Fuel injector for dual-fuel internal combustion engine and dual-fuel internal combustion engine

Abstract

The invention relates to a fuel injector for a dual-fuel internal combustion engine and a dual-fuel internal combustion engine. A fuel injector for a dual-fuel internal combustion engine, which is designed to supply fuel to a combustion chamber of a cylinder of the dual-fuel internal combustion engine, has a body, a nozzle needle movably guided in a needle guide of the body, a needle fuel chamber defined by the body and connectable to the combustion chamber of the cylinder via an orifice, wherein the orifice is open in a first position of the nozzle needle and closed in a second position of the nozzle needle, wherein a first line connected to the needle fuel chamber is introduced into the body, wherein fuel can be introduced into the needle fuel chamber via the first line, and wherein a second line separated from the first line is introduced into the body, the second line being connected to the needle guide on the one hand and to a control chamber of a control valve of the fuel injector on the other hand, wherein fuel can be supplied to the needle guide as a barrier fluid and to the control chamber as a working fluid via the second line.

Description

Technical Field

[0001] The present invention relates to a fuel injector for a dual-fuel internal combustion engine. Furthermore, the present invention relates to a dual-fuel internal combustion engine.

[0002] The invention proposed here relates 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. Background Art

[0003] Dual fuel internal combustion engines are known as marine engines. Dual fuel internal combustion engines known from practice can be operated in a first operating mode in which the dual fuel internal combustion engine combusts a liquid fuel and in a second operating mode in which the dual fuel internal combustion engine combusts a gaseous fuel or another liquid fuel.

[0004] A dual-fuel internal combustion engine with dual fuel injectors is known from DE 10 2017 123 315 A1. Each fuel is delivered in the direction of the dual fuel injectors via a separate fuel pump. In addition, there are separate seals and lubricating oil systems. Summary of the invention

[0005] Starting from this point, the invention is based on the object 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 object is achieved by a fuel injector according to claim 1 .

[0007] The fuel injector is designed to supply liquid fuel to a combustion chamber of a cylinder of a dual-fuel internal combustion engine. The fuel injector comprises a body, a nozzle needle which is movably guided in a needle guide of the body, and a needle fuel chamber defined by the body, the needle fuel chamber being connectable to the combustion chamber via an orifice, wherein the orifice is open in a first position of the nozzle needle and closed in a second position of the nozzle needle.

[0008] A first line coupled to a needle fuel chamber is introduced in the body of the fuel injector, wherein liquid fuel can be introduced into the needle fuel chamber via the first line.

[0009] Furthermore, a second line, separate from the first line, is introduced into the body of the fuel injector, the second line being connected on the one hand to the needle guide and on the other hand to a control chamber of a control valve of the fuel injector, wherein liquid fuel can be supplied to the needle guide as barrier fluid and to the control chamber as working fluid via the second line.

[0010] The fuel injector according to the invention allows particularly advantageous injection of fuel into the combustion chamber of the respective cylinder of a dual-fuel internal combustion engine that combusts a liquid fuel. In an operating mode of the dual-fuel internal combustion engine, the fuel can be injected into the combustion chamber of the respective cylinder via the fuel injector, wherein in this operating mode, preferably, another fuel that is introduced into the respective combustion chamber of the respective cylinder in another operating mode acts as a barrier fluid and working fluid. This allows a particularly simple construction of the fuel injector.

[0011] According to a further development, the fuel injector is a dual fuel injector, wherein in a first operating mode of the dual fuel internal combustion engine, a relatively combustible fuel can be supplied to the first line and the second line respectively, and wherein in a second operating mode of the dual fuel internal combustion engine, the first fuel can be supplied to the second line and the relatively hardly combustible second fuel can be supplied to the first line. Such a dual fuel injector is particularly preferred and allows a particularly simple construction of the dual fuel internal combustion engine.

[0012] According to a further development of the present invention, the second pipeline is connected to the control chamber of the control valve via a throttle portion. This is preferred in order to supply the corresponding fuel to the control chamber of the control valve.

[0013] The dual-fuel internal combustion engine according to the invention is defined in claim 6 . BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Preferred further developments of the invention are obtained from the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail by means of the drawings, without being restricted to the drawings. The drawings show:

[0015] Figure 1 : Diagram of a ship propulsion system with a dual fuel internal combustion engine;

[0016] Figure 2 : A selection from a dual-fuel internal combustion engine in the region of the cylinder;

[0017] Figure 3 : Cross section through a fuel injector of a dual-fuel internal combustion engine. DETAILED DESCRIPTION

[0018] Figure 1 A marine propulsion system 10 is shown in a highly schematic manner and comprises a dual-fuel internal combustion engine 11 having a plurality of cylinders 12 .

[0019] In the cylinder 12, fuel is combusted, i.e., in a first operating mode of the dual-fuel internal combustion engine 11, a first liquid fuel is combusted, and in a second operating mode of the dual-fuel internal combustion engine 11, a second liquid fuel is combusted. During the combustion of the respective fuels, the dual-fuel internal combustion engine 11 generates a driving power which is Figure 1 The electric power is utilized in order to drive the generator 13. In the generator 13, electric energy for driving the propeller 14 of the ship is generated.

[0020] also, Figure 1 A fuel supply system 15 of a dual-fuel internal combustion engine 11 is shown. Figure 2 , Figure 3 Further components of the fuel supply system 15 are shown. By means of the fuel supply system 15, a corresponding liquid fuel can be supplied to the cylinders 12 of the dual-fuel internal combustion engine 11 in a corresponding operating mode of the dual-fuel internal combustion engine 11. The fuel supply system 15 of the dual-fuel internal combustion engine 11 comprises a main injection system and a pilot injection system.

[0021] The main injection system (which includes at least one main injector 16 for each cylinder 12 (see Figure 2 , Figure 3 )), a relatively combustible first liquid fuel can be supplied to the cylinder 12 in the first operating mode and a relatively barely combustible second liquid fuel can be supplied to the cylinder 12 in the second operating mode. By means of this main injector 16, the first liquid fuel can be injected into the respective cylinder 12 in the first operating mode and the second liquid fuel can be injected into the cylinder 12 in the second operating mode. Although it is preferred for cost reasons to inject the first liquid fuel into the respective cylinder 12 of the dual-fuel internal combustion engine in the first operating mode and the second liquid fuel into the respective cylinder 12 in the second operating mode via the same main injector 16, it is alternatively also possible for each cylinder 12 to have a separate main injector for each of the two liquid fuels.

[0022] The illustrated embodiment is preferred in which the same main injector 16 is used for injecting a first liquid fuel into the cylinders in the first operating mode and for injecting a second liquid fuel into the cylinders in the second operating mode.

[0023] according to Figure 2 , the respective liquid fuel can be supplied to the respective main injector 16 via the main pump 17 , which thus delivers the first liquid fuel in the first operating mode and the second liquid fuel in the second operating mode in the direction of the respective main injector 16 .

[0024] Figure 1A first fuel tank 18 for holding a first liquid fuel and a second fuel tank 19 for holding a second liquid fuel are shown. The first fuel tank 18 may be coupled to the main pump 17 via a first fuel line 20, and the second fuel tank 19 may be coupled to the main pump 17 via a second fuel line 21, i.e., the first fuel tank 18 and the second fuel tank 19 are coupled to the main pump 17 by means of a shuttle valve 22.

[0025] In the first operating mode, the shuttle valve 22 couples the first fuel tank 18 or the first fuel line 20 to the main pump 17 of the main injection system in order to supply 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 decouples the second fuel tank 19 from the main pump 17 of the main injection system.

[0026] In the second operating mode, by contrast, the shuttle valve 22 assumes a switching position in which the second fuel tank 19 is coupled to the main pump 17 of the main injection system via the second fuel line 21 in order to supply the second fuel to the cylinders 12 of the dual-fuel internal combustion engine 11 in the second operating mode. In this second operating mode, the first fuel tank 18 is then disconnected from the main pump 17 of the main injection system.

[0027] As already explained, the first liquid fuel is relatively flammable and the second liquid fuel is relatively barely flammable. In order to ignite the second liquid fuel in the second operating mode in the region of the respective cylinder 12, the dual-fuel internal combustion engine comprises a pilot injection system comprising at least one pilot injector 23 for each cylinder 12.

[0028] By means of the pilot injection system, a first liquid fuel for igniting a second liquid fuel can be supplied to the cylinders 12 of the internal combustion engine in the second operating mode. Therefore, in addition to at least one pilot injector 23 for each cylinder 12, the pilot injection system also comprises a pilot pump 24, via which in the second operating mode the respective pilot injector 23 can be supplied with the first liquid fuel originating from the first fuel tank 18. A further fuel line 40 extends from the first fuel tank 18 in the direction of the cylinders 12, wherein the pilot pump 24 is connected to the further fuel line 40.

[0029] As from Figure 2 It is obvious that in the case of a dual-fuel internal combustion engine 11, the main injection system and the pilot injection system are coupled, i.e., coupled in such a way that in the second operating mode, the first liquid fuel originating from the pilot injection system (which comprises a pilot pump 24 and at least one pilot injector 23 for each cylinder 12) can be supplied to the corresponding main injector 16 of the main injection system, wherein the first liquid fuel acts as a working fluid and as a barrier fluid in the region of the corresponding main injector 16 in the second operating mode. Thus, Figure 2 A branch line 25 is shown, which branches off from the pilot injection system upstream of the respective pilot injector 23 and leads to the respective main injector 16 of the main injection system of the respective cylinder 12 and opens into the main injection system in the region of the respective main injector 16. Viewed in the delivery direction of the pilot injection system, the branch line 25 branches off from the pilot injection system downstream of the pilot pump 24 and upstream of the respective pilot injector 23 in order to supply the first liquid fuel as working fluid and barrier fluid to the respective main injector 16 of the main injection system in the second operating mode.

[0030] In the second operating mode, in the respective branch line 25 leading from the pilot injection system to the main injection system, there is a pressure which is greater (preferably greater by a defined pressure deviation) than the pressure in the region of the respective main injector 16. In this way, in the second operating mode it is ensured that the first liquid fuel can always be reliably supplied to the respective main injector 16.

[0031] exist Figure 2 In the embodiment, a pressure reducer 26 is integrated in the branch line 25 shown there. The pressure reducer 26 limits the pressure in the corresponding branch line 25 located downstream of the pressure reducer 26 to a defined level.

[0032] The relatively flammable first liquid fuel is preferably a liquid fuel having a lubricity WSD between 100 μm and 300 μm, preferably between 100 μm and 200 μm. The relatively nearly non-flammable second liquid fuel is preferably a liquid fuel having a lubricity WSD between 300 μm and 820 μm, preferably between 400 μm and 820 μm. The first liquid fuel is preferably diesel fuel. The second liquid fuel is preferably ethanol or methanol.

[0033] In the dual-fuel internal combustion engine 11, which in each of the two operating modes combusts a liquid fuel, the first liquid fuel is used in the second operating mode on the one hand to ignite the second liquid fuel, and on the other hand to act as a working fluid and a barrier fluid in the region of the corresponding main injector 16. Therefore, in the second operating mode, the main injector 16 and the pilot injector 23 of the corresponding cylinder 12 utilize the first liquid fuel as an ignition fluid introduced into the corresponding cylinder 12 via the corresponding pilot injector 23 on the one hand, and utilize the first liquid fuel as a working fluid and a barrier fluid in the region of the main injector 16 of the corresponding cylinder 12 on the other hand.

[0034] Figure 3 A schematic cross section through a main injector 16 of a dual-fuel internal combustion engine 11 designed in accordance with the invention presented here is shown.

[0035] The fuel injector 16 comprises a preferably multi-part body 27 , a nozzle needle 28 and a control valve 29 .

[0036] The nozzle needle 28 is movably guided in a needle guide 30 of the body 27. The body 27 defines a needle fuel chamber 31. The needle fuel chamber 31 can be coupled to a combustion chamber 33 of the respective cylinder 12 via an orifice 32. In the first position of the nozzle needle 28, the nozzle needle 28 closes the orifice 32, while in the second position of the nozzle needle 28, the nozzle needle 28 opens the orifice 32.

[0037] A first line 34 is introduced in the body 27 . Fuel can be supplied to the needle fuel chamber 31 via this first line 34 .

[0038] In the exemplary embodiment shown, which in the case of a main injector 16 is a dual-fuel injector of a dual-fuel internal combustion engine 11, a relatively combustible first fuel originating from a first fuel tank 18 can be supplied via a first line 34 to a needle fuel chamber 31 of the main injector 16 via the main pump 17 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 barely combustible fuel originating from a second fuel tank 19 can be supplied via the first line 34 to the needle fuel chamber 31 of the main injector 16 via the main pump 17. As explained above, in this regard, the shuttle valve 22 assumes a corresponding switching position.

[0039] In addition to the first line 34, a second line 35, which is separate from the first line 34, also leads into the body 27. By means of this second line 35, the first fuel can be supplied to the needle guide 30 on the one hand and to the control chamber 36 of the control valve 29 of the main injector 16 on the other hand (i.e. in the second operating mode of the dual-fuel internal combustion engine 11). The first fuel originating from the pilot injection system can be supplied via Figure 2 23, which branches from the first fuel downstream of the pilot pump 24 and upstream of the pilot injector 23. The first fuel supplied to the needle guide 30 via the second line 35 acts as a barrier fluid there. The first fuel supplied to the control chamber 36 of the control valve 29 via the first line 35 acts as a working fluid there. The fuel acting as a working fluid can be supplied to the control chamber 36 via a throttle 37 guided to the control chamber 36.

[0040] As already mentioned above Figure 2 As explained, the pressure in the branch line 25 and thus in the second line 35 is greater than the pressure in the first line 34. Thus, a particularly advantageous barrier effect can be provided via the barrier fluid in the region of the needle guide 30.

[0041] Thus, the fuel guided via the second line 35 in the fuel injector according to the invention acts as a barrier fluid on the one hand and as a working fluid on the other hand. This makes possible a particularly simple construction of the fuel injector 16 and of the dual-fuel internal combustion engine 11 comprising the fuel injector 16. In the second operating mode, in which the second fuel is combusted in the cylinder 12, a simple separation between the combusted second fuel and the first fuel acting as barrier fluid and working fluid is possible.

[0042] according to Figure 3 The needle guide 30 is positioned between the needle fuel chamber 31 and the control chamber 36 of the control valve 29 .

[0043] Positioned between the needle guide 30 and the control chamber 36 is a spring chamber 38 in which a spring 39 is accommodated, which presses the nozzle needle 28 into the second position.

[0044] This 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 present invention, these engines are embodied as dual-fuel internal combustion engines.

[0045] Reference List

[0046] 10 Ship propulsion system

[0047] 11 Dual-fuel internal combustion engine

[0048] 12 Cylinders

[0049] 13. Generator

[0050] 14 Ship propulsion

[0051] 15 Fuel Supply System

[0052] 16 Main injector

[0053] 17 Main pump

[0054] 18 Fuel Tank

[0055] 19 Fuel Tank

[0056] 20 Fuel lines

[0057] 21 Fuel lines

[0058] 22 Shuttle valve

[0059] 23 Pilot injector

[0060] 24 Pilot pump

[0061] 25 Branch pipeline

[0062] 26 Pressure reducer

[0063] 27 Main Body

[0064] 28 Nozzle needle

[0065] 29 Control valve

[0066] 30 Needle guide

[0067] 31 Needle Fuel Chamber

[0068] 32 Orifice

[0069] 33 Combustion Chamber

[0070] 34 pipeline

[0071] 35 pipeline

[0072] 36 Control Room

[0073] 37 Throttling

[0074] 38 Spring Chamber

[0075] 39 Spring

[0076] 40 Fuel lines.

Claims

1. A fuel injector (16) of a dual-fuel internal combustion engine (11), designed to supply fuel to a combustion chamber (33) of a cylinder (12) of the dual-fuel internal combustion engine (11), having a body (27), A nozzle needle (28) is provided, which is movably guided in a needle guide (30) of the body (27), A needle fuel chamber (31) is defined by the body (27), the needle fuel chamber (31) being connectable to the combustion chamber (33) of the cylinder (12) via an orifice (32), wherein: The opening (32) is open in a first position of the nozzle needle (28) and is closed in a second position of the nozzle needle (28), wherein a first pipeline (34) connected to the needle fuel chamber (31) is introduced into the body (27), wherein fuel can be introduced into the needle fuel chamber (31) via the first pipeline (34), wherein a second line (35) is introduced into the body (27) and is separate from the first line (34), the second line (35) being connected on the one hand to the needle guide (30) and on the other hand to a control chamber (36) of a control valve (29) of the fuel injector (16), wherein 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), wherein the fuel injector is a dual fuel injector, wherein, in a first operating mode of the dual-fuel internal combustion engine, a relatively combustible first fuel can be supplied to the first line (34) and the second line (35), respectively, Therein, in a second operating mode of the dual-fuel internal combustion engine, the first fuel can be supplied to the second line (35) and a relatively hardly combustible second fuel can be supplied to the first line (34).

2. The fuel injector according to claim 1, in, The second pipeline (35) is connected to the control chamber (36) of the control valve (29) via a throttle (37).

3. The fuel injector according to any one of claims 1 to 2, in, The needle guide (30) is positioned between the needle fuel chamber (31) and the control chamber (36) of the control valve (29).

4. The fuel injector according to claim 3, in, A spring chamber (38) is positioned between the needle guide (30) and the control chamber (36), and a spring (39) that presses the nozzle needle (28) into the second position is accommodated in the spring chamber (38).

5. A dual-fuel internal combustion engine (11), A cylinder (12) is provided in which a first fuel can be combusted in a first operating mode and a second fuel can be combusted in a second operating mode, A main injection system is provided, comprising at least one main injector (16) for each cylinder (12), the first fuel being deliverable to the cylinder (12) via the at least one main injector (16) in the first operating mode, and the second fuel being deliverable to the cylinder (12) via the at least one main injector (16) in the second operating mode, wherein: The main injector (16) is designed according to any one of claims 1 to 4. A pilot injection system is provided, which comprises at least one pilot injector (23) for each cylinder (12), wherein the first fuel for igniting the second fuel can be supplied to the cylinder (12) of the internal combustion engine via the at least one pilot injector (23) in the second operating mode.

6. The dual-fuel internal combustion engine (11) according to claim 5, in, The main injection system and the pilot injection system are coupled in such a way that in the second operating mode the first fuel originating from the pilot injection system can be supplied to the respective main injector (16) as working fluid and as barrier fluid.

7. A dual fuel internal combustion engine (11) according to claim 5 or 6, in, Upstream of the respective pilot injector (23), the respective branch line (25) branches off from the pilot injection system and opens into the second line (35) of the respective main injector (16).

8. The dual-fuel internal combustion engine (11) according to claim 7, in, A pressure reducer (26) is integrated into the respective branch line (25) in order to limit the pressure in the respective branch line (25).

9. A dual fuel internal combustion engine (11) according to any one of claims 5 to 6, in, The main injection system comprises a main pump (17), the first fuel being supplyable to the cylinder (12) via the main pump (17) in the first operating mode, and the second fuel being supplyable to the cylinder (12) via the main pump (17) in the second operating mode, wherein the pilot injection system comprises a pilot pump (24), and the first fuel for igniting the second fuel can be supplied to the cylinder (12) via the pilot pump (24) in the second operating mode, wherein a shuttle valve (22) couples the main pump (17) to a first fuel tank (18) for the first fuel in the first operating mode and couples the main pump (17) to a second fuel tank (18) for the second fuel in the second operating mode.

Images