WO2011096880A1

WO2011096880A1 - Adjustment device for a chair

Info

Publication number: WO2011096880A1
Application number: PCT/SE2011/050117
Authority: WO
Inventors: Johan Alriksson; Petter Åstradsson
Original assignee: Support Design Ab
Priority date: 2010-02-08
Filing date: 2011-02-03
Publication date: 2011-08-11

Abstract

An adjustment device (2) for a chair (1 ) with a seat (3) and a back rest (4) comprising a frame (6) and a back cushion (5). The adjustment device (2) is attached to the back cushion (5) and is adapted to slide in relation to the frame (ό) to adjust the height of the back cushion in relation to the seat (3). The frame (6) or a support plate (10) attached to the frame (ό) comprises a first and a second slot ( 12, 13) in which the adjustment device (2) is adapted to slide. It is characterised in that the adjustment device (2) comprises a locking plate (8) and a tensioning device (7). The locking plate (8) has at least two locking arms (8a, 8b) protruding in opposite directions from first sides of the plate (8) transverse to the extension direction of the first and second slot ( 12, 13) and the tensioning device (7) is adapted to create a force (F) on a surface (8') of the locking plate (8) acting in a direction essentially transverse to the surface (8'). The locking arms (8a, 8b) are adapted to slide in the first and second slots ( 12, 13) when no force (F) is applied and to lock the locking arms (8a, 8b) in the slots ( 12, 13) when the force (F) is applied.

Description

ADJUSTMENT DEVICE FOR A CHAIR

Technical field

[0001 ] The present invention relates generally to adjustment device for a chair according to the preamble of patent claim 1 .

Background art

[0002] In prior art chairs it is known to arrange the back cushion of the back support height adjustable in relation to the seat of the chair. The seat and the back cushion are often arranged on a frame, wherein the frame can comprise two parts pivotably attached to each other. The seat part is arranged on one frame part and the back cushion is arranged on the other frame part. It is also known to arrange the back cushion slideably attached to the frame and to lock the back cushion and the frame relative each other. The previously known locking device can for example be a screw which during tightening increases the friction between the back cushion and the frame.

[0003] Another locking device is described in Japanese patent application

JP1 0033303. Here the frame of the back rest comprises a first and a second slot in which a locking device attached to the back cushion is adapted to slide to adjust the height of the back cushion in relation to the seat. A problem with this type of locking device is that the back cushion can rotate in relation to the frame. It can also be difficult to adjust due to the need of a pressing force created by the fingers of the user.

Summary of invention

[0004] An object of the present invention is to provide an adjustment device for a chair which is easy to maneuver for the user and which firmly locks the back cushion in the desired position. [0005] The above mentioned object is according to the invention provided by an adjustment device for a chair according to the characterizing part of patent claim 1 .

[0006] The invention relates to an adjustment device for a chair with a seat and a back rest, wherein the back rest comprises a frame and a back cushion. The adjustment device is attached to the back cushion and is adapted to slide in relation to the frame to adjust the height of the back cushion in relation to the seat. The frame, or a support plate attached to the frame, comprises a first and a second slot in which the adjustment device is adapted to slide. The invention is characterized in that the adjustment device comprises a locking plate and a tensioning device. The locking plate has at least two locking arms protruding in opposite directions from first sides of the plate, transverse to the extension direction of the first and second slot. The tensioning device is adapted to create a force on a surface of the locking plate, acting in a direction essentially transverse to the surface. The locking arms are adapted to slide in the first and second slots when no force is applied and to lock the locking arms in the slots when the force is applied.

[0007] A construction according to the above is easy to maneuver for the user by adjusting and moving the tensioning device in the slots. Further, when the adjustment device is sliding in two parallel slots the back cushion is firmly locked in the desired position when the locking arms are pressed against the outer

horizontally arranged elongated edges of the slots.

[0008] !n an embodiment, the tensioning device is adapted to adjust a distance between the frame and/or the support plate and the locking plate.

[0009] When the tensioning device is used to adjust the distance between the frame and/or the support plate and the locking plate, the force on the locking plate can be adjusted. [001 0] !n another embodiment, the tensioning device is attached to the locking plate by means of a pin.

[001 1 ] Connecting the locking plate and the tensioning device with a pin or any other pin like object creates a simple yet effective and adjustable attachment arrangement. The pin can be connected to the locking plate directly or indirectly by attaching the pin directly in the locking plate or in an anvil resting against the surface the locking plate facing the back cushion.

[001 2] in another embodiment, the pin is adapted to slide in an intermediate guidance slot in the frame and/or in the support plate, arranged between the first and the second slot.

[001 3] By letting the pin connecting the tensioning device and the locking plate slide in a guidance slot between the first and the second slot it is possible to arrange the tensioning device to act centrally on the locking plate without interfering with the adjustability of the back support.

[0014] in another embodiment, the tensioning device is a lever attached to and adapted to pivot around an eccentric support part which is arranged to, directly or indirectly, be in contact with the frame and/or the support plate.

[0015] Using a tensioning device according to this embodiment simplifies the adjustability of the chair. The eccentric support part is so designed that when pivoting the lever from a first unlocked to a second locked position, the distance between the frame/support plate and the locking plate is decreased. This creates the force acting on the locking plate locking the locking arms in the first and second slot. However, it is also possible to use a tensioning device having the shape of a nut rotating around the extension axis of the pin or any other similar devices. [001 6] !n another embodiment, the eccentric support part is arranged to pivot around an end of the pin connecting the tensioning device and the locking plate. Further, the pin end can have a spherical or semi-spherical shape adapted to easily slide in a corresponding spherical or semi-spherical cavity in the support part.

[001 7] Using the pin end as a pivot point creates a rigid connection arrangement. Further, when the pin end acts in a correspondingly shaped cavity in the support part the friction forces between the support part and the pin end can be minimized. However, to further control the pivoting movement it is also possible to use other shapes than spherical or semi-spherical of the pin end and cavity. It is also conceivable that the wearing surfaces are covered by a friction decreasing layer, such as Teflon, oil or similar.

[001 8] in another embodiment, the eccentric support part is arranged to act against a casing attached to the frame and/or the support plate, wherein the casing comprises a surface with at least two recesses arranged separated from each other in a direction parallel to the extension direction of the slots.

[001 9] The recesses are preferably shaped after the support part of the lever, so that vertical movements of the locking plate, thus also the connected back support, is even further prevented when the tensioning device is in its locked position. The casing can also be used to cover and protect the moving parts.

[0020] in another embodiment, the locking arms are protruding from the locking plate at an angle in relation to the surface of the locking plate.

[0021 ] Having a pre-bent locking plate where the arms protrudes at an angle from the locking plate creates a distance between the surface of locking plate arranged parallel to the frame/support plate and the frame/support plate itself. Thus, the locking plate can slide in the slots without excessive friction between the parts. [0022] !n another embodiment, four locking arms are protruding from the locking plate and are arranged at each corner of the locking plate.

[0023] If the opposite outer corners of the locking arms are placed at a certain distance from each other, a rotational movement of the locking plate in relation to the support plate is prevented. Thus, each outer most corner of each locking arm is acting as a rotation stop when in contact with the edges of the slots. I.e. the back cushion is prevented from rotation in relation to the frame. This is for example possible by using four arms arranged at each corner of the locking plate or by using locking arms with a certain extension directed parallel to the first and second slots.

[0024] !n other embodiments, the locking arms are elastically connected to the plate and/or the locking plate is made of a flexible material.

[0025] if the entire locking plate is made of a flexible material, the locking plate flex when subjected to a force. A force acting essentially centrally on the locking plate will then automatically press the locking arms in a direction towards the outer edges of the slots, thus locking the locking plate in relation to the frame/support plate. This effect can be further increased by using locking arms which are elastically connected to the plate, thus they can pivot around their point of attachment in the plate. Of course, it is also possible to use a rigid locking plate with elastically connected locking arms.

[0026] Please note that any embodiment or part of embodiment could be combined in any way.

Brief description of drawings

[0027] The invention is now described, by way of example, with reference to the accompanying drawings, in which: Fig. l a discloses a chair with a back cushion in a first high position and an adjustment device in a locked state,

Fig. 1 b discloses the chair with a back cushion in a second low position and an adjustment device in an unlocked state,

Fig. 2a discloses a detail view of a first embodiment of the adjustment device viewed from a first direction from the rear of the chair,

Fig. 2b discloses a vertical cut view through the center of the adjustment device in fig. 2a,

Fig. 3a discloses a first view of a detail of the adjustment device in a first locked state,

Fig. 3b discloses a second A-A cut view of fig. 3a,

Fig. 3c discloses a third enlarged view of the adjustment device in a first locked state,

Fig. 4a discloses a first view of the adjustment device in a second unlocked state, Fig. 4b discloses a second A-A cut view of fig. 4a,

Fig. 4c discloses a third enlarged view of the adjustment device in a second unlocked state,

Fig. 5a discloses a second embodiment of an adjustment device in a first open position, and

Fig. 5b discloses a second embodiment of a tensioning device in a second locked position. Description of embodiments

[0028] In the following a detailed description of embodiments will be given. It will be appreciated that the figures are for illustration only and are not in any way restricting the scope. Thus, any references to direction, such as "horizontal" or "vertical", are only referring to the directions shown in the figures.

[0029] The expressions "seat" and "back cushion" comprises devices consisting one or several parts which are either hard of soft.

[0030] Figure 1 a and 1 b discloses a chair 1 , preferably a so called office chair, with the inventive adjustment device. The chair comprises a seat 3 and a back support 4. The back support 4 comprises a back cushion 5 adjustably attached to a frame 6. By adjusting the height of the back cushion 5 in relation to the seat 3, the chair 1 can be adapted to fit a large number of people. Preferably, the height of the back support of the chair is adjusted in an essentially vertical direction.

[0031 ] Figure l a discloses the chair 1 with the back cushion 5 in a first position and an adjustment device 2 in an unlocked state and figure 1 b discloses the chair 1 with the back cushion 5 in a second position and the adjustment device 2 in a locked state. In the unlocked state an embodiment of a tensioning device 7 located in a casing 14 attached to the frame 6, is rotated into a position essentially transverse the frame ό and in the locked state the tensioning device 7 is rotated into a position essentially parallel the frame 6. The tensioning device 7 according to this embodiment is more thoroughly described in figures 5a and 5b.

[0032] Figures 2a-b discloses detail views of an embodiment of the adjustment device 2, wherein fig. 2a is a view from the rear of the chair and fig. 2b is a vertical cut view through the center of the adjustment device.

[0033] The adjustment device 2 comprises a locking plate 8 attached to the back cushion 5 and a tensioning device 7. The tensioning device 7 is a force creating device mounted on a pin 9 connected to the locking plate 8 and adapted to act against a support plate 10 attached to the frame 6. in an alternative embodiment the frame ό itself can have the shape of an elongated support plate. The pin 9 can be connected to the locking plate 8 directly or indirectly by attaching the pin 9 directly in the locking plate 8 or in an anvil 15 resting against the surface of the locking plate 8 facing the back cushion 5.

[0034] The tensioning device 7 is creating a force F between the support plate 10 and the locking plate 8, acting in a direction essentially transverse to the plates 8, 10. This force F is created by adjusting the distance x between the support plate 10 and the locking plate 8 and it is bending the entire locking plate 8 or is pivoting at least two locking arms 8a, 8b protruding in opposite directions from the vertically arranged sides of the locking plate 8.

[0035] The locking arms 8a, 8b (see also figure 3a-c and fig 4a-c) arranged on the locking plate 8 are adapted to slide and to lock in a first and a second slot 1 2, 1 3 arranged essentially vertically in the support plate 1 0, in the surface facing the locking plate 8. Since the locking plate 8 is attached to the back cushion 5 and the support plate 10 is attached to the frame 6, when the locking plate 8 is sliding in the first and second slots 1 2, 1 3, the height of the back cushion 5 is adjusted in relation to the seat 3.

[0036] The pin 9 is adapted to slide in a through-going essentially vertical intermediate guidance slot 1 1 in the support plate 10. The guidance slot 1 1 is arranged in-between and parallel to the first and second slot 1 2, 1 3.

[0037] In the embodiment according to figures 2a-b the tensioning device is a force creating device having the form of a nut 7' rotating around the extension axis of the pin 9. Preferably, the nut 7' is engaging a thread arranged on the pin 9. [0038] The locking plate 8, which can be seen in more detail in figure 3a-c and 4a-c, is preferably made of a flexible material such as spring steel, other metal, composite or similar. When subjected to the force F from the tensioning device 7, either the entire plate 8 flex or either each locking arm 8a, 8b pivots around its attachment points in the locking plate 8.

[0039] The number of locking arms 8a, 8b is at least two but it is also

conceivable that four or more locking arms 8a, 8a^', 8b, 8b' are protruding from the locking plate 8. If four arms are used, the locking arms 8a, 8a^', 8b, 8b' is preferably arranged at each corner of the locking plate 8. Placing the locking arms 8a, 8a^', 8b, 8b' at a certain distance from each other prevents a rotational movement of the locking plate 8 in relation to the support plate 1 0. I.e. the back cushion 5 is prevented from rotation in relation to the frame 6. It is also possible to prevent this rotation by using locking arms 8a, 8b with a certain extension directed parallel to the first and second slots 2, 1 3. In this embodiment (which is not disclosed), each outer most corner of each locking arm is acting as a rotation stop when in contact with the edges of the slots 1 2, 1 3.

[0040] Figures 3a and 4a discloses a first view of the support plate 10 and the locking plate 8, with and without a tensioning force F acting on the locking plate 8. Figures 3b and 4b disclose a second A-A cut view of figures 3a and 4a. Figures 3c and 4c disclose a third enlarged view of the locking arms 8a arranged in the slot 1 3.

[0041 ] In figures 3a-c, when no force is acting on the locking plate 8, the locking arms 8a, 8b can slide freely in the first and second slot 1 2, 1 3. I.e. there is a distance between both the locking plate 8 and the support plate 1 0 and the locking arms 8a, 8a', 8b, 8b' and the elongated outer edges 1 2a, 1 3a of the slots 1 2, 1 3. The locking arms 8a, 8b are preferably protruding from the locking plate 8 at an angle a in relation to a surface 8' of the plate 8 so that the locking plate 8 can slide freely parallel to the support plate 1 0 when no force F is acting between the locking plate 8 and the support plate 1 0.

[0042] When a force F is acting on the locking plate 8, as in figure 4a-4c, the locking plate 8 is pressed towards the support plate 10 and the outer edges of the locking arms 8a, 8b are pressed against the elongated outer edges 1 2a, 1 3a of the slots 1 2, 1 3. Thus, the locking plate 8 is locked both in a vertical and rotational direction in relation to the support plate 1 0.

[0043] In the embodiment according to figures 3a-c and 4a-c, the surface 8' is essentially flat and the locking arms 8a, 8b are arranged at an angle a of between 5 and 85 degrees from the surface plane. Preferably, the arms 8a, 8b are arranged at an angle a between 30 and 60 degrees from the surface plane. When a force is acting on the locking plate 8, the outer edges of the arms 8a, 8b are pressed away from each other, i.e. the angle a decrease, preferably to an end angle of between 5 and 30 degrees from the surface plane, but of course are other end angles also possible. To be able to flex, either the locking arms are elastically connected to the plate 8 or the locking plate 8 itself is made of a flexible material, !t is also conceivable that the locking plate has the shape of semi-arc or similar shapes (not shown).

[0044] Figures 5a and 5b shows a second embodiment of the tensioning device 7 in a first open position and a second locked position. Here the tensioning device 7 is a lever 7a attached to and adapted to pivot around an eccentric support part 7b. The support part 7b is arranged to be in contact with the support plate 1 0, either directly or indirectly via a casing 14, and is arranged to pivot around an end 9a of the pin 9 connecting the tensioning device 7 and the locking plate 10. In order to minimize the friction forces between the support part 7b and the pin end 9a, the pin end 9a may have a spherical or semi-spherical shape adapted to easily slide in a corresponding spherical or semi-spherical cavity 7b 1 in the support part 7b. It is also possible that the tensioning device 7 pivots around a shaft (not shown) protruding horizontally through the cavity 7bl .

[0045] The eccentric support part 7a is so designed that when the lever 7a is in its first open position (fig 5a), it is a first distance d l between the center of the cavity 7b l and the support plate 10 and when the lever 7a is in its second closed position (fig 5b) it is a second distance d2 between the center of the cavity 7b 1 and the support plate 1 0. The first distance d l is less than the second distance d2. Thus, when pivoting the lever from its first to its second position, the distance between the support plate 1 0 and the locking plate 8 is decreased. This creates a bending force F on the locking plate 8 that firmly locks the locking arms 8a, 8b in the slots 1 2, 1 3.

[0046] !f the tensioning device 7 is acting against a casing 14, as shown in figures 5a and 5b, the casing 14 is preferably firmly attached to the frame 6. The casing 14 may have a surface 14' facing the tensioning device 7, having at least two recesses 14a arranged separated from each other in a direction parallel to the extension direction of the slots 1 2, 1 3. The recesses 14a are preferably shaped after the support part 7a of the lever, so that vertical movements of the locking plate 8, thus also the connected back support 5, is even further prevented when the tensioning device 7 is in its locked position.

Claims

1 . Adjustment device (2) for a chair ( 1 ) with a seat (3) and a back rest (4) comprising a frame (6) and a back cushion (5), wherein the adjustment device (2) is attached to the back cushion (5) and is adapted to slide in relation to the frame (6) to adjust the height of the back cushion in relation to the seat (3) and wherein the frame (6) or a support plate (1 0) attached to the frame (6) comprises a first and a second slot (1 2, 1 3) in which the adjustment device (2) is adapted to slide characterized in that the adjustment device (2) comprises a locking plate (8) having at least two locking arms (8a, 8b) protruding in opposite directions from first sides of the plate (8) transverse to the extension direction of the first and second slot ( 1 2, 1 3), and a tensioning device (7) adapted to create a force (F) on a surface (8') of the locking plate (8) acting in a direction essentially transverse to the surface (8'), wherein the locking arms (8a, 8b) are adapted to slide in the first and second slots (1 2, 1 3) when no force (F) is applied and to lock the locking arms (8a, 8b) in the slots (1 2, 1 3) when the force (F) is applied.

2. Adjustment device (2) according to claim 1 , wherein the tensioning device 7 is adapted to adjust a distance (x) between the frame (6) and/or the support plate (10) and the locking plate (8).

3. Adjustment device (2) according to claim 1 or 2, wherein the tensioning device (7) is attached to the locking plate (8) by means of a pin (9).

4. Adjustment device (2) according to claim 3, wherein the pin (9) is adapted to slide in an intermediate guidance slot (1 1 ) in the frame (6) and/or in the support plate (1 0), arranged between the first and the second slot ( 1 2, 1 3).

5. Adjustment device (2) according to any of the above claims, wherein the tensioning device (7) is a lever (7a) attached to and adapted to pivot around an eccentric support part (7b) which is arranged to, directly or indirectly, be in contact with the frame (6) and/or the support plate (10).

6. Adjustment device according to claim 5, wherein the eccentric support part (7b) is arranged to pivot around an end (9a) of the pin (9) connecting the tensioning device (7) and the locking plate (8).

7. Adjustment device according to claim 6, wherein the pin end (9a) has a spherical or semi-spherical shape adapted to easily slide in a corresponding spherical or semi-spherical cavity (7b) in the support part (7b).

8. Adjustment device (2) according to either of claims 5-7, wherein the eccentric support part (7b) is arranged to act against a casing (14) attached to the frame (6) and/or the support plate (10), wherein the casing (1 4) comprises a surface with at least two recesses arranged separated from each other in a direction parallel to the extension direction of the slots.

9. Adjustment device (2) according to claim any of the above claims, wherein the locking arms (8a, 8b) are protruding from the locking plate at an angle (a) in relation to the surface (8') of the locking plate (8).

10. Adjustment device (2) according to any of the above claims, wherein four locking arms (8a, 8a^', 8b, 8b') are protruding from the locking plate (8) and wherein the locking arms (8a, 8a^', 8b, 8b') are arranged at each corner of the locking plate (8).

1 1 . Adjustment device (2) according to any of the above claims, wherein the locking arms (8a, 8a^', 8b, 8b') are elastically connected to the plate.

1 2. Adjustment device (2) according to any of the above claims, wherein the locking plate (8) is made of a flexible material.