[0001] The present invention deals with an element for fastening the supporting plane, formed
either as a bedspring or as a plurality of staves, to a chair-bed or sofa-bed frame.
[0002] It is known that the supporting plane of the above mentioned pieces of furniture
may, at choice, consist of a bedspring or of staves generally made of wood.
[0003] It is also known that a bedspring has been, for a long time, the only means adopted
to provide the supporting plane of a chair-bed or of a sofa-bed, while the present
tendency, gradually spreading, is to employ staves as therewith the supporting plane,
even if having a certain resilience, is sufficiently rigid to give the user a comfort
not attainable with the bedspring which, as it is well known, is too yielding.
[0004] The bedspring, besides the above mentioned drawback, which is anyhow a subjective
factor varying from a person to another, has a further drawback consisting in that
its perimetric fastening to the chair-bed or sofa-bed frame has a limited resistance
to the stresses.
[0005] The above mentioned drawback is caused by the fact that the bedspring is fastened
to the chair-bed or sofa-bed frame by means of springs connected at one end to the
metal net of bedspring while the other end, properly folded, is inserted into a frame
hole.
[0006] The supporting plane with staves results to be more resistant, as the end itself
of each stave is connected to the frame by sliding therein or by interposition of
a connecting element having, on one side thereof, a seat suitable to receive the stave
end while on the other side it has an appendix which is secured to the frame usually
by means of a rivet or of a screw.
[0007] The above mentioned realization results however economically disadvantageous either
because of the staves cost or because their mounting, direct or by interposition of
said connecting element, involves long preparation works which increase the time necessary
to the supporting plane formation.
[0008] A further drawback of the realization by means of staves with intermediate element
for the connection to the frame consists in that the securing of the element for the
connection to the frame results scarcely resistant to the stresses.
[0009] Now it has been conceived and is the object of the present invention an element for
fastening the supporting plane, formed either as a bedspring or as a plurality of
staves, to the chair-bed or sofa-bed frame, which allows to overcome all the above
mentioned drawbacks.
[0010] In the following, only for the sake of brevity, the reference to the chair-bed or
sofa-bed will be simply indicated with "sofa".
[0011] The characteristics as well as the advantages of the fastening element according
to the present invention will be clear from the following detailed description of
a non-limiting embodiment thereof with reference to the attached drawings in which:
Figure 1 is a schematic perspective view of a supporting plane for a sofa with bedspring employing
the fastening element according to the present invention;
Figure 2 is a cross section view of the supporting plane taken along line II-II of Fig. 1;
Figure 3 is a perspective view showing the fastening element applied to the supporting plane
of Fig. 1 in operating condition;
Figure 4 is a perspective view of the fastening element of Fig. 3 in overturned position to
show the securing elements it is provided with;
Figures from 5 to 7 and from 5a to 7a are respectively cross section and lengthwise section views showing the operating
steps for applying the fastening element to the sofa frame;
Figure 8 is a schematic perspective view showing a supporting plane formed by staves and employing
the fastening element according to the present invention;
Figure 9 is a cross section view of the supporting plane taken along line IX-IX of Fig. 8;
Figure 10 is a perspective view of the fastening element applied on the supporting plane in
operating conditions;
Figure 11 is a view of the fastening element of Fig. 10 in overturned position to show the
securing means it is provided with;
Figures 12 and 13 and Figures 12a and 13a are respectively cross section and lengthwise section views showing the operating
steps for applying the fastening element to the sofa frame.
[0012] With reference in particular to Fig. 1 there is seen a sofa supporting plane substantially
rectangular but that could be also of different shape.
[0013] Said supporting plane comprises a bedspring 10 which is linked to the sofa frame
12 by means of a plurality of fastening elements according to the present invention
which are referenced to as a whole by 14.
[0014] The frame 12 consists of a metal tubular section whose shape, in cross section, can
be seen particularly in Fig. 2. From said figure it appears that frame 12 has a cross
section of a suitable shape which, in the considered embodiment, is the one of the
tubular section that formed the object of the italian design application N. 21069
B/90 filed on 24.4.1990 by the same applicant. However it should be appreciated that
this shape must be considered non-limiting as, although it is a preferred one, it
could be different having nonetheless, according to the inventive concept of the present
invention, a plurality of recesses and contiguous protrusions suitable to engage respectively
with corresponding protrusions and recesses with which the fastening element according
to the present invention is provided.
[0015] The bedspring 10 is advantageously formed as a net with a first plurality of metal
wires 10a extending lengthwise parallel to each other and a second plurality of wires
10b extending parallel to each other in a transverse direction, which are welded to
each other in the points of intersection. The more external wires 10a and 10b of net
10 form the contour thereof and are connected to the fastening element 14 as shown
for wires 10a in Fig.2, wires 10b being connected in the same way.
[0016] Referring now also to Figs. 3 and 4 there is seen that the fastening element 14 is
formed, in a single body of predetermined length, by a first portion 16 for connection
with the peripheral wires 10a or 10b of net 10 and by a second portion 18 to be secured
on section 12.
[0017] The first portion 16 in particular is substantially U-shaped, one side of which extends
into the second portion 18 which is substantially C-shaped.
[0018] On the bottom of first portion 16 there is obtained a seat 20 for receiving wire
10a or 10b. In cross section it has a substantially circular shape extending along
an arc slightly greater than 180° thus holding firmly wire 10a or 10b.
[0019] The side 21 of portion 16, which is the upper one in operating conditions, has a
thickness decreasing towards its end edge 23 for helping the wire 10a or 10b to fit
into seat 20.
[0020] The second portion 18 of element 14 has such a shape to cover section 12 almost completely
in its upper part with respect to a horizontal median line and partially, for an angle
slightly less than 90°, in its lower part with respect to said median line.
[0021] In the considered embodiment section 12 has, symmetrically on its contour, four recesses
22 radiused with four corresponding adjacent protrusions 24 as described and illustrated
in the above cited italian design application. The internal surface of second portion
18 has correspondingly protrusions 26 and recesses 28 suited to engage respectively
into recesses 22 and with protrusions 24 of section 12. This coupling makes particularly
stable the securing of the fastening element 14 on section 12.
[0022] However it should be noted that section 12 and second portion 18 could have a number
of recesses and protrusions different from that above described, or have a different
arrangement of them, nonetheless attaining the same object.
[0023] Inside second portion 18 there is provided a means for securing the fastening element
14 to section 12 which, according to one of the characteristics of the element according
to this invention, is suitable to snap-fit in corresponding hollows formed in said
section 12 as more in detail hereunder described.
[0024] Said securing means, with reference also to Figs. 5 to 7a, comprises two radial appendixes
whose internal side 31 is curved. Each of them ends with a catch 32 directed towards
the outside of portions 18.
[0025] Between appendixes 30 there is provided a protrusion 34 having a height substantially
equal to the one of appendixes 30 and having a cross section which linearly decreases
towards its free end.
[0026] The whole formed by appendixes 30 and by protrusion 34 is designed to be inserted
into a hollow 36 of section 12. The side 31 of appendixes 30 and the catches 32 are
suited to snap engage with two opposite edges of said hollow 36 as it results from
the following description of the way in which the fastening element 14 is secured
to tubular section 12, with reference to Figs.5 to 7a.
[0027] In Figs. 5 and 5a the fastening element 14 and the tubular section 12 are represented
separated from each other and in particular in Fig. 5a there is seen that appendixes
30 are separated from the opposite walls of protrusion 34.
[0028] In Figs. 6 and 6a there is represented the initial stage of the securing of fastening
element 14 to tubular section 12 and in particular in Fig. 6a there is seen that catches
32 engage with two opposite edges 38 of hollow 36, inwardly folded and having an essentially
curved outline so as to create a slight narrowing of the cross section of hollow 36,
such to cause appendixes 30 to bend towards protrusion 34.
[0029] Figs. 7 and 7a represent the fastening element 14 and the tubular section 12 locked
to each other and in particular in Fig. 7a there is seen that catches 32, once disengaged
from said edges 38 of hollow 36, engage with the lower end of edges 38 with a substantially
snappy movement due to the fact that appendixes 30, thanks to the resilience of the
material the element 14 is made of, can return to their initial position having now
their sides 31 engaged with edges 38. The material of which the fastening element
14 is made is plastics and preferably said material is thermoplastic polypropylene.
[0030] The stability with which fastening element 14 is locked to tubular section 12 is
improved by the engagement of protrusion 34 between the two remaining opposite edges
40 of hollow 36 inwardly folded as shown in particular in Fig.2.
[0031] In Fig. 8 there is schematically represented in a perspective view a sofa supporting
plane employing staves 42. The element for their fastening to the frame or tubular
section 12 is now designated 14a because it differs from the element 14 for the fastening
of bedspring 10, merely in two details extraneous to the concepts of the present invention.
[0032] The fastening element 14a has in fact, instead of the U-folded portion 16, a hollow
appendix 44 adapted to form a seat for the end of stave 42. In addition portion 18
is provided with two groups of securing means, appendixes 30 and protrusion 34, instead
of only one, due to the fact that the fastening element 14a will be wider than the
fastening element 14.
[0033] In Figs.9 to 13a, analogous to Figs. 2 to 7a, there is represented the fastening
element 14a in operating conditions, in two perspective views and in the various operating
steps of its application to section 12. Its detailed description as well as that for
the application to section 12 are omitted being identical to those relating to the
fastening element 14. In Figs. 9 to 13a the same elements of Figs. 2 to 7a are indicated
with the same reference numbers.
[0034] From the above it clearly results which are the advantages deriving from using the
fastening element according to the present invention, the main of these advantages
being the readiness and simplicity of its application, the stability of locking the
same onto the frame and therefore of the whole supporting plane.
1. An element for fastening the supporting plane, formed either as a bedspring or as
a plurality of staves, to a chair-bed or sofa-bed frame, characterized by the fact
of consisting essentially of a first portion (16,44) suitable to be connected with
said bedspring (10) or stave (42) and of a second portion (18), integral with said
first portion (16,44), suitable to partially surround and to be applied on the tubular
section (12) forming the chair-bed or sofa-bed frame, said second portion having internally
means (30,32) for its securing to said section (12) and suited to be inserted into
a hollow (36) of the section (12) and to snap-fit with the edges (38) thereof.
2. A fastening element according to claim 1 characterized by the fact that said means
for securing the second portion (18) to the tubular section (12) comprises at least
a pair of appendixes (30) radially extending inside said portion (18), and provided
at their end with a catch (32), the distance between said appendixes being slightly
greater than the width of the hollow (36) thus causing, during the insertion of said
appendixes (30) into the hollow (36), at first a mutual approaching thereof and, once
the insertion is accomplished, their moving apart with simultaneous snap engagement
of the catches (32) with the edges (38) of the hollow (36).
3. A fastening element according to claim 2 characterized by the fact that the edges
(38) of the hollow (36) with which the catches (32) engage are bent inside the tubular
section (12) with a substantially curved shape.
4. A fastening element according to claim 2 characterized by the fact that between the
appendixes (30) there is provided a protrusion (34) with cross section decreasing
towards its free end thus allowing the temporary approaching of the appendixes (30)
during their insertion into the hollow (36).
5. A fastening element according to claim 1 characterized by the fact that the second
portion (18) is internally provided with protrusions (26) and recesses (28) suitable
to engage respectively with recesses (22) and protrusions (24) of the tubular section
(12).
6. A fastening element according to claim 3 characterized by the fact that, once the
insertion of the appendixes (30) into the hollow (36) is accomplished, the protrusion
(34) of the second portion (18) engages with the two remaining opposite edges (40)
of the hollow (36).
7. A fastening element according to claim 1 characterized by the fact that the first
portion (16) has a substantially U-shape in the bottom of which there is formed a
seat (20) suitable to receive a peripheral wire (10a or 10b) of the bedspring (10).
8. A fastening element according to claim 7 characterized by the fact that the seat (20)
has, in cross section, an essentially circular outline extending for an arc slightly
greater than 180°.
9. A fastening element according to claim 7 characterized by the fact that the side (21)
of the first portion (16), defining the passage for the wire (10a or 10b) of the bedspring
(10) for its insertion into the seat (20) has an outline with decreasing thickness
towards its free edge.
10. A fastening element according to claim 2 and 3 characterized by the fact that the
external side of the appendixes (30) has a shape complementary with respect to that
of the bent edges (38) of the hollow (36).