The present invention relates to an adjustment device for a chair that has a rocking mechanism.

Nowadays it is known to provide chairs that are fitted with a mechanism the function of which is to enable for example the height adjustment of a seat and the adjustment of the rocking, or the locking in place, of a backrest.

An example of the mentioned prior art is disclosed in US6120096, where the activation of the mechanisms which interact with the seat and with the backrest are activated by way of using a first lever, the rotation of which leads to the packing or otherwise of special slats, and also a second lever, the lifting of which leads to its terminal end interacting with a gas- filled piston present on a central gas-operated post.

Such rocking mechanisms are structurally complex and require a certain force of the user in order to activate the packing of the slats, which may also be subject to possible seizing.

EP 2554075B1 is also known, which relates to a chair with a rocking mechanism,

- wherein the rocking mechanism has a fixed base support with a conical receptacle, said fixed base support being placeable by means of the conical receptacle on a chair pillar of the chair,

- wherein the base support is connected pivotably to a mechanism upper part, which forms a housing at least partially enclosing the base support,

- wherein the pivot axis of the mechanism upper part, which pivot axis runs transversely with respect to the chair longitudinal direction, is arranged next to the conical receptacle, as seen in the chair longitudinal direction,

- wherein at least one spring element interacting on the one hand with the mechanism upper part and on the other hand with the base support is provided in order to return the mechanism upper part from a pivoted position into a starting position, and

- wherein the rocking mechanism is fastened by means of the mechanism upper part to a seat, a seat support or a frame of the chair, or the rocking mechanism is integrated into the seat, the seat support or the frame of the chair, in such a manner that the mechanism upper part is formed by part of the seat, of the seat support or of the chair frame,

characterized in that a valve pin for triggering a pneumatic spring placed in the interior of the chair pillar is located in the region of the conical receptacle, and, in order to trigger the pneumatic spring, a pivot lever interacting with at least part of the rocking mechanism is provided for actuating the valve pin,

and in that the pivot lever is placed in such a manner that the axis of rotation of the pivot lever coincides with the pivot axis of the mechanism upper part.

This solution also has drawbacks: the fact that the rotation axis of the rocking lever is identical to the orientable axis of the upper part of the mechanism entails a compaction of the positioning of the components which compromises the achievement of an optimal rocking and of the optimal activation of the gas-filled post, given that the rocking lever, in order to actuate the pin of the valve of the pneumatic or gas-filled shock absorber, must interact with at least a part of the rocking mechanism.

Furthermore, in such solution, to adjust the height of the seat, it is necessary to activate the pivot lever which has to interact with a sleeve which is provided with a radial release tab which in turn activates the valve pin of the gas-filled post, while to block or release the rocking function of the seat it is necessary to activate a different lever, the lever, which has to interact with the elastic transmission element, which in turn interacts with the locking device.

The presence of two separate levers and of such intermediate elements entails the following drawbacks: complexity of structure, design and assembly, additional costs for providing the adjustment device, and the difficulty of releasing the locking mechanism, in the event of its becoming jammed, because the elastic transmission element dissipates the force imparted to the lever.

Furthermore, in such solution movements can be imparted to the locking device on both a vertical plane and on an oblique plane, making it rather unreliable owing to possible sticking or malfunction.

The aim of the present invention is to solve the above mentioned technical problems, eliminating the drawbacks in the cited known art, by providing a device that makes it possible to achieve at the same time, rapidly, simply and optimally, both the activation and prevention of rocking for a chair, and also the activation of the raising of said chair.

Within this aim, an object of the invention is to provide a device that, in addition to the foregoing characteristics, is also structurally simple and free from sticking.

Another object of the present invention is to provide a device that is low cost and which can be made with the usual conventional systems.

This aim and these and other objects which will become better apparent hereinafter are achieved by an adjustment device for a chair which comprises a rocking mechanism composed of a first plate, which is fixed to a central gas-operated post for the height adjustment of a seat and to which a second plate is articulated, about a first axis that is transverse thereto and so that it can rock, said second plate being fixed to a seat and interacting with means which are adapted to contrast the rocking of a backrest, characterized in that a lever is articulated laterally to said first plate, at an axis that is different from said first axis, and is adapted selectively either to activate, by way of a vertical movement, the height adjustment of said seat or, by way of a horizontal movement, to allow or prevent the rocking of said second plate.

Further characteristics and advantages of the invention will become better apparent from the detailed description of a particular but not exclusive embodiment thereof, illustrated by way of non-limiting example in the accompanying drawings, wherein:

Figure 1 is a perspective view from below of the device applied to a central gas-operated post;

Figure 2 shows the device without the plate associated with a seat;

Figure 3 is a different view of the device in the previous figure, shown in the rocking-prevented condition;

Figure 4 is a view from above of the device in the previous figure in the condition of activation of the central gas-operated post and with the second plate able to rock freely;

Figure 5 is a cross- sectional view of the device taken along the line V- V of Figure 4;

Figure 6 is a cross-sectional view of the device taken along the line VI-VI of Figure 4;

Figure 7 is a side view of the device in the previous figure, without the second plate;

Figure 8 is a view similar to that in Figure 4 of the device in the condition of non-activation of the central gas-operated post;

Figure 9 is a cross-sectional view of the device taken along the line

IX-IX of Figure 8;

Figure 10 is a side view of the device in the previous figure, without the second plate;

Figure 11 is a view from above of the device of Figure 4 in the condition of activation of the central gas-operated post and with the second plate prevented from rocking;

Figure 12 is a cross-sectional view of the device taken along the line XII-XII of Figure 4 in the condition in which the second plate has performed a rocking cycle; Figure 13 is a side view of the device of Figure 11 ;

Figure 14 is a perspective view of the mechanism that allows or prevents the rocking of the second plate;

Figure 15 is a cross-sectional view of the device taken along the line XV-XV of Figure 11 in the condition in which the second plate is prevented from rocking;

Figure 16 shows the first plate without some components inserted.

In the exemplary embodiments that follow, individual characteristics, given in relation to specific examples, may actually be interchanged with other different characteristics that exist in other exemplary embodiments.

Moreover, it should be noted that anything found to be already known during the patenting process is understood not to be claimed and to be the subject of a disclaimer.

With reference to the figures, the reference numeral 1 generally designates an adjustment device for a chair (not shown) which comprises a rocking mechanism composed of a first plate 2, which has a substantially C- shaped box-like shape so as to define a base 3 and two first lateral wings 4a, 4b; in the inner part of the base 3 there is a protruding bushing 5 at which the end of the stem 6 of a central gas-operated post 7, mounted on a footing and used for the height adjustment of a seat (not shown), is associated.

A second plate 10, which can be fixed to a seat (not shown), is articulated to the first plate 2 so that it can rock, by virtue of first pivots 8 a, 8b which lie on a first axis 9 which is transverse and eccentric with respect to the first plate 2.

The first plate 2 interacts with means adapted to contrast the rocking of the seat, such means being constituted by a pair of first springs 11a, l ib which protrude inside the base 3 and are interposed between the latter and the second plate 10.

Preferably at the lateral wing 4a there is an opening 12 at which a lever 13 can be positioned. The opening 12 has dimensions that are such as to allow the lever 13 to perform movements both on a first plane 100, which is perpendicular to the base 3 of the plate 2, and on a second plane 200, which is substantially parallel to the plane of the base 3.

The lever 13 has a first portion 14, which is external to the plate 2, and a second portion 15, which is internal to the plate.

The lever 13 when inactive lies on a different axis with respect to the first axis 9.

The second portion 15 has, adjacent to the opening 12, a cylindrical insert 16 which acts as a seat for a first pivot 17 for pivoting the lever 12 to the first plate 2; the first pivot 17 has a first stem 18 which can be positioned at an adapted first seat 19, which is provided inside the base 3 of the first plate 2.

The first stem 18 acts in the first seat 19 with the interposition of an elastomer or of an elastically deformable element 43, substantially cylindrical and axially perforated, the function of which is to be deformed in the step of inclination of the lever 13 in order to activate the central gas- operated post 7.

Alternatively, the first seat 19 coincides with the hole provided axially with respect to the elastically deformable element 43.

In this case the elastomer or the elastically deformable element 43 can simply be placed in contact with the first plate 2 and accommodate the first stem 18 of the first pivot 17, without an actual seat being provided on the first plate 2.

A movement of the lever 13 on the first plane 100, which is perpendicular to the first plate 2, corresponds to a free movement of the insert 16 at the first pivot 17, the insert 16 having a larger diameter than that of the first pivot 17.

Radially with respect to the insert 16 there is a tab 20, facing in the direction of the lateral wing 4b, from the terminal end of which a second pivot 21 protrudes in the direction of the base 3.

An expansion 22 protrudes below the tab 20 in the interspace between the first stem 18 and the second pivot 21 and has dimensions that are such as to position itself above the central gas-operated post 7 so as to be able to activate it upon a movement that can be imparted to the first portion 14 of the lever 13 on the first plane 100 substantially at right angles to the base 3 and in the opposite direction with respect to the base 3.

This movement makes it possible to perform the height adjustment of the seat.

The vertical movement of the lever 13 with respect to the first plate 2 is freely allowed.

The second pivot 21 of the lever 13 interacts with means that are adapted to prevent the rocking of the second plate 10 with respect to the first plate 2.

Such means are constituted by a mechanism 23, arranged inside the first plate 2, which is constituted by a slider that has a substantially S- shaped plan configuration so as to define a first arm 24, parallelepiped- shaped, which is accommodated in a first cavity 25, which is provided inside the first plate 2 at a side thereof that is opposite the side where the lever 13 enters, with the possibility to slide axially with respect to the first cavity 25 in contrast with an optional second spring.

The second pivot 21 is accommodated in an adapted second cavity 50 which is provided at right angles to the first arm 24.

A bridge 26 is connected to the upper end of the first arm 24 and is arranged along an axis that is inclined with respect to the longitudinal axis of the first plate 2; a second arm 27 is connected in a lower region to the terminal end of the bridge 26, which lies substantially at the longitudinal central axis of the first plate 2, the second arm being parallelepiped-shaped, having a substantially T-shaped plan configuration, and being accommodated inside a second cavity 28 which is provided in the rear region of the first plate 2 where the first springs 11a, 1 lb also are arranged.

The second arm 27, which slides freely and axially with respect to the second cavity 28 along an axis that is longitudinal to the first plate 2, has a first stem 29, with a rectangular plan shape, which is arranged in the interspace between the first springs 11a, l ib, and the upper surface 30 of which is arranged on a plane that lies lower than the plane of arrangement of the bridge 26.

The second arm 27 slides between the pair of first springs 11a, l ib, between which a crossmember 31 is arranged transversely thereto, the second arm 27 sliding below this crossmember.

A first head 32 is connected to the first stem 29 and has a rectangular plan shape, the second wings 33a, 33b of which protrude laterally and transversely with respect to the first stem 29.

There are means adapted to determine the position that can be assumed by the second arm 27 with respect to the crossmember 31, such means being constituted by a ball 34 which works in contrast with a third spring 35 which is provided in a first seat 36 which is provided at right angles to the upper surface 30 of the bridge 26 proximate to the first head 32.

The ball 34 is temporarily accommodatable in one of two separate and adjacent second seats 37a, 37b, which are hemispherical and are provided on the lower surface of the crossmember 31 along a longitudinal axis.

Pushing the lever 13 toward the crossmember 31 causes the retraction of the first head 32 of the mechanism 23 so as to produce an empty space 38 between the terminal end of the first head 32 and the back wall 39 of the second cavity 28, which constitutes a temporary seat for a tooth 40 which protrudes internally and downward with respect to the second plate 10.

This condition corresponds to the ball 34 being positioned in the second seat 37a, which is directed toward the bridge 26, and the mechanism 23 being temporarily locked in the retracted position; therefore the second plate 10 is able to rock with respect to the first plate 2.

A guide for the sliding of the first stem 29 and the first head 32 is provided by the presence of a longitudinal ridge 41 which protrudes from the bottom of the second cavity 28 and is accommodated inside a complementarily-shaped third seat 42 which is provided below the first stem 29 and optionally also below the first head 32.

Pushing the lever 13 away from the crossmember 31 causes the advancement of the first head 32 of the mechanism 23 which in this manner fills the empty space 38 between the terminal end of the first head 32 and the back wall 39 of the second cavity 28 and acts as an abutment for the overlying tooth 40 which protrudes internally and downward with respect to the second plate 10.

This condition corresponds to the ball 34 being positioned in the second seat 37b, which is directed away from the bridge 26, and the mechanism 23 being temporarily locked in the advanced position; therefore the second plate 10 is not able to rock with respect to the first plate 2.

Thus it has been found that the invention fully achieves the intended aim and objects, an adjustment device for a chair that has a rocking mechanism having been obtained that makes it possible to achieve at the same time, rapidly, simply and optimally, and by means of the direct action of a single lever 13, both the activation and the prevention of rocking for a chair, and also the activation of the raising of said chair.

Furthermore the device is structurally simple and free from sticking.

Naturally the materials used as well as the dimensions of the individual components of the device according to the invention may be more relevant according to specific requirements.

The characteristics indicated above as advantageous, convenient or the like, may also be missing or be substituted by equivalent characteristics.

The disclosures in Italian Patent Application No. 102017000057361 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.