EP0049310B1 - Working chair - Google Patents

Description

The invention relates to a piece of work seating, with a backrest hingedly connected to a seat and with a base frame, on which the seat is supported in its front region via a joint and the backrest is supported by a lumbar support arm, the support lever being approximately below the The center of the seat is articulated on the underframe and, in the basic position, the seat is oriented essentially horizontally and the backrest is oriented vertically on the middle and is returned to the basic position by a return spring force.

Seats in which the seat inclination and the back inclination can be changed in a certain ratio to one another are known in various embodiments. In the unloaded state, the seating furniture, when the seat is generally horizontal, has an angle of 90 ° between the seat and the backrest, which is maintained as long as the user in the working position essentially only loads the seat surface. If the user wants to lean back into a rest position, the known seat furniture tilts - generally only after releasing a lock - the seat surface slightly downwards by a small angle at the rear end and swivels the backrest by a two to three times larger Angle backwards, with angles of up to 130 ° C between the seat and back surface for the rest position. Such seating furniture with so-called "synchronous" seat and back adjustment already provides an ergonomically quite favorable adaptation of the seating furniture support surfaces to the respective posture of the user, but this applies only to a limited extent in the area of the lower lumbar vertebrae if, for example, the arrangement according to DE -OS 2 332 596 links the rear seat edge directly or via low pedestals to the adjacent backrest. It has therefore already been provided, e.g. in the case of the seating furniture according to DE-GM 7 721 954 and 7 815 561, to divide the seat into a front and into a rear partial surface which is connected to the latter in an articulated manner. In this case there are three inclinable body support surfaces including the backrest, but here the adaptation to the respective posture is only achieved by a considerable additional construction effort.

From CH-A-541 946 a recliner with a one-piece seat-back shell is known, which consists of two rigid zones that are articulated to each other by a flexible central zone. There, in the basic position, the backrest is inclined backwards and held on armrests by leather straps. When the user straightens up, the shell there is pressed deep down and the previously horizontal seat is pivoted into a very inclined position. The well-known armchair cannot be used as work seating.

The invention has for its object to provide a work seating with synchronous seat and backrest adjustment that - while avoiding complex mechanics - an effective support also in the area of the lumbar vertebrae and in the rest position an even from the hollow of the knee to the shoulder blades Ensuring the support surfaces fit the user's body.

This object is achieved according to the invention in that the seat and the backrest merge into one another via an arcuate, bendable intermediate part and in that the connecting line of the two articulation points of the support lever in the basic position at an angle between 0 to 25 °, preferably between 15 to 25 ° , is inclined to the vertical.

The steep position of the support lever in the basic position ensures that when changing from an upright work posture to a reclined posture, the backrest is first moved considerably more horizontally backwards than downwards. In connection with the widening and quasi-rolling intermediate part between the seat and backrest, this provides a uniform and extensive support of the entire body during the transition to the rest position. Due to the initial preference of the backrest movement over the backrest movement provided for in the invention, the anatomy of the human body is taken into account in such a way that when changing over to a rest position, the upper body not only swings backwards like a lever around a joint, but at the same time the body also swings over the pelvis of the pelvis rolls a little to the rear and the upper body also collapses somewhat as the at least lower back lumbar vertebrae are moved back. The seating furniture according to the invention is adapted to these body movements and proves to be a very tight, comfortable support.

According to a preferred embodiment of the invention it can be provided that the backrest is convexly curved in the vertical longitudinal section towards the seat and that the lower half of the backrest is inclined forward in the basic position. This enables a very good support of the lower lumbar vertebrae and the cross area when sitting upright, in which the lower part of the spine is also slightly inclined forward. When changing over the vertical to a reclined rest position, the seat according to the invention performs a clear evasive movement to the rear, so that the user's pelvis can roll and the spine can pass into a more extended and reclined position.

According to further features of the invention it can be provided that the distance between the two articulation points of the support lever is approximately twice as large as the distance between the lower articulation point of the support lever and the front seat articulation point and that these articulation points define an acute-angled triangle in the basic position. The constellation of these articulation points results in a coordinated behavior of the seat and backrest inclinations in the different seating positions of the human body. The flexible intermediate part proves to be of great advantage in the invention, since it makes mechanical sliding joints, toggle levers or similar complex mechanics superfluous.

According to the invention, it can further be provided that the seat linkage is about a quarter of the seat depth behind the front edge of the seat and that the front third of the seat is bent downward to a greater extent than the front edge of the seat is pivoted up when the seating furniture is pivoted back. These measures also ensure favorable support and freedom in the area of the hollow of the knee in all seating positions.

According to further features of the invention, the lower articulation point of the support lever can be offset from the center of the seat by about 10% of the seat depth, which among other things results in a great stability of the seating furniture against tipping.

Furthermore, the backrest can be concavely curved in cross section to the seat and can be provided with a strongly drawn lumbar bulge, on which the upper articulation point of the support lever is arranged. On the one hand, these measures directly improve the support and, on the other hand, enable the support levers to be set very steeply without impairing the appearance of the seating furniture.

According to a preferred embodiment of the invention, the seat and the backrest consist of a one-piece plastic shell. In this case, the shell can have semi-cylindrical bearings with a snap edge at the front seat pivot point for receiving a horizontal bearing axis attached to the base frame.

The seating furniture can be manufactured as a chair or as an armchair with armrests. In the latter case, elastic armrests are provided, which are attached to the articulation points of the seat and backrest on the seating furniture. With appropriate dimensions, these armrests can provide the entire return spring force for the seating furniture alone. Instead of or in addition to the springback via the armrests, it can also be provided that the support lever is loaded directly or indirectly at its lower end by a return spring. The seating furniture can be equipped with a device for adjusting the bias of the return spring in order to be able to adapt to the weight and size of the user.

Furthermore, the chair can be equipped with a device for locking the support lever at least in the basic sitting position.

According to the invention, either a torsion axis as the lower linkage of the support lever or helical or leaf spring or a gas spring can be provided as the return spring, which act on a cam projecting radially from a lower bearing shaft.

Finally, according to the invention, as an alternative to a one-piece plastic shell, it can also be provided that the seat and backrest each have separate frames which merge into one another via elastic intermediate pieces.

• Figur 1 ein erstes Ausführungsbeispiel eines als Arbeitsstuhl ausgebildeten Sitzmöbels nach der Erfindung, in Seitenansicht und Grundstellung,
• Figur 2 den Arbeitsstuhl nach Figur 1 in zurückgeschwenkter Ruhestellung,
• Figur 3 ein zweites Ausführungsbeispiel eines Sitzmöbels, welches mit elastischen Armlehnen versehen ist,
• Figur 4 ein drittes Ausführungsbeispiel eines Sitzmöbels in vereinfachter perspektivischer Darstellung
• Figur 5 in Seitenansicht die Sitz-Rückenlehnenschale des Sitzmöbels,
• Figur 6 in einem Detailschnitt ein Ausführungsbeispiel für die Ausbildung einer Rückstellfeder für das Sitzmöbel,
• Figur 7 in einem Detailschnitt eine zweite Ausführungsform einer Rückstellfederung für den Sitz,
• Figur 8 in einem Detailschnitt eine dritte Ausführungsform der Rückfederung für das Sitzmöbel,
• Figur 9 eine Draufsicht zu Figur 8,
• Figur 10 eine Detaildraufsicht gemäss Pfeil X in Figur 8,
• Figur 11 einen Schnitt gemäss der Linie XI-XI in Figur 10 und
• Figur 12 und 13 je eine Skizze zur Veranschaulichung der Körperbewegungen beim Übergang von einer aufrechten Sitzhaltung zu einer zurückgeneigten Haltung.

The invention is explained in more detail below with reference to several exemplary embodiments shown in the drawing, in which:

• FIG. 1 shows a first exemplary embodiment of a piece of seating furniture designed as a work chair according to the invention, in side view and basic position,
• FIG. 2 the work chair according to FIG. 1 in the rest position swung back,
• FIG. 3 shows a second exemplary embodiment of a piece of seating furniture which is provided with elastic armrests,
• Figure 4 shows a third embodiment of a piece of seating furniture in a simplified perspective view
• 5 is a side view of the seat backrest shell of the seating furniture,
• FIG. 6 shows a detail section of an exemplary embodiment for the formation of a return spring for the seating furniture,
• FIG. 7 in a detail section a second embodiment of a return spring for the seat,
• 8 shows a detail section of a third embodiment of the springback for the seating furniture,
• FIG. 9 shows a top view of FIG. 8,
• FIG. 10 shows a detailed top view according to arrow X in FIG. 8,
• Figure 11 is a section along the line XI-XI in Figure 10 and
• Figures 12 and 13 each a sketch to illustrate the body movements during the transition from an upright sitting posture to a reclined posture.

1 and 2 has a column-shaped base frame 1, from which at the upper end, approximately below the middle of the seat, a flat, broad support arm 2 protrudes obliquely upwards, which carries a horizontal axis 3 'at its front end, on which the seat 4 is articulated in its front area. At the top is in the column of the base frame 1, approx. 10% of the seat depth T - offset to the rear with respect to the column axis, a horizontal shaft 5 'is mounted, at the two ends of which a support lever 6 is rigidly attached, the other end of which is approximately at lumbar height on a backrest 7 of the seating at position 8 are articulated at lumbar height. The articulation points 3, 5 and 8 form an acute-angled triangle, the connecting line V between the articulation points 5 and 8 being approximately twice as long as the distance between the articulation points 3 and 5 on the base frame. The connecting line V between the articulation points 5 and 8 of the support lever 6 is inclined at an angle a of approximately 20 ° with respect to the vertical. The basic position 1 is fixed to the front by a stop (not shown).

In the embodiment according to FIGS. 1 and 2, the seat 4 and the backrest 7 consist of a one-piece plastic shell and are connected to one another in a virtually articulated manner by a middle or intermediate part 9 which is almost flat in cross section. The radius of curvature of this flexible intermediate part 9 is approximately 10 cm in the basic position. The backrest 7 is convex towards the seat - seen in the vertical longitudinal section - and the lower half 10 of the backrest 7 is inclined forward in the basic position. The backrest 7 is also curved in a horizontal cross-section concave to the seat and provided with a strongly drawn lumbar bulge 11, on each of which the upper articulation points of the two support levers 6 are designed in the form of bearing eyes 12 (FIG. 5).

The front seat pivot point 3 lies about a quarter of the seat depth T behind the front edge 13 of the seat, and the front third of the seat is bent downward. Semi-cylindrical bearings 14 with snap edges 15 for receiving the ends of the bearing axis 3 'are formed on the underside of the seat.

In the working position according to FIG. 1, the seat 4 is essentially horizontal and the backrest 7 is aligned vertically on the middle, as indicated by the dash-dotted lines S and R in FIG. 1. When leaning back, the entire seat pivots on the one hand around its front articulation point 3 by a small angle β, but the relatively steep support lever 6 of the backrest 7 additionally forces a pivoting movement by an angle y backwards. A considered point P lying at the lumbar level thus executes a movement component X in the horizontal direction, which is considerably larger than its movement component Y in the vertical direction, when moving into the position P 'of the rest position. This corresponds to the natural movement of the body (see FIGS. 12 and 13) during the transition from an upright sitting posture according to FIG. 12 to a reclined sitting position according to FIG. 13, since in addition to the pivoting of the body, there is also rolling over the seat bumps 16 and this Spine 17 stretches a little more. In the preferred embodiment, the transition area 9 between seat 4 and backrest 7 is bulged out to the rear to such an extent that, when sitting in a straight position, a free space 18 usually remains, into which the pelvis inserts itself during the transition into the inclined position.

Fig. 3 shows the chair according to FIGS. 1 and 2 in a further development as an armchair with elastically resilient armrests 19 which are fastened to the seat or to the backrest in the region of the articulation points 3 and 8.

In the embodiment according to FIG. 4, in which the upholstery or covering 20 is indicated by dash-dotted lines, the seat and backrest each comprise an approximately U-shaped support tube frame 21, 22, in the open ends of which bent spring steel pieces 23 are inserted with their ends. The bent spring steel pieces 23 in turn form the flexurally elastic zone analogous to the intermediate part 9 of the exemplary embodiment according to FIG. 1, and they are also strongly curved in accordance with the seat shell representations according to FIGS. 5 and 13. In this exemplary embodiment, the two support arms 6 and 6 'are each about a torsion axis 24, 24 'mounted in the base, which provide the springback force. The torsion axes are taken from a cross member 25 to which they are rigidly attached in the center, see also FIG. 6.

6 illustrates a device with which the clamped middle ends of the torsion axes 24/24 'can be pretensioned. A lever 26, which is rigidly connected to the torsion axes 24/24 'and projects into the support arm 2, receives a knurled screw 27 in a threaded bore located at its front end. This knurled screw 27 is supported at its end on the wall of the U-shaped support arm 2. By turning the knurled screw 27, the lever 26 is pivoted about the center of the torsion axis, so that the torsion axes 24/24 'are rotated into a prestressed position.

For the seating furniture according to the embodiments of FIGS. 1 to 3, return springs are preferably provided in the form of cylindrical coil springs or a leaf spring assembly, which are arranged within the support arm 2. The restoring spring designed as a leaf spring assembly 28 according to FIG. 7 can likewise be used to set the desired restoring force. The leaf spring assembly 28 lies at one end between an L-shaped receptacle 29 arranged on the support arm 2 and an abutment 30 screwed onto the support arm 2. Its free end lies on the foot end of a cap screw 31 which passes through a cam 32 which is held by a clamping ring 33 is rotatably connected to the horizontal shaft 5 '. By screwing in the screw 31, the leaf spring assembly 28 is bent around its abutment 30 and is thus preloaded.

In the embodiment according to FIGS. 8 to 11, the restoring force is exerted on the backrest 7 by two helical springs 34 arranged parallel next to one another. The helical springs 34 enclose bolts 35, which at one end pass through a movable abutment plate 36, which forms a support surface for the helical springs 34. The second support surface of the coil springs 34 forms a pressure plate 38 which is firmly connected to the bolts 35. The bolts are each rotatably connected to a cam 39 of the horizontal shaft 5 'via a fork head 37.

The bolts 35 are mounted in corresponding bores in the rigid support plate 40 and also protrude beyond the support plate 40 in the rest position. The support plate 40 carries on an L-shaped bend 41 a bearing piece 43 provided with an inclined plane 42, on the inclined plane 42 of which a slide piece 44 is seated a threaded hole directed onto the inclined plane is provided. By means of a knurled head screw 45, which passes through the angled portion 41 and the bearing piece 43 with great play and is screwed into the sliding piece 44, the abutment plate 36 can be moved together with the sliding piece and thus the spring preload can be adjusted.

Claims (14)

1. Article of sitting furniture for working purposes with a back (7) articulated to a seat (4) and with an underframe (1) on which the seat (4) is supported in its forward zone via a joint (3) and the back (7) is supported by a supporting lever (6) articulated at hip level, wherein the supporting lever (6) is articulated approximately below the seat center at the underframe (1) and whereby, in the basic position, the seat (4) is directed generally horizontally and the back (7) is directed on an average vertically and whereby the seat (4) and the back (7) are put back into the basic position by a resilient restoring force, characterized in that the seat (4) and the back (7) merge by way of an arcuate intermediate section (9) which can be flexed so that the arc becomes wider; and that the connecting line (V) of the two points of articulation (5, 8) of the supporting lever (6) is inclined, in the basic position, at an angle of between 0° and 25°, preferably between 15° and 25°, with respect to the vertical.

2. Article of sitting furniture according to claim 1, characterized in that the back (7) is curved convexly toward the seat (4) as seen in a vertical longitudinal section; and that the lower half (10) of the back is inclined forwardly in the basic position.

3. Article of sitting furniture according to claims 1 and 2, characterized in that-as seen in a lateral view-the spacing between the two points of articulation (5, 8) of the supporting lever (6) is about twice as large as the spacing between the lower point of articulation (5) of the supporting lever (6) and the frontal point of articulation (3) of the seat; and that these points of articulation in the basic position define an acute triangle.

4. Article of sitting furniture according to claims 1-3, characterized in that the seat articulation point (3) lies behind the forward edge (13) of the seat by about one-fourth of the seat depth (T); and that the forward third of the seat is bent downwardly to a greater extent than the seat front edge is pivoted upwardly during the backward swinging of the seat.

5. Article of sitting furniture according to claims 1-4, characterized in that the lower articulation point (5) of the supporting lever (6) is offset toward the rear from the seat center approximately by 10% of the seat depth (T).

6. Article of sitting furniture according to claims 1-5, characterized in that the back (7) as seen in a horizontal section is curved concavely with respect to the seat (4) and is provided with a strongly forwardly curved bulge (11) for supporting the small of the back, to which the upper articulation points (8) of the supporting levers (6) are mounted.

7. Article of sitting furniture according to claims 1-6, characterized in that the seat (4) and the back (7) consist of a one-piece synthetic resin shell.

8. Article of sitting furniture according to claims 1-7, characterized in that semicylindrical bearings (14) with a snap rim (15) for receiving a horizontal bearing axle (3') attached to the underframe (1) are molded to the shell at the forward seat articulation point (3).

9. Article of sitting furniture according to claims 1-8, characterized by elastic armrests (19) attached to the points of articulation (3, 8) of seat (4) and back (7) at the article of sitting furniture.

10. Article of sitting furniture according to one or more of the preceding claims, characterized in that the seat and the back each exhibit separate frames (21, 22) which pass over into each other by way of elastic connecting members (23).

11. Article of sitting furniture according to one or more of the preceding claims, characterized in that the supporting lever (6) is stressed directly or indirectly at its lower end by a restoring spring.

12. Article of sitting furniture according to claim 11, characterized by a device for adjusting the bias of the restoring spring.

13. Article of sitting furniture according to claims 11 and 12, characterized by a device for locking the supporting lever (6) at least in the basic sitting position.

14. Article of sitting furniture according to claims 11-13, characterized in that the restoring spring is either a torsion rod (24) as the bottom articulation for the supporting levers (6) or coil springs (34) or leaf springs (29) or a pneumatic spring, all of which are effective on a cam projecting radially from a lower bearing shaft (5') of the supporting levers (6).

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