Fuel injector

Abstract

The fuel injector (10.1) includes a housing with a nozzle body having a control fluid inlet, a fuel inlet, and an injection seat; a high-pressure control chamber (32) located within the housing and connected to the control fluid inlet; a fuel chamber (22) located within the housing and extending from the fuel inlet to the injection seat; a nozzle body (10.1) connected to the control fluid inlet; and a fuel chamber (22) located within the housing and extending from the fuel inlet to the injection seat; a control piston (51) located within the housing and adjustable along a longitudinal axis (L), on which a control pressure spring having a closing force toward the injection seat acts; a hydraulic control device for adjusting the control piston along the longitudinal axis; and a nozzle needle located at the end of the control piston facing the injection seat and configured to cooperate with the injection seat to inject fuel into the combustion chamber of an internal combustion engine, the nozzle needle being movable by adjusting the control piston along the longitudinal axis.

Description

Technical Field

[0001] The present invention relates to a fuel injection valve for intermittently injecting fuel into a combustion chamber of an internal combustion engine.

Background Art

[0002] Fuel injection valves are used to inject fuel into the combustion chambers of internal combustion engines, particularly diesel engines. In recent years, in addition to conventional diesel fuel, various gaseous or liquid fuels such as hydrogen, methane, methanol, and ammonia have been proposed as environmentally friendly and low-pollution alternative fuels.

[0003] Due to the large variety of available fuels, it may be advantageous to adapt the fuel injection valve to the possible variations. One option is to provide a multi-fuel injection valve that can be used with multiple fuels. One such option is a dual-fuel system that can use, for example, liquid fuels such as diesel oil or marine gas oil, or gaseous fuels such as hydrogen, methane, or biogas.

[0004] International Publication No. 2015 / 101406 describes a dual-fuel fuel injection system comprising a first axially stroke-controllable nozzle needle for supplying liquid fuel through a first nozzle arrangement of a dual-fuel fuel injector. The first nozzle needle is preferably housed in the nozzle body of the fuel injector. The dual-fuel fuel injector further comprises a plurality of axially stroke-controllable second nozzle needles (e.g., two, three, four, five or more second nozzle needles) arranged around the first nozzle needle for injecting gaseous fuel through a second nozzle arrangement of the dual-fuel fuel injector. In particular, a configuration is provided comprising a centrally located first nozzle needle and second nozzle needles eccentrically thereto, preferably concentrically arranged with respect to the first nozzle needle. Similar to the first nozzle needle, the second nozzle needles are also preferably housed in the nozzle body. Within the second nozzle arrangement, each second nozzle needle is assigned, for example, one or more gas injection nozzle openings on the injector through which gas can be released. [Overview of the project]

[0005] Known multi-fuel injection systems that use multiple nozzle needles, such as the dual fuel injection system described at the beginning, are associated with correspondingly high spatial requirements and complexity. The high spatial requirements stem from the existence of multiple independent circuits for the first and second nozzle needles, even if only a specific fuel is required for a particular application. Furthermore, these systems are relatively inflexible because the number and structure of the nozzle needles and nozzle bodies are fixed and cannot be changed. This can be particularly disadvantageous, as it is often not possible to know in advance which fuel will be needed for a particular application. For example, the injector described in International Publication No. 2015 / 101406 is complex in design, resulting in relatively high manufacturing and maintenance costs. Moreover, complex designs can compromise reliability in long-term operation. Since internal combustion engines equipped with such injection systems are used in mining, marine, and other heavy-duty applications, engine shutdown due to injection system failure can immediately incur significant costs. Therefore, the reliability and durability of the injection system are particularly desirable.

[0006] In this regard, it is desirable to provide a fuel injector that has a simpler structure, enhances adaptability to different fuels, and offers reliable controllability of the injection process.

[0007] Therefore, an object of the present invention is to provide a fuel injection valve that improves the prior art at least partially.

[0008] This objective is achieved by a fuel injector having the features of the independent claim. Advantageous embodiments of the present invention are provided in the dependent claims, as well as herein and in the drawings.

[0009] The present invention relates to a fuel injector for intermittently injecting fuel into the combustion chamber of an internal combustion engine, the fuel injector having a nozzle body having a control fluid inlet, a fuel inlet, and an injection valve seat, a housing extending along a longitudinal axis, a high-pressure control chamber located within the housing and connected to the control fluid inlet, a fuel chamber located within the housing and extending from the fuel inlet to the injection valve seat, a control piston located within the housing and adjustable along a longitudinal axis, on which a control pressure spring acts to exert a closing force toward the injection valve seat, a hydraulic control device for controlling the adjustment of the control piston along the longitudinal axis, and a nozzle needle located at the end of the control piston facing the injection valve seat, at least a portion of which is located within the nozzle body and configured to cooperate with the injection valve seat to inject fuel into the combustion chamber of an internal combustion engine, the nozzle needle being movable by adjusting the control piston along the longitudinal axis.

[0010] Compared to known solutions that control the nozzle needle position by adjusting the nozzle needle adjustment mechanism, providing separate control pistons and control fluids in the high-pressure control chamber allows for more precise control and, in particular, enables design independent of the characteristics of the fuel used in each case. The nozzle needle, injection seat, and / or injection opening can be adapted according to the fuel requirements in the fuel chamber.

[0011] Therefore, in this fuel injector, the control components and injection components can be structurally separated from each other, at least in substantial terms. This improves the ability to adapt to the requirements of the control system or fuel. Specifically, this adaptability is enhanced in both the control components, such as the control piston and the control fluid in the high-pressure control chamber, and the injection components, such as the nozzle needle, injection seat, at least one injection opening, and fuel chamber.

[0012] For example, by separating the control components from the injection components, a fuel injector can be operated with both gaseous fuel and a liquid control fluid for hydraulic control. However, it can also be used with liquid fuel by replacing the injection components.

[0013] The separation design of the control piston and nozzle needle offers the further advantage of providing independent guides for the control piston and nozzle needle. Because the control piston and nozzle needle are designed as separate components, slight misalignments of the control piston and nozzle needle during injector assembly have only minor or negligible effects. Since the control piston and nozzle needle are guided by their respective guides, slight misalignments do not cause harmful friction within each guide. This ensures perfect, low-friction operation. vinegar.

[0014] Preferably, the end face of the control piston facing the injection valve seat interacts with the end face of the nozzle needle facing away from the injection valve seat, thereby moving the nozzle needle. In a modified example, 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 another modified example, 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 yet another modified example, 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.

[0015] Preferably, the high-pressure control chamber and the fuel chamber are fluidly separated.

[0016] Fluid separation of the high-pressure control chamber and the fuel chamber makes it possible to provide a circuit that is fluidly separated from the control fluid and fuel. This improves the separability of the control components and the injection components. In this context, those skilled in the art will understand that fluid separation can be achieved while minimizing (keeping within acceptable limits) leakage from the high-pressure control chamber to the fuel chamber.

[0017] In one embodiment, the fuel injector has an intermediate body, a control piston and a high-pressure control chamber are at least partially arranged, and the nozzle body is adjacent to the downstream end face of the intermediate body.

[0018] The intermediate can accommodate a control piston so that its end facing the injection valve seat can interact with the nozzle needle.

[0019] In one embodiment, the intermediate has a lateral wall that axially separates the high-pressure control chamber and the nozzle body. The lateral wall of the intermediate can provide spatial separation between the high-pressure control chamber and the fuel chamber.

[0020] In one embodiment, the nozzle body or intermediate has a guide hole through which an adjustment part of a control piston, located at the end facing the injection valve seat, and / or an adjustment part of a nozzle needle, located at the end away from the injection valve seat, are guided by a sliding fit.

[0021] The sliding fit within the guide bore enables fluid separation between the high-pressure control chamber and the fuel chamber. Furthermore, the guide bore can provide a receiving portion or passage for accommodating the adjustment portion of the control piston and / or nozzle needle, respectively, allowing them to contact or interact with each other. In a variation, for example, the adjustment portion of the control piston can be routed into the guide bore, and the control piston can be routed through the guide bore to protrude into the nozzle body and contact the nozzle needle. In another variation, the adjustment portion of the nozzle needle can be routed into the guide bore, and the nozzle needle can be routed through the guide bore to protrude into an intermediate and contact the control piston. In yet another variation, both the adjustment portion of the control piston and the adjustment portion of the nozzle needle are configured to protrude into the guide bore, and the control piston and nozzle needle contact directly or indirectly (e.g., via the adjustment chamber) within the guide bore.

[0022] In one embodiment, the guide hole has a circumferential annular space, and the fuel injection valve includes a leak outlet and a leak drainage channel leading from the annular space to the leak outlet.

[0023] Control fluid generated from leaks in the guide holes is collected in an annular space and discharged to the leak outlet via a leak discharge pipe. This minimizes or reduces the leakage of control fluid from the high-pressure control chamber through the guide holes to the fuel chamber.

[0024] In one embodiment, the leakage discharge passage includes a check valve designed to open at an opening pressure between the control fluid inlet pressure and the fuel chamber pressure. This opening pressure is preferably closer to the fuel chamber pressure than the control fluid inlet pressure.

[0025] In one embodiment, the opening pressure is subtracted by 10% or about 10% higher than the fuel chamber pressure.

[0026] Preferably, the leakage discharge passage mainly or exclusively discharges the control fluid. Preferably, the leakage discharge passage does not discharge any fuel.

[0027] Therefore, the check valve set to the corresponding opening pressure can be used to operate the leakage discharge passage when leakage needs to be discharged. By providing the leakage discharge passage and the check valve, the sealing oil can be advantageously omitted.

[0028] In a multi-cylinder internal combustion engine, an individual check valve can be arranged inside / above each fuel injection valve. As a variant, a common check valve can be arranged inside / above a collective leakage discharge pipe that collects leakage discharges from a plurality of fuel injection valves.

[0029] The check valve can be arranged inside or outside the fuel injection valve housing.

[0030] The check valve can be designed as a mechanical spring valve having a specific set value or adjustable opening pressure. Alternatively, it can also be designed as an electromagnetic control valve having an electrically or electronically adjustable opening pressure. The electrically or electronically adjustable opening pressure can be flexibly set to the optimal opening pressure required according to the operating state of the internal combustion engine. For example, when changing the control fluid inlet pressure according to the load and engine speed to more appropriately control the fuel injection of the internal combustion engine, the opening pressure can be changed.

[0031] Preferably, an injection pressure spring is arranged inside the nozzle body to press the nozzle needle against the control piston.

[0032] The injection pressure spring can ensure that the nozzle needle follows the movement of the control piston, particularly when the control piston moves away from the injector seat to open the fuel injector. Preferably, the injection pressure spring is designed so that the end face of the nozzle needle contacts the end face of the control piston. The injection pressure spring is particularly advantageous when using gaseous fuels and liquid control fluids, as the pressure in the fuel chamber is usually significantly lower than in the high-pressure control chamber.

[0033] In one embodiment, a fluidly closed adjustment chamber is positioned between the control piston and the nozzle needle, and this adjustment chamber is surrounded radially by the nozzle body or intermediate and axially by the control piston and the nozzle needle.

[0034] In this context, a person skilled in the art will understand that the control chamber is fluidly sealed except for minor (acceptable) leaks.

[0035] In the case of liquid fuels in particular, the adjustment chamber is especially advantageous because sufficient pressure is usually present in the fuel chamber, allowing the nozzle needle to be adjusted via the adjustment chamber through the axial movement of the control piston.

[0036] In one embodiment, the fuel injector has an actuator receiving portion to which the nozzle body is preferably detachably fixed by a cap nut, thereby allowing the nozzle body and nozzle needle to be replaced.

[0037] The interchangeability of the nozzle body and nozzle needle offers the advantage of easily adapting the fuel injector to different fuels. Control components do not need to be changed, and adaptability is simplified, especially since the control circuit is separated from the injection components and fuel circuit. Depending on the fuel, fuel-appropriate injection components can be used, such as a nozzle body with an adapted injection seat, injection opening, and nozzle needle.

[0038] Therefore, fuel injectors can be easily adapted to a variety of applications.

[0039] In one embodiment, both the intermediate and the nozzle are detachably fixed to the actuator receptor using a cap nut. The cap nut allows the nozzle to be pressed against the intermediate and the intermediate against the actuator receptor in a known manner.

[0040] In one embodiment, the nozzle body is detachably fixed to the intermediate body by a cap nut.

[0041] In one embodiment, the nozzle needle is guided within a needle guide portion of the nozzle body. Here, the nozzle needle preferably has at least one longitudinally extending recess that opens radially outward.

[0042] Because the nozzle needle and control piston are designed separately, the needle guide is associated with the nozzle needle, eliminating the need to align the needle guide with the control piston. At least one recess opening radially outward allows fuel to pass over the nozzle needle and flow longitudinally within the nozzle body to reach at least one injection opening.

[0043] In one embodiment, the nozzle body has concentric spray openings.

[0044] The concentric injection openings can provide a sufficiently large flow cross-sectional area, which is particularly advantageous for gaseous fuels.

[0045] In one embodiment, the nozzle body has a plurality of eccentrically arranged spray openings.

[0046] Multiple eccentrically positioned injection openings are particularly advantageous for liquid fuels in order to provide spatially uniform injection into the combustion chamber of an internal combustion engine.

[0047] In one embodiment, a cap is positioned at the downstream end of the nozzle body, and this cap covers at least one spray opening and has a concentric opening or at least one eccentric opening.

[0048] This cap offers the advantage that fuel ejected from the nozzle body through at least one injection opening flows directly into the combustion chamber of the internal combustion engine in a direction dependent on the orientation of the concentric opening or at least one eccentric opening of the cap.

[0049] In one embodiment, the fuel chamber includes a fuel supply section having a diameter larger than the diameter of the control fluid supply section of the high-pressure control chamber.

[0050] In particular, in the case of gaseous fuels, the fuel supply unit can provide a sufficiently large flow cross-sectional area.

[0051] In one embodiment, the hydraulic control device is configured to move a control piston along its longitudinal axis by changing the pressure in the control chamber. This hydraulic control device includes an intermediate valve, which has an intermediate valve member that, in the control open position, opens a first connection passage between the control fluid inlet connected to the high-pressure control chamber and the control chamber, and in the control closed position, closes the first connection between the control fluid inlet and the control chamber, separating the control chamber from the valve chamber except for the throttle passage. Here, the fuel injection valve includes an electromagnetically actuated actuator arrangement for connecting the valve chamber to the low-pressure control fluid return and for separating the valve chamber from the low-pressure control fluid return.

[0052] By connecting the valve chamber to the low-pressure control fluid return, the intermediate valve member can be moved to the controlled closed position, and the control piston can be moved away from the injection valve seat, thereby lifting the nozzle needle away from the injection valve seat. By separating the valve chamber from the low-pressure control fluid return, the intermediate valve member can be moved to the controlled open position, the control piston can be moved towards the injection valve seat, and the nozzle needle can be pressed against the injection valve seat.

[0053] The valve chamber is connected to and disconnected from the low-pressure control fluid return via a tappet. This tappet is pressed against the low-pressure control fluid outlet of the valve chamber by an actuator mechanism to close the low-pressure control fluid outlet, and is also lifted from the low-pressure control fluid outlet to open it.

[0054] Preferably, a portion of the control chamber is positioned between the intermediate valve member and the control piston, thereby allowing the intermediate valve member and / or the control piston to be moved by changing the pressure inside the control chamber.

[0055] It is preferable that a portion of the valve chamber be located on a side away from the control chamber of the intermediate valve member.

[0056] In one embodiment, the control piston has a guide portion at an end away from the injection valve seat, the guide portion is guided by sliding fitting within a guide sleeve, the fuel injection valve has an intermediate portion, the intermediate portion together with the guide sleeve and the control piston to define the control quality, the intermediate valve member is mushroom-shaped and has a shaft portion guided into a guide recess of the intermediate portion and a head portion, the intermediate valve has an intermediate valve seat formed on the side facing the head portion of the intermediate portion and cooperating with the head portion.

[0057] This mushroom-shaped intermediate valve member enables more stable control by the intermediate valve compared to, for example, a disc-shaped intermediate valve member. Furthermore, the mushroom-shaped intermediate valve member offers the advantage of precise control with a small amount of control fluid. Therefore, fuel injectors offer the possibility of leveraging the advantages of hydraulic control by using an intermediate valve with a mushroom-shaped intermediate valve member that enables separation and interchangeability of injection components corresponding to different fuels, such as gaseous or liquid fuels.

[0058] Many desirable alternative environmentally friendly and climate-neutral fuels tend to have inferior ignition characteristics, requiring relatively high ignition energy for clean combustion in piston internal combustion engines. This is particularly noticeable in combustion processes involving self-ignition and high compression, such as diesel processes, as is the case with most large engines. High compression leads to improved engine efficiency and thus reduced fuel consumption, which can result in significant operating cost savings in large engines that typically operate under heavy load for thousands of hours per year.

[0059] To ignite the alternative fuel during self-ignition, a small amount of high-pressure diesel fuel is typically injected. This can be optimally supplied by a micro-pilot injector, or by an injector that allows the engine to operate at full load on diesel fuel and provides a small ignition injection to ignite the alternative fuel only when high load is generated using the alternative fuel.

[0060] Therefore, the hydraulic control of the fuel injector disclosed herein can also be advantageously operated with diesel fuel. This allows for the advantageous elimination of a third control fuel.

[0061] The throttle passage is preferably formed in the intermediate valve member, particularly in the head of the intermediate valve member. However, the throttle passage can also be formed on the intermediate portion. In yet another modification, the throttle passage may be formed between the intermediate valve member and other components, for example, by a gap between the intermediate valve member and the intermediate portion. The throttle passage formed in the intermediate valve member can open into a blind hole formed in the intermediate valve member that belongs to the valve chamber on the opposite side of the control chamber. Preferably, the throttle passage is formed in the intermediate valve member adjacent to the control chamber. The throttle passage and the blind hole are preferably formed centrally with respect to the longitudinal axis. This allows the throttle passage to be formed to a desired length and the blind hole to form part of the valve chamber.

[0062] In one embodiment, the intermediate valve member opens the second connection between the control fluid inlet and the valve chamber when in the controlled open position of the intermediate valve member, and closes the second connection between the control fluid inlet and the valve chamber when in the controlled closed position of the intermediate valve member.

[0063] When the intermediate valve member is in the open position, the second connection between the control fluid inlet and the valve chamber is opened, so the valve chamber is filled with control fluid through the second connection, which allows for a faster opening of the intermediate valve member. In particular, the second connection can improve valve chamber filling compared to fuel injectors where, for example, the valve chamber is filled only from the control chamber via the throttle passage. Advantageously, even a slight opening of the intermediate valve member can fill the valve chamber through the second connection. With respect to the throttle passage, it may be sufficient for the flow of control fluid from the control chamber to the valve chamber to pass through the throttle passage and cause only a slight initial opening of the intermediate valve member, in which case the valve chamber is filled with a large amount of control fluid through the second connection. By blocking the second connection between the control fluid inlet and the valve chamber in the closed position of the intermediate valve member, disadvantages such as fuel loss and wear due to the relaxation of control fluid from the high-pressure chamber to the valve chamber during the injection process can be reduced or minimized, while opening the second connection allows for rapid filling of the valve chamber toward the opening of the intermediate valve member.

[0064] Embodiments of the present invention will be described in more detail with reference to the following drawings and accompanying description. [Brief explanation of the drawing]

[0065] [Figure 1] Figure 1 is a longitudinal cross-sectional view of an embodiment of a fuel injection valve. [Figure 2] Figure 2 is an enlarged view of a portion of the longitudinal section of Figure 1. [Figure 3] Figure 3 is another longitudinal cross-sectional view of the fuel injection valve shown in Figure 1, with the cross-sectional plane rotated 90° relative to that in Figure 1. [Figure 4] Figure 4 is an enlarged view of a portion of the longitudinal section of Figure 3. [Figure 5] Figure 5 is a further enlarged view of the intermediate valve portion in the region shown in Figure 4. [Figure 6] Figure 6 is a longitudinal cross-sectional view showing another embodiment of the fuel injection valve. [Modes for carrying out the invention]

[0066] In the description of the drawings, the same reference numerals are used for corresponding parts of each embodiment.

[0067] Figure 1 shows a longitudinal section view of an embodiment of the fuel injector 10.1. The housing 12 extends along the longitudinal axis L. The housing 12 comprises a fuel inlet 21 and a nozzle body 13 having an injection seat 131. The nozzle body 13 further has a centrally located injection opening 132 from which fuel is discharged for fuel injection into the combustion chamber of an internal combustion engine. The fuel chamber 22 extends within the housing 12 from the fuel inlet 21 to the injection seat 131. A cap 14 is positioned at the downstream end of the nozzle body 13, covering the central injection opening 132 of the nozzle body 13, and having a concentric opening 141. The cap 14 is positioned such that there is an axial gap between the cap 14 and the nozzle body 13.

[0068] The control piston 51 is positioned within the housing 12, adjustable along its longitudinal axis L. A control pressure spring 52 acts on the control piston 51, providing a closing force that acts toward the injection valve seat 131. The end of the control piston 51 opposite the injection valve seat 131 is guided within a guide sleeve 18, and one end of the control pressure spring 52 is supported by it.

[0069] The fuel injector 10.1 further has a hydraulic control device with an intermediate valve 53 for controlling the adjustment of the control piston 51.

[0070] The nozzle needle 61 is positioned on the nozzle body 13 at the end of the control piston 51 facing the injection valve seat 131. The nozzle needle 61 is in contact with the control piston 51 with the end face facing away from the injection valve seat 131, and as a result, the nozzle needle 61 is pressed against the end face of the control piston 51 facing the injection valve seat 131 by the injection pressure spring 62.

[0071] The housing 12 further includes an actuator receptor 16 that houses an electromagnetically actuated actuator device 43. An intermediate body 15 is positioned adjacent to the actuator receptor 16, and a control pressure spring 52 and a portion of the control piston 51 are located therein. The nozzle body 13 is joined to the downstream end face of the intermediate body 15, and the intermediate body 15 and the nozzle body 13 are detachably fixed to the actuator receptor 16 by a cap nut 17. Therefore, the nozzle body 13 and the nozzle needle 61 can be replaced by loosening the cap nut 17. A low-pressure control fluid return 42 is also located inside the housing 12, and its function will be further explained in relation to Figure 5, which will be described later.

[0072] Figure 2 is an enlarged view of the longitudinal cross-section of Figure 1. The intermediate body 15 is provided with a central guide hole 151, and the adjustment portion 512 of the control piston 51 is guided in a sliding fit within this hole at the end facing the injection valve seat 131. The control pressure spring 52, which exerts a closing force on the control piston 51 toward the injection valve seat 131, has its lower end supported by the shoulder portion 511 of the control piston 51 and its upper end supported by the guide sleeve 18. The guide portion 514 of the control piston 51 is guided into the guide sleeve 18 by sliding fit.

[0073] The downstream end face 513 of the control piston 51 and the upstream end face 611 of the nozzle needle 61 are in contact with each other, so that the injection pressure spring 62 that presses the nozzle needle 61 against the control piston 51 has its lower end resting on the shoulder 134 of the nozzle body 13 and its upper end resting on the 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. However, in certain embodiments, the upstream end face of the nozzle needle may have a smaller area than the downstream end face of the control piston. Because the nozzle needle 61 and the control piston 51 are designed separately, and the end faces 611 and 513 are designed separately, there is a tolerance for the radial orientation of the nozzle needle 61 and the control piston 51 relative to each other. In particular, the nozzle needle 61 and the nozzle body 13 do not require precise alignment with the guide hole 151 of the intermediate body 15, as is required, for example, in an integrated control injection piston. This simplifies the replacement of the nozzle needle 61 and the nozzle body 13.

[0074] The nozzle needle 61 is guided within the needle guide portion 133 of the nozzle body 13 and has a plurality of recesses 613 that extend along the longitudinal axis L of the nozzle needle 61 and open radially outward. This allows the fuel to flow around the nozzle needle 61 along the longitudinal axis L.

[0075] The intermediate valve 53 has a mushroom-shaped intermediate valve member 54 and is designed to move the control piston 51 along its longitudinal axis. This allows the control piston 51 to move the nozzle needle along its longitudinal axis.

[0076] Figure 3 shows another longitudinal section of the fuel injector 10.1 of Figure 1. This section is rotated 90° around the longitudinal axis L compared to Figure 1. The housing 12 is provided with a control fluid inlet 31 and a high-pressure control chamber 32 connected thereto. Part of the high-pressure control chamber 32 is located within the intermediate body 15, and the other part is located within the actuator acceptor 16.

[0077] For gaseous fuels such as hydrogen and methane, the gas injection pressure is usually relatively low. For example, the gas injection pressure for hydrogen is in the range of approximately 1 to 6 MPa (10 to 60 bar), and in certain cases it can reach approximately 10 MPa (100 bar). In the case of methane, the gas injection pressure is also in this range, and in certain cases it can reach approximately 10 MPa (100 bar) or more, and in even more specific cases it can reach approximately 25 MPa (250 bar). In this case, the control fluid pressure in the high-pressure control chamber is usually about 7 to 20 MPa (70 to 200 bar) higher than the gas injection pressure.

[0078] For liquid fuels, such as methanol and its derivatives (dimethyl ether (DME) or oxymethylene ether (OME)), or ammonia and diesel fuels, fuel injection pressure is typically relatively high. For example, the fuel injection pressure for methanol and its derivatives (dimethyl ether (DME) or oxymethylene ether (OME)) is approximately 40-60 MPa (400-600 bar), and in some cases can reach approximately 110 MPa (1100 bar). The control fluid pressure in the high-pressure control chamber is typically about 10-30 MPa (100-300 bar) higher than the fuel injection pressure. In the case of ammonia, the fuel injection pressure is typically above approximately 100 MPa (1000 bar), and in certain cases can reach 130 MPa (1300 bar). Similar to diesel, fuel injection pressure varies with engine load and engine speed, and in certain cases can fall below approximately 100 MPa (1000 bar). The control fluid pressure in the high-pressure control chamber is typically 10-20% higher than the fuel injection pressure. Therefore, the control fluid pressure in the high-pressure control chamber may be similar when using ammonia and when using diesel.

[0079] The housing 12 is provided with a leak discharge passage 72, which discharges leaks generated in the guide hole 151 to the leak outlet 73. The leak discharge passage 72 is also shown again in the enlarged view of Figure 4. The guide hole 151 of the intermediate body 15 is provided with a circumferential annular space 71, and the leak discharge passage 72 extends from this space to the leak outlet 73 (see Figure 3). This allows for the discharge of leaks that occur even when the adjustment part 512 of the control piston 51 is in a sliding fit state passing through the guide hole 151, thereby ensuring or improving fluid separation between the high-pressure control chamber 32 and the fuel chamber 22.

[0080] In certain embodiments, the leak drain channel 72 may have a check valve (not shown) designed to operate at an opening pressure between the control fluid inlet pressure of the high-pressure control chamber 32 and the fuel chamber pressure of the fuel chamber 22. This opening pressure is preferably closer to the fuel chamber pressure than to the control fluid inlet pressure.

[0081] In certain embodiments, for gaseous fuels such as hydrogen and methane, the fuel chamber pressure is relatively low, allowing for a combination of low-pressure control fluid return and leak discharge. In this case, the low-pressure control fluid return and leak discharge can share a common control fluid outlet. In this configuration, the low-pressure control fluid return pressure is identical to the leak drain return pressure, which corresponds to the opening pressure of the check valve. Such a design has the advantage of eliminating one outlet.

[0082] The intermediate body 15 has a lateral wall 152 that axially separates the high-pressure control chamber 32. The lateral wall 152 also provides spatial separation between the high-pressure control chamber 32 and the fuel chamber 22. The lateral wall 152 of the intermediate body 15 and the adjustment portion of the control piston 51, which is guided by sliding fitting within the guide hole 151, achieve fluid separation between the high-pressure control chamber 32 and the fuel chamber 22.

[0083] Figure 5 shows a further enlarged view of the portion of Figure 4 in the area of ​​the intermediate valve 53. The intermediate valve 53 comprises a mushroom-shaped intermediate valve member 54 having a head 541 and a shaft 542. The shaft 542 is guided into a guide recess in the intermediate portion 56. The guide sleeve 18 and the control piston guide portion 514 define the control chamber 55 together with the intermediate portion 56. The intermediate valve 53 has an intermediate valve seat formed on the head 541 side of the intermediate portion 56, which is designed to engage tightly with the head 541. The intermediate valve member 54 is axially movable between a control open position and a control closed position. In the control open position, the first connection between the control fluid inlet 321, which is connected to the high-pressure control chamber 32, and the control chamber 55 is opened. In the control closed position, the first connection between the control fluid inlet 321 and the control chamber 55 is closed. Furthermore, in the control closed position, the control chamber 55 is separated from the valve chamber 44 except for the throttle passage 544. The valve chamber 44 is connected to or disconnected from the low-pressure control fluid return 42 by raising or lowering the tappet 431 of the electromagnetically actuated actuator device 43 shown in Figure 1. The intermediate valve member 54 is connected to the valve chamber 44 and also has an internal bore 543 adjacent to the throttle passage 544.

[0084] The design of the intermediate valve 53 essentially corresponds to embodiments shown in International Publication No. 2016 / 041739, International Publication No. 2020 / 260285, or International Publication No. 2021 / 165275, the contents of which are incorporated herein by reference.

[0085] However, the intermediate valve 53 may also be equipped with other known hydraulic control devices, such as those shown in International Publication No. 2021 / 110663 or European Patent No. 0753658, the details of which are incorporated herein by reference.

[0086] Figure 6 shows a longitudinal section view of another embodiment of the fuel injector 10.2. The housing 12 has a nozzle body 13, an intermediate body 15, and an actuator mounting body 16, the nozzle body 13 and the intermediate body 15 being detachably secured to the mounting body 16 by a cap nut 17. The nozzle needle 61 is guided in the downstream region of the needle guide portion 133 of the nozzle body 13 and has a plurality of longitudinally extending recesses that open radially outward.

[0087] In contrast to the fuel injectors shown in Figures 1-5, the nozzle body 13 is provided with a guide hole 135, and both the adjustment portion 614 of the nozzle needle 61 and the adjustment portion 512 of the control piston 51 are guided by sliding fitting within this guide hole 135. Because the adjustment portion 614 of the nozzle needle 61 is guided within the guide hole 135, embodiments are also possible in which the nozzle needle 61 is not guided within the portion 133 of the nozzle body 13. In these embodiments, a gap is created between the nozzle needle 61 and the lower part 133 of the nozzle body 13 through which fuel can flow.

[0088] Between the control piston 51 and the nozzle needle 61, an adjustment chamber 136 is provided within the nozzle body 13. This adjustment chamber is surrounded radially by the nozzle body 13 and axially by the control piston 51 and the nozzle needle 61, and is fluidly closed. An annular space 71 is provided in the guide hole 135, and, as in the embodiments of Figures 3 and 4, a leak discharge passage extends from this annular space 71 to a leak outlet (not shown in Figure 6), allowing leakage generated within the guide hole 135 to be discharged.

[0089] As an alternative to the annular space 71, the leak can also be discharged from the adjustment chamber 136, in which case the annular space 71 can be omitted.

[0090] During injector assembly, slight misalignment of, for example, a few hundredths of a millimeter may occur between the nozzle body 13, the intermediate body 15, and the actuator receptor 16. Because the adjustment portion 512 of the integrated control piston 51 is guided by a tight sliding fit within the nozzle body 13, and the guide sleeve 18 for the control piston 51 is located within the actuator receptor 16, the guide sleeve 18 of the control piston 51 is not tightly guided in the radial direction. As shown in Figure 6, the guide sleeve 18 has radial play relative to the actuator receptor 16.

[0091] The high-pressure control chamber 32 is axially restricted by the end face of the nozzle body 13 adjacent to the intermediate body 15. The adjustment sections 512 and 614 of the control piston 51 and the nozzle needle 61, which are guided by sliding fitting into the guide hole 135, achieve fluid separation between the high-pressure control chamber 32 and the fuel chamber 22.

[0092] The nozzle needle 61 works in cooperation with the injection valve seat 131 of the nozzle body 13 to inject fuel into the combustion chamber of the internal combustion engine. For this purpose, the nozzle body 13 downstream of the injection valve seat 131 is provided with a plurality of eccentrically arranged injection holes 132. The arrangement of injection holes 132 shown in Figure 6 is typically advantageous for liquid fuels.

[0093] The fuel injector 10.1 shown in Figures 1-5 is particularly advantageous for gaseous fuels, while the fuel injector 10.2 shown in Figure 6 can be used particularly for liquid fuels. The nozzle body 13 and nozzle needle 61 are interchangeable between fuel injectors 10.1 and 10.2 depending on the requirements of the fuel used. On the other hand, hydraulic control using the intermediate valve 53 can be maintained regardless of the fuel used.

[0094] Many alternative environmentally friendly and climate-neutral fuels generally have inferior ignition characteristics and may require relatively high ignition energy for clean combustion in internal combustion engines. This is particularly noticeable in combustion processes that involve self-ignition and high compression, such as diesel processes, as is the case with most large engines. High compression leads to improved engine efficiency and thus reduced fuel consumption, which can result in significant operating cost savings for large engines that typically operate under heavy load for thousands of hours per year.

[0095] To ignite the alternative fuel during self-ignition, a small amount of high-pressure diesel fuel is typically injected. This can be optimally supplied by a micro-pilot injector, or by an injector that allows the engine to operate at full load on diesel fuel and only injects a small amount of alternative fuel to ignite it when high load occurs.

[0096] Therefore, the hydraulic control disclosed herein for the fuel injectors shown in Figures 1-6 can also be advantageously operated with diesel fuel. This makes it advantageous to omit a third separate control fuel.

Claims

1. A fuel injector (10.1, 10.2) that intermittently injects fuel into the combustion chamber of an internal combustion engine, A nozzle body (13) having a control fluid inlet (31), a fuel inlet (21), and an injection valve seat (131) is provided, and a housing (12) extending along the longitudinal axis (L) is provided. A high-pressure control chamber (32) is located inside the housing and connected to the control fluid inlet, A fuel chamber (22) is located within the housing and extends from the fuel inlet to the injection valve seat, A control piston (51) is located within the housing and is adjustable along its longitudinal axis, and a control pressure spring (52) acts on the control piston, which exerts a closing force toward the injection valve seat, A hydraulic control device (53) for controlling the adjustment of a control piston along the longitudinal axis, It includes a nozzle needle (61) positioned at the end of a control piston facing the injection valve seat, at least a portion of which is located within the nozzle body and configured to cooperate with the injection valve seat to inject fuel into the combustion chamber of an internal combustion engine, The nozzle needle is movable by adjusting the control piston along the longitudinal axis of the fuel injector (10.1, 10.2).

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

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

4. The fuel injector according to claim 3 (10.1, 10.2), characterized in that the nozzle body (13) or intermediate body (15) has guide holes (151, 135), and within the guide holes, an adjustment portion (512) of a control piston (51) positioned at the end facing the injection valve seat (13) is guided by sliding fitting, and / or within the guide holes, an adjustment portion (614) of a nozzle needle (61) positioned away from the injection valve seat is guided by sliding fitting.

5. The fuel injector according to claim 4 (10.1, 10.2), characterized in that the guide holes (151, 135) have a circumferential annular space (71), and the fuel injector has a leak outlet (73) and a leak drainage channel (72) extending from the annular space to the leak outlet.

6. The fuel injection valve according to claim 5, wherein the leak drain channel has a check valve designed to open at an opening pressure between the control fluid inlet pressure and the fuel chamber pressure, and the opening pressure is preferably closer to the fuel chamber pressure than the control fluid inlet pressure.

7. The fuel injection valve according to claim 6, characterized in that the valve opening pressure is lower than 10% or about 10% higher than the fuel chamber pressure.

8. The fuel injection valve according to claim 6 or 7, characterized in that the check valve is located within the housing.

9. The fuel injection valve according to claim 6 or 7, characterized in that the check valve is located on the outside of the housing.

10. A fuel injector according to any one of claims 1 to 9, characterized in that an injection pressure spring (62) is disposed inside the nozzle body (13), and the spring presses the nozzle needle (61) against the control piston (51).

11. A fuel injector according to any one of claims 1 to 10 (10.2), characterized in that a fluidly closed adjustment chamber (136) is disposed between a control piston (51) and a nozzle needle (61), the adjustment chamber being defined radially by the nozzle body (13) or an intermediate, and axially by the control piston (51) and the nozzle needle (61).

12. The fuel injector according to any one of claims 1 to 11 (10.1, 10.2), characterized in that the fuel injector has an actuator receptor (16), the nozzle body (13) is preferably detachably fixed by a cap nut (17), and the nozzle body and nozzle needle (61) are replaceable.

13. The fuel injector according to any one of claims 1 to 12 (10.1, 10.2), wherein the nozzle needle (61) is guided within a needle guide portion (133) of the nozzle body (13), and the nozzle needle preferably has at least one recess (631) that extends longitudinally and opens radially outward.

14. The fuel injection valve according to any one of claims 1 to 13, characterized in that the nozzle body (13) has a concentric injection opening (132).

15. The fuel injector according to any one of claims 1 to 13, characterized in that the nozzle body has a plurality of eccentrically arranged injection openings (132).

16. A fuel injector according to any one of claims 1 to 15 (10.1), characterized in that a cap (14) is positioned at the downstream end of the nozzle body (13), the cap covering at least one injection opening (132) and having a concentric or at least one eccentric opening (141).

17. The fuel injection valve (10.1) according to any one of claims 1 to 16, characterized in that the fuel chamber (22) has a fuel supply section having a diameter larger than the diameter of the control fluid supply section of the high-pressure control chamber (32).

18. A fuel injector according to any one of claims 1 to 17, characterized in that the hydraulic control device (53) is configured to move a control piston (51) along a longitudinal axis (L) by changing the pressure in a control chamber (55), the hydraulic control device includes an intermediate valve (53) having an intermediate valve member (54), the intermediate valve member opening a first connection between a control fluid inlet (321) connected to a high-pressure control chamber (32) and the control chamber (55) in a controlled open position, and closing the first connection between the control fluid inlet and the control chamber in a controlled closed position, separating the control chamber from the valve chamber (44) except for a throttle passage (544), and the fuel injector includes an electromagnetically actuated actuator device (43) for connecting the valve chamber to a low-pressure control fluid return (42) and separating the valve chamber from the low-pressure control fluid return.

19. The fuel injector according to 18 (10.1, 10.2), characterized in that the control piston (51) has a guide portion (514) at an end away from the injection valve seat (131), the guide portion is guided by sliding fitting within a guide sleeve (18), the fuel injector has an intermediate portion (56) which together with the guide sleeve and the control piston defines a control chamber (55), the intermediate valve member (54) is mushroom-shaped and has a shaft portion (542) guided into a guide recess of the intermediate portion and a head portion (541), and the intermediate valve (53) is formed on the side facing the head portion of the intermediate portion and has an intermediate valve seat that cooperates with the head portion.

20. The fuel injection valve according to claim 19, characterized in that the intermediate valve member opens a second connection between the control fluid inlet and the valve chamber when the intermediate valve member is in a controlled open position, and closes the second connection between the control fluid inlet and the valve chamber when the intermediate valve member is in a controlled closed position.

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