High-pressure composite vessel and the method of manufacturing high-pressure composite vessel

Abstract

A hight-pressure composite vessel comprising a casing fabricated through blow-moulding a preform of thermoplastic, a connection pipe fitting. In the connection connection pipe fitting (3) with a retaining collar (7), opposite to a sealing groove (9) designed for an o-ring seal, there is a groove (10) for a seeger to mount a non-detachable collar (11a) of the preform (11) by way of the seeger (10a). A method of manufacturing the high-pressure composite vessel under which the casing of the vessel is fabricated of a perform that is blow-moulded so as to obtain the required dimensions thereof, whereas the preform of a thermoplastic material is fabricated using any technology; and the casing of the vessel is connected with the connection pipe fitting, and the external surface of the vessel re reinforced by a special composite layer. The preform (11) first undergoes a process of controlled crystallization and, then, the ring-shaped groove (11b) is made in the collar (11a) of the preform (11).

Claims

1. A high-pressure composite vessel comprising a casing (1) producible through blow moulding a thermoplastic material of a preform and integral with a preform collar (11a), a connection fitting (3), with a retaining collar (7), an o-ring seal (9a) mounted in a sealing groove (9) shaped in the connection fitting (3), and a Seeger ring (10a) mounted in a fixing groove (10) shaped in the connection fitting (3) opposite to the sealing groove (9), said Seeger ring (10a) is fixing the preform collar (11a) in the connection fitting (3), characterized in that an annual groove (11b) is shaped in the external side of the preform collar (11a), and said annular groove (11b) is facing the fixing groove (10) shaped in the connection fitting (3) after mounting the casing (1) to the connection fitting (3), and in that the sealing groove (9) is facing the inner cylindrical side of the preform collar (11a).

2. The composite vessel according to claim 1, characterized in that the cross-section of the Seeger ring (10a) is trapezoidal with a right angle.

3. The composite vessel according to claim 1, the casing (1) with the preform collar (11a) is made of polyethylene terephthalate (PETE) or polyamide.

4. The composite vessel according to claim 1 characterized in that the casing (1) is reinforced with external composite layer (2), and in that this composite layer (2) is made in the form of a braiding of bundles of carbon-aramid filaments and of epoxy resin.

5. The composite vessel according to claim 4 characterized in that the bundle of filaments is formed using two outer carbon filaments and one inner aramid filament.

6. The composite vessel according to claim 1, characterized in that it has a bottom unit (4) with arched-convex, branched wings (5) fitting to an arched-concave bottom of the casing (1), and in that the connection fitting (3) has an external annular boss (8) around the opening of the connection fitting (3), while the bottom unit (4) has additional annular bosses (6) placed inside a reinforcing composite layer (2).

7. A high-pressure composite vessel comprising a casing (1) producible by blow-moulding a preform (11) to required dimensions, said casing (I) being connected with a connection fitting (3), and externally reinforced by a composite layer (2), and where the preform is made of thermoplastic material, characterized in that the preform (11) first undergoes a process of controlled crystallization so that thermoplastic material of the casing (1) is a crystallized thermoplastic material, and then an annular groove (11b) is made in the preform collar (11a) so that the preform collar (11a) retained in the composite vessel has the annular groove (11b), and subsequently the preform (11) is blow-moulded to required dimensions and assembled with the connection fitting (3) equipped with a retaining collar (7) so that the composite vessel has the connection fitting (3) equipped with the retaining collar (7) and an o-ring seal (9a) placed in a sealing groove (9) in the connection fitting (3), and a Seeger ring (10a) placed in a fixing groove (10) in the connection fitting (3), and the connection fitting (3) is put and clamped onto the preform collar (11a) of the casing (1), and then the vessel is filled with gas until the pressure inside the vessel becomes constant, and a composite layer (2) is fabricated by braiding the bundles of reinforcing filaments according to three winding patterns: helical, polar, and hoop, and then the reinforcing composite layer (2) is thermally hardened, so that the casing (1) of the composite vessel is covered by the thermally hardened composite layer (2) consisting of the bundles of reinforcing filaments arranged according to three winding patterns: helical, polar, and hoop.

8. The composite vessel according to claim 7, characterized in that the crystallization process of the preform collar (11a) is isolated from the rest of the preform (11) and is run in the following way: the preform collar (la) is gradually heated to a temperature close to a mid-point between the glass transition temperature and the melting point temperature for 8 to 10 minutes, then plastified preform collar (11a) is placed on a metallic cylindrical mandrel with a cross-section diameter equal to the inner diameter of the connection fitting (3), and then the preform collar (11a) is gradually cooled in a bath wash for 4 to 10 minutes, so that the preform collar (11a) retained in the composite vessel is crystallized.

9. The composite vessel according to claim 8, characterized in that the temperature of the heated preform collar (11a) is in a range between 135 C. and 165 C., and the heating process continues for 5 to 6 minutes, whereas the process of gradual cooling of the preform collar (11a) in the bath wash continues for 5 to 6 minutes.

10. The composite vessel according to claim 7, characterized in that after the crystallization process of the preform collar (11a) is completed, the annular groove (11b) is shaped on the outer side of the preform collar (11a) so that the annular groove (11b) on the outer side of the preform collar (11a) is facing the fixing groove (10) in the connection fitting (3) after the casing (1) is assembled with the connection fitting (3), and the o-ring seal (9a) mounted in the inner sealing groove (9) meets the inner cylindrical side of the preform collar (11a).

11. The composite vessel according to claim 7, characterized in that the thermosetting resins as well as fibres are used to produce the composite layer (2), so that the composite layer (2) consists of the thermosetting resins and fibres.

12. The composite vessel according to claim 11, characterized in that the thermosetting resins are epoxy resins, and in that the fibres are a bundle of carbon and aramid filaments, composed of two outer carbon filaments and one inner aramid filament.

13. The composite vessel according to claim 7, characterized in that the braiding is made according to helical-polar winding pattern, i.e. the bundles of filaments are wound each time the winding mandrel passes between the poles of the vessel and rotates about the connection fitting (3), and the angle of inclination of the rotation axis is maintained constant, between 53 and 55.

14. The composite vessel according to claim 13, characterized in that the process of the filaments winding continues at a constant pressure ranging between 2 and 2.8 bar inside the vessel, and in that the pressure value inside the vessel is inversely proportional to the vessel size.

15. The composite vessel according to claim 14, characterized in that the composite layer (2) is fabricated through successive winding and finally has 10 to 12 wraps of the filament bundles, namely up to four wraps according to the polar winding pattern, up to three wraps according to the helical winding pattern, up to three wraps according to the hoop winding pattern, and one outer wrap according to the polar winding pattern.

16. The composite vessel according to claim 15, characterized in that while winding the filaments, the vessel is brought to vibrate slightly.

17. The composite vessel according to claim 16, characterized in that the temperature during the hardening process is stepwise increased from 20 C. to 70 C. at preset time intervals, and while the vessel slowly rotates about its axis, and in that at first stage of the hardening process the vessel is maintained at a temperature of 20 C.+/2 C. for a period of time of 24 hrs+/2 hrs, than in second stage at a temperature of 45 C.+/2 C. for a period of time not exceeding 72 hrs+/2 hrs from the beginning of hardening, and at third stage the temperature is increased to 70 C.+/2 C. and kept constant for 34 hrs+/2 hrs, and at fourth stage, the temperature is decreased to 23 C.+/2 C. and the vessel remains at this temperature for 12 hrs+/2 hrs.

Description

(1) The vesselsubject of this Inventionis exemplified by one embodiment depicted in the Drawing comprising several Figures:

(2) FIG. 1 shows a longitudinal section of the composite high-pressure vessel;

(3) FIG. 2 shows a longitudinal section of the liner with the connection pipe fitting;

(4) FIG. 3 shows a longitudinal section of the liner;

(5) FIG. 4 shows a longitudinal section of the connection pipe fitting;

(6) FIG. 5 shows a longitudinal section of the o-ring sealing;

(7) FIG. 6 shows a longitudinal section of the seeger;

(8) FIG. 7 shows a longitudinal section of the preform;

(9) FIG. 8 illustrates a polar winding pattern;

(10) FIG. 9 illustrates a helical winding pattern;

(11) FIG. 10 shows a hoop (or girth) winding pattern.

EXAMPLE: 1

(12) The composite high-pressure vessel acc. to the Invention consists of a casing 1, fabricated from a blow-moulded preform 11 equipped with a collar 11a and a composite layer 2, reinforced with a load-bearing wound wrap made of high-modulus carbon and aramid fibres, and of a connection pipe fitting 3 made of aluminium.

(13) The preform is made of polyethylene terephthalate (PETE) or polyamide.

(14) As shown in FIG. 1, inside the casing 1, opposite to the connection pipe fitting 3, there is a reinforcing bottom unit 4 made of aluminium and fixed within the composite layer of the vessel. Where the bottom unit 4 contacts the bottom of the vessel, it is shaped as arched-convex, branched wings 5 that stick to the arched-concave bottom of the casing; the unit is also equipped with additional, ring-shaped bosses 6 mounted inside the composite layer. The connection pipe fitting 3 is manufactured as one whole element and equipped with a retaining collar 7 designed to rest on the external part of the casing; above the retaining collar there is one extra ring-shaped boss 8 placed around the opening of the connection pipe fitting.

(15) On the circumference of the inner part of the connection pipe fitting, there is a ring-shaped sealing groove 9 with an o-ring seal 9a mounted therein, and, also, a groove 10 in a seeger 10a that protects against axial shifts that might occur as a result of forces acting on the composite vessel.

(16) The connection pipe fitting 3 is connected with the casing 1 manufactured while blow-moulding the preform 11; in the upper part of the preform 11, there is a collar 11a with a ring-shaped groove 11b manufactured so that as soon as the casing 1 is connected with the connection pipe fitting 3, the outer ring-shaped groove 10 in the connection pipe fitting 3 exactly faces the groove 11b in the collar of the preform 11, and the inner sealing groove 9 with an o-ring seal 9a mounted in the groove is seated exactly in the cylindrical part of the collar 11a of the preform 11.

EXAMPLE: 2

(17) The first stage of the method of manufacturing a composite high-pressure vessel acc. to the Invention consists in that the collar of the preform 11 undergoes a topical crystallization process. The length of the collar 11a of the preform 11 equals the length of the connection with the connection pipe fitting 3. Prior to launching the topical crystallization, the collar 11a of the preform 11 is isolated from the other part of the preform 11 in order to avoid a phenomenon of uncontrolled spreading of the crystallization. The crystallization process consists of gradually heating up the collar 11a for, preferably, 6 minutes, to reach a temperature close to a mid-point between the glass transition and melting temperature. After the heating up is completed, the pliable collar of the preform is placed on a metallic cylindrical mandrel and cooled, step by step, in a bath wash for, preferably, 6 min, and the cross-section diameter of the mandrel used while cooling the preform equals the inner diameter of the connection pipe fitting. The effect of the accomplished crystallization process is that the produced structure of the collar is crystalline-amorphous.

(18) Upon the completion of the topical crystallization process, a ring-shaped groove 11b is made on the outer surface of the collar 11a of the preform, and this groove is made so that, as soon as the liner 1 is connected with the connection pipe fitting 3, the groove 11b faces exactly the outer ring-shaped groove 10 of the connection pipe fitting 3, and the sealing groove 9 with the o-ring sealing seal 9a mounted in the groove 9 is seated exactly in the cylindrical part of the collar 11a of the preform.

(19) At the subsequent stage of the method acc. to the Invention, the pre-prepared preform 11 with the collar 11a, that underwent the controlled crystallization process and which has a ring-shaped groove 11b, is blow-moulded using a well-know technology and the preform obtained a required shape and necessary dimensions; next, the ready preform is mounted together with the connection pipe fitting 3, equipped with a retaining collar 7 and with the bottom unit 4. The vessel fabricated is filled in with gas until a required constant gas pressure value of 2 bar is obtained; thereafter, the entire vessel is coated with a reinforcing composite layer 2 (inner fibre).

(20) The composite layer is fabricated by winding a bundle of filaments impregnated with resin, preferably epoxy resin, via a wet filament winding technology with the use of three winding patterns: helical, polar, and hoop winding as presented in FIGS. 6 to 8 on the Drawing.

(21) Preferably, the sequence of winding bundles of filaments is as follows: four wraps wound acc. to the polar pattern; three wraps made acc. to the helical pattern; three wraps wound acc. to the hoop pattern; and one wrap made acc. to the polar pattern.

(22) In helical winding, the bundle of filaments is wound and, at the same time, the vessel or the winding mandrel rotates and is moved along the entire length of the vessel, at an angle of inclination of the rotation axis being, preferably 54. The helically wound wraps ensure the best operational effect of the reinforcement filaments. While the winding continues, the vessel is brought to vibrate slightly; the vibrations enhance the arrangement of the filaments on the liner and eliminate void spaces in the composite material.

(23) When applying a polar winding pattern to wind filaments, the bundle of filaments is wrapped as the winding mandrel passes from pole to pole of the vessel, and, simultaneously, the bundle of filaments passes around the connection pipe fitting and, so, it becomes an element to fix the connection pipe fitting.

(24) After the composite layer consisting of 10 to 12 wound wraps of filaments is fabricated, the vessel undergoes a hardening process: the temperature is gradually increased at regular, fixed intervals over a period of time while the vessel rotates slowly about its axis. At the first stage of the hardening process, the vessel is kept at a temperature of 20 C. for a 24 hour period. During this time, polymers are cross-linked and, as a result, the rigidity increases as does their weather-, radiation-, and temperature-resistance. After cross-linking, the temperature rises gradually and, as a result, the thermal strength is increased to 46 C. Next, the temperature rises to 45 C. and the vessel is kept at this temperature for max 24 hrs. Then again, the temperature rises to 70 C. and is maintained for another 24 hrs. Finally, the temperature drops to 23 C. during a period of 12 hours. The thermal strength obtained during the hardening process according to the Invention is 82 C.

(25) At the final stage of manufacturing the composite vessel according to the Invention, the vessel is coated by an additional protective layer to protect it against UV, water, chemical substances, and, additionally, to increase its impact strength.

(26) The composite vessel acc. to the Invention is characterized by excellent mechanical properties (high deformation resistance, high fatigue strength, and high impact strength).