US-12618525-B2 - Pressure tank for gas-operated vehicle

US12618525B2US 12618525 B2US12618525 B2US 12618525B2US-12618525-B2

Abstract

A pressure tank for storing gas, for mounting in a gas-operated vehicle. The pressure tank has a rotationally symmetrical, elongate shape which is cylindrical in the central region and is closed at both ends by curved polar caps, and a wall which surrounds a hollow space for storing the gas. At each of the polar caps, the pressure tank has a metallic connection piece, a so-called boss. The wall has a reinforcing layer made from fiber-reinforced plastic and an inner liner for sealing purposes. For sealing purposes, a bush is connected to the boss. A pressure ring and a spring element are configured in such a way that the spring element is supported on the bush and presses the pressure ring against the liner and, as a result, presses the liner in a region against the boss.

Inventors

Mark Bleischwitz
Thomas Lanzl
Jürgen Brühler
Gordej Klein

Assignees

VOITH PATENT GMBH

Dates

Publication Date: 20260505
Application Date: 20211215
Priority Date: 20201222

Claims (19)

1 . A pressure tank for storing gas and for assembly in a gas-operated vehicle, the pressure tank comprising: a rotationally symmetrical elongate form having a central region with a cylindrical shape and two ends that are closed off with curved pole caps, and having a wall enclosing a hollow space for storing the gas; a metal connection piece, being a boss, on each of said pole caps; said wall including a reinforcement layer made of fiber-reinforced plastics material and an inner liner for sealing; a bush connected to said boss; a rigid pressure ring; a resilient element; said liner being disposed between the bush to boss connection and said pressure ring along a longitudinal axis L of the pressure tank; said resilient element being supported on said bush between said pressure ring and said bush and configured to press said pressure ring onto said liner and thus to press said liner onto said boss; and said pressure ring together with said bush completely surrounding said resilient element.
2 . The pressure tank according to claim 1 , wherein said resilient element is configured to orient a resilient force for pressing in a direction that is substantially parallel with the longitudinal axis L of the pressure tank or encloses with the longitudinal axis L of the pressure tank an angle of no more than a maximum of ±20°.
3 . The pressure tank according to claim 1 , wherein said pressure ring touches said liner with a face that is orientated substantially perpendicular to the longitudinal axis L of the pressure tank or that encloses an angle with respect to the longitudinal axis L of between 70° and 110°.
4 . The pressure tank according to claim 1 , wherein said resilient element is a cup spring.
5 . The pressure tank according to claim 1 , wherein said bush is secured to said boss by way of a screw thread, to enable a resilient force by which said pressure ring is pressed against said liner to be changed.
6 . The pressure tank according to claim 1 , wherein said bush has a collar on which said resilient element is supported, and said collar is oriented substantially perpendicularly to the longitudinal axis L of the pressure tank.
7 . The pressure tank according to claim 1 , wherein said boss has an outer thread in contact with a mating inner thread of said liner and arranged concentrically relative to the longitudinal axis L of the pressure tank.
8 . The pressure tank according to claim 1 , wherein a face of said pressure ring that is pressed onto said liner extends in a radial direction R at least 20 mm.
9 . The pressure tank according to claim 1 , wherein said boss is formed with projections in a region of said boss at which said liner is pressed onto said boss by said pressure ring, said projections having a height between 0.3 mm and 1.5 mm.
10 . The pressure tank according to claim 1 , wherein said pressure ring is displaceable relative to said bush in a direction of the longitudinal axis L of the pressure tank.
11 . The pressure tank according to claim 10 , wherein at least one of said pressure ring and said bush is formed with a stop configured to enable a rigid force transmission between said pressure ring and said bush in the direction of the longitudinal axis L via said resilient element when said resilient element is completely compressed.
12 . A pressure tank for storing gas and for assembly in a gas-operated vehicle, the pressure tank comprising: a rotationally symmetrical elongate form having a central region with a cylindrical shape and two ends that are closed off with curved pole caps, and having a wall enclosing a hollow space for storing the gas; a metal connection piece, being a boss, on each of said pole caps; said wall including a reinforcement layer made of fiber-reinforced plastics material and an inner liner for sealing; a bush connected to said boss; a rigid pressure ring; a resilient element; said liner being disposed between the bush to boss connection and said pressure ring along a longitudinal axis L of the pressure tank; said resilient element being supported on said bush between said pressure ring and said bush and configured to press said pressure ring onto said liner and thus to press said liner onto said boss; said pressure ring being displaceable relative to said bush in a direction of the longitudinal axis L of the pressure tank; and at least one of said pressure ring or said bush being formed with a stop configured to transmit a force between said pressure ring and said bush in the direction of the longitudinal axis L directly via the stop when said resilient element is compressed to a sufficient degree.
13 . A method for producing a pressure tank according to claim 1 , the method comprising: constructing the wall of the pressure tank and performing a blow-molding process to form the liner that surrounds the hollow space for storing the gas; arranging the bush to be connected to the boss, the rigid pressure ring, and the resilient element on a blow pin, while the liner is being produced with the blow-molding process such that the pressure ring and the resilient element are located, after the liner has been produced, on an inner side of the liner, wherein the resilient element can be supported on the bush and can press the pressure ring onto the liner and can press the liner onto a face of the boss when the bush is connected to the boss.
14 . The method according to claim 13 , which comprises, during the blow-molding process, displacing the pressure ring so far in a direction of a longitudinal axis of the pressure tank relative to the bush that the pressure ring compresses the resilient element so that a stop on the bush comes into direct contact with the pressure ring and/or a stop on the pressure ring comes into direct contact with the bush for force transmission.
15 . The method according to claim 13 , which further comprises connecting the boss to the liner and to the bush, connecting the boss and the bush by screwing the boss onto an outer thread of the bush, and screwing the boss so far onto the bush that the pressure ring is displaced in the direction of the longitudinal axis L relative to the bush and that the pressure ring compresses the resilient element until, for force transmission, a stop on the bush comes into direct contact with a counter-face on the pressure ring and/or a stop on the pressure ring comes into direct contact with a respective counter-face on the bush.
16 . The method according to claim 13 , which comprises, during the blow-molding process, displacing the pressure ring so far in the direction of the longitudinal axis L relative to the bush to completely compress the resilient element and to effect a rigid force transmission between the bush and the pressure ring via the resilient element.
17 . The method according to claim 16 , wherein the rigid force transmission is effected through a stop on the pressure ring and/or a stop on the bush.
18 . The method according to claim 13 , which further comprises connecting the boss to the liner and to the bush by screwing the boss onto an outer thread of the bush, and thereby screwing the boss so far onto the bush that the pressure ring is displaced in a direction of the longitudinal axis L relative to the bush and the pressure ring compresses the resilient element completely until a rigid force transmission between the bush and the pressure ring is effected via the resilient element.
19 . The method according to claim 18 , wherein the rigid force transmission further comprises connecting the boss to the liner and to the bush via a stop on the pressure ring and/or a stop on the bush.

Description

FIELD AND BACKGROUND OF THE INVENTION The invention relates to a pressure tank for storing gas for assembly in a gas-operated vehicle, wherein the pressure tank has a rotationally symmetrical elongate form which is cylindrical in the central region and which is closed at both ends with curved pole caps. The pressure tank has a wall which surrounds a hollow space for storing the gas and a metal connection piece, a so-called boss, on each of the pole caps, wherein the wall comprises a reinforcement layer made of fiber-reinforced plastics material and an inner liner for sealing. The invention further relates to a method for producing such a pressure tank or a pre-product for such a pressure tank, wherein for the structure of the wall of the pressure tank a liner which surrounds the hollow space for storing the gas is produced in a blow-molding method. Gas-operated vehicles have, for example, a gas motor or a fuel cell with an electric motor as a drive. In order to be able to store sufficient fuel, the gas which may inter alia be hydrogen is stored under high pressure in the tank. Typical for such pressure tanks are pressures of over 200 bar, often up to 600 bar and sometimes even up to 700 or 800 bar. This means that not only must the pressure tank be gas-tight under this pressure, but also that it requires a high level of mechanical stability. In the prior art, pressure tanks for gas-operated vehicles are known. These pressure tanks have a wall which for sealing comprises an inner liner, for example, made of thermoplastic material, and in order to provide the mechanical stability comprises a reinforcement layer made of fiber-reinforced plastics material. Preferably, the reinforcement layer is wound and configured as a CFRP layer. CFRP stands for carbon-fiber-reinforced plastics material. The boss has a through-hole and a connection thread. In at least one of the two bosses, a tank fitting which enables the pressure tank to be filled or gas to be removed in a controlled manner is connected. On the other boss, the through-opening is sealed with a closure or another tank fitting or a safety valve is provided at that location. Particular attention must be paid with such pressure tanks to the connection between the metal connection piece, the boss, and the liner since in this instance particularly good sealing is required, including under mechanical loading, with changing internal pressure or with significant temperature fluctuations. In particular with hydrogen tanks, this is a significant challenge. DE 10 2014009343A1 describes a pressure tank which has the above-mentioned features. In order to improve the sealing, a clamping sleeve is provided at that location between the reinforcement layer and liner. The clamping sleeve should transmit external loads acting via the boss to the reinforcement layer and thus protect the liner from overloading which can lead to leakage. DE 102010021667 A1 provides a sealing ring between the boss and liner which is intended to ensure the sealing. In DE 102016219638 A1 a sealing ring is pressed by means of a locking sleeve into a gap between the boss and liner in order to achieve a sealing between the liner and boss. However, the configurations according to the prior art have the disadvantage that they do not act sufficiently well against changing loads, whether it be as a result of temperature fluctuations or as a result of changing pressure loads, and thus also do not ensure any durable sealing. A good and lasting sealing is, however, particularly important with larger pressure tanks particularly for hydrogen, as required, for example, for utility vehicles which are driven with a fuel cell. Such pressure tanks may reach diameters of up to 600 mm and lengths of 2500 mm. Previously known sealing concepts are not sufficient in this instance. SUMMARY OF THE INVENTION The object of the invention is to develop a pressure tank which has better sealing and a long service-life with a low level of leakage and to set out a method in which such pressure tanks can be produced in a simple and reliable manner. The object is achieved, on the one hand, by a pressure tank as claimed. Advantageous features are set out in the respective dependent claims. According to the invention, the pressure tank as claimed is characterized in that for sealing a bush which is connected to the boss, a pressure ring and a resilient element are provided and configured in such a manner that the resilient element is supported on the bush and presses the pressure ring onto the liner and thereby presses the liner in a region onto the boss. This region is a face and is preferably in the form of an annular face. A significant advantage of the embodiment according to the invention involves, as a result of the resilient element and as a result of the two-part configuration with a bush and a pressure ring, a pretensioning being able to be applied to the sealing face between the liner and boss for sealing. The sealing face is