DE10240977A1 - Method for operating an internal combustion engine and internal combustion engine itself - Google Patents

Abstract

Method for operating an internal combustion engine, in particular for a motor vehicle, in particular with a direct fuel injection system, comprising an exhaust system with at least one catalytic converter, wherein at least one of the catalytic converters is provided for heating, the internal combustion engine cyclically in a lean mode with lambda> 1 in order to store the oxygen in the at least one catalytic converter to fill up, and to operate in a rich operation with lambda <1, in order to heat up the fuel components in the at least one catalyst by the heat of reaction of a reaction of unburned fuel components, characterized in that first of all by a lambda jump the oxygen storage capacity of each or one Group of catalysts is determined and on the determined respective oxygen storage capacity of the or the catalyst an oxygen-related lower calorific value and taking into account an exhaust gas lambda and an exhaust gas mass flow the energy input and thus a temperature is determined in at least one catalytic converter, whereby regulation and control of the heating of the catalytic converter or catalytic converters is carried out via the setting of the rich and / or lean phases.

Description

The invention relates to a method for operating an internal combustion engine, in particular with a direct fuel injection system or intake manifold injection, comprising an exhaust system with at least a catalyst, wherein for heating at least one of the catalysts is provided, the internal combustion engine cyclically in a lean operation with λ> 1 around the oxygen storage fill up the at least one catalyst and in a rich operation to operate with λ <1, to by a heat of reaction the reaction of unburned fuel components with oxygen in the at least one catalyst to heat it up.

Such methods of operation of internal combustion engines, in particular for motor vehicles, are known. Especially in vehicles with gasoline direct injection it is known that the fuel is in homogeneous operation during the Intake phase or in a shift operation during the compression phase is injected into the combustion chamber of the internal combustion engine. The homogeneous operation is preferably for the Full load operation of the internal combustion engine is provided during the Shift operation for idle or part-load operation is suitable. For example dependent on of a requested torque is such a direct injection Internal combustion engine switched between the operating modes. Shift work serves among other things to minimize fuel consumption and thus to Minimization of exhaust gases.

During lean operation of an internal combustion engine is always an excess of oxygen present in the exhaust system (λ> 1). For this reason can Nitrogen oxides (NOx) contained in the exhaust gases during the Lean operation of the internal combustion engine is not in the 3-way catalytic converter be removed from the exhaust gas. To release such nitrogen oxides to prevent the environment, it is therefore intended to in catch a NOx storage catalyst. Such an exhaust system, in which a 3-way catalytic converter close to the engine and downstream a NOx storage catalytic converter in the exhaust system are used is known from the prior art. In the The catalysts used in engine technology have a limited lambda range, in which they work, often only a limited temperature operating window. These operating windows are above out for the 3-way catalyst and the NOx storage catalyst different. During the 3-way catalytic converter Reduce pollutant components over a large temperature window and can oxidize, this is the temperature range for the NOx storage catalytic converter limited. An exhaust gas cleaning system is therefore usually designed so that both catalysts for wide engine operating areas work in the operating temperature window. One of the catalysts threatens to fall below its lower operating temperature are heating measures necessary. It can doing heating measures for one or for several catalysts are required.

In addition, NOx storage catalysts have to be desulfurized periodically. In addition to their affinity for NOx, the active centers of the NOx storage catalysts also have a high affinity for sulfur oxides. These also arise during the combustion of the fuel and primarily occupy the active centers of the storage catalytic converter. The resulting sulfates are so thermally stable that they are not released in normal storage operations. As a result, the storage capacity of the catalyst for nitrogen oxides decreases with increasing sulfur loading. It was found that at an elevated temperature in the catalyst above 600 ° C and under simultaneously reducing conditions (λ <1) or alternating λ around 1, these are no longer thermodynamically stable and as hydrogen sulfide (H ₂ S) and as sulfur dioxide (SO ₂ ) are released. In order to maintain or restore the storage capacity and thereby regenerate the catalytic converter, the storage catalytic converter must be operated briefly in bold at elevated temperature at certain intervals. To do this, the storage catalytic converter must be heated up to 650 ° C while driving.

There have been a number since then of concepts for heating catalysts.

For example, it is known to generate hot engine exhaust gas in the exhaust valve, for example by means of late ignition or post-injection in the case of lean combustion, as is the case, for example, in EP 1 004 762 A1 is described. If only the NOx storage catalytic converter located downstream in the exhaust system is to be heated, the 3-way catalytic converter located upstream and thus closer to the engine is unnecessarily heated. This leads to increased fuel consumption; In addition, the heat losses on the way to the NOx storage catalytic converter are very high due to the design of the exhaust system. In extreme cases of desulfurization, the maximum permissible temperature of the upstream 3-way catalytic converter can even make it impossible to reach the required temperature in the NOx storage catalytic converter. Alternatively, it is possible to generate unburned hydrocarbons, as well as carbon monoxide and hydrogen by a rich engine operation. These oxidizable exhaust gas components are converted in the NOx storage catalytic converter with the help of the oxygen stored there, releasing heat. A corresponding heating method is described, for example, in WO 98/46868. This makes heating up very efficient possible because the heating measures work without major previous heat losses in the NOx storage catalytic converter, while upstream exhaust gas-carrying components such as exhaust valve, exhaust manifold and pre-catalytic converter are not or only to a small extent thermally stressed. There are essentially three possibilities for such a chemical heating of a storage catalytic converter.

• - With a Y exhaust system, the individual cylinders can be operated rich or lean in banks. If the NOx storage catalytic converter is not in place until the Y merging and a good mixing of the two exhaust gas flows is ensured, it can be heated up in this way. Such a method discloses, for example DE 195 22 165 C2 ,
• - Furthermore, it can be provided to operate the engine rich in total while air is additionally introduced in front of the NO _x storage catalytic converter. Such a method describes, for example DE 197 47 222 C1 ,
• - Finally, rich and lean exhaust gas can be alternately generated, which is disclosed for example in WO 98/46868. The oxygen storage capacity of the catalysts is used. The oxygen reservoir is filled in the lean phase, whereas the oxygen reservoir of the catalyst is used up in the fat phase. Through the reaction with the exhaust gas components hydrocarbon, carbon monoxide and hydrogen, the calorific value of these substances is released and the NO _x storage catalytic converter is thus heated. This last method is independent of the design or additional components, such as the conveyance of additional air by a pump.

The invention is based on the latter Procedure on.

Has such a method doing about it addition the advantage that over the adaptation of the frequency and the amplitude of the fat / lean jumps or Phases the entered amount of heat between pre-catalytic converter and NOx storage catalytic converter can be moved within certain limits; in the borderline case it can even the entire heating capacity is shifted into the pre-catalytic converter.

Conventional motor vehicles with a gasoline engine with intake manifold injection usually do not have Storage catalyst for Nitrogen oxides. However, you have one or more 3-way catalysts, who also about a changing exhaust gas lambda can be heated within certain limits can, like this B. may be necessary in the cold start phase.

For the implementation of surveillance and diagnostic systems it is necessary to monitor the catalyst temperature preferably to be able to set exactly firstly, a complete one Desulfurization to achieve NOx storage catalysts and thus one if possible long service life of the catalysts and secondly overheating e.g. to avoid the upstream 3-way catalytic converter.

For cost reasons and for reasons of Installation space is usually not a direct measurement of the temperatures in the Catalysts possible. It is therefore state of the art that temperatures are determined using coordinated calculation models in an engine control unit, as is intended for direct petrol injectors. The Temperature profiles can are modeled using temperature models.

It is therefore an object of the invention an improved method for operating an internal combustion engine, to provide in particular for heating a catalyst with the temperature in at least one of the catalysts in a simple manner can be determined.

The task is accomplished through a process of the type mentioned in the invention solved in that first by a jump in lambda the oxygen storage capacity of each individual or a group of catalysts is determined and over the determined respective oxygen storage capacity of the catalyst or catalysts a heat input considering a lower calorific value and an exhaust gas mass flow, the energy input and thus a temperature in at least one catalyst is determined is, whereby a regulation and control of the heating of the or Catalysts over the adjustment of the fat and / or lean phases is carried out.

As a measurement in a motor control A motor vehicle engine usually has a value for the ratio of oxygen to stoichiometric relationship (λ) before, so the ratio of the available standing oxygen to the required Oxygen. From this size you can in connection with the mass flow of exhaust gas calculated in the engine control unit and the oxygen stores present in the catalysts Energy input and thus the temperature with changing exhaust gas lambda determine.

It can be provided that the oxygen storage capacity is determined for each individual catalyst in the case of a plurality of catalysts. It is provided here that the engine control unit first triggers a jump in lambda and the oxygen storage capacity of the individual catalytic converters is determined via a determination of the oxygen storage capacity carried out in a conventional manner. For this purpose, in addition to a lambda probe at the outlet after the catalysts, there may be a probe between the pre-catalyst, for example the 3-way catalyst and the second catalyst, namely for example the NOx storage catalytic converter, because otherwise only the entire oxygen storage at the end of the main catalytic converter can be determined.

Such an oxygen storage determination is also carried out on catalysts, for example, for diagnostic purposes.

The oxygen storage of the catalysts is used as a parameter for the maximum energy that can be released during the fat phase. The releasable energy during the lean phases can be neglected due to its small size. The unburned engine exhaust gases entered into the catalytic converter react exothermically with the oxygen in the catalytic converter, so that heat is released. This means that the unburned fuel components are converted with the oxygen storage and converted into heat, which is used to heat up the catalysts. With the knowledge of the chemical energy entered, the heating of the catalysts can be calculated. The following oxidation reactions are used to heat up the catalyst. For simplification, CH _{4 is used} as the basis for the calculation of the hydrocarbons:

These values result in the lower one Calorific value (at the temperature level present in the catalysts) must be used to calculate the catalyst temperatures.

If you normalize the sizes to oxygen, you get:
CO: + 25.12 MJ / m ³ O ₂
H ₂ : + 21, 60 MJ / m ³ O ₂
CH ₄ : + 18.00 MJ / m ³ O ₂
respectively.:
CO: + 17.58 J / mg O ₂
H ₂ : + 15.12 J / mg O ₂
CH ₄ : + 12, 60 J / mg O ₂

The composition of the calorific value Components of an engine exhaust in rich engine operation, that is, at λ <1 essentially represents is a function of lambda.

The carbon monoxide content increases starting from λ = 1 almost linear into the rich area on. The content of Hz also increases linearly, with the increase but only about a half as big slope like that of CO. This leads to a shift the exhaust gas composition with falling lambda towards CO.

The hydrocarbon loading of the On the other hand, exhaust gas does not rise so much, but has one slight increase.

The shift in the composition of the exhaust gas can also exist between the catalysts, since a shift in the composition through the pre-catalyst due to the water gas equilibrium (CO + H ₂ O ⇒ H ₂ + CO ₂ ) takes place, the water gas equilibrium reaction being determined by the temperature and preferably taking place in the hot catalyst at T> 400 ° C.

However, it was found that despite the change in the composition of the calorific value-carrying components with the lambda (to a considerable extent), the specific calorific value based on the size of the oxygen store remains approximately constant, namely at approximately 16000 J / g O ₂ . This specific calorific value is only slightly influenced by the displacement of the components due to the water gas balance.

The heating output is the result out

According to the invention, it is therefore very easy and independent of the lambda set and therefore also independent of the set exhaust gas composition via the oxygen store in the catalyst Determine the energy input in the fat phase, from which the temperature in the catalytic converter is then calculated.

The possible achievable calorific value depends on this on the question of whether the oxygen storage is fully used becomes. Finds only a partial utilization of the oxygen storage in the catalytic converter, the energy input is reduced accordingly. So the value for is halved the energy input, for example, with only half the utilization of the Oxygen reservoir.

As already stated, the oxygen storage capacity an exhaust system using the known lambda jump method determine. To now for a system made up of several catalysts which inputs energy into each To determine catalysts, the entire system has to be converted into pure individual systems. In this case, only partial use of the oxygen storage can of the second catalyst are present, since it is primarily the oxygen store of the first catalyst is emptied before emptying the second Catalyst begins. The first oxygen storage is therefore always almost complete used before the second is used.

Particularly advantageous in the invention it is that by the procedure described, simple Way a calculation of the heating of catalysts in the changing fat-lean operation available stands, the method particularly and independently of is the exhaust gas composition.

The control variables can namely the Oxygen storage of the catalysts, the exhaust gas lambda and the exhaust gas mass flow can be taken from the data of the engine control, which is usually by default in one Motor vehicle with direct fuel injection or intake manifold injection is provided. Across from other ways to model the temperatures of the catalysts inventive method the advantage that the maintenance effort is significantly less, which pays off in a reduction in application costs. Furthermore is the computing effort and thus the necessary processor performance reduced with such a simplified modeling.

The invention further includes a Computer program for implementation of the method, wherein the computer program on a memory, in particular a read-only memory or a flash memory.

Furthermore, the procedure concerns a control and / or regulating device for operating an internal combustion engine, in particular with direct fuel injection, which comprises a memory on which a computer program of the above described type stored and executable to execute a Method of the type described above. The tax and / or regulator is part or coupled to the engine control and receives the necessary Data such as exhaust gas mass flow as well as exhaust gas lambda and oxygen storage capacity from the Motor control. Finally the invention also includes an internal combustion engine with a combustion chamber, in particular with a direct fuel injection device, via which the fuel enters the combustion chamber with a control and / or regulating device and at least one catalyst, at least one for heating Catalysts the internal combustion engine cyclically in rich and lean phases is operable and after and / or between the catalysts Oxygen sensor is provided for determining an oxygen storage capacity of the or of the catalysts and being over the regulating and / or control device by determining an exhaust gas lambda, an exhaust gas mass flow and the oxygen storage capacity a calorific value and thus an energy input and a temperature can be determined and / or is adjustable. In particular, it can be provided that the internal combustion engine is a gasoline engine with direct petrol injection is one of the catalysts in particular a NOx storage catalyst can.

Such an arrangement is fundamentally also for a Y arrangement of the catalysts (two pre-catalysts and one main catalyst) or guaranteed for a complete two-bank version (one fore and one for each) Main catalyst per bank).

The concept is also applicable when using three or more catalysts. The registered Energy then divides according to the oxygen storage capacity of the Single catalysts.

Basically this way also regulates the heating of catalytic converters in diesel engines become. Here, the submission of the fat gas can either via the Engine itself or over a separate introduction before the catalyst. Prefers However, here is a separate introduction of the fat gas before Catalyst.

Other features, possible applications and advantages of the invention will become apparent from the following description of embodiments of the invention, which are shown in the drawing. Make it up all described or illustrated features on their own or in any combination the subject of the invention regardless of its summary in the claims or their relationship back as well as independent from their formulation or representation in the description or in the drawing.

Show:

1 a schematic representation of an internal combustion engine;

2 a further schematic representation of an exhaust system of an internal combustion engine;

3 a representation of the method according to the invention;

4 a representation of the specific energy as a function of lambda.

In the 1 is an internal combustion engine 1 a motor vehicle shown in which a piston 2 in a cylinder 3 can be moved back and forth. The cylinder 3 is with a combustion chamber 4 provided, among other things, by the piston 2 , an inlet valve 5 and an exhaust valve 6 is limited. With the inlet valve 5 is an intake pipe 7 and with the exhaust valve 6 is an exhaust pipe 8th coupled.

In the area of the intake valve 5 and the exhaust valve 6 protrude an injection valve 9 and a spark plug 10 in the combustion chamber 4 , Via the injector 9 can fuel into the combustion chamber 4 be injected. With the spark plug 10 can the fuel in the combustion chamber 4 be ignited.

In the intake pipe 7 is a movable throttle valve 11 housed over the the intake manifold 7 Air can be supplied. The amount of air supplied depends on the open cross-section of the throttle valve 11 , In the exhaust pipe 8th are catalysts 12 housed, which are used to purify the exhaust gases resulting from the combustion of the fuel.

With the catalysts 12 an internal combustion engine with direct fuel injection is a 3-way catalytic converter 12 '' and a NOx storage catalyst 12 '' , The first catalytic converter is used in shift operation 12 ' for the oxidation of HC / CO. In the second catalyst 12 '' the nitrogen oxides are stored. If the catalyst 12 '' a regeneration cycle is initiated accordingly. Here, the engine is briefly greased (λ <1), so that in the catalytic converter 12 '' the nitrogen oxides are reduced (NOx → N ₂ ).

The catalyst works in homogeneous operation 12 ' as a 3-way catalyst. The catalyst 12 '' can also have certain 3-way catalyst properties to support the catalyst 12 ' exhibit.

Between the catalysts 12 ' and 12 '' is a temperature sensor 13 intended. Alternatively or additionally, is in the exhaust pipe immediately after or before the catalysts 12 a temperature sensor 14 intended.

A control unit 18 is of input signals 19 acted upon, the operating variables of the internal combustion engine measured by sensors 1 represent. The control unit 18 generates output signals 20 , with which the behavior of the internal combustion engine via actuators or actuators 1 can be influenced. Among other things, the control unit 18 provided the operating parameters of the internal combustion engine 1 to control and / or regulate. For this purpose the control unit 18 provided with a microprocessor which has stored a program in a storage medium, in particular in a flash memory, which is suitable for carrying out the aforementioned control and / or regulation.

In a first operating mode, a so-called homogeneous operation of the internal combustion engine 1 , the throttle valve 11 partially open or closed depending on the desired torque. The fuel is from the injector 9 during one by the piston 2 induced suction phase in the combustion chamber 4 injected. By simultaneously over the throttle valve 11 Intake air is swirled around the injected fuel and thus in the combustion chamber 4 essentially evenly distributed. The fuel / air mixture is then compressed during the compression phase and then removed from the spark plug 10 to be ignited. Due to the expansion of the ignited fuel, the piston becomes 2 driven. The torque generated in homogeneous operation depends, among other things, on the position of the throttle valve 11 from. In view of a low pollutant development, the fuel / air mixture is set to lambda equal to one if possible.

In a second operating mode, a so-called stratified operation of the internal combustion engine 1 , the throttle valve 11 wide open. The fuel is from the injector 9 during one by the piston 2 caused compression phase in the combustion chamber 4 injected, locally in the immediate vicinity of the spark plug 10 as well as at a suitable distance before the ignition point. Then using the spark plug 10 the fuel ignites, leaving the piston 2 is driven in the now following work phase by the expansion of the ignited fuel. The resulting torque largely depends on the injected fuel mass in shift operation. The stratified operation is essentially for idling operation and partial load operation of the internal combustion engine 1 intended.

The storage catalytic converter 12 ' absorbs sulfur over time during its continuous loading and unloading with nitrogen oxides. This leads to a limitation of the storage capacity of the storage catalytic converter 12 ' , hereinafter referred to as aging.

In order to counteract the aging due to the sulfur loading and to increase the ability of nitrogen oxides to be stored in the storage catalytic converter again, it is necessary to carry out a significant temperature increase in the form of a catalytic converter heating. For this, the internal combustion engine 1 from alternately operated in rich and lean operation in relatively short time intervals, with the oxygen storage of the individual catalysts being charged in lean operation. The maximum oxygen storage capacity can be determined in a known form using a lambda jump method, the determination using the lambda sensors 22 (LSF or LSU, whereby an LSF probe can also be used instead of the LSU probe) after the individual catalysts 12 ' and 12 '' is made. In the fat phase, the oxygen store is then used again and the oxygen is reacted exothermally with carbon monoxide, hydrogen and hydrocarbons, so that there is an increase in the temperature in the stores in the catalysts 12 ' and 12 " comes, causing a heating, the so-called cat heating. There is no appreciable temperature increase in the lean phases. A temperature of approx. 600 to 650 ° C must be reached in order to clean the NOx storage catalytic converter 12 '' to achieve from the stored sulfur compounds.

To now have a sufficient temperature to achieve and control the fat and lean phases accordingly to be able to make modeling of the temperature is necessary.

For this purpose, as already explained, the oxygen storage capacity of the two catalysts is determined using the lambda jump method 12 ' and 12 '' determined separately. The energy input of each fat-lean cycle can be determined via the oxygen mass entered in the lean phase and the oxygen-related calorific value of the fat gas converted in the fat phase. The oxygen-related calorific value is approximately 16000 J / g O ₂ and is only dependent to a lesser extent on the water gas equilibrium over the first catalytic converter and also only to a lesser extent on the shift in the exhaust gas composition with different lambda. An approximately constant calorific value of 16000 J / g O ₂ and in particular 16300 J / g O _{2 can be} assumed. The oxygen mass determining the energy input can then be determined in the control unit 18 Known quantities of exhaust gas mass flow and lambda are determined, the temperature in the catalytic converters being able to be determined here. In this way it can be determined how the rich and lean phases are to be controlled when the catalyst is heated. The temperature can be raised by the control unit via the temperature sensor during the heating process 18 can be monitored only with difficulty or only in part because the temperature sensors 13 . 14 are usually located behind the first catalyst due to other requirements. In addition, the temperature sensor delivers 13 . 14 no information about how the energy input is distributed over the catalysts. With the control unit 18 this is the engine control. The temperature increase of the catalyst behind the temperature sensors is in the engine control 18 modeled using the calculated chemical energy input.

4 now shows a table in which the specific energy in the exhaust gas above the value 1 / λ is also referred to as the Exhaust Equivalence Ratio (EQR). The graphic shows that the specific energy in the exhaust gas fluctuates only slightly despite the shift in the lambda. The measured values marked with circles and cross lines were determined for a lower mass flow than the dark lines. The mass flow also has only a minor influence on the specific energy in the exhaust gas.

The values were determined on the one hand before the pre-catalytic converter and on the other hand after the pre-catalytic converter, whereby it can be seen that the water gas equilibrium also has no significant influence on the specific energy. Before the pre-catalyst 12 ' it is raw engine exhaust, after the pre-catalyst 12 ' the possible equilibrium has taken place.

In the manner described above, the second catalyst can simply be heated 12 '' be regulated without being exposed to the risk that the temperature required for the respective purpose for the NOx storage catalytic converter 12 '' is not reached or one of the catalysts 12 ' . 12 '' is overheated.

In the following, the procedure shall be based on 3 are explained.

According to 3 as the start of the method, one or several averaging lambda jumps by the engine control 18 be generated. The results measured in this way result in the oxygen storage capacity of the catalytic converter / catalytic converter, also known as OSC (Oxygen-Storage Capacity). This value is in the control unit 18 calculated. The exhaust gas mass flow m and the exhaust gas lambda λ are then determined and also sent to the control and regulating device 18 passed, where m is present as a calculation variable in the control unit and is not measured via a sensor. The engine is then operated with alternating rich and lean phases. The control unit 18 determines the oxygen mass entered in the lean phase from the exhaust gas mass flow m and the exhaust gas lambda λ. This oxygen is converted in the following fat phase. The energy input of the fat phase and the resulting temperature in the catalysts can be determined from the oxygen-related calorific value 12 ' . 12 '' be determined. Measures for controlling the catalyst heating by the control unit can be carried out via the phase length (frequency), the amplitude and the reduction of the lambda 18 to be hit.

Claims (12)

Method for operating an internal combustion engine, in particular for a motor vehicle, in particular with a direct fuel injection system, comprising an exhaust system with at least one catalytic converter, wherein at least one of the catalytic converters is provided for heating, the internal combustion engine cyclically in a lean operation with λ> 1 in order to store the at least one catalytic converter in oxygen fill up and operate in a rich operation with λ <1, in order to heat up the oxygen in the at least one catalyst by the heat of reaction of a reaction of unburned fuel components, characterized in that initially the oxygen storage capacity of each individual or a group is increased by a λ jump is determined by catalysts and, via the determined respective oxygen storage capacity of the catalyst or catalysts, an oxygen-related lower calorific value and taking into account an exhaust gas lambda and an exhaust gas mass flow, the energy Entry and thus a temperature is determined in at least one catalytic converter, whereby regulation and control of the heating of the catalytic converter or catalytic converters is carried out via the setting of the rich and / or lean phases. A method according to claim 1, characterized in that at several catalysts the oxygen storage capacity for each individual is determined. A method according to claim 1 or 2, characterized in that the λ jump and the fat gas input into the catalyst or catalysts is determined using a λ probe becomes. Method according to one of claims 1 to 3, characterized in that the specific calorific value is essentially independent of the set λ and the exhaust gas composition and in particular is approximately 16000 J / g O ₂ . Method according to one of the preceding claims, characterized in that that the temperature in the catalyst is calculated based on the oxygen storage capacity becomes. Computer program, characterized in that the computer program to carry out of the method according to one of the preceding claims is when it runs on a computer. Computer program according to claim 6, characterized in that it on a memory, in particular a read-only memory or a flash memory is stored. Control and / or regulating device for operating an internal combustion engine, in particular with direct fuel injection, which comprises a memory on which a computer program according to a of claims 6 or 7 is saved. Internal combustion engine with a combustion chamber ( 4 ), in particular with a direct fuel injection device, via which the fuel enters the combustion chamber ( 4 ) arrives with a control and / or regulating device ( 18 ) and at least one catalyst ( 12 ), for heating at least one catalyst ( 12 ) the internal combustion engine ( 1 ) can be operated cyclically in rich and lean phases and after and / or between the catalysts ( 12 ' . 12 '' ) an oxygen sensor ( 22 ) is provided for determining an oxygen storage capacity of the catalyst (s) ( 12 ' . 12 '' ) and whereby via the regulating and / or control device ( 18 ) by determining an exhaust gas lambda, an exhaust gas mass flow of the internal combustion engine and the oxygen storage capacity, a calorific value and thus an energy input or a temperature in the catalysts ( 12 ' . 12 '' ) can be determined and thus regulated by adjusting the fat or lean phases. Internal combustion engine according to claim 9, characterized in that the internal combustion engine ( 1 ) is a gasoline engine. Internal combustion engine according to claim 9 or 10, characterized in that one of the catalysts ( 12 ' . 12 '' ) is a NOx storage catalytic converter. Internal combustion engine according to claim 9 to 11, which is a control and / or regulating device ( 18 ) according to claim 8.