DEVICE FOR A SEATING FURNITURE

Abstract

A device for an item of seating furniture, in particular a pivot mechanism, and an item of seating furniture having such a device, are provided. In order to simplify the construction of items of seating furniture, the use of a deformation element which is integral, that is to say integrated into the device, which is deformable, which is composed preferably of a plastics material, and which serves as an energy storage member, is proposed.

Claims

1-14. (canceled)

15. A device for an item of seating furniture, the device comprising: a base support, a seat support and a backrest support; a rearward pivoting of said backrest support inducing a following movement of said seat support; at least one elastically deformable element serving as an energy storage member, said at least one elastically deformable element being integrated in single-piece form into the device; said at least one elastically deformable element connecting said seat support to said base support as a single-piece seat support-base support combination, permitting said seat support to move relative to said base support.

16. The device according to claim 15, wherein said at least one elastically deformable element is deformable upon an exertion of a load on the device exerted to cause a movement of the device.

17. The device according to claim 15, wherein said at least one elastically deformable element is composed of a plastics material.

18. The device according to claim 15, wherein said at least one elastically deformable element has multiple members or structure planes acting in parallel and having stiffnesses dependent on a direction of an action of a force acting thereon, causing said at least one elastically deformable element to deform differently in a manner dependent on the direction of the action of the force.

19. The device according to claim 15, which further comprises a multi-jointed coupling gear, one elastically deformable element being formed as an integral constituent part of said coupling gear, as a coupler or as part of a coupler.

20. The device according to claim 19, wherein said at least one elastically deformable element has a multiplicity of virtual centers of rotation providing an infinite joint gear for the device.

21. The device according to claim 15, wherein the device provides a pivoting movement not being implementable without a deformability of said at least one elastically deformable element.

22. The device according to claim 21, wherein said backrest support pivots through a pivot angle greater than 5° during the pivoting movement.

23. The device according to claim 15, wherein said at least one elastically deformable element is the only energy-storing structural part of the device.

24. The device according to claim 15, which further comprises a film joint connecting said backrest support and said seat support to one another in a single-piece form to allow the following movement of said seat support during a rearward pivoting of said backrest support.

25. The device according to claim 24, wherein said film joint has at least two film joint elements having mutually different spatial positions.

26. The device according to claim 15, wherein the device is a single-piece assembly including said backrest support, said seat support and said base support.

27. The device according to claim 26, wherein said single-piece assembly has characteristics of having been produced by a single filling of a single injection molding tool.

28. An item of seating furniture or an office chair, comprising a device according to claim 15.

29. The device according to claim 15, wherein the device is a pivot mechanism.

Description

[0050] Several exemplary embodiments of the invention will be discussed in more detail below on the basis of the drawings, in which:

[0051] FIG. 1 shows a pivot mechanism according to the prior art with four centers of rotation,

[0052] FIG. 2 shows a first pivot mechanism with a first embodiment of the deformation element in a basic position (side view),

[0053] FIG. 3 shows the first pivot mechanism in the basic position (view from below),

[0054] FIG. 4 shows the first pivot mechanism in a rearwardly pivoted position (side view),

[0055] FIG. 5 shows the first pivot mechanism in a rearwardly pivoted position (view from below),

[0056] FIG. 6 shows a second embodiment of a deformation element of a pivot mechanism in the non-deformed state,

[0057] FIG. 7 shows a third embodiment of a deformation element in the non-deformed state,

[0058] FIG. 8 shows the deformation element as per FIG. 7 in the deformed state,

[0059] FIG. 9 shows a fourth embodiment of a deformation element of a pivot mechanism in the second load situation,

[0060] FIG. 10 shows the deformation element of the pivot mechanism in the first load situation,

[0061] FIG. 11 shows a second pivot mechanism in the basic position (side view),

[0062] FIG. 12 shows the second pivot mechanism in the basic position (view from below),

[0063] FIG. 13 shows a third pivot mechanism in the disassembled state (side view),

[0064] FIG. 14 shows the third pivot mechanism in the assembled state in the basic position (side view),

[0065] FIG. 15 shows a detail of the third pivot mechanism in the rearwardly pivoted position (side view),

[0066] FIG. 16 shows a variant of the third pivot mechanism with modified film joint (side view),

[0067] FIG. 17 shows the variant of the third pivot mechanism from FIG. 16 (view from above).

[0068] In all of the figures, the invention is shown not true to scale and merely schematically and only with its main constituent parts. Here, identical reference designations correspond to elements of identical or similar function.

[0069] “At the front” or “front” means here that a structural part is arranged at the front in a seat longitudinal direction or relates to a structural part which extends in the direction of the front seat edge or which points in said direction, whereas “at the rear” or “rear” means that a component is arranged at the rear in the seat longitudinal direction or relates to a structural part which extends in the direction of the backrest or of the backrest support or of the rear seat edge or which points in said direction. The expressions “at the top” or “top” or “higher” and “at the bottom” or “bottom” or “lower” relate to the intended state of use of the office chair or of the office chair mechanism.

[0070] In FIG. 1, in order to illustrate the pivoting principle, a pivot mechanism generally known from the prior art is shown in highly simplified form. This is a synchronous mechanism 139, in which the three main components of the mechanism, specifically base support 1, seat support 3 and backrest support 4 are coupled to one another by way of rotary joints, such that a pivoting movement of the backrest support 4 rearward induces a synchronous following movement of the seat support 3, whereas the base support 1 remains positionally fixed and immovable. The backrest support 4, with its articulation to the base support 1, on the one hand, and to the rear region of the seat support 3, on the other hand, forms a rear coupling element 140 which is integrated into the backrest support 4, whereas a separate, front coupling element 141 connects the base support 1 to the front region of the seat support 3. In this way, four centers of rotation are created, realized by four rotary joints, wherein each rotary joint is assigned a transverse axis. These are the first rotary joint 142 for the connection of the base support 1 to the rear coupling element 140, the second rotary joint 143 for the connection of the rear coupling element 140 to the seat support 3, the third rotary joint 144 for the connection of the base support 1 to the front coupling element 141, and the fourth rotary joint 145 for the connection of the front coupling element 141 to the seat support 3.

[0071] According to the invention, it is now possible in principle for all of the real centers of rotation realized by rotary joints 142, 143, 144, 145 to be replaced by virtual centers of rotation that are provided by one or more deformation elements according to the invention. In the case of the four-jointed coupler depicted by way of example in FIG. 1, it is for example possible for the separate, front coupling element 141 to be omitted and for the function of one or more coupling joints 142, 143, 144, 145 to be realized by means of structural parts or mechanism components equipped according to the invention with deformation elements, such as for example the base support 1. Correspondingly, the invention is also applicable to mechanisms of other construction, in particular to mechanisms with a different number of coupling joints. Here, the real centers of rotation may be replaced not only by the virtual centers of rotation according to the invention. With corresponding design of the mechanism, it is possible, by means of the enhanced deformability of individual mechanism components, for the number of required centers of rotation to also be reduced, whereby a simplified construction of the mechanism is possible. On the other hand, a considerable increase in the number of centers of rotation is also possible, specifically in the form of virtual centers of rotation, with a simultaneous decrease in the complexity of the mechanism construction.

[0072] Referring to FIGS. 2 to 5, a description will firstly be given of a synchronous mechanism 10 in the case of which the third rotary joint 144 is replaced by a deformation element according to the invention.

[0073] The mechanism 10 has a base support 1 which is placed by means of a cone receptacle 2 onto the upper end of a chair post 20 (see FIG. 2). Furthermore, the synchronous mechanism 10 comprises a substantially frame-like seat support 3 and a backrest support 4 which is fork-shaped in plan view, the webs 5 of which are arranged to both sides of the base support 1.

[0074] The seat support 3 is provided for receiving, or for the mounting of, a seat surface, which may be padded. The assembly process is performed with the aid of fastening elements (not illustrated in any more detail) in the conventional manner. Attached to the backrest support 4 is a backrest (not illustrated in any more detail) which, in modern office chairs, is height-adjustable. The backrest may also be connected in single-piece form to the backrest support 4.

[0075] The entire synchronous mechanism 10 is of mirror-symmetrical construction with respect to its central longitudinal plane, as regards the actual kinematics. In this respect, in the following description of this and further exemplary embodiments of the invention, it is always to be assumed that structural elements of the actual pivot mechanism are present in pairwise form on both sides.

[0076] FIGS. 2 and 3 show the basic position of the synchronous mechanism 10, in which the seat support 3 assumes a substantially horizontal position. FIGS. 4 and 5 show the synchronous mechanism 10 in a position of the backrest support 4 in which it has been pivoted rearward to a maximum extent.

[0077] The backrest support 4 which is pivotable in a pivoting direction 7 is, with its web 5 which extends in the direction of the front region 17 of the mechanism 10, articulatedly connected directly to the base support 1, with the formation of a first transverse axis 11, by means of a first rotary joint 21, wherein said transverse axis defines the main pivot axis 11 of the synchronous mechanism 10. The main pivot axis 11 lies in this case behind the cone receptacle 2 as viewed in the seat longitudinal direction 14.

[0078] In the rear region 16 of the mechanism 10 as viewed in the seat longitudinal direction 14, the backrest support 4 is, by means of an upwardly extending driver 6 of the web 5, simultaneously connected by means of a second rotary joint 22 to the rear region 25 of the seat support 3. Here, the main pivot axis 11 is, as viewed in the seat longitudinal direction 14, arranged behind the transverse axis 12 formed by the second rotary joint 22. A pivoting of the backrest support 4 out of the basic position into a rearwardly pivoted position is associated with a raising movement of the rear region 25 of the seat support 3.

[0079] In the front region 17 of the mechanism, the front region 18 of the base support 1 is directly articulatedly connected to the front region 24 of the seat support 3 by means of a third rotary joint 23, with the formation of a third transverse axis 13. The relative movement of seat support 3 and backrest support 4 with respect to one another is determined substantially by the position of the three joint axes 11, 12, 13 with respect to one another.

[0080] The backrest support 4 is directly connected to the seat support 3 only at one point, specifically by means of the transverse axis 12. Furthermore, the base support 1 is directly connected to the seat support 3 only at one point, specifically by means of the transverse axis 13. There is only a single direct connection of the backrest support 4 to the base support 1, specifically by means of the main pivot axis 11.

[0081] In the situation described by way of example on the basis of FIGS. 2 to 5, a part of the base support 1, specifically a deformation element 8 which is integrated into the base support 1 and which forms a longitudinal section of the base support 1, is elastically deformable, as discussed in detail further below. The deformation element 8 extends, so as to follow the extent of the base support 1, in the seat longitudinal direction 14.

[0082] The deformation element 8 in the form of the deformable part of the base support 1 serves simultaneously as a storage member integrated into the base support 1. The deformation element 8 thus not only defines the resetting force for the backrest support 4 but thus also serves for establishing the pivoting resistance of the backrest support 4.

[0083] The storage member 8 simultaneously serves as resetting element and, for this reason, is formed and arranged so as to be subjected to an exertion of load during a pivoting of the backrest support 4. Thus, a pivoting of the backrest support 4 always takes place counter to the spring force of the storage member 8, and the storage member 8 serves for resetting the backrest support 4 from a tilted position into its initial position.

[0084] By means of the described pivot mechanism, it is ensured that the backrest support 4 with the backrest can be pivoted rearward and downward in the pivoting direction 7 about the main pivot axis 11. Here, the backrest support 4 is pivoted through a pivot angle 9 of greater than 5°. Owing to the articulation of the seat support 3 on the backrest support 4, the seat support 3 is in this case likewise driven along rearwardly. At the same time, the pivoting movement of the backrest support 4 induces a raising movement of the rear region 25 of the seat support 3. At the same time, the front region 24 of the seat support 3 is raised. The base support 1 remains static during the pivoting movement of the backrest support 4.

[0085] The deformation element 8 will be described in more detail below.

[0086] The resistance of a body to elastic deformation by a force or a moment, which depending on loading is a bending moment or torsion moment, is described as stiffness. The stiffness and thus the deformability of a structural part are dependent not only on the elastic characteristics of the material, such as the modulus of elasticity, but also significantly on the geometry of the structural part. In other words, the deformation characteristics of the deformation element 8 according to the invention are substantially dependent on the characteristics of the material used and on the construction of said deformation element.

[0087] The construction of the deformation element 8 is determined by the respective part geometry, in particular the cross-sectional shapes used, specifically the length and cross-sectional profile, and the material thicknesses.

[0088] In the example illustrated here, not the entire base support 1 is of deformable design. Instead, only a part of the base support 1, specifically the integral deformation element 8, is deformable. The deformation element 8 forms an integral storage member which is formed as a single piece with the base support 1 and which serves as an energy store.

[0089] The base support 1 has a central main body 31, which comprises inter alia the cone receptacle 2 for the chair post 20 and in which the main pivot axis 11 of the pivot mechanism 10 runs. Proceeding from this main body 31, a connecting piece 33 of the base support 1 extends forward as viewed in the seat longitudinal direction 14, and is connected to the front end of the seat support 3, with the formation of the rotary joint 23. The connecting piece 33 is in this case formed as a single piece with the main body 31. By contrast to the relatively solid, non-deformable main body 31, the connecting piece 33 is of deformable design at least in certain sections. The connecting piece 33 serves as deformation element 8 within the meaning of the invention.

[0090] The desired movement of the mechanism 10, in particular the nature of the pivoting movement, is, according to the invention, definably influenced in that the deformation behavior of the connecting piece 33 is predefined in targeted fashion. This is realized preferably by virtue of the connecting piece 33 being divided in the direction of its longitudinal extent, and thus in the seat longitudinal direction 14, into sections of different stiffness. This results in a different bending behavior (deformation behavior) of the respective sections and thus in a certain predefinable deformation behavior of the connecting piece 33. There are preferably no abrupt changes in stiffness. Instead, continuous stiffness profiles are formed.

[0091] The desired deformation behavior that differs in different sections is realized for example by means of structural measures, for example different material thicknesses, and/or through the targeted use of materials with different deformation characteristics.

[0092] In the exemplary embodiment as per FIGS. 2 to 5, the deformable section of the connecting piece 33 extends substantially over the entire length of the connecting piece 33. Here, a central section 34 has a lower stiffness than the attachment regions 35, 36 which adjoin the two ends of the central section 34 and which, with their greater stiffness, serve for the attachment of the connecting piece 33 to the main body 31 of the base support 1 and to the seat support 3.

[0093] In other words, only the two end regions 35, 36 of the connecting piece 33 are of substantially rigid form. This relates on the one hand to the rear end region 35 of the connecting piece 33, which connects the connecting piece 33 in single-piece form to the main body 31. On the other hand, this relates to the front end region 36 of the connecting piece 33, by means of which the connecting piece 33 is connected to the seat support 3, with the formation of a rotary joint 23. The connecting piece 33 is advantageously deformable throughout from directly at the front end region 36 as far as the rear end region 35, wherein the deformability decreases in the direction of the main body 31.

[0094] Owing to its deformability throughout, the deformable central section 34 of the connecting piece 33, which forms the actual deformation element 8, forms a series of virtual centers of rotation arranged in a row in the direction of the longitudinal extent of said central section. Despite the fact that there are theoretically an infinite number of virtual centers of rotation, a selection of these virtual centers of rotation 28, 29, 30 is shown in FIGS. 2 and 4.

[0095] The connecting piece 33 is preferably formed such that the stiffness of the deformable section 34 as a whole continuously changes. The changing stiffness profile arises here solely from a change in the material thickness of the deformable section 34. Proceeding from the rear end region 35, the material thickness of the central section 34 decreases continuously in the direction of the front end region 36 until the front end region 36 and thus the connecting region of base support 1 and seat support 3 is reached. The front end region 36 itself is not deformable. The deformation element 8 thus formed has, between its rigid end regions 35, 36, a soft stiffness characteristic throughout, which runs in the seat longitudinal direction 14.

[0096] In another exemplary embodiment (not shown), in which a different movement of the pivot mechanism 10 arises owing to a different deformation behavior of the connecting piece 33, the connecting piece 33 has two deformable subsections which are arranged spaced apart from one another along the direction of extent of the connecting piece 33, that is to say in the seat longitudinal direction 14. The two deformable subsections are separated from one another by a subsection which is not deformable or is considerably less deformable, and which is therefore more or less rigid. The front deformable subsection as viewed in the seat longitudinal direction 14 is connected by means of a front end region to the seat support 3, whereas the rear deformable subsection is connected by means of a rear end region to the main body 31 of the base support 1. The deformation element 8 thus formed therefore has, between its rigid end regions, a soft-rigid-soft stiffness characteristic running in the seat longitudinal direction 14.

[0097] In the exemplary embodiments described above, the deformation element 8 is designed to be deformable in the seat longitudinal direction 14 and is deformed owing to the stresses acting in this direction in the seat longitudinal direction 14. The virtual axes of rotation formed by the virtual centers of rotation 28, 29, 30 lie transversely with respect to the seat longitudinal direction 14.

[0098] The design of the connecting piece 33 is preferably selected such that the characteristics of its deformation are independent of whether increasing or decreasing loading with a force or with a moment is occurring. In other words, the deformation resistance of the connecting piece 33 and thus the pivoting resistance of the chair mechanism 10 is not dependent on whether the backrest support 4 is being pivoted rearward, and thus the connecting piece 33 as energy store is being charged, or whether the backrest support 4 is pivoting back into its initial position in a forward direction. In both situations, the deformable section 34 of the connecting piece 33 moves on the same path.

[0099] Force is introduced in two different ways into the pivot mechanism 10 in the region of the connection of seat support 3 and base support 1, in particular into the rotary joint 23. The introduction of force takes place on the one hand as a result of a movement of the seat support 3 effected by a pivoting of the backrest support 4 in the pivoting direction 7 (first load situation). The introduction of force then takes place substantially horizontally. The direction of action of the force in the first load situation is indicated in FIG. 2 by the arrow 26. The connecting point of seat support 3 and base support 1 is subjected to a rearwardly acting tensile load. On the other hand, the introduction of force takes place, as a result of a user sitting down on the chair, in particular into the front edge of the seat, resulting in loading of the front region 24 of the seat support 3 (second load situation). The introduction of force then takes place substantially vertically. The direction of action of the force in the second load situation is indicated in FIG. 2 by the arrow 27. The connecting point of seat support 3 and base support 1 is subjected to a downwardly acting compressive load.

[0100] In the simplest case, the deformation element 8 is in the form of a beam or plate. In the example shown in FIGS. 2 to 5, the deformation element 8 is designed in the manner of a leaf spring. It then has a rectangular cross-sectional profile. The deformation element 8 then behaves in the same way in both load situations.

[0101] The stiffness of the deformation element 8 is however preferably dependent on the direction of action of the force acting on the deformation element 8, in particular such that the deformation element 8 has a relatively low stiffness, that is to say deforms to a greater degree, in the first load situation than in the second load situation, in which the deformation element 8 has a relatively high stiffness, that is to say deforms to a lesser degree.

[0102] It is thereby ensured that, despite the deformability of the deformation element 8 that is required for the rearward pivoting movement, the seat front edge does not unexpectedly sink too low when a user sits down on the chair. In the ideal case, the base support 1 is completely rigid in the second load situation, whereas in the first load situation it allows the desired pivoting movement owing to its deformability. In practice, by means of the designs described here, it is achieved that no significant sinking of the front region 24 of the seat support 3 takes place, or such sinking is reduced to a minimum.

[0103] In order to achieve that the two load situations lead to different behavior of the deformation element 8, the deformation element 8 may be constructed such that, in the load situation, either only compressive loading or only tensile loading occurs.

[0104] This can be attained for example by virtue of the deformation element 8 being constructed from multiple members, for example in the form of a combination of multiple elements acting in parallel, or by virtue of a single-member connecting piece having a suitable internal construction or a suitable internal structure in order to be able to react with different deformation behavior to forces acting from different directions.

[0105] Variants of such designs of the connecting piece will be discussed in more detail below.

[0106] In one variant, as illustrated in FIG. 6, the deformable section 34 of the connecting piece 33 is formed from two members such that, between the main body 31 of the base support 1 and the front end region 36, which provides the connecting region of base support 1 and seat support 3, a division of the section 34 into an upper link member 38 and a lower link member 39 is provided. In other words, the deformable section 34 between the rear end region 35 and the front end region 36 is formed by two link members 38, 39 which run spaced apart from one another. Here, the two link members 38, 39 behave in the manner of edge axes of a beam in bending in the context of the science of strength of materials, whereas the neutral axis, which is illustrated in FIG. 6 by a dashed line 15, runs in the empty intermediate space 37 between the two link members 38, 39.

[0107] In the first load situation, the application of a horizontally rearwardly acting tensile load to the third rotary joint 23, which serves as the connecting point of seat support 3 and base support 1, leads to compressive loading of the upper link member 38 and simultaneously to tensile loading of the lower link member 39. In the second load situation, the application of a vertically downwardly acting compressive load to the rotary joint 23 leads to tensile loading of the upper link member 38 and simultaneously to compressive loading of the lower link member 39. In practice, depending on how a user moves on the chair, it is also possible in both load situations for deviations in the direction of the tensile or compressive loads to arise, instead of ideally horizontally rearwardly or vertically downwardly acting forces. Then, the horizontally rearwardly acting tensile load in the first load situation or the vertically downwardly acting compressive load in the second load situation are supplemented by further load components, which are however of considerably smaller magnitude than the forces acting in the main load directions, such that the fundamental functional principle described here does not change.

[0108] By means of a different construction of the two link members 38, 39, it is advantageously achieved that the behaviors of the link members 38, 39 differ from one another.

[0109] In one embodiment, it is the intention that the deformation behavior of the upper link member 38 under tensile load differs from the deformation behavior under compressive load such that the elongation under compression is greater than the elongation under tension. In other words, it is the intention that the upper link member 38 be rigid under tension and at the same time soft under compression. At the same time, it is the intention that the deformation behavior of the lower link member 39 under tensile loading does not differ from the deformation behavior under compressive loading. The lower link member 39 is therefore again provided with a rectangular cross-sectional profile, and is in particular formed as a solid plate.

[0110] The fact that the upper link member 38 reacts differently under compression and under tension, and does so in the desired manner, specifically such that excessive elongation under tension is prevented, is achieved in the illustrated example by means of a special construction of the upper link member 38, which allows a limitation of the elongation by means of stops in the case of tensile loading, whereas stops are not provided for such a limitation in the case of compressive loading. For this purpose, it is provided that the upper link member 38, the basic form of which is likewise a plate, is constructed from hollow cells, such that a high mechanical stiffness is generated despite the relatively low weight of the hollow body structure that is formed. The construction is honeycomb-shaped, that is to say the cells 40 from which the upper link member 38 is constructed directly adjoin one another. Here, the cavities 42 of the cells 40 have a square shape in cross section and are oriented obliquely with respect to the seat longitudinal direction 14, resulting in the form of rhombuses. In this way, relatively large, in this case compression-induced deformations can be realized without this leading to high stresses in the material. The cell walls 43 run in this case such that they can deform during the movement sequence, in this case advantageously transversely with respect to the seat longitudinal direction 14.

[0111] The rod-shaped stop elements 41 are arranged in each case pairwise in the cavities 42 of the cells 40, specifically such that mutually associated stop elements 41 butt with their head ends against one another under tensile loading of the upper link member 38 and thus prevent further elongation of the upper link member 38. At the same time, the compressive loading of the lower link member 39 occurs.

[0112] In this way, an undesired deformation of the connecting piece 33, and thus sinking of the front region 24 of the seat support 3 in the second load situation are reduced, whereas the desired pivoting movement in the first load situation is both allowed and also not impeded. Alternative constructions of the upper link member 38 are likewise possible.

[0113] The resulting deformation behavior of the connecting piece 33 influences the movement or the movement path of the connecting point of seat support 3 and base support 1, which is formed by the rotary joint 23. On the other hand, the magnitude of the opposing force, and thus the pivoting resistance of the chair mechanism 10 during a pivoting of the backrest support 4 rearward, are thus also defined.

[0114] In an alternative variant as illustrated in FIGS. 7 and 8, the connecting piece 33 is again of single-member form. The deformable section 34 is however constructed from planes 48, 49 lying one above the other which differ from one another in terms of construction and which, for this reason, likewise have different deformation behavior. The planes 48, 49 run, like the link members 38, 39 previously, correspondingly to the longitudinal extent of the connecting piece 33 in the seat longitudinal direction 14.

[0115] There is at least one upper plane 48, which is preferably the uppermost plane of the deformable section 34, and at least one lower plane 49, which is preferably the lowermost plane of the deformable section 34, which planes both behave in the manner of edge axes of a beam in bending in the context of the science of strength of materials, whereas the neutral axis 15 runs in an intermediate plane 47 between said two planes 48, 49.

[0116] The entire plate-like connecting piece 33 is constructed as a hollow chamber structure. The upper plane 48 corresponds in terms of its construction to the upper link member 38 of the variant described above. The intermediate plane 47 and the lower plane 49 are likewise of honeycomb construction with cells which directly adjoin one another. As in the variant described above, the thickness of the cell walls is relatively small in relation to the dimensions of the cavities, such that the desired deformability is made possible.

[0117] In the first load situation, the application of a horizontally rearwardly acting tensile load to the connecting point of seat support 3 and base support 1, formed by the rotary joint 23, leads to compressive loading of the upper plane 48 and simultaneously to tensile loading of the lower plane 49. In the second load situation, the application of a vertically downwardly acting compressive load to the rotary joint 23 leads to tensile loading of the upper plane 48 and at the same time to compressive loading of the lower plane 49.

[0118] Again, in the case of tensile loading, the elongation of the upper plane 48 is limited by stops, whereas no corresponding limitation is provided for a deformation caused by compressive loading. The stops provided in the upper plane 48 are formed in the same way as in the variant illustrated in FIG. 6, that is to say by means of stop elements 41, 42 which, under tensile loading of the upper plane 48 in the second load situation, butt against one another and thus prevent excessive elongation of the upper plane 48.

[0119] The deformation behavior of the upper plane 48 under tensile load differs from the deformation behavior under compressive load such that the elongation under compression is greater than the elongation under tension. In other words, the upper plane 48 is rigid under tension and soft under compression.

[0120] In FIGS. 6 and 7, the neutral axes 15 are shown symbolically centrally between the two link members 38, 39 or planes 48, 49; in fact, the neutral axis 15 runs very much closer to the lower link member 39 or the lower plane 49.

[0121] The principal of using structurally and/or functionally separate link members or planes in the construction of the connecting piece 33 can also be transferred to other embodiments of the invention. It can advantageously thus be achieved that the connecting piece 33 has deformation behavior with which it deforms more intensely in the first load situation than in the second load situation. The deformable section 34 of the connecting piece 33 is softer during pivoting of the backrest support 4 rearward than in the event of loading of the front region 24 of the seat support 3 owing to the seat front edge being sat on. Ideally, the deformable section 34 of the connecting piece 33 is rigid or substantially rigid in the event of loading of the front region 24 of the seat support 3, whereas said deformable section allows a desired deformation during a pivoting of the backrest support 4 rearward.

[0122] In a further variant as illustrated in FIGS. 9 and 10, the deformable section 34 of the connecting piece 33 does not extend all the way to the third rotary joint 23. The front end region 36, specifically the rigid region of the connecting piece 33 which provides the space for the rotary joint 23, thus extends in the direction of the main body 31 to such an extent that the deformable section 34 of the connecting piece 33, which is again of two-member form with an upper link member 38 and a lower link member 39, connects to the front end region 36 such that the two link members 38, 39 meet, forming a virtual center of rotation 51, at a point which is spaced apart from the position of the transverse axis 13 assigned to the rotary joint 23. The rotary joint 23, more specifically the transverse axis 13, is in this case arranged exactly perpendicularly across the virtual center of rotation 51. The spacing 52 between the virtual center of rotation 51 and the transverse axis 13 determines a lever of defined length. If the two link members 38, 39 meet the front end region 36 with a spacing to one another, this gives rise to a resulting virtual center of rotation which is arranged exactly vertically below the transverse axis 13.

[0123] In the first load situation, the force acting on the rotary joint 23 generates, owing to this lever, a torque which acts both on the upper link member 38 and on the lower link member 39 and which subjects both link members 38, 39 to bending load, see FIG. 10. In other words, the two link members 38, 39 are bent. The connecting piece 33 allows such a deformation.

[0124] In the second load situation, the load direction, that is to say the line of action 27 of the force acting on the rotary joint 23, runs through the virtual center of rotation 51, see FIG. 9. Since the lever is therefore not effective, the torque acting on the connecting piece 33 is equal to zero. The lower link member 39 is then subjected exclusively to compressive loading, whereas the upper link member 38 is subjected exclusively to tensile loading. Therefore, in this load situation, virtually no forces arise that would cause bending of the link members 38, 39. Therefore, no significant deformation of the connecting piece 33 occurs.

[0125] The link members 38, 39 are for example in the form of rods. Alternative embodiments, in which the link members 38, 39 are in the form of beams, plates etc., are likewise possible.

[0126] Aside from the shapes and the profiles of the cross sections of the link members 38, 39, the selected lengths of the link members 38, 39, and the positions of the attachment of the link members 38, 39 to the main body 31 of the base support 1, and the selection of the angles that the link members 38, 39 assume relative to the horizontal, play a role in the provision of the desired link member functionality. In particular, the form of the movement of the seat support 3 and the magnitude of the resetting forces can thus be set in targeted fashion.

[0127] A divergence of the position of a real rotary joint 23 and the position of a virtual center of rotation 51 that arises owing to the use of a deformation element 8 according to the invention, for the purposes of generating movement differences that are dependent on the load situation, can also be transferred to other embodiments of the invention.

[0128] Before a description is given of a second and a third pivot mechanism and other exemplary embodiments, further characteristics of the deformation element 8 will be discussed below, which may be relevant both in conjunction with the first pivot mechanism and in conjunction with said other exemplary embodiments and in conjunction with other exemplary embodiments of the invention that are not described here.

[0129] The pivot mechanism 10 that is to be provided is subject to cycling loading and, for this reason, must withstand up to several hundred thousand load cycles. In order that the fatigue strength is ensured, the force loss (relaxation) that occurs under deformation must be limited. This is preferably achieved in that the pivot mechanism 10 is not subjected to any permanent and high prestress.

[0130] A certain low prestress is duly already present in the system owing to the tolerances in the dimensional accuracy of the structural parts. A low prestress may also be desired and necessary in order that the backrest stands upright in the first place. In a preferred embodiment, a pivot mechanism 10 which has a deformation element 8 according to the invention is however constructed such that no significant prestress of the deformation element 8 is required. The prestress of the deformation element 8 is at any rate so low, in all variants according to the invention, that no functionality-impairing relaxation of the deformation element 8 occurs.

[0131] This freedom from prestress is preferably realized by virtue of the fact that the chair mechanism is constructed as a so-called “self-setting” mechanism, as discussed below.

[0132] The invention can be used in chair mechanisms 10 with different numbers n of real centers of rotation (n=0, 1, 2, 3, . . . ).

[0133] The nature of the pivoting movement, in particular the relative movement of seat support 3 and backrest support 4 with respect to one another, is significantly determined by the position of the centers of rotation with respect to one another.

[0134] It has proven particularly advantageous for the invention to be used in chair mechanisms 10, in particular synchronous mechanisms, which are designed as “self-setting” mechanisms. These are distinguished by the fact that the weight of the user sitting on the chair counteracts the pivoting movement. In other words, the user of the chair raises themself upward by means of a load on the backrest, in that, in actuating the chair mechanism 10 by pushing the backrest backward, said user acts counter to their own weight resting on the seat. The desired pivoting resistance is thus, as it were, set automatically owing to the weight of the user.

[0135] Owing to the principle of “self-setting”, the weight of the user generates an adequately high torque on the backrest support 4. Said torque can be accommodated entirely or partially by the deformation element 8 that acts as an energy store member. Therefore, no high prestresses are required.

[0136] Preferably, by means of the selected position of the centers of rotation or pivot axes 11, 12, 13, a lever geometry required for a self-setting mechanism 10 is provided, in the case of which, both in the non-pivoted basic position and preferably also in the position pivoted rearwardly to a maximum extent, the main pivot axis 11, which is arranged transversely with respect to the seat longitudinal direction 14, of the connection of the backrest support 4 to the base support 1 is, as viewed in the seat longitudinal direction 14, arranged behind the articulation point 22 of the backrest support 4 to the seat support 3, that is to say behind the pivot axis 12 that defines the location of the introduction of force into the seat support 3.

[0137] A pivoting of the backrest support 4 rearward then causes a raising of the seat support 3 correspondingly to the movement curve defined by the interaction of backrest support 4, base support 1 and seat support 3. In particular, a pivoting of the backrest support 3 rearward in the pivoting direction 7 causes a direct raising movement of the rear region 25 of the seat support 3 and simultaneously a direct raising movement of the front region 24 of the seat support 3. By virtue of the fact that the seat support 3 is not only raised in its rear region 25 but a raising of the front region 24 of the seat support 3 also occurs simultaneously, the seat support 3 is synchronously driven along rearwardly and upwardly in a defined relationship with respect to the backrest support 4. Since, during a pivoting of the backrest into a rear position, the user sitting on the seat surface performs a movement that tracks the movement of the backrest, the so-called “shirt riding-up effect” is prevented in a particularly effective manner.

[0138] The deformation element 8 according to the invention can also be used in chair mechanisms that are not designed as “self-setting” mechanisms, in particular in mechanisms in which the presence of a non-negligible prestress is required for correct functioning. These may in particular be “hybrid” chair mechanisms which, aside from the deformation element 8 according to the invention, use separate energy store elements such as steel springs.

[0139] In the case of the use according to the invention of a deformation element 8 as part of a component or assembly of a chair mechanism 10, it is preferable for stops to be provided which, as force-accommodating elements, prevent overloading of the deformation element 8 both during a pivoting movement of the backrest support 4 or of the seat support 3 into the front and rear end positions and in the case of an exertion of load on the seat support 3 by a user, which leads to a sinking movement of the seat support 3. In other words, stops for absorbing seat loads, that is to say for absorbing movements of mechanism components downward, and stops for limiting the movement of mechanism components forward and rearward, are preferably provided. The movement of the chair mechanism as a whole downward is typically limited by a gas spring which is installed in the chair post 20 and which provides a suitable stop.

[0140] Preferably, stops are provided which limit a movement of the pivot mechanism 10 forward and rearward such that the loads caused by the pivoting movement of the mechanism are not transmitted via the deformation element 8. Suitable stop surfaces are typically formed on the base support 1.

[0141] A second pivot mechanism 10 will be described below. This substantially corresponds in terms of its basic construction to the first pivot mechanism as shown in FIGS. 2 to 5, but differs in the embodiment of the connecting piece 33, which is designated below as fifth embodiment.

[0142] In the embodiment shown in FIGS. 11 and 12, as in the case of the variant illustrated in FIGS. 7 and 8, the deformable section 34 of the connecting piece 33 is constructed from planes 48, 49 lying one above the other, which planes differ from one another in terms of construction and, for this reason, exhibit different deformation behavior.

[0143] The construction of the connecting piece 33 substantially corresponds to the construction of the connecting piece 33 illustrated in FIG. 7. The upper plane 48 however, by contrast thereto, has no stop element.

[0144] Whereas the upper plane 48 is formed with a closed top side, it is a special feature of the fifth embodiment of the connecting piece 33 that the lower plane 49 is designed such that, in the plane structure, there are provided a multiplicity of slots 64 which are spaced apart from one another in the seat longitudinal direction 14 and which run in the transverse direction and the slot openings of which point downward. The slots 64 are, in other words, formed in the bottom side 65 of the lower plane 49.

[0145] In the unloaded basic position of the chair mechanism 10, in which neither the backrest support 4 is pivoted rearward nor the seat support 3 is subjected to load by a user, the slots 64 are in their normal state, in which they are open to a minimal extent. The walls, which define the slots 64, of the lower plane are in other words spaced apart from one another by a thin air gap in the region of the slots 64.

[0146] In the first load situation, which causes a tensile loading of the lower plane 49, the slots 64 open. The connecting piece 33 is softer, that is to say has a lower stiffness, than in the second load situation.

[0147] In the second load situation, which causes a compressive loading of the lower plane 49, the slots 64 close. The walls, which define the slots 64, of the lower plane 49 make contact with one another. The opposing force that counteracts the compressive load that acts in the event of load being exerted vertically downward on the front region 24 of the seat support 3 increases. The connecting piece 33 becomes harder, that is to say has a higher resistance to deformation, than in the first load situation.

[0148] As a result of the opening and closing of the slots 64 in the lower plane 49, in the context of the science of strength of materials, the position of the neutral axis 15 within the deformable section 34 is shifted, and thus the spacing of the neutral axis 15 to the upper edge axis (not illustrated), which runs close to the top side 66 of the upper plane 48, is varied. In this way, the flexural stiffness of the connecting piece 33 is directly influenced. By means of the number, arrangement and design of the slots 64, in particular the depth thereof, the deformability of the connecting piece 33 can be predefined.

[0149] As a result, the deformable section 34 of the connecting piece 33 is rigid in the event of loading of the seat front edge, that is to say loading of the front region 24 of the seat support 3, whereas said deformable section allows a deformation during a pivoting of the backrest support 4 rearward.

[0150] As in all of the other embodiments of the invention described here, the connecting piece 33 is designed such that the required stiffness is present in order to achieve the desired pivoting resistance with respect to the pivot mechanism 10 during a pivoting of the backrest support 4. The stiffness of the deformation element 8 corresponds figuratively to a hardness, attainable by means of a certain spring rate, of a separate spring element such as is used in conventional pivot mechanisms instead of the integral deformation element 8 according to the invention.

[0151] As is also the case in the above-described mechanism variants, it is advantageously the case that a stop (not shown) is provided between base support 1 and backrest support 4, which stop, when the chair is sat on, prevents an excessive forward movement of the backrest support 4 counter to the pivoting direction 7.

[0152] The principal of a movement limitation achievable by means of slots 64 or other suitable openings is also transferable, if required, to the upper link member or the upper plane. Likewise, this principle is combinable with further variants, or can be transferred to other embodiments of the invention. Accordingly, the connecting piece 33 may advantageously be equipped with an upper link member or an upper plane with stop elements 41, 42 and simultaneously with a lower link member or a lower plane with slots 64.

[0153] A third pivot mechanism 70 will be described below. The pivot mechanisms 10 described above have three real centers of rotation that have been defined by rotary joints 21, 22, 23 with transverse axes 11, 12, 13. The invention is however also applicable to pivot mechanisms with a different number of real centers of rotation. By way of example, below, the use of a deformation element 8 within the meaning of the present invention will be described in the case of a pivot mechanism 70 with only one real rotary joint. In other words, the three rotary joints 143, 144, 145 shown in FIG. 1 are replaced by virtual centers of rotation.

[0154] It is again the case here that a synchronous mechanism 70 is involved, the basic position of which, in which the seat support 3 assumes a substantially horizontal position, is shown in FIG. 14.

[0155] The backrest support 4 which is pivotable in the pivoting direction 7 is, by way of its web 5 which extends in the direction of the front region 17 of the mechanism 70, directly articulatedly connected by way of the single rotary joint 72 to the base support 1, with the formation of the single pivot axis 71 of the mechanism 70. To produce this connection, use is made, in simple cases, of either a plug-in axle or of two collar screws. During the assembly process, the base support 1 is mounted, with the application of a low prestress, onto the backrest support 4. The resulting pivot axis 71 again lies, as viewed in the seat longitudinal direction 14, behind the cone receptacle 2.

[0156] As before, the base support 1 is formed by a main body 31 and a connecting piece 33 which is formed in single-piece fashion with the main body 31. In the front region 17 of the mechanism 70, the front region of the base support 1, specifically the front end 73 of the connecting piece 33, is connected in single-piece fashion to the front region 24 of the seat support 3. Here, the front region 24 of the seat support 3 is of rigid form, whereas the front end 73 of the connecting piece 33, as part of the deformable section 34 of the connecting piece 33, forms a virtual center of rotation 74 at the location of the transition to the seat support 3, which virtual center of rotation performs the function of the rotary joint 23 of the pivot mechanism 10 illustrated in FIGS. 2 to 5.

[0157] Again, it is the deformability of a mechanism component or of a part of a mechanism component, in this case the deformability of the deformable section 34 of the connecting piece 33 of the base support 1, that allows the pivoting functionality of the chair mechanism 70 in the first place.

[0158] The following movement of the seat support 3 during a pivoting of the backrest support 4 into the rearwardly pivoted position is, in this exemplary embodiment, furthermore made possible by virtue of the fact that, instead of a rotational articulated connection, defined by a transverse axis, of the backrest support 4 to the seat support 3, a film joint 75, 175 is used which connects the backrest support 4 and the seat support 3 to one another in single-piece form.

[0159] In the rear region 16 of the mechanism 70 as viewed in the seat longitudinal direction 14, it is the case, for this purpose, that the backrest support 4 is equipped with an initially upwardly extending driver 76 of the web 5, which is subsequently caused to project such that its connecting end 77 extends forward in the seat longitudinal direction 14. The projecting part of the driver 76 in this case runs parallel to the seat support 3. The seat is however connected only to the seat support 3, not to the backrest support 4. The connecting end 77 projects forward to such an extent that, as viewed in the seat longitudinal direction 14, the pivot axis 71 is again arranged behind the pivot axis formed by the film joint 75, 175.

[0160] The variant of the mechanism 70 that uses the film joint 75 will be described in conjunction with FIGS. 13 to 15. The connecting end 77 of the driver 76 in this case interacts with the rear end 78 of the seat support 3, with the formation of a butt-jointed connection. This connecting arrangement comprises on the one hand the film strip, formed in single-piece fashion on the bottom sides of driver 76 and seat support 3, of the film joint 75, with a thin-walled joint groove 79, which runs in the transverse direction. On the other hand, the connecting arrangement comprises vertically lying end-side abutting surfaces 81, 82, running in the transverse direction, of driver 76 and seat support 3, which abutting surfaces lie fully areally against one another in the non-pivoted basic position, see FIG. 14.

[0161] A pivoting of the backrest support 4 out of the basic position into a rearwardly pivoted position is associated with a raising movement of the driver 76. As a result, the abutting surfaces 81, 82 of driver 76 and seat support 3 move away from one another. At the same time, backrest support 4 and seat support 3 remain connected to one another via the film joint 75, see FIG. 15. The seat support 3 follows the pivoting movement of the backrest support 4 rearward.

[0162] In order to keep the mechanical loading on the film joint 75 as low as possible, the position of the film joint 75 is advantageously selected such that the joint is subjected only to tensile loading, whereas bending and shear are minimized. To satisfy this condition, in the first load situation, the film joint 75 would have to be in a very steep, ideally vertical, situation, whereas, in the second load situation, it would ideally have to lie horizontally. In the position of the virtual and real centers of rotation of the pivot mechanism 70 illustrated in FIG. 14, in particular when the pivot axis 71 lies, in the seat longitudinal direction 14, behind the pivot axis 83 which connects the backrest support 4 and the seat support 3 to one another and which is defined by the profile of the joint groove 79 of the film hinge 75, the illustrated position of the joint 75, in which the joint lies in the direction of the force resulting from seat weight and leaning-back movement, has proven to be particularly advantageous for a lowest possible mechanical loading.

[0163] Since all of the components of the pivot mechanism 70 are connected in single-piece form to one another, manufacturing “in one shot” is possible. In other words, a single-piece assembly composed of the backrest support 4, the seat support 3 attached to the backrest support 4 by means of the film joint 75 and the base support 1 attached to the seat support 3 by means of the connecting piece 33, can be produced with a single filling of a single injection molding tool.

[0164] The variant of the mechanism 70 which, with the film joint 175, uses a different film joint design, will be described in conjunction with FIGS. 16 and 17. As above, during the assembly process, the base support 1 is mounted, with the imparting of a low pre-stress, onto the backrest support 4. This variant of the mechanism 70 is also producible “in one shot”. In the case of the film joint 175, however, it is not sought to position the joint in the direction of the force resulting from seat weight and leaning-back movement. Instead, multiple different bending regions are provided which are each optimized for a particular loading direction. In this way, the mechanical loading of the mechanism 70 can be further reduced. A pivoting of the backrest support 4 out of the basic position into a rearwardly pivoted position is, as already discussed in conjunction with FIGS. 13 to 15, associated with a raising movement of the driver 76. Here, backrest support 4 and seat support 3 remain connected to one another by means of the film joint 175. The seat support 3 follows the pivoting movement of the backrest support 4 rearward.

[0165] The connecting arrangement provided for this purpose comprises a film joint 175 with two different types of hinge strips. A single, centrally arranged first hinge strip 88 is formed in single-piece fashion on the bottom sides of driver 76 and seat support 3. Said first hinge strip 88 is designed for transmitting a tensile load when, with a leaning-back movement, the seat support 3 pulls the backrest support 4 forward. To minimize the mechanical loading of the film joint 175, the first hinge strip 88 is arranged substantially horizontally in the non-pivoted state of the backrest support 4.

[0166] Second hinge strips 89 are arranged to both sides of the first hinge strip 88. Said two second hinge strips 89 are formed in single-piece fashion with the top side of the driver 76 and the bottom side of the seat support 3 and therefore, in the non-pivoted state of the backrest support 4, run at a steep angle of preferably at least 60° with respect to the horizontal. They are designed for transmitting vertically acting forces such as arise as a result of a loading of the seat support 3 by the sitting weight of a user. In other words, the two hinge strips 88, 89 have mutually different spatial positions.

[0167] All hinge strips 88, 89 of the film joint 175 have thin-walled joint grooves 79 running in the transverse direction. Despite the fact that the two hinge strips 88, 89 which serve as film joint elements have mutually different positions in space, the joint grooves 79 of the hinge strips 88, 89 lie relative to one another so as to result in a common pivot axis 83, defined by the profile of the joint grooves 79, for the articulated connection of the backrest support 4 to the seat support 3, as shown in FIG. 17.

[0168] The immediately above-described variant of the mechanism 70 is applicable in particular if the connecting arrangement no longer has abutting surfaces, because the backrest support 4 and the base support 1 themselves provide stops (not illustrated) which serve for limiting the movement of said mechanism components with respect to one another and ensure reliable use of the mechanism 70.

[0169] Instead of the film joint 75, use may also be made of a further deformation element 8 for articulatedly connecting the seat support 3 to the backrest support 4. Said further deformation element may be designed as a hollow chamber component, similarly to the connecting part 33, as shown in FIGS. 7 and 11. The mechanism 70 would then have two deformation elements 8 according to the invention.

[0170] The concept of using a suitably designed component, that is to say a component which is distinguished by suitable material selection and suitable parts geometry, in order to be able to omit a separate spring arrangement, a number of spring elements or some other energy store for the provision of a pivoting movement or the realization of a movement of a component of an item of seating furniture, in particular the resetting of a backrest support in the case of an office chair, can be used not only in pivot mechanisms 10, 70, for example as specified further above. A structural-part-integrated deformation element 8, which in particular serves as energy store, may also be used in some other way in a chair mechanism. For example, a backrest rod may be used as such a deformation element which is integrated into a component.

[0171] Here, all statements with regard to the characteristics of the material to be used and the material selection, and with regard to the geometrical design, that have been made above in conjunction with a deformation element 8 described there and serving as a component of a pivot mechanism are also transferable to deformation elements 8 whose deformability is not imperatively related to the practicability of the pivoting movement of a chair mechanism but which serve merely as components or component parts which provide a certain mobility of a mechanism or of a mechanism assembly. In other words, the deformation element 8 may also be used in such a way that it is not imperatively required for an implementation of a movement of the chair mechanism as a whole, but merely allows a movement of a single part, of a component or of an assembly of a chair mechanism or of some other part of a chair or of some other item of seating furniture.

[0172] The invention is applicable not only to chair mechanisms and the components or assemblies thereof. The integrated deformation element 8 according to the invention that has been described above by way of example in the form of a connecting piece 33 or of a deformable section 34 may also be used in other parts of a seat assembly, in the backrest, in the armrests, in the seat, in further attachment parts of the chair or in a subframe, such as a cruciform base, in order to serve as an energy store.

[0173] The deformation element 8 is preferably the only energy-storing component of the device 1, 10 according to the invention. The deformation element 8 may however also be combined with other energy-storing structural parts, whilst achieving additional advantages.

[0174] The positions of the rotary points relative to one another and relative to other structural elements of the mechanism, as mentioned in conjunction with the above-described exemplary embodiments of individual pivot mechanisms, are to be understood merely as examples for specific advantageous variants of the invention. The invention is also applicable to pivot mechanisms which have some other arrangement of the rotary points.

[0175] The invention has been described above primarily in conjunction with bending deformations of the deformation element, which serve for realizing a pivoting movement. It is however also possible for deformation elements to be provided which are based on a bending deformation for realizing a tilting movement or some other movement. Also, other deformations of deformation elements, such as for example torsional deformations, are possible for the purposes of realizing the same or other movements. Likewise possible are intentionally effected combinations of deformation types, for example simultaneous bending and torsional deformations, in particular for the purposes of realizing superposed movements, in more than one spatial direction, of the devices which have the deformation elements.

[0176] All of the structural and functional features, characteristics and advantages discussed in conjunction with the deformation element with regard to one exemplary embodiment of the invention are also transferable to the other exemplary embodiments.

[0177] All of the features presented in the description, in the following claims and in the drawing may be essential to the invention both individually and in any desired combination with one another.

LIST OF REFERENCE DESIGNATIONS

[0178] 1 Base support [0179] 2 Cone receptacle [0180] 3 Seat support [0181] 4 Backrest support [0182] 5 Web [0183] 6 Driver [0184] 7 Pivoting direction [0185] 8 Deformation element, storage member [0186] 9 Pivot angle [0187] 10 Synchronous mechanism [0188] 11 First transverse axis, main pivot axis [0189] 12 Second transverse axis [0190] 13 Third transverse axis [0191] 14 Seat longitudinal direction [0192] 15 Neutral axis [0193] 16 Rear region of the mechanism [0194] 17 Front region of the mechanism [0195] 18 Front region of the base support [0196] 19 Transverse direction [0197] 20 Chair post [0198] 21 First rotary joint [0199] 22 Second rotary joint [0200] 23 Third rotary joint [0201] 24 Front region of the seat support [0202] 25 Rear region of the seat support [0203] 26 Force direction in the first load situation [0204] 27 Force direction in the second load situation [0205] 28 Virtual center of rotation [0206] 29 Virtual center of rotation [0207] 30 Virtual center of rotation [0208] 31 Main body of the base support [0209] 33 Connecting piece [0210] 34 Central section [0211] 35 Rear end region, attachment region [0212] 36 Front end region, attachment region [0213] 37 Intermediate space [0214] 38 Upper link member [0215] 39 Lower link member [0216] 40 Cell [0217] 41 Stop element [0218] 42 Cavity [0219] 43 Cell wall [0220] 47 Intermediate plane [0221] 48 Upper plane [0222] 49 Lower plane [0223] 51 Virtual center of rotation [0224] 52 Spacing, lever length [0225] 53 Receptacle [0226] 54 Longitudinal edge [0227] 55 Limb [0228] 56 Opening [0229] 57 Tip [0230] 58 Upper member [0231] 59 Lower member [0232] 60 Partial sub-member [0233] 61 Side wall [0234] 64 Slot [0235] 65 Bottom side [0236] 66 Top side [0237] 70 Pivot mechanism [0238] 71 Pivot axis [0239] 72 Rotary joint [0240] 73 Front end [0241] 74 Virtual center of rotation [0242] 75 Film joint [0243] 76 Driver [0244] 77 Connecting end [0245] 78 Rear end [0246] 79 Joint groove [0247] 81 Abutting surface [0248] 82 Abutting surface [0249] 83 Pivot axis [0250] 86 Seat [0251] 87 Backrest [0252] 88 First hinge strip [0253] 89 Second hinge strip