Fuel injection system for dual fuel internal combustion engine and dual fuel internal combustion engine

Abstract

To provide a new-type fuel injector of a dual-fuel internal combustion engine, and to provide an internal combustion engine including the same.SOLUTION: A fuel injector 16 of a dual-fuel internal combustion engine is designed in order to feed fuel to a combustion chamber 33 of a cylinder 12 of the dual-fuel internal combustion engine, having a main body 27, having a nozzle needle 28 that is movably guided in a needle guide 30 of the main body, having a needle fuel chamber 31 defined by the main body, which can be coupled to the combustion chamber of the cylinder via orifices 32, where the orifices are open in a first position of the nozzle needle and closed in a second position of the nozzle needle, where a first line 34 is coupled to the needle fuel chamber, where via the first line a fuel can be introduced into the needle fuel chamber, and where a second line 35 that is separated from the first line is formed in the main body, which on the one hand is couple to the needle guide and on the other hand to a control chamber 36 of a control valve 29 of the fuel injector 16, where via the second line a fuel can be fed to the needle guide as barrier fluid and to the control chamber as working fluid.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a fuel injection device for a dual fuel internal combustion engine.The present invention further relates to a dual fuel internal combustion engine.

[0002] The invention presented here relates to the field of so-called large engines or large internal combustion engines, whose cylinders have a piston diameter of at least 140 mm, in particular at least 175 mm. Such large internal combustion engines are, for example, marine engines. [Background technology]

[0003] Dual-fuel internal combustion engines as marine engines are already known. In practice, known dual-fuel internal combustion engines can be operated in a first operating mode in which a liquid fuel is burned and in a second operating mode in which a gaseous fuel or another liquid fuel is burned.

[0004] From DE 10 200 03 133 A1 a dual-fuel internal combustion engine is known, which is equipped with a dual fuel injector. The respective fuels are fed towards the dual fuel injector via separate fuel pumps. In addition, separate sealing and lubrication systems are present. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] German Patent Publication No. 102017123315 Summary of the Invention [Problem to be solved by the invention]

[0006] Starting from here, the present invention has been made with the object of providing a new type of fuel injection device for a dual-fuel internal combustion engine, and a dual-fuel internal combustion engine having such a fuel injection device. [Means for solving the problem]

[0007] This object is solved by a fuel injection device according to claim 1.

[0008] The fuel injector is configured to supply liquid fuel to a combustion chamber of a cylinder of a dual fuel internal combustion engine and comprises a body, a nozzle needle movably guided in a needle guide of the body, and a needle fuel chamber defined by the body and connectable to the combustion chamber of the cylinder through an orifice, the orifice being open in a first position of the nozzle needle and closed in a second position of the nozzle needle.

[0009] A first line extends through the body and connects to a needle fuel chamber, allowing fuel to be introduced into the needle fuel chamber through the first line.

[0010] Furthermore, a second line separate from the first line is introduced into the body of the fuel injection device, and the second line is connected to the needle guide on the one hand and to a control chamber of a control valve of the fuel injection device on the other hand, and fuel can be supplied to the needle guide as a barrier fluid and to the control chamber as an actuating fluid via the second line.

[0011] The fuel injection device according to the invention allows a particularly advantageous fuel injection into the combustion chambers of each cylinder of a dual-fuel internal combustion engine burning liquid fuel, in an operating mode of the dual-fuel internal combustion engine, in which fuel can be injected via the fuel injection device into the combustion chambers of each cylinder, with the other fuel acting preferentially as barrier fluid and working fluid, i.e. the fuel introduced into each combustion chamber of each cylinder in the other operating mode, resulting in a particularly simple construction of the fuel injection device.

[0012] In a further development, the fuel injection device is a dual-fuel injection device, such that in a first operating mode of the dual-fuel internal combustion engine a first fuel, which is relatively easy to ignite, can be supplied to the first line and to the second line, respectively, and in a second operating mode of the dual-fuel internal combustion engine, the first fuel can be supplied to the second line and a second fuel, which is relatively difficult to ignite, can be supplied to the first line. Such a dual-fuel injection device is particularly preferred and allows a particularly simple construction of the dual-fuel internal combustion engine.

[0013] According to a further development of the invention, the second line is connected to the control chamber of the control valve via a choke, which is preferable for supplying the respective fuel to the control chamber of the control valve.

[0014] The dual fuel internal combustion engine according to the invention is defined in claim 6.

[0015] Preferred further developments of the invention emerge from the dependent claims and the following description. Exemplary embodiments of the invention are explained in detail with reference to the drawings, in which: [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a schematic diagram of a marine propulsion system including a dual-fuel internal combustion engine. [Diagram 2] 1 is a diagram showing a portion of a cylinder of a dual fuel internal combustion engine; [Diagram 3] 1 is a cross-sectional view of a fuel injection system for a dual-fuel internal combustion engine; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] FIG. 1 shows, highly diagrammatically, a marine propulsion system 10 including a dual fuel internal combustion engine 11 having a number of cylinders 12 .

[0018] In the cylinders 12, fuel is combusted. In a first operating mode of the dual-fuel internal combustion engine 11, the fuel is a first liquid fuel, and in a second operating mode of the dual-fuel internal combustion engine 11, the fuel is a second liquid fuel. During the combustion of the respective fuel, the dual-fuel internal combustion engine 11 generates a driving force, which in FIG. 1 is utilized to drive a generator 13. In the generator 13, electrical energy is generated and is used to drive a propeller 14 of the vessel.

[0019] Furthermore, Fig. 1 shows a fuel supply system 15 of the dual-fuel internal combustion engine 11. Fig. 2 and Fig. 3 show further assemblies of the fuel supply system 15. By means of the fuel supply system 15, the respective liquid fuels can be supplied to the cylinders 12 of the dual-fuel internal combustion engine 11 in the respective operating modes. This fuel supply system 15 of the dual-fuel internal combustion engine 11 comprises a main injection system and a pilot injection system.

[0020] A main injection system (see Figures 2 and 3) including at least one main injector 16 for each cylinder 12 allows the cylinders 12 to be supplied with a first liquid fuel that is relatively easy to ignite in a first operating mode and a second liquid fuel that is relatively difficult to ignite in a second operating mode. The main injectors 16 allow the first liquid fuel to be injected into each cylinder 12 in the first operating mode and the second liquid fuel to be injected into the same cylinder 12 in the second operating mode. Although for cost reasons it is preferred to inject the first liquid fuel in the first operating mode and the second liquid fuel in the second operating mode into each cylinder 12 of a dual-fuel internal combustion engine via the same type injector 16, it is also possible for each cylinder 12 to have separate main injectors for each of the two liquid fuels.

[0021] The illustrated embodiment is a preferred example in which the same main fuel injector 16 is utilized in a first mode of operation to inject a first liquid fuel and a second mode of operation to inject a second liquid fuel into the cylinders.

[0022] According to Fig. 2, the respective liquid fuel is supplied to the respective main injector 16 via a main pump 17. The main pump 17 thus supplies a first liquid fuel to the respective main injector 16 in a first operating mode and a second liquid fuel to the respective main injector 16 in a second operating mode.

[0023] 1 shows a first fuel tank 18 for holding a first liquid fuel and a second fuel tank 19 for holding a second liquid fuel. The first fuel tank 18 can be connected via a first fuel line 20 and the second fuel tank 19 via a second fuel line 21 to the main pump 17, i.e. via a shuttle valve 22.

[0024] In a first operating mode, the shuttle valve 22 connects the first fuel tank 18 or the first fuel line 20 to the main pump 17 of the main injection system for supplying the first fuel 18 to the cylinders 12 of the dual-fuel internal combustion engine 11. In this first operating mode, the shuttle valve 22 isolates the second fuel tank 19 from the main pump 17 of the main injection system.

[0025] In contrast, in the second operating mode, the shuttle valve 22 assumes a switching position in which the second fuel tank 19 is connected via the second fuel line 21 to the main pump 17 of the main injection system in order to supply the second fuel to the cylinders 12 of the dual-fuel internal combustion engine 11. In this second operating mode, the first fuel tank 18 is thus isolated from the main pump 17 of the main injection system.

[0026] As already explained, the first liquid fuel has a relatively good ignitability and the second liquid fuel has a relatively poor ignitability. In order to ignite the second liquid fuel in the region of each cylinder 12 in the second operating mode, the dual-fuel internal combustion engine is provided with a pilot injection system including at least one pilot injector 23 for each cylinder 12.

[0027] By means of the pilot injection system, a first liquid fuel for igniting a second liquid fuel in a second operating mode can be supplied to the cylinders 12 of the internal combustion engine. The pilot injection system therefore comprises at least one pilot injector 23 for each cylinder 12 as well as a pilot pump 24, via which the respective pilot injector 23 is supplied with a first liquid fuel discharged from a first fuel tank 18 in the second operating mode. From the first fuel tank 18 a further fuel line 40 runs in the direction of the cylinders 12, to which the pilot pump 24 is connected.

[0028] As can be seen from FIG. 2 for the dual-fuel internal combustion engine 11, the main injection system and the pilot injection system are coupled in such a way that, in the second operating mode, a first liquid fuel is supplied to each main injector 16 of the main injection system, emanating from a pilot injection system having at least one pilot injector 23 and a pilot pump 24 for each cylinder 12, where the first liquid fuel also serves as working fluid and barrier fluid in the region of each main injector 16. FIG. 2 therefore shows branch lines 25 which branch off from the pilot injection system upstream of the respective pilot injector 23, lead to each main injector 16 of the main injection system of each cylinder 12 and are connected to the main injection system in the region of each main injector 16. In the second operating mode, in order to supply a first liquid fuel as working fluid and barrier fluid to each main injector 16 of the main injection system, a branch line 25 branches off from the pilot injection system downstream of the pilot pump 24 and upstream of each pilot injector 23, as viewed in the supply direction of the pilot injection system.

[0029] In the second operating mode, a predefined pressure is present in each branch line 25 leading from the pilot injection system to the main injection system, which pressure is greater than the pressure in the area of ​​each main injector 16 by a preferably defined pressure offset, thereby ensuring that in the second operating mode, the first liquid fuel is always supplied to each main injector 16.

[0030] 2, as shown, a pressure reducer 26 is incorporated into the branch line 25. This limits the pressure in the branch line 25 downstream of the pressure reducer 26 to a specified level.

[0031] The relatively easy-to-ignite first liquid fuel is preferably a liquid fuel having a lubricity WSD of 100 μm to 300 μm, more preferably 100 μm to 200 μm. The relatively difficult-to-ignite second liquid fuel is preferably a liquid fuel having a lubricity WSD of 300 μm to 820 μm, more preferably 400 μm to 820 μm. Preferentially, the first liquid fuel is diesel fuel. Preferentially, the second liquid fuel is ethanol or methanol.

[0032] In a dual-fuel internal combustion engine 11 which burns the respective liquid fuel in both operating modes, the first liquid fuel in the second operating mode serves on the one hand to ignite the second liquid fuel and on the other hand as working fluid and barrier fluid in the region of the respective main injector 16. Thus, the main injector 16 and the pilot injector 23 of each cylinder 12 utilize the first liquid fuel in the second operating mode on the one hand as ignition fluid introduced into the respective cylinder 12 via the respective pilot injector 23 and on the other hand as working fluid and barrier fluid in the region of the main injector 16 of each cylinder.

[0033] FIG. 3 is a schematic cross-sectional view of a main injector 16 of a dual fuel internal combustion engine 11 constructed in accordance with the present invention.

[0034] The fuel injector 16 preferably includes a multi-part body 27 , a nozzle needle 28 , and a control valve 29 .

[0035] The nozzle needle 28 is movably guided in a needle guide 30 in the body 27. The body 27 defines a needle fuel chamber 31. The needle fuel chamber 31 is connectable via an orifice 32 to a combustion chamber 33 of each cylinder 12. In a first position, the nozzle needle 28 closes the orifice 32 and in a second position, the nozzle needle 28 opens the orifice 32.

[0036] A first line 34 leads into the body 27. Via this first line 34 fuel can be supplied to the needle fuel chamber 31.

[0037] In the embodiment shown, in which the main injector 16 is a dual fuel injector of a dual fuel internal combustion engine 11, a first fuel which is relatively easy to ignite, discharged from a first fuel tank 18, can be supplied via the main pump 17 to the needle fuel chamber 31 of the main injector 16 via a first line 34 in a first operating mode of the dual fuel internal combustion engine 11. In a second operating mode of the dual fuel internal combustion engine 11, a relatively hard to ignite fuel which is discharged from a second fuel tank 19, can be supplied via the main pump 17 to the needle fuel chamber 31 of the main injector 16 via the first line 34. As explained above, in this respect the shuttle valve 22 assumes the respective switching position.

[0038] In addition to the first line 34, a second line 35 separate from the first line 34 is introduced into the body 27. By means of this second line 35, in the second operating mode of the dual-fuel internal combustion engine 11, the first fuel can be supplied on the one hand to the needle guide 30 and on the other hand to the control chamber 36 of the control valve 29 of the main injector 16. The first fuel discharged from the pilot injection system can be supplied via a branch line 25 shown in FIG. 2. The branch line 25 branches the first fuel downstream of the pilot pump 24 and upstream of the pilot injector 23 in the direction of the main injector 16, i.e. in the direction of a second line 35 of said main injector. The first fuel supplied via the second line 35 to the needle guide 30 acts there as a barrier fluid. The first fuel supplied via the first line 35 to the control chamber 36 of the control valve 29 acts there as a working fluid. This fuel, which acts as a working fluid, may be supplied to the control chamber 36 via a choke 37 which leads to the control chamber 36 .

[0039] 2, the pressure in the branch line 25, and therefore in the second line 35, is greater than the pressure in the first line 34. Thus, via the barrier fluid in the region of the needle guide 30, a particularly advantageous barrier effect is provided.

[0040] The fuel conducted in the fuel injector according to the invention via the second line 35 thus serves as a barrier fluid on the one hand and as a working fluid on the other hand, which allows a particularly simple construction of the fuel injector 16 and of the dual-fuel internal combustion engine 11 equipped with it. In the second operating mode, in which a second fuel is burned in the cylinder 12, a simple separation is possible between the second fuel to be burned and the first fuel which serves as barrier fluid and working fluid.

[0041] According to FIG. 3, the needle guide 30 is disposed between the needle fuel chamber 31 and the control chamber 36 of the control valve 29 .

[0042] A spring chamber 38 is disposed between the needle guide 30 and the control chamber 36 and receives a spring 39 which urges the nozzle needle 28 into the second position.

[0043] The invention applies in particular to the field of so-called large engines or large internal combustion engines, whose cylinders have a piston diameter of at least 140 mm, in particular at least 175 mm. Such large internal combustion engines are, for example, marine engines. In the context of the invention, these are embodied as dual-fuel internal combustion engines. [Explanation of symbols]

[0044] 10. Ship Propulsion System 11 Dual-fuel internal combustion engine 12 cylinders 13. Generator 14 Ship Propeller 15 Fuel supply system 16 Main injector 17 Main pump 18,19 Fuel tank 20,21 Fuel lines 22 Shuttle valve 23 Pilot Injector 24 Pilot pump 25 Branch Line 26 Pressure reducer 27 Main Body 28 Nozzle Needle 29 Control valve 30 Needle Guide 31 Needle fuel chamber 32 Orifice 33 Combustion chamber 34,35 lines 36 Control Chamber 37 Chalk 38 Spring chamber 40 Fuel Line

Claims

1. A fuel injection device (16) for a dual-fuel internal combustion engine (11) configured for supplying fuel to a combustion chamber (33) of a cylinder (12) of the dual-fuel internal combustion engine (11), comprising: A main body (27); a nozzle needle (28) movably guided in a needle guide (30) of said body (27); a needle fuel chamber (31) defined by said body (27), said needle fuel chamber (31) being connectable to a combustion chamber (33) of a cylinder (12) through an orifice (32) that is open in a first position of said nozzle needle (28) and that is closed in a second position of said nozzle needle (28); Equipped with A first line (34) connected to a needle fuel chamber (31) is introduced into the body (27), and fuel can be introduced into the needle fuel chamber (31) through the first line (34); a second line (35) separate from the first line (34) is introduced into the body (27), the second line (35) being connected to the needle guide (30) on the one hand and to a control chamber (36) of a control valve (29) of a fuel injection device (16) on the other hand, such that fuel can be supplied to the needle guide (30) as a barrier fluid and to the control chamber (36) as a working fluid via the second line (25); the fuel injection system is a dual fuel injection system, In a first operating mode of the dual-fuel internal combustion engine, a first fuel, which is relatively easy to ignite, can be supplied to the first line (34) and the second line (35), respectively; In a second operating mode of the dual fuel internal combustion engine, the first fuel may be supplied to the second line (35) and a second fuel, which is relatively difficult to ignite, may be supplied to the first line (34). Fuel injection device.

2. 2. A fuel injection system according to claim 1, wherein the second line (35) is connected to the control chamber (36) of the control valve (29) via a choke (37).

3. 3. A fuel injection system as claimed in claim 1 or 2, wherein the needle guide (30) is arranged between the needle fuel chamber (31) and the control chamber (36) of the control valve (29).

4. 4. The fuel injection device of claim 3, further comprising a spring chamber (38) disposed between the needle guide (30) and the control chamber (36), the spring (39) being disposed within the spring chamber (38) and biasing the nozzle needle (28) to the second position.

5. A dual-fuel internal combustion engine (11), a plurality of cylinders (12) capable of combusting a first liquid fuel in a first mode of operation and a second liquid fuel in a second mode of operation; a main injection system including at least one main injector (16) for each cylinder (12), via which the first liquid fuel can be supplied to the cylinder (12) in the first operating mode and the second liquid fuel can be supplied to the cylinder (12) in the second operating mode, each main injector (16) being a fuel injection device according to any one of claims 1 to 4; a pilot injection system including at least one pilot injector (23) for each cylinder (12), via which, in a second operating mode, the first liquid fuel for igniting a second liquid fuel can be supplied to the cylinders (12) of the internal combustion engine; A dual fuel internal combustion engine (11).

6. 6. The dual fuel internal combustion engine (11) of claim 5, wherein the main injection system and the pilot injection system are connected such that in the second operating mode, a first liquid fuel discharged from the pilot injection system can be supplied to each main injector (16) as an actuating fluid and a barrier fluid.

7. 7. A dual-fuel internal combustion engine (11) according to claim 5 or 6, characterized in that upstream of each pilot injector (23), a branch line (25) branches off from the pilot injection system respectively and leads to the second line (35) of each main injector (16).

8. 8. A dual fuel internal combustion engine (11) according to claim 7, characterized in that each branch line (25) is fitted with a respective pressure reducing valve (26) for limiting the pressure in each branch line (25).

9. the main injection system comprises a main pump (17) via which the first liquid fuel can be supplied to the cylinder (12) in the first operating mode and the second liquid fuel can be supplied to the cylinder (12) in the second operating mode; the pilot injection system comprises a pilot pump (24) via which, in a second operating mode, the first liquid fuel for igniting the second liquid fuel can be supplied to the cylinder (12); 9. The dual fuel internal combustion engine (11) according to any one of claims 5 to 8, wherein a shuttle valve (22) connects the main pump (17) to a first fuel tank (18) for the first liquid fuel in the first operating mode and connects the main pump (17) to a second fuel tank (18) for the second liquid fuel in the second operating mode.

Images