CH711198B1 - Insect protection door for a building opening. - Google Patents

Abstract

The invention relates to an insect protection door for a building opening with a closing device for a sliding door, the sliding door (4) having at least two door leaves (6a, 6b) which can be moved in a straight line relative to one another along a stationary guide rail of a sliding door frame, each having at least one holding element (26), between which an elastic rubber band (30) is stretched and guided, which is stretched when one of the door leaves (6a) is moved into an open position and which automatically moves the door leaf (6a) back into a closed position.

Description

The invention relates to an insect protection door for a building opening with a locking device for a sliding door, the sliding door having at least two door leaves which can be moved in a straight line relative to one another along a stationary guide rail of a sliding door frame.

Sliding doors are often used as interior doors or as a space-saving door element for partitions, cupboards or cloakrooms. Also known are insect protection devices with sliding doors or sash frames, which are installed in the area of building openings as a protection against insects, pollen or dirt. In particular in the area of large passageways, such as patio and balcony doors or in winter gardens, sliding doors are preferred compared to revolving doors, among other things for reasons of visual appearance.

Such insect protection doors are often designed as single or multi-leaf sliding systems, one or more door leaves being guided and / or mounted so that they can be displaced relative to one another along a straight guide rail. The sliding system typically comprises a stationary, rectangular assembly frame that encircles the building opening and is composed of a number of hollow profile strips. The hollow profile strips, which are often made of aluminum, serve as a tensioning frame for a protective fabric or protective grille, which is stretched between the hollow profile strips, for example via a welt arranged on the rear.

On the guide rail side, the door leaves have roller or slide elements as a displaceable linear bearing on the guide rail. This makes it possible for a user to open the door leaf by simply sliding it sideways, the door leaf being actively pushed back by the user in order to close it. The problem can arise here that the door leaf is not pushed back or not pushed back completely by the user, so that the sliding door is completely or at least partially open. In the case of an insect protection door in particular, the interior of the building is no longer protected from the ingress of insects, pollen or dirt.

As a remedy, an insect protection door with a locking device is therefore desirable, which automatically moves the door leaves from an open position into a closed position that closes the interior of the building.

The invention is therefore based on the object of specifying an insect screen door with a particularly suitable, automatically closing device for a sliding door.

[0007] According to the invention, this object is achieved by the features of claim 1. Advantageous refinements and developments are the subject of the dependent claims.

The inventive insect protection door comprises a closing device which is suitable and set up for the automatic closing of a sliding door with at least two door leaves which can be moved in a straight line against each other along a stationary guide rail of a sliding door frame. For this purpose, the locking device comprises an elastic rubber band which is stretched and guided between a number of holding elements. For this purpose, at least one holding element is arranged on one of the door leaves. The elastic band is guided between the holding elements in such a way that when one of the door leaves is moved into an open position, the elastic band is tensioned in such a way that, due to its elastic tensioning force, it automatically moves the door leaf - usually after an opening action has ceased to exist - into a specified closed position moved back. The closed position is to be understood in particular as a position of the door leaf in which it rests tightly and cohesively on the sliding door frame. In particular, a band-like, d. H. Understood rope or thread-like, elongated element made of an elastic material.

When the door leaf is opened, that is, when a door leaf is pushed sideways along the guide rail by a user, the elastic band is tensioned, and a tension or restoring force builds up as a result, which is applied to the opening door leaf by means of the holding elements works. If the door leaf is released by the user in an open or at least partially open position, this restoring force has the effect that the door leaf is moved back into the closed position. The elastic band relaxes and the restoring force is reduced so that the locking device is ready for use again when the sliding door is opened again.

The elastic band is designed in particular as a single rope or band-like tensioning element made of an elastic rubber material. Also conceivable is, for example, an embodiment with several one behind the other or next to one another, for example also stranded or twisted tensioning elements, which together act as a common elastic band, for example in the manner of an expander, for the sliding door.

A structurally simple and particularly inexpensive locking device is provided by the elastic band. The elasticity of the elastic band serves as a kind of energy store to which tension energy is fed when the door is opened, which can then be used as kinetic energy to close the sliding door.

The storage capacity is essentially given by the length and / or the elasticity of the elastic band. Furthermore, the restoring force of the elastic band, i.e. the force that counteracts the force exerted by the user to open the sliding door, as well as the restoring speed during a closing process in which the sliding door is moved back into the closed position by the tensioned elastic band, can be adjusted.

In a preferred embodiment, the length and elasticity of the elastic is preferably dimensioned such that the restoring force on the one hand is low enough that the door leaves can be easily moved into an open position by a user. Furthermore, a low restoring force ensures that the open door leaf is not moved too quickly into the closed position, so that there is no undesirable damage to the sliding door frame due to the door leaf being violently opened or struck against the sliding door frame. On the other hand, the restoring force is suitably chosen to be sufficiently large that the sliding door is closed as quickly as possible in order to counteract the ingress of insects, pollen or dirt into the interior of the building, for example when used in the area of a building opening.

In an advantageous embodiment, braking elements are provided on the guide rail side and / or on the sliding door frame side, which reduce the return speed of the elastic in the area of the sliding door frame sides (brake down). This advantageously counteracts violent opening or striking of the door leaf on the sliding door frame. Additionally or alternatively, damping elements can also be arranged on the sliding door frame, for example, which cushion the opening or hitting of the door leaf and / or dampen such that the closing door leaf does not bounce off the sliding door frame and remains in a partially open position.

In a preferred embodiment, the door leaf is formed from horizontal and vertical profile elements. Thus, the door leaf is particularly lightweight, which on the one hand makes it easier for a user to move, and on the other hand it can also be moved more easily and functionally into the closed position by the elastic band. This reduces the material requirements for the elastic band, which has an advantageous effect on manufacturing costs.

In a preferred embodiment, the profile elements are in particular hollow profile strips which can be cut to length and which can be assembled with one another by means of corner connectors to form a substantially rectangular frame. In particular, the sliding door frame is also preferably composed of such profile elements. As a result, a user can adapt the sliding door individually to the dimensions of a respective building opening by simply cutting or sawing the profile elements. For this purpose, the corner connectors, preferably also for the purpose of improved visual appearance, have overlapping collar elements to cover unclean cut edges or profile ends.

Preferably, at least the profile elements of the door leaves on the back, that is, on the side facing the building interior, a Keder groove for receiving a Keder element or the like, by means of which a protective fabric or protective grille can be stretched within the door leaf frame.

The stationary guide rail is suitably part of the sliding door frame and coupled to it in the manner of a horizontal profile element. The door leaf expediently comprises a roller or sliding guide in the area of the guide rail. The guide rail can be arranged on the sliding door frame, for example, on the top, bottom, or top and bottom. It is also conceivable that a separate guide rail is provided for each door leaf of the sliding door. In the case of a guide rail arranged only on one side, the door leaf in a preferred embodiment has a bearing on the side facing away from the guide rail, which counteracts an unintentional pivoting of the door leaf out of the sliding door frame.

In a suitable development, the holding elements are designed as corner connecting elements of the profile elements. The holding elements preferably have molded plug-in elements which can be at least partially inserted into corresponding profile chambers of the profile elements. Furthermore, it is desirable that the retaining elements have molded-on projections to cover the cut edges of the profile element ends.

In an expedient embodiment, the holding elements are arranged in the region of the guide rail. As a result, the elastic band is also positioned near the guide rail, which is beneficial to the stability of the door leaf on the guide rail during a closing process. In a preferred embodiment, the holding elements are arranged in the corner areas of the door leaf frame facing the guide rail. Alternatively, however, it is also conceivable for the holding elements to be arranged, for example, in the area of a door leaf central rung.

In an advantageous embodiment, the holding elements are screw-fastened in the horizontal profile elements. On the one hand, this improves the stability of the entire door leaf frame. On the other hand, a particularly secure fastening of the elastic is ensured. In particular, when the sliding door is open, where the elastic band is stretched and the greatest restoring forces act, reliable fastening by means of a screw connection is advantageous. This avoids the risk of the holding elements being torn out of the profiles of the door leaf frame by simple means.

In a particularly visually attractive development, the elastic band is at least partially guided within a horizontal profile element in the assembled state. As a result, the elastic band is suitably protected from external weather conditions or damage - for example from animals. On the one hand, this improves the longevity of the elastic band, and on the other hand, this advantageously reduces the risk of the elastic band tearing due to wear or damage. Furthermore, even in the event of a tear, the elastic band is guided within the profile element, so that it cannot reach the outside. In this way, personal injury or damage to nearby objects in the event of a rubber tear are advantageously and easily avoided.

In a suitable embodiment, the holding element has a sliding block-like sliding element for a sliding guide on the guide rail. As a result, the movable guide mounting of the door leaf is essentially implemented by the holding elements.

In an advantageous embodiment, the holding elements have a circumferentially extending guide groove for guiding the elastic band. The guide groove can be implemented, for example, on the outside of a housing of the holding element, but is preferably arranged at least partially within the housing to protect the elastic band.

For use as a locking device, it is particularly advantageous to use the longest possible elastic band with a high degree of extensibility, since this means that the tension is distributed more evenly and better along the elastic band when the sliding door is opened. On the one hand, this reduces the stress on the elastic band during use, which is beneficial to its longevity. On the other hand, the sliding door can thereby be pushed open by a user particularly easily. For this purpose, in a preferred embodiment, the elastic band is attached to a first holding element of the door leaf and guided horizontally along the door leaf to a second holding element. On the second holding element, the elastic band is preferably deflected by the guide groove in an approximately U-shape to the opposite side of the door leaf in the opposite direction. The second holding element acts in particular essentially as a reversing roller for the elastic band, whereby an elastic band can be used which is particularly long in the untensioned state.

In an advantageous development it is provided that the first and second holding elements of two adjacent door leaves are arranged on opposite door leaf sides so that the elastic band is guided approximately eight-shaped by the holding elements of the door leaves. In this development, one of the door leaves involved is preferably stationary.

In this development, a particularly long and stretchable elastic band can be used. The functional storage capacity for the locking function is ensured by the reversing roller-like guidance of the elastic band on the second holding elements. In this way, a pulley block-like construction is implemented, whereby the force required to slide open the sliding door is advantageously reduced due to the longer expansion path.

When the sliding door is opened, the moving door leaf is telescoped in the same direction towards the fixed door leaf so that the elastic band is stretched in the transition area from one door leaf to the other between the door leaves. In the fully opened state, in which the door leaves are arranged essentially so as to be superimposed, the elastic band is stretched by approximately the length of a door leaf. When the opening force is no longer applied, the elastic band contracts to its original length, so that the eight-shaped guide of the elastic band pulls the moving door leaf towards the closed position. In a possible further development, the elastic band is, for example, about 4.8 m long in the relaxed state and is stretched to about 6 m in length when the door is opened.

[0029] The frame structures of the door leaves are suitably covered with an insect screen fabric or insect screen.

Preferably, only one movable door leaf is provided, which can be displaced with respect to a fixed door leaf. However, a plurality of door leaves arranged in alignment or offset with one another can also be implemented. Here it is conceivable that each door leaf has its own locking device, or several door leaves can be brought into a closed position with one another by means of a locking device, for example by means of entrainment elements on the guide rail.

In the following, exemplary embodiments of the invention are explained in greater detail on the basis of a schematic and simplified drawing. Show in it: <tb> Fig. 1 <SEP> a perspective view of an insect protection device with a sliding door with two door leaves, a sliding door frame and a locking device in the area of the door leaf frame below, <tb> Fig. 2 <SEP> in a perspective illustration of the sliding door in the area of a guide rail on the underground side with attached holding carriage as a corner connector for the door leaf frame, <tb> Fig. 3 <SEP> a perspective view of a holding carriage with an elastic band, <tb> Fig. 4 <SEP> shows the holding carriage in an exploded view, <tb> Fig. 5 <SEP> in perspective a sectional representation of the elastic band between two adjacent holding carriages of the door leaves along the section line I-I in FIG. 1, <tb> Fig. 6 <SEP> in plan view the course of the elastic with closed door leaves, <tb> Fig. 7 <SEP> shows the course of the elastic band with the door leaves open, and <tb> Fig. 8 <SEP> in plan view an alternative course of the elastic band with closed door leaves.

Corresponding parts are always provided with the same reference numerals in all figures.

The insect protection device 2 shown in Fig. 1 comprises a sliding door 4 with two door leaves 6a, 6b and a sliding door frame 8. The fixed sliding door frame 8 is arranged in the area of a building opening for a balcony or terrace on a door reveal, not shown. The sliding door frame 8 comprises three hollow profile-like frame strips 10, which are arranged approximately U-shaped to one another by means of two corner connectors 12. On the underground side, the sliding door frame 8 has a guide rail 14. By means of the frame strips 10 and the guide rail 14, the sliding door frame 8 is designed in an approximately rectangular shape.

The door leaves 6a and 6b of the sliding door 4 have an approximately rectangular door leaf frame 16. The door leaf frame 16 is composed of two vertical strips 18 as long sides and two horizontal strips 20 as narrow sides. The door leaf frame 16 furthermore comprises a horizontal central rung 22 which is arranged approximately halfway up the vertical strips 18 and which extends essentially over the entire width of the door leaf frame 16. In the upper and lower half regions of the door leaf frame 16 formed as a result, a protective fabric 24 is clamped in as a protection against insects, pollen and dirt. For this purpose, the vertical bar 18, the horizontal bar 20 and the central rung 22 are designed as hollow profile bars, similar to the frame bars 10, which have receiving chambers (not shown in detail) for a piping for fastening the protective fabric 24. As an example, only one door leaf is provided with the reference symbols in the figures.

As is comparatively clear in FIG. 2, the door leaf frame 16 is assembled in the frame corner areas on the sub-floor by means of two holding carriages 26. The holding carriages 26 are arranged in the manner of a sliding guide for the door leaves 6a, 6b on two running rails 28a, 28b of the guide rail 14 arranged parallel to one another and spaced apart from one another. In the closed state of the insect protection device 2, the door leaf frames 16 of the door leaves 6a and 6b are at least partially arranged one above the other; in particular, due to the offset arrangement on the running rails 28a and 28b, the facing vertical strips 18 of the door leaves 6a and 6b are essentially stacked one above the other. In the assembled state, a band-shaped or rope-shaped elastic cord 30 is stretched between the holding carriage 26 as an essential component of an automatically acting locking device 32 for the sliding door 4.

The structure of the holding carriage 26 is explained in more detail below with reference to FIGS. 3 and 4. The holding carriage 26 essentially comprises a holding body 34 on the door leaf frame side as a corner connecting element and a sliding body 36 on the running rail side for slidable sliding bearing on the guide rail 14.

The holding body 34 has two vertically oriented plug-in elements 38. The essentially rectangular plug-in elements 38 are plug-connected in the assembled state in receiving chambers (not shown in detail) of the hollow-profile-like vertical strips 18. In the direction of the horizontal bar 20, the holding body 34 has a molded-on plug-in tab 40 which can be at least partially inserted into the horizontal bar 20. The holding body 34 comprises a protruding vertical projection 42 in this area. The projection 42 has two circular recesses 44 through which the holding body 34 can be securely fastened to the horizontal bar 20 by means of fastening screws not shown in detail.

A downwardly open receiving chamber 46 for receiving the sliding body 36 is integrally formed in the area of the holding body 34 on the subsurface side. As can be seen in FIG. 3, the sliding body 36 lies essentially completely within the receiving chamber 36 in the assembled state. For fastening, the sliding body 36 has an approximately central, hollow cylinder-like recess 48 through which a fastening screw can be screwed into a corresponding receptacle in the receiving chamber 36 on the underground side.

The approximately slot stone-like sliding body 36 has a guide groove 50 on the running rail side, which is essentially formed by a U-shaped recess open towards the ground. The guide groove 50 extends essentially over the entire length of the sliding body 36 and, in the assembled state, is aligned on the end face of the receiving chamber 36 facing away from the horizontal bar 20 in a recess 52 of complementary shape.

The essentially rectangular sliding body 36 has, on its end face facing the horizontal bar 20, an integrally formed nose-shaped extension 54 for easier placement of the sliding body 36 on the guide rail 14. On the surface of the sliding body 36 facing the vertical bar 18, a guide groove 56 for guiding the elastic band 30 is arranged on the circumferential side. The guide groove 56 has a rounded cross-section which corresponds approximately to a segment of a hollow cylinder. The guide groove 56 guides the elastic band 30 in an approximately U-shape within the receiving chamber 46, the receiving chamber 46 having a guide slot 58 in this area.

The guide slot 58 is arranged approximately halfway up the receiving chamber 46 so that the receiving chamber 46 has an approximately U-shaped shape from the side, the guide slot 58 extending from the end face of the receiving chamber 46 facing away from the horizontal bar 20. The recess 52 is expediently arranged on the U-leg on the underground side, the second U-leg facing the vertical strips 18 having a protruding projection 60 on the longitudinal side.

In the assembled state, the door leaves 6a and 6b are mounted upright on the running rails 28a, 28b of the guide rail 14 by means of two holding carriages 26a ', 26a and 26b', 26b. The door leaf 6b is fixed on the running rail 28b by fastening or locking means (not shown in detail) in the area of the guide rail 14 or the sliding door frame 8. The door leaf 6a can be moved in a straight line along the running rail 28a against the standing door leaf 6b by a user in order to open the sliding door 4. To this end, the door leaf 6a can be displaced with the aid of a handle element (not shown in detail) in the area of the central rung 22 with a laterally directed impact.

When the sliding door 4 is opened, the elastic band 30 is tensioned, with the sliding door 4 being automatically moved into a closed position by the locking device 32 after the application is no longer applied. The mode of operation and the structure of the locking device 32 are explained in more detail below with reference to FIGS. 5, 6 and 7.

Fig. 5 shows a section through the holding elements 26 in the area of the overlapping vertical strips 18 of the door leaves 6a and 6b. In the closed state of the sliding door 4, the holding carriage 26a from the lower right corner area of the door leaf 6a and the holding carriage 26b of the lower left corner area of the door leaf 6b are positioned next to one another, essentially opposite one another, on the running rails 28a and 28b. The holding carriages 26a and 26b are thus arranged on the guide rail 14, oriented essentially opposite one another.

The sectional view shown is arranged approximately at the level of the guide slot 58 and shows comparatively clearly an approximately Z-shaped course of the elastic (rubber cord) 30 between the holding carriages 26a and 26b, the horizontal Z-bars essentially parallel to the door leaves 6a and 6b are oriented. As is comparatively clear here, the cross section of the guide slot 58 is dimensioned large enough that the elastic band 30 can be passed through.

In particular, the Z-shaped course is formed in that the elastic band 30 is diverted from the guide groove 56 of the holding carriage 26a in the manner of a pulley approximately U-shaped, so that it runs in the opposite direction on the opposite side of the door leaf. Directly after the U-shaped deflection curve, the elastic band 30 is guided out of the guide slot 58 of the holding carriage 26a along the inclined Z-bar into the guide slot 58 of the holding carriage 26b. In the holding carriage 26b, the elastic band 30 is guided in a U-shape through the guide groove 56 onto the rear side of the door leaf 6b.

Fig. 6 shows a schematic plan view of the door leaves 6a, 6b and the elastic band 30 in the closed position. In this context, the closed position is to be understood as meaning a position of the door leaves 6a, 6b in which the interior of the building is completely covered by the insect protection device 2. As can be seen in FIG. 6, the door leaves 6a and 6b are arranged essentially next to one another in the closed position, whereby they essentially overlap one another on the vertical strips 18 facing one another.

The elastic 30 is attached at one end in a manner not shown to the two sliding door frame-side holding carriages 26a 'and 26b' of the door leaves 6a and 6b. The elastic band 30 is attached to the holding carriage 26a 'on the outside of the building and is deflected in a U-shape by its guide groove 56 onto the surface of the door leaf 6a on the inside of the building. The elastic band 30 runs through a corresponding groove or receiving chamber of the horizontal bar 20 essentially horizontally and parallel to the door leaf 6a to the holding slide 26a. In the area of the holding carriage 26a, the elastic band 30 is transferred according to the above-described Z-shaped course by the holding carriages 26a and 26b to the surface of the door leaf 6b on the outside of the building. The elastic band 30 runs within the horizontal strip 20 of the door leaf 6b to the holding carriage 26b ', on which it is diverted in a U-shape by the guide groove 56 and is attached to the holding carriage 26b' on the inside of the building.

As a result, an approximately eight-shaped course of the elastic band 30 is realized on the sliding door 4, wherein when the sliding door is opened - as can be seen in FIG. 7 - in particular the inclined Z-bar in the transition area between the holding carriages 26a and 26b is stretched . As a result, a restoring force is built up which moves the door leaf 6a back into the closed position after the opening action has ceased.

In Fig. 8 an alternative guidance of the rubber cord 30 is shown with the door leaves 6a and 6b closed. In this embodiment, the elastic band 30 is not attached to the holding carriages 26a 'and 26b' on the sliding door frame side, but rather in a region of the holding carriages 26a and 26b, respectively. As a result, the elastic band 30 is made longer by approximately the width of the door leaves 6a and 6b than in the variant above. By varying the fastening point, it is possible for a user, for example, to adapt the restoring force or the restoring speed of the closing device 32. For this purpose, for example, additional sliding block-like fastening elements (not shown) for fastening the elastic band along a horizontally running groove in the horizontal bar 20 can be provided.

In a suitable embodiment, the profile strips of the sliding door frame 8 and the door leaf frame 16 are designed as aluminum components that can be cut to length. For this purpose, the protrusions 42 and 60 of the holding carriage 26 project so far beyond the vertical strips 18 and horizontal strips 20 that the cut edges and ends of the profile strips are covered in an optically inconspicuous manner.

In the first exemplary embodiment, the elastic band 30 is approximately 2.4 m long in a suitable dimension in the relaxed state, which corresponds approximately to the width of the two door leaves 6a and 6b. In the fully opened state, the elastic band 30 is stretched essentially by the width of the door leaf 6b, so that the elastic cord 30 is approximately 3.6 m long.

For the second exemplary embodiment, the length of the elastic band 30 in the relaxed state is approximately 4.8 m and in the open state approximately 6 m. Here, for the purpose of increased flexibility, it is conceivable that the elastic band 30 can be cut to length so that the insect protection device 2 can be adapted to the dimensions of a respective building opening, or a selection between the two fastening points of the exemplary embodiments is made possible.

List of reference symbols

2 insect protection device 4 sliding door 6a, 6b door leaf 8 sliding door frame 10 frame strips 12 corner connector 14 guide rail 16 door leaf frame 18 vertical bar 20 horizontal bar 22 middle rung 24 protective fabric 26, 26a, 26a ', 26b, 26b' holding carriage 28a, 28b running rail 30 elastic cord / rope 32 Closing device 34 Retaining body 36 Sliding body 38 Plug element 40 Tuck-in tab 42 Overhang 44 Recess 46 Recess chamber 48 Recess 50 Guide groove 52 Recess 54 Extension 56 Guide groove 58 Guide slot 60 Overhang

Claims (10)

1. Insect protection door (2) for a building opening, with a closing device (32) for a sliding door (4), the sliding door (4) at least two door leaves (6a) which can be moved in a straight line relative to one another along a stationary guide rail (14) of a sliding door frame (8), 6b), characterized, that the door leaves (6a, 6b) each have at least one holding element (26), between which an elastic rubber band (30) is stretched and guided, which is tensioned when one of the door leaves (6a) is moved into an open position, and which holds the door leaf ( 6a) automatically moved back into a closed position. 2. insect protection door (2) according to claim 1, characterized, that the door leaf (6a, 6b) is formed from horizontal and vertical profile elements (18, 20). 3. insect protection door (2) according to claim 2, characterized, that the holding elements (26) are designed as corner connecting elements of the profile elements (18, 20). 4. insect protection door (2) according to claim 2 or 3, characterized, that the holding elements (26) are arranged in the region of the guide rail (14). 5. insect protection door (2) according to one of claims 2 to 4, characterized, that the holding elements (26) are screw-fastened in the horizontal profile elements (20). 6. insect protection door (2) according to one of claims 2 to 5, characterized, that the elastic band (30) in the assembled state is at least partially guided within a horizontal profile element (20). 7. insect protection door (2) according to one of claims 1 to 6, characterized, that the holding elements (26) have a sliding block-shaped sliding element (36) for a sliding guide on the guide rail (14). 8. insect protection door (2) according to one of claims 1 to 7, characterized, that the holding elements (26) have a circumferentially running guide groove (56) for guiding the elastic band (30). 9. insect protection door (2) according to one of claims 1 to 8, characterized, that the elastic band (30) is attached to a first holding element (26a ', 26b') of the door leaf (6a, 6b) and is guided horizontally along the door leaf (6a, 6b) to a second holding element (26a, 26b), the second Holding element (26a, 26b) deflects the elastic band (30) approximately in a U-shape onto the opposite side of the door leaf in the opposite direction. 10. insect protection door (2) according to one of claims 1 to 9, characterized, that first and second holding elements (26a, 26a ', 26b, 26b') of two adjacent door leaves (6a, 6b) are arranged on opposite door leaf sides, so that the elastic band (30) of the holding elements (26a, 26a ', 26b, 26b') the door leaf (6a, 6b) is approximately eight-shaped.