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

Abstract

To provide a fuel valve that enables quick and accurate switching between a pilot injection and a main injection.SOLUTION: A fuel valve (30) for injecting liquid fuel into a combustion chamber of a crosshead type large two-stroke turbocharged uniflow scavenged internal combustion engine, and a crosshead type large two-stroke turbocharged uniflow scavenged internal combustion engine with such a fuel valve. The fuel valve (30) uses a resiliently-biased valve member (35) that is separated from a seat with the pressure of supplied fuel, and is configured to perform either a pilot fuel injection or a main fuel injection, using a hydraulic control system using fuel as the hydraulic medium. The fuel valve (30) is controlled by an electronic control valve for determining whether performing a pilot injection or performing a main injection when the externally supplied fuel pressure increases to a level for performing an injection event.SELECTED DRAWING: Figure 4

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, and to an engine equipped with such a fuel valve.

[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 usually have a nozzle body. This nozzle body has a cylindrical part 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). Typically, each nozzle has 3 to 7 nozzle holes, all of which are connected to the main holes. Fuel valves capable of both main and pilot injection usually also have one or two small pilot nozzle holes connected to the main holes. These valves usually have a displaceable valve member, where only the pilot nozzle hole is open when the valve member lift is small, and both the pilot nozzle hole and the main nozzle hole are open when the valve member lift is large.

[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 hole 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 hole) 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] KR102057802 discloses a fuel valve for a dual-fuel engine, comprising a valve body including a fuel passage through which fuel is supplied, a main injection hole communicating with the fuel passage, and a pilot injection hole, and a valve part having a single valve needle that is elastically supported and moves on the valve body to selectively open and close the main injection hole and the pilot injection hole depending on the fuel supply mode. The movement distance of the valve part is determined by a pressing force applied in the valve body. The valve needle simultaneously opens the main injection hole and the pilot injection hole when the fuel supply mode is a diesel mode, and opens only the pilot injection hole when the fuel supply mode is a gas mode. To limit the stroke to pilot injection only, a displaceable closure plunger provided in the fuel valve is acted upon by high-pressure hydraulic oil. This known fuel valve therefore requires a connection to a high-pressure hydraulic system in addition to a connection to the fuel supply system, and therefore such a hydraulic system must be provided in the engine, and each of the three or four fuel valves of the cylinder must be connected to the high-pressure hydraulic system via a double-walled pipe, and each fuel valve must be connected to a valve block having a hydraulic valve capable of handling high-pressure hydraulic oil. The valve must be designed to prevent hydraulic oil from mixing with the fuel and vice versa, so the fuel valve must be equipped with anti-contamination measures such as seals and pressure barriers. These requirements make the fuel valve expensive, the engine expensive because of the additional equipment required, and unreliable as there is always a risk of fuel and hydraulic oil mixing.

[0009] US4285471A discloses a fuel injection nozzle for an internal combustion engine, comprising: a nozzle body having a first set of fuel injection openings and fuel inlet means for applying pressurized fuel to the first set of injection openings; a valve needle slidable within the nozzle body; means for applying a closing force to the valve needle against the opening of the valve needle to move the valve needle into a closing relationship with the first set of injection openings; a control piston slidably disposed within the nozzle body and acting on one side of the valve needle; a spring chamber within the nozzle body; inlet means within the nozzle body for applying pressurized control fluid from an associated fluid pressure source on the side of the spring chamber facing the valve needle to the control piston; and means for controlling the control fluid pressure independently of the fuel discharged from the fuel injection nozzle through the first set of injection openings.

[0010] 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.

[0011] 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.

[0012] According to a first aspect, there is provided a fuel valve for injecting liquid fuel into a combustion chamber of a crosshead type large two-stroke turbocharged uniflow scavenged internal combustion engine. The fuel valve includes: A fuel inlet port; A fuel control port; one or more primary nozzle holes; one or more pilot nozzle holes; a valve member displaceable between a closed position and an open position, the valve member having an intermediate position between the closed position and the open position; the valve member is resiliently biased toward the closed position and hydraulically biased toward the open position by fuel pressure at the fuel inlet port acting on a first face of the valve member; the valve member, in the closed position, closes fuel flow to the one or more main nozzle holes and also closes fuel flow to the one or more pilot nozzle holes; the valve member, in the intermediate position, is closed to fuel flow to the one or more main nozzle holes but open to fuel flow to the one or more pilot nozzle holes; the valve member, in the open position, is open to fuel flow to the one or more main nozzle holes and is also open to flow to the one or more pilot nozzle holes; The fuel valve further includes a mechanism for selectively impeding displacement of the valve member from the intermediate position to the open position, the mechanism comprising: a baffle member having a second surface exposed to fuel pressure in the first fuel chamber; an electronically controlled valve having at least a first position and a second position; The electronically controlled valve is preferably a solenoid valve, and the electronically controlled valve further comprises: causing fuel pressure at the fuel inlet port to be provided within the first fuel chamber in the first position; causing fuel pressure at the fuel control port to be provided in the first fuel chamber in the second position; It is configured as follows: the baffle member is displaceable between a blocking position and a non-blocking position, in the blocking position the baffle member obstructs displacement of the valve member from the intermediate position to the open position, and in the non-blocking position the baffle member does not obstruct displacement of the valve member from the intermediate position to the open position, and further wherein the baffle member: to the blocking position when fuel pressure at the fuel inlet port is brought into the first fuel chamber; moving to the unobstructed position when fuel pressure at the fuel control port is brought into the first fuel chamber; It is configured as follows.

[0013] This fuel valve is capable of precisely controlling the pilot and main fuel injection into the combustion chamber of large crosshead type two-stroke turbocharged uniflow scavenged internal combustion engines, thereby ensuring optimal mixture and combustion efficiency, improving engine performance and reducing emissions.

[0014] The arrangement for selectively preventing displacement of the valve member improves control of the fuel injection process. By preventing the transition of the valve member from an intermediate position to a closed position, the fuel valve provides a precise pilot injection (small volume) and ensures precise timing and duration of fuel injection.

[0015] An electronically controlled valve, preferably a solenoid valve, allows for fast and precise switching between a first and second position, i.e., between pilot and main injection, allowing a seamless transition between pilot only and main injection, facilitating efficient fuel injection control.

[0016] The fuel valve uses only fuel as the pressure medium for obtaining the lift of the valve member / valve needle and for the mechanism that opens the valve member to a position where only pilot injection is performed through the small pilot nozzle opening or to a position where injection is also performed through the large main nozzle opening. Since fuel is the only hydraulic medium, there is no risk of another pressure medium, such as hydraulic oil, mixing with the fuel oil. This greatly reduces the need for measures to prevent mixing of fuel and hydraulic oil and greatly simplifies the structure required to provide a barrier between the two pressure media. Furthermore, the fuel valve does not require an external control valve for operation, does not require a double-walled hydraulic pipe for the hydraulic medium, and does not require a hydraulic control block associated with the hydraulic medium. Furthermore, the fuel valve itself does not require internal seals, detection means between the media, and parts specially adapted for the hydraulic oil. Thus, the fuel valve itself is greatly simplified and its installation on the engine is also greatly simplified. Only a cable is required for installation on the engine, and no hydraulic control valve or double-walled pipe for the hydraulic medium is required.

[0017] Resilient biasing of the fuel valve toward the closed position ensures that the valve member remains closed to fuel flow to the main and pilot nozzle holes when not in use, thereby preventing fuel leaks and potential safety hazards.

[0018] Fuel pressure at the fuel inlet port hydraulically biases the valve member toward an open position, providing smooth, controlled opening of the valve, thereby ensuring reliable and consistent fuel flow to the main and pilot nozzle holes during periods of operation.

[0019] The ability of the valve member to open for fuel flow to both the main and pilot nozzle holes in the open position, and to open for fuel flow only through the pilot nozzle hole in the intermediate position, provides flexibility in fuel injection strategies and allows the fuel injector to be used for pilot injection only, which may be convenient, for example, in dual fuel engines where the main fuel is a separate fuel from the pilot fuel, e.g., natural gas, and is delivered to the combustion chamber by a separate fuel valve specifically designed for delivering the main fuel. This allows for optimization of combustion characteristics depending on the engine operating conditions, improving performance and fuel economy.

[0020] In one example implementation of the first approach, the first fuel chamber is permanently connected to the fuel inlet port via a conduit including a flow restriction, and the electronic control valve connects the first fuel chamber to the fuel control port in the second position.

[0021] Fluid connections between the first fuel chamber and the fuel inlet and fuel control ports ensure efficient fuel delivery and control, eliminating the need for additional fuel lines and connections, simplifying the fuel valve design and reducing potential points of failure.

[0022] A permanent connection between the first fuel chamber and the fuel inlet port through a conduit that includes a flow restriction allows the pressure in the first fuel chamber to change to the pressure at the fuel control port by opening the conduit that establishes a fluid connection with the fuel control port because the flow restriction restricts flow from the fuel inlet port to the first fuel chamber such that flow from the fuel inlet port is insufficient to maintain the fuel inlet port pressure in the first fuel chamber.

[0023] The electronically controlled valve is configured to connect the first fuel chamber to the fuel control port in the second position to provide precise control of fuel pressure in the first fuel chamber, thereby allowing the operation of the fuel valve to be modulated for pilot or main injection.

[0024] In one example implementation of the first approach, the electronic control valve connects the first fuel chamber to the fuel inlet port in the first position and connects the first fuel chamber to the fuel control port in the second position.

[0025] The electronically controlled valve is configured to connect the first fuel chamber to the fuel inlet port in the first position, allowing pressure in the first fuel chamber to match pressure in the fuel inlet port such that the baffle member moves to a position where it limits movement of the valve member to the intermediate position and prevents movement to the open position.

[0026] The electronic control valve is configured in the second position to connect the first fuel chamber to the fuel control port, thereby allowing the pressure in the first fuel chamber to match the pressure in the fuel control port, such that the pressure in the first fuel chamber is the same as the pressure in the fuel control port. The pressure in the fuel control port is selected to be different from, and preferably lower than, the pressure in the fuel inlet port. This causes the baffle member to move to a position that does not prevent movement of the valve member to the open position, thereby allowing the main nozzle opening to open.

[0027] A dimensional difference between the first surface of the valve member and the second surface of the baffle member ensures positive movement of the baffle member to the baffle position, thereby preventing the valve member from lifting to an open position when fuel inlet port fuel pressure is present in the first fuel chamber, thereby ensuring pilot injection.

[0028] In one example implementation of the first aspect, a size of the first surface of the valve member is smaller than a size of the second surface of the baffle member.

[0029] The ability of the fuel valve to selectively prevent displacement of the valve member from the intermediate position to the closed position provides control over the operating mode of the fuel valve, i.e., pilot or main injection mode, such that the fuel valve can be used as a pilot fuel valve to assist in ignition of a main fuel provided by a dedicated separate fuel valve, as well as a main fuel valve for liquid fuel. Thus, the fuel valve of the present invention is particularly suitable for use in dual fuel engines, and can be used for both pilot injection of liquid fuel and main injection of liquid fuel.

[0030] Movement of the baffle member to the baffle position when fuel inlet port fuel pressure is provided within the first fuel chamber ensures positive closure of the valve member.

[0031] Movement of the obstruction member to the unobstructed position when fuel control port fuel pressure is provided within the first fuel chamber allows the valve member to shift out of the obstructed condition.

[0032] In one example implementation of the first approach, the baffle member has a plunger that fits snugly within the bore and a third surface opposite the second surface, and the valve member has a fourth surface opposite the first surface and facing the third surface.

[0033] The plunger fits snugly into the baffle member to ensure a positive and reliable baffle position, preventing leakage and unintended movement.

[0034] The arrangement of the third surface of the baffle member and the fourth surface of the valve member provides accurate and stable abutment when the baffle member is in the baffle position and the valve member is in the intermediate position to ensure proper functioning of the valve system.

[0035] The displaceable valve member is unseated from the valve seat in the open and intermediate positions to allow for controlled flow of liquid fuel.

[0036] In one example implementation of the first aspect, when the baffle member is in the baffle position and the valve member is in the intermediate position, the fourth surface abuts the third surface.

[0037] The attachment between the base of the nozzle body and the distal end of the fuel valve provides a secure and stable connection, minimizing the risk of delamination or leakage during operation.

[0038] In one example implementation of the first aspect, the displaceable valve member seats on the valve seat in the closed position and unseats from the valve seat in the open position and the intermediate position.

[0039] The use of a plunger that is closely received in the bore for the baffle member ensures a positive and reliable baffle position, preventing leakage and unintended movement.

[0040] The arrangement of the third surface of the baffle member and the fourth surface of the valve member provides accurate and stable abutment when the baffle member is in the baffle position and the valve member is in the intermediate position to ensure proper function of the fuel valve.

[0041] In one example implementation of the first approach, the nozzle comprises a nozzle body having a region 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 preferably being attached to the distal end of the fuel valve housing.

[0042] The attachment between the base of the nozzle body and the distal end of the fuel valve provides a secure and stable connection, minimizing the risk of delamination or leakage during operation.

[0043] In one embodiment of the first aspect of the implementation, the nozzle body includes: 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 single straight main bore extending longitudinally from said inlet into said nozzle body; has.

[0044] The plunger fits snugly into the baffle member to ensure a positive and reliable baffle position, preventing leakage and unintended movement.

[0045] The arrangement of the third surface of the baffle member and the fourth surface of the valve member provides accurate and stable abutment when the baffle member is in the baffle position and the valve member is in the intermediate position to ensure proper functioning of the valve system.

[0046] In one implementation of the first aspect, the displaceable valve member has a distal portion having a cylindrical end carried by a stem, the cylindrical end fitting snugly within the straight main bore as an axis;

[0047] when the displaceable valve member is in a closed position, fluidly isolating a main nozzle bore and a pilot nozzle bore from the straight main bore;

[0048] when the displaceable valve member is in an intermediate position, fluidly isolating the main nozzle hole from the straight main bore and fluidly connecting the pilot nozzle hole to the straight main bore;

[0049] When the displaceable valve member is in an open position, it fluidly connects the main nozzle bore and the pilot nozzle bore to the straight main bore.

[0050] In one example implementation of the first approach, the cylindrical end is hollow to form a fluid passageway, which preferably opens proximally to the exterior of the handle and opens distally in the axial direction.

[0051] In one example implementation of the first aspect, a cross-sectional area of ​​the pilot nozzle hole is smaller than a cross-sectional area of ​​the main nozzle hole.

[0052] In one example implementation of the first approach, the main nozzle hole and / or the pilot nozzle hole are bores.

[0053] In one example of an implementation of the first approach, the main nozzle hole and the pilot nozzle hole are connected to the main hole at positions axially spaced from each other. This configuration allows for independent adjustment of the main and pilot nozzle holes, providing precise control of fluid flow through the nozzle system. The main and pilot nozzle holes are connected at an axial distance from each other, so that the lift of the valve member determines whether no injection is performed, whether injection is performed only through the pilot nozzle hole, or whether injection is performed through both the pilot and main nozzle holes.

[0054] In one example of an implementation of the first approach, the displaceable valve member has a distal portion with a cylindrical end carried on a stem portion, the cylindrical end fitting snugly within the straight main bore as an axis. The cylindrical end fits snugly into the main bore, ensuring a secure and reliable connection and preventing leakage or loss of fluid during operation. The design also allows for smooth and precise movement of the displaceable valve member, ensuring precise control of fluid through the nozzle system.

[0055] In one example implementation of the first approach, the cylindrical end is hollow to form a fluid passageway, which preferably opens proximally to the exterior of the handle and opens distally in the axial direction. The hollow cylindrical end provides a dedicated fluid passageway allowing efficient and controlled flow of fluid through the nozzle system. By having the fluid passageway open proximally to the exterior of the stem and open axially distally, fluid can be directed precisely to a desired location, improving overall performance and functionality of the nozzle system.

[0056] In one example implementation of the first aspect, a cross-sectional area of ​​the pilot nozzle hole is smaller than a cross-sectional area of ​​the main nozzle hole. This configuration allows for precise control of the small flow of fuel through the nozzle system for pilot injection, since the pilot nozzle holes have a smaller cross-sectional area and therefore a more restricted flow compared to the main nozzle holes. Different cross-sectional areas of the pilot and main nozzle holes allow for selectable fuel flow rates, providing flexibility and versatility in a variety of applications, especially in dual fuel engines.

[0057] In one example of the implementation form of the first aspect, the main nozzle hole and / or the pilot nozzle hole The flow characteristics can be better controlled, allowing the nozzle system to operate more accurately and efficiently.

[0058] In one example of an implementation of the first approach, the main nozzle hole and the pilot nozzle hole are connected to the main hole at positions axially spaced from each other. · By connecting the main nozzle hole and the pilot nozzle hole to the main hole at an axial distance, the magnitude of the fuel flow can be selected for pilot injection and main injection.

[0059] In one example of an implementation of the first approach, the displaceable valve member has a distal portion with a cylindrical end carried on a stem portion, the cylindrical end fitting snugly within the straight main bore as an axis. The cylindrical end fits snugly into the main bore ensuring solid and reliable operation and preventing leakage or loss of fluid during operation. The design also allows for smooth and precise movement of the displaceable valve member, ensuring precise control of fluid through the nozzle system.

[0060] In one example implementation of the first approach, the cylindrical end is hollow to form a fluid passageway, which preferably opens proximally to the exterior of the handle and opens distally in the axial direction. The hollow cylindrical end provides a dedicated fluid passageway allowing efficient and controlled flow of fluid through the nozzle system. By having the fluid passageway open proximally to the exterior of the stem and open axially distally, fluid can be directed precisely where desired.

[0061] In one example implementation of the first aspect, the valve member is a valve needle slidably received within a longitudinal bore of an elongated valve body, the displaceable valve member seated on a valve seat in a closed position and the valve needle unseated from the valve seat in an open position and an intermediate position. By using a valve needle as the valve member, the amount of lift from the valve seat between the open position and the intermediate position can be easily adjusted, thereby enabling accurate control of the fuel flow rate within the engine. By locating the valve seat and / or fuel chamber within an elongated valve body, the overall size and complexity of the fuel injection system can be reduced, resulting in lower manufacturing and maintenance costs.

[0062] By having all of the multiple main nozzle holes having substantially equal major cross-sectional areas or diameters, and preferably substantially equal lengths, uniform fuel flow distribution throughout the multiple nozzle holes is achieved, improving engine performance and efficiency.

[0063] In one example implementation of the first aspect, the valve seat and / or the fuel chamber are disposed within an elongated valve body.

[0064] In one implementation of the first aspect, the plurality of primary nozzle holes all have substantially equal main cross-sectional areas or diameters, and preferably have substantially equal lengths.

[0065] In one example of an implementation form of the first aspect, the main nozzle hole and / or the pilot nozzle hole opens into a surface of an elongated (preferably cylindrical) portion.

[0066] In one example implementation of the first aspect, the electronically controlled valve is a spool valve, preferably a sliding spool valve, and more preferably a sliding spool solenoid valve.

[0067] In one implementation of the first aspect, the fuel valve has a preferably rounded transition surface between the cylindrical portion and a flat distal end surface of the nozzle body.

[0068] In one example implementation of the first aspect, the plurality of straight nozzle holes each have a nozzle axis, and the nozzle axis of each nozzle hole is disposed at an obtuse angle α with respect to a main direction X.

[0069] In one example implementation of the first approach, each radial component of the nozzle axis relative to the longitudinal axis X is distributed over a sector having an arc of less than 120 degrees, preferably substantially evenly distributed.

[0070] 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.

[0071] The above and other aspects of the present invention will become more apparent from the embodiments described below. [Brief description of the drawings]

[0072] 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] Figure 4 is a cross-sectional view of an embodiment of a fuel valve for use in the engine of Figures 1 to 3, shown prior to a fuel injection event with the valve member in a closed position; [Diagram 5]5 is a cross-sectional view of the fuel valve of Figure 4 during a fuel injection event, with the valve member in an open position and the baffle member in a non-baffle position. [Figure 6] FIG. 5 is a cross-sectional view showing in more detail the nozzle of the fuel valve in the state shown in FIG. 4. [Figure 7] FIG. 6 is a cross-sectional view showing in more detail the nozzle of the fuel valve in the state shown in FIG. 5. [Figure 8] 5 illustrates the fuel valve of FIG 4 prior to a fuel injection event, with the valve member in a closed position. [Figure 9] 5 is a cross-sectional view of the fuel valve of Figure 4 during a fuel injection event, with the valve member in an open position and the baffle member in a baffle position. [Figure 10] FIG. 9 is a cross-sectional view showing in more detail the nozzle of the fuel valve in the state shown in FIG. 8. [Figure 11] FIG. 10 is a cross-sectional view showing in more detail the nozzle of the fuel valve in the state shown in FIG. 9. [Figure 12] FIG. 5 is a schematic view of a nozzle tip portion of the fuel valve of FIG. [Figure 13] FIG. 13 is a perspective view of the nozzle tip of FIG. 12. [Figure 14] FIG. 13 is a perspective view of the nozzle tip of FIG. 12. [Figure 15] FIG. 5 is a view from the piston side of the nozzle location of the fuel valve of FIG. 4 located in the cylinder cover of the engine, showing the nozzle hole orientation and the resulting fuel jet. Detailed explanation

[0073] 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.

[0074] 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 the cylinder cover 26. Following the injection of the fuel, combustion occurs and exhaust is generated. 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 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.

[0075] 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.

[0076] 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 spacer frame 24.

[0077] FIG. 15 illustrates how the nozzles 40 are arranged on the periphery of the cylinder cover 26 around the exhaust valve 4. FIG. 15 also illustrates the direction of fuel injection, which corresponds to the direction of the axes I, II, III, IV, V of the main nozzle holes 45 of the nozzle 40. Typically, at least four main nozzle holes 45 and one or two pilot nozzle holes 46 are provided. The fuel ejection direction of the pilot nozzle holes 46 is similar to that of the main nozzle holes 45. Usually, three (as shown) or four fuel valves 30 are provided for each cylinder. In a dual fuel engine, three or four other fuel valves are provided (not shown) for injecting another fuel. When the other fuel valve is activated, the fuel valve 30 is used only for pilot fuel injection. When the other fuel is not used, the fuel valve 30 is used for main fuel injection. The swirl direction of the gases in the combustion chamber is illustrated by the curved dashed arrows 96. The cross-sectional area of ​​the pilot nozzle holes 46 is smaller than the cross-sectional area of ​​the main nozzle holes 45, and the number of pilot nozzle holes 46 is typically smaller than the number of main nozzle holes 45. Thus, the amount of fuel injected through only the pilot nozzle holes 46 at a given fuel injection pressure is significantly less than the amount of fuel injected through the pilot nozzle holes 46 and the main nozzle holes 45 combined. Preferably, all of the main nozzle holes 45 have substantially equal cross-sectional areas or diameters, and preferably have substantially equal lengths. Preferably, all of the pilot nozzle holes 46 also have substantially equal cross-sectional areas or diameters, and preferably have substantially equal lengths. The cross-sectional area or diameter of the main nozzle holes 45 is larger than the cross-sectional area or diameter of the pilot nozzle holes 46.

[0078] 4 through 11 show one embodiment of two to four fuel valves 30 mounted within a through bore in the cylinder cover 26 of each cylinder. The fuel valve 30 is 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 the nozzle 40 protruding slightly into the combustion chamber.

[0079] 12-14 show the distal end of nozzle 40 in greater detail.

[0080] The fuel valve 30 has an elongated fuel valve body 32 having a nozzle 40 at its distal end 33. 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 has an elongated body 32 having 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. The fuel pump increases the fuel pressure at the start of fuel injection and decreases the pressure at the end of fuel injection. A typical maximum fuel injection pressure is greater than 200 bar, preferably greater than 300 bar.

[0081] The head of the proximal end 31 has a fuel inlet 83. The fuel inlet port 83 is in fluid communication with a duct extending through the valve body 32. An axially displaceable valve member 35 (preferably a valve needle) is journalled within the valve housing 32 and has an open position in which the valve member 35 is unseated from a (preferably conical) valve seat 36, an intermediate position in which the valve member 35 is also unseated from the valve seat 36, and a closed position in which the valve member 35 (a portion of the valve member 35 corresponding to the valve seat 36) is seated on the valve seat 36 to close the valve. The valve needle is resiliently biased towards the closed position by elastic means formed in this embodiment by a helical spring 87. Pressure of fuel supplied to the fuel inlet port 83 acts on a first face of the valve member 35 causing the valve needle 35 to lift against the bias of the helical spring 87. In this embodiment, pressure within the second fuel chamber 68 acts on a first face of the valve member 35 urging the valve member 35 towards the open position.

[0082] The fuel valve 30 carries a nozzle 40 at its distal end 33. The nozzle 40 is configured to project into the combustion chamber 14 of the engine cylinder liner 1 through five nozzle holes 46, or through both a pilot nozzle hole 46 and a main nozzle hole 45.

[0083] In this embodiment, the fuel valve 30 has a valve member 35 in the form of a valve needle. The valve member 35 has a conical portion which cooperates with a conical valve seat 36 in the elongated body 32 of the fuel valve 30. The valve seat 36 opens into a second fuel chamber 68. The second fuel chamber 68 surrounds an axial portion of the valve member 35 and houses a helical spring 87. A fuel duct 62 connects a fuel inlet port 83 to the second fuel chamber 68.

[0084] A fuel control port 85 opening into the body surface of the fuel valve 30, preferably near its aft or proximal end, receives a reference or control fuel pressure (by connection to a source of substantially constant fuel pressure).

[0085] In this embodiment, the control fuel pressure is less than the pressure of fuel delivered to fuel inlet port 83 during a fuel injection event. Fuel control port 85 is connected to first fuel chamber 81 through electronically controlled valve 60. Electronically controlled valve 60 is preferably a solenoid valve having at least two positions, open or closed, and is controlled by the engine's electronic control unit (not shown). Electronically controlled valve 60 is preferably a spool valve, preferably a sliding spool valve, and more preferably a sliding spool solenoid valve.

[0086] The first fuel chamber 81 is connected to a fuel inlet port 83 by a duct 67. The duct 67 has a flow restriction 64. The flow restriction 64 has an orifice or other suitable shape. The flow restriction 64 allows a relatively small flow of fuel from the fuel inlet port 83 to the first fuel chamber 81 compared to the flow of fuel from the fuel control port 85 to the first fuel chamber 81 when the electronic control valve 60 is in an open position. The displaceable baffle member 80 has the shape of a plunger. The baffle member 80 fits snugly within a bore in the valve body 32 so as to be axially displaceable between a blocking position and a non-blocking position. The first fuel chamber 81 is formed within the bore of the valve body, and the baffle member has a second (axially facing) face exposed to fuel pressure in the first fuel chamber 81.

[0087] The baffle member 80 has a reduced diameter portion opposite the second surface to limit the stroke in the direction toward the nozzle 40. The reduced diameter portion is received in a corresponding bore in the valve body 32. The reduced diameter portion has a third surface opposite the second surface. The proximal-most portion of the valve member 35 has a fourth surface opposite the first surface and facing the third surface. The size of the first surface of the valve member 35 is smaller than the size of the third surface of the baffle member 80, so that when the first surface and the third surface are subjected to equal pressure, the force of the baffle member 80 in the closing direction is greater than the force of the valve member 35 in the opening direction. As shown in FIG. 9, when the baffle member 80 is in the baffle position and the valve member 35 is in the intermediate position, the fourth surface contacts the third surface, thereby preventing the valve member 35 from moving from the intermediate position to the open position.

[0088] The electronic control valve 60 is configured such that in its closed position, the fuel pressure at the fuel inlet port 83 is provided to the first fuel chamber 81, and in its open position, the fuel pressure at the fuel control port 85 is provided to the first fuel chamber 81. The baffle member 80 is displaceable between a baffle position and a non-baffle position. In the baffle position, the baffle member 80 prevents the valve member 35 from moving from the intermediate position to the open position, and in the non-baffle position, the baffle member 80 does not prevent the valve member 35 from moving from the intermediate position to the open position. The baffle member 80 moves to the baffle position shown in FIG. 9 when the fuel pressure at the fuel inlet port 83 is developed in the first fuel chamber 81, i.e., when the electronic control valve 60 is open, and is free to move to the non-baffle position when the fuel pressure at the fuel control port 85 is developed in the first fuel chamber 81, i.e., when the electronic control valve 60 is closed. The fourth surface abuts against the third surface, thereby preventing the valve member 35 from moving further in the direction toward the open position.

[0089] 12 to 14 show the nozzle 40 and the distal portion of the valve needle 35 in greater detail.

[0090] The nozzle 40 has a nozzle body extending along a longitudinal axis (X) from a base 42 at a proximal end 41 to a closed distal end 44 which 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, as known in the art.

[0091] 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 intermediate or open position. A straight main bore 50 extends longitudinally into the nozzle body from the inlet 48. The closed distal end 44 has a substantially planar end face 47 having a circular or elliptical profile. The end face 47 is connected to a cylindrical portion via a curved or rounded transition surface 49.

[0092] The nozzle 40 has a plurality of main nozzle holes 45 (typically 3 to 7 main nozzle holes 45), preferably straight main nozzle holes, and one or more pilot nozzle holes 46 (typically two pilot nozzle holes 46), preferably straight pilot nozzle holes 46.

[0093] The multiple main nozzle holes 45 open into the outer surface of the nozzle body 43 at different radial angles, and when the fuel valve 30 is in an open state, a fan-shaped fuel jet is generated in the combustion chamber as shown in Fig. 14. The main nozzle holes 45 open into the outer surface of the nozzle body 43 at different radial angles. Preferably, the main nozzle holes 45 open into the cylindrical surface 43 and / or the transition surface 49. Similarly, the pilot nozzle holes 46 open into the cylindrical surface 43 and / or the transition surface 49 at an appropriate radial angle.

[0094] The base 42 has an inlet port 48 for receiving fuel from the fuel valve body 32. 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 near the distal end 44 of the nozzle body. The main bore 50 connects to the main nozzle bore 45 at a first axial distance from the distal end 44 and connects to the pilot nozzle bore 46 at a second axial distance from the distal end 44. The second axial distance is less than the first axial distance. Thus, flow from the main bore 50 to the pilot nozzle bore 46 is possible with a smaller lift (less axial displacement) of the valve member 35 toward the open position, and flow from the main bore 50 to the main nozzle bore 46 is possible only with a larger lift (more axial displacement) of the valve member 35 toward the open position. This difference in lift of the valve member 35 and its cylindrical portion 39 is indicated by the long double arrow in FIG. 13 and the short double arrow in FIG. 14. FIG. 13 shows the valve member 35 in an open position, and FIG. 14 shows the valve member 35 in an intermediate position.

[0095] The valve needle 35 comprises a distal portion having a cylindrical end 39 carried on a stem 38. 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 axially distally.

[0096] 4, 6 and 10, when the valve needle 35 is in the closed position, the cylindrical end 39 fits snugly and axially into the straight main bore 50 to fluidly isolate the pilot nozzle hole 46 and the main nozzle hole 45 from the main bore 50. As depicted in Figures 4, 6 and 10, when the valve needle 35 is in the closed position, the cylindrical end 39 covers the openings of the pilot nozzle hole 46 and the main nozzle hole 45 to 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 member 35 is in the closed position.

[0097] In the intermediate position of the valve member 35, lift or axial movement of the valve member to the open position merely causes the cylindrical portion 39 to cover the opening to the main nozzle hole 45, thereby allowing fuel to be injected into the combustion chamber through the pilot nozzle hole 46 but not through the main nozzle hole 45, as shown in Figures 9 and 11.

[0098] 5 and 7, when the valve member 35 is in the open position, the cylindrical end 39 connects the openings of both the pilot nozzle hole 46 and the main nozzle hole 45 to the straight main hole 50, as neither of the openings of the pilot nozzle hole 46 nor the main nozzle hole 45 blocks the straight main hole 50. This allows fuel to be injected into the combustion chamber through both the pilot nozzle hole 46 and the main nozzle hole 45 (main injection event).

[0099] In one embodiment of the fuel valve 30, not shown, the electronic control valve 60 in a first position connects the first fuel chamber 81 to the fuel inlet port 83 and in a second position connects the first fuel chamber 81 to the fuel control port 85, without requiring a restriction in the fluid connection between the fuel inlet port and the first pressure chamber.

[0100] 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 combustion chamber of a crosshead type large two-stroke turbocharged uniflow scavenging internal combustion engine, comprising: a fuel inlet port; a fuel control port; one or more primary nozzle holes; one or more pilot nozzle holes; a valve member displaceable between a closed position and an open position, the valve member having intermediate positions between the closed and open positions; the valve member is resiliently biased toward the closed position and hydraulically biased toward the open position by fuel pressure at the fuel inlet port acting on a first face of the valve member; the valve member, in the closed position, closes against fuel flow to the one or more main nozzle holes and also closes against fuel flow to the one or more pilot nozzle holes; the valve member, in the intermediate position, is closed to fuel flow to the one or more main nozzle holes but open to fuel flow to the one or more pilot nozzle holes; the valve member, in the open position, is open to fuel flow to the one or more main nozzle holes and is also open to flow to the one or more pilot nozzle holes; The fuel valve further includes a mechanism for selectively impeding displacement of the valve member from the intermediate position to the open position, the mechanism comprising: a baffle member having a second surface exposed to fuel pressure in the first fuel chamber; an electronically controlled valve having at least a first position and a second position; The electronically controlled valve is preferably a solenoid valve, and the electronically controlled valve further comprises: causing fuel pressure at the fuel inlet port to be provided within the first fuel chamber in the first position; causing fuel pressure at the fuel control port to be provided in the first fuel chamber in the second position; It is configured as follows: the baffle member is displaceable between a blocking position and a non-blocking position, in the blocking position the baffle member obstructs displacement of the valve member from the intermediate position to the open position, and in the non-blocking position the baffle member does not obstruct displacement of the valve member from the intermediate position to the open position, and further wherein the baffle member: moving to the blocking position when fuel pressure at the fuel inlet port is provided into the first fuel chamber; moving to the unobstructed position when fuel pressure at the fuel control port is provided within the first fuel chamber; It is configured as follows: Fuel valve.

2. The fuel valve of claim 1 , wherein the first fuel chamber is fluidly connected to the fuel inlet port and the fuel control port.

3. 2. The fuel valve of claim 1, wherein the first fuel chamber is permanently connected to the fuel inlet port through a conduit including a flow restriction, and the electronically controlled valve connects the first fuel chamber to the fuel control port in the second position.

4. 2. The fuel valve of claim 1, wherein the electronically controlled valve in the first position connects the first fuel chamber to the fuel inlet port and in the second position connects the first fuel chamber to the fuel control port.

5. 2. The fuel valve of claim 1, wherein the first surface of the valve member is smaller in size than the second surface of the baffle member.

6. 2. The fuel valve of claim 1, wherein the baffle member has a plunger that fits snugly within the bore and a third surface opposite the second surface, and the valve member has a fourth surface opposite the first surface and opposing the third surface.

7. 7. The fuel valve of claim 6, wherein the fourth surface abuts the third surface when the baffle member is in the baffle position and the valve member is in the intermediate position.

8. The fuel valve of claim 7 , wherein the displaceable valve member seats on a valve seat in the closed position and unseats from the valve seat in the open position and the intermediate position.

9. an elongated fuel valve body having a longitudinal axis, the fuel valve body having a proximal end and a distal end; The fuel valve of claim 1 , wherein the one or more main nozzle holes and the one or more pilot nozzle holes are disposed in a nozzle, the nozzle being disposed at the distal end.

10. 10. The fuel valve of claim 9, wherein 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 distal end of the fuel valve.

11. 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, the inlet opening into the base; a single straight main bore extending longitudinally from said inlet into said nozzle body; The fuel valve of claim 10, comprising:

12. 12. The fuel valve of claim 11, wherein the main nozzle hole and the pilot nozzle hole are connected to the main hole at positions axially spaced from one another.

13. the displaceable valve member having a distal portion with a cylindrical end carried on a stem, the cylindrical end fitting snugly within the straight main bore as an axis; when the displaceable valve member is in a closed position, fluidly isolating a main nozzle bore and a pilot nozzle bore from the straight main bore; when the displaceable valve member is in an intermediate position, fluidly isolating the main nozzle hole from the straight main bore and fluidly connecting the pilot nozzle hole to the straight main bore; when the displaceable valve member is in an open position, fluidly connecting the main nozzle bore and the pilot nozzle bore to the straight main bore; 12. The fuel valve of claim 11.

14. the cylindrical end being hollow to define a fluid passageway; The fluid passage opens proximally relative to the exterior of the stem and opens axially distally.

14. The fuel valve of claim 13.

15. 2. The fuel valve of claim 1, wherein the pilot nozzle hole has a cross-sectional area smaller than a cross-sectional area of ​​the main nozzle hole.

16. The fuel valve of claim 1 , wherein the main nozzle hole and / or the pilot nozzle hole are bores.

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

18. 18. The fuel valve of claim 17, further comprising a second fuel chamber surrounding an axial portion of the valve member and opening to the valve seat.

19. 20. The fuel valve of claim 18, wherein the valve seat and / or the second fuel chamber are disposed within the elongated valve body.

20. The fuel valve of claim 1 , wherein the plurality of primary nozzle holes all have the same cross-sectional area or diameter.

21. A fuel valve as described in claim 1, wherein the plurality of main nozzle holes all have equal length.

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

23. The fuel valve of claim 1, wherein the plurality of pilot nozzle holes all have equal length.

24. 21. The fuel valve of claim 20, wherein the main nozzle hole has a cross-sectional area or diameter greater than the cross-sectional area or diameter of the pilot nozzle hole.

25. 2. The fuel valve according to claim 1, wherein the main nozzle hole and / or the pilot nozzle hole open into a surface of an elongated, preferably cylindrical, portion.

26. 2. The fuel valve of claim 1, wherein the electronically controlled valve is a spool valve, preferably a sliding spool valve, more preferably a sliding spool solenoid valve.

27. A crosshead type large two-stroke turbocharged uniflow scavenging internal combustion engine comprising a fuel valve according to any one of claims 1 to 26.

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