Sofa bed

Abstract

The present description relates to a sofa bed, i.e., a sofa that can assume a flat, horizontal position, and thus serve as a bed. This application describes a sofa bed for placement on a flat surface, comprising an articulated tripartite structure, wherein the tripartite structure comprises a front module, an intermediate module, and a rear module, wherein each of said modules comprises two faces and at least one rigid element; wherein said modules are connected together by a first longitudinal rotation axis and a second longitudinal rotation axis, wherein the first longitudinal rotation axis connects an edge of the rear face of the front module to an edge of the front face of the intermediate module, and wherein the second longitudinal rotation axis connects an edge of the rear face of the intermediate module to an edge of the front face of the rear module, wherein the edge of the front face of the intermediate module and the edge of the rear face of the intermediate module are edges opposite to each other, wherein the forces exerted by the users on the first longitudinal rotation axis are transmitted to the front module and the forces exerted by the users on the second longitudinal rotation axis are transmitted to the rear module as a torque force, perpendicular to the plane connecting said longitudinal rotation axes.

Description

TECHNICAL FIELD

[0001] The present description refers to a sofa bed, i.e., a sofa that can assume a flat, horizontal position, and thus serve as a bed.BACKGROUND

[0002] A sofa bed is a versatile piece of furniture that serves as a sofa during the day and can be converted into a bed at night or whenever necessary. This piece of furniture is designed to combine the functions of sitting and sleeping in a single piece of furniture. There are several types of sofa beds, and they can vary in terms of design, conversion mechanism, and comfort.

[0003] Some common characteristics of sofa beds are related to their structure, conversion mechanism, mattress, upholstery used, size, or usage.

[0004] Regarding the structure, sofa beds generally have a solid frame that supports the mattress or the conversion mechanism. The frame can be made of wood, metal, or a combination of both. As for the conversion mechanism, there are different versions, such as the "clic-clac" opening type, sliding systems, and futon styles. In the case of the mattress, the quality and comfort of the mattress vary from one sofa bed to another. Some have thin built-in mattresses, while others allow the user to add a separate mattress. Regarding the upholstery, it can be made of fabric or leather, and the user can choose from a variety of colors and styles to match the surrounding decor.

[0005] Sofa beds are ideal for guest rooms, studios, living rooms, and other spaces where an extra sleeping option is desired without compromising space during the day.

[0006] It is known in the state of the art that there are various mechanisms for sofa beds, some with two elements, as in the case of document US6349431B1, and others with three elements, as in the case of document US5327591A.

[0007] There are also other solutions, such as the one proposed in document US7685655B1, wherein, in order to convert the sofa into a bed, the seat structure must slide forwardly, and for this purpose, the structure is equipped with castors.

[0008] In sofa beds, the width of the seat must be limited, as the width measurement cannot be excessive, otherwise, the user, in the sitting position, would not be able to sit comfortably with their back resting and their legs bent at the knees. The height of the backrest should not be disproportionate either, these limitations dictate that, for sofa beds with two modules, when this piece of furniture is converted into a bed, the user must lie in a direction parallel to the front of the sofa or the anterior face of the sofa. This aspect of limiting the choice regarding the positioning of the "headboard" can be understood as a disadvantage.

[0009] In the case of sofa beds with three modules, there are models where, when converted into a bed, the user can lie in a direction perpendicular to the front of the sofa. This allows the user to have their head oriented in the same direction, in both the sitting position (sofa) and the lying position (bed), which is considered an advantage, since for example, if the room is equipped with a television, the user can lie down and watch TV comfortably.

[0010] In general, in the case of sofa beds where the backrest is mobile, these pieces of furniture have more or less complex gears, always subject to failures or jams, and they also have a locking system for the backrest whenever the position is that of a sofa.

[0011] The document US6286159B1 comprises a lower element that fixes and elevates three modules, however in order for the sofa bed to function - which naturally means it must shift from the sofa position to the bed position and vice versa - the user must significantly lift the module to release the latches, which act as movement blockers, and this way being able to convert the sofa into a bed. This represents a significant inconvenience when the sofa bed is notably large and heavy. Additionally, this device was designed to be easily packaged, leading to its construction with various tubular pieces that can be mutually assembled and disassembled, and the bed frame core is made of a mesh. However, the mattress or padded part where the user will sit or lie tends to take on the sagging shape of the mesh, which is a drawback. Moreover, since the structure of this device is made of allegedly lightweight tubular material and lacks intermediate longitudinal reinforcement, it does not seem capable of functioning as a comfortable double bed, as it lacks the necessary solidity for that purpose.

[0012] In the furniture described in document US5519902A, even though the rear part of the sofa can be easily elevated, a mechanism to lock the backrest is still required. Furthermore, here as well, transitioning from a so-called "chaise longue" position to the bed position requires the effort of lifting the modules. On the other hand, in the sofa position, the seat is not parallel to the ground.

[0013] These facts are described to illustrate the technical problem solved by the embodiments of the present document.GENERAL DESCRIPTION

[0014] The present description relates to a sofa bed, i.e., a sofa that can assume a flat, horizontal position, and thus serve as a bed.

[0015] Throughout this application, a sofa bed is considered to be a versatile piece of furniture that combines the functionality of a sofa with the practicality of a bed, optimizing space usage in residential or commercial environments. Designed to offer comfort both for sitting and sleeping, this piece of furniture is ideal for small spaces or accommodating last-minute guests. In the sofa configuration, the sofa bed appears as a conventional seat with a backrest, potentially also having armrests and cushions, thus providing a cozy space for everyday activities, whether for watching TV, reading a book, or hosting visitors. Its design can vary widely, from more traditional styles to modern and minimalist options, adapting to different decors and personal preferences. The transformation of the sofa bed, now presented, into a bed is achieved through a simple opening mechanism, allowing the backrest to reveal a flat surface for sleeping. Sofa beds can be equipped with different types of mattresses, ranging from dense foams to pocket springs, aiming to provide proper support for the body during sleep. Ease of use, space-saving, and multifunctionality are key characteristics that make the sofa bed an intelligent solution for those seeking comfort and practicality. In addition to its functionality, sofa beds are also designed with attention to style and aesthetics, available in a wide range of fabrics, colors, and finishes, allowing them to harmoniously integrate into the environment where they are placed. Thus, besides being extremely practical, they contribute to the decoration and style of the space, offering an elegant solution for accommodation and rest needs.

[0016] The sofa bed for placement on a flat surface, now presented, comprises an articulated tripartite structure divided into at least three sequentially interconnected modules which, when in the sofa position, have a first module that assumes the seat position, referred to throughout the text as the front module, a second module that assumes the backrest position, referred to throughout the text as the intermediate module, and a third module that assumes a support position for the backrest relative to the structure, referred to throughout the text as the rear module.

[0017] In terms of vision and description throughout the text, it will always be considered that the sofa bed is faced in a perspective view towards the user, with the front face of the front module facing the user.

[0018] The sofa bed for placement on a flat surface, as now defined, comprises an articulated tripartite structure, wherein the tripartite structure comprises a front module, an intermediate module, and a rear module, wherein each of said modules comprises two faces and at least one rigid element, wherein said modules are connected to each other by a first longitudinal rotation axis and a second longitudinal rotation axis, wherein the first longitudinal rotation axis connects an edge of the rear face of the front module to an edge of the front face of the intermediate module, and wherein the second longitudinal rotation axis connects an edge of the rear face of the intermediate module to an edge of the front face of the rear module, wherein the edge of the front face of the intermediate module and the edge of the rear face of the intermediate module are edges opposite to each other, and in a more specific embodiment, they are positioned diametrically opposite, wherein the sofa bed is reconfigurable between two configurations, a first sofa configuration and a second bed configuration, wherein: in the sofa configuration, the front module lies on the flat surface, the rear module is raised on the flat surface, and the intermediate module is suspended between the front module and the rear module, and wherein the rear module comprises a flat surface on the back part thereof, so that, in the sofa configuration, it rests on the flat surface, in such a way that, when in the sofa position, if force is applied to the intermediate module, structural stability is maintained; and in the bed configuration, the front module, intermediate module, and rear module are aligned with the flat surface.

[0019] To better understand the technology, it is important to relate the relative positioning of the modules and their respective connections. Thus, in the sofa position, when viewing the sofa bed from the front, the front module comprises an upper face that serves as the seat and a rear face where it is connected to the intermediate module, which serves as the backrest. The intermediate module is thus connected to the front module by an edge of the rear face of the front module and an edge of the front face of the intermediate module, where a first longitudinal rotation axis is located, and to the rear module by an edge of the rear face of the intermediate module and an edge of the front face of the rear module. The rear module is connected to the intermediate module and to the surface of the base structure.

[0020] The respective modules are connected to each other by longitudinal rotation axes, which comprise hinges or other similar tools.

[0021] Thus, in one possible embodiment, the first longitudinal rotation axis between the front module and the intermediate module is located on the edge of the rear face of the front module and an edge of the front face of the intermediate module.

[0022] In one embodiment, the second longitudinal rotation axis is located in order to connect an edge of the rear face of the intermediate module to an edge of the front face of the rear module.

[0023] Geometrically, it is not mandatory for the modules to have a parallelepiped configuration; what is necessary is that there is a matching of shapes between the rear face and the anterior face of the front and intermediate modules, and between the rear face and the anterior face of the intermediate and rear modules.

[0024] In this way, it can be seen that the sofa bed now disclosed requires only two rotation axes, which allows for a remarkable technical simplification and cost savings in production and maintenance.

[0025] Thus, a sofa bed has been developed, aimed at operational simplicity, either by using simple and durable connections or by requiring minimal effort from the user when transitioning from sofa to bed and vice versa, with a reduced number of operations or movements.

[0026] In one embodiment, the sofa bed may also comprise a tripartite cover.

[0027] It is an objective of the present embodiments to provide a solution for a sofa bed with a surprisingly effective and simple-to-use conversion mechanism.

[0028] The present application describes a sofa bed for placement on a flat surface, comprising an articulated tripartite structure, wherein the tripartite structure comprises a front module, an intermediate module, and a rear module, wherein each of said modules comprises two faces and at least one rigid element; wherein said modules are connected together by a first longitudinal rotation axis and a second longitudinal rotation axis, wherein the first longitudinal rotation axis connects an edge of the rear face of the front module to an edge of the front face of the intermediate module, and wherein the second longitudinal rotation axis connects an edge of the rear face of the intermediate module to an edge of the front face of the rear module, wherein the edge of the front face of the intermediate module and the edge of the rear face of the intermediate module are edges opposite to each other, wherein the rear module comprises a flat surface on the back part thereof, so that, in the sofa configuration, it rests on the flat surface, wherein the sofa bed is reconfigurable between two configurations, a first sofa configuration and a second bed configuration, wherein: in the sofa configuration, the front module lies on the flat surface, the rear module is raised on the flat surface, and the intermediate module is suspended between the front module and the rear module, wherein the forces exerted by the users on the intermediate module are transmitted to the rear module as a torque force, perpendicular to the plane connecting said longitudinal rotation axes, where said force presses the rear face of the rear module against the flat surface; and in the bed configuration, the front module, the intermediate module, and the rear module are aligned with the flat surface, wherein the rear module comprises a flat surface on the back part thereof, so that, in the sofa configuration, it rests on the flat surface.

[0029] In one embodiment, the sofa bed for placement on a flat surface, comprising an articulated tripartite structure, wherein the tripartite structure comprises a front module, an intermediate module, and a rear module, wherein each of said modules comprises two faces and at least one rigid element; wherein said modules are connected together by a first longitudinal rotation axis and a second longitudinal rotation axis, wherein the first longitudinal rotation axis connects an edge of the rear face of the front module to an edge of the front face of the intermediate module, and wherein the second longitudinal rotation axis connects an edge of the rear face of the intermediate module to an edge of the front face of the rear module, wherein the edge of the front face of the intermediate module and the edge of the rear face of the intermediate module are edges opposite to each other, wherein the forces exerted by the users on the first longitudinal rotation axis are transmitted to the front module and the forces exerted by the users on the second longitudinal rotation axis are transmitted to the rear module as a torque force, perpendicular to the plane connecting said longitudinal rotation axes, wherein the sofa bed is reconfigurable between two configurations, a first sofa configuration and a second bed configuration, wherein: in the sofa configuration, the front module lies on the flat surface, the rear module is raised on the flat surface, and the intermediate module is suspended between the front module and the rear module; and in the bed configuration, the front module, the intermediate module, and the rear module are aligned with the flat surface, wherein the rear module comprises a flat surface on the back part thereof, so that, in the sofa configuration, it rests on the flat surface.

[0030] In one embodiment, the thickness of the front module combined with the depth of the intermediate module of the sofa bed is equal to or greater than the depth of the rear module, specifically, the thickness of the front module, combined with the depth of the intermediate module, is greater than the depth of the rear module.

[0031] In one embodiment, the flat surface of the sofa bed is a horizontal plane.

[0032] In one embodiment, the sofa bed additionally comprises a base, wherein the flat surface is part of said base, wherein the front module is fixed to said base.

[0033] In one embodiment, the base of the sofa bed serves as support for the rear module in the sofa position.

[0034] In one embodiment, each of the first and / or second longitudinal rotation axes of the sofa bed comprises at least one hinge, particularly a metal hinge, fabric hinge, Velcro, or elastic hinge.

[0035] In one embodiment, the tripartite structure of the sofa bed comprises a material selected from a list consisting of wood, metal, composite, polymer, or combinations thereof.

[0036] In one embodiment, the tripartite structure of the sofa bed comprises a tubular shape with a cross-sectional shape selected from a list consisting of rectangular, trapezoidal, or combinations thereof.

[0037] In one embodiment, the sofa bed further comprises a tripartite mattress, preferably a foam mattress.

[0038] In one embodiment, the sofa bed further comprises a cover.

[0039] In one embodiment, the sofa bed comprises feet fixed to the rear module.

[0040] In one embodiment, the sofa bed comprises an elastically deformable material, preferably an elastic or a spring.BRIEF DESCRIPTION OF THE DRAWINGS

[0041] For easier understanding, attached are drawings that represent preferred embodiments, which are not intended to limit the scope of the present description. Figure 1: Schematic representation of an embodiment of the sofa bed in the sofa position, showing the front, intermediate, and rear modules and their respective connections. Figure 2: Schematic axonometric representation of an embodiment of the sofa bed in the sofa position, showing the front, intermediate, and rear modules and their respective connections. Figure 3: Schematic representation of a right-side view of an embodiment of the sofa bed in the sofa position, showing the front, intermediate, and rear modules and their respective connections, with indications of the forces exerted by the user on the intermediate module when in the sofa position and the effect of these forces on the rear module.

[0042] In the aforementioned drawings, the following elements are indicated by reference numbers: 1 - front module; 2 - intermediate module; 3 - rear module; 4 - first longitudinal rotation axis; 5 - second longitudinal rotation axis; 6 - base; 7-tripartite mattress; 8 - arm rest support; a-a' - plane connecting said longitudinal rotation axes; f-force exerted on the intermediate module; f' -force transmitted to the rear module; fh' - horizontal component of the force transmitted to the rear module; fv' - vertical component of the force transmitted to the rear module. DETAILED DESCRIPTION

[0043] The present description concerns a sofa bed, i.e., a sofa that can assume a flat, horizontal position, and thus serve as a bed.

[0044] The described technology pertains to a sofa bed comprising an articulated tripartite structure provided with three modules, each of the three modules integrating an upper face / side, a lower face / side, a front face / side, a rear face / side, a right face / side, and a left face / side. The depth of the sofa bed is determined by the measurement from the front part to the back part of the sofa bed when it is in the sofa position. This dimension is crucial for understanding how much space the sofa bed will occupy in the room before being converted into a bed. The width of the sofa bed is given by the measurement from one lateral end to the other. When the sofa is in the sofa position, this dimension indicates the space it occupies side-to-side. In the bed position, it can also indicate the available width for sleeping, which is crucial for user comfort. The height is measured from the floor or a flat surface up to the highest point of the sofa bed, usually the top of the backrest when in the sofa position. Height is important both for aesthetics and functionality, affecting the ease of sitting and standing up. The front refers to the part of the sofa bed facing the user when used in the sofa configuration, i.e., where people sit. In the bed configuration, the front may refer to the visible side or the side opposite the backrest when in sofa form. The back or rear part refers to the area opposite the front, being the rear part of the sofa bed, which faces the wall or the space behind the sofa when in the sofa position. In the bed position, the back or rear part may refer to the same module as the sofa backrest in the sofa configuration. The longitudinal direction describes the extension of the sofa bed in the length direction, especially when opened as a bed, indicating the distance from the head zone to the foot of the bed, giving an idea of the space the furniture will occupy in the bed configuration. These definitions aid in understanding the specifications and measurements of a sofa bed throughout this text.

[0045] The geometry of the structure, as indicated in Figure 3, allows for structural stability in the sofa configuration. The forces exerted by the users on the intermediate module are distributed over two axes, axis E1 and axis E2. The forces exerted on axis E1 are transmitted to the front module / base assembly, which are solidary, due to their high stability as the base rests on the floor with an extended friction area. The forces exerted on axis E2 are transmitted to the rear module as a torque force, perpendicular to the plane connecting axes E1 and E2. Thus, a strong vertical component is gained, regardless of the direction of the force exerted by the user, provided this force does not exceed the limits of that same plane. This vertical component, combined with the gravitational force on the intermediate and rear modules, increases the friction on the anterior face of the front module in contact with the base, thereby ensuring the structural stability of the system.

[0046] The sofa bed for placement on a flat surface, comprising an articulated tripartite structure, wherein the tripartite structure comprises a front module, an intermediate module, and a rear module, wherein each of said modules comprises two faces and at least one rigid element; wherein said modules are connected to each other by a first longitudinal rotation axis and a second longitudinal rotation axis, wherein the first longitudinal rotation axis connects an edge of the rear face of the front module to an edge of the front face of the intermediate module, and wherein the second longitudinal rotation axis connects an edge of the rear face of the intermediate module to an edge of the front face of the rear module, wherein the edge of the front face of the intermediate module and the edge of the rear face of the intermediate module are edges opposite to each other, wherein the sofa bed is reconfigurable between two configurations, a first configuration as a sofa and a second configuration as a bed, wherein: in the sofa configuration, the front module lies on the flat surface, the rear module is raised on the flat surface, and the intermediate module is suspended between the front module and the rear module, wherein the forces exerted by the users on the intermediate module are transmitted to the rear module as a torque force, perpendicular to the plane connecting said longitudinal rotation axes, where said force presses the rear face of the rear module against the flat surface; and in the bed configuration, the front module, the intermediate module, and the rear module are aligned with the flat surface, wherein the rear module comprises a flat surface on the back part thereof, so that, in the sofa configuration, it rests on the flat surface..

[0047] In one embodiment, the sofa bed for placement on a flat surface comprises an articulated tripartite structure, wherein the tripartite structure comprises a front module, an intermediate module, and a rear module, wherein each of said modules comprises two faces and at least one rigid element, wherein said modules are connected together by a first longitudinal rotation axis and a second longitudinal rotation axis, wherein the first longitudinal rotation axis connects an edge of the rear face of the front module to an edge of the front face of the intermediate module, and wherein the second longitudinal rotation axis connects an edge of the rear face of the intermediate module to an edge of the front face of the rear module, wherein the edge of the front face of the intermediate module and the edge of the rear face of the intermediate module are edges opposite to each other, and in a more specific embodiment, they are in diametrically opposite positions, wherein the forces exerted by the users on the first longitudinal rotation axis are transmitted to the front module and the forces exerted by the users on the second longitudinal rotation axis are transmitted to the rear module as a torque force, perpendicular to the plane connecting said longitudinal rotation axes, wherein the sofa bed is reconfigurable between two configurations, a first sofa configuration and a second bed configuration, wherein: in the sofa configuration, the front module lies on the flat surface, the rear module is raised on the flat surface, and the intermediate module is suspended between the front module and the rear module; and in the bed configuration, the front module, the intermediate module, and the rear module are lying on the flat surface, so that when a force is applied to the intermediate module in the sofa position, structural stability is maintained, and wherein the rear module comprises a flat surface on the back part thereof to rest on the flat surface when in the sofa configuration.

[0048] In a further embodiment, the sofa bed may further comprise a cover.

[0049] In one embodiment, the thickness of the front module combined with the depth of the intermediate module of the sofa bed is greater than or equal to the depth of the rear module, specifically the thickness of the front module combined with the depth of the intermediate module is greater than the depth of the rear module.

[0050] In one embodiment, the flat surface of the sofa bed is a horizontal plane.

[0051] In one embodiment, the sofa bed further comprises a base, wherein the flat surface is part of said base, wherein the front module is fixed to said base.

[0052] In one embodiment, the base of the sofa bed supports the rear module in the sofa position.

[0053] In one embodiment, each of the first and / or second longitudinal rotation axes of the sofa bed comprises at least one hinge, particularly a hinge made of metal, fabric, Velcro, or elastic.

[0054] In one embodiment, the tripartite structure of the sofa bed comprises a material selected from a list consisting of wood, metal, composite, polymer, or combinations thereof.

[0055] In one embodiment, the tripartite structure of the sofa bed comprises a tubular shape with a cross-sectional shape selected from a list consisting of rectangular, trapezoidal, or combinations thereof.

[0056] In one embodiment, the sofa bed further comprises a tripartite mattress, preferably a foam mattress.

[0057] Similarly, the rear face / side of the intermediate module (2) and the front face / side of the rear module (3) are provided with a distance between them.

[0058] In one embodiment, the cover has been designed to provide comfort to the user, and its conception was intended to facilitate the operation of converting the sofa into a bed and vice versa. Thus, the cover is also a tripartite cover, like the sofa bed.

[0059] The sofa bed now disclosed can effectively and permanently serve as either a sofa or a bed, without the intent to be assembled and disassembled and stored according to a specific need, as in such cases, there is a focus on finding particularly lightweight structural solutions, which generally leads to the need to rely on a significant number of components.

[0060] In one embodiment, the articulated tripartite structure can be made of wood, metal, composite, polymer, or combinations thereof.

[0061] The sofa bed aims to offer an effective sofa or an effective bed, meaning that the user, whether sitting or lying down, can enjoy the same level of comfort offered by a traditional sofa or bed, which is why all three modules are equipped with at least one rigid element each.

[0062] In one embodiment, the articulated tripartite structure with rigid element may have a tubular shape, with a cross-section that can be rectangular, trapezoidal, or of another shape. For example, in the case of a rectangular cross-section, its right and left straight faces can be modified into arcs of a circle, with the invention possibly being implemented in other ways.

[0063] In one embodiment, the articulated tripartite structure in its first module (1) may be supported on a base, which will provide it with height.

[0064] In one embodiment, the sofa bed comprises feet fixed to the rear module for support in the bed position.

[0065] In one embodiment, the sofa bed comprises an elastically deformable material, preferably an elastic or a spring, which assists with the closing mechanism.

[0066] Figure 1 illustrates a schematic representation of one embodiment of the sofa bed in the sofa position, showing the front, intermediate, and rear modules and their corresponding connections.

[0067] Figure 2 illustrates a schematic axonometric representation of one embodiment of the sofa bed in the sofa position, showing the front, intermediate, and rear modules and their corresponding connections.

[0068] Figure 3 illustrates a schematic representation of a right-side view of one embodiment of the sofa bed in the sofa position, showing the front, intermediate, and rear modules and their corresponding connections, with an indication of the forces exerted by the user on the intermediate module when in the sofa position and the effect of those forces on the rear module.

[0069] The term "comprises" or "comprising" whenever used in this document is intended to indicate the presence of the characteristics, elements, integers, steps, and components mentioned, but not to preclude the presence or addition of one or more other characteristics, elements, integers, steps, and components, or groups thereof.

[0070] The present invention is, of course, in no way restricted to the embodiments described in this document, and a person of average skills in the art may foresee many possibilities for modification thereof and substitution of technical characteristics with equivalent ones, depending on the requirements of each situation, as defined in the appended claims.

[0071] The following claims define additional embodiments of the present description.

Claims

1. Sofa bed for placement on a flat surface, comprising an articulated tripartite structure, wherein the tripartite structure comprises a front module, an intermediate module and a rear module, wherein each of said modules comprises two faces and at least one rigid element; wherein said modules are connected together by a first longitudinal rotation axis and a second longitudinal rotation axis, wherein the first longitudinal rotation axis connects an edge of the rear face of the front module to an edge of the front face of the intermediate module, and wherein the second longitudinal rotation axis connects an edge of the rear face of the intermediate module to an edge of the front face of the rear module, wherein the edge of the front face of the intermediate module and the edge of the rear face of the intermediate module are edges opposite to each other, wherein the rear module comprises a flat surface on the back part thereof to rest on the flat surface in the sofa configuration, wherein the sofa bed is reconfigurable between two configurations, a first sofa configuration and a second bed configuration, wherein: in the sofa configuration, the front module lies on the flat surface, the rear module is raised on the flat surface, and the intermediate module is suspended between the front module and the rear module, wherein the forces exerted by the users on the intermediate module are transmitted to the rear module as a torque force, perpendicular to the plane connecting said longitudinal rotation axes, where said force presses the rear face of the rear module against the flat surface; and in the bed configuration, the front module, the intermediate module, and the rear module are aligned with the flat surface.

2. Sofa bed according to the previous claim, wherein the thickness of the front module combined with the depth of the intermediate module is greater than or equal to the depth of the rear module, in particular, the thickness of the front module combined with the depth of the intermediate module is greater than the depth of the rear module.

3. Sofa bed according to any of the previous claims, wherein the flat surface is a horizontal plane.

4. Sofa bed according to any of the previous claims, further comprising a base, wherein the flat surface is part of said base, wherein the front module is fixed to said base.

5. Sofa bed according to the previous claim, wherein the base supports the rear module in the sofa position.

6. Sofa bed according to any of the previous claims, wherein each of the first and / or second longitudinal rotation axes comprises at least one hinge, particularly a hinge made of metal, fabric, Velcro, or elastic.

7. Sofa bed according to any of the previous claims, wherein the tripartite structure comprises a material selected from a list consisting of wood, metal, composite, polymer, or combinations thereof.

8. Sofa bed according to any of the previous claims, wherein the tripartite structure comprises a tubular shape with a cross-sectional shape selected from a list consisting of rectangular, trapezoidal, or combinations thereof.

9. Sofa bed according to any of the previous claims, further comprising a tripartite mattress, preferably a foam mattress.

10. Sofa bed according to any of the previous claims, further comprising a cover.

11. Sofa bed according to any of the previous claims, comprising feet fixed to the rear module.

12. Sofa bed according to any of the previous claims, comprising an elastically deformable material, preferably an elastic or a spring.

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