Seating furniture with seat, backrest and pivoting device

Abstract

The invention relates to a seating furniture (1) with a base (2) and a seat (4) which can be pivoted about a horizontal transverse axis (26) located above the seat (4) by means of a pivoting device relative to the base (2) between an upright sitting position and a reclined resting position, and with a backrest (5), in particular an office chair. In order to improve the seating comfort and reduce the indentation of the undersides of the user's thighs when reclining, it is provided that at least one spring element (15, 24, 27) is provided which, when the seat (4) is pivoted towards the resting position, generates a restoring moment on the seat (4) in the direction of the upright sitting position.

Description

[0001] The invention relates to a piece of seating furniture with a seat surface which is pivotable about a horizontal transverse axis which lies above the seat surface by means of a pivoting device relative to a base and which has a backrest, in particular an office chair, according to EP 3 193 670 (WO 2016 / 042127 A1) or DE 10 2018 114 207 B3, and the preamble of claim 1.

[0002] Prior art includes furniture with a swivel mechanism, such as that known from EP 3 193 670, and specifically seating furniture, such as that known from EP 4 294 237 (WO 2022 / 174945 A1) and DE 10 2018 114 207 B3 (all three originating from the applicant). All these applications describe, among other things, a design for the swivel mechanism in which the seat is supported by a three-axis kinematic system with a central point, allowing spherical movement around the central point. The seat is also guided during its rotation around a (virtual) transverse axis passing through the center of the spherical movement.

[0003] Naturally, all kinematic mechanisms capable of pivoting the seat about a horizontal transverse axis located above the seat can be used. These include: EP 1 090 568 B1, EP 2 381 816 B1, WO 2012 / 123102 A1 of the applicant, WO 2016 / 042127 A1 of the applicant, in particular Fig. 9 and the associated description, explained in more detail in WO 2013 / 029069 A1 of the applicant. However, completely different kinematic systems can also be combined with the invention, such as those of DE 199 15 003 A1, or those of EP 3 476 254 A1 of the applicant.

[0004] A key aspect is that the vertical position of the swivel axis is placed in the roughly estimated lower region of the user's thoracic spine. This is because, especially when a swivel movement around a longitudinal axis lying in the plane of symmetry of the furniture is also possible—which is often desirable for health and training reasons—it promotes a comfortable movement of the pelvis and the subsequent part of the spine, similar to the movement during walking. The user's center of gravity then lies above the swivel axis, possibly even above the central point. Some terms:

[0005] Seat surface:This seat is movable relative to its base, pivotable at least about a (horizontal) transverse axis. Further pivoting about other axes, up to and including spherical mobility, may be provided. The seat surface can be divided along a horizontal axis into a front part and a rear part, which is then rigidly connected to the backrest, as known from the standard design. In this case, the distance between the backrest and the front end of the (rear) seat surface part rigidly connected to the backrest, in the area of ​​the possible articulated or flexible leg rest, is 50 mm to 300 mm. The seat surface can be upholstered; this does not change the invention.

[0006] Backrest; As stated in the application, it can be rigidly, albeit resiliently, connected to the seat surface or its rear part. It can also be rigidly, resiliently, or pivotally connected to the base around a horizontal transverse axis, as is known from the standard design.

[0007] Plane of symmetry: The furniture is divided into two parts along a vertical plane, whereby at least the seat and backrest are indeed divided into two equal parts that are symmetrical to each other; the remaining components and also the fastening elements on the seat and backrest can easily deviate from this symmetry. Regarding the term "plane of symmetry," it should be noted that this only applies with some caveats, because the individual components and handles of seating furniture, for example, office chairs, are indeed unilateral. Nevertheless, a plane of symmetry exists for the seat and, if present, the backrest and armrests, which runs vertically when the seating furniture is at rest and pivots with the seat. It is this plane that will be considered the plane of symmetry in the following discussion.

[0008] Virtual axis(s):Since the pivot axis(es) of the seat surface are located above it, they do not consist of bearings, sleeves, or similar components, but are formed by various kinematic mechanisms known from standard technical drawings, such as the aforementioned three-axis kinematic mechanism with a central point. It should be noted here that the version with a central area instead of a central point, also known from standard technical drawings, can also be used in the present invention.

[0009] As explained in detail below, the problem is that, after some time, using the aforementioned seating furniture causes the user discomfort when leaning back. Another problem, equally significant in practice, is that when leaning back around the transverse axis, the front edge of the seat is lifted and constricts the user's thighs from below. The main objective of the invention is to provide a solution for at least one of these structurally related problems, preferably both.

[0010] Since the state of the art will be explained in more detail below using the drawing, the corresponding figures are already listed here. They show, or show, the Figures 1 to 3 a conventional office chair in three views, which Figures 4 to 6 a variant with a so-called tractor seat surface and the Figs. 7 and 8 the situation when sitting upright and when sitting reclined.

[0011] Models were created according to the Figures 1 to 3 , Built and tested according to the state of the art for experimental purposes. The seating furniture, an office chair or armchair, which Figures 1 to 3 The base 6 has a frame with rollers that run on the surface 7, and a gas spring with a base 2 mounted at its upper end. This base 2 is rotatable about the vertical axis 8 of the gas spring and supports the swivel mechanism, a three-axis kinematic 3. This three-axis kinematic 3, in turn, supports the seat 4 and forms a central point 9 ( Fig. 5) around which the seat 4 and all parts connected to it are spherically movable. It should be noted that the central point 9 does not have to lie on the vertical axis 8, and usually does not, but is offset from it, usually to the rear. This spherical pivoting capability always also allows for pivoting around a horizontal normal axis onto a furniture symmetry plane. This symmetry plane 10 falls within the Figs. 2 , 5 , 6 , 7 and 8 together with the drawing plane. Of course, it is not a plane of symmetry in the mathematical sense, because the operating mechanisms and also the arrangement of the three-axis kinematics are quite asymmetrical; nevertheless, it is a common term, and for the seat and (if present) for the backrest and armrests, it is indeed a plane of symmetry that runs vertically to the base of the furniture in the resting position.

[0012] The aforementioned normal axis, the transverse axis 26 ( Fig. 6 ), is to remove the seat surface 4 and everything connected to it, specifically the backrest, from the upright sitting position of the Fig. 5 It can be swivelled backwards to a resting or even lying position. Fig. 6 This shows such a backward-tilting position, which, however, does not necessarily represent the final position. The methods for limiting this pivoting movement are well-known from the prior art and require no further explanation here.

[0013] In three-axis kinematics, movement around other axes passing through the central point 9 is always possible (but can be limited or prevented if desired); this is also known from the prior art, is not causally related to the invention, and therefore does not need to be explained here.

[0014] In this conventional chair 1, which is equipped, for example, with a continuous seat surface 4, the front edge 11 of the seat surface 4 inevitably lifts up when leaning back, as a comparison of the Figures 2 and 3 This is clearly evident. This is not only perceived as unpleasant, but also leads to medical disadvantages, as a closed seat shell (or generally a fixed position between seat and backrest) restricts the movement of the hip joint. Of course, this problem also occurs when using kinematics other than the three-axis kinematics shown.

[0015] To solve this problem, a so-called saddle seat was tested, as used in the Figures 4 to 6The figure shows a three-axis kinematic swivel mechanism with a central point 9 and a transverse axis 26 (indicated by the circle around the central point). The saddle seat with a saddle seat surface 14, sometimes also called a tractor seat, which has been used in various configurations recently, can be applied in different versions. A largely flat version was deliberately chosen, as it most closely resembles a conventional seat surface. The seat is designed to offer a recessed thigh support, like a saddle, while the central section has approximately the dimensions of a standard seat surface. This central section is necessary to ensure that a person attempting to sit on the front edge of the seat does not slip off.

[0016] As especially from Fig. 4As can be seen, a padded cushion with a saddle shape lies on the actual seat surface, which also allows for support when leaning back, as in the Fig. 6 It shows that by significantly shortening the seat cushion in the front area on both sides where the thighs usually rest with their front (lower) sections, a considerable reduction in the indentation can be achieved. This results in a change in the behavior of the restoring moment relative to the seat. Figures 1 to 3 However, this does not happen.

[0017] It was also assumed that a similar design for the front edge of the thigh support, as found in the aforementioned printed materials, would achieve a comparable seating experience. However, this assumption proved incorrect, as the situation is different with a saddle seat. Due to the absence of a thigh support, the shorter seat surface is much more noticeable. When leaning back, whether with the entire upper body or by moving the pelvis forward and backward, the edge of the seat surface lifts, creating slight pressure in the buttocks and thigh area. This pressure is often not perceived as unpleasant when first sitting down and moving, but can soon become bothersome during prolonged sitting, especially due to the desired continuous pelvic movement.

[0018] Further investigations have revealed the following, which can be seen from the Figs. 7 and 8 This is explained in more detail below: This is done using a chair with a split seat 4 and 12, as described in detail in the aforementioned WO 2022 / 174 945 A1, in order to illustrate the problem even when considering the lifting of the front edge 11 of the seat, and to demonstrate the general applicability of the invention. The articulated separation point of the two seat parts 4 and 12 was positioned so that it corresponds approximately to the location of the muscle fold between the gluteal and thigh muscles. This separation point is usually located in the aforementioned range between 50 mm and 300 mm from the backrest. This placement largely corresponds to the human musculoskeletal system, so that the movement between the seat parts is hardly or not at all perceived, and certainly not as unpleasant. The arrangement is made of Fig. 7 visible.

[0019] A depiction of the swivel mechanism has been omitted here because it is not necessary.

[0020] The movement of the two seat surface parts 4 and 12 relative to each other occurs around a horizontal normal axis onto the plane of symmetry 10, which is also in the Figures 7 and 8 coincides with the plane of the drawing. Regarding the kinematic connection of the movable seat surface part 12 to the rear seat surface part, reference is made to the aforementioned publications of the applicant, which need not be explained in more detail here as they represent prior art.

[0021] An undesirable aspect of leaning back is that the seat, and especially its front part 12, even with a split seat surface 4, 12, undergoes a noticeable upward movement. This occurs because a moment must be generated to support the user's upper body in the direction of an upright sitting position. Therefore, the horizontal pivot axis 26, which runs perpendicular to the plane of symmetry of the chair (through the central point 9 in a three-axis kinematic system), must be positioned slightly behind the center of gravity of the seated person (thus generating the restoring moment). The horizontal position of the center of gravity is indicated by the tip of arrow "A", and the lever arm by the double arrow.Due to these geometric conditions (positioning of the seat surface end and the pivot axis), the front edge of the seat 11 is located significantly in front of the pivot axis 26, which, despite the change in angle between the seat parts 4, 12, leads to a noticeable lifting of this edge 11 when leaning back, as a comparison of the . Figs. 7 and 8 shows.

[0022] A less significant, but nonetheless noteworthy effect is that when leaning back (with a rigid upper body), the center of gravity lies above the pivot axis 26. Although this is not directly related to the seat edge 11, the effective radius (the distance of the center of gravity to the pivot axis 26) decreases when leaning back; the lever arm shortens to the length of the double arrow B. This reduces the restoring moment when leaning back, resulting in the sitter feeling less and less pressure from the backrest, as can also be seen from the comparison of the Figs. 7 and 8This is evident. This can cause discomfort in sensitive individuals. Ideally, this contact pressure (= restoring torque) would remain (at least approximately) constant or, better yet, increase across the entire range of motion. However, since the pivot axis should at least approximately coincide with the instantaneous center of gravity of the human hip during walking, it cannot be raised so high that it lies at the (unindicated) height of the center of gravity. Only in this way could the decreasing behavior of the torque when leaning back be geometrically compensated.

[0023] It has thus been shown that when swivelling the seat surface 4 together with the backrest 5 backwards, it is desirable, on the one hand, to generate a return moment into the upright sitting position that is noticeable to the user, and on the other hand, to avoid swivelling the front edge 11 of the seat surface 4, 12 in the area of ​​the thighs to the same extent as the seat surface as a whole, in order to reduce or, if possible, avoid the constriction in the knee area of ​​the thighs.

[0024] A key insight upon which the invention is based is that it is desirable to position the horizontal axis of the pivot (and thus usually also the central point) as far forward as possible, since this reduces or even eliminates the lifting of the front edge of the seat surface when leaning back. This applies to all types of seats—classic, split, tractor, or saddle-like—and the comb-shaped seats described below as a novel feature, but it leads to a significant (or even complete) loss of restoring torque. The further insight that leads to the solution is the provision of a spring element that acts as an energy storage device when leaning back, thus providing this restoring torque.

[0025] The spring element can take on a wide variety of shapes and be placed in a wide variety of locations, as will be explained below.

[0026] The invention thus solves the problems by creating a corresponding restoring torque when the seat surface pivots. This can be achieved either via spring elements in the seat surface, including their special design, and / or separately arranged spring elements between the base and the seat surface.

[0027] The invention is explained in more detail below with reference to the drawing. The drawing(s) show: the Fig. 9 a variant according to the invention in a kind of exploded view, in a view corresponding to the Fig. 1 , the Figs. 10 and 11 the situation when leaning back on a seated piece of furniture according to that of the Fig. 9 , the Figures 12 to 15 another variant in different views with details, and the Figs. 16 and 17 Another variant, in section along the plane of symmetry and with a detail.

[0028] To further explain the aforementioned problem of the weakening restoring torque when swiveling the chair, we will refer again to the Figs. 7 and 8 referred to. A split seat surface 4 is shown, which is connected to the backrest 5 and the three-axis kinematics 3 (or another suitable kinematics, in the Figures 7 and 8 (not shown) connected, rear part continues to bear the reference numeral 4, while the front part of the seat surface, which is movable with respect to this part 4, bears the reference numeral 12.

[0029] In Fig. 7 The focus of the combination is: the swiveling portion of the user plus the swiveling portion of the furniture, indicated by the letter S. In connection with Fig. 8The following is evident: When leaning back, the horizontal distance of the center of gravity S from the pivot axis 26 changes (decreases) from "A" to "B" and causes only a small, and moreover decreasing, restoring moment, but in particular no restoring moment that increases when leaning back or even remains constant, which, as mentioned above, would be desirable.

[0030] A first variant according to the invention for solving the problems mentioned above is described in the Figs. 9-11 depicted, views similar to the Figures 1 to 3 or 4 to 6 Here, the seat surface 4, like a comb, has incisions or elongated recesses in the front area that are parallel to the plane of symmetry 10 (drawing plane in Fig. 10The seat is divided, with the side sections 15, each mounted separately on (or integrally with) the seat surface 4, being elastic and thus resilient, deformable upwards and downwards. This allows for significantly easier lowering in the thigh area of ​​the user and thus results in considerably less constriction when leaning back. The central section 16, in contrast to the side sections 15, is considerably firmer, almost rigid, as is typical for office chairs. A support, designed as a comb-shaped seat surface 17, further reduces constriction at the front edge 11 in the illustrated embodiment, thus providing a comfortable enhancement.

[0031] The Figs. 10 and 11 The images show the situation when sitting upright or leaning back on such a piece of furniture. It is noticeable in Fig. 11the curvature of the lateral, springy part 15 facing the viewer, thus a spring device, of the seat surface.

[0032] Furthermore, the change in the horizontal position of the (undefined height of the center of gravity S, of which only one position is shown in front of the central point 9 when sitting upright and behind the central point 9 when leaning back) is clearly visible. From the position whose horizontal distance to the pivot axis (defined by the central point 9) in Fig. 10 If the position marked A is entered, this changes when leaning back to distance B. Fig. 11However, it lies on the opposite side and therefore no longer provides a restoring moment. As can be seen from the shape and position of the lateral, springy parts 15 of the seat surface, these are elastically deformed (spring action) and therefore press down from below, but over a flat area, without cutting into the front edge, onto the user's thighs and vice versa. This supporting force of the user leads, via the comb-shaped seat surface 28, to an uprighting moment on the backrest 5, independent of the horizontal position of the center of gravity with respect to the pivot axis, and thus to the desired uprighting moment.

[0033] This means that, depending on the interpretation of the geometry, when the empty chair is leaned back (e.g. by hand, from "outside"), it may remain in the resting position, while when it is leaned back with and by a user sitting on the seat, it is brought back into the upright position.

[0034] This shows how closely related the problems of constriction and the problems of straightening are in kinematic, static and also dynamic terms; which one receives more attention is a matter of the opinion of the users and designers.

[0035] The Figures 12 to 15 show a perspective view, a detail of the Fig. 12 , a section along the plane of symmetry and another detail. They show a piece of furniture similar to that of the Figures 4 to 6In this seating element, a three-axis kinematic mechanism 3 (partially shown for clarity) is provided between the base 2 and the seat 4. This allows the seat to perform a spherical movement around the central point 9 thus formed, and consequently also a pivoting movement around the virtual transverse axis. The seat 4 is rigidly but resiliently connected to a backrest 5. A spring-loaded kinematic mechanism is used to generate the desired restoring torque. In the illustrated embodiment, this mechanism is constructed as follows: The rear end of a counter-spring 21, designed as a leaf spring, is rotatably arranged at the front of the base 2 about a rear axis 25 that is perpendicular to the plane of symmetry. The front end of the counter-spring 21 is rotatably connected to the upper end of a leaf spring 19 about an intermediate axis 20 that runs parallel to the rear axis 25.Its lower end, in turn, is rotatably mounted in a bracket 23 fixedly connected to the seat surface 4 about a leaf spring axle 18 which is also parallel to the rear axle 25. Furthermore, at least one (possibly pre-tensioned) torsion spring 24 is located in the bracket 23. Fig. 13 ) provided, which the leaf spring 19 in the view of the Fig. 15 The spring is subjected to a clockwise torque. When leaning back, this torsion spring is (possibly further) tensioned, thus generating a restoring torque towards the upright seating position, which increases with further backward tilting.

[0036] The spring element, the torsion spring 24, is thus provided between the base 2 and the seat surface 4, whereby, of course, with knowledge of the invention and especially this embodiment of the invention, numerous variants of the design are available. For example, the torsion spring can be provided at the intermediate axis 20 or, if no spherical movement is intended, it can be replaced or supplemented by a compression spring between the axes 18, 20 and / or a tension spring between the axes 20, 25.

[0037] Furthermore, in Fig. 15A block projecting downwards from the seat surface, without a reference numeral, serves as a movement stop between the seat surface 4 and the clamping block 22. However, with knowledge of the invention, this block can easily be replaced by another measure. The leaf spring 19 and the counter spring 21 act only as rods when the seat surface 4 moves about the pivot axis. However, since, as explained above, spherical movement is also to be permitted, they are twisted during such spherical movement with a component "outside" the transverse axis, which would not be possible with "rigid" rods. This torsion also produces the desired righting moment about the respective instantaneous axis during spherical movement, while the torsion spring(s) 24 provide the restoring moment about the transverse axis.

[0038] If no spherical movement is intended, rigid rods can be used instead of the leaf springs 19, 21.

[0039] Naturally, this variant also works with a comb seat surface 28, or with a tractor seat surface, or a completely state-of-the-art, one-piece seat surface that also firmly supports the lower legs, or a split seat surface as in the Figs. 7 and 8 The kinematics that can be used for this purpose have been shown and are explained in detail in the applicant's two publications, so that, with knowledge of the invention, there is no problem for a person skilled in the art to use it in the present case as well.

[0040] The Figs. 16 and 17 show one of the Figures 12 to 15A similar variant with a standard seat 4 and backrest 5 exists, in which the base 2 is connected in its front area to the seat 4 in the area of ​​its front edge 11 by means of a (possibly pre-tensioned) tension spring 27. When leaning back, this tension spring is (possibly further) tensioned, thus generating a restoring moment on the seat 4 towards the upright sitting position, which increases with further backward tilting.

[0041] This return mechanism can of course also be combined with all the described seat surface variants.

[0042] The illustration and explanation of armrests have been omitted here because they are unrelated to the invention. It should merely be noted that all types can be used, whether connected to the base 2, the seat 4, or the backrest 5. The backrest, in turn, need not be connected to the seat in the manner shown (or any other); all types of connections to the base (whereby the spring elements described here then act on the backrest), as known from the prior art, can also be used. This does not conflict with the invention.

[0043] The invention, in its various versions, can be used with all types of kinematics, not just the illustrated three-axis kinematics, provided that a base 2 and a seat surface 4 are connected in such a way that this connection provides at least one transverse axis 26 (pivot axis) normal to the plane of symmetry 10 of the seating furniture 1 above the seat surface 4. Whether pivoting about other axes is also possible, in particular about a longitudinal axis lying in the plane of symmetry, horizontally or inclined, as known from standard designs, is irrelevant to the invention.

[0044] The backrest 5 can be articulated to the base instead of the seat, optionally with a spring mechanism. In this case, the spring element provided according to the invention is inserted appropriately into a kinematic device that is provided between the seat element and the backrest in such designs.

[0045] As shown, the base can have or be mounted on a gas spring and a roller frame; it can therefore be height-adjustable with respect to the contact surface and, if necessary, be spring-loaded and rotatable around the vertical axis of the gas spring.

[0046] The focus was on the presentation and explanation of limiting devices for the various movements (with the exception of the one in Fig. 15 (explained attack) omitted, these are known and notorious from the prior art for a wide variety of applications and designs, so that it is possible for the person skilled in the art, with knowledge of the invention, to make a suitable selection and design for the respective application without lengthy deliberation, let alone original thinking.

[0047] In the description and claims, the terms "front," "back," "top," "bottom," and so on are used in their common sense and with reference to the object in its usual position of use. This means that, in the case of a weapon, the muzzle of the barrel is "front," that the bolt or slide is moved "backward" by the exploding gases, etc. In the case of vehicles, "front" refers to the usual direction of travel. "Direction of travel," when referring to the suspension of a monorail and not the track(s), refers to this direction along the suspension. "Perpendicular to this" essentially means a direction rotated by 90° and running essentially horizontally.

[0048] It should be noted that in the description and claims, terms such as "lower region" of a suspension, reactor, filter, structure, or device, or more generally, of an object, mean the lower half, and in particular the lower quarter, of the overall height; "lowest region" means the lowest quarter, and in particular an even smaller portion; while "middle region" means the middle third of the overall height (width - length). All these terms have their common meaning when applied to the intended position of the object in question.

[0049] In the description and claims, "essentially" means a deviation of up to 10% of the specified value, if physically possible, both downwards and upwards; otherwise, only in the sensible direction. For degree specifications (angle and temperature), this means ± 10°.

[0050] All quantities and proportions, especially those defining the scope of the invention, insofar as they do not relate to specific examples, are to be understood with a tolerance of ± 10%: 11% means, for example, from 9.9% to 12.1%. In terms such as "a feather", the word "a" is not to be understood as a numeral, but as an indefinite article or pronoun, unless the context indicates otherwise.

[0051] Unless otherwise specified, the term "combination" or "combinations" refers to all types of combinations, from two of the components in question to a multitude or all such components; the term "containing" also refers to "consisting of".

[0052] The features and variants specified in the individual embodiments and examples can be freely combined with those of the other examples and embodiments and, in particular, used to characterize the invention in the claims without necessarily including the other details of the respective embodiment or example.

[0053] In summary, the invention and its most important variants and embodiments can be formulated hierarchically as follows: 1. Seating furniture 1 with a base 2 and a seat surface 4, which is pivotable about a horizontal transverse axis 26, located above the seat surface 4, by means of a pivoting device relative to the base 2 between an upright sitting position and a reclined resting position, and with a backrest 5, in particular an office chair, wherein it is provided that at least one spring element 15, 24, 27 is provided which, when the seat surface 4 is pivoted towards the resting position, generates a restoring moment on the seat surface 4 in the direction of the upright sitting position. 2. Seating furniture according to claim 1, wherein it is provided that the backrest 5 is rigidly, optionally resiliently, connected to the seat surface 4. 3.Seating furniture according to claim 1 or 2, wherein it is provided that at least the areas of the leg support of the seat surface 4, viewed from the backrest, end shortly after the ischial tuberosity and optionally a leg support follows forward, which is either articulated to the rear part of the seat surface 4 or is designed without an articulated joint by an elastically mounted leg support. 4. Seating furniture according to any one of claims 1 to 3, wherein it is provided that the spring element 15 has or consists of resilient lateral parts of a comb-like seat surface 28, which are elastically deformed when leaning back. 5. Seating furniture according to claim 4, wherein it is provided that the elastic deformation is caused by the downward pressure of the thighs of the user of the seating furniture. 6. Seating furniture according to any one of claims 1 to 3, wherein it is provided that the spring element 24 is provided between the base 2 and the seat surface 4. 7.Seating furniture according to claim 6, wherein the rear end of a counter spring 21 designed as a leaf spring is rotatably arranged on the front of the base 2 about a rear axis 25 which is normal to the plane of symmetry 10, the front end of which is rotatably connected about an intermediate axis 20 which is parallel to the rear axis 25 to the upper end of a leaf spring 19, the lower end of which is in turn rotatably mounted about a leaf spring axis 18 which is also parallel to the rear axis 25 in a bracket 23 fixedly connected to the seat surface 4, wherein at least one torsion spring 24, optionally pre-tensioned, is provided about at least one of the axes 19, 20. 8.Seating furniture according to claim 6, wherein the rear end of a rod is rotatably arranged on the front of the base 2 about a rear axis 25 which is normal to the plane of symmetry 10, the front end of which is rotatably connected about an intermediate axis 20 which is parallel to the rear axis 25 to the upper end of another rod, the lower end of which is in turn rotatably mounted about an axis also parallel to the rear axis 25 in a bracket 23 fixedly connected to the seat surface 4, and wherein at least one, optionally pre-tensioned, torsion spring 24 is provided about at least one of the axes 19, 20.Seating furniture according to claim 6, wherein the rear end of a rod is rotatably arranged on the front of the base 2 about a rear axis 25, which is normal to the plane of symmetry 10, the front end of which is rotatably connected about an intermediate axis 20, which is parallel to the rear axis 25, to the upper end of another rod, the lower end of which is in turn rotatably mounted about an axis also parallel to the rear axis 25 in a bracket 23 fixedly connected to the seat surface 4, and wherein a compression spring is provided between the axes 18, 20 and / or a tension spring is provided between the axes 20, 25. Seating furniture according to claim 6, wherein one end of a tension spring 27 is attached to the front of the base 2, the other end of which is connected to the seat surface 4 in the region of the front seat edge 11 below the seat surface 4.Seating furniture according to one of claims 1 or 3, wherein the backrest 5 is articulated, optionally resiliently, connected to the base 2, and the spring element is provided between the seat surface 4 and the backrest 5. Reference symbol list:

[0054] 01 Armchair, Chair 02 Base 03 Three-axis kinematics 04 Seat surface 05 Backrest 06 Base frame 07 Contact surface 08 Vertical axis 09 Center point 10 Plane of symmetry 11 Front edge 12 Movable seat surface section 13 Tension spring 14 Tractor seat surface 15 Side sections 16 Middle section 17 Comb seat surface 18 Leaf spring axis 19 Leaf spring 20 Intermediate axis 21 Counter spring 22 Tension block 23 Bracket 24 Torsion spring 25 Rear axis 26 Transverse axis 27 Tension spring 28 Comb seat surface

Claims

1. Seating furniture (1) with a base (2) and a seat surface (4) which can be pivoted about a horizontal transverse axis (26) located above the seat surface (4) between an upright sitting position and a reclined resting position by means of a pivoting device relative to the base (2), and with a backrest (5), in particular an office chair, characterized by that at least one spring element (15, 24, 27) is present which, when the seat surface (4) pivots towards the rest position, generates a restoring moment on the seat surface (4) in the direction of the upright sitting position.

2. Seating furniture according to claim 1, characterized by the fact that the backrest (5) is firmly, possibly with springs, connected to the seat (4).

3. Seating furniture according to claim 1 or 2, characterized by the fact thatat least the areas of the leg support of the seat surface (4), viewed from the backrest, end shortly after the ischial tuberosity and are optionally followed forward by a leg support which is either articulated to the rear part of the seat surface (4) or is designed without an articulated joint by an elastically mounted leg support.

4. Seating furniture according to one of claims 1 to 3, characterized by the fact that the spring element (15) has or consists of resilient lateral parts of a comb-like seat surface (28) which are elastically deformed when leaning back.

5. Seating furniture according to claim 4, characterized by the fact that The elastic deformation is caused by the downward pressure of the user's thighs on the seat.

6. Seating furniture according to one of claims 1 to 3, characterized by the fact that the spring element (24) is provided between the base (2) and the seat surface (4).

7. Seating furniture according to claim 6, characterized by the fact thatThe rear end of a counter spring (21) designed as a leaf spring is arranged on the front of the base (2) rotatably about a rear axis (25) which is normal to the plane of symmetry (10), the front end of which is rotatably connected about an intermediate axis (20) which is parallel to the rear axis (25) to the upper end of a leaf spring (19), the lower end of which is in turn rotatably mounted about a leaf spring axis (18) which is also parallel to the rear axis (25) in a holder (23) fixedly connected to the seat surface (4), wherein at least one torsion spring (24), optionally pre-tensioned, is provided about at least one of the axes (19, 20).

8. Seating furniture according to claim 6, characterized by the fact thaton the front of the base (2), rotatably about a rear axis (25) which is normal to the plane of symmetry (10), the rear end of a rod is arranged, the front end of which is rotatably connected about an intermediate axis (20) which is parallel to the rear axis (25) to the upper end of another rod, the lower end of which is in turn rotatably mounted about an axis also parallel to the rear axis (25) in a holder (23) fixedly connected to the seat surface (4), and that at least one torsion spring (24), optionally pre-tensioned, is provided about at least one of the axes (19, 20).

9. Seating furniture according to claim 6, characterized by the fact thaton the front of the base (2), rotatably about a rear axis (25) which is normal to the plane of symmetry (10), the rear end of a rod is arranged, the front end of which is rotatably connected about an intermediate axis (20) which is parallel to the rear axis (25) to the upper end of another rod, the lower end of which is in turn rotatably mounted about an axis also parallel to the rear axis (25) in a bracket (23) fixedly connected to the seat surface (4), and that a compression spring is provided between the axes (18, 20) and / or a tension spring is provided between the axes (20, 25).

10. Seating furniture according to claim 6, characterized by the fact that at the front of the base (2) one end of a tension spring (27) is attached, the other end of which is connected to the front edge of the seat (11) below the seat surface (4).

11. Seating furniture according to one of claims 1 or 3, characterized by the fact thatthe backrest (5) is articulated, possibly with springs, connected to the base (2), and the spring element is provided between the seat (4) and the backrest (5).

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