Note: Descriptions are shown in the official language in which they were submitted.
CA 02385131 2002-05-07
41722-0002
Vent Closure Flap and Method of Assembly
FIELD OF THE INVENTION
This invention relates generally to the art of vent closures and methods for
assembling same.
BACKGROUND OF THE INVENTION
Vent ducts which lead exhaust, such as lint and moisture from clothes dryers
or
moisture from a bathroom, to the exterior of a building, terminate with a cap
or
closure assembly which restricts outside air from entering the vent duct.
Generally
the duct exits are fitted with either a hinged rigid closure plate or a rubber
sheet like
flap. These have an open exhaust discharge position and a closed position
which
relies on gravity for closure. Some hinged closures include costly coil
torsion springs
to assist flap closure. Other hinged closures are constructed from spring
steel,
thus requiring separate front and rear faces, and a hinge gap, as discussed in
more
detail below.
In the winter hinged plates may be prone to freezing due to moisture from
exhaust
air and low ambient temperatures. As the hinge ages, it may deteriorate due to
oxidization. Hinges are also prone to sticking in open or closed positions due
to
particulate build up from exhaust air, thus allowing outside air into the duct
and into
the building.
With the use of prior art hinged plates, even a small amount of unwanted
matter
such as lint can cause problems of vent blockage and/or vent-plate sticking in
an
open position letting cold air come into the vent line and the building's
interior.
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Flaps which are made from rubber like materials alone are typically single
layer and
are prone to tearing at their fixed point due to constantly fluctuating open
and closed
motion. These flaps tend to flutter like a flag in the wind, transmitting
noise into the
building. This type of flap also requires a baffle to create a maximum open
position
which restricts air flow.
Both types of closures thus create noise when closing which can echo back into
the
building. Also, due to their dependence on gravity and the change in
performance
due to weathering, both types of vent closures are unreliable and prone to
failure.
Failure of these flaps in the open position cause buildings to lose heat, thus
reducing
thermal efficiency and creating an inlet for noise. Failure of these flaps in
a closed
position causes moisture buildup. Thus, for example, a blocked duct exhausting
from the clothes dryer may allow moisture to trickle back into the dryer or at
least
prevent the clothes dryer from achieving optimum drying operation. Any of this
can
cause the homeowner to assume, wrongly, that the dryer's motor and/or heater
components needs replacement, and extra service calls are wasted because of
the
wrong diagnosis as to the cause of clothes not being satisfactorily dried.
Even without the waste and expense of service calls, the homeowner wastefully
attempts to correct the problem by repetitive dryer cycles, with a consequent
great
waste and cost of electricity and/or gas. The temptation for a serviceman to
replace
motor and/or heater components has no doubt led to needless replacement of
parts,
and needless service, all of course at the homeowner's expense.
Also, lint buildup can be so extensive in the form of an upstream backup into
the
interior ductwork, as to cause a fire hazard when the buildup reaches close to
the
dryer's heater element.
When bathroom, kitchen, or other building exhaust duct plates experience hinge
failure, the plate may remain stuck in a closed position, preventing proper
exhaust
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function, or may remain stuck in an open position, thus allowing outside air
to travel
into the building, which impairs heating, cooling and insulation efforts.
U.S. patent no. 3,292,658 to Scaramucci teaches a check valve with a hinge
structure. A reinforcing member made of a flexible material such as nylon or
metallic spring serves to increase the tensile strength of the hinge spring
means..
The hinge spring means is of a relatively complex circular structure, which
increases
the cost and chance of failure of the spring, and creates a region receptive
to lint or
other materials, Which may block the function of the spring.
U.S. patent no. 4,304,265 to Sell teaches a spring-biased flap valve for
chemical
pumps. Sheet metal like portions provide a spring return of the flap valve.
The
design taught by Sell is relatively complex, expensive, and provides a hinge
gap
which is_receptive_to blockage. The sheet metal portions, extend in length and
width
along the entire body, and thus add to the expense and weight of the unit. The
use
of Teflon for the external faces of Sell renders the flap valve noisy, and
thus
unsuitable for domestic use.
U.S. patent no. 4,449,549 to Weck teaches a shutter device for air conduits. A
rubber elastic lamellae is partly coded on its external surface with plates
for
reinforcement. Like Scaramucci and Sell, the design of Weck.provides a gap
receptive to blockage and impairment of the hinge. Weck does not teach any
spring.
. U.S. -patent no. 4,823,836 to Bachmann et al. teaches dampers comprised of
three
leaf springs for sealing. As with the reinforcing members of Sell and
Scaramucci,
the leaf springs of. Bachmann et al. extend the entire length and Width of the
closure.
Bachmann et al. does not provide any closure body apart from the leaf springs.
The
noise that one would expect with the damper Bachmann et al. renders his design
30- unsuitable for domestic use.
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U.S. patent no. 5,355,910 to Gies et al. teaches a two layered flap. Gies et
al. does
not teach any spring. Gies et al. provides a hinge gap, which is vulnerable to
blockage and thus impairment of function.
U.S. patent no. 5,194,038 to Klomhaus et al. similarly teaches a one way air
valve,
without a spring. Also like Gies et al., Klomhaus et al. teaches a spring
design
having a gap which is vulnerable to blockage and thus impairment of function.
SUMMARY OF THE INVENTION
In accordance with the present invention, a vent flap and method is provided
which
addresses the problems inherent in conventional vent flap assemblies. In
accordance with an exemplary embodiment of the present invention, a vent
closure
flap comprises a body configured for attachment to a proximal side of a vent
outlet,
the body extending lengthwise from the proximal side to a distal side, wherein
a
spring strip is configured to assist the body in resuming the closed position.
The
body is configured to assume a closed position in an absence of exhaust
pressure,
assume an open or partially open position during exhaust pressure, and resume
the
closed position upon removal of exhaust pressure.
The spring strip may have a bend to assist the body in resuming the closed
position.
The spring may be constructed from a material selected from the group
consisting of
tempered steel, stainless steel, carbon steel, metal alloys and polymer
material. In
an embodiment, the spring extends from the proximal side to a distal side of
the vent
closure flap.
In another embodiment, the invention further provides a stiffening strip. The
stiffening strip may be perpendicular to the body. A stiffening strip may be
located at
the distal side of the body. A stiffening strip may be located at the proximal
end of
the body.
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The body may be constructed from a material selected from the group consisting
of
neoprene, EPDM, SBR, cross-linked polyethelyne, microcellular urethane, solid
rubber, open cell polyurethane foam, copolyester, acetate, and polycarbonate
sheet.
The stiffening strip may be constructed from a material selected from the
group
consisting of tempered steel, stainless steel, carbon steel, metal alloys and
polymer
material. The body may be flexible.
The invention also provides methods for assembling vent closure flaps of the
present invention, comprising configuring a flexible body to be sized to cover
a vent
outlet.
A method may comprise: (a) configuring a flexible body to twice a size
required to
cover a vent outlet; (b) applying an adhesive to an inner face of the body;
and (c)
folding the body along a center line to form a body configured to a size
required to
cover a vent outlet.
In a further embodiment, the method for assembling a vent closure flap further
comprises affixing a spring strip lengthwise along the body. The method may
further
comprise bending the spring strip to assist the body in resuming a closed
position.
The method may further comprise affixing a stiffening strip perpendicular on
the
body. A stiffening strip may be affixed at a distal side of the body. A
stiffening strip
may be affixed at a proximal end of the body.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in relation to the accompanying drawings
in
which:
Figure 1 is side view of a vent box and closure plate of the prior art;
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Figure 2 is an exploded view of a closure flap of the present invention;
Figure 3 is a partial breakaway view of a closure flap of Figure 1.
DESCRIPTION OF A PREFERRED EMBODIMENT
The invention provides a novel and advantageous flexible vent duct flap.
As shown in prior art Figure 1, the vent duct 34 is typically one which leads
exhaust
substance from associated equipment such as a clothes dryer interior of a
building
wall 36, for venting discharge to the exterior of the wall 36.
Conventionally, the vent duct outlet 32 is connected to and extends outwardly
of the
wall 36, and the outlet 32 has a movable closure plate 38, the plate 38 being
movably supported by hinge 39 between a substance-discharge position 40, which
permits the exhaust substance to be discharged through the vent duct outlet
32, and
a closed (vertical) position (not shown) against the outlet 32's mounting
panel 41,
providing a loosely held closure of the vent duct outlet 32.
A protective termination box 30 is shown, comprising an enclosure formed by
panel
means having one or more openings sized to block entry from the wall 36;
exterior,
inwardly toward the associated clothes dryer equipment, of matter of any size
significantly larger than the particles of exhaust substance (typically small
lint
fragments and moisture condensate) for which the box 30 is provided.
Other hinged vent plates of the prior art are known. For example, where the
duct
exhaust opening is essentially circular in cross-section, a circular vent
plate with a
hinge running through its center line and moveably attaching the plate to the
duct
exhaust opening is know.
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The vent flap of the present invention protects a vent duct of a type which
leads
exhaust substance such as lint and moisture being conveyed from a clothes
dryer,
kitchen, bathroom or building generally, for venting discharge to the exterior
of a
building's wall, the vent duct outlet having a movable closure flap which can
flexibly
move from a substance-discharge position and a closed position.
The present invention as shown in exploded Figure 2 and partial breakaway
Figure
3. Closure flap 10 comprises a folded body for which can be made of neoprene
or
any rubber like substance. Inserted within the folded body is an upper
stiffening
strip 12 and a lower stiffening strip 13, which facilitate a seal on the duct
when the
flap is closed. Also enclosed in the folded main body is spring strip 14.
Spring strip
14 is located medially and lengthwise in relation to body 20. "Strip" is used
herein to
refer to a long narrow piece, by which is meant the strip is substantially the
length of
the body and is significantly narrower in width than the body. Spring strip 14
has a
bend 16 which facilitates complete closure of the flap.
The top 18 of the flap is fixed above the duct opening to the exterior by any
conventional means (not shown) such as a metal strip screwed, spot welded, or
otherwise fixed over top 18.
The main body 20 may be constructed from any materials which meet the
application requirements for restriction of flow (exhaust air or granular
solids). The
body material may be neoprene for non-corrosive air exhaust. Other materials,
including EPDM, SBR, cross-linked polyethelyne, microcellular urethane, solid
rubber, open cell polyurethane foam, copolyester, acetate, or polycarbonate
sheet
(for high impact application, granular solids) may be used. Construction
materials
are not limited to the listed materials.
In production, the main body 20 may be cut to twice the desired finished
length.
Adhesive is applied, generally by spray, to inner face 22. Brush or roller
applied
adhesives or tapes (including double sided tape), or other fasteners known in
the art
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may be used. Adhesive is selected per application for suitability with
construction
materials and resistance to low/ high temperature variance.
After adhesive is applied to the inner face 22, the components are positioned,
and
the main body 20 is completed by folding along its half along fold line 24 and
compressed with a light weight roller. The adhesive covered inner face 22 can
bond
instantly and the finished assembly may be immediately put into service.
The pre-stressed spring strip 14 may be constructed from tempered
steel,'stainless
steel, carbon steel, metal alloys or polymer material. Stiffening strips 12,
13, may be
constructed from any rigid material, usually but not limited to, light gauge
sheet
metal. Two pieces, upper strip 12 and lower strip 13, are sufficient for most
applications, but more may be added if required. These strips 12, 13, are
added to
maintain the shape of the body 20.
In some cases, the main body material alone may provide sufficient flexibility
and
memory resilience that the pre-stressed spring strip 14 and/ or stiffening
springs 12,
13 need not be installed.
The use of a spring strip in place of a hinge renders the product free of the
risks
associated with hinge freeze up or obstruction, discussed above. The use of a
softer, flexible rubber like main body in place of a hard plastic body
provides for a
gentler opening and closing action, lower noise and improved durability. The
configuration of the spring strip and the stiffening strips provides for a
excellent seal
when there is no exhaust pressure. The invention provides all the benefits
associated with spring steel hinges while minimizing the quantity of spring
steel
required to be used, thus minimizing cost and product weight.
The present invention also has the benefit of being simple in design and
construction. The present invention provides further benefits over the prior
art,
which should be considered, both as to their individual benefit, and to what
may be
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'considered to be also their synergistic benefit toward the invention as a
whole. Such
features include:
(a) Easy to use and to install;
(b) Certainty as to operation and protective effects;
(c) Economical assembly and installation;
(d) No adverse effect on exhaust duct or flap-closure operability;
(e) Virtually problem free once installed;
(f) Long lasting, with minimal or no maintenance;
(g) Factory installed or sold separately as a replacement piece;
(h) Does not rely on gravity for closure - may be installed in any
orientation;
(i) Rubber-like body retains temperature, thus there is less condensation, and
less
risk of freeze-up;
(j) Spring assistance provides constant back pressure;
(k) Movement of flap is proportional to exhaust pressure - no cyclic loading/
unloading of pressure and thus no cyclic loading/ unloading of fan motor,
resulting in
greater efficiency;
(I) The spring strip is enclosed in a water tight and air tight assembly, and
not subject
to corrosion;
(m) Withstands weathering;
(n) Quiet in operation; and
(o) Provides spring action with minimal use of spring steel materials.
Thus, it will be appreciated that as a result of the present invention, a
highly effective
improved vent closure flap and method, are provided by which the principle
objective, among others, is completely fulfilled. It is contemplated and will
be
apparent to those skilled in the art from the preceding description and
accompanying
drawings, that modifications and/or changes may be made in the illustrated
embodiments without departure from the present invention. Accordingly, it is
expressly intended that the foregoing description and accompanying drawings
are
illustrative of preferred embodiments only, not limiting, and that the true
spirit and
scope of the present invention be determined by reference to the appended
claims.
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