Note: Descriptions are shown in the official language in which they were submitted.
BP13942-088 2129375
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Title: EXHAUST VENT COVER
FIELD OF THE INVENTION
This invention relates to a cover, and in
particular to a cover of the type used for covering
bathroom or kitchen exhaust pipes which extend through
roofs and the like.
BACKGROUND OF THE INVENTION
In residential construction, there is often the
need to provide an exhaust vent from a room, particularly
a kitchen or a bathroom, directly to the outside. Such
exhaust vents typically comprise vertical pipes or
conduits which have at their lower end a fan. Upon
activation the fan causes air to be exhausted from the
room through the conduit to the outside.
In the past, it has been common to provide a
vent cover which includes a one-way valve at the exit end
of the conduit. Upon the vent being activated, the
pressure increases in the conduit and the one-way valve
opens to allow the air to exit from the conduit.
Typically, such vent covers are formed from metal and the
opening and closing of the vent cover is associated with
a tinny clanking noise. Under the influence of wind or
the like, the valve may be caused to open causing a
clanking noise which is carried down the pipe, and through
the vent into the living space. For bathrooms associated
with bedrooms, this clanking noise can be a source of
irritation to anyone trying to sleep. In extreme
climates, unwanted opening of the valve can also allow
cold or hot air to enter the conduit and can affect the
comfortable temperature inside the building.
Additionally, the prior designs are susceptible to rain or
the like leaking in through the exhaust cover and down the
conduit.
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SDMMARY OF THE INVENTION
What is desired therefore is an exhaust vent
cover which is capable of preventing snow or rain from
entering into the conduit and which remains in a closed
position when not in use. Such a design would prevent
cold or hot air from penetrating the conduit and would
also be quiet in that there would be no clanking sound
transmitted down the conduit when the valve opens or
closes.
Therefore, going to the present invention there
is provided:
An exhaust vent cover comprising:
a peripheral flange for attaching the cover to
a surface;
a hollow body extending upwardly from the flange
and having an air passageway communicating with an open
front, said body including an overhang extending beyond
said open front; and
a replaceable grill covering said open front,
said grill including a plurality of water inhibiting fins,
which inhibit water from entering the open front.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments of the invention will now
be described with reference to the attached drawings,
which by way of example only, illustrate certain preferred
configurations:
Figure.1 is a perspective view from above and to
one front of one embodiment of the present invention;
Figure 2 is an enlarged view of a portion of
Figure 1;
Figure 3 is a side view of the invention of
Figure 1;
Figure 4 is a perspective view from above and to
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the front of a second embodiment of the present invention;
and,
Figure 5 is a side view of the invention of
Figure 4.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
According to the present invention there is
provided an exhaust vent cover shown as 10 in Figures 1
and 3. This exhaust vent cover 10 is preferably formed
from plastic. Preferably, the exhaust vent cover 10 is
injection molded from talc filled polypropylene having a
thickness of between 75 to 90 thousanths of an inch as an
average. It will be appreciated that other plastics and
thicknesses may also be used, provided that such other
plastics have suitable colour fastness, strength and
wearability for outdoor use.
The exhaust vent cover 10 includes a peripheral
flange 12 surrounding the base of a hollow body 14. The
peripheral flange 12 includes means for attaching the
cover 10 to a surface, such as a roof or wall. One form of
acceptable means for attaching the cover 10 to a surface
is a plurality of attachment openings 34 in the
peripheral flange 12 through which nails or the like may
pass to secure the peripheral flange 12 and the cover 10
to the surface. Preferably, each of these attachment
openings 34 is in the form of a slot, the slot having a
longer axis and a shorter axis. In such case, the longer
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axis is oriented towards the centre of the continuous
hollow body 14 to allow the continuous hollow body 14 to
expand and contract due to, for example, changes in
temperature, without compromising the secure attachment to
the surface.
The exhaust vent cover 10 also has a front 49,
a back 50, a left side 47 and a right side 48. The terms
front, back, left and right are used as above throughout
the description to describe the positions of the elements
of the present invention relative to one another.
The hollow body 14 has an air passageway 16
which communicates with an open front 18 of the body 14.
The open front 18 has a top 18a and a base 18b. An
overhang 20 extends beyond the top 18a of the open front
18. The outer surface of the hollow body 14 may include a
means for directing water away from the open front 18.
Two possible such means are shown on Figures 1 and 2 as
a projecting lip 31 and a water directing rib 30, both
located above the overhang 20.
The peripheral flange 12 has a three-part ridge
46 having a left part 46a, a right part 46b, and a back
part 46c. The left part 46a runs between the side 47 and
the left edge of flange 12. The right part 46b runs
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between the side 48 and the right edge of flange 12, and
the back part 46c runs between the back 50 and the back
edge of flange 12. The purpose of the ridge 46 is to
provide a sealing edge, against which roofing shingles may
be pressed. In this manner, water, such as rain or
melting snow which contacts the body, and runs down onto
the back or sides of the flange will be prevented from
moving laterally under the shingles, thereby preventing a
leak in the roof.
A valve is positioned within the continuous
hollow body 14 and across the air passageway 16. The
valve opens and closes the air passageway 16. The valve
is preferably in the form of a flapper valve 26 with a
pivoting end 42 and a free end 44. The pivoting end 42 is
mounted on a pivoting attachment on the inside of the body
14 and the free end 44 rests on a stop 32 when the flapper
valve 26 closes the air passageway 16. Preferably, the
flapper valve 26 is made from molded plastic and snaps
into pivoting engagement with the continuous hollow body
14. One form of pivoting engagement that is acceptable is
a hinge 40.
As shown, the hinge 40 is comprised of opposed
bearing posts 41a and 41b, which include opposed part
circular portions 43a and 43b. Because of the inherent
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resiliency of the posts 41a and 41b, they can be pressed
apart and a pivot bar or axle 45 formed on the flapper
valve 26 can be snap fitted into place.
The flapper valve 26 is opened and closed by
changes in the relative air pressure of the open front 18
and the exhaust vent. When the air pressure within the
exhaust vent is greater than the air pressure of the open
front 18, the flapper valve 26 opens, permitting
communication of the exhaust vent with the open front 18.
When the air pressure of the open front 18 exceeds the air
pressure within the exhaust vent, the free end 44 of the
flapper valve 26 is forced onto the stop 32 and the air
passageway 16 is closed. To ensure that the air passageway
16 is closed when the flapper valve 26 is forced onto the
stop 32, a valve seat 33 may be provided. When the flapper
valve 26 closes, an upper surface of the valve seat 33
matches a lower surface of the sides of the flapper valve
26 so as to prevent openings through which air may blow.
One problem that commonly arises with exhaust
vent covers is that the vent covers are prone to open and
close due to the influence of wind. The present invention
overcomes this through means for preventing the flapper
valve 26 from being blown open. One form this means may
take is that the flapper valve 26 has an air deflection
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surface which, when exposed to wind blowing through the
open front 18, deflects the wind upwards, causing the
flapper valve 26 to be forced down onto the valve seat and
the stop 32. This air deflection surface may be formed by
the end of the flapper valve 26 being sloped. For example,
the end of the flapper valve 26 nearest the open front 18
can be lower than the other end of the flapper valve 26 to
form the deflection surface which forces air blowing
through the open front 18 upwards.
Three orthogonal directions may be defined with
respect to the open front 18. A first direction, X,
extends laterally across the open front 18 between sides
47 and 48, and is substantially parallel to the base 18b
of the open front 18. A second direction, Y, extends
between the top 18a and the bottom 18b of the open front
18. A third direction, Z, is orthogonal to the first
direction X and the second direction Y and is normal to
the open front 18.
A grill 22 preferably covers the open front 18
to prevent access by small animals or foreign objects such
as leaves to the interior of the hollow body 14. The grill
22 may be formed by a plurality of ribs 36, and the stop
32 may include a lip below the grill 22 formed by the
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vertical ribs 36. The longitudinal axis of each of the
ribs 36 is parallel to the second direction. In this
embodiment, the free end 44 of the flapper valve 26 has at
least one tooth 38 that fits between the ribs 36 of the
grill 22 and that rests on the stop 32 when the flapper
valve 26 closes the air passageway 16.
Figure 2 shows an enlarged view of a portion of
Figure 1 containing the free end 44 of the flapper valve
26, a part of the grill 22 and the plurality of ribs 36,
as well as one of the at least one tooth 38 fitting
between two of the plurality of ribs 36. Each of the at
least one tooth 38 has a base 38b connecting it to the
rest of the flapper valve 26 and a crown 38a opposite to
the base 38b. The cross-sectional area of the crown 38a is
narrower than the cross-sectional area of the base 38b, as
the sides of the tooth 38 taper from the base 38b to the
crown 38a. This tapering ensures that when the flapper
valve 26 is lowered the crown 38a fits easily between the
vertical ribs 36 of the grill 22, but when the flapper
valve 26 is entirely shut, the base 38b fits relatively
tightly between the vertical ribs 36 in order to prevent
unwanted air leakage.
The sides 47 and 48 of the hollow body 14 extend
substantially beyond the open front 18. This further
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shields the grill 22 from the elements. Below the grill
22 and the open front 18, the continuous hollow body 14
has a front wall 56, which is slanted such that its lower
end is in front of its upper end. This facilitates
shedding water down away from the grill 22, when the vent
is installed, for example, on a sloped roof.
Figures 4 and 5 show an exhaust vent cover 110
according to a second embodiment of the present invention.
Similar to the first embodiment, the exhaust vent cover
110 includes a peripheral flange 112 surrounding the base
of a continuous hollow body 114, and the exhaust vent
cover 110 may be integrally formed from plastic. The
cover 110 has a front 149, a back 150, a left side 147 and
a right side 148 and the terms front, back, left and right
are used as above throughout the description of the second
embodiment to describe the positions of elements of the
present invention relative to one another.
As with the first embodiment, three orthogonal
directions may be specified with respect to an open front
118. A first direction, X', extends laterally across the
front 118 between a left side 147 and a right 148, and is
substantially parallel to a base 118b of the open front
118. A second direction, Y', extends between a top 118a
and the bottom 118b of the open front 118. A third
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direction, Z', is normal to the open front 118.
As shown on the diagram and except where
specified below, the elements of the second embodiment of
the present invention shown by Figure 4 correspond to
those shown by the first embodiment and are indicated by
the same number except that each of the numbers for the
elements of the second embodiment are preceded by a one.
The open front 118 of the second embodiment is
covered by a plurality of planar fins 162, each planar fin
162 having an front edge 162a and a back edge 162b. The
second direction, Y', is substantially normal to the
planes defined by the surfaces of the planar fins 162.
This alignment of the planar fins 162 prevents water
droplets from entering the open front 118 unless the water
droplets are moving in a direction substantially
orthogonal to the second dimension Y'. In addition, the
sides 147 and 148 extend beyond the open front 118,
preventing water moving substantially in the first
direction X', from impinging on the open front 118.
In order to penetrate the grill 122, water
droplets must be moving substantially parallel to the
third direction Z' such that the water droplets are moving
from the front of the body 114 to the back of the body
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114. However, as the cover 110 is usually installed on a
sloping roof such that the front edge 162a is lower than
the back edge 162b for the same fin 162, the motion of the
water droplets would have to include an upwards component,
against gravity, in order for the droplets to penetrate
the grill. Water droplets hitting the surface of the fins
162 will run down the surface of the fins 162 to the front
edge 162b and will fall off the surface of the fins 162
outside of the hollow body 114.
Preferably, the fins 162 are part of a front
piece 168, which is formed from molded plastic separately
from the exhaust vent cover 110, and is fitted into place
in the exhaust vent cover 110. In this embodiment, the
front piece 168 further comprises a base portion 170
extending forward from the base of the fins 162. Due to
the presence of the front piece 168, including the fins
162 and the base portion 170, the second embodiment lacks
the ribs 36 and the at least one tooth 38 present in the
first embodiment. The front piece 168 does include at
least three structural ribs 171, which help keep the fins
162 in place. It will be noted that the fins 162 are
wider (i.e. extend deeper into the body in the 2'
direction) at the top than at the bottom. This is to
allow for the free swing of the flapper valve through an
arc, without interference from the fins 64. Also, in lab
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tests, this configuration of fins prevented any
significant amount of water from penetrating the vent.
Water directed at the vent has a tendency to impact upon
the base 170, and deflect or splash upwards. Because the
fins extend into the body, and because of the angle of
incidence of the water on the base there are effectively
no open gaps between adjacent fins 162 for such deflected
water to penetrate the body. Thus any water splashing up
will strike a fin 162, attach to the fin by surface
tension, and eventually drain off the front. Thus
effectively almost no water can get in.
When installed on a conventional roof slope (22
31 ) it has been found that the fins as configured in Fig.
5 prevent water from entering the vent to an extent that
the flapper valve may not be necessary. Of course, in
colder climates where there is a concern about loss of
heat, the flapper valve is still desirable.
It will also be noted that the front piece 168
is essentially replaceable, if damaged or the like. To
install a front piece, the upper edge 180 is placed in
slot 182 formed on the underside of the top of the vent.
Then a stop 132 is rotated through the opening until lower
front wall 156 rides up and over a cam stop 184. The,
lower front wall 156 is retained between cam stop 184 and
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a stop ridge 186. This easy snap fit engagement provides
for a secure, yet easily replaceable grill.
From Figures 4 and 5 it is apparent that an
overhang 120 of the present invention according to the
second embodiment differs from the overhang 20. The
overhang 120 extends forward of the open front 118 and
down towards the peripheral flange 112, while the overhang
20 extends forward to a much lesser extent and does not
extend down at all. The more pronounced overhang 120
renders the water directing means less necessary and,
accordingly, neither the directing rib 30 nor the
projecting rib 31 have corresponding elements on the
second embodiment of the present invention. The overhang
120 preferably extends sufficiently to prevent rain water
from directly impinging on the grill 22.
It is believed that the overhang 120 also
contributes to preventing unnecessary opening and closing
of the flapper valve, in the absence of internal pressure
(i.e. by a fan or the like). Under some wind conditions,
a negative pressure may be created in front of the vent,
and a larger overhang contributes to preventing such a low
pressure from being direct enough on the flapper valve to
cause it to unseat.
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An alternative to using the stop 132 as a
resting point for the flapper valve 126, a pivot stop may
be molded into the vent cover behind the pivot hinge, as
shown at 190. This pivot stop will preferably be engaged
just before, or just as the flapper valve touches the lip
132, and will prevent the flapper valve from banging down
onto the lip. To make use of the pivot stop 190, requires
the flapper valve extend beyond the pivot axis, as shown
at 192.
Although the present invention has been
described with reference to preferred examples thereof, it
will be appreciated by those skilled in the art that
various alterations and modifications can be carried out
without departing from the scope of the invention. For
example, the following arrangement may be substituted for
hinge 140. A pivoting engagement may be formed by a bore
and shaft arrangement where the bores are part of the
continuous hollow body 114 and the shafts project out in
opposite direction from the opposite corners of the fixed
end 142 from the flapper valve 126. When the shafts are
snapped into the corresponding bores, the fixed end 142 of
the flapper valve 126 is attached to the continuous hollow
body 114, but the flapper valve 126 may rotate around the
axis substantially defined by fixed end of the flapper
valve 126 and the centre-line of the shaft and bore
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arrangement.
