Fuel valve for injecting fuel into cylinders of large turbocharged two-stroke uniflow scavenged internal combustion engine, and engine with such 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 in this application (hereinafter referred to as the present disclosure) relates to a fuel valve for injecting liquid fuel into a cylinder of a large turbocharged two-stroke uniflow scavenging internal combustion engine.

[0002] Large turbocharged two-stroke uniflow scavenging crosshead internal combustion engines are typically used as prime movers in large ocean-going ships such as container ships and in power plants.

[0003] This type of engine has a single exhaust valve in the center of the cylinder cover, i.e. the top of the cylinder, and a ring of piston-controlled scavenging ports in 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 at an angle. This is to create a swirl of the gas in the combustion chamber.

[0004] The cylinder cover has two or three fuel valves arranged around a centrally located exhaust valve. The nozzles of the fuel valves project into the combustion chamber. The fuel valves are located on the periphery of the cylinder cover, i.e. not in the center. The nozzle holes are aligned in the direction of the swirl into the combustion chamber, away from the cylinder wall. Sometimes one nozzle hole is oriented against the swirl in the combustion chamber.

[0005] The nozzle is attached to the front end (distal end) of the fuel valve. The fuel valve has an elongated housing that passes through the cylinder cover, with the rear end (proximal end) protruding from the top surface of the cylinder cover and the nozzle at the front end (distal end) protruding into the combustion chamber.

[0006] Known nozzles for large two-stroke diesel engines of the crosshead type typically have an elongated body. The nozzle body has a cylindrical section with a straight main bore. This main bore leads from the base end of the nozzle at the proximal end of the nozzle body to a nozzle hole located near 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 point downwards with respect to the piston (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 oriented transversely to the main axis of the nozzle / fuel valve, typically at approximately right angles to the main axis of the engine cylinder. Typically, each nozzle has 3 to 7 nozzle holes, all 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 front part of the valve needle consists of a distal cylinder that is received snugly in the main bore and acts as a slide valve to close the nozzle bore when the valve needle is in the closed position, thereby significantly reducing the so-called sac volume, i.e. the residual volume (RV) of fuel in the space formed by the main bore in the nozzle. Without such a slide valve structure, the residual amount of fuel in the main bore (and in the nozzle bore) would drip into the combustion chamber after the fuel injection is terminated, which would have a negative impact on fuel consumption, reliability and emissions.

[0008] Because the nozzle body protrudes into the combustion chamber, it is exposed to the hot gases in the combustion chamber and parts of the nozzle body reach relatively high temperatures of up to about 400°C. In an engine running on heavy fuel oil, the temperature of the incoming fuel is about 140°C. This means that the incoming fuel in the main bore leaving the nozzle through the nozzle holes has a significantly lower temperature than the gas surrounding the outer surface of the nozzle body. The nozzle body material is therefore exposed to significant temperature gradients, which creates stresses in the nozzle material.

[0009] Therefore, the nozzle is at risk of cracks occurring in the nozzle region where the nozzle holes are located, particularly between the nozzle holes, due to thermal fatigue of the material when exposed to gases with high operating temperatures in the combustion chamber and the strong cooling effect of the injected fuel.

[0010] This problem cannot be solved by simply increasing the spacing between the nozzle holes, increasing the material between them, and decreasing the temperature gradient, because increasing the diameter of the nozzle is highly undesirable, since it would likely increase the amount of heat transferred from the combustion chamber to the nozzle. In addition, it is not possible to simply increase the radial spacing of the nozzle holes, since two or three fuel valves are arranged on the periphery of the cylinder cover, limiting the radial spread of the nozzle holes to an angle of about 110°. This is especially true when there is a slide valve in the nozzle, which requires that the main hole in the nozzle has a certain diameter, which results in a limit to the wall thickness of the nozzle body. Furthermore, fuel valves with a slider in the nozzle body require that the nozzle holes, when injecting fuel at the same time, 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 system. The nozzle assembly comprises a closed nozzle valve element and an injection rate shaping control device having an injection spill circuit for venting a portion of the injected fuel to produce a predetermined change in the flow rate of fuel injected into the combustion chamber. The spill circuit includes a spill passage integrally formed in the nozzle valve element. The injection rate shaping control device may have a spill acceleration chamber formed in the nozzle valve element for producing a sudden increase in the spill flow rate. A spill circuit purge device is also provided for removing fuel from the outflow circuit and the acceleration chamber during each injection event, thereby ensuring an unhindered and effective flow of spilled fuel during the next spill event. The purge device includes a purge passage sized and formed to restrict the flow of purge gas to ensure sufficient fuel removal from the injection spill circuit while avoiding excessive purge gas flow. The purge passage may comprise an annular clearance gap formed between the nozzle valve element and the nozzle housing wall, or may comprise an orifice passage formed in an inner portion of the nozzle valve element.

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

[0013] These and other objects are achieved by the features of the independent claims. Further detailed implementations will become apparent from the dependent claims, the description 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 scavenged internal combustion engine. The fuel valve includes: an 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 unseated from the valve seat; a nozzle disposed at a distal end of the elongated fuel valve housing; the nozzle comprises a nozzle body having an area along the longitudinal axis from a base at a proximal end of the nozzle body to a closed distal end of the nozzle body, the base being attached to the fuel valve housing, the nozzle body comprising: an elongated (preferably cylindrical) section between the base and the closed distal end; an inlet for receiving liquid fuel from the fuel valve housing, the inlet opening into the base; a plurality of straight nozzle holes each opening into an outer surface of the nozzle body at a different radial angle; a single straight main bore extending longitudinally from said inlet into said nozzle body; Equipped with at least two of the plurality of straight nozzle holes are connected to the main hole by respective individual supply passages, the individual supply passages being disposed obliquely with respect to the nozzle hole and the main hole to which the individual supply passages are connected; The valve needle has a distal portion having a cylindrical end supported on a stem, the cylindrical end being a slidable fit within the main bore so as to fluidly isolate the supply passage from the main bore when the valve needle is in the closed position.

[0015] Providing separate feed passages at an angle to the straight nozzle holes and the main nozzle bore provides a high degree of freedom in selecting the angle of the straight nozzle holes relative to the main axis and their location in the nozzle body material, thereby making it possible to select a nozzle hole location and orientation that provides more nozzle body material between adjacent nozzle holes so as to reduce the thermal coefficient and the formation of cracks related to thermal stresses, without increasing the overall size of the nozzle, and in particular the diameter of the cylindrical portion of the nozzle.

[0016] In one implementation of the first perspective, the individual supply passages are oriented away from the longitudinal axis at a first angle relative to the longitudinal axis from where they connect to the main bore, such that the "bases" of the nozzle holes are located further radially outward, thereby resulting in a greater distance between adjacent nozzle holes and therefore more nozzle body material between adjacent nozzle holes. In this context, the "base" is located where the straight nozzle holes connect to the individual supply passages.

[0017] In one implementation of the first perspective, the straight nozzle holes are oriented away from the longitudinal axis X at a second angle relative to the longitudinal axis X, when viewed from where the nozzle holes connect to the individual supply passages, where the second angle is greater than the first angle.

[0018] In one example implementation of the first approach, the individual supply passages are straight holes, preferably with rounded or rounded ends to reduce stress in the nozzle hole material.

[0019] In one example implementation of the first perspective, the cylindrical end fluidly connects the separate supply passages to the straight main bore when the valve needle is in an open position.

[0020] In one example implementation of the first perspective, the cylindrical end covers the openings of the individual supply passages to the straight main bore when the valve needle is in a closed position.

[0021] In one example implementation of the first perspective, when the valve needle is in an open position, the cylindrical end does not cover the openings of the individual supply passages to the straight main bore.

[0022] In one example implementation of the first approach, the individual supply passages open into the main bore at a predetermined axial distance from the inlet, and the cylindrical end reaches a position beyond the predetermined axial distance when the valve needle is in a closed position.

[0023] In one implementation of the first aspect, an axially displaceable valve needle is slidably received within a longitudinal bore of an elongated valve housing. In a closed position, the valve needle seats on a valve seat. The valve seat is preferably a conical valve seat. In an open position, the valve needle lifts from the valve seat. The valve needle is preferably biased towards the closed position. A fuel chamber is preferably provided surrounding the valve needle and opening to the valve seat.

[0024] In one implementation of the first aspect, the fuel valve includes a fuel inlet port in the elongated fuel valve housing for connection to a liquid fuel source.

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

[0026] In one example implementation of the first approach, the straight nozzle holes all have the same diameter, and preferably the individual supply passages have diameters larger than the diameters of the straight nozzle holes.

[0027] In one implementation of the first aspect, the straight main bore is formed in a bushing that is a tight fit into a bore in a valve body.

[0028] In one implementation of the first approach, the cylindrical end is hollow to form a fluid passageway that preferably opens proximally to an exterior of the stem and axially distally.

[0029] In one example of an implementation of the first aspect, the plurality of straight nozzle holes each open into a cylindrical surface.

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

[0031] In one example implementation of the first approach, the straight nozzle holes open into a cylindrical surface and / or into the transition surface.

[0032] In one example implementation of the first approach, the plurality of straight nozzle holes have respective 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 implementation of the first approach, the radial components of each of the nozzle axes I, II, III, IV, V relative to the main axis X are distributed over a sector having an arc of less than 120 degrees, preferably less than 110 degrees, and more preferably less than 100 degrees, and preferably substantially evenly distributed.

[0034] In one example implementation of the first approach, at least three of the plurality of straight nozzle holes are connected to the straight main hole by individual supply paths arranged obliquely relative to the nozzle holes and the straight main hole.

[0035] According to a second aspect, there is provided a crosshead type large two-stroke turbocharged uniflow scavenging internal combustion engine equipped with a fuel valve according to the first aspect or any of its implementations.

[0036] These and other aspects of the present invention will be apparent from and elucidated with reference to the examples described below. [Brief description of the drawings]

[0037] The invention will now be explained in more detail with reference to exemplary embodiments shown in the drawings. [Figure 1] FIG. 1 is a perspective view of a front and one side of a large two-stroke unit-flow scavenging turbomachine according to an exemplary embodiment. [Diagram 2] FIG. 2 is a perspective view showing the aft end and the other side of the engine of FIG. 1. [Diagram 3] This is a diagram of the intake and exhaust systems of the engine in Figure 1. [Figure 4] FIG. 4 is a cross-sectional view of one embodiment of a fuel valve for use in the engine of FIGS. 1 to 3. [Diagram 5] FIG. 4 is a cross-sectional view showing another embodiment of a fuel valve for use in the engine of FIGS. 1 to 3. [Figure 6] FIG. 6 is a perspective view of a nozzle of the fuel valve of FIG. 4 or FIG. 5. [Figure 7] FIG. 7 is a cross-sectional view of the nozzle of FIG. [Figure 8] 7 is a cross-sectional view of the tip of the nozzle of FIG. 6 with the barrel at the distal end of the valve needle in an open position. [Figure 9] This is also a cross-sectional view of the nozzle tip of FIG. 6, but with the barrel at the distal end of the valve needle in a closed position. [Figure 10] 7 is a transparent image of the nozzle tip of FIG. 6. [Figure 11] FIGURE 7 is another cross-sectional view of the nozzle tip of FIGURE 6, in which the barrel at the distal end of the valve needle is in a closed position. [Figure 12] FIG. 6 is a view from the piston side of the nozzle location of the fuel valve of FIG. 5 in the cylinder cover, showing the nozzle hole orientation and the resulting fuel jet. Detailed explanation

[0038] In the following detailed description, the fuel valve and a large two-stroke engine in which it is used are described according to an exemplary embodiment. Figures 1 to 3 depict a turbocharged large slow-speed two-stroke internal combustion engine. The engine has a crankshaft 22 and a crosshead 23. Figure 3 is a schematic representation of a turbocharged large slow-speed two-stroke internal combustion engine together with its intake and exhaust systems. In this exemplary embodiment, the engine has six cylinders in series. Each cylinder is formed by a cylinder liner 1. A turbocharged large two-stroke internal combustion engine typically has 5 to 16 cylinders arranged in series. The cylinders are supported by an engine frame 24. Such an engine can also 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 power output of the engine can be, for example, in the range of 5000 to 110000 kW.

[0039] The engine can be a two-stroke uniflow diesel engine (compression ignition engine), in which the lower region of the cylinder liner 1 is provided with a ring-shaped scavenging port 19, which is a port controlled by a piston, and the cylinder liner 1 has an exhaust valve at the top center. For this reason, the flow in the combustion chamber is always from bottom to top, and the engine is of the so-called uniflow type. The scavenging air is led through a scavenging receiver 2 to the scavenging ports 19 of each cylinder, each of which 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 nozzles of two or three fuel valves 30 arranged in a cylinder cover 26. Combustion occurs and exhaust gases are produced. When the exhaust valve 4 opens, the exhaust gases flow through an exhaust duct 20 connected to the cylinder 1 to the exhaust receiver 3, and then through a first exhaust pipe 18 to a turbine 6 of a turbocharger 5. From there, the exhaust gases are exhausted through a second exhaust pipe 7. The turbine 6 drives a compressor 9 via a shaft 8. The compressor 9 is supplied with air through an air inlet 10 .

[0040] The compressor 9 delivers compressed scavenging air to the charge air pipe 11 which leads to the charge air receiver 2. The scavenging air in the scavenging pipe 11 passes through an intercooler 12 for cooling the charge air. The cooled charge air passes through an auxiliary blower 16 driven by an electric motor 17. The auxiliary blower 16 compresses the charge air flow towards the charge air receiver 2 when the engine is at low or partial load. When the engine is at high load, the turbocharger compressor 9 can provide enough compressed scavenging air and the auxiliary blower 16 is bypassed by a check valve 15.

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

[0042] FIG. 4 shows an embodiment of one of two or three fuel valves 30 mounted in a through bore of the cylinder cover 26 of each cylinder. The fuel valves 30 are mounted in the through bore of the cylinder cover 26 with a rear end 31 protruding from the top side of the cylinder cover 26 and a distal end (tip) of a nozzle 40 protruding slightly into the combustion chamber. The fuel valves 30 have an elongated 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 elongated fuel valve body 32. Liquid fuel (e.g., ethanol, methanol, diesel, heavy fuel oil) is delivered by the fuel valves 30 through the nozzle 40 to the combustion chamber 14. The liquid fuel is delivered to the combustion chamber 14 in a controlled and timed manner. The fuel valve 30 shown in FIG. 4 has an elongated outer housing 32. The housing 32 has a head at its proximal end 31 by which the fuel valve 30 may be mounted to the cylinder cover 26 (in a known manner) and by which the fuel valve 30 may 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 which is in fluid communication with a duct extending through the valve body 32. An axially displaceable valve needle 35 is slidably arranged in the valve housing 32 and has an open position in which the valve needle 35 is free from a (preferably conical) valve seat 36 and a closed position in which the valve needle 35 (a part of the valve needle 35 corresponding to the valve seat 36) is seated on the valve seat 36 to close the valve. The valve needle is elastically biased towards the closed position by elastic means formed in this embodiment by a helical spring 83. The lift of the valve needle 35 against the force exerted by the helical spring 83 is caused by the pressure of the fuel supplied to the fuel valve 30. In particular, this pressure is caused by acting on a surface of the valve needle 35 or on a piston or plunger connected to the valve needle 35 so as to actuate the valve needle 35. A fuel chamber 68 is provided surrounding the valve needle 35 and opening into the valve seat 36. 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 mounted in 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 36 in the elongated housing 32 of the fuel valve 30.

[0045] Figure 12 shows how the nozzles 40 are arranged on the periphery of the cylinder cover 26. Figure 12 also shows the direction of fuel injection, which corresponds to the directions of the axes I, II, III, IV, V of the straight nozzle holes 45 of the nozzle 40. The swirl direction of the gases in the combustion chamber is shown by the curved dashed arrows 66.

[0046] 5 shows another embodiment of the fuel valve 30. This embodiment is similar to the embodiment of FIG. 4, except that it includes a booster pump that boosts the pressure of the fuel supplied to the fuel valve 30. The main component of the booster pump is a booster plunger 80. Other components of the fuel valve 30 according to this embodiment and the nozzle 40 are conceptually identical to the fuel valve of FIG. 4.

[0047] 6 to 11 show the nozzle 40 and the distal portion of the valve needle 35 in greater detail.

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

[0049] An inlet 48 opens into the base 42 for receiving liquid fuel from the fuel valve 30 when the valve needle 35 is in an 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 in a bushing 51 which is tightly fitted, for example by shrink fitting, within a bore 51 in the valve body. However, in some embodiments, the nozzle body is made from a single piece and the nozzle is constructed without the bushing 51.

[0050] The closed distal end (tip) 44 has a substantially planar end surface 47 having a circular or elliptical profile. The end surface 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 has any desired number of nozzle holes 45. Preferably, the nozzle 40 has three to seven nozzle holes 45, more preferably three to six nozzle holes 45, and most preferably five or six nozzle holes 45. The nozzle 40 according to this embodiment has five nozzle holes 45.

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

[0053] The nozzle holes 45 have nozzle axes I, II, III, IV, V (FIG. 10). The nozzle axis I, II, III, IV, V of each nozzle hole 45 is disposed at an obtuse angle α with respect to the main axis X. This obtuse angle α may vary from nozzle hole 45 to 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 sector having an arc of less than 120 degrees, preferably less than 110 degrees, 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 has an inlet port 48 for receiving fuel from the fuel valve 30. A main bore 50 extends from the inlet port 48 into the nozzle body in a direction along the main axis X into the cylindrical portion 43 until it reaches a position near the distal end 44 of the nozzle body. The main bore 50 connects to a number of individual supply passages 49, each of which leads to a nozzle hole 45. Each individual supply passage 49 is disposed at an angle to the axis of the straight main bore 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 separate feed passages 49 to connect each nozzle hole 45 to the main bore 50, the nozzle holes 45 can be arranged to maximize the amount of nozzle body material between them, and the axes I, II, III, IV, V of the nozzle holes 45 can be arranged so that the fuel jet covers a desired circular sector.

[0057] In some embodiments, the inlet port 48 is defined 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] The nozzle holes 45 in the nozzle 40 are widely spaced, resulting in more nozzle material between the nozzle holes 45 and improved resistance to crack formation. The nozzle 40 provides uniform inlet conditions to each nozzle hole 45 to produce a substantially uniform fuel jet.

[0059] The valve needle 35 has a distal portion having a cylindrical end 39 carried by the stem 38. The cylindrical end 39 is a slidable fit within the straight main bore 50 and covers the opening from the individual supply passage 49 to the main bore 50 when the valve needle 35 is in the closed position, as shown in Figures 7, 9 and 11. Thus, when the valve needle 35 is in the closed position, the cylindrical end 39 isolates the individual supply passage 49 from the main bore 50. Thus, fuel in the space between the valve seat 36 and the distal end of the main bore 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 passageway 71 for fuel from the proximal side of the cylindrical end 39 to the distal side of the cylindrical end 39. The fluid passageway 71 opens proximally to the exterior of the stem 38 and opens distally in the axial direction.

[0061] The cylindrical end 39 does not cover the openings from the individual supply passages 49 to the main bore 50 when the valve needle 35 is in the open position, as shown in Figure 8. Thus, the cylindrical end 39 fluidly connects each individual supply passage 49 to the main bore 50 when the valve needle 35 is in the open position.

[0062] Each individual supply passage 49 opens into the main bore a predetermined axial distance from the inlet 48. In the closed position of the valve needle 35, the cylindrical end 39 extends beyond the predetermined axial distance to prevent the flow of fuel to each individual supply passage 49.

[0063] In some embodiments, the individual feed passages 49 are oriented at a first angle relative to the longitudinal axis X in a direction away from the longitudinal axis X from where they connect to the main bore 50, such that the "base" of the nozzle holes 45 is located further radially outward, thereby providing a greater distance between adjacent straight nozzle holes 45 and therefore more nozzle body material between adjacent straight nozzle holes 45. In this context, the "base" location is the location where the straight nozzle holes 45 connect to the individual feed passages 49.

[0064] In some embodiments, the straight nozzle holes 45 are oriented away from the longitudinal axis X at a second angle relative to the longitudinal axis X, as viewed from the location where the nozzle holes 45 connect to the individual supply channels 49, where the second angle is greater than the first angle.

[0065] In one example of an implementation of the first approach, the individual supply passages 49 are straight holes, preferably with rounded or rounded ends (at or near the "base") to reduce stress on the nozzle hole material.

[0066] The present invention has been described using various examples. However, upon review of the specification, drawings, and claims of this application, those skilled in the art will understand and be able to embody many variations in addition to the described embodiments in carrying out the claimed invention. The words "comprise", "have", and "include" in the claims do not exclude the presence of elements or steps not described. Even if the number of elements described in the claims is not explicitly stated as being plural, the presence of the elements in plural is not excluded. Even if several items are described in separate dependent claims, this does not exclude them from being implemented in combination, and they may be implemented in combination to obtain benefits. The signs 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, comprising: an 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 unseated from the valve seat; a spray nozzle disposed at a distal end of the elongated fuel valve housing; the spray nozzle comprises a nozzle body having an area along the longitudinal axis from a base at a proximal end of the nozzle body to a closed distal end of the nozzle body, the base being attached to the fuel valve housing; The nozzle body includes: an elongated portion between the base and the closed distal end; an inlet for receiving liquid fuel from the fuel valve housing, the inlet opening into the base; a plurality of straight nozzle holes each opening into an outer surface of the nozzle body at a different radial angle; a single straight main bore extending longitudinally from said inlet into said nozzle body; Equipped with At least three of the plurality of straight nozzle holes are connected to the straight main hole by respective supply passages disposed obliquely relative to the nozzle holes and the straight main hole; the valve needle has a distal portion having a cylindrical end supported on a stem, the cylindrical end slidably fitting within the main bore to fluidly isolate the separate supply passages from the main bore when the valve needle is in the closed position; Fuel valve.

2. 2. The fuel valve of claim 1, wherein the cylindrical end fluidly connects the separate supply passages to the main straight bore when the valve needle is in an open position.

3. 2. The fuel valve of claim 1, wherein the cylindrical end covers the openings of the individual supply passages to the straight main bore when the valve needle is in a closed position.

4. 3. The fuel valve of claim 2, wherein the cylindrical end does not cover the openings of the individual supply passages to the straight main bore when the valve needle is in an open position.

5. 2. The fuel valve of claim 1, wherein the individual supply passages open into the main bore a predetermined axial distance from the inlet, and the cylindrical end extends beyond the predetermined axial distance in a closed position of the valve needle.

6. 2. The fuel valve of claim 1, wherein the valve needle is slidably received within a longitudinal bore of the elongated fuel valve housing, the valve needle seating on a valve seat in the closed position and unseating from the valve seat in the open position.

7. 10. The fuel valve of claim 1, wherein said elongated fuel valve housing includes a fuel inlet port for connection to a source of liquid fuel.

8. The fuel valve of claim 1 , wherein the plurality of straight nozzle holes all have an equal cross-sectional area or diameter.

9. 2. The fuel valve of claim 1, wherein said straight main hole is formed in a bushing, said bushing being a tight fit in said nozzle body bore.

10. 2. The fuel valve of claim 1, wherein the cylindrical end is hollow to form a fluid passageway.

11. 2. The fuel valve of claim 1, wherein all of said plurality of straight nozzle holes open into a surface of said cylindrical end.

12. 2. The fuel valve of claim 1, further comprising a rounded transition between the cylindrical end surface and a flat distal end face of the nozzle body.

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

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

15. 15. The fuel valve of claim 14, wherein a radial component of the nozzle axis of each of the plurality of straight nozzle holes relative to the longitudinal axis is distributed over a sector having an arc of less than 120 degrees.

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

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