DE102013203906A1 - Method for producing a front wishbone and front wishbone - Google Patents

Abstract

The invention relates to a method for producing a wishbone for connecting a vehicle wheel to a vehicle, preferably as a front wishbone for connecting to a wheel carrier, a subframe and a body with at least the following steps: providing a semi-finished product made of sheet metal, at least regionally forming the semi-finished product into one Handlebar body (2), creating a bearing receptacle (11) on the semi-finished product or the handlebar body (2) for a bushing (12). It is proposed that two areas of the semi-finished product be formed into support sections (13, 14) to form the bearing receptacle (11), with an opening in each of the support sections (13, 13) to accommodate the bushing (12) before, during or after the bending. 14) is ordered. Furthermore, a wishbone for connecting a vehicle wheel to a vehicle, preferably as a front wishbone for connection to a wheel carrier, a subframe and a body, is shown, comprising a link body (2) with at least one bearing receptacle (11), which is used for the arrangement of a socket (12) is provided on the handlebar body (2). According to the invention, the bearing receptacle (11) has two spaced-apart support sections (13, 14), each of which has an opening, the support sections (13, 14) being oriented towards one another so that the bushing (12) through the openings is simultaneously in both Support sections (13, 14) can be arranged.

Description

The present invention relates to a method for producing a transverse link for connecting a vehicle wheel to a vehicle, in particular a motor vehicle, preferably as a front wishbone for connection to a wheel carrier, a subframe and a body and a wishbone for the connection of a vehicle wheel to a vehicle, in particular Motor vehicle preferably has a front wishbone for connection to a wheel carrier, a subframe and a body.

Wishbones form part of the suspension of a vehicle. As part of the suspension particular independent suspensions are constructed in the usual way from several links. In order to allow the compression and rebound of the vehicle wheel, the handlebars are rotatably mounted depending on the vehicle type at least on the vehicle body or on the chassis. The rotatability is reduced to an essentially vertical pivoting permitting rotation axis, so that the vehicle wheel is otherwise set horizontally with respect to the rest of the vehicle.

Depending on the design and installation position, a distinction is made between longitudinal, oblique and transverse links. Their respective orientation relates to the direction of travel of the vehicle, so that the wishbone extends substantially transversely to the direction of travel. The vehicle-mounted storage via at least one socket, which is usually designed as a composite bearing in the form of a rubber-metal bearing. The rubber component ensures sufficient decoupling and limited mobility of the handlebar against its storage.

Nowadays, wishbones are usually designed as a wishbone. Their handlebar bodies have predominantly a L- or sickle shape, wherein at one of its end portions a pivot bearing and at the opposite end portion a connection point for a ball joint or its direct arrangement is provided. Swivel bearing and ball joint are also supplemented by another bearing in the form of a socket, said sleeve, pivot bearing and ball joint form the vertices of a triangle to each other.

In the ball joint is usually a ball joint, via which the wishbone is coupled, for example, with a strut or steering knuckle of the suspension. The link body may be composed of, for example, aluminum or one or more sheets joined together. When using sheet metal this is preferably at least partially reshaped, in particular to increase its stability in addition to the individual shape adaptation.

Since the moving parts of the suspension are unsprung masses, efforts are made to reduce their weight as far as possible. As a result, the ride comfort can be increased and at the same time reduce the vehicle weight, which is becoming increasingly important, especially in view of the lowest possible fuel consumption.

A wishbone for the connection of a vehicle wheel to a vehicle, for example, from CN 201 665 139 U known. This comprises a handlebar body made of a deformed semi-finished sheet metal. At least one bearing receptacle for a bearing in the form of a bush is provided on the link body. The bush is aligned horizontally with respect to the typical mounting position of the control arm. When stock picking is a tube which is joined via a welded joint with the handlebar body.

A wishbone with a Y-shaped handlebar body made of solid material goes out of the CN 201 856 594 U out. In two of its legs openings are provided for receiving bushings end. The openings are arranged so that the longitudinal axes of the two bushings lie on one another. The bushes each comprise an inner tube and a surrounding elastic outer tube. Both inner tube and outer tube have a circumferential collar. The inner tube and the outer tube are manufactured separately. Due to the subsequent subsequent joining process, the inner tube is rotatably mounted in the elastic outer tube. In order to limit an axial displacement of the bushings in the openings, these are supported by the collar of the inner and outer tubes. For this purpose, the bushes are pressed in opposite directions in the openings of the control arm. In this way can be done via the inner tubes of the bushings and the handlebar, the movable connection of the suspension to the vehicle.

Against the background of the most cost-effective production of wishbones these are still preferably made of sheet metal. In particular, the creation of the bearing support by a pipe is an overhead, since this requires as a separate component additional manufacturing steps for fixing it to the handlebar body. Particular mention should be made of welding, with which the pipe must be attached. Welding is in itself very capital intensive due to the consumption of the necessary energy as well as the necessary welding machines. Due to the inevitable heat input into the Base material, ie in the wishbone can also adversely affect the material properties with respect to the required strength properties.

The invention is therefore based on the object, a method for producing a control arm for the connection of a vehicle to a vehicle, in particular motor vehicle, preferably a method for producing a front wishbone show, with a faster and more cost-effective production for the wishbone is possible. Furthermore, a wishbone, preferably a front wishbone for the same purpose will be shown, which in addition to its fast and inexpensive manufacturability has a lower weight. This is to be achieved in terms of the method on the one hand, that both less tools and less material must be used to produce the control arm and on the other hand, the tools required can be used even more intense.

The procedural part of this object is achieved by a method having the features of claim 1. Furthermore, the objective part of the problem is solved with the features of claim 7. Further, particularly advantageous embodiments of the invention disclose the respective subclaims.

It should be noted that the features listed individually in the following description can be combined with one another in any technically meaningful manner and show further embodiments of the invention. The description additionally characterizes and specifies the invention, in particular in connection with the figures.

According to the invention, a method for producing a transverse link for connecting a vehicle wheel to a vehicle, in particular a motor vehicle, has at least the following steps:
Providing a semifinished product of sheet metal,
At least partially reshaping of the semifinished product to form a handlebar body,
Creating a bearing receptacle on the semifinished product or the handlebar body for a socket.

To form the bearing receiving two areas of the semifinished product are converted into support sections. For receiving the socket, an opening in the support sections is arranged before, during or after the turn.

The inventive method preferably for producing a front wishbone for connection to a wheel, a subframe and a body is characterized by the fact that this allows less economical than usual manufacturing steps manufacturing a wishbone. This is due in particular to the proposed measure for creating the bearing seat, which requires no additional arrangement of a pipe to be connected to the handlebar body more. In particular, eliminates the previously necessary welding, so that changes in material properties are not to be feared due to the attributable heat input. The receptacle for the socket is advantageously made in one piece with the wishbone.

Thus, the already existing sheet material can be used in the form of the semifinished product or the already converted from this link body to create the necessary bearing receptacle for the arrangement of the socket. In other words, the bearing receptacle is created in that at least two regions of the semifinished product or the steering body are reshaped or simply bent so that they are converted into support sections. The openings to be arranged in it are used to accommodate the socket.

It is provided that the sleeve extends in its connected to the link body state between the two support portions and also received in their respective openings, in particular is stored. Preferably, the openings and the bush are matched to one another so that the bush is pressed into the openings of the support sections. As a result, a tight fit is made possible, which does not require any additional measures to secure the socket in the bearing mount thus created.

Particularly preferably, the support sections are oriented in their orientation to the same side of the handlebar body out. In this case, the support sections which are preferably spaced apart from one another in their origin on the link body can also be aligned skewed relative to one another. Windschief means that the support sections do not intersect or touch and enclose an angle between them in their theoretical extension. Of course, it is also conceivable that the support sections touch each other in regions and also include an angle between them. The respective angle can be set between the two side surfaces of the support sections or between the edges bounding the side surfaces of the support sections. Furthermore, the support sections may also extend curved or twisted away from their origin, wherein these are preferably formed in a straight line.

The socket to be arranged in the bearing receptacle can at least one of its end portions have a circumferential or only partially arranged thickening. The thickening serves to support the bushing against a region of the support sections around the opening. In this way, the sleeve is fixed in at least one of its longitudinal directions in their displaceability relative to the bearing support. Following the structure of conventional composite bearing, said thickening may be formed on the inner tube and / or on the outer jacket surrounding it made of an elastic material.

If the thickening is formed at both end regions of the bushing, this must be able to be elastically displaced at at least one end region. With the elastically displaceable thickening ahead, the bushing can then be pressed into the openings of the support sections. As a result of the thickenings which are supported against the sides of the two support sections facing away from one another, the bush is fixed or at least limited in its displacement in one of its longitudinal directions.

The determination of the socket in the bearing receptacle can be made positive and / or non-positive. Also conceivable is a cohesive connection, wherein the socket is glued or vulcanized, for example, in the bearing receptacle.

In an advantageous development, the areas in question of the semifinished product or the steering body can be reshaped such that the support sections are aligned parallel to each other. Particularly preferably, the support sections and their openings are aligned and arranged so that the openings are aligned.

The advantage of this arrangement can be seen in the fact that the sleeve is used transversely and thus not tilted relative to the support portions in the openings with respect to their longitudinal direction.

It is envisaged that the deformation of the areas to the support portions can be carried out simultaneously with the deformation of the semifinished product to the handlebar body. In this way, the handlebar body and the bearing seat can be formed in an economical manner within a single forming process. Alternatively, the formation of the bearing receptacle before or after the deformation of the semifinished product to the handlebar body would be conceivable, if the individual design requires it.

As an advantageous development of at least one of the openings is formed to form a collar as a passage. For this purpose, the semifinished product may already have the openings, of which at least one obtains a collar, for example, in connection with the preparation of the bearing seat by forming.

Of course, the arrangement of the collar can also be made before or after the deformation of the semifinished product and before or after the formation of the bearing support. Alternatively, the introduction of the openings with simultaneous formation of the collar is conceivable, which can also be done before, during or after the deformation of the semifinished product to the handlebar body.

With regard to the collar, it is envisaged that it can circumscribe at least one of the openings. In contrast, the collar can also be limited to only one or more partial areas, so that the respective opening is at least partially enclosed by the collar.

Due to the arrangement of the collar, an individually adaptable and sufficiently strong contact surface is created between at least one of the support sections and the bush. Since the forces to be introduced by the bushing via the support sections into the link body are transmitted via the surface provided by the collar, the stresses occurring in this connection are reduced. Overall, this allows a firm and stable fit of the bushing within the bearing receptacle thus created.

Particularly preferably, both openings are formed as a passage that the two collar of the support sections are aligned in their extension to each other, ie with their free end faces oriented towards each other. Due to the arrangement of the collar at both openings of the bearing mount the socket to be used is supported on both support portions within the resulting contact surfaces against the collar. This results in a solid and stable fit of the socket.

Due to the orientation of the collar to each other as narrow as possible to build bearing mount is created, which despite appropriate contact surfaces on the collar has no beyond the opposite outer sides of the two support sections extension. In addition to the resulting advantage of the smallest possible dimensions, the design of the openings is also facilitated as a passage, since their introduction can be made in particular during or after the forming of the semifinished product without any obstacles to the tools from opposite sides.

In a further development of the concept of the invention, the semifinished product can be reshaped edge-side to the link body at least partially peripherally bounding side walls, wherein the support sections are then formed from two immediately opposite end portions of the side walls. In other words, that will Semi-finished product hereby angled in regions at its edges, wherein the thus angled edge regions initially form the side walls of the handlebar body. Two immediately opposite end portions of the side walls form the required support sections of the bearing receiver.

Preferably, said end regions of the side walls are configured such that they extend beyond the planar dimensions of the link body, which are defined at least partially by the side walls. Accordingly, serving as support sections end portions of the side walls may extend beyond the handlebar body such that they have no U-shaped cross-section in connection with the rest of the handlebar body, but rather form the sleeve receiving, projecting cheeks. Due to the seamless transition of the support sections thus formed in the side walls with a minimum of material auskommende and thus easy and sufficient viable design of the bearing support is possible.

The previously presented method according to the invention enables the faster and in particular less expensive production for the production of a control arm, which serves to connect a vehicle wheel to a vehicle, wherein the wishbone is preferably designed as a front wishbone for connection to a wheel, a subframe and a body.

In the course of an inventive wishbone is shown below, which can serve for the connection of a vehicle wheel to a vehicle, wherein preferably a front wishbone for connection to a wheel, a subframe and a body is shown.

The wishbone invention comprises a handlebar body with at least one bearing receptacle, which is provided for the arrangement of a bushing on the handlebar body. According to the invention, the bearing receptacle on two spaced support sections, which each have an opening. The support sections are oriented to each other so that the socket can be arranged through the openings at the same time in both support sections.

The embodiment according to the invention, in particular the bearing support a seen lighter in weight is provided wishbone, which does not require additional components for receiving a socket. Since the bearing receptacle includes two support sections which are preferably spaced apart from one another, it does not have a cross-section that is generally closed on the circumference, as is the case with the arrangement of a pipe customary in the prior art.

The sleeve having a metallic inner tube in the usual way is supported inside the bearing receptacle in such a way that it is arranged at its end regions within the two openings. Thus, in particular, the inner tube extends from the one support portion to the other support portion, whereby a sufficiently viable bearing of the bush takes place on the bearing body.

In an advantageous embodiment, the two support sections of the bearing receptacle form a material integral part of the handlebar body. Even if the support sections can be joined as separate components with the link body, these are thus formed in an advantageous manner by forming the underlying the steering body material.

In a development, the two support sections can preferably be aligned parallel to one another, their openings being aligned with one another. In this way, a clear orientation of the bushing within the bearing receptacle is made possible without having to fear any tilting of the bush relative to the two support sections.

As a preferred embodiment, at least one of the openings is designed as a passage with a collar. Due to the arrangement of the collar, a larger contact surface is created than the inner edge otherwise limiting the opening. The forces to be transmitted from the bushing are distributed over said larger contact surface, which can reduce the occurring stresses and in particular the shear and shear stresses.

This is advantageous in that the socket is formed in the usual way as a composite bearing in the form of a rubber-metal bearing, wherein the sleeve comes into contact via its elastic portion with the bearing receptacle. As a result, the properties of the mostly made of rubber elastic portion can be adjusted to the necessary decoupling, without this sometimes adversely affecting increase in strength due to the burden of only a small contact surface.

An advantageous development of the invention provides that the link body is limited by this at least partially circumferential side walls. Said side walls may preferably be formed from angled edge regions of the material underlying the handlebar body. The support sections are formed in an advantageous manner from two immediately opposite end portions of these side walls. In this way, the already achieved by bending the sidewalls strength and alignment used without additional measures for the design of the support sections.

Further advantageous details and effects of the invention are explained in more detail below with reference to an embodiment shown in the figures. Show it:

1 a perspective view of a transverse link with a bushing having integrally formed material integrally bearing receptacle,

2 an enlarged perspective view of the bearing seat of the control arm 1 with the jack, and

3 the perspective view of the bearing support of the control arm

2 without the bush that can be arranged in it.

In the different figures, the same parts are always provided with the same reference numerals, so that these are usually described only once.

In 1 is a perspective view of a control arm 1 shown. The wishbone 1 includes a handlebar body 2 from a formed semi-finished sheet metal. The wishbone 1 is present and exemplified as a front wishbone, wherein the handlebar body 2 has a L or sickle shape.

With reference to the representation of the handlebar body 2 in 1 this points to a right end area 3 a pivot bearing 4 on. The pivot bearing 4 is opposite a plane in which the handlebar body 2 extends, oriented substantially vertically. Furthermore, at a right end area 3 opposite and in 1 left end area shown 5 a connection point 6 provided on which a ball joint receptacle 7 with a ball joint received therein 8th is arranged.

The ball joint socket 7 is about a total of three by the connection point 6 through in the ball joint socket 7 arranged fasteners 9 with the handlebar body 2 connected. In the present case are the fasteners 9 formed by riveting, so that the ball joint socket 7 insoluble with the connection point 6 of the control arm 1 connected is.

The handlebar body 2 has one between its end regions 3 . 5 located extension 10 on which at its free end a bearing receiver 11 has. The camp recording 11 and the extension 10 are present as a unitary integral part of the handlebar body 2 educated. The extension 10 is part of the bearing receiver 11 to watch. In the warehouse 11 is a jack 12 arranged, which is substantially parallel to the plane in which the handlebar body 2 extends, extends. In this arrangement, the cylindrically shaped sleeve 12 with its longitudinal direction on the pivot bearing 4 aligned. Here is the socket 12 through the extension 10 far enough from the rest of the handlebar body 2 spaced to allow free accessibility.

The socket 12 , the pivot bearing 4 and the ball joint 8th are the cornerstones of a triangle. In this arrangement, the socket serve 12 and the pivot bearing 4 the articulated connection of the wishbone 1 to an in 1 Not shown vehicle body of a vehicle, also not shown, in particular motor vehicle. In contrast, the ball joint serves 8th the articulated coupling of a vehicle wheel, also not shown, so that this on the cross member 1 can be connected to the vehicle body of the vehicle.

In 2 is an enlarged perspective view of the bearing receiver 11 with the socket 12 of in 1 shown wishbone 1 shown. As can be seen, the bearing receiver 11 two support sections 13 . 14 on. The supporting sections 13 . 14 are in their planar extension substantially perpendicular to the plane in which the handlebar body 2 extends, aligned. The supporting sections 13 . 14 are already at their origin on the handlebar body 2 spaced apart. They form a material integral integral part of the handlebar body 2 ,

The two support sections 13 . 14 are aligned parallel to each other, with the socket 12 with respect to their longitudinal direction substantially transverse to opposite and opposite sides 15 . 16 the support sections 13 . 14 extends. The socket 12 is presently carried out in the usual way as a composite bearing in the form of a rubber-metal bearing. At both ends, the socket has 12 thickening 17 . 18 on, over which the socket 12 at least partially against the pages 15 . 16 the support sections 13 . 14 supported.

As already in 1 visible and in 2 clarifies, is the handlebar body 2 by this at least partially circumferential side walls 19 . 20 bounded on the edge. Through the side walls 19 . 20 receives the handlebar body 2 its spatial configuration and in particular its required strength, since this is an increase in the moment of resistance of the handlebar body made of sheet metal 2 cause. In this context, the carrying portions 13 . 14 advantageously from two immediately opposite end portions 21 . 22 of these side walls 19 . 20 educated.

As can be seen, said end regions extend 21 . 22 the side walls 19 . 20 over the remaining handlebar body 2 and in particular over the U-shaped cross-section of the extension 10 out so that they form two spaced apart cheeks.

In 3 is the perspective view of the bearing receiver 11 of the control arm 1 out 2 again without the bush can be arranged in it 12 shown. As can be seen in this illustration, have the support sections 13 . 14 one opening each 23 . 24 , The openings 23 . 24 serve to accommodate the socket, not shown here 12 from the 1 and 2 , The supporting sections 12 . 13 are oriented to each other so that the socket not shown here 12 through the openings 23 . 24 through at the same time in both support sections 12 . 13 can be arranged. In the present case are the support sections 12 . 13 and the openings 23 . 24 arranged so that the openings 23 . 24 aligned with each other. In other words, these can with respect to the planar configuration of the support sections 13 . 14 be arranged congruently.

In the present embodiment, both openings 23 . 24 designed as a draft, so that these each have a collar 25 . 26 exhibit. The respective collar 25 . 26 is designed so that this the respective opening 23 . 24 circumscribed limited. To a narrow as possible building stock 11 to create, are the two collars 25 . 26 oriented so that they face each other, so are oriented towards each other. In other words, the collars 25 . 26 on the mutually facing sides of the directly opposite support sections 12 . 13 arranged.

• – Bereitstellen eines Halbzeugs aus Blech,
• – Zumindest bereichsweises Umformen des Halbzeugs zu dem in 1 dargestellten Lenkerkörper 2,
• – Erstellen der Lageraufnahme 11 an dem Halbzeug oder dem Lenkerkörper 2 für die Buchse 12,

wobei zur Ausbildung der Lageraufnahme 11 zwei Bereiche des Halbzeug oder des bereits erstellten Lenkerkörpers 2 zu den Tragabschnitten 13, 14 umgeformt werden. Für die Aufnahme der Buchse 12 wird vor, während oder nach dem Umformen je eine der Öffnungen 23, 24 in den beiden Tragabschnitten 13, 14 angeordnet.In the 1 to 3 is the result of the control arm produced by the method according to the invention 1 which is obtainable after applying the following method steps:

• Providing a semifinished product of sheet metal,
• - At least partially reshaping of the semifinished product to the in 1 illustrated handlebar body 2 .
• - Create the warehouse 11 on the semifinished product or the handlebar body 2 for the socket 12 .

being used to form the bearing receiver 11 Two areas of the semi-finished or already created handlebar body 2 to the support sections 13 . 14 be transformed. For receiving the socket 12 is before, during or after forming ever one of the openings 23 . 24 in the two support sections 13 . 14 arranged.

The above-described inventive method for producing a control arm for the connection of a vehicle wheel to a vehicle, in particular a motor vehicle, is not limited to the embodiment disclosed herein, but also includes similar acting further embodiments.

In a preferred embodiment, the inventive method for producing a transverse link for the connection of a vehicle wheel to a vehicle, in particular a motor vehicle, is used. In a further preferred embodiment, a front wishbone is produced which can be connected to a wheel carrier, to a subframe and to a body.

LIST OF REFERENCE NUMBERS

1

wishbone

2

arm body

3

end

4

pivot bearing

5

end

6

connecting point

7

Ball joint socket

8th

Traggelenk

9

fastener

10

extension

11

bearing seat

12

Rifle

13

supporting section

14

supporting section

15

page

16

page

17

thickening

18

thickening

19

Side wall

20

Side wall

21

end

22

end

23

opening

24

opening

25

collar

26

collar

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• CN 201665139 U [0007]
• CN 201856594 U [0008]

Claims (10)

Method for producing a transverse link ( 1 ) for the connection of a vehicle wheel to a vehicle, preferably as a front wishbone for connection to a wheel, a subframe and a body with at least the following steps: providing a semifinished product made of sheet metal, at least partially reshaping the semifinished product to a handlebar body ( 2 ), Creating a warehouse record ( 11 ) on the semifinished product or the steering body ( 2 ) for a socket ( 12 ), Forming two areas of the semifinished product into support sections ( 13 . 14 ), so that the bearing ( 11 ) is formed, wherein for receiving the socket ( 12 ) before, during or after forming an opening ( 23 . 24 ) in the support sections ( 13 . 14 ) is arranged. A method according to claim 1, characterized in that the two areas are formed such that the support sections ( 13 . 14 ) are aligned parallel to each other and the openings ( 23 . 24 ) are aligned with each other. A method according to claim 1 or 2, characterized in that the deformation of the areas to the support sections ( 13 . 14 ) simultaneously with the deformation of the semi-finished product to the steering body ( 2 ) he follows. Method according to one of claims 1 to 3, characterized in that at least one of the openings ( 23 . 24 ) forming a collar ( 25 . 26 ) is designed as a passage. Method according to one of claims 1 to 4, characterized in that the semi-finished product at the edge to the handlebar body ( 2 ) at least partially peripherally bounding side walls ( 19 . 20 ) is formed, wherein the support sections ( 13 . 14 ) of two immediately opposite end regions ( 21 . 22 ) of the side walls ( 19 . 20 ) are formed. Wishbone ( 1 ) produced in particular according to a method of the preceding claims, for the connection of a vehicle wheel to a vehicle, preferably a front control arm for connection to a wheel carrier, a subframe and a body comprising a handlebar body ( 2 ) with at least one bearing receiver ( 11 ), which for the arrangement of a socket ( 12 ) on the handlebar body ( 2 ), characterized in that the bearing receptacle ( 11 ) two spaced support sections ( 13 . 14 ), each having an opening ( 23 . 24 ), wherein the support sections ( 13 . 14 ) are oriented to one another such that the bushing ( 12 ) through the openings ( 23 . 24 ) through at the same time in both support sections ( 13 . 14 ) can be arranged. Wishbone according to claim 6, characterized in that the support sections ( 13 . 14 ) integral parts of the handlebar body ( 2 ) are. Wishbone according to claim 6 or 7, characterized in that the two support sections ( 13 . 14 ) are aligned parallel to each other, wherein the openings ( 23 . 24 ) are aligned with each other. Wishbone according to one of claims 6 to 8, characterized in that at least one of the openings ( 23 . 24 ) as a passage with a collar ( 25 . 26 ), wherein the collars ( 25 . 26 ) are oriented towards one another with their free end faces. Wishbone according to one of claims 6 to 9, characterized in that the link body ( 2 ) by these at least partially circumferential side walls ( 19 . 20 ) is limited, wherein the support sections ( 13 . 14 ) of two immediately opposite end regions ( 21 . 22 ) of the side walls ( 19 . 20 ) are formed.

Images