EP1039816B1 - Chair mechanism - Google Patents

Abstract

The chair mechanism is configured as a so-called synchronizing mechanism in order, in the case of an adjustment in inclination of the rear support (4), to achieve simultaneous, harmonic adjustment of the seat panel (8). The underframe is positioned on a height-adjustable pneumatic spring (13,14). For the synchronized movement, use is made of a mechanical torsion spring, preferably a rubber spring, and a further mechanical spring, preferably a helical spring, is arranged parallel thereto, with accumulative effect in relation to the resistance of the torsion spring. The strength of the torsion spring can be adjusted. The positioning of the axes of rotation (A1-A4) is of considerable importance for the kinematics. The chair can be adjusted from an assembly position, where the springs can be inserted in a state in which they are relieved of stressing, via the vertical position into the inclined position. The most prominent advantages of the chair mechanism are the large opening angle between the seat panel (8) and backrest in the inclined position, the adjustable degree of stiffness, and the compliant seat shell.

Description

Field of application of the invention

The invention relates to a chair mechanism, in particular for a swivel chair Office chair with a gas spring arranged vertically in the base for adjustability the height of the seat. The chair mechanics causes that with the back Incline the back support, which the user does by shifting weight initiated, the seat plate is lowered synchronously.

State of the art

Mentally active people spend the majority of their working hours in sitting position. Specially prevented writing posture over several hours at a workstation leads to considerable stress on the Skeletons, the muscles and tissues of the back as well as the neck area. This resulted in a variety of efforts, the geometry of chairs and improve their mechanics to suit the user of the respective sitting posture relieve more effectively. A decisive development step was made with synchronous mechanisms, where when adjusting the back support, over Lever and hinge connections, the seat follows synchronously and moves at every inclination position the back support has an ergonomically adapted position Seat adjusts. Such a synchronous mechanism is in CH-A-629 945 disclosed. This mechanism allows the user to get out of the upright posture by shifting body weight backwards and pushing against the cushioned cushioned backrest in a reclined relaxation position - e.g. for a long call - to go. The seat follows reclining backrest so that the user leans backwards, relieving rest position results. These chairs allow easy and frequent switching to a relaxing user position.

Mostly, however, office work is not in a relaxed, reclined position afford, but in a forward bent position to get in touch with those on the Work table lying documents. To the pressure of the seat against the Lessen lower leg and allow the user to straighten his spine Mechanisms have been proposed in which, according to forward inclination due to the weight shift a lowering of the front Seat is done. In addition, one tried through special design the backrest with a lumbar support and mostly lifting at the same time the back seat the harmful backward rolling of the pelvis and to prevent curved back posture. However, the backrest only supports if you sit completely in the chair and emphasize contact with the backrest Has. In reality, there is no support for the back area, since most of the time is sitting near the front edge of the chair. Thus EP-B-0 592 proposed 369 a synchronous mechanism in front, where in bent and upright posture the seat lowers in the front and when the user shifts weight into one backward tilted relaxation position slides.

The springs used are more important for the function of a chair mechanism Importance. To execute the synchronous movement between Back support and seat plate are often used gas springs, which for Improvement of the kinematics are often coupled with helical compression springs (e.g. CH-A-629 945). However, gas pressure springs have several disadvantages; they increase The cost of the entire chair is substantial and must be achieved a favorable movement sequence coupled with mechanical springs be what makes the construction more expensive and complicated. Furthermore have Only a limited amount of gas pressure springs due to the wear on the seals Life. WO-A-92/03072 has therefore been proposed for Suspension during the synchronous movement a mechanical spring in the form of a Insert torsion bar.

WO-A-93/25121 describes the use of a rubber spring with an embedded one Steel core and an outer steel jacket proposed, being the inner steel core is subjected to torsion. The use of such Rubber spring brings too little stiffness in the normal position of the seat whereby this sitting position does not have the desired stability to the full extent. This does not succeed with the conceived positioning of the Rotation axes, i.e. an approximately central, swing-shaped suspension of the seat plate and the articulation of the seat plate in the rear area.

Object of the invention

With the steady increase in computer workstations one becomes more upright Sitting posture with permanently tense neck area forced to follow what is happening on the screen. Thus changes for many People the typical work posture and consequently there are changing demands the mechanics of a chair to optimize its kinetic Behavior. The previous synchronous mechanisms are advantageous for users, whose work tasks allow a frequent change of attitude, namely between leaning forward, sitting upright and leaning back. For lasting The known constructions are sitting at a computer workstation but not yet ideal.

The invention is therefore based on the object of creating a mechanism with the one sitting position that is largely stress-free and leaned back with a wide opening angle between the seat and back surface as permanent working posture is designed. One must be in the front sitting position effective support of the lumbar area can be realized while in the back leaning seated position a partial sinking into the chair relaxed sitting should offer without having to change the perspective significantly. In the Relaxed, reclined seating position should the mechanics as well as the whole Chair structure gives the user a certain amount of mobility in the chair enable and provide noticeable support for the shoulder. The seat and the backrest should be adjustable in height. The is also desired Adjustable seat depth and lumbar support intensity as well as a adjustable neck support. In series, the chair should be rational and closed cheap costs can be produced. Finally, the construction enable a design that corresponds to the taste of the time.

Overview of the invention

The chair mechanism of the seat rests on a base frame with a foot resting on the floor - usually a standardized five-armed star base - and a vertically arranged gas spring with a telescopically extendable piston rod for height adjustment of the chair. The seat with the seat support attached at the bottom is placed as a structural unit on the piston rod. The horizontal main axis of rotation with the torsion spring positioned thereon, preferably a rubber spring, extends through the seat support. The back support, which can be pivoted about the main axis of rotation against the resistance of the torsion spring, acts on the torsion spring. The chair also has a seat plate for receiving a seat cushion with the possible interposition of a cushion carrier. The seat plate is articulated on the one hand on a horizontal rear axis of rotation on the back support and on the other hand connected to a joint on a horizontal front axis of rotation. The joint is connected to the seat support on a horizontal, fixed axis of rotation. The back support and seat plate perform synchronous position changes when swiveling between a vertical position and an inclination position.

The essence of the invention is that parallel to the torsion spring and in another mechanical adding effect to the resistance of the torsion spring Spring is provided. The parallel spring is preferably a coil spring, which can be separated into two symmetrically arranged parts. critical for the properties of the mechanics are also the positions of the Rotation axes, which are all below the seat plate. The front axis of rotation - as a connection between the seat plate and the joint - is close to the front edge the seat plate provided, the front axis of rotation in the radius and Pitch circle around the fixed axis of rotation - as a connection between the joint and Seat support - can be swiveled. The rear axis of rotation - as a connection between Seat plate and back support -, is close to the rear edge of the seat plate, whereby the rear axis of rotation in the radius and pitch circle around the main axis of rotation is pivotable. The main axis of rotation is between and below the front and the rear axis of rotation.

The fixed axis of rotation should preferably lie above the plane of the main axis of rotation and, in the vertical position of the chair, the front axis of rotation should be approximately perpendicular to the fixed axis of rotation. In the maximum inclination position , the rear axis of rotation should be able to be lowered at least close to the plane of the main axis of rotation. In the vertical position of the chair, the front axis of rotation is in front of the main axis of rotation in front of the fixed axis of rotation. Starting from this chair position, the horizontal distance between the fixed axis of rotation and the main axis of rotation and between the main axis of rotation and the rear axis of rotation is in a size ratio of 1: 2 in some areas. In the maximum inclination position, the seat plate is inclined in the range of 15 °.

The conventional torsion spring consists of the inner steel core, the rubber layer firmly attached to the steel core and the one on the Rubber layer of firmly attached outer steel jacket. Through the steel core, which lies on the main axis of rotation, extends a polygonal passage, in a complementary polygonal driver rod is used. The driver bar is with its outer ends in the polygonal free ends of the forked back carrier with two support arms. On the outer steel jacket of the torsion spring is to adjust it Preload an adjustable tension element attached.

The parallel spring is arranged on the front axis of rotation and is supported as Coil spring with one end below the seat plate while the other End of the coil spring is fixed to a preload pin. The preload bolt lies on the front axis of rotation, is firmly inserted into the joint and is rotatably inserted in the front on the underside of the seat plate Joint approaches. Joint, preload bolt, coil spring and the pair Joint approaches are available twice and are symmetrical to the torsion spring arranged.

The back support has between its two support arms one below the Seat plate arranged bearing pan through which the rear axis of rotation extends and on the, stuck on an axis rod, on the underside of the seat plate existing rear joint approaches are articulated. Above the seat plate combine both support arms in a U-shaped guide that the height-adjustable recording of a back support is used. The seat support exists first from the middle sleeve body with the continuous main axis of rotation to accommodate the torsion spring. At the back of the sleeve body, the Push-on flange with its tapered bore running on the vertical axis to be placed on the piston rod of the gas spring. At the front of the sleeve body the bearing flange starts. This has one on the fixed axis of rotation and through hole running parallel to the main axis of rotation Inclusion of an axle rod on which the joints on both sides of the bearing flange are arranged. For attaching the tension element to the outer steel jacket the torsion spring has a recess in the sleeve body.

The back support initially consists of the lower base spar for insertion into the guide on the back support and one on the base spar upward extending central spar. Two symmetrical between base spar and The central strut is arched and horizontally extending lumbar extensions are used for Hold and clamp a flexible back shell. Above the central stringer two Y-shaped support arms go off. The free ends of the Lumbar brackets have through holes for attaching one Back shell on, while the ends of the support arms in on the back shell existing pockets are inserted. An adjustable incline Headrest can be attached to the backrest. The tension of the Back shell in the lumbar area can be placed in the lumbar extension arranged eccentrics can be set variably. On the user side is the back shell is completely covered with a cover on the back Partial side, with a trained pocket and to fix the cover Quick fasteners are provided. The headrest can be in a desired one Set angle of attack and selectable height.

The essential advantages of the chair mechanism according to the invention are the large opening angle between the seat plate and the backrest in the inclined position , the adjustable responsiveness of the chair in the event of weight shifting by the user, and the soft, flexible seat shell, so that the relaxing inclined position can be assumed as a continuous working posture. The lumbar support, which can be adjusted in intensity, the selectable height adjustment of the backrest and the headrest, which can be variably adjusted in the angle of attack, result in a high level of seating comfort, which is particularly useful when working with a keyboard and at VDU workstations. In the reclining position, the front edge of the seat plate lowers and the entire seat travels deeply backwards. The optimal seat depth gives the user effective support for his back and shoulders without losing eye contact with his screen and straining the neck muscles. The preferably mesh-like covering of the back shell - and possibly also the head cushion and armrests - creates a pleasant seating climate and a decorative effect.

Brief description of the attached drawings

Figur 1A:

einen erfindungsgemässen Stuhl als Ganzes in Vertikalposition und seitlicher Perspektivansicht;

Figur 1B:

den Stuhl gemäss Figur 1A in Perspektivansicht von hinten;

Figur 1C:

den Stuhl gemäss Figur 1A als Explosivdarstellung in Baugruppen mit Armlehne;

Figur 2A:

einen Rückenträger, eine Rückenstütze und eine Kopfstütze in Explosivdarstellung;

Figur 2B:

den Rückenträger und die Rückenstütze aus Figur 2A mit bespannter Rückenschale;

Figur 3A:

die Anordnung unter der Sitzplatte auf der Höhengasfeder mit Rückenträger;

Figur 3B:

die Anordnung gemäss Figur 3A als Explosivdarstellung;

Figur 3C:

die Baueinheit aus Rückenträger, Sitzplatte und Gummifeder auf die Höhengasfeder aufgesetzt in Vertikalposition im Teilschnitt;

Figur 3D:

die Baueinheit gemäss Figur 3C im perspektivischen Teilschnitt;

Figur 4:

die Gummifeder mit Gehäuse aus Figur 3A in Explosivdarstellung;

Figur 5:

die Baueinheit gemäss Figur 3C im Bewegungsablauf zwischen der Montageposition über die Vertikalposition zur Neigungsposition;

Figuren 6A bis 6D:

die Funktionsweise der Verstellung der Sitztiefe

Figur 6A:

einen Schnitt aus Figur 3A auf der Linie A-A mit arretiertem Stellhebel;

Figur 6B:

die Darstellung gemäss Figur 6A mit gelöstem Stellhebel;

Figur 6C:

einen Schnitt aus Figur 3A auf der Linie B-B mit maximal nach vorn gezogenem Polsterträger und arretiertem Stellhebel; und

Figur 6D:

die Darstellung gemäss Figur 6C mit maximal nach hinten geschobenem Polsterträger und gelöstem Stellhebel.

Show it:

Figure 1A:

an inventive chair as a whole in a vertical position and side perspective view;

Figure 1B:

1A in perspective view from behind;

Figure 1C:

the chair according to Figure 1A as an exploded view in assemblies with armrests;

Figure 2A:

a back support, a backrest and a headrest in an exploded view;

Figure 2B:

the back support and the back support from FIG. 2A with the back shell covered;

Figure 3A:

the arrangement under the seat plate on the gas spring with back support;

Figure 3B:

the arrangement according to Figure 3A as an exploded view;

Figure 3C:

the unit consisting of back support, seat plate and rubber spring placed on the vertical gas spring in the vertical position in partial section;

Figure 3D:

the assembly of Figure 3C in perspective partial section;

Figure 4:

the rubber spring with housing from Figure 3A in an exploded view;

Figure 5:

the assembly according to Figure 3C in the sequence of movements between the mounting position on the vertical position to the tilt position ;

Figures 6A to 6D:

how the seat depth adjustment works

Figure 6A:

a section of Figure 3A on line AA with locked lever;

Figure 6B:

the representation according to Figure 6A with released lever;

Figure 6C:

a section of Figure 3A on the line BB with the cushion carrier pulled forward at most and the locking lever locked; and

Figure 6D:

the representation according to FIG. 6C with the cushion support pushed to the rear and the actuating lever released.

embodiment

With reference to the accompanying drawings, the detailed is given below Description of an embodiment of the chair mechanism according to the invention.

The following definition applies to the entire further description: are in one figure contain reference numerals for the sake of graphic clarity, but in immediately associated description text is not explained, is mentioned on their mention in previous or later figure descriptions. In the interest of clarity, the repeated designation is used mostly omitted from components in the following figures, if in the drawing It is clearly recognizable that these are "recurring" components is.

Figures 1A and 1B

The entire chair is divided into two levels, the base U known per se and the seat S placed on the base U , which embodies the invention. The base frame U consists of a typical five-armed star base 1 with rollers 11 attached to the ends of the arms 10 , which rest on the floor. The center of the star base 1 is formed by a sleeve piece 12 in which a gas spring 13 is inserted vertically. A telescopically extendable piston rod 14 protrudes from the gas spring 13 on the axis A , on which the seat support 2 , which is the base part of the entire seat S , is placed. The seat S can be rotated about the axis A and its height can be adjusted with the extension or retraction of the piston rod 14 on the axis A.

The seat support 2 consists of a middle sleeve body 20 , a rearward projecting plug-on flange 21 and a front-mounted bearing flange 22. The horizontal main axis of rotation A1 extends through the sleeve body 20 , on which a conventional rubber spring 3 is received. The vertical axis A runs through the push-on flange 21 and an axis of rotation A2 parallel to the main axis of rotation A1 runs through the bearing flange 22 . The chair is also composed of a back support 4, a backrest 5, a headrest 6, a back shell 7, a seat plate 8 and the armrests, not shown, which can be used as an option. A cushion support 80 is arranged on the seat plate 8 for the immediate reception of the seat cushion 801 . The seat support 2 with the inserted rubber spring 3 are positioned below the seat plate 8 , the main axis of rotation A1 being quasi parallel to the front edge 810 of the seat plate 8 .

On the main axis of rotation A1 , the back support 4 is fastened, which, with its two support arms 40, attaches to both sides of the rubber spring 3 in a fork-like manner and extends upward from below the seat plate 8 at a distance from the rear edge 811 of the seat plate 8 . Above the level of the seat plate 8 , the support arms 40 unite to form a guide 41 in which the height-adjustable back support 5 is held with its lower base beam 50 . The set height is fixed by means of a clamping screw 42 passing through the guide 41 of the back support 4 . Above the base spar 50 , two lumbar cantilevers 51 extend symmetrically, approximately horizontally and forming an arc, which are attached with their outer ends to the back shell 7 in the lower lumbar region 70 thereof. The lumbar extension 51 encompasses the lumbar region 70 of the back shell 7, wherein vertical expansion slots could be provided in the lumbar region 70 to increase the elasticity of the back shell 7 . Above the lumbar brackets 51 , the back support 5 has the shape of a letter with a lower central spar 52 and two wing-like support arms 53 , the ends of which are inserted into pockets 710 , which are located in the upper corners on the rear side of the back shell 7 . Where the support arms 53 branch off from the central strut 52 , the vertical strut 60 of the headrest 6 is attached. At the top of the vertical strut 60 , a head cushion 61 facing the back of the user's head is held, the inclination of the vertical strut 60 being adjustable.

Below the seat plate 8 near the front edge 810 and near the rear edge 811 are paired spaced joint approaches 820,821 . On the bearing flange b of the seat support 2 , joints 9 are arranged on its axis of rotation A2 , which overlap with the horizontal axis of rotation A3 on the front joint attachments 820 . On a horizontal axis of rotation A4 , the rear joint attachments 821 , which are located near the rear edge 811 of the seat plate 8, are each connected to a support 40 of the back support 4 . If the back support 4 and back support 5 are inclined to the rear, the seat plate 8 is lowered and carried synchronously to the rear.

To cover the back shell 7 , a cover 73 is provided, which has a pocket 730 facing backwards and open at the bottom. The lower edge 72 of the back shell 7 is inserted into this pocket 730 up to approximately the lumbar region 70 . The cover 73 completely spans the front of the back shell 7 and has an upper part 731 for folding over the upper edge 71 and two lateral parts 732 for folding over both side edges of the back shell 7 . Recesses 733 run between the upper part 731 and the two lateral parts 732 , so that, when folded over, the pockets 710 provided on the back shell 7 remain accessible for inserting the ends 530 of the support arms 53 . Between the upper section 731 and the respectively adjacent lateral section 732 , a quick-action connection 734 - for example a hook or Velcro connection - is provided, which engages under the support arms 53 . The lateral parts 732 also do not span the ends of the lumbar brackets 51 fastened to the back shell 7 , as a result of which the middle field of the back shell 7 remains uncovered at the rear. With detached quick- connect connections 734 , the cover 73 can therefore be quickly fitted onto the back shell 7 during assembly or removed just as quickly for the purpose of cleaning or renewal.

Figure 1C

Disassembled into larger assemblies, you can see the base frame U with the star foot 1 and the gas spring 13 inserted vertically and centrally for the height adjustment of the seat S. From the seat S you can see the seat plate 8 below which the essential part of the chair mechanism is located and after protruding back support 4 is attached. The seat plate 8 is placed on the cushion plate 80 which is adjustable in the seat depth and which carries the seat cushion 801 and a cover 802 spanning it. Also shown are the back shell 7 and the headrest 6 with the head cushion 61 and the vertical strut 60 which extends downward for attachment to the backrest 5 . It is practical and decorative to provide the head cushion 61 with a quickly exchangeable cover 610 , which is optically effective, for example a mesh covering.

To perfect the chair, it can be equipped with laterally arranged armrests 65 , the support arms 66 of which are arranged in a bow-shaped manner and are preferably also attached below the seat plate 8 . At the top, the support arm 66 has an adjusting device 67 for adjusting the height and the inclination of the inserted armrests 68. The armrest 68 has a vertical support strut 69 projecting through the adjusting device 67 , a support plate 680 and the cushion 681 arranged thereon. This cushion 681 is preferably provided with a cover 682 , for example also a decorative mesh covering.

Figure 2A

Between the underneath of the guide 41 on the back support 4 forked accreting two support arms 40 is a, box-shaped arranged upwardly open bearing cup 43 in its two side walls 430 - are two mutually aligned holes 431 provided on the - these are on the carrier arms 40 at Axis of rotation A4 are positioned. A front and a rear transverse wall 432, 433 extend between the side walls 430 . The rear joint projections 821, which originate from the seat plate 8 , project into the bearing socket 43 . An axle rod 44 is pushed through the bores 431 in the bearing socket 43 and in the complementary bores present in the joint extensions 821 , so that the seat plate 8 is rotatably fastened to the back support 4 on the axis A4 . To fix the axle rod 44 , for example, a lateral screw connection 440 , which is supported from the outside against the side walls 430, is used .

The front transverse wall 432 faces the free ends of the support arms 40 through which the main axis of rotation A1 runs, while the rear transverse wall 433 lies opposite the front transverse wall 432 and faces the guide 41 of the back support 4 . A recess 435 is worked into the rear transverse wall 433 from above in order to receive a pretensioning wedge 45 (see FIG. 3B), the function of which will be explained later. The free ends of the support arms 40 each have a continuous inner polygon 401 on the main axis of rotation A1 , a driver rod 46 made of polygonal profile being inserted in a rotationally stable manner through both inner polygon 401 and the rubber spring 3 . The driver rod 46 is fastened, for example, with a screw connection 460 , which is supported laterally from the outside against the support arms 40 .

For the passage of the clamping screw 42 , the U-profiled guide 41 , which is open towards the seat S , has a through hole 410 and, complementarily thereto, an elongated hole 500 with a vertical extension is present in the base spar 50 of the back support 5 . The height adjustment of the back support 5 can thus take place within the elongated hole 500 . The lumbar extensions 51 , which extend to both sides of the back support 5 , have through holes 510 at their free ends. For the interaction with the lumbar arms 51 , two eccentrics 55 are provided, which consist of a rotary knob 550 to be gripped , a cylinder section 551 which can be inserted into the through bores 510 and a clamping bolt which projects eccentrically through the cylinder section 551 . By turning the eccentric 55 , the distance between the two clamping bolts is changed and the tension in the lumbar region 70 of the back shell 7 can thus be adjusted. With softer tension, the lumbar region 70 of the back shell 7 becomes more resilient for the user. The clamping bolts engage in the back shell 7 , so that the back support 5 and the back shell 7 are firmly connected to one another.

On the central stringer 52 of the backrest 5 there is a screw hole 520 near the branching of the support arms 53 , which is used to fasten the headrest 6 . The free ends 530 of the support arms 53 could also have through holes in order to be able to use screws for fastening to the back shell 7 . However, the ends 530 are advantageously inserted into pockets 710 , which are located on the rear side of the back shell 7 , in the upper corners.

Figure 2B

To improve the air conditioning of the back shell 7 , this is covered with a quickly exchangeable, decorative cover 73, for example a net. Due to the tension of the cover 73 , it does not rest on the central region of the back shell 7 , which is concavely curved, as seen by the user, without load. Thus, the cover 73 lifts off the back shell 7 as soon as the user no longer exerts pressure. This allows both the back shell 7 and the cover 73 to breathe and release absorbed moisture. In addition, there is a decorative optical effect. The side walls 430 of the bearing pan 43 are contoured in the manner of a ledge, so that the support arm 66 of the armrest 65 placed there is given a particularly good hold by positive locking and stop.

Figures 3A and 3B and 6A to 6D

This pair of figures serves only to illustrate the structure of the chair mechanism and, in connection with the sequence of figures 6A to 6D, to describe the adjusting device for the seat depth. A double-angled lever 803 is arranged in the seat plate 8 , the handle part 804 of which protrudes laterally for actuation by the user and the plate-shaped locking part 805 comes to rest in a recess 812 in the seat plate 8 . Beneath the locking part 805 is a spring tongue 806, which is supported on the seat plate 8 and thus presses the locking part 805 upwards with pretension. On the locking part 805 there are three lugs 807 projecting upwards in a row for engaging in a complementary hole pattern 800 below the cushion support 80 (see FIGS. 6A to 6D). When the lever 803 is actuated, the lugs 807 and the perforated grid 800 disengage, so that the cushion support 80 can be displaced in the seat depth in steps from a maximum front position (see FIG. 6C) to a maximum rear position (see FIG. 6D) is. Such a setting range could, for example, comprise 50 mm in 5 steps of 10 mm each.

The seat plate 8 has laterally projecting, cut-down edges 814 , which are underlaid by the upholstered support 80 with angled claws 808 arranged on its underside, so that the support 80 is guided in the seat depth on the seat plate 8 . In the front area, the cushion support 80 has a stop edge 809 on its underside, which abuts the front edge 810 of the seat plate 8 when the cushion support 80 is at the maximum rear position. To limit the maximum front position, two stop cams 813 are provided on the upper side of the seat plate 8 , near the rear edge 811 thereof, against which the fully extended cushion carrier 80 abuts (see FIGS. 3A and 3B).

Figures 3C to 4

The seat plate 8 according to FIGS. 3C and 3D is a simplified version compared to FIGS. 3A and 3B without the possibility of adjusting the seat depth. The rubber spring 3 has the shape of a roller and is constructed in three layers. An innermost steel core 30 has a polygonal passage 300, for example hexagonal, located on the main axis of rotation A1 for the positive reception of the driving rod 46 . The driver rod 46 inserted in the rubber spring 3 is seated on both sides in the inner polygon 401 at the free end of the support arms 40 in a rotationally stable manner . A rubber layer 31 is applied to the steel core 30 and is surrounded by an outer steel jacket 32 . Carriers 320 protrude from the steel jacket 32 into the rubber layer 31 . This rubber spring 3 is located in the sleeve body 20 of the seat support 2, and in order to reduce the friction with the inner wall of the sleeve body 20, 32 sliding rings 33, for example made of plastic, can be applied to the steel jacket. The plug-on flange 21 pointing rearward on the seat support 2 has a vertical conical bore 210 on the axis A, into which the upper part of the piston rod 14 which can be extended from the gas spring 13 is inserted. The valve rod 15 protrudes axially from the piston rod 14 , and when it is actuated, depending on the load on the seat S , the piston rod 14 extends or retracts. The valve rod 15 is actuated in a conventional manner via a shift lever, not shown, which is usually provided under the seat plate 8 .

The bearing flange 22 , through which the through-bore 220 extends on the axis of rotation A2, is arranged facing the plug-in flange 21 and points forward from the sleeve body 20 . Between the plug-on flange 21 and the bearing flange 22 , the sleeve body 20 has a recess 200 for inserting a tension element 23, which is fastened on the outer steel jacket 32 , for example by a screw connection 230 . A tension bolt 24 is suspended in the tension element 23 , the tension bolt 24 projecting through the bearing flange 22 and a handwheel 26 supported on the bearing flange 22 being screwed onto the tension bolt 24 . When the handwheel 26 is screwed on, the tension element 23 is pulled towards the bearing flange 22 and the rubber spring 3 is thus preloaded more.

On the axis of rotation A2, on both sides of the bearing flange 22 , the rotatable joints 9 are arranged, which overlap the axis of rotation A3 and there are rotatably connected to the front joint extensions 820 on the underside of the seat plate 8 . The joint projections 821 at the rear on the underside of the seat plate 8 are articulated on the axis of rotation A4 in the bearing socket 43 , which sits between the support arms 40 of the back support 4 . The driver rod 46 inserted in the rubber spring 3 is seated on both sides in the inner polygon 401 at the free end of the support arms 40 in a rotationally stable manner.

The seat plate 8 has a depression 83 consisting of two sections 830 , 831 . A recess section 830 is worked in from above, which, viewed from the front edge 810 of the seat plate 8 , lies in front of the bearing socket 43 . A recessed section 831 , which is worked in from below, adjoins the recessed section 830 and is positioned above the bearing socket 43 between the joint attachments 821 . Thus, a locking slide can be used 84, into the recess portion 830 by a spring 86 loaded always partially in the recessed portion 831 inside is slid, so that the locking slide 84, the seat plate 8 by resorting to the front transverse wall 432 of the bearing cup 43 touches (FIG 3C shows the unlocked state). The vertical position of the chair is locked. Even with massive pressure by the user against the back support 5 or the back support 4 , the back support 4 with the back support 5 attached remains in a quasi vertical, prestressed vertical position. A return mechanism 85 attaches to the locking slide 84 and can be actuated with a switching lever 87 in order, if necessary, to pull the locking slide 84 back against the action of the spring 86 into the unlocked position shown in FIG. 3C. Only now can the back support 4 and back support 5 be moved backwards into the tilt position. The locking slide 84 remains in the retracted state by exceeding a dead center of the return mechanism 85 , ie the back support 4 remains movable. Pre-pivoting of the back support 4 about the main axis of rotation A1 when the seat S is completely relieved is prevented by the pretensioning wedge 45 , which is placed in the recess 435 on the rear transverse wall 433 of the bearing socket 43 and presses against the seat plate 8 from below.

FIG. 3D also shows that bevels are provided on both sides near the rear edge 811 of the seat plate 8 ; attach the armrests here too. In addition to the two front joint extensions 820 described so far on the underside of the seat plate 8, there are two further inner joint extensions 822 , which are also on the axis of rotation A3 and are each offset in the direction of the seat support 2 , so that the joint extensions 820 are on the outside, the two inner joint extensions 822 face each other and each distance from the associated outer joint attachment 820 . In each case on the outside of the outer joint attachment 820 , a joint 9 is directed with its joint leg 90 pointing towards the axis of rotation A3 , in which there is a through hole 900 on the axis of rotation A3 . Bores aligned with the through bore 900 are also provided lying on the axis A3 in the joint projections 820 , 822 , as a result of which a pretensioning bolt 88 can be used as the axis on the axis of rotation A3 , which can be inserted from the joint leg 90 - with its head 880 firmly seated therein - through the extends two associated joint approaches 820 , 822 . At the shaft end 881 , the pretensioning pin 88 has a transverse slot 882. On the pretensioning pin 88 inserted, between the pair of articulated lugs 820 , 822, there is a coil spring 89 , which has a bend 890 extending over the spring diameter at one end and a tangential bend 891 at the opposite end having. The tangential bends 891 of the two coil springs 89 each rest on the underside of the seat plate 8 , while the bends 890 extending over the spring diameter are in the transverse slot 882 of the pretensioning bolts 88 .

This adds to the effect of the rubber spring 3, the effect of the two coil springs 89. A user sitting in the chair, whose body weight rests against the back support 4 or the back support 5 - and the locking slide 84 is withdrawn, that is to say unlocked - is simultaneously affected by the effects the rubber spring 3 and the coil springs 89 are supported. The rubber spring 3 and the coil springs 89 are connected in parallel. When the back support 4 is inclined to the rear, the driving rod 46 in the rubber spring 3 rotates against its increasing effect and at the same time the seat plate 8 is carried synchronously, so that the coil springs 89 increasingly twist and thereby tension. To adapt to the individual needs, the entire spring resistance of the parallel arrangement of the coil springs 89 and the rubber spring 3 can be adjusted via the handwheel 26 , with which the position of the tension element 23 and thus the pretension of the rubber spring 3 is determined.

Figure 5

During the assembly of the chair, the pretensioning wedge 45 has not yet been inserted into the bearing socket 43 , so that the back support 4 can be set virtually negatively about the fixed main axis of rotation A1 in the direction of the front edge 810 of the seat plate 8 up to the assembly position P ₀ . This movement is followed synchronously by the seat plate 8, which is lowered in the area of the front edge 810 and raised in the area of the rear edge 811 . There is a movement about the fixed axis of rotation A2 with a lowering of the axis of rotation A3 and a movement about the main axis of rotation A1 with an increase of the axis of rotation A4. In the assembly position P ₀ , the rubber spring 3 and the coil springs 89 can be mounted relaxed. In the relation between the fixed axes of rotation A1 and A2 , the axis of rotation A2 lies above the level of the main axis of rotation A1. The maximum negative angle of attack is reached when the recess 435 in the bearing socket 43 abuts with its upper edge near the rear edge 811 against the underside of the seat plate 8 .

With the insertion of the pretensioning wedge 45 , the chair is brought into the vertical position P ₁ , ie the back support 5 mounted on the back support 4 is approximately vertical and the seat plate 8 has an approximately horizontal position. Since it is fixed, the position of the main axis of rotation A1 and the axis of rotation A2 on the bearing flange 22 of the seat support 2 remains unchanged. The rubber spring 2 and the coil springs 89 are now preloaded. By placing the back support 5 vertically, the back support 4 pivots about the main axis of rotation A1, whereby the axis of rotation A4 lowers. At the same time, the joints 9 pivot about the axis of rotation A2 and the joint legs 90 are positioned approximately perpendicularly, so that the axis of rotation A3 is now slightly raised approximately perpendicularly above the axis of rotation A2 . In the vertical position P _1, the joint legs 90 are preferably slightly inclined, so that the axis of rotation A3 precedes the axis of rotation A2 in the direction of the main axis of rotation A1 . This allows the user to reach the inclination position P ₂ more comfortably by shifting weight without having to brace against the back support 5 . Advantageous is also preferred, ₁ to arrange the variable around the main pivot axis A1 rotation axis A4 in the vertical position P so that which comes to lie near the trailing edge 811 of the seat plate 8 exploiting Dende rotation axis A4 on the skin rotational axis A1 and rotational axis A2, but below the Axis of rotation A3 stands. A return to the assembly position P ₀ with a negative angle of attack is excluded, since the upper edge of the inserted pretensioning wedge 45 abuts against the underside of the seat plate 8 near the rear edge 811 .

The retracted locking slide 84 allows the seat S to be adjusted into the tilt position P ₂ if the user shifts weight sufficiently . Here, the back carrier 4 rotates about the main axis of rotation A1, the axis of rotation A4 lowers to a maximum of the level of the main axis of rotation A1 . At the same time 9 pivot joints about the rotation axis A2, so that the hinge leg 90 inclined to the main axis of rotation A1 are provided and the rotation axis A3 of the main axis of rotation A1 has also approximated both horizontally and vertically, but still about two axes of rotation A1 and A2 is located. The maximum inclination of the seat S in the inclination position P ₂ is limited by the seating of the seat plate 8 in the region of the lower recess section 831 on the front transverse wall 432 of the bearing socket 43 , which acts as a stop in the end position.

Claims (16)

1. Mechanism for a chair, comprising an underframe (U) with a base (1), which is positioned on the floor, and a pneumatic spring (13) which is inserted in said base along a vertical axis (A) and has a telescopically extendible piston rod (14) for adjusting the height of the chair, and also comprising a seat (S) with a seat support (2) which is arranged at the bottom and is positioned on the piston rod (14), wherein:

   a) extending through the seat support (2) is a horizontal main axis of rotation (A1) along which there is arranged a mechanical torsion spring (3), which is adjoined by a rear support (4) which can be pivoted about the main axis of rotation (A1), counter to the resistance of the torsion spring (3);

   b) a seat panel (8) for receiving a seat cushion (801), on the one hand, is articulated on the rear support (4) along a horizontal axis of rotation (A4) and, on the other hand, is connected to an articulation (9) along a horizontal axis of rotation (A3), said articulation (9) being connected to the seat support (2) along a horizontal axis of rotation (A2), as a result of which, as the rear support (4) is pivoted between a vertical position and an inclined position of the chair, a synchronous change in position of the seat panel (8) takes place, characterised in that

   c) provided parallel to the torsion spring (3), and with accumulative effect in relation to the resistance of the torsion spring (3), is a further mechanical spring (89); and

   d) the axes of rotation (A1 to A4) are positioned beneath the seat panel (8) as follows:

   da) the front axis of rotation (A3), as connection between the seat panel (8) and the articulation (9), is in the vicinity of the front edge (810) of the seat panel (8), the front axis of rotation (A3) being pivotable radially over part of a circle about the fixed axis of rotation (A2), as connection between the articulation (9) and the seat support (2);

   db) the rear axis of rotation (A4), as connection between the seat panel (8) and the rear support (4), is in the vicinity of the rear edge (811) of the seat panel (8), the rear axis of rotation (A4) being pivotable radially over part of a circle about the fixed main axis of rotation (A1); and

   dc) the main axis of rotation (A1) is between and beneath the front and the rear axes of rotation (A3,A4).
2. Mechanism for a chair as claimed in claim 1, characterised in that

   a) the fixed axis of rotation (A2) is located above the plane of the main axis of rotation (A1);

   b) in the vertical position of the chair, the front axis of rotation (A3) is located substiantially vertically above the fixed axis of rotation (A2); and

   c) in the maximum inclined position, the rear axis of rotation (A4) can be lowered at least into the vicinity of the plane of the main axis of rotation (A1).
3. Mechanism for a chair as claimed in claim 1 or 2, characterised in that

   a) in the vertical position of the chair, the front axis of rotation (A3) is arranged in front of the fixed axis of rotation (A2), in relation to the main axis of rotation (A1);

   b) in the vertical position of the chair, the ratio of the horizontal spacing between the fixed axis of rotation (A2) and the main axis of rotation (A1) and the horizontal spacing between the main axis of rotation (A1) and the rear axis of rotation (A4) is in the region of 1 : 2; and

   c) in the maximum inclined position, the seat panel (8) is in a sloping position in the region of 15°.
4. Mechanism for a chair as claimed in claim 1, characterised in that

   a) the torsion spring (3) comprises:

   aa) an inner steel core (30),

   ab) a rubber layer (31) which is firmly applied to the steel core (30), and

   ac) an outer steel casing (32) which is firmly applied to the rubber layer (31);

   b) extending through the steel core (30), along the main axis of rotation (A1), is a polygonal through-passage (300) into which a carry-along rod (46) of complementary profile is inserted;

   c) the carry-along rod (46) has its outer ends positioned in the free ends of the rear support (4), the latter being designed in the form of a fork with two support arms (40) and said free ends being provided with a polygonal socket (401); and

   d) fastened on the outer steel casing (32) is an adjustable drawing element (23) for adjusting the prestressing of the torsion spring (3).
5. Mechanism for a chair as claimed in claim 1, characterised in that

   a) the further mechanical spring (89) is arranged along the front axis of rotation (A3) and is supported, as a helical spring (89), beneath the seat panel (8) by way of one end (891), while the other end (890) of the helical spring (89) is fastened on a pretensioning bolt (88); and

   b) the pretensioning bolt (88), located along the front axis of rotation (A3), is firmly inserted into the articulation (9) and is positioned rotatably in front articulation extensions (820,822) provided on the underside of the seat panel (8); wherein

   c) there are in each case two articulations (9), pretensioning bolts (88), helical springs (89) and articulation extensions (820,822), arranged symmetrically in relation to the torsion spring (3).
6. Mechanism for a chair as claimed in claim 1 or 4, characterised in that the rear support (4),

   a) between its two support arms (40), has a bearing bushing (43) which is arranged beneath the seat panel (8), through which the rear axis of rotation (A4) extends and on which, positioned on an axial rod (44), rear articulation extensions (821) provided on the underside of the seat panel (8) are articulated; and,

   b) above the seat panel (8), the two support arms (40) open out in a U-shaped guide (41) which serves for receiving a backrest (5) in a height-adjustable manner.
7. Mechanism for a chair as claimed in claim 1 or 4, characterised in that the seat support (2) comprises:

   a) a central sleeve body (20), with the main axis of rotation (A1) running through it, for receiving the torsion spring (3),

   b) a plug-on flange (21) which adjoins the rear of the sleeve body (20) and has a conical bore (210) which runs along the vertical axis (A) and is intended for positioning on the piston rod (14) of the pneumatic spring (13), and

   c) a bearing flange (22) which adjoins the front of the sleeve body (20) and has a through-passage bore (220) which runs along the fixed axis of rotation (A2), parallel to the main axis of rotation (A1), and is intended for receiving an axial rod on which the articulations (9) are arranged, on either side of the bearing flange (22); wherein

   d) the sleeve body (20) has a cutout (200) for fitting the drawing element (23) on the outer steel casing (32) of the torsion spring (3).
8. Mechanism for a chair according to Claim 6, characterised in that

   a) the backrest (5) comprises:

   b) a bottom, base member (50) for insertion into the guide (41) on the rear support (4),

   c) an upwardly extending central member (52) which adjoins the base member (50),

   d) two lumbar extension arms (51) which extend out horizontally in arcuate form symmetrically between the base member (50) and central member (52) and are intended for securing and tensioning an elastic back shell (7), and

   e) two supporting arms (53) which extend out from the top of the central member (52) and open in the form of a Y; wherein

   f) the free ends of the lumbar extension arms (51) have through-passage bores (510) for fastening the back shell (7);

   g) the supporting arms (53) have free ends (530) which are positioned in pockets (710) which are located on the rear side of the back shell (7), preferably in the top corners; and

   h) a headrest (6) which can be adjusted in terms of inclination and height is fastened on the backrest (5).
9. Mechanism for a chair as claimed in claim 8, characterised in that inserted into through-passage bores (510) in the free ends of the lumbar extension arms (51), for the variable tensioning of the back shell (7) in the lumbar region (70) thereof, are rotatable eccentrics (55), of which the eccentrically arranged tensioning bolts engage in the back shell (7).
10. Mechanism for a chair as claimed in claim 9, characterised in that

    a) the eccentrics (55) have a turning knob (550) which is adjoined by a coaxial cylinder portion (551) which is intended for insertion into one of the through-passage bores (510);

    b) the eccentrically arranged tensioning bolt projects through the eccentric (55); and

    c) the tensioning bolt acts, at the same time, as a retaining screw which engages in the back shell (7).
11. Mechanism for a chair as claimed in claim 8, characterised in that

    a) the back shell (7) consists of an elastically compliant material;

    b) may have extension slots in its lumbar region (70); and

    c) may be spanned by a covering (73) at least on the user side.
12. Mechanism for a chair as claimed in claim 11, characterised in that

    a) the covering (73) is semitransparent, preferably mesh-like, and the back shell (7), spanned by the cover on the user side, lifts off partially from the surface of the back shell (7), in the non-loaded state, in order to improve the seat-climate conditions, and has:

    ba) at the bottom, a pocket (730) which is open at the top and is intended for the positioning of the bottom portion of the back shell (7),

    bb) at the top, a top portion (731) for folding over the top edge (71) of the back shell (7),

    bc) on the sides, in each case one lateral portion (732) for folding over the flanks of the back shell (7),

    bd) between the top portion (731) and the lateral portions (732), in each case one cutout (733) for the through-passage of the two supporting arms (53) fastened on the back shell (7); and

    be) quick-action closures, between the top portion (731) and the lateral portions (732), which engage beneath the supporting arms (53).
13. Mechanism for a chair as claimed in claim 8, characterised in that

    a) the headrest (6) comprises a vertical strut (60) and a head cushion (61);

    b) there is provided a securing element (62) which serves for fastening the vertical strut (60) of the headrest (6) on the backrest (5); and

    c) the head cushion (61) is provided with a semitransparent, preferably mesh-like covering (610).
14. Mechanism for a chair as claimed in claim 1, characterised in that, in order to secure the seat (S) in a vertical position (P₁ ), a locking slide (84) loaded by a spring (86) is arranged in the seat panel (8).
15. Mechanism for a chair as claimed in claim 1, characterised in that , in order to adjust the level of the seat (S),

    a) a lever (803), which is retained under prestressing by a spring element (806), is arranged in the seat panel (8); and

    b) securing elements (807) are provided on the lever (803) and a grid arrangement (800) is provided, to complement said securing elements, beneath the cushion support (80), these being in engagement with one another in the non-actuated state and blocking displacement of the cushion support (80), but being capable of being released from one another counter to the pressure of the spring element (806).
16. Mechanism for a chair as claimed in claim 15, characterised in that

    a) the spring element (806) is a spring tongue (806) which extends from the lever (803) and is supported on the seat panel (8);

    b) the securing elements (807) are upwardly projecting noses (807);

    c) the grid arrangement (800) comprises a row of holes (800), as a result of which adjustment in a number of stages is made possible;

    d) the maximum front position and the maximum rear position of the cushion support (80) are bounded by stops (809,810;813); and

    e) the cushion support (80) is guided on the seat panel (8) by groove-like contours (808,814), on the one hand, beneath the cushion support (80) and, on the other hand, in complementary form on the side borders of the seat panel (8).

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