DE102009037876A1 - Internal combustion engine and method for operating this - Google Patents

Abstract

The method involves removing the exhaust gas (16) from an exhaust-outlet (18) of an internal combustion engine. The exhaust gas is recirculated in a fresh air duct (12) of the internal combustion engine. The exhaust gas-fuel-mixture for combustion is ignited downstream of the introduced fuel and upstream of the recirculated exhaust gas. An independent claim is also included for an internal combustion engine with an ignition device.

Description

The The invention relates to a method for operating an internal combustion engine, wherein exhaust gas taken from an exhaust line of the internal combustion engine and back into a fresh air train of the internal combustion engine is guided, wherein in an exhaust gas mass flow in the exhaust system the internal combustion engine is introduced fuel and wherein the recirculated exhaust gas downstream of the introduction of the Fuel is taken into the exhaust gas from the exhaust line, according to the The preamble of claim 1. The invention further relates an internal combustion engine with a fresh air line, an exhaust line, a arranged in the exhaust line device for introducing fuel an exhaust stream in the exhaust line, a sampling point for Removal of exhaust gas from the exhaust system and one with the sampling point for exhaust gas fluidly connected exhaust gas recirculation line (EGR line) for returning exhaust gas in the Fresh air line, according to the preamble of claim 8th.

at turbocharged engines, especially in supercharged diesel engines, is the time course of the power output after a target load request dependent on the boost pressure build-up. In the long run this The loader design, the volumes in the exhaust gas and charge air system have the same procedure and the exhaust gas enthalpy convertible in the turbine (essentially Exhaust gas mass flow and exhaust gas temperature) influence. It is already known the exhaust enthalpy, for example, by post injection in combination with the turbine upstream catalysts, by post combustion of fuel introduced into the exhaust system or by combustion a fuel-air mixture with subsequent feed in to increase the exhaust system upstream of the turbine.

It For example, is known for afterburning the fuel in to introduce the exhaust system in the exhaust full flow. This approach is to be assessed as relatively unfavorable, in particular at high exhaust gas mass flows to reach more flammable Conditions high fuel minimum masses must be injected. Thus, the "burner" performance increases strongly At the same time, however, HC emissions also increase Partial and unburned fuel components.

From the DE 196 51 497 C1 It is known to introduce the fuel into a partial exhaust gas flow, so that on the one hand, the minimum fuel quantity to achieve a combustible mixture decreases and on the other hand, the HC emissions also decrease due to the more favorable burning properties in the partial flow.

From the generic DE 10 2004 013 232 A1 a method and a device for operating an internal combustion engine with exhaust gas recirculation is known, wherein upstream of a catalyst fuel is injected into an exhaust gas mass flow of an exhaust system. The injected, additional amount of fuel is reacted together with unburned exhaust components in the close-coupled catalyst. As a result, the catalyst reaches its operating temperature in a short time. Furthermore, an increased exhaust gas mass flow with a relatively high temperature and thus a high exhaust gas energy is already generated in the cold start, with which a turbine of an exhaust gas turbocharger following in the exhaust system downstream of the catalyst is acted upon. This supports a rapid response of the exhaust gas turbocharger with a correspondingly rapid torque build-up of the internal combustion engine at a load request at low speeds.

Of the Invention is based on the object, a method and an apparatus the o. g. Type with regard to exhaust gas recirculation and the response of the torque output upon load request to improve.

These The object is achieved by a method the o. g. Art having the features characterized in claim 1 and by an internal combustion engine of the o. g. Type marked with the claim 8 Characteristics solved. Advantageous embodiments of the invention are described in the further claims.

at a method of o. Art it is provided according to the invention, that downstream of the introduction of fuel and upstream of the removal the recirculated exhaust gas, the exhaust gas-fuel mixture is ignited for combustion.

This has the advantage that by recycling post-combusted, hot exhaust a deposit formation in an exhaust gas recirculation line and in particular in a cooler for recycled Exhaust (EGR cooler) in the exhaust gas recirculation line the internal combustion engine is effectively reduced.

A high load of combustion chambers of the internal combustion engine due high density of the combustion air supplied exhaust gas achieved by the fact that the recirculated exhaust gas cooled prior to introduction into the combustion air line becomes.

Characterized in that the exhaust gas is supplied downstream of the removal of the recirculated exhaust gas to a turbine of an exhaust gas turbocharger, this turbine is supported by the energy of the introduced and ignited fuel, so that after a load request to the internal combustion engine, even at low speeds a delay-free and faster torque build-up internal combustion machine results.

Thereby, that upstream of the introduction of the fuel, the exhaust gas in at least two exhaust gas streams is divided, the introduction of the fuel takes place in at least one partial exhaust gas stream, is required to reach a combustible mixture Fuel consumption is reduced and HC emissions due to more favorable Burning properties reduced in the exhaust gas partial stream.

a particularly high effect in terms of lowering the required Fuel quantity and the reduction of HC emissions can be achieved in that dividing the exhaust gas into exhaust partial streams such that the partial exhaust gas stream, introduced into the fuel is, 3% to 90%, in particular 20% to 30%, of the total exhaust gas flow corresponds.

A Repatriation solely by due the ignition of the fuel-exhaust mixture heated Exhaust gas is achieved in that at least two, in particular all, Exhaust partial streams downstream of the ignition of the exhaust gas-fuel mixture be merged again, taking the withdrawn Exhaust gases upstream of the merger of partial exhaust gas streams he follows.

A Serving the turbine achieved with a high exhaust gas mass flow one in that the merging of exhaust gas streams upstream the turbine is done.

at a device of o. g. Art it is provided according to the invention, that in the exhaust line downstream of the device for introducing Fuel in the exhaust stream and upstream of the sampling point for recirculated exhaust gas an ignition device for Igniting a combustion of the introduced fuel is arranged.

This has the advantage that by recycling post-combusted, hot exhaust gas a deposit formation in the EGR line and in particular in a cooler arranged in the EGR line for recirculated exhaust gas (EGR cooler) effective is reduced.

To the Cooling of the recirculated exhaust gas is in the EGR line a cooler for the recirculated exhaust gas (EGR cooler) arranged.

Thereby, that in the exhaust line downstream of the sampling point for recirculated exhaust gas a turbine of an exhaust gas turbocharger is arranged, this turbine is brought in by the energy of the and ignited fuel, so that after a load request to the internal combustion engine even at low Speeds a delay-free and faster torque build-up the internal combustion engine results.

Thereby, that upstream of the device for introducing fuel the Exhaust line in at least two exhaust gas strands such shared is that the exhaust line, the exhaust gas in at least two exhaust gas streams leads, wherein the device for introducing fuel is arranged in at least one exhaust pipe section, which is the Reaching a combustible mixture required amount of fuel lowered and become HC emissions due to favorable burning properties reduced in the exhaust gas partial stream.

a particularly high effect in terms of lowering the required Fuel quantity and the reduction of HC emissions can be achieved in that the exhaust partial strands are designed in such a way that the partial exhaust gas flow, which in the exhaust pipe section with the Device for introducing fuel flows, 3% to 90%, in particular 20% to 30%, of the total exhaust gas flow corresponds.

A Repatriation solely by due the ignition of the fuel-exhaust mixture heated Exhaust gas is achieved in that the exhaust gas train is formed in such a way is that at least two, in particular all, exhaust gas strands downstream the device for igniting the exhaust gas-fuel mixture reunite, with the sampling point for the removal of exhaust gas upstream of the union of at least two exhaust strands is arranged in the exhaust manifold, in which the ignition device is arranged.

The The invention will be explained in more detail below with reference to the drawing explained. This shows in the only Fig. A preferred Embodiment of an inventive Internal combustion engine in a schematic representation.

The illustrated in the single FIGURE, preferred embodiment of an internal combustion engine according to the invention comprises working cylinder 10 coming from a fresh air line 12 with combustion air 14 be supplied and from which exhaust gases 16 via an exhaust system 18 be derived. In the fresh air line 12 is a compressor 20 an exhaust gas turbocharger 22 and a charge air cooler 24 arranged. In the exhaust system 18 is a turbine 26 the exhaust gas turbocharger 22 as well as a bypass line 28 with a waste gate 30 for bypassing exhaust gas 16 at the turbine 26 arranged.

The exhaust system 18 is formed such that this in a first exhaust pipe section 32 and a second exhaust manifold 34 splits, wherein in the first exhaust pipe section 32 a first partial exhaust stream 36 and in the second exhaust manifold 34 a second partial exhaust gas stream 38 flows. In the first Partial exhaust train 32 is a sampling point 40 for exhaust 16 of the first partial exhaust stream 36 educated. With this sampling point 40 is fluid conducting an exhaust gas recirculation line 42 (EGR pipe) connected to the exhaust 44 in the fresh air line 12 downstream of the intercooler 24 returns (recirculated exhaust 44 ), so that the working cylinders 10 a combustion air-exhaust gas mixture 46 is forwarded. In the AGR line 42 is a cooler 48 (EGR cooler) for the recirculated exhaust gas 44 and an exhaust gas recirculation valve 50 (EGR valve) arranged.

In the first exhaust pipe section 32 is a device 52 for supplying fuel into the first partial exhaust gas stream 36 the exhaust gas 16 arranged. Downstream of this device 52 is an ignition device 54 for igniting combustion of the introduced fuel in the exhaust gas 16 or in the exhaust gas partial stream 36 , By the arrangement shown, only such exhaust gas is substantially 16 via the EGR line 42 to the fresh air line 12 recycled, which was heated by the combustion of the introduced fuel. As a result, a formation of deposits in the EGR cooler 48 effectively reduced. The portion of the first partial exhaust stream 36 who does not have the EGR line 42 is led back, is at a reunion of the first exhaust section 32 and the second exhaust pipe string 34 the second partial exhaust gas stream 38 admixed, leaving a total heated exhaust 16 the turbine 26 is supplied. This stands for the turbine 26 more exhaust enthalpy for the charging work available and it results in particular at low speeds after a load request a faster torque build-up of the internal combustion engine.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• - DE 19651497 C1 [0004]
• DE 102004013232 A1 [0005]

Claims (14)

Method for operating an internal combustion engine, wherein exhaust gas is removed from an exhaust line of the internal combustion engine and fed back into a fresh air train of the internal combustion engine, wherein in an exhaust gas mass flow in the exhaust line of the internal combustion engine fuel is introduced and wherein the recirculated exhaust gas downstream of the introduction of the fuel into the exhaust gas from the Exhaust line is taken, characterized in that downstream of the introduction of fuel and upstream of the removal of the recirculated exhaust gas, the exhaust gas-fuel mixture is ignited for combustion. Method according to claim 1, characterized in that that the recirculated exhaust gas before the introduction is cooled in the combustion air line. Method according to at least one of the preceding Claims, characterized in that the exhaust downstream the removal of the recirculated exhaust gas of a turbine an exhaust gas turbocharger is supplied. Method according to at least one of the preceding Claims, characterized in that upstream of the introduction of the fuel, the exhaust gas in at least two partial exhaust gas streams is split, the introduction of the fuel in at least a partial exhaust gas flow takes place. Method according to claim 4, characterized in that that dividing the exhaust gas into exhaust partial streams in such a way takes place that the partial exhaust gas stream, in which introduced the fuel is, 3% to 90%, in particular 20% to 30%, of the total exhaust gas flow equivalent. Method according to claim 4 or 5, characterized that at least two, in particular all, partial exhaust gas streams downstream of the ignition of the exhaust gas fuel mixture again be merged, with the removal of the recirculated exhaust gas upstream of the merging of exhaust gas streams he follows. The method of claim 3 and at least one of Claims 4 to 6, characterized in that the merge of exhaust gas streams upstream of the turbine takes place. Internal combustion engine with a fresh air line ( 12 ), an exhaust gas line ( 18 ), one in the exhaust system ( 18 ) arranged device ( 52 ) for introducing fuel into an exhaust stream in the exhaust line ( 18 ), a sampling point ( 40 ) for the removal of exhaust gas ( 16 ) from the exhaust gas line ( 18 ) and one with the sampling point ( 40 ) for exhaust gas ( 16 ) fluid-conducting connected exhaust gas recirculation line ( 42 ) (EGR line) for recirculating exhaust gas ( 44 ) in the fresh air line ( 12 ), characterized in that in the exhaust line ( 18 ) downstream of the device ( 52 ) for introducing fuel into the exhaust stream and upstream of the extraction point ( 40 ) for recirculated exhaust gas ( 44 ) an ignition device ( 54 ) is arranged to ignite a combustion of the introduced fuel. Internal combustion engine according to claim 8, characterized in that in the EGR line ( 42 ) a cooler ( 48 ) for the recirculated exhaust gas ( 44 ) (EGR cooler) is arranged. Internal combustion engine according to at least one of claims 8 or 9, characterized in that in the exhaust system ( 18 ) downstream of the sampling point ( 40 ) for recirculated exhaust gas ( 40 ) a turbine ( 26 ) of an exhaust gas turbocharger ( 22 ) is arranged. Internal combustion engine according to at least one of claims 8 to 10, characterized in that upstream of the device ( 52 ) for introducing fuel of the exhaust gas line ( 18 ) in at least two exhaust partial strands ( 32 . 34 ) is divided so that the exhaust line ( 18 ) the exhaust gas ( 16 ) in at least two partial exhaust gas streams ( 36 . 38 ), the device ( 52 ) for introducing fuel into at least one exhaust sub-string ( 32 ) is arranged. Internal combustion engine according to claim 11, characterized in that the ignition device ( 54 ) in the exhaust pipe section ( 32 ) in which the device ( 52 ) is arranged for introducing fuel. Internal combustion engine according to claim 11 or 12, characterized in that the exhaust partial strands ( 32 . 34 ) are formed such that the exhaust gas partial flow ( 36 ), which in the exhaust section ( 32 ) with the device ( 52 ) for introducing fuel flows, 3% to 90%, in particular 20% to 30%, of the total exhaust gas flow corresponds. Internal combustion engine according to at least one of claims 11 to 13, characterized in that the exhaust gas line ( 18 ) is formed such that at least two, in particular all, exhaust partial strands ( 32 . 34 ) downstream of the device ( 54 ) merge to ignite the exhaust gas-fuel mixture, wherein the sampling point ( 40 ) for the removal of exhaust gas ( 16 ) upstream of the union of at least two exhaust gas strands ( 32 . 34 ) in the exhaust pipe section ( 32 ) is arranged, in which the ignition device ( 54 ) is arranged.

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