A fuel valve for injecting fuel into a cylinder of a large turbocharged two-stroke uniflow scavenged internal combustion engine, and an engine equipped with such a fuel valve

Abstract

To provide a fuel injection valve for a large turbocharged two-stroke uniflow scavenged internal combustion engine.SOLUTION: The valve comprises: a fuel valve housing with an axis X, a proximal end and a distal end; a valve needle that rests on a valve seat in a closed position and leaves the valve seat in an open position; and a nozzle 40 disposed at the distal end. A body of the nozzle has a region extending along the axis X from a base at a proximal end to a closed distal end, and comprises: an elongated portion 43 between the base and the distal end; an inlet for receiving a liquid fuel from the fuel valve housing; a plurality of nozzle bores 45 each opening to an outer surface of the nozzle body at a different radial angle; and a single main bore extending longitudinally from the inlet into the nozzle body. The nozzle is connected to the main bore by an individual supply passage that is arranged at an angle to the main bore and to itself. The valve needle comprises a distal section with a cylindrical end section carried by a shank. The cylindrical end slidably fits in the main bore in order to fluidically disconnect the supply passage from the main bore when the valve needle is in the closed position.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The subject matter disclosed by the present application (hereinafter referred to as the present disclosure) relates to a fuel valve that injects liquid fuel into a cylinder of a large turbocharged two-stroke uniflow scavenging internal combustion engine. Background

[0002] A large turbocharged two-stroke uniflow scavenging crosshead internal combustion engine is typically used as a prime mover for large ocean-going vessels such as container ships or power plants.

[0003] In the cylinder of this type of engine, only one exhaust valve is provided at the center of the cylinder cover, i.e., the upper part of the cylinder, and scavenging ports for piston control are provided in a ring shape at the lower part of the cylinder liner. The gas transport direction in the cylinder is always from bottom to top, hence the name uniflow scavenging. The scavenging ports are arranged obliquely. This is to generate a vortex in the gas in the combustion chamber.

[0004] Around the exhaust valve arranged at the center of the cylinder cover, two or three fuel valves are arranged. The nozzle of the fuel valve protrudes into the combustion chamber. The fuel valve is arranged at the peripheral part of the cylinder cover. That is, it is not arranged at the center part. The nozzle holes of the nozzle are arranged so as to face the direction of the vortex (swirl) into the combustion chamber and are directed in a direction away from the cylinder wall. Sometimes, one nozzle hole of the nozzle may be directed against the vortex in the combustion chamber.

[0005] The nozzle is attached to the front end (distal end) of the fuel valve. The fuel valve has a vertically long housing. This housing penetrates the cylinder cover, the rear end (proximal end) protrudes from the upper surface of the cylinder cover, and the nozzle at the front end (distal end) protrudes into the combustion chamber.

[0006] Known nozzles for crosshead-type large two-stroke diesel engines typically have an elongate body. This nozzle body has a cylindrical portion with a straight main bore. This main bore leads from the base end of the nozzle, which is at the proximal end of the nozzle body, to a nozzle hole located in the vicinity of the tip (distal end) of the nozzle body. The tip or distal end may be rounded or flat, but is closed. This is because the nozzle hole must not be directed downward with respect to the piston (since when the piston is at top dead center, i.e., at the moment of fuel injection in a compression ignition engine, the upper surface of the piston is very close to the tip of the nozzle). For this reason, the nozzle holes are mainly directed laterally with respect to the main axis of the nozzle / fuel valve and are typically approximately perpendicular to the main axis of the engine cylinder. Typically, each nozzle is provided with 3 to 7 nozzle holes. All of these are connected to the main bore.

[0007] Typically, known fuel valves for injecting liquid fuel comprise a conical valve seat and an axially displaceable valve needle cooperating therewith to control the flow of fuel to the nozzle. The front portion of the valve needle consists of a distal cylindrical portion that is received without clearance within the main bore and acts as a slide valve for closing the nozzle holes when the valve needle is in the closed position. Thereby, the so-called sac volume, i.e., the residual volume (RV) of fuel within the space formed by the main bore within the nozzle, is significantly reduced. Without such a slide valve structure, the amount of residual fuel within the main bore (and within the nozzle holes) would drip into the combustion chamber after the end of fuel injection, adversely affecting fuel consumption, reliability, and exhaust gases.

[0008] Since the nozzle body protrudes into the combustion chamber, it is exposed to the high-temperature gases of the combustion chamber, and a part of the nozzle body reaches a relatively high temperature of up to approximately 400°C. In the case of an engine operated with heavy oil, the temperature of the incoming fuel is approximately 140°C. That is, the incoming fuel within the main bore exiting the nozzle through the nozzle holes has a significantly lower temperature than the gases surrounding the outer surface of the nozzle body. Therefore, the material of the nozzle body is exposed to a considerable temperature gradient, and stress occurs in the material of the nozzle.

[0009] Therefore, when the nozzle is exposed to the high operating temperature gas in the combustion chamber, due to the thermal fatigue of the material and the strong cooling effect of the injected fuel, there is a risk of cracks occurring in the nozzle region where the nozzle holes are located, especially between the nozzle holes and the nozzle holes.

[0010] This problem cannot be solved simply by increasing the distance between the nozzle holes, increasing the material between the nozzle holes, and reducing the temperature gradient. This is because increasing the diameter of the nozzle is highly undesirable because it is likely to increase the amount of heat transferred from the combustion chamber to the nozzle. In addition, two or three fuel valves are arranged at the peripheral part of the cylinder cover, and since the radial spread of the nozzle holes is limited to an angle of about 110°, it is impossible to simply increase the radial distance between the nozzle holes. This is especially true when there is a slide valve in the nozzle. The main hole in the nozzle is required to have a certain diameter, and as a result, the wall thickness of the nozzle body is restricted. Furthermore, in a fuel valve having a slider in the nozzle body, when the nozzle holes inject fuel simultaneously, it is required that the nozzle holes open at substantially the same axial distance from the base of the nozzle to the main hole.

[0011] US5765755A discloses an injection rate shaping nozzle assembly for a fuel injection device. This nozzle assembly includes a closed nozzle valve element and an injection rate shaping control device having an injection spill circuit. The injection leakage circuit allows a portion of the injected fuel to escape in order to produce a predetermined time variation in the flow rate of the fuel injected into the combustion chamber. The spill circuit includes a spill passage (escape passage) integrally formed in the nozzle valve element. The injection rate shaping control device can have a spill acceleration chamber formed in the nozzle valve element to cause a sudden increase in the spill flow rate (escape flow rate). Also, a spill circuit purge device is provided to remove fuel from the outflow circuit and the acceleration chamber during individual injection events, thereby ensuring an effective spill fuel flow that is not obstructed during the next spill event. The purge device includes a purge passage formed with a predetermined size to limit the flow of purge gas while ensuring sufficient fuel removal from the injection spill circuit and avoiding an excessive purge gas flow. The purge passage can have an annular clearance gap formed between the nozzle valve element and the nozzle housing wall, or can have an orifice passage formed in an inner portion of the nozzle valve element. Abstract

[0012] In view of the above, an object of the present invention is to provide a fuel valve for injecting liquid fuel into a crosshead type large two-stroke uniflow scavenging internal combustion engine that overcomes or at least reduces the above problems.

[0013] The above problems and other problems are solved by the features described in the independent claims. More specific implementations will become apparent from the dependent claims, the specification, and the drawings.

[0014] According to a first aspect, there is provided a fuel valve for injecting liquid fuel into a crosshead type large two-stroke turbocharged uniflow scavenging internal combustion engine. This fuel valve has a longitudinally elongated fuel valve housing having a longitudinal axis, a proximal end, and a distal end; an axially displaceable valve needle having a closed position seated on a valve seat and an open position disengaged from the valve seat; a nozzle disposed at a distal end of the longitudinally elongated fuel valve housing; comprising, the nozzle comprising a nozzle body having a region extending from a base at a proximal end of the nozzle body along the longitudinal axis to a closed distal end of the nozzle body, the base being attached to the fuel valve housing, the nozzle body having, a longitudinally elongated (preferably cylindrical) portion between the base and the closed distal end; an inlet for receiving liquid fuel from the fuel valve housing and opening into the base; a plurality of straight nozzle holes opening onto an outer surface of the nozzle body at respectively different radial angles; a single straight main hole extending longitudinally from the inlet into the nozzle body; and comprising, at least two of the plurality of straight nozzle holes are each connected to the main hole by an individual supply passage, the individual supply passage being disposed obliquely with respect to the nozzle hole and the main hole to which the individual supply passage is connected, the valve needle has a distal portion having a cylindrical end supported by a shank, the cylindrical end fitting slidably and snugly into the main hole so as to fluidly isolate the supply passage from the main hole when the valve needle is in the closed position.

[0015] By providing individual supply passages angled with respect to the straight nozzle holes and the nozzle main hole, a high degree of freedom is provided for selecting the angle of the straight nozzle holes with respect to the main axis and the position of these nozzle holes in the nozzle body material. Thereby, without increasing the overall size of the nozzle, in particular without increasing the diameter of the cylindrical portion of the nozzle, it is possible to select the position and orientation of the nozzle holes to have more nozzle body material between adjacent nozzle holes so as to reduce the formation of cracks related to the thermal coefficient and thermal stress.

[0016] In an example of an implementation form of the first grasping method, the individual supply path is directed away from the longitudinal axis at a first angle with respect to the longitudinal axis when viewed from the position where the individual supply path connects to the main hole. As a result, the "base" of the nozzle hole is arranged more radially outward, whereby the distance between adjacent nozzle holes becomes longer, and accordingly, more nozzle body material is present between adjacent nozzle holes. In this context, the "base" is located at the location where the straight nozzle hole connects to the individual supply path.

[0017] In an example of an implementation form of the first grasping method, the straight nozzle hole is directed away from the longitudinal axis X at a second angle with respect to the longitudinal axis X when viewed from the position where the nozzle hole connects to the individual supply path. However, the second angle is larger than the first angle.

[0018] In an example of an implementation form of the first grasping method, the individual supply path is a straight hole and preferably has a rounded, i.e., round, end in order to reduce the stress of the nozzle hole material.

[0019] In an example of an implementation form of the first grasping method, the cylindrical end fluidly connects the individual supply path to the straight main hole when the valve needle is in the open position.

[0020] In an example of an implementation form of the first grasping method, the cylindrical end covers the opening of the individual supply path to the straight main hole when the valve needle is in the closed position.

[0021] In an example of an implementation form of the first grasping method, the cylindrical end does not cover the opening of the individual supply path to the straight main hole when the valve needle is in the open position.

[0022] In an example of an implementation form of the first grasping method, the individual supply path opens into the main hole at a predetermined axial distance from the inlet, and the cylindrical end reaches a position beyond the predetermined axial distance in the closed position of the valve needle.

[0023] In an example of an implementation form of the first grasping method, the axially displaceable valve needle is slidably received within the longitudinal bore of the longitudinally extended valve housing. In the closed position, the valve needle seats on the valve seat. The valve seat is preferably a conical valve seat. In the open position, the valve needle lifts from the valve seat. The valve needle is preferably biased towards the closed position. Preferably, a fuel chamber is provided that surrounds the valve needle and opens into the valve seat.

[0024] In an example of an implementation form of the first grasping method, the fuel valve includes a fuel inlet port for connection to a liquid fuel source in the longitudinally extended fuel valve housing.

[0025] In an example of an implementation form of the first grasping method, all of the plurality of straight nozzle holes have substantially equal cross-sectional areas or diameters, and also preferably have substantially equal lengths.

[0026] In an example of an implementation form of the first grasping method, all of the plurality of straight nozzle holes have equal diameters, and also preferably, the individual supply path has a diameter larger than the diameter of the straight nozzle holes.

[0027] In an example of an implementation form of the first grasping method, the straight main hole is formed in a bush. The bush is tightly fitted into the bore of the valve body.

[0028] In an example of an implementation form of the first grasping method, the cylindrical end is hollow to form a fluid passage. The fluid passage preferably opens proximally with respect to the outside of the handle portion and opens distally in the axial direction.

[0029] In one example of the implementation form of the first grasping method, the plurality of straight nozzle holes each open on a cylindrical surface.

[0030] In one example of the implementation form of the first grasping method, preferably a rounded transition surface is provided between a substantially cylindrical surface and a flat distal end face of the nozzle body.

[0031] In one example of the implementation form of the first grasping method, the plurality of straight nozzle holes open on the cylindrical surface and / or the transition surface.

[0032] In one example of the implementation form of the first grasping method, the plurality of straight nozzle holes each have nozzle axes I, II, III, IV, V, and the nozzle axes I, II, III, IV, V of each nozzle hole are arranged at an obtuse angle α with respect to the main direction X.

[0033] In one example of the implementation form of the first grasping method, the respective radial components of the nozzle axes I, II, III, IV, V with respect to the main axis X are distributed over a sector having an arc of less than 120 degrees, preferably less than 110 degrees, more preferably less than 100 degrees, and are preferably distributed substantially evenly.

[0034] In one example of the implementation form of the first grasping method, at least three of the plurality of straight nozzle holes are connected to the straight main hole by the individual supply passages arranged obliquely with respect to themselves and the straight main hole.

[0035] According to the second grasping method, a crosshead type large two-stroke turbocharged uniflow scavenging internal combustion engine provided with any one of the fuel valves or its implementation forms according to the first grasping method is provided.

[0036] These and other aspects of the present invention will become more apparent from the examples described below.

Brief Description of the Drawings

[0037] Hereinafter, the present invention will be described in more detail with reference to the exemplary embodiments shown in the drawings.

Figure 1

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Figure 4

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Figure 10

Figure 11

Figure 12

[0038] In the following detailed description, exemplary embodiments will be used to describe a fuel valve and a large two-stroke engine in which the fuel valve is used. Figures 1 to 3 depict a turbocharged large low-speed two-stroke internal combustion engine. This engine has a crankshaft 22 and a crosshead 23. Figure 3 schematically shows a turbocharged large low-speed two-stroke internal combustion engine together with its intake system and exhaust system. In this exemplary embodiment, the engine has six cylinders in series. Each cylinder is formed from a cylinder liner 1. A turbocharged large two-stroke internal combustion engine usually has five to sixteen cylinders arranged in series. These cylinders are carried by an engine frame 24. Such an engine can be used, for example, as the main engine of an ocean-going ship or as a stationary engine for driving a generator in a power plant. The total output of the engine can be in the range of, for example, 5000 to 110000 kW.

[0039] The engine can be a two-stroke uniflow diesel engine (compression ignition type engine). In the lower region of the cylinder liner 1, a ring-shaped scavenging port 19, which is a port controlled by a piston, is provided. An exhaust valve is arranged at the center of the top of the cylinder liner 1. Therefore, the flow in the combustion chamber is always from bottom to top, and the engine is of the so-called uniflow type. Scavenging air is led to the scavenging port 19 of each cylinder through a scavenging receiver 2. Each cylinder is formed by a cylinder liner 1 respectively. The reciprocating piston 21 in the cylinder liner 1 compresses the scavenging air, and fuel is injected through the nozzles of two or three fuel valves 30 arranged on the cylinder cover 26. Combustion occurs and exhaust gas is generated. When the exhaust valve 4 opens, the exhaust gas flows through an exhaust duct 20 connected to the cylinder 1 to an exhaust receiver 3, and further proceeds to a turbine 6 of a turbocharger 5 through a first exhaust pipe 18. From there, the exhaust gas is exhausted through a second exhaust pipe 7. The turbine 6 drives a compressor 9 via a shaft 8. Air is supplied to the compressor 9 from an air inlet 10.

[0040] The compressor 9 feeds the compressed scavenging air into the air supply pipe 11 connected to the air supply receiver 2. The scavenging air in the scavenging pipe 11 passes through an intercooler 12 for cooling the air supply. The cooled air supply passes through an auxiliary blower 16 driven by an electric motor 17. The auxiliary blower 16 compresses the flow of the air supply toward the air supply receiver 2 when the engine is at low load or partial load. When the load of the engine is high, since the compressor 9 of the turbocharger can supply sufficiently compressed scavenging air, the auxiliary blower 16 is bypassed by a check valve 15.

[0041] The cylinder is formed within the cylinder liner 1. The cylinder liner 1 is carried by a cylinder frame 25. The cylinder frame 25 is supported by a period frame 24.

[0042] FIG. 4 shows an embodiment of one of two or three fuel valves 30 mounted within the through-bore of the cylinder cover 26 of each cylinder. The fuel valve 30 is mounted in the through-bore of the cylinder cover 26 with the rear end 31 protruding from the upper side of the cylinder cover 26 and the distal end (tip) of the nozzle 40 slightly protruding into the combustion chamber. The fuel valve 30 has an elongate fuel valve body 32. The fuel valve body 32 has a nozzle holder at its distal end 33. The nozzle holder couples the nozzle 40 to the elongate fuel valve body 32. Liquid fuel (e.g., ethanol, methanol, diesel, heavy oil) is supplied by the fuel valve 30 through the nozzle 40 into the combustion chamber 14. The liquid fuel is supplied to the combustion chamber 14 in a controlled manner and at a timed interval. The fuel valve 30 shown in FIG. 4 has an elongate outer housing 32. The housing 32 has a head at its proximal end 31, by which the fuel valve 30 may be attached to the cylinder cover 26 (in a known manner), and the fuel valve 30 may also be connected to a fuel pump (not shown) of the internal combustion engine.

[0043] The head of the proximal end 31 has a fuel inlet 83. The fuel inlet 83 is connected to a duct extending through the valve body 32 and a flow path. The axially displaceable valve needle 35 is slidably disposed within the valve housing 32 and has an open position where the valve needle 35 (preferably conical) separates from the valve seat 36, and a closed position where the valve needle 35 (the portion corresponding to the valve seat 36) seats on the valve seat 36 to close the valve. The valve needle is elastically biased toward the closed position by an elastic means formed by a helical spring 83 in this embodiment. The lift of the valve needle 35 against the force biased by the helical spring 83 is caused by the pressure of the fuel supplied to the fuel valve 30. Specifically, it is caused by the pressure acting on the surface of the valve needle 35 or acting on a piston or plunger connected to the valve needle 35 so as to actuate the valve needle 35. A fuel chamber 68 surrounding the valve needle 35 and opening to the valve seat 36 is provided. The fuel valve 30 carries a nozzle 40 at its distal end 33. The nozzle 40 is configured to protrude into the combustion chamber 14 of the engine cylinder liner 1 when the fuel valve 30 is attached to the cylinder cover 26.

[0044] In this embodiment, the fuel valve includes an axially movable valve needle 35. The valve needle 35 has a conical portion, which cooperates with a conical seat portion 36 within the longitudinally extending housing 32 of the fuel valve 30.

[0045] Figure 12 illustrates how the nozzle 40 is arranged at the edge of the cylinder cover 26. Figure 12 also illustrates the direction of fuel injection. The direction of fuel injection corresponds to the directions of the axes I, II, III, IV, V of the straight nozzle holes 45 of the nozzle 40. The swirling direction of the gas in the combustion chamber is illustrated by the curved dashed arrow 66.

[0046] Figure 5 shows a fuel valve 30 according to another embodiment. This embodiment is the same as the embodiment of Figure 4 except that it includes a booster pump for amplifying the pressure of the fuel supplied to the fuel valve 30. The main component of the booster pump is the booster plunger 80. The other components of the fuel valve 30 and the nozzle 40 according to this embodiment are conceptually the same as those of the fuel valve in Figure 4.

[0047] Figures 6 through 11 show the distal portions of the nozzle 40 and the valve needle 35 in greater detail.

[0048] The nozzle 40 has a nozzle body extending from a proximal base 42 to a closed distal end 44 that forms the tip of the nozzle 40. The cylindrical portion 43 of the nozzle body extends from the base to the distal end 44. The nozzle body is made of a suitable material, such as a suitable alloy well-known in the art.

[0049] The inlet 48 opens into the base 42 to receive liquid fuel from the fuel valve 30 when the valve needle 35 is in the open position. A single straight main bore 50 extends longitudinally from the inlet 48 into the nozzle body. In this embodiment, the straight main bore 50 is formed within a bush 51, and the bush 51 is tightly fitted within a bore 51 in the valve body, for example, by shrink fitting. However, depending on the embodiment, the nozzle body may be made from a single piece and the nozzle may be configured without the bush 51.

[0050] The closed distal end (tip) 44 has a substantially planar end face 47 with a circular or oval outer shape. The end face 47 is connected to the cylindrical portion via a curved or rounded transition surface 46.

[0051] The nozzle 40 is provided with a plurality of linear nozzle holes 45. The nozzle 40 may have any desired number of nozzle holes 45. Preferably, it has from 3 to 7 nozzle holes 45, more preferably from 3 to 6 nozzle holes 45, and most preferably 5 or 6 nozzle holes 45. The nozzle 40 according to this embodiment has 5 nozzle holes 45.

[0052] Each straight nozzle hole 45 opens to the outer surface of the nozzle body 43 at a different radial angle, and when the fuel valve 30 is opened, as shown in FIG. 12, it causes a fan-shaped fuel jet in the combustion chamber. Each straight nozzle hole 45 opens to the outer surface of the nozzle body 43 at a different radial angle. Preferably, the nozzle hole 45 opens to the cylindrical surface 43 and / or and / or the transition surface 46.

[0053] The nozzle holes 45 each have nozzle axes I, II, III, IV, V (FIG. 10). The nozzle axes I, II, III, IV, V of each nozzle hole 45 are arranged at an obtuse angle α with respect to the main axis X. This obtuse angle α may be different for each nozzle hole 45. The radial components of each nozzle axis I, II, III, IV, V with respect to the main axis X are distributed over a fan-shaped sector having an arc of less than 120 degrees, preferably less than 110 degrees, and more preferably less than 100 degrees. The radial components of each nozzle axis (I, II, III, IV, V) with respect to the main axis X are substantially evenly distributed over the circular cross-section in order to maximize the amount of nozzle body material between the individual nozzle holes 45.

[0054] The base 42 is provided with an inlet port 48 for receiving fuel from the fuel valve 30. The main hole 50 extends from the inlet port 48 into the nozzle body in the direction along the main axis X and into the cylindrical portion 43 and reaches a position near the distal end 44 of the nozzle body. The main hole 50 is connected to a plurality of individual supply passages 49 that each lead to a nozzle hole 45. Each individual supply passage 49 is arranged at an angle with respect to the axis of the straight main hole 50 and the axis of the straight nozzle hole 45 to which the individual supply passage 49 is connected.

[0055] The cross-sectional area of the main hole 50 is substantially larger than the total cross-sectional area of the supply passages 49. The total cross-sectional area of the supply passages 49 is substantially equal to the total cross-sectional area of the nozzle holes 45.

[0056] By using individual supply passages 49 respectively to connect each nozzle hole 45 to the main hole 50, the plurality of nozzle holes 45 can be arranged in such a way as to maximize the amount of material of the nozzle body between them. Also, the axes I, II, III, IV, V of the nozzle holes 45 can be arranged so that the fuel jets cover the desired circular sectors.

[0057] In some embodiments, the inlet port 48 is formed by a bore having a diameter larger than the diameter of the main hole 50. Alternatively, the inlet port 48 can have the same diameter as the main hole.

[0058] In the nozzle 40, the nozzle holes 45 are widely dispersed, as a result, the nozzle material between the nozzle holes 45 increases, and the resistance to crack formation is improved. The nozzle 40 provides uniform inlet conditions to each nozzle hole 45 in order to form a substantially uniform fuel jet.

[0059] The valve needle 35 comprises a distal portion having a cylindrical end 39 carried by the shank 38. The cylindrical end 39 fits slidably and snugly into the straight main hole 50 and covers the opening from the individual supply passage 49 to the main hole 50 when the valve needle 35 is in the closed position, as shown in FIGS. 7, 9 and 11. For this reason, when the valve needle 35 is in the closed position, the cylindrical end 39 disconnects the individual supply passage 49 from the main hole 50. Thus, the fuel in the space between the valve seat 36 and the distal end of the main hole 50 is prevented from leaking into the combustion chamber 14 when the valve needle 35 is in the closed position.

[0060] The cylindrical end 39 is hollow to form a fluid passage 71 for fuel from the proximal side of the cylindrical end 39 to the distal side of the cylindrical end 39. The fluid passage 71 opens proximally with respect to the outside of the shank 38 and opens distally in the axial direction.

[0061] As shown in FIG. 8, the cylindrical end 39 does not cover the opening from the individual supply passage 49 to the main hole 50 when the valve needle 35 is in the open position. For this reason, the cylindrical end 39 fluidly connects each individual supply passage 49 to the main hole 50 when the valve needle 35 is in the open position.

[0062] Each individual supply passage 49 opens into the main hole at a predetermined axial distance from the inlet 48. The cylindrical end portion 39 reaches a position beyond the predetermined axial distance in the closed position of the valve needle 35, preventing the flow of fuel into each individual supply passage 49.

[0063] In some embodiments, the individual supply passage 49 is directed away from the longitudinal axis X at a first angle with respect to the longitudinal axis X as seen from the position where the individual supply passage 49 connects to the main hole 50. As a result, the "base" of the nozzle hole 45 is disposed more radially outward, thereby increasing the distance between adjacent straight nozzle holes 45 and thus increasing the amount of nozzle body material between adjacent straight nozzle holes 45. In this context, the position of the "base" is the position where the straight nozzle hole 45 connects to the individual supply passage 49.

[0064] In some embodiments, the straight nozzle hole 45 is directed away from the longitudinal axis X at a second angle with respect to the longitudinal axis X as seen from the position where the nozzle hole 45 connects to the individual supply passage 49. Here, the second angle is greater than the first angle.

[0065] In one example of the implementation of the first approach, the individual supply passage 49 is a straight hole and preferably has a rounded, i.e., round end (the "base" or in the vicinity thereof) to reduce stress in the nozzle hole material.

[0066] The present invention has been described using various embodiments. However, upon examining the specification, drawings, and claims of the present application, those skilled in the art will understand that there are many variations in addition to the described embodiments in implementing the invention described in the claims, and will also be able to embody them. The terms "comprising", "having", and "including" described in the claims do not exclude the existence of elements or steps not described. Even if it is not explicitly stated that there are a plurality of elements described in the claims, it does not exclude the existence of a plurality of such elements. Even if some matters are described in separate dependent claims, it does not exclude implementing them in combination, and benefits can be obtained by implementing them in combination. The reference signs used in the claims shall not be construed as limiting the scope of the invention.

Claims

1. A fuel valve for injecting liquid fuel into a crosshead type large two-stroke turbocharged uniflow scavenged internal combustion engine, comprising: a longitudinally elongated fuel valve housing having a longitudinal axis, a proximal end, and a distal end; an axially displaceable valve needle having a closed position seated on a valve seat and an open position disengaged from the valve seat; a spray nozzle disposed at the distal end of the longitudinally elongated fuel valve housing; wherein the spray nozzle comprises a nozzle body having a region extending from a base at the proximal end of the nozzle body along the longitudinal axis to a closed distal end of the nozzle body, the base being attached to the fuel valve housing, the nozzle body comprising: a longitudinally elongated portion between the base and the closed distal end; an inlet for receiving liquid fuel from the fuel valve housing and opening into the base; a plurality of straight nozzle holes opening on the outer surface of the nozzle body at different radial angles; a single straight main hole extending longitudinally from the inlet into the nozzle body; wherein at least three of the plurality of straight nozzle holes are connected to the straight main hole by individual supply passages disposed obliquely with respect to the straight main hole and themselves; the valve needle having a distal portion with a cylindrical end supported by a shank, the cylindrical end slidingly and snugly fitting into the straight main hole so as to fluidly disconnect the individual supply passage from the straight main hole when the valve needle is in the closed position. A fuel valve.

2. The fuel valve according to claim 1, wherein the cylindrical end fluidly connects the individual supply passage to the straight main hole when the valve needle is in the open position.

3. The fuel valve according to claim 1, wherein the cylindrical end covers an opening of the individual supply passage into the straight main hole when the valve needle is in the closed position.

4. The fuel valve according to claim 2, wherein the cylindrical end does not cover an opening of the individual supply passage into the straight main hole when the valve needle is in the open position.

5. The fuel valve according to claim 1, wherein the individual supply passage opens into the straight main hole at a predetermined axial distance from the inlet, and the cylindrical end reaches a position beyond the predetermined axial distance in the closed position of the valve needle.

6. ​ The valve needle is slidably received within the longitudinal bore of the longitudinally elongated fuel valve housing, and the valve needle seats on the valve seat in the closed position and is unseated from the valve seat in the open position, the fuel valve according to claim 1.

7. The fuel valve according to claim 1, wherein the longitudinally elongated fuel valve housing is provided with a fuel inlet port for connection to a liquid fuel source.

8. The fuel valve according to claim 1, wherein all of the plurality of straight nozzle holes have equal cross-sectional areas or diameters.

9. The fuel valve according to claim 1, wherein the straight main hole is formed in a bush, and the bush is tightly fitted into the bore of the nozzle body.

10. The fuel valve according to claim 1, wherein the cylindrical end portion is hollow to form a fluid passage.

11. The fuel valve according to claim 1, wherein all of the plurality of straight nozzle holes open onto the surface of the cylindrical end portion.

12. The fuel valve according to claim 1, having a rounded transition surface between the surface of the cylindrical end portion and the flat distal end face of the nozzle body.

13. The fuel valve according to claim 12, wherein all of the plurality of straight nozzle holes open onto the surface of the cylindrical end portion or the transition surface.

14. The fuel valve according to claim 1, wherein each of the plurality of straight nozzle holes has a nozzle axis disposed at an obtuse angle with respect to the longitudinal axis.

15. The fuel valve according to claim 14, wherein the radial components of the respective nozzle axes of the plurality of straight nozzle holes with respect to the longitudinal axis are distributed over a sector having an arc of less than 120 degrees.

16. A crosshead type large two-stroke turbocharged uniflow scavenged internal combustion engine comprising the fuel valve according to any one of claims 1 to 15.

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