TWI853791B - Improved antistatic pressure tank - Google Patents

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 outlet 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 boss contact area (26) over its entire surface with outlet 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).

Description

Improved anti-static pressure tank

The invention relates to a pressure tank for storing high-pressure and low-pressure liquids/gases, in particular liquefied petroleum gas (LPG), liquefied natural gas (LNG) or compressed natural gas (CNG), comprising a hollow body of thermoplastic material with at least one outlet, having a surrounding contact area, each outlet having a boss having at least one aperture leading to the interior of the hollow body and connected to the contact area over the entire space of a complementary part, at a bottom end the aperture having a diffuser, sealing the aperture in the axial direction and having several openings directed mainly only in the radial direction, wherein an electrostatic eliminator wall inside the hollow body surrounds the diffuser.

In the prior art, tanks for storing gases or liquids at low or high pressure, such as liquefied petroleum gas (LPG) or liquefied natural gas (LNG) or compressed natural gas (CNG), are known. Such tanks are made of thermoplastic material, in particular in a blow moulding, rotation moulding, PET blowing process or injection moulding process. To increase the compressive strength, the tanks are covered in a second step with an outer layer of resilient fibres, which are usually embedded in a resin, which bonds the fibres to each other and fixes them to the inner plastic layer.

Regardless of the embodiment, such a groove must in any case be provided with at least one boss on which a pressure-tight connection, such as a valve, hose or pipe end, is mounted in order to fill or empty the groove. The connection between the boss and the connection can be achieved by a latch-locked plug or a bayonet socket, however, for high-pressure applications screw plugs with low thread pitches are mainly used.

The inner part of the hollow body, also called the lining, can be made of metal, such as aluminum, titanium or steel, but, as mentioned in the opening section, can also be made of plastic, such as thermoplastic materials. Such thermoplastic materials have the advantage that they can be molded more easily and therefore have lower manufacturing costs, and that their coefficient of thermal expansion is more suitable for the matrix of the fiber-reinforced outer layer, which is usually a resin. However, the disadvantages are lower pressure resistance compared to metal linings, considerable wall thickness and lower temperature resistance. However, depending on the application, these advantages are secondary to the above advantages.

Another disadvantage of plastic linings, which is an important factor in the present invention, is that they have low electrical conductivity and therefore tend to generate static charges when filled with liquid flowing at high pressure. The liquid flows out of the outlet of the usually metal filling valve at high speed, thus carrying away electrons, which then deposit at the impact point when impacting the inner tank wall. In addition, charge separation can be generated by a fluid jet that hits the opposite side of the inner wall at high speed.

In hollow bodies or linings made of metal or other electrically conductive materials, charge equalization can be carried out quickly and easily. To increase safety further, the hollow body/lining as well as the valve can also be grounded. This is not possible or hardly possible with plastic linings, such as thermoplastics, respectively, because of their poor electrical conductivity. This leads to electrostatic charging of the hollow body/lining, which can be released in a practically flash and unpredictable manner. If there is still residual oxygen in the tank or the filling liquid (mixture) itself is flammable, an explosion may occur. This problem occurs first during the filling of empty and dry pressure tanks, since the release of the generated electrostatic charge hardly occurs and inert gas treatment should not be carried out before this when oxygen is still available.

As a prior art, two solutions have been proposed for this problem, which can be summarized as keyword elimination and prevention. The two solutions are exemplified in patent US 7,656,642 B2 (Ulekleiv et al.).

Solutions for elimination are proposed, for example, to improve the conductivity of the inner tank wall by means of a conductive coating in addition to the non-conductive or almost non-conductive plastic material. However, this solution has the disadvantage that the advantages of the easier and low-budget manufacturing process of the thermoplastic lining are therefore at least partially excluded again. Moreover, such coatings wear out quickly in those areas of the inner tank wall that are subject to high stress, especially towards the outlet. And the application of antistatic additives is limited, since they are effective only for a short time.

However, the preventive strategy attempts to start from the causes of electrostatic charges, which can be seen in the high inflow velocities of the liquid out of the valve. In order to reduce it, it is proposed to add a diffuser at the bottom end of the valve, which seals the aperture axially and has only radially directed openings so that the inflowing liquid is redirected. Thus, on the one hand it is decelerated and, on the other hand, does not impact the facing inner wall as a bundled jet, but is divided into several partial flows which, without further treatment, first diffuse in the horizontal direction and then, under the influence of gravity, impact the inner wall with a slight deviation, almost tangentially. However, in order to reduce the speed further, the patent proposes to additionally surround the diffuser in the outlet of the liner with a cylindrical collar, which is formed as part of the liner/hollow body. The liquid discharged from the radial opening of the diffuser thus strikes the collar and is thus redirected again and strongly decelerated.

The disadvantage of this solution is that due to the extreme deceleration of the liquid around the closing collar, the remaining space between diffuser and collar is filled, whereby a strong counterpressure is built up and the flow rate is thus greatly reduced. The flow in this space is very turbulent there, thus resulting in a heavy mechanical load of the adjacent components, diffuser, connection, boss and collar, which accelerates rapid aging.

However, a more serious problem of the strong back pressure in the space between diffuser and collar is the fact that it causes the inflowing liquid to be pressed into the joint between liner and boss, which is located on the upper side of the space between diffuser and collar, so that the tightness of the pressure groove may be threatened, especially at high filling pressures and rates.

Since the wall thickness and precision requirements of the boss are very different from the wall thickness and tolerance of the pressure groove, it is actually neither reasonable nor economical to manufacture the boss and groove in one piece.

Instead, it is customary that, after the hollow body has been completed, a separately produced and in most cases multi-part boss is provided in a further step. For example, patent application US 2011/010/1002 describes a plastic trough with two outlets. On each of the outlets, from the outside and from the inside, an approximately cylindrical boss is placed, which is widened at one end with a collar-like flange. The two parts are screwed together with a thread and are thus pressed together so that they are clearly located inside and outside the surrounding area of the outlet from the trough. The required pressure strength is obtained by a corresponding pressure and by a sealing ring additionally inserted in the trough or the flange.

Patent publication number US 2014/0299610 A1 describes a pressure groove with a two-piece boss, which consists of an outer part made of a softer and more flexible material, providing a connection to the hollow body/liner and its fiber reinforcement layer. A second part is concentrically embedded in the outer boss, which provides the possibility of connection to the valve or other connection parts in the form of internal threads. It is made of a harder material to withstand the forces generated. Between the inner part and the screwed valve is the sealing lip of the boss, which together with one or more sealing rings around the valve, fixes the valve in a tight position, even under high pressure.

This publication teaches to reduce the radial thickness of the sealing lip in proportion to the required test pressure. However, a disadvantage is that the sealing lip may not be able to counteract the deformation caused by the pressure of the valve, boss and outlet and especially the sealing ring under high pressure, which may lead to leakage.

In this context, the present invention has accomplished this task and developed a boss for composite pressure grooves that effectively prevents electrostatic charging but still achieves a high filling rate and guarantees absolute tightness under high pressure.

As a solution, the invention teaches to provide a static eliminator wall around the diffuser, which is formed as part of the boss or collar, which is described below, or as part of the connector. Tightness during filling is then ensured by the fact that the inevitable joint between the boss and the hollow body/liner is advantageously located outside the space between diffuser and static eliminator wall, which is stressed by high dynamic loads during filling.

In a preferred embodiment, this reduction in velocity pressure is achieved by means of a number of turbulence release openings spread out in its circumference. Liquid flowing into the space between the diffuser at the bottom of the pore and the static eliminator wall can leave the space through these openings. This can unload the remaining space between the diffuser and the static eliminator wall, thereby providing a higher flow rate. By properly positioning the turbulence release opening relative to the radial diffuser opening, the flow turbulence can be further influenced. It is therefore significant to provide at least one turbulence release opening in the static eliminator wall for each diffuser opening. It can be roughly aligned with the specified diffuser opening. In this case, a high flow rate can be achieved with minimal turbulence in the area of the boss. Ideally, the size of the turbulence relief opening is chosen to be slightly smaller than the jet cross-section of the liquid exiting the diffuser opening, taking into account the widening of the jet after leaving the diffuser opening. This results in the flow not being completely laminar, which reduces charge separation by the flow.

Another solution is to align the diffuser opening with the bulk of the wall section between the turbulence relief openings. Preferably, the diffuser openings are aligned with the middle of the wall sections in order to achieve as equal a load as possible on the wall sections, the load caused by the liquid hitting them with its dynamic force. By means of this relative positioning, a strong deceleration is achieved similar to the known prior art continuous circumferential collar, but with the essential advantage that, by means of the turbulence relief openings, the inflowing liquid has a further flow path and the greatest possible degree of stationary flow is generated in the space between them. Thus, the gravity stresses on the material from the high turbulence are eliminated and the static back pressure that occurs is advantageously significantly reduced. And in this embodiment, despite the deceleration and double redirection of the inflowing liquid, the maximum possible flow rate is hardly reduced compared to a tank without a diffuser (and/or static eliminator wall). By this alignment, the space between the outside and the inside creates a sprinkler like effect, in which the liquid, when it hits the wall segments of the static eliminator wall with full force, is finely dispersed into very fine droplets, which then partly fall directly downwards through the gap between the diffuser and the wall segments and partly diffuse finely out of the turbulent discharge opening into the outer tank volume. Thus, there are no longer bunched fluid jets that could cause further static charges when they hit the inner space of the hollow body.

The teaching of the invention has a further advantage when a material with better conductivity than the lining material is used for the boss, or when a non-conductive material is provided with a conductive coating. This is related to the fact that most of the charge carried away by the flow in the valve or the connection, i.e. the electrons, has already been deposited in the eliminator wall. This is also known in existing pressure tanks, however, an effective charge backflow is prevented by implementing a collar as part of the non-conductive hollow body. When the boss is made of conductive material, charge backflow is possible and problem-free in the present invention, since the eliminator wall is integrated in the boss.

The basic idea of the invention is therefore to integrate the smear wall into the boss of the pressure groove, which boss is ultimately used for a (pressure)-resistant connection of a practical connection piece and a hollow body including a possible fiber-reinforced cover layer, the practical connection piece is used to install a hose or tube containing a liquid. This prevents the joint between the boss and the hollow body from becoming a weak point in the space between the diffuser and the smear wall. Furthermore, the idea is further achieved by inserting turbulence relief openings in the course of a largely stationary less turbulent flow in the space between, which reduces the counter pressure built up and the stresses on the material of the component which is exposed to the pressure and correspondingly increases the flow rate for a given filling pressure. When the liquid hits a wall section of the static eliminator wall, or at the latest leaves the turbulence relief opening as a constriction, the liquid is dispersed like a sprinkler and leaves the region of the space between in a shower of fine and minimal droplets which no longer have sufficient kinetic energy to achieve a considerable charge handling when they could hit the inner wall of the hollow body or by friction in the air. Therefore, the anti-static effect of the static eliminator wall with turbulent release openings according to the present invention is at least equivalent to the anti-static effect of the static eliminator wall with a continuous collar, but avoids its huge disadvantages.

Further advantageous developments of the invention, which can be realized individually or in combination, insofar as they do not obviously exclude one another, are presented and described below.

2以及一鏡像對稱(mirror symmetry)。因此可以確保，藉由該流動和該扭矩之改向所產生之對凸台之負載是均衡的，並且總之凸台沒有負載和扭矩。 Preferably, the number of turbulence release openings is an integer multiple of the number of radial diffuser outlets. In particular, the present invention proposes to provide the same number of turbulence release openings and diffuser openings. In addition, it is preferred that the static eliminator wall has the same symmetry as the diffuser. It is particularly preferred that the diffuser and the static eliminator wall including the turbulence release openings have n-fold rotational symmetry, where n

2 and a mirror symmetry. It is thus ensured that the loads on the bosses caused by the redirection of the flow and the torque are balanced and that overall there is no load or torque on the bosses.

The turbulence release openings can have different forms, for example circular or elliptical openings in the static eliminator wall. However, preferably, they are designed as elongated gaps or grooves, starting from the bottom edge of the static eliminator wall and extending over a substantial part of its vertical dimension, having a width in the tangential direction that corresponds approximately to the diameter of the diffuser opening. Firstly, they are easy to manufacture and secondly result in a flow direction of the inflowing liquid in the boss area that represents a very good balance between turbulence and laminarity and together is a quasi-static flow. For further flow control, the side profile of the static eliminator wall can be varied, for example, additional corrugations can be applied to the basic circular profile or a polygonal basic shape can be chosen.

Another possibility to favorably influence the flow conditions during the filling of the pressure tank is to apply a suitable topography on the front surface of the diffuser, onto which the inflowing liquid impinges before leaving the diffuser opening. This can be designed, for example, as a projection or conical elevation opposite to the flow direction of the impinging liquid, which leads to improved pressure relief of the boss and higher flow rates.

In order to be able to ensure overpressure protection during the release of liquid from the pressure tank, for example in the event of a pipeline rupture, a mechanism can be integrated in the diffuser which closes the pores at excessive flow rates.

Another advantageous embodiment is to design the eliminator wall as a separate component to be fixed to the connector. This simplifies the maintenance and replacement of the eliminator wall, since it is a frequently used and easily worn component. When using an eliminator wall without turbulence release openings, which is subject to the highest loads when the liquid hits it, this ease of maintenance constitutes a significant advantage over prior art designs, in which the appropriate collar is an internal integral part of the hollow body/liner.

Regardless of whether the sapphire wall is fixed to the connection or is designed as an integral part of a boss or collar, it can be made of different materials in order to influence the electrostatic or wear properties. Thus, for example, thermoplastic materials can also be used in addition to metals.

The boss of the pressure groove according to the invention is in the most common case made of a single piece, i.e. the connection or connection possibility of a valve, hose, tube or the like is integrated in the boss itself. This advantageously avoids individual joints at additional contact points, which could jeopardize the tightness of the pressure groove. Due to the different requirements on the material properties of the boss in the contact area with the hollow body, which must have sufficient flexibility and elasticity to correspond to the elongation of the hollow body under pressure load and thermal influence, and in the area of the connection with the valve, hose or tube containing the liquid, it requires sufficient stability and hardness to avoid rapid fatigue during frequent connection and disconnection, however, the present invention proposes at least a two-piece embodiment of the boss. In this case, a second component, the so-called collar, made of a hard material, preferably metal, is concentrically embedded in an external connection made of a softer, more resistant material, in particular a material similar to the thermoplastic material of the hollow body, which can be connected by liquefaction. Such a collar has an internal thread or another connection possibility for connection to a valve or another connection. The collar is thus pressed or molded into a complementary opening of the actual boss. Alternatively, the boss is formed by a casting or injection process around the collar.

The collar, in particular its contact area with the actual boss, preferably has no circular symmetry, but only an n-fold rotation or particularly preferably a mirror symmetry of a mirror plane, which includes the axial direction. The shape of the contact area can be, for example, a polygon, a star or a waved line. As a result, the contact area is increased and the torque can be better transmitted from the collar to the boss. In addition, the invention proposes to insert circumferentially extending grooves and/or connecting holes in the collar or flange respectively surrounding the collar, into which liquid thermoplastic material can flow during the manufacturing process. After cooling, a particularly stable connection suitable for torque transmission is thus achieved. This is important because the torque that can occur during possible frequent replacements, i.e., squeezing a connection in and out, can degrade the engagement between the collar and the actual boss, which can lead to leakage over time and eventually failure of the boss.

The same applies to the a.m. torque transmission from the boss to the hollow body. The contact area between the boss and the hollow body is therefore also formed as a non-circular torque coupling. As in the contact area from the collar to the boss, the shape here can also be polygonal, star-shaped or wavy. Alternatively, a thermoplastic hollow body can be blow-molded around the boss, which ensures a very tight connection and force transmission, especially when the outer area of the boss has vertical holes, into which the still liquid material of the hollow body can flow and solidify there. The disadvantage in this case is that the boss is already available when the hollow body is manufactured and cannot be replaced without damaging the boss.

The invention therefore preferably proposes that contact areas for the boss or bosses are designed in the region of the outlet of the hollow body so that they are accessible from the outside, so that the bosses can be inserted and welded and/or impressed after the hollow body has been prepared and solidified. In particular, the axial cross-section of the outlet should increase exactly outwards so that the axial projections of the cross-section located on the further outer side include those on the further inner side. If the boss part is made of a thermoplastic material similar to the material of the hollow body, the connection is preferably made by liquefying the surfaces of the contact area and pressing them together.

In the prior art, diffusers are connectors, i.e. valves for connecting hoses or pipes, and in the most general case, the present invention also includes such embodiments. Preferably, however, the present invention proposes integrating the diffuser, for example the static eliminator wall, into the boss itself. This is in contrast to the background art, in which a connector is usually an internal thread or a collar screwed to the boss, and the connector does not always have the same angular position relative to the static eliminator wall, but rather changes the position at least slightly with each tightening process. Therefore, the relative position of the diffuser opening to the turbulence release opening is also not always the same, which may have a negative effect on the flow process of the inflowing liquid. By integrating the diffuser into the boss, this relative position variation is advantageously eliminated.

The radially guided diffuser opening is preferably circular, elliptical or polygonal, especially rectangular.

Another advantage of this embodiment is that standard connectors are not usually equipped with diffusers, but rather have a simple axially guided inlet at the bottom end. By integrating the diffuser into the boss itself, the present invention can therefore take advantage of the deceleration of liquid flowing through the diffuser and antistatic smear wall at high pressure, while using a standard connector.

The collar, which is embedded in the actual boss, preferably has a certain center groove at the top of its outlet. This ensures that during the manufacturing process of the boss, the collar and the boss are always positioned constantly, which is important for the relative alignment of the turbulence relief opening and the diffuser opening. This also simplifies the rapid connection and centering of the subsequent connection, especially when this should be done in an automated manner, for example by an assembly robot.

In a further preferred embodiment, the neck ring comprises a collar which is guided axially downwards and is surrounded on its outer side by the material of the boss. On the one hand, the contact area with the actual boss is thus further enlarged. On the other hand, the material of the boss guided radially inwards from the collar forms a sealing lip whose radial thickness has a significant influence on the tightness of the pressure groove.

Due to the limited vertical dimension of the boss, the aperture extends slightly into the interior of the hollow body when the boss is installed. The pressure in the groove now affects the toroidal protrusion both inside and outside, so that the inner side is formed by the base of the connection piece or the boss, either without or with an integrated diffuser, depending on the design. As a result, the material of the boss and in particular the material of the sealing lip is compressed. Furthermore, the pressure in the groove presses the liquid or gas into the gap between the sealing ring and the sealing lip of the connection piece, and the sealing ring and the sealing lip are deformed to such an extent that the forces between the tension of the sealing ring, the sealing lip and the pressure in the groove are balanced out.

In the case of an underdimensioning of the chosen radial thickness of the sealing lip, this leads to leakage in the connection between the actual boss and the collar or between the boss and the connection. The latter can be avoided by using a sealing ring between the connection and the sealing lip. The hardness of this sealing ring should increase with the test pressure of the groove and therefore also with the desired maximum filling pressure.

Therefore, the present invention proposes a radial thickness of the sealing lip of larger size, which has the desired test pressure of the groove of the embodiment. In practice, it is recommended to increase the thickness of the sealing lip in proportion to the test pressure. Tests provide evidence that the best tightness is guaranteed according to the change of the relationship Dmax (mm) = 0.01P (bar) + 3.0 Dmin (mm) = 0.019 Dmax (mm) + 2,95. P is the test pressure, the lower limit of the preferred radial sealing lip thickness D is Dmin, and the upper limit is Dmax. The sealing ring used between the sealing lip and the connection is estimated to have a shore hardness of at least 90.

An alternative to the prior art, which is particularly suitable for sealing between bosses and valves of pressure grooves with hollow bodies made of steel, is the use of valves with conically tapered external threads. The metal seal achieved here is still supported by a viscous sealant in standard practice, making it unnecessary to use sealing rings. In an advantageous embodiment of the invention, the connection of such a tapered valve is provided by a suitable neck ring design. In particular, the design of bosses without diffusers is solved, since tapered valves in the most widely distributed design are already equipped with diffusers, but without static eliminator walls. In order to be able to adjust the relative position of the diffuser opening and the turbulence release opening also in this embodiment, it is recommended to provide suitable markings on the boss and the valve, which indicate the position of the opening.

In order to withstand very high test pressures of several hundred to more than one thousand bar, the hollow body of the pressure tank of the invention must have an outer fiber-reinforced covering layer. This is all the more necessary because the thermoplastic material proposed for the hollow body can only withstand a few bars, at least about 10 bars, with a typical wall thickness in the range of a few millimeters. The fibers used in this layer can be synthetic fibers, such as glass, carbon, aramide, Dyneema or other synthetic fibers, or natural fibers. Different types of fibers can also be processed in combination to optimize costs, for example in the case of requirements for rigidity. The matrix in which the fibers are embedded consists of a heat-curing or UV-curing (synthetic) resin, such as epoxy, or a plastic, such as polyethylene, which can be applied to the fiber-wrapped liner in liquefied form and then allowed to solidify. It is particularly preferred that the hollow body surface is treated before being wrapped with fibers and applying the matrix in which they are embedded, which increases the roughness and thus achieves better adhesion between the composite layer and the liner/hollow body.

1: Hollow body

11: Exit in the hollow body 1

111: Exit contact area

12: Joint between the hollow body and the boss

13: The interior of the hollow body

2: Boss

20: Boss part

21: Porosity

22: Diffuser

221: Diffuser opening

222: Inner front surface of the diffuser with protrusions

23: Necklace

231: Neck ring

232: Neck ring flange

233: Neck ring hole

234: Centering groove

24: Sealing lip

25: Internal thread

26: Boss contact area

27: Static eliminator wall

271: Internal static eliminator wall surface

28: Turbulence release opening

3: Connectors

31: Sealing ring

8: Fiber reinforcement layer

81: Torque coupling

9: Pressure release device

P: Test pressure

D: Sealing lip thickness, radial

Dmin: minimum recommended sealing lip thickness

Dmax: Maximum recommended sealing lip thickness

TP: Pitch

HT: thread height

DO: Distance from sealing ring to bottom thread edge

The following is an embodiment of the diagram to further illustrate the specific details and features of the present invention. However, this should not limit the present invention, but only explain the present invention.

Shown in the schematic:

Figure 1: Cross section of an embodiment of the pressure trough of the present invention having a static eliminator wall with turbulence release openings on the boss and an integrated diffuser with a connector.

Figure 1a: Enlarged portion of the bottom of the boss in Figure 1.

Figure 2: A perspective view of the boss from below in Figure 1.

Figure 3: Another embodiment of a boss with an integrated diffuser, perspective and cross-sectional views from below.

Figure 4: Relationship between test pressure and radial sealing lip thickness.

Figure 5: Cross section of another embodiment of a boss having a contoured diffuser front surface.

Figure 6: Cross section of another embodiment of the boss and the connector, where the static eliminator wall belongs to the latter and the diffuser.

Figure 7: A perspective view from below of another embodiment of a connector having a static eliminator wall and a diffuser.

Figure 8: Cross section of another embodiment of a boss with an integrated pressure relief device in a diffuser (closed position).

Figure 8a: Cross section of the boss of Figure 8 with the pressure release device opened.

FIG. 1 shows a cross section of the outlet of the pressure groove according to the present invention with a mounting boss. The boss 2 is tightly connected to the outlet 11, so that the complementary boss contact area 26 and the outlet contact area 111 form a torque coupling for constant and effective transmission of torque from the boss 2 to the hollow body 1. Another torque coupling is formed by the contact area between the boss portion 20 of the boss 2 and the fiber reinforcement layer 8, which covers the hollow body 1 and part of the boss portion 20. The boss 2 has two parts and is composed of an outer boss portion 20 and its integrated neck ring 23, which has an inner thread 25 for screwing the connector 3 into the boss 2. During the manufacturing process, especially in an automatic manner by an assembly robot, the centering groove 234 at the upper end of the internal thread 25 is used to facilitate the operation and positioning of the connector 3. At the bottom end of the hole 21, the diffuser 22 is an integral part of the connector 3.

The diffuser 22 is used for deceleration and redirection of a liquid flowing under high pressure by means of a pore 21 closed in the axial direction and comprises only a radial opening 221. After passing through the diffuser opening 221, the radially flowing liquid hits the static eliminator wall 27 around the diffuser 22 at a lower speed than the theoretical flow velocity without the diffuser, and this static eliminator wall is formed as a cylindrical collar interrupted by a turbulent release opening 28, which is designed as an elongated groove. The static eliminator wall 27 is an overhang of the outer boss portion 20 in the axial direction and is therefore an integral part of the boss portion 20. In this embodiment, the diffuser 2 has a mirrored and rotationally symmetrical design with 6-fold rotational symmetry, so that during the filling process, the connection remains force- and torque-free. The same applies to the static eliminator wall 27.

This ensures the necessary improvement of the invention, in particular the joint 12 between the hollow body 1 and the boss 2, which is located outside the space between the diffuser 22 and the static eliminator wall 27. It is thus advantageously avoided that the liquid flowing in at high pressure is pressed into the joint due to the high static back pressure that is established between the said spaces, possibly together with the dynamic pressure of the liquid, which hits the boundary surfaces of the space therebetween at high pressure, thus permanently damaging the tightness of the pressure groove during the filling process or in the worst case during plastic deformation.

This is facilitated by the fact that only a small back pressure is built up in the space, since the turbulence relief opening 28 creates an additional outflow path. When flowing through the opening 28, the liquid is thus dispersed into a "mist" of fine droplets, which minimizes the risk of electrostatic charging of areas further away from the outlet 11.

During the filling process and in the pressure filling state, the tightness of the pressure groove of the invention is further ensured by the size of the radial thickness of the sealing lip 24, which is located between the neck ring collar 231 and the sealing ring 31 of the connecting part 3, and the neck ring collar 231 extends downward from the neck ring 23 in the radial direction.

0.5 TP之關係，選擇內螺紋25之高度HT與內螺紋25之底部邊緣和O形環31之間之距離DO之差值，TP代表內螺紋25之螺距。 Figure 1a shows an enlarged cross section of the lower half of the boss 2 at the bottom end of the aperture 21.

The difference between the height HT of the internal thread 25 and the distance DO between the bottom edge of the internal thread 25 and the O-ring 31 is selected based on the relationship of 0.5 TP, and TP represents the pitch of the internal thread 25.

FIG. 2 shows a perspective view from below onto the boss of FIG. 1. It shows a hexagonal boss contact area 26 forming a torque coupling for transmitting torque from the boss 2 to the hollow body of the pressure groove, having a complementary contact area of the outlet of the hollow body in which the boss 2 is mounted and welded or glued. The connector 3 is squeezed onto the internal thread of the invisible neck ring 23, and the connector 3 includes a diffuser 22 at its bottom end, which diffuser 22 forms a flow obstacle in the axial direction. The connector 3 is tightened to such an extent that the diffuser opening 221 extending in the radial direction is approximately aligned with the turbulence release opening 28 in the static eliminator wall 27. Thus, a high flow rate is achieved during filling, but at the same time a suitable antistatic effect is also achieved by the appropriately narrow dimensioning of the turbulence release opening 28 in width. However, this effect is optimized when the diffuser opening 221 is not aligned with the turbulence release opening 28, but faces those continuous static eliminator walls 27, so that the liquid flowing out of the opening 221 hits these and is further slowed down. In this case, almost all loads carried away from the connection 3 or the diffuser 22 are deposited in the eliminator wall 27, from where they are guided by droplets to the connection 3, respectively the diffuser 22, since the eliminator wall 27 is part of the boss 2, which can be designed to be relatively more conductive, than the non-conductive hollow body 1.

In FIG. 3, another preferred embodiment of the boss of the pressure groove of the present invention is shown. The upper part of the figure shows a perspective view from a lower angle, indicating that the diffuser opening 221 is aligned with the turbulence release opening 28 relative to the static eliminator wall 27, in such a way that the fluid jet flows out of the opening 221 and accurately hits a large block of the static eliminator wall section 27. Similar to the embodiment shown in FIGS. 1 to 2, the diffuser 22 also has a mirror image and a 6-numbered rotation symmetry.

The lower part of the figure shows a cross-sectional view of the boss 2. It can be seen that it is also formed of two parts, namely the outer boss portion 20 and the neck ring 23. The neck ring 23 then includes an internal thread 25, which is used to mount a hose, tube, valve or other connection. The essential difference from the previous embodiment is that the diffuser 22 clearly visible in the cross-sectional view forms an integral part of the boss 2, in particular the boss portion 20. It thus avoids the relative alignment of the diffuser opening 221 with the static eliminator wall 27 and the turbulence release opening 28, which may vary with each screwing process.

FIG. 4 shows the relationship between the radial thickness D of the sealing lip 24 recommended by the present invention and the required test pressure in a curve diagram. The sealing lip thickness is shown on the y-axis and the pressure is shown on the x-axis. At the maximum recommended thickness Dmax, the course increases exactly in a straight line with a proportional constant (slope) of 0.01 mm/bar, and at the minimum recommended thickness Dmin, the proportional constant (slope) is 0.019 mm/bar. At the axis intercept at 100 bar, the minimum and maximum recommended thicknesses are 3.03 mm and 4.0 mm, respectively. Therefore, the radial thickness D for the specified test pressure P should be between Dmin and Dmax to ensure the best tightness.

FIG. 5 shows another advantageous embodiment of the boss 2 of the pressure groove of the present invention, which has a truncated cone-shaped protrusion on the inner front surface 222 of the diffuser facing the flow direction of the inflowing liquid for modifying the flow conditions. The lateral neck ring flange 232 stabilizes the neck ring 23 for axial loading. The neck ring hole 233 is inserted into it, and the liquid thermoplastic material of the boss can flow into it during the manufacturing process.

FIG. 6 shows an embodiment in which the diffuser 22 and the static eliminator wall 27 form part of the connector 3. This provides the particular advantage that the static eliminator wall 27, which is a high stress component, can be easily repaired or replaced by disassembling the connector 3.

FIG. 7 shows an embodiment of a static eliminator wall 27 and a diffuser 22, wherein the turbulence release opening 28 of the static eliminator wall is gradually narrowed radially and shows a polygonal profile. Such shaping of the turbulence release opening and the appropriate profile on the inner surface of the static eliminator wall facing the diffuser 22 indicate that it is possible to clearly guide the liquid flow and also affect the material wear of the static eliminator wall 27 itself.

FIG. 8 shows an embodiment of a diffuser 22 with an integrated pressure relief device 9, which is shown here in the closed position. FIG. 8a shows a supplementary illustration of the pressure relief device 9 in the open position. In the event of a sudden loss of pressure on the outlet side, and thus an increase in flow during liquid unloading, such as when a pipeline bursts, the pressure relief device is pulled and closes the outlet above the diffuser opening 221.

1: Hollow body

11: Exit in the hollow body 1

111: Exit contact area

12: Joint between the hollow body and the boss

13: The interior of the hollow body

2: Boss

20: Boss part

21: Porosity

22: Diffuser

221: Diffuser opening

23: Necklace

231: Neck ring

234: Centering groove

24: Sealing lip

25: Internal thread

26: Boss contact area

27: Static eliminator wall

28: Turbulence release opening

3: Connectors

31: Sealing ring

8: Fiber reinforcement layer

81: Torque coupling

Claims (17)

A pressure tank for storing high-pressure and low-pressure liquids/gases including liquefied petroleum gas (LPG), liquefied natural gas (LNG) or compressed natural gas (CNG), the pressure tank comprising: - a hollow body (1) of thermoplastic material having at least one outlet (11) with a surrounding outlet contact area (111), - Each outlet (11) has a boss (2), the boss (2) having at least one aperture (21) leading to the interior (13) of the hollow body (1), and the boss (2) having a complementary boss contact area (26), the boss being connected to the outlet contact area (111) of the hollow body (1) by the boss contact area (26), whereby the outlet contact area (111) and the boss contact area (26) form a first torque coupling , the aperture (21) has a diffuser (22) at a bottom end, which may be part of the boss (2), or part of a neck ring (23) or part of a connector (3) for coupling to a fluid feed line, the connector (3) being connected to the boss (2) by means of the neck ring (23), and the diffuser seals the aperture (21) in the axial direction and has a plurality of diffuser openings (221) pointing mainly in the radial direction, - An electrostatic eliminator wall (27) inside the hollow body (1) surrounds the diffuser (22), and is characterized in that the electrostatic eliminator wall (27) is an integral part of the boss (2) or a part of the neck ring (23), or is fixed to the connector (3) as a separate component. According to the pressure tank described in item 1 of the patent application, the feature is that the static eliminator wall (27) has a plurality of turbulence release openings (28) which are positioned relative to the diffuser opening (221) so that the liquid flowing in under pressure generates a mainly static flow in the area below the boss (2). According to the pressure tank described in item 2 of the patent application, the turbulence release opening (28) is a thin and long opening starting from the bottom edge of the static eliminator wall (27), and/or is aligned with the diffuser opening (221) of the diffuser (22), or is aligned with the segments of the static eliminator wall (27), which are separated from each other by the thin and long opening starting from the bottom edge of the static eliminator wall (27) and extending to the top edge of the static eliminator wall (27). The pressure groove according to any one of items 1 to 3 of the patent application scope is characterized in that the static eliminator wall (27) has a circular profile or a more complex profile, and the more complex profile is selected from a wavy line profile or a polygonal profile along the surface (271) of the static eliminator wall facing the diffuser (22). The pressure tank according to any one of items 1 to 3 of the patent application scope is characterized in that the diffuser (22) - has a diffuser opening (221) of circular, elliptical or polygonal shape, or - has an inner front surface (222) which is flat or has a more complex surface morphology, the more complex surface morphology being selected from a convex surface or a conical protrusion; or - has a mechanism (9) that closes the pore (21) during a critical flow rate of the liquid. The pressure groove according to any one of items 1 to 3 of the patent application scope is characterized in that the hole (21) of the boss (2) has an internal thread (25), the connecting member (3) is inserted into the internal thread (25), and has at least one sealing ring (31) for sealing purposes, or a tapered external thread. According to the pressure groove described in item 6 of the patent application, the boss (2) includes an injected or embedded neck ring (23) which is concentrically located at an outer connecting portion (20) of the boss (2) and provides the hole (21) and at least a part of the internal thread (25). According to the pressure groove described in item 7 of the patent application, the characteristics are that the neck ring (23) - has a reduced symmetry relative to the rotation in the axial direction around the hole (21) compared with circular symmetry, and/or - has a mirror symmetry of a mirror plane, which includes the axial direction, and/or - has a surrounding collar (232), extending in the radial direction, having a hole (233) therein, and/or - has a centering groove (234) at the top of the hole (21), and/or - is made of metal, and/or - has connected holes and grooves. According to the pressure groove described in item 7 of the patent application, the feature is that the external connection part (20) is made of a thermoplastic material and includes the boss contact area (26), and the external connection part is connected to the outlet contact area (111) of the outlet (11) in the hollow body (1) through the boss contact area (26) through injection, bonding or welding of the surface liquefaction of the thermoplastic material of the outlet contact area (111) and the boss contact area (26) and subsequent compression. According to the pressure groove described in item 7 of the patent application, the feature is that the neck ring (23) has a downward neck ring collar (231) surrounding the hole (21) on the bottom side, and the collar is embedded outside the material of the external connection part (20), so that the inner side of the neck ring collar (231) and the boss (2) material between the hole (21) form a sealing lip (24). According to the pressure groove described in item 10 of the patent application, it is characterized in that at least one sealing ring (31) is located between the connecting part (3) and the sealing lip (24). According to the pressure groove described in item 10 of the patent application, the characteristic is that a radial thickness of the sealing lip (24) is selected in proportion to a test pressure of the pressure groove (1). According to the pressure groove described in item 10 of the patent application, the radial thickness of the sealing lip (24) is selected to be between a minimum thickness (Dmin) and a maximum thickness (Dmax), and the thicknesses are related to the test pressure (P) by the following relationship: Dmax (mm) = 0.01P (bar) + 3.0 Dmin (mm) = 0.019 Dmax (mm) + 2.95. The pressure groove according to any one of items 1 to 3 of the patent application scope is characterized in that the first torque coupling is used to transfer torque from the boss (2) to the outlet contact area (111) and the boss contact area (26) on the hollow body (1), and has an n-fold rotational symmetry. A pressure tank according to any one of claims 1 to 3, characterized in that a fiber reinforcement layer (8) is wound around the hollow body (1), the fiber reinforcement layer being reinforced by fibers selected from glass fibers, carbon fibers, aramid fibers, dyneema fibers, other synthetic fibers and/or natural fibers, and further comprising a matrix in which the fibers are embedded, consisting of a heat or UV-curable resin or other resin, and before the application of the reinforcement layer, the surface of the hollow body (1) is subjected to a further treatment for achieving a better bond between the fiber reinforcement layer and the hollow body. According to the pressure groove described in item 15 of the patent application, it is characterized in that a second torque coupling (81) is integrally formed in the fiber reinforcement layer (8) in the outlet (11) area, and the second torque coupling has a non-circular symmetrical shape. According to the pressure groove described in item 6 of the patent application, the difference between the height (HT) of the internal thread (25) and the axial distance (DO) between one bottom end of the internal thread (25) and the center of the sealing ring (31) complies with HT (mm)-DO (mm).

The relationship of 0.5TP and the height (HT) of the internal thread (25) complies with the relationship of HT (mm) = _nT TP (mm), (TP) is the pitch of the internal thread (25) in millimeters per winding, and _nT refers to the number of windings of the internal thread (25).

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