DE102016223222A1 - A spark-ignition internal combustion engine, and method for operating a spark-ignition internal combustion engine - Google Patents

Abstract

The invention relates to a spark-ignition internal combustion engine (10) having at least one combustion chamber (12), wherein the combustion chamber (12) at least one inlet valve (14) is associated, which in the open state, the inflow of fluid from a suction pipe (18) into the combustion chamber ( 12), and wherein at least one outlet valve (16) is associated with the combustion chamber (12), which in the opened state allows the outflow of fluid from the combustion chamber (12) into an exhaust passage (20), at least one additional purge gas passage (22). is provided, which leads either directly into the combustion chamber (12) and / or immediately before the inlet valve (14) in the suction pipe (18). The invention further relates to a method for operating a spark-ignited internal combustion engine (10).

Description

The invention relates to a spark-ignition internal combustion engine according to the preamble of claim 1. Furthermore, the invention relates to a method for operating a spark-ignited internal combustion engine. The internal combustion engine can therefore be, in particular, a direct-injection engine or an engine with intake manifold injection.

Out DE 10 2015 204 505 A1 a method is known for operating a spark-ignited, direct-injection internal combustion engine with at least one combustion chamber, to which an inlet valve and an outlet valve are assigned. According to this method, the intake valve and the exhaust valve are concurrently opened (scavenging) at a time to allow an air mass flow serving as purge flow to flow directly to the exhaust valve via the intake valve through the combustion chamber. By means of an injection element arranged downstream of the combustion chamber, fuel can be supplied to the purge stream as required, in order to achieve a desired air ratio of λ = 1. + -. 0.05 in the purge stream. Although this method can be done an efficient post-treatment. But it requires an additional fuel input.

The invention has for its object to provide an internal combustion engine and a method for operating an internal combustion engine is available, with which the Spülstrommenge is increased by the combustion chamber of a spark-ignition internal combustion engine and at the same time an efficient exhaust aftertreatment can be performed.

The object is achieved according to the invention with the features of the independent claims. Further practical embodiments and advantages of the invention are described in connection with the dependent claims.

A spark-ignited internal combustion engine according to the invention has at least one combustion chamber, wherein the combustion chamber is associated with at least one inlet valve, which allows in the open state, the flow of fluid from a suction pipe into the combustion chamber. In the present case, combustion fluid flowing through the inlet valve is referred to as combustion air and / or a purge gas to be defined in more detail. By combustion air is meant in particular fresh air or a mixture of fresh air and recirculated exhaust gas and / or blow-by gas. The introduction of combustion air into the combustion chamber essentially serves to be burned together with fuel to do work and in particular to provide drive energy. The combustion chamber is also associated with at least one outlet valve, which in the opened state allows the outflow of fluid from the combustion chamber into an exhaust gas duct. The fluid flowing out via the outlet valve is, in particular, exhaust gas formed in the combustion chamber during a combustion process and / or purge gas. In an internal combustion engine according to the invention, at least one additional purge gas channel (for introducing a purge gas deviating from combustion air) is provided which either leads directly into the combustion chamber and / or leads into the intake pipe immediately before the intake valve. By means of such a purge gas channel, purge gas can accordingly either be conducted directly into the combustion chamber and / or immediately before the inlet valve into the intake manifold.

A purge gas is understood in particular to mean a reaction-inert gas, preferably an inert gas, which behaves in a temperature-stable manner under the conditions prevailing in the combustion chamber. The oxygen content (here in the form of free O ₂ ) of a purge gas conducted through the purge gas channel is preferably significantly reduced from the oxygen content in the combustion air. For example, it has an oxygen content of at most 10 percent, preferably at most 5 percent, at most 2 percent or at most 1.5 percent.

In order to use the purge gas for purifying exhaust gas remaining in the combustion chamber after a combustion phase, it is preferably first introduced into the intake manifold via a purge gas channel leading directly into the intake manifold upstream of the intake valve and introduced into the combustion chamber by means of the inlet valve and / or it is a separate, directly into the combustion chamber leading purge gas channel provided, which makes it possible to introduce purge gas regardless of the state of the intake valve in the combustion chamber. For an efficient purging of the combustion chamber, a positive pressure gradient between intake manifold and exhaust duct is required, in particular if no further technical aids are provided in order to generate a purging flow directed in the direction of the exhaust duct. In this case, the pressure in the suction tube is preferably at least 1 bar, preferably at least 1.5 bar and particularly preferably at least 3 bar.

An internal combustion engine according to the invention offers the possibility of using an inert gas for the conveyance and flushing of exhaust gas from the combustion chamber, which - compared with the use of combustion air from the intake manifold - is associated with the following advantages.

On the one hand, the amount of purge gas can be increased since purge gas has a reduced oxygen content compared with combustion air, in particular with respect to oxygen-rich ambient air. This due to the flow through the Combustion chamber without prior combustion via the exhaust valve into the exhaust duct passing purge gas (either by scavenging and / or introducing purge gas through a separate purge gas channel and discharge via an exhaust valve) thus loaded exhaust aftertreatment systems significantly lower than when using combustion air for scavenging for purging of exhaust gas the combustion chamber. The exhaust aftertreatment can therefore be significantly improved with the same flushing quality or the burden of exhaust aftertreatment systems can be reduced. In particular, with an internal combustion engine according to the invention, even at high flow rates of purge gas during operation of the internal combustion engine, an air ratio of λ = 1 ± 0.05 can be maintained.

In summary, through the use of a purge gas channel and the use of an (inert) purge gas, the Spülstrommenge be increased in order to free the combustion chamber more efficient from residual - possibly still reactive - hot exhaust gas. As a result, the risk of knocking or knocking of the internal combustion engine is reduced.

If, in an internal combustion engine according to the invention, the introduction of the purge gas takes place immediately before the inlet valve in the intake manifold, immediately after opening the inlet valve exclusively or at least predominantly (ie in particular at least 80 percent, at least 90 percent or at least 95 percent) purge gas in the Passed combustion chamber. The purge gas is positioned before opening the intake valve immediately upstream of the inlet valve as an upstream purge gas. Upstream of the upstream purge gas is available combustion air in the intake manifold. If the inlet valve is opened, first of all, or at least predominantly, the upstream quantity of purge gas flows into the combustion chamber and then combustion air. Preferably, in this case, the internal combustion engine is designed so that the total amount of inflowing fluid during an opening phase of the intake valve to a maximum of 25 percent purge gas and that the purge gas flows exclusively in the first half of the opening phase, in particular within the first third or the first quarter the opening phase of the intake valve. The inflow phase of purge gas may alternatively or in addition also be limited such that it takes place exclusively before the closing time of the at least one outlet valve, in particular to allow the inflowing purge gas still an outflow before closing the exhaust valve.

In a practical embodiment of an internal combustion engine according to the invention, the flushing gas duct has a fluid connection to the exhaust duct in order to use recirculated exhaust gas as purge gas. Preferably, downstream of the combustion chamber and upstream of the Spülgaskanalendes an exhaust aftertreatment system - in particular and preferably in the form of a catalyst and / or in the form of a device for blowing of oxidizing and / or reducing agents - arranged. This has the advantage that the exhaust gas passed through the exhaust aftertreatment system is again reduced in its reactivity. The exhaust gas is then correspondingly inert and temperature stable and therefore particularly suitable as a purge gas.

When the purge gas passage is in fluid communication with a high pressure region of the exhaust passage downstream of the combustion chamber, a pressure in the high pressure region may be utilized to deliver exhaust gas into the purge gas passage. In particular, no further means for conveying exhaust gas into the purge gas channel are then required at sufficiently high pressure, in particular, no pump is required. A high-pressure region is understood in particular to be those portions of exhaust gas channels in which phase-wise pressures of at least 3 bar, at least 3.5 bar or at least 4 bar prevail.

Regardless of whether the purge gas channel is in fluid communication with a high pressure region of the exhaust passage, it may be advantageous to place a check valve in the purge gas passage, particularly to avoid backflow of exhaust gas from the purge gas passage into the exhaust passage under varying pressure conditions.

Alternatively or in addition to exhaust gas can be used as purge gas in particular nitrogen or water vapor. These gases are also inert and stable in temperature and in particular contain no free oxygen (in particular in the form of O ₂ ) or only very small amounts thereof.

In a further practical embodiment, a pump and / or a check valve is arranged in the purge gas channel.

By means of a pump, any desired purge gas can be actively and at any time conveyed through the purge gas channel into the combustion chamber and / or into the intake pipe immediately before the intake valve. The use of a pump is particularly useful if purge gas in the form of exhaust gas from an exhaust duct region with a low absolute pressure (eg less than 3 bar, less than 2 bar or less than 1.5 bar) to be promoted or if exhaust gas is to be conveyed from an exhaust duct region in the suction pipe, which has a low pressure during the desired delivery time relative to the suction pipe.

As a pump, in a particularly practical embodiment, a secondary air pump can be used, which is used in certain first operating states of the internal combustion engine, in particular at low temperature of the internal combustion engine and low load requirements, for conveying secondary air. In operating conditions of the internal combustion engine with high temperature and high load requirements, the secondary air pump can be used as needed to promote purge gas through the purge gas channel. In this case, a secondary air duct may also be used as a purge gas passage at the same time so that at low load requirements to the engine and low temperatures of the secondary air duct is used according to its original intended use for the passage of secondary air and is used in operating conditions with higher load requirements and temperatures for purge gas , In the secondary air operation, the secondary air pump promotes air from the suction pipe in the direction of the exhaust duct, for the purge gas operation, the secondary air pump promotes exhaust gas serving as purge gas in the opposite direction from the exhaust duct into the intake manifold. As an operating state with low load request and temperature, for example, an operating phase of the internal combustion engine is considered immediately after a cold start, the other operating conditions relate to a partial load operation and / or full load operation of the internal combustion engine, especially at speeds above 1500 rpm, above 2,000 rpm or above 2,500 rpm.

As mentioned above, a pump may be dispensed with and the provision of a check valve in the purge gas passage may be sufficient if pressure oscillations in the exhaust passage are sufficient to deliver a sufficient amount of exhaust gas through the purge gas passage.

At the at least one inlet valve, a closure device for closing the purge gas channel as required can be arranged or formed. With such a closure device, the purge gas channel can be closed and thus a certain amount of purge be separated by, if necessary, prevented by closing the closure device that further purge gas flows from the purge gas channel into the combustion chamber and / or in the suction tube. An arranged in the region of the inlet valve closure device is particularly suitable for a purge gas channel, which opens into the intake pipe immediately before the inlet valve.

In this case, the closure device is preferably arranged or designed such that the movement of the inlet valve during opening and / or closing is used to control the closure device. For this purpose, the closure device can in particular use the valve stem of an inlet valve as closure element, for example by forming a radially outstanding shoulder extending in the circumferential direction of the inlet valve on the stem of the inlet valve, which in certain positions of the inlet valve into the suction tube and / or into the combustion chamber leading end portion of the purge gas channel releases and closes this end portion in other positions. Thus, on the one hand a desired amount of purge gas can be separated and provided for the next flushing process, and on the other hand it can be ensured that in certain phases of the gas exchange, in particular in a second half during an inlet phase, no purge gas can flow into the combustion chamber. This avoids that larger amounts of purge gas are included together with combustion air for a subsequent combustion process in the combustion chamber in order to achieve a high load point in the combustion can.

In a further practical embodiment, a control device, an exhaust aftertreatment system (in particular in the form of a catalyst and / or a device for injecting oxidizing and / or reducing agents) and / or an exhaust gas cooler are arranged in the purge gas channel. Suitable as a control device are in particular a valve or a throttle. By means of a control device, as an alternative or in addition to the closure device described above, a predetermined amount of purge gas can be passed through the purge gas channel into the combustion chamber and / or into the intake manifold. The upstream purge gas can be determined by means of the control device.

By means of an exhaust aftertreatment system, exhaust gas from the combustion chamber is oxidized and / or reduced and thus reduces the reactivity of the exhaust gas. A arranged in the purge gas exhaust gas aftertreatment system can be used either for the aftertreatment of directly flowing from the combustion chamber exhaust gas or for further treatment of exhaust gas, which has already passed a catalyst of conventional exhaust aftertreatment in the exhaust system.

When, as described last, exhaust gas downstream of a conventional exhaust aftertreatment catalyst is diverted into the purge gas channel, i. the branch is arranged in the purge gas channel downstream of such a catalyst, a means for conveying the exhaust gas must be provided, in particular in the form of a pump.

In addition, the temperature of the purge gas, in particular of used as purge gas Exhaust gas can be lowered by means of an exhaust gas cooler to further reduce the reactivity.

The invention has been particularly made for multi-cylinder reciprocating internal combustion engines, particularly those having one, two, three, four, five, six, eight, ten, twelve or sixteen cylinders. Furthermore, the invention has been made especially for internal combustion engines with a specific power of at least 60 kW / 1,000 cc.

1. a) Öffnen des mindestens einen Auslassventils zum Ausströmen von Fluid aus dem Brennraum in den Abgaskanal;
2. b) Einleiten einer vorbestimmten Menge an Spülgas in den Brennraum, wobei das Spülgas innerhalb eines vorbestimmten Zeitraums zwischen 10° KW und 75° KW in den Brennraum geleitet wird und über das mindestens eine Auslassventil aus dem Brennraum ausströmt;
3. c) Einleiten von für die Verbrennung in dem Brennraum vorgesehener Verbrennungsluft aus dem Saugrohr in den Brennraum durch das mindestens eine geöffnete Einlassventil und Schließen des Auslassventils;
4. d) Schließen des Einlassventils.

The invention also relates to a method for operating a spark-ignited internal combustion engine having at least one combustion chamber, wherein at least one inlet valve is associated with the at least one combustion chamber, which allows the flow of fluid from a suction pipe into the combustion chamber in the open state. Under an incoming fluid in this context, both combustion air according to the above definition and purge gas understood. The combustion chamber is assigned at least one outlet valve which, in the opened state, allows the outflow of fluid from the combustion chamber into an exhaust gas duct. In particular exhaust gas, purge gas and (not burned, promoted by the combustion chamber) combustion air into consideration as effluent fluids. The internal combustion engine used for the method may also have one or more of the features described above or below. According to a method according to the invention, the following method steps are carried out in the stated sequence during a charge exchange process, at least during certain operating phases of the internal combustion engine:

1. a) opening the at least one outlet valve for the outflow of fluid from the combustion chamber into the exhaust gas duct;
2. b) introducing a predetermined amount of purge gas into the combustion chamber, wherein the purge gas is passed within a predetermined period of time between 10 ° CA and 75 ° CA in the combustion chamber and flows out of the combustion chamber via the at least one exhaust valve;
3. c) introducing combustion air provided for combustion in the combustion chamber from the intake manifold into the combustion chamber through the at least one opened intake valve and closing the exhaust valve;
4. d) closing the inlet valve.

The two processes mentioned in process step c) can be carried out in the order named or in the reverse order or simultaneously.

If the purge gas is introduced via at least one separate purge gas valve (which will be explained in more detail below), it is preferable if the exhaust valve closes before combustion air is introduced via the intake valve to allow combustion air to flow through the combustion chamber to the exhaust valve (scavenging). to avoid. If, on the other hand, purge gas is introduced into the combustion chamber via the inlet valve, it may be preferable or even necessary for a certain subset of combustion air to flow into the combustion chamber through the opened intake valve before the exhaust valve is closed.

An advantage of the method is, as already explained above, that an efficient flushing of reactive exhaust gas can take place from the combustion chamber by not combustion air, but an inert - preferably inert - purge gas is used with respect to air reduced oxygen content. This can promote a large amount of purge gas for purging the combustion chamber through this over a relatively long purging and the tendency to knock the engine are reduced.

The purge gas can in particular be passed directly into the combustion chamber via a purge gas channel and a purge gas channel valve leading directly into the combustion chamber, wherein the at least one inlet valve is opened after introducing a predetermined amount of purge gas for introducing the combustion air from the intake manifold into the combustion chamber. The purging gas valve can be opened and closed independently of the inlet valve to introduce a predetermined amount of purge gas over a predetermined period of time in the combustion chamber.

Alternatively or in addition thereto, purge gas can be conducted into the intake pipe directly in front of the at least one intake valve in such a way that an upstream quantity of purge gas accumulates immediately in front of the intake valve which then flows into the exhaust gas passage through the combustion chamber via an open exhaust valve immediately upon opening of the intake valve can.

When the purge gas is introduced into the combustion chamber via the intake manifold and the intake valve, in an initial opening phase of the intake valve, the inflowing gas amount to at least 50 percent, preferably at least 70 percent, more preferably at least 80 percent, at least 90 percent or at least 95 percent by volume from purge gas. In particular, the inlet valve should be considered open when a valve lift occurs, preferably when the valve lift is at least 0.5 mm, and more preferably when the valve lift is at least 1 mm. If that in one Beginning opening phase inflowing fluid does not consist of 100 percent purge gas, the remaining portion consists in particular exclusively or at least predominantly from combustion air. Under combustion air is - as already mentioned - understood in particular ambient air, which may optionally be mixed with recirculated exhaust gas and / or with blow-by gas.

In connection with a method according to the invention, due to the use of a purge gas, the inlet valve and the outlet valve can be opened simultaneously over an (unusually large) range of at least 10 ° CA to 75 ° CA. Thereby, a large amount of purge gas can be conveyed through the combustion chamber. In this context, in particular the phase in which both the inlet valve and the outlet valve have a minimum valve lift of 1 mm is regarded as the opening time.

Also in connection with the methods can be used as purge gas in particular recirculated exhaust gas from the exhaust passage.

The purge gas volume is preferably at most 25 percent of the total fluid flowing into the combustion chamber during a gas exchange phase, i. the total amount of combustion air and purge gas. Further, the purge gas, exclusively or at least predominantly (ie in particular at least 80 percent, at least 90 percent or at least 95 percent) is introduced into the combustion chamber, while the exhaust valve is open, so that it unfolds its flushing effect and flue gas remaining in particular in the combustion chamber out of the combustion chamber. As a result, the combustion chamber is first flushed by means of purge gas. Subsequently, exclusively or predominantly, combustion air (predominantly in the form of ambient air with a pure oxygen content of about 21 percent) is introduced into the combustion chamber in order to expel preferably the purge gas from the combustion chamber and after closing the exhaust valve a sufficient amount of combustion air for a to promote subsequent combustion process in the combustion chamber.

The method is provided in particular for operating states in which the internal combustion engine is under high partial load or under full load. Especially for speeds between 1000 rpm and 7000 rpm. In this respect, it is also true when it is partially applied during operation of an internal combustion engine. The method is preferably used when the temperatures in the combustion chamber are already increased. In particular, the method is used from an intake manifold pressure of greater than 0.7 bar or greater than 1 bar, preferably greater than 1.5 bar and particularly preferably greater than 2 bar.

• 1 einen Ausschnitt einer ersten Ausführungsform einer erfindungsgemäßen Brennkraftmaschine mit einem Einlassventil, einem Auslassventil und einem Spülgaskanal in einem schematischen Längsschnitt,
• 2 die erste Ausführungsform der erfindungsgemäßen Brennkraftmaschine aus 1 in einer schematischen Darstellung,
• 3 den Ventilhub des Einlassventils und des Auslassventils in Abhängigkeit des Kurbelwinkels für die erste Ausführungsform einer erfindungsgemäßen Brennkraftmaschine gemäß den 1 und 2,
• 4 eine zweite Ausführungsform der erfindungsgemäßen Brennkraftmaschine in einer schematischen Darstellung, und
• 5 den Ventilhub des Einlassventils, des Auslassventils und eines Spülgasventils in Abhängigkeit des Kurbelwinkels für die zweite Ausführungsform einer erfindungsgemäßen Brennkraftmaschine gemäß 4.

Further practical embodiments of the invention are described below in conjunction with the drawings. Show it:

• 1 1 a detail of a first embodiment of an internal combustion engine according to the invention with an inlet valve, an outlet valve and a flushing gas channel in a schematic longitudinal section,
• 2 the first embodiment of the internal combustion engine according to the invention 1 in a schematic representation,
• 3 the valve lift of the intake valve and the exhaust valve as a function of the crank angle for the first embodiment of an internal combustion engine according to the invention according to the 1 and 2 .
• 4 a second embodiment of the internal combustion engine according to the invention in a schematic representation, and
• 5 the valve lift of the intake valve, the exhaust valve and a purge gas valve as a function of the crank angle for the second embodiment of an internal combustion engine according to the invention 4 ,

In 1 is a section of a first embodiment of a spark-ignition internal combustion engine according to the invention 10 shown. In the clipping is an upper part of a combustion chamber 12 pictured, taking the combustion chamber 12 two inlet valves 14 and two exhaust valves 16 assigned. When the inlet valve is open 14 , which moves to open in the direction of the arrow E, a fluid from a suction pipe 18 in the combustion chamber 12 flow. With the exhaust valve open 16 , which opens in the direction of the arrow A, a fluid, here exhaust or purge gas from the combustion chamber 12 in an exhaust duct 20 stream.

In 2 is the first embodiment of the spark-ignition internal combustion engine according to the invention 10 shown in a schematic representation. Here are next to the combustion chamber 12 also the two intake valves 14 and the two exhaust valves 16 shown. From the respective part of the suction pipe 18 can a fluid, in particular combustion air or purge gas, through the respective open inlet valve 14 in the combustion chamber 12 flow and out of each open exhaust valves 16 in the exhaust ducts 20 stream.

As can be seen, is a purge gas channel 22 provided immediately before the respective inlet valve 14 in the respective part of the suction tube 18 empties. It can, as in 2 shown, respectively per inlet valve 14 a purge gas channel 22 be provided to a maximum amount of purge gas in the combustion chamber 12 to lead.

Alternatively, only for one intake valve 14 a purge gas channel 22 be provided. In this case, it is preferable if intake valves 14 with flushing gas channel 22 used for scavenging rinsing and other inlet valves 14 only be opened when the exhaust valves 16 are closed.

As in 1 is clearly visible, is the purge gas channel 22 fluid-conducting with the exhaust duct 20 connected, so that purge gas, in this case exhaust gas from the exhaust passage 20 through the purge gas channel 22 in the suction pipe 18 can flow. The purge gas channel 22 here branches immediately downstream of the combustion chamber 12 from the exhaust duct 20 from.

In the purge gas channel 22 are optional a control device 24 , a pump 26 , an exhaust gas cooler 28 , a catalyst serving as an exhaust aftertreatment system 30 and / or a check valve 32 arranged. Alternatively or in addition thereto, a device for injecting reducing agents and / or oxidizing agents may also be provided which are in the region of one in the purge gas channel 22 provided reduction section or oxidation path acts. At the control device 24 this is a control valve 34 , The control device 24 In particular, it can be used to separate a certain quantity of purge gas which is produced during one of the following charge exchange processes through the purge gas channel 22 in the suction pipe 18 and then through the combustion chamber 12 should be encouraged.

Alternatively, as a control device 24 a throttle, not shown here can be used.

The exhaust gas cooler 28 can be used in particular to the temperature of the purge gas, or by the purge gas channel 22 Lowering the flowing exhaust gas to further increase the inertness of the purge gas and thermally relieve the pump. Also through the catalyst 30 can be caused that the purge gas is less reactive and in particular inert.

The check valve 32 is intended, under unfavorable pressure conditions, a backflow of exhaust gas from the purge gas channel 22 in the exhaust duct 20 to avoid.

If, regardless of prevailing pressure conditions, it should be ensured that exhaust gas from the exhaust duct is active at all times 20 in the purge gas channel 22 can be encouraged, it is beneficial to have a like in 1 illustrated optional pump 26 provided. By means of the pump 26 can then at any time, if necessary, purge gas from the exhaust passage 20 through the purge gas channel 22 in the suction pipe 18 be encouraged. In this case, it is also possible, the exhaust gas downstream of a catalyst (not shown here) in the exhaust passage 20 to remove and on a catalyst 30 in the purge gas channel 22 to renounce.

As in 1 is shown in addition to the inlet valve 14 a closure device 36 arranged. The closure device 36 is here as a in the radial direction of a valve stem 38 of the inlet valve 14 formed outwardly extending collar. The collar provides fluid communication between the purge gas channel 22 and the suction tube 18 free when the inlet valve 14 - as in 1 shown - is closed and closes this fluid connection by moving down when the inlet valve 14 moves down to open.

Combined with 3 Below is the operation of the first embodiment of the internal combustion engine according to the invention 10 explained. First, purge gas is in the form of - preferably inert - exhaust gas from the exhaust passage 20 over the purge gas channel 22 in the suction pipe 18 immediately before the respective intake valve 14 initiated. The inlet valve 14 is closed, so here is an upstream amount of purge gas 40 forms (cf. 1 ), located just in front of the inlet valve 14 accumulates. As in 3 based on the valve lift curve of the exhaust valve 42 and the valve lift curve of the intake valve 44 shown, initially open the exhaust valves 16 , so that the exhaust gases generated during combustion from the combustion chamber 12 in the exhaust duct 20 can flow. Subsequently, the intake valves also open 14 , so that first the upstream purge gas 40 in the combustion chamber 12 flows.

After flowing in the upstream purge gas 40 combustion air flows out of the intake manifold 18 in the combustion chamber 12 , By means of the control valve 34 and the closure device 36 is doing the upstream purge gas 40 regulated. Immediately with the opening of the inlet valves 14 is with the closure device 36 the purge gas channel 22 closed, so that from this point on no more purge gas into the intake manifold 18 can flow in.

How good in 3 at the valve lift curve of the intake valve 44 and at the valve lift curve of the exhaust valve 42 it can be seen, are the exhaust valve 16 and the inlet valve 14 over a predetermined time t, here 45 ° KW, open at the same time. This corresponds in particular to the time which the predetermined upstream amount of purge gas 40 needed to get off the intake valves 14 by the combustion chamber 12 to the exhaust valves 16 in the exhaust duct 20 to stream. Then close the exhaust valves 16 , and about the intake valves 14 only combustion air flows into the combustion chamber 12 , Then close the intake valves 14 , and the following combustion takes place.

In conjunction with the 4 and 5 is a second embodiment of a spark-ignition internal combustion engine according to the invention 10 explained. An essential difference of this second embodiment over the first embodiment is that the additional purge gas channel 22 directly into the combustion chamber 12 empties.

For description of the second embodiment, the same reference numerals are used for identical or at least functionally identical elements, as for the description of the first embodiment.

How good in 4 is recognizable, are the combustion chamber 12 two inlet valves 14 and two exhaust valves 16 assigned. Furthermore, the combustion chamber 12 a separate purge gas valve 46 assigned, via which purge gas from a directly into the combustion chamber 12 opening Spülgaskanal 22 in the combustion chamber 12 is directed.

Based on the valve lift curve of the intake valve 44 , the valve lift curve of the exhaust valve 42 and the valve lift curve of the purge gas valve 48 in 5 becomes the method for the operation of this second embodiment of the internal combustion engine according to the invention 10 explained. First, the exhaust valves 16 open so that the exhaust gases generated during combustion through the exhaust valves 16 in the exhaust duct 20 stream. Then this is directly into the combustion chamber 12 opening flush valve 46 opened and purge gas flows from the purge gas channel 22 in the combustion chamber 12 and through the open exhaust valves 16 in the respective exhaust duct 20 , The predetermined period t, in the purge gas in the combustion chamber 12 flows, is thereby of the opening time of Spülgasventils 46 certainly. Only after the complete closing of the exhaust valves 16 become the intake valves 14 opened so that it is ensured that no combustion air directly from the intake manifold 18 through the inlet valves 14 in the combustion chamber 12 and about the exhaust valves 16 in the exhaust duct 20 can flow. It is thus only in a previous combustion remaining exhaust gas and purge gas from the combustion chamber 12 in the exhaust duct 20 promoted. Combustion air can thus only into the combustion chamber 12 be promoted and remains there until the subsequent combustion process has taken place and the exhaust valves 42 then open again. The purge gas valve 48 is preferably - as in 5 shown - closed after the exhaust valves 42 closed or simultaneously with the closing of the exhaust valves 42 , It is also possible the purge gas valve 48 already close before the exhaust valves 42 are closed, especially if it is ensured that the pressure level in the exhaust duct 20 lower than in the combustion chamber 12 to a backflow of exhaust gas from the exhaust duct 20 in the combustion chamber 12 to avoid.

The features of the invention disclosed in the present description, in the drawings and in the claims may be essential both individually and in any desired combinations for the realization of the invention in its various embodiments. The invention may be varied within the scope of the claims and in consideration of the knowledge of the person skilled in the art.

LIST OF REFERENCE NUMBERS

10

Internal combustion engine

12

combustion chamber

14

intake valve

16

outlet valve

18

suction tube

20

exhaust duct

22

purge gas

24

control device

26

pump

28

exhaust gas cooler

30

catalyst

32

check valve

34

control valve

36

closure device

38

valve stem

40

upstream amount of purge gas

42

Valve lift curve of the exhaust valve

44

Valve lift curve of the intake valve

46

purge gas valve

48

Valve lift curve of the purge gas valve

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102015204505 A1 [0002]

Claims (10)

A spark-ignited internal combustion engine having at least one combustion chamber (12), wherein the combustion chamber (12) at least one inlet valve (14) is associated, which in the open state, the inflow of fluid from a suction pipe (18) into the combustion chamber (12) allows, and wherein the At least one exhaust valve (16) is associated with the combustion chamber (12), which in the open state, the outflow of fluid from the combustion chamber (12) into an exhaust passage (20), characterized in that at least one additional purge gas channel (22) is provided either directly into the combustion chamber (12) and / or immediately before the inlet valve (14) into the suction pipe (18) leads. Internal combustion engine according to the preceding claim, characterized in that the purge gas passage (22) has a fluid connection to the exhaust passage (20) to utilize recirculated exhaust gas as purge gas. Internal combustion engine according to one of the preceding claims, characterized in that in the purge gas channel (22) a pump (26) and / or a check valve (32) is arranged. Internal combustion engine according to one of the preceding claims, characterized in that arranged on the at least one inlet valve (14) is a closure device (36) for closing the purge gas channel (22) as required. Internal combustion engine according to one of the preceding claims, characterized in that in the purge gas channel (22) a control device (24), an exhaust aftertreatment system and / or an exhaust gas cooler (28) is arranged. Method for operating a spark-ignited internal combustion engine (10) having at least one combustion chamber (12), wherein the at least one combustion chamber (12) at least one inlet valve (14) is associated, which in the open state, the inflow of fluid from a suction pipe (18) in the Combustion chamber (12) allows, and wherein the combustion chamber (12) at least one outlet valve (16) is associated, which allows the outflow of fluid from the combustion chamber (12) in an exhaust passage (20) in the open state, wherein the following method steps are carried out: a) opening the at least one outlet valve (16) for the outflow of fluid from the combustion chamber (12) into the exhaust duct (20); b) introducing a predetermined amount of a purge gas into the combustion chamber (12), wherein the purge gas within a predetermined period between 10 ° KW to 75 ° KW in the combustion chamber (12) is passed and via the at least one outlet valve (16) from the Combustion chamber (12) flows out; c) introducing a combustion fluid in the combustion chamber (12) from the intake manifold (18) into the combustion chamber (12) through at least one opened intake valve (14) and closing the exhaust valve (16); d) closing the inlet valve (14). Method according to the preceding claim, characterized in that the purge gas via a purge gas channel (22) and a directly into the combustion chamber (12) leading Spülgaskanalventil (46) is passed directly into the combustion chamber (12) and the inlet valve (14) after introduction of a certain amount of purge gas for introducing the fluid from the suction pipe (18) into the combustion chamber (12) is opened. Method according to Claim 6 , characterized in that the purge gas is directed into the intake pipe (18) immediately before the inlet valve (14) that immediately after opening the inlet valve (14) initially predominantly purge gas through the inlet valve (14) through the combustion chamber (12) the opened exhaust valve (16) flows into the exhaust passage (20). Method according to one of the three preceding claims, characterized in that the inlet valve (14) and the outlet valve (16) over a range of at least 10 ° CA to 75 ° KW are opened simultaneously. Method according to one of the preceding claims, characterized in that as purge gas recirculated exhaust gas from the exhaust passage (20) is used and / or that the purge gas volume is at most 25 percent of the total in the combustion chamber (12) inflowing volume of purge gas and other fluid.

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