BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a side view of a seating furniture item according to the invention, with an upright backrest position;
FIG. 2 shows a side view of the seating furniture item of FIG. 1, with a lowered backrest position;
FIG. 3 shows a longitudinal section through the seating furniture item of FIG. 1;
FIG. 4 shows a side view of the seating furniture item, corresponding to FIG. 1, with a lowered front edge of the seat.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The drawings show in the various figures respectively an office chair 20 with a seat 21 and a backrest 22. As FIG. 1 shows, the office chair 20 has a chair column 23 at the lower end of which an X-base with runners can be arranged, which is not illustrated here. A base support 4 is fastened to the upper end of the chair column 23. A backrest support 3 is articulatedly mounted on this base support 4. The seat 21 rests on a seat support 1 which is articulately connected with the backrest support 3 via two levers 7 and 6.
The base support 4 and the lever 7 respectively have a toothing 4.1 and 7.1 which engage into each other. The toothings 4.1 and 7.1 lie respectively on circular arcs, so that the lever 7 can roll with its toothing 4.1 on the toothing 4.1 of the base support 4 like the cogwheel of a planetary gear, when it is swivelled. The lever 7 and therewith the entire synchronous mechanism for the seat 21 and the backrest 22, consisting of the backrest support 3, the seat support 1 and the two levers 6, 7, is consequently positively guided via the toothings 4.1 and 7.1.
FIG. 1 shows the chair 20 with an upright position of the backrest 22. The lever 7 is in its foremost swivel position. In this position, it is pre-stressed by a spring element 8. Its articulation point 9 on the lever 7 is adjustable in accordance with the physical weight of the user of the chair. To do this, the lever 7 has a second toothing 7.2, along which the articulation point 9, which is provided with a small cogwheel, can be moved up and down.
The further up the articulation point 9 is situated, the more strongly the spring element 8 is pre-stressed, i.e. the force is all the greater which is required to lower the backrest 22 toward the rear. For lighter persons, it is therefore expedient to move the articulation point 9 downwards with respect to the position shown in FIG. 1. In order that the position of the articulation point 9, once it has been selected, no longer moves with respect to the lever 7, when the lever 7 is swivelled by lowering of the backrest 22, a clamping lever 5 with a connecting link guide 5.1 is provided.
The clamping lever 5 likewise has a toothing, into which the cogwheel of the articulation point 9 engages. A pin or suchlike of the backrest support 3 projects into the connecting link guide 5.1. The lever 5 is thereby co-swivelled parallel to the lever 7 when the backrest 22 is lowered, and clamps the articulation point 9 securely in its position.
FIG. 2 now shows the chair 20 of FIG. 1 with the backrest 22 lowered toward the rear. The levers 6,7 and the clamping lever 5 have been swivelled into their most extreme right position. At the same time as the backrest 22, the seat 21 has also lowered itself downwards in its rear region. Through the synchronous mechanism according to the invention and the arrangement of all the rotation points of the levers 6,7 beneath the rear half of the seat 21, the rear edge is the seat 21 thereby always remains closely adjacent to the backrest 22, so that on lowering of the backrest and of the seat, a displacement of the clothing of the chair user can not take place and his back also always remains well supported in the region of the lumbar vertebrae.
FIG. 3 shows in a sectional view of the chair 20 a possibility for arresting the position of seat 21 and backrest 22. To do this, a detent slider 12 is arranged on the backrest support 3, said detent slider being able to be brought into engagement with the toothing 4.1 of the base support 4 and thereby blocking the further movement of the backrest support 3.
Finally, in FIG. 4, it is shown how the front edge of the seat 21 can be lowered or raised along the direction of the double arrow 24. To do this, a wedge slider 10 which has a toothing 10.1 is arranged on the seat support 1. A cogwheel arranged on an operating lever 11 is in engagement with this toothing 10.1
When the operating lever 11 is swivelled toward the rear along the double arrow 25, the front edge of the seat 21 is lowered, as is shown in FIG. 4. On the other hand, FIG. 1 shows the operating lever 11 in its front swivel position. The front edge of the seat 21 is now raised compared with the position in FIG. 4. In this way, the chair 20 can be adapted in a simple manner to persons having lower legs of different length.
It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the type described above.
While the invention has been illustrated and described as embodied in a seating furniture item, in particular office chair, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.
Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, be applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.
Patent Application
20080084102
