JP6745394B2 - Large two-stroke compression ignition internal combustion engine with fuel injection system for low flash point fuel and fuel valve therefor - Google Patents

Description

The present disclosure relates to a large-sized low-speed operation two-stroke compression ignition internal combustion crosshead engine including a fuel injection system that injects low flash point fuel into a combustion chamber.

background

Large 2-stroke uniflow turbocharged compression ignition internal combustion crosshead engines are commonly used as propulsion systems for large ships and as primary movers in power plants. The large size, weight, and energy output of a large two-stroke turbocharged compression ignition internal combustion engine make it an engine unlike any other conventional combustion engine.

Large-scale two-stroke compression ignition internal combustion engines have traditionally been driven by liquid fuels such as fuel oil and heavy oil, but due to increased environmental concerns, gas, methanol, coal slurry, petroleum coke, etc. Development is underway for the use of these types of fuels. One of the fuel groups that is in high demand is the low flash point fuel group.

Many low flash point fuels are relatively clean, such as methanol, ethanol, Liquefied Petroleum Gas (LPG), Dimethyl Ether (DME) or biofuels, naphtha, gasoline, crude gasoline, and crude oil. When used as fuel for a large-scale low-speed uniflow turbocharged two-stroke internal combustion engine, it is a sulfur compound, nitrogen oxide (NOx), and carbon dioxide in exhaust gas as compared with the case where heavy oil is used as fuel. The (CO ₂ ) level is significantly reduced.

However, the use of low flash point fuel in large low speed uniflow turbocharged two stroke internal combustion engines is associated with some problems. One of the problems is the low flash point. This creates a significant problem if the low flash point fuel leaks into any other engine system (eg, the lubricating oil system) and mixes with other fluids. Low flashpoint fuels are inherently flammable and their vapors are subject to explosive mixtures. Therefore, when a low flash point fuel intrusion route to another engine system is found, it is necessary to stop the engine operation and wash or replace all the liquids in the system for safety measures. This is a cumbersome and expensive task for engine operators.

As is well known to those skilled in the art, a common rail system that stores low flash point fuel and distributes it at the required injection pressure (usually several hundred bar depending on the type of low flash point fuel and engine requirements) and close to the fuel valve. A large two-stroke compression ignition internal combustion engine with an accumulator is provided. The common rail system is connected to two or three fuel injection valves in the cylinder cover of each cylinder. The fuel injection timing is determined by electronically controlling the fuel injection valve (relative to the engine cycle) and electronically controlling the timing at which the fuel injection valve is opened (the signal occurs in the electronic controller, but in practice The signal provided to the fuel valve is usually a hydraulic signal, i.e. the electronic signal is converted into a hydraulic signal between the electronic control unit and the fuel valve).

Known common rail gas fueling systems for large two-stroke compression ignition internal combustion engines are disadvantageous when operated with relatively compressible LPG or similar low flash point fuel. The injection pressure of LPG needs to be as high as 600 bar. In other words, it is necessary to layout all valves, accumulators, common rail type systems including pipes, etc., for this high pressure. Moreover, the window valve safety concept is not well suited for high density gases such as LPG. The reason is that, firstly, the volume of the gas flow path between the window valve and the fuel valve needs to be made very small, and secondly, due to the high-frequency vibration excited by the closing of the window valve, a reliable Monitoring the gas flow path pressure required for leak detection can be extremely difficult.

It is also known to those skilled in the art to use a booster pump and a fuel pressure controllable fuel valve to inject a liquid gas (eg, LPG). This concept is associated with the problem that the compressibility of LPG is quite large and depends on pressure, temperature and gas composition. Therefore, depending on these parameters, a delay occurs between the operation of the pressure booster and the actual gas injection, which makes it extremely difficult to control the engine, such as the injection amount, especially the injection timing. This is a serious problem in compression ignition engines because injection timing is extremely important.

EP 3252291 uses a pressure booster to enable precise injection timing of a low flash point (and higher compressibility compared to liquid fuel) fuel supply system according to the preamble of claim 1. Is disclosed.

However, most low flash point fuels do not have good ignitability, so if the ignition liquid is not injected into the combustion chamber immediately before the low flash point fuel or at the same time as the low flash point fuel, the reliability of ignition is reduced. ..

Therefore, a fuel supply system for LPG and a low flash point fuel similar to LPG, which is safe, inexpensive, and which realizes accurate control of fuel intake timing into a cylinder and highly reliable ignition, is provided. There is a need to.

As is well known, a plurality of independent valves are used to inject the ignition liquid into the combustion chamber. However, an engine that operates with a low flash point fuel is generally a two-system fuel engine that can also operate with a conventional fuel such as fuel oil or heavy oil, and a cylinder cover has fuel valves for a conventional fuel and a low flash point fuel. Each has two or three. Therefore, there are already four to six fuel valves in the cylinder cover, which are already full without additional valves to inject the ignition liquid. Furthermore, the amount of ignition liquid injected is generally much smaller than the amount of low flash point fuel. Generally, the amount of ignition liquid fuel is in the range of 1.5% to 5% by weight of the low flash point fuel. Accordingly, the valve that injects the ignition liquid is significantly smaller than the fuel valve that injects the low flash point fuel. Such miniature valves are generally extremely fragile and intolerant of harsh environments.

Summary

It is an object of the present invention to provide a large two-stroke turbocharged compression ignition internal combustion crosshead engine that solves or at least alleviates the above problems.

The above and other objects are achieved by the features of the independent claims. Further embodiments are set forth in the dependent claims, the description of the invention and the drawings.

According to the first aspect, there is provided a fuel valve for injecting a low flash point liquid fuel into a combustion chamber of a large-sized low-speed operation two-stroke turbocharged compression ignition internal combustion engine. This fuel valve
An elongated valve housing having a rear end and a tip,
A nozzle having a plurality of nozzle holes disposed at the tip of the elongated valve housing;
A fuel inlet port in the elongated valve housing for connecting to a pressurized low flash point fuel source;
A working fluid port in the elongated valve housing for connecting to a working fluid source;
An axially displaceable valve needle having a closed position and an open position and biased to the closed position, slidably housed in a longitudinal hole of the fuel valve,
A valve needle that allows fuel to flow from the fuel cavity to the plurality of nozzle holes when in the open position and blocks fuel flow from the fuel cavity to the plurality of nozzle holes when in the closed position;
A pump piston housed in a first hole in the valve housing and having a pump chamber in the first hole on one side, the pump piston comprising:
A pump piston slidably accommodated in the first hole with a gap between the pump piston and the first hole;
A working piston housed in a second hole in the valve housing having a working chamber in the second hole on one side, the pump piston being operably connected to the working piston,
The working chamber is fluidly connected to the working fluid port,
An operating piston having an outlet fluidly connected to the fuel cavity and an inlet fluidly connected to the fuel inlet port;
A sealing liquid introduction port for connecting to a pressurized sealing liquid source,
A sealing oil flow path for sealing the valve needle in the vertical hole by connecting the sealing liquid introduction port to the vertical hole,
An ignition liquid introduction port for connecting to a pressurized ignition liquid source,
An ignition liquid conduit extending from the ignition liquid introducing port to the gap for sealing the pump piston in the first hole and supplying an ignition liquid to the pump chamber.

By providing an inlet port for the ignition liquid and providing a conduit for transferring the ignition liquid to the first hole to seal the pump piston in the first hole with overpressure, the ignition liquid seals the pump piston, and The ignition liquid reaches the pump chamber because a gap is opened between the pump chamber and the pump chamber. This causes a small amount of ignition liquid to reach the pump chamber and mix with the low flash point fuel. A small amount of ignition liquid mixed with the low flash point fuel is pumped to the nozzle and injected into the combustion chamber. The ignition reliability is improved by mixing the ignition liquid with the low flash point fuel.

According to a possible first embodiment of the first aspect, the pump piston is sealed in the first hole by the ignition liquid supplied to the gap through the ignition liquid conduit.

According to a possible second embodiment of the first aspect, the gap opens towards the pump chamber and the ignition liquid is supplied to the pump chamber through the gap.

According to a possible third embodiment of the first aspect, the flow path is a conduit in the valve housing connected to the sealing liquid introduction port and/or the valve needle in the direction of the valve seat. A spring chamber for the biasing spring, and/or an axial hole in the valve needle, and/or a lateral hole in the valve needle.

According to the possible fourth embodiment of the first aspect, the sealing oil flow path is formed by connecting the sealing liquid introduction port to the vertical hole at a first position in the longitudinal direction of the vertical hole. Seal the valve needle.

According to a possible fifth embodiment of the first aspect, the low-flame line is at a second position in the longitudinal direction of the vertical hole, the second position being closer to the fuel cavity than the first position. A point fuel introduction port is connected to the vertical hole. Since the pressure in the low pressure line is significantly lower than the injection pressure, connecting to the low pressure line “breaks” the high pressure condition resulting from the fuel cavity. Therefore, the sealing oil only needs to seal the gap between the valve needle and the vertical hole against the low fuel pressure in the low pressure line.

According to a possible sixth embodiment of the first aspect, the valve needle rests on the valve seat in the closed position and rises above the valve seat in the open position.

According to a possible seventh embodiment of the first aspect, the nozzle has a nozzle body fixed to the front of the elongated valve housing.

According to a possible eighth embodiment of the first aspect, the valve seat is located at the tip of the nozzle.

According to a possible ninth embodiment of the first aspect, the vertical hole is formed in at least a part of the nozzle body.

According to a possible tenth embodiment of the first aspect, the raising of the valve needle is controlled by the fuel pressure in the fuel cavity.

According to a possible eleventh embodiment of the first aspect, the valve needle is controllable with the pressure surface of the needle working piston facing the needle working chamber in the fuel valve and the needle working chamber being controllable. Operatively connected to the needle actuated piston in fluid connection with a control port of the fuel valve for connection to a source of control fluid.

According to a possible twelfth embodiment of the first aspect, the fuel valve is a valve needle controlling the flow of fuel into the nozzle hole of the nozzle of the fuel valve, the position of the valve needle preferably being A valve needle is provided which is controlled by a control signal rather than the fuel pressure.

According to a possible thirteenth embodiment of the first aspect, the pump chamber has an inlet fluidly connected to the fuel inlet port via a first one-way valve.

According to a possible fourteenth embodiment of the first aspect, the pump chamber has an outlet fluidly connected to the fuel cavity via a second one-way valve.

According to a fifteenth possible embodiment of the first aspect, the effective pressure range of the pump piston is smaller than the effective pressure range of the working piston.

According to a possible sixteenth embodiment of the first aspect, the nozzle is part of a nozzle body fixed to the front of the elongated valve housing.

According to a possible seventeenth embodiment of the first aspect, the inlet is located in the pump piston.

According to a possible eighteenth embodiment of the first aspect, it is arranged to allow a low flash point fuel flow into the pump chamber through the inlet and impede flow from the pump chamber to the inlet. The first one-way valve is installed at the inlet.

According to a possible nineteenth embodiment of the first aspect, the outlet of the pump chamber is connected to the fuel cavity by one or more fuel channels.

According to a possible twentieth embodiment of the first aspect, it is configured to allow the flow of low flash point fuel from the pump chamber to the fuel cavity and to prevent the flow from the fuel cavity to the pump chamber. A second one-way valve is provided in the one or more fuel channels.

According to a possible twenty-first embodiment of the first aspect, the pump piston is operatively connected to and moves integrally with the working piston.

According to a second aspect, a large two-stroke turbocharged compression ignition internal combustion crosshead engine,
Multiple cylinders,
Two or more fuel valves according to a possible embodiment of the first aspect or any of the first aspects arranged in each cylinder, the source of pressurized ignition liquid Pi and the source of pressurized sealing oil Ps. And a fuel valve connected to the low flash point fuel supply system.

According to a possible first embodiment of the second aspect, the pressure of the pressurized ignition liquid source is electronically controllable, and the engine is electronically configured to control the pressure of the pressurized ignition liquid source. Have a device.

According to a possible second embodiment of the second aspect, the engine comprises a non-low flash point fuel supply system and the cylinder comprises two or more fuel valves for injecting the non-low flash point fuel into the cylinder. Equipped with.

The above and other aspects of the present invention will be made clear by the embodiments described below.

In the following detailed description of the present disclosure, the present invention will be described in more detail with reference to the exemplary embodiments illustrated in the drawings.
FIG. 1 is an elevation front view of a large two-stroke diesel engine according to an example embodiment. 2 is a side elevational view of the large two-stroke engine of FIG. FIG. 3 is a diagrammatic representation of the large two-stroke engine of FIG. FIG. 4a is a schematic representation of a fuel injection system for injecting low flash point fuel into the engine of FIGS. FIG. 4b is a schematic representation of one embodiment of a fuel valve used in the engine of FIGS. 1 and 2, showing each liquid source connected to the fuel valve. FIG. 5 is an elevation view of the fuel valve according to the embodiment. FIG. 6 is a cross-sectional view of the fuel valve of FIG. FIG. 7 is a sectional view of the fuel valve of FIG. FIG. 8 is a sectional view of the fuel valve of FIG. FIG. 9 is a sectional view of the fuel valve of FIG. FIG. 10 is a diagram showing another nozzle in the fuel valve of FIG.

In the following detailed description, the internal combustion engine will be described with reference to a large two-stroke low speed uniflow turbocharged compression ignition internal combustion engine with a crosshead in the example embodiment, which internal combustion engine will be turbocharged or exhaust gas. It goes without saying that other types of engines, such as 2-stroke Otto with or without recirculation, 4-stroke Otto, or diesel may be used.

1, 2 and 3 show a large low speed turbocharged two stroke diesel engine equipped with a crankshaft 8 and a crosshead 9. FIG. 3 schematically shows a large-sized low-speed turbocharged two-stroke diesel engine having an intake system and an exhaust system. In this embodiment, the engine has six cylinders arranged in a line. Generally, a large-sized low-speed turbocharged two-stroke diesel engine has 4 to 14 cylinders supported by a cylinder frame 23 in one row, and the cylinder frame 23 is supported by the engine frame 11. This engine is used, for example, as a main engine of a ship or a stationary engine for driving a generator of a power plant. The total output of this engine is, for example, in the range of 1,000 kW to 110,000 kW.

The engine of the present embodiment is a two-stroke uniflow type compression ignition engine in which a scavenging port 18 is provided below the cylinder liner 1 and a central exhaust valve 4 is provided at the top of the cylinder liner 1. The scavenging air is sent from the scavenging air receiver 2 to the scavenging port 18 of each cylinder 1. The scavenging air is compressed by the piston 10 in the cylinder liner 1. Fuel is injected through the fuel valve 50 in the cylinder cover 22. When fuel is injected, combustion occurs and exhaust gas is generated. The fuel valve 50 is adapted to inject low flash point fuel into the combustion chamber. The engine in one embodiment further comprises a fuel valve 51 adapted to inject conventional fuel (eg, non-low flash point fuel such as fuel oil or heavy oil) into the combustion chamber.

When the exhaust valve 4 opens, the exhaust gas flows into the exhaust gas receiver 3 through the exhaust duct attached to the cylinder 1, passes through the first exhaust pipe line 19 and proceeds to the turbine 6 of the turbocharger 5, and the turbine 6 through the second exhaust pipe, the economizer 20, and the exhaust port 21 into the atmosphere. The turbine 6 drives a compressor 7 via a shaft (outside air is supplied to the compressor 7 from an air suction port 12). The compressor 7 supplies the compressed scavenging air to the scavenging air pipe line 13 leading to the scavenging air receiver 2. The scavenging air in the scavenging air pipe line 13 passes through an intercooler 14 for cooling the scavenging air.

The cooled scavenging air passes through an auxiliary blower 16 driven by an electric motor 17. The auxiliary blower 16 pressurizes the scavenging air flow when the compressor 7 of the turbocharger 5 does not supply sufficient pressure to the scavenging air receiver 2, that is, when the engine is in a low load or partial load state. When the engine load is high, the compressor 7 of the turbocharger supplies sufficient compressed scavenging air, and the auxiliary blower 16 is bypassed via the check valve 15.

This engine is a low flash point fuel such as LPG, methanol, naphtha, etc., which is supplied by a low flash point fuel supply system 30 in a liquid or supercritical state under substantially stable pressure and temperature. Operates on point fuel. However, it is inevitable that the temperature and pressure slightly fluctuate depending on the detailed configuration of the low flash point fuel supply system and the type of supply gas. In addition, there may be some variation in the composition of the low flash point fuel. The engine in one embodiment is a dual fuel engine and also includes a conventional fuel supply system (not shown) that supplies non-low flash point fuels such as fuel oil and heavy oil.

The low flash point fuel supply system 30 supplies the low flash point fuel to the fuel injection valve 50 via the supply line 31 at a relatively low supply pressure (for example, 8 to 100 bar pressure).

FIG. 4 a is a diagram showing a fuel injection system that receives low flash point fuel via the supply line 31. The fuel injection system includes a pressure booster 40 that pressurizes the fuel to the injection pressure. The pressure booster 40 operates hydraulically under the control of the first control valve 41. The fuel valve 50 operates hydraulically under the control of the second control valve 45.

FIG. 4 a is a diagram showing a fuel injection system in one cylinder 1 including one pressure booster 40 and three fuel injection valves 50. Each cylinder 1 may be provided with two fuel valves 50 instead of three. Each cylinder 1 requires a pressure booster 40 to fuel two or three fuel valves 50.

The pressure booster 40 comprises a large diameter plunger that is connected to and moves with the small diameter plunger. The large diameter plunger and the small diameter plunger are respectively accommodated in corresponding holes in the housing of the pressure booster 40. The large-diameter plunger faces a working chamber that is supplied with high-pressure hydraulic oil or is connected to a tank under the control of the first control valve 41.

The small-diameter plunger faces a pump chamber connected to the supply line 31 via a one-way valve and connected to a high-pressure fuel supply line 35 for supplying high-pressure fuel to the fuel valve 50. The one-way valve prevents the reverse flow of fuel from the high pressure fuel supply line 35 to the pump chamber. The pressure of the fuel in the supply line 31 is sufficient to cause the pressure booster 40 to perform a return stroke when the working chamber is connected to the tank. The position sensor 34 is a sensor that detects the positions of the large diameter plunger and the small diameter plunger.

The first control valve 41 in the present embodiment preferably comprises a first proportional hydraulic control type three-way valve 42. The first three-way valve 42 is connected to the working chamber via the working pipe line 44, and is also connected to the high pressure hydraulic oil source and the tank. The first three-way valve 42 is configured to selectively connect the working chamber to a tank or a high pressure hydraulic oil source. Since the first hydraulically controlled three-way valve 42 in one embodiment is a proportional valve, it can assume any intermediate position between its connection to the high pressure hydraulic oil source and its connection to the tank. The position of the first three-way valve 42 is controlled by the first small two-way valve 43, and the position of the first small two-way valve 43 is electronically controlled. The first small two-way valve 43 is connected to the electronic control unit 25 via the first signal cable 26. In one embodiment, the first control valve 41 is operated by the instruction of a separate electronic control unit. This electronic control unit is mainly designed for safety, and stops the operation of the pressure booster when a safety problem such as gas leakage is detected. Alternatively, the first control valve is connected to a high pressure hydraulic oil source controlled by the engine maintenance system.

The high pressure fuel supply line 35 is branched into three high pressure fuel supply lines 35-1, 35-2 and 35-3. That is, one high-pressure fuel supply line supplies high-pressure low flash point fuel to each fuel valve 50. In the embodiment having two fuel valves 50 in one cylinder, the high pressure fuel supply line 35 is branched into two lines.

As shown in FIG. 4b, each fuel valve 50 is connected to the supply source of the pressurized sealing oil Ps by the sealing oil supply line 36 and the sealing oil return line. In one embodiment, the flow of sealing oil through the fuel valve 50 is relatively high so that the sealing oil also functions as a refrigerant for the fuel valve 50.

Each fuel valve 50 is connected to a fuel valve actuation signal line 48. The pressure in the fuel valve actuation signal line 48 is controlled by the second control valve 45. In one embodiment, the second control valve 45 comprises a second hydraulically controlled proportional three-way valve 46 and a second small electronically controlled two-way valve 47. The second hydraulically controlled proportional three-way valve 46 is preferably a proportional valve and is configured to connect the actuation signal line 48 to a high pressure hydraulic oil source or tank. Since the second hydraulically controlled three-way valve 46 in one embodiment is a proportional valve, it can assume any intermediate position between its connection to the high pressure hydraulic oil source and its connection to the tank. The position of the second three-way valve 46 is controlled by the second small two-way valve 47, and the position of the second small two-way valve 47 is electronically controlled. The second small two-way valve 47 is connected to the electronic control unit 25 via the third signal cable 28. The electronic control unit 25 is notified of the position of the second three-way valve 46 via the second signal cable 27.

The electronic control unit 25 receives signals from various sensors via signal cables (shown in broken lines in Figure 4a). Signals from various sensors include, for example, scavenging pressure, temperature, exhaust pressure, temperature, crank angle, and speed signals. However, it should be noted that the types of signals are not covered by these, for example whether the engine is equipped with an exhaust gas recirculation mechanism or whether the engine is equipped with a turbocharger, It may change depending on the structure of the engine. The electronic control unit 25 controls the fuel injection valve 50. That is, the electronic control unit 25 determines the valve opening timing and the valve opening period of the fuel valve 50. The electronic control unit 25 also controls the operation of the pressure booster 40.

The timing of fuel injection greatly affects the combustion pressure of a large two-stroke turbocharged internal combustion engine (compression ignition engine). The opening timing of the fuel valve 50 with respect to the crankshaft angle or the engine cycle mainly determines the combustion pressure. The amount of fuel accommodated in the cylinder 1 is determined by the valve opening period of the fuel valve 50, and the amount of fuel accommodated in the cylinder 1 increases as the valve opening period increases.

The electronic control unit 25 is configured to control the valve opening timing of the fuel valve by sending an electronic signal to the second control valve 45 via the third signal cable 28. Upon receipt of the signal, the electronic control valve switches positions to connect the actuation signal line 48 to a high pressure hydraulic oil source. The high pressure in actuation signal line 48 causes fuel valve 50 to open.

In the above embodiment, the pressure booster 40 and the fuel valve 50 are separate physical devices. In one embodiment, pressure booster 40 and fuel valve 50 are an integral part.

One embodiment of a fuel valve 50 integrated with a pressure booster is shown in FIGS.

FIG. 5 is a perspective view of the fuel valve 50 including the elongated valve housing 52 and the nozzle 54 fixed to the tip of the elongated valve housing 52. The nozzle 54 has a plurality of nozzle holes 56 that generate a fuel jet into the combustion chamber. The nozzle 54 is removably secured to the elongated valve housing 52 for easy replacement if the nozzle 54 fails or wears.

6, FIG. 7, FIG. 8 and FIG. 9 show different cross sections of the fuel valve 50. The fuel valve 50 has an elongated valve housing 52 at the rear end and a nozzle 54 at the front end. The nozzle 54 is separately attached to the tip of the valve housing 52. The rear end of the valve housing 52 is provided with a plurality of ports such as a control port 86, a working fluid port 78, and a gas leak detection port (not shown). The rearmost end of the valve housing 52 is enlarged to form a head that projects from the cylinder cover when the fuel valve 50 is mounted on the cylinder cover. In this embodiment, the fuel valve 50 is installed around the central exhaust valve 4, that is, relatively close to the wall of the cylinder liner. The elongated valve housing 52 and other components of the fuel injector 50 in one embodiment, like the nozzle, are made of steel, such as tool steel or stainless steel.

The nozzle 54 has a plurality of nozzle holes that communicate with the inside of the nozzle 54. These nozzle holes are arranged in different directions to disperse the fuel in the combustion chamber. The orientation of the nozzle holes is away from the relatively close cylinder liner, which is based on the position of the fuel valve 50 in the cylinder head. The nozzle holes are arranged at the tip 56 of the nozzle 54. Further, the nozzle holes are oriented so as to be substantially in the same direction as the direction of the scavenging scavenging gas in the combustion chamber generated by the shape of the scavenging port (this vortex is a large uniflow type two-stroke turbocharged internal combustion engine). Is a well-known feature in).

The nozzle 54 is connected to the tip of the valve housing 52 with a union nut 57. The union nut 57 secures and surrounds a portion of the nozzle body 55, surrounds the intermediate portion 53 and also surrounds the distal end of the elongated valve housing 52. The nozzle body 55 has a vertical hole in which the valve needle 61 is accommodated. The diameter of this vertical hole is larger than the diameter of the valve needle 61 at the portion of the vertical hole closest to the tip 56. The space between the vertical hole and the valve needle 61 forms the fuel cavity 58. There is a small gap between the middle portion of the vertical hole and the valve needle 61. The portion of the vertical hole of the nozzle body 55 farthest from the tip 56 of the nozzle 54 is expanded in diameter in accordance with the expanded diameter portion of the valve needle 61. The enlarged portion of the valve needle 61 forms a needle actuating piston 62. The needle actuating piston 62 has a pressure surface facing the needle actuating chamber 88 within the nozzle 54. Needle working chamber 88 is fluidly connected to control port 86 through control line 87. The control port 86 is connected to the control oil Pc source.

The expanded diameter portion of the vertical hole is aligned with the spring chamber 96 in the intermediate portion 53. The spring chamber 96 is aligned with the vertical hole of the elongated valve housing 52. The end of the longitudinal hole of the elongated valve housing 52 closest to the end of the valve needle 61 has a diameter that matches the diameter of the spring chamber 96. A helical wire spring 68 extends between the end of the longitudinal hole in the elongated valve housing 52 and the enlarged portion 62 of the valve needle 61. The valve needle 61 is resiliently biased by a pre-tensioned helical wire spring 68 toward the closed position of the needle. The spiral wire spring 68 is housed in a spring chamber 96 in the elongated fuel valve housing 52. The helical wire spring 68 biases the valve needle 61 towards the tip 56 of the nozzle 54, i.e. towards the closed position of the needle. In the closed position of the valve needle 61, the preferably conical tip of the needle abuts against the preferably conical valve seat 63 in the tip 56 inside the nozzle 54 to provide fluid communication between the fuel cavity 58 and the nozzle hole. Close the connection. The fluid connection between the fuel cavity 58 and the nozzle hole was propelled when the valve needle 61 was raised, that is, the valve needle 61 resisted the biasing force of the helical wire spring 68 toward the proximal end of the fuel valve 50. When established. When the needle working chamber 88 is pressurized, the valve needle 61 is raised.

A spring guide 69 extends concentrically within the spring chamber 96 and guides the spiral wire spring 68. The proximal end of the spring guide 69 is sealingly received in a vertical hole in the elongated valve housing 52.

The axially displaceable valve needle 61 is slidably accommodated in the vertical hole of the nozzle body 55 with a minute gap. Here, lubrication of the axially displaceable valve needle 61 and the vertical hole is extremely important. In this regard, the pressurized sealing liquid is supplied to the minute gap between the vertical hole and the valve needle via the conduit 93. The channel 93 connects the minute gap between the valve needle 61 and the vertical hole to the sealing liquid introduction port 70. The sealing liquid inlet 70 can be further connected to a pressurized sealing liquid source. The connection between the minute gap and the channel 93 includes a lateral hole 99 (FIG. 8) in the valve needle 61, which communicates with an axial hole 97 (FIG. 8) in the valve needle 61. The hole 97 extends to the spring chamber 96 over the entire length of the enlarged portion forming the needle actuating piston 62. The channel 93 leads to the spring chamber 96 and supplies the spring chamber 96 with a pressurized sealing liquid. The spring chamber 96 is connected to the sealing liquid discharge port 95 through a hole so that a large amount of the sealing liquid flows into the spring chamber 96 and the sealing liquid functions as a refrigerant. The sealing liquid prevents the low flash point fuel from leaking through a minute gap between the valve needle 61 and the axial hole and cools the fuel valve 50. Furthermore, the sealing liquid (preferably oil) lubricates between the valve needle 61 and the vertical hole.

The elongated valve housing 52 includes a fuel inlet port 76 for connecting to a source of pressurized low flash point liquid fuel through, for example, the low flash point liquid fuel supply line 31. The fuel introduction port 76 communicates with a pump chamber 82 in the valve housing 52 via a conduit 73 in the pump piston 80 and a one-way valve 89 (preferably a spring-loaded poppet valve). A one-way valve 89 (intake valve) is provided in the pump piston 80 at the position of the inlet 71 of the conduit 73. The one-way valve 89 is a spring-loaded poppet valve that allows the liquid low flash point fuel to flow from the fuel introduction port 76 through the conduit 73 to the pump chamber 82 and not in the opposite direction. A fluid connection between the line 73 in the pump piston 80 and the fuel inlet port 76 in the elongated valve housing 52 is formed by the retract region 74 in the pump piston 80. The receding region 74 axially overlaps a hole in the elongated valve housing 52 that forms the fuel inlet port 76.

The pump piston 80 is slidably and sealingly housed on one side in a first bore 81 in an elongated fuel valve housing 52 with a pump chamber 82. The working piston 83 is slidably and sealingly housed on one side in a second hole 84 in the valve housing 52 with a working chamber 85. The pump piston 80 is connected to and moves integrally with the working piston 83. That is, the pump piston 80 and the working piston 83 can be slid together in the corresponding holes 81 and 84. In this embodiment, the pump piston 80 and the working piston 83 are integrally manufactured. However, it should be noted that the pump piston 80 and the working piston 83 may be separate and interconnected.

Working chamber 85 is fluidly connected to working fluid port 78. The first control valve 41 controls the flow of the pressurized hydraulic fluid that enters and leaves the working fluid port 78, thereby controlling the flow of the pressurized hydraulic fluid that enters and exits the working chamber 85.

During the lead time before the start of the injection stroke, the electronic control unit 25 instructs the first control valve 41 to cause the high pressure hydraulic fluid to flow into the working chamber 85. At this time, the connected operating piston 83 and pump piston 80 are at the positions shown in FIG. The pressurized hydraulic fluid in the working chamber 85 acts on the working piston 83 to generate a force for propelling the pump piston 80 into the pump chamber 82. This increases the pressure of the low flash point liquid fuel in the pump chamber 82. In one embodiment, the working piston 83 has a larger diameter than the pump piston 80 and correspondingly the pressure in the pump chamber 82 is higher than the pressure in the working chamber 85. Further, the working piston 83 and the pump piston 80 connected to each other function as a pressure booster.

One or more fuel channels 79 fluidly connect pump chamber 82 to fuel cavity 58, which in turn fluidly connects a valve seat located at the bottom of fuel cavity 58. A one-way valve 90 is installed between the fuel channel 79 and the pump chamber 82. The outlet 66 of the pump chamber 82 is connected to the inlet of the one-way valve 90. The one-way valve 90 includes a valve member slidably received in an axial hole of the elongated valve housing 52, the valve member being resiliently biased toward a valve seat, i.e., a valve closing direction, Backflow of fuel from the fuel channel 79 into the pump chamber 82 is prevented.

As shown in FIG. 7, the pressurized fluid in the working chamber 85 moves the working piston 83 and the pump piston 80 downward (downward in FIGS. 6 to 9). The pressure in the pump chamber 82 after a short compression period is equal to the product of the ratio of the effective pressure range of the pump piston 80 and the working piston 83 to the pressure in the working chamber 85. At this time, the pressure in the working chamber 85 becomes substantially equal to the pressure of the high pressure fluid source. With an effective pressure surface ratio of, for example, 2.5:1 and a hydraulic system supply pressure of, for example, 225 to 300 bar, the fuel pressure in the pump chamber at the end of the compression period is about 500 bar. In this way, the working piston 83 and the pump piston 80 connected together function as a pressure booster.

The electronic control unit 25 pressurizes the working chamber 85 for a sufficient lead time to ensure that the pressure in the pump chamber 82 reaches the required injection pressure (for example 500 bar) before starting the fuel injection. The electronic control unit 25 determines when the valve needle 61 needs to be lifted, that is, the start timing of fuel injection. The valve needle 61 is configured to obtain a lift force by moving in the direction away from the nozzle 54 and reduce the lift force by moving in the direction of the nozzle 54. The valve needle 61 obtains lift when the needle working chamber 88 is pressurized. When it is necessary to start fuel injection in the engine cycle, the electronic control unit 25 instructs the second control valve 45 to connect the fuel valve actuation signal line 48 to the high pressure hydraulic oil source. The fuel valve actuation signal line 48 is connected to the control port 86 and high pressure fuel reaches the needle actuation chamber 88 through the control line 87. As the valve needle 61 rises from the valve seat, the low flash point liquid fuel can flow from the fuel cavity 58 through the nozzle holes and into the combustion chamber.

The electronic control unit 25 instructs the second control valve 45 to connect the needle working chamber 88 to the tank, thereby ending the injection stroke. Then, the valve needle 61 returns to the valve seat to prevent further fuel injection. At the same time or shortly thereafter, the electronic control unit 25 instructs the first control valve 41 to connect the working chamber 85 to the tank. The pump chamber 82 is connected to the pressurized low flash point fuel source 30, and the working pressure of the low flash point liquid fuel flowing in through the one-way valve 89 causes the working piston 83 to be pushed into the working chamber 85 and is shown in FIG. Reach the indicated position. In this state, the pump chamber 82 is completely filled with the low flash point liquid fuel, and the fuel valve 50 is ready for the next injection stroke. FIG. 8 shows the position of the pump piston 80 and the working piston 83 near the end of the injection stroke, with the low flash point fuel being depleted in much of the pump chamber 82.

The electronic control unit 25 controls the injection stroke of the low flash point fuel by the rising timing and the rising period of the valve needle 61. Further, the electronic control unit can also control the injection stroke by adjusting the pressure supplied to the working chamber 85 to perform rate shaping.

The fuel valve 50 includes a sealing liquid introduction port 70 for connecting to the source of the pressurized sealing liquid Ps. In one embodiment, the pressure of the sealing liquid source is equal to or higher than the maximum pressure in the pump chamber 82 during the injection stroke. In another embodiment, the pressure of the sealing liquid source is equal to or higher than the supply pressure of the low flash point fuel.

The sealing liquid is supplied to the minute gap between the vertical hole and the valve needle 61 through the horizontal hole 99, and only the supply pressure of the fuel needs to be sealed. This is because the fuel introduction port 76 is connected to the low pressure fuel pipe line 98, and the low pressure fuel pipe line 98 passes through the elongated valve housing 52 and the intermediate portion 53 in this order from the fuel introduction port 76 and inside the nozzle body 55. This is because the valve needle 61 extends to the vertical hole that is slidably accommodated. The position where the low-pressure fuel line 98 communicates with the vertical hole is an axially intermediate position between the position where the fuel channel 79 communicates with the vertical hole and the position where the lateral hole 99 communicates with the vertical hole. Therefore, all the low flash point fuel leaking upward (upward in FIGS. 6 to 9) from the high-pressure fuel cavity 58 through the minute gap between the vertical hole and the valve needle 61 during the injection stroke is low-pressure fuel pipe. When the passage 98 reaches the position leading to the well, its pressure is reduced to a much lower fuel supply pressure. As described above, the pressure of the fuel in the minute gap between the valve needle 61 and the vertical hole is “broken” by the low pressure in the low pressure fuel pipe 98, so that the sealing liquid from the lateral hole 99 seals against the injection pressure. Stopping is unnecessary and only the sealing against the low flash point fuel supply pressure may be performed. Therefore, the pressure of the sealing oil need only be slightly higher than the supply pressure of the low flash point fuel, and does not have to be higher than the injection pressure of the fuel.

Each fuel valve 50 is connected to a source of pressurized ignition liquid Pi (also called pilot oil). The ignition liquid is a liquid having properties suitable for starting ignition of the main fuel. Fuel oil, for example marine diesel, is an example of a suitable ignition liquid. However, other liquids with good ignitability, such as biodiesel, lubricating oil, heavy oil, dimethyl ether (DME) can also be used.

The valve housing 52 includes an ignition liquid introduction port 92 for connecting to a source of the pressurized ignition liquid Pi. The valve housing 52 is provided with an ignition liquid hole 94 extending from the ignition liquid introduction port 92 to a gap 91 between the pump piston 80 and the first hole 81, whereby the pump piston 80 in the first hole 81 is sealed. It is prevented that the high pressure fuel in the pump chamber 82 is stopped and leaks into the space below the working piston 83. The pump piston 80 is slidably housed in the first hole 81 with a suitably calibrated gap 91 between the pump piston 80 and the first hole 81, the gap 91 facing the pump chamber 82. Open. As a result, a small amount of ignition liquid reaches the pump chamber 82 through the gap 91 between the pump piston 80 and the first hole 81 at each injection stroke. The amount of the ignition liquid that reaches the pump chamber at each injection stroke varies depending on the pressure of the ignition liquid Pi source and the size of the gap 91. The ignition liquid that has reached the pump chamber mixes with the fuel, is supplied to the nozzle 54, and is injected into the combustion chamber together with the fuel. The mixing of a small amount of ignition liquid with the main fuel increases the reliability of ignition of the main fuel in the combustion chamber.

The amount of ignition liquid required for reliable ignition of the main fuel in the combustion chamber (amount for each injection stroke) varies depending on various situations, such as the type of main fuel, the type of ignition liquid, and details of the combustion chamber. It depends on the structure, the detailed structure of the nozzle 54, the fuel injection timing, the compression pressure, the temperature of the scavenging air, and the ratio of the exhaust gas recirculated. However, these do not cover the situations that affect the ignition of the main fuel. Those skilled in the art can determine the above-mentioned required amount by performing simple trial and error.

In one embodiment, the amount of ignition liquid supplied to the pump chamber 82 is adjusted by adjusting the pressure of the ignition liquid source. That is, the pressure of the ignition liquid Pi source is increased when the amount of the ignition liquid needs to be increased, and the pressure is decreased when the amount of the ignition liquid Pi needs to be decreased.

The pressure of the ignition liquid Pi source is always higher than the pressure for supplying the main fuel to the fuel introduction port 76. The pressure at which the ignition liquid Pi is supplied can be higher than the maximum pressure in the pump chamber 82, but this is not usually required. This is because a certain amount of main fuel is allowed to enter the gap 91 between the pump piston 80 and the first hole 81 during the pump stroke.

FIG. 10 shows another type of nozzle 54 used in the fuel valve 50 described above with reference to FIGS. In this embodiment, the nozzle 54 is a so-called slider type, and the valve seat 63 is arranged at a distance from the tip 56 of the nozzle 54. Further, in this embodiment, the nozzle tip 56 is closed. That is, the tip 56 has no nozzle hole. The nozzle holes are arranged not above the tip, but above the tip length (upward in the direction of FIG. 10) along the nozzle length from a position close to the tip 56. The valve needle 61 has a conical portion that cooperates with the valve seat 63, and a slider portion that extends from the conical portion of the valve needle 61 toward the tip of the valve needle 61. A nozzle of this kind with a closed tip and a slider of the valve needle 61 extending towards the tip 56 inside the nozzle 54 is well known in the art and will not be described in further detail.

In one embodiment (not shown), the pressure of the pressurized ignition liquid Pi source is electronically controllable, and the electronic controller 25 is configured to control the pressure of the pressurized ignition liquid Pi source. Therefore, the amount of the ignition liquid supplied to the pump chamber 82 through the gap 91 can be controlled by adjusting the pressure of the pressurized ignition liquid Pi source by the electronic control unit.

In one embodiment, the engine includes a non-low flash point fuel system (not shown) and the cylinder includes two or more fuel valves 51 that inject this non-low flash point fuel into the cylinder.

The inventive concept is not limited to high compression fuels or low flash point fuels.

Although the present invention has been described in connection with various embodiments, upon studying the drawings, the disclosure, and the appended claims, one of ordinary skill in the art will appreciate that the present invention when practicing the claimed invention. Various other variations of the embodiments can be understood and implemented. In the claims, the word "comprising, including, including" does not exclude other elements or steps. Also, singular expressions do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs used in the claims shall not be construed as limiting the scope.

Claims (14)

A fuel valve (50) for injecting a low flash point liquid fuel into a combustion chamber of a large-sized low-speed operation two-stroke turbocharged compression ignition internal combustion engine,
An elongated valve housing (52) having a rear end and a front end;
A nozzle (54) having a plurality of nozzle holes disposed at the tip of the elongated valve housing (52);
A fuel inlet port (76) in said elongated valve housing (52) for connecting to a pressurized low flash point fuel source;
A working fluid port (78) in said elongated valve housing (52) for connecting to a source of working fluid;
An axially displaceable valve needle (61) having a closed position and an open position and biased to the closed position and slidably received in a longitudinal hole of the fuel valve (50). , Allowing fuel flow from the fuel cavity (58) to the plurality of nozzle holes when in the open position and impeding fuel flow from the fuel cavity (58) to the plurality of nozzle holes when in the closed position. A valve needle (61),
A pump piston (80) housed in a first hole (81) in the valve housing (52) and having a pump chamber (82) in the first hole (81) on one side. A pump piston (80) slidably accommodated in the first hole (81) with a gap (91) between the (80) and the first hole (81);
A working piston (83) housed in a second hole (84) in the valve housing (52), the working piston (83) having a working chamber (85) in the second hole (84) on one side. 83) ,
Equipped with
The pump piston (80) is operably connected to the working piston (83),
Said working chamber (85) is fluidly connected to said working fluid port (78),
The pump chamber (82) has an outlet (66) fluidly connected to the fuel cavity (58) and an inlet (71) fluidly connected to the fuel inlet port (76),
The fuel valve (50) further comprises
A sealing liquid introduction port (70) for connecting to a pressurized sealing liquid source,
A sealing oil flow path (93, 96, 97, 99) for connecting the sealing liquid introduction port (70) to the vertical hole and sealing the valve needle (61) in the vertical hole;
An ignition liquid introduction port (92) for connecting to a pressurized ignition liquid (Pi) source,
It extends from the ignition liquid introducing port (92) to the gap (91) for sealing the pump piston (80) in the first hole (81) and supplying ignition liquid to the pump chamber (82). An ignition liquid line (94),
A fuel valve (50). The fuel valve (50) according to claim 1, wherein the pump piston (80) is sealed in the first hole by the ignition liquid supplied to the gap (91) through the ignition liquid conduit (94). ). The fuel valve (50) according to claim 2, wherein the gap opens toward the pump chamber (82), and the ignition liquid is supplied to the pump chamber (82) through the gap (91). The flow path biases a conduit in the valve housing (52) connected to the sealing liquid introduction port (70) and/or the valve needle (61) toward a valve seat (63) . A spring chamber of a spring (96) and/or an axial hole (97) in the valve needle (61) and/or a lateral hole (99) in the valve needle (61). 3. The fuel valve (50) according to any one of 3 above. The sealing oil flow path (93, 96, 97, 99) connects the sealing liquid introduction port (70) to the vertical hole at a first position in the lengthwise direction of the vertical hole to connect the vertical hole with a valve needle. A fuel valve (50) according to any of claims 1 to 4, which seals (61). The pipe line (98) has the low flash point fuel introduction port (76) at the second position in the longitudinal direction of the vertical hole and closer to the fuel cavity (58) than the first position. The fuel valve (50) according to claim 5, wherein the fuel valve (50) is connected to a vertical hole. 7. The fuel valve according to claim 1, wherein the valve needle (61) rests on the valve seat (63) in the closed position and rises from the valve seat (63) in the open position. (50). A fuel valve (50) according to any of the preceding claims, wherein the nozzle (54) has a nozzle body (55) fixed to the front of the elongated valve housing (52). A fuel valve (50) according to any of the preceding claims, wherein a valve seat (63) is located at the tip (56) of the nozzle (54). The fuel valve (50) of claim 8 , wherein the vertical hole is formed in at least a portion of the nozzle body (55). The valve needle (61) is controllable with the pressure surface of the needle working piston (62) facing the needle working chamber (88) in the fuel valve (50), and the needle working chamber (88) is controllable. A needle control piston (62) in fluid connection with a control port (86) of the fuel valve (50) for connection to a source of control fluid (Pc). The fuel valve (50) according to any one of 1 to 10. A large two-stroke turbocharged compression ignition internal combustion crosshead engine,
A plurality of cylinders (1),
Located in each cylinder (1), and two or more fuel valve according to any of claims 1 to 11, (50), pressure point fire solution (Pi) source and, pressurized sealing fluid ( Ps) source and a fuel valve (50) connected to the low flash point fuel supply system,
An engine characterized by comprising. The pressure of the pressure points fire solution (Pi) source is available electronically controlled, the engine has an electronic control unit configured to control the pressure of the pressurizing points fire solution (Pi) source, according to claim 12 Engine described in. The engine comprises a non-low flash point fuel supply system and the cylinder (1) comprises two or more fuel valves (51) for injecting the non-low flash point fuel into the cylinder (1). The engine according to claim 12 or 13 .

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