Fuel injection valve

Abstract

The invention relates to a fuel injection valve (10.1), comprising: a housing which has a control fluid inlet, a fuel inlet and a nozzle body having an injection valve seat; a high-pressure control chamber (32) which is arranged in the housing and is connected to the control fluid inlet; a fuel chamber (22) which is arranged in the housing and extends from the fuel inlet to the injection valve seat; a control piston (51) which is arranged in the housing in a displaceable manner along a longitudinal axis (L) and to a which a closing force directed towards the injection valve seat can be applied by a control pressure spring; a hydraulic control device for controlling the displacement of the control piston along the longitudinal axis; a nozzle needle which is arranged at an end of the control piston facing the injection valve seat and which is designed to interact with the injection valve seat in order to inject fuel into the combustion chamber of the internal combustion engine, wherein the nozzle needle can be moved by displacement of the control piston along the longitudinal axis.

Description

[0001] FUEL INJECTOR

[0002] Field of the invention

[0003] The present invention relates to a fuel injection valve for intermittent injection of fuel into the combustion chamber of an internal combustion engine.

[0004] Background of the invention

[0005] Fuel injectors are used to inject fuel into the combustion chamber of an internal combustion engine, particularly diesel engines. In recent years, various gaseous or liquid fuels such as hydrogen, methane, methanol, ammonia, etc., have been proposed alongside conventional diesel, particularly as green and low-emission alternatives.

[0006] Due to the multitude of possible fuels, it can be advantageous to adapt the fuel injectors to the possible variants. One possibility is to provide multi-fuel-capable injectors that can use multiple fuels. One such option is dual-fuel systems, which can use, for example, a liquid fuel such as diesel or marine diesel oil, or a gaseous fuel such as hydrogen, methane, or biogas.

[0007] WO 2015 / 101406 A1 describes such a dual-fuel injection system, which has a first nozzle needle with an axially controllable stroke for dispensing liquid fuel via a first nozzle arrangement of the dual-fuel fuel injector. The first nozzle needle is preferably accommodated in a nozzle body of the fuel injector. The dual-fuel fuel injector furthermore has a plurality of second nozzle needles with an axially controllable stroke arranged around the first nozzle needle for dispensing gaseous fuel via a second nozzle arrangement of the dual-fuel fuel injector, for example two, three, four, five or more second nozzle needles. In particular, an arrangement is provided with a central first nozzle needle and second nozzle needles arranged off-center therefrom, preferably concentrically to the first nozzle needle. Like the first nozzle needle, the second nozzle needles are preferably also accommodated in the nozzle body.Within the framework of the second nozzle arrangement, each of the second nozzle needles is assigned, for example, one or more gas injection nozzle openings on the injector that can be released via the same.

[0008] Description of the invention

[0009] The known multi-fuel capable injection systems, such as the dual-fuel injection system described at the beginning, in which several nozzle needles are used, result in a correspondingly greater space requirement and complexity. The fact that several separate circuits are present for the first and second nozzle needles, even if only a specific fuel is required in a particular application, also contributes to the greater space requirement. In addition, these systems are comparatively invariable, since the number and structure of the nozzle needles and nozzle bodies are fixed and unchangeable. This can be particularly disadvantageous because it is often not known in advance which fuel is required in a specific application. Since injectors according to, for example, WO 2015 / 101406 A1, have a complex structure, they are relatively expensive to manufacture and maintain.Furthermore, reliability over long periods of operation can be compromised by the complex design. Since internal combustion engines with such injection systems are used in areas such as mining, marine, or other heavy-duty applications, an injector failure leading to engine failure can quickly generate high costs. Reliability and longevity of the injectors are therefore particularly desirable.

[0010] In this regard, it may therefore be desirable to provide a fuel injector which is advantageously of simpler construction and has increased adaptability with respect to different fuels while providing reliable controllability of the injection processes.

[0011] It is therefore an object of the present invention to provide a fuel injection valve which at least partially improves the prior art.

[0012] This object is achieved with a fuel injection valve having the features of the independent claim. Advantageous embodiments of the invention are given in the dependent claims and in the present description and the figures. The invention relates to a fuel injection valve for the intermittent injection of fuel into a combustion chamber of an internal combustion engine, comprising a housing extending along a longitudinal axis, which has a control fluid inlet, a fuel inlet and a nozzle body with an injection valve seat, a high-pressure control chamber arranged in the housing, which is connected to the control fluid inlet, a fuel chamber arranged in the housing, which runs from the fuel inlet to the injection valve seat, a control piston arranged in the housing so as to be adjustable along the longitudinal axis,which is subjected to a closing force directed in the direction of the injection valve seat by a control pressure spring, a hydraulic control device for controlling the adjustment of the control piston along the longitudinal axis, a nozzle needle arranged at an end of the control piston facing the injection valve seat, which nozzle needle is arranged at least partially in the nozzle body and is designed to cooperate with the injection valve seat for injecting fuel into the combustion chamber of the internal combustion engine, wherein the nozzle needle is movable by adjusting the control piston along the longitudinal axis.

[0013] Compared to known solutions in which the position of the nozzle needle is controlled by adjusting a control section of the nozzle needle, more precise control can be achieved by providing the control piston and the control fluid separately in the high-pressure control chamber, which can be designed, in particular, independently of the properties of the respective fuel used. The nozzle needle, the injection valve seat, and / or the at least one injection opening can, in turn, be adapted to the requirements of the fuel in the fuel chamber.

[0014] In the present fuel injector, the control components and the injection components can therefore be structurally decoupled from one another, at least in essential parts. This improves the adaptability of the fuel injector to the requirements of the control system or the fuel, both for the control components such as the control piston and / or the control fluid in the high-pressure control chamber, and for the injection components such as the nozzle needle, the injection valve seat, the at least one injection opening, and / or the fuel chamber.

[0015] For example, due to the separation of the control components and the injection components, the fuel injector can be operated with a gaseous fuel and with a liquid control fluid for hydraulic control. However, it is also possible to use the fuel injector with a liquid fuel by exchanging the injection components.

[0016] The separate design of the control piston and the nozzle needle offers the further advantage that separate, independent guides can be provided for the control piston and the nozzle needle. Since the control piston and the nozzle needle are designed as separate components, a slight misalignment of the control piston and injection needle can play a subordinate or negligible role when assembling the injector. The control piston and the nozzle needle can each be guided by their assigned guide, without a slight misalignment causing disruptive friction in the respective guides. This ensures smooth and low-friction operation.

[0017] To move the nozzle needle, an end face of the control piston facing the injection valve seat preferably interacts with an end face of the nozzle needle facing away from the injection valve seat. In one variant, the end face of the control piston facing the injection valve seat is larger than the end face of the nozzle needle facing away from the injection valve seat. In an alternative variant, the end face of the control piston facing the injection valve seat is smaller than the end face of the nozzle needle facing away from the injection valve seat. In a further alternative variant, the end face of the control piston facing the injection valve seat is the same size as the end face of the nozzle needle facing away from the injection valve seat.

[0018] Preferably, the high-pressure control chamber and the fuel chamber are fluidically separated.

[0019] The fluidic separation of the high-pressure control chamber and the fuel chamber allows for the provision of separate fluidic circuits for the control fluid and the fuel. This improves the decoupling of the control components and the injection components. In this context, those skilled in the art will understand that the fluidic separation can be achieved with the smallest possible (tolerable) leakage from the high-pressure control chamber into the fuel chamber.

[0020] In one embodiment, the fuel injection valve has an intermediate body in which the control piston and the high-pressure control chamber are at least partially arranged, wherein the nozzle body is adjacent to a downstream end face of the intermediate body.

[0021] The intermediate body can accommodate the control piston in such a way that the end of the piston facing the injection valve seat can interact with the nozzle needle.

[0022] In one embodiment, the intermediate body has a transverse wall that axially delimits the high-pressure control chamber relative to the nozzle body. The transverse wall of the intermediate body can provide a spatial separation between the high-pressure control chamber and the fuel chamber.

[0023] In one embodiment, the nozzle body or the intermediate body has a guide bore in which an adjusting section of the control piston, which is arranged at its end facing the injection valve seat and / or in which an adjusting section of the nozzle needle, which is arranged at its end facing away from the injection valve seat, is / are guided in a sliding fit.

[0024] The sliding fit in the guide bore can provide fluidic separation between the high-pressure control chamber and the fuel chamber. Furthermore, the guide bore can provide a receptacle or passage for the actuating section of the control piston and / or the nozzle needle so that they can meet one another or interact. In one variant, for example, the actuating section of the control piston can be guided in the guide bore in such a way that the control piston projects through the guide bore into the nozzle body and there meets the nozzle needle. In a further variant, the actuating section of the nozzle needle can be guided in the guide bore in such a way that the nozzle needle projects through the guide bore into the intermediate body and there meets the control piston.In a further variant, both the actuating section of the control piston and the actuating section of the nozzle needle can protrude into the guide bore in such a way that the control piston and the nozzle needle meet one another in the guide bore directly or indirectly, e.g. via an actuating chamber.

[0025] In one embodiment, the guide bore has a circumferential annular space, and the fuel injection valve has a leakage outlet and a leakage discharge which runs from the annular space to the leakage outlet.

[0026] Control fluid originating from a leak in the pilot bore can be collected in the annular space and discharged through the leakage drain to the leakage outlet. This minimizes or reduces the leakage of control fluid from the high-pressure control chamber into the fuel chamber through the pilot bore.

[0027] In one embodiment, the leakage discharge has a check valve which is designed to open at an opening pressure lying between the control fluid inlet pressure and the fuel chamber pressure, wherein the opening pressure is preferably closer to the fuel chamber pressure than to the control fluid inlet pressure.

[0028] In one embodiment, the opening pressure is less than 10% or approximately 10% higher than the fuel chamber pressure.

[0029] Preferably, the leakage drain primarily or exclusively drains control fluid. Preferably, the leakage drain, in particular, does not drain fuel.

[0030] With the check valve, which is set to the appropriate opening pressure, it is possible to ensure that the leakage drain is activated when it is needed to drain a leak. With a leakage drain and a check valve, sealing oil can also be dispensed with.

[0031] In an internal combustion engine with multiple cylinders, check valves can be arranged individually in / on each fuel injector. In one variant, a common check valve can be arranged in / on a collective leakage collector, which collects leakage from multiple fuel injectors.

[0032] The check valve can be arranged inside or outside the housing of the fuel injection valve.

[0033] The check valve can be designed as a mechanically spring-loaded valve with a specific, set or adjustable opening pressure. Alternatively, the check valve can be designed as an electromagnetically controlled valve with an electrically or electronically adjustable opening pressure. The electrically or electronically adjustable opening pressure can be flexibly set to an optimum opening pressure required depending on the operating state of the internal combustion engine. For example, the opening pressure can be changed if the control fluid inlet pressure is varied depending on the load and speed for better control of the fuel injection of the internal combustion engine. An injection pressure spring is preferably arranged in the nozzle body and presses the nozzle needle onto the control piston.

[0034] The injection pressure spring can ensure that the nozzle needle follows the movement of the control piston, particularly when the control piston is moved away from the injection valve seat in order to open the fuel injection valve. The injection pressure spring is preferably designed such that the nozzle needle is in contact with the end face of the control piston thanks to the injection pressure spring. The injection pressure spring can be particularly advantageous with a gaseous fuel and a liquid control fluid, since in such a case the pressure in the fuel chamber is generally much lower than in the high-pressure control chamber.

[0035] In one embodiment, a fluidically sealed actuating chamber is arranged between the control piston and the nozzle needle, which is delimited radially by the nozzle body or by the intermediate body and axially by the control piston and the nozzle needle.

[0036] In this context, the expert understands that the control space should be fluidically sealed except for small (tolerable) leakage.

[0037] The adjustment chamber can be particularly advantageous in the case of a liquid fuel, since in such a case there is usually a sufficiently high pressure in the fuel chamber and the nozzle needle can be adjusted by axial movement of the control piston and via the adjustment chamber.

[0038] In one embodiment, the fuel injection valve has an actuator receiving body to which the nozzle body is releasably fastened, preferably with a union nut, such that the nozzle body and the nozzle needle are interchangeable.

[0039] The interchangeability of the nozzle body and nozzle needle offers the advantage that the fuel injector can be easily adapted to different fuels. The control components can remain unchanged, as these, and in particular the control circuit, are decoupled from the injection components and the fuel circuit, simplifying adaptability. Depending on the fuel, injection components adapted to the fuel, such as nozzle bodies with adapted injection valve seats and / or injection openings and / or nozzle needles, can be used.

[0040] The fuel injection valve can therefore be easily adapted for different applications.

[0041] In one embodiment, both the intermediate body and the nozzle body are releasably secured to the actuator receiving body by a union nut. The union nut allows the nozzle body to be pressed against the intermediate body and the intermediate body to be pressed against the actuator receiving body in a known manner.

[0042] In one embodiment, the nozzle body is releasably attached to the intermediate body with a union nut.

[0043] In one embodiment, the nozzle needle is guided in a needle guide section of the nozzle body, wherein the nozzle needle preferably has at least one recess running in the longitudinal direction and open towards the outside in the radial direction.

[0044] Due to the separate design of the nozzle needle and the control piston, it is not necessary to align the needle guide section with the control piston, as the needle guide section is assigned to the nozzle needle. Through at least one recess, which is open radially outward, the fuel can flow longitudinally in the nozzle body past the nozzle needle to at least one injection opening.

[0045] In one embodiment, the nozzle body has a concentric injection opening.

[0046] With a concentric injection opening, a sufficiently large flow cross-section can be provided, which can be particularly advantageous for a gaseous fuel.

[0047] In one embodiment, the nozzle body has a plurality of eccentrically arranged injection openings.

[0048] A plurality of eccentrically arranged injection openings can be advantageous, in particular for a liquid fuel, in order to provide a spatially uniformly distributed injection into the combustion chamber of the internal combustion engine.

[0049] In one embodiment, a cap is arranged at a downstream end of the nozzle body, which cap extends over the at least one injection opening and has a concentric or at least one eccentric opening.

[0050] The cap offers the advantage that the fuel emerging from the nozzle body through the at least one injection opening can flow into the combustion chamber of the internal combustion engine in a direction dependent on the orientation of the concentric or the at least one eccentric opening of the cap.

[0051] In one embodiment, the fuel chamber has a fuel supply section which has a larger diameter than the diameter of a control fluid supply section of the high-pressure control chamber.

[0052] In particular, in the case of a gaseous fuel, a sufficiently large flow cross-section can be provided through the fuel supply section.

[0053] In one embodiment, the hydraulic control device is designed to adjust the control piston along the longitudinal axis by changing the pressure in a control chamber, wherein the hydraulic control device has an intermediate valve with an intermediate valve member which, in a control open position, releases a first connection between a control fluid inlet connected to the high-pressure control chamber and the control chamber and, in a control closed position, interrupts the first connection between the control fluid inlet and the control chamber and separates the control chamber from a valve chamber except for a throttle passage, wherein the fuel injection valve has an electromagnetically actuated actuator arrangement for connecting the valve chamber to and separating the valve chamber from a low-pressure control fluid return.

[0054] By connecting the valve chamber to the low-pressure control fluid return, the intermediate valve member can be moved to the closed control position to move the control piston away from the injector seat and thus lift the nozzle needle from the injector seat. By separating the valve chamber from the low-pressure control fluid return, the intermediate valve member can be moved to the open control position to move the control piston toward the injector seat and thus press the nozzle needle onto the injector seat.

[0055] The connection of the valve chamber to and the separation of the valve chamber from the low-pressure control fluid return can be achieved by a plunger which is pressed by the actuator arrangement onto a low-pressure control fluid outlet of the valve chamber in order to close the low-pressure control fluid outlet and is lifted from the low-pressure control fluid outlet in order to open it.

[0056] A part of the control chamber is preferably arranged between the intermediate valve member and the control piston, so that the intermediate valve member and / or the control piston can be moved by changing the pressure in the control chamber.

[0057] A part of the valve chamber is preferably arranged on a side of the intermediate valve member facing away from the control chamber.

[0058] In one embodiment, the control piston has a guide section at an end facing away from the injection valve seat, which guide section is guided in a guide sleeve with a sliding fit, wherein the fuel injection valve has an intermediate part which, together with the guide sleeve and the control piston, delimits the control chamber, wherein the intermediate valve member is mushroom-shaped and has a shaft guided in a guide recess of the intermediate part and a head, wherein the intermediate valve has an intermediate valve seat formed on a side of the intermediate part facing the head and interacting with the head.

[0059] The mushroom-shaped intermediate valve member allows for stable control by the intermediate valve, e.g., compared to a disc-shaped intermediate valve member. Furthermore, the mushroom-shaped intermediate valve member offers the advantage of enabling precise control using a small amount of control fluid. The fuel injector therefore offers the possibility of utilizing the advantages of hydraulic control with an intermediate valve having a mushroom-shaped intermediate valve member due to the decoupling and interchangeability of the injection components for different fuels, e.g., a gaseous fuel or a liquid fuel.

[0060] Several of the alternative, desired green and climate-neutral fuels generally exhibit poor ignition properties and can require comparatively high ignition energy for clean combustion in piston internal combustion engines. This can be particularly the case when the combustion process, as in most large engines, is a process with self-ignition and simultaneous high compression, such as the diesel engine. Since the high compression results in higher engine efficiency, i.e., lower fuel consumption, this can lead to significant operating cost savings for large engines, which typically have several thousand operating hours per year at high load.

[0061] To ignite the alternative fuels during auto-ignition, a small injection of diesel fuel at high pressure is typically used. This can be optimally provided by a micro-pilot injector or by an injector that allows the engine to operate up to full load on diesel fuel and provides only a small amount of pilot fuel to ignite the alternative fuel when the engine generates the high load with the alternative fuel.

[0062] The hydraulic control system for the fuel injection valve disclosed herein can therefore advantageously also be operated with diesel fuel. A third, separate control fuel can then advantageously be omitted.

[0063] The throttle passage is preferably formed on the intermediate valve member, particularly preferably on the head of the intermediate valve member. However, the throttle passage can also be formed on the intermediate part. In further variants, the throttle passage can be formed between the intermediate valve member and another component, for example by a gap between the intermediate valve member and the intermediate part. The throttle passage formed on the intermediate valve member can open, on the side facing away from the control chamber, into a blind hole cut out on the intermediate valve member and belonging to the valve chamber. The throttle passage is preferably formed in the intermediate valve member adjacent to the control chamber. The throttle passage and the blind hole are preferably formed centrally to the longitudinal axis. This means that on the one hand the throttle passage can be formed with the desired length and on the other hand the blind hole can form part of the valve chamber.

[0064] In one embodiment, the intermediate valve member releases a second connection between the control fluid inlet and the valve chamber in the control open position of the intermediate valve member and interrupts the second connection between the control fluid inlet and the valve chamber in the control closed position of the intermediate valve member.

[0065] Because the intermediate valve member releases a second connection between the control fluid inlet and the valve chamber in the open position, the valve chamber can be filled with control fluid via the second connection, which enables a faster opening movement of the intermediate valve member. In particular, the second connection can improve the filling of the valve chamber compared to a fuel injection valve, in which the filling of the valve chamber takes place, for example, solely from the control chamber via a throttle passage. Advantageously, the valve chamber can therefore be filled via the second connection even with a small opening movement of the intermediate valve member.As far as the throttle passage is concerned, it can advantageously be sufficient if the flow of control fluid from the control chamber into the valve chamber through the throttle passage causes the initially small opening movement of the intermediate valve member, since the valve chamber can then be filled with a large quantity of control fluid via the second connection. By interrupting the second connection between the control fluid inlet and the valve chamber in the closed position of the intermediate valve member, disadvantageous loss of fuel and wear due to the expansion of the control fluid from the high-pressure chamber into the valve chamber during the injection process can be reduced or minimized, while by opening the second connection, rapid filling of the valve chamber for the opening movement of the intermediate valve member can be achieved.

[0066] List of characters

[0067] Embodiments of the invention are explained in more detail with reference to the following figures and the associated description. They show schematically:

[0068] Fig.l shows a longitudinal section through an embodiment of a fuel injection valve;

[0069] Fig.2 is an enlarged view of a section of the longitudinal section from Fig.l;

[0070] Fig.3 another longitudinal section of the

[0071] Fuel injection valve from Fig.l, wherein the sectional plane is rotated by 90° compared to Fig.l;

[0072] Fig.4 is an enlarged view of a section of the longitudinal section from Fig.3;

[0073] Fig.5 is a further enlarged view of the section from Fig.4 in the area of ​​the intermediate valve;

[0074] Fig. 6 shows a longitudinal section of another embodiment of a fuel injection valve. Description of exemplary embodiments

[0075] In the description of the figures, corresponding

[0076] Parts of the embodiments use the same reference symbols.

[0077] Figure 1 shows a longitudinal section through an embodiment of a fuel injection valve 10. 1 with a housing 12 extending along a longitudinal axis L. The housing 12 has a fuel inlet 21 and a nozzle body 13 with an injection valve seat 131. The nozzle body 13 further has a centrally arranged injection opening 132 through which fuel can escape from the nozzle body 13 for injecting fuel into the combustion chamber of an internal combustion engine. A fuel chamber 22 runs in the housing 12 from the fuel inlet 21 to the injection valve seat 131. At the downstream end of the nozzle body 13, a cap 14 is arranged, which extends over the central injection opening 132 of the nozzle body 13 and has a concentric opening 141. The cap 14 is arranged such that an axial gap exists between the cap 14 and the nozzle body 13.

[0078] A control piston 51 is arranged in the housing 12 and is adjustable along the longitudinal axis L. This control piston 51 is acted upon by a control pressure spring 52 with a closing force directed in the direction of the injection valve seat 131. The control piston 51 is guided with an end section opposite the injection valve seat 131 in a guide sleeve 18, against which one end of the control pressure spring 52 is supported. The fuel injection valve 10.1 further has a hydraulic control device with an intermediate valve 53 for controlling the adjustment of the control piston 51.

[0079] In the nozzle body 13, a nozzle needle 61 is arranged at the end of the control piston 51 facing the injection valve seat 131. The nozzle needle 61 bears against the control piston 51 with an end face facing away from the injection valve seat 131, wherein the nozzle needle 61 is pressed by an injection pressure spring 62 against an end face of the control piston 51 facing the injection valve seat 131.

[0080] The housing 12 further has an actuator receiving body 16 in which an electromagnetically actuable actuator arrangement 43 is accommodated. An intermediate body 15, in which the control compression spring 52 and a part of the control piston 51 are arranged, is adjacent to the actuator receiving body 16. The nozzle body 13 is adjacent to the downstream end face of the intermediate body 15, the intermediate body 15 and the nozzle body 13 being detachably fastened to the actuator receiving body 16 by a union nut 17. By loosening the union nut 17, the nozzle body 13 and the nozzle needle 61 can therefore be replaced. A low-pressure control fluid return 42 is also arranged in the housing 12, the function of which is described further below in connection with Figure 5.

[0081] Figure 2 shows an enlarged view of the longitudinal section from Figure 1. The intermediate body 15 has a central guide bore 151 in which an actuating section 512 of the control piston 51, which is arranged at its end facing the injection valve seat 131, is guided with a sliding fit. The control compression spring 52, which acts on the control piston 51 with a closing force directed in the direction of the injection valve seat 131, rests with a lower end on a shoulder 511 of the control piston 51 and with an upper end on the guide sleeve 18, in which a guide section 514 of the control piston 51 is guided with a sliding fit.

[0082] The downstream end face 513 of the control piston 51 and the upstream end face 611 of the nozzle needle 61 abut one another, with the injection compression spring 62, which presses the nozzle needle 61 against the control piston 51, abutting with a lower end against a shoulder 134 of the nozzle body 13 and with an upper end against a shoulder 612 of the nozzle needle 61. The upstream end face 611 of the nozzle needle 61 has a larger area than the downstream end face 513 of the control piston 51. In certain embodiments, however, it is also possible for the upstream end face of the nozzle needle to have a smaller area than the downstream end face of the control piston. Due to the separate design of the nozzle needle 61 and the control piston 51 and the design of the end faces 611 and 513, there is a tolerance in the radial orientation of the nozzle needle 61 and the control piston 51 to one another.In particular, the nozzle needle 61 and the nozzle body 13 do not need to be precisely aligned with the guide bore 151 of the intermediate body 15, as would be necessary, for example, with a one-piece control injection piston. This simplifies the replacement of the nozzle needle 61 and the nozzle body 13.

[0083] The nozzle needle 61 is in a needle guide section 133 of the

[0084] Nozzle body 13 and has a plurality of recesses 613 running in the longitudinal direction L and open outwards in the radial direction, through which the fuel can flow past the nozzle needle 61 in the longitudinal direction L.

[0085] The intermediate valve 53 has a mushroom-shaped intermediate valve member 54 and is designed to adjust the control piston 51 along the longitudinal axis so that the control piston 51 can move the nozzle needle along the longitudinal axis.

[0086] Figure 3 shows a further longitudinal section of the fuel injector 10.1 from Figure 1, wherein the sectional plane is rotated by 90° about the longitudinal axis L compared to Figure 1. The housing 12 has a control fluid inlet 31 and a high-pressure control chamber 32, which is connected to the control fluid inlet 31. A portion of the high-pressure control chamber 32 is arranged in the intermediate body 15, and another portion is arranged in the actuator receiving body 16.

[0087] For gaseous fuels, such as hydrogen or methane, the gas injection pressure is typically comparatively low. For example, the gas injection pressure for hydrogen can be in the range of approximately 10–60 bar, in certain cases up to approximately 100 bar. For methane, the gas injection pressure can also be in these ranges, in other specific cases above approximately 100 bar, and in other specific cases up to approximately 250 bar. The control fluid pressure in the high-pressure control chamber is then typically approximately 70–200 bar higher than the gas injection pressure.

[0088] With liquid fuels, such as methanol or derivatives thereof such as dimethyl ether (DME) or oxymethylene ether (OME), or ammonia or diesel, the fuel injection pressure is typically comparatively higher. For example, the fuel injection pressure with methanol or derivatives thereof such as dimethyl ether (DME) or oxymethylene ether (OME) can be around 400-600 bar, in certain cases up to around 1100 bar. The control fluid pressure in the high-pressure control chamber is then typically around 100-300 bar higher than the fuel injection pressure. With ammonia, the fuel injection pressure is typically above around 1000 bar, in certain cases up to 1300 bar. Similar to diesel, the fuel injection pressure can vary depending on engine load and speed and in certain cases can therefore be lower than around 1000 bar. The control fluid pressure in the high-pressure control chamber is then typically 10-20% higher than the fuel injection pressure.The control fluid pressure in the high-pressure control chamber can therefore be similar for ammonia as for diesel operation.

[0089] A leakage discharge 72 is arranged in the housing 12, which discharges any leakage occurring in the guide bore 151 to the leakage outlet 73. The leakage discharge 72 is shown again in the enlarged illustration in Figure 4. The guide bore 151 of the intermediate body 15 has a circumferential annular space 71, from which the leakage discharge 72 runs to the leakage outlet 73 (shown in Figure 3), so that any leakage occurring through the guide bore 151 despite the sliding fit of the actuating section 512 of the control piston 51 can be discharged, and the fluidic separation between the high-pressure control chamber 32 and the fuel chamber 22 can be ensured or improved.In certain embodiments, the leakage discharge 72 may have a check valve (not shown) which is designed to open at an opening pressure lying between the control fluid inlet pressure of the high-pressure control chamber 32 and the fuel chamber pressure of the fuel chamber 22, wherein the opening pressure is preferably closer to the fuel chamber pressure than to the control fluid inlet pressure.

[0090] For gaseous fuels, such as hydrogen or methane, where the fuel chamber pressure is comparatively low, the low-pressure control fluid return can be combined with the leakage discharge in certain configurations. The low-pressure control fluid return and the leakage discharge can then have a common control fluid outlet. The low-pressure control fluid return pressure will then be the same as the leakage discharge return pressure, which corresponds to the opening pressure of the check valve. With such a configuration, one outlet can advantageously be eliminated.

[0091] The intermediate body 15 has a transverse wall 152 which axially delimits the high-pressure control chamber 32. The transverse wall 152 further provides a spatial separation between the high-pressure control chamber 32 and the fuel chamber 22. The transverse wall 152 of the intermediate body 15 and the actuating section of the control piston 51, which is guided with a sliding fit in the guide bore 151, achieve a fluidic separation between the high-pressure control chamber 32 and the fuel chamber 22.

[0092] Figure 5 shows a further enlarged view of the section from Figure 4 in the area of ​​the intermediate valve 53. The intermediate valve 53 has a mushroom-shaped intermediate valve member 54 with a head 541 and a shaft 542. The shaft 542 is guided in a guide recess of an intermediate part 56. The guide sleeve 18 and the guide section 514 of the control piston, together with the intermediate part 56, delimit a control chamber 55. The intermediate valve 53 has an intermediate valve seat formed on a side of the intermediate part 56 facing the head 541, which is designed to cooperate sealingly with the head 541. The intermediate valve member 54 is movable in the axial direction between a control open position and a control closed position. In the control open position, a first connection between a control fluid inlet 321 connected to the high-pressure control chamber 32 and the control chamber 55 is released.In the control closed position, the first connection between the control fluid inlet 321 and the control chamber 55 is interrupted. Furthermore, in the control closed position, the control chamber 55 is separated from a valve chamber 44 except for a throttle passage 544. The valve chamber 44 is connected to the low-pressure control fluid return 42 or separated from the low-pressure control fluid return 42 by raising or lowering a tappet 431 of the electromagnetically actuated actuator arrangement 43, which is shown in Figure 1. The intermediate valve member 54 also has a bore 543 which is connected to the valve chamber 44 and which borders the throttle passage 544.

[0093] The structure of the intermediate valve 53 essentially corresponds to the embodiments shown in the publications WO 2016 / 041739 A1, WO 2020 / 260285 A1, or WO 2021 / 165275 A1, the disclosures of which are incorporated by reference into the present description. However, it is also conceivable that other known hydraulic control devices, such as those shown in WO 2021 / 110663 A1 or EP 0 753 658 B1, can be used for the intermediate valve 53, and the disclosures of which are incorporated by reference into the present description.

[0094] Figure 6 shows a representation of a further embodiment of a fuel injection valve 10. 2 in longitudinal section. The housing 12 has a nozzle body 13, an intermediate body 15 and an actuator receiving body 16, to which the nozzle body 13 and the intermediate body 15 are releasably fastened by means of a union nut 17. The nozzle needle 61 is guided in a downstream region in a needle guide section 133 of the nozzle body 13 and has a plurality of recesses running in the longitudinal direction and open outwards in the radial direction.

[0095] In contrast to the fuel injection valve shown in Figures 1-5, the nozzle body 13 has a guide bore 135 in which both an adjusting section 614 of the nozzle needle 61 and an adjusting section 512 of the control piston 51 are guided with a sliding fit. Due to the guidance of the adjusting section 614 of the nozzle needle 61 in the guide bore 135, embodiments are also possible in which the nozzle needle 61 is not guided in the section 133 of the nozzle body 13. In these embodiments, there is then an intermediate space between the nozzle needle 61 and the lower section 133 of the nozzle body 13, through which space the fuel can flow. Between the control piston 51 and the nozzle needle 61, an actuating chamber 136 is arranged in the nozzle body 13, which is radially delimited by the nozzle body 13 and axially by the control piston 51 and the nozzle needle 61 and which is fluidically sealed.The guide bore 135 has an annular space 71, from which, as in the embodiments according to Figure 3 or Figure 4, a leakage discharge runs to a leakage outlet (not visible in Figure 6) and via which a leakage occurring in the guide bore 135 can be discharged.

[0096] As an alternative to the annular space 71, the leakage can also be discharged from the control space 136, so that the annular space 71 can be omitted.

[0097] During injector assembly, a slight misalignment, e.g. in the range of a few hundredths of a millimeter, can occur between the nozzle body 13, the intermediate body 15, and the actuator receiving body 16. With the actuating section 512 of the one-piece control piston 51 being guided in a close sliding fit in the nozzle body 13, and because the guide sleeve 18 for the control piston 51 is located in the actuator receiving body 16, the guide sleeve 18 of the control piston 51 is not guided tightly radially. As can be seen in Fig. 6, the guide sleeve 18 therefore has radial play with the actuator receiving body 16.

[0098] The high-pressure control chamber 32 is axially delimited by the end face of the nozzle body 13 adjacent to the intermediate body 15. With the actuating sections 512, 614 of the control piston 51 and the nozzle needle 61, which are guided with a sliding fit in the guide bore 135, a fluidic separation between the high-pressure control chamber 32 and the fuel chamber 22 is achieved. The nozzle needle 61 cooperates with an injection valve seat 131 of the nozzle body 13 to inject fuel into the combustion chamber of the internal combustion engine. For this purpose, a plurality of eccentrically arranged injection openings 132 are arranged in the nozzle body 13 downstream of the injection valve seat 131. The arrangement of the injection openings 132 shown in Figure 6 is typically advantageous for liquid fuels.

[0099] The fuel injector 10.1 shown in Figures 1-5 is particularly advantageous for a gaseous fuel, while the fuel injector 10.2 shown in Figure 6 can be used particularly with a liquid fuel. The nozzle body 13 and the nozzle needle 61 can be replaced in both fuel injectors 10.1 and 10.2 depending on the requirements of the fuel used. The hydraulic control with the intermediate valve 53, however, can be retained regardless of the fuel used.

[0100] Several of the alternative, desired green and climate-neutral fuels generally exhibit poor ignition properties and can require comparatively high ignition energy for clean combustion in the internal combustion engine. This can be particularly the case when the combustion process, as in most large engines, is a process with self-ignition and simultaneous high compression, such as the diesel engine. Since the high compression results in higher engine efficiency, i.e., lower fuel consumption, this can lead to significant operating cost savings for large engines, which typically have several thousand operating hours per year at high load.

[0101] To ignite the alternative fuels during auto-ignition, a small injection of diesel fuel at high pressure is typically used. This can be optimally provided by a micro-pilot injector or by an injector that allows engine operation up to full load on diesel fuel and provides only a small amount of pilot fuel to ignite the alternative fuel when the engine generates the high load with the alternative fuel.

[0102] The hydraulic controls disclosed here for the fuel injection valves shown in Figures 1-6 can therefore advantageously also be operated with diesel fuel. A third, separate control fuel can then advantageously be omitted.

Claims

Patent claims 1. Fuel injection valve (10.1, 10.2) for the intermittent injection of fuel into a combustion chamber of an internal combustion engine, comprising a housing (12) extending along a longitudinal axis (L) and having a control fluid inlet (31), a fuel inlet (21), and a nozzle body (13) with an injection valve seat (131), a high-pressure control chamber (32) arranged in the housing and connected to the control fluid inlet, a fuel chamber (22) arranged in the housing and extending from the fuel inlet to the injection valve seat, a control piston (51) arranged in the housing so as to be adjustable along the longitudinal axis, which control piston is acted upon by a control pressure spring (52) with a closing force directed towards the injection valve seat, a hydraulic control device (53) for controlling the adjustment of the control piston along the longitudinal axis,a nozzle needle (61) arranged at an end of the control piston facing the injection valve seat, which is arranged at least partially in the nozzle body and is designed to communicate with the injection valve seat for injecting fuel into the combustion chamber of the, Combustion engine to work together, whereby the nozzle needle can be moved along the longitudinal axis by adjusting the control piston.

2. Fuel injection valve (10.1, 10.2) according to claim 1, characterized in that the high-pressure control chamber (32) and the fuel chamber (22) are fluidically separated.

3. Fuel injection valve (10.1, 10.2) according to claim 1 or 2, characterized in that the fuel injection valve has an intermediate body (15) in which the control piston (51) and the high-pressure control chamber (32) are at least partially arranged, wherein the nozzle body (13) adjoins a downstream end face of the intermediate body.

4. Fuel injection valve (10.1, 10.2) according to claim 3, characterized in that the nozzle body (13) or the intermediate body (15) has a guide bore (151, 135) in which an adjusting section (512) of the Control piston (51), which is arranged at its end facing the injection valve seat (131) and / or in which an adjusting section (614) of the nozzle needle (61), which is arranged at its end facing away from the injection valve seat, is / is guided in a sliding fit.

5. Fuel injection valve (10.1, 10.2) according to claim 4, characterized in that the guide bore (151, 135) has a circumferential annular space (71), and the fuel injection valve has a leakage outlet (73) and a leakage discharge (72) which runs from the annular space to the leakage outlet.

6. Fuel injection valve according to claim 5, characterized in that the leakage discharge has a check valve which is designed to open at an opening pressure lying between the control fluid inlet pressure and the fuel chamber pressure, wherein the opening pressure is preferably closer to the fuel chamber pressure than to the control fluid inlet pressure.

7. Fuel injection valve according to claim 6, characterized in that the opening pressure is less than 10% or approximately 10% higher than the fuel chamber pressure.

8. Fuel injection valve according to claim 6 or 7, characterized in that the check valve is arranged within the housing.

9. Fuel injection valve according to claim 6 or 7, characterized in that the check valve is arranged outside the housing.

10. Fuel injection valve (10.1) according to one of the preceding claims, characterized in that an injection pressure spring (62) is arranged in the nozzle body (13), which presses the nozzle needle (61) onto the control piston (51).

11. Fuel injection valve (10.2) according to one of the preceding claims, characterized in that between the control piston (51) and the nozzle needle (61) there is a radially through the nozzle body (13) or through the intermediate body and axially through the control piston (51) and the nozzle needle (61) is arranged in a limited, fluidically sealed actuating chamber (136).

12. Fuel injection valve (10.1, 10.2) according to one of the preceding claims, characterized in that the fuel injection valve has an actuator receiving body (16) to which the nozzle body (13) is releasably fastened, preferably with a union nut (17), such that the nozzle body and the nozzle needle (61) are interchangeable.

13. Fuel injection valve (10.1, 10.2) according to one of the preceding claims, characterized in that the nozzle needle (61) is guided in a needle guide section (133) of the nozzle body (13), wherein the nozzle needle preferably has at least one recess (613) extending in the longitudinal direction and open outwards in the radial direction.

14. Fuel injection valve (10.1) according to one of the preceding claims, characterized in that the nozzle body (13) has a concentric injection opening (132).

15. Fuel injection valve (10.2) according to one of the claims 1 to 13, characterized in that the nozzle body has a plurality of eccentrically arranged injection openings (132).

16. Fuel injection valve (10.1) according to one of the preceding claims, characterized in that a cap (14) is arranged at a downstream end of the nozzle body (13), which cap extends over the at least an injection opening (132) extends and has a concentric or at least one eccentric opening (141).

17. Fuel injection valve (10.1) according to one of the preceding claims, characterized in that the fuel chamber (22) has a fuel supply section which has a larger diameter than the diameter of a control fluid supply section of the high-pressure control chamber (32).

18. Fuel injection valve (10.1, 10.2) according to one of the preceding claims, characterized in that the hydraulic control device (53) is designed to adjust the control piston (51) along the longitudinal axis (L) by changing the pressure in a control chamber (55), wherein the hydraulic control device has an intermediate valve (53) with an intermediate valve member (54) which, in a control open position, releases a first connection between a control fluid inlet (321) connected to the high-pressure control chamber (32) and the control chamber (55), and, in a control closed position, interrupts the first connection between the control fluid inlet and the control chamber and separates the control chamber from a valve chamber (44) except for a throttle passage (544), wherein the fuel injection valve has an electromagnetically actuated actuator arrangement (43) for connecting the valve chamber to and separating the valve chamber from a low-pressure control fluid return (42).

19. Fuel injection valve (10.1, 10.2) according to claim 18, characterized in that the control piston (51) has a guide section (514) at an end facing away from the injection valve seat (131), which guide section is guided in a sliding fit in a guide sleeve (18), wherein the fuel injection valve has an intermediate part (56) which, together with the guide sleeve and the control piston, delimits the control chamber (55), wherein the intermediate valve member (54) is mushroom-shaped and has a shaft (542) guided in a guide recess in the intermediate part and a head (541), wherein the intermediate valve (53) has an intermediate valve seat formed on a side of the intermediate part facing the head and interacting with the head.

20. Fuel injection valve according to claim 19, characterized in that the intermediate valve member releases a second connection between the control fluid inlet and the valve chamber in the control open position of the intermediate valve member and interrupts the second connection between the control fluid inlet and the valve chamber in the control closed position of the intermediate valve member.

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