CH634634A5 - METHOD FOR PRODUCING A FUEL PRESSURE PIPE. - Google Patents

Description

The invention relates to a method for producing a fuel pressure line with a pressure pipe and a casing pipe, which is supported on the pressure pipe by means of openings for the leakage fuel return having spacing means.

From DE-Gbm 76 38 072 a fuel pressure line of an internal combustion engine is already known, which is produced by using a commercially available precision tube, around which a spiral made of metal is wound as a spacer material for the casing tube.

However, they are no longer suitable for use in self-igniting internal combustion engines, which require extremely high injection pressures of up to 1300 bar due to the ever higher supercharging, since the surface structure of the inner and outer walls of such precision tubes is not kept free of cracks and wrinkles due to their manufacturing process can. At the high pulsating injection pressures mentioned, the fatigue strength is thus greatly reduced, and also a firm support of the spacing material on the fuel pressure pipe is no longer guaranteed, so that there is a risk of fraying.

Accordingly, the object of the invention is to create a fuel pressure line which can withstand extremely high injection pressures with high operational reliability.

This object is achieved in that the pressure pipe is machined from solid material, the outer surface of which is processed to form alternating sections of larger and smaller outside diameters, and the grooves connecting the two adjacent sections of smaller outside diameter are machined into the sections of larger outside diameter and then the jacket pipe is pulled over the fuel pressure pipe.

Another advantage of these measures is that the choice of materials and dimensions of the pipes is not limited to the values of commercially available pipes, so that the fuel pressure pipe can be optimally configured according to the given material selection, dimensions and surface quality Can design company sizes.

Advantageously, sections with a larger outside diameter are provided with external threads at the two ends of the fuel pressure pipe. The effect of thread grooves that represent notches can thereby be prevented. The fatigue strength of the connection points is not affected.

A section with a larger outside diameter is expediently arranged at the beginning and at the end of a bend in the fuel pressure line on the pressure pipe, which makes it possible to bend the fuel pressure pipe with the coated jacket pipe as a complete unit on a bending machine, the beginning and end of each Portions of larger diameter arranged at the end of a bend represent clamping points.

Further advantages and features emerge from the following description with reference to the drawing in conjunction with the claims.

The drawing shows part of an embodiment of the fuel pressure line, which is shown in the area of a bend and in the connection area to an injection pump in half section.

The fuel pressure line 1 consists of a pressure pipe 2 and a casing pipe 3. The pressure pipe 2 has sections 4 of larger diameter arranged at axial intervals, on which the casing pipe 3 rests with the formation of cavities 5. The cavities 5 enclosed by the pressure pipe 2 and the casing pipe 3 are connected to one another by means of grooves 6 machined in the sections 4.

In each case at the end regions of the fuel pressure line 1, of which the end connected to an injection pump (not shown) is shown in the drawing, the pressure pipe 2 has a section 8 of larger diameter provided with an external thread 7.

The section 8 is screwed via an internal thread 9 to a union nut 10, which is connected via a further internal thread 11 to a connecting piece 12 of an injection pump.

End section 13 of pressure pipe 2 adjoins section 8 and rests sealingly on connecting piece 12 of the injection pump.

In the upper and lower area, the union nut 10 each has a hollow cylindrical part 14 or 15, with which it rests sealingly on the one hand on the outer surface of the casing tube 3 and on the other hand on a cylindrical surface of the connecting piece 12.

The space 16 located between the two internal threads 9 and 11 is in connection via axially parallel bores 17 with the upper hollow cylindrical part 14 and the cavities 5 for leakage fuel return.

The pressure pipe 2 of the fuel line 1 is worked from the full. The bore is produced by machining the already heat-treated material, the inner surface of the bore being able to be produced with the surface quality required for extremely high pressure loads, i. H. with a surface that does not have any fatigue-reducing notches, such as cracks and folds.

Following the drilling, the outer surface is produced by machining, with deviations of the

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634 634

Bore from the axis of the blank can still be corrected. The sections 4 with a larger outer diameter serve as Lynettenstellen. After the external thread 7 has been cut into the sections 8 at the end regions of the pressure pipe 2 and the grooves 6 have been milled into the sections 4 of larger diameter, the casing pipe 3 is drawn on, which comes to rest firmly on the sections of larger diameter. The unit consisting of the pressure pipe 2 and the casing pipe 3 is then provided with the bends, the sections 4 of larger diameter formed at the beginning and at the end of a bend representing clamping points.

The unit 5 consisting of pressure pipe 2 and casing pipe 3 ensures high operational reliability even at extremely high pulsating injection pressures, since on the one hand there are no notches on the pipe surfaces and on the connection points and on the other hand no friction points can be formed by moving parts.

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1 page drawings

Claims (5)

634 634 1. A method for producing a fuel pressure line with a pressure pipe and a jacket pipe, which is worn by means of an opening for the leakage fuel return spacer means on the pressure pipe, characterized in that the pressure pipe (2) is produced by machining from solid material, the outer surface of which Formation of alternating sections of larger and smaller outside diameter is processed and into the sections (4) of larger outside diameter the two adjacent sections of smaller outside diameter connecting grooves (6) are worked in and then the casing tube (3) is pulled over the pressure pipe (2). 2. The method according to claim 1, characterized in that at the two ends of the pressure pipe (2) sections (8) with a larger outside diameter are provided with external threads (7). 2nd PATENT CLAIMS 3. The method according to claim 1, characterized in that at the beginning and at the end of a bend in the fuel pressure line (1) on the pressure pipe (2), a section (4) with a larger outside diameter is produced. 4. Fuel pressure line, produced by the method according to one of the preceding claims, characterized in that the pressure pipe (2), the spacing means in the form of a number of axially spaced sections (4) with a larger outside diameter, in which the adjacent sections with a smaller outside diameter connecting grooves (6) are incorporated, and sections (8) provided with external threads (7) form an integral part at the ends of the pressure pipe (2), onto which the casing pipe (3) is fitted. 5. Fuel pressure line according to claim 4, characterized in that at the beginning and at the end of a bend in the fuel pressure line (17) on the pressure pipe (2) a section (4) with a larger outside diameter is arranged.