METHOD FOR PRODUCING A PRESSURE VESSEL

Abstract

The invention relates to a method for producing a pressure vessel (1) for storing gaseous fuels, in particular for a motor vehicle, comprising the steps of providing a support tube (2), providing a blocking tube (3) which has an outer diameter (31) which is smaller than an inner diameter (22) of the support tube (2), arranging the blocking tube (3) inside the support tube (2), and deforming the support tube (2) in such a way that an inner surface (22a) of the support tube (2) rests against an outer surface (31a) of the blocking tube (3), in order to produce a double tube (4).

Claims

1. Method for producing a pressure vessel for storing gaseous fuels, in particular for a motor vehicle, comprising the steps of: providing a support tube, providing a blocking tube which has an outer diameter which is smaller than an inner diameter of the support tube, arranging the blocking tube inside the support tube, and deforming the support tube in such a way that an inner surface of the support tube rests against an outer surface of the blocking tube, in order to produce a double tube.

2. Method according to claim 1, further comprising the step, before deforming the support tube: joint compressing of support tube and blocking tube in the radial direction at a compression portion, which is located in particular at an axial end of the two tubes.

3. Method according to claim 1, further comprising the step, after deforming the support tube: producing at least one dome-shaped end region by deforming the double tube, in particular by means of hot-spin forming.

4. Method according to claim 1, wherein deforming the support tube is effected by simultaneous radial compression and axial stretching.

5. Method according to claim 1, further comprising the step of: separating the double tube into several double tube pieces to produce several pressure vessels.

6. Method according to claim 1, wherein the blocking tube is formed from an austenitic steel.

7. Method according to claim 1, wherein the support tube is formed from a martensitic steel.

8. Method according to claim 1, wherein the blocking tube and the support tube are formed from materials with substantially the same coefficient of thermal expansion, or wherein the blocking tube is formed from a material which has a greater coefficient of thermal expansion than a material of the support tube.

9. Method according to claim 1, wherein a first wall thickness of the blocking tube is at most 80%, preferably at most 50%, particularly preferably at most 30%, of a second wall thickness of the support tube.

10. Method according to claim 1, wherein the outer diameter of the blocking tube is at most 95%, preferably at most 80%, particularly preferably at least 60%, of the inner diameter of the support tube.

11. Method according to claim 1, further comprising the step of: heat treatment of the double tube.

12. Method according to claim 11, wherein the heat treatment comprises the successive steps of: hardening, quenching, first tempering, air cooling, second tempering, air cooling.

13. Method according to claim 1, further comprising the step of: coating the double tube, in particular with an anti-corrosion coating.

14. Pressure vessel for storing gaseous fuels, in particular for a motor vehicle, produced by means of a method according to claim 1.

Description

[0058] Further details, advantages and features of the present invention result from the following description of embodiments based on the drawing. The Figures show in:

[0059] FIG. 1 a simplified schematic sectional view of a pressure vessel according to a preferred embodiment of the invention,

[0060] FIG. 2 a step of a production method of the pressure vessel of FIG. 1, and

[0061] FIG. 3 another step of the production method of the pressure vessel of FIG. 1.

[0062] With reference to FIGS. 1 to 3, a vessel 1 and a method for producing the pressure vessel according to a preferred embodiment of the invention are described below. In the figures, functional components are always marked with the same reference characters.

[0063] The pressure vessel 1 is intended for storing gaseous fuels, which can preferably be used as fuels for motor vehicles. In particular, the vessel 1 is intended for storing gaseous hydrogen under high pressure.

[0064] To produce the pressure vessel 1, a support tube 2 and a blocking tube 3 are first provided (see FIG. 2). The blocking tube 3 has an outer diameter 31 that is smaller than an inner diameter 22 of the support tube 2.

[0065] A first wall thickness 33 of the blocking tube 3 is smaller than a second wall thickness 23 of the support tube 2. Preferably, the first wall thickness 33 is at most 50% of the second wall thickness 23.

[0066] The two tubes 2 and 3 are made of steel. In detail, the blocking tube 3 is made of austenitic steel and the support tube 2 is made of martensitic steel.

[0067] Furthermore, the materials of the two tubes 2, 3 are selected in such a way that the blocking tube 3 is made of a material that has a greater coefficient of thermal expansion than a material of the support tube.

[0068] At the start of the production method, the blocking tube 3 is arranged inside the support tube 2, for example coaxially to each other as shown in FIG. 2. In this configuration, there is a gap 48 in the radial direction between the two tubes 2, 3.

[0069] The two tubes are then compressed together in this inserted configuration. Both the support tube 2 and the blocking tube 3 are deformed in the radial direction in such a way that, after deformation, an outer diameter 21 of the support tube 2 after deformation is smaller than an inner diameter 32 of the blocking tube 3 before deformation (see FIGS. 2 and 3). The compression of support tube 2 and blocking tube 3 only takes place within a compression portion 40, which is located at one axial end of the two tubes 2, 3. As a result, the blocking tube 3 and support tube 2 are held axially immobile against each other by means of the compression portion 40.

[0070] The support tube 2 is then deformed. The support tube 2 is simultaneously compressed in a radial direction (see arrows B in FIG. 2) and stretched in an axial direction (see arrows C in FIG. 2). The support tube 2 is deformed until it rests against an outer surface 31a of the blocking tube 3, preferably in such a way that a press connection is created between the support tube 2 and the blocking tube 3. A double tube 4 is thus formed from the support tube 2 and the blocking tube 3. The double tube 4 is shown in FIG. 3.

[0071] The double tube 4 is then separated into several double tube pieces 41 along the axial direction. A separate pressure vessel 1 can then be produced from each of these double tube pieces 41.

[0072] To produce the pressure vessel 1, a dome-shaped end region 45 and a connection region 46 are then produced at each axial end of the double tube piece 41 (see FIG. 1).

[0073] The dome-shaped end region 45 forms a dome-shaped taper of the inner and outer contour of the double tube piece 41, which opens into the connection region 46. The connection region 46 is formed as a straight tubular end piece of the pressure vessel 1.

[0074] To produce the dome-shaped end region 45 and the connection region 46, the corresponding double tube piece 41 is deformed radially inwards in certain areas using a pressure forming process, preferably hot-spin forming.

[0075] Subsequently, an internal thread 47 can be formed on the inner circumference of each of the connection regions 46, by means of which, for example, a connection member 49 can be connected to the pressure vessel 1. By means of the connection member 49, for example, an inner cavity 5 of the pressure vessel, in which the gaseous fuel can be stored under pressure, can be brought into fluid connection with a line via which the gaseous fuels can be transported further, for example to a consumer. At the connection region 46 opposite the connection member 49, for example, a closure element can be provided in order to close the cavity 5 at this end of the pressure vessel 1 in a fluid-tight manner.

LIST OF REFERENCE CHARACTERS

[0076] 1 pressure vessel [0077] 2 support tube [0078] 3 blocking tube [0079] 4 double tube [0080] 5 cavity [0081] 21 outer diameter of support tube [0082] 22 inner diameter of support tube [0083] 22a inner surface of support tube [0084] 23 second wall thickness of support tube [0085] 31 outer diameter of blocking tube [0086] 32 inner diameter of blocking tube [0087] 32a outer surface of blocking tube [0088] 33 first wall thickness of blocking tube [0089] 40 compression portion [0090] 41 double tube pieces [0091] 45 dome-shaped end region [0092] 46 connection region [0093] 47 internal thread [0094] 48 gap [0095] 49 connection member