EP0535262B1 - Adjustable chair which is adaptable to a person's stature, particularly rotatable chair - Google Patents

Abstract

In a chair, in particular a rotatable chair, a simultaneous adjustment of the height of the backrest, the height of the armrest and the depth of the seat can be achieved by mounting the backrest on steep lateral bearing arms (18) and, furthermore, to improve the ergonomic features the synchronous mechanism can be put out of action in the furthest forward position of the backrest by a stiff support of the seat (14) which is only released when the backrest is tilted backwards to a relatively great extent. <IMAGE>

Description

The invention relates to a multi-adjustable, adaptable to the size of the chair, in particular swivel chair, in which the seat back independent of the seat is held by two support arms that extend from a first transverse axis under the seat laterally from this to the rear and variable in length as in different lengths can be determined by a locking device.

A chair of this type is known from DE 33 23 171 A1. The well-known chair already has an adjustable seat height. Moreover, the support arms designed as a hollow tube, which form an angle of 30 ° with the horizontal here, mean that when the height of the backrest is raised above the seat, the seat depth increases at the same time. Moreover, in this previously known chair, neither the backrest nor the seat can be tilted.

Permanent mechanics and synchronous mechanisms are also known. In the case of permanent mechanics, the seat is rigidly connected to the chair base, i.e. cannot be tilted, while the backrest is attached to the chair base so that it can be tilted against the action of a spring. With the permanent mechanism, the backrest can thus be optimally matched to the back regardless of the seat. Since the rigid seat does not follow the movements of the backrest, there are also considerable disadvantages. In the synchronous mechanism, the seat and backrest are coupled in such a way that when the backrest is returned, the seat is also tilted backwards. However, this leads to the fact that with synchronous mechanisms, the seat weight portion already causes the backrest to tip backwards even in the front sitting position, so that it loses its supporting effect.

To avoid this disadvantage, it is already known (DE GM 85 29 663) to arrange levers and an additional spring between the support of the backrest and the support of the seat, which gives the backrest in the rest position an increased resistance to pivoting.

A chair with synchronous mechanism (DE 38 17 761 C2) is also known, in which the backrest is held by two support arms running on both sides of the seat at approximately 40 ° to the rear, which are in their foremost region, i.e. under the front edge of the seat rigid seat supports are pivotally mounted. Between this pivot axis and the connection of the support arms to the backrest, a downwardly projecting mounting bracket is provided, on which the seat with its central region is rotatably mounted.

Finally, it is also known (DE 40 18 436 A1) to connect an armrest of the chair to these support arms in chairs whose backrest is supported by support arms which run obliquely backwards.

Experience shows that the public is unable to take advantage of numerous adjustment options on chairs. Furthermore, it also appears desirable to maintain the advantage of permanent mechanics in the case of a chair with synchronous mechanism in terms of active lordosing back support which is unaffected by the weight of the seated person. Finally, it must be ensured today that one and the same chair is suitable for people of very different sizes (cf. DIN 33402) without any major redesign, whereby the compromise values (DIN 4551) should be improved as far as possible.

The object of the invention is therefore to propose a chair with synchronous mechanism in which the seat depth, backrest height and armrest height can be adjusted at the same time and the synchronous mechanism in the front seat posture is automatically locked so that the seat force does not lead to a reduction in the support effect of the backrest on the back.

This object is achieved by the invention characterized in the claims.

It can be seen first of all that the backrest is supported by two support arms which are mounted on the seat and extend laterally from this to the rear and are variable in length and which can be locked in different lengths by a locking device. This adjusts the seat depth and backrest height at the same time. If, according to a special feature of the invention, the upper part of the telescopically subdivided, length-adjustable support arm is also provided with an armrest, then the armrest height is also adjusted at the same time. The seat depth, backrest height and armrest height can thus be adjusted synchronously with a single, sensible adjustment. As a result, a single chair construction can also be made accessible to an extremely wide range of user sizes, since there is a particularly large size change range.

This size change range is decisively shaped by the fact that the support arms form an angle of at least 45 °, preferably over 50 ° and at least almost 52 ° with the horizontal in the rest position. Because in this way a height adjustment range of the upper support point of the iliac crest of 180 - 230 mm is achieved. At the same time, the armrest has a height adjustment range of 200 to 260 mm above the seating point and the seat depth can also be changed over a wide range. Given the steep position of the support arms, the optimal articulation point for their lower ends is at a distance of one third of the seat depth from the front edge of the seat.

In order to achieve the desired synchronous mechanism, the seat is first mounted in the mechanical housing in the usual manner at its front end about a horizontal axis. The seat is also pushed up by a spring, just as another spring pushes the backrest forward. It is crucial, however, that in the normal upright position of the backrest the synchronizing mechanism is rendered ineffective in that a rigid support is set between the mechanism housing and the seat at a distance from the pivot axis of the seat. This is designed so that it is only released when the backrest is clearly and deliberately deflected by the user to the rear, and then the synchronizing mechanism can take effect. First of all, the rigid support does not have any effect on the load on the seat by the user on the backrest. This does not swing back when the user sits down, nor is the force of the spring pushing the backrest forward reduced. Thus, the advantages of permanent mechanics and synchronous mechanics are actually combined in one chair with easy adjustment.

It is also crucial that this is achieved with an uncomplicated mechanism. It is crucial also on the simple construction of the rigid support of the seat in the foremost position of the backrest. This takes place via two levers which are connected to one another in an articulated manner and with their respective other ends, one on the underside of the seat, the other on the mechanism housing or on the chair foot. The two levers should align with each other in the rest position so that they form a rigid support member. In the transverse axis which connects the two levers in an articulated manner, the lower end of the support arms, which are articulated under the seat, now acts directly, but generally indirectly. If the user leans back on the initially rigidly supported seat and swivels the support arms due to the pressure on the backrest, they pull on the transverse axis connecting the two aligned levers, thus lifting the seat support after a certain swivel angle and gradually so that the chair then functions like a chair with the usual synchronous mechanism.

The construction becomes particularly simple if, for this purpose, the support arms are extended beyond their articulation under the seat and each carry a swivel plate, which itself, or preferably via another, on the one hand on the swivel plate and on the other hand on the transverse axis between the two levers the support articulated pull lever is connected to it and thereby dissolves or sets it up.

The entire kinematics explained are free of power linkages. Of course, as already mentioned above, this chair is also pushed upwards by a spring and the backrest is pushed forward. The spring pushing the seat upwards is inserted between the mechanical housing acting as the support and the seat, the point of application of this spring pushing the seat upwards being in the vicinity of the transverse axis arranged thirdly below the seat from its front edge.

It is obvious that the spring for pushing the backrest forward must also be conveniently accommodated in the supporting mechanical housing under the seat. They are also allowed to attack the swivel plates of the support arms for this purpose. By appropriate design of the articulation it can be achieved that the direction of action of the spring in the adjustment range in question is always as close as possible to the optimal direction of action of the spring.

Mechanical springs are used as springs, which have the advantage of the progressive effect compared to the almost linear identification of a gas spring: with increasing deflection, the restoring force increases. This is particularly important for the restoring force on the backrest for ergonomic reasons.

Finally, the seat is given an inclination of 3 to 4 ° forward in the rest position. This is the starting point for the synchronous kinematics after the support of the seat has been released, so that a pre-rotation of the pelvis is initiated to straighten the spine. The specified forward tilt is a compromise between this effect achieved and a limitation of the forward tilt to a value which prevents the user from sliding forward from the seat.

Finally, it should be pointed out that the construction chosen for this chair makes the seat depth adjustment completely independent of the seat angle, so that a seat angle adjustment independent of the seat depth adjustment is also achieved.

Further details and advantages result from the following description of the drawing.

Fig. 1

eine Ausführungsform des erfindungsgemäßen Stuhls mit Veranschaulichung verschiedener Verstellmöglichkeiten

Fig. 2

eine Veranschaulichung des weiten Anpassungsbereiches des Stuhls an verschiedene Körpergrößen,

Fig. 3

eine Ausführungsform der erfindungsgemäßen Sperrung der Synchronmechanik in vorderster Position der Rückenlehne, und

Fig. 4

eine um Einzelheiten ergänzte Darstellung.

Show it

Fig. 1

an embodiment of the chair according to the invention with illustration of various adjustment options

Fig. 2

an illustration of the wide range of adaptation of the chair to different body sizes,

Fig. 3

an embodiment of the locking of the synchronous mechanism according to the invention in the foremost position of the backrest, and

Fig. 4

a representation supplemented with details.

1 shows a chair with a chair base 10, to which a mechanical housing 12 is rigidly connected, which covers or supports all the parts explained below. A seat 14 is pivoted in the mechanical housing 12 at its front end about a transverse axis. A backrest 16, as is clearly shown in the figure, is not directly connected to the seat, but via telescopic support arms 18 with locking device 20 and armrests 22. The lower end of the support arms 18 is in each case on a horizontally and transversely extending first transverse axis 24 pivoted. This applies to the lower or inner part of the telescopic support arm. In contrast, the upper or outer part of the telescopic support arms 18 connected to the backrest has the armrest. The user can release the rigid connection of the two parts of the support arms 18 against each other by actuating the locking device and the upper part of the support arms guided in the manner indicated in the figure on the lower part of the Pull the support arms up and fix them in the desired position.

It can be clearly seen in Fig. 1 that with this one actuation the backrest height, the armrest height and the seat depth are adjusted simultaneously.

2 serves to illustrate the fact that the same construction can be adapted to very different body sizes in a wide range, as must be required of a large-scale product. The requirements of the relevant standards are complied with or even significantly expanded with regard to the adjustment range. It can be clearly seen that even the chair with armrest, as shown in FIG. 2, fits a table that is also adjustable in size for people, both for small and tall people and the appropriate setting under the edge of the table. It can also be clearly seen on the illustrations in FIG. 2 that the back is given good lumbar support by the backrest, but on the other hand, under this support point, there is also enough space for the buttocks for people of different sizes in the space between the backrest and seat, such as that Ergonomists demand. 2 that the backrest is clearly concave in horizontal section, so that the body of the seated person is well embedded.

It has already been mentioned above that for ergonomic reasons the chair shown is indeed equipped with a synchronous mechanism, so that when the backrest 16 is tilted backwards, the rear edge of the seat 14 also tilts downward, but this usual function of the synchronous mechanism in the foremost position of the backrest 16 is initially blocked.

Fig. 3 shows the corresponding structure in detail. The mechanical housing 12 is fastened on the chair base 10 and holds the support arms 18 of the backrest (not shown in the figure) via the first transverse axis 24 and the seat 14 via a second transverse axis 26. The first transverse axis 24 is to be arranged at a third of the total seat depth and as high as possible, that is to say close to the seat 14. The second transverse axis 26 lies in the foremost region of the seat shell 12, that is to say at the front edge of the seat.

As can be clearly seen in FIG. 3, the seat 14 is slightly inclined forward. For this purpose, it is pressed upwards by a spring, as will be explained in more detail below with reference to FIG. 4. The spring pivots the seat 14 about the second transverse axis 26 in the counterclockwise direction. This pivoting is limited by a rigid support from two levers connected in a third transverse axis 28. In the figure it can clearly be seen that the somewhat longer lever 30 is articulated at its upper end on the underside of the seat 14 and approximately vertically above the axis of the chair base 10, specifically on a dimensionally stable seat support 34 integrated in the seat 14, the front end in the mechanical housing 12 is pivotally mounted on the second transverse axis 26. The figure also shows that the lower end of the somewhat shorter lever 32 is articulated somewhat next to and in front of the axis of the chair base 10. The lever 32 is also supported with a rear-facing nose on top of the chair foot on a cushion. The figure in particular clearly shows that the two levers 30, 32 are approximately aligned with one another, so that they form a rigid support for the seat 14 in the basic position shown in FIG. 3 (backrest in front), which is further supported by the nose of the lever 32 is. In this position, the rear end of the seat 14 cannot therefore descend downward due to the support. Rather, a rigid triangular combination of seat 14, support from levers 30, 32 and mechanical housing 12 is formed. As a result, the synchronous mechanism in the foremost position of the backrest 16 is rendered ineffective.

In Fig. 3 it can be seen further that the support arms 18 on the side of the seat 14 do not end approximately in the first transverse axis 24, but instead extend beyond the first transverse axis and are connected in a rotationally locking manner here to a swivel plate 36. Fig. 3 shows an embodiment in which the pivot plate 36 is connected to the pull lever 38 in a link 40 such that the connecting line of link 40 and attachment of the lower ends of the support arms 18 on the pivot plate on the support arms 18 is perpendicular. The pivot plate 36 further carries at its rear upper end in recesses 42 a cross bar 50 as the point of engagement of a compression spring 46 (see below) which presses the backrest 16 forward. Finally, the swivel plate has three transverse holes 44 at the front, with the aid of which, according to the wishes of the user, different backrest positions can be fixed by a pin guided in the mechanical housing.

The pull lever 38 has the effect that when the user leans against the backrest 16, pushes it backwards and thus pivots the support arms 18 clockwise about the first transverse axis 24, the pivot plate 36 via the pull lever 38 on the third transverse axis 28 pulls, the angle between the levers 30, 32 is increasingly reduced and after the pivoting of the support arms 18 by a few degrees, the rigid support of the seat 14 on the mechanical housing 12 is released. Thus, the seat 14 is now released and can move through the synchronous mechanism coupled to the backrest with its rear section pivoting downward about the second transverse axis 26 when the backrest 16 is pivoted further backward. As explained, this is initially not the case in the foremost position of the backrest: unlike in the case of conventional synchronous mechanisms otherwise, no reaction on the backrest is permitted here when the user sits down on the seat 14, which is therefore not already contrary to when the user sits down desired effect dodges backwards.

Fig. 4 now shows, in addition, a compression spring 46 in the form of a mechanical coil spring, which is set axially parallel to the axis of the chair foot 10 in front of this in a corresponding receptacle 48 of the mechanism housing 12 and with its upper end on a cross bar 50 and via this on the swivel plate 36 and thus engages on the backrest 16 via the support arms 18, which is therefore pressed forward by the compression springs 46. If the user of the chair leans against the backrest 16, the compression spring designed as a mechanical coil spring is compressed accordingly between the crossbar 50 and its receptacle 48 and thus progressively increases its restoring force on the backrest in accordance with the spring constant.

In Fig. 4, a compression spring 52 in the form of a mechanical coil spring can be seen, which is inserted between a first linkage 54 on the mechanical housing 12, and a second linkage 56 on the seat support 34, which is in the region of the first transverse axis 24 on the underside of the Seat 14 is provided. The compression spring 52 thus serves to press the seat 14 upward about the second transverse axis 26, that is to say to pivot it counterclockwise in FIG. 4.

Of course, the exemplary embodiments shown in FIG. 4 for the springs 46, 52 are only two examples of numerous possibilities for spring loading of the seat 14 and backrest 16 with which these are held in the basic position. It is also clear that the compression spring 46 not only brings the backrest into the foremost position, but at the same time also ensures that in this position the rigid support from the levers 30 and 32 is again set up when this by pivoting the backrest to the rear once resolved in the manner discussed above.

It has already been explained above that the backrest height, the armrest height and the seat depth in the chair shown synchronously, that is, all three are adjusted at the same time and fixed with the locking device 20. The spring identification of the compression spring 46 for the installation of the backrest 16 is also adjusted with the aid of the usual adjusting wheel 58. The compression spring 52 is chosen appropriately.

All in all, with a simple construction, there is a chair which corresponds to the norms and the needs of ergonomics and which does not overwhelm the user due to its adjustment possibility, which chair can also remain unchanged in construction for very different body sizes of the users.

Claims (10)

1. A chair, in particular a swivel chair, with multiple adjustment for adapting to different body sizes, in which the backrest (16), which is independent of the seat (14), is held by two support arms (18), which extend either side of the seat backwards and upwards from a first transverse axis (24) beneath the seat, are adjustable in their length and can be locked in different lengths by a locking device (20), characterised in that in the inoperative position the support arms (18) form an angle of at least 45°, preferably exceeding 50° and at least approximately 52° with the horizontal,
   the first transverse axis (24) is arranged as a pivot axis for the lower end of the support arms in a height-adjustable mechanics housing (12) in front of the chair leg (10) and at a distance of one third of the seat depth from the front seat edge,
   the seat (14) is mounted at its front end in the mechanics housing (12) so as to pivot about a second transverse axis (26) and is pushed upwards by a spring (52),
   the backrest (16) is pushed forwards via a spring (46) acting upon the support arms (18), and the synchronisation coupling of the seat (14) and backrest (16) is suspended in the foremost position of the backrest by a rigid support system (30, 32) supporting the seat (14) against the seat shell (12).
2. A chair according to claim 1, characterised in that the part of the telescopically length-adjustable support arms (18) connected to the backrest (16) also supports an armrest (22).
3. A chair according to claim 1, characterised in that the springs acting upon the backrest (16) and seat (14) are mechanical springs.
4. A chair according to claim 3, characterised in that the spring (52) pushing the seat (14) upwards acts upon the seat in the vicinity of the first transverse axis (24).
5. A chair according to one of claims 1 to 4, characterised in that, in the foremost position of the backrest (16), the rigid support system of the seat (14) is effected against the seat shell (12) via two levers (30, 32), which are connected at a third transverse axis (28), upon which the lower end of the support arm (18) also acts in each case.
6. A chair according to claim 5, characterised in that the actuation of the lower end of the support arm (18) upon the third transverse axis is effected via a draw lever (38).
7. A chair according to one of claims 1 to 6, characterised in that the lower parts of the support arms (18) each support a pivot plate (36), which is secured to an extension of the support arms beyond the first transverse axis (24).
8. A chair according to claim 6 or 7, characterised in that the approximately triangular pivot plate (36) comprises an articulation site (40) at its lower rear end for the draw lever (38) and at its upper rear end comprises a recess (42) for a transverse rod (50), acting upon which is a compression spring (46), which acts upon the backrest and is arranged at least approximately axially parallel to the chair leg (10) in the mechanics housing (12).
9. A chair according to one of claims 6 to 8, characterised in that the upper of the two support levers (30) acts upon the seat (14) at least approximately in the extension of the axis of the chair leg (10).
10. A chair according to one of claims 1 to 9, characterised in that the seat (14) is inclined forwards by 3 to 4 degrees relative to the horizontal in its rigidly supported position.

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