FIBER-REINFORCED PRESSURE VESSEL

Abstract

A pressure vessel is disclosed comprising an inner vessel with a rotationally symmetrical middle part with an axis of symmetry along the middle part and two dome-shaped polar caps which close off the middle part, and an outer layer, wound on the inner vessel to reinforce it, made of fiber composite material made of a plurality of plies of fibers embedded in a matrix material which are arranged one above another, which run as a fiber band made of a number of fibers with a location-dependent and position-dependent fiber orientation across the inner vessel, wherein the fiber band at least in some of the plies enters from the middle part at a respective entry fiber angle relative to the axis of symmetry into the region of the dome-shaped polar caps.

Claims

1. A fiber-reinforced pressure vessel comprising an inner vessel with a rotationally symmetrical middle part, preferably a cylindrical middle part, with an axis of symmetry, preferably a cylinder axis, along the middle part and two dome-shaped polar caps which close off the middle part, and an outer layer, wound on the inner vessel to reinforce it, made of fiber composite material made of a plurality of plies of fibers embedded in a matrix material which are arranged one above another, which run as a fiber band made of a number of fibers with a location-dependent and position-dependent fiber orientation across the inner vessel, wherein the fiber band at least in some of the plies enters from the middle part at a respective entry fiber angle relative to the axis of symmetry into the region of the dome-shaped polar caps and is guided there at a respective point of reversal in its winding direction back in the direction of the middle part, and has at least one twist in the region of the polar caps.

2. The pressure vessel according to claim 1, characterized in that the outer layer is wound with steep and flat helical plies.

3. The pressure vessel according to claim 1, characterized in that all the fiber bands have at least one twist in the region of the polar caps.

4. The pressure vessel according to claim 1, characterized in that the twist is a twist through precisely 180 degrees.

5. The pressure vessel according to claim 1, characterized in that the twist is arranged at the point of reversal of the respective fiber band.

6. The pressure vessel according to claim 1, characterized in that the fiber band has a width of between 5% and 15%, preferably between 9% and 11%, of the diameter of the middle part.

7. The pressure vessel according claim 1, characterized in that the at least one twist of the respective fiber bands as a ply with the same entry fiber angle is/are arranged as an arrangement of twists on a circle about a geometric midpoint of the polar cap, with a diameter of the circle depending inter alia on the respective entry fiber angle.

8. The pressure vessel according to claim 7, characterized in that the arrangement of twists of all the twisted fiber bands is arranged on respective circles which lie concentrically with one another about the midpoint of the polar caps.

9. The pressure vessel according to claim 8, characterized in that the circles with the arrangements of twists are not arranged directly one above another.

10. The pressure vessel according to claim 1, characterized in that the outer layer at least in a central region of the polar caps due to an accumulation of material by means of the arrangement of twists has a layer thickness which is greater, preferably more than 50% greater, than that of a fiber composite layer without twisted fiber bands.

11. A method for producing a fiber-reinforced pressure vessel according to claim 1, comprising the steps: providing an inner vessel with a rotationally symmetrical, preferably cylindrical, middle part with an axis of symmetry preferably a cylinder axis, and two dome-shaped polar caps which close off the middle part; winding a fiber band made of a number of fibers in a plurality of plies with a location-dependent and position-dependent fiber orientation over the middle part and the polar caps of the inner vessel, comprising: entering the fiber band at least in some of the plies from the middle part at a respective entry fiber angle relative to the cylinder axis in the region of the polar caps; twisting the fiber band for all the fiber bands of a ply at least in the case of a portion of the plies in the region of the polar caps to produce a twist; returning the fiber band at a respective point of reversal in the reverse winding direction back in the direction of the middle part; and repeating the preceding winding steps until the outer layer of the pressure vessel made of fiber composite material made of a plurality of plies of fibers embedded in a matrix material which are arranged one above another is completed.

12. The method according to claim 11, wherein the step of twisting for each of the fiber bands of a ply which is to be twisted in the region of the polar caps is carried out through precisely 180 degrees.

13. The method according to claim 11, wherein the step of twisting takes place at the point of reversal.

14. The method according to claim 11, wherein the step of twisting is carried out such that the at least one twist of the respective fiber bands at the same entry fiber angle is/are arranged as an arrangement of twists on a circle about a geometric midpoint of the polar cap, wherein a diameter of the circle depends inter alia on the respective entry fiber angle, preferably the twists of all the twisted fiber bands of the plies to be twisted are arranged on respective circles, which lie concentrically with each other, about the midpoint of the polar caps.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0032] These and other aspects of the present invention are shown in detail in the figures as follows.

[0033] FIG. 1: an embodiment of a fiber band with a plurality of fibers.

[0034] FIG. 2: a schematic representation of a once-twisted fiber band.

[0035] FIG. 3: a pressure vessel according to the invention in the embodiment of a pressure vessel in lateral section.

[0036] FIG. 4: a schematic representation of the fiber orientation in the region of the polar cap in a top view of the polar cap.

[0037] FIG. 5: an embodiment of the method according to the invention

DETAILED DESCRIPTION OF EXAMPLES OF EMBODIMENT

[0038] FIG. 1 shows an embodiment of a fiber band FB with a plurality of fibers F, here for example with eight fibers F arranged next to one another without gaps, which are each of the same width BF. Such fibers are for example glass fibers, carbon fibers, aramid fibers or basalt fibers. The fiber band FB itself has an overall width BB of 5% and 15%, preferably between 9% and 11%, of the diameter of the middle part.

[0039] FIG. 2 shows a schematic representation of a once-twisted fiber band FB, with the fibers F being illustrated as separate lines for greater clarity. With the fiber bands FB actually used, there should be no spaces between the fibers F. With the fiber band FB twisted once through 180 degrees here, the individual fibers F of the fiber band FB swap places with each other at the point of the twist 32. An individual twist 32 here designates the turning of the fiber band FB through 180 degrees, as shown here. For example, a fiber F at the top outside in the fiber band FB once twisted through 180 degrees becomes the fiber F at the bottom outside in the fiber band FB. Correspondingly, the second fiber F from the top becomes the second fiber F from the bottom once twisted through 180 degrees, and so on.

[0040] FIG. 3 shows the pressure vessel according to the invention in lateral section, comprising an inner vessel 2 with a cylindrical middle part 21 with the cylinder axis ZA as the axis of symmetry along the middle part 21 and two dome-shaped polar caps 22 which close off the middle part 21 at both ends. In this case, the one polar cap is equipped with a valve 4 for letting gas into and out of the pressure vessel 1. On the inner vessel 2 there is wound to reinforce it an outer layer 3 made of fiber composite material FVM made of a plurality of plies of fibers F embedded in a matrix material which are arranged one above another, which plies run as a fiber band FB (see FIGS. 1 and 2) made of a number of fibers F with a location-dependent and position-dependent fiber orientation over the inner vessel 2, wherein the fiber band FB at least in some of the plies enters from the middle part 21 at a respective entry fiber angle FW relative to the cylinder axis ZA into the region of the dome-shaped polar caps 22 and there is guided at a respective point of reversal 31 in its winding direction WR back in the direction of the middle part 22, with at least a portion of the fiber bands FB in the region of the polar caps 22 having at least one twist 32. In order to obtain a desired overall stability of the outer layer 3 both in the middle part 21 and at the polar caps 22, and both against radial and against axially acting forces, the outer layer 3 here comprises both a plurality of helical plies which cover the entire pressure vessel 1 including the polar caps 22 and the middle part 21, and a plurality of peripheral plies with identical or different thicknesses, the peripheral plies being wound substantially in the middle part 21 and optionally depending on the embodiment of the polar caps 22 in the edge region 22r of the polar caps 22. The helical plies here comprise axially oriented fibers F with a fiber orientation with a small fiber angle FW for example of less than 60 degrees, preferably less than 20 degrees, to the cylinder axis ZA. In contrast to this, fibers F in the peripheral plies have a fiber direction with a fiber angle FW for example of greater than 80 degrees to the cylinder axis.

[0041] FIG. 4 shows a schematic representation of the fiber orientation in the region of a circular dome-shaped polar cap 22 in a top view of the polar cap 22. The corresponding cylindrical middle part is not shown here, see on this point FIG. 3. In this embodiment, all the fiber bands FB in the region of the polar caps 22 have a twist 32, which for reasons of clarity is illustrated schematically by two fiber bands FB. The twist 32 shown here is a twist through precisely 180 degrees, with the twists 32 illustrated being arranged at the point of reversal 31 of the respective fiber band FB. Additionally, twists 32 of the fiber bands FB (here the two fiber bands FB have the same entry fiber angle FW at the transition from the middle part 21 to the polar cap 22) are arranged as an arrangement of twists on a circle 33 about a geometric midpoint 22M of the polar cap 22, with a diameter 33D of the circle 33 depending inter alia on the respective entry fiber angle FW. In this embodiment, additionally the twists 32 of the further fiber bands FB for other entry fiber angles FB would lie on respective concentrically with each other and to the illustrated circle 33 about the midpoint 22M of the polar caps 22, which is not shown here for reasons of clarity. Due to the twists 32, the outer layer 3 at least in a central region 22z of the polar caps 22 due to an accumulation of material has a layer thickness 3D which is greater, preferably more than 50% greater, than that of a fiber composite layer FVM without twisted fiber bands FB.

[0042] FIG. 5 shows an embodiment of the method according to the invention 100 for producing a fiber-reinforced pressure vessel 1 according to the invention comprising the steps of providing 110 an inner vessel 2 with a rotationally symmetrical, preferably cylindrical, middle part 21 with an axis of symmetry ZA, preferably a cylinder axis, and two dome-shaped polar caps 22 which close off the middle part 21; winding 120 a fiber band FB made of a number of fibers F in a plurality of plies with a location-dependent and position-dependent fiber orientation over the middle part 21 and the polar caps of the inner vessel 2, comprising the following individual steps of the winding process of entering 130 the fiber band FB at least in some of the plies from the middle part 21 at a respective entry fiber angle FW relative to the cylinder axis ZA in the region of the polar caps 22; twisting 140 the fiber band FB at least for a portion of the fiber bands FB in the region [of the] polar caps 22 to produce a twist 32; returning 150 the fiber band at a respective point of reversal 31 in the reverse winding direction WR back in the direction of the middle part 22; and repeating the preceding winding steps 120, 130, 140, 150 until the outer layer 3 of the pressure vessel 1 made of fiber composite material FVM made of a plurality of plies of fibers F embedded in a matrix material which are arranged one above another is completed. In this case, the step of twisting 140 can be carried out for each of the fiber bands FB in the region of the polar caps 22 through precisely 180 degrees. In this case, the step of twisting 140 can take place at the point of reversal 31. The step of twisting 140 can be carried out such that the at least one twist 32 of the respective fiber bands FB at the same entry fiber angle FW is/are arranged as an arrangement of twists on a circle 33 about a geometric midpoint 22M of the polar cap 22, wherein a diameter 330 of the circle 33 depends inter alia on the respective entry fiber angle FW, preferably the twists 32 of all the twisted fiber bands FB are arranged on respective circles 33, which lie concentrically with each other, about the midpoint 22M of the polar caps 22. In this case, the circles with the twists preferably do not lie above one another. This firstly prevents plies of fibrous material wound over the twist, because of excessive local thickening which then results, from losing direct contact with the underlying fiber plies and thus lying thereon without cavities therebetween. Secondly, this arrangement of the twists makes it possible to fill in a concave surface profile produced over the dome-like polar cap in a targeted manner, and thereby to produce a polar-cap contour which is beneficial for the following plies.

LIST OF REFERENCE NUMERALS

[0043] 1 pressure vessel according to the invention, for example a pressure vessel [0044] 2 inner vessel [0045] 21 rotationally symmetrical middle part of the inner vessel, for example a cylindrical middle part [0046] 22 dome-shaped polar caps on the middle part [0047] 22M geometric midpoint of the dome-shaped polar cap [0048] 22z central region of the dome-shaped polar cap [0049] 22r edge region of the dome-shaped polar cap [0050] 3 outer layer made of fiber composite material [0051] 3D layer thickness of the outer layer [0052] 31 point of reversal of the respective fibers in the wound fiber orientation [0053] 32 twisting of the fibers in the polar-cap reinforcing layer [0054] 33 circle of twists [0055] 33D diameter of the circle of twists [0056] 4 valve [0057] 100 method for producing the pressure vessel according to the invention [0058] 110 providing an inner vessel of the pressure vessel [0059] 120 winding the fiber band onto the inner vessel [0060] 130 entry of the fiber band from the middle part into the region of the polar caps [0061] 140 twisting of at least a portion of the fiber bands in the polar cap region [0062] 150 repeating the preceding winding steps [0063] BB width of the fiber band [0064] BF width of the respective fibers in the fiber band [0065] F fibers of the fiber composite material [0066] FB fiber band made of a number of fibers [0067] FVM fiber composite material [0068] FW fiber angle between the respective fiber direction and the cylinder axis, for example the entry fiber angle upon entry of the fiber band from the middle part onto the polar cap [0069] ZA axis of symmetry, for example cylinder axis