Mechanism for an office chair

Abstract

A mechanism for an office chair allows a pivoting resistance of a backrest support to be altered. The mechanism for the office chair, in which a small adjustment travel is sufficient in order to realize a large adjustment range of the pivoting resistance of the backrest, has an actuating element connected to the backrest support with a supporting and/or guide track for a functional element. The functional element brings about a change in the spring tension of a spring element during pivoting of the backrest support.

Claims

1. A mechanism for an office chair, the mechanism comprising: a spring mechanism having at least one spring element, said spring mechanism being operatively connected to a backrest support of the office chair and configured to determine a pivoting resistance of the backrest support during a pivoting from a starting position into a pivoted position; a movable functional element operatively connected to said spring mechanism; a movable actuating element operatively connected to said functional element and being disposed so that a position of said actuating element is altered during the pivoting of the backrest support, said actuating element having a track for said functional element, and wherein a position of said functional element on said track is altered during a change in the position of said actuating element during the pivoting of the backrest support; and a movable control arm for a coupling connection of said functional element to a further structural element of the mechanism, said control arm being configured to determine a type of change in the position of said functional element on said track during the pivoting of the backrest support, said control arm being connected to said further structural element of the mechanism in a variable location.

2. The mechanism according to claim 1, wherein said actuating element is firmly connected to the backrest support.

3. The mechanism according to claim 1, wherein said functional element is a rolling or sliding body mounted in a variable position and said functional element is acted upon directly by said actuating element.

4. The mechanism according to claim 3, wherein said functional element is a cylindrical pin.

5. The mechanism according to claim 3, wherein said functional element has at least one bearing.

6. The mechanism according to claim 5, wherein said at least one bearing is a roller bearing.

7. The mechanism according to claim 1, wherein said control arm is supported on said further structural element of the mechanism.

8. The mechanism according to claim 1, wherein the location of the connection of said control arm to said further structural element of the mechanism is variable while the position of said functional element on said track remains substantially unaltered.

9. The mechanism according to claim 1, wherein the location of the connection of said control arm to said further structural element of the mechanism is variable, and wherein a variation thereof is associated with a simultaneous change in the position of said functional element on said track.

10. The mechanism according to claim 1, wherein a change in the connecting location brings about an altered change in a position of said functional element on said track during the pivoting of the backrest support.

11. The mechanism according to claim 1, wherein said further structural element of the mechanism is a part of a base support of the mechanism.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) Two exemplary embodiments of the invention are explained in more detail in the following text with reference to the drawings, in which:

(2) FIG. 1 shows a sectional illustration of a first mechanism with a soft setting of the pivoting resistance in a starting position,

(3) FIG. 2 shows a sectional illustration of the mechanism from FIG. 1 with a soft setting of the pivoting resistance in a pivoted position,

(4) FIG. 3 shows a sectional illustration of the mechanism from FIG. 1 with a hard setting of the pivoting resistance in a starting position,

(5) FIG. 4 shows a sectional illustration of the mechanism from FIG. 1 with a hard setting of the pivoting resistance in a pivoted position,

(6) FIG. 5 shows a perspective illustration of the mechanism from FIG. 1 with a hard setting of the pivoting resistance,

(7) FIG. 6 shows a sectional illustration of a second mechanism with a soft setting of the pivoting resistance in a starting position,

(8) FIG. 7 shows a sectional illustration of a second mechanism with a hard setting of the pivoting resistance in a starting position.

DESCRIPTION OF THE INVENTION

(9) All of the figures show the invention merely in a schematic manner and with its essential constituent parts. Identical reference signs in this case correspond to elements with an identical or comparable function.

(10) The figures show parts of a pivoting mechanism 1 for an office chair, wherein only the structural elements that are absolutely necessary for understanding the present invention are illustrated.

(11) The pivoting mechanism 1 comprises a base support 2 having a conical receptacle 3 for the upper end of a chair column, a seat support 4 and a backrest support 5. In this case, the side pieces of the backrest support 5, which is fork-shaped in plan view, are arranged on either side of the base support 2.

(12) The front end 6 of the base support 2 is connected to the front end 7 of the substantially horizontally arranged seat support 4 via a rotary/sliding joint 8 (not depicted in detail). The rear end 12 of the seat support 4 is furthermore connected pivotably to the backrest support 5, to be more precise to an upper side-piece part of the backrest support 5, at bearing points 13. Just as the seat support 4 can be provided with a seat, the backrest support 5 can also be provided with a backrest, wherein neither the type of seat nor the type of backrest is important for the invention. The backrest support 5 is furthermore articulated on the base support 2 with its front end 14, thereby forming the main pivot axis 9, extending transversely to the chair longitudinal direction 11, of the mechanism 1. The bearing points 13 are located behind the main pivot axis 9, as seen in the chair longitudinal direction 11.

(13) When a user leans against the backrest, the backrest support 5 can be transferred from its starting position, illustrated in FIGS. 1 and 3, into a pivoted position, as is illustrated for example in FIGS. 2 and 4. In order to set the restoring force of the backrest support 5, provision is made of a spring mechanism 15, the functioning of which is explained in detail in the following text.

(14) The spring mechanism 15 comprises a helical compression spring 16 arranged centrally in the mechanism 1. In the figures, this compression spring 16 is illustrated only in part for reasons of clarity. A guide device 17, in the form of a hollow cylinder having a guide rod 18 running through it, is inserted in a parallel manner in the compression spring 16, said guide rod 18, as anti-kink protection, preventing the compression spring 16 from bending during compression. The guide device 17 forms a spring seat 19 at the fixed end 21 of the compression spring 16. This spring seat 19 is mounted in an articulated manner at the front end 6 of the base support 2. The guide rod 18 is connected to a spring seat 20 at the movable end 23 of the compression spring 16. This spring seat 20 is connected to a variable-position functional element 22 in the form of a pin-shaped rolling and/or sliding body. The axis 24 of this rolling and/or sliding body 22 extends in this case parallel to the main pivot axis 9 of the mechanism 1. In the starting position of the backrest, the axis 24 of the functional element 22 is located in front of the main pivot axis 9 of the mechanism 1, as seen in the chair longitudinal direction 11. The functional element 22 has two needle bearings 27 for supporting the functional element 22 in a rotational manner on a supporting and/or guide track 25 which is formed by a concave bearing face of a pivot lever 28, said bearing face being open towards the front, as seen in the chair longitudinal direction 11. The pivot lever 28, acting as actuating element, is embodied as part of the backrest support 5 and is connected to the front end 14 of the backrest support 5 in a rotationally fixed manner beneath the main pivot axis 9 of the mechanism 1. The main pivot axis 9 of the mechanism 1 is at the same time the rotation axis of the pivot lever 28.

(15) A lower, fixed end 29 of a coupler 31 that serves as a control arm is pivotably connected to the functional element 22. A lug 32 provided at the end 29 of the coupler 31, said lug 32 surrounding the functional element 22, serves for this purpose.

(16) The exemplary embodiment illustrated in FIGS. 1 to 5 is described in more detail in the following text.

(17) Attached to the upper, movable end 33 of the coupler 31 is a cylindrical clamping pin 34, the longitudinal centre axis 35 of which extends parallel to the main pivot axis 9 of the mechanism 1. Here, too, a lug 36 provided at the end 33 of the coupler 31 serves to guide the clamping pin 34. The clamping pin 34 is supported in a correspondingly shaped receptacle 37 on the underside 38 of the base support 2, such that the coupler 31 is clamped between the functional element 22 and the base support 2.

(18) The receptacle 37 is part of a receiving plate 39 which, together with a Bowden cable 41 that serves as an adjusting element and is illustrated only in part in FIGS. 1 and 2, forms an adjustment device 42 for the coupler 31. For this purpose, the receiving plate 39 has a number of mutually adjoining receptacles 37, into which the free end 33 of the coupler 31 can be successively moved. The Bowden cable 41, which is embodied such that it can move the coupler 31 from one receptacle 37 to the next receptacle 37 and back again, is connected to the free end 33 of the coupler 31 and is supported at suitable points of the base support 2.

(19) The receptacles 37 are arranged on the receiving plate 39 such that the coupler 31 can be pivoted on a circular path about its articulation point 44 on the functional element 22, without the connection between the coupler 31 and the underside 38 of the base support 2 being lost. The articulation point 44, which is indicated in FIGS. 1 and 5, is determined by the connection of the lug 32 to the functional element 22. The compression spring 16 is perpendicular or substantially perpendicular to the supporting and/or guide track 25 in the non-pivoted state of the backrest. Therefore, when the clamping pin 34 is moved from one receptacle 37 to the next, essentially only the force which is necessary to overcome the separating strips that separate the individual hollow-like receptacles 37 from one another needs to be applied.

(20) When the backrest support 5 is pivoted downwards and to the rear in the pivoting direction 46, the pivot lever 28 connected to the backrest support 5 likewise pivots in the same manner, with the result that the functional element 22, held at a defined distance from the base support 2 by the coupler 13, is moved on the supporting and/or guide track 25. This results in a defined movement of the functional element 22 depending on the pivoting movement of the backrest support 5.

(21) In the example shown in FIGS. 1 and 2, the free end 33 of the coupler 31 is located in the rearmost receptacle 37, as seen in the chair longitudinal direction 11, of the receiving plate 39, with the result that the softest setting of the spring force setting is defined. In the starting position of the backrest, the longitudinal centre axis 35 of the clamping pin 34 is located behind the main pivot axis 9 of the mechanism 1, as seen in the chair longitudinal direction 11. When the backrest support 5 is pivoted, the functional element 22 moves upwards in the direction of the main pivot axis 9 and at the same time forwards in the direction of the front end 6 of the base support 2. As a result, the distance between the spring seats 19, 20 decreases, and the compression spring 16 is compressed.

(22) If the free end 33 of the coupler 31 is moved, with the aid of the Bowden cable 41, from the rearmost receptacle 37, as seen in the chair longitudinal direction 11, into the front receptacle 37, as shown in FIGS. 3 and 4, the hardest setting is carried out as a result. The supporting and/or guide track 25 remains unaltered in this case, and in particular the gradient of the track 25 does not change. In the starting position of the backrest, the longitudinal centre axis 35 of the clamping pin 34 is then located in front of the main pivot axis 9 of the mechanism 1, as seen in the chair longitudinal direction 11, and just behind the axis 24 of the functional element 22. As a result of the adjustment device 42 being actuated, the position of the coupler 31 changes relative to the position of the compression spring 16, to be more precise relative to the spring longitudinal direction 47, but not the length of the coupler 31. Therefore, when the backrest support 5 is pivoted, an altered ratio of the acting forces arises, this being expressed in an altered movement of the functional element 22.

(23) When the backrest support 5 is pivoted, the functional element 22 moves downwards away from the main pivot axis 9 and at the same time forwards in the direction of the front end 6 of the base support 2. As a result, the distance between the spring seats 19, 20 decreases much more greatly and the compression spring 16 is compressed more strongly than in the case of the above-described soft setting. At the same time, the active lever arm (not shown) which is essential for the pivoting movement of the backrest support 5 is enlarged, said lever arm being determined by the distance between the axis 24 of the functional element 22 and the main pivot axis 9 of the mechanism 1. At the same time, on account of the changed position of the compression spring 16, coupler 31 and pivot lever 28 with respect to one another, the sum of the forces effectively acting on the pivot lever 28 increases. Overall, this results in considerably increased pivoting resistance.

(24) Overall, in spite of the only small adjustment travel between the rearmost receptacle 37 and the front receptacle 37 of the adjustment device 42, a large adjustment range of the spring force adjustment arises. In other words, as a result of a comparatively small change in the position of the free end 33 of the coupler 31, a spring force adjustment from a very soft to a very hard setting and vice versa can take place.

(25) In the following text, the exemplary embodiment illustrated in FIGS. 6 and 7 is described in more detail. This exemplary embodiment differs from the above-described exemplary embodiment primarily by the manner in which the upper end 33 of the coupler 31 is connected to the base support 2. Instead of a self-locking configuration, locking that is establishable with the aid of an additional connecting element 48 is provided. This results, in addition to an altered adjustment device 42, in particular in an altered change in position of the functional element 22 on the supporting and/or guide track 25 during pivoting of the backrest support 5. All further essential features, in particular the resulting functional advantages of the mechanism 1, remain the same, however, or result in a corresponding manner.

(26) The additional connecting element 48 is articulated on the upper, movable end 33 of the coupler 31. The connecting element 48 comprises a pawl 49. The connecting element 48, which is pivotable about a locking pivot axis 50 extending parallel to the main pivot axis 9 of the mechanism 1, is supported on a planar supporting face 52 by way of its one side 51 facing the base support 2. This supporting face 52 is provided on the underside 38 of the base support 2, rigidly connected to the base support 2, and defines a rectilinear guide track for the upper end 33 of the coupler 31 when the pivoting resistance is adjusted.

(27) The position of the coupler 31 between the functional element 22 and base support 2 is maintained in that the pawl 49 provided on the opposite side 53 of the connecting element 48, that is to say the side facing away from the supporting face 52, engages in locking elements in the form of locking teeth 54 and thus locks the connecting element 48 and thus the coupler 31 on the base support 2, forming a ratchet. The locking teeth 54 are arranged in the form of a rectilinear tooth strip extending parallel to the supporting face 52 and, together with the supporting face 52 to which they are firmly connected, form the further structural element within the meaning of the invention. Every time the backrest support 5 is pivoted in the pivoting direction 46, the coupler 31 is urged in the direction of the supporting face 52. As a result, the coupler 31, to be more precise the top side 51 of the connecting element 48 of the coupler 31, is supported on the supporting face 52. Displacement of the connecting element 48 on the flat supporting face 52 in the direction of a softer setting, upwardly to the right in the figures, is prevented, however, in that the pawl 49 locks in the locking teeth 54.

(28) In the example shown in FIG. 6, the connecting element 48 is supported on the rearmost abutment point, as seen in the chair longitudinal direction 11, of the supporting face 52, and the pawl 49 is located next to the rearmost locking tooth 54, as seen in the chair longitudinal direction 11, in the tooth strip, with the result that the softest setting of the spring force setting is defined. In the starting position of the backrest, the locking pivot axis 50 of the connecting element 48 is located behind the main pivot axis 9 of the mechanism 1, as seen in the chair longitudinal direction 11.

(29) In order to alter the pivoting resistance from soft to hard, provision is made of a first Bowden cable 56 (indicated merely symbolically and away from its actual position in the figures for the sake of clarity) as adjusting element, said first Bowden cable 56 acting on a first engagement point 57 of the connecting element 48 and being supported at suitable points on the base support 2. This first engagement point 57 is provided on the connecting element 48 such that the connecting line between the first engagement point 57 and the locking pivot axis 50 of the connecting element 48 extends parallel to the supporting face 52. In the event of a pull in the first pulling direction 58 defined thereby, the pawl 49 is unlocked and the locking brought about by the pawl 49 is overcome. The ratchet formed by the pawl 49 and locking teeth 54 acts in this case as a type of limit-force ratchet, in which the locking forces can be overcome by a pull in the first pulling direction 58. An increase in the pivoting resistance, i.e. an alteration in the position of the coupler 31 into a respectively harder position, is possible in each case by renewed actuation of the first Bowden cable 56.

(30) On the other hand, if the pivoting resistance is intended to be reduced, that is to say the coupler 31 moved into a softer position, this is not possible with the aid of the first Bowden cable 56. This is because, on account of the connecting element 49 being supported on the supporting face 52 with simultaneous engagement of the pawl 49 in the locking teeth 54, the ratchet formed by the pawl 49 and locking teeth 54 acts as a kind of directional ratchet, which does not allow a movement of the connecting element 48 counter to the first pulling direction 58. Therefore, in order to alter the pivoting resistance from hard to soft, provision is made of a second Bowden cable 59 (indicated merely symbolically and away from its actual position in the figures for the sake of clarity) as adjusting element, said second Bowden cable 59 acting at a second engagement point 60, different from the first engagement point 57, of the connecting element 48 and being supported at suitable points on the base support 2. This second engagement point 60 is provided on the connecting element 48 such that it is not located on the connecting line between the first engagement point 57 and the locking pivot axis 50 of the connecting element 48. Instead, the second engagement point 60 is arranged on a lever arm 61, acting on the pawl 49, of the connecting element 48 such that in the event of a pull in the second pulling direction 62, which is different from the first pulling direction 58, a torque acts on the pawl 49 such that the latter is unlocked. In other words, the pawl 49, which is embodied as part of the connecting element 48, is raised and pivoted out of the locking teeth 54 in that the entire connecting element 48 is pivoted about its locking pivot axis 50 on the coupler 31. A reduction in the pivoting resistance, i.e. an alteration in the position of the coupler 31 into an in each case softer position, is then possible in each case by renewed actuation of the second Bowden cable 59.

(31) If the upper end 33 of the coupler 31 was moved, with the aid of the first Bowden cable 56, from the rearmost engagement point, as seen in the chair longitudinal direction 11, of the supporting face 52 to the front engagement point, as shown in FIG. 7, the hardest setting is carried out as a result. In the starting position of the backrest, the locking pivot axis 50 of the connecting element 48 is then located again in front of the main pivot axis 9, as seen in the chair longitudinal direction 11, of the mechanism 1 and just behind the axis 24 of the functional element 22.

(32) During the setting of the pivoting resistance, an alteration in the position of the coupler 31 always takes place such that the upper end 33 of the coupler 31 is moved in a linear manner corresponding to the guide track defined by the supporting face 52. The position of the functional element 22, connected to the fixed end 29 of the coupler 31, on the supporting and/or guide track 25 is likewise altered in the process. In other words, not only does the upper end 33 move on the supporting face 52 but the fixed end 29 of the coupler 31 also moves on the supporting and/or guide track 25 when the pivoting resistance is increased towards the front in the chair longitudinal direction 11 and when the pivoting resistance is reduced towards the rear in the chair longitudinal direction 11. Thus, the coupler 31 is always moved as a whole when the pivoting resistance is changed.

(33) During the setting of the pivoting resistance, the functional element 22 moves in a defined, constant relationship with respect to the movement of the upper end 33 of the coupler 31. While the upper end 33 of the coupler 31 moves in each case in the first pulling direction 58 or counter to the first pulling direction 58, the fixed end 29 of the coupler 31 moves with the functional element 22 on a circular path around the fixed point 21 of the helical compression spring 16. On account of this movement path, when the pivoting resistance is set, the helical compression spring 16 is not compressed or is only compressed to an insignificant extent. The pivoting resistance is therefore particularly easy to set.

(34) All of the features represented in the description, the following claims and the drawings can be essential to the invention both individually and in any desired combination with one another.

LIST OF REFERENCE SIGNS

(35) 1 Pivoting mechanism 2 Base support 3 Conical receptacle 4 Seat support 5 Backrest support 6 Front end of the base support 7 Front end of the seat support 8 Rotary/sliding joint 9 Main pivot axis 10 (not used) 11 Chair longitudinal direction 12 Rear end of the seat support 13 Bearing point 14 Front end of the backrest support 15 Spring mechanism 16 Helical compression spring 17 Guide device 18 Guide rod 19 Spring seat 20 Spring seat 21 Fixed end of the spring 22 Functional element, rolling and/or sliding body 23 Movable end of the spring 24 Axis of the functional element 25 Supporting and/or guide track 26 (not used) 27 Needle bearing 28 Pivot lever 29 Fixed end of the coupler 30 (not used) 31 Coupler 32 Lug 33 Movable end/free end of the coupler 34 Clamping pin 35 Longitudinal centre axis 36 Lug 37 Receptacle 38 Underside of the base support 39 Receiving plate 40 (not used) 41 Bowden cable 42 Adjustment device 43 (not used) 44 Articulation point 45 (not used) 46 Pivoting direction 47 Spring longitudinal direction 48 Connecting element 49 Pawl 50 Locking pivot axis 51 Top side of the connecting element 52 Supporting face 53 Underside of the connecting element 54 Locking tooth 55 (not used) 56 First Bowden cable 57 First engagement point 58 First pulling direction 59 Second Bowden cable 60 Second engagement point 61 Lever arm 62 Second pulling direction