AN ADJUSTABLE CHAIR

Abstract: An adjustable chair is described comprising a body (2) supported by a base (4) and having a frame (3) constituted by two parts (9) and (10) hingedly connected together. The main characteristic of the present invention lies in the fact that it includes a mechanism (31) having a first body (32) hinged about a pin (44) rigidly connected to the base (4) and having its front end rigidly connected to the part (9) associated with the seat (8), and a second body (55) and (56) having a rear end (56) fixed to the part (10) associated with the seat back (7) and a front end connected, by spring means (54), to a central portion (35) of the said first body (32).

Description: The present invention relates to an adjustable chair. In particular, the present invention relates to an adjustable chair of the type described in FR-A-2 509 160, and comprising a base; a body supported by such base; and a control mechanism for controlling the position of the above body in relation to the base; and in which the body includes a frame, which comprises a first part defining a seat, a second part defining a seat back, and a hinge for connecting the above first and second parts together so as to allow relative rotation thereof about an axis; the aforementioned mechanism having a first member, a pin extending parallel with the above axis of rotation and connected to the base to form a pivot for the above first member to rotate thereabout, and a second member having a rear portion connected to the second part of the frame. In the known chairs of the type described hereinabove, the aforementioned second member has a front end hinged to the base, and the aforementioned first member is a resilient member extending between the base and an intermediate point of the second member to resiliently control the rotation thereof in relation to the base. The above known chairs in general, and the chair disclosed in FR-A-2 509 160 in particular, suffer from the drawback of comprising substantially one single part, that is the seat back, which is displaceable in dependence on the forces applied thereto, whereas the other part, that is the seat, remains substantially motionless whatever the distribution of the above forces may be. In other words, the above known chairs are not real adjustable chairs, in the sense that only a part thereof is deformable in dependance on the distribution of forces applied thereto, i.e. on the position of the user; whereas the theory is perfectly known that in a real adjustable chair, all the component parts should be deformable to suit, in any case, the position of a user. In particular, in an adjustable chair, not only both the angles between seat and seat back and between the seat back and the supporting base should change to suit the user's position, but also the angle between the seat and the base should change, and the variations of the angles of the seat and the seat back in relation to the base should be dependent on one another according to a law in turn depending on the weight of the user. In another type of known chairs disclosed in GB-A-2 001 241, the seat and the seat back are substantially rigid with each other, and are mounted on a base to pivot in relation thereto about a single pivot, so that the angles between the seat and the base, and between the seat back and the base change, but not the angle between the seat and the seat back. Also the chairs of this known type are not, therefore, real adjustable chairs. It is an object of the present invention to provide an adjustable chair having a very simple structure and relatively low production costs. According to the present invention there is provided an adjustable chair comprising a base; a body supported by said base; and a control mechanism for controlling the position of said body in relation to said base; said body including a frame, which comprises a first part defining a seat, a second part defining a seat back, and hinge means for connecting said first and second parts together so as to allow relative rotation thereof about an axis; said mechanism having a first member, a first pin extending parallel with said axis and connected to said base to form a pivot for said first member to rotate thereabout, and a second member having a rear portion connected to said second part, characterized in that said first member has a front end rigidly connected to said first part; a second pin parallel to said first pin being carried by a central portion of said first member, and said second member having a front end coupled to said second pin for rotation thereabout in relation to said first member, and against the action of spring means. In the adjustable chair set forth above, the seat is hinged to the seat back, and is connected to the first member of the mechanism for rotating substantially therewith in relation to the base and about a first axis, whereas the seat back is connected to the second member of the mechanism and hinged to the first member of the mechanism to rotate in relation to the above first member about a second axis. Owing to the presence of such second axis, the seat and the seat back on one hand, and the first and the second member of the mechanism on the other hand substantially define an articulated parallelogram allowing movement of the seat and the seat back in relation to each other and to the base as theoretically required in an adjustable chair. The invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a preferred embodiment of the adjustable chair according to the present invention; Figure 2 is a longitudinal partial section, on an enlarged scale, of the chair of Figure 1; Figures 3 and 4 are a plan view and a front view respectively of a particular of the chair of Figure 1; and Figure 5 is a perspective view of the chair of Figure 1 in which the possible movements thereof are illustrated. As illustrated in Figure 1, an adjustable chair is generally indicated with the reference numeral 1 and comprises a body 2 having a metal frame 3 (Figure 2) completely embedded in a layer of polyurethane which will be described better hereinbelow. The body 2 rests on a base 4 of the type having five radial arms 5 to the free ends of which are fixed respective wheels 6. The body 2 is defined by a seat back 7 and a seat 8 which can assume a respective inclination according to the position assumed by the user. The chair 1 can be adjusted in dependence on the fundamental anthropometric parameters of the user such as height and weight. The chair 1 is able automatically to favour the position assumed by the user in that it includes mechanisms which allow the inclination of the seat back 7 and of the seat 8 and which are actuated by the pressure of the body of the user. With reference to Figures 2, 3 and 4, the part of the frame 3 relating to the seat 8 is indicated 9 and includes a rod bent into a U in such a way as to define tow lateral bars 11 and a front bar 12. The free ends of the bars 11 are connected together by a rear bar 13 parallel to the bar 12. The free ends of the bars 11 are pivoted to a respective pin 15. The part of the frame 3 associated with the seat back 7 is indicated 10 and comprises two rods folded to form a parallelogram. These rods define a respective outer lateral bar 16, a respective inner lateral bar 18 and two bars 22 and 23 which are, respectively, upper and lower bars, joining the bars 16 and 18, which are parallel to one another. The bar 18 has a length less than that of the bar 16 and the bars 22 and 23 are oblique with respect to the bars 16 and 18. The free ends of the bars 16 are pivoted to the pins 15. The bars 18 are connected together by a bar 21 whilst the bars 22 are connected together by a spring 24. As illustrated in Figures 2, 3 and 4 a mechanism mounted on the frame 3 is generally indicated 31 and is able to allow the inclination of the seat back 7 and the seat 8. The mechanism 31 comprises a plate 32 having a front end fixed to a bar 33 rigidly connected to the bar 12. A plate 32 has, starting from the bar 33, a first section 34 which extends downwardly, a central second section 35 which also extends downwardly but with a different inclination from that of the section 34, and a third section 36 lying in a plane substantially parallel to the support plane of the chair 1. In the section 36 there is formed a central through hole 37 housing an upper end 38 of the base 4 within which there is mounted, in a manner not illustrated, a gas cylinder by actuating of which one can regulate the longitudinal extension of the base 4 and therefore the height of the body 2 above the support plane. The end 38 of the base 4 engages a sleeve 41 having above and below the plate 32 respective sections 42 and 43. The section 43 supports, close to the junction between the sections 35 and 36 of the plate 32, a small bar 44 the axis of which is parallel to the support plane and to the bar 12. From the section 36 of the plate 32 two pierced projections 49 extend downwardly, by means of which the plate 32 is pivotally connected to the bar 44. The plate 32 can therefore rotate about the axis of the bar 44. The section 43 has an outer diameter greater than that of the section 42. Along the section 43 of the sleeve 41 there is formed a through hole 45 coaxial with the through hole 46 formed in the section 36 of the plate 32 close to the free end of this. The holes 45 and 46 house a screw 47 and stem of which extends upwardly and out from the hole 46 and lodges in a sleeve 48 formed of resilient material. To the stem of the screw 47 there is screwed a nut 51 which, by means of a washer, compresses the sleeve 48 onto the upper face of the plate 32 which has two lateral projections 52 which extend upwardly. In correspondence with the connection between the sections 35 and 36 there is fixed to the lateral projection 52 a pin 53 around the two ends of which there is wound a respective spring 54. The mechanism 31 further includes two parallel bars 55 having a first end fixed to a U-shape element 56 the concavity of which faces upwardly. From the bars 18 extend respectively pins 57 which lodge in corresponding ends of the element 56. The bars 55 are thus hinged to the pins 57. The element 56 is engaged by a strip 58 of plastics material fixed thereto by means of screws not illustrated. The strip 58 prevents the escape of the pins 57 from the element 56. The bars 55 have a first section 61 positioned between the bars 18, a second section 62 which extends from the first beneath the part 9, and a third section 63 which is parallel to and positioned above the section 36 of the plate 32. At the free ends of the sections 63 there is fixed one end of a corresponding spring 54 a second end of which is folded and housed in a sleeve 65 also housing a second end of the spring 54. The sleeve 65 has an axis parallel to that of the pin 53 and is positioned between the projections 52 extending from the section 35 of the plate 32. The sleeve 65 has a central diametral threaded hole 66 in which is screwed the shank of a screw 67 the head of which rests beneath the section 35 and which extends upwardly through a through hole 71 formed in the section 35. At the junction between the second section 62 and the section 63 of the bars 55 these are connected by bars 72 from which extend two parallel plates 73 which have at their free ends respective holes housing the pin 53. The springs 54 are compressed between a plate 73 and a corresponding projections 52. The part 9 can be provided with a network of elastic belts 75 illustrated in broken outline (Figure 3). As illustrated in Figures 1 and 2, in use, once the frame 3 has been prearranged, the parts 9 and 10 are embedded in respective layers of polyurethane 80 and 81 in such a way as to define together therewith the seat back 7 and the seat 8. The layer of polyurethane 80 of the seat back 7 has a U-shape cut 82 corresponding to the element 56 and to the bars 55. These latter, in correspondence with their first section 61, are embedded in a layer of polyurethane 83 having a plurality of corrugations parallel to the support planes. The layer 81 has a central portion 84 having a plurality of corrugations parallel to those of the layer 83. The portion 84 extends from the bar 13 into the bar 12 and has for a substantial section the same width as the layer 83 and subsequently an increasing width. It is to be noted moreover that the sections 62 and 63 of the bars 55 and the space defined by the plate and by the projections 52 are also embedded in a layer of polyurethane 86 which also covers the lower face of the plate 32 (Figure 2). The layer 86 is formed as a continuation of the layer 83. Along the whole of the junction between the layers 80 and 81 there is formed an open slot 87. The layers 80 and 81 finally have a lateral edge 88 of greater thickness. With reference to Figure 5, the inclination of the seat back 7 and of the seat 8 is a function of the distribution of the weight of the body of the user. In particular, when almost all of the weight of the user is exerted on the seat 8 separating its back from the seat back 7 a rotation of the plate 32 in a clockwise sense takes place about the axis of the bar 44. This rotation causes rotation in a clockwise sense also of the whole of the body 2. The free end of the plate 32 in correspondence with the hole 46 will also turn in a clockwise sense compressing the sleeve 48. As soon as the pressure of the body on the seat 8 ceases, as has just been described, the whole body 2 returns to the original position by the action of the sleeve 48 which presses the free end of the plate 32 downwardly making this latter turn in a clockwise sense. With the back engaging on the seat back 7 rotation of the bar 55 about the axis of the pin 53 takes place by deformation of the springs 54. Finally the seat back 7, and in particular the part 10 of the frame 3, turns about the axes of the pins 57 and draws the pins 15 downwardly with a movement of pantograph type. Consequently this increases the relative angle between the seat 8 and the seat back 7. By means of the screw 67 the springs 54 can be calibrated, that is to say more or less preloaded for the purpose of adjusting the rotation of the bars 55 in relation to the weight of the user. The chair 1 can be provided with a covering 91 (Figure 5). The numerous advantages following on the structure of the present invention will be evident. In particular, the chair 1 can be personalised by adjusting the mechanisms 31 (screws 67) in dependence on the weight of the user. Moreover, in dependence on the position assumed, the inclination of the seat back 7 and of the seat 8 which accompanies the body of the user takes place automatically. The mechanism 31 which permits such inclination is of simple construction in that it is formed with a small number of components. It is to be noted that the frame 3 and the mechanism 31 are embedded in polyurethane which forms the aesthetic outline of the chair 1, which for the considerations just explained is of reduced production costs. The parts 9 and 10 can have lateral projections in such a way as to be able to widen the body 2 at will starting from a base model of the frame 3. In place of the polyurethane there can be used other resilient and/or deformable materials such as a different plastics material, rubber or a sponge layer.

Claims: An adjustable chair comprising a base (4); a body (2) supported by said base (4); and a control mechanism (31) for controlling the position of said body (2) in relation to said base (4); said body (2) including a frame (3), which comprises a first part (9) defining a seat (8), a second part (10) defining a seat back (7), and hinge means (15) for connecting said first and second parts together so as to allow relative rotation thereof about an axis; said mechanism (31) having a first member (32), a first pin (44) extending parallel with said axis (15) and connected to said base (4) to form a pivot for said first member (32) to rotate thereabout, and a second member (55,56) having a rear portion (61) connected to said second part (10), characterized in that said first member (32) has a front end rigidly connected to said first part (9); a second pin (53) parallel to said first pin (44) being carried by a central portion (35) of said first member (32), and said second member (55,56) having a front end coupled to said second pin (53) for rotation thereabout in relation to said first member (32), and against the action of spring means (54). A chair as claimed in Claim 1, characterized in that said first member (32) includes a plate (32) having a pair of first lateral projections (52) on which said second pin (53) is mounted; said spring means (54) being wound about said second pin (53) and coupling together said second member (55) and the central portion (35) of said first member (32). A chair as claimed in Claim 2, characterized in that the said second member (55) includes bars (63) having respective free ends; said spring means (54) being connected to said free ends; and adjustable-length link means (67) being provided to connect said spring means (54) to the central portion (35) of said first member (32). A chair as claimed in any one of the preceding Claims, characterized in that said first pin (44) is coupled to said first member (32) substantially at the central portion (35) thereof; said first member (32) including a rear portion (36) extending beyond said first pin (44), and resilient means (45,48) being provided to couple said rear portion (36) to said base (4) to control rotation of said first member (32) about said first pin (44) in relation to said base (4). A chair as claimed in any one of the preceding Claims, characterized in that an intermediate pin member (57) parallel with said axis is provided on said second part (10) of said frame (3), being hinged to said intermediate pin member (57). A chair as claimed in any one of the preceding Claims, characterized in that a pair of first layers (81,80) of polyurethane are provided, in which said first and second parts (9, 10) are respectively embedded. A chair as claimed in Claim 6, characterized in that a second layer (83,86) of polyurethane is provided, in which said mechanism (31) is embedded. A chair as claimed in Claim 7, characterized in that that (80) of said first layers (81,80) which embeds said second part (10) is provided with an aperture (82) along which the rear portion (61) of said second member (55) extends together with a relevant rear portion (83) of said second layer (83,86); a number of corrugations parallel with said axis (15) being provided on a front surface of said rear layer-portion (83). A chair as claimed in Claim 8, characterized in that said first layer (81) in which the said first part (9) is embedded has a central portion (84), which is aligned with said rear layer-portion (83), and on which a number of further corrugations are formed parallel with said axis (15).

Inventors: GAMBERINI, GINO
Applicants: C.O.M. COOPERATIVA OPERAI MOBILIERI S.C.R.L.
Application year: 1986
Main classification: A47C1
IPC codes: A47C1