Note: Descriptions are shown in the official language in which they were submitted.
CA 02369705 2002-O1-30
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PLUG WITH ABUTMENT FLANGE FOR ABUTTING SPRING TAIL
OF CORRESPONDING TORSION SPRING
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.
Background 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. !n 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
door
opening and closing mechanism. In other words, lighter weight, lower 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 a
failure of
the door opening and closing mechanism, which can result in serious injury or
damage.
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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 a 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 a
fixed
structure such as the wall for example 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. The torsion
springs
are adjusted to properly balance the weight of the door so that minimal
opening
and closing efforts are required, either manually ~r when motor controlled. An
example of a conventional cable-operated door and its corresponding
counterbalancing mechanism is shown in Figure 1.
It is also known in the art that conventional, low cost adjustment devices
used for the above-mentioned type of counterbalance mechanism, and widely
utilized in the garage door industry, are generally cylindrical "collars"
commonly
referred to also as "plugs" (also known as "cones", "anchors", etc.) which are
connected to the so-called fixed ends of the torsion springs and are thus
mounted
on the aforementioned shaft for adjusting the deflection of the springs to
preset the
counterbalance force. Usually, each torsion spring is operatively secured to
the
wall at one end, by means of a plug known as a "stationary plug", and is fixed
to
the overhead shaft at the other end, by means of a plug known as a "winding
plug". These winding plugs usually include one or more setscrews which lock
the
collars to the shaft to prevent rotation thereabout except during normal
adjustment
of the spring deflection. The winding plugs also usually include sockets for
receiving winding bars whereby the springs are manually preset, or
"preloaded",
by rotating the collars with respect to the shaft using the winding bars and
then
locking the plugs to the shaft with the setscrews. Each plug, whether
stationary or
winding, may also include a slot onto which a corresponding free end of the
torsion
spring is hooked on. These slots are usually T-shaped, and are thus commonly
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known as "T-slots". An example of prior art winding and stationary T-slot
plugs are
shown in Figures 2 and 3 respectively.
Presently, the T-shape of the slots of the plugs known in the art allows the
introduction of the spring's tail without the use of any tool. Once the spring
tail is
introduced into the T-slot of the collar, both the collar and the spring are
then
introduced onto a shaft and installed on site, after which the collar is
pushed
towards the spring and then rotated around the spring axis in order to have
the
spring tail blocked against a corresponding hooking groove of the T-slot of
the plug
due to the potential energy present in the torsion spring. The combined effect
of
these components holds the assembly together without any other accessories.
An important problem associated with the aforementioned type of plug is
that once the spring tail of the torsion spring is inserted into the T-slot of
the plug
for hooking thereon, a user may inadvertently load the torsion spring in the
wrong
way, i.e. may wind the plug about the overhead shaft in a direction contrary
to the
natural winding direction of the type of torsion spring being used. This
mishap is
commonly referred to as "miswinding" or "back winding". For example, when
referring to Figure 4, there is shown a perspective view of an unloaded spring
wound in an anti-clockwise direction. The spring would be "miswound" or "back
wound" if a load would be preset onto the spring by winding a plug connected
thereto in a clockwise manner, i.e. against the natural winding direction of
the
spring.
An adverse consequence of back winding a torsion spring onto an
overhead shaft results in the spring tail not hooking on properly onto its
corresponding hooking groove of the T-slot of the plug and often causes, after
just
a few operating cycles, the spring tail to "jump" out of said T-slot, thereby
rendering the counterbalancing mechanism inoperable or causing several
damages to the components thereof, which may in turn cause personal injuries
to
people in the vicinity of the counterbalancing mechanism, whether installers
or the
users of the garage door containing such counterbalancing mechanisms.
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Hence, in light of the aforementioned, there is a need for an improved plug
which, by virtue of its design, would be able to prevent a user from
inadvertently
miswinding a torsion spring thereon. There is also a need for an improved plug
which, by virtue of its components, would be able to minimize the above-
mentioned adverse effects in the advent of a torsion spring having been
miswound.
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 some of the above-
mentioned
needs and which is thus an improvement overthe plugs known in the prior art.
In accordance with the present invention, the above object is achieved, as
will be easily understood, with a plug such as the one briefly described
herein and
such as the ones exemplified in the accompanying drawings.
Preferably, the plug according to the present invention can either be a
stationary plug or a winding plug.
The objects, advantages and other features of the present invention will
become more apparent upon reading of the following non-restrictive description
of
preferred embodiments thereof, given for the purpose of exemplification only
with
reference to the accompanying drawings.
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.
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Figure 2 is a plan view of one of the winding plugs shown in Figure 1.
Figure 3 is a plan view of one of the stationary plugs shown in Figure 1.
5 Figure 4 is a perspective view of a torsion spring according to the prior
art.
Figure 5 is a perspective view of the torsion spring of Figure 4 cooperating
with a stationary plug according to a preferred embodiment of the invention.
Figure 6 is a perspective view of the stationary plug shown in Figure 5.
Figure 7 is a perspective view of the torsion spring of Figure 4 cooperating
with a winding plug according to a preferred embodiment of the invention.
Figure 8 is a perspective view of the winding plug shown in Figure 7.
Figure 9 is a perspective view of a winding plug according to another
preferred embodiment of the invention.
Figure 10 is another perspective view of the winding plug shown in Figure
9.
Figure 11 is a perspective view of a winding plug according to yet another
preferred embodiment of the invention.
Figure 12 is another perspective view of the winding plug shown in Figure
11.
Figure 13 is a cross-sectional view taken along line A-A of the assembly
shown in Figure 7, the torsion spring being shown in a wound configuration.
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Figure 14 is a cross-sectional view taken along line A-A of the assembly
shown in Figure 7, the torsion spring being shown in a back wound
configuration.
Detailed description of a preferred embodiment of the invention
In the following description, the same numerical references refer to similar
elements. The embodiments shown in Figures 5-15 are preferred.
Moreover, although the present invention was primarily designed for use
with 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.
Moreover, in the context of the present invention, 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. Furthermore,
expressions such as "spring tail" and "free end", as well as any other
equivalent
expressions and/or compound words thereof, may also be used interchangeably in
the context of the present description. The same applies for any other
mutually
equivalent expressions, such as "miswinding" and "back winding" for example,
as
also apparent to a person skilled in the art.
In addition, although the preferred embodiment of the present invention as
illustrated in the accompanying drawings comprises components such as flat
outer
surfaces, setscrews, sockets, etc., and although the preferred embodiment of
the
T-slot and corresponding abutment flange of the present invention as shown
consists of certain geometrical configurations as explained and illustrated
herein,
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not all of these components and geometries are essential to the invention and
thus
should not be taken in their restrictive sense; i.e. should not be taken as to
limit the
scope of the present invention. It is to be understood, as also apparent to a
person
skilled in the art, that other suitable components and cooperations
thereinbetween,
as well as other suitable geometrical configurations may be used for the T-
slot and
corresponding abutment flange of the plug according to the present invention,
as
will be explained hereinafter, without departing from the scope of the
invention.
The plug 1 according to the preferred embodiment of the invention as it is
illustrated with accompanying drawings is a plug 1 for use in counterbalancing
mechanisms 3 of garage, doors 5 and the like. The plug 1, also known as a
"collar", an "anchor", and/or a "cone", as aforementioned, is preferably used
to
operatively connect an overhead shaft 7 to a torsion spring 9
coaxiallylconcentrically mounted onto the overhead shaft 7.
Referring to Figure 1, most cable-operated doors 5, whether manually or
power-operated, are connected to an overhead counterbalancing mechanism 3
that provides a counterbalancing force in order to decrease the force required
to
open the door 5 and also facilitate its closing. The garage door 5 is usually
connected to the counterbalancing mechanism 3 by means of twa cables, one at
the right and one at the left. The cables are usually made of steel and the
lower
free end of each cable is usually attached at the bottom of the door 5. As
illustrated in Figure 1, each cable cooperates with a corresponding cable drum
13
which is mounted to the overhead shaft 7 in order to facilitate raising and
lowering
of the cable-operated door 5. Torque is transferred between the torsion spring
9
and the overhead shaft 7 by means of plugs which operatively connect the shaft
7
to the spring 9 in order to counterbalance the weight of the garage door 5.
Usually,
each torsion spring 9 is fixed to the overhead shaft '7 at one end, by means
of a
plug known as a "winding plug", and operatively secured to the wall at the
other
end, by means of another plug known as a "stationary plug". The above-
mentioned types of counterbalancing mechanisms can be found in other types of
cable-operated doors 5, such as slidable truck doors for example.
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Referring now to Figures 2 and 3, there is shown examples of typical T-
slot plugs, also known as "cones", as already known in the prior art. Figure 2
illustrate a winding plug and Figure 3 illustrates a stationary plug. The form
of their
slots allows the introduction of the free end of the spring 9, also known as a
"spring tail", without the use of any tool. Once the spring tail is introduced
into the
T-slot of the collar, both the collar and the spring 9 are then introduced
onto the
shaft 7 and installed on site, after which the collar is pushed towards the
spring 9
and then rotated around the spring axis in order to have the spring tail
blocked
against a corresponding hooking groove of the T-slot of the plug due to the
potential energy present in the torsion spring 9. This type of plug is
suitable for
most torsion springs 9 but causes several problems, in that, among other
things, if
the torsion spring 9 is miswound, i.e. if the torsion spring 9 is loaded by
winding
the plug in a direction contrary to the natural winding direction of the type
of torsion
spring 9 being used, then very often this will result in the spring tail not
hooking
properly onto its corresponding hooking groove of the T-slot of the plug and
will
often cause the spring tail to "jump" out of said T-slot through the opposite
hooking
groove, thereby rendering the counterbalancing mechanism 3 inoperable or
causing several damages to the components thereof.
According to the present invention and as better shown in Figures 5-15,
the plug 1, whether it is a stationary plug 1a or a winding plug 1b, comprises
a
cylindrical collar 15 and a cylindrical flange 17. The cylindrical collar 15
has
opposite first and second portions 19, 21. The collar 15 is provided with a
hooking
slot 23 for hooking a free end 25 of the torsion spring 9 therein and the
torsion
spring 9 has a segment coaxially mounted about the first portion 19 of the
collar
15. The cylindrical flange 17 is rigidly affixed to the second portion 21 of
the collar
15. The flange 17 is used for transferring a torque between the torsion spring
9
and the overhead shaft 7 when the flange 17 is securely fixed about the
overhead
shaft 7. The plug 1 according to the present invention is characterized in
that it
further comprises an abutment flange 27. Among many other purposes, the
abutment flange 27 is mainly devised to abut with the spring tail 25 of the
torsion
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spring 9 in the advent of the torsion spring 9 being "miswound" (also known as
"back wound"), so as to prevent the spring tail 25 from "jumping" out of the
hooking slot 23, as better shown in Figure 14. Indeed, the abutment flange 27
is
devised to force the spring tail 25 to remain in the hooking slot 23 even if
the
torsion spring 9 is wound in the wrong way. Preferably, as better shown in
Figures
5-12, the abutment flange 27 comprises curved recesses 29 for "retaining"
therein
the spring tail 25 of the torsion spring 9 should the latter be miswound.
Furthermore, the abutment flange 27 preferably further comprises a projection
31,
as better shown in Figures 5-8 and 13-14, for preventing the spring tail 25 to
be
inadvertently hooked onto the abutment flange 27 instead of its corresponding
hooking groove 33. The shape and the size of the abutment flange 27 and of its
components, particularly its height, as well as the nature (material being
used) of
the plug 1 and of the corresponding abutment flange 27 being used therewith,
should be selected accordingly, depending on the particular applications for
which
the plug 7 and abutment flange 27 are intended for and depending on the
particular type of torsion spring 9 with which they are used, as apparent to a
person skilled in the art.
Furthermore, as better shown in Figures 5-12, the abutment flange 27 is
preferably shaped and sized for intuitively guiding an installer of the
counterbalancing mechanism 3 on how to properly wind the torsion spring 9
depending on the type of spring 9 being used, i.e. the abutment flange 27
serves
as a dividing line between the two corresponding hooking grooves 33 of the
hooking slot 23, so that once the spring tail 25 is inserted into the plug 1
and
oriented towards a corresponding hooking groove 33 by virtue of the curvature
of
the spring tail 25, then one simply has to wind the winding plug about the
shaft 7
towards the inoccupied corresponding hooking groove 33 of the slat 23, as
better
shown in Figures 5, 7, 13 and 14, and as can be easily understood.
Nence, a substantial technical innovation of the present invention resides
in the fact that the plug 1 comprises an abutment flange 27 which limits the
possibility of misuse (i.e. miswinding) and reduces the risk of injury which
may
CA 02369705 2002-O1-30
result therefrom upon installation. Indeed, from a practical point of view,
when an
anchoring plug is wound in a wrong way, also known as "back winding" as
aforementioned, then the spring 9 and tail 25 will tend to go out of the plug
1,
which may be very dangerous considering the potential energy contained in the
5 torsion spring 9. As explained hereinabove, the addition of an abutment
flange 27
to the plug 1 reduces this possibility of misuse in two distinct manners.
Firstly,
because of the presence of the abutment flange 2T, it is more clear as to
which
way the torsion spring 9 must be wound even for a user which is not familiar
with
installing counterbalancing mechanisms. Secondly, should the torsion spring 9
be
10 back wounded, then the abutment flange 27 will keep the spring tail 25 in
the
hooking slot 23, in such a way that the spring tail 25 will not jump out
therefrom
which thus reduces the possibility of personal injuries, or even damages to
the
counterbalancing mechanism.
According to other preferred embodiments of the invention, as better
shown in Figures 9-12, the plug, whether stationary or winding, may be defined
left
or right handed, which means that the plug 1 may only be used with a
corresponding left or right torsion spring 9. The expressions "left" and
"right" are
used in the context of the present description similarly to the expressions
"clockwise" and "anti-clockwise" to express different types of winding
directions for
the torsion springs 9, as apparent to a person skilled in the art. Hence, for
a given
torsion spring 9, the universal plug 1 with symmetrical abutment flange 27
such as
the ones shown in Figures 5-8 and 13-14 maybe used, or a corresponding right
or
left plug 1 with asymmetrical abutment flange 27, such as the ones shown in
Figures 9-12, may also be used, according to the present invention.
Preferably, the plug 1 and its abutment flange 27, as well as the other
components thereof, are made integral to each other, that is, they are all
preferably made of one single material. Furthermore, the plug 1 is preferably
made
of an appropriate material; such as a metal, polymer, etc., and by means of a
corresponding suitable manufacturing process, such as die casting, injection
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molding, etc., as it is well known in the art, depending on the applications
for which
the plug 1 is intended for, as apparent to a person skilled in the art.
As may now be appreciated, the present invention is an improvement and
presents several advantages over other plugs known in the prior art, such as
the
one illustrated in Figures 2 and 3. Indeed, as described herein, the plug 1
and its
abutment flange 27 according to the present invention enables to prevent a
user
from inadvertently miswinding a torsion spring 9 thereon. The plug 1 according
to
the present invention is also advantageous in that it enables, as explained
hereinabove, to minimize adverse effects resulting from a torsion spring 9
having
been miswound (or "back wound"). The present invention is also advantageous in
that it allows the free ends 25 of the torsion springs 9 (a(so known as
"spring tails")
to be hooked onto the slots 23 of the plugs 1; easily, quickly, safely, and
reliably,
without any special tooling, while guiding a user to properly wind the torsion
spring
9 along the correct winding direction. Conversely, the present invention also
allows
the same spring tails 25 to be hooked off the slots 23 of the plugs 1, with
the same
above-described advantages, for an easier maintenance andlor repair to the
counterbalancing mechanism 3. The present invention may be used in the garage
door industry, with counterbalancing mechanisms 3 of new garage doors 5 or
existing garage doors 5. As it is evident from reading the above description,
the
present invention is a more reliable, easier to use, easier to maintain,
safer,
quicker and more cost effective plug 1 than those available in the prior art.
Furthermore, the present invention may be used with other kinds of doors 5,
such
as slidable truck doors, 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 from the scope of the invention as defined in
the
appended claims.
