EP1854378A1

EP1854378A1 - Chair with tiltable backrest

Info

Publication number: EP1854378A1
Application number: EP06425324A
Authority: EP
Inventors: Giancarlo Piretti
Original assignee: Pro Cord SpA
Current assignee: Pro Cord SpA
Priority date: 2006-05-12
Filing date: 2006-05-12
Publication date: 2007-11-14
Also published as: JP2007301339A

Abstract

Chair comprising:
- a base structure (12),
- a seat structure (22) fastened to the base structure (12),
- a backrest (32) that is tiltable backwards relative to a rest position under the action of a backwards thrust applied by the user, and
- two elastic devices (40) that support the backrest (32) and tend to return elastically the backrest to the rest position,

Each of said elastic devices comprises:
- case (42),
- an oscillating member (58) articulated to the case (42) by means of a pin (56),
- at least one elastic element (78) which tends to thrust the oscillating member (58) towards a rest position.

The case (42) of each of said elastic devices (40) is configured as a separate element, independent of the base structure (12) and is inserted in a longitudinal seating (30) of the seat structure (22).

Description

The present invention relates to a chair with a backrest that is tiltable backwards under a backwards thrust applied by the user.
The document EP-A-1557115 by the same Applicant describes a chair having the characteristics contained in the preamble of claim 1. In this known solution, the backrest is tiltable backwards relative to a rest position under the action of a backwards thrust applied by the user. The backrest is connected to the base structure of the chair by means of two elastic devices which support the backrest and tend to return the backrest elastically to the rest position. Each of said elastic devices comprises a lever having a first section fastened to the backrest and a second section that co-operates with elastic elements. The second section of the lever is housed in a case that is integrally formed in the base structure of the chair.
Chair manufacturers often need to apply to different chair models the mechanism that enables to obtain the backwards inclination of the backrest. The solution described in EP-A-1557115 requires the base structure of the chair to be shaped specifically to receive the elastic devices that enable the backwards inclination of the backrest. Therefore, to apply to different chair models the mechanism that enables the backwards inclination of the backrest, it is necessary to re-design the base structure of each model.
The object of the present invention is to provide an enhanced chair that enables to obtain the backwards inclination function of the backrest on different chair models, with no need to modify the base structure of the chair.
According to the present invention, said object is achieved by a chair having the characteristics set out in claim 1.
The present invention shall now be described in detail with reference to the accompanying drawings, provided purely by way of non limiting example, in which:

Figure 1 is a perspective view of a chair according to the present invention,
Figure 2 is an enlarged scale perspective view of an elastic device indicated by the arrow II in Figure 1,
Figure 3 is an exploded perspective view of the elastic device of Figure 2,
Figure 4 is a bottom perspective view of the elastic device of Figure 2, and
Figure 5 is a section according to the line V-V of Figure 2, showing the elastic device in the position of maximum backwards inclination.

In Figure 1, the reference 10 designates a chair according to the present invention. The chair 10 comprises a base structure 12 which can be of various types. In the illustrated example, the base structure 12 comprises two lateral supports 14, joined together by two transverse bars 16. Each lateral support 14 is permanently fastened to a front leg 18 and to a rear leg 20. However, the specific form of the base structure 12 is not relevant for the purposes of the present invention. As shall become readily apparent below, the present invention enables to apply the backwards inclination function of a backrest, with elastic return of the backrest in rest position, to chairs with any type of base structure, even if not specifically designed for the implementation of this function.
In Figure 1, the reference number 22 designates a seat structure that is fastened to the base structure 12. A seat padding (not shown) is to be fastened on the seat structure 22. The seat padding can vary according to the chair model, maintaining unchanged the seat structure 12. The seat structure 22 has substantially the shape of a frame, preferably made of injection-moulded plastic material. The seat structure 22 comprises two lateral parts 24 joined by a front part 26 and by a rear part 28. The seat structure 22 is provided with holed bosses for fastening, by means of screws (not shown), the seat structure 22 to the base structure 12 and for fastening (also by means of not shown screws) of the seat padding to the seat structure 22.
The seat structure 22 is provided with two seats 30 which extend longitudinally at the rear lateral parts of the seat structure 22. The two seats 20 have substantially parallelepiped shape and are open on the rear part of the seat structure 22.
Also with reference to Figure 1, the chair 10 comprises a backrest 32, preferably constituted by injection-moulded plastic material. The backrest 32 comprises a bearing part 34 delimited laterally by two vertical portions 36 each of which is provided at its lower end with a seat 38 open inferiorly.
The chair 10 according to the present invention comprises two elastic devices 40 which support the backrest 32 and tend to return the backrest 32 elastically towards a rest position.
With reference to Figure 2 through 5, each elastic device 40 comprises a case 42 preferably constituted by stamped metal plate. The case 42 has a general parallelepiped shape, with two lateral walls 44 that extend orthogonally to an upper part 46. As shown in Figure 4, the lateral walls 44 have at their bottom end respective bent tabs 48 which extend parallel to the upper part 46 and constitute a lower part of the case 42. The upper part 46 is provided with a tab 50 projecting frontally and provided with holes with vertical axis 52. The lateral walls 44 of the case 42 are provided with aligned holes 54 which support an articulation pin 56, positioned in proximity to the rear end of the case 42.
Each elastic device 40 comprises an oscillating member 58 constituted by a substantially L shaped lever. The oscillating member 58 is articulated to the case 42 by means of the pin 56.
The oscillating member 58 comprises a backrest support section 60 and a reaction section 62. In the illustrated example, the two sections 60, 62 are constituted by two distinct elements fastened to each other. This is because, in the embodiment illustrated in the figures the backrest support section 60 is constituted by plastic material, whilst the reaction section 62 is constituted by stamped metal plate. Alternatively, if both sections 60, 62 were made of the same material, it would be possible to obtain the oscillating member 58 in a single piece. The backrest support section 60 has an elongated portion 64 which is inserted in the respective seat 38 of the backrest 32. The reaction section 62 has substantially channel-like shape with a bottom wall 66 and two lateral walls 68. The lateral walls 68 are provided with aligned holes 70 through which extends the articulation pin 56. The pin 56 also extends through a through hole 72 of the backrest support section 60. The reaction section 62 is fastened to the backrest support section 60 by a screw 74. The reaction section 62 is preferably provided with through windows 76 situated in correspondence with the tabs 48 of the case 42.
The elastic device 40 comprises at least one elastic element 78 positioned between the upper part 46 of the case 42 and the bottom wall 66 of the reaction section 62. In the illustrated example, two elastic elements 78 are provided, each of which is constituted by a helical spring in compression having an upper end which bears against the wall 66 of the reaction section 62. The elastic elements 78 tend to maintain the reaction section 62 of the oscillating member 58 bearing against the lower part 48 of the case.
The case 42 is configured as a separate element, independent of the base structure 12 and of the seat structure 22. The case 42 has parallelepiped shape which establishes a shape coupling with the respective seat 30 of the seat structure 22. As shown in Figure 1, the case 42 of each elastic device 40 is inserted in the respective seat 30 through the rear opening of the chair. The elastic devices 40 can be fastened to the seat structure 22 by means of screws 80 which extend through the holes 52 of the front tab 50 of the respective cases 42.
In the assembled position, the backrest 32 is connected to the seat structure 22 by means of the elastic devices 40. The elastic elements 78 tend to maintain the backrest in a rest position. The user can cause a backwards inclination of the backrest 32 applying a backwards thrust on the backrest 32. Said thrust produces a backwards inclination of the two oscillating members 58, against the elastic force of the elastic elements 78. Figure 5 shows one of the two elastic devices 40 in the position of maximum backwards inclination. The position of maximum backwards inclination of the backrest 32 is defined by the condition of contact between the lateral walls 68 of the reaction section 62 against the upper part 46 of the case 42.
The elastic devices 40 are autonomous modular elements, wholly independent with respect to the base structure 12. This allows to apply the backwards inclination function of the backrest 32 to any type of chair, with no need to modify or to design specifically the base structure 12 of the chair. The seat structure 22 of the chair according to the present invention also constitutes a modular element applicable to base structures 12 of different kinds. On the seat structure 22 can be mounted seat paddings with different characteristics according to chair type.
The solution according to the present invention is characterised by a considerable simplicity of assembly and by a reduced number of components. The backrest 32 is mounted to the seat structure simply by inserting the elastic devices 40 into the seats 30 of the seat structure 22 and inserting the elongated portions 64 of the elastic devices 40 in the seats 38 of the backrest 32. The fastening of the backrest 32 to the elastic devices 40 can be completed by means of screws 82 (Figure 1).

Claims

Chair comprising:
- a base structure (12),

- a seat structure (22) fastened to the base structure (12),

- a backrest (32) that is tiltable backwards relative to a rest position under the action of a backwards thrust applied by the user, and

- two elastic devices (40) that support the backrest (32) and tend to return elastically the backrest to the rest position,
in which each of said elastic devices comprises:
- a case (42) having an upper part (46), a lower part (48) and two lateral walls (44),

- an oscillating member (58) articulated to the case (42) through a pin (56) borne by said lateral walls (44), in which the oscillating member (58) has a backrest support section (60) and a reaction section (62),

- at least one elastic element (78) having a first end that bears against the upper part (46) of the case (42) and a second end that bears against said reaction section (62) of the oscillating member (58) and tends to bias the reaction section (62) to abut against the lower part (48) of the case (42),
characterised in that the case (42) of each of said elastic devices (40) is configured as a separate element, independent of the base structure (12) and is inserted in a longitudinal seating (30) of the seat structure (22).
Chair as claimed in claim 1, characterised in that the seat structure (22) comprises two lateral elements (24) provided at their rear ends with respective seats (30), open at the rear, into which are inserted with shape coupling the cases (42) of said elastic devices (40).
Chair as claimed in claim 1, characterised in that the backrest support structure (60) has an elongated portion (64) that is inserted into a respective seating (38) of the backrest (32).
Chair as claimed in claim 1, characterised in that the case (42) has a general parallelepiped shape with the lower part (48) formed by bent tabs of the lateral walls (44).
Chair as claimed in claim 1, characterised in that the backrest support section (60) of each oscillating member (58) is constituted by injection-moulded plastic material.
Chair as claimed in claim 1, characterised in that the backrest support section (62) of each of said oscillating members (58) is constituted by stamped metal plate.
Chair as claimed in claim 1, characterised in that each of said elastic devices (40) comprises two helical springs in compression (78) positioned in parallel to each other between the upper part (46) of the case (42) and a bottom wall (66) of the reaction section (62).