JPS6045306A - Chair - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a chair of the type with a fixed structure and a back and seat part movable with respect to this fixed structure.

(Prior Art) Chairs of the above type (e.g. U.S. Pat. No. 4.084.8)
(see No. 50), the backrest should be such that the person seated on the chair obtains maximum possible comfort in both positions, whether in the upright working position or the inclined resting position. It can be moved from an upright position to a tilted rear position.

Chairs are already known in which, when the backrest moves into its rearwardly inclined position, the seat also tilts backwards so as to prevent the person seated on the chair from sliding forward. (See U.S. Pat. No. 4.o 84.850 mentioned above). In this known device, however, the front edge of the seat part moves perceptibly upwards during the above-mentioned tilting movement and presses the legs of the person seated on the chair from below at knee level; Therefore, it is inevitable to achieve the optimum position from the point of view of comfort.

According to the experimental studies carried out by the applicant, furthermore, in order to achieve the correct posture and optimal comfort of the body of the person seated on the chair during the backward tilting movement of the backrest part: The backrest part pivots around a pivot axis located substantially at the level of the seat part and displaced forwardly with respect to the rear edge of this seat part, which pivot axis rotates the seat of the person seated on the chair. It has been found necessary to substantially coincide with the joint axis between the thigh and pelvis.

Finally, again with a view to achieving the maximum possible comfort, it is necessary for the seat of the chair to tilt back at a smaller angle than the backrest.

OBJECT OF THE INVENTION The object of the invention is to provide a chair of the type mentioned at the beginning of this description, which on the one hand satisfies all the above-mentioned requirements and which, on the other hand, has a relatively simple and economical construction. give.

(Structure of the Invention) To achieve the above object, the present invention provides a chair having a fixed structure and a backrest portion and a seat portion movable with respect to the fixed structure. I' is pivotally connected to the fixed structure about a first transverse axis and is set such that said first transverse axis is located substantially at the level of the seat and is displaced forwardly with respect to the rear edge of the seat. and a backrest support member that regulates the rotation of the backrest support member with respect to the fixed structure of the seat part, and that controls the rotational movement of the backrest support member with respect to the fixed structure of the seat part, and the front rotation end position corresponding to the upright position of the backrest part and the inclination of the backrest part with respect to the seat part support member. a stop means for defining a rearward pivot end position corresponding to the position; a resilient biasing means for biasing the backrest support member towards its forward pivot end position; , pivoted to the fixed structure about a second transverse axis parallel to the first transverse axis and displaced forwardly with respect to the first transverse axis, and substantially corresponding to the rear edge of the seat; A seat support member further connected to the backrest support member.

The particular dynamic connection mentioned above between the fixed structure of the chair, the seat support member and the backrest support provides a number of advantages, including: Firstly, when the backrest is tilted backwards, it is placed essentially at the level of the seat, so as to ensure the correct posture and maximum comfort of the body of the person seated on the chair. and rotates about a pivot axis that is displaced forwardly with respect to the rear edge of the seat. Second, when the backrest moves to its tilted position, the seat also tilts back to reduce or dampen the tendency of the person seated on the chair to slide forward. The angle of inclination is smaller than the angle of inclination of the backrest part, which in this case also ensures maximum comfort. Finally, when the seat is tilted backwards, the seat pivots about an axis located near its front edge, which is caused by excessive elevation of the front edge of the seat. Avoid.

More preferably, in the chair according to the present invention, the fixing structure further includes a transverse member and two support bars projecting forward in a cantilevered manner from two ends of the transverse member, A member is provided with two substantially L-shaped support arms, each coupled at one end to a respective side of the backrest portion and at the other end about the transverse axis at each end of the transverse member. the seat support member comprises two side support members connected to the two sides of the seat, the support arm having two front ends of the support rod attached to the second side support member; characterized in that they have their front ends pivoted about the axis I) and their rear ends connected rearwardly to two above-mentioned cross-shaped support arms of said first transverse axis; There is.

BRIEF DESCRIPTION OF THE DRAWINGS The features and advantages of the pond of the invention will become apparent from the following description, which is given by way of non-limiting example only and with reference to the accompanying drawings, in which: FIG.

FIG. 1 shows a chair comprising a backrest part 3 and a seat part 4 which are movable with respect to a fixed base structure 2.

In the illustrated embodiment, the fixed base structure 2 includes two pairs of side legs 5, each pair being formed by folding a cylindrical element into the shape of are arranged with the apex facing upward. It will be clear, however, that this particular shape of the base structure is shown by way of example only in the accompanying drawings. Any other type of base structure may be substituted, for example a pedestal with a single central column or equivalent.

Further, as shown in more detail in FIGS. 2 and 3, the fixed base structure 2 is cantilevered forward from the end of the transverse member 7 connecting the two pairs of side legs 5. It includes two protruding support rods 6.

(In the case of a base structure consisting of a pedestal with a single central column, the cross member 7 is connected at its center to the upper end of said central column.) Detailed Description of the Invention and Claims In the range
The terms "forward" and "front" refer to the direction indicated by arrow A in FIG. 1, ie, the direction toward which the person seated in the chair faces.

The terms "posteriorly" and "behind" mean the opposite direction. Furthermore, the terms "lateral" and "laterally" refer here to a direction perpendicular to the vertical plane of the chair.

The backrest part 3 is supported by a backrest support member consisting of two substantially L-shaped support arms 8,
Each of them is connected at its upper end to a respective side of the backrest part 3b. On the other hand, the front end of each support arm 8 is pivoted about the transverse axis 9 of the fixed structure 2 of the chair.

The above-mentioned chair has support arms 8 corresponding to the most upright position of the backrest 3; 1) about the transverse axis 9 so that it can be moved to the rearmost rotated position (as shown in FIG. 3) corresponding to the position 1).
A stop means (described in detail below) is provided to restrict the rotation of the support arm 8.

Elastic means are also provided for biasing the support arms 8 of the backrest part 3 towards their forwardmost position (see FIGS. 1 and 2). There is.

The seat 4 is supported by a seat support member consisting of two side support members 10 connected to each side thereof. 2
The two side support members 10 have their front ends pivoted about a transverse axis 11 to the two front ends of the fixed support rod 6. The horizontal shaft 11 is arranged close to the front edge of the seat 4.

The rear ends of the two side support members 10 are pivotally connected to the two lance-shaped support arms 8 substantially in the vicinity of their ribs. As will become clear later, the connection of the rear end of the side support member 10 to the support arm 8 is accomplished by engaging a pin in a slot to allow correct movement of the above-mentioned elements.

2 and 3, when a person sitting on a chair or his back presses on the backrest part 3, this backrest part 3 resists the action of the elastic means which tend to hold it in an upright position. It moves to a tilted position backwards (see Figure 3). When the support arm 8 moves, the side support member 1 opposite to the support arm 81
The pivot zone of 0 moves downwardly, including the rearward slope of the seat 4.

As is clear from the above description and the accompanying drawings, the pivot shaft 9 of the support member of the backrest part to the fixed structure of the chair is displaced forwardly with respect to the rear edge of the seat part 4, thereby causing the backrest part 3 to move backwardly. To enable a person sitting on a chair to take an appropriate posture when the chair is tilted to a resting position. At the same time, the above-mentioned special movable connection joining the support member of the backrest part, the support member of the seat part and the fastening structure of the dowel causes a rearward tilting of the seat part, which causes the backrest part to To prevent the body of the person sitting on the chair from sliding forward when the chair tilts backward, the inclination of the seat part 4 is, however, smaller than the inclination of the backrest part 3 (1). Furthermore, the seat 4 is pivotally connected to the fixed structure of the seat substantially close to its front edge, so that when said seat is tilted rearward, it moves in three directions. , this gives maximum comfort to the person sitting in the chair.

According to the present invention shown in FIGS. 4 to 19 (5)
The various embodiments of the child differ from each other primarily in the realization of elastic means for biasing the backrest part 3 into its upright position.

In FIGS. 4 to 7, the cross section 7 consists of a hollow element having a vertical lug 12 at each of its ends.

As shown in FIG. 6, each vertical lug 12 is penetrated by a cylindrical pivot pin N3 attached to the vertical lug 12. As shown in FIG. That portion of the cylindrical pivot pin 13 that projects outwardly from the vertical lug 12 of the cross member 7 is fillet 1
This fillet 15 is fitted into the hole 14 of 5, and this fillet 15 has a substantially triangular shape, and the fillet 15 has a \7-shaped cylindrical element constituting two corresponding side legs 5, and a It is welded. The above fillet 15 is further added to the vertical lug] 2.
A protrusion 16 that engages with the hole 17 is attached. The fillet 15 is removably fixed to the pin 13 by a screw 18 which is screwed into a screw hole formed at the outer end of the cylindrical pivot pin 13.

One annular member is located between the head of the screw 18 and the fillet 15 [
This will be provided.

Each support bar 6 has a box section including two side walls 20 and one top wall 21. The outwardly facing side wall 20 of the chair 20 is connected at its rear end (see FIG. 4) to the vertical lug 12 of the cross member 7.

Further, each of the two support arms 8 has two side walls 23 and 1
It has a box section including two top walls 24.

The bushing 25 is interposed between the two side walls 23 of each support arm 8 at the front end of each support arm 8, and is welded to the side walls 23. An auxiliary bush 26 is interposed in the bush 25, and is rotatably attached to a portion of the cylindrical pivot-mounted bush 3 that protrudes from the vertical lug 12 toward the inside of the chair. This auxiliary bushing 26 has an annular run at one end that abuts the vertical lug 12, and the other end abuts a disc 27 fixed to the corresponding end of the cylindrical pivot pin 13 by a screw 28. The two side walls 23 of each support arm 8 each have two holes 29, 30 in which the auxiliary bushing 2G and the disc 27 fit. The bushing 25 has a flat side surface 25a (see FIG. 5).

A horizontal pin 31 is fixed within each support rod 6 in correspondence with the pivot shaft 11 of the seat portion 4 . For more details, please refer to this 1 (4)
One end of the pin 31 is securely clamped by a grub-5crew+) 32 in a 72-shut 33 welded to the inside of the support rod 6 (see FIG. 7). Horizontal pin 31
passes through the hole 34 in the side wall 20 to the opposite side of the bushing 33 and cantilevers toward the interior of the chair to act as a pivot pin for the side support member 10 of the seat. .

In the illustrated embodiment, each side support member 10 (see FIGS. 6 and 7) comprises a hollow element with a corresponding hole in the side wall of the side support member 10. An insertion element 36 with arranged fittings 37a, 37b is fixed by screws 35. The insertion element 36 has a horizontal pin 31 projecting from the support rod 6 in a cantilevered manner at its front end.
It has a hole 38 for the end pivot assembly. The insertion element 36 is locked to the transverse pin 31 by three annular discs which are fixed to the pin 31 by springs 40.

Adjacent to the rear end of each side support member 10, the insert element 36 has a slot 41 within which a transverse pin 4 projects from the support arm 8 towards the interior of the chair.
2 is slidably mounted. Above pin 42
passes through the side wall 23 of the support arm 8 facing the interior of the chair, and the interior of the support arm 8 has an enlarged head 43 welded to said side wall 23. The fourteen element 36 is connected to the transverse pin 421 by a disc 44 which is secured to the free end of the transverse pin 42 by a screw 45.

Disposed within each support rod 6 is a helical spring 46 having one end hooked to the transverse pin 31 and the other end firmly fixed to a body 47 (see FIG. 5) having a threaded shaft hole. has been done. A threaded bolt 48, acting as a connecting rod, is screwed into a tapped hole in the body 47, the head 49 of which is connected to the corresponding support arm 8 in a manner described below. There is. Said bolt 48 is guided in a downwardly open notch 50 formed in the vertical wall forming part of a bracket 51 welded into the fixed support rod 6. .

The head 49 of the threaded port 48 presses against a cylindrical element 52, which has a transverse hole through which the threaded bolt 48 is inserted, and a bar welded to the inside of the support arm 8. Plate element (Hus-set ele+ne
nL) is in contact with the wall portion 53 forming a part of the wall portion 54. This wall portion 53 has a hole 5 through which the screw bolt 48 passes.
5. To accommodate the assembly of the threaded bolts 48, the shroud element 54 has an opening 5 in the internal vertical wall 57.
6.

The assembly of the different parts described above is further facilitated by the fact that the box section elements constituting the support n6 and the support arm 8 are open downwards.

4 and 5, the upper wall 24 of each support arm 8
is a notch 24b that opens downward at the front end of the arm.
Each threaded bolt 48 is engaged within the downwardly inclined portion 24a.

The helical spring 46 constitutes the above-mentioned elastic means for biasing the backrest 3 toward the forward rotation end position of the backrest 3 corresponding to the upright position of the backrest 3. Each spiral spring 46
is adapted to urge the head 49 of each bolt 48 towards a cylindrical element 52 located in the inner wall 53 of each support arm 8.

Therefore, the support arm 8 is urged toward its forward pivot end position, which is located at the front end of the upper wall 24.
a and the two side walls 20 of each support rod 6, 2 in FIG.
Defined by the contact between the two trailing edges, designated 0a.

In step 4, a person sitting on a child presses the backrest part 3 with his back in order to press the backrest part 3 into its backward inclined position.
When pressed, the support arm 8 pivots about a transverse axis 9 about the vertical lugs 12 at both ends of the cross member 7. The center of the cylindrical element 52 thus forms an arc around the transverse axis 9, causing an increase in the distance between the head 4 (J) of the threaded bolt 48 and the transverse pin 31, which causes a corresponding helical deflection. 46 is extended.The rearmost pivoted position of the support arm 8 is defined by the ultimate rest position of the pin 42 in the slot 41.

The bolt 48 is on the flat surface 25a of the hook 25.
Following the pivoting movement of the support arm 8 about the pivot axis 9, which contributes to allowing movement without interfering with the support arm 5,
The pin 42 to which the rear end of the side support member 10 of the seat is connected moves downwardly from imparting rotation of the side support member 10 about the pin 31 supported by the support rod 6.

The embodiment of the chair according to the invention shown in FIGS. to 7th
In contrast to the embodiment shown, each spring 58 is arranged in the front end of a respective support arm 8 and is attached to a pivot pin which is pivotally connected to the vertical lug 12 of the support arm 8 or of the cross member 7. wrapped in a spiral around the Each spring 58 further has one end 59 that presses against the lower surface of the upper wall 24 of each support arm 8 and one end 60 that presses against the inner surface of one of the two vertical walls of the hollow transverse abutment 7. are doing. The screw 61 is screwed into this vertical wall, and the free end of the screw 61 is in contact with the end 60 of the spring 58, so that the spring force of said spring can be adjusted by the screw 61. .

Referring to Figures 10 and 11, the embodiments shown in these Figures show that the resilient biasing means for biasing the backrest towards its upright position are comprised of two helical springs b2=. This differs from the previously described embodiments in that each helical spring 62 is arranged in the enlarged end 7a of the hollow transverse member '7, with its axis horizontal and parallel to the vertical plane of symmetry of the chair. has been done. One end of each spring 62 is in contact with an annular shoulder of a bushing 63 that is threaded into a screw 64.
4 is disposed within the vertical wall 71 of the cross section shrine 7 and is used to adjust the spring force of the spring 62. The opposite end of the spring 62 exerts a spring force against the bottom wall of a fork-like element 65, and the vane of this seven-owl-like element 65 is connected to one end of the lever 67 by a pin 66 (no. 10), this lever 67 is fixed to each support arm 8 and is itself pivoted about a transverse axis 9 to the fixed structure of the chair. In FIG. 11, when the backrest is moved to the rearward tilted position, the lever 67 rotates counterclockwise and the associated helical spring 62 is compressed.

Reference is made to FIGS. 12 to 14, which illustrate the fourth aspect of the invention, which can only be implemented when the fastening structure of the chair comprises two pairs of side legs consisting of cylindrical elements. A child example is shown. In this embodiment, the elastic means for biasing the backrest part into its upright position consist of two helical springs 68, each of which is arranged on a respective side leg 5. The lower end of each helical spring 68 is connected to a body 69 that is slidably mounted within the side leg S and has an axially threaded threaded hole 7o. The side leg 5 and the body 69 are connected to the body 6 within the side leg S.
9 has a non-circular cross section (see FIG. 13) to prevent rotation. The screw 71 that is screwed into the screw hole 70 of the body 69 has a ferrule at its lower end.
? 3, and is screwed and welded to a nut 72 inside this stone protrusion 73.

By adjusting the screw 71, the position of the body 61 within the side leg 5 is adjusted, resulting in a change in the spring force of the helical spring 68. The upper end of the spiral spring 68 is hung on a transverse pin 74, and both ends of the transverse pin 74 are fixed to the two side walls 23 of each support arm 8.

In this embodiment, furthermore, two discs 75 are welded to opposite sides of each inverted V-shaped cylindrical element forming each moon of the side legs 5 at the apex of the square. Two aligned holes 76 are formed in the disk 75, their common axis coinciding with the transverse axis 9. A cylindrical element 77 is welded to the two discs 75, the ends of which are connected to the holes 76.
inserted inside. The cylindrical element 77 pivotally supports a pin 79 with two bushings 78 interposed therebetween.
The two side walls of the support arms 8 of the corresponding backrest parts are fixed. The above pin 79 has a head of 8゜.
o presses against one side wall 23 through an interposed washer s1 and is fixed in position by a disc 82;
is fixed to the opposite end of the pin 79, and is pressed against the north side wall 23 through the entire washer 81. The two disks 75 have throwers 84' (one of which can be seen in FIG. 13) in which transverse pins 74 are slidably mounted and associated. One end of the spiral spring 68 is hanging.

Apparently, the side legs 5 also have an opening through which the pin 74 passes. Each support rod 6 is internally provided with a bracket 6e welded thereto and connected to a bracket 6f welded to the side leg 5. This is used for fixing the support frame 6 to the side legs 5.

Referring to FIGS. 15 to 17, these drawings include:
The elastic means for biasing the backrest into its upright position consists of a torsion bar 84.
An embodiment of the invention is shown which differs from that described above in that the cross member 4 is arranged in the cross member 7 and fixed centrally to said cross member 7.

As shown in FIG. 15, the torsion bar 84 has a U-shaped center portion 85, and this center portion S5 has a screw hole 88.
It is arranged in the notch 86 of the anchor member 87 having a z. The screw 8 is screwed into the screw hole 88 and is housed in the box-shaped portion 90 at the center of the cross member 7. The screw 89 has a shank (
shank) and adjust with the diameter pin 91 7
92. By adjusting the adjustment knob 92, it is possible to change the force of the torsion bar 84.

These parts of the torsion bar 84 branching off from the central part 85 (indicated by reference numeral 93) are connected to the hollow cross member 7 by means of two support members 94 each screwed onto said cross member 7. is rotatably supported at the bottom of the The free end 95 of the torsion bar 84 is however arranged inside each support arm 8 of the backrest part and presses against the inner surface of the wall 24 of the support arm 8.

Referring to FIGS. 18 and 19, these drawings include
The resilient means for biasing the backrest part into an upright position consist of a series of substantially C-shaped leaf springs 96 on each side of the chair, which leaf springs 96 are arranged at their ends to An embodiment is shown in which it presses against two oppositely arranged walls 97,98 which are respectively fixed to the support arm 8 and fixed to the corresponding ends of the cross member 7.

The end of the cross member 7 is further provided with an internal cross pin 99 which engages in a slot 100 formed in the support arm 8.

The chair according to the invention in the various illustrated embodiments includes:
More specifically, it is also designed as a chair for collective use, for example in conference halls or theaters. The chair according to the invention is therefore designed to be able to be combined side by side with a pond chair (of a type known per se) and easily and quickly, as generally occurs in the case of chairs of the type mentioned above. It is obvious that it would be a mistake to provide means for accessing accessories such as armrests or the like to the chair. Moreover, the above-mentioned chairs are also, as is well known per se, shaped like other chairs of the same type (≦j) in order to achieve a minimum size when stacked vertically. can do.

Of course, while the principles of the invention remain the same, constructional details and practical embodiments may vary widely from that described and illustrated by way of example only, without departing from the scope of the invention. Can be changed.

(Effects of the Invention) As is clear from the above detailed description, the present invention is a useful invention that achieves the intended purpose.

[Brief explanation of the drawing]

1 is a perspective view of a first embodiment of a chair according to the invention; FIGS. 2 and 3 are enlarged views showing details of the chair of FIG. 1 in two different positions; and FIG. Enlarged portion 111 showing details of the chair in Figure 1
1 is a perspective view, the 5th section is a sectional view taken along the V-V line in FIG.
A cross-sectional view taken along the line Vl-Vl in the figure, FIG.
, sectional views along the I-Vll line, FIGS. 8 and 9 show modifications of FIGS. 4 and 5 showing the second embodiment of the chair according to the present invention, and FIGS. The figures show a third embodiment of the chair according to the invention, FIGS. 12, 13 and 14 show fourth embodiments of the chair according to the invention, and FIGS. FIG. 17 shows a fifth embodiment of the chair according to the invention, and FIGS. 18 and 19 show a sixth embodiment of the chair according to the invention. 2...Fixed base structure, 3...Backrest portion, 4...
- Seat part, 7... Cross member, 7a... Enlarged end, 8.
...Support arm, 9...Horizontal shaft, 10...Side support member, 11...Horizontal shaft, 13...
Cylindrical pivot pin, 20a...forward rotation end position, 24a...
・・Downward slope part, 41・・thrower)・・・12・・・
Horizontal pin, 46...d4 pivot spring, 48...screw A.
Bolt, 58...Spring, 59.60...End, 62
...Spiral spring, 67...Luv, 68...Spiral bone, 69...Body, 70...Drilling hole, 71...
Screw, 72... Nut, 74... Pin, 84... Torsion bar, 84'... Slot, 8
5... Center, 87... Anchor member, 9G... Leaf spring, 97.98... Wall. Patent Applicant Castelli Società Per Achio 2 Representative Patent Attorney Aoyama Aoyama and 2 others Lr1.13 e-/bi

Claims (11)

[Claims] (1) In a chair having a fixed structure (2) and a backrest (3) and a seat (4) that move relative to the fixed structure, is pivotally connected to the fixed structure (2) about a first transverse axis (9), said first transverse axis (
9) a backrest support member (8) located substantially at the level of the seat (4) and set forwardly displaced with respect to the rear edge of the seat (4); )
The rotation of the backrest support member (8) is restricted, and the backrest supports the front rotational end position corresponding to the upright position of the backrest part (3) and the rear rotational end position corresponding to the inclined position of the backrest part (3). A stopping means (24a. 10g, 42.41) defined for the member (8) and a backrest support member (8) in its forward rotation end position (=1
a second horizontal axis (11) parallel to the first horizontal axis (9) and displaced forwardly and substantially proximate to the leading edge of the fixing structure (2); ), and a seat support member (10) corresponding to the rear edge of the seat (4) and substantially connected to the back support member (8). A characteristic chair. (2) comprising a chair fixing structure (2) or a transverse member (7) and two support bars (6) projecting forward in a cantilevered manner from two ends of the transverse member (7); The backrest support members are each connected at one end to a respective side of the backrest part (3) and at each end of the transverse member (7) around said first transverse axis 1). The end of the pond comprises two substantially L-shaped support arms (8) which are pivotally connected, and the seat support member comprises two side supports connected to two sides of the seat (4). The two side support parts include a support bar (10), and the second side support part is attached to the front end of the support rod (6), respectively.
and a rear end connected to a support arm (8) of the shape described above behind the first transverse axis (9). A chair according to claim 1, characterized in that: (3) Each of the support bars (6) has a box-shaped body, and the elastic biasing means includes at least one helical spring (46) disposed within the box-shaped body of one of the support bars (6). ), and this helical spring (46) is connected to the support rod (
The connecting bolt (4') has one end connected to the front end of the connecting bolt (4') and the other end connected to one end of the connecting bolt (48).
8), the other end of which is connected to the respective backrest support arm (8) in a zone that does not coincide with the first transverse axis (9); Chair. (4) Each support arm (8) of the backrest has a pivot pin (1
3) to each end of the transverse member (7), said resilient biasing means being from a spring (58) helically wound around said pivot pin (13). Become,
This spring (58) has two ends (59°, 60) pressing respectively against the respective ends of the back support arm (8) and the cross member (7). The chair according to claim 2, characterized in that: (5) The transverse member (7) has a box-like body, and the elastic biasing means is arranged at one end (7a) of the transverse member (7).
) at least one spiral runner located within 'ne (62
), this spiral spring (62) is pivoted about one end connected to the transverse member (7) and said first transverse axis (9), and is connected to a support arm (8) of each backrest part.
) has the other end connected to one end of a lever (67) fixed to the helical spring (62 2. The chair according to claim 2, characterized in that it is designed to compress the air. (6) The fixing structure includes two side legs (5) each consisting of a cylindrical element, said elastic biasing means being a helical spring arranged inside one of the side legs of the chair. (68), which helical spring has its lower end connected to the anchor elements (6) arranged in the side legs (5) and its upper end connected to the respective backrest support arm (8). 1ti child according to claim 2, characterized in that it has. (7) means (69 and 72) are provided for adjusting the position of said anchoring element (69) within said side leg (5);
7. The chair according to claim 6, characterized in that: (8) The upper end of the spiral bone (68) constitutes a part of the backrest support arm (8), and the side leg (
6. The chair according to claim 6, characterized in that the chair is hung on a horizontal bin (74) projecting through the guide groove (84') of the side leg inside the chair. (9) The transverse member (7) has a box-like body,"-2
The elastic biasing means are arranged along the transverse member (7).
and a torsion bar (84) centrally fixed to the center of the transverse member (7), the ends of which are attached to the two backrest support arms (8).
Claim 2, characterized in that:
Chairs listed in section. (10) The above-mentioned cross member (7) is a torsion bar (S4)
Means (87) for fixing the center (85) of (l
iii. The measuring means (87) is a torsion bar (8
4) A chair according to claim 9, characterized in that it is adjustable in position to allow adjustment of the force. (11) Each end of the cross member (7) and the corresponding backrest support arm (8) have two oppositely disposed surfaces (
97, 98), and the resilient means for biasing the back towards its upright position consist of at least one substantially C-shaped leaf spring (96), the ends of which The chair according to claim 2, characterized in that faces (97°98) are pressed against each other.