EP3468416B1

EP3468416B1 - Articulation system for chairs

Info

Publication number: EP3468416B1
Application number: EP17733891.0A
Authority: EP
Inventors: Sergio Moreschi
Original assignee: CO FE MO Industrie Srl
Current assignee: CO FE MO Industrie Srl
Priority date: 2016-06-10
Filing date: 2017-05-23
Publication date: 2021-06-09
Anticipated expiration: 2037-05-23
Also published as: EP3903642B1; EP3903642A1; BR112018075328A2; EP3468416A1; ITUA20164261A1; WO2017212361A1

Description

The present invention refers to an articulation system for chairs, particularly of the type in which the movements of the seat and backrest are synchronized with respect to each other.
There are prior-art chairs, particularly office chairs, which comprise an articulation system comprising a main frame constrained to a base for resting the chair on the ground, a support for the seat and a support for the backrest of the chair. The support for the seat and the support for the backrest are both articulated with respect to the frame and, owing to an articulation mechanism that connects them, they are articulated with respect to each other so that a movement of one corresponds to a predetermined movement of the other (this articulation mechanism is defined as "synchronized" in the technical jargon of this field). In certain solutions, the articulation mechanism connecting the two supports is adjustable so that the relation between the two movements can be changed.
When one of the two supports is moved by pressure exerted by the user, the system resists with an elastic reaction that tends to return both supports back to the at-rest configuration (that is, without any pressure being applied). This reaction is typically obtained by means of an elastic element, for example at least one spring.
WO 2009/153811 A1 discloses an adjustment device for chairs, comprising a main body, which can be engaged onto a supporting shank of a chair; a prop element mounted on the main body; a backrest mounted onto the main body; and articulation means for movably engaging the backrest and the seat support to the main body, the articulation means comprising a lever pivoting around the main body and hinged to the prop element and to the backrest so as to obtain a given relation of movement between the backrest and the prop element.
WO 2010/097818 A1 discloses a device for synchronizing the inclination of the backrest and seat of a chair, of the type comprising a frame for the backrest, a frame for the seat and a support integral with the base of the chair, as well as a first crank integral with the frame for the backrest and hinged to the rear part of the frame for the seat and to the support, and a second crank hinged to the front part of the frame for the seat and to the support, so as to form, together with the frame for the seat, an articulated quadrilateral. The Applicant has found that the prior-art articulation systems for chairs have several drawbacks and/or that several aspects thereof can be improved.
For example, the Applicant has noted that because of their structures being based on levers or cranks pivoted to the main frame, the articulation systems of WO 2009/153811 A1 and WO 2010/097818 A1 determine a rotational-translational movement of the seat in which the vertical and horizontal components of the translational motion of the front part of the seat are rigidly determined. In particular, the Applicant has observed that the front hinge point of the seat completes an arc of a circle with the centre facing the rear part of the system, and this, given a certain relation between the vertical component and the horizontal component of the translational motion of the front part of the seat in the initial tract of the movement, determines a modification of this relation in the course of the movement, becoming increasingly imbalanced in favour of the horizontal component to the disadvantage of the vertical component. In particular, the elevation rate of the front part of the seat as a function of the rotation of the backrest proves to gradually decrease upon an increase in the degree of inclination of the backrest with respect to the at-rest position. This leads to the fact that the effect of the user's weight on the seat, which tends to resist inclination, tends to decrease upon an increase in the inclination of the backrest, to the point that the effect is eliminated, and potentially change direction when having greater inclinations.
According to the Applicant once again, this pattern brings about a response to the inclination perceived by the user that is not always optimal for the entire course of travel for the inclination, and/or it brings about limitations in the measure of the inclination of the backrest and/or chair.
An aim of the present invention is to develop an articulation system for chairs which resolves one or more of the issues described above.
This aim is achieved by an articulation system for chairs in accordance with the appended claims and/or having the following characteristics.
According to a first aspect, the invention refers to an articulation system for chairs, the system comprising:

a main frame designed to be associated with a base for a chair;
a support for a seat mounted on said main frame;
an articulation element that is rigid and hinged to said main frame so that it can rotate about an axis of rotation, wherein said support for the seat is hinged to said articulation element at a first hinge point;
a support for a backrest coupled to said articulation element;
a slider that is slidably movable along a guide solidly constrained to said main frame,

In accordance with a further aspect, the present invention concerns a chair comprising the articulation system in accordance with the first aspect.
The terms vertical, horizontal, upper, lower and suchlike refer to a state of normal use of a chair that incorporates the articulation system of the present invention.
The terms front and rear refer to normal use of a chair that incorporates the present invention, in which the user's legs are at the front side of the system.
According to the Applicant, the systems for synchronized articulation of a backrest and seat disclosed in WO 2009/153811 A1 and WO 2010/097818 A1 , which utilize rods for articulating the seat and main body, are such that the front hinge point of the seat is forced to travel, in the reference plane, a path in the form of an arc of a circle with the concavity facing the axis of rotation of the rear articulation rod.
This movement of the front hinge point constitutes a mechanical constraint that creates an upper dead centre of the path of the hinge point, in which the latter moves almost horizontally, and/or predetermined dynamics of variations in the relation between the vertical and horizontal component of the translational motion of the front part of the seat. This, in turn, brings about functional limits in the overall articulation system, for example of the type described hereinabove.
However, owing to the articulation of the front part of the seat and the main frame with the guide and slider, wherein the slider can follow a path along the guide, said path being at least partially curvilinear with the concavity facing the other side of the point of rotation of the articulation element, the present solution produces a movement of the front part of the seat without any upper dead centres.
In this manner, the measure of the range of inclination and/or the maximum degree of inclination that can be reached by the backrest can be increased.
The present solution also makes it possible to maintain a desired elevation rate for the front part of seat as a function of the rotation of the articulation element, for the entire course of travel for the rotation of the latter.
The development of this elevation rate depends on the specific design of the guide.
For example, for curvilinear guides, the relation between the horizontal and vertical components develops in an opposite manner compared to the development obtained in the case of articulation with a front lever or crank (that is, in the form of an arc of a circle with the concavity facing rearwards). For example, this elevation rate can increase upon an increase in the rotation of the articulation element.
Moreover, according to the Applicant, without being bound to any theory, and with respect to the above-mentioned solutions of the prior art, the above-mentioned characteristics determine a different resolution of the elastic reaction force acting upon the second hinge point of the seat, with effects that are advantageous in terms of the response of the articulation system to inclination as a function of the degree of inclination and/or the user's weight.
In one or more of the above-mentioned aspects, the present invention can have one or more of the following preferred characteristics, some of which refer to the above-mentioned reference plane.
Said path section typically coincides with the entire path possible for said second hinge point.
Preferably, said curvilinear path section extends along (or approximates) an arc of a circle having a centre, wherein a horizontal line passing through said centre remains above the path section and a vertical line passing through the centre remains in front of the path section.
Said arc of a circle preferably has a radius greater than or equal to 50mm, more preferably greater than or equal to 60mm, and/or less than or equal to 200mm, preferably less than or equal to 150mm.
The Applicant has found that these characteristics of the curvilinear section give the second hinge point advantageous movement properties. For example, the rate of elevation of the second hinge point tends to increase in the upper portion of the path (corresponding to more accentuated inclinations of the backrest), to the disadvantage of the horizontal translation component of the second hinge point.
These movement properties (which are possibly combined with the particular dynamics of transmitting the above-described reaction force to the supports) offer advantageous effects to the chair considered in its entirety, in terms of the response to the inclination perceived by the user.
The first hinge point is preferably located in a rear portion of the support for the seat. The structure thus proves to be compact.
The system is preferably configured to assume an at-rest configuration in the absence of tilting forces acting upon the support for the seat and/or backrest. In this at-rest configuration, when the seat is fixed on the support for the seat, the seat is typically arranged horizontally and when the backrest is fixed to the support for the backrest, the backrest is substantially vertical.
The system is preferably configured to assume a maximum inclination configuration, in which the support for the seat and the support for the backrest assume the maximum inclination possible with respect to the at-rest position.
Said guide typically has a lower end, which typically has a lower abutment surface, and an upper end, which typically has an upper abutment surface, wherein in the at-rest configuration and in the maximum inclination configuration, the slider is found at the lower and upper end of the guide, respectively, preferably abutting against said lower and/or upper abutment surface, respectively. Advantageously, the guide thus also acts as a stopping point.
In one embodiment, in said at-rest configuration, the first hinge point is found, with reference to said reference plane, interposed between a line vertical to said axis of rotation and a line vertical to the second hinge point, and preferably above a line horizontal to the axis of rotation. In this manner, the articulation system opposes a reaction to the inclination proportional to the weight of the user on the seat (called "self-weighing" in the jargon of this field). In fact, when the user exerts pressure (typically on the backrest), which tends to make the seat tilt by rotational-translational movement of the seat starting from the at-rest configuration, the first hinge point must necessarily rise, thereby overcoming a component of the weight of the user.
According to the Applicant, in this embodiment the fact that said path section is curvilinear as described above is particularly advantageous.
In an alternative embodiment, in said at-rest configuration, the first hinge point is found, with reference to said reference plane, on the opposite side of a line vertical to said axis of rotation with respect to the second hinge point, and preferably above a line horizontal to the axis of rotation.
In this manner, the weight force of the user (particularly when the user shifts his/her weight rearward) contributes to the tilting process, although the concomitant rearward movement of the seat opposes this tilting process, owing to the presence of the forces of friction between the user and the seat.
In one embodiment, the support for the backrest is solidly constrained to said articulation element. For example, the articulation element can form one whole element with at least one part of said support for the backrest or the support for the backrest can be rigidly fixed to the articulation element. In this manner, the system in its entirety proves to be simple in construction, reliable and economical in terms of production.
In one alternative embodiment, the support for the backrest is connected to the articulation element in an articulated manner. In this manner, additional degrees of freedom are introduced between the backrest and the seat, leading to improved ergonomics and/or versatility and/or comfort of the chair.
In the above-mentioned alternative embodiment, the articulation system preferably comprises an additional articulation element that is rigid and hinged to said main frame so that it can rotate about an additional axis of rotation, wherein said support for the backrest is hinged to said articulation element on a side of the articulation element that is opposite said first hinge point of the seat with respect to said axis of rotation, and it is also hinged to said additional articulation element.
The articulation system preferably comprises at least one elastic element that is operatively interposed between said main frame and said support for the seat. In this manner, the elastic reaction force developed by the elastic element opposes inclination of the seat with respect to an at-rest state, typically in a more pronounced manner the more accentuated the inclination is.
Preferably, on one side said elastic element directly abuts against the main frame and on the opposite side against the hinge point and/or the support for the seat. The system thus proves to be structurally simple, rational and effective. Said elastic element is preferably configured to work in extension.
The chair preferably comprises a supporting base for resting the chair on the ground and a rod mounted on the supporting base for resting the chair on the ground, said main frame being rigidly mounted onto an upper end of said rod.
The chair preferably comprises a seat for a user that is rigidly coupled to said support for the seat and/or a backrest rigidly coupled to said support for the backrest.
The characteristics and advantages of the present invention shall be clarified further in the following detailed description of some embodiments, which are presented as nonlimiting examples of the present invention, with reference to the attached figures, of which:

Figure 1 is a schematic side view of a system according to a first embodiment of the present invention in an at-rest configuration;
Figure 2 is a schematic side view of the system of Figure 1 in a maximum inclination configuration.

An articulation system 1 for chairs according to the present invention is shown in the figures. For the purposes of providing a concise description, the same reference numbers are used for corresponding elements in the various embodiments.
The articulation system 1 comprises a main frame 2, which is for example designed to be rigidly mounted onto an upper end of a rod 3 mounted on a base not shown) for resting a chair on the ground.
The articulation system 1 further comprises a support for the seat 4 and a support for the backrest 5, both of which are mounted on the main frame in an articulated manner.
The finished chair typically comprises a seat 6 that is rigidly coupled to the support for the seat 4 and a backrest 7 that is rigidly coupled to the support for the backrest 5.
The articulation system further comprises an articulation element 8 that is rigid and hinged to the main frame so that it can rotate about an axis of rotation 9.
At the rear, the support for the seat 4 is hinged to the articulation element 8 at a first hinge point 10 preferably located at the rear of the seat, and at the front it is hinged at a second hinge point 11 located at the front of the seat to a slider 12 that is slidably movable along a guide 13 solidly constrained to the main frame 2.The present invention also envisages solutions in which the first hinge point is located in a central position of the support for the seat or in a front position.
In the examples shown, the slider 12 is a cylindrical pin solidly constrained to the support for the seat 4 and which, at the longitudinal ends thereof, engages a pair of guides 12 that are symmetric with respect to each other, the guides 13 being through openings afforded in the main frame 2.
With reference to a reference plane perpendicular to the axis of rotation (for example the same lying plane of the figures), the guide 13 determines a path for the front hinge point 11 having at least one curvilinear section 14 with the concavity facing away from the axis of rotation 9 (as shown in Figures 1 and 2).
The articulation system 1 typically comprises at least one elastic element 20 (only schematically illustrated), for example a spring that is operatively interposed between the main frame 2 and the support for the seat 4, so as to oppose inclination of the seat with respect to the at-rest state, in a more pronounced manner the more accentuated the inclination is.
The elastic element can directly abut against the main frame on one side and, on the other side, against the first and/or second hinge points and/or against the support for the seat and/or against the support for the backrest.
In Figure 1, the system 1 is illustrated in an at-rest configuration, in the absence of tilting forces acting on the support for the seat and/or the backrest (or when these tilting forces do not surpass a possible preload force of the elastic element). In this at-rest configuration, the seat 6 is typically arranged horizontally and the backrest 7 is substantially vertical.
In Figure 2, the system 1 is illustrated in a maximum inclination configuration, in which the support for the seat and the support for the backrest assume the maximum inclination possible with respect to the at-rest position.
In the examples shown, the path section 14 coincides with the entire path possible for the front hinge point 11.
Advantageously, the system can provide a stopping point for the inclination process, at the abutment of the slider 12 against an upper abutment surface 22 of the guide or when the line joining the first and the second hinge point becomes perpendicular to the tangent to the path at the front hinge point (a state beyond which the articulation element cannot rotate further).
The guide preferably has a lower abutment surface 21, where, in the at-rest configuration, the slider 12 is found at the lower abutment surface.
In the embodiments illustrated in Figures 1-2, the support for the backrest 5 forms one whole element (i.e. a single piece) with the articulation element 8. Alternatively, the support for the backrest can be separate from the articulation element, but rigidly fixed to the latter.
In an alternative embodiment, which is not illustrated here, the support for the backrest is connected to the articulation element in an articulated manner, and in a manner similar to the articulation of the support for the backrest with respect to the main frame and to the support for the seat disclosed in patent WO 2009/153811 A1 cited hereinabove, to which the reader is referred for further information.
Referring to the embodiment in Figures 1 and 2, in the at-rest configuration, the first hinge point 10, in the reference plane, is interposed between a line 30 vertical to the axis of rotation 9 and a line 31 vertical to the front hinge point 11, and above a line 32 horizontal to the axis of rotation.
In this example embodiment, the path section 14 is curvilinear and extends along an arc of a circle having a centre 40 located above and in front of the path section. By way of example, the arc of a circle has a radius equal to about 87 mm.
In this embodiment, in passing from the at-rest configuration to the maximum inclination configuration, the seat rotationally translates in such a manner that both the rear part and the front part are lifted and move rearward. Advantageously, the relation between the elevating movement and the rearward movement of the front part varies as a function of the inclination, wherein in the final section of the movement, the elevating movement plays a greater role with respect to the beginning of the movement.
Additionally, the present invention also envisages solutions (not shown) in which the curvilinear path section is combined with a relative arrangement between the first hinge point and the line 30 vertical to the axis of rotation.
Furthermore, the present invention also envisages solutons (not shown) in which in addition to the above-mentioned curvilinear path section, the possible entire path also comprises additional sections that may be rectilinear, or additional curvilinear sections with the concavities thereof facing the axis of rotation.

Claims

An articulation system (1) for chairs, the system comprising:
- a main frame (2) designed to be associated with a supporting base for resting a chair on the ground;

- a support for a seat (4) mounted on said main frame;

- an articulation element (8) that is rigid and hinged to said main frame (2) so that it can rotate about an axis of rotation (9), wherein said support for the seat (4) is hinged to said articulation element (8) at a first hinge point (10);

- a support for a backrest (5) coupled to said articulation element (8);

- a slider (12) that is slidably movable along a guide (13) solidly constrained to said main frame,
wherein said support for the seat (4) is hinged to said slider (12) at a second hinge point (11) located in a front portion of the support for the seat,
wherein in a reference plane perpendicular to said axis of rotation (9), said guide (13) determines a path for said second hinge point (11),
characterised in that said path has at least one path section (14) that is curvilinear with the concavity facing away from said axis of rotation (9).
The articulation system according to claim 1, wherein said path section (14) coincides with an entire path possible for said second hinge point (11).
The articulation system according to any one of the preceding claims, wherein said curvilinear path section (14) extends along, or approximates, an arc of a circle having a centre (40), wherein a horizontal line passing through said centre remains above the path section (14) and a vertical line passing through the centre remains in front of the path section (14).
The articulation system according to claim 3, wherein said arc of a circle has a radius greater than or equal to 50mm, preferably greater than or equal to 60mm, and/or less than or equal to 200mm, preferably less than or equal to 150mm.
The articulation system according to any one of the preceding claims, wherein said first hinge point (10) is located in a rear portion of said support for the seat (4).
The articulation system according to any one of the preceding claims, comprising at least one elastic element (20) operatively interposed between said main frame (2) and said support for the seat (4) and/or said support for the backrest (5), and wherein the articulation system (1) is configured to assume an at-rest configuration in the absence of tilting forces acting upon the support for the seat (4) and/or on the support for the backrest (5), and a maximum inclination configuration, wherein the support for the seat and the support for the backrest assume the maximum inclination possible with respect to the at-rest position.
The articulation system according to claim 6, wherein said guide (13) has a lower end, which has a lower abutment surface (21), and an upper end, which has an upper abutment surface (22), wherein in the at-rest configuration and in the maximum inclination configuration, the slider is found at the lower and upper end of the guide, respectively, abutting against said lower and upper abutment surface, respectively.
The articulation system according to claim 6 or 7, wherein, in said at-rest configuration, the first hinge point (10) is found, with reference to said reference plane, interposed between a line (30) vertical to said axis of rotation (9) and a line (31) vertical to the second hinge point (11).
The articulation system according to claim 6 or 7, wherein, in said at-rest configuration, the first hinge point (10) is found, with reference to said reference plane, on the opposite side of a line (30) vertical to said axis of rotation (9) with respect to the second hinge point (11).
The articulation system according to claim 8 or 9, wherein said first hinge point (10) is above a line (32) horizontal to said axis of rotation (9).
The articulation system according to any one of the preceding claims, wherein the support for the backrest (5) is solidly constrained to said articulation element (8).
The articulation system according to any one of claims from 1 to 10, wherein said support for the backrest (5) is connected to said articulation element (8) in an articulated manner, wherein the articulation system (1) comprises an additional articulation element that is rigid and hinged to said main frame (2) so that it can rotate about an additional axis of rotation, wherein said support for the backrest (5) is hinged to said articulation element (8) on a side of the articulation element that is opposite said first hinge point (10) of the seat with respect to said axis of rotation (9), and it is also hinged to said additional articulation element.
A chair comprising a supporting base for resting it on the ground, a rod (3) mounted on the supporting base for resting the chair on the ground, the articulation system (1) according to any one of the preceding claims, a seat (6) and a backrest (7), wherein said main frame (2) is rigidly mounted on said rod.