DE102010000966B4 - Pressure accumulators, in particular hydrogen pressure accumulators - Google Patents

Abstract

Pressure accumulator (1) with a container body (10) for absorbing pressure forces which are formed by pressure filling of a fluid that can be filled in the storage space (11) of the container body (10), characterized in that the container body (10) is enclosed by an enveloping body (12) is, wherein between the container body (10) and the enveloping body (12) an intermediate space (13) is formed in which the fluid is received under a pressure which is less than the fluid pressure in the storage space (11) and which is greater than a Atmospheric pressure, the intermediate space (13) being filled with a deformation energy absorbing filler, preferably with a metal foam.

Description

The present invention relates to a pressure accumulator with a container body for absorbing compressive forces which are formed by pressure filling of a fluid that can be filled in the storage space of the container body.

State of the art

Pressure accumulators for hydrogen, for example, which are installed in a vehicle, for example, are known from the prior art. Known pressure accumulators have a container body which is under high pressure, for example by filling with hydrogen up to 700 bar. The hydrogen can be filled into and withdrawn from the storage space via a valve.

Various types are known for the construction of the wall of the container body, earlier types I and II using steel as the tank wall material, which is very heavy and therefore disadvantageous for pressure accumulators that are installed in vehicles, for example. Newer types III and IV use an internal aluminum liner or a polymer liner to form the container body, which is surrounded by a carbon fiber-reinforced polymer. The task of the aluminum liner is to minimize the permeation of hydrogen through the walls of the container body. A pressure accumulator according to type IV has a container body made of a carbon fiber reinforced polymer, which means that increased permeation of hydrogen compared to the pressure accumulator type III has to be accepted, but carbon fiber-based pressure tanks offer a favorable weight in relation to the achievable tank volume.

Between a full pressure filling of the storage space in the container body, for example with hydrogen up to 700 bar, and a complete emptying up to only 5 bar, the container body can have an expansion of up to 2% of the volume. As a result, the diameter and length of a pressure accumulator in a cylindrical shape increases or decreases in the order of cm. This effect is called the "breathing" of the pressure accumulator. In the case of type III pressure accumulators, alternating loads can easily lead to increased leaks. Consequently, high demands are also placed on a polymer shell with regard to high mechanical stability and low hydrogen permeability.

From the DE 10 2008 039 573 A1 a pressure accumulator with a container body for absorbing compressive forces is known, which is constructed in several layers and has at least one inner shell and one outer shell. The respective shells of the pressure accumulator build on each other mechanically, a filament winding process being proposed for the outer shell in order to absorb the high pressure forces caused by the pressure filling in the storage space. In contrast, the inner shell is used to create the tightness, so that it is proposed to produce the inner shell from a polyethylene, a PET, an ethylene vinyl alcohol or an ethylene-vinyl acetate terpolymer. Consequently, the pressure accumulator shown corresponds to type IV, the liner being formed by a plastic material.

From the DE 101 60 701 A1 a tank for pressurized liquids and / or gases is also known which has a plurality of containers. At least two of these containers are nested within one another.

From the U.S. 3,282,459 A is known a tank for high pressure, high temperature fluids.

From the U.S. 4,805,445 A a storage unit with multiple casings is known.

From US 2008/0168776 A1 a compressed gas reservoir with a casing is known.

In such pressure accumulators known from the prior art, there is the disadvantage that, on the one hand, a high permeability has to be accepted, which leads to a loss of the fluid in the storage space. Furthermore, even with multi-layer container bodies there is the disadvantage that in the event of a crash, for example in the event of a mechanical external effect on the container wall, a leak can occur or, in the worst case, even a sudden pressure loss can result. It is therefore desirable to further increase the safety of pressure accumulators, in particular of hydrogen accumulators, the aim being at the same time to minimize the permeability and thus the pressure loss of the hydrogen.

Disclosure of the invention

It is therefore the object of the present invention to achieve a pressure accumulator of the type described above with increased safety in the event of external mechanical action and with simultaneously reduced permeability in order to minimize the loss of fluids received in the container body.

This object is achieved on the basis of a pressure accumulator according to the preamble of claim 1 in conjunction with the characterizing features. Advantageous further developments of the inventions are given in the dependent claims.

The invention includes the technical teaching that the container body is enclosed by an enveloping body, an intermediate space being formed between the container body and the enveloping body, in which the fluid is received under a pressure that is less than and greater than the fluid pressure in the storage space is than an atmospheric pressure.

The design of a pressure accumulator according to the invention has the advantage that by constructing the pressure accumulator with a container body and an enveloping body with an intermediate space provided between the container body and the enveloping body, both the security of the pressure accumulator can be increased and the permeability can be minimized. In the event of a crash, for example due to an accident in a vehicle in which the pressure accumulator is installed, a mechanical effect acts mainly or exclusively on the enveloping body, and an effect on the container body can only take place through massive deformation of the enveloping body. The intermediate space according to the invention between the container body and the enveloping body consequently minimizes or even excludes the mechanical effect on the container body. The permeation is also minimized, since this is a function of the pressure difference between the inside and the outside of a wall. Since there is a very low fluid pressure in the intermediate space, there is only minimal or no diffusion of the enclosed fluid to the outside of the enveloping body, on which atmospheric pressure prevails. The intermediate space consequently acts as a type of pressure buffer, wherein the fluid diffusing through the container body and entering the intermediate space can also be used, as described in more detail below.

Furthermore, according to the invention, the intermediate space is filled with a filler which enables energy to be absorbed in the event of deformation, wherein the filler can preferably be formed by a metal foam. When selecting the filler, it is important to be able to absorb energy in the event of a crash, in order to minimize any effect on the container body, which absorbs the pressure forces caused by the pressure filling of the pressurized fluid in the storage space. Thus, the intermediate space can either form a cavity or this is at least partially filled with the filler, wherein the filler can in turn serve to increase the structural rigidity of the pressure accumulator.

The pressure accumulator according to the invention can advantageously be used for a fluid which consists of hydrogen, so that the pressure accumulator is designed as a hydrogen pressure accumulator. Due to the diatomic structure and the small size of the H ₂ Atoms have a very high tendency to diffuse, so that a pressure accumulator designed according to the invention is particularly suitable for storing hydrogen.

The pressure accumulator can be designed with particular advantage for installation in a motor vehicle. Installation in motor vehicles that are operated with hydrogen as the energy carrier, such as, for example, with a hydrogen internal combustion engine or with a fuel cell drive, is particularly advantageous. The hydrogen pressure accumulator according to the invention can advantageously be used here.

According to a further advantageous embodiment, the container body can be formed from a plastic liner or an aluminum liner around which a winding of a fiber material is wrapped. Due to the geometric separation of the container body with the enveloping body, the movement through the "breathing" of the container body through pressure filling and emptying of the storage space takes place only in the container body. The breathing movement is essentially not transmitted to the enveloping body, which results in advantages in the arrangement of the pressure accumulator, in particular when the pressure accumulator is fastened in a motor vehicle.

The container body can in principle be formed from a plastic liner or an aluminum liner, the liner being wrapped with a winding of a fiber material. The liner initially forms the basic shape of the container body, the compressive forces being absorbed by the winding of the fiber material. Consequently, the container body can form a pressure accumulator which is designed in the manner of a type III or type IV pressure accumulator. In addition to this prior art, the enveloping body is created with a spacing for the formation of the intermediate space around the container body in order to overcome the disadvantages of the prior art on which the invention is based.

Alternatively, the container body itself can be made from a fiber-reinforced polymer, materials being known which, as fiber composites, can cure by a thermal process in such a way that a dimensionally stable container body is created, the fiber portion in the composite being used to absorb compressive forces.

According to a further possible embodiment of the pressure accumulator according to the invention, a secondary accumulator can be provided which is fluidically connected to the intermediate space via a fluid line. The secondary storage offers a storage space, whereby through the fluidic connection this storage space with the interspace allows an increase in the volume of the interspace. This results in the possibility of increasing the amount of fluid that reaches the intermediate space by diffusion through the container body. The secondary storage can be arranged spatially separated from the pressure storage, wherein the fluid line for connecting the secondary storage with the intermediate space can have the appropriate length. There is also the possibility of arranging the secondary storage device adjacent to the pressure storage device, so that the secondary storage device at least partially encloses the pressure storage device, for example. The secondary storage device can, for example, have a rectangular shape or any cuboid or free form, the pressure storage device preferably having a cylindrical shape with rounded ends, since a round cross section of the pressure storage device can better absorb high pressure forces due to the pressure filling of the storage space with the fluid. In contrast, the secondary storage unit takes up the fluid only at a low pressure, for example a maximum of 3 bar, so that the secondary storage unit can advantageously have any shape and can preferably enclose the container body. This results in an improved utilization of space when installing the pressure accumulator, for example in a motor vehicle.

It is also advantageous that the secondary storage unit is filled with a low-temperature metal hydride. Likewise, the space can be filled with a low-temperature metal hydride. Metal hydrides are particularly suitable for storing hydrogen without putting it under high pressure. For example, a metal hydride unit can store up to 600 units of gaseous hydrogen. A combination of filler to absorb deformation energy and of metal hydride to store hydrogen offers a further advantageous embodiment for filling up the space.

The storage space can be fluidically connected to a consumer via at least one valve. Furthermore, the intermediate space and / or the secondary storage unit can also be connected to a consumer, for which purpose a further valve can be used. For example, when a limit pressure is reached in the intermediate space or in the secondary storage unit, a valve can open in order to supply the fluid to the consumer. The fluid lost through permeation from the storage space of the container body can thus also be fed to a consumer, preferably the same consumer.

Figure list

• 1 eine schematische Ansicht eines Ausführungsbeispieles eines Druckspeichers und
• 2 eine schematische Darstellung eines weiteren Ausführungsbeispieles des erfindungsgemäßen Druckspeichers mit einem Nebenspeicher.

Further measures improving the invention are shown in more detail below together with the description of preferred exemplary embodiments of the invention with reference to the figures. It shows:

• 1 a schematic view of an embodiment of a pressure accumulator and
• 2 a schematic representation of a further embodiment of the pressure accumulator according to the invention with a secondary storage.

The in 1 illustrated pressure accumulator 1 forms one possible embodiment of the present invention. The pressure accumulator 1 has a container body 10 to absorb compressive forces caused by pressure filling a in the storage space 11 of the container body 10 fillable fluids are formed. The container body 10 can have an aluminum or a plastic liner, which is wrapped with a fiber material for reinforcement. This allows the container body 10 a pressure accumulator according to type III or type IV correspond to the design described above. In the storage room 11 is hydrogen stored, what with the chemical indication H ₂ is marked.

According to the invention is the container body 10 with an enveloping body 12th enclosed, with between the container body 10 and the enveloping body 12th a gap 13th is formed in which the fluid is received under a pressure which is less than the fluid pressure in the storage space 11 and which is greater than atmospheric pressure. The storage room 11 can be filled with hydrogen of up to 700 bar, whereby the pressure in the gap 13th can be limited to, for example, 3 bar. The enveloping body 12th can for example be made of a light metal or a polymer, with a pressure fluctuation from 0 to, for example, 3 bar, no significant geometric change in the enveloping body 12th evokes. However, the container body can 10 expand due to the breathing movement described in the introduction, so that the space 13th gets bigger and smaller. The compressive forces that cause movement in the container body 10 cause are indicated by arrows. The gap 13th can be filled with a deformation energy absorbing filler such as a metal foam. There is also the possibility of the space in between 13th to be filled with a low-temperature metal hydride.

Via a fluid line 17th can the storage space 11 with a valve 16 be connected to the one in the storage space 11 to remove stored hydrogen. Via another fluid line 20th is the space in between 13th with a valve 18th connected to the hydrogen that permeates through the container body 10 from storage space 11 in the space 13th gets through the valve 18th also to be supplied to a consumer. This can be done via the valve 16 provided fluid are fed to the same consumer as that via the valve 18th provided fluid.

2 shows a further embodiment of a pressure accumulator according to the invention 1 with a container body 10 , an enveloping body 12th and one between the container body 10 and the enveloping body 12th formed space 13th . In this exemplary embodiment, there is a secondary memory 14th provided via a fluid line 15th with the space in between 13th connected is. The secondary storage 14th is spatially separated from the pressure accumulator 1 shown, but this is part of the pressure accumulator in the context of the present invention 1 . The secondary storage 14th provides an expansion of the storage volume, which is through the gap 13th is formed. In the secondary storage 14th is exemplary a low-temperature metal hydride 19th indicated in order to enable a volume-efficient storage of hydrogen. Due to a high pressure in the storage space 11 that can handle hydrogen up to 700 bar H ₂ can store, a diffusion of the hydrogen takes place through the wall of the container body 10 in the space 13th . The one in the space 13th Diffusing hydrogen can pass through the fluid line 15th in the secondary storage 14th get through the low temperature metal hydride 19th be included. A fluid line is also an example 21 shown, which is the fluid line 15th with a valve 18th connects, via which hydrogen can be made available to a consumer. The consumer can be the same consumer that supplies hydrogen via the fluid line 17th and the valve 16 which is supplied in the storage space 11 is stored. The valve 16 can be equipped with a pressure reducer, which reduces the provided hydrogen from the filling pressure in the storage space 11 reduced to a consumer pressure.

The present invention is not limited in its implementation to the preferred exemplary embodiments specified above. Rather, a number of variants are conceivable which make use of the solution shown even in the case of fundamentally different designs. All of the features and / or advantages arising from the claims, the description or the drawings, including structural details, spatial arrangements and method steps, can be essential to the invention both individually and in a wide variety of combinations.

Claims (10)

Pressure accumulator (1) with a container body (10) for absorbing pressure forces which are formed by pressure filling of a fluid that can be filled in the storage space (11) of the container body (10), characterized in that the container body (10) is enclosed by an enveloping body (12) is, wherein between the container body (10) and the enveloping body (12) an intermediate space (13) is formed in which the fluid is received under a pressure which is less than the fluid pressure in the storage space (11) and which is greater than a Atmospheric pressure, the intermediate space (13) being filled with a deformation energy absorbing filler, preferably with a metal foam. Pressure accumulator (1) Claim 1 , characterized in that the fluid is hydrogen and that the pressure accumulator (1) is designed as a hydrogen pressure accumulator (1). Pressure accumulator (1) Claim 1 or 2 , characterized in that the pressure accumulator (1) is designed for installation in a motor vehicle. Pressure accumulator (1) after one of the Claims 1 until 3 , characterized in that the container body (10) is formed from a plastic liner or an aluminum liner around which a winding of a fiber material is wrapped. Pressure accumulator (1) according to one of the preceding claims, characterized in that the container body (10) is formed from a fiber-reinforced polymer. Pressure accumulator (1) according to one of the preceding claims, characterized in that a secondary accumulator (14) is provided which is fluidically connected to the intermediate space (13) via a fluid line (15). Pressure accumulator (1) Claim 6 , characterized in that the secondary storage (14) is filled with a low-temperature metal hydride (19). Pressure accumulator (1) according to one of the preceding claims, characterized in that the intermediate space (13) is filled with a low-temperature metal hydride. Pressure accumulator (1) according to one of the preceding claims, characterized in that the storage space (11) is fluidically connected to a consumer via at least one valve (16). Pressure accumulator (1) according to one of the preceding claims, characterized in that the intermediate space (13) or the secondary accumulator (14) is fluidically connected to a consumer.

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