EP0540711B1 - Working chair, especially office chair - Google Patents

Abstract

The working chair has a seat bearer (11), a seat (15) articulated on the seat bearer (11) and a squab bearer (25) with a squab (29). The squab bearer (25) has a spindle (23) on the seat bearer (11). One arm (27) is articulated on the squab (29) and the other (31) on the seat (15). The simple mechanical arrangement (20, 22, 23, 25, 35) thus formed causes the seat to be moved in one direction of rotation (47) when the squab bearer (25) is moved in the other (43). As in lying down and relaxing, the knee and hip joints thus undergo an extension. This produces a sound lordosis. The spindle (23) and the articulation axis (35) lie in a plane (36) inclined at about 70 DEG to the horizontal. Regardless whether a person is heavy or light, relatively little force on the squab (29) is needed to raise the seat (15). As the seat (15) and the squab (29) remain close together during any movement, the tendency for the shirt to be pulled out is prevented. The movement of the seat backwards and downwards when the squab is tipped backwards prevents blood congestion at the back of the knees.

Description

The invention relates to a work chair, in particular an office chair, with a seat support, a seat which can be pivoted in front on the seat support about an axis of rotation and is also approximately horizontally movable relative to the seat support, a backrest support which is articulated by means of an axis of rotation on the seat support and which has a pivot axis with the Seat is connected and a backrest which is coupled to the backrest support.

A large part of the work chairs manufactured today, as they are mainly used as office chairs, are so-called synchronous work chairs, in which the adjustment of the inclination of the backrest support simultaneously adjusts the inclination of the seat. In known synchronous work chairs, pivoting the backrest in one direction causes the seat to pivot in the same direction. The pivoting of the seat is usually only half as large as the pivoting of the backrest (US-A-2 859 799, CH-A-629 945). These work chairs have five disadvantages in particular, namely a physiologically unnatural movement when pivoting the backrest, a negative influence on the sitting posture, lack of weight neutrality, a relatively complex construction and a bulky appearance that no longer meets today's aesthetic needs. There are certain correlations between these disadvantages. Missing e.g. the weight neutrality and the spring force of a compensation device, which counteracts the force on the backrest, which causes the weight of the user, is poorly adjusted, this can also contribute to poor sitting posture, as will be explained in more detail later.

If one looks at the movement of a person's joints when standing up normally, one finds that both the knee joints and the hip joints are stretched or, as is said in medicine, an extension. The same applies to lying down and relaxing.

Conversely, flexion occurs in both joints when sitting down. In contrast to the natural sequence of movements, for example in the work chair according to CH-A-629 945, when the backrest is pivoted backwards, the rear part of the seat is moved downwards, the pivoting of the seat plate being only about half as large as that of the backrest. This leads to a physiologically unnatural movement. So there is an extension of the hip joints, but a flexion of the knee joints.

In order to pivot backwards in a work chair in accordance with CH-A-629 945, the user presses the upper body against the backrest and supports himself firmly on the floor with his legs. There is a risk that the user will slide forward a little, especially if a relatively large amount of force has to be used to swivel it. Since the front edge of the seat also moves upward, blood congestion can occur in the area of the knee joints.

A lever is sufficient to raise the backrest. This releases the springs that were tensioned backwards when swiveling. The backrest and seat then return to the original position or to an intermediate position desired by the user. If the user slipped a little when swiveling backwards, his pelvis is now in a sloping position to the rear. He has a bad posture that can easily lead to back pain.

In the case of CH-A-629 945, the backrest is pivoted backwards against the force of a gas spring and a compression spring, the prestressing of the compression spring being changeable by adjusting nuts. In practice, however, this does not allow a satisfactory adjustment to the weight of a particular user. A preload is therefore usually set which is adapted approximately to the weight of the average user. If a light person now uses the chair, they have difficulty to move the backrest backwards. There is a great risk that it will slide forward on the seat. In the opposite case, if a heavy person uses the chair, they find it uncomfortable when adjusting the backrest if it moves backwards with practically no noticeable resistance due to the heavy weight of the person.

The energy used to swivel the backrest is largely stored in the springs in the work chair of CH-A-629 945 and is released when a locking device is released in order to move the backrest and upper body of the chair user forward again. If the user leaves the chair without moving the backrest forward and is e.g. the locking device is released by cleaning personnel, the backrest swings forward with great force and speed. This poses a significant risk of injury.

US-A-4,834,454 describes a chair in which a seat on the front of the seat support is pivotable about an axis of rotation. An L-shaped backrest support can be pivoted about a pivot axis arranged on the seat support. The L-shaped backrest support is connected to the seat at the end of the horizontal bar of the L by means of a pivot axis. If the backrest is pivoted backwards, the backrest support, which is firmly connected to the backrest, lifts the rear part of the seat. At the same time, the seat is pushed back a little. It proves to be disadvantageous that at the beginning of a swiveling movement of the backrest, a very large force is required to lift the seat which is loaded by the user, because in the first part of the swiveling movement the articulation axis at the end of the horizontal bar has to be moved steeply upwards . Another disadvantage is that a heavy user has to use considerably more force than a light user. It is also particularly unfavorable that the distance between the seat and the backrest increases considerably when the backrest swivels backwards. This leads to the unpleasant shirt pulling effect.

It is therefore an object of the present invention to at least partially avoid the disadvantages of previously known work chairs. A work chair with a synchronous mechanism is to be created in which the user's body performs physiologically natural movements. The movement sequence should also lead to a good sitting posture. The construction of the chair should be simple. But it should also meet the highest possible aesthetic requirements that are placed on work chairs, especially office chairs.

Based on the prior art according to US-A-4 834 454, this is achieved according to the invention in a chair according to claim 1. In such a chair, pivoting the backrest support in one direction causes the seat to pivot in the opposite direction. If, for example, the backrest support is pivoted backwards, the rear part of the seat moves upward about a pivot point in the front region of the seat. The body takes part in a natural sequence of movements by stretching, as in normal standing, for both the hip joint and the knee joint. In addition to this general sequence of movements, details of the sequence of movements are also of particular importance. The high angle of inclination defined in claim 1 has the consequence that the seat is also moved relatively far to the rear when the backrest is pivoted. This further promotes the extension of the knee joint and prevents blood build-up in the knee joints. The high angle of inclination also means that a relatively small force is required to initiate the pivoting of the backrest to the rear. The user therefore finds this movement convenient. The good exercise sequence created in this way encourages active sitting. Active sitting promotes blood flow to organs and limbs and contributes to the general well-being of the chair user. Premature fatigue, which is typical for passive sitting, is prevented. Partial weight compensation through force compensation is also important. A force compensation is done by the force that is exerted on the backrest acts, counteracts the force caused by the weight of the user on the seat. Thanks to this force compensation, there is no need for weight adjustment for light and heavy people.

The invention also has the advantage of a particularly simple construction, which also allows an aesthetically particularly appealing design of the work chair. In practice, only one lever is required, namely the backrest support.

The angle of inclination of the plane in which the axis of rotation of the backrest support and the articulation axis of the backrest support are located on the seat is advantageously in the range from 60 to 70 degrees. Tests have shown that the chair is perceived by the user as particularly comfortable at such an angle of inclination. With this angle of inclination there is also a movement sequence of the seat and backrest which does not lead to a shirt pull-out effect.

The distance between the axis of rotation and the articulation axis is advantageously approximately 80 to 120 mm, preferably approximately 100 mm. This results in favorable conditions for a weight balance and an optimal way for backward movement of the seat when the backrest is pivoted backwards.

The backrest is expediently articulated to the backrest support. This enables a favorable movement of the backrest. In particular, if the backrest is designed as a pendulum backrest, the lordosis, i.e. the physiological curvature of the spine of the chair user to the front, intensified.

Experiments have shown that it is expedient to arrange the articulation point of the backrest behind the axis of rotation at an angle of 10 to 20 degrees, preferably 15 degrees, to the vertical leading through the axis of rotation.

The spring element, which strives to move the backrest and the seat forward, advantageously has a relatively steep characteristic, so that the spring force increases with increasing inclination of the backrest and thus counteracts the force on the backrest caused by the weight of the upper body of the chair user.

The articulation axis is expediently located in the region of the rear half of the seat. This arrangement results in favorable conditions for weight compensation.

The front of the seat can be stored in different ways. So it is possible that the front seat is connected to the seat support by means of a flexible connecting piece. An expedient embodiment provides a connection via a support lever. This support lever is advantageously arranged approximately vertically in the front position of the backrest. The result of this is that when the backrest is pivoted backwards, the front part of the seat is slightly lowered. This slightly reduces the pressure on the body in the area of the hollow of the knee, which contributes to the desired relaxation of the body and promotes blood circulation.

However, it is also possible for the seat to be connected at the front to the seat support by means of a sliding piece running in a guide. This results in a simple construction.

The spring element is advantageously an elastomer block. Elastomer blocks, which are known under the name "cell volcano", also have movement-damping properties. This prevents the backrest from rapidly advancing. An elastomer block or a coil spring are advantageous because, in contrast to a gas spring, they have a relatively steep spring characteristic. The restoring force exerted by the elastomer block or the mechanical spring at the start of a backward movement of the backrest is therefore low. Thanks to the mechanism according to the invention, there is extensive force compensation in this area between the force acting on the seat and the force acting on the backrest.

Towards the end of the backward movement of the backrest, however, the force acting on the seat is far from sufficient to compensate for the force acting on the backrest. For this reason, the high restoring force of the elastomer block is of great advantage in this area. The user feels the chair very comfortably and is thus encouraged to sit actively.

Various options remain open to the designer for the arrangement of the spring element. For example, engage the spring element directly on the backrest. However, it is particularly advantageous if the spring element is arranged practically parallel to the seat and acts on it. This allows the mechanism under the seat to be made very compact, which is desirable for aesthetic reasons.

The seat and backrest can be made from a single flexible part, e.g. Plastic part. It is also possible that the seat shell and backrest shell are made from a single part, e.g. Plastic part exist, which has an articulated section. Such constructions are made possible by the arrangement according to the invention of the axis of rotation of the backrest support and of the articulation axis which connects the backrest support to the seat, because in this arrangement an undesired movement between the seat and backrest, which would lead to a shirt pull-out effect, is avoided.

A clamping device, for example a lamella clamping device, advantageously serves to lock the seat and the backrest in the desired position. Since the seat in the design of the work chair according to the invention has a relatively large travel path when the backrest moves, a locking device acting on the seat only has to absorb relatively small forces, so that a clamping device can be used for locking instead of the usual gas spring. Such clamping devices are cheap to manufacture and, in contrast to gas springs, also do not have any disposal problems.

The seat is advantageously strongly shaped, i.e. with depressions corresponding to the contours of the human body. This counteracts the risk of slipping even when the seat is inclined relatively strongly.

The arrangement of the axis of rotation, the articulation axis and the articulation point is expediently such that, in the normal position, the angle of inclination of the seat to the rear is approximately 3 degrees and includes an angle of approximately 103 degrees with the plane in which the articulation axis and the articulation point of the backrest lie , and that when the backrest support is pivoted about 34 degrees backward, the seat is pivoted upward about 5 degrees. This configuration has proven to be very practical ergonomically.

Fig. 1

ein erstes Ausführungsbeispiel eines Arbeitsstuhl in der normalen Sitzstellung,

Fig. 2

den Arbeitsstuhl von Fig. 1 in der Entspannungsstellung, in welcher die Rückenlehne nach hinten bewegt wurde,

Fig. 3

ein zweites Ausführungsbeispiel eines Arbeitsstuhls in der normalen Sitzstellung,

Fig. 3a

eine Variante für den Rückenlehnenträger,

Fig. 4

den Arbeitsstuhl von Fig. 3 in der Entspannungsstellung,

Fig. 5

ein drittes Ausführungsbeispiel eines Arbeitsstuhls in der normalen Sitzstellung,

Fig. 6

den Arbeitsstuhl von Fig. 5 in der Entspannungsstellung.

Embodiments of the invention will now be described with reference to the drawing. It shows:

Fig. 1

a first embodiment of a work chair in the normal sitting position,

Fig. 2

1 in the relaxation position, in which the backrest has been moved backwards,

Fig. 3

a second embodiment of a work chair in the normal sitting position,

Fig. 3a

a variant for the backrest support,

Fig. 4

3 in the relaxation position,

Fig. 5

a third embodiment of a work chair in the normal sitting position,

Fig. 6

5 in the relaxation position.

In the embodiment of FIGS. 1 and 2, the seat support 11 is carried in the usual manner by a base with a standpipe 13 and a height lift. Of these parts, only the standpipe 13 is indicated in the drawing. The seat 15 is advantageously strongly shaped, that is to say has a recess 16 at the rear, which counteracts slipping forward. Padding 18 can also be provided in the usual way. The backrest 29 can also have padding 30. The seat 15 is in the region of its front end on the seat support 11 e.g. supported by a support lever 17. The support lever 17 has an articulated connection 19 with the seat support 11 and an articulated connection 21 with the seat 15. The support of the seat 15 on the seat support 11 could also be carried out, for example, by means of a flexible connecting piece made of elastomeric material. The chair also has a backrest support 25 which is articulated to the seat support 11 with an axis of rotation 23. This backrest support 25 is a two-armed lever. One arm 27 of the two-armed lever is coupled to the backrest 29, which is designed as a pendulum backrest. The other arm 31 of the two-armed lever 25 is coupled to the seat 15. The arm 27 is coupled approximately in the middle or somewhat below the center of the backrest 29, e.g. by means of a joint 33. The other arm 31 is coupled in the area of the rear half of the seat 15 via the articulation axis 35. There is a distance of about half the seat length or slightly more, e.g. two thirds of the seat length.

The position of the articulation axis 35 with respect to the axis of rotation 23 is of particular importance. The articulation axis 35 is located at a location which lies in front of and above the axis of rotation 23. It is important that in the normal sitting position, ie with the backrest 29 in a practically vertical position, the angle of inclination of the plane 36 in which the two axes 23, 35 lie is in the range from 45 to 80 degrees, advantageously 60 to 70 degrees. From this area, when the backrest 29 is pivoted backwards, the articulation axis 35 moves in the direction of the arrow 45. This requires a relatively small force necessary. The seat 15 is also moved relatively strongly to the rear. The distance between the axes 23 and 35 is approximately 80 to 120 mm, advantageously approximately 100 mm. This results in favorable conditions for weight compensation.

On the two-armed lever 25 there is a nose 37, to which a spring element 39 engages. This spring element 39 tends to move the backrest 29 forward, i.e. to put them back in their normal sitting position. The spring element 39 is advantageously a coil spring, e.g. a compression spring which is guided by a telescopic device 41. However, an elastomer block, e.g. from "Zellvulkolan", find use.

A locking device 42 with an actuating lever 44 is shown schematically. A simple clamping device, e.g. Slat clamping device, serve. Because, as mentioned in the introduction, there is a weight balance and the seat has a relatively long travel path, only relatively small forces have to be absorbed when locking, so that a clamping device is sufficient.

Comparing the positions of the chair of FIGS. 1 and 2, it can be seen that a force on the backrest 29 in the direction of arrow 43 causes the seat 15 to move back and up in the direction of arrow 45. The seat 15 rotates about the hinge 21 in the direction of the arrow 47 so that the front edge of the seat is lowered. The torques exerted on the arms 27, 31 counteract each other so that relatively little energy is used by the chair user - be it light or heavy - must be used to move from the position of Fig. 1 to the position of Fig. 2.

FIGS. 3 and 4 clearly show that the backrest follows the upper body faithfully and that the shirt is therefore not removed.

In summary, it can be stated that the advantages achieved by the mechanics described are considerable for the users, namely more pleasant because of natural movement, comfortable sitting for light and heavy users thanks to force compensation between the seat and backrest, prevention of blood congestion at the back of the knee thanks to the ergonomic movement the fit, preventing the shirt pull-out effect and especially good lordosis.

The exemplary embodiment according to FIGS. 3 and 4 differs from the previously described exemplary embodiment essentially by the other support of the seat 15 on the seat support 11 and the different arrangement of the spring 39. Thus, an inclined guide 20, e.g. Elongated hole provided in which a slider can slide. This can e.g. be a rod 22 which is supported by the tabs 24 of the seat 15. The spring element 39, e.g. an elastomer block ("cell volcano") is arranged practically parallel to the seat 15 and is supported at one end at 26 on the seat support 11 in order to act on the seat 15 at the other end. The spring element 39 transmits its force via the rod 22 and the tabs 24 to the seat 15 and strives to move the seat 15 forward into the position of FIG. 3.

The backrest support 25 can be given various shapes. A possible variant is shown in Fig. 3a. The possibility of connecting the axes 23, 35 and 33 in different ways gives the designer many options for a pleasant design of the work chair. For example, a backrest support 25 can be provided on each side, the two backrest supports being connected to one another by the hinge axis 23. An extension 46 can also serve as an armrest (FIG. 3a).

The exemplary embodiment according to FIGS. 5 and 6 differs from that of FIGS. 3 and 4 essentially in that the rear part of the seat 15 and the lower part Part of the backrest (29 to 28) are hinged together. The seat shell and backrest shell can thus consist of a single elastic part, for example a plastic part, or a single part which has an articulated section 28.

Claims (21)

1. A work chair, more particularly an office chair, comprising: a seat frame (11), a seat (15) pivotable forwards on the seat frame around a first pivot (21) and also movable substantially horizontally relatively to the seat frame (11); a back frame (25) in form of a two-armed lever articulated by way of a second pivot (23) to the seat frame (11) and having one arm (31) connected by way of a third pivot (35) to the seat (15); and a back (29) coupled with the back frame (25), the third pivot (35) being disposed before and higher than the second pivot (23), characterised in that the angle of inclination of the plane (36) in which the third pivot (35) and second pivot (23) are disposed is in the region from 45° to 80° to the horizontal when the work chair is in its forward position.
2. A work chair according to claim 1, characterised in that the angle of inclination is in the region from 60° to 70°.
3. A work chair according to claim 1 or 2, characterised in that the distance between the second pivot (23) and the third pivot (35) is approximately from 80 mm to 120 mm, preferably 100 mm.
4. A work chair according to any one of claims 1 to 3, characterised in that the back (29) is pivotally connected to the back frame (25) by way of an articulation (33).
5. A work chair according to any of claims 1 to 4, characterised in that the articulation (33) of the chair back (29) is disposed behind the second pivot (23) at an angle of from 10° to 20°, preferably 15°, to the vertical through the second pivot (23).
6. A work chair according to any of claims 1 to 5, characterised in that a spring element (39) tending to move the back (29) forwards is provided.
7. A work chair according to any of claims 1 to 6, characterised in that the third pivot (35) is disposed near the rear half of the seat (15).
8. A work chair according to any of claims 1 to 7, characterised in that the back (29) is a rocking back.
9. A work chair according to any of claims 1 to 8, characterised in that the seat (15) is connected at the front to the seat frame (11) by means of a flexible connecting member.
10. A work chair according to any of claims 1 to 8, characterised in that the seat (15) is connected at the front to the seat frame (11) by way of a support lever (17).
11. A work chair according to claim 10, characterised in that in the normal position of the back (29) the support lever (17) is disposed substantially vertically.
12. A work chair according to any of claims 1 to 11, characterised in that the seat (15) is connected at the front to the seat frame (11) by means of a slide block (22) moving in a guide (20).
13. A work chair according to any of claims 6 to 12, characterised in that the spring element (39) is an elastomer block.
14. A work chair according to any of claims 6 - 13, characterised in that the spring element (39) is a helical spring.
15. A work chair according to claim 10, characterized in that the spring element (39) acts on the back frame (25).
16. A work chair according to claim 10, characterized in that the spring element (39) is arranged substantially parallel to the seat (15) and acts thereon.
17. A work chair according to any of claims 1 to 16, characterised in that the seat (15) and the back (29) are made of a single flexurally resilient part, for example, a plastics part.
18. A work chair according to any of claims 1 to 16, characterised in that the seat (15) and back (29) are made of a single part, for example, a plastics part, having an articulation-like part (28).
19. A work chair according to any of claims 1 - 18, characterized in that clamping means, for example, plate clamping means, are provided to lock the seat (15) and the back frame (25) in the required position.
20. A work chair according to any of claim 1 to 19, characterised in that the seat (15) is markedly concave.
21. A work chair according to any of claims 4 to 20, characterised in that the second pivot (23), third pivot (35) and articulation (33) are so arranged that in the normal position the angle of inclination of the seat (15) is approximately 3° to the rear and includes an angle of approximately 103° with the plane in which the third pivot (35) and the articulation of the back (29) are disposed, and in response to an approximately 34° pivoting of the back frame (25) the seat pivots upwardly by about 5°.

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