1. Field of the Invention
The invention relates to a chair, in particular an office chair.
2. Background Art
Various office chairs are known. The most simple of them comprise a seat being in a fixed location relative to the chair column. More sophisticated office chairs comprise means for adjusting the inclination of the seat.
It is an object of the invention to provide a novel office chair better meeting the physiological needs of the users.
This object is attained in a chair, in particular an office chair, comprising a pedestal; a seat support supported thereon; a seat plate supported on said seat support; and a backrest secured on said seat support.Said seat support comprises a rear supporting and guiding unit facing said backrest on which said seat plate is supported and on which said seat plate is guided obliquely relative to the horizontal line against at least one spring element. Said seat support further comprises a front supporting and guiding unit on which said seat plate is supported, and on which said seat plate is displaceably guided.
The main characteristic is to provide a seat which is longitudinally displaceable against a spring force.
Other advantageous configurations of the invention will become apparent from the sub-claims.
Additional advantages and details of the invention will become apparent from the description below of an example embodiment with reference to the drawings.
A chair 1, in particular an office chair, as schematically shown in
Now, the structure of the seat support 5 and the seat plate 6 is described in more detail with reference to
The seat plate 6 is supported on the front seat support element 12 via a front supporting and guiding unit 32. On the upper front end of the support arm 17, a support tube 33 extending horizontally outwards on both sides is secured which has a central axis 34 extending horizontally and parallel to the pivot axis 13 and the axis of the joint 30. The support tube is centrally arranged beneath the seat plate 6 and extends along approximately three quarters of the width of the seat plate 6. In the region of its two outer ends, the support tube 33 comprises annular cylindrical portions 35 on which a bearing sleeve 36 is pivotable around the axis 34. The two bearing sleeves 36 comprise on their respective upper sides a pin 37 having a radially projecting head 38 wherein the pin 37 is guided in an associated oblong hole 39 in the seat plate 6, i.e. in an oblong hole guidance. The oblong hole 39 comprises at its end towards the direction 18 a key-hole opening 40 through which the head 38 can be inserted for assembling or disassembling the seat plate 6. The width of the head 38 is larger than the width of the oblong hole 39 so that the seat plate 6 is guided displaceably along the direction 18 relative to the bearing sleeve 36, although it cannot be lifted as long as the head 38 is not located in the region of the keyhole opening 40. Parallel to the oblong hole 39, sliding rails 41 made of plastic material as the seat plate 6 and projecting downwards on both sides are provided which are supported on a sliding and supporting plate 42 extending parallel to them which is connected with the sleeve 36 and supported by it. The plate 42 projects in the direction 18 and opposite to it beyond the sleeve 36 and supports the seat plate 6 so that even in the case of a heavy user of the chair 1, bending of the front portion of the seat plate 6 is prevented. Just as the seat plate in this region, the plate 42 is slightly curved upwards, i.e. convex relative to the axis 34.
The seat plate 6 consists of a front seat plate element 43 which is supported against the front supporting and guiding unit, and a rear seat plate element 44 which is supported via a rear supporting and guiding unit 45 against the rear seat support element 14. The seat plate elements 43 and 44 are connected with one another by a joint 46. The joint 46 is a film hinge. The elements 43 and 44 and the joint 46 are integrally formed of plastic material. The front element 43 is curved upwards as mentioned before. The rear element 44 extends evenly. Along its circumference, the seat plate 6 is surrounded, when viewed from the top, by a substantially rectangular, bead-shaped edge 47 which comprises at its inner side a circumferential groove 48.
The rear supporting and guiding unit 45 comprises drum-shaped rollers 49 which are turnably borne in respective bearing recesses 50 provided on the bottom side of the seat plate element 44. Two rollers 49 respectively are arranged one behind the other which are supported on one sliding surface 27 respectively on the two arms 24 to improve the sliding of the seat plate 6 on the sliding surfaces 27. Between the arms 24, two guiding pins 51 extending parallel to the arms 24 are secured on the transverse support 22. To this end, the transverse support 22 comprises bores 52 through which a tapered portion 53 extends which is welded to the transverse support 22. On the bottom side of the rear seat plate element 44, two bearing blocks 54 are mounted which are slidably guided on the guiding pins 51. The guiding pins 51 comprise at their end sides a radially projecting screw 55 screwed into them to prevent the bearing block 54 from sliding off the guiding pin 51. Between the bearing block 54 and an abutment arranged in the region of the transverse support 22 and surrounding the guiding pin 54, a spring element in the form of two spiral springs 57 is provided between which a sleeve 58 is arranged. The sleeve 58 prevents that when the spiral springs 57 are compressed, a portion of the spiral spring abrades the guiding pin 51 causing noise and scratching it. Several small spiral springs 57 arranged one behind the other and led through a sleeve 58 are preferred instead of a single larger spiral spring although it is possible of course to use a single spiral spring on the guiding pin 51. The inclination angle a of the guiding pins 51 relative to the horizontal line B corresponds with the inclination angle a of the sliding surfaces 27 relative to the horizontal line B.
Now the functioning of the chair one is described for the case that the position of the backrest is fixed. When a person sits down on the seat 7 and thus on the seat plate 6, a force is exerted from above onto the rear seat plate element 44. Accordingly, the element 44 is displaced downwards on the slanting plane formed by the sliding surfaces 27 in the left part of
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Number | Date | Country | |
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