Component, especially a high-pressure component for fuel injection systems, and method for producing a component of this type

Abstract

In a component, in particular a high-pressure part for a fuel injection system, having intersecting bores, at least one bore of the two intersecting bores is designed with a flat region, and the component has inherent compressive stresses in the area of the flat region of the bore. This yields an increase in strength of the component in the area of the intersection point of the two bores.

Description

FIELD OF THE INVENTION

[0001] The present invention relates to a component and a method for producing such a component.

BACKGROUND INFORMATION

[0002] The related art includes British Patent Nos. 2,322,919, 2,322,920, 2,322,321 and 2,322,922 as well as German Published Patent Application No. 198 08 894.

[0003] In conjunction with the present invention, a number of possible components which have intersecting bores in the interior, in particular CR injectors (CR=common rail) are of interest. Not only are these components under a very high internal pressure in the fuel injection system, but also the internal pressure is subject to great periodic fluctuations (pulsating internal pressure), so they must meet high strength requirements accordingly. The strength of the bore intersections is especially important.

SUMMARY OF THE INVENTION

[0004] An object of the present invention is to further increase the strength of bore intersections in components of the aforementioned type with respect to the internal compressive stresses that occur.

[0005] On the basis of the non-cutting shaping of the component in particular by pressure acting from the outside, a controlled flattening of the bore at the point of intersection of the respective bores can be achieved without any great technical complexity or cost expenditure.

[0006] The desired increase in the strength of the component is derived through inherent compressive stresses produced in a controlled manner directly at the most highly stressed point in the component, the bore intersections. Better utilization of the material is also achieved due to the increased strength of the component at these locations, which are exposed to extreme loads.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 shows an embodiment of a CR injector shown in cross section where the component is still undeformed.

[0008] FIG. 2 shows the object from FIG. 1 shown in a cross-sectional diagram according to FIG. 1 (section II-II in FIG. 3) after non-cutting shaping of the component.

[0009] FIG. 3 shows the object from FIG. 2 as seen in the direction of arrow “A”.

[0010] FIG. 4 shows a slightly modified variant of a CR injector in comparison with FIGS. 1 through 3, shown in a cross-sectional diagram according to FIG. 1 or 2, where the component is still undeformed.

[0011] FIG. 5 shows the object from FIG. 4 shown in a corresponding cross-sectional diagram, but after non-cutting shaping of the component.

[0012] FIG. 6 shows a CR injector according to FIG. 1 in a corresponding cross-sectional diagram (section VI-VI in FIG. 7), with the female die inserted.

[0013] FIG. 7 shows a section along line VII-VII in FIG. 6.

DETAILED DESCRIPTION

[0014] FIGS. 1 through 3 show an essentially cylindrical component 10 which is part of the CR injector. In its prefabricated state as shown in FIG. 1, component 10 has a continuous bore 11 with a circular cross section. A second bore 12 with a much smaller cross section opens at 13 into first bore 11 at a right angle to it. FIGS. 1 and 2 show clearly that central axes 14, 15 of two bores 11, 12 intersecting at 13 do not meet at the center of component 10. Second bore 12 thus opens eccentrically into first bore 11.

[0015] FIG. 2 shows that first bore 11 (still circular in the partially shaped state according to FIG. 1) has a flat region 16 in the area of intersection 13 of two bores 11, 12. Flat region 16 is the intentional result of non-cutting shaping of component 10 produced by pressure acting from the outside (in the direction of arrow 17) via a rectangular ram 18 (see FIG. 1).

[0016] As shown in FIGS. 2 and 3, this results in a groove-shaped deformation 19 on the outer circumference of component 10, although it is limited only to the area of second bore 12 and its intersection 13 with first bore 11, like flat region 16 produced by the pressure acting on it. Inherent compressive stresses thus build up in the area around intersection point 13, thereby greatly increasing the strength of component 10 in this area. The material area surrounding intersection point 13 of two bores 11, 12 meets extremely high strength requirements due to the pulsating compressive stress caused by the liquid medium (e.g., fuel) flowing through the bores.

[0017] The component labeled 10a in FIGS. 4 and 5 is similar in design to component 10 in FIGS. 1 through 3. In particular, like the latter, it also has a continuous bore 11 with a large diameter and a second bore 12 with a much smaller diameter opening into the former eccentrically at a right angle. One difference in comparison with the embodiment according to FIGS. 1 through 3 is that in its processed state (FIG. 4), component 10a has a noncontinuous starting bore 20 which is directed at intersection point 13 of two bores 11, 12. To produce a local flat region 21 of bore 11 directly at opening point 13 of bore 12 (see FIG. 5), a ram 22 is inserted into starting bore 20 (see FIG. 4) and is acted upon by a force in the direction of arrow 23. Ram 22 may have a circular or oval cross section. With regard to the resulting increase in strength in the area of intersection point 13, the statements made in this regard concerning the embodiment according to FIGS. 1-3 are also applicable here accordingly.

[0018] One particular feature of the variant according to FIGS. 6 and 7 is that a female die labeled 24 on the whole is inserted into continuous bore 11 of component 10, which otherwise corresponds to the embodiment according to FIG. 1.

[0019] As shown in particular in FIG. 6, female die 24 is composed of two “halves” 25, 26 which are subdivided essentially horizontally and, when assembled, yield a circular cross section of female die 24 corresponding to the cross section of bore 11. Upper half 26 of female die 24 has a trough-shaped recess 27 at intersection point 13 of two bores 11, 12.

[0020] If, according to the embodiment illustrated in FIGS. 1 through 3, component 10 is acted upon by pressure in the direction of arrow 17 due to a ram 18 at the level of bore 12 (see FIG. 1), the material of component 10 is deformed according to the aforementioned shape of die recess 27 and into it so that a corresponding local flat region of bore 11 is formed (only) at intersection point 13 of two bores 11, 12. With regard to the resulting increase in strength in the area of intersection point 13, the statements made in this regard concerning the embodiments according to FIGS. 1 through 3 and FIGS. 4 through 5 are also applicable here accordingly. Female die 24 and trough-shaped recess 27 assist the shaping of the flat region and thus facilitate the development of the desired inherent compressive stresses in the material area of intersection point 13.

Claims

1. A component, in particular a high-pressure part (10, 10a) for a fuel injection system, having intersecting bores (11, 12), wherein at least one bore (11) of the two intersecting bores (11, 12) is designed with a flat region, and the component (10, 10a) has inherent compressive stresses in the area of the flat region (16, 21, 27) of the bore.

2. The component according to claim 1 having a continuous bore (11) and a second bore (12) which opens into it at an angle of 90° or essentially 90°, wherein the first continuous bore (11) is designed with a flat region in the direction of opening of the second bore (12) (FIGS. 2 and 5).

3. The component according to claim 1 or 2, wherein the flat region (16, 21, 27) on at least one bore (11) of the two intersecting bores (11, 12) is provided only in the area of the intersection point (13).

4. The component according to claim 1, 2 or 3, the intersecting bores (11, 12) having different diameters, wherein at least the bore (11) with the larger diameter is designed with a flat region.

5. The component according to claim 4, the diameter of the one bore (11) amounting to a multiple of the diameter of the other bore (12), wherein only the bore (11) with the larger diameter has a flat region, while the bore (12) with the smaller diameter has a circular cross section.

6. The component according to claim 4 or 5, wherein the bore (12) with the smaller diameter opens eccentrically into the flat region (16, 21, 27) of the bore (11) with the larger diameter (FIGS. 2, 5 and 6).

7. The component according to one or more of the preceding claims, wherein the dimensions of the flat region (16, 21, 27) are larger than the diameter of the smaller bore (12) but are smaller than the diameter of the larger bore (11).

8. A method of producing a component according to one or more of the preceding claims, wherein at least one bore (11) of the intersecting bores (11, 12) which initially have a circular cross section is flattened by non-cutting shaping of the component (10, 10a).

9. The method according to claim 8, wherein the shaping is performed on the partially shaped component (10, 10a).

10. The method according to claim 8 or 9, wherein shaping to produce the flat region (16, 21, 27) is performed by a pressure acting on the component (10, 10a) from the outside.

11. The method according to claim 8, 9 or 10, wherein shaping to produce the flat region (16, 21, 27) is performed by a pressure acting on the component (10, 10a) via a ram (18, 22) approximately at the location (19, 20) of the outer lateral surface of the component (10, 10a) where the two bores (11, 12) intersect in the interior.

12. The method according to claim 11, wherein the acting pressure is applied by a ram (18, 22) whose dimensions correspond approximately to the desired contours of the flat region (16 or 21) to be produced.

13. The method according to claim 11 or 12, wherein the acting pressure is applied by a ram (18) having a rectangular cross section (FIGS. 1 through 3).

14. The method according to claim 11 or 12, wherein the acting pressure is applied by a ram (22) having a circular cross section or an essentially circular cross section which is directed at an acute angle to the opening bore (12) at the desired location of the flat region(21) to be produced (FIGS. 4 and 5).

15. The method according to one or more of claims 8 through 14, wherein a female die (24) is inserted into the bore (11) which is to be flattened and has a recess (27) corresponding to the desired contours of the flat region at the location (13) which corresponds to the location of the (subsequent) flat region and then non-cutting shaping of the component (10) is performed (FIGS. 6 and 7).