INJECTOR FOR INTRODUCING A FLUID WITH IMPROVED FLOW ROBUSTNESS

Abstract

An injector for introducing a fluid. The injector has a valve seat in which a multiplicity of injection holes are formed, and a closing element that releases and closes a fluid path to the injection holes, a size of an inlet area of at least two injection holes being different, and a spacing of the injection holes in the circumferential direction to the adjacent injection hole in each case being selected as a function of the size of the inlet areas of the injection holes.

Claims

1-9. (canceled)

10. An injector for introducing a fluid, comprising: a valve seat in which a multiplicity of injection holes are formed; and a closing element that releases and closes a fluid path to the injection holes, a size of an inlet area of at least two of the injection holes being different from one another; wherein a spacing in a circumferential direction of the injection holes to each adjacent injection hole is selected as a function of a size of inlet areas of the injection holes.

11. The injector as recited in claim 10, wherein a circular segment going out from a center axis of the injector is assigned to each injection hole of the injector holes, each injection hole center axis is situated in a range of ±5° around a center line of the circular segment, sizes of the circular segments being selected corresponding to the sizes of the inlet areas of the injection holes.

12. The injector as recited in claim 11, wherein each of the injection holes is situated on the center line of a circular segment of the circular segments.

13. The injector as recited in claim 10, wherein the injection area of each of a largest injection hole of the injection holes and a smallest injection hole of the injection holes differs by a maximum of 45% from an average value of all inlet areas of the injection holes.

14. The injector as recited in claim 10, wherein each injection hole has an injection hole center axis that has a radial distance to a center axis of the injector, each of the radial distances of the injection hole center axes differing by a maximum of 30% from an average value of all radial distances of the injection hole center axes to the center axis of the injector.

15. The injector as recited in claim 14, wherein all injection hole center axes are situated at the same radius around the center axis.

16. The injector as recited in claim 10, wherein the injector has from five to seven injection holes.

17. The injector as recited in claim 10, wherein the injector is an inwardly opening injector.

18. The injector as recited in claim 10, wherein the injector is a fuel injector or a urea injector or a water injector.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the following, a preferred exemplary embodiment of the present invention is described in detail with reference to the figures.

[0015] FIG. 1 shows a schematic sectional view of an injector for introducing a fluid according to a preferred exemplary embodiment of the present invention.

[0016] FIG. 2 shows a schematic top view of an inner region of a valve seat of the injector, the inlet areas of the injection holes being shown schematically.

[0017] FIG. 3 shows a schematic representation of the configuration of the injection holes, also showing circular segments in the shape of pie slices.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0018] In the following, an injector 10 according to a preferred exemplary embodiment of the present invention is described in detail with reference to FIGS. 1 through 3.

[0019] Injector 10 is a fuel injector for the direct injection of fuel into a combustion chamber of an internal combustion engine. Injector 10 includes a closing element 20 in the form of a valve needle on whose free end there is situated a ball 21. The closing element is pressed into a closed position, shown in FIG. 1, by a reset element 9.

[0020] In this exemplary embodiment, injector 10 is an inwardly opening injector, closing element 20 being moved against the reset force of reset element 9 in order to open injector 10.

[0021] Injector 10 includes a multiplicity of injection holes 30, situated in a valve seat 8 of the injector.

[0022] In this exemplary embodiment, as shown schematically in FIGS. 2 and 3, five injection holes 30 are provided. Injection holes 30 are numbered consecutively with the numerals 1 through 5 in FIGS. 2 and 3 in order to facilitate the assignment of the injection holes in the following description.

[0023] Closing element 20 is actuated by actuator 40, which in this exemplary embodiment is a magnetic actuator. However, it is to be noted that a piezo actuator may also be provided for the actuation of closing element 20.

[0024] Closing element 20 thus releases or closes a fluid path to a sealing seat 7 for the fuel to be injected.

[0025] As can be seen in FIGS. 2 and 3, injection holes 30 are positioned in a particular geometric configuration, and are also geometrically formed differently. In particular, the inlet areas, indicated in FIGS. 2 and 3 by the size of the circles of injection holes 30, are different. Here, the injection holes having numbers 2 and 5 are made with the largest inlet areas, and the injection holes having numbers 3 and 4 are made with the smallest inlet areas. The injection hole having number 1 is between the injection holes having numbers 2 and 5, as well as 3 and 4, with regard to the size of the inlet areas.

[0026] In addition, a spacing of the respectively adjacent injection holes 30 in the circumferential direction is selected as a function of the size of the inlet areas of injection holes 30. In this way, it is ensured that the largest quantities of fuel can flow to the injection holes having numbers 2 and 5 when the injector is open, without there being local oversupplying or competition with regard to the mass distribution of the fuel to the respective injection holes.

[0027] Here, each injection hole has assigned to it a pie piece-shaped circular segment (see FIG. 3), an injection hole center axis S lying in each case on a center line M of a circular segment.

[0028] In addition, injection hole center axes S are all situated at a common radius R about a center axis X-X of injector 10.

[0029] As can be seen in FIG. 3, a separate pie piece-shaped circular segment is assigned to each injection hole. Here, the size of an area of the circular segment corresponds to the ratio of the sizes of the inlet areas of the injection holes to one another. That is, the two largest injection holes, having numbers 2 and 5, also have the largest circular segments.

[0030] In addition, the largest and the smallest injection hole 30 have an inlet area that is a maximum of 45% of an average value of all inlet areas. The average value of the inlet areas is obtained by addition of the individual inlet areas and division by the number of injection holes.

[0031] The sizes of the circular segments are then selected corresponding to the sizes of the inlet areas of injection holes 30. It is to be noted that midpoints S of the injection holes do not necessarily have to lie on the center lines of the circular segments, but can have a deviation of ±5°.

[0032] In FIG. 3, an arc length of the circular segment at the first injection hole, having number 1, is defined by the circular angle α1. A circular segment at the second injection hole, having number 2, is defined by the circular arc α2.

[0033] Correspondingly, the center lines of the circular segments are also defined by the arcs α1/2 and α2/2.

[0034] Thus, injector 10 according to the present invention can provide an increase in a flow robustness compared to the related art. In particular, it is possible to achieve reduced scattering of injected quantities, both at different injectors and also at one injector in successive injections. In addition, a particularly homogenous flow distribution of the fuel mass flow, without mutual interference of adjacent injection holes, is achieved. In FIG. 2, the arrows again schematically show the apportioning of the overall fuel mass flow to the individual injection holes 30 when the injector is open. The size of the arrows corresponds to the size of the portion in the overall mass flow. Because the circular segments assigned to the individual injection holes correspond to the mass flow portion of the respective injection holes 30, a flow robustness when the injector is open can be significantly improved.