EP1639919A1

EP1639919A1 - Device for adjusting and stabilising the inclination of the backrest of a chair

Info

Publication number: EP1639919A1
Application number: EP05425674A
Authority: EP
Inventors: Aldo IVARS S.p.A. Ebenestelli
Original assignee: Ivars SpA
Current assignee: Ivars SpA
Priority date: 2004-09-27
Filing date: 2005-09-27
Publication date: 2006-03-29
Also published as: ITBS20040046U1

Abstract

The invention discloses a device for adjusting and stabilising the inclination of the backrest with respect to the seat of a chair and the like, where the seat is fixed on a plate (11) and the backrest is connected to at least one support (12) pivoted, by means of an arm (13), to the plate holding the seat. The device comprises toothed means (17,18) positioned between the plate (11) of the seat and the arm (13) of the backrest support interlocking to stabilise the inclination of the backrest. A first toothed means (17) is fixed, whereas a second toothed means (18) is moveable with respect to the first toothed means (17) to disengage and allow the inclination of the backrest to be changed.

Description

Field of the Invention

This inventions concerns chairs, in particular office chairs with a variable inclining backrest with respect to the seat, and refers specifically to a device for adjusting and stabilising the inclination of the backrest of such seats..

Prior art

In the type of chair taken into consideration, the seat is usually fixed onto a plate placed on a supporting base and the backrest is applied to at least one support with respect the inclination of which may be varied with respect to a vertical position. For this reason the backrest support is pivoted, by means of an arm, to the plate supporting the seat with the possibility of adjusting its inclination contrasted by a return spring and with the help of a blocking system. A blocking system is known which consists moreover in a friction means, which is associated with the plate of the seat and with the arm of the backrest support and which is loosened to vary the inclination of the backrest and then tightened through a manual control. The blocking and unblocking operations of the friction means are however rather awkward and, if not fully blocked, the friction can also allow unwanted variations in the inclination of the backrest.

Object and Summary of the Invention

The objective of this invention is to provide instead an adjusting device for use in the above mentioned field, which eliminates the friction means and which is much easier to manufacture, easier and smoother to operate and more efficient and reliable.
This objective is achieved, in compliance with the invention, with a device for adjusting and stabilising the inclination of the backrest of a chair or the like, comprising toothed means positioned between the seat plate and the arm of the backrest, and means that interlock to stabilise the inclination of the backrest and one of which is movable with respect to the other to disengage them so as to allow a variation in the inclination of the backrest.

Brief Description of the Drawings

The invention will however be illustrated and become more evident from the following description made in reference to the enclosed indicative and not limiting drawings, in which:

Fig. 1 shows a side view of the plate of the seat and the arm of the support of the backrest in a blocked position; and
Fig. 2 shows a cross section according to arrows A-A in Fig. 1.

Detailed Description of the Invention

In said drawings, 11 represents a plate destined to support the seat and 12 the support destined to support the backrest of a seat.
The plate 11 can be fixed on a supporting base, not shown, whereas the support 12 is associated with an arm 13 by means of which it is pivoted to the plate 11 by a transversal pin 14. In this way, the support 12, together with the backrest, can be inclined with respect to the vertical and with respect to plate 11 that supports the seat. Such an inclination is usually contrasted by an opportunely positioned spring 15 and can be stabilised at different angles by means of a stop device globally indicated by 16.
According to the invention, this device 16 comprises at least one toothed sector 17 integral with or fixed to the plate 11, and a block 18, also toothed, associated with the arm 13 of the support 12. The toothing of the toothed sector 17 and toothed block 18 are ordered on a vertical plane and facing each other so as to interlock. Preferably and for reasons of symmetry in the distribution of the forces, the plate 11 can be equipped with two toothed sectors 17 at a distance in parallel with each other, and the block 18 is provided with two corresponding toothed parts 18 as shown in the drawings.
Whilst the plate 11 of the seat remains fixed to the relative toothed sector or sectors 17, the toothed block 18 on the other hand is associated with the arm 13 of the support 12 and is movable, sliding on guides 19 and manually movable by means of a rod 20 between an active and inactive position according to arrow F in Fig. 2. The movements of the block from one position to the other are in a crossways direction to the plane housing the toothed sectors 17, 18 and can be limited by end of stroke devices 21, 22, respectively.
In the active position, as shown in the drawings, the toothed sector or sectors of said block 18 are lined up with and engage the toothed sector or sectors 17 of plate 11. ln this condition the toothed sectors 17 and 18 are locked, preventing rotation of the arm 13 in respect to plate 1, thus stabilising the position of the support, consequently of the backrest, with respect to the seat.
In the inactive position, the toothed sector or sectors of the toothed block 18 are positioned laterally to, and disengaged from, the toothed sector or sectors of 17 so that the backrest support is free to oscillate so as to change the inclination. Once the required angle has been reached, the block 18 is moved backwards into the active position, causing the opposed toothed sectors 17, 18 to engage in the new position to stabilise the angle chosen. The backward movement of block 18 can be carried out manually using rod 20 or helped by a return spring - not shown.
To be noted that the inactive position, in which the toothed sectors and toothed block 17 are disengaged, may be voluntary and achieved only applying a force against the backrest from the front towards the rear of the backrest, thus avoiding the latter as urged by the spring 15 may rebound and knock the back of the sitting person.
In the drawings and in the description above, the toothed sectors and the toothed block forming the device of adjusting and blocking the inclination of the backrest with respect to the seat have been envisaged in the rear part of the seat plate, between the latter and the arm of the backrest support. This does not mean that they cannot be positioned differently and by this not fall within the ambit of the invention.

Claims

Device for adjusting and stabilising the inclination of the backrest with respect to the seat of a chair and the like, where the seat is fixed on a plate (11) placed on a supporting base and the backrest is fixed to at least one support (12) pivoted, by means of an arm (13), to the seat holding plate with the possibility of changing its inclination with respect to a vertical position under the contrast of a return spring, characterised by comprising toothed means (17, 18) positioned between said plate (11) of the seat and said arm (13) of the backrest support, said toothed means interlocking to stabilise the inclination of the backrest, a first toothed means being fixed, whereas a second toothed means is movable with respect to the first toothed means to disengage them and allow variations in the inclination of the backrest.
Device according to claim 1, characterised by the fact that a first toothed means (17) comprises at least on toothed sector (17) associated with or an integral part of the seat holding plate, and a second toothed means comprises a block (18) associated with the arm (13) of the backrest support and having toothing facing towards that of the first toothed means so as to engage with the latter, the toothed sections of the first and second toothed means being ordered on the vertical inclination adjustment plane of the backrest.
Device according to clams 1 and 2, characterised by the fact that the second toothed means comprising said block (18) is movable on a transversal guide (19) between an active position in which the toothed sectors of the two toothed means interlock to fix the position of the backrest, and an inactive position in which the toothing of the two toothed means are disengaged to allow a variation in the inclination of the backrest.
Device according to the previous claims, characterised by the fact that each toothed means comprises a single or double line of teeth at a distance in parallel with each other.
Device according to the previous claims, characterised by the fact that said second toothed means comprising said block (18) is movable between said active and idle positions by means of a rod (20) connected to them and that said active and inactive positions are set by end of stroke means (21, 22).
Device according to claim 5, characterised in that a spring is associated with the second movable toothed means comprising said block (18) to facilitate return to the active position.