JP7737524B2 - 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 subject matter disclosed in this application (hereinafter referred to as "the present disclosure") relates to a fuel valve for injecting liquid fuel into the cylinders of a large turbocharged, two-stroke, uniflow-scavenged internal combustion engine, and an engine equipped with such a fuel valve.

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 a nozzle body with a cylindrical section containing 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 (because the top surface of the piston is very close to the tip of the nozzle when the piston is at top dead center, i.e., at the moment of fuel injection in a compression-ignition engine). Typically, each nozzle has three to seven nozzle holes, all connected to the main holes. Fuel valves capable of both main and pilot injection typically also have one or two small pilot nozzle holes connected to the main holes. These valves typically have a displaceable valve member such that only the pilot nozzle hole is open when the valve member lift is small, and both the pilot and main nozzle holes are open when the valve member lift is large.

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 cylinder 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 such a slide valve structure, residual fuel within the main bore (and nozzle bore) would drip into the combustion chamber after fuel injection ends, adversely affecting fuel consumption, reliability, and emissions.

Patent document 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 section having a single valve needle that is elastically supported by the valve body and moves 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 section is determined by a pressing force applied within the valve body. The valve needle simultaneously opens the main injection hole and the pilot injection hole when the fuel supply mode is diesel mode, and opens only the pilot injection hole when the fuel supply mode is gas mode. To limit the stroke to pilot injection only, high-pressure hydraulic oil is applied to a displaceable closure plunger provided in the fuel valve. Therefore, this known fuel valve requires connection to a high-pressure hydraulic system in addition to connection to the fuel supply system. Therefore, the engine must be equipped with such a hydraulic system. Each of the three or four fuel valves of a cylinder must be connected to the high-pressure hydraulic system via double-walled piping, and each fuel valve must be connected to a valve block having a hydraulic valve capable of handling high-pressure hydraulic oil. This valve must be designed to prevent hydraulic oil from mixing with the fuel, and vice versa, so the fuel valve must be fitted with anti-contamination measures such as seals and pressure barriers. These requirements make the fuel valve expensive, the engine expensive due to the additional equipment required, and unreliable as there is always a risk of fuel and hydraulic oil mixing.

US Pat. No. 4,285,471A discloses a fuel injection nozzle for an internal combustion engine. The fuel injection nozzle comprises: 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 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 to the control piston from an associated fluid pressure source on the side of the spring chamber facing the valve needle; and means for controlling the control fluid pressure independently of fuel discharged from the fuel injection nozzle through the first set of injection openings.

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 combustion chamber of a crosshead type large two-stroke turbocharged uniflow scavenged internal combustion engine. The fuel valve comprises:
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 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 surface 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 also to fuel 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 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 the baffle member:
moving to the obstructing 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.

This fuel valve can precisely control the pilot and main fuel injection into the combustion chambers of large, crosshead, two-stroke, turbocharged, uniflow-scavenged internal combustion engines. This ensures optimal mixture and combustion efficiency, resulting in improved engine performance and reduced emissions.

The selectively impeding valve member displacement improves control of the fuel injection process. By preventing the valve member from transitioning from an intermediate position to a closed position, the fuel valve delivers a precise pilot injection (small volume) and ensures precise timing and duration of fuel injection.

An electronically controlled valve, preferably a solenoid valve, allows for fast and accurate switching between the first and second positions, i.e., between pilot and main injection. This allows for a seamless transition between pilot-only and main injection, facilitating efficient fuel injection control.

This fuel valve uses only fuel as the pressure medium for obtaining lift for 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 where injection is also performed through the large main nozzle opening. Because fuel is the only hydraulic medium, there is no risk of another pressure medium, such as hydraulic oil, mixing with the fuel oil. This significantly reduces the need for measures to prevent fuel and hydraulic oil mixing and greatly simplifies the structure required to provide a barrier between the two pressure media. Furthermore, this fuel valve does not require an external control valve for operation, does not require double-walled hydraulic piping 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, inter-medium detection means, or components specifically adapted for the hydraulic oil. Therefore, not only is the fuel valve itself significantly simplified, but its installation on the engine is also significantly simplified. Only a cable is required for installation on the engine; no hydraulic control valve or double-walled piping for the hydraulic medium is required.

Resiliently biasing 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, preventing fuel leaks and potential safety hazards.

Fuel pressure at the fuel inlet port hydraulically biases the valve member toward the open position, allowing for smooth, controlled opening of the valve. This ensures reliable and consistent fuel flow to the main and pilot nozzle holes throughout operation.

The ability of the valve member to open for fuel flow to both the main and pilot nozzle holes in the open position, and for fuel flow through only 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. This can be useful, for example, in dual-fuel engines where the main fuel is a different fuel from the pilot fuel, such as natural gas, and is supplied to the combustion chamber by a separate fuel valve specifically designed for supplying the main fuel. This allows optimization of combustion characteristics according to the engine's operating conditions, improving performance and fuel economy.

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.

The fluid connection between the first fuel chamber and the fuel inlet and control ports ensures efficient fuel delivery and control. This eliminates the need for additional fuel lines and connections, simplifying the fuel valve design and reducing potential points of failure.

Permanently connecting the first fuel chamber and the fuel inlet port through a conduit containing a flow restriction allows the pressure in the first fuel chamber to be changed to the pressure at the fuel control port. This is possible 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, flow from the fuel inlet port is insufficient to maintain the fuel inlet port pressure within the first fuel chamber.

The electronic control valve is configured to connect the first fuel chamber to the fuel control port in the second position, thereby enabling precise control of fuel pressure in the first fuel chamber. This allows the operation of the fuel valve to be adjusted for pilot or main injection.

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.

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

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

The dimensional difference between the first surface of the valve member and the second surface of the baffle member ensures reliable movement of the baffle member to the baffle position. This prevents the valve member from lifting to the open position when fuel pressure from the fuel inlet port is present in the first fuel chamber, ensuring pilot injection.

In one example implementation of the first concept, the size of the first surface of the valve member is smaller than the size of the second surface of the baffle member.

The ability of the fuel valve to selectively prevent displacement of the valve member from the intermediate position to the closed position allows control of the operating mode of the fuel valve, i.e., pilot injection mode or main injection mode. This allows the fuel valve to be used not only as a pilot fuel valve to assist in ignition of a main fuel supplied by a dedicated separate fuel valve, but also as a main fuel valve for liquid fuel. Therefore, 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.

The movement of the baffle member to the baffle position when fuel pressure at the fuel inlet port is brought into the first fuel chamber ensures reliable closure of the valve member.

When fuel pressure at the fuel control port is brought into the first fuel chamber, the obstruction member moves to the unobstructed position, allowing the valve member to displace out of the obstructed state.

In one example implementation of the first concept, 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 located opposite the first surface and facing the third surface.

The plunger fits snugly into the baffle member, ensuring a secure and reliable baffle position and preventing leakage and unintended movement.

The arrangement of the third surface of the baffle member and the fourth surface of the valve member allows for accurate and stable abutment when the baffle member is in the baffle position and the valve member is in the intermediate position, ensuring proper function of the valve system.

The displaceable valve member is lifted off the valve seat in the open position and the intermediate position, allowing the flow of liquid fuel to be controlled.

In one example implementation of the first concept, 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.

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.

In one example implementation of the first concept, the displaceable valve member is seated on the valve seat in the closed position and is unseated from the valve seat in the open position and the intermediate position.

By using a plunger that is tightly received in the bore for the baffle member, a secure and reliable baffle position is ensured, preventing leakage and unintended movement.

The arrangement of the third surface of the baffle member and the fourth surface of the valve member allows for accurate and stable contact when the baffle member is in the baffle position and the valve member is in the intermediate position, ensuring proper function of the fuel valve.

In one example implementation of the first aspect, the nozzle includes a nozzle body having a region along the longitudinal axis extending from a base at the 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.

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.

In one example of the first implementation, the nozzle body includes:
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 single straight main bore extending longitudinally from said inlet into said nozzle body;
It has.

The plunger fits snugly into the baffle member, ensuring a secure and reliable baffle position and preventing leakage and unintended movement.

The arrangement of the third surface of the baffle member and the fourth surface of the valve member allows for accurate and stable abutment when the baffle member is in the baffle position and the valve member is in the intermediate position, ensuring proper function of the valve system.

In one example of the first implementation, the displaceable valve member has a distal portion with a cylindrical end supported on a stem, and the cylindrical end fits snugly within the straight main bore as an axis.

When the displaceable valve member is in the closed position, it fluidly isolates the main nozzle bore and the pilot nozzle bore from the straight main bore,

When the displaceable valve member is in an intermediate position, the main nozzle bore is fluidly disconnected from the straight main bore and the pilot nozzle bore is fluidly connected to the straight main bore;

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

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

In one example implementation of the first concept, the cross-sectional area of the pilot nozzle hole is smaller than the cross-sectional area of the main nozzle hole.

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

In one example of an implementation of the first aspect, the main nozzle hole and the pilot nozzle hole are connected to the main hole at positions spaced apart from each other in the axial direction.
This configuration allows for independent adjustment of the main and pilot nozzle holes, allowing for precise control of fluid flow through the nozzle system.
By connecting the main nozzle hole and the pilot nozzle hole with an axial gap between them, the lift amount 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 nozzle hole and the main nozzle hole.

In one example of an implementation of the first concept, the displaceable valve member has a distal portion with a cylindrical end carried by 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.

In one example of an implementation of the first approach, the cylindrical end is hollow to form a fluid passage, which preferably opens proximally to the exterior of the handle and axially distally.
- The hollow cylindrical end provides a dedicated fluid passageway that allows for efficient and controlled flow of fluid through the nozzle system.
By opening the fluid passageway proximally to the exterior of the stem and axially opening distally, fluid can be directed precisely to the desired location, improving the overall performance and functionality of the nozzle system.

In one example of an implementation of the first aspect, the cross-sectional area of the pilot nozzle hole is smaller than the 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, as the pilot nozzle holes have a smaller cross-sectional area which restricts the 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, particularly in dual-fuel engines.

In one implementation of the first approach, the main nozzle hole and/or the pilot nozzle hole may provide better control over flow characteristics, allowing the nozzle system to operate more accurately and efficiently.

In one example of an implementation of the first aspect, the main nozzle hole and the pilot nozzle hole are connected to the main hole at positions spaced apart from each other in the axial direction.
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.

In one example of an implementation of the first concept, the displaceable valve member has a distal portion with a cylindrical end carried by 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 positive 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.

In one example of an implementation of the first approach, the cylindrical end is hollow to form a fluid passage, which preferably opens proximally to the exterior of the handle and axially distally.
- The hollow cylindrical end provides a dedicated fluid passageway that allows for efficient and controlled flow of fluid through the nozzle system.
By opening the fluid passageway proximally to the exterior of the stem and axially opening distally, fluid can be directed precisely where desired.

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 lift amount from the valve seat can be easily adjusted between the open position and the intermediate position, thereby enabling accurate control of the fuel flow rate within the engine.
Locating the valve seat and/or fuel chamber within the elongated valve body reduces the overall size and complexity of the fuel injection system, leading to lower manufacturing and maintenance costs.

By ensuring that all of the multiple main nozzle holes have substantially equal main cross-sectional areas or diameters, and preferably substantially equal lengths, uniform fuel flow distribution across the multiple nozzle holes is achieved, improving engine performance and efficiency.

In one example implementation of the first concept, the valve seat and/or the fuel chamber are disposed within a vertically elongated valve body.

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

In one example implementation of the first concept, the main nozzle hole and/or the pilot nozzle hole open onto the surface of a vertically elongated (preferably cylindrical) portion.

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

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

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

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 distributed substantially evenly.

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.

The above and other aspects of the present invention will become more apparent from the embodiments 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. 4 is a cross-sectional view of one embodiment of a fuel valve used in the engine of Figures 1-3, shown prior to a fuel injection event with the valve member in a closed position. Figure 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. 5 is a cross-sectional view showing the nozzle of the fuel valve in more detail in the state of FIG. 4; FIG. 6 is a cross-sectional view showing the nozzle of the fuel valve in more detail in the state of FIG. 5; FIG. 5 illustrates the fuel valve of FIG. 4 prior to a fuel injection event, with the valve member in a closed position. Figure 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. 9 is a cross-sectional view showing the nozzle of the fuel valve in more detail in the state of FIG. 8; 10 is a cross-sectional view showing the nozzle of the fuel valve in more detail in the state of FIG. 9; FIG. FIG. 5 is a schematic view of the nozzle tip of the fuel valve of FIG. 4 . FIG. 13 is a perspective view of the nozzle tip of FIG. 12. FIG. 13 is a perspective view of the nozzle tip of FIG. 12. 5 is a view from the piston side of the nozzle position 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

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. Following fuel injection, combustion occurs and exhaust gas is generated. When the exhaust valve 4 opens, exhaust gas flows 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 gas is 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.

Figure 15 illustrates how the nozzles 40 are arranged around the exhaust valve 4 at the edge of the cylinder cover 26. Figure 15 also illustrates the direction of fuel injection. The direction of fuel injection corresponds to the axes I, II, III, IV, and 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 injection direction of the pilot nozzle holes 46 is the same as that of the main nozzle holes 45. Usually, three (as shown) or four fuel valves 30 are provided for each cylinder. In dual-fuel engines, three or four additional fuel valves 30 are provided (not shown) for injecting additional fuels. When the additional fuel valves are activated, the aforementioned fuel valves 30 are used only for pilot fuel injection. When the additional fuel is not being used, the fuel valves 30 are used for main fuel injection. The swirl direction of gas within 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. Therefore, at a given fuel injection pressure, the amount of fuel injected through the pilot nozzle holes 46 alone 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 the same cross-sectional area or diameter, and preferably also have substantially the same length. Preferably, all of the pilot nozzle holes 46 also have substantially the same cross-sectional area or diameter, and preferably also have substantially the same length. 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.

Figures 4 to 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 valves 30 are mounted within the through bore of the cylinder cover 26 with their rear ends 31 protruding from the top side of the cylinder cover 26 and with the distal ends (tip ends) of the nozzles 40 protruding slightly into the combustion chamber.

Figures 12 to 14 show the distal end of the nozzle 40 in more detail.

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 that may mount the fuel valve 30 to the cylinder cover 26 (in a known manner) and may connect the fuel valve 30 to a fuel pump (not shown) of the internal combustion engine. The fuel pump increases fuel pressure at the start of fuel injection and decreases the pressure at the end of fuel injection. Typical maximum fuel injection pressures are 200 bar or greater, and preferably 300 bar or greater.

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 journaled within the valve housing 32 and has three positions: an open position in which the valve member 35 is clear of a (preferably conical) valve seat 36; an intermediate position in which the valve member 35 is also clear of 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) seats on the valve seat 36 to close the valve. The valve needle is resiliently biased toward the closed position by elastic means, which in this embodiment is formed by a helical spring 87. When pressure from fuel supplied to the fuel inlet port 83 acts on a first face of the valve member 35, the valve needle 35 lifts against the bias of the helical spring 87. In this embodiment, pressure within the second fuel chamber 68 acts on the first face of the valve member 35, urging the valve member 35 toward the open position.

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 through five nozzle holes 46, or through both the pilot nozzle hole 46 and the main nozzle hole 45.

In this embodiment, the fuel valve 30 has a valve member 35 in the shape of a valve needle. The valve member 35 has a conical portion that cooperates with a conical valve seat 36 within 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 the 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.

The fuel control port 85, which opens into the body surface of the fuel valve 30, preferably near its rearmost or proximal end, receives a reference fuel pressure or a control fuel pressure (by connecting it to a source of substantially constant fuel pressure).

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

The first fuel chamber 81 is connected to the 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 fuel flow from the fuel inlet port 83 to the first fuel chamber 81 compared to the fuel flow from the fuel control port 85 to the first fuel chamber 81 when the electronic control valve 60 is in the open position. The displaceable baffle member 80 has the shape of a plunger. The baffle member 80 fits snugly within the bore of the valve body 32 so that it can be displaced axially between an obstructed position and an unobstructed position. The first fuel chamber 81 is formed within the bore of the valve body, and the baffle member has a second (axially facing) surface exposed to fuel pressure within the first fuel chamber 81.

The baffle member 80 has a reduced diameter portion opposite the second surface to limit stroke 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. Because 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, when the first and third surfaces are subjected to equal pressure, the force acting on the baffle member 80 in the closing direction is greater than the force acting on 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 movement of the valve member 35 from the intermediate position to the open position.

The electronic control valve 60 is configured such that, in its closed position, fuel pressure from the fuel inlet port 83 is applied to the first fuel chamber 81, and in its open position, fuel pressure from the fuel control port 85 is applied to the first fuel chamber 81. The baffle member 80 is movable 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. 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 fuel pressure from the fuel inlet port 83 is applied to the first fuel chamber 81, i.e., when the electronic control valve 60 is open. When fuel pressure from the fuel control port 85 is applied to the first fuel chamber 81, i.e., when the electronic control valve 60 is closed, the baffle member 80 is free to move to the non-baffle position. The fourth surface abuts the third surface, preventing further movement of the valve member 35 toward the open position.

Figures 12 to 14 show the nozzle 40 and the distal portion of the valve needle 35 in more detail.

The nozzle 40 has a nozzle body extending along a longitudinal axis (X) from a base 42 at the proximal end 41 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 intermediate or open position. A straight main bore 50 extends longitudinally from the inlet 48 into the nozzle body. The closed distal end 44 has a substantially planar end face 47 with a circular or elliptical profile. The end face 47 connects to the cylindrical portion via a curved or rounded transition surface 49.

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.

The multiple main nozzle holes 45 each open at a different radial angle into the outer surface of the nozzle body 43, and when the fuel valve 30 is in an open state, create a fan-shaped fuel jet in the combustion chamber, as shown in FIG. 14. The main nozzle holes 45 each open at a different radial angle into the outer surface of the nozzle body 43. 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.

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, along the major axis X, into the cylindrical portion 43, and terminates near the distal end 44 of the nozzle body. The main bore 50 connects to the main nozzle bore 45 a first axial distance from the distal end 44 and to the pilot nozzle bore 46 a second axial distance from the distal end 44. The second axial distance is shorter than the first axial distance. Therefore, flow from the main bore 50 to the pilot nozzle bore 46 is possible with a smaller lift (smaller 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 (larger axial displacement) of the valve member 35 toward the open position. This difference in lift between 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. Figure 13 shows the valve member 35 in the open position, and Figure 14 shows the valve member 35 in the intermediate position.

The valve needle 35 has a distal portion with a cylindrical end 39 carried by 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.

As depicted in Figures 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.

When the valve member 35 is in the intermediate position, lift or axial movement of the valve member to the open position only causes the cylindrical portion 39 to cover the opening to the main nozzle hole 45, thereby injecting fuel 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.

As depicted in Figures 5 and 7, when the valve member 35 is in the open position, the cylindrical end 39 does not block the openings of either the pilot nozzle hole 46 or the main nozzle hole 45 from the straight main hole 50, connecting the openings of both the pilot nozzle hole 46 and the main nozzle hole 45 to 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).

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

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 (27)

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 an intermediate position 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 surface 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 also to fuel 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 electronic control valve 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 the baffle member:
moving to the obstructing 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:
Fuel valve. The fuel valve of claim 1, wherein the first fuel chamber is fluidly connected to the fuel inlet port and the fuel control port. The fuel valve of claim 1, wherein 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. The fuel valve of claim 1, wherein 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. The fuel valve of claim 1, wherein the size of the first surface of the valve member is smaller than the size of the second surface of the baffle member. The fuel valve of claim 1, wherein the baffle member has a plunger fitted 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. 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. The fuel valve of claim 7, wherein the displaceable valve member is seated on a valve seat in the closed position and is unseated from the valve seat in the open position and the intermediate position. 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 provided in a nozzle, the nozzle being located at the distal end. The fuel valve of claim 9, wherein the nozzle comprises a nozzle body having a region along the longitudinal axis extending from a base at the 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. 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;
a single straight main bore extending longitudinally from said inlet into said nozzle body;
The fuel valve of claim 10, comprising: A fuel valve as described in claim 11, wherein the main nozzle hole and the pilot nozzle hole are connected to the main hole at positions axially spaced apart from each other. the displaceable valve member has a distal portion with a cylindrical end carried on a stem, the cylindrical end fitting snugly within the straight main bore as an axis;
fluidly isolating the main nozzle bore and the pilot nozzle bore from the straight main bore when the displaceable valve member is in a closed position;
when the displaceable valve member is in an intermediate position, fluidly disconnecting the main nozzle bore from the straight main bore and fluidly connecting the pilot nozzle bore 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. the cylindrical end is hollow to form a fluid passage;
The fluid passage opens proximally to the exterior of the stem and opens axially distally.
14. The fuel valve of claim 13. A fuel valve as described in claim 1, wherein the cross-sectional area of the pilot nozzle hole is smaller than the cross-sectional area of the main nozzle hole. The fuel valve of claim 1, wherein the main nozzle hole and/or the pilot nozzle hole is a bore. 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 the closed position, and the valve needle unseating from the valve seat in the open and intermediate positions. 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. The fuel valve of claim 18, wherein the valve seat and/or the second fuel chamber are disposed within the elongated valve body. The fuel valve of claim 1, wherein the plurality of main nozzle holes all have the same cross-sectional area or diameter. The fuel valve of claim 1, wherein the plurality of main nozzle holes all have the same length. The fuel valve of claim 1, wherein the plurality of pilot nozzle holes all have the same cross-sectional area or diameter. The fuel valve of claim 1, wherein the plurality of pilot nozzle holes all have equal lengths. A fuel valve as described in claim 20, wherein the cross-sectional area or diameter of the main nozzle hole is larger than the cross-sectional area or diameter of the pilot nozzle hole. The fuel valve according to claim 11 , wherein the main nozzle hole and/or the pilot nozzle hole opens into a surface of the elongated portion . 2. The fuel valve of claim 1, wherein the electronically controlled valve is a spool valve or a solenoid valve . A crosshead-type large two-stroke turbocharged uniflow scavenged internal combustion engine equipped with a fuel valve according to any one of claims 1 to 26.