between the upstream mixer end and the downstream mixer end, and defines a transverse port axis that intersects the longitudinal passage axis and forms an acute angle with the longitudinal passage axis; as well as The blade extends across the exhaust passage and includes a trailing edge of the blade located downstream of the fluid injection side port and a leading edge of the blade, and a gap extends in the longitudinal direction between the transverse port axis and the leading edge of the blade, the transverse port axis intersecting the longitudinal passage axis at a location downstream of the leading edge of the blade.

10. The blade mixer according to claim 9, wherein: The blade includes an inner blade surface that forms a secondary flow region of the exhaust passage together with the inner duct surface, and an outer blade surface that forms a primary flow region of the exhaust passage together with the inner duct surface. The secondary flow region is aligned with the fluid injection side port at an overlapping angle around the longitudinal passage axis in the circumferential direction. The surface of the inner duct forms an inlet exhaust passage segment, an outlet exhaust passage segment, and an intermediate exhaust passage segment, and... The intermediate exhaust passage segment has a diameter that increases in the longitudinal direction from the inlet exhaust passage segment to the outlet exhaust passage segment, and the fluid injection side port leads to the intermediate exhaust passage segment.

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