DE102015223263A1 - Cryogenic pressure vessel - Google Patents

Abstract

The technology disclosed here relates to a cryogenic pressure vessel 40 for a motor vehicle having an inner container 10 and an outer container 30. Between the inner container 10 and the outer container 30, an evacuated space V is arranged at least in regions. The inner container 10 has a plastic material layer 14. Between the plastic material layer 14 and the evacuated space V is at least partially a barrier layer 16 is arranged. The barrier layer 16 is formed and arranged such that it at least reduces the transition of escaping from the plastic material layer 14 constituents in the evacuated space V, wherein between the barrier layer 16 and the plastic material layer 14 at least partially a gap is formed, and wherein the barrier layer 16 at least partially surrounded by a cover layer 18.

Description

The technology disclosed herein relates to a cryogenic pressure vessel.

Cryogenic pressure vessels are known in the art. Such a pressure vessel comprises an inner container and an outer container surrounding it to form an evacuated (intermediate) space. Cryogenic pressure vessels are used, for example, for motor vehicles, in which a gaseous fuel under ambient conditions is cryogenically stored and thus essentially in the liquid or supercritical state of aggregation with respect to the ambient conditions of significantly higher density.

For example, the EP 1 546 601 B1 such a cryogenic pressure vessel. The DE 10 2015 213 563 A1 The applicant discloses a container with a metal or ceramic coating.

It is an object of the technology disclosed herein to improve a cryogenic pressure vessel or to provide an alternative embodiment. The object is solved by the subject matter of the independent claims. The dependent claims are preferred embodiments.

The technology disclosed herein relates to a cryogenic pressure vessel for a motor vehicle. The cryogenic pressure vessel may store fuel in the liquid or supercritical state. A supercritical state of aggregation is a thermodynamic state of a substance which has a higher temperature and a higher pressure than the critical point. The critical point denotes the thermodynamic state in which the densities of gas and liquid of the substance coincide, that is, it is single-phase. While one end of the vapor pressure curve in a pT diagram is marked by the triple point, the critical point represents the other end. For hydrogen, the critical point is 33.18 K and 13.0 bar. A cryogenic pressure vessel is particularly suitable for storing the fuel at temperatures significantly below the operating temperature (meaning the temperature range of the vehicle environment in which the vehicle is to be operated) of the motor vehicle, for example at least 50 Kelvin, preferably at least 100 Kelvin or At least 150 Kelvin below the operating temperature of the motor vehicle (usually about -40 ° C to about + 85 ° C). The fuel may be, for example, hydrogen, which is stored at temperatures of about 34 K to 360 K in the cryogenic pressure vessel. The pressure vessel can be used in a motor vehicle which is operated, for example, with compressed natural gas (CNG) or liquefied natural gas (LNG). The cryogenic pressure vessel may in particular comprise an inner container which is designed for max. Operating pressures (MOPs) up to about 350 barü (= overpressure relative to the atmospheric pressure), preferably up to about 500 barü, and particularly preferably up to about 700 barü. The outer container preferably closes off the pressure vessel to the outside. Preferably, the cryogenic pressure vessel comprises a vacuum with an absolute pressure in the range of 10 mbar to 10 ^-1 mbar, more preferably from 10 ^-7 mbar to 10 ^-3 mbar and particularly preferably from about 10 ^-5 mbar that at least partially between the inner container and the outer container in an evacuated (intermediate) space or vacuum V is arranged. Storage at temperatures (just) above the critical point has the advantage over storage at temperatures below the critical point that the storage medium is present in a single phase. For example, there is an interface between liquid and gaseous.

The inner container has a plastic material layer. Preferably, the plastic material layer is formed on a liner of the inner container. Between the plastic material layer and the evacuated space V, a barrier layer is at least partially arranged. The barrier layer is designed and arranged in such a way that the barrier layer at least reduces, preferably even completely prevents, the passage of constituents escaping from the plastic material layer into the evacuated space V. The barrier layer is at least partially surrounded by a cover layer.

Plastics tend to leach out under vacuum. Any inclusions that are present in the plastic penetrate slowly into the vacuum. The penetrating into the vacuum components of the plastic material layer, for. B. gas inclusions that have been included during the production of the plastic material layer, reduce the insulating properties of the evacuated space V. Also local residues of incompletely reacted starting materials (including resin and hardener) or auxiliaries, which have an unfavorable vapor pressure curve, have a negative effect on the vacuum out. In particular, plasticizers present in the matrix material of fiber composites, water present or hydrocarbons tend to outgas. Thus, so deteriorate due to this outgassing over time, the thermal properties of the cryogenic pressure vessel. The barrier layer disclosed herein may at least reduce vacuum degradation.

The plastic material layer may be formed as a fiber-reinforced plastic layer laminate. Preferably surrounds the fiber reinforced Plastic layer laminate the liner. As a liner, for example, an aluminum or steel liner can be used. Further preferably, the liner itself can be made of a fiber-reinforced plastic layer laminate or the fiber-reinforced plastic layer laminate itself comprises the liner (including a linerless pressure vessel). In the interior I of the liner, the fuel can be stored cryogenic. Such a fiber-reinforced plastic laminate layer considerably increases the strength of the inner container.

Fiber-reinforced plastics (FRP), for example carbon fiber-reinforced plastics (CFRP) and glass-fiber reinforced plastics (FRP), are used as fiber-reinforced plastic layer laminate or sheathing or reinforcement (hereinafter the term "plastic layer laminate" is used in most cases). The FRP structure of a pressure vessel reinforces by reinforcing fibers embedded in a plastic matrix. An FRP comprises reinforcing fibers and matrix material, which can be combined in a load-oriented manner to give the desired mechanical and chemical properties. The fiber reinforced layer is i. d. R. a layer having the cross and peripheral layers. In order to compensate for axial stresses, cross layers are wound or braided over the entire winding core surface. In the cylindrical shell area are i. d. R. the so-called peripheral layers that provide a reinforcement in the tangential direction. The circumferential positions extend in the circumferential direction U of the pressure vessel and are oriented at a 90 ° angle to the pressure vessel longitudinal axis A-A.

According to the technology disclosed herein, it is proposed to provide a barrier layer between the plastic material layer and the evacuated space V. Thus, only comparatively small amounts or no constituents of the plastic material layer penetrate into the evacuated space V, as a result of which the container insulation can be markedly improved or remains more stable over time. The barrier layer can separate the fiber-reinforced plastic layer laminate substantially gas-tight from the cover layer and / or from the evacuated space V. In particular, during the production of a fiber-reinforced plastic layer laminate, for example by winding and / or braiding, it may occur more frequently to gas inclusions, which can not be completely removed. These gas inclusions would not adversely affect the long-term insulating nature of the pressure vessel in the technology disclosed herein. At the same time, due to the comparatively high inner container pressures associated with the low temperatures, a relatively large amount of fuel can be stored in the inner container. The barrier layer itself preferably has an outgassing-free material at least toward the cover layer and / or to the evacuated space V. This limitation is expediently produced from a gas-free material, so that a deterioration of the insulation by barrier outgassing is avoided. The barrier layer may be made of a metal, in particular of aluminum, steel and / or copper and their alloys. The barrier layer can be made of a fuel-barrier plastic, for. For example, be prepared ethylene-vinyl alcohol copolymer (EVOH). Advantageously, the barrier layer may be formed as a surface coating on the plastic material layer or on a carrier material. The barrier layer may, for example, have the same thermal expansion coefficient as the plastic material layer. The barrier layer may be formed as a film.

The cover layer may be formed to fix the barrier layer at least in regions to the plastic material layer. In other words, the cover layer can mechanically hold the barrier layer in position. Pressure vessels are usually attached by a fixed bearing floating bearing assembly to a body. If the pressure vessel expands due to temperature and / or internal pressure changes, length changes occur in the direction of the pressure vessel longitudinal axis A-A. If the barrier layer is formed as a thin film which does not rest against the plastic layer laminate, changes in length in some regions of the inner container can not be transferred directly to their origin in the barrier layer. However, this can then lead to larger changes in length of the inner container being transferred to the barrier layer in other areas. These larger length expansions can then lead to voltage spikes that can cause damage to the barrier layer. The barrier layer according to the technology disclosed herein can be at least partially fixed to the plastic material layer, the length expansions in the pressure vessel longitudinal direction A-A and / or in the radial direction of the plastic material layer are transferred to the barrier layer. Thus, the elongation of the inner container is uniformly transmitted to the barrier layer. The risk of cracking can thus be reduced.

The cover layer may be configured to release no gases or less gases than the plastic material layer into the vacuum. Preferably, the barrier layer is also formed to carry forces and moments resulting from the inner container. Advantageously, the cover layer may have a modulus of elasticity in the circumferential direction which deviates less than 20%, preferably less than 10% or 5% from the modulus of elasticity of the plastic material layer. Thus, advantageously, a uniform stress of the barrier layer and Plastic layer can be adjusted. Suitably, the cover layer in at least one direction X, Y, Z have a coefficient of thermal expansion, which deviates less than 20%, preferably less than 10% or 5% of the coefficient of thermal expansion of the plastic material layer in the same direction X, Y, Z. Thus, stresses in the component can be further reduced or avoided. Preferably, the plastic material layer is at least a factor of 3, at least by a factor of 5, at least by a factor of 8 or at least by a factor of 10 thicker than the cover layer.

The cover layer may be formed as a fiber-reinforced cover layer laminate. The cover layer laminate can be constructed like the plastic layer laminate. In particular, the cover layer laminate may have a higher fiber content than the plastic layer laminate. If this is the case, the outer layer laminate comprises less matrix material which may tend to outgas. The cover layer laminate can have at least one layer, which is formed exclusively of reinforcing fibers without matrix material, at least in the jacket region of the pressure vessel. Preferably, all layers of the barrier layer are formed without matrix material. For example, the cover layer may be made of a different material than the plastic material layer. For example, the cover layer may be formed of at least 50%, further preferably at least 80% or 90% carbon fiber and / or glass fiber only, which are not provided with matrix material (= dry fibers). For example, other reinforcing fibers may also be provided. By virtue of the fact that the barrier layer can be arranged within the pressure-bearing layer structure, the mechanical requirements for the barrier layer can be lower. Thus, the plastic layer laminate and the cover laminate preferably form the FRP structure which bears the pressure vessel load.

Between the plastic material layer and the barrier layer and / or in the barrier layer itself, a transport layer can be arranged at least in regions. The transport layer may conveniently be fluidly connected to a drain line. The drain line connects the transport layer to the exterior of the cryogenic pressure vessel. Diffuses fuel, eg. As hydrogen, through the liner and / or it comes to outgassing in the plastic material layer, so these gases can accumulate in the transport layer. The barrier prevents these gases from diffusing outward in the radial direction to the evacuated space V. Thus, the gas pressure of the accumulated gas in the transport layer gradually increases, and the gas further spreads within the transport layer. The transport layer is in particular designed to be permeable to gas so that the gases emerging from the plastic layer can reach the discharge line. Alternatively or additionally, a negative pressure which at least partially sucks out these gases may be present on the discharge line. The transport layer can form, for example, microchannels or microcolumns, so that the outgassed components can be discharged to the outside. Further, a valve may be provided on the drain line. The barrier layer may be configured to insulate radiations. Advantageously, thus additional radiation shields can be omitted.

• – Bereitstellen eines fasergewickelten und/oder geflochtenen Kunststoffschichtlaminats, insbesondere des hier offenbarten Kunststoffschichtlaminats;
• – Zumindest bereichsweises Erwärmen des Kunststoffschichtlaminats für eine gewisse Zeit, so dass zumindest 30% der in das Kunststoffschichtlaminat eingeschlossenen Gase aus dem Kunststoffschichtlaminat entweichen bzw. Über der Zeit entwichen sind; und bevorzugt
• – Zumindest bereichsweises Aufbringen einer Deckschicht auf das Kunststoffschichtlaminat, insbesondere der hier offenbarten Deckschicht.

The technology disclosed herein also relates to a method of manufacturing a cryogenic pressure vessel for fuel. In particular, a manufacturing method for the cryogenic pressure vessel disclosed herein. The method comprises the steps:

• - Providing a fiber-wound and / or braided plastic layer laminate, in particular of the plastic layer laminate disclosed herein;
• - At least partially heating the plastic layer laminate for a certain time, so that at least 30% of the gases enclosed in the plastic layer laminate escape from the plastic layer laminate or have escaped over time; and preferred
• - At least partially applying a cover layer on the plastic layer laminate, in particular the cover layer disclosed here.

The plastic layer laminate can, for example, be heated so long and strongly until at least 30%, preferably at least 50%, 70%, 80% or 90% of the gases have escaped from the plastic layer laminate. Thus, the outgassing decreases after the completion of the pressure vessel and the risk of vacuum degradation can be reduced. Further, the method disclosed herein may include the step of applying the topcoat disclosed herein to the barrier layer disclosed herein, particularly by winding and / or braiding reinforcing fibers. Further, the method disclosed herein may also include features disclosed herein in connection with the structural features of the pressure vessel.

The technology disclosed herein will now be described in more detail with reference to the figures, in which:

1 a schematic cross-sectional view of a cryogenic pressure vessel 40 , and

1a an enlarged view of detail A of the 1 shows.

In the 1 is a cryogenic pressure vessel 40 shown here over two suspensions 50 is fixed to the vehicle body (not shown). The pressure vessel 40 includes an inner container 10 and an outer container 30 , The inner container 10 is inside the outer container 30 arranged. Between the inner container 10 and the outer container 30 an evacuated space V is arranged. The inner container 10 is at both ends with the outer container 30 connected.

1a shows enlarged the structure of the inner container 10 , The barrier layer 16 is between the plastic layer laminate 14 and the topcoat 18 arranged. The barrier layer 16 surrounds here the fiber-reinforced plastic layer laminate 14 complete and sealing. It can also be provided that only a part, for example, the cylinder area of the liner 12 , with the plastic layer laminate 14 is surrounded. Then it would be enough, if only this area of the barrier layer 16 is surrounded. The plastic layer laminate 14 surrounds the liner 12 who is here as an aluminum liner 12 is trained. For example, the laminate layer 14 and the topcoat 18 be applied in the winding process. The barrier layer 16 Prevents any inclusions or locally present components with unfavorable vapor pressure curve, which in the plastic layer laminate 14 are present, enter the evacuated room V. Thus, a cryogenic pressure vessel 40 be realized with a comparatively high fluid storage volume and comparatively good long-term heat insulation. Between the plastic layer laminate 14 and the barrier layer 16 here is a transport layer 17 arranged. Any gas, for example fuel gas or previously in the plastic layer laminate 14 embedded gas that enters the transport layer 17 can penetrate within this layer 17 be transported further. The transport layer 17 is fluidly connected to a drain line 19 (see. 1 ). The drainage line 19 is at one end of the inner container 10 intended. Through the drainage pipe 19 can be in the transport layer 17 accumulated gases expediently escape from the pressure vessel. For example, the gases could be sucked or drained. Between the cover layer 18 and the liner 12 creates a press association. The gases emerging from the plastic thereby increase the pressure within the layer structure, but the pressure through the transport layer 17 can be reduced. If there are changes in the length of the inner container 10 comes, the press federation ensures that the local elongation of the inner container 10 in each area or in almost every area of the barrier 16 is transmitted. Thus, the barrier layer also expands 16 evenly. The cover layer 18 In particular, it can also protect the other layers from mechanical influences.

The foregoing description of the present invention is for illustrative purposes only, and not for the purpose of limiting the invention. Various changes and modifications are possible within the scope of the invention without departing from the scope of the invention and its equivalents.

LIST OF REFERENCE NUMBERS

10

inner container

14

Plastic material layer

16

junction

17

transport layer

18

Cover layer, cover layer laminate

19

drain line

30

outer container

40

pressure vessel

V

evacuated room

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1546601 B1 [0003]
• DE 102015213563 A1 [0003]

Claims (11)

Cryogenic pressure vessel ( 40 ) for a motor vehicle, with an inner container ( 10 ) and an outer container ( 30 ), wherein between the inner container ( 10 ) and the outer container ( 30 ) is at least partially an evacuated space (V) is arranged, wherein the inner container ( 10 ) a plastic material layer ( 14 ), wherein between the plastic material layer ( 14 ) and the evacuated space (V) at least partially a barrier layer ( 16 ), wherein the barrier layer ( 16 ) is arranged and arranged such that it makes the transition from the plastic material layer ( 14 ) escape components into the evacuated space (V) at least reduced, wherein the barrier layer ( 16 ) at least partially from a cover layer ( 18 ) is surrounded. Pressure vessel ( 40 ) according to claim 1, wherein the cover layer ( 18 ) is formed, the barrier layer ( 16 ) at least partially to the plastic material layer ( 14 ) to fix. A pressure vessel according to claim 1 or 2, wherein the cover layer ( 18 ) a fiber-reinforced cover laminate ( 18 ), and / or wherein the plastic material layer ( 14 ) a fiber-reinforced plastic layer laminate ( 14 ). Pressure vessel ( 40 ) according to claim 3, wherein the cover layer laminate ( 18 ) has a higher fiber content than the plastic layer laminate ( 14 ). Pressure vessel ( 40 ) according to claim 3 or 4, wherein the cover layer laminate ( 18 ) at least in the jacket region of the pressure vessel ( 40 ) has at least one layer which is formed exclusively of reinforcing fibers without matrix material. Pressure vessel ( 40 ) according to one of the preceding claims, wherein the barrier layer ( 16 ) the plastic material layer ( 14 ) substantially gas-tight from the cover layer ( 18 ) and / or separated from the evacuated space (V). Pressure vessel ( 40 ) according to one of the preceding claims, wherein the barrier layer ( 16 ) is made of a metal and / or a fuel-barrier plastic. Pressure vessel ( 40 ) according to one of the preceding claims, wherein between the plastic material layer ( 14 ) and the barrier layer ( 16 ) and / or in the barrier layer ( 16 ) at least partially a transport layer ( 17 ), the transport layer ( 17 ) with a discharge channel ( 19 ) is fluidly connected Pressure vessel ( 40 ) according to one of the preceding claims, wherein the barrier layer ( 16 ) is designed to isolate radiations. Method for producing a cryogenic pressure vessel ( 40 ) for fuel, comprising the steps of: - providing a fiber-wound and / or braided plastic layer laminate ( 14 ); At least partially heating the plastic layer laminate ( 14 ), so that at least 30% of the enclosed gases from the plastic layer laminate ( 14 ) escape; and - at least partially applying a barrier layer ( 16 ) on the plastic layer laminate ( 14 ). The method of claim 10, further comprising the step of: - applying a cover layer ( 18 ) on the barrier layer ( 16 ), in particular by winding and / or braiding of reinforcing fibers.

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