EP0059141A1 - Wheel chair with means for aiding a patient to stand up - Google Patents

Abstract

The invention relates to a wheelchair allowing the recovery of its user, comprising a frame 1 which rests on the ground by means of displacement members 4 and 7 and supports a seat 3. This wheelchair comprises a mobile structure with two frames 14 which extend parallel to the sides of the chair, a frame on each side of this chair, and which are pivotally mounted on the frame around transverse horizontal axes 19 which by allowing a tilting forward of substantially 90 ° during from which is moved a set of bars 30-31-32-33 which are arranged, initially, in the first position of the structure, behind (2) of the seat 3, and which in the second position of this structure, are arranged in the space in front (T) of seat 3. One application is the creation of armchairs for paraplegics.

Description

Wheelchairs are already known, in particular used by paraplegics, which allow the user to straighten in a vertical position.

It is indeed recognized today that it is necessary, for multiple reasons - physiological, psychological, in particular - to allow a handicapped person to stand upright during the day. This operation, called by many specialists "verticalization", was essentially carried out by providing fixed installations providing the disabled with the verticalization facilities. Some wheelchairs have their movable seat and back, also allowing recovery.

The invention proposes a new arrangement equipping a wheelchair, allowing the verticalization of the disabled.

The subject of the invention is therefore a wheelchair allowing the recovery of its user, in particular for use by a paraplegic, comprising a frame resting on the ground by means of front and rear displacement members and supporting a seat, and a structure mobile separate from the seat and capable of occupying the following two positions, a first position, in which this structure is retracted so as, on the one hand, to leave at least the space located in front of the seat clear, on the other hand , to maintain the possibilities of rolling the chair, and, a second position, in which this structure, on the one hand, is placed in said space located in front of the seat while being accessible to the hands of a user seated in the armchair, on the other hand, is supported on the part of the ground located in front of said seat.

The structure comprises two frames which extend substantially parallel to the sides of the chair, one frame on each side of this chair, and which are pivotally mounted on the frame around transverse horizontal axes which allow it to tilt forward substantially 90 ° during which is moved a set of bars which are arranged, initially, in the first position of the structure, behind the seat, and which, in the second position of this structure, are arranged in the space located in front of said seat.

• - dans sa première position, la structure a un encombrement latéral, de chaque côté du siège et dans l'espace situé au-dessus du siège, qui est sensiblement celui du bâti usuel d'un fauteuil roulant ;
• - le fauteuil comprend un repose-pieds, qui est monté sur le bâti, mobile par rapport à ce bâti, et susceptible d'occuper deux positions, l'une, correspondant aux possibilités de roulage du fauteuil, dans laquelle il est situé au-dessus du sol, sans y être au contact, l'autre position, correspondant à ladite deuxième position de la structure, dans laquelle il est en appui ferme sur le sol et soulève les organes de déplacement avant du fauteuil, cependant que les deuxdits cadres, dans cette deuxième position de la structure, sont en appui sur ledit repose-pieds ;
• - un dispositif de verrouillage permet le blocage du repose-pieds, dans sa position d'appui sur le sol ;
• - un autre dispositif de verrouillage réalise, dans ladite deuxième position de la structure, la solidarisation de chacun des deux cadres sur le repose-pieds ;
• - la structure comprend un dispositif d'appui des genoux, qui est au moins partiellement amovible, et qui, dans la deuxième position de la structure, s'étend horizontalement transversalement, à la hauteur des genoux d'un utilisateur du fauteuil ;
• - la structure comporte un élément mobile qui, dans la deuxième position de cette structure, est susceptible d'être placé horizontalement transversalement, sensiblement à proximité du plan vertical passant par le bord avant du siège, en étant disposé à une hauteur au moins égale à celle du bassin d'un utilisateur placé debout sur le repose-pieds dudit fauteuil, et qui est distinct du siège du fauteuil, ledit siège ayant une position fixe par rapport au bâti dans les première et deuxième positions de la structure ;
• - dans la deuxième position de la structure, les deux cadres sont reliés par un élément rigide démontable, qui, dans cette deuxième position, est disposé horizontalement et transversalement et assure la rigidification de cette structure ;
• - ledit élément rigide, dans la deuxième position de la structure, s'étend sensiblement à la hauteur du tronc d'un utilisateur assis dans le fauteuil ;
• - chaque cadre est maintenu pivotant autour de son axe par un dispositif à montage et démontage rapides.

In addition, the following advantageous arrangements are preferably adopted:

• - In its first position, the structure has a lateral bulk, on each side of the seat and in the space above the seat, which is substantially that of the usual frame of a wheelchair;
• - The chair includes a footrest, which is mounted on the frame, movable relative to this frame, and capable of occupying two positions, one, corresponding to the possibilities of rolling the chair, in which it is located above the ground, without being in contact with it, the other position, corresponding to said second position of the structure, in which it is in firm support on the ground and lifts the front displacement members of the chair, while the two said frames, in this second position of the structure, are supported on said footrest;
• - A locking device allows the blocking of the footrest, in its support position on the ground;
• - Another locking device performs, in said second position of the structure, the joining of each of the two frames on the footrest;
• - The structure comprises a knee support device, which is at least partially removable, and which, in the second position of the structure, extends horizontally transversely, at the height of the knees of a user of the chair;
• - The structure comprises a movable element which, in the second position of this structure, is capable of being placed horizontally transversely, substantially near the vertical plane passing through the front edge of the seat, being arranged at a height at least equal to that of the pelvis of a user placed standing on the footrest of said chair, and who is distinct from the seat of the chair, said seat having a fixed position relative to the frame in the first and second positions of the structure;
• - In the second position of the structure, the two frames are connected by a removable rigid element, which, in this second position, is arranged horizontally and transversely and ensures the stiffening of this structure;
• - Said rigid element, in the second position of the structure, extends substantially at the height of the trunk of a user seated in the chair;
• - each frame is kept pivoting about its axis by a device for rapid assembly and disassembly.

The invention will be better understood, and secondary characteristics and their advantages will appear during the description of an embodiment given below by way of example.

It is understood that the description and the drawings are given for information only and are not limiting.

• - la figure 1 est une vue en élévation d'un fauteuil conforme à l'invention, dans une première configuration ;
• - la figure 2 est une vue en élévation d'un détail agrandi du fauteuil de la figure 1, dans une deuxième configuration ;
• - la figure 3 est une vue perspective du fauteuil des figures 1 et 2, dans une troisième configuration ;
• - les figures 4 et 5 sont des vues en élévation d'explication de l'utilisation du fauteuil des figures 1 à 3 ;
• - la figure 6 est une vue de l'arrière du fauteuil représenté en élévation sur la figure 5 ; et,
• - les figures 7, 8 et 9 sont des coupes de détails dudit fauteuil.

Reference will be made to the accompanying drawings, in which:

• - Figure 1 is an elevational view of a chair according to the invention, in a first configuration;
• - Figure 2 is an elevational view of an enlarged detail of the chair of Figure 1, in a second configuration;
• - Figure 3 is a perspective view of the chair of Figures 1 and 2, in a third configuration;
• - Figures 4 and 5 are elevational explanatory views of the use of the chair of Figures 1 to 3;
• - Figure 6 is a rear view of the chair shown in elevation in Figure 5; and,
• - Figures 7, 8 and 9 are detail sections of said chair.

• - un support inférieur 1, éventuellement pliant, mais rigide dans la configuration d'utilisation représentée,
• - un dossier 2, qui, toujours dans cette configuration d'utilisation, est fixe par rapport au support 1,
• - un siège 3,
• - deux grandes roues arrière 4, rotatives autour d'axes horizontaux 5, et chacune, munie d'un frein 6,
• - deux petites roues avant 7, montées rotatives sur des chapes 8 autour d'axes horizontaux 9, lesdites chapes étant elles-mêmes montées rotatives sur le support 1 autour d'axes verticaux 10 au moyen de roulements 11.

The armchair shown has a classic frame made up of:

• a lower support 1, optionally folding, but rigid in the configuration of use shown,
• - a folder 2, which, still in this configuration of use, is fixed relative to the support 1,
• - a seat 3,
• - two large rear wheels 4, rotating around horizontal axes 5, and each one provided with a brake 6,
• - two small front wheels 7, rotatably mounted on yokes 8 around horizontal axes 9, said yokes being themselves rotatably mounted on the support 1 around vertical axes 10 by means of bearings 11.

In a manner also known, a section 12 of hollow cylindrical tube is welded to the rear of the support 1, on each side of the seat 3, and allows the introduction of a plug for fitting a removable armrest. Near the transverse plane containing the axes 10, are arranged, fixed to the support 1, two vertical pins oriented upwards 13, which allow the attachment of the frame of a footrest and the pivoting mounting around the vertical pins 13 of said footrest (a footrest mounted on each front side upright of the support 1).

• - une structure mobile 14, généralement plane et contenue dans un plan vertical S placé entre une grande roue a r rJsre 4 et le bord adjacent du siège 3,
• - le support articulé 15 d'un repose-pieds 16.

The devices proposed by the invention are adapted to their mounting on the known frame. It is essentially, on each side of the vertical plane of symmetry P of the chair, to place:

• a mobile structure 14, generally flat and contained in a vertical plane S placed between a large rear wheel 4 and the adjacent edge of the seat 3,
• - the articulated support 15 of a footrest 16.

Each structure 14 comprises an arm 17, the end 18 of which is provided with a hinge pin 19 which extends perpendicular to the plane S of the structure, and which is capable of being rotatably placed in a bearing 20 integral with a adapter plate 21. The end 22 of the axis 19 is grooved and allows maintain the axis 19 in the bearing 20 in cooperation with unoirclips 23. Each adapter plate 21 is fixed (24) on the support 1 near each bearing 11, and then extends parallel to the plane S. In this position of the adapter plate 21, the axis 25 of the bearing 20 is horizontal transverse and coincides with the geometric axis of pivoting of the articulation axis 19. Thus, the structure 14 is pivotally mounted in the plane S fixed by relative to the support 1. Each structure 14 can therefore pivot around the corresponding articulation axis 19, and occupy two very different positions, that of FIG. 1, and that of FIG. 2. To be defined, this structure is d 'first described with reference to the first position of Figure 1.

• - un premier cadre rigide constitué par un quadrilatère à deux barres horizontales, -une barre inférieure 26 et une barre supérieure 27-, cette dernière supportant un accoudoir 28 ; deux barres verticales, avant 29 et arrière 30 complètent le quadrilatère ;
• - un deuxième cadre également rigide constitué par la barre verticale arrière 30, prolongée, du premier cadre, une autre barre verticale 31 située en arrière de la barre 30, une barre inférieure horizontale 32 et une barre supérieure 33 légèrement oblique par rapport à l'horizontale, qui aboutit à l'arrière de la barre supérieure horizontale 27 du premier cadre, donc, à l'arrière de l'accoudoir 28.

In this position, the structure 14 includes:

• a first rigid frame constituted by a quadrilateral with two horizontal bars, a lower bar 26 and an upper bar 27, the latter supporting an armrest 28; two vertical bars, front 29 and rear 30 complete the quadrilateral;
• a second frame, also rigid, constituted by the rear vertical bar 30, extended from the first frame, another vertical bar 31 located behind the bar 30, a horizontal lower bar 32 and an upper bar 33 slightly oblique to the horizontal, which ends at the rear of the horizontal upper bar 27 of the first frame, therefore, at the rear of the armrest 28.

A small cylindrical support 34 is introduced into the tube section 12 and carries, at its upper part., A U-shaped part 35, between the branches of which the rear part of the lower horizontal bar 26 of the first frame rests. The bar 26 is placed substantially at the same height as the seat 3, and the first frame occupies, finally, substantially the same place as the frame of a normal armrest. On the other hand, the entire second frame 30-31-32-33 is placed behind the backrest 2, so as not to cause any discomfort to the user and is substantially contained in the maximum size of a conventional armchair.

Also note the presence of two bars 36 and 37 which are pivotally mounted, one, 36, around the axis of the upper bar 33 of the second frame, substantially in the area of junction of the bars 31 and 33, the another bar, 37, around the axis of the lower bar 32, near the junction of the bars 32 and 31. In the embodiment shown, there is a bar 36 and a bar 37 for each structure 14. Each bar 37 is provided at its end with a cushion 64 and controlled by a lever 65. The lengths 1 and L of the bars 36 and 37, respectively, will be specified below.

• - une barre verticale 38, munie d'oreilles espacées 39 qui en permettent le montage pivotant sur le support inférieur 1 au moyen des ergots verticaux 13,
• - une autre barre 40 d'inclinaison variable, proche de la verticale, placée devant la barre 38 et reliée à celle-ci par deux barres de liaison 41, 42 articulées autour d'axes 43, les barres 38, 40, 41 et 42 constituant un quadrilatère déformable,
• - une barre diagonale 44 articulée, d'une part, autour d'un des axes 43, sommets dudit quadrilatère, d'autre part, sur un taquet pivotant 45, autour d'un axe 46, ce taquet 45 étant monté pivotant sur la barre 40 autour de l'axe 43 opposé au premier axe 43 d'articulation de la barre diagonale 44,
• - deux leviers 47 de commande du pivotement du taquet, ce pivotement permettant de déplacer légèrement en hauteur l'axe 46,
• - une butée 48 que comporte le taquet 45 et qui est susceptible de venir en appui sur la barre diagonale 44 et de la bloquer dans la position de la figure 2,
• - une dernière barre 49, coudée en L, qui est soudée, par l'une de ses branches, à la barre 40, et dont l'autre branche s'étend parallèlement à ladite branche 40, vers le bas.

The support 15 of a footrest comprises:

• a vertical bar 38, provided with spaced ears 39 which allow the pivoting mounting thereof on the lower support 1 by means of the vertical lugs 13,
• another bar 40 of variable inclination, close to the vertical, placed in front of the bar 38 and connected to the latter by two connecting bars 41, 42 articulated around axes 43, the bars 38, 40, 41 and 42 constituting a deformable quadrilateral,
• a diagonal bar 44 articulated, on the one hand, around one of the axes 43, vertices of said quadrilateral, on the other hand, on a pivoting cleat 45, around an axis 46, this cleat 45 being pivotally mounted on the bar 40 around the axis 43 opposite the first axis 43 of articulation of the diagonal bar 44,
• two levers 47 for controlling the pivoting of the cleat, this pivoting allowing the axis 46 to be moved slightly in height,
• a stop 48 which comprises the cleat 45 and which is capable of coming to bear on the diagonal bar 44 and of blocking it in the position of FIG. 2,
• - A last bar 49, bent in L, which is welded, by one of its branches, to the bar 40, and the other branch of which extends parallel to said branch 40, downwards.

Necklaces 50, of which the footrest 16 is integral, are slidably mounted on the bars 40 and 49, and are provided with screws 51 for locking in position relative to the said bars, adjusting the distance of the footrest by relative to the ground 52. The lower ends 40a and 49a of the bars 40 and 49 constitute the support feet on the ground of the support 15, and, depending on the pivoting of the cleat 45, are either out of the ground support 52 (FIG. 1 ), or in firm support on the ground 52 (Figure 2), even slightly lifting the support 1 (and the front wheel 7 which is coupled to it) relative to the ground. In this latter configuration, the stop 48 is effectively supported on the diagonal bar 44, which stiffens the quadrilateral of the bars 38, 40, 41, 42. In addition, each footrest is provided with lower screws 53 which allow the direct support on the ground 52.

Note that the brake 6 of the rear wheels 4 is applied in the configurations of Figures 1 and 2, and that, therefore, the chair is already immobilized.

• - la barre 31, horizontale, à une distance H du repose-pieds 16 correspondant à l'appui normal sur cette barre de la main et de l'avant-bras d'un utilisateur placé debout sur le repose-pieds (figure 5),
• - la barre 32, sensiblement verticale, à proximité du plan vertical transversal T passant par le bord avant 3a du siège 3,
• - la barre 33, sensiblement verticale, en avant de la barre 32.

In the configuration of Figure 2, each movable structure 14 has been pivoted about its axis 19 by about 90 °. The bars of the second frame came, respectively:

• - the bar 31, horizontal, at a distance H from the footrest 16 corresponding to the normal support on this bar with the hand and forearm of a user standing on the footrest (Figure 5) ,
• the bar 32, substantially vertical, near the transverse vertical plane T passing through the front edge 3a of the seat 3,
• - the bar 33, substantially vertical, in front of the bar 32.

The armrest 28 is vertical in a position of non-use as such. As already indicated, the support of the footrest is supported on the ground 52 by the ends 40a and 49a of two of its bars, and it should be observed that the bar 26 of the first frame of the structure 14. is itself resting on the bar 41 of the support 15 of the footrest, and, is maintained in this position by a lock 56 provided with a control button 57 (refer to the constitution of this device, in FIG. 8). An angle 26a, parallel to the end of the bar 26, reinforces this locked support.

Thus, in this second position of the footrest 16 and of the pivoting structure 14, a rigid assembly 15-16-14 has been placed in firm support on the ground 52.

A collar 58 fixed in the middle of each bar 26 allows the fixing of a band of resistant fabric 59 between the two bars 26, this in a removable manner, a first end 59a of the band 59 being fixed, for example permanently, on one of the bars 26, and, the other end 59b of this strip 59 being fixed on the other bar 26 by a removable fixing of the "seat belt" type of a vehicle. The strip 59 preferably has one of its faces in "VELCRO" fabric, allowing the rapid fixing of an elongated cushion 60 substantially at the same height as the seat 3 and, in fact, at the height of the knees d 'a user installed in the wheelchair (Figures 3, 4 and 5).

The use of the new provision is as follows.

The user is seated in the wheelchair placed in its rolling configuration (Figure 1). He immobilizes his chair by means of the brakes 6 of the two rear wheels 4. Then, he lowers his two footrests 16 by pivoting the levers 47 for adjusting the position of the supports 15, and places these supports 15 and footrests 16 in the position of Figure 2. Then, it switches each structure 14 around its axis 19, first by unlocking it (button 57) of the support 1, then relocking it on the corresponding support 15 (Figure 2). It sets up the strip 59 between the bars 26 of the two structures 14 as well as the cushion 60. It is then able to rotate the two bars 36, the length 1 of which corresponds to half the distance separating the two structures 14 , engage the two ends 61, and keep them engaged by a sliding sleeve 62 (Figures 3 and 9). So are stiffened the two structures 14. He can then, with his hands, grasp each structure 14 and, by pulling the arms, and simultaneously taking support, on the one hand, with his feet on the footrests 16, on the other hand, with his knees on the cushion 60, straighten vertically (Figures 4 and 5). To avoid any accident in the event of sudden weakness of the user, the user can, once standing, rotate the bars 37, by about 180 °, to place them between the bars 32 of the two structures 14 (FIGS. 3 and 6), order and lock these bars 37 by means of the lever 65 pivoting on an axis of the bar 31 and a rod 66 connecting this lever to the bar 37 concerned. Note that the length L of each bar 37 is approximately equal to half the distance separating the two structures 14.

Thus, the user, in his standing position, is surrounded laterally by each of the mobile structures 14, at the front by the assembled bars 36, and, at the rear, by the bars 37 and can therefore remain standing in complete safety .

• - en pivotant entre les positions des figures 1 et 2, chaque structure 14 fait basculer la manette 64a de commande du frein 6 correspondant dans le sens du freinage, si cela n'a pas déjà été fait, ce qui implique l'immobilisation préalable, et automatique, du fauteuil, avant la mise en place des structures 14 dans la position de la figure 2 ;
• - de manière analogue, chaque structure 14 ne peut venir en appui sur le support 15 de repose-pieds que lorsque la barre 41 de celui-ci est dans la position de la figure 2, c'est-à-dire dans la position d'appui ferme sur le sol 52 dudit support 15 ;
• - la mise en place des structures 14 dans la configuration de la figure 2 est réalisée par basculement de chacune d'elles autour de son axe 19. Ce basculement, parallèlement aux plans S et P, ne nécessite aucun dégagement voisin du fauteuil et peut donc être réalisé même lorsque les zones voisines du fauteuil sont encombrés ;
• - le bâti même du fauteuil est inchangé par rapport à un fauteuil classique et seules deux pièces spéciales, d'ailleurs aisément et rapidement démontables, ont été ajoutées : les supports cylindriques 34, et, les plaques d'adaptation 21 ; ceci rend économique la réalisation de ce nouveau type de fauteuil ;
• - en position de roulage (figure 1), le gabarit du fauteuil est très sensiblement identique à celui d'un fauteuil classique, et, son utilisation strictement identique à celle d'un fauteuil classique : mêmes fonctions et positions des repose-pieds, des accoudoirs, des siège et dossier ;
• - au moment de se redresser, l'utilisateur tire sur les structures 14 (figure 4) soit sur les barres 31, soit même sur les barres 36 qui assurent alors, non seulement la liaison de rigidification des deux structures, mais aussi l'appui de traction permettant le redressement de l'utilisateur.

It should also be noted that:

• - by pivoting between the positions of FIGS. 1 and 2, each structure 14 switches the handle 64a for controlling the corresponding brake 6 in the direction of braking, if this has not already been done, which implies prior immobilization, and automatic, from the chair, before the structures 14 are placed in the position in FIG. 2;
• - Similarly, each structure 14 can come to bear on the support 15 of the footrest only when the bar 41 thereof is in the position of Figure 2, that is to say in the position d 'firm support on the ground 52 of said support 15;
• - The establishment of the structures 14 in the configuration of Figure 2 is achieved by tilting each of them around its axis 19. This tilting, parallel to the planes S and P, does not require any clearance near the chair and can therefore be carried out even when the neighboring areas of the wheelchair are congested;
• - The frame of the chair itself is unchanged compared to a conventional chair and only two special parts, which are easily and quickly removable, have been added: the cylindrical supports 34, and, the adapter plates 21; this makes it economical to produce this new type of armchair;
• - in the rolling position (Figure 1), the size of the chair is very substantially identical to that of a conventional chair, and its use strictly identical to that of a conventional chair: same functions and positions of the footrests, armrests, seat and backrest;
• - when straightening, the user pulls on the structures 14 (FIG. 4) either on the bars 31, or even on the bars 36 which then ensure not only the stiffening connection of the two structures, but also the support of traction allowing the recovery of the user.

The invention is not limited to the embodiment described, but on the contrary covers all the variants which could be made to it without departing from its scope or its spirit.

In particular, it is obvious that the two structures 14 could be replaced by a single, arched structure.

Claims (10)

1. Wheelchair allowing the recovery of its user, in particular for use by a paraplegic, comprising: a frame (1) resting on the ground (52) by means of front (7) and rear (4) displacement members and supporting a seat (3), and, - a mobile structure (14) separate from said seat and capable of occupying the following two positions: . a first position, in which this structure is retracted so as, on the one hand, to leave at least the space located in front of the seat (3) clear, on the other hand, to maintain the possibilities of rolling of the chair, and , . a second position, in which this structure (14), on the one hand, is placed in said space located in front (T) of the seat (3) while being accessible to the hands of a user seated in the chair, d on the other hand, rests on the part of the ground located in front of said seat,
characterized in that the structure comprises two frames (14) which extend substantially parallel to the sides of the chair, one frame on each side of this chair, and which are pivotally mounted on the frame around transverse horizontal axes (19) which allow it to tilt forwards substantially 90 ° during which is moved a set of bars (30-31-32-33) which are arranged, initially, in the first position of the structure, behind (2) of the seat (3), and which, in the second position of this structure, are arranged in the space located in front (T) of said seat (3). 2. Chair according to claim 1, characterized in that, in its first position, the structure has a space (28) lateral, on each side of the seat and in the space above the seat, which is substantially that of the usual wheelchair frame. 3. Chair according to any one of claims 1 and 2, characterized in that it comprises a footrest (16), which is mounted on the frame (1), movable (15) relative to this frame, and capable of occupying two positions, one, corresponding to the possibilities of rolling the chair, in which it is located above the ground , (52), without being in contact there, the other position, corresponding to the second position of the structure, in which it is in firm support on the ground (52) and lifts the front displacement members (7) of the chair , while the two said frames (14), in this second position of the structure, are in abutment (26a) on said footrest (16). 4. Chair according to claim 3, characterized in that a locking device (45-47) allows the blocking of the footrest (16), in its support position on the floor. 5. Chair according to any one of claims 3 and 4, characterized in that another locking device (56-57) realizes, in the second position of the structure, the joining of each of the two frames (14) on the footrest (15). 6. Chair according to any one of claims 1 to 5, characterized in that the structure comprises a device (59-60) for supporting the knees, which is at least partially removable (58b), and which, in the second position of the structure, extends horizontally transversely, at the height of the knees of a wheelchair user. 7. Chair according to any one of claims 1 to 6, characterized in that the structure comprises a movable element (37) which, in the second position of this structure, is capable of being placed horizontally transversely, substantially near the vertical plane (T) passing through the front edge (3a) of the seat (3), being disposed at a height at least equal to that of the pelvis of a user placed upright on the footrest (16) of said chair, and which is separate from the seat of the chair, said seat having a fixed position relative to the frame in the first and second positions of the structure. 8. Chair according to any one of claims 1 to 7, characterized in that, in the second position of the structure, the two frames (14) are connected by a rigid element removable (36-62), which, in this second position, is arranged horizontally and transversely and ensures the stiffening of this structure. 9. Chair according to claim 8, characterized in that said rigid element (36-62), in the second position of the structure, extends substantially at the height of the trunk of a user seated in the chair. 10. Armchair according to any one of claims 1 to 9, characterized in that each frame (14) is kept pivoting about its axis (19) by a device (18-22-23) for rapid assembly and disassembly.

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