JP2023029298A - internal combustion engine - Google Patents

Abstract

To provide a two-stroke uniflow scavenging cross head internal combustion engine including at least one cylinder, a cylinder cover, a piston, a fuel gas supply system connectable to a fuel gas tank, and a scavenging system.SOLUTION: A fuel gas supply system includes a first fuel gas valve constituted to allow a fuel gas to enter a main combustion chamber defined between a piston and a cylinder cover during a compression stroke to the cylinder via a fuel gas nozzle. The first fuel gas valve is at least partially disposed in the cylinder cover, a nozzle of the first fuel gas valve has a first nozzle opening constituted to inject the fuel gas along a first nozzle shaft, and the first nozzle shaft forms an angle with respect to an axial direction.SELECTED DRAWING: Figure 3a

Description

The present invention relates to two-stroke internal combustion engines.

Two-stroke internal combustion engines are used as propulsion engines in ships such as container ships, bulk carriers, and tankers. Reducing unwanted emissions from internal combustion engines is becoming increasingly important.

An effective way to reduce the amount of unwanted emissions is to switch from fuel oil, eg heavy fuel oil (HFO), to fuel gas. The fuel gas may be injected into the cylinder at the end of the compression stroke and can be ignited immediately by the high temperature the gas in the cylinder attains as it is compressed or by ignition of the pilot fuel. However, injecting the fuel gas into the cylinder at the end of the compression stroke requires a high pressure gas compressor to compress the fuel gas prior to injection in order to overcome the high pressure in the cylinder.

However, high pressure gas compressors are expensive and complex to manufacture and maintain. One way to avoid the need for a high pressure compressor 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.

DK176118B discloses such an engine in which the gas is injected into the scavenging inlet or directly into the cylinder through the cylinder wall.

WO2013007863 discloses another example of such an engine in which gas is injected directly into the cylinder through the cylinder wall.

Ensuring fast and efficient mixing between scavenging air and fuel gas in the cylinder can be difficult.

Having a non-homogeneous mixture of fuel gas and scavenging air may result in incomplete combustion of the fuel gas or even pre-ignition leading to knocking.

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

According to a first aspect, the present invention relates to a two-stroke uniflow scavenging crosshead internal combustion engine comprising at least one cylinder, a cylinder cover, a piston and a fuel gas tank connectable to a fuel gas tank. a supply system and a scavenging system, a cylinder having a cylinder wall, a cylinder cover located at the upper end of the cylinder and having an exhaust valve, and a piston centered between bottom dead center and top dead center; Moveably disposed within the cylinder along the axis, the scavenging system has a scavenging inlet located at the bottom of the cylinder, and a fuel gas supply system mixes fuel gas with scavenging air from the scavenging inlet for the cylinder. During the compression stroke, the fuel gas is forced into a main defined space between the piston and the cylinder cover through a fuel gas nozzle that allows the mixture of scavenging air and fuel gas to be compressed before it is ignited. a first fuel gas valve configured to enter the combustion chamber, the first fuel gas valve being disposed at least partially in the cylinder cover; It has a first nozzle opening configured to inject fuel gas along a nozzle axis, the first nozzle axis being angled with respect to the axial direction.

As a result, by locating the fuel gas valve in the cylinder cover and angling the fuel gas nozzle with respect to the axial direction, the resulting fuel gas jet impinges on a large portion of the cylinder wall, resulting in a mixture of fuel gas and scavenging air. Provides a homogenous mixture.

The internal combustion engine is preferably a large slow turbocharged two-stroke crosshead internal combustion engine with uniflow scavenging for propelling a vessel with at least 400 kW of power per cylinder. The internal combustion engine may include a turbocharger driven by the exhaust gas produced by the internal combustion engine and configured to compress the scavenging air. The internal combustion engine may be a dual fuel engine having an Otto cycle mode when fueled with fuel gas and a Diesel cycle mode when fueled with an alternative fuel such as heavy oil or marine diesel oil. Such a dual fuel engine has its own dedicated fuel supply system for injecting the alternative fuel, which in Otto cycle mode for igniting the mixture of fuel gas and scavenging air. When operating, it may also be used for injection of pilot fuel.

The internal combustion engine can ignite just the right amount of fuel gas and scavenging air mixture to use only the required amount of pilot fuel. Capable of injecting precisely measured small amounts of pilot fuel, such as heavy oil or marine diesel. It may also have a dedicated ignition system, such as a pilot fuel system. Such pilot fuel systems are smaller in size and more suitable for injecting precise amounts of pilot fuel compared to dedicated fuel delivery systems for alternative fuels, since the large size of the components is useful for this purpose. by not being suitable for

Pilot fuel may be injected in a preheat chamber that is fluidly connected to the combustion chamber of the internal combustion engine. Alternatively, the mixture of fuel gas and scavenging air may be ignited by means comprising a spark plug or laser igniter. Each cylinder may be provided with one or more scavenging inlets at the bottom of the cylinder and an exhaust at the top of the cylinder.

The fuel gas supply system is preferably arranged to inject fuel gas through one or more fuel gas valves under sonic conditions, i.e. at a velocity equal to the speed of sound, i.e. constant velocity. ing. A sonic state may be achieved when the pressure drop ratio across the nozzle throat (smallest area of the cross section) is greater than approximately two.

The central shaft extends axially. The entire first fuel gas valve may be arranged in the cylinder cover. Alternatively, only part of the first fuel gas valve may be arranged in the cylinder cover, for example the nozzle may be arranged in the cylinder cover and the remaining fuel gas valve part It may be arranged outside the cylinder cover. However, some of the fuel gas nozzles may also be located outside the cylinder cover, for example the most distal ends of the fuel gas nozzles may protrude into the main combustion chamber as further described below. The nozzle of the first fuel gas valve may have a distal portion extending along the first nozzle axis, e.g., the distal portion is a tube centered about the first nozzle axis. It may have a shape.

In some embodiments, the angle between the first nozzle axis and the axial direction is between 5 and 50 degrees, between 10 and 40 degrees, or between 15 and 30 degrees.

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

In some embodiments, the cylinder has a first portion and a second portion separated by a reference plane extending along the central axis, and at least a portion of the nozzle of the first fuel gas valve comprises: Disposed in the cylinder cover over the first portion of the cylinder, the first nozzle shaft has an upper portion extending into the first portion of the cylinder and a lower portion extending into the second portion of the cylinder.

As a result, by having a first fuel gas valve positioned over the first portion of the cylinder and configured to inject the fuel gas toward the second portion of the cylinder, the resulting fuel gas jets strike the cylinder wall with a high radial motion that can help distribute the fuel gas through the main combustion chamber.

The first and second portions of the cylinder can have equal sizes. The first nozzle axis has a radial component and an axial component, and the reference plane is oriented perpendicular to the radial component of the first nozzle axis. The first nozzle shaft may optionally also have a connecting component.

In some embodiments, the bottom dead center piston is located under both the top and bottom of the first nozzle axis, and the top dead center piston is located over the entire bottom of the first nozzle axis. and the first fuel gas valve is configured to initiate fuel gas injection during the previous compression stroke when the piston is over the entire lower portion of the first nozzle axis.

The resulting jet of fuel gas can therefore impinge on the cylinder wall prior to movement of the piston during the compression stroke preventing access to that portion of the cylinder wall.

The first fuel gas valve may be configured to initiate fuel gas injection during the compression stroke before the piston reaches the bottom of the first nozzle axis. The first fuel gas valve may inject fuel gas for an injection period, the injection period ending before the piston is over the entire lower portion of the first nozzle axis.

In some embodiments, the fuel gas supply system comprises a second fuel gas valve having a fuel gas nozzle for the cylinder, the second fuel gas valve disposed at least partially in the cylinder cover and the second fuel gas valve having a fuel gas nozzle. has a first nozzle opening configured to inject fuel gas along a second nozzle axis, the second nozzle axis angled with respect to the axial direction None.

The second fuel gas valve may correspond to the first fuel gas valve.

In some embodiments, at least a portion of the nozzle of the second fuel gas valve is positioned in the cylinder cover over the second portion of the cylinder and the second nozzle axis extends into the second portion of the cylinder. It has an upper portion that extends and a lower portion that extends into the first portion of the cylinder.

As a result, the first fuel gas valve positioned over the first portion of the cylinder directing the fuel gas towards the second portion of the cylinder and the cylinder directing the fuel gas towards the first portion of the cylinder. Having the second fuel gas valve positioned above the second portion of the provides particularly effective mixing of the fuel gas and scavenging air.

In some embodiments, the piston at bottom dead center is located under both the top and bottom of the second nozzle axis, and the piston at top dead center is located over the entire bottom of the second nozzle axis. and the second fuel gas valve is configured to initiate injection of fuel gas during the previous compression stroke when the piston is over the entire lower portion of the second nozzle axis.

The second fuel gas valve may be configured to initiate fuel gas injection during the compression stroke before the piston reaches the bottom of the second nozzle axis. The second fuel gas valve may inject fuel gas for an injection period that ends before the piston is over the entire lower portion of the second nozzle axis.

In some embodiments, the first nozzle axis intersects the second nozzle axis.

As a result, the jets emanating from the first fuel gas valve collide with the jets emanating from the second fuel gas valve, thereby providing improved mixing of the fuel gas and scavenging air.

In some embodiments, the first fuel gas valve is configured to initiate fuel gas injection prior to closing the exhaust valve.

If the fuel gas exiting the fuel gas nozzle has a sufficiently high motion, it is possible to begin fuel gas injection long before the exhaust valve closes without causing significant direct leakage of fuel gas through the exhaust valve. Applicant has discovered that there is. High fuel gas motion may be achieved by ensuring fuel gas is injected under sonic conditions and by using nozzles with large throats.

In some embodiments, the engine has a stroke of X mm and the first nozzle opening of the nozzle of the first fuel gas valve has a diameter of Y, where Y is 1% to 4% of X. Between.

As a result, using a nozzle with a diameter of 1% to 4% of the hole size (larger diameter) ensures that the fuel gas is injected with high motion.

In some embodiments, the first fuel gas valve is configured to begin injecting fuel gas 95 degrees, 90 degrees or 85 degrees before bottom dead center.

As a result, starting injection earlier provides more times to allow the fuel gas to mix with the scavenging air.

In some embodiments, the first fuel gas valve is configured to begin injecting fuel gas 40 degrees, 50 degrees, or 60 degrees after bottom dead center.

As a result, it can be ensured that no fuel gas leaks directly from the open exhaust valve or that only a small amount of fuel gas is allowed.

In some embodiments, the nozzle of the first fuel gas valve protrudes into the main combustion chamber and the first fuel gas valve is configured to initiate fuel gas injection before the exhaust valve is closed. there is

As a result, fuel gas injection may begin sooner without resulting in increased direct gas leakage through the exhaust valve.

In some embodiments, the exhaust valve has a valve plate, the valve plate is movable along a central axis between a closed position and an open position, and the exhaust valve plate is positioned at the first position in the closed position. and at a second height in an open position, the first height being higher than the second height and the distal end of the nozzle being below the second height, i.e. Located below the level of the exhaust valve when the exhaust valve is open.

In some embodiments, the exhaust valve has a valve plate, the valve plate is movable along the exhaust valve axis between a closed position and an open position, and the first nozzle opening is centered on the central axis. and the center of the valve plate of the exhaust valve is positioned at a second distance to the central axis, the second distance being greater than the first distance.

As a result, by off-centering the exhaust valves, the first fuel gas valve can accept more central positions in the cylinder cover. This allows the ignition system to be placed in a more central location, for example in the preheat chamber, or a set of preheat chambers in which the central exhaust is located.

The exhaust valve axis may be parallel to the central axis, whereby the distance from the center of the valve plate to the central axis corresponds to the distance between the central axis and the exhaust valve axis. The cylinder cover may have a plurality of eccentric exhaust valves, for example at least 2, at least 3 or at least 4 eccentric exhaust valves. The first distance may be less than 25% of the inner diameter of the cylinder.

In some embodiments, the fuel gas valve is configured to inject fuel gas for an injection period, the injection period being less than the time it takes to rotate the crank angle 30 degrees.

In some embodiments, the first fuel gas valve has a second nozzle opening configured to inject fuel gas along a third nozzle axis, the third nozzle axis comprising: Angular with respect to the axial direction, the angle between the third nozzle axis and the axial direction is greater than the angle between the first nozzle axis and the axial direction.

As a result, a better distribution of the fuel gas can be achieved since the secondary nozzle openings ensure that the fuel gas is provided to the top of the main combustion chamber.

Different aspects of the invention can be implemented in different ways, including a two-stroke uniflow scavenging crosshead internal combustion engine as described above and as follows, each described in relation to at least one of the above aspects. resulting in one or more of the benefits and advantages described above, each corresponding to a preferred embodiment described in connection with at least one of the above aspects and/or disclosed in the dependent claims. It has more than one preferred embodiment. Furthermore, it will be appreciated that an embodiment described in relation to one of the aspects described herein may be equally applicable to other aspects.

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 present invention with reference to the accompanying drawings. .

FIG. 1 schematically shows a cross-section of a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the invention. Figure 2 schematically shows a cross-section of a fuel gas valve for a two-stroke internal combustion engine according to an embodiment of the invention. Figure 3a schematically shows a cross-section of a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the invention. Figure 3b schematically shows a cross-section of a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the invention. Figure 3c schematically shows a cross-section of a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the invention. FIG. 4 schematically shows a cross-section of a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the invention. Figure 5 schematically shows the upper end of a cylinder provided with a cylinder cover according to an embodiment of the invention. Figure 6 schematically illustrates a fuel gas valve, according to an embodiment of the invention.

In the following description, reference is made to the accompanying drawings which show, by way of example, how the invention can be implemented.

FIG. 1 schematically shows a cross-section of a two-stroke uniflow scavenging crosshead internal combustion engine 100 for propelling a marine vessel according to an embodiment of the invention. The two-stroke internal combustion engine 100 comprises a scavenging system 111 , an exhaust gas receiver 108 and a turbocharger 109 . The two-stroke internal combustion engine has a plurality of cylinders 101 (only one cylinder is shown in cross section). Each cylinder 101 has a scavenging air inlet 102 located in the lower section of the cylinder to provide scavenging air, a piston 103, a cylinder cover 112 located at the upper end of the cylinder, an exhaust valve 104 located in the cylinder cover, and 1 One or more fuel gas valves 105 (shown only schematically) are provided. The scavenging air 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 connected to a crankshaft (not shown). A piston 103 is movably disposed within the cylinder along a central axis 113 between bottom dead center and top dead center. Central shaft 113 extends axially. Fuel gas valve 105 directs fuel gas between piston 103 and cylinder cover 112 during the compression stroke via a fuel gas nozzle (not shown) that allows the fuel gas to mix with scavenging air. It is configured to enter the main combustion chamber. The fuel gas valve 105 is at least partially disposed in the cylinder cover 112 and the nozzle of the fuel gas valve is a first nozzle configured to inject fuel gas along a first nozzle axis 150 . It has an opening (not shown). The first nozzle axis 150 is angled with respect to the axial direction. As a result, the placement of the fuel gas valve 105 in the cylinder cover 120 and the angling of the fuel gas nozzle with respect to the axial direction causes the resulting fuel gas jet to impinge on most of the cylinder wall, resulting in results in a homogeneous mixture of fuel gas and scavenging air.

Internal combustion engine 100 includes a dedicated ignition system 116 for igniting the mixture of fuel gas and scavenging air at the end of the compression stroke. By way of example, a dedicated ignition system may be a pilot fuel system capable of injecting a precisely measured small amount of pilot fuel, such as heavy oil or marine diesel, and only the required amount of pilot fuel is used. As such, just the amount is capable of igniting the mixture of fuel gas and scavenging air. Such pilot fuel systems are smaller in size and better suited to injecting the appropriate amount of pilot fuel compared to dedicated fuel delivery systems for alternative fuels, since the larger size of the components is useful for this purpose. by not being suitable for Pilot fuel may be injected in a preheat chamber that is fluidly connected to the combustion chamber of the internal combustion engine. Alternatively, the pilot fuel may be injected in a preheating chamber set fluidly connected to the combustion chamber of the internal combustion engine. The fuel gas valve 105 may be configured to start injecting fuel gas 95 degrees, 90 degrees, or 85 degrees before bottom dead center. The first fuel gas valve may be configured to begin injecting fuel gas 40 degrees, 50 degrees, or 60 degrees after bottom dead center.

The scavenging air system 111 includes a scavenging air receiver 110 and an air cooler 106 . The exhaust valves are located in the center of the cylinder cover, e.g. Timing can be variable.

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. Although the fuel gas valve 200 in the figures is shown in a horizontal position, it may be positioned at any angle to the axial direction. The fuel gas valve 200 comprises a valve shaft 201 , a valve plate 202 , a valve seat 203 and a fuel gas nozzle 204 having a first nozzle opening 206 . The fuel gas valve 200 shown has a single nozzle opening, but may have multiple nozzle openings. The valve shaft 201 and valve plate 202 are positioned between a closed position in which fuel gas is prevented from flowing through the fuel gas valve 200 and an open position in which fuel gas is allowed to flow through the fuel gas valve 200. It is movable. Valve shaft 201 and valve plate 202 are shown in the closed position in FIG. The valve shaft 201 and valve plate 202 are movable between closed and open positions by an actuator (not shown) controlled by a control unit (not shown). First nozzle openings 206 are configured to inject fuel gas along first nozzle axis 205 .

Figures 3a-3c schematically show a cross-section of a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the invention, Figure 3a showing the engine with the piston at bottom dead center and Figure 3b , shows the engine with the piston in the middle of the compression stroke, and FIG. 3c shows the engine with the piston at top dead center. A two-stroke uniflow scavenging crosshead internal combustion engine comprises at least one cylinder 115, a cylinder cover 112, a piston 103, a fuel gas supply system connectable to a fuel gas tank, and a scavenging system (not shown). The cylinder has a cylinder wall, a cylinder cover 112 is located at the upper end of the cylinder 115, has an exhaust valve 104, and a piston 103 is positioned along a central axis 113 between bottom dead center and top dead center. It is movably arranged in the cylinder 115 . Central shaft 113 extends axially. A scavenging air system having a scavenging air inlet 102 is located at the bottom of the cylinder 115 and a fuel gas supply system allows the fuel gas to mix with the scavenging air from the scavenging inlet 102 to the cylinder and mix with the scavenging air before being ignited. A second fuel gas configured to enter the main combustion chamber defined between the piston 103 and the cylinder cover 112 during the compression stroke via a fuel gas nozzle that allows the fuel gas mixture to be compressed. 1 fuel gas valve 105 is provided. First fuel gas valve 105 is at least partially located in cylinder cover 112 . The nozzle of the first fuel gas valve 105 has a first nozzle opening configured to inject fuel gas along a first nozzle axis 150 . The first nozzle axis 150 is at an angle 157 with respect to the axial and central axis. In this embodiment the angle is approximately 22 degrees. However, in other embodiments, the angle between the first nozzle axis and the axial direction is between 5 and 50 degrees, between 10 and 40 degrees, or between 15 and 30 degrees. First nozzle axis 150 has a radial component 155 and an axial component 156 . Cylinder 115 has a first portion 160 and a second portion 161 separated by a reference plane 151 extending along central axis 113 . The reference plane 151 is arranged perpendicular to the radial component 155 of the first nozzle axis 150, ie the reference plane 151 is also perpendicular to the plane of the drawing. The nozzle of the first fuel gas valve 150 is located in the cylinder cover 112 over the first portion of the cylinder 160 and the first nozzle axis 150 extends into the first portion of the cylinder (inside the cylinder). It has an upper portion 170 that extends and a lower portion 171 that extends to the second portion of the cylinder (inside the cylinder). The piston 103 at bottom dead center is located below both the top 170 and the bottom 171 of the first nozzle shaft 150 (see FIG. 3a), and the piston 103 at top dead center is located below the first nozzle shaft 150. 171 (see FIG. 3c). The first fuel gas valve 105 allows the injection of fuel gas during the compression stroke before the piston 103 reaches the lower part 171 of the first nozzle axis, i.e. before the piston 103 reaches the piston shown in Figure 3b. configured to start. As a result, by having the first fuel gas positioned over the first portion of the cylinder and configured to inject the fuel gas toward the second portion of the cylinder, the resulting fuel gas The jets can strike the cylinder walls with high radial motion to help distribute the fuel gas through the main combustion chamber.

FIG. 4 schematically shows a cross-section of a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the invention. The embodiment corresponds to the embodiment disclosed in connection with FIGS. 3a-3c with the difference that the fuel gas supply system further comprises a second fuel gas valve 190 with a fuel gas nozzle for the cylinder. do. A second fuel gas valve 190 is disposed at least partially in the cylinder cover 112 and the nozzle of the second fuel gas valve is configured to inject fuel gas along the second nozzle axis 152 . It has a first nozzle opening that is The second nozzle axis 152 is angled with respect to the axial direction. At least a portion of the nozzle of the second fuel gas valve 190 is positioned in the cylinder cover 112 over the cylinder second portion 161 and the second nozzle axis extends into the second portion of the cylinder 161 . and a lower portion 174 extending into the first portion of the cylinder 160 . The piston 103 at bottom dead center is located under both the upper portion 173 and the lower portion 174 of the second nozzle shaft 152 . The piston 103 at top dead center is positioned over the entire lower portion 174 of the second nozzle shaft 152 . The second fuel gas valve 190 is configured to initiate fuel gas injection during the compression stroke before the piston 103 reaches the lower portion 174 of the second nozzle shaft 152 . As a result, the first fuel gas valve 105 located on the first part 160 of the cylinder directing the fuel gas towards the second part of the cylinder 161 and the first part of the cylinder 160 Having a second fuel gas valve 190 positioned over the second portion of the cylinder 160 to direct the fuel gas results in particularly effective mixing of the fuel gas and scavenging air. In this embodiment, first nozzle axis 150 intersects second nozzle axis 152 . As a result, the jets emanating from the first fuel gas valve 105 collide with the jets emanating from the second fuel gas valve 190, leading to improved distribution of the fuel gas in the cylinder, thereby improving fuel gas and scavenging. resulting in a good mixture.

FIG. 5 schematically shows the upper end of cylinder 115 provided with cylinder cover 112, according to an embodiment of the invention. First fuel gas valve 105 is at least partially located in cylinder cover 112 . The first fuel gas valve 105 has a nozzle 195 . The first fuel gas valve nozzle 195 has a first nozzle opening configured to inject fuel gas along a first nozzle axis 150 angled with respect to the axial direction. there is The cylinder cover 112 has an exhaust valve 104 . The nozzle 195 of the first fuel gas valve 105 protrudes into the main combustion chamber and the first fuel gas valve 105 is configured to begin injecting fuel gas before the exhaust valve 104 closes. An exhaust valve having a valve plate is movable along a central axis between a closed position and an open position, the exhaust valve plate having a first height in the closed position and a second height in the open position. are placed in Exhaust valve 104 is shown in FIG. 5 with the valve plate in the open position. The first height is greater than the second height, and the distal end of nozzle 195 is positioned below the second height, i.e., below the height of the exhaust valve plate when the exhaust valve is open. ing. As a result, fuel gas injection may begin sooner without resulting in increased direct gas leakage through the exhaust valve.

FIG. 6 schematically illustrates fuel gas valve 105, according to an illustrative embodiment of the invention. A fuel gas valve 105 is located at least partially in the cylinder cover and has a nozzle. The nozzle of the fuel gas valve 105 has a first nozzle opening 195 configured to inject fuel gas along a first nozzle axis 150 angled with respect to the axial direction 156 . . The nozzle of the fuel gas valve 105 further has a second nozzle opening 196 configured to inject fuel gas along a third nozzle axis 199 . A third nozzle axis 199 is angled with respect to the axial direction 156 . The angle between third nozzle axis 199 and axial direction 156 is greater than the angle between first nozzle axis 150 and axial direction 156 . As a result, better axial distribution of the fuel gas can be achieved as the second nozzle openings 196 can ensure that the fuel gas is provided to the upper part of the combustion chamber. The first nozzle openings 195 may be larger than the second nozzle openings 196 because the first nozzle openings 195 may distribute the fuel gas to a greater portion of the main combustion chamber than the second nozzle openings 196. good.

Although several embodiments have been described and illustrated in detail, the invention is not so limited and may be embodied otherwise within the subject matter defined in the following claims. may 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 a device claim enumerating several means, several of these means can be embodied by one and the same item of hardware. The mere fact that certain measures are recited in mutually different dependent claims or in different embodiments does not indicate that a combination of these measures cannot be used to advantage.

As used herein, the term "comprising/comprising" is to be interpreted to specify the presence of the stated feature, integer, step, or component, but not one or more other features. It should be emphasized that it does not exclude the presence or addition of , integers, steps, components, or groups thereof.

Claims (15)

A two-stroke uniflow scavenging crosshead internal combustion engine comprising at least one cylinder, a cylinder cover, a piston, a fuel gas supply system connectable to a fuel gas tank, and a scavenging system,
The cylinder has a cylinder wall, the cylinder cover is located at the upper end of the cylinder and has an exhaust valve, and the piston extends along the central axis between bottom dead center and top dead center. Moveably disposed within a cylinder, the scavenging system having a scavenging inlet located at the bottom of the cylinder, and the fuel gas supply system for mixing fuel gas with scavenging air from the scavenging inlet to the cylinder. Fuel gas is defined between the piston and the cylinder cover during the compression stroke via a fuel gas nozzle that allows the mixture of scavenging air and fuel gas to be compressed before it is ignited. a first fuel gas valve configured to enter the primary combustion chamber with the
The first fuel gas valve is disposed at least partially in the cylinder cover, and a nozzle of the first fuel gas valve is configured to inject fuel gas along a first nozzle axis. 2. A two-stroke uniflow scavenging crosshead internal combustion engine having a first nozzle opening that extends downward, said first nozzle axis being angled with respect to an axial direction. The cylinder has a first portion and a second portion separated by a reference plane extending along the central axis, and at least a portion of the nozzle of the first fuel gas valve extends from the first portion of the cylinder. and said first nozzle shaft has an upper portion extending into a first portion of said cylinder and a lower portion extending into a second portion of said cylinder. 2. A two-stroke uniflow scavenging crosshead internal combustion engine according to claim 1. The bottom dead center piston is located under both the top and bottom of the first nozzle shaft, the top dead center piston is located over the entire bottom of the first nozzle shaft, and the 3. The method of claim 2, wherein the first fuel gas valve is configured to initiate fuel gas injection during the compression stroke before the piston is over the entire lower portion of the first nozzle axis. A two-stroke uniflow scavenging crosshead internal combustion engine as described. The fuel gas supply system comprises a second fuel gas valve having a fuel gas nozzle for the cylinder, the second fuel gas valve being disposed at least partially in the cylinder cover and the second fuel gas valve having a fuel gas nozzle. has a first nozzle opening configured to inject fuel gas along a second nozzle axis, said second nozzle axis being angled with respect to the axial direction; 4. A two-stroke uniflow scavenging crosshead internal combustion engine according to claim 2 or 3, comprising: At least a portion of the nozzle of the second fuel gas valve is positioned in a cylinder cover over the second portion of the cylinder, the second nozzle axis extending into the second portion of the cylinder. and a lower portion extending into the first portion of said cylinder. The piston at bottom dead center is located under both the top and bottom of the second nozzle axis, the piston at top dead center is located over the entire bottom of the second nozzle axis, and 6. The method of claim 5, wherein a second fuel gas valve is configured to initiate injection of fuel gas during said compression stroke prior to said piston being over the entire lower portion of said second nozzle axis. A two-stroke uniflow scavenging crosshead internal combustion engine as described. 7. The two-stroke uniflow scavenging crosshead internal combustion engine of claim 6, wherein said first nozzle axis intersects said second nozzle axis. 8. The two-stroke uniflow scavenging crosshead internal combustion engine of any preceding claim, wherein said first fuel gas valve is configured to initiate fuel gas injection prior to closing said exhaust valve. institution. wherein said engine has a stroke of X mm and said first nozzle opening of said first fuel gas valve nozzle has a diameter of Y, Y being between 1% and 4% of X. 9. The two-stroke uniflow scavenging crosshead internal combustion engine according to Item 8. 10. The two-stroke of claim 8 or 9, wherein 95 degrees before, 90 degrees or 85 degrees before bottom dead center, the first fuel gas valve is arranged to start injecting fuel gas. Uniflow scavenging crosshead internal combustion engine. A nozzle of said first fuel gas valve projects into said main combustion chamber, said first fuel gas valve being configured to initiate injection of fuel gas before said exhaust valve is closed. 11. The two-stroke uniflow scavenging crosshead internal combustion engine according to any one of Items 1 to 10. The exhaust valve has a valve plate movable along a central axis between a closed position and an open position, the exhaust valve plate positioned at a first height in the closed position. and at a second height in the open position, the first height being higher than the second height and the distal end of the nozzle being positioned below the second height. 12. The two-stroke uniflow scavenging crosshead internal combustion engine of claim 11 . The exhaust valve has a valve plate, the valve plate is movable along an exhaust valve axis between a closed position and an open position, and the center of the first nozzle opening is the first nozzle opening to the central axis. and the center of the valve plate of the exhaust valve is positioned at a second distance to the central axis, the second distance being greater than the first distance. A two-stroke uniflow scavenging crosshead internal combustion engine according to any one of the preceding claims. 14. Any of claims 1 to 13, wherein the first fuel gas valve is configured to inject fuel gas for an injection period, the injection period being less than the time it takes to rotate the crank angle by 30 degrees. 2. A two-stroke uniflow scavenging crosshead internal combustion engine according to claim 1. The first fuel gas valve has a second nozzle opening configured to inject fuel gas along a third nozzle axis, the third nozzle axis being 15. Any of claims 1 to 14, wherein the angle between the third nozzle axis and the axial direction is greater than the angle between the first nozzle axis and the axial direction. 2. A two-stroke uniflow scavenging crosshead internal combustion engine according to claim 1.

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