EP2233042B1 - Chair with locking devices - Google Patents

Description

The invention relates to a chair with a support frame of a tubular profile, wherein the support frame has two spaced apart U-shaped frame sides, and at least one sheet-shaped or at least two rod-shaped cross members for connecting the two frame sides, and with a removably attached to the support frame one-piece seat shell made of a flexible, elastically deformable material, in particular plastic, which is integrally provided at its bottom and / or back with extending substantially perpendicular to the shell surface reinforcing webs, wherein the reinforcing webs fastening means for fixing the seat shell on the support frame, which at least partially as elastic latching means are executed, which latch automatically during assembly of the seat on the support frame.

More recently, the demands on the ergonomics of such chairs, especially for use as a student chair, as before in office chairs, the requirement in the foreground to allow mobility and elasticity of the chair a moving sitting with frequent change of seating position. For this type of sitting, the term "dynamic sitting" has come to be used. Especially for student chairs, due to the cost and robustness required, the requirements for dynamic seating must be met by the simplest and most secure mechanical means, and at the same time, the seat shells, which are often subject to more or less natural wear during this use, can be exchanged quickly and easily be.

Generally suitable for this chairs with a support frame of tubular frame and with an attached plastic elastic seat shell best because both the tubular frame and the seat shell with a suitable design have a high elasticity. Problem areas, however, are basically the connection points between the support frame and seat shell, in which the occurring by a resilient load of the support frame and by a resilient load on the seat pan material stresses must be transmitted via relatively rigid fastening devices and / or fastening means. In this case, caused by large jumps in stiffness material tension peaks, which can lead to cracks or breaks in the long term, especially on the plastic seat shells. The load is particularly large on seat panes with integrally formed backrests and can increase even more with increasing movement and dynamics when sitting.

At one of the DE 1 299 818 B known chair is the resilient plastic seat shell provided with wide locking lugs, which are integrally formed in Domen directly to the bottom of the seat. The seat can be easily assembled and the locking connections have due to the encompassing of the pipe profile in one direction and a certain elastic flexibility. At the same time, however, there are high voltage spikes due to the jumps in stiffness which lead to cracks and fatigue fractures, which is why such an embodiment is unsuitable for school operation for the other load directions and above all for a torsional loading of the seat shell.

To reduce the described loads, the DE 10 2006 043 006 A1 to carry out a seat shell as a double-shell plastic mold, which is much stiffer than a single-shell plastic mold. Overall, the production of such a hollow plastic seat shell but much more expensive and expensive than, for example, the production of a likewise suitable single-shell seat with reinforcing webs, as they are for. B. in the DE 2 402 644 A is disclosed. In these two known solutions, however, there is the problem that, although the seat is relatively stiff in itself, but the attachment points are located in weaker areas of the seat, resulting in the multi-dimensional deformation of the shell during dynamic sitting a greater tension in these areas Attachment shifted, which in turn can lead exactly to the previously described durability issues.

It is therefore better to also arrange the attachment points in stiffer areas of the seat and to intercept the increase in stiffness of the flexible areas of the seat there by suitable design of reinforcing webs. In the AT 304 808 B This is the possible deformation of the seat by a Stiffening of the shell reduced by means of a peripheral edge, which also fulfills the function of a reinforcing web. At the same time, the seat shell is laterally connected via this edge web by means of a flexibly movable latching connection with the tubular frame frame, so that the seat shell can be easily mounted. However, the seat can be just as easily disassembled by simply applying force to the shell. Overall, here reduces the mobility of the locking connection in this known solution, although the stresses in the joint because the vertical edge web can deform much by the large lateral play, but there is a high risk that in accordance with unquiet dynamic sitting and / or at Back and forth of these chairs, the locking connection due to the great deformability also solve again, that can unintentionally detent. This may cause damage to the chair or worse, jamming or injury to the user.

For the present invention, therefore, the task is to make a chair of the type described above so that even at high load by dynamic sitting unintentional unlocking the locking connection between the support frame and seat can be safely avoided. An additional screw is to be avoided and the manufacture, installation and dismantling of the chair should be correspondingly easier and cheaper. In addition, a danger that would result in forgetting a screw during assembly for use, to be counteracted.

The object is achieved by a chair of the type mentioned, which is characterized in that the support frame has stops which occurring during loading of the seat shell deformations of the latching means supporting vertical reinforcing webs in the region of the locking means opposite the locking movement to a lesser extent to limit a necessary for unlocking the locking means measure.

In the chair according to the invention an unwanted automatic unlatching, driven by a deformation of the latching means supporting vertical reinforcing web, do not occur, because the reinforcing web can not deform so far that the necessary path for unlocking the locking means is generated. This way can only by a deliberate manual operation of the locking means specially in the direction of Entrastens in a free space next to or in the attacks for the reinforcing web.

It is advantageous if at least one stop opposite to the latching movement is arranged near the respective latching means, because thereby the influence of the web movement remains low on the latching means and still the necessary movement path can be made possible by the latching means itself.

An even more favorable embodiment results when several stops are arranged opposite to the detent movement on both sides near the respective locking means, wherein the distance of the stops is greater than the width of the locking means and the locking means for unlocking intentionally manually in the distance space is movable.

Furthermore, it is also conceivable that a stop is arranged directly against the respective locking means against the latching movement, wherein the stopper then has a recess for the latching means and the latching means for unlocking intentionally manually in this recess is movable into it.

It when at least one stop against the latching movement on at least one fixed to the U-shaped frame sides connected crossbar is particularly advantageous.

A stop in the direction of the latching movement can also be formed by sections of the pipe profile itself.

For the advantageous manufacture and assembly of the chair according to the invention, it is particularly advantageous if the transverse traverse provided with stops is detachably arranged by means of tool support on the U-shaped frame sides. Thereby, the support frame can be easily adapted, for example, for the use of different seat shell designs.

There are various possibilities for the execution of a cross-beam provided with stops, which, however, all fulfill the object according to the invention. In one embodiment, the crosspiece can be designed rod-shaped with butterfly-like, the rod width changing approaches or indentations whose width approaches form at least one stop against the latching movement. In this case, the width approaches that make up the stop, even compared to the actual bar profile easily entangled or enforced in order to achieve a better investment on the vertical reinforcing web.

A particularly robust, but somewhat more elaborate design is the design of a provided with stops crossbeam as a hollow profile, U-profile or L-profile, of which forms at least one toward the bottom of the seat towards wall web extending at least one stop against the latching movement. A free space for the intended manual movement of the locking means for unlatching is then located next to or between the wall webs. A stop in the direction of the latching movement can also be formed by sections of the tubular frame itself below the seat. Conversely, it is also possible that a portion of the tubular frame below the seat shell forms a stop against the latching movement. The prerequisite for this is that the vertical reinforcement web or the latching means is at least as high as the pipe profile. Then namely, the diameter of the tube can form a continuous stop edge for the vertical reinforcing web against the latching movement and the free space in which the latching means for unlocking intentionally manually movable into, is then formed by the receding tube surface due to the circular arc. The latching means can be resiliently deflected for unlocking the pipe or partially around the pipe. This is possible because the stop against the locking direction then not close to the side next to, but near above the free space for unlocking the locking means is arranged. This is depending on the version, a direction of movement for unlocking the locking means towards the chair center or towards the chair edge out possible, so that a simple adaptation to the design of the seat is feasible.

For a further embodiment, it is also conceivable that the profile-shaped cross-beam has at least one slot through which a vertical reinforcing web of the seat is at least partially passed with little play, wherein at least one wall web of the profile, the limiting stops in and / or against the latching movement forms for the latching means supporting reinforcing webs, and that the profiled cross-beam counter to the latching movement has a free space for the latching means in which the latching means is intended to be moved manually for unlocking. The small but existing game provides doing so that the voltage peaks are kept low during load transfer, but at the same time the deformation is also kept small, so that no unwanted automatic unlatching of the locking means is possible.

Another, particularly simple and robust embodiment of the chair according to the invention is characterized in that a transverse reinforcing web of the seat shell is formed as a hook-shaped connection or elastic snap connection or molded thereto, which at least partially surrounds a crossbar, and further in the distance to locking means in the longitudinally extending reinforcing webs of the seat shell are arranged, which automatically engage in the assembly of the seat with corresponding locking openings of the support frame and / or a cross-beam. As a result, the assembly of the seat is much easier because initially the hook-shaped or snap connection is placed on a cross-beam, which can also be formed in a favorable manner as a tubular profile. Then, the seat is pivoted about this compound in the direction of the spaced latching means, which then can engage automatically, as they have a movement space in the direction of the latching movement and against the latching movement by a running of the locking head on the edge of the detent opening in the corresponding Free space or the recess are movable into it.

The above-described advantages of the chair according to the invention apply to all chairs with tubular frame, the support frame has two mutually spaced U-shaped frame sides, including for chairs in which the two legs of an inverted U each form a chair leg.

However, the solution according to the invention is particularly advantageous for chairs, which are characterized in that the U-shaped frame sides by a respective lower horizontal leg and a connected to this by a vertically or obliquely upwardly extending web leg, essentially determining the seat height upper support legs be formed. When the bridge legs extend approximately in extension of the backrest, such chairs are generally called console chairs. The U-shaped frame sides are quasi formed by a horizontal U, whose base leg is arranged in the region of the chair back. Often referred to as a C-frame, does not detract from the fact that these are also U-shaped frame sides within the meaning of the invention.

The same applies to chairs in which the web legs are arranged in the front area under the seat edge, ie on the opposite side to the backrest. Such chairs are generally referred to as cantilever chairs. Again, the frame sides are U-shaped in the context of the invention according to a lying on the side U with the base leg on the opposite side to the chair back of the chair.

The latter two frame designs are particularly suitable for dynamic sitting, since the tubular frame have a high own spring rate and are also produced by bending of cut-to-length pipe profiles in terms of strength and cost low.

If the tubular frames are designed in such a way that, like the two U-shaped frame sides, a crosspiece connecting them is also made of tubular material, then the two U-shaped frame sides and the crosspiece connecting them can even be produced from a single tube length by means of bending. which does not only affect the costs, but above all also has a favorable effect on the durability of these dynamically oscillating load-bearing support frames.

Further advantageous embodiments of the invention will become apparent from the dependent claims and possible combinations or variations thereof.

Figur 1

einen Stuhl in der Ausführung als Konsolenstuhl in montiertem Zu- stand in einer Seitenansicht,

Figur 2

den Stuhl aus Figur 1, mit einer Sitzschale bei der Montage,

Figur 3

den Stuhl aus Figur 1 in einer Ansicht schräg von links unten,

Figur 4

den Stuhl aus Figur 2 in einer Ansicht schräg von rechts unten,

Figur 5

in einem Ausschnitt schräg von rechts unten einen Verbindungsbe- reich zwischen Traggestell und Sitzschale mit Rastmitteln, deren Rastbewegung in Richtung der Stuhlaußenkante gerichtet ist,

Figur 6

in einem Ausschnitt schräg von rechts unten den Verbindungsbe- reich zwischen Traggestell und Sitzschale mit Rastmitteln, deren Rastbewegung in Richtung der Stuhlmitte gerichtet ist, und die

Figuren 7 - 11

verschiedene Ausführungsbeispiele von Quertraversen.

In the drawing, some embodiments are shown. The figures of the drawing show:

FIG. 1

a chair in the version as a console chair in the mounted state in a side view,

FIG. 2

the chair off FIG. 1 , with a seat shell during assembly,

FIG. 3

the chair off FIG. 1 in a view diagonally from the bottom left,

FIG. 4

the chair off FIG. 2 in a view diagonally from the bottom right,

FIG. 5

in a section obliquely from the bottom right a connection area between the support frame and the seat shell with latching means whose latching movement is directed towards the chair outer edge,

FIG. 6

in a section obliquely from the bottom right the Verbindungsbe- area between the support frame and seat with locking means whose locking movement is directed towards the chair center, and the

FIGS. 7-11

Various embodiments of crossbeams.

FIG. 1 shows a chair 1 with a support frame 2 of a tubular profile 21, wherein the support frame 2 has two mutually spaced U-shaped frame sides 3, 3 ', wherein the U-shaped frame sides 3, 3' by a respective lower horizontal leg 31th , 31 'and one with this by a vertically or obliquely upwardly extending web leg 32, 32' connected substantially the seat height determining upper support legs 33, 33 'are formed. In the illustration shown, the web legs 32, 32 'disposed below a backrest and a seat extends similar to a console on the support legs 33, 33' cantilevered forward, which is why such a chair form also referred to as a console chair. The U-shape of the frame sides 3, 3 'is here, as it were, on the side with the base limb of the U as web leg 32, 32'. Since this shape of the frame side also resembles the letter C, such a frame is sometimes referred to as a C-frame. Also conceivable for this purpose are not shown U-shaped frame sides, which are virtually on the other side, so have the base leg of the U as a web leg below the front seat. Such chairs are then generally referred to as cantilever, because the focus of the user has a greater distance from the web legs and the tube frame therefore relatively free springs or can swing. Also conceivable here are chairs, not shown, in which the frame sides are designed quasi as a head U standing, in which represent the two U-legs then two chair legs.

Just as this may be the case for the chair shapes just described, this is shown in FIG. 1 illustrated support frame 2 two rod-shaped cross members 4 for connecting the two frame sides 3, 3 ', of which the front cross-member from made of tubular material, in which case the two U-shaped frame sides 3, 3 'and the tubular cross-member 4 connecting these are made of a one-piece tubular profile 21 by means of bending.

On the support frame 2 is a one-piece seat shell 5 made of a flexible, elastically deformable material, in particular plastic, removably attached. The seat shell 5 is provided for selectively influencing its elasticity and deformability on its lower and / or rear side 53 in one piece with reinforcing webs 51 running essentially perpendicular to the shell surface. The reinforcing webs 51 have fastening means 6 for fastening the seat shell 5 on the support frame 2, which are designed in this embodiment in the rear region of the longitudinal reinforcing webs as elastic locking means 61 in the form of locking lugs 61, which in the assembly of the seat 5 on the support frame 2, or latch here in corresponding detent openings in the frame sides 3, 3 'connecting rear cross-beam 4 automatically.

How this is done in the assembly of the seat is in Fig. 2 shown. The front attachment means 6 of the seat shell 5 is executed on the front transverse vertical or oblique reinforcement web 52 on the underside 53 of the seat shell 5 in the form of a hook-shaped claw or snap connection 62 at least partially encompassing the front tubular cross member 4. When mounting the seat 5 on the support frame 2, the claw 62 is first placed on the front tubular cross-beam 4. Then, the seat 5 is pivoted about the front cross-beam 4 in the direction of the rear cross-beam 4 down, causing the locking means 61 engage automatically in the corresponding detent openings of the rear cross-beam. The longitudinal vertical reinforcing webs come with little play between the support legs 33, 33 'and the end faces of the wall webs 42 of the rear cross-beam 4 to lie.

In the Fig. 3 is this ready assembled state of the seat 5 to see the support frame 2 in a view obliquely from below. The underside 53 of the seat 5 lies on the support legs 33, 33 'of the U-shaped frame sides 3, 3', wherein the web legs 32, 32 ', the U-shaped connection to the horizontally resting on the floor stand legs 31, 31' produce , The at the bottom 53 of the seat 5 substantially obliquely perpendicular to perpendicularly extending reinforcing webs 51, 52 extend at stop surfaces close to the tubular support legs 33, 33 'and at least partially close to the transverse members 4, but without being firmly connected to these. The existing game and the corresponding mobility ensures the avoidance of larger stress peaks due to stiffness jumps. At the same time, the arrangement of the reinforcing webs 51, 52 corresponding to the arrangement of the support legs 33, 33 'and connecting them cross members 4, the same areas of seat shell 5 and support frame 2 reinforced or stiffened, whereby the elastic spring effects substantially in the adjacent areas be caught. This provides a relatively large transition of the forces between the seat 5 and the support frame 2, which leads to low material stresses. In the front region of the tubular cross-beam 4, the seat shell 5 is elastically held by the claw 62 arranged on the front transverse reinforcing web 52.

In FIG. 4 the seat 5 is shown lifted from the support frame 2 in order to better represent the details of the implementation of the vertical reinforcing web 51 between the rear cross-member 4 and the tubular support legs 33, 33 '. The circumferential line of a support leg 33 or 33 'pointing inwards toward the center of the chair fulfills the function of a stop 7 for limiting the deformation of the associated vertical reinforcement web 51. The stop 7 in the other direction of the deformation of the web is formed by the end edges of one or more wall webs 42 of the rear cross-member 4 formed, depending on the structural design of the cross-beam. Some embodiments of this are in FIG. 7 to FIG. 11 shown.

First of all, it is less important for a low-voltage absorption of the vertical reinforcing web 51 between the stops 7, which stop side forms the stop against the latching movement R and which forms the stop in the direction of the latching movement. This constructive determination of the direction of the latching movement depends solely on the arrangement of the latching means 61, shown here as a spring bar with a locking lug from. The latching lug of the latching means 61 requires a latching edge of a corresponding opening 63 in the direction of the latching movement. Contrary to the latching movement, the latching spring and the latching lug of the latching means 61 require a free space 71 in which the latching means 61 is intended to be manually moved in for unlatching. This space is close besides, between or under an associated stop 7, which limits the deformation movement of the vertical reinforcing web 51. Therefore, a possible deformation of the web 51 can not generate a necessary path for the unlocking E under any circumstances. This can only be achieved by intentional manual actuation of the locking means in the free space 71 inside.

From the desired direction of actuation E for unlatching it now depends on how the stops 7 and the free spaces 71 are to be designed and arranged. The position of the latching means 61 corresponding to the detent opening 63 and thus the design of the rear cross-beam are given by.

In the FIG. 5 is the arrangement of the rear cross-beam 4, the locking means 61, the stops 7 and the clearances 71 for an actuating direction E for the desired manual unlatching in the direction of the center of the seat 5 out, so represented by pressing the latching means 61 from the outside. In this embodiment, in each case a portion of the tubular support leg 33, 33 'forms the stop in the direction of the latching movement R and the end faces of the wall webs 41 of the rear cross-beam form the stops against the latching movement R for the respective vertical web 51. The necessary space 71 for the intentional manual unlatching in the direction E forms the space between the wall webs 42 and the wall space 42 adjacent to a free space.

In FIG. 6 is the arrangement of the components then for an operating direction E for the desired manual unlocking of the locking means 61 in the direction of the edge of the seat 5 out, so by pulling the locking means 61 from the outside, shown. In this embodiment, the end faces of the wall webs 42 of the rear cross-beam 4 form the stop in the direction of the latching movement R and a portion of the tubular support leg 33, 33 'forms the stop against the latching R. Since the latching means 61 for the intentional manual unlatching in the direction of E. Thus, to the pipe, yes, a corresponding space 71 required, either the pipe can be provided with a recess or indentation at the appropriate location, but this would mean an additional effort, or the locking means 61 can be performed on the vertical web 51 so high in that the latching lug is located in the upper region or above the tube profile 21. Then, for the desired manual unlatching E, the detent spring of the latching means 61 can be resiliently bent to the pipe or partially around the pipe. This is possible because the stop 7 opposite to the latching direction then not close to the side next to, but in the form of a surface line of the tube 21 near above a free space 71 is arranged, which is then formed by the receding relative to the web surface of the pipe profile.

In the FIGS. 7 to 11 are some proposals for a rod-shaped, the stops 7 supporting rear cross-beam 4 shown, with only the location and function of the important for the operations of ratcheting and Entrastens areas and functions to be discussed. As can be seen, a variety of crossbeams can be produced, for example, as butterfly-like sheet metal blanks or stampings. Leaving such a blank in a flat, rod-like basic shape as in FIG. 7 , the width approaches 41 may form the stops 7. A corresponding to the locking means latching opening 63 can be stamped with it. To improve the stop function, the width approaches 41 can also be entangled or punched during the punching process.

From a corresponding sheet metal blank can also be bent by bending U-shaped cross members, as in FIG. 8 , or L-shaped or angular crossbeams, as in FIG. 9 , easy to make. These crossbeams may have their stops 7 on the end faces of the one or two wall webs 42. At the support legs 33, 33 ', the crossbeams z. B. by welding or riveting unsolvable or z. B. be releasably secured by screws. A detachable design, as in FIG. 9 , Has the advantage that the support frames 2 can be adapted by a suitable selection of crossbeams 4 for different chairs during assembly or retrofitting of various seats 5.

Finally, the show FIGS. 10 and 11 Still embodiments in which the longitudinal vertical reinforcing webs are not received between the tubular support legs 33, 33 'and the cross-beam 4, but each in a slot 43 in the cross-beam 4, through each a vertical reinforcing web 51 of the seat 5 with little play at least partially passed, wherein at least one wall web 42 or width approach of the profile forms the limiting stops 7 in and / or against the latching movement R for the latching means 61 supporting reinforcing webs 51. In this case, the profile-shaped cross-beam 4 against the latching movement R a space 44 for the latching means 61, which is increased counter to the slot 43 and in which the latching means 61 intentionally manually movable for unlatching E.

LIST OF REFERENCE NUMBERS

character description 1 chair 2 supporting frame 21 tube profile 3, 3 ' U-shaped frame sides 31.31 ' stand leg 32, 32 ' web leg 33, 33 ' supporting leg 4 crossbeam 41 Travers approaches 42 Travers wall web 43 Travers slot 44 Travers clearance 5 seat 51 longitudinal vertical reinforcing webs 52 transverse reinforcing webs 53 Bottom of the seat 6 fastener 61 elastic locking means 62 hook-shaped connection 63 latching opening 7 attack 71 Distance space between stops 7 72 Recess in the stop 7 R Direction of the locking movement e Direction of the Entrastbewegung

Claims (14)

1. A chair (1) comprising a support frame (2) of a tube-shaped profile (21),
   wherein the support frame (2) encompasses two U-shaped frame sides (3, 3'), which are arranged at a distance from one another, as well as at least one laminar or at least two rod-shaped crossbars (4) for connecting the two frame sides (3, 3') and comprising a one-piece seat shell (5), which is made of a flexible, elastically deformable material, in particular plastic, which is fastened to the support frame (2) so as to be capable of being removed, which, on its lower and/or rear side, is provided in one piece with reinforcement bars (51), which run substantially vertically to the shell surface, wherein the reinforcement bars (51) encompass fastening means (6) for fastening the seat shell (5) to the support frame (2), which are at least partially embodied as elastic locking means (61), which automatically lock in place on the support frame (2) in response to the assembly of the seat shell (5),
   characterized in
   that the support frame (2) encompasses stops (7), which limit deformations of the vertical reinforcement bars (51) that support the locking means, which deformations appear in response to the stressing of the seat shell (5) in the area of the locking means (61) opposite to the locking movement (R) to a lower level than the level, which is necessary for unlocking (E) the locking means (61).
2. The chair according to claim 1, characterized in that at least one stop (7) is arranged opposite to the locking movement (R) close to the respective locking means (61).
3. The chair according to claim 1, characterized in that a plurality of stops (7) are arranged on both sides close to the respective locking means (61) opposite to the locking movement (R), wherein the space (71) between the stops (7) is larger than the width of the locking means (61) and the locking means (61) can purposely be moved manually into the space (71) for unlocking purposes (E).
4. The chair according to claim 1, characterized in that a stop (7) is arranged directly on the respective locking means (61) opposite to the locking movement (R), wherein the stop (7) encompasses a recess (72) for the locking means (61) and the locking means (61) can purposely be moved manually into the recess (72) for unlocking purposes (E).
5. The chair according to any one of claims 1 to 4, characterized in that at least one stop (7) is arranged opposite to the locking movement (R) on at least one crossbar (4), which is fixedly connected to the U-shaped frame sides (3, 3').
6. The chair according to claim 5, characterized in that at least one stop (7) in the direction of a locking movement (R) is formed by sections of the tube-shaped profile (21).
7. The chair according to claim 5, characterized in that the crossbars (4), which are provided with stops (7), are arranged on the U-shaped frame sides (3, 3') so as to be capable of being removed by means of tool support.
8. The chair according to any one of claims, 5 to 7, characterized in that the crossbar (4), which is provided with stops (7), is embodied in a rod-shaped manner comprising butterfly-like attachments (41) or notches, which change the rod width, and the width attachments (41) of which form at least the stop (7) opposite to the locking movement (R).
9. The chair according to any one of claims 5 to 7, characterized in that the crossbar (4), which is provided with stops (7), is embodied as a hollow profile, U-profile or L-profile, at least one wall bar (42) of which, which runs in the direction towards the bottom side (53) of the seat shell (5), forms at least one stop (7) opposite to the locking movement (R).
10. The chair according to claim 9, characterized in that the profile-shaped crossbar (4) encompasses at least one slit (43), through which a vertical reinforcement bar (51) of the seat shell (5) is in each case at least partially guided with a small play, wherein at least one wall bar (42) of the profile forms the limiting stops (7) in and/or opposite to the locking movement (R) for the reinforcement bars (51), which support the locking means (61), and in that the profile-shaped crossbar (4), opposite to the locking movement (R), encompasses a head space (44) for the locking means (61), into which the locking means (61) can purposely be moved manually for unlocking purposes (E).
11. The chair according to any one of the preceding claims, characterized in that a reinforcement bar (52) of the seat shell (5), which runs at right angles, is embodied or is integrally molded thereon as a hook-shaped connection (62) or as an elastic snap-in connection, which at least partially encompasses a crossbar (4), and in that locking means (61) are furthermore arranged at a distance thereto in the reinforcement bars (51) of the seat shell (5), which run longitudinally and which automatically lock in place with corresponding locking openings (63) of the support frame (2) and/or of a crossbar (4) in response to the assembly of the seat shell (5).
12. The chair according to any one of the preceding claims, characterized in that the U-shaped frame sides (3, 3') are formed in each case by a lower horizontal base journal (31, 31') and by an upper support journal (33, 33') connected thereto by means of a crosspiece journal (32, 32') running vertically or slanting upwards, which substantially determines the sitting level.
13. The chair according to claim 12, characterized in that the two U-shaped frame sides (3, 3') and a crossbar (4), which connects them, are made of tube-shaped material.
14. The chair according to claim 13, characterized in that the two U-shaped frame sides (3, 3') and a crossbar (4), which connects them, are made of a one-piece tube-shaped profile (21) by means of bending.

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