Field of the Invention
The present invention relates to the technical field concerning
roll-up curtains to be applied to windows and the like, in order to shade, protect
Background of the Invention
The roll-up curtains are usually rolled up on a roller,
which is rotatably carried on a horizontal axis inside a suitable casing situated
at top of the window.
The axial rotation of the roller determines rolling and
unrolling of the curtain.
According to a known solution, the roll-up curtains are
operated manually during both rolling and unrolling.
For this purpose, the head of the roller has a pulley featuring
a groove, which engages with an operating chain.
One of the drawbacks of this type of roll-up curtains is
the risk of falling during unrolling, i.e. a too quick descent of the curtain can
occur due to its weight.
It is to be particularly noted that the falling speed of
the curtain increases rapidly during unrolling.
Obviously, this drawback is felt stronger in the special
case of relatively heavy curtains.
According to another solution, the roll-up curtains are
equipped with a safety device with elastic means situated inside the roller and
fastened thereto to facilitate the curtain rolling up.
The curtain unrolling rotation, carried out by acting directly
thereon, determines torsion of the elastic means, so that the consequent elastic
reaction can be used for rolling up again the curtain.
The elastic means are fastened, at one end, to the roller
and at the other end, to a stationary support structure, so that they are stressed
in accordance with the curtain unrolling.
To avoid undulations, possible in particular conditions,
of the elastic means, these elastic means are fastened at one end to a movable element,
which moves axially inside the roller, and are driven into rotation therealong.
For instance, the European Patent EP 0900314 describes
improved elastic means, which return a gradual elastic reaction during the curtain
The improved elastic means include a plurality of helical
springs aimed at rolling the curtain up on a respective roller.
The coil springs are fastened to a common support, keyed
to the roller, and to respective support and constraint elements, geometrically
fastened to the above roller.
The above described support devices fulfill also the additional
task of contrasting the curtain descent, but obviously, they themselves cannot solve
the drawback of a curtain possible fall during unrolling.
Patent publication US-A-1.416.071 discloses a friction
device, in which a curtain is rolled up about a tubular roller rotatably carried
by a horizontal axle. A threaded shaft is situated inside the roller and a body,
with a threaded hole, slides along the shaft and within the roller. A spring element
pushes on a side of the body so as to create a friction effect in relation to the
rotation of the roller.
Summary of the Invention
The object of the present invention is to propose a friction
device which avoids possible fall of the curtain during unrolling, very functional
and simple to manufacture, as well as to use, and which is versatile and can be
used with different types of roll-up curtains.
A further object of the present invention is to propose
a device which is associated to a curtain operated by a chain and which is not damaged
if the curtain is operated directly manually.
A yet further object of the present invention is to propose
a universal device, i.e. a device which can be connected, during the installation
or in any subsequent moment, to any end of the curtain, so as to be connected to
the operating chain situated either on the right or on the left of the latter.
A still further object of the present invention is to propose
a device which not only achieves the previous objects, but is also cheap and includes
components such as to render the assembly easy.
A yet further object of the present invention is to propose
a device which can be assembled in one piece, so that it can easily be mounted in
a related curtain.
A still further object of the present invention is to propose
a device which, when associated to the curtain equipped with support elastic means,
balances in a simple way the operation of the curtain during the unrolling and rolling
The above mentioned objects are obtained in accordance
with the contents of the claims, by means of a friction device for roll-up curtains
and the like, including a tubular roller, on which the curtain rolls up, and which
is rotatably carried on a horizontal axis, characterized in that it includes a threaded
shaft, situated axially inside said roller and connected to the roller by interposition
of an angular speed reducer group; a body mounted sliding axially inside said roller
and screw-coupled with said threaded shaft, so as to translate axially due to the
shaft rotation during unrolling or rolling up of said curtain on said roller; at
least one elastic member which is tightened, on the opposite ends, between the abutment
means and a surface of said body, to determine, due to the pressure or counter-thrust
to which the elastic member is subjected, a friction effect, which varies as a function
of the rotation direction of said roller.
Brief Description of the Drawings
The characteristic features of the present invention will
be pointed out in the following description of a preferred, but not sole embodiment,
with reference to the enclosed drawings, in which:
Best Modes of Carrying out the Invention
- Figure 1 is a schematic view of a roll-up curtain in rolling up configuration;
- Figure 2 is a schematic view of the roll-up curtain in unrolling configuration;
- Figure 3 is a longitudinal section view of a head of the roller of the roll-up
curtain, corresponding to the portion A of Figure 1;
- Figure 3A shows a variant of what is shown in Figure 3;
- Figure 4 is a cross-section view of the roller taken along the plane IV-IV of
- Figure 5 is a longitudinal section view of a head of the roller according to
a different embodiment;
- Figure 6 is a cross-section view taken along the plane VI-VI of Figure 3;
- Figure 7 is a cross-section view taken along the plane VII-VII of Figure 5;
- Figures 8 and 9 are longitudinal section views of another embodiment of the
head of the roller, in different operation steps;
- Figure 10 is the same longitudinal section view of a variant of the head of
With reference to the above figures, the reference numeral
1 indicates the tubular roller, on which the curtain 2 rolls up, which is known
from the prior art.
The roller 1 is rotatably supported on a horizontal axis,
by respective supports 3, which are integral with the stationary structure.
One end of the roller 1 abuts against a speed reducer connection
group indicated as a whole with 4.
More in detail, the roller 1 couples in a prismatic way
with a cup-like element 5, which consequently rotates together with the roller 1.
A head 6, introduced into the cavity formed by the cup-like
element 5, is rigidly fastened to the support 3 of the stationary structure by coupling
with a prismatic appendix 7 of the element 5.
As described in detail in the European Patent EP 0900314,
the head 6 features an axial toothed protrusion, which meshes with a plurality of
planetary toothed wheels carried by a planetary wheel carrying member 8 and engages
with a circumference toothing made on the inner surface of the cup-like element
5, so as to form a planetary gear.
The planetary wheel carrying member 8 is rigidly fastened
to a threaded shaft 9, extending axially inside the roller 1.
The shaft 9 is a part of a friction device, indicated as
a whole with 10, inserted into the roller 1.
The friction device 10 includes a cylindrical body 11,
which features axially a threaded hole aimed at coupling with the shaft 9.
The cylindrical body 11 rotates together with the roller
1, but it can translate axially with respect thereto.
One end of an elastic member 12 acts on a surface of the
cylindrical body 11, whereas the opposite end of the elastic member 12 abuts against
a nut 13 screwed onto the shaft 9.
By acting on the nut 13 it is possible to adjust the pre-loading
of the elastic member 12, consequently the elastic member 12 is subjected to pressure
According to the embodiment shown in Figures 3 and 4, which
is not claimed, the elastic member 12 preferably includes a helical leaf spring,
obtained e.g. beginning from a cylindrical tubular element of e.g. steel or other
material fulfilling the same elastic function, in which a helical incision is made
by mechanical cutting.
The spring obtained according to this embodiment compresses
without deforming which assures a long duration. This type of helical leaf spring
is particularly suitable for curtains which are heavy and/or of considerable dimensions.
As an alternative to the above described type of spring,
it is possible to use a normal commercial spring, e.g. a helical spring (see Figure
3A), particularly indicated for currently used curtains: the material used is, e.g.
steel kind or other material fulfilling the same elastic function.
The working of the device will be described in the following.
When the curtain 2 is pulled, by acting directly thereon
by e.g. a lower ring 20, the roller 1 is made to rotate on the supports 3.
The roller 1 drives the shaft 9, inserted axially therein,
into rotation with an angular travels suitably reduced by the reducer group 4 which
acts as an intermediary.
In other words, the shaft 9 rotates with a relatively lower
extension with respect to the roller 1.
The relative rotation of the shaft 9 with respect to the
roller 1 determines an axial translation of the cylinder 11 of the friction group
10, whose rotation with respect to the same roller 1 is prevented by suitable prismatic
coupling means, e.g. a pair of opposite teeth 14, guided in corresponding inner
grooves of the roller 1, as seen in Figure 6.
The axial translation of the cylinder 11 causes a progressive
change of the length K of the spring 12, which is stationary at the abutment on
the nut 13, and consequently, a progressive change of the compression of the spring
Accordingly, the initial compression of the spring can
be suitably adjusted, by registering the position of the nut 13.
Obviously, the bigger or smaller compression of the spring
12 changes the elastic thrust action exerted on the cylinder 11 and consequently,
avoids the fall of the curtain during the unrolling step.
Practically, during the curtain 2 unrolling, the compression
of the spring 12 is progressively increased and consequently, also the friction
effect is increased.
On the contrary, during the curtain 2 rolling up, the spring
12 is progressively released and consequently, the friction effect is reduced.
This allows especially to contrast in a suitable way the
curtain 2 unrolling, with an increasing braking effect due to the friction, so as
to prevent the curtain 2 fall during the unrolling step.
On the contrary, the braking effect is reduced progressively
during the curtain 2 rolling up.
As a consequence, the rapid fall of the curtain is advantageously
prevented, even if the curtain is relatively heavy.
Figure 5 shows a different embodiment, also not claimed,
of the friction device, used in particular with roll-up curtains operated by a chain
or other similar means.
The chain engages with a shaped groove of a pulley 15 made
on the outer edge of the cup-like element 5 of the reducer group 4.
According to this solution, the cylinder 11 is acted upon
by an elastic member 12 formed in the shown example by a pair of helical springs
12a and 12b which push on an intermediate disc 16.
The elastic member 12 abuts against the adjustment nut
13 screwed on the shaft 9, against which an additional cylindrical body 17 goes
in abutment, stressed by a relative elastic member 18, which on its turn goes in
abutment against a further adjustment nut 19.
The additional cylinder 17 is not screwed on the threaded
shaft 9, but the latter passes freely through an axial hole of suitable diameter
made in the cylinder 17 (see also Figure 7).
Therefore, the rotation of the shaft 9 due to the rotation
of the roller 1 during the curtain 2 rolling up and unrolling, determines only the
translation of the cylinder 11, as described previously.
The additional cylinder 17, on which the spring 18 acts,
determines a friction effect of constant value, adjustable in pre-loading step by
the nut 19.
According to the invention, Figures 8 and 9 show another
embodiment of the friction device 10, in which the elastic member 12 is advantageously
formed by a plurality of balls 21, made of elastic material, e.g. neoprene rubber
or another elastic material.
The balls 21, suitably bored along a diametric axis, are
put on the shaft 9 of the friction device, close to each other.
The balls 21 of elastic material are clamped between a
pair of abutment disks 22, 13, which are supported respectively by the cylinder
11 and by the planetary wheel carrying member 8 connected to the reducer connection
group 4: also in this case the elastic means, i.e. the balls 21, are subjected to
pressure or counter-thrust.
In rest position, i.e. when the curtain 2 is rolled up,
the balls 21 are not compressed and consequently do not perform braking action (Figure
On the contrary, during the unrolling of the curtain 2,
the balls 21 are progressively compressed due to the axial translation of the cylinder
11, as seen in Figure 9.
Obviously, the compression of the balls 21 increases progressively
the elastic thrust performed on the cylinder 11 and consequently also the friction
effect performed between the contacting surfaces.
Obviously, the number of the balls 21 can suitably vary
in relation to the dimensions of the roll-up curtain.
The balls 21 can also have different elastic reaction characteristics,
due to e.g. different hardness of the elastic material of which they are made. Also,
balls with different diameters can be used. Balls 21 with different elastic reaction
characteristics can be also included in a definite series of balls 21.
For instance, the braking effect of the friction device
can be correspondingly changed by substituting one or more balls 21 of the series
with others of different characteristics and/or different diameters.
In practical terms, it allows to meet a wide range of needs.
The balls 21 of elastic material can have a flattened outline
24, which avoids any interference with the inner surface of the roller 1 while being
compressed (see Figure 10).
The proposed device which uses the balls 21 is particularly
designed for economic curtains.
Consequently, the proposed friction device fulfills the
object to avoid the fall of the roll-up curtain during the unrolling step, even
if the curtain is relatively heavy.
A prerogative of the proposed friction device derives from
the fact that it performs an increasing braking action during the curtain unrolling,
so as to contrast efficiently the corresponding increase of the curtain descent
speed and, consequently creates substantially uniform operation conditions.
It is also to be pointed out that the friction device can
be advantageously used with roll-up curtains equipped with return elastic means,
as well as with roll-up curtains operated manually, so that its use is universal.
In case of curtains operated by chain, the proposed device
is not damaged if the operator acts manually on the curtains.
The particular conformation of the proposed solution makes
the corresponding device universal, i.e. valid for curtains with operating chain
situated on the left as well as on the right.