Anti-static pressure tank

Abstract

A pressure tank for storing high- and low-pressure fluids/gases includes a hollow body with at least one outlet having a surrounding contact area, a boss connected to the outlet, and a static eliminator wall disposed inside the hollow body. The boss has at least one aperture extending into the interior of the hollow body and is connected over its entire surface with a complementary contact area to the contact area of the outlet. The aperture has a diffuser disposed at a bottom end thereof. The diffuser is one of part of the boss, part of a neckring, and part of a coupling piece. The diffuser seals the aperture in an axial direction and has diffuser openings pointing primarily only in a radial direction. The static eliminator wall surrounds the diffusor and is one of part of the boss, part of the neckring, and part of the coupling piece.

Claims

1. A pressure tank for storage of high and low pressure fluids/gases, including LPG, LNG or CNG, the pressure tank comprising: a hollow body of thermoplastic material with at least one outlet having a surrounding contact area; a boss connected to the outlet of the hollow body, the boss having at least one aperture extending into to the interior of the hollow body and being connected over its entire surface with a complementary contact area to the contact area of the outlet of the hollow body, the aperture having a diffuser disposed at a bottom end thereof and being one of part of the boss, part of a neckring, and part of a coupling piece, the diffuser sealing the aperture in an axial direction and having diffuser openings pointing primarily in a radial direction; and a static eliminator wall disposed inside the hollow body and surrounding the diffusor, the static eliminator wall being one of an integral part of the boss, a part of the neckring, and a part of the coupling piece.

2. The pressure tank according to claim 1, wherein the static eliminator wall is formed of a plurality of circumferentially disposed spaced-apart wall segments and has a plurality of turbulence release openings formed between the spaced-apart wall segments.

3. The pressure tank according to claim 2, wherein the turbulence release openings are elongated openings extending upwardly from a bottom edge of the static eliminator wall; and wherein the diffuser openings are aligned with either the elongated openings or aligned with respective centers of the wall segments of the static eliminator wall.

4. The pressure tank according to claim 1, wherein the static eliminator wall faces the diffuser and has one of a round contour, a waved line contour, and a polygonal contour.

5. The pressure tank according to claim 1, wherein: the diffuser openings are one of round-, oval- and polygonal-shaped openings; or the diffuser has an interior face surface in the form of one of a plane, a convex elevation, and a conical elevation; or the diffuser has a mechanism for closing the aperture of the boss during a critical flow rate of the fluid.

6. The pressure tank according to claim 1, wherein the aperture of the boss has an internal thread into which the coupling piece is screwed, the coupling piece having for sealing purposes one of at least one sealing ring and a tapered external thread.

7. The pressure tank according to claim 6, wherein the boss comprises the neckring which lies concentrically in an outer connection part of the boss and provides at least a part of the aperture and the internal thread.

8. The pressure tank according to claim 7, wherein the neckring: has one of an n-fold rotation symmetry and no symmetry, and/or has a mirror symmetry with a mirror plane, which comprises the axial direction, and/or has a surrounding collar extending in a radial direction and provided with holes, and/or has a centering groove at the top of the aperture of the boss, and/or is manufactured of metal, and/or has connecting holes and grooves.

9. The pressure tank according to claim 8, wherein the connection part of the boss: is made of a thermoplastic material; and comprises the contact area, by which it is connected over its entire surface with the complementary contact area of the outlet in the hollow body, particularly through injecting, bonding or welding by superficial liquefaction of the thermoplastic materials of the contact areas of the connection part of the boss and the outlet in the hollow body.

10. The pressure tank according to claim 9, wherein the neckring has at a bottom side thereof a neckring collar directing downwards and surrounding the aperture of the boss, the neckring collar being embedded outside in the material of the connection part of the boss so that a material of the boss between an internal side of the neckring collar and the aperture of the boss forms a sealing lip.

11. The pressure tank according to claim 10, wherein at least one sealing ring lies between the coupling piece and the sealing lip.

12. The pressure tank according to claim 11, wherein a radial thickness of the sealing lip is selected proportionally to a test pressure (P) of the pressure tank.

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

14. The pressure tank according to claim 6, wherein the difference between the height (HT) of the internal thread and the axial distance between a bottom end of the internal thread and the center of the sealing ring 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 in millimeter per winding and n.sub.T indicating the number of windings of the internal thread.

15. The pressure tank according to claim 8, wherein the neckring has a polygonal cross section.

16. The pressure tank according to claim 1, further comprising a first torque coupling formed by the contact area of the hollow body and the complementary contact area of the boss, wherein the first torque coupling has no circular symmetry regarding rotation around the axial direction of the aperture of the boss.

17. The pressure tank according to claim 16, wherein the first torque coupling has a polygonal shape.

18. The pressure tank according to claim 1, further comprising a covering layer disposed on a surface of the hollow body, the covering layer being reinforced by one or more synthetic and/or natural fibres selected from glass fibres, carbon fibres, aramid fibres, and dyneema fibres, the fibres being embedded in a matrix formed of one of thermal and UV-curable resins, and the surface of the hollow body on which the covering layer is disposed being provided with a treatment that increases a connection between the covering layer and the hollow body.

19. The pressure tank according to claim 18, further comprising a second torque coupling integrally formed into the covering layer in an area of the outlet of the hollow body, the second torque coupling having an n-fold rotation symmetry for transferring a torque applied to the boss to the covering layer.

20. The pressure tank according to claim 19, wherein the second torque coupling has a polygonal shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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. In schematic representation are shown:

(2) FIG. 1a is a partial cross-sectional view of the pressure tank according to an embodiment of the present invention showing a static eliminator wall with turbulence release openings at a boss and an integral diffuser of a coupling piece.

(3) FIG. 1b is a section of the bottom part of the boss shown in FIG. 1a.

(4) FIG. 2 is a bottom perspective view from an angle of the boss shown in FIG. 1a.

(5) FIG. 3a is a bottom perspective view from an angle of the pressure tank according to another embodiment of the present invention.

(6) FIG. 3b is a partial cross-sectional view of the pressure tank in FIG. 3a showing the boss with integral diffuser.

(7) FIG. 4 is a graph illustrating the relation between test pressure and sealing lip thickness in a radial direction.

(8) FIG. 5 is a partial cross-sectional view of a pressure tank according to a further embodiment of the present invention showing a boss with a contoured diffuser face surface.

(9) FIG. 6 is a partial cross-sectional view of the pressure tank according to a further embodiment of the present invention showing a boss and coupling piece with static eliminator wall belonging to the latter and a diffuser.

(10) FIG. 7 is a bottom perspective view from an angle of a pressure tank according to a further embodiment of the present invention showing a coupling piece with static eliminator wall and a diffuser.

(11) FIG. 8a is a partial cross-sectional view of the pressure tank according to a further embodiment of the present invention showing a boss with integral pressure relief device in the diffuser (closed position).

(12) FIG. 8b is a view similar to FIG. 8a but showing a pressure relief device in the open position.

DETAILED DESCRIPTION OF THE EMBODIMENTS

(13) FIG. 1a 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.

(14) 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.

(15) 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.

(16) 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.

(17) 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.

(18) FIG. 1b 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−DO≤0.5 TP, TP standing for the thread pitch of the internal thread 25.

(19) 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 diffuser 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.

(20) In FIGS. 3a and 3b a further preferred embodiment of the boss of the pressure tank of the present invention is illustrated. The upper section figure (FIG. 3a) 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.

(21) The lower section figure (FIG. 3b) 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.

(22) 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.

(23) 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.

(24) 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.

(25) 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.

(26) FIG. 8a 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. 8b. 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

(27) 1 Hollow body 11 Outlet in hollow body 1 111 Contact area 12 Joint between hollow body and boss 13 Interior of the hollow body 2 Boss 20 Boss part 21 Aperture 22 Diffuser 221 Diffuser opening 222 Inner face surface of the diffuser with elevation 23 Neckring 231 Neckring collar 232 Neckring flange 233 Neckring holes 234 Centering groove 24 Sealing lip 25 Internal thread 26 Contact area 27 Static eliminator wall 271 Inner static eliminator wall surface 28 Turbulence release opening 3 Coupling piece 31 Sealing ring 8 Fibre-reinforced layer 81 Torque coupling 9 Pressure relief device P Test pressure D Sealing lip thickness, radial Dmin Minimum recommended sealing lip thickness Dmax Maximum recommended sealing lip thickness TP Thread pitch HT Thread height DO Sealing ring distance to the bottom thread margin