CN217827308U

CN217827308U - Sofa bed with foldable backrest and inserting sheet hinging assembly used by same

Info

Publication number: CN217827308U
Application number: CN202222068953.4U
Authority: CN
Inventors: 汪昌友
Original assignee: Dongguan Huayuan Intelligent Furniture Co ltd
Current assignee: Dongguan Huayuan Intelligent Furniture Co ltd
Priority date: 2022-08-05
Filing date: 2022-08-05
Publication date: 2022-11-18
Anticipated expiration: 2032-08-05

Abstract

The utility model discloses a backrest folding sofa bed and an inserting sheet hinge assembly used by the backrest folding sofa bed, the backrest folding sofa bed comprises a bottom frame, a backrest, a cushion and handrails, the handrails are arranged at two sides of the bottom frame, the backrest is arranged at the rear side of the bottom frame through the inserting sheet hinge assembly, the cushion is placed on the bottom frame, the inserting sheet hinge assembly comprises an inserting sleeve fixed at the rear side of the bottom frame, an inserting sheet inserted and fixed in the inserting sleeve from top to bottom and a support plate hinged with the upper end of the inserting sheet, the support plate and the backrest are fixed to form a support for the rear end face of the backrest, the cushion is arranged on a telescopic support frame, and the telescopic support frame can be retractably placed on the bottom frame to form a sofa state; after the telescopic support frame is stretched, the end part of the telescopic support frame is abutted against the front end of the underframe, and the backrest is rotated forwards through the support plate relative to the inserting sheet to abut against the upper end surface of the underframe and/or the telescopic support frame so as to form a sofa bed state.

Description

Sofa bed with foldable backrest and inserting sheet hinging assembly used by same

The technical field is as follows:

the utility model relates to the technical field of furniture products, in particular to a backrest folding sofa bed and an inserting sheet hinging component used by the backrest folding sofa bed.

Background art:

with the rapid development of social economy, modern living room arrangement is advocated succinctly, and multifunctional furniture becomes more and more popular. The sofa bed is a sofa bed, and refers to furniture capable of being used as both a sofa and a bed. Modern living room arrangement is highly appreciated, and multifunctional furniture is becoming more and more popular choice, and the sofa bed is one of them. In a small-sized living room, a sofa bed is necessary to meet the occasional residential needs of visitors. Normally, the sofa bed can be placed in a living room or a study room and serves as a sofa; at night, a guest opens the sofa bed and lays bedding to form a bed. In common house types such as a three-room and two-room, the sofa bed can be outside the sleeping bed for people to sleep, and the sofa bed helps the master to deal with the occasional visits of a plurality of guests, and is very convenient to use.

The sofa bed comprises an underframe, armrests arranged on two sides of the underframe, a backrest arranged at the rear end of the underframe, a movable frame arranged at the front end of the underframe and capable of retracting relative to the underframe, and a cushion arranged on the movable frame, wherein when the sofa bed is used, the movable frame retracts to the upper end of the underframe, the cushion is positioned above the underframe, and the backrest is arranged to incline relative to the underframe, so that the sofa is formed for use; or the movable frame extends out of the front end of the bottom frame to be used as an extension of the bottom frame, the backrest is put down and placed at the upper end of the bottom frame, and the backrest is in butt joint with the seat cushion at the moment to form the bed for use.

In the sofa bed with the structure, in order to enable the backrest to rotate relative to the bottom frame, but the backrest cannot rebound due to the fact that the upper end of the bottom frame is placed when the backrest is put down, and the rotation angle of the backrest is large, the conventional angle-adjustable sofa hinge is not applicable, sofa bed manufacturers connect the backrest with the bottom frame by using the hinge, but the backrest can lean against a wall to support the backrest when the sofa bed is used as a sofa due to the fact that the hinge has no supporting function, and therefore the using position of the sofa bed is limited, and the sofa bed is inconvenient to use.

In addition, chinese patent No. ZL 202120367435.5's utility model discloses a sofa bed structure, including cushion, cushion and connecting piece, the connecting piece is used for connecting cushion and cushion to make sofa bed become the sofa state, the connecting piece includes upper end and lower tip, upper end and lower tip become an contained angle, the upper end is connected with the cushion, the tip includes two constant head tanks of taking the open-ended and at least one lockhole down, the opening of two constant head tanks is located respectively the side and the base of tip down, the constant head tank grafting cooperation in the reference column that sets up on the cushion is in order to prop up during the cushion, the lockhole just is counterpointed in the locating hole that sets up on the cushion, through the locking part locking the lockhole with the locating hole, make lower tip with cushion fixed connection. The positioning grooves are arranged on the connecting pieces, and the positioning grooves and the positioning columns are mutually spliced and aligned, so that the back cushion and the seat cushion are kept in a stable state, and then the locking holes are locked. The sofa bed structure has the following defects: the connecting piece assembly structure is very loaded down with trivial details, and when sofa bed and sofa exchanged, needs the locking part locking lockhole and locating hole, still needs constant head tank and reference column to peg graft each other, and it is very inconvenient to operate.

The size of the backrest/cushion of the two sofa beds is fixed, so that the width of the sofa bed is not large enough to meet the use requirement after the backrest/cushion is laid down.

In view of this, the present inventors propose the following.

The utility model has the following contents:

an object of the utility model is to overcome the not enough of prior art, provide a sofa bed is folded to back and inserted sheet hinge assembly who uses thereof.

In order to solve the technical problem, the utility model discloses a following first technical scheme: the backrest folding sofa bed comprises an underframe, a backrest, a cushion and armrests, wherein the armrests are arranged on two sides of the underframe, the backrest is arranged on the rear side of the underframe through an inserting sheet hinge assembly, the cushion is placed on the underframe, the inserting sheet hinge assembly comprises an inserting sleeve fixed on the rear side of the underframe, an inserting sheet inserted and fixed in the inserting sleeve from top to bottom and a supporting plate hinged with the upper end of the inserting sheet, the supporting plate and the backrest are fixed to form a support for the rear end face of the backrest, the cushion is arranged on a telescopic supporting frame, and the telescopic supporting frame can be retractably placed on the underframe to form a sofa state; after the telescopic support frame is stretched, the end part of the telescopic support frame is abutted against the front end of the underframe, and the backrest is forwards rotated through the support plate relative to the inserting sheet to abut against the upper end surface of the underframe and/or the telescopic support frame so as to form a sofa bed state.

Furthermore, in the above technical solution, the backrest includes a first back cushion and a second back cushion which are mutually overlapped and can be opened relatively, the lower end of the back of the first back cushion is fixedly connected with the support plate, the back of the first back cushion is butted with the back of the second back cushion, and the upper end of the first back cushion is hinged to the back of the second back cushion, after the first back cushion and the second back cushion are opened and laid down, the back of the first back cushion abuts against the upper end of the chassis, and the back of the second back cushion abuts against the upper end of the stretched telescopic support frame.

Further, in the above technical solution, the insert pieces are in a trapezoid shape with a large top and a small bottom; the plug bush is provided with a trapezoid slot with a large upper part and a small lower part, and the insertion piece is inserted and fixed in the trapezoid slot.

Furthermore, in the above technical solution, the plug bush includes a main body portion, a first limiting piece and a second limiting piece respectively formed by bending from outside to inside along two sides of the main body portion, and a third limiting piece formed by bending from outside to inside along a lower end of the main body portion, and the trapezoidal slot is formed between the first limiting piece and the main body portion, the second limiting piece, and the third limiting piece and the main body portion.

Further, among the above-mentioned technical scheme, the backup pad middle part is fixed with the axle sleeve, and this inserted sheet upper end is provided with a breach and stretches over in the axis body of breach, and this axis body wears to locate this axle sleeve hole to the axle sleeve is rotatory relatively, and this axle sleeve is arranged in the breach.

Furthermore, among the above technical scheme, telescopic support frame is including scalable slip and bracing piece and the support frame that the cross-section all is the rectangle, and this support frame is provided with a plurality of sliding sleeves including the first body of rod and set up in this first body of rod front end and be the first supporting legs of vertically with the first body of rod, this upper end of the support bar, but first body of rod rear end is worn to locate in this sliding sleeve to sliding sleeve slides relatively.

Further, in the above technical solution, a blocking piece protruding downward is formed at the rear end of the supporting rod; a sinking groove which is sunken downwards and is used for accommodating the supporting rod is arranged at the upper edge of the front end of the underframe, and the height of the sinking groove is equal to the thickness of the supporting rod; the front end of the first supporting leg is also provided with a front baffle which is arranged at the front end of the chassis.

In order to solve the technical problem, the utility model adopts the following second technical scheme: the inserting sheet hinge assembly comprises an inserting sleeve, an inserting sheet and a supporting plate, wherein the inserting sheet is inserted and fixed in the inserting sleeve from top to bottom, the supporting plate is hinged with the upper end of the inserting sheet, and the inserting sheet is in a trapezoid shape with a large upper part and a small lower part; the plug bush is provided with a trapezoid slot with a large upper part and a small lower part, and the insertion piece is inserted and fixed in the trapezoid slot.

After the technical scheme is adopted, compared with the prior art, the utility model has following beneficial effect:

1. relative first sofa bed in the background art, the utility model discloses an inserted sheet hinge assembly replaces hinge connection back and chassis, and this inserted sheet hinge assembly's backup pad can form the support to the back to prevent relative chassis backward to the bottom under this back, so that the utility model relates to a sofa uses, and it need not to lean on the wall to form the support, so that can use at the optional position, it is more convenient to use. In addition, the backrest can rotate through the inserting sheet hinge assembly and lean against the bottom frame removed from the seat cushion, so that a sofa bed is formed at the later stage, and the requirement of converting the sofa into the sofa bed for use is met.

2. Compared with the second sofa bed in the background art, the utility model adopts the insert sheet hinge assembly to replace the connecting piece to connect the backrest and the bottom frame, so that the operation steps of locking the lock hole and the positioning hole by the locking piece and mutually inserting the positioning groove and the positioning column are not needed when the sofa bed and the sofa are exchanged, and the support plate of the insert sheet hinge assembly can support the backrest when the sofa is in a sofa state, so as to prevent the lower part of the backrest from going backwards downwards relative to the bottom frame; when needs convert sofa bed into and use, directly with this back through the relative inserted sheet forward rotation of backup pad and lean on to chassis and/or telescopic bracket's up end, make the cushion butt joint on back and the telescopic bracket to form sofa bed, its operation is very convenient.

Description of the drawings:

FIG. 1 is a structural diagram of the sofa bed of the present invention;

FIG. 2 is a structural diagram of the present invention;

FIG. 3 is a perspective view of an insert hinge assembly of the present invention;

FIG. 4 is a perspective view of the middle plug bush of the present invention;

FIG. 5 is an assembly view of the insert and the support plate of the present invention;

FIG. 6 is an assembly view of the telescopic support frame of the present invention;

fig. 7 is an assembly view of the middle base frame, back rest, arm rests and insert hinge assembly of the present invention;

fig. 8 is an assembly view of the backrest and insert hinge assembly of the present invention;

fig. 9 is an assembly view of the middle cushion and the telescopic support frame of the present invention.

The specific implementation mode is as follows:

the present invention will be further described with reference to the following specific embodiments and accompanying drawings.

See fig. 1-9, for a sofa bed with a foldable backrest, which comprises a bottom frame 1, a backrest 2, a seat cushion 3 and armrests 4, wherein the armrests 4 are disposed on two sides of the bottom frame 1, the seat cushion 3 is disposed on the bottom frame 1, the seat cushion 3 can be moved away from the bottom frame 1 to form a sofa bed at a later stage, the backrest 2 is disposed on the rear side of the bottom frame 1 through an insert sheet hinge assembly 5, the backrest 2 can be supported and positioned on the rear side of the bottom frame 1 through the insert sheet hinge assembly 5, that is, after the backrest 2 is obliquely unfolded relative to the bottom frame 1, the insert sheet hinge assembly 5 can support the backrest 2 to prevent the backrest 2 from falling backwards relative to the bottom frame 1, so that the sofa bed can be used as a sofa. In addition, the backrest 2 can rotate by the inserting sheet hinge assembly 5 to abut against the bottom frame 1 after being moved away from the seat cushion 3, so that the sofa bed is formed at a later stage.

Specifically, the inserting sheet hinge assembly 5 includes an inserting sleeve 51 fixed at the rear side of the base frame 1, an inserting sheet 52 inserted and fixed in the inserting sleeve 51 from top to bottom, and a supporting plate 53 hinged to the upper end of the inserting sheet 52, the supporting plate 53 is fixed to the backrest 2 to support the rear end face of the backrest 2, and meanwhile, the backrest 2 can rotate relative to the inserting sheet 52 through the supporting plate 53 to turn the backrest 2 forward relative to the base frame 1 to be laid on the base frame 1.

The cushion 3 is arranged on a telescopic support frame 6, and the telescopic support frame 6 can be retractably placed on the underframe 1 so as to form a sofa state at a later stage.

When the utility model is used as a sofa, the backrest 2 is obliquely unfolded relative to the bottom frame 1, and the insert sheet hinge assembly 5 supports the backrest 2 through the support plate 53 so as to prevent the backrest 2 from falling backwards relative to the bottom frame 1; meanwhile, the telescopic support frame 6 can be retractably placed on the base frame 1, so that the cushion 3 is placed on the base frame 1, thereby forming a sofa state and being used as a sofa. When the utility model discloses when using as sofa bed, through with the tensile back of

telescopic support frame

6, 6 tip of this telescopic support frame are taken and are leaned on at chassis 1 front end to rotate forward this back 2 through the relative inserted sheet 52 of backup pad 53 and lean on to chassis 1 and/or telescopic support frame 6's up end, make back 2 and the cushion 3 butt joint on the telescopic support frame 6, in order to form sofa bed.

The utility model provides an inserted sheet hinge assembly 5 simple structure, simple to operate to can realize forming the support to back 2, still can make back 2 rotate forward and lean on the up end that leans on to chassis 1 and/or telescopic support frame 6, so that form the sofa bed and use.

Because 6 tip of telescopic support frame are to lapping at the chassis 1 front end, it is direct does not have fixed connection relation, and it is convenient for dismantle this cushion 3 relative chassis 1 to the packing is the product that the volume is littleer, so that the transportation.

Relative first sofa bed in the background art, the utility model discloses an inserted sheet hinge assembly 5 replaces hinge connection back and chassis, and the backup pad 53 of this inserted sheet hinge assembly 5 can form the support to back 2 to prevent to go backward to down relative chassis 1 under this back 2, so that the utility model relates to a sofa uses, and it need not to lean on the wall to form the support, so that can use at the optional position, and it is more convenient to use. In addition, the backrest 2 can rotate through the inserting sheet hinge assembly 5 and is abutted against the bottom frame 1 after being moved away from the seat cushion 3, so that a sofa bed is formed at a later stage, and the requirement of converting the sofa into the sofa bed for use is met. Compared with the second sofa bed in the background art, the utility model adopts the insert sheet hinge assembly 5 to replace the connecting piece to connect the backrest and the bottom frame, so that the operation steps of locking the locking hole and the positioning hole by the locking piece and mutually inserting the positioning groove and the positioning post are not needed when the sofa bed and the sofa are exchanged, and the support plate 53 of the insert sheet hinge assembly 5 can support the backrest 2 in the sofa state so as to prevent the backrest 2 from going backwards and downwards relative to the bottom frame 1; when the sofa bed is required to be converted for use, the backrest 2 is directly rotated forwards relative to the inserting pieces 52 through the supporting plate 53 and is abutted to the upper end face of the underframe 1 and/or the telescopic support frame 6, so that the backrest 2 is abutted with the seat cushion 3 on the telescopic support frame 6 to form the sofa bed, and the sofa bed is extremely convenient to operate.

The insert hinge assembly 5 is further described below.

The inserting sheet 52 in the inserting sheet hinge assembly 5 is inserted and fixed in the inserting sleeve 51 from top to bottom, the upper end of the inserting sheet 52 is hinged in the middle of the supporting plate 53, the inserting sheet 52 and the inserting sleeve 51 form a quick-release structure, and during assembly, the inserting sheet 52 can be directly inserted and fixed in the inserting sleeve 51 from top to bottom, so that stable assembly is realized, and the operation is more rapid and convenient. And at the later stage, the inserting sheet 52 can be pulled out relative to the inserting sleeve 51, so that the inserting sheet 52 is separated from the inserting sleeve 51, and the aim of disassembly is fulfilled.

The inserting pieces 52 are in a trapezoid shape with a large upper part and a small lower part; the plug bush 51 is provided with a trapezoid slot 510 with a large upper part and a small lower part, the plug-in sheet 52 is inserted and fixed in the trapezoid slot 510, so that after the plug-in sheet 52 is inserted in the plug bush 51, stable assembly can be formed, and the deeper the plug-in sheet 52 is inserted, the tighter the fixing between the plug-in sheet 52 and the plug bush 51 is.

The inserting pieces 52 and the inserting sleeves 51 are formed by bending metal plates, and the structure is stable. The support plate 53 is a metal plate.

The plug bush 51 includes a main body 511, a first limiting piece 512 and a second limiting piece 513 formed by bending from outside to inside along two sides of the main body 511, and a third limiting piece 514 formed by bending from outside to inside along a lower end of the main body 511, wherein the trapezoidal slot 510 is formed between the first limiting piece 512 and the main body 511, the second limiting piece 513, and the third limiting piece 514 and the main body 511, and the structure is very stable.

The middle part of the support plate 53 is fixed with a shaft sleeve 531, the upper end of the inserting piece 52 is provided with a notch 521 and a shaft body 522 crossing the notch 521, the shaft body 522 penetrates through an inner hole of the shaft sleeve 531 and can rotate relative to the shaft sleeve 531, and the shaft sleeve 531 is arranged in the notch 521, so that the inserting piece 52 avoids the shaft sleeve 531 through the notch 521 when the shaft body 522 rotates relative to the shaft sleeve 531, thereby ensuring that the inserting piece 52 can rotate stably and without obstacles relative to the support plate 53, and the hinge assembly structure between the inserting piece 52 and the support plate 53 is simple and stable in structure.

In order to increase the area of the sofa bed and reduce the volume when the sofa is converted into the sofa for use, the following design is made: the backrest 2 comprises a first back cushion 21 and a second back cushion 22 which are mutually overlapped and can be opened relatively, the lower end of the back of the first back cushion 21 is fixedly connected with the supporting plate 53, the back of the first back cushion 21 is butted with the back of the second back cushion 22, the upper ends of the first back cushion 21 and the second back cushion 22 are hinged, after the first back cushion 21 and the second back cushion 22 are opened and laid down, the back of the first back cushion 21 abuts against the upper end of the underframe 1, and the back of the second back cushion 22 abuts against the upper end of the stretched telescopic supporting frame 6. When the sofa bed is used, the first back cushion 21 and the second back cushion 22 are opened relatively to increase the area of the backrest, and after the first back cushion 21 and the second back cushion 22 are laid down, the back surface of the first back cushion 21 abuts against the upper end of the underframe 1, and the back surface of the second back cushion 22 abuts against the upper end of the stretched telescopic support frame 6, so that the area of the sofa bed can be greatly increased, and the sofa bed is more convenient to use. In addition, when converted to sofa use, the first and

second cushions

21 and 22 are folded over each other to form a thickened backrest, and the backrest is supported by the tab hinge assembly 5, thereby being stably supported on the base frame and being usable as a small sofa, particularly for small house type houses.

The first cushion 21 and the second cushion 22 are hinged by a hinge 20 so that the first cushion 21 and the second cushion 22 can be unfolded and folded.

In addition, a pull rope 221 is provided at the lower end of the back surface of the second bolster 22. The user can pull the pulling rope 221 to open the second cushion 22 relative to the first cushion 21 and slowly pull the first cushion 21 and the second cushion 22 down to abut against the upper end of the underframe 1 and the upper end of the stretched telescopic support frame 6, so that the operation is more convenient.

The telescopic support frame 6 comprises a support rod 61 and a support frame body 62, wherein the cross section of the support rod 61 is rectangular, the support frame body 62 comprises a first rod body 621 and a first support leg 622 which is arranged at the front end of the first rod body 621 and is perpendicular to the first rod body 621, a plurality of sliding sleeves 612 are arranged at the upper end of the support rod 61, the rear end of the first rod body 621 penetrates through the sliding sleeves 612, the sliding sleeves 612 can slide relatively, and the assembly structure is very simple.

A blocking piece 611 protruding downwards is formed at the rear end of the supporting rod 61; a sinking groove 11 which is sunken downwards and is used for accommodating the supporting rod 61 is formed in the upper edge of the front end of the underframe 1, and the height of the sinking groove 11 is equal to the thickness of the supporting rod 61; so that after the supporting rod 61 is stretched relative to the supporting frame 62, the upper end surface of the supporting rod 61 is flush with the upper end surface of the bottom frame 1, thereby being convenient for better supporting a laid backrest and avoiding the backrest from shaking.

The front end of the first supporting leg 622 is further provided with a front baffle 63, and the front baffle 63 is blocked at the front end of the chassis 1, so that foreign matters with large volume can be prevented from entering the chassis 1, and meanwhile, the attractiveness of the product can be ensured.

The supporting rod 61 and the supporting frame body 62 are respectively provided with a first screw hole 610 and a second screw hole 620 which correspond to each other, when the supporting rod 61 and the supporting frame body 62 are stretched to a predetermined position, the first screw hole 610 and the second screw hole 620 are aligned, and screws are spirally inserted into the first screw hole 610 and the second screw hole 620 so as to lock the supporting rod 61 and the supporting frame body 62, thereby ensuring that a stable support is formed.

To sum up, relative the first sofa bed among the background art, the utility model discloses an inserted sheet hinge assembly 5 replaces hinge connection back and chassis, and the backup pad 53 of this inserted sheet hinge assembly 5 can form the support to back 2 to prevent to go down backward relative chassis 1 under this back 2, so that the utility model relates to a sofa uses, and it need not to lean on the wall to form the support, so that can use at the optional position, and it is more convenient to use. In addition, the backrest 2 can rotate through the inserting sheet hinge assembly 5 and abut against the bottom frame 1 after being moved away from the seat cushion 3, so that a sofa bed is formed at a later stage, and the requirement of converting the sofa into the sofa bed for use is met. Compared with the second sofa bed in the background art, the utility model adopts the insert sheet hinge assembly 5 to replace the connecting piece to connect the backrest and the bottom frame, so that the operation steps of locking the locking hole and the positioning hole by the locking piece and mutually inserting the positioning groove and the positioning post are not needed when the sofa bed and the sofa are exchanged, and the support plate 53 of the insert sheet hinge assembly 5 can support the backrest 2 in the sofa state so as to prevent the backrest 2 from going backwards and downwards relative to the bottom frame 1; when the sofa bed needs to be converted into a sofa bed for use, the backrest 2 is directly abutted to the upper end surface of the underframe 1 and/or the telescopic support frame 6 by rotating the support plate 53 forwards relative to the inserting sheet 52, so that the backrest 2 is abutted to the seat cushion 3 on the telescopic support frame 6 to form the sofa bed, and the sofa bed is very convenient to operate.

Of course, the above description is only an exemplary embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes and modifications made by the constructions, features, and principles of the present invention in accordance with the claims of the present invention are intended to be included in the scope of the present invention.

Claims

1. The utility model provides a sofa bed is folded to back, its includes chassis (1), back (2), cushion (3) and handrail (4), and this handrail (4) set up in chassis (1) both sides, and this back (2) set up in chassis (1) rear side through inserted sheet hinge assembly (5), and its characterized in that is placed on chassis (1) in this cushion (3):

the insert hinge assembly (5) comprises an insert (51) fixed at the rear side of the underframe (1), an insert (52) inserted and fixed in the insert (51) from top to bottom and a support plate (53) hinged with the upper end of the insert (52), the support plate (53) is fixed with the backrest (2) to support the rear end face of the backrest (2), the seat cushion (3) is arranged on a telescopic support frame (6), and the telescopic support frame (6) can be retractably arranged on the underframe (1) to form a sofa state; after the telescopic support frame (6) is stretched, the end part of the telescopic support frame (6) is abutted against the front end of the underframe (1), and the backrest (2) is rotated forwards relative to the inserting piece (52) through the support plate (53) and abutted against the upper end surface of the underframe (1) and/or the telescopic support frame (6) to form a sofa bed state.

2. A back rest folding sofa bed as claimed in claim 1, wherein: the backrest (2) comprises a first back cushion (21) and a second back cushion (22) which are mutually oppositely overlapped and can be relatively opened, the lower end of the back face of the first back cushion (21) is fixedly connected with a supporting plate (53), the back face of the first back cushion (21) is butted with the back face of the second back cushion (22), the upper ends of the first back cushion and the second back cushion are hinged, after the first back cushion (21) and the second back cushion (22) are opened and laid down, the back face of the first back cushion (21) abuts against the upper end of the chassis (1), and the back face of the second back cushion (22) abuts against the upper end of the stretched telescopic supporting frame (6).

3. A back rest folding sofa bed as claimed in claim 1, wherein: the inserting sheet (52) is in a trapezoid shape with a large upper part and a small lower part; the plug bush (51) is provided with a trapezoid slot (510) with a large upper part and a small lower part, and the plug-in sheet (52) is inserted and fixed in the trapezoid slot (510).

4. A back rest folding sofa bed according to claim 3, wherein: the plug bush (51) comprises a main body part (511), a first limiting sheet (512) and a second limiting sheet (513) which are respectively formed by bending the two sides of the main body part (511) from outside to inside, and a third limiting sheet (514) which is formed by bending the lower end of the main body part (511) from outside to inside, wherein a trapezoidal slot (510) is formed between the first limiting sheet (512) and the second limiting sheet (513) and between the third limiting sheet (514) and the main body part (511).

5. A back rest folding sofa bed as claimed in claim 3, wherein: the middle of the supporting plate (53) is fixed with a shaft sleeve (531), the upper end of the inserting piece (52) is provided with a notch (521) and a shaft body (522) stretching over the notch (521), the shaft body (522) penetrates through an inner hole of the shaft sleeve (531) and can rotate relative to the shaft sleeve (531), and the shaft sleeve (531) is arranged in the notch (521).

6. A back rest folding sofa bed as claimed in any one of claims 1 to 5, wherein: the telescopic support frame (6) comprises a support rod (61) and a support frame body (62) which can slide in a telescopic manner and have rectangular cross sections, wherein the support frame body (62) comprises a first rod body (621) and a first support leg (622) which is arranged at the front end of the first rod body (621) and is vertical to the first rod body (621), a plurality of sliding sleeves (612) are arranged at the upper end of the support rod (61), the rear end of the first rod body (621) penetrates through the sliding sleeves (612), and the sliding sleeves (612) can slide relatively.

7. A back rest folding sofa bed as claimed in claim 6, wherein: a blocking piece (611) protruding downwards is formed at the rear end of the supporting rod (61); a sunken groove (11) which is sunken downwards and used for accommodating the supporting rod (61) is formed in the upper edge of the front end of the bottom frame (1), and the height of the sunken groove (11) is equal to the thickness of the supporting rod (61); the front end of the first supporting leg (622) is also provided with a front baffle (63), and the front baffle (63) is blocked at the front end of the chassis (1).

8. The inserting sheet hinge assembly is characterized in that the inserting sheet hinge assembly (5) comprises an inserting sleeve (51), an inserting sheet (52) which is inserted and fixed in the inserting sleeve (51) from top to bottom and a supporting plate (53) which is hinged with the upper end of the inserting sheet (52), wherein the inserting sheet (52) is in a trapezoid shape with a large top and a small bottom; the plug bush (51) is provided with a trapezoid slot (510) with a large upper part and a small lower part, and the plug-in sheet (52) is inserted and fixed in the trapezoid slot (510).

9. The tab hinge assembly of claim 8, wherein: the plug bush (51) comprises a main body part (511), a first limiting sheet (512) and a second limiting sheet (513) which are respectively formed by bending the two sides of the main body part (511) from outside to inside, and a third limiting sheet (514) which is formed by bending the lower end of the main body part (511) from outside to inside, wherein a trapezoidal slot (510) is formed between the first limiting sheet (512) and the second limiting sheet (513) and between the third limiting sheet (514) and the main body part (511).

10. The tab hinge assembly of claim 8 wherein: the middle of the supporting plate (53) is fixed with a shaft sleeve (531), the upper end of the inserting piece (52) is provided with a notch (521) and a shaft body (522) stretching over the notch (521), the shaft body (522) penetrates through an inner hole of the shaft sleeve (531) and can rotate relative to the shaft sleeve (531), and the shaft sleeve (531) is arranged in the notch (521).