Exhaust aftertreatment arrangement for cleaning exhaust gases

Abstract

To provide an exhaust aftertreatment arrangement for cleaning exhaust gases.SOLUTION: The exhaust aftertreatment arrangement comprises: a fluid channel (21) for providing a fluid pathway for the exhaust gases; an SCR catalyst arranged in or downstream of the fluid channel; and a heating arrangement (38) for heating the exhaust gases, the heating arrangement being arranged upstream of the SCR catalyst. The heating arrangement comprises: an electrical heating element; a first fluid pathway for guiding the exhaust gases to the electrical heating element; and a second fluid pathway for guiding the exhaust gases to bypass the electrical heating element, the heating arrangement being removably arranged relative to the fluid channel. The invention also relates to a heating arrangement and a vehicle.SELECTED DRAWING: Figure 3A

Description

Technical Field

[0001] The present invention relates to an exhaust aftertreatment device for purifying exhaust. The present invention further relates to a heating device for an exhaust aftertreatment device, a vehicle equipped with the exhaust aftertreatment device or the heating device, and a method for assembling and / or removing the heating device with respect to a fluid conduit of the exhaust aftertreatment device.

Background Art

[0002] Vehicles generally include an engine that propels the vehicle. This engine can operate by various means such as, for example, liquid fuel or gaseous fuel of an internal combustion engine, or electric power of an electromechanical device. There are also hybrid solutions where the vehicle is propelled by both an internal combustion engine and an electromechanical device.

[0003] When the engine is an internal combustion engine such as a diesel engine, it is common for the vehicle to be equipped with an exhaust aftertreatment system EATS that processes emissions from the engine. The EATS of a diesel engine generally includes a diesel oxidation catalyst DOC, a diesel particulate filter DPF, and an SCR (Selective Catalytic Reduction) catalyst. A reducing agent containing substances such as urea or ammonia is injected upstream of the SCR catalyst and uses the catalyst to promote the conversion of nitrogen oxides, also called NOx, into diatomic nitrogen N2, water, and in some cases carbon dioxide CO2 (depending on the choice of reducing agent). The purified exhaust, or at least the exhaust with reduced emissions, is then discharged from the EATS and the vehicle through the vehicle's tailpipe. Other types of engines as diesel engines that produce similar emissions can utilize the same or similar EATS.

[0004] Government regulations, along with the relentless demand for improved vehicle fuel efficiency, necessitate more effective operation of EATS (Exhaust Emissions Processing System). For example, EATS must heat up rapidly, even at low exhaust temperatures, and must have high conversion efficiency even at very low loads. The need for highly efficient engines that meet stringent CO2 requirements also leads to lower exhaust temperatures and increased NOx emissions from the engine, requiring large amounts of reducing agent injected upstream of the SCR catalyst. Furthermore, if urea is used as the reducing agent, it needs to be heated and evaporated to hydrolyze into ammonia. At low temperatures, there is a significant risk of forming crystals and deposits that reduce the effectiveness of EATS.

[0005] Heating the exhaust gases using electric heating elements can offset the low-temperature exhaust gases and mitigate associated problems. However, adding electric heating elements to an EATS increases system complexity and / or adds components that are prone to failure and require maintenance or replacement. Furthermore, heating the exhaust gases with electric heating elements generally induces undesirable pressure drops in the EATS. [Overview of the project] [Problems that the invention aims to solve]

[0006] Therefore, an improved EATS aimed at mitigating the aforementioned shortcomings is needed in industry. [Means for solving the problem]

[0007] The object of the present invention is to provide an improved exhaust aftertreatment system that at least partially mitigates the aforementioned drawbacks of known exhaust aftertreatment systems.

[0008] According to a first aspect of the present invention, an exhaust gas aftertreatment device for purifying exhaust gas is provided. The exhaust gas aftertreatment device comprises a fluid conduit providing a fluid passage for the exhaust gas, an SCR catalyst disposed in or downstream of the fluid conduit, and a heating device disposed upstream of the SCR catalyst for heating the exhaust gas. The heating device comprises an electric heating element, a first fluid passage for guiding the exhaust gas to the electric heating element, and a second fluid passage for guiding the exhaust gas to bypass the electric heating element, and is detachably disposed relative to the fluid conduit.

[0009] Therefore, the disadvantage of low exhaust temperature is mitigated by the electric heating element, while the heating device can be easily removed from the fluid conduit to access the components and fluid passages within the fluid conduit. The pressure drop in the fluid conduit can be limited by utilizing a second fluid passage that guides the exhaust to bypass the electric heating element. As a result, at least the electric heating element and the first and second fluid passages become accessible, for example, for maintenance. That is, the heating device is configured to be removable from the fluid conduit, and the components and fluid passages within the fluid passage become accessible, for example, for maintenance. Furthermore, if the electric heating element is replaced or if it is subject to maintenance from outside the exhaust aftertreatment system, the electric heating element can be easily accessed for removal from the heating device. The present invention provides a simple configuration combination that allows easy access to the components and fluid passages of the heating device while improving the performance of the exhaust aftertreatment system. Therefore, an improved exhaust aftertreatment device is provided, in which the heating device is detachably positioned relative to the fluid conduit, thereby suppressing further complexity of the heating device, while efficiently removing exhaust emissions for heating the exhaust by at least an electric heating element, and reducing pressure drop for a second fluid passage that bypasses at least the electric heating element. For the second fluid passage, at least a portion of the exhaust can be guided from upstream to downstream of the heating device without passing through the electric heating element.

[0010] It should be understood that the pressure drops induced in the first and second fluid passages differ for the same exhaust flow due to the exhaust flow passing through the heating device. Specifically, for the same exhaust flow, the first fluid passage induces a greater pressure drop than the second fluid passage because it has an electric heating element, at least in the first fluid passage. Consequently, the second fluid passage generally lacks an electric heating element or corresponding means to obstruct the flow in the same way as the electric heating element in the first fluid passage.

[0011] Since the heating device is detachably positioned relative to the fluid conduit, it can be positioned in an assembled state where it is positioned in the fluid conduit, or in an assembled state where it forms an integrated part of the fluid conduit and is in direct fluid communication with the fluid conduit, or it can be positioned in a detached state where it is removed or disconnected from the fluid conduit. When using the exhaust aftertreatment system, i.e., when using the exhaust aftertreatment system that converts NOx emissions, the heating device is positioned in an assembled state. The detached state can be used, for example, during maintenance of the heating device, or any component or fluid passage within the heating device.

[0012] According to at least one exemplary embodiment, the heating device comprises a first conduit section including a first fluid passage and an electric heating element, and a second conduit section including a second fluid passage, wherein the second conduit section is different from the first conduit section.

[0013] As a result, each of the first and second fluid passages is contained within a different conduit section. Therefore, the exhaust gas can be effectively separated into the first and second fluid passages, and mixing of the exhaust gases in the first and second fluid passages can be avoided. Furthermore, by providing the heating device with first and second conduit sections, these sections can be easily accessed when removing the heating device from the fluid conduit. Therefore, the first and second conduit sections can be easily accessed for maintenance.

[0014] According to at least one exemplary embodiment, the first and second conduit sections may each have conduit walls that surround the first and second fluid paths around their entire circumference. According to at least one exemplary embodiment, the conduit walls of the first and / or second conduit section define a cross-section that is at least partially curved. That is, the cross-sections of the first and / or second conduit sections are at least partially curved. According to at least one exemplary embodiment, the electric heating element covers the entire cross-section of the first conduit section, thereby preventing exhaust passing through the first fluid passage from bypassing the electric heating element. In other words, the electric heating element can be mounted around the entire circumference and sealed to the conduit wall of the first conduit section.

[0015] According to at least one exemplary embodiment, the first conduit section and the second conduit section are arranged concentrically.

[0016] As a result, a compact configuration of the first and second conduit sections is provided. Therefore, by concentrically arranging the first and second conduit sections within the heating device, the heating device can be made compact. Thus, a suitable configuration is provided having a heating device that is detachably arranged relative to the fluid conduit.

[0017] According to at least one exemplary embodiment, the first conduit surrounds the second conduit in an annular manner, or the second conduit surrounds the first conduit in an annular manner.

[0018] As a result, a compact configuration of the first and second conduit sections is provided. Therefore, the heating device can be made compact by surrounding the first and second conduit sections within the heating device. Thus, a suitable configuration is provided having a heating device that is detachably arranged relative to the fluid conduit.

[0019] According to at least one exemplary embodiment, the first and second conduit sections are adjacent to each other. In other words, the conduit wall of the first or second conduit section separates the first fluid passage from the second fluid passage.

[0020] In an embodiment in which the first conduit surrounds the second conduit in an annular manner, the conduit wall that at least partially defines the second conduit has an inner wall surface facing the second conduit and an outer wall surface facing the first conduit. Similarly, in an embodiment in which the second conduit surrounds the first conduit in an annular manner, the conduit wall that at least partially defines the first conduit has an inner wall surface facing the first conduit and an outer wall surface facing the second conduit.

[0021] According to at least one exemplary embodiment, the second conduit portion has a circular or tubular cross-section, and the first conduit portion has an annular cross-section (i.e., it has a ring shape). Thus, the circular cross-section of the second conduit portion can surround the annular cross-section of the first conduit portion. According to at least one other exemplary embodiment, the first conduit portion has a circular or tubular cross-section, and the second conduit portion has an annular cross-section (i.e., it has a ring shape). Thus, the circular cross-section of the first conduit portion can surround the annular cross-section of the second conduit portion.

[0022] According to at least one exemplary embodiment, the exhaust aftertreatment device further comprises at least one valve configured to control the exhaust flow in first and second fluid passages.

[0023] As a result, the exhaust flow can be controlled and separated into a first fluid passage and a second fluid passage in a simple manner. Generally, heating devices are arranged so that, in their assembled state, a valve controls the exhaust flow to the first fluid passage and / or the second fluid passage. In other words, the valve is configured to control the exhaust flow by directing or guiding the exhaust to a first fluid passage through which the exhaust passes the electric heating element, and to a second fluid passage through which the exhaust bypasses the electric heating element.

[0024] According to at least one exemplary embodiment, the heating device includes a valve.

[0025] As a result, the valve is disposed close to or adjacent to the first and second fluid passages, and thus can effectively control the exhaust flow to the first and second fluid passages. Also, by having a valve included in a removably disposed heating device, easy access to the valve can be achieved when removing the exhaust device from the fluid conduit, and thus it can be the subject of maintenance or replacement. According to at least one exemplary embodiment, the valve is integrated into the exhaust device, for example, by being integrated into the first or second fluid passage, such as being integrated into the first or second conduit portion.

[0026] According to at least one exemplary embodiment, the valve is configured to control the exhaust flow to the first fluid passage and / or the exhaust flow to the second fluid passage. For example, the valve may be configured to control the exhaust flow by alternately allowing or preventing the exhaust flow to the first fluid passage. Additionally or alternatively, the valve may be configured to control the exhaust flow by allowing or preventing the exhaust flow to the second fluid passage. Additionally or alternatively, the valve may be configured to control the exhaust flow by allowing the exhaust flow to the first or second fluid passage while optionally preventing the exhaust flow to the other of the first or second fluid passages. Optionally and additionally, the valve may be configured to control the exhaust flow by alternately allowing or preventing the exhaust flow to the first or second fluid passage to the same first or second fluid passage.

[0027] According to at least one exemplary embodiment, the valve is operable between a first state that allows the exhaust flow to pass through the first fluid passage and a second state that allows at least a portion of the exhaust flow to pass through the second fluid passage.

[0028] As a result, in the first state, the exhaust can be heated by the electric heating element, while in the second state, the pressure drop is reduced because at least a portion of the exhaust flow bypasses the electric heating element by allowing it to pass through the second fluid passage. More specifically, in the first state, the valve is positioned so that the exhaust flow can flow into the first fluid passage, thereby preventing exhaust from flowing into the second fluid passage or allowing only a small amount of exhaust to flow in. For example, the valve may be configured in the first state to obstruct the flow of exhaust into the second fluid passage. As a result, all or almost all of the exhaust can flow into the first fluid passage and therefore can be heated by the electric heating element. In the second state, the valve is positioned so that at least a portion of the exhaust flow can flow into the second fluid passage. Therefore, in the second state, at least a portion of the exhaust flow can flow into the first fluid passage, or at least is made able to flow into the first fluid passage and thereby can be heated by the electric heating element. However, since at least a portion of the exhaust flow can flow into the second fluid passage, thereby bypassing the electric heating element, the pressure drop can be reduced compared to when the entire exhaust flow is guided through the first fluid passage (e.g., the first state). According to at least one exemplary embodiment, the valve is positioned in the second state to obstruct the exhaust flow into the first fluid passage. As a result, the pressure drop can be further reduced. The valve is operable to allow the exhaust flow into the first fluid passage and / or the second fluid passage, for example, by directing or guiding the exhaust flow. That is, the valve may be configured in the first state to direct or guide the exhaust flow into the first fluid passage, and in the second state to direct or guide at least a portion of the exhaust flow into the second fluid passage.

[0029] Thus, the valve may be configured to allow the flow of exhaust to the first fluid passage while preventing the flow of exhaust to the second fluid passage in the first state, and to allow the flow of exhaust to the second fluid passage and optionally to the first fluid passage in the second state.

[0030] According to at least one exemplary embodiment, the fluid conduit comprises a first conduit flange disposed upstream of the SCR catalyst, and the heating device comprises a first heating device flange, whereby, in the assembled state, the first conduit flange is connected to the first heating device flange over the entire circumference. Here, the heating device is removably disposed relative to the fluid conduit by the first conduit flange being removably connected to the first heating device flange.

[0031] As a result, a simple and effective means for removably disposing the heating device relative to the fluid conduit is provided. For example, the first conduit flange may be a flange at the end of the fluid conduit, and thus the heating device can be removably disposed or removably connected to such an end of the fluid conduit by the first conduit flange and the first heating device flange. Thus, during use, the flow of exhaust enters the fluid conduit through the heating device. In other words, the first conduit flange is connectable over the entire circumference to the first heating device flange, or the first conduit flange is configured to connect over the entire circumference to the first heating device flange.

[0032] According to at least one exemplary embodiment, the fluid conduit further comprises a second conduit flange located upstream of the first conduit flange. The heating device further comprises a second heating device flange located opposite the first heating device flange, thereby connecting the second conduit flange to the second heating device flange around its entire circumference in the assembled state. The heating device is detachably positioned relative to the fluid conduit by the first conduit flange being detachably connected to the first heating device flange and the second conduit flange being detachably connected to the second heating device flange.

[0033] As a result, another simple and effective means is provided for detachably positioning the heating device relative to the fluid conduit. In other words, the heating device is detachably positioned in the fluid conduit. Thus, when the heating device is connected to the fluid conduit in its assembled state, it can form part of the fluid passage. Here, the fluid passage can refer to the entire fluid passage or the fluid passage of the exhaust aftertreatment device. Thus, the first and second fluid passages of the heating device generally form at least their respective sub-parts of the entire fluid passage. The fluid conduit may comprise a downstream conduit section downstream of the first conduit flange and an upstream conduit section upstream of the second conduit flange. As a result, the heating device is detachably positioned in the fluid conduit such that the upstream conduit section is in fluid communication with the downstream conduit section. Thus, when the heating device is removed from the fluid conduit, the fluid conduit is divided into two distinct conduit sections, namely the upstream conduit section and the downstream conduit section. The upstream conduit section generally extends upstream from the second conduit flange, and the downstream conduit section generally extends downstream from the first conduit flange. Therefore, during use, the exhaust flow flows into the upstream conduit section and into the downstream conduit section via the heating device and the first and / or second fluid passages. In other words, the second conduit flange is connectable around the entire circumference to the second heating device flange, or the second conduit flange is configured to be connectable around the entire circumference to the second heating device flange. The downstream conduit section may include a flexible pipe. The upstream conduit section may be fluid-connected to, or included in, the outlet of the turbocharger.

[0034] According to at least one exemplary embodiment, the heating device comprises an enclosing channel wall portion extending to a first heating device flange, and first and second fluid passages are housed in the enclosing channel wall portion.

[0035] Therefore, the components of the heating device are housed within the surrounding conduit wall and can be easily removed integrally with the heating device. The surrounding conduit wall can be called the casing or housing of the heating device. Thus, in the assembled state, the surrounding conduit wall extends from the upstream conduit to the downstream conduit, or simply receives the exhaust and guides it further into the fluid conduit.

[0036] According to at least one exemplary embodiment, the exhaust aftertreatment system comprises an injector configured to inject a liquid reducing agent that supplies ammonia to an SCR catalyst. The injector is located upstream of the SCR catalyst. Generally, the injector is located between the heating device and the SCR catalyst.

[0037] According to at least one exemplary embodiment, the SCR catalyst is located in a fluid conduit downstream of the injector. Alternatively, the SCR catalyst is located downstream of the fluid conduit. For example, the fluid conduit may end at or exit from the SCR catalyst.

[0038] According to at least one exemplary embodiment, the electric heating element of the heating device is located upstream of the injector in the assembled state. Thus, the exhaust gas heated by the electric heating element can be heated before it encounters the injected reducing agent. According to at least one exemplary embodiment, in the assembled state, the injector is located between the heating device and the SCR catalyst. According to at least one exemplary embodiment, the injector is located to inject the reducing agent into the fluid conduit. According to at least one exemplary embodiment, the injector is located directly below the first conduit flange, for example, within 1 to 20 cm of the first conduit flange. This distance is the flow path distance between the injector and the first conduit flange.

[0039] According to at least one exemplary embodiment, the heating device is configured to indirectly heat the injected reducing agent with the heat of exhaust passing through an electrically heated element. Thus, the heated exhaust heats the injected reducing agent after passing through the electrically heated element.

[0040] According to at least one exemplary embodiment, the heating device is formed as a conduit bend.

[0041] As a result, the exhaust gas passing through the heating device can be further mixed, improving the heating of the exhaust gas. Furthermore, by providing an electric heating element within the heating device formed as a conduit bend, the electric heating element can be better protected from the injected reducing agent. In addition, the heating device can connect the upstream conduit section to the downstream conduit section, while the conduit bend provides a bend or curve in the fluid conduit.

[0042] According to at least one exemplary embodiment, the heating device comprises a mixing unit located in the first and / or second fluid passages. The mixing unit is configured to generate a transverse or longitudinal flow of exhaust gas. Preferably, the mixing unit is located at the end of the second fluid passage, such as at the end of the second conduit or at the end of the heating device, to facilitate mixing of the exhaust gas flow downstream of the heating device. As a result, the heated exhaust gas from the first fluid passage can be mixed with the exhaust gas from the second fluid passage in an advantageous manner.

[0043] According to at least one exemplary embodiment, the heating device is arranged so that the sprayed liquid reducing agent does not come into contact with the electric heating element during use.

[0044] For example, the electric heating element is positioned upstream of the injector at a distance that the injected liquid reducing agent cannot reach. In another example, the electric heating element is positioned behind the bend (for example, as the conduit bend described above).

[0045] According to a second aspect of the present invention, a heating device for an exhaust gas aftertreatment system that converts NOx emissions is provided. The exhaust gas aftertreatment system comprises a fluid conduit providing a fluid passage for the exhaust gas, and an SCR catalyst disposed within or downstream of the fluid conduit. The heating device comprises an electric heating element, a first fluid passage guiding the exhaust gas to the electric heating element, and a second fluid passage guiding the exhaust gas to bypass the electric heating element. The heating device is configured to be detachably positioned relative to the fluid conduit.

[0046] The effects and features of the second aspect of the present invention are largely similar to those described above in relation to the first aspect of the present invention, at least in relation to the heating device. The embodiments described in relation to the first aspect of the present invention are largely compatible with the second aspect of the present invention, at least in relation to the heating device. Therefore, for example, an electric heating device can be detachably positioned relative to the fluid conduit upstream of the SCR catalyst.

[0047] According to at least one exemplary embodiment, the heating device further comprises a first heating device flange and a second heating device flange located opposite the first heating device flange. The first heating device flange is connectable around the entire circumference to a first conduit flange of a fluid conduit, and the second heating device flange is connectable around the entire circumference to a second conduit flange of a fluid conduit.

[0048] The first and second conduit flanges of the fluid conduit have been described with reference to the first aspect of the present invention. As a result, the heating device can be detachably positioned relative to the fluid conduit. Accordingly, the heating device can be positioned relative to the fluid conduit such that, in its assembled state, the first heating device flange is connected to the first conduit flange of the fluid conduit around its entire circumference, and the second heating device flange is connected to the second conduit flange of the fluid conduit around its entire circumference. Furthermore, the first heating device flange is detachably connectable to the first conduit flange of the fluid conduit, and the second heating device flange is detachably connectable to the second conduit flange of the fluid conduit, thereby allowing the heating device to be positioned detachably relative to the fluid conduit.

[0049] According to at least one exemplary embodiment, the heating device includes at least one valve configured to control the exhaust flow in first and second fluid passages.

[0050] A third aspect of the present invention provides a heating device for an exhaust aftertreatment system that converts NOx emissions. The exhaust aftertreatment system comprises an electric heating element, a first fluid passage that guides exhaust gas to the electric heating element, and a second fluid passage that guides exhaust gas to bypass the electric heating element. The heating device is configured to be detachably positioned relative to a fluid conduit.

[0051] A third effect and feature of the present invention is largely similar to those described above in relation to the first aspect of the present invention, at least in relation to the heating device. Embodiments described in relation to the first aspect of the present invention are largely compatible with the third aspect of the present invention, at least in relation to the heating device, and some embodiments thereof are described below. Accordingly, the electric heating device can be detachably positioned relative to the fluid conduit upstream of the SCR catalyst.

[0052] According to at least one exemplary embodiment, the heating device includes at least one valve configured to control the exhaust flow in first and second fluid passages.

[0053] According to at least one exemplary embodiment, the heating device comprises a first heating device flange.

[0054] According to at least one exemplary embodiment, the heating device further comprises a second heating device flange located opposite the first heating device flange.

[0055] According to at least one exemplary embodiment, the heating device further comprises a periphery conduit wall extending between a first heating device flange and a second heating device flange. The first and second fluid passages are housed within the periphery conduit wall.

[0056] According to at least one exemplary embodiment, the heating device comprises a first conduit section including a first fluid passage and an electric heating element, and a second conduit section including a second fluid passage. The second conduit section is different from the first conduit section.

[0057] According to at least one exemplary embodiment, the first conduit section and the second conduit section are arranged concentrically.

[0058] According to at least one exemplary embodiment, the first conduit surrounds the second conduit in an annular manner, or the second conduit surrounds the first conduit in an annular manner.

[0059] The valve, the first and second heating device flanges, the surrounding conduit wall, and the first and second conduit sections have been described in relation to the first aspect of the present invention. This embodiment is applicable to the heating device of the third aspect of the present invention.

[0060] According to a fourth aspect of the present invention, a vehicle is provided that is equipped with an exhaust aftertreatment device according to a first aspect of the present invention, or a heating device according to a second or third aspect of the present invention.

[0061] The effects and features of the fourth aspect of the present invention are largely similar to those described above in relation to the first and second aspects of the present invention. The embodiments described in relation to the first aspect of the present invention are largely compatible with the fourth aspect of the present invention.

[0062] A fifth aspect of the present invention provides a method for assembling and / or detaching a heating device from a fluid conduit of an exhaust aftertreatment system for converting NOx emissions. The exhaust aftertreatment system comprises a fluid conduit providing a fluid passage for exhaust gases, an SCR catalyst located in or downstream of the fluid conduit, and an injector configured to inject a liquid reducing agent that supplies ammonia to the SCR catalyst, optionally located upstream of the SCR catalyst. The injector is located upstream of the SCR catalyst. The heating device comprises an electric heating element, a first fluid passage guiding exhaust gases to the electric heating element, and a second fluid passage guiding exhaust gases to bypass the electric heating element. The heating device is detachably connectable to the fluid conduit. The method includes assembling the heating device from the fluid conduit and / or detaching the heating device from the fluid conduit such that the heating device is located upstream of the SCR catalyst and the exhaust gas flow can be controlled to pass through the heating device via the first and / or second fluid passages.

[0063] As a result, the heating device can be easily connected to and / or easily removed from the fluid conduit. Thus, the heating device can be assembled to the fluid conduit and used to mitigate the drawback of low exhaust temperatures caused by an electric heating element that heats the exhaust flow in a first fluid passage, and to limit pressure drops in the fluid conduit by utilizing a second fluid passage that guides the exhaust to bypass the electric heating element. Furthermore, the heating device can be easily removed to access its components and fluid passages. As a result, at least the electric heating element and the first and second fluid passages become accessible, for example, for maintenance. That is, the heating device can be removed from the fluid conduit, and its components and fluid passages can be accessed, for example, for maintenance. The present invention provides a simple combination of configurations that improves the performance of the exhaust aftertreatment system after the heating device is assembled, while allowing easy access to the components and fluid passages of the heating device after it has been removed. Therefore, since the heating device is detachably positioned relative to the fluid conduit and subject to assembly and removal, an improved exhaust aftertreatment device is provided that suppresses further complexity of the heating device, while efficiently removing exhaust emissions for heating the exhaust by at least an electric heating element, and reducing pressure drop for at least a second fluid passage that bypasses the electric heating element.

[0064] The effects and features of the fifth aspect of the present invention are largely similar to those described above in relation to the first aspect of the present invention. The embodiments described in relation to the first aspect of the present invention are largely compatible with the fifth aspect of the present invention, at least in relation to the exhaust gas aftertreatment device.

[0065] According to at least one exemplary embodiment, this method is performed in an exhaust aftertreatment device according to a first aspect of the present invention.

[0066] According to at least one exemplary embodiment, the fluid conduit comprises a first conduit flange positioned upstream of the SCR catalyst, and the heating device comprises a first heating device flange. The step of assembling the heating device to the fluid passage includes connecting the first conduit flange to the first heating device flange around its entire circumference, and / or the step of removing it includes detaching the first conduit flange from the first heating device flange.

[0067] As a result, a simple and effective means is provided for assembling and detaching the heating device to and from the fluid conduit. For example, the first conduit flange may be a flange at the end of the fluid conduit, and thus the heating device can be assembled to, detachably positioned, or detachably connected to such an end of the fluid conduit by the first conduit flange and the first heating device flange. Thus, during use, exhaust flows into the fluid conduit through the heating device.

[0068] According to at least one exemplary embodiment, the fluid conduit further comprises a second conduit flange located upstream of the first conduit flange. The heating device further comprises a second heating device flange located opposite the first heating device flange. Steps to assemble the heating device to the fluid conduit include connecting the first conduit flange to the first heating device flange around its entire circumference and connecting the second conduit flange to the second heating device flange around its entire circumference, and / or steps to detach include detaching the first conduit portion from the first heating device flange and detaching the second conduit flange from the second heating device flange.

[0069] As a result, yet another simple and effective means is provided for assembling and detaching the heating device from the fluid conduit. Thus, when assembled, the heating device can form part of the fluid passage when connected to the fluid conduit. In other words, the heating device is assembled to the fluid conduit or detachably positioned in the fluid conduit. Here, the fluid passage can refer to the entire fluid passage or the fluid passage of the exhaust aftertreatment device. Thus, the first and second fluid passages of the heating device generally form at least each sub-part of the entire fluid passage. Thus, the fluid conduit may comprise a downstream conduit section downstream of the first conduit flange and an upstream conduit section upstream of the second conduit flange. As a result, the heating device is assembled to the fluid conduit or detachably positioned in the fluid conduit, connecting the downstream conduit section to the upstream conduit section. Thus, when the heating device is removed, i.e., detached from the fluid conduit, the fluid conduit is divided into two distinct conduit sections, namely the downstream conduit section and the upstream conduit section.

[0070] According to at least one exemplary embodiment, applicable to any one of the first to fifth aspects of the present invention, the exhaust aftertreatment system further comprises an emission reduction module which is a diesel particulate filter (DPF), i.e., an emission reduction module configured to remove particulate matter such as diesel exhaust particulate matter and soot from the exhaust, and / or a diesel oxidation catalyst (DOC) which is arranged and configured to convert carbon monoxide and hydrocarbons into carbon dioxide. Thus, according to at least one exemplary embodiment, the emission reduction module is a combination of a DPF and a DOC, for example, with the DOC located upstream of the DPF. According to at least one exemplary embodiment, the emission reduction module is a DPF. According to at least one exemplary embodiment, the emission reduction module is a DOC. The emission reduction module can be located, for example, upstream of a heating device.

[0071] It should be understood that an electric heating element is a heating element configured to be heated by electricity. According to at least one exemplary embodiment, the electric heating element comprises a lattice, grating, coil, or plate configured to be heated by electricity guided through the lattice, grating, coil, or plate. The electric heating element may also be in other shapes, for example, in the form of a flat or curved heating film, or may comprise a different type of heating element, for example, a resistance foam heating element. According to at least one exemplary embodiment, the electric heating element is a positive temperature coefficient PTC-based element. According to at least one exemplary embodiment, the electric heating element is based on induction heating and can be called an induction heating element. According to at least one exemplary embodiment, the operating power of the electric heating element is between 300W and 15000W, or between 1000W and 15000W. According to at least one exemplary embodiment, the operating power of the electric heating element is 12V, 24V, or 48V.

[0072] According to at least one exemplary embodiment, the reducing agent is at least one of anhydrous ammonia, aqueous ammonia, urea, aqueous urea, and diesel exhaust fluid. According to at least one exemplary embodiment, the reducing agent is urea or liquid urea. Thus, the electric heating element provides the reducing agent with the heat necessary for evaporation via the heated exhaust and the evaporating member, and, if possible, the reducing agent can be hydrolyzed to ammonia. Based on the operating power of the electric heating element, the heated exhaust can further heat the SCR catalyst.

[0073] According to at least one exemplary embodiment, the heating device is configured to maintain a temperature above 180°C downstream of the electric heating element and upstream of the SCR catalyst. This can be achieved, for example, by controlling the exhaust flow through valves to a first fluid passage and / or a second fluid passage. As a result, fouling caused by the injected reducing agent can be reduced or even eliminated. For example, the heating device may be configured to maintain a temperature above 180°C in the fluid passage downstream of the heating device and upstream of the SCR catalyst. This temperature is measured, for example, as the average temperature over a specific distance. The heating device may be configured to maintain the above temperature between 180°C and 300°C. Additionally or alternatively, the heating device is configured to maintain the temperature of the SCR catalyst between 180°C and 300°C.

[0074] According to at least one exemplary embodiment, the heating device is controlled, for example by a valve, to allow (guide or direct) the flow of exhaust gas into the first fluid passage according to the first state described above, and to begin heating the exhaust gas, in response to a measured temperature upstream of the electric heating element being below 180°C. The heating device may be further controlled to terminate or reduce the heating of the exhaust gas flow in response to a measured temperature upstream of the electric heating element exceeding 200°C, or in response to a measured temperature upstream of the heating device (and, for example, upstream of the SCR catalyst) exceeding 300°C. Such cessation or reduction of heating can be achieved by controlling a valve to allow (guide or direct) at least partially the flow of exhaust gas into the second fluid passage according to the second state described above, and to stop or at least reduce the heat supplied from the electric heating element. According to at least one exemplary embodiment, the heating device is configured to begin heating the exhaust gas in response to a measured temperature of the SCR catalyst being below 200°C or below 180°C. The heating level of an electric heating element can be controlled by changing the supply voltage to the electric heating element, or by averaging the value based on frequently switching the power on and off.

[0075] According to at least one exemplary embodiment, the heating device is configured to match the temperature downstream of the heating device and upstream of the SCR catalyst based on at least the temperature of the injected reducing agent. As a result, the temperature of the reducing agent can be incorporated into the control of the heating device.

[0076] According to at least one exemplary embodiment, the exhaust aftertreatment system includes a controller configured to control the introduction of a reducing agent into the exhaust fluid passage as a function of various exhaust parameters such as NOx, temperature, and pressure, for the purpose of controlling the NOx concentration in the exhaust. The exhaust parameters can be measured by various sensors located at various positions in the exhaust aftertreatment system. For example, NOx sensors may be located at or adjacent to the inlet and outlet of the exhaust aftertreatment system. Temperature sensors and / or pressure sensors may be located before or after the heating device or SCR catalyst. According to at least one exemplary embodiment, the heating device includes at least one various sensor or includes mounting of such sensors (there may be more).

[0077] SCR catalysts are generally configured to use a catalyst to convert nitrogen oxides (NOx) into divalent nitrogen (N2), water, and / or carbon dioxide (CO2). During use, the injected reducing agent (or the resulting ammonia) reacts on the catalyst.

[0078] The order of the method steps described in the fifth aspect of the present invention is not limited to that described herein. One or more steps may be repositioned or occur in a different order unless expressly stated without departing from the scope of the invention. However, according to at least one exemplary embodiment, the method steps are performed in the order described in the fifth aspect of the present invention.

[0079] Further advantages and features of this disclosure are disclosed and illustrated in the following description and accompanying drawings.

[0080] With reference to the attached drawings, the following examples of embodiments of the present invention will be described in more detail. [Brief explanation of the drawing]

[0081] [Figure 1] This is a schematic side view of a vehicle equipped with an exhaust aftertreatment device according to an exemplary embodiment of the present invention. [Figure 2A] This is a schematic cross-sectional view of an exhaust gas aftertreatment device including a heating device according to an exemplary embodiment of the present invention. [Figure 2B] Figure 2A is a schematic cross-sectional view of the first and second conduit sections of the heating device. [Figure 3A] This provides a schematic example of how a heating device may be detachably positioned relative to a fluid conduit and how it may be assembled / disassembled, applicable to exemplary embodiments of the present invention. [Figure 3B] This provides a schematic example of how a heating device may be detachably positioned relative to a fluid conduit and how it may be assembled / disassembled, applicable to exemplary embodiments of the present invention. [Figure 4] This is a schematic cross-sectional view of an exhaust gas aftertreatment device including a heating device according to an exemplary embodiment of the present invention. [Figure 5] This is a schematic cross-sectional view of an exhaust aftertreatment device including a heating device according to another exemplary embodiment of the present invention. [Figure 6] This is a schematic cross-sectional view of an exhaust aftertreatment device including a heating device according to yet another exemplary embodiment of the present invention. [Figure 7] This flowchart shows the steps of a method according to an exemplary embodiment of the present invention. [Modes for carrying out the invention]

[0082] Referring to Figure 1, an exhaust aftertreatment device 20 and a heating device 38 of the type disclosed herein are beneficial, and a vehicle 1 is shown here exemplified as a heavy truck 1. However, the exhaust aftertreatment device 20 and / or heating device 38 can also be similarly implemented in other types of vehicles, such as buses, light trucks, construction machinery, passenger cars, and marine applications. Although the vehicle 1 in Figure 1 is equipped with an engine 10 which is a diesel engine 10, the vehicle 1 may also be a hybrid vehicle further comprising an electromechanical unit (not shown) according to at least one exemplary embodiment. The diesel engine 10 is generally powered by diesel fuel contained in a fuel tank, and the electromechanical unit is generally powered by electricity supplied from at least one energy storage device or converter, such as a battery or a fuel cell.

[0083] In Figure 1, the vehicle 1 further comprises an exhaust aftertreatment system 20 for purifying exhaust gases emitted from at least the diesel engine 10. The exhaust aftertreatment system 20, as best seen in the enlarged view of Figure 1, comprises at least an SCR catalyst 32 and a heating device 38 for heating the exhaust gases before the SCR catalyst 32. The SCR catalyst 32 is arranged and configured to use the catalyst to convert nitrogen oxides, also known as NOx, into divalent nitrogen N2, water, and / or carbon dioxide CO2. Optionally, the exhaust aftertreatment system 20 further comprises an injector configured to inject a liquid reducing agent that supplies ammonia to the SCR catalyst 32. The injector is generally located upstream of the SCR catalyst 32 and downstream of the heating device 38. The reducing agent, preferably anhydrous ammonia, aqueous ammonia, urea, aqueous urea, or a diesel exhaust fluid solution, is added to the engine exhaust by the injector and adsorbed onto the catalyst of the SCR catalyst 32.

[0084] Figure 2A shows the exhaust aftertreatment device 20 of Figure 1 in more detail. The exhaust aftertreatment device 20 comprises a fluid conduit 21 that provides a fluid passage for the exhaust. The exhaust aftertreatment device 20 further comprises an SCR catalyst 32 located downstream of the fluid conduit 21. In Figure 2, this is illustrated so that the fluid conduit 21 enters and terminates in the SCR catalyst 32. In addition, to supply ammonia to the SCR catalyst 32, the exhaust aftertreatment device may also comprise an injector 34 located upstream of the SCR catalyst 32 and configured to inject a liquid reducing agent that supplies ammonia to the SCR catalyst 32, as described above. The reducing agent is, for example, urea. The exhaust aftertreatment device 20 further comprises a heating device 38 located upstream of the SCR catalyst 32 and upstream of the injector 34 and configured to heat the exhaust before the SCR catalyst 32. The heating device 38 comprises an electric heating element 40, illustrated here as a lattice or grating 40, through which the exhaust passes and is heated. In Figure 2, the exhaust fluid passage inside the heating device 38 is divided into a first fluid passage 26A that guides the exhaust to the electric heating element 40, and a second fluid passage 26B that guides the exhaust so as to bypass the electric heating element 40.

[0085] In Figure 2A, the heating device 38 comprises a first conduit section 28A including a first fluid passage 26A and an electric heating element 40, and a second conduit section 28B including a second fluid passage 26B. Therefore, the second conduit section 28B is different from the first conduit section 28A. That is, the first conduit section 28A is defined by a conduit wall that surrounds the first fluid passage 26A around its entire circumference, and the second conduit section 28B is defined by a conduit wall that surrounds the second fluid passage 26B around its entire circumference. In Figure 2A, as can be seen from Figure 2B, the first conduit section 28A has a cross-section that is formed in an annular shape or as a ring, or that crosses the longitudinal direction L of the exhaust aftertreatment device 20. Similarly, as can be seen in Figure 2B, the second conduit section 28B has a cross-section that traverses the longitudinal direction L of the circular exhaust aftertreatment device 20. Also, as can be seen in both Figures 2A and 2B, the first conduit section 28A surrounds the second conduit section 28B in an annular manner so that the first conduit section 28A and the second conduit section 28B are arranged concentrically.

[0086] The exhaust aftertreatment device 20, more specifically the heating device 38 in Figure 2A, includes a valve 41 configured to control the exhaust flow in the first and second fluid passages 26A and 26B by controlling the exhaust flow to the first and second conduit sections 28A and 28B. The valve 41 is operable between a first state in which the exhaust flow is allowed to pass through the first conduit section 28A and the first fluid passage 26A, and a second state in which at least a portion of the exhaust is allowed to pass through the second conduit section 28B and the second fluid passage 26B. In Figure 2A, the second state is represented by the valve 41 in dashed form. Therefore, in the first state in Figure 2, the valve 41 is positioned to obstruct the exhaust flow in the second fluid passage 26B by covering the cross-section of the second conduit section 28B, preventing the exhaust flow from passing through the second conduit section. As a result, the exhaust flow is allowed to pass through the first conduit section 28A, the first fluid passage 26A, and the electric heating element 40. Generally, the electric heating element 40 covers the entire cross-section of the first conduit 28A, thereby preventing the exhaust flow inside the first conduit 28A from bypassing the electric heating element 40. Similarly, in the second state, the valve 41 is positioned to allow exhaust flow in the second fluid passage 26B by opening at least a portion of the cross-section of the second conduit 28B, so that at least a portion of the exhaust flow can pass through the second conduit 28B and the second fluid passage 26B. As a result, the exhaust flow is separated between the first conduit 28A and the second conduit 28B, and the pressure drop induced throughout the heating device 38 can be reduced compared to the first state.

[0087] Accordingly, the valve 41 in Figure 2A is configured such that, in the first state, it allows the exhaust flow to flow into the first fluid passage 26A while preventing the exhaust flow from flowing into the second fluid passage 26B, and in the second state, it allows the exhaust flow to pass through the second fluid passage 26B and optionally through the first fluid passage 26A. For example, in the first state, the valve is configured to direct or guide the exhaust flow towards the first fluid passage 26A while preventing the exhaust flow into the second fluid passage 26B. In the second state, the valve is configured to direct or guide the exhaust flow towards the second fluid passage 26B and optionally through the first fluid passage 26A.

[0088] In Figure 2A, the heating device 38 is detachably positioned relative to the fluid conduit 21. Therefore, the heating device 38 can be removed from the fluid conduit 21 and, for example, can be subject to maintenance or replacement of components. For this purpose, the fluid conduit 21 comprises a first conduit flange 21A located upstream of the SCR catalyst 32, and a second conduit flange 21B located upstream of the first conduit flange 21A. As a result, the fluid conduit 21 is divided into two conduit sections, namely a downstream conduit section 22 and an upstream conduit section 23. In Figure 2A, the downstream conduit section 22 extends downstream from the first conduit flange 21A to the SCR catalyst 32, and the upstream conduit section 23 extends upstream from the second conduit flange 21B.

[0089] Similarly, the heating device 38 comprises a first heating device flange 39A and a second heating device flange 39B located on the opposite side of the first heating device flange 39A. The heating device 38 is detachably positioned relative to the fluid conduit 21 by means of screws or clamps, for example, the first conduit flange 21A being detachably connected to the first heating device flange 39A, and the second conduit flange 21B being detachably connected to the second heating device flange 39B, for example, by screws or clamps. Therefore, the heating device 38 can be removed or put into a detached state by detaching the first conduit flange 21A from the first heating device flange 39A and the second conduit flange 21B from the second heating device flange 39B. Such a state is shown in Figure 3A, where the heating device 38 is separated from the fluid conduit 21 and the downstream conduit section 22 is separated from the upstream conduit section 23. Such a detached state can be observed during the installation of the heating device 38 to the fluid conduit 21, or during maintenance of the heating device 38 and / or the fluid conduit 21. Subsequently, the heating device 38 may be assembled, as shown in Figure 3B. Thus, in the assembled state in which the heating device 38 is installed on the fluid conduit 21, the first conduit flange 21A is connected to the first heating device flange 39A around its entire circumference, and the second conduit flange 21B is connected to the second heating device flange 39B around its entire circumference.

[0090] However, it should be noted that the upstream conduit section 23 is not required, and the heating device 38 may be detachably positioned only relative to the downstream conduit section 22.

[0091] Returning to Figure 2A, in which the heating device 38 is assembled to the fluid conduit 21 as described above, the heating device 38 includes a perimeter conduit wall 39 extending from the second heating device flange 39B to the first heating device flange 39A. In Figure 2, the first and second fluid passages 26A, 26B, and therefore the first and second conduit sections 28A, 28B, are housed in the perimeter conduit wall 39. The perimeter conduit wall 39 can be called the casing or housing of the heating device 38. That is, the electric heating element 40 is housed inside the heating device 38.

[0092] The exhaust aftertreatment device 20 generally operates as follows: Exhaust (to be purified) from the diesel engine flows into the exhaust aftertreatment device 20 via the upstream conduit 23, passes through the heating device 38, and thereby the exhaust flow meets the valve 41. Depending on the position of the valve 41, the exhaust flow is directed or guided to the first fluid passage 26A and optionally the second fluid passage 26B by enabling and / or obstructing the exhaust flow through the first and second conduits 28A, 28B. For example, if the valve 41 is in the first position, all exhaust flow to the first conduit 28A is enabled (for example, by being directed or guided), thereby the exhaust is heated by the electric heating element 40. Since all exhaust flow is guided through the electric heating element 40, the pressure drop induced throughout the heating device 38 is relatively large. The pressure drop induced when the valve 41 is in the first position can be called the first pressure drop. Subsequently, or before placing the valve 41 in the first state, the valve 41 can be placed in the second state, allowing at least a portion of the exhaust flow to pass through the second conduit section 28B via the second fluid passage 26B. Therefore, since there is no electric heating element in the second conduit section 28B, the pressure drop induced throughout the heating device 38 is smaller compared to when the valve 41 is placed in the first state. The pressure drop induced when the valve 41 is placed in the second state can be called the second pressure drop. The second pressure drop is smaller than the first pressure drop. Generally, since the first fluid passage 26A is also available when the valve 41 is placed in the second state, the pressure drop induced throughout the heating device 38 is based on the combined effect of the exhaust flow passing through the first and second conduit sections 28A and 28B.

[0093] As shown in Figure 2A, the electric heating element 38 is a lattice or grating, and therefore the exhaust flow is heated as it passes through the lattice or grating. Note that the electric heating element may be arranged in a different way, for example, the electric heating element may include a heating coil or heating foam, and the exhaust may be heated by passing across the heating surface of the heating coil or heating foam.

[0094] After passing through the heating device 38, the exhaust gas flow, at least partially heated, continues to flow along the fluid conduit 21 to the downstream conduit section 22, for example, to the location where a reducing agent is injected by an injector (not shown). Thus, the injected reducing agent is partially mixed with the heated exhaust gas flow and the heat provided by the electric heating element 40. The reducing agent (if necessary) and exhaust gas then flow into the SCR catalyst 32 for catalytic reduction of NOx, after which the purified exhaust gas is discharged from the exhaust gas aftertreatment device 20 or further purified by a downstream process.

[0095] Figure 4 shows an alternative heating device 138 for the exhaust aftertreatment device 120. The heating device 138 can be placed, for example, in the fluid conduit 21 corresponding to the embodiment shown in Figure 2A, and therefore, in principle, functions similarly to the embodiment shown in Figure 2. However, the heating device 138 in Figure 4 omits the valves configured to control the exhaust flow in the first and second fluid passages 26A and 26B. Therefore, the exhaust flow passing through the first conduit section 128A, which includes the first fluid passage 26A and the electric heating element 140, and the exhaust flow passing through the second conduit section 128B, which includes the second fluid passage 26B, are divided into two fluid passages according to the basic flow principle. Therefore, the amount of heat added to the exhaust can be controlled over a wide range by the power of the electric heating element 140 compared to the embodiment shown in Figure 2A. Also, the overall pressure drop in the heating device 138 does not change much compared to the embodiment in Figure 2 because there are no valves obstructing the flow passing through the second conduit section 128B.

[0096] Returning to Figure 5, which shows an exhaust aftertreatment device 220 that corresponds at least in part to the exhaust aftertreatment device 20 of Figure 2A, it functions in principle similarly to the embodiment shown in Figure 2A, by including at least a valve 241 configured to control the exhaust flow in the first and second fluid passages 26A, 26B. However, for the heating device 238 of Figure 5, the valve 241 is located outside the heating device 238 and instead is included in the fluid conduit 21 upstream of the heating device 238. Here, the valve 241 is mounted to rotate relative to the conduit wall of the fluid conduit 21 and is operable between a first state that allows the exhaust flow to flow into a first conduit section 228A containing the first fluid passage 26A, and a second state that allows at least a portion of the exhaust flow to flow into a second conduit section 228B containing the second fluid passage 26B. The valve 241 has a central opening surrounded all around by a closure. In Figure 5, which shows the first state of valve 241, the central opening coincides with the first conduit section 228A, thereby allowing the exhaust flow to pass through the first fluid passage 26A and the electric heating element 240, while the closed section coincides with the second conduit section 228B, thereby preventing the exhaust flow from passing through the second fluid passage 26B (for example, by directing or guiding it). In the second state, represented by the dashed line of valve 241, valve 241 rotates toward the conduit wall of the fluid conduit 21. Thus, here valve 241 is positioned to allow the exhaust flow in the second conduit section 228B through the second fluid passage 26B, by no longer obstructing the flow to the second conduit section 228B. As a result, the exhaust flow is separated between the first conduit section 228A and the second conduit section 228B, and the pressure drop induced throughout the heating device 238 can be reduced compared to the first state. Furthermore, in Figure 5, the second conduit section 228B has a cross-section that traverses the longitudinal direction of the exhaust aftertreatment device 220, which is formed in an annular or ring shape. Similarly, the first conduit section 228A has a cross-section that traverses the longitudinal direction of the circular exhaust aftertreatment device 220.Furthermore, since the second conduit section 228B and the first conduit section 228A are arranged concentrically in Figure 5, the second conduit section 228B surrounds the first conduit section 228A in an annular manner.

[0097] Figure 6 shows yet another embodiment of the heating device 338 of the exhaust aftertreatment device 320. The heating device 338 can be located, for example, in the fluid conduit 21 corresponding to the embodiment shown in Figure 2, and is very similar to the embodiment shown in Figure 4, as there are no valves configured to control the exhaust flow in the first and second fluid passages 26A, 26B. However, in Figure 6, the first conduit section 328A, which includes the first fluid passage 26A, is defined by the surrounding conduit wall 339 (similar to the surrounding conduit wall 39 in the embodiment shown in Figure 2A) and the outer surface of the electric heating element 340. Similarly, the second conduit section 328B, which includes the second fluid passage 26B, is defined by the external structure of the electric heating element 340. Since the electric heating element 340 is located in the center of the heating device 338, the second conduit section 328B has a cross section that is annular or ring-shaped, or that crosses the longitudinal direction of the exhaust aftertreatment device 320. Similarly, the first conduit section 328A has a cross-section that spans the longitudinal direction of the exhaust aftertreatment device 320, having a circular or any other periphery defined by the external structure of the electric heating element 340. The second conduit section 328B surrounds the first conduit section 328A in an annular manner, as the second conduit section 328B and the first conduit section 328A are concentrically arranged in Figure 6. The periphery conduit wall section 339 is formed as a bulge compared to the fluid passage 21, allowing the exhaust flow to bypass the electric heating element 340 in an effective manner. Furthermore, the bulge-shaped periphery conduit wall section 339 promotes mixing of the exhaust flow downstream of the heating device 338, as the exhaust flow in the second conduit section 238B is forcibly bent when it bypasses the electric heating element 349.

[0098] It should be understood that the heating devices 138, 238, and 338 in Figures 4-6 are generally detachably positioned relative to the fluid conduit 21 by first and second conduit flanges and corresponding first and second heating device flanges, as described in the embodiment of Figure 2A.

[0099] A method for assembling and / or detaching a heating device from the fluid conduit of an exhaust aftertreatment system for converting NOx emissions will be described in detail here with reference to Figure 7. Thus, the exhaust aftertreatment system can be as shown in Figures 2A, 2B, 3A, 3B, 4, 5, and 6 in relation to the heating device. Thus, the exhaust aftertreatment system comprises a fluid conduit providing a fluid passage for the exhaust, an SCR catalyst located in or downstream of the fluid conduit, and an injector configured to inject a liquid reducing agent that supplies ammonia to the SCR catalyst, optionally located upstream of the SCR catalyst. The injector is located upstream of the SCR catalyst. The heating device generally comprises an electric heating element, a first fluid passage guiding the exhaust to the electric heating element, and a second fluid passage guiding the exhaust to bypass the electric heating element. The heating device is detachably connectable to the fluid conduit.

[0100] In the first step S10, the heating device is assembled to the fluid conduit such that it is positioned upstream of the SCR catalyst, thereby allowing the exhaust flow to be controlled to pass through the heating device via the first and / or second fluid passages.

[0101] As described with reference to the embodiments in Figures 2A, 2B, 3A, and 3B, the fluid conduit may include a first conduit flange located upstream of the SCR catalyst, and the heating device may include a first heating device flange. Accordingly, the first assembly step S10 may optionally include a first substep S12 for connecting the first conduit flange to the first heating device flange around its entire circumference. Also, as previously described, the fluid conduit may further include a second conduit flange located upstream of the first conduit flange, and the heating device may further include a second heating device flange located opposite the first heating device flange. Accordingly, the first assembly step S10 may include a first substep S12 for connecting the first conduit flange to the first heating device flange around its entire circumference, and a second substep S14 for connecting the second conduit flange to the second heating device flange around its entire circumference.

[0102] In a second step S20, which can be performed following the first step S10 and either of the optional substeps S12 or S14, or in place of or before the first step S10 and either of the optional substeps S12 or S14, the heating device is removed from the fluid conduit. Similar to the first and second substeps S12 and S14, the second removal step S20 may include a third substep S22 for separating the first conduit flange from the first heating device flange, and a fourth substep S24 for separating the second conduit flange from the second heating device flange.

[0103] It should be understood that the present invention is not limited to the embodiments described above and illustrated. Rather, those skilled in the art will recognize that many changes and modifications can be made within the scope of the appended claims. For example, the electric heating element may be powered via an electrical connection integrated with the heating device housing. For example, the operating power of the electric heating element may be between 300W and 15000W. Furthermore, the exhaust aftertreatment device may be used to convert NOx emissions from the exhaust of engines other than diesel engines. For example, the exhaust aftertreatment device may be used to convert NOx emissions from the exhaust of internal combustion engines based on CNG (compressed natural gas), LPG (liquefied pressurized gas), DME (dimethyl ether), and / or H2 (hydrogen).

[0104] Furthermore, modifications of the disclosed embodiments can be understood and achieved by those skilled in the art who practice the claimed concept of the invention, based on a review of the drawings, disclosures, and appended claims. In the claims, the term “equips” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude plurals. The mere fact that certain methods are described in mutually distinct dependent claims does not imply that combinations of these methods cannot be used advantageously.

Claims

1. An exhaust aftertreatment device (20, 120, 220, 320) for purifying exhaust gas, comprising: a fluid conduit (21) providing a fluid passage for the exhaust; an SCR catalyst (32) disposed within or downstream of the fluid conduit; a heating device (38, 138, 238, 338) disposed upstream of the SCR catalyst for heating the exhaust gas, the heating device comprising an electric heating element (40, 140, 240, 340), a first fluid passage (26A) for guiding the exhaust gas to the electric heating element, and a second fluid passage (26B) for guiding the exhaust gas to bypass the electric heating element, the heating device being removably disposed with respect to the fluid conduit; An exhaust after-treatment device (20, 120, 220, 320) comprising:

2. The heating device (38, 138, 238, 338) a first conduit portion (28A, 128A, 228A, 338A) containing said first fluid passage (26A) and said electric heating element (40, 140, 240, 340); a second conduit portion (28B, 128B, 228B, 328B) including the second fluid passage (26B); Equipped with the second conduit portion is different from the first conduit portion; The exhaust aftertreatment device (20, 120, 220, 320) of claim 1.

3. The first conduit portion (28A, 128A, 228A, 328A) and the second conduit portion (28B, 128B, 228B, 328B) are concentrically arranged. The exhaust after-treatment device according to claim 2 .

4. The first conduit portion (28A, 128A) annularly surrounds the second conduit portion (28B, 128B), or the second conduit portion (228B, 328B) annularly surrounds the first conduit portion (228A, 328A). The exhaust after-treatment device according to claim 2 .

5. and at least one valve (41, 241) configured to control the flow of exhaust gas in the first and second fluid passages (26A, 26B). The exhaust aftertreatment device (20, 220) of claim 1.

6. The heating device (38) is provided with the valve (41), The exhaust aftertreatment device (20) of claim 5.

7. the valve (41, 241) is operable between a first state that allows exhaust flow to pass through the first fluid passage (26A) and a second state that allows at least a portion of the exhaust flow to pass through the second fluid passage (26B); The exhaust aftertreatment device (20, 220) of claim 5.

8. The fluid conduit (21) comprises a first conduit flange (21A) disposed upstream of the SCR catalyst (32); The heating device (38, 138, 238, 338) comprises a first heating device flange (39A); Thus, in an assembled state, the first conduit flange is connected to the first heating device flange over the entire circumference, at least the first conduit flange is removably coupled to the first heater flange, thereby removably positioning the heater relative to the fluid conduit; The exhaust aftertreatment device (20, 120, 220, 320) of claim 1.

9. The fluid conduit (21) further comprises a second conduit flange (21B) disposed upstream of the first conduit flange (21A); The heater (38, 138, 238, 338) comprises a second heater flange (39B) disposed opposite the first heater flange (39A); Thus, in the assembled state, the second conduit flange is connected to the second heating device flange over the entire circumference, the first conduit flange is removably coupled to the first heater flange and the second conduit flange is removably coupled to the second heater flange, thereby removably positioning the heater relative to the fluid conduit. The exhaust aftertreatment device (20, 120, 220, 320) of claim 8.

10. the heating device (38, 138, 238, 338) includes a peripheral conduit wall (39, 339) extending to the first heating device flange (39A); the first and second fluid passages (26A, 26B) are contained within the peripheral conduit wall; The exhaust aftertreatment device (20, 120, 220, 320) of claim 8.

11. A heating device (38, 138, 238, 338) for an exhaust aftertreatment device (20, 120, 220, 320) for converting NOx emissions, comprising: The exhaust aftertreatment device includes a fluid conduit (21) providing a fluid passage for exhaust gas, and an SCR catalyst (32) disposed within or downstream of the fluid conduit; the heating device comprises an electric heating element (40, 140, 240, 340), a first fluid passage (26A) for guiding the exhaust air to the electric heating element, and a second fluid passage (26B) for guiding the exhaust air to bypass the electric heating element, the heating device being configured to be removably positioned relative to the fluid conduit; Heating device (38, 138, 238, 338).

12. A first heater flange (39A); a second heater flange (39B) disposed opposite the first heater flange; Further comprising: the first heater flange is connected to a first conduit flange (21A) of the fluid conduit around its entire circumference, and the second heater flange is connected to a second conduit flange (21B) of the fluid conduit around its entire circumference; The heating device according to claim 11.

13. A vehicle (1) equipped with an exhaust after-treatment device (20, 120, 220, 320) as described in claim 1, or a heating device (38, 138, 238, 338) as described in claim 11.

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