IMPROVED ANTI-STATIC PRESSURE TANK

Abstract

Pressure tank for storage of high and low fluids/gases, particularly LPG, LNG or CNG, comprising a hollow body (1) of thermoplastic material with at least one outlet (11), which has a surrounding contact area (111), one boss (2) each per outlet (11), which has at least one aperture (21) each to the interior (13) of the hollow body (1) and which is connected by a complementary contact area (26) over its entire surface with contact area (111), whereas the aperture (21) has a diffuser (22) at a bottom end, sealing the aperture (21) in an axial direction and comprising only openings (221), which point primarily in radial direction, comprising a static eliminator wall (27) around the diffuser (22) inside the hollow body (1), whereas the static eliminator wall (27) is a part of the boss (2) or the neckring (23) or is fixed as a separate part on coupling piece (3).

Claims

1. Pressure tank for storage of high and low pressure fluids/gases, particularly LPG, LNG or CNG, comprising a hollow body (1) of thermoplastic material with at least one outlet (11), having a surrounding contact area (111), one boss (2) each per outlet (11), having at least one aperture (21) to the interior (13) of the hollow body (1) and being connected over its entire surface with a complementary contact area (26) to the contact area (111), the aperture (21) having a diffuser (22) at a bottom end, which can be part of the boss (2), or of a neckring (23) or of a coupling piece (3), and which seals the aperture (21) in axial direction and has diffuser openings (221) pointing primarily only in radial direction, a static eliminator wall (27) inside the hollow body (1), surrounding the diffusor (22), characterized in that the static eliminator wall (27) is part of the boss (2) or of the neckring (23) or is fixed as a separate part to the coupling piece (3).

2. Pressure tank according to claim 1, characterized in that the static eliminator wall (27) has several turbulence release openings (28), which are positioned relatively to the diffuser openings (221) in such a way, that fluid, which flows in under pressure, creates a primarily stationary flow in the area below the boss (2).

3. Pressure tank according to claim 2, characterized in that the turbulence release openings (28) are elongated openings, beginning at the bottom edge of the static eliminator wall (27) and extending above an essential part of its height, and/or are aligned with the radial openings (221) of the diffuser (22), or are aligned with the opposite integrated-segments of the static eliminator wall (27), particularly with their respective centre.

4. Pressure tank according to claim 1, characterized in that the static eliminator wall (27) has a round contour or a more complex contour, e.g. a waved line contour or a polygonal contour along its surface (271) which is facing the diffuser (22).

5. Pressure tank according to claim 1, characterized in that diffuser (22) has round, oval or polygonal, particularly rectangular diffuser openings (221), or has an interior face surface (222), which is plane or has a more complex topography, particularly a convex or conical elevation, or has a mechanism (9), which closes aperture (21) during a critical flow rate of the fluid.

6. Pressure tank according to claim 1, characterized in that the aperture (21) of the boss (2) has an internal thread (25), into which a valve or other coupling piece (3) is screwed, having for sealing purposes at least one sealing ring (31), or a tapered external thread.

7. Pressure tank according to claim 6, characterized in that the boss (2) comprises an injected or embedded neckring (23), which lies concentrically in an outer connection part (20) of the boss (2) and provides at least a part of the aperture (21) and the internal thread (25).

8. Pressure tank according to claim 7, characterized in that the neckring (23) has a reduced symmetry compared to circular symmetry, in regard to the rotation around the axial direction of the aperture (21), particularly an n-fold rotation symmetry, for example a polygonal cross section, or no symmetry, and/or a mirror symmetry with a mirror plane, which comprises the axial direction, and/or has an surrounding collar (232), extending in radial direction, with holes (233) in it, and/or has a centering groove (234) at the top of the aperture (21), and/or is manufactured of metal, and/or has connecting holes and grooves.

9. Pressure tank according to claim 8, characterized in that the connection part (20) is manufactured from a thermoplastic material, and comprises contact area (26), by which it is connected over its entire surface with the complementary contact area (111) of the outlet (11) in the hollow body (1), particularly through injecting, bonding or welding by superficial liquefaction of the thermoplastic materials of the contact areas (111) and (26) and the following compression.

10. Pressure tank according to claim 9, characterized in that the neckring (23) has at the bottom side a neckring collar (231) directing downwards and surrounding the aperture (21), such collar being embedded outside in the material of the connection part (20), so that the boss (2) material between the internal side of the neckring collar (231) and the aperture (21) forms a sealing lip (24).

11. Pressure tank according to claim 10, characterized in that at least one sealing ring (31) lies between coupling piece (3) and sealing lip (24).

12. Pressure tank according to claim 11, characterized in that a radial thickness of the sealing lip (24) is selected proportionally to a test pressure of the pressure tank (1).

13. Pressure tank according to claim 12, characterized in that the radial thickness of the sealing lip (24) is selected between a minimum thickness (Dmin) and a maximum thickness (Dmax), these thicknesses being linked with the test pressure (P) by the following relations:
Dmax(mm)=0.01 P(bar)+3.0
Dmin(mm)=0.019 Dmax(mm)+2.95.

14. Pressure tank according to claim 1, characterized in that the contact areas (26, 111) for transferring the torques from the boss (2) onto the hollow body (1) has as torque coupling no circular symmetry regarding rotation around the axial direction of the aperture (21) and has particularly an n-fold rotation symmetry, for example a polygonal shape.

15. Pressure tank according to claim 1, characterized in that a further layer (8) is wound around the hollow body (1), reinforced by fibres, particularly glass fibres, carbon fibres, aramid fibres, dyneema fibres, other synthetic fibres and/or natural fibres and comprising additionally a matrix embedding the fibres, particularly out of thermally or UV-curable resins or other resins, with a further treatment of the hollow body (1) surface, that has taken place in particular before the application of the reinforcement layer.

16. Pressure tank according to claim 15, characterized in that a second torque coupling (81) is integrally formed into the fibre-reinforced layer (8) in the outlet (11) area, such coupling having a shape of non-circular symmetry, particularly with n-fold rotation symmetry or a polygonal shape for the purpose of transferring the torques affecting the boss (2) into the layer (8).

17. Pressure tank according to claim 6, characterized in that the difference between the height (HT) of the internal thread (25) and the axial distance between a bottom end of the internal thread (25) and the center of sealing ring (31) follows the relation
HT(mm)DO(mm)0.5 TP and
HT (mm)=n.sub.T TP (mm) is still valid, (TP) being a pitch of the internal thread (25) in millimeter per winding and n.sub.T indicating the number of windings of the internal thread (25).

Description

[0043] Further specified details and characteristics of the invention shall be explained below with illustrated embodiments. These shall however not limit the invention, but only explain it.

[0044] In schematic representation are shown:

[0045] FIG. 1: Cross-section through an embodiment of the pressure tank of the present invention with static eliminator wall with turbulence release openings at the boss and an integral diffuser of a coupling piece

[0046] FIG. 1a: Enlarged section of the bottom part of the boss from FIG. 1

[0047] FIG. 2: Perspective view from an angle below onto the boss from FIG. 1

[0048] FIG. 3: Perspective view from an angle below and cut-away view of a further embodiment of the boss with integral diffuser

[0049] FIG. 4: Relation between test pressure and sealing lip thickness in radial direction

[0050] FIG. 5: Cross-section of a further embodiment of the boss with contoured diffuser face surface

[0051] FIG. 6: Cross-section of a further embodiment of boss and coupling piece with static eliminator wall belonging to the latter and diffusor

[0052] FIG. 7: Perspective view from an angle below onto a further embodiment of the coupling piece with static eliminator wall and diffuser

[0053] FIG. 8: Cross-section of a further embodiment of the boss with integral pressure relief device in the diffuser (closed position)

[0054] FIG. 8a: Cross-section through the boss of FIG. 8 with open pressure relief device

[0055] FIG. 1 illustrates a cross-section through an outlet of a pressure tank according to the present invention with mounted boss. Boss 2 is connected tightly into outlet 11, whereupon the complementary contact areas 26 and 111 form a torque coupling for the constant and effective transmission of the torque from boss 2 onto hollow body 1. Another torque coupling is formed by the contact areas between boss part 20 of boss 2 and the fibre-reinforced layer 8, which covers hollow body 1 and partly boss part 20. The boss 2 has two parts and consists of an outer boss part 20 and its integral neckring 23, which has an internal thread 25, for screwing the coupling piece 3 into boss 2. During the manufacturing process, particularly in an automated manner by an assembling robot, the handling and positioning of coupling piece 3 is facilitated by the centering groove 234 at the upper end of the internal thread 25. At the bottom end of aperture 21 the diffuser 22 is an integral part of the coupling piece 3.

[0056] Diffuser 22 serves for the deceleration and redirection of a fluid flowing in under high pressure, by closing aperture 21 in axial direction and comprises only openings 221 in radial direction. The fluid, which flows in radially after having passed through the diffuser openings 221, hits the static eliminator wall 27 around the diffuser 22 with a lower velocity, compared to a theoretical flow rate without diffuser, such static eliminator wall is formed as cylinder collar which is interrupted by turbulence release openings 28, here designed as elongated grooves. Static eliminator wall 27 is an overhang of the outer boss part 20 in axial direction and is therefore an integral part of boss part 20. Diffuser 2 has a mirror- and rotation-symmetric design with a 6-fold rotation symmetry in this embodiment, so that the coupling piece remains force- and torque-free during the filling process. The same applies also to static eliminator wall 27.

[0057] This secures an essential improvement of the present invention, particularly that the joint 12 between hollow body 1 and boss 2 lies outside the space between diffuser 22 and static eliminator wall 27. Thus it is advantageously avoided, that the fluid flowing in under high pressure is pressed into the joint due to the high static counter pressure, which is built up in the said space in between, perhaps together with the dynamical pressure of the fluid, which hits under high pressure the boundary surface of the space in between, thus permanently compromising the tightness of the pressure tank during the filling process or in the worst case during plastic deformation.

[0058] This is promoted by the fact that only a small counter pressure is built up in the said space, as the turbulence release openings 28 create an additional outflow path. When flowing through the openings 28 the fluid is thus dispersed into a fog of fine droplets, which minimizes the risk of a static charge of areas which are in a greater distance from outlet 11.

[0059] The tightness of the described pressure tank of the present invention is advantageously guaranteed farther, during the filling process as well as in a pressure-filled state, by a dimensioning of the radial thickness of sealing lip 24, which is located between a neckring collar 231, which is extending downwards from the neckring 23 in radial direction and sealing ring 31 of the coupling piece 3, increasing proportionally with the intended test pressure, i.e. maximum pressure of the tank.

[0060] FIG. 1a illustrates an enlarged section of the bottom half of boss 2 respectively of the bottom end of aperture 21. The difference of height HT of the internal thread 25 and distance DO between bottom edge of internal thread 25 and O-ring 31 is chosen according to the relation HT-DO0.5 TP, TP standing for the thread pitch of the internal thread 25.

[0061] FIG. 2 illustrates a perspective view from an angle below onto the boss of FIG. 1. It shows the hexagonally shaped contact area 26, which forms a torque coupling for the transmission of torque from boss 2 onto the hollow body of the pressure tank, with the complementary contact area of the outlet of the hollow body, into which boss 2 is mounted and welded or bonded. Coupling piece 3, which comprises at its bottom end the diffusor 22, which forms a flow obstacle in axial direction, is screwed to the internal thread of the not visible neckring 23. Coupling piece 3 is screwed to such an extent, that the diffuser openings 221, which are extending in radial direction, align approximately with turbulence release openings 28 in the static eliminator wall 27. Thus, a high flow rate is achieved during the filling process, however at the same time also a still good antistatic effect by the appropriate narrow dimensioning of the turbulence release openings 28 in the width. Such effect is however optimized, when the diffuser openings 221 do not align with the turbulence release openings 28, but face the continuous ones of the static eliminator wall 27, so that fluid, which flows out of the openings 221, hits these and is farther slowed down. In this case nearly all loads, which are carried away from the coupling piece 3 or the diffuser 22, are deposited in the static eliminator wall 27, from where they are directed away by droplets to the coupling piece 3 respectively diffuser 22, as static eliminator wall 27 is part of the boss 2, which can be designed relatively more conductive, and not of the non-conducting hollow body 1.

[0062] In FIG. 3 a further preferred embodiment of the boss of the pressure tank of the present invention is illustrated. The upper section figure shows a perspective view from an angle below, stating that the diffuser openings 221 are aligned relatively to the static eliminator wall 27 with the turbulence release openings 28 in such a way, that the fluid jet, which flows out of the openings 221, hits exactly centrically the massive static eliminator wall segments 27. Like the embodiment illustrated in the FIGS. 1-2, the diffuser 22 has also a mirror- and 6-numbered rotation symmetry.

[0063] The lower section figure illustrates a cut-away section of the boss 2. It can be seen that this is also formed from two parts, the outer boss part 20 and neckring 23. In turn, neckring 23 comprises an internal thread 25 for mounting a hose, tube, valve or other coupling piece. The essential difference to the previous embodiment is, that diffuser 22, as clearly visible in this section figure, forms an integral part of boss 2, particularly boss part 20. Thus, it is avoided that the relative alignments of the diffuser openings 221 with the static eliminator wall 27 and the turbulence release openings 28, may differ with each screw process.

[0064] FIG. 4 shows in a graph the relation the present invention recommends between the radial thickness D of sealing lip 24 and the requested test pressure. The sealing lip thickness is represented on the y-axis, the pressure on the x-axis. The course is strictly increasing in a straight line with a proportionality constant (slope) of 0.01 mm/bar in case of the recommended maximum thickness Dmax and 0.019 mm/bar in case of the minimum recommended thickness Dmin. The axis intercepts at 100 bar are 3.03 mm respectively 4.0 mm with minimum respectively maximum recommended thickness. The radial thickness D for the specified test pressure P should therefore lie between Dmin and Dmax, in order to guarantee optimum tightness.

[0065] FIG. 5 illustrates a further advantageous embodiment of the boss 2 of the pressure tank of the present invention, which has on the inner face surface 222 of the diffuser a truncated cone shaped elevation facing the flow direction of the inflowing fluid for the modification of the flow conditions. The lateral neckring flange 232 stabilizes the neckring 23 for axial loads. Neckring holes 233 are inserted in it, into which the liquid thermoplastic material of the boss can flow during the manufacturing process.

[0066] FIG. 6 illustrates an embodiment, in which the diffuser 22 as well as the static eliminator wall 27 form a part of the coupling piece 3. This offers the special advantage, that the static eliminator wall 27 as highly stressed component can easily be made accessible for service or exchange measures, by dismounting the coupling piece 3.

[0067] FIG. 7 illustrates an embodiment of the static eliminator wall 27 and the diffuser 22, in which the turbulence release openings 28 of the static eliminator wall taper radially and show a polygonal contour. Such shaping of the turbulence release openings and appropriate contours on the inner surface of the static eliminator wall, which faces the diffuser 22, represent a possibility, to explicitly direct the fluid flow and also to influence the material wear of the static eliminator wall 27 itself.

[0068] FIG. 8 illustrates an embodiment of the diffuser 22 with integral pressure relief device 9, which is shown here in closed position. A complementary illustration of the pressure relief device 9 in an open position is shown in FIG. 8a. In case of a sudden pressure loss on the outlet side and therefore flow increase during the fluid unloading, for example when a line bursts, the pressure relief device is drawn along and closes the outlet above the diffuser openings 221.

LIST OF REFERENCE NUMERALS

[0069] 1 Hollow body

[0070] 11 Outlet in hollow body 1

[0071] 111 Contact area

[0072] 12 Joint between hollow body and boss

[0073] 13 Interior of the hollow body

[0074] 2 Boss

[0075] 20 Boss part

[0076] 21 Aperture

[0077] 22 Diffuser

[0078] 221 Diffuser opening

[0079] 222 Inner face surface of the diffusor with elevation

[0080] 23 Neckring

[0081] 231 Neckring collar

[0082] 232 Neckring flange

[0083] 233 Neckring holes

[0084] 234 Centering groove

[0085] 24 Sealing lip

[0086] 25 Internal thread

[0087] 26 Contact area

[0088] 27 Static eliminator wall

[0089] 271 Inner static eliminator wall surface

[0090] 28 Turbulence release opening

[0091] 3 Coupling piece

[0092] 31 Sealing ring

[0093] 8 Fibre-reinforced layer

[0094] 81 Torque coupling

[0095] 9 Pressure relief device

[0096] P Test pressure

[0097] D Sealing lip thickness, radial

[0098] Dmin Minimum recommended sealing lip thickness

[0099] Dmax Maximum recommended sealing lip thickness

[0100] TP Thread pitch

[0101] HT Thread height

[0102] DO Sealing ring distance to the bottom thread margin