Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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DRYING APPARATUS COMPRISING A FILTER
The present invention relates to drying apparatus. Particularly, the invention
relates to
drying apparatus including a filter unit for removing particulates and
bacteria from a
waste liquid such as water.
Conventional arrangements for collecting and removing waste water from drying
apparatus such as hand dryers are well known from, for example, US 5,459,944.
Waste
water is collected via a duct or similar and transferred to a drip collector
for subsequent
manual removal. Such storage of waste water is unhygienic, may lead to the
spread of
bacteria and requires regular maintenance to empty the drip collector and
maintaiil a
sanitary environment.
The addition of an antibacterial water absorption sheet with a large surface
area to
encourage evaporation is known from JP 11-18999 A. This counters some of the
problems of bacterial infestation and results in less frequent emptying of a
water
collector. However, particulate matter will be deposited on the sheet, and
this will affect
the petfon.nance of the machine over time and require frequent cleaning.
It is an object of the present invention to provide drying apparatus which is
capable of
filtering and sterilising liquid more efficiently and reliably than prior art
apparatus.
The invention provides drying apparatus comprising an outer case, a portion of
the outer
case defining a cavity in which articles can be dried, an outlet disposed at
the lower end
of the cavity and a filter unit arranged downstream of the outlet, wherein the
filter iulit
comprises a particulate filter and a sterilising filter. By providing a filter
unit comprising
a particulate filter and a sterilising filter, solid matter and bacteria can
be removed from
the waste liquid. This results in a hygienic and sanitary waste liquid output
from the
filter unit.
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Preferably, the sterilising filter is located downstream of the particulate
filter. By this
arrangement, the particulate filter can remove some solid material and larger
particulates from the waste liquid to prevent the ster.ilising filter from
clogging.
Preferably, the filter unit further comprises flow directing means for guiding
liquid
through the filter unit. By providing flow directing means, the liquid can be
directed to
flow through the sterilising filter. The flow directing means allow efficient
use of the
sterilising filter ensuring that the water leaving the filter unit has been
sufficiently
treated.
An embodiment of the invention will now be described with reference to the
accompanying drawings, in which:
Figure 1 a is a perspective view of a hand dryer according to the present
invention;
Figu.re Ib is a side view of the hand dryer of Figure 1 a;
Figure 2 is a section through the hand dryer of Figure 1 a showing a filter
unit;
Figure 3 is an enlarged version of part of Figure 2 showing the internal
workings of the
hand dryer and the filter unit in greater detail;
Figure 4 is a perspective view of a liquid treatment module including the
filter unit
removed from the hand dryer of Figure 1 a;
Figure 5a is perspective view from above of the hand dryer of Figure la
showing the
liquid treatment module partially removed from the hand dryer; and
Figure 5b is a perspective view from below of the hand dryer of Figure 1 a
showing the
liquid treatmerit module partially removed from the hand dryer.
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Figures 1 a and lb show a hand dryer 10 according to the present invention.
The hand
dryer 10 inchides an outer case 12, a front wall 14a, a rear wall 14b, two
side walls 14c,
14d and a cavity 16. The rear wall 14b may include elements suitable for
attaching the
hand dryer 10 to a wall surface or other suitable fixture. Elements for
connecting the
hand dryer 10 to a power source may also be included.
The cavity 16 is defined by opposing arcuate front and rear walls 16a, 16b.
The cavity
16 is open at its upper end 18, and the dimensions of the opening are
sufficient to allow
a user's hands (not shown) to be inserted easily into the cavity 16 for
drying. A high-
speed airflow is generated by a motor unit having a fan (not shown). The motor
unit and
fan are located inside the outer case 12. The high-speed airflow is expelled
through two
slot-lilce openings 20 disposed at the upper end 18 of the cavity 16 to dry
the user's
hands. These features are not material to the present invention and will not
be described
any further here. The cavity 16 is open at the sides as can be seen in Figures
1 a and lb.
As can be seen from Figure 2, a drain channel 22 is located at the lower end
24 of the
cavity 16. The drain channel 22 is delimited by the lower edges of the front
wall 16a
and the rear wall 16b of the cavity 16 and slopes downwardly towards one side
of the
cavity 16. An outlet 26 is located in the drain channel 22. The outlet 26 can
take any
suitable form. In this embodiment, it comprises a circular aperture with a
central plug
26a. The outlet 26 and plug 26a delimit a narrow, annular opening.
Referring to Figures 2 and 3, a chamber 40 is formed in a lower part of the
outer case 12
below the cavity 16. The chamber 40 is delimited by a plurality of chamber
walls 40a
and has an open lower end. A liquid treatment module 30 is located in the
chamber 40
and is held in place by clips, quarter turn fastenings or other fastening
means (not
shown).
Referring to Figures 3 and 4, the liquid treatment module 30 includes a filter
unit 200.
The filter unit 200 is designed to filter particulates and impurities from the
water, and to
ldll bacteria in the water. A filter inlet 202 is located at the upper end of
the filter unit
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200 and coirununicates with the outlet 26. A sump 204 is located downstream of
the
filter inlet 202. The sump 204 has a base 204a. A wall 206 of the sump forms a
weir
206a. The height of the weir 206a determines the inaximum level of liquid that
can be
contained within the sump 204. A filter outlet 208 is delimited by the weir
206a, the
wal1206 of the sump 204 and the outer walls 210 of the filter unit 200. The
filter outlet
208 provides an outlet for water flowing over the weir 206a:
A partition 212 extends from the upper portion of the filter unit 200 adjacent
the filter
inlet 202 into the sump 204. The partition 212 extends partially into the sump
204 such
that the distal end 212a of the partition 212 is spaced from the base 204a of
the sump
204. The partition 212 is arranged such that the volume of a first region 204b
of the
stunp 204 beneath the filter inlet 202 is greater than a second region 204c of
the sump
204 adjacent the weir 206a.
A sterilising filter 214 is located at the base 204a of the sump 204. The
sterilising filter
214 consists of particles of an iodine-loaded resin. The resin is loaded at a
concentration
of 500 g/l. In this einbodiment, the volume of the sterilising filter 214 is
50 ml. The
iodine-loaded resin acts as a sterilising compound to lcill any bacteria
present in the
water. The particles of the sterilising filter 214 are substantially spherical
and have
dimensions in the range of 0.1 to 2 mm (average particle size 0.8 mm). The
sterilising
filter 214 is dimensioned such that the distal end 212a of the partition 212
extends
partially into the sterilising filter 214.
A particulate filter 216 is located above the sterilising filter 214 and
comprises glass
beads with diameters of 4 mm. The particulate filter 216 is located on top of
the
sterilising filter 214 in the first region 204b beneath the filter inlet 202
which is bounded
by the partition 212 and the sump 204. The particulate filter 216 has a
voluine of 10 ml.
Further, the particulate filter 216 operates as a pre-filter, preventing
larger particles of
solid matter (in particular soap) from blocking the sterilising filter 214. In
order to
improve performance, the area of the bed of the particulate filter 216 and
sterilising
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filter 214 is maximised. A large bed area reduces the pressure drop across the
filters and
increases the resistance of the filters to fouling and becoming blocked.
Both the sterilising filter 214 and the particulate filter 216 are located in
the sump 204
5 below the maximum level of liquid that can be contained in the sump 204.
This means
that, once the level of liquid in the sump 204 has reached the maximum,
operational,
level, the sterilising filter 214 and the particulate filter 216 are
completely submerged in
the water. This is beneficial because the sterilising filter 214 is prone to
cracking and
forming air pockets if it is permitted to dry out once it has become wetted.
By keeping
the sterilising filter 214 continuously wetted, this problem is avoided. In
addition, this
configuration ensures that the water flow is well distributed. Further, the
maximiun
level of liquid should be far, enough above pa.rticulate filter 216 to allow
the head of
water to apply pressure on the bed of the filters.
The liquid treatment module 30 further includes a liquid dispersion unit 35
located
below the filter unit 200. The liquid dispersion unit 35 is arranged to
receive water from
the filter outlet 208. An exhaust conduit 37 located within the liquid
dispersion unit 35
provides a communication path from the liquid dispersion unit 35 to the
outside of the
outer case 12 of the hand dryer 10. The liquid dispersion unit 35 fiuther
includes a
collector 100 for collecting water from the filter outlet 208. The collector
100 has a base
100a. A high frequency agitator in the form of a piezo-electric device 102 is
located at
the base 100a. A fan 104 is supported on one of the chamber walls 40a. The fan
104 is
located outside the chamber 40 separate from the liquid treatinent module 30.
The fan
104 is configured to direct an airflow into the collector 100 through an
aperture 38
provided in the liquid treatment module 30.
In use, the water removed from a user's hands during the drying process flows
down the
front wall 16a and the rear wall 16b of the cavity 16 and into the drain
channel 22
disposed at the lower end 24 of the cavity 16. The drain channel 22 collects
and guides
the water towards the outlet 26.
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Upon entering the outlet 26, the water passes into the filter unit 200 through
the filter
inlet 202 (see arrow A). The water falls onto the particulate filter 216
(arrow B) and
spreads evenly across the surface of the particulate filter 216. As the water
rnoves down
through the beads of the particulate filter 216 under the influence of
gravity, larger
particles of dirt and debris will be left behind iri the particulate filter
216. When the
water reaches the sterilising filter 214 (arrow C), the majority of the solid
particulates in
the water will have been removed by the particulate filter 216.
The sterilising filter 214 sterilises the water by deactivating bacteria in
the water. The
iodine-loaded resin releases iodine into the water at a rate of 1 to 5 parts
per million
(ppm). Iodine is a strong oxidant and hence acts as broad spectrum
antimicrobial. The
water flows down through the sterilising filter 214, is sterilised and is then
deposited in
the bottom of the sump 204. This process continues and the voluine of water
collected
in the sump 204 increases until it reaches the maximum level permitted by the
weir
206a. Up until this point, the water levels either side of the partition 212
experience an
equal force due to atmospheric pressure. However, if more water is introduced
through
the filter inlet 202, the increased head of water in the first region 204b
will cause an
imbalance in the forces acting on the water levels either side of the
partition 212. The
effect of this is for the mass of the added water to apply a force downwardly
on the
water in the sump 204. This causes a net movement of water in the direction
shown by
the arrow D. The partition 212 directs the flow of water down towards the base
204a of
the sump 204, down through a part of the sterilising filter 214 located in the
first region
204b of the sump 204, and back up through another part of the sterilising
filter 214
located in the second region 204c of the sump 204 to the weir 206a. Therefore,
the
partition 212 forces the water to follow a convoluted path from the filter
inlet 202 to the
weir 206a. In this embodiment, the convoluted path is in the form of a U-
shaped path. If
the partition 212 were not present, then water entering the sump 204 would
tend to flow
over the weir 206a without passing through the sterilising filter 214, and
sterilisation
would not take place.
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The excess water, now sterilised, spills over the weir 206a (arrow E) and
flows down
the filter outlet 208. The water collects at the base 100a of the collector
100 which is in
coinmunication with the piezo-electric device 102. The piezo-electric device
102 is set
to oscillate at a pre-determined frequency and magnitude such that sufficient
vibrational
energy is imparted to water molecules on the surface of the water in the
collector 100 to
overcome surface tension effects. Therefore, the water is turned into a fine
niist in the
interior space of the collector 100.
The fan 104 directs an airflow downwardly into the collector 100. This directs
the fine
mist towards, and down, the exhaust conduit 37 which leads to the outside of
the outer
case 12. This process continues until all the water contained within the
collector 100 is
efficiently aizd hygienically removed from the collector 100.
Figures 5a and 5b illustrate the removal of the liquid treatment module 30
from the
outer case 12 for maintenaa.lce or replacement. The liquid treatment module 30
is
removed downwardly from the hand dryer 10. In this embodiment, the filter 200
forms
part of the liquid treatment module 30 and is removable from the outer case 12
with the
liquid treatment module 30.
It will be understood that the invention is not to be limited to the precise
details
described above. Other variations and modifications will be apparent to the
skilled
reader.
For example, the drying apparatus need not take the form of a hand dryer. The
drying
apparatus could be a condenser-type laundry dryer. In such a laundry dryer,
water
evaporated from wet textiles in the dnun (cavity) of the laundry dryer can be
condensed,
filtered by a filtration unit and then removed by agitation or evaporation.
Further, the invention could be utilized in other forms of drying apparatus;
for example,
other forms of domestic or commercial drying apparatus such as washer-dryers,
ventilation-type laundry dryers or fiill-length body dryers.
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Additionally, other foims of liquid dispersion unit can be used to disperse
the collected
liquid; for example, an ultrasonic generator, a fan, a heating element or
electrolysing
apparatus. Any of these devices could be used in place of a piezo-electric
device to
agitate, evaporate or electrolyse the water (or other liquid) as required.
The liquid treatment module need not be located inside a chamber present in
the drying
apparatus. Other arrangements are possible; for exainple, the module could
form a part
of the outer case, or could be mounted on or outside the outer case of the
drying
apparatus.
Furtlier, the liquid treatment modLile need not be removed from the lower part
of the
drying apparatus. The liquid treatment module may form part of the upper side
or top of
the drying apparatus, and be removed sideways or upwardly depending upon the
requirements of the drying apparatus. Additionally, it need not be removable
and could
remain fixed inside the drying apparatus.
As a further variation, other forms of airflow generator are possible. For
example, an air
bleed or exhaust airflow could be taken from a motor unit. For example, the
motor unit
for driving the drying process of the hand dryer has a fan. This fan could be
used to
generate an airflow to vent the evaporated water to the outside of the drying
apparatus
rather than using an additional fan.
Additionally, the dimensions of the glass beads need not be 4 mm. They may be
varied
in size from 1 inm to 6 mm. Additionally, other types of particulate filter
media could
be used; for example, glass-fibre brushes, plastic brushes, porous ceramics,
plastic
beads or small stones. What is important is that the particulate filter is
formed from an
inert material with a density greater than 1 g/1. The size of the particulate
filter may be
varied and may be any size suitable to ensure that the majority of the
particulates are
filtered and removed from the water to prevent the sterilising filter from
clogging and
becoming blocked.
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As an additional variation, a nuinber of particulate filters may be provided.
They may be
located outside of the suinp, for example in the filter inlet to pre-filter
water before it
reaches the sump.
The sterilising filter need not be fonned of a resin with substantially
spherical particles
with dimensions in the range of 0.1 to 2 mm. Other particle shapes or sizes
could be
used, for- example by grinding. Alternatively, a single, porous bloclc of
resin could be
used. Further, the sterilising filter need not be formed from a resin. Other
inorganic host
media could be used; for example, inorganic polymers, metal chelates, metal
complexes
or crystal structures.
The loading of iodine need not be 500 g/l and may be within a preferred range
of 300 g/l
to 600 g/l. Further, the concentration of iodine released into the water may
also be
outside the range of 1 to 5 ppm. What is important is that the concentration
is high
enough to kill the bacteria in the water whilst low enough to avoid
discolouring the
water. Further, the volume of the sterilising filter can be varied, provided
it is sufficient
to sterilise the water.
Additionally, the anti-bacterial agent in the sterilising filter need not be
iodine and could
include alternative bacteria-killing media; for example, a halogen-containing
material or
a precursor to a halogen-containing material. Typical, non-exhaustive,
examples of
these are materials including: Chlorine, Bromine, Iodine, Hypochlorite or
Hypobromide. Alternatively, other methods of sterilising bacteria may be
implemented;
for example, Titaniuin dioxide or UV-radiation activated silver nanoparticles.
Further, the particulate, filter and sterilising filter need not be located
wholly in the
sump. They could be located above the sump, out of the water in the sump, or
partially
submerged in the water in the sump.
As a fizrther variation, the particulate-filtering media and the bacteria-
killing media need
not form separate stages in the filter and may be combined to form a single
tuiit.
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As a fu.rther variation, the filter need not be removable from the drying
apparatus. The
filter could remain inside the casing of the drying apparatus when the liquid
treatment
module is removed. The filter could either be removable separately from the
liquid
5 treatment module or be fixed permanently inside the casing of the drying
apparatus.
