DE102020201433A1 - Internal combustion engine with increased gas throughput in overrun mode - Google Patents

Abstract

An internal combustion engine 1 comprises a 4-stroke internal combustion engine 3, which has at least one combustion chamber 6, in which a reciprocating piston 5 is cyclically moved between a top dead center (OT) and a bottom dead center (BDC) during operation of the internal combustion engine 1 and at least an inlet valve 20 and an outlet valve 21 are assigned, - a fresh gas line 7, in which a fresh gas compressor 9 of an exhaust gas turbocharger and, downstream of the fresh gas compressor 9, a throttle valve 11 are integrated, and - an exhaust gas line 13, in which an exhaust gas turbine 12 of the exhaust gas turbocharger and downstream of the exhaust gas turbine 12, an exhaust gas aftertreatment device 14 is integrated, wherein the exhaust gas aftertreatment device 14 can be bypassed if necessary by means of an exhaust gas aftertreatment bypass 17, which goes off between the exhaust gas turbine 12 and the exhaust gas aftertreatment device 14 from the exhaust system 13, and wherein the throttle valve 11 is in a partially or fully is set to the constantly open position and - a flow through the exhaust gas aftertreatment bypass 17 is enabled and - the inlet valve 20 closes at a crankshaft angle a, which is between LWOT + 150 ° KW and LWOT + 180 ° KW and - the outlet valve 21 closes at a crankshaft angle a, which lies between LWOT and LWOT + 20 ° CA closes. As a result, the largest possible gas mass flow can flow through the exhaust gas turbine 12 in overrun mode.

Description

The invention relates to an internal combustion engine charged by means of an exhaust gas turbocharger.

Internal combustion engines, which are used to drive motor vehicles, are often charged to increase performance. For this purpose, the fresh gas supplied to the combustion chambers of an internal combustion engine of the internal combustion engine is compressed by means of a fresh gas compressor. As a result, the amount of fresh gas that can be introduced into the combustion chambers and thus also the amount of fuel that can be burned there within the scope of an operating cycle can be increased.

The charging of internal combustion engines by means of exhaust gas turbochargers, which, in addition to a fresh gas compressor, also has an exhaust gas turbine integrated into an exhaust line of the internal combustion engine, is widespread. The exhaust gas turbine is driven by means of the exhaust gas flowing through it, a rotation of an impeller of the turbine being transmitted to an impeller of the compressor by means of a shaft.

A major advantage of exhaust gas turbochargers is that the energy required for compressing the fresh gas is obtained from the exhaust gas and therefore - in contrast to mechanical turbochargers that are also widely used - no useful power from the internal combustion engine is diverted.

A fundamental disadvantage of exhaust gas turbochargers, however, is that the compression output is directly dependent on the exhaust gas flow. With only a relatively small flow of exhaust gas, only a relatively low compression output is achieved. This can be noticeable in the operation of the internal combustion engine in a delayed response behavior of the internal combustion engine if the load requirement is increased after operation with little or no load and low speeds of the internal combustion engine, in particular from idling or overrun. This increased load requirement must first be converted into a correspondingly increased exhaust gas mass flow, which only then leads to an increased compression performance. This delayed response is often referred to as "turbo lag" or also with the English term "lag".

There are a variety of ways to reduce turbo lag. For example, the exhaust gas turbine of the exhaust gas turbocharger can be designed with a variable inlet geometry (so-called VTG exhaust gas turbocharger). The exhaust gas turbine has adjustable guide vanes at the turbine inlet, by means of which the flow cross section can be changed. In the case of a comparatively low flow of exhaust gas, the flow cross-section can be reduced by the guide vanes, as a result of which the flow velocity of the exhaust gas flowing into the turbine is increased.

It is also known to slow down a drop in the drive speed of the exhaust gas turbocharger in deceleration phases of a motor vehicle and thus during unfired overrun mode of the internal combustion engine by opening a throttle valve integrated in the fresh gas line as much as possible, so that the lowest possible throttling of the fresh gas line during overrun Via the internal combustion engine into the exhaust gas flow, which then drives the exhaust gas turbine in the exhaust gas flow. A resulting disadvantage is that there is an accumulation of oxygen in an exhaust gas catalytic converter which is integrated into the exhaust gas line, as a result of the gas flowing through it, which is essentially air drawn in via the fresh gas line. In order to achieve the lowest possible pollutant emissions in a first phase of a load operation of the internal combustion engine following such an overrun operation, such oxygen deposits in the catalytic converter can cause the internal combustion engine to operate temporarily with a relatively rich fuel-oxygen ratio. On the one hand, this leads to a reduced degree of efficiency during such operation of the internal combustion engine and can also cause the catalytic converter to age prematurely.

the DE 10 2013 106 391 A1 discloses a method for controlling an air intake system having an exhaust gas turbocharger for an internal combustion engine of a motor vehicle, in which the presence of an overrun mode of the internal combustion engine is detected; -Frischluftstrom is opened, wherein the thrust fresh air flow is greater than a fresh air flow in an idle mode of the internal combustion engine, an estimation of a time-added parameter relating to the thrust fresh air flow is carried out and in the event that the added parameter reaches a predefined threshold value, the The throttle valve is closed to an open position in which a lower fresh air flow than the thrust fresh air flow is set. A good response behavior can be made possible by the increased thrust / fresh air flow, whereby the time-related addition of the parameter relating to the thrust / fresh air flow adversely affects the components of the engine provided downstream of the internal combustion engine Air intake system can be avoided by excessive cooling, so that at the same time good functionality of the air intake system is made possible.

The invention was based on the object of showing an advantageous possibility of achieving the lowest or slowest possible drop in the drive speed of an exhaust gas turbocharger of the internal combustion engine during unfired overrun operation of an internal combustion engine of an internal combustion engine, in order to achieve the most advantageous possible response behavior of the internal combustion engine in a load operation following the overrun operation to realize.

This object is achieved by means of an internal combustion engine according to claim 1. A method for operating such an internal combustion engine is the subject of patent claim 7. Advantageous embodiments of the internal combustion engine according to the invention and preferred embodiments of the method according to the invention are the subjects of the further patent claims and / or result from the following description of the invention.

• - einen Verbrennungsmotor, insbesondere einen 4-Takt-Verbrennungsmotor, der mindestens einen Brennraum aufweist, in dem im Betrieb des Verbrennungsmotors ein Hubkolben zwischen einem oberen Totpunkt (OT) und einem unteren Totpunkt (UT) zyklisch bewegt wird und dem mindestens ein Einlassventil und mindestens ein Auslassventil zugeordnet sind. Als „4-Takt-Verbrennungsmotor“ wird dabei ein Verbrennungsmotor verstanden, der in einem befeuerten Lastbetrieb mit vier Takten beziehungsweise Kolbenhubbewegungen je Betriebszyklus (Arbeitsspiel) betrieben wird, wobei lediglich einer dieser Takte ein Arbeitstakt ist. Der Verbrennungsmotor einer erfindungsgemäßen Brennkraftmaschine kann insbesondere zumindest zeitweise fremdgezündet und quantitätsgeregelt und folglich in der Art eines Ottomotors betrieben werden beziehungsweise betreibbar sein.
• - einen Frischgasstrang, in den ein Frischgasverdichter eines Abgasturboladers sowie, stromab (bezüglich einer Strömungsrichtung durch den Frischgasstrang in Richtung des Verbrennungsmotors) des Frischgasverdichters, eine Drosselklappe integriert sind. Als „Drosselklappe“ wird dabei eine beliebige, vorzugsweise jedoch in Form eines Klappenventils ausgebildete Drosseleinrichtung verstanden, mittels der ein Massenstrom von über den Frischgasstrang strömendem Frischgas gezielt und aktiv einstellbar ist.
• - einen Abgasstrang, in den eine Abgasturbine des Abgasturboladers sowie, stromab (bezüglich einer Strömungsrichtung durch den Abgasstrang ausgehend von dem Verbrennungsmotor) der Abgasturbine, eine Abgasnachbehandlungseinrichtung integriert sind. Die Abgasnachbehandlungseinrichtung kann dabei eine oder mehrere Abgasnachbehandlungsvorrichtungen, insbesondere mindestens einen Abgaskatalysator (vorzugsweise ein 3-Wege-Katalysator) und einen Partikelfilter, umfassen.

According to the invention, an internal combustion engine is provided which comprises at least the following components:

• - An internal combustion engine, in particular a 4-stroke internal combustion engine, which has at least one combustion chamber in which a reciprocating piston is moved cyclically between a top dead center (TDC) and a bottom dead center (BDC) during operation of the internal combustion engine and which has at least one inlet valve and at least an exhaust valve are assigned. A “4-stroke internal combustion engine” is understood to mean an internal combustion engine that is operated in a fired load mode with four strokes or piston stroke movements per operating cycle (work cycle), with only one of these cycles being a working cycle. The internal combustion engine of an internal combustion engine according to the invention can in particular at least temporarily be externally ignited and quantity-controlled and consequently operated or be operable in the manner of an Otto engine.
• - A fresh gas line, in which a fresh gas compressor of an exhaust gas turbocharger and, downstream (with respect to a flow direction through the fresh gas line in the direction of the internal combustion engine) of the fresh gas compressor, a throttle valve are integrated. A “throttle flap” is understood to mean any throttle device, preferably in the form of a flap valve, by means of which a mass flow of fresh gas flowing through the fresh gas line can be set in a targeted and active manner.
• - An exhaust gas line, in which an exhaust gas turbine of the exhaust gas turbocharger and, downstream (with respect to a flow direction through the exhaust gas line starting from the internal combustion engine) of the exhaust gas turbine, an exhaust gas aftertreatment device are integrated. The exhaust gas aftertreatment device can include one or more exhaust gas aftertreatment devices, in particular at least one exhaust gas catalytic converter (preferably a 3-way catalytic converter) and a particle filter.

The exhaust gas aftertreatment device of an internal combustion engine according to the invention can, if necessary, be bypassed by means of an exhaust gas aftertreatment bypass which emerges from the exhaust system between the exhaust gas turbine and the exhaust gas aftertreatment device.

For such an internal combustion engine according to the invention, it is provided, on the one hand, that the throttle valve is set in an at least partially and preferably completely or as far as possible open position during unfired overrun mode. Assuming that the unfired overrun operation was preceded by a fired load operation of the internal combustion engine, it can accordingly be provided in the context of a method according to the invention for operating an internal combustion engine according to the invention that the throttle valve is at least partially and preferably in a transition from the fired load operation to the unfired overrun operation fully open position is set (if this is not already in a corresponding position). This measure according to the invention serves to achieve the lowest possible throttling of the (fresh) gas flowing over into the exhaust system from the fresh gas line via the at least one combustion chamber of the internal combustion engine during unfired overrun mode. This has an advantageous effect with regard to the desired slowing down of the drop in the drive speed of the exhaust gas turbocharger as a result of a transition to overrun mode.

Furthermore, according to the invention, a flow through the exhaust gas aftertreatment bypass is enabled and preferably a flow through the exhaust gas aftertreatment device is completely prevented. As part of a method according to the invention, such a flow through the exhaust gas aftertreatment bypass can consequently be released during a transition from a fired load operation to the unfired overrun operation and, if necessary, a flow through the exhaust gas aftertreatment device can also be blocked. This measure enables storage of Oxygen in the exhaust gas aftertreatment device from the gas that has flowed over from the fresh gas line via the internal combustion engine into the exhaust line is avoided. Bypassing the exhaust gas aftertreatment device is largely unproblematic because the overflowing gas is, in particular, air drawn in via the fresh gas line, for which no pollutant reduction by means of the exhaust gas aftertreatment device is usually required.

According to the invention it is further provided that the inlet valve closes at a crankshaft angle that is between LWOT + 150 ° CA and LWOT + 180 ° CA and the outlet valve closes at a crankshaft angle that is between LWOT-20 ° CA and LWOT. The LWOT is the top dead center that is reached by the reciprocating piston during a gas exchange in the combustion chamber. The details of these control times relate, or according to the invention, in principle to a stroke threshold of 1 mm, from which it can be assumed that the inlet and outlet valves are effectively opened. In the case of a transition from fired load operation to unfired overrun operation, a method according to the invention can provide for the closing time of the inlet valve and / or the outlet valve to be delayed, preferably by a value of between 10 ° CA and 30 ° CA, in particular between 15 ° CA and 20 ° CA, after being adjusted late. This procedure serves, on the one hand, to guide the largest possible gas flow over the internal combustion engine during unfired overrun operation by optimizing the control times for the exhaust valve in this regard. Another advantage of the valve actuations provided according to the invention for unfired overrun operation is that pronounced compression phases at least in the area of the LWOT and thus relatively high combustion chamber peak pressures are avoided. As a result, the generation of venting or blowby gas flows, that is to say of gas flows, which via the imperfectly sealed gap that is formed between the reciprocating piston and the cylinder wall of the combustion chamber, into an internal housing volume and in particular into the piston drive (connecting rod and crankshaft) Flow accommodating the internal volume of the internal combustion engine housing, are minimized. Such vent gas flows are usually, and thus also preferably in an internal combustion engine according to the invention, returned to the fresh gas line of the internal combustion engine via a housing ventilation line in order to feed them back to the at least one combustion chamber. This is to prevent components contained in the ventilation gases, in particular unburned hydrocarbons, from getting into the ambient air or from adversely affecting the components integrated therein, in particular an exhaust gas turbine and an exhaust gas aftertreatment device, when introduced into the exhaust system. A minimization of such vent gas flows is of particular importance in an internal combustion engine according to the invention or in a corresponding method for operating such an internal combustion engine, because bypassing the exhaust gas aftertreatment device by means of the exhaust gas aftertreatment bypass released in the unfired overrun mode in combination with the failure to fire the at least one combustion chamber, is also provided Substances, especially the hydrocarbons contained in the venting gases, could get into the ambient air.

For a retarded adjustment of the closing time of the exhaust valve, a phase adjuster can advantageously be used which is assigned to a camshaft which is provided for actuating the exhaust valve. By means of such a phase adjuster, the angle of rotation of the camshaft relative to the crankshaft of the internal combustion engine that drives this camshaft can be changed and the control times of the exhaust valve can thus be changed. Alternatively, for a retarded adjustment of the closing time of the exhaust valve, a switching device of a valve drive of the internal combustion engine can also be used, which has at least two switching positions that differ at least with regard to the closing time of the exhaust valve. For example, the switching device can comprise different cams of a camshaft, with different cams alternatively being able to be brought into operative connection with the exhaust valve. A fully variable valve drive with an actuating device assigned to each of the inlet and / or outlet valves can also be used.

As a result, an internal combustion engine according to the invention or a corresponding method for operating such an internal combustion engine comprises measures which, during unfired overrun mode, maximize the mass flow of gas that flows from the fresh gas line via the internal combustion engine into the exhaust line and thus flows through the exhaust gas turbine, thereby causing waste the drive speed of the exhaust gas turbocharger is avoided or at least slowed down as far as possible. At the same time, the fact that the gas flow overflowing into the exhaust system is guided via the exhaust gas aftertreatment bypass and thus at least partially bypassed the exhaust aftertreatment device partially or completely prevents oxygen from being stored in the exhaust gas aftertreatment device. In addition, the control times according to the invention for the inlet and outlet valves of the internal combustion engine generate Vent gas flows is kept low, so that bypassing the exhaust gas aftertreatment device during unfired overrun operation can also be uncritical with regard to the pollutant emissions of the internal combustion engine.

• - das Einlassventil bei einem Kurbelwellenwinkel, der zwischen LWOT-10°KW und LWOT+-10°KW liegt, öffnet und/oder
• - das Auslassventil bei einem Kurbelwellenwinkel, der zwischen LWOT-195°KW und LWOT-175°KW liegt, öffnet.

According to a preferred embodiment of an internal combustion engine according to the invention, it can be provided that during unfired overrun operation

• - The inlet valve opens and / or at a crankshaft angle that is between LWOT-10 ° CA and LWOT + -10 ° CA.
• - The exhaust valve opens at a crankshaft angle between LWOT-195 ° CA and LWOT-175 ° CA.

These control times have proven to be advantageous with regard to the desired goals, i.e. a maximization of the gas mass flow passed through the internal combustion engine and a minimization of the vent gas flows.

According to a preferred embodiment of an internal combustion engine according to the invention, it can be provided that the exhaust gas turbine comprises a VTG adjusting device, ie an adjusting device for changing a variable inlet geometry of the exhaust gas turbine, the VTG adjusting device in an at least partially and preferably as close as possible closed position during unfired overrun mode is set so that an impeller of the exhaust gas turbine is flowed against over a correspondingly small flow cross-section and thus with a relatively high flow rate of the gas. In the context of a method according to the invention, provision can accordingly be made for the VTG adjusting device to be placed in an at least partially and preferably fully closed position when there is a transition from a fired load operation of the internal combustion engine to unfired overrun operation (if it is not already in a corresponding position ). The variable inlet geometry of the exhaust gas turbine is consequently set during unfired overrun operation according to the invention in a position in which it is designed to generate the greatest possible drive power for the fresh gas compressor with a relatively small gas flow flowing through the exhaust gas turbine.

Furthermore, it can preferably be provided that the exhaust gas turbine can be bypassed, if necessary, by means of a wastegate, ie by means of a turbine bypass comprising a bypass valve, the wastegate being at least partially and preferably closed as far as possible during unfired overrun operation, so that consequently only a small proportion of a gas flow or preferably as little gas flow as possible at the exhaust gas turbine or the impeller thereof, which is conducted. In the context of a method according to the invention, provision can accordingly be made for the wastegate to be at least partially and preferably completely closed when there is a transition from a fired load operation of the internal combustion engine to unfired overrun operation (if it is not already in a corresponding position). This measure also serves to use as large a proportion as possible of the enthalpy of the gas flowing through the exhaust line to generate a drive power through the exhaust gas turbine.

According to a further preferred embodiment of an internal combustion engine according to the invention, it can be provided that an internal housing volume of the internal combustion engine is in fluid communication with a fuel vapor filter of a fuel tank system of the internal combustion engine via a housing ventilation line during unfired overrun mode. This serves to guide vent gas flows that may still occur during unfired overrun operation over the fuel vapor filter in order to filter out substances contained therein, in particular unburned hydrocarbons, from the vent gas flows. The vent gas flows filtered in this way can then be returned to the fresh gas line of the internal combustion engine via a purge gas line of the fuel tank system. An emission of hydrocarbons originating from venting gas flows during unfired overrun operation as a result of an overflow of fresh gas with (a small amount) of venting gas contained therein from the fresh gas line via the internal combustion engine into the exhaust line and via this using the exhaust gas aftertreatment bypass into the environment can be safe in this way and almost completely avoided. During a fired load operation, on the other hand, preferably no venting gas flows can be provided via the fuel vapor filter, because hydrocarbons contained therein can be introduced into the fresh gas without any problems as a result of combustion in the combustion chambers and an unintended bypassing of the exhaust gas aftertreatment device. A filtering out of such hydrocarbons by means of the fuel vapor filter, which could make its regeneration necessary earlier, is therefore preferably not provided during a fired load operation of the internal combustion engine. In the context of a method according to the invention, it can thus be provided that during a transition from a fired load operation of the internal combustion engine to the unfired overrun operation, a direct introduction of vent gas via the housing vent line into the Fresh gas line is reduced or terminated and instead vent gas is passed to the fuel vapor filter.

• 1: eine erfindungsgemäße Brennkraftmaschine gemäß einer ersten Ausgestaltungsform;
• 2: eine erfindungsgemäße Brennkraftmaschine gemäß einer zweiten Ausgestaltungsform;
• 3: die Ventilerhebungskurven beziehungsweise die Verläufe der Ventilbewegungen h der Einlassventile (dicke Linienführung) und der Auslassventile (dünne Linienführung) einerseits während eines befeuerten Lastbetriebs (durchgehende Linienführung) und andererseits während eines unbefeuerten Schubbetriebs (gestrichelte Linienführung) einer erfindungsgemäßen Brennkraftmaschine gemäß beispielsweise den 1 und 2.

The invention is explained in more detail below with reference to the exemplary embodiments shown in the drawings. The drawings show, partly in a simplified representation:

• 1 : an internal combustion engine according to the invention according to a first embodiment;
• 2 : an internal combustion engine according to the invention according to a second embodiment;
• 3 : the valve lift curves or the progression of the valve movements h of the inlet valves (thick lines) and the exhaust valves (thin lines) on the one hand during a fired load operation (continuous lines) and on the other hand during unfired overrun operation (dashed lines) of an internal combustion engine according to the invention according to, for example 1 and 2 .

the 1 and 2 each show a simplified representation of an internal combustion engine according to the invention 1 for a motor vehicle 2 . This includes a four-stroke internal combustion engine 3 , in the form of a reciprocating piston engine with four cylinders arranged in series 4th is trained. The cylinders 4th limit with reciprocating pistons guided therein 5 and a cylinder head (not shown) each have a combustion chamber 6th . The combustion chambers 6th is in operation of the internal combustion engine 3 and thus the internal combustion engine 1 Fresh gas through a fresh gas line 7th fed. The fresh gas is primarily air that is sucked in from the environment and stored in an air filter 8th is cleaned and then via a fresh gas compressor 9 , an intercooler 10 and a throttle 11 to be led. The fresh gas compressor 9 is part of an exhaust gas turbocharger that continues to be an exhaust gas turbine 12th includes, which is in an exhaust system 13th the internal combustion engine is integrated. In the exhaust system 13th is also an exhaust aftertreatment device 14th integrated, which has a 3-way catalytic converter 15 and, downstream of it, a particle filter 16 includes. The exhaust aftertreatment device 14th is, if necessary, by means of an exhaust gas aftertreatment bypass 17th bypassable, the one between the exhaust turbine 12th on the one hand and the exhaust gas aftertreatment device 14th or the catalytic converter 15th on the other hand from the exhaust system 13th going off. In this exhaust aftertreatment bypass 17th is a bypass valve 18th , for example in the form of a flap valve, integrated. Furthermore, in the means of the exhaust gas aftertreatment bypass 17th bypassable section of the exhaust system 13th an exhaust valve 19th , for example in the form of a flap valve, integrated. A gas flow that the exhaust system 13th upstream of the branch of the exhaust gas aftertreatment bypass 17th flows through, can by means of the bypass valve 18th and the exhaust valve 19th via either the exhaust aftertreatment bypass 17th or the section of the exhaust system bypassed by this 13th be guided. Only the integration of the bypass valve can be used for this function 18th be sufficient because with the bypass valve open 18th the gas flow due to the significantly higher flow resistance that occurs as a result of the flow through the exhaust gas aftertreatment device 14th would set, basically essentially via the exhaust gas aftertreatment bypass 17th would flow without there being an additional shut-off of the bypassed section of the exhaust system 13th by means of the exhaust valve 19th need. A slight flow through the exhaust gas aftertreatment device 14th could, however, possibly not be prevented, so that the additional integration of the exhaust valve 19th can be useful to such a flow through the exhaust gas aftertreatment device 14th sure to prevent.

Each of the combustion chambers 6th are two inlet valves 20th and two exhaust valves 21 assigned to that via a valve actuation device 22nd which, for example, each have a camshaft 23 for the inlet valves on the one hand 20th and on the other hand the exhaust valves 21 can include, operated.

During a fired load operation of the internal combustion engine 3 , in which this provides a drive power for the motor vehicle, the reciprocating pistons 5 due to the combustion processes in the individual combustion chambers 6th each moves in an oscillating manner between a top dead center (TDC) and a bottom dead center (BDC), the reciprocating piston 5 alternately carry out a gas exchange stroke cycle and a working stroke cycle. These cyclical movements of the reciprocating pistons 5 are transmitted by means of connecting rods (not shown) to a crankshaft (not shown), which is thereby driven in rotation. The gas exchange stroke cycle of each reciprocating piston 5 comprises an ejection stroke movement of the respective reciprocating piston 5 (corresponding to an exhaust cycle in the associated combustion chamber 6th ) as well as an intake stroke movement (corresponding to an intake stroke in the associated combustion chamber 6th ). The working stroke cycle comprises a compression stroke movement of the respective reciprocating piston 5 (corresponding to a compression stroke in the associated combustion chamber 6th ) and a working stroke movement (corresponding to a working cycle in the associated combustion chamber 6th ). The four strokes of the reciprocating pistons 5 or the four corresponding cycles during a fired load operation in the combustion chambers 6th running cycle processes correspond to an operating cycle in which respective combustion chamber 6th of the internal combustion engine 3 takes place.

The inlet valves 20th and the exhaust valves 21 are operated during the fired load operation by means of the valve actuation device 22nd open and closed at defined control times, as shown in the 3 is shown. LWOT is the top dead center of the individual reciprocating pistons 5 marked during the respective gas exchange stroke cycle. With ZOT, on the other hand, is the top dead center of the individual reciprocating pistons 5 marked during the respective working stroke cycle. The exhaust valves become more specific 21 at a crankshaft angle a that is approx. 20 ° CA before the lower UT that is before the respective LWOT, ie opened at approx. LWOT-200 ° CA and at a crankshaft angle a that is approx. 10 ° CA before the respective LWOT , ie closed at approx. LWOT-10 ° CA. The inlet valves 20th are, however, opened at a crankshaft angle a that is approx. 25 ° CA before the respective LW-TDC, ie at approx. LWOT-25 ° CA, and at a crankshaft angle a that is approx the respective LW-OT, ie closed at caLWOT + 145 ° CA. These control times also relate to operation of the internal combustion engine 3 in the nominal power point and can deviate in fired operation with other load-speed combinations.

During the fired load operation of the internal combustion engine 3 Exhaust gas is generated that is produced during the combustion of mixture quantities that are obtained from the fresh gas and, for example, directly from fuel injectors 24 into the combustion chambers 6th injected fuel. This exhaust gas is via the exhaust system 13th the internal combustion engine 1 discharged and initially flows through the exhaust gas turbine 12th . This leads to a rotating drive of an impeller (not shown) of the exhaust gas turbine 12th that about a wave 25th with an impeller (not shown) of the fresh gas compressor 9 connected is. The rotation of the impeller of the fresh gas compressor brought about in this way 9 leads to a compression of the fresh gas line 7th fresh gas flowing through, which in particular increases the performance of the internal combustion engine 3 can be realized. Downstream of the exhaust gas turbine 12th The exhaust gas then fully flows through the exhaust gas aftertreatment device 14th in order to achieve a reduction in pollutants in the exhaust gas. The bypass valve 18th is closed completely or as far as possible for this purpose, while the exhaust valve 19th is at least partially open.

In the case of unfired overrun of the internal combustion engine 3 are the reciprocating pistons 5 with deactivated fuel injection still cyclically in the cylinders 4th moved by dragging the crankshaft in rotation, as is the case when the motor vehicle coasts with the drive train engaged. To with an unfired overrun of the internal combustion engine 3 , which follows a fired overrun, to avoid a drop in the drive speed of the exhaust gas turbocharger as much as possible or at least to slow it down, it is provided that the mass flow of fresh gas that is generated as a result of this overrun of the internal combustion engine 3 from the fresh gas line 7th about the internal combustion engine 3 in the exhaust system 13th overflows, is kept as large as possible. On the one hand, the throttle valve is provided for this purpose 11 to put in their most open position. On the other hand, it is provided that the control times of the inlet valves 20th and the exhaust valves 21 compared to those for the fired load operation of the internal combustion engine 3 are intended to be adjusted late (cf. 3 ). The exhaust valves become more specific 21 in unfired overrun mode of the internal combustion engine 3 only opened at a crankshaft angle a that is approx. 5 ° CA before the lower UT that is before the LWOT, ie at approx. LWOT-185 ° CA, and at a crankshaft angle a that is approx. 10 ° CA after the LWOT is closed, ie at approx. LWOT + 10 ° CA. The inlet valves 20th are then only opened in the LWOT and closed at a crankshaft angle a that is approx. 10 ° CA before the UT that is after the LWOT, ie at approx. LWOT + 170 ° CA. Due to the delayed adjustment of the intake valve timing, which is intended for unfired overrun operation 20th and the exhaust valves 21 can be a relatively large mass flow of fresh gas flowing through the internal combustion engine 3 is channeled, can be realized. In addition, there is no pronounced compression phase in the combustion chambers in the respective LWOT 6th takes place. This leads to the fact that only comparatively small venting gas flows occur during unfired overrun operation, which flow through a housing venting line 25th from a crankcase of the internal combustion engine 3 discharged and into the fresh gas line 7th to be led back. The minimization of such vent gas flows during unfired overrun operation of an internal combustion engine according to the invention 1 can be particularly advantageous because in such a case it is also provided during unfired overrun operation that the gas flow from the fresh gas line 7th about the internal combustion engine 3 in the exhaust system 13th overflowing fresh gas not via the exhaust gas aftertreatment device 14th but as far as possible via the exhaust gas aftertreatment bypass 17. This is the bypass valve 18th partially or completely or as far as possible open and the exhaust valve 19th closed completely or as far as possible. This is intended to store oxygen from this (fresh) gas in the exhaust gas aftertreatment device 14th be avoided. Provided this (fresh) gas would still contain relevant amounts of unburned hydrocarbons as a result of a relevant mass flow of ventilation gas being introduced, namely, as a result of the flow through the exhaust gas aftertreatment bypass 17th get into the environment, which is largely avoided by minimizing the amount of ventilation gas that occurs.

As an alternative to the combined use of the bypass valve 18th as well as the exhaust valve 19th for the distribution of through the exhaust system 13th flowing gas to either the exhaust gas aftertreatment device 14th or the exhaust aftertreatment bypass 17th It is also possible to use only a 3/2-way valve that is inserted into one of the branches of the exhaust gas aftertreatment bypass 17th is integrated. By means of such a 3/2-way valve, a gas flow can only be achieved via either the exhaust gas aftertreatment device 14th or the exhaust aftertreatment bypass 17th be guided.

Emission of unburned hydrocarbons into the environment can essentially be completely prevented in the case of an internal combustion engine according to the invention 1 as in the 2 is shown. This is in addition to that according to 1 provided that during unfired overrun operation (to a relatively small extent) venting gas occurring through a corresponding position in the housing venting line 25th integrated housing ventilation valve 26th into the fuel vapor filter 27 a fuel tank system of the internal combustion engine 1 is initiated, through which the hydrocarbons are filtered out.

This fuel vapor filter 27 , which can be designed in particular in the form of an activated carbon filter, is primarily used to absorb fuel vapors that are sent via a tank ventilation line 28 a fuel tank 29 the internal combustion engine 1 led to an increasing pressure in the fuel tank 29 to balance with the ambient pressure. This increasing pressure can in particular be the result of fuel evaporating, for example, at high ambient temperatures. By absorbing the fuel vapors, their emission into the environment can be avoided. As the fuel vapor filter 27 only has a limited ability to absorb fuel vapors, it must be regenerated temporarily. For this purpose, the internal combustion engine also includes a purge gas line 30th the one hand with the fuel vapor filter 27 and on the other hand with the fresh gas line 7th connected is. During a fired load operation of the internal combustion engine 1 can temporarily by means of the in the area of the mouth of the purge gas line 30th in the fresh gas line 7th prevailing negative pressure ambient air via an ambient mouth 31 the fuel vapor filter 27 are sucked in, which is the fuel vapor filter 27 in the opposite direction to the direction of flow in which the fuel vapors from the fuel tank 29 and, in an internal combustion engine according to the invention according to FIG 2 , the vent gas flows into the fuel vapor filter 27 have flowed, flowed through and thereby flushes it. The previously in the fuel vapor filter 27 absorbed hydrocarbons are so via the fresh gas line 7th the fired combustion chambers 6th of the internal combustion engine 3 the internal combustion engine 1 fed.

List of reference symbols

1

Internal combustion engine

2

Motor vehicle

3

Internal combustion engine

4th

cylinder

5

Reciprocating piston

6th

Combustion chamber

7th

Fresh gas line

8th

Air filter

9

Fresh gas compressor

10

Intercooler

11

throttle

12th

Exhaust gas turbine

13th

Exhaust system

14th

Exhaust aftertreatment device

15th

Catalytic converter

16

Particle filter

17th

Exhaust aftertreatment bypass

18th

Bypass valve

19th

Exhaust valve

20th

Inlet valve

21

outlet valve

22nd

Valve actuation device

23

camshaft

24

Fuel injector

25th

Housing vent line

26th

Housing vent valve

27

Fuel vapor filter

28

Tank ventilation line

29

Fuel tank

30th

Purge gas line

31

Surrounding mouth

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed 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 102013106391 A1 [0008]

Claims (8)

Internal combustion engine (1) comprising - an internal combustion engine (3) which comprises at least one combustion chamber (6) in which a reciprocating piston (5) cyclically between a top dead center (TDC) and a bottom dead center (BDC) when the internal combustion engine (1) is in operation is moved and to which at least one inlet valve (20) and one outlet valve (21) are assigned, - a fresh gas line (7) in which a fresh gas compressor (9) of an exhaust gas turbocharger and, downstream of the fresh gas compressor (9), a throttle valve (11) are integrated and - an exhaust gas line (13) into which an exhaust gas turbine (12) of the exhaust gas turbocharger and, downstream of the exhaust gas turbine (12), an exhaust gas aftertreatment device (14) are integrated, characterized in that the exhaust gas aftertreatment device (14), if necessary, by means of an exhaust gas aftertreatment bypass ( 17) can be bypassed, which goes off between the exhaust gas turbine (12) and the exhaust gas aftertreatment device (14) from the exhaust gas line (13), and that during an unfired thrust riebs - the throttle valve (11) is set in a partially or as far as possible open position and - a flow through the exhaust gas aftertreatment bypass (17) is released and - the inlet valve (20) at a crankshaft angle (a) which is between LWOT + 150 ° KW and LWOT + 180 ° CA, closes and - the exhaust valve (21) closes at a crankshaft angle (a) which is between LWOT and LWOT + 20 ° CA. Internal combustion engine (1) according to Claim 1 , characterized in that during unfired overrun operation - the inlet valve (20) opens at a crankshaft angle (a) which is between LWOT-10 ° KW and LWOT + 10 ° KW and / or - the outlet valve (21) opens at a crankshaft angle (a), which is between LWOT-195 ° CA and LWOT-175 ° CA, opens. Internal combustion engine (1) according to one of the preceding claims, characterized in that the exhaust gas turbine (12) comprises a VTG adjusting device, the VTG adjusting device being set in a partially or as close as possible closed position during unfired overrun mode. Internal combustion engine (1) according to one of the preceding claims, characterized in that the exhaust gas turbine (12) can be bypassed if necessary by means of a wastegate, the wastegate being partially or as far as possible closed during unfired overrun mode. Internal combustion engine (1) according to one of the preceding claims, characterized in that a flow through the exhaust gas aftertreatment device (14) is completely prevented during unfired overrun mode. Internal combustion engine (1) according to one of the preceding claims, characterized in that during unfired overrun operation, an internal housing volume of the internal combustion engine (3) is in fluid-conducting connection via a housing ventilation line (25) with a fuel vapor filter (27) of a fuel tank system of the internal combustion engine (1). A method for operating an internal combustion engine (1) according to any one of the preceding claims, characterized in that in the event of a transition from a fired load operation of the internal combustion engine (3) to unfired overrun operation - the throttle valve (11) is placed in a partially or as widely as possible open position and / or - a flow through the exhaust gas aftertreatment bypass (17) is released and / or - the opening and / or closing time of the inlet valve (20) and / or the outlet valve (21) is delayed and / or - the VTG adjusting device in a partially or as far as possible closed position and / or - the wastegate is partially or as far as possible closed and / or - a direct introduction of a ventilation gas flow via the housing ventilation line (25) into the fresh gas line (7) is reduced or terminated and instead the ventilation gas flow to the fuel vapor filter is reduced (27) is performed. Procedure According to Claim 7 , characterized in that the closing time of the inlet valve and / or the outlet valve is delayed by a value between 10 ° CA and 30 ° CA.

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