Mechanism for tilting the seat and / or the backrest of a chair

Abstract

A mechanism (10, 110, 210, 310) for tilting the seat (3) and / or backrest (2) of a chair, the mechanism (10, 110, 210, 310) comprising: - a frame (11, 111, 211, 311), adapted to be associated with a stem (12) of a gas-filled cylinder (13), - a backrest support (14, 114, 214, 314), coupled to said frame (11, 111, 211, 311), - a seat support (15, 115, 215, 315), coupled to said frame (11, 111, 211, 311) and to said backrest support (14, 114, 214, 314), - elastic return means (16, 116, 216, 316) for the elastic return of said backrest support (14, 114, 214, 314). The elastic return means (16, 116, 216, 316) are arranged between the frame (11, 111, 211, 311) and the backrest support (14, 114, 214, 314).

Description

[0001] The present invention relates to a mechanism for tilting the seat and / or the backrest of a chair.

[0002] The invention is applicable in the sector of furnishing, in particular, but not exclusively, in the area of office chairs.

[0003] Nowadays, in the sector of chairs, in particular office chairs, the need is felt to ensure the utmost comfort for the user.

[0004] For this reason, mechanisms are known that make it possible to adjust / vary the inclination of the backrest or of the seat, based on the needs of the user, or on the positions assumed by the user on the seat.

[0005] In recent years "weight-activated" mechanisms have become widespread on the market, which support the seat and the backrest of the chair and are associated in a downward region with the stem of a gas-filled spring.

[0006] Such mechanisms have a frame which is adapted to be associated with the gas-filled spring and is coupled to a seat support and to a backrest support.

[0007] Usually, the seat support is coupled at the front to the frame, and at the rear to the backrest support.

[0008] In the present description, the expressions "front", "rear", "in front", "at the rear", "below", "above", "in a downward region", "in an upward region" etc., refer to the configuration for use of the mechanism and of the chair as perceived by the user, who has the backrest and the backrest support behind him / her, the seat and the seat support in front of these, and, below the seat and the seat support, the frame.

[0009] Such weight-activated mechanisms make it possible to regulate the effort to move the backrest in proportion to the weight / stress of the user, via the minimal use of elastic return means.

[0010] Weight-activated mechanisms are known which comprise an elastic return element, often arranged in front and usually acting between the frame and the seat support, and also mechanisms that use traditional elastic elements which place limits on the shape and impose / define the volumes of the mechanism.

[0011] In this manner, when the user sits down, the mechanism allows tilting, with partial lifting of the seat and / or backward rotation of the backrest, in proportion to the weight of the user and to the position the user assumes on the chair.

[0012] The elastic element allows the backrest and / or the seat to return to the original position, while supporting the user and adapting to him / her, in order to ensure user comfort.

[0013] Such conventional techniques have some drawbacks, however.

[0014] In fact, in conventional mechanisms, the elastic element is constituted by leaf springs and / or helical springs which extend between the frame and the seat support and which determine a considerable complexity of construction and an unappealing visual impact.

[0015] Furthermore, in conventional mechanisms the elastic return element places constraints on the shape of the mechanism or of the frame.

[0016] If, for example, the elastic element is the frame itself, this results in a considerable stress on the elastic element, both when the user is resting against the backrest and when the user is seated, without placing their weight on the backrest.

[0017] In fact, when the user places their weight against the backrest, the backrest support, coupled to the frame and to the seat support, is moved upward and, via the seat support, places stress on the elastic return element, stressing it to bend upward in a manner that is uneven and non-repeatable from user to user.

[0018] However, even when the user is seated without leaning against the backrest, the elastic return element, which is arranged in front between the frame and the seat support, is stressed by the user's weight.

[0019] It follows from this that the elastic element is always under stress and this results in the need to make it of materials that are high-performing and costly, with the difficulty of sourcing the materials and the technical difficulty that derive from this, and with constraints on the shape that are imposed by its twofold function.

[0020] Moreover, in conventional mechanisms, with the elastic return element arranged in front, the positioning of the user on the chair, in addition to the user's weight, influence the response, and the response geometries, of the mechanism in terms of elastic return and of support of the backrest, in that the stress is transferred first from the seat support to the elastic element and to the frame, and then to the backrest support, also as a function of the shape and geometry of the frame.

[0021] This can determine an uneven response / return of the backrest, with discrepancies in the support of the user's back and potential problems to the user's spinal column.

[0022] US 5 499 861, EP 1 449 462 and US 6 250 715 disclose a mechanism for tilting the seat and / or backrest of a chair as defined in the preamble of claim 1.

[0023] The aim of the present invention is to provide a mechanism for tilting the seat and / or the backrest of a chair which is capable of avoiding the drawbacks of the known art in one or more of the above-mentioned aspects.

[0024] Within this aim, an object of the invention is to provide a mechanism for tilting the seat and / or the backrest of a chair that enables an elastic return of the backrest that is even and homogeneous, so avoiding causing problems to the spinal column of the user.

[0025] Another object of the invention is to provide a mechanism for tilting the seat and / or the backrest of a chair that makes it possible to provide the frame in widely varying shapes and materials, harmonizing it with the design of the chair, if desired.

[0026] A further object of the invention is to provide a mechanism for tilting the seat and / or the backrest of a chair that offers a pleasing visual impact and is simpler in construction with respect to conventional, similar mechanisms.

[0027] A still further object of the present invention is to overcome the drawbacks of the background art in a manner that is alternative to any existing solutions.

[0028] Another object of the invention is to provide a mechanism for tilting the seat and / or the backrest of a chair that is highly reliable, easy to implement, and at low cost.

[0029] This aim and these and other objects which will become better apparent hereinafter are achieved by a mechanism for tilting the seat and / or backrest of a chair, as defined in claim 1.

[0030] Further characteristics and advantages of the invention will become more apparent from the description of some preferred, but not exclusive, embodiments of the mechanism for tilting the seat and / or the backrest of a chair, according to the invention, which are illustrated for the purposes of non-limiting example in the accompanying drawings wherein: Figure 1 is an overall perspective view of a mechanism for tilting the seat and / or the backrest of a chair according to the invention, in a first embodiment; Figures 2a and 2b are two different exploded views of the mechanism of Figure 1; Figures 3a and 3b show a cross-sectional view of the mechanism of Figure 1 in a respective configuration for use; Figures 4a and 4b show a cross-sectional view of a second embodiment of a mechanism for tilting the seat and / or the backrest of a chair according to the invention, in a respective configuration for use; Figure 5 is an overall perspective view of a mechanism for tilting the seat and / or the backrest of a chair according to the invention, in a third embodiment; Figures 6a and 6b are two different exploded views of the mechanism of Figure 5; Figures 7a and 7b show a cross-sectional view of the mechanism of Figure 5 in a respective configuration for use; Figure 8 is an overall perspective view of a mechanism for tilting the seat and / or the backrest of a chair according to the invention, in a fourth embodiment; Figures 9a and 9b are two different exploded views of the mechanism of Figure 8; Figures 10a and 10b show a cross-sectional view of the mechanism of Figure 8 in a respective configuration for use.

[0031] With reference to Figures 1 to 3b, a mechanism for tilting the seat and / or the backrest of a chair, according to the invention, in a first embodiment, is generally designated by the reference numeral 10.

[0032] The mechanism 10 is used in a chair 1, partially visible in Figures 3a and 3b, which comprises a backrest 2 and a seat 3.

[0033] The mechanism 10 according to the invention is defined in claim 1 and comprises amongst others: a frame 11, adapted to be associated with a stem 12 of a gas-filled cylinder 13, or other floor support, a backrest support 14, coupled at the rear of the frame 11, a seat support 15, coupled to the frame 11, above this, and to the backrest support 14, elastic return means 16 for the elastic return of the backrest support 14.

[0034] One of the peculiarities of the invention consists in that the means of elastic return are arranged between the frame and the backrest support.

[0035] In the first embodiment, illustrated in Figures 1 to 3b, the elastic return means 16 are constituted by a clip 39.

[0036] The backrest support 14 is hinged: to the frame 11, along a first axis P1, which is fixed, to the seat support 15, along a second axis P2, which is movable and parallel to the first axis P1 and arranged above it.

[0037] In the present description, the expression "fixed axis" means that the axis cannot translate when the mechanism is being used.

[0038] In the present description, the expression "movable axis" means that the axis can translate when the mechanism is being used.

[0039] The frame 11 comprises: a body 17, which is at least partially arc-like and in turn has a first hole 19, which is a through hole, for the insertion of the stem 12 of the gas-filled cylinder 13, a first tab 18, at a first longitudinal end of the body 17, such first tab 18 defining a bracket directed toward the backrest support 14, a second tab 20, which is inclined toward the backrest support 14 and is provided with a first slot 21, at a second longitudinal end of the body 17, opposite to its first longitudinal end.

[0040] In other embodiments, not shown in the figures, the body 17 does not need to be arc-like, and it can have a different shape and two or more arms, with a like number of second tabs and corresponding slots.

[0041] Between the first tab 18 and the body 17 a first opening 22 is provided, which is a through opening, for the at least partial insertion of the elastic return means 16.

[0042] The body 17 is associated with a rod 23, which is at least partially arranged at the first hole 19, for actuating the gas-filled cylinder 13.

[0043] The first tab 18 has: a first portion 24, substantially flat, which has a step 28 on the face directed toward the backrest support 14, a second through hole 25, which has an axis of extension that is parallel to the plane of arrangement of the portion 24 and coincides with the first axis P1, two mirror-symmetrical protrusions 26a, 26b of the first portion 24, proximate to / at the second hole 25, each having a recess 27a, 27b.

[0044] The backrest support 14 has: a second portion 29, which is substantially flat, for association with the backrest 2, a third portion 30, which is inclined with respect to the second portion 29 and is directed toward the first portion 24, above the step 28, a second opening 31, which is a through opening, between the second portion 29 and the third portion 30, for the at least partial insertion of the elastic return means 16, two opposite and mirror-symmetrical substantially T-shaped portions 32a, 32b, respectively a substantially T-shaped first portion 32a and a substantially T-shaped second portion 32b.

[0045] Each one of the substantially T-shaped portions 32a, 32b: lies on a plane perpendicular to the plane of arrangement of the second portion 29 and to the plane of arrangement of the third portion 30, has the core 33a, 33b of the T at the second portion 29, and in a single body with it, and the wing 34a, 34b of the T at the third portion 30, and in a single body with it.

[0046] Such wing 34a, 34b has: at / proximate to a first end thereof: a third hole 35a, 35b, which is a through hole, corresponding to the second hole 25, a raised portion, corresponding to the recess 27a, 27b, and which is only visible in Figure 2b (indicated by the reference numeral 36a), at / proximate to a second end thereof, opposite to the previous end: a fourth hole 37a, 37b.

[0047] In particular, the recess 27a, 27b has a larger dimension than the corresponding raised portion 36a, and permits a partial movement thereof, as a consequence of the rotation of the backrest support 14.

[0048] The raised portion 36a, inserted in the recess 27a, 27b, is adapted to guide the movement of the backrest support, when this is in rotation, between two predefined end positions, which allow a maximum rotation of the backrest support 14 in the order of 15°.

[0049] The mechanism 10 comprises a first pivot 38, which passes through: the third hole 35a of the substantially T-shaped first portion 32a, the second hole 25, the third hole 35b of the substantially T-shaped second portion 32b, and has an axis of extension that coincides with the first axis P1.

[0050] The first tab 18 is interposed between the substantially T-shaped first portion 32a and the substantially T-shaped second portion 32b.

[0051] The clip 39 has a substantially U-shaped profile with a first wing 40a and a second wing 40b, and is arranged so as to enclose and clamp together the first portion 24 and the third portion 30.

[0052] Advantageously, the first wing 40a of the clip 39 is inserted in the first opening 22, while the second wing 40b of the clip 39 is inserted in the second opening 31.

[0053] The first wing 40a has an end tooth 41a which is coupled by snap action to a corresponding locator 42a on the third portion 30.

[0054] The second wing 40b has an end tooth 41b, mirror-symmetrical to the tooth 41a of the first wing 40a, which is coupled by snap action to a corresponding locator 42b of the first portion 24.

[0055] Another peculiarity of the invention consists in that the elastic return means 16 are completely internal to the bulk of the backrest support 14 and / or of the frame 11, when the mechanism is in the inactive position, illustrated in Figures 1 and 3a.

[0056] The expression "completely internal to the bulk" in the present description means that the mechanism is hidden from view at least when it is looked at from the side, in a direction parallel to the first axis P1.

[0057] In particular, the clip 39 is completely internal to the bulk of the backrest support 14 in the inactive position of the mechanism 10.

[0058] The seat support 15 has a flat body 43, with a quadrangular profile, adapted to be fixed to the seat 3 of the chair 1.

[0059] The flat body 43 has: a third tab 44, which is hollow and directed toward the frame 11, and is provided with a fifth hole 45, which is a through hole and has an axis of extension that coincides with the second axis P2, two opposite and mirror-symmetrical fourth tabs 46a, 46b, which are directed toward the frame 11, respectively a first fourth tab 46a and a second fourth tab 46b, each one provided with a sixth hole 47a, 47b, which is a through hole.

[0060] In particular the fifth hole 45 corresponds to the fourth hole 37a of the substantially T-shaped first portion 32a and to the fourth hole 37b of the substantially T-shaped second portion 32b.

[0061] The mechanism 10 comprises a second pivot 48, which passes through: the fourth hole 37a of the substantially T-shaped first portion 32a, the fifth hole 45, the fourth hole 37b of the substantially T-shaped second portion 32b, and has an axis of extension that coincides with the second axis P2.

[0062] The third tab 44 is interposed between the substantially T-shaped first portion 32a and the substantially T-shaped second portion 32b.

[0063] The second tab 20 is interposed between the first fourth tab 46a and the second fourth tab 46b.

[0064] Advantageously, the sixth hole 47a of the first fourth tab 46a and the sixth hole 47b of the second fourth tab 46b are arranged at the first slot 21 of the second tab 20.

[0065] The mechanism 10 comprises a third pivot 49, which passes through: the sixth hole 47a of the first fourth tab 46a, the first slot 21, the sixth hole 47b of the second fourth tab 46b, and has an axis of extension that is parallel to the first axis P1 and to the second axis P2.

[0066] Another peculiarity of the invention consists in that the axis of rotation of the elastic return means 16 coincides with the fixed axis of rotation of the backrest support, i.e. the first axis P1.

[0067] With reference to Figures 3a and 3b, the use of the mechanism 10 according to the invention is the following.

[0068] Figure 3a shows an inactive configuration of the mechanism 10 and / or in the absence of stress on the backrest 2 of the chair 1.

[0069] When the backrest 2 is pushed, in the direction indicated by the arrow R in Figure 3b, the backrest support 14 rotates about the first axis P1, pulling the first wing 40a of the clip 39 and moving the third portion 30 away from the first portion 24.

[0070] At the same time, the backrest support 14 also pulls the seat support 15, which rises up in a front region as a result of the third pivot 49 sliding along the first slot 21 of the second tab 20.

[0071] When the stress is removed from the backrest, by virtue of the elastic return of the clip 39, the first wing 40a is returned to the starting / inactive configuration (shown in Figure 3a) and, at the same time, the backrest support 14 and the seat support 15 return to the inactive configuration.

[0072] Figures 4a and 4b show a second embodiment of a mechanism according to the invention, generally designated by the reference numeral 110.

[0073] In these figures, the elements corresponding to the elements of the first embodiment described above are indicated by the same number increased by 100.

[0074] The mechanism 110 comprises means 150 for adjusting the elastic return tension, which interact with the elastic return means 116.

[0075] Such means 150 for adjusting the elastic return tension comprise an element with a substantially F-shaped profile that has: a core 151 provided with a hand grip 152, a first wing 153, which extends at right angles from the core 151 and is at least partially inserted in a corresponding seat 154 of the body 117 of the frame 111, said seat being directed toward the clip 139 and below the latter, a second wing 155, which is parallel to the first wing 153 and extends below the body 117 of the frame 111.

[0076] Advantageously, the body 117 has a protruding part 156 which is interposed between such first wing 153 of the element with a substantially F-shaped profile and such second wing 155 of the element with a substantially F-shaped profile.

[0077] Advantageously the first wing 153 of the element with a substantially F-shaped profile is in contact and interacts with the clip 139 substantially in the central portion 157 of the latter, interposed between its wings 140a and 140b.

[0078] To adjust / modify the elastic return tension of the clip 139, it is sufficient to actuate the means 150, shifting the first wing 153 of the element with a substantially F-shaped profile in the direction of the arrow V of Figure 4b.

[0079] In this manner the contact between the first wing 153 and the central portion 157 is modified / shifted, as a consequence varying the elastic return tension and adapting it to the needs of the user.

[0080] Figures 5 to 7b show a third embodiment of a mechanism according to the invention, designated by the reference numeral 210.

[0081] The mechanism 210 comprises: a frame 211, adapted to be associated with a stem of a gas-filled cylinder, a backrest support 214, coupled at the rear of the frame 211, a seat support 215, coupled to the frame 211, above this, and to the backrest support 214, means 216 for the elastic return of the backrest support 214.

[0082] The backrest support 214 is hinged: to the frame 211, along a first axis P1', which is fixed, to the seat support 215, along a second axis P2', which is movable and parallel to the first axis P1' and arranged above it.

[0083] The frame 211 comprises: a body 217, which is at least partially arc-like and in turn has a first hole 219, which is a through hole, for the insertion of the stem of the gas-filled cylinder, two mirror-symmetrical fifth tabs 218a and 218b, at a first longitudinal end of the body 217, such fifth tabs 218a, 218b defining a bracket directed toward the backrest support 214, two mirror-symmetrical sixth tabs 220a and 220b, which are inclined toward the backrest support 214 and are each provided with a seventh hole 221a, 221b, at a second longitudinal end of the body 217, opposite to its first longitudinal end.

[0084] In other embodiments, not shown in the figures, the body 217 does not need to be arc-like, and it can have a different shape and two or more arms, with a like number of sixth tabs and corresponding holes.

[0085] The fifth tabs 218a, 218b extend above a base 270, which is substantially flat and coplanar with the body 217 and is passed through by a second hole 225, which is a through hole and has an axis of extension that coincides with the first axis P1'.

[0086] The backrest support 214 has: a second portion 229, which is substantially flat, for association with the backrest, a third portion 230, which is inclined with respect to the previous portion and is facing the fifth tabs 218a, 218b, a second opening 231, which is a through opening, between the second portion 229 and the third portion 230, for the at least partial insertion of the elastic return means 216, two opposite and mirror-symmetrical substantially T-shaped portions 232a, 232b, respectively a substantially T-shaped first portion 232a and a substantially T-shaped second portion 232b.

[0087] Each one of the substantially T-shaped portions 232a, 232b: lies on a plane perpendicular to the plane of arrangement of the second portion 229 and to the plane of arrangement of the third portion 230, has the core 233a, 233b of the T at the second portion 229, and in a single body with it, and the wing 234a, 234b of the T at the third portion 230, and in a single body with it.

[0088] Such wing 234a, 234b has, at / proximate to a first end thereof, a third hole 235a, 235b, which is a through hole and corresponds to the second hole 225.

[0089] The backrest support 214 has a fourth hole 237, which is a through hole and has an axis of extension that is substantially parallel to the plane of arrangement of the frame 211 and coincides with the second axis P2', arranged proximate to the upper end of the third portion 230.

[0090] The mechanism 210 comprises a first pivot 238, which passes through: the third hole 235a of the substantially T-shaped first portion 232a, the second hole 225, the third hole 235b of the substantially T-shaped second portion 232b, and has an axis of extension that coincides with the first axis P1'.

[0091] The fifth tabs 218a, 218b are interposed between the substantially T-shaped first portion 232a and the substantially T-shaped second portion 232b.

[0092] In such embodiment the elastic return means 216 comprise a leaf spring 260, separate from the frame 211.

[0093] In particular, the leaf spring 260 has a substantially V-shaped profile with: a first part 261, which is fixed to the frame 211, a second part 262, which is substantially oblique with respect to the previous part, is inserted in the second opening 231 and faces the third portion 230 of the backrest support 214, and substantially traces the profile of the fifth tabs 218a, 218b.

[0094] Advantageously, the first part 261 has a C-shaped profile with a recess 263, which partially surrounds the first hole 219, and two wings 264a, 264b.

[0095] The first part 261 is inserted, at least partially, into a corresponding seat 265 of the frame 211, arranged below the first tabs 218a, 218b, at the base 270, and fixed to it by means of respective screws 266 arranged at the wings 264a, 264b.

[0096] The seat support 215 has a flat body 243, with a quadrangular profile, adapted to be fixed to the seat of the chair.

[0097] In this embodiment, the seat support 215 has a seventh tab 267, which has a second slot 268 interposed between the sixth tabs 220a, 220b of the frame 211 and is coupled to it by means of the third pivot 249.

[0098] The third pivot 249 passes through, in the following order: the seventh hole 221a of the second tab 220a, the slot 268, the other seventh hole 221b in the other second tab 220b.

[0099] The seat support 215 has two mirror-symmetrical eighth holes 269a, 269b, which are through holes and which each correspond to the fourth hole 237 of the backrest support 214, with an axis of extension that coincides with the second axis P2'.

[0100] The seat support 215 is coupled to the backrest support 214 by means of a second pivot 248, which passes through: a first eighth hole 269a, the fourth hole 237, a second eighth hole 269b, and has an axis of extension that coincides with the second axis P2'.

[0101] With reference to Figures 7a and 7b, the use of the mechanism 210 according to the invention is the following.

[0102] Figure 7a shows an inactive configuration of the mechanism 210 and / or in the absence of stress on the backrest of the chair.

[0103] When the backrest is pushed, in the direction indicated by the arrow R1 in Figure 7b, the backrest support 214 rotates about the first axis P1', pulling the second part 262 of the leaf spring 260 and moving the third portion 230 away from the fifth tabs 218a, 218b.

[0104] At the same time, the backrest support 214 also pulls the seat support 215, which rises up in a front region as a result of the third pivot 249 sliding along the slot 268 of the fifth tab 267.

[0105] When the stress is removed from the backrest, by virtue of the elastic return of the leaf spring 260, the second part 262 is returned to the starting / inactive configuration (shown in Figure 7a) and, at the same time, the backrest support 214 and the seat support 215 return to the inactive configuration.

[0106] In other embodiments, not shown in the figures, the mechanism 210 comprises means for adjusting the elastic return tension of the means 216.

[0107] Figures 8 to 10b show a fourth embodiment of a mechanism according to the invention, designated by the reference numeral 310.

[0108] In these figures, the elements corresponding to the elements of the third embodiment, described above and illustrated in Figures 5 to 7b, are indicated by the same number increased by 100.

[0109] In particular, in the fourth embodiment, differently from the previous embodiment, the leaf spring 360 is in a single body with the frame 311.

[0110] The mechanism 310 comprises: a frame 311, adapted to be associated with a stem of a gas-filled cylinder, a backrest support 314, coupled at the rear of the frame 311, a seat support 315, coupled to the frame 311, above this, and to the backrest support 314, means 316 for the elastic return of the backrest support 314.

[0111] The backrest support 314 is hinged: to the frame 311, along a first axis P1", which is fixed, to the seat support 315, along a second axis P2", which is movable and parallel to the first axis P1" and arranged above it.

[0112] The frame 311 comprises: a body 317, which is at least partially arc-like and in turn has a first hole 319, which is a through hole, for the insertion of the stem of the gas-filled cylinder, two mirror-symmetrical fifth tabs 318a and 318b, at a first longitudinal end of the body 317, such fifth tabs 318a, 318b defining a bracket directed toward the backrest support 314, two mirror-symmetrical sixth tabs 320a and 320b, which are inclined toward the backrest support 314 and are each provided with a third slot 371a, 371b, at a second longitudinal end of the body 317, opposite to its first longitudinal end.

[0113] In other embodiments, not shown in the figures, the body 317 does not need to be arc-like, and it can have a different shape and two or more arms, with a like number of sixth tabs and corresponding slots.

[0114] The fifth tabs 318a, 318b extend above a base 370, which is substantially flat and coplanar with the body 317 and is passed through by a second hole 325, which is a through hole and has an axis of extension that coincides with the first axis P1".

[0115] The backrest support 314 has: a second portion 329, which is substantially flat, for association with the backrest, a third portion 330, which is inclined with respect to the previous portion and is facing the fifth tabs 318a, 318b, a second opening, which is a through opening, between the second portion 329 and the third portion 330, for the at least partial insertion of the elastic return means 316, two opposite and mirror-symmetrical substantially T-shaped portions 332a, 332b, respectively a substantially T-shaped first portion 332a and a substantially T-shaped second portion 332b.

[0116] Each one of the substantially T-shaped portions 332a, 332b: lies on a plane perpendicular to the plane of arrangement of the second portion 329 and to the plane of arrangement of the third portion 330, has the core 333a, 333b of the T at the second portion 329, and in a single body with it, and the wing 334a, 334b of the T at the third portion 330, and in a single body with it.

[0117] Such wing 334a, 334b has, at / proximate to a first end thereof, a third hole 335a, 335b, which is a through hole and corresponds to the second hole 325.

[0118] The backrest support 314 has a fourth hole 337, which is a through hole and has an axis of extension that is substantially parallel to the plane of arrangement of the frame 311 and coincides with the second axis P2", arranged proximate to the upper end of the third portion 330.

[0119] The mechanism 310 comprises a first pivot 338, which passes through: the third hole 335a of the substantially T-shaped first portion 332a, the second hole 325, the third hole 335b of the substantially T-shaped second portion 332b, and has an axis of extension that coincides with the first axis P1".

[0120] The fifth tabs 318a, 318b are interposed between the substantially T-shaped first portion 332a and the substantially T-shaped second portion 332b.

[0121] In particular, the leaf spring 360 has a substantially V-shaped profile with: a first part 361, which is fixed to the frame 311 and is in a single body with it, at the base 370, a second part 362, which is substantially oblique with respect to the previous part, is inserted in the second opening 331 and faces the third portion 330 of the backrest support 314, and substantially traces the profile of the fifth tabs 318a, 318b.

[0122] The seat support 315 has a flat body 343, with a quadrangular profile, adapted to be fixed to the seat of the chair.

[0123] In this embodiment, the seat support 315 has a seventh tab 367, which is interposed between the sixth tabs 320a, 320b and is provided with two opposite and mirror-symmetrical fourth pivots 349a, 349b, each one inserted into a corresponding third slot 371a, 371b.

[0124] The fourth pivots 349a, 349b extend toward the transverse sides of the mechanism 310, and along an axis that is parallel to the first axis P1" and to the second axis P2".

[0125] The seat support 315 has two mirror-symmetrical eighth holes 369a, 369b, which are through holes and which each correspond to the fourth hole 337 of the backrest support 314, with an axis of extension that coincides with the second axis P2".

[0126] The seat support 315 is coupled to the backrest support 314 by means of a second pivot 348, which passes through: a first eighth hole 369a, the fourth hole 337, a second eighth hole 369b, and has an axis of extension that coincides with the second axis P2".

[0127] With reference to Figures 10a and 10b, the use of the mechanism 310 according to the invention is the following.

[0128] Figure 10a shows an inactive configuration of the mechanism 310 and / or in the absence of stress on the backrest of the chair.

[0129] When the backrest is pushed, in the direction indicated by the arrow R2 in Figure 10b, the backrest support 314 rotates about the first axis P1", pulling the second part 362 of the leaf spring 360 and moving the third portion 330 away from the fifth tabs 318a, 318b.

[0130] At the same time, the backrest support 314 also pulls the seat support 315, which rises up in a front region by virtue of the fourth pivots 349a, 349b sliding along the third slots 371a, 371b of the sixth tabs 320a, 320b.

[0131] When the stress is removed from the backrest, by virtue of the elastic return of the leaf spring 360, the second part 362 is returned to the starting / inactive configuration (shown in Figure 10a) and, at the same time, the backrest support 314 and the seat support 315 return to the inactive configuration.

[0132] In other embodiments, not shown in the figures, the mechanism 310 comprises means for adjusting the elastic return tension of the means 316.

[0133] It should be noted that with a mechanism 10, 110, 210, 310 according to the invention, the axis of rotation of the elastic return means 16, 116, 216, 316 coincides with the fixed axis of rotation of the backrest support, i.e. the first axis P1, P1', P1".

[0134] It should be noted that in the mechanism according to the invention, since the means of elastic return of the backrest support are arranged at the rear and are interposed between the backrest support and the frame, the response to the stressing of the mechanism is independent of the weight of the user and / or of their posture and distribution of their body on the chair, but rather it depends only on the stress imparted to the backrest.

[0135] This also results in even support over the entire surface of the backrest, so avoiding causing problems to the spinal column of the user.

[0136] Furthermore, in a mechanism 10, 110, 210, 310 according to the invention the elastic return means 16, 116, 216, 316 are completely internal to the bulk of the backrest support 14, 114, 214, 314 and / or of the frame 11, 111, 211, 311, when the mechanism is in the inactive position, and this results in a pleasing visual impact of the mechanism.

[0137] In practice it has been found that the invention fully achieves the intended aim and objects by providing a mechanism for tilting the seat and / or the backrest of a chair that enables an elastic return of the backrest that is even and homogeneous, so avoiding causing problems to the spinal column of the user.

[0138] Furthermore, with the invention a mechanism has been devised for tilting the seat and / or the backrest of a chair that enables an elastic return of the backrest independently of the weight of the user.

[0139] Moreover, with the invention a mechanism for tilting the seat and / or the backrest of a chair has been provided that offers a pleasing visual impact and is simpler in construction with respect to conventional, similar mechanisms.

[0140] The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other, technically equivalent elements.

[0141] In practice the materials employed, provided they are compatible with the specific use, and the contingent dimensions and shapes, may be any according to requirements and to the state of the art.

[0142] The disclosures in Italian Patent Application No. 102024000001044 from which this application claims priority are incorporated herein by reference.

[0143] Where technical features mentioned in any claim are followed by reference signs, such reference signs have been inserted for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.

Claims

1. A mechanism (10, 110, 210, 310) for tilting the seat (3) and / or backrest (2) of a chair, said mechanism (10, 110, 210, 310) comprising: - a frame (11, 111, 211, 311), adapted to be associated with a stem (12) of a gas-filled cylinder (13), - a backrest support (14, 114, 214, 314), coupled to said frame (11, 111, 211, 311), - a seat support (15, 115, 215, 315), coupled to said frame (11, 111, 211, 311) and to said backrest support (14, 114, 214, 314), - elastic return means (16, 116, 216, 316) for the elastic return of said backrest support (14, 114, 214, 314), said elastic return means (16, 116, 216, 316) being arranged between said frame (11, 111, 211, 311) and said backrest support (14, 114, 214, 314), characterized in that said backrest support (14, 114, 214, 314) has: - a second portion (29, 129, 229, 329), which is substantially flat, for association with said backrest (2), - a third portion (30, 130, 230, 330), which is inclined with respect to the previous portion, - a second opening (31, 131, 231, 331), which is a through opening, between said second portion (29, 129, 229, 329) and said third portion (30, 130, 230, 330), in which said elastic return means (16, 116, 216, 316) are at least partially inserted.

2. The mechanism (10, 110, 210, 310) according to claim 1, characterized in that said elastic return means (16, 116, 216, 316) are arranged within the footprint of said backrest support (14, 114, 214, 314) and / or the footprint of said frame (11, 111, 211, 311) when the mechanism (10, 110, 210, 310) is in the inactive position.

3. The mechanism (10, 110, 210, 310) according to one or more of the preceding claims, characterized in that said backrest support (14, 114, 214, 314) is hinged: - to said frame (11, 111, 211, 311) along a first axis (P1, P1', P1"), which is fixed, - to the seat support (15, 115, 215, 315) along a second axis (P2, P2', P2"), which is movable and parallel to said first axis (P1, P1', P1") and arranged above it, and the axis of rotation of said elastic return means (16, 116, 216, 316) coincides with said first axis (P1, P1', P1").

4. The mechanism (10, 110) according to one or more of the preceding claims, characterized in that said elastic return means (16, 116) are constituted by a clip (39, 139).

5. The mechanism (10, 110) according to one or more of the preceding claims, characterized in that said frame (11) comprises: - a body (17, 117), which in turn has a first hole (19, 119), which is a through hole, for the insertion of the stem (12) of the gas-filled cylinder (13), - at least one first tab (18, 118), at a first longitudinal end of said body (17, 117), said at least one first tab (18, 118) defining a bracket directed toward said backrest support (14, 114), between said at least one first tab (18, 118) and said body (17, 117) there being a first opening (22, 122), which is a through opening, for the at least partial insertion of said elastic return means (16, 116), - at least one second tab (20, 120), which is inclined toward said backrest support (14, 114) and is arranged at a second longitudinal end of said body (17, 117), which is opposite to its first longitudinal end, said at least one second tab (20, 120) being connected to said seat support (15, 115).

6. The mechanism (10) according to one or more of the preceding claims, characterized in that said at least one first tab (18) has: - a first portion (24), which is substantially flat, - a second hole (25), which is a through hole and has an axis of extension that is parallel to the plane of arrangement of said first portion (24) and coincides with said first axis (P1), - two mirror-symmetrical protrusions (26a, 26b) of said first portion (24), proximate to / at said second hole (25), each one of said protrusions (26a, 26b) having a recess (27a, 27b).

7. The mechanism (10) according to one or more of the preceding claims, characterized in that said wing (34a, 34b) of said T-shape has: - at / proximate to a first end thereof: - a third hole (35a, 35b), which is a through hole and corresponds to said second hole (25), said third hole (35a, 35b) and said second hole (25) being passed through by a first pivot (38), - a raised portion (36a) which corresponds to said recess (27a, 27b) and is inserted into it, said recess (27a, 27b) being larger than the corresponding raised portion (36a), - at / proximate to a second end thereof, which is opposite to the previous end: a fourth hole (37a, 37b) in which a second pivot (48, 148) is inserted for connection to said seat support (15).

8. The mechanism (10, 110) according to one or more of the preceding claims, characterized in that said clip (39, 139) has a substantially U-shaped profile, with a first wing (40a, 140a) and a second wing (40b, 140b), and is arranged so as to enclose and clamp together said first portion (24) and said third portion (30, 130), said first wing (40a, 140a) of said clip (39, 139) being inserted in said first opening (22, 122), said second wing (40b, 140b) of said clip (39, 139) being inserted in said second opening (31, 131).

9. The mechanism (210, 310) according to one or more of claims 1 to 4, characterized in that said elastic return means (216, 316) comprise a leaf spring (260, 360).

10. The mechanism (210, 310), according to the preceding claim, characterized in that said frame (211, 311) comprises: - a body (217, 317), which is at least partially arc-like and in turn has a first hole (219, 319), which is a through hole, for the insertion of said stem of said gas-filled cylinder, - at least one fifth tab (218a, 218b, 318a, 318b) at a first longitudinal end of the body (217, 317), said at least one fifth tab (218a, 218b, 318a, 318b) defining a bracket directed toward said backrest support (214, 314), said at least one fifth tab (218a, 218b, 318a, 318b) extending above a base (270, 370) which is substantially flat and coplanar with respect to said body (217, 317), said base (270, 370) being passed through by a second through hole (225, 325), which has an axis of extension that coincides with said first axis (P1', P1"), - at least one sixth tab (220a, 220b, 320a, 320b), which is inclined toward said backrest support (214, 314) and is coupled to said seat support (215, 315) at a second longitudinal end of said body (217, 317) which is opposite to said first longitudinal end.

11. The mechanism (210, 310) according to claim 9 or 10, characterized in that said wing (234a, 234b, 334a, 334b) of said T-shape has, at / proximate to a first end thereof, a third hole (235a, 235b, 335a, 335b), which is a through hole and corresponds to said second hole (225, 325), said third hole (235a, 235b, 335a, 335b) and said second hole (225, 325) being passed through by a first pivot (238, 338).

12. The mechanism (210, 310) according to one or more of claims 9 to 11, characterized in that said backrest support (214, 314) has a fourth hole (237, 337), which is a through hole, with an axis of extension that is substantially parallel to the plane of arrangement of said frame (211, 311) and coincides with said second axis (P2', P2"), said fourth hole (237, 337) being arranged proximate to the upper end of said third portion (230, 330), said seat support (215, 315) being coupled to said backrest support (214, 314) by means of a second pivot (248, 348) that passes through said fourth hole (237, 337).

13. The mechanism (210, 310) according to one or more of claims 9 to 12, characterized in that said leaf spring (260, 360) has a substantially V-shaped profile with: - a first part (261, 361), which is fixed to said frame (211, 311), - a second part (262, 362), which is substantially oblique with respect to the previous part, is inserted in said second opening (231, 331) and faces said third portion (230, 330) of said backrest support (214, 314), said second part (262, 362) substantially tracing the profile of said at least one fifth tab (218a, 218b, 318a, 318b).

14. The mechanism (110, 210, 310) according to one or more of claims 1 to 8 or 9 to 13, characterized in that it comprises means (150) for adjusting the elastic return tension.

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