EP0296578B1 - Seat for an office chair or the like, with seat and backrest adjustable by shifting body weight - Google Patents

Abstract

The invention relates to a seat assembly for an office chair or the like, having a seat and back (6, 7) which are adjustable especially by shifting the body and having a cradle (5). The seat and the back are hinged together at their adjoining ends by at least a first articulation (8) and have, at points distanced from the articulation (8), bearing elements (13, 14) which are suspended or guided on the cradle by positive guiding means (10, 11) and are mounted for movement along paths established by the positive guiding means. The articulation (8) is free-floating. The bearing elements (13, 14) are guided by the positive guides (10, 11) independently of one another.

Description

The invention relates to a seat of the type defined in the preamble of claim 1. A seat of this type is known in particular from WO 83/03957.

Seats with seat and / or back parts that are adjustable in particular by shifting body weight are already known in a large number of embodiments (DE-AS's 12 85 701 and 20 26 929, DE-PS's 854421, 2931072 and 3313677, WO 83/03957 and 85/04084, US Pat. No. 4,504,090) and are used above all on office chairs, motor vehicle seats or the like.

Usually, a multi-link mechanism or cam control deflects a compressive force on the seat and back parts in such a way that the back parts are pressed against the back of the user with a certain force. Advantages of such devices over systems with automatic resetting of the back parts by means of spring force can be seen in the fact that the force relationships automatically adjust to the different body weights so that the adjustment of the restoring force is not necessary and that the restoring force increases in proportion to changes in the angle of the back parts. People of different weights are therefore safely supported in every angular position of the back section.

The known systems with automatic return of the back parts are, however, provided with positive controls between the seat and back parts, which only allow a fixed sequence of movements. An individual movement sequence is therefore not possible with these solutions.

The invention has for its object to design the seat of the aforementioned type with simple means so that the angle of inclination of the seat and back parts by body weight shift of the user can be freely selected both individually and relatively to each other within a wide range.

The characterizing features of claim 1 serve to achieve this object.

The invention has the advantage that the angle of inclination of the seat part and the back part are absolutely freely selectable relative to one another and the seat can also be swiveled practically continuously between two extreme positions when the seat part is in a preselected relative position to the back part can. In addition, a large number of intermediate positions can be produced between an extremely upright relative position up to a lying position, so that the user has great freedom of movement and choice.

Further advantageous features of the invention emerge from the subclaims.

• Fig. 1 in einer grob vereinfachten, schematischen Seitenansicht eine erste Ausführungsform des erfindungsgemäßen Sitzes;
• Fig. 2 schematisch eine Anzahl möglicher Sitzpositionen des Sitzes nach Fig. 1;
• Fig. 3 eine schematische Vorderansicht einer zweiten Ausführungsform des Sitzes mit einer gegenüber Fig. 1 veränderten Arretierungsvorrichtung;
• Fig. 4 Einzelheiten der Schwenkmechanik des Sitzes nach Fig. 3;
• Fig. 5 Einzelheiten der Schwenkmechanik nach Fig. 4 in auseinandergeschwenkter Darstellung;
• Fig. 6 und 7 den Fig. 1 und 3 entsprechende Ansichten einer dritten Ausführungsform der Erfindung;
• Fig. 8 schematisch eine vierte Ausführungsform der Erfindung als vergrößerter Schnitt längs der Linie VIII-VIII der Fig. 7;
• Fig. 9 und 10 Schnitte längs der Linien IX-IX und X-X der Fig. 8;
• Fig. 11 und 12 in vereinfachten, der Fig. 8 entsprechenden Ansichten den Sitz nach Fig. 8 bis 10 im verriegelten bzw. entriegelten Zustand und in verkleinertem Maßstab;
• Fig. 13 bis 16 den Fig. 6, 7, 8 und 10 entsprechende Ansichten einer fünften Ausführungsform der Erfindung;
• Fig. 17 und 18 jeweils Schnitte längs der Linien XVII-XVII und XVIII-XVIII der Fig. 16 im verriegelten bzw. entriegelten Zustand und in vergrößertem Maßstab;
• Fig. 19 bis 23 in schematischen, teilweise der Fig. 2 entsprechenden Ansichten verschiedene Sitz- und Liegepositionen sowie Einzelteile einer sechsten Ausführungsform der Erfindung; und
• Fig. 24 bis 26 in schematischen, im wesentlichen Fig. 8 und 15 entsprechenden Ansichten mögliche Abwandlungen der Ausführungsformen nach Fig. 6 bis 18.

The invention is explained in more detail below in connection with the accompanying drawing using exemplary embodiments. Show it:

• 1 shows a roughly simplified, schematic side view of a first embodiment of the seat according to the invention;
• Fig. 2 shows schematically a number of possible seating positions of the seat according to Fig. 1;
• 3 shows a schematic front view of a second embodiment of the seat with a locking device modified compared to FIG. 1;
• Fig. 4 details of the pivot mechanism of the seat of Fig. 3;
• FIG. 5 details of the pivoting mechanism according to FIG. 4 in a pivoted-apart representation;
• 6 and 7 the views corresponding to FIGS. 1 and 3 of a third embodiment of the invention;
• Fig. 8 schematically shows a fourth embodiment of the invention as an enlarged section along the line VIII-VIII of Fig. 7;
• Fig. 9 and 10 sections along lines IX-IX and XX of Fig. 8;
• 11 and 12 in simplified views corresponding to FIG. 8, the seat according to FIGS. 8 to 10 in the locked or unlocked state and on a reduced scale;
• 13 to 16 are views corresponding to FIGS. 6, 7, 8 and 10 of a fifth embodiment of the invention;
• 17 and 18 are sections along lines XVII-XVII and XVIII-XVIII of FIG. 16 in the locked and unlocked state and on an enlarged scale;
• 19 to 23 in schematic views, partially corresponding to FIG. 2, different sitting and lying positions and individual parts of a sixth embodiment of the invention; and
• 24 to 26 in schematic views essentially corresponding to FIGS. 8 and 15, possible modifications of the embodiments according to FIGS. 6 to 18.

1 to 3, a frame 1 with, for example, five star-shaped arms is provided as the supporting element of an office chair, at the ends of which wheels or rollers 2 are rotatably attached. From the center of the frame 1, a tube 3 protrudes vertically upwards, in which an axis 4 of a U-shaped support 5 is rotatably mounted and, if necessary, adjustable in height. The carrier 5 has a crosspiece 5a, preferably arranged perpendicular to the axis 4, and two legs fastened at its ends and preferably arranged parallel to the axis 4, which form support arms 5b and 5c, at the free ends of which armrests 5d, shown schematically, can be rigidly attached. The crossbar 5a, the support arms 5b, 5c and the armrests 5d are preferably partially rigidly connected to one another or made from one piece.

The seat according to the invention is suspended from the carrier 5. The seat consists of a seat part 6 and a back part 7, which at their rear or lower ends and preferably on both sides are rotatably or pivotally connected to one another by at least a first, freely floating joint 8, which e.g. has an axis projecting through the back part 7, the two ends of which protrude into the seat part 6. The width of the seat is slightly smaller than the distance between the two support arms 5a, 5b.

The seat and back parts 6 and 7 have support elements at points spaced from the axis of rotation of the joint 8, which are movably suspended on the support 5 via positive guides. 1, for example, consists of two articulated arms 10 and 11. The articulated arm 10 is rotatable or pivotable on the one hand by a second articulation 12 with the support arm 5b or 5c and on the other hand by a support element in the form of a third articulation 13 - Or pivotally connected to the back part 7, wherein the axis of the joint 13 lies above the axis of rotation of the joint 8 (Fig. 1). The articulated arm 11 is connected on the one hand to the support arm 5b or 5c by the second articulation 12 or a further, but having the same axis of rotation, and on the other hand by a support element in the form of a fourth articulation 14 to the seat part 6, wherein the axis of rotation of the joint 14 according to FIG. 1 is arranged between the axis of rotation of the joint 8 and the free front end of the seat part 6. Preferably on each side of the seat identical joints 12, 13 and 14 and articulated arms 10 and 11 are provided. The second joints 12 are each fixed to an associated support arm 5b or 5c, that is to say immovably, so that on both sides of the seats, joint quadrilaterals consisting of joints 8, 12, 13 and 14 are formed, each joint 12 being one represents a fixed pivot around which the moving parts of the seat mechanism can move in a variety of ways. Since the quadrilaterals on both sides of the seat can be mirror images, only the quadrilateral shown in FIG. 1 and its function are described below.

In the exemplary embodiment, the joint 8 is at a distance of 200 mm from the surface of the still upholstered seat part 6 when the same is arranged horizontally and when the back part 7 is arranged vertically. The distances between the axes of rotation of the joints 12 and 13 are approximately 170 mm, the distances between the axes of rotation of the joints 12 and 14 approximately 190 mm, the distances between the axes of rotation of the joints 8 and 14 approximately 170 mm and the distances between the axes of rotation of the joints 8 and 13 approximately 150 mm. All of these distances have proven ergonomically advantageous, but can also be varied within certain limits.

In order to prevent the back part 7 from buckling when in an extreme lying position, it has a stop 15 which interacts with the seat part 6 and permits a maximum angle of 180 ° between the latter and the back part.

The possible adjustments of the seat part 6 and the back part 7 by means of the four-bar linkage are shown schematically in FIG. 2 for a large number of different sitting positions. These seating positions are possible in that the axes of the joints 13 and 14 can be moved individually or both in combination along cylindrical surfaces, the axes of which coincide with the axis of rotation of the second joint 12. The articulated arms 10 and 11 represent constrained guides that define the radii for the curved movements of the joints 13 and 14. In contrast, the joint 8 is kept freely suspended, which is why the angle of inclination of one of the parts 6, 7 can also be kept constant and only the angle of inclination of the other part 6, 7 can be changed. By locking the joints 13 and 14, the back or seat parts 7 and 6 can also be spatially fixed.

In order to give the articulated arms 10, 11 a lateral guidance and to be able to lock the various seating positions according to FIG. 2 in a simple manner, the articulated arms 10, 11 are additionally guided on the carrier 5. In the embodiment according to FIG. 1, the articulated arms 10 and 11 are rigidly connected with fastening arms 16 and 17, which are shown in FIG. 1 in a purely schematic manner. The fastening arm 16 is connected to the articulated arm 10, extends in the direction of the articulated arm 11 and is circular. The fastening arm 17 is connected to the articulated arm 11, extends in the direction of the articulated arm 10 and is designed in the form of a circular arc. In both cases, the center point of the circular arc lies on the axis of rotation of the second joint 12. If the distance between the fastening arms 16, 17 according to FIG. 1 is relatively small, both can be connected to a common clamping element 18, e.g. a clamping screw or the like, are determined or released to change the seating position, i.e. form a locking device assigned to the positive guides, since the distances of the different parts of the fastening arms 16, 17 from the clamping screw 18 do not change when producing the possible seating positions. Alternatively, each fastening arm 16, 17 could be assigned its own clamping screw 18.

In the preferred embodiment for reasons of stability and ease of manufacture, which is shown in FIGS. 3, 4 and 5, the articulated arms 10, 11 are parts of a disk 19 and 20, respectively. In FIG. 4, the joints 12, 13 are schematic and 14 and their connection points with the disks 19, 20 indicated. Each disc 19, 20 has an elongated hole in the form of an arcuate slot 21 or 22, the axis of rotation of the second joint 12 in turn running through the centers of the arcs. In addition, the radii of the arcs of the slots 21 and 22 are identical. Incidentally, both disks 19, 20 are so large that they lie against one another over a wide area in all desired seat positions that can be produced. The support arm 5b and 5c has, as shown in FIGS. 3 and 4, a guide member projecting through both slots 21, 22, which consists, for example, of a bolt 23 which loosely or fits through the support arm 5c, so that the joint 12, the bolts 23 and the disks 19 and 20 each represent positive guides for the support elements of the seat designed as joints 13, 14. The joints 8 are in turn freely suspended.

The bolt 23 has an outer head 24 which comes to rest on the outside of a lever 26 which bears against the support arm 5c. The disc 20 bears on the inside of the support arm 5c and the disc 19 bears on the inside thereof, the bolt 23 also projecting through the slots 21 and 22, respectively. At the free end of the bolt 23, a clamping member 25 is fastened, which comes to lie between the inside of the disc 19 and the seat and, together with the discs 19, 20, forms a locking device for the positive guidance. A corresponding arrangement is provided on the other support arm 5b. The clamping member 25 is e.g. a nut, which is screwed onto a threaded portion of the bolt 23, so that when the nut is tightened, the washers 19, 20 are pressed against one another and against the support arm 5c, with the result that the currently seated position is locked due to the clamping action of these parts. After loosening the clamping member 25, the disks 19, 20 can slide against one another or on the support arm 5c, which enables a change in the seating position. A particular advantage of the washers 19, 20 and slots 21, 22 is that by preselecting the length of the slots, the adjustment range of the seat can be determined because the pin 23 strikes at least one end of the slots 21, 22 in the extreme sitting positions . The slot length therefore also defines the extreme positions of the seat part 6 and the back part 7 at the same time.

For easy manufacture and locking of any sitting position by simply shifting your body weight, it has proven to be favorable, the friction between the disks 19, 20 low and the friction between the support arms 5b, 5c and the disks 19, 20 or between these and the clamping piece 25 large to choose. The easiest way to achieve this is to insert washers with correspondingly high or low coefficients of friction between the parts mentioned.

So that the seating position desired in the individual case can be changed with a simple hand lever without turning the bolt 23 or the clamping member 25, the locking device according to FIG. 3 has the two-armed lever 26 on both sides of the seat, which lever, for example, on the outside of the associated Support arms 5b, 5c pivotally mounted and arranged parallel to them. A lever arm is penetrated by a section of the bolt 23 located between the head 24 and the support arm 5b 5c. In In a central part, the lever 26 is pivotably mounted on the support arm 5b, 5c by means of a roller 27 or the like. One end of a rope 28 is attached to its other lever arm and extends between the two support arms 5b 5c or levers 26 (FIG. 3).

A spring 29, preferably designed as a leaf spring, is also arranged in the center under the cable 28 and on the crosspiece 5a, a wire rope that holds tension with a preselected force. As a result, the upper lever arms in FIG. 3 of the lever 26 and with them the heads 24 of the bolts 23 are prestressed by spring force, which results in a mutual jamming of the disks 19, 20 on the support arms 5b 5c under the influence of the clamping members 25 . In this embodiment, the clamping members 25 can therefore also be designed, for example, as snap rings or the like. The respective sitting position is thus locked by clamping. If it is desired to produce a different sitting position, the spring 29 is tensioned by means of an actuating mechanism 30 by pulling it into the position indicated by the broken line in FIG. 3. As a result, the cable 28 is relaxed and the spring force acting on the levers 26 is reduced so much that the clamping action between the disks 19, 20 and the support arms 5b, 5c is largely eliminated. After release of the actuating mechanism 30, the spring 29 returns to its largely relaxed position, so that the locking is effective again. The actuating mechanism 30 contains, for example, a Bowden cable 31, the pull cable 32 is fastened on the one hand to the spring 29 (FIG. 3) and on the other hand to an operating lever 33 which is pivotably mounted in an easy-to-grip position, for example on one of the armrests 5d (FIG. 1). In this case, the clamping force can be metered by only partially actuating the operating lever 33 such that a smaller or greater force is required to change the sitting position, as required.

According to a third embodiment of the invention (FIGS. 6 and 7), in which the same parts are provided with the same reference numerals as in FIGS. 1 to 5, the axis 4 is connected to a U-shaped support 34, which is preferably perpendicular to the axis 4 arranged transverse web 34a and two legs fastened at its ends and expediently arranged parallel to the axis 4 in the form of preferably frame-shaped side parts 34b and 34c, the transverse web 34a, the side parts 34b and 34c and the axis 4 preferably being rigidly connected to one another in part or made in one piece are. The side part 34c is designed like a half ring and has a lower, circular-arc-shaped frame part 35 which extends, for example, about a third of a circle. One end of the frame part 35 is connected to the one end of a web 36, which runs essentially perpendicular to the axis 4 and at the same time can be designed as an armrest, while the other end of the frame part 35 is connected to the other end of the web 36 via a web 37 connected is. The other side part 34b is designed accordingly. The upper region of the side parts 34b, 34c formed from the webs 36, 37 can alternatively be designed freely or can also be omitted.

The seat designed according to FIGS. 1 to 5 has support elements at locations spaced from the joints 8, which consist, for example, of pins 38a, b provided on both sides of the seat part 6 and pins 39a, b attached to both sides of the back part 7, for example consist of the ends of axles or rotatable shafts 38 or 39 which project through the seat or back part 6 or 7 and which are arranged parallel to the axis of rotation of the joint 8. The pins 38a, b each protrude into slots 40 which run in the form of a circular arc and are formed in front sections of the arcuate frame parts 35, while the pins 39a, b each project into slots 41 which run in the form of an arc of a circle and are formed in rear sections of the frame parts 35. The lower boundaries of the slots 40, 41 act as control curves for the pins 38a, b and 39a, b lying thereon and guided by them, the axes of which are arranged essentially parallel to the axis of rotation of the joint 8. The hinge 8 is in turn freely suspended, so that the pins 38a, b of the seat part 6 with the back part 7 held in the slots 40 or the pins 39a, b of the back part 7 with the seat part 6 held in the slots 41 to and fro can be. A combined movement of both the seat part and the back part 6 or 7 is also possible. The frame part 35 with its slots 40 and 41 thus constitutes a positive guide for the support elements of the seat or back part which are designed as pins 38a, b and 39a, b. The pins 38a, b and 39a, b are also expediently cylindrical and therefore in the slots 40 and 41 rotatably mounted so that they can also rotate when adjusting the seat or back part. Analogously to FIG. 2, FIG. 6 shows three different positions that the seat or back part 6 or 7 can assume, with solid, dotted or dashed lines Lines. The length of the adjustment path is predetermined by the length of the slots 40, 41.

An embodiment of the invention similar to the embodiment according to FIGS. 6 and 7 is shown in FIGS. 8 to 12 in connection with a locking device. In this case, the side parts 34b, 34c shown in FIGS. 6 and 7 are replaced by side parts 44 with an otherwise identical arrangement, which are designed in two parts and each have an outer part 45 and an inner part 46. Both side parts 44 and with them the outer and inner parts 45 or 46 are preferably semi-ring-shaped and otherwise mirror images. Each outer part 45 has an arcuate base part 47 and a guide part 48 arranged perpendicularly thereto, in which there are correspondingly shaped grooves 49a and 49b at those points where the slots 40, 41 are arranged in FIGS. 6 and 7.

The support elements shown in FIGS. 6 and 7 as simple pins 38a, b and 39a, b are designed here as gear wheels 52a, 52b, which are rotatably mounted on both sides of the seat or back part 6 and 7, respectively. The gear wheels 52a, b are designed, for example, as external toothings at the ends of shafts 53 which are rotatably mounted in the seat or back part 6 or 7 and whose ends protrude laterally therefrom. Short cylindrical guide pins 54 adjoin the gear wheels 52a, b on the outside. The length of the shafts 53 between the two side parts 44 is dimensioned such that the guide pins 54 come to lie in the grooves 49a, b. At the same time, the bottom parts 47 have a corresponding control cam in the form of an internal toothing 55a or 55b, in which the gear wheels 52a, b engage and which run along circular arcs which correspond exactly to the circular arcs along which the grooves 49a, b run. To adjust the seat part 6 or back part 7, the gear wheels 52a, b can therefore roll on the corresponding internal gears 55a, b, the shafts 53 rotating simultaneously in the seat part 6 or back part 7 and the guide pins 54 being guided in the grooves 49a, b whose ends define the ends of the possible adjustment range. To reduce the friction, it is possible to select the height of the grooves 49a, b somewhat larger than the diameter of the guide pin 54 corresponds. The guide pins 54 and grooves 49a, b also prevent unwanted disassembly of the seat and back parts. The adjustment mechanisms for the seat part 6 and the back part 7 are essentially identical.

In the embodiment according to FIGS. 8 to 12, the inner part 46, which in FIGS. 8 and 11 assumes its locking position, serves as the locking device. The inner part 46 is also preferably semi-ring-shaped and designed in the manner of an angle profile and is provided with a lateral guide part 57 and an upper part 58, each of which has an inner toothing 59a or 59b which is opposite the inner toothing 55a, b and arranged parallel thereto. The guide part 57 lies along a stepped recess provided in the guide part 48 of the outer part 45 from the outside and can be displaced radially relative to the latter.

Normally, the inner part 46 is made with the aid of at least one spring 60 or the like, which is only indicated schematically in FIGS. 8, 11 and 12 and is e.g. between the inner part 46 and the outer part 45, biased into the locking position shown in FIGS. 8 and 11, in which its internal teeth 59a, b are in engagement with the gear wheels 52a, b. In this locking position it is therefore impossible for the seat or back part 6 or 7 to be adjusted in one direction or the other. If, on the other hand, the inner part 46 is raised somewhat against the force of the spring 60, for this purpose there is sufficient free space 61 between the upper sections of the bottom or upper part 47 or 58 of the inner or outer part 46 or 45 (FIGS. 8 and 10). 12, its internal gears 59a, b are lifted off from the gear wheels 52a, b, as shown in FIG. 12, so that they can roll in one direction or the other on the internal gears 55a, b of the outer part 45, as a result of which the respective position of the seat - And / or back part 6 or 7 changed accordingly. At the same time, the spring 60 can be designed such that it prevents the inner part 46 from being pulled away laterally from the outer part 45.

The internal toothing of the inner and outer parts 46 and 45 shown in FIGS. 8 to 12 can extend over the entire length of the bottom or upper parts 47 or 58 or only over the length of the grooves 49a, b corresponding sections. It is also possible to arrange the spring 60 or any additional springs between the inner part 46 and the outer part 45 in such a way that the inner part 46 can be moved such that only the gear wheels 52a of the seat part 6 or 52b of the back part 7 are released, which enables independent adjustment of the seat and back sections while locking the other section at the same time. After all, it would be too possible to form the inner part 46 in two parts and to assign one part to the seat part 6, the other part to the back part 7. It would also be possible to omit the inner parts 46 and instead, for example, selectively block or release the rolling movements of the gear wheels 52a, b with means not shown, for example arranged in the seat part.

The ends of the shafts 53, which are rotatably mounted in the seat or back part, can be replaced by rigid axles or pins, which are provided with gear wheels rotatably mounted on them.

The embodiment according to FIGS. 8 to 12 has the particular advantage that the seat or back part 6 or 7 is positively guided at both lateral ends in such a way that the shafts 53 or the like due to the toothing cannot tilt or tilt at both ends, as would be conceivable with the positive guidance shown in FIGS. 6 and 7.

The distances of the pins 38a, b and 39a, b or of the gear wheels 52a, b in the embodiments according to FIGS. 6 to 12 from the joints 8 can be selected as for the distances between the joints 13 and 14 and the joints 8 the embodiment of FIGS. 1 to 5 is specified. The radii of the arcs, along which the slots 40, 41 or grooves 49a, b run, can, on the other hand, be dimensioned according to the length of the articulated arms 10, 11 of the embodiment according to FIGS. 1 to 5.

According to a fifth embodiment, shown in FIGS. 13 to 18, a U-shaped support 64, which is preferably produced in one piece and which consists of a transverse web 64a and two perpendicularly arranged, preferably frame-shaped side parts 64b, 64c, is on the axis 4 in accordance with the other embodiments attached. The side part 64c is semi-ring-shaped and has a lower, preferably circular-arc-shaped frame part 65 which, for example, consists of a profile bar with a rectangular, square, circular or tubular cross-section and extends, for example, over a third of a circle. One end of the frame part 65 is connected to the one end of a web 66, which runs essentially perpendicular to the axis 4 and at the same time can be designed as an armrest, while the other end of the frame part 65 is connected to the other end of the web 66 via a web 67 connected is. The other side part 64b is designed accordingly. The upper region of the side parts 64b, c formed from the webs 66, 67 can alternatively be designed freely or can also be omitted.

The seat designed according to FIGS. 1 to 5 has support elements on both sides and at locations spaced from the joints 8, which consist, for example, of guide bodies 68 provided on both sides of the seat part 6 and guide bodies 69 arranged on both sides of the back part 7. These guide bodies 68, 69 are rigidly attached to the ends of axles 70 and 71, which are rotatably mounted in the seat and back parts 6, 7, or are rotatably mounted on axles, which are rigidly mounted in the seat and back parts 6, 7, and each have a passage 68a or 69a (FIGS. 17, 18), which is penetrated by one of the frame parts 65.

The frame parts 65 are provided on their upper parts with control curves in the form of sliding surfaces 72 and on their undersides with external toothing 73a, 73b. The passages 68a, 69a are delimited on their upper sides by sliding surfaces 74 shaped in accordance with the sliding surfaces 72 (FIG. 17) and on their undersides by inner toothings 75 shaped in accordance with the external toothings 73a, 73b, the spacing of which from the sliding surfaces 74 is somewhat greater than the spacing of the External teeth 73a, b of the sliding surfaces 72. Between the frame parts 65 and the guide bodies 68, 69, springs 76, schematically indicated in FIGS. 16 and 18, are also supported, which normally, i.e. in the unloaded state of the seat, act on the guide bodies 68, 69 in such a way that their internal toothings 75 are in engagement with the external toothings 73a, b and therefore form a locking device which makes it impossible to move the guide bodies 68, 69 on the frame parts 65 (FIG 17).

If, on the other hand, the seat is loaded, for example by the weight of a person acting on the seat and / or back part 6, 7 and thus on the guide body 68 and / or 69, this results in a transverse movement of the respective guide body 68, 69 to the frame part 65 (Fig. 18). As a result, the internal toothing 75 of the respective guide body 68, 69 is lifted off the external toothing 73a, b of the associated frame part 65, whereby an unlocking takes place, so that the seat and / or back part 6, 7 can now be moved as desired by parallel displacement of the sliding surfaces 72, 74 of the frame part 65 can be moved. The frame parts 65 with their sliding surfaces 72 thus provide one hand Forced guidance for the support elements designed as guide bodies 68, 69 and, on the other hand, form a locking device with their external teeth 75. In addition, a further locking device, not shown, could be provided, so that the selected seating position can be locked even in the loaded state. However, the springs 76 and the friction conditions are preferably selected such that an adjustment of the seating position is only possible with a certain minimum effort even in the loaded state and therefore not every slight movement of the body results in an adjustment of the seating position. In addition, limiting means (not shown) are preferably provided which, as in the other embodiments, limit the possible movement stroke of the guide bodies 68, 69 on the frame parts 65 and consist, for example, of pins attached to the guide bodies 68, 69 and engaging in grooves in the frame parts 65 or vice versa.

The sixth embodiment of the invention shown in FIGS. 19 to 23 contains, according to FIGS. 1 to 5, the seat and back parts 6 and 7 connected by at least one freely floating joint 8, the articulated arms 10 and 11 by the at least one second joint 12 are connected to the support arms 5b and 5c, not shown, and the third and fourth joints 13 and 14, which act as support elements. As far as the other parts are identical to the embodiment according to FIGS. 1 to 5, they are shown in FIGS. 19 to 23 omitted for simplicity.

The sixth embodiment differs from that according to FIGS. 1 to 5 in that the seat part 6 consists of two seat part sections 6a, 6b pivotally connected by the joint 14 and the back part 7 consists of two back part sections 7a, 7b pivotally connected by the joint 13 . The joint 14 is expediently arranged approximately in the initial region of the thighs and the joint 13 approximately in the region of the lower lumbar vertebrae of a person of average size, so that the seat part section 6b supports most of the thighs and the back part section 7b supports most of the back and the parts 6a, 7a essentially form only one type of seat shell.

20 schematically shows the individual parts before they are assembled. The seat and back sections 6a, 6b, 7a and 7b have at their ends and on both sides, for example, articulated eyes 81 to 86, while the articulated arms 10, 11 are provided at their ends with joint eyes 87 to 90, for example. All of these articulated eyes are schematically indicated in FIG. 20 by large circles and connected to one another by joints, continuous axes or the like in the manner shown in FIG. 19 to form the joints 13, 14. In addition, the seat section 6b has at least one rigidly attached lever arm 91 at its end facing the seat section 6a and the seat section 6a has a rigidly attached lever arm 92 which is extended beyond the joint eyes 83, while the back section 7b accordingly has at least one end at its end facing the back section 7a rigidly attached lever arm 93 and the back section 7a is provided with at least one rigidly attached lever arm 94 projecting beyond the articulated eyes 84. The free ends of the lever arms 91 to 94 are designed as articulated eyes 91a to 94a, which are indicated in FIG. 20 as small circles. Finally, levers 95 and 96 are provided, which are provided at their ends with further articulated eyes 95a, b and 96a, b, also indicated by small circles. The pivot eyes 95a with the articulated eyes 91a, the articulated eyes 95b with the articulated eyes 94a, the articulated eyes 96a with the articulated eyes 93a and the articulated eyes 96b with the articulated eyes 92a are used for further rotation with the help of pivot pins, continuous axes or the like - or swivel joints connected so that the arrangement shown in FIG. 19 results.

Via the lever 95, the seat section 6b is thus additionally articulated to the lever arm 94 of the back section 7a and the back section 7b is articulated to the lever arm 92 of the seat section 6a. On the one hand, this has the consequence that, for example, when the articulated arm 11 or articulation 14 is held in place, a movement of the articulated arm 10 or articulation 13 not only causes the movements of the seat or back section 6a, 7a which can also be seen in FIGS. 1 and 2, but rather that in addition the levers 95, 96 bring about a relative pivoting of the seat sections 6a, 6b or the back sections 7a, 7b relative to one another about the axes of rotation of the joints 13 and 14. The same applies if the articulated arm 10 and the articulation 13 remain fixed in space and only the articulated arm 11 or the articulation 14 moves or both articulated arms 10, 11 and thus both articulations 13, 14 are moved relative to one another.

FIG. 19 shows a position in which the seat sections 6a, 6b on the one hand and the back sections 7a, 7b on the other hand each lie in the same plane. The lengths of the lever arms 91 to 94 and the lever 95, 96 are e.g. chosen so that when the angle between the seat or back section 6a, 7a is increased, the rear sides of the back section 7a, 7b form a gradually increasing obtuse angle with one another. If the articulated arm 11 or the articulation 14 is simultaneously moved in the manner shown in FIGS. 21 to 23, then in the lying position according to FIG. 23 there is the advantage that the back part 7a, 7b is not in one plane with the seat part 6a, 6b, but the seat and back sections 6a, 7a form a distinctly pronounced seat shell (FIG. 23) and the back section 7b is essentially parallel, but somewhat higher than the seat section 6b. This enables a favorable lying position in ergonomic terms. In addition, as shown in FIGS. 21 to 23, when lowering the back part 7a, 7b, simultaneous lifting of the seat part sections 6b intended for supporting the thighs can be avoided in a simple manner and without a significant shift in the center of gravity. In a particularly preferred embodiment, the seat section 6b is held in the same, preferably horizontal position in all positions of the seat (FIGS. 21 to 23), for example by rigidly fixing the joint 14 to the carrier. It is also particularly advantageous that the part 7 serving as the backrest is gradually bent backwards during the transition from the sitting position into the lying position, which is preferred for ergonomic reasons, in particular if the joint 13 is arranged approximately at the level of the lower lumbar vertebrae. A corresponding kinking of the part 6 serving as the seat surface finally leads to the fact that the seat shell formed from the sections 6a, 7a is arranged in an anatomically correct manner or is formed, in particular, during the transition to the lying position. Apart from this, such a lever mechanism can also be used to set up any other combination of sitting or lying positions that is considered appropriate.

The lever mechanism described with reference to FIGS. 19 to 23 can also be provided accordingly in the embodiments according to FIGS. 6 to 18, since it is unimportant for their application in which way the support elements formed by the joints 13, 14 or the like are worn or supported. In addition, it is possible to design only the seat or back part in two parts and to couple one of the two parts to the then one-piece back or seat part via a lever mechanism.

The invention is not restricted to the described embodiments, which can be modified in many ways. This applies, for example, to the carrier 5, which could also be fastened to a rigidly mounted frame 1 that cannot be moved on rollers or wheels 2, but also with regard to the shapes for the carriers, frame parts, positive guides, supporting elements, locking devices described with reference to the drawings and the like, which can be adapted in particular to the given formal requirements, even if the embodiment according to FIGS. 13 to 18 is currently considered the cheapest solution because it requires few parts, has a simple construction and an automatic locking and unlocking of the Seat and back parts made possible solely by shifting body weight, so that no additional controls need to be provided for this. In particular, it is possible to combine the individual parts and assemblies described with reference to the six exemplary embodiments in a variety of ways. It would also be conceivable to mount the various slots, control cams or the like. Of the positive guides on the seat and back parts and the associated bolts, pins, gears or the like on the carrier.

1 and 23, the seat and back parts 6 and 7 of the described seat consist of plate-shaped components with rectangular or square cross sections, which are connected to one another by the first joints 8. Alternatively, both parts can also be designed merely as tubular frames or the like, which serve to hold a continuous, flexible seat and backrest element, the surface of which is shaped in accordance with the ergonomically desired conditions. Any upholstery or the like has been omitted from the drawing to simplify the illustration. Since the joints are freely suspended, they can alternatively be replaced by strips of material or the like made of a flexible material.

The radii of the arcs, along which the various support elements are positively guided, can be the same size according to FIGS. 6 to 18 or different sizes according to FIGS. 1 to 5 and 19 to 23. In the embodiments according to FIGS. 6 to 18, this can be realized, for example in accordance with FIG. 24, by providing side parts 101, the two have frame parts 103a and 103b connected by a step 102, both of which run along circular arcs with different radii and are used, for example, to guide the guide bodies 68, 69 according to FIGS. 13 to 18. Similarly, side parts could be provided which are designed according to FIGS. 6 to 12 and whose slots 40, 41 or internal toothings 55a, b run along circular arcs with different radii. It would also be possible, for example, to provide the trunnions 39a, b corresponding to FIGS. 6 and 7 or the gearwheels 52b according to FIGS. 8 to 12 as support elements for the back part 7, so that its pivot axis is arranged in the immediate vicinity of the movement paths defined by the positive guidance 13 to 18, the pivoting axes (axes 70) for the seat part 6 being at a relatively large distance from the path defined by the positive guidance (eg sliding surface 72) can. Such an arrangement is indicated schematically in FIG. 25 with reference to a frame part 105, to which a support element 106 supporting the back part with a pivot axis arranged essentially in the axis of the frame part and a support element 107 supporting the seat part with a pivot axis 108 are associated, which are at a relatively large distance can have from the frame part axis. Similar relationships could also be created, for example, by starting from the embodiment according to FIGS. 6 and 7 and providing cranked or offset pins 38a, b or 39a, b. Finally, FIG. 26 shows an exemplary embodiment in which tracks 111 and 112 defined by the positive guides for support elements 109 and 110 are not arcuate, but have a different course. Apart from this, it is possible, for example, to give the slots 40, 41 according to FIGS. 6 and 7 a different length or to select the lengths for the positive guides provided in the other embodiments by corresponding limiting means, so that different adjustment ranges for the support elements of the Seat or back parts result.

The embodiments according to FIGS. 8 to 16 are further not limited to the toothings 55a, b and 59a, b described on the one hand and 73a, b and 75 on the other hand. Rather, these can also be replaced by braking surfaces with a sufficiently high frictional resistance, which are pressed against one another when the springs 60, 76 become effective and then prevent further adjustments of the seat or back parts.

In the embodiments according to FIGS. 1 to 5 and 19 to 23, it is not absolutely necessary for the articulated arms 10, 11 to be rotatable or pivotable about the same axis represented by the articulation 12. It would also be possible to mount the articulated arms 10, 11 rotatable or pivotable about different axes. Correspondingly, the center points of the movement paths formed by the control curves of the embodiments according to FIGS. 6 to 18, if they are circular paths, can lie on the same axis or also on different axes. However, a close proximity or collapse of these two axes and the arrangement of both axes in the extension of the axis 4 is preferred because it has the advantage that the user's center of gravity is essentially unchanged in the axis 4 in all intended sitting and lying positions or their imaginary extension remains arranged, whereby a high level of stability of the office chair shown is achieved. The same applies during the body weight shifts required to change the sitting or lying position. It is also advantageous that the backrest always rests on the back of the user, any position can be locked and the center of gravity can level off automatically via the center column (axis 4) of the office chair.

The embodiment described with reference to FIGS. 19 to 23 shows only the schematic structure of the lever mechanism, the lengths of the levers 95, 96 and lever arms 91 to 94 and the angles between the sections 6a, 6b or 7a, 7b and the lever arms 91 to 94 are only simplified and shown as examples. There are actually numerous possible variations for these lengths and angles, and they are preferably carefully coordinated with one another in order to follow or take account of the natural movement sequence of the human body. Since the levers 95 and 96 are predominantly subjected to tension, it is possible not to manufacture them from rigid, but from flexible materials, for example steel cables. In addition, it is not necessary to coaxially arrange the pivot axes of the joints 13 and 14 on the one hand and the joints 81, 82 and 85.86 on the other hand. Rather, it would also be conceivable to arrange the joints 13, 14 separately and at a distance from the joints 81, 82 and 85, 86, so that the joints 13 and 85, 86 on the one hand and 14 and 81, 82 on the other hand about spaced axes are pivotable.

• 1) Der Neigungswinkel b des Rückenteils kann verändert werden, ohne daß gleichzeitig der Neigungswinkel a des Sitzteils 6 verändert werden muß. Dies zeigt Fig. 2 anhand der beiden Positionen, die durch Linien 122 und 124 angedeutet sind und unterschiedliche Neigungswinkel b für das Rückenteil bei jeweils horizontalem Sitzteil bieten.
• 2) Entsprechend kann der Neigungswinkel a des Sitzteils verändert werden, ohne daß gleichzeitig der Neigungswinkel b des Rückenteils verändert werden muß. Dies ist in Fig. 2 nicht gesondert dargestellt, ergibt sich aber folgerichtig aus der Analogie der Zwangsführungen für das Sitz- und Rückenteil.
• 3) Der Öffnungswinkel c wird bei der Verstellung des Rücken- oder Sitzteils nach 1) und 2) automatisch ebenfalls verändert. Zusätzlich ist es allerdings möglich, diesen Öffnungswinkel c auch dadurch zu verstellen, daß sowohl der Neigungswinkel a des Sitzteils als auch der Neigungswinkel b des Rückenteils verändert wird. Dies ist in Fig. 2 beispielsweise aus den Positionen ersichtlich, die durch die Linien 121, 124 und 125 angedeutet sind.
• 4) Schließlich kann die aus Sitz- und Rückenteil gebildete Kombination vorzugsweise auch als Ganzes, d.h. bei konstant bleibendem Öffnungswinkel c verschwenkt werden, wie in Fig. 2 beispielsweise durch Linien 125 und 126 für die extreme Liegeposition (Öffnungswinkel c = 180°) dargestellt ist. Entsprechendes ergibt sich aus Fig. 6 für die beiden dort dargestellten Sitzpositionen.

The seats described with reference to FIGS. 1 to 18 and 24 to 26 and their positive guides are constructed according to the invention in such a way that they can at least perform the functions described below with reference to FIG. 2. Essential for this are on the one hand the inclination angles a and b of the seat or back part 6 and 7, which are each related to the horizontal when the entire seat is in its position of use on a horizontal, flat surface, and on the other hand an opening angle c that is enclosed by the seat and back parts 6 and 7. The angles of inclination a and b define the absolute position of the seat and back parts, while the opening angle c defines their relative position to one another. 2 shows six positions of the seat, which are characterized by lines 121-126.

• 1) The angle of inclination b of the back part can be changed without simultaneously changing the angle of inclination a of the seat part 6. This is shown in FIG. 2 on the basis of the two positions, which are indicated by lines 122 and 124 and offer different inclination angles b for the back part with a horizontal seat part in each case.
• 2) Accordingly, the angle of inclination a of the seat part can be changed without simultaneously changing the angle of inclination b of the back part. This is not shown separately in FIG. 2, but results logically from the analogy of the positive guides for the seat and back part.
• 3) The opening angle c is also automatically changed when the back or seat part is adjusted according to 1) and 2). In addition, however, it is also possible to adjust this opening angle c by changing both the angle of inclination a of the seat part and the angle of inclination b of the back part. This can be seen in FIG. 2, for example, from the positions indicated by lines 121, 124 and 125.
• 4) Finally, the combination formed from the seat and back part can preferably also be pivoted as a whole, ie with the opening angle c remaining constant, as shown in FIG. 2 for example by lines 125 and 126 for the extreme lying position (opening angle c = 180 °) . The corresponding results from FIG. 6 for the two sitting positions shown there.

All of these diverse settings can be made continuously and steplessly by simply shifting the weight within those limits which are determined by the positive guides themselves or the tracks predetermined by them and, if appropriate, stops provided at the ends or the like. Therefore, the user of the seat according to the invention can set a plurality of sitting or lying positions between an extreme sitting position ( c ≈ 90 °) and an extreme lying position ( c ≈ 180 °) and lock them if necessary using the described locking devices.

Another significant advantage of the invention is that the center of gravity of the seat always adjusts itself automatically above the pipe 3 or its axis 4 due to the gravity of the user, regardless of which special sitting or lying position is selected. This is in particular a consequence of the fact that the positive guides for the seat part 6 are arranged essentially on one side and the positive guides for the back part 7 are arranged essentially on the other side of a plane passing through the axis 4 and parallel to the axis of rotation of the joint 8 runs. This applies in particular if the axis of the second joint 12 or the axes corresponding to this axis intersect the axis 4 or are arranged at a short distance from it. This ensures an extremely high level of stability for the seat.

Furthermore, it is particularly advantageous that the seat automatically adapts to the respective body weight of the user and that there are no forces working against the body weight, such as spring forces or the like. Feathers or the like would have the disadvantageous consequence that the body of the user constantly works against a diffuse spring force and the spring force would have to be made adjustable with a great deal of design effort in order to be able to adapt it to the respective weight of the user.

For the use of the seat according to the invention, it is also advantageous that the contact pressure of the back part is essentially generated by the body weight of the user, since it is dependent on the distribution of the weight of the user in the position assumed in each case. For this reason too, no additional forces, in particular springs or the like, are therefore required to pretension the back part in the direction of the back of the user.

Finally, despite the advantages mentioned, the user is firmly and securely held in any seat or lying position by the combination of seat and back parts, since these do not spring back and no other forces occur apart from natural gravity. Due to the existing frictional forces, the seat is stabilized in such a way that the respective sitting position can be maintained permanently even without locking the seat or back part.

• 1) In der aus Fig. 21 ersichtlichen, als äußerste Sitzposition angenommenen Stellung ist der hintere Sitzteilabschnitt 6a gegenüber dem anderen Sitzteilabschnitt 6b leicht nach oben gewinkelt, so daß sich ein stumpfer Öffnungswinkel d von etwas weniger als 180° ergibt. Dagegen beträgt der Öffnungswinkel e etwas mehr als 180°, was einer bequemen Position beim aufrechten Sitzen entspricht.
• 2) In der aus Fig. 23 ersichtlichen, als äußerste Liegeposition angenommenen Stellung liegen die Sitz- und Rückenteilabschnitte 6b und 7b etwa parallel, wobei der Rückenteilabschnitt 7b in einer etwas höheren Ebene angeordnet ist, während die Sitzteilabschnitte 6a und 6b einen überstumpfen Öffnungswinkel d von etwas mehr als 180° und die Rückenteilabschnitte 7a und 7b einen überstumpfen Öffnungswinkel f bilden, der ebenfalls größer als 180°, aber deutlich kleiner als 270° ist. Die Sitz- und Rückenteilabschnitte 6a und 7a bilden dagegen wie in der extremen Sitzposition nach Fig. 23 einen stumpfen Öffnungswinkel e, der zwar größer als in Fig. 21, aber noch deutlich kleiner als 180° ist.
• 3) In dem Übergangsbereich von der extremen Sitzposition nach Fig. 21 in die extreme Liegeposition nach Fig. 23 werden sämtliche Öffnungswinkel d, e und f allmählich ständig größer, so daß sich die beispielsweise aus Fig. 22 ersichtliche Zwischenstellung einstellen läßt. Alle Zwischenstellungen sind dabei stufenlos und kontinuierlich herstellbar.

The lever mechanism shown in FIGS. 19 to 23 is constructed according to the invention in such a way that it can at least perform the functions described below with reference to FIGS. 21 to 23. Essential for this are the opening angle d between the two seat sections 6a and 6b, the opening angle e between the two seat and back sections 6a and 7a connected by the joint 8 and the opening angle f between the two back sections 7a and 7b, these angles in the out 22 can be seen from the top and front sides of the seat and back sections, respectively.

• 1) In the position shown in FIG. 21, assumed to be the outermost seating position, the rear seat section 6a is angled slightly upward relative to the other seat section 6b, so that an obtuse opening angle d of slightly less than 180 ° results. In contrast, the opening angle e is slightly more than 180 °, which corresponds to a comfortable position when sitting upright.
• 2) In the position shown in FIG. 23, assumed as the outermost lying position, the seat and back sections 6b and 7b lie approximately parallel, the back section 7b being arranged in a somewhat higher plane, while the seat sections 6a and 6b have an obtuse opening angle d of a little more than 180 ° and the back sections 7a and 7b form an obtuse opening angle f , which is also larger than 180 °, but significantly smaller than 270 °. Form the seat and back sections 6a and 7a on the other hand, as in the extreme sitting position according to FIG. 23, an obtuse opening angle e , which, although larger than in FIG. 21, is still significantly smaller than 180 °.
• 3) In the transition area from the extreme sitting position according to FIG. 21 into the extreme lying position according to FIG. 23, all opening angles d , e and f gradually become larger, so that the intermediate position shown for example in FIG. 22 can be adjusted. All intermediate positions are continuously and continuously producible.

The mutually dependent opening angles to be selected in the different positions depend, in particular, on the particular application of the seat and are to be determined in such a way that all possible sitting or lying positions provide an ergonomically favorable body position. The same applies to the relative change in the opening angles d , e and f to one another during the transition from the position shown in FIG. 21 to the position shown in FIG. 23. It has also proven to be advantageous to mount the seat section 6b stationary on the carrier and to arrange it essentially horizontally. When assembling the seat on the carrier in the sense of FIGS. 1-18 and 24-26, the always horizontal position of the seat portion 6b can also be brought about without fixing it to the carrier in that the seat during the transition from the extreme sitting position to the extreme lying position is guided in the constrained guides so that the angle of inclination of the seat portion 6b does not change relative to the horizontal.

Corresponding conditions for the above-described inclination and opening angles a to f are to be provided if the seat and back parts 6 and 7 or the seat and back part sections 6a, 6b, 7a and 7b do not have flat surfaces, as shown, but ergonomically have shaped surfaces or surfaces provided with appropriate padding.

Claims (14)

1. Seat for an office chair or the like with a seat part and a back part (6, 7) displaceable in particular by body displacement, and with a carrier (5, 34, 64), the seat part (6) and the back part (7) being pivotally interconnected at ends facing one another by at least one first free-floating joint (8) containing a first axis of rotation, and the seat part (6) being pivotally suspended and guided on the carrier (5, 34, 54) at a point spaced away from the axis of rotation by means of at least one system of positive guidance, and being mounted to be movable along a path determined by the system of positive guidance, characterised in that the back part (7) is pivotally suspended and guided at a point spaced away from the axis of rotation, and is movably guided along a path determined by the further system of positive guidance, so that the aperture angle (c) between the seat part (6) and the back part (7) is alterable both by simultaneous alteration in the angle of inclination of the seat and back part, and also by alteration in the angle of inclination only of the seat part (6) or only of the back part (7).
2. Seat according to claim 1, characterised in that the positive guidance systems are so designed that the combination of seat part and back part is pivotable as a whole at a constant aperture angle (c).
3. Seat according to claim 1, characterised in that the paths defined by the positive guidance systems comprise circular paths with centre points which lie on the carrier axis (4),or are disposed at a short distance from the carrier axis (4).
4. Seat according to claim 1, characterised in that the positive guidance systems comprise at least two articulated arms (10, 11), each pivotally connected by a respective second joint (12) to the carrier (5), and the seat and back part (6, 7) each have at least one support member comprising a third or fourth joint (13, 14) pivotally connecting the seat or back part (6, 7) to one of the articulated arms (10, 11).
5. Seat according to claim 4, characterised in that the articulated arms (10, 11) respectively form part of large-surface discs (19, 20) abutting on one another, each disc (19, 20) having a slot (21, 22) extending along an arc through the centre point of which the axis of rotation of the second joint (12) passes, and in that the slot (21, 22) is penetrated by a guide member secured on the carrier (5).
6. Seat according to claim 4 or 5, characterised in that the second joint (12) is secured on the carrier (5) so as to be immobile.
7. Seat according to claim 1, characterised in that the positive guidance systems comprise at least two control cams on at least one lateral portion (34b, 34c; 44; 64b, 64c) secured to the carrier (34, 64), and the seat part (6) and the back part (7) each have at least one support member which is positively guided on one of the control cams.
8. Seat according to claim 7, characterised in that there is attached to the carrier (34) and to both sides of the seat or back part (6, 7) a respective lateral portion (44) with at least one respective control cam in the form of an internal toothing (55a, 55b), and the support members comprise toothed wheels (52a, 52b) guided on the internal toothings (55a, 55b), and provided on the seat or back part (6,7).
9. Seat according to claim 8, characterised in that the lateral portions (44) comprise a respective outer portion (45) having the inner toothings (55a, 55b), and an inner portion (46) designed as a locking device for the support members, and the inner portions (46) have inner toothings (59a, 59b) which may be brought into engagement with the toothed wheels (52a, 52b).
10. Seat according to claim 9, characterised in that the inner portions (46) are urged by spring force into a locked position in which the inner toothings (59a, b) are in engagement with the toothed wheels (52a, 52b).
11. Seat according to claim 7, characterised in that there is attached to the carrier (64) and to both sides of the seat or back part (6, 7) a respective lateral portion (64b, 64c) with at least one respective control cam designed as a frame portion (65), and the support members comprise guide members (68, 69) displaceably mounted on the frame portions (65) and provided with passages (68a, 68b) through which the frame portions (65) penetrate, said passages (68a, 68b) being defined on at least one side by sliding surfaces (74) operating in conjunction with the frame portions (65).
12. Seat according to claim 11, characterised in that external toothings (73a, 73b) provided on the undersides of the frame portions (65), and inner toothings (75) which may be brought into engagement with the former, form, on walls of the guide members (68, 69) associated with said toothings, and defining the walls of the passages (68a, 68b), a locking device for the support members.
13. Seat according to claim 12, characterised in that, when the seat or back part (6, 7) are in the unloaded condition, the external and internal toothings (73a, b; 75) are held in engagement by spring force, and may be disengaged by loading the seat or back part (6, 7).
14. Seat according to claim 1, characterised in that the seat part (6) comprises two pivotally interconnected seat part sections (6a, 6b), and the back part (7) comprises two pivotally interconnected back part sections (7a, 7b), one seat part section (6a) being pivotally connected to one back part section (7a) by the joint (8), and in addition the seat part sections (6a, 6b) and the back part sections (7a, 7b) are articulated to one another by a lever mechanism (91-96) in such a way that, upon transition from one extreme seated position to an extreme lying position, the aperture angle (d,e,f) between the two pivotally interconnected seat and back part sections (6a, 7a) and between the two back part sections (7a, 7b) respectively increases gradually, in a way determined by the lever mechanism.

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