EP0406044B1 - Mechanism for sofa-bed - Google Patents

Description

The present invention relates to sofa beds and relates more particularly to sofa bed mechanisms.

There are known sofa bed mechanisms formed by an articulated frame carrying a folding mattress supplemented by a fixed back padding and removable seat cushions.

Such a mechanism which is described in US-A-3,813,710 comprises a hollow frame, a collapsible mattress support frame having a head portion, a central portion and a foot portion which are hinged together and which are movable between a generally horizontal sleeping position and a folded storage position in the chassis. The head section is longer than the other two sections to provide support for the user's head and shoulders and to allow the foot section to be cushion-length when folded.

Sections fold down to position the mattress on top in the folded position for comfort and the feet that support the sections on the floor in the sleeping position move to the folded position in response to the folding of the frame sections .

The main drawback of known sofa bed mechanisms is that they can only be combined with relatively thin mattresses, which reduces the comfort of the sofa bed when used in bed and requires adding seat cushions when the sofa bed is used as a sofa.

The invention aims to remedy the drawbacks of sofa beds of the prior art by creating a sofa bed mechanism which, while being relatively simple in construction and easy to handle, allows the use of a mattress '' sufficient thickness to make the sofa bed comfortable whether used as a bed or as a seat.

It therefore relates to a sofa bed mechanism comprising a support frame for a mattress, said frame being foldable and retractable in the folded position in a box defining the contours of the seat of the sofa bed, characterized in that it comprises a first assembly constituting the frame proper, means for locking the first assembly in the folded position and a second assembly for connecting the first assembly with the body and retracting therein the first assembly kept folded by the locking device, said first assembly forming the actual frame comprising a first frame section, a second frame section articulated on the first frame section and on a third frame section, the first frame section being further connected to the third frame section by a control linkage comprising a rectilinear rod articulated on the first section and a triangular rod articulated on the tr third section on the one hand directly and on the other hand by means of a light, by means of a triangular piece secured to a first foot also articulated on the third frame section as well as a fourth section of hinged frame on the third section and further connected thereto by a first connecting rod of the first leg with the fourth frame section and a second connecting rod of the first rod with a second hinged foot on the fourth frame section , the second assembly comprising, associated with each of the sides of the body, a fitting fixed to the corresponding side of the body, a connecting rod articulated on the one hand on the fitting and on the other hand at the free end of the first frame section , a bent piece articulated by one of its branches on the other end of the fitting and by its other branch on a connecting rod with said first frame section, said connecting rod of the fitting with the end of the frame section comprising a lug to which the end of a spring is fixed, the other end of which is fixed to the body, part of the mattress folded with the first set forming the seat of the sofa bed seat.

• la Fig.1 est une vue en élévation latérale d'un canapé-lit réalisé à l'aide d'un mécanisme suivant l'invention représenté en position déployée de lit ;
• la Fig.2 est une vue en élévation latérale du mécanisme dans une position intermédiaire ;
• la Fig.3 montre le mécanisme en position semi-repliée avant son introduction dans la caisse délimitant l'assise du canapé-lit ;
• la Fig.4 montre le mécanisme en cours de basculement en vue de son introduction dans la caisse de l'assise ou de son extraction hors de celle-ci ;
• la Fig.5 montre le mécanisme totalement replié en position de siège ;
• la Fig.6 est une vue schématique de dessus du mécanisme suivant l'invention montrant la structure de la surface de support du matelas ; et
• la Fig.7 est une vue partielle à plus grande échelle montrant le dispositif de verrouillage en position repliée de la partie du mécanisme supportant le matelas.

The invention will be better understood with the aid of the description which follows, given solely by way of example and made with reference to the appended drawings, in which:

• Fig.1 is a side elevational view of a sofa bed produced using a mechanism according to the invention shown in the deployed bed position;
• Fig.2 is a side elevational view of the mechanism in an intermediate position;
• Fig.3 shows the mechanism in semi-folded position before its introduction into the box defining the seat of the sofa bed;
• Fig.4 shows the mechanism being tilted for its introduction into the body of the seat or its extraction from it;
• Fig.5 shows the mechanism fully folded in the seat position;
• Fig.6 is a schematic top view of the mechanism according to the invention showing the structure of the support surface of the mattress; and
• Fig.7 is a partial view on a larger scale showing the locking device in the folded position of the part of the mechanism supporting the mattress.

In Fig.1, there is shown a sofa bed according to the invention comprising a box 1 intended to contain the mechanism of the sofa bed in the folded position and to define the contour of the seat of the sofa bed.

Box 1 has side walls such as the wall 2 carrying armrests, a front 3 of height less than that of the side walls 2 and a rear wall not shown.

It is surmounted by a backrest of which only the padding 4 is visible in the drawings.

The sofa bed mechanism according to the invention comprises an articulated frame designated by the general reference number 5.

This frame is formed of two articulated sub-assemblies such as the sub-assembly 6 shown in FIG. 1, each fixed by one of its ends to a side wall 2 of the body 1 of the sofa bed and interconnected by wooden slats 7 for example, as shown in Fig.6.

In Fig.6, there is shown schematically the sleeping surface a sofa bed according to the invention convertible into a double bed whose slats 7 which interconnect the articulated subassemblies 6 are in turn connected together in the longitudinal direction by a reinforcement strap 8 fixed in the middle of each of the slats, for example by at least one rivet 9. Several reinforcement straps of this type can also be provided.

With particular reference to Figs. 1 and 2, it can be seen that each of the articulated sub-assemblies 6 comprises a fitting 11 arranged diagonally against the inside of the side wall 2 of the body 1. At one end of the fitting 11 constituted for example by a flat iron is articulated a connecting rod 12. By its opposite end to the fitting 11, the connecting rod 12 is articulated on a gusset 13 secured to the end of a first frame section 14 located near the fixed backrest 4 of the sofa bed. The connecting rod 12 has a first tab 15 perpendicular to the direction of the connecting rod and to which is fixed a tubular crosspiece 16 for connecting the connecting rod 12 with a corresponding connecting rod forming part of the other articulated sub-assembly 6. The connecting rod 12 comprises a second tab 17 to which is fixed one end of a spring 18, the other end is fixed to the front 3 of the bed of the sofa bed.

To the gusset 13 of articulation of the connecting rod 12 is also fixed a backrest 19 extending between the end of the mattress support frame and the backrest 4 and intended to retain the mattress M during the folding operations of the sofa bed .

At its end opposite to the connecting rod 12, located at the bottom of the body, near the front 3 thereof, the diagonal fitting 11 is connected to a bent piece 20 roughly in the form of a square which, as shown in the drawings, almost always occupies a position in which one of its branches 20a extends approximately vertically, while its other branch 20b projects above the front 3 of the bed of the sofa bed outside the perimeter of this box.

The bent piece 20 is not retracted inside the body until the entire mechanics of the sofa bed is introduced into the body of the sofa bed.

At the free end of the bent piece 20 is articulated a connecting rod 21 whose opposite end is articulated in turn on the frame section 14 approximately two thirds of its length from the gusset 13.

The bent part 20 comprises at the junction of these two branches 20a and 20b, a stop 22 for limiting the angular displacement of the connecting rod 21 relative to this bent part.

The frame section 14 is part of a first set of the sofa-bed mechanism which will be described later, while the diagonal fittings 11 and the connecting rods articulated on these constitute a second set of connection of the first set with the body of the sofa bed and retraction of this first set in the body.

At the end of the first frame section 14 opposite the gusset 13, a second frame section 23 is articulated. The length of the second frame section 23 corresponds to approximately twice the thickness of the mattress M. On the second section of frame 23 is articulated in turn a third section of frame 24.

The control of the relative displacements of the first, second and third frame sections 14, 23 and 24 is ensured by a linkage comprising a rectilinear link 25 of which one end is articulated near the end of the first frame section 14 close to its articulation on the second section 23. At its opposite end, the link 25 is articulated on a triangular rod 26 mounted oscillating on the second section 23 at a point of articulation 27 and connected in turn by means of a light articulation 28 to a triangular part 29 secured to a first leg 30 articulated on the third frame section 24 by means of a hinge pin 31.

The articulation of the lumen 28 of the triangular connecting rod 26 on the triangular part 29 and the axis 31 of articulation of the first leg 30 on the third frame section 24, are arranged on two vertices of the triangular part 29 lying on a line corresponding to the direction of the third frame section 24. The third vertex of the triangular part 29 which is offset downward relative to the direction of the third frame section 24, carries an axis 32 of articulation of a rod 33 connecting the first foot 30 or central foot with a fourth section 34 of the frame, on which it is articulated by an axis 35.

At the end of the rod 33 opposite the first leg 30, is articulated a rod 36 connected to the rod 33 by an axis 37 located below the axis 35 of articulation of the rod 33 on the fourth frame section 34. At its opposite end, the rod 36 is articulated by a pin 38 at the upper end of a second foot 39 or front foot mounted oscillating on a leg 40 extending downwards, fixed to the fourth frame section 34 near its free end. The front leg 39 is articulated on the leg 40 by an axis 41.

When passing and keeping in the folded position, the resistance to folding of a comfortable mattress, that is to say a good thickness and a high density, must be overcome.

It can be seen more clearly in FIG. 2 that the fourth frame section 34 carries a support plate 42 intended to cooperate with an abutment rod 43 provided on the first leg 30 in order to ensure, during the folding of the mechanism, a reduction of the effort of angular displacement of the fourth frame section 34 in order to facilitate the locking of the sections 23, 24 and 14 in the folded position by means of the foot 30 which drives the triangular part 29 which, geared down, pulls on the triangular connecting rod 26, blocking between them the frame sections 23 and 24; the triangular connecting rod 26 pulls on the connecting rod 25 which blocks between them the frame sections 23 and 14. The fourth frame section 34 is locked to the second section 23 at the end of movement by a locking device fixed to the free end of the frame section 34.

The locking device of the fourth frame section 34 relative to the second section 23 in the folded position of the frame, comprises a fitting 44 fixed to the second section 23 and cooperating with a latch fixed to the free end of the fourth frame section 34 au- beyond the second foot 39 hinged thereon, for example on a cross member 34a completing the frame.

The bolt 45 comprises a bolt-forming part 46 mounted for rotation on an axis 47 and returned by a helical spring 48 in the closed position in which it engages with the fitting 44 by means of a lateral notch 49.

The part 46 has at its free end a maneuvering surface 50. At the free end of the fourth section 34 is also fixed a handle 51 intended to facilitate the manipulation of the frame during the operations of folding it.

The operation of the sofa bed mechanism according to the invention will now be described with reference to FIGS. 1 to 5.

As can be seen in Fig. 1, the sofa bed is in the fully unfolded position, in which it acts as a bed. The various frame sections 14, 23, 24 and 34 are aligned with one another and the legs 30 and 39 are in positions perpendicular to the general direction of the frame and form with the connecting rods 12 connected to the diagonal fittings. 11 carried by the body 1, supports for the sleeping surface.

We also note that the mattress M used is a one-piece mattress.

When it is desired to fold the sofa bed, the frame is raised by its fourth section 34, using the handle 51, which causes an angular displacement of the second section 23 relative to the first section 14, of the third section 24 relative to the second section 23, as well as the fourth section 34 relative to the third section 24. These various angular displacements are facilitated by the presence of at least one return spring 53 fixed between the gusset 13 and the third frame section 24 .

During this first part of the folding operation, the first frame section 14 remains stationary. The relative angular displacements of the second, third and fourth sections relative to each other, and relative to the first section 14, cause, due to the presence of the control linkages formed by the rectilinear rod 23, the triangular rod 26, the part triangular 29 integral with the first foot 30, the rods 33 and 36 connecting the foot 30 with the fourth frame section 34 and with the second foot 39, the progressive folding of the feet 30 and 39 by an angular displacement of these feet on their axes respective hinges 31 and 41, respectively towards the third frame section 24 and the fourth frame section 34.

This movement is visible in Fig. 2 which shows the mattress support frame in the partially folded position, the folds of the mattress M appearing at the joints of the second and third frame sections relative to the first, and of the fourth frame section compared to the third.

We also see in Fig. 2, that each fourth frame sections 34 is provided at its end situated opposite the corresponding third frame section 24, with a tip 34b cooperating with a stop surface 24b provided at the corresponding end of the third frame section 24. The stop 24b is intended to keep the third section 24 in alignment with the fourth section 34 when the sofa bed is in the unfolded position (Fig. 1).

Continuing the folding operation started in Fig. 2, the third frame section 24 is folded around the second frame section 23 and the fourth frame section 34 is folded over the third frame section 24 to a set whose relative position of the elements is shown in Fig.3.

In this figure, it can be seen that the second frame section 23 occupies a position perpendicular to the first section 14 while, owing to the proportions chosen for the link 25 and the triangular lever 26, the third frame section 24 occupies a position approximately near parallel to the first frame section 14, while the fourth frame section 34 is completely folded over the third frame section 24 the first and second legs 30, 39 also being folded in the common plane of the third and fourth frame sections 24 and 34.

This flat folding of the third and fourth frame sections and of the legs 30, 39 is obtained by judicious positioning of the articulation points of the legs 30, 39 relative to their corresponding frame sections 24, 34 on the one hand, and articulation axes of the rods 33 and 36 on the one hand, and on the other hand, with the various members with which they are associated.

In the folded position of the sleeping surface shown in FIG. 3, the mattress M is folded back on itself at S between the articulated sub-assemblies 6 so that the part of the mattress resting on the first frame section 14 is in contact with the part supported with the third frame section 23 to which the part of the mattress supported by the fourth frame section 34 is superimposed.

The assembly is held in this position by the locking device, the fitting 44 of which cooperates with the bolt-forming part 46 (FIG. 7). The fold of the mattress which results from the folding of the fourth frame section 34 onto the third frame section 23 is held in place by the backrest 19 at a short distance from the backrest 4.

We see that in the position shown in Fig.3, the frame serving as support for the mattress is folded back on itself and locked by the locking device 7 shown in Fig.7 and therefore constitutes a first assembly formed of first parts of the articulated sub-assemblies6 and ready to be moved once again for retraction into the bed of the sofa bed.

In this position, the connecting rods 12 and 21 as well as the bent piece 20, are always in the same position as they occupied when the sofa bed was in the fully unfolded position.

These various elements form the second parts of the articulated sub-assemblies 6 and constitute the second assembly for introducing the first sub-assembly into the body of the sofa bed.

In order to ensure the introduction of the first assembly into the box 1, the first is tilted sub-assembly by acting on the handle 51 to make the first frame section 14 oscillate as well as any assembly locked thereon around the bent piece 20 by means of the connecting rod 21 and around the diagonal fitting 11 by l 'through the connecting rod 12.

During this tilting, the first assembly defined above comes to occupy an intermediate position shown in Fig.4. We see that in this position, the connecting rod 21 has rotated around the corresponding end of the bent piece 20 until it is stopped in rotation by the stop 22, while the connecting rod 12 articulated at the upper end of the diagonal fitting 11 on the one hand and on the gusset 13 on the other hand, rotated around the end of the diagonal fitting 11, so as to bring the gusset 13 and the corresponding end of the first section 14 of the frame in the low position, near the bottom of the body 1 while causing the tension of the return spring 18. The assembly being in the position shown in Fig.4, is ready to be permanently retracted into the body 1.

To this end, it suffices to push on the first assembly to cause the bent pieces 20 to rotate about their respective articulation axes on the diagonal fittings 11. During this last movement, the frame section 14 oscillates relative to the connecting rods 21 and relative to the opposite ends of the diagonal fittings 11 by means of the connecting rods 12 to come to occupy a fully retracted position in the body shown in Fig.5.

The height under the backrest 4 is such that the mattress M can penetrate under the backrest and the the upper surface of its part supported by the fourth frame section 34 thus constitutes the seat surface of the sofa bed when the latter is in the sofa position.

To ensure the exit of the first assembly from the body 1, it suffices to pull on the handle 51 while lifting slightly. The return springs 18 which are under tension contribute to the output of the first assembly from the body 1.

When the mechanism is in the position shown in Fig.3, it suffices to unlock the first assembly by action on the bolt 46 and ensure the deployment of the frame while still acting on the handle 51.

The relative synchronous movement of all the moving parts allows that at the end of movement of the feet 30 and 39, are in appropriate positions to serve as support for the frame.

Furthermore, the deployment of the first assembly causes the springs 53 to be stressed, which, by the resistance which they oppose, compensate for the effects of the weight of the frame and avoid the user having to retain the mechanism during its deployment.

Thanks to the arrangement which has just been described, it is possible to use mattresses of sufficient thickness so that in the folded position, they constitute a seating surface sufficiently comfortable for the user and that in the position unfolded, they form in cooperation with the slats 7, a sleeping surface practically equivalent to that of an ordinary bed.

It can also be seen that the arrangement according to the invention makes it possible to use a mattress in one single piece.

The various constituent elements of the output and re-entry assembly of the frame supporting the mattress are sized to present synchronized deployment and folding movements.

In the embodiment which has just been described, when the sofa bed is in the deployed bed position, the fourth section 34 is perfectly aligned with the other sections of the frame and in particular with the third frame section 24.

However, if it is desired to be able to give the seating surface of the sofa bed a shape more corresponding to that of a sofa, that is to say lowering slightly towards the backrest, it is possible to provide means of articulation of the fourth frame section 34 relative to the rest of the frame, produced in such a way that in the deployed position, the fourth section is slightly inclined towards the ground relative to the rest of the frame, while making the mattress with a progressive wedge-shaped extra thickness in the region of the mattress supported by the fourth section.

Under these conditions, the mattress will be perfectly flat when the frame is in the deployed sleeping position and will form a slight recess towards the backrest when the mattress is folded.

To achieve such a result, it suffices to provide second feet 39 slightly shorter than the first articulated feet 30 and to move the joints of the feet 39 with their actuating rods 36, so that in the deployed position the fourth section has the desired inclination to compensate for the thickness of the seat in the folded position of the sofa bed.

Claims (8)

1. Mechanism for a sofa bed, comprising a support frame for a mattress (M), said frame being foldable and pivotable into a folded position in a box (1) defining the contours of the seat of the sofa bed, characterised in that it comprises a first assembly which constitutes the frame proper, means (44, 45) for locking the first assembly in the folded position and a second assembly for connecting the first assembly to the box(1) and for pivoting into said box the first assembly held in the folded position by the locking device; said first assembly forming the frame proper and formed by the sections (14, 23, 24, 34) of two articulated sub-assemblies (6), connected to each other by strips (7), comprising a first frame section (14), a second frame section (23) hinged to the first frame section (14) and to a third frame section (24), the first frame section (14) being moreover connected to the third frame section (24) by a control linkage comprising a rectilinear connecting rod (25) hinged to the first section (14) and a triangular rod hinged to the third section (24), partly directly (27) and partly by means of an opening (28), via a triangular piece which is integral with a first foot (30) which is also hinged to the third frame section (24) and a fourth frame section (34) hinged to the third section (24) and also connected to the latter by a first rod (33) connecting the first foot (30) to the fourth frame section (34) and a second rod (36) connecting the first rod (33) to a second foot (39) hinged to the fourth frame section (34), the second assembly comprising: associated with each side (2) of the box (1), a strap (11) fixed to the corresponding side (2) of the box, a strut (12) hinged on the one hand to the strap (11) and on the other hand to the free end of the first frame section (14); a cranked part 20 hinged by one of its arms (20a) to the other end of the strap (11) and by its other arm (20b) to a rod (21) for connecting with said first frame section (14), said rod (12) connecting said strap (11) to the end of the frame section (14) having a lock to which is fixed the end of a spring (18) the other end of which is fixed to the box (1), part of the mattress (M) folded with the first assembly forming the seating area of the sofa bed seat.
2. Mechanism for a sofa bed according to claim 1, characterised in that the third frame section (24) is also connected to the end of the first frame section (14) opposite its point of articulation on the second section (23), by at least one recoil spring (33) which retains the various elements of the first assembly when the sofa bed is unfolded.
3. Mechanism for a sofa bed according to claim 1 or 2, characterised in that the cranked parts (20) of the second assembly each comprise an abutment (22) limiting the angular movement of the corresponding rod (21) which connects the cranked part (20) to the first frame section (14), said rods (21) in the abutment position defining one of the pivot axes of the first frame section (24), to which is locked the first assembly when it has been folded for the purpose of pivoting said first assembly into the box (1) or for removing it therefrom.
4. Mechanism for a sofa bed according to one of claims 1 to 3, characterised in that each cranked part is hinged to the corresponding strap (11) in the bottom of the box (1) close to the front facade (3) of the box and, as a result of its pivoting about the end of the strap (11), constitutes a member for swivelling said first assembly into the box (1) and for taking it out of said box.
5. Mechanism for a sofa bed according to one of claims 1 to 4, characterised in that the strips (7) for connecting the hinged sub-assemblies (6) in order to form the frame proper are connected to one another in the longitudinal direction by means of at least one reinforcing belt (8).
6. Mechanism for a sofa bed according to one of claims 1 to 5, characterised in that said first assembly is provided with means (42, 43) for reducing the angular displacement force of the second, third and fourth frame sections (23, 24, 34) in order to facilitate the blocking and locking of these sections with the first frame section (14) using the locking device (44, 45) in spite of the resistance offered by the folding force of the mattress (M).
7. Mechanism according to one of claims 1 to 6, characterised in that said first frame section (14) has, at its end close to the back rest (4), a back portion (19) for retaining the mattress when said first assembly is folded.
8. Mechanism according to one of claims 1 to 7, characterised in that, in the deployed position, the fourth frame section (34) has a slight downward inclination relative to the third section (24) and in that the portion of the mattress (M) supported by the fourth secticn (34) has a wedge-shaped progressive over-thickness which is intended to provide, in the folded position of the sofa bed, a seating surface which is slightly reinforced towards the back.

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