METHOD FOR PRODUCING A NOZZLE BODY FOR A FLUID INJECTION VALVE, AND FLUID INJECTION VALVE

Abstract

A method for producing a nozzle body for a fluid injection valve includes supplying a nozzle body blank having a nozzle body tip and introducing a nozzle body recess into the nozzle body blank, starting from a first axial end, and thereby forming a wall. The method furthermore includes supplying geometry data of at least one injection hole to be provided, with an inner opening and an outer opening, and determining a height of a blind hole step of a blind hole to be formed, in a manner dependent on a predefined fluid penetration. The method furthermore includes adapting a part of the shape of an inner surface of the wall and thereby forming the blind hole with the blind hole step of the determined height and introducing the at least one injection hole with the supplied geometry data, so that the at least one injection hole penetrates the wall.

Claims

1. A method for producing a nozzle body for a fluid injection valve, comprising: supplying a nozzle body blank, which has a longitudinal axis as well as a first axial end and a second axial end with a nozzle body tip in relation to the longitudinal axis, introducing a nozzle body recess into the nozzle body blank, starting from the first axial end, and thereby forming a wall between the nozzle body recess and an outer surface of the nozzle body blank, supplying geometry data of at least one injection hole to be provided, for penetrating the wall as far as the outer surface, starting from the nozzle body recess, with an inner opening, which faces the nozzle body recess, and an outer opening which faces the outer surface, determining a height of a blind hole step of a blind hole to be formed, in a manner which is dependent on a predefined fluid penetration, starting from the outer opening of the respective injection hole, into the environment of the nozzle body, adapting a part of the shape of an inner surface of the wall and thereby forming the blind hole with the blind hole step of the determined height in relation to the longitudinal axis in a region of the second axial end of the nozzle body blank, and introducing the at least one injection hole into the wall with the supplied geometry data in a region of the blind hole between a blind hole step end facing the second axial end and the nozzle body tip in such a way that the at least one injection hole penetrates the wall.

2. The method as claimed in claim 1, wherein the injection hole is shaped in such a way that the injection hole penetrates the wall without a step from the inner surface to the outer surface.

3. The method as claimed in claim 1, wherein adapting a part of the shape of an inner surface of the wall and consequent formation of the blind hole with the blind hole step of the determined height is accomplished by reducing the wall thickness of a part of the wall between the nozzle body recess and the outer surface.

4. The method as claimed in claim 2, wherein a length and a diameter are specified as geometry data of the at least one injection hole in order to achieve the predefined fluid penetration, and the height of the blind hole step is chosen in such a way that the blind hole step reduces the wall thickness between the inner surface and the outer surface to such an extent that, when the injection hole with the determined length and the outer opening in the outer surface is introduced, the inner opening is positioned in the inner surface.

5. The method as claimed in claim 1, wherein the supplied geometry data comprise a first diameter and a second diameter of the at least one injection hole, such that the injection hole to be introduced is conical, and the first diameter and the second diameter are determined in a manner dependent on the predefined fluid penetration, wherein the first diameter is assigned to the inner opening and the second diameter is assigned to the outer opening.

6. The method as claimed claim 5, wherein the first diameter and the second diameter of the at least one injection hole are additionally determined in a manner dependent on the determined height.

7. The method as claimed in claim 1, wherein adapting a part of the shape of the inner surface of the wall comprises forming a seat region for a nozzle needle adjoining the blind hole step in a direction of the first axial end.

8. The method as claimed in claim 1, wherein adapting a part of the shape of the inner surface of the wall comprises forming a guiding region for guiding a nozzle needle in the region of the first axial end in a direction of the second axial end.

9. A fluid injection valve for a motor vehicle, comprising: a nozzle body which is produced by a method recited in claim 1, and a nozzle needle which is arranged at least partially in the nozzle body recess in such a way as to be axially movable in relation to the longitudinal axis and which is designed to prevent a fluid flow in interaction with a seat region in a closed position and otherwise to allow said flow.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Illustrative embodiments of the invention are explained in greater detail below with reference to the schematic drawings. In the drawings:

[0047] FIG. 1 shows a flow diagram of a method for producing a nozzle body, and

[0048] FIG. 2 shows an illustrative embodiment of a nozzle body in a schematic longitudinal section.

DETAILED DESCRIPTION

[0049] FIG. 1 shows an example of a flow diagram of a method for producing a nozzle body 1 for a fluid injection valve, which is started in a step S1 and in which a nozzle body blank is supplied, which has a longitudinal axis A as well as a first axial end 3 and a second axial end 5 with a nozzle body tip 20 in relation to the longitudinal axis A.

[0050] In a subsequent further step S3, a nozzle body recess 7 is introduced into the nozzle body blank, starting from the first axial end 3, and a wall 9 is thereby formed between the nozzle body recess 7 and an outer surface 11 of the nozzle body blank. The nozzle body recess 7 is formed in the nozzle body blank by boring and/or turning, for example.

[0051] In a further step S5, a geometry of at least one injection hole 17 to be provided is supplied, which is intended to penetrate the wall 9 as far as the outside, starting from the nozzle body recess 7, with an inner opening 18, which faces the nozzle body recess 7, and an outer opening 19, which faces the outer surface 11.

[0052] The geometry supplied includes a diameter and a length L and a diameter for a cylindrical injection hole 17 to be formed, for example. As an alternative, the supplied geometry includes a first diameter D1, a second diameter D2 and a length L of a conical injection hole 17 to be formed. If a plurality of injection holes 17 are provided for the nozzle body 1, optionally some of the injection holes 17 are cylindrical and some conical. Moreover, other geometries of the injection holes 17 are also possible. The supplied geometry data for each injection hole 17 preferably additionally comprise at least one element from the following group: distance from the longitudinal axis A, axial position in relation to the longitudinal axis A, angular position in relation to the longitudinal axis A, slope in relation to the longitudinal axis A.

[0053] In an optional step S6, the geometry to be supplied is determined in a manner dependent on a predefined fluid penetration, starting from the outer opening 19 of the respective injection hole 17, to the outside of the nozzle body 1. For example, values for diameters D1 and D2 and the length L of a conical injection hole 17 are determined in this way, making a contribution to the achievement of a desired fluid penetration.

[0054] This takes account of the fact that the fluid penetration from an injection hole 17 into a combustion chamber of an internal combustion engine is dependent inter alia on the geometry of the respective injection hole 17. In this way, fluid penetration may be adapted individually for each injection hole 17 within certain limits.

[0055] In a further step S7, a height H of a blind hole step 15 of a blind hole 13 to be formed is determined in a manner which is dependent on the predefined fluid penetration, starting from the outer opening 19 of the respective injection hole 17, to the outside of the nozzle body 1.

[0056] In this way, it is possible to control fluid penetration by determining and subsequently forming the blind hole step 15 with the height H and, inter alia, to make a contribution to combating soot formation on the nozzle body tip 20. A nozzle body 1 which has a blind hole contour determined in a manner dependent on a desired fluid penetration thus allows reliable operation of a fluid injection valve comprising the nozzle body 1 that is to be produced and contributes to a longer service life.

[0057] The formation of the blind hole step 15 of the determined height H affects the fluid penetration associated with all the injection holes 17 to be introduced since the blind hole step 15 is arranged ahead of the inner opening 18 of the respective injection hole 17 that is still to be introduced, in relation to a flow direction of a flowing fluid. In respect of a finished nozzle body 1, the respective injection hole 17 is then arranged after the blind hole step 15 in relation to the flow direction of a fluid. In other words, the at least one injection hole 17 provided is formed between one blind hole step end 16 of the blind hole step 15 and the nozzle body tip 20.

[0058] As an option, the height H of the blind hole step 15 is additionally determined in a manner dependent on the supplied and possibly determined geometry of the at least one injection hole 17 to be formed.

[0059] This takes into account the fact that fluid penetration is dependent on interaction between the length L and diameter of a cylindrical injection hole 17 and the height H of the blind hole step 15, for example. These parameters may be matched to one another in mutual dependence in such a way that a desired fluid penetration is achieved. In this way, it is possible, for example, to meet fluid penetration requirements that may be achieved only with difficulty by the formation of the blind hole step 15 alone. It is then useful, for example, to additionally determine a value for the height H of the blind hole step 15 in a manner dependent on the geometry of the injection hole 17 in order in this way to achieve the desired fluid penetration and allow a simple production process.

[0060] In a further step S9, a part of the shape of an inner surface of the wall 9 is adapted and the blind hole 13 with the blind hole step 15 of the determined height H in relation to the longitudinal axis A is thereby formed in a region of the second axial end 5 of the nozzle body blank.

[0061] In respect of advantageous symmetrical formation of the nozzle body 1 and of a device for a fluid injection valve, the blind hole step 15 is formed substantially parallel to the longitudinal axis A of the nozzle body 1. In another embodiment, however, it is also possible for the blind hole step 15 to have a slope relative to the longitudinal axis A and thereby to influence fluid penetration. In such a case, the height H of the blind hole step 15 then relates, for example, to a projection of the geometrical length thereof parallel to the longitudinal axis A.

[0062] Adaptation of a part of the shape of the inner surface of the wall 9 also includes forming a seat region 21 for a nozzle needle adjoining the blind hole step 15 in the direction of the first axial end 3 and thus remote from the nozzle body tip 20, for example. In a closed position, the seat region 21 prevents fluid flow in interaction with a sealing seat of the nozzle needle, and otherwise allows flow in an open position.

[0063] As an option, adaptation of a part of the shape of the inner surface of the wall 9 also includes forming a guiding region 23 for guiding the nozzle needle in the region of the first axial end 3 in the direction of the second axial end 5.

[0064] In a further step S11, the at least one injection hole 17 is introduced in a region of the blind hole 13 between the blind hole step end 16 facing the second axial end 5 and the nozzle body tip 20 with the supplied geometry data and, if appropriate, in a manner dependent on the predefined fluid penetration and/or the determined height H of the blind hole step 15. For example, the at least one injection hole 17 is introduced into the nozzle body blank by boring and/or turning and, in this way, the nozzle body 1 is formed.

[0065] In a step S13, the method for producing the nozzle body for a fluid injection valve is ended.

[0066] In a development, determination of the height H is carried out in a manner dependent on the predefined geometry datae.g. in a manner dependent on the length L, the slope and the distance from the longitudinal axisand on the shape of the nozzle body blank. In this case, the height H, in particular, is chosen in such a way that the blind hole step 15 reduces the wall thickness of the wall 9 to such an extent that the injection hole 17 introduced into the wall 9 in accordance with the supplied geometry data penetrates the wall downstream of the blind hole step 15 from the inner surface 10 thereof to the outer surface 11 of the nozzle body 1in particular without a step.

[0067] FIG. 2 shows a section through an illustrative embodiment of the nozzle body 1, which has been produced by means of the method described in FIG. 1, for example. The nozzle body 1 has the first axial end 3, the second axial end 5 and the longitudinal axis A and is of substantially rotationally symmetrical design.

[0068] The wall 9 forms the nozzle body recess 7 and includes the guiding region 23, the seat region 21 and a blind hole contour of the blind hole 13 with the blind hole step 15, which blind hole step is formed with the height H determined in a manner dependent on the predefined fluid penetration. The blind hole step 15 is formed coaxially with the longitudinal axis A in the shape of the lateral surface of a cylinder. In other embodiments, the blind hole step 15 may have a slope relative to the longitudinal axis A, with the result that the nozzle body 1 includes a frustoconical blind hole step 15.

[0069] In this illustrative embodiment, the nozzle body 1 has a conical injection hole 17 below the blind hole step 15, to be precise between the blind hole step end 16 and the nozzle body tip 20. The first diameter D1 is associated with the inner opening 18 and is of smaller design than the second diameter D2, which is associated with the outer opening 19 of the injection hole 17.

[0070] Accordingly, the injection hole 17 has a cone angle K, which may affect fluid penetration. The cone angle K is determined by the two diameters D1 and D2 and the length L of the injection hole 17 and is supplied as the geometry of the injection hole 17 in the context of the production of the nozzle body 1 and has optionally been determined in a manner dependent on a desired fluid penetration.

[0071] The nozzle body 1 makes possible a desired fluid penetration in a simple manner by means of the blind hole step 15 formed in a controlled manner and having the determined height H and thereby makes possible reliable operation of an associated fluid injection valve. It contributes to keeping down pollutant emissions in an internal combustion engine.

[0072] A number of implementations have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other implementations are within the scope of the following claims.