EP2110051A1

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Publication number: EP2110051A1
Application number: EP08425266A
Authority: EP
Inventors: Alessandro Piretti
Original assignee: Pro Cord SpA
Current assignee: Pro Cord SpA
Priority date: 2008-04-18
Filing date: 2008-04-18
Publication date: 2009-10-21
Also published as: US20090261644A1

Abstract

A chair comprising two ribbed supporting sectional elements (12) set at a distance from one another in a transverse direction and connected to a base (22, 24) by means of a transverse supporting element (20), wherein each of said ribbed supporting sectional elements (12) is basically L-shaped, with a seat portion (12a), a backrest portion (12b), and a rounded radiusing portion (12c) between the seat portion (12a) and the backrest portion (12b), wherein extending between said supporting sectional elements (12) is a material basically in the form of a sheet (42, 62), which forms a seat (42a, 62a) and a backrest (42b, 62b), and wherein each of said ribbed supporting sectional elements (12) is provided with a plurality of through notches (48) set at a distance from one another in a longitudinal direction, which form respective points of localized bending, which enable bending of the supporting sectional element (12) in a vertical plane, said notches (48) distanced from one another by respective stretches (50) substantially rigid to bending in said vertical plane.

Description

Field of the invention

The present invention relates to a chair comprising two ribbed supporting sectional elements set at a distance from one another in a transverse direction and connected to a base by means of a transverse supporting element, in which each of said ribbed supporting sectional elements is basically L-shaped with a seat portion, a backrest portion, and a rounded radiusing portion between the seat portion and the backrest portion and in which a substantially sheet-like material forming a seat and a backrest extends between said ribbed supporting sectional elements.

Description of the related art

A chair of the type referred to above is known from the document No.DE1260721 filed in the name of Hermann Miller Inc. The chair described in this document was made by the famous designer Charles Eames in 1958 and became a point of reference of industrial design.
The chair designed by Charles Eames envisaged the use of two basically I-section rigid aluminium supporting sectional elements fixed together by means of at least two transverse supporting elements, one of which serves for connection to a column base. A sheet formed by a fabric or a mesh, is wound on the two lateral aluminium sectional elements and is anchored laterally in two external side grooves of the supporting sectional elements.

Summary of the invention

The purpose of the present invention is to provide a chair that will enable higher characteristics of comfort to be obtained, maintaining the same stylistic setting of the chair designed by Eames in 1958.
According to the present invention, the above purpose is achieved thanks to the fact that each of the ribbed supporting sectional elements is provided with a plurality of through notches, which are set at a distance from one another in a longitudinal direction and form respective points of localized bending of the supporting sectional element in a vertical plane, said notches being set at a distance from one another by respective stretches that are substantially rigid to bending in said vertical plane.
By making the supporting sectional elements of plastic material (typically nylon) and forming the aforesaid notches in a central stiffening ribbing of the sectional elements, there is the possibility of introducing a controlled bending in definite portions of the sectional element. Bending of the sectional element can be assisted by a small steel bar inserted in a groove of the sectional element in an area corresponding to the radiusing area between the seat portion and the backrest portion of each sectional element.
The notches have opposite surfaces that enter into contact with one another in the position of maximum inclination so as to limit the maximum amount of localized bending in each point of the sectional element.

Description of the drawings

The present invention will now be described in detail with reference to the attached drawings, which are provided purely by way of non-limiting example and in which:

Figure 1 is a perspective view of a first embodiment of a chair according to the present invention;
Figure 2 is an exploded perspective view of the chair ofFigure 1;
Figure 2A is a cross section according to the line II-II ofFigure 2;
Figure 3 is a cross section according to the line III-III ofFigure 1;
Figure 3A is an enlarged detail of a part ofFigure 3;
Figure 4 is a detail at a larger scale of the part indicated by the arrow IV inFigure 2;
Figure 5 is a view of the detail ofFigure 4 illustrating the notches in the position of maximum bending;
Figure 6 is a schematic side view illustrating the radiusing portion of a supporting sectional element in the resting position and in the position of maximum inclination backwards;
Figure 7 is a detail illustrating notches of different shape;
Figures 8 and 9 are sections according to the lines VIII-VIII and IX-IX ofFigure 4 illustrating an alternative shape of the ribbing of the supporting sectional elements;
Figure 10 is a perspective view illustrating a second embodiment of the chair according to the present invention;
Figure 11 is a perspective view of the supporting structure of the chair ofFigure 10;
Figures 12 and 13 are sections according to the lines XII-XII and XIII-XIII, respectively, ofFigure 10;
Figure 12A is an enlarged detail of a part ofFigure 12;
Figure 14 is a perspective view of a third embodiment of the chair according to the present invention;
Figure 15 is an exploded perspective view of the chair ofFigure 14;
Figure 16 is a cross section according to the line XVI-XVI ofFigure 14;
Figures 17 and 18 are sections according to the lines XVII-XVII and XVIII-XVIII ofFigure 15 illustrating an alternative embodiment of the ribbed sectional elements;
Figure 19 is a perspective view of a fourth embodiment of the chair according to the present invention; and
Figure 20 is a perspective view of a further variant of the seat-backrest assembly of the chair according to the present invention.

Detailed description of the preferred embodiments

With reference toFigures 1 and2, designated by 10 is a chair according to a first embodiment of the present invention. Thechair 10 comprises two ribbed supportingsectional elements 12 that form the side edges of thechair 10. The two supportingsectional elements 12 are arranged parallel to one another and are set at a distance from one another in a transverse direction. The two supportingsectional elements 12 are preferably identical to one another and each of them is basically L-shaped, with aseat portion 12a, abackrest portion 12b and an arched radiusingportion 12c, which extends between theseat portion 12a and thebackrest portion 12b.
Each supportingsectional element 12 is constituted by a monolithic element made of injection-moulded plastic material, for example nylon. As may be seen in particular inFigure 3, each supportingsectional element 12 has anexternal groove 14 and aninternal groove 16. The twogrooves 14, 16 extend continuously throughout length of each supportingsectional element 12. Each supportingsectional element 12 is moreover provided with aribbing 18 that extends in a vertical plane, made integrally with the respective supportingsectional element 12. Theribbing 18 extends throughout the radiusingportion 12c and over a substantial part of theseat portion 12a and of thebackrest portion 12b. Theribbing 18 extends on the bottom side of theseat portion 12a and on the rear side of thebackrest portion 12b.
With reference toFigures 2 and3, the two supportingsectional elements 12 are fixed to a transverse supportingelement 20 carried by acentral column 22 of abase 24 provided withwheels 26. The transverse supportingelement 20 has twoside portions 28, fixed to which are the two supportingsectional elements 12. In the embodiment illustrated in the figures, fixing of the supportingsectional elements 12 to the transverse supportingelement 20 is made by means ofscrews 30 that engage alignedholes 32, 34 formed in theside portions 28 and in theribbing 18 in an area corresponding to theseat portion 12a of each supportingsectional element 12. The transverse supportingelement 20 is preferably made of metal material, for example die-cast aluminium.
With reference toFigures 2 and2A, the supportingsectional elements 12 are moreover connected to one another by means of a dorsaltransverse element 36, the side ends of which are inserted in theinternal grooves 16 of the two supportingsectional elements 12, at the top ends of therespective backrest portions 12b. The ends of thetransverse element 36 are preferably fixed to thesectional elements 12 by means ofscrews 38, which engageholes 40 provided on the rear part of thesectional elements 12.
With reference toFigures 1 to 3, thechair 10 comprises asheet 42 of flexible material that is tensioned between the two lateral supportingsectional elements 12. The sheet offlexible material 42 is preferably constituted by a single piece of fabric, mesh or the like, which is held by the lateral supportingsectional elements 12 in the configuration illustrated inFigures 1 and2, where thesheet 42 has aseat portion 42a, abackrest portion 42b, and anarched radiusing portion 42c, in an area corresponding to therespective portions 12a, 12b and 12c of the supportingsectional elements 12.
As illustrated in particular detail inFigures 3 and3A, the sheet offlexible material 42 has twoside edges 44, which are inserted and fixed in the respectiveexternal grooves 14 of the supportingsectional elements 12. Preferably, theside edges 44 are sewn so as to form a loop in order to present a tubular seat in which aflexible lamina 46 is inserted. The side parts of the sheet offlexible material 42 wrap around the top part of the supportingsectional elements 12, and theside edges 44 are anchored to the supportingsectional elements 12 in theexternal grooves 14. Fixing of theside edges 44 to the supportingsectional elements 12 can be completed by means of screws. As may be noted inFigure 3, the sheet offlexible material 42 remains tensioned between the side supports 12.
With reference toFigures 4 to 7, theribbing 18 of each supportingsectional element 12 is provided with a plurality of throughnotches 48 set at a distance from one another along the longitudinal axis of theribbing 18. Theribbing 18 of each supportingsectional element 12 extends in a vertical plane of symmetry of the respective supportingsectional element 12. If theribbing 18 were continuous, each supportingsectional element 12 would be basically rigid as regards bending in the vertical plane of symmetry. Thenotches 48 form respective points of localized bending of the supportingsectional elements 12. In an area corresponding to eachnotch 48, the supportingsectional element 12 is able to perform a movement of bending. Thenotches 48 are distanced from one another in a longitudinal direction bystretches 50 in which theribbing 18 is continuous. The supportingsectional element 12 in an area corresponding to thestretches 50 is basically rigid for the movements of bending in the vertical plane of symmetry. Thenotches 48 form hinge points between substantially rigid contiguous sections of the supportingsectional element 12.
With reference toFigure 4, eachnotch 48 comprises a substantially drop-shaped throughhole 52 made in the internal part of theribbing 18. Eachnotch 48 has twodivergent walls 54 facing one another, which extend from thehole 52 to the outer edge of theribbing 18. Thewalls 54 form an angle α that represents the maximum amplitude of the movement of bending in each point of localized bending. In fact, the movement of bending of the supportingsectional element 12 produces a mutual approach of the facing surfaces 54. When thesurfaces 54 are in contact with one another as illustrated inFigure 5, the supportingsectional element 12 becomes rigid in regard to a further deformation of bending. Each point of localized bending of thesectional element 12 is hence self-limiting, with a maximum amplitude of bending defined by the geometry of therespective notch 48.
Figures 4 and5 show in side view a stretch of a supportingsectional element 12 in the resting position and in the position of maximum inclination backwards, respectively. As may be noted, in the position of maximum inclination backwards illustrated inFigure 5 thewalls 54 of eachnotch 48 are in contact with one another, i.e., each point of localized bending is in the position of maximum bending. The fact that the points of localized bending are self-limiting is particularly important in so far as it prevents the risk of an excessive bending from causing yielding of the supportingsectional element 12.
Figure 6 shows theradiusing portion 12c of a supportingsectional element 12 in the resting position (solid line) and in the position of maximum inclination backwards (dashed line). In the position of maximum inclination, the backrest is inclined by approximately 22° with respect to the resting position. The stiffness of the movement of bending of the supporting sectional element depends upon the geometry of thenotches 48. As illustrated by way of example inFigure 7 notches 48' can be provided, which extend throughout the width of theribbing 18 andnotches 48", which extend only through a part of the height of theribbing 18. Thenotches 48" could for example be arranged in the areas in which it is desired to obtain a movement of bending with a higher stiffness. Thenotches 48" could for example have a maximum inclination α'' in the region of 3°, whilst the notches 48' could have a maximum inclination α' in the region of 4°. By varying the geometry of the notches it is possible to vary the flexural stiffness and the maximum angle of inclination in an area corresponding to each point of localized bending. Furthermore, by varying the distance between the contiguous notches, it is possible to vary the geometry of deflection of the supportingsectional elements 12.
In the embodiment illustrated inFigures 1 to 3, theribbing 18 has a rectangular cross section. Theribbing 18 can have a thickness (dimension in the transverse direction) comprised between 2 and 20 mm. Theribbing 18 can have a height (extension in a vertical plane) comprised between 10 and 60 mm.
Illustrated inFigures 8 and 9 is an alternative embodiment of the cross section of the supportingsectional element 12. In this case, theribbing 18 has a substantially parabolic shape with a maximum width equal to the width of thesectional element 12, which can be in the region of 15-40 mm. The height of theribbing 18 can be comprised between 10 and 60 mm.
Eachnotch 48 can have a height comprised between 5 mm and 60 mm. The angle between thedivergent walls 54 of eachnotch 48 can be comprised between 1° and 22°. In general, the angle between thewalls 54 is in the region of 3°-4° so that thenotches 48 are very narrow. Consequently, closing of thenotches 48 during bending of the supportingsectional elements 12 does not entail the risk of pinching of the user's fingers. Whenever necessary, thenotches 48 can be protected by means of co-moulded compressible elastomer elements that close the side and front outer edges of eachnotch 48 partially or completely.
Return from the deflected position to the resting position occurs as a result of the elastic return of the material constituting the supportingsectional elements 12, thanks to the particular elasticity of the plastic material constituting the sectional elements. As illustrated inFigures 2 and3, to increase the characteristics of elastic return of the supportingsectional elements 12, each of said sectional elements can be provided with at least oneelastic member 56. Said elastic member can advantageously be constituted by a small bar of metal material with high elasticity, for example spring steel, inserted in the internal groove 16 (Figure 3) of each supportingsectional element 12. If necessary, there may be provided anelastic member 56 in each of thegrooves 14, 16 of each supportingsectional element 12. Theelastic member 56 can be arranged in theradiusing portion 12c of each supportingsectional element 12 and in any other area in which it is desired to increase the characteristics of elastic return of the sectional element.
Illustrated inFigures 10 to 13 is a second embodiment of the chair according to the present invention. The elements corresponding to the ones previously described are designated by the same reference numbers.
In this embodiment of the invention, the two ribbed supportingsectional elements 12 are connected to one another by twotransverse elements 58, 60 formed integrally by moulding with the supportingsectional elements 12. As illustrated inFigure 11, the two supportingsectional elements 12, connected to one another by thetransverse elements 58, 60, constitute a framework formed by a single piece of injection-moulded plastic material.
The firsttransverse element 58 is set in an area corresponding to the top ends of thebackrest portions 12b. The secondtransverse element 60 is set in an area corresponding to the front end of theseat portions 12a. In this variant, each supportingsectional element 12 can be provided with just one groove (the external groove 14), serving for anchorage of the side edges 44 of the sheet offlexible material 42. The two supportingsectional elements 12 are fixed, in a way similar to that of the embodiment previously described, to a transverse supportingelement 20 of metal material, which is fitted on thecentral column 22 of thebase 24.
This second embodiment enables simplified assembly of the sheet offlexible material 42 on the supportingsectional elements 12. For insertion of the side edges 44 of the sheet offlexible material 42 into theexternal grooves 14 of the supportingsectional elements 12 the flexibility of thetransverse elements 58, 60 is exploited, which enables approach of the supportingsectional elements 12 to one another. After insertion of the side edges 44 in theexternal grooves 14, the supportingsectional elements 12 are brought back into their resting position by the elastic return of thetransverse elements 58, 60, by setting the sheet offlexible material 42 in tension between the supportingsectional elements 12. The structure is definitively stiffened in a transverse direction by fixing of the ribbed supportingsectional elements 12 to the transverse supportingelement 20, as illustrated inFigure 12. Theelastic members 56 can be inserted in the sameexternal grooves 14 in which the side edges of theflexible sheet 42 are inserted (seeFigure 12). Alternatively, there could be provided seats for theelastic members 56 on the internal sides of the supportingsectional elements 12.
Figures 14 to 16 illustrate a third embodiment of thechair 10 according to the present invention. In this case, thechair 10 comprises a shapedthin plate 62 made of injection-moulded plastic material having aseat portion 62a, abackrest portion 62b and anarched radiusing portion 62c. The plate ofplastic material 62 has twointegral ribbings 64 that project in a vertical plane from the bottom or rear surfaces of theportions 62a, 62b, 62c. Theribbings 64 with the corresponding portions of theplate 62 constitute two lateral supportingsectional elements 12, between which the flexible plastic material forming the seat and the backrest of the chair extends. As in the variants described previously, theribbings 64 are provided with throughnotches 48, which form points of localized bending of the supportingsectional elements 12.
Theribbings 64 are fixed to a transverse supportingelement 20 carried by acentral column 20, in a way similar to what was described previously. In the rear surface of theplate 62, in an area corresponding to theradiusing portion 62c, there are preferably made twointegral seats 66 for housing elastic members 56 (see, in particularFigures 15 and16). Theseats 66 can be positioned on the inner side of the ribbings 64 (as illustrated in the figures) or else on the outer side.
The plate ofplastic material 62, in order to be able to bend backwards, must not have a concave curvature on the surfaces of the seat and of the backrest since said curvature would stiffen the backrest, preventing it from bending backwards. For this reason, in this embodiment thechair 10 is preferably provided with padded panels (not illustrated) fixed to the surfaces of the seat and backrest of the plate ofplastic material 62.
Also in this embodiment, theribbings 64 of the supportingsectional elements 12 can have different shapes in cross section. For example, illustrated inFigures 17 and 18 is an alternative embodiment, in which theribbings 64 have a substantially parabolic shape in cross section.
Illustrated inFigure 19 is a variant of the chair ofFigure 14. Also in this case, theribbings 64 are formed integrally with aplate 62 of plastic material. The problem of the impossibility of providing concave resting surfaces of the seat and backrest is solved by forming in theplate 62 a plurality oftransverse openings 68 that extend between the ribbed supportingsectional elements 12. The height of theopenings 68 must be sufficiently wide so as not to constitute a hazard for the fingers of the user during bending backwards of theplate 62. In this embodiment, the seat and the backrest of the chair are formed by two ribbed supportingsectional elements 12 arranged laterally and extending between which is a plurality oftransverse slats 70 parallel to one another and set at a distance from thetransverse openings 68. Theslats 70 can have a concave sectional element so as to provide concave resting surfaces in an area corresponding to theseat portion 62a and thebackrest portion 62b.
In the version illustrated inFigures 14 and19, theribbings 64 do not necessarily need to be positioned in an area corresponding to the side edges of theplate 62. In a possible variant illustrated inFigure 20, theribbings 64 can be displaced laterally towards the median plane of the chair.
The chair according to the present invention enables provision of a flexible seat formed by a fabric or by an elastic mesh or, alternatively, by a sheet of injection-moulded plastic material. The supportingsectional elements 12 can be provided with a large number of points of localized bending distributed along a substantial part of the ribbed sectional elements. In particular, the present invention enables positioning of the points of start of bending in a very advanced position (approximately half of the seat). This characteristic increases comfort for the user considerably as compared to a chair in which the movement of bending backwards regards just the backrest or a portion thereof. The most advanced notch can be set in the immediate vicinity of the area of fixing of the supportingsectional elements 12 to the transverse supportingelement 20.

Claims

A chair comprising two ribbed supporting sectional elements (12) set at a distance from one another in a transverse direction and connected to a base (22, 24) by means of a transverse supporting element (20), wherein each of said ribbed supporting sectional elements (12) is basically L-shaped, with a seat portion (12a), a backrest portion (12b), and a rounded radiusing portion (12c) between the seat portion (12a) and the backrest portion (12b), and wherein extending between said supporting sectional elements (12) is a material basically in the form of a sheet (42, 62) forming a seat (42a, 62a) and a backrest (42b, 62b), said chair beingcharacterized in that each of said ribbed supporting sectional elements (12) is provided with a plurality of through notches (48), which are set at a distance from one another in a longitudinal direction and form respective points of localized bending that enable bending of the supporting sectional element (12) in a vertical plane, said notches (48) being distanced from one another by respective stretches (50) substantially rigid to bending in said vertical plane.
The chair according to Claim 1,characterized in that each of said notches (48) has two opposite surfaces (54) that come into contact upon one another to limit the amplitude of the local bending of the sectional element.
The chair according to Claim 1,characterized in that said notches (48) are formed in an integral ribbing (18) that extends in a median vertical plane of the respective supporting sectional element (12).
The chair according to Claim 3,characterized in that said notches (48) are distributed along said seat portions (12a), said backrest portions (12b) and said radiusing portions (12c) of said supporting sectional elements (12).
The chair according to Claim 3,characterized in that said ribbing (18) has a thickness comprised between 2-20 mm and a height comprised between 10-60 mm.
The chair according to Claim 2,characterized in that each of said notches (48) enables a localized bending of the sectional element with a maximum amplitude comprised between 1°-22°.
The chair according to Claim 1,characterized in that said sheet material (42) is constituted by a fabric or by a mesh with side edges (44) anchored in respective external grooves (14) of said supporting sectional elements (12).
The chair according to Claim 1,characterized in that said sheet material (62) consists of injected plastic material integral with said supporting sectional elements (12).
The chair according to Claim 1,characterized in that said supporting sectional elements (12) are joined together by transverse elements (58, 60) formed integrally with said supporting sectional elements (12).
The chair according to Claim 1,characterized in that each of said supporting sectional elements (12) comprises at least one elastic member (56) formed by a bar of elastic metal material inserted in a seat of said supporting sectional element (12).
The chair according to Claim 2,characterized in that said supporting sectional elements (12) with said integral ribbing (18) are made of injection-moulded plastic material.