JP7717311B2 - Fuel valve for injecting fuel into the cylinder of a large turbocharged two-stroke uniflow scavenged internal combustion engine, and engine equipped with such a fuel valve - Google Patents

Description

The matter disclosed in this application (hereinafter referred to as the present disclosure) relates to a fuel valve that injects liquid fuel into the cylinders of a large turbocharged, two-stroke, uniflow-scavenged internal combustion engine.

background

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

The cylinder of this type of engine has a single exhaust valve located in the center of the cylinder cover, i.e., the top of the cylinder, and a ring of piston-controlled scavenging ports located at the bottom of the cylinder liner. Gas is always transported from bottom to top within the cylinder, hence the name uniflow scavenging. The scavenging ports are arranged at an angle, which creates a vortex in the gases within the combustion chamber.

The cylinder cover has two or three fuel valves arranged around a centrally located exhaust valve. The fuel valve nozzles protrude 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 oriented in the direction of the swirl into the combustion chamber, pointing away from the cylinder wall. Sometimes, one nozzle hole is oriented against the swirl in the combustion chamber.

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.

Known nozzles for large, crosshead, two-stroke diesel engines typically have an elongated body. The nozzle body has a cylindrical section with a straight main bore. This main bore leads from the nozzle base 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 face downward relative 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 top surface of the piston is very close to the tip of the nozzle). For this reason, the nozzle holes are oriented primarily transverse to the nozzle/fuel valve axis, typically approximately perpendicular to the engine cylinder axis. Typically, each nozzle has three to seven nozzle holes, all connected to the main bore.

Typically, known fuel valves for injecting liquid fuels include a conical valve seat and a cooperating axially displaceable valve needle to control fuel flow to the nozzle. The forward portion of the valve needle consists of a distal cylindrical portion that is snugly 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, thereby significantly reducing the so-called suction volume, i.e., the residual volume (RV) of fuel within the space defined by the main bore within the nozzle. Without this slide valve structure, the residual fuel in the main bore (and nozzle bore) would drip into the combustion chamber after fuel injection ends, adversely affecting fuel consumption, reliability, and emissions.

Because the nozzle body protrudes into the combustion chamber, it is exposed to the hot gases in the combustion chamber, with parts of the nozzle body reaching relatively high temperatures of up to approximately 400°C. In engines running on heavy fuel oil, the temperature of the incoming fuel is approximately 140°C. This means that the incoming fuel in the main bore, which exits the nozzle through the nozzle holes, has a significantly lower temperature than the gas surrounding the outer surface of the nozzle body. This exposes the nozzle body material to significant temperature gradients, which causes stress in the nozzle material.

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

This problem cannot be solved simply by increasing the spacing between nozzle holes, increasing the amount of material between them, and reducing the temperature gradient. This is because increasing the nozzle diameter is highly undesirable, as it would likely increase the amount of heat transferred from the combustion chamber to the nozzle. Furthermore, because two or three fuel valves are located around the periphery of the cylinder cover, limiting the radial extent of the nozzle holes to an angle of approximately 110°, it is not possible to simply increase the radial spacing between the nozzle holes. This is particularly true when there is a slide valve within the nozzle, which requires the main hole within the nozzle to have a certain diameter, thereby limiting the wall thickness of the nozzle body. Furthermore, fuel valves with a slider within the nozzle body require that the nozzle holes, when injecting fuel simultaneously, open at substantially the same axial distance from the base of the nozzle to the main hole.

US Patent No. 5,765,755A discloses an injection rate shaping nozzle assembly for a fuel injection system. The nozzle assembly includes a closed nozzle valve element and an injection rate shaping control device having an injection spill circuit that vents a portion of the injected fuel to generate a predetermined change in the flow rate of fuel injected into the combustion chamber over time. The spill circuit includes a spill passage integrally formed in the nozzle valve element. The injection rate shaping control device can include a spill acceleration chamber formed in the nozzle valve element to generate a sudden increase in the spill flow rate. A spill circuit purge device is also provided to remove fuel from the outlet circuit and acceleration chamber between injection events, thereby ensuring an unimpeded and effective flow of spilled fuel during the next spill event. The purge device includes a purge passage sized 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.

Abstract

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, crosshead, two-stroke, uniflow-scavenged internal combustion engine that overcomes or at least reduces the above-mentioned problems.

These and other problems are solved by the features of the independent claims. More specific implementations will become apparent from the dependent claims, the description and the drawings.

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 comprises:
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 opening into the base for receiving liquid fuel from the fuel valve housing;
a plurality of straight nozzle holes each opening into the 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 paths, and the individual supply paths are disposed obliquely with respect to the nozzle holes and the main hole to which the individual supply paths are connected;
The valve needle has a distal portion with 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.

By providing separate feed passages that are angled relative to the straight nozzle bore and the main nozzle bore, greater flexibility is provided for selecting the angle of the straight nozzle bore relative to the main axis and the location of these nozzle bores in the nozzle body material. This makes it possible to select a nozzle bore location and orientation that allows for more nozzle body material between adjacent nozzle bores, reducing the thermal coefficient and the formation of cracks associated with thermal stress, without increasing the overall size of the nozzle, particularly the diameter of the cylindrical portion of the nozzle.

In one implementation of the first approach, the individual supply passages are oriented away from the longitudinal axis at a first angle relative to the longitudinal axis, as viewed from where they connect to the main bore, such that the "bases" of the nozzle holes are positioned further radially outward, thereby increasing the distance between adjacent nozzle holes and therefore the amount of 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.

In one implementation of the first concept, the straight nozzle holes are oriented away from the longitudinal axis X at a second angle relative to the longitudinal axis X, as viewed from the point where the nozzle holes connect to the individual supply channels, where the second angle is greater than the first angle.

In one example implementation of the first approach, the individual supply channels are straight holes, preferably with rounded or blunt ends to reduce stress on the nozzle hole material.

In one example implementation of the first concept, the cylindrical end fluidly connects the individual supply passages to the straight main bore when the valve needle is in an open position.

In one example implementation of the first concept, the cylindrical end covers the opening of the individual supply passage to the straight main bore when the valve needle is in the closed position.

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

In one example implementation of the first concept, 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 the closed position.

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 the closed position, the valve needle seats on a valve seat, which is preferably a conical valve seat. In the open position, the valve needle lifts from the valve seat. The valve needle is preferably biased toward the closed position. A fuel chamber is preferably provided surrounding the valve needle and opening to the valve seat.

In one example 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.

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

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

In one implementation of the first concept, the straight main hole is formed in a bushing. The bushing is tightly fitted into the bore of the valve body.

In one example of the first implementation, the cylindrical end is hollow to form a fluid passage. The fluid passage preferably opens proximally to the exterior of the handle and axially distally.

In one example of the first implementation, the multiple straight nozzle holes each open into a cylindrical surface.

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

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

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

In one example implementation of the first approach, the radial components of each of the nozzle axes I, II, III, IV, and 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 are preferably distributed substantially evenly.

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

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

These and other aspects of the present invention will be further elucidated by the examples described below.

The invention will now be explained in more detail with reference to exemplary embodiments shown in the drawings.
1 is a perspective view of a front and one side of a large two-stroke unit flow scavenged turbomachine according to an exemplary embodiment; FIG. 2 is a perspective view showing the after end and other side of the engine of FIG. 1; FIG. 2 is a diagram of the intake system and exhaust system of the engine of FIG. 1. FIG. 4 is a cross-sectional view of one embodiment of a fuel valve for use with the engine of FIGS. 1-3. FIG. 4 is a cross-sectional view of another embodiment of a fuel valve for use in the engine of FIGS. 1 to 3. FIG. 6 is a perspective view of a nozzle of the fuel valve of FIG. 4 or FIG. 5 . FIG. 7 is a cross-sectional view of the nozzle of FIG. 6. 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. 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 the closed position. 7 is a transparency of the nozzle tip of FIG. 6. 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. 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

The following detailed description describes, in exemplary embodiments, a fuel valve and a large two-stroke engine in which the fuel valve is used. 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, along with its intake and exhaust systems. In this exemplary embodiment, the engine has six cylinders arranged in series. Each cylinder is formed by a cylinder liner 1. Large turbocharged, two-stroke internal combustion engines typically have five to sixteen cylinders arranged in series. The cylinders are supported by an engine frame 24. Such engines can be used, for example, as main engines on ocean-going ships or as stationary engines for driving generators in power plants. The total engine power output can be, for example, in the range of 5,000 to 110,000 kW.

The engine can be a two-stroke uniflow diesel engine (compression ignition engine). The lower region of the cylinder liner 1 is provided with a ring-shaped scavenging port 19, which is a port controlled by the piston, and an exhaust valve is located at the center of the top of the cylinder liner 1. Therefore, the flow within the combustion chamber is always from bottom to top, making the engine a so-called uniflow type. Scavenging air is guided through a scavenging receiver 2 to the scavenging ports 19 of each cylinder, each formed by a cylinder liner 1. A reciprocating piston 21 within the cylinder liner 1 compresses the scavenging air, and fuel is injected through nozzles of two or three fuel valves 30 located on the cylinder cover 26. Combustion occurs, generating exhaust gases. 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 the turbine 6 of the turbocharger 5. From there, the exhaust gases are discharged through a second exhaust pipe 7. The turbine 6 drives a compressor 9 via a shaft 8. Air is supplied to the compressor 9 through an air inlet 10.

The compressor 9 delivers compressed scavenging air into 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 to cool the charge air. The cooled charge air then passes through an auxiliary blower 16, driven by an electric motor 17. The auxiliary blower 16 compresses the charge air flow to 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 sufficient compressed scavenging air, and the auxiliary blower 16 is bypassed by a check valve 15.

The cylinder is formed in a cylinder liner 1. The cylinder liner 1 is supported by a cylinder frame 25. The cylinder frame 25 is supported by a period frame 24.

FIG. 4 shows one embodiment of two or three fuel valves 30 mounted within a throughbore in the cylinder cover 26 of each cylinder. The fuel valve 30 is mounted in the throughbore of the cylinder cover 26 with its rear end 31 protruding from the top 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 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 valve 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 attached 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.

The head of the proximal end 31 has a fuel inlet 83. The fuel inlet 83 is in fluid communication with a duct extending through the valve body 32. An axially displaceable valve needle 35 is slidably disposed within the valve housing 32 and has an open position in which the valve needle 35 is clear of a (preferably conical) valve seat 36, and a closed position in which the valve needle 35 (the portion 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 resiliently biased toward the closed position by elastic means formed, in this embodiment, by a helical spring 83. 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. Specifically, this pressure is caused by acting on the surface of the valve needle 35 or 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 carries a nozzle 40 at its distal end 33. The nozzle 40 is configured to protrude into the combustion chamber 14 of the engine cylinder liner 1 when the fuel valve 30 is attached to the cylinder cover 26.

In this embodiment, the fuel valve includes an axially movable valve needle 35. The valve needle 35 has a conical portion that cooperates with a conical seat 36 within the elongated housing 32 of the fuel valve 30.

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

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

Figures 6 to 11 show the nozzle 40 and the distal portion of the valve needle 35 in more detail.

The nozzle 40 has a nozzle body extending from a base 42 at the proximal end to a closed distal end 44 that forms the tip of the 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 known in the art.

An inlet 48 opens into the base 42 for receiving liquid fuel from the fuel valve 30 when the valve needle 35 is in the open position. A single straight main bore 50 extends longitudinally from the inlet 48 into the nozzle body. In this embodiment, the straight main bore 50 is formed in a bushing 51, which is tightly fitted, for example by shrink fitting, within the 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.

The closed distal end (tip) 44 has a substantially planar end surface 47 with a circular or elliptical profile. The end surface 47 is connected to the cylindrical portion via a curved or rounded transition surface 46.

The nozzle 40 has 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 in this embodiment has five nozzle holes 45.

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, it creates a fan-shaped fuel jet 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.

Each nozzle hole 45 has a nozzle axis I, II, III, IV, and V (FIG. 10). The nozzle axis I, II, III, IV, and V of each nozzle hole 45 is disposed at an obtuse angle α with respect to the primary axis X. This obtuse angle α may vary from nozzle hole 45 to nozzle hole 45. The radial component of each nozzle axis I, II, III, IV, and V with respect to the primary axis X is distributed over a sector having an arc of less than 120 degrees, preferably less than 110 degrees, and more preferably less than 100 degrees. The radial component of each nozzle axis (I, II, III, IV, and V) with respect to the primary axis X is distributed substantially evenly over the circular cross section to maximize the amount of nozzle body material between individual nozzle holes 45.

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, along the main axis X, into the cylindrical portion 43, and reaches a position near the distal end 44 of the nozzle body. The main bore 50 connects to a plurality of individual supply passages 49, each of which leads to a nozzle bore 45. Each individual supply passage 49 is arranged at an angle relative to the axis of the straight main bore 50 and the axis of the straight nozzle bore 45 to which it is connected.

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.

By using separate supply passages 49 to connect each nozzle hole 45 to the main bore 50, multiple nozzle holes 45 can be positioned to maximize the amount of nozzle body material between them. Additionally, the axes I, II, III, IV, and V of the nozzle holes 45 can be positioned so that the fuel jet covers a desired circular sector.

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

The nozzle holes 45 in the nozzle 40 are widely dispersed, 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 create a substantially uniform fuel jet.

The valve needle 35 has a distal portion with a cylindrical end 39 carried by the stem 38. The cylindrical end 39 fits snugly and slidably into 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 separates the individual supply passage 49 from the main bore 50. Therefore, 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 39 is hollow to form a fluid passage 71 for fuel from the proximal side of the cylindrical end 39 to the distal side of the cylindrical end 39. The fluid passage 71 opens proximally to the exterior of the stem 38 and opens distally in the axial direction.

As shown in FIG. 8, the cylindrical end 39 does not cover the openings from the individual supply channels 49 to the main bore 50 when the valve needle 35 is in the open position. Therefore, the cylindrical end 39 fluidly connects each individual supply channel 49 to the main bore 50 when the valve needle 35 is in the open position.

Each individual supply passage 49 opens into the main bore at a predetermined axial distance from the inlet 48. When the valve needle 35 is in the closed position, the cylindrical end 39 extends beyond the predetermined axial distance, preventing fuel from flowing to each individual supply passage 49.

In some embodiments, the individual supply passages 49 are oriented at a first angle relative to the longitudinal axis X in a direction away from the longitudinal axis X, relative to the location where the individual supply passages 49 connect to the main bore 50, such that the "bases" of the nozzle holes 45 are positioned 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 supply passages 49.

In some embodiments, the straight nozzle holes 45 are oriented in a direction away from the longitudinal axis X at a second angle relative to the longitudinal axis X, when viewed from the position where the nozzle holes 45 connect to the individual supply channels 49. Here, the second angle is greater than the first angle.

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

The present invention has been described using various examples. However, upon reviewing 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 implementing the claimed invention. The words "comprise," "have," and "include" in the claims do not exclude the presence of additional elements or steps. A claim without an explicit recitation of a plurality of elements does not exclude the presence of a plurality of those elements. The fact that several items are recited in separate dependent claims does not exclude them from being combined, and may be combined to advantage. Reference signs used in the claims should not be construed as limiting the scope of the invention.

Claims (16)

A fuel valve for injecting liquid fuel into a crosshead type large two-stroke turbocharged uniflow scavenged 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
an elongated portion between the base and the closed distal end;
an inlet opening into the base for receiving liquid fuel from the fuel valve housing;
a plurality of straight nozzle holes each opening into the 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 with a cylindrical end supported on a stem, the cylindrical end slidably fitting within the straight main bore to fluidly isolate the separate supply passages from the straight main bore when the valve needle is in the closed position;
Fuel valve. The fuel valve of claim 1, wherein the cylindrical end fluidly connects the individual supply passages to the straight main bore when the valve needle is in an open position. The fuel valve of claim 1, wherein the cylindrical end covers the openings of the individual supply passages that lead to the straight main bore when the valve needle is in the closed position. The fuel valve of claim 2, wherein when the valve needle is in the open position, the cylindrical end does not cover the openings of the individual supply passages to the straight main bore. 2. The fuel valve of claim 1, wherein the individual supply passages open into the main straight bore a predetermined axial distance from the inlet, and the cylindrical end extends beyond the predetermined axial distance when the valve needle is in a closed position. The fuel valve of claim 1, wherein the valve needle is slidably received within the 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. The fuel valve of claim 1, wherein the elongated fuel valve housing includes a fuel inlet port for connection to a liquid fuel source. The fuel valve of claim 1, wherein the plurality of straight nozzle holes all have the same cross-sectional area or diameter. The fuel valve of claim 1, wherein the straight main hole is formed in a bushing, and the bushing is tightly fitted into the bore of the nozzle body. The fuel valve of claim 1, wherein the cylindrical end is hollow to form a fluid passage. A fuel valve as described in claim 1, wherein all of the multiple straight nozzle holes open into the surface of the cylindrical end. The fuel valve of claim 1, further comprising a rounded transition surface between the cylindrical end surface and the flat distal end surface of the nozzle body. A fuel valve as described in claim 12, wherein all of the plurality of straight nozzle holes open into the cylindrical end surface or the transition surface. The fuel valve of claim 1, wherein each of the plurality of straight nozzle holes has a nozzle axis disposed at an obtuse angle relative to the longitudinal axis. The fuel valve of claim 14, wherein the 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. A crosshead-type large two-stroke turbocharged uniflow scavenging internal combustion engine equipped with a fuel valve according to any one of claims 1 to 15.