Note: Descriptions are shown in the official language in which they were submitted.
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- IMPROVEMENTS_OF AIR DAMPERS
This inventions relates generally to dampers
for air systems, and has to do particularly with an
improved damper design utilizing an aluminum or other
light-metal extrusion for the damper blade itself. Even
more particularly, this invention relates to an extruded
damper design having high heat insulative properties.
BACKGROUND OF THIS INVENTION
-
Exemplary of the prior art is U.S. Patent No.
3,312,242, Kahn et al, issued April 4, 1967. In the Kahn
construction, individual damper blades are in the shape
of an air foil, with pointed edges, and designed to be
mounted on a central shaft having four longitudinal slots
at 90 intervals, into which four fingers internally of
the air foil construction are adapted to slide.
The prior art, however, contains numerous
examples, Kahn among them, of damper blade constructions
in which no or only minor heat insulative capacity is
present. In the case of Kahn et al, considerable heat is
lost directly from one side of the air foil shape to the
other, due to the large surface area of contact between
the extrusion and the central control shaft.
In view of the shortcomings of the prior art in
terms of providing adequate heat insulative capacity, it
is an aspect of this invention to provide an extrusion
adapted for use as a damper blade, which lends itself to
installations where heat insulative capacity is required.
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GENERAL DESCRIPTION OF THIS INVENTION
_
Accordingly, this invention provides, for use
as a damper blade, an extrusion which comprises two
spaced-apart face walls and two spaced-apart edge walls,
and two ridges projecting towards each other from the
face walls but having their inner edges spaced apart.
In another asp~ct, this invention provides an
insulated damper blade comprlsing a length of a
` light-metal extrusion having two parallel face walls and
two parallel edge walls in a parallelogram configuration.
Each face wall defines an obtuse angle with one edge wall
and an acute angle with the other edge wall. Two ridge
members project toward each other from the face walls but
have their inner edges spaced from each other. The
length of extrusion contains a heat-insulative material.
GENERAL DESCRIPTION OF THE DRAWINGS
~ . . . _ . _ . .
One embodiment of this invention is illustrated
in the accompanying drawings, in which like numerals
denote like parts throughout the several views, and in
which:
Figure 1 is a sectional view of an extrusion
suitable for forming the damper blade of this invention;
and
Figure 2 is a vertical sectional view through a
damper assembly utilizing a plurality of dampers made
with extrusions of the kind shown in Figure 1.
DETAILED DESCRIPTION OF TH~ DRAWINGS
Figure 1 shows a cross-section of a suitable
extrusion of aluminum or other suitable material,
particularly adapted for use with this inven-tion. As
seen in Figure 1, the extrusion generally shown at 10
includes two parallel face walls 12 and 13 and two
parallel edge walls 15 and 17 in a parallelogram
configuration. Each face wall 12, 13 defines an obtuse
angle with one edge wall and an acute angle with the
other edge wall. More specifically, the upper face wall
12 defines an acute angle ~ with -the edge wall 15, and
defines an obtuse angle ~ with the other edge wall 17.
Likewise the bottom face wall 13 defines an acute angle
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o~ with the edge wall 17 and defines an obtuse angle
with the edge wall 15. In Figure l the point 20
designates the center of gravity of the cross-section of
the extrusion 10, and it can be seen that each of the
face walls 12 and 13 has a ridge member 22 and 24,
respectively, each of which it is arranged
perpendicularly with respect to its respective face wall.
The two ridge members 22 and 24 are in alignment and the
central plane of the two ridge members substantially
intersects the center of gravity location 20.
Each face wall 12 and 13 has an extended
portion, numbered 25 and 27 respectively, each extended
portion projecting beyond the edge wall with which its
particular face wall defines an acute angle.
As further seen in Figure l, the edge wall 15
has, on its outside surface, integral track~defining
means for receiving two resilient sealing strips. More
particularly, the edge wall 15 defines two upstanding
C-shaped structures 30 which define T-shaped slots
adapted to receive resilient extrusions, such as the
extrusion 32 shown in Figure 1. It is to be understood
that a similar extrusion would be provided in the upper
track-defining means ~0 as well. The resilient sealing
member 32 may advantageously be made of PVC or similar
soft plastic material.
Attention is now directed to Figure 2, showing
a damper installation generally at the numeral 33. The
installation 33 includes a frame 34 which need not be
described in detail as the construction of the frame per
se does not form a part of this invention. The frame 34,
however, does include upright frame members 36 (of which
one is seen in Figure 2), top and bottom frame members 38
and 39, respectively, and two horizontally extending
damper blade stops, one extending downwardly from the top
frame member 38 and numbered 40 t the other extending
upwardly from the bottom frame member 39 and numbered 42.
As can be seen in the Figure, each damper blade stop 40
and 42 is welded or otherwise secured to a flange 44
extending from the mid-point of the respective horizontal
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frame member 38 and 39. The upper damper blade stop 40
is provlded with track-defining means 47 similar in
construction to the track-defining means 30 shown in
Figure 1, and adapted to receive similar or identical
resilient sealing members 48.
In the construction shown in Figure 2 three
control shafts 50a, 50b and 50c are shown, extending
horizontally between the side frame members 36. As can
be seen in both of thèse Figures, each control shaft has
two opposed slots 52 and 53 which are adapted to
slidingly receive the ridge members 22 and 24,
respectively, in order to mount the individual damper
blades.
In Figure 2, there are three damper blades lOa,
lOb and lOc mounted on the control shafts 50b and 50c.
All of the damper blades are identical, and between the
damper blades lOa and lOb has been drawn the
configuration of those two damper blades when each has
been rotated in the clockwise direction to approximately
90, in order to bring the sealing members 32 of the
damper blade lOa into contact with the edge wall 17 of
the damper blade lOb.
In order to rotate all three damper blades in
tandem, a conventional parallelogram linkage is provided,
this incorporating a vertical shaft 53, having adjustable
connectors 54 mounted at intervals therealong, each
connector 54 being pivoted to one end of a bracket 56
which is affixed near one end of the respective damper
blade lOa, lOb and lOc. As is customary and evident from
Figure 2, each pair of adjacent damper blades, along with
the frame 34 and the shaft 53, constitutes a swivelling
parallelogram. By raising the shaft 53, the damper
blades can be made to move in the clockwise direction to
close the opening defined within the frame 34. ~n the
closed position, the edge face 17a of the upper damper
lOa seals against the sealing members 48 supported on the
damper blade stop 40, while the sealing members 32c on
the lower damper blade lOc seal against the lower damper
blade stop 42.
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The internal cavity within each of the extruded
damper blades is filled with a suitable heat-insulative
material 58, which may conveniently be styrofoam
(expanded polys-tyrene) or the like.
At the ends of the aluminum extrusions
constituting each damper blade, the extrusion is
conveniently "closed in" by applying a sealing compound
against the exposed insulative material. A suitable
material is the duct sealant sold under the name
"tough-bond" by Trans Continental Equipment Ltd.
It will be evident that in the damper blade
construction provided herein, the transfer of heat from
one face wall to the opposite face wall of each damper
blade is minimized, due to the presence of the
heat-insulative material within the damper blade, and due
to the minimization of the area of metal along which heat
can be transferred. It is well known that aluminum is a
good heat conductor. It is therefore important to
restrict the cross-sectional area of the aluminum
available for heat transfer to the least possible,
consistant with sufficient strength. By spacing the face
walls of the extrusion away from the control shaft, and
by mounting the extrusion to the control shaft by the use
of flanges 22 and 24, any heat transfer is forced to
follow a restricted path, and therefore is minimized.
The extended portions 25 and 27 of the
extrusion permit the resilient sealing members 32 to be
protected from adverse weather effects, for example snow
and rain, when the damper is in the closed positlon.
Also, if the damper where to be used as a combination
louvre-damper, the extended portions 25 and 27 would act
as a dripsill, allowing water and melting snow to drip
off each blade in such a way that the sealing members 32
do not contact moisture. It will be understood that any
build-up of snow or ice on a PVC seal could affect
adversely the tight closing characteristics of the
damper.
While a specific embodiment of this invention
has been illustrated in the accompanying drawings and
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described hereinabove, those skilled in the art will
appreciate that changes and modifications may be made
therein without departing from the essence of the
invention as set forth in the appended claims.
