DE102012106585A1 - Method for producing a high-pressure fuel line - Google Patents

Abstract

The present invention relates to a method for producing a high-pressure fuel line (1), a fuel pipe (2) being widened at least in sections in the longitudinal direction and then a holder (6) being pressed onto the widened receiving section (10). In order to further increase the strength of the coupling, it is possible according to the invention to additionally couple it with a material fit using a soldering process.

Description

The present invention relates to a method for producing a high pressure fuel line according to the features in claim 1.

In the prior art, it is known in internal combustion engines to inject the fuel directly into the combustion chamber. For this purpose, with pressures of up to more than 200 MPa, the fuel is injected via fuel injectors directly into the combustion chamber of the engine. Such fuel rail systems are also called common rail systems. In particular, these are used in diesel engines, but increasingly more so in engines that are operated with gasoline fuel.

Within the lines thus prevails a pressure of up to more than 200 MPa, which due to the injection through the injectors, there is pressure pulsations within the line, which are transmitted to the wall surface of the lines and the attachments accordingly.

On the lines, in particular to the brackets of the lines may thus lead to the formation of microcracks or other damage.

Object of the present invention is therefore to provide a method by which a high-pressure fuel line is inexpensive and easy to produce, which has a structurally simple and durable connectivity to a holder.

The aforementioned object is achieved with a method for producing a high-pressure fuel line according to the features in claim 1.

Advantageous embodiments of the present method are part of the dependent claims.

• – Bereitstellung eines Rohrs,
• – zumindest abschnittsweise in Längsrichtung des Rohres vergrößern des Durchmessers zur Herstellung eines Aufnahmeabschnittes durch Stauchrundkneten,
• – Aufpressen eines Halters auf den Aufnahmeabschnitt.

The method according to the invention for producing a high-pressure fuel line, wherein a holder is coupled to the high-pressure fuel line, is characterized by the following method steps:

• - provision of a pipe,
• At least in sections, in the longitudinal direction of the tube, increase the diameter for producing a receiving section by upset kneading,
• - Pressing a holder on the receiving section.

In the context of the invention, therefore, a high-pressure fuel line is provided, which is coupled in particular as a direct high-pressure fuel line to an internal combustion engine via a holder with this. In the context of the invention, it is then possible for each of the high-pressure fuel lines to emanate supply and discharge lines that supply fuel injectors connected thereto via a high pressure.

For the production according to the invention a pipe is provided, which is a pipe that can withstand the expected pressures of up to more than 200 MPa without bursting or suffering any other damage. This can be a seamless tube or else a longitudinally welded tube.

The tube has, in particular, a length between 10 and 100 cm, very particularly preferably between 10 and 70 cm, so that it can be mounted in the region of a cylinder head of an internal combustion engine and brought into connection with fuel injectors.

The pipe provided is machined in its longitudinal direction at least in sections according to the invention by a Stauchrundknetvorgang so that its outer diameter is increased to produce a receiving portion. In the context of the invention, this can be an enlargement of the outside diameter at a substantially constant wall thickness or, alternatively, an increase in the wall thickness with a constant inside diameter, so that the outside diameter increases as a result.

Subsequently, a holder with an opening is pressed onto the receiving portion, so that a positive connection between the holder and the receiving portion is made. The holder itself is then in turn used to establish a fixed distance to an internal combustion engine and to be positively coupled at a free end to the internal combustion engine. The holder is most preferably a metallic holder made by a casting process, ie a casting holder.

The upsetting round-kneading method according to the invention is preferably carried out on a upsetting round kneading apparatus such that radially circumferentially distributed upset kneading tools are moved forwards and backwards in a pulsating radial direction to a common center, wherein the tube enclosed radially thereof is processed by forming technology. The tube is thereby pushed even in its longitudinal direction pulsating or continuously through the Stauchrundknetvorrichtung, in particular in the context of the invention, a counter-mandrel and an inner mandrel within the Pipe are arranged. Due to the counter-holder mandrel, such a compression takes place that a flow of the material is brought about in such a way that the wall thickness increases locally and the outside diameter increases and / or the outside diameter increases while the wall thickness remains substantially constant. Further preferably, the outer circumferential surface of the receiving portion is formed as a polygon and / or toothing.

In the case of a polygon, it is an outer circumferential surface in the form of a polygon, wherein the contour of the polygon is also introduced by the Stauchrundknetwerkzeug. For example, a 12-, 20- or 30-sided polygon is formed, wherein the respective corners are connected by flat sections. In particular, the upset circular kneading process hereby makes possible the largely free design of the outer circumferential surface of the receiving section with respect to a substantially circular outer circumferential surface of the starting tube.

In the case of a toothing is a corresponding outer profiling, which is applied to the receiving portion by the Stauchrundknetvorgang. In the context of the invention, however, it is also possible to interlock the surface again on the polygon section.

Furthermore, particularly preferably, the tube is heated in sections, preferably at the longitudinal section which is formed into the receiving section, in particular by an induction coil. The induction coil is in particular connected upstream of the upset circular kneading process in the direction of insertion of the tube, so that when passing through the section which is to be converted into a receiving section, local heating by the induction coil can be brought about. This results in an area with a reduced yield stress, which favors the subsequent upsetting rounding process.

In the context of the invention, it is also possible to completely compensate the entire tube after completion of the Stauchrundknetvorganges, for example, completely heat treat, so that a uniform state of stress is produced within the material of the entire tube.

In particular, the heating takes place at a temperature between 50 and 200 degrees Celsius, wherein a yield stress between 200 and 400 MPa, in particular between 250 and 350 MPa and particularly preferably of about 300 MPa is generated. In particular, a steel material is used, especially the steel material 1.4301 or 1.4307.

As a result of the at least local thickening of the receiving section, an interference fit, ie an interference fit, is thus produced with the holder, in particular the casting holder, when the casting holder is pressed on. This means that an inner circumferential surface of the holder always, even taking into account the production tolerances has a smaller diameter than the outer circumferential surface of the receiving portion. In the case of a polygonal receiving portion of the outer diameter is chosen in particular such that it includes a circle as the corners of the polygon. As a result, an interference fit between the substantially corners of the polygon and the inner circumferential surface of the casting holder is then produced.

Further preferably, the receiving portion is thermally joined to the Gußhalter, preferably by a soldering process. Thus, a holder is provided with particularly high strength, which produces a secure and durable connection by the positive fit of the interference fit, on the other hand by the material connection of the thermal joining process, in particular the soldering process. Such a connection is insensitive to the pressure pulsations occurring in the high-pressure fuel line.

Furthermore, particularly preferably, at least one intermediate space is formed between an inner lateral surface of the opening of the holder and the outer lateral surface of the receiving section, wherein the solder of the soldering process flows into the intermediate space and produces a material connection between inner lateral surface and outer lateral surface. In the context of the invention, the intermediate space is repeatedly formed, in particular when the receiving section is designed as a polygon and corresponding circular inner lateral surface of the holder, so that solder can flow radially in the intermediate spaces.

In the context of the invention, it is also possible aufzuschrupfen the holder, for example, by thermal treatment of the receiving portion. In this case, the holder is heated at least in the region of the opening, so that it widens and cools down after being placed on the receiving portion, so that the interference fit is produced.

Furthermore, in the context of the invention, a radius is formed particularly preferably in a transition between outer circumferential surface of the tube and outer lateral surface of the receiving section, or a flowing transition is formed, so that here a reduction of the locally occurring voltage peaks occurs. The outer circumferential surface between receiving portion and tube is thus durable durable against the formation of Microcracks formed as it is the case with an outer circumferential surface, which experiences a sudden change in the outer radius.

In the context of the invention, the high-pressure fuel line thus produced can then be coupled with other attachments. For example, can be soldered to the fuel line, which are used for coupling with a fuel injector within the scope of the invention.

The aforementioned method steps can be combined with one another in the context of the invention as desired, with the associated advantages.

Further advantages, features, characteristics and aspects of the present invention are part of the following description. Preferred embodiments are shown in the schematic figures. These are for easy understanding of the invention. Show it:

1 a high-pressure fuel line according to the invention in a perspective view,

2 a longitudinal section of a high-pressure fuel line according to the invention with a receiving section,

3 a cross section through the high pressure fuel line according to Schnittline III-III and

4 a cross section through an inventive high-pressure fuel pipe during manufacture.

In the figures, the same reference numerals are used for the same or similar components, even if a repeated description is omitted for reasons of simplicity.

1 shows a high-pressure fuel line according to the invention 1 , wherein the fuel line from a fuel pipe 2 as well as on the fuel pipe 2 trained connecting piece 3 is designed for coupling with injectors, not shown. Furthermore, the fuel pipe 2 a return pipe 4 on, flows back through the unused fuel to a fuel tank, not shown. Also is an inlet nozzle 5 formed, which is connectable to a fuel line not shown for supplying the fuel. At the fuel pipe 2 are holders according to the invention 6 attached by means of mounting holes 7 be coupled to a cylinder head of an internal combustion engine, not shown.

2 shows a perspective view of the fuel pipe according to the invention 2 , where the fuel pipe 2 in its longitudinal direction 8th a length section 9 has, in its outer diameter D9 with respect to the outer diameter D2 of the fuel pipe 2 is formed enlarged. This length section 9 is as a recording section 10 formed, wherein the receiving portion 10 is designed as a polygon in the variant shown here. On the recording section 10 is a ring 11 of the owner 6 placed by means of an interference fit, so that a positive coupling between an inner circumferential surface 13 an opening 12 of the ring 11 and an outer circumferential surface 14 the receiving portion is formed.

3 shows a cross section along the section line III-III 2 , wherein it can be seen here that the inner circumferential surface 13 of the ring 11 with the outer circumferential surface 14 of the receiving section 10 positively coupled, wherein the positive connection between the inner circumferential surface 13 as well as the corners 15 is formed of the polygon. In the intervals 16 remain slit-like openings that extend in the longitudinal direction. In this slot-like openings can be introduced by a non-illustrated thermal joining process, such as a soldering a solder, which then has an additional material connection between the outer surface 14 of the receiving section 10 and inner surface 13 of the ring 11 formed.

4 shows in extracts an inventive manufacturing method in which the fuel pipe 2 through an induction coil 17 through in a direction of insertion 18 in a swaging machine 19 is introduced. The end 20 of the fuel pipe 2 is thereby by a Gegenhalterdorn 21 against the insertion direction 18 countered and by an internal spine 22 becomes the pipe 2 prevented by the forming process to reduce an inner diameter Di. The outer diameter of the length section 9 that is to the receiving section 10 is converted to the outer diameter D9 by increasing the wall thickness W9 in the region of the receiving portion 10 increased, compared to an outer diameter D2 of the remaining fuel pipe 2 and a wall thickness W2 also the legal fuel pipe 2 , The swaging machine 19 has circumferential upsetting tools 23 auf, which are exemplarily represented as two tools that a pulsating kneading movement in the translational direction 24 carry out. In this case, according to the invention, not only the outer diameter D9 can be widened, but also corresponding outer circumferential surfaces 14 be made with profilings, for example in the form of a polygon by the Stauchrundknetvorgang.

Furthermore, in 4 to recognize that in a transition region Ü a radius is formed, so that from the outer diameter D2 to the outer diameter D9, a flowing transition takes place, in the case of occurring stresses within the wall thickness W of the tube 2 leads to a surge in voltage.

LIST OF REFERENCE NUMBERS

1

High-pressure fuel line

2

Fuel pipe

3

spigot

4

Return connectors

5

inlet port

6

holder

7

mounting hole

8th

Longitudinal direction too 2

9

longitudinal section

10

receiving portion

11

Ring too 6

12

Opening to 11

13

Inner jacket surface too 12

14

Outer jacket surface too 10

15

corner

16

gap

17

induction coil

18

insertion direction

19

Stauchrundknetvorrichtung

20

End to 2

21

Backstop Dorn

22

inner mandrel

23

Stauchrundknetwerkzeug

24

translational direction

W2

Wall thickness too 2

W9

Wall thickness too 9

D2

Outside diameter too 2

D9

Outside diameter too 9

di

Inner diameter

Ü

Transition area

Claims (9)

Method for producing a high-pressure fuel line ( 1 ), with a holder ( 6 ) with the high-pressure fuel line ( 1 ), characterized by the following process steps: providing a tube, at least in sections in the longitudinal direction of the tube increasing the outside diameter ( 14 ) for producing a receiving section ( 10 ) by swaging circular kneading, - pressing a holder ( 6 ) on the receiving section ( 10 ). Method according to claim 1, characterized in that in the receiving section ( 10 ) The wall thickness (W9) is thickened or the outer diameter (D9) is increased at a substantially constant wall thickness. Method according to claim 1 or 2, characterized in that the outer circumferential surface ( 14 ) of the receiving section ( 10 ) is formed as a polygon and / or toothing. Method according to one of the preceding claims, characterized in that the pipe sections, preferably at the longitudinal section ( 9 ) leading to the receiving section ( 10 ) is heated, in particular by an induction coil ( 17 ). A method according to claim 4, characterized in that a heating to a temperature between 50 and 200 degrees Celsius is made. Method according to one of the preceding claims, characterized in that between the holder ( 6 ) and the receiving section ( 10 ) an interference fit is formed, wherein the holder ( 6 ) with an opening ( 12 ) on the receiving section ( 10 ) is pressed. Method according to claim 7 or 8, characterized in that the holder ( 6 ) with the receiving section ( 10 ) is thermally joined, preferably by a soldering process. Method according to one of the preceding claims, characterized in that between an inner circumferential surface ( 13 ) of the opening ( 12 ) and the outer circumferential surface ( 14 ) of the receiving section ( 10 ) at least one intermediate space ( 16 ), in particular solder into the space ( 16 ) flows. Method according to one of the preceding claims, characterized in that in a transition between pipe and receiving portion ( 10 ) A radius is formed.

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