Fuel valves for large turbocharged two-stroke single-flow crosshead internal combustion engines

Abstract

A fuel valve for injecting liquid fuel into the combustion chamber of a large turbocharged two-stroke single-flow crosshead internal combustion engine comprises a fuel conduit having an inlet end and an outlet end communicating with a fuel injection passage, a fuel inlet passage connecting the inlet end to a plunger chamber, and a fuel outlet passage connecting the plunger chamber to the outlet end. The valve also comprises: a spindle valve member movable in the fuel conduit between at least a first position and a second position, wherein in the first position the valve member allows fuel to flow through the inlet passage to the plunger chamber to fill the plunger chamber with fuel, and in the second position the valve member allows fuel to flow from the plunger chamber to the fuel injection passage to supply fuel to the nozzle; and a component for providing a certain leakage from the outlet passage to the fuel injection passage when the spindle valve member is in the first position. This provides a self-checking safety feature that ensures that overfueling and, consequently, cylinder head lift will not occur if the valve needle becomes stuck in the open position.

Description

Technical Field

[0001] The present invention relates to a fuel valve for injecting liquid fuel into a combustion chamber of a large turbocharged two-stroke single-flow crosshead internal combustion engine, the fuel valve comprising: an elongated fuel valve housing having a rear end and a front end; a nozzle having a plurality of nozzle holes, the nozzles being arranged at the front end of the housing; a fuel inlet port in the elongated fuel valve housing for connecting to a pressurized liquid fuel source; a plunger-type piston accommodated in an inner bore of the valve housing, the inner bore having a plunger chamber; a fuel pipe having an inlet end connected to the fuel inlet port and an outlet end connected to a fuel injection channel; a fuel inlet channel connecting the inlet end of the fuel pipe to the plunger chamber; and a fuel outlet channel connecting the plunger chamber to the outlet end of the fuel pipe.

[0002] The invention also relates to a large turbocharged two-stroke uniflow crosshead internal combustion engine comprising such a fuel valve. Background Art

[0003] Large turbocharged two-stroke single-flow crosshead internal combustion engines are typically used as prime movers in large ocean-going vessels (e.g., container ships) or in power plants. These engines typically run on heavy fuel oil or fuel oil.

[0004] Recently, there has been a need for large two-stroke diesel engines that are capable of processing alternative types of fuels, such as gaseous fuels, for example, methanol, liquefied petroleum gas (LPG), liquefied natural gas (LNG), ethane, ammonia, and / or other similar fuels, because these fuels are relatively clean fuels that, when used as fuel for large, low-speed, single-flow, turbocharged, two-stroke internal combustion engines, result in a higher concentration of sulfur-containing components, NO, in the exhaust gas, compared to, for example, the use of heavy fuel oil as the fuel. x and CO2 content is significantly lower.

[0005] A fuel injection valve of the type mentioned in the introduction is known from US Pat. No. 4,398,519 A.

[0006] It is common to use different fuel valves for different fuel types. Three different known fuel valves are described below, all of which have the same type of disadvantages. Figures 1 to 3 Three different examples of known fuel valves 1 are shown in . Corresponding elements in the three figures are given the same reference numerals.

[0007] Figures 1 to 3The fuel valves 1 shown all comprise an elongated fuel valve housing 2 having a rear end 3 and a front end 4. At the front end of the housing 2 is a nozzle 5 having a plurality of nozzle holes 9 for injecting fuel into a combustion chamber 60. The fuel valve 1 also comprises a fuel inlet port 6 in the elongated fuel valve housing 2 for connection to a pressurized liquid fuel source not shown. The fuel is supplied via a fuel line 7 to a plunger chamber 14 in an inner bore 13 provided in the valve housing 2, and the plunger chamber 14 is defined by an axially displaceable plunger piston 12 accommodated in the inner bore 13, which moves back and forth during filling and emptying of the plunger chamber 14, respectively. The known fuel valves 1 all comprise a fuel injection channel 11 extending from the plunger chamber 14 towards the nozzle 5 at the front end 4 of the fuel valve 1. In order to control the flow of fuel through the fuel valve 1, the fuel valve includes an axially displaceable valve needle 30, which has a closed position and an open position. In the closed position, the axially displaceable valve needle 30 rests on the valve seat 31, preventing fuel from flowing to the nozzle 5, and in the open position, the axially displaceable valve needle 30 is lifted from the valve seat 31, thereby allowing fuel to flow through the fuel valve 1 to the nozzle hole 9.

[0008] The known fuel valve 1 includes a suction valve 40 arranged in the fuel flow path from the fuel inlet port 6 to the plunger chamber 14 , which is opened by the pressure provided by the pressurized fuel during filling of the plunger chamber 14 with fuel.

[0009] If the valve needle 30 becomes stuck during operation, there is a significant risk of over-fueling the combustion chamber of the cylinder, which may cause the cylinder head to lift and may cause engine damage. In order to prevent such over-fueling of the cylinder, Figure 1 The illustrated fuel valve 1 comprises an external ELBI (Electronic Block Injection) valve, not shown, which prevents fuel from being delivered to the fuel valve 1 when fuel should not be delivered to the plunger chamber. Figure 2 and Figure 3 The fuel valves 1 shown both comprise a non-return valve 41 which ensures that fuel can only flow from the plunger chamber 14 via the fuel injection channel 11 to the nozzle 5, but not in the opposite direction to the plunger chamber 14. Furthermore, such a non-return valve 41 ensures that over-fueling of the cylinder does not occur in the event of a stuck valve needle 30.

[0010] about Figure 1 In the fuel valve 1 shown, when the combustion chamber pressure falls below the fuel supply pressure, the ELBI valve shuts off the fuel supply to the fuel valve, thereby preventing overfueling when the valve needle is stuck in the open position. However, the ELBI valve limits the filling time of the injection valve before the next injection and may not prevent cylinder head lift under certain fuel conditions if the trapped volume between the ELBI valve and the fuel valve may contain enough energy to cause cylinder head lift. Figure 2and Figure 3 The fuel valve 1 shown does not monitor the non-return valve during operation, so that if the non-return valve does not function properly and the fuel injection valve becomes stuck in the open position, overfueling and thus cylinder head lift can occur. Summary of the Invention

[0011] It is an object of the present invention to provide a fuel valve of the type mentioned in the introduction, in which the above-mentioned challenges associated with overfueling the combustion chamber are at least significantly reduced.

[0012] The above and other purposes are achieved by the technical solutions disclosed in the present invention. Further implementation forms are obvious from the description and drawings.

[0013] According to a first aspect, a fuel valve is provided for injecting liquid fuel into a combustion chamber of a large turbocharged two-stroke single-flow crosshead internal combustion engine, the fuel valve comprising: an elongated fuel valve housing having a rear end and a front end; a nozzle having a plurality of nozzle holes, the nozzle being arranged at the front end of the housing; a fuel inlet port in the elongated fuel valve housing for connecting to a pressurized liquid fuel source; a plunger-type piston accommodated in an inner bore of the valve housing, the inner bore having a plunger chamber; a fuel pipeline, the fuel pipeline having an inlet end communicating with the fuel inlet port and an outlet end communicating with a fuel injection channel; a fuel inlet channel connecting the inlet end of the fuel pipeline to the plunger chamber; and a fuel outlet port connecting the plunger chamber to the outlet end of the fuel pipeline. inlet channel, and is characterized in that the fuel valve comprises: a spindle valve member capable of moving in the fuel pipeline between at least a first position and a second position, wherein in the first position, the spindle valve member allows fuel to flow through the inlet channel to the plunger chamber to fill the plunger chamber with fuel while preventing fuel from entering the fuel injection channel via the outlet channel, and in the second position, the spindle valve member allows fuel to flow from the plunger chamber to the fuel injection channel through the outlet channel to supply fuel to the nozzle while preventing fuel from entering the plunger chamber via the inlet channel; and a component for providing a certain leakage from the outlet channel to the fuel injection channel when the spindle valve member is in its first position to fill the plunger chamber with fuel.

[0014] Thus, with the fuel valve defined above, a self-checking safety feature is achieved, which ensures that overfueling and, consequently, cylinder head lift cannot occur if the valve needle becomes stuck in the open position. This is achieved by combining the intake valve and the check valve into a single component or valve that can only be in one of two positions: open to fill the plunger chamber with fuel or open to inject fuel from the plunger chamber into the combustion chamber of the cylinder. Thus, there is never a direct, open route from the fuel inlet port to the combustion chamber.

[0015] To prevent fuel from flowing directly from the fuel inlet end of the fuel line through the plunger chamber to the outlet end of the fuel line, the spindle valve member can, in a third intermediate position between the first and second positions, block both fuel from entering the plunger chamber via the inlet passage and from entering the fuel injection passage via the outlet passage. This can be ensured by providing the spindle valve member with a sufficient length to simultaneously block both the inlet and outlet passages of the plunger chamber. The spindle valve member never remains in this third intermediate position.

[0016] The spindle valve member can in principle be constructed in any suitable manner to ensure that the only way for the fuel to flow from the inlet end to the outlet end of the fuel pipeline is via the inlet channel, the plunger chamber and the outlet channel. Therefore, in a simple embodiment, the spindle valve member can be constructed to have a cross-section that fits tightly in the fuel pipeline. However, it is preferred that the spindle valve member is mounted in a fixed housing that is inserted into the fuel pipeline and the spindle valve member is able to move within the housing at least between the first position and the second position. The fixed housing should preferably fit tightly with the fuel pipeline so as to avoid leakage of fuel between the inlet end and the outlet end of the fuel pipeline via any gap or space between the fixed housing and the fuel pipeline. In one embodiment, the assembly can be performed as a press fit.

[0017] During operation of the fuel valve, when the plunger chamber is filled with fuel, the spindle valve member is preferably moved in a direction away from the inlet end of the fuel pipeline towards the outlet end by means of the force provided by the pressurized liquid fuel entering the fuel pipeline via the fuel inlet port, because the pressure at the inlet end of the fuel pipeline is higher than the pressure at the outlet end. Since leakage from the outlet channel to the fuel injection channel is expected when the spindle valve member is in its first position to fill the plunger chamber with fuel, the liquid pressure at the inlet and outlet ends of the fuel pipeline will be equal when the plunger chamber is already filled. Therefore, when it is necessary to supply fuel from the plunger chamber to the fuel injection channel, in order to move the spindle valve member in the opposite direction towards its second position, thereby unblocking the outlet channel of the plunger chamber, the fuel valve according to the present invention may include any suitable components. Therefore, preferably, the fuel valve includes a force applying member for applying a force on the spindle valve member in a direction towards the inlet end of the fuel pipeline. Preferably, the force applying member is a spring.

[0018] Further, it is preferred that the spindle valve member comprises an end stop surface which rests against a corresponding surface provided in the fuel conduit or housing when the spindle valve member is in its second position to allow fuel to flow from the plunger chamber to the fuel injection passage through the outlet passage.

[0019] The means for providing a certain leakage from the outlet passage to the fuel injection passage can, in principle, be any type of means that ensures a certain predetermined flow rate of fuel from the plunger chamber to the fuel injection passage, at least when the spindle valve member is in its first position for filling the plunger chamber with fuel. However, preferably, the means comprises an orifice provided in the spindle valve member. By providing the fuel valve with a leakage means such as an orifice, as described above, when the plunger chamber is fully filled, equal fluid pressure can be achieved at the inlet and outlet ends of the fuel line, thereby enabling a spring or other force-applying member to move the spindle valve member to its second position in the direction of the inlet end of the fuel line.

[0020] Preferably, the orifice is provided in the spindle valve member such that it allows some leakage from the outlet passage to the fuel injection passage only when the spindle valve member is in its first position for filling the plunger chamber with fuel.

[0021] The fuel conduit may in principle be formed with any suitable cross-section, but it is preferred that the fuel conduit is a bore provided in the fuel valve housing.

[0022] The invention also relates to a large turbocharged two-stroke uniflow crosshead internal combustion engine comprising a fuel valve as defined in any one of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will be explained in more detail with reference to exemplary embodiments shown in the accompanying drawings, in which:

[0024] Figure 1 An example of a first known fuel valve is shown,

[0025] Figure 2 An example of a second known fuel valve is shown,

[0026] Figure 3 An example of a third known fuel valve is shown,

[0027] Figure 4 shows an embodiment of a fuel valve according to the present invention,

[0028] Figures 5a to 5c A cross section of a fuel valve according to the invention is shown in more detail. DETAILED DESCRIPTION

[0029] In the following detailed description, the fuel valve according to the invention will be described as being used in a large two-stroke uniflow scavenged internal combustion engine having a crosshead, but it will be understood that the internal combustion engine may be of another type.

[0030] Figure 4 FIG shows a fuel valve 1 according to the present invention. Figures 1 to 3Like the known fuel valve 1 shown, Figure 4 The fuel valve 1 shown comprises an elongated fuel valve housing 2 having a rear end 3 and a front end 4. At the front end of the housing 2 is a nozzle 5 having a plurality of nozzle holes 9 for injecting fuel into a combustion chamber 60. The fuel valve 1 also comprises a fuel inlet port 6 in the elongated fuel valve housing 2 for connection to a pressurized liquid fuel source not shown. The fuel is supplied to a plunger chamber 14 in an inner bore 13 provided in the valve housing 2 via a fuel conduit 7 and a fuel inlet passage 15. The fuel conduit 7 has an inlet end 8 communicating with the fuel inlet port 6 and an outlet end 10. The plunger chamber 14 is defined by the inner bore 13 and an axially displaceable plunger piston 12 accommodated in the inner bore 13, which moves back and forth during filling and emptying of the plunger chamber 14, respectively.

[0031] The fuel valve 1 according to the present invention further includes a fuel injection passage 11, which extends from an outlet end 10 of the fuel line 7 and is supplied with fuel from a plunger chamber 14 via a fuel outlet passage 16, which connects the plunger chamber 14 to the fuel line 7. During the injection of fuel into the combustion chamber 60, the fuel in the plunger chamber 14 is pressurized by means of the plunger piston 12 and flows via the fuel injection passage 11 to the nozzle 5 at the front end 4 of the fuel valve 1. In order to control the flow of fuel through the fuel valve 1, the fuel valve includes an axially displaceable valve needle 30 having a closed position, in which the axially displaceable valve needle 30 rests on a valve seat 31, preventing fuel from flowing to the nozzle 5, and an open position, in which the axially displaceable valve needle 30 is lifted from the valve seat 31, thereby allowing fuel to flow through the fuel valve 1 to the nozzle hole 9. The valve needle 30 is lifted to its open position by the fuel pressurized in the plunger chamber 14 by the plunger piston 12. During fuel injection, this pressurized fuel provides a force acting on the valve needle 30. When fuel injection ends and the fuel pressure in the fuel injection passage 11 is released, the spring 32 forces the valve needle 30 to its closed position.

[0032] As mentioned above, if the valve needle 30 sticks during operation, there is a significant risk that over-fueling of the cylinder's combustion chamber will occur, which may cause the cylinder head to lift and may result in engine damage.

[0033] In order to solve this problem, the fuel valve 1 according to the present invention comprises a spindle valve member 17 which is arranged in the fuel pipe 7 and which can be opened in the fuel pipe 7 in a first position (see Figure 5a ) and the second position (see Figure 5c). In the first position, the spindle valve member 17 is moved in a direction away from the fuel inlet port 6 by means of the pressurized fuel supplied from the fuel source, and allows the fuel to flow into the plunger chamber 14 through the inlet pipe 7 and the inlet channel 15, whereby the fuel is filled into the plunger chamber 14. When the spindle valve member 17 is in the first position, the outlet channel 16 is closed by the spindle valve member 17, thereby preventing the fuel from entering the fuel injection channel 11. In the second position, the spindle valve member 17 is moved in a direction toward the fuel inlet port 6 by means of the spring 18, and allows the fuel to flow from the plunger chamber 14 to the fuel injection channel 11 through the outlet channel 16 to supply the fuel to the nozzle 5. When the spindle valve member 17 is in the second position, the inlet channel 15 is closed by the spindle valve member 17, thereby preventing the fuel from entering the plunger chamber 14 via the inlet channel 15.

[0034] Thus, in the fuel valve 1 according to the present invention, the intake valve and the check valve employed in known fuel valves are combined into a single part or valve that can only be in one of two positions, namely, open to fill the plunger chamber 14 with fuel or open to inject fuel from the plunger chamber 14 into the combustion chamber 60 of the cylinder. Consequently, there is never a direct open route from the fuel inlet port 6 to the combustion chamber 60, which ensures that overfueling and, consequently, cylinder head lift will not occur if the valve needle becomes stuck in the open position.

[0035] The fuel valve 1 according to the present invention includes an orifice 21 which provides a certain leakage from the outlet passage 16 to the outlet end 10 of the fuel line and the fuel injection passage 11 when the spindle valve member 17 is in its first position for filling the plunger chamber 14 with fuel. By providing the fuel valve with a leakage feature such as the orifice 21, when the plunger chamber 14 has been filled, the liquid pressure at the inlet end 8 and the outlet end 10 of the fuel line 7 will be equal, thereby enabling the spring 18 or other force-applying member to move the spindle valve member 17 in the direction of the inlet end 8 of the fuel line 7 to its second position.

[0036] Reference Figures 5a to 5c , the fuel valve 1 according to the present invention is explained in more detail. As can be seen in the figure, the spindle valve member 17 is mounted in a fixed housing 20, which is inserted into the fuel pipe 7. The spindle valve member 17 is movable within the housing 20 between the mentioned first position and the second position, and comprises a spring 18 for exerting a force on the spindle valve member 17 in the direction towards the inlet end of the fuel pipe 7. The spindle valve member 17 comprises an end stop surface 25, which is formed when the spindle valve member 17 is in its second position (as shown in FIG. Figure 5c As shown in FIG. 1 , the end stop surface rests on a corresponding surface 26 provided in the stationary housing 20 when the plunger chamber 14 is moved to allow fuel to flow from the plunger chamber 14 to the fuel injection passage 11 through the outlet passage 16 .

[0037] In the embodiment shown, the fuel conduit 7 is provided as an inner hole 7 in the fuel valve housing 2, and the fixed housing 20 is provided as a cylindrical body, with two ends 37 and 38 of the fuel conduit 7 being open, namely at the inlet end 8 and the outlet end 10 of the fuel conduit 7. The fixed housing 20 is provided with two annular recesses 33 and 34, which are arranged to communicate with the inlet channel 15 and the outlet channel 16, respectively. At the bottom of the two annular recesses 33 and 34, the fixed housing 20 is provided with a plurality of holes 35 and 36, respectively. When the spindle valve member 17 is in Figure 5a In the first position shown, the hole 35 allows liquid fuel to flow from the inlet end 8 of the fuel pipe 7 through the open end 37 of the housing 20 at the inlet end 8 to the annular recess 33 and further through the inlet passage 15 to the plunger chamber 14, while when the spindle valve member 17 is in the Figure 5c In the second position shown, the aperture 36 allows liquid fuel to flow from the plunger chamber 14 through the outlet passage 16 to the annular recess 34 , through the aperture 36 , and further through the open end 38 of the housing 20 to the outlet end 10 of the fuel conduit 7 .

[0038] exist Figure 5b , spindle valve member 17 is shown in a third, intermediate position between the first and second positions. Spindle valve member 17 is in this intermediate position both when moving toward its first position and when moving toward its second position, but never rests or remains stationary in this intermediate position. In this intermediate position, spindle valve member 17 blocks both fuel from entering plunger chamber 14 via inlet passage 15 and from entering fuel injection passage 11 via outlet passage 16. This further ensures that a direct, open route from fuel inlet port 6 to combustion chamber 60 never exists.

Claims

1. A fuel valve (1) for injecting liquid fuel into a combustion chamber of a large turbocharged two-stroke single-flow crosshead internal combustion engine, the fuel valve (1) comprising: An elongated fuel valve housing (2) having a rear end (3) and a front end (4); A nozzle (5) having a plurality of nozzle holes (9), the nozzle (5) being arranged at the front end (4) of the elongated fuel valve housing (2); a fuel inlet port (6) in the elongated fuel valve housing (2) for connection to a source of pressurized liquid fuel; a plunger-type piston (12) housed in an inner bore (13) of the elongated fuel valve housing (2), the inner bore (13) having a plunger chamber (14); a fuel pipe (7), the fuel pipe having an inlet end (8) communicating with the fuel inlet port (6) and an outlet end (10) communicating with a fuel injection passage (11); a fuel inlet passage (15) connecting the inlet end (8) of the fuel pipe (7) to the plunger chamber (14); and a fuel outlet passage (16) connecting the plunger chamber (14) to the outlet end (10) of the fuel pipe (7), wherein the fuel valve comprises: a nozzle (5) capable of being connected to the fuel pipe (7) A spindle valve member (17) is movable between at least a first position and a second position, wherein in the first position, the spindle valve member (17) allows fuel to flow through the fuel inlet passage (15) to the plunger chamber (14) to fill the plunger chamber (14) with fuel while preventing fuel from entering the fuel injection passage (11) via the fuel outlet passage (16), and in the second position, the spindle valve member (17) allows fuel to flow from the plunger chamber (14) to the fuel injection passage (11) through the fuel outlet passage (16) to supply fuel to the nozzle (5) while preventing fuel from entering the plunger chamber (14) via the fuel inlet passage (15); and a component for providing a certain leakage from the fuel outlet passage (16) to the fuel injection passage (11) only when the spindle valve member (17) is in its first position to fill the plunger chamber (14) with fuel.

2. The fuel valve (1) according to claim 1, characterized in that In a third intermediate position between the first position and the second position, the spindle valve member (17) blocks fuel from entering the plunger chamber (14) via the fuel inlet passage (15) and from entering the fuel injection passage (11) via the fuel outlet passage (16).

3. The fuel valve (1) according to claim 1 or 2, characterized in that The spindle valve member (17) is mounted in a stationary housing (20) which is inserted into the fuel pipe (7), and the spindle valve member (17) is movable within the stationary housing (20) between at least the first position and the second position.

4. The fuel valve (1) according to claim 1 or 2, characterized in that The fuel valve comprises a force applying member (18) for applying a force on the spindle valve member (17) in a direction towards the inlet end of the fuel conduit (7).

5. The fuel valve (1) according to claim 4, characterized in that The force applying member is a spring (18).

6. The fuel valve (1) according to claim 1 or 2, characterized in that The spindle valve member (17) includes an end stop surface which rests against a corresponding surface provided in the fuel conduit (7) or a fixed housing (20) in which the spindle valve member (17) is mounted when the spindle valve member (17) is in its second position to allow fuel to flow from the plunger chamber (14) to the fuel injection passage (11) through the fuel outlet passage (16).

7. The fuel valve (1) according to claim 1, characterized in that The means for providing a certain leakage from the fuel outlet passage (16) to the fuel injection passage (11) comprises an orifice (21) provided in the spindle valve member (17).

8. The fuel valve (1) according to claim 7, characterized in that The orifice (21) is arranged in the spindle valve member (17) so that it generates a certain leakage from the fuel outlet passage (16) to the fuel injection passage (11) only when the spindle valve member (17) is in its first position to fill the plunger chamber (14) with fuel.

9. The fuel valve (1) according to any one of claims 1, 2, 7 and 8, characterized in that The fuel conduit (7) is an inner hole provided in the elongated fuel valve housing (2).

10. A large turbocharged two-stroke single-flow crosshead internal combustion engine comprising a fuel valve (1) according to any one of claims 1 to 9.

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