Adjusting mechanism for adjusting a restoring force acting on the backrest of a chair, and office chair provided with such an adjusting mechanism

Abstract

The adjusting mechanism serves for the setting of a restoring force acting on the backrest of a chair. A back support and a seat support are fastened on a support. A setting mechanism configured in the manner of scissors is provided for the weight setting. Said setting mechanism has two scissor arms which are connected to one another via a scissor pin. One of said scissor arms is formed by a spring element and is fastened with its front-side spring end on said support. The back spring end is fastened on said scissor pin. Said first scissor arm is connected to said back support in the manner of a connecting rod. An active lever length is defined between said scissor pin and a support pin about which said back support is mounted pivotably. A compact construction mode is achieved by the configuration of said scissor arm as a spring element.

Claims

1. An adjusting mechanism for setting a restoring force acting on a backrest of a chair, the adjusting mechanism comprising: a spring element for generating the restoring force; a support and a back support mounted on said support such that said back support is configured to pivot about a support pin; wherein said mechanism comprises: a setting mechanism borne with a setting pin, said setting mechanism being configured in the manner of scissors for a weight-dependent setting of the restoring force, said setting mechanism comprising a scissor pin and further comprising a first scissor arm and a second scissor arm and wherein the first and second scissor arms being connected to one another and configured to rotate about the scissor pin, said first scissor arm being mounted on said backrest support by the setting pin such that said first scissor arm is configured to pivot about the setting pin; and a lever length being defined between said support pin and said scissor pin, said lever length being changeable with the aid of an adjusting device for setting the restoring force by pivoting said setting mechanism, wherein said second scissor arm is formed by said spring element, and said spring element is mounted on said support at a first end by said scissor pin and thereby connected to the first scissor arm, and the spring element is mounted on an articulation pin at a second end.

2. The adjusting mechanism according to claim 1, wherein said spring element is able to be pivoted about said articulation pin for setting said lever length.

3. The adjusting mechanism according to claim 1, wherein said scissor pin engages a first oblong hole inside said back support.

4. The adjusting mechanism according to claim 1, wherein said adjusting device is able to be operated manually, and acts via a setting arm on said scissor pin for the setting of said scissor pin.

5. The adjusting mechanism according to claim 4, wherein said setting arm is mounted such that it is able to be rotated about the articulation pin, and is connected furthermore mechanically to said scissor pin via a second oblong hole in which said scissor pin is positioned.

6. The adjusting mechanism according to claim 1, wherein said adjusting device has a setting wheel which is rotatable about an adjusting pin inside said support, via which said scissor pin is adjusted upon a rotation of said setting wheel.

7. The adjusting mechanism according to claim 6, wherein said setting wheel is configured eccentrically and said setting wheel rolls on said setting arm.

8. The adjusting mechanism according to claim 7, wherein said setting wheel has several indentations in the peripheral direction which in each position define a setting position, a fixation bolt being positioned, in a respective setting position, in a respective indentation.

9. The adjusting mechanism according to claim 8, wherein said fixation bolt is fastened on said setting arm.

10. The adjusting mechanism according to claim 8, wherein said fixation bolt is arranged with respect to said indentations such that a self-locking fixation is achieved in the chosen setting position.

11. The adjusting mechanism according to claim 8, wherein said fixation bolt is positioned substantially on a vertical line which intersects said adjusting pin.

12. The adjusting mechanism according to claim 1, wherein a rotation of setting wheel is converted into a linear movement of an oblique slide way, and said slide way is connected mechanically to said scissor pin for the adjustment of said scissor pin.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment of the invention is explained more in detail in the drawings. These are partly diagrammatic representations.

(2) FIG. 1A is a side view of an office chair with a synchronizing mechanism with upright backrest,

(3) FIG. 1B is the office chair according to FIG. 1A in a loaded state with an inclined backrest,

(4) FIG. 2A is a perspective view of an adjusting mechanism with a back support and a seat support in a basic position (upright backrest),

(5) FIG. 2B is an enlarged detail of the view according to FIG. 2A,

(6) FIG. 2C is, similar to FIG. 2B, an enlarged detail of the view of an adjusting mechanism with a back support and a seat support in an inclined position (inclined backrest),

(7) FIG. 3A is a sectional side view of the adjusting mechanism according to cutting line A-A in FIG. 2A without support sides in the heavy weight setting, in the basic position,

(8) FIG. 3B is a side view similar to FIG. 3A in the heavy weight setting, in the inclined position,

(9) FIG. 3C is a sectional side view of the adjusting mechanism according to cutting line A-A in FIG. 2A, the adjusting mechanism being in the heavy weight setting, in the basic position,

(10) FIG. 3D is, similar to FIG. 3C, a sectional side view of the adjusting mechanism according to cutting line A-A in FIG. 2A, the adjusting mechanism being in the heavy weight setting, in the inclined position,

(11) FIGS. 4A to 4D are the representations corresponding to the FIGS. 3A to 3D in the light weight setting,

DETAILED DESCRIPTION

(12) An office swivel chair with a synchronizing mechanism shown on FIGS. 1A and 1B comprises a back 2, a seat 4, a seat or adjusting mechanism 6 which is arranged below the seat 4 and in which the individual components for setting a restoring force which acts on the back 2 are integrated. Furthermore, a standing tube 8 can be seen which is connected to a non-illustrated foot part. The standing tube is usually configured as a telescopic tube, via which a height setting can be performed. A movement of the seat 4 and that of the back 2 are coupled to one another by way of the synchronizing mechanism. To be precise, in the case of an adjustment of the back 2 from the position shown in FIG. 1A into the position shown in FIG. 1B, the seat is transferred from a substantially horizontal orientation according to FIG. 1A into an obliquely rearwardly inclined position.

(13) The synchronizing mechanism contains a back support 12, via which the back 2 is fastened. Furthermore, the synchronizing mechanism contains a seat support 14 which carries the seat 4.

(14) As can be gathered from FIGS. 2 to 4, the adjusting mechanism 6 contains a housing which is of a shell-like configuration in the exemplary embodiment and is called a support 16 in the following text. The seat support 14 and the back support 12 are fastened to the support 16. Here, the back support 12 is articulated such that it can be pivoted about a support pin A1 which is defined by a support shaft. Preferably, the back support is exclusively mounted on the support 16 the via the support pin. The support 16 has two side cheeks 18 which enclose a central space between them.

(15) The adjusting mechanism 6 contains a setting mechanism 20 which is configured in the manner of scissors with a first scissor arm 20A and a second scissor arm 20B which is formed by a spring element 24. The first scissor arm 20A is mounted on the back support 12 such that the first scissor arm 20A can be pivoted via a setting shaft which defines a setting pin A2. Both scissor arms 20A, 20B are connected to each other via a scissor bolt which defines a scissor pin A3. The spring element 24 is mounted with its front-side end directly on support 16 via an articulation bolt which defines an articulation pin A4.

(16) An active lever length W1 is defined between the support pin A1 and the scissor pin A3. (see FIGS. 3A and 4A).

(17) In the exemplary embodiment, the seat support 14 and the back support 12 are pivotably connected to each other on an action pin A6. Here, the action pin A6 is arranged in a rear region of the adjusting mechanism 6, particularly behind the setting pin A2. Furthermore, the seat support 14 is fastened pivotably movably to the support 16 via a supporting pin A7 in a front-side region.

(18) The support 16 isas it can be seen particularly from FIG. 2Aof a shell-like configuration and accommodates the individual components of the adjusting mechanism 6 in its free internal space. Here, the seat support 14 is configured like a frame part which has a L-shape cross-section, the one horizontal L-arm having fastening holes in order to fasten the seat 4.

(19) The respective vertical L-arm which is directed downwards serves on the other hand for fastening the seat support 14 on the support 16 (preferably exclusively via supporting pin A7) and for fastening on the back support 12 (preferably exclusively via action pin A6).

(20) The seat support 14 surrounds the support 16 with its vertical L-shaped legs in the way of a frame.

(21) The back support 12 has two opposite flat side components or side cheeks which are connected to each other in particular via a median and a rear transverse web.

(22) Furthermore, it can be seen particularly from FIG. 2A that the action pin A6 connects both side cheeks of the back support 12.

(23) The shaft which forms the scissor pin A3, at least the shaft ends, extends in each possible position in a respective first oblong hole 22 inside a respective side cheek of the back support 12. In particular, the respective shaft ends are accommodated in the first oblong hole 22, which ends are secured for slipping in the direction of the shaft by means of a securing element which in particular engages the first oblong hole 22 here.

(24) As can be gathered furthermore from FIGS. 2A to 2C, altogether two spring elements 24 are arranged in the exemplary embodiment which are arranged in parallel next to each other and are configured in particular as compression springs. The spring elements 24 are connected to each other at their front-side end via the articulation pin A4, and at their rear spring end via the articulation pin A3.

(25) The first scissor arm 20A is configured in particular as a flat mechanically rigid component, in particular as a sheet metal component of the kind of a tension or compression connecting rod. The tension connecting rod is configured here in particular as being cranked, i.e. it has two partial regions which are in an (obtuse-) angle arrangement to one another. This is particularly advantageous for a place-saving construction mode.

(26) In the exemplary embodiment, a tension connecting rod is arranged each time at both sides of the spring elements 24. Each of the tension connecting rods is connected here to a respective side cheek of the back support 12 via a respective bolt which defines the setting pin A2.

(27) An adjusting device 26 is arranged to adjust the active lever length W. This device is preferably arranged in the exemplary embodiment between both spring elements 24.

(28) The adjusting device 26 has in the exemplary embodiment several toothed wheels 28 to configure a transmission. Two toothed wheels 28 are provided in the exemplary embodiment. The desired weight setting can be performed by rotating a handwheel 30 which is arranged outside the support 16 and which is connected via a shaft 32 to one of the toothed wheels 28.

(29) The exerted rotation is transmitted via the toothed wheels 28 to an eccentric setting wheel 34. This latter is rotatable about a adjusting pin A8. The adjusting pin A8 is formed again by a bolt or a shaft and is arranged coaxially with respect to the rotation axis of the second toothed wheel 28. The second toothed wheel 28 and the setting wheel 34 are therefore arranged on a common shaft.

(30) By an eccentric design of the setting wheel 34, it is understood that a peripheral line is not arranged concentrically with the adjusting pin A8. The radial distance of the peripheral line of the setting wheel 34 varies rather. On this peripheral line of the setting wheel 34, several successive indentations 36 are configured which have for example in each possible position an angular distance of a few degrees with respect to one another. In the exemplary embodiment, the setting wheel 34 is configured as a worm wheel.

(31) Furthermore, the adjusting device 26 contains a setting arm 38 (FIGS. 3C, 3D and FIGS. 4C, 4D), which is also mounted pivotably movably on the support 16. Particularly, the setting arm 38 is mounted here on the shaft which forms the articulation pin A4, together with the spring elements 24.

(32) At its back end, the setting arm 38 has a second oblong hole 40, through which the shaft of the scissor pin A3 is guided. The setting wheel 34 is connected mechanically in a median region of the setting arm 38 to the latter. To this end, the setting arm 38 has a fixation bolt 42 which protrudes from the setting arm 38 in the traverse direction. The setting wheel 34 rolls with the indentations 36 on this fixation bolt 42. Preferably, the setting arm is configured again as a mechanically rigid component which has the shape of a plate or a strip, in particular as a sheet metal component.

(33) As can be gathered for example from FIGS. 3C,3D, the fixation bolt 42 and the adjusting pin A8 are on a common vertical line 44.

(34) The fixation bolt 42 is forced elastically towards the setting wheel 34 into a respective indentation 36. This pressure exerted by an elastic force is achieved automatically in the exemplary embodiment by the special orientation and mounting position of the respective spring element 24, which results in a resulting force component in the vertical direction. As an alternative or complement, a separate spring element is arranged which forces the fixation bolt 42 into the indentations 36.

(35) The method of operation of the adjusting mechanism 6 for the weight setting is as follows:

(36) In the basic position (FIGS. 3A, 4A), the active lever length W1 is changed to a great extent force-free with the help of the adjusting device 26, for example from the weight setting heavy, which is shown on FIG. 3A, into the weight setting light, which is shown on FIG. 4A. The weight setting takes place by a rotation on the handweel 30 which is transmitted such that the setting wheel 34 rotates. In this way, the setting wheel 34 rolls on the fixation bolt 42 such that the radial distance between the setting arm 38 and the adjusting pin A8 varies. This leads to a pivoting of the setting arm 38 about the articulation pin A8. Simultaneously, a restricted guidance of the scissor pin A3 takes place via the second oblong hole 40 in the direction of the double arrow D1, which is drawn on FIG. 3A.

(37) As the articulation pin A4 and the setting pin A4 are aligned with one another or coincide in the basic position, no length change of the spring element 24 is involved by this adjusting motion and thus by the rotation of the spring element 24 about the articulation pin A4. The adjustment is therefore force-freeexcept possible friction forcesand can thus be carried out very easily.

(38) The active lever length W1, which has been set once, remains constant even in the case of an inclination of the back support 12. In the case of such an inclination, the back support 12 rotates about the support pin A1 such that its front-side end and herewith the setting pin A2 is pulled upwards (in this regard, see the FIGS. 3B, 4B). This is why the setting pin A2 pivots in the direction of the double arrow D2, which is represented in FIG. 3. The active lever length W1 is thus generally changed via the adjusting device 26 by the fact that the scissor pin A3 is pivoted about the articulation pin A4.

(39) The particular advantage in the case of this embodiment can be seen in the fact that the adjustment takes place nearly weightless, since no elastic forces are exerted in the basic position. The position of the scissor pin A3 is fixed in the desired position because of a self-locking of the adjusting device 26, and is maintained even in the case of an inclination adjustment.

(40) The special embodiment of the adjusting device 26, which is described herein, is fundamentally also transformable irrespective of the special combination of features recited in the claims. In particular, an adjusting device 26 of this kind having particularly the eccentrically mounted setting wheel 24 can be used in the case of other adjusting mechanisms, in particular in the case of the adjusting mechanism described in the international WO 2011/141107 A1. In this respect, the embodiment of this adjusting device 26 is considered to be an independent inventive aspect, and the filing of a divisional application remains reserved.

(41) Overall, the described embodiment achieves a compact mechanism for weight setting which is distinguished, in particular, by a virtually force-free weight setting in the basic position. Furthermore, a comparable profile of the restoring force is achieved over the adjusting travel in the case of an adjustment of the inclination, independently of the performed weight setting. In particular, the ratios of the restoring forces in the upright and the inclined end positions are at least similar to one another in a light weight setting and in a heavy weight setting, and the profile of the restoring force over the inclination travel is also at least largely independent of the performed weight setting.

(42) TABLE-US-00001 List of designations 2 Back 4 Seat 6 Adjusting mechanism 8 Standing tube 12 Back support 14 Seat support 16 Support 18 Side cheek 20 Setting mechanism 20A First scissor arm 20B Second scissor arm 22 First oblong hole 24 Spring element 26 Adjusting device 28 Toothed wheel 30 Handwheel 32 Shaft 34 Setting wheel 36 Indentation 38 Setting arm 40 Second oblong hole 42 Fixation bolt 44 Vertical line A1 Support pin A2 Setting pin A3 Scissor pin A4 Articulation pin A5 Pivot pin A6 Action pin A7 Supporting pin A8 Adjusting pin D1 First double arrow D2 Second double arrow W Active lever length