CN218588617U - Waist supporting device, backrest support and seat unit - Google Patents

Abstract

The utility model provides a top waist device, include: a guide rail; the sliding block is slidably mounted on the guide rail; one end of the first connecting plate is hinged to the sliding block, and the other end of the first connecting plate is hinged to the waist ejecting plate; a second link plate having one end hinged to the guide rail and the other end hinged to the top waist plate; and the driving piece is used for driving the sliding block to axially slide along the guide rail so as to enable the top waist plate to be far away from or close to the guide rail. The utility model realizes the position adjustment of the top waist plate relative to the guide rail by matching the first connecting plate and the second connecting plate with the slide block and the guide rail, simplifies the driving structure of the first connecting plate and the second connecting plate by matching the slide block and the slide rail, and leads the device to have compact structure and less occupied space; simultaneously, the motion range of first even board is bigger, and under the same condition of first even board length, this structure can make the top waist board reach bigger adjustment height under the effect of first even board, and accommodation range is big, and the practicality is strong.

Description

Waist supporting device, backrest support and seat unit

Technical Field

The utility model relates to a function sofa technical field especially relates to a top waist device, back support and seat unit.

Background

The waist supporting device is used for the functional sofa, and can support the waist of a user in the using process of the user, so that the functional sofa is more ergonomic, and the comfort and the user experience of the functional sofa are improved.

Chinese patent publication No. CN211559469U discloses a lumbar support device, which includes a top lumbar folding plate for lumbar support; a scissor portion pivotally connected to the top waist flap to move the top waist flap between a fully retracted position and a fully extended position; the fixing part is rotatably connected with the scissor part and fixedly connected with an external structural part; the scissors part comprises a first connecting rod and a second connecting rod which are mutually crossed and are connected in a rotating mode, the top of the second connecting rod is rotatably installed on one end of the top waist folded plate, and a sliding space for the top of the second connecting rod to slide horizontally is formed in one end of the top waist folded plate; the top of the first connecting rod is rotatably arranged at the other end of the top waist folded plate, the tail of the first connecting rod is rotatably arranged at one end of the fixed part and is driven by the driving mechanism to rotate or displace, and the tail of the second connecting rod is rotatably arranged at the other end of the fixed part. The technical scheme simple structure that this patent provided can realize the altitude mixture control of top waist folded plate to be convenient for different users' top waist and use.

However, in the technical scheme that above-mentioned patent provided, adopt and cut fork portion to support and adjust the top waist folded plate, the fork portion of cutting here is rotated by first connecting rod and second connecting rod alternately and is connected and form, and this structure occupation space is big to it is little to adjust the size scope of top waist folded plate, and the practicality is not good enough.

SUMMERY OF THE UTILITY MODEL

To the deficiency of the prior art, an object of the utility model is to provide a top waist device, its structural design is compact, can realize the regulation on a large scale of waist board when occupation space is little.

A second object of the present invention is to provide a backrest support, which is adjustable by the waist-supporting device and the headrest device, so as to enrich the function of the backrest support.

A third object of the present invention is to provide a seat unit, which is adjustable and helps to improve the user's experience.

The embodiment of the utility model discloses a realize through following technical scheme:

a lumbar support device comprising: a guide rail; the sliding block is slidably mounted on the guide rail; one end of the first connecting plate is hinged to the sliding block, and the other end of the first connecting plate is hinged to the waist ejecting plate; a second connecting plate, one end of which is hinged to the guide rail, and the other end of which is hinged to the top waist plate; and the driving piece is used for driving the sliding block to axially slide along the guide rail so as to enable the top waist plate to be far away from or close to the guide rail.

According to a preferred embodiment, the hinge point of the first connecting plate and the top waist plate is a first hinge point; the first connecting plate is provided with limiting bulges which are distributed close to the first hinge point; a first stop block and a second stop block are arranged on the second connecting plate; when the driving piece drives the sliding block to axially slide along the guide rail, the limiting protrusion moves between the first stop block and the second stop block.

According to a preferred embodiment, the second connecting plate is provided with a yielding surface, and the yielding surface is distributed between the first stop block and the second stop block and faces the limiting protrusion.

According to a preferred embodiment, the device further comprises a first fixing plate arranged on the guide rail or the driving part, and the second connecting plate is hinged to the guide rail through the first fixing plate.

According to a preferred embodiment, the first fixing plate is arranged at a first end of the guide rail, and the second end of the guide rail is provided with a second fixing plate; a first extending plate is arranged on the first fixing plate; a second extension plate is arranged on the second fixing plate; the first extension plate and the second extension plate are both provided with mounting holes.

According to a preferred embodiment, the top waist plate comprises a main plate, and a third extension plate is arranged on one side of the main plate; the first tie plate and the second tie plate are both hinged to the third extension plate; and a first included angle is formed between the third extending plate and the main plate.

According to a preferred embodiment, the hinge point of the first connecting plate and the top waist plate is a first hinge point, and the hinge point of the second connecting plate and the top waist plate is a second hinge point; the first hinge point and the second hinge point coincide.

A backrest support comprises a fixing frame and the waist supporting device, wherein: the fixing frame comprises two side plates; the waist supporting device is fixedly arranged between the two side plates.

According to a preferred embodiment, the waist support device further comprises a headrest device, wherein the headrest device is arranged between the two side plates and distributed on the upper side of the waist support device.

A seat unit at least comprises the backrest support.

The utility model discloses technical scheme has following advantage and beneficial effect at least:

the waist ejecting device of the utility model has simple structure, the position of the waist ejecting plate relative to the guide rail is adjusted by matching the slide block and the guide rail through the first connecting plate and the second connecting plate, and the driving structure of the first connecting plate and the second connecting plate is simplified through the matching of the slide block and the slide rail, so that the device has compact structure and occupies less space; simultaneously, the motion range of first even board is bigger, and under the same condition of first even board length, this structure can make the top waist board reach bigger height-adjusting under the effect of first even board, and the control range is big, and the practicality is strong.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings that are required to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention, and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic view of a first three-dimensional structure of a middle waist-supporting device of the present invention;

fig. 2 is a second schematic perspective view of the middle waist-supporting device of the present invention;

fig. 3 is a third schematic perspective view of the middle waist-supporting device of the present invention;

fig. 4 is a schematic front view of the middle waist-supporting device of the present invention;

FIG. 5 is a schematic cross-sectional view of section C-C of FIG. 4;

FIG. 6 is an enlarged view of a portion of the structure of FIG. 4 at A;

FIG. 7 is an enlarged view of a portion of the structure at B in FIG. 5;

fig. 8 is a schematic view of a first state of the middle waist-supporting device of the present invention;

fig. 9 is a schematic view of a second state of the middle waist-supporting device of the present invention;

fig. 10 is a third state diagram of the middle waist-supporting device of the present invention;

fig. 11 is a schematic view of a first three-dimensional structure of the middle backrest bracket of the present invention;

fig. 12 is a schematic view of a second three-dimensional structure of the middle backrest support of the present invention.

Icon: 1-fixed mount, 11-side plate, 12-second beam, 13-first beam, 14-third beam, 141-fixed hole, 2-waist-pushing device, 20-mounting hole, 21-waist-pushing plate, 211-third extending plate, 212-flanging, 213-main plate, 22 a-first hinge point, 22 b-second hinge point, 23-first connecting plate, 231-limit projection, 24-second connecting plate, 241-first stop, 242-second stop, 243-abdicating surface, 25-slider, 251-first fork, 252-connecting section, 253-sleeve, 26-guide rail, 261-sliding groove, 262-second fork, 27-driving piece, 271-driving screw, 28-first fixing plate, 281-first extending plate, 29-second fixing plate, 291-second extending plate, 3-headrest device, 31-fixed piece, 32-mounting cross bar.

Detailed Description

For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplification of the description, but do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

Referring to fig. 1 to 12, a waist supporting device includes: a guide rail 26; a slider 25 slidably attached to the guide rail 26; a first connecting plate 23, one end of which is hinged to the sliding block 25 and the other end of which is hinged to the top waist plate 21; a second link plate 24 having one end hinged to the guide rail 26 and the other end hinged to the top waist plate 21; and a driving member 27 for driving the slide block 25 to slide axially along the guide rail 26 so as to move the top waist plate 21 away from or close to the guide rail 26. The utility model discloses in, driving piece 27 drive slider 25 is at guide rail 26 endwise slip, and the in-process, first even board 23 cooperation second even board 24 forms the support to top waist board 21, and the distance between this top waist board 21 and the guide rail 26 can be along with first even board 23 and/or second even board 24 for guide rail 26's contained angle change increase or reduce to realize the altitude mixture control of top waist board 21.

In this embodiment, as shown in fig. 8, 9 and 10, the schematic structural diagrams of the waist-supporting device 2 in the first state, the second state and the third state are shown in sequence, when the waist-supporting device is in the first state, the waist-supporting device is in the first limit position and is in the storage state, and at this time, the first connecting plate 23 and the second connecting plate 24 both tend to be parallel to the guide rail 26, so that the waist-supporting device has a compact overall structure and occupies a small space; when the third state, this device is in the second extreme position, and is the extension state, and first link plate 23 and guide rail 26 tend to perpendicularly this moment, under the same circumstances of first link plate 23 length, can make top waist board 21 reach bigger adjustment height under the effect of first link plate 23, and accommodation is big, and the practicality is strong.

In the present embodiment, as shown in fig. 4 and 6, the hinge point of the first link plate 23 and the top waist plate 21 is a first hinge point 22a, and the hinge point of the second link plate 24 and the top waist plate 21 is a second hinge point 22b; the first connecting plate 23 is provided with a limiting bulge 231, and the limiting bulge 231 is distributed near the first hinge point 22 a; the second link plate 24 is provided with a first stopper 241 and a second stopper 242. In this embodiment, the first stopper 241 and the second stopper 242 are both distributed near the second hinge point 22 b. When the driving member 27 drives the slider 25 to slide axially along the guide rail 26, the limiting protrusion 231 moves between the first stopper 241 and the second stopper 242.

In this embodiment, the area between the first stopping block 241 and the second stopping block 242 is the moving area of the limiting protrusion 231, and the limiting protrusion 231 cooperates with the first stopping block 241 and the second stopping block 242 to limit the two limit positions of the waist supporting plate 21, so that the structural stability of the device is guaranteed and the safety is high. Specifically, when the position restricting protrusion 231 abuts against the first stopper 241, the top waist panel 21 is in the first limit position as shown in fig. 8; when the position restricting protrusion 231 abuts against the second stopper 242, the top waist panel 21 is in the second limit position as shown in fig. 10. In other embodiments, a guide groove may be formed on the second connecting plate 24, and the limiting protrusion 231 is slidably inserted into the guide groove. When the stopper projection 231 abuts against the end inside surface of the guide groove, the top waist panel 21 reaches the limit position.

Further, as shown in fig. 6, the second connecting plate 24 is configured with a relief surface 243, and the relief surface 243 is distributed between the first stopper 241 and the second stopper 242 and is disposed toward the limiting protrusion 231; the receding surface 243 has an arc shape. In this embodiment, the limiting protrusion 231 rotates around the first hinge point 22a, and the avoiding surface 243 extends along the rotation track of the limiting protrusion 231, so that the structure is compact.

Further, the first stopper 241 and the second stopper 242 are integrally formed with the second connecting plate 24. The second connecting plate 24 is convenient to produce and process and has high structural strength. Furthermore, as shown in fig. 6, the inner side surface of the first block 241 is smoothly transited to the receding surface 243, and the transition position is in the shape of an inward concave arc; the inner side surface of the first block 241 is smoothly transited to the receding surface 243, and the transition position is also in the shape of an inward concave arc. The design of circular-arc smooth transition can reduce the stress concentration of the junction between first dog 241 and second dog 242 respectively and the second even board 24 to guarantee the joint strength of first dog 241 and second dog 242 respectively and second even board 24, hoisting device's security. Meanwhile, in this embodiment, it is preferable that the limiting protrusion 231 has a cylindrical shape. The limiting protrusion 231 is designed to be cylindrical, so that when the limiting protrusion abuts against the first stop 241 and the second stop 242, the limiting protrusion can be adapted to the transition position between the first stop 241 and the second connecting plate 24, and can be adapted to the transition position between the second stop 242 and the second connecting plate 24, so that the contact area between the limiting protrusion 231 and the first stop 241 and the second stop 242 can be increased, the stability of the device structure can be improved, the structural compactness of the device can be improved, and the volume of the device can be reduced. As shown in particular in fig. 9 and 10.

In this embodiment, as shown in fig. 1 and 2, the first fixing plate 28 is disposed on the guide rail 26, and the second connecting plate 24 is hinged to the guide rail 26 through the first fixing plate 28. The first fixing plate 28 is in an "L" shape, and is connected to the guide rail 26, so that the hinge point of the second connecting plate 24 and the guide rail 26 (i.e. the hinge point of the second connecting plate 24 and the first fixing plate 28) is higher than the guide rail 26, and a space is provided for assembling the driving member 27; meanwhile, as shown in fig. 8, 9 and 10, since the second link plate 24 rotates around its hinge point with the guide rail 26 during the movement of the top waist plate 21, the top waist plate 21 may also be shifted to some extent in the axial direction of the guide rail 26 during the process of approaching or departing from the guide rail 26, and the shift amount here depends on the initial position of the second link plate 24 and the rotation angle of the second link plate 24 around its hinge point with the guide rail 26. According to the geometrical relationship, when the second link plate 24 is in the state shown in fig. 8, that is, the second link plate 24 is parallel to the guide rail 26, the distance by which the top waist plate 21 is offset by rotating it is minimum. Therefore, the first fixing plate 28 can enable the second connecting plate 24 and the guide rail 26 to be in a mutually parallel state after being hinged, so that the offset of the top waist plate 21 along the axial direction of the guide rail 26 is minimum when the second connecting plate 24 rotates at the same angle, the user experience is improved, and the practicability is high.

Preferably, as shown in fig. 2, 4, 5 and 7, the driving member 27 is fixedly mounted between the first fixing plate 28 and the guide rail 26. Specifically, the driving member 27 is fixed to a first end of the guide rail 26, a second fork 262 is disposed on an outer wall of the driving member 27, and the first fixing plate 28 is mounted on the second fork 262. The drive 27 here is an electric motor and the guide rail 26 is a hollow profile. In this embodiment, a drive screw 271 is rotatably mounted in the guide rail 26, an axial direction of the drive screw 271 is parallel to an axial direction of the guide rail 26, and the drive screw 271 is connected to an output shaft of the motor. The slide block 25 is slidably sleeved outside the guide rail 26. Further, as shown in fig. 3, a slide groove 261 is formed in the side wall of the guide rail 26 so as to extend in the axial direction thereof. A sleeve 253 in threaded transmission connection with the transmission screw 271 is arranged in the guide rail 26, the sleeve 253 is fixedly connected to the slide 25 through a connecting section 252, and the connecting section 252 penetrates through the sliding groove 261. In use, the motor drives the transmission screw 271 to rotate, so that the sleeve 253 moves along the axial direction of the transmission screw 271, namely the axial direction of the guide rail 26, and further drives the slide 25 to slide along the axial direction of the guide rail 26. It should be noted that in other embodiments, the first fixing plate 28 may also be directly mounted on the guide rail 26, that is, when the driving member 27 is disposed at the first end of the guide rail 26, the second fixing plate 28 is distributed between the second end of the guide rail 26 and the driving member 27.

In this embodiment, it is preferable that the slider 25 is provided with a first fork 251, and the first link plate 23 is hinged to the first fork 251 by a pin. Here, the first yoke 251 can limit the first link plate 23 so that it can rotate around the axis of the pin shaft. In this embodiment, the slider 25, the connecting section 252 and the sleeve 253 are integrally formed. The strength is high.

In this embodiment, the second end of the guide rail 26 is an open end for easy installation, and the second end of the guide rail 26 is provided with a second fixing plate 29 for closing the second end of the guide rail 26 after installation. Here a second fixing plate 29 is detachably mounted to the second end of the guide rail 26 by means of screws or bolts. Further, a first extension plate 281 is disposed on the first fixing plate 28; a second extension plate 291 is disposed on the second fixing plate 29; the first extension plate 281 and the second extension plate 291 are each provided with a mounting hole 20. The first extension board 281 and the second extension board 291 are used for fixedly connecting the waist-supporting device 2 with other structures. Preferably, in this embodiment, the first fixing plate 28 is hinged to the second fork frame 262 by a pin. In use, the lumbar support device is fixedly mounted to other structures by the first extension plate 281 and the second extension plate 291, and the first fixing plate 28 is hinged to the driving member 27 by the second fork 262, thereby facilitating the mounting of the lumbar support device. Specifically, when the extension plate 291 is installed, the first extension plate 291 may be fixedly installed with another structure, and finally, the angle of the second extension plate 281 with respect to the driving member 27 may be adjusted according to the installation environment, and then the extension plate may be fixedly installed.

In this embodiment, it is preferable that the first hinge point 22a and the second hinge point 22b coincide. When the first hinge point 22a and the second hinge point 22b are overlapped, the guide rail 26, the first connecting plate 23 and the second connecting plate 24 form a triangular structure, so that the waist supporting device 2 has better structural stability and good pressure bearing effect.

It should be noted that when the first hinge point 22a and the second hinge point 22b are overlapped, the top waist plate 21 can freely rotate around the first hinge point 22a and the second hinge point 22 b. When the fixing frame is applied to the backrest of the functional sofa or the functional seat, that is, after the fixing frame is installed on the fixing frame 1, since the backrest of the functional sofa or the functional seat is covered with the sponge, the leather, the fabric or the like, the outer side of the fixing frame 1 in the embodiment is covered with the sponge, the leather, the fabric or the like to form a soft bag after the waist-pushing device 2 is installed, and the outer bags are assembled with the fixing frame 1 and have tension, the waist-pushing plate 21 can keep vertically ascending without two-side toppling when being away from the guide rail 26 under the action of the driving piece 27 (that is, the inner side of the outer bag is pressed).

Preferably, in this embodiment, the top waist panel 21 includes a main panel 213, and a third extending panel 211 is disposed on one side of the main panel 213; the first connecting plate 23 and the second connecting plate 24 are both hinged to the third extending plate 211; the third extending plate 211 and the main plate 213 form a first included angle therebetween. Here, the third extending plate 211 is used to connect the first connecting plate 23 and the second connecting plate 24, and the first included angle between the third extending plate 211 and the main plate 213 is 90 °. In other embodiments, the specific angle of the first included angle may be set as required, so that the main plate 213 can press the waist of the user in the largest area after the waist-supporting device 2 is mounted on the fixing frame 1.

Further, as shown in fig. 2, the other side of the main plate 213 is provided with a flange 212. The turned-over edge 212 can increase the strength of the top waist panel 21, and can improve the comfort of the top waist panel 21 when pressing the waist of the user, thereby avoiding discomfort caused by the direct action of the edge of the top waist panel 21 on the user.

In the present embodiment, there is also provided a backrest support, as shown in fig. 11 and 12, the backrest support includes a fixed frame 1 and a lumbar support 2 in the present embodiment, wherein: the fixed frame 1 comprises two side plates 11 which are arranged in parallel; the waist-supporting device 2 is fixedly mounted between the two side plates 11. Further, a first beam 13, a second beam 12 and a third beam 14 are respectively arranged between the two side plates 11, wherein the first beam 13 is distributed near the upper ends of the side plates 11, the third beam 14 is distributed near the lower ends of the side plates 11, and the second beam 12 is distributed between the first beam 13 and the third beam 14. In this embodiment, the lumbar support device 2 is fixedly mounted on the third cross member 14. Specifically, the third cross member 14 is provided with fixing holes 141 corresponding one-to-one to the mounting holes 20, and in use, the first extension plate 281 and the second extension plate 291 are abutted to the third cross member 14 so that the mounting holes 20 correspond to the fixing holes 141, and then the lumbar support device 2 is fixedly mounted to the fixing frame 1 by inserting screws or bolts into the mounting holes 20 and the fixing holes 141. The first cross member 13, the second cross member 12 and the third cross member 14 here serve to increase the structural stability of the fastening frame 1.

Further, the backrest support further comprises a headrest device 3, and the headrest device 3 is arranged between the two side plates 11 and distributed on the upper side of the waist supporting device 2. The headrest device 3 herein is integrally referred to the headrest assembly, the fixing member 31 and the mounting cross bar 32 disclosed in chinese patent with publication number CN215533019U, that is, the headrest device 3 in this embodiment is formed by combining the headrest assembly, the fixing member 31 and the mounting cross bar 32 disclosed in chinese patent with publication number CN215533019U, and is not described herein again for the prior art. It should be noted that the fixing member 31 is fixedly mounted on the side plate 11 by a screw or a bolt. In other embodiments, the lumbar support device 2 may be integrally connected to the headrest device 3. Specifically, the first and second extension plates 281 and 291 are mounted on the mounting rail 32 by screws or bolts.

The embodiment also provides a seat unit, which at least comprises the backrest bracket. The seat unit can realize the adjustment of the backrest of the seat unit through the waist ejecting device 2 and the headrest device 3, thereby improving the experience of the user using the seat unit.

The technical means disclosed by the scheme of the present invention is not limited to the technical means disclosed by the above embodiments, but also includes the technical scheme formed by the arbitrary combination of the above technical features. It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications are also considered as the protection scope of the present invention.

Claims (10)

1. A lumbar support device, comprising:

a guide rail (26);

a slider (25) slidably attached to the guide rail (26);

a first connecting plate (23) with one end hinged to the sliding block (25) and the other end hinged to a waist-supporting plate (21);

a second link plate (24) having one end hinged to the guide rail (26) and the other end hinged to the top waist plate (21); and

the driving piece (27) is used for driving the sliding block (25) to axially slide along the guide rail (26) so as to enable the top waist plate (21) to be far away from or close to the guide rail (26).

2. The top waist device according to claim 1, characterized in that the hinge point of the first connecting plate (23) to the top waist plate (21) is a first hinge point (22 a);

a limiting bulge (231) is arranged on the first connecting plate (23), and the limiting bulge (231) is distributed close to the first hinge point (22 a);

a first stop block (241) and a second stop block (242) are arranged on the second connecting plate (24);

when the driving piece (27) drives the sliding block (25) to axially slide along the guide rail (26), the limiting protrusion (231) moves between the first stop block (241) and the second stop block (242).

3. The waist ejecting device according to claim 2, wherein the second connecting plate (24) is provided with a relief surface (243), and the relief surface (243) is distributed between the first stop block (241) and the second stop block (242) and is arranged towards the limiting protrusion (231).

4. The lumbar support device according to claim 1, further comprising a first fixing plate (28) provided to the guide rail (26) or the driving member (27), wherein the second link plate (24) is hinged to the guide rail (26) by the first fixing plate (28).

5. The lumbar support device according to claim 4, characterized in that the first fixing plate (28) is provided at a first end of the guide rail (26), and a second end of the guide rail (26) is provided with a second fixing plate (29);

a first extension plate (281) is arranged on the first fixing plate (28);

a second extension plate (291) is disposed on the second fixing plate (29);

the first extension plate (281) and the second extension plate (291) are each provided with a mounting hole (20).

6. The top waist arrangement according to any one of claims 1-5, characterized in that said top waist panel (21) comprises a main panel (213), one side of said main panel (213) being provided with a third extension panel (211);

the first tie plate (23) and the second tie plate (24) are both hinged to the third extension plate (211);

and a first included angle is formed between the third extending plate (211) and the main plate (213).

7. The waist-pushing device according to claim 1, characterized in that the hinge point of the first link plate (23) to the waist-pushing plate (21) is a first hinge point (22 a), and the hinge point of the second link plate (24) to the waist-pushing plate (21) is a second hinge point (22 b);

the first hinge point (22 a) and the second hinge point (22 b) coincide.

8. A backrest support, characterized in that it comprises a fixed frame (1) and a lumbar support (2) according to any one of claims 1-7, wherein:

the fixing frame (1) comprises two side plates (11);

the waist supporting device (2) is fixedly arranged between the two side plates (11).

9. A back rest support according to claim 8, further comprising a headrest device (3), wherein the headrest device (3) is arranged between the two side plates (11) and distributed on the upper side of the waist support device (2).

10. A seating unit comprising at least a backrest support as claimed in claim 8 or 9.

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