Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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Heating fan
Field of the Invention
The present invention relates to a heating fan.
Background of the Invention
In the art there are a large number of fans for circulating or moving air.
A special segment of all these fans is provided with heating means such that
as the fan is
activated the air which the blades/wings of the fan engage will be heated
thereby increasing the
overall room temperature. Examples of fans incorporating heating means are
found in US
2009/0116961, US 4504191, US 449414.
A common problem with fans of this type is the ability to transfer heat from
the heating
elements to the air which comes into contact with the blades and at the same
time distribute
the air more evenly around the room than just in front or below the fan blades
which will
otherwise be the case. These problems have unsuccessfully been addressed in
the art, for
example in US 4867643, US 2006/0110257.
Although some of the prior art documents realize that in order to be able to
transfer heat from
a heating element arranged on a blade on a fan of the type mentioned above it
is desirable to
create turbulence adjacent the wing blades. The means for creating the desired
turbulence
often conflicts with the desire to be able to distribute the heated air to a
larger area or to
minimize the energy necessary in order to rotate the blades at a speed where
the air put in
motion by the blades may be able to reach further than just in front of the
fan.
Object of the Invention
Consequently, it is an object of the present invention to provide a fan which
addresses the
problems in the prior art and at the same time provides further advantages.
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Description of the Invention
The invention addresses this by providing a heating fan, where said fl
means for fastening of said fan to a first surface, a stem connecting the
fastening means to a
hub, where said hub comprises a motor unit, where said motor unit rotates a
plurality of wings
extending radially from said hub, such that the wings have an upper and a
lower surface,
characterised in that each wing has a leading and trailing edge, defining
upper and lower sur-
faces there between where at least one wing has electrical heating means
integrated or
connected to said upper surface, where at least more than half the length of
the leading and/or
trailing edge is bent downwards relative to the surface of the wing.
By simply bending an area adjacent the leading and trailing edges of the blade
slightly out of
plane relative to the main area of the surface of the wing, turbulence is
created across the
surface of the wing whereby optimal heat exchange properties are created in
front of the
heating element arranged on the surface of the wing.
At the same time the main area of the wing is maintained relatively flat such
that the
engagement with the air to be moved is relatively high whereby an effective
air distribution is
effected.
In a further advantageous embodiment of the invention the wing profile in a
cross section
perpendicular to the radial extent of the wing relative to the hub comprises
three distinct
substantially linear sections, a first linear section extending between 5 to
25 mm from the
leading edge and a second linear section extending between 5 to 25 mm from the
trailing edge,
and a third linear section arranged between the first and second sections,
where said third
linear section has an extent between 35 and 110 mm, where the first and second
linear sections
are angled 5 to 60 relative to the third section.
The actual dimensions recited in this embodiment ensures that sufficient
surface space is pro-
vided for the heating element such that a substantial amount of energy may be
provided for the
contact zone between the air and the wing and at the same time enough wing
area is provided
in order to move the air coming into contact with the heating fan. The bent
sections solely
serve to create turbulence in order to optimize the heat exchange capabilities
between the sur-
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heat exchange capabilities between the surface of the fan blade and the
into contact.
In a still further advantageous embodiment of the invention the heating means
is provided by
metal leads having an Ohm-resistance of approximately 40 C2. or more, where
said metal leads
are embedded in a thick film heat distributing lacquer layerpreferably
containing glass.
Although as already elaborated in the prior art and as mentioned above it is
important to
create turbulence adjacent the surface of the blade in order to create optimum
heat exchange
capabilities between the heating element and the air which is desired to be
heated, it is also
important to provide sufficient heating means on the surface such that a large
amount of
energy may be transferred from the heating element to the air. Tests indicate
that a turbulent
air flow across a surface increases the heat exchange by approx. 40 % as
compared to a
laminar airflow.
Naturally, this increases the efficiency of the heating fan which is a
desirable feature. There-
fore, in order to provide the present invention with as large a heating
surface as possible the
leads are evenly distributed on the surface, and in order to further
redistribute the heat the
thick film layer will distribute the generated heat substantially evenly
across the entire surface
of the heating fan blade.
A suitable material is "insulating composition 4924" available from ESL
electro-science, USA.
This paste is applied in a silk-screen process in the desired layer thickness
as indicated by the
manufacturer. The paste comprises ultra-micro glass particles/balls which
provide the special
characteristics making it especially suitable for the present application.
An important aspect with the material is that the thermal characteristics
substantially corre-
spond to the base material, which typically may be stainless ferritic steel.
In this manner
undesired cracks in the heat distributing thick-film layer is minimised or
altogether avoided, as
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gether avoided, as the material is able to move with the steel during opi
heating and cooling causing thermal expansion of the steel member maki
An actual wing construction used in the development of the present invention
was made from
stainless steel. A first layer of di-electric "insulating composition 4924"
was applied. The layer
was placed in an oven and the layer hardened. Thereafter an electrical lead
made from a thick
film silver palladium material was arranged on the surface (as illustrated in
fig. 2), and
thereafter hardened. Finally a further very thin layer of "insulating
composition 4924" was
placed and cured. The top layer being so thin as being substantially
transparent
Typically, the blades used with the present invention will be made from a
metal, often regular
steel, and as the heat is generated by means of the resistor heating element
provided on the
surface of the blade, the blade itself will also heat up. This heating will
cause thermal
expansion and by selecting the thick layer lacquer appropriately it is
possible to select a
lacquer which has substantially the same thermal expansion coefficient as the
steel, such that a
coherent surface without cracks will be provided. In this connection it is
important that cracks
do not occur in that this will be detrimental to the heat distribution and
thereby the effective
area of the blade which is able to transmit heat from the source of energy
through the heating
element and through the air which it is desirable to heat. Therefore, by
selecting appropriate
materials such that the heat is substantially evenly distributed across the
entire surface of the
blade and at the same time as the material from which the blade is made heats
up and thereby
expands the heat expansion coefficient of the thick lacquer layer shall be
selected such that
cracks are avoided, or at least minimized.
The surface of the blades may be provided with means such as dimples, ridges,
grooves, or
other unevenness in order to increase the turbulence creating capability of
the blade. In this
manner the heat transfer capability between the blades and the ambient air is
increased.
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In a further advantageous embodiment the hub comprises a collector w
electrical power from the stem/hub to at least one heating element anal
the plurality of wings, where said collector comprises a central non-
conductive member, where
at least a first and a second conductive member is arranged about said central
non-conductive
5 member, where non-conductive means are arranged between said first and
second conductive
members, and where first and second blade means are arranged for conductive
contact with
first and second conductive members respectively, and where said first and
second blade
means comprises means for a conductive connection to the heating means
arranged on the
wings.
Another important requirement of a heating fan is its ability to transfer
energy to the heating
element arranged on the blades. The present invention therefore provides a
collector arranged
in the hub such that as the blades rotate around the hub energy will still be
transferred to the
heating elements on the blades. By providing a relatively large surface
between the rotating
part and the stationary part it is possible to transfer relatively large
amounts of energy such
that the heating elements compared to prior art devices are able to reach a
higher temperature
and due to the turbulent conditions immediately above the heating element to
transfer more
energy through the air such that better heating is achieved.
The relatively large area is achieved by having the first and second blade
means engaging
surfaces on the first and second conductive members such that instead of a
conductive member
being in contact with the edge of the first conductive member as is the case
in a dynamo or
other stator-rotor arrangements, the blade's increased surface provides the
possibility to
transfer more energy.
At the same time, as the mechanical force between the blade and the first
conductive member
is distributed over a larger area the mechanical wear/abrasion between these
two parts is much
less than what is customary with normal arrangements.
In a still further advantageous embodiment the collector may be provided with
any number of
power transfer surfaces simply by alternating the constniction such that a
conductive blade
member is in rotatable contact with a conductive means and that non-conductive
means are
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conductive means are interposed between the conductive arrangeme
becomes possible to provide even more energy to more blades there]
heating fan more effective.
In order to accommodate the electrical leads necessary for the transfer of
energy to the blades
and the resistive heating element arranged on the blade the central non-
conductive member is
symmetrical about a central axis, and the non conductive means are integral
with the central
member, and furthermore electrical leads may be arranged in the central non
conductive
member and brought into electrical contact with the conductive members.
Description of the Drawing
Figure 1 illustrates a ceiling mounted fan
Figure 2 illustrates a blade according to the invention
Figure 3 and 4 illustrate collectors according to the invention
Detailed Description of the Invention
In figure 1 is illustrated a ceiling mounted fan where the fan 1 by fastening
means 2 is attached
to a ceiling 3. A stem 4 connects the fastening means 2 to a hub 5. The hub
comprises motor
means for rotating the blades 6 as well as collector means for distributing
electrical power to
the heating means arranged on the blades 6. In this manner as the heating fan
is energized the
blades 6 will rotate on an axle substantially parallel to the stem such that
the blades 6 will
come into contact with the surrounding air and due to the energy exchange
between the
heating element positioned on a surface of the blade 6 heat will be
transferred to the air and
due to the position of the blades 6 the air will be propelled in this
embodiment downwards.
The downwards air movement will create under-pressure above the blades such
that air will be
pulled into and towards the blades. In this manner circulation of
substantially all the air in a
closed room may be achieved.
A critical and important aspect of the invention is the ability to transfer
heat from the heating
element arranged under blade 6 to the surrounding air.
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In figure 2 is illustrated a blade according to the invention. The blade
sections 10, 11, 12. In this embodiment the sections 11 and 12 are arra]
leading edges 13, 14 and are substantially identical. The surface between the
sections 11, 12 is
covered by a thick film lacquer layer 15 in which is embedded a resistance
heating element 16.
As energy is provided in the form of electricity to the heating element, i.e.
the combined
lacquered surface 15 and the heating element 16 covering substantially all of
the section 10
will heat up. As the blade 6 is rotated having either the edge 13 or 14 as
leading edge and the
other as trailing edge air will due to the angle between the section 10 and
the sections 11, 12
pass across the surface 10 not as a laminar flow but as a turbulent flow due
to the angled
sections. In this manner the heat exchange between the heating element
arranged on the
surface 10 and the air which the blade 6 passes due to its rotation will be
greatly improved
such that more energy may be provided by the heating fan.
In figure 2 is illustrated a fan blade having a cross section with two
substantially equally sized
leading and trailing sections 11, 12 respectively, but they may have different
extent and also it
is contemplated that only part of the edges 13, 14 may be provided with
sections 11, 12 turned
out of the plane of the remaining surface 10.
However, the blade illustrated in figure 2 has proven to be extremely
effective in that tests
were repeatedly carried out in a room where it was desirable to elevate the
temperature from
approximately 6 C to 20 C. The room has the size of approximately 4x5 metres
and
approximately 3 metres to the ceiling. After the temperature of 6 C had been
registered the
fan was turned on. The power consumption of the heating fan was adjusted to
maximum level
throughout the entire period of heating and after 13-16 minutes of rotating
the fan at
maximum power, the room temperature had increased from 6 C to 20 C. The
heating fan used
for this test had three blades arranged evenly around the perimeter of the hub
where each
blade was approximately 38 cm long and the first and third sections were
approximately 10
mm, such that the central surface 10 on which the heating element 16 was
arranged at an area
of approx. 9 cm by 25 cm. The blades were made from a standard steel blade
approximately
1.5 mm thick. The room temperature was measured approximately 1 meter above
the floor at
a location approximately 2 metres from the axis of the stem of the heating
fan.
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Furthermore, tests indicate that each blade as described above is able tt
Watts. Having three blades, the electric energy necessary to produce the
maximum power will
cause normal household circuitry to blow the fuses. The control electronics in
the fan may
therefore be programmed to only allow the blades to produce less power, or
alternatively the
blades shall be connected to a more powerful source of electricity.
The fans may furthermore be designed to the specific geographic conditions
where they are
used. For example in European Mediterranean countries the normal fuse size is
6 Amp
whereas in northern Europe/Scandinavia 10 or 16 Amp fuses are used. Therefore
the wattage
which the fan may produce is adapted accordingly.
Another very important aspect with heating fans of this type is the ability to
transfer power to
the heating element. The present invention has solved this with a collector as
illustrated in
figure 3 The collector 20 comprises a first and non-conductive core member 21
which serve
to isolate first and second conductive members 22, 23. The first and second
conductive
members 22, 23 are in the shape of rings made from a metal or metal alloy, for
example
copper or the like.
The insulation core 21 may be made from any suitable non-conductive material
such as for
example plastic, ceramic or the like. The non-conductive core member is
symmetric such that
the conductive members 22, 23 preferably are in the shape of rings. The non-
conductive core
member 21 and the rings 22, 23 are stationary such that the first and second
plate members 24,
25 may be rotated relative to the conductive rings 22, 23. In this manner the
surfaces facing
each other of the ring members 22 and plate member 25 respectively and the
ring member 23
and plate member 24 respectively provides for an electric connection between a
stationary part
22, 23 and the rotatable parts 24, 25. The interface surface between these
conductive parts is
relatively large such that substantial amounts of electricity may be
transferred during rotation
of the heating fan. The plate members 24, 25 are provided with a copper layer
in order to
ensure electric conductivity with as little resistance as possible.
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The blade members 24, 25 are urged towards each other, for example
illustrated).
The electricity is supplied to the ring members 22, 23 by means of electrical
leads 26, 27 hay-
ing opposite polarity.
In many domestic power installations fuses will limit the amount of
electricity/power which it
is possible to transmit through a single socket. In these instances the
collector as illustrated in
figure 3 will usually be sufficient in that it is not the blade 6 nor the
collector which limits the
amount of power available, but the domestic electrical installation.
In other instances more power is available from the installation and in these
installations it may
be desirable to use a three-phase electrical connection with a collector being
able to transfer
power from such a three-phase installation. Such a collector is illustrated
with reference to
figure 4. The collector in figure 4 comprises all the elements of the
collector illustrated with
reference to figure 3 but has an additional set of conductive members 28, 29
such that each
electrical phase will have dedicated conductive members for the transfer of
power from the
stationary to the rotational parts.
Naturally the number of blades in any fan construction may be installed
according to the
individual desires. Also the type of electrical connection serial or parallel
or a combination may
be utilised when connecting fans within the scope of the present invention,
without departing
from the inventive principle.
Obviously, the collector may be expanded to include further sets of conductive
and non-
conductive elements depending on the number of electrical leads desirable to
be providing
power for the heating elements 16 provided on the blades 6.
