EP3551871A1

EP3551871A1 - Mixture formation device for a gas engine and gas engine

Info

Publication number: EP3551871A1
Application number: EP17804562.1A
Authority: EP
Inventors: Christian-B. KLÜTING; Frank Beger; Martin Kiel
Original assignee: Volkswagen AG
Current assignee: Volkswagen AG
Priority date: 2016-12-08
Filing date: 2017-11-28
Publication date: 2019-10-16
Also published as: RU2726984C1; US20200032722A1; WO2018104107A1; CN110023613A; DE102016123826A1; CN110023613B; US11181051B2

Abstract

The invention relates to a mixture formation device for an internal combustion engine operated with a burnable gas, preferably compressed natural gas CNG. The mixture formation device comprises a combination of a quantity regulator, a gas mixer, a flow-guiding element for pressure recovery, and a connection possibility for exhaust gas recirculation of the internal combustion engine. The mixture formation device according to the invention can empty a gas tank to a comparatively low pressure of approx. 2 bar, an excellent mixture formation being achieved over the entire range of speed and load range of the internal combustion engine. According to the invention, such a mixture formation device can reduce production costs as well as space requirements compared to known solutions. The invention also relates to an internal combustion engine operated with a burnable gas, particularly compressed natural gas (CNG), comprising such a mixture formation device in the intake tract thereof.

Description

description

Mixture forming device for a gas engine and gas engine

The invention relates to a mixture formation device for a combustion engine operated with a combustible gas and to an internal combustion engine in whose intake tract such a mixture formation device is arranged.

Internal combustion engines which are operated with a combustible gas, for example liquefied natural gas (LPG) or pressurized natural gas (CNG), are known from the prior art. Especially in pressurized natural gas (CNG), the challenge of putting the gas into the gas is the challenge

To promote combustion chambers of the internal combustion engine. Since gases compared to (quasi

incompressible) liquids have a significantly higher compressibility, such a gas can not with a conventional fuel pump in the combustion chamber of the

Internal combustion engine to be injected. A compressor for a gaseous fuel builds at the same drive power significantly larger and higher than a corresponding

High pressure fuel pump. Although a direct injection of the combustible gas (analogous to a direct injection of liquid fuel) in the combustion chamber of the engine is possible, but this requires a relatively high pressure level in the gas tank of at least 20 bar, whereby only an incomplete emptying of the gas tank is possible and thus the range of Motor vehicle is significantly reduced.

From DE 35 04 796 A1 an air intake for an internal combustion engine with a fuel carburetor is known, wherein the internal combustion engine can be operated optionally with a liquid fuel and a gaseous fuel. To the changing with both types of fuel requirements with regard to the inflow of

Combustion air to take into account and to reduce excess consumption during operation with gaseous fuel, a spaced apart from the carburetor disc is provided, which has a central, closable opening. This opening is released in the higher speed range of the engine, so in all

Map areas each the appropriate amount of fresh air can be sucked. From EP 0 859 176 A2 a valve for exhaust gas recirculation for an internal combustion engine with an insert is known, wherein depending on the shape of the insert

Flow rates can be varied with partially open exhaust gas recirculation valve.

Furthermore, from the prior art simple gas mixer and so-called cross mixers are known to mix the gaseous fuel of an internal combustion engine with the fresh air.

However, a disadvantage of such mixers with a fixed geometry is that, although at a stationary operating point, such as in an internal combustion engine of a

Combined heat and power plant, provide good results, but for a dynamic operation as in a motor vehicle are rather unsuitable or considerable additional control and

Require regulatory effort.

The invention is based on the object, a simple and inexpensive

To enable mixture formation of a gaseous fuel for an internal combustion engine, whereby the strict limits of the emission legislation are achieved and a dynamic engine operation without loss of function and emission disadvantages is possible.

According to the invention the object is achieved by a mixture formation device for arrangement in an intake passage of a combustion engine operated with a combustible gas, which comprises a closing member, with which the opening cross-section of the intake passage of

Internal combustion engine can be reduced, at least one metering valve for metering of the combustible gas into the intake passage of the internal combustion engine, and at least one connection for an exhaust gas recirculation of the internal combustion engine, wherein a

Fresh air flow is redirected by a Umlenkgeometrie of the closing member in a first annular channel, in particular in a diffuser, and wherein a first point of introduction for the combustible gas and a second point of introduction for the means of exhaust gas recirculation

recycled gas are arranged downstream of Umlenkgeometrie. As a result, a component can be created which represents the functions of a quantity regulator for the fresh gas stream, a gas mixer and a flow guide and flow optimization in a compact space and cost-effective manner. In addition, a comparatively good mixture preparation can be achieved with low flow resistance. Due to a Venturi effect when flowing through the mixture-forming device less fuel gas mass must be introduced into the mixture-forming device, since the pressure in the area

Suction pressure in the upstream of the mixture forming device flow section is reduced, whereby the dynamics in the field of fuel gas supply is improved. Furthermore, higher exhaust gas recirculation rates are possible due to the higher dynamics and the reduced pressure, without damaging the recirculated exhaust gas in the exhaust gas recirculation line. In this case, less Ausschiebearbeit is necessary, so that the fuel gas consumption can be reduced with such a mixture formation device.

By the features listed in the dependent claims are advantageous

Improvements and further developments of the mixture formation device specified in the independent claim possible.

In a preferred embodiment of the invention, it is provided that the at least one

Metering valve, the combustible gas metered into a fuel gas distribution ring, which is connected via a channel with the diffuser of the intake passage. Through the fuel gas distribution ring a first mixing of the combustible gas with the fresh air is possible, whereby a particularly uniform mixing of the combustible gas with the fresh air in the fuel gas distribution ring ring channel is achieved. Furthermore, the fuel gas distribution ring serves to reduce pressure peaks or to a flow equalization, whereby a homogeneous mixture formation is promoted. As a result, a particularly clean and low-emission combustion of the combustible gas is possible.

It is particularly preferred if the channel is substantially perpendicular to a

Outflow of the metering valve runs. This results in a sharp deflection of the combustible gas when hitting the wall of the vestibule, which forms vortex in the antechamber, which favor mixing of the combustible gas and the fresh air.

In a further preferred embodiment of the invention, it is provided that the

Exhaust gas recirculation has an exhaust gas recirculation distribution ring which extends at least in sections around an intake pipe of the intake duct. By connecting the exhaust gas recirculation to a second annular channel is a particularly uniform

Mixing of the recirculated exhaust gas with the mixture of fresh air and combustible gas possible, since the exhaust gas along the second annular channel can be introduced uniformly in the first annular channel via a plurality of second introduction points. Thus, the

Emission-reducing effect of exhaust gas recirculation can be optimally implemented. According to a further improvement of the invention it is provided that the closing member has a guide portion for flow guidance of the fresh air, the combustible gas and / or the recirculated exhaust gas and a guide portion, with which the closing member is guided in a housing of the mixture forming device. By a flow guide on the closing member additional control geometries for the fresh air can be omitted, which would be associated with additional components or a more complex design of the housing and would cause additional costs. In addition, a machining of the outer contour of the closing member is usually less expensive than a machining of the inner contour of the

Housing, so here a flow-optimized profile to relatively small

Manufacturing costs can be produced. By an additional guide portion on the closing member, the closing member can be guided in a simple manner in the housing without a flow impairment in the region of the guide geometry, the

Intake tube or the first annular channel is necessary.

It is preferred if the guide portion is guided on a closed housing portion of the housing. In this way, in the closed housing section in the manner of a gas spring, a negative pressure can be generated, which arises when the valve closes and thus generates a restoring force against the closing force of the valve. In order to reduce the opening and closing forces, pressure compensation bores are provided on the closing element in order to obtain overpressure or underpressure occurring during the movement of the closing element

compensate.

It is particularly preferred if a seal is arranged between the guide portion and the housing. Through a seal between the guide portion and the closed housing portion of the housing, an influx of gas into the

Compensation volume can be prevented, so that a gas exchange between the air flow of the mixture formation device and the compensating volume at least largely

is prevented.

According to a particularly advantageous development, it is provided that the closing element is hollow in the region of the guide section and encloses a compensating volume. By a hollow closure member, a comparatively large compensation volume can be limited, so that the gas forces occurring during a displacement of the closing member are comparatively small and thus easily controllable. In addition, material and mass can be saved on the closing member by a hollow closing member, whereby the dynamic behavior of the closing member can be improved. In a further preferred embodiment of the invention it is provided that the second point of introduction for the exhaust gas recirculation in the flow direction of the fresh air through the

Intake passage downstream of the first discharge point for the gas is located. Thus, the surface of the wall of the first annular channel can be optimally used and it can be formed a plurality of first and second discharge points, wherein the first discharge points preferably on a first, common bolt circle and the second discharge points are preferably on a second, common bolt circle.

In a further preferred embodiment of the invention, it is provided that the gap width of the diffuser is approximately 1/8 to 1/800 of the diameter of an intake pipe of the intake duct. The first ring channel must be flowed through both at idle and at full load. On the one hand, a minimum quantity capability and, on the other hand, a maximum power output in full load operation must be ensured. A width of 1/8 to 1/800 of the intake pipe, in particular a width or height between 50 μηη and 5 mm has indeed after application as a good compromise between the necessary throttling to

Allowing a small quantity capability and low flow loss at full load exposed.

According to an advantageous development of the invention, it is provided that the first annular channel is designed as a diffuser. By a diffuser, the outlet cross section of the first annular channel can be increased and the flow velocity (and thus the

Flow losses) can be reduced. As a result, a higher power can be achieved in particular in full load operation.

It is particularly preferred if the closing member is a valve with a valve stem and a valve disc, wherein the valve disc has a first, radially inner portion which extends at a first angle to the valve stem and has a second, radially outer portion, which under a in Compared to the first section larger angle to the valve stem runs. As a result, a diffuser can be formed between the valve and a straight wall of the housing in a simple manner.

Alternatively or additionally, it is advantageously provided that the diffuser downstream of the

Closing member is formed. As a result, a valve with a comparatively short valve plate can be used, whereby the costs and the space required for the valve can be reduced. According to an advantageous development of the mixture-forming device, provision is made for a recess to be formed on the valve disk or a wall of the diffuser opposite the valve disk and a projection protruding into the recess on the respectively opposite component. To the small quantity capability of the

It is advantageous if the valve in the

closed state as small as possible, but different from zero

Has opening cross section between the valve and the wall of the housing. This can be achieved either by very tight manufacturing tolerances, which, however, are associated with high costs, or by an additional flow obstruction, which limits the flow. Through a recess and a corresponding projection can be formed in a simple and inexpensive way a labyrinth seal, which the

Micro quantity capability of the mixture forming device improved. It is particularly advantageous if the contour of the projection has a profile. By profiling the projections, the transition from a small amount of metered combustible gas into a region with larger amounts of gas can be improved, whereby an improved

Gas acceptance is achieved and the comfort in the dynamic operation of the internal combustion engine is improved.

In a further advantageous embodiment of the invention, it is provided that the first introduction point and the second introduction point are arranged on a common diameter. Preferably, a plurality of first and a plurality of second introduction points are arranged alternately on this diameter in order to allow a uniform mixing of the fuel gas with the recirculated exhaust gas.

In a further improvement of the invention it is provided that the sum of the

Cross sections of the first discharge points for the combustible gas is less than 15%, preferably less than 10%, of the maximum cross-sectional area of the diffuser in the region of the first discharge points.

The discharge points for the recirculated exhaust gas and for the combustible gas are preferably designed as annular channels.

According to the invention is further an internal combustion engine with at least one combustion chamber, an intake passage, an exhaust passage, an exhaust gas recirculation from the exhaust passage in the

Intake channel and a mixture-forming device according to the invention proposed, wherein the metering of a combustible gas for operating the internal combustion engine through at least one controllable metering valve takes place in the mixture formation device upstream of the combustion chambers into the intake passage of the internal combustion engine.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

The invention is described below in embodiments with reference to the associated

Drawings explained. Identical components or components with the same function are identified by the same reference numerals. Show it:

Figure 1 is a schematic diagram of an internal combustion engine;

Figure 2 shows a first embodiment of an inventive

Mixture forming device in a sectional view;

FIG. 3 shows the mixture-forming device from FIG. 2 in a three-dimensional view

Presentation;

Figure 4 shows a second embodiment of an inventive

Mixture forming device in a sectional view;

FIG. 5 shows the mixture-forming device of FIG. 4 in a three-dimensional view

Presentation;

Figure 6 shows a first embodiment of a valve seat of an inventive

Forming device;

Figure 7 shows a further embodiment of a valve seat of an inventive

Forming device;

Figure 8 shows a further embodiment of a valve seat of an inventive

Forming device;

Figure 9 shows another embodiment of a valve seat of an inventive

Forming device; and FIG. 10 shows a valve seat of a mixture formation device according to the invention when the valve is partially closed.

FIG. 1 shows a greatly simplified construction of an internal combustion engine 1 with four

Combustion chambers 2, an intake passage 3 and an exhaust passage 4. Here is a

Exhaust gas recirculation 5 is provided, which connects the exhaust passage 4 with the intake passage 3 and thus allows recirculation of combusted fuel components in the intake passage 3 of the internal combustion engine 1. The internal combustion engine 1 is designed in the embodiment described below as a gas engine 1 and is operated with a gaseous fuel, preferably with natural gas (CNG - compressed natural gas). Alternatively, operation with liquefied natural gas (LNG) is also possible. Gas engines 1 differed in comparison to conventional internal combustion engines in which a liquid fuel is metered into the intake passage 3 or the combustion chambers 2, characterized in that the fuel is gaseous under ambient temperature and pressure and thus highly compressible. Thus, introduction of the gaseous fuel into the combustion chambers 2 of the internal combustion engine 1 by means of conventional injection technology, in particular by means of an injection pump and / or a fuel injection system is not or at least not efficiently possible. Natural gas can not be liquefied at room temperature, causing the

The use of fuel injection technology for liquid fuels is also eliminated. Therefore, for gas engines 1, alternative mixture-forming devices have been developed which are specially adapted to the particularities of a gaseous fuel. The mixture formation is preferably carried out in the intake passage 3 upstream of the combustion chambers 2 of the internal combustion engine 1, since at this point the pressure level is lower than in the combustion chambers 2 and the gas tanks can thus be further emptied.

FIG. 2 shows a first exemplary embodiment of a mixture formation device 10 according to the invention for an internal combustion engine 1 operated with a gaseous fuel. The mixture formation device 10 comprises a housing 42, in which a closure member 12, in particular a valve 54, is displaceably arranged. The housing 42 has a first, in the plane of the drawing vertically extending portion in which a

Intake manifold 36 is formed. The housing 42 further includes a second portion which forms a diffuser 22. The diffuser 22 extends at an angle of about 100 ° to 120 ° to the intake manifold 36. On the housing 42, a closed housing portion 44 is further formed, which defines a compensating volume 48 together with the closing member 12. The closing member 12 is designed as a valve 54, in particular as a poppet valve, formed, and has a valve stem 56 and a valve plate 58. The valve stem 56 and the valve plate 58 form on their side facing the intake pipe 36 a

Conduction portion 38 through which fresh air flowing through the mixture forming device is guided and deflected. Between the valve stem 56 and the valve plate 58, a Umlenkgeometrie is formed, which by the intake manifold 36 in the

Mixing device 10 inflowing incoming fresh air into the diffuser 22. The valve disk 58 is followed by a guide section 40, in which the valve 54 is guided in the closed housing section 44. The closing member 12 is in the range of

Guide portion 40 is hollow and surrounds the compensating volume 48. Between the guide portion 40 and the housing wall of the closed housing portion 44, a seal 46 is arranged, which the penetration of fresh air into the

To prevent equalization volume 48.

The mixture forming device 10 further comprises at least one, preferably as shown in Figure 1 a plurality, preferably evenly distributed over the circumference of the mixture forming device 10, receiving opening (s) 78, in each of which a metering valve 16 for supplying a combustible gas is arranged. The metering valve 16 has at its periphery a seal 76, in particular a sealing ring, with which a gap between the

Metering valve 16 and the receiving opening 78 is sealed and thus an uncontrolled leakage of the combustible gas is prevented from the mixture formation device 10. Each of the receiving openings 78 is in each case connected to a fuel gas distribution ring 28, in which 16 can be mixed via the metering valves 16 supplied gaseous fuel with fresh air. The fuel gas distribution ring 28 is connected to the diffuser 22 via channels 30

connected, wherein the channels 30 each extend substantially perpendicular to the diffuser 22. In order to allow a combustible gas to be introduced into the diffuser 22, first inlet points 24 are respectively formed at an end of the channel 30 facing the diffuser 22, via which channels 30 are fluidically connected to the diffuser 22. Here, the channels 30 extend substantially perpendicular to the outflow openings 32 of the metering valves 16. The metering valves 16 are arranged radially, that is, aligned perpendicular to the intake pipe 36 of the mixture formation device 10. The metering valves 16 each have a plug 52 with which the metering valves 16 can be electrically contacted.

At the mixture formation device 10, a connection for an exhaust gas recirculation 5 of the internal combustion engine 1 is formed. In this case, the mixture formation device 10 has an exhaust gas recirculation distribution ring 34, which is at least partially guided around the intake pipe 36 of the intake duct 3 around. The second annular channel 34 extends substantially parallel to the diffuser 22 and is connected via second inlet 26 with this diffuser 22. In this case, the exhaust gas recirculation distribution ring 34 is connected via at least one port 18 to the exhaust gas recirculation 5.

FIG. 3 shows the mixture-forming device 10 in a three-dimensional representation. It can be seen that the metering valves 16 perpendicular to the intake pipe 36th

are aligned and not in the radial direction over the housing 42 of the

Prevent mixture formation device 10.

During operation of the mixture formation device 10, fresh air is sucked into the mixture formation device 10 via the intake pipe 36. At the same time, the combustible gas is metered by means of the metering valves 16 into the fuel gas distribution ring 28, where a first mixing of the combustible gas with the fresh air takes place. By the deflection of the gas from the

Outflow opening 32 of the metering valve 16 via the wall of the vestibule and the

Forwarding through the channel 30 into the diffuser 22, a turbulence, which causes a uniform mixing of fresh air and combustible gas. Downstream of the first introduction point 24, the mixture of fresh air and combustible gas is additionally supplied with exhaust gas recirculated via the exhaust gas recirculation 5 and the exhaust gas recirculation distribution ring 34. For this purpose, the recirculated exhaust gas is introduced into the diffuser 22 at a second introduction point 26, wherein the exhaust gas is mixed with the mixture of fresh air and combustible gas.

The closing member 12 has the function of a quantity controller and can thus replace the throttle in a conventional internal combustion engine. The mixture-forming device 10 in FIG. 2 is shown with the valve 54 fully open, that is to say maximally de-throttled. By closing the valve 54, that is, a displacement in the direction of a seat edge 74 on the housing 42, an opening cross-section 14 of the diffuser 22 can be reduced. Such a partially closed valve 54 is shown in FIG. In this case, the valve disk 58 in the region of the guide portion 40 a in the flow direction of the gas through the diffuser 22 sharp trailing edge, which provides in the diffuser 22 downstream of the valve disk 58 for vortex formation, wherein a wake 80 additional mixing of fresh air, combustible gas and exhaust gas from the exhaust gas recirculation 5 causes. In this case, on the one hand, a minimum quantity capability, in particular during idling of the internal combustion engine 1, as well as a streamlined and preferably low-loss flow guidance in full load operation must be made possible. The adjustment of the valve 54 takes place for example via a Electromechanical control, but may alternatively be purely mechanical, for example via a spindle, a rocker arm, a toothing or the like.

In Figure 4 is an alternative embodiment of an inventive

Mixture forming device 10 shown. With essentially the same structure as explained with reference to FIG. 2, only the remaining differences will be discussed below. The metering valves 16 are in this embodiment, axial, that is parallel to the

Intake pipe 36, arranged. As a result, additional space is created in the radial direction, so that the available space can be used optimally. According to the axial arrangement of the metering valves 16, the shape of the fuel gas distribution ring 28 is adapted accordingly, wherein the channel 30 at one of the intake pipe 36 facing the end of

Brenngasverteilrings 28 is formed and is arranged eccentrically from the discharge opening 32 of the metering valve 16, a correspondingly multiple deflection and

Mixing of the combustible gas with the fresh air in the fuel gas distribution ring 28 to achieve. FIG. 5 shows this exemplary embodiment of a mixture formation device 10 in a three-dimensional representation.

In Figure 6, an alternative embodiment of the valve 54 and the diffuser 22 is shown. In this case, the valve 54 at its valve plate 58 has a first, radially inner

Section 60 and a second, radially outer portion 62, which extends at a larger angle compared to the first portion 60 to the valve stem 56. This results between a wall 64 of the housing 42 and the second portion 62 of the

Valve plate 58, a diffuser 50. Alternatively, the diffuser 50 may also, as shown in Figure 7 between two housing parts or housing portions of the housing 42 downstream of the valve plate 58 may be formed.

In order to improve the small quantity capability of the mixture forming device 10, a simple labyrinth seal may be provided on the valve seat of the valve 54. For this purpose, as shown in FIG. 8, a recess 66 can be provided on the wall 64 of the housing 42, into which, when the valve 54 is substantially closed, a projection 70 on the valve disk 58 engages. Alternatively, as shown in Figure 9, a projection 72 may be formed on the wall 64 of the housing 42, which engages in a recess 68 in the valve plate 58. By profiling the projections 70, 72, the transition from a small amount of metered combustible gas into a region with larger amounts of gas can be improved, whereby the comfort in the dynamic operation of the internal combustion engine 1 is improved. LIST OF REFERENCE NUMBERS

Internal combustion engine / gas engine

combustion chamber

intake port

exhaust duct

Exhaust gas recirculation

Forming device

closing member

Opening cross-section

metering

Connection pressure compensation hole

diffuser

first discharge point

second discharge point

Fuel gas distribution channel

outflow

Exhaust gas recirculation distribution ring

intake

Guide section guide section

casing

closed housing section

poetry

compensating volume

diffuser plug

Valve

Valve stem valve disk first section second section wall

Recess recess projection projection seat edge seal

receiving opening

Wirbelschleppe

Claims

claims

A mixture forming device (10) for arrangement in an intake passage (3) of a combustion engine (1) driven by a combustible gas

a closing member (12) with which the opening cross section (14) of the intake duct (3) of the internal combustion engine (1) can be reduced,

at least one metering valve (16) for metering the combustible gas into the

Intake duct (3) of the internal combustion engine (1), as well

at least one connection (18) for an exhaust gas recirculation (5) of the

Internal combustion engine (1), characterized in that

a fresh air flow through a Umlenkgeometrie of the closing member (12) in a

Diffuser (22) is diverted, with

a first point of introduction (24) for the combustible gas and a second point of introduction (26) for the gas recirculated by means of the exhaust gas recirculation (5) downstream of the Umlenkgeometrie are arranged.

Mixturing device (10) according to claim 1, characterized in that the at least one metering valve (16) metered the combustible gas into a fuel gas distribution ring (28) which is connected via a channel (30) with the diffuser (22) of the intake duct (3) ,

Mixturing device (10) according to claim 2, characterized in that the channel (30) extends substantially perpendicular to an outflow opening (32) of the metering valve (16).

The mixture forming device (10) according to any one of claims 1 to 3, characterized in that the exhaust gas recirculation (5) has an exhaust gas recirculation distribution ring (34) which at least partially around an intake pipe (36) of the

Intake duct (3) is guided around.

Mixture-forming device (10) according to one of claims 1 to 4, characterized in that the closing member (12) has a guide portion (38) for

Flow guidance of the fresh air, the combustible gas and / or the recirculated Exhaust gas and a guide portion (40), with which the closing member (12) in a housing (42) of the mixture-forming device (10) is guided.

6. mixture forming device (10) according to claim 5, characterized in that the guide portion (40) on a closed housing portion (44) of the housing (42) is guided.

7. mixture forming device (10) according to claim 5 or 6, characterized in that between the guide portion (40) and the housing (42) has a seal (46) is arranged.

8. mixture forming device (10) according to any one of claims 5 to 7, characterized

characterized in that the closing member (12) in the region of the guide portion (40) is hollow and encloses a compensation volume (48).

9. mixture forming device (10) according to any one of claims 1 to 8, characterized

in that the second introduction point (26) for the exhaust gas recirculation in

Flow direction of the fresh air through the intake passage (3) downstream of the first

Einleitstelle (24) for the gas is.

10. mixture forming device (10) according to any one of claims 1 to 9, characterized

in that the gap width of the diffuser (22) is about 1/8 to 1/800 of the

Diameter of an intake pipe (36) of the intake passage (3).

1 1. mixture forming device (10) according to one of claims 1 to 10, characterized

characterized in that the closure member (12) is a valve (54) having a valve stem (56) and a valve disk (58), the valve disk (58) having a first radially inner portion (60) which is at a first angle to Valve stem (56) extends and a second, radially outer portion (62) which under a larger compared to the first portion (60) at an angle to the valve stem (56) extends.

12. mixture forming device (10) according to claim 1 1, characterized in that the diffuser (22) downstream of the closing member (12) is formed.

13. mixture forming device (10) according to any one of claims 1 to 12, characterized

in that on the valve disk (58) or one of the valve disk (58) opposite wall (64) of the diffuser (22) has a recess (66, 68) and on the respectively opposite component (58, 64) in the recess (66, 68) protruding projection (70, 72) is formed.

14. mixture forming device (10) according to any one of claims 1 to 8 or 10 to 13, characterized in that the first introduction point (24) and the second discharge point (26) are arranged on a common diameter.

15. Gas engine (1) with at least one combustion chamber (2), an intake passage (3), a

Exhaust gas channel (4), an exhaust gas recirculation (5) and a mixture formation device (10) according to one of claims 1 to 14, wherein the metering of a combustible gas for operating the gas engine (1) by a controllable metering valve (16) upstream of the combustion chamber (2) in the intake passage (3) of the gas engine (1).