EP2698334B1 - Rail system for elevator sliding doors - Google Patents

Description

The invention relates to an elevator door guide system according to the preamble of claim 1.

The international patent application WO 2005/09884 A1 proposes an elevator door guide system for a telescopic elevator door, in which each door panel hangs on a carriage, which is hung with its overhead guide rollers in a guide rail. All guide rollers are the same size. At least the carriage of the faster-moving panel has additional, counter-rollers at the bottom, which prevent unintentional unhooking of the carriage and especially his commuting due to strong acceleration or deceleration. The two guide rails are connected together by an aligned row of centrally-penetrating screws and with a separate bracket for wall mounting the elevator door guide system. So, as the screw has been specifically implemented here, the screws are exposed to a significant bending moment. They are therefore, as well as the guide rails themselves, correspondingly massive dimensions. This means that in particular in the vertical direction in addition to the space required by the guide and counter rollers anyway, further space is required, which is consumed exclusively by the guide rails and their screwing.

The British patent UK 738 846 proposes a comparable elevator door guidance system, which differs from the aforementioned patent application WO 2005/09884 Al differs essentially only in that the guide rollers of the slower running carriage have a smaller diameter to make room for the rope drive, with which the faster carriage drives the slower.

Both known elevator door guidance systems are obviously quite generous with the installation space they require, both in the vertical and in the horizontal direction.

Known are connecting elements of Kölbel Präzisionsdreherei, which have on one end side a protruding connecting pin with an external thread and on the other end a threaded hole.

The Chinese utility model application CN 201834637 U proposes a solution that, in principle, corresponds to the solution that describes the two previously mentioned documents. However, an attempt is being made to make the construction less expensive by omitting the solid guide rails. Instead, a tubular, circumferentially self-contained guide rail is used. This actually saves material. However, the production of the tubular, quite complicated shaped guide rail increases the production cost.

The design proposed by the Chinese utility model does not take into account how much space 20 is consumed, especially not in the vertical direction.

In contrast, it is the object of the invention to provide a compact designed elevator door guide system.

The solution of this object is achieved by the features of claim 1.

The elevator door guide system according to the invention consists of at least two guide rails arranged side by side with respect to the opening and closing direction. The guide rails are therefore at least substantially at the same height. Ideally, the guide rails lie completely at the same height and thus aligned in the horizontal direction. The guide rails are connected to each other by connecting elements, which are preferably formed by the connection element system to be explained later, which includes special connecting bolts and end screws.

On the guide rails carriages are guided. These typically consist of a single or multi-part sheet metal plate and are therefore also called hanger plate. Of course, door panels with integrated hanger plate are conceivable.

According to the invention an inner carriage is guided on smaller rollers. Under rollers are understood to mean those roles in which the carriage is suspended. Smaller these rollers compared to the diameter of the larger rollers, with the help of an outside carriage is performed, where it comes for the terms "smaller" and "larger" as a rule to the maximum diameter at the outermost circumference of the respective rollers. As internal a carriage is called, which is arranged between two guide rails.

The invention is characterized in that the space above or below the smaller rollers accommodates at least one connecting element, by means of which a plurality of guide rails are connected to one another and if necessary also the same with the shaft wall or a carrier element to be fastened to the shaft wall, in which it is preferably a carrier sheet. In this case, this connecting element is arranged so that the smaller rollers roll in the course of the opening or closing movement under said connecting element, while the larger rollers of the other carriage said connecting element happen laterally.

It is thus so that space is saved in a simple manner by the use of smaller rollers for the inner carriage, which is used to provide in the area used by the carriages at least one connecting element, which for an even more rigid attachment of two or more guide rails together, without requiring additional space.

As a result, the guide rails can better brace against each other to a bending load as a unit-defying package, so that not least a higher stability against force effects is achieved, as they arise when the door panels are loaded in a horizontal direction, such as by people who lean on the door panel. This makes it easier to use the guide rails as sheet metal parts instead of massive profiles. In particular, there are also in the execution of the guide rails as laterally open, d. H. non-tubular, less torsional problems.

Advantageously, the smaller diameter rollers are those on which the slower moving carriage is suspended. The slower moving carriage only covers half the distance in each opening and closing operation, which is why its rollers are naturally subject to less wear than that of the faster running carriage. This embodiment of the invention is based on the recognition that larger rollers are less susceptible to wear, but it makes no sense to run the less-loaded wheels of the slower running and within the product life only a smaller way traversing carriage as large as that of the faster running carriage.

In certain cases it will be chosen by the differently chosen Roller diameter possible to run the rollers of the faster running carriage so large that they can be made of plastic, without risking excessive wear. The smaller rollers are then also made of plastic or advantageously made of metal.

Preferably, the guide rails are connected at their seen in the direction of the left and right ends by at least two connecting elements with each other, which are aligned along an imaginary first line with each other, which extends transversely, preferably perpendicular to the direction.

Ideally, at least one additional connecting element for connecting the two or more guide rails is provided at the same time along an imaginary second line which extends at least substantially parallel to the running direction, each with at least one connecting element connecting the right and left ends of the guide rails flees.

In this way, unlike in the prior art, the guide rails are not pressed against each other only in a single plane by the connecting elements. Rather, the connecting elements are spatially distributed in such an arrangement such that the guide rails are connected by the connecting elements at both horizontally and vertically spaced points by the connecting elements and preferably compressed. This results in an overall stiffer unit.

Preferably, it is such that the bearing axis of the larger rollers seen in the vertical direction is arranged above the bearing axis of the smaller rollers. In this way, the space that can be optimally used on the side of the large rollers of the fasteners in Claimed.

Conveniently, the internal, d. H. the on the side facing away from the elevator shaft carriage with the smaller rollers one who runs in the space between two adjacent guide rails. This applies both when the elevator door guide system according to the invention is used to realize a landing door, as well as when it is used to realize a car door.

It goes without saying that the elevator door guide system according to the invention can also consist of three or more adjacent guide rails. It is then preferably such that the innermost carriage seen from the shaft side is guided on rollers with a larger diameter, while all other carriages have rollers whose diameter is smaller than that of the large rollers. In this case, run several moving in parallel planes carriages with small rollers in the various spaces between guide rails.

Preferably, a multi-part connector system is used for the elevator door guide system. It comprises at least one connecting bolt, which has a main portion, which is provided on its one end face with a threaded bore. From the connecting bolt is on the other end face from a threaded pin whose outer diameter is smaller than the outer diameter of the main portion of the connecting bolt. In this case, the threaded bore and the threaded pin are preferably matched to one another such that a plurality of identical connecting bolts can be screwed into one another in such a way that they have a common longitudinal axis. The system may include connecting bolts of different overall length, whereby the distance between the individual guide rails in each case from each other comply, can be varied.

To the connecting element system preferably also include additional end screws having a flat head whose thickness in the direction of the screw longitudinal axis is smaller than 1.5 times the thickness of the guide rail at the screwing, also measured in the direction of the screw longitudinal axis. Such end screws are particularly useful when using guide rails made of sheet metal. They take away little space in the horizontal direction without the need to make a countersink that would be difficult to produce in a sheet-metal profile for countersinking the screw head.

With the help of this fastener system, an equally convenient and accurate mounting of the individual guide rails is possible. This is particularly noticeable there positively noticeable, where more than just two guide rails are to be arranged side by side. The connecting bolts make it possible to mount side-by-side guide rails one after the other, thereby making it easier to achieve accurate parallel alignment of the guide rails.

First of all, a first guide rail is screwed to the corresponding carrier unit with the aid of the described connecting bolts. The guide rail is thereby clamped between the carrier unit and the connecting bolt at the point at which the threaded pin of the connecting bolt merges into its main section, which has a larger diameter. The main section is preferably provided with a shoulder surface for a screwing tool. After the first guide rail has been fixed in this manner by means of a plurality of connecting bolts, the next following guide rail is applied to the still free end faces of the first guide rail holding connecting bolts, so that the corresponding mounting holes of the second guide rail with aligned with the threaded holes of the already set connecting bolts. Then another similar connecting bolt is screwed into each of the threaded holes of the already set connecting bolt, so that two in the horizontal direction arranged one behind the other and screwed together connecting bolts hold between the second guide rail clamped. If a total of only two juxtaposed guide rails are to be used, the screw is not using a respective second connecting bolt, but with the help of a belonging to the fastener system end screw inserted through the mounting hole of the last to be mounted guide rail and then into the threaded hole of the connecting bolt is screwed in. This end screw is preferably equipped with the above-mentioned flat head.

Preferably separately, ie also alone, detached from the rest of the laid down in the main claim invention, a guide rail for an elevator door guide system is claimed, which is designed as a sheet metal bent part and has a downwardly open U-section section, which in turn has a tread for includes the guide rollers of a door panel. In this case, the guide rail according to the invention also has a secondary section, which forms a running surface for the counter-rollers of the aforementioned door panel. The secondary section and the U-profile section are integrally connected to each other, ie they represent a unitary sheet metal bent part, so they are not caused by screwing or welding two initially separate from each other usually produced by bending or rolling items. This guide rail is characterized by the fact that at least one leg of the UProfil section directly adjoining the tread of the roller that has passed the roller has an acute angle α with the secondary section includes. It is even preferable that the entire U-profile section, which in cross-section consists of a circular section functioning as a running surface and two legs, preferably completely rectilinear, adjoining it on both sides, is inclined towards the side of the secondary section. In this way, the sub-section and the U-profile section do not come to lie completely next to each other, but the U-profile section is at least partially, preferably more than 20% of its extension, in the vertical direction over said side section, although the profile of the guide rail in cross-section is not closed in itself, but open to the side. As a result, space is saved in horizontal shaft inward direction. This is of great interest, since the efforts in modern lifts go to keep the cross-sectional area of the shaft as small as possible in order to have a maximum of converted building space available for other purposes or in predetermined or existing shaft cross-sections to realize the largest possible car.

Further details of how the claimed guide rail can be configured in addition to the just described, the description of the embodiments can be seen.

Quite generally applies to all aspects of the invention that further design options, advantages and modes of operation of the description of the embodiment with reference to the figures can be seen.

The Fig. 1 shows an elevator door guide system according to the invention with two of the likewise inventive guide rails seen from one end side.

The Fig. 2 shows a side view of the same elevator door guide system.

The Fig. 3 shows an enlarged section Fig. 2 to explain the angle described.

The Fig. 4 shows a section through a connecting element system according to the invention for connecting three horizontally adjacent guide rails to an overall stiffer unit.

How best to use the Fig. 2 sees, the elevator door guide system 1 according to the invention in this embodiment comprises two juxtaposed and braced together to form a unit guide rails 25. The same length guide rails 25 are at the same height and aligned with each other in the horizontal direction.

The guide rails preferably have an identical profile or an identical cross section.

Each of the guide rails 25 is preferably provided with a number of fastening holes 4 for receiving connecting elements, which is greater than the number of each used in the concrete case for connection connecting elements, ideally at least by a factor of 5. The mounting holes 4 are ideally after one certain, recurring grid arranged. Preferably, seen in the horizontal direction at least two parallel rows of aligned mounting holes 4 are provided. Typically, each of the guide rails 25 of the invention has between 16 and 48 mounting holes 4.

In this way, the guide rails 25 can be easily cut to the length required for the particular case, without losing their ability to waive to be screwed together on the drilling of individual holes. So it can be realized in the context of ongoing production without excessive effort a special length. Even a shortening of the guide rails 25 on site on the site is technically possible, for. B. if in the rehabilitation of old systems on exceptional shaft cross-sections consideration must be taken, so that the side of the door opening to be installed end of the guide rails is not completely in the shaft space. The guide rails 25 are screwed together in a special way. At its seen in the direction of the right and left end of the guide rails are each screwed together by at least two in the figures by means of an arrow and the reference numeral 2 marked fasteners. These are aligned along a first direction, like the one in Fig. 2 is visualized by the line R1. In addition, the guide rails are connected to each other in their uppermost quarter when properly mounted by preferably at least two further connecting elements 2. Ideally, in the upper quarter of each of the guide rails even align at least 4 fasteners 2 in a second, horizontal direction, which in Fig. 2 is visualized by the line R2. Preferably, the imaginary lines R1 and R2 form a right angle with each other.

The inventive, special type of arrangement of the connecting elements 2 is possible by the inventive design of the rollers 7 and 8, which is best based on the Fig. 1 let explain.

Good to see here are the inner carriage 5 and the outer carriage 6. The outside, the opening and closing the way further and therefore faster running carriage 6 is suspended on larger rollers 8 as the inner carriage 5, the smaller rollers 7 is suspended. Ideally, each of the rollers has on its periphery a concave rolling surface which engages a convex shaped portion of the guide rail 25 and thereby provides the necessary lateral guidance. This convex shaped portion, which distinguishes the guide rail according to a further aspect of the invention will be described in more detail later.

The two carriages are coupled in a conventional manner by a cable drive 11 with each other, so that the directly driven, faster moving carriage 6 the other carriage 5 mitschleppt at half speed.

As can be seen, each of the carriages 5 and 6 is equipped with a plurality of counter rollers 12, which prevent the unhooking of the carriage and the oscillation of the door panel in the opening and closing direction, z. B. during rapid braking of the door panel. The smaller rollers 7 allow the inventive positioning of the fasteners 2. The vacated by the diameter reduction in this embodiment above the smaller rollers 7 space takes those fasteners 2, ie in the concrete embodiment those connecting pin 2.1, which in addition between an extreme right and an outermost left connecting element 2 and connecting pin 2.1 were installed and which are actually within the normally traveled by the rollers of a carriage area, see. also Fig. 1 , Due to their reduced diameter, the smaller rollers 7 can roll under these connecting elements 2 or connecting pin 2.1, while the larger rollers 8 of the other carriage pass through these connecting elements 2 or connecting pin 2.1 laterally. This lateral passage is preferably such that the annular surface of the larger roller 8, which is between Rmax and Rmax / 2 of the larger roller 8, when passing the Connecting element 2 or connecting pin 2.1 this is directly opposite, wherein the end face of the connecting element 2, that is here the end screw 3, also not on the said annular surface outwardly protrudes, see. Fig. 1 ,

The bearing axes of the smaller and larger rollers 7 and 8 bear the reference numerals 9 and 10 and are evidently the Fig. 1 arranged offset from one another. The bearing axes of the larger rollers are seen in the vertical direction above the bearing axes of the smaller rollers, so that the larger and smaller rollers roll at the same height on their associated guide rails.

Each of the carriages 5 and 6 has two or more laterally downwardly projecting from it Hänggesicherungen 13, which engage in later later to be explained manner laterally behind the guide rail and thereby ensure that the respective carriage 5 and 6 and thus the respective door panel remain suspended even if one or more rollers 7 or 8 on the guide rail. With careful comparison of Fig. 1 and 2 It can be seen that each of the suspension fences 13 is suitably formed as a top side defined, freely downwardly projecting sheet metal tabs, which is caused by a notched to the side of the sheet metal of the respective carriage 5 and 6 respectively. This allows a very rational production.

It is worth noting that for screwing the bearing shafts 9 of the smaller rollers 7 for reasons of space preferably each one of the fastener system belonging end screws 3 is used, which is preferably used in this embodiment.

Also noteworthy are the guide rails 25 used for this elevator door guide system, of which protection is claimed for each as such, ie in isolation.

The respective guide rail 25 is designed at least in the region of the running surface 28 for the counter-roller and the U-profile section 31, which provides the running surface for the roller, as a one-piece bent sheet metal part or as a rolled sheet metal component. As a rule, the guide rail is even designed as a one-piece component. In this case, sheets are preferably used, which have a thickness between 2 mm and 4 mm prior to bending.

As you can see, the guide rail is not self-contained tube-like, but on more than 25%, better more than 50%, of its lateral surface unilaterally open, d. H. here in the vertical direction only one layer executed.

The single guide rail 25 is extremely narrow in the bay direction; In that regard, it has a width which is preferably less than or equal to 1.7 times the width of the rollers 7 and 8, respectively, which interact with them as intended.

How to use the Fig. 1 sees, the guide rail 25 has a main portion 26 which extends vertically in the intended state mounted. The main portion 26 is preferably or at least substantially straight. At its lower end, the main portion 26 is on all or at least over its predominant length in a first bend 27, which is preferably 90 °. At this bend 27 is followed by the tread for the counter-rollers, which is formed by a first straight side portion 28. This straight side section is preferably only Slightly wider than the contact surface of the counter-rollers, which roll as intended on him. Insignificant in the sense of the invention is to be understood here as a span of +/- 20% and preferably of +/- 10%. The first secondary section 28 is adjoined by a second angled section 29, which in turn merges into a section of which a part forms the running surface for the guide rollers which roll on this guide rail and which essentially has the shape of a downwardly open U-profile , ie the shape of a circular ring section with both sides adjoining, straight legs. This section is collectively referred to as U-profile section 31.

A peculiarity is that the first side section 28 and the U-section section, or at least its legs facing the side section 28, enclose an acute angle α between them, instead of being at right angles to each other. Preferably, 50 ° ≤ α ≤ 80 °, whereby ideally values of 60 ° ≤ α ≤ 70 ° are maintained. Ideally, the U-profile section is inclined as a whole to the main section, as well as the Fig. 1 shows, the details with respect to said angle of the cut-out magnification according to Fig. 3 to be shown.

Such a configuration makes it possible to provide a wide running surface for the counter-rotating rollers 12 without making the guide rail 25 excessively wide in the horizontal direction transversely to the running direction of the carriages 5 and 6. The rollers 7 and 8 of a carriage 5 or 6 and its counter-rollers 12 are not in alignment in the vertical direction, but offset from each other, preferably by an amount corresponding to about 40% to 60% of the width of the counter-rollers 12, see , Fig. 1 , This ensures good support of the respective trolley 10 by its counter-rollers 12.

As can be seen from the figures, engage in the space between the U-profile section 31 and the main portion 26, the above-described suspension fuses 13 a.

Another also best on hand Fig. 3 and Fig. 1 to be recognized special feature is that the executed as a rounding section, which connects the two straight legs of the U-profile section 31 with each other, describes more than a semicircle, so that the two legs of the U-section section 31 include an acute angle β, for which preferably has β ≥ 8 °, cf. Fig. 3 , Ideally, even β ≥ 10 ° and β ≤ 20 °. In this way, the contact area available for the guide rollers on the U-section section for unrolling is increased.

As can be seen with reference to the figures of the embodiment, the guide rollers 7, 8 each have a circumferential concave guide groove, the surface with the rounded portion running, which connects the two legs of the U-section section, engage, whereby the required Side guide is guaranteed. Characterized in that the said rounding describes an angle of more than 180 ° and thus the legs of the U-section section 31 can include an acute angle β, the contact surface available for the guide rollers is not reduced, although the U-profile section 31 from the above Total ground inward, inclined towards the main section.

The leg of the U-shaped section 31 facing away from the secondary section 28 transitions, preferably via a third, very small angled section ≦ 10 °, into a second, preferably straight secondary section 32, which ends in the vertical direction below the running surface for the counter-rotating roller. As a result, the second secondary section constitutes a safety device which prevents the counter-rollers from sliding in the direction of the shaft can derail, for. B. as a result of violence from the car door inside or the shaft door outside.

At its upper end, the main section 26 merges on its entire or at least its predominant length into a fourth bend 33, which is followed by a preferably horizontally extending, third secondary section 34, which is expediently straight.

The Fig. 4 shows the inventive and also on its own, without the other features of the main claim claimed fastener system. This fastener system becomes at Fig. 4 shown embodiment used to brace three guide rails 25 together and optionally attach to the common carrier or to the wall.

For this purpose, the connecting element system comprises two connecting bolts 2.2 and one end screw 3.

How to use the Fig. 4 sees, is on the left a first guide rail 25 (for example, the Fig. 1 shown type), for example, has one of the above-described mounting holes 4, which is penetrated by the threaded pin 2.3, which projects at one end of the main section 2.2 of the connecting pin 2.1. With the help of this threaded with a connecting pin 2.3, the whole assembly can be mounted on the wall or on a common support member. This is followed by another connecting bolt 2.1 seen from the right, which is screwed into the internal thread 2.4 of the first connecting bolt (left), so that the first and the second connecting pin 2.1 hold the central guide rail 25 between them. On the far right, a further guide rail 25 is applied to the end face of the right-hand connecting pin 2.1, which is there with Help the end screw 3 is held, which in turn is screwed into the female threaded portion 2.4 of the right connecting bolt 2.1.

In this connection, it should be noted that the elevator door guide system is intended for both car doors and landing doors. This also applies to the guide rail, as far as it is claimed as a single part.

Finally, it is stated that a protection is claimed for a guide rail (25) for an elevator door guide system (1), which is designed as a sheet metal bent part and has a downwardly open U-section section (31), which in turn has a tread for the guide rollers (7, 8) of a carriage (5, 6), the guide rail (25) further having a secondary section (28) forming a running surface for the counter-rollers (12) of the aforesaid carriage (5, 6), characterized in that at least one leg of the U-shaped section (31) encloses an acute angle a with the secondary section (28). This claim may be supplemented by further features from the claims associated with this application or from the foregoing description.

LIST OF REFERENCE NUMBERS

1

Elevator doors guidance system

2

connecting element

2.1

connecting bolts

2.2

Main section connecting bolt

2.3

Threaded pin of the connecting bolt

2.4

Internal thread of the connecting bolt

3

end screw

4

Mounting holes in the guide rails

5

Internal carriage

6

Outboard carriage

7

Small roller

8th

Big caster

9

Bearing axis of the small roller

10

Bearing axis of the large roller

11

cable drive

12

counter-roller

13

suspension fuses

14 - 24

not forgiven

25

guide rail

26

main section

27

First bend

28

First subsection

29

Second bend

30

not forgiven

31

U-profile section

32

Second side section

33

Fourth bend

34

Third subsection

α

Angle between the first minor section and a leg of the U-profile section

β

Sharp angle between the legs of the U-profile section

S

shaft side

F

Car side or floor side

R1

Line first direction

R2

Line second direction

Claims (9)

1. An elevator door guiding system (1) consisting of at least two guide rails (25), which are disposed side-by-side with respect to the opening and closing direction and are interconnected by several connecting members (2), and at least two carriages (5, 6) guided thereon, wherein an inner carriage is guided on smaller rollers (7) whose diameter is smaller than the diameter of the larger rollers (8) by means of which an outer carriage (6) is guided, characterised in that the space above the smaller rollers (7) accommodates at least one connecting member (2) and the connecting member is disposed in such a way that the smaller rollers (7) roll through under the connecting member (2) or roll over the connecting member (2) during the course of the opening and closing movement, whereas the larger rollers (8) pass said connecting member (2) laterally.
2. The elevator door guiding system (1) according to claim 1, characterised in that the bearing axis (10) of the larger rollers (8), seen in the vertical direction, is disposed above the bearing axis (9) of the smaller rollers (7).
3. The elevator door guiding system (1) according to any one of the preceding claims, characterised in that an inner carriage (5) with smaller rollers (7) runs in the intermediate space between two adjacent guide rails (25).
4. The elevator door guiding system (1) according to any one of the preceding claims, characterised in that the guide rails are interconnected at their left-hand and right-hand ends respectively by at least two connecting members (2) which are aligned with each other along an imaginary first line (R1) that extends transversely, preferably perpendicularly, to the running direction of the carriages.
5. The elevator door guiding system (1) according to any one of the preceding claims, characterised in that the guide rails (25) are interconnected by at least one additional connecting member (2) which is aligned, along an imaginary second line (R2) that extends at least substantially parallel to the running direction, with a connecting member interconnecting the left-hand and the right-hand ends of the guide rails (25).
6. The elevator door guiding system (1) according to any one of the preceding claims, characterised in that each of the connecting members (2) consists of several parts and comprises at least one connecting bolt (2.1) having a primary section which is provided on its one end face with a tapped hole and from whose other end face a threaded bolt protrudes, whose external diameter is smaller than the external diameter of the primary section, the tapped hole and the threaded bolt preferably being adapted to each other in such a way that several connecting bolts can be screwed into one another.
7. The elevator door guiding system (1) according to any one of the preceding claims, characterised in that each of the connecting members (2) consists of several parts and comprises at least one end screw (3), which has a flat head whose thickness in the direction of the longitudinal screw axis is less than 1.5 times the thickness of the guide rail (25) at the location of the screw connection, also measured in the direction of the longitudinal screw axis.
8. The elevator door guiding system (1) according to any one of the preceding claims, characterised in that each of the guide rails (25) is a preferably single-part bent sheet metal part and preferably all guide rails (25) are identical.
9. A guide rail (25) for an elevator door guiding system (1) according to any one of the preceding claims, which is configured as a bent sheet metal part and has a U-profile section (31) open in the downward direction, which in turn comprises a running surface of the guide rollers (7, 8) of a carriage (5, 6), wherein the guide rail (25) moreover has a secondary section (28) forming a running surface for the counter-rollers (12) of the aforementioned carriage (5, 6), characterised in that at least one leg of the U-profile section (31) includes an acute angle α with the secondary section (28).

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