- 1 -

This invention relates to a support device for the seat of armchairs or the like with automatically controlled inclination.

Armchairs, chairs and the like are known having their seat inclinable longitudinally and/or laterally in response to the loading applied by the seated person. The seat then returns elastically into its correct rest position when the loading ceases.

This inclination occurs generally by the compliance of n elastic member interposed between the seat and the structure by which it rests on the floor, this compliance being of proportional type in the sense that the greater the seat is displaced from its rest position the greater the reaction of the elastic member against it, so that the system is self-limiting at the ends of this inclination.

However, as the weight of the person seated on the armchair varies, the loading he applies to the elastic member also varies, with consequent variation in these end positions. This is an undesirable aspect in that the armchair yields to a lesser degree when used by a light person and to a greater degree when used by a heavy person. The limiting positions attainable by the inclined seat also vary with the weight of the person seated on it.

— r* —

Inclinable armchairs have already been proposed in which the degree of compliance is substantially independent of the weight of the seated person, by the use of inclination systems comprising levers and preload-able springs-, -floweve } these have ntjt proved satisfactory in that on the one hand the lever and pjreloadable spring system is applied to the seat, so governing its form, and on the other hand they allow only forward and rearward but not lateral inclination of the seat.

An object of the invention is to provide an armchair which allows the seat to incline in every direction with a degree of compliance which is independent of the weight of the seated person.

A further object of the invention is to provide an armchair in which the device which allows this controlled inclination is independent of the form of the seat.

A further object of the invention is to provide an armchair in which the device which allows this controlled inclination is of simple construction and is operationally reliable.

A further object of the invention is to provide an armchair with the facility for differentiating the degree of compliance in the two perpendicular directions, in particular

making it greater in the longitudinal direction and lesser in the transverse direction.

A further object of the invention is to provide an armchair in which seat inclination can be temporarily prevented for specific purpose.

All these and further objects which will be apparent from the description given hereinafter are attained according to the invention by a support device for the seat of an armchair or the like with automatically controlled inclination, comprising a seat, a structure for its resting on the floor, and a member interposed between said seat and said structure to allow said seat to incline to said structure, characterised in that said member comprises an element for elastically counteracting the weight of a seated person and arranged to vary the distance between the two, and an elastically flexible element of essentially vertical extension, the active length of which is related to the distance between said seat and said structure.

A preferred embodiment of the presente invention and a modification thereof are described in detail hereinafter with reference to the accompanying drawings, in which: Figure 1 is a vertical schematic section through a device according to the invention in its unloaded state;

- ^<■ + -

Figure 2 is a partial view thereof corresponding to Figure 1 but in its loaded state; Figure 3 is a partial side view thereof; and Figure * is a partial lower plan view thereof. As can be seen from the figures the seat support device according to the invention is interposed between the seat, which in this example is shown as a plate 1 to be applied to the lower surface of the seat, and the column 2 of the structure by which it rests on the floor. Specifically, the column S comprises a conventional pneumatic cylinder which enables the height of the seat above the floor to be adjusted, for example by a gas spring. On the upper emerging end of the rod 3 there is applied a bush upperly comprising a cylindrical axial cavity 5 which faces upwards to face a downwardly facing cylindrical axial cavity

6 of equal diameter provided in a bush 7 fixed to the seat 1.

The rod 3 is internally hollow and is closed upperly by a valve, the stem 8 of which emerges axially upwards and is faced by a ball 9 fixed to the end of a cable 10 extending within a flexible sheath 11 and traversing at one end end a bush IΞ which is elastically urged against the stem 8 by a spring 13 which operates by expansion.

A conventional traction connection at the opposite end

of the cable 10 opposes the elastic reaction of the permanently compressed spring 13 to prevent the ball 9 activating the stem 8.

Between the two facing cavities 5 and 6 of the bushes ■■+ and 7 there is provided a coil spring 1 which operates by compression, its purpose being to elastically oppose the weight of a person seated on the seat 1, as will be apparent hereinafter .

The outer surface of the bush is cylindrical and on it there can slide a bush 15, which encounters an upper end-of- travel stop in the form of a circumferential step 16 provided at the upper end of the bush 4*.

Between the bushes 7 and 15 there is externally applied a further coil spring 17 having its turns in mutual contact and its ends resting against two steps 18 and 19 provided at those ends of said bushes 7 and 15 which are at the greatest distance apart.

The coil spring 17 is of circular section and is externally surrounded by a sleeve SO which is lowerly cylindrical and upperly frusto-conical with its flare facing upwards. It adheres by means of its lower cylindrical portion to the lower portion of the outer coil spring 17 but is upperly spaced apart therefrom, and is provided with a

circumferential ledge against which the lower edge of the bush 15 rests.

The sleeve ΞO is provided upperly, in correspondence with its free upper edge, with a pair of lateral slots ΞΞ consisting of a vertical portion and a horizontal portion symmetrical about the sleeve axis. These two slots are traversed by a lever S3 pivoted to the plate 1 about the axis of the bush 7 and extending parallel to the plate 1 in the form of a handgrip Ξ4.

The operation of this first embodiment of the device is as followss the height of the seat is adjusted in the conventional manner by the person using it, by slackening the traction on the cable 10 to enable the spring 13 to urge the ball 9 against the stem 8 and thus connect the interior of the column Ξ to the outside.

Having made this preliminary adjustment once and for all, which results in a greater or lesser portion of the rod

3 emerging from the column Ξ, when a person sits on the seat l he compresses the spring 1 to shorten it by an amount which is greater the greater the weight of the person.

As the elastic contraction of the compressed spring 1 causes the bush 7 to approach the bush 4, the

incompressibi li y of the spring 17, upperly secured to the bush 7, and the consequent approach between the two bushes causes the bush 15, to which the spring 17 is lowerly secured, to slide along the bush 4 and thus reduce the free portion of the spring 17 between the two bushes 7 and 4.

This free portion, which has the length 1 in Figures 1 and Ξ, represents the active portion which can undergo flexure following loading applied to the seat with which the plate 1 is rigid, to thus enable said seat to incline in accordance with the loading received.

As the elastic reaction of the spring 17 is greater the smaller the free portion of length 1, and this free portion is shorter the greater the weight of the person seated on the seat 1, it is apparent that the reaction by which the spring 17 reacts against the flexural stresses received via the seat 1 is greater the greater the weight of the person concerned.

By properly sizing the various components the flexural compliance of the seat can adapt with good accuracy to the weight of the person. The sleeve Ξ0, and specifically its upper flared portion, can be used as a limit stop for the bending of the spring 17 and thus for the seat inclination.

Inclination of the seat 1 produces corresponding

inclination of the lever S3 to the sleeve SO, which always remains coaxial to the column Ξ. Thus if the lever Ξ3 is positioned to traverse the vertical parts of the two slots ΞΞ, the seat 1 can incline in all directions. If however the lever Ξ3 is rotated so that it traverses the horizontal parts of the slots ΞO (see dashed lines in Figure 4), the seat 1 cannot incline in any direction.

In a different embodiment not shown on the drawings, the spring 17 is of elliptical instead of circular cross-section, with its major axis in the longitudinal direction. By this means, the seat 1 has greater compliance in the longitudinal direction than in the transverse direction. Again, the desired degree of compliance in the two perpendicular directions can be obtained by suitably sizing said spring 17. In this case the sleeve SO is also of elliptical cross- section, and as in the previous case can act as a limit stop for the inclination of the seat 1.

From the aforegoing it is apparent that the control device of the invention has considerable advantages, and in particular:

- it enables an armchair to be obtained which is inclinable in all directions with automatic control of this inclination in accordance with the weight of the person

using i ; it is of very simple construction and reliable operation; it enables the armchair to be made rigid, thus preventing any seat inclination; it can be applied to armchairs of any seat shape without influencing this shape in any way; it is totally invisible from the outside; it enables the extent of longitudinal and transverse compliance to be differentiated.