ES2718176T3 - Mechanism for folding bunk beds - Google Patents

Description

DESCRIPTION

Mechanism for folding bunk beds.

The present invention relates to a mechanism for folding bunk beds and a sofa bed comprising said mechanism.

BACKGROUND OF THE INVENTION

To allow the closing or opening of a mechanism for folding bunks, it is known to use lever systems connected between the frame of the upper bed and the fixed base of the mechanism.

Among the known lever systems are those which, in order to achieve the closing movement of the berth, entail the 180 ° rotation of the upper bed frame.

In contrast, in other solutions, the lever systems comprise pivot axes that can be moved in a horizontal plane into the mechanism.

These known mechanisms are not devoid of drawbacks, among which mention must be made of the fact that the 180 ° rotation of the upper bed frame involves the use of ribbons in order to keep the mattress integral with the upper bed frame during the rotation.

In addition, lever systems that can move horizontally into the litter can lead to interference problems with the mattress of the lower bed frame.

In addition, mechanisms of the known type in general may have stability problems.

To ensure the safety of the user, locking systems are provided which prevent the upper bed frame, when in the raised position, from returning to the lowered position or, in any case, changing its own stable position for use.

These known locking systems are devoid of drawbacks, among which mention should be made of the fact that they are typically suitable only for the specific lever system used to raise and close the litter mechanism.

Furthermore, the known locking systems run the risk of being difficult to identify by the user, which, for this reason, can forget to activate them before laying down, for example, on the lower bed.

Another drawback of the known security mechanisms is constituted by the barriers arranged longitudinally on the upper bed frame, which are necessary to prevent the accidental fall of the user of the upper bed while sleeping. Said known safety barriers are typically uncomfortable to apply, particularly when the mechanism of the collapsible berth is used in a sofa bed, since in the closed configuration of the berth, they have to be removed in order to be able to use the sofa or they have to be folded on the upper bed frame under the corresponding mattress. Said known solutions, in addition to the discomfort of use, have less optimal security, since the user can use the upper bed in any case without mounting or raising the corresponding longitudinal safety barriers.

Another drawback of the known bunk mechanisms is that, in addition to safety sides, in order to reach the closed position of the bunk mechanism, it is necessary to remove the ladder that is used to access the upper bed.

BE 472 181 A discloses a double ottoman with upper and lower ottomans connected in an unfolded condition and adapted for a lifting movement to two lateral support frames, each comprising a pair of arms arranged as a scissor and connected to the lower ottoman, so that the upper surfaces of the two ottomans will be at the same height.

Summary of the invention

The purpose of the present invention is to overcome the drawbacks of the prior art by designing a folding bunk mechanism that is particularly robust and easy to move.

Within this aim, an object of the invention is to provide a movement mechanism for collapsible bunks that is not interposed between the upper and lower bed frames.

A further object of the invention is to provide a mechanism for collapsible berths that does not entail a rotation of the upper bed frame.

Another object of the invention is to provide a mechanism for collapsible bunks using an extremely limited number of levers while maintaining high structural stability.

Furthermore, a further object of the present invention is to conceive a mechanism for folding bunk beds that can be used to obtain a sofa bed.

Yet another objective of the present invention is to provide a safety mechanism for collapsible bunks that allows the user to lock the upper bed frame in position.

Within this purpose, an object of the invention is to make the security mechanism compulsory for the user to be able to use the litter.

Another object of the invention is to provide a safety mechanism that forces the user to assemble at least one longitudinal safety barrier of the upper bed frame in order to be able to use the litter. Another object of the present invention is to provide a mechanism for collapsible berths that avoids the need to have a removable ladder.

Another object of the invention is to provide a mechanism for folding bunks that is highly reliable, relatively easy to provide and at competitive costs.

According to the invention, a mechanism for folding bunks is provided as defined in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the invention will be more apparent from the description of preferred but not exclusive embodiments of the mechanism according to the invention illustrated by way of non-limiting example in the accompanying drawings, in which:

Figure 1 is a perspective view of a mechanism according to the invention in a fully open position;

Figure 1a is a detail view of a blocking element of Figure 1;

Figure 1b is a detail view of another blocking element of Figure 1;

Figure 2 is a view of the lowering motion of the lower bed frame;

Figure 3 is a view of the mechanism of Figure 1, in which the lower bed frame has been fully lowered;

Figure 4 is a view of an intermediate position of the upper bed frame during closure;

Figure 5 is a view of the mechanism of Figure 1 in the fully folded position;

Figures 6a-6c are views of three positions of one of the lever systems for moving the upper bed frame;

Figures 7a-7c are detail side views of the lever system for movement of the lower bed frame, respectively in the three elevated, inclined and lowered positions;

Figure 8 is a view of a bunk mechanism according to the invention in the raised position;

Figures 9a and 9b are views of the two positions of the security blocking element;

Figure 10 is a view of the sliding movement of the security barrier used in the mechanism of Figure 8;

Figure 11 is a view of the inclination movement of the security barrier used in the mechanism of Figure 8;

Figure 12 is a view of the inclination movement of the support frame used in the mechanism of Figure 8.

Description of preferred embodiments

With reference to the figures, a mechanism for folding berths according to the invention, generally designated by the reference number 1, comprises a base 2 which presents substantially a parallelepiped shape and is arranged on its opposite sides with lateral sides 21 connecting a front part 22 and a rear part 26 to form a containment seat for a lower bed frame 4. The side sides 21 are such that they project vertically with respect to said containment seat and to the surface of the lower bed frame, so that they can conveniently be used as barriers for the lateral containment of the mattress 43 and as frames in order to obtain the armrests of a sofa bed using the mechanism 1.

In addition, the front part 22 comprises at least a pair of support elements 24, for example brackets that are welded on the front part 22 and protrude into the containment seat formed on the base 2. The support elements 24 are adapted to support the lower bed frame 4 in its raised position and the upper bed frame 3 in its folded down position.

The lower bed frame 4 can be constituted by a pair of crosspieces 41 and a pair of longitudinal elements 42 to define a frame that is adapted to support a mattress 43, for example by means of wooden slats of a known type which are connected as a bridge between the longitudinal elements 42.

In addition, the mechanism 1 comprises an upper bed frame 3 which is also defined by a pair of crosspieces 31 and a pair of longitudinal elements 32 for defining a frame suitable for supporting a mattress 33, for example by means of wooden slats of a known type that are connected as a bridge between the longitudinal elements 32.

A front safety barrier 34 can be arranged in at least one longitudinal element 32 and is preferably detachably attached to said longitudinal element 32, for example by means of leaflets. Additional safety barriers 35 which are not necessarily removable and are useful for preventing the sliding of the mattress 33 on the surface of the upper bed frame 3 may be present in the crosspieces 31.

The side sides 21 of the base 2 are connected to the crosspieces 31 of the upper bed frame by means of respective first lever systems 5 which are adapted to allow the movement of the upper bed frame 3 moving away from the base 2 and approaching is. Each of the first lever systems 5 defines an articulated quadrilateral which is located on a plane that is substantially perpendicular to the plane of the upper bed frame 3.

The articulated quadrilateral is preferably an articulated parallelogram 6 shown in broken lines in figures 6a-6c and has a hinge obtained, for example, by means of an articulated joint 61, whose pivot axis coincides with the longitudinal axis of the upper bed frame 3 passing substantially through the center of the crosspieces 31 of the upper bed frame 3. The articulated parallelogram 6 further has two additional hinges which are integral with the base 2 and are also preferably obtained by means of articulated joints 62 and 63. The fourth hinge of the articulated parallelogram 6, preferably also obtained by means of an articulated joint 64, is integral with the movement of the upper bed frame 3 and the same occurs with the articulated joint 61.

A short side of the parallelogram 6 is defined between the joints in a fixed position with respect to the base 2, that is, the joints 62 and 63, and is inclined with respect to the support surface on the floor of the base 2 to define an acute angle towards the rear part 26 of the base 2, for example of approximately 60 °. In this way, with the closing movement of the berth, the seal 61 which is arranged in the upper bed frame 3 can approximate the fixed joints 62 and 63, allowing the upper bed frame 3, in the folded position, to be disposed substantially on the lower bed frame 4.

The articulated joints 61, 62, 63 and 64 may be adapted to allow a mutual rotation of no more than about 90 ° between the levers that are connected thereto. Said levers are preferably four L-shaped levers 52-53 and 54-55 which are identical in pairs and are adapted to define a substantially rectangular shape and, more preferably, a square shape when the upper bed frame 3 is in the position completely elevated with respect to base 2.

A first L-shaped lever 52 is fixed rigidly to an inner side of the respective side side 21 of the base 2, and a second L-shaped lever 53 is fixed rigidly laterally to the upper bed frame 3, for example, by an angled fastening element 533 which is fixed along the respective cross member 31 to prevent relative rotation between the upper bed frame 3 and said second L-shaped lever 53. The L-shaped levers 52 and 53 are traversed by a diagonal of form substantially rectangular of the lever system 5, while the third L-shaped lever 54 and the fourth L-shaped lever 55 are traversed by the other diagonal of said substantially rectangular shape.

With the structure described above, a rotation of the upper bed frame 3 around itself during its opening and closing movements is prevented.

The first and second L-shaped levers 52 and 53 each comprise two arms that are arranged at right angles to each other and have a substantially identical extension 521-522 and 531 532, respectively, and are connected by a curved part. . The third and fourth L-shaped levers 54 and 55 also each comprise two arms 541-542 and 551-552, respectively, which are oriented at right angles to one another and have a substantially identical extension therebetween which is greater that the extension of the arms 521-522 and 531-532 of the first and second L-shaped levers 52 and 53.

The mutually pivoted arms are substantially perpendicular to each other when the upper bed frame 3 is in the folded position, as shown in Figure 6c, in which the first lever system 5 is interposed between the side side 21 of the base 2 and the crosspiece 31.

The third L-shaped lever 54 advantageously comprises a blocking element for preventing movement of the first lever system 5. Such locking element can be obtained by means of a locking element 543 on the arm 541, which is provided with a bolt. 544, which can be moved between an extended position in which the bolt 544 abuts the side side 21 of the base 2 and a retracted position in which the bolt 544 does not protrude transversely from the third L-shaped lever 54 and allows its rotation with respect to the first L-shaped lever 52. The bolt 544 can be moved by means of a removable key 546.

Another locking element 533 can be arranged between the first lever system 5 and the upper bed frame 3, for example in the form of a bar 554 that can slide on a fork-shaped bracket 555 which is fixed below the arm 551 of the fourth L-shaped lever 55 for removably engaging below the respective crosspiece 31.

The arm 541 can further be connected to a gas cylinder actuator 23, for example by means of a plate 545 in a position which is substantially intermediate to the arm 541. The gas cylinder actuator 23 is connected, at its other end, to the rear part 26 or the side 21, preferably at a point that is substantially aligned vertically with the hinge 62 and is close to the bearing surface of the base 2 to facilitate the opening and closing movements of the upper bed frame 3 .

As an alternative to the gas cylinder actuator 23 it is possible to use a motorized actuator.

Advantageously, the first lever systems 5 can be rigidly connected to each other by transverse reinforcing bars, for example by a reinforcing bar 56 which is welded between the fourth L-shaped levers 65 on the arms 552. The reinforcing bar 56, if it is welded next to the joints 62, it can advantageously constitute a support element for the cushions of the rear part of the sofa bed using the mechanism 1 according to the invention.

Each of the L-shaped levers 52, 53, 54, 55 can also have angular reinforcement elements 57 which are arranged similarly to a bridge between the respective arms.

The lower bed frame 4 of the mechanism according to the invention can also be raised with respect to the base 2 by means of the second lever systems 71 and 75.

In particular, at each of the opposite longitudinal ends of the lower bed frame 4, it is possible to provide a first lower lever 71 having an end which is pivoted on a substantially intermediate point of a cross member 41 of the lower bed frame 4 and the another end pivoted on the front part 22 of the base 2, for example on a vertical extension 25 of the bracket constituting the support element 24.

The first two lower levers 71 can have a bracket 73 in a substantially intermediate position in which a rod 72 for connecting the first two lower levers 71 is fixed and is arranged below the lower bed frame 4. The bracket 72 can be connected by means of from a spring 74 to the front part 22 of the base 2, preferably at a level higher than the pivot point of the lever 71 on the vertical extension 25 of the support element 24, so that the spring 74 is disposed substantially in parallel to the crosspieces 41 of the lower bed frame 4 when said frame is in the raised position, shown in Figures 1 and 7a.

In contrast, the corner ends of the crosspieces 41 on the opposite side with respect to the front part 22 are connected to the second lower levers 75, each pivoted between one of said corner ends or a bracket which is integral with the same and the rear part 26 of the base 2, for example at a point substantially at the same height as the pivot point of the first lower levers 71 on the front part 22 of the base 2. The second lower levers 75 can be connected also rigidly to one another by a connecting rod which is welded on the second lower levers 75 proximate to its pivot point at the rear part 26 of the base 2.

The operation of the invention is evident from the embodiment described above.

In particular, considering the initial situation of Figure 1, when the berth has to be folded, the lower bed frame 4 is raised on the longitudinal element 42 and, with a combined rotational and translational movement, the lower bed frame 4 on a position that is thus inclined, is lowered with the rotation of the second lower levers 75 about its pivot point on the rear part 26 of the base 2. The lower bed frame 4 is then pushed down to cause it to stop in a substantially horizontal position with respect to the bearing surface of the base 2.

By means of the key 546, the locking systems 543 are then opened so that the bolts 544 no longer project transversely from the arm 541 of the L-shaped third lever 54 which can thus freely rotate around the articulated joint 63 with respect to to the lateral sides 21. The bars 554 can also be uncoupled, by manually moving them outwards so as not to stop under the respective crosspieces 31. Applying a downward force to the upper bed frame 3, as shown in figure 3, the upper bed frame 3 is manually lowered, remaining substantially parallel to the bearing surface of the base 2 and guided by the first lever systems 5 and by the gas cylinder actuator 23, until it abuts against the support elements 24 arranged in the front part 22 of the base 2. In contrast, the opening movement of the berth follows the steps that are the opposite to those described above.

Advantageously, the mechanism described above can be used in a sofa bed, adding back cushions to the mechanism in the folded position shown in figure 5 in order to obtain a sofa.

According to another aspect of the invention shown in Figures 8 to 12 in particular but not necessary use in combination with the mechanism 1 described above, the base 2 may comprise a support frame 600 that can be rotated with respect to the base 2, in particular with respect to a longitudinal axis A thereof. Such support frame 600 can be pivoted on a front longitudinal member of the base 2 by means of two struts 610 connected by a crosspiece 620 preferably having a longitudinal extension that is substantially equal to that of the longitudinal elements 32 of the upper bed frame 3. In contrast, the struts 610 have an extension that is substantially equal to or greater than the height difference, with respect to the plane of the base 2, between the pivot axis A of the support frame 600 and the bed frame upper 3 when the latter is in the fully elevated position.

In this way, when the support frame 600 is in the raised position, the corresponding cross member 620 is at a height, with respect to the plane of the base 2, which is substantially equal to the height of the upper bed frame 3 and the struts 610 can accordingly be used to frontally support the weight supported by the upper bed frame 3 and discharge it onto the base 2.

In contrast, when the support frame 600 is in the lowered position, it rests on the lower bed frame 4, more precisely above the mattress 43 disposed on the lower bed frame 4 to be visible when the upper bed frame 3 moves towards the elevated position.

Advantageously, a ladder 670 moving rigidly together with the supporting frame 600 is defined in the support frame 600. One of the side members of the ladder 670 can be one of the struts 610, while the other side of the ladder 670 it is fixed to the crossbar 620 at one end and is pivoted at the other end along the same pivot axis A as the support frame 600. The steps of the ladder 670 are thus fixed to these two uprights, for example by welding.

An assembly 640 for blocking movement of the upper bed frame 3 is arranged on the cross member 620 of the support frame 600 and is adapted to interact with the front longitudinal element 32 of the upper bed frame 3 when the support frame 600 is in the elevated position in order to maintain this position and allow the discharge of the weight on the base 2.

This locking assembly 640 can be obtained by means of at least one bolt coupled to the cross member 620. To achieve locking, the bolt interacts with suitable stops 660 which are rigidly fixed to the upper bed frame 3, for example to the longitudinal element 32 .

A safety barrier 630 can be pivoted to the cross member 620 of the support frame 600 and can rotate between an inactive position, in which the safety barrier can rotate freely with respect to the support frame 600, and a safety position in which the barrier 630 is external to the perimeter of the support frame 600 and is located in a locked condition in a plane that is substantially perpendicular to the plane of the upper bed frame 3. In the safety position, the rotation of the safety barrier 630 is blocked up.

Advantageously, the security barrier 630 can integrate the blocking assembly 640. In particular, the bolts 650 are rigidly fixed to the security barrier 630 substantially on the pivot axis of the security barrier on the crosspiece 620 of the support frame 600 .

In this way, by means of the rotation of the safety barrier 630 from the inactive position to the safety position, it is possible to achieve not only the locking of the support frame 600 in the upper bed frame 3, but also the blocking of the the rotation of the safety barrier 630 with respect to the cross member 620. In the particular illustrated embodiment, the bolts 650 are oriented substantially parallel to the crosspiece 620 of the support frame 600. For example, each bolt 650 can be fixed to one of the two arms of a fork that is rotatably engaged in the cross member 620, the other arm of the fork being secured to the safety barrier 630.

The security barrier 630 can further slide along the crossbar 620 so that when the security barrier 630 slides, the bolts 650 engage in corresponding stops 660, for example tubular elements which are fixed on the longitudinal element 32. of the upper bed frame 3. Optionally, in order to prevent the inadvertent release of the security barrier 630, it is possible to provide a security blocking element 680 which can be operated by means of a removable key and prevent, once activated , the sliding of the safety barrier 630 along the crossbar 620. The blocking element 680, for example, may interact with a stop 690 projecting from the cross member 620 of the support frame 600. As an alternative, said stop may be arranged in the longitudinal element 32 of the upper bed frame 3.

Optionally, it is possible to provide at the crosspiece 620 of the support frame 600 at least one spring latch 700 adapted to automatically engage the upper bed frame 3 by means of a spring that is loaded towards said upper bed frame in order to preventing the support frame 600 from falling down during the operations for moving the safety barrier 630. The spring latch 700 can be deactivated by manually pulling a ring that is integral with the spring latch. However, in order to maximize the safety of the structure, it is preferable to avoid using the spring latch 700.

The operation of the security mechanism according to the invention is evident from the embodiment just described. In particular, when the upper bed frame 3 is moved by the user to the raised position, the support frame 600 becomes visible and, therefore, is raised by the user, for example by grasping the safety barrier 630. The Support frame 600 is then rotated with respect to base 2 until it reaches the raised position. This position can be optionally defined by an angular stroke limit.

The safety barrier 630 is then rotated further to move it to the safety position. In this position, the bolts 650 are aligned with respect to the corresponding rings 660 of the upper bed frame 3. Finally, the user pushes the safety barrier 630 to make it slide relative to the cross member 620 of the support frame 600 and insert bolts 650 on rings 660.

Therefore, the frame 600 can support the weight of the upper bed while it remains locked in position. In this position, the user can use the ladder 670 which is integrated in the support frame 600.

When the bunk is to be closed, the security barrier 630 is moved along the crossbar 620 to move the bolts 650 out of the rings 660 and the entire support frame 600 is finally accompanied by the user until it rests on the mattress 43 of the lower bed frame 4.

In practice it has been found that the folding bunk mechanism according to the invention completely achieves the intended purpose, since it allows to have a rigid and secure structure with a very limited number of components.

Furthermore, the closure of the berth is achieved with the upper bed frame which always remains substantially parallel to the ground and using lever systems that can move exclusively on substantially vertical planes, advantageously interposed between the lateral sides of the base and the crosspieces of the bed. the upper and lower bed frames.

In addition, security can be increased. The security mechanism according to the invention that can be used with the mechanism described for folding bunk beds but also with other mechanisms adapted to fold bunk beds, must in fact be considered by the user, since in addition to being clearly visible because it is located on the mattress of the lower bed, prevents the user from accessing the lower bed. In addition, thanks to the integrated ladder, access to the upper bed is prevented if the safety mechanism is not activated.

In addition, thanks to the fact that a safety barrier is integrated, the safety mechanism according to the invention prevents the user from having to remember to mount said barrier before laying on the upper bed.

The invention thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the appended claims; all the details can be replaced by other technically equivalent elements.

In practice, the materials used, as well as the dimensions, can be any according to the requirements and the state of the art.

Claims (18)

A mechanism (1) for collapsible berths, comprising a base (2) and an upper bed frame (3) which are connected, on opposite sides, by a pair of first lever systems (5) adapted to allow movement of the upper bed frame (3) between two stable positions above the base (2), the upper bed frame being adapted to support a mattress (33), each of said first lever systems (5) comprising a quadrilateral articulated (6) which is located on a plane that is substantially perpendicular to the plane of said upper bed frame (3), characterized in that said articulated quadrilateral is an articulated parallelogram (6) and is composed of four L-shaped levers that they are identical in pairs (52, 53, 54, 55) and are adapted to define a substantially rectangular shape when the upper bed frame (3) is in the fully elevated position with respect to said base (2), a first L-shaped lever (52) of between said L-shaped levers is fixed rigidly to the base (2) and a second L-shaped lever (53) of between said L-shaped levers is fixed rigidly to the upper bed frame (3), said first and second L-shaped levers (52, 53) being traversed by a diagonal of said substantially rectangular shape, the third and fourth L-shaped levers (54, 55) being said L-shaped levers traversed by the other diagonal of said substantially rectangular shape, each of said first and second L-shaped levers (52, 53) comprises two arms (521, 522; 531, 532) that are substantially perpendicular to each other and each of said third and fourth L-shaped levers. (54, 55) comprises two arms (531, 532, 541, 542) that are substantially perpendicular to each other and are longer than the length of the arms (521, 522; 531, 532) of the first and second arms L-shaped levers (52, 53), the pivoted arms being substantially perpendicular to each other when the upper bed frame (3) is in the fully folded down position. Mechanism according to claim 1, characterized in that said articulated quadrilateral (6) comprises a hinge (61) on a longitudinal axis of said upper bed frame (3) and two hinges (62, 63) on said base (2) . Mechanism according to claim 2, characterized in that said longitudinal axis of said upper bed frame passes through a substantially central point of the crosspieces (31) of said upper bed frame (3). Mechanism according to one or more of the preceding claims, characterized in that the third L-shaped lever (54) pivoted to said base comprises a blocking element (543) to prevent the movement of said first lever system (5) with respect to a lateral side (21) of said base (2), said fourth L-shaped lever (55) optionally comprising a second blocking element (553). 5. Mechanism according to one or more of the preceding claims, further comprising a lower bed frame (4) that is adapted to support a mattress (43), said lower bed frame (4) being arranged below the bed frame upper (3) and being movable with respect to the base (2) between an elevated position and a lowered position, by means of a few second lever systems (7) that are connected between said base (2) and said crosspieces (42) of said lower bed frame (4), said second lever systems (7) being able to rotate on planes that are substantially perpendicular to the plane of said lower bed frame (4). Mechanism according to claim 5, characterized in that said base (2) has substantially a parallelepiped shape to define a containment seat in order to completely accommodate the lower bed frame (4) in the lowered position, said base comprising (2), on each side where said first lever system (5) is pivoted, a lateral side (21) projecting above said containment seat of the lower bed frame (4) and which is laterally adjacent to said upper bed frame (3) in the folded down position. Mechanism according to one or more of claims 5 and 6, characterized in that said base (2) comprises at least one support element (24) on a front part (22) that is substantially perpendicular to the sides of the base (2) where the first lever systems (5) are connected, said at least one support element (24) adapted to support said lower bed frame (4) in its raised position and said upper bed frame (3) ) in its completely down position. Mechanism according to one or more of claims 5 to 7, further comprising a safety mechanism comprising a support frame (600) which is connected to said base (2) and which can rotate with respect to a longitudinal axis of said base (2) between an inactive position, in which the support frame (600) is located substantially above the lower bed frame (4), and a raised position, in which the support frame (600) is coupled to the upper bed frame (3) so that it supports its weight along the a longitudinal element (32) of said upper bed frame (3), said support frame (600) comprising a locking assembly (640) which is adapted to detachably fix said support frame (600) to said upper bed frame (3). 9. Mechanism according to claim 8, characterized in that said support frame (600) is pivoted to the base (2) by means of two struts (610) connected by a crosspiece (620), which has a longitudinal extension that is substantially equal to that of the longitudinal element (32) of the upper bed frame (3), said struts (610) having an extension that allows the crosspiece (620) to be at a height, with respect to the support surface of the base ( 2) that is substantially equal to the height of the upper bed frame (3) when the support frame (600) is in said elevated position. Mechanism according to one or more of claims 8 and 9, characterized in that the locking assembly (640) comprises at least one bolt (650) which is coupled to the crosspiece (620) of the support frame (600), comprising said upper bed frame (3) stops (660) adapted to match said at least one pin (650) in order to detachably fix said support frame (600) to said upper bed frame (3). 11. Mechanism according to one or more of claims 8 to 10, characterized in that a safety barrier (630) is pivoted to the crosspiece (620) of the support frame (600), said safety barrier (630) being able to rotate between an inactive position, in which the safety barrier can rotate freely with respect to said support frame (600), and a safety position, in which the barrier (630) is locked with respect to the support frame (600 ) and is located in a plane that is substantially perpendicular to the plane of the upper bed frame (3). 12. Mechanism according to claim 11, characterized in that the security barrier (630) comprises said blocking assembly (640). 13. Mechanism according to claim 12, characterized in that said locking assembly (640) comprises said at least one bolt (650) that is rigidly fixed to the safety barrier (630) substantially on the pivot axis of the barrier safety (630) on the crosspiece (620) of the support frame (600). 14. Mechanism according to claim 13, characterized in that said at least one bolt (650) is directed substantially parallel to the cross member (620) of the support frame (600) and the safety barrier (630) can also slide as far as possible. length of said cross member (620), so that when the safety barrier (630) slides along the crosspiece (620), said at least one pin (650) engages with said upper bed frame (3) in order to detachably fix said support frame (600) to said upper bed frame (3). 15. Mechanism according to claim 14, characterized in that said safety barrier (630) further comprises a blocking element (680) to prevent or allow said sliding. 16. Mechanism according to one or more of claims 8 to 15, characterized in that a ladder (670) is defined on the support frame (600) and can move integrally with the support frame (600). 17. Mechanism according to one or more of claims 8 to 16, characterized in that said support frame (600) comprises at least one spring latch (700) that is adapted to be coupled with said upper bed frame (3). 18. Sofa bed, characterized in that it comprises the mechanism (1) according to one or more of the preceding claims.