DE102021107092A1 - Internal combustion engine with exhaust gas aftertreatment component, heating device and gas delivery device - Google Patents

Abstract

Internal combustion engine with an internal combustion engine (1), a fresh gas line (5) and an exhaust line (8), with a fresh gas compressor (11) in the fresh gas line (5) and an exhaust gas turbine (12) in the exhaust line (8) and, downstream of the exhaust gas turbine (12), an exhaust aftertreatment component with an electric heater (17) are integrated. Between the exhaust gas turbine (12) and the exhaust gas aftertreatment component, a supply line (18) for air opens into the exhaust line (8), the air being able to be conveyed into the exhaust line (8) by means of a gas conveying device (20) that differs from the fresh gas compressor (11).

Description

The invention relates to an internal combustion engine with an internal combustion engine, a fresh gas line and an exhaust line, with a fresh gas compressor being integrated in the fresh gas line and an exhaust gas turbine and, downstream of this, an exhaust gas aftertreatment component with an electric heating device.

The exhaust gas limits that apply to internal combustion engines are becoming increasingly strict. This applies in particular to internal combustion engines that are intended to drive motor vehicles. In order to be able to comply with these emission limit values, it is necessary for the conversion capability of exhaust gas aftertreatment components that are integrated in the exhaust lines of these internal combustion engines to exist as quickly as possible after starting the engine in a cold state (cold start). This requires that the exhaust gas aftertreatment components reach their light-off temperatures (also called light-off temperatures) as quickly as possible after a cold start of the respective internal combustion engine, from which point sufficient effectiveness for the exhaust gas aftertreatment can be assumed.

It is known that exhaust gas aftertreatment components can also be temporarily heated. This can be achieved both by engine measures aimed at achieving relatively high exhaust gas temperatures in a targeted manner and by active heating measures, for example by means of electrical heating devices.

the DE 10 2019 206 085 A1 discloses a method for operating an internal combustion engine with a catalytic converter, which is heated up with the aid of a heating device before a cold start of the internal combustion engine. For this purpose, a fresh air mass flow is heated by the heating device or an exhaust gas mass flow is generated and supplied to the catalytic converter for heating, the heating device being supplied with fresh air by the compressor of an electric turbocharger.

The disadvantage of this method is that the exhaust gas turbine coupled thereto must also be driven in order to convey the fresh air by means of the compressor. As a result, the energy consumption for conveying the fresh air is relatively high. This applies in particular because the driven exhaust gas turbine generates a negative pressure in the section of the exhaust system arranged upstream of it due to the non-operation of the internal combustion engine.

the DE 10 2017 113 366 A1 describes an exhaust aftertreatment system for a spark-ignited internal combustion engine. The internal combustion engine is connected to an exhaust system on the outlet side, with an exhaust gas turbine of an exhaust gas turbocharger, then an electrically heatable three-way catalytic converter, then a four-way catalytic converter and downstream of this another three-way catalytic converter being arranged in the exhaust system in the flow direction of an exhaust gas through the exhaust system. Before starting the internal combustion engine, the electrically heatable three-way catalytic converter and preferably also, by means of a burner, the four-way catalytic converter are heated in order to enable efficient exhaust aftertreatment of the raw emissions from the internal combustion engine as soon as the internal combustion engine is started. A secondary air system is provided on the exhaust system, with which secondary air can be blown into the exhaust ducts of the internal combustion engine. This can also take place while the electrically heatable three-way catalytic converter is being heated before the internal combustion engine is started.

The disadvantage of this procedure is that the secondary air first has to pass through the exhaust gas turbine in order to be able to distribute the thermal energy generated by a heating element of the electrically heatable three-way catalytic converter as a heat transfer medium. Furthermore, blowing secondary air into the exhaust ports of the internal combustion engine that is not in operation can lead to problems if the operation of the internal combustion engine has ended with a valve overlap between the intake and exhaust valves.

the DE 10 2019 110 992 A1 discloses a method for exhaust aftertreatment of an internal combustion engine. For this purpose, the internal combustion engine is connected with its outlet to an exhaust system, in which at least one catalytic converter is arranged, which can be heated with external heating means. The at least one catalytic converter is heated with the external heating means from the moment the internal combustion engine is started, the combustion in the combustion chambers of the internal combustion engine being optimized with regard to the untreated emissions produced during combustion.

The invention is based on the object of avoiding the disadvantages described with regard to electrical heating of an exhaust gas aftertreatment device when the internal combustion engine of an internal combustion engine is not in operation.

This problem is solved in an internal combustion engine according to patent claim 1 . A method for operating such an internal combustion engine is the subject of patent claim 6. Advantageous embodiments of the internal combustion engine according to the invention and preferred embodiments of the method according to the invention are the subject of the further patent claims and result from the following description of the invention.

An internal combustion engine according to the invention comprises at least one internal combustion engine and a fresh gas line for supplying fresh gas to the internal combustion engine, a fresh gas compressor being integrated in the fresh gas line. Furthermore, an internal combustion engine according to the invention comprises an exhaust line for discharging exhaust gas from the internal combustion engine, with an exhaust gas turbine and, downstream (with respect to the flow direction of exhaust gas starting from the internal combustion engine) from the exhaust gas turbine, at least one exhaust gas aftertreatment component with an electric heating device being integrated in the exhaust gas line. The heating device is assigned to the exhaust gas aftertreatment component, so that it can be used to heat the exhaust gas aftertreatment component in a targeted manner if required. For this purpose, the heating device can be integrated into the exhaust gas aftertreatment component in such a way that it directly heats the exhaust gas aftertreatment component. Preferably, however, it is provided that the heating device is integrated into the exhaust line upstream, in particular immediately upstream, of the exhaust gas aftertreatment component, so that heating takes place essentially indirectly, in that a gas flow is first heated by means of the heating device, which then causes the exhaust gas aftertreatment component to be heated.

In order to achieve the most advantageous possible heating of the gas flow, it can preferably be provided that the heating device integrated in the exhaust line has a multiplicity of through-openings for a gas flow to flow through. As a result, a heating device that is as large as possible, in particular that takes up the entire flow cross section of the exhaust line, can be implemented.

According to the invention, a feed line for air opens into the exhaust line between the exhaust gas turbine and the exhaust gas aftertreatment component, the air being able to be conveyed via this feed line into the exhaust line by means of a gas conveying device that differs from the fresh gas compressor. By means of the gas delivery device, the heating device can be put into operation independently of the operation of the internal combustion engine and thus also independently of the exhaust gas of the internal combustion engine flowing through the exhaust line, because the thermal energy released by it can advantageously be distributed by means of a gas flow generated by the gas delivery device. This not only has an advantageous effect with regard to the most uniform possible heating of the exhaust gas aftertreatment component, but also with regard to the performance and/or the service life of the heating device, because operation of the heating device without a gas flow flowing through and/or around it, which absorbs the thermal energy released by the heating device absorbs and dissipates, there could be a thermal overload of the heating device or it could possibly only be operated to a limited extent in terms of heating power in order to avoid such a thermal overload.

By arranging the opening of the supply line for the air in the section of the fresh gas line that is located between the exhaust gas turbine and the exhaust gas aftertreatment component with the associated heating device, it can be avoided that the air conveyed by means of the gas conveying device has to flow through the exhaust gas turbine, which creates a corresponding flow resistance for the flow of air is prevented. In addition, the exhaust gas turbine (as an obstacle) and the sufficient distance between the mouth of the supply line and the combustion engine prevent the air fed into the exhaust system from influencing the pressure conditions at the exhaust valves of the combustion engine to a relevant extent, so that there are also negative effects that would otherwise arise in particular due to existing valve overlaps between the intake and exhaust valves of the non-operating internal combustion engine can be avoided.

Since the heating device can also be operated when the internal combustion engine is not in operation due to the supply of air by means of the gas delivery device, it can advantageously be used to Preheat the cold start of the internal combustion engine in order to ensure that at least the exhaust gas aftertreatment component has already reached its light-off temperature when the internal combustion engine is started up, from which it can be assumed that the exhaust gas aftertreatment is sufficiently effective, or at least reaches it as soon as possible thereafter. Accordingly, a method according to the invention for operating an internal combustion engine provides that the heating device and the gas delivery device are put into operation before the internal combustion engine is started up and in particular before it is cold started.

Since exhaust gas is generated by this when the internal combustion engine is started up and is discharged via the exhaust line, a method according to the invention can also be used be seen that with this commissioning of the internal combustion engine or shortly thereafter at least the operation of the gas delivery device is stopped again because the air flow generated by this for the distribution of the thermal energy generated by the heating device can then no longer be required. The operation of the heating device can also be ended when the internal combustion engine is started up. However, this is preferably only done if the light-off temperature of the exhaust gas aftertreatment components has already been reached when the internal combustion engine is started up.

The heating device and/or the gas delivery device can also advantageously be used and operated during a regeneration operation of the internal combustion engine, in which the exhaust gas aftertreatment component and/or another exhaust gas aftertreatment component integrated into the exhaust system is/are temporarily heated to a temperature required for regeneration. Operation of the gas delivery device can be used in particular to introduce oxygen (as part of air) into exhaust gas that was generated by the internal combustion engine during the regeneration operation and that specifically includes unburned hydrocarbons due to a correspondingly set operation of the internal combustion engine, in order to oxidize the cause unburned hydrocarbons. The thermal energy released in the process is intended to heat the exhaust gas aftertreatment component(s) to the temperature (in each case) required for the regeneration. Alternatively or additionally, the heating device can also be used to reach the corresponding regeneration temperature of the exhaust gas aftertreatment component(s), wherein a flow of air generated by the gas delivery device can additionally ensure an advantageous distribution of the heat energy released.

A use of the heating device and the gas delivery device on the one hand before starting up the internal combustion engine for preheating the exhaust gas aftertreatment component and on the other hand for regenerating the exhaust gas aftertreatment component(s) can be provided independently of one another, so that only one of the two variants has to be implemented within the scope of a method according to the invention . However, both are advantageously implemented (not simultaneously), so that an advantageous dual use can be realized for the heating device and the gas conveying device.

A valve, in particular an actively controllable valve or a passive valve (e.g. a non-return valve), can preferably be integrated into the feed line, as a result of which an overflow of exhaust gas from the exhaust line into the (entire) feed line can be avoided.

According to a preferred embodiment of an internal combustion engine according to the invention, it can be provided that the gas conveying device is or comprises a blower. Such a fan has the advantage of a simple and cost-effective design. In addition, a relatively large gas mass flow can be provided by means of such a blower even with relatively low drive power, which has an advantageous effect with regard to the desired distribution of thermal energy generated by means of the heating device. Due to the arrangement of the mouth of the supply line, via which the flow of air is introduced into the exhaust system by means of the fan, downstream of the exhaust gas turbine, the disadvantage that gas flows with high pressure differences cannot usually be generated by means of a fan does not have a negative effect.

According to a preferred embodiment of an internal combustion engine according to the invention, it can be provided that, upstream of the exhaust gas turbine, a second supply line for air opens into the exhaust system or into one or more outlet ducts of the internal combustion engine, with air being able to be conveyed by means of the gas conveying device, if necessary, via this second supply line. As a result, the same gas conveying device can advantageously be provided for the inventive distribution of thermal energy generated by the heating device and for introducing air upstream of the exhaust gas turbine, which can be used in particular as secondary air. A valve, in particular an actively controllable valve or a passive valve (e.g. a non-return valve) can preferably also be integrated into the second supply line in order to control the conveying of air via this second supply line.

The exhaust gas aftertreatment component of an internal combustion engine according to the invention can preferably comprise a catalytic converter element, in which case the catalytic converter element can particularly preferably be effective as a three-way catalytic converter. By means of such an exhaust gas aftertreatment component, a relatively extensive exhaust gas aftertreatment with regard to several pollutants can be implemented, so that the required heating of such an exhaust gas aftertreatment component by means of the heating device, in particular before a cold start of the internal combustion engine, can have a particularly advantageous effect on the pollutant emission behavior of the internal combustion engine. This applies in particular in combination with the configuration of the internal combustion engine, which is also preferably provided, as spark-ignited and in particular as an Otto engine, so that the internal combustion engine of an internal combustion engine according to the invention comprises at least one ignition device for igniting fuel-oxygen mixtures in at least one combustion chamber, for example based on one or more spark plugs generating ignition sparks.

Alternatively, the internal combustion engine of an internal combustion engine according to the invention can also be a self-igniting internal combustion engine and in particular a diesel engine. There is also the possibility that the internal combustion engine is a combination of a spark-ignited and self-igniting internal combustion engine, for example an internal combustion engine with homogeneous compression ignition. The internal combustion engine of an internal combustion engine according to the invention can be operated both with liquid fuel (i.e. diesel or petrol) and with a gaseous fuel (in particular natural gas, LNG or LPG).

According to a preferred embodiment of an internal combustion engine according to the invention, it can be provided that the gas delivery device can be controlled with regard to the delivery capacity and/or the heating device with regard to the heating capacity, so that the gas delivery device does not only have a single delivery capacity during operation and/or the heating device does not only have a single delivery capacity during operation Heat output during operation and continue, each, can provide zero power when not in operation. As a result, the best possible adaptation of the heating output and/or a distribution of heat energy generated by means of the heating device can be realized by an air flow provided by the gas delivery device.

In particular, it can be realized within the scope of a method according to the invention that the gas conveying device is operated with a conveying capacity that is dependent on the heat output of the heating device, it being particularly preferably provided that the gas conveying device is operated at least with a first, relatively small conveying capacity when the heating device with a first, relatively small heat output is operated, while the gas conveying device is operated with a second, relatively large, possibly an average conveying power when the heating device is operated with a second, relatively large, possibly maximum heat output. The first, relatively small heat output can be present in particular during a heating-up phase of the heating device, in which case, as a result of the first, relatively small flow rate of the gas supply device, a relatively small and, in particular, also relatively slow air mass flow is guided over the heating device, as a result of which the relatively low heat output of this air mass flow is as possible as possible can be easily transferred to the exhaust aftertreatment components. The second, relatively high delivery rate of the gas delivery device, on the other hand, with the second, relatively high heating output of the heating device, can ensure that the relatively high heat output released in the process is dissipated as optimally as possible by the heating device and transferred to the exhaust gas aftertreatment component.

As an alternative or in addition to this, provision can also be made for the gas delivery device to be operated with a lower delivery capacity in comparison to the regeneration mode of the combustion engine before the combustion engine is started up. The relatively high delivery rate during the regeneration operation of the internal combustion engine can be used in particular to generate a pressure of the air to be introduced into the exhaust system via the supply line, which pressure is above the pressure of the exhaust gas flowing through the exhaust system, in order to ensure that the air is introduced into the exhaust system . It can optionally be provided that the gas delivery device is operated at maximum delivery capacity during the regeneration operation of the internal combustion engine.

The preferably provided design of the gas delivery device that can be controlled with regard to the delivery capacity can also advantageously make it possible to design the valve that is also preferably (respectively) integrated into the supply line(s) as a simple and inexpensive passive valve, in particular as a check valve, since an adjustment of the mass flow of the Air can be realized by means of the gas conveying device.

The invention also relates to a motor vehicle, in particular a wheel-based and non-rail-bound motor vehicle (preferably a car or a truck), with an internal combustion engine according to the invention. The internal combustion engine of the internal combustion engine can be provided in particular for the (direct or indirect) provision of the driving power for the motor vehicle.

• 1: eine für die Durchführung eines erfindungsgemäßen Verfahrens geeignete Brennkraftmaschine und
• 2: eine Abgasnachbehandlungseinrichtung der Brennkraftmaschine im Detail.

The invention is explained in more detail below with reference to an exemplary embodiment illustrated in the drawings. The drawings show, each in a simplified representation:

• 1 : an internal combustion engine suitable for carrying out a method according to the invention and
• 2 : an exhaust aftertreatment device of the internal combustion engine in detail.

The one in the 1 Internal combustion engine shown comprises an internal combustion engine 1, which at is designed for example in the form of a reciprocating engine with four cylinder ports 2 arranged in a row. The cylinder openings 2 each delimit a combustion chamber 4 with reciprocating pistons 3 guided therein and a cylinder head. During operation of the internal combustion engine 1 and thus the internal combustion engine, these combustion chambers 4 are supplied with fresh gas via a fresh gas line 5, with the fresh gas being supplied by means of inlet valves 6, which are connected to the individual combustion chambers 4 are assigned is controlled. The fresh gas is exclusively or mainly air that is sucked in from the environment. Exhaust gas is generated during the combustion of mixture quantities consisting of fresh gas and fuel injected directly into combustion chambers 4 via fuel injectors 7 . This exhaust gas is discharged via an exhaust line 8 of the internal combustion engine, the discharge of the exhaust gas from the individual combustion chambers 4 being controlled by means of outlet valves 9 . The quantities of mixture in the combustion chambers 4 are ignited by means of electrical ignition devices 10 which, for example, generate ignition sparks (spark plugs).

The internal combustion engine is supercharged, for which purpose a fresh-gas compressor 11 is integrated into the fresh-gas line 5 . The fresh-gas compressor 11 is part of an exhaust-gas turbocharger, which also includes an exhaust-gas turbine 12 that is integrated into the exhaust-gas line 8 . Exhaust gas that flows through the exhaust gas turbine 12 leads to a rotating drive of a turbine impeller, which is connected to a compressor impeller of the fresh gas compressor 11 via a shaft 13 in a rotationally driving manner, so that the result is that the fresh gas compressor 11 is driven by the exhaust gas turbine 12.

The exhaust gas turbine 12 is arranged upstream (with respect to the flow direction of the exhaust gas) of an exhaust gas aftertreatment device 14 in the exhaust line 8 . The exhaust gas aftertreatment device 14 is intended to remove components of the exhaust gas that represent pollutants from the exhaust gas or to convert them into harmless components.

The exhaust gas aftertreatment device 14 comprises according to 2 as exhaust gas aftertreatment components, for example, a first, relatively small three-way catalytic converter 15, a second (compared to the first three-way catalytic converter 15) relatively large three-way catalytic converter 16 and a particle filter 22. Between the first three-way catalytic converter 15 and the second three-way catalytic converter 16 is a disc-shaped, electric heating device 17 arranged , wherein the heater 17 is directly adjacent to both the first three-way catalyst 15 and the second three-way catalyst 16. The cross-sectional areas of the heating device 17 are essentially the same size as the cross-sectional areas of the three-way catalytic converters 15, 16. The heating device 17 or an electrically heatable heating element thereof forms a large number of through-openings (not visible) in order to enable a gas to flow through. The same applies to the three-way catalytic converters 15, 16, which for this purpose have supporting bodies with defined porosities, these supporting bodies being provided with coatings that act as three-way catalytic converters.

Directly upstream of the first three-way catalytic converter 15, a supply line 18 opens into the exhaust system 8 or into a common housing of the three-way catalytic converters 15, 16 and the heating device 17. If required, air can be conducted into the exhaust system 8 via this supply line, with this air being conveyed downstream of an air filter 19 ( and can be branched off from the fresh gas line 5 upstream of the fresh gas compressor 11). This arrangement of a branch of the supply line 18 has the advantage that branched air has already been cleaned by means of the air filter 19, which can prevent particles from being contained in the air introduced into the exhaust line 8, which could clog the three-way catalytic converters 15,16 .

If necessary, air is introduced into the exhaust line 8 via the feed line 18 by operating a gas conveying device 20 integrated into the feed line 18, which is designed in the form of a blower. Furthermore, a valve 21 can be integrated into the feed line 18 in order to be able to control gas flows via the feed line 18 . The valve 21 can be actively controllable. However, this can also be a passive non-return valve which closes when there is an overpressure on the part of the exhaust line 8 . In this way it can be avoided that exhaust gas is unintentionally routed via the feed line 18 from the exhaust gas line 8 into the fresh gas line 5 . The valve is integrated into the supply line 18 downstream of the gas delivery device 20, thereby preventing the gas delivery device 20 from being subjected to hot exhaust gas when it is not in operation and when there is then usually an overpressure on the side of the exhaust line 8. A thermal overload of the gas delivery device 20 can thereby be avoided.

According to the invention, it is provided that the heating device 17 and the gas delivery device 20 are put into operation before the internal combustion engine 1 is put into operation and in particular before a cold start, as a result of which the second three-way catalytic converter 16 in particular can be preheated. This can ensure that at least the second three-way catalytic converter 16 with the start-up of the internal combustion engine 1 or at least shortly thereafter has already reached its light-off temperature and can thus immediately bring about sufficiently good exhaust gas aftertreatment. The generation of a flow of air by means of the gas delivery device 20 and its supply (via the first three-way catalytic converter 15) to the heating device 17 and then further through the second three-way catalytic converter 16 (and then through the rest of the exhaust system 8) ensures that the from the heating device 17 released thermal energy is distributed as evenly as possible to the second three-way catalytic converter 16 in particular. This distribution of the thermal energy also prevents thermal overloading of the heating device 17, which could result from heat accumulation due to thermal energy generated by the latter itself.

Reference List

1

combustion engine

2

cylinder opening

3

reciprocating

4

combustion chamber

5

fresh gas line

6

intake valve

7

fuel injector

8th

exhaust line

9

outlet valve

10

ignition device

11

fresh gas compressor

12

exhaust turbine

13

Wave

14

exhaust aftertreatment device

15

first three-way catalytic converter

16

second three-way catalytic converter

17

heating device

18

supply line

19

air filter

20

gas conveying device

21

Valve

22

particle filter

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

• DE 102019206085 A1 [0004]
• DE 102017113366 A1 [0006]
• DE 102019110992 A1 [0008]

Claims (10)

Internal combustion engine with an internal combustion engine (1), a fresh gas line (5) and an exhaust line (8), with a fresh gas compressor (11) in the fresh gas line (5) and an exhaust gas turbine (12) in the exhaust line (8) and downstream of the exhaust gas turbine (12), an exhaust gas aftertreatment component are integrated with an electrical heating device (17), characterized in that between the exhaust gas turbine (12) and the exhaust gas aftertreatment component a supply line (18) for air opens into the exhaust line (8), the air being from the fresh gas compressor (11) different gas delivery device (20) via the feed line (18) in the exhaust system (8) can be promoted. Internal combustion engine according claim 1 , characterized in that the heating device (17) is arranged upstream of the exhaust gas after-treatment component and has through-openings for a gas flow to flow through. Internal combustion engine according to one of the preceding claims, characterized in that the gas conveying device (20) is or comprises a blower. Internal combustion engine according to one of the preceding claims, characterized in that the internal combustion engine (1) comprises an ignition device (10) for igniting fuel-oxygen mixtures in at least one combustion chamber (4). Internal combustion engine according to one of the preceding claims, characterized in that the gas delivery device (20) can be controlled with regard to delivery capacity and/or the heating device (17) with regard to heating capacity. Method for operating an internal combustion engine according to one of the preceding claims, characterized in that the heating device (17) and the gas delivery device (20) are put into operation before the internal combustion engine (1) is started up. procedure according to claim 6 , characterized in that the operation of the gas delivery device (20) and / or the heating device (17) is terminated with the commissioning of the internal combustion engine (1). procedure according to claim 6 or 7 , characterized in that the heating device (17) and / or the gas delivery device (20) during a regeneration operation of the internal combustion engine (1), in which the exhaust gas aftertreatment component and / or another exhaust gas aftertreatment component is / are temporarily heated to a temperature required for a regeneration, operate. procedure according to claim 8 , characterized in that the internal combustion engine (1) is operated during the regeneration operation in such a way that the exhaust gas generated by this specifically includes unburned hydrocarbons. Method according to one of Claims 6 until 9 for operating an internal combustion engine according to claim 5 , characterized in that - the gas delivery device (20) is operated with a delivery capacity that is dependent on the heat output of the heating device (17) and/or - the gas delivery device (20) before the internal combustion engine (1) is started up with a lower delivery capacity compared to the Regeneration operation of the internal combustion engine (1) is operated.

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