EP3303872A1

EP3303872A1 - Pressure container, in particular for a cylinder unit

Info

Publication number: EP3303872A1
Application number: EP16721733.0A
Authority: EP
Inventors: Holger Kirchner; Thomas Meyer; Norbert Ackermann
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2015-05-26
Filing date: 2016-04-25
Publication date: 2018-04-11
Also published as: DE102015209562A1; WO2016188687A1

Abstract

The invention relates to a pressure container having a multi-layered enveloping body and a filling body, wherein the temperature resistance can be increased by an adaptation of the materials of the enveloping body and the filling body.

Description

Pressure vessel, in particular for a cylinder unit

The invention relates to a pressure vessel according to the preamble of claim 1.

Enclosed gas masses are u. a. Used where a medium is to be pressurized and held, but must not be mixed with an open pressure fluid. A common application is in piston-cylinder units such as vibration dampers. Such a vibration damper with an enclosed gas mass is known for example from US 3,294,391. The enclosed gas mass serves to compensate for the volume of the plunger rod or the plunger immersed in the vibration damper.

A problem with such an enclosed gas mass is the fact that the gas diffuses from the enveloping body into the damping medium of the vibration damper through the wall of the enveloping body. If a certain gas outlet is reached, it is z. B. the vibration damper in its function or even disabled. One way to reduce the described malfunction is to use certain filling gases such as nitrogen. But also nitrogen diffuses through the usual enveloping body, which often consist of a rubber material or elastomer, especially at higher temperatures.

DE 98 35 222 A1 describes a pressure vessel which is filled with at least one medium which is prestressed by a gas mass trapped in a shape-variable enveloping body, in particular for compensating the volume in a vibration damper, comprising a wall in which one is under pressure the gas is enclosed, wherein the wall of the enveloping body is at least partially formed of a gas-tight barrier layer and the wall is constructed in multiple layers.

The enveloping body should be as flexible as possible. For a thin metal foil is used. To compensate for the reduced strength of the metal foil is a support layer is used, which is assigned to the metal foil. The base course is between see the metal foil and the inner material layer arranged. The internal material layer is required, inter alia, for the welding process. Possible materials are, for example, PE, PP and PA in question. In this case, the support layer can serve as a protective layer for the metal foil. For welding, a seal welding method is proposed.

In the welded edge of the envelope a filler is inserted, such. B. from DE10 2004 005 196 B4 is known. Therein, the weldability of the filling body with the enveloping body is achieved primarily via a special shaping of the filling body in the area of the contact surface with the edge of the body.

The object of the present invention is to realize a pressure vessel which has sufficient strength even at higher temperatures.

The object is solved by the features of patent claim 1.

With reference to the following figures, the invention will be explained in more detail.

Fig. 1 overall view of a pressure vessel

Fig. 2 filler as a single part

Fig. 3 sectional view through the pressure vessel in the region of the packing

Fig. 4 detail view to Fig. 3rd

FIG. 1 shows in simplified form a pressure vessel 1, as it is known, for example, from FIG. B. is used in a memory or compensation room. An exemplary application consists in a piston-cylinder unit in a chassis as a vibration damper or as Verstellaggregat to adjust the level of a vehicle body static or dynamic.

The pressure vessel 1 comprises an enveloping body 3 and a filling body 5. The filling body 5 has a filling connection 7 to a gas filling system and a connection region 9, which is inserted in a peripheral edge 11 of the enveloping body. Dash-dotted lines extending in the longitudinal direction of the filling body are available for bending line 13 of the pressure vessel. 1 The peripheral edge 1 1 is formed by a welding area, which also covers the connection area 9 of the filling body 5.

For better understanding, the filler 5 is shown in Figure 2 in perspective view.

From the combination of Figures 3 and 4 it can be seen how the filler 5 is inserted into the enveloping body 3 and is in contact with an inner layer 1 1 envelope 3. The wall of the enveloping body 3 is executed in four layers in this case. The innermost layer 1 1 is formed by a plastic film, which is optimized in terms of weldability. Preferably, a so-called blend is used, for. B. a plastic-material mixture of PA6 and PA66. The advantage is that this combination of materials is on the one hand particularly suitable for films and has a melting point which is higher than peak temperatures in a piston-cylinder unit.

A second film 17 of the enveloping body 3 is formed by a metallic material, for. As aluminum. Between the different foils 15; 17 is preferably carried out an adhesive layer. The metallic foil 17 effectively prevents the passage of gas from inside the pressure vessel 1.

A third film 19 is formed by a polyamide which is stretched in at least one direction to reduce the elongation of the material. This so-called oriented polyamide forms a mechanical support layer for the metal foil 17. Support layer is to be understood in the sense that a strain load, the z. B. starting from the inner welding film 15 is received by the support layer 19, so that the metal layer 17 is under no circumstances overloaded.

An outer film 21 is also preferably formed of polyamide and serves as a protective layer against the operating temperature on the outside of the pressure vessel 1, but also as a mechanical protective layer, for. B. due to a frictional load between the outer layer 21 and a pressure vessel receiving rigid container. The filler 5 is also made of polyamide or copolyamide or copolymer.

The idea is that the inner film 15, which forms the welded connection and whose material selection is designed for the production of films, thus a comparatively tough base material preferred. The filler 5, which is produced by means of a spraying process, should preferably consist of an easily flowing base material so that the spraying process takes place optimally and an injection mold is only exposed to a comparatively low load.

On the other hand, the materials for the filling body 5 and the inner film 15 are made of plastics, which have a comparable melting point. With the material combination of the filler 5 and the inner film 15 described above, this goal is achieved. Since both materials are based on a polyamide, the melting point of both materials is above about 130 ° C, the maximum operating temperature of the piston-cylinder unit.

The welding area 1 1 is generated by an ultrasonic welding process. For this purpose, the filler has over Anschmelzstege 23, which extend in the longitudinal direction of the weld region 1 1. This Anschmelzstege 23 serve to produce a manageable energy use a melt that connects the enveloping body 3 with the packing 5. In principle, one could do without the melt-on webs 23, but then the melt would have to be produced from the full body of the packing 5.

REFERENCE CHARACTERS

I pressure vessel

3 enveloping body

5 packings

7 filling connection

9 connection area

I I edge

13 bending line

15 inner foil

17 second slide

19 third slide

21 outer foil

23 melting points

Claims

claim

1 . Pressure vessel having a multilayer envelope body and a filler characterized by at least one feature of the description or the figures.