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

Abstract

This relates to a fuel valve for injecting liquid fuel into the cylinder of a large turbocharged two-stroke uniflow scavenging internal combustion engine. [Solution] In a fuel injection valve for injecting fuel into a large two-stroke turbocharged uniflow scavenging internal combustion engine, the cylindrical distal portion 39 of the axially displaceable valve needle 35 is positioned inside the nozzle 40 and cooperates with the valve seat in the valve body to close the injection valve. A seal ring 52 is provided on the cylindrical distal portion 39 of the valve needle 35.

Description

Technical Field

[0001] The subject matter disclosed herein (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] Large turbocharged two-stroke uniflow scavenging crosshead internal combustion engines are typically used as prime movers for large ocean-going vessels such as container ships and power plants.

[0003] In the cylinder of this type of engine, only one exhaust valve is provided in the cylinder cover, i.e., the center of the upper part of the cylinder, and scavenging ports controlled by the piston 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 swirl in the gas in the combustion chamber.

[0004] In the cylinder cover, two or three fuel valves are arranged around the centrally arranged exhaust valve. The nozzles of the fuel valves protrude into the combustion chamber. The fuel valves are arranged at the peripheral part of the cylinder cover. That is, they are not arranged at the center. The nozzle holes of the nozzles 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 elongated body. This nozzle body has a cylindrical section with a straight main bore. This main bore runs from the proximal end of the nozzle at the proximal end of the nozzle body to a nozzle hole located near the distal end of the nozzle body. The distal end may be rounded or flat, but it is closed. This is because (when the piston is at top dead center, i.e., at the moment of fuel injection in a compression-ignition engine, the top surface of the piston is very close to the nozzle hole,) the nozzle hole must not face downwards relative to the piston. For this reason, the nozzle hole is oriented mainly laterally with respect to the main axis of the nozzle / fuel valve, and is typically nearly perpendicular to the main axis of the engine cylinder. Typically, each nozzle has 3 to 7 nozzle holes, all of which are connected to the main bore.

[0007] Typically, known fuel valves for injecting liquid fuels comprise a conical valve seat and a cooperating axially displaceable valve needle to control the flow of fuel to the nozzle. The forward portion of the valve needle consists of a distal cylindrical portion that is tightly received within the main bore and acts as a slide valve to close the nozzle bore when the valve needle is in the closed position. This significantly reduces the so-called sack volume, i.e., the residual volume (RV) of fuel in the space formed by the main bore within the nozzle. Without such a slide valve structure, the residual fuel in the main bore (and nozzle bore) would drip into the combustion chamber after fuel injection has finished, negatively impacting fuel consumption, reliability, and emissions.

[0008] Because the nozzle body protrudes into the combustion chamber, it is exposed to the high-temperature gases of the combustion chamber, and parts of the nozzle body reach very high temperatures (up to approximately 400°C).

[0009] DK181704B1 discloses a fuel valve for injecting liquid fuel into a crosshead-type large two-stroke turbocharged uniflow scavenging internal combustion engine, this fuel valve A fuel valve housing having a shaft, a proximal end and a distal end, A valve needle that is displaceable in the axial direction and has a closed position where it is seated on the valve seat and an open position where it is separated from the valve seat, A spray nozzle is located at the distal end of the vertically elongated fuel valve housing, It is equipped with. The spray nozzle comprises a nozzle body, the nozzle body having a region along the axis from the base of the proximal end of the nozzle body to the closed distal end of the nozzle body, and further the nozzle body, The elongated cylindrical portion between the base and the closed distal end, An inlet for receiving liquid fuel from the fuel valve housing, which opens to the base, Multiple 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, The plurality of straight nozzle holes are connected to the straight main hole by separate supply paths that are positioned obliquely to themselves and the straight main hole. The valve needle has a distal portion having a cylindrical end supported by a shank, the cylindrical end fitting snugly into the main hole as a journal to disconnect the supply passage from the main hole when the valve needle is in the closed position.

[0010] This known design works well with conventional fuels such as fuel oil. However, the movement to reduce or eliminate CO2 emissions is leading to the use of different types of fuel components, such as ammonia. Tests have shown that this conventional design does not work with ammonia or other low-viscosity fuels. This is because the low viscosity of ammonia and the heat transferred from the combustion chamber to the nozzle cause the ammonia trapped above the distal cylindrical section to heat up and boil rapidly, resulting in an insufficient barrier formed by the distal cylindrical section that tightly receives the fuel in the main bore.

[0011] If the barrier is insufficient, pressure will be generated that pushes ammonia beyond the distal cylindrical section into the combustion chamber, even when the fuel valve is closed. Ideally, ammonia should not enter the combustion chamber when the fuel valve is closed. If ammonia enters the combustion chamber when the fuel valve is closed, it will result in incomplete combustion or unburned ammonia flowing into the exhaust system, which is highly undesirable. Summary

[0012] In light of the above, the objective 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 mitigates the above-mentioned problems.

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

[0014] According to the first aspect, a fuel valve is provided for injecting liquid fuel into a crosshead-type large two-stroke turbocharged uniflow scavenging internal combustion engine. This fuel valve is A longitudinally elongated fuel valve housing having a longitudinal axis, a proximal end, and a distal end; A valve needle that is axially displaceable, having a closed position in which it is seated on a valve seat and an open position in which it is separated from the valve seat; A spray nozzle positioned at the distal end of the vertically elongated fuel valve housing; It has, The spray nozzle comprises a nozzle body, the nozzle body having a region along the longitudinal axis from the base of the proximal end of the nozzle body to the closed distal end of the nozzle body, the base being attached to the distal end of the fuel valve housing, The nozzle body is 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, the inlet opening at the base; Multiple nozzle holes and; A main hole having longitudinal depth extending from the inlet into the nozzle body; It has, The valve needle has a cylindrical distal portion supported on the shank, The cylindrical tip portion has an axial shape that fits snugly into the distal portion of the main hole 50 in order to fluidly separate the nozzle hole from the main hole 50 when the valve needle 35 is in the closed position. The cylindrical distal portion is provided with a circumferential groove, and a seal ring is held in the circumferential groove. In the closed position of the valve needle, the main hole has a smooth cylindrical surface facing the seal ring. In the open position of the valve needle, the main hole has a discontinuous cylindrical surface facing the seal ring, and the discontinuity of the discontinuous cylindrical surface is formed by a plurality of axial grooves arranged at intervals in the circumferential direction.

[0015] By providing a seal ring and a circumferential groove that accommodates the seal ring, the fuel valve can be equipped with a seal ring in its cylindrical distal portion to prevent leakage of low-viscosity fuel, while allowing fuel to pass through the seal ring when the valve needle is in the open position, and preventing fuel from leaking into the combustion chamber when the fuel valve is closed. As a result, undesirable emissions are reduced.

[0016] In one example of the implementation of the first aspect described above, the main hole has a first diameter proximal to the axial groove, and a second diameter smaller than the first diameter in the region of the axial groove and in the region forming the smooth cylindrical surface facing the seal ring in the closed position of the valve needle.

[0017] In one example of the implementation of the first aspect described above, the handle portion has a smaller cross-sectional area than the cylindrical distal portion.

[0018] In one example of the implementation of the first aspect described above, when the valve needle is in the closed position, the cylindrical distal portion separates the opening of the nozzle hole from the main hole portion, which is the proximal portion of the cylindrical distal portion.

[0019] In an example of an implementation form of the first aspect, when the valve needle is in the open position, the cylindrical distal portion connects the opening of the nozzle hole to a portion of the main hole that is proximal to the cylindrical distal portion.

[0020] In an example of an implementation form of the first aspect, the axially displaceable valve needle is slidably received within the longitudinal bore of the elongate valve housing. In the closed position, the valve needle seats on the valve seat, which is preferably a conical valve seat. In the open position, the valve needle is unseated from the valve seat. The valve needle is preferably elastically or fluidly biased toward the closed position. Preferably, a fuel chamber that opens into the valve seat surrounds the valve needle.

[0021] In an example of an implementation form of the first aspect, the fuel valve includes a fuel inlet port for connecting to a liquid fuel source in the elongate fuel valve housing.

[0022] In an example of an implementation form of the first aspect, the plurality of nozzle holes are substantially radially oriented.

[0023] In an example of an implementation form of the first aspect, the plurality of nozzle holes each have a nozzle axis, and the nozzle axis of each nozzle hole is disposed at an obtuse angle α with respect to the longitudinal axis X.

[0024] In an example of an implementation form of the first aspect, the radial components of the nozzle axes with respect to the longitudinal axis each have an arc of less than 120 degrees, preferably less than 110 degrees, more preferably less than 100 degrees, and are distributed over a sector of a circle, preferably substantially evenly distributed.

[0025] In an example of an implementation form of the first aspect, the fuel valve has 3 to 12 axial grooves.

[0026] In an example of an implementation form of the first aspect, the circumferential groove holds two or more seal rings.

[0027] In one example of the implementation of the first aspect described above, the seal ring has a joint, preferably a labyrinth-type joint (a joint with a complex shape).

[0028] According to the second aspect, a crosshead-type large two-stroke turbocharged uniflow scavenging internal combustion engine is provided, which is equipped with either a fuel valve or its implementation form according to the first concept.

[0029] These and other aspects will become even clearer through the examples and embodiments described below. [Brief explanation of the drawing]

[0030] The present invention will be described in more detail below with reference to the exemplary embodiments shown in the drawings. [Figure 1] This is a perspective view showing the front and one side of a large two-stroke unit-flow scavenging turbo engine according to an exemplary embodiment. [Figure 2] Figure 1 is a perspective view showing the rear end and the other side of the engine. [Figure 3] Figure 1 shows a diagram illustrating the intake and exhaust systems of the engine. [Figure 4] Figures 1 to 3 are side views of one embodiment of a fuel valve used in the engine. [Figure 5] Figure 4 is a cross-sectional view of the fuel valve. [Figure 6] Figure 4 or Figure 5 is a cross-sectional view of the fuel valve nozzle. [Figure 7] Figure 6 is a perspective view of the nozzle. [Figure 8] Figures 4 and 5 are cross-sectional views of the front of the fuel valve. The nozzle is different from that shown in Figures 6 and 7. [Figure 9] Figure 8 is a cross-sectional view of the nozzle as seen from the direction of the nozzle. It shows vertical recesses that are distributed around the circumference. [Figure 10] Figure 8 is another cross-sectional view of the nozzle, seen from the direction of the nozzle. The sealing ring is shown. [Figure 11]Figure 8 shows another cross-sectional view of the front part of the fuel valve. [Figure 12] Figure 8 shows another cross-sectional view of the front part of the fuel valve. [Figure 14] Figure 8 is a detailed cross-sectional view of the fuel valve nozzle. [Figure 14] This is a perspective view of the distal portion of a valve needle equipped with a sealing ring. [Figure 15] This is a magnified view of the seal ring. [Figure 16] Figure 5 shows the position of the fuel valve nozzle inside the cylinder cover, viewed from the piston side, illustrating the orientation of the nozzle hole and the resulting fuel jet. Detailed description

[0031] The following detailed description illustrates a fuel valve and a large two-stroke engine in which the fuel valve is used, using exemplary embodiments. 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 is a schematic representation of the turbocharged large low-speed two-stroke internal combustion engine, along with its intake and exhaust systems. 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 typically has five to sixteen cylinders arranged in series. These cylinders are supported on an engine frame 24. Such engines can also be used, for example, as the main engine of an ocean-going vessel or as a stationary engine to power a generator in a power plant. The total output of the engine can be, for example, in the range of 5,000 to 110,000 kW.

[0032] The engine can be a two-stroke uniflow diesel engine (compression-ignition engine), with a ring-shaped scavenging port 19 controlled by the piston located in the lower region of the cylinder liner 1, and an exhaust valve positioned in 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 a so-called uniflow type. The scavenging air is guided through the scavenging receiver 2 to the scavenging port 19 of each cylinder. Each cylinder is formed by a cylinder liner 1. A 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 located in the cylinder cover 26. Combustion occurs, and exhaust gas is generated. When the exhaust valve 4 opens, the exhaust gas flows through the exhaust duct 20 connected to the cylinder 1 to the exhaust receiver 3, and further through the first exhaust pipe 18 to the turbine 6 of the turbocharger 5. From there, the exhaust gas is exhausted through the second exhaust pipe 7. The turbine 6 drives the compressor 9 via the shaft 8. Air is supplied to the compressor 9 from the air inlet 10.

[0033] The compressor 9 sends compressed scavenging air to the intake pipe 11 connected to the intake receiver 2. The scavenging air in the intake pipe 11 passes through the intercooler 12 to cool the intake air. The cooled intake air passes through an auxiliary blower 16 driven by an electric motor 17. The auxiliary blower 16 compresses the flow of intake air toward the intake receiver 2 when the engine is under low or partial load. When the engine is under high load, the turbocharger's compressor 9 can supply sufficiently compressed scavenging air, so the auxiliary blower 16 is bypassed by a check valve 15.

[0034] The cylinder is formed within the cylinder liner 1. The cylinder liner 1 is supported by the cylinder frame 25. The cylinder frame 25 is supported by the frame 24.

[0035] Figures 4 to 15 show one embodiment of two or three fuel valves 30 fitted into the through-bore of the cylinder cover 26 of each cylinder. The fuel valve 30 is fitted into the through-bore of the cylinder cover 26 with its rear end 31 protruding from the upper side of the cylinder cover 26 and the distal end (tip) of the nozzle 40 protruding slightly into the combustion chamber. The fuel valve 30 has a vertically elongated fuel valve body 32. The fuel valve body 32 has a nozzle holder at its distal end 33. The nozzle holder connects the nozzle 40 to the vertically elongated fuel valve body 32. Liquid fuel (e.g., ammonia, ethanol, methanol, diesel, heavy oil) is supplied to the combustion chamber 14 through the nozzle 40 by the fuel valve 30. The liquid fuel is supplied to the combustion chamber 14 in a controlled manner and with a timed flow. The fuel valve 30 shown in Figure 4 has a vertically elongated external 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), or the fuel valve 30 may be connected to a fuel pump (not shown) of an internal combustion engine.

[0036] The head at the proximal end 31 has a fuel inlet. The fuel inlet is connected to a duct and flow path that extends through the valve body 32. An axially displaceable valve needle 35 is positioned as a journal within the valve housing 32 and has an open position in which the valve needle 35 is separated from the (preferably conical) valve seat 36 and a closed position in which the valve needle 35 (the portion of which corresponds to the valve seat 36) is seated on the valve seat 36 to close the valve. In this embodiment, the valve needle 35 is elastically biased toward the closed position by an elastic means formed by a helical spring 83. 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, this pressure is caused by acting on the surface of the valve needle 35 or by acting on a piston or plunger connected to the valve needle 35 to actuate the valve needle 35. A fuel chamber 68 is provided surrounding the valve needle 35 and opening to the valve seat 36. The fuel valve 30 has a nozzle 40 mounted on 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.

[0037] In this embodiment, the fuel valve 30 is equipped with an axially movable valve needle 35. The valve needle 35 has a conical portion which cooperates with a conical seat 36 within the elongated housing 32 of the fuel valve 30.

[0038] Figure 16 illustrates how the nozzle 40 is positioned on the edge of the cylinder cover 26. Figure 16 also illustrates the direction of fuel injection. The direction of fuel injection corresponds to the directions of axes I, II, III, IV, and V of the multiple nozzle holes 45 of the nozzle 40. The direction of gas swirling in the combustion chamber is illustrated by a curved dashed arrow 66.

[0039] In some embodiments, the fuel valve 30 includes a booster pump for increasing the pressure of the fuel supplied to the fuel valve 30. The main component of the booster pump is a booster plunger 80.

[0040] Figures 6 to 11 show the distal portions of the nozzle 40 and valve needle 35 in more detail.

[0041] The nozzle 40 has a nozzle body that extends from a base 42 at the proximal end 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, for example, a suitable alloy well known in the art (e.g., tool steel).

[0042] 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. The main hole 50 has a longitudinal depth from the inlet 48 into the nozzle body.

[0043] The closed distal end (tip) 44 has a substantially planar end face 47 having a circular or elliptical outer shape. The end face 47 is connected to the cylindrical portion via a curved or rounded transition surface.

[0044] The nozzle 40 is provided with a plurality of nozzle holes 45. These nozzle holes are preferably linear. The nozzle 40 has any desired number of nozzle holes 45. Preferably, it has 3 to 7 nozzle holes 45, more preferably 3 to 6, and most preferably 5 or 6. The nozzle 40 according to this embodiment has 6 nozzle holes 45.

[0045] Each nozzle hole 45 opens to the outer surface of the nozzle body 43 at a different radial angle, and when the fuel valve 30 opens, it creates a fan-shaped fuel jet in the combustion chamber, as shown in Figure 16. Each nozzle hole 45 opens to the outer surface of the nozzle body 43 at a different radial angle. Preferably, each nozzle hole 45 opens to the cylindrical surface 43 and / or the transition surface.

[0046] Each nozzle hole 45 has nozzle axes I, II, III, IV, and V (Figure 16). The nozzle axes I, II, III, IV, and V of each nozzle hole 45 are positioned at an obtuse angle α with respect to the main spindle X. This obtuse angle α may differ for each nozzle hole 45. The radial components of each nozzle axis I, II, III, IV, and V with respect to the main spindle X are distributed over a sector-shaped arc 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, and V) with respect to the main spindle X are distributed substantially evenly in the arc to maximize the amount of nozzle body material between the individual nozzle holes 45.

[0047] The base portion 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, into the cylindrical portion 43 in a direction along the main axis X, and reaches a position close to the distal end 44 of the nozzle body. The main hole 50 is connected to a plurality of nozzle holes 45.

[0048] 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 may have the same diameter as the main hole.

[0049] The valve needle 35 has a distal portion having a cylindrical distal portion 39. The cylindrical distal portion 39 is preferably supported by a shank portion 38 which has a smaller diameter or cross-sectional area than the cylindrical distal portion 39.

[0050] The cylindrical tip portion 39 has a shaft-like shape that fits snugly into the distal portion of the main hole 50 in order to fluidly separate the nozzle hole 45 from the main hole 50 when the valve needle 35 is in the closed position.

[0051] The cylindrical distal portion 39 is provided with a circumferential groove 54, in which a seal ring 52 is held. The seal ring 52 is made of an alloy suitable for high temperature and high pressure and has a joint portion 53. This piston ring may be coated with a diamond-like carbon (DLC) coating. The main bore 50 has a smooth cylindrical surface that faces the seal ring 52 when the valve needle 35 is in the closed position. The seal ring 52 provides a sealing function to this smooth cylindrical surface, preventing fuel (including low-viscosity fuel) from passing through the cylindrical distal portion 39 and leaking.

[0052] The main bore 50 has a discontinuous cylindrical surface that faces the seal ring 52 when the valve needle 35 is in the open position. The discontinuity in this cylindrical surface is formed by a plurality of axial grooves 63 that are spaced apart in the circumferential direction. In this embodiment, there are six axial grooves, but the number of axial grooves 63 can range from a minimum of three to a maximum of twelve. This discontinuous cylindrical surface allows fuel to pass through the axial grooves 63 to the seal ring 52 while holding the seal ring 52 in a compressed state within the circumferential grooves 54. Holding the seal ring 52 in a compressed state is advantageous because otherwise, the seal ring 52 or the sliding surface on which the seal ring 52 slides would be damaged when the valve needle 35 moves between the open and closed positions.

[0053] When the valve needle 35 is in the closed position, the cylindrical distal portion 39, equipped with a seal ring 52, fluidly isolates the nozzle hole 45 from the main hole 50. Therefore, when the valve needle 35 is in the closed position, 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.

[0054] The cylindrical distal portion 39 allows fuel to flow to the nozzle hole through the axial groove 63 when the valve needle 35 is in the open position.

[0055] The main bore 50 has a first diameter proximal to the axial groove 63, and a second diameter smaller than the first diameter in the region of the axial groove 63 and in the region that forms a smooth cylindrical surface facing the seal ring 52 when the valve needle 35 is in the closed position.

[0056] An axially displaceable valve needle 35 is slidably received within a longitudinal bore 64 in the valve housing 32. The valve needle 35 seats on the valve seat 36 (preferably a conical valve seat) in the closed position and separates from the valve seat 36 in the open position. The fuel chamber 68 surrounds the valve needle 35 and opens to the valve seat 36. One or more conduits 61 supply fuel to the fuel chamber 68. A sealant conduit 65 supplies pressurized sealant at a pressure higher than the fuel pressure into the hole into which the valve needle 35 is fitted.

[0057] The multiple nozzle holes 45 are substantially oriented radially.

[0058] In some embodiments, the circumferential groove 54 holds two or more seal rings 52 in order to enhance the sealing ability.

[0059] In some embodiments, the joint 53 is labyrinth-shaped (i.e., a joint with a complex shape) in order to enhance the sealing ability.

[0060] The present invention has been described using various embodiments. However, by examining the specification, drawings, and claims of this application, a person skilled in the art will understand and be able to implement many variations in the invention described in the claims, in addition to the embodiments described. The words “equipment,” “having,” and “including” in the claims do not exclude the existence of elements or steps that are not described. The absence of explicit indication that there are multiple elements in the claims does not exclude the existence of multiple such elements. The presence of several matters in separate dependent claims does not exclude the possibility of combining and implementing them, and such combinations may be beneficial. The reference numerals used in the claims should not be interpreted 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 scavenging internal combustion engine, A longitudinally elongated fuel valve housing having a longitudinal axis, a proximal end, and a distal end; A valve needle that is axially displaceable, having a closed position in which it sits on a valve seat and an open position in which it is separated from the valve seat; A spray nozzle positioned at the distal end of the vertically elongated fuel valve housing; It has, The spray nozzle comprises a nozzle body, the nozzle body having a region along the longitudinal axis from the base of the proximal end of the nozzle body to the closed distal end of the nozzle body, the base being attached to the distal end of the fuel valve housing, The nozzle body is The elongated (preferably cylindrical) portion between the base and the closed distal end; An inlet for receiving liquid fuel from the fuel valve housing, the inlet opening at the base; Multiple nozzle holes; A main hole having longitudinal depth extending from the inlet into the nozzle body; It has, The valve needle has a cylindrical distal portion supported on the shank, The cylindrical tip portion has an axial shape that fits snugly into the distal portion of the main hole in order to fluidly separate the nozzle hole from the main hole when the valve needle is in the closed position. The cylindrical distal portion is provided with a circumferential groove, and a seal ring is held in the circumferential groove. In the closed position of the valve needle, the main hole has a smooth cylindrical surface facing the seal ring. In the open position of the valve needle, the main hole has a discontinuous cylindrical surface facing the seal ring, and the discontinuity of the discontinuous cylindrical surface is formed by a plurality of axial grooves arranged at intervals in the circumferential direction. Fuel valve.

2. The fuel valve according to claim 1, wherein the main bore has a first diameter proximal to the axial groove, and has a second diameter smaller than the first diameter in the region of the axial groove and in the region forming the smooth cylindrical surface facing the seal ring when the valve needle is closed.

3. The fuel valve according to claim 1, wherein the shank portion has a smaller cross-sectional area than the cylindrical distal portion.

4. The fuel valve according to claim 1, wherein when the valve needle is in the closed position, the cylindrical distal portion separates the opening of the nozzle hole from the portion of the main hole that is on the proximal side of the cylindrical distal portion.

5. The fuel valve according to claim 1, wherein when the valve needle is in the open position, the cylindrical distal portion connects the opening of the nozzle hole to the portion of the main hole that is on the proximal side of the cylindrical distal portion.

6. The valve needle is - It is slidably received within the longitudinal bore of the vertically elongated fuel valve housing; - In the closed position, it sits on the valve seat, and in the open position, it moves away from the valve seat; - It is elastically or fluidly biased toward the closed position; The fuel valve according to claim 1.

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

8. The fuel valve according to claim 1, wherein the plurality of nozzle holes are substantially oriented radially.

9. The fuel valve according to claim 1, wherein each of the plurality of nozzle holes has a nozzle axis, and the nozzle axis of each nozzle hole is arranged at an obtuse angle α with respect to the longitudinal axis.

10. The fuel valve according to claim 9, wherein the radial component of each of the nozzle shafts with respect to the longitudinal axis is distributed on a sector-shaped area having an arc of less than 120 degrees.

11. The fuel valve according to claim 1, having three to twelve axial grooves.

12. The fuel valve according to claim 1, wherein the circumferential groove holds two or more seal rings.

13. The fuel valve according to claim 1, wherein the seal ring has a gap or a labyrinth-type gap.

14. A crosshead type large two-stroke turbocharged uniflow scavenging internal combustion engine comprising a fuel valve according to any one of claims 1 to 13.

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