CN118686723B

CN118686723B - Fuel valve and engine having the fuel valve

Info

Publication number: CN118686723B
Application number: CN202410333258.7A
Authority: CN
Inventors: 彼得·哈根
Original assignee: Mannone Solutions Mannone Solutions Germany Branch
Current assignee: Mannone Solutions Mannone Solutions Germany Branch
Priority date: 2023-03-24
Filing date: 2024-03-22
Publication date: 2025-11-18
Anticipated expiration: 2044-03-22
Also published as: CN118686723A; KR20240143900A; JP7717311B2; EP4435250A1; DK181704B1; JP2024137864A; DK202370148A1; KR102883669B1; EP4435250C0; EP4435250B1

Abstract

A fuel valve for injecting fuel into a large two-stroke turbocharged single-flow scavenging internal combustion engine, the fuel valve comprising: a fuel valve housing having an axis, a proximal end, and a distal end; an axially displaceable valve needle having a closed position and an open position; and an atomizer nozzle disposed at the distal end of the elongated valve housing, the atomizer nozzle having a nozzle body comprising: a generally cylindrical portion; an inlet; a plurality of straight nozzle orifices; and a single straight main orifice extending longitudinally from the inlet into the nozzle body, the single straight main orifice being connected to the straight main orifice via a separate supply channel arranged at an angle to the straight main orifice and the associated straight nozzle orifice. This application also provides a large two-stroke turbocharged single-flow scavenging internal combustion engine with a crosshead, including the fuel valve.

Description

Fuel valve and engine with same

Technical Field

The present disclosure relates to a fuel valve for injecting liquid fuel into a cylinder of a large turbocharged two-stroke uniflow scavenged internal combustion engine.

Background

Large turbocharged two-stroke uniflow scavenged cross-head internal combustion engines are commonly used as prime movers for large ocean-going vessels such as container ships or power plants.

The cylinders of these engines are provided with a single exhaust valve, which is arranged centrally in the cylinder head, i.e. at the top of the cylinder, and the cylinder is provided with a ring of piston-controlled scavenging ports at the lower region of the cylinder liner. Thus, the direction of gas delivery through the cylinder is always from bottom to top, and is therefore referred to as uniflow scavenging. The scavenging ports are inclined to generate a swirl in the gas in the combustion chamber.

Two or three fuel valves are arranged in the cylinder head around the centrally placed exhaust valve, the nozzles of the fuel valves protruding into the combustion chamber. The fuel valve is arranged peripherally (i.e. not centrally) in the cylinder head, wherein the nozzle bores of the nozzles are directed substantially with swirl, away from the cylinder wall and into the combustion chamber. Sometimes, individual nozzle holes of the nozzle may resist swirl in the combustion chamber.

The nozzle is attached to the front or distal end of the fuel valve. The fuel valve includes an elongated housing, a proximal or rear end portion of which protrudes from an upper surface of the cylinder head, and an elongated fuel valve housing extending through the cylinder head, and a nozzle located at a front or distal end portion of the elongated fuel valve housing so as to protrude into the combustion chamber.

Known nozzles for large two-stroke diesel engines of the crosshead type generally have an elongated nozzle body comprising a cylindrical portion with a straight main bore leading from the base of the nozzle at the proximal end of the nozzle body to a nozzle bore at or near the distal end of the nozzle body. The tip or distal portion may be rounded or flat, but closed because the nozzle bore must not be directed downward toward the piston (when the piston is at top dead center, i.e., at the fuel injection time of a compression ignition engine, the upper surface of the piston is very close to the tip of the nozzle). Thus, the nozzle bores are oriented primarily laterally with respect to the main axis of the nozzle/fuel valve and are generally at a substantially right angle to the main axis of the engine cylinder. Typically, each nozzle is provided with three to seven nozzle holes, all connected to the main hole.

Generally, known fuel valves for injecting liquid fuel are provided with axially displaceable valve needles that cooperate with conical valve seats to control the flow of fuel to the nozzle. Furthermore, the front part of the valve needle comprises a distal cylinder which is tightly received in the main bore and acts as a sliding valve for closing the nozzle bore when the valve needle is in the closed position, thereby significantly reducing the so-called needle pressure chamber volume, i.e. the residual volume of fuel in the space formed by the main bore in the nozzle. Without such a sliding valve arrangement, the amount of residual fuel in the main bore (and in the nozzle bore) would drip into the combustion chamber after the fuel injection event is completed, which has an adverse effect on fuel consumption, reliability and emissions.

Since the nozzle body protrudes into the combustion chamber, the nozzle body is exposed to the hot gases of the combustion chamber, and portions of the nozzle body will therefore reach relatively high temperatures of up to about 400 ℃. The incoming fuel is suitable for heavy oil operated engines at a temperature of about 140 ℃. Thus, the temperature of the incoming fuel exiting the nozzle through the nozzle hole in the main bore is significantly lower than the temperature of the gas surrounding the outer surface of the nozzle body. As a result, the material of the nozzle body is exposed to a significant temperature gradient, resulting in stresses in the material of the nozzle.

Thus, when the nozzle is exposed to the better cooling effect of the higher operating temperature gases in the combustion chamber and the injected fuel, there is a risk of cracks developing in the areas of the nozzle where the nozzle holes are located, in particular between the nozzle holes, due to thermal fatigue of the material.

This problem cannot be solved by simply increasing the distance between the nozzle holes so that there is more material between the nozzle holes and thus a reduced temperature gradient, as increasing the diameter of the nozzle is highly undesirable, which may increase the heat transferred from the combustion chamber to the nozzle, and by simply increasing the radial spacing between the nozzle holes, as the radial distribution of the nozzle holes is limited to an angle of about 110 ° due to the positioning of two or three fuel valves in the cylinder head on the periphery. This is especially true when a sliding valve is present in the nozzle, requiring the main bore in the nozzle to have a certain diameter, thereby limiting the wall thickness of the nozzle body. Furthermore, in a fuel valve having a slider in a nozzle body, if the nozzle holes are to be simultaneously injected with fuel, it is required that the nozzle holes are opened at substantially the same axial distance from the base of the nozzle to the main hole.

US5765755A discloses an injection rate shaping nozzle assembly for a fuel injector, the assembly comprising a closed nozzle valve element and rate shaping control means comprising means for spilling a portion of fuel to be injected to produce a predetermined time-varying change in the rate of fuel injected into the combustion chamber. The spill circuit includes a spill passageway integrally formed in the nozzle valve member. The rate shaping control device may include an overflow acceleration chamber formed in the nozzle valve element for creating a rapid increase in overflow flow rate. Overflow circuit purging means are provided to remove fuel from the overflow circuit and acceleration chamber between each injection event, thereby ensuring a clear, efficient overflow fuel flow during the next overflow event. The purge means includes a purge passage formed of a predetermined size for restricting the flow of purge gas to ensure adequate removal of fuel from the injection spill circuit while avoiding excessive purge gas flow. The purge channel may comprise an annular gap formed between the nozzle valve element and the nozzle housing wall, or alternatively, the purge channel may comprise an orifice channel formed in an interior portion of the nozzle valve element.

Disclosure of Invention

In view of the foregoing, 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 that overcomes or at least reduces the above-mentioned problems.

The above and other objects are achieved by a fuel valve and an engine according to embodiments of the present application. Further implementations are apparent from the description and the drawings.

According to a first aspect, there is provided a fuel valve for injecting liquid fuel into a large two-stroke turbocharged uniflow scavenged internal combustion engine having a crosshead, the fuel valve 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 in which the valve needle rests on the valve seat and an open position in which the valve needle is lifted from the valve seat, and

A nozzle arranged at a distal end portion of the elongated valve housing,

The nozzle has a nozzle body extending along a 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 a fuel valve (30),

The nozzle body comprises an elongated, preferably cylindrical, portion extending between a base portion and said closed distal end portion,

An inlet opening into the base for receiving liquid fuel from the fuel valve,

A plurality of straight nozzle bores, each leading to the outer surface of the nozzle body at a different radial angle,

A single straight main bore extending longitudinally from the inlet into the nozzle body,

At least two of the straight nozzle holes are connected to the straight main hole by means of separate feed channels, which are arranged at an angle to the straight main hole and the associated straight nozzle hole,

The valve needle comprises a distal end portion having a cylindrical end portion carried by the stem and journalled in a close fitting manner in the straight main bore such that the separate supply passage is fluidly disconnected from the main straight bore when the valve needle is in the closed position.

By providing separate feed channels at an angle to the straight nozzle bore and the main nozzle bore, a greater degree of freedom is provided for selecting the angle of the straight nozzle bore relative to the main axis and its position in the nozzle body material, allowing for the selection of the position and orientation of the nozzle bores, which results in more nozzle body material between adjacent nozzle bores, thereby reducing the thermal coefficient and thermal stress associated with crack formation without the need to increase the overall size of the nozzle, in particular the diameter of the cylindrical portion of the nozzle.

According to a possible implementation form of the first aspect, the individual feed channels are directed away from the longitudinal axis at a first angle to the longitudinal axis, as seen from the position where the associated individual feed channels are connected to the main bore, resulting in the "bases" of the straight nozzle bores being arranged more radially outwards, allowing a larger distance between adjacent straight nozzle bores and thus more nozzle body material between adjacent nozzle bores. In this context, a "base" position is a position where the straight nozzle holes are connected to the associated individual feed channels.

According to a possible implementation form of the first aspect, the straight nozzle bores are directed away from the longitudinal axis at a second angle to the longitudinal axis, the second angle being larger than the first angle, as seen from the position where the associated straight nozzle bores are connected to the separate feed channels.

According to a possible implementation form of the first aspect, the separate feed channel is a straight bore, preferably with rounded, i.e. spherical, ends to reduce stress in the nozzle bore material

According to a possible implementation of the first aspect, the cylindrical end portion fluidly connects the separate supply channel to the main straight bore when the valve needle is in the open position.

According to a possible implementation of the first aspect, the cylindrical end portion covers the opening of the separate supply channel towards the straight main bore when the valve needle is in the closed position.

The cylindrical end portion does not cover said opening of the separate supply channel towards said straight main bore when the valve needle is in the open position.

According to a possible embodiment of the first aspect, the separate supply channel opens into the main bore at a given axial distance from the inlet and the cylindrical end portion extends beyond the given axial distance in the closed position of the valve needle.

According to a possible embodiment of the first aspect, the axially displaceable valve needle is slidably received in a longitudinal bore in an elongated valve housing, the valve needle resting on a valve seat in a closed position, preferably a conical valve seat, the valve needle lifting from the valve seat in an open position, and the valve needle preferably being biased towards the closed position, and preferably the fuel chamber being arranged around the valve needle and opening into the valve seat.

According to a possible implementation of the first aspect, the fuel valve comprises a fuel inlet port in an elongated fuel valve housing for connection to a source of liquid fuel.

According to a possible implementation of the first aspect, the straight nozzle holes of the straight nozzle holes have substantially equal cross-sectional areas or diameters, and preferably all of the straight nozzle holes also have substantially equal lengths.

According to a possible implementation of the first aspect, the straight nozzle holes in the straight nozzle holes have equal diameters, and preferably the individual supply channels have a diameter that is larger than the diameter of the straight nozzle holes.

According to a possible implementation of the first aspect, the straight main bore is formed in a bushing, which is firmly received in a bore in the valve body.

According to a possible embodiment of the first aspect, the cylindrical end portion is hollow to form a fluid channel, the fluid channel preferably opening out of the handle at the proximal end and the fluid channel preferably opening out in the axial direction at the distal end.

According to one possible implementation of the first aspect, the straight nozzle holes open onto the cylindrical surface.

According to a possible implementation of the first aspect, a rounded transition surface is preferably arranged between the substantially cylindrical surface and the flat distal surface of the nozzle body.

According to a possible implementation of the first aspect, the straight nozzle holes open into the cylindrical surface and/or the transition surface.

According to one possible embodiment of the first aspect, the straight nozzle holes each have a nozzle axis I, II, III, IV, V, and wherein the nozzle axis I, II, III, IV of each of the nozzle holes is arranged at an obtuse angle α to the main direction X.

According to a possible embodiment of the first aspect, the radial component of each of the nozzle axes I, II, III, IV, V with respect to the main axis X is distributed over, preferably substantially equally over, a circular sector having an arc of less than 120 degrees, preferably an arc of less than 110 degrees, even more preferably less than 100 degrees.

According to a possible implementation of the first aspect, at least three of the straight nozzle holes are connected to the straight main hole by separate supply channels arranged at an angle to the straight main hole and the associated straight nozzle holes.

According to a second aspect there is provided a large two-stroke turbocharged uniflow scavenged internal combustion engine with a crosshead, comprising a fuel valve according to the first aspect or any implementation form thereof.

These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.

Drawings

In the following detailed portion of the disclosure, the invention will be described in more detail with reference to exemplary embodiments shown in the drawings, in which:

Figure 1 is a front view of the front end and one lateral side of a large two-stroke unit flow scavenged turbocharged engine according to an exemplary embodiment,

Figure 2 is a front view of the rear end and the other lateral side of the engine of figure 1,

Figure 3 is a schematic view of the engine according to figure 1 and its intake and exhaust systems,

Figure 4 is a cross-sectional view of an embodiment of a fuel valve for use in the engine used in figures 1 to 3,

Figure 5 is a cross-sectional view of another embodiment of a fuel valve for use in the engine of figures 1-3,

Figure 6 is a front perspective view of the nozzle of the fuel valve of figure 4 or figure 5,

Figure 7 is a cross-sectional view of the nozzle of figure 6,

Fig. 8 is a cross-sectional view of the tip of the nozzle of fig. 6, wherein the distal cylindrical portion of the valve needle is in an open position,

Fig. 9 is the view of fig. 8, wherein the distal cylindrical portion of the valve needle is in the closed position,

Figure 10 is a perspective view of the tip of the spray nozzle of figure 6,

FIG. 11 is another cross-sectional view of the tip end of the spray nozzle of FIG. 6 with the distal cylindrical portion of the valve needle in the closed position, and

FIG. 12 is a graphical representation of the position of the nozzle of the fuel valve of FIG. 5 in the cylinder head as viewed from the side of the piston and showing the orientation of the nozzle bores and the resulting fuel jets.

Detailed Description

In the following detailed description, a fuel valve and a large two-stroke engine using the same will be described by way of example embodiments. Fig. 1-3 show a large low-speed turbocharged two-stroke internal combustion engine with a crankshaft 22 and a crosshead 23. FIG. 3 shows a schematic diagram of a large low speed turbocharged two-stroke internal combustion engine with an intake system and an exhaust system. In this exemplary embodiment, the engine has six cylinders (formed by the cylinder liner 1) in line. Large turbocharged two-stroke internal combustion engines typically have between five and sixteen in-line cylinders carried by an engine frame 24. The engine may for example be used as a main engine in an ocean going vessel or as a stationary engine for operating a generator in a power station. The total output of the engine may be, for example, in the range of 5,000kw to 110,000 kw.

The engine may be a two-stroke uniflow diesel (compression ignition) engine with a scavenging port 19 in the form of a ring of piston control ports at the lower region of the cylinder liner 1 and an exhaust valve 4 at the top of the cylinder liner 1. The flow in the combustion chamber is thus always from bottom to top, so the engine is of the so-called unidirectional flow type. The scavenging air flows from the scavenging air receiver 2 to the scavenging air ports 19 of the respective cylinders formed by the cylinder liner 1. The reciprocating piston 21 in the cylinder liner 1 compresses the scavenging gas, and the fuel is ejected through nozzles of two or three fuel valves 30 provided in the cylinder head 26. And subsequently burns and produces exhaust gas. When the exhaust valve 4 is opened, the exhaust gases flow through an exhaust line 20 associated with the cylinder 1 into the exhaust gas receiver 3 and onward through the first exhaust conduit 18 to the turbine 6 of the turbocharger 5, from where the exhaust gases are discharged through the second exhaust conduit 7. The turbine 6 drives a compressor 9 via a shaft 8, which is fed via an air inlet 10.

The compressor 9 delivers pressurized charge air to a charge air conduit 11 leading to the charge air receiver 2. The scavenging air in the conduit 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, which auxiliary blower 16 pressurizes the charge air flow to the charge air receiver 2 at low or partial load. At higher loads, the turbocharger compressor 9 delivers sufficient compressed scavenging air, while the auxiliary blowers 16 are bypassed via check valves 15.

A cylinder is formed in the cylinder liner 1. The cylinder liner 1 is carried by a cylinder frame 25, and the cylinder frame 25 is supported by an engine frame 24.

Fig. 4 shows an embodiment of one of two or three fuel valves 30 installed in the through-hole in the cylinder head 26 of each cylinder, in which the rear end 31 of the fuel valve 30 protrudes from the upper side of the cylinder head 26 and the distal end (tip end) of the nozzle 40 protrudes slightly into the combustion chamber. The fuel valve 30 includes an elongated fuel valve body 32, and the fuel valve body 32 has a nozzle holder at a distal end portion (front end portion) 33 thereof. The nozzle retainer connects the nozzle 40 to the elongated fuel valve body 32. Liquid fuel (e.g., ethanol, methanol, diesel, heavy fuel oil) is delivered to the combustion chamber 14 via a nozzle 40 through a fuel valve 30 in a controlled and timed manner. The fuel valve 30 shown in fig. 4 has an elongate outer housing 32, the outer housing 32 having a head at its proximal end 31, by means of which the fuel valve 30 can be mounted in the cylinder head 26 in a known manner and connected to a fuel pump (not shown) of the internal combustion engine.

The head at the proximal portion 31 includes a fuel inlet 83, the fuel inlet 83 being in flow communication with a conduit extending through the valve body 32. An axially displaceable valve needle 35 is journalled in the valve housing 32 and has an open position in which the valve needle 35 is lifted from a preferably conical valve seat 36 and a closed position in which a mating portion of the valve needle 35 rests in a sealing manner on the valve seat 36. The valve needle is resiliently biased towards the closed position by resilient means, which in this embodiment is formed by a coil spring 83. The lifting of the valve needle 35 against the bias of the coil spring 83 is caused by the pressure of the fuel supplied to the fuel valve 30 acting on the surface of the valve needle 35 or by the pressure of a piston or plunger operatively connected to the valve needle 35. A fuel chamber 68 surrounds the valve needle 35 and opens into the valve seat 36.

The fuel valve 30 carries a nozzle 40 at its distal end 33. The nozzle 40 is configured such that when the fuel valve 30 is mounted on the cylinder head 26, the nozzle 40 protrudes into the combustion chamber 14 of the engine cylinder liner 1.

In this embodiment, the fuel valve comprises an axially movable valve needle 35, the valve needle 35 comprising a tapered portion that mates with a tapered seat 36 in the longitudinal housing 32 of the fuel valve 30.

Fig. 12 shows how the nozzle 40 is positioned at the outer periphery of the cylinder head 26 and shows the direction of fuel injection (this direction corresponds to the direction of the axes I, II, III, IV and V of the straight nozzle holes 45 in the nozzle 40). The direction of the swirl of the gas in the combustion chamber is shown by curved dashed arrow 66.

Fig. 5 shows a fuel valve 30 according to another embodiment, the fuel valve 30 being similar to the embodiment of fig. 4, except that the fuel valve 30 includes a booster pump to amplify the pressure of the fuel supplied to the fuel valve 30. The main component of the booster pump is a booster plunger 80. The other components of the fuel valve 30 and the nozzle 40 according to the present embodiment are conceptually identical to those of the fuel valve of fig. 4.

Fig. 6-11 show the nozzle 40 and the distal end portion of the valve needle 35 in more detail.

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

Inlet 48 opens into base 42 for receiving liquid fuel from fuel valve 30 when valve needle 35 is in the open position. A single straight main bore 50 extends longitudinally into the nozzle body from the inlet 48. In the present embodiment, the straight main bore 50 is formed in a bushing 51, which bushing 51 is securely received in the bore 51 in the valve body, such as by a shrink fit, but it should be understood that the nozzle may be constructed without a bushing 51 such that the nozzle body is made of a single piece of material.

The closed distal end (tip end) 44 includes a generally flat end surface 47 having a circular or oval profile. The end surface 47 is connected to the cylindrical portion via a curved or rounded transition surface 46.

The nozzle 40 is provided with a plurality of straight nozzle holes 45. The nozzle 40 is provided with any desired number of nozzle holes 45, preferably between three and seven nozzle holes 45, even more preferably between three and six nozzle holes 45, and most preferably the nozzle holes 45 are five or six nozzle holes 45. The nozzle 40 according to the present embodiment is provided with five nozzle holes 45.

Each straight nozzle bore 45 opens onto the outer surface of the nozzle body 43 at a different radial angle to inject a fan-shaped fuel ray (as shown in fig. 12) into the combustion chamber when the fuel valve 30 is open. Each straight nozzle bore 45 opens onto the outer surface of the nozzle body at a different radial angle. Preferably, the nozzle holes 45 open into the cylindrical surface 43 and/or into the transition surface 46.

The nozzle holes 45 each have a nozzle axis I, II, III, IV and V (fig. 10). The nozzle axes I, II, III, IV and V of each of the holes 45 are arranged at an obtuse angle α to the main axis X. The obtuse angle α may be different for each of the nozzle holes 45. The radial component of each of the nozzle axes I, II, III, IV, V relative to the main axis X is distributed over a circular sector having an arc of less than 120 degrees, preferably less than 110 degrees, even more preferably less than 100 degrees. The radial component of each of the nozzle axes (I, II, III, IV and V) relative to the main axis X is substantially evenly distributed over the circular sector to maximize the amount of nozzle body material between the individual nozzle holes 45.

The base 42 is provided with an inlet port 48 for receiving fuel from the fuel valve 30. The main bore 50 extends from said inlet port 48 into the nozzle body in the direction of the main axis X and into the cylindrical portion 43 to a position close to the distal end 44 of the nozzle body. The main bore 50 is connected to a plurality of individual feed channels 49, each feed channel 49 being connected to a nozzle bore 45. The individual feed channels 49 are arranged at an angle to the axis of the straight main bore 50 and at an angle to the axis of the straight nozzle bore 45, the associated individual feed channels 49 being connected to the straight nozzle bore 45.

The cross-sectional area of the main bore 50 is substantially larger than the total cross-sectional area of the feed passage 49. The total cross-sectional area of the supply passage 49 is approximately equal to the total cross-sectional area of the nozzle hole 45.

The use of separate feed channels 49 to connect the nozzle holes 45 to the main holes 50 allows the nozzle holes 45 to be arranged such that the amount of nozzle body material between the nozzle holes 45 is maximized while still having the axis I, II, III, IV of the nozzle holes 45 and V covered with the fuel jet to the desired circular sector.

In an embodiment, the inlet port 48 is formed by a bore having a diameter greater than the diameter of the main bore 50. Alternatively, the inlet port 48 may have the same diameter as the main bore.

The nozzle 40 provides a wide distribution of nozzle holes 45 and thus more nozzle material between the nozzle holes 45 and thus better resistance to crack formation. In addition, the nozzle 40 provides uniform inlet conditions for each nozzle hole 45 for producing a substantially uniform fuel jet.

The valve needle 35 comprises a distal end portion comprising a cylindrical end portion 39 carried by a stem 38. The cylindrical end portions 39 are journalled in the straight main bore 50 in a tight fit to fluidly disconnect the individual supply channels 49 from the main straight bore 50 when the valve needle 35 is in the closed position as shown in fig. 7, 9 and 11, because the cylindrical end portions 39 cover the openings of the respective supply channels 49 towards said straight main bore 50 when the valve needle 35 is in the closed position. Thus, any 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.

The cylindrical end portion 39 is hollow to form a fluid passage 71 for fuel from the proximal side of the cylindrical end portion 39 to the distal side of the cylindrical end portion 39. The fluid channel 71 opens out of the handle 38 at a proximal end and the fluid channel 71 is open distally in an axial direction.

When the valve needle 35 is in the open position, as shown in fig. 8, the cylindrical end portion 39 fluidly connects the separate supply passage 49 to the main straight bore 50, since the cylindrical end portion 39 does not cover the opening of the separate supply passage towards said straight main bore 50.

The individual feed channels 49 open into the main bore at a given axial distance from the inlet 48 and the cylindrical end portion 39 extends beyond the given axial distance in the closed position of the valve needle 35 to block fuel flow to the individual feed channels 49.

In an embodiment, the individual feed channels 49 are directed at a first angle from the longitudinal axis X away from the longitudinal axis X, as seen from the location where the associated individual feed channel 49 connects to the main bore 50, thereby forming a more radially outwardly placed "base" of the straight nozzle bores 45, thereby allowing for a greater distance between adjacent straight nozzle bores 45 and thus allowing for more nozzle body material between adjacent straight nozzle bores 45. Herein, the "base" position is where the straight nozzle holes 45 are connected to the individual supply channels 49.

In an embodiment, the straight nozzle bores 45 are directed away from the longitudinal axis X at a second angle from the position of the associated nozzle bores 45 connected to the separate feed channel 49, which second angle is larger than the first angle.

According to a possible implementation form of the first aspect, the separate feed channel 49 is a straight bore, preferably with a rounded, i.e. spherical end ("base" or "near base") to reduce stresses in the nozzle bore material.

The invention has been described herein in connection with various embodiments. However, other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. The reference signs used in the claims shall not be construed as limiting the scope.

Claims

1. A fuel valve (30) for injecting liquid fuel into a large two-stroke turbocharged uniflow scavenged internal combustion engine having a crosshead, the fuel valve (30) comprising:

An elongated fuel valve housing (32), the elongated fuel valve housing (32) having a longitudinal axis (X), a proximal end and a distal end (33),

An axially displaceable valve needle (35), the valve needle (35) having a closed position in which the valve needle (35) rests on a valve seat (36), and an open position in which the valve needle (35) is lifted from the valve seat (36), and

An atomizer nozzle (40), said atomizer nozzle (40) being arranged at said distal end (33) of said elongated fuel valve housing (32),

The atomizer nozzle (40) having a nozzle body extending along the longitudinal axis (X) from a base (42) at a proximal end of the nozzle body to a closed distal end (44) of the nozzle body, the base (42) being attached to the fuel valve (30),

The nozzle body includes:

an elongated portion (43), said elongated portion (43) extending between said base portion (42) and said closed distal end portion (44),

An inlet (48), said inlet (48) leading to said base (42) for receiving liquid fuel from said elongated fuel valve housing (32),

A plurality of straight nozzle holes (45), each straight nozzle hole (45) opening onto the outer surface of the nozzle body at a different radial angle,

A single straight main bore (50), said straight main bore (50) extending longitudinally from said inlet (48) into said nozzle body,

It is characterized in that the method comprises the steps of,

At least three of the straight nozzle holes (45) are connected to the straight main hole (50) by means of separate feed channels (49), which separate feed channels (49) are arranged at an angle to the straight main hole (50) and the associated straight nozzle hole (45),

The valve needle (35) comprises a distal end portion having a cylindrical end portion (39) carried by a shank (38), and the cylindrical end portion (39) is journalled in the straight main bore (50) in a close fit such that the separate supply channel (49) is fluidly disconnected from the straight main bore (50) when the valve needle (35) is in the closed position.

2. The fuel valve (30) of claim 1 wherein the cylindrical end portion (39) fluidly connects the separate supply passage (49) to the straight main bore (50) when the valve needle (35) is in the open position.

3. The fuel valve (30) according to claim 1 or 2, wherein the cylindrical end portion (39) covers the opening of the separate supply channel (49) towards the straight main bore (50) when the valve needle (35) is in the closed position.

4. The fuel valve (30) according to claim 2, wherein the cylindrical end portion (39) does not cover the opening of the separate supply channel (49) towards the straight main bore (50) when the valve needle (35) is in the open position.

5. The fuel valve (30) according to claim 1, wherein the separate feed channel (49) opens into the straight main bore at a given axial distance from the inlet (48), and wherein the cylindrical end portion (39) extends beyond the given axial distance in the closed position of the valve needle (35).

6. The fuel valve (30) of claim 1 wherein an axially displaceable valve needle (35) is slidably received in a longitudinal bore (64) in the elongated fuel valve housing (32), the axially displaceable valve needle (35) resting on a valve seat (36) in the closed position, and the axially displaceable valve needle (35) lifting from the valve seat (36) in the open position, and the axially displaceable valve needle (35) being biased toward the closed position, and a fuel chamber (68) surrounding the axially displaceable valve needle (35) and opening to the valve seat (36).

7. The fuel valve (30) of claim 1, comprising a fuel inlet port (34) in the elongated fuel valve housing (32) for connection to a liquid fuel source.

8. The fuel valve (30) of claim 1, wherein all of the straight nozzle holes (45) have at least one of an equal cross-sectional area, an equal diameter, and an equal length.

9. The fuel valve (30) of claim 1, wherein the straight main bore (50) is formed in a bushing (51), the bushing (51) being securely received in a bore in the nozzle body.

10. The fuel valve (30) of claim 1, wherein the cylindrical end portion (39) is hollow to form a fluid channel (71), the fluid channel (71) opening out of the stem (38) at a proximal end, and the fluid channel (71) opening distally in an axial direction.

11. The fuel valve (30) of claim 1, wherein the straight nozzle bore (45) opens onto an outer surface of the elongated portion (43).

12. The fuel valve (30) of claim 1, comprising a rounded transition surface (46) between an outer surface of the elongated portion (43) and a planar distal end surface (47) of the nozzle body.

13. The fuel valve (30) according to claim 12, wherein the straight nozzle bore (45) opens into an outer surface of the elongated portion (43) and/or into the transition surface (46).

14. The fuel valve (30) of claim 1, wherein the straight nozzle bores (45) each have a nozzle axis (I, II, III, IV, V), and wherein the nozzle axis (I, II, III, IV, V) of each of the straight nozzle bores (45) is arranged at an obtuse angle a to the longitudinal axis (X).

15. The fuel valve (30) of claim 14, wherein a radial component of each of the nozzle axes (I, II, III, IV, V) relative to the longitudinal axis (X) is distributed over a circular sector having an arc of less than 120 degrees.

16. The fuel valve (30) of claim 14, wherein a radial component of each of the nozzle axes (I, II, III, IV, V) relative to the longitudinal axis (X) is distributed over a circular sector having an arc of less than 110 degrees.

17. The fuel valve (30) of claim 14, wherein a radial component of each of the nozzle axes (I, II, III, IV, V) relative to the longitudinal axis (X) is distributed over a circular sector having an arc of less than 100 degrees.

18. The fuel valve (30) of claim 14 or 15, wherein a radial component of each of the nozzle axes (I, II, III, IV, V) relative to the longitudinal axis (X) is equally distributed over a circular sector having an arc of less than 120 degrees.

19. The fuel valve (30) of any of claims 14-16, wherein a radial component of each of the nozzle axes (I, II, III, IV, V) relative to the longitudinal axis (X) is equally distributed over a circular sector having an arc of less than 110 degrees.

20. The fuel valve (30) of any of claims 14-17, wherein a radial component of each of the nozzle axes (I, II, III, IV, V) relative to the longitudinal axis (X) is equally distributed over a circular sector having an arc of less than 100 degrees.

21. A large two-stroke turbocharged uniflow scavenged internal combustion engine with a crosshead, comprising a fuel valve (30) according to any one of claims 1 to 20.