EP1565650B1 - Device for injecting fuel - Google Patents

Description

The present invention relates to an injection device for injecting fuel, in particular for injecting fuel into a combustion chamber of an internal combustion engine.

Injection devices for injecting fuel into a combustion chamber of an internal combustion engine are known from the prior art in a wide variety of configurations. In particular, in connection with accumulator injection systems, such as common rail diesel fuel injection systems, such injectors are used for high pressure fuel injection. Such injection devices comprise a nozzle needle guided in a nozzle body, wherein a sealing seat is formed on a tip of the nozzle needle for a seal between the nozzle needle and the nozzle body. Below the sealing seat usually a plurality of injection holes are formed, which branch off from a blind hole in the nozzle body. Through these injection holes, the fuel is injected into the combustion chamber.

Usually, the nozzle body is formed at the end in the form of a cone or truncated cone and the injection holes extend from the outside of the cone inwardly to the blind hole. Due to the arrangement of the injection holes in the conical area results in a non-planar exit surface on the outside of the cone, as shown in Fig. 4. As a result of this, when the fuel jet is viewed in a plane perpendicular to the central axis XX of the spray hole, fuel particles partly already emerge from the injection hole, while at other regions of the spray hole they are still conducted at the spray hole wall. This results in a different deflection of the beam over the exit area and a different fanning of the beam at the exit area.

Furthermore, the different guide length of the fuel particles at the exit region leads to non-symmetrical injection geometries and furthermore also to a geometry of the exit jet which is difficult or impossible to reproduce.

FIG. 5 furthermore shows a known nozzle, which is inclined to a combustion chamber and in which, due to the inclination, different guide lengths of individual injection holes are present. The guide length at the left injection hole 4 is larger by A than at the right injection hole 4 ', where the guide B is. This also causes scattering of the spray pattern from spray hole to spray hole.

Other injectors are known in GB 1088666A and US 4621772A.

It is therefore an object of the present invention to provide an injection device for injecting fuel, which enables an improved injection of fuel.

This object is achieved by an injection device having the features of claim 1. The dependent claims show advantageous developments of the invention.

According to the injection device according to the invention for the injection of fuel, this has an outlet region, which lies in a plane perpendicular to a spray hole axis. In other words, all edge points are located at the exit region of the injection hole in a plane perpendicular to the injection hole axis, so that a planar exit surface is present. This ensures that the fuel is not guided in the exit region of the injection hole for different lengths, so that an optimal discharge of fuel from the injection hole is achieved. In this case, there are no distractions caused by different injection hole lengths or different fanning of the jet. Thus, by the measure according to the invention an exact beam geometry can be obtained. Furthermore, the arrangement according to the invention allows the outlet region in a direction to the injection hole axis vertical plane an exact and faster alignment of the beam. This also allows a more easily reproducible beam geometry, so that the combustion process in the engine can run smoothly. The inventive design of the exit region further improves the atomization within the jet and significantly reduces the pressure dependence of the jet geometry. Another advantage lies in the fact that tests on engine test benches or similar. can be significantly simplified. The exit geometry according to the invention thus provides an optimal exit cone, which leads to an improved combustion process and to improved exhaust emission.

According to the invention, the exit region of the injection hole is arranged on a flat-ground outer region of the housing component. In this way, the exit area according to the invention can also be provided particularly easily. In this case, it is possible to form the planar region on the outside of the housing component either before the injection hole is produced or after the injection hole has been produced.

Furthermore, the outer design of the housing component is designed as a polyhedron. there For example, a polyhedron with a substantially conical basic shape can be produced.

According to a preferred embodiment of the present invention, the outlet region of the injection hole is in a recessed area, in particular by means of depressions. In other words, e.g. a reduction in the outlet region of the spray hole carried out such that after lowering all edge points of the outlet side injection hole end lie in a plane perpendicular to the injection hole axis. Such a reduction can, for example, before or after the production of the injection hole with an appropriately designed drilling tool or by means of spark erosion or the like. be generated.

Further preferably, the housing component, in which the injection hole is arranged, a substantially conical or spherical component.

Further preferably, the injection device according to the invention is mounted inclined to a combustion chamber axis. With such an oblique installation relative to the combustion chamber, the greatest problems have arisen in the state of the art so far, since this results in different length differences and thus different jet geometry of the individual injection holes from injection hole to injection hole. According to the invention, however, this problem can now be solved easily and the same jet geometry can be ensured at each spray hole.

The injection device according to the invention is used in particular in storage injection systems, such as common rail systems, for the injection of fuel under high pressure. In this case, the present invention achieves particularly good injection results with corresponding advantages in terms of combustion and the exhaust gas behavior, because due to the high pressure, a large amount of fuel within a small period of time with a predetermined, easily reproducible beam geometry is injected.

Figur 1

eine schematische Teilschnittansicht einer Einspritzvorrichtung gemäß einem ersten Ausführungsbeispiel der vorliegenden Erfindung,

Figur 2

eine Vergrößerung des mit X in Figur 1 gekennzeichneten Austrittsbereich des Spritzlochs,

Figur 3

eine schematische Schnittansicht eines Austrittsbereichs gemäß einem zweiten Ausführungsbeispiel der vorliegenden Erfindung,

Figur 4

ein Austrittsbereich gemäß dem Stand der Technik, und

Figur 5

eine schematische Schnittansicht einer zum Brennraum geneigten Düse gemäß dem Stand der Technik.

Hereinafter, the present invention will be described by way of preferred embodiments in conjunction with the drawings. In the drawing is:

FIG. 1

FIG. 2 is a schematic partial sectional view of an injection apparatus according to a first embodiment of the present invention; FIG.

FIG. 2

an enlargement of the exit area of the spray hole marked X in FIG.

FIG. 3

a schematic sectional view of an exit region according to a second embodiment of the present invention,

FIG. 4

an exit area according to the prior art, and

FIG. 5

a schematic sectional view of a nozzle inclined to the combustion chamber according to the prior art.

Hereinafter, an injection device 1 for a storage injection system according to a first embodiment of the present invention will be described with reference to Figs.

As shown in Figure 1, the injection device 1 comprises a housing 2 in the form of a nozzle body, in which a blind hole 3 is formed with a seat 10 cone. A sealing seat 8 on the seat 10 is closed or released in a known manner by a nozzle needle, not shown. When released sealing seat flows in a known manner, a pressurized fuel through the blind hole 3 and the injection holes 4 in a combustion chamber of an internal combustion engine.

In Figure 2, the outlet region 5 of the injection hole 4 of the first embodiment is shown in detail. As shown in FIG. 2, a depression 6 is formed at the exit region 5 of the injection hole 4 such that the exit region 5 of the injection hole lies in a plane E. In other words, all edge points 9 of the outlet-side injection hole end lie in a plane E, which is perpendicular to a spray hole axis YY. This design of the outlet side spray hole end an exact and fast alignment of the spray jet is achieved at vorberechenbarer and reproducible beam geometry. In particular, a special uniform beam symmetry of the fuel injected into the combustion chamber can be obtained. Furthermore, the beam is more independent of pressure fluctuations. As a result of the improved atomization in comparison with the conventional injection-hole geometries, an improved combustion process can also be obtained.

Hereinafter, an injection apparatus according to a second embodiment of the present invention will be described with reference to FIG. The same parts are designated by the same reference numerals.

The injection device 1 according to the second embodiment substantially corresponds to that of the first embodiment, wherein instead of the countersinking in the second embodiment, a flat ground area 7 is formed. The plane-ground region 7 forms the plane E, which is arranged perpendicular to the injection-hole axis Y-Y, so that the exit region 5 of the injection hole 4 lies in this plane E. The plane ground area 7 can be generated before or after production of the injection hole 4.

The injection device 1 according to the invention is used in particular in accumulator injection systems, such as common rail systems for injecting diesel fuel under high pressure into a combustion chamber. Here, the inventive design of the outlet-side end of the injection hole shows significant advantages over the conventional, previously used spray hole geometries, especially at high pressures and pressure fluctuations.

Claims (5)

1. Injection device for injecting fuel, in particular into a combustion chamber of an internal combustion engine, comprising a housing component (2) having at least one injection hole (4) which has an inlet area and an outlet area (5), the outlet area (5) lying in a plane (E) perpendicular to an injection hole axis (Y-Y), characterised in that the plane (E) of the outlet area (5) lies in a surface-ground area (7) of the housing component (2) and wherein the external shape of the housing component (2) is a polyhedron.
2. Injection device according to claim 1, characterised in that the outlet area (5) lies in a recessed area (6), in particular an area recessed by means of countersinking.
3. Injection device according to one of the preceding claims, characterised in that the at least one injection hole (4) is disposed in a section of the housing component (2) having an essentially cone- or sphere-like shape.
4. Injection device according to one of the preceding claims, characterised in that the injection device is disposed perpendicular to or inclined at an angle relative to a combustion chamber axis.
5. Injection device according to one of the preceding claims, characterised in that the injection device is used in an accumulator injection system.

Images