Central unit for chair

Abstract

The invention relates to a central unit (10, 10a, 10b, 10c, 10d) for a chair, in particular an office chair, characterized in that a multi-joint body (12, 12a, 12b, 12c, 12d, 12e, 12f) is provided, which has a seat part (14) for a seat (16), a backrest part (18) for a backrest (20), a support part (22) for a support column of a foot rest, and a front part (24, 24a) arranged between the seat part (14) and the support part (22), according to the invention, the multi-joint body (12, 12a, 12b, 12c, 12d, 12e, 12f) has at least three joints (26, 28, 30, 32), each of which connects two of the parts in an articulated manner.

Description

Technical Field

[0001] The present invention relates to a central unit for a chair, in particular an office chair. Background Art

[0002] Office chairs usually have a mechanical component as the central part, which is mainly made of metal. The mechanical component allows the footrest to be fixed thereon. In addition, the seat and the backrest are arranged on the central part. The central part usually ensures that the backrest and the seat can move synchronously with each other.

[0003] In the field of office chairs, manufacturers are also facing increasingly high requirements regarding sustainability and recyclability. Traditional office chairs have multiple components, which must be separated at great expense for recycling, and some of them are not recyclable at all. Summary of the Invention

[0004] Therefore, the object of the present invention is to provide a central unit for a chair, which is simply constructed and recyclable.

[0005] This object is solved according to the present invention by a central unit for a chair, in particular an office chair, which has a multi-joint body having a seat part for the seat, a backrest part for the backrest, a support part for the struts of the footrest, and a front part arranged between the seat part and the support part, wherein the multi-joint body has at least three joints, and each of the at least three joints articulately connects two of the parts. The central unit can preferably be manufactured from only one material, for example, by an injection molding method. If the central unit is manufactured from only one material, the central unit can be easily recycled. At least three joints can be constructed in the same type, so that different joints do not have to be stocked for the assembly of the central unit.

[0006] Particularly advantageously, at least one of the joints, in particular at least three joints, preferably four joints, are constructed as solid joints. The following region of a component is called a solid joint, which allows relative movement (rotation) between two rigid body regions through bending. The solid joint is based on the elastic principle. The function of the joint is achieved by the region which has a smaller bending stiffness compared with two adjacent regions. The reduced bending stiffness can be produced by locally reducing the material strength. The solid joint is usually also called a film joint, a film hinge or a flat joint. The solid joint is hinged and does not have mechanical parts. Thus, mechanical parts that do not need to be recycled later can be saved by the solid joint.

[0007] In principle, it is also conceivable that the solid joints are designed as separate components and are respectively connected to two of the parts, namely the seat part, the backrest part, the support part, and the front part. However, it is particularly advantageous that the solid joints are integrally formed, in particular materially joined, with the parts to which they are connected. Here, the solid joints and the parts connected thereto can be manufactured, for example, by an injection molding process. Thereby, subsequent assembly work can be eliminated.

[0008] Preferably, at least the seat part, the backrest part, and the support part are rigidly constructed, and the solid joints are flexibly, in particular elastically, constructed. The seat part, the backrest part, the support part, and / or the front part are constructed more rigidly than the solid joints. Preferably, the solid joints have a smaller material thickness compared to the seat part, the support part, the front part, and / or the backrest part.

[0009] It is particularly advantageous that the multi-joint body is integrally formed. Thereby, the multi-joint body can be manufactured in one piece, for example, by an injection molding method. The seat part and / or the backrest part can be constructed such that the seat, for example, the seat shell, and the backrest can be fixed to the seat part or the backrest part. However, it is also conceivable that the seat part and the backrest part are constructed such that the seat part and the backrest part are already the seat and the backrest. If necessary, a seat cushion or a backrest cushion can also be arranged on the seat and the backrest. In this way and method, an (office) chair with very few individual components is achieved, and these components can be easily disassembled and recycled from each other after the normal use of the chair.

[0010] If the multi-joint body is made of plastic, in particular glass fiber-reinforced plastic, preferably glass fiber-reinforced polyamide, then the multi-joint body can be manufactured by an injection molding method in a particularly simple way and method. The multi-joint body can also be recycled simply.

[0011] According to one configuration of the present invention, it can be provided that exactly one of the joints is designed as a hinge with a rotary pin. Here, a multi-joint body with a receiving portion for the rotary pin can be molded. The receiving portions can then be connected to each other by the rotary pin to form a joint. The remaining joints of the central unit can be designed as solid joints.

[0012] According to another configuration of the present invention, it can be provided that the front part is elastically bent. The other parts, in particular the seat part, the backrest part, and the support part, can be rigidly or at least more rigidly constructed here. The front part can have a joint, in particular a solid joint, only at one end. Thereby, the number of joints can be reduced. The multi-joint body can particularly have only three joints. The three joints can be designed as solid joints here. In this embodiment, the front part can particularly have a smaller material strength compared to the support part, the backrest part, and the seat part, but a larger material strength compared to the solid joints.

[0013] In order to provide sufficient resistance for the backward tilting of the backrest, it can be advantageous to arrange a spring assembly between the seat part and the support part. The spring assembly can have, for example, one or more spring elements here, and the spring elements can be configured in the form of leaf springs. The spring assembly can be manufactured together with the remaining multi-joint body by an injection molding method. At least one spring element of the spring assembly can be integrally formed with the seat part and the support part here, in particular in a material-fitting manner.

[0014] In order to be adjustable for different user weights in the central unit, the spring assembly can have at least one spring element that can be activated and deactivated or is arranged on the multi-joint body. The spring element can, for example, be integrally formed with the seat part at one end. The other end of the spring element can be pivotally arranged on the support part. The swingability can be locked by a slider. In the locked position, the spring element exerts its spring action, while the spring element is deactivated in the position released by the slider. Alternatively, a plurality of spring elements can be provided. The spring elements can be the same, and depending on the required spring force, one or more spring elements can be arranged on the multi-joint body. In addition, spring elements with different widths, different thicknesses, and / or made of different materials can be provided. The spring elements required for the required spring force can be mounted on the multi-joint body.

[0015] According to one configuration of the present invention, a limiting assembly can be provided for limiting the maximum relative movement between the seat part and the backrest part. In particular, two stops can be provided, one of which defines the maximum opening angle between the seat part and the backrest part, and one stop defines the minimum angle between the seat part and the backrest part.

[0016] In addition, a manually operable locking mechanism can be provided for locking the relative position of the seat part and the backrest part. By means of the above measures, the opening angle between the backrest part and the seat part can be determined.

[0017] In addition, a manually operable seat tilt limiter can be provided. The locking mechanism and the seat tilt limiter can be combined here.

[0018] A pin can be arranged on the backrest part, and the pin is guided in a sliding groove of a guiding part arranged on the support part. The two end points of the sliding groove are stops here, which limit the relative movement between the seat part and the backrest part. In order to ensure particularly good stability, the pin and the guiding part can be made of metal.

[0019] The locking device can be pivotally arranged on the guide part. The locking device has a stop for the pin and a locking receptacle for the pin. If the locking device is in the position where the pin can abut against the stop, the seat inclination can be restricted by the stop. If the locking device is in the position where the pin is received by the locking receptacle, the relative movement between the seat part and the backrest part is prevented.

[0020] It is also advantageous that a component having a receptacle for the strut of the footrest is arranged on the support part. Especially if the component is made of metal, sufficient stability for receiving the strut of the footrest is achieved. The locking mechanism and the seat inclination limiter can also be implemented on the component so as to also achieve functions with sufficient stability. In the case of recycling, the component can be easily disassembled from the multi-joint body so that the two parts can be recycled separately.

[0021] The guiding device for receiving the seat and / or the backrest can be arranged on the seat part and / or the backrest part. This facilitates the assembly of the seat and / or the backrest. The guiding device can be constructed in a dovetail shape.

[0022] The plug-in connection element for assembling the seat element and / or the backrest element can be arranged on the seat part and / or the backrest part. This enables an easy possibility for assembling the seat and the backrest. The seat part and the backrest part can be components or central elements of the seat or the backrest.

[0023] The armrest can be arranged in a material - fitting manner on the backrest part. In particular, the armrest can be injection - molded on the backrest part or be an integral part integrated with the backrest part.

[0024] Within the framework of the present invention, there is also a chair, especially an office chair, which has a central unit according to the present invention. Description of the Drawings

[0025] Other advantages of the present invention result from the description and the drawings. The aforementioned and further implemented features can equally be used separately or in any arbitrary combination according to the present invention. The shown and described embodiments should not be understood as an exhaustive listing, but rather have exemplary features for describing the present invention.

[0026] In the drawings:

[0027] Figure 1 A multi - joint body with four membrane hinges is shown in a side view;

[0028] Figure 2 A perspective view of a multi - joint body with four joint sites in the basic position is shown;

[0029] Figure 3 Shown corresponding to Figure 2 A view with a backward - swinging backrest is shown;

[0030] Figure 4 Shows an embodiment of a multi-joint body, wherein the seat portion and the support portion are connected by a spring assembly;

[0031] Figure 5 Shows corresponding to Figure 4 a view of the backrest with backward swing;

[0032] Figure 6 Shows a cross-sectional view of a multi-joint body cut through a spring assembly with a plurality of spring elements.

[0033] Figure 7 Shows corresponding to Figure 6 a view of the spring elements being activated;

[0034] Figure 8 Shows the configuration of a multi-joint body with a front portion having flexural elasticity;

[0035] Figure 9 Shows corresponding to Figure 8 a view in which the backrest swings backward.

[0036] Figure 10 Shows a multi-joint body in which only three joints are configured as solid joints;

[0037] Figure 11 Shows Figure 10 a multi-joint body of in which the joints have rotating pins;

[0038] Figure 12 Shows a central unit with a multi-joint body and a locking mechanism;

[0039] Figure 13 Shows a central unit with a limiting assembly;

[0040] Figure 14 Shows a central unit with a locking mechanism;

[0041] Figure 15 Shows the locked locking mechanism;

[0042] Figure 16a Shows a multi-joint body having receiving portions for the seat and the backrest;

[0043] Figure 16b Shows Figure 16a a multi-joint body during the assembly of the seat and the backrest of ;

[0044] Figure 16c Shows a backrest suitable for assembly;

[0045] Figure 17Shows a further multi-joint body having plug-in connection elements for assembling a seat element and a backrest element;

[0046] Figure 18 Shows a multi-joint body having an armrest arranged in a form-fitting manner on the backrest part.

[0047] Figure 19 Shows a side view of a multi-joint body having a mounting for one or more spring elements;

[0048] Figure 20 Shows Figure 19 A side view of the multi-joint body with the spring element inserted;

[0049] Figure 21 Shows a side view of the spring element;

[0050] Figure 22 Shows a perspective view of the spring element. Detailed description

[0051] Figure 1 Shows the central unit 10 of a chair, in particular an office chair, which has a multi-joint body 12. The multi-joint body 12 has a seat part 14 for the seat 16, a backrest part 18 for the backrest 20, a support part 22 for the footrest and a front part 24. The seat part 14 is connected to the backrest part 18 by a joint 26, which is configured as a solid joint. The backrest part 18 is connected to the support part 22 by a joint 28, which is configured as a solid joint. The support part 22 is connected to the front part 24 by a joint 30, which is configured as a solid joint. The front part 24 is connected to the seat part 14 by a joint 32, which is configured as a solid joint. The joints 26, 28, 30, 32 have a lower material strength compared to the seat part 14, the backrest part 18, the support part 22 and the front part 24. The seat part 14, the backrest part 18, the support part 22 and the front part 24 are rigidly constructed. The joints 26, 28, 30, 32 are constructed less rigidly, i.e. flexibly, in particular elastically. The material strength of the joints 26, 28, 30, 32 can be the same or different. Two joints can also each have the same material strength.

[0052] In the illustrated embodiment, the multi-joint body 12 is configured as a four-joint. The seat part 14, the backrest part 18, the support part 22 and the front part 24, as well as the joints 26, 28, 30, 32 arranged therebetween, surround the opening 34. The multi-joint body 12 can be integrally constructed. The joints 26, 28, 30, 32 can in particular be integrally constructed with the parts connected thereto, in particular in a material-fitting manner. The seat 16 and the backrest 20 can be separate parts and connected to the multi-joint body 12. However, it is also conceivable that the seat 16 and the backrest 20 are also integrally constructed with the multi-joint body 12, in particular in a material-fitting manner. The multi-joint body 12 can in particular be made of plastic together with the seat 16 and the backrest 20 if necessary and manufactured by an injection molding method.

[0053] Figure 2 Shows Figure 1 A perspective view of the central unit 10 in the basic position. This means that no force is applied to the backrest 20 or the seat 16 and thus the multi-joint body 12 is not deformed.

[0054] In Figure 3 's view, a force is applied to the backrest 20 so that the force swings backward. Thereby, another shape of the opening 34 is obtained. This is achieved by the joints 26, 28, 30, 32 being made of an elastic material, so that when no external force is applied to the backrest 20 anymore, it automatically returns to Figure 2 's position. In Figure 3 , the backrest 20 and the seat 16 have a greater angle with each other than in Figure 2 .

[0055] In the embodiment of the central unit 10a according to Figure 4 , a spring assembly 36 is provided between the seat part 14 and the support part 22. The spring assembly 36 can be integrally constructed with the seat part 14 and the support part 22, in particular in a material-fitting manner. By means of the spring assembly 36, the resistance for swinging the backrest 20 back can be increased. The spring assembly 36 can be said to divide the opening 34 into two halves.

[0056] Figure 4 Shows the central unit 10a in the basic position, i.e., in the case where the backrest 20 does not swing relative to the seat 16.

[0057] Figure 5 Shows the central unit 10a after the backrest 20 has swung backward relative to the seat 16. It can be seen that not only the spring assembly 36 but also the opening 34 has been deformed. The spring assembly 36 can have only one spring element, which is constructed in the form of a leaf spring. However, the spring assembly 36 can also be constructed according to Figure 6 .

[0058] Figure 6The spring assembly 36 has a plurality of spring elements 38, 40. The spring element 38 is fixedly connected to the seat part 14 and the support part 22, in particular integrally formed with the seat part and the support part. The spring element 40 is only connected to the seat part 14 in the illustrated embodiment, in particular integrally formed with the seat part. The end 42 of the spring element 40 on the support part side is rotatably mounted on the support part 22 via a rotary shaft 44. When the seat part 14 thus moves relative to the support part 22, the end 42 can swing relative to the support part 22, so that the spring element 40 does not function. A slider 46 is provided to activate the spring element 40, and the slider can move relative to the support part 22. The slider 46 can be pushed into the groove 48 to activate the spring element 40, as shown in Figure 7 as shown. In this case, the end 42 can no longer swing around the shaft 44, so that the spring element 40 exerts its function and resists the relative movement between the seat part 14 and the support part 22 when a force is applied to the backrest 20. A spring element similar to the spring element 38 can also be provided. The spring element 40 can in particular be arranged between the two spring elements 38.

[0059] Figure 8 Shows another variant of the central unit 10b. This embodiment only has joints 26, 28, 32. The front part 24a is elastically bent. The front part has a material strength that is less than the material strength of the seat part 14, the backrest part 18 and the support part 22, but greater than the material strength of the joints 26, 28, 32. Through this configuration, the stiffness of the multi-joint body 12b can be further increased. Compared with the configuration of Figure 1 , in particular, the force for deforming the multi-joint body 12 can be increased in this way.

[0060] Figure 8 Shows the multi-joint body 12b in the basic position, that is, when the backrest 20 does not swing relative to the seat 16. Figure 9 Shows the situation after the backrest 20 swings relative to the seat 16. It can be seen here that the front part 24a is also deformed thereby. In the configurations according to Figure 8 and 9 , the front part 24a is integrally formed with the support part 22. It can also be considered to cancel the joint 32 and directly connect the front part 24a to the seat part 14 and retain the joint 30 between the front part 24a and the support part 22 for this purpose.

[0061] Figure 10Shows another embodiment of the central unit 10c. The multi-joint body further has a seat portion 14, a backrest portion 18, a support portion 22, and a front portion 24. The seat portion 14 and the backrest portion 18 are connected by a joint 26 configured as a solid joint. The support portion 22 and the front portion 24 are connected by a joint 30 configured as a solid joint. The front portion 24 and the seat portion 14 are connected by a joint 32 configured as a solid joint. However, the joint 28 is not configured as a solid joint in this case. A pin receiving portion 50 is constructed on the backrest portion 18, and a pin receiving portion 52 is constructed on the support portion 22. The pin receiving portions 50, 52 can be connected by a pin so as to form the joint 28 thereby. In this case, the multi-joint body 12c thus has only three solid joints. The special feature of this embodiment is that, Figure 10 the multi-joint body 12c shown in

[0062] Figure 11 Shows the multi-joint body 12c with the joint 28 fully installed, i.e., after the pin 54 has been inserted into the pin receiving portions 50, 52. In principle, it is also conceivable that the other joints 26, 30, 32 are configured as joints with pins. However, preferably, at least three of the joints 24, 28, 30, 32 are configured as solid joints.

[0063] Figure 12 Shows the central unit 10d with the multi-joint body 12. Components 60, especially metal components, are arranged on the multi-joint body 12. The components include, on the one hand, a receiving portion 62 for receiving a strut of a footrest (not shown here). In addition, as can be seen from the following views, a limiting component, a locking mechanism, and a seat tilt limiter are constructed on the component 60.

[0064] It can be seen from omitting half of the central unit 10d that Figure 13 a guiding portion 64 is provided, which has a sliding groove 66. A pin 68 is arranged in the sliding groove 66, and the pin is fixed on the backrest portion 18. The sliding groove 66 limits the movement clearance space of the pin 68. Thereby, the relative movement between the seat portion 14 and the backrest portion 18 is restricted. The two ends of the sliding groove 66 are end stops for the pin 68.

[0065] Furthermore, a lock 70 can be seen, which is pivotally arranged on the guiding portion 64. The lock 70 is coupled to an operating handle 74 by a toggle mechanism 72. By operating the operating handle 74, the lock 70 can be pivoted.

[0066] In the case of the lock 70 Figure 14In the pivoted position shown, the stop 76 locks the further movement of the pin 68 in the chute 66. Thereby, the mobility of the seat part 14 is restricted, thus achieving a manually operable seat tilt restriction. However, the further relative movement between the seat part 14 and the backrest part 18 remains possible in the sense of an increasing angle between the seat part 14 and the backrest part 18 until the pin 68 abuts against the right end of the chute 66.

[0067] Figure 15 Shows a further pivoted position of the lock 70, in which the pin 68 is received in the locking receptacle 78 of the lock 70. Thereby, the locking mechanism is achieved. The relative position of the seat part 14 and the backrest part 18 is locked. The assembly 60 can be a metal assembly. However, the assembly can also be made of other materials, such as plastic. In any case, the assembly 60 can be completely disassembled from the multi-jointed body, thus achieving recyclability.

[0068] Figure 16a Shows the multi-jointed body 12d, in which the seat part 14 has a guiding device 90 onto which the seat can be pushed. The guiding device 90 is constructed in a dovetail shape in cross-section in the shown embodiment. Thereby, it is ensured that the pushed-on seat cannot be easily removed upwards. Thereby, the seat remains in its position. The guiding device 90 has a locking groove 92 so that the seat can be locked with a corresponding locking projection on the guiding device 90.

[0069] A guiding device 94 for receiving the backrest is provided on the backrest part 18. The guiding device 94 is also constructed in a dovetail shape in cross-section. The guiding devices 90, 94 can be constructed in a material-fitting manner with the seat part 14 or the backrest part 18. In particular, the guiding devices 90, 94 can be injection-molded onto the seat part 14 or the backrest part 18, especially simultaneously with the multi-jointed body 12d.

[0070] Empty slots 95, 97 are provided on the backrest part 18, and the empty slots can be constructed as through holes. By a suitable selection of the number, shape, and size of the empty slots 95, 97, the bending stiffness of the backrest part 18 can be set.

[0071] Figure 16b Shows that the backrest 20 can be pushed onto the guiding device 94 along the arrow direction 98. The seat 16 can be pushed onto the guiding device 90 along the arrow direction 100. Thereby, it is achieved that the seat 16 and the backrest 20 can be fixed particularly easily on the multi-jointed body 12d.

[0072] Figure 16cIt is shown that the backrest 20 has, on its back side, a guide device 96 corresponding to the guide device 94, with which the backrest 20 can be pushed onto the guide device 94. The guide device 96 is configured substantially U-shaped, such that the upper horizontal bar forms a stop, which prevents the backrest 20 from being pushed too far onto the guide device 94. The seat 16 can have a corresponding guide device on its underside.

[0073] In the configuration of the multi-joint body 12e according to Figure 17 it can be seen that not only the seat part 14 but also the backrest part 18 has plug-in connection elements 104, 106 configured as pin receptacles. The corresponding plug-in connection parts 104, 106 are provided on the opposing sides of the seat part 14 or the backrest part 18. The seat element 108 and the backrest element 110 can be easily inserted into the plug-in connection elements 104, 106 with corresponding plug-in connection elements 112, 114 configured as pins, so that they can be easily arranged on the multi-joint body 12e thereby. The seat part 14 and the backrest part 18 can each have four plug-in connection elements 104 or 106 in particular.

[0074] In the embodiment of the multi-joint body 12f according to Figure 18 it can be seen that the armrests 120, 122 are arranged on the backrest part 18. In particular, the armrests 120, 122 are integrally formed with the backrest part 18. The armrests can be injection-molded onto the backrest part 18. The armrests 120, 122 and the upper section 124 of the backrest part 18 together form a U-shaped shape. The backrest 20, which is only schematically shown here, can be fixed to the section 124 of the backrest part 18.

[0075] Furthermore, it should be noted that the seat 16 can be inserted into the opening 126 of the seat part 14 with a corresponding projection or can be fixed to the seat part 14 through the opening 126 by means of bolts. In Figure 18 the footrest 128 is also shown, which is connected to the support part 22 by a strut 130.

[0076] Figure 19Shows the central unit 10e of a chair, in particular an office chair, having a multi-joint body 12g. The multi-joint body 12g includes a seat portion 14 for the seat 16, a backrest portion 18 for the backrest 20, a support portion 22 for the strut, and a front portion 24. The seat portion 14 is connected to the backrest portion 18 by a joint 26 configured as a solid joint. The backrest portion 18 is connected to the support portion 22 by a joint 28 configured as a solid joint. The support portion 22 is connected to the front portion 24 by a joint 30 configured as a solid joint. The front portion 24 is connected to the seat portion 14 by a joint 32 configured as a solid joint. The material thickness of the joints 26, 28, 30, 32 is less than the material thickness of the seat portion 14, the backrest portion 18, the support portion 22, and the front portion 24. The seat portion 14, the backrest portion 18, the support portion 22, and the front portion 24 are configured to be rigid. The joints 26, 28, 30, 32 are configured to be less rigid, i.e., flexible, in particular elastic. The material thickness of the joints 26, 28, 30, 32 can be the same or different. In any case, two joints can also have the same material thickness.

[0077] Both the seat portion 14 and the support portion 22 include mounting members 14a, 22a or retaining means for a spring device, which spring device includes at least one spring element. The mounting members are in the shape of dove tails. They also serve as guides for the spring elements, so that the spring elements can be inserted by pushing them from the side without the use of tools.

[0078] Figure 20 Shows the multi-joint body 12g with a spring element 38a having a spring device 36a mounted. The spring device 36a is used to provide sufficient resistance to the backward tilting of the backrest. The spring device 36a is arranged between the seat portion 14 and the support portion 22. To adjust the spring force, a plurality of spring elements 38a can be mounted adjacent to each other in the mounting members 14a, 22a. Alternatively or additionally, the material thickness and / or width and / or material of the spring element 38a can be changed to adjust the spring force, thereby adjusting the central unit 10e for different user weights. Thus, the spring element 38a can be replaced with a different spring element 38a to adjust the spring force, or different spring elements 38a can be combined.

[0079] Figure 21 Shows a side view of the spring element 38a that can be detached from the multi-joint body 12g. The spring element 38a has an S-shaped structure. The ends 38a’, 38a” are wider than the rest of the spring element 38a and have a structure complementary to the mounting members 14a, 22a. They are adapted to the mounting members 14a, 22a.

[0080] Figure 22A perspective view showing the spring element 38a is presented. A plurality of spring elements 38a can be provided, and the user can install an appropriate number of spring elements 38a to adjust the chair with the central unit 10e according to their own needs.

Claims

1. A central unit (10, 10a, 10b, 10c, 10d, 10e) for a chair, in particular an office chair, characterized in that The central unit comprises a multi-jointed body (12, 12a, 12b, 12c, 12d, 12e, 12f, 12g), the multi-jointed body comprising a seat part (14) for a seat (16), a backrest part (18) for a backrest (20), a support part (22) for a support column (130) for a footrest (128), and a front part (24, 24a) arranged between the seat part (14) and the support part (22), wherein the multi-jointed body (12, 12a, 12b, 12c, 12d, 12e, 12f) comprises at least three joints (26, 28, 30, 32), which respectively connect two of the parts in an articulated manner.

2. The central unit according to claim 1, characterized in that At least one of the joints (26, 28, 30, 32), in particular at least three joints, preferably four joints, is designed as a solid joint.

3. A central unit according to any one of the preceding claims, characterized in that The solid joint is constructed integrally with the parts connected thereby.

4. A central unit according to any one of the preceding claims, characterized in that The multi-jointed body (12, 12a, 12b, 12c, 12d, 12e, 12f, 12g) is constructed in one piece.

5. Central unit according to any of the preceding claims, characterized in that The multi-jointed body (12, 12a, 12b, 12c, 12d, 12e, 12f, 12g) consists of plastic, in particular glass-fiber-reinforced plastic, preferably glass-fiber-reinforced polyamide.

6. Central unit according to any of the preceding claims, characterized in that Exactly one of the joints (28) is designed as a hinge with a swivel pin (54).

7. A central unit according to any one of the preceding claims, characterised in that The front part (24a) is designed to be flexibly elastic.

8. A central unit according to any one of the preceding claims, characterised in that A spring assembly (36, 36a) is arranged between the seat portion (14) and the support portion (22).

9. The central unit according to claim 8, characterized in that The spring assembly (36, 36a) has at least one spring element (40, 38a) which can be activated and deactivated or is arranged on the multi-jointed body (12g).

10. Central unit according to any of the preceding claims, characterized in that A limiting assembly is provided for limiting the maximum relative movement between the seat portion (14) and the backrest portion (18).

11. Central unit according to any of the preceding claims, characterized in that A manually operable locking mechanism is provided for locking the relative positions of the seat portion (14) and the backrest portion (18).

12. Central unit according to any of the preceding claims, characterized in that A manually operable seat tilt limiter is provided.

13. A central unit according to any one of the preceding claims, characterised in that A pin (68) is arranged on the backrest part (18) and is guided in a guide groove (66) of a guide part (64) arranged on the support part (22).

14. Central unit according to any of the preceding claims, characterized in that A lock (70) is pivotably arranged on the guide section (64), the lock having a stop (76) for the pin (68) and a locking receptacle (78) for the pin (68).

15. A chair, in particular an office chair, having a central unit (10, 10a, 10b, 10c, 10d) according to any of the preceding claims.

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