Fuel injector for a dual-fuel internal combustion engine, dual-fuel internal combustion engine and method of operating the same
By designing a dual-fuel injector that includes a nozzle needle and a needle fuel chamber, efficient fuel injection is achieved in different operating modes using two pipeline systems and control valves. This solves the problems of complex structure and low injection efficiency in existing technologies, and realizes a simple structure and efficient fuel injection for internal combustion engines.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- EVERLLENCE SE
- Filing Date
- 2021-10-22
- Publication Date
- 2026-06-30
AI Technical Summary
Existing dual-fuel internal combustion engines require separate fuel pumps and sealing systems, resulting in complex structures and a lack of a fuel injector capable of efficiently injecting liquid fuel in different operating modes.
A fuel injector was designed, comprising a body, a nozzle needle, and a needle fuel chamber. It injects relatively flammable and non-flammable liquid fuels through two independent pipeline systems in different operating modes. Precise fuel control is achieved by using a choke and a control valve, eliminating the need for a separate ignition injector.
It achieves a simple structure and efficient fuel injection in a dual-fuel internal combustion engine, enabling liquid fuel to be injected separately or together in different operating modes, thus improving the operational flexibility and efficiency of the internal combustion engine.
Smart Images
Figure CN114382623B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a fuel injector for a dual-fuel internal combustion engine. Furthermore, this invention relates to a dual-fuel internal combustion engine and a method for operating it. Background Technology
[0002] In particular, the present invention 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, and especially at least 175 mm. Such large internal combustion engines are, for example, marine engines.
[0003] Dual-fuel internal combustion engines are known as marine engines. According to practical experience, dual-fuel internal combustion engines can operate in a first operating mode in which they burn a liquid fuel and in a second operating mode in which they burn a gaseous fuel or another liquid fuel.
[0004] According to DE 10 2017 123 315 A1, a dual-fuel internal combustion engine with dual fuel injectors is known. Each fuel is delivered via a separate fuel pump in the direction of the dual fuel injectors. Furthermore, separate sealing and lubrication systems are present. Summary of the Invention
[0005] From this point forward, the present invention is based on the objective of creating a novel fuel injector for a dual-fuel internal combustion engine and a dual-fuel internal combustion engine having such a fuel injector.
[0006] This objective is achieved by a fuel injector according to an embodiment of the present invention.
[0007] The fuel injector is designed to feed liquid fuel into the combustion chamber of a cylinder in a dual-fuel internal combustion engine. The fuel injector includes a body, a nozzle needle movably guided in a needle guide within the body, and a needle fuel chamber defined by the body, the needle fuel chamber being coupled to the combustion chamber via an opening that is open in a first position of the nozzle needle and closed in a second position of the nozzle needle.
[0008] A first line connected to the needle fuel chamber is introduced into the body of the fuel injector, through which a first liquid fuel can be introduced into the needle fuel chamber. Furthermore, a second line, separate from the first line, is introduced into the body of the fuel injector and also connected to the needle fuel chamber, through which a second liquid fuel can be introduced into the needle fuel chamber.
[0009] The fuel injector according to the invention allows for particularly advantageous fuel injection into the combustion chamber of the corresponding cylinder of a dual-fuel internal combustion engine that burns liquid fuel. In a defined operating mode of the dual-fuel internal combustion engine, the liquid relative to non-flammable fuel can be injected into the combustion chamber of the corresponding cylinder via the fuel injector, i.e., together with another liquid relative to combustible fuel used to ignite the relative non-flammable liquid fuel. In another defined operating mode, the fuel injector is specifically designed to introduce the relative combustible liquid fuel into the corresponding combustion chamber of the corresponding cylinder. Thus, the fuel injector according to the invention acts as a main injector and also as a ignition injector. A separate ignition injector can be omitted. This allows for a simpler construction of the internal combustion engine.
[0010] Preferably, the second line is connected to the needle fuel chamber via a control element such as, for example, a choke, so as to feed relatively flammable liquid fuel into the needle fuel chamber in a defined manner, particularly when the liquid relatively non-flammable fuel is introduced into the needle fuel chamber via the first line.
[0011] According to a further development of the invention, a second line is further connected to the needle guide and / or to the control chamber of the control valve of the fuel injector, wherein the liquid relative to the combustible fuel can be fed via the second line to the needle guide as a barrier fluid and / or to the control chamber as a working fluid. Thus, the relative combustible liquid fuel also acts as a barrier fluid and / or a working fluid. This allows for a particularly simple engine configuration. Preferably, the second line is connected to the control chamber of the control valve via another choke. This is preferred so as to feed the relative combustible fuel to the control chamber of the control valve in a defined manner.
[0012] This disclosure defines a dual-fuel internal combustion engine according to the invention and a method for operating the dual-fuel internal combustion engine. Attached Figure Description
[0013] Preferred further improvements of the invention are obtained from this disclosure. Exemplary embodiments of the invention are explained in more detail with reference to the accompanying drawings, but are not limited thereto. The drawings show:
[0014] Figure 1 This is a schematic diagram of a ship propulsion system with a dual-fuel internal combustion engine;
[0015] Figure 2 It is the cross-section of the fuel injector passing through the dual-fuel internal combustion engine;
[0016] Figure 3 This is a first-time diagram used to illustrate a method for operating a dual-fuel internal combustion engine;
[0017] Figure 4 This is a second time diagram used to illustrate a method for operating a dual-fuel internal combustion engine. Detailed Implementation
[0018] Figure 1 The ship propulsion system 10 is shown schematically, which includes a dual-fuel internal combustion engine 11 with multiple cylinders 12.
[0019] In cylinder 12, fuel combustion occurs, namely, liquid-to-combustible fuel in the first operating mode of the dual-fuel internal combustion engine 11 and liquid-to-non-combustible fuel in the second operating mode of the dual-fuel internal combustion engine 11.
[0020] During the combustion of the corresponding fuel, the dual-fuel internal combustion engine 11 generates driving power, which in turn... Figure 1 The generator 13 is used to drive the propeller 14 of the ship. The generator 13 generates electrical energy, which is used to drive the ship's propeller 14.
[0021] also, Figure 1 The fuel supply system 15 of the dual-fuel combustion engine 11 is shown. Figure 2 The fuel injector 16 according to the invention is shown as a component of the fuel supply system 15.
[0022] Through the fuel supply system 15, the corresponding liquid fuel can be fed to the cylinder 12 of the dual-fuel internal combustion engine 11 in the corresponding operating mode.
[0023] For each cylinder 12, the fuel supply system 15 includes at least one fuel injector 16, particularly a single fuel injector 16.
[0024] In the first operating mode of the dual-fuel internal combustion engine 11, relatively combustible liquid fuel can be fed to the corresponding cylinder 12 via the fuel injector 16. Furthermore, in the second operating mode of the dual-fuel internal combustion engine 11, relatively non-combustible liquid fuel and relatively combustible liquid fuel used to ignite the relatively non-combustible liquid fuel can be fed to the corresponding cylinder 12 via the fuel injector 16.
[0025] Therefore, the same fuel injector 16 of the corresponding cylinder 12 is used to introduce the corresponding liquid fuel into the corresponding cylinder 12 in both the first operating mode and the second operating mode. That is, in the first operating mode, it is used to specifically introduce combustible fuel, and in the second operating mode, it is used to ignite non-combustible liquid fuel and combustible liquid fuel used to ignite the non-combustible liquid fuel. Thus, the same fuel injector 16 acts as both the main injector and the ignition injector.
[0026] Figure 2A fuel injector 16 according to the invention is shown in more detail. As already explained, this fuel injector 16 is used to introduce relatively combustible liquid fuel into a corresponding cylinder in a first operating mode and to introduce relatively non-combustible liquid fuel together with the relatively combustible liquid fuel into the corresponding cylinder in a second operating mode, wherein in the second operating mode, the relatively combustible liquid fuel is used to ignite the relatively non-combustible liquid fuel.
[0027] The fuel injector 16 includes a preferably multi-part body 27, a nozzle needle 28, and a control valve 29.
[0028] The nozzle needle 28 is movably guided within the needle guide 30 of the body 27. The body 27 defines a needle fuel chamber 31. This needle fuel chamber 31 can be connected to the combustion chamber 33 of the corresponding cylinder 12 via an opening 32. In a first position, the nozzle needle 28 closes the opening 32. In a second position, the nozzle needle 28 opens the opening 32.
[0029] A first line 34 is introduced into the body 27 of the fuel injector 16 according to the invention. This first line 34 is connected to a needle fuel chamber 31, through which a first liquid fuel can be introduced.
[0030] In addition to the first line 34 connected to the needle fuel chamber 31, a second line 35, separate from the first line 34, is also introduced into the body 27, and is connected to the needle fuel chamber 31 independently of the first line 34. Second fuel can be introduced into the needle fuel chamber 31 via this second line 35.
[0031] When the first conduit 34 leads to the portion 31b of the needle fuel chamber 31 spaced apart from the opening 32, the second conduit 35 leads to the portion 31b of the needle fuel chamber 31 adjacent to the opening 32. The needle fuel chamber 31 can be connected to the combustion chamber 33 of the corresponding cylinder 12 via the opening 32. Therefore, when the second conduit 35 leads to the needle fuel chamber 31 adjacent to the opening 32, the first conduit 34 leads to the needle fuel chamber 31 with a clear gap from the opening 32. The two portions 31a and 31b of the needle fuel chamber 31 are connected to each other via a choke-like contraction 40.
[0032] In the first operating mode of the dual-fuel internal combustion engine 11, the combustible liquid fuel can be fed to the first line 34 as the first fuel and to the second line 35 as the second fuel in each case. Therefore, in the first operating mode, the combustible liquid fuel is fed to the two partial chambers 31a and 31b of the needle fuel chamber 31.
[0033] In the second operating mode of the dual-fuel internal combustion engine 11, a relatively non-flammable fuel, serving as the first fuel, can be fed to the first line 34, and a relatively flammable liquid fuel, serving as the second liquid fuel, is fed to the second line 35. In this second operating mode, the relatively flammable liquid fuel is used to ignite the relatively non-flammable fuel. Therefore, the relatively flammable liquid fuel is fed to a portion 31a of the needle fuel chamber 31, and the relatively non-flammable liquid fuel is fed to a portion 31b of the needle fuel chamber 31.
[0034] Figure 1 A fuel tank 18 is shown in which a relatively flammable liquid fuel is held.
[0035] In the first operating mode, the relatively flammable liquid fuel is fed to the first line 34 of the corresponding fuel injector 16 via the first fuel pump 17 (which may also be referred to as the main pump). In addition, in the first operating mode, the relatively flammable liquid fuel originating from the fuel tank 18 is fed to the second line 35 of the corresponding fuel injector 16 via the second fuel pump 24 (which may also be referred to as the ignition pump).
[0036] The pressure provided by the second fuel pump 24 is preferably slightly higher than the pressure provided by the first fuel pump 17.
[0037] In the second operating mode of the dual-fuel internal combustion engine, the relatively non-flammable liquid fuel held in the second fuel tank 19 is again fed to the first line 34 of the corresponding fuel injector 16 via the first fuel pump 17. In the second operating mode, the relatively flammable fuel originating from the fuel tank 18 is fed to the second line 35 of the corresponding fuel injector via the second fuel pump 24.
[0038] Apart from the two fuel tanks 18 and 19, Figure 1 Shuttle valve 22 is also shown. A fuel tank 18, which is prepared with relatively flammable liquid fuel, is connected to shuttle valve 22 via fuel line 20, while a second fuel tank 19, which is prepared with relatively non-flammable liquid fuel, is connected to shuttle valve 22 via fuel line 21.
[0039] Specifically, when the dual-fuel internal combustion engine 11 operates in the first operating mode, the fuel tank 16 is connected to the fuel pump 17 via the shuttle valve 22. In the first operating mode, the fuel tank 19 is disengaged from the fuel pump 17. In contrast, when the dual-fuel internal combustion engine operates in the second operating mode, the fuel tank 19, which holds relatively non-flammable liquid fuel, is connected to the first fuel pump 17 via the shuttle valve 22. In the second operating mode, the fuel tank 18, which holds relatively flammable liquid fuel, is disengaged from the first fuel pump 17 via the shuttle valve 22.
[0040] According to Figure 1Clearly, the fuel line 23 originating from the second fuel pump 24 extends along the direction of cylinder 12, and the fuel line 23 is connected to the second line 35 of the corresponding fuel injector 16. The fuel line 25 originating from the fuel pump 17 extends along the direction of cylinder 12, and the fuel line 25 is connected to the corresponding first line 34 of the corresponding fuel injector 16.
[0041] Specifically, when the dual-fuel internal combustion engine 11 operates in the first operating mode, the two lines 34 and 35 of the corresponding fuel injector 16 are connected to the fuel tank 18, so that relatively combustible liquid fuel is then fed to the two lines 34 and 35 of the corresponding fuel injector 16. Specifically, when the dual-fuel internal combustion engine 11 operates in the second operating mode, the first line 34 is connected to the fuel tank 19, and the second line 35 of the corresponding fuel injector 16 is connected to the fuel tank 18, so that in the second operating mode, relatively non-flammable liquid fuel is then fed to the needle fuel chamber 31 of the corresponding fuel injector 16 via the first line 34, and relatively combustible liquid fuel is fed to the needle fuel chamber 31 of the corresponding fuel injector 16 via the second line 35.
[0042] The pressure in the second line 35 is slightly higher than the pressure in the first line 34, such that in the second operating mode, relatively combustible fuel from the second line 35 can be introduced into a portion 31a of the needle fuel chamber 31 in a defined manner, wherein the needle fuel chamber 31, i.e., its portion 31a, is connected to the second line 35 via a choke 26. By designing the size of the choke 26, the amount of relatively combustible fuel introduced into the portion 31 in the second operating mode can be adjusted in a defined manner. This occurs specifically as follows: in the second operating mode, relatively combustible liquid fuel from the second line 35 is introduced into the portion 31a, and relatively non-combustible liquid fuel from the first line 34 is introduced into the portion 31b of the needle fuel chamber 31. During injection operation, in the second operating mode, relatively combustible fuel initially enters the combustion chamber 33, and thereafter, relatively non-combustible liquid fuel enters the combustion chamber 33, thus the relatively non-combustible liquid fuel can then be ignited in the second operating mode in a defined manner by the relatively combustible liquid fuel.
[0043] exist Figure 2In the preferred exemplary embodiment of the fuel injector 16 according to the invention shown, the second line 35 of the fuel injector 16, which is connected to a portion 31a of the needle fuel chamber 31 via a choke 26, is also connected to the needle guide 30 and to the control chamber 36 of the control valve 29 of the fuel injector 16. Therefore, in both operating modes of the dual-fuel internal combustion engine 11, the relative combustible fuel can be fed not only to the needle fuel chamber 31 via the second line 31, but also to the needle guide 30 and the control chamber 36 of the control valve 29. In the region of the needle guide 30, the relative combustible fuel acts as a barrier fluid, and in the region of the control chamber 36 of the control valve 29, the relative combustible fuel acts as a working fluid. Figure 2 The second line 35 of the corresponding fuel injector 16 is connected to the control chamber 36 of the control valve 29 via another choke 37.
[0044] As already explained, the pressure in the second line 35 is greater than the pressure in the first line 34. Therefore, a particularly advantageous barrier effect can be ensured by blocking the fluid in the region of the needle guide 30.
[0045] In a particularly preferred embodiment of the fuel injector 16, the second line 35 is correspondingly used not only to feed combustible fuel in the direction of the needle fuel chamber 31, but also in the direction of the control chamber 36 of the needle guide 30 and the control valve 29, such that the combustible fuel then acts as both the barrier fluid and the working fluid. This ensures a particularly simple construction of the internal combustion engine.
[0046] According to Figure 2 Clearly, the needle guide 30 is positioned between the needle fuel chamber 31 and the control chamber 36 of the control valve 29, that is, between a portion 31b of the needle fuel chamber 31 and the control chamber 36 of the control valve 29.
[0047] also, Figure 2 The spring chamber 38, in which the receiving spring 39 is located, is positioned between the needle guide 30 and the control chamber 36. The spring 39 presses the nozzle needle 28 into its closed position.
[0048] The relatively flammable liquid fuel is preferably a liquid fuel with a lubricating hardness (WSD) between 100 μm and 300 μm, preferably between 100 μm and 200 μm. The relatively flammable fuel is preferably diesel fuel. The relatively non-flammable liquid fuel is preferably a liquid fuel with a lubricating hardness (WSD) between 300 μm and 820 μm, preferably between 400 μm and 820 μm. The relatively non-flammable fuel is preferably ethanol or methanol.
[0049] In addition to the fuel injector 16 according to the invention, the invention also relates to a dual-fuel internal combustion engine 11, wherein each cylinder 12 of the dual-fuel internal combustion engine 11 includes at least one, preferably a single, fuel injector 16 according to the invention. Through the fuel injector 16, relatively combustible fuel can be fed to the cylinder 12 in a first operating mode, and relatively combustible fuel and relatively non-combustible fuel can be fed to the cylinder 12 in a second operating mode, wherein the relatively combustible fuel is used to ignite the relatively non-combustible fuel.
[0050] Furthermore, the present invention relates to a method for operating a dual-fuel internal combustion engine 11. In a first operating mode, relatively combustible fuel is specifically fed to cylinder 12 via a corresponding fuel injector 16, i.e., introduced into the combustion chamber 33 of the corresponding cylinder 12. In contrast, in a second operating mode, relatively combustible fuel and relatively non-combustible fuel are jointly introduced into the combustion chamber 33 of the corresponding cylinder 12 via corresponding fuel injectors 16, wherein in the second operating mode, the relatively combustible fuel is used to ignite the relatively non-combustible fuel.
[0051] Figure 3 This illustrates the possibilities regarding how relatively combustible and relatively non-combustible fuels can be introduced into the combustion chamber 33 of the respective cylinder 12 in the second operating mode. Therefore, Figure 3 The diagram illustrates the injection into cylinder 12 at time t in a second operating mode, wherein the injection begins at time t1 and ends at time t2. Due to the fact that in the second operating mode, relatively combustible fuel is collected in partial chamber 31a and relatively non-combustible fuel in partial chamber 31b, the relatively combustible fuel from the first partial chamber 31a is initially introduced into the combustion chamber 33 of the corresponding cylinder 12 between times t1 and t3. Thereafter, the relatively non-combustible fuel from partial chamber 31b is introduced into the combustion chamber 33 of the corresponding cylinder 12 between times t3 and t2. The relatively non-combustible fuel is ignited via the relatively combustible fuel.
[0052] Figure 4 An alternative procedure for injecting fuel using the fuel injector 16 according to the invention is shown, wherein in Figure 4 In this process, relatively non-flammable fuel originating only from partial chamber 31a is initially injected and ignited in the combustion chamber 33 of the corresponding cylinder 12 between times t1 and t3 to regulate combustion chamber 33. After time t3, the actual main injection begins at time t4 with a time offset Δt, where relatively flammable fuel, initially again originating from partial chamber 31a and subsequently relatively non-flammable fuel, is introduced into the combustion chamber 33 of the corresponding cylinder 12. Therefore, in Figure 4 In the process, the injection is divided into a pre-injection between time t1 and t3 and a subsequent main injection between time t4 and t2.
[0053] With the present invention, a separate ignition injector can be omitted. Liquid fuel can be introduced into the combustion chamber 33 of the corresponding cylinder 12 in both operating modes of the dual-fuel internal combustion engine 11 through the same fuel injector 16.
[0054] In the second operating mode, the relatively combustible fuel used to ignite the relatively non-combustible fuel is stored in a portion of chamber 31a of the needle fuel chamber 31 formed adjacent to the opening 33 or the nozzle needle 38. Therefore, in the second operating mode, in each injection cycle, the relatively combustible fuel initially enters the combustion chamber 33 of the corresponding cylinder 12, so that the relatively non-combustible fuel can then be properly ignited and burned via the relatively combustible fuel. Furthermore, preferably, the relatively combustible fuel acts as both a barrier fluid and a working fluid, i.e., as a barrier fluid in the region of the needle guide 30 and as a working fluid in the region of the control valve 29.
[0055] This particularly relates to the field of so-called large engines or large internal combustion engines whose cylinders have piston diameters of at least 140 mm, and especially 175 mm. Such large internal combustion engines are, for example, marine engines. In this invention, these are embodied as dual-fuel internal combustion engines.
[0056] List of reference numerals in the attached diagram:
[0057] 10. Ship propulsion system
[0058] 11 Dual-fuel internal combustion engine
[0059] 12 cylinders
[0060] 13 Generators
[0061] 14. Ship propellers
[0062] 15. Fuel Supply System
[0063] 16 Fuel Injectors
[0064] 17. Fuel Pump
[0065] 18 fuel tanks
[0066] 19 Fuel Tanks
[0067] 20 Fuel Pipelines
[0068] 21 Fuel Line
[0069] 22 Shuttle Valve
[0070] 23 Fuel lines
[0071] 24 Fuel Pumps
[0072] 25 Fuel lines
[0073] 26. Air choke
[0074] 27 Main Body
[0075] 28 Nozzle needles
[0076] 29 Control valve
[0077] 30-pin guide
[0078] 31 needle fuel chamber
[0079] 31a Partial Room
[0080] 31b Partial Room
[0081] 32 Opening
[0082] 33 Combustion Chamber
[0083] 34 pipelines
[0084] 35 pipelines
[0085] 36 Control Room
[0086] 37. Air choke
[0087] 38 Spring chambers
[0088] 39 Springs
[0089] 40. Contraction section.
Claims
1. A fuel injector (16) for a dual-fuel internal combustion engine (11), said fuel injector (16) being designed to feed fuel to the combustion chamber (33) of a cylinder (12) of said dual-fuel internal combustion engine (11), The fuel injector (16) has a body (27), The fuel injector (16) has a nozzle needle (28) movably guided in the needle guide (30) of the body (27). The fuel injector (16) has a needle fuel chamber (31) defined by the body (27), the needle fuel chamber (31) being connectable via an opening (32) to the combustion chamber (33) of the cylinder (12), wherein the opening (32) is open in a first position of the nozzle needle (28) and closed in a second position of the nozzle needle (28). A first line (34) connected to the needle fuel chamber (31) is introduced into the body (27), wherein a first liquid fuel is introduced into the needle fuel chamber (31) via the first line (34). A second pipeline (35), separate from the first pipeline (34), is introduced into the body (27). The second pipeline (35) is connected to the needle fuel chamber (31), wherein a second liquid fuel can be introduced into the needle fuel chamber (31) via the second pipeline (35). The needle fuel chamber (31) comprises a first chamber (31b) and a second chamber (31a). The second chamber (31a) is formed adjacent to the opening (32). The second pipeline (35) is connected to and leads to the second sub-chamber (31a) via a control element. The first pipeline (34) leads to a first portion chamber (31b) of the needle fuel chamber (31), the first portion chamber (31b) being spaced apart from the opening (32), and The first chamber (31b) and the second chamber (31a) of the needle fuel chamber (31) are connected to each other via a choke-like contraction section (40).
2. The fuel injector according to claim 1, wherein the control element is a choke (26).
3. The fuel injector according to claim 1 or 2, wherein the second line (35) is also connected to the needle guide (30) of the fuel injector (16), wherein the second liquid fuel can be fed to the needle guide (30) via the second line (35) as a barrier fluid.
4. The fuel injector according to claim 1 or 2, wherein the second line (35) is also connected to the control chamber (36) of the control valve (29) of the fuel injector (16), wherein the second liquid fuel can be fed to the control chamber (36) via the second line (35) as a working fluid.
5. The fuel injector according to claim 4, wherein the second line (35) is connected to the control chamber (36) of the control valve (29) via a choke (37).
6. The fuel injector according to claim 4, wherein the needle guide (30) is positioned between the needle fuel chamber (31) and the control chamber (36) of the control valve (29).
7. The fuel injector according to claim 1 or 2, The fuel injector mentioned above is a dual-fuel injector. In the first operating mode of the dual-fuel internal combustion engine, both combustible fuels can be fed to the first pipeline (34) as the first liquid fuel and to the second pipeline (35) as the second liquid fuel. In the second operating mode of the dual-fuel internal combustion engine, a relatively non-flammable fuel as a first liquid fuel can be fed to the first pipeline (34), and a relatively flammable fuel as a second liquid fuel is fed to the second pipeline (35) to ignite the relatively non-flammable fuel.
8. A dual-fuel internal combustion engine (11), The internal combustion engine (11) has a cylinder (12) in which relatively combustible liquid fuel in a first operating mode and relatively non-combustible liquid fuel in a second operating mode can be burned. The internal combustion engine (11) has an injection system comprising at least one fuel injector (16) for each cylinder (12), wherein in a first operating mode, the relatively combustible liquid fuels, which are first and second liquid fuels, are both fed to the cylinder (12) via the fuel injector (16), and in a second operating mode, the relatively non-combustible liquid fuel, which is the first liquid fuel, and the relatively combustible liquid fuel, which is the second liquid fuel, for igniting the relatively non-combustible liquid fuel, are fed to the cylinder (12) via the fuel injector (16), wherein the respective fuel injector (16) is formed according to any one of claims 1 to 7.
9. A method for operating the dual-fuel internal combustion engine (11) according to claim 8, In the first operating mode, the combustible fuel is introduced into the combustion chamber (33) of the corresponding cylinder via the corresponding fuel injector (16). In the second operating mode, the relatively combustible fuel and the relatively non-combustible fuel are introduced into the combustion chamber (33) of the corresponding cylinder via the corresponding fuel injector (16). In the second operating mode, the relatively combustible fuel is used to ignite the relatively non-combustible fuel.