CN213308589U

CN213308589U - Adjustable sofa backrest

Info

Publication number: CN213308589U
Application number: CN202020937015.1U
Authority: CN
Inventors: 李云海; 姚有贵; 屠家会; 厉威杨
Original assignee: Kuka Home Co Ltd
Current assignee: Kuka Home Co Ltd
Priority date: 2020-05-28
Filing date: 2020-05-28
Publication date: 2021-06-01
Anticipated expiration: 2030-05-28

Abstract

The utility model relates to a sofa or a seat with an adjusting function; the adjustable sofa backrest comprises a balance plate (3) and multifunctional supports (4) which are respectively arranged on the left side and the right side of the balance plate (3), one end of a motor is connected with a motor fixing beam (2), the other end of the motor is connected with the back of the balance plate (3), and the balance plate (3) is pushed by the motor (1) to extend the multifunctional supports (4) and enable the tops of the multifunctional supports (4) to bend downwards and the bottoms of the multifunctional supports to tilt upwards; the top of the multifunctional support (4) corresponds to the headrest part of the sofa backrest, the bottom of the multifunctional support (4) corresponds to the waist support of the sofa backrest, and the front of the balance plate (3) corresponds to the backrest body of the sofa backrest. The utility model discloses a sofa backrest compares in traditional function sofa backrest provides longer back body and the headrest and the waist support function that more nimble is movable, and then has promoted sofa backrest's practical travelling comfort.

Description

Adjustable sofa backrest

Technical Field

The utility model relates to the field of living furniture or office furniture, in particular to a functional sofa or chair with an adjusting function to change the posture of a user; in particular to a sofa backrest which can be extended and contracted and the headrest and the waist support of which can be moved.

Background

With the increasing living standard, the sofa with single posture is gradually marginalized by the market. Instead, the functional sofa has a plurality of different shapes simultaneously and can be combined and switched to change the sitting posture of the user.

Functional sofas typically include a back portion, a cushion portion, and a footrest portion; the three parts are sequentially linked and the angles of the three parts are changed, so that the functional sofa can be switched among sitting posture, semi-lying posture and lying posture.

The functional sofa can be switched among the three forms, so that the back and the legs of the user can obtain comfortable support at different angles, and the physical comfort of the user is improved. However, the user's head and waist often lack the extensibility and comfort support that is compatible with the back and legs.

In order to solve the above problems, sofa manufacturers have developed an attachment structure in which a movable headrest and a movable lumbar support are provided at upper and lower portions of a backrest portion, respectively. These attachment structures effect autonomous or dependent motion through one or more sets of actuators and a drive mechanism to cause corresponding changes in the head restraint and lumbar support as the angle of the back portion is changed. The ultimate goal is to have the head rest and lumbar support provide a malleable, comfortable support for the user's head and waist that is compatible with the back and legs.

However, current actuators for moving head restraints and lumbar supports have some design drawbacks, such as:

1. the actuator is too bulky:

the inside of the backrest part already comprises an iron frame and a wooden block for installing the coating sponge, and the usable space of the coating sponge can be occupied after the actuating mechanism and the driving device are added. Thus, the most direct effect of this is that the overall thickness of the back rest portion is increased, and the thickness of the back rest sponge that makes direct contact with the back of the user is reduced and the comfort of the user is reduced.

2. The actuator cannot change the length of the headrest or copy portion:

the conventional actuator operates only the headrest and the lumbar support of the backrest portion so that both of them operate in accordance with the rotation of the backrest portion, but does not change the length (or height) of the headrest or the entire backrest portion. Thus, when the user is tall or the sofa backrest is small overall, there is no way to provide adequate comfort support for the user's head.

3. The connection relationship among the components is unreliable, and the running stability of the actuating mechanism is poor:

currently, the actuators are usually independently arranged on two sides of the iron frame of the backrest part, and the actuators on the two sides are not directly connected and only directly drive the actuators on the two sides to act by a driving device. Therefore, after long-term use, the actuating mechanisms on the two sides can generate asynchronous actions when acting, and the phenomena can be converted into friction, abnormal sound and impact vibration and act on the back of a user through the backrest sponge, and finally the comfort experience of the user can be reduced.

SUMMERY OF THE UTILITY MODEL

The utility model aims to overcome above-mentioned defect, provide an actuating mechanism compact structure, the reliable sofa back of operation steadily, and this sofa back's adjustable length, headrest and waist are by can linking up the action.

In order to achieve the above object, the present invention is realized as follows:

a telescopic sofa backrest with movable headrest and waist support comprises a driving motor, a motor fixing beam, a balance plate and multifunctional supports arranged on the left side and the right side of the balance plate respectively, wherein one end of the motor is connected with the motor fixing beam, the other end of the motor is connected with the back of the balance plate, and the balance plate extends the multifunctional supports under the pushing of the motor and enables the tops of the multifunctional supports to bend downwards and the bottoms of the multifunctional supports to warp upwards; the top of the multifunctional support corresponds to the headrest part of the sofa backrest, the bottom of the multifunctional support corresponds to the waist support of the sofa backrest, and the front of the balance plate corresponds to the backrest body of the sofa backrest.

The multifunctional support of the adjustable sofa backrest realizes the telescopic function through a pair of sliding friction components; the headrest part and the waist support of the sofa backrest realize continuous action under the pushing of the multifunctional support.

The adjustable sofa backrest can realize the telescopic function through a group of rolling friction components by the bracket; the headrest part and the waist support of the sofa backrest realize continuous action under the pushing of the multifunctional support.

The telescopic sofa backrest with the movable headrest and waist support comprises a plate mounting part, a slip sheet, a headrest mounting plate, a waist support mounting plate and a pull rod, wherein the plate mounting part is used for being connected with a balance plate, the slip sheet is arranged in a sliding manner relative to the plate mounting part, the headrest mounting plate and the waist support mounting plate are respectively and rotatably arranged at the top and the bottom of the plate mounting part, the pull rod is used for connecting the headrest mounting plate and the waist support mounting plate, a pulley is arranged on one side of the waist support mounting plate, an upper blocking sheet and a lower blocking sheet are arranged on the slip sheet and used for limiting the moving distance of the pulley, and one side of the headrest mounting plate is rotatably connected; a positioning column is arranged on the sliding sheet, a sliding groove is arranged on the plate mounting piece, and the positioning column penetrates into the sliding groove; so, when the motor promoted the balance plate, the dress board piece of being connected with the balance plate began to follow the spout action promptly, and then made the balance plate slide from top to bottom along spout place orbit, and at this in-process, the waist held in the palm the mounting panel and received the restriction of separation blade and only rotatable after the one end distance that slides from top to bottom along with dress board piece, and it makes through the pull rod and drags the action and makes the headrest mounting panel buckle downwards this moment to the headrest mounting panel.

The telescopic sofa backrest with the movable headrest and waist support comprises a rolling friction assembly in the multifunctional support, a slide sheet, a slide rail assembly, a base sheet, a headrest mounting plate, a waist support mounting plate and a pull rod, wherein the rolling friction assembly comprises a plate mounting piece connected with a balance plate; the sliding rail component comprises a sliding rail bottom fixedly arranged on the base plate and a sliding rail piece connected with the sliding rail bottom in a sliding manner, the sliding piece is connected with the sliding rail piece, a headrest mounting plate, a mounting plate and a waist support mounting plate are sequentially arranged on the upper part, the middle part and the lower part of the sliding piece respectively, the headrest mounting plate, the mounting plate and the waist support mounting plate are in rotary connection with the sliding piece, the mounting plate is fixedly connected with the sliding piece, and the headrest mounting plate and the waist support mounting plate are connected through a pull rod; the waist support mounting plate is provided with an arc-shaped sliding chute, the sliding sheet is provided with a positioning column, and the positioning column penetrates into the arc-shaped sliding chute; so, when the motor promoted the balance plate, the dress plate spare of being connected with the balance plate drove the gleitbretter promptly and slided from top to bottom along slide rail assembly place orbit, and at this in-process, the waist held in the palm the mounting panel and received the restriction of reference column on its arc spout and the gleitbretter and only upwards rotate, and it makes through the pull rod and drags the action and makes the headrest mounting panel buckle downwards to the headrest mounting panel.

The telescopic sofa backrest with the movable headrest and the movable waist support is characterized in that a nylon lining is sleeved on the positioning column, and the pulley arranged on the waist support mounting plate is also made of nylon, so that the pulley made of the nylon lining and the nylon material enables the plate loading plate and the waist support mounting plate to form a buffer layer when acting.

The telescopic sofa backrest with the movable headrest and the movable waist support is characterized in that a tension spring is arranged between the base plate and the waist support mounting plate, the tension spring is connected with the base plate and the waist support mounting plate through rivets respectively, and the axis of the tension spring is parallel to the sliding rail assembly.

The sofa backrest is telescopic, the headrest and the waist support of the sofa backrest are movable, an upper limiting rivet and a lower limiting rivet are arranged on the base plate along the up-down sliding track of the waist support mounting plate, and the two limiting rivets are used for limiting the up-down sliding amplitude of the waist support mounting plate along with the sliding sheet.

When the sofa backrest is in a folded state, the highest point positions of the headrest mounting plate, the pull rod and the waist support mounting plate in the multifunctional support are in the same plane or the highest point position of the pull rod does not exceed the axis formed by the highest point positions of the headrest mounting plate and the waist support mounting plate; namely, when the multifunctional support is folded, the front surfaces of the headrest mounting plate, the pull rod and the waist support mounting plate in the multifunctional support are positioned in the same plane or form an inward concave plane in the side projection.

The utility model discloses according to above-mentioned design, provided a brand-new structure that can make sofa back body adjustable length and headrest and waist support realization linkage. This sofa backrest has the following advantages:

1. the multifunctional support is arranged on the two sides of the sofa backrest, so that the part of the sofa backrest, which is directly contacted with the back of a user, is prevented from being invaded; so, when the sofa back is same thickness, the utility model discloses a sofa back can use thicker back sponge to cooperate the balanced board of large tracts of land, can support the experience for the user provides better back.

2. The left and right sides of the multifunctional support which are originally mutually independent are connected through the large-area balance plate, so that a stable enough integral executing mechanism is formed, and the problem that the mutually independent executing mechanisms are easy to generate asynchronous actions during actions is avoided. The integral executing mechanism also takes a slide rail as a guide mechanism in action; the whole sofa backrest is stable and smooth when the shape of the sofa backrest is changed, and the phenomena of abnormal friction and noise and various rushing phenomena in the shape conversion process of the traditional functional sofa are overcome.

3. When the scalable multi-functional support through the friction that adopts the resistance to be little or the form that rolls realizes sofa back body length scalable function, the flexible stroke of further relying on multi-functional support makes headrest and the waist in the sofa back subassembly hold in the palm and realize ejecting or the linking up action of flattening under the promotion of the flexible in-process of multi-functional support, thereby in this sofa back's use, when sofa back's angle changes, headrest and waist back position make the change simultaneously, and then provide extra bracketing effect to user's head, waist, thereby user's comfortable nature experience has been promoted.

Drawings

Fig. 1 is a schematic view of the sofa backrest disclosed in the present invention.

Fig. 2 is a schematic structural diagram of the multifunctional bracket of the present invention.

Fig. 3 is a schematic structural diagram of the multifunctional bracket of the present invention.

Fig. 4 is a third schematic structural view of the multifunctional bracket of the present invention.

Fig. 5 is a schematic structural diagram of the multifunctional bracket of the present invention.

Fig. 6 is a schematic view of the sofa backrest according to the present invention.

Fig. 7 is a schematic view of the operation of the sofa backrest of the present invention.

Detailed Description

The invention is further illustrated by the following specific examples.

Example one

As shown in fig. 1, 6 and 7, a retractable sofa backrest with movable headrest and waist support comprises a driving motor 1, a motor fixing beam 2, a balance plate 3 and multifunctional supports 4 respectively arranged at the left side and the right side of the balance plate 3, wherein one end of the motor is connected with the motor fixing beam 2, the other end of the motor is connected with the back of the balance plate 3, and the balance plate 3 extends the multifunctional supports 4 under the pushing of the motor 1 and enables the tops of the multifunctional supports 4 to bend downwards and the bottoms of the multifunctional supports 4 to tilt upwards; the top of the multifunctional support 4 corresponds to the headrest part of the sofa backrest, the bottom of the multifunctional support 4 corresponds to the waist support of the sofa backrest, and the front of the balance plate 3 corresponds to the backrest body of the sofa backrest.

In this embodiment, the support that has held in the palm and the function of action actuating mechanism through multi-functional support concurrently, wherein, multi-functional support is through a motor drive and realize the tensile of sofa back body and the action drive that the headrest is curved down, the waist held in the palm upwarp, thereby makes the utility model discloses a sofa back compares and provides longer back body and the headrest and the waist that more nimble is movable and hold in the palm the function in traditional function sofa back, and then has promoted sofa back's practical travelling comfort.

Example two

The second embodiment is an improvement of the first embodiment, and particularly, is directed to an improvement of the multifunctional bracket in the first embodiment.

As shown in fig. 5, the sofa backrest is retractable and has movable headrest and lumbar support, the multifunctional bracket 4 comprises a plate-mounting member 5 connected with the balance plate 3, a sliding sheet 6 slidably arranged relative to the plate-mounting member 5, headrest mounting plates 7 and lumbar support mounting plates 8 rotatably arranged at the top and bottom of the plate-mounting member 5 respectively, and a pull rod 9 connecting the headrest mounting plates 7 and the lumbar support mounting plates 8, wherein a pulley 10 is arranged at one side of the lumbar support mounting plate 8, an upper blocking sheet 11 and a lower blocking sheet 11 limiting the moving distance of the pulley 10 are arranged on the sliding sheet 6, and one side of the headrest mounting plate 7 is rotatably connected with the plate-mounting member 5; a positioning column 12 is arranged on the sliding sheet 6, a sliding chute 13 is arranged on the plate installing piece 5, and the positioning column 12 penetrates into the sliding chute 13; so, when motor 1 promoted balance plate 3, the dress plate spare 5 of being connected with balance plate 3 begins to move along spout 13 promptly, and then makes balance plate 3 slide from top to bottom along the orbit at spout 13 place, and at this in-process, waist holds in the palm mounting panel 8 and receives the restriction of separation blade 11 and only can rotate after the one end distance that slides from top to bottom along with dress plate spare 5, and it makes the action of pulling and makes headrest mounting panel 7 buckle downwards through pull rod 9 this moment to headrest mounting panel 7.

In the embodiment, a plate capable of sliding relatively is adopted as a supported multifunctional support, in the multifunctional support, the function that a sofa backrest body can be stretched is realized through the relative sliding between a sliding sheet 6 which is fixed relatively and a plate loading piece 5 which can slide relatively, secondly, the rotatable headrest mounting plate 7 and the waist support mounting plate 8 are arranged on the plate loading piece 5, the headrest mounting plate 7 and the waist support mounting plate 8 are linked with each other through a pull rod 9, and after the waist support mounting plate 8 is limited by the sliding sheet 6 to rotate upwards, the headrest mounting plate 7 rotates downwards under the pull force of the pull rod 9, so that the linkage function of the headrest and the waist support in the sofa backrest is realized.

EXAMPLE III

The third embodiment is an improvement of the first embodiment, specifically an improvement of the multifunctional support in the first embodiment, which is parallel to the second embodiment.

As shown in fig. 2, 3 and 4, the sofa backrest which can be extended and contracted and has the movable headrest and waist support is characterized in that the multifunctional bracket 4 comprises a plate mounting member 5' for connecting with the balance plate 3, and further comprises a sliding sheet 14, a sliding rail assembly 15, a base plate 16, a headrest mounting plate 7, a waist support mounting plate 8 and a pull rod 9; the slide rail assembly 15 comprises a slide rail bottom 151 fixedly arranged on the base plate 16 and a slide rail piece 152 connected with the slide rail bottom 151 in a sliding manner, the slide rail 14 is connected with the slide rail piece 152, a headrest mounting plate 7, a plate mounting plate 5 'and a waist support mounting plate 8 are respectively and sequentially arranged at the upper part, the middle part and the lower part of the slide rail 14, the headrest mounting plate 7, the waist support mounting plate 8 and the slide rail 15 are in rotary connection, the plate mounting plate 5' is fixedly connected with the slide rail 15, and the headrest mounting plate 7 and the waist support mounting plate 8 are connected through a pull rod 9; an arc-shaped sliding groove 17 is formed in the waist support mounting plate 8, a positioning column 18 is arranged on the sliding sheet 15, and the positioning column 18 penetrates into the arc-shaped sliding groove 17; therefore, when the motor 1 pushes the balance plate 3, the mounting plate 5' connected with the balance plate 3 drives the sliding piece 15 to slide up and down along the track of the sliding rail assembly 15, in the process, the waist support mounting plate 8 is limited by the arc-shaped sliding groove 17 and the positioning column 18 on the sliding piece 15 and only rotates upwards, and the pull rod 9 pulls the headrest mounting plate 7 and enables the headrest mounting plate 7 to bend downwards.

As can be seen from the second and third embodiments, the multifunctional support of the sofa backrest provided by the present invention can achieve the length expansion function through the second part which can relatively generate displacement, preferably in the form of an assembly which can directly rub between the two parts, or in the form of a third movable assembly, especially a sliding assembly, which is added between the two parts, so as to achieve the length expansion function of the multifunctional support.

The telescopic sofa backrest with the movable headrest and waist support is characterized in that a nylon lining is sleeved on the positioning column 12, the pulley 10 arranged on the waist support mounting plate 8 is also made of nylon, and thus the board mounting piece 5 and the waist support mounting plate 8 form a buffer layer during action through the nylon lining and the pulley 10 made of nylon.

The sofa backrest is telescopic, the headrest and the waist support of the sofa backrest are movable, a tension spring 19 is arranged between the base plate 16 and the waist support mounting plate 8, the tension spring 19 is respectively connected with the base plate 16 and the waist support mounting plate 8 through rivets, and the axial lead of the tension spring 19 is parallel to the sliding rail assembly 15.

The sofa backrest is telescopic, the headrest and the waist support of the sofa backrest are movable, an upper limiting rivet 20 and a lower limiting rivet 21 are arranged on the base plate 16 along the up-down sliding track of the waist support mounting plate 8, and the two limiting rivets are used for limiting the up-down sliding amplitude of the waist support mounting plate 8 along with the sliding sheet.

In this embodiment, the function of the support and the action executing mechanism of the backrest, the headrest and the lumbar support of the sofa are also fulfilled by the multifunctional support. Wherein, multi-functional support is through a motor drive and realize the action drive to stretching of sofa backrest body and headrest recurvation, waist support upwarp, thereby make the utility model discloses a sofa backrest compares and provides longer backrest body and the headrest and the waist support function of more nimble movable in traditional function sofa backrest, and then has promoted sofa backrest's practical travelling comfort.

Further, this embodiment has a better use experience than the second embodiment because:

1. the sliding guide is realized through the sliding rail assembly, the problem that the guide sliding chute and the guide post are damaged due to the fact that a sofa backrest is extruded by the back for a long time when the traditional guide sliding chute is used as a sliding guide structure is solved, and the multifunctional support can be smoother when the multifunctional support is extended through the sliding rail assembly;

2. the waist support mounting plate can move along with the sliding motion of the sliding sheet and the plate mounting piece in real time by adding the tension spring, and the waist support adjusting amplitude is more sensitive;

the advantages of the first, second and third embodiments are as follows:

as shown in fig. 3, 4 and 5, in the retractable sofa backrest with the movable headrest and lumbar support, when in a folded state, the highest point positions of the headrest mounting plate 7, the pull rod 9 and the lumbar support mounting plate 8 in the multifunctional support are in the same plane or the highest point position of the pull rod 9 is not more than the axis formed by the highest point positions of the headrest mounting plate 7 and the lumbar support mounting plate 8; namely, in the folded state, the front surfaces of the headrest mounting plate 7, the pull rod 9 and the waist support mounting plate 8 in the multifunctional support 4 are positioned in the same plane or form an inner concave plane in the side projection. The utility model discloses according to above-mentioned design, provided a brand-new structure that can make sofa back body adjustable length and headrest and waist support realization linkage.

To the above embodiments and the advantages thereof, the sofa backrest provided by the present invention has the following advantages:

Claims

1. An adjustable sofa backrest comprises a driving motor (1), and is characterized in that: the multifunctional electric motor is characterized by further comprising a motor fixing beam (2), a balance plate (3) and multifunctional supports (4) which are arranged on the left side and the right side of the balance plate (3) respectively, wherein one end of the motor is connected with the motor fixing beam (2), the other end of the motor is connected with the back face of the balance plate (3), and the balance plate (3) is pushed by the motor (1) to extend the multifunctional supports (4) and enable the tops of the multifunctional supports (4) to bend downwards and the bottoms of the multifunctional supports (4) to warp upwards; the top of the multifunctional support (4) corresponds to the headrest part of the sofa backrest, the bottom of the multifunctional support (4) corresponds to the waist support of the sofa backrest, and the front of the balance plate (3) corresponds to the backrest body of the sofa backrest.

2. The adjustable sofa backrest according to claim 1, wherein: the multifunctional support realizes the telescopic function through a pair of sliding friction components; the headrest part and the waist support of the sofa backrest realize continuous action under the pushing of the multifunctional support.

3. The adjustable sofa backrest according to claim 1, wherein: the functional bracket realizes a telescopic function through a group of rolling friction components; the headrest part and the waist support of the sofa backrest realize continuous action under the pushing of the multifunctional support.

4. The adjustable sofa backrest according to claim 1 or 2, wherein: the sliding friction component in the multifunctional support (4) comprises a mounting plate (5) connected with a balance plate (3), and further comprises a sliding sheet (14) which is arranged in a sliding mode relative to the mounting plate (5), a headrest mounting plate (7) and a waist support mounting plate (8) which are respectively and rotatably arranged at the top and the bottom of the mounting plate (5), and a pull rod (9) which connects the headrest mounting plate (7) and the waist support mounting plate (8), wherein a pulley (10) is arranged on one side of the waist support mounting plate (8), an upper blocking sheet (11) and a lower blocking sheet (11) which limit the moving distance of the pulley (10) are arranged on the sliding sheet (14), and one side of the headrest mounting plate (7) is rotatably connected with the mounting plate (5); set up reference column (12) and set up spout (13) on dress board spare (5) on gleitbretter (14), reference column (12) penetrate in spout (13).

5. The adjustable sofa backrest according to claim 1 or 3, wherein: the rolling friction assembly in the multifunctional support (4) comprises a plate mounting piece (5') used for being connected with the balance plate (3), and further comprises a sliding sheet (14), a sliding rail assembly (15), a base sheet (16), a headrest mounting plate (7), a waist support mounting plate (8) and a pull rod (9); slide rail set spare (15) including fixed slide rail end (151) that sets up on base piece (16) and slide rail piece (152) with slide rail end (151) sliding connection, gleitbretter (14) are connected with slide rail piece (152), upper portion, middle part and the lower part of gleitbretter (14) set up headrest mounting panel (7) according to the preface respectively, dress board spare (5 ') and waist hold in the palm mounting panel (8) and headrest mounting panel (7) and waist hold in the palm mounting panel (8) and gleitbretter (14) be connected for rotating and dress board spare (5') and gleitbretter (14) be fixed connection, still be connected through pull rod (9) between headrest mounting panel (7) and the waist holds in the palm mounting panel (8).

6. The adjustable sofa backrest according to claim 4, wherein: the positioning column (12) is sleeved with a nylon bush, the pulley (10) arranged on the waist support mounting plate (8) is also made of nylon, and thus the board mounting piece (5) and the waist support mounting plate (8) form buffer layers when the board mounting piece and the waist support mounting plate move through the nylon bush and the pulley (10) made of nylon.

7. The adjustable sofa backrest according to claim 5, wherein: a tension spring (19) is arranged between the base plate (16) and the waist support mounting plate (8), the tension spring (19) is respectively connected with the base plate (16) and the waist support mounting plate (8) through rivets, and the axial lead of the tension spring (19) is parallel to the sliding rail component (15).

8. The adjustable sofa backrest of claim 3, wherein: an upper limiting rivet (20) and a lower limiting rivet (21) are arranged on the base plate (16) along the up-down sliding track of the waist support mounting plate (8), and the two limiting rivets are used for limiting the up-down sliding amplitude of the waist support mounting plate (8) along with the sliding sheet.

9. The adjustable sofa backrest according to claim 4, wherein: when the multifunctional support is folded, the highest point positions of the headrest mounting plate (7), the pull rod (9) and the waist support mounting plate (8) in the multifunctional support are in the same plane or the highest point position of the pull rod (9) does not exceed the axis formed by the highest point positions of the headrest mounting plate (7) and the waist support mounting plate (8); namely, when the multifunctional support is folded, the front surfaces of the headrest mounting plate (7), the pull rod (9) and the waist support mounting plate (8) in the multifunctional support (4) are positioned in the same plane or form an inward concave plane in the projection of the side part.

10. The adjustable sofa backrest according to claim 5, wherein: when the multifunctional support is folded, the highest point positions of the headrest mounting plate (7), the pull rod (9) and the waist support mounting plate (8) in the multifunctional support are in the same plane or the highest point position of the pull rod (9) does not exceed the axis formed by the highest point positions of the headrest mounting plate (7) and the waist support mounting plate (8); namely, when the multifunctional support is folded, the front surfaces of the headrest mounting plate (7), the pull rod (9) and the waist support mounting plate (8) in the multifunctional support (4) are positioned in the same plane or form an inward concave plane in the projection of the side part.