Note: Descriptions are shown in the official language in which they were submitted.
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BLADE FOR A FAN, AND A FAN USING SUCH A BLADE
Field of the Invention
The present invention is directed to a blade for use in a high volume low
speed fan as
well as such a fan incorporating such a blade.
Background of the Invention
Within the present invention a fan shall be understood as a device, which is
suitable to
move air by rotating a plurality of blades around a hub/rotor such that the
blades will
cut the air more or less like an airplane propeller and in this manner induce
a velocity
to a mass of air. Consequently, the term blade shall be understood as the
object/member,
which projects from the rotor and travels through the air in order for the
profile and the
orientation of the blade, as it travels through an air mass, to introduce a
velocity to the
surrounding air.
Fans are very widely known for example as table fans, where the fans are
placed on a
table and due to the rotation of the blades, an air current is created for
example in order
to cool or to ventilate. Likewise, it is well-known to use fans in ceilings in
order to
create a draft in a room, whereby hot air collected under the ceiling will be
circulated
downwards into the habitable zone. Likewise, in areas where air condition is
widely
used, it is desirable to create air circulation in order for the cool air to
be circulated
around the entire habitable zone. Not in all circumstances will the air
condition unit be
able to distribute the cooled air and as such fans are used in order to create
extra venti-
lation.
In the field of fans one particular type of fan is the so-called high-volume
low speed
fans (HVLS), which are characterized by having a very large blade area and on
the other
hand rotate at a very slow speed. In this manner relatively large volumes of
air are being
moved without creating a draft, due to the relatively low speed which thereby
impart
motion to the ambient air. A draft is very undesirable, particularly for
persons working
in the habitable zone. It is this type of fan, i.e. HVLS fan the present
invention is directed
to.
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It is a general problem with large indoor areas/arenas, where a number of
persons are
working or otherwise spend time together to provide an environment with fresh
and
clean air without creating drafts or the spread of, for example contagious
diseases.
To this end it has been known to provide various disinfectant solutions such
as special
air cleaners or air treatment devices, where the air to be introduced into the
environment
has been disinfected prior to being introduced into the environment. The
disinfection
step may for example be the exposure of the air to heating and cooling UV-C
light or
other measures.
CN211778100U disclose an ordinary ceiling fan which has been provided with an
ul-
traviolet light source on an upper surface of the blade. Traditionally blades
of ordinary
fans travel with relatively high velocities, and as such the blades of the
fan, need not be
aerodynamically optimised. In the CN211778100U the ultraviolet light source is
mounted on top of the blade. This causes turbulence which again causes the
blades not
to impact so much air as if the air had not been disturbed. Furthermore,
turbulence also
creates noise.
Object of the Invention
It is the object of the present invention to provide a system, where already
used devices
for creating a suitable indoor climate are further enhanced by providing
additional ger-
mi ci dally effective features.
Description of the Invention
The invention addresses this by providing a high volume low velocity fan,
where said
blade has a profile, which profile when travelling through air will impart
motion to the
air, and where said blade has a front side surface and a back side surface,
said front side
surface and back side surface arranged between a leading edge and a trailing
edge,
where the leading edge and the trailing edge are arranged along a longitudinal
axis, such
that the blade in a cross-section orthogonal to the longitudinal axis has a
cross-section
and that integral inside said cross-section at least for a distance in the
blade along the
longitudinal axis, is provided one or more UV light sources, where said UV
light
sources are arranged to emit light away from said back side surface.
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A general problem with UV-C light is that it should not be directed directly
at persons
in that it might impair vision and create problems with the skins, as it has
been known
to be able to cause skin cancer and the like. Therefore, by providing the UV
light source
such that it emits light away from the back side of surface and this is also
the same as
saying that it emits light away from the habitable 70ne, it is avoided that UV
light is
emitted directly into the habitable zone. Furthermore, by integrating the
light source
inside the cross-section of blade the air dynamic characteristics of the blade
are not
altered and as such the blade may remain as effective as it was originally
designed to
irrespective of the fact that one or more light sources are integrated in the
blade. Partic-
ularly for HVLS fans it is important to maintain the aerodynamic properties,
such that
even though the blades travel through the air at a slow speed each blade will
be able to
effectively impart motion to the air. Therefore it is important that the
blades only moves
the air ¨ preferably in a downward direction, and disturbs the air as little
as possible (i.e.
does not create turbulence) during the blades motion through the air.
At least within the present invention the formulation "impart motion to the
air" shall be
understood as the blades during the sweeping motion through the air forces the
air in a
direction such that the air attains a velocity. The blade may achieve this for
example by
being angled with respect to the direction in which it is moving through the
air, or by
being provided with an aerodynamic profile which profile will cause the air to
move. It
should also be understood that the air direction/movement may be either away
from the
back side of the blade or towards the back side. There will, due to the
rotation of the
blade mounted in a fan also be a substantial cross-flow almost along the
blade. However
for the intent of the invention the air direction is not so important as long
as air is moved
into the zone where the UV light source emits light.
In a further advantageous embodiment of the invention the one or more UV light
sources
are arranged in a reflector, and where a transparent or translucent cover is
positioned
covering the UV light sources, such that said transparent or translucent cover
is integral
and/or flush with said back side.
It is clear that the provision of a reflector will concentrate the emitted
light in a specified
zone, such that the light emitted from the back side of the blade will be
concentrated in
the zone defined by the shape of the reflector. By furthermore covering the
light sources
with a transparent or translucent cover, the integration of light sources into
the blade
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will, as already discussed above, not have any influences on the blades'
aerodynamic
characteristics. The cover may typically be made from quartz glass but also
other types
of transparent or translucent cover may be used, for example plexiglass or
other mate-
rials, as long as they substantially allow the light to be emitted through the
cover mate-
ri al
In a further advantageous embodiment of the invention the one or more UV light
sources
extends 10 % to 100% of the length of the blade in the direction of the
longitudinal axis.
In order to have a germicidal effective effect the light source needs to emit
light with a
certain energy level in order to be able to destroy bacteria, virus and other
pathogens.
The destructive characteristic of UV-C light is created by deactivating DNA of
the bac-
teria, virus or pathogens. The UV-C light does not destroy the DNA but does
destroy
the ability of the DNA to replicate by causing damage to the nucleic acid of
microor-
gani sms by forming covalent bonds between certain adjacent bases in the DNA
struc-
ture. The formation of such bonds prevents the DNA from being unzipped for
replica-
tions and consequently the organism is unable to reproduce. Furthermore,
should the
organism try to replicate it will die due to the destruction of the DNA.
However, in order
to be effective, the bacteria, virus or the pathogens has to be exposed to a
certain dose
of ultraviolet light. For a blade being fastened to a rotor travelling through
an airmass,
the concentration or doses delivered to a virus, bacteria or other pathogen in
that airmass
obviously depends on the amount of watts emitted from the light source, the
time the
light source is present i.e. is radiating that particular virus, bacteria or
other pathogen
and furthermore the virus, bacteria or other pathogen distance to the light
source. All
these factors influence the success of the treatment and thereby how effective
the UV-
C light arranged on the back side of the blade is in disinfecting the air
through which it
travels.
Therefore, in some embodiments the extent of the blade and thereby the extent
of the
light source along the longitudinal axis of the blade allows for large areas
to be treated
as the blade travels through the air.
In another advantageous embodiment the one or more light sources extends 20 %
to
100% of the width between said leading edge and trailing edge.
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In a further advantageous embodiment, the one or more UV light sources are UV-
C
light sources having wave lengths in the interval from 100 nanometers to 300
nanome-
ters. Compared to the entire spectrum of unseen light and visible light 100-
300 nanome-
5 ters i s a very narrow band However, exposing ambient air to UV-C light
in such a broad
spectrum does, in addition to the germicidally effective part of the spectrum,
also intro-
duce some disadvantages. When oxygen is exposed to UV-C light below
approximately
250 nanometers the oxygen will be converted into ozone, which is detrimental
to an
indoor climate/environment. For this purpose, the ultraviolet spectrum, which
the pre-
sent invention emits, is in a further advantageous embodiment advantageously
limited
to UV-C wavelength from 253 nanometers to 300 nanometers. Particularly close
to 253
and 254 nanometers the wave lengths are particularly destructive for the
bacteria, vira
and pathogens, as described above.
One of the other factors having an influence on the effectiveness of the blade
is the
intensity of the emitted light. Typically, intensity is measured as irradiance
in W/cm2.
However safe exposures for human beings is measured in pW/cm2.With the present
invention where it is avoided that the UV lights emits light directly into the
habitable
zone, it is possible to use relatively strong UV lights without surpassing the
threshold
for damaging UV exposure. For this reason the irradiance from the UV-C light
sources
is limited to below 100 W/cm2. The high Wattage is used when LED lights are
used as
UV light source whereas for traditional low and high pressure UV lights the
wattage
may be in a much lower range of approx. 0,1 W/cm2.
In a further advantageous embodiment two or more light sources are arranged in
paral-
lel, and where a control unit provided either in or outside the blade controls
the light
sources such that one, two or more light sources may be active at a desired
time. With
this embodiment it is possible to adjust the emitted light both with respect
to area and
intensity such that for example in periods where no personnel are present in
the room,
in which it is desirable to disinfect the air, the intensity may be increased
in order to
thoroughly disinfect the air in the room, whereas in periods where the room is
filled
with personnel it might be disadvantageous to have the lights at high
intensity and the
fan at high speed. In these instances it is possible to increase the area but
lower the
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intensity and still maintain an effective germicidal effect by using the UV-C
light
sources in the blades.
In a particularly advantageous embodiment the blade is used in a high-volume
low
speed ceiling fan, where the blade will typically have a length along the
longitudinal
axis between 50 cm and 350 cm and/or the width orthogonal to the longitudinal
axis is
between 5 cm and 40 cm, and/or the thickness of the blade at the blades
thickest point
in a direction orthogonal to a plane defined by the longitudinal axis and the
width di-
rection is between 1 cm and 12 cm.
High-volume low speed fans are typically used in environments, where it is
desirable
to move large volumes of air at low velocities such that draft (the feeling of
a wind
blowing) is completely avoided but still the air is circulated in order to
keep a fresh and
a healthy indoor environment.
In a further advantageous embodiment, the UV light sources may be in the shape
of a
thin film applied to back surface of the plate, particularly in cases where
the light
sources are LEDs, this is a very advantageous embodiment.
LEDs tend to have a lower intensity than traditional low pressure or medium
pressure
UV lamps, and as such requires more space in order to be able to create
germicidally
effective doses.
Within this description thin film shall be understood as a very thin layer,
only fractions
of millimeters up to 2-3 mm thickness of a material in which LED light sources
are
embedded, or a thin film integrating the diodes. Such a film may be adhered to
the
surface or printed directly onto the surface of the blade.
In a further advantageous embodiment an aperture shield is provided covering
the UVC
light source, where said aperture shield is integral with the back side
surface of the
blade, and where the aperture shield is provided with one or more apertures,
allowing
the light to emit from the back side surface of the blade.
Many standard UVC light sources emit too concentrated a dose of UVC ¨ see
discussion
above about health and environment concerns. By positioning a aperture shield
having
one or more apertures in front of the light source, a physical limitation on
the emitted
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light is in place. Moreover, the one or more apertures may be designed/sized
such that
the desired dose of UVC light is allowed to be emitted. It is therefore
possible to use
the same type of light source for all applications. As the electronic
circuitry, light source
socket etc has to be adapted to the particular light source, it provides an
important ad-
vantage to be able to alter/control the emitted light by a simple mechanical
aperture
shield.
The invention is also directed to a fan, in particular a high-volume low speed
fan pro-
vided with at least one blade according to any of claims 1 to 9, where said at
least one
blade is arranged in a rotor, such that a motor may rotate the rotor and
thereby the blade
with a determined speed through the ambient air, whereby the back side of the
blade
passes a specified area per time unit and wherein a control unit is provided
wherein said
control unit comprises predetermined data correlating the blades speed through
the air
with the emitted light intensity, such that the air passing the back side of
the blade is
exposing the air to a germicidally effective light dose.
As already discussed above, it is necessary to assure that a certain dose of
UV-C light
is emitted in order for the light to be germicidally effective. However, with
the present
invention it is not necessary to kill 100% of any bacteria, virus or pathogens
with each
sweep, since the air is brought to move due to the action of the blades. The
air will be
circulating and as such the bacteria, virus or pathogens may due to the
turbulence cre-
ated by the fan pass the light zone, i.e. the zone where the lights are
emitting light above
the back surface, a number of times and as such over the course of some time
each virus,
bacteria or pathogen will be exposed to relatively high doses and as such an
effective
killing procedure will be achieved. In order to assure this, the fan is
provided with a
control unit, which has been preprogrammed, such that at the certain speed of
the blades
through the air, a certain light intensity will be emitted in order to assure
that a germi-
cidally effective light dose is emitted or transferred to the ambient air
adjacent the back
side of the blades. Again, this germicidally effective light dose may not be
100% effec-
tivefor each sweep of the blade through the air, as already mentioned above.
In a further advantageous embodiment, the fan has between 3 and 8 blades,
where each
blade is provided with features as disclosed in any of the claims 1-10. It is
clear that by
providing a fan, where 1, 2 or 3 blades for example are provided with light
sources and
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additional blades are not provided with light sources, the ability of the fan
to emit a
germicidally effective light dose is somewhat reduced. Therefore, by providing
all the
blades with light sources, a very effective zone is created above the blades,
where the
light dose continuously is germicidally effective. Furthermore, by being able
to rotate
the fan blades about an axis orthogonal to the longitudinal axis of the
blades, and
thereby circulate the air, the air will pass into the light zone many times
and as such
there will be ample opportunity to expose all bacteria and virus, or other
pathogen to
germicidally effective doses. In this manner, a very effective disinfection is
achieved.
Description of the Drawing
The invention will now be explained with the reference to the accompanying
drawing,
wherein:
figure 1 illustrates a blade according to the invention;
figure 2 illustrates a cross section indicated by AA(see figure 1)
perpendicular to the
longitudinal axis;
figure 3 illustrates a blade incorporated into a fan;
figure 4 illustrates a zone 38 in which the UV light sources due to the
rotation around
the vertical axis will expose the ambient air above the back side of the
blades to UV
light;
figure 5 illustrates a curve for a LED UV light source where the wavelength of
UV-C
light is on the X-axis and the intensity is on the Y-axis;
figure 6 illustrates a curve for a traditional low and medium pressure UV
light source
where the wavelength of UV-C light is on the X-axis and the intensity is on
the Y-axis.
Figure 7 illustrates various apertures shields suitable to be integrated in a
blade.
Figure 8 illustrates a mounting bracket.
Detailed Description of the Invention
In figure 1 is illustrated a blade 1 according to the invention. The blade 1
will, when
travelling through the air impart motion to air due to the air dynamic
profile, as will be
discussed with reference to figure 2. The blade has a front side surface 10
and a back
side surface 12. The surfaces 10, 12 are arranged between a leading edge 14
and a trail-
ing edge 16. The leading edge and the trailing edge 14, 16 are arranged along
a longi-
tudinal axis indicated by the dash line 18.
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The blade 1 is on the back side 12 provided with one or more UV light sources
20.
In this embodiment the trailing and leading edges 14, 16 are parallel and the
UV light
sources are arranged also parallel to the longitudinal axis 18. It is,
however, foreseen
that particularly the leading and trailing edges 14, 16 may have other
orientations along
the longitudinal axis depending on the air dynamic characteristics, which it
is a possible
or desirable to provide for the blade as such.
In figure 2 a cross section indicated by AA perpendicular to the longitudinal
axis 18
(see figure 1) is illustrated. The blade 1 has an air dynamic cross section
such that be-
tween the leading edge and trailing edge the back side 12 and the front side
surface 10
are provided with curved profiles such that as the blade 1 travels through the
air with
the leading edge 14 first, the air will be forced into motion, in this example
with the
cross section illustrated in figure 2, the air below the blade 1 will be
forced downwards.
Adjacent the leading edge 14 is provided a reflector 22 and two UV-C light
sources 20,
20'. As the light sources 20, 20' are activated, the light sources 20, 20'
will with the
help of the reflector 22 emit light emitting from the back side 12 away from
the blade 1
as such.
The blade, as discussed above with reference to figures 1 and 2 is
particularly suitable
for incorporation into a fan 2, as illustrated in figure 3. A number of blades
1 are fas-
tened to a rotor 30, where the rotor comprises a motor hub 32 and fastening
means for
example to a ceiling. In this manner the rotor 30 with the attached blades 1
may rotate
the blades around the vertical axis 34. As the blades are provided with a
cross section,
as discussed in figure 2, the rotation of the blades 1 around the vertical
axis 34 will
create a downforce i.e. the air will be forced downwards. Due to the blades
forcing the
air downwards, air will also move upwards in a big rotational movement, as
indicated
by the arrow 36. In this manner, air in a room, where a fan 2, as illustrated
in figure 3,
is installed, will be exposed to a slow circle of movement such that air on
one side of
the fan is forced downwards, whereas new air will be forced into the vicinity
of the fan
2, and as such be exposed to the sweeping action of the blades 1 forcing the
air down-
wards.
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This sweeping action particularly with respect to blades 1 wherein UV light
sources 20
are arranged, as mentioned above, will, as indicated in figure 4, create a
zone 38 in
which the UV light sources due to the rotation around the vertical axis 34
will expose
the ambient air above the back side 12 of the blades to UV light. In the
embodiment
5 explained with reference to figure 3 only one blade is indicated as being
provided with
UV light sources 20 but naturally one, two or any numbers of blades may be
provided
with UV light sources. In this manner, it is possible to regulate the
intensity of the light
in the zone 38, such that a germicidally effective dose of UV-C light,
particularly UV-
C light with a wavelength of approximately 254 nanometres (specifically 253,7
is de-
10 sirable) is created.
In figure 5 a curve for a LED light source is illustrated, where the
wavelength of UV-C
light is on the X-axis and the intensity is on the Y-axis. As indicated by the
dashed lines
the germicidal effectiveness of the light has an apex broadly between 256 and
268 na-
1 5 nom etres, where a particular light source (not necessarily the light
source used for the
present invention) has an apex in the area of 266 nm. As explained above, the
UV-C
light may have diametral effects, for example that it converts oxygen to ozone
and for
these reasons, it is desirable to select a wavelength, which is germicidally
effective and
at the same does not have any side effects. Therefore, with the present
invention wave-
lengths around 254 nanometres are selected.
Similarly to fig. 5 a curve for traditional low and medium pressure UV lamps
is indi-
cated in fig 6.
The type of UV-C light source may be decided according to how much space is
availa-
ble in the profile of the blade, see for example figure 2, the price of the UV-
C light
sources and also the desired intensity being emitted in order to create a
germicidally
effective dose in the vicinity of the back side 12 of the blade. For this
reason, traditional
low- or high-pressure UV lamps may be used but also LEDs may be used. If LEDs
are
used they may advantageously be attached to the back side 12 of the blade 1 as
a thin
film covering substantially the entire back side surface in order to be able
to provide
sufficient doses of the UV-C light but also providing a wide spectre of
intensity due to
the possibility of igniting sections of the LEDs or all of the LEDs according
to pre-
programmed parameters.
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In order to be able to provide different reductions in light intensity,
different aperture
shields may be used as illustrated with reference to figure 7. In this
embodiment the
aperture shields all have a standard size and may therefore be interchanged in
the same
recess/cavity provided in a blade as discussed above
The aperture shield 40 has a very narrow slit 42 corresponding to a 95%
reduction com-
pared to a situation where no aperture shield is provided in front of the UVC
light
source. Likewise, the aperture shield 44 has a slightly wider slit 46 which
provides a
900/0 reduction. The further aperture shield 48 having two parallel slits
50,50' provides
a 800/0 reduction and the further two examples 52, 54 provides 60 %, 40 %
respectively.
Naturally, the design of the aperture shields may be different and the slits
may be re-
placed by apertures or any other geometrical design as it is the size of the
opening which
is important with respect to the present invention in order to reduce the
emitted light
and adjust the light emission from the light source to a desired level in the
ambient
environment.
Furthermore as illustrated in fig. 8 a bracket construction 60 is provided for
mounting
the fan to a surface 62, for example a ceiling or as in this example the
underside of a
beam.
As ceilings may be provided at an angle relative to horizontal, it is
necessary that the
bracket 60 is able to orient a shaft 64 substantially vertically (as indicated
by dashed
line 66) in order for the blades of the fan (see fig. 3 or 4) to move through
the air in a
horizontal plane. The fan including motor, blades etc are attached to the
shaft 64.
The upper end 68 of the shaft 64 has a bulbous part (part of a ball). The
diameter of this
ball is larger than an aperture provided in a lower flange 70 of the bracket
60. In this
manner the shaft 64 may be inserted through the aperture, but the bulbous part
will not
pass. Due to the design of the bulbous part/ball shape the orientation of the
shaft 64
relative to vertical 66 and the lower flange 70 may easily be adjusted, such
that the shaft
is substantially vertical whereas the rest of the bracket may have any
(random) orienta-
tion dictated by the surface 62 onto which it is mounted.
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A fixation plate 72 is provided above the lower flange 70. This fixation plate
is provided
with a second aperture, such that the fixation plate 72 may be placed over the
bulbous
part and the bulbous part extend slightly, in use above the fixation plate 72.
By urging
the fixation plate 72 towards the lower flange 70, when fitted around the
bulbous part
68, the fixation plate 72 in combination with the lower flange 70 will fixate
the bulbous
part 68 when the fixation plate 72 is urged towards the lower flange 70.
Thereby, the
orientation of the shaft 64 is fixated in the desired orientation relative to
the bracket 60.
In order to urge the fixation plate 72 towards the lower flange 70, bolts 74
may be
arranged at desired positions around the periphery of the bulbous part 68,
such that when
tightening the bolts 74 the fixation plate 72 and the lower flange 70 will be
urged to-
wards each other, thereby squeezing/fixating the bulbous part 68.
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