JP6911182B2 - Internal combustion engine - Google Patents

Description

The present invention relates to a two-stroke uniflow scavenging crosshead internal combustion engine and a prefuel chamber.

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, such as heavy oil (HFO), to fuel gas. The fuel gas can be injected into the cylinder at the end of the compression stroke where it can be ignited immediately, either by the high temperature achieved by the gas in the cylinder when compressed or by the ignition of 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 in order 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 need for large compressors is to configure the engine to inject fuel gas at the beginning of a compression stroke where the pressure in the cylinder is significantly lower.

WO2013007863 discloses such an institution. A pilot ignition pre-combustion chamber is provided on the cylinder cover to ensure proper ignition of the fuel gas. A certain amount of pilot fuel oil is injected into the pilot ignition pre-combustion chamber, which is then self-ignited by the temperature and pressure in the pilot ignition pre-combustion chamber. This provides a torch that ignites the fuel gas in the main chamber of the cylinder.

However, injecting a certain amount of pilot fuel oil requires a dedicated fuel oil supply system that increases the amount of unwanted emissions and complicates the engine. In addition, in a dual fuel engine with both a fuel gas supply system and a fuel oil supply system, the additional reliability of having two fuel systems is partly if the engine cannot function without the fuel oil supply system. Is lost.

Therefore, providing an improved two-stroke internal combustion engine remains a challenge.

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, a fuel gas supply system and a scavenging system. It has a wall, the cylinder cover is located at the top of the cylinder and has a discharge valve, and the piston is movably located in the cylinder along the central axis between the bottom dead point and the top dead point. The scavenging system has a scavenging inlet located at the bottom of the cylinder, and the fuel gas supply system is configured to be at least partially located on the cylinder wall and inject fuel gas into the cylinder during the compression stroke. Equipped with a fuel gas valve, the fuel gas can be mixed with the scavenger, allowing the mixture of the scavenger and the fuel gas to be compressed before being ignited, where the engine is in the pre-fuel chamber. And a pilot fuel supply system, the pre-combustion chamber opens to the cylinder through the first opening and has an ignition element, and the pilot fuel supply system puts the pilot fuel gas into the pre-fuel chamber during the compression stroke. It features a pilot fuel valve configured to inject, allowing the pilot fuel gas to be compressed and mixed with air before it is ignited to form a flammable mixture in the pre-combustion chamber, igniting. The element is configured to ignite the pilot fuel gas in the pre-combustion chamber.

As a result, by using the fuel gas as the pilot fuel, any unwanted emissions generated from the combustion of the fuel oil can be avoided. In addition, the engine can be designed with a smaller fuel supply system, or if the engine is a dual fuel engine, a more reliable engine that can operate on fuel gas alone is provided.

The internal combustion engine is preferably a large low speed turbocharged two-stroke crosshead internal combustion engine with uniflow scavenging for propulsion of marine vessels, with a power of at least 400 kW per cylinder. The internal combustion engine may include a turbocharger driven by the exhaust gas generated by the internal combustion engine and configured to compress the scavenging. An internal combustion engine can be a dual-fuel engine that has an ottocycle mode when powered by fuel gas and has a diesel cycle mode when powered by 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 alternative fuels. During compression, either the air from the cylinder or a mixture of air and fuel gas formed in the cylinder will flow into the prefuel chamber and be mixed with the pilot fuel gas.

The ignition element can be a spark plug, corona / plasma igniter, microwave igniter, glow plug, laser igniter, or jet torch.

The internal combustion engine preferably comprises a plurality of cylinders, for example, between 4 and 14 cylinders. The internal combustion engine further includes a cylinder cover, an exhaust valve, a piston, a fuel gas valve, and a scavenging inlet for each cylinder of the plurality of cylinders.

The fuel gas supply system is preferably configured to inject fuel gas through one or more fuel gas valves under sonic conditions, i.e., at a velocity equal to, i.e., at a constant velocity. .. The sonic state can be achieved when the rate of pressure drop over the nozzle throat (minimum area of cross section) is greater than approximately two.

Correspondingly, the pilot fuel supply system may also be configured to inject pilot fuel gas into the prefuel chamber via the pilot fuel valve under sonic conditions.

One or more fuel gas valves are preferably located on the cylinder wall, at least partially, between top dead center and bottom dead center, above the scavenging inlet. One or more fuel gas valves may include nozzles located on the cylinder wall for injecting fuel gas into the cylinder. In some embodiments, the ignition element is configured to generate an approximately instantaneous maximum energy release at startup.

This may allow further control of ignition timing. Examples of ignition elements capable of producing near-instantaneous energy release at startup are spark plugs, corona / plasma igniters, microwave igniters, laser igniters, or jet torches.

In some embodiments, the one or more fuel gas valves are within 0 to 160 degrees from bottom dead center, within 0 to 130 degrees from bottom dead center, or 0 from bottom dead center. It is configured to inject fuel gas into the cylinder during the compression stroke within 90 degrees to 90 degrees.

Examples of fuel gases are liquefied natural gas (LNG), methane, ethane, and liquefied petroleum gas (LPG).

In some embodiments, the fuel gas supply system and the pilot fuel supply system supply the same fuel gas.

In some embodiments, the engine further comprises a second pre-combustion chamber, the second pre-combustion chamber opens to the cylinder through the second opening and comprises an ignition element, the pilot fuel supply system. A second pilot fuel valve configured to inject the pilot fuel gas into the second pre-combustion chamber during the compression stroke, allowing the pilot fuel gas to be compressed before it is ignited and ignited. The element is configured to ignite the pilot fuel gas in the prefuel chamber.

The two pre-combustion chambers can be the same. The two pre-combustion chambers may be located opposite each other.

The engine may be provided with more pre-combustion chambers, for example at least 3 or 4 pre-combustion chambers per cylinder.

In some embodiments, the pilot fuel valve is within 0 to 160 degrees from bottom dead center, within 0 to 130 degrees from bottom dead center, or 0 to 90 degrees from bottom dead center. Within, it is configured to inject pilot fuel gas into the pre-combustion chamber during the compression stroke.

In some embodiments, the pilot fuel valve is configured to inject pilot fuel gas during the pilot fuel injection period, where the ignition element is located in the prefuel chamber after the end of the pilot fuel injection period. It is configured to ignite the pilot fuel gas.

As a result, suitable mixing with charge air can be achieved by allowing the pilot fuel gas to rest in the pre-fueling chamber before it is ignited. A charge of fuel gas and air from the main chamber of the cylinder can enter the pre-combustion chamber before the ignition element is ignited. This can reduce the amount of pilot fuel gas injected while reaching the flammable mixture as before.

In some embodiments, the pre-fuel chamber has an air-fuel equality ratio of λ of the mixture of scavenging and pilot fuel gas in the pre-fuel chamber at ignition: λ = 1.6, λ = 1.5, λ. It is configured to ensure that it is below = 1.4, or λ = 1.3.

This can be done by controlling the amount of pilot fuel gas injected and by designing the shape of the pre-fuel chamber and the first opening, which allows the desired amount of fuel gas to be pre-produced. Stay in the fuel chamber.

In some embodiments, the ratio between the cross-sectional area of the pre-combustion chamber opening to the cylinder measured at ^{m 2} and the volume of the pre-combustion chamber measured at ^{m 3 is 0.5-1.} It is between .2m- ^1.

As a result, it can be ensured that the pilot fuel gas does not flow out too much from the pre-combustion chamber before it is ignited.

As an example, if the pre-combustion chamber has only the first opening, the surface area of the first opening is 60 mm ² , and the volume of the pre-combustion chamber is 0.1 liter, the ratio is 0. It becomes 6m ^-1.

In some embodiments, the engine is configured to ensure that the λ of the mixture of scavenging and fuel gas in the cylinder is above λ = 2.0.

In some embodiments, the pre-combustion chamber further comprises a second ignition element.

Providing a second ignition element in the pre-combustion chamber provides a more reliable engine, as this engine can operate if one of the ignition elements malfunctions. be.

In some embodiments, the pre-combustion chamber is at least partially located on the cylinder wall and the first opening is formed on the cylinder wall.

In some embodiments, the engine further comprises a pre-combustion chamber cooling system for cooling the pre-combustion chamber, which is close to the pre-combustion chamber for extracting heat from the pre-combustion chamber. A cooling flow path is provided, and the pre-combustion chamber cooling system is configured to circulate a cooling fluid through the cooling flow path.

Placing the pre-combustion chamber on the cylinder wall provides more space for the pre-combustion chamber cooling system. This may allow the temperature of the pre-combustion chamber to be controlled more accurately and with less influence of other engine parameters such as discharge valve closing timing, engine speed, engine load, etc. More precise control of the temperature of the pre-fuel chamber reduces the risk of ignition failure, for example ignition of fuel gases such as liquefied natural gas (LNG), methane, ethane, and liquefied petroleum gas (LPG). It may be more preferred to use pilot fuel, which is difficult.

In some embodiments, the pre-combustion chamber cooling system further comprises a control unit configured to control the flow of the cooling fluid and / or the inlet temperature of the cooling fluid.

In some embodiments, the control unit is of cooling fluid flow and / or cooling fluid depending on engine load, engine speed, and / or air-fuel equality ratio λ of the mixture of scavenging and fuel gas. It is configured to control the inlet temperature.

In some embodiments, the cylinder has a substrate member and a pre-combustion chamber member, the pre-combustion chamber member is located at the top of the substrate member, and the cylinder cover is located at the top of the pre-combustion chamber member. Here, the pre-combustion chamber is at least partially arranged on the cylinder wall of the pre-combustion chamber member, and the pre-combustion chamber is connected to the cylinder through an opening formed in the cylinder wall of the pre-combustion chamber member. It is open.

This allows the pre-combustion chamber member to be specially designed to handle high temperatures and pressures in the pre-combustion chamber, for example by selecting suitable materials. This can also make it easier to perform maintenance on the pre-fuel chamber.

The pre-combustion chamber member may be bolted together with the substrate member of the cylinder. Alternatively, the pre-combustion chamber member can be welded together with the substrate member of the cylinder.

In some embodiments, the pre-combustion chamber member of the cylinder is made of a different material than the substrate member of the cylinder.

In some embodiments, the pre-combustion chamber is at least partially located on the cylinder cover and the first opening is formed on the cylinder cover.

In some embodiments, the engine is a dual fuel engine that has an ottocycle mode when powered by fuel gas and a diesel cycle mode when powered by an alternative fuel, because the engine injects an alternative fuel. Further equipped with a dedicated alternative fuel supply system, the alternative fuel supply system is equipped with one or more fuel injectors located on the cylinder cover, where the engine is one or more when in diesel cycle mode. It is configured to use a fuel injector to inject an alternative fuel at the end of the compression stroke under high pressure, where the engine is for cleaning the pre-fuel chamber when in diesel cycle mode. It is configured to perform the cleaning operation repeatedly.

As a result, the pre-combustion chamber can be protected from combustion by-products generated from the combustion of alternative fuels. This may allow the engine to reliably switch back to Otto cycle mode, even after being in diesel cycle mode for extended periods of time.

The alternative fuel can be heavy oil or marine diesel oil. The engine may be configured to perform a cleaning operation on every engine cycle. Alternatively, the cleaning operation may be performed less frequently, for example, every two engine cycles, every five engine cycles, or once a day. The frequency of cleaning operations can be determined based on engine parameter settings such as engine load and / or sensor data recorded by one or more sensors. The cleaning operation can be performed at any time of the engine cycle.

In some embodiments, the cleaning operation is configured to remove the deposited combustion by-products in the pre-combustion chamber and / or prevent the combustion by-products from accumulating in the pre-combustion chamber.

In some embodiments, the cleaning operation comprises injecting a first fluid using a pilot fuel valve.

In some embodiments, the first fluid is a fuel gas, atmosphere, and / or an inert gas.

In some embodiments, the first fluid is the atmosphere or an inert gas, where the first fluid is used to flush the pre-combustion chamber.

As a result, cleaning the pre-combustion chamber provides a simple method of cleaning the pre-combustion chamber.

Cleaning can be performed when the pressure in the cylinder is low, for example at the beginning of a compression stroke. The injection can be done either before the discharge valve is closed or after the discharge valve is closed.

In some embodiments, the first fluid is the fuel gas, where the ignition element is configured to ignite the fuel gas as part of a cleaning operation.

As a result, unwanted by-products generated from the combustion of alternative fuels in the pre-combustion chamber can be burned off.

In some embodiments, when the engine is in diesel cycle mode, a first type of cleaning operation for cleaning the prefuel chamber with a first frequency and a second type of cleaning operation with a second frequency. Is configured to be repeated, where the second frequency is lower than the first frequency.

In some embodiments, the first type of cleaning operation comprises injecting a first fluid using a pilot fuel valve, where the first fluid is an atmosphere or an inert gas. In, a first fluid is used to clean the pre-combustion chamber, where a second type of cleaning operation comprises using a pilot fuel valve to inject fuel gas, wherein the fuel gas is injected. The ignition element is configured to ignite the fuel gas as part of a second type of cleaning operation.

As a result, the pre-combustion chamber can be effectively kept clean. By injecting fuel gas only as part of the cleaning operation infrequently, the pilot fuel supply system can be purged against the fuel gas most of the time when the engine is in diesel cycle mode, thereby , Improving safety. The second frequency can be less than once an hour, once every 6 hours, once every 12 hours, once a day, once every other day, or once a week.

According to the second aspect, the present invention relates to a prefuel chamber for use with a two-stroke uniflow scavenging crosshead internal combustion engine as described in connection with the first aspect. The pilot fuel gas comprises an ignition element and a pilot fuel valve configured to inject the pilot fuel gas into the prefuel chamber during the compression stroke, which is configured to open into the cylinder through the opening of the. The ignition element is configured to ignite the pilot fuel gas in the pre-combustion chamber, allowing it to be compressed before it is ignited.

Different embodiments of the present invention may be carried out in different ways, including a two-stroke uniflow scavenging crosshead internal combustion engine and pre-combustion chamber as described above and below, to at least one of the embodiments described above. Preferred described in connection with at least one of the embodiments described above and / or disclosed in a dependent claim, each producing one or more of the benefits and benefits described above. Each has one or more preferred embodiments corresponding to the embodiments. Moreover, it will be appreciated that the embodiments described in connection with one of the embodiments described herein may be equally applicable to the other embodiments.

The above and / or additional objectives, features, and advantages of the invention are further clarified by the following exemplary, non-limiting, detailed description of embodiments of the invention with reference to the accompanying drawings. right.

FIG. 1 schematically shows a cross-sectional view of a two-stroke internal combustion engine according to an embodiment of the present invention. FIG. 2 shows a schematic cross-sectional view of a portion of a two-stroke crosshead internal combustion engine with uniflow scavenging according to an embodiment of the present invention. FIG. 3 shows a schematic cross-sectional view of a portion of a two-stroke crosshead internal combustion engine with uniflow scavenging according to an embodiment of the present invention. FIG. 4 shows a schematic view of a pre-combustion chamber according to an embodiment of the present invention. FIG. 5 shows a schematic cross-sectional view of a portion of a two-stroke crosshead internal combustion engine with uniflow scavenging according to an embodiment of the present invention. FIG. 6 shows a schematic view of a pre-combustion chamber according to an embodiment of the present invention.

In the following description, references are made to the accompanying drawings, which show, by way of example, how the present invention can be practiced.

FIG. 1 schematically illustrates a cross-sectional view of a large low speed turbocharged 2-stroke crosshead internal combustion engine 100 with uniflow scavenging for propelling a marine vessel according to an embodiment of the present invention. The engine 100 includes a scavenging system 111, an exhaust gas receiver 108, a fuel gas supply system, and a turbocharger 109. The engine has a plurality of cylinders 101 (only a single cylinder is shown in the cross section). Each cylinder 101 has a cylinder wall 115 and includes a scavenging inlet 102 located at the bottom of the cylinder 101. The engine further comprises a cylinder cover 112 and a piston 103 for each cylinder. The cylinder cover 112 is located at the top of the cylinder 101 and has a discharge valve 104. The piston 103 is movably arranged in the cylinder along the central axis 113 between the bottom dead center and the top dead center. The fuel gas supply system comprises one or more fuel gas valves 105 (shown schematically only) configured to inject fuel gas into the cylinder 101 during the compression stroke, and the fuel gas is evacuated. Allows mixing with and allows the mixture of scavenger and fuel gas to be compressed before being ignited. The engine further comprises a pre-combustion chamber 114 and a pilot fuel supply system, which opens into the cylinder 101 through a first opening and includes an ignition element (not shown). The pilot fuel supply system is equipped with a pilot fuel valve (not shown) configured to inject the pilot fuel gas into the prefuel chamber during the compression stroke so that the pilot fuel gas is compressed before it is ignited. The ignition element is configured to ignite the pilot fuel gas in the pre-combustion chamber, enabling it. The pre-combustion chamber 114 is located on the cylinder wall 115 in this embodiment, however, in other embodiments the pre-combustion chamber 114 may be located on the cylinder cover 112. The scavenging inlet 102 is fluidly connected to the scavenging system. Piston 103 is shown at its lowest position (bottom dead center). The piston 103 has a piston rod connected to a crankshaft (not shown). The fuel gas valve 105 is configured to inject fuel gas into the cylinder during the compression stroke, allowing the fuel gas to mix with the scavenger and compressing the mixture of scavenging and fuel gas before it is ignited. Allow to be done. The fuel gas valve 105 is located at least partially on the cylinder wall between the cylinder cover 112 and the scavenging inlet 102, for example, the fuel gas nozzle of the fuel gas valve 105 may be located on the cylinder wall and the fuel gas. The rest of the valve can be located outside the cylinder. The fuel gas valve is at the beginning of the compression stroke within 0 to 130 degrees from bottom dead center, that is, when the crankshaft rotates between 0 and 130 degrees from its orientation at bottom dead center. It is configured to inject fuel gas into the cylinder 101. Preferably, the fuel gas valve 105 has the crankshaft shaft rotated several degrees from bottom dead center so that the piston passes through the scavenging inlet 102 to prevent the fuel gas from flowing out through the scavenging inlet 102. Later, it is configured to start injecting fuel gas. The scavenging system 111 includes a scavenging receiver 110 and an air cooler 106.

The engine 100 is preferably a dual fuel engine having an Otto cycle mode when powered by fuel gas and a diesel cycle mode when powered by alternative fuels such as heavy oil or marine diesel oil. Such a dual fuel engine has its own dedicated alternative fuel supply system for injecting alternative fuels. Thus, optionally, the engine 100 further comprises one or more fuel injectors 116 located on a cylinder cover 112 that forms part of an alternative fuel supply system. When the engine 100 is powered by an alternative fuel, the fuel injector 116 is configured to inject an alternative fuel, eg, heavy oil, at the end of the compression stroke under high pressure.

FIG. 2 shows a schematic cross-sectional view of a portion of a two-stroke crosshead internal combustion engine with uniflow scavenging according to an embodiment of the present invention. A cylinder 101, a cylinder cover 112, a piston 103, and a discharge valve 104 are shown. The piston 103 is located at top dead center. The cylinder 101 has a cylinder wall 115 provided with a first pre-combustion chamber 114 and a second pre-combustion chamber 116. The first and second pre-combustion chambers 114 and 116 open to the cylinder 101 through an opening formed in the cylinder wall 115, and the pre-combustion chambers 114 and 116 collect a mixture of scavenging air in the cylinder and fuel gas. It is configured to ignite. The engine further comprises a pilot fuel supply system with a first pilot fuel valve located in the first pre-fueling chamber 114 and a second pilot fuel valve located in the second pre-fueling chamber 116. The first and second pilot fuel valves are configured to inject pilot fuel gas into the prefuel chamber. The first and second pre-combustion chambers 114, 116 further include an ignition element configured to ignite the pilot fuel gas.

FIG. 3 shows a schematic cross-sectional view of a portion of a two-stroke crosshead internal combustion engine with uniflow scavenging according to an embodiment of the present invention. This portion corresponds to the portion shown in FIG. 2, with the difference that the cylinder 101 has a substrate member 117 and a pre-combustion chamber member 118, with the pre-combustion chamber member 118 located at the top of the substrate member 117. The cylinder cover 112 is located at the top of the pre-combustion chamber member 118. The first and second pre-combustion chambers 114 and 116 are arranged on the cylinder wall of the pre-combustion chamber member 118. This allows the pre-combustion chamber members to be specially designed to handle high temperatures and pressures in the pre-combustion chamber, for example by selecting suitable materials.

FIG. 4 shows a schematic view of the pre-combustion chamber 114 according to the embodiment of the present invention. The pre-combustion chamber 114 is configured to open to the cylinder through the first opening 123 and the second opening 124. The pre-combustion chamber includes an ignition element 119 and a pilot fuel valve 120 configured to inject pilot fuel gas into the pre-fuel chamber during the compression stroke and is compressed before the pilot fuel gas 121 is ignited. Make it possible. The ignition element 119 is configured to ignite the pilot fuel gas in the prefuel chamber, providing a torch 122 for igniting the fuel gas in the cylinder.

FIG. 5 shows a schematic cross-sectional view of a portion of a two-stroke crosshead internal combustion engine with uniflow scavenging according to an embodiment of the present invention. A cylinder 101, a cylinder cover 112, and a discharge valve 104 are shown. The cylinder cover 112 is provided with a first pre-combustion chamber 114 and a second pre-combustion chamber 116. The first and second pre-combustion chambers 114 and 116 open to the cylinder 101 through an opening formed in the cylinder cover 112, and the pre-combustion chambers 114 and 116 collect a mixture of scavenging air in the cylinder and fuel gas. It is configured to ignite. The engine further comprises a pilot fuel supply system with a first pilot fuel valve located in the first pre-fueling chamber 114 and a second pilot fuel valve located in the second pre-fueling chamber 116. The first and second pilot fuel valves are configured to inject pilot fuel gas into the prefuel chamber. The first and second pre-combustion chambers 114, 116 further include an ignition element configured to ignite the pilot fuel gas.

FIG. 6 shows a schematic view of the pre-combustion chamber 114 according to the embodiment of the present invention. The pre-combustion chamber 114 is configured to open to the cylinder through the first opening 123 and the second opening 124. The pre-combustion chamber includes an ignition element 119 and a pilot fuel valve 120 configured to inject pilot fuel gas into the pre-fuel chamber during the compression stroke and is compressed before the pilot fuel gas 121 is ignited. Make it possible. The ignition element 119 is configured to ignite the pilot fuel gas in the prefuel chamber, providing a torch 122 for igniting the fuel gas in the cylinder. In this embodiment, the engine is configured to repeatedly perform a cleaning operation to clean the pre-fuel chamber 114 when in diesel cycle mode (and therefore not using the pre-fuel chamber 114). In this embodiment, the pilot fuel valve 120 is fluidly connected to both the gas tank 140 and the N2 tank 130. The pilot fuel valve 120 is fluidly connected to the gas tank 140 via a compressor 141 and a shutoff valve 142 configured to pressurize the gas. Correspondingly, the pilot fuel valve 120 is fluidly connected to the N2 tank 130 via a compressor 131 and a shutoff valve 132 configured to pressurize the N2. The N2 supply system 130 131 132 also also includes one or more blowout tubes (not shown) when the gas supply system is not in use, for example when the engine is in diesel cycle mode. Can be used to purge the gas supply system 140 141 142. The cleaning operation may be configured to remove the combustion by-products deposited in the pre-combustion chamber and / or prevent the combustion by-products from accumulating in the pre-combustion chamber. The cleaning operation may include injection of a first fluid using the pilot fuel valve 120. The first fluid can be N2 supplied from the N2 tank 130, where the first fluid is used to clean the pre-combustion chamber 114. Alternatively / additionally, the first fluid may be the fuel gas supplied from the gas tank 140, where the ignition element 119 is configured to ignite the fuel gas as part of a cleaning operation. By this, unwanted combustion by-products can be burned off.

Although some embodiments have been described and shown in detail, the invention is not limited to them and is also embodied in other ways within the scope of the claims set forth below. obtain. In particular, it should be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the invention.

In a device claim that lists several means, some of these means may be embodied by one and the same item of hardware. The mere fact that certain measures are described in different dependent claims or described in different embodiments does not indicate that a combination of these measures cannot be used in an advantageous manner. do not have.

As used herein, the term "comprises / complementing" identifies the presence of a described feature, integer, step, or component, but one or more other features, integers, steps. It should be emphasized that it does not preclude the existence or addition of, components, or groups thereof.
The inventions described in the claims at the time of filing the application of the present application are described below.
[1] A two-stroke uniflow scavenging crosshead internal combustion engine (100) including at least one cylinder (101), a cylinder cover (112), a piston (103), a fuel gas supply system, and a scavenging system (111). The cylinder has a cylinder wall (115), the cylinder cover is located at the top of the cylinder and has a discharge valve (104), and the piston has a bottom dead point and a top dead point. Movably disposed in the cylinder along the central axis (113) with and from, the scavenging system (111) has a scavenging inlet (102) located at the bottom of the cylinder and the fuel. The gas supply system comprises a fuel gas valve (105) that is at least partially located on the cylinder wall and configured to inject fuel gas into the cylinder during a compression stroke, the fuel gas being mixed with scavenging air. Allows the mixture of scavenging and fuel gas to be compressed before being ignited, where the engine further comprises a pre-combustion chamber (114) and a pilot fuel supply system. In an internal combustion engine, the pre-combustion chamber (114) opens into the cylinder through a first opening (123) and comprises an ignition element (119), the pilot fuel supply system during the compression stroke. A pilot fuel valve (120) configured to inject the pilot fuel gas (121) into the prefuel chamber is provided to allow the pilot fuel gas to be compressed before being ignited, the ignition element (12). A two-stroke uniflow scavenging cross-head internal combustion engine, characterized in that the 119) is configured to ignite the pilot fuel gas (121) in the prefueling chamber (114).
[2] The two-stroke crosshead internal combustion engine according to [1], wherein the fuel gas supply system and the pilot fuel supply system supply the same fuel gas.
[3] The pilot fuel valve (120) is within 0 to 160 degrees from bottom dead center, within 0 to 130 degrees from bottom dead center, or from 0 to 90 degrees from bottom dead center. The two-stroke crosshead internal combustion engine according to [1] or [2], which is configured to inject the pilot fuel gas (121) into the prefuel chamber (114) during the compression stroke.
[4] The pilot fuel valve (120) is configured to inject the pilot fuel gas (121) during the pilot fuel injection period, and the ignition element (119) ends the pilot fuel injection period. The two-stroke crosshead internal combustion engine according to [3], which is configured to later ignite the pilot fuel gas (121) in the prefuel chamber (114).
[5] In the pre-fuel chamber (114), the air-fuel equal amount ratio λ of the mixture of the scavenging air in the pre-fuel chamber (114) and the pilot fuel gas (121) is λ = 1.6 at the time of ignition. The two-stroke crosshead internal combustion engine according to [4], which is configured to ensure lowering.
[6] The cross-sectional area of the openings (123, 124) of the pre-combustion chamber (114) to the cylinder (101) measured at ^{m 2} and the volume of the pre-combustion chamber measured at ^{m 3.} The two-stroke crosshead internal combustion engine according to [5] , wherein the ratio between the ^{two strokes is between 0.5 and 1.2 m -1.}
[7] The engine according to [6], wherein the engine is configured to ensure that the λ of the mixture of the scavenging air in the cylinder and the fuel gas exceeds λ = 2.0. Stroke crosshead internal combustion engine.
[8] The pre-combustion chamber (114) is at least partially arranged in the cylinder wall (115), and the first opening (123) is formed in the cylinder wall [1]. ] To [7], the two-stroke crosshead internal combustion engine according to any one of the items.
[9] The pre-combustion chamber (114) is at least partially arranged in the cylinder cover (112), and the first opening (123) is formed in the cylinder cover (112). , The 2-stroke crosshead internal combustion engine according to any one of [1] to [8].
[10] The two-stroke crosshead according to any one of [1] to [9], wherein the ignition element (119) is configured to generate a substantially instantaneous maximum energy release at startup. Internal combustion engine.
[11] The engine is a dual fuel engine having an ottocycle mode when operating on fuel gas and a diesel cycle mode when operating on an alternative fuel, wherein the engine is for injecting the alternative fuel. Further comprising a dedicated alternative fuel supply system, the alternative fuel supply system comprises one or more fuel injectors located on the cylinder cover, the engine having one or more when in the diesel cycle mode. The fuel injector is configured to inject the alternative fuel at the end of the compression stroke under high pressure, and the engine cleans the prefuel chamber when in the diesel cycle mode. The two-stroke crosshead internal combustion engine according to any one of [1] to [9], which is configured to repeatedly perform a cleaning operation for performing the cleaning operation.
[12] The cleaning operation is configured to remove combustion by-products accumulated in the pre-combustion chamber and / or prevent combustion by-products from accumulating in the pre-combustion chamber, [11]. The two-stroke crosshead internal combustion engine described.
[13] The two-stroke crosshead internal combustion engine according to [11] or [12], wherein the cleaning operation comprises injecting a first fluid using the pilot fuel valve.
[14] The two-stroke crosshead internal combustion engine according to [12], wherein the first fluid is a fuel gas, an atmosphere, and / or an inert gas.
[15] The two-stroke crosshead internal combustion engine according to [14], wherein the first fluid is the atmosphere or an inert gas, and the first fluid is used for cleaning the prefuel chamber. ..
[16] The two-stroke crosshead according to [13], wherein the first fluid is a fuel gas and the ignition element is configured to ignite the fuel gas as part of the cleaning operation. Internal combustion engine.
[17] When the engine is in the diesel cycle mode, the engine performs a first type cleaning operation for cleaning the prefuel chamber with a first frequency and a second type cleaning operation with a second frequency. The two-stroke crosshead internal combustion engine according to any one of [11] to [16], which is configured to be repeatedly executed and whose second frequency is lower than that of the first frequency.
[18] The first type of cleaning operation comprises injecting a first fluid using the pilot fuel valve, wherein the first fluid is an atmosphere or an inert gas, said first. The fluid of 1 is used to clean the pre-combustion chamber, the second type of cleaning operation comprises using the pilot fuel valve to inject fuel gas, and the ignition element is said to be said. The two-stroke crosshead internal combustion engine according to [17], which is configured to ignite the fuel gas as part of a second type of cleaning operation.
[19] A prefueling chamber for use with the two-stroke uniflow scavenging crosshead internal combustion engine according to any one of [1] to [10], wherein the prefueling chamber (114) is the first. In a pre-combustion chamber configured to open through an opening (123) to a cylinder (101) and comprising an ignition element (119), the pre-combustion chamber provides pilot fuel gas (121) during the compression stroke. A pilot fuel valve (120) configured to inject into the pre-fuel chamber (114) is further provided to allow the pilot fuel gas (121) to be compressed before being ignited and the ignition element (120). The pre-combustion chamber is characterized in that the 119) is configured to ignite the pilot fuel gas (121) in the pre-fuel chamber (114).

Claims (10)

A two-stroke uniflow scavenging crosshead internal combustion engine (100) comprising at least one cylinder (101), a cylinder cover (112), a piston (103), a fuel gas supply system, and a scavenging system (111). The cylinder has a cylinder wall (115), the cylinder cover is located at the top of the cylinder and has a discharge valve (104), and the piston is between the bottom dead point and the top dead point. Movably disposed in the cylinder along the central axis (113), the scavenging system (111) has a scavenging inlet (102) located at the bottom of the cylinder and the fuel gas supply system. Provided a fuel gas valve (105) that is at least partially disposed on the cylinder wall and configured to inject fuel gas into the cylinder during a compression stroke so that the fuel gas mixes with the scavenger. It allows the mixture of scavenging air and fuel gas to be compressed before it is ignited, where the engine further comprises a pre-combustion chamber (114) and a pilot fuel supply system. In an internal combustion engine, where the fuel chamber (114) opens into the cylinder through a first opening (123) and comprises an ignition element (119), the pilot fuel supply system allows the pilot fuel gas during the compression stroke. A pilot fuel valve (120) configured to inject (121) into the prefuel chamber is provided to allow the pilot fuel gas to be compressed before it is ignited so that the ignition element (119) , The pilot fuel gas (121) in the pre-fuel chamber (114) is configured to ignite, where the pilot fuel valve (120) is within 0 to 160 degrees from the bottom dead point. Within 0 to 130 degrees from the bottom dead point, or within 0 to 90 degrees from the bottom dead point, the pilot fuel gas (121) is injected into the prefuel chamber (114) during the compression stroke. A two-stroke uniflow scavenging cross-head internal combustion engine, characterized in that it is configured to. The two-stroke uniflow scavenging crosshead internal combustion engine according to claim 1, wherein the fuel gas supply system and the pilot fuel supply system supply the same fuel gas. The pilot fuel valve (120) is configured to inject the pilot fuel gas (121) during the pilot fuel injection period, and the ignition element (119) is said after the end of the pilot fuel injection period. The two-stroke uniflow scavenging crosshead internal combustion engine according to claim 1, which is configured to ignite the pilot fuel gas (121) in the prefuel chamber (114). In the pre-fuel chamber (114), the air-fuel equal amount ratio λ of the mixture of the scavenging air in the pre-fuel chamber (114) and the pilot fuel gas (121) becomes lower than λ = 1.6 at the time of ignition. The two-stroke uniflow scavenging crosshead internal combustion engine according to claim 3, which is configured to ensure that The ratio between the cross-sectional area of the openings (123, 124) of the pre-combustion chamber (114) to the cylinder (101) measured at m ² and the volume of the pre-fuel chamber measured at ^{m 3.} Is a two-stroke uniflow scavenging crosshead internal combustion engine according to claim 4, wherein is between 0.5 and 1.2 m- ^1. The two-stroke uniflow scavenging according to claim 5, wherein the engine is configured to ensure that the λ of the mixture of the scavenging in the cylinder and the fuel gas exceeds λ = 2.0. Crosshead internal combustion engine. Claims 1 to 6, wherein the pre-combustion chamber (114) is at least partially arranged in the cylinder wall (115), and the first opening (123) is formed in the cylinder wall. The two-stroke uniflow scavenging crosshead internal combustion engine according to any one of the above. The prefueling chamber (114) is at least partially arranged in the cylinder cover (112), and the first opening (123) is formed in the cylinder cover (112). The 2-stroke uniflow scavenging crosshead internal combustion engine according to any one of 1 to 7. The two-stroke uniflow scavenging crosshead internal combustion engine according to any one of claims 1 to 8, wherein the ignition element (119) is configured to generate an instantaneous maximum energy release at startup. A prefueling chamber for use with the two-stroke uniflow scavenging crosshead internal combustion engine according to any one of claims 1 to 9, wherein the prefueling chamber (114) is a first opening (123). In a pre-combustion chamber configured to open through to a cylinder (101) and comprising an ignition element (119), the pre-combustion chamber transfers pilot fuel gas (121) to the pre-combustion chamber (121) during the compression stroke. A pilot fuel valve (120) configured to inject into 114) is further provided to allow the pilot fuel gas (121) to be compressed before being ignited, the ignition element (119) being said. It is configured to ignite the pilot fuel gas (121) in the pre-fuel chamber (114), where the pilot fuel valve (120) dies within 0 to 160 degrees from bottom dead center. The pilot fuel gas (121) is injected into the pre-combustion chamber (114) during the compression stroke within 0 to 130 degrees from the point or within 0 to 90 degrees from bottom dead center. A pre-fueling chamber characterized by being configured in.

Images