EP1258210B1 - Synchronised mechanism for a coupled seat- and backrest-movement in an office chair - Google Patents

Abstract

The joint between the base and seat supports (2,6) consists of a slotted (25) twist joint (22). The slot also contains the seat support (6) bearing pin (26) so the joint (22) has to be moved horizontally back in the slot to lower the seat support. The joint as such is integrated with the front joint (12) between the front rod (8) and backrest support (7) and the interval (a) between joints (12 and 13) and rods (7,8) equals the length (L) of the rear rod (10) and is greater than the length (L8) of the front rod (8).

Description

The invention relates to a synchronous mechanism for a correlated seat-backrest movement of an office chair with the features specified in the preamble of claim 1, as are known from DE 199 21 153 A1.

The term "synchronous mechanism" assemblies in the seat substructure of an office chair are understood, which provide for a coupled, a certain relative movement of the seat and backrest with each other bringing kinematics. For this purpose, a base support is placed on a chair column, on which on the one hand a pivotable about a transverse axis, hingedly connected to the base support seat support and on the other hand also pivotable about a transverse axis, hingedly connected to the base support backrest support are mounted. On the seat support of the usually provided with a padded seat seat of the office chair is mounted. The backrest support, which extends in a conventional manner from the actual synchronizing mechanism to the rear, carries on an upwardly extending arm, the backrest of the office chair.

Seat support and backrest support are coupled so articulated that a pivoting movement of the backrest to the rear - as it can be hervorgeruten example, by leaning the Sruhlbenutzer to the backrest - induced a lowering movement of the rear edge of the seat down. This correlated seat-back movement provides a significant comfort advantage and is desirable for orthopedic reasons.

A common problem with synchronizing mechanisms according to the prior art is the often very limited pivoting angle of the backrest. In addition, the lowering of the seat is often too low, even with a relatively large backrest tilt angle, which is due to the pivotal mounting of the seat and backrest support in each case only one pivot joint on the base support.

The above objectives are achieved in the case of the above-mentioned publication provided for storage of the backrest support via a link assembly on the base support, which defines a four-bar chain. The handlebar assembly consists of two hinged to the base support arms and the backrest support itself as a coupling of the four-bar chain. The longitudinal axes of the two links are in an upwards to the seat opening, acute angle.

By the above storage of the backrest support in the form of a four-bar linkage, a large swing angle is basically achievable, the backrest support not only rotates about a fixed pivot axis, but performs an additional tilting movement to the rear. This turn-tilt movement is pronounced by the upwardly opening handlebars pronounced possible.

It is further provided that the seat support is articulated at its front end region via a welteren handlebar on the base support. In the upright position of the synchronizing mechanism, this handlebar is inclined forward. With its rear end portion of the seat support is hinged to the backrest support.

Due to the forwardly inclined arrangement of the front arm results that starting from the upright position of the synchronous mechanism - ie the basic position - the seat with its leading edge performs at least at the beginning of the correlated seat backrest movement a pronounced lifting movement upwards. This has the effect that the user must operate when pressing the synchronous mechanism by pushing back the back against his own, resting on the seat weight.

Due to individually different preferences from person to person, this effect is sometimes felt to be detrimental. This also applies to the above-mentioned pronounced lifting movement of the seat support and thus the seat of an office chair at the beginning of the seat-back synchronous movement.

Finally, the articulated mounting of the seat support with a total of three pairs of handlebars on both sides of the seat-mid-longitudinal plane is a relatively complicated construction.

From DE 198 10 768 A1 a synchronous mechanism is known in which the backrest support is articulated in a single hinge point on the base support and thus performs a pure pivoting movement. The seat support this synchronizing mechanism is coupled at the rear end via a hinge point with the backrest support. At the front end, it is guided in a obliquely from the bottom front to the rear upward rising slot control cam. Overall, this backrest seat support articulation is indeed structurally simple, but also has a relation to the practical requirements less well-adapted kinematics. In particular, the rising slot control cam for supporting the front end of the seat support leads to the already in connection with the Construction according to DE 199 21 153 A1 discussed stroke movement of the seat leading edge.

Based on the problems described in the prior art, the present invention seeks to improve a synchronous mechanism of the generic type so that the initial stroke movement of the seat support is avoided under structural simplification.

This object is achieved according to the characterizing part of claim 1 by the formation of the joint between the base support and seat support at the front end as a rotary-sliding joint, which is designed so that the lowering movement of the seat support is superimposed on a horizontal sliding movement to the rear. Preferably, the rotary-sliding joint is formed by a horizontal, running in the longitudinal direction of the seat, slot-like link in the seat support, in which a bearing pin of the seat support is guided

By the above-discussed interpretation of the articulated connection of the seat support to the base support on the one hand, the above-discussed lifting movement is avoided, which brings the desired comfort improvement with it. Furthermore, a rotary-sliding joint, in particular in the embodiment shown above, is structurally very simple to realize.

Further preferred embodiments, which relate to the arrangement and dimensioning of the joints and links of the four-link chain provided between the base support and the backrest support or seat support, serve to achieve a particularly compact design with a comparatively larger prior art according to DE 199 21 153 A1 Ratio of the swivel angle of the backrest to the swivel angle of the seat support.

Finally, the base support by the outside attachment of the handlebar and the backrest support member also very compact and serve as a central "backbone" of the synchronous mechanism. It is created by the preferred embodiment of the handlebars as a widened fabric on the one hand, an additional design element, on the other hand reliably prevents jamming of the fingers in the synchronous mechanism from a health and safety point of view.

Fig.1

eine schematische Seitenansicht der Synchronmechanik in Grundstellung,

Fig. 2

eine Seitenansicht analog Fig. 1 in nach hinten geschwenkter Stellung der Synchronmechanik und

Fig. 3

eine schematische Draufsicht auf die Synchronmechanik gemäß Fig. 2.

Further features, details and advantages of the invention will become apparent from the following description in which an embodiment of the subject invention is explained in detail with reference to the accompanying drawings. Show it:

Fig.1

a schematic side view of the synchronous mechanism in basic position,

Fig. 2

a side view similar to FIG. 1 in the rearwardly pivoted position of the synchronous mechanism and

Fig. 3

a schematic plan view of the synchronizing mechanism of FIG. 2.

The basic structure of the synchronous mechanism designated as a whole by 1 is to be explained with reference to FIGS. 1 and 3. It therefore has a base support 2, which is set by means of a cone seat 3 on the upper end of a chair column 4. Outside and above the side, 1. Core pieces thereof are, on the one hand, a substantially frame-shaped seat support 6 and a backrest support 7, which is fork-shaped in plan view. The seat support 6 is provided with a padded seat (not shown) ) assembled. The backrest support 7 holds on an angled cross member 18 a backrest, also not shown, which is height adjustable in modern office chairs.

As is clear in particular from FIG. 3, the entire synchronizing mechanism 1 is of mirror-symmetrical design with regard to the central longitudinal plane M with regard to the actual kinematics. In that regard, in the following description always be based on both sides pairwise existing construction elements.

The backrest support 7 is thus connected via a link arrangement articulated to the base support 2. This link arrangement has a first link 8, which is articulated approximately centrally on a pivot bearing 9 on the base support 2. A second link 10 is mounted between the front link 8 and cone seat 3 on a pivot bearing 11 on the base support 2. The free ends of the two links 8, 10 are coupled via joints 12, 13 with the backrest support 7. The two pivot bearings 9, 11 and the joints 12, 13 define a four-bar chain, in which the backrest support 7 with its respective fork leg 14 itself forms the coupling. In the illustrated in Fig. 1 basic position of the backrest support 7 of the front arm 8 is approximately vertically upwards, while the rear arm 10 is inclined backwards. The two longitudinal axes 15, 16 of the links 8, 10 extending through the articulation points form an acute angle W (FIG. 1) of FIG a little over 30 °. The length ratio between the front and rear links 8, 10 is about 2.5: 3. Due to the above interpretation and arrangement of the four-bar chain performs the backrest support 7 in Fig. 1 indicated by the arrow 17 superimposed rotary and pivotal movement back down ,

As is further apparent from Fig. 1, the seat support 6 is coupled in front of its rear end 19 with the backrest support 7 via a bearing eye 20 to the front joint 12 forming axis and articulated so with its rear end portion. The joint between seat support 6 and backrest support 7 is thus integrated into the front joint 12 between the handlebar 8 and the backrest support 7. At its front end region 21 - thus left in Fig. 1 - the seat support 6 is connected to the base support 2 via a designated as a whole with 22 rotary-sliding joint. This consists on the one hand of a in the two longitudinal bars 23, 24 (Fig. 3) molded, slot-like link 25, on the other hand from the inside a bearing pin 26 engages. The latter is in each case formed on a bearing extension 27 of the base support 2 and is at right angles to the central longitudinal plane of M from this outwards and into the slot 25 into it.

The synchronous mechanism 1 is biased by a spring arrangement F opposite to the arrow 17 - ie to the basic position of the synchronous mechanism 1. This spring arrangement F is in the form of two transversely aligned leg springs 28 (Fig. 3) which are positioned about the pivot bearing 9 of the front link 8 forming axis. The upwardly pointing leg 29 is supported on a projection 30 on the seat support 6, while the second, forwardly extending leg 31 is supported in an adjustment mechanism 32 in the base support 2. The torsion springs 28 exert a spring force against the rearward Pivoting movement of the backrest, which is variable by the adjusting mechanism 32 by means of actuation by a rotary lever 33.

As will now be apparent from a comparison of Figs. 1 and 2, the backrest support 7 performs at a loading of the backrest to the rear indicated by the arrow 17 pivoting rotational movement to the rear bottom, with the rear arm 10 of the four-bar chain on to the rear and the front handlebar 8 also turn backwards. At maximum pivoting angle of the backrest support 7, the angle W between the longitudinal axes 15, 16 of the two links 8, 10 is approximately 20 ° (FIG. 2). The four-bar linkage thus, so to speak, folds in relation to the further spread starting position according to FIG. 1, so that this already compact arrangement is further reduced in size.

Contributing to the compact arrangement also contributes that the distance a of the two joints 12, 13, sitting between the backrest support 7 and the arms 8 and 10, approximately equal to the length L 10 of the rear arm 10 and in the ratio already indicated greater than the length L8 of the front link 8 is.

By the mentioned pivoting movement of the four-bar chain with the backrest support 7 and the seat support 6 is also abgesohwenkt both backwards down and moved horizontally in the region of the rotary sliding joint 22 to the rear. This results in no relevant lifting movement of the front end 21 of the seat, whereby any constrictions or pressure on the underside of the thighs are avoided.

The synchronous mechanism 1 is otherwise designed so that in the swung-back end position shown in Fig. 2, the backrest support 7 passes through a pivot angle W7 of about 26 °, while the pivot angle W6 of the seat support 6 is about 15 °. It is noteworthy that changes the ratio of the tilt angle of the backrest and seat support during the pivoting movement. Thus, the ratio is initially at a value of about 3.5: 1, reduced about in the middle of the pivoting range to values around 2: 1, and finally at the end, ie at maximum pivoting, a ratio W7: W6 of about 1, 8: 1 to reach. This has the advantage that a high Absenkwinkel of the seat support can be achieved without the tilt angle of the backrest must be too large, which would lead to a lie-like position. The reason for this low end ratio of the swivel angle is the sliding movement of the seat support during lowering. Thus, the so-called "shirt extraction effect" is effectively avoided.

As is clear from Fig. 1 and 3, the externally mounted on the seat support 6 handlebars 8, 10 are formed as widened fabric approximately in kidney shape, wherein they are in all pivot positions between the two positions shown in FIG. 1 and 2 mutually and in conjunction with overlap the outside of the arms 8, 10 engaging bearing cheeks 34 of the fork-like backrest support 7 such that no Durchgriffsmöglichkeiten between links 8, 10, base support 2 and backrest support 7 are present. Thus, the fingers of the person sitting on the chair are effectively protected against pinching when pivoting the synchronous mechanism.

In a manner not shown is the synchronous mechanism 1 in different positions between the basic position (Fig. 1) and the maximum pivoted to the rear position (Fig. 2) detectable. The corresponding locking device is not explicitly shown in the figures and needs - since it belongs to the prior art - no detailed discussion. It is merely noted that the determination is carried out with the further operating lever 35 on the side of the rotary lever 33. The seated on the other side operating lever 36 is used to trigger the height adjustment of the chair column. 4

Claims (6)

1. A synchronizing mechanism for correlated seat/backrest motion of an office chair, comprising

   - a base carrier (2) to be placed on a chair column (4);

   - a seat carrier (6), which is pivotable about a transverse axis and, at its front end (21), articulated to the base carrier (2);

   - a backrest carrier (7), which is also pivotable about a transverse axis and articulated to the base carrier (2) and which is coupled with the seat carrier (6) such that a backward pivoting motion of the backrest induces a lowering motion of the rear end of the seat carrier (6);

   -- the backrest carrier (7) being pivotably mounted on the base carrier (2) by a cam arrangement (8, 10) that defines a four-bar chain;

   -- the cam arrangement (8, 10) being comprised of front and rear cams (8, 10) that are articulated to the base carrier (2) and of the backrest carrier (7) itself as a coupling of the four-bar chain; and

   -- the seat carrier (6), by its rear end (19), being articulated to the backrest carrier (7);

   
   characterized

   - in that the joint between the base carrier (2) and the seat carrier (6) is a turning and sliding joint (22) so that the lowering motion of the seat carrier (6) is combined with a horizontal sliding motion to the rear.
2. A synchronizing mechanism according to claim 1,
   characterized
   in that the turning and sliding joint (22) comprises, in the seat carrier (6), an oblong-hole-type connecting member (25) which extends in the longitudinal direction and in which a bearing journal (26) of the seat carrier (6) is guided.
3. A synchronizing mechanism according to claim 1 or 2,
   characterized
   in that the link between the seat carrier (6) and the backrest carrier (7) is integrated into the front joint (12) between the front cam (8) and the backrest carrier (7).
4. A synchronizing mechanism according to one of claims 1 to 3,
   characterized
   in that the distance (a) of the two joints (12, 13) between the backrest carrier (7) und the two cams (8, 10) is approximately equal to the length (L10) of the rear cam (10) and greater than the length (L8) of the front cam (8).
5. A synchronizing mechanism according to one of claims 1 to 4,
   characterized
   in that the cams (8, 10) are mounted externally on the seat carrier (6) with the backrest carrier (7) being attached thereto by way of bearing cheeks (34) that are applied externally on the cams (8, 10).
6. A synchronizing mechanism according to claim 5,
   characterized
   in that, in a plan view related to their joint axis, the cams (8, 10) have a widened sheet configuration so that in none of the pivoted relative positions of the four-bar chain formed thereby, there is a possibility of reach-through between the cams (8, 10), base carrier (2) and backrest carrier (7).

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