Method for producing an injector

Abstract

A method for producing an injector which is designed in particular to inject fuel into an induction pipe or directly into a combustion chamber of an internal combustion engine. The method includes providing an injector base element, providing a rod that is insertible into a through hole of the injector base element, producing a negative matrix of a spray orifice element on an axial end of the rod, inserting the rod into the through hole of the injector base element, positioning the negative matrix situated on the rod relative to the injector base element, producing the spray orifice element having at least one spray orifice by applying a galvanization layer on a downstream end, in the injection direction, of the injector base element and on the negative matrix, and removing the rod and the negative matrix.

Claims

1. A method for producing an injector, which is designed to inject fuel into an induction pipe or directly into a combustion chamber of an internal combustion engine, the method comprising: providing an injector base element; providing a rod that is a solid complete form that is slidable, as a whole, into and out of a through hole of the injector base element; producing a negative matrix of a spray orifice element on an axial end of the rod; sliding the rod into the through hole of the injector base element; positioning the negative matrix situated on the rod relative to the injector base element; producing the spray orifice element having at least one spray orifice by applying a galvanization layer on a downstream end, in an injection direction, of the injector base element and on the negative matrix; and removing the rod and the negative matrix by sliding the rod out of the through hole.

2. The method as recited in claim 1, wherein the negative matrix of the spray orifice element is produced by microscaled 3D printing.

3. The method as recited in claim 1, wherein the negative matrix is formed from a photopolymer.

4. The method as recited in claim 1, wherein the negative matrix is positioned relative to the injector base element by a fit of the rod.

5. The method as recited in claim 1, wherein prior to applying the galvanization layer, an electrically conductive layer is applied at least to a subsection of the negative matrix in order to apply the galvanization layer on the negative matrix and on the injector base element.

6. The method as recited in claim 5, wherein the electrically conductive layer is a silver conductive paint or a graphite conductive spray.

7. The method as recited in claim 1, wherein the negative matrix is formed at least partially from an electrically conductive material.

8. The method as recited in claim 1, wherein the negative matrix has at least one protruding element by which the spray orifice is formed in the spray orifice element.

9. The method as recited in claim 8, wherein at least one subsection of the protruding element is not provided with an electrically conductive layer and/or is not formed from an electrically conductive material.

10. The method as recited in claim 1, wherein the spray orifice element is made of nickel.

11. The method as recited in claim 1, wherein the negative matrix of the spray orifice element is removed by a mechanical or thermal or chemical treatment.

12. The method as recited in claim 1, further comprising: processing the injector further, the processing further including machining the injector base element and the spray orifice element, following the removal of the negative matrix, in order to clear the spray orifice and/or to shape it further.

13. The method as recited in claim 1, wherein the negative matrix is positioned relative to the injector base element by a shoulder of the rod.

14. The method as recited in claim 1, wherein the inserting of the rod includes shifting a portion of the rod axially within the through hole towards the downstream end of the injector base element, until a shoulder of the rod, which is outside of the through hole abuts against a surface at an upstream end of the injector base element.

15. An injector for injecting fuel into an induction pipe or directly into a combustion chamber of an internal combustion engine, the injector comprising: an injector base element; a rod that has been inserted into a through hole of the injector base element and that is slidable out of the through hole; a spray orifice element; and a negative matrix of a first portion of the spray orifice element on an axial end of the rod; wherein: the spray orifice element includes at least one spray orifice, is partly on a downstream end, in an injection direction, of the injector base element, and is partly on the negative matrix; and the rod and the negative matrix are removable by a sliding of the rod out from the through hole, while leaving an entirety of the spray orifice element intact, with the first portion of the spray orifice element spanning across a downstream end of the through hole.

16. A method for producing an injector, the method comprising: inserting a rod into a through hole of an injector base element, wherein a negative matrix of a spray orifice element is arranged on an axial end of the rod; producing the spray orifice element having at least one spray orifice by: applying a layer having an electrically conductive surface such that (1) a first portion of the layer is arranged on a downstream end, in an injection direction, of the injector base element and (2) a second portion of the layer, which is radially interior to the first portion of the layer, is arranged on the negative matrix; inserting the electrically conductive surface of the applied layer into an electrolyte bath; and controlling a voltage course to apply an electrical voltage to the electrolyte bath, the electrolyte bath thereby forming a metal coating on the electrically conductive surface; and removing the rod and the negative matrix by drawing the rod out of the through hole from an upstream end of the injector base element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Below, the present invention is described with reference to an exemplary embodiment in conjunction with the figures. Functionally identical parts are respectively provided with the same reference symbols in the figures.

(2) FIG. 1 shows a simplified schematic view of the production of an injector by galvanization in accordance with an exemplary embodiment of the present invention.

(3) FIG. 2 shows an enlarged schematic view of a rod having a negative matrix.

(4) FIG. 3 shows an enlarged schematic view of a negative matrix.

(5) FIG. 4 shows a schematic detailed view of an injector base element together with a spray orifice element following galvanization.

(6) FIG. 5 shows a simplified schematic view of an injector, obtainable by the method according to the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(7) FIG. 1 shows a method step of the production of an injector 1, a spray orifice element 5 being produced by galvanization on a downstream end 22, in the injection direction, of an injector base element 2. The method is presented at a point in time at which the spray orifice element 5 is already developed as a galvanization layer, that is, directly prior to the end of the galvanization step.

(8) To produce the spray orifice element 5 from a galvanization layer, an injector assemblage 10 is immersed in a galvanization bath 51 in a vessel 52. Injector assemblage 10 comprises an injector base element 2, a rod 3 and a negative matrix 4 of the spray orifice element 5 that is to be produced. The injector base element 2 is designed as a standard part and may be used as a basis for injectors having different spray orifice elements 5.

(9) Injector base element 2 is respectively shown in the figures as a sectional drawing, the rod 3 and negative matrix 4 being respectively shown in a non-sectional view.

(10) Injector base element 2 has a through hole 21, in which rod 3 is inserted. Negative matrix 4 is situated on an axial end 31 of rod 3, which determines the shape of spray orifice element 5 and spray orifices 6.

(11) For an optimal definition of the geometries of spray orifice element 5, it is necessary to position negative matrix 4 precisely relative to injector base element 2 prior to galvanization. Negative matrix 4 is axially positioned by way of a shoulder 32 on rod 3. If rod 3 is inserted completely into through hole 21 of injector base element 2, shoulder 32 abuts on injector base element 2. In the radial direction, negative matrix 4 is positioned by a fit of rod 3 and of through hole 21 of injector base element 2.

(12) Spray hole element 5 is produced by galvanization. For this purpose, using a voltage source 53, an electrical voltage is applied to injector assemblage 10 and to galvanization bath 51, which is a nickel electrolyte in the exemplary embodiment shown. As a result, a nickel coating is deposited on those regions of the injector assemblage 10 that are immersed into galvanization bath 51 and that have an electrically conductive surface. In the present case, this is the downstream end 22 of injector base element 2 and a subsection of negative matrix 4, which has an electrically conductive surface.

(13) FIGS. 2 and 3 show an enlarged view of rod 3 with negative matrix 4 in two different views, a state being shown prior to the insertion into the injector base element, that is, still without the galvanization layer. Negative matrix 4 is situated on an axial end 31 of the rod. Negative matrix 4 is furthermore formed from a photopolymer and produced by 3D printing. A cylindrical area 43 of negative matrix 4 has the same diameter as rod 3. Negative matrix 4 additionally has protruding elements 42, which form spray orifices 6 in spray orifice element 5. In the exemplary embodiment, negative matrix 4 has five protruding elements 42, as shown in FIG. 3, only three protruding elements 42 or three spray orifices 6 being shown in the schematic views of the further figures for reasons of clarity. Additionally, for better clarity, in the figures, respectively only one of protruding elements 42 or spray orifices 6 is marked with a reference symbol.

(14) Producing negative matrix 4 by 3D printing is particularly advantageous for a favorable and flexible production of injector 1. Thus, it is for example possible to achieve very precise dimensions and the greatest variety of shapes of protruding elements 42 and thus of spray orifices 6. Furthermore, it is a simple matter to produce injectors 1 having different spray orifice elements 5 by merely using different negative matrices 4, the method for producing injector 1 remaining unchanged.

(15) A subsection of negative matrix 4 is provided with an electrically conductive layer 41, in the present exemplary embodiment with a silver conductive paint. As shown in FIG. 2, only one end face of negative matrix 4 facing away from rod 3 is provided with electrically conductive layer 41. Spray orifice element 6 is formed on this electrically conductive layer 41 in the galvanization process shown in FIG. 1. Since the surface of protruding elements 42 is not electrically conductive, no galvanization layer is formed here in the galvanization process.

(16) FIG. 4 shows a detail of injector assemblage 10 after galvanization, only a subsection of injector assemblage 10 being shown. The galvanization process forms a thin layer of nickel on the downstream end 22 of injector base element 2 as well as on electrically conductive layer 41 of the negative matrix. This thin plate-shaped nickel layer forms spray orifice element 5. The protruding elements 42 of negative matrix 4 form spray orifices 6 in spray orifice element 5 after their removal.

(17) Following the galvanization process, rod 3 and negative matrix 4 may be removed. Rod 3 and negative matrix 4 may be removed simultaneously or one after the other. The removal is performed with the aid of a mechanical or thermal or chemical treatment.

(18) Subsequently, injector 1 may receive further processing. FIG. 5 shows an injector 1, which is processed further by machining, a bevel being provided on the outer contour of spray orifice element 5. It is furthermore possible to process spray orifices 6 further in order to optimize their geometry further or in order to deburr spray orifices 6.