WO2018207065A1

WO2018207065A1 - Mechanism for controlling the force for tilting a backrest of a chair

Info

Publication number: WO2018207065A1
Application number: PCT/IB2018/053114
Authority: WO
Inventors: Riccardo BECCEGATO
Original assignee: L.I.M.A. Snc Di Riccardo Ed Elisa Beccegato
Priority date: 2017-05-08
Filing date: 2018-05-04
Publication date: 2018-11-15
Also published as: IT201700049605A1; EP3634180A1; EP3634180B1

Abstract

Mechanism (1) for controlling the force for tilting a backrest (2) of a chair (3) comprising a box structure (5) associated to a seat (4) and to which is articulated, and contrasting an elastic element (10, 20, 21), the backrest (2), the elastic element (10, 20, 21) is disposed along a longitudinal axis (X-X, X'-X') configured to take a first operative position (PI) and at least one second operative position (P2) and a stop device (13) associated to the box structure (5) and provided with a translatingly movable stop block (14), position adjusting means (15) being configured to selectively translate the stop block (14) from a rest position (P3) wherein said stop block (14) is decoupled from said elastic element (10, 20, 21) to at least one abutment position (P4) wherein said stop block (14) abuts against said elastic element (10, 20, 21), by disposing said elastic element (10, 20, 21) in said at least one second operative position (P2).

Description

"MECHANISM FOR CONTROLLING THE FORCE FOR TILTING A BACKRE ST OF A CHAIR"

* * * *

TECHNICAL FIELD

The present invention refers to a mechanism for controlling the tilt of a backrest of an office-type chair.

PRIOR ART

Many mechanisms and systems adapted to control and adjust the tension of a backrest of a chair or armchair, of an office- type, comprising a box structure which is associable to a seat to which is articulated, and contrasting an elastic element, the backrest, are known.

The known mechanisms and systems in order to find a widespread and advantageous use, must satisfy a dual need:

- they should offer a safe comfort and should be ergonomic in order to enable an user both of a slim and strong build to easily command it without an excessive effort;

- they should be simple to use and should be manufactured at a low cost.

It is known that these two needs are reciprocally contrasting .

Indeed, the known mechanisms in order to be ergonomic and offer comfort, in some embodiments, act on the preload of a spring and use systems adapted to thrust or pull a free end of the spring. Some other known systems adjust an axial load applied to the spring by rotating an adjusting knob or by using rack-and-pinion systems for moving the spring to plural discrete positions. A known solution is described in the European patent application No. 0592008A1 in the name of Herman Miller, Inc. regarding a mechanism for adjusting the tilt and height of a chair. Further solutions are described in the International Application No. WO 2010/028412A1 in the name of Bene AG and in the patent application No. DE102007040175B3 in the name of Bock 1 GmbH & Co. KG, regarding respective devices adapted to adjust the opposing force of a chair backrest. Even though the known mechanisms are advantageous from different aspects, they exhibit some inconveniences such as for example the structural complexity which, besides being determined and constrained by the spatial arrangement imposed to the several components, must be kept inside the box structure.

Moreover, the rotation knob of some devices used for obtaining displacements of a desired amount, requires the users to apply a substantial and prolonged physical effort, in order to transform a rotation force in an axial thrusting force. Therefore, such solutions are not easy to be activated.

The technical problem underlying the present patent application consists of devising a mechanism for controlling the tilt of a backrest of office-type chairs, which enables to satisfy the comfort and is ergonomic, safe and lightweight, so that can be used by different types of users without applying a particular effort, compact and manufacturable at a low cost and having structural and operative features enabling to satisfy the required needs, overcoming the drawbacks cited with reference to the known art.

Brief summary of the invention

The solving idea underlying the present patent application consists of providing a snap-type command of the elastic element without jeopardizing the desired adjusting and comfort features.

Based on such solving idea, the technical problem is solved by a control mechanism as defined in claim 1.

Further preferred embodiments of the mechanism are described in the dependent claims.

An embodiment provides a control mechanism having a box structure associated to a seat and to which is articulated, and contrasting an elastic element, the backrest, the elastic element being disposed along an axis and being configured to take a first operative position and at least one second operative position; a stop device being associated to the box structure and comprises a movable stop block configured to interact with the elastic element; means for adjusting the position being associated to the stop device and being configured to selectively translate the stop block from a rest position to at least one abutment position wherein the stop block limits the axial arrangement of the elastic element along the axis by disposing the elastic element in said at least one second operative position.

Advantageously, the stop device is configured to translate the stop block along a direction substantially normal to the axis.

Moreover, the stop block is disposed inside the box structure and has a parallelepiped shape exhibiting a pin axially protruding from a lateral face. The position adjusting means comprise a command rod coupled to the stop block, and laterally protruding from the box structure.

Advantageously, the command rod is configured to enable to be integrally translatingly coupled to the command rod. In an embodiment, it comprises an axial hollow configured to tightly receive the pin of the stop block.

The adjusting means suitably comprise an abutment element interposed between the stop block and command rod, and adapted to enable to be axially coupled to the command rod.

Advantageously, the elastic element comprises a first fixed coil spring disposed along an axis, and a second coil spring having at least one unconstrained end, the second coil spring being disposed along a second further axis parallel to the axis, the first coil spring and second coil spring being disposed side-by-side and being axially interposed between an oscillating pin and a front transversal wall of the box structure, the oscillating pin being transversally associated to respective lateral walls of the box structure, the backrest being articulated and coupled to the lateral walls by a transversal rotation pin.

Moreover, a supporting spacer is made by a hollow body having a substantially parallelepiped shape, the spacer comprises a supporting wall provided with a hole comprising a housing element configured to house the unconstrained end of the second coil spring.

Advantageously, the stop block is disposed inside the spacer and is movable from a rest position, wherein the stop block is interposed between the lateral wall and the hole of the spacer, to at least one abutment position wherein the stop block at least partially covers the hole, the stop block limiting the axial stroke of the second coil spring.

A further embodiment comprises a command body adapted to actuate a gas spring associated to the seat, the command body having a hollow frusto-conical shape tapered towards a free end, the command body being externally rotatively associated to the command rod protruding from the free end.

The command body suitably comprises a command projection externally radially protruding from an opposite end, the flange being provided with a hole adapted to enable to couple a lever element protruding from an opening present in the lateral wall of the box structure, the lever element being configured to activate an actuation button of the gas spring.

Brief description of the drawings

Further characteristics and advantages of the invention will better appear from the following description of a preferred embodiment of the mechanism and variants thereof exemplifyingly provided with reference to the attached drawings, wherein:

- Figure 1 is a perspective view of a schematic embodiment of the mechanism, provided according to the present invention, coupled to a seat and to a backrest of a chair, these latter being illustrated by a broken line;

- Figure 2 shows a plan top view of the mechanism of

Figure 1 ;

Figure 3 is an exploded perspective view of the mechanism of Figure 2;

Figure 4 illustrates a cross-section view of the mechanism of Figure 2, the cross -section being made along a cross-section plane A-A, the stop block being in a rest position;

- Figure 5 illustrates a cross-section view analogous to the one of Figure 4, the mechanism with the stop block being in an abutment position;

- Figures 6 and 7 illustrate views analogous to Figures 2 and 3, of a further embodiment of the mechanism according to the present invention.

Detailed description

With reference to the attached figures, a control mechanism, according to the present invention, is generally indicated by the number 1 and is coupled to a chair 3 or an armchair of an office-type, partially shown by a broken line and comprising a seat 4 and an oscillating backrest 2. The control mechanism 1 enables to control the force for tilting the backrest 2.

The mechanism 1 comprises a box structure 5 associated to the seat 4 by a connecting plate 5a, and to which is articulated, and contrasting an elastic element 10, the backrest 2.

According to an embodiment, the box structure 5 comprises a substantially rectangular bottom 5b provided with two longitudinal lateral walls 6a and 6b, and with at least one front transversal wall 6c interposed between said lateral walls 6a and 6b. The box structure 5 is provided with a mouth 8 for connecting a stem comprising a conventional gas spring, not shown in the figures.

The oscillating backrest 2 comprises at least one hooking bracket 7 associated to the mechanism 1.

The hooking bracket 7 exhibits the curved ends 7a and 7b, articulated and coupled to said respective lateral walls 6a and 6b, by a transversal rotation pin 9a. The rotation pin 9a is through at a pair of holes made on said curved ends 7a and 7b, and is rotatively associated to the lateral walls 6a and 6b, housed in respective holes.

The elastic element 10 is disposed in said box structure 5 along a substantially longitudinal axis X-X. The elastic element 10 exhibits an end coupled to an oscillating pin 9b, and an opposite end coupled to the transversal wall 6c. According to an embodiment, the oscillating pin 9b is transversal to the lateral walls 6a and 6b, and is disposed parallel to the rotation pin 9a and is integrally oscillating with the curved ends 7a and 7b of the hooking brackets 7.

A stop device 13 is associated to the box structure 5 and is configured to stop the axial position of the elastic element 10 along the longitudinal axis X-X.

Means 15 for adjusting the position are associated to said box structure 5 and are configured to command the stop device 13 so that the elastic element 10 has:

- at least one first operative position PI in which at least one end thereof is unconstrained, in other words axially movable along the longitudinal axis X-X for any oscillations of the backrest 2;

- a second operative position P2 wherein the unconstrained end is coupled to the stop device 13.

According to an embodiment, the stop device 13 is interposed between the elastic element 10 and the transversal wall 6c.

The stop device 13 comprises a movable stop block 14 associated and selectively actuated by said position adjusting means 15. The stop block 14 substantially defines an axial stroke limiter of said elastic element 10 and interacts with the movable end in order to block the axial position of the elastic element 10 in at least said prefixed operative position P2.

The position adjusting means 15 are configured to selectively translate the movable stop element 14 from a rest position P3 (Figure 4), wherein the stop block 14 is decoupled from said elastic element 10, to at least one abutment position P4 (Figure 5) wherein the movable stop block 14 is coupled to the movable end of the elastic element 10 and the elastic element 10 is disposed in said at least one second operative position P2.

The movable stop block 14 is translated along a direction Y-Y which is substantially normal to the longitudinal axis X- X of said elastic element 10.

In an embodiment, illustrated in the attached figures, the elastic element 10 comprises a first coil spring 20 and a second coil spring 21 disposed side-by-side and interposed between the oscillating pin 9b and the front transversal wall 6c .

The first coil spring 20 and second coil spring 21 are coupled to the oscillating pin 9b respectively by a first bushing 22 and second bushing 23. Preferably, the first bushing 22 and second bushing 23 are fixed to a supporting rod 24 coupled to the oscillating pin 9b. In an embodiment, the first bushing 22, second bushing 23, and supporting rod 24 are made in one piece.

The first coil spring 20 is disposed along the longitudinal axis X-X and the second coil spring 21 is disposed along a further axis X'-X' substantially parallel to the longitudinal axis X-X of the first coil spring 20.

The first coil spring 20 exhibits the end 20a which is associated to the first bushing 22 fixed to the oscillating pin 9b and an opposite end 20b associated to a third bushing 26 which is preferably fixed to a supporting spacer 25.

The second coil spring 21 exhibits the end 21a coupled to the second bushing 23 fixed to the oscillating pin 9b and exhibits an unconstrained movable end 21b defining the unconstrained end of the elastic element 10.

A fourth bushing 27 is coupled to the unconstrained end

21b of the second coil spring 21.

In an embodiment, the fourth busing 27 is in the shape of a mushroom having a substantially circular head 27a and a stem 27b comprising lateral ribs 27c.

The supporting spacer 25 is comprised in said stop device

13 and is defined by a hollow body having a substantially parallelepiped box shape, comprising at least one supporting wall 25a which connects a lower base wall 25c to an upper base wall 25b. Particularly, the lower base wall 25c is fixed to the bottom 5b of the box structure 5. The lower base wall 25c and upper base wall 25b are abuttingly coupled to the transversal wall 6c of the box structure 5.

The third bushing 26 is fixed to the supporting wall 25a, while the fourth bushing 27 is housed in a hole 28 provided on the supporting wall 25a. The hole 28 is provided with a first and second curved fins 29a and 29b perimetrally protruding from the same part of said third bushing 26 and defining a housing element 29, in other words a chamfered and guiding element for the second coil spring 21. In an embodiment, the stop device 13 exhibits the stop block 14 being in a substantially parallelepiped shape having a pin 14b axially protruding from a lateral face 14a. The stop block 14 is at least partially inserted inside the spacer 25 abutting against the lower base portion 25c and is interposed between the lateral wall 6b of the box structure 5 and the hole 28 provided on the support wall 25a.

The position adjusting means 15 are axially mounted, along the direction Y-Y, on a command rod 40 laterally protruding from the lateral wall 6b of the box structure 5.

The command rod 40 is coupled to the stop block 14 by a hole 38 made on the lateral wall 6b and is disposed at the spacer 25.

In an embodiment, the command rod 40 has a frusto-conical shape from an end 43 proximal to the lateral wall 6b to a distal end 44. An axial hollow 42 is made from the proximal end 43. The command rod 40 is actuatable by the user for selectively axially translating the stop block 14. The adjusting means 15 comprise an abutment element 35 interposed between the stop block 14 and command rod 40. The abutment element 35 comprises a base plate 36 and a bushing 37 coupled perpendicularly to the base plate 36. The base plate 36 is coupled inside the box structure 5, the bushing 37 protruding from the hole 38.

According to an embodiment, the command rod 40 exhibits the first portion 41 axially inserted in the bushing 37, while the pin 14b of the stop block 14 is tightly inserted in the hollow 42 for obtaining a mechanical coupling. Consequently, the pin 14b defines an element for centering the command rod 40, while the abutment element 35, since interacts with the box structure 5, enables to hold the command rod 40 in the direction Y-Y substantially normal to the axis X'-X' of the second coil spring 21.

The movable stop block 14 is translatingly integral with the moving command rod 40 actuatable by the user. The stop block 14 axially slides along the direction Y-Y inside the spacer 25 from the rest position P3, illustrated in Figure 4, wherein the stop block 14 is interposed between the lateral wall 6b and perimetral edge of the hole 28 to at least one abutment position P4 wherein the stop block 14 is translated along the direction Y-Y, occupying at least partially the hole 28 with a lateral face 14c. The stop block 14 abuts against the fourth bushing 27 and limits the stroke of the unconstrained end 21b, stopping the second coil spring 21 in said second operative position P2.

The operative principle of the mechanism 1 for controlling the force for tilting the backrest, is illustrated in the Figures 4 and 5.

Figure 4 illustrates the mechanism 1, the elastic element

10 being in the first operative position PI, wherein the first coil spring 20, oscillating integrally with the oscillating pin 9b, has the ends constrained and operates in an compressed state, providing the user, which backwardly thrusts the oscillating backrest 2, a first return force. In this case, the stop block 14 is disposed in said rest position P3, in other words in a position proximal to the lateral wall 6b of the box structure 5, and the command rod 40 of the position adjusting means 15 is distal from the lateral wall 6b. The second coil spring 21 is in a rest condition, in other words the unconstrained end 21b is housed inside the housing element 29 of the hole 28 and, when the backrest 2 is tilted, is substantially "idle" freely axially movable inside the hole 28 without providing a resistance or anyway increasing the first return force of the first coil spring 20.

Figure 5 illustrates the mechanism 1 with the elastic element 10 in the second operative position P2. The command rod 40, actuated by the user, is thrusted inside the box structure 5 along the direction Y-Y, axially translating the stop block 14 in the abutment position P4. The stop block 14 occupies at least partially the block 28 and actually stops the head 27a of the fourth bushing 27, defining a stroke limiter for the unconstrained end 21b of the second coil spring 21. Consequently the elastic element 10 is in the second operative position P2 wherein the first coil spring 20 and second coil spring 21 are constrained in their positions and operate in a compressed state.

Therefore, the mechanism 1 provides the user, which backwardly thrusts the backrest 2, a second return force greater than the first return force because it is increased by the force provided by the second coil spring 21 disposed in the operative position.

The Applicant has found that the requirements of the majority of the users are also satisfied by only two selectable values of the return force developed by the mechanism according to the present invention, .

Now, particularly referring to the example illustrated in Figures 6 and 7, an embodiment variant of the present invention is described in which cooperating features and portions having the same structure and function as the ones of the previous embodiment example will be indicated by the same numerals and reference marks.

Particularly, the control mechanism 1 comprises a command body 30 adapted to actuate a gas spring associated to the seat 4 and configured to adjust the height of the seat 4.

The command body 30 is in a frusto-conical hollow shape and tapered towards a free end 31. The command body 30 is outwardly rotatively coupled to the command rod 40.

The command body 30 is axially inwardly provided with ribs 32 for abutting the command rod 40, which protrudes from the free end 31 with at least the distal end 44 which, in an embodiment, exhibits a button shape.

The command body 30 comprises a command projection 33 radially protruding from the free end 31, which is adapted to be clockwise actuated by the user. Moreover, the command body 30 comprises a flange 46 outwardly radially protruding from the opposite end 34, which is provided with a slit-shaped hole 46a.

The flange 46 is laterally associable to the lateral wall 6b at a slit-shaped opening 39 for being interconnected to a lever element 47, partially illustrated in Figure 6. The lever element 47 is adapted to activate an actuation button of the gas spring, not illustrated in the figures, enabling to rise and lower the seat 4.

In such embodiment, the command body 30 defines an element containing and protecting the adjusting means 15 of the stop device 13, and also helps axially support the command rod 40. Further, the control mechanism 1, implemented in this way, is substantially compact and sturdy, moreover enables to separately and independently control the force for tilting the backrest 2 and the height of the seat 4.

Actually, the materials useable for making the control mechanism, and also the dimensions, characteristics of the elastic element or the fixing systems for the box structure, could be of any type according to the requirements.

It is noted that the mechanism devised in this way, meets the prefixed tasks and objects because the same is user- friendly and actuatable by the command rod by simply exerting a thrusting action towards the box structure, or towards the outside of the chair, enabling to modify the force for tilting the seat, consequently meeting the particular needs of the user.

Moreover, the mechanism exhibits a substantial ergonomics since is provided with a command for an easy and fast adjustment. In addition, the mechanism, in virtue of the shape of the stop device and of the position adjusting means, exhibits a substantial manufacturing simplicity obtainable at a low cost with respect to the more complicated known mechanisms .

Further, the adjusting means according to the present invention provide a compact user-friendly mechanism having also an attractively pleasant appearance.

Obviously, the mechanism lends itself to several modifications and variants all falling into the scope of the inventive step. So, for example the elastic element can comprise three coil springs disposed side-by-side, the axes thereof being parallel to each other, the stop block can be provided with two small blocks selectively sequentially actuatable by the same button or by buttons or knobs.

Further, all the details can be substituted by other technically equivalent elements.

Claims

C LAI MS

1. Mechanism (1) for controlling the force for tilting a backrest (2) of a chair (3) comprising a box structure (5) associated to a seat (4) to which is articulated, and contrasting an elastic element (10, 20, 21), the backrest (2),

- the elastic element (10, 20, 21) is disposed along to a longitudinal axis (X-X, X'-X') and

- a stop device (13) is associated to said box structure (5) and is configured to interact with said elastic element (10, 20, 21);

characterized in that:

- the elastic element (10, 20, 21) is provided with a first operative position (PI) and with at least one second operative position (P2);

- the stop device (13) is provided with a translatingly movable stop block (14);

position adjusting means (15) are configured to selectively translate said stop block (14) from a rest position (P3) wherein said stop block (14) is decoupled from said elastic element (10, 20, 21) to at least one abutment position (P4) wherein said stop block (14) abuts against said elastic element (10, 20, 21) in order to limit the axial arrangement of said elastic element (10, 20, 21) along said longitudinal axis (X-X, X'-X') and arrange said elastic element (10, 20, 21) in said at least one second operative position (P2) .

2. Mechanism (1) according to claim 1, characterized in that said stop device (13) is configured to translate said stop block (14) along a direction (Y-Y) substantially normal to said longitudinal axis (X-X, X'-X') .

3. Mechanism according to claim 1, characterized in that said stop block (14) and said position adjusting means (15) exhibit a translatingly integral coupling.

4. Mechanism according to claim 3, characterized in that said position adjusting means (15) comprise a command rod (40) coupled to said stop block (14) and laterally protruding from said box structure (5) .

5. Mechanism according to claim 4, characterized in that said command rod (40) comprises an axial hollow (42) configured to tightly receive a pin (14b) coupled to said stop block (14) adapted to enable said translatingly integral coupling with said command rod (40) .

6. Mechanism according to claim 5, characterized in that said stop block (14) has a parallelepiped shape, said pin (14b) axially protruding from a lateral face (14a), said stop block (14) being disposed inside said box structure (5) .

7. Mechanism according to claim 6, characterized in that said adjusting means (15) comprise an abutment element (35) interposed between said stop block (14) and said command rod (40) configured to enable to axially couple said command rod (40) to said box structure (5) .

8. Mechanism according to claim 7, characterized in that said abutment element (35) comprises a base plate (36) and a bushing (37), said base plate (36) being coupled inside the box structure (5) and said bushing (37) being perpendicularly coupled to said base plate (36) and protruding outside said box structure (5) .

9. Mechanism according to claim 1, characterized in that said elastic element (10, 20, 21) comprises parallel side-by- side first and second coil springs (20, 21) .

10. Mechanism according to claim 9, characterized in that it comprises said first fixed coil spring (20) disposed along the longitudinal axis (X-X) , and said second coil spring (21) disposed along a further axis (Χ'-Χ') with at least one unconstrained end (21b), said stop block being adapted to interact (13) with said unconstrained end (21b) .

11. Mechanism according to claim 10, characterized in that it comprises said first coil spring (20) and said second coil spring (21) axially interposed between an oscillating pin (9b) and a front transversal wall (6c) of a spacer (25) associated to said box structure (5), said oscillating pin (9b) being transversally associated to respective lateral walls (6a and 6b) of said box structure (5), said backrest (2) being articulated and coupled to said lateral walls (6a and 6b) by means of a transversal rotation pin (9a) .

12. Mechanism according to claim 11, characterized in that said supporting spacer (25) is a hollow body having a substantially parallelepiped shape, said spacer (25) comprising a supporting wall (25a) provided with a hole (28) with a housing element (29) configured to house said unconstrained end (21b) of said second coil spring (21) .

13. Mechanism according to claim 12, characterized in that said stop block (14) is disposed inside said spacer (25) and is movable from said rest position (P3), wherein said stop block (14) is interposed between said lateral wall (6b) and said hole (28) of said spacer (25), to said at least one abutment position (P4) wherein said stop block (14) covers at least partially said hole (28), said stop block (14) limiting the axial stroke of said second coil spring (21) .

14. Mechanism according to claim 5, characterized in that it further comprises a command body (30) adapted to actuate a gas spring associated to said seat (4), said command body (30) having a frusto-conical hollow shape tapered towards a free end (31), said command body (30) being associated outwardly and rotatively to said command rod (40) protruding from said free end ( 31 ) .

15. Mechanism according to claim 14, characterized in that said command body (30) comprises a command projection

(33) radially protruding from said free end (31) and a flange (46) protruding outwardly and radially from an opposite end

(34) , said flange (46) being provided with a hole (46a) adapted to enable to couple a lever element (47) protruding from an opening (39) present in said lateral wall (6b) of said box structure (5), said lever element (47) being configured to actuate an activation button of said gas spring.