CN111305976A - Internal combustion engine - Google Patents

Abstract

A two-stroke internal combustion engine having a plurality of cylinders is disclosed, wherein the two-stroke internal combustion engine is configured to inject fuel gas into at least one of the cylinders via a fuel gas supply system. The fuel gas supply system includes one or more fuel gas valves for at least one of the cylinders, the one or more fuel gas valves being configured to inject fuel gas into the cylinder during the compression stroke such that the The fuel gas can mix with the scavenging gas and allow the scavenging gas and fuel gas mixture to be compressed prior to ignition. The one or more fuel gas valves have fuel gas nozzles having one or more nozzle outlets for providing fuel gas to the interior of the cylinder, and wherein the fuel gas nozzles are configured for use in the fuel gas Rotational motion is introduced into the gas.

Description

Internal combustion engine

technical field

The present invention relates to a two-stroke internal combustion engine and a fuel gas valve for the two-stroke internal combustion engine.

Background technique

Two-stroke internal combustion engines are used as propulsion engines in ships such as container ships, bulk carriers, and oil tankers. Reducing unwanted exhaust from internal combustion engines has become increasingly important.

An effective way to reduce the amount of unwanted exhaust is to replace fuel such as heavy fuel oil (HFO) with fuel gas. The fuel gas may be injected into the cylinder at the end of the compression stroke, where it may be immediately ignited by the high temperature to which the gas in the cylinder is compressed or by igniting the pilot fuel. However, injecting fuel gas into the cylinder at the end of the compression stroke requires a large gas compressor to compress the fuel gas prior to injection to overcome the large pressure in the cylinder.

However, large gas compressors are expensive and complex to manufacture and maintain. One way to avoid the use of large compressors is to have a fuel gas valve configured to inject fuel gas at the beginning of the compression stroke when the pressure in the cylinder is significantly lower.

EP 3015679 discloses such a fuel gas valve.

DE 102011003909 discloses an engine with several cylinders, the upper section of which is provided with a discharge valve for exhaust gas and a main injector supplying fuel for diesel mode. Each cylinder is assigned an intake port over the fuel for gas operation and is inserted into the cylinder. If the piston of the respective cylinder is located at the bottom dead center and/or is located in the same positional area as the adjacent area as the piston dead center, the charge air with a relatively low pressure in the combustion chamber of the respective cylinder is introduced for gas operating fuel.

However, it may be difficult to achieve fast and efficient mixing between the scavenging gas and the fuel gas in the cylinder.

A non-homogeneous mixture of fuel gas and scavenge air may result in poor combustion of the fuel gas or even pre-ignition leading to knocking.

One solution could be to inject the fuel gas very early in the compression stroke to allow the gas to mix for a longer time. However, if fuel gas is injected into the cylinder before closing the discharge valve, unwanted fuel gas leakage may result.

Thus, improving the mixing of fuel gas and scavenging gas in the cylinder remains a problem.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention relates to a two-stroke single-flow scavenged crosshead internal combustion engine having a plurality of cylinders, wherein the two-stroke internal combustion engine is configured for injecting fuel gas into the cylinders via a fuel gas supply system. At least one, the fuel gas supply system includes one or more fuel gas valves for the at least one cylinder, the one or more fuel gas valves configured to inject fuel gas into the cylinder during a compression stroke such that the fuel The gas is capable of mixing with the scavenging gas and allowing the mixture of the scavenging gas and fuel gas to be compressed prior to ignition, the one or more fuel gas valves have fuel gas nozzles with fuel gas nozzles for providing fuel gas to the interior of the cylinder One or more nozzle outlets, wherein the fuel gas nozzle is configured to induce rotational motion in the fuel gas.

By introducing rotational motion (ie swirl) in the fuel gas, a jet of fuel gas originating from the opening of the fuel gas nozzle will be inside the cylinder prior to decomposition compared to a corresponding jet of fuel gas without any substantial rotational motion Travel a short distance. This enables the fuel gas to be deposited at desired locations within the cylinder, whereby better mixing can be achieved. This will also allow the fuel gas jet from the relatively large fuel gas outlet to be deposited in the central portion of the cylinder rather than at the cylinder wall opposite the fuel gas outlet, which enables fast injection and good deposition of fuel gas .

The internal combustion engine is preferably a large low speed turbocharged two-stroke crosshead internal combustion engine with single flow scavenging for propulsion of ships with a power of at least 400 kW per cylinder. The internal combustion engine system may include a turbocharger driven by exhaust gas produced by the internal combustion engine and configured to compress the scavenging gas. The internal combustion engine may be a dual-fuel engine with an Otto Cycle mode when running on fuel gas and a Diesel cycle when running on an alternative fuel such as heavy fuel oil or marine diesel. DieselCycle) mode. Such dual fuel engines have their own dedicated fuel supply system for injecting alternative fuels, and this fuel supply system can also be used to inject pilot fuel for igniting the fuel gas and when operating in Otto cycle mode. Scavenge mixture.

An internal combustion engine may include a dedicated ignition system such as a pilot fuel system capable of injecting a small amount of pilot fuel (such as heavy fuel oil or marine diesel) that is accurately measured so that the amount is only sufficient to ignite the fuel gas and scavenge. gas mixture so that only the necessary amount of pilot fuel is used. Such pilot fuel systems are much smaller in size and are more suitable for injecting precise amounts of pilot fuel than dedicated fuel supply systems for alternative fuels, which are not suitable due to the large size of the components for this purpose.

Pilot fuel may be injected into a pre-chamber fluidly connected to a combustion chamber of an internal combustion engine. Alternatively, the mixture of fuel gas and scavenging gas may be ignited by means of a spark plug or laser igniter. Each cylinder may have one or more scavenging inlets at the bottom of the cylinder and a discharge outlet at the top of the cylinder. The fuel gas supply system is preferably configured for injecting fuel gas via the one or more fuel gas valves under sonic conditions (ie speed equal to the speed of sound, ie constant speed). Sonic conditions can be achieved when the pressure drop ratio across the nozzle throat (minimum cross-sectional area) is greater than about two.

In some embodiments, the fuel gas nozzles are configured to induce rotational motion in the fuel gas such that the fuel gas exiting the one or more nozzle outlets will have at least 0.025 at each of the one or more nozzle outlets , a vortex number of at least 0.05 or at least 0.1.

燃料气体速度3D矢量

可以使用比如3D热线风速测定法或粒子图像测速等标准技术来测得。燃料气体速度3D矢量

可以使用计算流体动力学来计算出。这些3D矢量均被分解成沿喷嘴出口轴线所指的轴向部分v_axial、以及沿喷嘴出口表面所指并且与其截面的矢径垂直的切向部分v_tan。随后可以使用以下公式获得涡流数S：Eddy number is a well-defined measure of eddy currents in a fluid. The eddy current number is defined as the ratio of the axial flux of angular momentum to the axial flux of axial momentum. The vortex number can be estimated by first establishing a cylindrical coordinate system at the nozzle exit surface aligned with the geometric nozzle exit axis. Next, the entire nozzle outlet surface is divided into N segments, each segment having a central area A _i , wherein each segment is at a central radial distance _ri from the nozzle outlet axis. Using a larger N will improve the accuracy of the estimation. Within each ith segment, the fuel gas velocity 3D vector is measured or calculated

Fuel gas velocity 3D vector

It can be measured using standard techniques such as 3D hot-wire anemometry or particle image velocimetry. Fuel gas velocity 3D vector

It can be calculated using computational fluid dynamics. These 3D vectors are each decomposed into an axial portion v _axial , pointing along the nozzle exit axis, and a tangential portion v _tan , pointing along the nozzle exit surface and perpendicular to the radii of its cross-section. The eddy current number S can then be obtained using the following formula:

where _RH is the hydraulic diameter given by the section of the nozzle outlet surface divided by the perimeter of the nozzle outlet surface. Note that the above formula always results in Eddy Current Number => 0, regardless of the sign law used in the cylindrical coordinate system.

In some embodiments, the one or more fuel gas valves are configured to be between 0 degrees and 160 degrees from bottom dead center, between 0 degrees and 130 degrees from bottom dead center, or between 0 degrees and 130 degrees from bottom dead center during the compression stroke. The fuel gas is injected into the cylinder when the bottom dead center is 0 degrees to 90 degrees.

Examples of fuel gases are natural gas, methane, ethane and liquefied petroleum gas.

In some embodiments, the fuel gas nozzle includes a flow altering element configured to induce the rotational motion in the fuel gas.

The flow modification element may be an insert or an integral part of the fuel gas nozzle, ie the flow modification element and the fuel gas nozzle may be formed as a single piece.

In some embodiments, the flow altering element is configured to direct the first portion of the gas in a first direction (eg, toward a first inner surface region of the fuel gas nozzle downstream of the flow altering element).

In some embodiments, the flow altering element is further configured to direct the second portion of the fuel gas in a second direction (eg, toward a second inner surface region of the fuel gas nozzle downstream of the flow altering element).

In some embodiments, the flow altering element is further configured to direct the second portion of the fuel gas in a third direction (eg, toward a third inner surface region of the fuel gas nozzle downstream of the flow altering element).

In some embodiments, the flow altering element is further configured to direct the fourth portion of the fuel gas in a fourth direction (eg, toward a fourth inner surface area of the fuel gas nozzle downstream of the flow altering element).

In some embodiments, the flow altering element includes a first passage configured to direct the first portion of the fuel gas in the first direction.

In some embodiments, the flow altering element includes a second passage configured to direct the second portion of the fuel gas in the second direction.

The first channel may be a substantially straight channel extending along a first central axis and the second channel may be a substantially straight channel extending along a second central axis, wherein the first central axis and the second central axis are non-parallel of. The angle between the direction vector of the first central axis and the direction vector of the second central axis may be at least 10 degrees, at least 20 degrees, or at least 30 degrees.

In some embodiments, the flow altering element includes a third channel configured to guide the third portion in a third direction.

In some embodiments, the flow altering element includes a fourth passage configured to direct the fourth portion of the fuel gas in a fourth direction.

The third channel may be a substantially straight channel extending along a third central axis and the fourth channel may be a substantially straight channel extending along a fourth central axis, wherein the third and fourth central axes are not parallel of. The angle between the direction vector of the third central axis and the direction vector of the fourth central axis may be at least 10 degrees, at least 20 degrees, or at least 30 degrees.

In some embodiments, the flow altering element includes a first surface having an angle of incidence of at least 5 degrees, at least 10 degrees, or at least 20 degrees relative to the direction of flow of the fuel gas upstream of the flow altering element.

In some embodiments, the flow altering element includes a second surface having an angle of incidence of at least 5 degrees, at least 10 degrees, or at least 20 degrees relative to the direction of flow of the fuel gas upstream of the flow altering element.

In some embodiments, the flow altering element includes a third surface having an angle of incidence of at least 5 degrees, at least 10 degrees, or at least 20 degrees relative to the direction of flow of the fuel gas upstream of the flow altering element.

In some embodiments, the flow altering element includes a fourth surface having an angle of incidence of at least 5 degrees, at least 10 degrees, or at least 20 degrees relative to the direction of flow of the fuel gas upstream of the flow altering element.

The first, second, third and/or fourth surfaces may be substantially planar surfaces. The first, second, third and/or fourth surfaces may be oriented differently such that the first surface is configured to direct the first portion of the gas towards the first inner surface area of the fuel gas nozzle, the second surface is configured to direct the second portion of the gas toward the second inner surface area of the fuel gas nozzle, the third surface is configured to direct the third portion of the gas toward the third inner surface area of the fuel gas nozzle, and/or The fourth surface is configured to direct the fourth portion of the gas toward the fourth inner surface area of the fuel gas nozzle.

In some embodiments, the fuel gas supply system includes a first nozzle outlet and a second nozzle outlet for at least one of the cylinders, wherein the fuel gas supply system is configured for exiting the first nozzle outlet Rotational motion is introduced into the fuel gas and the second nozzle outlet, and wherein the rotational motion of the fuel gas exiting the first nozzle outlet is stronger than the rotational motion of the fuel gas leaving the second nozzle outlet. Thus, a jet of fuel gas from the first nozzle outlet may travel a shorter distance within the cylinder before disintegrating than a jet of fuel gas from the second nozzle outlet. Thus, the fuel gas from the two jets can be deposited at different locations within the cylinder, thereby resulting in an even more efficient mixing of the fuel gas and scavenging gas.

In some embodiments, the fuel gas supply system includes a first fuel gas valve and a second fuel gas valve for at least one of the cylinders, the first fuel gas valve and the second fuel gas valve being configured to the first fuel gas valve and the second fuel gas valve for injecting fuel gas into the cylinder during the compression stroke so that the fuel gas can mix with the scavenging gas and allow the mixture of scavenging and fuel gas to be compressed prior to ignition There is a fuel gas nozzle, and wherein the first nozzle outlet is the nozzle outlet of the fuel gas nozzle of the first fuel gas valve, and the second nozzle outlet is the nozzle outlet of the fuel gas nozzle of the second fuel gas valve.

In some embodiments, the first fuel gas valve includes a first flow altering element and the second fuel gas valve includes a second flow altering element.

In some embodiments, the fuel gas supply system includes a first fuel gas valve for at least one of the cylinders, the first fuel gas valve configured to inject fuel gas into the cylinder during the compression stroke, enabling the fuel gas to mix with the scavenging gas and allowing the scavenging gas and fuel gas mixture to be compressed prior to ignition, the first fuel gas valve has a fuel gas nozzle, and wherein the first nozzle outlet and the second nozzle outlet are both is the nozzle outlet of the fuel gas nozzle of the first fuel gas valve.

In some embodiments, the fuel gas nozzle of the first fuel gas valve includes a primary passage having an inlet and an outlet, a first secondary passage having an inlet and an outlet, a second secondary passage having an inlet and an outlet, and a primary passage having an inlet, A manifold of first and second outlets, wherein the outlet of the primary channel is connected to the inlet of the manifold, the first outlet of the manifold is connected to the inlet of the first secondary channel, and the second outlet of the manifold is connected to the second outlet The inlet of the secondary channel, the outlet of the first secondary channel is the first nozzle outlet, and the outlet of the second secondary channel is the second nozzle outlet.

In some embodiments, the first secondary channel includes a first flow altering element.

In some embodiments, the second secondary channel includes a second flow altering element, wherein the first flow altering element is configured to induce rotational motion in the gas that is greater than that introduced by the second flow altering element in the gas The rotational motion is stronger.

According to a second aspect, the invention relates to a fuel gas valve for a two-stroke internal combustion engine as disclosed in relation to the first aspect, wherein the fuel gas valve is adapted to inject fuel gas into the cylinder during the compression stroke such that The fuel gas can be mixed with the scavenging gas and allow the mixture of the scavenging and fuel gas to be compressed prior to ignition, the fuel gas valve has a fuel gas nozzle with one or more for supplying the fuel gas to the interior of the cylinder A plurality of nozzle outlets, wherein the fuel gas nozzle is configured to induce rotational motion in the fuel gas.

The different aspects of the invention may be implemented in different ways, including the two-stroke internal combustion engine and fuel gas valve described above and below, each yielding one or more of the benefits and advantages described in connection with at least one of the above-described aspects , and each have one or more preferred embodiments corresponding to the preferred embodiments described in connection with at least one of the aspects described above and/or disclosed in the appended claims. Furthermore, it should be understood that embodiments described in connection with one of the aspects described herein may apply equally to other aspects.

Description of drawings

The above and/or additional objects, features and advantages of the present invention will be further elucidated by the following illustrative and non-limiting detailed description of embodiments of the invention with reference to the accompanying drawings, in which:

Figure 1 schematically shows a cross section of a two-stroke internal combustion engine according to an embodiment of the invention.

Figure 2 schematically shows a cross section of a fuel gas valve 200 for a two-stroke internal combustion engine according to an embodiment of the invention.

Figures 3a-c illustrate a flow modification element 300 according to an embodiment of the invention.

Figure 4 shows a flow modification element 400 according to an embodiment of the present invention.

Figures 5a-b illustrate a flow modifying element 500 according to an embodiment of the present invention.

Detailed ways

In the following description, reference is made to the accompanying drawings, which illustrate, by way of illustration, how the invention may be practiced.

Figure 1 schematically shows a cross-section of a large low-speed turbocharged two-stroke crosshead internal combustion engine 100 with single-flow scavenging for propulsion of a marine vessel according to an embodiment of the present invention. The two-stroke internal combustion engine 100 includes a scavenging system 111 , an exhaust gas receiver 108 and a turbocharger 109 . A two-stroke internal combustion engine has a plurality of cylinders 101 (only a single cylinder is shown in cross section). Each cylinder 101 includes a scavenging inlet 102 for providing scavenging, a piston 103, a discharge valve 104, and one or more fuel gas valves 105 (shown schematically only). The scavenging inlet 102 is fluidly connected to the scavenging system. Piston 103 is shown in its lowest position (bottom dead center). Piston 103 has a piston rod that is connected to a crankshaft (not shown). The fuel gas valve 105 is only shown schematically. A fuel gas valve 105 is configured to inject fuel gas into the cylinder during the compression stroke, enabling the fuel gas to mix with the scavenging gas and allowing the mixture of the scavenging and fuel gas to be compressed prior to ignition, the fuel gas valve 105 having a fuel gas nozzle, The fuel gas nozzle has one or more nozzle outlets for providing fuel gas to the interior of the cylinder. The fuel gas nozzle is configured to induce rotational motion in the fuel gas. The fuel gas valve 105 may be configured to inject fuel gas at the beginning of the compression stroke at 0 to 130 degrees from bottom dead center (ie, when the crankshaft has rotated 0 to 130 degrees from its orientation at bottom dead center) Cylinder 101. Preferably, the fuel gas valve 105 is configured to initiate fuel gas injection after the axis of the crankshaft has rotated a few degrees from bottom dead center such that the piston has moved past the scavenging inlet 102 to prevent the fuel gas from passing through the discharge valve 104 and scavenging The gas inlet 102 exits. The scavenging system 111 includes a scavenging receiver 110 and an air cooler 106 .

Figure 2 schematically shows a cross section of a fuel gas valve 200 for a two-stroke internal combustion engine according to an embodiment of the invention. The fuel gas valve includes a valve shaft 201 , a valve head 202 , a valve seat 203 , and a fuel gas nozzle 204 having a nozzle outlet 206 . The fuel gas nozzles may be provided with flow altering elements 205 (shown only schematically).

Figures 3a-c show a flow modification element 300 according to an embodiment of the invention, wherein Figure 3a shows a front view, Figure 3b shows a top view, and Figure 3c shows a central portion of the flow modification element 300 Perspective view of 301. The flow altering element includes a first passage 302 configured to direct a first portion of the gas in a first direction (eg, toward a first inner surface area of the fuel gas nozzle downstream of the flow altering element 300 ); a second a passage 303, the second passage is configured to direct a second portion of the gas in a second direction (eg, towards a second inner surface area of the fuel gas nozzle downstream of the flow altering element 301); a third passage 304, the first Three passages are configured to direct a third portion of the fuel gas in a third direction (eg, toward a third inner surface area of the fuel gas nozzle downstream of the flow altering element 301 ); and a fourth passage 305 that is configured A fourth portion for directing the fuel gas in a fourth direction (eg, towards a fourth inner surface area of the fuel gas nozzle downstream of the flow altering element 301 ).

Figure 4 shows a flow modification element 400 according to an embodiment of the present invention. The flow altering element comprises a first surface 401 having a first angle of incidence with respect to the flow direction of the fuel gas upstream of the flow altering element 400; a second surface 402 having an angle of incidence relative to the flow altering element 400 a second angle of incidence to the direction of flow of fuel gas upstream 400; a third surface 403 having a third angle of incidence relative to the direction of flow of fuel gas upstream of the flow altering element 400; and a fourth surface 404, The fourth surface has a fourth angle of incidence relative to the flow direction of the fuel gas upstream of the flow altering element 400 . The first, second, third, and fourth angles of incidence are at least 5 degrees, at least 10 degrees, or at least 20 degrees. The first angle of incidence, the second angle of incidence, the third angle of incidence and the fourth angle of incidence may be different or may be the same. The first surface 401, the second surface 402, the third surface 403, the fourth surface 404 are oriented differently such that the first surface 401 is configured to direct the first portion of the gas toward the first inner surface area of the fuel gas nozzle, the first The second surface 402 is configured to direct the second portion of the gas towards the second inner surface area of the fuel gas nozzle and the third surface 403 is configured to direct the third portion of the gas towards the third inner surface area of the fuel gas nozzle , and the fourth surface 404 is configured to direct the fourth portion of the gas toward the fourth inner surface area of the fuel gas nozzle.

Figures 5a-b show a flow modification element 500 according to an embodiment of the invention, wherein Figure 5a shows a top view and Figure 5b shows a perspective view. The flow modification element 500 includes a first channel 501 extending along a centerline 507 having an inlet 503 and an outlet, and a second channel 502 having an inlet and an outlet 505, the first channel 502 extending along the centerline 506 The outlet of 501 is connected to the inlet of the second channel 502, and wherein the angle between the direction vector of the centerline of the first channel 507 and the direction vector of the centerline of the second channel 506 is at least 30 degrees, 60 degrees or 80 degrees , that is, 90 degrees in this embodiment. In addition, the first channel 501 and the second channel are arranged centrally, that is, so that the center line of the first channel 501 does not cross the center line of the second channel 502, for example, the distance between the two center lines 501, 502 may be the first At least 5% of the average diameter of the outlet 505 of the two channels.

Although some embodiments have been described and shown in detail, the invention is not so limited but may be practiced in other ways that fall within the scope of the subject matter defined in the following claims. In particular, it is to be understood that other embodiments may be utilized and structural and functional changes may be made without departing from the scope of the present invention.

In the device claim enumerating several means, several of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used to advantage.

It should be emphasized that, when used in this specification, the term "comprises/comprise" is used to designate the presence of stated features, integers, steps or components, but does not preclude the presence or addition of one or more other Features, entities, steps, parts, or groups thereof.

Claims (10)

1. A two-stroke uniflow scavenging crosshead internal combustion engine (100) having a plurality of cylinders, wherein the two-stroke internal combustion engine (100) is configured for injecting fuel gas into at least one of the cylinders (101) via a fuel gas supply system comprising one or more fuel gas valves (105) for the at least one cylinder configured for injecting fuel gas into the cylinder (101) during a compression stroke so that the fuel gas can be mixed with scavenging gas and allow the mixture of scavenging gas and fuel gas to be compressed before ignition, the one or more fuel gas valves (105) having a fuel gas nozzle (204) with one or more nozzle outlets (206) for providing fuel gas to the interior of the cylinder, characterized in that, the fuel gas nozzle (204) is configured to introduce a rotational motion in the fuel gas.

2. A two-stroke internal combustion engine according to claim 1, wherein the fuel gas nozzle (204) comprises a flow-altering element (205) configured to induce the rotational movement in the fuel gas.

3. A two-stroke internal combustion engine according to claim 1 or 2, wherein the flow-altering element (205) is configured for directing the first portion of the fuel gas in a first direction.

4. A two-stroke internal combustion engine according to claim 3, wherein the flow-changing element (205) is further configured to direct the second portion of the fuel gas in a second direction.

5. A two-stroke internal combustion engine according to claim 3 or 4, wherein the flow-changing element (300) comprises a first channel (302) configured for guiding a first portion of the fuel gas in the first direction.

6. The two-stroke internal combustion engine according to any one of claims 2 to 5, wherein the flow-changing element (400) comprises a first surface (401) having an angle of incidence of at least 5 degrees, at least 10 degrees or at least 20 degrees with respect to the flow direction of the fuel gas upstream of the flow-changing element.

7. The two-stroke internal combustion engine according to any one of claims 1 to 6, wherein the fuel gas supply system comprises a first nozzle outlet and a second nozzle outlet for at least one of the cylinders, wherein the fuel gas supply system is configured to introduce a rotational motion in the fuel gas exiting the first nozzle outlet and the second nozzle outlet such that the rotational motion of the fuel gas exiting the first nozzle outlet is stronger than the rotational motion of the fuel gas exiting the second nozzle outlet.

8. The two-stroke internal combustion engine of claim 7, wherein the fuel gas supply system includes first and second fuel gas valves for at least one of the cylinders, the first and second fuel gas valves configured to inject fuel gas into the cylinder during the compression stroke so that the fuel gas can mix with scavenging gas and allow a mixture of scavenging gas and fuel gas to be compressed prior to ignition, the first and second fuel gas valves having fuel gas nozzles, and wherein the first nozzle outlet is a nozzle outlet of a fuel gas nozzle of the first fuel gas valve and the second nozzle outlet is a nozzle outlet of a fuel gas nozzle of the second fuel gas valve.

9. The two-stroke internal combustion engine of claim 7, wherein the fuel gas supply system includes a first fuel gas valve for at least one of the cylinders configured to inject fuel gas into the cylinder during the compression stroke so that the fuel gas can mix with scavenging gas and allow a mixture of scavenging gas and fuel gas to be compressed prior to ignition, the first fuel gas valve having a fuel gas nozzle, and wherein the first nozzle outlet and the second nozzle outlet are both nozzle outlets of the fuel gas nozzle of the first fuel gas valve.

10. A fuel gas valve for a two-stroke internal combustion engine according to any one of claims 1 to 9, wherein the fuel gas valve (105) is adapted to inject fuel gas into the cylinder during the compression stroke such that the fuel gas can mix with scavenging gas and allow the mixture of scavenging gas and fuel gas to be compressed before ignition, the fuel gas valve (105) having a fuel gas nozzle (204), the fuel gas nozzle (204) having one or more nozzle outlets (206) for providing fuel gas to the interior of the cylinder, wherein the fuel gas nozzle (204) is configured to introduce rotational motion in the fuel gas.

Images