Exhaust duct with bypass and device for regulating bypass mass flow

Abstract

The present application relates to an exhaust gas line with a bypass and a device for adjusting the bypass mass flow. The invention relates to an exhaust gas line (1) for conducting exhaust gases of an internal combustion engine, wherein the exhaust gas line (1) has at least a main flow duct (11) and a bypass (12) and an adjustable throttle flap (3) in the main flow duct (11), wherein the throttle flap (3) is pivotable from an open position, in which the main flow duct (11) is released, and a closed position, in which the main flow duct (11) is blocked, wherein a bypass flap (31) is kinematically connected to the throttle flap (3) such that, when the bypass (12) is closed, the throttle flap (3) is in its open position and, when the bypass (12) is completely released, the throttle flap (3) is in its closed position.

Description

[0001] The present invention relates to an exhaust gas conduit for guiding exhaust gas from an internal combustion engine, wherein the exhaust gas conduit has at least a main flow conduit and a bypass, and an adjustable throttle valve in the main flow conduit, wherein the throttle valve is pivotable from an open position and a closed position, wherein in the open position the main flow conduit is released and in the closed position the main flow conduit is blocked.

[0002] This type of exhaust gas duct is known from the prior art. A device is known from DE 10 2010 049 957 A1, by means of which fuel can be broken down into shorter carbon chains by pyrolysis, and the exhaust gas can be heated by the subsequent oxidation of the carbon chains to provide the exhaust gas temperature level required for effective reduction of nitrogen oxides during cold starts of the internal combustion engine. Such devices are typically arranged in a bypass parallel to the exhaust duct of the internal combustion engine, and a portion of the mass flow of the exhaust gas is directed through this device.

[0003] Catalysts used for selective catalytic reduction (SCR) (so-called SCR catalysts) are used to reduce nitrogen oxide emissions from diesel engines, combustion equipment, waste incineration equipment, industrial equipment, etc. For this purpose, a reducing agent is injected into the exhaust system using metering equipment. Ammonia or ammonia solution, or other reducing agents, are used as the reducing agent.

[0004] Because carrying ammonia in vehicles is of paramount safety importance, urea is typically used in the form of an aqueous solution with a urea content of 32.5%, in particular, according to DIN 70070. In exhaust gases, urea decomposes into gaseous ammonia and CO2 at temperatures above 150 degrees Celsius. The parameters for urea decomposition are primarily time (evaporation time and reaction time), temperature, and the droplet size of the injected urea solution. In these SCR catalysts, nitrogen oxide emissions are reduced by approximately 90% through selective catalytic reduction.

[0005] The term reducing agent solution or reducing agent includes any reducing agent suitable for selective catalytic reduction, for which urea solution according to DIN 70070 is preferred.

[0006] In known exhaust aftertreatment systems for selective catalytic reduction (SCR), the relatively low temperature of the exhaust gas (e.g., during a cold start of an internal combustion engine, i.e., before reaching the engine's operating temperature) can adversely affect the function of the SCR catalyst.

[0007] After urea in aqueous solution is injected into the exhaust duct, ammonia (NH3) must first be formed before the SCR reaction can proceed. Here, reduced ammonia is released through thermodynamic decomposition (thermal decomposition) of urea and hydrolysis to produce isocyanate. In the first reaction (thermal decomposition), urea is converted into ammonia (NH3) and isocyanate (HNCO) due to the influence of temperature. In the second step, hydrolysis occurs in the presence of water, during which isocyanate is also converted into ammonia, while carbon dioxide (CO2) is generated. Relatively low temperatures (e.g., the temperature during a cold start of an internal combustion engine) may slow down the progress of these reactions.

[0008] Therefore, in order to ensure the effectiveness of selective catalytic reduction in the exhaust duct, the temperature of the exhaust gas must be raised to a certain level (approximately 200°C) as quickly as possible during cold start.

[0009] A known drawback of the equipment is that the entire reaction chamber is first electrically heated to raise the pyrolysis reactor to a temperature level at which the introduced fuel can be automatically oxidized. For evaporation, the nonwoven fabric must be heated by radiant heat provided by the pyrolysis reactor. This requires very high temperatures in the pyrolysis reactor, necessitating very high electrical power. Because the current flowing through the honeycomb structure of the pyrolysis reactor is extremely high, it can potentially damage the honeycomb structure and electrical connections within the reaction chamber.

[0010] Another drawback of the prior art is that, by means of the throttling valves typically used in the bypass of receiving equipment, it is impossible or only insufficient to maintain a constant portion of the mass flow of the exhaust gas being guided through the equipment, which is necessary for the effective use of the equipment.

[0011] Another drawback of the known equipment is that it occupies a large installation space because a bypass with exhaust gas heating equipment must be installed next to the main exhaust duct.

[0012] Therefore, the object of the present invention is to improve the exhaust gas duct, which in particular has an internal combustion engine exhaust gas heating device with a pyrolysis reactor, thereby overcoming the above-mentioned disadvantages and reducing the required installation space.

[0013] According to the invention, this objective is achieved through an exhaust gas duct according to the invention. Advantageous improvements of the invention are presented herein.

[0014] An exhaust gas duct for guiding exhaust gas from an internal combustion engine, wherein the exhaust gas duct has at least a main flow duct and a bypass, and an adjustable throttle valve in the main flow duct, wherein the throttle valve is pivotable from an open position and a closed position, wherein in the open position the main flow duct is open and in the closed position the main flow duct is blocked, and particularly advantageously in the exhaust gas duct, the bypass valve is kinematically connected to the throttle valve such that when the bypass is closed the throttle valve is in its open position and when the bypass is fully released the throttle valve is in its closed position.

[0015] In the sense of the invention, the term "closed position" (where the main flow channel is blocked) includes both complete blockage of the main flow channel and the maximum throttling effect where the main flow channel is not necessarily hermetically sealed.

[0016] Preferably, the throttling valve and the bypass valve are formed from a single component, particularly from a casting or injection molded part of the same material.

[0017] Particularly preferably, the throttling valve and the bypass valve can pivot synchronously about a common axis of rotation in a manner that is not rotatable relative to each other.

[0018] Preferably, a servo motor is provided, by means of which the throttle valve and the bypass valve are pivoted. Therefore, the servo motor is used to adjust the throttle valve and the bypass valve kinematically connected to the throttle valve.

[0019] Preferably, the bypass route is formed as an integral part of the main flow duct. More preferably, the bypass route is formed as a flow duct within a sub-sector (Teilsektor) that forms an exhaust gas duct in its cross-section, particularly as a circular portion of an exhaust gas duct with a circular cross-section. The duct leading to the pyrolysis reactor can be implemented using a simple plate or an additional pipe in or on the exhaust gas duct.

[0020] In a preferred embodiment, a bypass is provided to an exhaust gas heating device having at least one pyrolysis reactor, wherein at least a portion of the mass flow of exhaust gas from the internal combustion engine is introduced into the pyrolysis reactor via the bypass, wherein at least one nonwoven fabric (Vlies) is connected upstream of the pyrolysis reactor, the nonwoven fabric being fueled, wherein the fuel evaporates and undergoes an exothermic reaction in the pyrolysis reactor with the oxygen component of the exhaust gas mass flow introduced into the pyrolysis reactor via oxidation, particularly to provide a sufficiently high pyrolysis temperature, wherein the exhaust gas heated by means of the device is introduced into the main flow duct downstream of the exhaust gas heating device.

[0021] Fuel, particularly vehicle fuel or diesel fuel, is supplied to the system. The fuel decomposes in a pyrolysis reactor and is completely oxidized provided there is sufficient oxygen. Gases escape from the pyrolysis reactor at approximately 750°C. Under higher fuel supply conditions, the system operates in an oxygen-deficient environment. The reaction products are primarily CO and H2, along with unburned hydrocarbons. H2 and CO have very low ignition temperatures, known as "light-off temperatures," at the downstream oxidation catalyst in the exhaust gas system. This allows the oxidation catalyst to release heat even at low exhaust gas temperatures of 200°C, maintaining the overall temperature above 200°C. Consequently, even in the internal combustion engine's operating range below 200°C, the temperature at the SCR system remains above 200°C, enabling highly efficient denitrification.

[0022] There are two different modes required for heating the exhaust gas system or the main oxidation catalyst (main DOC).

[0023] - Lean "Lambda>>1" operation: This involves both heating the main DOC to the ignition temperature of the pyrolysis gas and maintaining a) the pyrolysis reactor itself and b) the main DOC and SCR at sufficiently high reaction temperatures for effective denitrification; and

[0024] - Fett "Lambda<<1" operation: This is used to generate pyrolysis gases, which are then first oxidized in the main DOC, releasing heat here. This heat is many times greater than the energy of the "Lambda>>1" operation. In this way, the entire exhaust gas system can be heated very quickly so that denitrification can begin as early as possible after engine start.

[0025] Lambda represents the air-to-water ratio.

[0026] In the "Lambda<<1" operation (surplus operation, also known as heating operation), oxidation within the pyrolysis reactor itself occurs in a very regionally distributed manner, meaning that the internal catalyst receives excess fuel locally or in a specific area, or even throughout the entire area. However, this fuel cannot be completely burned locally because the exhaust gas supplied to the pyrolysis reactor is distributed through multiple orifices. As a result, only as much fuel as is locally present in the exhaust gas is locally oxidized. In the "Lambda=0.1" operation with a heating power of 25 kW per pyrolysis reactor, only 10% of the fuel is oxidized in the pyrolysis reactor, while the remaining 90% is converted into shorter carbon chains through pyrolysis.

[0027] Insufficient exhaust gas mass flow will cause the pyrolysis reactor to cool down, while excessive flow (Lambda > 0.3, or even 1.0) will cause the pyrolysis reactor to overheat and melt. For cases with very low exhaust gas mass flow, the bypass must have high flow resistance, that is, the bypass must have a higher flow resistance than a fully open exhaust valve in the main exhaust duct parallel to the pyrolysis reactor.

[0028] In "Lambda >> 1" operation (lean operation, also known as DOC operation), all fuel is oxidized in the pyrolysis reactor. Depending on the operating conditions, the Lambda value can range from 1.5 to 10. Oxygen is in excess. Fuel is supplied to the top of a nonwoven fabric positioned directly in front of the pyrolysis reactor, where it spreads and evaporates during the process. Because oxygen is in excess, almost all of the fuel is converted into heat through oxidation. The correct cooling power is set by the supplied exhaust gas mass flow. Here, the opposite is true: too much exhaust gas mass flow will cool the pyrolysis reactor, while too little (Lambda < 1.5, or even 1.0) will cause the reactor to overheat and melt. For this relatively high exhaust gas mass flow, the bypass must have relatively low flow resistance to prevent the engine from experiencing excessive exhaust back pressure.

[0029] The bypass mass flow is supplied to the pyrolysis reactor inside the main exhaust pipe, which has an internal "airtight" separation. This can be achieved and controlled by a combination throttling valve with a bypass valve.

[0030] By utilizing the dual-acting exhaust valve according to the invention, the bypass exhaust gas flow can be safely regulated in two operating modes using only this valve. Here, the engine is not subjected to high back pressure, and the bypass maintains low flow resistance through the pyrolysis reactor.

[0031] By utilizing a combined throttling valve in the main exhaust pipe, flow can be effectively introduced into both systems, using only one existing exhaust valve. Therefore, only one valve needs to be driven and adjusted. The continuously adjustable angles of the combined throttling valve with bypass valve now produce different exhaust gas flow distributions in the split flow.

[0032] A particular advantage here is that the mass flow through the pyrolysis reactor can be set to zero by completely closing the bypass valve. This is an emergency stop function in case the pyrolysis reactor overheats. In this way, the oxygen content in the pyrolysis reactor is reduced to almost zero, and although the fuel in the pyrolysis reactor can evaporate, it does not generate heat due to oxidation.

[0033] Specifically, the bypass valve on the throttle valve can be spring-loaded and secured to the valve shaft, so that when the bypass is blocked and completely closed, the bypass valve remains stationary and only the throttle valve can continue to rotate. This continued rotation can continue until the main exhaust duct is also almost completely closed. This function can be used as a braking valve or an exhaust back pressure valve.

[0034] Using this bypass valve, a large gap can be created between the bypass valve and the exhaust valve sleeve (Abgasklappengehäuserohr). When the bypass valve passes below the starting point of the internal bypass pipe, and there is a gap between the bypass and the bypass valve, the high flow below the bypass valve will generate suction above the bypass valve. Therefore, the mass flow caused by leakage due to the gap is almost completely drawn away again, so no mass flow flows to the pyrolysis reactor.

[0035] A particular advantage here is the small overall structure of the system and the small space required in the vehicle. The system also features simpler insulation and less heat loss due to the elimination of the need for an integral pipework with corresponding surfaces facing the cooling environment. Another advantage is faster heating of the pyrolysis reactor because the supplied bypass mass flow is not cooled by the surrounding environment.

[0036] This invention applies to all diesel engines, particularly commercial vehicles, passenger vehicles, combined heat and power plants, generators, and emergency generator sets, and this list is not exhaustive. This invention is particularly advantageous for all diesel engines with very low exhaust gas temperatures, caused by cold starts, very short running times (e.g., "Stop & Go"), high idling ratios, use only within low load ranges, or use in situations where engine efficiency is good but exhaust gas temperature is correspondingly low.

[0037] Preferably, a bypass is introduced into the intake chamber (Eintrittskammer), downstream of which are connected two pyrolysis reactors, which are preferably arranged symmetrically with respect to the exhaust gas duct.

[0038] The pyrolysis reactors on both sides are "pulled apart," so instead of being placed on the main exhaust pipe as in existing technologies, they can partially cover the main exhaust pipe. This frees up structural space above the main exhaust pipe, significantly reducing the overall system's structural space. The supply of bypass mass flow to the pyrolysis reactors takes place inside the main exhaust pipe, which has an internally "airtight" separation. By pulling apart the inlet chamber, an internal structural space is now formed within it. A pipe is integrated downstream of the throttling valve in the main exhaust pipe, through which the bypass mass flow is supplied to the pyrolysis reactors. This eliminates the need for the entire external piping system, as well as the inlet / exhaust cones and flanges. For example, this internal piping can be achieved by inserting and welding plates. Alternatively, the piping can be achieved by a suitably shaped tube that is simply bonded to the main exhaust pipe.

[0039] Here, the fuel-exhaust gas mixture is formed in the inlet chamber before entering the pyrolysis reactor.

[0040] Preferably, the bypass leads to an exhaust gas heating device having at least one pyrolysis reactor, wherein the exhaust gas heating device has at least one heating source by means of which the nonwoven fabric can be heated, and the fuel introduced into the nonwoven fabric can be at least partially evaporated and / or heated to a temperature above the fuel ignition temperature, and / or the exhaust gas introduced into the intake chamber can be heated to a temperature above the fuel evaporation temperature and / or ignition temperature by means of the heating source, and in particular, at least one flame ignition plug can be arranged upstream of the pyrolysis reactor along the flow direction of the exhaust gas.

[0041] In this regard, it is particularly advantageous that ceramic catalysts can be used as pyrolysis reactors. For example, ceramic catalysts can be fixed by means of expansion pads (Blähmatte) and / or wire mesh (Drahtgestrick).

[0042] Preferably, the bypass is introduced into an exhaust gas heating device having at least one pyrolysis reactor, wherein each pyrolysis reactor has a baffle with multiple through holes downstream of the inlet chamber, through which the fuel-exhaust gas mixture is introduced into the pyrolysis reactor in a uniformly distributed manner.

[0043] Preferably, the bypass is connected to a waste gas heating device having at least one pyrolysis reactor, wherein the waste gas heating device has two metering pumps for metering fuel, wherein fuel is delivered to and metered to the nonwoven fabric by means of a first metering pump, and wherein fuel is delivered to and metered to the flame ignition plug by means of a second metering pump.

[0044] In an operation with an air ratio of Lambda >> 1 (referred to as heated operation), fuel is evaporated before the orifice and then supplied to the pyrolysis reactor along with the exhaust gas through the orifice. This ensures that, in the Lambda >> 1 mode, the distribution of fuel and exhaust gas is completely uniform within the pyrolysis reactor region or within the region where exhaust gas is supplied to the pyrolysis reactor. This ensures that there is never excess fuel locally within the pyrolysis reactor, and therefore the heat generated by oxidation corresponds to the "cooling power" of the mass of exhaust gas supplied locally through the orifice. Consequently, the local temperature within the pyrolysis reactor is almost uniform.

[0045] Fuel evaporates in the inlet chamber of the pyrolysis reactor. To provide sufficient heat for fuel evaporation, a flame igniter is placed in the inlet chamber or in a bypass duct preceding the inlet chamber. Heating power up to, for example, 10 kW can be achieved using the flame igniter. While a small power range up to 10 kW can be provided using only the flame igniter, for higher power applications, fuel is additionally supplied to a nonwoven fabric in the inlet chamber, where it evaporates, mixes with the exhaust gas flowing into the inlet chamber, and is conveyed through orifices to the pyrolysis reactor, where the fuel vapor is oxidized. A uniform lambda can be provided across all orifices using appropriate fluid technology in the inlet chamber. Here, the amount of gas mixture flowing through a particular orifice is irrelevant; the oxidation-to-cooling ratio is constant, therefore the temperature of that local pyrolysis reactor is equal to the temperature at all other locations within the pyrolysis reactor (where exhaust gas is supplied). To reduce the area without pores in the pyrolysis reactor and thus achieve more uniform thermal stress, the diameter of the pores can now be designed to be even smaller, increasing the number of pores and thereby improving the uniformity of heat input and temperature distribution within the pyrolysis reactor. Smaller pores result in a greater pressure drop and a higher flow velocity through the pyrolysis reactor. This facilitates recirculation within the pyrolysis reactor and improves its oxidation performance.

[0046] To prevent coking, or to reduce coking in the intake chamber, nonwoven fabric, and orifices, the Lambda of the flame igniter when operating alone cannot be too lean in order to provide sufficient heat and high temperature through the flame igniter.

[0047] In an operation where the air ratio Lambda << 1 (referred to as DOC operation), fuel is supplied to the nonwoven fabric. In DOC operation, there is no risk of damage due to uneven evaporation distribution. Here, the flame igniter only needs to provide a small power output of less than 2 kW.

[0048] This startup process is particularly advantageous because, compared to systems known according to existing technology, the nonwoven fabric in the intake chamber can be heated more quickly and safely using a flame igniter. Since the bypass mass flow is not cooled by the surrounding environment, the desired temperature level can also be reached more rapidly.

[0049] Furthermore, a particularly advantageous aspect during startup is that the flame ignition plug heats not only the nonwoven fabric but also both pyrolysis reactors. Therefore, simple ceramic catalysts and fixing devices with expansion pads or wire mesh can be used.

[0050] Another advantage of the start-up process and operation is that no radiant heat from the pyrolysis reactor is required. Therefore, the chemical start-up process (i.e., the supply of fuel to the nonwoven fabric and its evaporation and transfer to the pyrolysis reactor) can begin at a pyrolysis reactor temperature of about 270°C, since the fuel vapor can be sufficiently oxidized from this temperature.

[0051] Since the non-woven fabric is positioned within the air inlet chamber, a flame igniter plug can be used to provide high temperatures here. To further eliminate any potential coking, the following steps can be performed:

[0052] - No more fuel is added to this new nonwoven fabric, meaning the fuel itself will not cool down, and the nonwoven fabric will not cool down due to evaporation;

[0053] - In addition, in order to reduce the cooling of nonwoven fabrics, the mass flow of exhaust gas through the pyrolysis reactor can be greatly reduced;

[0054] - By operating the flame ignition plug alone, the lambda range is set to provide a sufficiently high temperature while still remaining within the lean range so that coking can also be oxidized. This mode is required to heat the pyrolysis reactor every time the system is started up;

[0055] - When the engine is off, the inside of the pyrolysis reactor is still very hot, and the heat dissipates, so the non-woven fabric in the intake chamber also becomes very hot.

[0056] During the running cycle, a sufficient time interval can be created during which coking that may exist on the nonwoven fabric, on the inside of the Lochplatte in the air inlet chamber, and in the orifices themselves can be reduced.

[0057] Due to the uniform and localized distribution (equal Lambda) of fuel and oxygen-containing exhaust gas in the intake chamber, the exhaust gas heats up due to oxidation after each feed port. This ensures that there is no localized excessive fuel quantity or localized excessively high temperature that could damage the pyrolysis reactor.

[0058] Since the pyrolysis reactor now uniformly obtains an oxidizable mixture after the orifice, there is no local cooling in the pyrolysis reactor, and any HC or CO that may be generated can be completely oxidized at any local location in the pyrolysis reactor because the pyrolysis reactor is hot everywhere.

[0059] Localized or regional evaporation of fuel on the nonwoven fabric does not affect the uniform distribution of oxidation in the pyrolysis reactor.

[0060] Since the droplets ejected from the nonwoven fabric do not reach the surface of the pyrolysis reactor, but instead evaporate in the inlet chamber first and then flow into the pyrolysis reactor as a mixture, there are no longer any droplets that could be ejected from the nonwoven fabric toward the pyrolysis reactor due to the flow velocity of the exhaust gas discharged from the holes.

[0061] Because of the selected location of the nonwoven fabric in the air intake chamber, it receives almost no cooling through the outer wall, and the flame igniter plug can provide sufficient heat / temperature to decompose any coking that may occur.

[0062] Preferably, the pyrolysis reactor operation (whether heating or DOC operation) utilizes two metering pumps. One metering pump is used for the flame ignition plug, while the second metering pump is used for the nonwoven fabric. Both "distribute the dose" into the inlet chamber, ensuring a uniform distribution between the left and right pyrolysis reactors solely through the inlet chamber. Therefore, two separate temperature sensors are no longer required for the left / right pyrolysis reactors.

[0063] In the "Lambda>>1" operation, the outlet temperature of this new type of pyrolysis reactor is higher than that of a non-uniformly distributed fuel / exhaust gas mixture due to its good uniform distribution. This is because the air ratio can be pushed more towards the direction of Lambda=1 without worrying about local overheating.

[0064] Under heating operation, the pyrolysis reactor has a higher heating power because the temperature is more uniform. Localized excessively high temperatures reduce the overall power. If there are no localized hot spots, the entire pyrolysis reactor can operate hotter, meaning a higher total power. Therefore, more heat of oxidation can be allowed while maintaining the same maximum temperature within the pyrolysis reactor. A larger temperature difference can also exist within the pyrolysis reactor.

[0065] Preferably, at least one catalyst (so-called SCR catalyst) for the selective catalytic reduction of nitrogen oxides is arranged downstream of the exhaust gas heating device. Furthermore, at least one oxidation catalyst may be arranged downstream of the exhaust gas heating device. Attached Figure Description

[0066] Embodiments of the present invention are shown in the accompanying drawings and will be described below. In the drawings:

[0067] Figure 1 A perspective view of the exhaust gas duct is shown;

[0068] Figure 2 It shows that according to Figure 1 Side view of the exhaust gas duct;

[0069] Figure 3 It shows that according to Figure 1 A cross-section of the side view of the exhaust gas duct;

[0070] Figure 4 It shows that according to Figure 3 Section AA;

[0071] Figure 5 It shows that according to Figure 4 BB (section of the cross section);

[0072] Figures 6 to 10 The cross-sections of the throttling valve and bypass valve regions are shown in side and perspective views at different angular positions of the throttling valve.

[0073] Figure 1 A perspective view of the entire system is shown, including an exhaust duct 1 for guiding exhaust gas from an internal combustion engine (not shown) and an exhaust gas heating device 2. An adjustable throttle valve 3 is arranged at the inlet of the exhaust duct 1, which can be driven by a servo motor 4 to achieve the desired setting.

[0074] Figure 2 A side view of the entire system is shown, and Figure 3 A cross-section of the side view of the entire system is shown, which includes an exhaust pipe 1 for guiding the exhaust gas of an internal combustion engine (not shown), an exhaust gas heating device 2, and a servo motor 4 for driving and regulating a throttle valve 3.

[0075] According to Figure 2 and Figure 3 In the diagram, exhaust gas from an internal combustion engine (not shown) flows from left to right through exhaust pipe 1 in the plan view. The exhaust pipe is divided into a main flow pipe 11 and a bypass 12. The flow rate through the main flow pipe 11 and the bypass 12 is regulated by a throttle valve 3; the function of the throttle valve 3 is based on… Figures 6 to 10 To elaborate.

[0076] Bypass 12 leads to exhaust gas heating device 2. The structure and function of exhaust gas heating device 2 are described below based on... Figure 4 and Figure 5 To elaborate.

[0077] Figure 4 It shows that according to Figure 3 The cross section AA of the exhaust gas heating device 2. Figure 4 The image shows only the left half of the exhaust gas heating device 2, which is symmetrical about the centerline 13 of the exhaust gas duct 1. As described, the exhaust gas duct 1 is divided into a main flow duct 11 and a bypass 12. The bypass 12 enters the intake chamber 21 of the exhaust gas heating device 2 via the exhaust gas inlet 14. Fuel 23 is supplied to the intake chamber 21 by means of a metering pump (not shown) through a nonwoven fabric 22.

[0078] As described, the exhaust gas heating device 2 is mirror-symmetrical about the centerline 13 of the exhaust gas duct 1 and is mounted on the exhaust gas duct 1 in a manner similar to that of an earphone. Figure 1 As can be seen from the perspective view, the arrangement of the exhaust gas heating device 2 on the exhaust gas duct 1 is very space-saving.

[0079] Fuel 23 evaporates and mixes with exhaust gas in inlet chamber 21, and the mixture then flows through orifice 24 of orifice plate 25 to pyrolysis reactor 26. For orifice plate 25, a mixer, guide plate, or sieve may be used, additionally or alternatively, to achieve uniform distribution. Here, the heat required for evaporation is provided by a flame ignition plug (not shown). At these high temperatures, coking that may occur in orifice 24 or on nonwoven fabric 22 can be reduced by decreasing the mass flow of exhaust gas through device 2 and shutting off the diesel fuel supply to the nonwoven fabric 22. As described above, in pyrolysis reactor 26, the fuel-exhaust gas mixture is further heated, and then further guided through surface 27 to outlet 28 and reintroduced into the main flow duct 11 of exhaust gas duct 1. The separation between inlet chamber 21 and outlet 28 is achieved by means of partition wall 29.

[0080] The orifice plate or baffle 25 is used to direct the exhaust gas mass flow toward the pyrolysis reactor 26 and to form a uniform velocity distribution on the cross-section of the pyrolysis reactor 26.

[0081] Since the fuel introduced into the pyrolysis reactor 26 is pre-evaporated, the fuel and the oxygen component in the exhaust gas mass flow introduced into the pyrolysis reactor 26 begin to oxidize, thereby automatically heating the device 2 further.

[0082] exist Figure 5 The text shows the data based on... Figure 4 The cross-section BB shows the perforated plate 25 with holes 24, through which the fuel-exhaust gas mixture formed in the inlet chamber 21 is introduced into the pyrolysis reactor 26. Figure 5 (Not visible in the image). It can be seen that the supplied fuel-exhaust gas mixture is uniformly distributed in the exhaust gas heating device 2 through the orifice 24 of the exhaust gas supply device. Oxygen-rich exhaust gas (including pre-evaporated fuel) is supplied in a uniformly distributed manner on the marked area 25' of the orifice plate 25. The heated fuel-exhaust gas mixture is returned to the exhaust gas duct 1 via the outlet 28.

[0083] Regardless of whether the fuel metering is low or high, i.e., whether the heating power required by the exhaust gas heating device 2 is low or high during the heating operation, the fuel 23 evaporates within the inlet chamber 21 (i.e., the exhaust gas supply device). The distribution and mixing of the fuel vapor occur within the inlet chamber 21, ensuring a uniform supply of fuel and exhaust gas mass flow through the orifice 24. Therefore, the air ratio is uniform within region 25', where uniform and complete oxidation occurs. Consequently, areas with excessively high temperatures are excluded. Thus, the temperature of the pyrolysis reactor 26 can now be precisely regulated.

[0084] Locally excessive oxygen cannot enter the oxidation process because the locally available fuel will not exceed the fuel uniformly distributed across orifices 24. Regardless of the amount of mixture flowing through orifices 24, the temperature generated in pyrolysis reactor 26 remains constant. Therefore, pyrolysis reactor 26 will not experience localized overheating at any point. Instead, the temperature can be adjusted to well below the durability temperature of pyrolysis reactor 26. This significantly improves the stability of the system.

[0085] exist Figures 6 to 10 The cross-sections of the regions of the throttling valve 3 and the bypass valve 31 are shown in side and perspective views at different angular positions of the throttling valve 3. The flow rates through the main flow pipe 11 and the bypass 12 are regulated by means of the throttling valve 3 and the bypass valve 31; the functions of the throttling valve 3 and the bypass valve 31 will be described below. The throttling valve 3 is regulated by means of a servo motor 4, which rotates the throttling valve 3 about the rotation axis 32.

[0086] from Figures 6 to 10 As shown in the diagram, the throttle valve 3 can rotate around the axis 32 by means of the servo motor 4, according to... Figure 6 The opening position and according to Figure 10 The main flow channel 11 is pivoted in the closed position. In the open position, the main flow channel 11 is released, and in the closed position, the main flow channel 11 is blocked.

[0087] The bypass valve 31 is kinematically connected to the throttling valve 3, such that when the bypass 12 is closed, the throttling valve 3 is in its proper position. Figure 6 When the bypass 12 is fully released, the throttle valve 3 is in its open position, and when the bypass 12 is fully released, the throttle valve 3 is in its position according to... Figure 10 The closing position. According to Figure 10 At this position, the main flow duct 11 is blocked and the bypass 12 is fully open. Therefore, at this position of the throttling valve 3 and the bypass valve 31, the exhaust gas mass flow is completely guided through the bypass 12. According to... Figure 6 At this position, the main flow duct 11 is open and the bypass 12 is closed by means of the bypass valve 31. Therefore, at this position of the throttling valve 3 and the bypass valve 31, the exhaust gas mass flow is completely guided through the main flow duct 11.

[0088] The next Figures 7 to 9 The intermediate positions of the throttling valve 3 and the bypass valve 31 are shown, by means of which the required distribution of the exhaust gas mass flow between the main flow duct 11 and the bypass 12 can be continuously adjusted.

[0089] The throttling valve 3 and the bypass valve 31 are implemented as a single unit, and therefore consist of a single component. The throttling valve 3 and the bypass valve 31 can pivot synchronously about a common rotation axis 32 in a manner that is not rotatable relative to each other. As explained above, the throttling valve 3 and the bypass valve 31 pivot by means of a servo motor 4.

Claims

1. An exhaust gas duct (1) for guiding exhaust gas from an internal combustion engine, wherein, The exhaust gas duct (1) has at least a main flow duct (11) and a bypass (12), and an adjustable throttling valve (3) in the main flow duct (11), wherein the throttling valve (3) is pivotable from an open position to a closed position, wherein the main flow duct (11) is open in the open position and closed in the closed position, wherein a bypass valve (31) is kinematically connected to the throttling valve (3) such that the throttling valve (3) is in its open position when the bypass (12) is closed, and the throttling valve (3) is in its closed position when the bypass (12) is fully open. Its features are, The bypass (12) is formed as an integral part of the main flow pipe (11), wherein the bypass (12) leads to a device (2) for heating exhaust gas having at least one pyrolysis reactor (26), at least a portion of the mass flow of exhaust gas from the internal combustion engine is introduced into the pyrolysis reactor via the bypass (12), wherein at least one nonwoven fabric (22) is connected upstream of the pyrolysis reactor (26), the nonwoven fabric being fueled, wherein the fuel evaporates and undergoes an exothermic reaction in the pyrolysis reactor (26) with the oxygen component of the exhaust gas mass flow introduced into the pyrolysis reactor (26) through oxidation, wherein the exhaust gas heated by means of the device (2) is introduced into the main flow pipe (11) downstream of the device (2) for heating exhaust gas. The throttling valve (3) and the bypass valve (31) are formed by a single component, wherein the throttling valve (3) and the bypass valve (31) are capable of pivoting synchronously about a common axis of rotation (32) in a manner that is not rotatable relative to each other.

2. The exhaust gas pipeline (1) according to claim 1, characterized in that, The throttling valve (3) and the bypass valve (31) are formed from castings or injection molded parts of the same material.

3. The exhaust gas pipeline (1) according to claim 1, characterized in that, The fuel evaporates and undergoes an exothermic reaction in the pyrolysis reactor (26) with the oxygen component of the exhaust gas mass stream introduced into the pyrolysis reactor (26) through oxidation, thereby providing a sufficiently high pyrolysis temperature.

4. The exhaust gas pipe (1) according to any one of claims 1-3, characterized in that, A servo motor (4) is provided, by means of which the throttle valve (3) and the bypass valve (31) are pivoted.

5. The exhaust gas pipeline (1) according to any one of claims 1-3, characterized in that, The bypass (12) is formed by the flow pipe of the sub-sector that forms the exhaust pipe (1) in cross-section.

6. The exhaust gas pipeline (1) according to any one of claims 1-3, characterized in that, The bypass (12) is formed by the circular portion of the exhaust gas pipe (1) with a circular cross-section.

7. The exhaust gas pipe (1) according to any one of claims 1-3, characterized in that, The bypass (12) leads into the intake chamber (21), which is connected downstream of two pyrolysis reactors (26).

8. The waste gas pipeline (1) according to claim 7, characterized in that, The two pyrolysis reactors are arranged symmetrically with respect to the exhaust gas duct (1).

9. The exhaust gas pipeline (1) according to any one of claims 1-3, characterized in that, The bypass (12) leads to a device (2) for heating exhaust gas having at least one pyrolysis reactor (26), wherein the device (2) for heating exhaust gas has at least one heating source by means of which the nonwoven fabric (22) can be heated, and the fuel introduced into the nonwoven fabric (22) can be at least partially evaporated and / or heated to a temperature higher than the ignition temperature of the fuel, and / or the exhaust gas introduced into the intake chamber (21) can be heated to a temperature higher than the evaporation temperature and / or ignition temperature of the fuel by means of the heating source.

10. The exhaust gas pipeline (1) according to claim 9, characterized in that, It is equipped with a flame ignition plug.

11. The exhaust gas pipe (1) according to any one of claims 1-3, characterized in that, The bypass (12) leads to a device (2) for heating exhaust gas with at least one pyrolysis reactor (26), wherein each pyrolysis reactor (26) has a baffle (25) with multiple through holes (24) downstream of the inlet chamber (21), through which the fuel-exhaust gas mixture is introduced into the pyrolysis reactor (26) in a uniformly distributed manner.

12. The exhaust gas pipe (1) according to any one of claims 1-3, characterized in that, The bypass (12) is connected to a device (2) for heating exhaust gas having at least one pyrolysis reactor (26), wherein the device (2) for heating exhaust gas has two metering pumps for metering fuel, wherein fuel is delivered to and metered to the nonwoven fabric (22) by means of a first metering pump, and wherein fuel is delivered to and metered to the flame ignition plug by means of a second metering pump.

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