JP2018003839A - Nozzle head for large-sized diesel engine fuel injection nozzle and process of manufacture of the nozzle head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a nozzle head for a fuel injection nozzle of a large-sized diesel engine, in particular a two-stroke large-sized diesel engine that is scavenged in a longitudinal direction.SOLUTION: This invention relates to a longitudinal channel (2) extending from an upper end part (21) to a lower end part (22) in an axial line direction (A), the longitudinal channel (2) enables fuel to be fed and supplied to the longitudinal channel (2) itself and this invention relates to at least one of nozzle channels (4) extending from the longitudinal channel (2) to each of nozzle openings (3). At least one of the nozzle channels (4) enables fuel to be fed to a combustion chamber of a large-sized diesel engine through the nozzle channels (4) themselves. Each of the nozzle channels (4) has a smaller flow section than that of the longitudinal channel (2) itself. The lower end part (22) of the longitudinal channel (2) is arranged above each of the nozzle openings (3) with respect to the axial line direction (A) and with respect to a normal operating position.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a nozzle head for a fuel injection nozzle of a large diesel engine, particularly a two-stroke large diesel engine that is scavenged in the longitudinal direction, and a method for manufacturing the nozzle head. is there.

  Large diesel engines, such as two-stroke large diesel engines that are scavenged in the longitudinal direction, are often used as power sources for ships and in fixed operations, for example, for driving large generators that generate electrical power. Here, in principle, such an engine is operated continuously for a considerably long time, and there are severe requirements regarding safety and availability during operation. For this reason, long repair intervals, low wear, and economical use of operating materials are key criteria for the driver.

  A fundamental point that has gained in importance over the past few years is the quality of exhaust gas, particularly the concentration of nitrogen oxides contained in the exhaust gas. For this reason, particularly with respect to a two-stroke large diesel engine, not only the combustion of conventional heavy oil mixed with a large amount of pollutants but also the combustion of diesel oil and other fuels is increasingly regarded as a problem. Compliance with emissions regulations is becoming increasingly difficult, technically more complex and thus more expensive, or ultimately such compliance is even less economically wise Because.

  In fact, there is a need for a so-called “dual fuel engine” for that purpose. This is an engine that can be operated with two different fuels. In the gas mode, gas such as natural gas such as LNG (liquefied natural gas), gas in the form of liquefied petroleum gas, or gas suitable for operating an internal combustion engine is used for combustion, while in liquid mode, A suitable liquid fuel such as diesel oil or heavy oil can be burned in the same engine.

  Within the scope of this application, the term “large diesel engine” refers not only to diesel operation characterized by fuel self-ignition, but also to large engines that can be operated in Otto operation characterized by external fuel ignition, and these two operations. Large engine that can be operated in a mixed form. Furthermore, the term large diesel engine includes in particular the above-mentioned dual fuel engine and large engines that use fuel self-ignition for external ignition of other fuels.

  In liquid mode, fuel is usually introduced directly into the combustion chamber of the cylinder and burned according to the principle of self-ignition. In the gas mode, it is well known to mix gas in a gaseous state with scavenging air in accordance with the Otto principle to produce an ignitable mixture in the combustion chamber of the cylinder. In this low pressure or high pressure process, a small amount of liquid fuel is injected into the combustion chamber of the cylinder or into the precombustion chamber at the appropriate time, which fuel causes the air / gas mixture to ignite, so that the mixture is usually cylinder It is ignited within. During operation, the dual fuel engine can be switched from gas mode to liquid mode or vice versa.

  When a large diesel engine is operated with liquid fuel such as heavy oil or diesel oil, the introduction of fuel into the combustion chamber of the cylinder is usually realized by using a fuel injection nozzle having a nozzle body and a nozzle head. The nozzle head is also referred to as an atomizer. In principle, the nozzle head is provided with a plurality of nozzle openings for injecting fuel into the combustion chamber. To start or end the injection process, the fuel injection nozzle is provided with a movable nozzle needle that interacts with the valve seat to open and close the passage to the nozzle opening.

  Nozzle heads are usually wear parts that are exposed to high thermal, mechanical and chemical stresses. The mechanical stress is above all due to the high injection pressure which can exceed 1000 bar. The thermal stress is caused by an extreme temperature change between the high temperature or combustion temperature in the combustion chamber and the temperature of the newly supplied scavenging air. Chemical stress is mainly due to high temperature corrosion and hot corrosion.

  For these reasons, and especially due to thermal stress, the valve seat is usually placed at a predetermined distance from the nozzle opening to avoid excessive intake flow of combustion heat. A longitudinal bore designed as a blind hole is provided downstream of the valve seat of the nozzle head, from which the bore diverges into the nozzle opening.

There is one problem with the spatial distance between the valve seat and the nozzle opening. At the end of fuel injection, the nozzle needle is pressed into the valve seat such that fuel downstream of the valve seat in the blind hole (ie, between the valve seat and the nozzle hole) is disconnected from the delivery pressure. This part of the fuel can become undesirable deposits on the nozzle head, and after the injection has ended, it is atomized in a bad way and enters the combustion chamber through the nozzle opening or drops into the combustion chamber. There may be little or no combustion there. This increase and the fuel consumption, in particular an increase in pollutant emissions of the exhaust gas containing nitrogen oxides NO _x, as well, leading to unburned fuel adhering in all parts of the component for circulating combustion chamber and the exhaust gas .

  Various proposals have already been made to solve these problems. For example, it is well known to provide a locking element on the nozzle needle downstream of the valve seat that prevents fuel from flowing through the nozzle opening immediately after the nozzle needle is pressed into the valve seat. However, even if such a configuration is known to be effective, technical equipment is expensive, leading to high costs.

  Based on this prior art, the object of the present invention is a nozzle head that is as simple as possible for the fuel injection nozzle of a large diesel engine, which is caused by the fuel remaining downstream of the valve seat after the end of injection. It is to provide a nozzle head that helps to at least significantly reduce the problem. Another object of the present invention is to provide a method for manufacturing the nozzle head.

  The present invention solving these problems is characterized by the structure of the independent claims of each category.

According to the present invention, a nozzle head for a fuel injection nozzle of a large diesel engine, particularly a two-stroke large diesel engine scavenged in the longitudinal direction,
A longitudinal channel extending axially from the upper end to the lower end, the longitudinal channel being adapted to allow fuel to be delivered to the longitudinal channel;
At least one nozzle channel extending from the longitudinal channel to the nozzle opening, through which the fuel can be introduced into the combustion chamber of a large diesel engine. Each nozzle channel has a flow cross-sectional area that is smaller than the flow cross-sectional area of the longitudinal channel, and the lower end of the longitudinal channel is above each nozzle opening with respect to the axial direction and with respect to the normal operating position. A nozzle head is provided.

  In this nozzle head design, the longitudinal channel does not extend over the entire length of the nozzle head in the axial direction and terminates above each nozzle opening, so that the valve seat and nozzle opening Can be significantly reduced compared to known nozzle heads. This, together with the smaller flow cross-sectional area of the at least one nozzle channel, is combined with the valve in the nozzle head after the end of the injection process, i.e. when the nozzle needle comes into contact again to seal the valve seat. The amount of fuel remaining downstream of the seat can be basically reduced. As a result, only a very small amount of fuel will remain downstream of the valve seat in the nozzle head after the injection process has been completed, resulting in adverse effects caused by this fuel, particularly pollutant emissions, fuel consumption, and harmful adhesion. It can be greatly reduced. This nozzle head is also particularly simple in design, since it is not necessary to employ costly techniques for the technical equipment.

  According to the present invention, there is provided a method for manufacturing a nozzle head according to the present invention, wherein the nozzle head is manufactured using an additional processing method.

  Additive processing or additive manufacturing, also referred to as production manufacturing, is understood to mean a processing method of adding material. In the additive manufacturing method, a material having no shape such as liquid or powder or a material having a general shape such as a strip shape material or a wire shape material is usually physically and / or chemically processed, for example, A desired structure is produced by building on a substrate. Examples of known additive processing methods for metal materials include, for example, hardfacing processes, especially tungsten / inert gas welding (WIG), laser cladding, plasma methods, selective laser melting (SLM), laser sintering, etc. There is an inert gas process.

  Compared to the removal process or removal manufacturing method, where material is removed from the workpiece or blank, the additive process method has at least practically no geometric constraints and therefore has any structural member, especially internal cavitation. A member can be manufactured. For removal manufacturing, for example, all that is generally understood conventionally to mean manufacturing characterized by removing excess material from a workpiece or blank in the form of chips to obtain the desired geometry. Includes machining manufacturing types. Machining manufacturing includes, for example, milling and turning, drilling, planing, file finishing, grinding, honing, and lapping, to name a few examples.

  When the nozzle head is manufactured using an additional processing method according to the present invention, its overall geometric design is practically unconstrained.

  According to one embodiment, the entire nozzle head is manufactured using an additional processing method. That is, the entire nozzle head is constructed in a generative manner.

  According to a preferred embodiment, an insert in which all the nozzle channels are arranged is manufactured using an additive process, and the insert extends in the longitudinal bore of the nozzle head extending in the axial direction and comprising a longitudinal channel. insert.

  With respect to this embodiment, the insert abuts against the wall where the entire outer interface of the insert defines a longitudinal bore. That is, it is preferred that the insert is designed to completely fill the longitudinal bore with respect to the radial direction. When the insert is inserted into the longitudinal bore, the outer diameter basically corresponds to the inner diameter of the longitudinal bore so that the outer boundary surface of the insert is in radial contact with the wall defining the longitudinal bore. It preferably has a cylindrical shape.

  Each nozzle channel is designed as an inner channel that is located entirely within the insert. That is, each nozzle channel is completely surrounded by the insert so that only the insert defines each nozzle channel. This approach avoids that other parts, such as the walls defining the longitudinal bore, form the boundary of the nozzle channel.

  This embodiment not only allows the nozzle channel to be manufactured in virtually any shape, but also inserts with nozzle channels into the longitudinal bores or blind holes of known conventional nozzle heads. The nozzle head according to the above can be realized. For this reason, in particular, the existing conventional nozzle head can be transformed into the nozzle head according to the present invention by this specific example. For this purpose, it may be necessary to enlarge this longitudinal bore or blind hole so that an additional manufactured insert with a nozzle channel can be inserted into the longitudinal bore of a conventional nozzle head.

  The insert may be manufactured so that its entire circumference contacts the inner wall of the longitudinal bore and fuel flows from the longitudinal channel essentially only through one or more nozzle channels to the combustion chamber. preferable.

  The additive processing method has the advantage that one or more nozzle channels can be produced in any shape, as already mentioned. Thus, each nozzle channel can be freely manufactured in any form and optimized for each application. This helps at least suppress cavitation and realize an optimal fuel flow without disturbance. It is also possible to at least greatly suppress adhesion in the nozzle head.

  There are additional advantages to the design using inserts. That is, the insert can be made of a different material than the rest of the nozzle head. The insert is not exposed to extremely harsh environmental conditions in the combustion chamber, so the rest of the nozzle head is cost-effective while choosing other materials that have a proven track record in the combustion chamber and are particularly advantageous. It can be made from a material selected in consideration of aspects such as conversion and good fuel flow.

  With regard to technical equipment, it is preferred that the nozzle head comprises a plurality of nozzle channels, each nozzle channel extending from the longitudinal channel to the channel opening so that fuel can be introduced into the combustion chamber of a large diesel engine. . According to this method, it is possible to ensure that the fuel is particularly suitably distributed in the combustion chamber of the cylinder.

  According to a preferred design, the nozzle head has an axially extending longitudinal bore, the longitudinal bore includes a longitudinal channel, and an insert in which all the nozzle channels are arranged is provided in the longitudinal bore. . As already explained with respect to the method according to the invention, this design has several advantages. An insert comprising at least one nozzle channel is inserted into the longitudinal bore of the nozzle head, the upper part of the longitudinal bore of the nozzle head with respect to the normal operating position forming a longitudinal channel, downstream of which the fuel is longitudinal. An insert having at least one nozzle channel that can flow from the directional channel to the combustion chamber follows.

  Therefore, for the reasons described above, it is preferred that the insert be made from a material other than that used for the remainder of the nozzle head. The wall of the nozzle head is provided with one or more bores that form nozzle openings through which fuel can flow from each nozzle channel into the combustion chamber.

  For the best possible fuel distribution within the combustion chamber, each nozzle channel is preferably designed such that fuel can be discharged from each nozzle opening at an injection angle that is inclined relative to the axial direction. Preferably, each injection angle is smaller than 90 °, and more preferably smaller than 80 °. The injection angle is understood to mean the smaller of the two angles enclosed by the surface normal of the nozzle opening and the axial direction.

  In order to ensure optimal fuel injection, it is preferred to provide at least two nozzle channels with different injection angles.

  A further preferred approach is to design each nozzle channel so that it leads axially to the longitudinal channel. This approach helps minimize fuel flow resistance during flow from the longitudinal channel to each nozzle channel, with each nozzle channel extending in the same direction as the longitudinal channel in the vicinity of the longitudinal channel. . As a result, it is not necessary to divert fuel when flowing from the longitudinal channel to the nozzle channel. According to this method, in particular, the influence of deterioration due to erosion can be avoided.

  Depending on the application, it may also be advantageous to design the at least one nozzle channel so as to extend or taper in a region adjacent to the nozzle opening. According to this method, the fuel flow behavior can be optimized.

  It is particularly advantageous to design each nozzle channel without edges or corners. This can at least greatly reduce adhesion, erosion, and cavitation that usually occur gradually at sharp edges and corners and lead to high levels of wear.

  A further preferred design is to design at least one nozzle channel in an arch or curved shape. According to the arched design or curved design, the fuel flow can be transferred from the axial direction to the desired injection direction, advantageously without loss.

  Advantageously, at least two nozzle channels having a curved region are provided, and the curvature of the curved regions of both nozzle channels is different. This design makes it possible in particular to achieve different fuel injection angles and at least greatly reduce signs of wear caused by cavitation and erosion.

  According to the present invention, there is provided a large diesel engine having a fuel injection nozzle with a nozzle head designed according to the present invention or manufactured according to the method according to the present invention, in particular a two-stroke large diesel engine scavenged in the longitudinal direction. Proposed.

  Advantageous approaches and designs of the invention are described in the dependent claims.

  Hereinafter, the present invention will be described based on specific examples with reference to the following drawings.

Fig. 3 is a longitudinal section of a fuel injection nozzle of a prior art large diesel engine. FIG. 2 is a schematic longitudinal sectional view of a nozzle head of the fuel injection nozzle from FIG. 1. FIG. 3 is a schematic longitudinal sectional view of a specific example of a nozzle head according to the present invention.

  Within the scope of the present invention, the definition of relative positions such as “down”, “up”, “down”, “up” etc. is in each case understood with reference to the normal operating position. .

  To better understand the present invention, the structure of a fuel injection nozzle of a large diesel engine known in the prior art will be described first with reference to FIG. In order to make it easier to distinguish the prior art from the present invention, the devices known in the prior art use symbols with apostrophes.

  FIG. 1 shows a longitudinal section of a prior art fuel injection nozzle of a large diesel engine, generally designated 10 '. In particular, this is the fuel injection nozzle 10 'of a two-stroke large diesel engine that is scavenged in the longitudinal direction. This nozzle allows liquid fuel, in particular heavy oil or diesel oil, to be introduced into the combustion chamber 20 'of a large diesel engine cylinder.

  This known fuel injection nozzle 10 'includes a nozzle body 11', and a nozzle head 1 'is connected to the nozzle body 11'. This connection is realized by the holding sleeve 12 '. The holding sleeve 12 'is tapered at the lower end in the drawing toward the longitudinal axis of the fuel injection nozzle 10'. The axial direction A 'is defined by the longitudinal axis of the fuel injection nozzle 10', but it is also the longitudinal axis of the nozzle head 1 '. The holding sleeve 12 'is fixed to the nozzle body 11' by an union nut 13 'and an elastic element 14' such as a snap ring. The nozzle head 1 'supports itself against the tapered portion of the holding sleeve 12'.

  For better understanding, FIG. 2 shows a schematic longitudinal cross-sectional view of the nozzle head 1 ′ of the fuel injection nozzle 10 ′ of FIG. 1.

  The nozzle head 1 'has a longitudinal bore 5' and has at least one nozzle opening 3 'in the region of its lower end. Nozzle openings 3 'are usually provided in some, for example five, and communicate with the longitudinal bore 5' so that fuel can escape from the nozzle openings 3 'to the combustion chamber 20'.

  Inside the nozzle body 11 ′, a pressure chamber 14 ′ in which fuel is supplied from a supply pipe 15 ′ is provided. High pressure fuel can be delivered to the fuel injection nozzle 10 'via a delivery pipe 15' from a storage reservoir, usually a common rail system accumulator. The pressure chamber 14 'is limited in the axial direction A' by the valve seat 16 '. Further, a nozzle needle 17 ′ that basically extends in the axial direction A ′ and acts on the valve seat 16 ′ is disposed inside the nozzle body 11 ′. In the locking position shown in FIG. 1, the lower tip of the nozzle needle 17 'is pushed into the valve seat 16' and the passage from the pressure chamber 14 'to the downstream longitudinal bore 5' is closed. The nozzle needle 17 'receives a spring load from a compression spring (not shown) and receives a preload on the valve seat 16'. As shown in the drawing, in the open position of the nozzle needle 17 ′, the nozzle needle 17 ′ is lifted upward from the valve seat 16 ′, and fuel is placed between the lower end of the nozzle needle 17 ′ and the valve seat 16 ′. It forms an open passage which can be moved from the pressure chamber 14 'into the longitudinal bore 5'.

  The volume of the longitudinal bore 5 'downstream of the valve seat 16' is typically designated as a blind hole or a blind hole volume.

  In the example described herein, the longitudinal bore 5 'is designed as a basically cylindrical bore extending in the axial direction A' and having a length L '(see FIG. 2). The diameter D 'of the longitudinal bore 5' defines a flow cross-sectional area that is understood to mean the cross-sectional area available for fuel flow in the longitudinal bore 5 '.

  The nozzle needle 17 'is disposed in the bore 18' of the nozzle body 11 'extending in the axial direction A'. For reasons of space saving, this bore is only partially represented in FIG. The bore 18 'has an inner diameter B' that is slightly larger than the outer diameter of the nozzle needle 17 'so that the nozzle needle 17' can be safely and accurately guided within the bore 18 '.

  In particular, as shown in the schematic diagram of FIG. 2, each nozzle opening 3 ′ is connected to a longitudinal bore 5 ′ of the nozzle head 1 ′ via a nozzle channel 53 ′ so that pressurized fuel is fed into the longitudinal bore 5. It is injected into the combustion chamber 20 'through the nozzle channel 53' and the nozzle opening 3 '. The flow cross-sectional area of each nozzle channel 53 'is very small compared to the flow cross-sectional area of the longitudinal bore 5' defined by the longitudinal bore diameter D ', in particular at least one fifth. Each of the nozzle channels 53 ′ normally extends with an inclination or an inclination with respect to the axial direction A ′, and the injection angle at which the fuel is inclined with respect to the axial direction A ′ from each nozzle opening 3 ′. It can be released with α ′. The injection angle α ′ is understood as meaning the smaller of the two angles formed by the surface normal of the nozzle opening 3 ′ and the axial direction. Of course, each injection angle α ′ can be different for different nozzle openings 3 ′.

  FIG. 3 is a schematic longitudinal sectional view showing a specific example of the nozzle head according to the present invention, and the whole is denoted by reference numeral 1. The nozzle head 1 is intended for a fuel injection nozzle of a large diesel engine, in particular a two-stroke large diesel engine that is scavenged in the longitudinal direction, as described with reference to FIG. Acts with the nozzle body.

  The nozzle head 1 comprises a longitudinal channel 2 extending in the axial direction A from the upper end 21 to the lower end 22 and having a length L1. The longitudinal channel 2 is preferably designed in a cylindrical shape with a diameter D. Similar to that shown in FIG. 1, the axial direction A is defined by the longitudinal axis of the nozzle head 1 which is identical to the longitudinal axis of the fuel injection nozzle when the nozzle head 1 is attached to the fuel injection nozzle. . As in the prior art, fuel introduced into the combustion chamber of the cylinder of the large diesel engine can be delivered to the longitudinal channel 2.

  Furthermore, the nozzle head 1 has at least one nozzle channel 4 that extends from the longitudinal channel 2 to a nozzle opening 3 through which fuel can be introduced into the combustion chamber of the cylinder. The nozzle head 1 usually comprises several separate nozzle openings 3 each connected to the longitudinal channel 2 via a nozzle channel 4. In the schematic diagram of FIG. 3, two nozzle openings 3 are shown, each fluidly connected to the longitudinal channel 2 via a nozzle channel 4.

  In this regard, each nozzle channel 4 has a flow cross-sectional area that is very small compared to the flow cross-sectional area of the longitudinal channel 2, for example, less than one fifth. The flow cross-sectional area is understood to mean each plane perpendicular to the main flow direction of the fuel.

  According to the invention, the lower end 22 of the longitudinal channel 2 is arranged axially above each nozzle opening 3 with respect to the normal operating position shown in FIG. By this means, the volume available for the fuel in the nozzle head can be greatly reduced, and only a very small amount of fuel can remain in the nozzle head 1 after the end of injection.

  The nozzle head 1 is manufactured using an additional processing method. These processing methods or manufacturing methods are also referred to as production methods or production production. Additive processing or additive manufacturing is understood to mean a processing method in which the corresponding member is constructed by material addition. In an additive manufacturing process, a material having no shape such as liquid or powder, or a material having a general shape such as a strip shape material or a wire shape material is usually physically and / or chemically processed. For example, a desired structure is formed by building on a substrate. Examples of known additive processing methods for metal materials include, for example, hardfacing processes, especially tungsten / inert gas welding (WIG), laser cladding, plasma methods, selective laser melting (SLM), laser sintering, etc. There is an inert gas process.

  Addition or generation manufacturing is particularly advantageous in that it can be manufactured with any form of internal cavitation, since it is not subject to any geometric constraints. With respect to the nozzle channels 4, this has a great advantage in that each nozzle channel 4 can be manufactured in virtually any shape. Thereby, for example, at least greatly suppressing cavitation, reducing deterioration caused by erosion as much as possible, preventing adhesion in the nozzle channel 4, optimizing fuel flow behavior, Each shape of the nozzle channel 4 can be optimized with respect to various aspects such as achieving optimal spraying or dispersion of the fuel.

  In the preferred embodiment shown in FIG. 3, an insert 6 is provided which is arranged in the longitudinal bore 5 of the nozzle head 1. The longitudinal bore 5 extends in the axial direction A over a length L that is greater than the length L 1 of the longitudinal channel 2 in the axial direction A. This insert 6 contains all the nozzle channels 4 and completely fills the lower end of the longitudinal bore 5 shown over the length L2. This means in particular that the insert 6 is in full contact with the inner wall of the longitudinal bore 5.

  Each nozzle channel 4 is designed as an inner channel completely located inside the insert 6. For this reason, each nozzle channel 4 is laterally defined by the insert 6 along the entire circumference of the channel 4. In particular, it should be understood that the nozzle channel 4 is not disposed on the surface of the insert 6, which is the surface that radially defines the insert 6, but is disposed inside the insert 6. Only the end of the nozzle channel 4 to the nozzle opening 3 and the opening at the other end to the longitudinal channel 2 are located on the surface of the insert 6.

  The insert 6 with the nozzle channel 4 is manufactured using an additional processing method.

  In order to manufacture the nozzle head 1, it is preferable to use a known nozzle head as shown in FIG. The wall 7 of the nozzle head 1 that defines the longitudinal bore 5 is provided with at least one bore that forms the nozzle opening 3. FIG. 3 shows two such nozzle openings 3. These nozzle openings 3 are preferably identical to the nozzle openings of the known nozzle head 1 'shown in FIG. The insert 6 is then introduced into the longitudinal bore 5 or into the longitudinal bore 5 'of the known nozzle head 1' until it contacts the lower end of the longitudinal bore 5 or 5 '. Thereby, the lower region of the longitudinal bore 5 or 5 ′ is preferably completely filled by the insert 6 over the entire length L2, and the upper part of the longitudinal bore 5 or 5 ′ has a length L1. A longitudinal channel 2 is formed. L1 and L2 complement each other to form the length L of the longitudinal bore 5.

  If a known nozzle head 1 'is used for the manufacture of the nozzle head 1, depending on the application, the original diameter D' (Fig. 2) of the longitudinal bore 5 'can be drilled or other suitable processing method. It may be advantageous to form a longitudinal bore 5 having a diameter D and subsequently inserting the insert 6.

  Once all the nozzle channels 4 discharge openings are arranged, the inserts 6 are positioned so that each of the inserts 6 coincides with one of the nozzle openings 3 in the wall 7 of the nozzle head 1 after positioning the insert 6 in the longitudinal bore 5. It is obvious that is manufactured.

  There are several advantages to the method of manufacturing the nozzle head 1 based on the known nozzle head 1 '. In particular, the design outside the nozzle head 1 is understood as meaning the arrangement and design of the nozzle openings 3, which can be used with known nozzle heads. Furthermore, the nozzle head 1 can be easily inserted into an existing fuel nozzle without any structural changes or modifications. Also, the existing nozzle 6 may be inserted into the longitudinal bore 5 'of the existing nozzle head 1' by increasing the diameter D 'of the original longitudinal bore 5'. It is possible to convert or improve the head to a nozzle head 1 according to the invention.

  A further advantage of the design using the insert 6 is that the insert 6 can be manufactured from a different material than other parts of the nozzle head 1, for example its wall 7. This makes it possible to use a material with a particularly suitable track record for the extremely severe conditions in the combustion chamber, such as a very large thermal stress, in the manufacture of the nozzle head 1 without the insert 6. Examples of known workpieces used for the production of the nozzle head 1 of a large diesel engine include steel, nickel-based or cobalt-based alloys such as stellite 6. These materials are particularly suitable for erosion, wear and cavitation in the nozzle openings 3.

  Since the insert 6 itself is protected by the wall 7 of the nozzle head 1 and is not exposed to the harsh conditions in the combustion chamber, another material, preferably a metal material, can be selected for manufacturing the insert 6. . As a result, a great deal of freedom is obtained with respect to the selection of the appropriate material used to construct the insert 6 of the nozzle head 1 using additive manufacturing. The material used for the insert 6 can be selected, for example, by considering aspects such as cost optimization and optimal fuel guidance.

  A particular advantage of the design of the nozzle head 1 according to the invention is that each flow connection between the longitudinal channel 2 and the nozzle opening 3, ie each nozzle channel 4, can be designed in any form. In other words, there is no particular shape restriction. This allows each nozzle channel 4 to be designed for optimal fuel flow behavior or optimal fuel guidance. Thereby, each nozzle channel 4 can also be optimized in particular with respect to cavitation, erosion and wear, and efficient introduction of fuel into the combustion chamber.

  In the following, some preferred techniques for designing each nozzle channel 4 and some of the modifications will be listed and described.

  Each nozzle channel 4 is preferably designed such that fuel can be discharged from each nozzle opening 3 at an injection angle α inclined with respect to the axial direction A. The injection angle α is understood to mean the smaller of the two angles enclosed by the surface normal of the nozzle opening 3 and the axial direction. Of course, each injection angle α can be different for different nozzle openings 3. Each injection angle α is preferably smaller than 90 °, particularly preferably smaller than 80 °. A particularly preferable range is 70 ° to 75 °.

  Although not essential, it is also advantageous to design each nozzle channel 4 so that it passes axially into the longitudinal channel 2 as shown in FIG. This makes it possible to achieve a particularly good flow of fuel from the longitudinal channel 2 to each nozzle channel 4.

  It is also advantageous to design the nozzle channel 4 so as to expand or taper, particularly in the region adjacent to the nozzle opening 3. This technique can improve fuel spray into the combustion chamber.

  As shown also in FIG. 3, it is particularly preferable to design each nozzle channel 4 so that there are no edges or corners. Because edges and corners are particularly susceptible to undesirable cavitation and erosion risks, it is preferable to avoid such edges and corners. Therefore, as shown in FIG. 3, it is advantageous if the nozzle channel 4 is designed to be arched or curved so that the direction of fuel can be changed in the most optimal manner possible from the axial direction A to the desired injection direction. .

In this regard, it is particularly advantageous to provide at least two nozzle channels 4 with curved areas and to make the curvature of the curved areas of both nozzle channels 4 different. This is illustrated in FIG. 3 by two arrows having the symbols r ₁ and r ₂ .

  According to another embodiment of the invention, the entire nozzle head is manufactured using an additional processing method. In this specific example, the insert 6 is not provided, and the entire nozzle head 1 is constructed using addition or production. Further, the above description is applied in the same meaning to a design without the insert 6.

Claims (15)

A nozzle head for a fuel injection nozzle of a large diesel engine, particularly a two-stroke large diesel engine scavenged in the longitudinal direction,
A longitudinal channel (2) extending in the axial direction (A) from the upper end (21) to the lower end (22), so that fuel can be delivered to the longitudinal channel (2). A longitudinal channel (2);
At least one nozzle channel (4) extending from the longitudinal channel (2) to the nozzle opening (3) so that fuel can be introduced into the combustion chamber of a large diesel engine through the nozzle channel (4). At least one nozzle channel (4), each nozzle channel (4) having a flow cross-sectional area smaller than the flow cross-sectional area of the longitudinal channel (2),
The lower end (22) of the longitudinal channel (2) is arranged above each nozzle opening (3) with respect to the axial direction (A) and with respect to the normal operating position. Nozzle head.   A plurality of nozzle channels (4), each of the plurality of nozzle channels (4) extending from the longitudinal channel (2) to the nozzle opening (3) to burn fuel in the large diesel engine 2. A nozzle head according to claim 1, wherein the nozzle head is adapted to be introduced into the chamber. A longitudinal bore (5) extending in the axial direction;
The longitudinal bore (5) comprises the longitudinal channel (2);
3. A nozzle head according to claim 1 or 2, wherein an insert (6) is provided in the longitudinal bore (5) in which all of the nozzle channels (4) are arranged.   4. A nozzle head according to claim 3, wherein the insert (6) is made from a material different from that used for the rest of the nozzle head (1).   Each nozzle channel (4) is designed such that fuel can be discharged from each nozzle opening (3) at an injection angle (α) inclined with respect to the axial direction (A), and each injection angle (α) is 90 The nozzle head according to any one of claims 1 to 4, wherein the nozzle head is smaller than °, preferably smaller than 80 °.   6. A nozzle head according to claim 5, comprising at least two nozzle channels (4) having different spray angles ([alpha]).   A nozzle according to any one of the preceding claims, wherein each nozzle channel (4) is designed to communicate with the longitudinal channel (2) in the axial direction (A). head.   The at least one nozzle channel (4) according to any one of claims 1 to 7, wherein the at least one nozzle channel (4) is designed to expand or taper in a region adjacent to the nozzle opening (3). The described nozzle head.   9. A nozzle head according to any one of the preceding claims, wherein each nozzle channel (4) is designed with no edges or corners.   The nozzle head according to any one of the preceding claims, wherein the at least one nozzle channel (4) is designed in an arch or curved shape. At least two nozzle channels (4) having a curved region are provided;
11. The nozzle head according to claim ₁ , wherein the curvatures (r ₁ , r ₂ ) of the curved regions of the two nozzle channels (4) are different curvatures. 11. In the manufacturing method of the nozzle head according to any one of claims 1 to 11,
A manufacturing method characterized in that the nozzle head (1) is manufactured using an additional processing method.   The manufacturing method according to claim 12, wherein the entire nozzle head (1) is manufactured using an additional processing method. The insert (6) in which all the nozzle channels (4) are arranged is manufactured using an additional processing method,
13. The insert (6) is inserted into a longitudinal bore (5) of the nozzle head (1), extending in the axial direction (A) and comprising the longitudinal channel (2). Manufacturing method.   A nozzle head according to any one of claims 1 to 11, or a nozzle head (1) manufactured by the manufacturing method according to any one of claims 12 to 14. A large diesel engine having a fuel injection nozzle, particularly a two-stroke large diesel engine scavenged in the longitudinal direction.