Patent Application
20180259125
The invention which is disclosed herein relates to a pressure vessel including a load ring, to a motor vehicle including a pressure vessel, and to a method for producing a pressure vessel.
Pressure vessels expand in a manner which is dependent on factors such as the interior pressure p or the temperature T of the pressure vessel. For this reason, pressure vessels are attached to the vehicle body of a motor vehicle in accordance with the locating bearing/floating bearing principle. A construction of this type requires a relatively large amount of installation space. Moreover, it is not capable of transmitting forces and torques from one end of a pressure vessel to another end of the pressure vessel. Said pressure vessels therefore do not contribute or contribute only to a small extent to the rigidity of the vehicle body.
DE 1993551 6 A1 has disclosed a cylinder for pressurized gases having a holding ring flange at the respective ends of the cylinder. Furthermore, DE 10 2010 053874 A1 discloses a holding system for a pressure vessel having two securing caps.
It is an object of the invention which is disclosed herein to reduce or to eliminate the disadvantages of the previously known solutions. In particular, it is an object of the invention which is disclosed herein to provide easier and more compact ways for vehicle integration of a pressure vessel. It is possible, in particular, for this to be a load-bearing pressure vessel. Further objects result from the advantageous effects of the invention which is disclosed herein.
This and other objects are achieved by way of a pressure vessel for storing fuel, a motor vehicle including such a pressure vessel, and/or a method for producing a pressure vessel in accordance with embodiments of the present invention.
The invention which is disclosed herein relates to a pressure vessel for storing fuel for a motor vehicle. A pressure vessel of this type can be, for example, a cryogenic pressure vessel or a high pressure gas vessel.
High pressure gas vessels are configured to store fuel (for example, hydrogen) substantially at ambient temperatures over the long term at a maximum operating pressure (also called MOP) of over approximately 350 bar(g), further preferably of over approximately 500 bar(g) and particularly preferably of over approximately 700 bar(g). High pressure gas vessels are defined, for example, in the standard EN13445. Type III and type IV pressure vessels have, for example, an inner liner made from aluminum and from plastic, respectively, and a fiber-reinforced layer or encapsulation made from fiber-reinforced plastic (FRP). What is known as a type V high pressure gas vessel can advantageously also be provided, that is to say a liner-less pressure vessel.
A cryogenic pressure vessel can store fuel in the liquid or supercritical physical state. A thermodynamic state of a substance, which thermodynamic state is at a higher temperature and at a higher pressure than the critical point, is called a supercritical physical state. A cryogenic pressure vessel is suitable, in particular, to store the fuel at temperatures which lie considerably below the operating temperature (that temperature range of the vehicle environment is meant, 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 from approximately −40° C. to approximately +85° C.). The fuel can be, for example, hydrogen which is stored in the cryogenic pressure vessel at temperatures of approximately from 34 K to 360 K.
In order to obtain a pressure vessel with a stress distribution which is as favorable as possible and with regard to the vehicle integration, an elongate pressure vessel with curved (preferably semi-elliptical) pole caps at the two lateral ends (also called domes) is favorable. A pressure vessel of this type can be integrated, for example, centrally in the vehicle tunnel.
The pressure vessel which is disclosed herein for storing fuel in a motor vehicle includes a liner and a fiber-reinforced layer which surrounds the liner at least in regions. Fiber-reinforced plastics (FRP) are used as a fiber-reinforced layer or encapsulation or reinforcement (in the following text, the term “fiber-reinforced layer” is mostly used), for example carbon fiber reinforced plastics (CFRP) and glass fiber reinforced plastics (GFRP). The FRP structure of a pressure vessel has a reinforcing effect as a result of fibers which are embedded in a plastic matrix. An FRP includes fibers and matrix material which have to be combined in a load-oriented manner, in order that the desired mechanical and chemical properties result. The fiber-reinforced layer is usually a layer which has cross-laid plies and circumferential plies. Normally, they handle the entire stresses which result from the interior pressure. In order to compensate for axial stresses, cross-laid plies are wound or woven over the entire liner area. What are known as the circumferential plies which ensure reinforcement in the tangential direction are situated in the cylindrical shell region M. The circumferential plies run in the circumferential direction U of the pressure vessel. The circumferential plies are oriented at a 90° angle with respect to the pressure vessel longitudinal axis A-A.
The technology which is disclosed herein likewise relates to a liner for a pressure vessel for storing fuel. The liner can be produced from a metal, from a metal alloy or from a plastic. For example, a liner made from aluminum or an aluminum alloy is expedient. The fuel is stored in the liner, and the liner is usually responsible for the tightness of the pressure vessel. If, for example, hydrogen is stored, the liner is usually configured to avoid hydrogen permeation. In addition, the liner usually serves as a wound and/or woven core. A metallic embodiment can be designed both in a load-bearing manner and, like a polymer liner, in a non-load-bearing manner. The liner contour is usually selected to be as thin as possible, since the strength of the fiber composite is substantially higher and therefore a thinner overall wall thickness can be achieved. For example, the maximum wall thickness of the liner can be less than 30 mm, preferably less than 10 mm or 5 mm. Just like the pressure vessel, the liner also usually has an elongate shape with curved pole caps. The pole caps and the cylindrical shell region M which is arranged in between are, in particular, advantageously shaped in one piece. An opening is provided in at least one of the pole caps of the liner.
A stub (also called a boss or port) is provided at the opening of the liner. Pressure vessels including a plastic liner usually have a metallic boss. The pressure vessels with a metallic liner normally do not have an additional boss. They have what are known as ports. The boss is usually produced from a steel alloy or aluminum alloy. The boss is advantageously covered at least partially by the fiber-reinforced layer. The boss can serve to connect any fuel lines to the pressure vessel. The boss can have, for example, a neck, to which a fuel line can be flange-connected. To this end, further components can be inserted into the boss, for example by way of an internal thread. At the end which lies opposite the neck, a connecting section of widening configuration can be provided, which connecting section advantageously has the same contour at least in regions as the pole cap of the liner. Said connecting section preferably lies on the liner.
The technology which is disclosed herein includes, furthermore, at least one load ring or load transmission ring or load introduction ring (hereinafter “load ring”) which surrounds the liner at least in regions. In other words, the load ring encloses the outer surface of the liner at least at one point. Here, a load ring is an annular element which is configured to introduce or to transmit forces and/or torques (=loads) into the pressure vessel. The load ring can be produced from a metal, from a plastic or from a metal alloy.
In particular, the load ring can be arranged in the transition regions from the cylinder to the dome of the pressure vessel. Here, the transition region Ü can be the region, in which the liner already has at least 80%, preferably at least 90%, of the mean diameter D1 which the liner has in the (substantially cylindrical) shell region M. In particular, the transition region can protrude into the shell region M. For example, the transition region Ü can protrude into the shell region M by at most 10% or at most 5% of the entire axial length of the shell region M. The load ring can be arranged immediately laterally adjacently in the axial direction with respect to a circumferential ply region of the fiber-reinforced layer. At least one fiber ply runs in the circumferential direction (hoop ply) in the circumferential ply region of the fiber-reinforced layer. The circumferential ply region is expediently arranged in the shell region M. In particular, the load ring is arranged adjacently with respect to that region of the fiber-reinforced layer, in which the layer thickness of the fiber-reinforced layer is higher on account of the circumferential plies than in the region, in which the load ring is arranged.
The load ring can be configured, for example, as a solid material, for example as an annular plate or clamp. For example, the load ring can have cutouts. The cutouts which are provided in the load ring can advantageously be designed in such a way that a framework structure is produced. Furthermore, it is contemplated that a wire structure (for example, wire mesh) or a lattice structure configures the load ring, from the surface of which the connecting pins or bolts extend away. The framework might also be realized in a different way than by way of stamped-out portions. The framework and/or the wire or lattice structure can be based, for example, on a metallic material and/or on a fiber composite material. Here, the wires, lattices and/or fibers are advantageously oriented in such a way that, in the case of the transmission of forces and/or torques between the connecting pins and the bolts (see below), they act for the most part in accordance with the principle of tension rods or pressure rods. The load ring itself preferably includes at least one laminate layer made from a fiber-reinforced plastic. The fibers of at least one (in particular, unidirectional) ply of the laminate layer are preferably arranged in the circumferential direction (hoop plies). Further plies of the laminate layer can be oriented in a different way. The laminate layer can firstly transmit the forces and/or torques between the connecting pins and bolts, and secondly can also support the fiber-reinforced layer in the pole regions with regard to the forces which result from the vessel interior pressure.
Connecting pins project from the surface of the load ring in a manner which is directed outward. The connecting pins project or protrude out of the fiber-reinforced layer. A load ring can have at least two, preferably at least four connecting pins. In particular, the connecting pins can be configured and arranged in such a way that reinforcing fibers of the fiber-reinforced layer can run between two connecting pins which are adjacent in the circumferential direction. In this way, the load ring and the pole caps can be wound around or woven around simply. Furthermore, the forces and torques which are transmitted by the vehicle body can be introduced into the fiber-reinforced layer in an improved manner. Stress peaks are reduced here. The connecting pins can be fastened to the load ring in an integrally joined manner, for example by way of welding, adhesive bonding, soldering and/or overmolding. The connecting pins and the load ring can further preferably be produced in one piece by way of a primary forming production method. A support reinforcement can be provided at the base of at least one connecting pin (preferably of each load-bearing connecting pin), which support reinforcement can be connected to the load ring in an integrally joined manner. This is preferably a thickened material portion in the region of the connecting pins which configure the transition to the dome cap. The support reinforcements are preferably shaped in such a way that forces which act on the connecting pins can be introduced satisfactorily into the liner and/or into the fiber-reinforced layer. The support reinforcement advantageously widens toward the surface of the load ring. Consequently, the connecting pin therefore has a lower thickness at its free end than at its base which is connected to the load ring. Therefore, stress concentrations in the transition from the connecting pins to the load ring can be reduced. However, the connecting pins particularly preferably do not protrude in the radial direction in relation to the maximum outer circumference of the pressure cylinder. In this way, the required installation space can be restricted further. Furthermore, the risk of undesired and possibly unnoticed damage during the transport of the pressure vessels is reduced.
At least one connecting pin is particularly preferably configured to transmit external loads from a vehicle body of the motor vehicle into the liner and/or into the fiber-reinforced layer of the pressure vessel. To this end, in the installed position of the pressure vessel, at least one part region of at least one connecting pin is preferably coupled directly or indirectly to the vehicle body, with the result that forces can be transmitted. For example, to this end, the connecting pin can have an external thread and/or an internal thread. A fixing mechanism can further preferably be provided for coupling the at least one connecting pin, as disclosed in the German patent application of the applicant with the application number DE 10 2015 206825.0. The disclosures of DE 10 2015 206825.0 which include the fixing mechanism (designations 143, 144; 143′, 144′ therein), its functional arrangement, the interaction with the connecting pin, and the connecting pin itself are herein expressly incorporated by reference. The disclosures of the German patent application of the applicant DE 10 2015 206826.9 which include the fastening apparatus (designations 140, 140′ therein) are likewise herein expressly incorporated by reference.
By way of the invention which is disclosed herein, it is advantageously possible to transmit forces and torques from the vehicle body into the pressure vessel. The overall rigidity of the motor vehicle can therefore be increased significantly in a manner which is inexpensive, approximately weight-neutral and associated with a small installation space requirement.
Furthermore, the technology which is disclosed herein relates to a motor vehicle, in particular a two-track motor vehicle, including a pressure vessel as disclosed herein. The connecting pins of the pressure vessel can advantageously be coupled to vehicle body attaching elements (for example, the abovementioned fixing mechanism) of the motor vehicle in such a way that forces and/or torques can be transmitted from the vehicle body into the pressure vessel. The pressure vessel (in particular, the at least one load ring, the liner and the fiber-reinforced layer) can be configured to transmit forces and/or torques which are greater in terms of the magnitude, for example at least by a factor of 2.5, 4, 8, 10, 20 or 100, than the forces and/or torques which result during operation from the mass of the pressure vessel and the fuel which is contained therein (for example, weight force, transverse acceleration, etc.). In each case one load ring is preferably provided in the two transition regions Ü to the ends of the at least one pressure vessel. In this way, forces can advantageously be introduced at a first end P1 of the pressure vessel from the vehicle body into the pressure vessel, and can be dissipated at the second end P2 of the pressure vessel into the vehicle body again. The pressure vessel can therefore be configured as a load-bearing pressure vessel or as a reinforcing element of the vehicle body. The vehicle body can therefore be reinforced without additional struts.
Furthermore, the load ring can include bolts which likewise project to the outside from the surface of the load ring. The bolts preferably do not protrude out of the fiber-reinforced layer. The bolts can serve, in particular, to introduce the forces into the fiber-reinforced layer, which forces were introduced via the connecting pins in the load ring. The bolts are preferably shorter and/or thinner than the connecting pins. In this way, the weight and material costs of the load ring can advantageously be reduced.
The connecting pins and/or the bolts are preferably arranged in such a way that more reinforcing fibers of the fiber-reinforced layer can be laid on the end/ends in the circumferential direction U than in the case of a configuration without connecting pins and/or bolts. In other words, the connecting pins and/or bolts can be configured and arranged in such a way that they act as winding and/or weaving aids, by reinforcing fibers or rovings being supported laterally and therefore being saved from sliding off even in the case, for example, of being deposited in a non-geodetic manner. The connecting pins and/or the bolts are preferably arranged concentrically or substantially concentrically around the opening of the liner.
The bolts and/or the connecting pins are particularly preferably arranged spaced apart from the opening of the pressure vessel. If the bolts and/or connecting pins are arranged in a manner which is spaced apart, forces and/or torques can be introduced into the pressure vessel in a particularly satisfactory manner. The load ring preferably has an internal diameter which corresponds to approximately from 80% to 120% of the mean external diameter of the liner in the shell region M. The load ring preferably has a ring width of from 5 mm to 200 mm, further preferably of from 10 mm to 100 mm, and particularly preferably of from 15 mm to approximately 50 mm. If the load ring has a certain width, the tilting moments are reduced. If the load ring is too wide, however, the weight is increased and assembly is made more difficult. The load ring itself (without bolts and/or connecting pins) preferably has a thickness of from 0.1 mm to 10 mm, further preferably of from 0.25 mm to 5 mm, and particularly preferably of from 0.5 mm to approximately 2 mm.
The load ring can be arranged, in particular, in a cut-out region of the liner, for example in a groove or in an annular seat. The groove and the load ring can be configured in such a way that the surface of the load ring terminates flush with the surface of the liner. In this way, stress peaks in the fiber-reinforced layer can advantageously be reduced.
In addition to a circular cross-sectional geometry, the connecting pins and/or bolts can also have different cross-sectional geometries (for example, oval or elongate cross-sectional geometries). They are configured and arranged, in particular, in such a way that fibers of the fiber-reinforced layer can run between adjacent bolts and connecting pins.
The load ring can be configured, in particular, in one piece with a boss or port of the pressure vessel.
The load ring can lie directly or indirectly on the liner and/or possibly on the boss or port at least in regions. In this context, “indirect” means that at least one intermediate layer can be arranged between the load ring and the liner and/or possibly boss or port. Said intermediate layer can serve, for example, to prevent contact corrosion between two metal materials. An intermediate layer can also serve to fix the load ring during the weaving and/or winding process. A fiber-reinforced layer might likewise be used as an intermediate layer. The load ring can therefore also be attached to some layers of fiber material of the fiber-reinforced layer. It does not necessarily have to lie on the liner. For example, a pair of plies of the fiber-reinforced layer might first of all be applied, then the load ring might be positioned onto said plies, before subsequently further plies of the fiber-reinforced layer are deposited.
Furthermore, the invention which is disclosed herein also relates to a method for producing a pressure vessel. The method includes the acts of:
The fiber-reinforced layer or encapsulation is usually produced in a winding process and/or in a weaving process. The thickness of the fiber-reinforced layer is preferably lower at least in regions than the length of at least two connecting pins, with the result that, in the installed position of the pressure tank, the connecting pins can be coupled directly or indirectly to the vehicle body.
The invention which is disclosed herein also relates to a component for introducing mechanical loads into the fiber composite material reinforcement of a pressure vessel, in particular in the transition region between the cylinder and the dome. The pressure vessel includes an annular crown (e.g., load ring or ring) with connecting pins which are arranged to the outside parallel to the radius and penetrate the laminate from the inside to the outside over its entire thickness. Mechanical load can be introduced from the outside into the pressure vessel using the connecting pins. The connecting pins are expediently made from solid material, the length of which protrudes beyond the surface of the laminate, possibly with a thread. Therefore, the introduction of tensile, compressive and torsional loads can take place via a positively locking and screwed attachment. In addition to the connecting pins, further shorter and thinner bolts can be attached on the ring in a similar arrangement as the connecting pins for the introduction of force. The further bolts introduce the load into the CFRP reinforcement in a manner which is distributed uniformly over the entire circumference of the ring, and therefore reduce the stress peaks at the load introduction points. Excessively high stress peaks can lead to damage of the material. The load ring can be manufactured from a metallic material, a fiber composite material or another suitable material. The load ring can be designed in such a way that it also absorbs circumferential and flexural stresses which are caused by the interior pressure, and therefore smoothes the characteristic stress peaks in said region. The connecting pins can be designed in a neutral manner in terms of installation space and/or diameter by being positioned next to the end of the circumferential plies of the CFRP reinforcement. In addition, it is contemplated that the load ring is sunk into a groove in the liner, in order to make a step-less transition between the liner and the load ring and a smaller diameter possible.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.
The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2015 222 392.2 | Nov 2015 | DE | national |
This application is a continuation of PCT International Application No. PCT/EP2016/073877, filed Oct. 6, 2016, which claims priority under 35 U.S.C. § 119 from German Patent Application No. 10 2015 222 392.2, filed Nov. 13, 2015, the entire disclosures of which are herein expressly incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2016/073877 | Oct 2016 | US |
| Child | 15977557 | US |
