Seating furniture having a longitudinal axis above the seating surface

Abstract

The invention relates to a seating element (1) with a plane of symmetry (62) and with: - a lower part (2) which has or is formed a base (3) in its upper region, and - a seat surface (4) which is movably connected to the base (3) by means of a kinematic mechanism (22) about a longitudinal axis (63) which lies at least largely above the seat surface (4), is inclined forward and downward by up to 75° (preferably 45° ± 20°) relative to the horizontal, and which, in its rest position, lies in the plane of symmetry and may optionally be virtually formed. The invention is characterized in that a return mechanism (23) with an energy storage device (6) is provided between the base (3) and the seat surface (4), which exerts a return torque on the seat surface (4) when the seat surface (4) is deflected about the longitudinal axis (63) from its rest position.

Description

[0001] The invention relates to a seating furniture with a seat and a vertical plane of symmetry, wherein the seat is pivotable by means of a kinematic mechanism about a longitudinal axis relative to a base of the seating furniture. The longitudinal axis, in its rest position, lies within an angular range of 5° rearward and downward to 75° forward and downward, preferably 45° ± 30° forward and downward, and most preferably 45° ± 20° forward and downward in the plane of symmetry and at least predominantly above the seat. The longitudinal axis can also be virtual, for example, formed by a spherical mounting of the seat about a pivot point above the seat, which allows rotation about "all" axes. For the sake of simplicity, the following text will mostly refer to the "longitudinal axis", in most cases this is inclined forward at an angle of 45° ± 30° (or ± 20°) to the horizontal, but a greater inclination up to 75° (technically precise, not mathematically) is also quite possible.The kinematics that cause this are explained in detail in the inventor's / applicant's publications discussed below and therefore do not require further explanation here.

[0002] Regarding the term "plane of symmetry," it should be noted that this only applies with certain caveats, because while the individual components and handles of seating furniture, such as office chairs, are indeed unilateral, a plane of symmetry does exist for the seat and, if present, the backrest and armrests. This plane runs vertically when the chair is at rest and pivots along with the seat. It is this plane that will be considered the plane of symmetry in the following discussion.

[0003] Regarding the term "seat surface," it should be noted that it can be divided, with the two parts being pivotable about a horizontal axis perpendicular to the plane of symmetry, and the rear part being rigidly or flexibly connected to a backrest. In this case, the kinematic mechanism can be connected either to the backrest and thus to the rear part of the seat surface, or to the front part. The seat surface, divided or undivided, can also be upholstered; this does not affect the position of the longitudinal axis "above" the seat surface. In extreme cases, it lies above the seat surface covering. If, in an extreme tilt, the front part of the longitudinal axis comes to lie below the seat surface, then, in the resting position, the larger portion of the longitudinal axis that lies within the irregular cylinder formed by the outline of the seat surface in the direction of the vertical is located above the seat surface.

[0004] Such a piece of seating furniture is known, for example, from EP 1 090 568. This document proposes mounting a seat on an at least approximately spherical base using spherical or convex rollers. The instantaneous pivot point, the instantaneous center of rotation, which is therefore not fixed relative to the base, lies approximately at the user's chest height, but can also be lower. Due to this position, the center of gravity of the user-(movable part of the) furniture combination is always below the instantaneous center of rotation, thus keeping the seat and user in an upright, stable, "resting" position.

[0005] EP 2 381 816 discloses various swiveling seating furniture, some with their pivot point in the floor area, some just below the seat surface. Above the seat surface, specifically in the thoracolumbar spinal region, the location is mentioned as preventing rotation around this axis while sitting, thus avoiding degenerative effects from prolonged sitting. Only one example with a precisely horizontal, physically defined longitudinal axis is given.

[0006] Seating furniture is known from DE 40 06 608 and EP 780 073 in which longitudinal axes for the seat surface are provided directly below the seat surface.

[0007] From WO2016 / 042127 of the applicant, a seating furniture is known in which a longitudinal axis is virtually formed above the seat surface in the form of a spherical bearing. The kinematics are as follows: At the base, a sequence of three mutually pivotable, serially arranged arms is formed, the last of which is fixedly connected, directly or indirectly, to the seat surface, and whose three pivot axes intersect at a single point, the central point, often only in a central region. This central point lies above the seat surface, preferably in the pelvic region of the presumed user, and particularly preferably approximately at the height of the user's center of gravity in the plane of symmetry of the seating furniture. Since spherical movement about this central point is possible, movement about the (virtual) longitudinal axis is possible, without being predetermined or preferred.The three-arm kinematics used, often and actually more accurately referred to as three-axis kinematics, is already known in itself from WO 2012 / 123102 by the same inventor.

[0008] A completely different type of seating furniture with a "real" longitudinal axis is known from EP 3 890 558 B1. In this design, a cantilever extending obliquely upwards is rotatably mounted on a vertical support. A swivel arm is slidably mounted on the cantilever and can also pivot about a rotation axis lying in a vertical plane, corresponding to its longitudinal axis. The seat is then appropriately attached to this swivel arm. The rotation axis / longitudinal axis forms an angle of approximately 65° with a horizontal plane and lies almost entirely below the seat. A commercially available chair built according to this principle, belonging to the patent holder, has a rotation axis / longitudinal axis at an angle of approximately 75° to the horizontal plane. This axis lies largely above the seat, and the pivot point formed with the vertical rotation axis is located well above the user's center of gravity, thus always forcing the user into a stable, upright, resting position.

[0009] In both cases, a rotational movement is only possible in the manner described; a typical "simply leaning back" is impossible.

[0010] Due to their spherical mounting, the seating furniture with a virtual longitudinal axis can also perform pivoting movements about a transverse axis and rotational movements about the vertical axis (and, due to the nature of the spherical mounting, about any other assumed axis as well), but this is irrelevant in the context of the invention. It is equally irrelevant to the invention whether a backrest and / or armrests are provided and how these are mounted / attached to the seat surface.

[0011] Regarding the use of such seating furniture, hereinafter usually referred to as "chair" or "office chair," the following should be noted: We are confronted almost daily with headlines warning of the health risks of sitting. Articles such as "Sitting Makes You Sick" from Norddeutscher Rundfunk (2022), "Sitting Is the New Smoking" by Juliet Starrett (2016), "Lack of Exercise Makes Millions Sick" from Tagesschau (2022), or "Those Who Sit Longer Die Sooner! Get Out of the Sitting Trap" from MDR (2022) can be found in both digital media and the traditional press. The World Health Organization (WHO) also emphasizes the importance of regular exercise and recommends standing, walking, or playing sports more often (2020).

[0012] For decades, physicians and experts have warned of the consequences of lack of exercise and prolonged sitting, including back pain (Lis, Black, Korn, & Nordin, 2007), shortness of breath and digestive problems (BAuA, 2011), as well as an increased risk of type 2 diabetes and heart attacks (Latza, Bucksch & Wallmann-Sperlich, 2020). These can lead to impaired well-being (Atkin et al., 2012), promote mental illness (Kilpatrick et al., 2013) and contribute to depression (van Uffelen et al., 2013).

[0013] Despite repeated warnings, the number of illnesses attributable to excessive sitting continues to rise, as shown in health insurance reports (e.g., DKV Report, 2021). In Germany, people sit for an average of around 8.5 hours on weekdays, which is one hour more than in 2018, while young adults (18 to 29 years old) reach the peak at 10.5 hours. This contributes to an increase in musculoskeletal disorders, which, along with mental health issues, are a major cause of work absences (Techniker Krankenkasse, 2022).

[0014] The design of our workplaces contributes to this problem. Approximately 59% of employees in Germany spend at least half of their working time in an office, mostly sitting (German Association for Office and Workplace Equipment, 2020). Work at workbenches and in production also often involves sitting. The short break to go to the coffee machine offers little compensation for the physical strain, and even leisure time is often lacking in active recreation. List of Figura

[0015] Since the following section explains not only the invention but also the prior art and the anatomical background using figura, they are listed here, showing: The Figs. 1a-d in four separate illustrations the movement of the hip in and across the sitting direction on a seat surface with an instantaneous center of gravity at the level of the user's upper abdomen, which Figs. 2a-dthe movement of the entire upper body when sitting freely, analogous to Fig. 1 , the Figs. 3a-d a seating furniture according to the invention with a simple spring storage device for building up a counter-moment, which Figs. 4a-e a seating furniture according to the invention with an adjustable spring storage system, which Figs. 5a-d a simple variant in different inclination states, which Fig. 6 an enlarged view of the Fig. 5b , the Fig. 7 a detail of the Fig. 6 , the Fig. 8a-d one variant and the Fig. 9a-c a variant with a one-piece seat and a 55° steep longitudinal axis, which Fig. 10a-c a variant with a split seat and a longitudinal axis running at a 55° angle, and the Figs. 11a.b and 12a,b analogous variants to those of Figs. 9 and 10 with a 70° steep longitudinal axis. Background of the invention's task

[0016] Previous solutions have proven largely ineffective and have not been able to significantly reduce the aforementioned health problems. Therefore, we advocate the approach that necessary movements must occur during working hours, and thus while seated. The office chair must allow for a wide range of motion to relieve and stimulate the intervertebral discs, which promotes nutrient supply and maintains spinal health. Furthermore, the back should be supported by a suitable backrest to prevent the back muscles from being subjected to prolonged static strain. Why existing active chairs are insufficient

[0017] Many chairs on the market allow for hip tilting, but do not meet the requirements for a healthy sitting posture. Criticisms include the fact that the pivot point is located below the seat and movements do not follow human anatomy. This can make concentrated work difficult, as the head and upper body move along with the chair, requiring constant refocusing of the eyes. Furthermore, working with texts or spreadsheets can be impaired by these movements. Requirements for an optimal ergonomic chair

[0018] An ideal ergonomic chair should mimic the natural hip and lumbar movement that occurs when walking, while simultaneously keeping the head and shoulders in a stable position. In healthy adults, this rolling, pivoting motion during walking occurs around an axis angled approximately 45° forward and downward, passing through the area of ​​the ninth to twelfth, preferably the eleventh, thoracic vertebrae. The angle depends on various factors, including age, general and current physical condition, pace of movement, and more, so ranges of 45° ± 30°, at least ± 20°, and especially ± 10° or 5° are advantageous.

[0019] These areas are advantageous to apply to seating depending on the user's habits and physical condition. Positioning the user's center of gravity above the central point is highly beneficial, and it is necessary for the majority of the longitudinal axis within the seat cylinder to be located above the seat surface.

[0020] When sitting, your feet should be firmly planted on the floor to ensure a stable posture. Traditional chair designs that use pivot points beneath the seat do not adequately mimic the dynamics of human movement.

[0021] Scientific studies, including the work of R. Kuster (Physiological axis of movement for the seat of a dynamic office chair - PMC (nih.gov)) and the unpublished dissertation by Mark Bührer, have found that the ideal pivot point is located at the level of the upper abdomen, near the eleventh thoracic vertebra (thus in the region of the ninth to twelfth, preferably at the level of the eleventh thoracic vertebrae). These findings emphasize the importance of seating furniture that promotes the natural movements of the human body while sitting and are reflected in Fig. 1a-d , illustrating the movement of the hip in and across the sitting direction around a momentary center of gravity at the level of the upper abdomen.

[0022] The Fig. 1The four individual illustrations show in detail the specific kinematics of the hip movement of a user 19 on the seating furniture 1, a chair with a split seat 4, the rear part of which is a fixed or resilient part of the backrest 11, by means of a representation of the user's bones. Regarding such furniture, it should be noted that a lower part of the furniture (chassis, gas spring, etc.) (not shown here) is connected to the backrest via a kinematic mechanism, and the actual (front) seat surface is pivotably connected to the rear seat surface part, which is fixedly or resiliently connected to the backrest, about a transverse axis. A further kinematic mechanism is responsible for the relative position (angular position) between these two parts, as described in detail in WO 2022 / 174945 of the applicant.

[0023] Arrow 20 (approximately horizontal and lying in the plane of symmetry 62 of the seating element 1, which naturally does not take into account details such as the mechanics of the kinematics, etc.) points to the part of the spine where the bending can be considered concentrated. Arrow 20 thus also symbolically represents, cum sala granis, the respective component of movement around the axis it indicates. Fig. 1a Figure 11 shows upright sitting with "forceless" contact with the backrest; the knee also represents this. Fig. 1b The forward tilting of the upper body and the changed leg position are visualized; in the depicted construction of the seating furniture 1, the position of the backrest 11 and the relative position of the two parts of the seat surface 4 change. The change in the curvature of the spine is recognizable.

[0024] The lower partial figures c and d illustrate the lateral tilting of the pelvis to the left and right, respectively. This is a precisely isolated movement of the pelvis, again indicated by an arrow, arrow 21, this time running approximately horizontally in a transverse direction and again pointing to the symbolic "flexion point" of the spine. The tilt of the pelvis follows the defined axis of rotation of the chair and thus remains stationary with respect to the seat 4; the pelvis therefore moves synchronously with the seat 4 and the backrest 11, while the shoulders and head of the seated person remain relatively stable in space.

[0025] This (dual) movement dynamic of the pelvis on the chair, characterized by specific angles around the axis(s) of rotation in the three spatial dimensions, mimics the natural walking motion of humans. This correlation is demonstrated in the study "Patterns of spinal motion during walking" by Jack Crosbie, Roongtiwa Vachalathitib, and Richard Smith, published in December 1994. The study identifies consistent movement patterns: "We found consistent patterns within and between the segments and movements, with an apparent trailing movement of the trunk after pelvic displacements. This suggests that the spinal movements associated with walking are linked to the primary movements of the pelvis and lower limbs." This observation by the authors was corroborated by subsequent metrological investigations by R. Kuster.

[0026] The Figs. 2a -dThe illustrations above show, only as a counter-example and for clarification. Figs. 2a,b The situation is described as follows: when the user 19 swivels sideways, the movement of the seat 4 and the backrest 11 remains "immobile". For this reason, instead of an arrow, only a line was drawn to the now straight spinal area.

[0027] The Fig. 2c indicates that the user leans more strongly against the backrest than in Fig. 1a , which can also be seen from the relative position of the two parts of the seat surface 4 in comparison. Fig. 2d Finally, to complete the picture, the fully reclined position is shown.

[0028] Based on these findings, the inventor developed a special kinematic mechanism that allows the construction of a chair whose pivot point—following scientific recommendations—lies in the upper abdomen, above the seat. This enables movement around all three pivot axes around this central point without the need to forgo a backrest or armrests, as described in the aforementioned WO2016 / 042127. Furthermore, in one embodiment of this kinematic mechanism, lifting of the front edge of the seat can be avoided, as can be seen in the applicant's WO2022 / 174945. This patent also shows, particularly in Figures 16a-l, the various possible orientations of the longitudinal axis, which is designated by reference numeral 16.

[0029] Following development, prototypes of these chairs were manufactured and further optimized over a period of two years. These prototypes were made available to individuals with musculoskeletal disorders. The feedback from these test subjects was overwhelmingly positive. Some experienced a noticeable reduction in pain after only a short period of use. After several months, many test subjects reported a significant improvement or even a complete disappearance of their symptoms. The conditions studied included lower back pain, hip pain, sacroiliac joint dysfunction, and post-operative care following spinal disc surgery. Although the medical benefits still require more extensive studies, the feedback received so far suggests that chairs of this design offer significant potential for alleviating health problems resulting from a lack of movement during sedentary work. The problem

[0030] Unfortunately, it has also become apparent that many participants find it difficult to feel secure in a chair with this type of movement. It can easily take several weeks for this insecurity to lessen or disappear. Some participants completely rejected this movement. This was especially true, firstly, when the physical limitation was not yet very pronounced and the level of discomfort was not yet high enough to accept this adjustment period. Secondly, it was also true for patients who had recently undergone surgery, particularly on their intervertebral discs. Understandably, these patients feared that their situation could worsen and were consistently unwilling to accept this unfamiliar movement.

[0031] The inventor spent a long time considering the underlying reasons. Since the test subjects reported that they got used to the movement after a while, but also that some actually felt nauseous in the chair during the first few hours, it was initially assumed that it was simply a problem with the vestibular system, which had to compensate for the hip movement in combination with a stable head position. Because the hip movement corresponds to a walking motion, and humans are accustomed to the head moving forward while walking, this was long considered the most likely explanation.

[0032] There was, in fact, a second approach. This was based on the observation that this insecurity significantly decreased or disappeared completely as soon as the arms were resting on the desk, for example, to use a computer keyboard. It was thus concluded that this is all related to the person's current movement. If the person moves on the chair as if walking, i.e., pivots or rotates their hips around the chair's center of gravity, the insecurity disappears. However, if the same subject sits freely in the room on the chair, i.e., moves their arms freely, the insecurity returns.

[0033] Therefore, the movement in the two situations was examined more closely: As mentioned, at the desk, while operating the PC, the arms rest on the desk and the hips move – thus, all moving mass points below the chair's pivot point are in stable equilibrium. The person feels secure. However, as soon as the person sits freely, they tend to move their entire upper body rather than the chair. Since not only the pelvis and part of the spine move with the seat, but also the body, including the shoulders, head, and arms, remains relatively rigidly attached to the chair, the center of gravity of the moving mass shifts upwards. The center of gravity then lies above the pivot point (the longitudinal axis, the central point) of the chair – creating an unstable equilibrium that makes the person feel insecure. This is in Figs. 2a-d depicted, which shows the movement of the entire upper body when sitting freely, analogous to Fig. 1 shows. The search for a solution:

[0034] In developing the solution, the chair's pivot point was initially adjusted (shifted upwards) so that the user's center of gravity remained in stable equilibrium (under the longitudinal axis or central point) even during rigid upper body movements (this resulted in a situation similar to the office chair sold by Bergardi mentioned above). While this adjustment reduced the instability experienced by the test subjects, it created a new problem: a wobble in the shoulder and head area, similar—though less pronounced—to that experienced with a pivot point (longitudinal axis) located below the chair surface. This was because the chair's pivot point did not coincide with the physiological pivot point of the pelvis, even though it was shifted downwards in the opposite direction. Therefore, this adjustment was not a satisfactory solution, as it solved one problem while simultaneously creating another.

[0035] To overcome this dilemma, the possibility of applying a counter-moment was considered. This would allow the chair's pivot point (longitudinal axis) to remain close to the physiological pivot point of the pelvis, while simultaneously generating a moment opposing the unstable equilibrium, thus bringing the system—the chair or its seat—into a stable equilibrium. A critical point with this solution, however, was that the counter-moment would also act during purely pelvic movements, thus opposing the test subject's movement. A key characteristic of the chair, however, is its ability to respond to pelvic movements with great ease, so this effect was viewed critically.

[0036] Our tests showed that test subjects performed up to 60 pelvic movements per minute, highlighting the chair's mobility. This effect should not be lost, as the continuous movement stimulates metabolism and the cardiovascular system, which, in addition to positive effects on the musculoskeletal system, also improves the user's concentration and productivity and suggests further health benefits. Despite this challenge, the decision was made to implement a simple spring mechanism to investigate the effects more closely. Such a chair, according to the invention, with a simple spring storage system for generating a counter-torque, is described in Figs. 3 -d depicted.

[0037] The Figs. 3a-dFigure 22 shows (without regard to seat height) a seating element 1 with a lower part 2, supporting or forming a base 3, and a kinematic mechanism provided between the base 3 and an (undivided) seat 4, collectively designated 22, and a backrest 11, which is elastically connected to the seat 4. The kinematic mechanism 22 provides a central point 5 around which the seat is spherically movable, and a longitudinal axis 63 is also formed in the sense explained above.

[0038] This kinematics 22 corresponds to the kinematics detailed in WO2016 / 042127 of the applicant and in WO 2012 / 123102 of the inventor and therefore does not require further description here (a brief explanation is provided in Fig. 5 given).

[0039] The essential and new feature is that a return mechanism 23, adjustable in its effect, is provided between the base 3 and the seat surface 4, which is located in the Fig. 3cIt is shown in the installed state, without the sleeve for the springs, to show them, while the Fig. 3d An exploded view illustrating the construction is shown. This reset device 23 is constructed as follows: A flat intermediate plate 24 is pivotally attached to the intermediate plate, rotatable about a primary axis 44 which, in the exemplary embodiment, is approximately horizontal and fixed with respect to the base 3. A flat actuator 25 with a main plane is arranged on the intermediate plate, rotatable about a secondary axis 45 parallel to the primary axis. A spring mechanism 26 is arranged on the actuator 25, rotatable about an actuator axis 46 which, in the illustrated exemplary embodiment, is perpendicular to the main plane of the actuator 25. A rotary arm 27 is further pivotally attached to the actuator 25 about a pivot axis 47 parallel to the actuator axis 46.

[0040] At the free end of the pivot arm 27, a connecting piece 28 is spherically articulated and rigidly connected to the seat surface 4. Instead of this spherical connection, a universal joint can be used, which would then also lock the "internal rotation" about the vertical axis, explained below, without requiring an additional mechanism. This lock is necessary to prevent singularities in the kinematics. Also in the region of the free end of the pivot arm 27, a coupling rod of the spring mechanism 26 is articulated, carrying an adjusting plate 48 at its other end.

[0041] The adjustable spring mechanism 26 comprises two linearly arranged coil springs within a type of tube, which is rotatably mounted in its central section around the actuator axis 46. These coil springs fix the actuating plate 48 of the coupling rod between them. A screw mechanism inside the springs along their axis shortens or lengthens the entire spring length when the actuating knob 49 is turned, thus changing the preload and consequently the restoring force and therefore the restoring torque.

[0042] By moving the seat surface 4 from its rest position, the free end of the swivel arm 27 and thus the point of application of the coupling rod, the rod itself and thus the adjusting plate 48 are moved, thereby inducing a restoring force and thus a restoring torque.

[0043] This approach proved more successful than initially anticipated. To analyze various conditions, a range of springs were tested to determine different restoring torques. The very first test revealed that the spring with the lowest tension was sufficient to achieve the desired effect. The chair provided stability for the test subjects, both during movements of the entire upper body and during isolated pelvic movements, without the spring force being perceived as disruptive. No impairment of the counter-torque on the movement frequency was observed. Subsequently, the mechanism was further developed so that the restoring torque is variably adjustable, which contributes to the desired compactness of the device, particularly important for mass production. One embodiment is described in the Figs. 4a -e, which also show a seating furniture according to the invention with an adjustable spring storage unit.

[0044] The Fig. 4a Figure 1 shows the entire seating unit 1 in perspective view. The seat surface is divided into the actual (front) seat surface 4 and a rear seat surface section 64, which is rigidly, but optionally flexibly, connected to the backrest 11. Armrests 29 are also shown here for illustrative purposes only; these can, of course, be provided in all illustrated embodiments independently of the design of the seat surface, the type of kinematics, and the choice of return mechanism.

[0045] The Fig. 4bFigure 1 shows the mechanism that exists between the movable and height-adjustable base 2, which is also responsible for rotating the backrest 11 and thus the seat 4 about a vertical axis 9, and the seat 4 itself: First, the kinematics 22 already discussed, with its three arms, which are fixed to a base 3 fixed to the base by means of a mounting part 30 and thus (movable about a transverse axis) to the seat 4, and which support these parts. Furthermore, a similarly constructed seat mechanism 31 connects the base 3 to the seat 4, forming its own central point, and is responsible for the relative movement about the virtual longitudinal axis formed by the two central points, as described in the Figs. 1 and 2This is evident. The inclination of the longitudinal axis relative to the horizontal can be determined by means of the independently definable central points. Finally, a return mechanism 23 is provided on the base 3, pivotable about a horizontal axis, the other point of application of which is fixedly connected to the seat surface 4 via a mounting plate 32.

[0046] As the analogous construction of the kinematics 22 for the backrest including the rear seat surface part and the seat surface mechanism 31 for the seat surface 4 shows, it is purely a matter of perspective whether, as in the following, one considers the kinematics 22 or the seat surface mechanism 31 as the "essential" kinematics for the movement of the seat surface 4 relative to the base 3.

[0047] The design and operation of the reset device 23 are described in the Figs. 4c-e visible:

[0048] The following show Figs. 4c and dthe tubular energy storage device 6 and parts of the reset device 23 in section through the axis of the tube: Fig. 4c in the neutral position and Fig. 4d in a clockwise rotated position. The setup is as follows: A handle 50 is rotatably mounted in the base-fixed tube 51. Inside the tube 51, a spring assembly 52 rests against a tube shoulder 53 on one side and is pre-tensioned on the other by a spring plunger 54 with an internal thread. This pre-tension is achieved because a threaded rod 55 is provided, which is rotationally fixed with respect to the tube but axially displaceable, and onto one end of which the spring plunger 54 is screwed. The spring plunger 54 is connected to the handle 50 in a way that is rotationally fixed but axially displaceable, such that when the handle 50 is rotated, the (pre-)tension of the spring assembly 52 changes.

[0049] At the other end of the threaded rod 55, a pin formed from two aligned plates 56 is rotatably attached at its first end about a pivot axis perpendicular to the axis of the threaded rod. At its other end, the pin is pivotally connected to a rotary lever 57 about a pivot axis parallel to it.

[0050] The rotary lever 57 is rotatably attached to the base 3 at its lower end, near the base, about a rotary lever axis 58. The upper end of the rotary lever 57, near the seat surface, is cranked and pivotally carries a first intermediate member about a first pivot axis, a longitudinal pivot axis 59. This intermediate member is pivotally mounted about an intermediate axis 61 ( Fig. 4b ) rotatable, connected to a second intermediate member. This has a second pivot axis, the connecting axis 60, which runs parallel to the longitudinal rotation axis 59 and is thus connected to the seat-fixed mounting plate 32. The rotation about the intermediate axis is, in comparison to the Figs. 4c and 4dIt is easy to see: in both cases the connection plane of the mounting plate 32 runs approximately horizontally, while the rotary lever 57 is oriented once approximately vertically and once at a distinct inclination, which is made possible by the rotation about the intermediate axis 61.

[0051] If the user now changes the position of the seat from the normal position ( Fig. 4c ) moved out, in which the spring assembly 52 has its greatest length, for example into the in Fig. 4d In the position shown, this is transferred as a whole to the spring assembly 52 via the return device 23 and causes a return torque, the magnitude of which is determined by the presetting using the handle 50 and can be regulated.

[0052] This design means that only the movement around the horizontal longitudinal axis of the seating furniture is influenced by a restoring moment.

[0053] The results of the initial tests confirmed the assumption that full adjustability is not strictly necessary. In particular, it is important to prevent users from setting the chair too rigidly, thereby compromising or even negating the system's benefits. For this reason, it was considered to limit the adjustment range so that the spring tension can be adjusted in only one or two steps – possibly by adding or removing an additional spring – which is perfectly sufficient. Another solution as a further example

[0054] The Figs. 5a -d The four illustrations show a seating furniture 1 according to the invention. It has a lower part 2 which, in the illustrated embodiment, rests on the floor 8 without rollers, and has a vertically arranged gas spring 10 on which a base 3 ( Fig. 6The base 3 is height-adjustable and rotatable about a vertical axis 9 relative to the lower part 2. In the following, the base 3 (as in the other embodiments) is considered "stationary" with respect to the actual kinematics 22, since the aforementioned movements between the lower part 2 and the base 3 are all unnecessary for the invention and are in no way related to it.

[0055] The Fig. 6 is an enlarged representation of the Fig. 5b , the Fig. 7A further enlarged section is shown to better illustrate and explain the kinematic structure of the seating furniture: the base 3, as already described, is rotatable about the vertical axis 9. It projects radially outwards, thus forming a base arm 15, and at its outer end, a pivotally attached intermediate arm 16 is mounted. This intermediate arm, in turn, pivotally supports a seat arm (also called end arm 17) at its other end. The three axes (the base axis coincides with the vertical axis 9; the intermediate axis is the axis between the base arm and the intermediate arm; the end axis is the axis between the intermediate arm and the end arm / seat) intersect at a central point 5 (which therefore lies on the vertical axis 9). Since the end arm is rigidly (but possibly resiliently) connected to a seat 4, the seat is freely movable spherically about the central point 5, and with it everything attached to it, in this exemplary embodiment a backrest 11.For the sake of clarity, the illustration of armrests (or a footrest) has been omitted, but a person skilled in the art can easily imagine their installation without inventive effort; indeed, since they are shown in the aforementioned literature, almost without any intellectual exertion is required. Such a seat corresponds to the aforementioned state of the art (three-arm kinematics).

[0056] Regarding the actual invention: As stated above and in Fig. 6As can be clearly seen, to apply a restoring torque to the deflected seat surface 4, one end of an energy storage device 6, in the illustrated embodiment a pneumatic cylinder (gas spring, metal spring), is movably hinged to an arm point 12 on a support arm 7 which is fixed with respect to the base 3. The other end of the energy storage device is hingedly mounted to a mounting point 13 on the seat surface 4. The energy storage device 6, whatever its type, is designed such that it tends to shorten; the force exerted in this way lies in the line connecting arm point 12 and mounting point 13, the line of action 18.

[0057] To better understand the actual invention, the kinematic relationships will be explained before their further elaboration: The seat point 13, as part of the seat surface 4, performs a spherical movement around the central point 5, thus always remaining at the same distance from the central point. The arm point 12, with its base 3a, performs a pure circular movement in a horizontal plane around the vertical axis 9, thus always remaining at the same distance from the central point 5.

[0058] In the resting position of the Fig. 6 (and the Fig. 5b ) the three points: central point 5 - seat point 13 - arm point 12 lie on a straight line, which means that any force exerted by the energy storage device (along its line of action 18) does not exert a moment on the seat surface due to the lack of a lever arm R, regardless of whether it has a preload at the rest length A0 given by this method or not.

[0059] In the following figures and their description, the respective lever arm that is set, the minimum distance of the line of action 18 of the energy storage from the central point 5, is always indicated by "R" regardless of size and position in space and is intended only for illustration purposes.

[0060] If you compare that to the Fig. 5a Considering the position where the seat surface is pivoted to the left (this and all other considerations / explanations are always made from the viewer's perspective unless otherwise stated), it can be seen that the line of action is more inclined relative to the vertical (than in the rest position) and generates a restoring moment for the seat surface 4 with respect to the central point 5 around the horizontal longitudinal axis through the central point 5 (=normal to the plane of the drawing), since the length AL of the energy storage is greater than A0, which necessarily results from the deflection of the seat point 13 from the straight line connection.

[0061] In Fig. 5c is analogous to Fig. 5a the seat surface 4 is pivoted to the right, the line of action 18 of the energy storage device 6 runs (compared to Fig. 5a ) "Beyond" the central point 5, and the length AR is again greater than the rest length A0, which necessarily results from the deflection of the seat point 13 from the straight line. This in turn results in a restoring moment for the seat surface 4.

[0062] The Fig. 5d The figure represents the situation when the seat surface 4 is tilted back around the central point 5, thus around the transverse axis: again the seat point 13 is deflected from the rest position, meaning that the length AH of the energy storage is greater than in the rest position, the course of the line of action 18 results in a distance to the central point 5, which leads to a restoring moment for the seat surface 4.

[0063] To complete the description of the properties and special features of kinematics and the theoretical requirements for it, the following should be stated:

[0064] The three-arm kinematics allow the seat surface 4 (in each of the illustrated embodiments; this kinematics is simply as shown!) to rotate about the vertical axis 9 (internal rotation). This rotation is kinematically unrelated to the rotation of the seat surface 4 with the base 3 about the vertical axis 9 (external rotation)! The former rotation leads to various problems when using the seating furniture because the entire construction, if left unaddressed, is not free of singularities; reference is also made to the fact that the relative angular position of the arm point 12 to the seat point 13 with respect to the vertical axis 9 can no longer be maintained! It is therefore necessary, but also sufficient, to prevent the rotation of the seat surface 4 about the vertical axis 9, insofar as it results from the three-arm kinematics. This is known from the prior art and poses no technical problem for someone skilled in the art.

[0065] An elegant way to prevent this internal rotation is to link the energy storage device 6 via universal joints 14 and not, as might seem obvious at first glance, via ball joints. It must also be ensured that the energy storage device is not rotatable within itself, as is the case with many gas springs, for example. There is a sufficient selection of such rotationally fixed devices available on the market.

[0066] Another of many possibilities for preventing rotation involves using a link chain, as described in the applicant's DE 10 2018 114 207 B3, or one of the mechanisms specified in the applicant's WO 2022 / 174945 A1. When using such a dedicated anti-rotation device, the energy storage unit can be articulated via ball joints, since it is no longer required for the anti-rotation mechanism. Avoiding such a double guide is even advisable to prevent misalignments and blockages caused by unfavorable tolerances or wear.

[0067] In a further development, consideration was given to how these findings could be incorporated into the design of the simplest possible chair. This led to the preferential use of the kinematic elements, which are essential for the chair's function, as energy storage devices.

[0068] This also included a chair with a split seat, Figs. 8a -d , developed, which is constructed according to its own WO2022 / 174945 and whose front seat area, the actual seat surface 4, has four degrees of freedom. Two of these degrees of freedom were balanced with torsionally flexible elements. These make it possible to generate the required counter-moment and simultaneously release the two axes of movement, so that ultimately only two axes of movement are restricted by this kinematics, the seat surface storage kinematics 33.

[0069] The Figs. 8a and bThe figures depict such a seat without a base, i.e., from base 3, in frontal and side views. The kinematic mechanism 22, a known three-arm mechanism, supports the backrest 11 along with the rear of the seat, to which the (actual) seat surface 4 is pivotally attached about a horizontal transverse axis 34. Thus, in this example, the seat surface 4 can be rotated indirectly, via the backrest, (also) about the longitudinal axis 63. In this example, the longitudinal axis 63 is chosen to run steeply forward and downward, inclined relative to the horizontal, to illustrate the possibilities. This is achieved by combining the kinematic mechanism 22 with a seat surface storage mechanism 33.The longitudinal axis 63 (mathematically and theoretically infinitely long) runs above the seat 4 in the area of ​​the seating furniture 1 for most of its (technical) length. Only in its foremost part, in the area of ​​a compression plate 42, does it pass below this part of the seat due to the optimal 45° inclination chosen for this embodiment and the selected kinematics. In the torso area of ​​a user, thus near the backrest (or, if none is present, in the "rear" area of ​​the seat 4), the longitudinal axis 63 lies above the seat 4 or above the rear part of the seat 64 connected to a backrest.

[0070] It can therefore be concluded that the longitudinal axis 63, in the area of ​​the vertical projection P of the seat surface 4, in the example shown in combination with a rear seat surface section 64, thus of the entire seat surface, runs in the plane of symmetry for more than 75% of its defined length across the entire seat surface 4. The position of the "rear" end of the rear seat surface section 64, which is fixedly, usually in one piece, connected to the backrest 11, is not critical, as a glance at the Fig. 8b This shows that since the longitudinal axis lies almost entirely above the entire seat surface, even at the selected inclination of 45°, the requirement of 75% will always be met.

[0071] This applies to all kinematics used and to split or undivided seat surfaces. At slight inclines, this definitional problem does not arise at all due to the height of the central point 5, which, although below the user's center of gravity, is significantly above the seat surface. At inclines of 30° or less, the longitudinal axis 63 lies entirely above the seat surface 4 or 4 and 64 in area P. A backward, downward inclination of the longitudinal axis 63 is possible, but only makes sense in special cases and within narrower limits than a forward, downward inclination.

[0072] The (not shown) gas spring has its vertical axis with respect to base 3 in the Fig. 8b "front" mount, to which the unmarked lever for height adjustment leads, in Fig. 8cIt is the larger of the two cylindrical mounts; the central point 5 is therefore, in the usual view, "behind" this undrawn, vertical axis of rotation of the base and all components connected to it.

[0073] The rotation around the transverse axis at the central point 5 with the backrest facing backwards causes the (front) seat surface 4 to rotate clockwise around the (movable) transverse axis 34 in order to avoid constricting the back of the user's knees.

[0074] To control the relative movement between the backrest 11 and the seat surface 4, a seat surface storage kinematics 33 is provided according to the invention between the base 3 and a seat-surface-fixed control arm 43: A stationary support structure 36, consisting of three rods 37, is mounted on a base-fixed support plate 35, forming a support axis 38 at its free end. The three rods 37 are preferably rotatably mounted on the support plate 35 about axes parallel to the support axis 38 in order to avoid stresses in the rest state. Two lateral rods form a triangle, the third, central rod lies (preferably) in the plane of symmetry of the triangle, but not in its plane, so that a pyramid is formed. At the apex of the pyramid, two cranked arms 40 are rotatably mounted about the support axis 38, forming a triangle that lies approximately in a vertical plane in the rest position, the free side of which represents a bearing axis 39.

[0075] An approximately rectangular support plate 41 is rotatably mounted on the support plate 35, preferably about the axis around which the central rod 37 is mounted, and about the support axis 38. A compression plate 42 is rotatably mounted about the support axis 38 and the bearing axis 39. On one side, in the illustrated embodiment on the viewer's side (right side of the seat), the lower, free end of a seat-mounted control arm 43 is rotatably mounted on the bearing axis 39. Due to its flexible (actually also torsionally flexible and therefore buckling-resistant) design, this construction provides an elastic deformation of the two plates 41, 42 when the seat surface 4 pivots, which generates the restoring torque.

[0076] It is also possible, of course, to arrange a pin along axis 38 that also extends through the corresponding openings in plates 41 and 42, thus making the entire device stiffer and also including the rods 37 in the elastic deformation. By appropriate re-dimensioning compared to the variant described above, the same or similar restoring behavior can be achieved, depending on the desired outcome. This variant is particularly advantageous when a stronger counter-moment is required.

[0077] The construction with the rods 37 and the arms 40 ensures mechanical robustness in the event that a user sits only on the seat 4, thus reversing and significantly increasing the load conditions of both the kinematics 22 and the seat storage kinematics 33. Following slight elastic deformation of all components involved, the seat 4 rests centrally on the rigid supporting structure 36 in the area of ​​the support axis 38, and the load is transferred without damage.

[0078] When simply leaning backward without rotating about the longitudinal axis 63, the plates 41, 42 rotate about the three axes that hold them without any deformation and thus without generating a restoring moment. If, regardless of the angular position about the transverse axis at the central point 5, an (additional) pivoting movement with a component about the longitudinal axis 63 occurs, the plates 41, 42 are elastically deformed accordingly and a restoring moment is generated. This also applies to all other illustrated and described embodiments.

[0079] The Figures 9 to 12 Figures 63 show examples of strongly inclined longitudinal axes; the elongated, almost horizontal lever visible in these figures serves to adjust the height of the gas spring in the area of ​​the lower part 2 and has nothing to do with the invention.

[0080] The Figs. 9a-cFigure 1 shows an office chair, a seating element 1 with a base 2, a base 3, an undivided, upholstered seat 4, a backrest 11, and the kinematics 22 connecting the base 3 to the seat 4, in side and front views. In this embodiment, the central point 5 is not located on the vertical axis 9, but is positioned slightly offset towards the backrest 11. This results in a restoring moment when the seat and all components connected to it are tilted backward, since the user's center of gravity is located "in front" of the central point.

[0081] The inclination of 55° of the longitudinal axis 63 is achieved by a seat surface storage kinematics 33, which is the Fig. 8The arrangement is similar. A cylindrical stub is fixedly connected to the base 3 (and therefore designated with this reference numeral) and carries, pivotably about a horizontal first axis, a first spring plate 65, which is clamped at its other end by a joint body 66. This joint body is pivotable about a second axis, which in the installed state runs horizontally and parallel to the first axis, and carries a second spring plate 67, which is fixed at its other end in a receptacle 68. A holder 69, preferably made of sheet metal, is mounted on the seat surface, symmetrically to the plane of symmetry 62. The holder 69 is essentially U-shaped and is attached with its two legs projecting downwards. A bolt 70 is inserted through holes in the receptacle 68 and also projects through holes in the two legs of the holder 69. In this way, the receptacle 68 is rotatably connected to the holder about the bolt 70.

[0082] When the user tilts sideways, the two spring plates 65, 67 bulge, creating movement around the longitudinal axis 63. Depending on the bulge (which "forms" the energy storage), this axis is not exactly fixed in position; in practice, its position varies by a few millimeters in the lower area of ​​the seat storage kinematics 33, which goes completely unnoticed in practice.

[0083] The Figs. 10a-cFigure 1 shows an office chair, a seating element 1 with a lower section 2, base 3, a split, unpadded seat 4, a backrest 11, and the kinematic mechanism 22 connecting the base 3 to the seat 4, in side and front views. In this embodiment as well, the central point 5 is not located on the vertical axis 9, but is positioned slightly offset towards the backrest 11. This results in a restoring moment when the seat and all components connected to it are tilted backward, since the user's center of gravity is located "in front" of the central point.

[0084] The divided seat surface, namely the front part, the actual seat surface 4, and the rear part 64, which is (elastically) connected to the backrest 11 and to which the three-axis kinematics, the kinematics 22, are attached, are connected to each other via the transverse axis 34, which is horizontal in the rest position. This movable connection creates an additional degree of freedom, which is cushioned by the seat surface mechanism 31, which also serves as an energy storage device. This is achieved by the stiffening element 71, which otherwise completely corresponds to the seat surface mechanism of the exemplary embodiment. Fig. 9 The corresponding addition is also included. Everything else is the same as in the example embodiment of the Fig. 9 .

[0085] The Figs 11a and b show one of the Figs. 9a-cAnalogous situation with an undivided seat surface 4, wherein a simple seat surface storage kinematics 33 is used to achieve an even steeper slope of the longitudinal axis 63, namely 70°: It consists of a kinematics of the same structure as in Fig. 9c shown, their mounting on the base is also the same, but their point of attachment on the seat surface 4 is not via a U-shaped holder, but by means of the receptacle 68 directly on the underside of the seat surface.

[0086] The position of the longitudinal axis is in turn determined by the curvature of the spring plates, which (or their elastic deformation) also form the energy storage element 6 and is therefore variable in the millimeter range.

[0087] The Figs. 12a -c show the seating area of ​​the Fig. 10 with split seat surface 4, 64, with the seat surface storage kinematics 33 of the exemplary embodiment of the Fig. 11, to which a stiffening element 71, articulated on one side to the base 3 and on the other side to the joint body 66, is added, again to constrain the additional degree of freedom created by the transverse axis 34. In this embodiment as well, the position of the longitudinal axis 63 is determined by the elastic deformation of the seat surface storage kinematics 33.

[0088] Naturally, any seating furniture 1 that has an instantaneous center of gravity or at least an approximately horizontal (or even more strongly inclined) axis in the plane of symmetry (longitudinal axis) in the area of ​​the upper abdomen of a user (preferably, of course, below his center of gravity) can be equipped with one of the energy storage devices shown or with one of the other of the numerous designs available in the prior art.

[0089] The invention thus provides an efficient and easy-to-assemble device that provides a balancing moment without additional costs or space requirements.

[0090] The balancing moment can be generated by torsion as well as by the stretching and compression of components. The energy storage effect can be enhanced, and its effect varied, by one or more spring elements that can be switched on and off as needed.

[0091] It is also possible to adapt other areas of the kinematics and / or the seating furniture, such as the seat surface itself, as energy storage devices.

[0092] The invention is not limited to the three-arm kinematics shown (often also called two-arm kinematics because the object itself is usually not considered an "arm"; actually, three-axis kinematics would be more accurate). It can be universally applied to all technologies that have at least one approximately horizontal longitudinal axis in the plane of symmetry of the seating furniture in the region of the user's upper abdomen, about which the seat surface is pivotably mounted, or a central point that allows spherical movement of the seat surface. However, the three-axis kinematics shown are preferred over other kinematics known from the cited (and other) prior art because of their adaptability, robustness, and small footprint.

[0093] In the prior art literature attributable to the inventor, it is also pointed out that the three axes of the three-arm kinematics do not necessarily have to intersect at a single point (technically speaking, not mathematically), but rather pass close to one another, thus forming a central area in which every conceivable instantaneous center of rotation lies. Such a construction also forms a virtual longitudinal axis that is not fixed with respect to the base, but can change its position and orientation within limits depending on the relative position of the arms of the three-arm kinematics; one could also say that it is replaced by another, instantaneous, virtual longitudinal axis. Returning devices like the ones described can also be used with such kinematics; the users of the seating furniture will not notice any difference. This also applies to seating furniture such as the one based on the Fig. 4 described, if both kinematics used there form central areas.

[0094] For the application of the invention in the physical formation of the longitudinal axis 63, as is the case, for example, in EP 2 381 816 in the Figs. 7 -18 and the associated description, it can be said that an energy storage device, possibly a simple spring mechanism between the base and the seat, solves the problem.

[0095] In the design according to EP 1 090 568, in which the individual movement possibilities are created step by step (serially) by partial kinematics, such an energy storage device would be arranged on the side of the part of the partial kinematics facing the base, which enables movement around the longitudinal axis.

[0096] Knowing the invention, a person skilled in the art can easily provide different solutions. The arrangement and type of energy storage device, usually a spring mechanism such as a gas spring, a spring assembly, or similar, can also be easily selected.

[0097] Regarding the magnitude of the restoring torque, it can be said that it can be varied to a large extent depending on the user's wishes; it has proven effective for the restoring torque to be between 1.25 Nm / ° swivel angle and 20 Nm / ° swivel angle around the longitudinal axis 63, preferably 5 ± 10% Nm / ° swivel angle. Some brief explanations:

[0098] Pivot point:The pivot point, or at least one axis of rotation in the direction of the seat's movement, is positioned approximately at the level of the user's upper abdomen. This specific positioning is crucial for the chair's functionality, as it allows for natural freedom of movement while sitting, mimicking the movement of walking (this is state of the art).

[0099] Energy storage: An integrated energy storage system generates a counter-torque that supports both hip movement and the movement of the entire upper body when moving on the chair, without the user losing their stable balance. This counter-torque is designed so that it does not restrict movement, including hip movement, but rather promotes and supports it (a core aspect of the invention).

[0100] Objective:The aim of the invention is to avoid the health disadvantages of prolonged sitting. Sitting should be healthy in the future. The chair should encourage continuous movement, thereby stimulating metabolism and supporting the cardiovascular system, without making the user feel insecure or unstable.

[0101] Possible solutions, adjustments and effects: Investigation of the positioning of the pivot point and its influence on the balance.

[0102] Development of an approach to utilize a counter-moment through an energy storage device to ensure a stable equilibrium.

[0103] Adaptations to ensure freedom of movement and health benefits without compromising user safety and comfort. In summary, the following points are noted:

[0104] The invention relates to a piece of seating furniture 1 with a plane of symmetry 62 and with: a lower part 2 which has or has formed a base 3 in its upper area, and a seat surface 4 which is pivotably connected to the base 3 about a longitudinal axis 63 by means of a kinematic mechanism 22, wherein the longitudinal axis 63 lies in the plane of symmetry 62 in the rest position of the seat and is inclined relative to the horizontal from 5° backwards, downwards to 75° forwards, downwards, preferably by 45° ± 30°, most preferably between 40° and 50° forwards, downwards, wherein the longitudinal axis 63 is optionally formed virtually, and wherein the longitudinal axis 63 lies above the seat surface 4, optionally in combination with a rear seat surface part 64, for more than 75% of the length defined in this way.

[0105] The invention is characterized in that a restoring device 23 with an energy storage device 6 is provided between the base 3 and the seat surface 4, which exerts a restoring moment about the longitudinal axis 63 on the seat surface when the seat surface 4 is deflected about the longitudinal axis 63 from the rest position. To further explain the position of the longitudinal axis, the following is added:

[0106] If the longitudinal axis is inclined by up to 30° relative to the horizontal, the longitudinal axis 63 lies entirely above the seat surface 4 in the area of ​​the vertical projection (P).

[0107] If a backrest 11 is provided, the longitudinal axis 63 lies, regardless of its inclination, at least in the area up to 120mm in front of the backrest 11 above the seat surface 4.

[0108] An inclination of the longitudinal axis 63 backwards and downwards is possible, but only useful in special cases (medical applications, etc.) and within narrower limits (up to 5°) than forwards and downwards. The following additional information is provided to further explain the location of the central point:

[0109] No distinction is made here or in the following discussion between a central point and a central region. If the three arm axes do not (technically) intersect at a single point, then a central region exists instead of a central point. The effects are precisely described in the inventor's or applicant's documents discussed at the beginning and therefore require no further explanation here. It should merely be noted that the extent of a central region is barely perceptible in the low decimeter range and imperceptible in the centimeter range, and is therefore included in the term "central point."

[0110] The central point lies below the center of gravity of a user, including the seating furniture parts that move around the longitudinal axis 63, but above the seat surface 4.

[0111] It is preferably located at the level of the eleventh thoracic vertebra (thoracic vertebra) of a user.

[0112] If the seating furniture is an office chair, the central point is advantageously located slightly behind or even exactly on the vertical axis of rotation of the office chair, the vertical axis 9. The relationship between this axis of rotation, which is "supplied" by the lower part and around which the base 3 rotates, and the kinematics between the base 3 and the seat surface 4 has been explained in detail above. The following is added regarding energy storage:

[0113] The energy storage device 6 is "charged" with energy by the return device 23 (possibly in the form of a seat storage kinematics 33) when the seat surface 4 is deflected from the rest position about the longitudinal axis 63, thereby exerting a return torque on the seat surface 4 about the longitudinal axis 63 in the direction of the rest position. Reference symbol list:

[0114] 01 Seating furniture 37 staff, staffs 02 lower part 38 Support axis 03 base 39 Bearing axle 04 Seat area 40 poor 05 Central point 41 support plate 06 Energy storage 42 Squeeze plate 07 support arm 43 control arm 08 Floor 44 First axle 09 vertical axis 45 Second axle 10 Gas spring 46 Actuator axis 11 backrest 47 pivot arm axis 12 Arm point 48 Mounting plate 13 Seating point 49 Control knob 14 Cardan joint(s) 50 handling 15 Base arm 51 Tube 16 Interarm 52 Spring package 17 Endarm 53 Tube shoulder 18 line of action 54 Spring plunger 19 user 55 threaded rod 20 Arrow in longitudinal direction 56 Plates 21 Arrow in transverse direction 57 Rotary lever 22 Kinematics, overall 58 Rotary lever axis 23 Reset device 59 Longitudinal axis of rotation 24 Interleaved sheet 60 Connecting axle 25 actuator 61 intermediate axle 26 spring mechanism 62 plane of symmetry 27 Swivel arm 63 Longitudinal axis 28 connector 64 Rear seat section 29 Armrests 65 First spring plate 30 Assembly part 66 Joint bodies 31 Seat mechanism 67 Second spring plate 32 Mounting plate 68 Recording 33 Seat storage kinematics 69 holder 34 transverse axis 70 bolt 35 support plate 71 stiffening 36 supporting structure A0 Energy storage, resting length UH Energy storage length during rearward deflection AL Energy storage length when deflected to the left AR Energy storage length when deflected to the right H Horizontal plane P vertical projection of the entire seating surface in the plane of symmetry R Current minimum distance of the line of action 18 from the central point 5

Claims

1. Seating furniture (1) with a plane of symmetry (62) and with: - a lower part (2) which has or is formed a base (3) in its upper region, and - a seat surface (4) which is pivotably connected to the base (3) about a longitudinal axis (63) by means of a kinematic mechanism (22), - wherein the longitudinal axis (63) lies in the plane of symmetry (62) in the rest position of the seating furniture and is at an angle to the horizontal between 5° rearward and downward and 75° forward and downward, preferably by 45° ± 30°, particularly preferably by 45° ± 20° forward and downward, and most preferably between 40° and 50° forward and downward, - wherein the longitudinal axis (63) is optionally formed virtually, and - wherein the longitudinal axis (63) in the rest position lies in the region of the vertical projection (P) of the seat surface (4), optionally in combination with a rear seat surface part (64). more than 50% of the length (P) defined so above the seat surface (4),possibly in combination with the rear seat surface section (64), , characterized by the fact that A restoring device (23) with an energy storage device (6) is provided between the base (3) and the seat surface (4), which exerts a restoring moment on the seat surface (4) when the seat surface (4) is deflected about the longitudinal axis (63) from the rest position.

2. Seating furniture (1) according to claim 1, characterized by the fact that the kinematics (22) of the seat surface (4) enables a spherical movement around a central point (5) located above the seat surface (4) and virtually forms the longitudinal axis (63).

3. Seating furniture (1) according to claim 1, characterized by the fact that the kinematics (22) is a three-axis kinematics that defines a central point (5) or a central area and virtually forms the longitudinal axis (63).

4. Seating furniture (1) according to claim 2 or 3, characterized by - thatthe return device (23) is pivotally hinged to the base (3) at an arm point (12) and to the seat surface (4) at a seat point (13), - that the arm point (12) from the seat point (13) in the rest position of the seating furniture has a distance A0, - that the arm point (12), the seat point (13) and the central point (5) lie on a line of action (18), and - that the reset device (23) has an energy storage device (6) whose energy increases with an extension of the distance A0.

5. Seating furniture (1) according to claim 2 or 3, characterized by - that the energy storage device (6) of the reset device (23) is stored at the base (3) in a tube (51), - that the energy storage device has the form of a spring assembly (52) whose preload can be changed by means of a handle (5), wherein a threaded rod (55) protrudes through the spring assembly and is pivotably connected to a rotary lever (57) by means of a plate (56), - that the rotary lever (57) is pivotally attached to the base at one end about a rotary lever axis (58), - that The rotary lever (57) is rotatably mounted at its other end via two intermediate members, which are arranged in alignment and rotatably along their longitudinal extent, to the seat surface (4), preferably by means of a mounting plate (32), about a connecting axis (60).

6. Seating furniture (1) according to claim 2 or 3, wherein the kinematics (22) are connected via the backrest (11) and a rear seat surface part (64) fixedly formed with it to the seat surface (4), which is pivotable about a horizontal transverse axis and is connected to the rear seat surface part (64) by a support kinematics in its position relative to the rear seat surface part (64), - wherein the longitudinal axis (63) runs between the central point (5) and the front, upper region of the support kinematics, characterized by - thatThe restoring device uses the elastic deformation of the load-bearing kinematics as an energy storage device and is thus a seat surface storage kinematics (33) whose targeted deformation is achieved by: - that a control arm (43) provided on one side of the seat surface (4) and fixedly connected to it, is pivotably connected at its other end about a horizontal bearing axis (39) running normal to the plane of symmetry (62) and provided at the lower edge of a substantially vertically arranged crushing plate (42), - that the crushing plate (42) is pivotably connected at its upper edge about a support axis (38) running parallel to the bearing axis (39) to the front edge of a support plate (41), the rear edge of which is hinged at the base about an axis running parallel to it; - that a pyramid consisting of three rods (37) with a fixed base and an apex through which the support axis (38) runs is provided, - thatTwo arms (40) extend laterally outwards from the tip and pivotably extend, their free ends being pivotably mounted on the bearing axis (39), - whereby, when deflected from the rest position, the control arm (43), the crushing plate (42) and the support plate (41) are elastically deformed and thus act as energy storage devices and provide the restoring torque.

7. Seating furniture (1) according to any of the preceding claims, characterized by the fact that the restoring torque is between 1.25 Nm / ° swivel angle and 20 Nm / ° swivel angle around the swivel axis (63), preferably 5 ± 10% Nm / ° swivel angle.

8. Seating furniture according to one of the preceding claims, characterized by the fact that the longitudinal axis (63) is inclined to the horizontal by no more than 30°, preferably by no more than 15°.

9. Seating furniture according to one of the preceding claims, characterized by the fact thatthe longitudinal axis (63) is located in the rear third of the seat surface (4), optionally in combination with a rear seat surface part (64), at the level of the ninth to twelfth, preferably at the level of the eleventh thoracic vertebra of a user.

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