WO2012076183A1

WO2012076183A1 - Internal combustion engine, exhaust valve and cylinder head therefor, and production, operation and use of an internal combustion engine

Info

Publication number: WO2012076183A1
Application number: PCT/EP2011/006219
Authority: WO
Inventors: David Larsson
Original assignee: Man Diesel & Turbo, Filial Af Man Diesel & Turbo Se, Tyskland
Priority date: 2010-12-11
Filing date: 2011-12-09
Publication date: 2012-06-14
Also published as: JP2013545028A; DE102010054206B4; CN103370523A; JP5760094B2; CN103370523B; DE102010054206A1; KR101577677B1; KR20130101088A

Abstract

The invention relates to an internal combustion engine, in particular a large two-stroke diesel engine, comprising at least one combustion chamber (2) delimited by a cylinder (1) and a piston (3) interacting with a crankshaft, said combustion chamber comprising at least one combustion gas outlet (20; 120; 320; 420), which is formed between a valve disk (8; 108; 308) of an exhaust valve (9; 109; 309) and an associated disk seat, and at least one charge air inlet (4). The exhaust valve (9; 109; 309) can be actuated between an open position and a closed position. The combustion gas outlet (20; 120; 320; 420) is connected to at least one outlet channel (11) and to at least one combustion gas draw-off duct (18; 118a, 118b; 318, 318a; 418, 418a), for example in order to recirculate part of the combustion gas generated during combustion to the charge air inlet (4). The invention further relates to an exhaust valve (9; 109; 309) and to a cylinder head for such an internal combustion engine. The invention is characterized by a throttle device (10; 110; 310) which is fastened to the exhaust valve (9; 109; 309) or integrally molded as part of the exhaust valve (9; 109; 309) and by means of which the combustion gas is drawn off in a predetermined way. The invention further relates to a method for producing an internal combustion engine, to a method for operating an internal combustion engine, and to a use for an internal combustion engine.

Description

Internal combustion engine, exhaust valve and cylinder head therefor, as well as manufacture, operation and use of an internal combustion engine

The invention relates to an internal combustion engine, in particular a two-stroke large diesel engine, with the features of the preamble of claims 1, according to the preambles of claims 13 and 19 an exhaust valve and a cylinder head for such an internal combustion engine, according to the preamble of claim 20, a method for producing a such internal combustion engine, according to the preamble of claim 26, a use of such an internal combustion engine and according to the preamble of claim 27, a method for operating such an internal combustion engine.

In generic combustion engines, a fuel gas recirculation is known to pressurize the combustion chamber or the combustion chambers of the internal combustion engine supplied charge air with recirculated fuel gas. This is to reduce the nitrogen oxide (NOx) emissions. The charge air should therefore in addition to pure purge air from the environment, which precompressed and optionally pretreated, such as. dried, filtered or tempered, may also contain a component of another purge gas, for example a mixture of purge air and recirculated fuel gas. The charge air can then in addition to purge gas and / or pure purge air also contain other components, such as evaporated natural gas.

In order to recirculate the fuel gas into the combustion chamber, it is known, for example, to mix the purge air with the recirculated fuel gas and to purge the combustion chamber with this mixture via one or more common inlets, for example inlet slots. It is also known to introduce the recirculated fuel gas of the combustion chamber on the one hand and the remaining charge air portion on the other hand via separate inlets into the combustion chamber, so that the charge air forming mixture forms only in the combustion chamber. The present invention can be combined with all known types of fuel gas return introduction into the combustion chamber. German patent application DE 10 2005 057 207 A1 already discloses a generic internal combustion engine in which, in addition to an outlet valve which connects or separates the combustion chamber from the outlet channel, a separate, second outlet valve is provided which connects the combustion chamber to the recirculation line or separates from it. This structure is relatively expensive.

Furthermore, European Patent Application EP 2 151 569 A1 shows an internal combustion engine in which a recirculation line branches off in the exhaust passage downstream of the outlet valve, which can be opened or closed in the outlet passage via a second valve arrangement provided on the valve stem of the outlet valve and an associated valve receptacle. For example, a sleeve provided with circumferential slots on the valve stem of the outlet channel is provided for this purpose. The valve receptacle, which is arranged fixedly in the outlet channel, likewise has a sleeve with slots which covers the branch to the recirculation line. Characterized in that the exhaust valve and thus the valve stem are constantly rotated via a twisting mechanism to reduce uneven running of the valve seats, the branch can be opened and closed in the recirculation line. Although there is no need for a second, separate valve to open and close the recirculation line, the timing of the opening frequency and phase determined by the twisting mechanism on the engine operating cycle and the phase suitable for the recirculation phase during the engine cycle appear difficult.

Furthermore, from Japanese Patent Application JP 6 241 127 a four-stroke engine is known in which the outlet valve downstream outlet channel branches off a recirculation line, which is opened and closed via a separate valve, this valve is also designed as a throttle valve for the outlet and thus at opening the recirculation line throttles the flow through the outlet channel. The Recirculation valve outlet line throttle valve remains during the entire Spülhubs in the outlet channel throttling and the recirculation line opening position. Finally, from DE 10 2008 058 612 A1 an internal combustion engine is known, in which a recirculation line branches off only in the exhaust passage downstream of the outlet valve, which is also opened and closed here with a separate valve. In one embodiment, a throttle device which has a deflectable flap is provided in the outlet channel downstream of a region downstream of the recirculation line. The flap is opened by a pressure surge which results when the main outlet valve is opened and closed by a biasing spring when the pressure drops far enough. This solution is relatively expensive in terms of the timing of the exhaust valve, the throttle device and the valve upstream of the recirculation line and the entire structure, also with respect to the adjustment of the biasing force of the spring over which the throttle device is closed.

On this basis, it is an object of the present invention to provide an internal combustion engine, an exhaust valve and a cylinder head therefor, and to provide a method of operating such an engine with which as little as possible blended with fresh air fuel gas tapped at a high pressure level for recirculation or for other purposes can be. Furthermore, an innovative use and a manufacturing method for the found internal combustion engine should be specified.

This object is achieved with regard to the internal combustion engine having the features of claim 1, with regard to the exhaust valve having the features of claim 13, with regard to the cylinder head having the features of claim 19, with regard to the manufacturing method having the features of claim 20, with regard to use with the features of the claim 26, and in terms of the method for operating the internal combustion engine with the Features of claim 27.

According to the invention, a throttling device attached to the outlet valve or integrally formed with the outlet valve is provided which prevents the fuel gas from flowing into the outlet channel or at least throttles it more than in one in a fuel gas discharge opening region of the outlet valve extending from the closed position of the outlet valve to a desired opening degree from a larger degree of opening than the desired degree of opening to the open position reaching Abgasabfuhröffnungsbereich the exhaust valve, in which the throttle device, the flow of fuel gas into the outlet preferably preferably not or at least less throttled than in the Brenngasabzapföffnungsbereich the exhaust valve. The throttle device and a branch of the fuel gas drainage channel located on the outlet side or in the vicinity of the exhaust gas outlet controlled via the outlet valve are arranged with respect to one another such that the throttle device preferably does not throttle or at least substantially restricts the inflow of fuel gas into the fuel gas drainage channel in the fuel gas tapping opening region. In the Brenngasabzapföffnungsbereich the exhaust valve releases a relatively narrow annular gap and blocked with its throttle assembly ultimately leading into the environment outlet or narrowed at least in the diameter or flow cross-section. The Brenngasabzapfkanal is released, however. As a result, the very high pressure of the fuel gas in the combustion chamber, which is still very high at the beginning of the opening process of the outlet valve, is first converted into a flow passing through the annular gap at the outlet valve at high speed and thus with a high dynamic pressure. This flow is then in turn converted by the outlet channel occluding or at least flow cross-section reducing or throttling throttle device in a dynamic pressure, so that the fuel gas at high pressure in the same time not blocked by the throttle device or at least only slightly obstructed Brenngasabzapfkanal flows.

At the same time, in the period of the initial fuel gas bleed opening portion of the exhaust valve (when opening the exhaust valve) is pure or at least largely free of purge air fuel gas in the combustion chamber, and not a mixture of fuel gas and charge air, as may be present in the period of Abgasabfuhröffnungbereichs the exhaust valve. It depends on the initial opening period of the exhaust valve particularly and not so much on the phase at the end of the closing process, since only during the piston stroke down the pressure of the fuel gas is high enough to the fuel gas in the case of recirculation of the fuel gas tapped to Combustor inlet side without intermediate pump attributed to the charge air inlet. Depending on the timing of the exhaust valve thus passes only completely or at least relatively pure fuel gas in the Brenngasabzapfkanal, which may be the recirculation line in the case of tapping the fuel gas for a fuel gas recirculation into the combustion chamber. The during the period of Abgasabfuhröffnungsbereichs the exhaust valve (at a larger opening degree of the exhaust valve) present fuel gas-charge air mixture is, however, completely or at least for the most part in the then unthrottled or at least only weaker throttled exhaust duct discharged and not at all or only to a small Part in the Brenngasabzapfkanal or, in the case of fuel gas recirculation, in the recirculation line.

It is particularly advantageous in terms of a technically simple, because always synchronous to the exhaust valve clocking the fuel gas tap for the recirculation of the fuel gas to the inlet side of the combustion chamber or for other purposes and in terms of a simple structure and easy conversion of existing engines and engine concepts, in that the throttle device is formed integrally with the outlet valve or at least mounted on the outlet valve. Also, the desired Opening degree of the exhaust valve, to which the Brenngasabzapföffnungsbereich rich to be influenced by the shape of the exhaust valve or the molded or attached thereto throttle device and is not tied to the pressure surge occurring when opening the exhaust valve.

If one has an exhaust valve designed according to the invention, it is sufficient in many cases with existing engines to exchange only the exhaust valve or the exhaust valves in order to be able to tap fuel gas according to the invention. This is especially true in throttle devices, which only throttle the exhaust duct and should not completely close. If, however, the throttle device is to completely close the outlet channel, then it may be necessary to rework corresponding contact surfaces on the outlet channel, which must align well with the valve stem. In this case, or if there is no Brenngasabzapfkanal in the cylinder head installed on the engine, the replacement of the entire existing cylinder head by a cylinder head formed according to the invention may be advantageous. In particular, in these cases in which an existing internal combustion engine to be converted to fuel gas tap or fuel gas recirculation, the manufacturing method of the invention is advantageous.

According erfindemäß a method for tapping fuel gas to a running internal combustion engine, in particular a two-stroke large diesel engine, and in particular for purposes of fuel gas recirculation provided, the internal combustion engine having at least one limited by a cylinder and a cooperating with a piston piston combustion chamber, the at least one in each case between a valve disc of an exhaust valve and an associated plate seat formed fuel gas outlet and at least one charge air inlet has. The fuel gas outlet is connected to at least one outlet channel and at least one Brenngasabzapfkanal, for example, to return a portion of a resulting combustion fuel gas to the charge air inlet. In this case, the exhaust valve is actuated between an open position and a closed position, wherein in the fuel gas scavenging port area of the exhaust valve, an inflow of fuel gas into the exhaust passage is prevented or at least throttled more largely via a throttle device attached to the exhaust valve or integrally formed with the exhaust valve than in an exhaust exhaust port area of the exhaust valve from a larger opening degree to the open position. In the Brenngasabzapföffnungsbereich the influx of fuel gas into the Brenngasabzapfkanal by the throttle device, however, preferably not at all or at least not significantly throttled. The inventively attached to the exhaust valve or integrally molded with the exhaust throttle device has in particular in a two-stroke engine with fuel gas recirculation advantages. Thus, labor losses can be avoided by the fact that the exhaust valve can open later than conventional two-stroke engines with fuel gas recirculation, where usually relatively far before driving over the intake air slots, the exhaust valve (or the separate recirculation outlet) must be opened to mix the fuel gas to be returned with the to prevent new incoming charge air. In order to allow an inflow of fuel gas into the Brenngasabzapfkanal it is not necessary according to the invention to open the exhaust valve before a piston position is reached in the downstroke, which max. 40 ° crankshaft angle above that piston position at which the opening of the inlet or the inlets (intake air slots) begins. In some cases, a later opening of the outlet valve may be advantageous, but in any case before an onset of flushing of the combustion chamber via the inlet or the inlets (inlet air slots). Also, the high pressure of the recirculation gas is particularly important here, because the charge air pressure must be relatively high. If the recirculation pressure is high enough, a pump can be dispensed with. It is particularly advantageous in this case if a non-return valve provided in the fuel gas evacuation passageway flows into the unthrottled exhaust gas valve located in the exhaust gas discharge opening region Outlet channel flowing fuel gas charge air mixture prevented by the prevailing on the Brenngasabzapfseite, higher pressure keeps the check valve against the incoming fuel gas-charge air mixture closed. The non-return valve in the fuel gas evacuation channel can also be an actively controlled check valve, in particular in the case of a camshaft-actuated outlet valve, in order to be able to better control the bleed-off fuel gas quantity. In an electronically controlled and not via the camshaft, but via a separate drive operated exhaust valve, the timing of the exhaust valve can be adjusted accordingly to control the amount of fuel gas tapped.

Alternatively or in addition to the measures described above, the throttle device may also be configured or the throttle device and the outlet-side branch of the recirculation line to each other arranged so that the throttle device in the Abgasabfuhröffnungsbereich the exhaust valve prevents the flow of fuel gas into the Brenngasabzapfkanal or at least throttles, whereby the same effect is achieved, namely, to prevent an influx of the fuel gas charge air mixture present in the period of the Abgasabfuhröffnungsbereichs in the Brenngasabzapfkanal.

In an advantageous development of the invention, the throttle device has a preferably projecting throttle projection from a valve stem of the exhaust valve, wherein the throttle projection is provided in a region of the valve stem which is fluid in the exhaust gas branch port of the fuel gas exhaust port when the exhaust valve is opened in the fuel gas exhaust port region downstream of the exhaust duct. Thus, while the exhaust valve is in the Brenngasabzapföffnungsbereich the flow through the exhaust passage is throttled and pumped or redirected due to the resulting at the throttle projection back pressure in the Brenngasabzapfkanal. In particular, when the throttle projection in the manner of a movable piston in a designed as an outlet cylinder portion of the exhaust passage at the inner circumference of the exhaust passage at least loosely, the fuel gas passes in the Brenngasabzapföffnungsbereich open exhaust valve without large volume or pressure losses in the Brenngasabzapfkanal. An additional pump in the recirculation line leading back to the inlet side, which serves as a fuel gas evacuation channel in the case of a fuel gas drawn off for recirculation purposes, can thus be dispensed with. If the exhaust cylinder in the outlet side branch of Brenngasabzapfkanals downstream downstream region in which the throttle projection is located in Brenngasabzapföffnungsbereich outlet valve, circular cylindrical, so usually provided in generic two-stroke diesel engines valve rotation mechanism, often with Umschaftpropellergestaltung the intermittent rotational movement of the valve ensures that it is maintained in the usual way.

In the above-mentioned advantageous development of the invention, the Brenngasabzapfkanal can branch off from the fuel gas outlet in the outlet channel. The throttle projection may be provided in a region of the valve stem which is located at approximately the height of the branch of the Brenngasabzapfkanals in the exhaust passage at Auslaßventil open in Abgasabfuhröffnungsbereich. In the region of the branch of the fuel gas scavenging duct, the outlet channel can then have a particularly circular diameter widening, so that the fuel gas flowing into the outlet channel can flow around the throttle projection in its position located at the level of the branch of the fuel gas scavenging passage when the exhaust valve is open in the exhaust gas discharge opening region. In this case, the diameter expansion is preferably so great that the inflow of fuel gas into the outlet channel is preferably not throttled, but at least so great that the inflow of fuel gas is throttled less than at Auslassventil open in Brenngasabzapföffnungsbereich or in the branch of Brenngasabzapfkanals fluidly downstream area located throttle projection.

On the other hand, it would also be conceivable to arrange the throttle projection in the region of the valve stem located near the valve disk which is located in the combustion chamber with the exhaust valve open in the exhaust gas discharge opening region, so that an inflow into the exhaust passage is possible through the annular passage formed between the throttle projection and the disk seat , In this case, the branch of the recirculation line is preferably arranged on the plate seat itself or in a region of the outlet channel adjoining directly to the plate seat. An excessively large stroke of the outlet valve is then not necessary in order to simultaneously remove a combustion projection located in the combustion chamber for the removal of the fuel gas. Air mixture sufficiently large opening degree of the exhaust valve to ensure and at the fuel gas in the Abzapföffnungsbereich open exhaust valve the throttle projection in the branch of the Brenngasabzapfkanals downstream flow region of the exhaust duct to move.

It is understood that the throttle projection flows around at least when in the Abgasabfuhröffnungsbereich open outlet valve and to divert the flow in the Brenngasabzapfkanal when opened in Brenngasabzapföffnungsbereich exhaust flow. Advantageously, the throttle projection therefore has no unfavorable for the flow conditions edges, but - at least on its front side, so on the side with which it faces the branch of the recirculation line in Brenngasabzapföffnungsbereich - a hyperbolas curved surface to at in Brenngasabzapföffnungsbereich open outlet valve in to divert the combustion gas flowing into the area of the outlet channel upstream of the throttle projection into the fuel gas discharge channel branching laterally from this region of the outlet channel.

According to a further advantageous development of the invention, the outlet channel has a fuel gas outlet downstream of the fuel gas outlet Outlet cylinder, at the outer periphery of at least one outlet conduit and at least one Brenngasabzapfkanal branches off. In this case, the branch of the outlet line is provided downstream of the branch of Brenngasabzapfkanals. The throttle device may further comprise a slide which is predominantly axially slidably received in the outlet cylinder and which is connected to the outlet valve in such a way that it covers the branch of the outlet line at least in sections when the outlet valve is open in the fuel gas scavenging port area and the branch is open when the outlet valve is open in the exhaust gas removal opening area the Brenngasabzapfkanals.

It is advantageous, on the one hand, that not only the inflow into the outlet line is obstructed, or at least obstructed, by the outlet valve located in the fuel gas discharge opening region, but also the inflow of fuel gas and air mixture into the fuel gas evacuation channel or the return flow of fuel gas collected there into the outlet cylinder with exhaust valve opened in the exhaust gas discharge port area.

As mentioned earlier, the slide does not necessarily have to work completely close to the inner circumference of the outlet cylinder. It does not matter if between gas and Auslasszylinderwand some gas leaking, as long as the essential effect of the slide is satisfied as a throttle in the exhaust port at befindlichem in Brenngasabzapföffnungsbereich exhaust valve and advantageously as a throttle at the branch of Brenngasabzapfkanals in Abgasausfuhr- opening range open exhaust valve.

In terms of the above-mentioned functionality of the valve rotation mechanism usually provided, it is advantageous if the slide is designed as a circular cylindrical sliding sleeve and the outlet cylinder is also circular cylindrical. It should be noted, however, that in the case of exhaust valves without such a valve rotation mechanism, completely different geometries would also be conceivable. The slide or the sliding sleeve can be connected for example via radial struts with the valve stem of the exhaust valve. However, it would also be conceivable to design the sliding sleeve as a tube extending from the side of the valve disc facing away from the combustion chamber, which tube is provided in the region near the valve disc with passage openings for the flow.

In this case, a plurality of outlet lines branching off from the outlet cylinder or an outlet line with a plurality of branches distributed over the circumference of the outlet cylinder may preferably be provided in order to convey the inflow of the fuel gas / charge-air mixture with the outlet valve open in the exhaust-gas discharge opening region. Alternatively or additionally, the outlet line may also extend annularly around the outlet cylinder and open in an annular manner towards the outlet cylinder or have a branch opening in an annular manner towards the outlet cylinder.

Just as in the development with a throttle projection which is located in the outlet channel in the exhaust gas discharge opening region open exhaust valve, which then there is a diameter extension is provided to allow flow around the throttle projection, can throttle in the advantageous development with the slide or sliding sleeve. or closable outlet / Brenngasabzapfleitung the throttle device, namely, the throttle projection or the slider or the sliding sleeve be relatively far away from the combustion chamber arranged in the outlet channel. The throttle device is then not exposed to high thermal load and can therefore be relatively cheap, in the case of the throttle projection, for example, hollow. The branch of the Brenngasabzapfkanals is located in this case relatively far from the combustion chamber, so that no thermally highly loaded, thin material web between the branch of Brenngasabzapfkanals and the combustion chamber inner wall exists. On the other hand, it must be provided a certain size for the exhaust cylinder, within which the branch of Brenngasabzapfkanals and the displacement of the throttle device are housed. Therefore, the development may also be advantageous with a throttle projection located in the exhaust gas removal region in the combustion chamber and a fuel gas drainage channel branching off in the vicinity of the combustion chamber outlet or plate seat. In addition, thus a more direct and thus lossless inflow of the fuel gas can be achieved in the Brenngasabzapfkanal. Even further in this direction is a third advantageous development of the invention, in which the outlet channel also identifies a fuel gas outlet downstream, preferably circular cylindrical outlet cylinder, which, however, may be much shorter than in the previously discussed developments with such an outlet cylinder. Because the exhaust cylinder has here only on the side facing away from the combustion chamber of the valve disk in the axial direction of the valve stem record in the form of the cross section of the exhaust cylinder, if the exhaust valve is closed or opened in Brenngasabzapföffnungsbereich, then closed the outlet or at least the inflow the outlet channel is throttled. The Brenngasabzapfkanal branches off in a branching region located radially outside the stage (ie in the region of the plate seat of the valve disk), which is covered by the side of the valve disk facing away from the combustion chamber when the outlet valve is closed. The fuel gas bleed passage is thus disconnected from the combustion chamber when the exhaust valve is closed.

Preferably, however, the branching region is located in the region radially adjoining the step or at least in the vicinity of the outer circumference of the step, so that the plate seat, on which the side of the valve disk facing away from the combustion chamber is seated with the outlet valve closed, extends radially further outward than the branch area and thus a reliable closing of the combustion chamber outlet with the outlet valve closed is guaranteed.

An advantage of this development is in particular that the structural complexity of the throttle device is particularly low. Only the rear side of the valve disk has to be slightly extended by the step and, if a plant of the stage is provided on the outer circumference of the exhaust cylinder, the inner peripheral surface of the exhaust cylinder must be correspondingly finely machined and be well aligned with the valve stem axis. The pre- or secondary order of the inlet or the branch of the recirculation line with respect to the branch or the inlet of the outlet channel, wherein the branch of Brenngasabzapfkanal opens directly to the combustion chamber, proves to be advantageous from the viewpoint of an optimized fuel gas inflow into the Brenngasabzapfkanal , On the other hand, occurs in the region of the branch of Brenngasabzapfkanals here a high heat load, in particular in a thin material web of the combustion chamber wall between the combustion chamber and the Brenngasabzapfkanal. In order to ensure adequate cooling here, a coolant line provided in the material of the combustion chamber wall, in particular in the material between the plate seat and the fuel gas discharge channel, is therefore advantageous in the region of the fuel gas outlet.

If the fuel gas tapping channel expands annularly toward the combustion chamber or branches off from the fuel gas outlet via a branch opening in an annular manner towards the outlet cylinder, then the coolant line is preferably circumferential at least in sections. The ring-opening branch is advantageous for collecting the fuel gas to be conveyed into the fuel gas evacuation channel, for which purpose the branch can preferably open into the material of the combustion chamber wall in a bead-like manner.

Advantageous embodiments of the invention will be explained below with reference to the accompanying drawings. Show it:

1 is a schematic diagram of an internal combustion engine according to a first embodiment of the invention;

FIG. 2 is a partial sectional view of the combustion chamber outlet of the internal combustion engine shown in FIG. 1 with the exhaust valve closed; FIG.

Fig. 3 is a view corresponding to FIG. 2 in the

Fuel gas scavenging port area open exhaust valve;

4 is a sketched view of the area of the combustion chamber outlet according to another embodiment of the invention with the exhaust valve opened in the fuel gas scavenging port area;

FIG. 5 shows a view corresponding to FIG. 4 with the outlet valve open in the exhaust gas discharge opening region; FIG.

6 shows a schematic view of the region of the combustion-chamber outlet according to a further embodiment of the invention with the outlet valve closed;

Fig. 7 is a view corresponding to FIG. 6 in the

Fuel gas bleed port area open exhaust valve;

Fig. 8 is a Figs. 6 and 7 corresponding view at in

Exhaust gas discharge port region of opened exhaust valve;

FIG. 9 shows a schematic view of a combustion chamber outlet region slightly modified in comparison with the embodiment shown in FIGS. 6 to 8; FIG. 10 is a graph with plotted over the crank angle pressure curves.

and Fig. 11 is a diagram with applied over the crank angle flow cross sections.

Main field of application of the present invention are two-stroke large diesel engines, as used for example as marine propulsion. The basic structure and the mode of action of such arrangements are known per se. Frequently, a portion of the exhaust gas is to be returned to the reduction of NO _x emissions in the working space 2, ie recirculated. In this so-called recirculation gas, it is intended to simplify the control and ensure exact metering as pure as possible fuel gas, ie not diluted by purge gas exhaust gas.

1 shows an example of an internal combustion engine with fuel gas recirculation, which is developed according to an embodiment of the invention. However, the invention is not limited to the construction of the recirculation device shown purely by way of example in FIG. Also, different, designed according to the present invention exhaust valves and cylinder heads can be used, as is apparent from the further figures 2 to 9 by way of example. The invention is also not limited to engines with fuel gas recirculation, but can also be used to tap fuel gas for other purposes. Therefore, in the following, when referring to a "recirculation port area" of the exhaust valve, it means the "fuel gas exhaust port area" in an internal combustion engine with fuel gas recirculation and the indication "recirculation line" replaces the more general specification "fuel gas exhaust port". However, the described embodiments of the invention can also be used if the fuel gas for other purposes than for fuel gas recirculation tapped, or should be removed.

In the figure 1, a cylinder 1 of an internal combustion engine is indicated, which may have a plurality of cylinders arranged in series. Each cylinder 1 contains one Combustion chamber 2, the downwardly by a manner not shown via a piston rod, a crosshead and a connecting rod with a crankshaft cooperating, reciprocally movable piston 3 is limited. In the lower part of the cylinder 1 air inlet slots 4 are provided, which are run over by the piston 3 and in this way up and down. The air inlet slots 4 of each cylinder 1 communicate with an associated supply channel 5, which is connected to a continuous through all cylinders, can be acted upon with charge air manifold 6. The inlet slots 4 accordingly act as air inlets, via which the combustion chamber 2 can be acted upon with combustion air.

In the area of the cylinder cover which delimits the combustion chamber 2 upwards, an outlet valve 9 is provided, via which a fuel gas outlet 20 can be opened and closed. There may also be provided a non-illustrated fuel injection device.

The fuel gas outlet 20 is connected to an outlet channel 11. The exhaust ports 11 of all cylinders are normally connected to a common exhaust manifold 12 for all cylinders. From this goes from an exhaust pipe 13, which supplies the turbine 14 of an exhaust gas turbocharger 14, 15 with exhaust gas. The turbine 14 drives a compressor 15, which feeds compressed air via a scavenging air line 16 into the charge air distributor pipe 6. In the scavenging air line 16, a scavenging air cooler 17 may be arranged. The exhaust gas leaving the turbine 14 is discharged into the environment. In order to keep the NOx content of this exhaust gas as low as possible, a portion of the resulting in the combustion in the combustion chambers 2 gas directly or indirectly returned to the combustion chambers 2 (recirculated). For this purpose, a recirculation line 18 is provided, which branches off in the region of the fuel gas outlet 20 and opens into a recirculation gas collecting chamber 19 which extends through all cylinders 1 and which in turn is cooled by an optional treatment unit 21 for cooling and / or cleaning and / or filtering taken recirculation gas is connected to a line section of the recirculation line 18 to the charge air manifold 6. The recirculation line 18 is thus ultimately connected to the inlet slots 4 acting as charge air inlets.

In the arrangement on which FIG. 1 is based, the recirculation gas is admixed with the purging air or the purging gas and supplied to the combustion chambers 2 as charge air, i. supplied indirectly. For this purpose, the recirculation line 18 opens into the charge air manifold 6. The confluence of the recirculation line 18 could also be upstream of the radiator 17, as indicated in Figure 1 by a broken line. In such a case, a separate cooling of the recirculation gas could be omitted.

The pressure of the withdrawn from the combustion chambers 2 and fed into the recirculation line 18 recirculation gas is higher than the scavenging air pressure in the scavenging air line 16 so that there is an automatic flow and an additional unit for increasing the pressure in the recirculation line 18 is not required. In order to reliably prevent a backlash into the recirculation line 18 in the event of short-term pressure peaks in the charge air, a check valve in the recirculation line 18 can be provided, for example, in the region between the charge air manifold 6 and the recirculation gas collecting space 19, which opens to the combustion chamber inlet side. Furthermore, in the region between the recirculation gas collecting space 19 and the respective combustion chamber 2, in each case a check valve 23 may be provided in the recirculation line 18, which opens to the combustion chamber inlet side. As a result, it can be ensured at the same time that fuel gas can flow through the recirculation line 18 only if the pressure on the side of the fuel gas outlet 20 is higher than on the side of the recirculation gas collecting space 19 and no fuel gas collected there as recirculation gas flows back when the pressure on the part of the fuel gas Outlet 20 is lower than on the side of the recirculation gas collecting space 19th

As already mentioned, the pressure of the fuel gas withdrawn and recirculated from the combustion chambers 2 is higher than the charge air pressure, so that an additional unit, such as e.g. a pump or a compressor is not required. The inventively provided throttle device contributes significantly to this.

There are various variants of fuel gas recirculation systems known, wherein the fuel gas recirculation system shown in Figure 1 is listed here purely by way of example. For example, some elements comparable to the mentioned elements may be present multiple times in order to ensure parallel operation. Also, some of the elements shown may be divided into functionally separate, series-arranged units to achieve the desired functionality in the operation of the subject engine. Further, such a system may form the core of an extended system having, for example, further elements downstream or upstream of the turbine 14 to further utilize energy contained in the exhaust gas or to purify the exhaust gas prior to its ultimate discharge into the environment. Also, the air flow upstream / downstream of an element such as the compressor 15 may be subjected to further treatment by devices not shown in FIG. This airflow can also be admixed with an ingredient that differs from pure ambient air, so that instead of pure purge air, a purge gas with another gaseous, flammable or non-combustible ingredient is present before the recirculated fuel gas is also buried in the gas stream provided for rinsing the cylinder. The final gas mixture intended for rinsing the cylinder may have a very wide range of compositions and is referred to as "charge air." Of course, the present invention may be applied to all such fuel gas recirculation systems.

Figures 2 and 3 is a first embodiment of a Fuel gas outlet with a throttle device 10 of the type described above can be seen. FIG. 2 shows the combustion chamber 2 in a state separated from the outlet channel 11 by the closed outlet valve 9. By dashed line, however, a fully open position of the exhaust valve 9 is indicated. The outlet valve 9 thus moves with clocked on the movement of the piston 3 timing up and down, as indicated by the thick arrow with double point.

The outlet valve 9 in this case has a valve disk 8, which rests in the closed position on a plate seat and thus the fuel gas outlet 20 closes and 9 releases the fuel gas outlet 20 during downward movement of the valve. The valve plate 8 is attached to a valve stem 7, which in turn is mounted in the cylinder head in a known manner and usually via a - not shown - camshaft is driven, with other valve actuators would be conceivable, especially after the so-called electronic Ventilsteurungsprinzip without mechanical coupling between Crankshaft and valve stem, such as. the recent emergence, electronic valve direct control with a valve actuation by electromagnet or the like.

At the valve stem 7, a rotationally symmetrical throttle projection 10 is provided, specifically at a position at which the throttle projection 10 with the exhaust valve 9 closed (FIG. 2) and up to a certain desired degree of opening (FIG. 3) in a branch of the recirculation line 18 from the outlet channel 11 downstream arranged region is arranged. In this area, between the position of the exhaust valve 9 shown in FIG. 2 and FIG. 3, which corresponds to the recirculation opening area of the exhaust valve 9, the throttle projection 10 rests with its outer circumference on an inner circumference of a circular cylindrical portion of the exhaust duct 1 1 and closes the exhaust duct 11 thereby at least substantially for the effluent from the combustion chamber 2 fuel gas, said closure is not necessarily absolute must, as long as the essential for the invention throttle effect is achieved.

The fuel gas flowing out of the combustion chamber 2 in this phase is therefore, as indicated by the arrows in FIG. 3, directed in the direction of the recirculation line 18, including the hyperbolic or rounded surface on the side of the throttle projection 10 facing the combustion chamber 2 circular-shaped around the outlet channel 11 in the region of the branch of the recirculation line 18 circumferential diameter widening 22 also contribute with rounded edges.

If the outlet valve 9 then moves from the position of the desired opening degree shown in FIG. 3, which defines the upper limit of the recirculation opening area, further downwards into its fully open position (indicated by a dashed line in FIG. 2), the throttle projection 10 comes within the range of Branch of the recirculation line 18 and thus the diameter widening 22 and there can be flowed around by the gas flowing out of the combustion chamber 2 through the then completely open fuel gas outlet 20, which can thus be discharged through the outlet channel 11.

The embodiment shown here is advantageous in several respects. Thus, during the initial opening phase between the position shown in Figure 2 and Figure 3 in Figure 3, ie in the recirculation or Brenngasabzapföffnungsbereich in the combustion chamber 2 pure or nearly pure fuel gas, since in this phase, the air inlet slots 4 or not at least not far have been run over, this fuel gas also has a high pressure. The fuel gas flowing into the recirculation line 18 thus has the desired properties for recirculation, namely an overpressure relative to the pressure of the gas present in the purge system, namely the purge gas or the purge air to which the fuel gas flowing into the recirculation line 18 is to be admixed, so that the check valve 23 in the recirculation line 18 opens, as in FIG Figure 3 indicated. On the other hand, the fuel gas also has the desired low oxygen concentration, which is increased only after opening of the air inlet slots 4 and the charge air. In the subsequent Abgasabfuhröffnungsphase, ie at more open exhaust valve 9, as indicated in Figure 2 by dashed line, the piston 3, however, the Charging air inlet slots 4 has already run over, so that in the combustion chamber 2 is a gas mixture with an unfavorable for the recirculation, low pressure , This gas mixture now passes through the wide open fuel gas outlet 20 into the inlet region of the outlet channel 11 and there into the region of the diameter widening 22, in which the throttle projection 10 is located. A flow around the throttle projection 10 is thus possible, without causing a significant dynamic pressure is exerted on the gas flowing out of the combustion chamber 2. The gas flows out of the combustion chamber at all because the pressure in the exhaust gas collecting pipe 12 is, in principle, lower than the charge air pressure. The gas mixture can thus not enter the recirculation line 18 during the Abgasabfuhröffnungsphase or the check valve 23 does not open, but flows around the throttle projection or body 10 in the direction of the Abgassammeirohr 12 out and is thus excluded from the recirculation.

FIGS. 4 and 5 show a further embodiment of the invention in which a somewhat modified outlet valve 109 and a modified branch region of recirculation lines 118a, 118b are used from the outlet channel 11, but the combustion chamber 2 itself is opposite that in FIGS. 1 to 3 can be unchanged, which incidentally also applies to the other, shown in Figure 1 engine components. Here, a circumferential throttle projection 110 is also provided on the valve stem 107. However, this is directly downstream of the valve disk 108. At the same time there is the branch of the recirculation line or in the case The fuel gas outlet 120 is thereby formed in the Rezirkulationsöffnungsstellung shown in Figure 4 of the exhaust valve 109 through the back of the valve disk 108 and the valve disk seat on the combustion chamber wall, whereas the Fuel gas outlet 120 is formed in the exhaust gas discharge opening position of the exhaust valve 109 shown in Figure 5 between the rear and radial outer side of the throttle projection 110 and the valve disk seat.

As in the case of the first embodiment of the invention, the throttle projection 110 closes at least substantially in the region of the outlet channel 11 downstream of the branches 118a, 118b of the recirculation line, so that the fuel gas flowing out of the combustion chamber 2 is in the recirculation opening region of the outlet valve is passed into the recirculation lines 118a, 118b, as indicated in Figure 4 by arrows. In the individual recirculation lines or in a recirculation line section into which the individual recirculation lines 118a, 118b open, a check valve can be provided in each case, as shown in FIGS. 4 and 5, this check valve in FIG. 4 in the recirculation line 118b merely for reasons of space not shown. The check valves only allow an inflow of recirculation gas or fuel gas into the recirculation collection container 19 if this fuel gas has a higher pressure than the recirculation gas collected in the collection container 19.

On the other hand, if the exhaust valve 108 has a larger opening degree or is located in the exhaust gas discharge opening region, then the circumferential throttle projection 110 no longer seals the exhaust duct 11, so that the then present gas flows into the exhaust duct 11 and from there into the exhaust gas collecting pipe 12, as indicated in Figure 5 by arrows. It should be noted that in terms of improved flow of the fuel gas into the Recirculation not only two recirculation lines 118a, 118b may be provided, but also several, over the circumference of the circular cylindrical outlet channel 1 1 distributed recirculation lines. Therefore, it is also possible to provide a circumferential, inner-walled peripheral recess from which these recirculation lines 118 exit.

Finally, FIGS. 6 to 8 show a further embodiment of the invention when the outlet valve 308 is closed (FIG. 6), when the outlet valve (FIG. 7) is open in the recirculation area, and when the outlet valve (FIG. 8) is open in the exhaust gas removal area.

In this embodiment, the throttling device consists of a step 310 projecting from the rear side of the valve disk 308, which in the recirculation opening region extending from the closed position of the outlet valve 309 shown in FIG. 6 to the position of the outlet valve with the desired degree of opening shown in FIG. 7, the outlet channel 11 closes, however, the recirculation line 318, or their annular around the outlet channel 1 1 circumferential branch 318a or its annular circulating around the outlet channel 11 inlet 318a releases for the inflow of combustion gas flowing out of the combustion chamber 2 through the fuel gas outlet 320 fuel gas. In contrast, in the exhaust gas removal region shown in FIG. 8, the outlet valve 307 is displaced into the combustion chamber so far that the step 310 no longer abuts against the wall of the outlet channel 11 corresponding to the recirculation opening region, but releases the outlet channel 11. As explained above, a check valve may also be provided in the recirculation line 318 here.

In the present embodiment, since the gate 318a is disposed in the recirculation passage 318 directly at the outlet 320 of the combustion chamber 2, the material located between the combustion chamber wall and the recirculation passage 318 and the branch 318a, respectively, is subjected to a great heat load a little thinner Material web stands. In order to reduce this disadvantage, the embodiment of the invention shown in FIGS. 6 to 8 can be somewhat modified, as FIG. 9 shows. Here, a coolant channel 24 is provided in the standing between the combustion chamber side surface and the inlet 418a of the recirculation line 418 material web, which also leads around the outlet channel 1 1. At the same time, the collecting volume of the recirculation inlet 418a opening into the material and also the inlet area of the recirculation line 418 are moved a little further back from the combustion chamber into the material, so that a wider material web better withstands the high heat load than with the one in FIG Figures 6 to 8 shown embodiment of the invention. In addition, here at the valve stem 307 a known professional rotary vane ring 25 is designated, which leads over the passing gases to a valve rotation, which is intended to prevent premature wear of the exhaust valve 309 and the plate seat.

By way of example and purely quantitatively for an internal combustion engine according to the present invention, in FIG. 11, the course of the free flow cross section in the region of the purge gas inlets is shown in FIG. 11 as a function of the movement of the piston 3 through the curve b in ° CA to TDC (degree crank angle after top dead center) 4 forming inlet slots shown. The curve a, however, gives the course of the free flow cross-section in the region of the fuel gas outlet 20 again. With a solid line while the course is drawn at a camshaft driven exhaust valve 9, whereas with dashed line possible courses of the free flow cross-section in an electronically controlled and without mechanical coupling between the crankshaft and valve stem operated exhaust valve are indicated. The opening of the camshaft actuated exhaust valve 9 takes place according to curve a, for example at about 115 ° CA after TDC, ie 65 ° above the bottom dead center during the downward stroke. In an electronically controlled and actuated Exhaust valve may begin opening a little earlier, eg at about 110 ° CA after TDC, and then be interrupted to extend the fuel gas bleed opening area before then fully opening and driving the exhaust valve into the exhaust gas removal area.

The purge gas inlets 4 are opened according to curve b at about 135 ° CA after TDC (i.e., 45 ° above bottom dead center during the downstroke). Provided that the engine formed from the piston 3 and crankshaft is substantially symmetrical, the purge gas inlets 6 are closed during the upward stroke of the piston 3 at about 135 ° CA before TDC again. The closure of the outlet valve 9, which is often not controlled symmetrically to the top dead center, takes place somewhat later in the upstroke, so that the working space 2 is reliably purged with the outlet valve 9 open. Here, no fuel gas is removed, so there is no Brenngasabzapföffnungsbereich during the upward stroke of the piston, so that the control of the electronically controlled and actuated exhaust valve can be carried out in accordance with the normal camshaft actuated exhaust valve.

When the outlet valve 9 is opened, the escaping exhaust gas causes a pressure increase in the outlet channel 11. In FIG. 10, in the curve c, the profile of the pressure in the outlet channel 11 is determined as a function of the piston movement, i. over the crank angle, applied. It can be seen that when opening the outlet valve 9, the pressure in the outlet channel 1 1 increases abruptly. This leads to a pressure surge e which has one or more peaks and starts at approximately 1 15 ° CA after TDC. The pressure surge e is of relatively short duration and only extends over about 20 ° CA. The pressure surge e is therefore completed before the opening of the inlet slots 4. The opening of the purge gas inlets 4 would in any case lead to a final termination of the pressure surge e.

In the further curve d shown in FIG. 10, the pressure profile in the combustion chamber 2 is plotted against the crank angle. As the pressure in the Combustion chamber 2 is relatively high, applies here on the pressure associated with the abscissa for curve d a different scale than for curve c. Although the curves c and d intersect in FIG. However, this is only based on the different scale. If the same scales were used, the curves c and d would not intersect or only in the region of the pressure surge e. According to curve a (FIG. 11), the exhaust valve 9 is completely open from about 130 ° CA to TDC. Therefore, the pressure in the combustion chamber 2 and the outlet channel 11 after completion of the pressure surge e of about 150 ° CA to TDC to 180 ° CA after TDC is about the same. From about 160 ° CA after TDC, the purge gas inlets 4 are completely open according to curve b.

Accordingly, the pressure in the combustion chamber 2 and in the outlet channel 11 is only slightly less than the purge gas pressure, which is illustrated in Fig. 10 by the curve f, which represents the pressure in the purge system and was drawn on the same scale as the curve c. It can be clearly seen at e that the pressure in the outlet channel already substantially exceeds the pressure f in the flushing system shortly after opening the outlet valve 9, whereby a positive pressure difference is achieved, which is used according to the invention, the fuel gas in the Brenngasabzapfkanalsystem and continue to push into the fuel gas recirculation circuit ending with an inlet somewhere in the purge gas system. It should be noted that due to a larger volume which would be compressed directly downstream of the exhaust valve immediately after the Auslaßventilbetätigung, the shape of the curve c at e substantially flatter and only a lower maximum pressure value would be achieved if the inventive throttle device would not be present.

Here it is clearly shown at g that the purge gas pressure f for the purge is above the actual pressure in the outlet channel and in the following exhaust gas removal system. During this phase, when the scavenging inlets are open to the combustion chamber, therefore, there exists a positive pressure difference transmitted between the scavenging system and the exhaust evacuation system over the cylinder volume, so that the scavenging results in an entry of purge gas into the cylinder volume through the inlets a simultaneous expulsion of fuel gas through the open exhaust valve.

Modifications and modifications of the illustrated embodiments are possible without departing from the scope of the invention.

For example, the valve twisting mechanism is not mandatory for the function of recirculation control, but may also be provided in the embodiments illustrated in FIGS. 1-7. On the other hand, if such a twisting mechanism is missing, then the throttle device, be it in the form of a throttle disk, a sliding sleeve or the step projecting from the valve disk and the associated section of the outlet channel, can also have a completely different geometry. In the illustrated embodiments, however, the throttle plate, sliding sleeve or the projecting from the valve plate stage as well as the associated portion of the outlet channel is symmetrical in each radial direction to the valve axis.

Of course, the exhaust valves according to the invention in one piece, so in one piece or be mounted from several pieces, with other components can be attached thereto, such as the rotary vane wreath 25 or other components. It is crucial that the exhaust valve is always controlled and moved as a whole unit. Also, the cylinder head may be composed of individual components to form an assembly, wherein the components may be specially adapted to realize their respective function and / or interiors, such as the water cooling loop 24. Further, in all embodiments, actively controlled or passive check valves in the Brenngasabzapfkanal or the recirculation line may be provided. LIST OF REFERENCE NUMBERS

Cylinder (1)

Combustion chamber (2)

Piston (3)

Inlet slots (4)

Supply channel (5)

Distributor pipe (6)

Valve stem (7; 107; 307)

Valve disc (8; 108; 308)

Exhaust valve (9; 109; 309)

Throttle device (10; 110; 310)

Throttle projection (10; 110)

Throttle heel (310)

Outlet channel (11)

Exhaust gas collecting pipe (12)

Exhaust pipe (13)

Turbine (14)

Compressor (15)

Exhaust gas turbocharger (14, 15)

Charge air line (16) Intercooler (17)

Fuel gas bleed passage (18; 118a, 118b; 318, 318a; 418, 418a) recirculation gas collecting space (19)

Fuel gas outlet (20)

Recirculation gas treatment unit (21)

Diameter widening (22)

Check valve (23)

Water cooling pipe (24)

Valve vane ring (25)

Claims

I. internal combustion engine, in particular two-stroke large diesel engine, with at least one by a cylinder (1) and a cooperating with a crankshaft piston (3) combustion chamber (2), at least one each between a valve plate (8, 108, 308) of an exhaust valve And at least one charge air inlet (4), the outlet valve (9; 109; 309) being disposed between an open position and (9; 109; 309) and an associated disc seat; a closed position, and wherein the fuel gas outlet (20; 120; 320; 420) is connected to at least one exhaust duct (11) and at least one fuel gas exhaust duct (18; 118a, 118b; 318, 318a; 418, 418a) is, for example, due to a part of a combustion gas produced during combustion to the charge air inlet (4), characterized in that one of the exhaust valve (9; 109; 309) attached or integral with the exhaust valve (9; 309) formed throttle device (10; 1 10; 310) which prevents or prevents fuel gas from flowing into the exhaust passage (11) in a fuel gas scavenging port region of the exhaust valve (9; 109; 309) extending to a desired opening degree from the closed position of the exhaust valve (9; 109; 309) throttles at least more than in a reaching from a larger opening degree to the open position Abgasabfuhröffnungsbereich the exhaust valve (9; 109; 309), in which the throttle device (10; 110; 310), the inflow of fuel gas into the outlet channel (11) preferably not at all or at least less severely throttled, wherein the throttle device (10; 110; 310) and an outlet-side branch of the Brenngasabzapfkanals (18; 118a, 118b; 318, 318a; 418, 418a) are mutually arranged so that the throttle device (10; 310) in the Brenngasabzapföffnungsbereich the flow of fuel gas into the Brenngasabzapfkanal (18, 118a, 118b, 318, 318a, 418, 418a) preferably not at least or not significantly throttles.

An internal combustion engine according to claim 1, characterized in that the exhaust valve (9; 109; 309) is controlled so that it does not open before a piston position is reached in the downstroke which is at least 1 ° and at most 40 ° crankshaft angle above that piston position at which the opening of the charge air inlet (4) begins.

3. Internal combustion engine according to claim 1 or 2, characterized in that the throttle device and the outlet side branch of Brenngasabzapfkanals are arranged to each other so that the throttle device in the Abgasabfuhröffnungsbereich prevents the flow of fuel gas into the Brenngasabzapfkanal or at least throttles and / or a check valve in the Brenngasabzapfkanal is provided which prevents the flow of fuel gas into the Brenngasabzapfkanal in the Abgasabfuhröffnungsbereich or at least throttles.

4. Internal combustion engine according to one of the preceding claims, characterized in that the throttle device (10; 110) comprises a preferably projecting throttle projection (10; 110) projecting radially from a valve stem (7; 107) of the outlet valve (9); In the region of the valve stem (7; (1 1) is located, which is preferably formed in this area circular cylindrical.

5. Internal combustion engine according to claim 4, characterized in that the

Brenngasabzapfkanal (18) from the fuel gas outlet (20) spaced branches in the exhaust passage (11), the throttle projection (10) is provided in a region of the valve stem (7) located in the Abgasabfuhröffnungsbereich opened exhaust valve (9) is located approximately at the level of the branch of Brenngasabzapfkanals (18) in the outlet channel (11), and the outlet channel (11) in the region of the branch of Brenngasabzapfkanals (18) has a particular annular diameter expansion, so that the throttle projection ( 10) preferably does not at all or at least less severely throttles the flow of fuel gas into the outlet channel (11) when the outlet valve (9) is open in the exhaust gas removal opening region than in the outlet valve (9) opened in the fuel gas discharge opening region.

6.A combustion engine according to claim 4, characterized in that the throttle projection (1 10) is located in a region of the valve stem (107) located in the Abgasabfuhröffnungsbereich open outlet valve (109) in the combustion chamber (2), wherein the branch of the fuel gas evacuation channel (11a, 118b) is preferably located on the plate seat or in a region of the outlet channel (11) immediately adjacent to the plate seat.

7.Verbrennungsmotor according to claim 4, 5 or 6, characterized in that the diameter of the valve stem (7; 107) in the region of the throttle projection (10; 110) at least on the valve disc (8; 108) side facing the throttle projection (10; 1 10) with a curvature merges into the largest radial outer dimension of the throttle projection (10; 110), wherein the throttle projection (10; 110) is preferably rounded off at its radial outer edge.

8.Verbrennungsmotor according to one of claims 1 to 3, characterized in that the outlet channel has a fuel gas outlet downstream fluid outlet cylinder, at the outer periphery of at least one outlet and at least one Brenngasabzapfft branches, the branch of the outlet provided downstream of the branch of Brenngasabzapfkanals is, and wherein the throttle device comprises a slide slidably received in the exhaust cylinder, which is fixedly connected to the exhaust valve such that it at least partially in the branch line of the exhaust pipe at Auslassventil open in Brenngasabzapföffnungsbereich covers and preferably at exhaust gas discharge opening in the exhaust valve open the branch of Brenngasabzapfkanals.

9. Internal combustion engine according to claim 8, characterized in that the

Slider is designed as a circular cylindrical sliding sleeve, which is connected for example via radial struts with the valve stem of the preferably rotatable outlet valve, wherein the outlet cylinder is also circular cylindrical and preferably an outlet with multiple, distributed over the circumference of the outlet cylinder branches and / or an outlet with a annular opening to the exhaust cylinder opening of the outlet is provided.

10. Combustion engine according to one of claims 1 to 3, characterized in that the outlet channel (11) has a fuel gas outlet (420) downstream, preferably circular cylindrical outlet cylinder and the throttle device (310) on the combustion chamber (2) side facing away the valve disk (308) has a step (310), preferably in the axial direction of the valve stem (307) or at least with axial direction component, in the form of the cross-section of the exhaust cylinder closing or at least constricting the exhaust cylinder with exhaust valve (309) opened in the fuel gas exhaust port region, the fuel gas exhaust port (318, 318a, 418, 418a) branches off in a branching region located radially outside the step (310), which is covered with the outlet valve (309) closed away from the side of the valve disk (308) which faces away from the combustion chamber (2) and continues radially extends outward than the branching area, so there ss the Brenngasabzapfkanal (318, 318a; 418, 418a) is separated from the combustion chamber (2), the branch region preferably being in the region radially adjoining the step (310) or at least near the outer periphery of the step (310), and wherein the plate seat, on which the side of the valve disk (308) remote from the combustion chamber (2) is seated when the outlet valve (309) is closed, extending radially further outwards than the branching region.

11.Verbrennungsmotor according to any one of the preceding claims, characterized 418, 418a) branches off at the fuel gas outlet via a branch opening (22; 318a; 418a) which opens in an annular manner towards the outlet cylinder, which preferably opens into the material in a bead-like manner and / / or a Brenngasabzapfkanal (118a, 118b) is provided with a plurality of distributed over the circumference of the exhaust cylinder branches (118a, 118b).

12. Internal combustion engine according to one of the preceding claims, characterized in that in the region of the fuel gas outlet (420), in the material of the combustion chamber wall, in particular in the material behind the plate seat at least partially circulating coolant line (24) is provided.

An exhaust valve (9; 109; 309) for opening and closing a fuel gas outlet (20; 120; 320; 420) of a combustion chamber (2) of a combustion chamber (2) bounded by a cylinder (1) and a piston cooperating with a crankshaft An internal combustion engine, in particular a two-stroke large diesel engine, in particular according to one of the preceding claims, wherein the outlet valve (9; 109; 309) has a valve stem (7; 107; 307) via which it can be actuated between an open position and a closed position, and a valve plate (8; 108; 308) adjoining the valve stem to form, together with an associated disc seat, the fuel gas outlet (20; 120; 320; 420), characterized in that one of the exhaust valves (9; 109; 309 is provided (10; 110; 310) fixed or integrally formed with the exhaust valve (9; 109; 309), which is adapted to move in one of the closed position of the exhaust valve (9; 109; 309) to a m the desired opening degree reaching Brenngasabzapföffnungsbereich the exhaust valve (9; 109; 309) prevent or at least more strongly restrict the flow of fuel gas into the exhaust passage (11) than in an exhaust exhaust port area of the exhaust valve (9; 109; 309) reaching from a larger opening degree to the open position, in which the throttle device (10; 310), the inflow of fuel gas into the outlet channel (11) preferably not or at least less throttles.

14. An exhaust valve (9; 09) according to claim 13, characterized in that the throttle device (10; 1 10) protrudes radially from a valve stem (7; 107) of the exhaust valve (9), from the valve disk (8; 108). wherein the diameter of the valve stem (7; 107) in the region of the throttle projection (10; 1 10) at least on the valve disc (8; 108) facing side of the throttle projection (10; ) with a curvature in the largest radial outer dimension of the throttle projection (10; 110), and wherein the throttle projection (10; 110) is preferably rounded at its radially outer edge.

15. exhaust valve (309) according to claim 13, characterized in that the

Throttling device (310) on the side facing away from the combustion chamber (2) of the valve disk (308) has a preferably in the axial direction of the valve stem (307) or at least with axial direction component protruding step (310) and with a radially outwardly adjacent to the step (310) Area of the valve disc (308) on the side facing away from the combustion chamber (2) of the valve disc (308) is seated with the exhaust valve (309) closed.

16. An exhaust valve according to claim 13, characterized in that the throttle device comprises an axially movable in the exhaust cylinder, in particular on the inner circumference of the exhaust slidably received and spaced from the valve disc slider, in particular in the form of a circular cylindrical sleeve, which via radial struts with the valve stem of the exhaust valve connected is.

17.Auslassventil according to any one of claims 13 to 16, characterized in that on the valve stem (307) further comprises a valve vane ring (25) is provided.

18. Exhaust valve according to one of claims 13 to 17, characterized in that on the combustion chamber remote from the end of the valve stem a contactlessly readable identification mark is provided, which has at least one of the valve path until reaching the transition position between Brenngasabzapföffnungsbereich and Abgasabfuhröffnungsbereich corresponding axial extent, wherein the identification mark preferably extends over the entire circumference of the valve stem.

19. Cylinder head for an internal combustion engine, in particular according to one of claims 1 to 12, in particular for a two-stroke large diesel engine, with at least one by a cylinder (1) and a cooperating with a crankshaft piston (3) limited combustion chamber (2), wherein the cylinder head having a plate seat for a valve disk (8; 108; 308) of an exhaust valve (9; 109; 309) opening and closing the cylinder head at a fuel gas outlet (20; 120; 320; 420), the fuel gas outlet (20 120, 320, 420) is connected to at least one outlet channel (11) and to at least one fuel gas bleed passage (18; 118a, 118b; 318, 318a; 418, 418a), for example to form part of a combustion gas produced during combustion for charge air separation. Characterized in that an exhaust valve (9; 109; 309) according to any one of claims 13 to 18 is provided, wherein the throttle means (10; 110; 310) and an outlet side branch of the Bren ngasabzapfkanals (18; 118a, 118b; 318, 318a; 418, 418a) are arranged so that the throttling device (10, 110, 310) in the fuel gas scavenging port region preferably does not or at least does not flow the fuel gas into the fuel gas scavenging passage (18, 118a, 118b, 318, 318a, 418, 418a) significantly throttles, wherein preferably also a non-contact reader for the identification mark is provided.

20. A method for producing a two-stroke large diesel engine, in particular according to one of claims 1 to 12, which at least one by a cylinder (1) and a combustion chamber (2), which cooperates with a crankshaft, and which has at least one combustion gas each formed between a valve disk (8; 108; 308) of an exhaust valve (9; 109; 309) and an associated disk seat. Having exhaust (20; 120; 320; 420) and at least one charge air inlet (4), characterized in that an exhaust valve (9; 109; 309) is installed according to one of claims 13 to 18.

21. A method for producing a two-stroke large diesel engine, in particular according to one of claims 1 to 12, which at least one by a cylinder (1) and a cooperating with a crankshaft piston (3) limited combustion chamber (2) which at least one between each has a fuel gas outlet (20; 120; 320; 420) formed of a valve disk (8; 108; 308) of an outlet valve (9; 109; 309) and an associated disk seat and at least one charge air inlet (4), characterized in that a cylinder head according to claim 19 is installed.

22. The method according to claim 20 or 21, characterized in that the

Two-stroke large diesel engine is manufactured for the first time.

23. The method according to claim 20 or 21, characterized in that the

Two-stroke large diesel engine remains functional.

24. The method according to claim 23, characterized in that the installation of the exhaust valve (9; 109; 309) according to one of claims 13 to 18, another conventional exhaust valve is replaced or that by the installation of the cylinder head according to claim 19 another, Conventional cylinder head is replaced, so that a conventional two-stroke large diesel engine without the characterizing features of a claim from claims 1 to 12 is converted to a two-stroke large diesel engine according to one of claims 1 to 12.

25. Use of an internal combustion engine according to one of claims 1 to 12 in a construction used on the water, in particular a ship whose statutory operating permit from the statutory operating permit for Internal combustion engine depends.

26. A method for tapping fuel gas to a running internal combustion engine, in particular two-stroke large diesel engine, in particular according to one of claims 1 to 12, which at least one by a cylinder (1) and a cooperating with a crankshaft piston (3) limited combustion chamber (2) comprising at least one fuel gas outlet (20; 120; 320; 420) each formed between a valve disk (8; 108; 308) of an exhaust valve (9; 109; 309) and an associated disk seat; and at least one charge air inlet (4) wherein the exhaust valve (9; 109; 309) is actuated between an open position and a closed position, and wherein the fuel gas outlet (20; 120; 320; 420) is provided with at least one exhaust passage (11) and at least one Fuel gas bleed passage (18; 1 18a, 118b, 318, 318a, 418, 418a) is connected, for example, to a part of a combustion gas generated during combustion to the charge air inlet (4) due, characterized gekennzeic hnet that in one of the closed position of the exhaust valve (9; 109; 309) injecting fuel gas into the exhaust passage (11) via an exhaust valve (9; 109; 309) fixed to the exhaust valve (9; 109; 309) or integrally with the exhaust valve (9; ; 109; 309) throttle means (10; 110; 310) is prevented or at least throttled more than in an exhaust port opening area of the exhaust valve (9; 109; 309) reaching from a larger opening degree to the open position and the flow of fuel gas in the fuel gas scavenging port area preferably not at all, or at least not substantially throttled, into the fuel gas discharge duct (18, 18a, 18b, 318, 318a, 418, 418a) by the throttle device (10, 110, 310).

27. The method according to claim 26, characterized in that in the Abgasabfuhröffnungsbereich the influx of fuel gas in the Brenngasabzapfkanal via the throttle device and / or provided in the Brenngasabzapfkanal actively controllable or passive check valve prevents or at least throttled.

28. The method of claim 26 or 27, characterized in that in an electronically actuated exhaust valve, the control times of the throttle device are readjusted continuously.

29. The method of claim 26 or 27, characterized in that in a camshaft actuated exhaust valve, the tapped fuel gas quantity is controlled via an actively controllable check valve in the fuel gas tapping passage.