EP1391571B1 - Elongated roller-type shutter profile made of plastic or metal for swimming pool covers - Google Patents

Abstract

The shutter profile (1) has a sealing body (13a, 13b) made of an elastic material, which based on a mounting state in which the sealing body is inserted into a hollow chamber (3a, 3b). The sealing body is brought into a sealing state by clamping between piston plate (12a, 12b) and a cap (11) in which the sealing body is expanded in a direction perpendicular to a longitudinal direction (2) of the chamber.

Description

The invention relates to an elongated shutter profile made of plastic or metal for Swimming pool covers, with at least one watertight closure, with which at least a in the longitudinal direction of the shutter profile extending hollow chamber at a End of the shutter profile is closable, wherein the closure of a cap, by the End face from at least partially inserted into the hollow chamber, one at a distance from the Cap has within the respective hollow chamber arranged piston plate and a Having between the cap and the piston plate extending sealant.

Such a shutter profile is for example from EP 0 225 862 A1 and EP 0 732 469 A1 known. The known shutter profiles are in particular in the form of extruded Plastic profiles used for swimming pool covers. Because the pool covers resting on the water surface and due to the air-filled hollow chambers Floating the water surface, it is important to the shutter profiles at their ends complete watertight. Due to the use of such shutter profiles outdoors particular care should be taken that both the material of the shutter profile itself, but also the materials of the closure are weather resistant, i. especially resistant to UV radiation and larger temperature fluctuations are. In no case may the materials during the lifetime of such covers embrittle or as a result of Discard temperature fluctuations, which in turn could occur leaks.

In the shutter profiles known from EP 0 225 862 A1 and EP 0 732 469 A1 the piston plates each connected via a piston rod-like shaft with the cap. The cap has a plug portion which corresponds to the cross section of the respective hollow chamber adapted and introduced in these. The cross section of the piston plate is also adapted to the cross section of the hollow chamber. The production of the tightness happens in that each of the located between the piston plate and the plug portion Interspace completely filled with an initially flowable sealant is through an opening in the plug portion of the cap from the outside by means of a suitable filling device is introduced. This is based on a plastic material On the one hand, sealant has certain adhesive properties that create a lasting bond the same effect with the walls of the hollow chamber, and cures on the other hand after a certain time out. In this way, a permanent non-reversible closure the shutter profile are achieved. While in the known from EP 0 225 862 A1 Roller shutter profiles of each hollow chamber have their own supply opening and one next to it Assigned vent or overflow is assigned, which consists of EP 0 732 469 A1 known development in that adjacent hollow chambers in the way of a known development in that adjacent hollow chambers in the way of a single Filling process can be closed. For this purpose, the liquid sealant flows first through a feed opening into the first hollow chamber, then through an overflow channel in the cap in the adjacent hollow chamber and from there in possibly further adjacent Hollow chambers penetrate. In the last of such series connected hollow chambers There is a vent or overflow in the associated plug portion the cap, so that the filling process can then be stopped when out of this Opening leakage sealant.

Although with the further development described in EP 0 732 469 B1 a reduction the working time in the production of such waterproof closures can be achieved could, is the use of such flowable and curing sealants in general problematic. For example, one disadvantage is that the closures are not instantaneous can be mechanically stressed after filling with the sealant since this only after a certain time reaches the necessary hardness, i. a possible force can resist. In addition, the filling of the sealant in the space between piston plate and cap only with a certain delivery rate take place, so that in practice a time required per filled hollow chamber of several Seconds arises. Another disadvantage is that interruptions of Befiillvorgangs cause hardening of the sealant also in the filling device, so that before resuming filling time-consuming cleaning work required are.

The invention has for its object to provide a closure for a shutter profile for To develop swimming pool covers so on, on the one hand, the time required in the Producing the tight closure reduced and on the other hand if possible a Wiederaufhebbarkeit the seal is made possible.

Based on the shutter profile of the type described above, this object is achieved according to the invention achieved in that the sealing means is a sealing body made of an elastic and / or plastic material, starting from a mounting state in which he in the hollow chamber is inserted, by clamping between the piston plate and the Cap is convertible to a sealing state in which it is in the direction perpendicular to the longitudinal direction the hollow chamber is extended so that it is circumferentially close to the hollow chamber abuts limiting walls.

The closure according to the invention thus initially differs from the prior art Technique that no longer a flowable sealant is used, but a sealing body, Although the elastic and / or plastic properties, but basically without external force is essentially dimensionally stable. The sealing effect against the Walls of the hollow chamber is achieved according to the invention in that on the sealing body pressure is exerted on both sides in the direction of the longitudinal direction of the hollow chamber, so that as a result, a deformation occurs, which increases the size causes the sealing body in the direction perpendicular to the longitudinal direction of the hollow chamber. These Expansion of the shutter profile causes a circumferential system of the same on the walls the hollow chamber, so that the desired sealing effect occurs.

Advantageously, therefore, the use of a sealant is no longer required, its properties after filling in between the piston plate and the cap located intermediate space changed in such a way that it is flowable from first in sufficiently fixed changes. A chemical or whatever material change after the placement of the shutter profile with the closure is according to the invention Teaching no longer required. Aging problems, as with a too long storage of liquid sealants of the prior art under certain circumstances can occur, are therefore not to be feared according to the invention. Also allows the invention when using suitable materials a reversibility of the closure in the Meaning that after a release of the tension of the sealing body between the piston plate and the closure cap due to a recovery of the sealing body a detachment enters from the walls of the shutter profile, so that the shutter in total again can be removed. When using a substantially exclusively plastic deforming sealing body, which may still be in connection with the Hohlkammerwandungen Possesses adhesion properties, is the property of reversibility Of course, not given, as a recovery and detachment of the sealing body of the walls in this case is hardly achievable.

In principle, it is conceivable that the piston plate on a projection on the walls the hollow chamber rests, the further displacement of the same in the interior of the hollow chamber prevents, and a tension between the piston plate and the cap thereby is achieved that the cap also engages behind a projection, for example. Of the Distance between piston plate and cap in this sealing state of the closure is so dimensioned that thereby adjusting shortening of the sealing body in the axial direction sufficient radial expansion of the same causes an investment on the walls to achieve with sufficient preload.

According to a particularly preferred embodiment of the invention, it is provided that a Connecting element is present, which extends between the cap and the piston plate and at least in the transfer of the sealing body in the sealing state under tension stands. In this case, a support of both the piston plate and the cap on the walls of the shutter profile is not required, which is especially true for extruded Profiles is advantageous because such projections, i. Abutment, not easy to generate. It may be sufficient to check the tension on the connector, i.e. the compressive stress on the sealing body only once or for a certain Period to produce, namely, when the sealing body made of a plastic material exists, which develops a strong bond in conjunction with the walls of the hollow chamber. In this case, even after a release of the tension on the connecting element, i.e. a pressure relief of the sealing body, due to the weak or not pronounced elasticity properties not calculated with a reversion of the sealing body so that the circumferential adhesion to the walls also without further Force on the sealing body is maintained.

In the case of shutter profiles with several mutually parallel hollow chambers each separated by a running in the longitudinal direction of the shutter profile partition are separated, the sealing process is done in a particularly rational manner if the closure has a cap which can be introduced into several hollow chambers at the same time is and one of the number of hollow chambers corresponding number of Dichtkörpem and piston plates is assigned.

According to a further embodiment of the shutter profile according to the invention penetrates the Connecting element, the sealing body and the cap and is in the longitudinal direction of the hollow chamber movable relative to the sealing body and the cap. The penetration of the sealing body allows a reliable seal on its periphery, i. especially an immediate one Plant of the elastic or plastic material of the sealing body to the surrounding Chamber walls.

A development of the invention also consists in that the connecting element a Screw is, whose thread cooperates with the piston plate. Preferably permeates the screw also the cap and is supported on the outside with her screw head. In the piston plate can, for example, by means of their injection molding production A metallic nut is molded with the machine thread of the screw interacts. Alternatively, it is also possible, only a blind hole in the Mold in the piston plate into which a self-tapping screw is screwed becomes.

An alternative embodiment of the shutter profile according to the invention is that the rod-shaped connecting element is integrally connected to the piston plate and on its surface is barbed, which cooperate with a pawl, which is arranged in the cap. In this working on the principle of cable ties Connection between piston plate and cap is the process of production the bias on the sealing body greatly simplified. A free and protruding from the cap End of the connecting element must only with a defined force in the direction be pulled out of the hollow chamber. The bias on the sealing body remains after canceling the external traction by the blocking function of the barbs permanently preserved. A reversible cancellation of the sealing effect is in this closure principle but not possible. Basically, however, is an unlocking option for Pawl conceivable.

Furthermore, a further development of the shuttering profile according to the invention is that the Piston plate and / or the cap at its the sealing body facing frontal contact surface conically raised and the sealing body itself on at least one of its two opposite to the contact surfaces of the piston plate and / or the cap corresponding frontal contact surfaces is complementary conical sunken. The interaction the conical surface with the complementary cone surface leads the axial tension of the cap and the sealing body or of the piston plate and sealing body to an improved implementation of the axial stress in a radially directed expansion of the sealing body. The complementary conical / conical contact surfaces can either attached only on one side to the sealing body and the respective adjacent component be or on both sides of the sealing body.

In addition, it is still possible, the sealing body with an annular self-contained and to provide externally closed cavity with a gas filling. At an axial Compression of the sealing body between the piston plate and the cap performs the compression the cavity due to its tightness to a radial expansion of the same. In Connection with the reduced wall thickness of the sealing body in the area between the Cavity and the wall of the hollow chamber of the shutter profile is an improved nestling causes the outer shell of the sealing body to the inner shell of the hollow chamber.

Finally, it is also within the scope of the present invention, a closure for waterproof Closing an elongated shutter profile made of plastic or metal to provide the closure, the features and properties described above having. Such closures can be, for example, as spare parts for already use existing shutter profiles or market them as independently tradable goods.

Figur 1:

eine Draufsicht auf einen Verschluss eines abschnittsweise dargestellten geschnittenen Rolladenprofils;

Figur 2:

eine Seitenansicht des Verschlusses gemäß Figur 1;

Figur 3:

eine Rückansicht des Verschlusses nach Figur 1;

Figur 4:

eine Vorderansicht des Verschlusses nach Figur 1;

Figur 5:

einen alternativen Verschluss mit Verbindungselementen in Form von Maschinenschrauben;

Figur 6:

einen weiteren alternativen Verschluss mit Verbindungselementen in Form von Schrauben mit selbstschneidenden Gewinden;

Figur 7:

einen weiteren alternativen Verschluss mit kegel-/konusförmige Kontaktflächen zwischen Dichtkörper und Kolbenplatte sowie Dichtkörper und Kappe und

Figur 8:

einen weiteren alternativen Verschluss mit einem Dichtkörper mit einem ringförmigen Hohlraum.

The shutter according to the invention of a shutter profile will be explained in more detail below with reference to several embodiments, which are illustrated in the drawing, in which:

FIG. 1:

a plan view of a closure of a sectionally cut cut shutter profile;

FIG. 2:

a side view of the closure of Figure 1;

FIG. 3:

a rear view of the closure of Figure 1;

FIG. 4:

a front view of the closure of Figure 1;

FIG. 5:

an alternative closure with fasteners in the form of machine screws;

FIG. 6:

a further alternative closure with fasteners in the form of screws with self-tapping threads;

FIG. 7:

a further alternative closure with conical / conical contact surfaces between the sealing body and the piston plate and sealing body and cap and

FIG. 8:

a further alternative closure with a sealing body with an annular cavity.

A in Figures 1 to 4 sections in a longitudinal section shown shutter profile 1, consists of a thermoplastic material (for example, PVC) and is in Ways of extrusion made. The shutter profile has two in the longitudinal direction 2 extending hollow chambers 3 a and 3 b, of two longitudinal walls 4 and 5 and a be limited between the hollow chambers 3a and 3b extending partition 6. In connection to the longitudinal wall 5 is another, open on its longitudinal side chamber 7, in which a web-shaped hook strip 8 of an adjacent shutter profile engages, whereby an articulated connection between two or a plurality of shutter profiles 1 produced becomes. In this way, from a plurality of parallel, Extruded profile pieces a roller shutter, for example, for a wound up and unwound Pool cover, formed.

From an end face 9 of the shutter profile 1 ago this is by means of a closure 10th sealed watertight. The closure 10 consists of a cap 11, two piston plates 12a and 12b, two sealing bodies 13a and 13b and two connecting elements 14a and 14b. The cap 11 has a plate 15, a right-angled protruding therefrom Slide strip 16 and two plug portions 17a and 17b, as well as the piston plates 12a and 12b and the sealing body 13a and 13b to the cross section of the hollow chambers 3a and 3b are adjusted. The plug portions 17a and 17b penetrate with their entire length in the Hohlkammem 3a and 3b, whereas the plate 15 at the end faces of the shutter profile 1 supported.

The connecting elements 14a and 14b are integral with the respective piston plates 12a and 12b are connected and made of nylon. The top of the flexible rod-shaped connecting elements 14a and 14b are provided with barbs 18. It is also possible that the connecting elements are provided on both sides with such barbs 18. The connecting elements 14a and 14b do not penetrate the sealing bodies 13a and 13b represented breakthroughs in their cross-section of the cross section of the connecting elements 14a and 14b are adapted. In the same way penetrate these fasteners 14a and 14b and the cap 11 in the region of the plug portions 17a and 17b and the Plate 15 in adapted openings 19a and 19b (see Fig. 3). Located inside the plate 15 at the top of the openings 19 a and 19 b pawls 20 a and 20 b, with the barbs 18, the connecting elements 14a and 14b cooperate and a movement the same in the direction of arrow 21, prevent.

The sealing bodies 13a and 13b are made of a rubber-elastic plastic material a low hardness. The material is UV-resistant and temperature-resistant up to at least 100 ° C, since due to the sunlight on the upper and lower walls 22 and 23 of the shutter profile 1 not inconsiderable temperatures in the region of the closure 10 occur can. Examples of materials include silicone elastomers, fluoroelastomers, fluorosilicone elastomers or blend elastomers from the rubbers of the aforementioned elastomers or polyurethanes in question.

In Figures 1 and 2, the closure 10 is shown in its assembled state. The cross section the outer forces free sealing body 13 a and 13 b is the cross section of Hollow chambers 3a and 3b adjusted so that the pre-assembled closure 10 with his all items, as shown in Figs. 1 and 2, from the front end of the shutter profile 1, in these can be introduced. The transfer of the closure 10 and the sealing body 13a and 13b in the drawing state, not shown, is done in a simple manner Way, in which the connecting elements 14 a and 14 b against the direction of the arrow 21 from which are the Hohlkammem 3a and 3b pulled out, the cap 11 in its investment position is held on the front side 9 of the shutter profile 1. As a result of pulling out Of the connecting elements 14a and 14b, first the piston plates 12a and 12b pushed against the sealing body 13a and 13b and then these two components together against the plug portions 17a and 17b of the cap 11. Will the tensile force on the fasteners 14a and 14b after reducing the gaps 24a and 24b and 25a and 25b further increased to zero, it comes to an elastic or depending on the also selected material of the sealing body 13a and 13b to a plastic deformation thereof. Due to the pressure exerted in the longitudinal direction 2 of the hollow chambers 3a and 3b, which the sealing body 13a and 13b in the vertical direction from this, so that in succession the cross-sectional enlargement of the sealing body 13a and 13b, a circumferentially sealed system the same on the longitudinal walls 4 and 5, the partition 6 and the upper and lower Wall 22 and 23 of the shutter profile 1 takes place. Due to the tension in the connecting elements 14a and 14b generated compressive stress on the sealing body 13a and 13b, it also comes to a circumferentially tight system of facing each other planar frontal contact surfaces, the piston plates 12a and 12b and the sealing body 13a and 13b and the latter and the plug portions 17a and 17b of the cap 11. Auf this way, liquid is prevented from flowing along the connecting elements 14a and 14b through the apertures 19a and 19b in the plug portions 17a and 17b and through the Breakthroughs in the Dichtkörpem 13a and 13b in the interior of the hollow chambers 3a and 3b can penetrate.

The closure 10 'shown in FIG. 5 differs from that shown in FIGS. 1 to 4 merely in that the connecting elements 14a 'and 14b' as machine screws made of stainless steel with a Phillips countersunk head 26 are formed. The the cap 11 'opposite ends of the connecting elements 14a' and 14b 'act with nuts 27a and 27b, also made of stainless steel, together. These nuts 27a and 27b are encapsulated in the injection molding production of the piston plates 12a 'and 12b' with. The shortening of the distance between the piston plates 12a 'and 12b', the Dichtkörpem 13a 'and 13b' and the Stopfabschnitten 17a 'and 17b' of the cap 11 'takes place by turning the screws. The result of the compression of the sealing body 13 a 'and 13 b' occurred radial expansion and the seal thus achieved by appropriate Turn back the screws again canceled. So are the hollow chambers of such Closures 10 'sealed profiles accessible at any time without the need for sealing Destroyed and then again with replacement materials would have to be made.

In Fig. 6, yet another alternative closure 10 "is shown, in which the connecting elements 14a "and 14b" designed as screws with a self-tapping thread are. The cap 11 "facing away from the ends of the connecting elements 14a" and 14b " engage in blind holes 28a and 28b in the piston plates 12a "and 12b". The diameters the injection-molded blind holes 28a and 28b are smaller than the Diameter of the screws. While in the connecting element 14a "the thread extends over the entire shaft length of the screw, is the shank of the connecting element 14b "divided into a front part with thread and a rear part without such. The piston plate 12b "has a the sealing body 13b" facing system part 29b, whose cross section is adapted to the cross section of the hollow chamber 3b, and a rear Spigot portion 30b, whose cross-section is reduced compared to the opposite.

The assembly of the connecting elements 14a 'and 14b', 14a "and 14 designed as screws 14b ", preferably by means of torque-controlled tightening tools to a defined axial bias on the sealing body 13a 'and 13b', 13a "and 13b" to produce. The assembly of the closure 10 according to the figures 1 to 4 is preferably carried out by means of a pliers-like tool that initially preloads the rod-shaped Connecting elements 14a and 14b generated and upon reaching a certain tensile force - analogous to the operation of a blind rivet - a trimming or notching and Tearing off the protruding end of the connecting elements 14a and 14b causes. These can be provided at the appropriate position with a predetermined breaking point, the responds upon reaching a certain tensile stress.

Fig. 7 shows a closure 30, wherein the penetrated by a screw sealing body 33 has a shape which at both opposite end-side contact surfaces 35 'and 35 "each with a conical depression is provided both the piston plate 32nd as well as the cap 31 have in the region of the contact surfaces 35 'and 35 "conical Elevations that are complementary to the depressions in the sealing body 33. The at axial compression of sliding inclined surfaces cause a particularly favorable Implementation of the axial preload in a radial expansion of the sealing body 33rd

Finally, FIG. 8 shows yet another embodiment of a closure 40 in which the piston plate 42 and the cap 41 and also the substantially cylindrical and with a central through hole for the screw provided with sealing body 43, respectively In contrast to the previous one shown Dichtkörpem has the sealing body 43 of FIG. 8 has a ring in closed and outwardly closed cavity 46th This has the Shape of a torus with an oval cross-section. The wall thickness of the sealing body 43 in the area between the hollow body 46 and the wall of the shutter profile is smaller than the wall between the cavity 46 and the through hole for the screw. The comparatively thin outer wall causes in the sealing area a high flexibility, so that There a reliable plant, i. also sealing, can be achieved. It works the under axial pressure cavity 46 as a gas spring, the permanent maintenance the sealing effect guaranteed.

Claims (10)

1. An elongated roller shutter profile (1, 1") made of plastic or metal for swimming pool covers, comprising at least one water-proof closure (10, 10', 10", 30, 40) with which at least one hollow chamber (3a and 3b) extending in the longitudinal direction (2) of the roller shutter profile (1, 1") can be closed off on a face side (9) of the roller shutter profile (1, 1"), with the closure (10, 10', 10", 30, 40) comprising a cap (11, 11', 11", 31, 41) which is at least partly insertable into the hollow chamber (3a and 3b) from the face side (9) and comprises a piston plate (12a and 12b, 12a' and 12b', 12a" and 12b", 32, 42) disposed at a distance to the cap (11, 11', 11'') within the respective hollow chamber (3a and 3b) as well as a sealing medium extending between the cap (11, 11', 11", 31, 41) and the piston plate (12a and 12b, 12a' and 12b', 12a" and 12b", 32, 42), characterized in that the sealing medium is a sealing body (13a and 13b, 13a' and 13b', 13a" and 13b", 33, 43) made of an elastic and/or plastic material which based on a mounting state in which it can be introduced into the hollow chamber (3a and 3b) it can be brought into a sealing state by clamping between the piston plate (12a and 12b, 12a' and 12b', 12a" and 12b", 32, 42) and the cap (11, 11', 11'', 31, 41) in which it is expanded in a direction perpendicular to the longitudinal direction (2) of the hollow chamber (3a and 3b), so that it rests. in a circumferentially tight manner on the walls (4, 5, 6, 22, 23) delimiting the hollow chamber (3a and 3b).
2. A roller shutter profile according to claim 1, characterized by a connecting element (14a and 14b, 14a' and 14b', 14a" and 14b") which extends between the cap (11, 11', 11'', 31, 41) and the piston plate (12a and 12b, 12a' and 12b', 12a" and 12b", 32, 42) and is under tensile stress at least when transferring the sealing body (13a and 13b, 13a' and 13b', 13a" and 13b", 33, 43) into the sealing state.
3. A roller shutter profile according to claim 1 or 2, characterized in that it comprises several hollow chambers (3a and 3b) which are mutually separated by a separating wall (6) extending in the longitudinal direction (2) of the hollow body (1, 1'').
4. A roller shutter profile according to claim 3, characterized in that the closure (10, 10', 10", 30, 40) comprises a cap (11, 11', 11'', 31, 41) which is insertable into several hollow chambers (3a and 3b) simultaneously and to which is assigned a number of sealing bodies (13a and 13b, 13a' and 13b', 13a" and 13b", 33, 43) and piston plates (12a and 12b, 12a' and 12b', 12a" and 12b", 32, 42) corresponding to the number of hollow chambers (3a and 3b).
5. A roller shutter profile according to one of the claims 2 to 4, characterized in that the connecting element (14a and 14b, 14a' and 14b', 14a" and 14b") penetrates the sealing body (13a and 13b, 13a' and 13b', 13a" and 13b", 33, 43) and the cap (11, 11', 11", 31, 41) and is movable relative to the same in the longitudinal direction (2) of the hollow chambers (3a, 3b).
6. A roller shutter profile according to one of the claims 2 to 5, characterized in that the connecting element (14a and 14b, 14a' and 14b', 14a" and 14b") is a screw whose thread cooperates with the piston plate (12a and 12b, 12a' and 12b', 12a" and 12b", 32, 42).
7. A roller shutter profile according to one of the claims 2 to 5, characterized in that the rod-like connecting element (14a and 14b) is integrally joined with the piston plate (12a and 12b) and is provided on its surface with barbs (18) which cooperate with a detent pawl (20a and 20b) which is arranged in the cap (11).
8. A roller shutter profile according to one of the claims 1 to 7, characterized in that the piston plate (32) and/or the cap (31) is elevated in a conical way on its face-side contact surfaces (35', 35") facing the sealing body (33) and the sealing body (33) is conically recessed in a complementary manner on at least one of its two opposite face-side contact surfaces (35', 35") which correspond with the contact surfaces (35', 35") of the piston plate (32) and/or the cap (31).
9. A roller shutter profile according to one of the claims 1 to 8, characterized in that the sealing body (43) is provided with an annular, inherently closed hollow chamber (46) with gas filling, which chamber is closed off to the outside.
10. A closure (10, 10', 10", 30, 40) for the water-proof closure of an elongated roller shutter profile (1, 1") made of plastic or metal according to one of the preceding claims, with the closure (10, 10', 10", 30, 40) being insertable at least partly into at least one hollow chamber (3a and 3b) from its face-side opening and comprising a cap (11, 11', 11'', 31, 41) and a piston plate (12a and 12b, 12a' and 12b', 12a" and 12b", 32, 42) at a distance thereto within the respective hollow chamber (3a and 3b) and comprising a sealing means arranged between the piston plate (12a and 12b, 12a' and 12b', 12a" and 12b", 32, 42) and the cap (11, 11', 11", 31, 41), characterized in that the sealing means is a sealing body (13a and 13b, 13a' and 13b', 13a" and 13b", 33, 43) made of an elastic and/or plastic material which based on a mounting state in which it is insertable into the hollow chamber (3a and 3b), it can be transferred to a sealing state by clamping between the piston plate (12a and 12b, 12a' and 12b', 12a" and 12b", 32,42) and the cap (11, 11', 11'', 31, 41) in which it is extended in the direction perpendicular to the longitudinal direction (2) of the hollow chamber (3a and 3b), so that it rests in a circumferentially tight manner on the walls (4, 5, 6, 22, 23) delimiting the hollow chamber (3a and 3b).

Images