SOFA BED

Abstract

A sofa bed includes a seat portion, a backrest portion, a seat portion connecting rod, a backrest portion connecting rod, and two armrest frames. The seat portion connecting rod and the backrest portion connecting rod are connected at a locking mechanism and are pivotable relative to each other and lockable relative to each other. The two armrest frames are provided at both ends of the seat portion and the backrest portion in the longitudinal direction. Each of the armrest frames is provided with a sliding groove that opens toward the backrest portion and the seat portion and partially extends in the transverse direction. A rear end of the sliding groove is positioned lower than a front end of the sliding groove. An angle formed between the seat portion and the backrest portion can be locked to improve the reliability of the operation. A switching operation is quickly and easily achieved by allowing ta pin to slide in the sliding groove in an extension direction having a transverse component and a vertical component

Description

PRIORITY CLAIM

This application claims the benefit of Chinese Patent Application No. 202110064263.9, filed Jan. 18, 2021, which is incorporated herein by reference.

FIELD

The present disclosure relates to the design of furniture, and specifically to a sofa bed.

BACKGROUND

With incremental improvements of people's material well-being life, the need of the consumer for household furniture presents a trend of diversification, wherein sofa beds already become a type of popular furniture products. The conventional sofa beds have some drawbacks, such as for example, the switching of the conventional sofa beds between two states is not smooth enough, so that it is usually difficult for an operator with less power to complete the switching individually; the conventional sofa beds might not be stable enough in the sofa state, and an angle between the seat and the backrest might be changed, which affects the degree of comfort; and the folding manner of the conventional sofa beds is single and thus cannot satisfy the user's various demands.

Therefore, it is desirable to provide a sofa bed to at least partially solve the above problems.

SUMMARY

A main object of the present invention is to provide a sofa bed which is easily switchable between two in-use positions and easy to operate. Furthermore, in a predetermined switching procedure and a predetermine use procedure, an angle between a seat portion and a backrest portion can be locked to improve the reliability of the operation. In the switching operation, by allowing a pin to slide in a sliding groove in an extension direction having a transverse component and a vertical component, the burden of an user in operation can be lightened, and the switching operation can be achieved quickly and easily. Furthermore, the sofa bed may be provided with a plurality of detachable elastic modules which are simple to mount and convenient to operate. Thus, the user may manually mount them to obtain a sofa bed having a better degree of comfort.

According to an aspect of the present invention, there is provided a sofa bed, comprising:

a main body frame comprising a seat portion and a backrest portion arranged adjacent to each other, the seat portion and the backrest portion being configured to be folded or unfolded about a locking mechanism, so that the main body frame is changed between a bed configuration and a sofa configuration; and

an armrest frame respectively disposed on both sides of the main body frame in a longitudinal direction, and connected to the main body frame via the locking mechanism, wherein each of the armrest frames is formed with a slideway through which the movement of the locking mechanism is guided,

wherein, when the backrest portion and the seat portion are pivotal relative to each other about the locking mechanism, the sofa bed is configured to lock the backrest portion relative to the seat portion at a predetermined angle, and allow the locking mechanism to drive the main body frame to displace while the locking mechanism being guided by the slideway in a locked state.

According to a preferable embodiment of the present invention, the locking mechanism comprises:

a seat portion connecting rod attached to and extending along a transverse side edge of the seat portion;

a backrest portion connecting rod attached to a transverse side edge of the backrest portion on the same side as the transverse side edge of the seat portion and extending along the transverse side edge of the backrest portion; and

a pivot shaft connecting the seat portion connecting rod with the backrest portion connecting rod so that the backrest portion and the seat portion can pivot relative to each other.

According to another preferable embodiment of the present invention, the main body frame is configured to release the locking between the seat portion connecting rod and the backrest portion connecting rod when the seat portion arranged in the locked stated is operated to pivot towards the backrest portion.

According to a further preferable embodiment of the present invention, one of the seat portion connecting rod and the backrest portion connecting rod is provided with a ratchet, and the other of the seat portion connecting rod and the backrest portion connecting rod is provided with a pawl, wherein the ratchet and the pawl engage with each other so that the backrest portion is locked at a predetermined angle with respect to the seat portion.

According to a further preferable embodiment of the present invention, an outer edge of the ratchet is provided with a recessed portion that is recessed inward in a radial direction of the ratchet, and the pawl is provided with a protruding portion corresponding to the recessed portion, wherein the protruding portion is configured to enable the protruding portion to engage the recessed portion when the backrest portion and the seat portion form the predetermined angle, thereby locking the backrest portion and the seat portion.

According to a further preferable embodiment of the present invention, both the seat portion and the backrest portion are formed as a rectangular structure.

According to a further preferable embodiment of the present invention, a side edge of the seat portion extending in the longitudinal direction and a side edge of the backrest portion extending in the longitudinal direction are arranged adjacent to each other.

According to a further preferable embodiment of the present invention, the main body frame is configured such that the backrest portion can be locked at a plurality of different predetermined angles relative to the seat portion.

According to a further preferable embodiment of the present invention, the main body frame further comprises a driven beam, one end of the driven beam is pivotally connected to the armrest frame, and the other end of the driven beam is pivotally connected to the backrest portion.

According to a further preferable embodiment of the present invention, the armrest frame comprises a substantially -shaped armrest frame body (referred to as a “channel shape”) and a reinforcing transverse beam connected between two legs of the armrest frame body, and the slideway is formed on the reinforcing transverse beam.

According to a further preferable embodiment of the present invention, the locking mechanism is provided with a pin extending toward the outside of the main body frame, and the slideway is a sliding groove formed on the reinforcing transverse beam, one end of the slideway is positioned higher than the other end of the slideway, and the one end is open toward an upper edge of the armrest frame so as to receive the pin of the locking mechanism.

According to another preferable embodiment of the present invention, the reinforcing transverse beam is provided with a sliding rod, and the locking mechanism is provided with a sliding sleeve which is configured to be sleeved on the sliding rod and slide along the sliding rod.

According to a further preferable embodiment of the present invention, a sliding rod is provided under the reinforcing transverse beam, and the sliding rod and a lower edge of the reinforcing transverse beam jointly define the sliding groove.

According to a further preferable embodiment of the present invention, a cross section of the reinforcing transverse beam is in a shape of , and an outer end of the pin is provided with a protrusion that can mating with the shape.

According to a further preferable embodiment of the present invention, the sofa bed comprises a bottom supporting structure that is disposed under the backrest portion and the seat portion and is fixedly connected to the two armrest frames.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference may be made to preferred embodiments shown in the figures to enable better understanding of the above and other objects, features, advantages and functions of the present invention. The same or like reference numerals in the figures denote the same or like parts. Those skilled in the art should appreciate that the figures are intended to schematically illustrate the preferred embodiments of the present invention, and not intended to limit the scope of the present invention, and all parts shown in the figures are not drawn to scale.

FIG. 1 is a perspective schematic view of a main body frame of a sofa bed according to a preferred embodiment of the present invention when it is arranged in a bed state;

FIG. 2 is a side view of the sofa bed shown in FIG. 1;

FIG. 3 is a perspective schematic view of the main body frame of FIG. 1 in a sofa state;

FIG. 4 is a side view of the sofa bed shown in FIG. 3;

FIG. 5 is an exploded schematic view of a junction of a seat portion and a backrest portion in the present embodiment;

FIG. 6A-FIG. 6F are side views of the main body frame according to the preferred embodiment, which sequentially show a process in which the sofa transitions from a first in-use state to a second in-use state, and then return back to the first in-use state;

FIG. 7A shows a schematic diagram of a sliding groove in the preferred embodiment;

FIG. 7B-FIG. 7D are alternative implementations of the sliding groove shown in FIG. 7A;

FIG. 7E is a cross-sectional view taken along line C-C indicated in FIG. 7D, wherein hatching lines are omitted in FIG. 7E for a clearer illustration purpose:

FIG. 8 is a schematic diagram of an elastic module of a sofa bed according to a preferred embodiment of the present invention;

FIG. 9-FIG. 11 are schematic diagrams of a process in which an elastic module is mounted to the main body frame;

FIG. 12 is a schematic diagram after elastic modules are mounted on the main body frame;

FIG. 13 and FIG. 14 are respective schematic diagrams showing shapes of a finished product of the sofa bed.

DETAILED DESCRIPTION OF EMBODIMENTS

Specific embodiments of the present prevention will now be described in detail with reference to the figures. What are described here are only preferred embodiments according to the present invention. Those skilled in the art can implement other embodiments of the present invention on the basis of the preferred embodiments, and said other embodiments also fall within the scope of the present invention.

The invention provides a sofa bed. FIG. 1-FIG. 7E show at least partial structures according to some preferred embodiments of the present invention. First, it will be appreciated that “transverse direction” and “longitudinal direction” mentioned in the present invention refer to absolute directions, and respectively two directions perpendicular to each other in a horizontal plane, wherein the transverse direction is shown by X in the figures, and the longitudinal direction is shown by Y in the figures; “widthwise direction” and “lengthwise direction” mentioned in the present invention refer to relative directions relative to a rectangle formed by a seat portion and a backrest portion, but the lengthwise direction always coincides with the longitudinal direction Y, the widthwise direction coincides with the transverse direction X only when the seat portion and/or backrest portion are placed horizontally. A height direction mentioned in the context is an absolute vertical direction and shown by Z in the figures.

FIG. 1-FIG. 14 show some preferred embodiments of the present invention.

Referring to FIG. 1 through FIG. 4, a sofa bed according to a preferred embodiment of the present application comprising a main body frame 100 which includes a seat portion 4, a backrest portion 3, a seat portion connecting rod 41, a backrest portion connecting rod 31, and two armrest frames 2. The seat portion 4 and the backrest portion 3 are both formed as a rectangular structure, which may be a rectangular frame structure or a rectangular plate-like structure. A longitudinal edge of the seat portion 4 and a longitudinal edge of the backrest portion 3 are butted together.

The seat portion connecting rod 41 is fixed on a widthwise edge of the seat portion 4, the backrest portion connecting rod 31 is fixed on a widthwise edge of the backrest portion 3, and the seat portion connecting rod 41 and the backrest connecting rod 31 are connected together in a way that they are pivotable relative to each other. When the seat portion connecting rod 41 and the backrest portion connecting rod 31 pivot relative to each other, an angle formed therebetween increases or decreases. It will be appreciated that the “angle” mentioned in the present invention refers to an angle less than or equal to 180°.

The two armrest frames 2 are provided at both ends of the seat portion 4 and the backrest portion 3 in the longitudinal direction, and each of the armrest frames 2 is provided with a slideway that opens toward the backrest portion 3 and the seat portion 4 and partially extends in the transverse direction. In the present embodiment, the slideway is a sliding groove 211, and a rear end 211b of the sliding groove 211 is positioned lower than a front end 211a of the sliding groove 211.

The exploded schematic view of the pivotal connection of the seat portion 4 and the backrest portion 3 is shown in FIG. 5. Referring to FIG. 5, the seat portion connecting rod 41 and the backrest portion connecting rod 31 are engaged with each other at a locking mechanism 34, and the locking mechanism 34 has a pin 341 protruding from a side facing the armrest. The front end 211a of the sliding groove 211 is provided with an upward opening, so that the pin 341 can enter into the sliding groove 211 from the front end 211a of the sliding groove 211 and slide in the sliding groove 211. A special-shaped gear and a gear matching claw are provided at the locking mechanism 34, and they are respectively disposed on the seat portion connecting rod 41 and the backrest portion connecting rod 31. The special-shaped gear is for example a ratchet wheel 342, wherein the edge of the ratchet 342 is provided with a recessed portion that is recessed in a radial direction of the ratchet 342. The gear matching pawl is provided with a protruding portion that mates with the recessed portion. The recessed portion and the protruding portion are positioned such that when the backrest portion 3 and the seat portion 4 are located at a predetermined obtuse angle, the protruding portion is embedded or inserted in the recessed portion to achieve locking. The seat portion 4 is provided with a seat portion insertion sleeve 42 for accommodating the seat portion connecting rod 41, and the backrest portion 3 is provided with a backrest portion insertion sleeve 32 for accommodating the backrest portion connecting rod 31.

Furthermore, each armrest frame 2 includes an armrest frame body 22 and a reinforcing transverse beam 21, wherein the sliding groove 211 is disposed on the reinforcing transverse beam 21, and an extension direction of the reinforcing transverse beam 21 coincides with that of the sliding groove 21, i.e., the rear end 211b of the reinforcing transverse beam 21 is also positioned lower than the front end 211a of the reinforcing transverse beam 21. The armrest frame body 22 further includes two upright columns extending in the vertical direction and a body transverse beam connected at the tops of the two upright columns. The reinforcing transverse beam is connected to the middle of the two upright columns and is parallel to the body transverse beam.

In addition to the armrest frame 2, the supporting and fixing structure of the sofa bed further includes a bottom supporting structure 24 which is disposed under the backrest portion 3 and the seat portion 4 and is fixedly connected to the two armrest frames 2. The bottom supporting structure 24 includes for example a bottom supporting structure longitudinal beam, a bottom supporting structure transverse beam 23 and legs 25. The sofa bed further includes a driven beam 26, one end of which is pivotally connected to the armrest frame 2, and the other end of which is pivotally connected to the backrest portion 3.

FIG. 6A-FIG. 6F show a process in which the main body frame 100 changes from a first in-use position (at which the sofa bed is used as a bed) to a second in-use position (at which the sofa bed is used as a sofa) and then returns back to the first in-used position.

First, referring to FIG. 6A, when the main body frame 100 is located at the first in-use position, the backrest portion 3 and the seat portion 4 are both horizontal, and the angle formed therebetween is a straight angle. The angle formed between the backrest portion connecting rod 31 and the seat portion connecting rod 41 is also substantially a straight angle, and the pivot axis of the locking mechanism 34 is substantially located adjacent to the front end 211a of the sliding groove 211. At this time, the backrest portion connecting rod 31 and the seat portion connecting rod 41 are not locked, thereby allowing the seat portion 4 to be operated to pivot toward a position where the angle between the seat portion 4 and the backrest portion 3 is reduced. The direction of the pivoting is shown by an arrow in FIG. 6A.

When it requires to adjust the main body frame 100 to the second in-use position, the seat portion 4 can be pivoted in the direction shown by the arrow in FIG. 6A, to a position shown in FIG. 6B. At the position shown in FIG. 6B, the pivoting between the backrest portion connecting rod 31 and the seat portion connecting rod 41 is locked. Specifically, for example, the locking mechanism 34 may be provided with a special-shaped ratchet 342 and a special-shaped pawl which have shapes matching to each other. The special-shaped ratchet 342 and the special-shaped pawl are shaped to snap fit together at the position shown in FIG. 6B to prevent the seat portion 4 from further rotating relative to the backrest portion 3. At this time, the angle between the seat portion 4 and the backrest portion 3 is a, which is an obtuse angle. The “predetermined obtuse angle” mentioned in the present invention may be understood as a shown in FIG. 6B.

At this time, the pin 341 at the locking mechanism 34 can enter into the sliding groove 211 from the front end 211a of the sliding groove 211. Then, as shown in FIG. 6C, the seat portion 4 may be pressed down along an arc-shaped arrow, and meanwhile the pin 341 can drive the combination of the backrest portion 3 and the seat portion 4 to slide in a direction indicated by a straight arrow in FIG. 6C. After this operation, the combination of the backrest portion 3 and the seat portion 4 can reach the second in-use position as shown in FIG. 6D.

In the structure shown in FIG. 6B through FIG. 6D, the backrest portion connecting rod 31 and the seat portion connecting rod 41 are locked to each other at the locking mechanism 34, and the angle between the backrest portion 3 and the seat portion 4 is always α.

When it is required to change the main body frame 100 from the second in-use position to the first in-use position, the seat portion 4 can be manually operated to further pivot toward the backrest portion 3 in the direction indicated by the arrow as shown in FIG. 6D. The action for example can make the protruding portion of the pawl disengage from the recessed portion of the ratchet, thereby releasing the locking between the seat portion connecting rod 41 and the backrest portion connecting rod 31.

Referring to FIG. 6E, after the seat portion 4 is pivoted in the direction indicated by arrow A, the locking between the seat portion connecting rod 41 and the backrest portion connecting rod 31 is released. After the unlocking, the pin 341 is slided in the sliding groove 211 toward the front end 211a in the direction indicated by the arrow B, thereby driving the backrest portion 3 and the seat portion 4 to reach the position shown in FIG. 6F, so that the main body frame 100 returns to the first in-use position.

FIG. 7A shows details of the sliding groove 211 in FIG. 1 through FIG. 6F. In the FIG. 7A, the sliding groove 211 is a groove structure formed on the reinforcing transverse beam 21 itself of the armrest frame 2. FIG. 7B through FIG. 7D show some alternative embodiments of FIG. 7A.

In the embodiment shown in FIG. 7B, the reinforcing transverse beam 21a is provided with a sliding rod 212, and a sliding sleeve 341a is fixedly fixed at the locking mechanism of the backrest portion connecting rod and the seat portion connecting rod to engage with and slide on the sliding rod 212.

In the embodiment shown in FIG. 7C, a sliding rod is disposed under the reinforcing transverse beam 21b, the sliding rod and the lower edge of the reinforcing transverse beam 21b jointly define a sliding groove 213, and a pin 341b fixedly disposed at the locking mechanism of the backrest portion connecting rod and the seat portion connecting rod can engage with and slide in the sliding groove 213.

In the embodiment shown in FIG. 7D, the reinforcing transverse beam 21c is a special-shaped beam whose cross section is shown in FIG. 7E. Referring to FIG. 7E, the cross-section of the reinforcing transverse beam 21c is in a shape of , and a pin 341c is fixedly disposed at the locking mechanism of the backrest portion connecting rod and the seat portion connecting rod, wherein a projection having a shape that can mate with the shape is provided at an outer end of the pin 341c, and the projection can be adaptively received in the 1L shaped beam so that the pin 341c can slide along the sliding groove 214 without disengaging from the sliding groove 214. Two stoppers ae provided in the -shaped beam, wherein a front stopper 214b can constitute the front end of the sliding groove 214, and a rear stopper 214a can constitute the rear end of the sliding groove 214.

In addition to the above structure, the sofa bed according to the present invention may further include a plurality of elastic modules. FIG. 8 shows an example of an elastic module. Referring to FIG. 8, each of the elastic modules 200 includes a conical spring 110 and a spring bracket 121 accommodating the conical spring. The spring bracket 121 includes a base, an end cover 122 and one or more sets of flexible straps 123. The base includes a base of a spring mounting seat, and each spring mounting seat has a spring fixing portion for fixing one end of the conical spring 110. The end cover 122 is arranged opposite to and cooperative with the corresponding spring mounting seat to hold the conical spring 110, wherein the end cover 122 abuts against the other end of the conical spring 100 opposite to the end fixed in the spring mounting seat. Each set of flexible straps 123 includes a plurality of flexible straps spaced apart and evenly arranged between a corresponding pair of spring mounting seat and end cap. When one conical spring 110 is retained between the corresponding pair of spring mounting seat and end cap 122, the flexible straps 123 are located outside the conical spring 110. Alternatively, the sofa bed further includes a cover covering the conical springs.

Referring to FIG. 9 through FIG. 11, the main body frame is provided with slide rails (including a transverse slide rail 400 and longitudinal slide rails 300) which are configured in a way that a plurality of elastic modules 200 can be mounted on the main body frame from the outside of the main body frame and slide to a predetermined mounting position, so that a plurality of elastic modules 200 are closely arranged on a side of the main body frame facing the user (as shown in FIG. 12).

Preferably, the conical spring is mounted in the spring bracket with a predetermined initial compression force.

For example, referring to FIG. 9, the plurality of slide rails includes longitudinal slide rails 300, the longitudinal ends 301 of which are open, so that the elastic modules 200 can be received. Alternatively, the plurality of slide rails includes transverse side rails 400 whose transverse ends 401 are open so that the elastic modules 200 can be received.

Referring to FIG. 10 and FIG. 11, the plurality of slide rails include a plurality of longitudinal slide rails 300 extending in the longitudinal direction and a transverse slide rail 400 extending in the transverse direction. The longitudinal slide rails and transverse slide rails communicate at their intersections to facilitate the elastic modules 200 to switch side rails. Specifically, the transverse slide rail 400 is disposed in the middle of the longitudinal direction Y of the main body frame, and the transverse end 401 of the transverse slide rail 400 is opened to receive the elastic module 200 from the outside of the main body frame. The arrangement of the plurality of slide rails are designed such that the plurality of elastic modules 200 can enter the transverse slide rail 400 on the main body frame from the end of the main body frame, and switch to the longitudinal slide rails 300 at the intersection of the transverse slide rails 400 and the longitudinal slide rail 300.

In a state that a plurality of elastic modules 200 are closely arranged on the side of the main body frame facing the user as shown in FIG. 12, an outer covering may be further provided on the elastic modules to obtain a sofa bed finished product as shown in FIG. 13 and FIG. 14. FIG. 13 shows a configuration of the sofa bed finished product as a bed; FIG. 14 shows a configuration of the sofa bed finished product as a sofa.

The above depictions of various embodiments of the present invention are provided to those having ordinary skill in the art for depiction purpose, and are not intended to exclude other embodiments from the present prevention or limit the present prevention to a single disclosed embodiment. As described above, various alternatives and modifications of the present prevention will be apparent to those of ordinary skill in the art. Accordingly, although some alternative embodiments have been described in detail, those having ordinary skill in the art will understand or readily develop other embodiments. The prevention is intended to cover all alternatives, modifications and variations of the present prevention described herein, as well as other embodiments falling within the spirit and scope of the present prevention described herein.

Claims

1. A sofa bed, comprising: a main body frame (100) comprising a seat portion (4) and a backrest portion (3) arranged adjacent to each other, the seat portion (4) and the backrest portion (3) being configured to be folded or unfolded about a locking mechanism (34), so that the main body frame (100) transitions between a bed configuration and a sofa configuration; andan armrest frame (2) respectively disposed on both sides of the main body frame (100) in a longitudinal direction and connected to the main body frame (100) by the locking mechanism (34), wherein each of the armrest frames (2) is formed with a slideway (211) so that the movement of the locking mechanism (34) is guided by the slideway (211),wherein, when the backrest portion (3) and the seat portion (4) pivot relative to each other about the locking mechanism (34), the sofa bed is configured to lock the backrest portion (3) relative to the seat portion (4) at a predetermined angle (α), allowing the locking mechanism (34) to be guided by the slideway (211) n a locked state to drive the main body frame (100) to displace.

2. The sofa bed according to claim 1, wherein the locking mechanism (34) comprises: a seat portion connecting rod (41) attached to and extending along a transverse side edge of the seat portion (4);a backrest portion connecting rod (42) attached to a transverse side edge of the backrest portion (3) on the same side as the transverse side edge of the seat portion (4) and extending along the transverse side edge of the backrest portion (3); anda pivot shaft connecting the seat portion connecting rod (41) with the backrest portion connecting rod (42), so that the backrest portion (3) and the seat portion (4) can pivot relative to each other.

3. The sofa bed according to claim 1, wherein the main body frame (100) is configured to release the locking between the seat portion connecting rod (41) and the backrest portion connecting rod (31) when the seat portion (4) arranged in the locked stated is operated to pivot towards the backrest portion (3).

4. The sofa bed according to claim 3, wherein one of the seat portion connecting rod (41) and the backrest portion connecting rod (31) is provided with a ratchet (342), the other of the seat portion connecting rod (41) and the backrest portion connecting rod (31) is provided with a pawl, and the ratchet (342) and the pawl engage with each other so that the backrest portion (3) is locked at a predetermined angle (α) with respect to the seat portion (4).

5. The sofa bed according to claim 4, wherein an outer edge of the ratchet (342) is provided with a recessed portion that is recessed inward in a radial direction of the ratchet (342), the pawl is provided with a protruding portion corresponding to the recessed portion, and the protruding portion is configured to enable the protruding portion to engage with the recessed portion when the backrest portion (3) and the seat portion (4) form the predetermined angle (α), thereby locking the backrest portion (3) and the seat portion (4).

6. The sofa bed according to claim 1, wherein both the seat portion (4) and the backrest portion (3) are formed as a rectangular structure.

7. The sofa bed according to claim 6, wherein a side edge of the seat portion (4) extending in the longitudinal direction and a side edge of the backrest portion (3) extending in the longitudinal direction are arranged adjacent to each other.

8. The sofa bed according to claim 1, wherein the main body frame (100) is configured such that the backrest portion (3) can be locked at a plurality of different predetermined angles relative to the seat portion (4).

9. The sofa bed according to claim 1, wherein the main body frame (100) further comprises a driven beam (26), one end of which is pivotally connected to the armrest frame (2), and the other end of which is pivotally connected to the backrest portion (3).

10. The sofa bed according to claim 1, wherein the armrest frame (2) comprises a substantially -shaped armrest frame body (22) and a reinforcing transverse beam (21) connected between two legs of the armrest frame body (22), and wherein the slideway (211) is formed on the reinforcing transverse beam (21).

11. The sofa bed according to claim 10, wherein the locking mechanism is provided with a pin (341) extending toward the outside of the main body frame (100), and the slideway (211) is a sliding groove formed on the reinforcing transverse beam, wherein one end (211a) of the slideway is positioned higher than the other end (211b) of the slideway, and the one end (211a) is opened toward an upper edge of the armrest frame (2) to receive the pin (341) of the locking mechanism (34).

12. The sofa bed according to claim 10, wherein a sliding rod is provided on the reinforcing transverse beam, and the locking mechanism is provided with a sliding sleeve configured to journal on the sliding rod and slide along the sliding rod.

13. The sofa bed according to claim 10, wherein a sliding rod is provided under the reinforcing transverse beam (21b), and the sliding rod and a lower edge of the reinforcing transverse beam jointly define a sliding groove (213).

14. The sofa bed according to claim 10, wherein a cross section of the reinforcing transverse beam (21c) is in a shape of “”, and an outer end of the pin (341c) is provided with a protrusion having a shape that match with the “” shape.

15. The sofa bed according to claim 1, wherein the sofa bed comprises a bottom supporting structure (24) that is disposed under the backrest portion (3) and the seat portion (4) and is fixedly connected to the two armrest frames (2).