Chair, especially an office chair

Abstract

The invention relates to a chair, especially an office chair, having a seat part and a downward-slanting guide track for furnishing a combined downward and rearward motion or a combined upward and forward motion for the seat part. The seat part accordingly slides along a predetermined guide track, in many cases in cushioned fashion, to the rear and downward. To improve the ergonomics of such a chair, a swiveling device with an at least horizontal pivot shaft can be provided for pivotably disposing the seat part; the swiveling device is disposed between the seat part and the guide track, and the swiveling device is disposed so as to be movable together with the seat part along the guide track. As a result, a combined motion of the seat part can be generated, which is composed of the cooperation of the predetermined guide track and the swiveling motion about the pivot shaft of the swiveling device.

Description

[0001] The present invention relates to a chair, especially an office chair, having a seat part and a downward-slanting guide track for furnishing a combined downward and rearward motion or a combined upward and forward motion for the seat part.

[0002] One such chair is known for instance from German Patent Disclosure DE 199 00 454 A1. There, the seat element, embodied as a rigid seating shell, is disposed, on its front seat face end, on a seat holder that is guided displaceably in a guide element on the upper end region of the base part. The seat holder accordingly moves along a guide track in the guide element. The rigid seating shell is moved in a combined motion both downward and rearward by the user of the chair as he takes a seat on the chair. This motion takes place counter to the spring action of an especially designed spring device. In this reference, a spring device is described whose increase in spring force decreases beyond a certain inward yielding. The guide element slants downward and is embodied as curved convexly in the direction of the seat surface. The displacement therefore takes place essentially along a circular path. As a result, not only does the seat surface move downward and rearward, but the backrest also follows this course of motion. By using an elastic seating shell, an additional inclination of the backrest can also be accomplished, because of the greater lever forces engaging it.

[0003] Another chair of this generic type is known from German Patent Disclosure DE 4331987 A1. Its seat element is pivotable in a circular arc to the rear and downward about a pivot shaft located approximately in the ankle of a person sitting on the chair. To that end, a circularly curved guide element is used, which is secured to a base frame. The seat holder is guided slidingly in this frame, so that it can dip into the guide element counter to the force of a compression spring, in accordance with the swiveling motion of the seat element.

[0004] Also known from the prior art, however, are chair constructions in which in addition to a swiveling or tilting motion of the seating surface, a force-coupled, boosted tilting motion of the backrest occurs. From European Patent Disclosure EP 0645976 B1, for instance, a four-bar coupling gear for generating such a motion is known. However, this chair design does not make use of a downward-slanting guide track, although that kind of guide track offers better possibilities of a stable embodiment.

[0005] A disadvantage of the chairs of the generic types above is that the guide system of DE 4331987 A1, for instance, is relatively tall, and upon small rearward motions a relatively large downward motion takes place. It is true that a shallower variant construction is known from DE 199 00 454 A1. However, this variant is in need of improvement in terms of the ergonomics of the chair.

[0006] It is therefore the object of the present invention to furnish a chair of the type defined at the outset that makes an ergonomic and structurally simple embodiment possible.

[0007] According to the invention, this object is attained in that a swiveling device with an at least horizontal swivel shaft is provided for pivotably disposing the seat part, and the swiveling device together with the seat part is disposed as movable along the guide track. Besides the motions along the guide track, it is accordingly additionally possible for the seat part to be pivoted about the pivot shaft of the swiveling device. As a result, one additional motion component can be furnished. As an example, it can be stated that the seat part can incline downward much faster than is possible by means of the guide track alone, in terms of its shape. However, this embodiment also makes still other motion courses possible. Hence, the motion of the seat part is dependent not only on the slanting guide track; the possibility also exists of swiveling about the pivot shaft of the swiveling device. To that end, the swiveling device makes the connection between the guide track and the seat part.

[0008] The displacement or movement of the swiveling device along the guide track is a primary motion that the seat part executes, rather than a compensation motion to prevent stresses or the like. Therefore preferably the maximum displacement travel of the swiveling device along the guide track is greater than 30 mm, preferably 60 mm. In a particular embodiment, it amounts to between 120 and 130 mm. The combined downward and rearward motion should accordingly lead to a perceptible movement of the seat part.

[0009] It can furthermore be provided that the maximum swiveling angle about the pivot shaft of the swiveling device is greater than 5°, preferably 10°. In a particular exemplary embodiment, it is between 12° and 15°. Once again, this is meant to make it clear that courses of motion that are perceptible to the chair user are involved. Particularly in combination with the above-defined movement travel, an optimized combination seat part motion can thus be achieved.

[0010] For reasons of wear, the guide track is embodied as a sliding or rolling track, so that even severely stressed office chairs can have appropriate service lives. In that case, the seat part can be displaced along this sliding or rolling track.

[0011] In one embodiment, a coupling gear can be provided, which force-couples the displacement motion along the guide track and the swiveling motion about the pivot shaft of the swiveling device. Accordingly, both courses of motion are directly dependent on one another and cannot be executed individually. Specified movement travel distances along the guide track accordingly lead to precisely defined swiveling angles about the pivot shaft. These motion parameters can be adapted to one another for optimal ergonomic designs. Coupling gears per se are quite well known in the prior art, so that it can be left to one skilled in the art, by a choice of the appropriate parameters, to bring about the desired courses of motion.

[0012] Preferably, the coupling gear can be embodied in such a way that in a downward and rearward motion of the seat part, a swiveling motion about the pivot shaft of the swiveling device can be effected, to reinforce the downward motion of a rear seat part region. Hence the seat part tilts backward faster than specified by the direction of motion of the guide track; therefore even shallow guide tracks, in cooperation with the swiveling device, lead to ergonomically favorable courses of motion.

[0013] This effect can be reinforced, particularly in a variant, in that the pivot shaft of the swiveling device is disposed on a front seat part region. As a result of this provision, the swiveling motion of the seat part about the pivot shaft is especially pronounced.

[0014] The coupling gear can include a coupling element, which on the one hand is disposed pivotably about a basic swiveling point with a horizontal pivot shaft spaced apart from the pivot shaft of the swiveling device, and on the other hand is disposed spaced apart from the basic swiveling point via a pivotable connection with a horizontal pivot shaft, with the seat part also spaced apart from the pivot shaft of the swiveling device. The spacing of the basic swiveling point from the pivot shaft of the swiveling device and the spacing of the basic swiveling point from the pivotable connection, as well as the spacing of the pivotable connection from the pivot shaft of the swiveling device, can all be adjusted in accordance with the desired given conditions. Preferably, ergonomically favorable courses of motion are specified by the coupling element. The term coupling element is understood to mean all the individual elements and component groups that reinforce a motion of this kind on the order of a coupling gear. For good force distribution, it is accordingly also possible for split, symmetrical arrangements (on the left and right sides of the chair) to be provided, which are understood to be a coupling element in the sense of claim 8.

[0015] Favorably, the guide track and the basic swiveling point for the coupling element can be disposed stationary relative to one another. These parts can then preferably absorb the full support forces at fixedly defined points, while the swiveling device and the pivot point move along predetermined paths.

[0016] An embodiment in which the coupling element is embodied as a component part of a backrest is especially favorable. As a result, the backrest is included in the entire course of motion. Boosting ratios between the inclination of the seat part and the backrest can therefore also be simultaneously achieved jointly.

[0017] A variant here provides that the coupling gear is embodied such that a support face of the backrest and a seat face of the seat part slant in force-coupled fashion rearward, by an approximate angular ratio of 1.5:1 to 2.5:1, preferably 2:1, about the pivot shaft of the basic swiveling point or downward about the pivot shaft, displaced along the guide track, of the swiveling device. A boosting ratio of about 2:1 is considered to be especially favorable ergonomically. Especially in an embodiment in which the swiveling angle of the seating face is greater than 5 and preferably greater than 10°, the swiveling angle of the backrest accordingly amounts to at least 10° and preferably 20°. In a favorable exemplary embodiment, it amounts between 24° and 30°.

[0018] A form that is structurally quite simple to achieve provides for instance that the swiveling device has a guide rail, which is guided displaceably along the fixed guide track. This should be understood to mean as much as possible telescoping components or components movable relative to one another. Such constructions can be made in quite stable form, making them also highly suitable for heavyweight persons.

[0019] To achieve the greatest possible stability on a surface, the supporting of the swiveling device on the guide track can be effected essentially centrally to a surface to stand on. The term “surface to stand on” is understood to mean the plane defined by the points of contact of the chair with the surface underneath it. For instance, if the swiveling device is to be disposed in a forward region of the seat part, then suitable devices, such as guide rails, for instance, must be provided that are then braced in the middle region relative to the surface to stand on. This leads to an optimized introduction force and to lower loads on the guide track.

[0020] Moreover, a spring device can be provided, counter to whose spring action at least the downward and rearward motion of the seat part can be effected. As a result, the seat part and, depending on the embodiment, the backrest as well return automatically to their outset position once the chair has been relieved. For seating comfort, influence can be exerted in innumerable ways by way of the spring device. The term spring device is understood to mean all constructions that are displaceable counter to a restoring force. For instance, a tension or compression spring, torsion spring, elastomer spring, and so forth could be used as the spring device.

[0021] Good integration of the spring device with the overall construction is obtained if in a variant, the spring device has an action direction which extends substantially along the guide track. The spring device therefore acts precisely in the direction of movement, so that its entire spring action comes into use rather than only some components or parts of its. If in one embodiment the guide track is to be embodied as curved, then if the spring action is not also curved but instead extends in a straight line, the best possible approximation can be achieved (tangent, chord, etc.).

[0022] Preferably, the spring device can include an adjusting unit for adjusting the spring action. As a result, the chair can be adjusted as much as possible to all weight classes and optimal spring yielding behavior can be attained. As a rule, the adjusting unit is embodied as manually adjustable via a suitable handle.

[0023] However, the option also exists of providing a damping device, which damps the swiveling motion of the swiveling device. This brings very good results especially if the swiveling device is mounted on a front end region of the seat part.

[0024] Moreover, the damping device can have an action direction which acts essentially perpendicular to a swiveling radius about the pivot shaft of the swiveling device. This provision results in an optimized introduction of force into the damping device. Since the direction of the radius in question changes constantly during swiveling, the damping device can be adapted to this swiveling path with its direction of action, or the greatest possible approximation to a rectilinear action direction can be achieved (tangent, chord, etc.). Particularly in cooperation with a spring device that has an action direction along the guide track, the result is thus action directions that extend transversely to one another and support one another when a desired forced coupling is performed.

[0025] To create a kind of rocking chair effect, the damping device can be provided with a progressively increasing damping action. This means that the longer the swiveling travel, the greater the damping action also becomes, so that a greater and greater resistance is built up. Especially in cooperation with a spring device, versatile desired spring damping actions can be achieved as a result.

[0026] The damping device can be embodied relatively economically as an elastomer cushion. An initially slight damping action can be increased arbitrarily, quite simply, with this provision. With respect to elastomer cushions, there is sufficient impetus in the prior art for suitable embodiments for attaining a particular damping action.

[0027] In general, in one embodiment, it is especially good if a spring/damping device acts on the coupling gear and furnishes a progressively increasing spring/damping force, at least in the downward and rearward motion of the seat part. The entire coupling gear is accordingly involved in this spring/damping process of the associated device.

[0028] For the requisite courses of motion, it is of further advantage if in a variant, the guide track is curved convexly toward the seat part. In particular circular-arc shaped, parabolic branchlike and other designs can be considered here.

[0029] Favorably, the averaged theoretical center of curvature of the guide track can be located below a surface on which the chair is set up. This leads to an extremely shallow guide device, since because of the curvature, relatively flat curve courses can be selected. In cooperation with the swiveling device, an economically favorable course of the inclination of the seat part can nevertheless be achieved.

[0030] Advantageously, a columnar base frame can be provided, on whose upper end region the guide track is disposed. In this case, as is usual in office chairs, for instance, five-armed columnar base frames with a middle supporting column and a caster on each end portion of a supporting arm can be used.

[0031] Preferably, the columnar base frame can also be provided with the basic swiveling point on its upper end region. In that case, the bracing of the basic swiveling point takes place immediately above the columnar base frame. The same is true for the embodiment with a guide track disposed thereon.

[0032] The columnar base frame can favorably be embodied as adjustable in height. Such mechanisms are quite familiar for office chairs and improve the overall adjustability of the chair.

[0033] Preferably, the chair can have a headrest. This is especially advantageous if the seat part and a backrest, if any, are shifted very far to the rear or pivoted very far downward. Moreover, any backrest provided need not be excessively high, to suit the same kind of purpose.

[0034] Preferably, the headrest can be joined to the seat part. This has one very particular advantage. Specifically, the headrest executes the moving or swiveling motion of the seat part, because it is joined by way of this seat part to the swiveling device that is movable along the guide track. If the chair has a backrest that is force-coupled to the seat part and that travels a longer swiveling distance than the seat part, for instance, then the headrest meets the head of the user of the chair and provides increased bracing in the event of a rearward swiveling motion of a backrest. This gives the user the feeling that the farther he pivots rearward, the better he is supported, especially in the region of his head. This lends an extremely pleasant seated feeling, particularly during the swiveling motion.

[0035] This concept is also expressed in claim 29, which relates to a chair, in particular of one of the foregoing claims. This chair includes a pivotably disposed seat part, a pivotably disposed backrest, and a forced coupling for forced-coupled, boosted swiveling of the seat part and backrest. Moreover, a headrest is provided, which is joined in movement to the seat part (directly or without boosting). Until now, it was always usual in the prior art to join a headrest to a backrest of a chair. Disposing them on a movable seat part as now lends a secure braced feeling to the user of the chair, especially when the seat part has been pivoted far downward and backward. The term “motion-connected” should be understood as being along the lines of a direct, unboosted (“immediate”) connection to the seat part (for instance, the swiveling angle and the linear movement distances are of equal size). Thus the seat part and the headrest execute a common motion, while the backrest executes a motion that is boosted relative to it.

[0036] Below, exemplary embodiments of the invention are described in further detail in conjunction with drawings. Shown are:

[0037] FIG. 1, a schematic side view of a first exemplary embodiment of an office chair, in an upright neutral position;

[0038] FIG. 2, a schematic side view of the office chair of FIG. 1, in a position inclined to the rear;

[0039] FIG. 3, a schematic side view of the office chair of FIG. 1, in a position inclined to the front;

[0040] FIG. 4, a schematic view of the office chair of FIG. 1, in which both the neutral position of FIG. 1 and the position inclined to the rear of FIG. 2 are shown;

[0041] FIG. 5, a schematic side view of a second exemplary embodiment of an office chair, in an upright neutral position;

[0042] FIG. 6, a schematic side view of the office chair of FIG. 5, in a position inclined to the rear;

[0043] FIG. 7, a schematic back view of the office chair of FIG. 5;

[0044] FIG. 8, a schematic exploded view of a third exemplary embodiment of an office chair, with a seating surface and the backrest upholstery have been left out;

[0045] FIG. 9, a full section through the guide track of the office chair, showing the seating surface, the chair being located in an upright neutral position with the highest weight setting;

[0046] FIG. 10, a view similar to FIG. 9, with the office in a position inclined to the rear;

[0047] FIG. 11, a full section through the guide track of the office chair of FIG. 8, showing the seating surface, the chair being located in an upright neutral position with the lowest weight setting;

[0048] FIG. 12, a view similar to FIG. 11, with the office in a position inclined to the rear.

[0049] The office chair 1 shown in FIG. 1 essentially includes a base region 2 and a seating region 3 located above it.

[0050] The base region 2 includes a base part 4 with five support arms 5, extending in rays away from a center, on the free end regions of which a downward protruding, pivotably disposed caster 6 is secured. In the center of the base region 2, a support column 7 projects upward. The casters 6 with their lower points of contact define a surface on which the chair sits, which when the casters 6 are placed on a floor or the like coincides with this floor or the like. Located on the upper end of the adjustable-height support column is a base block 8, which assures the coupling of the seat region 3 to the base region 2. The base block 8 on the one hand furnishes a guide track 9, which points obliquely upward and is convexly curved. The base block 8 is also provided with a basic swiveling point 10, which has a horizontal pivot shaft. The base block 8 is secured, rotatably about a vertical axis, to the upper end of the support column 7. The guide track 9 is shown only schematically. The schematic guide track 9 is meant to be understood as representative of all guide constructions along a sliding or rolling surface that allow a reinforced displacement motion.

[0051] A guide rail 11, also shown schematically, is guided displaceably along this guide track 9. The guide rail 11 is adapted in its curvature to the form of curvature of the guide track 9 and can slide in a defined way along the guide track. The averaged center of curvature of the guide rail 11 or guide track 9 is located below the theoretical surface on which the chair sits. As a result, the guide rail 11 is relatively shallow and occupies only a very slight overall height for its entire motion. It is understood that devices can be provided with which either the guide rail 11 engages the guide track 9 from behind, or vice versa, in order to assure guidance in a way that is secure against tilting.

[0052] Within the system comprising the guide track 9 and the guide rail 11, a spring device can be provided. It can be similar in design to what is shown in DE 4331987 A1 or DE 19900454 A1. However, the possibility also exists of dispensing with a degressive increase in spring force as in DE 19900454 A1. For instance, via a simple tension spring suspended from the base block 8, with its other end suspended from the guide rail 11, a desired spring action could be achieved. Reference numeral 12 indicates an adjusting handle for adjusting the spring action of the spring device. By means of this spring device, the seat region 3 is also repeatedly moved back into the position shown in FIG. 1. The adjusting handle is usually formed by a rotary knob, which is capable of adjusting a fastening base of the spring device via a threaded mechanism or gear wheel mechanism and the like.

[0053] A pivot shaft 13 with a horizontal orientation is located on the front end of the guide rail 11, which rail is a component of a swiveling device. The front end region 14 of a seat part 15 is pivotably disposed on this pivot shaft 13. The seat part 15, which is provided with an upholstered cover 16, can accordingly move, by means of the guide rail 11, along the guide track 9 in combined fashion, both rearward and downward, and in addition a swiveling motion about the pivot shaft 13 is possible. In order for this motion to be executed in forced-coupled fashion, a curvy coupling element 17 is provided, which is mounted pivotably to the basic swiveling point 10 on the base block 8 and which changes over in its upper region into a backrest 18 of the seat region 3. On its rear end region, the seat part 15 is provided with a strut 19, which in the neutral position extends vertically upward and whose upper end is pivotably connected, via a pivot point 20 with a horizontal pivot axis to the coupling element 17. The coupling gear thus created now assures a forced-guided swiveling of the seating surface 21 of the seat part 15 and of the support face 22 of the backrest 18.

[0054] It is self-evident that the reconstruction schematically shown in FIG. 1 can be constructed in just the same way symmetrically on the other side of the chair, so that some of the components described above are also present symmetrically on the other side, and the spaces in between are filled with the upholstered cover 16 and some filling, of whatever type, for the backrest 18.

[0055] Between the top side 23 of the guide rail 11 and the bottom side 24 of the seat part 15 or upholstered cover 16, there is a damping element in the form of an elastomer cushion 25, which provides a progressive damping action upon swiveling of the seat part 15 about the pivot shaft 13. The elastomer cushion 25 can be embodied in the most various ways for the desired damping action, because of its composition of material or its shaping. However, still other damping devices can also be used to attain the same or a similar effect.

[0056] The spacing between the pivot shaft 13 and the basic swiveling point 10, as well as the spacing between the pivot shaft 13 and the pivot point 20 and the spacing between the pivot point 20 and the basic swiveling point 10, and their grouping three-dimensionally relative to one another, under the influence of the shaping of the guide track 9 and the guide rail 11, assure the desired forced-coupled motion, so that upon spring yielding, the seat part 15 moves both downward and backward and simultaneously slants to the rear. The slanting is effected not only about the pivot shaft 13 but also about the averaged center of curvature, which is predetermined by the guide track 9. At the same time, however, the support face 22 of the backrest 18 slants both downward and rearward. Because of the forced coupling, a boost is created between the seating surface 21 and the support face 22. In the present exemplary embodiment, the boost in terms of the amount of angle between the support face 22 of the backrest 18 and the seating surface 21 of the seat part 15 is 2:1.

[0057] In FIG. 2, the slanting to the rear of the seat region 3 of the office chair 1 is shown again in further detail. It can be seen in particular that the guide rail 11 has been displaced rearward and downward along the guide track 9. As a result, the spacing between the pivot shaft 13 and the basic swiveling point 10 is reduced. Because of the fact that the spacing between the pivot shaft 13 and the pivot point 20, and the spacing between the basic swiveling point 10 and the pivot point 20, remain the same, the boost already mentioned above occurs, so that the support face 22 is slanted more markedly away toward the rear than is the case for the seating surface 21. In this operation, both the spring device, not identified by reference numeral, in the system comprising the spring track 9 and guide rail 11 yields both in and out (depending on whether compression or tension springs are used). In addition, a compression of the elastomer cushion 25 takes place between the top side 23 of the guide rail 11 and the bottom side 24 of the seat part 15. This elastomer cushion 25 assures that with ever-increasing motion downward and rearward, the resistance becomes greater and greater, and the chair user has the feeling of being securely seated.

[0058] From FIG. 3, it can also be seen that in addition to the neutral position, shown in FIG. 1, in which the seating surface 21 is disposed essentially horizontally, there is also the possibility of slanting the seating surface slightly forward. For instance by adjusting a stop, not identified by reference numeral, of the guide rail 11, the possibility can be attained of sliding still farther forward and upward along the guide track 9. It can be seen quite well in FIG. 3 that the adjusting handle 12 is disposed much closer to the base block 8 than in FIG. 1. A seating surface 21 inclined slightly forward is often highly desirable for many seating situations, especially in the work place. Correspondingly, the support face 22 of the backrest 18 also slants forward because of the forced coupling of the coupling gear. By the definition of certain stops, it is also possible for this position 3 inclined forward to act, at least for the spring device not identified by reference numeral, as a new neutral position, so that the office chair 1, each time it is relieved, is forced back into this position.

[0059] In FIG. 4, the action of the entire construction can be seen quite clearly from a comparison of the positions of FIG. 1 and FIG. 2. While the seating surface 21 is inclined by an angular amount α, the inclination for the support face 22 of the backrest 18 is by the angular amount β. In the present case, the angular amount β is twice as great as the angular amount α. This is accomplished, as already described above, by means of the coupling gear, and in particular the coupling element 17. It can also be seen quite well in FIG. 4 that the pivot shaft 13 moves only very slightly downward, so that the front end region 14 likewise drops only very slightly, while conversely the rear region of the seating surface 21 has been lowered considerably.

[0060] At this point it should be noted that the angular amount α has an apex that is displaced from the pivot shaft 13. This is accomplished by the combination motion along the guide track 9.

[0061] By means of the construction of the invention, an office chair 1 can be achieved that among other things, from ergonomic points of view, furnishes an optimized swiveling or slanting behavior with the stablest possible construction. The boosting, desired for ergonomic reasons, between the seating surface 21 and the support face 22 of the backrests 18 does not cause excessive lowering of the seating surface 21. On the contrary, a pleasing rocking effect with progressively increasing spring force is attained, so that an unpleasant sensation of tilting backward and away is averted.

[0062] In addition, a headrest, armrests, an adjustment of the height of the backrest, lumbar support, and a seating depth adjustment in this sentence] can also be provided on the chair. Other setting options, of the kind found especially in the field of office chairs, are also possible. Locking means can also be present that allow locking the seat part or the backrest in any arbitrary position or in preselected positions.

[0063] Below, in conjunction with FIGS. 5-7, a second exemplary embodiment of an office chair 1 of the invention will be described in further detail. Only the essential distinctions from the previous exemplary embodiment will be addressed, and therefore with respect elements that are structurally or functionally the same, reference is made to the preceding description. For this reason, the same reference numerals are used for structurally or functionally identical components.

[0064] Along with the somewhat different disposition of the support arms 5 of the base part 4 and a thicker support column 7, in which a spring damping device that is already usual for office chairs is disposed, the office chair 1 is distinguished among other factors by its rectilinear guide track 9. The guide rail 11 is guided in a guide track 9 that is embodied as a C-profile 27 standing on its head. As a result, a spring-damping mechanism is completely covered at the top by the closed crossbar 26 of the C-profile 27 (see in particular FIG. 7). The elastomer cushion is therefore likewise disposed inside the region enclosed by the C-profile 27. The handle 12 for adjusting the neutral position is mounted in the front region, in the vicinity of the pivot shaft 13. The handle 12 acts on a spindle 28, which brings about the desired adjustment between the guide rail 11 and the C-profile 27.

[0065] A further substantial distinction from the preceding exemplary embodiment is the embodiment of the strut 19 of the seat region 3, which is now guided via an adapter 29 toward the pivot point 20. In the basic position shown in FIG. 5, the strut 19 extends parallel to a region of the coupling element 17 that changes over into the backrest 18, while the adapter 29 extends perpendicular away from the strut 19 toward the pivot point 20. Because of this form of the strut 19, a lateral limitation of the seat region 3 is created, and the strut 19, on its upper end, changes over into an armrest 30. The armrest extends essentially parallel to the seating surface 21.

[0066] The exemplary embodiment shown in FIGS. 5-7 has a cushioned headrest 31, which is positioned above the upper end of the backrest 18. The headrest 31 is disposed on a swivel recess 32, but the swiveling can take place only counter to a resistance, for instance in the form of a multiple detent fastening. The swivel recess 32 is adjoined by a slip-on holder, which is slipped onto the upper end of a retaining strut construction 34. The retaining strut construction 34 can involve two struts, or a single strut produced by bending. Beginning at the slip-on holder 33, in the basic position of the chair, the strut construction extends essentially parallel to the backrest 18. The free ends 35 of the strut are then extended to the outside and to the pivot points 20. The free ends 35 of the strut are joined in the region of the pivot point 20 to the adapter 29 and as a result to the seat region 3. Accordingly, the headrest 31 together with the seating surface 21 executes the same swiveling and rearward motion. This means that the swiveling angle of the seating surface 21 that can be found from a comparison of FIGS. 5 and 6 is the same as the swiveling angle of the headrest 31. In contrast to this, the backrest 18 pivots in the usual way, at the boosting ratio selected here, by twice the angular amount by means of the coupling gear. It can be seen clearly in FIG. 6 that as a result, compared to the upper end of the backrest 18, the headrest 31 protrudes farther than is the case in FIG. 5. Accordingly, on rearward swiveling of both the seat part 15 and the backrest 18, the headrest 31 moves toward the head of the user of the chair relative to the backrest 18. This gives the user of the chair the feeling that on swiveling backward, there is greater head support, thus lending a secure seated feeling on swiveling backward.

[0067] In principle, the headrest 31 can also be provided with a height adjustment, which can be executed for instance via the slip-on holder 33 and suitable shaping of the retaining strut construction 34 in the upper slip-on region. The retaining strut construction 34 is preferably a bent metal bar, resulting in a relatively stable support.

[0068] Below, in conjunction with FIGS. 8-12, a third exemplary embodiment of an office chair 1 of the invention will now be described in detail. Only the essential distinctions from the preceding exemplary embodiment will be addressed, and the preceding description is therefore referred to where there is structural identity or elements that function the same. For this reason, the same reference numerals are used for structurally or functionally identical components.

[0069] The base block 8 in the present case comprises a bent sheet-metal part 36 and two box guides 37 disposed parallel to one another. The box guides 37 have a U-shaped cross section, so that a helical tension spring 38 disposed below each of them is received in their cross section. The front end of the box guides 37 is closed by a retaining plate 39. One end of the associated helical tension spring 38 is secured to the inside of each retaining plate 39. A receptacle 40 for a fastening peg 41 is provided in the middle of the bent sheet-metal part 36. The rotation relative to the base part 4 is effected in the usual way inside the support column 7. Suitable systems for the embodiment of such support columns 7 are extremely well known and are in wide use.

[0070] The guide rail 11 is formed by a pair of side rails 42, which are joined together on their rear end via a reinforcing frame 43. The guide rail 11 further includes a rail cover 44, which is embodied as a plastic part. The side rails 42 and the reinforcing from 43 are disposed inside the rail cover 44. The side rails 42 rest, spaced apart parallel from the side walls 45 of the rail cover 44, on protrusions 46. The underside of the rail cover 44 therefore slides along the top side of the box guides 37, while the side rails 42 are guided laterally along the box guides 37 that are open from the back side. The fastening of the box guides 37 to the bent sheet-metal part 36 is effected via the centrally disposed fastening receptacle 40. The frame 43 is embodied such that it can come into contact with the rear end face of the box guides 37 and thus serves as an end stop for the neutral position of the office chair (as will be described in further detail below).

[0071] A damper block receptacle 47, in which the elastomer cushion 25 is disposed, is located in the front region of the rail cover 44. Located below this receptacle 47 is a threaded bore 48, extending parallel to the direction of motion of the guide track 9. The spindle 28 is received in a manner capable of being screwed in and out in this threaded bore 48. The top of the spindle 28 is retained rotatably on a transverse rail 49, which is joined to the front ends of the side rails 42. An adjusting handle 12 and a movement mechanism, not identified by reference numeral, for instance in the form of a worm wheel engaging the spindle 28, is disposed on this transverse rail 49 in order to move the spindle 28. Rotation of the adjusting handle 12 causes the spindle 28 to rotate about its axis, so that the rail cover 47 moves along the spindle 28. The ribs 50 extending along the side rails 42 parallel to one another, in cooperation with the pegs 51 disposed laterally on the box guides 37, provide a means of securing the guide track 9 against lifting away.

[0072] The second end of the tension spring 38 is secured on a rear, closed end of the rail cover 44. For reasons of appearance, a covering hood 52 is also placed over this construction of the rail cover 44.

[0073] A press-on rail 53, which can be brought into contact with the elastomer cushion 25, is mounted on the frame of the seat part 15, in the front region.

[0074] The elastomer cushion 25 protrudes past the top side of the rail cover 44 and the covering hood 52 and can be compressed by the press-on rail 53.

[0075] Although the third embodiment is shown without armrests or a headrest, it is understood that it can also be equipped with these structural elements as in the preceding description for the second exemplary embodiment.

[0076] Below, in conjunction with FIGS. 9-12, the course of motion along the guide track 9 of the third exemplary embodiment will be described in further detail.

[0077] In FIG. 9, an upright neutral position is shown. Via the adjusting handle 12, the rail cover 44 has been moved all the way to the rear and downward, so that the tension springs 38 are maximally prestressed in the neutral position. In the neutral position, the reinforcing frame 43 comes into contact with the back side of both the box guides 37 and the fastening receptacle 40. The elastomer cushion 25 is completely depressurized, but is located virtually nearly in contact with the underside of the press-on rail 53. Beginning at this neutral position, the chair is now put under load and shifted into a rearward-slanting position as shown in FIG. 10. It can be seen clearly that the tension springs 38 are now still further stressed. The movement travel of the rail cover 44 relative to the box guides 37 can be estimated from the spacing of the reinforcing frame 43 from the back side of both the box guides 37 and the fastening receptacle 40. The box guides 37 therefore project relatively far out of the rail cover 44. The impact of the receptacle 29 against the fastening receptacle 40 dictates a precisely defined terminal position for the swiveling back again or the rearward displacement along the guide track 9.

[0078] The elastomer cushion 25 is now compressed considerably by the press-on rail 53. In cooperation with the tension springs 38, a progressive spring/damping action now results, lending the user of the chair a secure feeling as he pivots rearward. Pressing the press-on rail 53 onto the front region of the elastomer cushion 25 causes this rail to develop its complete damping action.

[0079] FIG. 11 differs from FIG. 9 solely in that the rail cover 44 has been displaced into its forwardmost position via the adjusting handle 12. As a result, the press-on rail 53 is already in contact with the middle region of the elastomer cushion 25, in the neutral position shown in FIG. 11. Upon swiveling to the rear and displacement downward along the guide track 9 into the position shown in FIG. 12, the press-on rail 53 now comes to be operatively connected to only part of the elastomer cushion 25, and therefore the damping behavior is also differently pronounced. Also, in the neutral position shown in FIG. 11, the tension springs 38 are no longer prestressed as far as in FIG. 9. This setting is especially well suited to lightweight persons, while conversely the setting of FIG. 9 is suitable for heavyweight persons. Also in the setting of FIGS. 11 and 12, suitable stop means assure a stop in the position shown in FIG. 12.

[0080] It should further be noted that because of the shaping of the elastomer cushion 25 and of the press-on rail 53, versatile damping behaviors can be created. The property of the material comprising the elastomer cushion 25, as well as its design and structure, also make it possible to vary the damping behavior. Depending on the neutral position shown (setting via the adjusting lever 12), the press-on rail 53 can be capable of being pressed onto variously designed elastomer cushions 25 (both in terms of the material and the shape or structure of the elastomer material), so that over the course of the swiveling of the seating surface 21, a predetermined damping course can be obtained. The elastomer cushion 25 can also be embodied of different kinds of materials, as composition material.

Claims

1. A chair, especially an office chair, having a seat part (15) and a downward-slanting guide track (9) for furnishing a combined downward and rearward motion or a combined upward and forward motion for the seat part (15), characterized in that a swiveling device with an at least horizontal pivot shaft (13) is provided for pivotably disposing the seat part (15), and the swiveling device together with the seat part (15) is disposed as movable along the guide track (9).

2. The chair of claim 1, characterized in that the guide track (9) is embodied as a sliding or rolling track.

3. The chair of claim 1 or 2, characterized in that the maximum displacement travel of the swiveling device along the guide track (9) is greater than 30 mm, preferably 60 mm.

4. The chair of one of claims 1-3, characterized in that the maximum swiveling angle about the pivot shaft (13) of the swiveling device is greater than 5°, preferably 10°.

5. The chair of one of claims 1-4, characterized in that a coupling gear is provided, which force-couples the displacement motion along the guide track (9) and the swiveling motion about the pivot shaft (13) of the swiveling device.

6. The chair of claim 5, characterized in that in a downward and rearward motion of the seat part (15), a swiveling motion about the pivot shaft (13) of the swiveling device is effected, to reinforce the downward motion of a rear seat part region.

7. The chair of one of claims 1-6, characterized in that the pivot shaft (13) of the swiveling device is disposed on a front seat part region (14).

8. The chair of one of the foregoing claims, characterized in that the coupling gear includes a coupling element (17), which on the one hand is disposed pivotably about a basic swiveling point (10) with a horizontal swivel shaft spaced apart from the pivot shaft (13) of the swiveling device, and on the other hand is disposed spaced apart from the basic swiveling point (10) via a pivotable connection (20) with a horizontal pivot shaft, with the seat part (15) also spaced apart from the pivot shaft (13) of the swiveling device.

9. The chair of claim 8, characterized in that the guide track (9) and the basic swiveling point (10) for the coupling element (17) are disposed stationary relative to one another.

10. The chair of claim 8 or 9, characterized in that the coupling element (17) is embodied as a component part of a backrest (18).

11. The chair of claim 10, characterized in that the coupling gear is embodied such that a support face (22) of the backrest (18) and a seat face (21) of the seat part (15) slant in force-coupled fashion rearward, by an angular ratio of 1.5:1 to 2.5:1, preferably 2:1, about the pivot shaft of the basic swiveling point (10) or downward about the swivel shaft (13), displaced along the guide track (9), of the swiveling device.

12. The chair of one of claims 1-11, characterized in that the swiveling device has a guide rail (11), which is guided displaceably along the fixed guide track (9).

13. The chair of one of claims 1-12, characterized in that the supporting of the swiveling device on the guide track (9) is effected essentially centrally to a surface to stand on.

14. The chair of one of claims 1-12, characterized in that a spring device is provided, counter to whose spring action at least the downward and rearward motion of the seat part (15) is effected.

15. The chair of claim 14, characterized in that the spring device has an action direction which extends substantially along the guide track (9).

16. The chair of claim 14 or 15, characterized in that the spring device includes an adjusting unit (12) for adjusting the spring action.

17. The chair of one of claims 1-16, characterized in that a damping device (25) is provided, which damps the swiveling motion of the swiveling device.

18. The chair of claim 17, characterized in that the damping device (25) has an action direction which acts essentially perpendicular to a swiveling radius about the pivot shaft (13) of the swiveling device.

19. The chair of claim 17 or 18, characterized in that the damping device (25) is provided with a progressively increasing damping action.

20. The chair of claim 19, characterized in that the damping device (25) is embodied as an elastomer cushion.

21. The chair of one of claims 5-20, characterized in that a spring/damping device acts on the coupling gear and furnishes a progressively increasing spring/damping force, at least in the downward and rearward motion of the seat part (15).

22. The chair of one of claims 1-21, characterized in that the guide track (9) is curved convexly toward the seat part (15).

23. The chair of claim 22, characterized in that the averaged theoretical center of curvature of the guide track (9) is located below a surface on which the chair is set up.

24. The chair of one of claims 1-23, characterized in that a columnar base frame is provided, on whose upper end region the guide track (9) is disposed.

25. The chair of one of claims 1-24, characterized in that the averaged theoretical center of curvature of the basic swiveling point (10) is located below a surface on which the chair is set up.

26. The chair of claim 24 or 25, characterized in that the columnar base frame is embodied as adjustable in its height.

27. The chair of one of claims 1-26, characterized in that a headrest (31) is provided.

28. The chair of claim 27, characterized in that the headrest (31) is joined to the seat part (15).

29. The chair, in particular of one of the foregoing claims, having a pivotably disposed seat part (15), a pivotably disposed backrest (18), and a forced coupling for forced-coupled, boosted swiveling of the seat part (15) and backrest (18), characterized in that a headrest (31) is provided, which is motion-joined to the seat part.