KR20210156789A - Internal combustion engine - Google Patents

Abstract

A two-stroke uniflow scavenging crosshead internal combustion engine is disclosed. The two-stroke uniflow scavenging crosshead internal combustion engine includes at least one cylinder, a cylinder cover, a piston, a fuel gas supply system, and a scavenging system. The engine further includes a pilot pre-chamber unit including at least one pre-chamber, a pilot fuel valve housing, and a pilot fuel valve disposed in the pilot fuel valve housing. The at least one pre-chamber has a pre-chamber wall and opens into the cylinder through a first opening, and the pilot pre-chamber unit is configured to ignite a mixture of scavenging gas and fuel gas in the cylinder. The pilot pre-chamber unit further comprises a first heat exchange channel for circulating a heat exchange fluid, wherein the first heat exchange channel has an inlet and an outlet. The inlet and the outlet are both arranged in the pilot fuel valve housing. According to the present invention, effective temperature control and easy maintenance are provided.

Description

internal combustion engine {INTERNAL COMBUSTION ENGINE}

FIELD OF THE INVENTION The present invention relates to a two-stroke uniflow scavenging crosshead internal combustion engine and a pilot pre-chamber unit for a two-stroke uniflow scavenging crosshead internal combustion engine.

Two-stroke internal combustion engines are used as propulsion engines in ships such as container ships, bulk carriers, and oil tankers. It is becoming increasingly important to reduce unwanted exhaust gases from internal combustion engines.

One effective way to reduce the amount of unwanted exhaust gases is, for example, conversion from heavy fuel oil (HFO) to fuel gas. The fuel gas may be injected into the cylinder at the end of the compression stroke, where it may be ignited immediately by the high temperature the gas in the cylinder reaches during compression or by ignition of the pilot fuel. However, injecting fuel gas into the cylinder at the end of the compression stroke requires a high pressure compressor to compress the fuel gas prior to injection so that the high pressure in the cylinder can be overcome.

However, high pressure compressors are expensive and complex to manufacture and maintain. One way to avoid the use of a high pressure compressor is to configure the engine to inject fuel gas at the beginning of the compression stroke where the pressure in the cylinder is significantly lower.

Patent document WO 2013/007863 discloses such an engine. A pilot ignition pre-chamber is provided in the cylinder cover to ensure proper ignition of the fuel gas. A predetermined amount of pilot fuel oil is injected into the pilot ignition pre-chamber, which is then self-ignited due to the temperature and pressure in the pilot ignition pre-chamber. This causes a spark that ignites the fuel gas in the main chamber of the cylinder.

However, it is difficult to ensure adequate cooling of the pre-chamber. Also, preventing leakage of cooling fluid and making maintenance easier can be a challenge.

Accordingly, there remains a problem to provide an improved method of cooling the pre-chamber.

According to a first aspect, the present invention relates to a two-stroke uniflow scavenge crosshead internal combustion engine comprising at least one cylinder, a cylinder cover, a piston, a fuel gas supply system, and a scavenging air system, the cylinder comprising: a cylinder wall, wherein the cylinder cover is arranged on top of the cylinder and has an exhaust valve, wherein the piston is arranged movably within the cylinder along a central axis between bottom dead center and top dead center; having a scavenging air inlet arranged at the bottom of the cylinder, the fuel gas supply system being at least partially arranged in the cylinder wall and configured to inject fuel gas into the cylinder during a compression stroke such that the fuel gas is mixed with the scavenging air and a fuel gas valve allowing the mixture of scavenge air and fuel gas to be compressed prior to ignition;

The engine further comprises a pilot pre-chamber unit comprising at least one pre-chamber, a pilot fuel valve housing, and a pilot fuel valve arranged within the pilot fuel valve housing, wherein the at least one pre-chamber is a first for circulating a heat exchange fluid having an inlet and an outlet, the pilot pre-chamber unit having a chamber wall, the pilot pre-chamber unit being configured to ignite a mixture of fuel gas and scavenging air in the cylinder, the pilot pre-chamber unit having an inlet and an outlet and a heat exchange channel, wherein both said inlet and said outlet are arranged in said pilot fuel valve housing.

Accordingly, both effective temperature control and easy maintenance are provided by providing the pilot pre-chamber with the heat exchange channels arranged in the pilot fuel valve housing at both the inlet and outlet.

Preferably the internal combustion engine is a uniflow scavenging, large, low-speed turbocharged, two-stroke crosshead internal combustion engine for propulsion of marine vessels with a power of at least 400 kW per cylinder. The internal combustion engine may include a turbocharger that is driven by exhaust gases generated by the internal combustion engine and is configured to compress scavenging air. The internal combustion engine may be a dual-fuel engine having an auto cycle mode driven by fuel gas and a diesel cycle mode driven by an alternative fuel such as heavy oil or marine diesel oil. Such dual-fuel engines have a dedicated fuel supply system for injecting alternative fuels.

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

Preferably, the fuel gas supply system is configured to inject fuel gas via one or more fuel gas valves under sonic conditions, ie a speed equal to the speed of sound, ie a constant velocity. The sonic condition can be achieved when the pressure drop ratio in the nozzle throat (minimum cross-sectional area) is greater than approximately two.

In some embodiments, the one or more fuel gas valves direct fuel gas into the cylinder during a compression stroke between 0 degrees and 160 degrees from bottom dead center, or between 0 degrees and 130 degrees from bottom dead center, or between 0 degrees and 90 degrees from bottom dead center. is configured to spray.

The one or more fuel gas valves are arranged at least partially in the cylinder wall between top dead center and bottom dead center, preferably above the scavenging air inlet. The one or more fuel gas valves may include a nozzle arranged in the cylinder wall for injecting fuel gas into the cylinder. Another part of the fuel gas valve (parts other than the nozzle) may be arranged outside the cylinder wall.

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

The pilot fuel valve is configured to inject pilot fuel into the at least one pre-chamber. The at least one pre-chamber may be configured such that the pilot fuel self-ignites due to the temperature and pressure within the at least one pre-chamber. Alternatively, the pilot fuel in the at least one pre-chamber may be ignited by means comprising a spark plug or a laser igniter. The pilot fuel may be heavy oil or marine diesel oil, or another suitable ignitable fuel, precisely measured to ignite the mixture of fuel gas and scavenging air in the cylinder. A pilot fuel system may be much smaller in size and more suitable for injecting the correct amount of pilot fuel than a dedicated fuel supply system for an alternative fuel, and a dedicated fuel supply system for an alternative fuel may be larger Due to the size of the components it may not be suitable for this purpose. The pilot fuel supply system may be configured to inject a predetermined amount of pilot oil at an appropriate crank angle for optimal ignition of the main charge, near top dead center. Pilot fuel ignition immediately follows pilot oil injection, and main charge ignition immediately follows pilot oil ignition.

The pilot pre-chamber unit may be arranged in the cylinder wall or in the cylinder cover. At least a portion of the pilot pre-chamber unit may extend outside the portion of the engine into which the pilot pre-chamber unit is inserted, for example at least a portion of the pilot pre-chamber unit may extend outside the cylinder wall or cylinder cover . Both the inlet and outlet of the first heat exchange channel may be arranged in a portion of the pilot pre-chamber unit extending out of the portion of the engine into which the pilot pre-chamber unit is inserted. The pilot pre-chamber unit may be removably connected to the portion of the engine into which the pilot pre-chamber unit is inserted, allowing removal of the pilot pre-chamber unit for maintenance purposes.

The first heat exchange channel may be part of a pre-chamber cooling system configured to cool the at least one pre-chamber, eg, the pre-chamber cooling system cools the heat exchange fluid prior to providing the heat exchange fluid to the first thermostatic channel. can be configured to

The pre-chamber cooling system may include a control unit configured to control a flow of the heat exchange fluid and/or an inlet temperature of the heat exchange fluid. The control unit may be configured to control the flow of the heat exchange fluid and/or the inlet temperature of the heat exchange fluid depending on the engine load, the engine speed, and/or the air-fuel equivalence ratio λ of the mixture of scavenge air and fuel gas.

Alternatively, the heat exchange channel may be part of a combined heating and cooling system configured to cool or heat the at least one pre-chamber, for example the combined heating and cooling system may be configured to provide a heat exchange fluid to the first temperature control channel. It may be configured to cool or heat the heat exchange fluid before. The combined heating and cooling system may be configured to heat the at least one pre-chamber when converting heavy oil or marine diesel oil to fuel gas or as part of a gas start procedure from a complete engine shutdown. The combined heating and cooling system is designed to prevent damage to the at least one pre-chamber and/or surrounding engine components after the gas start-up procedure has been completed, ie during normal gas operation, in the at least one pre-chamber. may be configured to cool the

Examples of heat exchange fluids include water, air and system oils.

In some embodiments, the first heat exchange channel extends inside both a portion of the pre-chamber wall and a portion of the pilot fuel valve housing.

Thus, by having the first heat exchange channel arranged directly in the interior of the pre-chamber wall, the temperature of the at least one pre-chamber can be adjusted effectively and accurately.

A portion of the first heat exchange channel extending inside the pre-chamber may be formed at the same time the at least one pre-chamber is formed, for example using additive manufacturing techniques. A portion of the first heat exchange channel extending inside the pre-chamber wall and a portion extending inside the pilot fuel valve housing may be formed in two separate processes and then connected. Alternatively, the portion of the first heat exchange channel extending inside the pre-chamber wall and the portion extending inside the pilot fuel valve housing may be formed in a single process using, for example, additive manufacturing.

In some embodiments, the at least one pre-chamber and pilot fuel valve housing are two separate elements connected together.

The at least one pre-chamber and pilot fuel valve housing may be connected using any suitable connection method, for example using bolted connections or welding. The at least one pre-chamber and pilot valve housing may be releasably connected or non-separably connected.

In some embodiments, the at least one pre-chamber and pilot fuel valve housing are formed as one element produced in a single process.

The at least one pre-chamber and pilot fuel valve housing may be cast together in a single casting process or formed as one element using additive manufacturing.

In some embodiments, the at least one pre-chamber comprises a first opening opening into the cylinder, and the first heat exchange channel is a first portion for guiding the heat exchange fluid towards the first opening of the at least one pre-chamber. and a second portion for guiding the heat exchange fluid away from the first opening of the at least one pre-chamber, wherein a shape of the first portion substantially corresponds to a shape of the second portion.

Accordingly, more uniform temperature control of the pilot pre-chamber unit can be achieved. This can ensure more effective temperature control and can prevent tension in the pilot pre-chamber unit.

In some embodiments, the pilot pre-chamber unit further comprises a second heat exchange channel for circulating a heat exchange fluid having an inlet and an outlet and extending through the pilot fuel valve housing and the pre-chamber wall, the inlet and Both outlets are arranged within the pilot fuel valve housing.

Accordingly, by having multiple temperature control channels, more uniform temperature control can be achieved. This can further reduce the flow rate required for the heat exchange fluid, which in turn allows the temperature control channel to have a smaller diameter and can therefore be arranged much closer to the pre-chamber allowing more accurate temperature control. do.

The second heat exchange channel has a first portion for directing the heat exchange fluid towards the first opening of the at least one pre-chamber and a second portion for conducting the heat exchange fluid away from the first opening of the at least one pre-chamber. wherein the shape of the first portion substantially corresponds to the shape of the second portion.

In some embodiments, the pilot pre-chamber unit further comprises a third heat exchange channel for circulating a heat exchange fluid having an inlet and an outlet and extending through the pilot fuel valve housing and the pre-chamber wall, wherein the inlet and Both outlets are arranged within the pilot fuel valve housing.

The third heat exchange channel has a first portion for directing the heat exchange fluid towards the first opening of the at least one pre-chamber and a second portion for conducting the heat exchange fluid away from the first opening of the at least one pre-chamber. wherein the shape of the first portion substantially corresponds to the shape of the second portion.

In some embodiments, the first, second and third heat exchange channels are arranged rotationally symmetrically.

In some embodiments, the engine further comprises a pre-chamber housing, wherein the at least one pre-chamber is arranged within the pre-chamber housing, the at least one pre-chamber supporting the pre-chamber housing and the pre-chamber housing at least a first contact and a second contact for securing the at least one pre-chamber therein, wherein the pre-chamber housing has a first contact and a second contact to limit heat exchange between the at least one pre-chamber and the engine. It has a first insulating space formed therebetween.

Accordingly, by insulating the at least one pre-chamber from the part of the engine in which the at least one pre-chamber is inserted, the temperature of the at least one pre-chamber can be controlled more precisely. This may also allow the portion of the engine adjacent the at least one pre-chamber to be made of a material having a lower heat resistance, such as cast iron.

Accordingly, by insulating the pre-chamber from the part of the engine into which the pre-chamber is inserted, the temperature of the pre-chamber can be controlled more precisely. This may also allow the part of the engine adjacent the pre-chamber to be made of a material with low heat resistance, such as cast iron.

In some embodiments, the at least one pre-chamber further has a third contact for supporting the pre-chamber housing, wherein the pre-chamber housing defines a second insulating space formed between the second contact and the third contact. have more

In some embodiments, the at least one pre-chamber and the temperature control channel are fabricated in a single additive manufacturing process.

In some embodiments, the at least one cylinder has a base member and a pre-chamber member, wherein the pre-chamber member is arranged on top of the base member and the cylinder cover is arranged on top of the pre-chamber member, wherein the pilot pre-chamber member The chamber unit is arranged at least partially in a cylinder wall of the pre-chamber member, the first opening opening into the cylinder through an opening formed in the cylinder wall of the pre-chamber member.

This allows the pre-chamber member to be specially designed to handle the high temperatures and high pressures in the pre-chamber, for example by selecting the appropriate material. This makes it easier to perform maintenance on the pre-chamber. The pre-chamber member may be inserted between the base member and the cylinder cover, and may or may not have a gasket arranged toward either side. It can be pre-assembled with the base member before the cylinder cover is installed.

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

The base member of the cylinder may be made of cast iron and the pre-chamber member may be made of steel.

In some embodiments, the pre-chamber is connected to the first opening via a channel extending along a first axis, wherein the angle between the first axis and a reference plane arranged perpendicular to the central axis is: 0 degrees to 85 degrees, 0 degrees to 80 degrees, 0 degrees to 60 degrees, 0 degrees to 45 degrees, or 0 degrees to 30 degrees.

The flame extending from the pre-chamber into the cylinder is thus able to come into direct contact with a large portion of the mixture of scavenging air and fuel gas.

The engine may have a greater number of pre-chambers per cylinder, such as at least two, three or four pre-chambers.

According to a second aspect, the present invention relates to a pilot pre-chamber unit for a two-stroke uniflow scavenge crosshead internal combustion engine comprising at least one cylinder as disclosed in connection with the second aspect of the present invention, the pilot pre-chamber unit comprising: wherein the pilot pre-chamber unit comprises at least one pre-chamber, a pilot fuel valve housing, and a pilot fuel valve arranged within the pilot fuel valve housing, the at least one pre-chamber having a pre-chamber wall, the the pilot pre-chamber unit is configured to ignite a mixture of scavenge air and fuel gas within the cylinder, the pilot pre-chamber unit further comprising a first heat exchange channel for circulating a heat exchange fluid having an inlet and an outlet; Both the inlet and the outlet are arranged in the pilot fuel valve housing.

Different aspects of the present invention may be implemented in different ways, including a two-stroke uniflow scavenge crosshead internal combustion engine and a pilot pre-chamber unit, each as described above and as described below, in different ways. yields one or more advantages and advantages described in connection with at least one of the aspects, each corresponding to a preferred embodiment described in connection with at least one of the aspects described above and/or disclosed in the dependent claims have an embodiment. Furthermore, it will be understood that an embodiment described in connection with one of the aspects described herein may be equally applicable to another aspect.

There are always two angles between two axes, two planes or one axis and one plane, a small angle V1 and a large angle V2, where V2 = 180 degrees - V1 . In the present disclosure, what is described is always a small angle V1.

According to the present invention, both effective temperature control and easy maintenance are provided by providing a pilot pre-chamber having heat exchange channels arranged in the pilot fuel valve housing at both the inlet and outlet.

According to the invention, by having the first heat exchange channel arranged directly in the interior of the pre-chamber wall, the temperature of the at least one pre-chamber can be adjusted effectively and accurately.

According to the present invention, by having multiple temperature control channels, more uniform temperature control can be achieved. This can further reduce the flow rate required for the heat exchange fluid, which in turn allows the temperature control channel to have a smaller diameter and can therefore be arranged much closer to the pre-chamber allowing more accurate temperature control. do.

According to the present invention, by insulating the at least one pre-chamber from the part of the engine in which the at least one pre-chamber is inserted, the temperature of the at least one pre-chamber can be controlled more precisely. This may also allow the portion of the engine adjacent the at least one pre-chamber to be made of a material having a lower heat resistance, such as cast iron.

According to the present invention, by insulating the pre-chamber from the part of the engine in which the pre-chamber is inserted, the temperature of the pre-chamber can be controlled more precisely. This may also allow the part of the engine adjacent the pre-chamber to be made of a material with low heat resistance, such as cast iron.

According to the present invention, the flame extending from the pre-chamber into the cylinder can be in direct contact with a large portion of the mixture of scavenging air and fuel gas.

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.
1 is a schematic cross-sectional view of a two-stroke internal combustion engine according to an embodiment of the present invention;
2 is a partial schematic cross-sectional view of a uniflow scavenging two-stroke crosshead internal combustion engine according to an embodiment of the present invention.
3 is a partial schematic cross-sectional view of a uniflow scavenging two-stroke crosshead internal combustion engine according to an embodiment of the present invention.
4 is a partial schematic cross-sectional view of a uniflow scavenging two-stroke crosshead internal combustion engine according to an embodiment of the present invention.
5 is a schematic diagram of a pilot pre-chamber unit 114 for a two-stroke uniflow scavenging crosshead internal combustion engine in accordance with an embodiment of the present invention.
6 shows a schematic diagram of a pilot pre-chamber unit 114 for a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the present invention.
7A and 7B are cross-sectional views of a uniflow scavenging large-scale, low-speed turbocharged two-stroke crosshead internal combustion engine for propulsion of a marine vessel according to an embodiment of the present invention.

DETAILED DESCRIPTION In the following description, reference is made to the accompanying drawings, which show by way of example how the present invention may be practiced.

1 schematically shows a cross-sectional view of a uniflow scavenging large, low-speed turbocharged two-stroke crosshead internal combustion engine 100 for propulsion of a marine vessel, in accordance with an embodiment of the present invention. The engine 100 includes a scavenging air 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-sectional view). Each cylinder 101 has a cylinder wall 115 and includes a scavenging air inlet 102 arranged at the bottom of the cylinder 101 . The engine further includes a cylinder cover 112 and a piston 103 for each cylinder. A cylinder cover 112 is arranged on top of the cylinder 101 and has an exhaust valve 104 . The piston 103 is arranged movably in the cylinder along a central axis 113 between bottom dead center and top dead center. The fuel gas supply system is configured to inject fuel gas into the cylinder 101 during a compression stroke such that the fuel gas is mixed with the scavenge air and the mixture of the scavenge air and the fuel gas is compressed prior to ignition. a gas valve 105 (shown only schematically). The fuel gas valve 105 is arranged at least partially in the cylinder wall between the cylinder cover 112 and the scavenging air inlet 102 . The engine further includes a pilot pre-chamber unit 114 (shown only schematically) arranged at least partially within the cylinder wall 115 . The pilot pre-chamber unit 114 includes a pre-chamber, a pilot fuel valve housing, and a pilot fuel valve arranged in the pilot fuel valve housing, wherein the pre-chamber has a pre-chamber wall and passes through a first opening. open into the cylinder. The pre-chamber is configured to ignite a mixture of scavenge air and fuel gas in the cylinder. The pilot pre-chamber unit 114 further includes a first heat exchange channel having an inlet and an outlet for circulating a heat exchange fluid. Both the inlet and outlet of the first heat exchange channel are arranged in the pilot fuel valve housing. The scavenging air inlet 102 is fluidly connected to the scavenging air system. The piston 103 is shown in 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 a compression stroke, allowing the fuel gas to mix with the scavenging air and allowing the mixture of the scavenging air and fuel gas to be compressed prior to ignition. The fuel gas valve 105 injects fuel gas into the cylinder 101 at the start of the compression stroke of 0 degrees to 130 degrees from bottom dead center, that is, when the crankshaft is rotated 0 degrees to 130 degrees from the orientation at bottom dead center. It is preferably configured to do so. Preferably, the fuel gas valve 105 is connected to the crankshaft such that the piston moves past the scavenge air inlet 102 to prevent fuel gas from escaping through the exhaust valve 104 and the scavenge air inlet 102 . It is configured to start injection of fuel gas after the shaft has rotated several degrees from bottom dead center. The scavenge air system 111 includes a scavenge air receiver 110 and an air cooler 106 .

The engine 100 is preferably a dual-fuel engine having an auto cycle mode driven by fuel gas and a diesel cycle mode driven by an alternative fuel such as heavy oil or marine diesel oil. These dual-fuel engines have a dedicated alternative fuel supply system for injecting alternative fuels. Accordingly, optionally the engine 100 further comprises one or more fuel injectors 116 arranged within the cylinder cover 112 forming part of the alternative fuel supply system. When the engine 100 is driven on an alternative fuel, the fuel injector 116 is configured to inject an alternative fuel, eg, heavy oil, at the end of a high-pressure compression stroke.

2 shows a partial schematic cross-sectional view of a uniflow scavenging two-stroke crosshead internal combustion engine according to an embodiment of the present invention. A cylinder 101 , a cylinder cover 112 , a piston 103 , and an exhaust valve 104 are shown. The piston 103 is located at top dead center. The cylinder 101 has a cylinder wall 115 having a first pilot pre-chamber unit 114 and a second pilot pre-chamber unit 116 , the first and second pilot pre-chamber units 114 , 116 , each comprising a pre-chamber, a pilot fuel valve housing, a pilot fuel valve arranged in the pilot fuel valve housing, and a first heat exchange channel having an inlet and an outlet for circulating a heat exchange fluid, wherein the inlet and the outlet are respectively All are arranged in the pilot fuel valve housing. Both the pre-chambers of the first and second pilot pre-chamber units 114 , 116 open into the cylinder 101 through an opening formed in the cylinder wall 115 , and the pre-chambers are evacuated air and fuel in the cylinder. configured to ignite a mixture of gases.

3 shows a partial schematic cross-sectional view of a uniflow scavenging two-stroke crosshead internal combustion engine according to an embodiment of the present invention. This part corresponds to the part shown in FIG. 2 , but the cylinder 101 has a base member 117 and a pre-chamber member 118 , and the pre-chamber member 118 is disposed on the upper portion of the base member 117 . arranged and the cylinder cover 112 is arranged on top of the pre-chamber member 118 . The first and second pilot pre-chamber units 114 , 116 are arranged in the cylinder wall of the pre-chamber member 118 . This allows the pre-chamber member to be specially designed to handle high temperatures and pressures, for example by selecting appropriate materials.

4 is a partial schematic cross-sectional view of a uniflow scavenging two-stroke crosshead internal combustion engine according to an embodiment of the present invention. This part corresponds to the part shown in FIG. 2 , but is different in that the first and second pilot pre-chamber units 114 , 116 are arranged in the cylinder cover 112 .

5 is a schematic diagram of a pilot pre-chamber unit 114 for a two-stroke uniflow scavenging crosshead internal combustion engine in accordance with an embodiment of the present invention. The pilot pre-chamber unit 114 includes a pre-chamber 134 , a pilot fuel valve housing 130 , and a pilot fuel valve 132 arranged within the pilot fuel valve housing 130 . The pre-chamber 134 has a pre-chamber wall and an opening that opens into a cylinder of the engine. The pre-chamber 134 is configured to ignite a mixture of scavenge air and fuel gas within the cylinder. The pilot pre-chamber unit 114 further includes a first heat exchange channel 133 having an inlet 136 and an outlet 137 for circulating a heat exchange fluid. Both the inlet 136 and the outlet 137 are arranged in the pilot fuel valve housing 130 . In this embodiment, the pre-chamber 134 and the pilot fuel valve housing 130 are two separate elements connected together. The pre-chamber 134 and pilot fuel valve housing 130 may be connected using any suitable connection method, such as using bolted connections or welding.

6 shows a schematic diagram of a pilot pre-chamber unit 114 for a two-stroke uniflow scavenging crosshead internal combustion engine according to an embodiment of the present invention. The pilot pre-chamber unit 114 corresponds to the pilot pre-chamber unit described with reference to FIG. 5, but the pre-chamber 134 and the pilot fuel valve housing 130 are one element produced by a single process. It is different in that it is formed. The pre-chamber 134 and pilot fuel valve housing 130 may be cast together in a single casting process or formed as a single element using additive manufacturing.

7A is a cross-sectional view of a uniflow scavenging large-scale, low-speed turbocharged two-stroke crosshead internal combustion engine for propulsion of a marine vessel according to an embodiment of the present invention. The engine is a dual-fuel engine having an auto cycle mode driven by fuel gas and a diesel cycle mode driven by an alternative fuel such as heavy oil or marine diesel oil. Each cylinder has a cylinder wall and includes a scavenging air inlet (not shown) arranged at the bottom of the cylinder. The engine further includes a cylinder cover 112 and a piston 103 for each cylinder. A cylinder cover 112 is arranged on top of the cylinder and has an exhaust valve 104 . The piston 103 is arranged movably in the cylinder along a central axis between bottom dead center and top dead center. In the figure, the piston 103 is arranged at top dead center. The fuel gas supply system is configured to inject fuel gas into the cylinder during a compression stroke (when the engine is in gas mode) so that the fuel gas is mixed with the scavenge air and the mixture of scavenge air and fuel gas is compressed prior to ignition. one or more fuel gas valves (not shown) that allow The fuel gas valve is arranged at least partially in the cylinder wall between the cylinder cover 112 and the scavenging air inlet. The engine further includes two pilot pre-chamber units 131 , each pilot pre-chamber unit 131 comprising a pre-chamber 114 , a pilot fuel valve housing 130 , and a pilot fuel valve housing 130 . ) a pilot fuel valve 132 arranged within. The cylinder has a base member 117 and a pre-chamber member 118 , wherein the pre-chamber member 118 is arranged on top of the base member 117 and the cylinder cover 112 is a portion of the pre-chamber member 118 . arranged at the top. The pre-chamber 114 is arranged in the cylinder wall of the pre-chamber member 118 . The pre-chamber 114 opens into the cylinder through an opening formed in the cylinder wall of the pre-chamber member 118 . The scavenging air inlet is fluidly connected to the scavenging air system. The piston 103 is connected to a crankshaft (not shown) via a piston rod, a crosshead, and a connecting rod. The pilot fuel valve 132 is configured to inject a small amount of pilot fuel into the pre-chamber 114 at least when the engine is in gas mode. The pilot fuel valve 132 may be configured to inject a small amount of pilot fuel into the pre-chamber 114 to prevent the pilot fuel valve from clogging when the engine is driven purely on diesel. The pre-chamber 114 is configured such that the temperature and pressure within the pre-chamber 114 causes the pilot fuel to self-ignite. The pilot fuel oil may be heavy oil, marine diesel oil, or another fuel capable of self-ignition.

The engine further includes one or more fuel injectors 116 arranged within the cylinder cover 112 forming part of the alternative fuel supply system. When the engine 100 is driven on an alternative fuel, the fuel injector 116 is configured to inject an alternative fuel, eg, heavy oil, at the end of a compression stroke under high pressure.

FIG. 7B is an enlarged view of the pilot pre-chamber unit 131 on the right side shown in FIG. 7A . The pilot pre-chamber unit 131 includes a first heat exchange channel 145 for circulating a heat exchange fluid, having an inlet 136 and an outlet (not shown), wherein both the inlet 136 and the outlet are pilot It is arranged in the fuel valve housing 130 . The pilot pre-chamber unit 131 further comprises a second heat exchange channel 146 for circulating a heat exchange fluid, having an inlet 138 and an outlet (not shown), wherein both the inlet 138 and the outlet are A pilot fuel valve is arranged in the housing 130 . First and second heat exchange channels 145 , 146 extend inside both a portion of the wall of the pre-chamber 114 and a portion of the pilot fuel valve housing 130 . The first and second heat exchange channels 145 , 146 have a first portion for guiding the heat exchange fluid towards the first opening 144 of the pre-chamber, and the heat exchange fluid away from the first opening of the pre-chamber. and a second part for guiding (only the first part is shown in this cross-sectional view). The shape of the first part substantially corresponds to the shape of the second part. In this embodiment, the pre-chamber member 118 functions as a pre-chamber housing, the pre-chamber 114 being arranged within the pre-chamber housing, and the pre-chamber 114 supporting the pre-chamber housing. and a first contact portion 143 and a second contact portion 142 for securing the pre-chamber within the pre-chamber housing. In this embodiment, both the first contact portion 143 and the second contact portion 142 have an annular shape. The pre-chamber housing includes a first insulating space 141 (eg, filled with gas) formed between the first contact portion 143 and the second contact portion 142 to limit heat exchange between the pre-chamber 114 and the engine. has). The pre-chamber further has a third contact 147 for supporting the pre-chamber housing. In the present embodiment, the third contact portion 147 has an annular shape. The pre-chamber housing further has a second insulating space 140 formed between the second contact portion 142 and the third contact portion 147 .

While some embodiments have been described and shown in detail, the invention is not limited thereto, but may be embodied in other ways within the scope of the subject matter defined in the claims that follow. In particular, it is to be understood that other embodiments may be utilized and structural and functional modifications may be made without departing from the scope of the present invention.

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

As used herein, the term "comprises/comprising" is used to specify the presence of a recited feature, integer, step or element, but one or more other features, integers, steps, configurations. It should be emphasized that this does not exclude the presence or addition of elements or groups thereof.

Claims (11)

A two-stroke uniflow scavenge crosshead internal combustion engine comprising at least one cylinder, a cylinder cover, a piston, a fuel gas supply system, and a scavenging air system, comprising:
the cylinder has a cylinder wall,
the cylinder cover is arranged on top of the cylinder and has an exhaust valve,
the piston is arranged movably within the cylinder along a central axis between bottom dead center and top dead center;
The scavenging air system has a scavenging air inlet arranged at the bottom of the cylinder,
The fuel gas supply system is arranged at least partially on the cylinder wall and configured to inject fuel gas into the cylinder during a compression stroke such that the fuel gas is mixed with the scavenge air and the mixture of the scavenge air and the fuel gas is compressed prior to ignition. including a fuel gas valve allowing it to be
the engine further comprising a pilot pre-chamber unit comprising at least one pre-chamber, a pilot fuel valve housing, and a pilot fuel valve arranged within the pilot fuel valve housing;
the at least one pre-chamber has a pre-chamber wall,
the pilot pre-chamber unit is configured to ignite a mixture of scavenge air and fuel gas within the cylinder;
the pilot pre-chamber unit further comprising a first heat exchange channel for circulating a heat exchange fluid having an inlet and an outlet;
wherein both the inlet and the outlet are arranged in the pilot fuel valve housing. The method according to claim 1,
and the first heat exchange channel extends inside both a portion of the pre-chamber wall and a portion of the pilot fuel valve housing. The method according to claim 1 or 2,
wherein the at least one pre-chamber and the pilot fuel valve housing are two separate elements connected together. The method according to claim 1 or 2,
wherein the at least one pre-chamber and the pilot fuel valve housing are formed as one element produced in a single process. 5. The method according to any one of claims 1 to 4,
said at least one pre-chamber comprising a first opening opening into a cylinder, said first heat exchange channel comprising a first portion for guiding a heat exchange fluid towards said first opening of said at least one pre-chamber; a second portion for guiding a heat exchange fluid away from the first opening of the at least one pre-chamber, wherein a shape of the first portion corresponds to a shape of the second portion; Scavenging crosshead internal combustion engine. 6. The method of claim 5,
The pilot pre-chamber unit further comprises a second heat exchange channel for circulating a heat exchange fluid having an inlet and an outlet and extending through the pilot fuel valve housing and the pre-chamber wall, both the inlet and the outlet is arranged in the pilot fuel valve housing. 7. The method of claim 6,
The pilot pre-chamber unit further comprises a third heat exchange channel for circulating a heat exchange fluid, the third heat exchange channel having an inlet and an outlet and extending through the pilot fuel valve housing and the pre-chamber wall, both the inlet and the outlet is arranged in the pilot fuel valve housing. 8. The method according to any one of claims 1 to 7,
and the first, second and third heat exchange channels are arranged rotationally symmetrically. 9. The method according to any one of claims 1 to 8,
The engine further comprises a pre-chamber housing, wherein the at least one pre-chamber is arranged within the pre-chamber housing, the at least one pre-chamber supporting the pre-chamber housing and the pre-chamber housing having at least a first contact and a second contact for securing the at least one pre-chamber therein;
wherein the pre-chamber housing has a first insulating space formed between the first contact portion and the second contact portion to limit heat exchange between the at least one pre-chamber and the engine. Crosshead internal combustion engine. 10. The method of claim 9,
wherein the at least one pre-chamber and the temperature control channel are fabricated by a single additive manufacturing process. 11. A pilot pre-chamber unit for a two-stroke uniflow scavenge crosshead internal combustion engine comprising at least one cylinder according to any one of the preceding claims, comprising:
The pilot pre-chamber unit includes a pre-chamber, a pilot fuel valve housing, and a pilot fuel valve arranged in the pilot fuel valve housing, wherein at least one pre-chamber has a pre-chamber wall, the pilot pre-chamber The unit is configured to ignite a mixture of scavenge air and fuel gas in a cylinder, the pilot pre-chamber unit further comprising a first heat exchange channel for circulating a heat exchange fluid having an inlet and an outlet, the inlet and the all of the outlets are arranged in the pilot fuel valve housing.

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