Production of aging gas for exhaust aftertreatment systems

Abstract

Method for generating aging gas for aging components for exhaust aftertreatment in a burner (10) which has a combustion chamber (11) with at least one fuel injection nozzle (31) and with a combustion air supply with means for generating swirl (62), wherein the swirl of the combustion air is adjusted depending on the selected combustion air ratio λ, characterized in that, to simulate a vehicle overrun shutdown after an interruption of the fuel supply for restarting the combustion chamber (11), a combustion air ratio λ < 1 (rich) and a high swirl of a primary air flow are set.

Description

Field of invention

[0001] The invention relates to a method and a device for generating aging gas for the aging of exhaust aftertreatment components such as catalytic converters and particulate filters, as well as a method and a device for artificially aging exhaust aftertreatment components such as catalytic converters and particulate filters by exposing them to aging gas generated in a burner. Motor vehicles with internal combustion engines are regulated by emission laws, which can currently only be met by exhaust aftertreatment systems installed downstream of the combustion engine in the exhaust system.

[0002] These exhaust aftertreatment systems must meet legally mandated durability standards. For the European Union, this means a minimum service life of 100,000 km after the introduction of the EURO 4 emissions standard, while after the introduction of the EURO 5 standard, a service life of 160,000 km is required. For homologation (type approval) of a vehicle, the long-term durability of the corresponding exhaust aftertreatment systems must be demonstrated. For this purpose, artificial aging procedures are permitted, which simulate the wear and damage processes that occur during the vehicle's operating life through testing on a test bench.

[0003] To monitor the durability of exhaust aftertreatment systems during vehicle operation, on-board diagnostic (OBD) systems are required. These systems alert the driver to malfunctions in the exhaust aftertreatment systems if emission limits are exceeded. The effectiveness of these on-board diagnostic systems is also tested during type approval using artificially aged exhaust aftertreatment systems. Aging

[0004] Catalytic converter aging refers to the decreasing efficiency of exhaust aftertreatment due to operation, primarily caused by the degradation of the catalytically active layer. As the active surface area decreases, not all emissions can be oxidized or reduced, leading to an increase in emissions released into the environment downstream of the catalyst. Two main mechanisms are responsible for catalyst aging, and these can occur together or separately depending on the operating point. Both mechanisms are also used for targeted catalyst aging. Thermal aging

[0005] Catalytic converters are designed to operate at temperatures between 200 and 950°C. Within this temperature range, aging progresses very slowly. If the operating temperature rises above 850°C, aging accelerates, a process known as thermal aging. This increases rapidly when temperatures exceed 1000°C. During this process, the active surface area is reduced through sintering. At temperatures of 1400°C and above, the ceramic core melts, leading to its complete destruction. This typically manifests as a loss of engine power due to excessive exhaust backpressure within the catalytic converter. poisoning

[0006] Catalyst poisoning can occur in two ways. Firstly, chemical poisoning of the active surface can occur due to foreign substances such as fuel or oil additives, which partially destroy and thus reduce the catalytic layer through chemical reactions. Secondly, mechanical poisoning occurs. In this case, the active layer is covered by substances such as lead and sulfur from fuel and oil, which in turn leads to its reduction. OSC measurement (Oxigenic Storage Capacity)

[0007] To determine the aging status of a catalytic converter, an OSC measurement is performed. This measurement serves to determine the oxygen storage capacity of the catalyst, from which its aging state can then be derived. The older the catalyst, the lower its storage capacity. OSC measurement is used both in production vehicles and in artificial catalyst aging.

[0008] OSC measurement is performed under steady-state conditions of exhaust gas temperature and mass flow. For this purpose, the lambda signals are measured before and after the catalytic converter. The engine or burner is operated in such a way that the exhaust gas transitions rapidly from a rich mixture (lambda <1) to a lean mixture (lambda >1). The phase shift between the pre- and post-catalytic converter signals (after the lambda transition) is proportional to the oxygen stored in the catalytic converter. Artificial aging

[0009] Through artificial aging using aging gas generated in a burner, long-life and limit catalysts can be produced. For long-life catalysts, aging cycles are used that produce comparable aging results to catalysts aged in road traffic. Measurements are taken at defined intervals to determine the catalyst damage of the catalyst under test. This information is then used by automotive manufacturers to develop vehicle-specific catalysts with regard to their design, coating, and service life. Once the optimal configuration has been achieved, the catalyst can be used. Additional dynamic cycles, such as the standard test cycle prescribed by law or the ZDAKW cycle, can also be performed, in which air and / or fuel can be dynamically metered upstream of the catalyst to simulate an exothermic reaction.

[0010] In contrast, limit catalysts are aged until they reach the regionally legally defined OBD emission limits. This limit is then used to create a control model for the vehicle that can detect when these emission limits are exceeded. As in the vehicle itself, the so-called OSC measurement is available on the burner test bench to measure the degree of aging of the catalysts. OBD Catalyst Age Limit (On-Board Diagnostics)

[0011] During OBD limit catalyst testing, the catalysts are aged at a constant operating point for a specific period. Thermal aging is used for this process. The goal of this aging method is to age the catalyst to the point where it just barely meets the OBD emission limits. Since each vehicle-specific catalyst behaves differently depending on its coating, the duration of the aging process is unpredictable. Therefore, the aging process is divided into intervals followed by OSC measurements to prevent the catalyst from exceeding the limit and becoming unusable due to excessive aging time. In parallel with the OSC measurements, an exhaust gas test is also performed to determine the emissions of the aged catalyst.For this purpose, the catalyst is installed from the test bench into the corresponding vehicle and the measurement is carried out on a roller test bench in a realistic environment (real engine with exhaust aftertreatment system).

[0012] Since oxygen storage capacity and emissions are inversely proportional, but determining emissions in a production vehicle is complex, the OSC value serves as a measure of emissions. During OBD catalyst aging testing, the OSC value at which the vehicle's emissions are borderline is determined. Later, in a production vehicle, an OSC measurement can then detect a defective catalyst and a failure to meet emission limits. ZDAKW Aging (Collaboration of the German automotive industry for catalyst development)

[0013] The ZDAKW cycle was developed by the Exhaust Gas Center of the German Automotive Industry (ADA). It was designed to provide a standardized test procedure for catalytic converter coatings. This cycle essentially consists of a high-temperature phase with five overrun fuel cut-offs and a poisoning phase with three temperature levels. During overrun fuel cut-off, fuel injection is briefly interrupted and the exhaust gas mass flow is simultaneously reduced. This purges the catalytic converter with oxygen and establishes a lambda value of approximately 8. When the mass flow is subsequently increased and injection resumes, the lambda value rises again to the regulated value of 1. This process is intended to simulate driving during sudden acceleration and deceleration. In the poisoning phase, a slightly richer exhaust gas mixture is passed through the catalytic converter at lower temperature levels.This results in a reduction of the catalytically active layer due to chemical poisoning. State of the art

[0014] Simulating the aging of exhaust aftertreatment systems, especially exhaust catalysts, on engine test benches is possible, but is expensive on the one hand and difficult to reproduce on the other, since engine aging influences represent an incalculable factor.

[0015] Based on this, methods and devices have been developed for generating aging gas for exhaust aftertreatment systems in burners. These burners burn either gasoline or diesel fuel in specific simulation cycles designed to mimic exhaust gas generation during vehicle operation. The corresponding operating cycles of the burners used must be capable of simulating malfunctions such as misfires and overrun fuel cut-off.

[0016] US Patent 7,140,874 B2 discloses a method and a device for testing exhaust catalysts, in which a burner is used that has a swirl plate upstream of the combustion chamber. This swirl plate has a central through-hole into which a fuel injector nozzle injects fuel, and circumferentially distributed bores through which the combustion air flows into the combustion chamber. These circumferentially distributed bores have, at least partially, a profile with tangential and radial components from the inlet side to the outlet side, which results in a swirl of the combustion air at the inlet to the combustion chamber.

[0017] The production of these swirl plates is costly, and optimized combustion is only possible at a single burner operating point. In contrast, the aging cycles necessitate different operating conditions, as the aging gas must be supplied at varying temperatures and, if necessary, generated with different combustion air ratios. This is particularly relevant when considering the use of gasoline and diesel fuel in the same burner.

[0018] WO 2006 / 138174 A2 discloses a method for generating a flame from the exhaust gas of a Wankel or reciprocating engine, wherein no additional combustion air is supplied and the generated flame is stabilized by applying a swirl. The heated exhaust gas is directed into an emission reduction device.

[0019] WO 2004 / 007922 A1 describes a process for the artificial aging of a catalyst used on a catalyst test bench, wherein the catalyst serves to convert C-, HC- and NOx-containing components and wherein, within the process, the catalyst is supplied with aging gas comprising the aforementioned components.

[0020] DE 25 39 993 A1 teaches a burner with an outer tube, an inner tube located therein and a fuel injector arranged in the inner tube, wherein gas flows can be generated both within the inner tube and the outer tube and wherein means for swirl generation and volume flow control are further provided in the burner.

[0021] EP 1 580 486 A1 teaches a burner for burning fuel, wherein the burner has a primary nozzle for supplying fuel and a primary airflow, a secondary nozzle for supplying a secondary airflow and a tertiary nozzle for supplying a tertiary flow, wherein the burner includes a partition between the secondary and tertiary nozzles and wherein the partition is movable such that the tertiary flow is redirected from an axial flow direction into a direction that leads to the discharge of the flow from the burner.

[0022] DE 197 38 054 A1 discloses a method and a device for changing the swirl number of the combustion air of a burner such that advantageous recirculation of combustion gases within the burner is achieved. This is to be accomplished by changing the ratio of an angular momentum flow to an axial momentum flow within the burner and thus a recirculation flow through recirculation openings distributed circumferentially on a flame tube.

[0023] US Patent 2003 / 0079520 A1 describes a device for testing the performance of a vehicle catalyst, wherein the device includes a burner and is intended to simulate long-term operation of the catalyst, wherein the device includes a swirl plate and a fuel injector, which are intended to ensure long-term operation of the burner under stoichiometric conditions.

[0024] US Patent 5,257,927 A discloses a burner which has an annular jacket arranged in an outer casing, such that a primary airflow and an external secondary airflow can be generated within the burner, the burner further comprising means for swirl generation and volume control. The means for swirl generation are swirl blades distributed circumferentially around a burner axis and pivotable.

[0025] DE 10 2005 037 639 A1 discloses a device for regenerating a particulate filter, wherein the device comprises a burner, a fuel injector for supplying the burner with fuel and an ignition device, wherein the injection of the fuel into the burner is to be pulsed and carried out at high pressure. Task

[0026] Based on this, the invention aims to provide a method and a device that can provide aging gases of different temperatures in stable burner operation, and with which aging gas with different combustion air conditions can also be produced in stable burner operation. Production of aging gas

[0027] The solution consists of a method for generating aging gas for the aging of exhaust aftertreatment components, in particular exhaust catalysts, in a burner which has a combustion chamber with at least one fuel injection nozzle and with a combustion air supply with means for generating swirl, wherein the swirl of the combustion air is adjusted depending on the selected combustion air ratio λ, wherein a fuel cut-off of an internal combustion engine can be simulated by interrupting the fuel supply to the burner and setting a combustion air ratio λ < 1 (rich fuel mixture) in combination with a very high swirl of the primary air flow to restart the combustion chamber.This makes it possible to ensure stable operation for various combustion air conditions and different process parameters by precisely presetting the swirl of the combustion air, whether depending on the fuel used (gasoline, diesel) or on the desired exhaust gas temperature and / or composition. Furthermore, this results in good ignition properties, allowing for very controlled adherence to the shutdown phases. Exhaust gas can also be routed through the catalyst in a bypass to reduce the mass flow. Suitable exhaust flaps can be used to control the mass flows. Multiple catalysts can also be aged in parallel, and the mass flows regulated by appropriate exhaust flaps. Additionally, when constructing exhaust manifolds, the temperature of the individual partial mass flows can be adjusted by metered exhaust gas recirculation and / or individual exhaust flaps.

[0028] The aging gas is generated by burning a carbon-containing fuel with combustion air in the burner. The composition of the aging gas can be modified by adding auxiliary gas and / or other substances, particularly oil, to closely resemble natural engine exhaust gases. Auxiliary gases can be added in pure form from storage tanks, i.e., gas cylinders. The aging gas should have a temperature of > 250°C, preferably > 700°C, and particularly between 1000 and 1250°C, but optionally also a temperature of < 200°C.

[0029] The air-fuel ratio can be varied in predetermined cycles according to the test procedure. In this way, the exhaust aftertreatment system undergoing aging can be subjected to different aging gas compositions and temperatures, corresponding to a load spectrum similar to that encountered during mixed vehicle operation. By adjusting the air-fuel ratio as well as the fuel and air quantities, the exhaust aftertreatment system can be subjected to cyclic thermal loads and thus experiences conditions similar to those encountered during real-world driving.

[0030] A typical aging cycle lies within a temperature range of 800 to 1250°C. Special aging cycles can also be simulated, in which the start-up behavior of the exhaust aftertreatment system is replicated on the test bench.

[0031] Particularly effective safeguarding of stable burner operation, even with dynamic changes in operating conditions, is possible by changing the swirl of the combustion air depending on changes in the combustion air ratio λ during the generation of aging gases.

[0032] It is particularly useful if the swirl of the combustion air is set lower at a combustion air ratio λ > 1 (lean / stoichiometric) than at a combustion air ratio λ < 1 (rich combustion air ratio).

[0033] The flow of combustion air (fresh air) supplied to the burner must be mass flow controllable, in particular by means of an external combustion air supply system.

[0034] It has proven particularly advantageous to supply combustion air with swirling elements in an internal primary airflow of the combustion chamber and essentially without swirling elements in an external secondary airflow. This is especially true when at least one fuel injector is centrally located in the combustion chamber. An ignition device is to be positioned some distance behind the fuel injector in the combustion chamber.

[0035] Furthermore, it is advantageous to vary the amount of combustion air supplied in response to a change in the fuel injection quantity, without causing excessive effects on the swirl. For this purpose, the external secondary airflow is designed to be throttleable.

[0036] Fuel injection into the combustion chamber should be controllable by pulses at high pressure of more than 20 bar.

[0037] In a favorable embodiment, the aging gas is mixed with the combustion air via an internal recirculation within the burner, near at least one fuel injector. This requires creating a Venturi effect in the central combustion airflow, through which the recirculated aging gas can be drawn in near the fuel injector. This method is called primary exhaust gas or aging gas recirculation.

[0038] To avoid any adverse effect on the aging gas temperature, the primary aging gas recirculation is also reduced when the secondary airflow is throttled.

[0039] To ensure stable, uniform combustion processes in the combustion chamber, the axial position of the burner flame is detected according to a preferred method, for example based on the maximum temperature, and the swirl of the combustion air is increased when the burner flame migrates backwards and reduced when the burner flame migrates forwards.

[0040] In a simulation of the exhaust gas recirculation occurring in engine operation, with which improved exhaust gas values ​​can be achieved, a further special procedure is provided for in which conditioned aging gas is added to the aging gas originally generated in the burner in the combustion chamber.

[0041] In this process, the recirculated aging gas can be cooled and dried to influence the aging gas temperature that affects the exhaust aftertreatment systems. This method variant is called secondary exhaust gas recirculation or secondary aging gas recirculation.

[0042] The proportion of secondary aging gas recirculation in the burner is varied, particularly depending on the desired aging gas temperature. The aging gas from the secondary aging gas recirculation is preferably added to the burner in the form of an annular flow.

[0043] The conditioned aging gas can be taken from an aging gas main line downstream of the exhaust aftertreatment components or from an aging gas bypass line that bypasses these components.

[0044] In a further embodiment, the aging gas generated in the burner is mixed with recirculated aging gas, either cold or hot conditioned, downstream of the burner and before it enters the exhaust aftertreatment components. This also allows for influencing the temperature of the aging gas entering the exhaust aftertreatment system. The process variant described here is referred to as tertiary exhaust gas recirculation or aging gas recirculation.

[0045] Oil, fuel, foreign gas, and / or air can be added to the aging gas from the secondary and / or tertiary exhaust gas recirculation or the exhaust gas upstream of the catalytic converter, as occurs naturally with age-related wear during combustion in an internal combustion engine. The advantage here lies in the reproducibility of these process steps in the production of the aging gas over time, i.e., across the cycles of aging gas production. Methods for aging

[0046] The invention comprises a method for aging exhaust aftertreatment components, in particular exhaust catalysts, by exposing them to aging gas produced according to the aforementioned conditions. The artificial aging of an entire exhaust aftertreatment system is thereby carried out by generating hot aging gas containing C-, HC- and / or NOx-containing components in a burner and passing it through the exhaust aftertreatment system, wherein the hot aging gas stresses the corresponding exhaust aftertreatment components for the aftertreatment of C-, HC- and / or NOx-containing components in a similar manner to naturally produced engine exhaust gas during operation. burner

[0047] The invention further comprises a burner for generating aging gas for the aging of exhaust aftertreatment components, in particular exhaust gas catalysts, comprising a combustion chamber with a combustion chamber axis and at least one fuel injection nozzle and a combustion air supply which has means for generating swirl, wherein the means for generating swirl are adjustable in the sense of changing the swirl strength of the combustion air, wherein a mixing tube arranged concentrically to the combustion chamber axis is located within the burner jacket, which forms an annular space with the burner jacket, to which a feed nozzle for conditioned recirculated aging gas is connected, wherein the mixing tube extends beyond the length of the flame tube and has circumferentially distributed outlet openings for the conditioned aging gas behind the end of the flame tube.Such a burner allows, in particular, the addition of secondary recirculated conditioned aging gas, as previously described in connection with the process flow. The corresponding swirl generation means can be adjusted externally without disassembling the burner, enabling presetting of the swirl or allowing adjustment of the swirl during operation. This adjustment can be made according to pre-programmed combustion cycles and / or within the framework of control processes.

[0048] The means for generating swirl in the combustion air supply are, in particular, circumferentially distributed swirl vanes pivotable on pins about axes arranged radially to the combustion chamber axis. These are preferably engaged with a single rotatable adjusting ring that interacts with all swirl vanes.

[0049] In a preferred embodiment, a ring plate or funnel is provided in the combustion air stream upstream of the fuel injection nozzle, dividing the combustion air stream into an inner primary air stream and an outer secondary air stream, with the means for generating swirl preferably located in the primary air stream. This allows, in particular, the combustion air stream located near the fuel injection nozzle to be provided with a variable swirl, while the outer secondary air stream, which may constitute a larger volume flow fraction, remains essentially swirl-free.

[0050] However, it is still provided that means for controlling the volume flow of the combustion airflow are included, and these can act in particular on the external secondary airflow. For this purpose, the means for controlling the volume flow of the combustion airflow are designed as a ring of adjustable orifice plates arranged concentrically to the fuel injection nozzle.

[0051] To detect the axial position of the burner flame within the combustion chamber, one or more special sensors may be provided, in particular temperature sensors that are distributed along the length of the combustion chamber.

[0052] Further design features include a concentrically arranged flame tube within the combustion chamber, which terminates before the end of the combustion chamber and has circumferentially distributed outlet openings near the fuel injection nozzle for the return flow of primary aging gas. To ensure that this gas is fed back in a self-sustaining return flow, the outlet openings in the flame tube are located in a nozzle-like constricted section of the flame tube downstream of the fuel injection nozzle, thereby creating a Venturi effect in the primary combustion airflow. Aging system

[0053] The invention comprises a system for artificially aging exhaust gas catalysts or exhaust gas aftertreatment systems by exposing them to aging gas generated in a burner, in which a burner according to one of the aforementioned embodiments is used. Components of the plant

[0054] Such a system consists of the components air supply, fuel supply, burner with mixing device, aging section for the exhaust gas aftertreatment components to be aged and aging gas recirculation. Air supply

[0055] The burner is supplied with combustion air via the air supply system to later create an ignitable mixture with the fuel. Fresh air is drawn in through an air filter and compressed by a Roots compressor driven by an asynchronous motor. Due to the pressure differential with the ambient air at the exhaust stack downstream of the exhaust aftertreatment system, a mass flow is generated in this direction. The asynchronous motor's speed is controlled by a frequency converter. The temperature of the compressed combustion air can then be reduced via a counterflow heat exchanger. Downstream of the air filter, a hot-film air mass meter (HFM) measures the mass flow, which is then regulated by a throttle valve. The fast-acting throttle valve is necessary because the Roots compressor is too slow to handle the rapid mass flow changes required for different cycles.This ensures that the combustion air reaches the burner head with a specific mass flow rate and temperature. Fuel supply

[0056] Fuel is pumped from a tank to the burner by a fuel pump. A mass flow meter measures the fuel flow rate. Excess fuel is cooled via a counterflow heat exchanger. A high-pressure pump then pressurizes the fuel to 50 bar, the pressure required for the injection valve. Burner with mixing device

[0057] On the inlet side, an inlet manifold, also called a burner head, forms the transition from the cold to the hot part of the system. On the outlet side, the burner chamber forms the transition to the exhaust gas aftertreatment system via a flange.

[0058] To cool the components in the mixing unit, the double-shell inlet manifold is cooled by a cooling water jacket.

[0059] The mixing device essentially consists of the components air control apparatus with swirl device and orifice, injection nozzle with injection valve and the flame tube.

[0060] The mixing device has the task of mixing the fuel and combustion air in such a way that a combustible mixture is created, which is burned in the flame tube in order to provide an exhaust mixture at the burner outlet that is similar to the exhaust gases of a gasoline or diesel engine.

[0061] After the exhaust gas leaves the combustion chamber, it is gradually cooled by the addition of the cooled, conditioned aging gas from the secondary exhaust gas recirculation (EGR). The lateral feed creates a swirl flow around the mixing tube. Baffles and bores force the cooler recirculated aging gas into the combustion chamber, resulting in progressively lower temperatures towards the rear. The exhaust gas temperature at the burner outlet can be further influenced by the targeted addition of air. The mass flow that subsequently passes through the exhaust aftertreatment system consists of the fresh air mass flow, the EGR mass flow, and the fuel mass flow.

[0062] By measuring the temperature at several points in the combustion chamber, the position of the flame can be detected and the position adjusted by changing the swirl. Aging section

[0063] The aging section extends between two flange connections. The first is located directly behind the burner outlet, while the second is situated before a diesel particulate filter. The flanges are spaced at a constant distance, allowing the catalysts to be pre-adapted to the system. Since the geometry and exhaust gas flow of the catalysts being aged are usually very different, this adaptation must always be carried out individually. Typically, each catalyst is equipped with pre- and post-catalyst connection sleeves for lambda sensors and several screw-in sleeves for thermocouples and temperature sensors. Taking into account the burner's aging gas capacity and the catalysts' aging gas requirements, two or more catalysts can be connected in parallel within the aging section. For mass flow control, at least one bypass line to the catalysts in the aging section can be provided. Aging gas recirculation

[0064] The aging gas recirculation system extracts a portion of the exhaust gas mass flow upstream of the exhaust stack, cools it, and then mixes it back into the original aging gas. To do this, the hot aging gas is passed through a counterflow heat exchanger, which cools it to approximately 40°C. The now-cooled aging gas is then passed through a cyclone separator to filter out the liquid phase after cooling. A hot-film air mass meter (HFM) measures the mass flow rate of the recirculated aging gas, which is then regulated by a throttle valve and a Roots compressor. Finally, the cooled aging gas reaches the burner, where it is mixed with the hot, originally generated aging gas via the mixing tube. Examples of implementation

[0065] Preferred embodiments of a burner according to the invention and of a system according to the invention for the artificial aging of exhaust gas catalysts are shown in the drawings and are described below. Fig. Figure 1 shows a burner according to the invention in overall view in oblique view with partial section; Fig. Figure 2 shows part of the burner with combustion chamber. Fig. 1 in oblique view with partial section; Fig. Figure 3 shows the front area of ​​the burner after the Fig. 1 and Fig. 2 with air supply arc in oblique view with partial section; Fig. Figure 4 shows the mechanical parts for air supply control as well as the beginning of the flame tube after the Fig. 1 to 3 in longitudinal section; Fig. Figure 5 shows a schematic diagram of a system according to the invention for the artificial aging of exhaust gas catalysts; Fig. Figure 6 shows a side view of an implemented example of a system according to the invention for the artificial aging of exhaust gas catalysts. Fig. Figure 7 shows a diagram of an OSC measurement on a catalyst. Fig. Figure 8 shows a diagram of the ZDAKW catalyst aging cycle.

[0066] In Fig. Figure 1 shows a burner 10 according to the invention with a combustion chamber 11, comprising an outer rotationally symmetrical burner jacket 12 extending between an inlet flange 13 and an outlet flange 14 and comprising three longitudinal sections 16, 17, 18 with diameters decreasing from the inlet flange to the outlet flange, each connected to the other via conical transition areas 19, 20. A support flange 15 is screwed onto the inlet flange 13, comprising an outer collar and an inner annular projection, which are described in more detail in the following figures. The collar centers the inlet flange 13, to which the burner jacket 12 is attached. The inner ring attachment on the support flange 15 carries a mixing tube 21 on the outside for recirculated conditioned aging gas and extends at radial distance over the length of the first two sections 16, 17 of the burner jacket 12 as well as the two conical transition areas 19, 20.From transition area 19 to transition area 20 inclusive, the mixing tube 21 has essentially uniformly distributed inlet openings 22.

[0067] The inner ring extension on the support flange 15 carries an internal cylindrical flame tube 23, which extends lengthwise essentially over the first section 16 of the largest diameter of the burner jacket 12. The flame tube 23 has two rows of recirculation openings 24 for primary aging gas recirculation, which will be explained later.

[0068] An aging gas return pipe 26 is connected to the burner jacket 12, which opens into an annular space between the burner jacket 12 and the auxiliary guide pipe 21 shortly after the inlet flange 13. This aging gas return pipe 26 serves for the so-called secondary aging gas return.

[0069] Upstream of the flame tube 23 on the inlet side is a mixing device 25 with a fuel injection nozzle 31 and an air control device 32. The air control device 32 comprises an adjustable swirl device and an adjustable throttle plate for the combustion air, which will be discussed later. Upstream of the burner 10 and connected to it by means of a connecting flange 33 is an air supply manifold 34, which has an inner jacket 35 and an outer jacket 36, between which a chamber 38 for cooling water is formed. In addition to the connecting flange 33, the air supply manifold 34 has an inlet flange, which is not shown here. Further details of the latter parts can be seen from the following figures.

[0070] The combustion principle used corresponds to that of a swirl-stabilized burner. Fresh air flows from the rear out of the cooled air supply manifold 34 into the mixing unit 25. There, the airflow splits into an inner primary and an outer secondary airflow. In the primary airflow, the fresh air flows internally over the swirl device. It is then mixed with the injected fuel in front of a primary air bore in the throttle orifice, and the combustible fuel-air mixture enters the flame tube 23. In the secondary airflow, the fresh air is directed around the swirl device and flows into the flame tube through secondary air bores in the throttle orifice, surrounding the fuel-air mixture to supply oxygen to the outer regions during combustion and to draw back some of the aging gas produced during combustion via the recirculation bores 24 in the flame tube 23.By changing the opening cross-section of the secondary air bores in the throttle orifice, the air volume can be variably controlled by the swirl device (primary air bore) and around it (secondary air bores). This changes the airflow velocity at the outlet of the mixing device 25, creating a negative pressure at the recirculation bores 24 of the flame tube 23. The recirculation bores 24 serve to stabilize the flame. During this process, aging gas is drawn in from the outside of the flame tube 23 via the recirculation bores 24 (Venturi effect). This aging gas then forms a protective layer around the flame.

[0071] In Fig. 2 are the same details as in Fig. 1 with the same reference numerals. Reference is made to the preceding description. In this figure, the collar 28 and the ring extension 29 on the support flange 15 are shown for the first time. The flange 13 with the mixing tube 21 is attached to the collar 28. An inserted support ring 30 sits in the ring extension 29, which supports the air control apparatus 32 as well as the fuel injection nozzle 31. Further details of the burner include swirl vanes 41 between the burner jacket 12 and the mixing tube 21, and an ignition device 45 with two electrodes 46, 47. A further through-bore 48 for the connection connections of the ignition device 45 is visible in the air supply manifold 34. Furthermore, it becomes clear that the flame tube 23 has a nozzle-like indentation 42 near the air control apparatus 32, in which circumferentially distributed gas supply holes 43 are provided, through which the primary recirculation gas quantity is drawn in.The central fuel injector 31 is supplied with fuel via a line (not shown) which enters the air supply manifold 34 through a through-bore 39. An internal shaft 65 for adjusting the swirl device and a coaxial hollow shaft 68 for adjusting the throttle plate enter the air supply manifold 34 through a further through-bore 40.

[0072] Details of the air control arrangement 32 and its adjustment mechanism are described with reference to the following figures.

[0073] In Fig. Figure 3 contains the same details as in the preceding figures, with the same reference numerals. Reference is made to the preceding description. It can be seen that the support ring 30 is connected to the flame tube 23 in the ring extension 29, as well as to the air control apparatus 32. This comprises a first ring disk 51 with a plurality of air passage holes 52, which has a central opening for receiving the fuel injection nozzle 31. Downstream of the ring disk 51 in the direction of flow, there is a rotatable ring disk 53 and a fixed ring disk 54. The two ring disks 53, 54 are separated from each other by an insulating disk 57. The ring disks together form a throttle orifice. They each have a central outlet opening 55 for the primary air and a ring of orifice plates 56 for the secondary air.The ring disc 53 can be rotated relative to the ring disc 54 by means of adjusting means not visible here, so that the apertures 56 in the ring disc 54 can be throttled or their through-cross-section reduced.

[0074] Between the two ring disks 51 and 53 extends an initially cylindrical and then funnel-shaped annular mantle 61, which separates an inner primary combustion airflow ring from an outer secondary combustion airflow ring. Within the annular mantle 61, and thus within the inner primary combustion airflow ring, circumferentially distributed adjustable swirl flaps 62 are located on radially arranged pivot pins 63. These flaps allow the swirl of the inner primary combustion airflow ring to be influenced, while the volume flow of the outer secondary combustion airflow ring can be adjusted by means of the adjustable apertures 56.

[0075] In Fig. Figure 4 contains identical details as in the preceding figures, designated with the same reference numerals. Reference is made to the preceding description. An adjusting device mounted in the through-bore 40 and in the first ring disk 51 is shown here. This device comprises a rotatable inner shaft 65, which engages an outer toothed ring 67 on the second ring disk 53 via a pinion 66, and a rotatable hollow shaft 68, which engages an adjusting ring 70 via a pinion 69 to rotate the swirl flaps 62. Drive pins 60 are arranged on the adjusting ring 70 and act on the swirl flaps 62, which are pivotable on pivot pins 63.

[0076] In Fig. Figure 5 shows a schematic diagram of a system for aging exhaust gas catalysts, which includes a burner 10 according to the invention as its central component. The system includes parts of a fuel supply 71 and parts of a combustion air supply 81.

[0077] The fuel supply system 71 includes a fuel tank 72, a fuel pre-supply pump 73, a low-pressure fuel pump 74, and a high-pressure fuel pump 75 with an electric motor. A mass flow sensor 76 is located downstream of the low-pressure fuel pump 74. A return loop parallel to the low-pressure fuel pump 74 comprises a pressure regulating valve 77 and a fuel recooler 78. A return loop parallel to the high-pressure pump 75 comprises a pressure regulating valve 79 and a fuel recooler 80.

[0078] An air filter 82 and a mass flow sensor 83 are visible on the combustion air supply 81. A throttle valve 84 and a Roots compressor 85 with a frequency-controlled electric motor are located downstream of this. A charge air cooler 86 is located in the combustion air duct behind the compressor 85, before it enters the burner 10.

[0079] When fuel and combustion air are supplied by means of the specified means 71, 81, the burner 10, after ignition by an ignition device (not shown here), produces aging gas, which can pass through exhaust catalysts 91, 92 and a diesel particulate filter 95. The exhaust catalysts can be, for example, TWC, DOC, SCR, or CDPF catalysts and are arranged parallel to each other. The main aging line 100 branches into two aging gas branch lines 115, 116 to the exhaust catalysts 91, 92 and a centrally located aging bypass line 119. Control valves 93, 94 are located upstream of the catalysts 91, 92 in the branch lines, and control valves 117, 118 are located downstream of the catalysts. These valves allow the mass flows to be distributed and, in particular, adjusted to be equal. In the bypass line 119 there is a metering valve 120 and a switching valve 121, with which the size of the bypass flow and thus the mass flows to the catalysts can be controlled.Upstream of the diesel particulate filter 95, the branch lines 115, 116 and the bypass line 119 are rejoined to form the main aging gas line 100. The adjustable burner 10 is used to perform specific operating cycles that ensure the standard-compliant aging of the exhaust catalysts 91, 92 and, if applicable, the diesel particulate filter 95.

[0080] The wiring diagram can be extended analogously for the application of additional catalysts connected in parallel.

[0081] The main flow of the treated aging gas is discharged from the main aging gas line 100 via an exhaust stack 101, while a partial flow is returned to the burner 10 as exhaust-treated secondary aging gas via a secondary return line 98. Optionally, aging gas can be diverted downstream of the burner 10 and upstream of the exhaust gas aftertreatment system via a secondary aging gas bypass line and returned to the burner as secondary aging gas. A control valve 122 for the exhaust-treated aging gas is located at the inlet to the return line 98, and a control valve for the untreated aging gas is located in the return line. These valves allow the composition of the secondary aging gas to be modified. The return line 98 for the secondary aging gas contains an exhaust gas heat exchanger 102 and a condensate separator 103 with a controllable drain valve 104.A mass flow sensor 105 is connected downstream of the condensate separator 103. Following this are a throttle valve 106 and a Roots compressor 107, which is driven by a frequency-controlled electric motor.

[0082] Before the return line 98 enters the burner 10, a return branch line 99 diverges and leads into the main aging gas line 100 downstream of the burner. A mixer 96 is installed downstream of this branch. This mixer can be used for so-called tertiary aging gas recirculation. A controllable shut-off valve 109 is located in the return branch line 99. Liquids such as oil or fuel, or other gases, can be added to the tertiary aging gas via a mixer 108. Branch lines 112 and 113, each with controllable inlet valves 110 and 111, are provided for these additions to the mixer 108. From the return branch line 99, an aging gas bypass line 123 branches off, bypassing the mixer 96 in the bypass to the aging gas main line and branching off into two branch lines 125, 126 for cooled and conditioned aging gas, which each lead into the aging gas branch lines 115, 116 to the exhaust gas catalysts 91, 92.In branch lines 125, 126, control valves 127, 128 are installed for measuring the proportion of cooled aging gas, with which the aging gas temperature in the exhaust gas catalysts can be influenced, in particular lowered.

[0083] In Fig. 6 shows a completed system in side view, opposite it in Fig. The system shown in diagram 5 is simplified.

[0084] A burner 10 is visible, encased in an insulating jacket 50, and fitted with two exhaust catalysts 91', 92' connected in series, as well as a diesel particulate filter 95. The aging gas main line 100 opens into an exhaust stack 101. A return line 98 branches off from this main line, in which an aging gas recooler 102 is located. Downstream of the recooler is a condensate separator 103 with a drain valve 104. Downstream of this, a mass flow sensor 105 and a throttle valve 106 are provided in the return line 98. Downstream of the throttle valve 105, a Roots compressor 107 is visible in the line 98, which can be driven by a frequency-controlled electric motor. Downstream of the Roots compressor, the return line 98 opens laterally into the burner 10 in the initial region of the combustion chamber.While the fuel supply system is not shown here, the air supply system 81 includes the air filter 83, the throttle valve 84, the Roots compressor 85, which can be driven by a frequency-controlled electric motor, and the charge air cooler 86.

[0085] Fig. Figure 7 shows a diagram of an example OSC measurement based on lambda values ​​over time, measured with a lambda sensor installed upstream of the catalytic converter (the signal of which is labeled "lambda before the catalytic converter") and with a lambda sensor installed downstream of the catalytic converter (the signal of which is labeled "lambda after the catalytic converter"). OSC measurements are performed to determine the aging of a catalytic converter. This measurement serves to determine the oxygen storage capacity of the catalytic converter, from which its aging state can then be derived. The older the catalytic converter, the lower its oxygen storage capacity. OSC measurements are used both in production vehicles and in artificial catalytic converter aging.

[0086] The OSC measurement is performed under steady-state conditions of exhaust gas temperature and mass flow. Lambda signals are measured before and after the catalytic converter. The burner is then supplied with fuel in such a way that the exhaust gas quickly transitions from a rich mixture (Lambda < 1) to a lean mixture (Lambda > 1), with the desired profile represented by the "Lambda Target" curve. The phase shift between the pre-catalytic converter signal ("Lambda before catalytic converter") and the post-catalytic converter signal ("Lambda after catalytic converter") is proportional to the oxygen stored in the catalytic converter. Fig. Figure 7 shows such a measurement on the catalyst aging test bench.

[0087] The catalyst measured here still has a high oxygen storage capacity. It is clearly visible that the lambda signal after the catalyst (lambda after the catalyst) rises more slowly than the lambda signal before the catalyst (lambda before the catalyst) and only reaches its peak value seconds later. A borderline catalyst, on the other hand, exhibits different behavior. Shortly after the lambda signal from the sensor before the catalyst reaches its peak value, the lambda value at the sensor after the catalyst would also reach its maximum. Both lambda signals would rise almost simultaneously.

[0088] Fig.Figure 8 shows the diagram of the ZDAKW cycle, developed by the Exhaust Gas Center of the German Automotive Industry (ADA). It depicts the target temperature T-target over time, where the target value of the air-fuel ratio λ-target is 1, except during the overrun fuel cut-off phases, in which the air-fuel ratio λ is set to a value greater than or equal to 8. This cycle essentially consists of a high-temperature phase with five overrun fuel cut-offs and a de-icing phase with three temperature levels. During overrun fuel cut-off, fuel injection is briefly interrupted and the exhaust gas recirculation mass flow is simultaneously reduced. This purges the catalytic converter with oxygen and establishes a lambda value greater than or equal to 8. When the exhaust gas recirculation mass flow is subsequently increased and injection resumes, the lambda value rises again to the regulated value of λ = 1.This process is designed to simulate driving during sudden acceleration and deceleration. During the poisoning phase, a slightly richer exhaust gas mixture is passed over the catalytic converter at low temperatures. This results in a reduction of the catalytically active layer due to chemical poisoning.

[0089] The high-temperature phase, lasting 600 seconds each, is repeated 48 times. The poisoning phase, lasting 30 minutes each, is repeated 8 times; the entire cycle lasts 96 hours. The total cycle corresponds to a driving distance of 80,000 km. Reference symbol list 10 burners 11 Combustion chamber 12 Burner mantle 13 Entry flange 14 Exit flange 15 Carrier flange 16 first section (12) 17 second section (12) 18 third section (12) 19 Transition section 20 Transition section 21 Mixing tube 22 Inlet opening 23 Flame tube 24 Recirculation opening 25 Mixing device 26 Aging gas return pipe 28 Federal 29 Ring attachment 30 carrier ring 31 Fuel injector 32 Air control apparatus 33 Carrier flange 34 Air intake manifold 35 Inner jacket 36 Outer jacket 38 shell space 39 through-tubes 40 through-pipes 41 Swirl blade 42 Nozzle section 43 Exit opening 45 Ignition device 46 electrode 47 Electrode 48 through-tubes 50 insulating jacket 51 Ring disc 52 Air passage hole 53 Ring disc (rotatable) 54 Ring disc (fixed) 55 Outlet opening (primary air) 56 perforated apertures (secondary air) 57 Insulating washer 60 drive pins 61 Ring mantle, funnel 62 Swirl flap 63 cones 65 inner shaft 66 sprockets 67 Outer toothed ring 68 Hollow shaft 69 sprockets 70 adjusting ring 71 Fuel supply system 72 Fuel tank 73 Fuel pre-supply pump 74 Low-pressure fuel pump 75 High-pressure fuel pump 76 Mass flow sensor 77 Pressure regulating valve 78 Fuel coolers 79 Pressure regulating valve 80 fuel coolers 81 Combustion air supply system 82 air filters 83 Mass flow sensor 84 Throttle valve 85 compressors 86 Intercoolers 91 Exhaust catalyst 92 Exhaust catalyst 93 Throttle valve 94 Throttle valve 95 Diesel particulate filters 96 Mixing device 98 Aging gas return line (secondary) 99 Aging gas return line (tertiary) 100 Aging gas main line 101 Fireplace 102 Exhaust gas recirculation cooler 103 Condensate separators 104 Drain valve 105 Mass flow sensor 106 Throttle valve 107 compressors 108 mixers 109 Shut-off valve 110 Inlet valve 111 Inlet valve 112 Branch line 113 Branch line 115 Aging gas branch line 116 Aging gas branch line 117 Control valve 118 Control valve 119 Aging gas bypass line 120 switching valve 121 Metering valve 122 Control valve 123 Aging gas bypass line 125 Branch Management 126 Branch Management 127 Control valve 128 Control valve

Claims

[1] Method for generating aging gas for aging components for exhaust gas aftertreatment in a burner (10) which has a combustion chamber (11) with at least one fuel injection nozzle (31) and with a combustion air supply with means for generating swirl (62), wherein the swirl of the combustion air is adjusted depending on the selected combustion air ratio λ, characterized by , that to simulate a vehicle overrun shutdown after an interruption of the fuel supply to restart the combustion chamber (11) a combustion air ratio λ < 1 (rich) and a high swirl of a primary air flow is set. [2] Method according to claim 1, characterized by , that the swirl of the combustion air is changed depending on changes in the combustion air ratio λ during the generation of aging gases. [3] Method according to one of claims 1 or 2, characterized by, that the swirl of the combustion air is set lower at a combustion air ratio λ≥1 (lean / stoichiometric) and higher at a combustion air ratio λ<1 (rich). [4] Method according to any one of claims 1 to 3, characterized by that the total flow of combustion air is mass flow controllable. [5] Method according to any one of claims 1 to 4, characterized by , that the combustion air is divided into an inner primary air stream and an outer secondary air stream, whereby the combustion air in the inner primary air stream is supplied in a swirling manner. [6] Method according to claim 5, characterized by that the combustion air in the outer secondary air stream is supplied essentially without swirl. [7] Method according to any one of claims 5 to 6, characterized by, that the secondary airflow can be throttled, wherein the secondary airflow is throttled in particular to achieve a combustion air ratio λ<1 (rich). [8] Method according to any one of claims 1 to 7, characterized by , that an axial position of the burner flame within the combustion chamber (11) is detected and, if the burner flame migrates backwards, the swirl of the combustion air is increased and, if the burner flame migrates forwards, the swirl of the combustion air is reduced. [9] Method according to any one of claims 1 to 8, characterized by , that for primary aging gas recirculation, aging gas from the combustion chamber (11) is recirculated in a shell flow into the area of ​​the fuel injection nozzle (31). [10] Method according to claim 9, characterized by , that when the secondary airflow is throttled, the primary aging gas recirculation is also reduced. [11] Method according to any one of claims 1 to 10, characterized by , that aging gas conditioned for secondary aging gas recirculation is added to the aging gas originally generated in the burner (10) in the combustion chamber (11), in particular gas that has previously been subjected to exhaust gas aftertreatment. [12] Method according to claim 11, characterized by , that the proportion of the conditioned aging gas in the secondary aging gas recirculation is changed to maintain a predetermined aging gas temperature. [13] Method according to one of claims 11 or 12, characterized by , that the conditioned aging gas is added to the secondary aging gas recirculation in the burner (10) in the form of an annular jacket flow. [14] Method according to any one of claims 1 to 13, characterized by , that for tertiary aging gas recirculation, conditioned aging gas is added to the aging gas generated in the burner (10) behind the burner (10) and before the exhaust gas aftertreatment components. [15] Method according to claim 14, characterized by , that oil and / or fuel and / or foreign gas and / or air is added to the conditioned aging gas of the tertiary aging gas recirculation. [16] Method according to any one of claims 1 to 15, characterized by that the fuel injection is pulse-controlled with a minimum pre-pressure of 20 bar. [17] Method for aging exhaust aftertreatment components by exposure to aging gas, characterized by , that the aging gas for the application to the exhaust aftertreatment components is produced according to the method according to one of claims 1 to 16. [18] Burner (10) for generating aging gas for aging components for exhaust aftertreatment, comprising a combustion chamber (11) with a combustion chamber axis and at least one fuel injection nozzle (31) and a combustion air supply (34), which has means for generating swirl (62), wherein the means for generating swirl (62) are adjustable in the sense of changing the swirl strength, characterized by , that within a burner jacket (12) a mixing tube (21) arranged concentrically to the combustion chamber axis is located, which forms an annular space with the burner jacket (12), to which a feed nozzle (26) for conditioned aging gas is connected, wherein the mixing tube (21) extends beyond the length of a flame tube (23) and has circumferentially distributed outlet openings (22) for the conditioned aging gas of the secondary aging gas recirculation behind the end of the flame tube (23). [19] Burner (10) according to claim 18, characterized by, that an annular mantle or funnel (61) is located in the combustion air stream upstream of the fuel injector (31), which divides the combustion air stream into an inner primary air stream and an outer secondary air stream, wherein means for generating swirl (62) are located in the primary air stream. [20] Burner (10) according to claim 19, characterized by , that the means for generating swirl (62) are located exclusively in the primary airflow. [21] Burner (10) according to one of claims 18 to 20, characterized by , that the means for generating swirl (62) comprise circumferentially distributed swirl vanes (62) which are pivotable on axes arranged radially to the combustion chamber axis. [22] Burner (10) according to one of claims 18 to 21, characterized by , that means for volume flow control (56) of the combustion air flow are provided in the burner. [23] Burner (10) according to claim 22, characterized by, that the means for controlling the volume flow (56) of the combustion air flow are arranged in a ring shape in the secondary air flow. [24] Burner (10) according to one of claims 22 or 23, characterized by , that the means for controlling the volume flow (56) of the combustion air flow consists of a ring of adjustable apertures (56) arranged concentrically to the fuel injector nozzle (31). [25] Burner (10) according to any one of claims 18 to 24, characterized by , that means for detecting the axial flame position are arranged in the combustion chamber (11), in particular a temperature sensor or several temperature sensors distributed over the length of the combustion chamber. [26] Burner (10) according to any one of claims 18 to 25, characterized by, that the flame tube (23) is arranged concentrically in the combustion chamber (11) and terminates before the end of the combustion chamber (11) and has circumferentially distributed openings (43) near the fuel injection nozzle (31) for backflowing aging gas of the primary aging gas recirculation. [27] Burner (10) according to claim 26, characterized by , that the outlet openings (43) in the flame tube (23) are located in a nozzle-like narrowed section (42) of the flame tube (23). [28] Burner (10) according to any one of claims 18 to 27, characterized by , that the fuel injector (31) is supplied by a pulse-controlled high-pressure injector. [29] Burner (10) according to claim 28, characterized by , that the fuel injector nozzle (31) is combined with the high-pressure injector in a single unit and is arranged within the means for generating swirl (62). [30] System for aging exhaust gas aftertreatment components by applying aging gas generated in a burner (10), wherein a burner (10) according to one of claims 18 to 29 is provided, to which the exhaust gas aftertreatment components are connected via an aging gas line (100), characterized by , that the feed nozzle (26) is connected to a line (98) for aging gas produced in the burner (10) and subsequently conditioned. [31] Plant according to claim 30, characterized by , that an aging gas recooler (102) is arranged in the line (98). [32] Plant according to one of claims 30 or 31, characterized by , that a throttle valve (106) and a controllably driven compressor (107) are arranged in the line (98). [33] Plant according to any one of claims 30 to 32, characterized by, that the line (98) is connected to an aging gas main line (100) downstream of the aging gas aftertreatment components or to an aging gas bypass line in the bypass to the exhaust gas aftertreatment components. [34] Plant according to any one of claims 30 to 33, characterized by , that a branch line (99) branches off from the line (98) for conditioned aging gas before the connection to the supply nozzle (26), which flows into the main aging gas line (100) behind the burner (10). [35] Plant according to claim 34, characterized by , that feed lines (112, 113) for oil and / or fuel and / or foreign gas and / or air feed into the branch line (99).

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