EP4724686A1

EP4724686A1 - Gas valve for an internal combustion engine

Info

Publication number: EP4724686A1
Application number: EP23751248.8A
Authority: EP
Inventors: Sandro Rivellini
Original assignee: Innio Jenbacher GmbH and Co OG
Current assignee: Innio Jenbacher GmbH and Co OG
Priority date: 2023-08-01
Filing date: 2023-08-01
Publication date: 2026-04-15
Also published as: WO2025024871A1

Abstract

Gas valve for an internal combustion engine, comprising: a valve seat ( 32), and a valve body (30) movable along a longitudinal axis (33) of the valve body (30), wherein in a closed state of the gas valve (26) the valve body (30) contacts the valve seat (32) at a contact surface, wherein adjacent to the valve seat (32) there is provided a cylindrical portion (34) with a first, preferably circular, cross-section, the valve body (30) comprises a second, preferably circular, cross-section generally corresponding to the first cross- section, and the valve body (30) is at least partially arranged in the cylindrical portion (34) when the gas valve (26) is in the closed state.

Description

Gas valve for an internal combustion engine

The present invention relates to a gas valve for an internal combustion engine according to the preamble of claim 1 and an internal combustion engine comprising such a gas valve .

Hereinafter, the state of the art will be explained with reference to an example embodiment of an internal combustion engine comprising a pre-chamber . Generally, this explanation analogously applies to any gas valves used for internal combustion engines .

Pre-chambers are used as ignition ampli fiers for internal combustion engines , preferably starting from a certain si ze of internal gas engines ( generally with cylinder capacity above about four liters ) , in order to properly ignite a lean air- fuelmixture in the large volume of the cylinders .

Such pre-chambers in most cases are supplied with air, fuel or an air- fuel-mixture separately from the main combustion chamber .

Therefore , it is known in the state of the art that pre-chamber assemblies for internal combustion engines comprise :

- a valve seat , and

- a valve body movable along a longitudinal axis of the valve body, wherein in a closed state of the gas valve the valve body contacts the valve seat at a contact surface .

During li fetime of the pre-chamber gas valve wear occurs between the valve body and the valve seat ef fected by the repeated contact movement between these two components .

Furthermore , the valve body is pressed against the valve seat during combustion of the internal combustion engine by the acting forces and pressures inside the combustion chamber and the precombustion chamber, wherein the wear is increased .

The wear between the valve seat and the valve body does af fect the closing characteristic of the gas valve , wherein the closing times is variated .

The variation of the closing times does mainly af fect the operation characteristics of the internal combustion engine , wherein the pre-chamber gas valve or the parts ef fected by wear have to be changed after a certain number of operating hours , to guarantee the smooth operation of the internal combustion engine .

Furthermore , the wear does also af fect the tightness of the prechamber gas valve .

The same af fects occur during operation and li fetime of valves used as intake or exhaust valves for main combustion chambers of internal combustion engines .

The obj ect of the present invention is therefore to provide a gas valve for an internal combustion engine as well as an internal combustion engine having such a gas valve which at least partly improves upon the mentioned negative ef fects compared to the prior art and/or to provide a more reliable gas valve system and/or to provide a more consistent actuation of the gas valve over its li fetime .

This obj ect is achieved with a gas valve for an internal combustion engine with the features of claim 1 as well as an internal combustion engine having such a gas valve .

According to the invention, a gas valve , preferably a pre-chamber gas valve , for an internal combustion engine comprises : - a valve seat , and

- a valve body movable along a longitudinal axis of the valve body, wherein in a closed state of the gas valve the valve body contacts the valve seat at a contact surface , wherein

- adj acent to the valve seat there is provided a cylindrical portion with a first , preferably circular, cross-section,

- the valve body comprises a second, preferably circular, crosssection generally corresponding to the first cross-section, and

- the valve body is at least partially arranged in the cylindrical portion when the gas valve is in the closed state .

By use of a geometry having a cylindrical portion with a first , preferably circular, cross-section adj acent to the valve seat , wherein the valve body is at least partially arranged in the cylindrical portion when the gas valve is in the closed state and comprises a, preferably circular, second cross-section generally corresponding to the first cross-section, during an opening stroke the valve body moves clear of the cylindrical portion, such that a fluid connection is established .

In this way, the fluid connection is established independently from a contact surface between the valve seat and the valve body, wherein also an acting wear at the contact surface does not af fect the valve opening and/or closing characteristic .

Therefore , a fluidical connection is provided to supply air, fuel or an air- fuel mixture to a target volume , in particular a combustion chamber or a pre-chamber, via a gap between the cylindrical portion and the valve body during an opening stroke , when the valve body moves clear of the cylindrical portion .

The first and/or the second and/or third cross section can be seen substantially perpendicularly to the longitudinal axis . That the second cross-section generally corresponds to the first cross-section can in the context of the invention be understood such that there is a sealing ef fect between the valve body and the cylindrical portion while the valve body remains movable relative to the cylindrical portion .

In context of the present invention, the wording that one part is adj acent to another part does not necessarily mean to be directly adj acent , which is however preferred .

"Adj acent" can be understood to mean adj acent in the direction of the longitudinal axis . It can also be provided that between the two parts e . g . , a rounding or a recess is provided .

The cylindrical portion is in preferred embodiments a single contiguous portion . However, embodiments are conceivable where the cylindrical portion has gaps or interruptions or the like so that in essence one or more further cylindrical portions are present .

The longitudinal axis can particularly preferably be straight . Slight curvatures in principle are conceivable .

By use of a gas valve according to the invention, furthermore the opening characteristic of the valve can be decoupled from the movement of the valve body relatively to the vale seat . Therefore , an opening - a supplying of air, fuel or an air- fuel mixture to a target volume - is done when the valve body moves clear of the cylindrical portion, otherwise they are disconnected and a supply is interrupted .

In a speci fic embodiment of the invention, the valve body is guided longitudinally in the cylindrical portion . During the movement of the valve body, and the fluid connection is established, when the valve body moves clear of the cylindrical portion . In contrast , the state of the art defines valve needles , wherein upon a start of movement of the valve needle (when the valve is li fted from a valve seat ) the supply ( i . e . , the fluid communication) starts .

In this way, it is possible by adj ustment of the cylindrical portion ( geometry and length) to adj ust a supply characteristic of the gas valve , for example by modulating an already existing movement instead of directly adj usting the actuator movement regarding a desired or required supply characteristic .

Furthermore , by taking advantage of a system according to the invention, already present motions of other components of the internal combustion engine may be trans ferred to actuate the gas valve , such that in an efficient and/or energy saving way a reliable actuation system of the pre-chamber gas valve can be provided .

Already present internal combustion engines can be upgraded with at least one gas valve according to the invention .

All measures and features described in connection with the prior art can also be taken in connection with the invention .

The invention can preferably be used in conj unction with a reciprocating piston engine , in particular driving a generator for creating electrical energy . Combinations of internal combustion engines driving a generator are known as gensets .

Advantageous embodiments are defined in the dependent claims .

It can be provided that the valve seat is attached to or provided by the valve housing . It can be provided that the cylindrical portion essentially comprises the same diameter as the valve body . In this context , essentially the same diameter has to be understood in such a way that the cylindrical portion and the valve body comprise the same manufacturing measurements , wherein the necessary di f ferences in the measurements can be provided by manufacturing tolerances ( e . g . a H7 /g6 clearance fit ) .

It can be provided that between the cylindrical portion and the valve body a clearance fit is present .

There can be provided, preferably in a valve housing, at least one gas channel configured to provide air, fuel or an air- fuel mixture to be supplied to a target volume via the gap between the cylindrical portion and the valve body .

It can be provided that the cylindrical portion is provided with such a length that the valve body clears the cylindrical portion in a pos ition o f the valve body relative to the valve seat 20% to 100% , preferably 25% to 100% , particularly preferably 25% to 75% , of the longitudinal stroke of the valve body .

In this content , the longitudinal stroke of the valve body can be provided by the longitudinal range in which the valve body i s moved during application, e . g . , beginning from a position of the valve body, wherein the valve body is in contact with the valve seat , until a position of the valve body, wherein the valve body is maximally li fted up from the valve seat .

Such positions can be seen as a non-actuated position ( the valve body is in contact with the valve seat ) and a maximum actuated position ( the valve body is maximally li fted up from the valve seat ) . These positions - or at least one of them - can also be seen as end stroke positions . It can be provided that the valve body is pre-loaded by an energy storage , preferably a coil spring, against the valve seat .

It can be provided that adj acent to the cylindrical portion there is a flow passage portion with a third cross-section which is larger in area than the second cross-section .

It can be provided that the third cross-section comprises azimuthally distributed azimuthal guiding regions which generally correspond to the f irst cross-section and/or the second cross-section in the respective azimuthal guiding region .

It can be provided that the third cross-section is expanded, preferably in the shape of an arc, particularly preferably circular arc, between the azimuthal guiding regions .

It can be provided that the guidance of the valve body i s ef fected by a valve housing, preferably at azimuthal guiding regions .

It can be provided that the valve body comprises at least one guiding surface extending along the longitudinal axis .

It can be provided that the cylindrical portion is provided by a bore .

It can be provided that a mechanical actuation system is provided for actuating the gas valve by imparting a motion on the gas valve , preferably the valve body, for opening and/or closing the at least one gas valve .

It can be provided that the mechanical actuation system is provided purely mechanically, wherein e . g . no electrical or hydraulic actuation (with a possible exception of hydraulic valve lash compensation) is done . It can be provided that the gas valve according to the invention is implemented as pre-chamber gas valve .

It can be provided that the mechanical actuation system comprises at least one pre-chamber gas valve rod .

It can be provided that a linear motion i s imparted on the gas valve body for opening and/or closing the at least one gas valve by the pre-chamber gas valve rod of the mechanical actuation system .

The pre-chamber gas valve rod is provided e . g . to transfer actuation motions (preferably already present ) from an actuator to the gas valve body, wherein by the pre-chamber gas valve rod a linear motion is imparted on the gas valve body .

It can be provided that the at least one pre-chamber gas valve rod is pivotably connected at a first end to the gas valve body and/or at a second end to an actuation system .

Therefore , it can be provided that the pre-chamber gas valve rod is used to trans fer a motion of the actuation system into a linear motion which is used to be imparted by the pre-chamber gas valve rod on the gas valve body .

It can be provided that the pre-chamber gas valve rod comprises along its longitudinal extension at least two separate prechamber gas valve rod components , which are adj ustably connected relative to each other, preferably by a screw connection, wherein a longitudinal extension of the pre-chamber gas valve rod can be adj usted .

By adj usting the longitudinal extension of the pre-chamber gas valve rod, e . g . , the opening and/or closing characteristic o f the gas valve can be adj usted, wherein the timing of opening and/or closing, the opening time ( i . e . , the time period during which the gas valve is open) , the closing time ( i . e . , the time period during which the gas valve is closed) and/or the opening stroke of the gas valve body can be adj usted, wherein the supplied volume of air, fuel , or the air- fuel mixture as well as the timing of the supplying via the gas valve are adj ustable .

It can be provided that the pre-chamber gas valve rod comprises at least two pre-chamber gas valve rod components which are rotatably connected to each other, wherein the pre-chamber gas valve rod component contacting the gas valve body i s pivotable relative to another one of the at least two pre-chamber gas valve rod components via a first pivot .

It can be provided that at least one of the at least two prechamber gas valve rod components comprises an L-shape . By use of an L-shape , e . g . , areas directly can be freed for additional components of the internal combustion engine .

It can be provided that the pre-chamber gas valve rod is provided by the at least two pre-chamber gas valve rod components which are rotatably connected to each other ( e . g . , wherein a crank mechanism and/or mechanical linkage is formed) .

It can be provided that the pre-chamber gas valve rod component contacting the gas valve body comprises at the contact surface between the pre-chamber gas valve rod component and the gas valve body along its contact surface a variable distance from the first pivot .

By use of a variable distance from the first pivot , the prechamber gas valve rod component can trans fer a linear motion to the gas valve body when the pre-chamber gas valve rod component is rotated around the first pivot ( similar to a cam o f a cam shaft ) .

Particularly preferably, by choosing an accurate variation of the distance of the contact surface from the first pivot , the supplied volume and the timing of the supplying via the gas valve are adj ustable .

It can be provided that between the pre-chamber gas valve rod and the gas valve body at least one , preferably spherical and/or cylindrical (preferably with circular base area ) , decoupling component is arranged, transmitting an actuation motion from the pre-chamber gas valve rod to the gas valve body .

By use of such a decoupling element between the pre-chamber gas valve rod and the gas valve body, it can be provided that only linear motions acting along a longitudinal extension of the gas valve body are transmitted to the gas valve body . The gas valve body can therefore be prevented from other motions , e . g . , oblique to the longitudinal extension of the gas valve body, of the prechamber gas valve rod (motions which might damage or af fect the operation of the gas valve ) .

It can be provided that the mechanical actuation system is connected to and/or comprises a rocker arm .

It can be provided that the rocker arm is pivoted on a second pivot and configured to actuate at least one inlet valve and/or outlet valve of the internal combustion engine for opening and closing the at least one inlet valve and/or outlet valve , particularly preferred wherein a push rod is connected to the rocker arm for actuating the rocker arm and therefore the at least one inlet valve and/or outlet valve . It can be provided that the mechanical actuation system is configured to transmit a rotational motion of a cam shaft o f the internal combustion engine to the gas valve body, preferably wherein the gas valve is provided as pre-chamber gas valve .

In particularly preferred embodiments , the rotational motion of the cam shaft is trans ferred to a motion of the rocker arm through a push rod which is pivotably connected to the rocker arm . In such embodiments , preferably the rocker arm is configured to actuate the at least one inlet valve and/or the at least one outlet valve .

It can be provided that the gas valve body i s configured to be moved linearly along its longitudinal axis relative to the gas valve seat to perform an opening and/or closing of the gas valve .

It can be provided that the gas valve comprises at least one spring, wherein the spring is configured to perform a closing motion of the gas valve and/or to keep the gas valve closed, preferably i f no linear motion is imparted by the mechanical actuation system .

It can be provided that the at least one spring biases the gas valve body onto the valve seat .

In preferred embodiments , the gas valve body is long enough to extend from the gas valve and/or the valve seat thereof to an exterior of a component part making up a part of the pre-chamber, preferably a top part of the pre-chamber .

Also , protection is sought for an internal combustion engine comprising at least one gas valve according to the invention .

At least one main combustion chamber and a pre-chamber fluidically connected to the at least one main combustion chamber can be provided, wherein for supplying air, fuel or an air-fuel mixture to the pre-chamber and/or the main combustion chamber the least one gas valve is provided.

A mechanical actuation system can be provided for actuating the gas valve by imparting a motion on the gas valve, preferably the valve body, for opening and/or closing the at least one gas valve .

It can be provided that by use of the mechanical actuation system a motion of a cam shaft of the internal combustion engine is transformed into an actuation motion of the gas valve.

Further details and advantages of the invention are apparent from the accompanying figures and the following description of the drawings. The figures show:

Fig. 1 a first embodiment of a gas valve according to the invention

Fig. 2 an embodiment of a pre-chamber assembly,

Fig. 3 the embodiment of Fig. 2 in a closed position of the pre-chamber gas valve,

Fig. 4 the embodiment of Fig. 2 in an open position of the pre-chamber gas valve,

Fig. 5 a second embodiment of a pre-chamber assembly,

Fig. 6 the second embodiment of Fig. 5 in a closed position of the pre-chamber gas valve,

Fig. 7 the second embodiment of Fig. 2 in an open position of the pre-chamber gas valve,

Fig. 8 a third embodiment of a pre-chamber assembly,

Fig. 9 the third embodiment of Fig. 8 in a closed position of the pre-chamber gas valve, and

Fig. 10 the third embodiment of Fig. 8 in an open position of the pre-chamber gas valve. As motions ( already present for di f ferent purposes ) od the internal combustion engine do not always or ideally correspond to desired motions for actuating a gas valve 26 ( e . g . , a prechamber gas valve 2 ) , it is desirable to provide a possibility to reconcile these already available motions with desired motions or characteristics for actuating a gas valve 26 .

This would be possible by use of cost and place consuming transmissions or - as shown in the following Figures - by use o f an embodiment of a gas valve 26 according to the invention .

Fig . 1 discloses a first embodiment of a gas valve 26 according to the invention .

As can be seen by Fig . 1 , the gas valve 26 is actuated by a mechanical actuation system 6 .

The mechanical actuation system 6 transmits a motion of the cam shaft 28 - exactly speaking a l inear motion of the roller tappet 37 guided at the cam 29 o f the cam shaft - via the push rod 27 to a rocker arm 24 , wherein the rocker arm 24 is pivotally connected around the second pivot 18 to redirect the motion of the push rod 27 to the pre-chamber gas valve rod 7 .

By the motion of the pre-chamber gas valve rod 7 caused by the rocker arm 24 , the pre-chamber gas valve rod 7 imparts a linear motion on the valve body 30 via the contact surface 14 of the pre-chamber gas valve rod 7 .

The gas valve 26 comprises a valve seat 32 , and a valve body 30 movable along a longitudinal axis 33 of the valve body 30 , wherein in a closed state of the gas valve 26 the valve body 30 contacts the valve seat 32 at a contact surface . Adj acent to the valve seat 32 there is provided a cylindrical portion 34 with a first circular cross-section .

The valve body 30 comprises a circular second cross-section generally corresponding to the first cross-section of the cylindrical portion 34 .

The valve body 30 is arranged in the cylindrical portion 34 when the gas valve 26 is in the closed state .

By use of a geometry having a cylindrical portion with a first circular cross-section adj ected to the valve seat 32 , wherein the valve body 30 is at least partially arranged in the cylindrical portion 34 when the gas valve 26 i s in the closed state and comprises a preferably circular second cross-section generally corresponding to the first cross-section, during an opening stroke the valve body 30 ( shown by the dashed line ) moves clear of the cylindrical portion 34 , such that a fluid connection is established .

A fluid connection is established independently from a contact surface between the valve seat 32 and the valve body 30 , wherein also an acting wear at the contact surface does not af fect the valve opening and/or closing characteristic .

Adj acent to the cylindrical portion 34 there is a flow passage portion 35 with a third cross-section which is larger in area than the second cross-section .

The flow passage portion 35 comprises azimuthally distributed azimuthal guiding regions 36 which generally correspond to the first cross-section and/or the second cross-section in the respective azimuth guiding region 36 . The third cross-section is expanded in the shape of circular arcs 37 between the azimuthal guiding regions 36 .

The guidance of the valve body 30 is ef fected by a valve housing 31 and the azimuthal guiding regions 36 .

The cylindrical portion 34 is provided by a bore .

Fig . 2 discloses a embodiment of a pre-chamber assembly 1 of an internal combustion engine .

The embodiment of a pre-chamber assembly 1 of Fig . 2 i s shown in Fig . 3 in a closed pos ition of the pre-chamber gas valve 2 and in Fig . 4 in an open position of the pre-chamber gas valve 2 .

The first embodiment of the assembly 1 of Fig . 2 to 4 comprises a rocker arm 24 pivotally connected to the second pivot 18 .

The rocker arm 24 is configured to actuate at least one inlet valve 19 and/or outlet valve 20 for opening and closing the at least one inlet valve 19 and/or outlet valve 20 .

The at least one inlet valve 19 and/or outlet valve 20 is therefore connected to the rocker arm 24 , wherein the pivoting motions o f the rocker arm 24 are trans formed in a known way to a linear operation for opening and closing the at least one inlet valve 19 and/or outlet valve 20 along its longitudinal axis .

The rocker arm 24 ( as is known from the state of the art ) is actuated by a push rod 27 (not shown for reasons of clarity) which can be connected to the rocker arm 24 at the connecting point 23 , wherein the rocker arm 24 is pivotable and therefore the at least one inlet valve 19 and/or outlet valve 20 is linearly actuated . The push rod 27 can be actuated by a cam shaft 28 of the internal combustion engine , wherein by the eccentric geometry of the cam shaft 28 the linear motion and actuation motion for the rocker arm 24 can by created .

Furthermore , the pre-chamber assembly 1 comprises a pre-chamber gas valve 2 for supplying air, fuel or an air- fuel-mixture to the pre-chamber 3 .

The pre-chamber gas valve 2 comprises a pre-chamber gas valve seat 4 and a pre-chamber gas valve body 5 , wherein by a linear motion of the pre-chamber gas valve body 5 the pre-chamber gas valve body 5 can be moved relative to ( li fted from) the prechamber gas valve seat 4 to perform for opening and/or closing the at least one pre-chamber gas valve 2 .

In other words : The pre-chamber gas valve body 5 is configured to be moved linearly along its longitudinal axis relative to the pre-chamber gas valve seat 4 to perform an opening and/or closing of the pre-chamber gas valve 2 .

For actuating the pre-chamber gas valve 2 , a mechanical actuation system 6 is provided .

The mechanical actuating system 6 of the first embodiment disclosed by Fig . 2 to 4 is provided by a pre-chamber gas valve rod 7 .

The pre-chamber gas valve rod 7 is pivotably connected at a first end to the pre-chamber gas valve body 5 and/or at a second end in the connecting point 23 to the actuation system 8 ( the rocker arm 24 ) .

Furthermore , the pre-chamber gas valve rod 7 shown by Fig . 2 to 4 is linearly guided by the linear guiding device 21 ( as can be seen in more detail by the two di f ferent positions o f the pre-chamber gas valve rod 7 of Fig . 3 and 4 ) .

By the motion of the pre-chamber gas valve rod 7 caused by the rocker arm 24 , the pre-chamber gas valve rod 7 imparts a linear motion on the pre-chamber gas valve body 5 via the contact surface 14 of the pre-chamber gas valve rod 7 .

Between the pre-chamber gas valve rod 7 and the pre-chamber gas valve body 5 , a spherical decoupling component 16 is provided, transmitting the linear motion from the pre-chamber gas valve rod 7 to the pre-chamber gas valve body 5 .

By use of such a decoupling element 16 between the pre-chamber gas valve rod 7 and the pre-chamber gas valve body 5 , essentially only linear motions acting along a longitudinal extension of the pre-chamber gas valve body 5 can be transmitted to the prechamber gas valve body 5 .

The pre-chamber gas valve body 5 can therefore be prevented from other motions , e . g . , oblique to the longitudinal extension o f the pre-chamber gas valve body 5 , done by the pre-chamber gas valve rod 7 (motions which might damage or af fect the operation of the pre-chamber gas valve 2 ) .

Speci fically in this embodiment , the linear motion imparted on the pre-chamber gas valve body 5 i s used to implement an opening of the pre-chamber gas valve 2 .

For closing the pre-chamber gas valve 2 , a spring (not shown for reasons of clarity of the depiction) is provided, wherein the spring is configured to perform a closing motion of the prechamber gas valve 2 and/or to keep the pre-chamber gas valve 2 closed . The pre-chamber gas valve rod 7 of Fig. 2 to 4 comprises along its longitudinal extension three separate pre-chamber gas valve rod components 9, 10, 11, which are adjustably connected relative to each other (in this embodiment by a screw connection) , wherein a longitudinal extension of the pre-chamber gas valve rod 7 can be adjusted.

In this embodiment, an axis of the screw connection and a longitudinal axis of the pre-chamber gas valve rod 7 essentially coincide .

To lock the connection of the three separate pre-chamber gas valve rod components 9, 10, 11, furthermore, two counter nuts 25 are provided in this embodiment.

Also, embodiments using only one counter nut 25 are quite possible .

By adjusting the longitudinal extension of the pre-chamber gas valve rod 7, the opening and/or closing characteristic of the pre-chamber gas valve 2 can be adjusted.

Fig. 5 discloses a second embodiment of a pre-chamber assembly 1.

The second embodiment of a pre-chamber assembly 1 of Fig 5 is shown in Fig. 6 in a closing position of the pre-chamber gas valve 2 and in Fig. 7 in an opening position of the pre-chamber gas valve 2.

Compared to the first embodiment, the second embodiment of Fig. 5 to 7 comprises a pre-chamber gas valve rod 7 provided by two pre-chamber gas valve rod components 12, 13 which are rotatably connected to each other, wherein the pre-chamber gas valve rod component 13 contacting the pre-chamber gas valve body 5 i s pivotally connected to a first pivot 15 .

The pre-chamber gas valve rod component 13 contacting the prechamber gas valve body 5 comprises at the contact surface 14 between the pre-chamber gas valve rod component 13 and the prechamber gas valve body 5 along its contact surface a variable distance from the first pivot 15 .

By use of a variable distance of the contact surface 14 from the first pivot 15 , the pre-chamber gas valve rod component 13 can trans fer a linear motion to the pre-chamber gas valve body 13 when the pre-chamber gas valve rod component 13 is rotated around the first pivot 15 .

By choosing an accurate variation of the distance of the contact surface 14 from the first pivot 15 , the supplied volume and the timing of the supplying via the pre-chamber gas valve 2 are adj ustable ( in other words : the opening and/or closing characteristic of the pre-chamber gas valve 2 can be adj usted) .

The remaining characteristics of the second embodiment shown by Fig . 5 to 7 essentially comply with the first embodiment shown by Fig . 2 to 4 .

Fig . 8 discloses a third embodiment of a pre-chamber assembly 1 .

The third embodiment of a pre-chamber assembly 1 of Fig 8 i s shown in Fig . 9 in a closed position of the pre-chamber gas valve 2 and in Fig . 10 in an open position of the pre-chamber gas valve 2 .

As well as the second embodiment , also the third embodiment of Fig . 8 to 10 comprises a pre-chamber gas valve rod 7 provided by two pre-chamber gas valve rod components 12 , 13 which are rotatably connected to each other, wherein the pre-chamber gas valve rod component 13 contacting the pre-chamber gas valve body 5 is pivotally connected to a first pivot 15 .

Compared to the second embodiment , the third embodiment disclosed by Fig . 8 to 10 comprises a pre-chamber gas valve rod component 13 designed with an L-shape , whereby the area directly above the pre-chamber gas valve 2 can be freed for additional components of the internal combustion engine .

The pre-chamber gas valve rod component 13 is pivotably arranged at the first pivot 15 .

The pre-chamber gas valve rod component 13 furthermore comprises a decoupling component 16 rotatably connected to the pre-chamber gas valve rod component 13 around the first pivot 15 , wherein the contacting surface 14 between the pre-chamber gas valve rod component 13 and the pre-chamber gas valve body 5 is formed by the circumference of the decoupling component 16 .

The advantage of the usage of such a decoupling component 16 is that essentially only linear motions acting along a longitudinal extension of the pre-chamber gas valve body 5 can be transmitted to the pre-chamber gas valve body 5 .

The remaining characteristics of the third embodiment shown by Fig . 8 to 10 are essentially analogous with respect to the second embodiment shown by Fig . 5 to 7 . As it can be seen by the previous Figures and the shown embodiments, it is preferable to use already existing motions of the internal combustion engine for actuating e.g., the prechamber gas valve 2 or other gas vales 26 of the internal combustion engine.

List of used reference signs :

1 pre-chamber assembly

2 pre-chamber gas valve

3 pre-chamber

4 pre-chamber gas valve seat

5 pre-chamber gas valve body

6 mechanical actuation system

7 pre-chamber gas valve rod

8 actuation system

9 pre-chamber gas valve rod component

10 pre-chamber gas valve rod component

11 pre-chamber gas valve rod component

12 pre-chamber gas valve rod component

13 pre-chamber gas valve rod component

14 contact surface

15 first pivot ( of pre-chamber gas valve rod)

16 decoupling component

17 cylinder head

18 second pivot ( of rocker arm)

19 inlet valve

20 outlet valve

21 linear guiding

22 connecting point (push rod)

23 connecting point (pre-chamber gas valve rod)

24 rocker arm

25 counter nut

26 gas valve

27 push rod

28 cam shaft

29 cam

30 valve body

31 valve housing

32 valve seat

33 longitudinal axis

34 cylindrical portion

35 flow passage portion

36 azimuthal guiding regions

37 arc

Claims

Claims :

1. Gas valve for an internal combustion engine, comprising:

- a valve seat (32) , and

- a valve body (30) movable along a longitudinal axis (33) of the valve body (30) , wherein in a closed state of the gas valve (26) the valve body (30) contacts the valve seat (32) at a contact surface, characterized in, that

- adjacent to the valve seat (32) there is provided a cylindrical portion (34) with a first, preferably circular, cross-section,

- the valve body (30) comprises a second, preferably circular, cross-section generally corresponding to the first crosssection, and

- the valve body (30) is at least partially arranged in the cylindrical portion (34) when the gas valve (26) is in the closed state.

2. Gas valve according to claim 1, wherein the valve seat (32) is attached to or provided by a valve housing (31) .

3. Gas valve according to one of the preceding claims, wherein between the cylindrical portion (34) and the valve body (30) a clearance fit is present.

4. Gas valve according to at least one of the preceding claims, wherein, preferably in a valve housing (31) , there is provided at least one gas channel configured to provide air, fuel or air-fuel mixture to be supplied to a target volume via the gap between the cylindrical portion (34) and the valve body

5. Gas valve according to at least one of the preceding claims, wherein the cylindrical portion (34) is provided with such a length, that the valve body (30) clears the cylindrical portion (34) in a position of the valve body (30) relative to the valve seat 20% to 100%, preferably 25 to 100%, particular preferred 25% to 75%, of the longitudinal stroke of the valve body ( 30 ) .

6. Gas valve according to at least one of the preceding claims, wherein the valve body (30) is pre-loaded by an energy storage, preferably a coil spring, against the valve seat (32) .

7. Gas valve according to at least one of the preceding claims, wherein adjacent to the cylindrical portion (34) there is a flow passage portion (35) with a third cross-section which is larger in area than the second cross-section.

8. Gas valve according to claim 7, wherein the third crosssection comprises azimuthally distributed azimuthal guiding regions (36) which generally correspond to the first crosssection and/or the second cross-section in the respective azimuthal guiding region (36) .

9. Gas valve according to claim 7 or 8, wherein the third crosssection is expanded, preferably in the shape of an arc (37) , particularly preferably circular arc, between the azimuthal guiding regions (36) .

10. Gas valve according to at least one of the preceding claims, wherein the guidance of the valve body (30) is effected by a valve housing (31) , preferably at azimuthal guiding regions (36) .

11. Gas valve according to at least one of the preceding claims, wherein the valve body (30) comprises at least one guiding surface extending along the longitudinal axis (33) .

12. Gas valve according to at least one of the preceding claims, wherein the cylindrical portion (34) is provided by a bore.

13. Gas valve according to at least one of the preceding claims, wherein a mechanical actuation system (6) is provided for actuating the gas valve (26) by imparting a motion on the gas valve (26) , preferably the valve body (30) , for opening and/or closing the at least one gas valve (30) .

14. Internal combustion engine comprising gas valve (26) according to the preceding claims.

15. Internal combustion engine according to the preceding claim, wherein there is provided at least one main combustion chamber and a pre-chamber (3) fluidically connected to the at least one main combustion chamber, wherein for suppling air, fuel or air-fuel mixture to the pre-chamber (3) and/or the main combustion chamber the least one gas valve (26) is provided .

16. Internal combustion engine according to claim 15 or 11, wherein a mechanical actuation system (6) is provided for actuating the gas valve (26) by imparting a motion on the gas valve (26) , preferably the valve body (30) , for opening and/or closing the at least one gas valve (26) .

17. Internal combustion engine according to the preceding claim, wherein by the mechanical actuation system (6) a motion of a cam shaft (28) of the internal combustion engine is transformed into an actuation motion of the gas valve (26) .