Note: Descriptions are shown in the official language in which they were submitted.
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PLUG WITH SAFETY MEANS FOR USE WITH COUNTERBALANCING
SYSTEMS OF GARAGE DOORS AND THE LIKE
Field of the invention
The present invention relates to a plug, also known as a "collar" or an
"anchor", such as the ones used for operatively connecting torsion springs to
overhead shafts of counterbalancing mechanisms used for garage doors and the
like, in order to allow a torque transfer between the torsion spring and the
overhead shaft so as to counterbalance such cable operated doors. More
particularly, the present invention relates to a plug comprising safety means
which
interlock with a mating part of the counterbalancing mechanism when tension is
applied to the torsional spring, so as to prevent the plug from being readily
removed therefrom in order to avoid serious injuries to unexperienced or
inadvertent users tampering with the plug when tension is still present in the
torsional spring.
Backaround of the invention
It is known in the art that large, vertical, cable operated doors, such as
commercial and residential sectional garage doors, usually require
counterbalancing mechanisms to counterbalance the weight of the door in order
to
decrease the force required to open the door and also facilitate its closing
from a
raised to a lowered position. Large sectional garage doors used in commercial
and
residential applications may be manually or power operated. In either case,
but
particularly for manually operated doors, counterbalancing mechanisms have
been
used for many years to counterbalance the weight of the door and control its
opening and closing movements so that one person can easily control the
operation of the door. Counterbalancing mechanisms are also advantageous for
power operated overhead doors since they reduce the power requirements
needed for the motor and they lower the structural strength required for the
opening and closing mechanism of the door. In other words, lighter weight,
lower
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cost, door controlling mechanisms may be used if a counterbalancing mechanism
is connected to the door to assist it in its opening and closing movements.
Furthermore, the provision of a counterbalancing mechanism minimizes the
chance of a rapid and uncontrolled closing of the door in the event of failure
of one
of the components of the door controlling mechanism, which can result in
personal
injury or damage to property.
It is also known in the art that a widely used type of counterbalancing
mechanism generally comprises a pair of spaced apart cable drums connected to
flexible cables, each cable being in turn connected to a lower opposite side
edge
of the garage door. The cable drums are usually mounted on an overhead shaft
which is supported above the door opening and is connected to one or more
torsion springs which are each fixed to the shaft at one end, and secured to
the
wall at the other end, so that the cable drums are biased to rotate in a
direction
which winds the cables onto the drums and counteracts the weight of the door
connected to the cables. Generally, conventional counterbalancing mechanisms
include two torsion springs which are coaxially mounted onto the overhead
shaft
and which are opposed to one another. Furthermore, the torsion springs are
adjusted by applying tension therein to properly balance the weight of the
door so
that minimal opening and closing efforts are required, either manually or when
motor controlled. The two drums which are used for winding the cables are
usually
fastened at each opposite end of the overhead shaft and are fixed to the same
by
means of screws, whose respective ends are in contact with the shaft and exert
pressure thereon.
It is also known in the art that conventional, low cost adjustment devices
used for the above-mentioned type of counterbalance mechanisms, and widely
utilized in the garage door industry, are generally cylindrical "collars"
commonly
referred to also as "plugs" (or "cones") which are connected to the so-called
fixed
ends of the torsion springs and are mounted on the aforementioned shaft for
adjusting the deflection of the springs to preset the counterbalance force.
That is,
each torsion spring is usually coaxially mounted onto the overhead shaft and
is
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preferably connected with a stationary plug at one end and a winding plug at
the
other end. Usually, stationary plugs are connected to a fixed structure, such
as for
example, a support bracket rigidly mounted to the wall. Moreover, winding
plugs
are usually removably fixed to the overhead shaft and are used to operatively
connect the torsion spring to the overhead shaft so as to allow a torque
transfer
between the latter two. Hence, the above-mentioned plugs ensure a mechanical
connection between each opposite end of the torsional spring and the support
or a
shaft, depending on whether they are respectively stationary plugs or winding
plugs. The winding plugs usually include one or more setscrews which lock the
plugs to the shaft to prevent rotation therewith except during adjustment of
the
spring deflection. The winding plugs also include sockets for receiving
winding
bars whereby the springs are manually preset, or "preloaded", by rotating the
winding plugs with respect to the shaft using the winding bars and then
locking the
winding plugs to the shaft with the setscrews.
An important problem associated with the aforementioned type of
counterbalancing mechanisms, or with any other type of counterbalancing
mechanism which uses similar plugs (also known as "anchors") and tensioning
springs is that they constitute a serious injury hazard for unexperienced or
inadvertent workers which tamper with said plugs. This arises from the fact
that
when the cable operated doors are closed, the torsion springs, which are under
considerable tension, and the plugs, whether stationary or winding, are
readily
accessible. It has been experienced that several people, either due to
unexperience or inadvertence or any other reason leading to human error, have
unscrewed either one of the plugs, or the support bracket for that matter,
without
taking the necessary precautions, which has resulted in severe personal
injuries
given the considerable tension present in the torsional spring. The above-
described problem is inherent to the plugs known in the art because they are
not
provided with safety means for preventing such adverse consequences.
Therefore, it would be useful to provide a plug which comprises safety means
devised so as to prevent the plug from being readily removed when tension is
present in the torsional spring.
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Another major problem is that none of the types of plugs known in the art
provide a simple, quick, reliable, and cost effective way for operatively
connecting
a torsion spring to an overhead shaft of a counterbalancing mechanism used for
garage doors and the like, while further acting as a safety device for said
counterbalancing mechanism with which they cooperate. Therefore, it would be
useful to provide a simpler, more reliable, easier to use, easier to maintain,
safer,
quicker, and more cost effective plug which is devised for both operatively
connecting a torsion spring to an overhead shaft and for acting also as a
safety
device for the cable-operated door counterbalancing mechanism with which it
cooperates.
Summary of the invention
The object of the present invention is to provide a "plug", also known as a
"collar", an "anchor", or a "cone", which satisfies each of the above-
mentioned
needs.
More particularly, a first object of the present invention is to provide a
plug which comprises safety means devised so as to prevent the plug from being
readily removed when tension is present in the torsional spring.
A second object of the present invention is to provide a simpler, more
reliable, easier to use, easier to maintain, safer, quicker, and more cost
effective
plug which is devised for both operatively connecting a torsion spring to an
overhead shaft and for acting also as a safety device for the cable-operated
door
counterbalancing mechanism with which it cooperates.
In accordance with the present invention, the above objects are achieved
with a plug mounted at one end of a torsional spring operatively connected to
an
overhead shaft of a counterbalancing mechanism, the plug comprising:
CA 02313945 2007-02-13
a cylindrical collar coaxially mounted onto the overhead shaft, said collar
comprising connecting means for connecting the end of the torsional spring
onto
the collar; and
at least one flange projecting longitudinally along the shaft from the collar,
5 said at least one flange being insertable into and cooperable with an
aperture of a
mating part of the counterbalancing mechanism so as to be interlocked with
said
aperture when tension is applied to the torsional spring;
wherein said at least one flange comprises a hook-shaped ridge,
whereby when tension is applied to the torsional spring, the plug rotates
about
the overhead shaft so that said ridge interlocks with a corresponding matching
notch of the aperture.
According to another aspect of the present invention, there is also
provided a plug mounted at one end of a torsional spring operatively connected
to
an overhead shaft of a counterbalancing mechanism, the plug comprising:
a cylindrical collar coaxially mounted onto the overhead shaft, said collar
comprising connecting means for connecting the end of the torsional spring
onto
the collar; and
two flanges projecting longitudinally along the shaft from the collar, each
flange being insertable into and cooperable with a corresponding aperture of a
mating part of the counterbalancing mechanism so as to be interlocked with
said
aperture when tension is applied to the torsion spring;
wherein each flange comprises a hook-shaped ridge, whereby when the
tension is applied to the torsional spring, the plug rotates about the
overhead
shaft so that each corresponding ridge interlocks with a corresponding
matching
notch of each corresponding aperture.
The objects, advantages and other features of the present invention will
become more apparent upon reading of the following non-restrictive description
of a preferred embodiment thereof, given for the purpose of exemplification
only
with reference to the accompanying drawings.
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5a
Brief description of the drawings
Figure 1 is a perspective view of a sectional garage door connected to a
counterbalancing mechanism provided with stationary and winding plugs
according to the prior art.
Figure 2 is a partial perspective view of a sectional garage door
connected to a counterbalancing mechanism provided with a stationary plug and
a winding plug according to preferred embodiments of the invention, said
stationary and winding plugs being shown coaxially mounted about the overhead
shaft and each plug cooperating with a free end of the torsion spring, the
stationary plug being provided with safety means cooperating with a drum
acting
as the mating part of the counterbalancing mechanism.
Figure 3 is a cross-sectional view of a portion of what is shown in figure
2.
Figure 4 is a side elevational plan view of the stationary plug shown in
figure 2.
Figure 5 is another side elevational plan view of the stationary plug
shown in figure 2.
30
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Figure 6 is a detailed view of a portion of the stationary plug shown in
figure 4.
Figure 7 is a top plan view of the drum shown in figure 2, said drum acting
as a mating part according to a preferred embodiment of the invention.
Figure 8 is a rear plan view of what is shown in figure 7.
Figure 9 is a side elevational plan view of what is shown in figure 7.
Figure 10 is a cross-sectional view of the mating part of figure 8 taken
along section AA.
Detailed descriation of a preferred embodiment of the invention
In the following description, the same numerical references refer to similar
elements. The embodiments shown in figures 2-9 are preferred. In the context
of
the present description, the expressions "plug", "collar", "anchor", and any
other
equivalent expression known in the art (such as "cone" for example) used to
designate those structures employed to operatively connect torsion springs
onto
overhead shafts of counterbalancing mechanisms used for garage doors and the
like will be used interchangeably. Although the present invention was
primarily
designed for a counterbalancing mechanism of a garage door, it may be used for
counterbalancing mechanisms of other kinds of doors, such as slidable truck
doors, or with any other items suspended by a cable, as apparent to a person
skilled in the art. For this reason, the expression "garage door" should not
be
taken as to limit the scope of the present invention and includes all other
kinds of
doors or items with which the present invention may be useful. Hence, also in
the
context of the present invention, the expressions "garage door" and "cable
operated door" will be used interchangeably as well.
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The plug 1 according to the preferred embodiment of the invention as it is
illustrated with accompanying drawings is a plug 1 mounted at one end 3 of a
torsional spring 5 operatively connected to an overhead shaft 7 of a
counterbalancing mechanism 9, wherein the plug 1 comprises projecting
interlocking means 11 able to cooperate with corresponding matching means 13
of
a mating part 15 of the counterbalancing mechanism 9, so that when the
interlocking means 11 of the plug 1 are inserted into the corresponding
matching
means 13 and when tension is applied to the torsional spring 5, the
interlocking
means 11 interlock with said matching means 13 of the mating part 15, thereby
preventing the plug 1 from being readily removed therefrom. The plug 1, also
known as a"collar", an "anchor", and a "cone", as aforementioned, is
preferably
devised for use in counterbalancing mechanisms 9 of cable operated doors 17,
such as garage doors 17 and the like. Preferably also, the plug 1 is mounted
at the
end 3 of the torsional spring 5 operatively connected to the overhead shaft 7
of the
counterbalancing mechanism 9 in order to allow a torque transfer between the
torsional spring 5 and the overhead shaft 7 so as to counterbalance the cable
operated door 17, the plug 1 further acting as a safety device because of its
projecting interlocking means 11 which, as mentioned earlier, are devised to
cooperate with corresponding matching means 13 of the mating part 15 of the
counterbalancing mechanism 9, so that when the interlocking means 11 of the
plug 1 are inserted into the corresponding matching means 13 and when tension
is
applied to the torsional spring 5, the interlocking means 11 interlock with
the
matching means 13 of the mating part 15, thereby preventing the plug 1 from
being readily removed therefrom. The projecting interlocking means 11 thus act
as
safety means because they provide an automatic locking mechanism which makes
the plug 1 further operate as a safety device. Hence, the plug 1 according to
the
present invention has a dual purpose, that is, it can act as a conventional
plug 1,
whether it be "stationary" 1 a or "winding" 1 b, as well as a safety device
for the
counterbalancing mechanism 9 with which it cooperates, because of its
projecting
interlocking means 11. The projecting interlocking means 11 may sometimes be
referred to as "ear means" because of the ear-shaped form of their preferred
embodiment shown in the accompanying drawings.
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Referring to figure 1, most cable operated garage doors 17, whether
manually or power operated, are connected to an overhead counterbalancing
mechanism 9 that provides a counterbalancing force in order to decrease the
force
required to open the door 17 and also facilitate its closing. The garage door
17 is
usually connected to the counterbalancing mechanism 9 by means of two cables
19, one at the right and one at the left (not shown). The cables 19 are
usually
made of steel and the lower free end of each cable 19 is usually attached at
the
bottom of the door 17. As illustrated in figure 1, each cable 19 cooperates
with a
corresponding cable drum 21 which is mounted to the overhead shaft 7 in order
to
facilitate raising and lowing of the cable operated door 17. Torque is
transferred
between the torsion spring 5 and the overhead shaft 7 by means of plugs 1
which
operatively connect the shaft 7 to the spring 5 in order to counterbalance the
weight of the garage door 17. Usually, each torsion spring 5 is fixed to the
overhead shaft 7 at one end, by means of a plug 1 known as a "winding plug" 1
b,
and secured to the wall, or a support bracket 23 fixed thereon, at the other
end, by
means of another plug 1 known as a "stationary plug" 1 a. The above-mentioned
types of counterbalancing mechanisms 9 can be found in other types of cable
operated doors 17, such as slidable truck doors for example.
According to the present invention and as better shown in figures 2 to 10,
the plug 1, whether it is a stationary plug 1 a or a winding plug 1 b,
comprises
projecting interlocking means 11 devised to cooperate with corresponding
matching means 13 of a mating part 15 of the counterbalancing mechanism 9, so
that when the interlocking means 11 of the plug 1 are inserted into the
corresponding matching means 13 and when tension is applied to the torsional
spring 5, the interlocking means 11 interlock with said matching means 13 of
the
mating part 15, thereby preventing the plug 1 from being readily removed
therefrom.
According to a preferred embodiment of the invention and as better shown
in figures 2 and 3, each torsion spring 5 is preferably coaxially mounted onto
the
overhead shaft 7 and is preferably connected with a stationary plug 1 a at one
end
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3, and a winding plug 1 b at the other end 3. The stationary plug 1 a of
figures 2 and
3 is shown provided with projecting interlocking means 11 according to the
preferred embodiment of the invention, these projecting interlocking means 11
being shown cooperating with a drum 21 acting as the mating part 15 of the
counterbalancing mechanism 9. It is worth noting that the mating part 15 may
consist of other types of devices, as apparent to a person skilled in the art,
depending on the applications for which plug 1 and mating part 15 are intended
for. For example, as in the case of other counterbalancing mechanisms 9, the
mating part 15 for the stationary plug 1 a may consist of a support bracket 23
securely mounted to a fixed structure, such as a wall. The essence of the
invention
lies in that the plug 1, whether stationary 1 a or winding 1 b, comprises
projecting
interlocking means 11 as described hereinabove, whatever may be their
embodiment, which enable the plug 1 to cooperate as a safety device, in
addition
to fulfilling its conventional function.
As also shown in figures 2 and 3, the winding plug lb is preferably
removably fixed to the overhead shaft 7 and is used to operatively connect the
torsion spring 5 to the overhead shaft 7 so as to allow a torque transfer
between
the latter two. Preferably, the collar of the winding plug 1 b is provided
with sockets
25 for receiving winding bars in order to manually preset a given torque onto
the
torsion spring, prior to securing the winding plug lb onto the overhead shaft
7, by
rotating the winding plug lb with respect to the overhead shaft 7. Once an
appropriate amount of torque ("preload") has been applied to the torsion
spring 5
in order to allow an appropriate counterbalancing force as apparent to a
person
skilled in the art, the winding plug lb is preferably secured to the shaft 7
by means
of setscrews provided for that purpose in order to prevent any substantial
rotational relative movement between the winding plug 1 b and the shaft 7, in
order
to assure a good torque transfer between the torsion spring 5 and the overhead
shaft 7. Preferably, the winding plug 1 b may allow an appropriate relative
sliding of
the corresponding spring end 3 attached thereon so as to compensate for the
contraction or extension of the spring 5 in function of the torsion torque. It
is worth
noting that, although not shown in the accompanying drawings, the winding plug
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1 b, similarly to the stationary plug 1 a and as aforementioned, may also
comprise
projecting interlocking means 11 according to the present invention so as to
act as
a safety device by cooperating with a corresponding mating part 15 when
tension
is still present in the torsional spring 5. For example, as in the case of
other
5 counterbalancing mechanisms 9, the mating part 15 for the winding plug lb
may
consist of a drum 21 securely mounted to the overhead shaft 7.
Because conventional plugs, whether stationary or winding, can be easily
removed from the overhead shaft 7, for maintenance and/or repair of the
10 counterbalancing mechanism 9, by unfastening their setscrews, the
projecting
interlocking means 11 of the present invention enable the plugs 1 to provide
an
automatic locking mechanism, so that when the torsional spring 5 is placed
under
tension, the plug 1 is locked into the mating part 15, preventing tampering
with and
removal of the plug 1, thereby preventing injuries to workers.
As also shown in figures 2 and 3, the plug 1 preferabiy comprises a
cylindrical collar 27 coaxially and slidably mounted onto the overhead shaft
7, the
collar 27 comprising a connection means 29 for connecting the end 3 of the
torsional spring 5 thereon. The projecting interlocking means 11 may consist
of at
least one flange 31 projecting longitudinally along the shaft 7 from the
collar 27,
said at least one flange 31 being able to be inserted into and cooperate with
an
aperture 33 of the mating part 15 so as to be interlocked therewith when
tension is
applied to the torsional spring 5. It is to be understood however, as apparent
to a
person skilled in the art, that the projecting interlocking means 11 may take
on
various other embodiments without departing from the scope of the invention.
Furthermore, it is worth noting that the manner in which the plug 1 is mounted
onto
the overhead shaft 7 and the way of connecting the plug 1 to the torsional
spring 5
may also take on various other embodiments.
As aforementioned and as better shown in figures 4 to 6, the present
invention is characterized in that the plug 1 comprises projecting
interlocking
means 11 able to cooperate with corresponding matching means 13 of the mating
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part 15 of the counterbalancing mechanism 9, so that when the interlocking
means
11 of the plug 1 are inserted into the corresponding matching means 13 and
when
tension is applied to the torsional spring 5, the interlocking means 11
interlock with
the matching means 13 of the mating part 15, thereby preventing the plug 1
from
being readily removed therefrom. Thus, the projecting interlocking means 11
effectively operate as safety means, making the plug 1 act as a safety device
in
addition to allowing it, whether stationary 1 a or winding 1 b, to fulfill its
conventional
role. As better shown in figures 4 and 5, the projecting interlocking means 11
preferably consist of two flanges 31 projecting longitudinally along the shaft
7 from
the collar 27, each flange 31 being able to be inserted into and cooperate
with the
corresponding aperture 33 of the mating part 15 so as to be interlocked
therewith
when tension is applied to the torsional spring 5. It is worth noting that the
plug 1
may comprise more than two flanges 31, preferably symmetrically disposed
thereon, depending on the application for which it is intended, as apparent to
a
person skilled in the art. As better shown in figure 6, each flange 31
comprises a
hook-shaped ridge 35, whereby when tension is applied to the torsional spring
5,
the plug 1 rotates about the overhead shaft 7 so that each corresponding ridge
35
interlocks with a corresponding matching notch 37 of the corresponding
aperture
33, the matching notches 37 of the corresponding apertures 33 being better
shown
in figures 7, 8, and 10. Preferably, once the projecting interlocking means 11
of the
plug 1 are interlocked with the matching means 13, they cannot be removed from
the mating part 15 without removing tension in the torsional spring 5. This
feature
enables the risk of inadvertently dismantling the plug 1 from the
counterbalancing
mechanism 9 to be considerably reduced, if not completely eliminated, and
consequently the risk of personal injury is also reduced. Preferably also,
each
flange 31 further comprises a groove 39 cooperating with a corresponding
projecting clip 41 of the mating part 15 so as to secure positioning of the
plug 1
inside the mating part 15 upon insertion of each flange 31 into the
corresponding
aperture 33, as better shown in figure 3. As shown in figure 9, the mating
part 15
preferably has fastening means 43 for mounting the mating part 15 onto an
appropriate location, such as the overhead shaft 7 or the support bracket 23
for
example, depending on the function of the mating part 15 and of the plug 1.
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Preferably and as better shown in figure 3, a portion of the torsional spring
5
comprising the end 3 thereof is coaxially mounted onto the cylindrical collar
27.
Furthermore, the connecting means 29 preferably consist of, that is, the
collar 27
preferably further comprises external threading for facilitating insertion and
positioning of the plug 1 into the above-mentioned portion of the torsional
spring 5,
the external threading being better shown in figures 4 and 5.
The present invention is an improvement and presents several
advantages over other plugs 1 known in the prior art, such as the one
illustrated in
figure 1. For instance and as shown hereinabove, in addition to enabling the
plug
1, whether stationary 1a or winding 1b, to fulfill its conventional function,
the
projecting interlocking means 11 of the plug 1 according to the present
invention
act as safety means, thus providing an automatic locking mechanism preventing
the plug 1 from being readily removed from the mating part 15 when tension is
still
present in the torsional spring 5, thus preventing serious injuries to
inexperienced
or inadvertent workers tampering with the plugs 1. Hence, the invention has a
dual
function, that of acting as a conventional plug, whether stationary 1a or
winding
1 b, and as a safety device. Furthermore, the present invention may be used in
the
garage door industry, with counterbalancing mechanisms 9 of new garage doors
17 or existing garage doors 17. As it is evident from reading the above
description,
the present invention is a simpler, more reliable, easier to use, easier to
maintain,
safer, quicker and more cost effective plug 1 which is devised for both
operatively
connecting a torsion spring 5 to an overhead shaft 7 and for acting as a
safety
device for the cable-operated door counterbalancing mechanism 9 with which it
cooperates. Moreover, the present invention may be used with other kinds of
doors 17, such as slidable truck doors 17, or with any other items suspended
by a
cable, as apparent to a person skilled in the art.
Of course, numerous modifications could be made to the above-described
embodiments without departing the scope of the invention as defined in the
appended claims.
