DE102021127949A1 - Drive arrangement for a mobile, mobile with the drive arrangement and method for exhaust gas purification in the drive arrangement and/or in the mobile - Google Patents

Abstract

It is the object of the present invention to form a drive arrangement with improved exhaust gas behavior. A drive arrangement 1 for a mobile 2 is proposed with a first thermal conversion engine 3 for generating a first drive torque for the mobile 2, the first conversion engine 3 having an exhaust gas outlet 6 for discharging exhaust gas from the first conversion engine 3, with a second thermal conversion engine 7 , the second conversion engine 7 having a gas inlet 9 , the exhaust gas outlet 6 being fluidically connected to the gas inlet 9 , so that the second conversion engine 7 thermally converts the exhaust gas from the first conversion engine 3 .

Description

The invention relates to a drive arrangement for a mobile vehicle with exhaust gas cleaning. The invention also relates to a vehicle with the drive arrangement and a method for cleaning exhaust gases in the drive arrangement and/or in the mobile.

• ■ weitere Konzentration auf Real-Driving Emissions (RDE) sicherstellen
• ■ Kraftstoff- und Technologieneutralität erreichen
• ■ Beruhend auf einer ganzheitlichen Analyse auf Lebenszyklusbasis Gesetze erlassen

In its European Green Deal concept, the European Commission announced a new bill for stricter standards for pollutant emissions from cars, vans, buses and trucks for 2021. In order to sustainably improve European air quality, the Euro 7 regulation offers a unique opportunity to implement a regulatory framework that takes into account the following overarching principles:

• ■ Ensure further focus on Real Driving Emissions (RDE).
• ■ Achieve fuel and technology neutrality
• ■ Legislate based on a holistic life cycle analysis

The announced stricter pollutant standard Euro 7 is likely to have a major impact on the choice of technology at a reasonable cost-benefit ratio. Consequently, a realistic implementation of the CO2 targets will most likely take place via a greater use of e-fuels, hybrid drives (HEV) and in the long term through H2 technology in a carbon-neutral approach. Current studies and sales figures as well as forecasts point to a symbiosis of thermochemical energy conversion machines with electric drives and thus show the need to further reduce pollutant emissions from internal combustion engines.

Current regulations on pollutant emissions take into account unburned hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO, NO2 - both collectively referred to as NOx -), particulate matter (mass: PM and number: PN) and CO2.

• 1) Innermotorischen Maßnahmen, zur Absenkung der Rohemissionen
• 2) Außermotorischen Maßnahmen in Form eines dem Motor nachgeschalteten Abgasnachbehandlungssystems.
• 3) Eine Kombination aus 1) und 2).

When it comes to reducing pollutant emissions from combustion engines, a distinction is made between:

• 1) Internal engine measures to reduce raw emissions
• 2) Measures outside of the engine in the form of an exhaust aftertreatment system downstream of the engine.
• 3) A combination of 1) and 2).

The combination of 1) and 2) also represents the state of the art for all mobile applications to meet the current emission standards. As a rule, internal engine measures are used to reduce raw emissions (engine-out) to such an extent that the downstream exhaust gas aftertreatment system cannot unnecessarily complex and expensive. The internal engine measures also include exhaust gas recirculation (EGR), which is often seen as a necessary evil. EGR lowers the oxygen content and the process temperature, causing a reduction in NOx. The further reduction of NOx (referred to as deNOx technology) usually takes place by means of selective catalytic reduction (SCR). The reducing agent used in the SCR is an aqueous urea solution with the commercial name AdBlue. Depending on the NOx concentration in the raw exhaust gas (engine-out) and the condition of the engine, Adblue is injected to reduce it to nitrogen, carbon dioxide (CO2) and water. The resulting CO2 is an undesirable by-product of the SCR technology and thus contributes to an increase in the CO2 emissions of the combustion engine.

It is the object of the present invention to propose a drive arrangement with improved exhaust gas behavior. This object is achieved by a drive arrangement having the features of claim 1, by a mobile having the features of claim 11 and by a method for cleaning exhaust gases having the features of claim 13. Preferred or advantageous embodiments result from the dependent claims, the following description and the attached figures.

The subject matter of the invention is a drive arrangement which is suitable and/or designed for a mobile vehicle. The mobile is designed in particular as a movable object, in particular a self-movable object.

In particular, the drive arrangement provides an overall drive torque for the mobile. In particular, the drive arrangement serves to accelerate and/or drive the mobile to a speed greater than 10 km/h, preferably greater than 40 km/h.

The drive assembly includes a first thermal conversion motor. The first conversion engine is designed to generate a first drive torque for the mobile. Optionally, the first drive torque can correspond to the total drive torque of the mobile. The first converted engine has an exhaust outlet for discharging exhaust gas from the first converted engine.

The drive assembly includes a second thermal conversion engine, the second thermal conversion engine having a gas inlet. In particular, the gas inlet serves to take over gas, in particular with a proportion of ambient air, in order to enable the thermal conversion, in particular combustion during the thermal conversion.

In particular, the fuel of the first and/or the second conversion engine is combusted. The first and/or the second conversion motor is designed as an internal combustion engine, for example. The first and/or second conversion engine thermally converts a fuel to convert chemical energy into thermal energy and subsequently into mechanical energy.

In the context of the invention, it is proposed that the exhaust gas outlet is fluidically connected to the gas inlet, so that the second conversion engine thermally converts the exhaust gas from the first conversion engine, in particular also converts it, in particular burns it.

The entire and/or complete exhaust gas mass flow of the first conversion engine is preferably conducted via the exhaust gas outlet and/or via the gas inlet into the second conversion engine for thermal conversion. In the event that the first conversion engine has exhaust gas recirculation, the entire and/or complete non-recirculated portion of the exhaust gas mass flow of the first conversion engine is preferably conducted via the exhaust gas outlet and/or via the gas inlet into the second conversion engine for thermal conversion. The thermal conversion in the second conversion engine of the exhaust gas corresponds in particular to exhaust gas purification by post-combustion.

The drive arrangement can also have a number of such second conversion motors.

It is a consideration of the invention that typical exhaust gas aftertreatment systems with an increasing number of components, actuators, sensors, etc. have a high level of complexity and thus increased production costs. Furthermore, the active and passive components in the typical exhaust aftertreatment systems lead to a limited service life of the components. It should also not be underestimated that the use of additional resources, such as uric acid (“AdBlue”) in the exhaust aftertreatment systems, increases the proportion of CO2 emitted. In contrast, the invention proposes replacing part or all of the exhaust gas aftertreatment system with the second thermal conversion engine. In particular, critical emissions, in particular NOx, can be reduced by the thermal conversion.

In a preferred implementation of the invention, the second conversion engine has a fuel supply for supplying ammonia or a precursor of ammonia. In particular, the ammonia or the precursor of ammonia constitutes a main fuel for the second conversion engine. A precursor of ammonia is to be understood, for example, as uric acid or the known AdBlue mixtures. Optionally, the second conversion engine can be supplemented with hydrogen to improve combustion. A large number of advantages can be exploited by using ammonia or a corresponding precursor of ammonia.

Ammonia can be considered a hydrogen carrier and used as a fuel. It is considered to be of long-term interest, especially as a fuel for maritime transport. Ammonia can be considered a so-called 'Electric Fuel' (e-fuel) because it can be produced by the electrolysis of water and subsequent catalytic conversion of hydrogen and nitrogen (from the air) into ammonia. Unlike most other electric fuels, ammonia can be produced without using a carbon source. Only electricity, water and air are required, which is advantageous in many ways. The electricity could be generated from wind or hydroelectric power, or from other sustainable sources, so the ammonia produced is a sustainable fuel. In particular, during thermal conversion, ammonia burns without producing CO2.

The fuel (NH3) of the second conversion engine also acts as a reducing agent for the NOx in the exhaust gas of the first conversion engine. The NOx are reduced to N2 by selective non-catalytic reduction (SNCR) in the combustion chamber(s) of the second conversion engine. This occurs after the reaction: NH2 + NO -> N2 + H2O.

In a preferred embodiment, the drive arrangement has a generator for converting mechanical energy into electrical energy. The generator is drivingly coupled to the second conversion motor. The second conversion engine thus assumes the function of supplying energy in addition to the function of cleaning exhaust gases. This can be particularly efficient in particular in connection with ammonia or a precursor of ammonia as a fuel for the second conversion engine, since ammonia has a calorific value similar to that of gasoline having. The second conversion engine thus combines the tasks of an exhaust aftertreatment system and a "bottoming cycle" in the form of power generation. In this case, a "bottoming cycle" is a downstream process, designed as a thermodynamic process or cycle, in which electricity is generated from waste heat. Thus, the chemical energy in the exhaust gas cleaning in the second conversion engine is not released into the environment, but converted via the mechanical energy into electrical energy and reused in the vehicle.

The electrical energy obtained can, for example, be stored in an energy storage device, for example in an accumulator, or be consumed.

It is particularly preferred that the second conversion motor is drivingly coupled exclusively to the generator. The entire mechanical energy of the second conversion engine is thus passed on to the generator for conversion into electrical energy. This refinement simplifies the architecture of the drive arrangement since the second conversion motor does not have to be integrated into a mechanical drive train of the drive arrangement.

In a preferred implementation of the invention, the second conversion engine is designed as a two-stroke engine. Two-stroke engines are characterized by low complexity, in particular no valves are required in two-stroke engines.

By choosing the two-stroke engine as the second conversion engine, the complexity of the system technology for exhaust gas purification is further reduced.

In a possible development of the invention, the second conversion engine is designed as a centrifugal engine and/or as a rotary piston engine and/or as a rotary engine. For example, this can be implemented as a Wankel engine.

• - einen scheibenförmigen Rotor mit einer ersten Drehachse, die rechtwinklig zur Ebene des Rotors steht und in einer Orientierungsebene liegt,
• - ein im Wesentlichen scheibenförmiges Schwingelement mit einer zweiten Drehachse, die in der Ebene des scheibenförmigen Schwingelements und in der Orientierungsebene liegt, wobei die zweite Drehachse einen Winkel mit der ersten Drehachse in der Orientierungsebene bildet;
• - ein im Wesentlichen kugelförmiges Gehäuse, das den Rotor und das Schwingelement umgibt und in Kombination damit vier (De)Kompressionskammern bildet;
• - einen Verbindungskörper, der den Rotor und das Schwingelement im Gehäuse relativ zueinander verschiebbar positioniert und die vier (De)Kompressionskammern abdichtet;

wobei die Vorrichtung ferner mit einem Kraftantrieb und einer mechanischen Verbindung zwischen dem Kraftantrieb und dem Rotor versehen ist, wobei der Kraftantrieb konfiguriert ist, um Kraft an die Rotationsmaschine zu liefern oder aufzunehmen.Particularly preferably, the second conversion motor is designed as a rotary machine for compression and decompression. Preferably, the rotary machine comprises

• - a disk-shaped rotor with a first axis of rotation which is perpendicular to the plane of the rotor and lies in an orientation plane,
• - a substantially disk-shaped oscillating element having a second axis of rotation lying in the plane of the disk-shaped oscillating element and in the orientation plane, the second axis of rotation forming an angle with the first axis of rotation in the orientation plane;
• - a substantially spherical housing which surrounds the rotor and the vibrating element and in combination therewith forms four (de)compression chambers;
• - a connecting body which positions the rotor and the vibrating element in the housing in a relatively slidable manner and seals the four (de)compression chambers;

the device being further provided with a power driver and a mechanical connection between the power driver and the rotor, the power driver being configured to supply or receive power to the rotary machine.

In particular, the generator is integrated in the rotary machine, the generator having a stator section and a rotor section, the rotor section being driven by the rotor and the stator being arranged on the housing. The rotary machine is preferably designed as a two-stroke engine. In particular, the rotary machine after WO 2012002816 A educated. In this regard, reference is made to the application WO 2012002816 A , the content of which is hereby incorporated into this application.

Optionally, the drive arrangement has an electric machine for driving the mobile. The electric machine provides a second drive torque for the mobile, the total drive torque being formed by the first drive torque and the second drive torque. The electrical machine is supplied with electrical energy directly by the generator and/or indirectly via the energy storage device, or at least is also supplied with it. In this embodiment, the chemical energy from the fuel for the second conversion engine is used to drive the vehicle, so that the exhaust gas cleaning is carried out in a quasi-energy-neutral manner.

In a first possible embodiment of the invention, the first conversion motor works with a fossil fuel. In particular, the fuel is in the form of diesel, petrol or natural gas, in particular methane. With these fuels, the cleaning of the exhaust gases from nitrogen oxides is particularly complex. In particular, it should be noted that methane is the main component of natural gas. In lean operation (increased excess air) of natural gas engines, methane slip (fuel that does not take part in combustion and escapes from the engine with the exhaust gases) poses a major challenge high activation temperature for methane oxidation. While other unburned hydrocarbons are oxidized in a conventional catalyst, the catalytic post-oxidation of methane is difficult. In the second conversion engine, the methane is given a second chance to react in the high temperature gas phase oxidation.

In an alternative embodiment of the invention, the first conversion engine is based on a renewable fuel, in particular based on hydrogen or eFuels. The combustion of renewable fuels produces a particularly large amount of NOx, which, in view of the planned legal regulations, will not have to be eliminated in the near future. Here, the invention helps to implement increased environmental and thus climate protection beyond the legal requirements.

A further object of the invention is formed by a mobile which has a drive arrangement as described above and/or according to one of the preceding claims.

In particular, the mobile is implemented as a vehicle, with the total drive torque driving the vehicle. The mobile is particularly preferably designed as a hybrid vehicle, this having the additional electrical machine for generating the second drive torque.

In an alternative embodiment of the invention, the mobile is implemented as a boat, an aircraft, etc. In particular, the drive arrangement can be used with any type of mobile.

A further object of the invention is formed by a method for exhaust gas purification in the drive arrangement and/or in the mobile as described above, wherein exhaust gases are generated in the first conversion engine and the exhaust gases are thermally converted in the second conversion engine, to carry out exhaust gas cleaning.

• 1 eine schematische Blockdarstellung von einem Mobil mit einer Antriebsanordnung als ein Ausführungsbeispiel der Erfindung.

Further features, advantages and effects of the invention result from the following description of a preferred exemplary embodiment of the invention and the attached figure. This shows:

• 1 a schematic block diagram of a mobile with a drive arrangement as an embodiment of the invention.

The 1 shows a drive arrangement 1 for a mobile 2 in a schematic block diagram, wherein the mobile 2 is designed, for example, as an automobile. The drive arrangement 1 has the function of providing a total drive torque for the mobile 2 so that it can accelerate to a driving speed.

The drive arrangement 1 has a first thermal conversion engine 3, the first thermal conversion engine 3 being designed as an internal combustion engine. The first conversion motor 3 has the function of generating a first drive torque for the mobile 2 . The first drive torque forms part of the total drive torque. A thermal conversion of a fuel takes place in the first conversion engine 3 , the fuel being supplied to the first conversion engine 3 starting from a tank 4 . In addition, ambient air is optionally supplied to the conversion engine 3 via a compressor 5 . The fuel can, for example, be mixed with the compressed ambient air downstream of the compressor 5 (port injection). Alternatively, the fuel can be injected directly into a combustion chamber of the conversion engine 3 .

Gasoline, diesel, methane, hydrogen and/or artificial fuels, such as eFuels, can be arranged as fuel in the tank 4 .

The first conversion engine 3 has an exhaust gas outlet 6 , exhaust gases from the thermal conversion of the fuel being discharged from the first conversion engine 3 via the exhaust gas outlet 6 .

The drive arrangement 1 has a second thermal conversion motor 7, the second conversion motor 7 also being designed as an internal combustion engine. The second conversion engine 7 is supplied with fuel via a second tank 8, the fuel in the second tank 8 being ammonia or a precursor of ammonia. Optionally, hydrogen can also be supplied, but the ammonia or the precursor of ammonia forms the main fuel for the second conversion engine 7.

The second conversion engine 7 has a gas inlet 9, the gas inlet 9 optionally being fluidically connected to the gas outlet 6 via an expander 10, so that the exhaust gases from the first conversion engine 3 are passed on to the second conversion engine 7 for thermal conversion. The compressor 5 and the expander 10 form a charging group, in particular a turbocharger or turbocharger, but this is optional. In particular, exhaust gases are mixed with the fuel from the second tank 8 and subsequently converted thermally, in particular burned.

The drive arrangement 1 has a generator 11, the generator 11 being drive-connected to the second conversion motor 7. In a concrete embodiment, the generator 11 can be integrated in the second conversion motor 7 .

Through the fuel supplied from the second tank 8 and the exhaust gases from the first conversion engine 3 supplied via the gas inlet 9, the thermal conversion ensures that the exhaust gases are cleaned and, on the other hand, the conversion of the chemical energy of the Fuel via thermal energy and subsequently into electrical energy via the generator 11, the exhaust gas cleaning by the thermal conversion of the exhaust gases is not an energetic loss process, but the chemical energy expended therein as electrical energy via the generator 11 is dissipated again.

The drive arrangement 1 has an electric machine 12, the electric machine 12 providing a second drive torque, the second drive torque forming part of the total drive torque. The first drive torque and the second drive torque can form the total drive torque in parallel or alternatively. On the one hand, the generator 11 is connected directly to the electrical machine 12 so that the electrical current can be consumed directly by the electrical machine 12 . Alternatively, the generator 11 is indirectly connected to the electrical machine via an energy storage device 13, so that electrical energy is first temporarily stored and only subsequently released. It is also possible that a further source of electrical energy or a further electrical energy store is provided.

In particular, the disadvantages of exhaust gas aftertreatment should be largely eliminated. These are: complexity, costs, resources (precious metals), service life of the components, large number of catalytic converters, sensors and actuators connected in series, complex control (also affecting engine management) and additional operating media (AdBlue) with a CO ₂ contribution.

The drive arrangement 1 comprises the combination of the second conversion engine 7 and the generator 11, in particular designed as a compact motor-generator which has the function of an exhaust gas treatment system and a “bottoming cycle”. The motor-generator is the first conversion engine 3 downstream as an internal combustion engine, which represents the main drive. The entire exhaust gas mass flow leaving the internal combustion engine is introduced into the motor generator. The motor-generator consists of, for example, a spherical-like case, with the stator of the generator 11 being located in the equator of the case. The rotor of the generator 11 represents the rotating engine. This means that all the work produced is converted directly into electricity in the combustion chambers of the motor-generator. The engine of the motor generator ideally works according to the 2-stroke principle and sucks in the entire exhaust gas mass flow of the upstream main drive. The main drive can be operated with fossil or synthetic fuels. Ammonia (NH3), which could also be doped with hydrogen (H2), is injected into the engine of the motor generator. Injection takes place either in the intake tract or directly in the combustion chamber. A combination of manifold and direct injection is also possible. In addition to CO2, H2O, N2 and residual oxygen (O2) in the range of 1% to 15%, the exhaust gases from the main drive also contain pollutants such as unburned hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx). HC and CO are oxidized to CO2 in the motor generator engine. The fuel (NH3) of the motor-generator also acts as a reducing agent for the NOx. NOx is reduced to N2 by selective non-catalytic reduction (SNCR) in the engine's combustion chambers. This occurs after the reaction: NH2 + NO -> N2 + H2O. The motor generator thus combines the tasks of an exhaust aftertreatment system and a "bottoming cycle" in the form of a serial hybrid system.

The main drive can be designed without internal engine measures for NOx reduction, in particular without EGR, and optimized to maximize efficiency. This increases its service life and the acquisition and operating costs (cost of ownership) can be reduced. In addition, the power split between the main drive and the "bottoming cycle" can be optimized depending on the operating point and the required overall system performance. Thus, the CO2 emissions of the main drive can be reduced at least by the power share of the "bottoming cycle". If, for example, 20% of the requested power is provided by the motor-generator with a carbon-free fuel such as NH3, the CO2 emissions of the main engine, which burns a carbon-containing fuel, are reduced by the same percentage because these only provide 80% of the total power should.

• ▪ Ersetzung eines Teils oder des gesamten Abgasnachbehandlungssystems und dessen Komplexität z.B. für EU7 und/ oder für Heavy-Duty, Off-Road, Marine-& Stationär Anwendungen ähnliche Emissionsnormen.
• ▪ Realisierung eines „bottoming cycle“ in einem kompakten Motor-Generator, welcher einem, mit fossilen und/oder kohlenstoffneutralen Brennstoffen betriebenen, Verbrennungsmotor nachgeschaltet wird.
• ▪ Der gesamte Abgasmassenstrom des vorgeschalteten Motors fließt durch einen oder mehreren parallelgeschalteten Motor-Generatoren zwecks Abgasreinigung und gleichzeitiger Stromerzeugung in einer Hybridstrategie für die Speisung von Elektromotoren oder zur Batteriespeicherung.
• ▪ Jeder nachgeschaltete Motor-Generator übernimmt die Reduktion der Emissionen, insbesondere von NOx, unverbrannten Kohlenwasserstoffen (HC), Kohlenmonoxid (CO), Ruß, aber auch von, noch nicht reglementierten, Zwischenprodukte wie Formaldehyd, etc. Dies wird durch eine exotherme Reaktion erzielt, bei der dem Abgasmassenstrom ein kohlenstoffneutraler Kraftstoff und zugleich Reduktionsmittel wie Ammoniak (NH3) zugefügt wird. Der kohlenstoffneutrale Kraftstoff wird entweder vorm Eintritt in den Motor-Generator mit dem Abgasstrom des Hauptantriebs vorgemischt oder wird direkt in die Brennkammer eingespritzt.
• ▪ Der nachgeschaltete Motor-Generator wird - idealerweise kugelförmig - sehr kompakt ausgeführt, sodass seine Skalierung, analog dem Hubraum des vorgeschalteten Motors, ohne Einbuße in Platzverhältnissen gestaltet werden kann. Somit bewirkt eine Verdopplung des Durchmessers vom Motor-Generator eine achtfache Vergrößerung seines Hubraums.
• ▪ Ein elektrisch-angetriebener Verdichter kann vom Motor-Generator elektrisch gespeist werden, um den Teillastbetrieb des Verbrennungsmotors zu unterstützen.
• ▪ Methan (CH₄) slip aus lean-burn Gasmotoren kann in dem Motor-Generator oxidiert werden und benötigt keinen aufwendigen Methan-Katalysator, insbesondere kann hier der Methanschlupf ohne Katalysator oder mit weniger Katalysatoraufwand gereinigt werden.

Important points are therefore:

• ▪ Replacement of a part or the entire exhaust aftertreatment system and its complexity, e.g. for EU7 and/or for heavy Duty, off-road, marine & stationary applications have similar emission standards.
• ▪ Realization of a "bottoming cycle" in a compact motor-generator, which is connected downstream of an internal combustion engine operated with fossil and/or carbon-neutral fuels.
• ▪ The entire exhaust gas mass flow of the upstream engine flows through one or more motor-generators connected in parallel for the purpose of exhaust gas cleaning and simultaneous electricity generation in a hybrid strategy for feeding electric motors or for battery storage.
• ▪ Each downstream motor-generator reduces emissions, particularly NOx, unburned hydrocarbons (HC), carbon monoxide (CO), soot, but also intermediate products that are not yet regulated, such as formaldehyde, etc. This is achieved through an exothermic reaction , in which a carbon-neutral fuel and reducing agent such as ammonia (NH3) are added to the exhaust gas mass flow. The carbon-neutral fuel is either premixed with the exhaust stream of the prime mover before entering the motor-generator or is injected directly into the combustion chamber.
• ▪ The downstream motor-generator is designed to be very compact - ideally spherical - so that it can be scaled in the same way as the displacement of the upstream motor without sacrificing space. Thus, doubling the diameter of the motor-generator results in an eight-fold increase in displacement.
• ▪ An electrically-driven compressor can be electrically powered by the motor-generator to support the part-load operation of the internal combustion engine.
• ▪ Methane (CH ₄ ) slip from lean-burn gas engines can be oxidized in the motor generator and does not require a costly methane catalyst. In particular, the methane slip can be cleaned here without a catalyst or with less catalyst effort.

Reference List

1

drive arrangement

2

Mobile

3

first conversion engine

4

first tank

5

compressor

6

exhaust outlet

7

second conversion engine

8th

second tank

9

gas inlet

10

expanders (optional)

11

generator

12

electric machine

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• WO 2012002816 A [0027]

Claims (12)

Drive arrangement (1) for a mobile (2) with a first thermal conversion engine (3) for generating a first drive torque for the mobile (2), the first conversion engine (3) having an exhaust gas outlet (6) for discharging exhaust gas from the first conversion engine (3), with a second thermal conversion engine (7), the second conversion engine (7) having a gas inlet (9), characterized in that the exhaust gas outlet (6) is fluidically connected to the gas inlet (9), so that the second conversion engine (7) thermally converts the exhaust gas from the first conversion engine (3). Drive arrangement (1) after claim 1 , characterized in that the second conversion engine (7) has a fuel supply for supplying ammonia or a precursor of ammonia. Drive arrangement (1) according to one of Claims 1 or 2 , characterized by a generator (11), wherein the generator (11) with the second conversion motor (7) is drivingly coupled to convert the mechanical energy from the second conversion motor (7) into electrical energy. Drive arrangement (1) after claim 3 , characterized in that the second conversion engine (7) is drivingly coupled exclusively to the generator (11), so that the entire mechanical energy of the second conversion engine (7) in the generator (11) conducted. Drive arrangement (1) according to one of the preceding claims, characterized in that the second conversion engine (7) is designed as a two-stroke engine. Drive arrangement (1) according to one of the preceding claims 3 until 5 , characterized in that the second conversion motor (7) is designed as a spherical motor, the spherical motor having a housing with a spherical housing interior, a rotor being arranged in the housing interior, a stator section of the generator (11) being connected to the rotor and/or is arranged in the interior of the housing. Drive arrangement (1) according to one of the preceding claims, characterized by an electric machine (12) for generating a second drive torque for the mobile (2), the electric machine (12) being fed directly and/or indirectly via the generator (11) or is fed. Drive arrangement (1) according to one of the preceding claims, characterized in that the first conversion engine (3) has a fuel supply with a fossil fuel and/or is designed as a diesel or petrol or gas engine. Drive arrangement (1) according to one of the preceding claims, characterized in that the first conversion engine (3) has a fuel supply with a regenerative fuel and / or is designed as a hydrogen e-fuel engine. Mobile (2), characterized by a drive arrangement (1) according to one of the preceding claims. Mobile (2) after claim 10 , characterized in that the mobile as a vehicle, boat, aircraft, etc. is formed. Method for exhaust gas purification in the drive arrangement (1) according to one of Claims 1 until 9 and / or in the mobile (2) according to one of Claims 10 or 11 wherein exhaust gases are generated in the first conversion engine (3) and the exhaust gases are thermally converted in the second conversion engine (7).

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