Note: Descriptions are shown in the official language in which they were submitted.
1
SYSTEM AND ROLL-UP DOOR FOR MAINTAINING A
DOWNWARD TENSION ON A ROLL-UP DOOR CURTAIN
TECHNICAL FIELD
[0001] The present disclosure relates to the field of door
systems.
More specifically, the present disclosure relates to a system for maintaining
a
downward tension on a roll-up door curtain and to a roll-up door integrating
the
system.
BACKGROUND
[0002] Roll-up doors offer wide flexibility in terms of sizes and
the
capability of undergoing large numbers of fast opening and closing cycles in a
single day. They are used, predominantly in commercial and industrial
applications. These doors usually comprise a large curtain made of a flexible
material, for example rubber, supported by guides on each side of a door
frame. Figure 1 (prior art) is an example of a releasable roll-up door system,
as
disclosed in US Patent Application Publication Number 2016/0177624 Al, to
Palencia et al., published on June 23, 2016. A roll-up door system 100
comprises a curtain 102, a pair of lateral, vertical door guides 104
configured
to hold sides of the curtain 102 when lowered, and a curtain riser, generally
at
111. The curtain riser 111 includes a standard motorized drive 108 operably
connected to a roller 110 on which the curtain 102 can be rolled when raised.
The roller 110 may for example comprise a hollow tube, a rod, or the like, and
generally has a circular cross-section to facilitate rolling of the curtain
102. The
curtain 102 may terminate on a lower horizontal bar 112. A controller 128
controls turning on and off the motorized drive 108 in distinct directions for
raising and lowering the curtain 102.
[0003] Because roll-up doors may be very large, they may
withstand
excessive wind loads leading to ripping or tearing of the curtain, or to
breakage
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of the guides or door frame. An example of a rollable door and rollable door
guiding system having a deformable guide is disclosed in US Patent Number
9,416,589 B2, to McTavish et al., issued on August 16, 2016. Figure 2 (prior
art) is a cross-sectional view of the door guide and edge of the curtain of
Figure 1. The vertical door guide 104 comprises a longitudinal rear base wall
50 extending along a height of the vertical door guide 104 when viewed in the
orientation as shown on Figure 1. Holes such as 52, optionally threaded, are
provided to allow installation of the vertical door guide 104 on a doorway
frame
using bolts (not shown). A pair of longitudinal, spaced apart and parallel or
substantially parallel wall sections 54 and 56 extends from the longitudinal
base wall 50 to define a cavity 58 between the wall sections 54 and 56. In a
particular embodiment, the wall section 54 has a thinner cross-section 55 when
compared to a cross-section 57 of the wall section 56. Consequently, while
both wall sections 54 and 56 are deformable, the wall section 54 tends to flex
with greater amplitude than the wall section 56 when a force is applied to the
vertical door guide 104. On the front side of the vertical door guide 104, the
wall portion 56 is bent a first time at 90 degrees to form a longitudinal
front wall
portion 62. The wall portion 56 is bent a second time at 90 degrees to define
a
wall portion parallel to the wall portions 54 and 56 and defining an inner
longitudinal planar face 66, parallel to both the wall portions 54 and 56, and
an
inner longitudinal edge 68 at an extremity of the inner longitudinal planar
face
66. On the front side thereof, the wall portion 54 is bent inwardly at an
obtuse
angle (see 70) to form an angular longitudinal wall 72 with a free
longitudinal
edge 74.
[0004] The
vertical door guide 104 is sized to accommodate
dimensions of a vertical side strip 5 attached on a side edge of the curtain
102.
The side strip 5 comprises a proximate longitudinal portion 12, which is U-
shaped in cross section for attachment to an edge of the curtain 102, and a
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distal longitudinal end-section for sliding into the vertical door guide 104.
Opposite from the proximate longitudinal portion 12 of the vertical side strip
5
are, on one side, a first longitudinal rib 22 and, on another side, a shifted
wall
section 24. The shifted wall section 24 forms a free edge of the vertical side
strip 5. The shifted wall section 24 also defines a second longitudinal rib 28
with a sloping wall 30 on the corresponding side of the vertical side strip 5.
[0005] The first longitudinal rib 22 is generally trapezoidal in
cross
section and is positioned on the side of the vertical side strip 5 opposite
the
second longitudinal rib 28. Also, the first longitudinal rib 22 is laterally
shifted
inwardly with respect to the second longitudinal rib 28.
[0006] The vertical side strip 5 defines a first planar surface 6
between the proximate U-shaped longitudinal portion 12 and a shifted wall
section 24. The inner longitudinal planar face 66 of the vertical door guide
104
is a mating surface for the first planar surface 6. The first planar surface 6
can
rest or slide on the inner longitudinal planar face 66. The inner longitudinal
edge 68 of the vertical door guide 104 is a mating surface for a sloping wall
30
of the second longitudinal rib 28. The sloping wall 30 can rest or slide on
the
inner longitudinal edge 68 to maintain the vertical side strip 5 into the
cavity 58
of the vertical door guide 104.
[0007] In the same manner, the vertical side strip 5 defines a
second
planar surface 7 opposite the first planar surface 6 between the proximate U-
shaped longitudinal portion 12 and the generally trapezoidal first
longitudinal
rib 22. The second planar surface 7 slides onto the longitudinal edge 74 while
a sloping wall 8 of the generally trapezoidal first longitudinal rib 22 slides
on
the inner surface of the angular longitudinal wall 72 to maintain the vertical
side
strip 5 into the cavity 58 of the vertical door guide 104.
[0008] When assembled, the vertical side strip 5 attached to the
curtain 102 is movable or slidable longitudinally in the vertical door guide
104
as the curtain 102 is raised or lowered during use thereof. Together, the
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vertical side strip 5 and the vertical door guide 104 form a guiding system
for a
roll-up door having the curtain 102. For this, the longitudinal edge 74
defines
with the inner longitudinal planar face 66 a longitudinal slot to receive the
vertical side strip 5 between the proximate U-shaped longitudinal portion 12
and a first longitudinal rib 22. Embodiments of the guiding system may
comprise two opposed vertical door guides 104 on either sides of the curtain
102. In such cases, two symmetrically mounted vertical side strips 5 attached
to opposed vertical edges of the curtain 102 move or slide within
corresponding vertical door guides 104.
[0009] In normal operation, the vertical door guide 104 has a
cross-
section shaped substantially as shown on Figure 2. As the curtain 102 of the
roll-up door system 100 is raised or lowered, the vertical side strip 5 slides
within the vertical door guide 104. More specifically, the first planar
surface 6
slides on the inner longitudinal planar face 66 with the sloping wall 30 of
the
shifted wall section 24 sliding on the inner longitudinal edge 68 to retain
the
vertical side strip 5 into the cavity 58 of the vertical door guide 104. Also,
the
second planar surface 7 opposite the first planar surface 6 slides onto the
longitudinal edge 74 while the sloping wall 8 of the generally trapezoidal
first
longitudinal rib 22 mates with an inner surface 9 of the angular longitudinal
wall
72, sliding or resting thereon to maintain the vertical side strip 5 into the
cavity
58 of the vertical door guide 104.
[0010] However, when a wind load or impact causing a load
exceeding a predetermined threshold is applied upon the curtain 102, this load
being transmitted to the vertical side strip 5, such wind load or impact will
cause deformation of the vertical door guide 104, in which the wall portions
54
and 56 separate from each other at the front of the vertical door guide 104 to
thereby spread apart the longitudinal edge 74 and the inner longitudinal
planar
face 66, thereby widening the longitudinal slot defined between them. Because
the cross-section 55 of the wall portion 54 is thinner than the cross-section
57
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of the wall portion 56, the wall portion 54 tends to undergo a greater
deformation than the wall portion 56 when a force is applied to the vertical
door
guide 104. Widening of the longitudinal slot in turn allows the generally
trapezoidal first longitudinal rib 22, at first, and then the shifted wall
section 24,
to pass through the longitudinal slot and release the vertical side strip 5
from
the vertical door guide 104 with little, if any, damage to the curtain 102 or
the
vertical door guide 104. Notably, the obtuse angle 70 allows the sloping wall
8
to slide on the angular longitudinal wall 72 with relative ease.
[0011] While the roll-up door system 100 is very efficient in
allowing
release of the door curtain 102 in case of impact from a vehicle or in case of
excessive wind, improvements are still desired in some applications. In
particular but without limitation, when the roll-up door system 100 is used in
underground mines, forced ventilation oftentimes causes very heavy pressure
being applied on the curtain 102. For example, an 8-foot high by 12-foot wide
curtain 102 may be exposed to nearly 3000 pounds of pressure. When closing
the door, as the pressure builds up on unrolled parts of the curtain 102, its
edges may tend to wave and fail to freely move within the vertical door guides
104. As the motorized drive 108 continues rotating the roller 110, the curtain
102 may remain stuck about the roller 102. Even without waving of the edges
of the curtain 102, because of the ventilation, there have been events when
the
heavy pressure that built on the curtain 102 as it rolled down caused it to
blow
out of its guides 104.
[0012] This problem can cause heavy damages in roll-up door
systems that are not configured to release their curtains in case of high wind
or
impact. Blow out of the curtain in such roll-up door systems are very serious
events in which door guides, curtains or even door frames may be damaged.
[0013] Therefore, there is a need for a roll-up door system
capable of
preventing damages to roll-up door systems under excessive wind load
situations.
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SUMMARY
[0014] According to the present disclosure, there is provided a
roll-up
door comprising a flexible curtain, a horizontal roller on which the flexible
curtain can be rolled when raised, and a bottom bar extending on a bottom of
the flexible curtain. The roll-up door also comprises, on each of its lateral
sides, a tensioning weight, an upper pulley mounted above the horizontal
roller, a lower pulley mounted near a bottom of the roll-up door, and a cable.
The cable has a first end attached to the tensioning weight and a second end
opposite from the first end, the second end being attached to a respective
side
of the bottom bar. A first section of the cable proximate to the first end
passes
around the upper pulley and a second section of the cable proximate to the
second end passes around the lower pulley.
[0015] According to the present disclosure, there is also provided
a
system for maintaining a downward tension on a roll-up door curtain, the roll-
up door curtain having a bottom bar extending on its lower end. Each lateral
side of the system comprises a tensioning weight, an upper pulley mountable
above a top of the roll-up door curtain, a lower pulley mountable near a
position of the bottom bar when the roll-up door curtain is fully lowered, and
a
cable. The cable has a first end attached to the tensioning weight and a
second end opposite from the first end, the second end being attached to a
respective side of the bottom bar. A first section of the cable proximate to
the
first end passes around the upper pulley and a second section of the cable
proximate to the second end passes around the lower pulley.
[0016] The foregoing and other features will become more apparent
upon reading of the following non-restrictive description of illustrative
embodiments thereof, given by way of example only with reference to the
accompanying drawings.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0017] Embodiments of the disclosure will be described by way of
example only with reference to the accompanying drawings, in which:
[0018] Figure 1 (prior art) is an example of a releasable roll-up
door
system;
[0019] Figure 2 (prior art) is a cross-sectional view of the door
guide
and edge of the curtain of Figure 1;
[0020] Figure 3 is a schematic rear elevation view of a roll-up
door
according to an embodiment;
[0021] Figure 4 is a schematic top plan view of the roll-up door of
Figure 3;
[0022] Figure 5 is a rear perspective view of the roll-up door of
Figure
3;
[0023] Figure 6 shows details of an upper pulley and cable of the
roll-
up door of Figure 3;
[0024] Figure 7 shows details of a lower pulley and cable of the
roll-
up door of Figure 3;
[0025] Figure 8 shows details of an attachment point of the cable
to
the bottom bar of the roll-up door of Figure 3; and
[0026] Figure 9 is a side elevation view showing details of a
tensioning weight of the roll-up door of Figure 3.
DETAILED DESCRIPTION
[0027] Like numerals represent like features on the various
drawings.
[0028] Various aspects of the present disclosure generally address
one or more of the problems related to lowering of roll-up doors under
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excessive wind load situations.
[0029] According to the present disclosure, a downward tension is
applied at the bottom of a flexible curtain of a roll-up door. To this end,
tensioning weights are provided on each side of the flexible curtain and are
connected via cables and pulleys to a bottom bar fixedly attached at the
bottom of the flexible curtain. The tensioning weights are raised and lowered
with the flexible curtain while maintaining the downward tension. Problems
related to wind load on the flexible curtain are alleviated in that the
downward
tension prevents, at least to a large extent, problems related to waving of
edges of the flexible curtain within their lateral guides. The downward
tension
also tends to maintain the edges of the flexible curtain in their lateral
guides,
preventing blow out of the flexible curtain.
[0030] It may be observed that the tensioning weights do not
function
in the same manner as so-called counterweights that are sometimes used to
facilitate rising a door curtain by applying an upward force to counteract the
weight of the door curtain itself. The tensioning weights of the present
system
actually add to the effort required to raise the door curtain.
[0031] Referring now to the drawings, Figure 3 is a schematic rear
elevation view of a roll-up door according to an embodiment. Figure 4 is a
schematic top plan view of the roll-up door of Figure 3. Referring at once to
Figures 3 and 4, a roll-up door 200 comprises a flexible curtain 202, which
may
also be called a roll-up door curtain. The flexible curtain 202 has two sides
204
and 206, a top 208 and a bottom 210. At a top of the roll-up door 200 is a
horizontal roller 212 on which the flexible curtain 202 can be rolled when
raised. The flexible curtain 202 is illustrated in a partially lowered
position on
Figure 2. A bottom bar 214 extends on the bottom 210 of the flexible curtain
202. The roll-up door 200 has two (2) lateral sides. A vertical door guide 216
adapted to slidably receive a respective side edge (similar to vertical side
strip
of Figure 2) of the flexible curtain 202 may be present on each lateral side
of
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the roll-up door 200. The vertical door guides 216 may optionally be
configured
to release the respective side edge of the flexible curtain 202 upon
application
on the flexible curtain 202 of a force exceeding a predetermined threshold.
[0032] A tensioning weight 218, an upper pulley 220, a lower pulley
222 and a cable 224 are also located on each lateral side of the roll-up door
200. The upper pulleys 220 are mounted above the horizontal roller 212. The
lower pulleys 222 are mounted near a bottom of the roll-up door 200, near a
position of the bottom bar 214 when the flexible curtain 202 is fully lowered.
[0033] On each lateral side of the roll-up door 200, the cable 224
has
a first end 226 attached to the tensioning weight 218. A first section 228 of
the
cable 222 proximate to the first end 226 passes around the upper pulley 220.
The cable 224 has a second end 230 opposite from the first end 226. The
second end 230 is attached to respective attachment points 232 of the bottom
bar 214. A second section 236 of the cable 224 proximate to the second end
230 passes around the lower pulley 222.
[0034] As best seen on Figure 4, in an embodiment, the tensioning
weights 218, the vertical door guides 216, the upper pulleys 220, the lower
pulleys 220 and the flexible curtain 202 are generally aligned within a common
vertical plane, schematically represented by a dashed line 238. Bottom ends
240 of the tensioning weights 218 as shown on Figure 3 are positioned
substantially at a level of the bottom bar 214 in relation to the ground 242;
the
tensioning weights 218 could be positioned somewhat higher in some
embodiments. An overall length of the cables 224 is selected so that the
bottom ends 240 of the tensioning weights 218 do not reach the ground 242
before the flexible curtain 202 is fully lowered, the bottom bar 214 resting
on
the ground 242. A longer length of the cables 224 may be used if apertures
(not shown) are dug in the ground 242 to freely receive the bottom ends 240 of
the tensioning weights 218. A shorter length of the cables 224 may keep the
bottom ends 240 of the tensioning weights 218 floating above the ground 242
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when the flexible curtain 202 is fully lowered, but the cables 224 should be
sufficiently long to prevent a top 234 of the tensioning weights 218 from
colliding with the upper pulleys 220 when the flexible curtain 202 is fully
raised.
[0035] In the shown embodiment, the upper pulleys 220 have
rotational axes 244 normal to the common vertical plane 228 and are each
substantially positioned above outer edges 246 of respective vertical door
guides 216 opposite from the curtain 202. The lower pulleys 222 have
rotational axes 248 normal to the common vertical plane 238 and are each
positioned within respective vertical door guides 216.
[0036] Further details of the roll-up door 200 are depicted in
Figures 5
to 9, of which Figure 5 is a rear perspective view of the roll-up door of
Figure 3,
Figure 6 shows details of an upper pulley and cable of the roll-up door of
Figure 3, Figure 7 shows details of a lower pulley and cable of the roll-up
door
of Figure 3, Figure 8 shows details of an attachment point of the cable to the
bottom bar of the roll-up door of Figure 3, and Figure 9 is a side elevation
view
showing details of a tensioning weight of the roll-up door of Figure 3.
Referring
at once to Figures 3 to 9, a vertical hollow enclosure 250 is located on each
lateral side of the roll-up door 200. For safety reasons, the tensioning
weights
218 are placed within respective vertical hollow enclosures 250. The
tensioning weights 218 are each sized and configured to freely move up and
down within a respective vertical hollow enclosure 250. In the shown
embodiments, each of the vertical hollow enclosure 250 is cylindrical and thus
has a circular cross-section. The tensioning weights 218 are also cylindrical
in
shape. Other matching shapes of the vertical hollow enclosures 250 and of the
tensioning weights 218 may also be contemplated.
[0037] In an embodiment, the vertical door guides 216 are each
formed of a pair of separable vertical members 252 and 254. The vertical
members 252 and 254 are connected via a plurality of hinges 256 distributed
along their height. Opening the vertical door guides 216 by separating the
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vertical members 252 and 254 allows easy access to the lower pulleys 222, to
the cable 224 and facilitates attachment of its end 230 to the attachment
points
232 of the bottom bar 214. The vertical members 254 are fixedly attached to a
frame on which the roll-up door 200 is mounted. In operation, the vertical
members 252 are moved toward the vertical members 254 in order to form
slots receiving the sides 204 and 206 of the flexible curtain 202. The
vertical
members 252 and 254 may be joined by use of bolts (not shown) distributed
along their height.
[0038] As shown on Figure 9, the bottom end 240 of the tensioning
weight 218 is substantially at a same height as the bottom bar 214, with
respect to the ground 242.
[0039] A motorized drive 258 is operably connected to the
horizontal
roller 212, for example via a chain 260 driving a sprocket 264 mounted to an
external shaft 264 of the horizontal roller 212. The motorized drive 258 is
operable to raise and lower the flexible curtain 202. The downward tension on
the flexible curtain 202 caused by the tensioning weights 218 adds to the
effort
of the motorized drive 258 when raising the flexible curtain 202. This added
effort can be compensated by proper dimensioning of a ratio between a
sprocket (not shown) of the motorized drive 258 and the sprocket 264 or by
proper selection of a gear ratio or of an electric motor in the motorized
drive
258. When lowering the flexible curtain 202, as wind pressure may build on the
flexible curtain 202, the downward tension provided at its bottom 210 by the
tensioning weights 218 tends to prevent waving of the sides 204 and 206 of
the flexible curtain 202, thereby preventing that the flexible curtain 202
remains
stuck within the vertical door guides 216. This downward tension also limits
the
risk of the flexible curtain 202 being released from the vertical door guides
216
because of the wind pressure. In an embodiment, a weight of each tensioning
weight 218 is substantially equal to a quarter of a weight of the flexible
curtain
202. Other ratios between the respective weights of the flexible curtain 202
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and of the tensioning weights 218 are also contemplated. These ratios may be
selected in view of expected wind loads on the flexible curtain 202.
[0040] Those of ordinary skill in the art will realize that the
description
of the door and of the system for maintaining a downward tension on a roll-up
door curtain are illustrative only and are not intended to be in any way
limiting.
Other embodiments will readily suggest themselves to such persons with
ordinary skill in the art having the benefit of the present disclosure.
Furthermore, the disclosed door and system may be customized to offer
valuable solutions to existing needs and problems of limiting damages to
buildings under excessive load situations.
[0041] In the interest of clarity, not all of the routine features
of the
implementations of the door and system are shown and described. It will, of
course, be appreciated that in the development of any such actual
implementation of the door and system, numerous implementation-specific
decisions may need to be made in order to achieve the developer's specific
goals, such as compliance with application-, system-, and business-related
constraints, and that these specific goals will vary from one implementation
to
another and from one developer to another. Moreover, it will be appreciated
that a development effort might be complex and time-consuming, but would
nevertheless be a routine undertaking of engineering for those of ordinary
skill
in the field of door systems having the benefit of the present disclosure.
[0042] Although the present disclosure has been described
hereinabove by way of non-restrictive, illustrative embodiments thereof, these
embodiments may be modified at will within the scope of the appended claims
without departing from the spirit and nature of the present disclosure.
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