Patent Application
20200383480
The present invention relates to a chair with a self-adjusting elastic joint.
There are various seating systems, which can be divided into three sections: a base section (base or support), an intermediate section (e.g. multiple legs), and an upper section (seat or seat part).
Most chairs, stools, or seats traditionally have a rigid connection for the two interfaces between the base, the intermediate section, and the seat. More recent developments have provided a flexible connection for at least one of these interfaces with an associated restoring mechanism.
Such movable or active dynamic chairs differ with respect to static chairs in that a chair user sitting on the chair can perform torso and body movements together with the seat part, which is not possible with static chairs.
Human physiology prefers dynamic movements to static rest when sitting as well. Chairs which at the same time carry the weight of the legs should not just allow dynamic movement but also provide ergonomic support to the seat user.
Seating furniture is in most cases equipped with seating surfaces and backrests designed accordingly in an anatomically maximally favorable position, such that the body, particularly the back, is supported. Such seating furniture is often felt to be comfortable but has the decisive disadvantage that the body just sits passively, that is, the back muscles are rarely placed under stress and the intervertebral disks are subjected to a permanent compressive load. After extended use of these seating devices, this can lead to degeneration of the back muscles and wear on the intervertebral disks. Health problems and pain in the back and hip regions are a frequent consequence of static or passive sitting.
This is why active dynamic seating devices were developed which allow so called active dynamic sitting in which the back muscles and the intervertebral disks are always slightly active. This active dynamic sitting position is achieved in virtually all cases in that the actual seat of the seating device is held in an unstable position and can be moved by a seat user back and forth between a resting position and a laterally deflected position.
Such an active dynamic pendulum chair is known, for example, from DE 42 44 657 02. This document describes a generic type of seating device which consists of a base part, an intermediate piece connected to the base part, and a seat part that is rigidly connected to the intermediate piece, wherein the intermediate piece is kept tiltable into every lateral direction using an elastically deformable connecting member in an opening of the base part and restored to its neutral position (resting position) in an unloaded state.
For example, U.S. Pat. No. 5,921,926 shows an active dynamic pendulum chair, which is also based on the principle of an inverted pendulum. Such chairs have a defined path of movement and a structural restoring mechanism, which at the same time comprise a protective device to prevent the chair from toppling over. However, the seat tilts into a position inclined away from the body center when the pendulum is moved backwards from a horizontal position.
Such pendulum chairs allow swinging the seat back and forth from the undeflected starting position into various deflected positions, whereby the seating surface tilts from its horizontal position into an inclined position. The tilting angle depends on the deflection direction and the degree of deflection. For example, in a pendulum chair in which the horizontally mounted seat is firmly connected to a pendulum column that can be moved back and forth, the seat moves into a clearly inclined position the more the column is deflected from its horizontal position.
EP 0 808 116 B1 describes a pendulum bearing which is disposed between the column and the base part. The pendulum bearing is designed as a rubber-bonded metal and consists of one substantially tubular top part, the top end of which is used for a splined connection, and a bottom part, which is firmly attached to an arm of the base part and an elastic material disposed between the top and bottom parts. The pendulum bearing allows the seat part to swing back and forth. A sitting person can move into every lateral direction by swinging about a point (inclining). The axial load (bearing load) that is applied to such a system depends on the weight of the sitting person and influences lateral movement deflection (tilting load). This concept therefore provides a setting for the stiffness of the flexible connection. While this solution of spring stiffness adjustability can be sufficient in a single user environment, a better solution must be found for a multi-user environment.
Ideally, the stiffness of the flexible joints (particularly for the tilting load) would be a dynamic and self-adjusting function of the user's seated weight.
DE 10 2009 019 880 A1 therefore discloses an item of seating furniture having a seat and a pendulum device for performing pendular movements of the seat with a device for automatic adjustment of the pendulum return force depending on the weight of a person using the seat. This item of seating furniture comprises a seat, a spring strut, a base, and a pendulum device as well as a device for automatic adjustment of the pendulum return force. This item of seating furniture is configured such that the lever arm in a bottom bearing of the center column is extended if the spring strut carrying the seat sinks in deeper due to a higher body weight of a user, whereby the resistance to lateral deflection increases as the seat user's body weight increases.
As can also be derived from DE 10 2009 019 880 A1, the device has a complex structure. A bearing housing, a plurality of rubber bearings disposed in the holder, a control element that can be moved along the rubber bearings, and an upper radially circumferential rubber seal are used to close the device towards the outside. Furthermore, the device comprises a coil spring on which the control element rests. The penetration depth of the control element into the bearing housing results from the body weight of the seat user and the spring constant of the coil spring.
It is a disadvantage of this restoring device that it uses a coil-type (compression) spring as means for regulating the penetration depth and that his means predominantly produces a restoring force in the axial direction. Various bending moments result as a function of the penetration depth, and the coil spring which is to be operated axially is twisted accordingly. Furthermore, the restoring device has a complex structure, and its properties are determined by the interaction of the various components that can be moved relative to each other. Mechanical abrasion may also occur due to the relative movement between the control element and the rubber bearings.
Starting from this device, it is the problem of the present invention to provide an alternative restoring device for automatic adjustment of the return force, which device is less complex in structure and overcomes the disadvantages mentioned and allows complex motion dynamics of the seat part.
This is because it is desirable for dynamic movements of a sitting person, that said person can move his or her entire body including his or her torso similar to moving with a hula hoop, and in this process to perform both pendular movements “as such” and “lateral” deflections (i.e. horizontal translational movements) with his or her pelvis to compensate for weight shifts of the upper regions such as the arms and the head, and to set these regions into motion. It is also desirable in this context that the front seat part does not go down as usual during a forward movement in the forward direction, and that the rear seat part is not go down as usual during a rearward movement in the rearward direction, but that instead performs a motion curve similar to the movement of a seat of a swing.
Based on prior art, the problem underlying the present invention therefore is to overcome the disadvantages mentioned and to provide an active dynamic chair in which a seat user can perform safe and manifold movements of the seat part in a defined moving space. Advantageously, the chair is to allow a chair user to perform horizontal translational movements of the seat area, and the change in seat inclination is to take place in accordance with the chair user's ergonomic needs.
The invention is thus based on the concept of a self-adjusting joint, including an inner cylinder having an upper and a lower end-face edge and an outer cylinder arranged around the exterior of the inner cylinder (having a greater diameter), likewise having an upper and lower end-face edge, wherein said edges are offset relative to the upper and lower end-face edge of the inner cylinder in the axial direction, as well as an first (elastically deformable) compression spring section that consists of a plurality of cylinder bodies which surround the inner cylinder and between which a respective elastomer section is arranged so as to connect the cylinder bodies and a second compression spring section that is arranged at a distance from the first compression spring section in the axial direction and consists of a plurality of cylinder bodies which surround the inner cylinder and between which a respective elastomer section is arranged so as to connect the cylinder bodies.
Furthermore, multiple secondary problems and advantages of the present invention include providing a motion joint and particularly a chair having such a joint, which chair:
(a) provides sufficient axial (vertical) deflection to allow “attenuation”
(b) allows a tilting movement;
(c) provides increased tilt stiffness as a function of an increased axial load;
(d) allows limited torsion;
(e) provides a restoring mechanism for tilt, torsion, and axial load;
(f) allows uniform movement;
(g) is user-friendly and safe.
These problems are solved by the measures described in the coordinate independent claims. Advantageous embodiments of the invention are described in the respective dependent claims.
In a special embodiment of the invention, the first elastomer sections between the first cylinder bodies are formed separately from the second elastomer sections of the second cylinder bodies and that a hollow space is formed between the respective elastomer sections (when viewed in the axial direction).
Advantageously, the multiple cylinder bodies are arranged to each other like onion skins, and said elastomer bodies are located between the respective cylinders.
It is further advantageous that an end-face edge of the respective cylinder bodies located farther outwards is arranged at an offset in the axial direction relative to the end-face edge on the same side of the cylinder bodies located farther inwards.
It is further advantageous that the cylinder bodies of the first compression spring section are formed separately from the cylinder bodies of the second compression spring section.
Also advantageous is a design in which the cylinder body of the first compression spring section is connected to the cylinder body of the second compression spring section or the cylinder bodies are formed integrally in one piece as joint cylinder bodies.
In another advantageous embodiment, a hollow space is formed between the upper and lower elastomer sections, which is filled with a gaseous medium, air, or an elastomer having a significantly lower Shore hardness than the elastomer in the elastomer section.
Another aspect of the present invention relates to an active dynamic chair having a base, at least one chair leg, and a seat mounted to the top end of the chair leg, wherein at least the bottom end of the chair leg is fastened in a self-adjusting joint as described, which joint is located on the base.
Other problems and advantages are illustrated by the description below and the drawings.
The invention is described in more detail below with reference to
The inner tubular cylinder body 12 (hollow cylinder with a round cross sectional area) provides a receiving space for a chair leg and has a substantially cylindrical inner wall with an inner diameter which remains constant between the top compression spring section 11a and the bottom compression spring section 11b.
As is clearly apparent from the figures, the inner cylinder 12 has a wall of different wall thicknesses, wherein the wall thickness initially decreases in the embodiments according to
A hollow space 25 is located between the top compression spring section 11a and the bottom compression spring section 11b, which space is either filled with a medium such as air or with an elastomer 27 as shown in
The self-adjusting joint 11 further comprises an outer cylinder 13 (formed of a rigid material). The rigid inner cylinder 11 and the rigid outer cylinder 13 are interconnected, respectively, by two parts, i.e. spatially separated top and bottom elastomer sections 14a and 14b.
The elastomer sections 14a and 14b are each further divided by rigid hollow tubular cylinder bodies 15a and 15b, which are arranged like onion skins relative to each other. Therefore the cylinder bodies 15a, 15b located farther inwards have a smaller diameter than the cylinder bodies 15a, 15b located farther outwards. In a preferred embodiment of the invention, the radial distances of the respective hollow cylinder bodies 15a or hollow cylinder bodies 15b are about the same, such that an approximately equidistant arrangement of cylinder bodies results when viewed in the radial direction. One elastomer is annularly inserted between each of the adjacent cylinder bodies 15a and 15b. When viewed in the radial direction with respect to the central axis through the inner cylinder 11, the upper and lower edges R of the cylinder bodies 15a or 15b located farther outwards are arranged at an offset in the vertical direction with respect to the cylinder bodies 15a or 15b located farther inwards in the representation, such that the joint 11 has an outwardly conically downward sloping lid structure, which in the normal state (i.e. without a force being applied via a chair leg 21) defines a tangential plane through the upper edges of the cylinder bodies 15a or 15b, respectively, which plane is tilted by the tangential angle 20 with respect to a horizontal plane.
The conical compression spring sections 11a and 11b have a height 17a and 17b, respectively, (which can be same or different depending on the desired spring characteristic), a width 19, and a diameter 22.
As is further well apparent in the figures, the inner cylinder 12 has a wall with increasing wall thickness in the axial direction in the region between the top and bottom compression spring sections 11a, 11b, namely where these are connected to the inner cylinder 12.
The wall thickness then decreases again in the region of the bottom compression spring section 11b.
Since the support member 21 is mounted in two bearing areas (an area between the top scoring section 11a on the one hand and an area between the bottom spring section 11b on the other), the support member 21 can be tilted.
If an additional axial load 22 is applied to the support member 21, the compression spring sections 11a and 11b are partially lowered and thereby laterally compressed and vertically sheared in relation to each other, whereby the tilt stiffness of the support member 21 is automatically increased without the seat user having to adjust the characteristic manually to his or her weight.
All dimensional and material parameters determined may be used to adjust the characteristic of the self-adjusting motion joint 11. For example, an elastomer with a higher hardness may be used to achieve a higher overall stiffness of the joint.
The number of the rigid cylinder bodies 15a, 15b may also be increased to increase tilt stiffness without impairing axial attenuation. An increased height of each spring section increases both inclination and axial stiffness. An increased width of each spring section reduces axial stiffness. An increased distance between the spring sections increases tilt stiffness but does not impair axial stiffness.
This last point indicates the reason for a two-part design of the self-adjusting motion joint: While the height of a spring section increases both inclination and axial stiffness, the distance between the spring sections only increases the inclination of the slope but not the axial stiffness.
In
As is apparent from
A cylindrical adapter element would be conceivable which is mounted as a spacer to the bottom side of the joint 11.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2019/050450 | 1/9/2019 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62615476 | Jan 2018 | US |
